JP2516784B2 - Hydraulic booster - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Objects of the Invention (1) Field of the Invention The present invention relates to a hydraulic booster, and more particularly to a hydraulic booster used for a vehicle brake device.

(2) Conventional Technology Conventionally, such a hydraulic booster has only a small stroke of an operating member for opening and closing a hydraulic control valve as disclosed in 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 strokeless type, there is a feeling of strangeness because the stroke of the operation member is small and the operation amount does not correspond to the operation amount. In addition, since the stroke increases when the hydraulic pressure fails, it becomes difficult to lay out the seat of the hydraulic control valve. Further, in the case of the stroke type, the stroke of the operating member is too large, and the inner diameter of the cylinder body in the master cylinder may be increased in order to shorten the stroke.

The present invention has been made in view of such circumstances,
It is an object of the present invention to provide a hydraulic booster capable of obtaining an arbitrary stroke.

B. Configuration of the Invention (1) Means for Solving 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 made slidable on a piston guide provided on the booster cylinder. The booster piston is connected between the output hydraulic chamber formed facing the rear surface of the booster piston that is fitted and spring-biased to the rear side, and the input hydraulic chamber that communicates with the hydraulic pressure supply source, in series with the operating member. An inlet valve that opens in response to the forward movement of the slidably fitted valve piston with respect to the booster piston is provided, and between the output hydraulic chamber and the outlet chamber that communicates with the oil tank,
An outlet valve that closes in response to the forward movement of the valve piston with respect to the booster piston is provided, and the working piston in the master cylinder is slidably fitted to a cylinder body fixed to the cylinder body. A boost chamber facing the back surface of the working piston is formed between the working piston and the guide member slidably fitted to the rear portion of the cylindrical body so as to be able to contact the front end, and the tip of the valve piston is
The guide member is oil-tightly and movably pierced into the boost chamber, and the valve piston is provided with an oil supply passage communicating between the input hydraulic chamber and the boost chamber in response to opening of the inlet valve. Set up.

(2) Operation According to the above configuration, at the initial stage when the valve piston is pushed forward by the operating member, the inlet valve is opened after the outlet valve is closed, and the hydraulic pressure is supplied to the boost chamber. The working piston moves forward and the output hydraulic pressure is generated in the master cylinder, but by the supply of hydraulic pressure to the output hydraulic chamber, the booster piston moves forward against the spring force, and before the booster piston contacts the guide member, The booster piston and the valve piston move relative to each other while alternating with each other, and during this period, the working piston moves forward in accordance with the stroke of the operating member, so that the output hydraulic pressure of the master cylinder increases in accordance with the stroke of the operating member. Then, after the booster piston comes into contact with the guide member, the inlet valve remains open, and therefore the hydraulic pressure remains supplied to the boost chamber, so that the output hydraulic pressure rapidly increases. Moreover, since the guide member is slidably fitted to the tubular body, even if the guide member is relatively long, the stroke of the booster piston at the time of hydraulic pressure failure can be sufficiently secured, and the guide of the valve piston can be maintained. Can be fully performed.

(3) Embodiment Hereinafter, one embodiment of the present invention will be described with reference to the drawings. First, in FIG. 1, this hydraulic booster is for a brake device mounted on an automobile, and includes a master cylinder M. A hydraulic booster B is connected to the rear part, and the push rod 1 as an operating member that is interlocked with and linked to the brake pedal P moves forward in response to the depression operation of the brake pedal P, thereby boosting the hydraulic booster B. Occurs, and braking hydraulic pressure is generated in the master cylinder M accordingly.

The master cylinder M is a tandem type master cylinder, and in the cylinder body 2, a front working piston (not shown) that forms one hydraulic chamber between the cylinder body 2 and the front end wall of the cylinder body 2, and the front thereof. A rear side working piston 4 that forms the other hydraulic chamber 3 is slidably fitted between the side working piston and the side working piston, and the front side working piston and the front side working piston of the cylinder body 2 are connected to each other. A spring (not shown) for biasing the working piston to the rear side is provided, and the working piston 4 is provided between the front side working piston and the rear side working piston 4.
A spring (not shown) for biasing the rearward side is interposed. Therefore, by pushing the working piston 4 on the rear side to the front side, the volumes of the front side hydraulic chamber and the rear side hydraulic chamber 3 contract, and the braking hydraulic pressure is output from these hydraulic chambers 3.

