JPS62131853A - Dual system type anti-skid brake hydraulic pressure control device - Google Patents

Abstract

PURPOSE:To enhance the safety of an antiskid brake hydraulic control device, by supplying pressure from a normal system pressure to rear wheel brake devices when one of two systems falls into an abnormal condition. CONSTITUTION:When an antiskid function is effected, discriminating devices 9a, 9b discriminate the prevention of antiskid at right and left front wheels, independently, and therefore, a pressure differential occurs between front wheel brake devices 5a, 5b. At this time a selector valve 10 selects a lower pressure which is fed to rear wheel brake devices 7a, 7b through a hydraulic pressure control valve 6. Further, when one of pressure chambers 3a, 3b in a master cylinder 3 fails, the function of the selector valve 10 is negated, and therefore, brake is effected by one of the front wheels and one of the rear wheels.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a two-system anti-skid brake fluid pressure control device used in vehicles and the like.

(Prior art) The behavior of the front two wheels of the four wheels of a car, etc., that is, the wheel speed, is independently monitored, and the system monitors the behavior of each wheel independently to determine if skid has occurred or is about to occur in the front two wheels. In this case, the brake fluid pressure supplied to each of the two wheels is adjusted independently, thereby preventing the front two wheels from skidding or skidding tendency, while the brake fluid pressure supplied to the two rear wheels is adjusted independently. Pressure is supplied via a hydraulic pressure control valve that reduces the pressure at a predetermined pressure reduction ratio above a predetermined pressure.

This not only prevents the front two wheels from skidding, but also reduces the pressure obtained as a result of the control.

Since hydraulic pressure can be supplied to the rear two wheels through a hydraulic pressure control valve with a certain degree of control based on the relationship based on the predetermined brake force distribution of the vehicle, it is expected that skids on the rear two wheels will also be prevented. be done.

However, in this type of vehicle, the pressure in the front two wheels is controlled independently, which is preferable, but for the two rear wheels, the pressure supplied to the left and right axes differs greatly, and the left and right wheels are controlled independently. This causes a problem in that the brake balance on the shaft deteriorates, making it inconvenient to prevent the vehicle from rolling sideways.

Therefore, the lower of the two hydraulic pressures obtained as a result of the control of the front two wheels is supplied to the rear two wheels.
It was proposed to ensure braking stability of the rear two wheels.

As a concrete means.

Hydraulic pressure is supplied to the left and right front wheel brake devices in response to commands from a discrimination circuit that monitors wheel behavior, to two piping systems that independently supply hydraulic pressure from the two-system mask cylinder to the left and right front wheel brake devices. A hydraulic pressure regulating device capable of regulating the pressure is provided respectively, and the pressure regulated by the hydraulic pressure regulating device is supplied to the left and right rear wheel brake devices respectively, and the pressure regulated by the hydraulic pressure regulating device is supplied to the left and right rear wheel brake devices. Provide a selection valve,
This selection valve consists of a piston that receives the pressure in two pipings facing each other at both ends and is movable from a neutral position to each end side due to the differential pressure, and a piston that is provided facing each side of the piston. a pair of valve devices that close when the hydraulic pressure adjusting device is in the neutral position and the approaching position and close when the hydraulic pressure adjusting device moves away from the neutral position, and control communication and disconnection between the hydraulic pressure adjusting device and the rear wheel brake device. was proposed.

(Problem to be Solved by the Invention) According to this proposal, during normal control, the pressure to the rear two wheels is the lower of the two hydraulic pressures obtained as a result of control to the front two wheels. This has the advantage that the hydraulic pressure is lower than that of the previous one. However, on the other hand, if a malfunction occurs in which pressure is not generated in one of the supply piping systems to the front two wheels, the selection valve selects the pressure of this malfunctioning system as the low pressure. Although one belongs to the normal system, a problem arises in that pressure is no longer supplied.

