Hybrid vehicle

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 connected to a drive shaft.

Background Art

[0002] Conventionally known hybrid vehicles include an engine connected to a drive shaft, an electric motor connected 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 the accelerator opening, vehicle speed, atmospheric pressure, outside air temperature, etc., and controls the electric motor to output a torque corresponding to the difference between the required drive torque and the estimated output torque of the engine.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above 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 may deviate from the motor torque actually required, and there is a risk that the acceleration / deceleration state of the hybrid vehicle may become unintended by the driver.

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

Means for Solving the Problems

[0006] The hybrid vehicle of the present 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. The control device sets the upper limit torque and the lower limit torque of the electric motor so that the difference between the torque command indicating the torque to be output to the drive shaft and the actual torque output to the drive shaft is within an allowable range based on the operating state of the hybrid vehicle. Further, the control device controls the electric motor to output torque according to the difference between the torque command and the estimated output torque of the engine within the range from the lower limit torque to the upper limit torque. 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 Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

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

[0009] FIG. 1 is a schematic configuration diagram showing a hybrid vehicle 1 of the present 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, clutches K0 and WSC, a battery (power storage device) 4, a power control unit (hereinafter referred to as "PCU") 5 that drives the motor generator MG, and hydraulic control devices 6 and 7. Further, 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] The engine 2 is a multi-cylinder gasoline engine (for example, a V-type 6-cylinder engine) that converts the reciprocating motion of a piston accompanying the combustion of a mixture of gasoline (hydrocarbon-based fuel) and air in a plurality of combustion chambers (cylinders) into the rotational motion of a crankshaft (output shaft) CS. The engine 2 includes an electronically controlled throttle valve, a plurality of intake valves and exhaust valves respectively, a variable valve mechanism, a plurality of fuel injection valves, a plurality of spark plugs, an exhaust gas purification device, a supercharger such as a turbocharger (all are not shown). The crankshaft CS of the engine 2 is connected to an input member of a damper mechanism D (for example, a flywheel damper). However, the engine 2 may be a diesel engine or an LPG engine, etc.

[0011] The motor generator MG is a synchronous generator motor (three-phase AC motor) including a rotor in which permanent magnets are embedded and a stator around which a three-phase coil is wound, and exchanges electric power with the battery 4 via the PCU 5. The motor generator MG operates as an electric motor that is driven by the electric power from the battery 4 to generate driving torque, and outputs regenerative braking torque during braking of the hybrid vehicle 1. Further, the motor generator MG also operates as a generator that generates electric power using at least part of the power from the engine 2 that is under load operation. As shown in FIG. 1, the rotor of the motor generator MG is fixed to the rotor shaft RS.

[0012] The transmission 3 is, for example, a four-speed to ten-speed multi-stage transmission including an input shaft 3i as a drive shaft, an output shaft 3o, a plurality of planetary gears, a plurality of clutches and brakes (shift engagement elements) respectively. 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 the axle VS. The clutches and brakes of the transmission 3 are hydraulic engagement elements that are driven by the hydraulic pressure supplied from the hydraulic control device 6.

[0013] Clutch K0 connects the output member of the damper mechanism D, i.e., the crankshaft CS of the engine 2, and the rotor shaft RS, i.e., the rotor of the motor generator MG, and releases the connection between the two. When clutch K0 engages, the engine 2 (crankshaft CS) is connected to the motor generator MG via the clutch K0. Clutch WSC connects the rotor shaft RS, i.e., the rotor of the motor generator MG, and the input shaft 3i of the transmission 3, and releases the connection between the two. When clutch WSC engages, the motor generator MG is connected to the transmission 3 via the clutch WSC. That is, the engine 2 is connected to the left and right wheels W via the damper mechanism D, clutch K0, rotor shaft RS (motor generator MG), clutch WSC, transmission 3, differential gear DF, etc. In the present embodiment, clutches 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. Clutches K0 and WSC may be arranged inside the rotor of the motor generator MG.

[0014] Battery 4 is, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery having a rated output voltage of about 200 - 800V. However, battery 4 may 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 a system main relay SMR. The inverter includes, for example, six transistors as switching elements and six diodes connected in parallel in the reverse direction to these transistors. 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 devices (all not shown).

