JPH01111561A - Hydraulic type booster unit - Google Patents

Abstract

PURPOSE:To improve controllability by letting both a spring load energizing a booster piston backward and the pressure receiving area of the booster piston facing an output hydraulic chamber at the backside of the booster piston be regulated with ease, and enabling the stroke of said piston to be sufficiently secured. CONSTITUTION:A booster piston 52 energized backward by a spring 61 is coupled with the booster cylinder 28 of a hydraulic booster B. An inlet valve 72 is arranged between an output hydraulic chamber 59 formed by the aforesaid piston 52 and an input hydraulic chamber 57. This inlet value 72 is opened in response to the advancing operation of the booster piston 52 interlocked with an actuating member 1. In addition, an outlet valve 73 is arranged between the output hydraulic chamber 59 and an outlet chamber 68. Furthermore, the operating piston 4 of a master cylinder M is coupled with a cylinder body 8 formed monolithically with a cylinder main body 2, and a valve piston 65 the tip end of which is plunged into a booster chamber 24 facing the back face of the operating piston 4 is coupled with the booster piston 52. An oil feeding passage 77 communicating both the chambers 57 and 24 each other by opening the inlet valve 72 is cut through the aforesaid piston 65.

Description

DETAILED DESCRIPTION OF THE INVENTION A1 Object of the Invention (1) Industrial Application Field The present invention relates to a hydraulic booster, and particularly to a hydraulic booster used in a vehicle brake system.

(2) Conventional Technology Conventionally, such hydraulic boosters have been designed such that the stroke of the operating member is small enough to open and close a hydraulic control valve, as disclosed in, for example, Japanese Patent Publication No. 53-39953. A so-called strokeless type and a stroke type in which the stroke of the operating member is the same as that of the working piston in the master cylinder are known.

(3) Problems to be Solved by the Invention However, in the above-mentioned strokeless type, the stroke of the operating member is small and the amount of operation does not correspond to the amount of operation, so there is a window of incongruity. Furthermore, since the stroke increases when the oil pressure fails, it becomes difficult to layout the seat of the oil pressure control valve. Furthermore, in stroke type devices, the stroke of the operating member is too large, and in order to shorten the stroke, the inner diameter of the cylinder body in the master cylinder may be increased, but this will result in poor effectiveness in the event of oil pressure failure.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a hydraulic booster that can obtain an arbitrary stroke.

B8 Structure of the Invention (1) Means for Solving the Problems According to the present invention, a booster cylinder is coupled to the rear end of the cylinder body of the master cylinder, and is slidably fitted into a piston guide provided on the booster cylinder. Between the output hydraulic pressure chamber, which is formed facing the back of the booster piston that is pressed together and is biased rearward by a spring, and the input hydraulic chamber, which communicates with the hydraulic pressure supply source, there is a hydraulic chamber connected to the operating member that slides onto the booster piston. An inlet valve that opens in response to forward movement of a movably fitted valve piston with respect to a booster piston is interposed, and a booster piston of the valve piston is provided between the output hydraulic chamber and an outlet chamber communicating with the oil tank. An outlet valve is provided which closes in response to forward movement of the master cylinder, and the operating piston in the master cylinder is slidably fitted into a cylindrical body fixed to the cylinder body, and is capable of coming into contact with the tip of the booster piston. A boost chamber facing the rear side of the actuating piston is formed between the guide member slidably fitted to the rear of the cylinder body and the actuating piston, and the tip of the valve piston is
The valve piston is inserted into the boost chamber by penetrating the guide member in an oil-tight and movable manner, and the valve piston has an oil supply passage that communicates between the input hydraulic pressure chamber and the boost chamber in response to opening of the inlet valve. will be established.

