JPH0971235A - Brake fluid pressure control device of antiskid control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the residual pressure of the brake fluid in a wheel cylinder in the pressure reducing operation time of a skid control, as well as to realize to simplify the circuit structure and to reduce the manufacture cost. SOLUTION: In a pressure reducing operation time of the antiskid control making a solenoid valve 38 in the opening condition, a plunger 54 moves to a position to communicate both the second feed passage and an exhaust passage to a throttle passage 54g. By the movement of the plunger 54, the first throttle 42 and the second throttle 52 are provided in series to the flowing-in passage of the brake fluid between a master cylinder 20 and a wheel cylinder 22FL. And to the flowing-out passage of the brake oil to communicate the wheel cylinder 22FL and a reservoir tank 34, only the second throttle 52 is provided. Consequently, the partial pressure ratio of the flowing-in passage and the flowing-out passage of the circuit is reduced, and the brake fluid hardly remains in the wheel cylinder at the final stage of the pressure reducing operation condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake fluid pressure control device for an anti-skid control device that controls a brake fluid pressure during braking of a vehicle to suppress a sudden increase in the amount of wheel slip.

[0002]

2. Description of the Related Art Various brake fluid pressure control devices equipped with anti-skid control have been developed. The basic structure is based on the wheel cylinders provided on each wheel and the depression of the brake pedal. An actuator is provided between the master cylinder that outputs the brake fluid pressure, and by operating this actuator, the brake fluid supplied to the wheel cylinder is increased or reduced in pressure, thereby controlling the brake fluid pressure, that is, the braking force. Prevent the lock state from occurring.

As a conventional actuator for increasing / decreasing the pressure of a brake fluid, for example, a device disclosed in Japanese Patent Laid-Open No. 4-154462 is known (hereinafter referred to as Prior Art 1). This prior art 1 is, as shown in FIG. 6, a master cylinder 1 and a brake cylinder (wheel cylinder) 2
And a first supply passage L ₁ communicating with the first supply passage L _1.
A shut-off valve 3 arranged in _1; a sump device (reservoir tank) 4 for discharging the brake fluid supplied to the brake cylinder 2; and a discharge passage L ₂ for connecting the brake cylinder 2 and the sump device 4 to each other. , A pump 5 for pumping and returning the brake fluid stored in the sump device 4 to the first supply passage L ₁ side, and a normally closed two-way solenoid valve 6 provided in the discharge passage L _2.
A second supply passage L ₃ bypassing the shutoff valve 3 and connected to the first supply passage L _1, and a brake fluid from the pump 5 side to the brake cylinder 2 arranged in the second supply passage L _3. The first orifice 7 that restricts the flow of the fluid, the second orifice 8 that is provided in the discharge passage L ₂ , and the second supply passage L ₃ that connects or disconnects the discharge side of the pump 5 and the brake cylinder 2. And a flow path switching valve 9 for switching. Then, the pressure P ₁ on the upstream side of the second orifice 8 is guided to one end face of the flow path switching valve 9 via the pilot passage 8a, and the pressure P ₂ on the downstream side of the flow path switching valve 9 via the pilot passage 8b. The flow path switching valve 9 is guided to the other end surface, and the flow path switching valve 9 is controlled to move when a pressure difference (ΔP = P ₁ -P ₂ ) is generated.

During depressurization operation during anti-skid control, the flow path switching valve 9 moves to position E in FIG. 6, and the discharge side of the master cylinder 1 and pump 5 and the brake cylinder 2 are moved.
Since the and are cut off, the brake fluid discharged from the pump 5 is not consumed. Thereby, the prior art 1 is
Since the load on the pump 5 is reduced, a relatively small pump 5 can be used.

However, in the prior art 1, although the pump 5 can be miniaturized, the valve structure and the circuit structure of the flow path switching valve 9 are complicated, and there is a problem in manufacturing cost. On the other hand, FIG. 7 shows a conventional actuator that allows the flow of brake fluid from the master cylinder side to the wheel cylinder side even during depressurization operation during anti-skid control, thereby simplifying the circuit configuration. Actual Kaihei 6
The device described in Japanese Patent Publication No. -012241 is known (hereinafter, referred to as prior art 2). In this figure, the same components as those shown in FIG. 6 are designated by the same reference numerals and the description thereof will be omitted.

