JP7732376B2 - Hybrid vehicle control device - Google Patents

Description

The present invention relates to a control device for a hybrid vehicle.

Some hybrid vehicles have an internal combustion engine and two motors (see, for example, Patent Document 1). The engine and the first motor can transmit driving force to, for example, the rear wheels. The second motor can transmit driving force to, for example, the front wheels.

Japanese Patent Application Laid-Open No. 2021-098484

Drivability may deteriorate when switching driving modes. Therefore, the objective is to provide a control device for a hybrid vehicle that can improve drivability when switching driving modes.

The object is to provide a control device for a hybrid vehicle having an internal combustion engine and a first motor capable of transmitting driving force to first drive wheels, and a second motor capable of transmitting driving force to second drive wheels, the control device comprising: a driving mode control unit which controls a driving mode, and the first motor has a function of generating electricity using the driving force of the internal combustion engine; a driving force control unit which controls the driving force of the hybrid vehicle ; a first clutch control unit which controls a first clutch provided between the internal combustion engine and the first motor; and a second clutch control unit which controls a second clutch provided between the internal combustion engine, the first motor, and the first drive wheels, the driving mode control unit switching the driving mode between a first mode in which the first motor generates electricity using the driving force output by the internal combustion engine and the vehicle travels using the driving force of the second motor, a second mode in which the first motor does not generate electricity and the vehicle travels using the driving force of the second motor , and a third mode in which the vehicle travels using the driving forces of the internal combustion engine, the first motor, and the second motor, and when the driving mode is the third mode, the first clutch control unit switches the driving mode between the first clutch and the first motor. the second clutch control unit engages the second clutch; when the traveling mode control unit switches the traveling mode from the third mode to the first mode, the first clutch control unit releases the first clutch and the second clutch control unit releases the second clutch; the driving force control unit reduces the required driving force to a level lower than before the switching; after the required driving force is reduced to a level lower than before the switching, the first clutch control unit engages the released first clutch and the second clutch control unit engages the released second clutch; after the first clutch and the second clutch are engaged, the driving force control unit increases the required driving force to a level higher than the reduced required driving force; when the traveling mode control unit switches the traveling mode from the third mode to the second mode, the first clutch control unit releases the first clutch and the second clutch control unit releases the second clutch; and the driving force control unit reduces the required driving force to a level lower than before the switching and then increases the required driving force .

When switching from the third mode to the first mode or the second mode, the driving force control unit may set the required driving force to zero.

The hybrid vehicle may include an accelerator opening acquisition unit that acquires the accelerator opening of the hybrid vehicle, and the driving force control unit may reduce the required driving force to a value corresponding to the accelerator opening after reducing the required driving force from a value before the switching.

It is possible to provide a control device for a hybrid vehicle that can improve drivability when switching driving modes.

FIG. 1 is a schematic diagram illustrating a hybrid vehicle. FIG. 2 is a diagram illustrating a hybrid vehicle in series running mode. FIG. 3 is a diagram illustrating a hybrid vehicle in the rear motor driving mode. FIG. 4 is a flowchart illustrating the processing executed by the ECU.

(Hybrid vehicle)
FIG. 1 is a schematic diagram of a hybrid vehicle 1. The hybrid vehicle 1 has two front wheels 2f (first drive wheels) and two rear wheels 2r (second drive wheels). The hybrid vehicle 1 has an engine (ENG) 10 (internal combustion engine), a front motor (Fr-MG) 12 (first motor), and a rear motor (Rr-MG) 18 (second motor) as driving power sources. The engine 10 and the front motor 12 drive the front wheels 2f. The rear motor 18 drives the rear wheels 2r.

Hybrid vehicle 1 has a K0 clutch 11, a starting clutch 13, an automatic transmission (AT) 14, and a hydraulic control device 19. The starting clutch 13 and the automatic transmission 14 form a transmission unit 15. Hybrid vehicle 1 also includes a front power control unit (Fr-PCU) 20, a rear power control unit (Rr-PCU) 21, batteries (BAT) 22 and 24, a DC/DC converter 26, and an ECU (Electronic Control Unit) 30.

The engine 10 is, for example, a spark-ignition gasoline engine, but is not limited to this and may also be a compression-ignition diesel engine. The output torque of the engine 10 can be transmitted to the left and right front wheels 2f via the front differential gear 4f and the front drive shafts.

