Hybrid vehicles

Abstract

To suppress deviation of an actual output torque of a motor from an actually required motor torque when an estimated output torque of an engine deviates from an actual output torque of the engine.SOLUTION: A hybrid vehicle comprises an engine coupled to a drive shaft, a motor coupled to the drive shaft, a battery for exchanging electric power with the motor, and a control device. The control device sets an upper limit torque and a lower limit torque of the motor such that a difference between a torque command indicating a torque to be output to the drive shaft and an actual torque output to the drive shaft is within an allowable range on the basis of an operating state of the hybrid vehicle, and controls the motor so as to output the torque according to a difference between the torque command and the estimated output torque of the engine within a range from the lower limit torque to the upper limit torque.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a hybrid vehicle including an engine and an electric motor each coupled to a drive shaft.

Background Art

[0002] A conventionally known hybrid vehicle includes an engine coupled to a drive shaft, an electric motor coupled to the drive shaft, and a control device that controls the engine and the electric motor based on a required drive torque to be output to the drive shaft (see, for example, Patent Document 1). In this hybrid vehicle, the control device calculates an estimated output torque of the engine based on an accelerator opening, a vehicle speed, an atmospheric pressure, an outside air temperature, etc., and controls the electric motor to output a torque corresponding to a difference between the required drive torque and the estimated output torque of the engine.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] However, in the above-mentioned conventional hybrid vehicle, when the estimated output torque deviates from the actual output torque of the engine, the actual output torque of the electric motor deviates from the actually required motor torque, which may cause the acceleration / deceleration state of the hybrid vehicle to be unintended by the driver.

[0005] A main object of the present disclosure is to suppress deviation of the actual output torque of the electric motor from the actually required motor torque when the estimated output torque of the engine deviates from the actual output torque of the engine.

Means for Solving the Problem

[0006] The hybrid vehicle of this disclosure includes an engine connected to a drive shaft, an electric motor connected to the drive shaft, a battery that exchanges power with the electric motor, and a control device. Based on the operating state of the hybrid vehicle, the control device sets upper and lower torque limits for the electric motor so that the difference between a torque command indicating the torque to be output to the drive shaft and the actual torque output to the drive shaft is within an acceptable range. Furthermore, the control device controls the electric motor to output a torque corresponding to the difference between the torque command and the estimated output torque of the engine within the range from the lower torque limit to the upper torque limit. This makes it possible to suppress the actual output torque of the electric motor from deviating from the motor torque actually required when the estimated output torque of the engine deviates from the actual output torque of the engine. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic diagram illustrating the hybrid vehicle disclosed herein. [Figure 2] This flowchart shows an example of a routine performed by the control unit of the hybrid vehicle of this disclosure. [Figure 3] This is an explanatory diagram illustrating the control procedure for the electric motor in the hybrid vehicle of this disclosure. [Figure 4] This is an explanatory diagram illustrating the control procedure for the electric motor in the hybrid vehicle of this disclosure. [Figure 5] This is an explanatory diagram illustrating the control procedure for the electric motor in the hybrid vehicle of this disclosure. [Figure 6] This is a schematic diagram illustrating other hybrid vehicles in this disclosure. [Modes for carrying out the invention]

[0008] Next, with reference to the drawings, embodiments for carrying out the invention of this disclosure will be described.

[0009] Figure 1 is a schematic diagram showing the hybrid vehicle 1 of this disclosure. The hybrid vehicle 1 shown in the figure includes an engine (internal combustion engine) 2, a motor generator (electric motor) MG, a transmission 3, a clutch K0 and WSC, a battery (energy storage device) 4, a power control unit (hereinafter referred to as "PCU") 5 that drives the motor generator MG, and hydraulic control units 6 and 7. Furthermore, the hybrid vehicle 1 includes an engine electronic control unit (hereinafter referred to as "EGECU") 20 that controls the engine 2, a transmission electronic control unit (hereinafter referred to as "TMECU") 30 that controls the transmission 3, a motor electronic control unit (hereinafter referred to as "MGECU") 50 that controls the PCU 5, and a hybrid electronic control unit (hereinafter referred to as "HVECU") 100. The HVECU 100 exchanges information with the EGECU 20, TMECU 30 and MGECU 50 to comprehensively control the hybrid vehicle 1.