In the prior art 2, a switching control valve 11 is used as a valve for controlling the supply of brake fluid to the wheel cylinder 2.
Is a fluid path 1 between the master cylinder 1 and the wheel cylinder 2.
It is arranged at 0a and 10b. This switching control valve 11 is
It is composed of a first opening / closing valve 12 and a piston 14 having a second opening / closing valve 13 built-in. During depressurization operation during anti-skid control, a master cylinder is provided via a first orifice 12a provided in the first opening / closing valve 12. 1 and the flow of the brake fluid from the discharge side of the pump 5 to the wheel cylinder 2 is allowed, and the brake fluid of the wheel cylinder 2 is supplied from the second orifice 13a provided in the second opening / closing valve 13 and the two-way solenoid valve 6. It is configured to be collected in the reservoir tank 4 via the third orifice 15 provided on the downstream side. The third orifice 15 is provided to set the inflow speed of the brake fluid into the reservoir tank 4. Further, an O-ring 17 is attached to the outer circumference of the piston 14 in order to ensure liquid tightness with the valve housing 16.

As a result, in the prior art 2, the switching control valve 11 has a simple valve structure as compared with the flow path switching valve 9 of the prior art 1, and the circuit configuration is simple.

[0008]

However, the prior art 2 has the following problems. First, when the inflow passage and the outflow passage for the wheel cylinder 2 are schematically shown in FIG. 8 during the depressurization operation during the anti-skid control, the inflow passage for the brake fluid from the master cylinder 1 side to the wheel cylinder 2 is Only one orifice 12a is provided. On the other hand, since the second orifice 13a and the third orifice 15 are provided in series in the outflow passage of the brake fluid from the wheel cylinder 2 to the reservoir tank 4, the partial pressure ratio between the inflow passage and the outflow passage becomes large. The brake fluid pressure is likely to remain in the wheel cylinder 2 even at the final stage of the pressure reducing operation. Therefore, it is difficult to control the pressure increasing / decreasing state of the brake fluid in the wheel cylinder with high accuracy.

Further, since the third orifice 15 on the downstream side of the two-way solenoid valve 6 is provided only for setting the inflow speed of the brake fluid into the reservoir tank 4, there is a problem in terms of manufacturing cost of the control device. There is. Furthermore, the piston 14
Since the O-ring 16 is attached to the outer periphery of the piston, the sliding motion of the piston 14 tends to vary. The present invention has been made in view of the above circumstances, and it is possible to simplify the circuit structure and reduce the manufacturing cost, and reduce the residual pressure of the brake fluid of the wheel cylinder during the pressure reducing operation of the anti-skid control. It is an object of the present invention to provide a brake fluid pressure control device for a possible anti-skid control device.

[0010]

In order to solve the above-mentioned problems, a first aspect of the present invention provides a first supply passage which connects a master cylinder and a wheel cylinder, and a brake fluid discharged from the wheel cylinder. A reservoir tank for storing, a discharge passage that communicates the wheel cylinder and the reservoir tank, a normally-closed electromagnetic on-off valve arranged in the middle of the discharge passage, and a brake fluid stored in the reservoir tank. A master cylinder and a pump that pumps and recirculates pressure to the first supply passage, a second supply passage that branches from the upstream side of the first supply passage to connect the master cylinder and the wheel cylinder, and the second supply passage. A first throttle disposed midway to limit the flow of brake fluid from the master cylinder and the discharge side of the pump to the wheel cylinder; An anti-flow switch that is disposed in the middle of the first supply passage, the second supply passage, and the discharge passage on the wheel cylinder side and controls the supply or discharge of the brake fluid to the wheel cylinder. In the brake fluid pressure control device of the skid control device, the flow passage switching valve includes a shutoff valve that shuts off the first supply passage, and a second shutoff valve.
It is possible to bring the shutoff valve into a communicating state by incorporating a throttle passage having a throttle, and being arranged coaxially with the shutoff valve and moving in the valve housing in a direction to engage with the shutoff valve. A plunger, and during anti-skid control, the flow passage switching valve communicates the second supply passage with the throttle passage, and the brake fluid flows from the discharge side of the pump and the master cylinder to the first throttle and the first throttle passage. The plunger flows out of the shut-off valve due to the pressure difference between the upstream side and the downstream side of the second throttle when the brake fluid passes through the throttle passage while flowing to the wheel cylinder via the second throttle. The structure is characterized in that it moves in the direction of separation.

According to the first aspect of the present invention, when a pressure difference occurs between the upstream side and the downstream side of the second throttle during the anti-skid control, the plunger moves in the direction away from the shutoff valve. Due to this movement of the plunger, the shutoff valve becomes the first
Since the supply passage is shut off, the valve structure and circuit configuration can be simplified as compared with the conventional device. When the anti-skid control depressurizes, the brake fluid discharged from the pump flows toward the wheel cylinder through the first throttle and the second throttle, so that the amount of brake fluid discharged from the pump decreases. As a result, the size of the pump can be reduced.

