阅读说明：本技术 用于加快发动机升温的系统和方法 (System and method for accelerating engine warm-up ) 是由 贾森·马茨 埃里克·马修·库尔茨 大卫·汉纳 丹尼尔·约瑟夫·斯泰尔 埃里克·柯蒂斯 于 2019-06-05 设计创作，主要内容包括：本公开提供了“用于加快发动机升温的系统和方法”。提供了用于在发动机冷起动时加快所述发动机和排放装置的加热的方法和系统。在一个实例中,一种方法可以包括：在发动机冷起动之前,操作e-压缩机并且打开联接在所述e-压缩机上的再循环通道的再循环阀,以使来自所述e-压缩机的出口的压缩进气通过所述再循环通道流动到所述e-压缩机的入口；以及当所述e-压缩机的所述出口处的温度达到阈值时起动所述发动机,并且在所述发动机接通的同时继续操作所述e-压缩机。由通过所述再循环通道的所述压缩进气流量产生的加热进气提高了燃烧温度和排气温度,这可以减少所述排放装置的催化剂起燃时间。(The present disclosure provides a system and method for accelerating engine warm-up. Methods and systems are provided for expediting heating of the engine and exhaust during a cold engine start. In one example, a method may include: prior to an engine cold start, operating an e-compressor and opening a recirculation valve of a recirculation passage coupled to the e-compressor to flow compressed intake air from an outlet of the e-compressor to an inlet of the e-compressor through the recirculation passage; and starting the engine when a temperature at the outlet of the e-compressor reaches a threshold and continuing to operate the e-compressor while the engine is turned on. The heated intake air produced by the compressed intake air flow through the recirculation passage increases combustion and exhaust temperatures, which may reduce catalyst light-off time of the exhaust.)

1. A method, comprising:

Prior to an engine cold start, operating an electrically driven compressor (e-compressor) to flow intake air through an intake passage, the e-compressor being adapted with a recirculation passage coupling an outlet of the e-compressor to an inlet of the e-compressor;

Opening a recirculation valve of the recirculation passage to allow intake air to flow through the recirculation passage in a direction opposite to a flow of intake air flowing through the intake passage; and

Starting the engine when a temperature at an outlet of the e-compressor reaches a threshold temperature and continuing to operate the e-compressor while the engine is turned on.

2. The method of claim 1, further comprising opening a bypass valve of a bypass passage of a Charge Air Cooler (CAC) disposed in the intake passage to allow a portion of the intake air to flow through the bypass passage.

3. The method of claim 1, wherein operating the e-compressor prior to an engine cold start comprises activating the e-compressor when a temperature of the intake manifold is below a threshold temperature, and wherein operating the e-compressor when the engine is on generates an e-compressor load that exceeds a torque demand.

4. The method of claim 1, wherein operating the e-compressor comprises powering rotation of the e-compressor with an electric machine that receives energy from an electrical system of the engine, an amount of power supplied by the electric machine being based on a desired mass air flow rate of intake air and a pressure of an intake manifold downstream of the e-compressor.

5. The method of claim 4, wherein adjusting the amount of power supplied by the motor is based on the threshold temperature at the outlet of the e-compressor.

6. The method of claim 5, further comprising: after operating the e-compressor for a period of time, flowing the recirculated heated air to the engine and initiating combustion of the intake air in the engine, thereby heating the engine.

7. The method of claim 6, further comprising directing exhaust from the engine to one or more exhaust devices, and adjusting the recirculation valve based on a temperature of the one or more exhaust devices.

8. The method of claim 6, further comprising adjusting an intake throttle in response to an amount of work transferred from the e-compressor to the intake to adjust a mass flow rate through the e-compressor to increase combustion and exhaust temperatures.

9. The method of claim 7, further comprising: operating the e-compressor and opening the bypass valve of the bypass passage of the CAC in response to a command to regenerate a particulate filter.

10. An engine of a hybrid electric vehicle, comprising:

an air intake system coupled to an exhaust system, wherein a combustion chamber is positioned between the air intake system and the exhaust system;

An intake passage of the intake system, the intake passage being located upstream of the combustion chamber, the intake passage being configured with an electrically driven compressor (e-compressor) and a Charge Air Cooler (CAC) arranged in an airflow path;

A recirculation passage coupling a region of the intake passage downstream of the e-compressor to a region of the intake passage upstream of the e-compressor;

An exhaust arrangement arranged in the exhaust system downstream of the combustion chamber; and

A controller configured with computer-readable instructions stored on a non-transitory memory, the instructions executable by the controller to:

In response to a request for the start of the engine,

Retarding combustion at the engine, operating the e-compressor, and flowing air through the recirculation passage to heat the air when a manifold boost temperature (MCT) is below a threshold temperature;

Initiating combustion in the engine when the MCT is at least equal to the threshold temperature.

11. The engine of claim 10, wherein the recirculation passage recirculates air from an outlet of the e-compressor to an inlet of the e-compressor, and recirculates air from a region of the intake passage downstream of the e-compressor and the CAC to a region of the intake passage upstream of the e-compressor and upstream of the CAC.

12. The engine of claim 10, wherein the e-compressor is located downstream of both the CAC and turbocharger compressor.

13. The engine of claim 10, wherein the e-compressor is located upstream of both the CAC and turbocharger compressor.

14. The engine of claim 10, wherein a recirculation valve disposed in the recirculation passage opens when the MCT is below the threshold temperature and closes when the MCT is at least equal to the threshold temperature.

15. the engine as set forth in claim 10 wherein a CAC bypass valve controlling flow through the CAC bypass passage opens when the MCT is below the threshold temperature.

Technical Field

The present description relates generally to methods and systems for warming a vehicle engine prior to a cold start and restart.

Background

During an initial engine start (after a period of time when the engine is shut down and engine components are allowed to cool), fuel may be combusted at a combustion chamber of the engine, thereby generating exhaust gases. Emission devices such as three-way catalytic converters in spark ignition engines and selective catalytic reduction in diesel powered engines may be disposed in the vehicle exhaust system downstream of the combustion chamber to treat exhaust emissions. After the engine is started, it may take a period of time for the exhaust to warm to a temperature at which the device catalyst is activated. After reaching the activation temperature after a period of time called light-off, the emissions device may effectively treat conditioned combustion products, such as particulate matter, Nitrogen Oxides (NO), before releasing the exhaust gas to the atmosphere_x) Carbon monoxide (CO) and hydrocarbons.

Catalytic conversion efficiency during light-off may be low, resulting in undesirable exhaust emissions during early stages of driving. Further, fuel combustion when the engine intake air temperature is low may result in marginal or incomplete combustion, poor engine performance and drivability, and vehicle noise, vibration, and harshness (NVH). Using a heating device such as an intake air heater to warm up the engine during start-up is an impractical solution due to the size and cost of the device.

Other attempts to deal with faster engine and catalyst heating include the use of electrically assisted compressors to heat the intake air. One exemplary method is shown by Uhrich et al in US 2010/0300405. Wherein the boost device is driven at least in part by the electric motor to increase intake air delivered through the fuel vapor canister to release fuel vapor stored in the canister during engine cold start conditions. The fuel vapor is combusted in the engine cylinders, thereby heating the cylinders and the emission control devices. The use of fuel vapor for combustion may also improve air-fuel mixing and reduce emissions during catalyst light-off.

However, the present inventors have recognized potential problems with such systems. For example, heating the engine combustion chamber and the emission control devices via waste heat generated during fuel vapor combustion may still be relatively slow and dependent on the amount of fuel vapor stored. For example, if the engine is operating in cool ambient conditions, lower fuel evaporation may result in a lower amount of stored fuel vapor. The amount may not be sufficient to effectively accelerate the heating of the engine and exhaust.

Disclosure of Invention

in one example, the above problem may be solved by a method comprising: prior to an engine cold start, operating an e-compressor and opening a recirculation valve of a recirculation passage coupled to the e-compressor to flow compressed intake air from an outlet of the e-compressor to an inlet of the e-compressor through the recirculation passage; and starting the engine when the temperature at the outlet of the e-compressor reaches a threshold temperature and continuing to operate the e-compressor while the engine is turned on.

In this way, engine warm-up and catalyst light-off may be accelerated by energy transfer from the electrically driven compressor (e-compressor). For example, the engine system may be adapted with a recirculation passage that couples the intake passage downstream of the e-compressor outlet to the intake passage upstream of the compressor inlet. Prior to an engine cold start, air may be recirculated through a recirculation passage to return to the e-compressor, increasing the temperature of the air (or air/combustion gas mixture) before delivery to the engine intake. Engine combustion may be retarded to allow the intake air temperature to increase to a threshold temperature, thereby helping to warm up the exhaust of the exhaust system more quickly. Heating the intake air via recirculation through the e-compressor may also be used to regenerate the diesel particulate filter.

It should be appreciated that the summary above is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. It is not meant 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. Furthermore, 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 shows a schematic diagram of a hybrid engine system including a recirculation passage around a compressor.

FIG. 2 illustrates a first embodiment of an engine system having an electric compressor upstream of a turbocharger configured to warm intake air by recirculating air through a compressor recirculation passage while regulating mass flow to the engine.

FIG. 3 shows a second embodiment of an engine system having an electric compressor upstream of a turbocharger that is configured to warm intake air by recirculating air through a compressor recirculation passage.

FIG. 4 illustrates a third embodiment of an engine system having an electric compressor downstream of a turbocharger that is configured to warm intake air by recirculating air through a compressor recirculation passage.

FIG. 5 shows a fourth embodiment of an engine system having an electric compressor downstream of a turbocharger that is configured to warm intake air by recirculating air through a compressor recirculation passage.

FIG. 6 illustrates a first exemplary routine for operating an electrically driven compressor to drive airflow through a compressor recirculation passage to heat intake air.

