JPH11348755A - Brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure a sufficient amount of fluid for intensifying pressure of a wheel cylinder at automatic braking control and to secure controllability and stableness of a vehicle even for the constitution that the length of a relief part surrounded by a main pump, a fluid pressure control valve, gate valve on the out side and a relief valve is made short to secure compactness and control responsiveness in a brake device which can execute automatic barking control. SOLUTION: In a brake device having a brake circuit c for connecting a master cylinder 'a' to a wheel cylinder 'b' provided with a drain circuit 'd' a reservoir 'e', a fluid pressure control valve 'f', a circulation circuit 'g', a gate valve on the out side 'm' and a gate valve on the in side 'k', constituted so that a barking force can be generated automatically, a fluid reservoir 'q' for accumulating a predetermined amount of a brake fluid is provided at a relief part constituted by a part of the brake circuit 'c' surrounded by the gate valve 'm' on the out side, the relief valve 'n', the fluid pressure control valve 'f' and the main pump 'h' and a part of the circulation circuit 'g'.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake device capable of executing an automatic braking control for generating a braking force as required irrespective of the presence or absence of a driver's braking operation.

[0002]

2. Description of the Related Art Conventionally, there has been known a brake device capable of executing an automatic braking control for automatically generating a braking force even when a driver is not performing a braking operation as required. Here, the automatic braking control is, specifically, when the vehicle is in an over-steer or over-understeer state,
A yaw moment control for generating a braking force on an arbitrary wheel so as to generate a yaw moment in a neutral direction with respect to the vehicle, or a wheel on which a drive wheel slip occurs to suppress the drive wheel slip when the drive wheel slips Or brake assist control for applying a braking force when it is determined that the braking force is insufficient when the driver is performing a braking operation.

A brake device capable of performing the above-described automatic braking control includes a hydraulic pressure control valve provided in the middle of a brake circuit connecting the master cylinder and the wheel cylinder, for supplying and discharging brake fluid to and from the wheel cylinder. A reservoir for storing the brake fluid discharged from the wheel cylinder at the time of pressure reduction, a main pump for returning the brake fluid of the reservoir to the brake circuit, a feeding circuit connecting the main pump to the master cylinder side, and an in-side for opening and closing the feeding circuit A gate valve, an out-side gate valve provided on the master cylinder side of the discharge position of the main pump to open and close the brake circuit, and a brake circuit provided in parallel with the out-side gate valve and having a predetermined pressure on the wheel cylinder side. When the pressure is exceeded, a relief valve that allows the brake fluid on the wheel cylinder side to escape to the master cylinder side, Those with is common. That is, in the brake device having this structure, when it is necessary to generate a braking force in a state where the driver is not performing the braking operation and the master cylinder pressure is not generated, the out-side gate valve is closed. While shutting off the master cylinder and the wheel cylinder, the in-side gate valve is opened and the suction side of the main pump communicates with the master cylinder. When the main pump is driven in this state, the master cylinder side The brake fluid is discharged toward the brake circuit, and the operation of the hydraulic pressure control valve is controlled so that a desired amount of brake fluid is supplied and discharged to a desired wheel cylinder, so that a desired control is performed on a desired wheel. Power can be generated.

[0004] Incidentally, in the charging circuit, a configuration in which a charging pump is provided in series with the main pump, or a piston that strokes by the discharge pressure of the charging pump is provided so that the brake fluid is supplied by the stroke of the piston. A configuration for supplying the brake fluid to the main pump is provided as in the configuration described above (for example, see Japanese Patent Application Laid-Open No. 7-501506), and the brake fluid is instantaneously supplied to the main pump during the automatic braking control. There is known one that ensures a boost response in braking control.

[0005] The brake circuit connecting the master cylinder and the wheel cylinder is finally branched into four systems toward each wheel cylinder, but the part for discharging the main pump is divided into four parts. Is generally configured to discharge to the respective systems of the part branched into two systems. Therefore, an in-side gate valve, an out-side gate valve, a relief valve, and the like are provided in each of these two systems, and a main pump and a supply pump are also provided so as to discharge brake fluid toward each of the systems. It is configured.

[0006]

By the way, in the brake circuit, which is the target part of the hydraulic pressure relief by the relief valve, between the outside gate valve and the relief valve and the hydraulic pressure control valve, and in the recirculation circuit, the main pump Since the discharge side may be subject to high pressure, which is the sum of the pump discharge pressure and the master cylinder pressure, the hydraulic rigidity is set high to withstand this high pressure. Considering this, it is disadvantageous to make these paths long, so that the oil path of the relief target portion is formed short. For this reason, the volume that can store the brake fluid in the relief target portion is configured to be small.

