JP2003154931A - Brake fluid pressure control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake fluid pressure control device capable of eliminating the occurrence of the stroke loss of a brake piston when a brake pressure is increased by preventing the brake piston from being moved by a lateral acceleration and increasing a control responsiveness by preventing brake pressure rise characteristics from being deteriorated. SOLUTION: This brake fluid pressure control device comprises a backward movement stop control means 23. In the backward movement stop means, when the possibility of instable running is judged to be increased by an instable running estimation means 23 and a pressure increasing control valve 5b on the other wheel side in the same system as a second channel circuit 2 for closing an out side gate valve 3 is in non-pressure increasing control state, the out side gate valve 3 is closed before a control by an instable running avoidance control means 22 is started, and the pressure increasing control valve 5b on the other wheel side in the same system as the second channel circuit 2 for closing the out side gate valve 3 to stop that the brake piston 33 of a wheel cylinder WCFR for a right front wheel is moved backward in a direction apart from a rotor 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking force of each wheel for the purpose of, for example, preventing wheel lock, preventing wheel spin of a driving wheel at the time of acceleration, assisting braking force, and ensuring stability of vehicle posture. TECHNICAL FIELD The present invention relates to a brake fluid pressure control device capable of variably controlling a brake, and particularly to a technique for improving control responsiveness.

[0002]

2. Description of the Related Art In recent years, a variety of functions for variably controlling the brake fluid pressure of each wheel have been added to a brake device installed in a vehicle. For example, an anti-skid control device (AB) that prevents the wheels from being locked on a low μ road or the like to reduce the braking distance while keeping the vehicle behavior stable.
S), a traction control device (TCS) that prevents wheel spin of the drive wheels during acceleration of the vehicle, or when the brake pressure operated by the driver is insufficient, the insufficient brake pressure is supplied to the wheel cylinders. Braking force assist device configured to operate, and vehicle behavior control that secures vehicle running stability by applying braking force to wheels regardless of whether the driver operates the brakes to eliminate oversteer or understeer of the vehicle Device (VD
C) etc. Particularly, in this vehicle behavior control device, even if the driver does not operate the brake, when the possibility of oversteering or understeering occurs in the vehicle, the brake pressure of each wheel cylinder is automatically adjusted to prevent oversteering or understeering. A lateral force that opposes the understeer is generated in the vehicle.

[0003]

However, when the vehicle is turning, particularly when the vehicle is oversteering, a relatively large lateral acceleration is generated in the vehicle. As shown in FIG. 5 (a cross-sectional view showing the brake caliper portion), this lateral acceleration also affects the wheel cylinders of the respective wheels, and, for example, lateral acceleration occurs on the brake piston 33 side around the rotor 31. in case of,
The brake piston 33 moves in the direction away from the rotor 31. Therefore, the brake piston 33 may be in a state of moving in the direction to release the braking force.

Such a phenomenon is apt to occur especially when the driver does not perform a braking operation, that is, when the hydraulic pressure in the wheel cylinder is in the atmospheric pressure state. When an attempt is made to increase the brake pressure from the state in which 33 moves in the brake release direction, stroke loss is caused by the amount of the brake piston 33 moving in the brake release direction, which deteriorates the boosting characteristic. As indicated by the dotted line, there is a problem that a delay may occur before the start of pressure increase (generation of braking force).

In particular, since the vehicle behavior control device is intended to stabilize the behavior of the vehicle, it has to react to the behavior of the vehicle within a very short time. In other words, unlike the anti-skid control device, it is required to perform braking in an extremely short time,
The delay in boosting pressure adversely affects the stability of vehicle behavior.

The present invention has been made in view of the above-mentioned conventional problems, and prevents the movement of the brake piston due to the lateral acceleration generated in the vehicle to prevent the straw of the brake piston from increasing when the brake pressure is increased. An object of the present invention is to provide a brake fluid pressure control device capable of eliminating the occurrence of cross, thereby preventing deterioration of the brake pressure boosting characteristic and enhancing control response.

