Hybrid vehicles and emission reduction strategies

Abstract

The present disclosure relates to hybrid vehicles and emission reduction strategies. A vehicle includes a powertrain and a controller. The powertrain has an engine and an electric motor. The controller is configured to maintain steady-state engine torque output and adjust electric motor torque output to meet driver demand as long as the catalytic converter temperature is below a threshold. The controller is further configured to allow adjustment of the engine torque output to meet driver demand in response to the catalytic converter temperature exceeding the threshold.

Description

Technical Field

[0001] The present disclosure relates to a control system for a hybrid vehicle. Background Art

[0002] Conventional strategies for reducing emissions from internal combustion engine powered vehicles after a cold start include adjusting spark timing in the engine, adjusting the air / fuel ratio, and / or adjusting the idle mode to minimize hydrocarbon feed gases while also minimizing catalyst light-off time in the catalytic converter. Summary of the Invention

[0003] A vehicle includes a powertrain and a controller. The powertrain has an engine and an electric motor. The controller is configured to maintain steady-state engine torque output and adjust electric motor torque output to meet driver demand as long as a catalytic converter temperature is below a threshold. The controller is further configured to allow adjustment of the engine torque output to meet driver demand in response to the catalytic converter temperature exceeding the threshold.

[0004] A vehicle includes an engine, an electric motor, an engine exhaust system, and a controller. The engine and the electric motor are each configured to generate torque to propel the vehicle. The engine exhaust system has a catalytic converter configured to operate above a threshold temperature. The controller is configured to maintain a steady-state engine torque output and adjust the electric motor torque output to meet a driver demand torque as long as the temperature of the catalytic converter is less than the threshold temperature. The controller is further configured to, in response to a desired electric motor torque output being outside an operating range of the electric motor to meet the driver demand during the period of maintaining the steady-state engine torque output, adjust the electric motor torque output to a limit of the operating range and override the maintained steady-state engine torque output to adjust the engine torque output to meet the driver demand.

[0005] According to an embodiment of the present invention, the threshold value is the catalytic converter light-off temperature.

[0006] A method for controlling a vehicle powertrain includes maintaining a predetermined steady-state engine torque and adjusting an electric motor torque to meet a powertrain torque demand as long as a catalytic converter temperature is below a threshold. The method also includes adjusting the engine torque and the electric motor torque to meet the powertrain torque demand in response to the catalytic converter temperature exceeding the threshold.

[0007] According to an embodiment of the present invention, the threshold value is the catalytic converter light-off temperature.

[0008] According to an embodiment of the present invention, the threshold value is a predetermined temperature value greater than a light-off temperature of the catalytic converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a schematic diagram of a representative powertrain of a hybrid electric vehicle;

[0010] Figure 2 is a flow chart illustrating a method of controlling a vehicle powertrain according to an emissions reduction strategy after a cold start. DETAILED DESCRIPTION

[0011] Embodiments of the present disclosure are described herein. However, it should be understood that the disclosed embodiments are merely examples, and other embodiments may take various forms and alternative forms. The figures are not necessarily drawn to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, the specific structural and functional details disclosed herein should not be interpreted as limiting, but merely as a representative basis for teaching those skilled in the art to utilize the described embodiments in various forms. As will be understood by those of ordinary skill in the art, the various features shown and described with reference to any one of the figures may be combined with features shown in one or more other figures to produce embodiments that are not explicitly shown or described. The combinations of features shown provide representative embodiments for typical applications. However, various combinations and variations of features consistent with the teachings of the present disclosure may be desired for specific applications or implementations.

[0012] Reference Figure 1 , a schematic diagram of a hybrid electric vehicle (HEV) 10 is shown according to an embodiment of the present disclosure. Figure 1 Representative relationships between components are shown. The physical arrangement and orientation of the components in the vehicle may vary. The HEV 10 includes a powertrain 12. The powertrain 12 includes an engine 14 that drives a transmission 16, which may be referred to as a modular hybrid transmission (MHT). As will be described in further detail below, the transmission 16 includes an electric machine (such as an electric motor / generator (M / G) 18), an associated traction battery 20, a torque converter 22, and a multi-step ratio automatic transmission or gearbox 24.

