JP7010042B2 - Braking force control device - Google Patents

Description

This specification discloses a braking force control device for a vehicle.

Patent Document 1 discloses a vehicle control method. The vehicle is equipped with a brake system and a brake controller. The brake system includes a brake pedal, an actuator, and a foil cylinder. When the driver depresses the brake pedal and determines that the vehicle is parked on a slope, the brake controller controls the actuator to maintain hydraulic pressure in the foil cylinder. The brake controller does not reduce the hydraulic pressure of the foil cylinder even when the brake pedal is released from the state where the brake pedal is depressed by the driver. As a result, braking force is applied to the vehicle so that the vehicle does not descend the slope.

Japanese Unexamined Patent Publication No. 2017-128218

In the above technology, the control of the actuator by the brake controller is released at the timing when the vehicle stopped on the slope starts, and the hydraulic pressure of the foil cylinder drops sharply. In this configuration, for example, if the driver releases the accelerator and the vehicle loses the propulsive force to move forward after the vehicle starts, the braking force is not applied to the vehicle and the vehicle may descend from the slope.

The present specification provides a technique capable of suppressing a situation in which a vehicle descends from a slope when the vehicle is started from a state where the vehicle is stopped on the slope.

The braking force control device disclosed in the present specification is a braking device including a brake operating unit operated by a driver, and is a braking force control device that controls the braking device that applies a braking force for braking a vehicle. The acquisition unit for acquiring the speed of the vehicle, the specific unit for specifying that the vehicle is located on the slope, and the specific unit for specifying that the vehicle is located on the slope are specified, and the vehicle is stopped. The above-mentioned for suppressing the vehicle from descending the slope when the speed indicating that the speed is acquired and the braking operation for braking the vehicle is not executed by the driver on the brake operation unit. A control unit that causes the braking device to execute a restraining operation for applying a braking force. When the speed to be increased is acquired while the suppressing operation is being executed, the braking force is increased according to the increase in the speed. May be provided with the control unit, which gradually lowers the speed.

In the above configuration, when an ascending speed is acquired, the braking force is gradually decreased as the speed increases. According to this configuration, when the vehicle is started from a state where it is stopped on a slope, the vehicle is off the slope even in a situation where the propulsive force of the vehicle is lost, for example, when the driver releases the accelerator after the start. It is possible to suppress the situation of descent.

It is a block diagram which shows the structure of a vehicle. It is a block diagram which shows the structure of a vehicle. It is a block diagram which shows the brake device of a vehicle. It is a figure which shows the transition of the speed of a vehicle and the hydraulic pressure of a foil cylinder at the time of starting a vehicle stopped on a slope. It is a figure which shows the transition between the speed of a vehicle and the oil pressure of a foil cylinder when the speed of a vehicle becomes zero immediately after starting a vehicle stopped on a slope.

The braking force control device 50 of this embodiment will be described with reference to FIGS. 1 to 5. The braking force control device 50 is mounted on a vehicle 10 such as an automobile. The braking force control device 50 controls the braking device 30 described later. As a result, braking force is applied to the vehicle 10.

As shown in FIGS. 1, 2, and 3, the vehicle 10 includes a drive device 12, a brake device 30, a braking force control device 50, a speed sensor 22, an acceleration sensor 24, and a shift position sensor 26. And the wheels 20.

The drive device 12 and the wheels 20 are mounted on the vehicle 10. As shown in FIG. 1, the drive device 12 includes an engine 14, a transmission 16, and an accelerator operation unit 18. The engine 14 burns fuel to generate torque. A transmission 16 is connected to the engine 14. The transmission 16 transmits the torque generated by the engine 14 to the wheels 20. The accelerator operation unit 18 includes an accelerator pedal operated by the driver. The driver changes the rotation speed of the engine 14 by changing the operation amount of the accelerator operation unit 18. As a result, the torque generated from the engine 14 fluctuates.

The brake device 30 is mounted on the vehicle 10. The braking device 30 generates a braking force for braking the vehicle 10. As shown in FIG. 3, the brake device 30 includes a brake operation unit 32, a booster 34, a master cylinder 36, connecting pipes 38, 41, an actuator 40, and foil cylinders 42, 44, 46, 48. To prepare for. The brake operation unit 32 includes a brake pedal operated by the driver. When the driver executes the operation of the brake operation unit 32 (for example, when the brake pedal is depressed), the operation force is amplified by the booster 34 and output to the master cylinder 36. As a result, hydraulic pressure is generated in the master cylinder 36. An actuator 40 is connected to the master cylinder 36 via a connecting pipe 38. The actuator 40 communicates or closes the actuator 40 and the master cylinder 36. Foil cylinders 42, 44, 46, 48 are connected to the actuator 40 via a connecting pipe 41. The foil cylinders 42, 44, 46, 48 communicate with the actuator 40. Hydraulic pressure is supplied to the foil cylinders 42, 44, 46, 48 from the master cylinder 36 via the actuator 40 and the connecting pipes 38, 41. Each of the foil cylinders 42, 44, 46, 48 is connected to the wheel 20. The foil cylinders 42, 44, 46, 48 apply a braking force to the wheels 20, that is, the vehicle 10 by the hydraulic pressure supplied from the master cylinder 36. The operation of the driver on the brake operation unit 32 (for example, the operation of stepping on the brake pedal) at this time is called a braking operation.