[0015] The hydraulic control devices 6 and 7 each include a valve body in which a plurality of oil passages are formed, a plurality of regulator valves, a plurality of linear solenoid valves, and the like. The hydraulic control device 6 regulates the hydraulic oil (hydraulic pressure) from an electric oil pump (not shown) and supplies it to the clutches and brakes of the transmission 3. The hydraulic control device 7 regulates the hydraulic oil (hydraulic pressure) from the electric oil pump and supplies it to the clutches K0 and WSC. However, the clutches and brakes of the transmission 3, and the clutches K0 and WSC may be driven by a single hydraulic control device.

[0016] The EGECU 20 that controls the engine 2 includes a microcomputer having a CPU, ROM, RAM, input / output interfaces, etc. (not shown), various drive circuits, various logic ICs, and the like. Further, the EGECU 20 acquires the detection values of various sensors (all not shown) such as a crank angle sensor, an air flow meter, a throttle opening sensor, an air-fuel ratio sensor, a water temperature sensor, and an accelerator pedal position sensor, and receives a command signal from the HVECU 100. Furthermore, the EGECU 20 calculates the rotational speed Ne of the engine 2 (crankshaft CS) based on the detection value of the crank angle sensor, and calculates the load factor KL based on the rotational speed Ne of the engine 2 and the intake air amount detected by the air flow meter. In addition, the EGECU 20 calculates (estimates) the estimated output torque Teest of the engine 2 based on the intake air amount, ignition timing, etc. by a well-known estimation method. Then, the EGECU 20 controls the throttle valve, the variable valve mechanism, the fuel injection valve, the ignition plug, etc. based on the detection values of various sensors, the calculated values such as the rotational speed Ne, the command signal from the HVECU 100, etc.

[0017] TMECU 30 includes a microcomputer having a CPU, ROM, RAM, input / output interfaces, etc. (not shown), various drive circuits, various logic ICs, etc. Further, TMECU 30 acquires detection values of various sensors such as a shift position sensor, an accelerator pedal position sensor, an input rotation speed sensor for detecting the rotation speed of the input shaft 3i, an output rotation speed sensor for detecting the rotation speed of the output shaft 3o, and a vehicle speed sensor (all not shown), and receives a command signal etc. from HVECU 100. TMECU 30 controls the transmission 3, that is, the hydraulic control device 6, based on the detection values of the various sensors and the command signal etc. from HVECU 100.

[0018] MGECU 50 includes a microcomputer having a CPU, ROM, RAM, input / output interfaces, etc. (not shown), various drive circuits, various logic ICs, etc. MGECU 50 acquires the pre-boost voltage and the post-boost voltage of the boost converter, the rotational position of the rotor (rotor shaft RS) of the motor generator MG detected by a rotation position sensor (resolver) (not shown), the phase current applied to the motor generator MG, etc., and receives a command signal etc. from HVECU 100. MGECU 50 performs switching control of the inverter and the boost converter based on these detection values and the command signal etc. from HVECU 100.

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

[0020] The driving modes of the hybrid vehicle 1 configured as described above include an EV driving mode and an HEV driving mode. The EV driving mode is to drive the hybrid vehicle 1 while releasing the clutch K0 and fully engaging or slip-engaging the clutch WSC. Also, the HEV driving mode is to drive the hybrid vehicle 1 while fully engaging or slip-engaging both the clutch K0 and the WSC and operating the engine 2.

[0021] During the running of the hybrid vehicle 1, the HVECU 100 sets a required torque Tout that is required to be output by the driver to the output shaft 3o of the transmission 3 based on the accelerator opening Acc and the vehicle speed V. Further, the HVECU 100 sets a required torque Tireq that is required to be output by the driver to the input shaft 3i of the transmission 3 as a value obtained by dividing the required torque Tout by the gear ratio (rotation speed ratio between the input shaft 3i and the output shaft 3o) in the gear position γ of the transmission 3. Then, the HVECU 100 performs a slow change process such as smoothing processing or rate processing on the required torque Tireq as necessary, and sets the required torque Tireq or a value obtained by the slow change process as a 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 (in the EV running mode, Te* = 0) and a torque command Tm* for the motor generator MG so that the battery 4 is charged or discharged with a target charge / discharge power Pb* separately set based on the SOC, etc., and the 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, etc. of the engine 2 based on the received torque command Te*. The MGECU 50 performs switching control of the inverter, etc. of the PCU 5 based on the received torque command Tm*.