[0013] Both the engine 14 and the motor / gear 18 are drive sources for the HEV 10 and are configured to propel the HEV 10. The engine 14 generally represents a power source that may include an internal combustion engine (such as a gasoline, diesel, or natural gas powered engine) or a fuel cell. The engine 14 generates engine power and corresponding engine torque, which is supplied to the motor / gear 18 when a disconnect clutch 26 between the engine 14 and the motor / gear 18 is at least partially engaged. The motor / gear 18 may be implemented by any of a variety of types of electric machines. For example, the motor / gear 18 may be a permanent magnet synchronous motor. As will be described below, the power electronics module conditions the direct current (DC) power provided by the traction battery 20 to meet the requirements of the motor / gear 18. For example, the power electronics module may provide three-phase alternating current (AC) to the motor / gear 18.

[0014] When the disconnect clutch 26 is at least partially engaged, power flow from the engine 14 to the M / G 18 or from the M / G 18 to the engine 14 is possible. For example, the disconnect clutch 26 can be engaged, and the M / G 18 can be operated as a generator to convert rotational energy provided by the crankshaft 28 and the M / G shaft 30 into electrical energy for storage in the traction battery 20. The disconnect clutch 26 can also be disengaged to isolate the engine 14 from the rest of the powertrain 12, allowing the M / G 18 to serve as the sole drive source for the HEV 10. The shaft 30 extends through the M / G 18. The M / G 18 is continuously drivably connected to the shaft 30, whereas the engine 14 is drivably connected to the shaft 30 only when the disconnect clutch 26 is at least partially engaged.

[0015] The M / G 18 is connected to the torque converter 22 via shaft 30. Thus, when the disconnect clutch 26 is at least partially engaged, the torque converter 22 is connected to the engine 14. The torque converter 22 includes an impeller fixed to the M / G shaft 30 and a turbine fixed to the transmission input shaft 32. Thus, the torque converter 22 provides a fluid coupling between the shaft 30 and the transmission input shaft 32. The torque converter 22 transfers power from the impeller to the turbine when the impeller rotates faster than the turbine. The magnitude of the turbine torque and the impeller torque generally depends on the relative speeds. When the ratio of the impeller speed to the turbine speed is sufficiently high, the turbine torque is several times greater than the impeller torque. A torque converter bypass clutch (also known as a torque converter lockup clutch) 34 may also be provided. When engaged, the torque converter bypass clutch frictionally or mechanically connects the impeller and turbine of the torque converter 22, allowing for more efficient power transfer. The torque converter bypass clutch 34 can also function as a launch clutch to provide a smooth vehicle launch. Alternatively, or in combination, a launch clutch similar to disconnect clutch 26 may be provided between M / G 18 and gearbox 24 for applications that do not include torque converter 22 or torque converter bypass clutch 34. In some applications, disconnect clutch 26 is generally referred to as the upstream clutch, while launch clutch 34 (which may be a torque converter bypass clutch) is generally referred to as the downstream clutch.

[0016] The gearbox 24 may include a gear set (not shown) that is selectively placed in different gear ratios by selective engagement of friction elements (such as clutches and brakes) (not shown) to establish a desired plurality of discrete gear ratios or a multi-step gear ratio. The friction elements may be controlled by a shift schedule that connects and disconnects certain elements of the gear set to control the gear ratio between the transmission output shaft 36 and the transmission input shaft 32. The gearbox 24 is automatically shifted from one gear ratio to another by an associated controller (such as a powertrain control unit (PCU)) based on various vehicle operating conditions and ambient operating conditions. Power and torque from both the engine 14 and the M / G 18 may be transmitted to and received by the gearbox 24. The gearbox 24 then provides the powertrain output power and torque to the output shaft 36.

[0017] It should be understood that the hydraulically controlled gearbox 24 using a torque converter 22 is merely one example of a gearbox or transmission arrangement; any multi-ratio gearbox that receives input torque from an engine and / or motor and then provides torque to an output shaft at different gear ratios is acceptable in embodiments of the present disclosure. For example, the gearbox 24 may be implemented as an automated mechanical (or manual) transmission (AMT) that includes one or more servo motors that translate / rotate a shift fork along a shift rail to select a desired gear ratio. For example, as is generally understood by those skilled in the art, an AMT may be used in applications with higher torque requirements.

[0018] like Figure 1 In the representative embodiment shown in FIG, the output shaft 36 is connected to a differential 40. The differential 40 drives a pair of wheels 42 via corresponding axles 44 connected to the differential 40. The differential transmits approximately equal torque to each wheel 42 while allowing for slight speed differences, such as when the vehicle is turning. Different types of differentials or similar devices can be used to distribute torque from the drivetrain to one or more wheels. In some applications, for example, the torque distribution can vary depending on the specific operating mode or conditions.

