Four-wheel drive hybrid vehicle

Abstract

To provide a four-wheel drive hybrid vehicle that can suppress occurrence of hesitation on the hybrid vehicle, when starting an engine during EV traveling.SOLUTION: A four-wheel drive hybrid vehicle, in which a generator starts an engine by supplying electric power to the generator from a drive battery, comprises a travel control device that changes an output allocation of total output to a front driving system and a rear driving system to thereby increase total efficiency of a driving system constituted of the front driving system including a front motor and a front transaxle as well as the rear driving system including a rear motor and a rear transaxle, when starting the engine, during EV traveling in which electric power is supplied to the front motor and the rear motor from the drive battery, in a state where the engine is stopped.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to four-wheel drive hybrid vehicles. [Background technology]

[0002] There is a widely known four-wheel drive hybrid vehicle that includes an engine, a generator driven by the engine, a drive motor that stores electricity generated by the generator, a front motor that receives electricity from the generator or a drive battery, a rear transaxle that is provided between the front motor and the front wheels and transmits the drive force of the front motor to the front wheels, and a rear transaxle that is provided between the rear motor and the rear wheels and transmits the drive force of the rear motor to the rear wheels. In such a hybrid vehicle, the generator starts the engine by supplying electricity from the drive battery to the generator (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-93777 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the engine is started during EV driving in which electricity is supplied from the drive battery to the front motor and rear motor with the engine stopped, electricity is supplied from the drive battery to the generator, so the electricity supplied to the front motor and rear motor decreases, causing hesitation in the hybrid vehicle.

[0005] In view of the above circumstances, an object of at least one embodiment of the present invention is to provide a four-wheel drive hybrid vehicle that can suppress hesitation that occurs in the hybrid vehicle when the engine is started during EV running. [Means for solving the problem]

[0006] (1) A four-wheel drive hybrid vehicle according to at least one embodiment of the present invention comprises an engine, a generator driven by the engine, a drive battery that stores electricity generated by the generator, a front motor and a rear motor that are supplied with electricity from the generator or the drive battery, a front transaxle that is provided between the front motor and front wheels and transmits the driving force of the front motor to the front wheels, and a rear transaxle that is provided between the rear motor and the rear wheels and transmits the driving force of the rear motor to the rear wheels, and the generator starts the engine by supplying electricity from the drive battery to the generator.The vehicle is further equipped with a driving control device that changes the output distribution of overall output to the front drive system and the rear drive system so that the overall efficiency of the drive system composed of a front drive system including the front motor and the front transaxle, and a rear drive system including the rear motor and the rear transaxle is increased when the engine is started during EV driving in which electricity is supplied from the drive battery to the front motor and the rear motor with the engine stopped.

[0007] According to the above configuration (1), when the engine is started during EV driving, the overall efficiency of the drive system is increased, so that hesitation occurring in the hybrid vehicle can be suppressed.

[0008] (2) In some embodiments, in the configuration of (1) above, the driving control device includes an overall efficiency memory unit that stores an overall efficiency associated with the rotation speed of the front wheels and the output distributed to the front drive system, as well as the rotation speed of the rear wheels and the output distributed to the rear drive system, an output distribution determination unit that determines the output distributed to the front drive system and the output distributed to the rear drive system based on the rotation speed of the front wheels and the rotation speed of the rear wheels, and the overall efficiency, and an output change unit that changes the output distribution of the overall output to the front drive system and the rear drive system so as to increase the overall efficiency.

[0009] According to the above configuration (2), the output change unit changes the output distribution of the overall output to the front drive system and the rear drive system so that the overall efficiency of the drive system composed of the front drive system and the rear drive system is increased. This increases the overall efficiency of the drive system and suppresses hesitation that occurs in the hybrid vehicle.

