阅读说明：本技术 燃料泵、机动车辆以及操作燃料泵的方法 (Fuel pump, motor vehicle and method for operating a fuel pump ) 是由 斯特凡·雷维达 约翰内·乌尔里克 于 2020-07-29 设计创作，主要内容包括：本发明涉及燃料泵、机动车辆以及操作燃料泵的方法。提供一种用于机动车辆的液体燃料喷射系统的燃料泵。用于燃料喷射系统的燃料泵包括在低压下从机动车辆的燃料罐提供液体燃料的低压泵。高压泵与低压泵流体连通并且将液体燃料从低压压缩成高压,以将液体燃料喷射到机动车辆的内燃机中。泵驱动器以独立于机动车辆的内燃机的发动机速度的泵频率对低压泵和高压泵进行同步驱动。(The invention relates to a fuel pump, a motor vehicle and a method of operating a fuel pump. A fuel pump for a liquid fuel injection system of a motor vehicle is provided. Fuel pumps for fuel injection systems include low pressure pumps that provide liquid fuel at low pressure from a fuel tank of a motor vehicle. The high pressure pump is in fluid communication with the low pressure pump and compresses the liquid fuel from a low pressure to a high pressure for injection into an internal combustion engine of the motor vehicle. The pump drive synchronously drives the low-pressure pump and the high-pressure pump at a pump frequency that is independent of an engine speed of an internal combustion engine of the motor vehicle.)

1. A fuel pump for a liquid fuel injection system of a motor vehicle, comprising:

a low-pressure pump configured to provide low-pressure liquid fuel from a fuel tank of the motor vehicle;

a high-pressure pump in fluid communication with the low-pressure pump and configured to compress the liquid fuel from the low pressure to a high pressure to inject the liquid fuel into an internal combustion engine of the motor vehicle; and

A pump drive configured to synchronously drive the low-pressure pump and the high-pressure pump at a pump frequency that is independent of an engine speed of the internal combustion engine of the motor vehicle.

2. A fuel pump as claimed in claim 1, wherein the pump driver is configured as an electric motor.

3. A fuel pump as claimed in claim 2, wherein the pump driver comprises at least two electric sub-machines axially coupled to each other between the low pressure pump and the high pressure pump.

4. A fuel pump as claimed in claim 3, wherein each of the sub-motors comprises a helical cooling channel configured to flush the liquid fuel from a low pressure side to a high pressure side along a helical path about an axial direction of the respective sub-motor.

5. A fuel pump as claimed in claim 4, wherein each said spiral cooling channel is integrated into the housing of the respective motor sub-machine.

6. A fuel pump as claimed in claim 5, further comprising a hydraulic regulator configured to provide a pressure regulating connection between the sub-motors to deliver the liquid fuel between the sub-motors.

7. A fuel pump as claimed in claim 6, wherein the hydraulic regulator comprises an overflow return valve for pressure regulating return flow of the liquid fuel from the high pressure side to the low pressure side.

8. The fuel pump of claim 7, wherein the high-pressure pump includes a suction piston configured to compress the liquid fuel delivered to the high-pressure pump from the low-pressure pump, and a crank driver driven by the pump driver and configured to drive the suction piston.

9. A fuel pump as claimed in claim 8, wherein the pump driver is a brushless dc motor.

10. The fuel pump of claim 9, further comprising a pump controller configured to operate the fuel pump based on a pressure control command in accordance with an on-board diagnostic controller area network signal.

11. A motor vehicle comprising an internal combustion engine and a liquid fuel injection system configured to inject the liquid fuel into the internal combustion engine, the liquid fuel injection system having the fuel pump of claim 1.

12. The motor vehicle of claim 11, wherein the fuel pump is mechanically decoupled from the internal combustion engine of the motor vehicle, and wherein the fuel pump is in fluid communication with the internal combustion engine via a fuel conduit.

13. The motor vehicle of claim 12, wherein the fuel pump is powered by a vehicle battery of the motor vehicle.

14. The motor vehicle of claim 13, wherein a pump controller of the fuel pump is communicatively coupled with an engine controller of the motor vehicle.

15. A method for operating a fuel pump according to claim 1, comprising the steps of:

pumping low pressure liquid fuel from the fuel tank of the motor vehicle with the low pressure pump; and is

Compressing the liquid fuel from the low pressure to a high pressure with the high pressure pump to inject the liquid fuel into an internal combustion engine of the motor vehicle;

wherein the low-pressure pump and the high-pressure pump are driven synchronously by a pump drive at a pump frequency that is independent of an engine speed of the internal combustion engine of the motor vehicle.

