Transition control apparatus and method for a multi-combustion mode engine in a hybrid electric vehicle

Abstract

Automotive designers are largely shifting from internal combustion engines to batteries and electric motors. Hybrid electric vehicles (HEVs), which combine an internal combustion engine and an electric motor, represent a step towards electrification and higher system fuel efficiency while maintaining the expected driving range, until the infrastructure supporting full electrification is developed. To achieve higher system fuel efficiency, HEVs can utilize combustion modes that offer higher efficiency than spark ignition (SI) operation. One problem with these combustion modes is that they cannot be used as widely as SI operation, and the transitions between modes are slow and cumbersome. By incorporating a multi-combustion-mode engine in a hybrid electric vehicle and coordinating smooth mode switching with an electric motor, highly fuel-efficient alternative combustion modes can be utilized while simultaneously providing the smooth operation expected by the vehicle's occupants.

Description

Technical Field

[0001] This disclosure relates to the switching of combustion modes in hybrid electric vehicle engines. Background Technology

[0002] Engines remain a vital power source in automotive transportation. Unfortunately, fossil fuels are major contributors to greenhouse gases, a primary cause of climate change. Vehicle electrification is rapidly advancing. To bridge the gap before widespread adoption of electric vehicles, efficient vehicles are still needed. Alternatively, by continuing to develop sustainable and economically competitive fuels, such as methanol or green hydrogen produced through solar or wind power electrolysis, engines may well remain on par with electric vehicles for a long time to come.

[0003] Most modern engines are either spark-ignition (SI) engines running on gasoline or compression-ignition (CI) engines running on diesel. While CI engines offer higher efficiency than SI engines, they suffer from emissions problems that are more difficult to address. In particular, they produce nitrogen oxides, which contribute to smog, and aftertreatment solutions using urea and traps are cumbersome. Furthermore, CI engines produce particulate matter, which must be collected in a particulate filter and regenerated; again, this is a troublesome solution.

[0004] Engines employing alternative combustion modes have been studied for many years. These include homogeneous charge compression ignition (HCCI) engines, controlled auto-ignition (CAI) engines, optimized power process (OKP) engines, and spark-assisted compression ignition (SACI) engines. While they have shown great promise in reducing CO2 (and improving fuel efficiency), none are well-suited to providing driving performance and functionality comparable to state-of-the-art vehicles across their entire operating range. In other words, engines operating using one of these alternative combustion modes typically produce only about half the power of those operating in conventional combustion modes (CI or SI). Therefore, it has long been recommended that vehicles operate in one of these alternative combustion modes whenever possible, switching to SI or CI when alternative combustion modes cannot provide a high-power operating range, thereby improving overall vehicle efficiency.

[0005] It is well known in the art that switching between engine combustion modes is difficult in conventional gasoline-powered vehicles. These difficulties include, for example, engine torque fluctuations, even incomplete combustion, and an unacceptably slow transition when the vehicle driver (whether human or autonomous) requests a change in operating point. Furthermore, not only is the transition slow, but it is also likely to result in unstable engine combustion during the transition. This is unacceptable for drivers of modern vehicles. In addition, unstable engine combustion leads to unacceptably high emissions. Therefore, systems and methods that achieve the advantages of efficient combustion modes without the disadvantages of such switching operations between combustion modes are needed. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, the engine (ICE) of a hybrid electric vehicle transitions between two combustion modes on command to a transition operating point between the current and new combustion modes. The transition operating point is a known stable operating point that allows the engine to make necessary adjustments to enter the new combustion mode. These necessary adjustments include one or more engine control units and parameter adjustments: intake pressure, intake temperature, compression ratio, valve timing, exhaust gas recirculation, etc. In a conventional internal combustion engine, without the assistance of an electric motor, the engine may fail to reach the transition operating point because the engine's output torque at that point may not match the driver's demand for driving torque. The decrease and increase in engine torque during the transition are completely unacceptable. However, in a hybrid electric vehicle, the electric motor and its electrically connected battery can be used to assist the engine in absorbing excess torque and providing insufficient torque, thereby meeting the driver's needs.

[0007] A method for developing combustion mode transitions to leverage the advantages of hybrid electric vehicles is disclosed herein. In a hybrid electric vehicle, the rotating shaft of an electric motor is mechanically connected to the crankshaft of an engine, and the battery is electrically connected to the motor. The method includes: determining when to instruct the engine to transition from the current combustion mode to the new combustion mode during a transition interval between the current and new combustion modes; selecting one of a plurality of predetermined combustion mode switching operating points for the engine to operate at during the transition interval; and instructing the engine to reach the selected predetermined combustion mode switching operating point during the transition interval. When the torque generated by the engine at the selected predetermined combustion mode switching operating point is insufficient, causing the engine speed to decrease, the electric motor acts as a motor and drives the engine, thereby maintaining the engine at the selected predetermined combustion mode switching operating point. When the torque generated by the engine at the selected predetermined combustion mode switching operating point is excessive, causing the engine speed to increase, the electric motor acts as a generator and loads the engine, thereby maintaining the engine at the selected predetermined combustion mode switching operating point.

[0008] During the transition interval, the engine prepares for operation in the new combustion mode. This preparation involves at least one of the following: heating or cooling the engine intake system (depending on the nature of the combustion mode the engine will enter), increasing or decreasing the engine intake system pressure, increasing or decreasing the proportion of exhaust gas introduced into the engine intake system, changing the engine compression ratio, changing the air-fuel ratio entering the engine, changing the engine fuel injection timing and injection quantity, changing the engine ignition timing, and changing the engine valve timing. Furthermore, depending on the change in combustion mode, the engine's fuel supply may be interrupted or restarted. This method also includes instructing the engine to operate in the new combustion mode after the preparation is completed.

[0009] The selected predetermined combustion mode switching operating point is based on the battery's state of charge. In some embodiments, the selected predetermined combustion mode switching operating point is further based on the expected time of the hybrid electric vehicle's torque demand and transition interval from the vehicle driver. The vehicle driver can be the person driving the hybrid electric vehicle, typically communicating via the accelerator pedal. Alternatively, the driver can be an autonomous controller within an automated driving controller.

[0010] The instruction to transition the engine from the current combustion mode to the new combustion mode is based on the fact that the hybrid electric vehicle operates more efficiently in the new combustion mode than in the current combustion mode.

[0011] The instruction to transition the engine from the current combustion mode to a new combustion mode is determined based on the battery's state of charge and the engine's appropriate temperature to support stable combustion in the new mode. In some embodiments, the engine should be adequately preheated during a cold start to transition to the new combustion mode. In other types of transitions, the engine temperature, particularly the intake air temperature, should be below a predetermined level to ensure stable combustion in the new combustion mode.

[0012] Some hybrid electric vehicles (HEVs) have a series configuration, where the motor is electrically connected to the battery and mechanically connected to the engine. Series HEVs also have a second motor, which is also electrically connected to the battery. The drive wheels of a series HEV are mechanically connected to the second motor.

[0013] In other embodiments, the hybrid electric vehicle is configured in parallel, wherein the motor is electrically connected to the battery and mechanically connected to the engine. The motor and the engine are mechanically connected to the drive wheels of the hybrid electric vehicle.

[0014] A hybrid electric vehicle (HEV) is also disclosed, comprising: an electric motor; an internal combustion engine mechanically connected to the electric motor; a battery electrically connected to the electric motor; and a coordination controller (CC) electronically connected to the electric motor, the engine, and the battery. The coordination controller (CC) determines, during a transition interval between a current combustion mode and a new combustion mode, to instruct the engine to transition from the current combustion mode to the new combustion mode, selects one of a plurality of predetermined combustion mode switching operating points for the engine to operate at during the transition interval, and instructs the engine to reach the selected predetermined combustion mode switching operating point during the transition interval. During the transition, if the torque generated by the engine at the selected predetermined combustion mode switching operating point is insufficient, causing the engine speed to decrease, the electric motor acts as a motor and drives the engine to prevent its speed from decreasing, thereby maintaining the engine operating at the selected predetermined combustion mode switching operating point. During the transition, if the torque generated by the engine at the selected predetermined combustion mode switching operating point is excessive, causing the engine speed to increase, the electric motor acts as a generator and loads the engine, thereby maintaining the engine operating at the selected predetermined combustion mode switching operating point.

[0015] The selected combustion mode switching point is based on at least one of the following: the battery's state of charge and the vehicle driver's torque demand on the vehicle's drive wheels.

[0016] During the transition interval, the engine prepares for operation in the new combustion mode. This preparation involves at least one of the following: adjusting the engine intake system temperature, adjusting the engine intake system pressure, changing the proportion of exhaust gas introduced into the engine intake system, changing the engine compression ratio, changing the air-fuel ratio entering the engine, changing the engine fuel injection timing and injection quantity, changing the engine ignition timing, and changing the engine valve timing. The Coordinating Controller (CC) instructs the engine to operate in the new combustion mode after completing this preparation.

