Vehicle braking device

Abstract

To avoid a situation in which a vehicle continues to slide in a direction different from driver's intention when slipping occurs on an inclined road.SOLUTION: A vehicle braking device executes brake fluid pressure adjustment control when a vehicle begins to move on an inclined road with wheels in a locked state, and determines whether a moving direction of the vehicle matches a steering direction (S204). When the moving direction of the vehicle does not match the steering direction, the vehicle braking device reduces brake fluid pressure below a basic value corresponding to brake operation by a driver (S206). When the moving direction of the vehicle matches the steering direction, the vehicle braking device stops a reduction of the brake fluid pressure (S205). The vehicle braking device continues the brake fluid pressure adjustment control until the vehicle achieves deceleration during moving on the inclined road (S207).SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a braking device for a vehicle.

Background Art

[0002] There is a technique for operating an anti-lock brake (ABS) device to avoid a situation where all four wheels fall into a locked state.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] On a sloped road, when the friction coefficient of the road surface is low, a situation may occur where a parked vehicle slides down the road surface due to wheel slip. In such a situation, it is difficult to stop the slip and park the vehicle by repeatedly increasing and decreasing the brake hydraulic pressure like an ABS device. And in a situation where the vehicle is sliding down, it is also difficult for the driver to direct the vehicle in the direction intended by the driver (that is, the steering direction), and there is a concern that the vehicle will continue to slide in a direction different from the driver's intention. Specifically, even though the driver turns the steering wheel to the right or left, there is a concern that the vehicle will continue to slide straight down the sloped road.

[0005] In view of such a situation, an object of the present invention is to provide a braking device for a vehicle that can avoid a situation where the vehicle continues to slide in a direction different from the driver's intention when a slip occurs in the vehicle, contributing to further improvement in safety.

Means for Solving the Problems

[0006] To solve the above problems, a braking device for a vehicle according to an embodiment of the present invention includes a slope detection means for detecting that the vehicle is on a slope, a wheel lock detection means for detecting that the vehicle is in a wheel lock state, a vehicle state determination means for determining whether the moving direction of the vehicle on the slope coincides with the steering direction, and a brake hydraulic pressure setting means for setting the brake hydraulic pressure of the vehicle according to the driver's brake operation. The brake hydraulic pressure setting means reduces the brake hydraulic pressure below the basic value according to the driver's brake operation when the moving direction of the vehicle does not coincide with the steering direction while the vehicle is moving on the slope after starting to move in the wheel lock state, and implements brake hydraulic pressure adjustment control to stop the decompression of the brake hydraulic pressure when the moving direction of the vehicle coincides with the steering direction.

Effect of the Invention

[0007] According to one aspect of the present invention, after starting to move in the wheel lock state, when the moving direction of the vehicle does not coincide with the steering direction, in other words, when the vehicle is sliding down the slope in a direction different from the driver's intention, the brake hydraulic pressure of the vehicle is reduced by brake hydraulic pressure adjustment control. This promotes the elimination of the wheel lock state, restores the driver's steering ability, and enables the vehicle to be directed in the direction intended by the driver. Therefore, it is possible to avoid the situation where the vehicle continues to slide in a direction different from the driver's will on the slope, and it is possible to further improve safety.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0010] (Configuration of the Braking Device) FIG. 1 is a schematic diagram showing the configuration of a braking device (hereinafter simply referred to as "braking device") 1 of a vehicle according to an embodiment of the present invention.

[0011] The braking device 1 includes, as main components according to this embodiment, a brake pedal 11, a brake booster 12, a brake master cylinder 13, a brake oil reservoir 14, a front brake 15, and a rear brake 16.

[0012] The brake pedal 11 is an operating member that is depressed by the driver when applying the brake. In this embodiment, the brake pedal 11 constitutes an operating member for the foot brake, and the driver can adjust the braking force by the foot brake by increasing or decreasing the force or amount of depressing the brake pedal 11.

[0013] The brake booster 12 is a force multiplying device that assists in reducing the force required when the driver depresses the brake pedal 11, that is, the driver's brake operating force. In a vehicle equipped with an internal combustion engine as a drive source, a force multiplying effect is produced by introducing the intake negative pressure of the engine.