(2) Effect According to the above configuration, at the initial stage when the valve piston is pressed forward by the operating member, the inlet valve opens after the outlet valve closes, and hydraulic pressure is supplied to the boost chamber. The operating piston moves forward and output hydraulic pressure is generated in the master cylinder, but the booster piston moves forward against the spring force due to the hydraulic pressure supplied to the output hydraulic chamber, and until the booster piston comes into contact with the guide member, The booster piston and the valve piston move relative to each other while taking turns, and during this period, the working piston moves forward in accordance with the stroke of the operating member, so that the output oil pressure of the master cylinder increases in accordance with the stroke of the operating member. After the booster piston comes into contact with the guide member, the inlet valve remains open.
Therefore, the oil pressure continues to be supplied to the boost chamber, and the output oil pressure increases rapidly. Moreover, since the guide member is slidably fitted into the cylinder, even if the guide member is relatively long, it is possible to ensure a sufficient stroke of the booster piston in the event of oil pressure failure, and to guide the valve piston. can be carried out satisfactorily.

(3) Embodiment Below, an embodiment of the present invention will be explained with reference to the drawings. First, in FIG. A hydraulic booster B is connected to the rear part, and a bushing rod 1 as an operating member linked and connected to the brake pedal P moves forward in response to the depression operation of the brake pedal P, thereby boosting the hydraulic booster B. This occurs, and braking oil pressure is generated in the master cylinder M accordingly.

The master cylinder M is a tandem type master cylinder, and the cylinder body 2 has a front working piston (
(not shown) and a rear working piston 4 forming the other hydraulic chamber 3 between the front working piston and the rear working piston 4 are slidably fitted, and the front end wall of the cylinder body 2 and the front working piston A spring (not shown) for biasing the working piston rearward is interposed between the working piston and the working piston 4, and a spring (not shown) is interposed between the working piston 4 on the front side and the working piston 4 on the rear side. A spring (not shown) is interposed to bias it toward the side. Therefore, by pressing the rear working piston 4 forward, the volumes of the front hydraulic chamber and the rear hydraulic chamber 3 are contracted, and braking hydraulic pressure is output from these hydraulic chambers 3.

A large-diameter fitting hole 6 is provided at the rear end of the cylinder body 2 through a step 5, and the cylinder body has a flange 7 on the outer surface of the intermediate portion that comes into contact with the step 5. 8 is fitted to the rear end of the cylinder body 2 via a seal member 9. This cylinder 8
The rear part of the cylinder body 2 projects rearward from the cylinder body 2, and the rear end of the cylinder body 8 has a regulating collar 10 that extends radially inward.
are provided all around. The actuating piston 4 is provided with a pair of lands 12 and 13 spaced apart in the axial direction with an annular groove 11 interposed between them.The front land 12 has a cup that slides into contact with the inner surface of the cylinder body 2. Seal 14 is fitted. Further, the land 13 on the rear side is inserted into the cylindrical body 8, and a cup seal 15 that comes into sliding contact with the inner surface of the cylindrical body 8 is fitted into this land 13. As a result, an annular replenishment oil chamber 16 is defined between both lands 12 and 13. Moreover, the land 12 and the cup seal 14 on the front side are configured to allow the flow of hydraulic oil from the replenishment oil chamber 6 to the hydraulic chamber 3 when the pressure in the hydraulic chamber 3 is lower than that in the replenishment oil chamber 16. 2 and the cylinder 8,
A replenishment oil passage 17 is provided that allows the replenishment oil chamber 16 to communicate with an oil tank (not shown).

The actuating piston 4 has an elongated hole 18 extending along one diameter line in a portion extending between the lands 12 and 13, and both ends of a stopper pin 19 passing through the elongated hole 18 are fixed to the cylinder body 8. Ru. Further, a valve mechanism 20 that is driven to open and close by a stopper pin 19 is disposed at the front of the operating piston 4 in order to communicate and disconnect between the hydraulic chamber 3 and the replenishment oil chamber 16, and this valve mechanism 20 is operated. When the piston 4 returns to its retracting limit, that is, when the rear end of the working piston 4 comes into contact with the guide member 21 fitted to the rear of the cylinder 8, it is pressed by the stopper pin 19 to open the valve.

