JP2001163215A - Hydraulic booster - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic booster capable of improving durability while surely accumulating prescribed fluid pressure in an emergency accumulator. SOLUTION: When accumulating pressure of an emergency accumulator 9 is not more than preset pressure, a first ball valve 111 separates from a first seat part 108, a second ball valve 112 sits on a second seat part 109, and the accumulating pressure of the emergency accumulator 9 is introduced to a chamber 101 to act on a stepped piston 7. Thus, since a flow restriction valve 68 restricts a flow of a hydraulic fluid from a pump 6, fluid pressure is generated, and the generated fluid pressure is accumulated in the emergency accumulator 9. At this time, since a pressing surface 115a of a second pressing member 115 for pressing the second ball valve 112 is formed as a flat surface, the second pressing member 115 presses the second ball valve 112 only in the shaft direction. Thus, the second ball valve 112 closely and surely sits on the second seat part 109 without partial loading by eccentricity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic booster such as an open center type brake booster for increasing the braking force by boosting the depressing force of a brake pedal by the hydraulic pressure of hydraulic fluid in an automobile. The invention belongs to the technical field of a hydraulic booster provided with an emergency accumulator for storing an emergency hydraulic pressure for operating the hydraulic booster in the event of a hydraulic fluid pressure failure. .

[0002]

2. Description of the Related Art Some vehicles, such as automobiles, use a hydraulic boosting system that boosts the operating force of an operating member by the hydraulic pressure of hydraulic fluid and outputs the boosted power. As this hydraulic booster system, for example, a hydraulic brake booster that operates by the hydraulic pressure of the hydraulic fluid to obtain a large braking force that cannot be obtained only by the pedaling force of the brake pedal or to reduce the pedaling force There is a hydraulic brake system that operates the master cylinder by boosting the pedal depressing force by using the brake pedal. As such a hydraulic brake system,
Conventionally, there is a hydraulic brake system as shown in FIG. In the figure, 1 is a hydraulic brake system, 2 is a brake pedal,
Reference numeral 3 denotes an open center type hydraulic brake booster (hereinafter also referred to as a brake booster or simply a booster) which is operated by the brake pedal 2 and boosts the pedal depressing force, and 4 is operated by the output of the booster 3 and brake fluid. A tandem-type master cylinder that generates pressure, 5 is a brake cylinder that operates by the brake fluid pressure from the master cylinder 4 to generate a braking force on each wheel, and 6 is driven by an engine 7 to send hydraulic fluid to the booster 3 A pump for supplying, a reservoir for storing hydraulic fluid, and an emergency for storing an emergency hydraulic pressure for operating the booster when the pump does not supply hydraulic fluid due to a failure of the pump or the like. It is an accumulator.

In the open center type booster 3, the gap between the control valves is maximized when the brake is not operated, and the hydraulic fluid flows freely, and the flow of the hydraulic fluid is restricted by narrowing the gap between the control valves during the operation. A hydraulic pressure is generated and output by the hydraulic pressure, and various structures are conventionally known. An example of the booster 3 is shown in FIG. Since the booster 3 is conventionally known, and will be described in detail in a booster of the present invention described later, a portion related to a problem to be solved by the present invention will be briefly described here.

In the brake non-operation state shown in FIG. 4, the gap between the first annular groove 10 and the second annular groove 11 is maximized, and the second annular groove 11 and the third annular groove 12
And the third annular groove 12 and the fourth annular groove 13 communicate with each other. Therefore, the pump 6
The hydraulic fluid discharged from the inlet port 14 of the open center type booster 3, the second annular groove 11, the gap between the first annular groove 10 and the second annular groove 11, the first annular groove 10, and the circulation It circulates again to the reservoir 8 through the passage 15. In this case, since the gap between the first annular groove 10 and the second annular groove 11 is maximized, almost no hydraulic pressure is generated in the circulating hydraulic fluid.

In this state, when the input shaft 16 moves forward by depressing the brake pedal 2, a pair of levers 17 and 18 (the pair of levers overlap in a direction perpendicular to the drawing in FIG. 4) rotate to rotate the valve. The spool 19 moves forward. Then, the gap between the first annular groove 10 and the second annular groove 11 is narrowed, the second annular groove 11 communicates with the third annular groove 12, and the third annular groove 12 and the fourth annular groove 11 13 is cut off. When the gap between the first and second annular grooves 10 and 11 is reduced (the gap may eventually become zero), a hydraulic pressure is generated in the second annular groove 11. This hydraulic pressure passes through the gap between the second annular groove 11 and the third annular groove 12, the first radial hole 20, the axial hole 21, and the third check valve and the second radial hole 22. It is introduced into the power chamber 23 and acts on the power piston 24. As a result, the power piston 24 generates a bouquet operation force that is a boost of the pedal depression force, and this brake operation force is output from the output shaft 25 to operate the master cylinder 4 and operate the brake.

The hydraulic pressure generated in the second annular groove 11 is
The valve body 29 of the charging valve 28, which is a check valve of the accumulator valve 27, is moved rightward in FIG. 4 to separate the valve body 29 from the rubber sheet 30 and open the charging valve 28. As a result, this hydraulic pressure is applied to the gap between the valve body 29 and the rubber sheet 30, the valve body 2
The emergency accumulator 9 is introduced into the emergency accumulator 9 through the outer periphery of the accumulator 9 and the accumulator passage 31 and stored in the emergency accumulator 9.

When the brake pedal 2 is released, the input shaft 1
6 and the valve spool 19 are retracted to the inoperative position shown in FIG. 4, the third annular groove 12 and the fourth annular groove 13 communicate with each other, and the second annular groove 11 and the third annular groove 12 are shut off. ,
Further, the gap between the first annular groove 10 and the second annular groove 11 is maximized. For this reason, the hydraulic fluid in the power chamber 23 is
21, 20, the third annular groove 12, the gap between the third annular groove 12 and the fourth annular groove 13, the fourth annular groove 13, and the discharge passage 32 are discharged to the reservoir 8. As a result, the power piston 24 retreats to the non-operation position, the brake operation force disappears, the master cylinder 4 returns to the non-operation state, and the brake operation is released. When the gap between the first and second annular grooves 10 and 11 is maximized, the hydraulic pressure generated in the second annular groove 11 disappears.

