阅读说明：本技术 用于推断燃料喷射压力的系统和方法及其用途 (System and method for inferring fuel injection pressure and use thereof ) 是由 约瑟夫·莱尔·托马斯 罗斯·戴卡斯特拉·普西福尔 于 2020-11-13 设计创作，主要内容包括：本公开提供了“用于推断燃料喷射压力的系统和方法及其用途”。提供了用于控制对车辆中的发动机的气缸的燃料喷射的方法和系统。在一个示例中,一种方法包括：监测与已经被命令将预定量的燃料喷射到发动机气缸中的燃料喷射器相关联的电能分布图；基于所述电能分布图来推断燃料喷射压力；以及基于所述推断的燃料喷射压力来控制后续燃料喷射。通过这种方式,在向所述燃料喷射器供应燃料的燃料轨不包括压力传感器或者所述压力传感器劣化的情况下,可以在不依赖于所述燃料轨中的所述压力传感器的情况下控制燃料喷射。(The present disclosure provides "systems and methods for inferring fuel injection pressure and uses thereof. Methods and systems for controlling fuel injection to a cylinder of an engine in a vehicle are provided. In one example, a method comprises: monitoring an electrical energy profile associated with a fuel injector that has been commanded to inject a predetermined amount of fuel into a cylinder of the engine; inferring a fuel injection pressure based on the electrical energy profile; and controlling a follow-up fuel injection based on the inferred fuel injection pressure. In this way, in the case where the fuel rail supplying fuel to the fuel injector does not include a pressure sensor or the pressure sensor deteriorates, fuel injection can be controlled without relying on the pressure sensor in the fuel rail.)

1. A method, comprising:

commanding injection of a predetermined amount of fuel into a cylinder of an engine via a fuel injector;

monitoring an electrical energy profile associated with the fuel injector in response to the command;

inferring a fuel injection pressure based on the electrical energy profile; and

controlling a follow-up fuel injection based on the inferred fuel injection pressure.

2. The method of claim 1, wherein the fuel to be injected into the cylinder of the engine is contained in a fuel rail; and is

Wherein the fuel rail does not include a pressure sensor for measuring the fuel injection pressure.

3. The method of claim 2, wherein the fuel rail is a low pressure fuel rail; and is

Wherein the fuel injector is a port fuel injector.

4. The method of claim 2, wherein the fuel rail is a high pressure fuel rail; and is

Wherein the fuel injector is a direct fuel injector.

5. The method of claim 1, wherein the fuel injector is an open-in configuration fuel injector.

6. The method of claim 1, wherein controlling the subsequent fuel injection comprises controlling a fuel injection pulse width of a next fuel injection based on a firing sequence of the engine.

7. The method of claim 1, further comprising determining a fuel injector full open time based on the electrical energy profile; and

inferring the fuel injection pressure based on the fuel injector full open time.

8. The method of claim 1, further comprising determining a fuel injector full off time based on the electrical energy profile; and

inferring the fuel injection pressure based on the fuel injector full closure time.

9. A system for a vehicle, comprising:

a fuel system including a pulsed lift pump that supplies fuel from a fuel tank to a low pressure fuel rail;

a set of port fuel injectors supplying fuel from the low pressure fuel rail to a set of cylinders of an engine; and

a controller having computer readable instructions stored on a non-transitory memory that, when executed, cause the controller to:

command injection of a predetermined amount of the fuel into a cylinder of the set of cylinders via a port fuel injector of the set of port fuel injectors;

determining a fuel injection pressure of the fuel in the fuel rail based on a port fuel injector full open time and/or a fuel injector full close time; and

the fuel injection pulse width of the subsequent fuel injection to another engine cylinder is controlled based on the fuel injection pressure.

10. The system of claim 9, wherein the set of port fuel injectors are open-in fuel injectors comprising a valve mechanism having an opening rate and a closing rate that are a function of the fuel injection pressure.

11. The system of claim 9, wherein the low pressure fuel rail does not include a pressure sensor.

12. The system of claim 9, wherein the controller stores further instructions to continuously update the fuel injection pressure based on each fuel injector full open time and/or each fuel injector full close time when the engine is operating in a combustion mode.

13. The system of claim 9, wherein the controller stores further instructions to infer the port fuel injector full open time and/or the fuel injector full close time based on monitored power profiles corresponding to activation and/or deactivation of the fuel injector, respectively.

14. The system of claim 9, wherein the fuel rail comprises a pressure sensor; and is

Wherein the controller stores further instructions to indicate degradation of the pressure sensor in response to the fuel injection pressure differing from a monitored fuel injection pressure indicated by the pressure sensor by more than a predetermined threshold; and is

Controlling the fuel injection pulse width of the follow-up fuel injection to another cylinder based on the fuel injection pressure in response to the pressure sensor being indicated as degraded.

15. The system of claim 9, wherein the port fuel injector full open time is independent of a voltage supplied to the port fuel injector.

Technical Field

The present description relates generally to methods and systems for inferring fuel injection pressure based on a power profile (profile) corresponding to activation and deactivation of a fuel injector, and uses for such inferred fuel injection pressure.

Background

Engines may be configured with direct fuel injectors (DI) for injecting fuel directly into an engine cylinder and/or Port Fuel Injectors (PFI) for injecting fuel into an intake port of an engine cylinder. The basic concept of fuel injection is to know the fuel injection pressure by measurement (e.g., via a pressure sensor) or based on a pressure regulator setting. Based on the fuel injection pressure, the control strategy may calculate the necessary fuel injector opening time to achieve the desired injection quantity for each fuel injection event.

For example, it is known that PFI systems can be used without an injection pressure sensor, with a pressure regulator being employed to bleed off excess fuel pressure, thereby mechanically achieving a constant fuel line/rail pressure. This embodiment may save the cost of the pressure sensor and reduce any adverse conditions resulting from conditions in which the pressure sensor may degrade. However, in the case of a pulsed lift fuel pump (pulsed lift fuel pump) for supplying fuel to the fuel injectors, it may not be desirable to operate such a fuel system without a pressure sensor because of the possibility of failure modes introducing large pressure inaccuracies in the open loop behavior of such a fuel system. Accordingly, it is recognized herein that it may be desirable to rely on other methods to infer fuel injection pressure for a fuel system including at least a pulsed lift pump and a port fuel injector, such that reliance on dedicated pressure sensors may be reduced or avoided. In a similar manner, where a pressure sensor is included in such a fuel system that includes a pulsed lift pump and at least a port fuel injector, another way to have inferred fuel rail pressure may enable robust diagnostics to determine when the pressure sensor exhibits degraded functionality and may enable the fuel system to operate effectively in place of the degraded pressure sensor.

Disclosure of Invention

The inventors have recognized the above-mentioned problems, and have developed herein systems and methods for at least partially solving the above-mentioned problems. In one example, a method comprises: commanding injection of a predetermined amount of fuel into a cylinder of an engine via a fuel injector; monitoring an electrical energy profile associated with the fuel injector; inferring a fuel injection pressure based on the monitored electrical energy profile; and controlling a follow-up fuel injection based on the inferred fuel injection pressure. In this way, operation of the fuel injector itself may provide a reliable estimate of fuel injection pressure, which may be used for subsequent control of the fuel system and/or for diagnostic means.

As one example, the fuel to be injected into the cylinder of the engine may be contained in a fuel rail, wherein the fuel rail does not include a pressure sensor for measuring the fuel injection pressure. In one example, the fuel rail may be a low pressure fuel rail, wherein the fuel injectors are port fuel injectors, or in another example, the fuel rail may be a high pressure fuel rail, wherein the fuel injectors are direct fuel injectors. In any example, the fuel injector may be an internal opening fuel injector.

As another example, controlling the subsequent fuel injection may include controlling a fuel injection pulse width of a next fuel injection based on a firing order of the engine.

As another example, the method may include determining a fuel injector full open time based on the electrical energy profile, and inferring the fuel injection pressure based on the fuel injector full open time. Additionally or alternatively, the method may include determining a fuel injector full close time based on the electrical energy profile, and inferring the fuel injection pressure based on the fuel injector full close time.

The above advantages and other advantages and features of the present description will be apparent from the following detailed description when taken alone or in conjunction with the accompanying drawings.

It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. This is not intended to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Additionally, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.

Drawings

FIG. 1 schematically depicts an exemplary embodiment of a cylinder of an internal combustion engine;

FIG. 2 schematically depicts an exemplary embodiment of a fuel system configured for port injection and direct injection that may be used with the engine of FIG. 1;

FIG. 3 depicts an exemplary open-in fuel injector of the present disclosure;

FIG. 4 depicts a high level exemplary method for controlling one or both of port fuel injection and direct injection of fuel to an engine cylinder;

5A-5E depict exemplary diagrams detailing how an electrical energy profile corresponding to activation and/or deactivation of a fuel injector of the type depicted in FIG. 3 may be used to infer opening and closing times of the fuel injector;

6A-6B depict exemplary graphs detailing how fuel pressure can be determined based on an understanding of opening and closing time inferences based on power profiles for activation and deactivation of fuel injectors;

FIG. 7 depicts a high level exemplary method for inferring fuel pressure based on opening time determinations and/or closing time determinations of individual fuel injectors;

FIG. 8 depicts a high-level exemplary method for determining whether a fuel rail pressure sensor is functioning as expected or desired based on fuel pressure inferences made via the method of FIG. 7;

FIG. 9 depicts a high level exemplary method for inferring a presence or absence of fuel system degradation of a fuel system including a lift pump and a fuel rail without a pressure sensor;

10A-10B depict exemplary maps illustratively conveying the method of FIG. 9;

11A-11B depict exemplary graphs showing how data obtained via the method of FIG. 9 may be used to infer the presence or absence of fuel system degradation;

FIG. 12 depicts an alternative method for inferring the presence or absence of fuel system degradation of a fuel system including a lift pump and a fuel rail without a pressure sensor;

13A-13B depict exemplary diagrams illustratively conveying the method of FIG. 12;

14A-14B depict exemplary graphs showing how data obtained via the method of FIG. 12 may be used to infer the presence or absence of fuel system degradation.

Detailed Description

The following description relates to systems and methods for inferring fuel pressure in a fuel rail of a vehicle fuel system based on an electrical energy profile monitored during activation and/or deactivation of fuel injectors supplying fuel to an engine of the vehicle system. Accordingly, FIG. 1 depicts an exemplary vehicle system including a fuel system and an engine system coupled thereto. FIG. 2 depicts a detailed view of the fuel system of FIG. 1 showing a dual fuel rail fuel system including a lift pump located in a fuel tank and a high pressure fuel pump supplying fuel to one of the two fuel rails. FIG. 2 depicts a low pressure fuel rail supplying fuel to port injectors and a high pressure fuel rail supplying fuel to direct injectors. The method for inferring fuel pressure as discussed herein is related to an open-ended fuel injector of the type shown in FIG. 3. FIG. 4 depicts a high level method for controlling port injection and/or direct injection of fuel into an engine cylinder.

As described above, the systems and methods discussed herein relate to inferring fuel pressure based on an electrical energy profile monitored during activation and/or deactivation of a fuel injector of the type depicted in FIG. 3. 5A-5E depict exemplary illustrations of how current and/or voltage profiles may be used to infer opening time determinations and/or closing time determinations for the fuel injectors of the present disclosure. Fig. 6A-6B depict graphs showing how such open time determinations and/or close time determinations can enable inferring fuel pressure in the fuel rail.

FIG. 7 depicts an exemplary method for inferring fuel pressure based on an electrical energy profile corresponding to activation and/or deactivation of a fuel injector of the present disclosure. FIG. 8 depicts an exemplary method for pressure sensor rationality checking a fuel rail pressure sensor based on fuel pressure inferred via the method of FIG. 7. FIG. 9 depicts a high-level exemplary method for inferring the presence or absence of fuel system degradation under conditions in which the fuel system includes a fuel rail and a lift pump without a pressure sensor. 10A-10B depict exemplary maps illustratively detailing the method of FIG. 9, and 11A-11B depict exemplary maps illustrating how the method of FIG. 9 may be used to infer the presence or absence of fuel system degradation. FIG. 12 depicts an alternative high-level exemplary method of the method of FIG. 9 for inferring the presence or absence of fuel system degradation if the fuel system includes a fuel rail and a lift pump without a pressure sensor. Fig. 13A-13B depict exemplary maps illustratively detailing the method of fig. 12, and fig. 14A-14B depict exemplary maps illustrating how the method of fig. 12 may be used to infer the presence or absence of fuel system degradation.

Turning now to FIG. 1, an example of a combustion chamber or cylinder of an internal combustion engine 10 included in a vehicle system 100 is depicted. Engine 10 may be controlled at least partially by a control system including controller 12 and by input from a vehicle operator 130 via an input device 132. In this example, the input device 132 includes an accelerator pedal and a pedal position sensor 134 for generating a proportional pedal position signal PP. The cylinders (also referred to herein as "combustion chambers") 14 of the engine 10 may include combustion chamber walls 136 with pistons 138 positioned in the combustion chamber walls 136. Piston 138 may be coupled to crankshaft 140 such that reciprocating motion of the piston is translated into rotational motion of the crankshaft. Crankshaft 140 may be coupled to at least one drive wheel of a passenger vehicle via a transmission system. Further, a starter motor (not shown) may be coupled to crankshaft 140 via a flywheel to enable a starting operation of engine 10.

Cylinder 14 may receive intake air via a series of intake passages 142, 144, and 146. Intake passage 146 may communicate with other cylinders of engine 10 in addition to cylinder 14. In some examples, one or more of the intake passages may include a boosting device, such as a turbocharger or a supercharger. For example, FIG. 1 shows engine 10 configured with a turbocharger including a compressor 174 disposed between intake passages 142 and 144, and an exhaust turbine 176 disposed along exhaust passage 148. Where the boosting device is configured as a turbocharger, compressor 174 may be at least partially powered by exhaust turbine 176 via shaft 180. However, in other examples, such as where engine 10 is provided with a supercharger, exhaust turbine 176 may optionally be omitted, where compressor 174 may be powered by mechanical input from the motor or the engine. A throttle 162 including a throttle plate 164 may be disposed along an intake passage of the engine for varying the flow rate and/or pressure of intake air provided to the engine cylinders. For example, throttle 162 may be located downstream of compressor 174, as shown in FIG. 1, or alternatively, may be disposed upstream of compressor 174.