The guide member 21 is basically formed in a cylindrical shape, with a flange 22 at the front end that abuts the regulating flange 0 from the inside, and the rear end extends from the rear end of the cylindrical body 8 to the rear side. The cylindrical body 8 is made to protrude.
fitted inside. A seal member 23 that contacts the inner surface of the cylindrical body 8 is fitted onto the outer surface of the flange portion 22 . As a result, a boost chamber 24 is defined within the cylinder body 8 between the actuating piston 4 and the guide member 21, and the back side of the actuating piston 4 faces.
The actuating piston 4 moves forward in response to an increase in the oil pressure in its boost chamber 24.

At the rear end of the cylinder body 2, a connecting cylinder part 25 that concentrically surrounds the cylinder body 8 forms a step part 26 between the fitting hole part 6 and protrudes. , an annular clamping member 27 integrally having a cylindrical pressing part 27a that protrudes into the fitting hole 6 and clamps the collar part 7 of the cylinder 8 between it and the step part 5 is brought into contact.

Hydraulic booster B includes a booster cylinder 28,
The front part of this booster cylinder 28 has the connecting cylinder part 2.
A connecting cylindrical portion 29 into which the connector 5 can be fitted is provided in a protruding manner, and a sealing member 30 that contacts the inner surface of the connecting cylindrical portion 29 is fitted onto the outer surface of the connecting cylindrical portion 25 . Further, a flange 31 is provided at the tip of the connecting cylinder portion 29, and this flange 31 and
A flange 32 provided at the base end of the connecting cylinder portion 25 in the cylinder body 2 is connected by a plurality of bolts 33, thereby connecting the master cylinder M and the hydraulic booster B.

A cylinder hole 34 is bored coaxially with the actuating piston 4 in the booster cylinder 2, and a stepped portion 35 facing the master cylinder M side is provided between the cylinder hole 34 and the connecting cylinder portion 29. provided. A rear end of a cylindrical guide cylinder 37 having a front end abutting against the holding member 27 and a seal member 36 on the outer surface contacting the inner surface of the connecting cylinder part 29 is abutted on the step part 35 . Therefore, in a state where the cylinder body 2 and the booster cylinder 28 are connected to each other, the clamping member 27 and the guide cylinder 37 are in contact with each other in the axial direction, while the cylinder body 2 and the booster cylinder 28 are connected to each other.
The cylinder body 8 is also fixed to the cylinder body 2 accordingly.

The inner diameter D1 of the guide cylinder 37 is the inner diameter D2 of the cylinder hole 34.
(DI<02), and a basically cylindrical piston guide 38 is slidably fitted into the guide cylinder 37 and the booster cylinder 28. This piston guide has a land 39 at the front end that is slidably fitted into the guide cylinder 37, and a cylinder hole 34.
The rear end has a land 40 that is slidably fitted into the guide cylinder 37. A cup seal 41 that slides on the inner surface of the guide cylinder 37 is fitted on the land 39, and a cup seal 41 that slides on the inner surface of the cylinder hole 34 is fitted on the land 40. A sliding cup seal 42 is fitted.

As a result, an annular hydraulic chamber 43 is formed between the guide cylinder 37 and the booster cylinder 28 and the piston guide 3. On the other hand, an annular oil chamber 44 is formed between the booster cylinder 2 and the guide cylinder 37;
4 is a notch provided at the rear end of the guide cylinder 37 and a stepped portion 3
It communicates with the annular hydraulic chamber 43 via an oil passage 45 between the hydraulic pressure chamber 5 and the annular hydraulic chamber 43. Further, the booster cylinder 28 is provided with an inlet oil passage 46 that communicates a hydraulic pressure supply source (not shown) with the oil chamber 44, and the annular hydraulic chamber 43 is constantly supplied with hydraulic pressure from the hydraulic pressure supply source.