[0010] (3) In some embodiments, in the configuration of (2) above, the driving control device includes a front drive system efficiency memory unit that stores an efficiency of the front drive system associated with the rotation speed of the front wheels and the output distributed to the front drive system, a rear drive system efficiency memory unit that stores an efficiency of the rear drive system associated with the rotation speed of the rear wheels and the output distributed to the rear drive system, a front drive system efficiency specification unit that specifies the efficiency of the front drive system based on the rotation speed of the front wheels and the output distributed to the front drive system, a rear drive system efficiency specification unit that specifies the efficiency of the rear drive system based on the rotation speed of the rear wheels and the output distributed to the rear drive system, and an overall efficiency calculation unit that calculates the overall efficiency based on the output distributed to the front drive system and the output distributed to the rear drive system, as well as the efficiency of the front drive system and the efficiency of the rear drive system, and the overall efficiency memory unit stores the overall efficiency calculated by the overall efficiency calculation unit.

[0011] According to the above configuration (3), the efficiency of the front drive system is determined based on the rotation speed of the front wheels and the power distributed to the front drive system, and the efficiency of the rear drive system is determined based on the rotation speed of the rear wheels and the power distributed to the rear drive system. Then, the overall efficiency of the drive system consisting of the front drive system and the rear drive system is calculated based on the power distributed to the front drive system and the power distributed to the rear drive system, and the efficiency of the front drive system and the efficiency of the rear drive system, and is stored in the overall efficiency storage unit.

[0012] (4) In some embodiments, in the configuration of (2) above, the output change unit has a torque change unit that changes the torque of the front motor and the torque of the rear motor.

[0013] According to the above configuration (4), the torque change unit changes the torque of the front motor and the torque of the rear motor, thereby making it possible to change the output distribution of the overall output to the front drivetrain and the rear drivetrain. Effect of the Invention

[0014] According to at least one embodiment of the present invention, it is possible to suppress hesitation that occurs in a hybrid vehicle when the engine is started during EV running. [Brief description of the drawings]

[0015] [Figure 1] 1 is a diagram illustrating a schematic mechanical configuration of a hybrid vehicle according to an embodiment; [Diagram 2] 1 is a block diagram illustrating a control configuration of a hybrid vehicle according to an embodiment of the present invention; [Diagram 3] 3 is a block diagram illustrating a control configuration of the driving control device illustrated in FIG. 2. [Figure 4] FIG. 13 is a diagram showing the efficiency associated with each of the power distributions of the total power distributed to the front drivetrain and the rear drivetrain, and the total efficiency. [Figure 5-1] FIG. 4 is a diagram showing the rotation speed and torque of the front wheels and the power distributed to the front drive system. [Figure 5-2] FIG. 11 is a diagram showing the rotation speed and torque of the front wheels and the efficiency of the front drive system. [Figure 6-1] FIG. 4 is a diagram showing the rotation speed and torque of the rear wheels and the power distributed to the rear drive train. [Figure 6-2] FIG. 11 is a diagram showing the rotation speed and torque of the rear wheels and the efficiency of the rear drive system. [Figure 7] 4 is a flowchart illustrating a control operation of the hybrid vehicle according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as the embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention.

[0017] [Hybrid vehicle] The hybrid vehicle according to the embodiment is a plug-in hybrid vehicle (PHEV) that can be charged (external charging) from an external device (e.g., a quick charger) while parked, and can supply power (external power supply) to the outside (e.g., an ordinary household) while parked, but is not limited to this.

[0018] [Hybrid vehicle mechanical configuration] As shown in FIG. 1, the hybrid vehicle 1 according to the embodiment is a four-wheel drive hybrid vehicle and includes an engine 11, a generator 12 driven by the engine 11, a drive battery 13 that stores electricity generated by the generator 12, a front motor 14 and a rear motor 15 that are supplied with electricity from the generator 12 or the drive battery 13, a front transaxle 17 provided between the front motor 14 and front wheels 16 and that transmits the drive force of the front motor 14 to the front wheels 16, and a rear transaxle 19 provided between the rear motor 15 and rear wheels 18 and that transmits the drive force of the rear motor 15 to the rear wheels 18.

[0019] A fuel pipe 20 is connected to the engine 11, and fuel is supplied to the engine 11 from a fuel tank 21 provided behind the drive battery 13 through the fuel pipe 20. The generator 12 and the front motor 14 are electrically connected to a front power drive unit (FPDU) 31. The FPDU 31 has a generator control unit (GCU) and a front motor control unit (FMCU) built in. The GCU is configured to control the generator 12 and rectify the generated electricity from AC to DC. The FMCU is configured to control the front motor 14 and convert the electricity supplied from the drive battery 13 from DC to AC and convert the electricity regenerated by the front motor 14 from AC to DC. The rear motor 15 is electrically connected to a rear motor control unit (RMCU) 32. The RMCU 32 is configured to control the rear motor 15 and convert the electricity supplied from the drive battery 13 from DC to AC and convert the electricity regenerated by the rear motor 15 from AC to DC. In the hybrid vehicle 1 configured in this manner, electricity is supplied from the drive battery 13 to the generator 12, which then starts the engine 11.

