Hybrid Vehicle Control Systems

Abstract

The present disclosure provides a "hybrid vehicle control system". A vehicle includes an engine, a motor and a controller. The engine and the motor are each configured to deliver torque to a torque converter pump wheel. The controller is programmed to increase the motor torque to a value that is less than the threshold and depends on the torque converter bypass clutch torque capacity and the torque converter turbine speed in response to the required pump wheel torque exceeding the motor torque upper threshold when the motor alone delivers torque to the pump wheel.

Description

Technical Field

[0001] The present disclosure relates to a control system for a hybrid vehicle including multiple power generation devices for propelling the vehicle. Background Art

[0002] A hybrid vehicle may include multiple electric power generation devices configured to propel the vehicle. Summary of the invention

[0003] The vehicle includes an engine, a motor, and a controller. The engine and the motor are each configured to deliver torque to a torque converter pump. The controller is programmed to increase the motor torque to a value that is less than the threshold and depends on the torque converter bypass clutch torque capacity and the torque converter turbine speed in response to the demanded pump torque exceeding the motor torque upper threshold when the motor alone delivers torque to the pump.

[0004] The vehicle includes an engine, a motor, and a controller. The engine is selectively coupled to a torque converter pump via a disconnect clutch. The motor is fixedly coupled to the pump. The controller is programmed to increase the motor torque to a value that is less than the maximum motor torque and depends on an estimated pump speed profile in response to a demand for pump torque exceeding a maximum motor torque when the disconnect clutch is open.

[0005] The vehicle includes an engine, a motor, a torque converter, and a controller. The engine is coupled to the motor via a clutch. The torque converter has an impeller coupled to the motor. The controller is programmed to increase the motor torque to a value that is less than the threshold and depends on an estimated impeller speed curve in response to an impeller torque command exceeding a threshold when the clutch is open and the engine is off. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a schematic diagram of a representative powertrain of a hybrid electric vehicle;

[0007] Figure 2 is a flow chart showing a method of adjusting the impeller torque;

[0008] Figure 3 is a graph showing impeller speed and impeller torque during engine starting; and

[0009] Figure 4 is a graph showing impeller speed, impeller torque and various other parameters during engine starting of the engine utilizing a motor / generator to start the engine. DETAILED DESCRIPTION

[0010] 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 and alternative forms. The drawings are not necessarily drawn to scale; some features may be enlarged or minimized in order to show the details of specific components. Therefore, the specific structural details and functional details disclosed herein should not be understood as restrictive, but merely as a representative basis for teaching those skilled in the art to implement these embodiments in different ways. As will be understood by those of ordinary skill in the art, the various features illustrated and described with reference to any one of the accompanying drawings may be combined with the features shown in one or more other drawings to produce embodiments that are not explicitly shown or described. The combination of features shown provides representative embodiments of typical applications. However, various combinations and modifications of features consistent with the teachings of the present disclosure may be desired for specific applications or implementations.

[0011] refer to 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 layout and orientation of the components within 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.

[0012] Both the engine 14 and the M / G 18 are drive sources for the HEV 10, which are configured to propel the HEV 10. The engine 14 generally represents a power source, which may include an internal combustion engine such as a gasoline, diesel or natural gas powered engine or a fuel cell. When the disconnect clutch 26 between the engine 14 and the M / G 18 is at least partially engaged, the engine 14 generates engine power and corresponding engine torque that are provided to the M / G 18. The M / G 18 can be implemented by any of a variety of types of motors. For example, the M / G 18 can be a permanent magnet synchronous motor. The power electronics adjust the direct current (DC) power provided by the battery 20 according to the requirements of the M / G 18, as described below. For example, the power electronics can provide three-phase alternating current (AC) to the M / G 18.

[0013] When the disconnect clutch 26 is at least partially engaged, power can flow from the engine 14 to the M / G 18 or from the M / G 18 to the engine 14. For example, the disconnect clutch 26 can be engaged and the M / G 18 can be operated as a generator to convert the rotational energy provided by the crankshaft 28 and the M / G shaft 30 into electrical energy to be stored in the battery 20. The disconnect clutch 26 can also be disengaged to isolate the engine 14 from the rest of the powertrain 12 so that the M / G 18 can 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, while the engine 14 is drivably connected to the shaft 30 only when the disconnect clutch 26 is at least partially engaged.

