JPH0364342B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brake device for a vehicle, and more particularly to a brake device suitable for facilitating starting on an uphill road.

The applicant has previously proposed a system of this kind comprising at least two independent pressure sources, a first system connected to one of the pressure sources and comprising at least one wheel cylinder of a wheel brake, a second system connected to the power source and including at least one wheel cylinder of another wheel brake;
a brake holding valve that is provided in the system and is capable of maintaining the wheel cylinder side pressure of the first system in response to a stopping operation of a vehicle or the like on an uphill road;
an automatic valve that is provided in the brake holding valve system and is capable of holding the wheel cylinder side pressure of the second system in accordance with the holding of the wheel cylinder side pressure of the first system of the brake holding valve, Each of the wheel brakes belonging to the second system includes a rotating body that rotates together with the wheel, and a friction member that is pressed toward the rotating body when pressure is supplied to the wheel cylinder, and the brake The holding valve includes a valve seat provided toward the wheel cylinder side, a valve element that can be moved by its own weight and seated on the valve seat, and a valve element that can be moved to and from the valve seat in response to an on/off operation of a clutch device. The automatic valve has one end receiving the wheel cylinder side pressure of the automatic valve, the other end receiving the wheel cylinder side pressure of the brake holding valve, and the pressure acting on both ends. a differential piston movable by a differential; a valve seat provided facing the pressure source side; a valve member that seats and leaves the valve seat, and when the valve member is seated on the full meaning valve seat, fluid is allowed to move from the pressure source side of the automatic valve to the wheel cylinder side, and vice versa. A one-way valve is proposed.

This means that when the vehicle, etc. is stopped on an uphill road, the brake holding valve and automatic valve are closed even if the driver stops the brake operation and releases the pressure on the pressure source side while the driver is disconnecting the clutch device. The pressure on the wheel cylinder side belonging to the two systems is contained, and the wheel brakes are kept operating to keep the vehicle at a standstill.
This system releases the pressure contained in the wheel cylinders belonging to the two systems, thereby releasing the braking force acting on the wheels.

By the way, in the automatic valve for maintaining the pressure in the second system, the differential piston takes a position in which the valve member is separated from the valve seat when no pressure difference is generated between the two ends of the differential piston. , when the clutch device is disconnected and the brake operation is released on an uphill road, and the pressure source pressure of the second system decreases relative to the pressure held by the brake holding valve, the differential piston opens the valve. The member is moved from the position where it is unseated to the valve seat to the position where it is seated. Therefore, during the movement, a part of the pressure supplied to the wheel cylinders of the second system is released to the pressure source side, and the brakes to be held by the wheel brakes belonging to the second system are released accordingly. The power will also decrease.

On the other hand, as is generally known, the wheel brake can be roughly divided into two types:
One is a type that leaves a predetermined gap between the friction member and the rotating body when not in operation, and the other is a type that does not use a return spring as described above, and when the pressure in the wheel cylinder decreases, the seal ring for the piston is closed. Taking advantage of the fact that minute deformations are restored and that the rotating body is shaken in the direction of movement of the friction member,
There is a type in which the friction member is returned to a non-operating position with almost no gap formed between it and the rotating body. Comparing these two types, the former has the biasing force of the return spring acting on the friction member, and as a result, the friction member is quickly moved to the rotating body in response to the pressure drop in the wheel cylinder. It has the property of weakening the force pressing on the wheels and reducing the braking force acting on the wheels.

For this reason, in the above-mentioned brake system, when a type having the above-mentioned return spring is used as a wheel brake belonging to the second system, the differential piston moves the valve member to the valve seat as described above. Until the vehicle is moved to the seating position, the pressure supplied to the wheel cylinder side has a stronger tendency to decrease, even though the pressure on the wheel cylinder side of both the first and second systems is maintained. First, a problem arises in that a braking force commensurate with this cannot be maintained.

The present invention is an improvement of the brake device made in view of the above-mentioned problem, and the present invention maintains the pressure supplied to the wheel cylinder from the pressure source of the second system without reducing it, and maintains the pressure in the two systems. The purpose is to maintain sufficient braking force commensurate with the provision of a special valve.