However, according to the above-mentioned prior art, when increasing the pressure of at least two wheel cylinders connected to the same brake circuit during automatic braking control,
The brake fluid discharged from the main pump to the brake circuit is supplied to the two wheel cylinders. As described above, since the hydraulic rigidity of the relief target portion is high and the volume is small, it is necessary to raise the pressure of all wheel cylinders. In some cases, the required amount of brake fluid may not be obtained, and there is a possibility that the problem of poor boost response may occur. Further, when increasing the pressure of at least two wheel cylinders, when the pressure of one of the wheel cylinders is controlled at a high pressure and the other wheel cylinder is controlled at a low pressure, the pressure of the low-pressure wheel cylinder is increased. Due to the high hydraulic rigidity and small volume of the target part, when the brake fluid is insufficient to increase the pressure as described above, the brake fluid of the wheel cylinder, which is controlled to a high pressure, flows in parallel with the hydraulic pressure control valve. In some cases, the check valve provided may be opened, flow out, and flow into the low-pressure wheel cylinder. In this case, the wheel cylinder pressure that has been controlled to a high pressure differs from the control hydraulic pressure. As a result, the controllability of the vehicle is deteriorated and the stability of the vehicle is deteriorated. In the relief target portion surrounded by the main pump, the hydraulic pressure control valve, the out-side gate valve, and the relief valve, the discharge side of the main pump is
A configuration in which a damper for absorbing pulsation and an orifice are provided in series has also been considered. Therefore, it is conceivable to secure a sufficient amount of liquid in the above-described path with this damper.
However, even if the amount of fluid is secured by this damper, the brake fluid in the damper is not supplied to the wheel cylinder unless it passes through the orifice, so the supply speed of the brake fluid to the wheel cylinder is delayed. As described above, the brake fluid flows from the high-pressure wheel cylinder to the low-pressure wheel cylinder,
This leads to deterioration of stability. In particular, as the main pump, a plunger-type pump that repeats a suction stroke and a discharge stroke due to a reciprocating stroke of a plunger accompanying rotation of a motor may be used, but such a plunger-type pump is used. When used, the brake fluid is supplied to the relief target portion only when the main pump is performing the discharge stroke. Therefore, when the pressure of the low-pressure wheel cylinder is increased as described above, if the main pump is performing the suction stroke, only the volume of the brake fluid existing in the relief target portion can be supplied. The outflow of brake fluid from the high pressure side wheel cylinder as described above is likely to occur.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems. In a brake device capable of executing automatic braking control, a main pump and a hydraulic pressure control are required to ensure miniaturization and control responsiveness. Even if the length of the relief target section surrounded by the valve / outside gate valve and relief valve is shortened, ensure a sufficient amount of fluid to increase the pressure of the wheel cylinder during automatic braking control. It is intended to ensure the controllability and stability of the vehicle.

[0009]

According to a first aspect of the present invention, there is provided a brake circuit in which a master cylinder a and a plurality of wheel cylinders b are connected as shown in FIG. In the middle of c, wheel cylinder b
Is connected to the master cylinder a side, the wheel cylinder b is connected to the reservoir e via the drain circuit d, and the wheel cylinder b is connected to the master cylinder a and the reservoir e.
A fluid pressure control valve f is provided to control the fluid pressure of each wheel cylinder b in a state in which the fluid pressure control valve f is disconnected from the reservoir e and the master cylinder a side with respect to the fluid pressure control valve f of the brake circuit c. A main pump h that discharges the brake fluid of the reservoir e to the brake circuit c is provided in the middle of the connected recirculation circuit g, and a supply circuit j that can supply the brake fluid to the suction side of the main pump h is connected to the main pump h. An in-side gate valve k for opening / closing the supply circuit j is provided, and an out-side gate valve m for opening / closing the brake circuit c is provided between the discharge position of the main pump h in the brake circuit c and the master cylinder a. Also, in parallel with the out-side gate valve m, when the fluid pressure downstream of the out-side gate valve m exceeds a predetermined pressure, the valve is opened to release the brake fluid from the out-side gate valve m. A relief valve n is provided for releasing the brake fluid of the wheel cylinder b to the master cylinder a in parallel with the hydraulic pressure control valve f and the out-side gate valve m. Irrespective of whether the driver is performing the braking operation or not, the main pump h causes the supply circuit j to discharge the brake fluid to the brake circuit c, and the brake fluid is further released by the hydraulic pressure control valve f to the wheel cylinder. b, a brake device configured to be able to automatically generate a braking force by supplying a desired amount to the main pump h, a brake surrounded by the main pump h, an out-side gate valve k, a relief valve n, and a hydraulic control valve f. A fluid reservoir q for accumulating a predetermined amount of brake fluid is provided in a relief target portion formed by a part of the circuit c and a part of the reflux circuit g. According to a second aspect of the present invention, in the brake device according to the first aspect, the main pump h is of a plunger type in which a plunger performs a reciprocating stroke with a rotation of a motor to suck and discharge brake fluid. The volume q3 required for increasing the pressure of the wheel cylinder b from the low pressure state per time required for the motor to make one rotation is as follows:
It is preferable to set the amount to be equal to or less than the amount (q1-q2) obtained by subtracting the consumed amount q2 of the wheel cylinder at the time of the wheel lock hydraulic pressure from the consumed amount q1 of the wheel cylinder b at the time of the relief pressure. Alternatively, as in the invention according to a third aspect, in the brake device according to the first aspect, the main pump h
A plunger model in which the plunger makes a reciprocating stroke with the rotation of the motor to suck and discharge brake fluid is used, and the volume of the liquid reservoir q is reduced by the pump discharge amount q4 per motor rotation. It is preferable that the amount is set to be equal to or less than (q1−q2) obtained by subtracting the wheel cylinder consumption liquid amount q2 at the time of wheel lock hydraulic pressure from the wheel cylinder consumption liquid amount q1 at the time of compression. Claim 4
The brake device according to any one of claims 1 to 3, wherein the discharge side of the main pump h of the recirculation circuit g is provided with a damper and an orifice for absorbing a pulse pressure in order from the main pump h side. The liquid reservoir q is returned to the reflux circuit g
Is preferably provided on the brake circuit side with respect to the orifice. Further, as in the invention according to claim 5, in the brake device according to any one of claims 1 to 4, it is preferable that the supply circuit j is provided with a supply means r for sending brake fluid toward the suction side of the main pump h. . Specifically, as the charging means r, a charging pump provided in a charging circuit j connected to the master cylinder a for discharging the brake fluid on the master cylinder a side to the main pump h, as described in claim 6 Or claim 7
As described above, the supply means includes a supply piston provided with a piston defined in a cylinder as a supply chamber and a pressure chamber so as to be slidable, and a pressure chamber for sucking brake fluid on the master cylinder a side. And a feeding pump for discharging to a pressure circuit connected to the feeding circuit, and the feeding chamber is connected to the feeding circuit j.