[0017] The decision to instruct the engine to transition from the current combustion mode to the new combustion mode is based on the fact that the hybrid electric vehicle operates more efficiently in the new combustion mode than in the current combustion mode.

[0018] Determining whether to instruct the engine to transition from the current combustion mode to a new combustion mode is further based on at least one of the following: the vehicle driver's torque demand, sufficient engine preheating, or in some embodiments, sufficient engine cooling, and in other embodiments, the ability to support stable combustion in the new combustion mode, and the battery's state of charge.

[0019] In some embodiments, the hybrid electric vehicle is a series configuration, wherein the motor is a first motor, and both the first and second motors are electrically connected to the battery. The first motor is mechanically connected to the engine. The drive wheels of the series hybrid electric vehicle are mechanically connected to the second motor.

[0020] In other embodiments, the hybrid electric vehicle (HEV) is in parallel configuration, wherein the electric motor is mechanically connected to the engine. The electric motor and the engine are mechanically connected to the drive wheels of the hybrid electric vehicle (HEV).

[0021] A method for controlling a series hybrid electric vehicle (HEV) is also disclosed. The vehicle includes a first motor (EM1) mechanically connected to an engine (ICE), a second motor (EM2) mechanically connected to the drive wheels of the HEV, and a battery electrically connected to the first motor (EM1) and the second motor (EM2). The method includes: determining to instruct the engine to transition from the current combustion mode to the new combustion mode during a transition interval between a current combustion mode and a new combustion mode; selecting an operating point from a plurality of predetermined combustion mode switching operating points for the engine to operate at during the transition interval; instructing the engine to reach the selected predetermined combustion mode switching operating point during the transition interval; and instructing the engine to operate in the new combustion mode after the transition interval.

[0022] During the transition interval, the engine prepares to operate in the new combustion mode. This preparation includes at least one of the following: adjusting the engine intake system temperature, adjusting the engine intake system pressure, changing the proportion of exhaust gas introduced into the engine intake system, changing the engine compression ratio, changing the air-fuel ratio entering the engine, changing the engine fuel supply strategy including fuel injection time and injection quantity, and changing the valve timing and valve lift of the engine valves.

[0023] When the engine produces insufficient torque at the selected predetermined combustion mode switching operating point, causing the engine speed to drop, the first motor (EM1) acts as an electric motor and drives the engine to prevent the speed from dropping, thereby maintaining the engine operating at the selected predetermined combustion mode switching operating point. During the combustion mode transition, the battery provides power to the first motor (EM1) to drive the engine, while simultaneously providing power to the second motor (EM2) to drive the hybrid electric vehicle drive wheels.

[0024] When the engine generates excess torque at a selected predetermined combustion mode switching operating point, causing the engine speed to increase, the first electric motor (EM1) acts as a generator and loads the engine, thereby maintaining the engine's operation at the selected predetermined combustion mode switching operating point. During the combustion mode transition, the battery absorbs the electricity generated by the first electric motor (EM1) loading the engine. The battery and the first electric motor (EM1) supply electricity to the second electric motor (EM2) to drive the hybrid electric vehicle's drive wheels.

[0025] A method for controlling a parallel hybrid electric vehicle (HEV) is also disclosed. The vehicle includes a first motor (EM1) mechanically connected to an internal combustion engine (ICE), the first motor (EM1) and the engine mechanically connected to the drive wheels of the HEV, and a battery electrically connected to the first motor (EM1). The method includes: determining to instruct the engine to transition from the current combustion mode to the new combustion mode during a transition interval between a current combustion mode and a new combustion mode; selecting an operating point from a plurality of predetermined combustion mode switching operating points for the engine to operate during the transition interval; instructing the engine to operate at the selected predetermined combustion mode switching operating point during the transition interval; and instructing the engine to operate in the new combustion mode after the transition interval.

[0026] During the transition interval, the engine prepares to operate in the new combustion mode. This preparation includes at least one of the following: adjusting the engine intake system temperature, adjusting the engine intake system pressure, adjusting the exhaust gas recirculation ratio introduced into the engine intake system, changing the engine compression ratio, changing the air-fuel ratio entering the engine, changing the engine fuel supply strategy including fuel injection time and injection quantity, and changing the valve timing and valve lift of the engine valves.

[0027] When the engine produces insufficient torque at the selected predetermined combustion mode switching operating point, causing the engine speed to drop, the first motor (EM1) acts as an electric motor and drives the engine to prevent the speed from dropping, thereby maintaining the engine operation at the selected predetermined combustion mode switching operating point. During the combustion mode transition, when the first motor (EM1) acts as an electric motor, the battery provides power to the first motor (EM1) while simultaneously driving the engine and the drive wheels of the hybrid electric vehicle.

[0028] When the engine generates excess torque at a selected predetermined combustion mode switching operating point, causing the engine speed to increase, the first electric motor (EM1) acts as a generator and powers the engine, thereby maintaining the engine's operation at the selected predetermined combustion mode switching operating point. During combustion mode transitions, when the first electric motor (EM1) acts as a generator, the battery absorbs the electricity generated by the first electric motor (EM1) powering the engine. The engine provides torque to drive the first electric motor (EM1) and simultaneously drives the drive wheels of the hybrid electric vehicle. Brief description of the attached figures

[0029] Figure 1a -d shows an example of a series-parallel hybrid electric vehicle in schematic form;

[0030] Figure 2 This is a schematic diagram of a series hybrid electric vehicle;

[0031] Figure 3 This is a schematic diagram of a single-cylinder internal combustion engine;

[0032] Figure 4a -c respectively indicates spark ignition combustion mode; spark-assisted compression ignition combustion mode; and homogeneous charge compression ignition combustion mode;

[0033] Figure 5 Display a flowchart showing the transition from one combustion mode to another;

[0034] Figure 6a -d, 7a, 7b, 8a and 8b show examples of transitioning from the current combustion mode to a new combustion mode according to embodiments of the present disclosure. Detailed Implementation

[0035] Those skilled in the art will understand that various features of the embodiments shown and described with reference to any of the accompanying drawings can be combined with features shown in one or more other drawings to produce alternative embodiments not explicitly shown or described. The combinations of features shown provide representative embodiments for typical applications. However, for a particular application or implementation, various combinations and modifications of features consistent with the teachings of this disclosure may be required. Those skilled in the art will recognize similar applications or implementations, whether explicitly described or illustrated.

[0036] Hybrid electric vehicles began appearing on the market more than two decades ago. These vehicles use a traditional internal combustion engine as their power source. However, their powertrain integrates a battery and an electric motor in addition to a transmission or gear system. The electric motor can operate in generator mode, acting as a generator, where it draws rotational power from the engine or vehicle during regenerative braking to produce electrical energy and stores it in the battery. In other situations, the electric motor operates as a motor to drive the vehicle, partially or completely replacing the engine as the power source for propulsion. The battery is a device that stores the electrical energy generated by the motor or supplies electrical energy to the motor, depending on the operating mode.

[0037] Figure 1a This is a schematic diagram of a series-parallel hybrid electric vehicle, including an engine 12 and two electric motors 22 and 24. The propulsion force provided to the drive wheels 50 can be provided solely by engine 12, or together by engine 12 and motor 22 when clutch 34 is engaged. That is, engine 12, or engine 12 and motor 22, provides torque to one side of clutch 34 via shaft 31. When engaged, the torque is transmitted to shaft 36 connected to transmission 40, and then to the output shaft 42 of transmission 40. Shaft 42 is connected to differential 44, which is connected to half-shaft 46, which then drives drive wheels 50 (parallel hybrid configuration). In this operating mode, the parallel hybrid configuration may not require motor 24. Motor 24 is connected to transmission 40 via shaft 62. When clutch 34 is engaged, motor 24 can also provide torque to drive wheels 50. Alternatively, in another operating mode, clutch 34 disengages and the propulsion torque of drive wheel 50 is provided solely by motor 24, motor 22 loads engine 12 to generate electricity to power motor 24 and charge battery 20 (series hybrid configuration).

[0038] Both motors 22 and 24 are electrically connected to the battery 20 via cable 26. Motor 22 is connected to the engine 12 via shafts 60 and 31, which have gear sets 30. When unloaded, motor 22 simply rotates relative to the engine 12. When loaded, meaning operating in generator mode, motor 22 draws torque from the engine 12 to generate electricity, which is stored in the battery 20. Motor 22 can also act as a motor to start or drive the engine 12, for example, when the engine 12 undergoes a combustion mode transition, when clutch 34 is disengaged. This is called a parallel hybrid electric vehicle because it can be driven by both the engine and the motor together, or by either the motor or the engine individually.