[0014] The M / G 18 is connected to the torque converter 22 via the 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 a pump wheel fixed to the M / G shaft 30 and a turbine fixed to the transmission input shaft 32. Thus, the torque converter 22 provides a hydraulic connection between the shaft 30 and the transmission input shaft 32. When the pump wheel rotates faster than the turbine, the torque converter 22 transfers power from the pump wheel to the turbine. The magnitude of the turbine torque and the pump wheel torque generally depends on the relative speed. When the ratio of the pump wheel speed to the turbine speed is high enough, the turbine torque is a multiple of the pump wheel torque. A torque converter bypass clutch (also known as a torque converter lockup clutch) 34 may also be provided, which frictionally or mechanically couples the pump wheel and turbine of the torque converter 22 when engaged, allowing more efficient power transmission. The torque converter bypass clutch 34 may be operated as a starting clutch to provide a smooth vehicle launch. Alternatively or in combination, for applications that do not include a torque converter 22 or a torque converter bypass clutch 34, a launch clutch similar to the disconnect clutch 26 may be provided between the M / G 18 and the transmission 24. In some applications, the disconnect clutch 26 is generally referred to as the upstream clutch, and the launch clutch 34 (which may be a torque converter bypass clutch) is generally referred to as the downstream clutch.

[0015] The gearbox 24 may include gear sets (not shown) that are selectively placed in different gear ratios through the selective engagement of friction elements such as clutches and brakes (not shown) to establish a desired plurality of discrete or stepped transmission ratios. The friction elements may be controlled by a shift schedule that connects and disconnects certain elements of the gear set to control the transmission ratio between the transmission output shaft 36 and the transmission input shaft 32. Based on various vehicle and environmental conditions, the transmission 24 is automatically shifted from one transmission ratio to another by an associated controller such as a powertrain control unit (PCU). Power and torque from the engine 14 and the M / G 18 may be delivered to and received by the gearbox 24. The gearbox 24 then provides the powertrain output power and torque to the output shaft 36.

[0016] It should be understood that the hydraulically controlled transmission 24 used with the torque converter 22 is only one example of a transmission or transmission device; any multi-ratio transmission that accepts one or more input torques from an engine and / or motor and then provides torque to an output shaft at different gear ratios can be used in embodiments of the present disclosure. For example, the transmission 24 can be implemented by an automated mechanical (or manual) transmission (AMT), which includes one or more servomotors to translate / rotate a shift fork along a shift rail to select a desired gear ratio. As is generally understood by those of ordinary skill in the art, an AMT can be used, for example, in applications with higher torque requirements.

[0017] like Figure 1 As shown in the representative embodiment of FIG. 4 , the output shaft 36 is connected to a differential 40. The differential 40 drives a pair of wheels 42 via respective shafts 44 connected to the differential 40. The differential transmits approximately equal torque to each wheel 42, but allows 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, the torque distribution can vary depending on, for example, a particular operating mode or condition.

[0018] The powertrain system 12 also includes an associated controller 50 such as a powertrain control unit (PCU). Although shown as one 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). It should therefore be understood that the powertrain control unit 50 and one or more other controllers may be collectively referred to as a "controller" that controls various actuators in response to signals from various sensors to control functions such as starting / stopping the engine 14, operating the M / G 18 to provide wheel torque or charging the 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 in the form of read-only memory (ROM), random access memory (RAM), and keep-alive memory (KAM). KAM is a persistent or non-volatile memory that can be used to store various operating variables when the CPU is powered off. The computer readable storage device or medium may be implemented using any of a number of known memory devices, such as a PROM (programmable read-only memory), EPROM (electronic PROM), EEPROM (electrically erasable PROM), flash memory, or any other electronic, magnetic, optical, or combination memory device capable of storing data, some of which represent executable commands used by the controller to control the engine or vehicle.

[0019] The controller communicates with various engine / vehicle sensors and actuators through an input / output (I / O) interface (including input channels and output channels), which can be implemented as a single integrated interface that provides various raw data or signal conditioning, processing and / or conversion, short circuit protection, etc. Alternatively, one or more dedicated hardware or firmware chips can be used to condition and process specific signals before being provided to the CPU. Typically, Figure 1As shown in the representative embodiment of FIG. 1 , the controller 50 may 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 56. Although not explicitly described, one of ordinary skill in the art will recognize the various functions or components that may be controlled by the controller 50 in each of the subsystems identified above. Representative examples of parameters, systems, and / or components that may be directly or indirectly actuated 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 an alternator), air conditioning compressor, battery charging or discharging (including determining maximum charge and discharge power limits), regenerative braking, M / G operation, disconnect clutch 26, launch clutch 34, and clutch pressures of the transmission gearbox 24, etc. Sensors transmitting inputs through the I / O interface may be used, for example, 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 other exhaust gas constituent concentration or presence, intake air flow (MAF), transmission gear, 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).

[0020] The control logic or functions performed by the controller 50 may be represented by a flowchart or similar diagram in one or more of the accompanying drawings. These figures provide representative control strategies and / or logic that can be implemented using one or more processing strategies, such as event-driven, interrupt-driven, multi-tasking, multi-threading, etc. In this way, the various steps or functions shown may be performed in the order shown, in parallel, or omitted in some cases. Although not always explicitly stated, it will be recognized by those of ordinary skill in the art that one or more of the steps or functions shown may be repeated according to the specific processing strategy used. Similarly, the processing order is not necessarily required to achieve the features and advantages described herein, but is provided for ease of illustration and description. The control logic may be implemented primarily in software executed by a microprocessor-based vehicle, engine and / or powertrain controller (e.g., controller 50). Of course, depending on the specific application, the control logic may be implemented in software, hardware, or a combination of software and hardware in one or more controllers. When implemented in software, the control logic may be provided in one or more computer-readable storage devices or media having stored data representing codes or commands executed by a computer to control a vehicle or its subsystems. Computer-readable storage devices or media may include one or more of a variety of known physical devices that utilize electrical, magnetic, and / or optical storage to maintain executable instructions and related calibration information, operating variables, and the like.