Exhaust passage 148 may receive exhaust gases from other cylinders of engine 10 in addition to cylinder 14. Exhaust gas sensor 128 is shown coupled to exhaust passage 148 upstream of emission control device 178. Sensor 128 may be selected from a variety of suitable sensors for providing an indication of exhaust gas air/fuel ratio such as, for example, a linear oxygen sensor or UEGO (universal or wide-range exhaust gas oxygen), a two-state oxygen sensor or EGO (as depicted), a HEGO (heated EGO), a NOx, HC, or CO sensor. Emission control device 178 may be a Three Way Catalyst (TWC), NOx trap, various other emission control devices, or combinations thereof.

Each cylinder of engine 10 may include one or more intake valves and one or more exhaust valves. For example, cylinder 14 is shown to include at least one intake poppet valve 150 and at least one exhaust poppet valve 156 located at an upper region of cylinder 14. In some examples, each cylinder of engine 10 (including cylinder 14) may include at least two intake poppet valves and at least two exhaust poppet valves located at an upper region of the cylinder.

Intake valve 150 may be controlled by controller 12 via actuator 152. Similarly, exhaust valve 156 may be controlled by controller 12 via actuator 154. During some conditions, controller 12 may vary the signals provided to actuators 152 and 154 to control the opening and closing of the respective intake and exhaust valves. The position of intake valve 150 and exhaust valve 156 may be determined by respective valve position sensors (not shown). The valve actuators may be electrically actuated, cam actuated, or a combination thereof. The intake and exhaust valve timing may be controlled simultaneously, or any of the possible configurations of variable intake cam timing, variable exhaust cam timing, dual independent variable cam timing, or fixed cam timing may be used. Each cam actuation system may include one or more cams and may utilize one or more of Cam Profile Switching (CPS), Variable Cam Timing (VCT), Variable Valve Timing (VVT), and/or Variable Valve Lift (VVL) systems that may be operated by controller 12 to vary valve operation. For example, cylinder 14 may alternatively include an intake valve controlled via electric valve actuation and an exhaust valve controlled via cam actuation (including CPS and/or VCT). In other examples, the intake and exhaust valves may be controlled by a common valve actuator or actuation system or a variable valve timing actuator or actuation system.

Cylinder 14 may have a compression ratio, which is the ratio of the volume of piston 138 at bottom center to top center. In one example, the compression ratio is at 9: in the range of 1 to 10: 1. However, in some examples where different fuels are used, the compression ratio may be increased. This may occur, for example, when higher octane fuels or fuels with higher latent enthalpy of vaporization are used. If direct injection is used, the compression ratio may also be increased due to the effect of direct injection on engine knock.

In some examples, each cylinder of engine 10 may include a spark plug 192 for initiating combustion. Ignition system 190 can provide an ignition spark to combustion chamber 14 via spark plug 192 in response to spark advance signal SA from controller 12, under select operating modes. However, in some embodiments, spark plug 192 may be omitted, such as where engine 10 may initiate combustion by auto-ignition or by fuel injection, as is the case with some diesel engines.

In some examples, each cylinder of engine 10 may be configured with one or more fuel injectors for providing fuel thereto. As a non-limiting example, cylinder 14 is shown to include two fuel injectors 166 and 170. Fuel injectors 166 and 170 may be configured to deliver fuel received from fuel system 8. Fuel injector 166 is shown coupled directly to cylinder 14 for injecting fuel directly therein in proportion to the pulse width of signal FPW-1 received from controller 12 via electronic driver 168. In this manner, fuel injector 166 provides what is known as direct injection (hereinafter "DI") of fuel into combustion cylinder 14. Although FIG. 1 shows injector 166 positioned to one side of cylinder 14, injector 166 may alternatively be located above the top of the piston, such as near spark plug 192. Because some alcohol-based fuels have a lower volatility, such a location may improve mixing and combustion when operating an engine using an alcohol-based fuel. Alternatively, the injector may be located above and near the intake valve to improve mixing. Fuel may be delivered to fuel injector 166 from a fuel tank of fuel system 8 via a high pressure fuel pump and fuel rail. Further, the fuel tank may have a pressure sensor that provides a signal to controller 12.

Fuel injector 170 is shown disposed in intake passage 146 rather than cylinder 14 in a configuration that provides so-called port injection of fuel (hereinafter "PFI") into the intake port upstream of cylinder 14. Fuel injector 170 may inject fuel received from fuel system 8 in proportion to the pulse width of signal FPW-2 received from controller 12 via electronic driver 171. It will be appreciated that driver 168 and driver 171 may be the same type of driver in some examples (e.g., a port fuel injector may be driven by a direct injection driver in some examples to reduce or eliminate the dependence of the battery voltage on the opening time parameter of the port fuel injector). Thus, in some examples, the types of drivers used to drive port fuel injectors and direct injectors may be the same, while in other examples, the types of drivers used to drive port fuel injectors and direct injectors may be different. However, it is understood that PFI actuators may not be used to actuate direct fuel injectors.

In an alternative example, each of fuel injectors 166 and 170 may be configured as a direct fuel injector for injecting fuel directly into cylinder 14. In yet another example, each of fuel injectors 166 and 170 may be configured as a port fuel injector for injecting fuel upstream of intake valve 150. In still other examples, cylinder 14 may include only a single fuel injector configured to receive different fuels from the fuel system in different relative amounts as a fuel mixture, and further configured to inject this fuel mixture directly into the cylinder as a direct fuel injector, or upstream of the intake valve as a port fuel injector. Thus, it should be understood that the fuel system described herein should not be limited by the particular fuel injector configuration described herein by way of example.

Fuel may be delivered to the cylinder through both injectors during a single cycle of the cylinder. For example, each injector may deliver a portion of the total fuel injection combusted in cylinder 14. Further, the distribution and/or relative amount of fuel delivered from each injector may vary with operating conditions, such as engine load, knock, and exhaust temperature, such as described below. Port injected fuel may be delivered during an open intake valve event, a closed intake valve event (e.g., substantially before the intake stroke), and during open and closed intake valve operation. Similarly, for example, directly injected fuel may be delivered during the intake stroke as well as partially during the previous exhaust stroke, during the intake stroke, and partially during the compression stroke. Thus, the injected fuel may be injected from the port injector and the direct injector at different timings, even for a single combustion event. Further, multiple injections of delivered fuel may be performed per cycle for a single combustion event. Multiple injections may be performed during a compression stroke, an intake stroke, or any suitable combination thereof.

Fuel injectors 166 and 170 may have different characteristics. These characteristics include size differences, for example, one injector may have a larger injection orifice than another injector. Other differences include, but are not limited to, different spray angles, different operating temperatures, different orientations, different injection timings, different spray characteristics, different locations, and the like. Further, depending on the distribution ratio of the injected fuel between injectors 170 and 166, different effects may be achieved.

The fuel system 8 may include one or more fuel tanks. One or more fuel tanks in fuel system 8 may hold fuel of different fuel types, such as fuel having different fuel qualities and different fuel compositions. The differences may include different alcohol content, different water content, different octane number, different heat of vaporization, different fuel blends, and/or combinations thereof, and the like. One example of fuels with different heats of vaporization may include gasoline with a lower heat of vaporization as a first fuel type and ethanol with a higher heat of vaporization as a second fuel type. In another example, an engine may use gasoline as the first fuel type and an alcohol-containing fuel blend, such as E85 (which is approximately 85% ethanol and 15% gasoline) or M85 (which is approximately 85% methanol and 15% gasoline), as the second fuel type. Other useful materials include water, methanol, mixtures of alcohols and water, mixtures of water and methanol, mixtures of alcohols, and the like.

In still other examples, the fuel may be an alcohol blend with different alcohol constituents, where the first fuel type may be a gasoline alcohol blend with a lower alcohol concentration, such as E10 (which is about 10% ethanol), and the second fuel type may be a gasoline alcohol blend with a greater alcohol concentration, such as E85 (which is about 85% ethanol). Additionally, the first and second fuels may also differ in other fuel qualities, such as differences in temperature, viscosity, octane number, and the like. Further, the fuel properties of one or both fuel tanks may change frequently, for example, due to day-to-day changes in fuel tank refilling.

Although the above discussion relates to a fuel system having two fuel tanks, it may be appreciated that in other examples, the fuel system may include only a single fuel tank without departing from the scope of the present disclosure.

The controller 12 is shown in fig. 1 as a microcomputer including: microprocessor unit 106, input/output ports 108, an electronic storage medium for executable programs and calibration values (shown in this particular example as a non-transitory read only memory chip 110 for storing executable instructions), a random access memory 112, a keep alive memory 114, and a data bus. Controller 12 may receive various signals from sensors coupled to engine 10, including, in addition to those signals previously discussed: a measurement of intake Mass Air Flow (MAF) from mass air flow sensor 122; engine Coolant Temperature (ECT) from temperature sensor 116 coupled to cooling sleeve 118; a surface ignition pickup signal (PIP) from Hall effect sensor 120 (or other type of sensor) coupled to crankshaft 140; a Throttle Position (TP) from a throttle position sensor; and a manifold absolute pressure signal (MAP) from sensor 124. An engine speed signal (RPM) may be generated by controller 12 from signal PIP. Manifold pressure signal MAP from a manifold pressure sensor may be used to provide an indication of vacuum or pressure in the intake manifold. The controller 12 receives signals from the various sensors of FIG. 1 and employs the various actuators of FIG. 1 to adjust engine operation based on the received signals and instructions stored on a memory of the controller.

As described above, FIG. 1 shows only one cylinder of a multi-cylinder engine. Thus, each cylinder may similarly include its own set of intake/exhaust valves, fuel injectors, spark plugs, and the like. It should be appreciated that engine 10 may include any suitable number of cylinders, including 2, 3, 4, 5, 6, 8, 10, 12, or more cylinders. Further, each of these cylinders may include some or all of the various components described and depicted by fig. 1 with reference to cylinder 14.

The vehicle system 100 may include multiple torque sources available for use by one or more vehicle wheels 175. In the illustrated example, the vehicle system 100 is a hybrid electric vehicle system (HEV) that includes an electric machine 153, however in other examples, the vehicle system may not be a hybrid electric vehicle system without departing from the scope of the present disclosure. The electric machine 153 may be a motor or a motor/generator. When the one or more clutches 172 are engaged, the crankshaft 140 of the engine 10 and the electric machine 153 are connected to wheels 175 via the transmission 155. In the depicted example, a first clutch is disposed between crankshaft 140 and motor 153, and a second clutch is disposed between motor 153 and transmission 155. Controller 12 may send signals to the actuator of each clutch 172 to engage or disengage the clutch to connect or disconnect the crankshaft with motor 153 and components connected thereto, and/or to connect or disconnect motor 153 with transmission 155 and components connected thereto. The transmission 155 may be a gearbox, a planetary gear system, or another type of transmission. The powertrain may be configured in various ways, including being configured as a parallel, series, or series-parallel hybrid vehicle.

The electric machine 153 receives power from a traction battery 158 (also described herein as an on-board energy storage device, or battery) to provide torque to the wheels 175. The electric machine 153 may also function as a generator to provide electrical power to charge the traction battery 158, such as during braking operations.

The on-board energy storage device 158 may periodically receive electrical energy from a power source 191 resident external to the vehicle (e.g., not part of the vehicle), as indicated by arrow 194. As a non-limiting example, the vehicle system 100 may be configured as a plug-in hybrid electric vehicle (PHEV), where electrical energy may be supplied from the power source 191 to the energy storage device 158 via an electrical energy transfer cable 193. During operation to recharge energy storage device 158 from power source 191, electrical transmission cable 193 may electrically couple energy storage device 158 and power source 191. When the vehicle propulsion system is operated to propel the vehicle, electrical transmission cable 193 may be disconnected between power source 191 and energy storage device 158. The controller 12 may identify and/or control an amount of electrical energy stored at the energy storage device, which may be referred to as a state of charge (SOC).

In other examples, the electrical transmission cable 193 may be omitted, wherein electrical energy may be wirelessly received at the energy storage device 158 from the power source 191. For example, the energy storage device 158 may receive electrical energy from the power source 191 via one or more of electromagnetic induction, radio waves, and electromagnetic resonance. Thus, it should be understood that any suitable method may be used to recharge energy storage device 158 from a power source that does not form part of the vehicle.

FIG. 2 schematically depicts an exemplary embodiment 200 of fuel system 8 discussed above in FIG. 1. The fuel system 8 may be operated to deliver fuel to an engine, such as the engine 10 of FIG. 1. The fuel system 8 may be operated by a controller to perform some or all of the operations described with reference to the method of fig. 3.

The fuel system 8 includes a fuel storage tank 210 for storing fuel on board the vehicle, a low pressure fuel pump (LPP)212 (also referred to herein as a pulsed fuel lift pump 212), and a high pressure fuel pump (HPP)214 (also referred to herein as a fuel injection pump 214). Fuel may be provided to fuel tank 210 via refueling passage 204. In one example, the LPP 212 may be an electric low pressure fuel pump disposed at least partially within the fuel tank 210. The LPP 212 may be operated by the controller 12 to provide fuel to the HPP214 via a fuel passage 218. The LPP 212 may be configured as a so-called fuel lift pump. As one example, the LPP 212 may be a turbine (e.g., centrifugal) pump that includes an electric (e.g., DC) pump motor, whereby the pressure increase across the pump and/or the volumetric flow rate through the pump may be controlled by varying the power provided to the pump motor (thereby increasing or decreasing the motor speed). For example, as the controller reduces the power provided to the lift pump 212, the volumetric flow rate and/or the pressure increase across the lift pump may be reduced. The volumetric flow rate and/or pressure increase across the pump may be increased by increasing the power provided to the lift pump 212. As one example, the power supplied to the low pressure pump motor may be obtained from an alternator or other energy storage device (not shown) on the vehicle, whereby the control system may control the electrical load used to power the low pressure pump. Thus, by varying the voltage and/or current provided to the low pressure fuel pump, the flow rate and pressure of the fuel provided at the inlet of high pressure fuel pump 214 is adjusted.