(Function) In the present invention, during automatic braking control, the in-side gate valve k is opened to open the charging circuit j, and the out-side gate valve m is closed to open the brake circuit c.
The main pump h is driven so that the brake fluid can be supplied to the suction side of the main pump h, and the supplied brake fluid is discharged toward the brake circuit c.
The brake circuit c is discharged to a relief target portion surrounded by the out-side gate valve m, the relief valve n, the hydraulic pressure control valve f, and the main pump h, and the hydraulic pressure control valve f brakes the relief target portion. The fluid is supplied to the wheel cylinder b or the brake fluid of the wheel cylinder b is discharged to the reservoir e to control the pressure of the wheel cylinder b to generate a desired braking force on a desired wheel. By the way, in the relief target portion constituted by a part of the brake circuit c from which the brake is discharged from the main pump h and a part of the recirculation circuit g, when the pressure exceeds a predetermined pressure, the relief valve n is opened and the brake fluid is discharged. The relief valve n is released upstream of the out-side gate valve m, and does not exceed the set valve opening pressure of the relief valve n. During the automatic braking control, when the brake fluid is discharged from the main pump h to the relief target portion, the brake fluid is accumulated in the fluid reservoir q provided in the relief target portion, and the pulse pressure of the main pump h is reduced. It is absorbed by the liquid reservoir q.

Therefore, the amount of brake fluid that can be supplied from the relief target portion when the pressure of the wheel cylinder a is increased can be increased by the volume of the liquid reservoir q without increasing the length of the relief target portion, and the boosting performance can be increased. Can be improved. Therefore, in a structure in which the brake fluid is supplied from one main pump h to a plurality of wheel cylinders b, there are some of the plurality of wheel cylinders b that are controlled to a high pressure and those that are controlled to a low pressure. Therefore, when increasing the pressure of the wheel cylinder b controlled to a low pressure, if the volume of the liquid reservoir q is secured, the pressure of the low-pressure wheel cylinder b can be sufficiently increased, and the pressure of the high-pressure It is possible to prevent the brake fluid in the wheel cylinder b from flowing out to the low-pressure wheel cylinder b by opening the check valve p. Therefore, the pressure of the wheel cylinder b does not change from the control pressure, and the controllability of the vehicle is improved.
Stability is improved.

In particular, when a plunger type pump is used as the main pump h as in the second or third aspect of the present invention, the brake fluid is supplied to the relief target portion only when the main pump h is in the discharge stroke. Is not performed, and the brake fluid is not supplied to the relief target portion during the suction stroke. Therefore, when the pressure of the wheel cylinder b is increased in the suction stroke of the main pump h, only the brake fluid stored in the relief target portion can be supplied. However, in the invention described in claim 2,
The volume q3 required to increase the pressure of the low-pressure wheel cylinder b per time required for the motor to make one rotation is determined by the amount q1 of the consumed liquid q1 of the wheel cylinder b at the time of the relief pressure. Wheel cylinder liquid consumption q at hydraulic pressure
2 is set so as to be equal to or less than (q1−q2). Therefore, when increasing the pressure of the low-pressure wheel cylinder b as described above, it is assumed that the pressure of the wheel cylinder b is increased from the atmospheric pressure to the maximum lock hydraulic pressure. Also, before the main pump h performs the next discharge, the brake fluid required for supply can be covered by the brake fluid accumulated in the fluid reservoir, and the high-pressure wheel cylinder b is supplied with the low-pressure wheel cylinder b as described above. It does not flow out to the wheel cylinder b. Similarly, the invention according to claim 3 provides a pump discharge amount q per one rotation of the motor.
4 is the consumed liquid amount q1 of the wheel cylinder b at the time of the relief pressure.
Is set to be equal to or less than the amount (q1-q2) obtained by subtracting the wheel cylinder consumption liquid amount q2 at the time of the wheel lock hydraulic pressure from (1), the same operation is obtained.

According to the invention described in claim 4, the main pump h
Is absorbed by the damper and the orifice, the brake fluid is supplied to the relief target portion, and is also accumulated in the fluid reservoir q. Therefore, when increasing the pressure of the wheel cylinder b, the brake fluid stored in the fluid reservoir q is supplied to the wheel cylinder b without being throttled by the pulse pressure absorbing orifice. According to the fifth aspect of the present invention, at the time of automatic braking control, the supply means r is operated to supply the brake fluid to the main pump h via the supply circuit j. Therefore, the brake fluid is smoothly supplied to the main pump h, and the main pump h can be configured to have a small size and a small capacity, so that the device can be downsized and the control response can be ensured. According to the sixth aspect of the present invention, at the time of the automatic braking control, the feeding pump is connected to the feeding circuit j.
To supply the brake fluid on the master cylinder a side to the suction side of the main pump h. In the seventh aspect of the present invention, at the time of automatic braking control, the supply pump supplies the brake fluid on the master cylinder a side to the pressure chamber of the supply piston through the pressure circuit, whereby the piston of the supply piston strokes, and the supply chamber is supplied. Is supplied to the suction side of the main pump h via the feeding circuit by an amount corresponding to this stroke.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) First, the overall structure of a brake device according to Embodiment 1 will be described with reference to FIG. In the figure, W
C (FL) is a wheel cylinder for the left front wheel, WC (RR) is a wheel cylinder for the right rear wheel, WC (FR) is a wheel cylinder for the right front wheel, WC (RL) is a wheel cylinder for the left rear wheel,
MC is a master cylinder. The master cylinder MC
Each of the wheel cylinders WC (FL) to W via the brake circuits 1 and 2 in conjunction with the depression of the brake pedal BP.
The brake fluid is supplied to C (RL), and a reservoir tank RT for storing the brake fluid is provided. The brake circuits 1 and 2 include wheel cylinders WC (FL) and WC on the left front wheel and the right rear wheel.
(RR) and the wheel cylinders WC (FR) and WC (RL) on the right front wheel and the left rear wheel.
, And a brake circuit 2 connected to the X-ray tube is piped in an X-shape. When the wheel cylinders WC (FL) to WC (RL) do not indicate a specific one, they are simply described as WC.