[0039] Besides mechanical hardware Figure 1aThe hybrid electric vehicle also includes various electronic hardware components. An engine electronic control unit (EECU) 74 is electronically connected to the engine 12. The control of the engine 12 will be described in more detail below. A battery controller (BC) 76 is electronically connected to the battery 20. During charging and discharging, the battery controller 76 receives signals from the individual cells of the battery 20 regarding temperature and state of charge, as well as current and voltage. Based on this information, the battery controller determines operating parameters to protect the battery, such as preventing overheating. In some cases, this information is used to limit the discharge or charging rate of the battery 20 or to indicate the state of charge of the battery 20, which affects the operating mode of the hybrid electric vehicle. A first motor controller (EM1C) 78 is electronically connected to the motor 22; a second motor controller (EM2C) 80 is electronically connected to the motor 24. Controllers 78 and 80 control whether their respective motors operate as generators or motors and how much current is supplied to the windings to control the torque level supplied or absorbed by the motors. A transmission controller (TC) 82 is electronically connected to the transmission 40. In many control scenarios, the signals used for controller communication actually communicate with the device drivers to influence the desired control. Such device drivers are well known to those skilled in the art and are not shown separately here for clarity. Of course, controllers 72, 74, 76, 78, 80, and 82 can be individual units or combined into a single controller or multiple controllers with overlapping functions. These controllers are shown as a combination of the Vehicle System Controller (VSC) 90. Furthermore, input 70 is shown as being provided to the Coordination Controller (CC) 72; this description is not intended to be limiting. Input 70 can be directly provided to any controller; and all controllers within the VSC 90 are electronically interconnected, allowing information sharing. The Coordination Controller 72 is also provided because many decisions need to be made, such as the appropriate gear for the transmission 40, depend on other factors, such as engine speed and whether the electric motor 22 is in generator / electric motor mode, and other factors are interrelated. The Coordination Controller 72 communicates with all other controllers. In addition, by way of a few examples only, other inputs 70 are provided to the Coordination Controller, such as temperature, pressure, accelerator pedal position, humidity, and navigation information. Alternatively, input 70 can be directly provided to the relevant controller; for example, humidity may only be relevant to the EECU 74 and can be directly provided to such a controller. Input 70, or it is called a sensor.

[0040] exist Figure 1bAnother hybrid electric vehicle has two sets of drive wheels 150 and 152. Drive wheel 152 is driven solely by motor 124 in electric motor mode, or, when motor 124 operates in generator mode, motor 124 can brake drive wheel 152. Motor 124 is connected to drive wheel 152 via shaft 162, differential 164, and half-shaft 166. Drive wheel 150 is driven by one or both of engine 112 and motor 122. Engine 112 drives drive wheel 150 when clutch 133 and clutch 164 are engaged, connecting shafts 131 and 132. Shaft 132 is connected to transmission 140 via gear set 130 and shaft 160, and shaft 160 is connected to differential 144 via shaft 142. Differential 144 is connected to drive wheel 150 via half-shaft 146. When clutch 133 is engaged, motor 122 is connected to engine 112. A gear set 130 is provided between motor 122 and engine 112 via shafts 160, 131, and 132. Motors 122 and 124 are electrically connected to battery 120 via cable 126. Similar to... Figure 1a , Figure 1b The hybrid electric vehicle in the model includes an engine controller 174, a battery controller 176, electric motor controllers 178 and 180, a transmission controller 182, and a coordination controller 172 with inputs from sensors 170. These controllers are electronically connected directly or indirectly to their respective components, such as the battery controller 176 of the battery 120, via device drivers. Figure 1b This arrangement allows drive wheels 150 and 152 to be driven solely by motors 122 and 124 when clutch 133 is disengaged. When clutch 133 is engaged, motor 122 is passive, meaning no current is supplied to its coils, and drive wheel 150 is driven solely by engine 112. Therefore, when it rotates, it does not drive or load engine 112, except for friction within the system. Furthermore, motors 122 and 124, as well as engine 112, can all be used to drive the vehicle simultaneously. If motor 124 is omitted in this embodiment, a parallel hybrid electric vehicle is formed. In this embodiment, clutch 164 is disengaged, clutch 133 is engaged, and the hybrid electric vehicle is driven solely by motor 124, forming a series hybrid electric vehicle.

[0041] exist Figure 1cThe diagram illustrates another hybrid electric vehicle in which both drive wheels 250 and 252 can be driven. Drive wheel 252 is driven solely by motor 224 in electric motor mode, or, when motor 224 operates in generator mode, motor 224 can brake drive wheel 252. Drive wheel 250 is driven by engine 212 when clutch 233, connecting shafts 232 and 236, is engaged. Shaft 236 is connected to transmission 240, which is connected via shaft 242 to differential 244, which is connected to the half-shafts 246 of drive wheel 250. Motor 222 is connected to engine 212 via belt drive system 260. If belt drive system 260 is a toothed belt, engine 212 can drive motor 222, or motor can drive engine 212. Similar to... Figure 1a In an alternative embodiment, if motor 224 is omitted, the resulting configuration is a pure parallel hybrid electric vehicle. In another embodiment, clutch 233 is disengaged and the hybrid electric vehicle is propelled solely by motor 224, forming a series hybrid electric vehicle.

[0042] Figure 1c The controller situation in the middle is similar to Figure 1a and 1b The controller situation in the middle. Figure 1c The hybrid electric vehicle has an EECU 274, a battery controller 276, motor controllers 278 and 280, a transmission controller 282, and a coordination controller 272 with inputs from sensors 270.

[0043] exist Figure 1d The present invention relates to another type of hybrid electric vehicle with a planetary gear system, wherein an engine 312, an electric motor 322, an electric motor 324, and drive wheels 350 are mechanically connected. Drive wheels 350 can be driven simultaneously or individually by the engine 312 via shaft 331 and the electric motor 324 via shaft 362. In series hybrid mode, in generator mode, the electric motor 322 via shaft 361 can be driven by the engine 312 via shaft 331 to supply power to the electric motor 324 or to charge the battery 320. In parallel hybrid mode, with speed regulation of the electric motor 322 via shaft 361, both the electric motor 324 via shaft 362 and the engine 312 via shaft 331 can drive drive wheels 350 via the planetary gear system. The planetary gear system is connected to wheels 350 via shaft 342, differential 344, and half-shafts 346.

[0044] Figure 1d The controller situation in the middle is similar to Figure 1a The controller information in -c. Figure 1d The hybrid electric vehicle has an engine controller EECU374, a battery controller 376, motor controllers 378 and 380, and a coordination controller 372 with inputs from sensors 370.

[0045] Figure 1a Hybrid electric vehicles in the -d configuration can operate in parallel mode, meaning both the engine and the electric motor can propel the vehicle. Hybrid electric vehicles can also operate in series mode, where the mechanical connection between the engine and the drive wheels is broken via a clutch. Figures 1a-1c As shown, or through a power distribution mechanism and control, the wheels are not driven by the engine, such as Figure 1d As shown.

[0046] In a series configuration, there is no direct mechanical connection between the engine and the vehicle's drive system; sometimes referred to as a range extender, the vehicle is driven solely by the electric motor. This system... Figure 2 As shown, drive wheel 450 is driven solely by motor 424 in electric motor mode. In certain operating modes, such as regenerative braking, motor 424 operates in generator mode. Motor 424 is connected to drive wheel 450 via shaft 442, differential 444, and half-shaft 446. Engine 412 and motor 422 are connected via shafts 431 and 460 and gear set 430, wherein engine 412 drives motor 422 to generate electrical energy to power motor 422 and charge battery 420. Drive wheel 450 is driven solely by motor 424 in electric motor mode; alternatively, when motor 424 operates in generator mode via shaft 436, motor 424 can brake drive wheel 450. Shaft 436 connects motor 424 to gear train 440, gear train 440 is connected to differential 444 via shaft 442. Differential 444 is connected to drive wheel 450 via half-shaft 446. Motors 422 and 424 are electrically connected to battery 420 via cable 426. Figure 1a similar, Figure 2 The hybrid electric vehicle in the device has an engine controller 474, a battery controller 476, electric motor controllers 478 and 480, and a coordination controller 472. These controllers are electronically connected to their respective components, such as the battery 420 and the battery controller 476, directly or indirectly via the device drive. Figure 2 The arrangement allows propulsion to be supplied to the drive wheel 450 solely through the motor 424.

[0047] Figure 1a -d and Figure 2 All electronic controllers are shown as distributed units. However, these controllers can be grouped together. Alternatively, a single controller can be used to manage the functions of two or more controllers distributed as shown, or the functions of one of the distributed controllers can be shared between the two controllers. For the purposes of this application, Figure 1a The processing capabilities shown in -d and 2 can be considered as those of the Vehicle System Controller (VSC). Figure 1a 90 in Figure 1b 190 in the middle, Figure 1c290 in the middle, Figure 1d 390 in the middle, and Figure 2 (490 in the middle).

[0048] VSC consists of multiple controllers that communicate with each other. One of these controllers is the coordinating controller (CC), which coordinates the other controllers.

[0049] Despite Figure 1a -d or Figure 2 This is not stated in any of them. In other embodiments, Figure 1a -d and Figure 2 The functionality of the multiple electronic controllers in the system can be provided by any suitable combination of processing units.