[0021] The vehicle driver uses the accelerator pedal 52 to provide a demand torque, power or drive command to propel the vehicle. Generally, depressing and releasing the accelerator pedal 52 generates an accelerator pedal position signal, which can be interpreted by the controller 50 as a demand for increasing power or decreasing power, respectively. The vehicle driver also uses the brake pedal 58 to provide a demand braking torque to slow the vehicle. Generally, depressing and releasing the brake pedal 58 generates a brake pedal position signal, which can be interpreted by the controller 50 as a demand for reducing vehicle speed. Based on inputs from the accelerator pedal 52 and the brake pedal 58, the controller 50 commands torque to the engine 14, the M / G 18 and the friction brake 60. The controller 50 also controls the timing of shifting gears in the gearbox 24, and the engagement or disengagement of the disconnect clutch 26 and the torque converter bypass clutch 34. Like the disconnect clutch 26, the torque converter bypass clutch 34 can be adjusted across a range between an engaged position and a disengaged position. In addition to the variable slip generated by the hydraulic coupling between the impeller and the turbine, this also generates variable slip in the torque converter 22. Alternatively, torque converter bypass clutch 34 may be operated in a locked or open state without using a regulated operating mode, depending on the particular application.

[0022] To drive the vehicle with the engine 14, the disconnect clutch 26 is at least partially engaged to transfer at least a portion of the engine power and / or torque to the M / G 18 through the disconnect clutch 26, and then from the M / G 18 to the shaft 30 (i.e., the pump impeller of the torque converter 22) and through the torque converter 22 and the transmission 24. The M / G 18 can assist the engine 14 by providing additional power and / or torque to rotate the shaft 30 (i.e., the pump impeller of the torque converter 22). This operating mode may be referred to as a "hybrid mode" or an "electric assist mode".

[0023] To drive the vehicle with the M / G 18 as the sole power source, the power flow remains the same except that the disconnect clutch 26 isolates the engine 14 from the rest of the powertrain 12. During this time, combustion in the engine 14 may be disabled or otherwise shut down to save fuel. The traction battery 20 transmits the stored electrical energy to the power electronics 56, which may include, for example, an inverter, via wiring 54. The power electronics 56 converts the DC voltage from the battery 20 into an AC voltage to be used by the M / G 18. The controller 50 commands the power electronics 56 to convert the voltage from the battery 20 into an AC voltage that is provided to the M / G 18 to provide positive or negative power and / or torque to the shaft 30 (i.e., the pump wheel of the torque converter 22). This operating mode may be referred to as an "electric only" or "EV" operating mode.

[0024] In either operating mode, the M / G 18 can function as a motor and provide drive to the powertrain 12. Alternatively, the M / G 18 can function as a generator and convert kinetic energy from the powertrain 12 into electrical energy to be stored in the battery 20. For example, the M / G 18 can function as a generator when the engine 14 is providing propulsion power to the vehicle 10. The M / G 18 can additionally function as a generator during regenerative braking, in which torque and rotational (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 to be stored in the battery 20.

[0025] The battery 20 and M / G 18 may also be configured to provide power to one or more vehicle accessories 62. The vehicle accessories 62 may include, but are not limited to, an air conditioning system, a power steering system, an electric heater, or any other electrically operated system or device.

[0026] An integrated starter-generator (ISG) 64 may be coupled to the engine 14 (i.e., may be coupled 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 powertrain 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 coupled to the engine via a clutch 66, a belt 68, and a pair of pulleys 70. If the ISG 64 is coupled to the engine via a belt 68, it may be referred to as a belt integrated starter-generator (BISG). The controller 50 may be configured to transmit a signal to the ISG 64 to operate the ISG 64 as a motor or a generator. The controller may also be configured to transmit a signal to the clutch 66 to open or close the clutch 66. The ISG 64 will be coupled to the engine 14 when the clutch is in the closed state, and will be decoupled from the engine 14 when the clutch 66 is in the open state. The ISG 64 can be configured to provide electrical energy to charge the accessory battery 72, the traction battery 20, or to provide electrical energy to power the vehicle accessories 62 when operating as a generator. The accessory battery 72 can also be configured to power the vehicle accessories 62.

[0027] The controller 50 may be configured to receive the Figure 1 10. The controller 50 may include an output channel configured to deliver (via electrical signals) requests or commands to various vehicle components. The controller 50 may include control logic and / or algorithms configured to generate requests or commands delivered via output channels based on requests, commands, conditions, or states of various vehicle components.