A brake unit BU is provided in the middle of the brake circuits 1 and 2. The brake unit BU is configured to be able to reduce, maintain, and increase the hydraulic pressure of the wheel cylinder WC, and is disposed, for example, in an engine room (not shown). Hereinafter, the configuration of the brake unit BU will be described in detail. However, since the configurations provided for both the brake circuits 1 and 2 are the same, only the configuration relating to the brake circuit 1 will be described below. The same reference numerals are given to the same components as those described above, and the description of the configuration relating to the brake circuit 2 will be omitted.

In the brake unit BU, the brake circuit 1 includes a rear wheel branch circuit 1r which reaches a wheel cylinder WC (RR) of a right rear wheel at a branch point 1d, and a wheel cylinder WC (FL) of a left front wheel. Front wheel branch circuit 1
and f. Also, upstream of the branch point 1d,
An out-side gate valve 3 is provided, and a gate valve bypass circuit 1b and a relief circuit 1m that bypass the out-side gate valve 3 are provided. The out-side gate valve 3 is constituted by a normally open two-port two-position electromagnetic switching valve that connects the brake circuit 1 with a spring force when not in operation and shuts off the brake circuit 1 when in operation. . In addition, the gate valve bypass circuit 1
b is from the master cylinder MC side to the wheel cylinder WC side (hereinafter, the side relatively closer to the master cylinder MC is referred to as upstream, and the side closer to the wheel cylinder WC is referred to as downstream) by the one-way valve 1c provided in the middle. Is configured to allow only distribution. In the middle of the relief circuit 1m, there is provided a relief valve 20 for releasing the hydraulic pressure upstream when the downstream hydraulic pressure becomes equal to or higher than a predetermined pressure.

Each of the branch circuits 1r and 1f is provided with an inflow valve 5 and an outflow valve 6 which constitute a hydraulic pressure control valve for reducing, holding and increasing the brake fluid pressure of each wheel cylinder WC. That is, when the inflow valve 5 is not operated, the branch circuits 1r and 1f are in communication with each other by a spring force to connect the wheel cylinder WC to the master cylinder MC side. It is constituted by a normally open 2-port 2-position electromagnetic switching valve that shuts off the WC from the master cylinder MC side. The outflow valve 6 is connected to each of the branch circuits 1r, 1r.
f, which is provided in the middle of a drain circuit 10 branched from branch points 1e, 1e provided downstream of the inflow valve 5 (wheel cylinder WC side) and reaching the reservoir 7, and shuts off the drain circuit 10 when it is not operated. Wheel cylinder WC in reservoir 7
And a normally closed 2-port 2-position electromagnetic switching valve that connects the drain cylinder 10 and the wheel cylinder WC to the reservoir 7 during operation. Each branch circuit 1r, 1f is provided with an inflow valve bypass passage 1h having a valve 1g while bypassing the inflow valve 5 and allowing only the flow from downstream to upstream on the way. When the pressure upstream of wheel cylinder WC becomes lower than wheel cylinder WC, brake fluid is returned from wheel cylinder WC to master cylinder MC side.

The drain circuit 10 includes a drain circuit 10
Circuit 4 connecting the brake circuit 1 and a branch point 1d of the brake circuit 1
a is connected. The return circuit 4a is provided with a main pump 4 for discharging the brake fluid of the reservoir 7 to a branch point 1d of the brake circuit 1. The main pump 4 is of a plunger type in which the volume of the compression chamber 4e changes with the reciprocating stroke of the plunger 4p in the axial direction to perform suction and discharge. In the middle of the recirculation circuit 4a, the reservoir 7 at the time of inhalation is used.
A suction valve 4h that allows backflow to the reservoir 7 during discharge while permitting suction from the suction side, and a discharge valve 4 that allows backflow to the branch point 1d during discharge and prevents backflow from the branch 1d during suction.
b. A branch point 4j provided at a position closer to the main pump 4 than the suction valve 4h in the middle of a recirculation circuit 4a connecting the drain circuit 10 and the branch point 1d has a suction side of the main pump 4. A feeding circuit 8a for connecting the master cylinder MC is provided. In the middle of the supply circuit 8a, a supply pump 8 for performing a supply operation for supplying the brake fluid of the master cylinder MC to the main pump 4 is provided. As in the case of the main pump 4, the charging pump 8 also has a compression chamber 8 as the plunger 8p reciprocates in the axial direction.
A plunger type in which the volume of e changes to perform suction and discharge is used. In the middle of the feeding circuit 8a, a suction valve 8c that allows suction from the master cylinder MC side during suction while preventing backflow to the master cylinder MC side during discharge, and discharges to the branch point 4j side during discharge. Discharge valve 8b that prevents backflow from branch point 4j during suction while allowing
Are provided. The boosting pump 8 is driven in series with the main pump 4 during automatic braking control to supply brake fluid from the master cylinder MC side to the suction side of the main pump 4 to improve the rise of the discharge pressure of the main pump 4. Although the upstream side of the supply circuit 8a is connected to the brake circuit 1, it may be connected directly to the master cylinder MC or the reservoir tank RT.

The plungers 4p and 8p of the main pump 4 and the feed pump 8 are configured to make a stroke in accordance with the rotation of the camshaft 11 rotated by one motor M. That is, when one motor M is driven, both pumps 4 and 8 can be driven simultaneously.