A large-diameter fitting hole portion 6 is provided at the rear end of the cylinder body 2 via a step portion 5, and a collar portion 7 that abuts on the step portion 5.
The cylindrical body 8 having the outer surface of the middle portion is the cylinder body 2
The rear end portion is fitted with a seal member 9 in between. The rear portion of the tubular body 8 is projected rearward from the cylinder body 2, and the rear end of the tubular body 8 has a restricting flange 10 that extends radially inward.
Is provided all around. The working piston 4 is provided with a pair of lands 12 and 13 with an annular groove 11 interposed between them at a distance in the axial direction, and the land 12 on the front side slidably contacts the inner surface of the cylinder body 2. The seal 14 is fitted. The land 13 on the rear side is to be inserted into the cylindrical body 8, and the land 13 is fitted with a cup seal 15 that is in sliding contact with the inner surface of the cylindrical body 8. As a result, both lands 12,1
An annular supply oil chamber 16 is defined between the three. Moreover, the land 12 and the cup seal 14 on the front side are arranged so that when the hydraulic chamber 3 is depressurized more than the replenishing oil chamber 16, the replenishing oil chamber 16 moves to the hydraulic chamber 3
The cylinder body 2 and the cylinder body 8 are provided with a replenishment oil passage 17 for communicating the replenishment oil chamber 16 with an oil tank (not shown).

The working piston 4 is formed with a long hole 18 along a diameter line at a portion extending between the lands 12 and 13, and both ends of a stopper pin 19 penetrating the long hole 18 are fixed to the cylindrical body 8. It In addition, a stopper pin 19 is provided at the front of the working piston 4.
A valve mechanism 20 that is driven to open and close by is provided so as to communicate and block between the hydraulic chamber 3 and the replenishment oil chamber 16, and this valve mechanism 20 is provided when the working piston 4 returns to the backward limit, that is, the working piston. When the rear end of No. 4 comes into contact with the guide member 21 fitted to the rear part of the tubular body 8, the stopper pin 19 presses it to open the valve.

The guide member 21 is a collar portion that abuts the regulating collar 10 from the inside.
It has a front end 22 and is basically formed in a cylindrical shape, and is fitted into the cylindrical body 8 with its rear end portion protruding rearward from the rear end of the cylindrical body 8. A seal member 23 that contacts the inner surface of the tubular body 8 is fitted on the outer surface of the collar portion 22. As a result, a boost chamber 24 facing the back surface of the working piston 4 is defined between the working piston 4 and the guide member 21 in the cylindrical body 8, and the working piston 4 moves forward in accordance with an increase in the hydraulic pressure of the boost chamber 24. .

At the rear end of the cylinder body 2, a connecting cylinder portion 25 concentrically surrounding the cylinder body 8 is provided so as to project from the fitting hole portion 6 by forming a step portion 26. An annular clamping member 27 integrally having a cylindrical pressing portion 27a that protrudes into the fitting hole portion 6 and clamps the flange portion 7 of the cylindrical body 8 between the stepped portion 5 and the cylindrical pressing portion 27a is abutted.

The hydraulic booster B has a booster cylinder 28,
A connecting cylinder portion 29 into which the connecting cylinder portion 25 can be fitted is projectingly provided at a front portion of the booster cylinder 28, and an outer surface of the connecting cylinder portion 25 is in contact with an inner surface of the connecting cylinder portion 29. 30 is fitted. Further, a flange 31 is provided at the tip of the connecting tube portion 29, and this flange 31 and a flange 32 provided at the base end of the connecting tube portion 25 in the cylinder body 2 are joined by a plurality of bolts 33, Thus, the master cylinder M and the hydraulic booster B are connected.

A cylinder hole 34 is formed in the booster cylinder 28 coaxially with the working piston 4.
A step portion 35 facing the master cylinder M side is provided between and the connecting cylinder portion 29. A rear end of a cylindrical guide cylinder 37 having a seal member 36 that contacts the inner surface of the connecting cylinder 29 on the outer surface thereof contacts the front end of the stepped portion 35 on the sandwiching member 27. Therefore, with the cylinder body 2 and the booster cylinder 28 coupled to each other, the clamping member 27 and the guide cylinder 37 are in contact with each other in the axial direction, and the cylinder body 2
It is also sandwiched between the booster cylinders 28, and the cylinder body 8 is also fixed to the cylinder body 2 accordingly.