[0014] The brake master cylinder 13 is a pressure conversion device that converts the force applied by the driver when stepping on the brake pedal 11, specifically, the boosted brake operating force by the brake booster 12, into the pressure of the brake oil (hereinafter referred to as "brake fluid pressure"). The converted brake fluid pressure is transmitted to the front brake 15 and the rear brake 16 through the oil pipes P1, P2, and P3 filled with brake oil.

[0015] The brake oil reservoir 14 is a container that stores the excess brake oil in the brake master cylinder 13 and supplies the insufficient brake oil to the brake master cylinder 13 when there is an excess or deficiency in the brake oil stored in the brake master cylinder 13.

[0016] The front brake 15 is a brake provided on the front wheels of the vehicle, and in this embodiment, it is a disc brake. The front brake 15 includes a brake disc 151 and a brake caliper 152. The brake disc 151 is attached to the front wheels and is in a state of being rotatable integrally with the front wheels. The brake caliper 152 is arranged so as to sandwich the outer peripheral portion of the brake disc 151 from both the front and back. When the brake caliper 152 receives the supply of brake oil from the brake master cylinder 13 through the oil pipes P1 and P2, the brake pads 152a are actuated, and the brake disc 151 is clamped by the brake pads 152a. As a result, a frictional force is generated between the brake pads 152a and the brake disc 151, and a braking force is generated on the vehicle.

[0017] The rear brake 16 is a brake provided on the rear wheels of the vehicle, and like the front brake 15, it is a disc brake. The rear brake 16 includes a brake disc 161 and a brake caliper 162. The brake disc 161 is attached to the rear wheel and is in a state of being rotatable integrally with the rear wheel. The brake caliper 162 is arranged so as to sandwich the outer peripheral portion of the brake disc 161 from both its front and back sides. When the brake caliper 162 receives the supply of brake oil from the brake master cylinder 13 via the oil pipe P3, the brake pad 162a operates to clamp the brake disc 161 with the brake pad 162a. Thereby, a frictional force is generated between the brake pad 162a and the brake disc 161, and a braking force is generated on the vehicle.

[0018] In the present embodiment, in addition to the above, various sensors such as a pressure regulating valve 17, a controller 101, and a wheel speed sensor 113 are provided.

[0019] The pressure regulating valve 17 adjusts the pressure of the brake oil supplied to the brake caliper (hereinafter referred to as the "front brake caliper") 152 of the front brake 15, that is, the brake fluid pressure applied to the brake pad 152a of the front brake caliper 152. In the present embodiment, when attempting to release the locked state of the front wheels, a part of the brake oil supplied to the front brake caliper 152 is drawn out from the oil pipe P2 connecting the pressure regulating valve 17 and the front brake caliper 152, thereby reducing the brake fluid pressure. This part of the brake oil is returned to the brake oil reservoir 14 via the oil pipe P4 that bypasses the oil pipe P1 extending from the brake master cylinder 13 without passing through the oil pipe P1. The pressure regulating valve 17 is an actuator that operates in response to a command signal from the controller 101 and constitutes the output portion of the braking device 1.

[0020] The controller 101 constitutes the arithmetic unit of the braking device 1. The controller 101 is configured as an electronic control unit and is composed of a microcomputer including a central processing unit (CPU), an input / output interface, and storage units such as a ROM and a RAM. The controller 101 receives output signals from various sensors such as the wheel speed sensor 113, and executes predetermined operations stored in advance regarding braking control. Then, a command signal corresponding to the result of the operation is generated and output to various actuators including the pressure regulating valve 17.

[0021] (Configuration of the control system) FIG. 2 is a schematic diagram showing the configuration of the control system S provided in the braking device 1.

[0022] The signals received by the controller 101 as inputs include output signals from various sensors such as the accelerator opening sensor 111, the brake pedal force sensor 112, the wheel speed sensor 113, the inclination angle sensor 114, the acceleration sensor 115, the steering angle sensor 116, and the vehicle speed sensor 117.

[0023] The accelerator opening sensor 111 detects the operation amount of the accelerator pedal by the driver (hereinafter referred to as "accelerator operation amount"). The accelerator operation amount indicates the output torque required for a drive source such as an engine (that is, the target engine torque).

[0024] The brake pedal force sensor 112 detects the operation amount of the brake pedal by the driver (hereinafter referred to as "brake operation amount"). The brake operation amount is used by the controller 101 to set the brake fluid pressure applied to the brake pad 152a of the front brake caliper 152.