[0007]

In order to achieve the above-mentioned object, a brake fluid pressure control device according to claim 1 of the present invention comprises:
A master cylinder that generates hydraulic pressure in response to the driver's braking operation, and a brake pad that is arranged so as to face the rotor that rotates integrally with the wheels are introduced by a brake piston that operates in the axial direction of the wheel rotation axis by the hydraulic pressure. A wheel cylinder that generates a braking force by pressing, a main circuit connecting the wheel cylinder and the master cylinder,
A normally open pressure increasing control valve for opening and closing the main circuit, a normally open outside gate valve for opening and closing the main circuit between the pressure increasing control valve and the master cylinder, and a hydraulic pressure for the wheel cylinder. Is connected to the main circuit between the out-side gate valve and the pressure increase control valve, and the suction circuit is connected to the master cylinder and A hydraulic pump connected to a reservoir for supplying pressurized hydraulic pressure to the main circuit side, a normally open inside gate valve for opening and closing the suction circuit, the pressure increasing control valve, the pressure reducing control valve and both gates. In a brake fluid pressure control device including brake fluid pressure control means for controlling valve operation and hydraulic pump drive, an unstable traveling state detection for detecting an unstable traveling state based on lateral acceleration acting on a vehicle means When the unstable traveling state is detected by the unstable traveling state detecting means, the out side gate valve of at least one wheel is closed so as to oppose the lateral acceleration generated in the vehicle, and the hydraulic pump is operated. There is a possibility of unstable traveling based on the unstable traveling avoidance control means for driving and supplying the pressurized hydraulic pressure to the wheel cylinder of the wheel and the unstable traveling state detection value detected by the unstable traveling state detecting means. Unstable driving estimation means for judging whether or not the driving has increased, and when the unstable driving estimation means judges that the possibility of unstable driving has increased, the out side prior to the start of control of the unstable driving avoiding control means. A reverse prevention control means for preventing the brake piston of the wheel cylinder from retracting in the direction away from the rotor by closing the gate valve; It was.

According to a second aspect of the present invention, there is provided the brake fluid pressure control device according to the first aspect of the present invention.
A main circuit of two systems branched to two wheels on the left and right by pipes or X pipes is provided, the outside gate valve is provided in the main circuit of each system, and pressure increase control of each wheel is provided in each branch circuit. A valve is provided, the reverse movement prevention control means determines that the unstable traveling possibility is increased by the unstable traveling estimating means, and the other wheel side of the same system as the main circuit that closes the outside gate valve When the pressure increase control valve is controlled to open, the outside gate valve is closed prior to the control of the unstable running avoidance control means, and the other wheel of the same system as the main circuit that closes the outside gate valve is closed. By closing the pressure-increasing control valve on the side, the means for preventing the brake piston of the wheel cylinder from retreating in the direction away from the rotor is adopted.

[0009]

In the brake fluid pressure control device according to the first aspect of the present invention, in the unstable traveling estimating means, there is a possibility of unstable traveling based on the unstable traveling state detection value detected by the unstable traveling state detecting means. When it is determined whether or not the possibility of unstable traveling has increased, it is determined that the reverse prevention control means controls the closing of the out side gate valve before the control of the unstable traveling avoidance control means is started. This prevents the brake piston from retreating in the direction away from the rotor due to the lateral acceleration generated in the vehicle. Since the stroke loss of the piston is eliminated, the deterioration of the brake pressure boosting characteristic can be prevented and the control response can be improved. That.