According to a second aspect of the present invention, in the brake fluid pressure control device for an anti-skid control device according to the first aspect, the flow path is provided when the anti-skid control depressurizes the electromagnetic on-off valve to an open state. The switching valve is characterized in that the discharge passage and the throttle passage are communicated with each other, and the brake fluid flows from the wheel cylinder to the reservoir tank via the first throttle.

According to the invention of claim 2, when the throttle passage and the discharge passage communicate with each other, the inflow speed of the brake fluid flowing from the wheel cylinder to the reservoir tank can be set by the second throttle of the throttle passage. Becomes Thus, unlike the conventional device, the device structure does not require a dedicated throttling means for setting the inflow speed of the brake fluid, so that the manufacturing cost of the control device is reduced. Further, in the present invention, the throttle passage communicates with both the second supply passage and the discharge passage, whereby the brake fluid inflow passage between the master cylinder side and the wheel cylinder is provided with the second supply passage. The first diaphragm provided and the second diaphragm provided in the diaphragm passage are provided in series. Further, only the second throttle is provided in the brake fluid outflow passage that connects the wheel cylinder and the reservoir tank. As a result, the partial pressure ratio between the inflow passage and the outflow passage becomes small, and the brake fluid is unlikely to remain in the wheel cylinder at the final stage of the pressure reducing operation. Therefore, it becomes possible to control the pressure increasing / decreasing state of the brake fluid in the wheel cylinder with high accuracy, and the performance of the anti-skid control is improved.

On the other hand, the invention according to claim 3 is the brake fluid pressure control device for an anti-skid control device according to claim 1 or 2, wherein the plunger is not provided with a seal member such as an O-ring on its outer periphery. And sliding in the valve housing. According to the third aspect of the present invention, the plunger that slides in the valve housing does not have a seal member such as an O-ring on the outer periphery thereof, so that the sliding operation does not vary. Here, if the seal member is not provided on the outer periphery of the plunger, the problem of fluid leakage between the plunger and the valve housing occurs, but in the present invention, the second throttle is provided in the throttle passage. The problem can be solved by selecting the opening of the second throttle in consideration of the leak. Therefore, according to the present invention, the sliding movement of the plunger becomes smooth, and since the sealing member is not required, the manufacturing cost of the control device is further reduced.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 1 shows the overall configuration of the anti-skid control device. In the figure, reference numeral 16 indicates a disc brake device mounted on the vehicle, reference numeral 23 indicates an anti-skid control device for front wheel independent rear wheel collective control for the disc brake device 16, and reference numeral 18 indicates a battery mounted on the vehicle. . The disc brake device 23 is
A master cylinder 20 that outputs brake fluid pressure (braking fluid pressure) in response to depression of the brake pedal 19, and front left to rear right wheels 21FL to 21R by input of brake fluid pressure.
Wheel cylinders 22FL to 22RR for controlling the rotation of R
The anti-skid control device 23 is provided with a wheel speed sensor 24FL to 24RR that detects the rotation state of the wheel, and a controller that commands anti-skid control during braking based on the detection values from these wheel speed sensors 24FL to 24RR. 26,
An actuator (fluid pressure control device) 28FL for individually adjusting the hydraulic pressures of the wheel cylinders 22FL and 22FR on both sides of the front wheel and the hydraulic pressures of the wheel cylinders 22RL and 22RR on both sides of the rear wheel collectively by a control signal output from the controller 26. , 28FR, 28R and the actuators 28FL, 28FL, 28R, and the supply voltage from the battery 14 according to a control signal from the controller 26 during the operation of the anti-skid control.
Actuator relay 29 for supplying to 28FR and 28R
And The wheel cylinder 22 of the present embodiment
FL to 22RR indicate cylinders that press the brake pads against the discs.

The wheel speed sensors 24FL to 24RR are electromagnetic pickups provided at predetermined positions of the wheels 21FL to 21RR, and each output a sine wave AC voltage signal having a frequency proportional to the rotation speed of each wheel. Further, the actuator relay 29 is turned on by the control signal S _AR from the controller 26, and the actuator 28FL, 2
The supply voltage from the battery 18 is supplied to the 8FR and 28R by the control signal from the controller 26, and the drive signals S _AV and S
Supply as _MR .