[0019] The powertrain system 12 also includes an associated controller 50 (such as a powertrain control unit (PCU)). Although the controller 50 is shown as a single controller, the controller 50 may be part of a larger control system and may be controlled by various other controllers throughout the vehicle 10 (such as a vehicle system controller (VSC)). Therefore, it should be understood that the powertrain control unit 50 and one or more other controllers may be collectively referred to as a "controller," which controls various actuators in response to signals from various sensors to control multiple functions (such as starting / stopping the engine 14, operating the M / G 18 to provide wheel torque or charging the traction battery 20, selecting or scheduling transmission shifts, etc.). The controller 50 may include a microprocessor or central processing unit (CPU) that communicates with various types of computer-readable storage devices or media. The computer-readable storage devices or media may include, for example, volatile and non-volatile memory such as read-only memory (ROM), random access memory (RAM), and keyless entry memory (KAM). KAM is persistent or non-volatile memory that can be used to store various operating variables when the CPU loses power. The computer-readable storage device or medium may be implemented using any of a number of known storage devices such as PROM (programmable read-only memory), EPROM (electrically programmable read-only memory), EEPROM (electrically erasable programmable read-only memory), flash memory, or any other electrical, magnetic, optical, or combined storage device capable of storing data, some of which represents executable instructions used by the controller to control the engine or vehicle.

[0020] The controller communicates with various engine / vehicle sensors and actuators via an input / output (I / O) interface (including input channels and output channels), which may be implemented as a single integrated interface that provides various raw data or signal conditioning, processing and / or conversion, short circuit protection, etc. Optionally, one or more dedicated hardware or firmware chips may be used to condition and process specific signals before they are supplied to the CPU. As shown in Figure 1As generally shown in the representative embodiment of FIG, the controller 50 can transmit signals to and / or from the engine 14, the disconnect clutch 26, the M / G 18, the battery 20, the launch clutch 34, the transmission gearbox 24, and the power electronics module 56. Although not explicitly shown, those skilled in the art will recognize the various functions or components that can be controlled by the controller 50 within each of the above-mentioned subsystems. Representative examples of parameters, systems and / or components that may be actuated directly or indirectly using control logic and / or algorithms executed by the controller include: fuel injection timing, rate and duration, throttle position, spark plug firing timing (for spark-ignition engines), intake / exhaust valve timing and duration, front end accessory drive (FEAD) components (such as, AC generator, air conditioning compressor), battery charging or discharging (including determining maximum charging power limit and maximum discharge power limit), regenerative braking, M / G operation, clutch pressures for the disconnect clutch 26, the starting clutch 34 and the transmission gearbox 24, etc. For example, sensors transmitting inputs through the I / O interface may be used to indicate: turbocharger boost pressure, crankshaft position (PIP), engine speed (RPM), wheel speed (WS1, WS2), vehicle speed (VSS), coolant temperature (ECT), intake manifold pressure (MAP), accelerator pedal position (PPS), ignition switch position (IGN), throttle position (TP), air temperature (TMP), exhaust gas oxygen (EGO) or the concentration or presence of other exhaust gas constituents, intake air flow (MAF), transmission gear, ratio or mode, transmission oil temperature (TOT), transmission turbine speed (TS), torque converter bypass clutch 34 state (TCC), deceleration or shift mode (MDE), battery temperature, voltage, current or state of charge (SOC).

[0021] The control logic or functions performed by controller 50 may be represented by flowcharts or similar diagrams in one or more of the accompanying figures. These figures provide representative control strategies and / or logic that may be implemented using one or more processing strategies (such as event-driven, interrupt-driven, multi-tasking, multi-threading, etc.). Therefore, the various steps or functions shown may be performed in the order shown, in parallel, or omitted in some cases. Although not always explicitly shown, one of ordinary skill in the art will recognize that one or more of the steps or functions shown may be repeated depending on the specific processing strategy used. Similarly, the order of processing is not required to achieve the functions and advantages described herein, but is provided for ease of illustration and description. The control logic may be primarily implemented in software executed by a microprocessor-based vehicle, engine, and / or powertrain controller (such as controller 50). Of course, the control logic may be implemented in software, hardware, or a combination of software and hardware in one or more controllers, depending on the specific application. When implemented in software, the control logic may be provided in one or more computer-readable storage devices or media storing data representing code or instructions executed by a computer to control the vehicle or its subsystems. The computer-readable storage device or medium may include one or more of a number of known physical devices that utilize electronic, magnetic, and / or optical storage to store executable instructions and associated calibration information, operating variables, and the like.