In the brake fluid pressure control device according to the second aspect of the invention, as described above, two main circuits of the two systems are provided, each branching to two wheels on the left and right by the H pipe or the X pipe, and the main circuit of each system. In the case where each of the out-side gate valves is provided in and each of the branch circuits is provided with the pressure increase control valve for each wheel, it is determined that the unstable traveling has increased the possibility of unstable traveling, and ,
When the other wheel side of the same system as the main circuit that closes the out side gate valve is in the non-pressure increasing control state, the reverse gate preventing control means controls the out side gate before starting the control of the unstable traveling avoiding control means. By closing the valve, and by closing the pressure-increasing control valve on the other wheel side of the same system as the main circuit that closes the out-side gate valve, the other pressure-increasing control valve on the other wheel side of the same system is closed. By letting the hydraulic pressure escape to the wheel cylinder side of the wheel, it is possible to prevent the brake piston of the wheel cylinder on the control start side wheel by the unstable running avoidance control means from retreating in the direction away from the rotor. . That is, the state where the brake piston on the other wheel side of the same system is moving in the direction away from the rotor due to lateral acceleration,
Even if the rotor and the brake piston are separated from each other by the amount of eccentricity of the rotor, the hydraulic pressure is applied to the wheel cylinder side of the other wheel by closing the pressure increase control valve on the other wheel side of the same system. Can be prevented from escaping.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of a brake fluid pressure control device according to an embodiment of the present invention. In the figure, WCFR is a wheel cylinder for the right front wheel, WCRL is a wheel cylinder for the left rear wheel, and MC is each wheel cylinder WC.
It is a master cylinder as a hydraulic pressure source that supplies to FR and WCRL. The master cylinder MC has a first channel circuit 1 that constitutes a main circuit connected to wheel cylinders on the left front wheel and right rear wheels (not shown) in conjunction with the depression of the brake pedal BP, the right front wheel, X-piped 2 with the second channel circuit 2 that constitutes the main circuit connected to the wheel cylinders WCFR and WCRL on the left rear wheel side
It is configured to generate system brake fluid pressure.
Incidentally, the master cylinder MC is provided with a reservoir tank RT for storing the working fluid.

In the following description, since the configurations of both channel circuits 1 and 2 are the same, only the configuration of the second channel circuit 2 will be described below. The second
The channel circuit 2 is the wheel cylinder WCFR for the right front wheel.
To a front wheel branch circuit 2a and a rear wheel branch circuit 2b to a wheel cylinder WCRL for the left rear wheel.

An out-side gate valve 3 is provided upstream of the second channel circuit 2. The out-side gate valve 3 is constituted by a normally open 2-port 2-position electromagnetic switching valve that opens the second channel circuit 2 by a spring force when it is not operated and shuts off the second channel circuit 2 when it is operated. . Also, this out side gate valve 3
From the master cylinder MC side to the wheel cylinders WCFR, WCRL side (hereinafter, the side relatively close to the master cylinder MC is referred to as upstream, and the side close to the wheel cylinders WCFR, WCRL is downstream. A one-way valve 2d is provided to allow only circulation.

Each of the branch circuits 2a and 2b is provided with pressure increasing control valves 5a and 5b and pressure reducing control valves 6a and 6b for reducing, maintaining and increasing the brake fluid pressure of the wheel cylinders WCFR and WCRL. There is. That is, the pressure-increasing control valves 5a, 5b are provided in the middle of the branch circuits 2a, 2b, and the branch circuits 2a, 2b are brought into communication with each other by the spring force when the branch circuits 2a, 2b are not activated, and the branch circuits 2a, 2b are activated when they are activated.
It is composed of a normally open 2-port 2-position electromagnetic switching valve that shuts off 2b. Further, the pressure reducing control valve 6a,
6b is a pressure increasing control valve 5a of each of the branch circuits 2a and 2b,
Downstream of 5b (wheel cylinders WCFR, WCRL side)
It is normally provided in the middle of the discharge circuit (drain circuit) 8 that branches from the branch points 2e, 2e provided to the reservoir 7 and reaches the reservoir 7, and shuts off the discharge circuit 8 when it is not operating and connects the discharge circuit 8 when it is operating. It is composed of a closed 2-port 2-position electromagnetic switching valve. In addition, each branch circuit 2a, 2b
Is provided with bypass circuits 2f, 2f having one-way valves 2g, 2g that bypass the pressure increase control valves 5a, 5b and allow only flow from downstream to upstream in the middle.

A hydraulic pump 4 for supplying a pressurized hydraulic pressure to the wheel cylinders WCFR and WCRL is also provided. That is, in the hydraulic pump 4, the suction circuit 4a is connected to the reservoir 7 and the reservoir tank RT, while the discharge circuit 4b is provided between the out-side gate valve 3 and the branch circuits 2a and 2b. Connected to the connection point 2h.

An in-side gate valve 9 is provided in the middle of the suction circuit 4a. This inside gate valve 9
Is a normally-closed 2-port 2-position electromagnetic switching valve that shuts off the suction circuit 4a by a spring force when it is not operating and connects the suction circuit 4a when it is operating. The suction circuit 4 between the hydraulic pump 4 and the reservoir 7
A valve 4c is provided at a so that it can only flow in the direction of the hydraulic pump 4.