[0025] The wheel speed sensor 113 detects the rotational speed of the wheels provided for the running of the vehicle (hereinafter referred to as "wheel speed"). In this embodiment, wheel speed sensors 113 (113a to 113d) are provided for each of the four wheels of the vehicle, specifically, the right front wheel, the left front wheel, the right rear wheel, and the left rear wheel, and the wheel speed sensors 113a to 113d detect the wheel speed for each wheel. In this embodiment, the vehicle is of an FF (front engine · front drive) drive system, and the left and right front wheels are steering wheels and also drive wheels.

[0026] The inclination angle sensor 114 detects the inclination angle of the vehicle. The inclination angle of the vehicle indicates the inclination angle of the road surface when the vehicle is on an inclined road. Based on the inclination angle detected by the inclination angle sensor 114, the inclination direction of the road surface can be detected.

[0027] The acceleration sensor 115 detects the acceleration of the vehicle in the directions along the axes in the front-rear direction (roll axis), left-right direction (pitch axis), and up-down direction (yaw axis) passing through the center of gravity of the vehicle. The acceleration sensor 115 further detects the rotational angular velocity about each of these axes, that is, the change rate of the roll angle of the vehicle (rolling angular velocity), the change rate of the pitch angle (pitching angular velocity), and the change rate of the yaw angle (yawing angular velocity). Based on the acceleration detected by the acceleration sensor 115, the moving direction of the vehicle can be detected, and the direction of the vehicle can also be detected.

[0028] The steering angle sensor 116 detects the operation amount of the steering wheel by the driver, that is, the steering angle of the vehicle. Based on the steering angle detected by the steering angle sensor 116, the direction of the steering wheel, that is, the steering direction of the vehicle, can be detected. Specifically, when the steering wheel is operated clockwise, the steering direction in which the vehicle turns is defined as the right direction, and when the steering wheel is operated counterclockwise, the steering direction in which the vehicle turns is defined as the left direction.

[0029] The vehicle speed sensor 117 detects the traveling speed of the vehicle (hereinafter referred to as "vehicle speed"). The vehicle speed can be calculated by converting the wheel speed detected by the wheel speed sensor 113 based on the tire dynamic radius or the like, and can also be calculated by converting the rotational speed of the output shaft of the drive source based on the gear ratio and the tire dynamic radius in the power transmission path.

[0030] (Internal configuration of the controller) FIG. 3 is a schematic diagram showing the internal configuration of the controller 101.

[0031] The controller 101 includes, as its internal configuration, an inclined road detection unit B111, a wheel lock detection unit B112, a vehicle state determination unit B113, a basic brake hydraulic pressure setting unit B114, a deceleration determination unit B115, and a brake hydraulic pressure adjustment control unit B116. These various internal configurations are realized software-wise by the central processing unit (CPU) of the controller 101 operating according to a control program stored in advance in a storage unit such as a ROM.

[0032] The inclined road detection unit B111 detects that the vehicle is on an inclined road based on the output signal from the inclination angle sensor 114.

[0033] The wheel lock detection unit B112 detects that the vehicle is in a wheel lock state based on the output signals from the wheel speed sensors 113 (113a to 113d). In the present embodiment, the wheel lock state means that all the wheels provided on the vehicle are in a locked state. That the vehicle is in a wheel lock state can be detected by the fact that there is no substantial difference in wheel speed between different wheels while the brake pedal is depressed, and can also be detected by the fact that the wheel speed of each wheel is substantially 0 [rpm].

[0034] The vehicle state determination unit B113 detects that the vehicle has started moving on an inclined road in a wheel-locked state, that is, that the vehicle has slipped, and determines whether or not the moving direction of the vehicle coincides with or is in line with the steering direction after the start of movement in the wheel-locked state. This series of determinations can be carried out based on the detection results of the inclined road detection unit B111 and the wheel lock detection unit B112, as well as the output signals from the acceleration sensor 115 and the steering angle sensor 116. The moving direction of the vehicle can be detected based on the output signal from the acceleration sensor 115, and the steering direction of the vehicle can be detected based on the output signal from the steering angle sensor 116. In the present embodiment, in a situation where the vehicle is slipping on an inclined road, when the moving direction of the vehicle deviates from the direction in which the wheels face from the inclination direction of the road surface, that is, the steering direction, it is determined that the moving direction of the vehicle coincides with the steering direction.