This problem means that if one system fails, the entire braking force has to be borne only by the front wheel, which is a huge problem, as braking distance increases significantly and accidents occur as a result. There is a risk that it will develop into

In this invention, even if the selection valve as described above is provided, if one of the two systems fails and there is no abnormal pressure drop or pressure generation, normal control is sent to the rear wheels belonging to the normal system. The purpose is to be able to supply pressure.

(Means for solving the problem) In this invention, the pressure of the piping system to which it belongs is received by a small pressure receiving surface at one end, and the pressure of the piping system to which it does not belong is received by the large pressure receiving surface at the other end. A movable body is provided, and each of the pair of valve devices in the selection valve is adjusted according to the movement of the movable body,
Even when the piston moves, communication with the rear wheel brake device through the associated piping system is not interrupted.

Note that the piping to which this invention is applied is generally
A method called the J piping system is suitable.

(Operation) According to the means of the present invention, a movable body that receives the pressure of two piping systems facing each other has a pressure-receiving area when the system to which one of the valve devices belongs is normal and the system to which it does not belong is abnormal. Even if there is a difference, the valve devices will move even if there is a difference, and the valve device belonging to the normal system will not close, so pressure can be supplied to the rear wheel brake device on the normal system side.

(Embodiment) FIG. 1 is a diagram showing a two-system anti-skid brake fluid pressure control device according to an embodiment of the present invention, and FIG. 2 is an enlarged view of a selection valve.

In FIG. 1, the entire brake system including a two-system anti-skid brake hydraulic pressure control device is designated by the symbol l. The brake system 1 includes a two-system tandem master cylinder 3 operated by a brake pedal 2 operated by a driver. One pressure chamber 3a of the master cylinder 3 is connected to the brake device 5a of the right front wheel and the first port 11a of the selection valve 10 through one adjustment part 4a of the hydraulic pressure adjustment device 4 by piping, and is connected to the first port 11a of the selection valve 10 by another piping. It is directly connected to the first control port 12a+ of the selection valve 10. Then, in the selection valve 10, the first population 11a
The first outlet 13a is connected to the left rear wheel brake system [7a] via one adjustment section 6a of the two-system hydraulic pressure control valve 6 via piping. are doing.

Further, the other pressure chamber 3b of the mask cylinder 3 is connected to the left front wheel brake system [! 5b and the second inlet 111) of the selection valve 10, and directly to the second control port 121) of the selection valve 10 by another piping. And selection valve 10
In this case, the second outlet 11b is connected to the second outlet 131), and this second outlet 13b is connected to the right rear wheel via the other adjustment part 6b of the two-system hydraulic pressure control valve 6. It communicates with the brake device 7b. The piping system shown in FIG. 1 is called the X piping system.

The hydraulic pressure adjustment device 14 includes a discrimination circuit 9a that receives input from wheel speed sensors 8a and 8b provided for each front wheel.
, 9b. The device 4 itself is
This is of a conventionally known type, and for example, in response to commands from the first discrimination circuits 9a and 9b, the brake fluid pressure supplied to the front wheel brake devices 5a and 5b is relaxed to a low pressure, or to a constant pressure. The pressure is maintained at a constant temperature and the pressure is increased. In addition, the first discrimination circuits 9a and 9b monitor the behavior of the wheels when the brakes are applied, for example, changes in wheel speed, and compare this with a reference value, etc., and detect whether the wheels skid or have a tendency to skid. By doing so, a command to change the brake pressure is given to the hydraulic pressure adjusting device 4, thereby preventing the wheels from skidding.

The two-system hydraulic pressure control valve 6 includes brake devices 7a and 7 for each rear wheel.
1) is reduced at a predetermined ratio when it exceeds a predetermined pressure, and performs hydraulic pressure control that is set according to the front and rear wheel brake distribution relationship. Note that the two-system hydraulic pressure control valve 6, the aforementioned hydraulic pressure adjustment device t4, and the discrimination circuits 9a and 9b are well known in the art, so detailed explanations thereof will be omitted.