The inner diameter D1 of the guide cylinder 37 is set smaller than the inner diameter D2 of the cylinder hole 34 (D1 <D2), and the cylindrical piston guide 38 is basically the guide cylinder 37 and the booster cylinder 28.
Is slidably fitted to. The piston guide 38 has a land 39 slidably fitted in the guide cylinder 37 at the front end, and a land slidably fitted in the cylinder hole 34.
40 is provided at the rear end, and the guide cylinder 37 is provided on the land 39.
The cup seal 41, which is in sliding contact with the inner surface of the
A cup seal 42, which is in sliding contact with the inner surface of the cylinder hole 34, is fitted therein. As a result, an annular hydraulic chamber 43 is formed between the guide cylinder 37, the booster cylinder 28, and the piston guide 38. On the other hand, an annular oil chamber 44 is formed between the booster cylinder 28 and the guide cylinder 37, and this oil chamber 44 is
It communicates with the annular hydraulic chamber 43 via an oil passage 45 between a notch provided at the rear end of the guide cylinder 37 and the step portion 35. Further, the booster cylinder 28 is provided with an oil pressure source (not shown) in the oil chamber 44.
An inlet oil passage 46 that communicates with the
The hydraulic pressure from the hydraulic pressure supply source is constantly supplied to 43. Moreover, since D1 <D2 as described above, the piston guide 38 is pressed rearward by the hydraulic pressure of the annular hydraulic chamber 43, and unless there is a hydraulic pressure failure, the piston guide 38 is located behind the booster cylinder 28. Land on the control collar 47 provided at the end.
It is in the backward limit position where 40 abuts. Also piston guide 38
Between the front end and the holding member 27 that is pressed against the rear end of the cylinder body 2 in the master cylinder M, for pressing the piston guide 38 toward the retracted limit position when a hydraulic pressure failure occurs. The return spring 48 is contracted.

The piston guide 38 has a first cylinder hole 50 with an inner diameter D3.
And a second cylinder hole portion 51 coaxially connected to the rear end portion of the cylinder hole portion 50 and having an inner diameter D4 (D3> D4) smaller than the inner diameter D3. A booster piston 52 is slidably fitted in the first and second cylinder holes 50, 51. That is, the booster piston 52 is the first
A large-diameter portion 52a slidably fitted in the cylinder hole 50, and a small-diameter portion 52b connected to the rear end of the large-diameter portion 52a and slidably fitted in the second cylinder hole 51. And has a basically cylindrical shape. Further, an annular groove 53 is provided in the large diameter portion 52a of the booster piston 52, and both end edges of the annular groove 53 along the axial direction of the large diameter portion 52a are cups slidably contacting the inner surface of the first cylinder hole portion 50. Seals 54 and 55 are fitted, and a cup seal 56, which is in sliding contact with the small diameter portion 52b of the booster piston piston 52, is fitted in the second cylinder hole portion 51 of the piston guide 38.

An annular input hydraulic chamber 5 is formed between the piston guide 38 and the large diameter portion 52a of the booster piston 52 by an annular groove 53.
7 is defined, and an oil passage 58 for communicating the input hydraulic chamber 57 with the annular hydraulic chamber 43 is bored in the piston guide 38.
Further, between the piston guide 38 and the booster piston 52, an annular output hydraulic chamber 59 facing the rear surface of the large diameter portion 52a of the booster piston 52 is defined.

A cylindrical receiving member 60 is fitted on the rear end of the booster piston 52, and between the receiving member 60 and the rear end of the piston guide 38, a stroke adjustment for biasing the booster piston 52 rearward is performed. The spring 61 is retracted. Furthermore, the front of the booster piston 52 has a control collar that projects outward in the radial direction.
62 is integrally provided so as to be able to contact the front end of the piston guide 38, thereby defining the backward limit of the booster piston 52 with respect to the piston guide 38.

The booster piston 52 has a small diameter cylinder hole on the front side.
63 and a large-diameter cylinder hole portion 64 on the rear side are coaxially bored, and a valve piston 65 connected to the push rod 1 as an operating member slides on these cylinder hole portions 63, 64. It is possible to be fitted. That is, the valve piston 65 is a small diameter portion slidably fitted in the small diameter hole portion 63 via the seal member 66.
65a and a large diameter portion 65b slidably fitted in the large diameter hole portion 64 are coaxially connected, and the push rod 1 is coaxially connected to the rear end of the large diameter portion 65b. The tip of the small diameter portion 65a of the valve piston 65 slidably penetrates the guide member 21 and is projected into the boost chamber 24. Moreover, a seal member 67 that is in sliding contact with the outer surface of the small diameter portion 65a is fitted on the inner surface of the guide member 21.