[0035] The basic brake hydraulic pressure setting unit B114 calculates a basic value of the brake hydraulic pressure (hereinafter referred to as "basic brake hydraulic pressure") BRKb based on the output signal from the brake pedal force sensor 112. The basic brake hydraulic pressure BRKb is calculated as a larger value as the brake operation amount is larger.

[0036] The deceleration determination unit B115 determines whether or not the vehicle is decelerating, in other words, whether or not a deceleration in the moving direction has occurred in the vehicle, based on the output signal from the acceleration sensor 115.

[0037] The brake hydraulic pressure adjustment control unit B116 adjusts the brake hydraulic pressure BRKf of the front brake 15 based on the determination results of the vehicle state determination unit B113 and the deceleration determination unit B115. Specifically, in the situation where the vehicle is sliding down an inclined road, when the moving direction of the vehicle does not match the steering direction, the brake hydraulic pressure BRFf is reduced below the basic brake hydraulic pressure BRKb, while when the moving direction of the vehicle matches the steering direction, the reduction of the brake hydraulic pressure BRKf is stopped. In this embodiment, when reducing the pressure, the brake hydraulic pressure BRKf is reduced by a predetermined pressure ΔBRK from the basic brake hydraulic pressure BRKb (BRKf = BRKb - ΔBRK). The brake hydraulic pressure adjustment control unit B116 continues the brake hydraulic pressure adjustment control until a deceleration occurs in the vehicle. The brake hydraulic pressure adjustment control unit B116 outputs a command signal corresponding to the adjusted brake hydraulic pressure BRKf or the pressure reduction value ΔBRK of the brake hydraulic pressure BRKf according to the brake hydraulic pressure adjustment control to the pressure adjustment valve 17.

[0038] (Content of braking control) FIG. 4 is a flowchart showing the overall flow of the control (braking control) implemented by the controller 101, and FIG. 5 is a flowchart showing the specific content of the brake hydraulic pressure adjustment process (S107) in the braking control. The controller 101 implements the controls shown in FIGS. 4 and 5 at predetermined time intervals after the power supply to the control system is turned on.

[0039] In the flowchart shown in FIG. 4, in S101, output information from various sensors such as the brake operation amount and the wheel speed is acquired.

[0040] In S102, it is determined whether the vehicle is on an inclined road. If the vehicle is on an inclined road, the process proceeds to S103; if not, the current control is terminated.

[0041] In S103, it is determined whether the vehicle is stopped. If the vehicle is stopped, the process proceeds to S104; if not, the current control is terminated.

[0042] In S104, it is determined whether the brake pedal is depressed by the driver. If the brake pedal is depressed, that is, when the brakes are on, the process proceeds to S105. If the brake pedal is not depressed, that is, when the brakes are off, the current control is terminated.

[0043] In S105, the basic brake hydraulic pressure BRKb is set. As a result, brake oil with the basic brake hydraulic pressure BRKb is supplied to the brake calipers 152 and 162 of both the front brake 15 and the rear brake 16, and braking force by the foot brake is generated on the vehicle via both the front and rear wheels.

[0044] In S106, it is determined whether the vehicle has started to move, in other words, whether a slip has occurred on the vehicle. If the vehicle has started to move, the process proceeds to S107. If the vehicle continues to be stationary, the process returns to S104, and the processes from S104 to S106 are repeatedly executed.

[0045] In S107, brake hydraulic pressure adjustment control is carried out. The brake hydraulic pressure adjustment control is based on the procedure shown in the flowchart of FIG. 5.

[0046] In the flowchart shown in FIG. 5, in S201, it is determined whether the vehicle is in a wheel lock state. If the vehicle is in a wheel lock state, the process proceeds to S202. If it is not in a wheel lock state, the brake hydraulic pressure adjustment control is terminated and the current control is terminated.

[0047] In S202, the steering direction of the vehicle is detected.

[0048] In S203, the moving direction due to the slip of the vehicle, that is, the slip direction of the vehicle, is detected.

[0049] In S204, it is determined whether the moving direction of the vehicle coincides with the steering direction. If the moving direction of the vehicle coincides with the steering direction, the process proceeds to S205; if not, the process proceeds to S206. In the present embodiment, when the acceleration of the vehicle is directed in the slope direction of the road surface, it is determined that the moving direction of the vehicle does not coincide with the steering direction, and when the acceleration of the vehicle is directed in a direction deviating from the steering direction with respect to the slope direction of the road surface, it is determined that the moving direction of the vehicle coincides with the steering direction. In addition to or instead of such determination, an angle formed by the moving direction of the vehicle with respect to the slope direction of the road surface is detected, and when this angle coincides with a determination value corresponding to the steering angle of the vehicle or falls within a predetermined range based on the determination value, it may be determined that the moving direction of the vehicle coincides with the steering direction.