2 shows the actuator 28F.
Although it is a control circuit diagram showing each of L, 28FR, and 28R, an actuator 28FL for controlling the wheel cylinder 22FL will be described here. This control circuit includes first brake fluid passages 30 and 31 that communicate the master cylinder 20 and the wheel cylinder 22FL (hereinafter, referred to as), a reservoir tank 34 that stores the brake fluid discharged from the wheel cylinder 22FL, and the wheel cylinder 22FL.
And the drainage passages 31, 36 for communicating the reservoir tank 34 with
a, 36b, a normally-closed electromagnetic on-off valve 38 connected between the discharge liquid passages 36a, 36b, and a fluid for pumping and circulating the brake fluid stored in the reservoir tank 34 to the master cylinder 20 and the first brake fluid passage 30. Pressure pump (pump) 40
And second brake fluid passages 42 and 31 that branch from the upstream side of the first brake fluid passage 30 to communicate the master cylinder 20 and the wheel cylinder 22FL, and the master cylinder 20 disposed in the second brake fluid passage 42. And a first orifice (first throttle) 44 that restricts the flow of the brake fluid from the discharge side of the hydraulic pump 40 to the wheel cylinder 22FL, and the fluid passage 31, the first brake fluid passage 30, and the discharge fluid passage 36a. It is an apparatus provided with the flow-path switching valve 32 connected between them.
Here, the first brake fluid passages 30 and 31 correspond to the first supply passage of the present invention, the discharge fluid passages 31, 36a and 36b correspond to the discharge passages of the present invention, and the second brake fluid passage 4 is further provided.
2, 31 correspond to the second supply passage of the present invention.

The suction side and the discharge side of the hydraulic pump 40 are provided with check valves 46a and 46b which allow only the flow of the brake fluid to the master cylinder 20 side. The flow path switching valve 32 includes a shutoff valve 50 and a plunger 54 that is provided coaxially with the shutoff valve 50 and slides axially in a plunger chamber (valve housing) 54a.

That is, the shutoff valve 50 utilizes the movement of the ball 50a arranged in the fluid chamber 50a, and the input port 50b connected to the first brake fluid passage 30.
Is formed, and an output liquid passage 50c that communicates between the fluid chamber 50a and the plunger chamber 54a is formed, and
A return spring 50e for urging the ball 50a in the direction of closing the output liquid passage 50c is disposed in the fluid chamber 50a.

Further, the fluid chamber 50 is connected via the output liquid passage 50c.
In the plunger chamber 54a communicating with a, the output liquid passage 50c
Is formed with a first port 54c connected to the liquid passage 31 on the side of one end face 54b that opens, and a second port 54d connected to the discharged liquid passage 36a on the side of the other end face 54e. Then, one end surface 54 is provided in the plunger chamber 54a.
Plunger 54 that slides on the b side and the other end surface 54e side
Is integrally provided with an actuator 54e that extends toward the fluid chamber 50a through the communication passage 50c, and the plunger 54 is urged toward the one end surface 54b. A spring 54f is provided. Here, the plunger chamber 54a, the upper oil chamber from the plunger 54 to one end face 54b side (first fluid chamber) 54a ₁ are provided, the lower oil chamber to the other end face 54c side (second fluid chamber) 54a ₂ is Although provided, the first fluid chamber 54a ₁ and the second fluid chamber 54a ₂ communicate with each other through a throttle channel (throttle passage) 54g formed in the plunger 54. And, in the throttle channel 54g,
A second orifice (second diaphragm) 52 having a predetermined opening area is provided.

As shown in FIG. 2, the electromagnetic on-off valve 38 is a spring offset type two-port, two-position electromagnetic switching valve, in which a spool 38b is disposed in the fluid chamber 38a and the switching control valve 32 side is provided. An input port 38c connected to the discharge liquid passage 36a and the discharge liquid passage 36 on the reservoir tank 36 side
An output port 38d connected to b is formed, and a return spring 38e for urging the spool 38b is arranged at a position to close the space between the input port 38c and the output port 38d, and a drive signal from the controller 26. A solenoid 38f for moving the spool 38a by the on / off control of S _AV is provided.

Then, the drive signal S to the solenoid 38f
_{When the AV} is turned off, the spool 38b is urged by the return spring 38e and the input port 38c and the output port 38
It is in a closed state where it disconnects from d. In addition, solenoid 3
When the drive signal S _AV to 8f is turned on, the drive signal S _AV
Return spring 3 while _EV remains on
The spool 38b moves against the urging force of 8e, and the input port 38c and the output port 38d communicate with each other to be in an open state.