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

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

[0025] The required regenerative braking torque Trreq is separately set according to the depression of the brake pedal by the driver of the hybrid vehicle 1. The required regenerative braking torque Trreq is obtained by multiplying a predetermined conversion coefficient by the share of the motor generator MG with respect to the required braking force by the driver. When the brake pedal is not depressed by the driver, the required regenerative braking torque Trreq becomes zero. The estimated output torque Teest is separately calculated by the EGECU 20 as described above. The estimated output torque Teest includes, in addition to the estimated value of the driving torque output from the engine 2, the engine braking torque (friction torque) output from the engine 2.

[0026] After the process of step S100, the HVECU 100 subtracts the torque command Te* from the required torque Tireq to calculate the charge / discharge torque Tcd (step S110). The charge / discharge torque Tcd is the torque output to the input shaft 3i as the battery 4 is charged or discharged. That is, when 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 as the battery 4 is discharged. When 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 as the battery 4 is charged.

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

[0028] Subsequently, the HVECU 100 calculates the acceleration suppression upper limit torque Tamax of the motor generator MG based on the acceleration QM torque Tqma set in step S120 according to the following formula (1) (step S130). Furthermore, the HVECU 100 calculates the acceleration suppression lower limit torque Tamin of the motor generator MG based on the acceleration QM torque Tqma according to the following formula (2) (step S140). The acceleration suppression upper limit torque Tamax and the acceleration suppression lower limit torque Tamin are for suppressing the sudden acceleration of the hybrid vehicle 1 by keeping the difference between the torque command Ti* indicating the torque to be output to the input shaft 3i as the drive shaft and the actual torque output to the input shaft 3i within the allowable 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 charge / discharge torque Tcd, taking the smaller value between the required torque Tireq and zero, and the larger value between the difference between the required torque Tireq and the torque command Ti* and zero. The acceleration suppression lower limit torque Tamin is obtained by correcting the inverse of the acceleration QM torque Tqma, taking the smaller value between the required torque Tireq and zero, and the larger value between 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 (excluding) the charge / discharge torque Tcd from the acceleration suppression upper limit torque Tamax.

[0031] Here, when the required torque Tireq is a negative value, the acceleration of the hybrid vehicle 1 decreases in response to the output of the required torque Tireq to the input shaft 3i. Therefore, in order to suppress the sudden acceleration of the hybrid vehicle 1, it is not necessary to limit the output of the required torque Tireq that decreases the acceleration. For this reason, when 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] Also, the slow change process such as the namashi process is for suppressing the occurrence of shocks or the like, and the limiting amount of the torque command Ti* by the slow change process is set so that even if the torque corresponding to the limiting amount is additionally output from the motor generator MG, there is no possibility that the hybrid vehicle 1 suddenly accelerates or decelerates. For this reason, when the torque command Ti* is limited to be smaller (on the negative side) than the required torque Tireq by the slow change process, in order to allow the output of the torque corresponding to the limiting amount of the torque command Ti* by the slow change process, as shown in Equation (1), the limiting amount of the torque command Ti* by the slow change process (= absolute value of Tireq - Ti*) is added to the acceleration suppression upper limit torque Tamax. Further, as shown in Equation (2), the limiting amount is subtracted from the acceleration suppression lower limit torque Tamin. Also, 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. For this reason, the charge / discharge torque Tcd calculated in step S120 is added to the acceleration suppression upper limit torque Tamax so as to allow the discharge of the battery 4 and the charging of the battery 4 by the power generated by the motor generator MG.

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

[0034] Next, the HVECU 100 calculates the deceleration suppression upper limit torque Tdmax of the motor generator MG based on the deceleration QM torque Tqmd set in step S150 according to the following equation (3) (step S160). Further, the HVECU 100 calculates the deceleration suppression lower limit torque Tdmin of the motor generator MG based on the deceleration QM torque Tqmd according to the following equation (4) (step S170). The deceleration suppression upper limit torque Tdmax and the deceleration suppression lower limit torque Tdmin are for suppressing a rapid deceleration of the hybrid vehicle 1 by keeping the difference between the torque command Ti* indicating the torque to be output to the input shaft 3i as the drive shaft and the actual torque output to the input shaft 3i within an allowable range based on quality management.