[0022] The vehicle driver uses accelerator pedal 52 to provide the desired torque, power, or drive command to propel the vehicle. Generally speaking, depressing and releasing accelerator pedal 52 generates an accelerator pedal position signal that controller 50 interprets as a request to increase or decrease power, respectively. The vehicle driver also uses brake pedal 58 to provide the desired braking torque to slow the vehicle. Generally speaking, depressing and releasing brake pedal 58 generates a brake pedal position signal that controller 50 interprets as a request to reduce vehicle speed. Based on inputs from accelerator pedal 52 and brake pedal 58, controller 50 commands torque to engine 14, M / G 18, and friction brakes 60. Controller 50 also controls shift timing within gearbox 24, as well as the engagement or disengagement of disconnect clutch 26 and torque converter bypass clutch 34. Similar to disconnect clutch 26, torque converter bypass clutch 34 is adjustable within a range between engaged and disengaged positions. This adjustment also generates variable slip in torque converter 22, in addition to the variable slip generated by the hydraulic coupling between the impeller and turbine. Alternatively, the torque converter bypass clutch 34 may be operated to lock up or open without using the regulated operating mode, depending on the particular application.

[0023] To drive the vehicle using the engine 14, the disconnect clutch 26 is at least partially engaged to transfer at least a portion of the engine torque through the disconnect clutch 26 to the M / G 18, and then from the M / G 18 through the torque converter 22 and the gearbox 24. The M / G 18 can assist the engine 14 by providing additional power to rotate the shaft 30. This operating mode may be referred to as a "hybrid mode" or an "electric assist mode."

[0024] To propel the vehicle using the M / G 18 as the sole power source, power flow remains unchanged, except that the disconnect clutch 26 isolates the engine 14 from the rest of the drivetrain 12. During this time, combustion in the engine 14 may be disabled or otherwise shut down, thereby saving fuel. The traction battery 20 transmits stored electrical energy via wiring 54 to a power electronics module 56, which may include, for example, an inverter. The power electronics module 56 converts the DC voltage from the battery 20 to an AC voltage for use by the M / G 18. The controller 50 commands the power electronics module 56 to convert the voltage from the battery 20 to an AC voltage that is provided to the M / G 18 to provide positive or negative torque to the axle 30. This operating mode may be referred to as an "electric-only" operating mode or an "EV" operating mode.

[0025] In any operating mode, the M / G 18 can function as a motor and can provide driving force to the powertrain 12. Alternatively, the M / G 18 can function as a generator and can convert kinetic energy from the powertrain 12 into electrical energy for storage in the battery 20. For example, when the engine 14 is providing propulsion power to the vehicle 10, the M / G 18 can function as a generator. Additionally, during regenerative braking, the M / G 18 can function as a generator, during which torque and rotational energy (or kinetic energy) or power from the rotating wheels 42 are transferred back through the gearbox 24, the torque converter 22 (and / or the torque converter bypass clutch 34), and converted into electrical energy for storage in the battery 20.

[0026] The battery 20 and M / G 18 may also be configured to provide power to one or more vehicle accessories 62. Vehicle accessories 62 may include, but are not limited to, an air conditioning system, a power steering system, an electric heater, or any other system or device that is electrically operated.

[0027] An integrated starter generator (ISG) 64 may be connected to the engine 14 (i.e., may be connected to the crankshaft 28 of the engine 14). The ISG 64 may be configured to operate as a motor to start the engine 14 during an engine starting event, or to provide additional torque to the drivetrain 12 during vehicle operation. The ISG 64 may also be configured to receive torque from the engine 14 and operate as a generator. The ISG 64 may be selectively connected to the engine via a clutch 66, a belt 68, and a pair of pulleys 70. If the ISG 64 is connected to the engine via the belt 68, the ISG 64 may be referred to as a belt-driven integrated starter generator (BISG). The controller 50 may be configured to send a signal to the ISG 64 to operate the ISG 64 as a motor or a generator. The controller may also be configured to send a signal to the clutch 66 to open or close the clutch 66. When the clutch is closed, the ISG 64 is connected to the engine 14, and when the clutch 66 is open, the ISG 64 is disconnected from the engine 14. The ISG 64 can be configured to provide electrical energy to charge the accessory battery 72 and the traction battery 20 when operating as a generator, or to provide electrical energy to power the vehicle accessories 62. The accessory battery 72 can also be configured to power the vehicle accessories 62.

