JP2001328522A - Brake fluid pressure booster - Google Patents

Abstract

PROBLEM TO BE SOLVED: To arrange an operation piston and a cut valve in the cylinder body of a secondary master cylinder by shortening the length of the secondary master cylinder as short as possible in a brake fluid pressure booster capable of boosting a wheel brake. SOLUTION: The operation piston 58 of the secondary master cylinder M2F has both ends facing to an output fluid pressure chamber 59 connected to the wheel brake and a first input fluid pressure chamber 60 connected to the proportional booster valve V, is formed with an annular second input fluid pressure chamber 61 connected to the primary master cylinder in a space relative to the internal circumference of the cylinder hole 56 provided in the cylinder body 55, and slidingly fitted to the cylinder hole 56. The cut valve 65 is provided in the operation piston 58 so as to cut off between the second input fluid pressure chamber 61 and the output fluid pressure chamber 59 according to the fluid pressure increase of the first input fluid pressure chamber 60.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic booster for a brake capable of boosting a wheel brake, and more particularly to a primary master cylinder for outputting a hydraulic pressure corresponding to a brake operation input. , A hydraulic pressure source, a proportional booster valve that draws a booster hydraulic pressure according to the output hydraulic pressure of the primary master cylinder from the hydraulic pressure source and outputs the booster hydraulic pressure, and a brake fluid according to the booster hydraulic pressure output by the proportional booster valve. Activate wheel brakes with pressure 2
The present invention relates to an improvement of a vehicle equipped with a next master cylinder.

[0002]

2. Description of the Related Art Conventionally, such a hydraulic pressure booster is already known, for example, from Japanese Patent Publication No. 61-53265.

[0003]

SUMMARY OF THE INVENTION In the above prior art,
In the cylinder body of the secondary master cylinder, the working piston and the cut valve are arranged side by side in the axial direction, and the length of the cylinder body, that is, the secondary master cylinder in the direction along the axis of the working piston is increased. Would.

The present invention has been made in view of such circumstances, and the working piston and the cut valve can be arranged in the cylinder body of the secondary master cylinder so that the length of the secondary master cylinder can be reduced as much as possible. It is an object of the present invention to provide a brake hydraulic booster as described above.

[0005]

In order to achieve the above object, the present invention is directed to a primary master cylinder which outputs a hydraulic pressure in response to a brake operation input, and an output hydraulic pressure of the primary master cylinder. A hydraulic pressure source capable of outputting a higher hydraulic pressure regardless of the presence or absence of a brake operation, and a proportional pressure increase valve that draws a hydraulic pressure proportional to the output hydraulic pressure of the primary master cylinder from the hydraulic pressure source and outputs the hydraulic pressure. 2 connected to the wheel brake so as to output a hydraulic pressure corresponding to the output hydraulic pressure of the proportional pressure increasing valve
A brake hydraulic booster comprising: a secondary master cylinder; and a cut valve that shuts off between the primary master cylinder and a wheel brake in response to an increase in the output hydraulic pressure of the proportional booster valve. The first master has both ends facing a cylinder body having a cylinder hole closed at both ends, an output hydraulic chamber connected to the wheel brake, and a first input hydraulic chamber connected to the proportional pressure increasing valve. An annular second input hydraulic chamber connected to the cylinder is formed between the second input hydraulic chamber and the inner periphery of the cylinder hole, and an operating piston slidably fitted in the cylinder hole; A return spring for urging the working piston toward the side of reducing the volume, wherein the cut valve is adapted to increase the hydraulic pressure of the first input hydraulic chamber and to increase the hydraulic pressure of the first input hydraulic chamber. I will shut off A manner, and which are located in the working piston.

[0006] According to this configuration, the hydraulic pressure output from the proportional pressure increasing valve in response to the operation of the primary master cylinder in response to the brake operation input is cut in accordance with the action on the first input hydraulic pressure chamber. The valve is closed, and the boosting hydraulic pressure is applied to the wheel brake from the output hydraulic pressure chamber by the working piston that is advanced by the hydraulic pressure of the first input hydraulic pressure chamber, and proportionally increases due to malfunction of the hydraulic pressure source. When the booster pressure cannot be obtained with the pressure valve, the output hydraulic pressure of the primary master cylinder is applied to the wheel brake from the output hydraulic chamber of the secondary master cylinder because the cut valve remains open. Can be. Moreover, since the cut valve is provided in the working piston, the length of the cylinder body, that is, the secondary master cylinder can be reduced.

[0007] The invention according to claim 2 provides the above-described claim 1.
In addition to the configuration of the invention described, the cylinder hole has a large-diameter hole having one end closed, and a small-diameter hole having one end coaxially connected to the other end of the large-diameter hole and the other end closed. The working piston is formed stepwise, and the working piston forms the output hydraulic pressure chamber between itself and the one-end closing portion of the large-diameter hole, and is slidably fitted to the large-diameter hole. The first input hydraulic chamber is formed between the large-diameter piston portion and the other-end closing portion of the small-diameter hole portion, and the small-diameter piston portion slidably fitted to the small-diameter hole portion is provided.
According to this configuration, the hydraulic pressure output from the proportional pressure increasing valve is characterized by being integrally connected by a connecting shaft portion that forms an annular second input hydraulic chamber between the cylinder and the inner surface of the cylinder hole. When the working piston moves forward in response to the action on the first input hydraulic chamber, the operation stroke of the operating member for operating the primary master cylinder is secured by increasing the volume of the second input hydraulic chamber. Can be.