Technical Field

The present disclosure relates to a fuel pump for a liquid fuel injection system of a motor vehicle, and more particularly, to a fuel pump for a gasoline direct injection system of a motor vehicle.

Background

To meet customer demand for passenger vehicles and to meet future CO₂Emissions and exhaust emissions regulatory targets, modern high efficiency gasoline internal combustion engines typically rely on Gasoline Direct Injection (GDI). The present technology enables great benefits to be achieved, in particular, for engines having a high specific electrical output and complying with new exhaust gas regulations. GDI generally offers the possibility of reducing the number of assembled parts and the overall weight.

The fuel supply architecture of modern GDI engines typically delivers gasoline from a fuel tank at low pressure of about 3 to 6bar by continuously driving a supply pump. The gasoline is then delivered to a high pressure pump configured to pressurize the gasoline to a pressure of about 50 to 500bar and pump the gasoline onto the injection rail and from there further to the fuel injectors. The gasoline pressure is regulated by an Engine Control Unit (ECU) of the vehicle via a pump.

The high pressure pump is typically mounted and fixed to a component of the respective internal combustion engine (requiring a very rigid connection due to high forces of-3500N and higher) and is mechanically driven by the crankshaft of the engine. The pump frequency and/or the pump speed of the high-pressure pump is thereby correlated to the engine speed of the internal combustion engine. Furthermore, in general, the pump system has a high energy requirement and needs to be matched to the fuel requirement of the respective engine. Due to the fixed connection of the high pressure pump, the displacement of the pump needs to match the highest injection volume per stroke of the engine. Thus, in general, the system may not achieve the highest possible efficiency and different types of vehicles may require different pump configurations, which means that a variety of different pumps may be required to meet customer needs.

In order to stabilize the pressure along the injection rail and avoid high energy consumption, modern high pressure pumps typically employ a Digital Intake Valve (DIV) that regulates the amount of pressurized fuel delivered from low pressure to high pressure at given time intervals. DIVs mainly utilize electromagnetically actuated valves and emit sound at high frequencies of about 5kHz to 10 kHz.

This produces a mechanical noise known as a "click," which can be uncomfortable to end users who enjoy a smooth driving experience (e.g., particularly due to the mounting location of the system on top of the engine assembly). To reduce these sound emissions, current solutions typically rely on significant sound insulation around the high pressure pump, potentially resulting in additional cost, weight, and performance degradation due to increased fuel heat. Furthermore, because the pump system is typically matched to engine fuel demand, the high variety of systems that may be combined may increase the cost to the manufacturer.

Disclosure of Invention

Therefore, there is a need to find a pump solution for fuel injection systems with improved efficiency and compatibility and reduced sound emission. Accordingly, the present disclosure provides a fuel pump for a gasoline direct injection system of a motor vehicle.

According to an aspect of the present disclosure, a fuel pump for a fuel injection system (specifically, a gasoline direct injection system) of a motor vehicle may include: a low pressure pump configured to provide liquid fuel at low pressure from a fuel tank of a motor vehicle; a high pressure pump in fluid communication with the low pressure pump and configured to compress liquid fuel from a low pressure to a high pressure to inject the liquid fuel into an internal combustion engine of the motor vehicle; and a pump driver configured to synchronously drive the low-pressure pump and the high-pressure pump at a pump frequency independent of an engine speed of an internal combustion engine of the motor vehicle.

According to another aspect of the present disclosure, a motor vehicle has an internal combustion engine and a liquid fuel injection system configured to inject liquid fuel into the internal combustion engine, wherein the liquid fuel injection system has a fuel pump according to the present disclosure.

According to yet another aspect of the present disclosure, a method for operating a fuel pump according to the present disclosure may include: pumping liquid fuel from a fuel tank of a motor vehicle at low pressure using a low pressure pump; and compressing the liquid fuel from a low pressure to a high pressure with a high pressure pump for injecting the liquid fuel into an internal combustion engine of the motor vehicle. The low-pressure pump and the high-pressure pump are driven synchronously by a pump drive at a pump frequency that is independent of the engine speed of the internal combustion engine of the motor vehicle.