[0028] Input channels and output channels are as follows Figure 1 It should be understood that a single dotted line can represent an input channel and an output channel into and out of a single element. In addition, an output channel in one element can serve as an input channel in another element, and vice versa.

[0029] It should be understood that Figure 1The schematic diagrams shown in are merely representative and are not intended to be limiting. Other configurations are contemplated that utilize selective engagement of an engine and a motor to transmit power through a transmission. For example, the M / G 18 may be offset from the crankshaft 28, and / or the M / G 18 may be disposed between the torque converter 22 and the transmission 24. Other configurations are contemplated without departing from the scope of the present disclosure.

[0030] refer to Figure 2 , a method 200 for adjusting the impeller torque is shown. The method 200 may be stored as an algorithm and / or control logic within the controller 50. The controller 50 may be configured to implement the control method 200 based on various conditions of the HEV 10 or various subsystems of the HEV 10. The method 200 is initiated at a start box 202. Once the method 200 has been initiated, the method 200 proceeds to box 204, where the torque reserve of the M / G 18 is set to zero. The torque reserve of the M / G 18 may refer to the amount of torque reserved for starting the engine 14, which may occur by transferring torque from the M / G 18 to the engine 14 via closing the disconnect clutch 26.

[0031] After setting the torque reserve of the M / G 18 to zero at box 204, the method 200 proceeds to box 205 where the driver demand torque is determined. The driver demand torque may be determined based on an operator input (e.g., a commanded torque via a depressing of the accelerator pedal 52) and may be specified in the impeller torque domain, the turbine torque domain, or the wheel torque domain.

[0032] The method 200 then proceeds to box 206 where the impeller speed of the torque converter 22 required to meet the driver demand torque is estimated. The driver demand torque may be gradually increased according to a filtering function or a shaping function (such as an anti-shudder function) so that the powertrain operates in a smooth manner to minimize noise, vibration, and harshness. If the driver demand torque is specified in the turbine domain, the impeller speed required to meet the driver demand torque at the turbine may be calculated using equation (1):

[0033] τ 涡轮 =K(ω i ) 2 +τ 旁通离合器 (1)

[0034] Where: τ 涡轮 is the driver demand torque at the turbine of the torque converter 22, τ 旁通 is the torque capacity of the torque converter bypass clutch 34, ω i is the pump speed of the torque converter 22, and K is the K factor of the torque converter 22, which is the turbine speed ω of the torque converter 22. t and the pump speed ω i function.

[0035] The driver demand torque specified in the wheel domain can be converted into the driver demand torque at the turbine τ 涡轮 , the conversion uses equation (2):

[0036]

[0037] where RT is the transmission torque ratio, and τ 车轮 is the driver demand torque at wheels 42 .

[0038] The driver demand torque specified in the turbine domain can be converted to the driver demand torque at the impeller, and vice versa, using equation (3):

[0039] τ 涡轮 =Rτ 泵轮 (3)

[0040] Where R is the torque ratio across the torque converter 22, and τ 泵轮 is the driver demand torque at the pump of the torque converter 22. The torque ratio R across the torque converter is the pump speed ω of the torque converter 22 i and the turbine speed ω of the torque converter 22 t function.

[0041] Expected driver demand torque at turbine τ 涡轮 , torque converter bypass clutch capacity τ 旁通 and turbine speed ω t The torque converter bypass clutch capacity τ may be known via operator input (e.g., via commanded torque from depressing an accelerator pedal) or via instrumentation (e.g., a torque or speed sensor). Based on the known value of the driver demand torque in any desired domain (e.g., wheels, a pump of a torque converter, or a turbine of a torque converter), the torque converter bypass clutch capacity τ 旁通 and turbine speed ω t , the controller 50 can estimate the torque τ that satisfies the driver's demand at the turbine 涡轮 The pump speed ω i , which is estimated using equation (1) and, if necessary, equations (2) and (3).

[0042] Once the estimated pump speed ω i has been determined, method 200 proceeds to block 208 where it is estimated that the impeller speed ω i The power loss of the M / G 18 determined at box 208 may refer to the electrical loss caused by: i The low efficiency of M / G 18 at the estimated pump speed ω iThe inefficiency of the lower power electronics 56 and / or the required torque command being equal to the required pump torque τ 泵轮 The sum of the losses and the motor torque reserve.