[0020] The hybrid vehicle 1 according to the embodiment is capable of EV running, series running, and parallel running, but parallel running is not necessarily possible. EV running is running in which electricity is supplied from the drive battery 13 to the front motor 14 and the rear motor 15 with the engine 11 stopped. Series running is running in which electricity is supplied from the generator 12 or the drive battery 13 to the front motor 14 and the rear motor 15 with the engine 11 in operation, and electricity generated by the generator 12 can be rectified and charged to the drive battery 13. Parallel running is running in which the drive force of the engine 11 is transmitted to the front wheels with the engine 11 in operation, and electricity can be supplied from the drive battery 13 to the front motor 14 and the rear motor 15 (motor assist).

[0021] [Hybrid vehicle control configuration] As shown in FIG. 2, in addition to the above-mentioned FPDU 31 and RMCU 32, the hybrid vehicle according to the embodiment is equipped with a battery management unit (BMU) 33 that manages the drive battery 13, an engine control unit (engine ECU) 34 that controls the engine 11, and a vehicle control unit (HEV-ECU) 35 that controls these.

[0022] The BMU 33, the engine ECU, and the HEV-ECU each include a processor that is made up of an arithmetic unit, registers that store instructions and information, and peripheral devices, memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory), and an input interface.

[0023] The FPDU 31, RMCU 32, and BMU 33 are connected to an HEV-ECU 35 via a CAN (EV-CAN) 36, and the engine ECU 34 is connected to the HEV-ECU 35 via a CAN (CAN-C) 37. An accelerator position sensor 39 that detects the amount of depression of an accelerator pedal 38 is connected to the HEV-ECU 35, and the HEV-ECU 35 calculates a required output based on the amount of depression of the accelerator pedal 38 and the vehicle speed (the number of rotations of the front wheels (rear wheels)).

[0024] The HEV-ECU 35 constitutes a driving control device 40 that, when starting the engine 11 during EV driving in which electricity is supplied from the drive battery 13 to the front motor 14 and the rear motor 15 with the engine 11 stopped, changes the output distribution of the overall output to the front drive system 22 and the rear drive system 23 so as to increase the overall efficiency of the drive system made up of the front drive system 22 including the front motor 14 and the front transaxle 17, and the rear drive system 23 including the rear motor 15 and the rear transaxle 19. The efficiencies of the front motor 14 and the front transaxle 17, and the rear motor 15 and the rear transaxle 19 vary depending on the model, and are obtained, for example, by experiments and provided by a supplier.

[0025] As shown in FIG. 3, the driving control device 40 includes an overall efficiency storage unit 41, an output allocation specification unit 42, and an output change unit 43.

[0026] The overall efficiency storage unit 41 stores overall efficiencies associated with the rotation speed (revolutions per hour) of the front wheels 16 and the output distributed to the front drivetrain 22, as well as the rotation speed (revolutions per hour) of the rear wheels 18 and the output distributed to the rear drivetrain 23. When the hybrid vehicle 1 travels straight, the rotation speed of the front wheels 16 and the rotation speed of the rear wheels 18 are the same, and the overall efficiency storage unit 41 stores overall efficiencies associated with the rotation speed of the front wheels 16 (the rotation speed of the rear wheels 18), the output distributed to the front drivetrain 22, and the output distributed to the rear drivetrain 23.

[0027] Fig. 4 shows an example of the overall efficiency associated with the power distributed to the front drivetrain 22 and the rear drivetrain 23 when the overall power to the front drivetrain 22 and the rear drivetrain 23 is 175 kW and the rotation speed of the front wheels 16 (the rotation speed of the rear wheels 18) is 500 rpm. Eight types of power distribution are shown here, but the number of types is not limited to eight. As shown in Fig. 4, changing the power distribution changes the overall efficiency, and therefore changing the power distribution can improve the overall efficiency.