According to a third aspect of the present invention, in addition to the configuration of the first or second aspect, the cut valve opposes a force in a valve closing direction due to hydraulic pressure of the first input hydraulic chamber. And a set load of the return spring and the valve spring, wherein the set load of the return spring and the valve spring is caused by the hydraulic pressure of the first input hydraulic chamber to the side that reduces the volume of the output hydraulic chamber. It is characterized in that the cut valve is set to close before the movement of the working piston, and according to such a configuration, the cutoff valve is switched from the proportional pressure increasing valve in accordance with the operation of the primary master cylinder accompanying the brake operation input. The cut valve is first closed in response to the output of the hydraulic pressure, so that the boosted hydraulic pressure from the proportional pressure increasing valve can be efficiently transmitted to the wheel brake.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on one embodiment of the present invention shown in the attached drawings.

FIGS. 1 to 4 show an embodiment of the present invention. FIG. 1 is a hydraulic circuit diagram of a hydraulic booster for a brake.
FIG. 2 is a longitudinal sectional view showing the configuration of the proportional booster valve and the front secondary master cylinder, FIG. 3 is a longitudinal sectional view of the rear secondary master cylinder, and FIG. 4 is a brake fluid pressure characteristic diagram.

First, in FIG. 1, a primary master cylinder M
Reference numeral 1 denotes a tandem type having a cylinder body 1 and a front piston 2 and a rear piston 3 slidably fitted in the cylinder body 1. 4 are connected.

A front piston 2 is provided in a cylinder body 1.
A front hydraulic chamber 5F facing the front end of the piston and a rear hydraulic chamber 5R between the front and rear pistons 2 and 3 are formed, and the front and rear hydraulic chambers 5F and 5R have pistons 2 and 2, respectively. The return springs 6F and 6R for urging the front return spring 3 in the backward direction are respectively housed, and the set load of the front return spring 6F is set to be weaker than the set load of the rear return spring 6R. The cylinder body 1 has a front output port 7F communicating with the front hydraulic chamber 5F and a rear output port 7F communicating with the rear hydraulic chamber 5R.
R is provided.

In such a primary master cylinder M1,
When the rear piston 3 is pushed forward by applying a depressing force to the brake pedal P, the front return spring 6F is first compressed and a hydraulic pressure is generated in the front hydraulic chamber 5F, and the hydraulic pressure becomes a predetermined value. Is reached, the rear return spring 6R is compressed, and hydraulic pressure is generated in the rear hydraulic chamber 5R. That is, in the primary master cylinder M1, after the hydraulic pressure is output from the front output port 7F, the hydraulic pressure is output with a delay from the rear output port 7R.

The front output port 7F is connected to a proportional pressure increasing valve V via a front hydraulic pressure passage 8F, and a front secondary master cylinder M2F which operates by receiving the output hydraulic pressure of the proportional pressure increasing valve V is used for proportionally increasing the pressure. It is provided in parallel with the pressure valve V. The rear output port 7R is also connected to the proportional booster valve V via the rear hydraulic pressure passage 8R. The rear secondary master cylinder M2R that operates by receiving the output hydraulic pressure of the proportional booster valve V is separated from the proportional booster valve V. It is arranged.

A pair of front wheel brakes BFL and BFR for braking left and right front wheels are connected to a front output path 9F extending from the front secondary master cylinder M2F, and extend from the rear secondary master cylinder M2R. Rear output path 9R
A pair of rear wheel brakes B for braking the left and right rear wheels
RL and BRR are connected.

A hydraulic pressure source 12 composed of a hydraulic pump 10 driven by an electric motor (not shown) and an accumulator 11 for accumulating the discharge hydraulic pressure is connected to the proportional pressure increasing valve V. The hydraulic pressure of the accumulator 11 is detected by the hydraulic pressure sensor 13, and when the detected hydraulic pressure becomes lower than the lower limit, the hydraulic pump 10 starts operating, and when the detected hydraulic pressure becomes higher than the upper limit, the hydraulic pump 10 stops operating. .

The suction side of the hydraulic pump 10 is connected to a reservoir 15 of the primary master cylinder M1 via a suction passage 14. That is, the hydraulic pressure source 12 pumps the brake fluid from the reservoir 15, and the primary master cylinder M1
Is connected to the proportional pressure increasing valve V so that a hydraulic pressure higher than the output hydraulic pressure can be output regardless of the presence or absence of the brake operation.

In FIG. 2, a housing 17 of the proportional pressure increasing valve V includes a housing main portion 18 and the housing main portion 18.
A cap 20 having a bottomed cylindrical shape joined to one end of the housing with a partition plate 19 interposed therebetween, and a lid plate 21 joined to the other end of the housing main portion 18.