[0043] After determining the power loss of the M / G 18 at box 208, the method 200 proceeds to box 210 where the maximum sustainable torque of the M / G 18 is estimated given: the estimated speed of the M / G 18 (which corresponds to the estimated impeller speed ω i , because the M / G 18 and the impeller are fixed on a common shaft 30 ), the power loss of the M / G 18 determined at box 208 , the required impeller torque τ 泵轮 , and the power limit of the traction battery 20 (which may include the maximum power output or discharge limit of the traction battery 20, the current charge of the traction battery 20, and the duration for which a specific power output or discharge of the traction battery 20 can be maintained given the current battery charge, etc.). It should be noted that since the maximum sustainable torque of the M / G 18 depends on the estimated pump wheel speed ω i , according to equation (1) above, the maximum sustainable torque of the M / G 18 will also depend on the driver demand torque τ at the turbine 涡轮 , torque converter bypass clutch capacity τ 旁通 and turbine speed ω t Assume that the net impeller torque is equal to the required impeller torque τ 泵轮 Maximum sustainable motor torque and required pump torque τ 泵轮 The difference between can be used to compensate for the negative torque of disconnect clutch 26, since the net impeller torque will remain unchanged.

[0044] During the condition that the engine 14 is starting and the disconnect clutch 26 is closing while the M / G 18 is running, the maximum sustainable torque of the M / G 18 determined at block 210 may correspond to a maximum torque value of the M / G 18 that is sustainable for a period of time corresponding to ramping the engine speed up to the impeller speed ω during engine starting. i .

[0045] The method 200 then proceeds to block 212 where the torque at the impeller is limited. More specifically, the torque at the impeller may be limited to the minimum of the following two values: (1) the driver demand torque τ at the impeller 泵轮and (2) the sum of the torque of the engine 14 transmitted through the disconnect clutch 26 (if connected) and the maximum sustainable torque of the M / G 18 determined at box 210 minus the torque reserve of the M / G 18. If the engine speed is less than the impeller speed, the torque of the engine 14 transmitted through the disconnect clutch 26 is zero. If the engine speed is not less than the impeller speed, the torque of the engine 14 transmitted through the disconnect clutch 26 is the minimum of the capacity of the disconnect clutch 26 and the maximum engine torque. During the situation where the M / G 18 is solely powering the HEV 10, if the engine 14 can be commanded to start, a portion of the M / G 18 torque (i.e., the torque reserve) can be reserved. If the engine 14 is commanded to start, the torque reserve can be transferred from the M / G 18 to the engine 14 by closing the disconnect clutch 26 to assist the engine during the starting process. To minimize the time from cranking the engine 14 during starting to connecting the engine 14 to the rest of the powertrain 12 via the disconnect clutch 26, a limited amount of capacity of the disconnect clutch 26 may be requested before the engine 14 reaches synchronous speed with the M / G 18. The M / G 18 may compensate for the limited amount of capacity of the disconnect clutch 26 that has been requested, as long as the capacity is less than the torque reserve.

[0046] Furthermore, during situations where the M / G 18 is solely powering the HEV 10 (ie, the engine 14 is off and the disconnect clutch 26 is open), if the driver demand torque τ at the impeller 泵轮 Exceeding the instantaneous maximum torque output potential of the M / G 18 (which may be referred to as an upper threshold, based on the maximum power output of the traction battery 20, and greater than the maximum sustainable torque of the M / G 18 determined at box 210), the torque of the M / G 18 may be increased to the maximum sustainable torque of the M / G 18 determined at box 210, or, if a reserve is available, to the maximum sustainable torque of the M / G 18 determined at box 210 minus the reserve. The M / G 18 may also be increased in response to the driver demand torque τ at the pump wheel. 泵轮 Beyond the instantaneous maximum torque output potential of the M / G 18 , the disconnect clutch 26 is commanded to close in order to start the engine 14 and connect the engine 14 to the powertrain 12 .

[0047] After limiting the impeller torque at box 212, the method 200 proceeds to box 214, where it is determined whether a request to start the engine 14 has been received. If a request to start the engine 14 has been received, the method 200 proceeds to box 216, where it is determined how much torque of the M / G 18 is available to assist the engine 14 during engine starting. The amount of torque of the M / G 18 available to assist the engine 14 during engine starting may be equal to or less than the maximum sustainable torque of the M / G 18 determined at box 210 and the torque currently being commanded to the M / G 18 (equal to the current demand torque τ at the impeller).泵轮 Next, the method 200 proceeds to block 218 where it is determined how much torque of the M / G 18 is desired to be used to assist the engine 14 during engine starting.

[0048] After determining how much torque of the M / G 18 is available and desired for assisting the engine 14 during engine starting at frames 216 and 218, respectively, the method 200 proceeds to frame 220. At frame 220, the amount of torque of the M / G 18 available to assist the engine 14 during engine starting and the amount of torque of the M / G 18 desired for assisting the engine 14 are arbitrated, and the appropriate amount of torque of the M / G 18 is reserved for assisting the engine 14 during engine starting. During the arbitration, if the amount of torque of the M / G 18 available for assisting the engine 14 during engine starting is less than the desired torque of the M / G 18, the amount of reserve torque is set to the amount of torque of the M / G 18 available to assist the engine 14 during engine starting. On the other hand, if the amount of torque available from the M / G 18 is greater than the desired torque of the M / G 18 to assist the engine 14 during engine starting, the reserve torque amount is set to the amount of torque desired from the M / G 18 to assist the engine 14 during engine starting.