This object, according to the invention, includes at least two independent pressure sources, a first system connected to one of the pressure sources and comprising at least one wheel cylinder of the wheel brake, and a first system connected to the other pressure source. a second system including at least one wheel cylinder of another wheel brake; a brake holding valve that can hold the brake holding valve; and a brake holding valve that is provided in the second system and that is capable of holding the wheel cylinder side pressure of the second system in response to the holding of the wheel cylinder side pressure of the first system of the brake holding valve. and an automatic valve, and each of the wheel brakes belonging to the first and second systems includes a rotating body that rotates together with the wheel, and a pressure being supplied to the wheel cylinder to push the wheel brake toward the rotating body. the brake holding valve has a friction member that is
A valve seat provided toward the wheel cylinder side, a valve element that can be moved by its own weight and seated on the valve seat, and a plunger that controls seating and removal of the valve element on and from the valve seat in accordance with on/off operations of a clutch device. The automatic valve receives the wheel cylinder side pressure of the automatic valve at one end, and receives the wheel cylinder side pressure of the brake holding valve at the other end, and the automatic valve receives the wheel cylinder side pressure of the automatic valve at one end, and the pressure difference acting between these ends causes a movable differential piston, a valve seat provided facing the pressure source side, and a valve seat that is supported by one end of the differential piston opposite to the valve seat and that moves in conjunction with the movement of the differential piston. a one-way valve that allows fluid to move from the pressure source side of the automatic valve to the wheel cylinder side and prohibits the reverse when the valve member is seated on the valve seat; A brake device having a wheel brake belonging to the second system is provided with a return spring that biases the friction member against the pressure supplied to the wheel cylinder, and when inactive, the The friction member is separated from the rotating body by a predetermined amount by the biasing force of a return spring, and the automatic valve is provided with a wheel cylinder side of the automatic valve having a predetermined distance. This is achieved by a brake device provided with a spring that constantly biases the differential piston toward the valve seat so as to be able to maintain a pressure smaller than the pressure required to close the valve seat.

That is, according to this, in the automatic valve provided in the second system, with the differential piston seating the valve member on the valve seat, the pressure of the pressure source is transferred to the wheel cylinder side via the one-way valve. Even if the pressure on the pressure source side of the automatic valve is released while the pressure is maintained on the wheel cylinder side of the brake holding valve, the pressure supplied to the wheel cylinder side of the automatic valve is The brake force is contained without any decrease, and the braking force by the wheel brakes belonging to the second system does not weaken.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The brake device of the present invention will be explained in detail below based on illustrated examples.

FIG. 1 is a diagram showing a brake device that is an embodiment of the present invention, and FIG. 2 is a sectional view taken in the direction of the line in FIG. 1.

In Figure 1, the brake system as a whole is 1
The device 1 has a brake tandem master cylinder 2 in which two independent hydraulic pressure generating chambers (not shown) are formed.

This master cylinder 2 is attached to the vehicle body A and is actuated by a brake pedal 3 swingably attached to the vehicle body A, and one hydraulic pressure generating chamber is connected to a first system, that is, a piping 4. , 5, 6 and a brake holding valve 7, and are connected to respective brake wheel cylinders (not shown) of a wheel brake 8 for the left front wheel and a wheel brake 9 for the right front wheel, and the other hydraulic pressure generating chamber is The second system, that is, the pipes 10, 11, 12 and the automatic valve 13 attached to the brake holding valve 7, is connected to each brake wheel cylinder (not shown) of the right rear wheel wheel brake 15 and the left rear wheel wheel brake 14. ).

According to this embodiment, the front wheel brakes 8 and 9 are of the disc brake type, and the rear wheel brakes 14 and 15 are of the drum brake type, and are of the front and rear piping type as shown in the figure. In addition, the drum brake type is equipped with a return spring that biases the friction member against the pressure supplied to the wheel cylinder, and when not in operation, the friction member is removed from the rotating body (which rotates with the wheel) due to the biasing force of the return spring. This is a typical example of a type in which the parts are separated by a predetermined distance.

First, the brake control valve 7 will be explained.
The valve 7 originally has a stepped hole 17 whose diameter gradually increases in the forward direction of the vehicle, etc., and a hole 18 perpendicular to the stepped hole 17 (first hole 16). ,
In FIG. 2, the forward direction of the vehicle, etc. is to the left when facing the figure. ) A camshaft 19 is rotatably inserted into the hole 18 , and the camshaft 19 has a hole 18 in the stepped hole 17 .
A cam 20 whose diameter is eccentrically reduced is provided at a portion opposite to the open end of the piping system. A cam chamber 23, which forms part of the cam chamber 23, is partitioned. This cam chamber 23 is connected to the pipe 4 via a connection hole 24.