[0010] Engine 2 is a multi-cylinder gasoline engine (e.g., a V6 engine) that converts the reciprocating motion of pistons resulting from the combustion of a mixture of gasoline (hydrocarbon fuel) and air in multiple combustion chambers (cylinders) into rotational motion of a crankshaft (output shaft) CS. Engine 2 includes an electronically controlled throttle valve, multiple intake valves and exhaust valves, a variable valve timing mechanism, multiple fuel injectors, multiple spark plugs, an exhaust gas purification device, a turbocharger, and other superchargers (all not shown). The crankshaft CS of engine 2 is connected to the input member of a damper mechanism D (e.g., a flywheel damper). However, engine 2 may also be a diesel engine or an LPG engine, etc.

[0011] The motor-generator MG is a synchronous regenerative motor (three-phase AC motor) that includes a rotor with embedded permanent magnets and a stator around which three-phase coils are wound, and exchanges power with the battery 4 via the PCU 5. The motor-generator MG operates as an electric motor that generates driving torque when powered by the battery 4, and also outputs regenerative braking torque when the hybrid vehicle 1 is braked. In addition, the motor-generator MG also operates as a generator that generates electricity using at least a portion of the power from the engine 2 under load. As shown in Figure 1, the rotor of the motor-generator MG is fixed to the rotor shaft RS.

[0012] The transmission 3 is a multi-speed transmission, for example, a 4-speed to 10-speed transmission, including an input shaft 3i as a drive shaft, an output shaft 3o, multiple planetary gears, and multiple clutches and brakes (shifting engagement elements) for each. The transmission 3 shifts the power transmitted to the input shaft 3i in multiple stages and outputs it from the output shaft 3o to the left and right wheels (rear wheels) W via the differential gear DF ​​and axle VS. The clutches and brakes of the transmission 3 are hydraulic engagement elements driven by hydraulic pressure supplied from the hydraulic control device 6.

[0013] Clutch K0 connects the output member of damper mechanism D, i.e., the crankshaft CS of engine 2, to the rotor shaft RS, i.e., the rotor of motor generator MG, and also disengages the connection between them. When clutch K0 is engaged, engine 2 (crankshaft CS) is connected to motor generator MG via clutch K0. Clutch WSC connects the rotor shaft RS, i.e., the rotor of motor generator MG, to the input shaft 3i of transmission 3, and also disengages the connection between them. When clutch WSC is engaged, motor generator MG is connected to transmission 3 via clutch WSC. In other words, engine 2 is connected to the left and right wheels W via damper mechanism D, clutch K0, rotor shaft RS (motor generator MG), clutch WSC, transmission 3, differential gear DF, etc. In this embodiment, clutch K0 and WSC are, for example, normally open multi-plate hydraulic clutches driven by hydraulic pressure supplied from a hydraulic control device 7 different from the hydraulic control device 6. Clutch K0 and WSC may be located inside the rotor of motor generator MG.

[0014] Battery 4 is, for example, a lithium-ion secondary battery or nickel-metal hydride secondary battery having a rated output voltage of approximately 200-800V. However, battery 4 may also be a capacitor, or may include both a secondary battery and a capacitor. PCU 5 includes an inverter that drives the motor generator MG, a boost converter, a DC / DC converter, etc. (all not shown), and is connected to battery 4 via the system main relay SMR. The inverter includes, for example, six transistors as switching elements and six diodes connected in parallel to these transistors in the reverse direction. The boost converter boosts the voltage from battery 4 and supplies it to the inverter, and also steps down the voltage from the inverter and supplies it to battery 4. The DC / DC converter steps down the power from battery 4 or the inverter and supplies it to an auxiliary battery and various auxiliary equipment, etc. (all not shown).

[0015] The hydraulic control devices 6 and 7 each include a valve body with multiple oil passages, multiple regulator valves, multiple linear solenoid valves, etc. The hydraulic control device 6 regulates the hydraulic fluid (hydraulic pressure) from an electric oil pump (not shown) and supplies it to the clutch and brake of the transmission 3. The hydraulic control device 7 regulates the hydraulic fluid (hydraulic pressure) from the electric oil pump and supplies it to the clutch K0 and WSC. However, the clutch and brake of the transmission 3, clutch K0 and WSC may be driven by a single hydraulic control device.