The LPP 212 may be fluidly coupled to a filter 217 that may remove small impurities contained in the fuel that may adversely affect the fuel processing components. A check valve 213, which may facilitate fuel delivery and maintain fuel line pressure, may be positioned fluidly upstream of the filter 217. With the check valve 213 upstream of the filter 217, the compliance of the low pressure passage 218 may be increased because the volume of the filter may be physically larger. Further, a pressure relief valve 219 may be used to limit the fuel pressure in the low pressure passage 218 (e.g., the output from the lift pump 212). The pressure relief valve 219 may include, for example, a ball and spring mechanism that seats and seals at a specified pressure differential. The pressure differential set point at which the pressure relief valve 219 may be configured to open may assume various suitable values; as a non-limiting example, the set point may be 6.4 bar or 5 bar (g). The orifice 223 may be used to allow air and/or fuel vapor to bleed out of the lift pump 212. This bleeding at the orifice 223 may also be used to power a jet pump used to transfer fuel from one location within the fuel tank 210 to another. In one example, an orifice check valve (not shown) may be placed in series with orifice 223. In some embodiments, the fuel system 8 may include one or more (e.g., a series of) check valves fluidly coupled to the low-pressure fuel pump 212 to prevent fuel from leaking back upstream of the valves. In this context, upstream flow refers to the fuel flow traveling from the fuel rail 250, 260 toward the LPP 212, while downstream flow refers to the nominal fuel flow direction from the LPP toward the HPP214 and on the HPP214 to the fuel rail.

The fuel lifted by the LPP 212 may be supplied at low pressure into a fuel passage 218 leading to the inlet 203 of the HPP 214. The HPP214 may then deliver fuel to a first fuel rail 250 coupled to one or more fuel injectors of a first group of direct injectors 252 (also referred to herein as a first injector group, with reference to fuel injectors 166 in FIG. 1). The fuel lifted by the LPP 212 may also be supplied to a second fuel rail 260 coupled to one or more fuel injectors of a second set of port injectors 262 (also referred to herein as a second injector set, with reference to fuel injectors 170 in fig. 1). The HPP214 may be operated to raise the pressure of fuel delivered to a first fuel rail to above a lift pump pressure, where the first fuel rail coupled to the direct injector group is operated at a high pressure. As a result, high pressure DI can be achieved while PFI can be operated at lower pressures.

Although each of the first and second fuel rails 250, 260 is shown as distributing fuel to four fuel injectors in the respective injector groups 252, 262, it should be appreciated that each fuel rail 250, 260 may distribute fuel to any suitable number of fuel injectors. As one example, the first fuel rail 250 may distribute fuel to one fuel injector of a first injector group 252 (e.g., a direct injector) for each cylinder of the engine, while the second fuel rail 260 may distribute fuel to one fuel injector of a second injector group 262 (e.g., a port injector) for each cylinder of the engine. Controller 12 may actuate each of port injectors 262 individually via port injection driver 171 and each of direct injectors 252 via direct injection driver 168. Controller 12, drives 171, 168, and other suitable engine system controllers may comprise a control system. Although the drivers 171, 168 are shown external to the controller 12, it should be understood that in other examples, the controller 12 may include the drivers 171, 168, or may be configured to provide the functionality of the drivers 171, 168. The controller 12 may include additional components not shown, such as those included in the controller 12 of fig. 1. As discussed above, in some examples, driver 171 may be a direct injection driver, and driver 168 may also be a direct injection driver. As described above, relying on the DI driver may reduce or eliminate the dependence of battery voltage on the opening time parameter of the port fuel injector.

The HPP214 may be an engine-driven positive displacement pump. As one non-limiting example, the HPP214 may be a Bosch HDP5 high pressure pump that utilizes solenoid activated control valves (e.g., fuel quantity regulators, magnetic solenoid valves, etc.) to vary the effective pump volume per pump stroke. The outlet check valve 274 of the HPP is mechanically controlled by an external controller, rather than electronically. In contrast to the motor-driven LPP 212, the HPP214 may be mechanically driven by the engine, however, in other examples, the HPP214 may be electronically controlled without departing from the scope of the present disclosure. The HPP214 includes a pump piston 228, a pump compression chamber 205 (also referred to herein as a compression chamber), and a step space 227. The pump piston 228 receives mechanical input from the engine crankshaft or camshaft via the cam 230, thereby operating the HPP according to the principles of a cam-driven, single cylinder pump. A sensor (not shown in fig. 2) may be positioned near the cam 230 to enable determination of the angular position of the cam (e.g., between 0 and 360 degrees), which may be relayed to the controller 12.

A lift pump fuel pressure sensor 231 may be positioned along the fuel passage 218 between the lift pump 212 and the high pressure fuel pump 214. In this configuration, the reading from the sensor 231 may be interpreted as an indication of the fuel pressure of the lift pump 212 (e.g., the lift pump outlet fuel pressure) and/or the inlet pressure of the high pressure fuel pump 214. The readings from the sensor 231 may be used to evaluate the operation of various components in the fuel system 8, determine whether to provide sufficient fuel pressure to the high-pressure fuel pump 214 such that the high-pressure fuel pump intakes liquid fuel rather than fuel vapor, and/or to minimize the average power supplied to the lift pump 212.

The first fuel rail 250 may include a first fuel rail pressure sensor 248 for providing an indication of direct injection fuel rail pressure to the controller 12, although the first fuel rail 250 may not include a first fuel rail pressure sensor in other examples without departing from the scope of the present disclosure. Likewise, the second fuel rail 260 may include a second rail pressure sensor 258 for providing an indication of port injection rail pressure to the controller 12, although the second fuel rail 260 may not include a second rail pressure sensor in other examples without departing from the scope of the present disclosure. An engine speed sensor 233 may be used to provide an indication of engine speed to controller 12. Where the HPP214 is mechanically driven by the engine 10, for example via a crankshaft or camshaft, an indication of engine speed may be used to identify the speed of the HPP 214.

The first fuel rail 250 is coupled to the outlet 208 of the HPP214 along a fuel passage 278. An outlet check valve 274 and a pressure relief valve (also referred to as a pump relief valve) 272 may be positioned between the outlet 208 of the HPP214 and the first (DI) fuel rail 250. Pump relief valve 272 may be coupled to bypass passage 279 of fuel passage 278. The outlet check valve 274 opens to allow fuel to flow from the high pressure pump outlet 208 into the fuel rail only when the pressure at the outlet of the direct injection fuel pump 214 (e.g., the compression chamber outlet pressure) is higher than the fuel rail pressure. The pump relief valve 272 may limit the pressure in the fuel passage 278 downstream of the HPP214 and upstream of the first fuel rail 250. For example, pump relief valve 272 may limit the pressure in fuel passage 278 to 200 bar. Pump relief valve 272 allows fuel to flow from DI fuel rail 250 toward pump outlet 208 when the fuel rail pressure is greater than a predetermined pressure. Valves 244 and 242 work in combination to maintain low pressure fuel rail 260 pressurized to a predetermined low pressure. The pressure relief valve 242 helps to limit pressure that may build up in the fuel rail 260 due to thermal expansion of the fuel. Although the above discussion includes pump relief valve 272 and relief valve 242, in other examples, pump relief valve 272 and relief valve 242 may not be included without departing from the scope of the present disclosure.

Based on engine operating conditions, fuel may be delivered by one or more port injectors 262 and direct injectors 252. For example, during high load conditions, fuel may be delivered to the cylinder in a given engine cycle via direct injection only, where port injector 262 may be disabled. In another example, during mid-load conditions, fuel may be delivered to the cylinder in a given engine cycle via each of direct injection and port injection. As yet another example, during low load conditions, engine start, and warm idle conditions, fuel may be delivered to the cylinder in a given engine cycle via port-only injection, where the direct injector 252 may be disabled.

It should be noted here that the high-pressure pump 214 of fig. 2 is presented as an illustrative example of one possible configuration of a high-pressure pump. The components shown in FIG. 2 may be removed and/or replaced, and additional components not currently shown may be added to the pump 214 while still maintaining the ability to deliver high pressure fuel to both the direct injection fuel rail and the port injection fuel rail.

The controller 12 may also control the operation of each of the fuel pumps 212 and 214 to adjust the amount, pressure, flow rate, etc. of fuel delivered to the engine. As one example, controller 12 may vary a pressure setting of the fuel pump, a pump stroke amount, a pump duty cycle command, and/or a fuel flow rate to deliver fuel to different locations of the fuel system. A driver (not shown) electrically coupled to the controller 12 may be used to send control signals to the low pressure pump as needed to adjust the output (e.g., speed, flow output, and/or pressure) of the low pressure pump.

FIG. 3 shows a schematic diagram of an exemplary fuel injector 300 that may be used to supply fuel from a fuel system (e.g., fuel system 8) to an engine (e.g., engine 10). The fuel injector 300 may be any type of injector. For example, fuel injector 300 may be a direct injector (e.g., direct injector 166 of FIG. 1) or a port fuel injector (e.g., port injector 170 of FIG. 1). It will be appreciated that based on the manner in which the fuel injector opens, the fuel injector 300 may be referred to as an inward opening injector, as will be set forth in more detail below.

The fuel injector 300 includes a nozzle body 302, which may be used as a valve seat support and part of a valve housing. The valve mechanism 303 within the nozzle body 302 may be displaced in an axial direction (e.g., along a central axis 355 of the fuel injector 300). The valve mechanism 303 may be, for example, a pintle or needle that is slidable in the direction of the central axis 355. In some examples, the valve mechanism 303 may be at least partially constructed of a permanently magnetized material. For example, the valve mechanism 303 may be constructed of a material, such as iron, that can be magnetized by an external magnetic field and remain magnetized after the external magnetic field is removed. In other examples, the valve mechanism 303 may be substantially composed of a ferromagnetic material (such as iron, nickel, cobalt, and/or alloys thereof).

The fuel injector 300 may be an inward opening fuel injector having at least one ejection orifice 307 formed in a valve seat body 305 such that when the injector driver circuit 311 is activated to actuate the valve mechanism, the valve mechanism 303 lifts off the valve mechanism seat 305 to create a gap between the valve opening and closing member 304 and the valve seat surface 306 such that fuel may flow out of the orifice 307.

The valve mechanism 303 is coupled to a valve opening and closing member 304 that cooperates with a valve seat surface 306 formed on a valve mechanism seat body 305 to form a seal seat. The valve mechanism seat body 305 may be fixedly coupled to the downstream end 356 of the nozzle body 302. However, the valve seat surface 306 may also be formed directly on the base portion of the nozzle body 302. For example, the valve opening and closing member 304 may be spherical or frustoconical such that, in the closed position, the valve opening and closing member 304 engages the valve seat surface 306 to shut off fuel flow through the fuel injector via an orifice (e.g., orifice 307) located in the downstream end 356 of the fuel injector.

In some examples, the valve mechanism 303 may penetrate the armature 320 in an interior opening in the upstream valve housing 337. The armature 320 may be coupled to the valve mechanism 303 so as to be axially displaceable in the direction of the central axis 355. The path of the magnetic armature 320 in the direction of the central axis 355 may be limited by a first upper flange 321, which may be integrally formed with the upstream portion of the valve mechanism 303, and a second lower flange 322, which is coupled to the valve mechanism 303 downstream of the armature 320. A return spring 323 is supported on the first flange 321 that biases the valve mechanism 303 in the closed position against the valve mechanism seat 305. The return spring 323 may be pre-stressed by the adjustment sleeve 324.

The upstream valve housing 337 includes an injector driver circuit 311 that actuates the valve mechanism in response to a start of injection (SOI) event. The injector driver circuit 311 may comprise an electromagnetic actuator for actuating the valve mechanism and may comprise a magnetic coil 310 wound onto a coil support 312 which rests against a connection 313 serving as an inner pole 333. The magnetic coil may be supplied with current in two opposite directions and in different amounts depending on the operating conditions. In a direction outward from the central axis 355, the magnetic circuit may be sealed by the outer magnetic component 314. The magnetic coil 310 is energized via a wire 319 by a current that may be supplied via an electrical plug 317.

Fuel is supplied via a central fuel supply 316 at the upstream end 359 of the fuel injector 300 and filtered by a filter element 325 inserted therein. The fuel injector 300 may be sealed from the fuel dispenser line (e.g., fuel rail) by a seal 328 and from the cylinder head (e.g., cylinder 14) by another seal 336.

Specifically, fuel injector 300 may receive a fuel pulse width signal FPW from controller 12 to control fuel injection. Signal FPW manages fuel injection by energizing electromagnetic actuator coil 310 to initiate a start of fuel injection (SOI) from fuel injector 300. Additionally, FPW may determine an end of fuel injection (EOI) from fuel injector 300. Specifically, during fuel injection, pressurized fuel may be supplied to the fuel injector 300 via the inlet 316 from a fuel rail (e.g., the first or second fuel rails 250, 260 in fig. 2), the flow of which is governed by an electromagnetic actuator having a coil 310 coupled to a valve mechanism 303 that lifts from a valve seat 305 to inject fuel into the cylinder 14.

In operation, the return spring 323 acts on the first flange 321 of the valve needle 303 opposite its lifting direction such that the valve opening and closing member 304 is held in sealing contact against the valve seat surface 306. The energizing of the magnetic coils 310 may be performed by supplying a first amount of current through the magnetic coils 310 in a first direction. A first amount of current in a first direction generates a magnetic field that attracts the valve mechanism 303 upward to lift the valve mechanism 303 off the valve seat 305. For example, the magnetic field may move the magnetic armature 320 in a lifting direction against the spring force of the return spring 323. The total lift of the valve mechanism can be defined by the working gap that exists between the connection 313 and the magnetic armature 320 in the rest position. The magnetic armature 320 is also carried along the first flange 321 in the lifting direction. The valve opening and closing member 304 connected to the valve mechanism 303 is lifted off the valve seat surface 306, and the fuel is ejected through the ejection orifice 307.