A recess 25 is provided at the lower end of the camshaft 19 to increase the volume between the camshaft 19 and the closed end of the hole 18, while the upper end of the camshaft 19 has a reduced diameter to accommodate the hole 18. A connecting portion 26 protrudes outward,
In this connecting portion 26, a rotating member 27 having a substantially triangular shape is provided, together with a skirt member 28 for keeping out water.
It is attached using nuts 29 and washers 30.

A wire 31 is connected to one end of the rotating member 27, and a return spring 33 is stretched between the rotating member 27 and the vehicle body A at the other end. A clutch device (not shown) is connected to the opposite side of the wire 31 connected to the rotating member 27, and this device is activated by depressing and releasing the clutch pedal, but normally by its built-in preload spring. The clutch pedal is held in the "connected" position and the wire 31 is pulled to the left in FIG. 1, applying tensile stress to the return spring 33.

Further, the camshaft 19 is moved by a sliding member 35 supported by a stopper 34 provided at the open end of the hole 18.
It is prevented from coming out of the hole 18, and
The sliding movement during rotation is guided. 36 is waterproof,
These are dustproof boots.

On the other hand, a ball guide 38 having a spherical valve element 37 movable by its own weight is fitted in the large diameter hole of the stepped hole 17, and the ball guide 38 is fitted into the large diameter hole portion of the stepped hole 17. The main body 39 is held in the illustrated position in contact with the stepped portion 42 by a contact disk 57 that is in contact with the end surface of the main body 39 and a washer 41 with an elastic piece 40 provided between the disk 57 and the ball guide 38. has been done.

An axial groove 4 is provided on the inner surface of the ball guide 38.
3 are formed in large numbers, and a valve seat assembly 44, which serves as a valve seat on which the valve element 37 can be seated, is fitted into the end of the stepped portion 42.

This valve seat assembly 44 includes a seat member 45 made of rubber.
The ball guide 38 is made up of a support member 46 that is connected to the seat member 45 by unevenness, and the wall of the ball guide 38 is fitted into a groove 47 formed on the outer periphery of the valve member 45. Can be installed integrally. The seat member 45 has an annular protrusion (not shown) formed on the outer periphery to seal the space between the seat member 45 and the inner surface of the intermediate diameter portion of the stepped hole 17.
6 is formed with an inner hole 48 and a plate portion 50 that can come into contact with the stepped portion 49 of the stepped hole 17.

When the valve element 37 is seated on the seat member 45,
Movement of fluid from the wheel cylinder side of the wheel brakes 8, 9 to the master cylinder 2 side is prevented. However, when the hydraulic pressure on the master cylinder 2 side becomes higher than the hydraulic pressure on the wheel brakes 8 and 9 side, the valve element 3
7 is removed from the seat member 45, and fluid is allowed to move from the master cylinder 2 side to the wheel cylinder side of the wheel brakes 8 and 9.

In this way, the valve element 37 and the seat member 45 constitute a check valve whose forward direction is from the master ring 2 side to the wheel brakes 8 and 9 side.

A plunger 52 is movably inserted into the small diameter portion of the stepped hole 17 with a light spring 51 stretched between it and the support member 46 of the valve seat assembly 44. It is brought into contact with the cam 20 by the tension of 51. Further, the plunger 52 has a large number of grooves 53 formed in the axial direction on its outer periphery, and protrudes into the ball guide 38 through the valve seat assembly 44 on the left end side.
A small diameter portion 54 is formed that can come into contact with 7.

Reference numerals 55 and 56 are connection holes provided in communication with each other in the large diameter hole of the stepped hole 17, and the connection hole 55 is connected to the pipe 6, and the connection hole 56 is connected to the pipe 5, respectively.

Next, the automatic valve 13 disposed on the left side in FIG. 1 will be explained.