[0016] The EGECU20, which controls engine 2, includes a microcomputer with a CPU, ROM, RAM, input / output interfaces, etc. (not shown), various drive circuits, various logic ICs, etc. The EGECU20 also acquires detection values ​​from various sensors (all not shown), such as a crank angle sensor, airflow meter, throttle opening sensor, air-fuel ratio sensor, water temperature sensor, and accelerator pedal position sensor, and receives command signals from the HVECU100. Furthermore, the EGECU20 calculates the rotational speed Ne of engine 2 (crankshaft CS) based on the detection value of the crank angle sensor, and calculates the load ratio KL based on the rotational speed Ne of engine 2 and the intake air volume detected by the airflow meter. The EGECU20 also calculates (estimates) the estimated output torque Teest of engine 2 based on the intake air volume, ignition timing, etc., using a well-known estimation method. The EGECU20 then controls the throttle valve, variable valve timing mechanism, fuel injector, spark plug, etc., based on detected values ​​from various sensors, calculated values ​​such as rotational speed Ne, and command signals from the HVECU100.

[0017] The TMECU30 includes a microcomputer with a CPU, ROM, RAM, input / output interfaces, etc. (not shown), various drive circuits, various logic ICs, etc. The TMECU30 also acquires detection values ​​from various sensors (all not shown), such as a shift position sensor, an accelerator pedal position sensor, an input rotation speed sensor that detects the rotation speed of the input shaft 3i, an output rotation speed sensor that detects the rotation speed of the output shaft 3o, and a vehicle speed sensor, and receives command signals from the HVECU100. The TMECU30 controls the transmission 3, or hydraulic control device 6, based on the detection values ​​from the various sensors and command signals from the HVECU100.

[0018] The MGECU50 includes a microcomputer with a CPU, ROM, RAM, input / output interfaces, etc. (not shown), various drive circuits, various logic ICs, etc. The MGECU50 acquires the pre-boost and post-boost voltages of the boost converter, the rotational position of the rotor (rotor shaft RS) of the motor generator MG detected by a rotational position sensor (resolver) (not shown), the phase current applied to the motor generator MG, etc., and also receives command signals from the HVECU100. The MGECU50 switches and controls the inverter and boost converter based on these detected values ​​and command signals from the HVECU100.

[0019] The HVECU 100 includes a microcomputer having a CPU, ROM, RAM, input / output interface, etc. (not shown), various drive circuits, various logic ICs, etc. The HVECU 100 receives a signal from a start switch (IG switch), an accelerator opening Acc (depression amount of an accelerator pedal) detected by an accelerator pedal position sensor, a vehicle speed V detected by a vehicle speed sensor, a gear position γ of a transmission 3 corresponding to the accelerator opening Acc and the vehicle speed V, a rotation speed Nm of a motor generator MG from the MGECU 50, and the like. Further, the HVECU 100 acquires, from a power management device (power management ECU) not shown, the SOC of the battery 4 calculated by the power management device, a target charge / discharge power Pb* based on the SOC, an allowable charge power Win, an allowable discharge power Wout, and the like. Based on these pieces of information, the HVECU 100 sets a torque command Te* for the engine 2, a torque command value Tm* for the motor generator MG, command values for the transmission 3 (hydraulic control device 6), and the like, and controls the clutch K0 and WSC, that is, the hydraulic control device 7.

[0020] The travel modes of the hybrid vehicle 1 configured as described above include an EV travel mode and an HEV travel mode. The EV travel mode is a mode in which the hybrid vehicle 1 travels while releasing the clutch K0 and fully or slip-engaging the clutch WSC. The HEV travel mode is a mode in which the hybrid vehicle 1 travels while fully or slip-engaging both the clutch K0 and WSC and operating the engine 2.

[0021] During traveling of the hybrid vehicle 1, the HVECU 100 sets, based on the accelerator opening Acc and the vehicle speed V, the required torque Tout that is required by the driver to be output to the output shaft 3o of the transmission 3 for causing the hybrid vehicle 1 to travel. Further, the HVECU 100 sets a value obtained by dividing the required torque Tout by the gear ratio (the rotation speed ratio between the input shaft 3i and the output shaft 3o) at the gear stage γ of the transmission 3, as the required torque Tireq that is required by the driver to be output to the input shaft 3i of the transmission 3. Then, the HVECU 100 performs gradual change processing such as smoothing processing and rate processing on the required torque Tireq as necessary, and sets the required torque Tireq or the value obtained by the gradual change processing as the torque command Ti* indicating the torque to be output to the input shaft 3i.