The speed sensor 22 is mounted on the vehicle 10. The speed sensor 22 includes a rotation speed detection unit and a conversion circuit. The speed sensor 22 detects the rotation speed of the wheel 20 in the rotation speed detection unit. The speed sensor 22 calculates the speed of the vehicle 10 from the rotation speed of the wheel 20 in the conversion circuit.

The acceleration sensor 24 is mounted on the vehicle 10. The acceleration sensor 24 detects each of the accelerations of the vehicle 10 in the horizontal direction and the vertical direction with respect to the vehicle 10.

The shift position sensor 26 is mounted on the vehicle 10. The shift position sensor 26 detects the shift position designated by the shift lever (not shown). Shift positions include, for example, drive, reverse, neutral, parking and the like. The shift position is a first-class shift position (for example, drive, reverse, etc.) in which the torque of the engine 14 is transmitted to the wheel 20, and a second-class shift position (for example, parking, etc.) in which the torque of the engine 14 is not transmitted to the wheel 20. (Neutral, etc.) and. In the case of an electric vehicle, the shift position may be classified according to whether or not the torque of the motor is transmitted to the wheels 20 instead of the engine 14 or together with the engine 14.

The braking force control device 50 is mounted on the vehicle 10. As shown in FIG. 2, the braking force control device 50 includes a control unit 52, an acquisition unit 54, a specific unit 56, and a shift position determination unit 58. The control unit 52 is electrically connected to the acquisition unit 54, the specific unit 56, the shift position determination unit 58, and the brake device 30. The control unit 52 controls the brake device 30. The acquisition unit 54 is electrically connected to the speed sensor 22. The acquisition unit 54 acquires the speed of the vehicle 10 from the speed sensor 22. The specific unit 56 is electrically connected to the acceleration sensor 24. The specific unit 56 acquires a detection result from the acceleration sensor 24. The specific unit 56 specifies whether or not the vehicle 10 is stopped on a slope from the acquired detection result. The shift position determination unit 58 is electrically connected to the shift position sensor 26. The shift position determination unit 58 acquires the shift position from the shift position sensor 26. The shift position determination unit 58 determines whether or not the acquired shift position is a type 2 shift position.

Next, the operation of the braking force control device 50 will be described with reference to FIG. While the engine 14 is driving, the acquisition unit 54 acquires the speed of the vehicle 10 from the speed sensor 22. Further, the specifying unit 56 acquires a detection result from the acceleration sensor 24 and specifies whether or not the vehicle 10 is located on a slope. Further, the shift position determination unit 58 acquires the shift position from the shift position sensor 26 and determines whether or not it is the second type shift position.

Subsequently, the processing of the braking force control device 50 in the situation where the vehicle 10 starts from the state of being stopped on the slope will be described. In a situation where the vehicle 10 starts from a state of being stopped on a slope, the driver executes a braking operation on the brake operation unit 32 and switches the shift position from the second type shift position to the first type shift position. Subsequently, the driver stops the braking operation of the brake operation unit 32 and shifts to the operation of the accelerator operation unit 18.

Until the braking operation by the driver is stopped, the acquisition unit 54 acquires the speed (that is, zero) of the vehicle 10 from the speed sensor 22. Thereby, the control unit 52 can specify that the vehicle 10 is stopped. Further, the specifying unit 56 can acquire the detection result from the acceleration sensor 24 and specify that the vehicle 10 is located on the slope. Further, the shift position determination unit 58 can determine that the shift position is not the second type of shift position. In this state, as shown in FIG. 4, at time T0, the braking operation by the brake operation unit 32 is executed (the brake operation is ON in FIG. 4), and the vehicle 10 is stopped. At this time, the master cylinder 36 and the actuator 40 communicate with each other, the hydraulic pressure converted by the master cylinder 36 is supplied to the foil cylinders 42, 44, 46, 48, and the rotation of the wheels 20 is stopped. As a result, the control unit 52 controls the braking device 30 to apply a braking force for suppressing the vehicle 10 from descending the slope to the vehicle 10.