[0050] In S205, the brake hydraulic pressure BRKf of the front brake 15 is set to the basic brake hydraulic pressure BRKb.

[0051] In S206, the brake hydraulic pressure BRKf of the front brake 15 is set to a pressure reduced by a predetermined pressure ΔBRK from the basic brake hydraulic pressure BRKb. In the present embodiment, among the front wheels and the rear wheels, only the pressure of the brake oil supplied to the brake caliper 152 of the front wheels, which are the steered wheels, that is, the brake hydraulic pressure BRKf of the front brake 15, is reduced, and the pressure of the brake oil supplied to the brake caliper 162 of the rear wheels is maintained at the basic brake hydraulic pressure BRKb. By reducing the pressure of the brake oil supplied to the front brake caliper 152, the release of the wheel lock state is promoted.

[0052] In S207, it is determined whether the vehicle is decelerating. If the vehicle is decelerating, the brake fluid pressure adjustment control is terminated and the current control is ended. On the other hand, if the vehicle is not decelerating, the process returns to S202 to continue the brake fluid pressure adjustment control. That is, in the present embodiment, after the vehicle starts to move on the inclined road in a wheel-locked state, the brake fluid pressure adjustment control is continued until a deceleration occurs in the vehicle, and the brake fluid pressure BRKf is decreased according to whether the moving direction of the vehicle coincides with or does not coincide with the steering direction (S206), and the control to stop the pressure reduction of the brake fluid pressure BRKf (S205) is repeatedly executed.

[0053] FIG. 6 is an explanatory diagram showing the behavior of a vehicle by braking control.

[0054] In FIG. 6, vehicles V21 and V22 show the behavior after the parked vehicle V1 starts to move in a wheel-locked state. It is assumed that the vehicle V21 moves along the path R1 in the inclined direction of the road surface after the start of movement, and the vehicle V22 moves along the path R2 in a direction deviating from the inclined direction of the road surface after the start of movement. The vehicle V21 moving along the path R1 has an acceleration in the inclined direction of the road surface and is in a state where the moving direction does not coincide with the steering direction. The vehicle V22 moving along the path R2 has an acceleration A2 in a direction deviating from the inclined direction of the road surface to the steering direction and is in a state where the moving direction coincides with the steering direction.

[0055] In the present embodiment, in a situation where the vehicle is sliding on the inclined road, the vehicle V21 is targeted for pressure reduction by the brake fluid pressure adjustment control, while the pressure reduction for the vehicle V22 is stopped. That is, like the vehicle V21, although rotation about the yaw axis occurs in the vehicle and a change corresponding to the steering occurs in the direction of the vehicle, when the vehicle is still moving in the inclined direction of the road surface, the pressure reduction by the brake fluid pressure adjustment control is performed. On the other hand, like the vehicle V22, when not only a change occurs in the direction of the vehicle but also the moving direction of the vehicle deviates from the inclined direction of the road surface and the moving direction coincides with the steering direction, the pressure reduction by the brake fluid pressure adjustment control is stopped.

[0056] Figure 7 is a state transition diagram showing the operating state of the braking device 1 switched by braking control and the switching conditions (transition conditions). With reference to Figure 7, the operation of the braking device 1 will be described.

[0057] The operating state of the braking device 1 is roughly classified into the following three states A to C. State A: The state where the vehicle is stopped State B: The state where the vehicle is sliding and the moving direction of the vehicle coincides with the steering direction State C: The state where the vehicle is sliding and the moving direction of the vehicle does not coincide with the steering direction In state A, the brake hydraulic pressure adjustment control is stopped. In state B, the reduction of the brake hydraulic pressure for the steering wheels (front wheels) is stopped. In state C, the brake hydraulic pressure of the steering wheels (front wheels) is reduced.

[0058] The transition from state A to state B occurs when the following transition condition 1 is satisfied. (Transition condition 1) · The brake hydraulic pressure adjustment control is stopped. · The wheel lock state is detected. · The start of sliding, that is, the acceleration in the inclined direction of the road surface is detected. · The moving direction of the vehicle coincides with the steering direction.