[0049] Once the arbitration step at frame 220 is completed, the method 200 proceeds to frame 222, where the desired or requested torque capacity of the disconnect clutch 26 during engine starting is generated. If the desired or requested disconnect clutch 26 capacity is less than the available torque of the M / G 18 used to assist the engine 14 during engine starting (determined at frame 216), the motor torque reserve can be set to the desired or requested torque capacity of the disconnect clutch 26. If the desired or requested disconnect clutch 26 capacity is greater than the available torque of the M / G 18 used to assist the engine 14 during engine starting, the disconnect clutch 26 capacity is reduced to the available torque of the M / G 18 to prevent the impeller torque from dropping. Once the desired or requested torque capacity of the disconnect clutch 26 during engine starting is generated, the method 200 returns to the input of frame 205.

[0050] Returning to frame 214, if a request to start the engine 14 has not been received, the method 200 proceeds to frame 224, where it is determined whether an engine start is in progress. If an engine start is in progress, the method 200 proceeds directly to frame 222. On the other hand, if an engine start is not in progress, the method 200 returns to the input of frame 204. It should be understood that Figure 2 The flowchart in FIG. 2 is for illustration purposes only, and the method 200 should not be construed as being limited to Figure 2 Some steps of method 200 may be rearranged, while other steps may be omitted entirely.

[0051] refer to Figure 3 , a graph 300 of impeller speed and impeller torque during engine starting is shown. The engine starting may correspond to a depression of the accelerator pedal 52. Line 302 corresponds to the unfiltered or unshaped driver demand impeller torque. Line 304 corresponds to the instantaneous maximum torque output potential of M / G 18 that may be delivered to the impeller when the torque of M / G 18 is not limited according to the maximum sustainable torque of M / G 18. Line 305 corresponds to the instantaneous maximum torque output potential of M / G 18 that may be delivered to the impeller when the torque of M / G 18 is limited according to the maximum sustainable torque of M / G 18. Line 306 corresponds to the torque delivered to the impeller when the torque of M / G 18 is commanded according to the instantaneous maximum torque output potential of M / G 18. Line 308 corresponds to the impeller speed response when the torque of M / G 18 is commanded according to the instantaneous maximum torque output potential of M / G 18. Line 310 corresponds to the impeller speed response corresponding to raising the engine speed to the estimated impeller speed ω i The maximum sustainable torque of the M / G 18 during the time period (see box 210). Line 312 corresponds to the maximum sustainable torque of the M / G 18 during the time period (see box 210). 泵轮 The torque of the M / G 18 is commanded (see block 206) and has been limited to the torque delivered to the impeller at the maximum sustainable torque of the M / G 18 during engine starting. Line 314 is the estimated impeller speed ω i (See box 206.) Line 316 corresponds to the impeller speed response when the torque of the M / G 18 is limited to the maximum sustainable torque of the M / G 18 (see box 210). Line 318 shows the filtered or shaped torque curve if the engine 14 had delivered torque to the impeller.

[0052] At time t0, the vehicle operator increases the torque demand 302 to a value that exceeds the maximum torque output of the M / G 18, which results in the initiation of an engine start at time t1. When torque is delivered to the impeller according to line 312 (wherein the torque at the impeller is τ 泵轮 The torque of the M / G 18 is commanded and limited to a value corresponding to bringing the engine speed up to the estimated impeller speed ω. iThe maximum sustainable torque of the M / G 18 during the time period of t3), the engine 14 begins to deliver torque to the impeller at time t3, which results in the required impeller torque 302 being obtained at time t5 (before time t3, only the M / G 18 delivers torque to the impeller along line 312). When torque is delivered to the impeller according to line 306 (where the torque of the M / G 18 is commanded according to the instantaneous maximum torque output potential of the M / G 18), the engine 14 begins to deliver torque to the impeller at time t4, which results in the required impeller torque 302 being obtained at time t6 (before time t4, only the M / G 18 delivers torque to the impeller along line 306). Therefore, according to the estimated driver demand torque τ at the impeller 泵轮 Commanding and limiting the torque of the M / G 18 to the maximum sustainable torque of the M / G 18 results in the engine 14 starting and achieving the requested impeller torque 302 earlier than when the torque of the M / G 18 was commanded according to the instantaneous maximum torque output potential of the M / G 18 .