FIG. 7 illustrates a second exemplary routine for operating an electrically driven compressor to drive airflow through a compressor recirculation passage to heat intake air.

FIG. 8 illustrates operation of various actuators during an engine cold start and engine parameters in response to operation over time.

Detailed Description

The following description relates to systems and methods for recirculating air through an electrically driven compressor to heat an engine and emission control devices. Air in the intake passage downstream of the compressor may be recirculated to the inlet of the compressor through a compressor recirculation passage. The hybrid vehicle may be adapted with a compressor recirculation passage, as shown in the schematic diagram of the hybrid engine system in fig. 1. Different configurations of compressor recirculation passages are shown in fig. 2-5, illustrating how the compressor recirculation passages may be positioned around an electrically driven compressor or an electrically driven compressor and a Charge Air Cooler (CAC). The electrically driven compressor may be positioned upstream of the turbocharger compressor as shown in fig. 2 and 3, or downstream of the turbocharger compressor as shown in fig. 4 and 5. The electrically driven compressor may be run prior to a cold start of the engine or restarted when the engine and emission control device are at a temperature at which the efficiency of the emission control device is low (e.g., below a light-off temperature). An example of a routine for operating an electrically driven compressor to expedite engine heating and catalyst light-off is given in fig. 6-7, providing details of the controls and operations involved in heating the engine and catalyst. Different actuator adjustments responsive to engine operating parameters before and during engine cold start, and during increased torque demand during engine warm-up temperature operation are shown in FIG. 8.

Fig. 1-5 illustrate exemplary configurations with relative positioning of various components. In at least one example, if shown directly contacting each other or directly coupled, then these elements may be referred to as directly contacting or directly coupled, respectively. Similarly, at least in one example, elements shown as abutting or adjacent to each other can abut or be adjacent to each other, respectively. For example, components placed in coplanar contact with each other may be referred to as being in coplanar contact. As another example, in at least one instance, elements that are positioned apart from one another such that there is only a space therebetween without other components may be referred to as such. As another example, elements shown above/below each other, on opposite sides of each other, or to the left and right of each other may be referred to as being so with respect to each other. Further, as shown in the figures, in at least one example, the topmost element or topmost point of an element may be referred to as the "top" of the component, while the bottommost element or bottommost point of an element may be referred to as the "bottom" of the component. As used herein, top/bottom, upper/lower, above/below may be with respect to a vertical axis of the drawings and are used to describe the positioning of elements in the drawings with respect to each other. To this end, in one example, elements shown as being above other elements are positioned vertically above the other elements. By way of another example, the shapes of elements shown in the figures may be referred to as having these shapes (e.g., rounded, straight, planar, curved, rounded, chamfered, angled, etc.). Further, in at least one example, elements shown as intersecting one another may be referred to as intersecting elements or as intersecting one another. Also, in one example, an element shown within another element or shown outside of another element may be referred to as such.

Referring to FIG. 1, an exemplary boosted engine system 100 is illustrated in FIG. 1 and includes an engine 10 of a vehicle 102. The vehicle 102 may be a hybrid vehicle having multiple torque sources available to one or more wheels. Engine 10 may be controlled by electronic engine controller 12, with engine 10 including a plurality of cylinders, one of which is shown in FIG. 1. 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 controller 12.

Engine 10 includes a combustion chamber 30 and a cylinder wall 32 with a piston 36 positioned therein and connected to a crankshaft 40. The cylinder head 13 is fastened to the engine block 14. Combustion chamber 30 is shown communicating with intake manifold 44 and exhaust manifold 48 via respective intake valve 52 and exhaust valve 54. Each intake and exhaust valve may be operated by an intake cam 51 and an exhaust cam 53. In other examples, however, the engine may operate the valves via a single camshaft or pushrod. The position of the intake cam 51 may be determined by an intake cam sensor 55. The position of exhaust cam 53 may be determined by exhaust cam sensor 57. The intake poppet valve 52 may be operated by a variable valve activation/deactivation actuator 59, which actuator 59 may be a cam-actuated valve operator. Likewise, the exhaust poppet valve 54 may be operated by a variable valve activation/deactivation actuator 58, which actuator 58 may be a cam-actuated valve operator. Intake poppet valve 52 and exhaust poppet valve 54 may be deactivated and held in a closed position preventing flow into and out of cylinder 30 for one or more complete engine cycles (e.g., two engine revolutions), thereby deactivating cylinder 30. When the cylinders 30 are deactivated, the fuel flow supplied to the cylinders 30 may also be stopped.

Fuel injector 68 is shown positioned in cylinder head 13 to inject fuel directly into combustion chamber 30, which is known to those skilled in the art as direct injection. Fuel is delivered to fuel injector 68 by a fuel system including a fuel tank 26, fuel pump 21, fuel pump control valve 25, and a fuel rail (not shown). The pressure of the fuel delivered by the fuel system may be adjusted by changing a position valve that regulates flow to a fuel pump (not shown). Additionally, a metering valve may be located in or near the fuel rail for closed loop fuel control. The pump metering valve may also regulate fuel flow to the fuel pump, thereby reducing fuel pumped to the high pressure fuel pump.

The engine intake system 9 includes an intake manifold 44, a throttle 62, a Charge Air Cooler (CAC)163, a turbocharger compressor 162, and an intake plenum 42. Intake manifold 44 is shown communicating with an optional electronic throttle 62, where electronic throttle 62 adjusts a position of throttle plate 64 to control airflow from intake plenum 46. Compressor 162 draws air from intake plenum 42 to supply plenum 46. The compressor blade actuator 84 adjusts the position of the compressor blades 19. Turbine 164 is coupled to compressor 162 via shaft 161, all three components being included in turbocharger 160.

In one example, as shown in fig. 1, the turbocharger 160 may be an electric turbocharger, wherein a shaft 161 is coupled to an electric machine 165. The electric machine 165 may be a motor or a motor/generator. When increased boost is requested, for example, as indicated by the depression of the accelerator pedal at the accelerator pedal 130, the turbocharger 160 may be spun by the electric machine 165 during an initial period in which exhaust pressure is insufficient to spin the turbine 164 up to meet the boost demand. The electric machine 165 may continue to drive the turbocharger 160 in rotation until it is determined that the exhaust pressure is high enough to rotate the turbine 164 to provide boost to the engine. The motor 165 may be deactivated, thereby transferring the source of rotational work from the motor 165 to the exhaust. In this way, turbo lag may be reduced.

The compressor speed may be adjusted via adjusting the position of the turbine variable vane control actuator 78 or the compressor recirculation valve 158. In alternative examples, the wastegate 79 may replace the turbine variable vane control actuator 78, or the wastegate 79 may be used in addition to the turbine variable vane control actuator 78. The turbine variable vane control actuator 78 adjusts the position of the variable geometry turbine blades 166. When the vanes 166 are in the open position, exhaust gas may pass through the turbine 164, thereby supplying little energy to rotate the turbine 164. When the vanes 166 are in the closed position, exhaust gas may pass through the turbine 164 and exert an increasing force on the turbine 164. Alternatively, a wastegate 79 or bypass valve may allow exhaust gas to flow around the turbine 164 in order to reduce the amount of energy supplied to the turbine. Compressor recirculation valve 158 allows compressed air at outlet 15 of compressor 162 to return to inlet 17 of compressor 162 through recirculation passage 159. Alternatively or additionally, the position of compressor variable vane actuator 78 may be adjusted to vary the efficiency of compressor 162. In this manner, the efficiency of the compressor 162 may be reduced in order to affect the flow of the compressor 162 and reduce the likelihood of compressor surge. Further, by returning air to the inlet of the compressor 162, the work performed on the air may be increased, thereby increasing the temperature of the air. Air flows into the engine 10 in the direction of arrow 5.

A flywheel 97 and a ring gear 99 are coupled to crankshaft 40. A starter 96 (e.g., a low voltage (operating at less than 30 volts) motor) includes a pinion shaft 98 and a pinion gear 95. Pinion shaft 98 may selectively advance pinion 95 to engage ring gear 99 such that starter 96 may rotate crankshaft 40 during an engine cranking. The starter 96 may be mounted directly to the front of the engine or to the rear of the engine. In some examples, starter 96 may selectively supply torque to crankshaft 40 via a belt or chain. In one example, the starter 96 is in a base state when not engaged to the engine crankshaft. Engine start may be requested via a human/machine interface (e.g., key switch, button, remote radio frequency transmission device, etc.) 69 or in response to vehicle operating conditions (e.g., brake pedal position, accelerator pedal position, battery SOC, etc.). The battery 8 can supply electric power to the starter 96 and the motor 165. The controller 12 may monitor the state of charge of the battery.

Combustion is initiated in combustion chamber 30 when the fuel auto-ignites via the combustion chamber temperature reaching the auto-ignition temperature of the fuel injected into cylinder 30. The temperature in the cylinder increases as piston 36 approaches a top-dead-center compression stroke. In some examples, a Universal Exhaust Gas Oxygen (UEGO) sensor 126 may be coupled to exhaust manifold 48 upstream of exhaust device 71. In other examples, UEGO sensor 126 may be located downstream of one or more exhaust aftertreatment devices. Additionally, in some examples, UEGO sensor 126 may be provided with NO_xAnd oxygen sensing element_xThe sensor is replaced.

At lower engine temperatures, optional glow plug 66 may convert electrical energy into thermal energy to create a hot spot next to one of the fuel spray cones of the injectors in combustion chamber 30. By creating a hot spot in combustion chamber 30 next to the fuel spray, the fuel spray plume in the cylinder may be more easily ignited, thereby releasing heat that propagates throughout cylinder 30, raising the temperature in the combustion chamber, and improving combustion. Cylinder pressure may be measured via an optional pressure sensor 67, alternatively or additionally, the sensor 67 may also sense cylinder temperature.