In the case of a valve member made of permanently magnetized material, a magnetic field is present in the valve member, for example, the magnetic dipole moment of the valve member may extend in the direction of the central axis of the valve member. In this case, the direction of the current supplied to injector driver 311 may be selected such that the magnetic field generated by magnetic coil 310 has a magnetic dipole moment in a direction opposite to the magnetic dipole moment of the valve mechanism, such that the magnetic field generated by magnetic coil 310 attracts the permanently magnetized valve mechanism to lift the valve mechanism from the valve mechanism seat. In this example, the amount of current supplied to the injector driver may be reduced because the magnetic field in the valve mechanism provides additional force to lift the valve mechanism.

In response to the end of the injection event, the first amount of current supplied to injector driver 311 in the first direction is interrupted, and after the magnetic field has sufficiently decayed, magnetic armature 320 drops away from linkage 313 due to the pressure of return spring 323 causing valve mechanism 303 to move in a direction opposite the lift direction. The valve opening and closing member 304 is lowered on the valve seat surface 306, and the fuel injector 300 is closed again.

Fig. 1-3 illustrate exemplary configurations of a fuel system with relative positioning of various components. In at least one example, such elements may be referred to as being in direct contact or directly coupled, respectively, if shown as being in direct contact or directly coupled to each other. Similarly, elements shown as abutting or adjacent to one another may each abut or be adjacent to one another, at least in one example. By way of example, components that are in coplanar contact with each other may be referred to as coplanar contacts. As another example, in at least one example, only elements that are positioned apart from each other with space in between and without other components may be referred to as such.

As discussed herein, a system for a vehicle may include: a fuel system including a pulsed lift pump that supplies fuel from a fuel tank to a low pressure fuel rail; and a set of port fuel injectors that supply fuel from the low pressure fuel rail to a set of cylinders of the engine. The system may also include a controller having computer readable instructions stored on a non-transitory memory that, when executed, cause the controller to command injection of a predetermined amount of the fuel into a cylinder of the set of cylinders via a port fuel injector of the set of port fuel injectors. The controller may store further instructions to determine a fuel injection pressure of the fuel in the fuel rail based on a port fuel injector full open time and/or a fuel injector full close time; and controlling a fuel injection pulse width of a subsequent fuel injection to another engine cylinder based on the fuel injection pressure.

For this system, the set of port fuel injectors may be open-in fuel injectors that include a valve mechanism having an opening rate and a closing rate that are a function of the fuel injection pressure.

For this system, the low pressure fuel rail may not include a pressure sensor.

For this system, the controller may store further instructions to continuously update the fuel injection pressure based on each fuel injector full open time and/or each fuel injector full close time when the engine is operating in a combustion mode.

For this system, the controller may store additional instructions to infer the port fuel injector full open time and/or the fuel injector full close time based on monitored power profiles corresponding to activation and/or deactivation of the fuel injector, respectively.

For this system, the fuel rail may include a pressure sensor, and the controller may store further instructions to indicate degradation of the pressure sensor in response to the fuel injection pressure differing from a monitored fuel injection pressure indicated by the pressure sensor by more than a predetermined threshold, and to control the fuel injection pulse width of the subsequent fuel injection to another cylinder based on the fuel injection pressure in response to the pressure sensor being indicated as degraded.

For this system, the port injector full open time may be independent of the voltage supplied to the port injector.

FIG. 4 illustrates an exemplary high-level method 400 for controlling fuel injectors (e.g., direct fuel injector 166 and/or port fuel injector 170 of FIG. 1). The instructions for performing the method 400 and the remaining methods included herein may be executed by a controller (e.g., the controller 12 in fig. 1) based on instructions stored on a memory of the controller in conjunction with signals received from sensors of the engine system, such as the sensors described above with reference to fig. 1 and 2. According to the methods described below, the controller may employ actuators of an engine (e.g., engine 10 in FIG. 1) and/or a fuel system (e.g., fuel system 8 in FIG. 2) to change the state of a device in the physical world.

At 402, control may determine engine operating conditions. Engine operating conditions may include engine load, engine temperature, engine speed, operator torque demand, and the like. Based on the estimated operating conditions, a plurality of engine parameters may be determined. For example, at 404, a fuel injection schedule may be determined. This may include determining the amount of fuel to deliver to the cylinder (e.g., based on the torque demand) and the injection timing. Further, the fuel injection mode best suited for the current engine operating conditions may be selected. In one example, at high engine loads, Direct Injection (DI) of fuel into an engine cylinder via a direct injector may be selected to take advantage of the charge cooling properties of DI such that the engine cylinder may operate at higher compression ratios without causing undesirable engine knock. If direct injection is selected, the controller may determine whether fuel is delivered as a single injection or split into multiple injections, and further determine whether to deliver one or more injections during the intake stroke and/or the compression stroke. In another example, at lower engine loads and at engine starts (particularly during cold starts), port injection (PFI) of fuel into the intake port of an engine cylinder via a port fuel injector may be selected to reduce particulate matter emissions. If port injection is selected, the controller may determine whether to deliver fuel during a closed intake valve event or an open intake valve event. Other conditions may exist where a portion of the fuel may be delivered to the cylinder via the port injector and the remainder of the fuel is delivered to the cylinder via the direct injector. Determining the fuel injection schedule may further include determining a fuel injector pulse width and a duration between injection pulses for each injector based on estimated engine operating conditions.

At 406, the routine includes determining whether port fuel injection only is requested based on current engine operating parameters. For example, during conditions of low engine load and low engine temperature and engine start, PFI may only be requested. If it is determined that PFI-only is not currently being requested, the routine may include determining whether direct injection-only is requested at 408. DI may be desirable, for example, during high engine loads and/or during conditions of high engine temperatures. If it is determined that only DI is requested, fuel may be injected into the engine via a direct injector (such as direct injector 252 in FIG. 1) at 410. The controller may adjust an injection pulse width of the direct injector to provide fuel via the direct injector according to the determined fueling schedule. In some examples, the pulse width may be determined as a function of fuel injection pressure (e.g., fuel pressure in a corresponding fuel rail). As will be set forth in more detail below, in some examples, fuel injection pressure may be inferred based on an electrical energy profile corresponding to fuel injector activation/deactivation (e.g., de-activation of the fuel injector). It will be appreciated that in the case of a DI only request, the PFI may be interrupted. In the event of an interruption in the PFI, pressure buildup due to, for example, thermal expansion of fuel in a fuel rail supplying fuel to the PFI (e.g., second fuel rail 260 in fig. 2) may be vented via pressure relief valve 242.

If it is determined that PFI only or DI only is not desired for fueling, then at 412, the routine may determine whether both DI and PFI are requested for fuel injection. If it is determined that both direct and port injection have been requested, then at 414, the controller may send a signal to an actuator coupled to each of the direct and port injectors to initiate fueling based on the determined fueling plan. Each injector may deliver a portion of the total fuel injection for combustion. The distribution and/or relative amount of fuel delivered from each injector may vary based on operating conditions (such as engine load, knock, exhaust temperature, etc.). If both DI and PFI are not requested at 412, it may be appreciated that the vehicle may be operating in an electric-only operating mode, and such operating parameters may be maintained. The fuel injection pulse width for each injector type may be controlled as a function of fuel injection pressure in the corresponding fuel rail, and as discussed above, in some examples, fuel injection pressure may be inferred based on an electrical energy profile of individual fuel injector activation/deactivation, which corresponds to opening time and/or closing time parameters as will be set forth below.

Returning to 406, if it is determined that only PFI is desired, at 416, the controller may command the determined pulse width to a port injector (such as port injector 170 in fig. 1) to initiate fuel injection. Additionally, it is understood that the controller may deactivate the direct injector. In the event of a DI outage, pressure buildup due to, for example, thermal expansion of fuel in a fuel rail supplying fuel to the DI (e.g., first fuel rail 250 in fig. 2) may be vented via pump relief valve 272.

As discussed above, controlling the fuel injector to achieve the desired engine operating conditions may include determining a fuel injector pulse width. The fuel injector pulse width determines how much fuel is injected into the corresponding engine cylinder and is a function of the fuel rail pressure. In other words, the basic concept of fuel injection is that the injection pressure is known, and then the required opening time of the injector can be calculated based on the injection pressure to achieve the desired injection quantity for each injection event. In one example, the fuel rail pressure may be determined via a pressure sensor (e.g., first rail pressure sensor 248 or second rail pressure sensor 258 in fig. 2). Additionally or alternatively, the fuel rail pressure may be determined according to known pressure regulator settings.

As noted above, it may be desirable to infer fuel rail pressure by another means. For example, a pressure sensor may fail in some cases. In other examples, inferring the fuel rail pressure by another means may enable diagnostics to be performed on existing fuel rail pressure sensors. In some examples, being able to infer fuel rail pressure by another means may enable the ability to control fuel injection without relying on such a sensor, which may reduce complexity and cost. In a similar manner, in some examples, being able to infer fuel rail pressure by another means may enable the ability to avoid pressure regulator aspects of the fuel delivery system, which may reduce complexity and cost.

It is recognized herein that the fuel injector itself may be used as the pressure measurement device. The fuel injector may be of the inward opening type (see fuel injector 300 in fig. 3) or outward opening type (not shown). In the case of an open-ended fuel injector, opening the injector electrically must overcome not only the biasing force of a spring (e.g., return spring 323 in fig. 3), but also the fuel pressure acting on the pintle (see valve mechanism 303 in fig. 3) of the fuel injector. Thus, a higher fuel pressure may result in a longer opening time as compared to a lower fuel pressure with respect to opening the fuel injector. In a similar manner, higher fuel pressures may result in faster closing time parameters than lower fuel pressures. Accordingly, fuel pressure may be inferred based on fuel injector open time and/or close time measurements, as will be set forth further below.

Turning to fig. 5A, an exemplary circuit 500 that may be used in some examples to actuate a fuel injector is shown. Specifically, fuel injector 505 (e.g., the same as fuel injector 166 or the same as fuel injector 170) may be actuated via a controller (e.g., controller 12 in fig. 1), via a circuit 500 including a low side power switch 508 in parallel with a zener diode 510. It will be appreciated that the zener diode 510 may protect the circuit 500 from over-voltages due to self-induction, which may occur, for example, when the energization of the injector coil is stopped.

In a de-energized mode with a no current coil (e.g., coil 310 in fig. 3), the valve mechanism (e.g., valve mechanism 303 in fig. 3) may be seated against a valve seat (e.g., valve mechanism seat 305 in fig. 3) by the force of a spring (e.g., return spring 323 in fig. 3) and the fuel pressure in the fuel rail. When the power supply 511 is commanded on, the coil may be energized and an electromagnetic field may be present, thus unseating the valve mechanism from the valve seat and enabling fuel to be injected to the engine cylinder. Deactivating the activation current may again cause the injector to close. As will be explained in more detail below, measuring the voltage at the first circuit location 512 and measuring the current at the second circuit location 513 may enable a determination to be made as to when the fuel injector is fully open and fully closed.

Turning now to FIG. 5B, an exemplary illustration 545 graphically depicts the relationship between actuation pulse (graph 550), current (graph 552), fuel injection valve lift (graph 554), and amount of fuel injected to an engine cylinder (graph 556). At time t0, no actuation voltage is supplied to the fuel injector (graph 550), and thus no current is supplied (graph 552). Thus, the valve has not opened at all (0 lift, plot 554) and no fuel is injected to the corresponding engine cylinder (plot 556).

At time t1, the fuel injector is actuated (e.g., a voltage is supplied to the fuel injector). However, it takes some time before the valve mechanism reaches full lift. The delay time (e.g., the time period between times t1 and t2) may depend on a number of variables, including but not limited to actuation voltage, fuel pressure, manifold pressure, temperature, injector spring force, etc. the inflection point in the current at t2 may be understood to indicate the time at which the valve mechanism has reached full lift. Thus, it can be appreciated that by monitoring the current (e.g., the current at the second circuit location 513 in fig. 5A), the off time can be inferred. As described above and as will be explained further below, the opening time may be a function of fuel pressure, and thus fuel pressure may be inferred based on the current trace (where full opening corresponds to an inflection point in the current trace, as shown at time t 2).

The effect that can be observed with injector closing is similar to that observed with injector opening. For example, at time t3, the supply of voltage to the fuel injector is stopped. The current is correspondingly reduced between time t3 and t4, and the valve closes. Although the current decays faster than the valve becomes fully closed in this exemplary illustration 545, in other examples, the current may decay in a manner that corresponds more closely to the valve closing. More specifically, when the valve is no longer actuated at time t3, the induced magnetic field in the coil takes some time to dissipate, so the valve does not close immediately when the supply of voltage is interrupted.

In the case of energizing a fuel injector via the type of circuit depicted in FIG. 5A, it can be appreciated that a monitored voltage signal (e.g., at the first circuit location 512 in FIG. 5A) can be used to infer when the valve is fully closed. Further, as discussed above, the monitored current signal (e.g., at the second circuit position 513 in fig. 5A) can be used to infer when the valve is fully open. Turning to fig. 5C, an exemplary illustration 570 graphically depicts how current may be used to infer when a valve is fully open and how voltage may be used to infer when a valve is fully closed. Thus, plot 570 shows the relationship between valve lift (plot 580), current (plot 582), and voltage (plot 584).

At time t0, it may be appreciated that no voltage (graph 584) is applied to the fuel injector and, therefore, no valve lift (graph 580) is present because no current (graph 582) is provided to the fuel injector coil. At time t1, a voltage pulse is applied to actuate the opening of the fuel injector. Between time t1 and t2, the current increases, and at time t2, an inflection point in the current trace (reference arrow 586) indicates that the valve is fully open.

At time t3, the voltage command is interrupted. The voltage trace between times t 3-t 4 may be understood as a result of the extinguishing voltage of the zener diode (e.g., zener diode 510 in fig. 5A). Specifically, when the low-side switch (e.g., low-side power switch 508 in fig. 5A) is open, the current through the coil of the injector collapses. However, due to electromagnetic induction, there is no step in the current and a negative voltage is generated across the injector. The negative voltage is limited by the zener voltage. For voltages greater than the zener voltage, breakdown of the diode occurs. After the breakdown is over, no more current flows through the fuel injector. The remaining energy stored in the coil is dissipated by eddy currents in the metal core. An induced voltage can be observed at the terminals of the coil. Thus, the change in slope of the voltage at time t4 (reference arrow 587) indicates that the fuel injector is fully closed. It will be appreciated that for injector opening, an inflection point in the current occurs (see arrow 586) when the valve mechanism reaches top dead center of the fuel injector. The inflection point is the result of a rapid change in needle speed and is the result of a rapid change in the inductance of the solenoid. For injector closing, the slope change again occurs due to the rapid change in the inductance of the solenoid (see arrow 587).