An in-side gate valve 9 is provided at a position upstream of the feed pump 8 in the feed circuit 8a. The in-side gate valve 9 shuts off the feeding circuit 8a by a spring force when not in operation, and the feeding circuit 8a when in operation.
And a normally closed 2-port 2-position electromagnetic switching valve.

In the brake circuit 1, a liquid reservoir 12 is provided at a position between a branch point 1 d, which is a discharge position of the brake fluid of the main pump 4, and the out side gate valve 3 and the relief valve 20. The reservoir 12 is formed by enlarging the diameter of a part of an oil passage constituting the brake circuit 1. The volume Q of the reservoir 12 is based on the pressure P-consumed liquid q characteristic shown in FIG. It is configured. In FIG. 3, P1 is the relief pressure of the relief valve 20, and P2 is the wheel lock hydraulic pressure. Note that the wheel lock hydraulic pressure is a standard wheel cylinder pressure when the wheel locks on a standard high friction coefficient (hereinafter, referred to as high μ) road surface,
It is determined by experiments. Further, q1 is the accumulated liquid amount of the liquid reservoir 12 at the time of the relief pressure, and q2 is the accumulated liquid amount of the liquid reservoir 12 at the time of the wheel lock hydraulic pressure. That is, the wheel cylinder WC (F) connected to the brake circuit 1
When one of L) and WC (RR) is controlled to a high pressure, the maximum value is the lock hydraulic pressure P2. Then, in order to increase the pressure of the other low-pressure wheel cylinder WC without lowering the pressure, the brake fluid amount Q3 used for the pressure increase may be set to (q1-q2) or less. Therefore, Q3 ≦ (q1-q2).
Note that the brake fluid amount Q3 is a brake fluid amount necessary for increasing the pressure of the wheel cylinder WC per time required for the motor M to make one rotation. Alternatively, the reservoir 1
The brake fluid 2 is periodically replenished from the main pump 4. Therefore, the liquid reservoir 12 is configured to accumulate a liquid amount necessary for increasing the pressure until the brake fluid is replenished by the main pump 4. In this case, (q1−q2) ≧ Q4 is set, and this Q4 is the amount of brake fluid discharged by the main pump 4 per one rotation of the motor M, and specifically, 0.1 to 0. The range is 2 cc. As shown in FIG. 4, the operations of the valves 3, 5, 6, 9 and the motor M of the above-mentioned electromagnetic valve structure are controlled by the control unit CU. That is, the control unit CU includes:
A wheel speed sensor S for detecting the rotation speed of the wheels, a yaw rate sensor YR for detecting the yaw rate of the vehicle body, a steering angle sensor H for detecting the steering angle of the vehicle, and a brake sensor BS for detecting whether or not a braking operation is being performed. , A sensor group SG having a G sensor GS for detecting the longitudinal and lateral acceleration of the vehicle is connected, and the control unit CU obtains a slip rate of each wheel based on signals input from these sensor groups SG. When the slip ratio exceeds a predetermined value during braking, ABS control is performed to keep the slip ratio within a predetermined range, and a braking force is generated as necessary according to the vehicle behavior regardless of whether or not the driver has performed a braking operation. The automatic braking control is performed. The automatic braking control includes a torque slip prevention control that suppresses a driving wheel slip when it occurs, and a braking force that is applied to a desired wheel when the vehicle is in an oversteer state or an understeer state. A yaw rate control that generates a yaw rate in a direction to stabilize the vehicle by performing a braking operation, and a brake assist control that generates a braking force to assist the braking force when it is determined that the braking force is insufficient when the driver performs the braking operation. Although at least one of these controls is not a feature of the present application, the details of these controls are omitted.

Here, the ABS control and the automatic braking control will be briefly described with reference to the flowcharts of FIGS. The ABS control is performed in step 10 as shown in FIG.
In step 1, the slip ratio of each wheel is determined based on the input from the wheel side sensor S, and in step 102, it is determined whether or not to execute the ABS control based on the slip ratio. If it is determined that the ABS control is to be performed,
In step 103, the opening and closing of the inflow valve 5 and the outflow valve 6 are controlled so that the motor M is energized and driven, and the above-described pressure reduction, holding, and pressure increase are performed to keep the slip ratio within the reference range. Then, in step 104, AB
It is determined whether the S control has been completed. If it is determined that the control has been completed, the process proceeds to step 105, where the inflow valve 5 is opened and the outflow valve 6 is closed. Stop energization.

In the automatic braking control, as shown in the flowchart of FIG. 6, if the vehicle state is determined in step 201, and if the automatic braking control is determined to be necessary in step 202 based on the vehicle state, step 20 is executed.
Proceeding to 3, the motor M, the out-side gate valve 3, and the in-side gate valve 9 are energized. Accordingly, the motor M is driven, the out-side gate valve 3 is closed, and the in-side gate valve 9 is closed.
Is opened. Then, in step 104, the opening and closing of the inflow valve 5 and the outflow valve 6 are controlled in accordance with the vehicle state,
When it is determined that the automatic braking control in step 105 has been completed, the motor M, the out-side gate valve 3, the in-side gate valve 9
Is cut off, and the process returns to step 101 for determining the vehicle state.

Next, the operation of the brake device according to the first embodiment will be described. a) Normal brake operation Normally, each of the valves 3, 5, 6, and 9 is in a non-operating state as shown in FIG. 2, that is, the out-side gate valve 3 is opened and the inflow is performed. The valve 5 is open and the outflow valve 6 is closed. When the brake pedal BP is depressed in this state, the brake fluid of the master cylinder MC passes through the brake circuits 1 and 2 through the branch circuits 1f and 1r via the out-side gate valve 3 and the inflow valve 5 to the wheel cylinders WC. The braking force is supplied, and a braking force corresponding to the depression force of the brake pedal BP is generated.