[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 deceleration suppression upper limit torque Tdmax 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 deceleration suppression lower limit torque Tdmin 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 regeneration braking torque Trreq. As can be seen from equations (3) and (4), the deceleration suppression upper limit torque Tdmax is the inverse of the value obtained by subtracting (excluding) the charge / discharge torque Tcd and the required regeneration braking torque Trreq from the deceleration suppression lower limit torque Tdmin.

[0037] Here, when the required torque Tireq is a positive value, the deceleration of the hybrid vehicle 1 decreases in response to the output of the required torque Tireq to the input shaft 3i. Therefore, in order to suppress the sudden deceleration of the hybrid vehicle 1, it is not necessary to limit the output of the required torque Tireq that decreases the deceleration. For this reason, when the required torque Tireq is a positive value, as shown in Equation (3), the required torque Tireq (absolute value) is added to the deceleration suppression upper limit torque Tdmax. 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 the torque corresponding to the limited amount of the torque command Ti* by the slow change process, when the torque command Ti* is limited to the positive side (larger) than the required torque Tireq by the slow change process, as can be seen from Equation (3), the limited amount of the torque command Ti* by the slow change process (= Tireq - Ti* (absolute value)) is added to the deceleration suppression upper limit torque Tdmax. Also, as can be seen from Equation (4), the limited 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 so as to allow the discharge of the battery 4 and the charging of the battery 4 by the electric power generated by the motor generator MG. Also, the required regenerative braking torque Trreq is not affected by the estimation accuracy of the estimated output torque Teest of the engine 2. For this reason, the required regenerative braking torque Trreq acquired in step S100 is added to the deceleration suppression lower limit torque Tdmin so as to allow the output of the regenerative braking torque by the motor generator MG.

[0039] After the processes of steps S130 - S170, the HVECU 100 sets the smaller value of the acceleration suppression upper limit torque Tamax and the deceleration suppression upper limit torque Tdmax as the upper limit torque Tmax, and sets the larger value of the acceleration suppression lower limit torque Tamin and the deceleration suppression lower limit torque Tdmin as the lower limit torque Tmin (step S180). Further, the HVECU 100 sets the larger value between the value obtained by subtracting the estimated output torque Teest of the engine 2 acquired in step S100 from the torque command Ti* and the lower limit torque Tmin, and the smaller value between this and the upper limit torque Tmax as the torque command Tm* for the motor generator MG (step S190). Then, the HVECU 100 transmits the torque command Tm* to the MGECU 50 (step S200) and once terminates the routine of FIG. 2. The MGECU 50 performs switching control of the inverter etc. of the PCU 5 based on the received torque command Tm*.

[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 a WSC, a motor generator MG connected to the input shaft 3i of the transmission 3 via the clutch WSC, a battery 4 that exchanges power with the motor generator MG, and an HVECU 100 and an MGECU 50 as control devices. The HVECU 100 sets the upper limit torque Tmax and the 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 the allowable range based on quality management according to the operating state (vehicle speed V, gear stage γ, etc.) of the hybrid vehicle 1 (steps S100 - S180 in FIG. 2). Further, the HVECU 100 controls the motor generator MG in cooperation with the MGECU 50 so as to output 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, as shown in FIGS. 3, 4, and 5, when the estimated output torque Teest of the engine 2 deviates from the actual output torque of the engine 2 (see the two-dot chain line in the figure), the torque command Tm* of the motor generator MG is limited by the upper limit torque Tmax or the lower limit torque Tmin. This suppresses the deviation of the actual output torque of the motor generator MG from the motor torque actually required, enabling the hybrid vehicle 1 to accelerate or decelerate properly.

[0042] Also, the HVECU 100 sets the acceleration QM torque Tqma and the deceleration QM torque Tqmd based on the vehicle speed V and the gear position γ of the transmission 3 so that the acceleration state and the deceleration state of the hybrid vehicle 1 are within the range of quality management at the automobile safety level, and sets the upper limit torque Tmax and the lower limit torque Tmin based on the acceleration QM torque Tqma and the deceleration QM torque Tqmd (steps S100 - S180). This eliminates the need to apply a development process compliant with the functional safety standard to the 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 effort to properly conform to the abnormality determination threshold, and reduces the manufacturing cost. That is, the technology of the present disclosure is useful for the hybrid vehicle 1 equipped with the engine 2 including a supercharger in which the estimated output torque Teest tends to deviate from the actual output torque of the engine 2.