The wheel cylinders WCFR and WCRL are
As shown in FIG. 5, the brake pads 32a and 32b arranged to face the rotor 31 rotating integrally with the wheels are
With the brake cylinder 33 that operates in the axial direction of the rotation axis of the wheel based on the master cylinder hydraulic pressure generated in the master cylinder MC based on the driver's brake operation or the discharge hydraulic pressure (pressurized hydraulic pressure) of the hydraulic pump 4. Braking force is generated by pressing.

Each valve 3, 5a, 5b, 6 of the solenoid valve structure
The operations of a, 6b and 9 are controlled by a control unit (brake hydraulic pressure control means) not shown. That is, the control unit includes a wheel speed sensor that detects the rotational speed of the wheels (not shown), a yaw rate sensor that detects the yaw rate of the vehicle body, a steering angle sensor that detects the steering angle of the vehicle, and whether or not the vehicle is in a brake operation state. A signal from a sensor group such as a brake sensor is input, and the control unit obtains the slip ratio of the wheels based on the signals input from these sensor groups, and when the slip ratio exceeds a predetermined value during braking, this slip ratio is determined. The ABS control to reduce the speed, the TCS control to suppress the drive wheel slip when non-braking occurs, and the braking force to some wheels to eliminate the oversteer or understeer of the vehicle to improve the running stability of the vehicle. The vehicle behavior control (VDC control) to ensure is performed.

Next, the operation of the brake fluid pressure control device according to the embodiment of the present invention will be described. Since the operations of the first and second channel circuits 1 and 2 are the same in this operation, only the second channel circuit 2 will be described. Further, the ABS control is not a main element of the present invention, and therefore its explanation is omitted.

When the slip ratio of the drive wheels becomes high due to sudden start / acceleration, control (TCS control) is performed to keep the slip ratio within a predetermined range, or the posture of the vehicle is likely to be disturbed. In order to perform stable control such that the posture of the vehicle is controlled in the stable direction by the braking force (VDC control), the control unit first controls the pressure increase of some wheels as shown in FIG. Is done.

In this pressure increase control, the motor M of the hydraulic pump 4 is driven and the in-side gate valve 9 and the out-side gate valve 3 are energized. Therefore, the out-side gate valve 3 is closed and the second channel circuit 2 is shut off at that position, and the in-side gate valve 9 is opened so that the suction circuit 4a is communicated. Therefore, the hydraulic pump 4 passes through the suction circuit 4a as shown by the white arrow, and the master cylinder M
As a result of sucking the hydraulic fluid in C or the reservoir tank RT and discharging the pressurized hydraulic pressure to the discharge circuit 4b, the normally open pressure increasing control valve 5a provided in both branch circuits 2a and 2b as indicated by the black arrow. Wheel cylinders WCFR, WC via 5b
The pressure of RL is increased and the braking force can be generated.
At this time, for example, the wheel cylinder WC of the left rear wheel
If the RL does not want to perform pressure increase control (during non-pressure increase control), the branch circuit 2b is energized by energizing the normally open pressure increase control valve 5b.
Shut off the side.

Next, in the holding control, as shown in FIG. 2, the in-side gate valve 9 and the out-side gate valve 3 are energized from the pressure increasing control state. As a result, both gate valves 9 and 3 are closed and the suction circuit 4a and the second channel circuit 2 are shut off. Therefore, the hydraulic pressure of the wheel cylinder WCFR of the right front wheel whose pressure has been increased is maintained. In this holding control, the motor M of the hydraulic pump 4 remains in the driving state, but since the suction circuit 4a is shut off by closing the in-side gate valve 9, the pressurized hydraulic pressure from the hydraulic pump is increased. It is never discharged.

Next, in the pressure reducing control, as shown in FIG. 3, only the outside gate valve 3 is energized from the holding control state. As a result, the outside gate valve 3 is opened and the second channel circuit 2 is opened. Therefore, the hydraulic fluid in the wheel cylinder WCFR of the right front wheel is normally opened and the pressure increase control valve 5 is opened.
The pressure is reduced by being discharged to the master cylinder MC or the reservoir tank RT via a and the out side gate valve 3.