The exhaust device 71 may include a Diesel Particulate Filter (DPF)72 for a diesel engine or a Gas Particulate Filter (GPF)72 for a gasoline engine. In other examples, the emissions device 71 may additionally or alternatively include a diesel oxidation catalyst and/or NO_XThe catalyst is cold started. A Selective Catalytic Reduction (SCR) catalyst 73 for a diesel engine or a three-way catalytic converter (TWCC)73 for a gasoline engine may be positioned downstream of DPF/GPF 72. In another example, DPF/GPF 72 may be positioned downstream of SCR/TWCC 73. The temperature sensor 70 provides an indication of the SCR/TWCC temperature. The exhaust gas flows in the direction of arrow 7.

EGR may be provided to the engine via a high pressure Exhaust Gas Recirculation (EGR) system 83. The high-pressure EGR system 83 includes a valve 80, an EGR passage 81, and an EGR cooler 85. EGR valve 80 is a valve that blocks or allows exhaust gas to flow from upstream of exhaust 71 to a location in the engine intake system downstream of compressor 162. The EGR may be cooled via passage through EGR cooler 85. EGR may also be provided via a low pressure EGR system 75. The low-pressure EGR system 75 includes an EGR passage 77 and an EGR valve 76. Low pressure EGR may flow from exhaust 71 between DPF/GPF 72 and SCR/TWCC 73 to a location upstream of compressor 162. The low-pressure EGR system 75 may include an EGR cooler 74.

The controller 12 is shown in fig. 1 as a common microcomputer including: a microprocessor unit 102, input/output ports 104, read only memory (e.g., non-transitory memory) 106, random access memory 108, keep alive memory 110, and a common data bus. Controller 12 is shown receiving various signals from sensors coupled to engine 10, in addition to those signals previously discussed, including: engine Coolant Temperature (ECT) from temperature sensor 112 coupled to cooling sleeve 114; a position sensor 134 coupled to the accelerator pedal 130 for sensing an accelerator position adjusted by the person's foot 132; a measurement of engine manifold pressure (MAP) from a pressure sensor 121 coupled to intake manifold 44 (alternatively or additionally, sensor 121 may sense intake manifold temperature); boost pressure from pressure sensor 122; exhaust oxygen concentration from oxygen sensor 126; an engine position sensor from Hall effect sensor 118 that senses a position of crankshaft 40; measurements of air mass entering the engine from sensor 120 (e.g., a hot wire air flow meter); a measurement of throttle position from sensor 58; and SCR/TWCC temperature measurements from sensor 70. Air pressure may also be sensed (sensor not shown) for processing by controller 12.

During operation, each cylinder within engine 10 typically undergoes a four-stroke cycle: the cycle includes an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. During the intake stroke, generally, exhaust valve 54 closes and intake valve 52 opens. Air is introduced into combustion chamber 30 via intake manifold 44 and piston 36 moves to the bottom of the cylinder to increase the volume within combustion chamber 30. The position at which piston 36 is near the bottom of the cylinder and at the end of its stroke (e.g., when combustion chamber 30 is at its largest volume) is typically referred to by those of skill in the art as Bottom Dead Center (BDC). During the compression stroke, intake valve 52 and exhaust valve 54 are closed. Piston 36 moves toward the cylinder head to compress air within combustion chamber 30. The point at which piston 36 is at the end of its stroke and closest to the cylinder head (e.g., when combustion chamber 30 is at its smallest volume) is commonly referred to by those skilled in the art as Top Dead Center (TDC). In a process hereinafter referred to as injection, fuel is introduced into the combustion chamber. In some examples, fuel may be injected into a cylinder multiple times during a single cylinder cycle.

In a process hereinafter referred to as ignition, the injected fuel is ignited by compression ignition, thereby causing combustion. During the expansion stroke, the expanding gases push piston 36 back to BDC. Crankshaft 40 converts piston movement into rotational torque of the rotary shaft. Finally, during the exhaust stroke, the exhaust valve 54 opens to release the combusted air-fuel mixture to exhaust manifold 48 and the piston returns to TDC. It should be noted that the above is described by way of example only, and that intake and exhaust valve opening and/or closing timings may vary, such as to provide positive or negative valve overlap, late intake valve closing, or various other examples. Further, in some examples, a two-stroke cycle may be used instead of a four-stroke cycle.

Engine 10 may be included in a hybrid vehicle in a variety of configurations shown in FIGS. 2-5. Various engine configurations may include all or only a portion of the components shown in FIG. 1. Furthermore, some of the configurations may include additional components not shown in fig. 1. The numerical labels of engine 10 and its associated components are maintained in fig. 2-5. Furthermore, the components shown in fig. 1 and included in fig. 2-5 operate as described with respect to fig. 1 and are labeled with the same numerical labels. Therefore, the description of these elements will not be repeated for the sake of brevity. In addition, once new components are introduced and described in fig. 2-5, their description will not be repeated for the sake of brevity.

The engine 10 of FIG. 1 includes a single boosting device, such as a turbocharger 160, which may be exhaust driven or electrically driven. However, in other examples of engines, the turbocharger may be assisted by an additional compressor that may be rotated by the electric machine. In such a configuration, as shown in fig. 2-5, the electric compressor may be positioned upstream or downstream of the turbocharger compressor, and upstream or downstream of the CAC. The electric compressor may operate as an additional boost device to supplement the compression of the intake air provided by the turbocharger and reduce the likelihood of turbo lag.

In addition to the turbocharger compressor shown in FIG. 2 having four individual cylinders 30 numbered 1-4, the example 200 of the engine 10 is also adapted with an electric compressor. In this example, the engine 10 includes an electrically driven compressor (hereinafter referred to as an e-compressor) 202 that may be rotated via an electric machine 265. E-compressor 202 is positioned upstream of turbocharger compressor 262 and downstream of the region where EGR passage 77 of LP-EGR system 75 merges with intake plenum 42. The e-compressor 202 may be selectively enabled and disabled via a controller (e.g., controller 12 of FIG. 1). Additionally, the rotational speed of the motor 265 and the e-compressor 202 may be controlled and adjusted by the controller to control the boost pressure. Instead, the turbocharger compressor 262 is driven via the exhaust turbine 264 rather than via the electric machine 265. Air flows into engine 10 in the direction of arrow 204, and exhaust gases flow out of engine 10 in the direction of arrow 206.

The intake plenum 42 may include a recirculation passage 208 that allows air to flow around the e-compressor 202 from downstream of the e-compressor 202 to upstream of the e-compressor 202 in a direction opposite to the flow through the intake plenum 42. Flow through recirculation passage 208 may be controlled by recirculation valve 210. In one example, recirculation valve 210 may be a variable flow valve configured to return excess airflow to the inlet of e-compressor 202, thereby reducing the likelihood of compressor surge and allowing e-compressor 202 to operate at mass airflow rates in excess of the engine demand speed. The recirculation valve 210 may be adjustable between a fully open position and a fully closed position, or may be configured to be continuously adjustable to any position between the fully open position and the fully closed position. Thus, when recirculation valve 210 is at least partially open (e.g., not closed), a portion of the intake air flowing through intake plenum 42 may be directed through recirculation passage 208 at an inlet of recirculation passage 208 downstream of e-compressor 202 in plenum 46 to return to intake plenum 42 through an outlet of recirculation passage 208 upstream of e-compressor 202. The air that has been compressed by the e-compressor 202 may be warmed due to the additional boost provided by the e-compressor 202. The degree of air warming may be controlled by several parameters, including how long to maintain recirculation valve 210 in the at least partially open position.

For example, prior to a cold start of the engine at low ambient temperatures (such as during winter), the recirculation valve 210 may be fully opened and held open for a period of time that allows a portion of the intake air to recirculate through the e-compressor 202 three to five times (e.g., 3-5 passes through the e-compressor 202). Under warmer ambient conditions, recirculation valve 210 may be opened for a shorter period of time to pass intake air through e-compressor 202 two to three times. Once the temperature of the intake air is determined (e.g., by an air temperature sensor at the outlet of the e-compressor 202 or by a manifold boost temperature (MCT) sensor) to increase to a target temperature, the engine 10 may be turned on. The closing of recirculation valve 210 may be initiated when a target temperature is detected or when the engine is started. As another example, the magnitude of the fraction of intake air warmed by recirculation may be adjusted by increasing or decreasing the opening of recirculation valve 210.

Additionally, the amount of work performed by the e-compressor 202, such as power input from the electric motor 265, may be selected by adjusting the mass flow rate and the desired compressor outlet temperature based on the pressure ratio across the e-compressor 202. Alternatively, if the power input is held constant, the desired compressor outlet temperature and pressure may be obtained by adjusting the mass flow rate into the e-compressor 202. The details of this adjustment will be described further below.

The engine 10 of FIG. 2 may also include a mass flow sensor 220 located immediately downstream of the e-compressor 202. The mass flow sensor 220 may measure the intake air flow rate at the outlet of the e-compressor 202 as the e-compressor 202 is spun by the motor 265. The measured flow rate may be used to estimate a period of time that recirculation valve 210 remains open such that the intake air is recirculated through the e-compressor to achieve a desired temperature. The opening of the recirculation valve may be adjusted based on the measured flow rate. For example, if a certain amount of time is allowed for heating the intake air before the engine fires, the recirculation valve may be adjusted farther open if it is determined that the mass flow rate is too low to increase the intake air temperature for a given period of time. The flow rate may also be used to estimate the pressure at the e-compressor outlet, from which the pressure upstream of the CAC 265 may be inferred.