[0022] After setting the torque command Ti*, the HVECU 100 sets a torque command Te* for the engine 2 (Te*=0 in the EV traveling mode) and a torque command Tm* for the motor generator MG such that the battery 4 is charged or discharged with a target charge / discharge power Pb* that is separately set based on the SOC or the like, and a torque corresponding to the torque command Ti* is output to the input shaft 3i of the transmission 3. Further, the HVECU 100 transmits the torque command Te* for the engine 2 to the EGECU 20, and transmits the torque command Tm* for the motor generator MG to the MGECU 50. The EGECU 20 executes intake air amount control, fuel injection control, ignition timing control and the like of the engine 2 based on the received torque command Te*. The MGECU 50 performs switching control on an inverter or the like of the PCU 5 based on the received torque command Tm*.

[0023] Next, a control procedure for the motor generator MG while the hybrid vehicle 1 is traveling in the HEV traveling mode will be described with reference to FIGS. 2 to 5.

[0024] Figure 2 is a flowchart showing an example of a routine that is repeatedly executed by the HVECU 100 at predetermined time intervals (minute intervals) when the hybrid vehicle 1 is driving in HEV driving mode. When the execution timing of the routine in Figure 2 arrives, the HVECU 100 acquires information necessary for controlling the motor generator MG (step S100). The information acquired in step S100 includes accelerator opening Acc, vehicle speed V, transmission γ of the transmission 3, requested torque Tireq according to the driver's request, torque commands Ti*,Te*, requested regenerative braking torque Trereq, and estimated output torque Teest of the engine 2.

[0025] The required regenerative braking torque (Trreq) is set separately according to the pressure applied to the brake pedal by the driver of the hybrid vehicle 1. The required regenerative braking torque (Trreq) is obtained by multiplying the motor generator MG's share of the required braking force by a predetermined conversion coefficient. When the driver does not press the brake pedal, the required regenerative braking torque (Trreq) is zero. The estimated output torque (Teest) is calculated separately by the EGECU 20 as described above. The estimated output torque (Teest) includes the estimated drive torque output from engine 2, as well as the engine brake torque (friction torque) output from engine 2.

[0026] After processing in step S100, the HVECU100 calculates the charge / discharge torque Tcd by subtracting the torque command Te* from the required torque Tireq (step S110). The charge / discharge torque Tcd is the torque output to the input shaft 3i in conjunction with the charging or discharging of the battery 4. That is, if the sign of the charge / discharge torque Tcd is positive, the charge / discharge torque Tcd is the driving torque output to the input shaft 3i in conjunction with the discharge of the battery 4. If the sign of the charge / discharge torque Tcd is negative, the charge / discharge torque Tcd is the regenerative torque output to the input shaft 3i in conjunction with the charging of the battery 4.

[0027] Furthermore, in step S120, the HVECU 100 sets the acceleration quality management torque (hereinafter referred to as "acceleration QM torque") Tqma based on the vehicle speed V and the gear position γ of the transmission 3 acquired in step S100. The acceleration QM torque Tqma is the maximum torque (positive value) that, when the acceleration QM torque Tqma is output to the input shaft 3i of the transmission 3 in addition to the torque corresponding to the torque command Ti* under predetermined preconditions, can bring the acceleration state of the hybrid vehicle 1 within the range of quality management at the Automotive Safety Integrity Level (ASIL). In step S120, the HVECU 100 acquires the acceleration QM torque Tqma corresponding to the vehicle speed V and gear position γ acquired in step S100 from a pre-created acceleration QM torque setting map (not shown). The acceleration QM torque setting map is pre-adjusted through experiments and analyses based on the specifications of the hybrid vehicle 1, so as to define the correlation between the vehicle speed V, the gear stage γ of the transmission 3 (the gear ratio at that gear stage γ), and the acceleration QM torque Tqma.