[0050] Those skilled in the art will know that the electronic controller provides signals to the device controller that manages the various components of a hybrid electric vehicle. For example, a signal from the EECU used to control the engine fuel supply is at a certain signal voltage level and is provided to the device driver, which has the electrical capability to issue pulse width commands to the fuel injectors. To those skilled in the art, VSC (Vehicle System Controller) is a coordinated control system composed of multiple controllers that provides signals only to intermediate devices to control components of the hybrid electric vehicle, such as the battery and engine.

[0051] If the battery of the aforementioned hybrid system cannot be charged externally, it is called a hybrid electric vehicle (HEV). If the battery of the aforementioned hybrid system can be charged by an external power source, and the electric motor of the aforementioned hybrid system has sufficient electric power to drive the vehicle, it is called a plug-in hybrid electric vehicle (PHEV). Here, the term HEV refers to both conventional hybrid electric vehicles and plug-in hybrid electric vehicles, as they both rely on an engine and an electric motor; the only difference is the ability to be charged by an external power source and the different battery capacities.

[0052] Vehicles driven by electric motors have significant advantages in responding to the vehicle's driving power demands, such as high output torque at low speeds, smooth speed regulation, fast response time, and high efficiency. Furthermore, electric motors can better meet the driver's random demands for large and rapid changes in output power, depending on road and traffic conditions.

[0053] Currently, (plug-in) hybrid electric vehicles primarily use spark-ignition gasoline engines or compression-ignition diesel engines, along with electric motors / generators and batteries for energy storage and discharge. The engine is tuned to operate at a low fuel consumption point. The electric motor assists the engine in propelling the vehicle's drive wheels, or at other operating points, it acts as a generator to recover energy from the vehicle, such as during deceleration and braking. In urban areas, hybrid electric vehicles can achieve significantly lower fuel consumption than conventional engine vehicles. Some plug-in hybrid electric vehicles (PHEVs) have an all-electric range (AER), meaning that electricity from the grid is used to power the vehicle instead of hydrocarbon fuels, further reducing fuel consumption.

[0054] Figure 3 This illustration shows a single-cylinder engine (ICE) 500. This engine is an alternative to engines 12, 112, 212, 312, and 412 shown in the previous images. Figure 1a -d and Figure 2 The engines in the hybrid electric vehicles mentioned are likely to be multi-cylinder engines. For clarity, Figure 3 The schematic diagram shows only one cylinder of this engine. Engine 500 has an intake passage 530, an exhaust passage 540, and a turbocharger 550. Engine 500 has a cylinder block 510 and a cylinder head 520. Cylinder 511 is located within the cylinder block 510, and piston 502 reciprocates within the cylinder. Combustion chamber 509 is defined by the cylinder head 520, the top of piston 502, and the surface of cylinder 511.

[0055] The cylinder head 520 has an intake port 503 and an exhaust port 504. The intake port 503 supplies intake air to the combustion chamber 509. Exhaust gas is discharged from the combustion chamber 509 through the exhaust port 504. The flow rates into and out of the combustion chamber 509 are controlled by an intake lift valve 505 in the intake port 503 and an exhaust lift valve 506 in the exhaust port 504.

[0056] Cam 575 opens and closes intake valve 505. Similarly, cam 576 opens and closes exhaust valve 506. Cams 575 and 576 are connected to camshafts 577 and 578, respectively. In some embodiments, camshafts 577 and 578 are connected to crankshafts (…). Figure 3 (Not shown) rotates in a fixed relationship. In the variable valve timing embodiment, camshafts 577 and 578 have some limited independent adjustment range relative to the crankshaft, making the cams on the crankshaft adjustable in terms of opening and closing times.

[0057] The cylinder head 520 has a spark plug 507 located in the center. The spark plug 507 may also be located in other positions within the combustion chamber 509.

[0058] exist Figure 3In one embodiment, a turbocharger 550 is provided to pressurize the intake air. In other embodiments contemplated by the inventors of this disclosure, the internal combustion engine may not be turbocharged, omitting the turbocharger 500 and related hardware. The turbocharger 550 includes a compressor 551, a turbine 552, and a shaft 553 connecting the compressor 551 and the turbine 552. Energy in the exhaust is extracted by the turbine 552 located in the exhaust passage 540. The compressor 551 is rotated via the shaft 553, thereby pressurizing the intake air within the intake passage 530. The intake passage 530 also includes an intake filter 531 (for removing unwanted particles or droplets from the intake air that may damage the engine 500), an air flow meter 532 (for measuring the amount of air passing through the air passage 530), a pressure sensor 536, a throttle valve 533 (for controlling the amount of air entering the engine 500), and an intercooler 534 (for cooling the intake air that has been heated by the compressor 551).

[0059] In some applications, the engine 500 requires heating the intake air when operating in a certain combustion mode. An intake air heater 539 is located in the intake passage 530.

[0060] Fuel injector 508 is located in intake passage 530, such as Figure 3 The upper part of the intake duct 503 is shown. In other embodiments, a fuel injector 508 is disposed within the intake duct 503. In both locations, the fuel injector 508 is a relatively low-pressure injector. In still other embodiments, the fuel injector 508 is a high-pressure injector, with its nozzle located within the combustion chamber 509. This configuration is called direct injection. In some embodiments, a fuel injector located within the intake passage 530 and a fuel injector located within the combustion chamber 509 are provided. Such a configuration not only accommodates the use of different fuels with different characteristics but also accommodates the use of different fuel injection strategies for some combustion mode control applications (e.g., SACI).

[0061] A pressure sensor 536 is provided in the intake duct 530 between the throttle valve 533 and the compressor 551 to measure the boost pressure in the intake duct 530. In some embodiments, the pressure sensor is also disposed in the intake duct downstream of the throttle valve 533.

[0062] The catalytic converter 541 is disposed in the exhaust passage 540 downstream of the turbine 552. In other embodiments, other exhaust aftertreatment devices, such as a lean nitrogen oxide trap or a particulate filter, are disposed in the exhaust passage 540 to replace or be attached to the catalytic converter 541.

[0063] In some embodiments, the engine 500 has an intake recirculation passage 560 with an intake recirculation valve 561. The valve 561 opens when the pressure of the air received from the compressor 551 is higher than a desired value.

[0064] Engine 500 has an exhaust gate valve 571 disposed in a bypass passage 570. The bypass connects to an exhaust passage 540 on the upstream and downstream sides of turbine 552. Exhaust gate valve 571 controls the pressure supplied to turbine 552, thereby controlling the speed of turbine 552 of turbocharger 550 to a suitable level.

[0065] Engine 500 also features an Exhaust Gas Recirculation (EGR) system, which includes: an EGR passage 580 connecting exhaust passage 540 (downstream of turbine 552) to intake passage 530 (upstream of compressor 551), an EGR valve 582 for controlling the amount of exhaust gas flowing from the exhaust to the intake, and an EGR cooler 581. EGR uses exhaust gas to dilute the intake air, thereby reducing the combustion temperature in cylinder 509 and thus reducing nitrogen oxide (NOx) formation. EGR also improves engine efficiency by reducing throttling losses. Furthermore, in some combustion modes, exhaust gas dilution of the intake mixture is necessary to control the combustion rate. Too rapid combustion (autoignition) can cause noise and is counterproductive because it occurs at the wrong time in the cycle. Additionally, autoignition can cause overheating of the combustion chamber surfaces, which, if left uncontrolled, can melt the surfaces and damage engine 500.

[0066] The EGR cooler 581 lowers the temperature of the recirculated exhaust gas in the intake air to reduce the amount of NOx produced during combustion, as NOx is very sensitive to temperature.

[0067] Engine 500 includes an engine electronic control unit (EECU) 574: which receives signals from sensors, calculates the desired operating point based on sensor data, and commands actuators associated with the engine to operate. Signals come from: an airflow sensor 532, an intake pressure sensor 536, and other sensors 592. Other sensors include: an engine crankshaft angle sensor to determine engine speed and engine position; an accelerator pedal position sensor to determine the driver's desired driving posture; a brake pedal sensor; a humidity sensor; temperature sensors (engine coolant, air temperature, EGR temperature, etc.); pressure drop sensors (e.g., through air filter 531); pressure sensors; valve position sensors; etc. In autonomous driving mode, the desired engine operating point can be determined by another controller or within EECU 574. EECU 574 can communicate with other controllers, such as a transmission controller, motor controller, and battery controller. In some embodiments, a coordination controller may even be included.

[0068] The appropriate operating point of the engine 500 is determined based on sensor data and other information provided to the EECU 574, such as: fuel injection timing and quantity, spark plug 507 timing, throttle valve 553 position, EGR valve 582 position, exhaust gas valve 571 position, intake air recirculation valve 561 position, intake air heating via heater 539, and the opening / closing time of lift valves 505 and 506.