The front motor 12 functions as a generator that receives the output torque of the engine 10 to generate electricity, and as an electric motor that receives a supply of electric power to drive it. The rear motor 18 functions as a generator that receives torque transmitted from the rear wheels 2r to generate electricity, and as an electric motor that receives a supply of electric power to drive it. The output torque of the front motor 12 can be transmitted to the left and right front wheels 2f via the front differential gear 4f and the front drive shaft. The output torque of the rear motor 18 can be transmitted to the left and right rear wheels 2r via the rear differential gear 4r and the rear drive shaft.

The K0 clutch 11 is provided on the power transmission path between the engine 10 and the front motor 12 and can disconnect the engine 10 from the front motor 12.

The automatic transmission 14 is located on the same axis as the engine 10 and on the output side of the front motor 12. It is a transmission mechanism that transmits torque between the engine 10 and the front motor 12 and the front wheels 2f. The automatic transmission 14 transmits torque to the left and right front wheels 2f via the front differential gear 4f and front drive shafts. When the automatic transmission 14 is set to neutral, torque is no longer transmitted to the front wheels 2f.

The starting clutch 13 is located on the power transmission path between the front motor 12 and the automatic transmission 14, and selectively transmits and cuts off the torque of the engine 10 and the front motor 12. The starting clutch 13 is a hydraulic multi-plate clutch that can continuously change its transmission torque capacity.

The hydraulic control device 19 controls the engagement, release, and slip of the K0 clutch 11 and the starting clutch 13, as well as the gear shifting operation of the automatic transmission 14, using the pressure (hydraulic pressure) of the hydraulic oil as a working fluid. The hydraulic control device 19 includes various well-known hydraulic control circuits controlled by the ECU 30, and is configured to include, for example, multiple oil passages, an oil reservoir, an oil pump, multiple solenoid valves, etc.

The accelerator opening sensor 17 detects the amount of depression of the accelerator pedal (not shown) (accelerator opening).

A front power control unit 20 is connected to the front motor 12. A rear power control unit 21 is connected to the rear motor 18. A battery 24 is connected to the front power control unit 20 and the rear power control unit 21 via a DC/DC converter 26. A battery 22 is connected to the front power control unit 20 and the rear power control unit 21.

Batteries 22 and 24 are secondary batteries that can be discharged and charged. The power from battery 22 is used to drive auxiliary equipment such as an air conditioner. The power from battery 24 is used to drive the front motor 12 and rear motor 18.

The front power control unit 20 can store the power generated by the front motor 12 in the battery 22, and can also supply the stored power in the battery 22 to the front motor 12 to drive the front motor 12. The rear power control unit 21 can store the power generated by the rear motor 18 in the battery 22, and can also supply the stored power in the battery 22 to the rear motor 18 to drive the rear motor 18.

The ECU 30 includes a central processing unit (CPU), read-only memory (ROM), random access memory (RAM), non-volatile flash memory, and other storage devices. The ECU 30 executes the control described below in accordance with a control program pre-stored in the ROM, based on information from sensors and information pre-stored in the ROM and storage devices. The ECU 30 functions as an accelerator opening degree acquisition unit that acquires the accelerator opening degree, a clutch control unit that controls the K0 clutch 11, a driving mode control unit that controls the driving mode, and a driving force control unit that controls the driving force of the hybrid vehicle 1.

The ECU 30 is connected to the front power control unit 20 and rear power control unit 21 and controls the operation of these devices. The ECU 30 is connected to the accelerator position sensor 17 and acquires the accelerator position detected by the accelerator position sensor 17. The ECU 30 controls the K0 clutch 11 and starting clutch 13 using the hydraulic control device 19, and also controls the automatic transmission 14. The ECU 30 controls the engine 10, front motor 12, and rear motor 18, and controls their driving force. The ECU 30 can set the required driving force for the engine 10, front motor 12, and rear motor 18 according to the accelerator position, for example, and can also set the required driving force regardless of the accelerator position.

[Driving mode]
The ECU 30 switches the driving mode of the hybrid vehicle 1 between a series driving mode (first mode), an electric driving mode, and a parallel driving mode. Fig. 2 is a diagram illustrating the hybrid vehicle 1 in the series driving mode. Fig. 3 is a diagram illustrating the hybrid vehicle 1 in the rear motor driving mode. The arrows in Figs. 2 and 3 represent electric power.