[0028] The exhaust system 74 is configured to direct exhaust gas generated by the engine 14 away from the vehicle 10. The exhaust system 74 may include a muffler 76 to reduce noise emitted by the exhaust system 74 and a catalytic converter 78. The catalytic converter 78 may be a motor configured to reduce carbon monoxide (CO), unburned hydrocarbons (HC), and nitrogen oxides (NOx) released into the atmosphere. X The catalyst within the catalytic converter 78 may be operable only above a light-off temperature, which is the temperature at which the catalytic reaction within the catalytic converter begins.

[0029] The controller 50 may be configured to receive the signal via an electrical signal. Figure 1 10. The electrical signals may be transmitted from the various components to the controller 50 via the input channels. Furthermore, the electrical signals received from the various components may indicate a request or command to change or transition the state of one or more corresponding components of the vehicle 10. The controller 50 includes output channels configured to transmit (via electrical signals) the requests or commands to the various vehicle components. The controller 50 includes control logic and / or algorithms configured to generate requests or commands for transmission via the output channels based on the requests, commands, conditions, or states of the various vehicle components.

[0030] exist Figure 11 and 2. Input channels and output channels are shown in dashed lines. It should be understood that a single dashed line can represent both input channels and output channels entering or leaving a single element. In addition, the output channel of one element can be operated as an input channel entering another element, and vice versa.

[0031] It should be understood that Figure 1 The schematic diagram shown in FIG is merely representative and is not intended to be limiting. Other configurations are contemplated that utilize selective engagement of both the engine and the motor to transmit power through the transmission. For example, the M / G 18 may be offset relative to the crankshaft 28, and / or the M / G 18 may be positioned between the torque converter 22 and the gearbox 24. Other configurations are contemplated without departing from the scope of this disclosure.

[0032] Reference Figure 2 , a flow chart illustrating a method 100 for controlling the vehicle powertrain 12 in accordance with an emissions reduction strategy after a cold start is shown. The controller 50 may execute the method 100 in response to various conditions of the vehicle 10 and / or various conditions of specific vehicle subcomponents. The method 100 allocates the torque output of the engine 14 and the torque output of the M / G 18 for a given driver demand torque to optimally reduce exhaust emissions while also minimizing the impact on fuel economy. The method 100 begins at start block 102 . Once the vehicle operator has activated the vehicle ignition, the method 100 may begin. Once the method 100 has begun at start block 102 , the method 100 proceeds to step 104 , where it is determined whether a coordinated emissions reduction strategy (CSER) is active. The CSER may be activated after a cold start. More specifically, the CSER may be activated if the catalytic converter temperature is below a threshold temperature. The threshold temperature may correspond to the light-off temperature of the catalytic converter 78 or to a calibrated predetermined temperature value below or above the light-off temperature. Furthermore, the CSER may remain activated as long as the temperature of the catalytic converter 78 is below a threshold temperature. If the CSER is not activated, the method 100 ends at box 106. After the method 100 has ended at box 106, the engine 14 and the M / G 18 may be controlled according to conventional methods so that the total driver demand torque is optimally distributed between the engine 14 and the M / G 18 to maximize fuel economy.

[0033] If CSER is active, the method 100 moves to box 108 where the ideal desired (or requested) torque output of the M / G 18 is calculated. The ideal desired torque output of the M / G 18 is based on the driver demand torque (i.e., the desired total torque output of the engine 14 and the M / G 18) and the optimal desired torque output of the engine 14 (or CSER torque), which is input to box 108 from box 110. The optimal desired torque output of the engine 14 is a specific steady-state torque that is calculated to provide a minimum light-off time for the catalytic converter 78 while also maintaining low (i.e., below a threshold) noise, vibration, and harshness (NVH) of the engine 14. The ideal desired torque output of the M / G 18 can be expressed by equation (1):

[0034]

[0035] in, is the ideal desired torque output of M / G 18, τ DD is the driver (or powertrain) demand torque, τ CSER is the optimum desired torque output of the engine 14 .