As described above, by controlling the opening / closing of the in-side gate valve 9 and the out-side gate valve 3, the wheel cylinder hydraulic pressure of the desired wheel is increased / retained / reduced to generate a desired braking force. As a result, it is possible to generate a yam moment in the vehicle body to control the vehicle attitude and avoid an unstable traveling state. By the way, as an example of vehicle behavior control (VDC) for avoiding this unstable running state, a yaw moment in the understeer direction is generated by applying a braking force to the front wheel of the outer turning wheel during oversteer, and the inner wheel turning during understeer. It is possible to control the vehicle attitude in a stable direction by applying a braking force to the rear wheels to generate a yaw moment in the oversteer direction.

Next, the content of the knockback control during the vehicle behavior control will be described with reference to FIGS. Knockback control refers to control for preventing movement of the brake piston due to lateral acceleration generated in the vehicle, as described in the problem to be solved by the invention. First,
In the block diagram showing the contents of the knockback control of FIG. 4, 21 is an unstable traveling state detecting means, 22 is an unstable traveling avoiding controlling means, 23 is an unstable traveling estimating means, and 24 is a reverse stopping control means. , These means are integrated in the control unit.

The unstable running state detecting means 21 detects an unstable running state based on the lateral acceleration acting on the vehicle. In the embodiment of the present invention, the yaw rate actually acting on the vehicle is detected. An actual yaw rate calculation means 211 for calculating, a target yaw rate calculation means 212 for calculating a target yaw rate at which the vehicle can travel stably, a target yaw rate calculated by the target yaw rate calculation means 212 and the actual yaw rate calculation means 211. The difference value calculating means 213 calculates a yaw rate value corresponding to the difference between the calculated actual yaw rate and the unstable running state detection value.

The unstable traveling avoidance control means 22 is arranged so as to oppose the lateral acceleration generated in the vehicle in accordance with the unstable traveling state detection value detected by the unstable traveling state detecting means 21. The discharge hydraulic pressure from the hydraulic pump 4 is supplied to the wheel cylinder of one wheel (the wheel cylinder WCFR of the right front wheel in the embodiment of the present invention) to generate a braking force.

The unstable traveling estimating means 23 determines whether or not the possibility of unstable traveling is increased based on the unstable traveling state detection value detected by the unstable traveling state detecting means 21, In addition, the reverse prevention control means 24
Prevents the brake piston 33 of the wheel cylinder WCFR of the right front wheel from retreating in a direction away from the brake pad 32b when the unstable traveling estimating means 23 determines that the possibility of unstable traveling has increased. Control, so-called knockback control, is performed. In the embodiment of the present invention, control for holding the brake fluid pressure of the right front wheel cylinder WCFR is performed as knockback control.

Next, the content of the knockback control will be described with reference to the flowchart of FIG. 6 and the time chart of FIG. In the embodiment of the present invention, VD
A case where a braking force is applied to the right front wheel in C control will be described.

First, step S in the flowchart of FIG.
In 101, the actual yaw rate calculating means 211 calculates the actual yaw rate YAW actually acting on the vehicle based on the signal from the yaw rate sensor, and the following step S
At 102, in the target yaw rate calculation means 212,
Based on the signal from the steering angle sensor, a target yaw rate TYAW with which the vehicle can travel stably is calculated.

In the following step S103, the target yaw rate TYAW calculated as described above is expressed by the following equation.
The yaw rate difference ΔYAW corresponding to the absolute value of the difference between the actual yaw rate YAW and the actual yaw rate YAW is calculated as the unstable running state detection value. ΔYAW = | YAW-YAW |

In the following step S104, it is determined whether or not the differential yaw rate value ΔYAW exceeds the knockback control threshold value NBs, and if YES (ΔYAW> NBs), the process proceeds to step S105. Since the knockback control threshold NBS is for determining whether or not there is a high possibility of starting the vehicle behavior control, the vehicle behavior control is started when an oversteer state (unstable running state) occurs. Is set to a value smaller than the VDC intervention threshold VDCs. Steps S103 and S1
Reference numeral 04 constitutes the unstable traveling estimating means 23.