The cap 20 is provided with a bottomed cylinder hole 22 whose opening end is closed by the partition plate 19, and a control piston 23 and a free piston 24 slidable relative to the control piston 23 in the axial direction. Is slidably fitted in the cylinder hole 22.

The control piston 23 is
And one end facing a first control hydraulic chamber 25 formed in the cylinder hole 22 between the free piston 24 and
The free piston 2 is slidably fitted in the cylinder hole 22 with the other end facing the atmospheric pressure chamber 26 on the partition plate 19 side.
4 is the second control hydraulic chamber 2 between the closed end of the cap 20 and
7 are slidably fitted in the cylinder hole 22, and both ends of the free piston 24 face the second control hydraulic chamber 27 and the first control hydraulic chamber 25.

The free piston 24 includes a control piston 23
The control piston 23 is integrally formed at one end thereof with a small-diameter piston portion 23a fitted to the free piston 24 so as to be relatively slidable. Moreover, a plurality of grooves 28 for guiding the brake fluid smoothly between the free piston 24 and the small-diameter piston portion 23a are provided on the outer periphery of the small-diameter piston portion 23a.

The free piston 24 operates so that the hydraulic pressures of the first and second control hydraulic chambers 25 and 27 are balanced, and the hydraulic pressure of the first control hydraulic chamber 25 is reduced to the second control hydraulic pressure. As the hydraulic pressure in the chamber 27 decreases, the pressing force acts directly from the free piston 24 to one end of the control piston 23.

The first control hydraulic pressure chamber 25 has a pair of output ports 7F, 7R provided in the primary master cylinder M1.
Of these, the output port with the earlier output generation time, that is, the front output port 7F is connected via the front hydraulic pressure path 8F, and the second control hydraulic chamber 27 is connected to the primary master cylinder M1.
The remaining output port of the pair of output ports 7F and 7R provided in the above, that is, the rear output port 7R is connected via the rear hydraulic pressure path 8R.

A pair of lip seals 30 and 31 are provided on the outer periphery of the free piston 24 so as to be in sliding contact with the cap 20 constituting a part of the housing 17 so as to always communicate between the lip seals 30 and 31. Cylinder hole 2
A drain passage 32 having an open end on the inner surface of the cap 2 is provided in the cap 20 such that the other end communicates with the atmospheric pressure chamber 26. That is, the space between the lip seals 30 and 31 is open to the atmosphere.

The housing main part 18 is provided with a storage hole 33 whose one end is closed by the partition plate 19 and a mounting hole 35 eccentric to the storage hole 33 with a partition 36 interposed therebetween. An opening end of the side 35 opposite to the partition 36 is closed by the cover plate 21. Moreover, the mounting hole 35 is formed stepwise so as to gradually increase in diameter as it is separated from the partition wall 36 at a position eccentric to the storage hole 33. In the partition 36, a sliding hole 34 connecting the storage hole 33 and the mounting hole 35 is provided coaxially with the storage hole 33.

A first reaction force piston 37 is accommodated in the accommodation hole 33 so as to be movable in the axial direction, and a second reaction force piston 38 forming reaction force means 40 in cooperation with the first reaction force piston 37. Is slidably fitted to enable relative sliding with the first reaction force piston 37, and a second reaction force piston 38 is provided between the partition plate 19 and the second reaction force piston 38 on the partition wall 36 side. A reaction force spring 39 for exerting a biasing spring force is provided.

The base end of a small-diameter portion 38a formed in a cylindrical shape so as to be slidably fitted in the sliding hole 34 is coaxially and integrally connected to the second reaction force piston 38. The first reaction force piston 37 has a small diameter portion 3 of the second reaction force piston 38.
8a, a cylindrical small-diameter portion 37 slidably fitted into the portion 8a.
The base end of a is coaxially and integrally connected. In addition, the second reaction force piston 38 is formed with a contact surface 38b that can contact the first reaction force piston 37, facing one end side.
The reaction force piston 37 is fitted to the second reaction force piston 38 in a liquid-tight and relatively slidable manner.

On the other hand, the control piston 23 has a partition plate 19
A small shaft 23b penetrating through a through hole 41 formed in the center of the first member and abutting on the end face of the first reaction force piston 37 opposite to the small diameter portion 37a is integrally provided to project therefrom. Through this, the control piston 23 can push the first reaction force piston 37.

In the mounting hole 35, a valve housing 42 is fixedly mounted. As a result, a booster hydraulic chamber 44 is defined in the mounting hole 33 between the partition wall 36 and the valve housing 42. Thus, the tip of the small diameter portion 37a of the first reaction force piston 37 and the tip of the small diameter portion 38a of the second reaction force piston 38 face the boosting hydraulic pressure chamber 44, and the first reaction force piston 37 is boosted. The reaction force corresponding to the hydraulic pressure of the hydraulic pressure chamber 44 is constantly transmitted to the control piston 23, and the second reaction force piston 38 causes the hydraulic pressure of the boosted hydraulic pressure chamber 44 to exceed the set hydraulic pressure determined by the reaction force spring 39. Accordingly, a reaction force corresponding to the hydraulic pressure of the booster hydraulic pressure chamber 44 is transmitted to the control piston 23.