[0069] The accelerator pedal 594 sends signals to the EECU 574. This EECU 574 is an EECU ( Figure 1a 74 in Figure 1b 174 in Figure 1c 274 and Figure 1d (Referring to 374 in the original text). The accelerator pedal 594 is the way the vehicle driver indicates how they want to drive the vehicle. Alternatively, in an autonomous vehicle, the vehicle is controlled based on the desired route and other inputs, such as traffic and obstacles. In a conventional hybrid electric vehicle, the vehicle driver communicates the desired speed via the accelerator pedal 594. The controller coupled to the accelerator pedal signal translates this request into a desired torque, which in some operating modes can be further translated into a torque request signal for the EECU 574. When the driver releases the accelerator pedal to decelerate, the required torque decreases, and the vehicle decelerates. When the driver presses the accelerator pedal, the required torque increases, and the vehicle accelerates.

[0070] As mentioned above, Engine 500 can operate in multiple combustion modes, some of which significantly reduce fuel consumption compared to the conventional spark ignition (SI) operation mode. Before describing how a hybrid electric vehicle can help facilitate the transition between SI and other combustion modes, alternative combustion modes are discussed below.

[0071] Homogeneous charge compression ignition (HCCI) is a combustion mode that has garnered significant attention. Similar to compression ignition (CI) engines, combustion occurs spontaneously during the compression stroke due to the high temperatures generated by the compressed gas. Furthermore, like CI engines, there is no throttling; the cylinders are fully charged. In SI engines, the amount of air entering the engine is controlled by the throttle valve, resulting in a precise fuel-air ratio in the combustion chamber. By avoiding throttling, HCCI engines offer fuel economy approaching that of CI engines. The timing of combustion initiation is controlled by the time it takes for the mixture temperature to rise to its auto-ignition temperature, which is relatively difficult to control. Because the mixture is premixed and lean, combustion using HCCI produces virtually no soot or NOx.

[0072] HCCI combustion is generally only suitable for low to medium load conditions. This is because combustion becomes harsh and noisy as engine load and fuel concentration increase to a certain level. When the torque demand from the engine exceeds the suitable operating range of HCCI, it will transition to SI or other combustion modes. Furthermore, HCCI is not suitable for cold starts due to the low engine block temperature and significant heat loss through the cold walls. SI combustion is suitable for cold starts, transitioning to HCCI only after the engine has been sufficiently preheated and the required operating point is suitable for HCCI operation.

[0073] Different techniques can be used to control HCCI combustion. One solution, called Controlled Automatic Ignition (CAI), controls the amount of additional exhaust gas in the cylinder by altering the opening and closing times of the intake and exhaust valves under low load conditions. The presence of a large amount of hot residual exhaust gas raises the temperature of the air-fuel mixture in the cylinder, allowing it to reach its auto-ignition temperature and ignite within the appropriate timeframe of the engine's compression stroke.

[0074] Another solution, called Optimized Dynamics Process (OKP), increases the engine's compression ratio to around 15:1. It utilizes the heat from exhaust gas and coolant to heat the intake air, which then enters the cylinder along with the unheated intake air. By controlling the ratio of these two airflows, the intake air temperature can be rapidly adjusted, thereby controlling the combustion time of HCCI (Hydraulic Combustion Process). Bench tests have demonstrated that this approach can significantly reduce fuel consumption, and HCCI has a relatively wide operating range, covering the low-to-medium load conditions commonly used in automotive engines.

[0075] Another type related to HCCI is called Spark-Assisted Compression Ignition (SACI), which allows for operation at higher torque levels than HCCI through spark assistance. The air-fuel mixture is heated to a temperature above the critical temperature for ignition and flame propagation (but still below the auto-ignition temperature), and then ignited by a spark plug. The ignited mixture propagates through the flame, causing more of the mixture to participate in combustion and releasing heat, further increasing the pressure and temperature within the cylinder. The remaining unburned mixture reaches its auto-ignition temperature and spontaneously combusts. This "ignition-induced homogeneous charge compression ignition" combustion mode can be used as a transitional mode between HCCI and SACI.

[0076] To lower the minimum air-fuel mixture temperature required for ignition-induced homogeneous charge compression ignition (HCCC) and to broaden the range of air-fuel mixture temperatures needed for combustion control, the mixture near the spark plug can be locally enriched. For this reason, a small amount of fuel injection can be achieved during the compression cycle in the cylinder.

[0077] In addition, there are other HCCI solutions, such as using variable compression ratios and dual-fuel systems. The ignition timing of an HCCI engine can also be assisted by heating the intake air temperature, which affects the temperature inside the cylinder.

[0078] Although HCCI and SACI combustion modes have shown great potential to significantly reduce fuel consumption and have been tested on fleet vehicles, they have not yet been used in commercial production and sales due to the technical difficulties in controlling combustion.

[0079] Because HCCI control is more complex and challenging, switching from conventional combustion mode to HCCI combustion mode requires a clear understanding and careful prior study of the combustion mode switching strategy and control algorithm to issue appropriate commands to the control unit, allowing the engine control actuators to adjust step by step. However, the engine's operating point and thermal state are virtually unlimited before mode switching. Therefore, the workload of carefully studying all these possible combustion mode switching points in advance is too great, which has become a major obstacle to the application of multi-combustion mode engines in automotive products.

[0080] For the reasons mentioned above, it is necessary to find an effective, reliable, stable and practical engine combustion mode switching strategy and control algorithm to realize the application of multi-combustion mode engines in automotive products.

[0081] refer to Figure 4a -c, compares several combustion modes. Figure 4a SI combustion is now displayed. Combustion chamber 600 has a spark plug 602 that produces a spark core 604. The air-fuel mixture with a higher fuel concentration in combustion chamber 600 is shown as 606 in the illustration. Below combustion chamber 600 is a timeline of events from before bottom dead center (BDC) to at top dead center (TDC) and slightly beyond the compression stroke. Fuel is injected before BDC to provide premixing time, ensuring a substantially homogeneous mixture of fuel and air. The fuel injection duration is shown in box 620. Spark ignition 624 occurs exactly before TDC. SACI combustion is as follows: Figure 4b As shown, the figure illustrates the spark core 604 and two fuel-air mixture regions: a rich region 610 and a lean region 608. A timeline of events is shown below the figure, with some fuel injected at 630 before the burner core (BDC). A small amount of fuel is injected again at 632, near the burner core (TDC). The fuel injected at 630 produces the premixed gas 608, while the fuel injected at 632 produces the rich region 610 near the spark core 604. Figure 4cThis displays HCCI combustion. The mixture in cylinder 600 is very lean (612). HCCI combustion does not involve spark ignition. The timing in the diagram shows the fuel supplied to cylinder 600 before BDC. At certain HCCI operating points, the intake air is heated to make the mixture hot enough to ignite automatically after compression. At other operating points with a suitable HCCI combustion range, less or no intake air heating is required for proper combustion. Although not shown, another option is for the engine to adjust control parameters, such as intake air temperature and compression ratio, by rotating the engine shaft via an electric motor when there is no fuel injection and no spark ignition. In this case, the vehicle would be propelled solely by the electric motor.

[0082] Although this article describes HCCI and SACI combustion, many automakers are researching efficient combustion modes that are related to but slightly different from these combustion modes. The inventors of this disclosure intend to include any combustion mode switching.

[0083] According to this disclosure, a hybrid electric vehicle (HEV) includes at least one electric motor, at least one battery pack, and a multi-combustion mode engine. By integrating the electric motor, engine, and battery and utilizing their inherent characteristics to achieve synergy, and through coordinated control of the electric motor and engine, the engine operating point transitions to a known stable combustion mode switching operating point during the transition period. During the transition, the engine output torque does not need to follow the torque demand from the vehicle driver (who may be the driver or an autonomous controller), because, supported by the battery, if the engine output torque is less than the required torque, the electric motor can compensate for the insufficient engine output torque; or, if the engine output torque is greater than the required torque, the electric motor can absorb the excess torque.

[0084] Determining whether to instruct the engine to transition from the current combustion mode to a new combustion mode is based on at least one of the following: the hybrid electric vehicle operates more efficiently in the new combustion mode than in the current combustion mode; the driver's torque demand; the engine is sufficiently preheated, or in some embodiments, the engine is sufficiently cooled, or in other embodiments, it can support stable combustion in the new combustion mode; and the battery's state of charge. For example, when the engine is cold-started, insufficient heat can lead to unstable combustion, so the engine cannot directly enter HCCI combustion and must wait until it is sufficiently preheated. In another example, humidity has a significant impact on non-spark-induced combustion modes, i.e., auto-ignition. In some extremely high humidity environments, unstable combustion also prevents direct entry into HCCI and SACI combustion.

[0085] When the motor and engine are mechanically connected, through coordinated control of the motor and engine, during the combustion mode switching operation, i.e., the transition, the engine's output torque or power is largely independent of the drive wheel torque. During the transition, under the action of the motor, the engine changes from any current operating point to the combustion mode switching operating point in the same combustion mode as instructed.

[0086] The engine combustion mode switching operating point can be a single engine operating point or a limited number of operating points, composed of engine speed and torque, which are predetermined during system development. Based on different engine operating conditions, a predetermined combustion mode switching operating point can be selected. By moving the engine from any current operating point to the selected predetermined combustion mode switching operating point, the engine will follow a predetermined engine combustion mode switching transition control strategy during the transition interval to prepare for operation in the new combustion mode.