When the pump 6 is out of order and no hydraulic pressure is generated even if the gap between the first annular groove 10 and the second annular groove 11 is reduced, the brake pedal 2 is further depressed. Accordingly, the valve spool 19 moves forward by the maximum stroke. When the brake pedal 2 is further depressed and the input shaft 16 is further advanced after the valve spool 19 stops moving forward, the levers 17 and 18 further rotate, and the slide valve 33 moves relative to the valve spool 19. Move forward. Then, the second radial hole 22 is closed, and the power chamber 23 is shut off from the pump 6. When the slide valve 33 further moves forward, the retainer 34 also moves forward.
7, the valve element 35 of the dump valve 36, which is a check valve, is advanced, the dump valve 36 is opened, and the hydraulic pressure stored in the emergency accumulator 9 is introduced into the power chamber 23, and the emergency accumulator 9 The power piston 24 is actuated by the hydraulic pressure. This allows
Even if the pump 6 fails, while the emergency accumulator 9 stores the predetermined hydraulic pressure, the emergency accumulator 9
By this hydraulic pressure, the pedal depression force is boosted and the brake can be operated.

However, in the hydraulic brake system 1, the pressure accumulation in the emergency accumulator 9 is performed by introducing the hydraulic pressure generated at the time of the brake operation, that is, the pump discharge pressure, into the emergency accumulator 9. For this reason, if the brake operation force is small, the pressure may not be sufficiently accumulated in the emergency accumulator 9, and the number of times the emergency accumulator 9 can be boosted by the hydraulic pressure when the pump 6 fails may decrease.

In view of the above, a hydraulic booster is provided in which the predetermined hydraulic pressure is reliably and sufficiently accumulated in the accumulator by the charging valve device so that the number of times that the emergency accumulator 9 can be boosted by the hydraulic pressure is increased when the pump 6 fails. The device is disclosed in
It has been proposed by Japanese Patent Publication No. 1-78856. In the hydraulic booster disclosed in this publication, when the accumulated pressure of the emergency accumulator is equal to or less than the set pressure, the pressure control valve that controls the charging operation of the charging valve device on / off controls the emergency accumulator. By applying the accumulated pressure to the stepped piston of the charging valve device and moving the stepped piston downward, the flow restricting valve is set to the throttle position, the hydraulic fluid discharged from the pump is throttled, and hydraulic pressure is generated. This hydraulic pressure is stored in the emergency accumulator. When the accumulated pressure of the emergency accumulator exceeds the set pressure,
The pressure of the emergency accumulator acting on the stepped piston by the pressure control valve is discharged from the discharge port of the charging valve device to the reservoir, so that the stepped piston moves upward and is set at a position where the flow restriction valve is not throttled, The hydraulic fluid discharged from the pump is not throttled at all, and flows freely toward the booster so that no hydraulic pressure is generated, and the pressure accumulation in the emergency accumulator is completed.

[0011]

In the hydraulic booster disclosed in Japanese Patent Application Laid-Open No. H11-78856, components such as a pressure control valve and a stepped piston of a charging valve device are provided to an emergency accumulator. Is operated to ensure that the hydraulic pressure of the emergency accumulator is sufficiently and sufficiently accumulated. However, even one of these components operates as reliably as possible to accumulate the predetermined hydraulic pressure in the emergency accumulator. It is desirable to build up the pressure more reliably and more fully.

The present invention has been made in view of such circumstances, and an object of the present invention is to make it possible to more reliably operate a charge operation on / off valve for controlling a charge operation of a charging valve device. Accordingly, it is an object of the present invention to provide a hydraulic booster that can more reliably accumulate a predetermined hydraulic pressure in an emergency accumulator.

[0013]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is to provide a hydraulic chamber with a hydraulic pressure which flows from a pump when no input is applied to the power chamber. A hydraulic pressure is generated in the power chamber by restricting the flow of the hydraulic fluid flowing from the pump during the operation to which the input is applied, and the input is boosted and output by the hydraulic pressure of the power chamber. The first position where the flow of the hydraulic fluid flowing from the pump is reduced regardless of the non-operation and the operation and the hydraulic pressure is generated, and the flow of the hydraulic fluid is hardly restricted. A flow restricting means having a throttle valve with a freely flowing second position set, an emergency accumulator for storing a hydraulic pressure generated by the flow restricting means, and a hydraulic pressure of the emergency accumulator being equal to or lower than a set pressure. Is the non- When the hydraulic pressure of the emergency accumulator exceeds a set pressure, the throttle valve of the flow rate limiting means is set to the first position by applying the hydraulic pressure of the emergency accumulator to the flow rate limiting means. Accumulating operation control means for controlling the accumulating operation of the hydraulic pressure to the emergency accumulator by the flow rate limiting means by discharging the hydraulic pressure acting on the means and setting the throttle valve to the second position; In a hydraulic booster comprising an emergency valve means for introducing the hydraulic pressure of the emergency accumulator to the power chamber in an emergency, the accumulator operation control means may be configured so that the hydraulic pressure of the emergency accumulator is equal to or less than a set pressure. When the hydraulic pressure of the emergency accumulator is applied to the flow rate limiting means, and when the hydraulic pressure of the emergency accumulator exceeds a set pressure, the hydraulic pressure of the emergency accumulator A charge-on valve for stopping the action on the amount limiting means, and discharging the hydraulic pressure acting on the flow rate limiting means when the hydraulic pressure of the emergency accumulator exceeds a set pressure; A charge-off valve for stopping discharge of the hydraulic pressure acting on the flow rate restricting means when the hydraulic pressure is equal to or less than a set pressure, wherein at least one of the charge-on valve and the charge-off valve is a ball valve A seat portion on which the ball valve can be attached and detached, and a pressing member for pressing the ball valve in a direction of seating on the seat portion, and a pressing surface of the pressing member for pressing the ball valve has a flat surface. It is characterized by that.