[0028] As shown in FIG. 3, the driving control device 40 according to the embodiment includes a front drive system efficiency memory unit 44, a rear drive system efficiency memory unit 45, a front drive system efficiency identification unit 46, a rear drive system efficiency identification unit 47, and an overall efficiency calculation unit 48, and the above-mentioned overall efficiency memory unit 41 may store the overall efficiency calculated by the overall efficiency calculation unit 48.

[0029] The front drivetrain efficiency storage unit 44 stores the efficiency of the front drivetrain 22 associated with the rotation speed of the front wheels 16 and the output distributed to the front drivetrain 22. The front drivetrain efficiency storage unit 44 stores, for example, the rotation speed and torque of the front wheels 16 and the output distributed to the front drivetrain 22 as shown in Fig. 5-1, and the rotation speed and torque of the front wheels 16 and the efficiency of the front drivetrain 22 as shown in Fig. 5-2. The output distributed to the front drivetrain 22 is calculated by the following Equation 1.

[0030]

number

[0031] The rear drivetrain efficiency storage unit 45 stores the efficiency of the rear drivetrain 23 associated with the rotation speed of the rear wheels 18 and the output distributed to the rear drivetrain 23. The rear drivetrain efficiency storage unit 45 stores, for example, the rotation speed and torque of the rear wheels 18 and the output distributed to the rear drivetrain 23 as shown in Fig. 6-1, and the rotation speed and torque of the rear wheels 18 and the efficiency of the rear drivetrain 23 as shown in Fig. 6-2. The output distributed to the rear drivetrain 23 is calculated by the following Equation 2.

[0032]

number

[0033] The front drivetrain efficiency specifying unit 46 specifies the efficiency of the front drivetrain 22 based on the rotation speed of the front wheels 16 and the power distributed to the front drivetrain 22. For example, in the example shown in Figures 5-1 and 5-2, when the rotation speed of the front wheels 16 is 500 rpm and the power distributed to the front drivetrain 22 is 147 kW, the torque is 2800 Nm and the efficiency of the front drivetrain 22 is 90%.

[0034] The rear drivetrain efficiency specifying unit 47 specifies the efficiency of the rear drivetrain 23 based on the rotation speed of the rear wheels 18 and the power distributed to the rear drivetrain 23. For example, in the example shown in Fig. 6-1 and Fig. 6-2, when the rotation speed of the rear wheels 18 is 500 rpm and the power distributed to the rear drivetrain 23 is 31.4 kW, the torque is 600 Nm and the efficiency of the rear drivetrain 23 is 94%.

[0035] The overall efficiency calculation unit 48 calculates the overall efficiency based on the output distributed to the front drivetrain 22 and the output distributed to the rear drivetrain 23, as well as the efficiency of the front drivetrain 22 and the efficiency of the rear drivetrain 23. The overall efficiency can be calculated from the output distributed to the front drivetrain 22 and the efficiency of the front drivetrain 22, as well as the output distributed to the rear drivetrain 23 and the efficiency of the rear drivetrain 23, as shown in the following equation 3.

[0036]

number

[0037] In this manner, the efficiency of the front drive system 22 is determined based on the rotation speed of the front wheels 16 and the power distributed to the front drive system 22, and the efficiency of the rear drive system 23 is determined based on the rotation speed of the rear wheels 18 and the power distributed to the rear drive system 23. Then, the overall efficiency of the drive system consisting of the front drive system 22 and the rear drive system 23 is calculated based on the power distributed to the front drive system 22 and the power distributed to the rear drive system 23, as well as the efficiency of the front drive system 22 and the efficiency of the rear drive system 23, and is stored in an overall efficiency memory unit 41.

[0038] The output distribution specification unit 42 specifies the output to be distributed to the front drivetrain 22 and the rear drivetrain 23 based on the rotation speed of the front wheels 16 and the rotation speed of the rear wheels 18, and the overall efficiency. As described above, when the hybrid vehicle 1 travels straight, the rotation speed of the front wheels 16 and the rotation speed of the rear wheels 18 are the same, and by specifying the rotation speed of the front wheels 16 (the rotation speed of the rear wheels 18) and the overall efficiency, the output to be distributed to the front drivetrain 22 and the rear drivetrain 23 are specified.