Moreover, as mentioned above, since Di<D2, the piston guide 38 is pressed toward the rear side by the hydraulic pressure in the annular hydraulic chamber 43, and unless there is a hydraulic failure, the piston guide 38 will move behind the booster cylinder 28. The land 40 is at the retracting limit position where it comes into contact with a regulating flange 47 provided at the end. Furthermore, there is a space between the front end of the piston guide 38 and the clamping member 27 pressed against the rear end of the cylinder body 2 in the master cylinder M, so that when oil pressure failure occurs, the piston guide 38 is directed toward the backward limit position. Return spring 4 for pressing
8 will be reduced.

The piston guide 38 includes a first cylinder hole 50 having an inner diameter D3, and an inner diameter D4 (D3) coaxially connected to the rear end of the cylinder hole 50 and smaller than the inner diameter D3.
>D4), and a booster piston 52 is slidably fitted into the first and second cylinder holes 50, 51. That is, the booster piston 52 includes a large diameter portion 52a that is slidably fitted into the first cylinder hole 50, and a large diameter portion 52a that is connected to the rear end of the large diameter portion 52a and is slidable into the second cylinder hole 51. It is basically formed in a cylindrical shape and has a small diameter portion 52b that fits into the small diameter portion 52b. Also, the large diameter portion 52 of the booster piston 52
a is provided with an annular groove 53, and this large diameter portion 52a
Cup seals 54 and 55 that are in sliding contact with the inner surface of the first cylinder hole 50 are fitted to both end edges of the annular groove 53 along the axial direction of the second cylinder hole 5 in the piston guide 38 .
A cup seal 56 that comes into sliding contact with the small diameter portion 52b of the booster piston piston 52 is fitted into the booster piston 1.

An annular input hydraulic pressure chamber 57 is defined by an annular groove 53 between the piston guide 38 and the large-diameter portion 52 a of the booster piston 52 . The path 58 is the piston guide 3
8. Further, an annular output hydraulic pressure chamber 59 is defined between the piston guide 38 and the booster piston 52 and faces the front surface of the large diameter portion 52a of the booster piston 52.

At the rear end of the booster piston 52 is a cylindrical receiver member 60.
A stroke adjustment spring 61 for urging the booster piston 52 rearward is compressed between the member 60 and the rear end of the piston guide 38 . Furthermore, a regulating collar 62 projecting outward in the radial direction is integrally provided at the front part of the booster piston 52 so as to be able to come into contact with the front end of the piston guide 38, thereby allowing the booster piston 52 to retreat with respect to the piston guide 38. The limits are specified.

A small diameter cylinder hole 63 on the front side and a large diameter cylinder hole 64 on the rear side are coaxially bored in the booster piston 52. A valve piston 65 connected to the bushing rod 1 is slidably fitted. That is, the valve piston 6
5 has a small diameter portion 65a that is slidably fitted into the small diameter hole 63 via a sealing member 66, and a large diameter portion 65b that is slidably fitted into the large diameter hole 64, which are coaxially connected. The bushing rod 1 is coaxially connected to the rear end of the large diameter portion 65b. Further, the tip of the small diameter portion 65a of the valve piston 65 is
It slidably passes through the guide member 21 and enters the boost chamber 24. Furthermore, a seal member 67 is fitted onto the inner surface of the guide member 21 so as to be in sliding contact with the outer surface of the small diameter portion 65a.

An outlet chamber 68 is defined between the clamping member 27 and the cylindrical body 8 of the master cylinder M and the front end of the booster piston 52, the outer periphery of which is defined by the guide cylindrical body 37. Further, an annular oil passage 69 is defined between the connecting cylinder part 25.29 and the guide cylinder 37, and this annular oil passage 69 connects to the outlet chamber 6 through a communication hole 70 bored in the connecting cylinder part 25. It will be communicated daily. Further, the connecting cylinder portion 29 has an outlet oil passage 7 communicating with the annular oil passage 69.
1 is bored, and this outlet oil passage 71 is connected to an oil tank (not shown). The outlet chamber 68 therefore communicates with the oil tank.