The present disclosure decouples the pump from the internal combustion engine and instead drives the low-pressure pump and the high-pressure pump, e.g., the electric motor, with a dedicated pump driver. Accordingly, the same pump configuration may be used for a variety of different engine and vehicle types, resulting in overall cost reduction and simplification of the vehicle supply infrastructure. Furthermore, the pump system no longer needs to be mounted on top of the combustion engine and thus sound emission (in particular, the sound of a DIV) can be reduced or completely avoided. In fact, the pump system may be mounted anywhere on the vehicle, for example, in a floor or in a cofferdam within the engine compartment spaced from the actual engine. Also, DIV of the pump system can be eliminated completely. By using one common drive of both pump systems, the power consumption can be significantly reduced by optimized operating conditions.

According to the present disclosure, the pump driver may be configured to drive the pump at a pump frequency that is independent of an engine speed of an internal combustion engine of the motor vehicle. Due to the presence of a dedicated pump drive, there is no longer a need to mechanically drive the pump via the crankshaft of the engine. Thus, the pump frequency no longer needs to be coupled with the engine speed. Accordingly, the pump configuration and behavior can be adjusted in an optimized manner for each type of vehicle, type of engine, and driving situation of one single type of pump. Thus, the resulting system may be optimized to provide the highest possible efficiency or other characteristics, such as starting capability and independent rail pressure for each case, in situations where compromises must be made due to interconnection with the engine.

Furthermore, the present disclosure may be particularly applicable to GDI systems. However, the present disclosure is also applicable to other fuel injection systems based on liquid and/or liquefied fuels, including but not limited to Liquefied Natural Gas (LNG), Compressed Natural Gas (CNG), Liquefied Petroleum Gas (LPG), hydrogen, and the like.

According to an exemplary embodiment of the present disclosure, the pump driver may be an electric motor. However, it should be understood that the pump drive may be another power source that is driven independently of the engine speed of the internal combustion engine. For example, the pump drive may be a pneumatic motor, a hydraulic motor, or the like.

According to an exemplary embodiment of the present disclosure, the pump driver may comprise at least two electric sub-machines axially coupled to each other between the low pressure pump and the high pressure pump. For example, two brushless Direct Current (DC) motors may be used to generate sufficient power output (e.g., above 500W) and an additional starting function to manage high engine gradients, e.g., to ramp up the power output from 500W to 1000W on a very short time scale. Thus, flexibility in high pressure and/or flow gradients may be achieved. Also, stable injection rail pressure may be ensured throughout the dynamic range of the engine/vehicle. In other exemplary embodiments, even three, four, or more electric sub-machines may be coupled to each other to further increase the flexibility of the system.

According to an exemplary embodiment of the present disclosure, each of the motor sub-machines may include a spiral-shaped cooling channel configured to flush the liquid fuel from the low pressure side to the high pressure side along a spiral-shaped path around an axial direction of the respective motor sub-machine. Accordingly, the pump driver can be cooled down using the liquid fuel itself, which inevitably generates some heat. Since the electric motor is installed between the low-pressure pump and the high-pressure pump, fuel can be used for this purpose for traveling between the low-pressure side and the high-pressure side. For example, the fuel can be guided through the housing of the electric motor.

It will be apparent to those skilled in the art that a similar cooling mechanism may also be employed when the pump drive is not split into two or more sub-machines. In this case, it is still possible to install a pump drive between the low-pressure pump and the high-pressure pump and the pump drive can carry one or several spiral-shaped cooling channels along, for example, the outer side or the casing from the low-pressure side to the high-pressure side.

According to an exemplary embodiment of the present disclosure, each spiral cooling channel may be integrated into the housing of a respective motor sub-machine. Accordingly, a cooling flow along the entire outer side or surface of the motor sub-machine can be achieved to optimize the cooling of the pump drive. The fuel pump may further include a hydraulic regulator configured to provide a pressure regulated connection between the motor sub-machines to deliver liquid fuel between the motor sub-machines. The hydraulic regulator may be configured to regulate an internal flow of fuel and maintain an internal pressure of the flow of fuel. The internal pressure regulation system may facilitate proper filling of the fuel pump with fuel and cooling of the pump drive.

The hydraulic regulator may include an overflow return valve for pressure regulating a return flow of liquid fuel from the high pressure side to the low pressure side. Because the low pressure pump typically requires 10% -20% higher displacement than the high pressure pump, any excess fuel can be flushed back to the low pressure side. Thereby, the hydraulic regulator may provide a regulated conduit in addition to the main supply conduit. This may become necessary in certain applications for three reasons. First, the fuel pump may need to maintain a certain relative pressure. Second, the first soak may require recirculation to empty the system. Third, any fuel remaining after engine shut-down may be heated to increase internal pressure and steam content. The increased pressure can be released through the valve.