[0059] The transition from state A to state B occurs when the following transition condition 2 is satisfied. (Transition condition 2) · The brake hydraulic pressure adjustment control is stopped. · The wheel lock state is detected. · The start of sliding, that is, the acceleration in the inclined direction of the road surface is detected. · The moving direction of the vehicle does not coincide with the steering direction.

[0060] The transition from state B to state C occurs when the following transition condition 3 is satisfied. (Transition condition 3) · Performing brake hydraulic pressure adjustment control · Detecting the wheel locked state · Not detecting the deceleration after the start of slipping · The moving direction of the vehicle not matching the steering direction

[0061] The transition from state C to state B occurs when the following transition condition 4 is satisfied. (Transition condition 4) · Performing brake hydraulic pressure adjustment control · Lowering the brake hydraulic pressure of the steering wheel · Not detecting the deceleration after the start of slipping · The moving direction of the vehicle matching the steering direction

[0062] The transition from state B to state A occurs when the following transition condition 5 is satisfied. (Transition condition 5) · Performing brake hydraulic pressure adjustment control · Detecting the wheel locked state · Detecting the deceleration after the start of slipping · The moving direction of the vehicle matching the steering direction

[0063] The transition from state C to state A occurs when the following transition condition 6 is satisfied. (Transition condition 6) · Performing brake hydraulic pressure adjustment control · Lowering the brake hydraulic pressure of the steering wheel · Detecting the deceleration after the start of slipping · The moving direction of the vehicle not matching the steering direction

[0064] (Explanation of the function and effect) The braking device 1 of the vehicle according to the present embodiment has the above configuration. Hereinafter, the effects obtained by the present embodiment will be described.

[0065] First, after the vehicle starts moving on an inclined road with the wheels in a locked state, that is, after the vehicle has slipped, if the moving direction of the vehicle does not coincide with the steering direction, in other words, if the vehicle is sliding down in a direction different from the driver's intention, the brake hydraulic pressure of the vehicle is reduced by brake hydraulic pressure adjustment control to promote the release of the wheel locked state. Thereby, the driver's steering ability can be restored, and the vehicle can be directed in the direction intended by the driver.

[0066] In this way, when the vehicle slips due to wheel slippage on an inclined road, it is possible to avoid the situation where the vehicle continues to slide in a direction different from the driver's intention, and it is possible to further improve safety.

[0067] On the other hand, when the moving direction of the vehicle coincides with the steering direction, in other words, when the vehicle is sliding down the inclined road but has not lost its steering ability, by stopping the pressure reduction by brake hydraulic pressure adjustment control, it is possible to avoid a situation where the deceleration or stop of the vehicle is delayed due to an unnecessary decrease in the brake hydraulic pressure and the safety is impaired.

[0068] Second, when at least the front wheels are the steering wheels among the front and rear wheels, by making the object of implementing the brake hydraulic pressure adjustment control only the front wheels among the front and rear wheels, it is possible to promote the release of the locked state of the wheels directly affecting steering and restore the steering ability, while avoiding a situation where the braking of the vehicle is hindered by the decrease in the brake hydraulic pressure for both the front and rear wheels.

[0069] Furthermore, by making the object of implementing the brake hydraulic pressure adjustment control only the front wheels, it is possible to accurately detect that the wheel locked state has been released and implement the brake hydraulic pressure adjustment control more appropriately.

[0070] Specifically, when detecting the occurrence of a wheel lock state based on the rotational difference between wheels, by maintaining the brake hydraulic pressure for the rear wheels, it is possible to form a rotational difference between the front wheels and the rear wheels, and by detecting this rotational difference, it is possible to detect that the wheel lock state has been released. On the other hand, when performing brake hydraulic pressure adjustment control for both the front wheels and the rear wheels, even if the wheel lock state is released, a rotational difference cannot be detected, so it is impossible to detect the release of the wheel lock state, and the brake hydraulic pressure adjustment control will continue unnecessarily.

[0071] And when the rear wheels are provided on both the left and right sides, by maintaining the brake hydraulic pressure for both the left and right rear wheels, it is possible to avoid a situation where the braking force by the rear wheels is biased left and right.