[0087] The preparation work required for the engine to switch from the current combustion mode to the new combustion mode includes at least one of the following engine adjustments or controls: engine intake air temperature, engine intake system pressure, proportion of exhaust gas introduced into the engine intake system, engine compression ratio, air-fuel ratio entering the engine, and engine fuel supply strategy including engine fuel injection time and injection quantity, engine ignition timing, and changes in engine valve timing and lift.

[0088] When the torque generated by the engine at the selected predetermined combustion mode switching point is insufficient, causing the engine speed to drop, the electric motor acts as an electric motor and drives the engine to prevent the speed from dropping, thereby keeping the engine running at the selected predetermined combustion mode switching point.

[0089] When the engine generates excess torque at the selected predetermined combustion mode switching point, causing the engine speed to increase, the electric motor acts as a generator and loads the engine, thereby keeping the engine running at the selected predetermined combustion mode switching point.

[0090] After the engine follows the combustion mode switching transition control strategy and completes the preparation work, and its operation meets the new combustion mode switching conditions, the engine operates in the new combustion mode as instructed.

[0091] The engine operates within a new combustion mode range. Under this new combustion mode, the engine's operating point can be controlled at any target operating point as needed.

[0092] During the transition between combustion modes, the engine may operate abnormally, such as fluctuations in the work done by the gas in the cylinder. This can lead to instability, fluctuations, or even interruptions in the engine's output power, including its speed and torque. However, when the motor and engine are mechanically connected, through coordinated control of the motor and engine, the motor and battery can absorb, compensate for, and suppress these fluctuations or even interruptions, thereby maintaining the required operating point for the combustion mode transition, i.e., the engine speed and torque. Therefore, this invention not only ensures a smooth transition between combustion modes but also guarantees that the total output power or net torque of the engine, the motor, and any additional motors connected to the vehicle's drive wheels meets the vehicle's drive power or torque requirements.

[0093] Furthermore, this engine can be controlled within a certain efficient and stable operating range or at a limited operating point, thereby avoiding some operating areas or critical points where combustion and emissions control are difficult. For example, when the engine's operating point in HCCI combustion mode is close to the upper or lower critical point of its operating range, such as... Figure 6b As shown in the overlapping region 664 of SACI and HCCI, combustion control and emission aftertreatment become difficult.

[0094] Since the number of predetermined combustion mode switching points is limited, selecting one or a limited number of engine operating points becomes possible. This necessitates careful optimization of the combustion mode switching strategy and control algorithm for at least one operating point during system development. For example, this includes handling slight deviations in the engine's combustion mode switching point or thermal conditions during the switching process. This includes, but is not limited to, developing multiple sets of control commands to selectively adjust the sequence of the engine's control devices or actuators. After completing the combustion mode switching operation, the engine will operate in the new combustion mode.

[0095] Now for reference Figure 5 The flowchart illustrates the transition from one combustion mode to another. This process begins at 750 rpm and preheats in the first combustion mode, which in a gasoline engine is likely the conventional spark ignition (SI) mode, such as... Figure 4aAs shown. Once the engine is preheated, control is transferred to block 754, where it is determined whether the required torque for the new combustion mode is needed. If not, control returns to block 754 to continue waiting until a combustion mode transition is required or recommended. If required, control moves to block 756, where instructions are given to operate at the selected predetermined combustion mode switching point: the engine and a first motor are mechanically connected, and the first motor coordinates the control of the engine to the selected predetermined combustion mode switching point. The selected predetermined combustion mode switching point is an operating point that allows the engine to prepare for operation in the desired new combustion mode, including adjustments to the engine controls and operating parameters during the transition interval. To reach the selected predetermined combustion mode switching point, the engine may not be able to provide the required torque.

[0096] Control is passed to block 766: If the torque provided by the engine is greater than the demand, then the first motor acts as a generator and powers the engine. If the torque provided by the engine is less than the demand, then the first motor acts as a motor and drives the engine. If the engine does not provide torque (fuel supply cut off), the first motor drives the engine to a selected predetermined combustion mode switching point, where the engine reaches a predetermined speed (rpm) but the torque is zero. For parallel hybrid systems, the engine and the first motor jointly drive the vehicle, with the first motor compensating for and absorbing the difference between the engine's output torque and the vehicle's required torque. For series hybrid systems, the battery and the first motor jointly provide power to the second motor to drive the vehicle, with the battery providing and absorbing the difference between the first motor's output power and the second motor's required power (the vehicle's demand).

[0097] When the engine is running stably at the selected predetermined combustion mode switching operating point, control is transmitted to block 760. To meet the desired operating conditions of the new combustion mode, the engine prepares for operation in the desired new combustion mode by adjusting the engine control device and operating parameters. This preparation includes at least one adjustment: the engine intake system temperature, the engine intake system pressure, the proportion of exhaust gas introduced into the engine intake system, the engine compression ratio, the air-fuel ratio entering the engine, and the fuel supply strategy including changes to the engine fuel injection time and injection quantity, engine ignition timing, and changes to engine valve timing and valve lift.

[0098] Once preparation is complete, control is transferred to block 762, where it is determined whether the engine is ready to switch to the new combustion mode. If not, control returns to block 760 to continue preparation until the conditions for switching combustion modes are met. If so, control moves to block 764, where the engine is instructed to operate in the new combustion mode.

[0099] While the engine is running at block 764, control proceeds to block 754 to determine if the required engine torque necessitates a new combustion mode. If not, the engine will remain at block 764, continuing to operate in the current combustion mode. If necessary, control moves to block 756.

[0100] The transition interval can be a very short few cycles. For example, in some combustion mode switching, the pressure in the intake manifold must increase, requiring the engine to rotate several times. In another example, during the transition to HCCI combustion, the intake manifold is heated by resistance heating or other heating methods, which may take a few seconds. Control moves from block 760 to block 762, where it is determined whether the necessary changes to the engine parameters supporting combustion in the new combustion mode have been made. That is, is the engine ready to stably switch to the new combustion mode? If not, control moves back to block 760 to continue in the transition mode. This cycle continues until the engine parameters, such as intake air temperature, effective compression ratio, intake pressure, and exhaust gas recirculation, which are essential for stable combustion in the new combustion mode, are reached. Then, control moves to block 764 and instructs the engine to change to the new combustion mode. Control returns to block 754 to wait for a change in torque, i.e., whether another transition is needed. Again, if there is no indication that a transition should occur, control will remain in the current combustion mode until a need is found in block 754.

[0101] exist Figure 6a In the diagram, the operating range of a typical SI engine is shown on a graph of engine torque 646 rpm versus engine speed 648 rpm. The maximum torque the engine can produce can be shown as a function of engine speed as curve 650. SI combustion can be implemented within the operating range of curve 650, between the lowest engine speed 652 rpm and the highest engine speed 654 rpm. However, as mentioned earlier, it is desirable to operate in a combustion mode with higher fuel efficiency where possible. Figure 6b In the SI range (surrounded by lines 648, 650, 652, and 654) and exhibiting low torque levels (displayed within the dashed line 660), HCCI is indicated. SACI, exhibiting medium torque levels (displayed within the dashed line 662), is indicated. Within region 660, either HCCI or SI can be operated. Within region 662, either SACI or SI can be operated. Within region 664, which overlaps with HCCI and SACI operation, any of the SI, HCCI, and SACI operations can be employed.

[0102] exist Figure 6cThe diagram shows operating point P1, located below the peak torque curve in the graph, where SI operation is the only option. If lower torque is needed, such as at point P2, SI combustion mode can be used, but operating at this point with the high-efficiency HCCI is also acceptable. To utilize the high-efficiency HCCI, a transition to HCCI is implemented. To operate with HCCI, the throttle is fully open, whereas at point P1 in SI combustion mode, the throttle is partially closed. This helps HCCI heat the intake air for stable ignition. Heating the intake air is a slow process, taking approximately a few seconds, unlike changing the intake pressure, which can be done within a few engine revolutions. Instead of transitioning directly from point P1 to P2, the transition occurs first at an intermediate operating point T1 between P1 and P2. Therefore, the transition is from P1 to T1 and then to P2. Figure 6c The diagram shows line R1. As mentioned above, the engine uses a predetermined operating point during the transition interval between operating points P1 and P2. Note that the engine speed increases while the torque decreases from P1 to P2. An example scenario for this is when a vehicle starts from a traffic light, requiring high torque to accelerate. After the vehicle has almost reached the desired speed, the driver releases the accelerator pedal to slow down acceleration and continues to increase speed slightly, but since the vehicle has essentially reached its speed, less torque is needed. R1 is the speed range from which the predetermined operating point can be selected. Of course, within the range of R1, T1 and P2 can be selected with the same engine speed to meet the driver's needs.