Then, the above-described controller 26 turns off the drive signal S _AV to the solenoid 38f of the electromagnetic opening / closing valve 38 during normal brake operation (when anti-skid is not controlled). Further, during the anti-skid control, the pseudo vehicle speed is calculated from the wheel speed detection value according to a predetermined program based on the wheel side detection value obtained from the wheel speed sensors 24FL to 24RR, and the calculated pseudo vehicle speed and the wheel speed detection value are predetermined. The respective wheel speeds within the slip ratio range are calculated, and the solenoid 38f of the electromagnetic opening / closing valve 38 is adjusted so as to achieve the wheel speed.
On / off control of the drive signal S _AV is performed with respect to. Also,
For the hydraulic pump 40, the controller 26 turns off the drive signal S _MR during normal braking and turns on the drive signal S _MR during anti-skid control.

Next, the operation of the above embodiment during normal brake operation and anti-skid control will be described with reference to FIGS.
This will be described with reference to FIG. First, at the time of normal boom operation, the drive signal S _AV to the solenoid 38f of the electromagnetic on-off valve 38 is turned off to close the electromagnetic on-off valve 38. At this time, the second
Since the pressure difference is not generated between a hydraulic P ₁ of the hydraulic P ₂ and the first fluid chamber 54a ₁ of the fluid chamber 54a ₂ (P ₁ = P _2), 2
As shown in FIG.
4e is urged to move to the one end face 54b side, and the actuator 54e of the plunger 54 moves the ball 50 of the shutoff valve 50.
d is pressed and moved in a direction against the biasing force of the return spring 50e. By this operation, the shutoff valve 50 is brought into an open state in which the input port 50a and the output liquid passage 50c communicate with each other.

When the brake pedal 16 is depressed, the brake fluid having a predetermined pressure generated by the master cylinder 18 is supplied to the first brake fluid passage 30 and the input port 5.
0b, fluid chamber 50a, output liquid passage 50c, first fluid chamber 53
a ₁ is supplied to the wheel cylinder 22FL via the liquid passage 31. Further, when the depression operation of the brake pedal 16 is released, the shutoff valve 50 is held in the open state.
Contrary to the flow of the brake fluid in the depression operation described above, the fluid passage 31, the first fluid chamber 54a ₁ , the output fluid passage 50c, the fluid chamber 5
The brake fluid flows into the master cylinder 18 via the 0a, the input port 50b, and the first fluid passage 30a, and the entire pressure inside the wheel cylinder 22FL is reduced.

On the other hand, when the front left to rear right wheels 21FL to 21RR are about to lock in the brake operating state, a drive signal to the hydraulic pump 40 is generated based on the wheel side detection values obtained from the wheel speed sensors 24FL to 24RR. When S _MR is turned on, anti-skid control is performed to perform on / off control of the drive signal S _AV for the solenoid 38f of the solenoid opening / closing valve 38.

During the pressure reducing operation of the anti-skid control, the drive signal S _AV to the solenoid 38f of the electromagnetic opening / closing valve 38 is turned on to open the electromagnetic opening / closing valve 38. At this time, the brake fluid in the wheel cylinder 22FL is discharged through the fluid passage 3
1, the first fluid chamber 54a ₁ , the throttle channel 54g, the second orifice 52, the second fluid chamber 54a ₂ , the discharge liquid passage 36a, the electromagnetic opening / closing valve 38, and the discharge liquid passage 36b, and the reservoir tank 3
Collected in 4.

Then, through the second orifice 52, the first
By the brake fluid in the fluid chamber 54a ₁ flows into the second fluid chamber 54a _2, the upstream side and the pressure difference is generated in the downstream side, the first hydraulic pressure P ₁ of the fluid chamber 54a ₁ of the second orifice 52 second
It becomes larger than the hydraulic pressure P _{2 in the} fluid chamber 54a ₂ (P ₁ >).
P ₂ ). The hydraulic pressure P _{1 of} the first fluid chamber 54a ₁ acts on the plunger 54 as a force that opposes the biasing force of the return spring 54f, so that the plunger 54 has the other end surface 5
4c side, and along with that, the actuator 54e also moves to the other end face 54c side. As a result, as shown in FIG. 3, the ball 50d is urged by the return spring 50e to close the output liquid passage 50, and the shutoff valve 50 is closed. As a result, the brake fluid pressure of the wheel cylinder 22FL starts to drop.