[0028] Next, the HVECU100 calculates the upper limit torque Tamax of acceleration suppression for the motor generator MG based on the acceleration QM torque Tqma set in step S120, according to the following equation (1) (step S130). Furthermore, the HVECU100 calculates the lower limit torque Tamin of acceleration suppression for the motor generator MG based on the acceleration QM torque Tqma, according to the following equation (2) (step S140). The upper limit torque Tamax and the lower limit torque Tamin of acceleration suppression are used to suppress rapid acceleration of the hybrid vehicle 1 by keeping the difference between the torque command Ti*, which indicates the torque to be output to the input shaft 3i as a drive shaft, and the actual torque output to the input shaft 3i within an acceptable range based on quality management.

[0029] Tamax = Tqma - min(Tireq, 0) + max((Tireq - Ti*), 0) + Tcd …(1) Tamin = -Tqma + min(Tireq, 0) - max((Tireq - Ti*), 0) …(2)

[0030] The acceleration suppression upper limit torque Tamax is obtained by correcting the acceleration QM torque Tqma with the smaller of the required torque Tireq and zero, the larger of the difference between the required torque Tireq and the torque command Ti* and zero, and the charge / discharge torque Tcd. The acceleration suppression lower limit torque Tamin is obtained by correcting the inverse of the acceleration QM torque Tqma with the smaller of the required torque Tireq and zero, and the larger of the difference between the required torque Tireq and the torque command Ti* and zero. As can be seen from equations (1) and (2), the acceleration suppression lower limit torque Tamin is the inverse of the value obtained by subtracting (removing) the charge / discharge torque Tcd from the acceleration suppression upper limit torque Tamax.

[0031] Here, if the required torque Tireq is a negative value, the acceleration of the hybrid vehicle 1 decreases in accordance with the output of the required torque Tireq to the input shaft 3i. Therefore, in order to suppress the rapid acceleration of the hybrid vehicle 1, it is not necessary to limit the output of the required torque Tireq that reduces acceleration. For this reason, if the required torque Tireq is a negative value, as can be seen from equation (1), the absolute value of the required torque Tireq is added to the acceleration suppression upper limit torque Tamax. Furthermore, as can be seen from equation (2), the absolute value of the required torque Tireq is subtracted from the acceleration suppression lower limit torque Tamin.

[0032] Furthermore, annealing and other gradual change processing are intended to suppress the occurrence of shocks, etc. The limit amount of the torque command Ti* due to the gradual change processing is set so that even if torque equivalent to the limit amount is additionally output from the motor generator MG, there is no risk of the hybrid vehicle 1 accelerating or decelerating suddenly. For this reason, if the torque command Ti* is limited to a smaller (negative) value than the required torque Tireq due to the gradual change processing, the limit amount of the torque command Ti* due to the gradual change processing (=Tireq - Ti* (absolute value)) is added to the acceleration suppression upper limit torque Tamax, as shown in equation (1), in order to allow the output of torque equivalent to the limit amount of the torque command Ti* due to the gradual change processing. Furthermore, as shown in equation (2), this limit amount is subtracted from the acceleration suppression lower limit torque Tamin. In addition, the target charge / discharge power Pb* of the battery 4 is not affected by the estimation accuracy of the estimated output torque Teest of the engine 2. Therefore, the charge / discharge torque Tcd calculated in step S120 is added to the acceleration suppression upper limit torque Tamax to allow for the discharge of battery 4 and the charging of battery 4 with power generated by the motor generator MG.

[0033] Furthermore, in step S150, the HVECU 100 sets the deceleration quality management torque (hereinafter referred to as "deceleration QM torque") Tqmd based on the vehicle speed V and the gear position γ of the transmission 3 acquired in step S100. The deceleration QM torque Tqmd is the minimum torque (negative value) that, when the deceleration QM torque Tqmd is output to the input shaft 3i of the transmission 3 in addition to the torque corresponding to the torque command Ti* under predetermined preconditions, can bring the deceleration state of the hybrid vehicle 1 within the range of quality management at the level of automotive safety. In step S150, the HVECU 100 acquires the deceleration QM torque Tqmd corresponding to the vehicle speed V and gear position γ acquired in step S100 from a pre-created deceleration QM torque setting map (not shown). The deceleration QM torque setting map is pre-adjusted through experiments and analyses based on the specifications of the hybrid vehicle 1, so as to define the correlation between the vehicle speed V, the gear stage γ of the transmission 3 (the gear ratio at that gear stage γ), and the deceleration QM torque Tqmd.