The cylinder main portion 18 is provided with an open port 45 which opens to the inner surface of the cylinder hole 33, and a return path 46 leading to the open port 45 is connected to the suction path 14. Thereby, each part in the cylinder hole 33 communicating with the atmospheric pressure chamber 26 through the through hole 41 is connected to the reservoir 15.

The valve housing 42 is provided with an inlet valve 48 for opening and closing between a hydraulic pressure path 47 extending from the accumulator 11 of the hydraulic pressure source 12 and the boosting hydraulic pressure chamber 44. The inlet valve 48 has a small diameter portion 37 provided in the first reaction force piston 37.
a having a valve-opening rod 49 pushed by the tip of a.
Since the first reaction force piston 37 operates together with the control piston 23, the first reaction force piston 37 opens and closes according to the operation of the control piston 23.
That is, when the control piston 23 is operated to reduce the volume of the booster hydraulic pressure chamber 44, the valve opening rod 49 is pushed by the first reaction force piston 37 to open the inlet valve 48,
The hydraulic pressure path 47, that is, the hydraulic pressure source 12 is communicated with the boosting hydraulic pressure chamber 44, and the inlet valve 48 is closed in response to the control piston 23 operating to increase the volume of the boosting hydraulic pressure chamber 44. I do.

The first reaction force piston 37 has the inlet valve 4
An outlet valve 51, which constitutes valve means 50 in cooperation with 8, is provided so as to open and close between the inside of the cylinder hole 33 communicating with the reservoir 15 and the booster hydraulic pressure chamber 44. The outlet valve 51 has a valve-opening rod 52 that can abut on the partition plate 19, and opens and closes according to the operation of the control piston 23. That is, as the first reaction force piston 37 separates from the partition plate 19 with the operation of the control piston 23 to the side where the volume of the booster hydraulic chamber 44 is reduced, the outlet valve 51 closes, and In response to the operation of the control piston 23 to increase the volume of the power hydraulic chamber 44, the first reaction force piston 37
When the valve retreats so as to approach 9, the valve opening rod 52 is pushed by the partition plate 19 to open the outlet valve 51, and the boosting hydraulic pressure chamber 44 communicates with the reservoir 15.

The front secondary master cylinder M2F has a cylinder body 55 formed integrally with the housing main part 18 of the proportional pressure increasing valve V and a closed end of a bottomed cylinder hole 56 provided in the cylinder body 55. And an end plate 57 fastened to the cylinder body 55.

The cylinder hole 56 has a large-diameter hole 56a having one end closed by an end plate 57, one end coaxially connected to the other end of the large-diameter hole 56a, and the other end connected to the end wall of the cylinder hole 56. And has a small-diameter hole portion 56b which is closed. An operation piston 58 is slidably fitted in the cylinder hole 56. The operation piston 58 forms an output hydraulic chamber 59 between the cylinder piston 56 and one end of the large-diameter hole 56a. A first input hydraulic chamber 60 is formed between the large-diameter piston portion 58a slidably fitted in the large-diameter hole portion 56a and the other end closing portion of the small-diameter hole portion 56b, and is formed in the small-diameter hole portion 56b. A small-diameter piston portion 58b slidably fitted and a cylinder hole 5
6 is formed between the large-diameter piston portion 58a and the small-diameter piston portion 58b.
A connecting shaft portion 58c for connecting between them is integrally provided.

The output hydraulic pressure chamber 59 is connected to a front output path 9F connected to the front wheel brakes BFL and BFR.
Further, the output hydraulic chamber 59 houses a return spring 62 for urging the working piston 58 to increase the volume of the output hydraulic chamber 59, that is, reduce the volume of the first input hydraulic chamber 60.

The main housing 18 of the proportional pressure increasing valve V and the cylinder body 55 of the front secondary master cylinder M2F
Is provided with a communication passage 63 for communicating the booster hydraulic pressure chamber 44 of the proportional booster valve V with the first input hydraulic pressure chamber 60 of the front secondary master cylinder M2F, and a booster output from the proportional booster valve V. The hydraulic pressure is the first input hydraulic chamber 6 of the front secondary master cylinder M2F.
Acts on 0.

The first control hydraulic pressure chamber 25 of the proportional pressure increasing valve V is connected to the second input hydraulic pressure chamber 61 through a communication pipe 64. As a result, the output hydraulic pressure of the front output port 7F of the primary master cylinder M1 acts on the second input hydraulic chamber 61 via the first control hydraulic chamber 25 and the communication pipe 64.

In the working piston 58, the primary hydraulic pressure between the primary master cylinder M1 and the front wheel brakes BFL, BFR increases as the output hydraulic pressure of the proportional pressure increasing valve V, that is, the hydraulic pressure of the first input hydraulic chamber 60 increases. Is provided with a cut valve 65 for shutting off.