As shown in Figure 2, in series driving mode, the K0 clutch 11 and the launch clutch 13 are engaged. The torque of the engine 10 is transmitted to the front motor 12. Because the automatic transmission 14 is set to neutral, the driving force of the engine 10 and front motor 12 is not transmitted to the front wheels 2f. The engine 10 generates electricity for the front motor 12, which charges the battery 22. The battery 22 then drives the rear motor 18, and the vehicle travels using the driving force of the rear motor 18. The series driving mode is suitable when the remaining capacity of the battery 22 is insufficient. In series driving mode, only the rear motor 18 is used as a driving power source, so it cannot handle cases where the required driving force of the hybrid vehicle 1 exceeds the maximum driving force of the rear motor 18.

In electric driving mode, there is a mode in which the vehicle runs using only the front motor 12 as the driving power source, and a mode in which the vehicle runs using only the rear motor 18. When running using only the front motor 12, the K0 clutch 11 is released and the launch clutch 13 is constantly engaged.

Of the electric driving modes, the mode in which the vehicle travels using only the driving force of the rear motor 18 is referred to as rear motor driving mode (second mode). Figure 3 is a diagram illustrating the hybrid vehicle 1 in rear motor driving mode. As shown in Figure 3, in rear motor driving mode, the K0 clutch 11 and the launch clutch 13 are disengaged. The front motor 12 does not generate electricity. The rear motor 18 is driven by the power output by the battery 22 and outputs torque. The driving force of the rear motor 18 is transmitted to the rear wheels 2r.

In electric driving mode, the engine 10 is stopped, improving fuel efficiency. Furthermore, electric driving mode is suitable when the battery 22 has sufficient remaining capacity. Even in electric driving mode, only the front motor 12 or rear motor 18 is used as the driving power source, so it cannot handle cases where the required driving force of the hybrid vehicle 1 exceeds the maximum driving force of the front motor 12 or rear motor 18.

In parallel driving mode, the K0 clutch 11 and launch clutch 13 are engaged, and the engine 10, front motor 12, and rear motor 18 are used as driving power sources for 4WD driving. Because the K0 clutch 11 is engaged, the rotational speed of the engine 10 and the rotational speed of the front motor 12 match. Parallel driving mode is suitable when the required driving force for the hybrid vehicle 1 is large.

Under normal circumstances, the engine 10 and front motor 12 are the main power sources. However, when the hybrid vehicle 1 is performing evacuation driving, the driving mode is set to series driving mode or rear motor driving mode, and the rear motor 18 is used as the power source. Switching the power source in response to a change in driving mode can cause changes in behavior, such as sudden acceleration. In this embodiment, changes in behavior when switching driving modes are suppressed, improving drivability.

Figure 4 is a flowchart illustrating the processing executed by the ECU 30 when switching between driving modes.

As shown in FIG. 4, the ECU 30 determines whether there is a request to switch to series driving mode (series driving transition request) (step S10). If the determination is affirmative (Yes), the ECU 30 disengages the K0 clutch 11 and the starting clutch 13 and disengages the automatic transmission 14 (shifts to neutral) (step S12). The ECU 30 sets the required driving force to zero regardless of the accelerator pedal position (step S14).

Then, the ECU 30 changes the hydraulic pressure of the K0 clutch 11 and the starting clutch 13 using the hydraulic control device 19 to engage them (step S15). The ECU 30 determines whether the engagement of the K0 clutch 11 and the starting clutch 13 has been completed (step S16). If the determination is negative, step S16 is repeated. If the determination is positive, the ECU 30 gradually increases the required driving force from zero, for example, to a driving force corresponding to the accelerator opening (step S18).

If the answer to step S10 is negative (No), the ECU 30 determines whether there is a request to switch to rear motor driving mode (rear motor driving transition request) (step S20). If the answer is positive, the ECU 30 releases the K0 clutch 11 and the starting clutch 13 and sets the automatic transmission 14 to neutral (step S22). The ECU 30 sets the required driving force to zero regardless of the accelerator pedal stroke (step S24). The ECU 30 determines whether the release of the K0 clutch 11 and the starting clutch 13 and the setting of the automatic transmission 14 to neutral have been completed (step S26). If the answer is negative, step S26 is repeated. If the answer is positive, the ECU 30 gradually increases the required driving force from zero, for example, to a driving force corresponding to the accelerator pedal stroke (step S28). If the answer to both steps S10 and S20 is negative after step S18 or S28, the process ends.