The warmed intake air recirculated through e-compressor 202 may raise the temperature of cylinders 30 as it is delivered to intake manifold 44 and combusted. The engine load may increase due to combustion of the heated intake air, hereinafter referred to as load shifting, which may increase the exhaust gas temperature and mass flow rate through exhaust manifold 48. Higher exhaust temperatures and mass flow rates may transfer heat to the exhaust 71, thereby causing faster catalyst light-off. In one example, excess air accumulated in the intake system due to operation of the e-compressor 202 may also be used to control regeneration of the DPF (or lean GPF) while the DPF/GPF is active.

Vehicle accelerator pedal release from higher load to idle or low load may occur during regeneration of the DPF/GPF. The rapid drop to low load causes the turbocharger to slow down and thus the turbocharger may not deliver enough air to the engine and exhaust system to maintain the target particulate filter temperature, possibly resulting in a filter over temperature event, which may degrade the particulate filter. To alleviate this problem, additional air may be supplied through the e-compressor 202 to maintain the temperature gradient between the walls of the DPF/GPF and the gas flowing through the exhaust 71 through heat transfer from the walls to the gas. The possibility of the temperature of the DPF/GPF walls rising to the point of degrading the DPF/GPF is reduced. As another example, the e-compressor 202 may also be used to provide additional airflow over that supplied by the turbocharger to allow additional fuel to be injected during active DPF/GPF regeneration to adjust the inlet temperature of the DPF-GPF to mitigate excessive filter loading.

The heated charge and recirculated intake air passes through the CAC 263 before being delivered to the intake manifold 44. The cooling effect of the CAC 263 on the intake air may undesirably offset the temperature increase obtained by recirculation. By configuring engine 10 with CAC bypass 212, at least a portion of the airflow may be diverted around CAC 263, thereby reducing the amount of cooling that CAC 263 applies to the air.

The engine 10 in fig. 2 may include a CAC bypass 212 to provide a path for airflow around the CAC 263. Flow through CAC bypass 212 may be controlled by a bypass valve 214 disposed in CAC bypass 212, which bypass valve 214 may either open CAC bypass 212 or block CAC bypass 212 depending on the position of bypass valve 214. In one example, bypass valve 214 may be adjustable between a fully open position and a closed position, while in other examples bypass valve 214 may be continuously adjustable to any position between the fully open position and the fully closed position. When bypass valve 214 is closed, intake air flowing through intake plenum 42 toward intake manifold 44 passes through CAC 263 and is cooled. However, when bypass valve 214 is open, at least a portion of the intake air is diverted through CAC bypass 212 and is not cooled before reaching intake manifold 44.

When the recirculation valve 210 of recirculation passage 208 is commanded open, the controller may coordinate the opening of bypass valve 214 of CAC bypass 212. This reduces the cooling effect of CAC 263 on air that has been recirculated through e-compressor 202, has been warmed up, and flows through turbocharger 262 (or from the compressor of the electric turbocharger to CAC 263 if engine 10 is configured with an electric turbocharger instead of an e-compressor). Bypass valve 214 may be configured to open when recirculation valve 210 is open and close when a target temperature of cylinder 30 and exhaust 71 is reached.

in another embodiment 300 of engine 10 shown in FIG. 3, a recirculation passage 302 having a recirculation valve 304 may return air from plenum 46 to a region upstream of e-compressor 202 from a region downstream of an outlet of bypass passage 212 and upstream of throttle 62. An e-booster bypass 303 configured with an e-compressor bypass valve 305 may branch from recirculation passage 302, coupling a region of recirculation passage 302 upstream of recirculation valve 304 to plenum 46 downstream of e-compressor 202 and upstream of turbocharger compressor 262. When the e-compressor 202 is deactivated and the recirculation valve 304 is closed, the e-compressor bypass 303 may provide a path for airflow around the e-compressor 202. The positioning of the e-compressor 202 within the intake plenum 42 may restrict flow when the e-compressor 202 is inactive. By opening the e-compressor bypass valve 305, intake air may flow around the e-compressor 202 before passing through the turbocharger compressor 262 and the CAC 263.

the length of recirculation passage 302 may be longer than recirculation passage 208 of fig. 2 to allow air to recirculate from downstream of CAC 263 rather than upstream of CAC 263. By warming the air that has passed through CAC 263, the temperature of the air delivered to intake manifold 44 may be controlled with greater precision than the configuration of recirculation passage 208 of FIG. 2. Furthermore, when engine 10 is fitted with recirculation passage 302 of FIG. 3, control of temperature may be independent of the degree of load shifting.

The engine 10 may be configured with an electrically assisted boost system, as shown in the embodiment 400 of fig. 4 and the embodiment 500 of fig. 5, respectively, that includes an e-booster 402 positioned downstream of both the turbocharger compressor 462 and the CAC463 and driven by an electric motor 465. Similar to the mass flow sensor 220 of fig. 2-3, a mass flow sensor 420 is disposed immediately downstream of the e-supercharger 402 to monitor the mass flow rate at the outlet of the e-supercharger 402. As shown in fig. 4, the e-booster 402 may be adapted with a recirculation passage 404 and a recirculation valve 406, which operate similarly to the recirculation passage 208 and recirculation valve 210 of fig. 2. Intake air flowing into intake plenum 42 may be compressed by turbocharger compressor 462 and continue to flow through CAC463 when bypass valve 214 of CAC bypass 212 is closed. When recirculation valve 406 is open, bypass valve 214 may be instructed to open. When bypass valve 214 is open, at least a portion of the intake air may be diverted through CAC bypass 212 so that the air is not cooled by CAC 463.

Intake air flows from turbocharger compressor 462 through or around CAC463 and into e-supercharger 402. When recirculation valve 406 is at least partially open, a portion of the charge air exiting the e-supercharger that exceeds the boost demand of engine 10 may be recirculated through recirculation passage 404. Similar to recirculation valve 210 of fig. 4, recirculation valve 210 may be adapted to alternate between a fully open position and a fully closed position, or may be continuously adjusted to any position between fully open and fully closed. The compressed and warmed intake air may flow through an opening of throttle 62 to intake manifold 44 for combustion at cylinders 30.

In the embodiments 200, 300, 400, and 500 of engine 10 shown in fig. 2-5, respectively, throttle 62 may be a flow restrictor that controls the mass flow rate of air to engine 10. Isenthalpic expansion of the air may reduce the pressure and density of the air downstream of throttle 62, but maintain the temperature of the air through the throttling process. The flow restriction generated by throttle 62 may be adjusted in accordance with the adjustment of recirculation valve 406 to maintain the desired pressure and mass flow rate to intake manifold 44.

Peak combustion gas temperatures may also increase due to higher intake air temperatures and load shifting. Although higher combustion gas temperatures may exacerbate NO_XBut due to exhaust of gasesFaster catalyst light-off due to heating of the exhaust 71 shortens the period of time that the catalyst has not been activated, thereby shortening the NO_XAnd other combustion product emissions are the highest initial warm-up period.

In the embodiment 500 of the engine 10 in fig. 5, the turbocharger compressor 462, CAC463, CAC bypass 212 and bypass valve 214, and e-supercharger 402 are oriented similarly to those in fig. 4. However, in fig. 5, recirculation passage 502 may couple the region of boost chamber 46 upstream of turbocharger compressor 462 and CAC bypass 212 at CAC463 to the region between e-booster 402 and throttle 62. Flow through the recirculation passage 502 may be controlled by a recirculation valve 504, which recirculation valve 504, when opened, allows air downstream of the e-booster 502 to return to the area between the turbocharger compressor 462 and the CAC 463. The recirculated air may be a small portion of the intake air that exceeds the boost demand. The recirculation of intake air through the e-supercharger 502 increases the temperature of the air, thereby accelerating engine warm-up and catalyst light-off.

An e-booster bypass 503, fitted with an e-booster bypass valve 505, may branch from recirculation passage 502, coupling a region of recirculation passage 502 downstream of recirculation valve 504 to a region of boost chamber 46 downstream of CAC bypass 212 and upstream of turbocharger compressor 462. Similar to e-compressor bypass 303 and e-compressor bypass valve 305 of FIG. 3, when the e-supercharger 502 is inactive and the recirculation valve 504 is closed, the e-supercharger bypass valve 505 may be opened to divert intake air that has been cooled by the CAC463 around the e-supercharger 502 so that the intake air is not restricted by the e-supercharger 502.

The arrangement of recirculation passage 502 of FIG. 5 may allow at least a portion of the intake air to be cooled by CAC 163 to counteract heating of the intake air caused by recirculation. The configuration of recirculation passage 404 of FIG. 4 may provide enhanced maintenance of the temperature of the air delivered to intake manifold 44 via throttle 62. However, the arrangement of the recirculation passage 404 may not control the temperature of the air produced from the e-compressor outlet that is delivered to the intake manifold. The temperature of the air entering the intake manifold may be affected by variables such as thermal performance of components, compressor fouling, and exhaust knock. By configuring the recirculation passage 502 of FIG. 5 to return air upstream of the CAC 153, the recirculation valve may be adjusted in conjunction with the bypass valve 214 to achieve a desired air temperature depending on the current operating conditions.

The e-compressor positioned upstream of the turbocharger compressor (as shown in fig. 2 and 3), or downstream of the turbocharger compressor as the e-supercharger 402 (as shown in fig. 4 and 5), may operate at different efficiency levels. Placing the e-compressor upstream of the turbocharger compressor may provide an unrestricted intake air flow to the e-compressor inlet, thereby rapidly recirculating the intake air. However, when the e-compressor is positioned downstream of the turbocharger compressor, the amount of intake air may be constrained by the airflow through the stationary turbocharger compressor, thus reducing the rate of recirculation and heat transfer to the intake air.