An outlet chamber 68 is defined between the holding member 27 and the tubular body 8 of the master cylinder M and the front end of the booster piston 52 by defining the outer periphery of the guide tubular body 37. In addition, connecting tube parts 25, 29
And an annular oil passage 69 is defined between the guide cylinder 37,
The annular oil passage 69 communicates with the outlet chamber 68 via a communication hole 70 formed in the connecting tubular portion 25. Further, an outlet oil passage 71 communicating with the annular oil passage 69 is bored in the connecting tubular portion 29, and the outlet oil passage 71 is connected to an oil tank (not shown). Therefore, the outlet chamber 68 leads to the oil tank.

An inlet valve 72 for communicating and shutting off the input hydraulic chamber 57 and the output hydraulic chamber 59, and an outlet valve 73 for communicating and shutting off between the output hydraulic chamber 59 and the outlet chamber 68 include a booster piston 38.
And valve piston 65.

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 that is in communication with the input hydraulic chamber 57 and is formed in the booster piston 52. 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. Moreover, on the booster piston 52,
A communication hole 76 is formed for always communicating the annular recess 74 with the output hydraulic chamber 59 regardless of the relative movement of the valve piston 65 in the axial direction.

The inlet valve 72 is opened when the inlet valve hole 75 communicates with the annular recess 74, and when the valve piston 65 is in the retreat limit with respect to the booster piston 52, the inlet valve hole 75 is released from the annular recess 74. Also, the positions of the inlet valve hole 75 and the annular recess 74 are set so that the valve is closed at the front position.

Further, the valve piston 65 is provided with an oil supply passage 77 formed along the axial direction from the intermediate portion to the tip thereof, and the rear end of the oil supply passage 77 is always communicated with the annular recess 74. Therefore, when the inlet valve 72 is opened, the oil pressure is also supplied to the oil supply passage 77, and the front end of this oil supply passage 77 is at the boost chamber.
24 is connected to the boost chamber 24 when the inlet valve 72 is opened.
Also, the hydraulic pressure will be supplied.

The outlet valve 73 is connected to the piston guide 38 to communicate with the outlet chamber 68.
And a first outlet valve hole 79 communicating with the annular chamber 78 formed between the front ends of the booster pistons 52 and formed in the booster piston 52, and a valve piston 65 communicating with the oil supply passage 77. The second outlet valve hole 80 and the second outlet valve hole 80 are formed in the radial direction of the booster piston 52 and the valve piston 65 at positions corresponding to each other. In the outlet valve 73, when the valve piston 65 is in the backward limit with respect to the booster piston 52, the first and second
The outlet valve holes 79, 80 communicate with each other and are slightly opened, and when the forward movement of the valve piston 65 with respect to the booster piston 52 is started, the valve is closed before the inlet valve 72 is opened. To do. Moreover, when the outlet valve 73 is open, the oil supply passage 77 communicates with the outlet chamber 68, and the hydraulic pressures in the boost chamber 24 and the output hydraulic chamber 59 are released.

A circlip 81, which abuts on the rear end of the valve piston 65 and regulates the backward limit of the valve piston 65, is fitted on the receiving member 60 screwed on the rear end of the booster piston 52. A spring 82 is contracted between the receiving member 60 and the rear end of the valve piston 65, and the spring 82 urges the valve piston 65 toward the rear side.

Next, the operation of this embodiment will be described. When the brake pedal P is in the non-actuated state, the valve piston 65 is held at the retracted limit with respect to the booster piston 52 by the spring force of the spring 82, and the booster piston 52 adjusts the stroke. Spring 61
Therefore, the piston guide 38 is held in the retracted limit. Moreover, the piston guide 38 is at the retracted limit where the land 40 at the rear end abuts on the restricting flange portion 47 of the booster cylinder 28 by the hydraulic pressure supplied to the annular hydraulic chamber 43. In this state, the inlet valve 72 is closed and the outlet valve 73 is opened, so the output hydraulic chamber 59 and the boost chamber 24 are in the atmospheric pressure state.