In a succeeding step S105, it is determined whether or not other wheels of the same system as the right front wheel are in the non-pressure increasing control state,
If YES (non-pressure increasing control state), step S10
After proceeding to step 6 to energize and close the other pressure increase control valve 5b of the same series, the procedure proceeds to step S107. By closing the other pressure increase control valve 5b of the same series, the communication state between the wheel cylinder WCFR for the right front wheel and the wheel cylinder WCRL for the left rear wheel is cut off on the side of the branch circuit 2b.

Incidentally, the determination in step S105 is NO.
When the other wheel of the same system as the front right wheel is in the pressure increasing control state, the control of step S106 is unnecessary, and thus the process directly proceeds to step S107. And this step S1
At 07, the normally open OUT side gate valve 3 is energized and closed to shut off the second channel circuit 2 itself. That is, at this point, only the pressure increase control valve 5a or both pressure increase control valves 5a and 5b are in a closed circuit state in which they are opened. Therefore, even if lateral acceleration acts on the vehicle in this state, the brake piston 33 of the wheel cylinder WCFR for the right front wheel moves to the right in FIG.
In FIG. 5, the movement to the right in the brake release direction) is completely prevented. The steps S106 and S107 constitute the backward movement prevention control means 24.

In a succeeding step S108, it is determined whether or not the differential yaw rate value ΔYAW exceeds the VDC intervention threshold value VDCs. When YES (ΔYAW> VDCs), the vehicle is in the oversteer state, and the VDC control is performed. It proceeds to step S109. That is, this step S
At 109, the inside gate valve 9 is energized to open the valve, and the suction circuit 4a is opened. At the same time, the motor M is energized to drive the hydraulic pump 4 so that the hydraulic pressure in the wheel cylinder WCFR of the right front wheel is increased. By increasing the pressure and thereby generating a braking force on the right front wheel, the oversteer state can be avoided. With the above, one flow is completed, and thereafter, the above flow is repeated.

That is, in the knockback control of the brake fluid pressure control apparatus according to the embodiment of the present invention, as shown in the time chart of FIG.
When it is determined that the possibility of an oversteer state (unstable running) has increased, and the other wheel (left rear wheel) side of the same system as the second channel circuit 2 is in the non-pressure increasing control state, the reverse blocking control means. In 24, the other wheel of the same system as the second channel circuit 2 that closes the out-side gate valve 3 and closes the out-side gate valve 3 prior to the start of the unstable-travel avoidance control by the unstable travel avoidance control means 22. The pressure increasing control valve 5b on the side is closed (steps S101 → S102 → S103 → S104 → S105 →
(S106 → S107 flow), whereby the hydraulic pressure escapes to the wheel cylinder WCRL side of the other wheel (left rear wheel) that is not pressure-intensifying controlled via the pressure increase control valve 5b on the other wheel side of the same system. As a result, it is possible to prevent the brake piston 33 of the wheel cylinder WCFR at the unstable traveling avoidance control start side wheel (right front wheel) by the unstable traveling avoidance control means 22 from retreating in the direction away from the rotor 31. Become.

That is, the other wheel (left rear wheel) side of the same system is in a non-pressurized control state, and the brake piston 33 is moving in the direction away from the rotor 31 due to lateral acceleration, and the rotor 31 Even when the rotor 31 and the brake piston 33 are separated from each other by the amount of eccentricity, the pressure increase control valve 5b on the other wheel (left rear wheel) side of the same system.
The hydraulic pressure can be prevented from escaping to the wheel cylinder WCRL side of the other wheel (the left rear wheel) by closing the wheel cylinder WCFR. It is possible to reliably prevent the brake piston 33 from moving backward in the direction away from the rotor 31.

After that, when the unstable running avoidance control means 22 detects oversteer (unstable running state) and VDC control is started, the in-side gate valve 9 is energized to open the intake circuit. 4a is opened and at the same time, the motor M is energized to drive the hydraulic pump 4 to increase the hydraulic pressure in the wheel cylinder WCFR of the right front wheel, thereby generating a braking force on the right front wheel and thereby oversteering. A condition can be avoided and VDC
Since the brake piston 33 is in contact with the rotor 31 at the start of the control, as shown by the solid line in FIG. 7, the hydraulic pressure of the wheel cylinder WCFR of the right front wheel is changed at the same time when the VDC control is started. Can be raised. Therefore, the deterioration of the brake pressure boosting characteristic is prevented and V
The effect that the control response of the DC control can be improved is obtained.