The embodiments of the engine shown in fig. 2-5 may have similar effects on intake and exhaust temperatures, although the positioning of the elements relative to each other may differ, such as relative to the turbocharger compressor and the recirculation passages and compressor of the CAC (e.g., an e-compressor or e-supercharger). The recirculation of air through the compressor adds energy to the intake air through work transfer, and load transfer (increased engine load) increases exhaust temperature and mass flow rate through the engine. The power input into the compressor may be determined according to the following equation:

Where E is the energy, t is the time,Is the rate of heat transfer and is,Is the power, i.e., work transfer rate,Is the mass flow rate into the compressor and,Is the mass flow out of the compressor, h_Intois the enthalpy of inhalation and h_{Go out}Is the enthalpy of discharge. Assuming adiabatic, steady-state, steady-flow operation with constant specific heat, the compressor input power can be described as:

wherein T is_IntoIs the inlet temperature of the compressor, and T_{Go out}Is the outlet temperature of the compressor, and c_pIs the specific heat of air. Isentropic outlet temperature T_{Out of s}and inlet temperature T_IntoThe adiabatic and reversible polytropic processes are related:

Where gamma is the ratio of the specific heats relating to adiabatic and reversible processes and p_IntoIs the pressure at the inlet of the compressor, and p_{Go out}Is the pressure at the outlet of the compressor. May be based on the efficiency η of the compressor_cTo obtain the actual outlet temperature T of the compressor concerned_{Go out}。

Where Wc, s is the isentropic work input to the compressor and W_cIs the actual work input into the compressor.

From these relationships (e.g., Eq. 1-Eq. 4), the input power may be determinedand actual compressor outlet temperature (T)_{Go out}) To the mass flow of air entering the compressorAnd the outlet of the compressorDependence of the pressure at the port, wherein the inlet temperature and the inlet pressure of the compressor are kept constant. The outlet temperature may increase as the outlet pressure increases, and the compressor input power may increase as the mass flow rate into the compressor increases. The outlet pressure may be controlled by the input power provided to the compressor by the motor, and the mass flow into the compressor may be adjusted by a throttle (e.g., throttle 62 of fig. 1-5) and the compressor load provided by the motor and the opening of the recirculation valve. Thus, the combination of input power and throttling may be used to tune compressor operation into a high efficiency region while achieving a desired work transfer from the compressor to the intake air.

The estimated values for work transfer and compressor outlet temperature may represent a theoretical maximum amount of work transfer and temperature increase based on input power from the motor under ideal conditions. Under actual operating conditions, some losses may occur, such as heat transfer or frictional losses from surfaces of engine components, but work input may additionally be taken from the turbocharger compressor, and may also be placed in the intake flow path upstream or downstream of the electric compressor.

Alternatively, if the input power supplied to the compressor is kept constant, the compressor outlet temperature and pressure can be increased by decreasing the mass flow rate into the compressor. This may occur due to a tradeoff between mass flow rate and temperature gradient across the compressor to obtain a uniform amount of input power, as shown in equation 2. Thus, throttling may allow the compressor outlet to reach a desired temperature when a consistent input power is to be supplied to the compressor such that the compressor spins at a steady speed.

Based on the above-described method for adjusting the transfer of work from the electrically-driven compressor to the intake air, the size of the compressor may be modified. The compressor may be reduced in size and configured to generate higher pressure ratios at lower mass flow rates than typical e-compressors and e-superchargers. Adapting the compressor to devices such as active casing treatments and/or variable inlet compressors can expand compressor map width and help improve compressor performance to allow low mass flow, high pressure ratio operation, and high pressure ratio at high mass flow, set input power to speed engine heating and catalyst light-off.

When the CAC bypass valve is used to recirculate and heat intake air to direct at least a portion of the intake air around the CAC, the e-compressor or e-supercharger can still provide the amount of boost required for vehicle operation and introduce other beneficial effects on engine performance. For example, the heated intake air may reduce ignition delay in a diesel engine, thereby reducing the amount of premixed combustion and reducing the likelihood of NVH issues. It is possible to increase the peak combustion gas temperature and reduce the possibility of incomplete combustion, as well as reduce cycle variation. During engine cold starts, the diesel compression ratio is typically maintained above a desired value, but may be adjusted to a lower ratio when the intake air is heated by recirculation. For gasoline fueled engines, preheating the intake air may increase the flame speed, thereby improving cycle variation and reducing NVH issues and engine misfire.

In another example, the compressor may act as an electrical load on the vehicle battery, allowing the engine to operate at higher loads than those due to traction and auxiliary loads even with a fully charged battery. With a hybrid powertrain, the resulting load transfer effect can increase exhaust enthalpy and temperature, as well as mass flow rate, for both gasoline and diesel engines. Furthermore, although electrically driven compressors negatively impact the pressure ratio across the intake and exhaust manifolds, intake throttling of diesel engines may allow uncooled HP-EGR to be used. Uncooled HP-EGR may also raise the temperature of the intake air to increase combustion stability and increase the temperature of residual exhaust gas and EGR, which additionally contributes to combustion stability and higher exhaust gas temperatures.

examples of methods for operating an engine system of a hybrid vehicle are illustrated by method 600 in FIG. 6 and method 700 in FIG. 7. Method 600 shows a routine for warming intake air prior to engine cold start, and method 700 shows a routine for engine operation during a warm start. The intake system of the engine includes an electric motor driven compressor (e-compressor), such as e-compressor 202 of fig. 2-3 and e-supercharger 402 of fig. 4-5, positioned upstream or downstream of a turbocharger compressor and a Charge Air Cooler (CAC) in the intake passage. An exhaust device, such as exhaust device 71 of fig. 1-5, may be disposed in an exhaust system of the engine downstream of a combustion chamber of the engine. A recirculation passage having a recirculation valve (e.g., recirculation valve 210, 304, 406, or 504) may couple a region of the intake passage downstream of the e-compressor to a region of the intake passage upstream of the e-compressor, allowing air to be returned from an outlet of the e-compressor to an inlet of the e-compressor. The air flowing through the recirculation passage may be recirculated only through the e-compressor or both the e-compressor and the turbocharger compressor. The CAC may be fitted with a CAC bypass and a bypass valve to divert at least a portion of the intake air around the CAC. The instructions for implementing the methods 600 and 700, as well as the remaining methods included herein, may be executed by a controller based on instructions stored on a memory of the controller (such as the controller 12 of fig. 1) in conjunction with signals received from sensors of an engine system (such as the sensors described above with reference to fig. 1). The controller may employ an engine actuator of the engine system to adjust engine operation according to the method described below.

At 602, the method includes determining whether the engine is on, e.g., whether the engine is combusting air and fuel. If the engine is on, the method moves to method 700 of FIG. 7. If the engine is not on, the method proceeds to 604.

At 604, the method includes determining whether a start of the engine is imminent. The predicted engine start may be based on an instructional action, such as an operator opening a driver-side door of the vehicle or an operator sitting in a driver seat. In other examples, insertion of a key into a vehicle door or ignition of the engine (e.g., an ignition event, a manual trigger such as a button or switch, or remote activation) may indicate that the engine is to be turned on. In further examples, an impending engine start may be determined based on a preset operator schedule. For example, the operator may enter the engine start time into the schedule via a user interface of the vehicle or via a remote device in communication with the vehicle (e.g., via a smartphone). If no indication is provided that an engine start is imminent, method 600 returns to the beginning of the method. However, if engine activation is expected, the method continues to 606 to determine whether the engine is in a cold start.

Determining whether the engine start is a cold start may include comparing a manifold boost temperature, a coolant temperature, or a cylinder temperature measured by an intake air temperature sensor, such as sensor 121 of fig. 1, to a minimum temperature. The minimum temperature may be a temperature representing the low end of the engine operating temperature range, such as 90 ℃, or a temperature within a threshold (e.g., within 10%) of the engine operating temperature at idle. In another example, an engine cold start may be indicated when the engine temperature (e.g., as measured by engine coolant temperature) is equal to ambient temperature. Alternatively, the engine cold start may be determined based on the ambient temperature and the elapsed duration since the last engine operation.

The engine start may be a cold start due to the engine cooling down during a period of time when the engine is at rest and shut down. The rate at which cooling occurs may depend on the ambient temperature or the time since the last activity of the engine. The engine may also be in a cold start state when the vehicle is a hybrid vehicle and is operating in an electric propulsion mode with the engine off. This may occur when the vehicle is stationary and idling or during cruising when the engine load is low. If the engine is shut down for an extended period of time, the engine may cool below a minimum temperature for a non-cold start. The hybrid engine may be adapted to activate the e-compressor and heat the intake air during idle or cruise operation to reduce delays in engine performance due to warm-up.

If the engine is not in a cold start state, method 600 moves to 608 to initiate the engine start without delay after the non-cold start procedure. The non-cold start procedure may include cranking the engine with the starter motor immediately upon detecting: the MCT, for example, is above a minimum temperature, flows intake air to a combustion chamber of the engine, and injects fuel. The air/fuel mixture is ignited in the combustion chamber, drives rotation of the crankshaft, and powers movement of the vehicle once the transmission is shifted to drive the gears. If a cold start is confirmed at 606, the method proceeds to 610 to check the state of charge (e.g., power level) of the vehicle battery (such as battery 8 of FIG. 1).

The controller may compare the detected state of charge to a minimum charge sufficient to power the electric machine to operate the e-compressor and switch on the engine. If the battery does not have sufficient stored energy to perform such an operation, the method does not warm up the intake air prior to engine start. If the battery is charged sufficiently to meet or exceed the minimum power amount, the method proceeds to 612.

At 612 of the method, a motor is activated to power rotation of an e-compressor. The method continues to 614 to at least partially open the recirculation valve (e.g., open the recirculation valve to a fully open position or to a position between fully open and fully closed), and open a bypass valve of the CAC bypass, such as valve 214. Intake air flows through the recirculation passage at 616 in a direction opposite to the flow through the intake passage, returning to the inlet of the e-compressor to be further compressed and warmed.