An inlet valve 72 that communicates and blocks communication between the input hydraulic chamber 57 and the output hydraulic chamber 59 and an outlet valve 73 that communicates and blocks communication between the output hydraulic chamber 59 and the outlet chamber 68 are connected to the booster piston 38 and the valve piston 65. It consists of

The inlet valve 72 is composed of an annular recess 74 provided on the outer surface of the intermediate portion of the valve piston 65, and an inlet valve hole 75 bored in the booster piston 52 and communicating with the input hydraulic pressure chamber 57. The annular recess 74 is provided relatively long in the axial direction of the valve piston 65, and the inlet valve hole 75 is bored along the radial direction of the booster piston 52. In addition, a communication hole 76 is formed in the booster piston 52 so that the annular recess 74 is always communicated with the output hydraulic pressure chamber 59 regardless of the relative movement of the valve piston 65 in the axial direction.

The inlet valve 72 opens when the inlet valve hole 75 connects with the annular recess 74 , and when the valve piston 65 is at the retracting limit with respect to the booster piston 52 , the inlet valve hole 75 connects with the annular recess 74 . The positions of the inlet valve hole 75 and the annular recess 74 are set so that the valve is in a closed state when the valve is in a forward position.

Further, an oil supply passage 77 is bored in the valve piston 65 along the axial direction from the intermediate portion to the tip thereof, and the rear end of this oil supply passage 77 is constantly communicated with the annular recess 74 .

Therefore, when the inlet valve 72 is open, hydraulic pressure is also supplied to the oil supply passage 77, and the front end of this oil supply passage 77 communicates with the boost chamber 24, so when the inlet valve 72 is opened, the oil pressure is also supplied to the boost chamber 24. Hydraulic pressure will be supplied.

The outlet valve 73 has a first outlet valve hole 79 formed in the booster piston 52 and communicating with an annular chamber 78 formed between the piston guide 38 and the front end of the booster piston 52 to communicate with the outlet chamber 68 . , and a second outlet valve hole 80 that is bored in the valve piston 65 and communicates with the oil supply passage 77, and both outlet valve holes 79 and 80 are connected to the booster piston 52 at mutually corresponding positions. and valve piston 65
The hole is drilled along the radial direction of the hole. In such an outlet valve 73, when the valve piston 6.5 is at the retraction limit with respect to the booster piston 52, the first and second outlet valve holes 79.8
0 communicate with each other and the valve is slightly open,
When the forward movement of the valve piston 65 relative to the booster piston 52 starts, the inlet valve 72 closes before it opens.

Furthermore, when the outlet valve 73 is open, the oil supply passage 77 communicates with the outlet chamber 68, and the hydraulic pressure in the boost chamber 24 and the output hydraulic chamber 59 is released.

The receiver screwed onto the rear end of the booster piston 52 is a member 60.
The valve piston 65 is in contact with the rear end of the valve piston 65.
A circlip 81 is fitted to restrict the retraction limit of the circlip. Further, a spring 82 is compressed between the member 60 and the rear end of the valve piston 65, and the spring 82 urges the valve piston 65 backward.

Next, the operation of this embodiment will be explained. When the brake pedal P is not actuated, the valve piston 65 is held at the backward limit with respect to the booster piston 52 by the spring force of the spring 82, and the booster piston 52 is adjusted in stroke. A spring 61 holds the piston guide 38 at its retracting limit.

Furthermore, the piston guide 38 is at the retracting limit where the land 40 at the rear end abuts against the regulating flange 47 of the booster cylinder 2 due to the hydraulic pressure supplied to the annular hydraulic chamber 43.

In this state, the inlet valve 72 is closed and the outlet valve 7 is closed.
Since the valve 3 is open, the output hydraulic pressure chamber 59 and the boost chamber 24 are at atmospheric pressure.

When the brake pedal P is depressed to brake the automobile in this state, the valve piston 65 is pushed forward from the brake pedal P via the bushing rod 1, and the outlet valve 73 is first closed, and then the inlet valve 72 is opened. speak. Therefore, hydraulic pressure is introduced into the boost chamber 24 from the input hydraulic pressure chamber 57 via the oil supply path 77, and the actuating piston 4 receives the hydraulic pressure on its back surface and moves forward, and the boosting operation of the master cylinder M is started.