[0014]

In the hydraulic booster according to the present invention, the flow rate of the working fluid to the emergency accumulator is controlled by the flow rate limiting means in accordance with the accumulated pressure of the emergency accumulator. With this, when the accumulated pressure of the emergency accumulator is smaller than the set pressure, a large amount of hydraulic fluid is supplied to the emergency accumulator, and the emergency accumulator is quickly accumulated to the set pressure, and the pressure is increased to the set pressure. The accuracy of the pressure accumulation control is improved.

In this case, since the pressing surface of the pressing member against the ball valve is a flat surface, the pressing of the ball valve by the pressing member is only in the direction in which the seat is seated on the seat portion, that is, only in the axial direction. Therefore, the ball valve does not hit the seat due to eccentricity and seats securely without any gap. In addition, since the pressing member presses the ball valve only in the axial direction, the pressing force applied to the pressing member can be effectively used without loss. Thereby, the opening / closing operation of at least one of the charge-on valve and the charge-off valve composed of the ball valve and the seat portion is performed more reliably, and the emergency accumulator is reliably stored with the set pressure or more. become. Therefore, the start and stop of the pressure accumulation operation for the emergency accumulator are reliably controlled, and the accuracy of the pressure accumulation control for the emergency accumulator to the set pressure is further improved.

Further, the operation of charging the hydraulic pressure to the emergency accumulator is prevented from continuing more than necessary, and unnecessary operation of the pump is prevented, so that the frequency of high pressure and high temperature of the hydraulic fluid is reduced. Less. Therefore, the durability of the pump is improved, and the thermal effect on each component in the hydraulic booster system using the hydraulic booster of the present invention, particularly on rubber parts and resin parts such as seal members is reduced. And the durability of these components also improves. Moreover, the entire hydraulic booster system is less exposed to high temperatures.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. 1A and 1B show an example of an embodiment in which a hydraulic booster according to the present invention is applied to a brake booster, wherein FIG. 1A is a longitudinal sectional view thereof, and FIG. 1B is along the line IB-IB in FIG. It is sectional drawing. In the description of the embodiment of the present invention, the same components as those of the conventional hydraulic brake system shown in FIGS. 3 and 4 will be described using the same reference numerals, but some of them may be omitted. is there.

As shown in FIG. 1A, the brake booster 3 to which the hydraulic booster of this embodiment is applied has a housing 39 including a front housing portion 37 and a rear housing portion 38. The input shaft 16, which is connected to a brake pedal (not shown) via a connecting member 40, penetrates through the rear housing portion 38 in a liquid-tight and slidable manner.
The power piston 24 is provided in the front housing portion 37 in a liquid-tight and slidable manner. The power piston 24 is constantly urged rightward in FIG. 1A by a return spring 42. An output shaft 25 that transmits the output of the power piston 24 to the piston of the master cylinder 4 to operate the piston is fitted and abutted on the front end of the power piston 24. Further, a power chamber 23 is formed in a housing 39 between the front housing section 37 and the rear housing section 38, and the rear surface of the piston portion 24a of the power piston 24 faces the power chamber 23.

Further, a control valve 43 is provided in the front housing section 37 below the power piston 24. The control valve 43 includes a cylindrical valve spool 19 slidably fitted in a hole 44 of the front housing part 37. A first annular groove 10 and a third annular groove 12 are respectively formed on the inner surface of the hole 44 of the front housing part 37, and a second annular groove 11 and a fourth annular groove 13 are formed on the outer peripheral surface of the valve spool 19. Is formed. Further, an axial hole 21 penetrating in the axial direction is formed in the valve spool 19, and a position between the third annular groove 12 and the axial hole 21 is provided at a position facing the third annular groove 12. A first radial hole 20 which is always in communication is provided. Further, the rear end portion 1 of the valve spool 19 extending into the power chamber 23
9 a is provided with a second radial hole 22 communicating between the power chamber 23 and the axial hole 21.

Further, a cylindrical slide valve 33 having a third radial hole 45 is slidably fitted on the outer periphery of the rear end 19a of the valve spool 19 in which the second radial hole 22 is formed. The slide valve 33 is constantly urged rearward (to the right in FIG. 1) by a spring 46, and when not in operation, is brought into contact with a stopper 47 fixed to the rear end of the valve spool 19. I have. At the position where the stopper 47 of the valve spool 19 abuts, the second radial hole 22 and the third radial hole 45 are aligned as shown in the figure, and the axial hole 21 and the power chamber 23 are in the second and third radial directions. Direction hole 2
It communicates via 2,45. Further, when the slide valve 33 moves forward relative to the valve spool 19 against the urging force of the spring 46, the third radial hole 45
Is displaced from the second radial hole 22 so that the communication between the axial hole 21 and the power chamber 23 via the two holes 22 and 45 is cut off.

Further, an axial hole 21 of the valve spool 19 is provided.
Open at the right end of the power chamber 23,
A check valve 48 is provided. The third check valve 48 allows the flow of the working fluid from the axial hole 21 to the power chamber 23, and conversely, the power chamber 23
The flow of the working fluid toward is stopped. The first annular groove 10 is always in communication with the reservoir 8 via the circulation passage 15 and the pipe passage 127. Second annular groove 1
1 is always in communication with the inlet passage 14 and will be described later in detail.
It is connected to a pump 6 as a hydraulic pressure source via a flow rate limiting valve 68 and a pipe passage 94. Further, the third annular groove 12
Is the second annular groove 11 when the brake booster 3 is not operated.
And is communicated with the fourth annular groove 13.
When the brake booster 3 is actuated, it communicates with the second annular groove 11 and is cut off from the fourth annular groove 13. Further, the fourth annular groove 13 is always in communication with the circulation passage 15 connected to the reservoir 8 via the pipe passage 127.