[0103] Figure 6d The combustion mode transitions are shown on a torque versus time graph. There are three intervals: the time the engine operates in the first combustion mode, i.e., at P1, ... Figure 6d The interval is shown as 674. When the desired change in torque occurs, the engine enters transition interval 676. When the engine parameters are suitable for completing the transition, the engine is instructed to operate in the new combustion mode (P2) at interval 678. The dotted line 672 represents the engine's output torque as a function of time. The torque decreases from interval 674 to 676 and then decreases again at 678. The dashed line 670 represents the desired engine torque. At interval 676, the engine torque exceeds the desired torque. This is a case where the electric motor acts as a generator and loads the engine, so the net torque supplied to the drive wheels is the required torque for the parallel hybrid vehicle. For some parallel hybrid electric vehicle configurations as shown in Figure 1, the second motor is connected to the vehicle's drive wheels ( Figure 1a 24 in the middle, Figure 1b 124 in the middle, Figure 1c 224 and Figure 1d(324 in the text), the second motor torque supplements the engine torque to propel the vehicle. Excess torque is shown as 680, which is the difference between curves 670 and 672 in interval 676. The battery absorbs excess power from the motor and, based on the second motor's operating mode, either absorbs or supplies power to or from the second motor. For series hybrid electric vehicles such as... Figure 2 As shown, during the transition between combustion modes, the excess torque of the engine causes the motor 422 to provide excess power, and the battery will absorb the excess power from the motor 422 and provide power to the motor 424 to propel the vehicle separately.

[0104] Figure 7a Engine diagram and Figure 6a and 6b The same as shown. However, during the transition, Figure 7a The content shown is consistent with Figure 6c The content shown is different. That is, the engine starts at point P3 and operates in HCCI combustion mode. The vehicle driver demands a sudden surge of torque, for example, during overtaking maneuvers or climbing hills. The new desired operating point is shown as operating point P4, in the SI combustion mode region. If operating in HCCI, the intake manifold may be heated, and due to engine knock and reduced volumetric efficiency caused by intake heating, the engine cannot immediately transition to point P4. To allow time for the engine parameters to adapt to point P4, the engine is instructed to operate in SACI combustion mode. Figure 7a This is marked as T3. Similarly, this happens to be one of the predetermined torque operating points indicated by R1, which occurs within the engine speed range.

[0105] Figure 7b The diagram shows the engine torque as a function of time. The desired torque is represented by the dashed curve 681, while the torque provided by the engine is shown as the dotted-dash curve 682. During P3, i.e., the first interval 684, the engine torque 682 matches the desired torque 681, where the engine operates in the current combustion mode, in this case, HCCI. In the third interval, 688, when the engine operates in a new combustion mode, the engine torque 682 and the desired torque 681 are again almost equal. During the second interval 686, when the engine operates at T3, i.e., the transition operating point, the engine torque 682 is lower than the desired torque 681. During the second interval 686, the electric motor (EM) acts as the electric motor and drives the engine while providing the insufficient torque, represented by 690, so the net torque provided to the vehicle's drive wheels is equal to the desired torque of the parallel hybrid electric vehicle. Some parallel hybrid electric vehicle configurations are shown in Figure 1, where the second motor is connected to the vehicle's drive wheels (…). Figure 1a 24 in the middle, Figure 1b 124 in the middle, Figure 1c 224 and Figure 1dIn the second motor (324), the torque of the second motor supplements the torque of the engine and propels the vehicle. The insufficient torque is represented by 690, which is the difference between curves 681 and 682 during interval 686. The battery provides power to the electric motor (EM). The battery supplies or absorbs electrical energy from the second motor depending on its operating mode. Series hybrid electric vehicles, such as... Figure 2 As shown, during the transition between combustion modes, due to insufficient engine torque, motor 422 acts as an electric motor, the battery provides power to motor 422 to drive the engine, and provides power to motor 424 to propel the vehicle independently.

[0106] Now for reference Figure 8a The engine diagram shown. Similarly, the description in the diagram is... Figure 6a and 6b The diagrams are similar, but show different transitions in the engine's operating diagram. Starting from point P5 in the current combustion mode, the goal is to move to point P6 in another combustion mode. In this example, the engine is shut down during the transition, T5. Figure 8b In the transition timeline, the engine operates at point P5 during interval 694, the first interval. The torque produced by the engine is shown as the dotted curve 692, and the desired torque is shown as the dashed curve 691. During transition interval 696, the engine produces no torque. During the combustion mode switching transition, in order to provide the desired torque, the parallel hybrid electric vehicle's motor acts as an electric motor to drive the engine to the predetermined combustion mode switching speed (rpm), and simultaneously provides torque 699 to propel the vehicle. Some parallel hybrid electric vehicle configurations are shown in Figure 1, where the second motor is connected to the vehicle's drive wheels (…). Figure 1a 24 in the middle, Figure 1b 124 in the middle, Figure 1c 224 and Figure 1d (324 in the text), the second motor torque supplements the engine torque and propels the vehicle. The torque magnitude is displayed as 699, which is the difference between curves 691 and 692 during the interval 696. The battery provides power to the electric motor (EM). The battery supplies or absorbs electrical energy from the second motor depending on its operating mode. Series hybrid electric vehicles, such as... Figure 2 As shown, during the combustion mode switching transition, since motor 422 does not provide power to motor 424, battery 420 provides power to motor 422 and drives the engine to the selected predetermined combustion mode switching speed (rpm), while simultaneously providing power to motor 424 to propel the vehicle independently. When the engine is ready to enter the new combustion mode, it is displayed as P6, the transition is complete, and the engine torque 692 equals the desired torque 691.

[0107] exist Figure 6dIn 7b and 8a, the duration of the transitions appears to be the same in time. However, this is only for illustrative purposes. Some transitions are very short, a few turns. Other transitions require longer times.

[0108] Although the optimal configuration has been described in detail with reference to embodiments, those skilled in the art will recognize various alternative designs and embodiments within the scope of the appended claims. While various embodiments may have been described as providing advantages or superiority over other embodiments in one or more desired characteristics, as those skilled in the art will know, one or more characteristics may be compromised to achieve desired system properties, depending on the specific application and implementation. These properties include, but are not limited to: cost, efficiency, strength, durability, lifecycle cost, merchantability, speed, range, appearance, packaging, size, maintainability, weight, manufacturability, ease of assembly, etc. The embodiments described herein are characterized as inferior to other embodiments or prior art implementations in one or more features, which are outside the scope of this disclosure and may be desirable for a particular application.

Claims

1. A method for controlling a hybrid electric vehicle, said hybrid electric vehicle having an electric machine, an internal combustion engine and a battery. The motor and the engine are mechanically connected, and the battery is electrically connected to the motor. The method includes: The instruction determines that during the transition interval between the current combustion mode and the new combustion mode, a transition mode is provided during the transition interval, the transition mode being different from the current combustion mode and the new combustion mode; Based on engine operating conditions, during the transition interval, an operating point is selected from a plurality of predetermined combustion mode switching operating points for engine operation. The selected operating point is located between the operating point of the current combustion mode and the operating point of the new combustion mode. The mode switching operating points are a finite number of engine operating points, composed of engine speed and torque, and are predetermined during system development. During the transition interval, the engine is instructed to reach a selected predetermined combustion mode switching operating point, wherein: When the torque generated by the engine at the selected predetermined combustion mode switching operating point is insufficient, causing the engine speed to decrease, the electric motor acts as a motor and drives the engine, thereby maintaining the engine operating at the selected predetermined combustion mode switching operating point; and When the engine generates excessive torque at the selected predetermined combustion mode switching point, causing the engine speed to increase, the electric motor acts as a generator and loads the engine, thereby maintaining the engine at the selected predetermined combustion mode switching point. Once the engine has been operating at the selected predetermined combustion mode switching point, the engine prepares to operate in the new combustion mode during the transition interval. After the engine completes the preparation work, it will operate in the new combustion mode.

2. The method according to claim 1, wherein: The preparation work involves at least one of the following adjustments: the engine intake system temperature, the engine intake system pressure, the proportion of exhaust gas introduced into the engine intake system, the engine compression ratio, the air-fuel ratio entering the engine, the engine fuel supply strategy including fuel injection time and injection quantity, the engine ignition timing, and changes to the engine valve timing and valve lift.

3. The method of claim 1, wherein determining the transition of the engine from the current combustion mode to the new combustion mode is based on at least one of: The charging state of the battery; The engine operating point supports stable combustion under the new combustion mode; The vehicle driver's torque demand on the hybrid electric vehicle and the expected duration of the transition interval; and The hybrid electric vehicle operates more efficiently in the new combustion mode than it does in the current combustion mode.

4. The method according to claim 1, wherein: The hybrid electric vehicle is in a series configuration; The motor is a first motor that is mechanically connected to the engine and electrically connected to the battery; The series hybrid electric vehicle further includes: A second motor is electrically connected to the battery; and The drive wheel is mechanically connected to the second motor.

5. The method according to claim 1, wherein: The hybrid electric vehicle is configured in parallel. The motor is a first motor and is electrically connected to the battery; and During the transition interval, the motor is mechanically connected to the engine, and the motor and the engine are mechanically connected to the drive wheels of the parallel hybrid electric vehicle.

