JPH1191547A - Passage switching valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accumulate pressure in an accumulator utilizing brake hydraulic pressure generated in a circuit in a normal using state. SOLUTION: Hydraulic fluid flows from first port 14a communicating with a hydraulic source to second port 14b communicating with an actuator via a check valve 14m and an orifice 14n. When no hydraulic pressure from the hydraulic source operates, a passage switching piston 14e is moved by hydraulic pressure difference generated at both ends of the passage switching piston 14e by the orifice 14n so that the second port 14b and third port 14c communicating with an accumulator communicate with each other so as to accumulate pressure in the accumulator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow path switching valve suitable for a brake fluid pressure control device having an automatic braking function of automatically operating a brake under predetermined conditions to brake a vehicle, In particular, when the vehicle moves while parked unmanned, when the distance between vehicles is reduced during normal driving, or when approaching an obstacle, the flow path switching suitable for a brake fluid pressure control device that automatically activates the brake. It is about a valve.

[0002]

2. Description of the Related Art Conventionally, there has been known an automatic brake device disclosed in Japanese Patent Application Laid-Open No. Hei 6-107141. The automatic brake device described in the above publication is provided with a preliminary pressurizing unit, and by switching an electromagnetic valve in a hydraulic circuit, supplies the pressurized fluid stored in the pressurizing unit to the wheel cylinder, thereby applying a brake. It is working.

[0003]

However, in the above-mentioned automatic brake device, since the accumulator used as the pre-pressurizing means is of a high pressure and high capacity type, the volume of the pressurizing means (accumulator) is usually high. However, there are problems such as an increase in weight and an increase in cost, and there is a demand for improvement in terms of weight reduction of the vehicle body and reduction of cost.

In order to solve the above-mentioned problems, the present invention uses a small-sized low-pressure accumulator instead of the conventional high-pressure, high-capacity accumulator.
At the time of automatic braking, the hydraulic pump is operated so that the brake fluid can be quickly supplied to the wheel cylinder in accordance with the hydraulic pressure from the small accumulator, ensuring responsiveness and increasing the hydraulic pressure in the wheel cylinder when the brake is released. It is an object of the present invention to provide an automatic brake device including a flow path switching valve capable of accumulating pressure in a small and low-pressure accumulator.

According to the present invention, a small and low-pressure accumulator is provided in a hydraulic circuit, and in this accumulator, a flow path switching valve is switched by using a brake fluid pressure generated in the circuit in a normal use state to constantly accumulate pressure. In addition, at the time of automatic braking, the brake fluid from the accumulator is pumped up by the hydraulic pump to enable the brake operation, and the cut valve and the self-keep valve that cut off the communication with the master cylinder in the circuit. When a predetermined hydraulic pressure is generated in the circuit, the self-keeping valve automatically shuts off the circuit, so that the hydraulic pressure can be maintained even when the cut valve is de-energized. For this reason, the accumulator used in the present apparatus can be of a small and low pressure that can accumulate the brake fluid pressure generated during normal operation.

[0006]

The technical solution adopted by the present invention includes a first port communicating with a hydraulic pressure source, a second port communicating with an actuator, a third port communicating with an accumulator, and A cylinder communicating with the port,
A flow path switching piston slidably provided in the cylinder and capable of cutting off communication between the second port and the third port, and allowing a flow of hydraulic pressure from the first port to the second port A check valve, the first port and the second
And an orifice communicating with the port. The hydraulic pressure from the hydraulic pressure source flows from the first port to the second port side via the check valve and the orifice, and the hydraulic pressure from the hydraulic pressure source stops working. In such a case, the flow path switching piston is moved by the hydraulic pressure difference generated at both ends of the flow path switching piston by the action of the orifice, and the second port and the third port are communicated with each other so that the pressure can be accumulated in the accumulator. Flow path switching valve.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of the brake fluid pressure control device, FIG. 2 is an enlarged sectional view of a self-keeping valve in the device, 3 is an enlarged sectional view of a flow switching valve (guaranty valve) in the apparatus, FIG. 4 is an enlarged sectional view of a low-pressure accumulator in the apparatus, and FIG. 5 is an enlarged sectional view of a hydraulic pump in the apparatus. 6 is a configuration diagram of an electronic control device in the device. Hereinafter, after describing the overall configuration of the brake fluid pressure control device, details of components of a self-keeping valve, a flow path switching valve (guaranty valve), a low-pressure accumulator, a fluid pressure pump, and an electronic control device that performs fluid pressure control are described. I will explain it.