[0034] Next, the HVECU100 calculates the upper limit torque Tdmax for deceleration suppression of the motor generator MG based on the deceleration QM torque Tqmd set in step S150 according to the following equation (3) (step S160). Furthermore, the HVECU100 calculates the lower limit torque Tdmin for deceleration suppression of the motor generator MG based on the said deceleration QM torque Tqmd according to the following equation (4) (step S170). The upper limit torque Tdmax and the lower limit torque Tdmin for deceleration suppression are set to keep the difference between the torque command Ti*, which indicates the torque to be output to the input shaft 3i as a drive shaft, and the actual torque output to the input shaft 3i within an acceptable range based on quality management, in order to suppress rapid deceleration of the hybrid vehicle 1.

[0035] Tdmax = -Tqmd + max(Tireq, 0) - min((Tireq - Ti*), 0) …(3) Tdmin = Tqmd - max(Tireq, 0) + min((Tireq - Ti*), 0) + Tcd + Trreq …(4)

[0036] The upper limit torque Tdmax for deceleration suppression is obtained by correcting the inverse of the deceleration QM torque Tqmd with the larger of the required torque Tireq and zero, and the smaller of the difference between the required torque Tireq and the torque command Ti* and zero. The lower limit torque Tdmin for deceleration suppression is obtained by correcting the deceleration QM torque Tqmd with the larger of the required torque Tireq and zero, the smaller of the difference between the required torque Tireq and the torque command Ti* and zero, the charge / discharge torque Tcd, and the required regenerative braking torque Trereq. As can be seen from equations (3) and (4), the upper limit torque Tdmax for deceleration suppression is the inverse of the value obtained by subtracting (excluding) the charge / discharge torque Tcd and the required regenerative braking torque Trereq from the lower limit torque Tdmin for deceleration suppression.

[0037] Here, if the required torque Tireq is a positive value, the deceleration of the hybrid vehicle 1 decreases in accordance with the output of the required torque Tireq to the input shaft 3i. Therefore, in order to suppress the rapid deceleration of the hybrid vehicle 1, it is not necessary to limit the output of the required torque Tireq that reduces the deceleration. For this reason, if the required torque Tireq is a positive value, the required torque Tireq (absolute value) is added to the deceleration suppression upper limit torque Tdmax, as shown in equation (3). Also, as shown in equation (4), the required torque Tireq (absolute value) is subtracted from the deceleration suppression lower limit torque Tdmin.

[0038] Furthermore, in order to allow the output of torque corresponding to the limit amount of the torque command Ti* due to the gradual change processing, if the torque command Ti* is limited to the positive side (larger) than the required torque Tireq by the gradual change processing, as can be seen from equation (3), the limit amount of the torque command Ti* due to the gradual change processing (=Tireq - Ti* (absolute value)) is added to the deceleration suppression upper limit torque Tdmax. Also, as can be seen from equation (4), this limit amount is subtracted from the deceleration suppression lower limit torque Tdmin. Furthermore, the charge / discharge torque Tcd calculated in step S120 is added to the deceleration suppression lower limit torque Tdmin in order to allow the discharge of battery 4 and the charging of battery 4 with power generated by motor generator MG. In addition, the required regenerative braking torque Trereq is not affected by the estimation accuracy of the estimated output torque Teest of engine 2. For this reason, the required regenerative braking torque Trereq obtained in step S100 is added to the deceleration suppression lower limit torque Tdmin in order to allow the output of regenerative braking torque by motor generator MG.

[0039] After processing in steps S130-S170, the HVECU100 sets the upper limit torque Tmax to the smaller of the acceleration suppression upper limit torque Tamax and the deceleration suppression upper limit torque Tdmax, and sets the lower limit torque Tmin to the larger of the acceleration suppression lower limit torque Tamin and the deceleration suppression lower limit torque Tdmin (step S180). Furthermore, the HVECU100 sets the torque command Tm* for the motor generator MG to the smaller of the larger of the value obtained by subtracting the estimated output torque Teest of engine 2 obtained in step S100 from the torque command Ti* and the lower limit torque Tmin, and the smaller of the upper limit torque Tmax (step S190). Then, the HVECU100 transmits the torque command Tm* to the MGECU50 (step S200), and temporarily terminates the routine in Figure 2. Based on the received torque command Tm*, the MGECU50 switches and controls the inverter, etc., of the PCU5.