The cut valve 65 has a valve hole 66 provided at the center of the operating piston 58 through the output hydraulic pressure chamber 59 and a valve seat 67 having the valve hole 66 opened at the center at the inner end. And a sliding hole 68 provided coaxially with the working piston 58 so as to open the outer end to the first input hydraulic chamber 60.
A valve piston 69 which is slidably fitted in a sliding hole 68 with a valve chamber 70 formed between the valve seat 67 and the outer end facing the first input hydraulic chamber 60, A spherical valve body 71 fixed to the inner end of the valve piston 69 to enable seating on the valve seat 67, and exerts a spring force for urging the valve piston 69 in a direction in which the valve body 71 is separated from the valve seat 67. Valve room 70
And a valve spring 72 housed therein.

Further, the orifice 73 for restricting the flow of the brake fluid is interposed between the primary master cylinder M1 and the valve chamber 70 of the cut valve 65, in this embodiment, between the second input hydraulic chamber 61 and the valve chamber 70. Working piston 58
, And the valve chamber 70 communicates with the second input hydraulic chamber 61 via the orifice 73.

According to the cut valve 65, the hydraulic pressure output from the proportional pressure increasing valve V in response to the operation of the primary master cylinder M1 is cut in response to the action on the first input hydraulic chamber 60. The valve 65 is closed, and the connection between the second input hydraulic chamber 61 and the output hydraulic chamber 59 is shut off. Moreover, the working piston 58
The set load of the return spring 62 and the valve spring 72 that urges the valve is moved prior to the movement of the working piston 58 by the hydraulic pressure of the first input hydraulic chamber 60 to the side where the volume of the output hydraulic chamber 59 is reduced. The cut valve 65 is set to close.

When the cut valve 65 is opened, the front wheel brakes BFL, BFR are connected to the output path 9F, the output hydraulic chamber 59 of the front secondary master cylinder M2F, the valve chamber 70 of the cut valve 65, the orifice 73, The second input hydraulic chamber 61, the communication pipe 64, the first control hydraulic chamber 25 of the proportional pressure increasing valve V, and the front hydraulic pressure passage 8F communicate with the primary master cylinder M1. The brakes BRL and BRR are connected to the output passage 9R and the output hydraulic chamber 5 of the rear secondary master cylinder M2R.
9, communicates with the primary master cylinder M1 via the valve chamber 70 of the cut valve 65, the orifice 73, the second input hydraulic chamber 61, and the rear hydraulic passage 8R. Therefore, each wheel brake BFL, BFR, BRL, B
The volume change at RR can be absorbed by the primary master cylinder M1.

The large-diameter piston portion 58a of the working piston 58 is provided with a plurality of communication holes 75 communicating with the second input hydraulic chamber 61, and a lip for allowing the communication holes 75 to face the rear surface. The seal 76 allows the brake fluid to flow from the second input hydraulic chamber 61 to the output hydraulic chamber 59 as the hydraulic pressure of the output hydraulic chamber 59 becomes lower than the hydraulic pressure of the second input hydraulic chamber 61. Large-diameter piston portion 58a
Attached to.

In FIG. 3, the rear secondary master cylinder M
2R, the cylinder body 55 'is disposed independently of the housing main portion 18 of the proportional pressure increasing valve V, and the first input hydraulic chamber 60 is connected to the front secondary master cylinder M2F via the communication line 74. Communicating with the first input hydraulic chamber 60,
Except that the rear output passage 9R connected to the rear wheel brakes BRL, BRR is connected to the output hydraulic pressure chamber 59, it has basically the same configuration as the front secondary master cylinder M2F. Only the parts corresponding to the secondary master cylinder M2F are denoted by the same reference numerals as shown in FIG. 3 and detailed description of the configuration of the rear secondary master cylinder M2R is omitted.

Next, the operation of this embodiment will be described. The hydraulic pressure output from both output ports 7F and 7R of the primary master cylinder M1 operated by the brake operation input is equal to the both ends of the free piston 24 at the proportional pressure increasing valve V. Act on. Thereby, the hydraulic pressure of the first control hydraulic chamber 25 between the control piston 23 and the free piston 24 and the second control hydraulic chamber facing the end face of the free piston 24 on the side opposite to the first control hydraulic chamber 25. The free piston 24 operates so as to balance the hydraulic pressure of the control piston 27 with the control piston 23.
The pressing force corresponding to the hydraulic pressures of the first and second control hydraulic chambers 25 and 27 that are mutually balanced acts.

On the other hand, the hydraulic pressure in the booster hydraulic chamber 44 is
0 to the control piston 23 and the booster hydraulic pressure chamber 44
The hydraulic pressure of the hydraulic pressure source 12 is drawn out by the valve means 50 in accordance with the axial movement of the control piston 23 according to the hydraulic pressure of the first control hydraulic pressure chamber 25, and from the boosting hydraulic pressure chamber 44. A pressing force acting on the control piston 23, that is, a boosted hydraulic pressure proportional to the above-mentioned balanced hydraulic pressure is output.