The selection valve 10, as shown in FIG.
5a and 15b. Left lid member 15
a is a stepped sleeve 2 between the large diameter hole 16 on the left side of the through hole 14 and the step 14a between the medium diameter hole 17 in the center.
Sleeve 20 with 0 step that also has the function of fixing 0
are tightly fitted into the large-diameter hole 16 and the medium-diameter hole 17, respectively. This stepped sleeve 20 has a stepped through hole 2.
The diameter of the 0 through hole 20a in which 0a is located is larger on the side of the lid member 15a, and the stepped piston 21a is movably inserted from the larger diameter portion to the middle diameter portion on the right side. has a flange 23a with a notch 22a on the left end side. The flange 23a is the sleeve 20
It can come into contact with the left end of. On the other hand, the stepped piston 21a
There is a protrusion 24 , a on the right side of the protrusion 24 ta .
A cylindrical member 25a is caulked to x. A valve spring 26a is housed inside the cylindrical member 25a, and the valve spring 26a urges the valve body 29a to the right. The valve body 29a has the left end surface of the inward flange portion defining the right side opening 27a of the sleeve 20 as the valve seat 28a, and
The left end flange portion 30a and the reduced diameter portion 31a of the cylindrical member 25a
and can come into contact with each other. Note that a cavity 32a formed in the stepped portion of the single-stage piston 21a communicates with a drain cavity 33a through a hole in the sleeve 20 and a hole in the main body 15, and communicates with the outside air through a check valve 34a.

A second control chamber 35b is formed between the left end side of the sleeve 20 and the stepped piston 21a and the lid member 15a. This control chamber 351) communicates with the second control port 12b. On the other hand, the right end side of the stepped piston 21a and the sleeve 2
A first person's room 37a is formed between the right inner end of 0 and the right inner end. This first control chamber 37a communicates with the first population 11a through a hole in the sleeve 20. As a result, the stepped piston 21a has a relatively small pressure receiving area on the right end side.
The pressure in the passenger compartment 37a is received, and the pressure in the second control chamber 35b is received with a relatively large pressure receiving area on the left end side.

Further, the portion from the right end of the sleeve 20 to the step portion 14b between the smallest diameter opening 27b of the through hole 14 and the medium diameter hole portion 17 is a portion of the medium diameter hole 17 having the same diameter. A piston 38 is movably inserted therein. The piston 38 has a first outlet chamber 39 a and a second outlet chamber 39 on both sides.
b, respectively, and receive pressure from both outlet chambers 39a and 39b with equal pressure receiving areas. The piston 38 has shaft parts 38a and 38b on the left and right, each shaft part 38a
, 38b are movably fitted into the openings 27aa, 27b, respectively. One shaft portion 38a comes into contact with the aforementioned valve body 29a to enable the valve body 29a to be removed from the valve seat 28a. Furthermore, a spring receiver 40 is held on the outer periphery of the piston 38, and a spring 40a is stretched between the spring receiver 40 and the piston 38.

The spring 40a is in elastic contact with the sleeve 20 via the spring receiver 40. Also, around the other shaft portion 38b, a stepped portion 1
A spring 40b is stretched between the piston 38 and the piston 38. As a result, the piston 38 is normally in the neutral position,
In other words, the stepped portion 14b and the sleeve 20 are located at the same distance of movement. The first outlet chamber 39a on the left side of the piston 38 is connected to a groove 20b formed at the end of the sleeve 20.
, the opening 27a, and between the valve seat 28a and the valve body 29,a to communicate with the first person chamber 37a.
It communicates with the exit 13a. The center portion of the outer periphery of the piston 38 communicates with the drain space 41 and is connected to the drain check valve 4.
It communicates with the outside air through 2.

On the other hand, the stepped hole 18 portion on the right end side of the through hole 14 is formed symmetrically with the through hole 20a of the sleeve 200 and has the same inner diameter.

A stepped piston 21b having the same shape as the stepped piston 21a is movably inserted therein, and a space between the right end of the zero-stage piston 21t) and the lid member 15b communicates with the first control port 12a. There is a first control room 35a.