[0040] As described above, the hybrid vehicle 1 includes an engine 2 connected to the input shaft 3i of the transmission 3 as a drive shaft via a clutch K0 and WSC, a motor generator MG connected to the input shaft 3i of the transmission 3 via a clutch WSC, a battery 4 that exchanges power with the motor generator MG, and control devices HVECU100 and MGECU50. Based on the operating state of the hybrid vehicle 1 (vehicle speed V and gear stage γ, etc.), the HVECU100 sets the upper limit torque Tmax and lower limit torque Tmin of the motor generator MG so that the difference between the torque command Ti* indicating the torque to be output to the input shaft 3i and the actual torque output to the input shaft 3i is within an acceptable range based on quality management (steps S100-S180 in Figure 2). Furthermore, the HVECU100 controls the motor generator MG in cooperation with the MGECU50 so that it outputs a torque corresponding to the difference between the torque command Ti* and the estimated output torque Teest of the engine 2 within the range from the lower limit torque Tmin to the upper limit torque Tmax (steps S190-S200).

[0041] As a result, in the hybrid vehicle 1, when the estimated output torque Teest of engine 2 deviates from the actual output torque of engine 2 (see dashed line in the figures), the torque command Tm* of the motor generator MG is limited by the upper torque Tmax or the lower torque Tmin, as shown in Figures 3, 4, and 5. This suppresses the actual output torque of the motor generator MG from deviating from the motor torque actually required, enabling the hybrid vehicle 1 to accelerate or decelerate appropriately.

[0042] Furthermore, the HVECU100 sets the acceleration QM torque Tqma and deceleration QM torque Tqmd based on the vehicle speed V and the gear stage γ of the transmission 3, so that the acceleration and deceleration states of the hybrid vehicle 1 are within the range of quality management in the automotive safety standards, and sets the upper limit torque Tmax and lower limit torque Tmin based on the acceleration QM torque Tqma and deceleration QM torque Tqmd (steps S100-S180). This eliminates the need to apply a development process compliant with functional safety standards to control using the estimated output torque Teest of the engine 2. As a result, the hybrid vehicle 1 can omit the monitoring process of the estimation accuracy of the estimated output torque Teest of the engine 2, which requires time and effort to properly adapt the abnormality judgment threshold, thereby reducing manufacturing costs. In other words, the technology of this disclosure is useful for hybrid vehicles 1 equipped with an engine 2 including a turbocharger, where the estimated output torque Teest tends to deviate from the actual output torque of the engine 2.

[0043] Furthermore, as shown in Figures 3 to 5, the HVECU100 corrects the upper limit torque Tmax and lower limit torque Tmin by the required torque Tireq, which the driver is required to output to the input shaft 3i of the transmission 3, in order to allow for a decrease in the acceleration and deceleration of the hybrid vehicle 1 (steps S120-S180). This adjusts the limit of the output torque of the motor generator MG according to the sign of the required torque Tireq, while keeping the acceleration and deceleration states of the hybrid vehicle 1 within the range of quality management in terms of automotive safety standards, thereby enabling the hybrid vehicle 1 to run according to the driver's demands.

[0044] Furthermore, when the torque command Ti* is subjected to a gradual change process, the HVECU100 corrects the upper limit torque Tmax and lower limit torque Tin by the limit amount of the torque command Ti* due to the gradual change process (=Tireq - Ti*) to allow for an increase in the acceleration and deceleration of the hybrid vehicle 1 (steps S120-S180). This prevents the output torque of the motor generator MG from being restricted more than necessary, enabling the hybrid vehicle 1 to run in accordance with the driver's demands.

[0045] Furthermore, the HVECU100 corrects the upper torque Tmax and lower torque Tmin to allow for the discharge of battery 4 and the charging of battery 4 with power generated by the motor generator MG (steps S120-S180). This makes it possible to maintain the State of Charge (SOC) of battery 4 appropriately while keeping the acceleration and deceleration states of the hybrid vehicle 1 within the range of quality management in terms of automotive safety standards.