Subsequently, at time T1, if the braking operation is not executed after the braking operation by the driver is stopped, the control unit 52 controls the actuator 40 to form the master cylinder 36 and the actuator 40. Switch the connection from the communication state to the closed state. As a result, when the braking operation by the brake operation unit 32 is not executed, the hydraulic pressure supplied to the wheel cylinders 42, 44, 46, 48 is the hydraulic pressure when the braking operation by the brake operation unit 32 is executed. It is held the same, and the braking force applied to the vehicle 10 is held. As a result, even if the braking operation is not executed, it is possible to execute the suppressing operation of suppressing the descent of the vehicle 10 from the slope.

Subsequently, at time T2, the operation of the accelerator operation unit 18 is executed (accelerator operation is ON in FIG. 4), the torque generated by the engine 14 is transmitted to the wheels 20, and the vehicle 10 starts (that is, the speed of the vehicle 10). Exceeds zero). Note that in FIG. 4, the time lag from the execution of the operation of the accelerator operation unit 18 to the start of the vehicle 10 is not shown. Subsequently, after the vehicle 10 starts, the control unit 52 gradually applies the hydraulic pressure of the foil cylinders 42, 44, 46, and 48 as the speed of the vehicle 10 increases from zero between the time T2 and the time T3. To reduce to. Specifically, as the speed of the vehicle 10 increases, the control unit 52 controls the actuator 40 to gradually communicate the master cylinder 36 and the actuator 40. As a result, the hydraulic pressure of the foil cylinders 42, 44, 46, 48 gradually decreases. As a result, the braking force of the braking device 30 gradually decreases. Here, "gradually reducing the braking force" means gradually reducing the hydraulic pressure of the foil cylinders 42, 44, 46, 48. Further, "gradually reducing the braking force" means, for example, in a situation where the vehicle 10 is located on a non-slope road (for example, a flat road), rather than a decrease in the braking force after the braking operation is released. It means slow. As a result, as the speed of the vehicle 10 increases, the braking force of the braking device 30 is gradually reduced. Then, at the time T3 when the speed of the vehicle 10 reaches the predetermined speed Vp, the hydraulic pressure of the wheel cylinders 42, 44, 46, 48 becomes zero, and the suppression operation is released (that is, the braking force from the braking device 30 is zero). become). Even if the speed of the vehicle 10 increases after the time T3, it is maintained at zero by the hydraulic pressure of the foil cylinders 42, 44, 46, 48 until the braking operation is executed.

In the above configuration, when the speed of the vehicle 10 increases, the braking force is gradually reduced as the speed increases. According to this configuration, when the vehicle 10 is started from a state of being stopped on a slope, it is possible to suppress a situation in which the vehicle 10 descends from the slope.

Next, with reference to FIG. 5, the processing of the braking force control device 50 in the situation where the vehicle 10 immediately returns to zero after the vehicle 10 is stopped will be described. This situation is, for example, a situation where the vehicle 10 is parked on a slope. In this situation, the driver executes the braking operation on the brake operation unit 32 and shifts the shift position from the second type shift position to the first type, as in the situation where the vehicle 10 starts from the state of being stopped on the slope. Switch to the shift position of. Subsequently, the driver stops the braking operation of the brake operation unit 32 and shifts to the operation of the accelerator operation unit 18.

In this situation, the time T10 to T12 is the same as the time T0 to T2 in the situation where the vehicle 10 starts from the state where the vehicle 10 is stopped on the slope. Subsequently, when the operation of the accelerator operation unit 18 is executed (accelerator operation ON in FIG. 5) at the time T12, the speed of the vehicle 10 is smaller than the predetermined speed Vp from zero between the time T12 and the time T13. It rises to speed V1. The control unit 52 gradually lowers the hydraulic pressure of the foil cylinders 42, 44, 46, 48. The operation amount of the accelerator operation unit 18 is reduced between the time 12 and the time T13, and the speed of the vehicle 10 is reduced to zero between the time T13 and the time T14.