[0039] For example, as shown in the example of Figure 4, if the rotation speed of the front wheels 16 (the rotation speed of the rear wheels 18) is 500 rpm and the overall efficiency is 93.4%, the output distributed to the front drivetrain 22 is 94.2 kW, and the output distributed to the rear drivetrain 23 is 80.8 kW.

[0040] The output change unit 43 changes the output distribution of the total output between the front drive train 22 and the rear drive train 23 so as to increase the overall efficiency. For example, when the overall efficiency is low, the output change unit 43 changes the output distribution of the total output between the front drive train 22 and the rear drive train 23 so as to increase the overall efficiency.

[0041] For example, as shown in the example of Figure 4, if the output allocated to the front drive system 22 is 157 kW, the output allocated to the rear drive system 23 is 18 kW, and the overall efficiency is 90.4%, the output allocated to the front drive system 22 is set to 94.2 kW and the output allocated to the rear drive system 23 is set to 80.8 kW so that the overall efficiency is 93.4%.

[0042] The output change unit 43 according to the embodiment changes the output of the front motor 14 and the output of the rear motor 15 to change the output distribution of the total output to the front drive system 22 and the rear drive system 23. When starting the engine 11 during EV running, it is preferable that the vehicle speed of the hybrid vehicle 1 does not change, and it is preferable that the rotation speed of the front wheels 16 (the rotation speed of the rear wheels 18) does not change before and after the engine is started. Therefore, it is preferable that the vehicle change unit according to the embodiment has a torque change unit 49 that changes the torque of the front motor 14 and the torque of the rear motor 15 to change the output distribution of the total output to the front drive system 22 and the rear drive system 23. In this way, the torque change unit 49 can change the torque of the front motor 14 and the torque of the rear motor 15 to change the output distribution of the total output to the front drive system 22 and the rear drive system 23.

[0043] [Hybrid vehicle control operation] As shown in FIG. 7, in the hybrid vehicle 1 according to the embodiment, first, it is determined whether or not the vehicle is in EV driving (step S11). If the hybrid vehicle 1 is in EV driving, it is determined whether or not there is a request to start the engine 11 (step S12). In the example shown in FIG. 4, if the required output exceeds 175 kW, the engine 11 is requested to be started. If the hybrid vehicle 1 is in EV driving and there is a request to start the engine 11, the overall efficiency of the hybrid vehicle 1 is determined (step S13). In the example shown in FIG. 4, if the output of the front drivetrain 22 is 136 kW and the output of the rear drivetrain 23 is 39 kW, the efficiency of the front drivetrain 22 is 91%, the efficiency of the rear drivetrain 23 is 94%, and the overall efficiency is 91.7%.

[0044] Next, it is determined whether there is an output distribution with a higher overall efficiency than the identified overall efficiency (step S14). In the example shown in FIG. 4, there is an output distribution with an overall efficiency of 93.4%, which is higher than the identified overall efficiency of 91.7%. If there is an output distribution with an overall efficiency higher than the identified overall efficiency, the output distribution for the front drivetrain 22 and the rear drivetrain 23 is identified (step S15). In the example shown in FIG. 4, an output distribution with an output of 94.2 kW for the front drivetrain 22 and an output of 80.8 kW for the rear drivetrain 23 is identified. Next, the output distribution for the front drivetrain 22 and the rear drivetrain 23 is changed to the identified output distribution, and electricity is supplied from the drive battery 13 to the generator 12, so that the generator 12 starts the engine 11 (step S16). As a result, the engine 11 is started, and the hybrid vehicle 1 switches from EV running to series running.

[0045] [Effects of hybrid vehicles] According to the hybrid vehicle 1 according to this embodiment, when the engine 11 is started during EV running, the overall efficiency of the drive system is increased, so that hesitation occurring in the hybrid vehicle 1 can be suppressed.