[0036] Once the ideal desired torque output of the M / G is calculated The method 100 then moves to box 112 where the ideal desired torque output of the M / G is determined. Is within the operating range of the M / G 18 (i.e., within the torque limits of the M / G 18, which are based on the mechanical limitations of the M / G 18 and the limitations of the battery 20 used to transmit power to or receive power from the M / G 18). The torque limits of the M / G 18 may include a maximum torque output limit and minimum torque output limit If the ideal torque output of M / G is Within the operating range of M / G18 (e.g. ), the method 100 moves to frame 114 and frame 116. In frame 114, based on the optimal desired torque output τ of the engine CSER To calculate the desired engine torque output At block 116 , based on the driver demand torque τ DD and actual or measured engine torque To calculate the desired motor torque output Desired engine torque output It can be expressed by formula (2), the desired motor torque output It can be expressed by formula (3):

[0037]

[0038]

[0039] As long as the temperature of the catalytic converter 78 remains below the threshold temperature, or as long as the desired torque output of the M / G Still within the operating range of the M / G 18, the method 100 will continue to maintain the steady-state torque of the engine (i.e., the optimal desired torque output τ of the engine) at boxes 114 and 116 according to equations (2) and (3). CSER ) and adjust the desired motor torque output To meet the driver's demand torque τ DD Once the temperature of the catalytic converter 78 exceeds the threshold temperature, the method 100 ends at box 106 where the engine 14 torque may be adjusted to meet the driver demand torque τ DD (ie, there is no longer a need to maintain the engine at steady state torque).

[0040] On the other hand, if the ideal desired torque output of the M / G Falling to meet the driver's demand torque τ DD The desired operating range of the M / G 18 is outside the desired operating range, while the temperature of the catalytic converter 78 is still below the threshold temperature, the method 100 moves to box 118. If the desired torque output of the M / G Initially outside the operating range of the M / G 18, the method 100 may immediately transition to block 118, or if the ideal desired torque output of the M / G From being within the operating range of the M / G 18 to being outside the operating range of the M / G 18, the method 100 may transition to frame 118 after controlling the torque of the engine 14 and the torque of the M / G 18 based on frames 114 and 116. Once the desired torque output of the M / G is Falling to meet the driver's demand torque τ DD If the desired operating range of the M / G 18 is exceeded and the temperature of the catalytic converter 78 remains below the threshold temperature, the torque of the M / G 18 may be adjusted to the limit (maximum or minimum) of the operating range of the M / G 18 while keeping the steady-state torque of the engine (i.e., the optimal desired torque output τ of the engine) within the desired operating range of the M / G 18. CSER ) is overridden so that the torque output of the engine 14 is adjusted to a value other than the steady-state torque to meet the driver demand torque τ DD .

[0041] At box 118, the ideal desired torque output of the M / G is determined Is it greater than the maximum torque output limit of M / G 18? If the ideal torque output of M / G is Greater than the maximum torque output limit of M / G 18 The method 100 then moves to box 120 and box 122. It should be noted that in this situation, the driver demand torque τ DD will be greater than the engine's steady-state torque (i.e., the engine's optimal desired torque output τ CSER ) and the maximum torque output limit of M / G 18 Therefore, in order to meet the driver's demand torque τ DD , it is necessary to make the desired engine torque output Increase to a value greater than the engine's steady-state torque (i.e., the engine's optimal desired torque output τ CSER ) value. At box 120, based on the driver demand torque τ DD and the maximum torque output limit of M / G 18 To calculate the desired engine torque output At box 122 , based on the driver demand torque τ DD and actual or measured engine torque Recalculate the desired motor torque output Desired engine torque output It can be expressed by formula (4), the desired motor torque output It can be expressed again by formula (3):

[0042]

[0043] At blocks 120 and 122 , the torque output of the M / G 18 will ideally be increased to the maximum torque output limit of the M / G 18 At the same time, the engine's steady-state torque (i.e., the engine's optimal desired torque output τ CSER ) is overridden so that the torque output of the engine 14 will increase to a value higher than the steady-state torque to meet the driver demand torque τ DD As long as the temperature of the catalytic converter 78 remains below the threshold temperature, or as long as the desired torque output of the M / G Still greater than the maximum torque output limit of M / G 18 The method 100 will then continue to control the torque output of the M / G 18 and the torque output of the engine 14 according to frames 120 and 122. As described above, the method 100 ends at frame 106 once the temperature of the catalytic converter 78 exceeds the threshold temperature.

[0044] On the other hand, if the ideal desired torque output of the M / G Returns to a value within the operating range of the M / G 18 (e.g. ), the method 100 may return to controlling the torque of the engine 14 and the torque of the M / G 18 based on blocks 114 and 116, or if the desired torque output of the M / G is Reduced to less than the minimum torque output limit of M / G 18 If the value of , the method 100 can control the torque of the engine 14 and the torque of the M / G 18 based on the box 126 and the box 128 (as described below). Returning to the box 118, if the ideal desired torque output of the M / G Maximum torque output limit not exceeding M / G 18 The method 100 then moves to block 124 .