The valve spool 19 is constantly urged rearward by a spring 49. When the valve spool 19 is not operated, its rear end abuts on the rear housing portion 38 as shown in the figure, and is set at a retreat limit position (ie, a non-operation position). Have been. And
In the non-operation position of the valve spool 19, the communication area between the first annular groove 10 and the second annular groove 11 is maximum. Further, a lever support member 50 is fixed to the rear end of the power piston 24. As shown in detail in FIG. 1B, the lever support member 50 projects in a lateral direction orthogonal to the axial direction of the input shaft 16, respectively. A pair of support pins 51, 5 provided
2, one end of each of a pair of levers 17, 18 is swingably supported. As shown in FIG. 1A, the other ends of the levers 17 and 18 are swingably supported by support pins (not shown) protruding from the slide valve 33, respectively. Further, elongated holes 53 and 54 in the longitudinal direction of the levers 17 and 18 are formed near one ends of the levers 17 and 18, respectively.

A cylindrical valve control member 55 is slidably fitted on the input shaft 16. The valve control member 55 is constantly urged leftward by a coil spring 56 contracted between the rear member 16b of the input shaft 16 and the stepped portion of the distal end portion 16a of the input shaft 16 when not operating. 16c. As shown in FIG. 1B, the valve control member 55 has a pair of engaging pins 57 and 58, each of which protrudes in a lateral direction orthogonal to the axial direction of the input shaft 16, and these engaging pins Pins 57 and 58 are long holes 5 of levers 17 and 18, respectively.
It extends through 3,54. These engaging pins 57, 58 are both connected to the long holes 5 of the levers 17, 18.
The inner wall surfaces 3, 54 are engaged with each other when moving in the axial direction.

Further, a travel limiter 59 is provided at the tip 16a of the input shaft 16. The travel limiter 59 is drilled at the tip 16a of the input shaft 16,
A ball valve 62 and a valve seat 63 on which the ball valve 62 can be seated are provided in a passage 61 communicating the chamber 60 and the power chamber 23 formed by fitting the distal end portion 16a into the inner hole 24c of the power piston 24. A normally open on-off valve 65 composed of a spring 64 that constantly urges the ball valve 62 in the direction of the valve seat 63, and a slidably fitted in the same passage 61 to push the ball valve 62 to open the on-off valve 65. And a pressing pin 66 for opening and closing control.

In this travel limiter 59, the valve control member 55 contacts the step 16c and pushes the pressing pin 66 in FIG.
Is pressed to the left, the pressing pin 66
Presses the ball valve 62 to separate from the valve seat 63 and opens the on-off valve 65, whereby the power chamber 23 and the chamber 60 are opened in the axial groove 66 a formed on the outer peripheral surface of the pressing pin 66. It communicates through an on-off valve 65. When the power chamber 23 and the chamber 60 communicate with each other, the input shaft 16
Can be moved relative to the power piston 24 in the axial direction. When the valve control member 55 is not pressing the pressing pin 66, the pressing pin 66 does not press the ball valve 62 at all. Therefore, at this time, the ball valve 62 is seated on the valve seat 63 by the urging force of the spring 64 to close the on-off valve 65, and the power chamber 23 and the chamber 60 are shut off, and the chamber 60 is closed.
Is sealed. When the chamber 60 is sealed as described above, the input shaft 16 cannot move relative to the power piston 24 in the axial direction. Furthermore, in the booster 3 of this example,
A dump valve 36 for controlling the supply of the accumulated pressure of the relief valve 77 and the emergency accumulator 9 to the power chamber 23 is provided.

Each of the springs 42, 46, 49, 52
Are set such that when the input shaft 16 advances during a normal brake operation, the spring 49 first bends, then the spring 42 bends, then the spring 46 bends, and finally the spring 42 bends. Have been. The rear housing part 38 and the connecting member 40
A boot 67, which is made of elastic rubber or the like, and prevents foreign matter from entering the outer peripheral surface of the rear member 16b of the input shaft 16, is provided between them.

The hydraulic booster of this embodiment corresponds to the above-described conventional charging valve 28.
That is, a charging valve device 28 for automatically accumulating pressure in the emergency accumulator 9 is provided separately from the booster 3. That is, as shown in FIG. 2, the charging valve device 28 of the hydraulic booster of this example includes a housing 93 provided separately from the housing of the booster 3, and the emergency accumulator 9 is provided in the housing 93. Is provided.

The housing 93 has a pipe passage 94.
Hydraulic fluid inlet 9 connected to the discharge side of pump 6 via
The working fluid inlet 95 is connected to a passage 96 connected to the inlet passage 14 of the booster 3 and is connected to a passage 6 communicating with the emergency accumulator 9.
9 is connected. A flow restricting valve 68 is provided so as to be located between the hydraulic fluid inlet 95 and the passage 96 and between the hydraulic fluid inlet 95 and the passage 69. The housing 93 is provided with a stepped piston 70 which is provided in a liquid-tight and slidable manner and has a stepped portion 70a. The flow rate limiting valve 68 and the stepped piston 70 constitute a flow rate limiting means of the present invention.

The lower end of the stepped piston 70 is a first valve portion 98 which can be seated on a valve seat 97 formed in the housing 93. The first valve portion 98 is provided with a T-shaped throttle passage 99 which is open to the passage 69 and the lower end of the stepped piston 70. The diameter of the throttle passage 99 is equal to that of the passages 94 and 96.
It is set considerably smaller than. Also, the valve seat 97
Is made of an elastic member such as rubber. The first throttle valve is constituted by the valve seat 97, the first valve portion 98, and the throttle passage 99. A second throttle valve is constituted by the annular groove 100 in which the passage 96 opens and the step portion 70a of the stepped piston 70.

The stepped piston 70 is connected to the spring 7
Due to the spring force of 5, the first valve portion 98 is constantly urged in the direction in which the first valve portion 98 is seated on the valve seat 97 and the step portion 70a is separated from the annular groove 100. Also, the step portion 70 of the stepped piston 70
In a, the fluid pressure in the passage 69 is applied in a direction opposing the spring force of the spring 75. Further, the housing 93 has a chamber 1 in which the upper end of the stepped piston 70 faces.
As described later, the hydraulic pressure of the working fluid introduced into the chamber 101 acts on the stepped piston 70 in the same direction as the spring force of the spring 75 as the control pressure of the throttle valve as described later.