Turning to fig. 5D, an exemplary plot 590 is depicted showing current (graph 591) of a peak-hold driver (e.g., low impedance or current regulated) over time. In particular, this peak-hold driver may be used with fuel injectors having low resistance coils that require more current to open. Thus, a switching mechanism is included in the circuit that reduces the current to a lower level after the injector opens. Once the injector is open, much less current is required to keep it open. Based on fig. 5D, it can be appreciated that the time range between times t1 to t2 represents the fuel injector full open time (reference line 592), and the time range between times t3 to t4 represents the injector full close time (reference line 593). As depicted, peak current occurs between times t 2-t 3, followed by switching to a lower level between times t 2-t 3.

Turning to fig. 5E, an exemplary plot 595 is depicted, which shows the current (plot 596) of a saturated driver system (e.g., high impedance) over time. In particular, an injector used in a saturation driver system may require a high resistance valve across its coil to enable the injector to operate at low current levels. Based on fig. 5E, it can be appreciated that the time range between times t1 to t2 represents a fuel injector full open time (reference line 597), and the time range between times t3 to t4 represents an injector full close time (reference line 598). As depicted, the current saturates between time t2 and t 3.

As discussed above, it is recognized herein that the fuel injector full open time and the fuel injector full close time may be affected by the fuel pressure acting on the valve mechanism (e.g., valve mechanism 303 in fig. 3), and that by using the strategies outlined above (e.g., monitoring the power profile of the fuel injector in response to injector activation/deactivation), the fuel pressure may be inferred based on the inferred open time determination and close time determination. Thus, turning to FIG. 6A, exemplary diagram 600 graphically depicts open time on the y-axis and fuel pressure on the x-axis (see inset 601). As evidenced by the graph 605, the opening time monotonically increases as the fuel pressure increases, and the opening time monotonically decreases as the fuel pressure decreases. Accordingly, it is recognized herein that the open time determination may be used to infer fuel pressure.

Turning to FIG. 6B, an exemplary plot 650 graphically depicts closing time on the y-axis and fuel pressure on the x-axis (see inset 601). As evidenced by graph 655, the closing time decreases monotonically as the fuel pressure increases (e.g., increasing fuel pressure forces the valve mechanism to close faster than less fuel pressure), and the closing time increases monotonically as the fuel pressure decreases (e.g., the valve mechanism closes slower when less pressure forces the valve mechanism to close). Accordingly, it is recognized herein that the closing time determination may be used to infer fuel pressure.

In some examples, both the opening time and the closing time may be used in combination to infer fuel pressure. For example, an open time determination may be used to infer a first fuel pressure, and a closed time determination may be used to infer a second fuel pressure. For example, the first fuel pressure and the second fuel pressure may be averaged together to derive the determined fuel pressure.

In some examples, any number of open time determinations and/or close time determinations for a particular fuel injector may be used to infer fuel pressure. For example, to obtain a higher confidence fuel pressure determination, multiple measurements of opening time and/or closing time may be obtained and averaged together to infer fuel pressure.

It will be appreciated that the determination of fuel pressure may not be limited to one fuel injector opening time and/or closing time. For example, in some examples, the opening times and/or closing times of multiple fuel injectors opening and/or closing may be used in combination to infer fuel pressure without departing from the scope of the present disclosure.

It is recognized herein that variables such as temperature and injector spring force (in addition to fuel pressure) may affect the opening and closing time determinations. Thus, it can be appreciated that in order to infer fuel pressure from the open time determination and/or the close time determination, it may be necessary to compensate for variables that otherwise affect the open time and/or the close time. For example, such variables may be considered by calibrating (e.g., off-line calibration) individual fuel injectors at multiple fuel pressures. For example, calibration may involve actual measurement and/or experimental modeling methods. By performing such calibration work, one or more look-up tables may be stored in the controller, which may enable the controller to infer fuel pressure from the opening time determination and/or closing time determination of each individual fuel injector. It will be appreciated that in some examples, the voltage itself may affect the opening/closing time of a particular fuel injector. However, it is recognized herein that the effects of voltage may be avoided, for example, by using a DI ejector driver for both DI and PFI, as the DI ejector driver may eliminate the dependency of opening/closing on battery voltage.

It is further recognized herein that in some examples, it may be inferred that a particular fuel injector is not functioning as expected or expected (e.g., due to a blockage, an at least partially normally open fault, a normally closed fault, etc.) based on inferred pressure measurements as a function of opening time and/or closing time. As one example, a particular fuel injector opening time may reflect a fuel pressure that is substantially different (e.g., greater than 5% different, or greater than 10% different) from the fuel pressure determined by a plurality (e.g., 3) of other fuel injectors. In this example, it may be inferred that the "correct" fuel pressure is likely to be the fuel pressure determined via multiple fuel injectors, and that the particular fuel injector associated with the different reported fuel pressures may degrade at least to some extent (e.g., a blockage, a normally open fault, a normally closed fault, etc.). As will be discussed in further detail below, in some examples, this determination may be validated via pressure as monitored via a pressure sensor in the fuel rail, or may be based on a pressure relief point.

Turning now to FIG. 7, an advanced exemplary method 700 for inferring fuel rail pressure based on fuel injector on-time determinations and/or off-time determinations as inferred from fuel injector power profiles upon activation/deactivation is depicted. The method 700 will be described with reference to the systems described herein and shown in fig. 1-3, but it should be understood that similar methods may be applied to other systems without departing from the scope of the present disclosure. The method 700 may be performed by a controller (such as the controller 12 in fig. 1) and may be stored as executable instructions in a non-transitory memory at the controller. The instructions for performing method 700 and the remaining methods included herein may be performed by a controller based on instructions stored on a memory of the controller in conjunction with signals received from sensors of a vehicle system, such as the sensors described above with reference to fig. 1 and 2. The controller may employ vehicle system actuators, such as a fuel pump (e.g., fuel pump 212 in FIG. 2), one or more port fuel injectors (e.g., port fuel injector 170 in FIG. 1), one or more direct fuel injectors (e.g., direct fuel injector 166 in FIG. 1, etc.) to change the state of devices in the physical world according to the methods described below.

Method 700 begins at 705 and includes indicating whether a condition for commanding opening of a particular fuel injector is satisfied. With respect to the method of FIG. 7, it may be appreciated that the fuel injector may be a direct fuel injector (e.g., DI 166 in FIG. 1) or a port fuel injector (e.g., PFI 170 in FIG. 1). For example, satisfying the condition for commanding a particular fuel injector to open may include an indication of: the cylinder receiving fuel from a particular fuel injector is in the intake stroke or compression stroke in which delivery of fuel to the cylinder is requested. If the condition is not satisfied at 705, method 700 proceeds to 710 where the current injector state may be maintained. For example, if the injector is already open, the injector may be maintained in its current state. If the injector is closed, the injector may remain closed. Method 700 may then end.

Returning to 705, in response to an indication that the condition for fuel injector opening is satisfied, method 700 proceeds to 715. At 715, method 700 includes commanding opening of the fuel injector. Commanding opening of the fuel injector may be understood as including supplying a voltage to the fuel injector that generates a current in a coil (e.g., coil 310 in fig. 3) of the fuel injector. Method 700 proceeds to 720 where the fuel injector is commanded open at 715. At 720, method 700 includes determining an opening time (e.g., a full opening time) of the fuel injector based on the monitored power profile of the fuel injector circuit. Specifically, as discussed above with respect to fig. 5A-5E, an inflection point in the current trace (see, e.g., time t2 in fig. 5C) may be used to infer when the fuel injector is fully open, or in other words, when the valve lift is at its maximum 100% lift capability. Thus, the time between when the valve is initially actuated and the time before the inflection point in the indicated current trace may reflect the opening time of the fuel injector. Where the open time is determined at 720, method 700 proceeds to 725. At 725, the method 700 includes storing the results in the controller.

Advancing to 730, method 700 includes indicating whether a condition for commanding closing of the fuel injector is satisfied. For example, a pulse width for controlling a fuel injector may be determined before initiating a command to open the fuel injector, and thus the determined pulse width may determine when to command to close (e.g., deactivate) the fuel injector after activating the fuel injector. If the conditions for fuel injector closing are not met at 730, the fuel injector may remain open. Alternatively, method 700 proceeds to 740 in response to a condition for closing the fuel injector being met. At 735, method 700 includes commanding closing of the fuel injector by removing voltage supplied to a circuit controlling the fuel injector. In other words, at 735, method 700 includes deactivating the fuel injector such that the fuel injector is closed.

Method 700 proceeds to 740 in response to deactivation of the fuel injector. At 740, method 700 includes determining a closing time based on an electrical energy profile of the injector occurring when the fuel injector transitions from the fully open state to the fully closed state. As one example, the power profile may be related to voltage, as discussed above with respect to fig. 5C. As another example, the power profile may be related to current, as discussed above with respect to fig. 5D-5E.

Where the off time is determined at 740, method 700 proceeds to 745 where the results are stored in the controller. At 750, method 700 determines whether there is a request for additional data from one or more other fuel injectors. For example, as described above, there may be the following: opening time determinations and/or closing time determinations are made for any number of different fuel injectors so that the controller may average and/or otherwise compare the inferred opening time determinations and/or closing time determinations to accurately predict or infer fuel pressure. Thus, if there is an additional request for data from one or more other fuel injectors at 750, method 700 may return to step 705, where it may be determined whether the condition for the next fuel injector to be commanded on is satisfied, and if so, method 700 may proceed again as discussed above.

Returning to 750, method 700 proceeds to 755 in response to a determination that only one fuel injector open time and/or close time is requested, or in response to data from a predetermined number of fuel injectors having been acquired. At 755, method 700 includes inferring a fuel rail pressure based on a measured open time and/or a measured close time for each injector for which data has been acquired. Specifically, as discussed above with respect to fig. 6A-6B, fuel pressure may be inferred based on the opening time determination and/or closing time determination of a particular fuel injector and/or a plurality of fuel injectors. The inference of fuel pressure may include the controller referencing one or more lookup tables that enable the controller to accurately infer fuel pressure based on the open time determination and/or the close time determination.

Where fuel pressure is determined, method 700 proceeds to 760, where method 700 includes pulse width determination using the inferred fuel rail pressure to control the appropriate fuel injector or injectors as discussed above with respect to FIG. 4 and/or for related diagnostics, as will be discussed below with respect to FIG. 8. Method 700 may then end.

Accordingly, as discussed herein, a method may include commanding injection of a predetermined amount of fuel into a cylinder of an engine via a fuel injector. In response to the command, the method may include monitoring an electrical energy profile associated with the fuel injector. The method may include inferring a fuel injection pressure based on the electrical energy profile and controlling a follow-on fuel injection based on the inferred fuel injection pressure.

With this approach, the fuel to be injected into the cylinder of the engine may be contained in a fuel rail, wherein the fuel rail may not include a pressure sensor for measuring the fuel injection pressure. The fuel rail may be a low pressure fuel rail and the fuel injector may be a port fuel injector. Alternatively, the fuel rail may be a high pressure fuel rail and the fuel injectors may be direct fuel injectors.

For this approach, the fuel injector may be an open-in configuration fuel injector.

With this method, controlling the subsequent fuel injection may include controlling a fuel injection pulse width of a next fuel injection based on an ignition sequence of the engine.

For this method, the method may further include determining a fuel injector full open time based on the electrical energy profile, and may include inferring the fuel injection pressure based on the fuel injector full open time.

For this method, the method may further include determining a fuel injector full close time based on the electrical energy profile, and inferring the fuel injection pressure based on the fuel injector full close time.

It will be appreciated that in some examples, the fuel pressure inferred via the method of FIG. 7 may be used strictly to control the pulse width of individual fuel injectors without the inclusion of a pressure sensor in the fuel rail that supplies fuel to a particular individual fuel injector. In other words, in the case where the fuel pressure is determined consistently or periodically based on injector opening time determinations and/or injector closing time determinations, reliance on this fuel rail pressure sensor may be avoided. In other examples where the fuel rail does include a pressure sensor, it will be appreciated that the fuel injector pulse width may be controlled in dependence on the fuel pressure determination as discussed with respect to the method of FIG. 7 where it is inferred that the pressure sensor used to monitor the fuel rail pressure has degraded.

Turning now to fig. 8, an advanced exemplary method 800 for determining whether a pressure sensor (e.g., the second fuel rail pressure sensor 258 in fig. 2) used to monitor pressure in a fuel rail (e.g., the second fuel rail 260 in fig. 2) is functioning as desired or is inferred to be somewhat degraded is depicted. Briefly, the method may include inferring a fuel rail pressure based on an open time determination and/or a close time determination of one or more fuel injectors, and then using the inferred fuel rail pressure as a relevant means for inferring whether the pressure sensor exhibits degraded function.

The method 800 may be performed by a controller (such as the controller 12 in fig. 1) and may be stored as executable instructions in a non-transitory memory at the controller. The instructions for performing method 800 and the remaining methods included herein may be performed by the controller based on instructions stored on a memory of the controller in conjunction with signals received from sensors of a vehicle system, such as the sensors described above with reference to fig. 1 and 2. The controller may employ vehicle system actuators, such as a fuel pump (e.g., fuel pump 212 in FIG. 2), one or more port fuel injectors (e.g., port fuel injector 170 in FIG. 1), one or more direct fuel injectors (e.g., direct fuel injector 166 in FIG. 1, etc.) to change the state of devices in the physical world according to the methods described below.

Method 800 begins at 805 and includes measuring fuel pressure via the method of FIG. 7. Where fuel pressure is inferred based on the method of FIG. 7, method 800 proceeds to 810. At 810, method 800 includes comparing the inferred fuel pressure determined via the method of FIG. 7 to the fuel pressure measured via the pressure sensor. The measured fuel pressure may correspond to a single pressure measurement, or may represent an average of a predetermined number of pressure measurements. The comparison may be performed by the controller based on instructions stored in a non-transitory memory.