[0043] Furthermore, as shown in FIGS. 3 to 5, the HVECU 100 corrects the upper limit torque Tmax and the lower limit torque Tmin with the required torque Tireq that is required to be output to the input shaft 3i of the transmission 3 by the driver so as to allow a decrease in the acceleration and deceleration of the hybrid vehicle 1 (steps S120 - S180). This enables the hybrid vehicle 1 to travel according to the driver's request by adjusting the limit of the output torque of the motor generator MG according to the sign of the required torque Tireq while keeping the acceleration state and the deceleration state of the hybrid vehicle 1 within the range of quality management at the automobile safety level.

[0044] Also, when a slow change process is applied to the torque command Ti*, the HVECU 100 corrects the upper limit torque Tmax and the lower limit torque Tin with the limited amount of the torque command Ti* (= Tireq - Ti*) by the slow change process so as to allow an increase in the acceleration and deceleration of the hybrid vehicle 1 (steps S120 - S180). This suppresses the output torque of the motor generator MG from being restricted more than necessary, and enables the hybrid vehicle 1 to travel according to the driver's request.

[0045] Furthermore, the HVECU 100 corrects the upper limit torque Tmax and the lower limit torque Tmin so as to allow the discharge of the battery 4 and the charging of the battery 4 with the electric power generated by the motor generator MG (steps S120 - S180). This makes it possible to keep the SOC of the battery 4 appropriate while keeping the acceleration state and the deceleration state of the hybrid vehicle 1 within the range of quality management at the automobile safety level.

[0046] In the hybrid vehicle 1, when an upshift or a downshift of the transmission 3 is requested, the output torque of the motor generator MG is decreased or increased to cancel the moment of inertia associated with the upshift or the downshift. The increase or decrease in the output torque of the motor generator MG associated with such a 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-described 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] Also, the hybrid vehicle 1 may be a four-wheel drive vehicle including a transfer or another motor generator for driving wheels (front wheels) not shown other than the wheels W. Further, in the hybrid vehicle 1B shown in FIG. 6, the motor generator MG may be controlled in the same manner as the above-described hybrid vehicle 1.

[0048] In the hybrid vehicle 1B shown in FIG. 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. Further, the output shaft 3o of the transmission 3 is connected (directly connected) to a 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 or the like. Also in such a hybrid vehicle 1B, by setting the upper limit torque Tmax and the lower limit torque Tmin as described above, it becomes possible to suppress the actual output torque of the motor generator MG from deviating from the motor torque actually required. Further, the hybrid vehicle 1B may also be a four-wheel drive vehicle including a transfer or another motor generator for driving wheels (front wheels) not shown other than the wheels W.

[0049] The invention of the present disclosure is not limited to the above-described embodiments at all, and it goes without saying that various changes can be made within the scope of the disclosure. Further, the above-described embodiments are merely specific forms 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 of the present disclosure can be used in the manufacturing industry of hybrid vehicles and the like.

Explanation of Reference Numerals

[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 control device is provided that sets an upper limit torque and a lower limit torque of the electric motor so that a difference between a torque command indicating torque to be output to the drive shaft and an actual torque output to the drive shaft is within an allowable range based on an operating state of the hybrid vehicle, and controls the electric motor to output torque corresponding to a difference between the torque command and an estimated output torque of the engine within a range from the lower limit torque to the upper limit torque.

2. The hybrid vehicle according to Claim 1, further comprising a transmission connected to the drive shaft and transmitting power from the drive shaft to wheels, wherein the control device sets the upper limit torque and the lower limit torque based on a vehicle speed and a gear position of the transmission so that an acceleration state and a deceleration state of the hybrid vehicle are within a range of quality management at an automobile safety level.

3. The hybrid vehicle according to Claim 2, wherein the control device corrects the upper limit torque and the lower limit torque with a required torque required to be output to the drive shaft by a driver so as to allow a decrease in acceleration and deceleration of the hybrid vehicle.

4. The hybrid vehicle according to Claim 3, wherein the control device corrects the upper limit torque and the lower limit torque with a limited amount of the torque command by the slow change process so as to allow an increase in acceleration and deceleration of the hybrid vehicle when the slow change process is applied to the torque command.

5. The hybrid vehicle according to Claim 3 or 4, wherein the electric motor is capable of generating electricity using at least a part of power from the engine, and the control device corrects the upper limit torque and the lower limit torque so as to allow discharging of the battery and charging of the battery with electric power generated by the electric motor.

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