As air is recirculated through the recirculation channel, the mass flow rate may be measured at the e-compressor outlet by a mass flow sensor, such as mass flow sensor 220 of fig. 2-3 and mass flow sensor 420 of fig. 4-5. The controller may use the mass flow rate to estimate a period of time that allows the intake air to recirculate through the e-compressor a sufficient number of times to heat the intake air to a desired temperature for warming the engine cylinders. Alternatively, the mass flow rate may be used to adjust a recirculation valve to increase or decrease the flow through the e-compressor to achieve a desired intake air temperature.

at 618, the method includes comparing the temperature at the outlet of the e-compressor to a first threshold temperature. The first threshold temperature may be the lowest temperature to which the recirculated air is heated in order to transfer sufficient heat to the intake manifold and the combustion cylinders to raise the exhaust gas temperature. The exhaust gas may transfer heat to the exhaust, and the resulting temperature increase of the exhaust may allow catalyst light-off to occur in a shorter duration. In one example, the first threshold temperature at the e-compressor outlet may be 150 ℃.

If the e-compressor outlet temperature has not reached the first threshold temperature, the method returns to 616 to continue heating the intake air by flowing the intake air through the recirculation passage to return the intake air to the e-compressor inlet. If the outlet temperature meets or exceeds the first threshold temperature, the method proceeds to 620 to turn on the engine. Starting the engine includes cranking the engine and initiating combustion of air and fuel at the combustion chamber. In another example, the controller may indicate that the engine is ready to turn on based on the detected manifold charge air temperature (MCT) reaching a preset temperature estimated to increase the exhaust temperature sufficiently to promote rapid catalyst light-off. Alternatively, during any indication that an engine start is about to occur, as described above, a preset time delay may be included to accommodate activation of the e-compressor and sufficient heating of the intake air prior to performing the engine cranking. Monitoring of the mass flow rate at the e-compressor outlet may be used to adjust the intake throttle to increase the mass flow based on a temperature deficit between the measured outlet temperature of the e-compressor and the first temperature threshold. The mass flow rate is adjusted to ensure adequate heating of the intake air during the amount of time allotted for recirculation and heating before the engine is turned on.

during engine cranking, the opening of the recirculation valve of the recirculation passage may be briefly reduced or closed to increase the intake air flow into the combustion chamber during ignition, thereby reducing the likelihood of the engine being starved of oxygen (e.g., fuel rich operation). Once the engine is on, the opening of the recirculation valve may be increased or decreased at 622 according to fluctuations that occur during the initial stages of engine activation. When combustion is stable, the recirculation valve may be adjusted based on a target air-fuel ratio at the cylinder in combination with a desired mass flow rate through the e-compressor to achieve a desired increase in intake manifold temperature.

The adjustment of the mass flow and the delivery of intake air to the combustion cylinder may also be controlled by an intake throttle valve. The opening of the throttle valve may be adjusted at 624 in conjunction with a recirculation valve to provide a desired mass flow rate during engine cranking and combustion. However, throttling to achieve higher intake manifold temperatures may result in parasitic loading of the e-compressor due to increased e-compressor outlet pressure, which may reduce vehicle efficiency but facilitate catalyst light-off times. Throttle and recirculation valve positions may be balanced to provide load shifting that reduces energy consumption while adequately heating the exhaust.

Initially, the throttle valve may be set to an idle position where the throttle valve is slightly open at engine start. With the engine open, the controller may command adjustment of the throttle position based on a desired mass flow rate through the e-compressor. The power input from the electric machine to the e-compressor may be simultaneously adjusted such that the combination of the mass flow rate and the pressure ratio of the compressor (where the pressure ratio is a function of the power input to the e-compressor and the work transfer from the e-compressor to the air) allows the compressor to operate in an efficient region while providing the desired amount of heating to the engine intake and exhaust.

for example, the throttle may be adjusted to achieve a desired air mass flow rate to the engine. The controller may refer to a look-up table having mass flow rates that may be measured by a mass flow sensor in the intake manifold with a preset manifold pressure as an input and a system pressure (e.g., a pressure ratio or differential pressure between the exhaust and intake manifolds) as an output. The system pressure may be compared to a predetermined pressure that allows for the use of HP-EGR, and the throttle opening and the recirculation valve opening may be adjusted to achieve the desired system pressure.

At 626, the method includes comparing a temperature of the transmitting device (EDT) to a second threshold temperature. The EDT increases due to combustion of the heated intake air in the combustion chamber, producing hotter exhaust gases. The temperature of the second threshold may be based on an estimated minimum temperature of the exhaust to improve combustion efficiency and stability in the combustion chamber to reduce incomplete combustion and vehicle NVH issues and faster catalyst light-off. In other examples, the temperature at the combustion chamber may be measured and similarly compared to a threshold temperature. The threshold temperature may be a temperature indicative of an increased peak combustion gas temperature that allows complete and stable combustion and results in the generation of sufficiently hot exhaust gas to accelerate catalyst light-off.

If the EDT does not reach the second threshold temperature, the method returns to 622 to adjust the recirculation valve to increase or maintain heating of the intake air through the e-compressor with the CAC bypass open. If the EDT matches or exceeds the second threshold temperature, the method proceeds to 628 to deactivate the e-compressor and close the recirculation valve. In the engine configurations of fig. 2 and 4, the CAC bypass valve may be closed, or the opening may be decreased to allow the CAC to cool and increase the density of the boosted intake air to increase the combustion efficiency and power output of the engine after the initial warm-up of the intake manifold has been achieved. The recirculation valve may remain open to allow intake air to flow around the inactive e-compressor so that airflow to the intake manifold is not restricted by the e-compressor.

Alternatively, for the engine configurations of FIGS. 3 and 5, the recirculation valve may be closed and the e-compressor bypass valve opened to allow the intake air to be diverted around the e-compressor so that the airflow is not limited to the intake manifold. The air is cooled by the CAC either before (as shown in fig. 5) or after (as shown in fig. 3) flowing through the e-compressor bypass. In addition, the exhaust pressure may be increased sufficiently to drive rotation of an exhaust turbine of the turbocharger. Thus, the turbocharger compressor may supply sufficient torque to meet the torque demand, and the e-compressor may be deactivated. The method may return to 602 to continuously monitor engine conditions and temperatures of the intake manifold, combustion chambers, and exhaust devices to operate the e-compressor according to the parameters.

If the torque demand exceeds the amount of boost provided by the turbocharger compressor, the e-compressor may be reactivated with the recirculation valve closed. Insufficient torque may be addressed by additional compression of the intake air by the e-compressor. Additionally, if the EDT is detected to be below a second threshold temperature, the e-compressor may be reactivated and the recirculation valve opened. During conditions where insufficient torque is detected and EDT falls below the second threshold temperature, priority may be given to accommodating insufficient torque and generating additional boost with the recirculation valve closed.

In some examples, the e-compressor may be enabled to manage air mass flow rate/energy release rate (e.g., fueling) independent of operation of the turbocharger and/or throttle position in an active DPF or lean GPF system. In the event of a thermal runaway of the active DPF, the e-compressor may act as a protection device, which may occur during accelerator pedal release when the air mass flow rate within the DPF is insufficient to control the increase in filter and housing temperatures.

Returning now to FIG. 7, at 702 of method 700, the MCT may be compared to a first threshold temperature. The first threshold temperature may be based on a temperature at which a combustion cylinder of the engine is sufficiently heated to provide stable and complete combustion, resulting in reduced NVH issues and generation of sufficiently hot exhaust gas to maintain the exhaust at or above the light-off temperature. In another example, the temperature of the combustor or exhaust may be compared to a threshold temperature instead of MCT, which similarly allows for increased combustion stability and EDT to maintain catalyst activity.

If the MCT is below the first threshold temperature, the method proceeds to 704 to adjust operation of the e-compressor based on the MCT. For example, the controller may command actuation of the e-compressor and opening of a recirculation valve of the recirculation passage. With the bypass valve of the CAC bypass also open, air may be recirculated through the e-compressor until the MCT reaches the first threshold temperature. At 706, HP-EGR may flow during heating of the intake air via recirculation. While HP-EGR may not flow during charge air in a typical e-booster turbocharger engine system, throttling of recirculated intake air to achieve a desired work transfer from the e-compressor to the intake air may provide a pressure gradient between the intake manifold and the exhaust manifold that allows concurrent HP-EGR flow. The method can return to the beginning to again compare the MCT to the first threshold.

Returning to 702, if the MCT is at least equal to the first threshold temperature, method 700 continues to 708 where operation of the e-compressor is adjusted based on the boost demand. For example, the boost demand may be indicated by a position of an input, such as accelerator pedal 130 of FIG. 1. If the boost demand exceeds that provided by the turbocharger compressor, the electric machine may power rotation of the e-compressor and spin the e-compressor at a speed that accommodates insufficient boost. At 710, the method includes determining whether regeneration of a Particulate Filter (PF) is indicated. The indication of the request for regeneration of the PF may include detecting that the particulate matter load of the PF reaches a preset maximum load, such as 90% of the maximum load, which may be detected based on a pressure drop across the particulate filter. However, if PF regeneration is not indicated, the method proceeds to 712 to continue engine operation according to the current boost demand, engine load, engine speed, and the like.