The adjustment may provide additional advantages over conventional systems. The pressure membrane normally used is no longer required. And further, this pressure stabilization may allow for the use of various liquefied fuels like LNG, LPG, CNG. In addition to flooding, the hydraulic regulator may also include a secondary pressure relief outlet for filling an additional intake manifold injection system. According to an example embodiment of the present disclosure, the high pressure pump may include an intake piston for compressing the liquid fuel delivered from the low pressure pump to the high pressure pump, and a crank driver driven by the pump driver and configured to drive the intake piston.

Here, in the present disclosure, a crank drive actuated by a pump drive may replace the crankshaft normally employed with an internal combustion engine. The intake piston (or plunger) may be configured in an optimized manner to provide a convenient range of lift (e.g., low mass per lift range, however, high enough to compress and deliver sufficient fuel). The solution may be to use one common shaft for the synchronized fuel flow from the fuel tank to the high pressure pump via the low pressure pump. According to an example embodiment of the present disclosure, a fuel pump may be configured to operate at a fuel flow rate of between 0kg/h and about 100kg/h in a pump frequency range of 0rpm and about 16.000 rpm.

In the case of fuel delivery in the small hub over the large frequency range, the pressure at the injection rail can be stabilized and adjusted precisely. The low pressure may be in the range between 1bar and about 10bar and/or the high pressure may be in the range between about 50bar and 500 bar. For example, the low pressure may be between about 3bar and 6 bar. On the other hand, the high pressure may be between about 250bar and 350bar, for example.

According to an exemplary embodiment of the present disclosure, the pump driver may be a brushless DC motor. The motor may provide sufficient power and torque as required by the present solution. The electric motor may have a maximum power output of at least 500W at an operating voltage of 48V. The fuel pump may further include a pump control unit that operates the fuel pump based on a pressure control command of an on-board diagnostic Controller Area Network (CAN) signal.

For example, the pump controller may include rail pressure control logic based on the actual rail pressure and a rail pressure set point. Since OBD messages CAN be used for simple control features, such as rail pressure control, the system CAN be further simplified by using on-board diagnostic CAN signals (OBD-CAN). Because these types of messages comply with international standards, fuel pumps may be provided in any vehicle, regardless of the manufacturer.

According to an exemplary embodiment of the present disclosure, the fuel pump may be mechanically decoupled from an internal combustion engine of the motor vehicle. However, the fuel pump may be in fluid communication with the internal combustion engine via a fuel conduit. For example, the fuel pump may be mounted within the floor of the vehicle and thereby spaced from the internal combustion engine. The fuel hoses, conduits, or lines may provide the necessary fluid communication with the injection rail of the engine.

According to an exemplary embodiment of the disclosure, the fuel pump may be powered by a vehicle battery of the motor vehicle. For example, a standard 12V battery may be employed. When a 48V motor is used, a DC/DC converter may be coupled between the battery and the motor. According to an example embodiment of the present disclosure, a pump controller of a fuel pump may be communicatively coupled to an engine controller of a motor vehicle. Thereby, a dedicated pump controller may be provided, which may for example receive power from a battery of the vehicle and may power a pump driver of the fuel pump. However, in other exemplary embodiments, the pump controller may be integrated into the engine controller.

The present disclosure will be described in more detail with reference to exemplary embodiments thereof as illustrated in the accompanying drawings.

Drawings

The accompanying drawings are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the disclosure and together with the detailed description serve to explain the principles of the disclosure. Other embodiments of the present disclosure and many of the intended advantages of the present disclosure will be readily appreciated as they become better understood by reference to the following detailed description. The elements of the drawings are not necessarily to scale relative to each other. In the drawings, like reference numbers indicate similar or functionally similar elements unless otherwise indicated.

FIG. 1 schematically depicts an embodiment of aspects of a fuel injection system including a high pressure pump;

FIG. 2 schematically illustrates a motor vehicle including the fuel injection system of FIG. 1;

FIG. 3 schematically depicts a fuel pump in the high pressure range of a liquid fuel injection system according to an exemplary embodiment of the present disclosure;

FIG. 4 schematically illustrates a motor vehicle including a liquid fuel injection system having the fuel pump of FIG. 3, according to an exemplary embodiment of the present disclosure;

FIG. 5 illustrates a side view of a fuel pump assembly of the fuel pump of FIG. 3, according to an exemplary embodiment of the present disclosure;

FIG. 6 illustrates a cross-sectional view of a hydraulic regulator of the fuel pump of FIG. 5, according to an exemplary embodiment of the present disclosure; and is

FIG. 7 illustrates a flow chart of a method for operating the fuel pump of FIG. 3 according to an exemplary embodiment of the present disclosure.