[0046] For example, when a request to start the engine 11 is made, the output of the front drivetrain 22 is 136 kW and the output of the rear drivetrain 23 is 39 kW, and by changing the output distribution, the output of the front drivetrain 22 becomes 94.2 kW and the output of the rear drivetrain 23 becomes 80.8 kW, and the overall efficiency improves from 91.7% to 93.4% (efficiency difference is 1.7%). As a result, the usable output of the hybrid vehicle 1 increases by 1.7% of the overall output, and the magnitude of that output is 3.0 kW. For example, when the generator 12 secures 10 kW to start the engine 11, hesitation can be suppressed by 30%.

[0047] The present invention is not limited to the above-described embodiment, and includes modifications to the above-described embodiment and appropriate combinations of these modifications. [Explanation of symbols]

[0048] 1 Hybrid vehicles 11 Engine 12. Generator 13 Drive battery 14 Front motor 15 Rear motor 16 Front wheel 17 Front transaxle 18 Rear wheel 19 Rear transaxle 20 Fuel piping 21 Fuel Tank 22 Front drive system 23 Rear drive system 31 Front Power Drive Unit (FPDU) 32 Rear motor control unit 33 Battery Management Unit (BMU) 34 Engine control unit (engine ECU) 35 Vehicle control unit (HEV-ECU) 36 CAN (EV-CAN) 37 CAN (CAN-C) 38 Accelerator pedal 39 Accelerator position sensor 40 Driving control device 41 Overall Efficiency Memory Unit 42 Output allocation specification section 43 Output change section 44 Front drive system efficiency memory section 45 Rear drive system efficiency memory section 46 Front drive system efficiency specification part 47 Rear drive system efficiency specification part 48 Overall efficiency calculation section 49 Torque change section

Claims

1. The engine, a generator driven by the engine; a drive battery that stores the electricity generated by the generator; a front motor and a rear motor to which electricity is supplied from the generator or the drive battery; a front transaxle provided between the front motor and front wheels, the front transaxle transmitting driving force of the front motor to the front wheels; a rear transaxle provided between the rear motor and rear wheels and configured to transmit a driving force of the rear motor to the rear wheels; Equipped with A four-wheel drive hybrid vehicle in which the generator starts the engine by supplying electricity from the drive battery to the generator, A four-wheel drive hybrid vehicle equipped with a driving control device that, when the engine is started during EV driving in which electricity is supplied from the drive battery to the front motor and the rear motor with the engine stopped, changes the output distribution of overall output to the front drive system and the rear drive system so as to increase the overall efficiency of the drive system consisting of a front drive system including the front motor and the front transaxle, and a rear drive system including the rear motor and the rear transaxle.

2. The driving control device includes: an overall efficiency storage unit configured to store an overall efficiency associated with the rotation speed of the front wheels and the output distributed to the front drivetrain, and an overall efficiency associated with the rotation speed of the rear wheels and the output distributed to the rear drivetrain; an output distribution specifying unit that specifies an output to be distributed to the front drivetrain and an output to be distributed to the rear drivetrain based on the rotation speed of the front wheels, the rotation speed of the rear wheels, and the overall efficiency; an output change unit that changes an output distribution of an overall output to the front drive system and the rear drive system so as to increase the overall efficiency; 2. The four-wheel drive hybrid vehicle of claim 1 .

3. The driving control device includes: a front drivetrain efficiency storage unit configured to store an efficiency of the front drivetrain associated with a rotation speed of the front wheels and an output distributed to the front drivetrain; a rear drive system efficiency storage unit configured to store an efficiency of the rear drive system associated with a rotation speed of the rear wheels and an output distributed to the rear drive system; a front drivetrain efficiency determination unit that determines an efficiency of the front drivetrain based on a rotation speed of the front wheels and an output distributed to the front drivetrain; a rear drive system efficiency determination unit that determines an efficiency of the rear drive system based on a rotation speed of the rear wheels and an output distributed to the rear drive system; an overall efficiency calculation unit that calculates the overall efficiency based on an output distributed to the front drive system and an output distributed to the rear drive system, and an efficiency of the front drive system and an efficiency of the rear drive system; Including, 3. The four-wheel drive hybrid vehicle according to claim 2, wherein the overall efficiency storage unit stores the overall efficiency calculated by the overall efficiency calculation unit.

4. 3. The four-wheel drive hybrid vehicle according to claim 2, wherein the output change unit includes a torque change unit that changes the torque of the front motor and the torque of the rear motor.

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