[0053] refer to Figure 4 , a graph 400 of impeller speed, impeller torque, and various other parameters during an engine start of the engine 14 using the M / G 18 is shown. The engine start may correspond to a depression of the accelerator pedal 52. Line 402 corresponds to the unfiltered or unshaped driver demand impeller torque. Line 404 corresponds to the instantaneous maximum torque output potential of the M / G 18 that can be delivered to the impeller. Line 406 corresponds to the torque delivered to the impeller via the M / G 18 when the torque of the M / G 18 is commanded according to the maximum sustainable torque of the M / G 18 when there is no reserve M / G 18 torque to assist during engine run-up. Line 408 corresponds to the impeller speed response when the torque of the M / G 18 is commanded according to the instantaneous maximum torque output potential of the M / G 18. Line 410 corresponds to the impeller speed response corresponding to raising the engine speed to the estimated impeller speed ω i The maximum sustainable torque of the M / G 18 during the time period of (see box 210). Line 412 corresponds to the torque delivered to the impeller when the disconnect clutch 26 is used to assist the engine to speed up and the M / G 18 torque delivered to the impeller is limited to the maximum sustainable torque of the M / G 18 minus the torque reserve required to start the engine 14. Line 414 is the estimated impeller speed ω when there is a torque reserve to assist the engine 14 to speed up. i(See box 206). Line 416 corresponds to the impeller speed response when the torque of M / G 18 is limited to the maximum sustainable torque of M / G 18 (see box 210) when there is no torque reserve to assist the engine 14 to speed up. Line 418 corresponds to the impeller speed response when the torque of M / G 18 is limited to the maximum sustainable torque of M / G 18 when the torque from the disconnect clutch 26 is used to assist the engine 14 to speed up. Line 420 is the M / G 18 torque reserved to assist the engine 14 to speed up. Line 422 is the maximum torque of M / G 18 that can be reserved for engine 14 to speed up. Line 424 is the maximum torque of M / G 18 that can be delivered to the impeller when there is torque reserved to assist the engine 14 to speed up, which is the difference between the maximum sustainable torque of M / G 18 shown in line 410 and the torque reserve 420. Line 426 shows the torque curve if the engine 14 has delivered torque to the impeller.

[0054] Figure 4 Followed by Figure 3 Same mode, except during engine starting between time t1 and t3 , the torque of the M / G 18 is limited to the adjusted maximum sustainable torque of the M / G 18 of line 424 rather than the maximum sustainable torque of the M / G 18 of line 410 , which allows the reserve torque 420 to be used to start the engine 14 .

[0055] The words used in the specification are descriptive rather than limiting, 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 other embodiments that may not be explicitly described or illustrated. Although various embodiments may be described as providing advantages or superiority with respect to one or more desired characteristics relative to other embodiments or prior art implementations, those of ordinary skill in the art recognize that one or more features or characteristics may be compromised to achieve the desired overall system properties, depending on the specific application and implementation. Therefore, embodiments that are described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are within the scope of the present disclosure and may be desirable for particular applications.

[0056] According to the present invention, a vehicle is provided, which has an engine and a motor, each configured to deliver torque to a torque converter pump wheel; and a controller, which is programmed to increase the motor torque to a value that is less than the threshold and depends on the torque capacity of the torque converter bypass clutch and the torque converter turbine speed in response to the required pump wheel torque exceeding the motor torque upper threshold when the motor alone delivers torque to the pump wheel.

[0057] According to one embodiment, the invention is further characterized by a battery configured to power the motor, wherein the value is further dependent on a battery discharge limit.

[0058] According to one embodiment, the present invention is further characterized by a disconnect clutch configured to selectively couple the engine to the impeller, wherein the controller is programmed to close the disconnect clutch and start the engine in response to the required impeller torque exceeding the threshold when the motor alone delivers torque to the impeller.

[0059] According to one embodiment, the value corresponds to a motor torque value that is sustainable over a period of time corresponding to ramping up the engine speed to an estimated impeller speed during engine starting.

[0060] According to one embodiment, a portion of the motor torque is transferred via the disconnect clutch to assist in starting the engine.

[0061] According to one embodiment, the portion of the motor torque transmitted by the disconnect clutch is smaller than or equal to the difference between the value and the current motor torque.

[0062] According to the present invention, a vehicle is provided, which has an engine, which is selectively connected to a torque converter pump wheel via a disconnect clutch; a motor, which is fixedly connected to the pump wheel; and a controller, which is programmed to increase the motor torque to a value that is less than the maximum sustainable motor torque and depends on an estimated pump wheel speed curve in response to the required pump wheel torque exceeding the maximum sustainable motor torque when the disconnect clutch is open.

[0063] According to one embodiment, the invention is further characterized by a battery configured to power the motor, wherein the value is further dependent on a battery discharge limit.

[0064] According to one embodiment, the controller is programmed to close the disconnect clutch and start the engine in response to the required impeller torque exceeding the maximum sustainable motor torque when the disconnect clutch is open.

[0065] According to one embodiment, said value corresponds to a motor torque value which is sustainable over a period of time corresponding to ramping up said engine speed to said estimated impeller speed during engine starting.

[0066] According to one embodiment, a portion of the motor torque is transferred via the disconnect clutch to start the engine.

[0067] According to one embodiment, the portion of the motor torque transmitted by the disconnect clutch is smaller than or equal to the difference between the value and the current motor torque.