Although exemplary embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. In general, this application is intended to cover any adaptations or variations of the exemplary embodiments discussed herein.

Detailed Description

It should be understood that the term "vehicle" or "vehicular" or other similar terms as used herein generally includes motor vehicles, such as passenger vehicles including Sport Utility Vehicles (SUVs), buses, trucks, various commercial vehicles, watercraft including various watercraft, aircraft, and the like, and includes hybrid vehicles, electric vehicles, combustion vehicles, plug-in hybrid vehicles, hydrogen powered vehicles, and other alternative fuel vehicles (e.g., fuels derived from resources other than petroleum).

While exemplary embodiments are described as performing exemplary processes using multiple units, it should be understood that exemplary processes may also be performed by one or more modules. Further, it is to be understood that the term "controller/control unit" refers to a hardware device that includes a memory and a processor and that is specifically programmed to perform the processes described herein. The memory is configured to store the modules and the processor is specifically configured to execute the modules to perform one or more processes described further below.

Further, the control logic of the present disclosure may be embodied as a non-transitory computer readable medium having executable program instructions embodied thereon for execution by a processor, controller/control unit, or the like. Examples of computer readable media include, but are not limited to: ROM, RAM, Compact Disc (CD) -ROM, magnetic tape, floppy disk, flash drive, smart card, and optical data storage device. The computer readable recording medium CAN also be distributed over network coupled computer systems so that the computer readable medium is stored in a distributed fashion and executed, for example, by an on-board communications server (telematics server) or a Controller Area Network (CAN).

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

As used herein, unless explicitly stated or otherwise evident from the context, the term "about" should be understood to be within the normal tolerance of the art, e.g., within 2 standard deviations of the mean. "about" should be understood to be within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless the context indicates otherwise, all numbers provided herein are modified by the term "about".

Fig. 1 schematically depicts an implementation of aspects of a fuel injection system 10 ', which may be, in particular, a Gasoline Direct Injection (GDI) system 10' including a Digital Intake Valve (DIV) 32. Fig. 2 schematically shows a motor vehicle 100 comprising the fuel injection system 10' of fig. 1.

Because modern vehicles are required to meet the highest demands with respect to consumption, emissions, and performance standards, gasoline vehicles are mostly equipped with direct fuel injection systems. Gasoline direct injection means that fuel is directly injected into a combustion chamber (not shown) of the engine 101 through an injector and then mixing of internal gas is achieved. The system 10 'includes a low pressure (feed) fuel pump (also not shown here) that pumps gasoline from a fuel tank 104 of the vehicle 100 through a fuel conduit 106 at low pressure (e.g., -3 bar) and pumps the fuel to a low pressure fuel chamber 15 of the GDI system 10' via a low pressure fuel inlet 18. The digital inlet valve 32 shown in fig. 1 now regulates the transfer of gasoline from the low-pressure fuel chamber 15 to the high-pressure fuel chamber 16 of the high-pressure fuel pump 3', where it is injected into the injection rail 102 via the high-pressure fuel outlet 19 and into the combustion chamber of the engine 101.

The high-pressure pump 3' is configured to compress the required fuel quantity for injection to a required pressure level, for example 50bar up to about 500 bar. Correspondingly, the high-pressure pump 3' is driven by means of a plunger and/or suction piston 11 elastically connected to a tappet 34 via a return spring 20, the tappet 34 in turn being connected to a crankshaft 27 of the engine 101. Thereby, the pump frequency of the high-pressure pump 3' is driven by the speed of the internal combustion engine 101 (refer to the arrow at the intake piston 11 in fig. 1, indicating the oscillating movement of the intake piston 11). Thus, the DIV 32 must be actuated at a specified time to deliver a sufficient amount of fuel within a given time window. The DIV 32 is operated by an Engine Control Unit (ECU)103 of the engine 101 based on various sensor data. The ECU 103 is in turn driven by a vehicle battery 105 of the vehicle 100.

DIV 32 is housed within DIV housing 33 and includes three separate functional components: a valve seat 28, a valve piston 29, and a valve actuator 30 (refer to the left side of fig. 1). Valve seat 28 is configured to seal high pressure fuel chamber 16 of GDI system 10 'against low pressure fuel chamber 15 of GDI system 10' in the closed configuration of DIV 32. Valve piston 29 is configured to move valve seat 28 between the closed configuration and the open configuration of DIV 32, wherein high pressure fuel chamber 16 is in fluid communication with low pressure fuel chamber 15. The valve actuator 30 is configured as an electromagnetic linear actuator to cause the valve piston 29 to move in the actuation direction a.