If PF regeneration is desired, the method proceeds to 714 to actuate the e-compressor via power input from the electric machine and open the recirculation valve of the recirculation passage. The CAC bypass valve is also opened to allow recirculation of intake air through the e-compressor to heat the intake air by work transfer from the e-compressor, while bypassing at least a portion of the intake air around the CAC to reduce the cooling effect of the CAC on the air. A post injection event may occur in the combustion chamber where fuel is injected into the combustion chamber but not combusted. Unburned fuel is delivered to the exhaust, where the fuel is a reductant when heated, helping to oxidize particulate matter trapped in the PF. Additionally, HP-EGR may flow when the e-compressor is active and the recirculation valve is open.

in some examples, charge air provided by a turbocharger compressor may be used to initiate PF regeneration. However, vehicle tip-out during regeneration may occur, resulting in insufficient air being supplied to the PF from the turbocharger compressor. The e-compressor may be activated to supplement the airflow for regeneration of the PF, with the recirculation valve closed to pool all of the compressed air to the engine. Additionally, excess fuel may be injected to facilitate active regeneration in response to additional airflow, thereby allowing adjustment of PF temperature and mitigating excess filter load.

At 716 of the method 700, the PF temperature may be compared to a second threshold temperature. The second threshold temperature may be a regeneration temperature of the PF, such as 600 ℃. If the PF is below a second threshold temperature, the method returns to 714 to continue heating the combustion chamber by heating the intake air via recirculation through the e-compressor and flowing HP-EGR. If the PF is at least equal to the second threshold temperature, the method continues to 718.

At 718, the method includes, after maintaining the temperature of the PF at or above the second temperature threshold for a preset period of time sufficient for regeneration of the PF, closing the recirculation valve, adjusting the CAC bypass valve to provide a desired amount of cooling to the charge air, and adjusting the e-compressor operation. Adjusting e-compressor operation may include: the e-compressor is deactivated if the turbocharger compressor meets the boost demand, or is rotated at a speed that matches the boost deficit if the boost demand exceeds the boost supplied from the turbocharger compressor. HP-EGR may be terminated if the e-compressor remains in operation, or flow may continue if boost demand is low and the e-compressor is deactivated. After 718, the method returns to 702 to continue monitoring the MCT and adjusting engine operation accordingly.

FIG. 8 illustrates an exemplary operating map 800 for a hybrid engine system in a cold start condition, including engine load (curve 802), e-compressor speed (curve 804), position of the recirculation valve of the recirculation passage around the e-compressor (curve 806), position of the CAC bypass valve of the CAC bypass passage (curve 808), position of the intake throttle (curve 810), manifold boost temperature (MCT, curve 812), and temperature at the outlet of the e-compressor (curve 814). The MCT at curve 812 includes an MCT threshold temperature (line 816) that represents the minimum temperature to which the MCT can be heated, which improves combustion completeness and stability and allows the exhaust temperature to increase. The outlet temperature of the e-compressor at curve 814 may include an outlet threshold temperature (line 818) representing the temperature of the intake air recirculated through the e-compressor that is heated sufficiently to raise the temperature of the MCT to the MCT threshold temperature.

The x-axis of the graph in FIG. 8 represents time, and the time increases from left to right as shown by the arrowsAnd (4) adding. At time T₀Previously, the engine was unloaded and the e-compressor was at rest, the recirculation valve and CAC bypass valve were closed, the throttle valve was closed, and the MCT and e-compressor outlet temperatures were low, well below the MCT and outlet temperature thresholds.

At T₀And heating of the intake air is started. The controller commands intake air heating due to impending engine start indicated by detection of MCT being below a temperature that allows complete and stable combustion and/or below a temperature that produces exhaust gas temperatures high enough to promote catalyst light-off at the exhaust. The motor powers the e-compressor, thereby accelerating the rotation of the e-compressor and increasing the speed of the e-compressor at T₀And T₁The velocity in between. The recirculation valve opens allowing the intake air to return from downstream of the e-compressor to the inlet of the e-compressor and heat, while the CAC bypass valve opens to bypass at least a portion of the heated intake air around the CAC. Throttle valve at T₀And T₁Is kept closed. When the e-compressor outlet temperature is at T₀MCT remains low when there is an increase in MCT.

At T₁And e-the compressor outlet temperature reaches the outlet temperature threshold. Detection of the e-compressor outlet temperature reaching the threshold triggers cranking of the engine and the engine load rises. The speed of the e-compressor remains relatively constant, but the opening of the recirculation valve is decreased to increase the amount of intake air delivered to the engine intake manifold. The amount of boost imparted to the intake air by recirculation through the e-compressor exceeds the boost demand of the engine. The CAC bypass valve is maintained open while the throttle opening is increased to an idle position to deliver intake air to the combustion chamber. The MCT begins to rise while the rate of rise of the e-compressor outlet temperature decreases.

At T₁And T₂In between, the recirculation valve is further opened to reduce the flow to the engine, thereby preventing the heated compressed intake air from flowing excessively into the combustion chamber, which may overload the engine. The change in flow may result in an under-load of the engine, which is addressed by simply reducing the opening of the recirculation valve. The recirculation valve opening increases as the engine load stabilizes.

Adjusting the recirculation valve in response to engine load may be particularly advantageous for spark-ignition engines. However, for diesel engines, the air-fuel ratio may be made rich (if not at a rich limit) by injecting more fuel so as to reduce the beneficial effects of the recirculation valve adjustment. The recirculation valve may be used with a more closed throttle position to achieve higher intake manifold temperatures to promote aftertreatment light-off. However, this may occur at the expense of increased e-compressor/turbine parasitic load (due to increased e-compressor/turbine outlet pressure), which reduces vehicle efficiency but may shift engine load to higher loads, thereby facilitating aftertreatment light-off times. A balance between throttle and recirculation valve positions and load shifting may be found to minimize energy consumption while achieving desired aftertreatment-out emission levels to meet emission requirements.

At T₂The MCT reaches an MCT threshold temperature. e-the compressor is deactivated and decelerated to become stationary. The recirculation valve is closed and the opening of the CAC bypass valve is decreased to provide increased charge air cooling. When the engine load remains stable, the throttle opening is increased. The MCT remains above the MCT threshold as the e-compressor outlet temperature is gradually decreased.

e-compressor at T in response to engine load increase₃Is deactivated. The torque request is greater than the amount of boost provided by the turbocharger compressor, and the electric machine is instructed to operate the e-compressor to assist the turbocharger compressor in compressing the intake air. e-speed of compressor at T₃And T₄And the CAC bypass valve is closed to allow the CAC to cool and increase the density of the charge air. The recirculation valve remains closed and the throttle valve is opened to increase the mass flow through the intake system and to the engine. At T₃And T₄In between, the MCT and outlet temperatures of the e-compressor increase.

At T₄The engine load begins to decrease, resulting in a decrease in torque demand. The torque demand is reduced sufficiently to enable the turbocharger compressor to supply the desired amount of boost to the engine without the aid of the e-compressor. e-compressor deactivation, decelerating until stop. CAC bypass valve is maintained closed and throttledthe opening of the valve is decreased to adjust the mass flow rate to the engine according to the torque demand. For an engine configuration similar to that of fig. 2 and 4, the recirculation valve is open, while for the engine configuration of fig. 3 and 5, the recirculation valve is closed. For the configuration of fig. 3 and 5, the e-compressor bypass valve is open. The MCT remains relatively high but decreases slightly while the e-compressor exit temperature decreases at a faster rate.

In this manner, an electrically driven compressor (e-compressor) may be positioned in the intake passage of the hybrid vehicle and used to enhance warm-up of the engine and exhaust during engine cold starts. The e-compressor may be arranged upstream or downstream of the turbocharger compressor, or may alternatively be the compressor of an electric turbocharger. The recirculation passage may couple a region of the intake passage downstream of the e-compressor outlet to a region of the intake passage upstream of the e-compressor inlet. When the e-compressor is actuated and the recirculation valve of the recirculation passage is open, intake air may flow from downstream of the e-compressor to upstream of the e-compressor to recirculate air through the e-compressor. Work transfer from the e-compressor to the intake air heats the air, and warmer intake air may result in increased combustion efficiency and also increase exhaust gas temperature when the heated intake air is delivered to the combustion chamber of the engine. The higher exhaust temperature heats the exhaust, which is located downstream of the combustion chamber in the exhaust system coupled to the combustion chamber, thereby reducing the light-off time of the exhaust. The efficiency of the emissions device increases during the initial phase of engine start-up, reducing the release of undesirable materials to the atmosphere. Further, heating the intake air by recirculation through the e-compressor may facilitate regeneration of a gas particulate filter or a diesel particulate filter in the exhaust while allowing HP-EGR flow. Accordingly, accelerated engine and exhaust warm-up is achieved using the electrical system already present in hybrid vehicles that powers the e-compressor.

the technical effect of adapting a hybrid electric vehicle with a recirculation passage around the electric compressor is to reduce the duration of engine warm-up and catalyst light-off, and to improve combustion efficiency and exhaust emissions management during engine cold starts.

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 may be implemented 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. To this extent, 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 the engine control system, with the described acts being implemented by executing instructions in the system including the various engine hardware components and the electronic controller.

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 cylinders, inline 4 cylinders, inline 6 cylinders, V-12 cylinders, opposed 4 cylinders, and other engine types. The subject matter of the present disclosure includes all novel and nonobvious combinations and subcombinations of the various systems and configurations, and other features, functions, and/or properties disclosed herein.