According to this embodiment, when switching to series running or rear motor running, the ECU 30 reduces the required driving force from a value before the switch, for example to zero (steps S14 and S24). The ECU 30 then increases the required driving force above the reduced value (for example, zero) (steps S18 and S28). By reducing the required driving force regardless of the accelerator pedal position, sudden changes in the behavior of the hybrid vehicle 1 when switching driving modes are suppressed. By increasing the required driving force that was temporarily set to zero, evacuation driving is possible in the driving mode after the switch (series running mode or rear motor running mode). Drivability can be improved when switching driving modes.

The ECU 30 reduces the required driving force, for example, to zero, and then increases it to a magnitude corresponding to the accelerator pedal position (steps S18 and S28). By setting the required driving force to zero, sudden changes in the behavior of the hybrid vehicle 1 can be suppressed. Furthermore, by increasing the required driving force from zero, a driving force corresponding to the driver's accelerator operation is output, improving drivability.

When switching to series driving mode, the ECU 30 temporarily releases the K0 clutch 11 and the starting clutch 13 (state in Figure 1, step S12 in Figure 4). Because the engine 10 is disconnected from the automatic transmission 14 and the front wheels 2f, the engine speed tends to be higher than before the disconnection. In this embodiment, the ECU 30 sets the required driving force to zero (step S14), thereby suppressing an increase in the engine speed of the engine 10. Compared to when the engine speed increases, the time required for the engine 10 and the front motor 12 to synchronize is shorter. This enables a quick switch to series driving mode.

In the above example, the hybrid vehicle 1 is controlled by a single ECU 30. However, the embodiment is not limited to this, and the above control may be performed by multiple ECUs, such as an engine ECU that controls the engine 10, a motor ECU that controls the front motor 12 and rear motor 18, and a clutch ECU that controls the K0 clutch 11.

Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited to such specific embodiment, and various modifications and variations are possible within the scope of the gist of the present invention as set forth in the claims.

1 Hybrid vehicle 2f Front wheels 2r Rear wheels 4f Front differential gear 4r Rear differential gear 10 Engine 11 K0 clutch 12 Front motor 13 Starting clutch 13
14 Automatic transmission 15 Transmission unit 17 Accelerator opening sensor 18 Rear motor 20 Front power control unit 21 Rear power control unit 22, 24 Battery 26 DC/DC converter 30 ECU

Claims (3)

A control device for a hybrid vehicle having an internal combustion engine and a first motor capable of transmitting driving force to first drive wheels, and a second motor capable of transmitting driving force to second drive wheels,
the first motor has a function of generating electricity using the driving force of the internal combustion engine,
a driving mode control unit that controls a driving mode;
a driving force control unit that controls the driving force of the hybrid vehicle;
a first clutch control unit that controls a first clutch provided between the internal combustion engine and the first motor;
a second clutch control unit that controls the internal combustion engine and a second clutch that is provided between the first motor and the first drive wheel ,
the traveling mode control unit switches the traveling mode among a first mode in which the first motor generates electricity using driving force output by the internal combustion engine and the vehicle travels using driving force from the second motor, a second mode in which the first motor does not generate electricity and the vehicle travels using driving force from the second motor , and a third mode in which the vehicle travels using driving forces from the internal combustion engine, the first motor, and the second motor ;
When the driving mode is the third mode, the first clutch control unit engages the first clutch, and the second clutch control unit engages the second clutch,
When the traveling mode control unit switches the traveling mode from the third mode to the first mode, the first clutch control unit releases the first clutch, the second clutch control unit releases the second clutch, the driving force control unit reduces the required driving force to a level lower than that before the switching, and after the required driving force has been reduced to a level lower than that before the switching, the first clutch control unit engages the released first clutch and the second clutch control unit engages the released second clutch, and after the first clutch and the second clutch are engaged, the driving force control unit increases the required driving force to a level higher than that at the time of the reduction,
a first clutch control unit disengaging the first clutch, a second clutch control unit disengaging the second clutch, and a driving force control unit reducing the required driving force to a level lower than that before the switching and then increasing the required driving force when the driving mode control unit switches the driving mode from the third mode to the second mode; The control device for a hybrid vehicle according to claim 1 , wherein the driving force control unit sets the required driving force to zero when switching from the third mode to the first mode or the second mode. an accelerator opening degree acquisition unit that acquires an accelerator opening degree of the hybrid vehicle;
3. The control device for a hybrid vehicle according to claim 1, wherein the driving force control unit reduces the required driving force to a value corresponding to the accelerator opening degree after the required driving force is reduced from a value before the switching.