The chamber 101 is provided with a passage 102 and a throttle 8 to be described later.
1. While being connectable to the emergency accumulator 9 through the passage 103, it is also possible to connect to the pipe passage 127 through the passage 102, the throttle 81, the passage 104, the discharge port 105, and the pipe passage 106. , And can be connected to the reservoir 8 via the pipe passage 127. The passages 102 and 104, the discharge port 105, and the pipe passage 106 constitute a control pressure discharge passage.

The passage 102, the passage 103 and the passage 104
A charge operation on / off valve 107 is provided between the two. The charge operation on / off valve 107 is disposed in the housing 93 in a liquid-tight and slidable manner, has a frusto-conical first seat portion 108 at an upper end, and has a frusto-conical second seat portion at a lower end. A cylindrical stepped seat member 110 having a portion 109 and an aperture 81 formed of a small hole in the radial direction, a first ball valve 111 capable of sitting on the first seat portion 108, and a second seat portion 109. 2nd seatable
A ball valve 112, a first spring 114 that constantly biases the first ball valve 111 via the first pressing member 113 in a direction of seating on the first seat portion 108, and a second pressing member 1.
15, the second ball valve 112 is connected to the second seat portion 109.
Spring 116 that is constantly biased in the direction of seating
When the accumulated pressure of the emergency accumulator 9 is smaller than the set pressure as described later, the second ball valve 112 is seated on the second seat portion 109, and when the accumulated pressure of the emergency accumulator 9 reaches the set pressure, the second ball valve An adjusting screw 118 for adjusting the set spring force of the second spring 116 via a retainer 117 so that the 112 is separated from the second seat portion 109, a double nut 119 for fixing the adjusting screw 118 to the housing 93, The first and second ball valves 1 are slidably fitted into the inner holes of the stepped seat member 110.
11 and 112 to the first and second seat portions 108, respectively.
Stem 12 that selectively presses in a direction away from 109
0.

This charge operation on / off valve 107 is
The first ball valve 111 and the first seat portion 108 constitute a charge-on valve, and the second ball valve 112 and the second seat portion 109 constitute a charge-off valve. In the illustrated non-operating state of the charge operation on / off valve 107, the stepped seat member 110 is pressed upward through the second ball valve 112 by the spring force of the second spring 116 and is screwed into the housing 93. Is in contact with
In this state, the second ball valve 112 is
9, the charge-off valve is closed, the first ball valve 111 is pressed by the stem 120, is separated from the first seat portion 108 and the charge-on valve is open,
The accumulated pressure of the emergency accumulator 9 is introduced into the chamber 101. As described later, when the accumulated pressure of the emergency accumulator 9 is introduced into the chamber 101, the operation of charging the emergency accumulator 9 with the hydraulic pressure is performed. The state of the charge operation on / off valve 107 is maintained while the accumulated pressure of the emergency accumulator 9 is smaller than the set pressure. When the accumulated pressure of the emergency accumulator 9 reaches the set pressure, the second ball valve 112
16, the charge-off valve is opened by separating from the second seat portion 109 against the spring force of 16, and the first ball valve 111 is seated on the first seat portion 108 to open the charge-on valve.
The fluid pressure in the chamber 101 is discharged to the reservoir 8. When the fluid pressure in the chamber 101 is discharged to the reservoir 8, the operation of charging the emergency accumulator 9 with the fluid pressure is not performed.

The second ball valve 112 of the second pressing member 115
The contact surface, that is, the pressing surface 115a is a flat surface.
The pressing force by which the pressing member 115 presses the second ball valve 112 acts only in the axial direction (vertical direction in FIG. 2), and does not act in the lateral direction (horizontal direction in FIG. 2) perpendicular to the axial direction. It has become.

The adjusting screw 118 is provided with the retainer 11.
A screw portion 118a is formed on the rear end side opposite to the front end that abuts on 6, and a hexagonal hole 84 is formed on the rear end for fitting a tool for turning the adjustment screw 118. Also,
An O-ring 82 is provided on the tip side of the adjusting screw 118. Then, with the O-ring 82 incorporated in the distal end side, a tool is fitted into the hexagonal hole 84 and turned, whereby the adjusting screw 118 is screwed into the hole of the housing 93 and the nut 11
Lock with 9. As described above, the O-ring 82 is incorporated on the front end side, and the rear end side is screwed into the housing 93, so that the adjustment screw 118 adjusts the spring force of the second spring 116, that is, the valve opening pressure of the second ball valve 112. And the liquid tightness can be improved.

Further, the passage 69 is provided with a check valve 122 which allows only the flow of the working fluid in the direction toward the emergency accumulator 9. Further, the emergency accumulator 9 is connected to the accumulator passage 31 of the booster 3 via a passage 123 and a pipe passage 126, and an alarm switch 124 including a pressure switch for detecting a decrease in the accumulated pressure of the emergency accumulator 9 in the passage 123.
Is provided.

In the brake booster 3 of this embodiment configured as described above, when the brake is not operated, the input shaft 16
And the valve spool 19 of the control valve 43 is in the inoperative position shown. When the pump 6 is not operating, the flow limiting valve 68 and the charge operation on / off valve 107 of the charging valve device 28 are set to the states shown in FIG. 2, respectively. That is, the first valve portion 98 of the flow rate limiting valve 68 is set in the first state in which the step portion 70 a is seated on the valve seat 97 and the step portion 70 a is separated from the annular groove 100, and the second state of the charge operation on / off valve 107 Ball valve 1
12 is seated on the second seat portion 109 and the first ball valve 1
11 is separated from the first seat portion 108. At this time, since the second pressing member 115 is pressing the second ball valve 112 only in the axial direction by the spring force of the second spring, the second ball valve 112 is not eccentric and has a conical second ball valve 112 without any gap.
She is seated on the seat 109.