Further, the cavity 32b in the central stage of the single-stage piston 21b communicates with the outside air through the drain cavity 33b and the check valve 34b, and furthermore, between the left end side and the stage 14b, a second passenger compartment 37b is provided. There is. The second person's room 37r1) communicates with the second person's room 11-b and communicates with the second person's room 37r1) through the opening 27b.
It communicates with the exit chamber 39b. Furthermore, a flange 23b with a notch 22b is provided at the right end of the stepped piston 21b.
There is. The flange 23b is connected to the stepped portion 18t of the stepped hole 18.
). Further, a cylindrical member 25b is caulked to the protrusion 24b on the left end side of the stepped piston 21b. A valve spring 26t) and a valve member 29b biased by the valve spring 26b are arranged on the inner periphery of the cylinder member 25b. The valve member 29b is a valve body with the right end peripheral portion of the opening 27b as the valve seat 28b, and the right end flange portion 30
b and the reduced diameter portion 31b of the cylindrical member 25t) can come into contact with each other. This stepped piston 21b also receives the pressure of the second passenger chamber 37b with a relatively small pressure receiving area on the left end side, and receives the pressure of the first control chamber 35a with a relatively large pressure receiving area on the right end side.

In such a selection valve 10, the length in the axial direction is defined as follows.

Ll < L, <<L<L4...(1) L
s + L2> Ls (2) L1 to L indicate the following distances.

L construction: Distance L2 between the piston 38 in the neutral position and the stepped portion 14b and the sleeve 20...Each stepped piston 21a, 21b is in contact with the left end of the sleeve 20 and the stepped portion 18b, and When each shaft portion 38a, 38b of the piston 38 in the neutral position is in contact with each valve body 29a, 29b, each valve body 29
Distance L required for a, 29b and each valve seat 28aa, 28b to be seated, . . . each valve body 29a under the same conditions as L2 above.

291) flanges 30 a, 30 b and cylindrical member 25
The distance L4 required for the valve bodies 29a and 25b to engage with each other under the same conditions as described above.

291) and each protrusion 2 of each stepped piston 21a, 21b
4a, 24b, . . . the distance between each stepped piston 21a, 21b and each lid member 15a, 15b. These relationships will be easily understood from the explanation of the operation described later. In addition, in FIG. 2, Sl indicates a lip-type sealing member, and S2 indicates an O-ring-type sealing member.

Next, the operation of the brake system 1 mentioned above will be explained.

When the brake pedal 2 is depressed, brake fluid pressure is supplied from the mask cylinder 3 to each piping system, but the fluid pressure is supplied to the fluid pressure regulator 4. It is supplied to the front wheel brake devices i5a, 5b through the hydraulic pressure adjusting device 4, the selection valve 10, and the hydraulic pressure control valve 6 to the rear wheel brake devices 1a, 1b. The brakes begin to apply, and the vehicle etc. begins to decelerate.At this time, the pressures generated in the pressure chambers 3a and 3b of the mask cylinder 3 are equal, and the hydraulic pressure adjustment device 4 does not operate, so each of the left and right front wheels The pressure supplied to the brake equipment [5a, 5b is equal, each port 11a, llb of the selection valve 10 and each control port 12a,
12b are also equal and the selection valve 10 is not operated, the pressures at each outlet 13a, 13b of the selection valve 10 are equal, and the hydraulic pressure control valve 6 is supplied to the outlet 13a, 13b.
If the pressure supplied from
convey pressure to.

Thereafter, even if the brake fluid pressure increases, if the anti-skid action is not performed, when the pressure reaches a predetermined pressure, the fluid pressure control valve 6 operates and the brake devices 17a, 71
) is supplied with reduced hydraulic pressure at a predetermined ratio.

- In the case of anti-skid action When the pressure supplied to each brake device 5a, 5b and 7a, 7b reaches a pressure that causes the wheels to skid, the discrimination devices 9e*, 9b reduce the pressure to be supplied. As a result of giving a command to the hydraulic pressure adjustment device 4 as shown in FIG. Each adjustment section 4a of the hydraulic pressure adjustment device 4 functions to independently determine skid prevention.