The main body 39 of the automatic valve 13 is attached to the main body 16 of the brake holding valve 7 by a bolt (not shown) with a seal ring 80 interposed therebetween. Main body 39
An inner hole 58 is formed in alignment with the stepped hole 17 of the main body 16 of the brake holding valve 7, and the right end side of the inner hole 58 is connected to a plurality of openings 5 formed in the communication disk 57.
9 communicates with the stepped hole 17 of the main body 16, and the left end side has a connection hole 60 to which the pipe 10 is connected, and the main body 3
It is formed in the end wall portion 64 of No. 9 and communicates with the connection holes 61 and 62 via the throttle hole 65. Connection hole 6
Pipes 11 and 12 are connected to 1 and 62, respectively.

A differential piston 63 equipped with a seal ring 81 is slidably inserted into the inner hole 58, and a valve retainer portion 6 is connected to the left end of the differential piston 63 through a reduced diameter portion 69.
6 is integrally formed. Valve retainer part 66
is substantially dish-shaped, and a valve rubber 68 as a valve member is mounted with a thin plate ring 70 interposed therebetween. The valve rubber 68 has a center hole 72, and a ring-shaped protrusion 68a is formed around the center hole 72. Also, the differential piston 63 is heated to the left by a light spring 67 stretched between the right end portion and the communication disk 57, and under normal conditions, the valve rubber 68 attached to the valve retainer portion 66 is heated. It is in contact with an end wall portion 64 of the main body 39 serving as a valve seat. Also, the valve retainer part 6
6 is formed with a plurality of small holes 71 located around the center hole 72 of the valve rubber 68, and is closed by the valve rubber 68 in the illustrated state, but the reduced diameter portion 69 of the differential piston 63 When a higher brake fluid pressure is generated in the first pressure chamber 73 formed around the ring-shaped projection 68a of the valve rubber 68 than in the second pressure chamber 74 formed inside the ring-shaped protrusion 68a of the valve rubber 68, the valve rubber 68 moves as shown in FIG. The brake fluid is deformed as shown by the dashed line, and the brake fluid flows from the first pressure chamber 73 into the second pressure chamber 74 through the small hole 71 of the valve retainer part 66 and the center hole 72 of the valve rubber 68. This brake fluid is sent from the second pressure chamber 74 to the rear wheel brakes 14, 15 through the throttle hole 65 and the connection holes 61, 62. Further, in the illustrated state, brake fluid cannot flow from the second pressure chamber 74 to the first pressure chamber 73. That is, the valve rubber 68, the inner end surface of the end wall portion 64 on which it is seated, and the valve retainer portion 66 move the pressure from the first pressure chamber 73, which is the pressure source side of the automatic valve 13, to the second pressure chamber 74, which is the wheel cylinder side. A one-way valve is configured that allows only the movement of liquid. Note that the biasing force of the spring 67 that biases the differential piston 63 to the left is applied to the wheel cylinders of the rear wheel brakes 14 and 15 at the brake force generation start pressure, that is, between the drum and the shoe (both not shown). The biasing force is set to be smaller than the urging force that maintains the pressure required to close the gap for a predetermined amount. That is, the sealing area of the valve rubber 68, that is, the ring-shaped protrusion 6
The area of the inner pressure receiving surface (second pressure receiving surface) of the differential piston 63 is smaller than the area of the pressure receiving surface (first pressure receiving surface) on the right end side of the differential piston 63, and the biasing force of the spring 67 is The applied force is set to be smaller than the applied force obtained by multiplying the braking force starting pressure by the area of the second pressure receiving surface. Therefore, although residual pressure is generated in the wheel cylinder even when the brake pedal 3 is not actuated, the biasing force of the spring 67 is set so that this residual pressure is not high enough to generate a braking force. The embodiment of the present invention is constructed as described above, and its operation will be explained next.

Assume that the driver of the vehicle is not operating the brake or clutch and is driving the vehicle at an appropriate speed.

Then, when the clutch is operated, the so-called clutch is connected, and the built-in load spring causes the camshaft 1 to
9 is biased to the illustrated position via the wire 31 and the rotating member 27, so that the plunger 52
is moved to the left by the cam 20, and the small diameter portion 54 of the plunger 52 is in a position where it protrudes into the ball guide 38 beyond the valve seat assembly 44. Valve element 37 attempts to seat on valve seat assembly 44 but is unable to do so. In addition, since the brake is not applied, no pressure is generated in the pipes 5 and 6, but the pressure is generated in the pipes 11 and 12 due to the spring force of the spring 67 that biases the differential piston 63 to the left. A certain residual pressure is generated. However, this residual pressure
Rear wheel brake 14,1 connected to 2
5 is not high enough to generate braking force.