[0046] In the hybrid vehicle 1, when an upshift or downshift of the transmission 3 is requested, the output torque of the motor-generator MG is decreased or increased to offset the moment of inertia associated with the upshift or downshift. This increase or decrease in the output torque of the motor-generator MG associated with the shift of the transmission 3 is not affected by the estimation accuracy of the estimated output torque Teest of the engine 2. Therefore, the above-mentioned upper limit torque Tmax and lower limit torque Tmin may be corrected by the increase or decrease in the output torque of the motor-generator MG associated with the shift of the transmission 3.

[0047] Furthermore, the hybrid vehicle 1 may be a four-wheel drive vehicle that includes a transfer or other motor generator for driving wheels other than the wheels W (front wheels), which are not shown. In addition, in the hybrid vehicle 1B shown in Figure 6, the motor generator MG may be controlled in the same manner as in the hybrid vehicle 1 described above.

[0048] In the hybrid vehicle 1B shown in Figure 6, the input shaft 3i of the transmission 3 is connected to the crankshaft CS of the engine 2 via a lock-up clutch LC, a damper mechanism D, and a torque converter TC. The output shaft 3o of the transmission 3 is connected (directly connected) to the rotor shaft RS fixed to the rotor of the motor generator MG, and is connected to the wheels W via the motor generator MG (rotor shaft RS) and a differential gear DF, etc. In such a hybrid vehicle 1B, by setting the upper limit torque Tmax and the lower limit torque Tmin as described above, it is possible to suppress the deviation of the actual output torque of the motor generator MG from the motor torque actually required. Furthermore, the hybrid vehicle 1B may also be a four-wheel drive vehicle that includes a transfer case or other motor generator for driving wheels other than the wheels W (front wheels) that are not shown.

[0049] The invention disclosed herein is not limited in any way to the embodiments described above, and it goes without saying that various modifications can be made within the scope of this disclosure. Furthermore, the embodiments described above are merely one specific form of the invention described in the summary section of the invention, and do not limit the elements of the invention described in the summary section of the invention. [Industrial applicability]

[0050] The invention disclosed herein can be used in industries such as the hybrid vehicle manufacturing industry. [Explanation of symbols]

[0051] 1,1B Hybrid vehicle, 2 Engine, 3 Transmission, 3i Input shaft, 3o Output shaft, 4 Battery, 5 Power control unit (PCU), 6,7 Hydraulic control unit, 20 Engine electronic control unit (EGECU), 30 Transmission electronic control unit (TMECU), 50 Motor electronic control unit (MGECU), 100 Hybrid electronic control unit (HVECU), KO,WSC Clutch, MG Motor generator.

Claims

1. In a hybrid vehicle including an engine connected to a drive shaft, an electric motor connected to the drive shaft, and a battery that exchanges power with the electric motor, A transmission connected to the drive shaft and transmitting power from the drive shaft to the wheels, A control device that sets the upper and lower torque limits of the electric motor so that the difference between a torque command indicating the torque to be output to the drive shaft and the actual torque output to the drive shaft is within an acceptable range, based on the driving state of the hybrid vehicle, and controls the electric motor to output a torque corresponding to the difference between the torque command and the estimated output torque of the engine within the range from the lower torque limit to the upper torque limit, Equipped with, The control device sets the upper and lower torque limits based on the vehicle speed and the gear shift of the transmission so that the acceleration and deceleration states of the hybrid vehicle are within the range of quality management in ASIL, which is the automotive safety standard. Hybrid vehicle.

2. In the hybrid vehicle described in claim 1, The control device corrects the upper and lower torque limits with the required torque that the driver is required to output to the drive shaft, so as to allow a reduction in the acceleration and deceleration of the hybrid vehicle.

3. In the hybrid vehicle described in claim 2, The control device corrects the upper limit torque and the lower limit torque of the torque command by the limit amount of the torque command due to the slow change processing, so as to allow an increase in the acceleration and deceleration of the hybrid vehicle when the torque command is subjected to slow change processing.

4. In the hybrid vehicle according to claim 2 or 3, The electric motor is capable of generating electricity using at least a portion of the power from the engine, A hybrid vehicle in which the control device corrects the upper limit torque and the lower limit torque to allow the discharge of the battery and the charging of the battery with power generated by the electric motor.

Images