As a result of the adjustment 4b, a pressure difference is generated between the pressure on the brake equipment side [5a side and the brake equipment 51 side pressure]. This may occur, for example, when the conditions of the road surface on which the left and right front wheels run are different, or when the discrimination device 9 a.

This is caused by operating errors of the respective adjustment sections 4a and 4b based on commands from the controller 91).

When such a pressure difference occurs, the selection valve 10 selects the lower pressure, lowers the higher pressure to the lower pressure, and supplies the lower pressure to the hydraulic pressure control valve 6 side.

Therefore, this low pressure is supplied to each brake device 7ca, 7b of the rear wheels via the hydraulic pressure control valve 6, thereby preventing skids in the rear wheels.

As a result, each brake device 5a, 5b and 7aa,
The pressure supplied to 7b is adjusted to a pressure that does not cause skidding on each wheel.

・　　10　　2 ・When there is no anti-skid effect Each inlet 37a, 37b and each control room 35a.

35b are all at the same pressure, and each stepped piston 2
1a and 21b receive the pressure of the control chambers 35a and 35b in a large pressure receiving area, and are an inlet chamber 37a.

The pressure of 37b is received in a small pressure receiving area. Therefore, each of the stepped pistons 21a and 21b receives a biasing force toward the center and is in a position where it abuts the sleeve 20 and the stepped portion 18b, respectively, and the respective lid members 15a.

151), a distance Ls is secured between the two. Furthermore, the pressures in the outlet chambers 39a, 39b communicating with the respective inlet chambers 37a, 37b are also equal. Therefore, the piston 38.

The biasing force of springs 40a and 40b and each outlet chamber 39a
.

39k) are balanced and at neutral positions, and an equal distance lx is maintained between the sleeve 20 and the stepped portion 14b. At this time, each shaft portion 38a of the piston 38.

38b is in contact with each valve body 29a, 29b, and each valve body 2
9a and 29b are equally spaced from each valve seat 28a and 28b by a distance L2. Accordingly, each valve body 29a
, 29b's flange portion 30a.

30t) and reduced diameter portions 31a of the cylindrical members 25a and 25b.

31b, and a distance L4 between the protrusions 24a and 24b.

This condition continues for as long as the pressure in each inlet chamber 37a, 37b and in each control chamber 35a, 35b is equal, during which time the pressure from the outlet chamber 39a, 39b to the outlet 13a, 13
The pressure supplied to the hydraulic pressure control valve 6 through b maintains the same value without being reduced.

- When there is an anti-skid effect, the pressures supplied to the inlet chambers 37a, 37b will be different due to the independent operation of the hydraulic pressure regulators 4a, 4b.

For example, if the entrance chamber 37a side is lower and the entrance chamber 37b side is higher, each entrance chamber 37a.

Due to the difference in pressure supplied from 37b to each outlet chamber 39a, 39b, the piston 38 is biased to the left and moves. First, when the piston 38 moves by a distance L2, the valve body 2
9b is seated on the valve seat 28b, and the inlet chamber 38N) and the outlet chamber 3
Cut off communication with 9b. Even after this shutoff, when the pressure on the outlet chamber 391) side is higher than the pressure on the outlet chamber 39a side, the piston 38 moves further to the left and the 5-way outlet chamber 39
a.

It moves while changing the volume of surface opening chamber 39b until the pressures in the surface-protruding chambers 39a and 39b become equal. As a result, the pressure in the outlet chamber 39b decreases to the lower pressure in the outlet chamber 39a, and the pressure supplied from the outlet 13b to the adjustment part 6b of the hydraulic pressure control valve 6 is reduced to the pressure in the outlet 1-3a. equal to the pressure supplied from Conversely, if the pressure on the inlet chamber 37a side is higher than the pressure on the inlet chamber 37b side, the piston 38
moves to the right from its neutral position to reduce the high pressure in the outlet chamber 39a until it equals the lower pressure in the outlet chamber 391), causing a pressure equal to that from the outlet 13b from the outlet 13a.
is supplied to the hydraulic pressure control valve 6.