At 815, method 800 includes determining whether the inferred fuel pressure differs from the measured fuel pressure by more than a predetermined threshold. The predetermined threshold may represent a difference of 5% or more, 10% or more, 15% or more, 20% or more, or the like. For example, if the inferred fuel pressure is greater than the measured fuel pressure by more than 10%, it may be inferred that the inferred pressure differs from the measured pressure by more than a predetermined threshold.

If the inferred fuel pressure differs from the measured fuel pressure within a predetermined threshold at 815, method 800 proceeds to 820. At 820, method 800 includes indicating that a pressure sensor used to measure fuel pressure is functioning as desired or expected. The results may be stored, for example, in the controller. Proceeding to 825, method 800 includes controlling a fuel injector pulse width based on an output from the pressure sensor (e.g., according to the method of fig. 4). In other words, in a vehicle system that includes a pressure sensor in the fuel rail, the pressure sensor may be relied upon to control the fuel injector pulse width as long as the pressure sensor is inferred to function as desired or expected. Method 800 may then end. Although the method 800 is depicted as ending, it is to be appreciated that the method 800 can be performed periodically (e.g., periodically, at predetermined intervals). For example, although not explicitly shown, it is understood that method 800 may be initiated in response to an indication that the pressure sensor may be operating abnormally (e.g., engine lag or other degraded engine operation), after one or more of a predetermined duration of time has elapsed since a previous pressure sensor diagnosis was made, after a predetermined number of miles has been traveled since a previous pressure sensor diagnosis was made, and/or the like.

Returning to 815, where controller determines that the inferred fuel pressure differs from the measured fuel pressure by more than a predetermined threshold, method 800 proceeds to 830. At 830, method 800 includes indicating a pressure sensor degradation. The results may be stored, for example, in the controller. It will be appreciated that, in order to infer that the pressure sensor is degraded (and not degraded), the controller may have to be able to conclusively determine that the inferred pressure based on the fuel injector opening time determination and/or closing time determination is accurate and does not reflect some aspect of, for example, degraded fuel injector function. As one example, the controller may determine that the inferred fuel pressure is accurate when multiple inferred fuel pressure determinations from different fuel injectors are all consistent. For example, if it is determined that four different fuel pressure inferences corresponding to four different fuel injectors are in situations where the fuel pressures are expected to be substantially similar (e.g., differing by less than 5%, differing by less than 2%, differing by less than 1%), the controller may determine that the inferred fuel pressures accurately reflect the fuel pressures. A greater or lesser number of inferred pressure measurements may be used without departing from the scope of the present disclosure.

In response to an indication of pressure sensor degradation, method 800 proceeds to 835. At 835, method 800 includes controlling a fuel injector pulse width based on the inferred pressure, where the inferred pressure is determined based on an open time determination and/or a close time determination of one or more individual fuel injectors, as previously discussed. In other words, because the pressure sensor is indicated as degraded, the fuel injector pulse width determination may instead be subsequently made to rely on the method used to infer fuel pressure in order to control fuel injection according to the method of FIG. 4 discussed above.

It will be appreciated that the method discussed with respect to fig. 8 may be applied to a pressure sensor monitoring the pressure in a fuel rail supplying fuel to the PFI and/or to a different pressure sensor monitoring the pressure in a different fuel rail supplying fuel to the DI. For example, pressure may be inferred via the method of FIG. 7 for a fuel rail supplying fuel to a PFI, such that a pressure sensor monitoring fuel pressure in the fuel rail supplying fuel to the PFI may be diagnosed according to the method of FIG. 8. In another example, pressure may be inferred via the method of fig. 7 for a fuel rail supplying fuel to the DI, such that a pressure sensor monitoring fuel pressure in the fuel rail supplying fuel to the DI may be diagnosed according to the method of fig. 8.

Thus, as discussed herein, a method may include commanding a fuel injector to deliver a predetermined amount of fuel contained in a fuel rail to a cylinder of an engine. The method may further include determining a first duration from when the fuel injector is actuated open to when the fuel injector is fully open and/or determining a second duration from when the fuel injector is actuated closed to when the fuel injector is fully closed. The method may further include indicating a presence or absence of degradation associated with a pressure sensor that determines a measured fuel injection pressure in the fuel rail based on the first duration and/or the second duration.

For this method, the method may further include: determining an inferred fuel injection pressure based on the first duration and/or the second duration; indicating that there is no degradation of the pressure sensor when the inferred fuel injection pressure is within a predetermined threshold of the measured fuel injection pressure; and indicating a degradation of the pressure sensor when the inferred fuel injection pressure is not within the predetermined threshold of the measured fuel injection pressure. In this example, the method may further include controlling a fuel injection parameter based on the measured fuel injection pressure in response to an absence of an indication of degradation associated with the pressure sensor; and controlling the fuel injection parameter based on the inferred fuel injection pressure in response to an indication of a presence of degradation associated with the pressure sensor.

For this method, the first duration and the second duration may be inferred based on a monitored power profile associated with the fuel injector in response to actuation of opening and actuation of closing the fuel injector, respectively.

For this approach, the fuel rail may be a high pressure fuel rail or a low pressure fuel rail, and the fuel injector may be a direct fuel injector or a port fuel injector, respectively.

As described above, with the ability to infer fuel pressure based on-time determinations and/or off-time determinations based on an electrical energy profile of fuel injector activation/deactivation, reliance on one or more fuel rail pressure sensors of a fuel system including a pulsed lift pump (e.g., fuel pump 212 in fig. 2) may be avoided. In this example, correlating the inferred fuel pressure with the modeled pressure may enable a determination of whether a particular aspect of the overall fuel system is degraded.

Turning to FIG. 9, an advanced exemplary method 900 depicts a method for correlating an inferred fuel pressure measurement with a modeled fuel pressure to infer the presence/absence of fuel system degradation. Method 900 involves evaluating a port fuel injector in a single fuel dual injector of a dual fuel rail per cylinder system. Specifically, the fuel rail pressure in both the high pressure fuel rail (e.g., first fuel rail 250 in FIG. 2) and the low pressure fuel rail (e.g., second fuel rail 260 in FIG. 2) may be raised to a predetermined level at which pumping may be suspended and fuel may be injected into a single cylinder via PFI in order to detect a pressure drop in the low pressure rail due to injection. Other cylinders of the engine may continue to be fueled by their respective DI and the port injectors may be used one at a time to perform the diagnostics, thereby maintaining engine efficiency. Each port injector may be diagnosed sequentially. It will be appreciated that the diagnostic routine of FIG. 9 may be performed to diagnose a single cylinder at a time (as shown) or a bank of cylinders at a time.

The method 900 may be performed by a controller (such as the controller 12 in fig. 1) and may be stored as executable instructions in a non-transitory memory at the controller. The instructions for performing method 900 and the remaining methods included herein may be performed by a controller based on instructions stored on a memory of the controller in conjunction with signals received from sensors of a vehicle system, such as the sensors described above with reference to fig. 1 and 2. The controller may employ vehicle system actuators, such as a lift pump (e.g., fuel pump 212 in FIG. 2), one or more port fuel injectors (e.g., port fuel injector 170 in FIG. 1), one or more direct fuel injectors (e.g., direct fuel injector 166 in FIG. 1), a high pressure fuel pump (e.g., fuel pump 214 in FIG. 2), etc., to change the state of devices in the physical world according to the methods described below.

Method 900 begins at 905 and includes indicating whether a condition for relating the inferred fuel pressure to the modeled fuel pressure is satisfied. The conditions of such a correlation method may be satisfied after one or more of a predetermined number of miles traveled since the correlation method was last performed, after a predetermined duration of time has elapsed since the correlation method was last performed, in response to an indication that there may be fuel system degradation (e.g., an indication of engine lag, stall, engine surge, etc.), and so forth. If, at 905, it is indicated that the condition is not met, method 900 proceeds to 910 where the current operating conditions are maintained. For example, the current fuel injection schedule may be maintained without performing the diagnostic method of FIG. 9. Method 900 may then end.

Returning to 905, in response to an indication that the conditions for performing the diagnostic method of fig. 9 are satisfied, method 900 may proceed to 915. At 915, method 900 includes selecting a particular engine cylinder for fuel injector diagnostics. The particular cylinder and fuel injector pair may be selected according to a predetermined order, or may be selected based on some indication (e.g., misfire) that there may be some problem with the fuel injection of the particular cylinder.

Method 900 proceeds to 920 where a cylinder and fuel injector pair is selected. At 920, method 900 includes operating a lift pump (e.g., pump 212 in fig. 2) to raise a pressure in a low pressure fuel rail (e.g., second fuel rail 260 in fig. 2) to a first threshold pressure (e.g., a maximum pressure or a pressure relief point). For example, the lift pump may be controlled such that the fuel pressure within the low pressure fuel rail is at a first threshold pressure.

Proceeding to 925, the high-pressure pump (e.g., HPP214 in FIG. 2) may be operated to increase the pressure within the high-pressure fuel rail to a second threshold pressure. As discussed, DI can operate at higher pressures than PFI. Thus, the second threshold pressure may be higher than the first threshold pressure. By raising the pressure in the entire fuel system prior to a calibration event, sufficient fuel is available for proper metering by the injector and multiple injection events.

Thus, unlike a lift pump system in which fuel is pressurized in a low pressure fuel rail due to a flexible conduit, a high pressure pump system is rigid. This is because the fuel pressure storage in the high pressure system is due to the bulk modulus of the fuel. Thus, by raising the pressure in the high-pressure fuel rail to a sufficiently high pressure (e.g., at a maximum allowable level or above a threshold pressure), the high-pressure pump may be momentarily turned off even when the direct injectors are supplying fuel to the engine. Because port injector diagnostics require disabling the lift pump, and because the lift pump lifts fuel to further pressurize the high pressure pump by sufficiently pressurizing the high pressure fuel rail, both the high pressure pump and the lift pump may be disabled during port injector diagnostics without affecting engine fuel delivery via the direct injector.

Proceeding to 930, method 900 includes deactivating the lift pump and the high pressure pump (e.g., first deactivating the lift pump, then deactivating the high pressure pump) simultaneously or sequentially. Thus, the first amount of fuel may be present in the low pressure fuel rail and the second amount of fuel may be present in the high pressure fuel rail. After suspending fuel pumping, at 935, method 900 includes injecting fuel via the direct injector to a cylinder not selected for injector diagnostics. Alternatively, at 940, method 900 includes injecting fuel via a port fuel injector corresponding to the selected cylinder for a predetermined number of injections when the condition for providing fuel to the selected cylinder is satisfied. The satisfaction of the conditions for providing fuel to the selected cylinders via port fuel injection (and to the remaining cylinders via direct injection) may be based, for example, on the firing order of the engine.

Proceeding to 945, method 900 includes inferring fuel pressure in the low-pressure fuel rail based on the method discussed above in FIG. 7 for each fuel injection to the selected cylinder. In other words, fuel injector opening and/or closing times may be inferred depending on one or more of the electrical energy profiles discussed above, where the opening and/or closing time determinations may in turn be used to infer fuel pressure as discussed. For example, the number of injections for a selected cylinder may be preselected, and may be a function of how many data points are expected to correlate the inferred fuel pressure change with the modeled fuel pressure change.

Proceeding to 950, method 900 includes determining whether a predetermined number of injections have been completed. If not, method 900 returns to 940 where one or more fuel injections to the selected cylinder continue. Alternatively, method 900 proceeds to 955 in response to an indication that a predetermined number of shots have been completed. At 955, method 900 includes storing results of the inferred fuel pressure at each injection in the controller. It will be appreciated that the inferred fuel pressure at each injection may correspond to a pressure drop, as each fuel injection may be expected to further reduce the pressure in the corresponding low-pressure fuel rail. Continuing to 960, method 900 includes optionally repeating steps 915 through 955 for any additional fuel injectors for which controller requests diagnostics. As discussed, data points acquired for each fuel injector may be similarly stored in the controller.

Advancing to 965, method 900 includes comparing the determined pressure change corresponding to the data point for each individual fuel injector/selected cylinder pair to the modeled pressure change. It will be appreciated that the modeled pressure change may be an expected pressure change in the fuel rail given a particular fuel injector pulse width, a predetermined number of injections, an initial fuel rail pressure, and other variables (including but not limited to fuel temperature in the fuel rail).

Advancing to 970, method 900 includes inferring a presence or absence of degradation based on a comparison of the determined pressure change to the modeled pressure change. For example, if the determined pressure changes differ by more than a predetermined threshold difference (e.g., by greater than 5%, by greater than 10%, by greater than 15%, by greater than 20%, etc.), then it may be determined that degradation is present. In some examples, it may be determined that the degradation is due to degradation of a particular fuel injector, as discussed above with respect to FIG. 11A. In other examples, the degradation may be determined to be degradation of a different type (e.g., a pressure relief mechanism associated with a PFI fuel rail, etc., such as the pressure relief valve 242 in fig. 2) or other check valve (e.g., the valve 244 in fig. 2), as will be discussed below with respect to fig. 11B. Alternatively, if the determined pressure change is within a predetermined threshold difference of the modeled pressure change, it may be determined that the component part associated with the PFI is functioning as desired or expected. Whether the presence or absence of degradation is inferred, the results may be stored in the controller.

Proceeding to 975, method 900 includes updating the operating parameters. Where no degradation is indicated at 970, method 900 may include updating a plan for performing the diagnostic routine of FIG. 9 at 975. For example, based on the pass results, another diagnostic routine may be scheduled for a future time (or after a particular number of miles have been driven since the currently performed diagnosis).

Alternatively, where the presence of degradation is indicated at 970, method 900 may include taking mitigating action in response to the degradation at 975. As one example, the mitigating action may include commanding the lift pump to drive the fuel rail pressure to its known pressure relief point for future fuel injection events of the PFI. Additionally or alternatively, the mitigating action may include setting a flag in a controller and/or setting a fault indicator in a vehicle dashboard to alert a vehicle operator of a request to service the vehicle. In the event that a particular fuel injector is determined to itself exhibit degraded functional operation, then in some examples, the fuel injection pulse width of the particular injector may be adjusted accordingly to compensate for the determined degraded function. In other examples where it is determined that a particular fuel injector exhibits degraded functionality, the mitigating action may include avoiding use of the injector where possible, such as compensation via direct fuel injection. Method 900 may then end.