The three functional parts, i.e. the valve seat 28, the valve piston 29 and the valve actuator 30, are connected together in one single integrated part, for example made of steel or the like. For example, the functional components may be welded together. DIV 32 is provided as a fully integrated, single structural component to reduce manufacturing costs and simplify the supply chain. The GDI system 10 '(i.e., specifically, the DIV 32 and the high-pressure pump 3') is mounted to the engine 101 by a rigid connection (e.g., via brackets or the like) that is required due to the high forces of several thousand newtons acting on the components during operation.

Generally, all vibrating surfaces transmit their motion into the air, which in turn generates an out-of-sphere spread wave. These waves have almost the same frequency as the vibrating body. The generated sound or acoustic noise is also referred to as solid borne sound. In a simplified condition, the solid borne sound corresponds to the resonance frequency of the whole body, including its physical boundaries of mass, stiffness, and damping.

Noise emissions from vehicles remain one of the key challenges to achieving end user satisfaction. In the case of "sporty" sounds, the drive train acoustics are influenced by positive correlation (positive perception), and in the case of harsh sounds, the drive train acoustics are influenced by negative perception (negative perception). Studies have shown that common GDI systems are a major source of mechanical noise emissions. In particular, under idle conditions, such a situation may be annoying to drivers and pedestrians. The high pressure pumps in modern gasoline direct injection engines may be audibly objectionable due to the "clicking" noise emitted by the very smooth operation of these engines. This click sound is mainly due to the rapid closing and opening movement of the digital inlet valve 32, which is regulated to the fuel inlet of the high-pressure pump 3'. This noise is enhanced by the fact that the GDI system 10' is mounted on top of the engine 101. Thereby, the entire vehicle 100 emits solid-borne sound via the engine 101.

Studies have shown that GDI system noise covers a range from 1.6kHz up to 16 kHz. In short, this range can be divided into two main areas to achieve the pump function. The pressure generation affects the region of approximately 1.6kHz to 5kHz, while the digital inlet valve affects the region of 5kHz to 10 kHz. The last mentioned range represents the noise of the above "click".

Also, the high-pressure pump 3' is driven by the crankshaft 27 of the engine 101, and thus the pump frequency (e.g., pump speed) follows the engine speed of the engine 101. This arrangement may not be optimal in terms of pump and injection efficiency, as the displacement of 3' must match the highest injection volume per stroke of the engine 101. Since the layout of the high pressure pump 3 'must handle the maximum fuel delivery rate over the entire engine duty cycle, the pump 3' is typically operated in a local load region. However, one of ordinary skill in the art will recognize that the parts operating or operating in partial load operation do not meet the highest energy efficiency levels. Furthermore, because each part has a specific efficiency map, fixed operating conditions do not yield the highest operating efficiency. Thereby, the power consumption of the parts increases.

The above-described disadvantages are overcome by the liquid fuel injection system 10 discussed with reference to fig. 3-7. Fig. 3 and 5 schematically depict a fuel pump 1 of a fuel injection system 10 according to an exemplary embodiment of the present disclosure. Fig. 5 shows in detail a side view of the components of the fuel pump 1, wherein the fuel pump 1 is shown without a housing or casing. Fig. 4 shows a motor vehicle 100 comprising a fuel injection system 10 with the fuel pump 1 in fig. 3 and 5. Fig. 7 shows a flow chart of a method M for operating the fuel pump 1 in fig. 3 and 5.

The system 10 may be configured as a GDI system for pumping gasoline from a fuel tank 104 of the vehicle 100 and injecting the gasoline into the engine 101 via the injection rail 102. However, in other exemplary embodiments, the system 10 may inject other forms of liquid fuel, such as liquefied fuel like LNG, LPG, CNG, and the like. Accordingly, the system 10 may include a low pressure pump 2 configured to provide liquid fuel at low pressure (e.g., about 3 to 6bar) from the fuel tank 105. System 10 may further include a high-pressure pump 3, high-pressure pump 3 being in fluid communication with low-pressure pump 2 and configured to compress liquid fuel from a low pressure to a high pressure, e.g., about 250 to 350bar, to inject the liquid fuel into internal combustion engine 101 of motor vehicle 100.