At this time, the pressure within each inlet chamber 378, 37b becomes lower than the pressure generated in the mask cylinder 3 due to the operation of the hydraulic pressure regulator 4. However, each stepped piston 21a
, 21b receives this pressure on the small pressure receiving area side, and further receives unreduced pressure from the master cylinder 3 on the large pressure receiving area side, so each stepped piston 2
1a.

21k) does not move from the center to the edge side,
In addition, in order to enable such operation, the piston 38
When the valves move from the neutral position to the left and right by a distance L2, each valve seat 29a, 29b moves to each valve seat 28a.

281), and L are set so that the passenger can sit on the seat. Flange portion 30 of each valve body 29a, 29b
a, 30b, and the reduced diameter portion 31a of each cylindrical member 25a, 25b.
, 31b is slightly larger than the distance L2. The distance L2 ensures a sufficient flow path between the valve seats 28a, 28b and the valve bodies 29a, 29b when the piston 38 is in the neutral position. It is as big as possible. Furthermore, the piston 38.

In order to equalize the pressure in the outlet chambers 39a and 39b, it moves to the left or right, but the effective amount of movement for pressure regulation is (L, -L2), and the pressure regulation ability is equal to this effective amount of movement. (Ll-L,) and the cross-sectional area of the piston 38. Therefore, it is necessary to make these values sufficiently large enough to correspond to the setting capability. And piston 38
When the valve bodies 29a, 29b move to the maximum and contact the sleeve 20 or the stepped portion 14N), the valve bodies 29a, 29b are moved to the shaft portions 38a, 38b.
In order to prevent compression and deformation between the protrusions 24a and 24b, the distance L4 at the neutral position (each valve body 29a,
Flange portions 30a, 30b of 29b and protrusion 24a
, 24b) is made slightly larger than the distance L1 (see equation (1) above).

・In case of failure, for some reason, the pressure chambers 3a and 3b of the mask cylinder 3
Assume that one of the two pressures does not generate hydraulic pressure, or even if hydraulic pressure does occur, a significantly large differential pressure occurs. For example, assume that no pressure is generated in the pressure chamber 3a. In that case, in the selection valve 10, pressure is not supplied to the inlet chamber 37a, outlet chamber 39a, and control chamber 35a belonging to the system connected to the pressure chamber 3a, and pressure is not supplied to the inlet chamber belonging to the system connected to the pressure chamber 3b. 371), the outlet chamber 39b, and the control chamber 351). This causes the piston 38 to move into the outlet chamber 39
In order to receive pressure only from b, move to the left and insert valve body 2.
9b is seated on the valve seat 28b, and further, in an attempt to equalize the pressure in the outlet chamber 39b to the pressure in the outlet chamber 39a,
It moves until it comes into contact with the sleeve 20. As a result, entrance chamber 3
7b to the outlet chamber 39b, and further attempts to make the pressure in the outlet chamber 391) pressureless.

However, although the stepped piston 21b, which receives the pressure in the inlet chamber 37b in a small pressure receiving area, receives the pressure in the control chamber 35a in a large pressure receiving area, since the pressure in the control chamber 35a is pressureless, the right side The cover member 15N) is moved towards the cover member 15N) and moves a distance and a height until it comes into contact with the cover member 15N). The movement of the stepped piston 211) is performed if the valve body 29b is moved to the valve seat 28.
Even if the person is seated on the cylinder member 25b, the reduced diameter portion 31 of the cylindrical member 25b
1) is engaged with the flange portion 30b of the valve body 29t) to forcibly move the valve body 29I) to the right.

As a result, the valve body 29t) separates from the valve seat 28N), and the inlet chamber 37t) and outlet chamber 39N) communicate with each other. Therefore,
Pressure can be supplied from the outlet chamber 39t) to the adjustment part 6t) of the hydraulic pressure control valve 6.

Conversely, if no pressure is generated on the pressure chamber 3b side, 1
Stepped piston 21. a is moved to the left by a distance L5, so that the valve body 29a cannot be seated on the valve seat 28a, and the inlet chamber 37a and the outlet chamber 39a are communicated with each other. Thereby, pressure can be supplied from the outlet chamber 39a toward the adjustment portion 6a of the hydraulic pressure control valve 6.