By operating the front and rear secondary master cylinders M2F and M2R with the output hydraulic pressure of the proportional pressure increasing valve V, each wheel brake BFL, BFR, BRL,
BRR can be braked strongly. In addition, since the pair of secondary master cylinders M2F and M2R are operated by the boosted hydraulic pressure output by the single common proportional booster valve V, the sliding resistance of the operating member in the proportional booster valve V does not affect the pair of secondary master cylinders M2F and M2R. The secondary master cylinders M2F and M2R are always boosted simultaneously, and all wheel brakes BFL and BF are operated.
R, BRL and BRR can be operated simultaneously.
As a result, the number of components can be reduced by using only one proportional pressure increasing valve V, and the configuration can be simplified and the cost can be reduced.

The free piston 24 having both ends facing the first control hydraulic chamber 25 and the second control hydraulic chamber 27
As the hydraulic pressure of the control hydraulic chamber 25 becomes lower than the hydraulic pressure of the second control hydraulic chamber 27, the pressing force can be directly exerted on one end of the control piston 23. 25, the control piston 23 can be pressed by the free piston 24 based on the hydraulic pressure in the second control hydraulic chamber 27, and the second control hydraulic Even if a hydraulic pressure failure occurs in the hydraulic system communicating with the pressure chamber 27, the control piston 23 can be pressed as long as the hydraulic pressure in the first control hydraulic chamber 25 is normal, and the hydraulic pressure at the proportional pressure increasing valve V Boost function can be maintained.

Since the output port 7F of the primary master cylinder M1 which has the earlier output generation time is connected to the first control hydraulic pressure chamber 25, the control piston 23 of the proportional pressure increasing valve V is connected to the control piston 23. In addition, the output hydraulic pressure of the primary master cylinder M1 is made to act quickly, and the responsiveness of the proportional pressure increasing valve V to the braking operation can be improved.

The free piston 24 is formed in a cylindrical shape with a bottom opening to the control piston 23 side, and the small-diameter piston portion 2 provided integrally at one end of the control piston 23.
3a is fitted to the free piston 24 so as to be relatively slidable, so that the axial lengths of the pistons 23, 24 are set to be short while the axial movement of the pistons 23, 24 is ensured. The pistons 23 and 24 can be supported, which contributes to the downsizing of the proportional pressure increasing valve V.

Further, a pair of lip seals 30 and 31 slidably in contact with a cap 20 constituting a part of the housing 17 provided in the proportional pressure increasing valve V are mounted on the outer periphery of the free piston 24, and a gap between the lip seals 30 and 31 is provided. The cap 20 is provided with a drain passage 32 that is open to the atmosphere, so that the vehicle driver can recognize that a seal abnormality has occurred on the outer periphery of the free piston 24, and the entire brake hydraulic circuit is caused by the abnormality. Can be prevented from becoming one system.

That is, both lip seals 3
When one of 0 and 31 is damaged, for example, 31, the hydraulic pressure is released to the atmosphere in the hydraulic system connected to the control hydraulic chamber 27 on the side of the damaged lip seal 31, so that the operation stroke of the primary master cylinder M1 becomes large. Therefore, the vehicle driver can be made aware that a failure has occurred. In addition, since the control piston 23 can be pushed despite the decrease in the hydraulic pressure in one of the two control hydraulic chambers 25 and 27, the boosting function can be reliably exhibited. On the other hand, when a single annular seal member is mounted on the outer periphery of the free piston 24, the entire brake hydraulic circuit becomes one system due to the abnormality of the annular seal member, and any one of the entire brake hydraulic circuits is used. Can not cope with the occurrence of hydraulic pressure failure.

The reaction force means 40 of the proportional pressure increasing valve V
A first reaction force piston 37 which constantly transmits the hydraulic pressure of the booster hydraulic pressure chamber 44 to the control piston 23 as a reaction force;
And a second reaction force piston 38 which constantly transmits the hydraulic pressure of the boosted hydraulic pressure chamber 44 as a reaction force to the control piston 23 after the hydraulic pressure of the first master exceeds the set hydraulic pressure. In the initial stage of the operation of the cylinder M1, the hydraulic pressure in the booster hydraulic chamber 44 acts as a reactive force on the control piston 23 only by the first reaction force piston 37, and the hydraulic pressure in the booster hydraulic chamber 44 exceeds the set hydraulic pressure. After that, the hydraulic pressure in the booster hydraulic chamber 44 acts on the control piston 23 as a reaction force by the first and second reaction force pistons 37 and 38. Therefore, in the initial stage of the operation of the primary master cylinder M1, as shown in FIG. 4, the output from the proportional pressure increasing valve V, that is, the output of the secondary master cylinders M2F and M2R can be jumped, and an elastic material such as rubber can be used. Since it is not used, it is possible to avoid a change in the hydraulic characteristics due to a change in temperature and to obtain a stable hydraulic characteristic at all times.