While driving on an uphill road in this condition, for example, when the driver approaches a railroad crossing and depresses the brake pedal 3 to apply the brakes, pressurized fluid is discharged from the master cylinder 2 to the pipes 4 and 10, and each Pressure is generated in the piping system and pressurized fluid is supplied to the wheel cylinders of each brake device, so the brakes begin to apply. At this time, for the wheel brakes 8 and 9, the piping 4, the cam chamber 23, the plunger 52
The groove 53 of the valve seat assembly 44, the inner hole 48 of the valve seat assembly 44, the inside of the ball guide 38, and the pipes 5 and 6 are connected to the wheel brakes 14 and 15 through the pipe 10, the first pressure chamber 73, and the small hole 71. Also, the gap between the thin plate ring 70 and the valve retainer part 66, the second pressure chamber 74, the throttle hole 65, and the piping 11, 12 caused by the deformation of the valve rubber 68 as shown by the dashed line in FIG. Pressurized fluid is supplied independently from the master cylinder 2 through the cylinders.

In this state, the differential piston 63 receives substantially equal pressure on the left and right sides in equal pressure receiving areas, so it remains in the illustrated position without moving. (It is assumed that the pressures generated in the two hydraulic pressure generating chambers of the master cylinder 2 are substantially equal.) After that, when the vehicle etc. is sufficiently decelerated, the driver depresses the brake pedal 3 and presses the clutch pedal. Go deep. Then, the clutch device that is linked to the clutch pedal is in the so-called "clutch disengaged state."
At the same time, the wire 31 moves in the "off" direction as shown by the arrow, and the rotating member 27 of the brake holding valve 7 rotates clockwise in FIG. 2. That is, the rotation member 27 is rotated clockwise by the spring force of the return spring 33. In other words, the force of pressing the clutch pedal is assisted or reduced by the spring force of the return spring 33. Therefore, the clutch can be operated more quickly. As the rotating member 27 rotates, the cam shaft 19 rotates, and the cam 20 and the plunger 52 slide.
As the valve element 37 is deflected, the plunger 52 moves to the right due to the biasing force of the spring 51, and finally the valve element 37
The small system part 5 is arranged so that the valve seat assembly 44 can be seated.
Move until 4 is positioned sufficiently to the right.

In this state, when the vehicle etc. comes to a complete stop and the driver removes his foot from the brake pedal 3, the valve element 37
The piping 4 is separated by the contact area between the valve seat assembly 44 and the valve seat assembly 44.
The pressure on the side is released, but the pressure on the pipes 5 and 6, that is, the pressure on the wheel brakes 8 and 9, is maintained as it is.

On the other hand, in the automatic valve 13, the sealing area of the valve rubber 68, that is, the area of the inner pressure receiving surface (second pressure receiving surface) of the ring-shaped protrusion 68a is the same as that of the differential piston 6.
Since the area of the differential piston 63 is smaller than the area of the pressure receiving surface (first pressure receiving surface) on the right end side of the differential piston 63, the differential piston 63 is held at the illustrated position. Therefore, the pressure in the first pressure chamber 73 decreases as the pressure in the pipe 10 decreases, but brake fluid cannot flow from the second pressure chamber 74 side to the first pressure chamber 73 side.

As a result, pressure is maintained on the piping 11 and 12 sides as well. Therefore, in conjunction with the pressure being maintained in 5, 6, the wheel brakes 8, 9, 14, 1
Pressure is maintained in all 5 wheel cylinders. Note that since residual pressure is applied to the wheel brakes 14 and 15 in advance, the brakes can be operated more quickly.

Through the operations up to this point, the vehicle, etc. is kept in a stopped state with the clutch pedal being depressed, the clutch being disconnected, and the brakes being fully applied.