Accordingly, the low pressure pump 2 may be implemented in various forms, such as a gear pump (low fuel quantity), an impeller or gerotor pump (e.g., racing car applications), a side channel pump (to soak liquid fuel and a portion of liquid fuel), and the like. However, other application pumps and methods of operation are possible. On the other hand, as a simple 2-poppet solution comprising a poppet 17 on the low pressure side L and a poppet 17 on the high pressure side H, to provide the high pressure pump 3.

In contrast to the system 10' of fig. 1 and 2, the system 10 of fig. 3 to 7 may further comprise a pump driver 4 configured to drive the low pressure pump 2 and the high pressure pump 3 synchronously. The pump driver 4 may be configured to drive a crank driver 12 of the high-pressure pump 3, the crank driver 12 being connected to a tappet 34, which in turn drives a suction piston 11 of the high-pressure pump 3 configured to compress liquid fuel. The crank drive 12 with the return spring 20 is shown in fig. 5. However, it should be understood that without the spring 20, the crank drive may be configured as a rigid assembly between the piston 11 and the tappet 34. In some applications, a spring may help stabilize the system. The suction piston 11 may be configured with a suitable lift range, for example, about 2mm to 5mm, depending on the particular use. The lift range should be suitable for low mass per lift, but high enough to compress and deliver sufficient fuel.

Thus, in the exemplary embodiment of fig. 3-7, high-pressure pump 3 is not coupled to the crankshaft of engine 101. Instead of the high-pressure pump 3, it is completely decoupled from the engine 101 and is driven only by the pump drive 4 provided for this specific purpose. In fact, the entire fuel pump 1 may be mechanically separated and spaced apart from the internal combustion engine 101 (refer to fig. 4). For example, the pump 1 may be mounted within the floor of the vehicle 100 or within a separate compartment of an engine cabinet.

Thus, the pump driver 4 may be configured to drive the pumps 2, 3 at a pump frequency that is independent of the engine speed of the internal combustion engine 101 of the motor vehicle 100. Thus, the solution of the present exemplary embodiment is different from the commonly followed solution of fixedly connecting the GDI system to the engine mechanism. This overcomes the drawbacks of the system 10' of fig. 1 and 2, as set forth further below.

The method M for operating the fuel pump 1 may include: accordingly, at M1, liquid fuel is pumped from the fuel tank 105 of the motor vehicle 100 at low pressure using the low-pressure pump 2, and at M2, the liquid fuel is compressed from low pressure to high pressure using the high-pressure pump 3 to inject the liquid fuel into the internal combustion engine 101 of the motor vehicle 100 (refer to fig. 7). In particular, the low-pressure pump 2 and the high-pressure pump 3 can be driven synchronously by the pump drive 4 at a pump frequency that is independent of the engine speed of the internal combustion engine 101 of the motor vehicle 100.

Referring now to fig. 5 and 6, the pump driver 4 is configured as an electric motor and may comprise two electric sub-machines 5 axially coupled to each other via an electric and mechanical connection 22 between the low-pressure pump 2 and the high-pressure pump 3. Each motor sub-machine 5 may comprise a helical cooling channel 6 integrated into its respective housing 7, configured to flush the liquid fuel from the low pressure side L (i.e. from the low pressure pump 2) to the high pressure side H (i.e. to the high pressure pump 3) along a helical path around the axial direction D of the respective motor sub-machine 5.

The two electric submarines 5 may be in fluid communication with each other via a hydraulic regulator 8, the hydraulic regulator 8 providing a pressure-regulated connection between the electric submarines 5 for conveying liquid fuel between the electric submarines 5, i.e. between the spiral-shaped cooling channels 6 of the two submarines 5.

The hydraulic modulator 8 is shown in more detail in fig. 6. As shown, the hydraulic regulator 8 may include a main regulator supply conduit 23 for delivering liquid fuel from the spiral cooling channel 6 of the motor sub-set 5 on the low pressure side L to the motor sub-set 5 on the high pressure side H, i.e., from the left to the right in fig. 5. Accordingly, the hydraulic regulator 8 may include a regulator inlet 24 in fluid communication with the main regulator supply conduit 23 on one side and a regulator outlet 25 in fluid communication with the respective cooling passage 6 on the other side. For example, the regulator inlet 24 and the regulator outlet 25 may be configured as simple ball valves or the like.