A first reaction force piston 37 having one end connected to the control piston 23 and the other end facing the booster hydraulic pressure chamber 44 has an abutment surface 38b which can abut the first reaction force piston 37. The first and second reaction force pistons 38 are formed so as to face one end side and face the other end to the booster hydraulic chamber 44 so as to be liquid-tight and relatively slidable. Despite the provision of the two reaction force pistons 37, 38, it is possible to suppress the length of the proportional pressure increasing valve V along the axial direction of the reaction force pistons 37, 38 from increasing.

On the other hand, the secondary master cylinders M2F and M2R
Are cylinder bodies 55, 55 'having cylinder holes 56 closed at both ends, and corresponding wheel brakes BFL, BF.
R; an annular second input connected to the primary master cylinder M1 with both ends facing the output hydraulic chamber 59 connected to the BRL and BRR and the first input hydraulic chamber 60 connected to the proportional pressure increasing valve V. A hydraulic piston 61 is formed between the inner periphery of the cylinder bore 56 and the working piston 58 slidably fitted in the cylinder bore 56, and a hydraulic pressure chamber 61 is formed on the side for reducing the volume of the first input hydraulic chamber 60. A return spring 6 for biasing the working piston 58
And a cut valve 65 between the primary master cylinder M1 and the wheel brakes BFL, BFR; BRL, BRR in accordance with an increase in the output hydraulic pressure of the proportional pressure increasing valve V.
Is shut off by

Therefore, the hydraulic pressure output from the proportional pressure increasing valve V in response to the operation of the primary master cylinder M 1 in response to the brake operation input acts on the first input hydraulic pressure chamber 60 and the cut valve 65. Is closed, and the output hydraulic pressure chamber 5 is moved by the working piston 58 advanced by the hydraulic pressure of the first input hydraulic pressure chamber 60.
From 9 the boost hydraulic pressure acts on the wheel brakes BFL, BFR; BRL, BRR.

If it is not possible to obtain a boost hydraulic pressure with the proportional pressure increasing valve V due to malfunction of the hydraulic pressure source 12, etc., the primary master cylinder M1
Output hydraulic pressure of the secondary master cylinders M2F and M2R to the second
The output hydraulic chamber 59 is guided from the input hydraulic chamber 61 to the output hydraulic chamber 59 through the orifice 73, the valve chamber 70 and the valve hole 66, and from the second input hydraulic chamber 61 through the communication hole 75 and the cup seal 76. Output hydraulic chamber 59
Can be applied to the wheel brakes BFL, BFR; BRL, BRR.

Further, the cut valve 65 is connected to the first input hydraulic chamber 6.
It is provided in the working piston 58 so as to shut off between the second input hydraulic chamber 61 and the output hydraulic chamber 59 in response to an increase in the hydraulic pressure of zero. Thereby, the cylinder bodies 55, 5
5 ', that is, the length of the secondary master cylinders M2F and M2R can be reduced.

Further, secondary master cylinders M2F and M2R
A large-diameter hole portion 56a having one end closed,
One end is coaxially connected to the other end of the large-diameter hole portion 56a, and the other end is formed with a small-diameter hole portion 56b closed at the other end. The working piston 58 forms an output hydraulic pressure chamber 59 between the large-diameter hole 56a and the one-end closing portion, and the large-diameter piston 58a slidably fitted to the large-diameter hole 56a. , Small diameter hole 5
The first input hydraulic chamber 60 is formed between the small-diameter piston portion 58b and the small-diameter piston portion 58b slidably fitted in the small-diameter hole portion 56b. It is integrally connected by a connecting shaft portion 58c forming an annular second input hydraulic chamber 61 therebetween.

Therefore, when the working piston 58 moves forward in response to the hydraulic pressure output from the proportional pressure increasing valve V acting on the first input hydraulic chamber 60, the volume of the second input hydraulic chamber 61 increases, and the primary The operation stroke of the brake pedal P for operating the master cylinder M1 can be secured.

Further, a set of a valve spring 72 provided in the cut valve 65 so as to exert a spring force in the valve opening direction, and a return spring 62 for urging the working piston 58 to the side where the volume of the output hydraulic chamber 59 increases. Since the load is set such that the cut valve 65 is closed prior to the movement of the working piston 58 by the hydraulic pressure of the first input hydraulic chamber 60 to the side where the volume of the output hydraulic chamber 59 is reduced, the brake is applied. 1 accompanying operation input
When the hydraulic pressure is output from the proportional booster valve V in response to the operation of the next master cylinder M1, the cut valve 65 is closed first, so that the boosted hydraulic pressure from the proportional booster valve V is used to increase the wheel brakes BFL, BFR; , BRR can be transmitted efficiently.

Further, between the primary master cylinder M1 and the cut valve 65, an orifice 73 for restricting the flow of the brake fluid is provided.
In the early stage of the operation of the primary master cylinder M1 in response to the brake operation input, the wheel brakes BFL, B are transmitted from the primary master cylinder M1 via the cut valve 65.
FR; the brake fluid flowing through BRL and BRR can be suppressed by the orifice 73, and the responsiveness of the proportional booster valve V can be improved by preferentially flowing the brake fluid from the primary master cylinder M1 to the proportional booster valve V. it can.