When the brake pedal P is depressed to brake the vehicle in this state, the valve piston 65 is pushed forward from the brake pedal P via the push rod 1, the outlet valve 73 is closed first, and then the inlet valve 72 is closed. Open the valve. For this reason the boost chamber 24
Is introduced from the input oil pressure chamber 57 through the oil supply passage 77, and the working piston 4 receives the oil pressure on its rear surface and moves forward,
The boosting operation of the master cylinder M is started.

By the way, when the inlet valve 72 is opened, the hydraulic pressure is supplied to the boost chamber 24 as described above, the hydraulic pressure is also supplied to the output hydraulic chamber 59, and the booster piston 52 also receives the hydraulic pressure on its rear surface, so that the valve is Since it moves forward relative to the piston 65, the inlet valve 72 is closed and the outlet valve 73 is opened. Then, before the valve of the inlet valve 72 is closed and the valve of the outlet valve 73 is opened, the working piston 4 is moved forward by the hydraulic pressure acting on the boost chamber 24, and the characteristic line P ₀ -P ₁ shown by the solid line in FIG. Thus, the output hydraulic pressure of the master cylinder M rapidly increases. As a result, the play of each part up to the brake terminal is immediately removed.

After the output hydraulic pressure reaches P ₁ , the valve piston 65 moves forward in response to the depression of the brake pedal P, so that the valve piston 65 moves forward with respect to the booster piston 52 and the booster piston 52 moves forward with respect to the valve piston 65. Are alternately repeated, and the opening and closing of the inlet valve 72 and the outlet valve 73 are alternately repeated.
The hydraulic pressure, that is, the amount of forward movement of the working piston 4 also increases according to the amount of forward movement of the valve piston 65, and as shown by the characteristic line P ₁ -P ₂ , the output hydraulic 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, thereafter, only the valve piston 65 moves forward with the inlet valve 72 kept open by the depression force of the brake pedal P. However, when the hydraulic pressure in the boost chamber 24 becomes larger than the depression force of the brake pedal P, the valve piston 65 is pushed back and the inlet valve 72 is closed. When the brake pedal P is further depressed, the valve piston 65 moves forward again to open the inlet valve 72. By repeating such action hydraulic boost chamber 24 abruptly increases as shown by a characteristic line P ₂ -P ₃ of Figure 2. When the depression force of the brake pedal P becomes larger than the hydraulic pressure (hydraulic pressure) of the boost chamber 24,
The valve piston 65 advances at once, but the booster piston 52
Since the large-diameter portion 65b of the valve piston 65 to the rear end of the small diameter portion 52b abuts on the forward of the valve piston 65, as shown in the second diagram of characteristic lines P ₃ -P ₄ is stopped in little stroke operation stops To do. Moreover, the back-and-forth movement of the valve piston 65 is
Since the inlet valve 72 is a very minute movement that opens or closes, the operation feeling is not impaired.

When the brake pedal P is released to release the operation of the master cylinder M, the spring force of the spring 82 causes the valve piston 65 to first close the inlet valve 72 and then open the outlet valve 73. As a result, the hydraulic pressure in the boost chamber 24 is released, the working piston 4 is retracted to the backward limit, and the hydraulic pressure in the output hydraulic chamber 59 is released, so that the booster piston 52 has its regulating flange 62 due to the spring force of the stroke adjusting spring 61. Piston guide 38
Proceed backwards until it contacts the front end of the.

In such a hydraulic booster, the characteristic line P ₁ − in FIG.
P ₂ is the booster piston 52 by the oil pressure of the resulting and output hydraulic chamber 59 to the inner diameter D3 is larger (D3> D4) than the inner diameter D4
Is determined by the balance between the hydraulic pressure that presses the cylinder toward the front side and the spring force that biases the booster piston 52 toward the rear side by the stroke adjusting spring 61. The range in which the output hydraulic pressure of the master cylinder M corresponds to the stroke is Inside diameter D
It can be arbitrarily set by adjusting the loads of 3, D4 and the stroke adjusting spring 61. Therefore, as compared with the strokeless type shown by the chain line A in FIG. 2, it is possible to make the operation amount correspond to the operation amount in an arbitrary range to eliminate discomfort, and the stroke type shown by the chain line B in FIG. The stroke can be shortened compared to the one.