[0045] At box 124 , the ideal desired torque output of the M / G is determined Is it less than the minimum torque output limit of M / G 18? If the ideal torque output of M / G is Less than the minimum torque output limit of M / G 18 The method 100 then moves to box 126 and box 128. Note that in this situation, the driver demand torque τ DD may be less than the engine's steady-state torque (i.e., the engine's optimal desired torque output τ CSER ), or may be greater than the steady-state torque of the engine but less than the steady-state torque of the engine and the minimum torque output limit of the M / G 18 The sum of the following depends on the minimum torque output limit of M / G 18 Whether it has a negative value, a positive value or a zero value. Therefore, in order to meet the driver's demand torque τ DD , the desired engine torque output The engine's optimal torque output τ CSER ) value. At box 126, based on the driver demand torque τ DD and the minimum torque output limit of M / G 18 To calculate the desired engine torque output At box 128 , based on the driver demand torque τ DD and actual or measured engine torque Recalculate the desired motor torque output Desired engine torque output It can be expressed by formula (5), the desired motor torque output It can be expressed again by formula (3):

[0046]

[0047]

[0048] At blocks 126 and 128 , the torque output of the M / G 18 will ideally be adjusted to the minimum torque output limit of the M / G 18 At the same time, the engine's steady-state torque (i.e., the engine's optimal desired torque output τ CSER ) is overridden so that the torque output of the engine 14 will be reduced to a value less than the steady-state torque to meet the driver demand torque τ DD As long as the temperature of the catalytic converter 78 remains below the threshold temperature, or as long as the desired torque output of the M / G Still less than the minimum torque output limit of M / G 18 The method 100 will continue to control the torque output of the M / G 18 and the torque output of the engine 14 according to frames 126 and 128. As described above, the method 100 ends at frame 106 once the temperature of the catalytic converter 78 exceeds the threshold temperature.

[0049] On the other hand, if the ideal desired torque output of the M / G Returns to a value within the operating range of the M / G 18 (e.g. ), the method 100 may return to controlling the torque of the engine 14 and the torque of the M / G 18 based on blocks 114 and 116. Alternatively, if the desired torque output of the M / G Increased to a maximum torque output limit greater than that of M / G 18 , the method 100 may return to controlling the torque of the engine 14 and the torque of the M / G 18 based on blocks 120 and 122 .

[0050] It should be understood that Figure 2 The flowchart in FIG is for illustration purposes only, and the method 100 should not be construed as limiting Figure 2 Some steps of method 100 may be reordered, while other steps may be omitted entirely.

[0051] In the above scenario, if the ideal torque output of M / G is Maximum torque output limit of M / G 18 Maximum calibrated value, or ideal desired torque output of M / G Minimum torque output limit for M / G 18 ratio The smallest calibrable value is the desired engine torque output Can be ramped slowly to meet driver demand torque τ DDAt the desired engine torque output Slowly ramps to meet the driver's desired torque τ DD In the case of the expected engine torque output It can be expressed by formula (6), the desired motor torque output It can be expressed again by formula (3):

[0052]

[0053]

[0054] Among them, τ EM It should be noted that when CSER is activated, the energy management torque can be set to zero.

[0055] The words used in the specification are descriptive rather than restrictive, and it should be understood that various changes may be made without departing from the spirit and scope of the present disclosure. As previously mentioned, the features of the various embodiments may be combined to form further embodiments that may not be explicitly described or shown. Although various embodiments may have been described as providing advantages or being superior to other embodiments or prior art implementations for one or more desired characteristics, it will be appreciated by those of ordinary skill in the art that, depending on the specific application and implementation, one or more features or characteristics may be compromised to achieve the desired overall system properties. Therefore, embodiments that are described as being less desirable than other embodiments or prior art implementations in one or more characteristics are not outside the scope of the present disclosure and may be expected to be used for specific applications.

Claims

1. A vehicle comprising: a powertrain having an engine and an electric motor; catalytic converter; as well as The controller is configured as: maintaining the engine torque at the steady-state engine torque output and adjusting the electric machine torque output to meet the driver demand torque in response to a temperature of the catalytic converter being less than a threshold and the driver demand torque being within a sum of an operating range of the electric machine and a predetermined steady-state engine torque output that minimizes a light-off time of the catalytic converter; In response to the temperature of the catalytic converter being less than the threshold and the driver demand torque being outside the sum of the operating range of the electric machine and the steady-state engine torque output, adjusting the electric machine torque output to a limit of the operating range of the electric machine, overriding the engine torque at which the steady-state engine torque output is maintained, and adjusting the engine torque output to meet the driver demand torque; and In response to the temperature of the catalytic converter exceeding the threshold, adjustment of engine torque output is permitted to meet driver demand torque.