By the way, when the inlet valve 72 is opened, hydraulic pressure is supplied to the boost chamber 24 as described above, and hydraulic pressure is also supplied to the output hydraulic chamber 59, and the booster piston 52 also receives hydraulic pressure on its back surface, thereby opening the valve. Since it moves forward relative to the piston 65, the inlet valve 72 is closed and the outlet valve 73 is opened. Therefore, before the artificial valve 72 is closed and the outlet valve 73 is opened, the boost chamber 2
The working piston 4 moves forward due to the hydraulic pressure applied to the second
The output oil pressure of the master cylinder M increases rapidly as shown by the characteristic line Pa P+ shown by the solid line in the figure. As a result, play in each part up to the brake terminal is immediately eliminated.

After the output oil pressure reaches P, the valve piston 65 moves forward in response to the depression of the brake pedal P, so that the valve piston 65 moves forward relative to the booster piston 52, and the booster piston 52 moves forward relative to the valve piston 65. is repeated alternately, and the opening and closing of the inlet valve 72 and the outlet valve 73 are alternately repeated. Therefore, the oil pressure of the boost chamber 24, that is, the amount of forward movement of the working piston 4 also changes according to the amount of forward movement of the valve piston 65. and increase,
As shown by the characteristic line P+Pt, the output oil pressure of the master cylinder M increases according to the stroke.

After the tip of the booster piston 52 comes into contact with the guide member 21 due to its forward movement, the forward movement of the booster piston 52 is blocked. Therefore, from then on, the valve piston 65 is in a position in front of the booster piston 65, and the inlet valve 72 continues to be opened, so that the oil pressure in the boost chamber 24 rapidly increases, and the output oil pressure also rises rapidly.

Brake pedal P to release the operation of master cylinder M
When the valve piston 65 is released, the spring force of the spring 82 causes the valve piston 65 to
First, the inlet valve 72 is closed, and then the outlet valve 73 is opened. As a result, the hydraulic pressure in the boost chamber 24 is released, and the working piston 4 retreats to its retraction limit, and the output hydraulic pressure chamber 5
9 is released, the booster piston 52 quickly retreats due to the spring force of the stroke adjustment spring 61 until its regulating collar 62 comes into contact with the front end of the piston guide 38.

In such a hydraulic booster, the characteristic line P+P in FIG.
z is the hydraulic pressure that presses the booster piston 52 forward due to the fact that the inner diameter D3 is larger than the inner diameter D4 (D3>04) and the stroke adjustment spring 61 that pushes the booster piston 52 forward due to the hydraulic pressure of the output hydraulic chamber 59. 52 to the rear side, and the range in which the output oil pressure of the master cylinder M corresponds to the stroke is determined by the inner diameter D3.52. D4 and stroke adjustment spring 6
It can be arbitrarily set by adjusting the load of 1. Therefore, compared to the strokeless type shown by the chain line A in Fig. 2, it is possible to make the operation amount correspond to the actuation amount within an arbitrary range and eliminate the sense of discomfort, and the stroke type shown by I1%B in Fig. 2 The stroke can be made shorter compared to the previous one.

Let us also assume that a hydraulic pressure failure occurs in this hydraulic booster. In this case, since the hydraulic pressure in the annular hydraulic chamber 43 decreases, the piston guide 38 is held at the retracting limit by the return spring 48. Therefore, when the brake pedal P is depressed to perform a braking operation, the valve piston 65 moves forward while contracting the spring 82, and further moves the booster piston 52 while contracting the stroke adjustment spring 61 and the return spring 48.
and the piston guide 38 moves forward, and the valve piston 6
5 is in contact with the rear end of the working piston 4 and
Press and move it forward. As a result, an output hydraulic pressure is generated from the master cylinder M. The forward movement of the valve piston 65, the booster piston 52, and the piston guide on the third day is such that the tip of the booster piston 52 that is in contact with the guide member 21 touches the rear end of the cylinder 8 while pushing the guide member 21 into the cylinder 8. This continues until they come in contact with each other, thereby making it possible to obtain sufficient output oil pressure from the master cylinder M, and even in the event of oil pressure failure, it becomes possible to obtain sufficient braking oil pressure. Moreover, since the guide member 21 is slidable within the cylinder 8, the guide member 21 can be set relatively long while ensuring the stroke of the valve piston 65 in the event of oil pressure failure. By making the length of the valve piston 21 relatively long, the valve piston 65 can be sufficiently guided.