6. A hybrid electric vehicle, comprising: Electric motor; An internal combustion engine is mechanically connected to the electric motor; The battery is electrically connected to the motor; and A vehicle system controller consists of multiple controllers that communicate with each other, one of which is a coordinating controller that coordinates the other controllers among the multiple controllers; The coordination controller determines a command to transition from the current combustion mode to the new combustion mode during the transition interval between the current combustion mode and the new combustion mode, during which there is a transition mode that is different from the current combustion mode and the new combustion mode. Based on engine operating conditions, the coordination controller selects one operating point from a plurality of predetermined combustion mode switching operating points for engine operation during the transition interval. The selected operating point is located between the operating point of the current combustion mode and the operating point of the new combustion mode. The mode switching operating point is a finite number of engine operating points and is composed of engine speed and torque. The mode switching operating point is predetermined in advance during system development. During the transition interval, the coordination controller instructs the engine to reach the selected predetermined combustion mode switching operating point; During the transition interval, if the engine speed drops due to insufficient torque generated at the selected predetermined combustion mode switching operating point, the electric motor acts as an electric motor and drives the engine to prevent the speed from dropping, thereby maintaining the engine operation at the selected predetermined combustion mode switching operating point. and During the transition interval, when the engine generates excess torque at the selected predetermined combustion mode switching operating point, causing the engine speed to increase, the electric motor acts as a generator and loads the engine, thereby maintaining the engine operating at the selected predetermined combustion mode switching operating point. Once the engine has been operating at the selected predetermined combustion mode switching point, the engine prepares to operate in the new combustion mode during the transition interval. After the engine completes the preparation work, it will operate in the new combustion mode.

7. The hybrid electric vehicle according to claim 6, wherein: The coordination controller is electronically connected to the motor controller, the engine controller, and the battery controller.

8. The hybrid electric vehicle according to claim 6, wherein the selection of the predetermined combustion mode switching operating point is based on at least one of: the state of charge of the battery, the driver's torque demand on the drive wheels, the engine's operating point in the new combustion mode supporting stable combustion, and the hybrid electric vehicle operating in the new combustion mode having higher efficiency than the hybrid electric vehicle operating in the current combustion mode.

9. The hybrid electric vehicle according to claim 6, wherein: The preparation work involves at least one of the following adjustments: the engine intake system temperature, the engine intake system pressure, the proportion of exhaust gas introduced into the engine intake system, the engine compression ratio, the air-fuel ratio entering the engine, the engine fuel supply strategy including fuel injection time and injection quantity, the engine ignition timing, and changes to the engine valve timing and valve lift.

10. The hybrid electric vehicle of claim 6, wherein the determination of the command to transition from the current combustion mode to the new combustion mode is based on at least one of the following: the operating efficiency of the hybrid electric vehicle in the new combustion mode is higher than that in the current combustion mode, the driver's torque demand, the new combustion mode supporting stable combustion, and the state of charge of the battery.

11. The hybrid electric vehicle according to claim 6, wherein: The hybrid electric vehicle is in a series configuration; and The motor is a first motor mechanically connected to the engine and electrically connected to the battery, and the series hybrid electric vehicle further includes: The second motor is electrically connected to the battery; and The drive wheel is mechanically connected to the second motor.

12. The hybrid electric vehicle according to claim 6, wherein: The hybrid electric vehicle is configured in parallel. The motor is a first motor and is electrically connected to the battery; and During the transition interval, the motor is mechanically connected to the engine, and both the motor and the engine are mechanically connected to the drive wheels of the parallel hybrid electric vehicle.

13. A method for controlling a series hybrid electric vehicle, the series hybrid electric vehicle having a first motor mechanically connected to an internal combustion engine, a second motor mechanically connected to the drive wheels of the series hybrid electric vehicle, a battery electrically connected to the first and second motors, a second motor controller electronically connected to the second motor, and a coordination controller electronically connected to the second motor controller, the method comprising: The instruction determines that during the transition interval between the current combustion mode and the new combustion mode, a transition mode is provided during the transition interval, the transition mode being different from the current combustion mode and the new combustion mode; Based on engine operating conditions, during the transition interval, an operating point is selected from a plurality of predetermined combustion mode switching operating points for engine operation. The selected operating point is located between the operating point of the current combustion mode and the operating point of the new combustion mode. The mode switching operating point is a finite number of engine operating points and is composed of engine speed and torque. The mode switching operating point is predetermined in advance during system development. During the transition interval, the engine is instructed to reach the selected predetermined combustion mode switching operating point; When the engine's torque is insufficient at the selected predetermined combustion mode switching point, causing a drop in engine speed, the first motor acts as a motor and drives the engine to prevent the speed from dropping, thereby maintaining the engine's operation at the selected predetermined combustion mode switching point; and When the engine generates excessive torque at a selected predetermined combustion mode switching point, causing the engine speed to increase, the first motor acts as a generator and loads the engine, thereby maintaining the engine's operation at the selected predetermined combustion mode switching point; and Once the engine has been operating at the selected predetermined combustion mode switching point, the engine prepares to operate in the new combustion mode during the transition interval. After preparations are completed during the transition interval, the engine is instructed to operate in the new combustion mode.

14. The method of claim 13, wherein: The preparation work includes at least one of the following adjustments: the engine intake system temperature, the engine intake system pressure, the proportion of exhaust gas introduced into the engine intake system, the engine compression ratio, the air-fuel ratio entering the engine, the engine fuel supply strategy including fuel injection time and injection quantity, the engine ignition timing, and changes to the engine valve timing and valve lift.

15. The method according to claim 13, wherein: During the combustion mode transition interval, the battery provides power to the first motor to drive the engine, and at the same time provides power to the second motor to drive the drive wheels of the series hybrid electric vehicle; During the transition interval of the combustion mode, the output power generated by the first motor due to loading the engine is absorbed by the battery and provided to the second motor to drive the drive wheels of the series hybrid electric vehicle.

16. The method of claim 13, wherein determining whether to instruct a transition from the current combustion mode to a new combustion mode is based on at least one of: the series hybrid electric vehicle operating efficiency in the new combustion mode is higher than the operating efficiency of the series hybrid electric vehicle in the current combustion mode, the driver's torque demand, the engine operating point supporting stable combustion in the new combustion mode, and the state of charge of the battery.

17. A method for controlling a parallel hybrid electric vehicle, the parallel hybrid electric vehicle having an electric motor and mechanically connected to an internal combustion engine, the electric motor and the engine being mechanically connected to drive wheels of the parallel hybrid electric vehicle, and a battery being electrically connected to the electric motor, the method comprising: The instruction determines that during the transition interval between the current combustion mode and the new combustion mode, a transition mode is provided during the transition interval, the transition mode being different from the current combustion mode and the new combustion mode; Based on engine operating conditions, during the transition interval, an operating point is selected from a plurality of predetermined combustion mode switching operating points for engine operation. The selected operating point is located between the operating point of the current combustion mode and the operating point of the new combustion mode. The mode switching operating point is a finite number of engine operating points and is composed of engine speed and torque. The mode switching operating point is predetermined in advance during system development. During the transition interval, the engine is instructed to reach the selected predetermined combustion mode switching operating point; During the combustion mode transition interval, when the engine's torque is insufficient at the selected predetermined combustion mode switching operating point, causing the engine speed to drop, the electric motor acts as a motor and drives the engine to prevent the speed from dropping, thereby maintaining the engine's operation at the selected predetermined combustion mode switching operating point. The battery provides power to the electric motor, which drives not only the engine but also the drive wheels of the parallel hybrid electric vehicle. and During the selected predetermined combustion mode switching transition interval, when the engine generates excess torque at the selected predetermined combustion mode switching operating point, causing the engine speed to increase, the electric motor acts as a generator and loads the engine, thereby maintaining the engine operating at the selected predetermined combustion mode switching operating point. The output power generated by the electric motor due to loading the engine is absorbed by the battery, and the engine provides torque to drive the drive wheels of the parallel hybrid electric vehicle. and Once the engine has been operating at the selected predetermined combustion mode switching point, the engine prepares to operate in the new combustion mode during the transition interval. After the transition interval, the engine is instructed to operate in a new combustion mode.

18. The method of claim 17, wherein: The preparation work includes at least one of the following adjustments: engine intake system temperature, engine intake system pressure, proportion of exhaust gas introduced into the engine intake system, engine compression ratio, air-fuel ratio entering the engine, engine fuel supply strategy including fuel injection time and injection quantity, engine ignition timing, engine valve timing and valve lift profile.

19. The method of claim 17, wherein determining whether to instruct a transition from the current combustion mode to a new combustion mode is based on at least one of: the parallel hybrid electric vehicle operating efficiency in the new combustion mode is higher than the parallel hybrid electric vehicle operating efficiency in the current combustion mode, the driver's torque demand, the engine operating point supporting stable combustion in the new combustion mode, and the state of charge of the battery.

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