When the pump 7 is driven by driving the engine 7 in the first state and in a state where the hydraulic pressure of the emergency accumulator 9 is smaller than the set pressure, the hydraulic fluid discharged from the pump 6 passes through the pipe passage 94. It is introduced into the working fluid introduction port 95 of the charging valve device 28. The working fluid introduced into the working fluid introduction port 95 further flows toward the passage 69 through the throttle passage 99 of the stepped piston 70 of the flow restriction valve 68. At this time, since the hydraulic fluid is throttled, a relatively low first hydraulic pressure is generated on the hydraulic fluid inlet 95 side. Due to the first hydraulic pressure, the stepped piston 70 moves slightly upward, the flow restricting valve 68 moves the first valve portion 98 away from the valve seat 97, and moves the step portion 70a of the second throttle valve into the annular groove 100. Communicates slightly to As a result, the hydraulic fluid discharged from the pump 6 passes through the gap between the first valve portion 98 and the valve seat 97, and further communicates between the step portion 70a of the stepped piston 70 and the annular groove 100. Through the passage 96,
It flows into the inlet passage 14 of the booster 3 through 25.

The working fluid flowing into the inlet passage 14 returns to the reservoir 8 again through the second annular groove 11, the first annular groove 10, and the circulation passage 15, that is, circulates and flows. At this time, since the communication area between the first annular groove 10 and the second annular groove 11 is maximized, this circulation flow of the hydraulic fluid is not restricted at all, and the hydraulic pressure is not applied to the second annular groove 11. It does not occur. At the same time, the hydraulic fluid flowing through the passage 96 is throttled by the second throttle valve including the step portion 70a and the annular groove 100, so that a second hydraulic pressure is generated in the passage 69 that is higher than the first hydraulic pressure. 2
The hydraulic pressure flows into the emergency accumulator 9 through the check valve 122, and the emergency accumulator 9 is automatically stored.

The hydraulic pressure accumulated in the emergency accumulator 9 is transmitted to the passage 103, the first ball valve 111 and the first seat portion 1.
08, the axial hole of the cylindrical stepped sheet member 110, the throttle 81 and the passage 102 to be introduced into the chamber 101. Since the hydraulic pressure introduced into the chamber 101 acts downward on the stepped piston 70, the stepped piston 70 generates an upward force generated by the hydraulic pressure of the passage 69 acting on the stepped piston 70. The downward force generated by the hydraulic pressure of the chamber 101 acting downward on the stepped piston 70 and the resultant force of the spring force of the spring 75 are maintained in a balanced state. At this time, the stepped piston 7
In this state of 0, the second throttle valve is set to the second state (corresponding to the first position of the present invention), and the flow of the hydraulic fluid to the booster 3 via the passage 96 is maintained in a state of being restricted. Is done. Therefore, the emergency accumulator 9 continues to accumulate the pressure while the flow of the hydraulic fluid to the booster 3 is restricted.
In this state, the hydraulic pressure of the chamber 101 is slightly lower than the hydraulic pressure of the passage 69 by the amount of the spring 75. In addition, the stepped sheet member 110 slightly moves down against the spring force of the spring 116 due to the liquid pressure of the passage 103, that is, the liquid pressure of the emergency accumulator 9, and the stepped portion contacts the stepped portion of the housing 93. It is kept in the state.

When the hydraulic pressure of the emergency accumulator 9 is smaller than the set pressure and the accumulation of pressure in the emergency accumulator 9 is continued, if the normal brake operation is performed by depressing the brake pedal 2, the input shaft 16 and the valve control are controlled. Member 55
Move forward together. Then, first, the engagement pin 5
7 and 58 are in contact with the side walls of the long holes 53 and 54 and the lever 1
7 and 18 respectively rotate counterclockwise in FIG. 1 around the support pins of the slide valve 33. As a result, the power piston 24 advances, and accordingly, the output shaft 25 advances to push the piston of the master cylinder 4.

When the hydraulic pressure of the master cylinder 4 starts to be generated by the operation of the piston of the master cylinder 4, the power piston 24 almost stops moving forward for the first time. When the input shaft 16 further advances, the levers 17 and 18 turn clockwise in FIG. 1 around the support pins 51 and 52, respectively. Then, the other ends of the levers 17 and 18 are pressed by the valve spool 19 via the slide valve 33, so that the valve spool 19 moves forward. For this reason, the third annular groove 12
And the fourth annular groove 13 are shut off, the gap between the first annular groove 10 and the second annular groove 11 is narrowed, and
The annular groove 11 and the third annular groove 12 communicate with each other. Then, a hydraulic pressure is generated in the second annular groove 11, and this hydraulic pressure is applied to the second annular groove 1.
First to third annular grooves 12, first radial holes 20, axial holes 2
Not only is the power supplied to the power chamber 23 through the first and third check valves, but also the second and third
The power is also supplied to the power chamber 23 through the radial holes 22 and 45. As a result, the power piston 24 further moves forward and boosts the pedaling force of the brake pedal 2 and outputs the same. The output of the power piston 24 further presses the piston of the master cylinder 4 via the output shaft 25, and the master cylinder 4 generates a large hydraulic pressure. The brake is applied by the hydraulic pressure of the master cylinder 4.

At the same time, the hydraulic pressure in the power chamber 23 presses the input shaft 16 to the right, and the force pressing the input shaft 16 and the force acting on the input shaft 16 to the left by the depressing force of the brake pedal 2 increase. It is kept in a balanced state. Thus, the hydraulic pressure corresponding to the depression force of the brake pedal 2 is supplied to the power chamber 23. When the depression of the brake pedal 2 rises and the input shaft 16 advances further, the valve spool 19 also advances further, and the gap between the first annular groove 10 and the second annular groove 11 further decreases (finally). In some cases, this gap becomes zero), and the generated hydraulic pressure increases, so that the hydraulic pressure in the power chamber 23 also increases. Therefore, the output of the power piston 24 also increases, and the master cylinder hydraulic pressure also increases.