When the anti-skid control shifts to the pressure increasing operation after the pressure reducing operation, the drive signal S _AV to the solenoid 38f of the electromagnetic opening / closing valve 38 is turned off and the electromagnetic opening / closing valve 38 is closed. At this time, due to the closed state of the electromagnetic opening / closing valve 38, the flow of the brake fluid from the first fluid chamber 54a ₁ to the second fluid chamber 54a ₂ does not occur, and the pressure difference between the upstream side and the downstream side of the second orifice 52 disappears. Therefore, the force against the biasing force of the return spring 54f is lost, and the plunger 5
4 moves to the one end face 54b side. However, the return spring 54f does not generate an urging force against the hydraulic pressure P ₁ generated in the first fluid chamber 54a ₁ , so that the plunger 5
4 does not contact the ball d of the shutoff valve 50,
The shutoff valve 50 maintains the closed state.

The brake fluid in the master cylinder 18 is the first brake fluid passage 30, the discharge fluid passage 42, the first orifice 44, the second fluid chamber 54a ₂ , the throttle passage 54g, and the second fluid passage 54g.
It is supplied to the wheel cylinder 22FL through the orifice 52, the first fluid chamber 54a ₁ and the liquid passage 31. At this time, the brake fluid is supplied to the first orifice 44 and the second orifice 52 while being throttled, so that the brake fluid pressure of the wheel cylinder 22FL gradually increases,
Slow boosting effect can be obtained.

When the pressure increasing operation is continued, the brake fluid in the second fluid chamber 54a ₂ flows into the first fluid chamber 54a ₁ via the second orifice 52, so that the upstream side and the downstream side of the second orifice 52 are A differential pressure is generated in the second fluid chamber 5
Fluid pressure P ₂ of 4a ₂ is compared to the fluid pressure P ₁ of the first fluid chamber 54a ₁ atmospheric next (P _2> P _1), the fluid pressure P ₂ of the second fluid chamber 54a ₂ is a plunger 54 either It works as a force to move the end face 54b side. However, the sum of this force and the urging force of the return spring 54f is the first fluid chamber 54a ₁
Since it is not possible to overcome the hydraulic pressure P ₁ of ₁ , the operator 54e of the plunger 54 does not contact the ball d of the shutoff valve 50, and the shutoff valve 50 maintains the closed state. As a result, the brake fluid is supplied to the first orifice 44 and the second orifice 52 in a squeezed state, and the slow pressure increasing effect is continued.

By the way, during the depressurizing operation of the anti-skid control, as shown in the figure, the master cylinder 20 is connected to the first brake fluid passage 30, the discharge fluid passage 42, and the first orifice 4.
4, the third fluid passage 36a, the second fluid chamber 54a _2, the communication passage 54
g, the second orifice 52, the second fluid chamber 54a ₁ and the second
The flow of the brake fluid to the wheel cylinder 22FL via the fluid passage 30b is allowed. The inflow passage of the brake fluid has the first orifice 44 and the second orifice 52 arranged in series, while the outflow passage of the brake fluid from the wheel cylinder 22FL to the reservoir tank 34 has only the second orifice 52. Is provided, the circuit is configured to reduce the partial pressure ratio of the inflow passage and the outflow passage of the brake fluid, and the residual pressure remains in the wheel cylinder 22FL during the pressure reducing operation of the antiskid control as compared with the conventional device. Hateful.

That is, the anti-skid system of this embodiment
Figure 5 shows the inflow and outflow paths during decompression operation.
The conventional apparatus shown in FIG.
This will be described in comparison with the circuit configuration of Japanese Patent No. 12241). This
Here, P is the residual pressure of the foil._H, From the master cylinder side
Liquid pressure to master pressure P _M, Reserve the fluid pressure on the reservoir tank side.
Pressure P_TAnd

In the circuit of the conventional apparatus shown in FIG. 8, the first orifice 12a is provided in the inflow passage, and the second orifice 13a and the third orifice 15 are provided in series in the outflow passage. In this circuit, the residual pressure of the foil is set to the first orifice 12a, the second orifice 13a, and the third orifice 1 with the outflow passage and the reservoir tank 4 communicating with each other.
Approximating the final balance pressure by the differential pressure of 5, the wheel residual pressure P _H = reservoir pressure P _T + master pressure P _M × (differential pressure of second orifice + differential pressure of third orifice) / (first orifice) Differential pressure) ... (1).