In such a situation, if the slope becomes large just before the vehicle comes to a stop, even if the hydraulic pressure is maintained as it was when the slope was small, there will be insufficient braking force and there is a possibility that the vehicle will move backwards. However, in this case, when the brake pedal 3 is depressed again and the pressure on the master cylinder 2 side becomes higher than the pressure on the wheel cylinder side, the valve rubber 68 deforms and the second pressure is released from the first pressure chamber 73. Pressure liquid will be supplied towards the chamber 74 and at the same time the valve element 37
The wheel brakes 8 and 9 are also separated from the valve seat assembly 44 so that pressurized fluid is supplied from the cam chamber 23 side to the ball guide 38 in response to the pressure difference acting in the front and rear directions. , 14, 15 are supplied with higher pressure, so
The lack of braking power will be resolved. After this, when the brake pedal 3 is removed again to stop the operation of the master cylinder 2, the pressure in the pipes 4, 10 is released, but the valve element 37
is seated on the valve material assembly 44 and the differential piston 63
Since the valve rubber 68 remains seated on the end surface of the end wall portion 64, pressure is maintained in each wheel cylinder and the stopped state is maintained.

Next, a case where the driver starts the vehicle will be described.

Now, as mentioned above, in order to start a vehicle from a stopped state by depressing only the clutch pedal, the driver must first depress the accelerator pedal (not shown) and raise the engine speed slightly. , the clutch pedal is in the inoperative position (return position)
Gradually return to side. The clutch device then enters a so-called half-clutch state. In addition, in the brake holding valve 7, the wire 31 moves in the direction of the clutch "contact" due to the spring force of the load spring built in the clutch device, and the rotating member 27 moves the return spring 33.
The cam 20 is deflected in response to the rotation in the counterclockwise direction against the biasing force of the cam 20 , and the plunger 52 is moved to bring the small diameter portion 54 of the plunger 52 into contact with the valve element 37 . By removing the valve from the valve seat assembly 44, the pressure within the pipes 5 and 6 is released to the master cylinder 2 side. As the pressure in the pipes 5 and 6 decreases, the differential piston 63 moves to the right in FIG. As a result, the valve rubber 68 is separated from the end wall portion 64, and the first pressure chamber 73 and the second pressure chamber 74 come into communication. Thus piping 1
Release the pressure on the 1 and 12 sides to the master cylinder 2 side.

As a result, driving force is transmitted to the wheels (driving wheels) from the engine via the clutch device, and the pressure in each wheel cylinder decreases, causing the braking force applied to the wheels to gradually decrease. Therefore, the vehicle or the like can finally start on the uphill road.

After starting, if you release the clutch pedal completely, the clutch will be fully engaged, and
The brake pressure in each wheel cylinder has also been released by then, resulting in normal driving conditions. Note that the differential piston 63 is
When the force pushing the valve to the right becomes smaller than the biasing force of the spring 67, the differential piston 63 moves to the left again, the valve rubber 68 seats on the end wall 64, and the second pressure chamber 74
The flow of brake fluid from the first pressure chamber 73 to the first pressure chamber 73 is stopped. In this way, a predetermined residual pressure remains on the pipes 11 and 12 side.

Furthermore, when starting, the brake fluid pressure on the pipes 5 and 6 side gradually decreases by gradually returning the clutch pedal and gradually moving the valve element 37, but this causes the differential piston 63 to move to the right. Even if the valve rubber 68 is separated from the end wall 64, the piping 11,1
The brake fluid from the second side gradually returns to the master cylinder 2 side due to the throttle passage 65, and therefore the brake fluid pressure on the pipes 5 and 6 side also gradually decreases. In this way, a smooth start is achieved.

As described above, various effects are achieved according to the embodiments described above, but the present invention can be implemented without being limited to the embodiments described above.

For example, in the above embodiment, a disc brake device was connected to the pipes 5 and 6, and a drum brake device was connected to the pipes 11 and 12, but a drum brake device was connected to all the pipes 5, 6, 11, and 12. may be done. The piping system is not the front-back piping system as in the embodiment, but may be any other type, such as an X-piping system.

Furthermore, the wheel brakes belonging to the piping system in which the automatic valve 13 is interposed are not limited to drum brakes, and wheel brakes of a type that may generate residual pressure, that is, friction members, are used to resist the pressure supplied to the wheel cylinders. The present invention is applicable to all types of wheel brakes that are provided with a biasing return spring, and in which the friction member is separated from the rotating body by a predetermined distance due to the biasing force of the return spring when not in operation.