As shown in FIG. 1, the brake circuit of this embodiment comprises two systems for a front wheel and a rear wheel. Each system is a hydraulic pressure source (master cylinder) 2 for generating a hydraulic pressure by depressing a brake pedal 1. And as shown in the illustration,
The automatic brake device, which is a feature of the present invention, is disposed on the rear wheel system. Note that the automatic brake device can be provided on the front wheel system side as needed.

The front wheel brake system includes a first cut valve 4, a hold valve 5, a decay valve 6, a front wheel hydraulic pump 7, a front wheel anti-lock control reservoir 8, and a damper 9 between the master cylinder 2 and the wheel cylinder 3.
An anti-lock control modulator consisting of, for example, is disposed. The first cut valve 4 is configured as a normally-open two-position switching valve, and a check valve 4 a is provided in parallel with the first cut valve 4. Further, the damper 9 is provided to alleviate kickback of the brake pedal during the anti-lock control. The damper 9 includes a damper piston 9b and a damper spring 9c in a damper cylinder 9a. The damper piston 9b is normally operated by the damper spring 9c. The liquid chamber 9 d is urged downward in the drawing to form a damper piston 9.
The liquid discharged from the front wheel hydraulic pump 7 can flow into the liquid chamber 9d defined by b.

The rear wheel brake system includes a master cylinder 2
Is connected to a first port 12a of a self-keeping valve 12 (detailed configuration will be described later), a second port 12b of the self-keeping valve 12 is connected to a pipeline 13, and in the same pipeline 13, A second cut valve 11 and a guarantee valve 14 as a normally-open two-position switching valve are arranged. A conduit 13 from the second cut valve 11 is connected to a fourth port 12d of the self-keep valve 12 and is connected to a first port 14a of a flow path switching valve 14 (hereinafter referred to as a guarantee valve and a detailed configuration will be described later). The second port 14b of the guarantee valve 14 is connected to the rear wheel cylinder 3 'via a hold valve 5', communicating with the discharge port 21b of the brake hydraulic pump 21.

A third port 14c of the guarantee valve 14 communicates with a port 15a of the low-pressure accumulator 15 and a discharge port 1 of a hydraulic pump 16 for a rear wheel.
6c and the second switching valve 18. A port 15 is provided in a flow path connecting the second port 14b of the guarantee valve 14 and the port 15a of the low-pressure accumulator 15.
A check valve 22 that allows the flow from the port a to the second port 14b is arranged.

The rear wheel cylinder 3 'is connected to a first suction port 16a of a rear wheel hydraulic pump 16 and a rear wheel anti-lock control reservoir 23 via a decay valve 6'. Rear wheel hydraulic pump 1 via pressure sensor 20 and first switching valve 17
No. 6 communicates with the second suction port 16b. The automatic brake hydraulic pump 21 is of a type driven by a motor (not shown) by a cam 24 common to the front wheel hydraulic pump 7 and the rear wheel hydraulic pump 16 described above. The suction port 21a of the low-pressure accumulator 15 communicates with the port 15a of the low-pressure accumulator 15 via the second switching valve 18, and the discharge port 21b of the second cut valve 11
And a line 13 communicating the guarantee valve 14 and a third port 12 c of the self-keeping valve 12 via a third switching valve 19. A relief valve 19 a for preventing the discharge pressure of the automatic brake hydraulic pressure pump 19 from becoming excessive is disposed in a pipe provided in parallel with the third switching valve 19.

The above-mentioned first switching valve 17, second switching valve 18,
Each of the third switching valves 19 is configured as a normally closed two-position switching valve, and the second cut valve 11 is a check valve 11a.
, And is configured to open and close the flow path in response to a command from the electronic control unit. The liquid recirculation type anti-lock control modulator (5,
5 ', 6, 6', 7, 16, 8, 23) are conventionally known ones. In the front wheel system and the rear wheel system, various valves, switching valves, hydraulic pumps, and the like in the above-described configuration are commanded from an electronic control device that operates based on signals from various sensors that detect the state of the vehicle body. Executes anti-lock control or automatic brake control.