B) At the time of ABS control At the time of the above-described brake operation, when the wheels are locked or are likely to be locked, the control unit CU sets the wheel slip rate within a predetermined range and locks the wheels. ABS control is performed to prevent the above. This AB
In the S control, the inflow valve 5 of the branch circuits 1r and 1f connected to the wheel cylinder WC for braking the wheel which is likely to be locked is closed, and the outflow valve 6 is opened. As a result of the closing of the inflow valve 5, the pressure in the wheel cylinder WC is not increased, and the brake fluid in the wheel cylinder WC is discharged to the reservoir 7 through the drain circuit 10 to be reduced in pressure, thereby weakening the braking force. The brake fluid stored in the reservoir 7 is returned to the brake circuit 1 at any time by the drive of the main pump 4 via the return circuit 4a.

If the wheel slip ratio falls below a predetermined value as a result of the reduction of the braking force, the control unit CU stops supplying power to the outflow valve 6 and closes the outflow valve 6 to control the outflow valve 6. The hydraulic pressure of the target wheel cylinder WC is maintained, and when the slip ratio is reduced to a value less than another predetermined value as a result of the holding operation, the power supply to the inflow valve 5 is cut off to open the valve. The high-pressure brake fluid of the brake circuit 1 is supplied to the wheel cylinder WC, and the braking force increases again. By repeating the above operations, the maximum braking force can be obtained while keeping the slip ratio of each wheel within a predetermined range while the brake pedal BP is being depressed, while preventing the wheels from being locked.

During the above ABS control, the main pump 4
, The plunger 8p performs a stroke as the camshaft 11 rotates by driving the motor M even in the feed pump 8. However, at this time, the in-side gate valve 9 maintains the closed state. Therefore, when the plunger 8p of the charging pump 8 performs the suction stroke, the brake fluid cannot be sucked from the master cylinder MC side, and therefore, the charging pump 8 does not perform the charging operation.

C) At the time of automatic braking control When executing automatic braking control including torque slip prevention control, yaw rate control, and brake assist control, the control unit CU drives the motor M based on the control shown in FIG. And a brake circuit 1 to which a wheel cylinder WC to be controlled is connected.
2 to the outer side gate valve 3 to supply the brake circuits 1 and 2
Is shut off, and both the in-side gate valves 9 of the supply circuits 8a, 8a for supplying the brake circuits 1, 2 to be controlled are energized to communicate the supply circuit 8a. In this case, for example, in FIG. 2, the wheel cylinder WC (F
When the braking force is generated only in L), only the gate valves 3 and 9 on the brake circuit 1 side are switched, and the gate valves 3 and 9 provided on the brake circuit 2 side are not energized. Keep in state.

Therefore, in the charging circuit 8a in which the in-side gate valve 9 is open, the charging pump 8 is driven, and the brake fluid of the master cylinder MC is supplied to the suction side of the main pump 4, and this brake fluid is It is supplied to the brake circuits 1 and 2 by the pump 4 via the return circuit 4a.
Therefore, even when the master cylinder pressure is not generated or the master cylinder pressure is insufficient, the inflow valve 5 and the outflow valve 6 are opened and closed to supply an arbitrary amount of the brake fluid to an arbitrary wheel cylinder WC. It can be supplied to generate a desired braking force on a desired wheel.

At the time of this automatic braking control, in this embodiment, the brake fluid discharged from the main pump 4 is stored in the reservoir 1.
2 is stored. Therefore, for example, the brake circuit 1
, One wheel cylinder WC (FL) is controlled to a high pressure and the other wheel cylinder WC (RR) is controlled to a low pressure, and then the other wheel cylinder WC (RR) is controlled to a low pressure.
When (RR) is controlled to a high pressure, even if the main pump 4 is performing the suction stroke at this time,
The brake fluid accumulated in the fluid reservoir 12 is stored in the wheel cylinder WC.
(RR). And the volume Q of this liquid reservoir 12
Is set under the above-described conditions, the brake fluid flows out of the wheel cylinder WC (FL), which has one high pressure (the maximum lock fluid pressure P2), and the wheel cylinder WC (RR) on the low pressure side Does not interfere with Therefore, the wheel cylinder pressure does not differ from the pressure to be controlled by the control unit CU, and the controllability and stability of the vehicle back can be improved. In addition, the liquid reservoir 12 absorbs the pulse pressure of the plunger-type main pump 4, thereby improving the sound and vibration performance. The liquid reservoir 12 is formed by enlarging a part of the path surrounded by the main pump 4, the out-side gate valve 3, and the relief valve 20, without increasing the length of the path. The size of the brake unit BU can be minimized to improve the in-vehicle performance, and the responsiveness does not decrease due to an increase in the flow path resistance.

Hereinafter, other embodiments will be described. In describing these embodiments, the same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and description thereof will be omitted. Only the differences from the first embodiment will be described. Only the differences between the first embodiment and the first embodiment will be described.

(Embodiment 2) FIG. 7 is an overall view of a brake device according to Embodiment 2 of the present invention. In Embodiment 2, a recirculation circuit 4a suppresses a pulse pressure upstream of a discharge valve 4b of a main pump 4. In this example, a damper 4c and an orifice 4d are provided. In the case of such a configuration, the liquid reservoir 12 is provided upstream (the brake circuits 1 and 2) of the orifice 4d.

As described above, since the liquid reservoir 12 is provided upstream of the orifice 4d, the brake fluid in the liquid reservoir 12 is smoothly supplied to the wheel cylinder WC without being throttled by the orifice 4d when the pressure is increased.

(Embodiment 3) This embodiment 3 is a modification of the embodiment 1, and this embodiment 3 supplies the main pump 4 with brake fluid during automatic braking control. This is an example in which the pumping is performed directly using the feeding piston 30 instead of directly using the pump 8. That is, in the charging piston 30, the cylinder 31 is defined by the piston 32 into the charging chamber 33 and the pressure chamber 34. The charging chamber 33 is connected to the suction side of the main pump 4 via the charging circuit 8a. On the other hand, the pressure chamber 34 is connected to a pressure circuit 41 connected to the discharge side of the feed pump 8. Therefore, in the third embodiment, when the feeding pump 8 is driven, the brake fluid is introduced into the pressure chamber 34 of the feeding piston 30, whereby the piston 32 strokes and the brake fluid in the feeding chamber 33 passes through the feeding circuit 8 a. And is supplied to the main pump 4. The pressure pump 41 is connected to the reservoir tank RT of the master cylinder MC via a suction circuit 42, and the pressure circuit 41 is connected to the suction circuit 42 via a relief circuit 44 having a relief valve 43. 41 is configured not to exceed a predetermined pressure. Also, the relief circuit 4
A circulation circuit 45 that connects the pressure circuit 41 and the suction circuit 42 is provided in parallel with the circuit 3, and a circulation opening / closing valve 46 is provided in the circulation circuit 45.

The circulation opening / closing valve 46 is a normally open solenoid valve, and is configured to be closed only when the automatic braking control is performed. Therefore, when the motor M is driven and the charging pump 8 is driven during the ABS control, the charging pump 8 only circulates the brake fluid through the circulation circuit 45, does not perform any substantial work, and does not perform the substantial work. No brake fluid is supplied to the pressure chamber 34, and no energy is consumed in the feed pump 8.

(Embodiment 4) FIG. 9 is an example in which the charging structure using the charging piston 30 of Embodiment 3 is applied to the brake device of Embodiment 2, and the same operation and effect as those of Embodiments 2 and 3. Is obtained.

Although the embodiment has been described with reference to the drawings, the present invention is not limited to this embodiment. For example, in the embodiment, the inflow valve 5 and the outflow valve 6 serve as hydraulic pressure control valves. The above-mentioned two valves are shown, but the wheel cylinder WC side is provided with a brake circuit 1 (2),
One valve having a structure selectively connected to the drain circuit 10 may be used. Further, in the embodiment, the pumps 4 and 8 are of a plunger type, but other types of pumps such as a vane pump can be applied.

[0038]

As described above, according to the present invention, in a brake device capable of automatic braking control, a part of a brake circuit surrounded by an outside gate valve, a relief valve, a hydraulic control valve, and a main pump. And a relief reservoir for accumulating a predetermined amount of brake fluid is provided in the relief target portion, which is a part of the recirculation circuit, so that the circuit of the relief target portion can be increased without increasing the circuit length of the relief target portion. Increased brake fluid volume has the effect of improving the boosting performance of the wheel cylinder during automatic braking control, and the main pump's pulse pressure is absorbed by the reservoir, improving sound and vibration performance. The effect is obtained. Further, by improving the boosting performance described above, during automatic braking control, a wheel that is controlled to a low pressure from a state in which a plurality of wheel cylinders are controlled to a high pressure and a plurality of wheel cylinders is controlled to a low pressure. When increasing the pressure of the cylinder, it is possible to prevent the brake fluid of the high-pressure wheel cylinder from opening to the check valve and flowing out to the low-pressure wheel cylinder due to the shortage of the brake fluid. , And controllability and stability of the vehicle are improved. According to the second and third aspects of the invention, a plunger type pump is used as the main pump, and the brake fluid is not supplied to the relief target portion when the main pump is performing the suction stroke. However, in the invention according to the second aspect, the volume q3 required to increase the pressure of the low-pressure wheel cylinder per time required for one rotation of the motor by the volume of the liquid reservoir is determined by the wheel cylinder at the time of the relief pressure. (Q1-q), which is obtained by subtracting the wheel cylinder consumption liquid amount q2 at wheel lock hydraulic pressure from the consumption liquid amount q1
2) In the invention according to claim 3, the pump discharge amount q4 per one rotation of the motor is calculated from the consumption amount q1 of the wheel cylinder at the time of the relief pressure by the wheel at the time of the wheel lock hydraulic pressure. Since it is set to be equal to or less than the amount (q1-q2) obtained by subtracting the cylinder consumption liquid amount q2,
In the automatic braking control, when increasing the pressure of the low-pressure wheel cylinder among the plurality of wheel cylinders, even if the pressure of the wheel cylinder is increased from the atmospheric pressure to the maximum lock hydraulic pressure, until the main pump performs the next discharge. The brake fluid required for supply can be covered by the brake fluid stored in the reservoir, and the brake fluid does not flow from the high-pressure wheel cylinder to the low-pressure wheel cylinder.
The effect of improving controllability and stability of the vehicle is obtained. According to the fourth aspect of the present invention, the discharge pulse pressure of the main pump can be reliably absorbed by the damper and the orifice, and when the pressure of the wheel cylinder is increased, the brake fluid in the liquid reservoir is not throttled by the pulse pressure absorbing orifice. It is supplied to the cylinder, and the same effects as those of the first to third aspects of the invention are obtained. According to the invention of claims 5 to 7, since the supply circuit is provided with the supply means and the supply means supplies the brake fluid to the main pump, the supply of the brake fluid to the main pump is made smooth. In addition to the effects similar to those of the inventions described in (4) to (4), the effect is obtained that the main pump is configured to have a small size and a small capacity so that the device can be downsized and control responsiveness can be secured.

[Brief description of the drawings]

FIG. 1 is a view corresponding to claims showing a brake device of the present invention.

FIG. 2 is an overall view showing a brake device according to Embodiment 1 of the present invention.

FIG. 3 is a characteristic diagram of a consumed liquid amount and a pressure of the wheel cylinder according to the first embodiment.

FIG. 4 is a block diagram of the first embodiment.

FIG. 5 is a flowchart of an ABS control according to the embodiment.

FIG. 6 is a flowchart of automatic braking control according to the embodiment.

FIG. 7 is an overall view showing a brake device according to a second embodiment.

FIG. 8 is an overall view showing a brake device according to a third embodiment.

FIG. 9 is an overall view showing a brake device according to a fourth embodiment.

[Explanation of symbols]

 WC (FL) Wheel cylinder WC (RR) Wheel cylinder WC (FR) Wheel cylinder WC (RL) Wheel cylinder MC Master cylinder BP Brake pedal RT Reservoir tank CU Control unit S Wheel speed sensor YR Yaw rate sensor H Steering angle sensor BS Brake sensor GS G sensor SG sensor group BU Brake unit 1 Brake circuit 1b Gate valve bypass circuit 1c One-way valve (check valve) 1d, 1e Branch point 1f Front wheel branch circuit 1g One-way valve (check valve) 1h Inflow valve bypass circuit 1m Relief circuit 1r After Wheel branch circuit 2 Brake circuit 3 Out side gate valve 4 Main pump 4a Reflux circuit 4b Discharge valve 4c Damper 4e Compression chamber 4h Suction valve 4j Branch point 4p Plunger 5 Inflow valve (hydraulic pressure control valve) 6 Outflow valve (liquid) Control valve) 7 Reservoir 8 Supply pump 8a Supply circuit 8b Discharge valve 8c Suction valve 8d Branch point 8e Compression chamber 8p Plunger 9 In side gate valve 10 Drain circuit 11 Camshaft 12 Liquid reservoir 20 Relief valve 30 Supply piston 31 Cylinder 32 Piston 33 Supply chamber 34 Pressure chamber 41 Pressure circuit 42 Suction circuit 43 Relief valve 44 Relief circuit 45 Circulation circuit 46 Circulation on-off valve

Claims (7)

[Claims] 1. A state in which a wheel cylinder is connected to a master cylinder side in the middle of a brake circuit connecting a master cylinder and a plurality of wheel cylinders, a state in which the wheel cylinder is connected to a reservoir via a drain circuit, A hydraulic pressure control valve for forming a state in which the cylinder is shut off from both the master cylinder and the reservoir and controlling the hydraulic pressure of each wheel cylinder is provided, and the reservoir and the master cylinder side with respect to the hydraulic pressure control valve of the brake circuit are provided. A main pump that discharges the brake fluid of the reservoir to the brake circuit is provided in the middle of the recirculation circuit to be connected, a charging circuit that can supply the brake fluid to the suction side of the main pump is connected, and an inlet and outlet that opens and closes the charging circuit. A side gate valve, a discharge position of the main pump in the brake circuit, a master cylinder, An out-side gate valve for opening and closing the brake circuit is provided in between, and in parallel with the out-side gate valve, the valve opens and brakes when the fluid pressure downstream of the out-side gate valve exceeds a predetermined pressure. A relief valve for releasing fluid to the upstream side of the out-side gate valve is provided. The brake circuit includes a check valve for returning the brake fluid of the wheel cylinder to the master cylinder in parallel with the hydraulic pressure control valve and the out-side gate valve. Irrespective of whether the driver is performing the braking operation or not, the main pump discharges the brake fluid from the charging circuit to the brake circuit, and supplies this brake fluid to the wheel cylinder by the hydraulic pressure control valve. A braking device configured to automatically generate a braking force, wherein the main pump, the out-side gate valve, the relief valve, and the fluid A brake device, wherein a fluid reservoir for accumulating a predetermined amount of brake fluid is provided in a relief target portion including a brake circuit and a part of a recirculation circuit surrounded by a pressure control valve. 2. A plunger type in which a plunger performs a reciprocating stroke with a rotation of a motor to suck and discharge brake fluid as the main pump, and the volume of the liquid reservoir is one rotation of the motor. The amount q3 required to increase the pressure of the wheel cylinder from the low pressure state per the time required to perform the pressure reduction is subtracted from the amount q1 of the consumed wheel cylinder liquid at the time of the wheel lock hydraulic pressure from the amount q1 of the consumed wheel cylinder liquid at the time of the relief pressure. The braking device according to claim 1, wherein the braking force is set so as to be equal to or less than (q1-q2). 3. A plunger of a plunger type in which a plunger performs a reciprocating stroke with a rotation of a motor to suck and discharge brake fluid as the main pump, and a volume of the liquid reservoir per one rotation of the motor is used. The pump discharge amount q4 of the wheel cylinder is changed from the consumed amount q1 of the wheel cylinder at the time of the relief pressure to the consumed amount q of the wheel cylinder at the time of the wheel lock hydraulic pressure.
2. The brake device according to claim 1, wherein the brake device is set to be equal to or less than an amount (q1-q2) obtained by subtracting 2. 4. A damper for absorbing pulse pressure and an orifice are provided in order from the main pump side on the discharge side of the main pump of the return circuit, and the liquid reservoir is located on the brake circuit side of the return circuit in the return circuit with respect to the orifice. The brake device according to claim 1, wherein the brake device is provided. 5. The brake device according to claim 1, wherein the supply circuit is provided with a supply unit that sends the brake fluid toward a suction side of the main pump. 6. The supply circuit is connected to a master cylinder side, and the supply means is constituted by a supply pump provided in the supply circuit and discharging the brake fluid on the master cylinder side to the main pump. The brake device according to claim 5, wherein 7. The supply means includes a supply piston slidably provided with a piston defining a supply chamber and a pressure chamber inside the cylinder, and a pressure chamber for sucking brake fluid on the master cylinder side. The brake device according to claim 5, further comprising: a supply pump that discharges a pressure circuit connected to the supply circuit, wherein the supply chamber is connected to the supply circuit.