2. The vehicle according to claim 1, wherein The controller is further configured to, in response to the driver demand torque being greater than the sum of the steady-state engine torque output and the maximum motor torque output during the period of maintaining the steady-state engine torque output, override the engine torque at the steady-state engine torque output to increase the engine torque output, thereby meeting the driver demand torque.

3. The vehicle according to claim 1, wherein The controller is further configured to, in response to the driver demand torque being less than the steady-state engine torque output during the period of maintaining the steady-state engine torque output, adjust the motor torque output to a minimum motor torque output, and override the engine torque at the steady-state engine torque output to reduce the engine torque output, thereby meeting the driver demand torque.

4. The vehicle according to claim 1, wherein The threshold value is the catalytic converter light-off temperature.

5. The vehicle according to claim 1, wherein The threshold value is a predetermined temperature value greater than the catalytic converter light-off temperature.

6. A vehicle comprising: an engine and an electric motor, each configured to generate torque to propel the vehicle; an engine exhaust system having a catalytic converter configured to operate above a threshold temperature; The controller is configured as: maintaining the engine torque at the steady-state engine torque output and adjusting the electric machine torque output to meet the driver demand torque in response to the temperature of the catalytic converter being below the threshold temperature and the driver demand torque being within a sum of an operating range of the electric machine and a predetermined steady-state engine torque output that minimizes a light-off time of the catalytic converter; In response to the temperature of the catalytic converter being below the threshold temperature and the driver demand torque being outside the sum of the operating range of the electric machine and the steady-state engine torque output, adjusting the torque output of the electric machine to a limit of the operating range of the electric machine, overriding the engine torque at which the steady-state engine torque output is maintained, and adjusting the engine torque output to meet the driver demand torque; and In response to the temperature of the catalytic converter exceeding the threshold temperature, adjustment of the engine torque output is permitted to meet the driver demand torque.

7. The vehicle according to claim 6, wherein: The controller is further configured to, in response to a driver demand torque being greater than the sum of the steady-state engine torque output and the maximum motor torque output during the period of maintaining the steady-state engine torque output, override the engine torque at the steady-state engine torque output to increase the engine torque output, thereby meeting the driver demand torque.

8. The vehicle according to claim 6, wherein: The controller is further configured to, in response to the driver demand torque being less than the steady-state engine torque output during the period of maintaining the steady-state engine torque output, adjust the motor torque output to a minimum motor torque output, and override the engine torque at the steady-state engine torque output to reduce the engine torque output, thereby meeting the driver demand torque.

9. The vehicle according to claim 6, wherein: The threshold temperature is a predetermined temperature value greater than a catalytic converter light-off temperature.

10. A method for controlling a vehicle powertrain system, comprising: maintaining the engine torque at the steady-state engine torque output and adjusting the electric machine torque to meet the powertrain demand torque in response to a temperature of the catalytic converter being less than a threshold and the powertrain demand torque being within a sum of an operating range of the electric machine and a predetermined steady-state engine torque output that minimizes a light-off time of the catalytic converter; In response to a temperature of the catalytic converter being less than the threshold and a powertrain demand torque falling outside a sum of an operating range of the electric machine and the steady-state engine torque output, adjusting the electric machine torque output to a limit of the operating range of the electric machine, overriding the engine torque at the steady-state engine torque output, and adjusting the engine torque output to meet the powertrain demand torque; In response to the temperature of the catalytic converter exceeding the threshold, the engine torque and the electric machine torque are adjusted to meet the powertrain torque demand.

11. The method according to claim 10, further comprising: In response to the powertrain demand torque being greater than the sum of the engine torque at the steady-state engine torque output and the maximum motor torque during the period of maintaining the steady-state engine torque output, the engine torque at the steady-state engine torque output is overridden to increase the engine torque output to meet the powertrain demand torque.

12. The method according to claim 10, further comprising: In response to the powertrain demand torque being less than the engine torque at the steady-state engine torque output during the period of maintaining the steady-state engine torque output, the motor torque is adjusted to a minimum motor torque output and the engine torque at the steady-state engine torque output is overridden to reduce the engine torque output to meet the powertrain demand torque.

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