[0068] According to one embodiment, the present invention is further characterized by a torque converter bypass clutch, wherein the estimated impeller speed curve is further derived from the torque capacity of the bypass clutch, the torque converter turbine speed and the required torque converter turbine torque.

[0069] According to the present invention, a vehicle is provided having an engine connected to a motor via a clutch; a torque converter having an impeller connected to the motor; and a controller programmed to increase the motor torque to a value less than the threshold and dependent on an estimated impeller speed curve in response to an impeller torque command exceeding a threshold when the clutch is open and the engine is off.

[0070] According to one embodiment, the invention is further characterized by a battery configured to power the motor, wherein the value is further dependent on a battery discharge limit.

[0071] According to one embodiment, the controller is programmed to close the clutch and start the engine in response to the impeller torque command exceeding the threshold when the clutch is open and the engine is off.

[0072] According to one embodiment, said value corresponds to a motor torque value which is sustainable over a period of time corresponding to ramping up said engine speed to said estimated impeller speed during engine starting.

[0073] According to one embodiment, a portion of the motor torque is transferred through the clutch to assist in starting the engine.

[0074] According to one embodiment, said portion of said motor torque is smaller than or equal to a difference between said threshold value and a current motor torque.

[0075] According to one embodiment, the present invention is further characterized by a torque converter bypass clutch, and wherein the estimated impeller speed curve is based on the torque capacity of the bypass clutch, the torque converter turbine speed and the required torque converter turbine torque.

Claims

1. A vehicle comprising: an engine and a motor, each configured to transmit torque to a pump impeller of a torque converter; as well as A controller is configured to: in response to a required impeller torque exceeding a motor torque upper threshold when the motor alone transmits torque to the impeller, increase the motor torque to a value less than the motor torque upper threshold, the value being based on a torque converter bypass clutch torque capacity and a torque converter turbine speed. 2 . The vehicle of claim 1 , further comprising a battery configured to provide power to the motor, wherein the value is further based on a battery discharge limit.

3. The vehicle as described in claim 2 further includes a disconnect clutch configured to selectively connect the engine to the impeller, wherein the controller is configured to: in response to the required impeller torque exceeding the motor torque upper threshold when the motor alone transmits torque to the impeller, close the disconnect clutch and start the engine.

4. The vehicle according to claim 3, wherein: The value corresponds to a motor torque value that is sustainable over a period of time corresponding to ramping the engine speed up to an estimated impeller speed during engine starting.

5. The vehicle of claim 1, wherein: The value is also based on the requested torque converter turbine torque.

6. A vehicle comprising: an engine selectively coupled to a pump impeller of a torque converter via a disconnect clutch; a motor fixedly coupled to the pump impeller; Torque converter bypass clutch; as well as a controller configured to, in response to a demand for an impeller torque exceeding a maximum sustainable motor torque when the disconnect clutch is open, increase the motor torque to a value less than the maximum sustainable motor torque, the value being based on an estimated impeller speed profile, Among them, the estimated impeller speed curve is based on the torque capacity of the torque converter bypass clutch, the torque converter turbine speed and the required torque converter turbine torque.

7. The vehicle of claim 6, further comprising a battery configured to provide power to the motor, wherein the value is further based on a battery discharge limit.

8. The vehicle of claim 7, wherein: The controller is configured to, in response to the required impeller torque exceeding the maximum sustainable motor torque when the disconnect clutch is open, close the disconnect clutch and start the engine.

9. The vehicle of claim 8, wherein: The value corresponds to a motor torque value that is sustainable over a period of time corresponding to ramping the engine speed up to an estimated impeller speed during engine starting.

10. The vehicle of claim 8, wherein: A portion of the motor torque is transferred through the disconnect clutch to start the engine.

11. The vehicle of claim 10, wherein: The portion of the motor torque transmitted through the disconnect clutch is less than or equal to a difference between the value and a current motor torque.

12. A vehicle comprising: an engine coupled to the motor via a clutch; a torque converter having an impeller coupled to the motor; Torque converter bypass clutch; as well as a controller configured to, in response to an impeller torque command exceeding a threshold when the clutch is open and the engine is off, increase the motor torque to a value less than the threshold, the value being based on an estimated impeller speed profile, Among them, the estimated impeller speed curve is based on the torque capacity of the torque converter bypass clutch, the torque converter turbine speed and the required torque converter turbine torque.

13. The vehicle of claim 12, wherein: The controller is configured to, in response to the impeller torque command exceeding the threshold when the clutch is open and the engine is off, close the clutch and start the engine.

14. The vehicle of claim 13, wherein: The value corresponds to a motor torque value that is sustainable over a period of time corresponding to ramping the engine speed up to an estimated impeller speed during engine starting.

15. The vehicle of claim 12, wherein: A portion of the motor torque is transmitted through the clutch to start the engine, the portion of the motor torque transmitted through the clutch being less than or equal to a difference between the value and a current motor torque.

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