As described above, in the brake device of the present invention, as is clear from the above, according to the present invention, pressure is supplied from the pressure source in the second system to the wheel cylinder by the automatic valve differential. Since the piston is operated via a one-way valve with the valve member seated on the valve seat, the pressure on the pressure source side of the second system decreases relative to the pressure held on the wheel cylinder side of the brake holding valve. In this case, the pressure on the wheel cylinder side of the automatic valve does not decrease accordingly, and the pressure supplied from the pressure source is contained in the wheel cylinder side of the second system as it is. Therefore, even if the wheel brake belonging to the second system is of a type in which the friction member is separated from the rotating body by the urging force of a return spring that resists the pressure of the wheel cylinder, the braking force acting on the wheel will not weaken. In addition to providing a brake holding valve in the first system, it is possible to maintain a braking force commensurate with providing an automatic valve in the second system.

In addition, when the brake is not applied, the differential piston of the automatic valve seats the valve member on the valve seat, and the spring biasing force biases the differential piston toward the valve seat toward the wheel cylinder side of the automatic valve. The pressure corresponding to the amount will be contained,
The automatic valve functions as a so-called residual pressure valve. For this reason,
In response to the increase in pressure on the pressure source side of the second system, the pressure on the wheel cylinder side quickly rises, and the friction member of the wheel brake is quickly pressed against the rotating body, resulting in the effect of speeding up the brake operation. play.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a brake device according to an embodiment of the present invention, FIG. 2 is a cross-sectional view along the - line in FIG. 1, and FIG. 3 is an enlarged cross-sectional view of a main part in FIG. 1. In the figure, 2... tandem master cylinder, 3... brake pedal, 4, 5, 6, 10,
11, 12... Piping, 7... Brake holding valve, 8
...Wheel brake of the left front wheel, 9...Wheel brake of the right front wheel, 13...Automatic valve, 14...Wheel brake of the left rear wheel, 15...Wheel brake of the right rear wheel, 1
9...Camshaft, 27...Rotating member, 33...Return spring, 37...Valve element, 44...Valve seat assembly, 52...Plunger, 63...Differential piston, 64...End wall portion , 66...valve retainer section,
67... Light spring, 68... Valve rubber, 68a...
Ring-shaped protrusion, 71... small hole, 72... central hole.

Claims (1)

[Claims] 1 a first system comprising at least two independent pressure sources and at least one wheel cylinder of a wheel brake connected to one of the pressure sources;
a second system that is connected to the other pressure source and includes at least one wheel cylinder of another wheel brake; and a second system that is provided in the first system, and that is connected to the first system in response to a stopping operation of the vehicle or the like on an uphill road. a brake holding valve capable of holding a wheel cylinder side pressure of the first system; an automatic valve capable of maintaining cylinder side pressure;
Each of the wheel brakes belonging to the second system includes a rotating body that rotates together with the wheel, and a friction member that is pressed toward the rotating body when pressure is supplied to the wheel cylinder, and The brake holding valve includes a valve seat provided facing the wheel cylinder side, a valve element that can be moved by its own weight and seated on the valve seat, and a valve element that is attached to and detached from the valve seat in response to an on/off operation of a clutch device. the automatic valve has a plunger for controlling the seat;
A differential piston that receives the wheel cylinder side pressure of the automatic valve at one end, receives the wheel cylinder side pressure of the brake holding valve at the other end, and is movable by the pressure difference acting on both ends, and a pressure source. a valve seat provided facing toward the side; a valve member supported by one end of the differential piston opposite to the valve seat and seated on and removed from the valve seat in conjunction with movement of the differential piston; A brake device comprising a one-way valve that allows fluid to move from the pressure source side of the automatic valve to the wheel cylinder side when the valve member is seated on the valve seat, and prohibits the reverse movement, A return spring is provided that biases the friction member of the wheel brake belonging to the second system against the pressure supplied to the wheel cylinder, and when not in operation, the friction member is biased by the biasing force of the return spring. The automatic valve is of a type that can be separated from the rotating body by a predetermined amount, and the automatic valve has a pressure higher than that required to fill the wheel cylinder side of the automatic valve with the predetermined amount of pressure. A brake device comprising a spring that constantly biases the differential piston toward the valve seat so as to maintain a small pressure.