Turning to fig. 10A-10B, fig. 10A depicts an exemplary map 1000 corresponding to the method of fig. 9, showing fuel injection timing plotted on the y-axis and cylinder number plotted on the x-axis. The depicted example is for a four cylinder engine, where each cylinder includes a direct injector and a port injector. The top graph 1002 represents the firing sequence of the direct injector, and each portion of the fuel injection via the direct injector is depicted by a dashed box. The bottom graph 1004 of FIG. 10A represents the firing sequence of the port injector, and each portion of port injected fuel is shown as a diagonally striped box. Line 1003 represents the beginning of the port injector calibration sequence corresponding to time t1 of map 1010 of FIG. 10B. Line 1005 represents a timing corresponding to time t2 of map 1010 of fig. 10B. Graph 1012 shows the variation of fuel rail pressure within a low pressure fuel rail (e.g., second fuel rail 260 of FIG. 2) when a port injector is fueling a single cylinder during calibration. Graph 1014 depicts a change in fuel rail pressure within a high pressure fuel rail (e.g., first fuel rail 250 in FIG. 2) when a plurality of direct injectors are fueling the remaining three cylinders.

Before time t1 represented by line 1003 in FIG. 10A, during engine operation when the calibration process in FIG. 9 is not in progress, fuel may be provided to each cylinder of the engine via both PFI and DI, and the fuel pressure in both fuel rails may be maintained at the initial operating pressure. At line 1003, a port injector calibration sequence may begin for the port injector supplying fuel to cylinder 1 based on the conditions for performing the calibration diagnostic of FIG. 9 being met. During a calibration event, cylinder 1 may receive exclusively port injected fuel, while cylinders 2, 3, and 4 may receive directly injected fuel.

As shown by the map 1010 of fig. 10B, the fuel rail pressure may increase to a threshold level in each of the two fuel rails before the calibration event at time t1 begins. The pressure in the low-pressure fuel rail coupled to the port injector may increase from an initial level PI _ PI to an upper threshold level PI _ Po. Similarly, the pressure in the high-pressure fuel rail coupled to the direct injectors may rise from the initial DI _ pi to the threshold level DI _ Po. The threshold pressure DI _ Po in the high pressure fuel rail is higher than the threshold pressure PI _ Po in the low pressure fuel rail. After both fuel rails are pressurized to their respective upper threshold, all fuel pumping is suspended until the calibration event for a given port injector is complete (or disabled). For example, if the fuel pressure in the high-pressure fuel rail drops below a predetermined minimum pressure threshold, the calibration event may be disabled. The predetermined minimum pressure threshold may be the fuel pressure at which DI fuel injection is impaired. This may occur, for example, because multiple direct fuel injections occur for each port fuel injection during calibration. Thus, the calibration diagnostic may be disabled in the event that fuel in the high-pressure fuel rail falls below a predetermined minimum pressure threshold.

After each injection, the pressure in each of the fuel rails may experience a drop as shown in FIG. 10B. The pressure of each injection may be determined via the method discussed above in fig. 7. Port injector performance may be evaluated by correlating the pressure drop after each injection to a modeled or expected pressure drop. For example, at time t2, the fuel rail pressure drop (represented at line 1005 on map 1000) after injection via the port fuel injector may be calculated as the difference between P1 (the pressure before the injection event) and P2 (the pressure after the injection event).

As discussed above with respect to the method of fig. 9, in some examples, more than one PFI may be diagnosed by simply repeating the method of fig. 9 for each individual PFI/cylinder pair. Turning to fig. 11A, an exemplary plot 1100 is depicted illustrating pressure in a low pressure fuel rail (e.g., the second fuel rail 260 of fig. 2) as a function of time for each PFI of a four cylinder engine during the diagnostic method of fig. 9 (as shown in fig. 10A-10B). Graph 1105 represents a first PFI corresponding to cylinder 1, graph 1106 represents a second PFI corresponding to cylinder 2, graph 1107 represents a third PFI corresponding to cylinder 3, and graph 1108 represents a fourth PFI corresponding to cylinder 4. Graph 1110 represents a modeled or expected pressure as a function of time for each of the engine cylinders. Line 1112 represents a predetermined threshold for indicating the presence or absence of fuel system degradation.

As shown in FIG. 11A, the pressure in the low pressure fuel rail steadily decreases over time as fuel is injected into its respective cylinder via PFI alone. It will be appreciated that "time" is relative in this example, as the diagnosis of each PFI is not performed simultaneously, but rather sequentially. Further, the graph may be understood to represent a fit to the individually measured pressure drops corresponding to each individual PFI.

Each of graphs 1105, 1106, and 1107 are shown to be within a predetermined threshold (line 1112) of a modeled or expected pressure drop (graph 1110), while graph 1108 is shown to be outside of the predetermined threshold of the modeled or expected pressure drop. In this exemplary illustration, the pressure drop of the fourth PFI changes more rapidly over time (graph 1108) than the remaining PFIs that have passed the diagnostic routine of fig. 9. Thus, in this example, the controller may infer that there is degraded functional operation associated with the fourth PFI injector, while the remaining PFI injectors are inferred to function as desired or expected. More specifically, due to the fact that the fourth PFI is associated with a faster pressure drop than the remaining PFIs, the controller may infer that the fourth PFI is stuck in an at least partially open position, thereby causing the PFI to appear to open more than an expected period of time at each fuel injection. Although not explicitly shown, in another example where an abnormal PFI is determined to have a pressure drop that is slower than expected (and slower than the remaining PFIs), the controller may infer that the abnormal PFI may be in a normally closed fault, thereby causing the PFI to appear to close for more than an expected period of time on each fuel injection.

For example, where both the open time determination and the close time determination are relied upon to infer fuel pressure and the fuel injector is in a normally open fault, the open time may be expected, but the close time may be longer (due to the injector being in a normally open fault). A longer closing time can be inferred as a lower pressure, since the valve can close more slowly at lower pressures. Alternatively, in the event that the fuel injector is in a normally closed failure, the opening time may be longer (due to the valve being in a normally closed failure), which may be inferred as a greater pressure, while the closing time may be expected. In the case of a normally open fault of the fuel injector, the controller may therefore infer that the actual pressure is lower by averaging the open time measurement and the closed time measurement, whereas in the case of a normally closed fault of the fuel injector, the controller may infer that the actual pressure is higher by averaging the open time measurement and the closed time measurement.

Turning to fig. 11B, an exemplary plot 1150 is depicted that illustrates pressure in a low pressure fuel rail (e.g., the second fuel rail 260 of fig. 2) as a function of time for each PFI of a four cylinder engine during the diagnostic method of fig. 9 (as shown in fig. 10A-10B). Graph 1155 represents a first PFI corresponding to cylinder 1, graph 1156 represents a second PFI corresponding to cylinder 2, graph 1157 represents a third PFI corresponding to cylinder 3, and graph 1158 represents a fourth PFI corresponding to cylinder 4. Graph 1160 represents a modeled or expected pressure drop as a function of time for each of the individual injectors. Line 1162 represents a predetermined threshold for indicating the presence or absence of degradation.

As shown in FIG. 11B, the pressure in the low pressure fuel rail steadily decreases over time as fuel is injected into its respective cylinder via PFI alone. Similar to that discussed above, the "time" is relative in this example, as the diagnosis of each PFI is not done simultaneously, but rather sequentially. Further, the graph may be understood to represent a fit to the individually measured pressure drops corresponding to each individual PFI.

None of the graphs 1155-1158 are determined to be within the predetermined threshold (line 1162) of the modeled or expected pressure drop (graph 1160). In this example, it may not be possible for all PFIs to exhibit degradation, but rather may indicate more general fuel system degradation. In other words, the pressure relief mechanism (e.g., the pressure relief valve 242 in fig. 2) may have problems, the check valve (e.g., the check valve 244 in fig. 2) may have problems, and so forth.

The maps of fig. 10A-10B and the corresponding graphs of fig. 11A-11B relate to the method of fig. 9, wherein individual PFIs are diagnosed individually (e.g., sequentially). However, it is recognized herein that in another example, there may be an opportunity to infer whether fuel system degradation is likely to be present in a faster manner, wherein if this rapid diagnosis indicates that fuel system degradation is likely not to be present, the diagnosis of FIG. 9 may be avoided until the presence of a possible or expected fuel system degradation is inferred. Thus, turning to FIG. 12, high level exemplary method 1200 depicts an alternative method for correlating an inferred fuel pressure measurement with a modeled fuel pressure to infer the presence/absence of fuel system degradation. Similar to the method of FIG. 9, method 1200 involves evaluating port fuel injectors in a single fuel dual injector of a dual fuel rail per cylinder system. Specifically, the fuel rail pressure in both the high-pressure fuel rail (e.g., the first fuel rail 250 in fig. 2) and the low-pressure fuel rail (e.g., the second fuel rail 260 in fig. 2) may be raised to a predetermined level at which pumping may be suspended and fuel may be injected to each of the plurality of cylinders via PFI in order to detect a pressure drop in the fuel rail supplying fuel to the PFI. Although each cylinder receives fuel from port fuel injection, each cylinder may additionally receive fuel via direct injection. In this way, the diagnosis of fig. 9 can be performed as follows: the amount of time taken to conclude fuel system degradation is reduced compared to that discussed above with respect to fig. 9-11B.

The method 1200 may be performed by a controller (such as the controller 12 in fig. 1) and may be stored as executable instructions in a non-transitory memory at the controller. The instructions for performing method 1200 and the remaining methods included herein may be performed by a controller based on instructions stored on a memory of the controller in conjunction with signals received from sensors of a vehicle system, such as the sensors described above with reference to fig. 1 and 2. The controller may employ vehicle system actuators, such as a lift pump (e.g., fuel pump 212 in FIG. 2), one or more port fuel injectors (e.g., port fuel injector 170 in FIG. 1), one or more direct fuel injectors (e.g., direct fuel injector 166 in FIG. 1), a high pressure fuel pump (e.g., fuel pump 214 in FIG. 2), etc., to change the state of devices in the physical world according to the methods described below.

The method 1200 begins at 1205 and includes indicating whether a condition for relating the inferred fuel pressure to the modeled fuel pressure is satisfied. The conditions of such a correlation method may be satisfied after one or more of a predetermined number of miles traveled since the correlation method was last performed, after a predetermined duration of time has elapsed since the correlation method was last performed, in response to an indication that there may be fuel system degradation (e.g., an indication of engine lag, stall, engine surge, etc.), and so forth. If at 1205 it is indicated that the condition is not met, method 1200 proceeds to 1210 where the current operating conditions are maintained. For example, the current fuel injection schedule may be maintained without performing the diagnostic method of FIG. 12. Method 1200 may then end.

Returning to 1205, in response to indicating that the conditions for performing the diagnostic method of fig. 12 are satisfied, the method 1200 may proceed to 1215. At 1215, the method 1200 includes operating the lift pump to raise the pressure in the low pressure fuel rail to a first threshold pressure (e.g., a maximum pressure or a pressure relief point), and may also include operating the higher pressure pump to increase the pressure in the high pressure fuel rail to a second threshold pressure, in a manner similar to that discussed above with respect to steps 920 and 925 in fig. 9.

Proceeding to 1220, the method 1200 includes deactivating the lift pump and the high pressure pump in a manner similar to (e.g., simultaneously or sequentially) the manner discussed above at step 930 of fig. 9. With the pump deactivated, the method includes doing so in response to conditions being met for fuel injection to their respective engine cylinders via both the direct and port fuel injectors (e.g., based on an engine firing sequence). In other words, unlike the method of FIG. 9 (where one cylinder is selected for port fuel injection and the remaining cylinders receive direct fuel injection), the method of FIG. 12 includes maintaining both port fuel injection and direct fuel injection to each of the engine cylinders.

Proceeding to 1225, method 1200 includes inferring fuel pressure in the low pressure fuel rail via the method of FIG. 7 at each port fuel injection for each PFI. Specifically, where the firing order is 1, 4, 3, 2, it will be appreciated that pressure in the low pressure fuel rail may be inferred in response to fuel injection into cylinder 1, then in response to fuel injection into cylinder 4, then in response to fuel injection into cylinder 3, then in response to fuel injection into cylinder 2, and so on. In other words, the open time determination and/or the close time determination inferred from the power profile as discussed above at FIG. 7 may enable a low pressure rail pressure determination at each port fuel injection.

Proceeding to 1230, the method 1200 includes storing the inferred pressure results in the controller. At 1235, method 1200 includes determining whether a predetermined total number of injections have been performed. It may be desirable to ensure that each cylinder receives the same number of fuel injections, and thus in some examples, the predetermined total number of injections may be a multiple of 4 (for a four cylinder engine). For example, for a four cylinder engine, the predetermined number of injections may be 8, 12, 16, 20, etc.

If the predetermined number of injections has not been met at 1235, the method 1200 continues to inject fuel into the cylinder as discussed above. Alternatively, method 1200 proceeds to 1240 in response to a predetermined number of injections having been performed. At 1240, method 1200 includes processing the data. In some examples, processing the data may include inferring a slope corresponding to a fit of the time-varying low pressure fuel rail pressure drop data, as will be set forth in more detail in fig. 14A-14B.

At step 1245, the processed data may be compared to modeled or expected pressure changes. The details of this comparison will be discussed in more detail in fig. 14A-14B. Based on the comparison, the presence or absence of degradation may be determined. At 1255, the method 1200 may include updating the operating parameter based on determining the presence or absence of the degradation. For example, similar to that discussed above with respect to fig. 9, in response to the absence of degradation, the plan for performing the calibration method of fig. 12 may be updated. Alternatively, in response to the indication of degradation, a flag may be set in the controller and/or an MIL may be illuminated in the vehicle dashboard to notify the vehicle operator of a request to service the vehicle. In some examples indicating degradation, the controller may schedule a diagnosis to infer the source of the degradation, which may include scheduling the diagnosis discussed above with respect to fig. 9. In some examples where fuel system degradation is indicated, the controller may command the powertrain to preferentially operate in an electric mode of operation, where possible, to avoid further use of the degraded fuel system. Method 1200 may then end.