[0072] Thirdly, when a deceleration occurs in the vehicle after the implementation of the brake hydraulic pressure adjustment control, by stopping the brake hydraulic pressure adjustment control, the brake hydraulic pressure is increased, and braking force is applied by both the front wheels and the rear wheels, making it possible to quickly decelerate and stop the vehicle.

[0073] Fourthly, when the vehicle starts to move from a stopped state in a wheel lock state, by implementing the brake hydraulic pressure adjustment control, it is possible to suppress the situation where the vehicle continues to slide in a direction different from the driver's intention due to slipping from the stopped state. Specifically, even though the driver is turning the steering wheel to the right or left, the vehicle continues to slide straight down the inclined road.

[0074] Fifthly, when detecting the case where all the wheels of the vehicle are in a locked state as the wheel lock state, and when the vehicle starts to move on an inclined road in such a wheel lock state, by implementing the brake hydraulic pressure adjustment control, it is possible to avoid a situation where unnecessary pressure reduction by the brake hydraulic pressure adjustment control hinders braking in a situation where only some of the wheels are in a locked state. For example, in the case of movement when only the front wheels are in a locked state among the front wheels and the rear wheels, and it is possible to quickly decelerate and stop the vehicle.

Explanation of Signs

[0075] 1…Vehicle braking device, 11…Brake pedal, 12…Brake booster, 13…Brake master cylinder, 14…Brake oil reservoir, 15…Front brake, 151…Brake disc, 152…Brake caliper, 152a…Brake pad, 16…Rear brake, 161…Brake disc, 162…Brake caliper, 162a…Brake pad, 17…Pressure regulating valve, 101…Controller, 111…Accelerator opening sensor, 112…Brake pedal force sensor, 113…Wheel speed sensor, 114…Inclination angle sensor, 115…Acceleration sensor, 116…Steering angle sensor, 117…Vehicle speed sensor, S…Control system.

Claims

1. An inclined road detection means for detecting that the vehicle is on an inclined road; A wheel lock detection means for detecting that the vehicle is in a wheel lock state; A vehicle state determination means for determining whether the moving direction of the vehicle on the inclined road coincides with the steering direction; A brake hydraulic pressure setting means for setting the brake hydraulic pressure of the vehicle according to the driver's brake operation, and comprising: After the vehicle starts to move on the inclined road in the wheel lock state, while the vehicle is moving on the inclined road, when the moving direction of the vehicle does not coincide with the steering direction, the brake hydraulic pressure setting means reduces the brake hydraulic pressure below the basic value according to the driver's brake operation, while when the moving direction of the vehicle coincides with the steering direction, the brake hydraulic pressure setting means performs a brake hydraulic pressure adjustment control to stop the decompression of the brake hydraulic pressure. A braking device for a vehicle.

2. The vehicle includes front wheels and rear wheels, When the brake hydraulic pressure setting means uses at least the front wheels among the front wheels and the rear wheels as steerable wheels that can be turned according to the driver's steering, the brake hydraulic pressure adjustment control is performed only on the front wheels among the front wheels and the rear wheels. The braking device for a vehicle according to Claim 1.

3. The vehicle further includes a deceleration determination means for determining whether the vehicle is decelerating, When it is determined by the deceleration determination means that the vehicle is decelerating after the brake hydraulic pressure adjustment control is performed, the brake hydraulic pressure setting means stops the brake hydraulic pressure adjustment control. The braking device for a vehicle according to Claim 1.

4. When the vehicle starts to move in the wheel lock state from a stopped state, the brake hydraulic pressure setting means performs the brake hydraulic pressure adjustment control. The braking device for a vehicle according to Claim 1.

5. The wheel lock detection means detects that the vehicle is in the wheel lock state when all wheels of the vehicle are in the locked state. The braking device for a vehicle according to any one of Claims 1 to 4.

6. An inclined road detection means for detecting that the vehicle is on an inclined road; A wheel lock detection means for detecting that the vehicle is in a wheel lock state; A vehicle state determination means for determining whether the moving direction of the vehicle on the inclined road coincides with the steering direction; A brake hydraulic pressure setting means for setting the brake hydraulic pressure of the vehicle, and comprising: The brake hydraulic pressure setting means is a braking device for a vehicle that sets a lower brake hydraulic pressure when the moving direction of the vehicle does not match the steering direction while the vehicle is moving on the inclined road, after the vehicle starts moving on the inclined road in a wheel-locked state, than when the moving direction of the vehicle matches the steering direction.

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