In particular, since the orifice 73 is provided on the working piston 58, an extra space for disposing the orifice 73 is not required, which can contribute to the downsizing of the entire hydraulic booster.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various design changes can be made without departing from the present invention described in the appended claims. It is possible.

[0065]

As described above, according to the first aspect of the present invention, since the cut valve is provided in the working piston, the length of the cylinder body, that is, the secondary master cylinder can be shortened.

According to the second aspect of the present invention, the operation stroke of the operation member for operating the primary master cylinder can be secured.

Further, according to the third aspect of the invention, the boost valve hydraulic pressure from the proportional pressure increasing valve can be efficiently transmitted to the wheel brakes by closing the cut valve first.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram of a hydraulic booster for a brake.

FIG. 2 is a longitudinal sectional view showing a configuration of a proportional pressure increasing valve and a front secondary master cylinder.

FIG. 3 is a longitudinal sectional view of a rear secondary master cylinder.

FIG. 4 is a brake hydraulic pressure characteristic diagram.

[Explanation of symbols]

 12 ... hydraulic pressure source 55, 55 '... cylinder body 56 ... cylinder hole 56a ... large-diameter hole 56b ... small-diameter hole 58 ... working piston 58a ... large-diameter piston Part 58b: Small-diameter piston part 58c: Connection shaft part 59: Output hydraulic chamber 60: First input hydraulic chamber 61: Second input hydraulic chamber 62: Return spring 65 ... Cut valve 72 ... Valve spring BFL, BFR, BRL, BRR ... Wheel brake M1 ... Primary master cylinder M2F, M2R ... Secondary master cylinder V ... Proportional pressure increasing valve

Claims (3)

[Claims] 1. A primary master cylinder (M1) for outputting a hydraulic pressure in response to a brake operation input, and a hydraulic pressure higher than an output hydraulic pressure of the primary master cylinder (M1) regardless of the presence or absence of a brake operation. A hydraulic pressure source (12) capable of outputting, a proportional pressure increasing valve (V) that draws a hydraulic pressure proportional to the output hydraulic pressure of the primary master cylinder (M1) from the hydraulic pressure source (12), and outputs the hydraulic pressure. By outputting a hydraulic pressure according to the output hydraulic pressure of the pressure valve (V), the wheel brakes (BFL, BFR, B
RL, BRR) connected to the secondary master cylinder (M2
F, M2R) and a cut valve (B) that cuts off between the primary master cylinder (M1) and the wheel brakes (BFL, BFR, BRL, BRR) as the output hydraulic pressure of the proportional pressure increase valve (V) increases. 65), wherein the secondary master cylinder (M2F, M2
R) includes a cylinder body (55, 55 ') having a cylinder hole (56) closed at both ends and the wheel brake (B).
FL, BFR, BRL, BRR), the output hydraulic chamber (59) connected to the proportional pressure-intensifying valve (V), and the first input hydraulic chamber (60) connected to both ends. An annular second input hydraulic chamber (61) connected to the cylinder (M1) is formed between the second input hydraulic chamber (61) and the inner periphery of the cylinder hole (56), and is slidably fitted in the cylinder hole (56). Working piston (58) and first input hydraulic chamber (60)
And a return spring (62) for urging the working piston (58) toward the side to reduce the volume of the valve. The cut valve (65) is adapted to increase the hydraulic pressure of the first input hydraulic chamber (60). A hydraulic booster for a brake, wherein the hydraulic booster is provided in the working piston (58) so as to shut off the space between the second input hydraulic chamber (61) and the output hydraulic chamber (59). 2. The cylinder hole (56) has a large-diameter hole (56a) closed at one end, and one end coaxially connected to the other end of the large-diameter hole (56a) and the other end closed. The working piston (58) is formed stepwise with a small-diameter hole (56b), and the output hydraulic chamber (59) is provided between the working piston (58) and the one-end closing portion of the large-diameter hole (56a). The large-diameter piston portion (5) formed and slidably fitted in the large-diameter hole portion (56a).
8a) and the small-diameter piston slidably fitted in the small-diameter hole (56b) by forming the first input hydraulic chamber (60) between the small-diameter hole (56b) and the other end closing portion. Department (5
8b) is a connecting shaft portion (58) forming an annular second input hydraulic chamber (61) between itself and the inner surface of the cylinder hole (56).
2. The method as claimed in claim 1, wherein the parts are integrally connected at c).
The hydraulic pressure booster for a brake according to the above. The cut valve (65) includes a valve spring (72) that exerts a spring force in a valve opening direction against a force in a valve closing direction due to hydraulic pressure of a first input hydraulic chamber (60). The set load of the return spring (62) and the valve spring (72) is
The cut valve (65) is closed prior to the movement of the working piston (58) by the hydraulic pressure of the first input hydraulic chamber (60) to the side of reducing the volume of the output hydraulic chamber (59). 3. The booster hydraulic device for a brake according to claim 1, wherein the hydraulic booster is set to: