JPH01141157A - Hydraulic booster - Google Patents

Abstract

PURPOSE:To aim at the miniaturization of a return spring by opening an inlet valve at the initial stage of braking operation, feeding a boost chamber with hydraulic pressure, and when an actuating piston of a master cylinder is advanced and operated, making reaction force given to a booster piston bearable with an accumulator. CONSTITUTION:A booster piston 43 being energized in the rear by a return spring 46 is fitted in a piston guide 30 installed in a booster cylinder 24 ranging to the rear end of a master cylinder M. An inlet valve 76, which is opened according to movement of a valve piston 66 being operated by an operating member 1, is installed interpositingly between an output hydraulic chamber 47 and an input hydraulic chamber 60 partitioned off by this booster piston. Likewise, an output valve 77, which is closed according to movement of the valve piston 66, is installed interposingly between the output hydraulic chamber 47 and an outlet chamber 62. In the valve piston 66, there is provided with an oil feed passage 73 which interconnects an interval between the input hydraulic chamber 60 and a booster chamber 67 according to opening of the inlet valve 76. In addition, a reaction chamber 48 is formed as adjoined in front of the booster piston 43, and an accumulator 49 is connected to this reaction chamber 49.

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) Prior Art Conventionally, such a hydraulic booster is known, for example, as disclosed in Japanese Patent Application Laid-Open No. 113549/1983.

(3) Problems to be Solved by the Invention By the way, the above-mentioned conventional system has an operating member in a booster piston that can slide in the booster cylinder of the hydraulic booster and can come into contact with the operating piston of the master cylinder. The continuous valve pistons are slidably fitted, and the supply of hydraulic pressure to the output hydraulic chamber facing the rear side of the booster piston and the release of hydraulic pressure from the output hydraulic chamber are switched in accordance with the relative operation of the booster piston and the valve piston. I have to. Therefore, in the initial stage of operation by the operating member, the start of operation of the booster piston tends to be delayed due to friction between the seal portion between the booster piston and the booster cylinder, and therefore, the initial operation of the operating piston in the master cylinder cannot be said to be smooth.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a hydraulic booster that smoothes the initial operation of an operating piston in a master cylinder and that can be downsized.

B0 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 chamber, which is formed facing the front of the booster piston that is fitted together and is biased rearward by a spring, and the input hydraulic chamber that 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 that closes in response to the forward movement of the inlet valve is provided, and a boost chamber is formed facing the rear end of the working piston in the master cylinder, and an input hydraulic chamber is provided in the valve piston in response to the opening of the inlet valve. and an oil supply passage that communicates between the boost chamber and the outlet chamber in response to the opening of the outlet valve, and a reaction force chamber whose volume is reduced in accordance with the forward movement of the booster piston. An accumulator is connected to the reaction force chamber.

(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, so that the booster Regardless of the operation of the piston, hydraulic pressure acts on the rear end of the working piston to push the working piston forward. Therefore, the initial operation of the operating piston in the master cylinder can be smoothed. Moreover, the reaction force determined by the accumulator acts from the front on the booster piston, which is pushed forward by the hydraulic pressure in the output hydraulic chamber, making it possible to reduce the spring force that urges the booster piston rearward. This makes it possible to contribute to miniaturization.

(3) Examples Examples of the present invention will be explained below with reference to the drawings.
First, in FIG. 1 showing an embodiment of the present invention, this hydraulic booster is for a brake device mounted on an automobile, and consists of a hydraulic booster B connected to the rear of a master cylinder M. A bushing rod 1 as an operating member interlocked and connected to the brake pedal P is connected to the brake pedal P.
By operating forward in response to the depressing operation, the hydraulic booster B performs a boosting operation, and braking hydraulic pressure is generated in the master cylinder M accordingly.

The master cylinder M is a tandem type master cylinder, and the cylinder body 2 is provided with a cylinder hole 3 whose front end is closed, and one hydraulic chamber is formed between the cylinder hole 3 and the front end wall. The working piston 4 on the front side and the working piston 6 on the rear side forming the other hydraulic chamber 5 between the working piston 4 and the working piston 6 on the rear side are slidably fitted, and the working piston 4 on the front side A spring (not shown) is interposed between the working piston 4 on the front side and the working piston 6 on the rear side. A spring 7 is interposed to urge the piston 6 rearward. Therefore, by pressing the rear working piston 6 forward, the volumes of the front hydraulic chamber and the rear hydraulic chamber 5 are contracted, and braking oil pressure is output from these hydraulic chambers 5.

At the rear of the cylinder body 2, a connecting cylinder part 9 which forms a stepped part 8 between the cylinder hole 3 and the cylinder hole 3 is provided to protrude coaxially with the cylinder hole 3. On the other hand, a front end portion of a piston rod 10 extending rearward is fixed to the operating piston 6, and a guide member 11 is fixed to the rear portion of the cylinder body 2 to guide the movement of the piston rod 10. This guide member 11 is
A fitting cylinder part 11a that fits into the rear end of the cylinder hole 3, and a flange-shaped contact light part 11b that extends radially outward from the rear end of the fitting cylinder part ILa, and the contact light The portion 11b is fitted into the connecting cylinder portion 9 in an oil-tight manner and is brought into contact with the stepped portion 8. In addition, the contact light is transmitted when the portion 11b is in contact with the stepped portion 8, and the retaining ring 22 that engages with the outer peripheral edge of the portion 11b is fitted onto the inner surface of the connecting cylinder portion 9, so that the guide member 11 is fixed to the cylinder body 2. Also, the piston rod lO
penetrates the guide member 11 in an oil-tight and movable manner and extends toward the hydraulic booster B side.

A replenishment oil chamber 12 is provided between the guide member 11 and the operating piston 6.
The cylinder body 2 is provided with an oil passage 15 that communicates an oil reservoir 14 in an oil tank 13 formed in the upper part of the cylinder body 2 with the supply oil chamber 12. Further, a cup seal 16 that slides into contact with the inner surface of the cylinder hole 3 is fitted to the operating piston 6, and the cup seal 16 and the operating piston 6 are used to supply oil when the pressure in the hydraulic chamber 5 is lower than that in the supply oil chamber 12. It is configured to allow flow of hydraulic oil from the oil chamber 12 to the hydraulic chamber 5.

A valve mechanism 18, which is driven to open and close by a stopper pin 17, is provided at the front of the operating piston 6 to open and close the hydraulic chamber 5 and the supply oil chamber 1.
The valve mechanism 1 is arranged to communicate and cut off the
8 is pressed by a stopper pin 17 to open the valve when the actuating piston 6 returns to the retraction limit. The stopper pin 17 is elongated in the axial direction (and has a long hole 1 bored in the piston rod 10).
The stopper pin 17 is inserted into the piston rod 10 so as to be perpendicular to the axis of the piston rod 10, and both ends of the stopper pin 17 protrude from the outer surface of the piston rod 10. It is fixed to a shaped holder 20. Furthermore, the holder 20 is biased in the direction of contacting the guide member 11 by a spring 21 interposed between the holder 20 and the actuating piston 6, so that the stopper pin 17 is substantially fixed to the cylinder body 2. Become.

A booster cylinder 24 of a hydraulic booster B is coaxially joined to the rear end of the cylinder body 2, and the cylinder body 2 and the booster cylinder 24 are connected by bolts 25.

That is, a flange 26 provided at the front end of the booster cylinder 24 and a flange 27 provided at the rear end of the cylinder body 2 are coupled by bolts 25.

A cylinder hole 28 is bored in the booster cylinder 24 coaxially with the cylinder hole 3 of the master cylinder M, and a guide cylinder 29 is slidably fitted into the cylinder hole 28. The front part of the guide cylinder 29 has a stepped part 29a that comes into contact with the rear end of the connecting cylinder part 9 in the cylinder body 2.
A small-diameter cylindrical portion 29b coaxially protrudes through the connecting cylindrical portion 9, and is fitted into the connecting cylindrical portion 9 in an oil-tight manner. Further, a cylindrical piston guide 30 is slidably fitted into the cylinder hole 28, and a small diameter cylindrical part 30a which is slidably fitted into the guide cylinder 29 is stepped at the front part of the piston guide 30. They are coaxially connected via the portion 30b. Furthermore, a spring 31 is provided between the guide cylinder 29 and the piston guide 30, which exerts a spring force in a direction to separate them from each other. Further, a cylinder 32 is oil-tightly fitted into the rear end of the piston guide 30, and the cylinder 32 is fitted in a radial direction at the rear end of the booster cylinder 24. It is engaged with the regulating flange 33 that protrudes toward the side.

An annular hydraulic chamber 34 is formed between the booster cylinder 24, the guide cylinder 29, and the piston guide 30.
An inlet oil passage 35 communicating with 4 is bored. Moreover, the spring 31 is housed in the annular hydraulic chamber 34, and the piston guide 30 is biased toward the rear side by the hydraulic pressure introduced into the annular hydraulic chamber 34 and the spring 31, and the guide cylinder 29 is urged toward the front side. is energized by Further, an annular oil chamber 36 is formed between the guide cylinder 29 and the booster cylinder 24, and an outlet oil passage 37 that communicates the oil chamber 36 with an oil tank (not shown) is bored in the booster cylinder 24. Further, an annular oil passage 38 is formed between the small diameter cylindrical portion 30a of the piston guide 30 and the guide cylinder 29, and an oil passage 39 that communicates the annular oil passage 38 with the oil chamber 36 is bored through the guide cylinder 29. will be established.

The piston guide 30 has a first cylinder hole 41 on the front end side and a first cylinder hole 41 with a diameter larger than the first cylinder hole 41.
A second cylinder hole 42 coaxially connected to the cylinder hole 41
are bored, and the first and second cylinder holes 41
, 42, a booster piston 43 is slidably fitted therein. That is, the booster piston 43 has a small diameter portion 43a that is slidably fitted into the first cylinder hole 41, and a large diameter portion that extends radially outward at the rear end of the small diameter portion 43a and slides into the second cylinder hole 43. It has a diameter portion 43b and is basically formed in a cylindrical shape. The rear end portion of the booster piston 43 extends rearwardly through the receiver tube 32 in an oil-tight and movable manner. A retaining ring 44 is fitted to the outer surface of the rear end of the booster piston 43, and a return spring 46 is compressed between a member 45 of the retaining ring 44 and the retaining tube 32. be done. Therefore, the booster piston 43 is urged rearward.

An annular output hydraulic pressure chamber 47 is defined between the large diameter portion 43b of the booster piston 43 and the receiver tube 32, and therefore the output hydraulic pressure chamber 47 is formed facing the back surface of the booster piston 43. become. Further, an annular reaction force chamber 48 is defined between the large diameter portion 43b of the booster piston 43 and the stepped portion 30b of the piston guide 30, and the reaction force chamber 48 faces the front surface of the booster piston 43. Become.

An accumulator 49 is connected to the reaction force chamber 48 , and the accumulator 49 is attached to the booster cylinder 24 . This accumulator 49 includes a bottomed cylindrical mounting body 50 that is hinged to the booster cylinder 24, a bottomed cylindrical cylinder body 51 that is screwed into the mounting body 50 in an oil-tight manner, and A piston that forms an oil chamber 52 between the closed end of the body 50 and a spring chamber 53 between the closed end of the cylinder body 51 and is fitted oil-tightly and slidably into the cylinder body 51. 54, and a spring 55 housed in the spring chamber 53 to bias the piston 54 in the direction of contracting the oil chamber 52. Moreover, the pressure receiving area of the piston 54 facing the oil chamber 52 is set smaller than the pressure receiving area of the booster piston 43 facing the reaction force chamber 48. This accumulator 49 is attached to the booster cylinder 24 so that its oil chamber 52 is located below the oil sump 14 of the oil tank 13.

The mounting body 50 is screwed onto the booster cylinder 24 with a seal member 56 interposed between it and the outer surface of the booster cylinder 24, and an oil chamber 5 is provided at the closed end of the mounting body 50.
An oil passage 57 leading to the booster cylinder 24 is bored.
an oil passage 58 that communicates the oil passage 57 with the reaction force chamber 48;
is drilled.

An annular input hydraulic chamber 60 whose axial ends are oil-tightly sealed is formed between the intermediate portion of the small diameter portion 43a of the booster piston 43 and the inner surface of the first cylinder hole portion 41 of the piston guide 30. A communication hole 61 is bored in the small diameter cylindrical portion 30a of the guide 30 to allow the input hydraulic pressure chamber 60 to communicate with the annular hydraulic chamber 34 regardless of the forward movement of the booster piston 43. Further, on the outer surface of the small diameter portion 43a of the booster piston 43 on the front side of the input hydraulic pressure chamber 60, an annular recess is provided to form an annular outlet chamber 62 whose axial ends are sealed.
Regardless of the operation of the booster piston 43, the annular oil passage 3
The communication hole 63 that is always in communication with the piston guide 30
The small diameter cylindrical portion 30a is bored. Therefore, the exit chamber 62
will be constantly communicated with the oil tank.

The booster piston 43 has a small-diameter cylinder hole 64 on the front side and a large-diameter cylinder hole 65 on the rear side coaxially bored, and the small-diameter cylinder hole 64 has a valve piston connected to the bushing rod 1. 66 is slidably fitted. On the other hand, the rear end of the piston guide 10 coaxially connected to the actuating piston 6 in the master cylinder M is inserted into the front end of the piston guide 30 facing the front end of the booster piston 43. The boost chamber 67 facing the rear end is connected to the connecting cylinder part 9 and the guide member 11.
, the guide cylinder 29, the piston guide 30, the booster piston 43, and the valve piston 66. When hydraulic pressure is introduced into the boost chamber 67, the operating piston 6 moves forward.

A connecting rod 68 is slidably fitted in a large diameter cylinder hole 65 of the booster piston 43 in an oil-tight manner, and the front end of the connecting rod 8 is connected to the rear end of the valve piston 66. Further, the front end of the bushing rod 1 is connected to the rear end of the connecting rod 68. Moreover, booster piston 4
A retaining ring 69 is fitted onto the inner surface of the rear end portion of the valve 3 to abut against the rear end of the connecting rod 68 to restrict the backward limit of the connecting rod 68, that is, the valve piston 66. Furthermore, booster piston 4
A spring 71 that urges the valve piston 66 rearward is compressed between a retaining ring 70 fitted on the inner surface of the front end of the valve 3 and the front end of the valve piston 66.

The valve piston 66 has a boost chamber 6 open at its front end.
An oil supply passage 73 is coaxially bored and communicates with the booster piston 43 , the valve piston 66 , and the connecting rod 68 . Further, the booster piston 43 has the annular chamber 7.
An oil passage 75 is bored through which the output oil pressure chamber 4 communicates with the output oil pressure chamber 47. Therefore, the boost chamber 67 and the output hydraulic pressure chamber 47 are always in communication via the oil supply passage 73.

Between the valve piston 66 and the booster piston 43, there is an inlet valve 76 that communicates and blocks communication between the human hydraulic pressure chamber 60 and the oil supply passage 73, and an inlet valve 76 that communicates between the outlet chamber 62 and the oil supply passage 73.
Outlet valve 77 that performs shutoff, reaction force chamber 48 and oil supply path 7
An on-off valve 78 is provided for communicating and blocking communication between the three.

The inlet valve 76 includes an annular recess 79 that communicates with the oil supply path 73 and is provided on the outer surface of the intermediate portion of the valve piston 66, and an input hydraulic chamber 6.
The annular recess 79 is relatively long (provided) in the axial direction of the valve piston 66, and the inlet valve hole 80 is connected to the booster piston 43. It is bored along the radial direction of the piston 43.

The inlet valve 76 opens when the inlet valve hole 80 communicates with the annular recess 79 , and when the valve piston 66 is at its retracting limit with respect to the booster piston 43 , the inlet valve hole 80 opens from the annular recess 79 . The positions of the annular recess 79 and the inlet valve hole 80 are set such that the valve piston 66 is in the forward position and the valve is in the closed state, and the valve piston 66 is in the forward position and the valve is in the closed state.
The valve opens when the valve moves forward.

The outlet valve 7-7 communicates with the oil supply passage 73 and is connected to the valve piston 66.
A first Yamaguchi valve hole 81 is bored in the booster piston 43, and a second outlet valve hole 82 is in communication with the outlet chamber 62 and is bored in the booster piston 43.
and both outlet valve holes 81 and 82.
are bored along the radial direction of the valve piston 66 and the booster piston 43 at mutually corresponding positions. In such a valve 77, the valve piston 66 is connected to the booster piston 4.
3, the first and second outlet valve holes 81 and 82 communicate with each other and are slightly open, and the valve piston 66 starts to move forward relative to the booster piston 43. When this happens, the inlet valve 76 is closed before it opens.

The on-off valve 78 includes the annular recess 79 and a valve hole 83 that communicates with the reaction force chamber 48 and is bored in the booster piston 43. In this opening/closing valve 78, when the valve piston 66 is at the retraction limit with respect to the booster piston 43, the valve hole 83 communicates with the annular recess 79 and is slightly opened. When forward movement is started, the outlet valve 77 closes before it closes.

Next, the operation of this embodiment will be explained. When the brake pedal P is not actuated, the valve piston 66 is held at the backward limit with respect to the booster piston 43 by the spring force of the spring 71; The piston guide 30 is held at the backward limit by the piston guide 30.

In this state, the inlet valve 76 is closed and the outlet valve 7 is closed.
7 and the on-off valve 78 are open, so the boost chamber 67, the output hydraulic pressure chamber 47, and the reaction force chamber 48 are at atmospheric pressure. Therefore, the actuating piston 6 of the master cylinder M is retracted by the spring 7 to the retracting limit.

When the brake pedal P is depressed to brake the automobile in this state, the valve piston 66 is pushed forward by the brake pedal P via the bushing rod 1 and the connecting rod 68. In response to the forward motion of the valve piston 66 relative to the booster piston 43, the outlet valve 77 first closes, the on-off valve 78 closes, and then the inlet valve 76 opens. For this reason, the input hydraulic chamber 60 and the boost chamber 67 communicate with each other,
By introducing the working hydraulic pressure into the boost chamber 67, the working piston 6 receives the hydraulic pressure on its back and moves forward, and the master cylinder M
boost operation is started.

At the beginning of such boosting operation, the valve piston 6
6 moves forward until the inlet valve 76 is opened, hydraulic pressure is supplied to the boost chamber 67 and the working piston 6 is moved forward. Compared to the conventional case, the operating piston 6 can be quickly pressed and operated regardless of the friction of the seal between the booster piston 43 and the piston guide 30, and the initial operation of the operating piston 6 can be made smooth.

By the way, when the inlet valve 76 opens, as described above, hydraulic pressure is supplied to the boost chamber 67 and also to the output hydraulic chamber 47, and the booster piston 43 also receives hydraulic pressure on its front surface, so that the valve piston 66 Since it moves forward relative to the inlet valve 76, the inlet valve 76 is closed and the outlet valve 77 is opened. Therefore, the inlet valve 7
The working piston 6 moves forward due to the hydraulic pressure acting on the boost chamber 67 before the valve 6 closes and the outlet valve 77 opens, and the output hydraulic pressure of the master cylinder M becomes as shown by the characteristic lines P and -P shown in FIG. Increase rapidly. As a result, play in various parts up to the brake terminal is immediately eliminated.

After the output oil pressure reaches PI, the valve piston 66 moves forward in response to the depression of the brake pedal P, so that the valve piston 66 moves forward relative to the booster piston 43, and the booster piston 43 moves forward relative to the valve piston 66. The opening and closing of the inlet valve 76 and the outlet valve 77 are alternately repeated. Therefore, the oil pressure in the boost chamber 67 and the amount of forward movement of the operating piston 6 also increase in accordance with the amount of forward movement of the valve piston 66.
As shown by the characteristic line P+'Pz, the output oil pressure of the master cylinder M increases according to the stroke.

By the way, when the valve piston 66 moves forward, the booster piston 4 moves forward by the hydraulic pressure in the output hydraulic chamber 47.
3 is a reaction force chamber 4 in front of the return spring 46 while contracting it.
The booster piston 43 moves forward while contracting its volume, and when the booster piston 43 moves forward, the on-off valve 78 is closed and the reaction chamber 48 is in a sealed state. For this reason, reaction force chamber 4
8 presses the piston 54 while contracting the spring 55 in the accumulator 49. Therefore, the booster piston 43 moves forward while receiving a reaction force from the spring 55 and a reaction force from the spring 46 on its front side.

When the stepped portion 43b of the booster piston 43 comes into contact with the stepped portion 30b of the piston guide 30 as the booster piston 43 moves forward,
The forward movement of the booster piston 43 is prevented. Therefore, from then on, the valve piston 66 is replaced by the booster piston 4.
3, the inlet valve 76 is opened and the outlet valve 77 and the on-off valve 78 are closed. .

Brake pedal P to release the operation of master cylinder M
When opening, the spring 71 causes the valve piston 66 to first close the inlet valve 76 and then open the outlet valve 77. As a result, the hydraulic pressure in the boost chamber 67 is released and the actuating piston 6 retreats to the retraction limit, and the hydraulic pressure in the output hydraulic pressure chamber 47 and the reaction force chamber 48 is released, so that the booster piston 43 has its rear end supported by the return spring 46. quickly retreats to the retraction limit where it abuts the cylinder 32.

In such a hydraulic booster, the characteristic line P+ in FIG.
Pg is determined by the balance between the hydraulic pressure that presses the booster piston 43 forward by the hydraulic pressure of the output hydraulic chamber 47, the spring force that urges the booster piston 43 backward by the return spring 46, and the reaction force by the reaction force chamber 48. The range in which the output oil pressure of the master cylinder M corresponds to the stroke can be arbitrarily set by adjusting the loads of the return spring 46 and the spring 55. Moreover, in order to accommodate the stroke until the output oil pressure of the master cylinder M increases, it is necessary to increase the loads on the return spring 46 and the spring 55. However, by bearing most of the load on the accumulator 49, the return spring The load on the return spring 46 can be made relatively small, and therefore the return spring 46 can be made relatively small and its installation space can be reduced, contributing to miniaturization of the hydraulic booster B. Moreover, even if the load on the accumulator 49 is increased, the booster piston 43 facing the reaction force chamber 48
Since the pressure receiving area of the piston 54 facing the oil chamber 52 is smaller than that of the piston 54, the load on the spring 55 can be relatively small, and therefore the accumulator 49 can also be relatively small.

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 34 decreases, the piston guide 30 is held at the retracting limit by the spring 31. Therefore, when the brake pedal P is depressed to perform a braking operation, the valve piston 66 moves forward while contracting the spring 71, and the connecting rod 68 moves forward to the booster piston 43.
After coming into contact with , the booster piston 43 moves forward while contracting the spring 31 , and the front end of the booster piston 43 comes into contact with the rear end of the piston rod lO connected to the working piston 6 , moving the working piston 6 forward. Activate the pressure,
Output hydraulic pressure is generated in the master cylinder M. Furthermore, after the booster piston 43 comes into contact with the piston guide 30, the piston guide 30 also moves forward, and the piston guide 3
The forward movement of the valve piston 66 and the booster piston 43 continues until the cylinder 0 comes into contact with the guide cylinder 29, and as a result, sufficient output oil pressure can be obtained from the master cylinder M, and even in the event of oil pressure failure, sufficient braking oil pressure can be maintained. Obtainable.

FIG. 3 shows another embodiment of the present invention, in which the accumulator 49 of the previous embodiment is replaced with
An accumulator 49' is connected to the reaction chamber 48. This accumulator 49' consists of a Prada 87 sandwiched between a pair of hemispheres 85 and 86 that are connected to each other, and one hemisphere 85 has a connecting cylinder part 88 that is screwed onto the booster cylinder 24 integrally. provided. Moreover, an oil chamber 89 is defined between the bladder 87 and one hemisphere 85 , a gas chamber 90 is defined between the bladder 87 and the other hemisphere 86 , and the connecting cylinder 88 is provided with the booster cylinder 24 . An oil passage 91 is provided that communicates between the oil passage 58 and the oil chamber 89.

According to this embodiment, when the booster piston 43 moves forward, the hydraulic oil in the reaction chamber 48 enters the oil chamber 89 while deflecting the prada 87 toward the gas chamber 90, and the gas pressure due to the volume reduction of the gas chamber 90 is reversed. It acts on the booster piston 43 via the force chamber 48 . Therefore, similarly to the previous embodiment, the load on the return spring 46 can be reduced.

By the way, when such a hydraulic booster and an anti-lock brake device are installed in a vehicle, the kick-pack phenomenon of the anti-lock brake device can be alleviated. That is, an increase in the oil pressure in the boost chamber 67 due to kickback causes an increase in the oil pressure in the output oil pressure chamber 47, causing the booster piston 43 to move forward and the outlet valve 77 to open.

C9 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, is slidably fitted into the piston guide provided on the booster cylinder, and is slidably fitted to the rear end of the cylinder body of the master cylinder. An output hydraulic chamber formed facing the back of the spring-loaded booster piston and an input hydraulic chamber communicating with the 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 outlet valve is provided to form a boost chamber facing the rear end of the working piston in the master cylinder, and the valve piston is provided with an outlet valve for communicating between the input hydraulic chamber and the boost chamber in response to opening of the inlet valve. At the same time, an oil supply passage communicating between the boost chamber and the outlet chamber is drilled in response to the opening of the exit valve, and a reaction force chamber whose volume is reduced in accordance with the forward movement of the booster piston is formed facing in front of the booster piston. Since an accumulator is connected to the reaction force chamber, at the initial stage of operation by the operating member, the inlet valve is opened to supply hydraulic pressure to the boost chamber, the operating piston is moved forward, and the output hydraulic pressure is generated by the master cylinder. can be obtained. Therefore, compared to the conventional system in which the booster piston pushes the operating piston,
The operating piston can be quickly operated regardless of friction at the seal portion of the booster piston, and smooth initial operation can be achieved.

Moreover, since the accumulator bears the reaction force exerted on the booster piston, the spring that biases the booster piston rearward can be made smaller, thereby reducing the space for the spring and making it more compact. .

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional side view of one embodiment of the invention, FIG. 2 is an output characteristic diagram of the apparatus of the invention, and FIG. 3 is a longitudinal sectional side view of another embodiment of the invention. DESCRIPTION OF SYMBOLS 1... Bush rod as an operating member, 2... Cylinder body, 6... Operating piston, 24... Booster cylinder, 30... Piston guide, 43... Booster piston, 47... Output Hydraulic chamber, 48...Reaction force chamber, 49.49'...Accumulator, 60...
- Input hydraulic chamber, 66... Valve piston, 67... Boost chamber, 73... Oil supply path, 76... Inlet valve, 77...
...Outlet valve, M...Master cylinder

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. A boost chamber is formed facing the rear end, and the valve piston has communication between the input hydraulic chamber and the boost chamber in response to the opening of the inlet valve, and communication between the boost chamber and the outlet in response to the opening of the outlet valve. An oil supply passage communicating between the chambers is drilled, a reaction force chamber whose volume is reduced as the booster piston moves forward is formed facing the front of the booster piston, and an accumulator is connected to the reaction force chamber. Features a hydraulic booster.