Turning now to fig. 13A-13B, fig. 13A depicts an exemplary map 1300 corresponding to the method of fig. 12, showing fuel injection timing plotted on the y-axis and cylinder number plotted on the x-axis. Similar to FIG. 10A, the depicted example is for a four cylinder engine, where each cylinder includes a direct injector and a port injector. The top graph 1302 represents the firing sequence of the direct injector, and each portion of the fuel injection via the direct injector is depicted by a dashed box. The bottom graph 1304 of FIG. 13A represents the firing sequence of the port injector, and each portion of port injected fuel is shown as a diagonally striped box. Line 1303 represents the beginning of the port calibration sequence corresponding to time t1 of map 1310 of FIG. 13B. Line 1305 represents a timing corresponding to time t2 of map 1310 of fig. 13B. Graph 1312 illustrates a change in rail pressure within a low pressure fuel rail (e.g., second rail 260 of FIG. 2) as the port injector is adding fuel to each cylinder during a calibration procedure. Graph 1314 depicts the change in fuel rail pressure within a high pressure fuel rail (e.g., first fuel rail 250 in FIG. 2) when fuel is injected to engine cylinders via direct injection during a calibration procedure.

Prior to time t1 represented by line 1303 in fig. 13A, during engine operation without the calibration process in fig. 12, fuel may be provided to each cylinder of the engine via both PFI and DI, and the fuel pressure in both fuel rails may be maintained at the initial operating pressure (e.g., via controlling operation of pulsed lift pump 212 in fig. 2). At line 1303, a port injector calibration sequence may begin for a port fuel injector based on conditions being met for performing the calibration diagnostic of FIG. 12. In contrast to the routine of FIG. 9, the routine of FIG. 12 allows each engine cylinder to receive fuel via both port and direct injections.

As shown by the map 1310 of fig. 13B, the fuel rail pressure may increase to a threshold level in each of the two fuel rails before the calibration event at time t1 begins. The pressure in the low-pressure fuel rail coupled to the port injector may increase from an initial level PI _ PI to an upper threshold level PI _ Po. Similarly, the pressure in the high-pressure fuel rail coupled to the direct injector may rise from the initial DI _ Pi to the threshold level DI _ Po. The threshold pressure DI _ Po in the high pressure fuel rail is higher than the threshold pressure PI _ Po in the low pressure fuel rail. After both fuel rails are pressurized to their respective upper threshold, all fuel pumping is suspended until the calibration event for a given port injector is complete (or disabled). For example, if the fuel pressure in the high-pressure fuel rail drops below a predetermined minimum pressure threshold, the calibration event may be disabled. The predetermined minimum pressure threshold may be the fuel pressure at which DI fuel injection is impaired.

After each injection, the pressure in each of the fuel rails may experience a drop as shown in FIG. 13B. The pressure of each injection may be determined via the method discussed above in fig. 7. Port injector performance may be evaluated by correlating the pressure drop after each injection to a modeled or expected pressure drop. For example, at time t2, the fuel rail pressure drop (represented at line 1005 on map 1000) after injection via the port fuel injector may be calculated as the difference between P1 (the pressure before the injection event) and P2 (the pressure after the injection event).

Fig. 14A-14B illustratively depict various data that may be obtained via the method of fig. 12. Specifically, fig. 14A depicts an exemplary graph 1400 that shows an example in which a change in pressure over time (as inferred via the open time determination and/or the close time determination discussed above with respect to fig. 7) of a fuel rail (e.g., low pressure fuel rail 260 in fig. 2) is indicated as being correlated with (e.g., within a predetermined threshold of) the modeled change in pressure over time. Thus, graph 1403 depicts the inferred pressure drop, and graph 1405 depicts the modeled pressure drop. The predetermined threshold is represented by line 1406. As shown, pressure is inferred at each fuel injector on/off event for each fuel injector based on an engine firing sequence (e.g., 1-4-3-2). As discussed above, a predetermined number of inferred pressure determinations may be obtained, which may enable a rapid assessment of whether there may be degradation in the fuel system. In the exemplary illustration of FIG. 14A, because the inferred pressure change over time is within the predetermined threshold of the modeled pressure change, it may be appreciated that the controller may infer that there is no fuel system degradation.

Alternatively, the exemplary illustration 1450 in fig. 14B depicts a situation where the inferred pressure changes over time are not correlated with the modeled pressure changes. Specifically, the graph 1453 depicts an inferred pressure change over time (as inferred via the open time determination and/or the close time determination discussed above with respect to fig. 7) of a fuel rail (e.g., the low pressure fuel rail 260 in fig. 2). Graph 1455 depicts modeled pressure changes over time. The predetermined threshold is represented by line 1456. In exemplary illustration 1450, because the inferred pressure change over time is not within the predetermined threshold of the modeled pressure change over time, it may be appreciated that the controller may infer that a source of fuel system degradation may be present. Degradation may originate from one or more of the fuel injectors themselves (e.g., a normally open fault or a normally closed fault), or may be related to another degradation source or type (e.g., degradation of the pressure relief mechanism, degradation of the check valve, etc.). Thus, in the case where the method of FIG. 12 is performed and the type of data returned is of a similar nature to that depicted in FIG. 14B, then the controller may schedule subsequent tests similar to those discussed above in FIG. 9 in order to better understand the particular type of fuel system degradation that may occur that results in the inferred pressure change being unrelated to the modeled pressure change.

In this way, fuel injection pressure may be determined based on operation of individual fuel injectors. In particular, information regarding the opening and closing times of individual inward opening fuel injectors may be inferred based on monitored power profiles for fuel injector activation/deactivation, and the opening time determination and/or closing time determination may be used to infer fuel injection pressure. Thus, when relying on fuel injectors to provide fuel to engine cylinders, the fuel injection pressure may be continuously updated based on the power profile of the individual fuel injectors.

A technical effect of inferring fuel injection pressure based on operation of individual fuel injectors is that, in some examples, reliance on corresponding fuel rail pressure sensors may be avoided, which may reduce cost and complexity of a vehicle fuel system. For example, a particular technical effect is that a fuel system including a port fuel injector and a low pressure fuel rail that receives fuel via a pulsed lift pump may operate without a dedicated rail pressure sensor. In other examples, a technical effect of inferring fuel injection pressure based on operation of individual fuel injectors may be that the inferred fuel injection pressure may be used to determine whether a fuel rail pressure sensor is functioning as expected or is exhibiting degraded functionality.

The systems and methods discussed herein may implement one or more systems and one or more methods. In one example, a method comprises: commanding injection of a predetermined amount of fuel into a cylinder of an engine via a fuel injector; monitoring an electrical energy profile associated with the fuel injector in response to the command; inferring a fuel injection pressure based on the electrical energy profile; and controlling a follow-up fuel injection based on the inferred fuel injection pressure. In a first example of the method, the method further comprises wherein the fuel to be injected into the cylinder of the engine is contained in a fuel rail; and wherein the fuel rail does not include a pressure sensor for measuring the fuel injection pressure. A second example of the method optionally includes the first example, and further includes wherein the fuel rail is a low pressure fuel rail; and wherein the fuel injector is a port fuel injector. A third example of the method optionally includes any one or more or each of the first to second examples, and further includes wherein the fuel rail is a high pressure fuel rail; and wherein the fuel injector is a direct fuel injector. A fourth example of the method optionally includes any one or more or each of the first through third examples, and further includes where the fuel injector is an open-in configuration fuel injector. A fifth example of the method optionally includes any one or more or each of the first through fourth examples, and further includes wherein controlling the subsequent fuel injection includes controlling a fuel injection pulse width of a next fuel injection based on a firing order of the engine. A sixth example of the method optionally includes any one or more or each of the first through fifth examples, and further includes determining a fuel injector full open time based on the electrical energy profile; and inferring the fuel injection pressure based on the fuel injector full open time. A seventh example of the method optionally includes any one or more or each of the first through sixth examples, and further includes determining a fuel injector full off time based on the electrical energy profile; and inferring the fuel injection pressure based on the fuel injector full closure time.

Another example of a method includes: commanding a fuel injector to deliver a predetermined amount of fuel contained in a fuel rail to a cylinder of the engine; determining a first duration of time from when the fuel injector is actuated open to when the fuel injector is fully open and/or determining a second duration of time from when the fuel injector is actuated closed to when the fuel injector is fully closed; and indicating the presence or absence of degradation associated with a pressure sensor that determines a measured fuel injection pressure in the fuel rail based on the first duration and/or the second duration. In a first example of the method, the method further comprises: determining an inferred fuel injection pressure based on the first duration and/or the second duration; indicating that there is no degradation of the pressure sensor when the inferred fuel injection pressure is within a predetermined threshold of the measured fuel injection pressure; and indicating a degradation of the pressure sensor when the inferred fuel injection pressure is not within the predetermined threshold of the measured fuel injection pressure. A second example of the method optionally includes the first example, and further comprising: controlling a fuel injection parameter based on the measured fuel injection pressure in response to an indication of absence of degradation associated with the pressure sensor; and controlling the fuel injection parameter based on the inferred fuel injection pressure in response to an indication of a presence of degradation associated with the pressure sensor. A third example of the method optionally includes any one or more or each of the first through second examples, and further includes wherein the first duration and the second duration are inferred based on a monitored electrical energy profile associated with the fuel injector in response to actuation of opening the fuel injector and actuation of closing the fuel injector, respectively. A fourth example of the method optionally includes any one or more or each of the first to third examples, and further includes wherein the fuel rail is a high pressure fuel rail or a low pressure fuel rail; and wherein the fuel injector is a direct fuel injector or a port fuel injector, respectively.

An example of a system for a vehicle includes: a fuel system including a pulsed lift pump that supplies fuel from a fuel tank to a low pressure fuel rail; a set of port fuel injectors supplying fuel from the low pressure fuel rail to a set of cylinders of an engine; and a controller having computer readable instructions stored on a non-transitory memory that, when executed, cause the controller to: command injection of a predetermined amount of the fuel into a cylinder of the set of cylinders via a port fuel injector of the set of port fuel injectors; determining a fuel injection pressure of the fuel in the fuel rail based on a port fuel injector full open time and/or a fuel injector full close time; and controlling a fuel injection pulse width of a subsequent fuel injection to another engine cylinder based on the fuel injection pressure. In a first example of the system, the system further comprises wherein the set of port fuel injectors are open-in fuel injectors comprising a valve mechanism having an opening rate and a closing rate that are a function of the fuel injection pressure. A second example of the system optionally includes the first example, and further includes wherein the low pressure fuel rail does not include a pressure sensor. A third example of the system optionally includes any one or more or each of the first through second examples, and further includes wherein the controller stores further instructions to continuously update the fuel injection pressure based on each fuel injector full on time and/or each fuel injector full off time when the engine is operating in a combustion mode. A fourth example of the system optionally includes any one or more or each of the first through third examples, and further includes wherein the controller stores further instructions to infer the port fuel injector full open time and/or the fuel injector full close time based on monitored electrical energy profiles corresponding to activation and/or deactivation of the fuel injector, respectively. A fifth example of the system optionally includes any one or more or each of the first through fourth examples, and further includes wherein the fuel rail includes a pressure sensor; and wherein the controller stores further instructions to indicate degradation of the pressure sensor in response to the fuel injection pressure differing from a monitored fuel injection pressure indicated by the pressure sensor by more than a predetermined threshold; and controlling the fuel injection pulse width of the follow-up fuel injection to another cylinder based on the fuel injection pressure in response to the pressure sensor being indicated as degraded. A sixth example of the system optionally includes any one or more or each of the first through fifth examples, and further includes wherein the port fuel injector full open time is independent of a voltage supplied to the port fuel injector.

In another representation, a method comprises: inferring a first pressure drop in a fuel rail at a first time corresponding to activation and deactivation of a plurality of fuel injectors supplying fuel to an engine of a vehicle, the inferred first pressure drop determined based on an opening time and/or a closing time of each of the plurality of fuel injectors; comparing the inferred first pressure drop to a first modeled pressure drop; and indicating the presence of fuel system degradation in response to the inferred first pressure drop not correlating to the first modeled pressure drop. In one example of the method, the method comprises: inferring a second pressure drop in the fuel corresponding to activation and deactivation of a single fuel injector selected from the plurality of fuel injectors; comparing the second pressure drop to a second modeled pressure drop; and indicating that the fuel system degradation corresponds to the single fuel injector in response to the second pressure drop not being correlated to the second modeled pressure drop. In other words, the method may include performing the method of fig. 12, and performing the method of fig. 9 in response to an indication of fuel system degradation in order to potentially pinpoint a source of fuel system degradation.

It should be noted that the exemplary control and estimation routines included herein may be used with various engine and/or vehicle system configurations. The control methods and programs disclosed herein may be stored as executable instructions in a non-transitory memory and executed by a control system including a controller in conjunction with various sensors, actuators, and other engine hardware. The specific routines described herein may represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. Various acts, operations, and/or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated acts, operations, and/or functions may be repeatedly performed depending on the particular strategy being used. Further, the described acts, operations, and/or functions may graphically represent code to be programmed into the non-transitory memory of a computer readable storage medium in an engine control system, wherein the described acts are implemented by execution of instructions in combination with an electronic controller in a system comprising various engine hardware components.

It will be appreciated that the configurations and routines disclosed herein are exemplary in nature, and that these specific embodiments are not to be considered in a limiting sense, because numerous variations are possible. For example, the above techniques may be applied to V-6, I-4, I-6, V-12, opposed 4, and other engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and subcombinations of the various systems and configurations, and other features, functions, and/or properties disclosed herein.

As used herein, unless otherwise specified, the term "about" should be understood to mean plus or minus five percent of the range.

The following claims particularly point out certain combinations and subcombinations regarded as novel and nonobvious. These claims may refer to "an" element or "a first" element or the equivalent thereof. Such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and/or properties may be claimed through amendment of the present claims or through presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, also are regarded as included within the subject matter of the present disclosure.