On the other hand, in the circuit of this embodiment shown in FIG. 5, the first orifice and the second orifice 52 are provided in series in the inflow passage, and only the second orifice 52 is provided in the outflow passage. In this circuit, as a state in which communication between the outlet passage and the reservoir tank 34 and to approximate the foil residual pressure as finally balanced pressure due to the pressure difference of the first orifice 44 and second orifice 52, the foil residual pressure P _H = reservoir Pressure P _T + master pressure P _M × (differential pressure of second orifice) / (differential pressure of first orifice + differential pressure of second orifice) (2)

Here, the differential pressure of the second orifice of the formula (2) corresponds to the sum of the differential pressure of the second orifice and the differential pressure of the third orifice of the formula (1). As is clear from the above formulas (1) and (2), in the present embodiment, only the second orifice 52 is provided in the discharge passage, and therefore, in the final stage of the depressurization operation as compared with the conventional device. Is the wheel cylinder 22
Residual pressure hardly remains in FL. Therefore, since it is possible to control the pressure increase / decrease state of the brake fluid in the wheel cylinder 22FL with high accuracy, the performance of the anti-skid control is improved.

Further, in this embodiment, during the anti-skid control, the plunger 54 moves due to the pressure difference between the pressure on the upstream side and the pressure on the downstream side of the second orifice 52, and the plunger 54 moves to shut off. Since the closing operation of the valve 50 is performed and the switching control of the brake fluid is performed at the same time, the valve structure and the circuit configuration can be simplified as compared with the conventional device. At the same time, during depressurization operation of the anti-skid control, the brake fluid discharged from the hydraulic pump flows to the wheel cylinder 22FL side through the second brake fluid passage 42, and the first orifice 42 of the second brake fluid passage 42 causes the brake fluid to flow. Since the flow of the brake fluid is limited, the amount of brake fluid discharged from the hydraulic pump 40 is reduced. As a result, the hydraulic pump 40 can be downsized.

The inflow speed of the brake fluid flowing from the wheel cylinder 22FL to the reservoir tank 34 is the second
Since it can be set by the orifice 52, it is possible to reduce the manufacturing cost of the control device without requiring a dedicated throttling means for setting the inflow velocity of the brake fluid unlike the conventional device. Further, since the plunger 54 sliding in the plunger chamber 54a is not provided with a seal member such as an O-ring on its outer circumference, the sliding operation does not vary. Here, by not disposing the seal member on the outer periphery of the plunger 54, a problem of brake fluid leak between the plunger 54 and the plunger chamber 54a occurs,
In the present embodiment, the problem can be solved by selecting the throttle opening degree of the second orifice 52 in consideration of the leak as well. As a result, by not using a seal member such as an O-ring, the sliding movement of the plunger 54 can be made smooth, and the manufacturing cost of the control device can be further reduced.

In the present embodiment, the case where the disc type brake is applied is shown, but this can be similarly applied to the drum type brake. At that time, the wheel cylinders 22FL to 22RR are cylinders that press the brake shoes against the drum. Further, although the case where the wheel cylinders 22FL to 22RR are hydraulically controlled has been described in the present embodiment, it is needless to say that the present invention is not limited to this and other liquids or gases such as air can be applied.

[0040]

As described above, according to the first aspect of the present invention, when a pressure difference occurs between the upstream side and the downstream side of the second throttle during the anti-skid control, the plunger moves in the direction away from the shutoff valve. I will do it. Since the shutoff valve shuts off the first supply passage by the movement of the plunger, the valve structure and the circuit configuration can be simplified as compared with the conventional device. And when decompressing the anti-skid control,
Since the brake fluid discharged from the pump flows toward the wheel cylinder through the first throttle and the second throttle, the amount of brake fluid discharged from the pump is reduced. Accordingly, the present invention can reduce the size of the pump.

The invention of claim 2 can obtain the effect of claim 1, and when the throttle passage and the discharge passage communicate with each other, the inflow speed of the brake fluid flowing from the wheel cylinder to the reservoir tank is reduced. It can be set by the second throttle of the passage. Therefore, unlike the conventional device, the device structure does not require a dedicated throttling means for setting the inflow speed of the brake fluid, so that the manufacturing cost of the control device can be reduced.

Further, in the present invention, the throttle passage communicates with both the second supply passage and the discharge passage, whereby
A first throttle provided in the second supply passage and a second throttle provided in the throttle passage are provided in series in the brake fluid inflow passage between the master cylinder side and the wheel cylinder. . Further, only the second throttle is provided in the brake fluid outflow passage that connects the wheel cylinder and the reservoir tank. As a result, the partial pressure ratio between the inflow passage and the outflow passage becomes small, and the brake fluid is unlikely to remain in the wheel cylinder at the final stage of the pressure reducing operation. Therefore, it is possible to control the pressure increase / decrease state of the brake fluid in the wheel cylinder with high accuracy, and it is possible to improve the performance of the anti-skid control.