To enable such operation, the distance between the valve seats 28a and 28 when each stepped piston 21a and 21b moves is
In order to prevent the valve bodies 29a and 29b from seating on the distance B, the distance is set to be slightly larger than the value obtained by subtracting the distance L2 from the distance, or in other words, the distance is set to be slightly smaller than the sum of the distance and the distance L2. The movement of the stepped pistons 21a, 211) (see formula (2) above) that makes it impossible for the valve bodies 29a, 29b to sit on the valve seats 28a, 28b means that the pressure chamber of the mask cylinder 3 This is performed when the pressure difference between 3a and 3b becomes large. This may occur immediately after the start of braking (when no pressure is generated in one of the pressure chambers 3a, 3b from the beginning), or during braking or anti-skid action (when a sudden pressure drop occurs during braking). (when). In a system that normally generates pressure, even with the selection valve 10, pressure can be supplied to the rear wheel brake devices 7a, 7b, and only one of the front wheel brake devices [5a, 5b] It solves the situation of applying the brakes and can apply the brakes on one of the front wheels and one of the rear wheels.

According to the illustrated embodiment, therefore, the mask cylinder 3
If one of the pressure chambers 3a, 3b fails, the selection valve 10
function, one of the front wheels and one of the rear wheels,
That is, the brakes can be applied with the brake devices 5a and 7a or with the brake devices 5N) and 7b. others.

In the illustrated embodiment, when the failure in one system is recovered, the stepped pistons 21a and 21b automatically return to the normal position where the selection valve 10 performs its original function because the stepped pistons 21a and 21b have a difference in pressure receiving area. In particular, there is also an effect that the one-selection valve 10 does not need to be specially adjusted.

(Effect of the invention) According to this invention, the selection valve selects the lower pressure of the two systems and supplies it to the rear wheel brake system, but when one system is abnormal, the receiving pressure By prohibiting the shutoff of the valve due to the movement of movable bodies with different areas, the pressure of the normal system is supplied to the rear wheel braking device, so that the brakes can be applied on all wheels that have brake devices belonging to the normal system. I can do it.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a two-system anti-skid brake hydraulic pressure control device according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of the selection valve in FIG. 1. 1...Brake system, 3...Mask cylinder,
3a, 3b...pressure chamber, 1;a, 7b...brake device, 10...selection valve, 21a, 21b...stepped piston (movable body), 28a, 28b...valve seat. 29a, 29b... Valve body, 38... Screws 1 to 1.

Claims (1)

[Claims] 1 and 2 systems Two piping systems that independently supply hydraulic pressure from the master cylinder to the left and right front wheel brake devices, and supply hydraulic pressure to the left and right front wheel brake devices in response to commands from a discrimination circuit that monitors wheel behavior. A hydraulic pressure regulating device capable of regulating the hydraulic pressure is provided, and the pressure regulated by the hydraulic pressure regulating device is supplied to the left and right rear wheel brake devices, respectively, and two pipes are connected to the rear wheel brake device. A selection valve is provided across the piston, and the selection valve includes a piston that receives the pressure in the two piping oppositely on both end sides and is movable from the neutral position to each end side due to the differential pressure, and a piston on each side of the piston. The valves are provided opposite to each other, and open when the pistons are at the neutral position and the approach position, and close when the pistons move away from the neutral position, and control communication and isolation between the hydraulic pressure adjustment device and the rear wheel brake device. In a two-system anti-skid brake hydraulic pressure control device having a pair of valve devices, the pressure of the piping system to which it belongs is transmitted to the small pressure receiving surface at one end, and the pressure of the piping system to which it does not belong to the large pressure receiving surface at the other end. Providing movable bodies that face each other and receive pressure,
According to the movement of the movable body, each of the pair of valve devices in the selection valve is arranged so that communication with the rear wheel brake device in the piping system to which it belongs is not cut off even when the piston moves. Two-system anti-skid brake fluid pressure control device.