According to this configuration, the speed of the vehicle 10 is increased only to the speed V1 smaller than the predetermined speed Vp, and the hydraulic pressure of the foil cylinders 42, 44, 46, 48 is not lowered to zero. Therefore, even if the operation amount of the accelerator operation unit 18 is reduced and the propulsive force of the vehicle 10 is reduced, the braking force of the brake device 30 is maintained and the vehicle 10 is prevented from descending the slope. At this time, the hydraulic pressure of the foil cylinders 42, 44, 46, 48 is held to be the same as the hydraulic pressure of the foil cylinders 42, 44, 46, 48 at the speed V1 of the vehicle 10. When the operation of the accelerator operation unit 18 is executed again at the time T14, the speed of the vehicle 10 increases from zero. The hydraulic pressure of the foil cylinders 42, 44, 46, 48 is maintained in the same manner as the hydraulic pressure of the foil cylinders 42, 44, 46, 48 at the speed V1 of the vehicle 10. Subsequently, at time T15, when the speed of the vehicle 10 reaches the speed V1, the control unit 52 starts lowering the hydraulic pressure of the foil cylinders 42, 44, 46, 48. The oil pressure of the foil cylinders 42, 44, 46, 48 is gradually lowered until the time T16 when the speed of the vehicle 10 reaches the speed V2 which is larger than the speed V1 and smaller than the predetermined speed Vp. When the operation amount of the accelerator operation unit 18 is reduced between the time T15 and the time T16, the speed of the vehicle 10 is reduced to zero between the time T16 and the time T17. The hydraulic pressure of the foil cylinders 42, 44, 46, 48 is maintained in the same manner as the hydraulic pressure of the foil cylinders 42, 44, 46, 48 at the speed V2 of the vehicle 10. When the operation of the accelerator operation unit 18 is executed at the time T17, the speed of the vehicle 10 increases from zero to the speed V1 between the time T17 and the time T18. When the operation amount of the accelerator operation unit 18 is reduced between the time T17 and the time T18, the speed of the vehicle 10 is reduced to zero between the time T18 and the time T19. Since the speed of the vehicle 10 does not exceed the speed V2 between the time T17 and the time T19, the hydraulic pressure of the wheel cylinders 42, 44, 46, 48 is the wheel cylinders 42, 44, 46, at the speed V2 of the vehicle 10. It is held the same as the hydraulic pressure of 48. The master cylinder 36 and the actuator 40 are communicated with each other by the control unit 52 at a time T19 when a predetermined time has elapsed from the time T11 when the braking operation by the brake operation unit 32 is released. The hydraulic pressure of the foil cylinders 42, 44, 46, 48 drops sharply to zero.

As a result, even in a situation where the vehicle 10 immediately returns to zero after the vehicle 10 is stopped, the braking force in the braking device 30 is prevented from suddenly decreasing, and the braking force is applied to the vehicle 10. As a result, it is possible to prevent the vehicle 10 from descending the slope.

While the restraining operation is being executed, the hydraulic pressure of the foil cylinders 42, 44, 46, 48 gradually decreases as the speed of the vehicle 10 increases. Therefore, as the speed of the vehicle 10 increases, the braking force applied to the vehicle 10 gradually decreases. As a result, the vehicle 10 is started with a small braking force applied to the vehicle 10 as compared with the case where the hydraulic pressure of the foil cylinders 42, 44, 46, 48 is kept constant even if the speed of the vehicle 10 increases. be able to. This makes it possible to reduce the drag feeling of the vehicle 10 when the vehicle 10 starts. Further, as shown in FIG. 4, for example, the gradient of the speed of the vehicle 10 is constant before and after the time T13 when the suppression operation is released. As a result, for example, as compared with the case where the hydraulic pressure of the foil cylinders 42, 44, 46, 48 decreases when the suppression operation is released, the sudden increase in speed of the vehicle 10 due to the release of the suppression operation is suppressed. can do.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples exemplified above. The technical elements described herein or in the drawings exhibit their technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the techniques exemplified in the present specification or the drawings can achieve a plurality of purposes at the same time, and achieving one of the purposes itself has technical usefulness.

10: Vehicle 12: Drive device 14: Engine 16: Transmission 18: Accelerator operation unit 20: Wheel 22: Speed sensor 24: Acceleration sensor 26: Shift position sensor 30: Brake device 32: Brake operation unit 34: Booster 36: Master Cylinders 38, 41: Connecting pipe 40: Actuator 42, 44, 46, 48: Wheel cylinder 50: Braking force control device 52: Control unit 54: Acquisition unit 56: Specific unit 58: Shift position determination unit

Claims (1)

A brake device including a brake operation unit operated by a driver, and a braking force control device for controlling the brake device that applies a braking force for braking a vehicle.
The acquisition unit that acquires the speed of the vehicle and
A specific part that identifies the vehicle as being located on a slope,
It is specified that the vehicle is located on the slope, the speed indicating that the vehicle is stopped is acquired, and the driver executes a braking operation for braking the vehicle on the brake operation unit. A control unit that causes the brake device to execute a suppression operation for applying the braking force to prevent the vehicle from descending the slope when the vehicle is not, and while the suppression operation is being executed. A control unit that gradually reduces the braking force according to the increase in the speed when the increasing speed is acquired is provided .
In the suppression operation, the braking force is reduced at a lowering rate that matches the rate of increase of the speed as the speed increases until the speed reaches a predetermined speed, and the speed is reduced. In the case, a braking force control device that keeps the braking force before the speed decrease until the speed reaches the speed before the speed decrease again .

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