Although the embodiments of the present invention have been described with reference to the drawings, the present invention is not limited thereto. For example, in the embodiment of the invention, the vehicle having the X piping is described as an example, but the invention can be similarly applied to the vehicle having the H piping. Further, in the embodiment of the invention, the example in which only the hydraulic pump is provided has been described, but the present invention can be similarly applied to the case where the supercharging pump is added.

Further, in the embodiment of the invention, the oversteer state was described as an example of the unstable traveling state, but the present invention is also applied to the understeer state and other cases where the vehicle attitude is likely to be disturbed. be able to. Further, in the embodiment of the invention, the example in which the yaw rate sensor is used as the actual yaw rate calculating means 211 which is the unstable traveling state detecting means has been shown, but a lateral acceleration sensor provided in front of and behind the vehicle may be used. . Further, in the embodiment of the invention, the example in which the steering angle sensor is used as the target yaw rate calculation means 212 has been shown, but the target yaw rate calculation means 212 may be calculated based on the slip angle.

[0041]

As described above in detail, in the brake fluid pressure control device according to the first aspect of the present invention, the unstable traveling state is detected by detecting the unstable traveling state based on the lateral acceleration acting on the vehicle. The state detecting means, and when the unstable traveling state is detected by the unstable traveling state detecting means, the outer side gate valve of at least one wheel is closed so as to oppose the lateral acceleration generated in the vehicle. Unstable traveling avoidance control means for driving a hydraulic pump to supply pressurized hydraulic pressure to the wheel cylinder of the wheel, and unstable traveling based on the unstable traveling state detection value detected by the unstable traveling state detecting means. Unstable traveling estimating means for determining whether the possibility of unstable traveling has increased, and the unstable traveling avoiding control means when the unstable traveling estimating means determines that the possibility of unstable traveling has increased. By providing a means for preventing the brake piston of the wheel cylinder from retracting in the direction away from the rotor by closing the OUT side gate valve prior to the start of control, Since the brake piston is prevented from retracting in the direction away from the rotor due to the generated lateral acceleration, stroke loss of the brake piston does not occur when the brake pressure is increased in the subsequent unstable running avoidance control, and As a result, it is possible to prevent the deterioration of the brake pressure boosting characteristic and improve the control response.

In the brake fluid pressure control device according to claim 2, in the brake fluid pressure control device according to claim 1, H
A main circuit of two systems branched to two wheels on the left and right by pipes or X pipes is provided, the outside gate valve is provided in the main circuit of each system, and pressure increase control of each wheel is provided in each branch circuit. A valve is provided, the reverse movement prevention control means determines that the unstable traveling possibility is increased by the unstable traveling estimating means, and the other wheel side of the same system as the main circuit that closes the outside gate valve When the pressure increase control valve is controlled to open, the outside gate valve is closed prior to the control of the unstable running avoidance control means, and the other wheel of the same system as the main circuit that closes the outside gate valve is closed. By closing the pressure increase control valve on the side, the brake piston of the wheel cylinder is configured to prevent the brake piston from retracting in the direction away from the rotor. Even if the brake piston on the other wheel side is moving in the direction away from the rotor due to lateral acceleration, or if the rotor and brake piston are separated by the amount of eccentricity of the rotor, By closing the pressure increase control valve on the other wheel side of the system, it is possible to prevent the hydraulic pressure from escaping to the wheel cylinder side of the other wheel, which allows the brake pressure in the subsequent unstable traveling avoidance control. The occurrence of stroke loss of the brake piston at the time of increasing the pressure is eliminated, so that the deterioration of the brake pressure boosting characteristic can be prevented and the control response can be improved.

[Brief description of drawings]

FIG. 1 is an overall view showing a pressure increase control state of a brake fluid pressure control device according to an embodiment of the invention.

FIG. 2 is an overall view showing a holding control state of a brake fluid pressure control device according to an embodiment of the invention.