When the brake pedal 2 is released when the brake is released, the input shaft 16 moves backward. Then, first, the levers 17 and 18 rotate clockwise about the support pins 51 and 52, and the valve spool 19 moves toward the inoperative position. For this reason, the gap between the first annular groove 10 and the second annular groove 11 is maximized, and the flow of the hydraulic fluid from the pump 6 is not restricted, and the hydraulic pressure generated in the second annular groove 11 Is discharged to the reservoir 8 through the circulation passage 15 and disappears. Further, the second annular groove 11 and the third annular groove 12 are shut off, and the third annular groove 12 and the fourth annular groove 13 communicate with each other.
Then, the hydraulic pressure supplied to the power chamber 23 also increases in the third and second radial holes 45 and 22, the axial hole 21, the first radial hole 20, the third annular groove 12, the fourth annular groove 13, and It is discharged to the reservoir 8 through the circulation passage 15 and disappears. This causes the power piston 24 to retreat toward the inoperative position. The rear end of the valve spool 19 is a rear housing part 38.
The levers 17 and 18 rotate counterclockwise around the support pins of the slide valve 33 when the levers 17 and 18 reach the retreat limit position. As a result, the power piston 24 is in the inoperative position and no output is generated, so that the master cylinder 4 is also inoperative and the brake is released.

When the brake is operated, the depression of the brake pedal 2 becomes large, and the front end of the valve spool 19 comes into contact with a plug 83 that closes the hole 44 of the front housing portion 37.
That is, when the valve spool 19 has a full stroke,
The fluid pressure in the power chamber 23 does not increase any more. That is, the brake booster 3 is at the full load point. If the brake pedal 2 is further depressed even at this full load point,
The valve spool 19 does not advance and the levers 17, 18
Hardly rotates, but only the input shaft 16 moves forward.

As a result, the input shaft 16 is
Of the valve control member 55 against the spring force of. Then, since the valve control member 55 does not press the pressing pin 66, the pressing pin 66 does not press the ball valve 62. Therefore, the ball valve 62 is seated on the valve seat 63,
The on-off valve 65 is closed, and the chamber 60 is sealed. That is, the travel limiter 59 operates. Thus, the force acting on the input shaft 16 by the depression force of the brake pedal 2 is directly applied to the power piston 24. Therefore, after the full load point of the brake booster 3, the output of the brake booster 3 increases by an increase in the input of the input shaft 16.

When the input shaft 16 further advances after the full stroke of the valve spool 19, the lever 1
The slide valve 33 is connected to the spring 46 via the switches 7 and 18.
And advances relatively to the valve spool 19 against the spring force of. Therefore, the retainer 34 provided on the slide valve 33 also moves forward to advance the valve body 35 to open the dump valve 36, and the power chamber 23 communicates with the emergency accumulator 9. However, the emergency accumulator 9
Is the same as the hydraulic pressure of the power chamber 23 at the time of the full load, the hydraulic pressure of the power chamber 23 is the same as the hydraulic pressure at the time of the full load.

Further, if the pump 6 breaks down, no hydraulic pressure is generated in the second annular groove 11 even if both the input shaft 16 and the valve spool 19 move forward, so that no hydraulic pressure is supplied to the power chamber 23 either. Therefore, the brake booster 3 does not perform the boosting action. However, when the input shaft 16 advances further, the slide valve 33 advances relative to the valve spool 19 via the levers 17 and 18 after the valve spool 19 has made a full stroke as described above.
Therefore, first, the third radial hole 45 of the slide valve 33 is set.
Is displaced from the second radial hole 22 of the valve spool 19, and the axial hole 21 through the second and third radial holes 22 and 45.
The communication between the power chamber 23 and the power chamber 23 is blocked by the slide valve 33. When the slide valve 33 further moves forward, the retainer 34 moves the valve body 35 forward, so that the dump valve 36 is opened, and the power chamber 23 communicates with the emergency accumulator 9. Therefore, the hydraulic pressure of the emergency accumulator 9 is supplied to the power chamber 23, and increases until the hydraulic pressure of the power chamber 23 becomes the same as the hydraulic pressure at the full load point. And this power room 23
With the hydraulic pressure of, the brake booster 3 performs a boosting action.
Thus, even if the pump fails, the emergency accumulator 9
While the pressure accumulates in the brake booster 3, the brake booster 3 generates an output of a predetermined magnitude.

When the hydraulic pressure stored in the emergency accumulator 9 reaches the set pressure, the hydraulic pressure introduced into the chamber 101 causes
The second ball valve 112 moves down against the spring force of the spring 116 to separate from the second seat portion 109,
Since the stem 120 and the first ball valve 111 also move downward by the downward movement of the second ball valve 112, the first ball valve 111 moves downward and sits on the first seat portion 108. Therefore, the passage 102 is blocked from the passage 103 and communicated with the passage 104, so that the hydraulic pressure of the emergency accumulator 9 is not introduced into the chamber 101, and
The fluid pressure in the chamber 101 is reduced by the passage 102, the throttle 81, the axial hole of the cylindrical stepped seat member 110, the gap between the second ball valve 112 and the second seat portion 109, the passage 104, and the discharge port 10.
5, is discharged to the reservoir 8 through the pipe passage 106 and the pipe passage 127. Then, the hydraulic pressure in the chamber 101 decreases, and the stepped piston 70 moves upward.

At this time, since the hydraulic fluid in the chamber 101 is throttled by the throttle 81, the hydraulic fluid is slowly discharged to the reservoir 8. Therefore, the upward movement of the stepped piston 70 becomes slow, and the upper end of the stepped piston 70 is
It is difficult to contact the upper end of the housing 93. Room 101
When the hydraulic pressure of the is substantially eliminated, that is, when the atmospheric pressure is reached,
The stepped piston 70 moves further upward, and its step 70
a becomes large, the flow restricting valve 68 is set to the third state (corresponding to the second position of the present invention), and the hydraulic fluid flowing from the passage 69 to the passage 96 is slightly restricted. It is kept in the state. That is, the flow rate of the hydraulic fluid to the booster 3 increases, the hydraulic pressure generated in the passage 69 decreases, and the operation of charging the emergency accumulator 9 with the hydraulic pressure ends. Also, since the fluid pressure in the chamber 101 is lost, the first
The seat force seated on the first seat portion 108 of the ball valve 111 increases, and the first force depends on the spring force of the spring 116.
There is no separation from the seat portion 108.