In one embodiment, a method comprises: prior to an engine cold start, operating an e-compressor and opening a recirculation valve of a recirculation passage coupled to the e-compressor to flow compressed intake air from an outlet of the e-compressor to an inlet of the e-compressor through the recirculation passage; and starting the engine when the temperature at the outlet of the e-compressor reaches a threshold value and continuing to operate the e-compressor while the engine is turned on. A first example of the method includes opening a bypass valve of a bypass passage of a Charge Air Cooler (CAC) disposed in the intake passage to allow a portion of the intake air to flow through the bypass passage. A second example of the method optionally includes the first method and further includes wherein operating the e-compressor prior to the engine cold start includes activating the e-compressor when a temperature of the intake manifold is below a threshold temperature. A third example of the method optionally includes one or more of the first example and the second example, and further includes wherein operating the e-compressor when the engine is on generates an e-compressor load that exceeds an e-compressor load required to meet the torque demand. A fourth example of the method optionally includes one or more of the first to third examples, and further comprising wherein operating the e-compressor comprises powering rotation of the e-compressor by an electric machine that receives energy from an electrical system of the engine, an amount of power supplied by the electric machine being based on a desired mass air flow rate of the intake air and a pressure of an intake manifold located downstream of the e-compressor. A fifth embodiment of the method optionally includes one or more of the first through fourth examples, and further includes: adjusting an amount of power supplied by the motor based on a threshold temperature at an outlet of the e-compressor. A sixth example of the method optionally includes one or more of the first to fifth examples, and further comprising wherein starting the engine comprises flowing recirculated heated intake air from the outlet of the e-compressor to the engine and initiating combustion of the intake air in the engine, thereby heating the engine. A seventh example of the method optionally includes one or more of the first through sixth examples, and further comprising, when the engine is turned on, directing exhaust from the engine to one or more exhaust devices and adjusting a recirculation valve based on a temperature of the one or more exhaust devices. An eighth example of the method optionally includes one or more of the first through seventh examples, and further includes: when the engine is turned on, the intake throttle is adjusted in response to the amount of work transferred from the e-compressor to the intake to adjust the mass flow through the e-compressor to increase combustion and exhaust temperatures. A ninth example of the method optionally includes one or more of the first through eighth examples, and further includes: operating the e-compressor and opening a bypass valve of a bypass passage of the charge air cooler in response to a command to regenerate the particulate filter.

By way of another embodiment, an engine system comprises: an intake system coupled to an exhaust system, wherein a combustion chamber is positioned between the intake system and the exhaust system; an intake passage of an intake system, the intake passage being located upstream of a combustion chamber, the intake passage being configured with an electrically driven compressor (e-compressor) and a Charge Air Cooler (CAC) arranged in an airflow path; a recirculation passage coupling a region of the intake passage downstream of the e-compressor to a region of the intake passage upstream of the e-compressor; an exhaust arrangement arranged in the exhaust system downstream of the combustion chamber; and a controller configured with computer readable instructions stored on non-transitory memory, the instructions being executable by the controller to delay combustion at the engine when a manifold boost temperature (MCT) is below a threshold temperature, operate the e-compressor, and flow air through a recirculation passage to heat the air, in response to an engine start request; and initiating combustion in the engine when the MCT is at least equal to the threshold temperature. In a first example of the system, the recirculation passage is configured to recirculate air from an outlet of the e-compressor to an inlet of the e-compressor. The second example of the system optionally includes the first example, and further includes wherein the recirculation passage is configured to recirculate air from a region of the intake passage downstream of the e-compressor and the CAC to a region of the intake passage upstream of the e-compressor and upstream of the CAC. A third example of the system optionally includes one or more of the first example and the second example, and further includes wherein the e-compressor is downstream of both the CAC and the turbocharger compressor. A fourth example of the system optionally includes one or more of the first to third examples, and further including wherein the e-compressor is upstream of both the CAC and the turbocharger compressor. A fifth embodiment of the system optionally includes one or more of the first through fourth embodiments, and further comprising, further comprising a recirculation valve disposed in the recirculation passage, and wherein the instructions are executable to open the recirculation valve when the MCT is below a threshold temperature, and close the recirculation valve when the MCT is at least equal to the threshold temperature. A sixth example of the system optionally includes one or more of the first through fifth examples, and further includes further including a CAC bypass valve configured to control flow through the CAC bypass channel, and wherein the instructions are executable to open the CAC bypass valve when the MCT is below the threshold temperature.

By way of another embodiment, a method comprises: responsive to the intake manifold temperature falling below a first threshold temperature, activating an electrically-driven compressor (e-compressor) disposed in the intake passage to flow a portion of the intake air through the e-compressor more than once via the recirculation passage by opening a recirculation valve of the recirculation passage; diverting air around a Charge Air Cooler (CAC) through a CAC bypass by opening a bypass valve of the CAC bypass, the CAC also being disposed in the intake passage; and throttling intake air delivered to a combustion chamber of the engine by adjusting an opening of a throttle valve disposed downstream of the e-compressor and the CAC and upstream of the combustion chamber in the intake passage. A first example of the method includes decreasing respective opening degrees of a recirculation valve and a bypass valve upon detecting an intake manifold temperature reaching a first threshold temperature. The second example of the method optionally includes the first example, and further comprising: the respective openings of the recirculation valve and the bypass valve are reduced upon detecting a temperature of an exhaust device positioned in an exhaust passage coupled to the combustion chamber reaching a second threshold temperature.

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.

According to the invention, a method comprises: prior to an engine cold start, operating an e-compressor and opening a recirculation valve of a recirculation passage coupled to the e-compressor to flow compressed intake air from an outlet of the e-compressor to an inlet of the e-compressor through the recirculation passage; and starting the engine when the temperature at the outlet of the e-compressor reaches a threshold value and continuing to operate the e-compressor while the engine is turned on.

According to one embodiment, the above invention is further characterized by opening a bypass valve of a bypass passage of a Charge Air Cooler (CAC) disposed in the intake passage to allow a portion of the intake air to flow through the bypass passage.

According to one embodiment, operating the e-compressor prior to the engine cold start includes activating the e-compressor when a temperature of the intake manifold is below a threshold temperature.

According to one embodiment, operating the e-compressor when the engine is on generates an e-compressor load that exceeds the e-compressor load required to meet the torque demand.

According to one embodiment, operating the e-compressor includes powering rotation of the e-compressor by an electric machine receiving energy from an electrical system of the engine, an amount of power supplied by the electric machine being based on a desired mass air flow rate of intake air and a pressure of an intake manifold located downstream of the e-compressor.

According to one embodiment, the above invention is further characterized by adjusting the amount of power supplied by the motor based on a threshold temperature at the outlet of the e-compressor.

According to one embodiment, starting the engine includes flowing recirculated heated intake air from the outlet of the e-compressor to the engine and initiating combustion of the intake air in the engine, thereby heating the engine.

according to one embodiment, the above invention is further characterized by directing exhaust from the engine to one or more exhaust devices and adjusting the recirculation valve based on a temperature of the one or more exhaust devices when the engine is turned on.

According to one embodiment, the above invention is further characterized by adjusting an intake throttle in response to an amount of work transfer from the e-compressor to the intake air to adjust a mass flow rate through the e-compressor to increase combustion temperature and exhaust temperature when the engine is turned on.

According to one embodiment, the above invention is further characterized by: operating the e-compressor and opening a bypass valve of a bypass passage of the charge air cooler in response to a command to regenerate the particulate filter.

according to the present invention, there is provided an engine system of a hybrid electric vehicle, the engine system having: an intake system coupled to an exhaust system, wherein a combustion chamber is positioned between the intake system and the exhaust system; an intake passage of an intake system, the intake passage being located upstream of a combustion chamber, the intake passage being configured with an electrically driven compressor (e-compressor) and a Charge Air Cooler (CAC) arranged in an airflow path; a recirculation passage coupling a region of the intake passage downstream of the e-compressor to a region of the intake passage upstream of the e-compressor; an exhaust arrangement arranged in the exhaust system downstream of the combustion chamber; and a controller configured with computer readable instructions stored on non-transitory memory, the instructions being executable by the controller to delay combustion at the engine when a manifold boost temperature (MCT) is below a threshold temperature, operate the e-compressor, and flow air through a recirculation passage to heat the air, in response to an engine start request; and initiating combustion in the engine when the MCT is at least equal to the threshold temperature.

According to one embodiment, the recirculation passage is configured to recirculate air from an outlet of the e-compressor to an inlet of the e-compressor.

According to one embodiment, the recirculation passage is configured to recirculate air from a region of the intake passage downstream of the e-compressor and the CAC to a region of the intake passage upstream of the e-compressor and the CAC.

According to one embodiment, the e-compressor is downstream of both the CAC and the turbocharger compressor.

According to one embodiment, the e-compressor is located upstream of both the CAC and the turbocharger compressor.

According to one embodiment, the above invention is further characterized by a recirculation valve disposed in the recirculation passage, and wherein the instructions are executable to open the recirculation valve when the MCT is below a threshold temperature, and close the recirculation valve when the MCT is at least equal to the threshold temperature.

According to one embodiment, the above invention also features a CAC bypass valve configured to control flow through the CAC bypass channel, and wherein the instructions are executable to open the CAC bypass valve when the MCT is below a threshold temperature.

According to the invention, a method for an engine comprises: responsive to the intake manifold temperature falling below a first threshold temperature, activating an electrically-driven compressor (e-compressor) disposed in the intake passage to flow a portion of the intake air through the e-compressor more than once via the recirculation passage by opening a recirculation valve of the recirculation passage; diverting air around a Charge Air Cooler (CAC) through a CAC bypass by opening a bypass valve of the CAC bypass, the CAC also being disposed in the intake passage; and throttling intake air delivered to a combustion chamber of the engine by adjusting an opening of a throttle valve disposed downstream of the e-compressor and the CAC and upstream of the combustion chamber in the intake passage.

According to one embodiment, the above invention is further characterized by decreasing respective opening degrees of the recirculation valve and the bypass valve upon detection of the intake manifold temperature reaching a first threshold temperature.

According to one embodiment, the above invention is further characterized by decreasing respective opening degrees of the recirculation valve and the bypass valve upon detecting a temperature of an exhaust device positioned in an exhaust passage coupled to the combustion chamber reaching a second threshold temperature.