Further, the invention of claim 3 can obtain the effect of claim 1 or 2, and the plunger sliding in the valve housing has a seal member such as an O-ring arranged on the outer periphery thereof. Therefore, there is no variation in the sliding operation. Here, if the seal member is not provided on the outer periphery of the plunger, a problem of fluid leakage between the plunger and the valve housing occurs, but in the present invention, the second passage is provided in the throttle passage. The problem can be solved by selecting the opening of the throttle in consideration of the leak. Therefore, the present invention makes the sliding movement of the plunger smooth and does not require a seal member,
Further, the manufacturing cost of the control device is reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an anti-skid control device of the present invention.

FIG. 2 is a circuit diagram showing a normal brake operation of the fluid pressure control device of the anti-skid control device of the present invention.

FIG. 3 is a circuit diagram showing a pressure reduction operation of anti-skid control of the fluid pressure control device of the present invention.

FIG. 4 is a circuit diagram showing a pressure increasing operation of anti-skid control of the fluid pressure control device of the present invention.

FIG. 5 is a schematic diagram showing a circuit in which the master cylinder side and the wheel cylinder side are communicated with each other via a throttle during the pressure increase operation of the anti-skid control in the fluid pressure control device of the present invention.

FIG. 6 is a first example showing a circuit configuration of a conventional fluid pressure control device.

FIG. 7 is a second example showing a circuit configuration of a conventional fluid pressure control device.

FIG. 8 is a schematic diagram showing a circuit in which a master cylinder side and a wheel cylinder side are communicated with each other through a throttle in a pressure increasing operation of anti-skid control in a second example of the conventional device.

[Description of Reference Signs] 20 master cylinder 22FL to 22RR wheel cylinder 28FL, 28FR, 28R actuator (fluid pressure control device) 30, 31 first brake fluid passage (first supply passage) 31, 36a, 36b exhaust fluid passage (exhaust passage) ) 32 flow path switching valve 34 reservoir tank 38 electromagnetic opening / closing valve 40 hydraulic pump (pump) 42, 31 second brake fluid passage (second supply passage) 44 first orifice (first throttle) 50 shutoff valve 52 2 Orifice (second throttle) 54 Plunger 54a Plunger chamber (valve housing) 54g Throttle flow path (throttle passage)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Motoko Kosaka, 2 Takaracho, Kanagawa-ku, Kanagawa, Nissan Nissan Motor Co., Ltd. 72) Inventor Hideaki Inoue 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd.

Claims (3)

[Claims] 1. A first supply passage that connects the master cylinder and the wheel cylinder, a reservoir tank that stores the brake fluid discharged from the wheel cylinder, and a discharge passage that connects the wheel cylinder and the reservoir tank. A normally closed electromagnetic on-off valve disposed in the middle of the discharge passage, a pump for pumping and circulating the brake fluid stored in the reservoir tank to the master cylinder and the first supply passage, and the first supply passage A second supply passage branched from the upstream side of the master cylinder and the wheel cylinder to communicate with each other, and a second supply passage disposed in the middle of the second supply passage from the discharge side of the master cylinder and the pump to the wheel cylinder. A first throttle for restricting the flow of brake fluid, and the foil cylinder of the first supply passage, the second supply passage and the discharge passage. In a brake fluid pressure control device of an anti-skid control device, which includes a flow passage switching valve that is arranged midway on the da side and that controls the supply or discharge of brake fluid to the wheel cylinder, A shut-off valve that shuts off the first supply passage, and a throttle passage having a second throttle, and is arranged coaxially with the shut-off valve and moves in a valve housing in a direction to engage the shut-off valve. And a plunger capable of bringing the shut-off valve into a communication state, and, during anti-skid control, the flow path switching valve includes the second
The supply passage and the throttle passage are communicated with each other, and the brake fluid flows from the discharge side of the pump and the master cylinder to the wheel cylinder through the first throttle and the second throttle, and the brake fluid is supplied to the throttle passage. The brake of the anti-skid control device having a structure in which the plunger moves in a direction away from the shut-off valve due to a pressure difference between the upstream side and the downstream side of the second throttle when passing through the second throttle. Fluid pressure control device. 2. The flow passage switching valve connects the discharge passage and the throttle passage at the time of depressurizing operation of anti-skid control in which the electromagnetic opening / closing valve is opened, and brake fluid flows from the wheel cylinder to the first passage. The brake fluid pressure control device for an anti-skid control device according to claim 1, wherein the brake fluid pressure control device is configured to flow to the reservoir tank through the throttle 1. 3. The brake for an anti-skid control device according to claim 1, wherein the plunger slides in the valve housing without disposing a seal member such as an O-ring on the outer periphery of the plunger. Fluid pressure control device.