FIG. 3 is an overall view showing a pressure reduction control state of a brake fluid pressure control device according to an embodiment of the invention.

FIG. 4 is a block diagram showing the content of knockback control in the brake fluid pressure control device according to the embodiment of the invention.

FIG. 5 is an explanatory diagram showing a wheel cylinder portion in the brake fluid pressure control device according to the embodiment of the present invention.

FIG. 6 is a flowchart showing the content of knockback control in the brake fluid pressure control device according to the embodiment of the invention.

FIG. 7 is a time chart showing the contents of knockback control in the brake fluid pressure control device according to the embodiment of the invention.

[Explanation of symbols]

WSFR front right wheel cylinder WSRL Left rear wheel cylinder BP brake pedal MC master cylinder RT reservoir tank 1st channel circuit (main circuit) 2 Second channel circuit (main circuit) 2a branch circuit 2b branch circuit 2c Gate valve bypass circuit 2d one-way valve 2e branch point 2f bypass circuit 2g one-way valve 2h connection point 3 Out side gate valve 4 hydraulic pump 4a Inhalation circuit 4b discharge circuit 4c one-way valve 5a Boost control valve 5b Boost control valve 6a Pressure reducing control valve 6b Pressure reducing control valve 7 Reservoir 8 Discharge circuit (drain circuit) 9 Inside gate valve 31 rotor 32a brake pad 32b brake pad 33 Brake piston

Claims (2)

[Claims] 1. A master cylinder that generates hydraulic pressure in response to a driver's brake operation, and a brake pad that is arranged so as to face a rotor that rotates integrally with a wheel in the axial direction of the rotational axis of the wheel by introducing hydraulic pressure. A wheel cylinder that generates a braking force by pressing with an operating brake piston; a main circuit that connects the wheel cylinder and the master cylinder; a normally open pressure increasing control valve that opens and closes the main circuit; A normally open outside gate valve that opens and closes a main circuit between the pressure control valve and the master cylinder, and a normally closed pressure reducing control valve that opens and closes a drain circuit that discharges the hydraulic pressure of the wheel cylinder to a reservoir. The discharge circuit is connected to the main circuit between the outside gate valve and the pressure increase control valve, while the suction circuit is connected to the master cylinder and the reservoir. Hydraulic pump for supplying pressurized hydraulic pressure to the main circuit side, a normally open in-side gate valve that opens and closes the suction circuit, operation of the pressure increasing control valve, pressure reducing control valve and both gate valves, and liquid A brake fluid pressure control device comprising: a brake fluid pressure control means for controlling driving of a pressure pump; and an unstable traveling state detection means for detecting an unstable traveling state based on a lateral acceleration acting on a vehicle, When an unstable traveling state is detected by the stable traveling state detecting means, the out-side gate valve of at least one wheel is closed and the hydraulic pump is driven so as to oppose the lateral acceleration generated in the vehicle. The unstable traveling avoidance control means for supplying a pressurized hydraulic pressure to the wheel cylinder of the wheel, and the possibility of unstable traveling based on the unstable traveling state detection value detected by the unstable traveling state detecting means. Unstable driving estimating means for determining whether or not the vehicle has become unstable, and when the unstable traveling estimating means determines that the possibility of unstable traveling has increased, the unstable driving avoiding control means starts the control on the outside side. A brake fluid pressure control device, comprising: a retraction prevention control unit that prevents the brake piston of the wheel cylinder from retreating in a direction away from the rotor by closing the gate valve. 2. A main circuit of two systems branched to two wheels on the left and right by H piping or X piping is provided, and the main gate of each system is provided with the outside gate valve and each branch circuit is provided. A pressure increase control valve for each wheel is provided, and the reverse movement prevention control unit is the same as the main circuit that determines that the unstable traveling possibility is increased by the unstable traveling estimation unit and closes the outside gate valve. When the other wheel side of the system is in the non-pressure increasing control state, the outside gate valve is closed prior to the start of the control of the unstable traveling avoidance control means, and the other of the same system as the main circuit that closes the outside gate valve Is configured so as to prevent the brake piston of the wheel cylinder from retracting in the direction away from the rotor by closing the pressure increase control valve on the wheel side. Brake fluid pressure control apparatus according to claim 1.