It is also assumed that a hydraulic pressure failure occurs in the hydraulic booster. In this case, since the oil pressure in the annular hydraulic chamber 43 decreases, the piston guide 38 is held in the retracted 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 the booster piston 52 and piston guide 38 move forward while contracting the stroke adjusting spring 61 and the return spring 48. When actuated, the valve piston 65 abuts on the rear end of the actuating piston 4 and pushes the actuating piston 4 forward. As a result, the 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 38 causes the tip of the booster piston 52 that abuts the guide member 21 to move the guide member 21 into the cylindrical body 8.
While pushing it in, it continues until it comes into contact with the rear end of the tubular body 8, whereby a sufficient output hydraulic pressure can be obtained from the master cylinder M, and a sufficient braking hydraulic pressure can be obtained even when the hydraulic pressure fails. Moreover, since the guide member 21 is slidable in the tubular body 8, the guide member 21 can be set relatively long while ensuring the stroke of the valve piston 65 in the event of hydraulic pressure failure. By making the length of 21 relatively long, it is possible to sufficiently guide the valve piston 65.

C. 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, slidably fitted to the piston guide provided on the booster cylinder, and the rear side. Between the output hydraulic chamber formed facing the back surface of the booster piston that is spring-biased and the input hydraulic chamber that communicates with the hydraulic supply source, is connected to the operating member and is slidably fitted to the booster piston. An inlet valve that opens according to the forward movement of the valve piston with respect to the booster piston is provided, and between the output hydraulic chamber and the outlet chamber that communicates with the oil tank, according to the forward movement of the valve piston with respect to the booster piston. An outlet valve for closing the valve is provided, and the working piston in the master cylinder is slidably fitted in a cylinder body fixed to the cylinder body. A boost chamber facing the back surface of the working piston is formed between the guide member fitted to the rear part of the cylindrical body so as to be able to contact the guide member, and the tip of the valve piston guides the guide member to the oil. Since it penetrates densely and movably into the boost chamber and penetrates into the boost chamber, and the valve piston is provided with an oil supply passage that communicates between the input hydraulic 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 to the rear side and the pressure receiving area of the booster piston that faces the output hydraulic chamber, it is possible to arbitrarily set the range in which the stroke of the operating member corresponds to the output hydraulic pressure. , The stroke of the operating member is set to the intermediate range of the conventional strokeless type and stroke type,
It is possible to eliminate discomfort.

Moreover, since the guide member is slidably fitted in the tubular body, the stroke of the operating member can be made relatively large by sliding the guide member according to the movement of the booster piston when the hydraulic pressure fails, so that the valve piston It is possible to make the length of the guide member relatively large in order to sufficiently guide the.

[Brief description of drawings]

The drawings show one embodiment of the present invention. FIG. 1 is a vertical side view and FIG. 2 is a characteristic diagram. 1 ... Push rod as operation member, 2 ... Cylinder body, 4 ... Working piston, 8 ... Cylindrical body, 21 ... 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 passage, M ... Master cylinder

Front page continuation (72) Inventor Yukitaka Miyagawa 1-4-1 Chuo, Wako-shi, Saitama, Ltd. Inside the Honda R & D Co., Ltd. (72) Inventor Kazuya Sakurai 1-1-4 Chuo, Wako-shi, Saitama Honda Corporation Inside the technical laboratory

Claims (1)

(57) [Claims] 1. A back surface of a booster piston, wherein a booster cylinder is connected to a rear end of a cylinder body of a master cylinder, slidably fitted to a piston guide provided on the booster cylinder, and biased backward by a spring. Between the output hydraulic chamber formed in front of the booster piston and the input hydraulic chamber that communicates with the hydraulic pressure source An inlet valve that opens in response to the valve is provided, and between the output hydraulic chamber and the outlet chamber that communicates with the oil tank, an outlet valve that closes in response to the forward movement of the valve piston with respect to the booster piston is provided. The working piston in the master cylinder is slidably fitted to a cylinder body fixed to the cylinder body, and can be brought into contact with the tip of the booster piston so that the rear portion of the cylinder body can be contacted. A boost chamber facing the back of the working piston is formed between the slidably fitted guide member and the working piston, and the tip of the valve piston allows the guide member to move oil-tightly and freely. A hydraulic booster, which penetrates into the boost chamber, and is provided with an oil supply passage for communicating between the input hydraulic chamber and the boost chamber according to opening of the inlet valve in the valve piston. apparatus.