Further, the hydraulic modulator 8 may include an overflow return valve 9 (left side in fig. 6) for pressure-regulating a return flow of the liquid fuel from the high pressure side H to the low pressure side L, and a decompression outlet 26 (right side in fig. 6) for filling a parallel intake manifold injection system of the vehicle 100 (not shown). The latter offers the possibility to combine the manifold with direct injection into one pump system. Fuel pump 1 may be configured to operate at a fuel flow rate of between 0kg/h and about 100kg/h, within a pump frequency range of between 0rpm and about 16.000rpm, to enable delivery of liquid fuel to injection rail 102 in small amounts, but at higher pump speeds. This provides the possibility of controlling the injection process more accurately. Due to this, fast transitions between different driving situations can be handled in an efficient manner.

The pump driver 4 may be configured as a brushless DC motor or similar to each motor sub-machine 5 capable of delivering up to about 500W, for example, at an operating voltage of 48V (48V may be more suitable than 12V since the latter may encounter higher currents). The vehicle battery 105 can deliver the necessary electrical energy to the pump driver 4 via a dedicated electrical line 107. A DC-DC converter (not shown) may be configured to convert 12V of the vehicle battery 105 to 48V required by the pump driver 4.

As shown in fig. 4, for clarity, the fuel pump 1 may include a pump control unit 14 or pump controller that is spaced apart from the fuel pump 1. However, it should be understood that the pump controller 14 may be integrated into the fuel pump 1. In the present specific example embodiment, the pump controller 14 is provided in addition to the ECU 103. However, in other exemplary embodiments, the control functions of the pump controller 14 may be performed by the ECU 103. The independent pump controller 14 enables retrofitting the present system 10 into a vehicle equipped with a conventional system.

The fuel pump 1 may be configured to receive power from the pump controller 14, which pump controller 14 is in turn powered by the vehicle battery 105. The pump controller 14 may include, for example, rail pressure control logic based on actual values and predefined set points. Specifically, for further simplification, the pump controller 14 may be configured to operate the fuel pump 1 based on a pressure control command according to an on-board diagnostic CAN signal. These signals conform to international standards and thus the system 10 can be used between different manufacturers without modification.

Thus, the present disclosure is able to significantly reduce the noise of the ticks of the common digital intake valve by decoupling the fuel injection system 10 and, in particular, decoupling the fuel pump 1 from the engine 100. The digital intake valve may be omitted entirely. Since the fuel pump 1 can be driven by a dedicated pump driver 4, the pump 1 can be configured relatively freely (compared to conventional systems), and thus one single pump type can meet the requirements of various different types of vehicles for different driving situations and engine conditions. This also means that the power consumption of the fuel system can be reduced.

Therefore, the number of parts and the total cost can be reduced, and the entire supply infrastructure can be simplified. To achieve this, the present disclosure follows a completely new pump solution based on the synchronous driving of the low-pressure and high-pressure pumps and a "one-shaft" arrangement of the pumps 2, 3, and the electric machine 5 (refer to fig. 5, which shows the arrangement of these components along one common shaft). The present system can be arranged as a retrofit and back-up solution without requiring access to the ECU at the developer level.

In the foregoing detailed description, various features are grouped together in one or more embodiments or embodiments for the purpose of streamlining the disclosure. It is to be understood that the above description is intended to be illustrative, and not restrictive. It is intended to cover all alternatives, modifications, and equivalents of the various features and exemplary embodiments. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The exemplary embodiments were chosen and described in order to explain the principles of the disclosure and its practical application, to thereby enable others skilled in the art to utilize the disclosure and various exemplary embodiments with various modifications as are suited to the particular use contemplated.

REFERENCE LIST

1 Fuel pump

2 low pressure pump

3, 3' high pressure pump

4 pump driver

5 electric sub-machine

6 spiral cooling channel

7 outer cover

8 hydraulic regulator

9 overflow return valve

10, 10' liquid fuel injection system

11 suction piston

12 crank drive

13 crankshaft

14 pump control unit

15 low pressure fuel chamber

16 high pressure fuel chamber

17 poppet valve

18 low pressure fuel inlet

19 high pressure fuel outlet

20 return spring

21 Pump housing

22 electromechanical connector

23 main regulator supply line

24 regulator inlet

25 regulator outlet

26 reduced pressure outlet

27 engine crankshaft

28 valve seat

29 valve piston

30-valve actuator

31 magnetic coil

32 digital air intake valve (DIV)

33 DIV outer casing

34 tappet

100 motor vehicle

101 internal combustion engine

102 injection rail

103 Engine Control Unit (ECU)

104 fuel tank

105 vehicle battery

106 fuel conduit

107 electric wire

L low pressure side

H high pressure side

D axial direction

A direction of actuation

M method

Method steps M1, M2.