C0 Effects of the Invention As described above, according to the present invention, the booster cylinder is coupled to the rear end of the cylinder body of the master cylinder, and is slidably fitted into the piston guide provided on the booster cylinder, and is fitted on the rear side. An output hydraulic chamber formed facing the rear side of the spring-biased booster piston and an input hydraulic chamber communicating with a hydraulic pressure supply source are connected to an operating member and slidably fitted to the booster piston. An inlet valve that opens in response to the forward movement of the valve piston relative to the booster piston is interposed, and an inlet valve that opens in response to the forward movement of the valve piston relative to the booster piston is provided between the output hydraulic pressure chamber and an outlet chamber communicating with the oil tank. An operating piston in the master cylinder is slidably fitted into a cylindrical body fixed to the cylinder body, and is fitted into the rear part of the cylindrical body so as to be able to come into contact with the tip of the booster piston. A boost chamber facing the rear side of the actuating piston is formed between the combined guide member and the actuating piston, and the tip of the valve piston is
The valve piston is inserted into the boost chamber by penetrating the guide member in an oil-tight and movable manner, and the valve piston has an oil supply passage that communicates between the input hydraulic pressure chamber and the boost chamber in response to opening of the inlet valve. By adjusting the load of the spring that biases the booster piston rearward and the pressure-receiving area of the booster piston facing the output hydraulic pressure chamber, the range in which the stroke of the operating member corresponds to the output hydraulic pressure can be arbitrarily adjusted. It is possible to set the stroke of the operating member to be in the intermediate range between the conventional strokeless type and stroke type, thereby resolving the discomfort.

Moreover, since the guide member is slidably fitted to the cylindrical body,
The stroke of the operating member can be made relatively large by sliding the guide member in accordance with the movement of the booster piston when oil pressure fails, and the length of the guide member is made relatively large to sufficiently guide the valve piston. becomes possible.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a longitudinal sectional side view, and FIG. 2 is a characteristic diagram. ■... Bush rod as an operating member, 2... Cylinder body, 4... Operating piston, 8... Cylindrical body, 2
1... Guide member, 24... Boost chamber, 28...
・Booster cylinder, 38...Piston guide, 52
... Booster piston, 57 ... Input hydraulic chamber, 59
...Output hydraulic chamber, 65...Valve piston, 68...
Outlet chamber, 72... Inlet valve, 73... Outlet valve, 77.
...Oil supply path, M... Master cylinder patent applicant Nissin Kogyo Co., Ltd. Honda Motor Co., Ltd.

Claims (1)

[Claims] A booster cylinder is coupled to the rear end of the cylinder body of the master cylinder, and is slidably fitted into a piston guide provided on the booster cylinder and is formed facing the rear surface of the booster piston that is biased rearward by a spring. A valve piston connected to the operating member and slidably fitted to the booster piston is connected between the output hydraulic chamber and the input hydraulic chamber communicating with the hydraulic pressure supply source. An inlet valve is interposed between the output hydraulic pressure chamber and an outlet chamber communicating with the oil tank. is a guide member that is slidably fitted to a cylindrical body fixed to the cylinder body, and that is slidably fitted to the rear of the cylindrical body so as to be able to come into contact with the tip of the booster piston, and an operating piston. A boost chamber facing the rear side of the actuating piston is formed therebetween, and the tip of the valve piston is inserted into the boost chamber by penetrating the guide member in an oil-tight and movable manner,
A hydraulic booster characterized in that the valve piston is provided with an oil supply passage that communicates between an input hydraulic chamber and a boost chamber in response to opening of the inlet valve.