Next, components such as the self-keeping valve 12, the guarantee valve 14, the low-pressure accumulator 15, the hydraulic pumps 7, 16, 21 and the electronic control unit will be described in detail. [Self-keeping valve 12] As shown in FIG. 2, the self-keeping valve 12 has a first port 12a, a second port
It has a port 12b, a third port 12c, and a fourth port 12d, and a self-keeping piston 12f is slidably disposed in a cylinder 12e communicating these.
The self-keeping piston 12f is biased rightward in the figure by a return spring 12h, and the self-keeping piston 12f is provided with a valve element 12g, which resists the urging force of the return spring 12h. Then, by moving to the left and contacting the left wall surface of the cylinder 12e, the first port 12a (and the third port 1
The communication between 2c) and the second port 12b is interrupted. Further, the self-keeping piston 12f is in contact with the small-diameter piston 12i arranged in the fourth port 12d, and the hydraulic pressure acting on the fourth port 12d becomes a predetermined value (P1
= F / A, where F is the force of the return spring, and A is the pressure receiving area of the small diameter piston 12i), the small diameter piston 12i and the self-keeping piston 12f move to the left while bending the return spring 12h, and the first
The communication between the port 12a, the third port 12c and the second port 12b is cut off.

[Guarantee Valve 14] As shown in FIG. 3, the guarantee valve 14 has a first port 14a, a second port 14b, and a third port 14c in a valve body, and a flow switching piston (hereinafter referred to as a piston) in a cylinder 14d. A guarantee piston 14e is slidably disposed, and the guarantee piston 14e is
It is urged leftward in the figure by a return spring 14f disposed in the position d. The guarantee piston 14e is provided with a valve body 14g, and the valve body 14g contacts the left wall surface of the cylinder 14d, so that the second port 1
The communication between the fourth port 4b and the third port 14c is interrupted. In the third port 14c, there is provided a first check valve 14h that cuts off the communication from the third port 14c toward the second port 14b by the urging force of a spring.
The check valve 14h has a function of allowing a flow from the second port 14b to the third port 14c.

A passage 14i is formed in the guarantee piston 14e. The passage 14i communicates with the second port 14b through a gap 14k formed around the guarantee piston 14e, and also communicates with the first port 14a. A second check valve 14m composed of a spring and a ball is disposed in the passage 14i. The second check valve 14m has a function of allowing a flow from the first port 14a to the second port 14b. The first port 14a and the second port 14b communicate with each other through an orifice 14n as shown in the figure.

In the state shown, the guarantee valve 14 blocks the communication between the second port 14b and the third port 14c, and when the hydraulic pressure of the master cylinder 2 flows in from the first port 14a side. , 2nd check valve 1
Hydraulic pressure can be discharged to the wheel cylinder 3 'through the 4m, the orifice 14n and the second port 14b. Further, when the hydraulic pressure on the second port 14b side increases, a hydraulic pressure difference is generated between the left and right end surfaces of the guarantee piston 14e by the action of the orifice 14n, and the guarantee piston 14e moves rightward in the figure to open the valve body 14g. The hydraulic pressure can flow out from the second port 14b to the third port 14c via the first check valve 14h.

[Low-pressure accumulator 15] As shown in FIG. 4, the low-pressure accumulator 15 has a hydraulic chamber 15c defined by an accumulator piston 15b slidably disposed in the accumulator main body, and the hydraulic chamber 15c has a port 15a. Via the second switching valve 18 and the third port 14c of the guarantee valve 14 and the check valve 2
2 through the second port 14b. The accumulator piston 15b is constantly urged rightward in the figure by the urging force of a spring 15d, and the accumulator piston 15b has a detection rod 15 for detecting a position.
e is provided, and the end of the detection rod 15e is in contact with the limit switch 15f.

The low-pressure accumulator 15 maintains the initial state indicated by the dotted line in the figure when the hydraulic pressure is not acting on the hydraulic chamber 15c (for example, at the time of shipment), and when the brake is released from the brake operating state. Wheel cylinder 3 '
The internal fluid pressure flows into the fluid pressure chamber 15c, and the accumulator piston 15b is moved to the left in the figure to accumulate a predetermined fluid pressure in the fluid pressure chamber 15c in the state shown in the drawing. When the accumulator piston 15b comes to the left position (accumulated state) as shown, the state can be detected by the limit switch 15f.

[Hydraulic Pumps 7, 16, 21] As shown in FIG. 5, the hydraulic pumps 7, 16, 21 for the front wheels, the rear wheels, and the automatic brakes have a conventionally known plunger type hydraulic pressure pump. The pump is a pump, and the respective pistons 7a, 16e, 21e reciprocate by rotating the cam 24 to pump up liquid from the suction ports 7b, 16a, 16b, 21a and discharge liquid from the discharge ports 7c, 16c, 21b. Things. However, the rear wheel hydraulic pump 16 is a conventional ABS.
The configuration is different in that a second suction port 16b for automatic brake control, which is a feature of the present invention, is provided in addition to the first suction port 16a for control, but the function of the pump is not changed.

[Electronic control device]
The electronic control unit includes a wheel speed sensor (Vw), a brake switch (SW), a clutch switch (SW), a parking switch (SW), a gear switch (SW), a limit switch (15f), a pressure switch, as shown in FIG. A signal from the sensor 20 is input, and the brake is automatically activated when the vehicle moves during unmanned parking while the vehicle is stopped, or when the inter-vehicle distance is reduced during normal driving.

The operation of the brake fluid pressure control device configured as described above will be described. [Normal brake operation (anti-lock non-control state)]
When the driver steps on the brake pedal 1 and generates hydraulic pressure in the tandem master cylinder 2, the hydraulic pressure in the front wheel brake system is changed from the first open cut valve 4 → the open hold valve 5 → the front wheel cylinder 3 And the brake is activated. In the rear wheel brake system, the first port 12a of the self-keep valve 12 → the second port 12b → the second cut valve 11 which is open → the first port 14a of the guarantee valve 14 → the second check valve 14m in the guarantee piston 14e. → Gap 14k around piston → 2nd port 14 of guarantee valve 14
b and the first port 1 of the guarantee valve 14
4a → orifice 14n → supplied to the rear wheel cylinder 3 ′ via the hold valve 5 ′ via the second port 14b of the guarantee valve 14 to operate the brake. At this time, the third switching valve 19 is in the closed state. Since the valve body 14g provided on the guarantee piston 14e abuts on the left wall surface of the cylinder to interrupt the communication between the second port 14b and the third port 14c, the guarantee valve 14 is connected to the second port 14b of the guarantee valve 14. The communication with the third port 14c is shut off.

When the driver releases the brake pedal 1,
In the front wheel brake system, the hydraulic pressure in the wheel cylinder 3 is recirculated to the master cylinder 2 through a route reverse to that described above, and the brake is released. In the rear wheel brake system, the hydraulic pressure of the wheel cylinder 3 ′ is returned to the master cylinder 2 because the second check valve 14 m is provided.
4n only. Due to the interposition of the orifice 14n, a hydraulic pressure difference is generated between both ends of the guarantee piston 14e, and the hydraulic pressure causes the guarantee piston 14e to move rightward in the drawing to move the valve body 14g away from the wall surface, and the second port 14b of the guarantee valve 14 And the third port 14c
Communicates via the first check valve 14h in the third port 14c, and the hydraulic pressure in the wheel cylinder 3 'flows into the low-pressure accumulator 15.

When the difference in hydraulic pressure acting on the guarantee piston 14e decreases, the guarantee piston 14e returns to the initial state again, and the residual pressure in the wheel cylinder 3 'is changed to the orifice 14n in the guarantee valve 14 → the first port 14a of the guarantee valve 14 → Open second cut valve 11 → second port 12 of self-keep valve 12
b → recirculates to the master cylinder 2 via the first port 12a. In this state, the self-keep valve 1
Since the same hydraulic pressure acts on both ends of the small-diameter piston 12i in 2, the small-diameter piston 12i does not move. Each time the brake operation is released, the hydraulic pressure in the wheel cylinder 3 'is accumulated in the low-pressure accumulator 15, and this accumulated pressure is monitored by the limit switch 15f. 15f is turned on.

[At the time of anti-lock control] If the wheels tend to lock during the above-mentioned brake operation, the hold valves 5, 5 'close and the decay valves 6, 6'.
Is opened to return the brake fluid in the wheel cylinders 3 and 3 'to the anti-lock control reservoirs 8 and 23, and at the same time, the hydraulic pumps 7 and 16 are operated to pump up the brake fluid in the reservoir and to return to the master cylinder 2 to brake. The control of the hydraulic pressure is executed to eliminate the locking tendency. The control mode of the hold valves 5, 5 'and the decay valves 6, 6' in this state is the same as that of the conventional antilock control.

At the time of the anti-lock control, in the front-wheel anti-lock control modulator, the liquid discharged from the front-wheel hydraulic pump 7 also flows into the damper 9, and as a result, the damper 9
By the function, kickback of the brake pedal can be reduced. In the rear wheel anti-lock control modulator, the discharge liquid of the rear wheel hydraulic pump 16 is stored in the low-pressure accumulator 15 while passing through the check valve 22 → the guarantee valve 14 → the second cut valve 11 → the self-keep valve 12. Reflux to master cylinder 2.

[Automatic Brake Operation] As an example, the automatic brake control when the vehicle moves on a slope because the pulling force of the parking brake is weak during unmanned parking will be described with reference to the time chart of FIG. [Pressure increase] When the vehicle is stopped unattended, the parking brake is applied, the clutch pedal is not operated, the gear is in neutral, and the sensors detect that the vehicle speed has exceeded a predetermined value. The (ECU) issues a command to operate the automatic brake as follows. When the automatic brake operation command is issued, first, as shown in FIGS. 7 and 9, the second cut valve 11 is closed, and then, after a slight time difference ΔT, the second switching valve 18 opens the flow path and simultaneously drives the hydraulic pump. When the motor is started, the automatic brake hydraulic pump 21 operates.

As a result, the hydraulic pressure in the low-pressure accumulator 15 is increased by the second switching valve 18, the check valves 21 c and 21 d in the pump 21, and the first and second valves of the guarantee valve 14.
It is transmitted to the rear wheel cylinder 3 'promptly through the ports 14a, 14b and the hold valve 5' to fill the brake clearance of the rear wheel brake and bring the brake operation to an initial state. Thereafter, when the hydraulic pump 21 substantially starts operating, the liquid in the low-pressure accumulator 15 is boosted and discharged from the discharge port 21b, transmitted to the wheel cylinder 3 'via the above-described route, and the braking force is increased. . At this time, when the pressure of the low-pressure accumulator 15 is reduced to a predetermined hydraulic pressure P2, the limit switch 15f is turned on. Thus, the motor rotates and the hydraulic pump 2
Since the hydraulic pressure in the low-pressure accumulator 15 can be transmitted directly to the wheel cylinder 3 'until the 1 discharges the effective hydraulic pressure, the responsiveness is improved. When the automatic brake is activated, the display lamp L in the driver's seat is turned on.

Then, the wheel cylinder pressure becomes a predetermined value P3
In the rear wheel brake system, the second cut valve 11 and the second switching valve 1
8, the second cut valve 11 is opened,
The second switching valve 18 is closed, and the driving of the motor is stopped. In this state, in the self-keeping valve 12, since the hydraulic pressure is acting on the fourth port 12d, the small-diameter piston 12i and the self-keeping piston 12f are moved leftward in the figure by this hydraulic pressure to move the valve body 12g. close. The second port 12b and the first port 12a of the self-keep valve 12
, The brake fluid in the wheel cylinder 3 ′ does not return to the master cylinder 2 even if the second cut valve 11 is opened thereafter. Therefore, when the hydraulic pressure in the wheel cylinder reaches the predetermined value P3, it is not necessary to continue energizing the second cut valve 11, and the energizing time to the second cut valve 11 can be controlled within the rated time, and the power saving effect can be achieved. And the durability of the valve 11 can be increased. In order to prevent the brake fluid pumped during automatic braking from excessively pressurizing the wheel cylinder 3 'side for any reason, when the discharge fluid pressure becomes a predetermined value or more, the relief valve 19a opens and the brake fluid is discharged. Third port 1 of self-keeping valve 12
2c → master cylinder 2 via the first port 12a
Reflux.

[Depressurization] When a pressure-reducing command for the automatic brake (for example, when the parking brake is released and the brake pedal is depressed) is issued, as shown in FIGS.
The cut valve 11 is closed, and after a slight time difference ΔT, the first switching valve 17 opens the flow path, the motor for driving the hydraulic pump is started, and the hydraulic pump 16 for the rear wheels operates.

As a result, in the rear wheel brake system, as shown by the solid arrow in the figure, the first switching valve 1 in which the rear wheel hydraulic pump 16 opens the brake fluid in the wheel cylinder 3 '.
, The pressure in the wheel cylinder is reduced while the pressure in the low-pressure accumulator 15 is accumulated through the discharge port 16c. Thereafter, the hydraulic pressure of the low-pressure accumulator 15 becomes P
When it reaches 2, the limit switch 15f is turned off, and based on the signal, the second cut valve 11 is opened, the first switching valve 17 is closed, the third switching valve 19 is opened, and the motor Stop driving.

As a result, the residual pressure in the wheel cylinder is
As shown by the dotted arrow in the figure, the hold valve 5 '→ the second port 14b of the guarantee valve 14 → the orifice 14n in the guarantee valve 14 → the first port 14a of the guarantee valve → the stopped automatic brake hydraulic pump 21. Then, the fluid returns to the master cylinder 2 through the discharge port 21b → the opened third switching valve 19 → the third port 12c of the self-keeping valve 12 → the first port 12a, and the brake fluid pressure is completely released. The self-keeping valve 1 is activated when the fluid pressure becomes
2 is open. Then, after a lapse of a predetermined time after the motor stops (sufficient time until the residual pressure in the wheel cylinder becomes zero), the third switching valve 19 returns to the initial closed state.
The timing of opening the second cut valve 11, closing the first switching valve 17, opening the third switching valve 19, and further stopping the motor is not limited to the signal from the limit switch 15f. The valve, the valve, and the motor may be switched by detecting that the hydraulic pressure in 3 ′ has become equal to or lower than a predetermined hydraulic pressure by the pressure sensor 20 or by detecting that a predetermined time has elapsed after the operation of the motor.

[Brake pressure holding control at the time of temporary stop] Also, even if the brake pedal is released when the vehicle is temporarily stopped on a slope while driving, the brake pressure is held and released by the driver's starting operation. This makes it easy to start on a hill and reduces the burden on the driver. In this case, the automatic brake operates as follows. When the vehicle stops and a predetermined time elapses, the state is detected by a signal from a wheel speed sensor Vw, and first, as shown in FIG.
Close 1. Thereafter, even when the brake pedal is released, the hydraulic pressure of the wheel cylinders 3, 3 'is maintained. When the brake pedal is released, the pressure in the master cylinder 2 becomes zero, so that the small-diameter piston 12i moves to the left by the hydraulic pressure of the wheel cylinder 3 'to cut off the communication between the first port 12a and the second port 12b. Thus, the brake pressure at the time of the temporary stop is maintained.

[Brake Pressure Release During Temporary Stop] When a brake release command is issued, that is, when the electronic control unit detects the starting state of the vehicle based on a signal from a sensor such as a clutch switch or a gear switch, the first operation is performed. The cut valve 4, the second cut valve 11, and the third switching valve 19 are opened. As a result, in the front wheel brake system, the brake fluid in the wheel cylinder 3 recirculates to the master cylinder 2 via the open hold valve 5 → open first cut valve 4, and the brake fluid pressure is reduced.

In the rear wheel brake system, the hold valve 5 '→ the second port 14b of the guarantee valve 14
→ Orifice 14n in guarantee valve 14 → 1st
The port 14a → the discharge port 21b of the automatic brake hydraulic pump 21 → the open third switching valve 19 → the third port 12c of the self-keeping valve 12 → the hydraulic pressure of the wheel cylinder 3 ′ via the first port 12a It returns to the master cylinder 2 to release the brake fluid pressure completely. in the meantime,
When the hydraulic pressure of the wheel cylinder 3 'falls below the predetermined value P1, the self-keep valve 12 opens, and the wheel cylinder 3'
Is returned to the master cylinder via the self-keep valve 12 as well. Then, when the pressure detected by the pressure sensor 20 is zero or a predetermined time has elapsed after the release command of the brake pressure is issued, the third switching valve 19 returns to the closed state (initial state).

The brake fluid pressure control device according to the present invention can operate the automatic brake not only when the vehicle moves in an unmanned state, but also when the inter-vehicle distance to the preceding vehicle becomes a predetermined value or less. In that case, it can be easily implemented by providing an inter-vehicle distance sensor. Further, the various sensors described in the embodiment and the manner of processing their signals are not features of the present invention, and various known sensors and signal processing means can be applied to the brake fluid pressure control device according to the present invention.

[0037]

As described above in detail, according to the present invention, 1) the accumulated hydraulic pressure of the accumulator 15 when the brake is released can be immediately transmitted to the wheel cylinder 3 'upon the start of the automatic brake control. Therefore, a brake operation with good responsiveness can be obtained despite the operation delay of the hydraulic pump. 2) Since the low-pressure accumulator 15 can be used, the size and weight of the device can be reduced, and the cost can be reduced. 3) The low-pressure accumulator 1 utilizes the hydraulic pressure of the wheel cylinder 3 'when the brake is released by the action of the flow path switching valve.
A predetermined hydraulic pressure can always be stored in the storage unit 5. And the like.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a brake fluid pressure control device having an automatic brake function according to the present embodiment.

FIG. 2 is an enlarged sectional view of a self-keeping valve 12 in the brake fluid pressure control device.

FIG. 3 is an enlarged sectional view of a guarantee valve 14 in the brake fluid pressure control device.

FIG. 4 is an enlarged sectional view of a low-pressure accumulator 15 in the brake fluid pressure control device.

FIG. 5 is an enlarged sectional view of a hydraulic pump in the brake hydraulic pressure control device.

FIG. 6 is a configuration diagram of an electronic control device in the brake fluid pressure control device.

FIG. 7 is a diagram showing an automatic brake pressure increasing state by the brake fluid pressure control device.

FIG. 8 is a diagram showing an automatic brake pressure reduction state by the brake fluid pressure control device.

FIG. 9 is a time chart of automatic braking by the brake fluid pressure control device.

FIG. 10 is a diagram showing a brake pressure holding control state when the vehicle is stopped by the present brake fluid pressure control device.

[Explanation of symbols]

Reference Signs List 1 brake pedal 2 master cylinder 3, 3 'wheel cylinder 4 first cut valve 5, 5' hold valve 6, 6 'decay valve 7 front wheel hydraulic pump 8 front wheel anti-lock control reservoir 9 damper 11 second cut valve 12 Self-keeping valve 13 Pipe line 14 Flow path switching valve (guaranty valve) 15 Low pressure accumulator 16 Rear wheel hydraulic pump 17 First switching valve 18 Second switching valve 23 Rear wheel anti-lock control reservoir 20 Pressure sensor 21 Automatic brake fluid Pressure pump

Claims (2)

[Claims] A first port connected to a hydraulic pressure source; a second port connected to an actuator; a third port connected to an accumulator; a cylinder connected to each of the ports; The second port 14b and the third port 14
c, a flow path switching piston 14e capable of blocking communication with the first port 14a and the second port 14b
A check valve 14m that allows the flow of hydraulic pressure to the side, and an orifice 14n that communicates with the first port 14a and the second port 14b. The hydraulic pressure from a hydraulic pressure source is supplied from the first port 14a to the first port 14a. Check valve 1 on 2 port 14b side
4m and orifice 14n,
When the hydraulic pressure from the hydraulic pressure source stops working, the flow path switching piston 14e is moved by the hydraulic pressure difference generated at both ends of the flow path switching piston by the action of the orifice 14n, and the second port 14b and the third port 14c are moved. Characterized in that the pressure can be accumulated in the accumulator. 2. The system according to claim 1, wherein the flow path switching valve is connected to the second port.
a spring 14f pressing the flow path switching piston 14e to cut off the communication between the third port 14c and the third port 14c.
And a valve element 14g, wherein the valve element 14g is configured to cut off communication between the second port 14b and the third port 14c. .