When the pump 6 is started in a state where the hydraulic pressure of the emergency accumulator 9 is stored at or above the set pressure,
The flow restricting valve 68 is set directly from the first state to the third state, and the working fluid flowing from the passage 69 to the passage 96 is slightly throttled as described above, and most of the hydraulic fluid flows toward the booster 3. In the state where the hydraulic pressure of the emergency accumulator 9 is stored above the set pressure, the brake operation by depressing the brake pedal 2 and the release of the brake operation by releasing the brake pedal 2 are performed in the same manner as described above.

When the hydraulic pressure of the emergency accumulator 9 is consumed and the accumulated pressure of the emergency accumulator 9 decreases, the charge operation on / off valve 107 of the charge operation on / off valve 107 pressed by the second pressing member 115 by the spring force of the spring 116. The two-ball valve 112 moves upward and sits on the second seat portion 109, and the stem 120 moves upward to move the first ball valve 111 upward and separate from the first seat portion 108.
At this time, the second ball valve 112 is pressed only in the axial direction by the second pressing member 115, so that the second ball valve 112 is seated on the second seat portion 109 without a gap without being eccentric. This allows
The hydraulic pressure of the emergency accumulator 9 is again introduced into the chamber 101, the stepped piston 70 moves down again, the gap between the stepped portion 70a and the annular groove 100 is reduced, and the operation flows from the passage 69 to the passage 96. The liquid is again squeezed to the state at the time of accumulating the emergency accumulator 9 described above. Accordingly, the hydraulic pressure of the passage 69, that is, the discharge pressure of the pump 6, increases,
The accumulation of pressure in the emergency accumulator 9 is restarted. In addition, the decrease in the accumulated pressure of the emergency accumulator 9 indicates that the alarm switch 1
24 and is reported to the driver. When the engine stops and the pump 6 stops operating, the pump 6
Is no longer supplied to the hydraulic fluid inlet 95.
Then, the stepped piston 70 moves downward by the spring force of the spring 75, and the first valve portion 98 is seated on the valve seat 97. At this time, since the valve seat 97 is formed by the elastic member, the contact noise is prevented.

According to the brake booster 3 of this example, when the emergency accumulator 9 is performing the automatic pressure accumulation operation, even if the brake operation is performed, the depressing force of the brake pedal 2 is boosted to a predetermined magnitude. Not only can the normal brake be reliably applied, but when the accumulated pressure of the emergency accumulator 9 is equal to or higher than the set pressure, the flow rate of the hydraulic fluid to the booster 3 is increased by the flow rate limiting valve 68 to further increase the normal brake. Can be applied more reliably. As a result, the driver can perform the brake operation without any discomfort.

When the pump 6 is started with the pressure lower than the set pressure of the emergency accumulator 9, the pump 6
The hydraulic fluid discharged from the emergency accumulator 9 is reduced in flow rate by the second throttle valve of the flow rate restricting valve 68 and flows into the emergency accumulator 9, so that the rush pressure of the emergency accumulator 9 is reduced. Therefore, when the pump 6 is started, it is possible to suppress the impact on the emergency accumulator 9 due to the rush pressure. Further, the charge operation on / off valve 107 controls the flow rate limiting valve 6 according to the accumulated pressure of the emergency accumulator 9.
8 controls the flow rate of the working fluid to the emergency accumulator 9, so that when the accumulated pressure of the emergency accumulator 9 is smaller than the set pressure, a large amount of working fluid is sent to the emergency accumulator 9 and the emergency accumulator 9 is supplied. 9 is quickly accumulated to the set pressure, and the accuracy of the accumulation control to this set pressure is improved.

Further, since the pressing surface 115a of the second pressing member 115 against the second ball valve 112 is a flat surface, the second ball valve by the second pressing member 115 urged by the spring force of the second spring 116. The pressing of 112 can be performed only in the axial direction. Therefore, the second ball valve 112 can be seated on the conical second seat portion 109 without a gap without eccentric contact. In addition, since the second pressing member 115 presses the second ball valve 112 only in the axial direction, the spring force of the second spring 116 can be used most effectively without loss at all times. Thus, the opening / closing operation of the charge-off valve including the second ball valve 112 and the second seat portion 109 can be more reliably performed, and the emergency accumulator 9 can reliably store the pressure equal to or higher than the set pressure. Moreover, when the pressure of the emergency accumulator 9 is accumulated to a value equal to or higher than the set pressure, the operation of charging the emergency accumulator 9 with the hydraulic pressure can be reliably terminated. Therefore, the accuracy of the pressure accumulation control to the set pressure is improved.

Further, this prevents the operation of charging the hydraulic pressure to the emergency accumulator 9 from continuing more than necessary, and also prevents unnecessary operation of the pump. Frequency can be reduced. Accordingly, the durability of the pump 6 is improved, and the thermal effect on each component in the hydraulic brake system 1, particularly, rubber or resin components such as a seal member can be reduced. The nature also improves. In addition, exposure of the entire hydraulic brake system 1 to high temperatures can be reduced.

Furthermore, when the working fluid in the chamber 101 is discharged to the reservoir 8 when the accumulated pressure of the emergency accumulator 9 reaches the set pressure, the working fluid is squeezed by the throttle 81 and discharged slowly. The upward movement of the attached piston 70 can be made slow. This makes it difficult for the upper end of the stepped piston 70 to contact the housing 93 at the upper end of the chamber 101. Even if the upper end of the stepped piston 70 contacts the housing 93, the upward movement of the stepped piston 70 does not occur. Since it is slow, there is almost no contact sound.

Further, since the alarm switch 124 detects whether or not the accumulated pressure of the emergency accumulator 9 is the set pressure, the charging valve device 28 is used.
When the emergency accumulator 9 is in an abnormal state where the hydraulic pressure equal to or higher than the set pressure is accumulated even when the pump 6 is operated due to the abnormality of the charging function or the like, the abnormal state can be surely known. In the above-described example, the pressing surface 115 of the second pressing member 115 against the second ball valve 112 is used.
Although a is a flat surface, the pressing surface 113a of the first pressing member 113 against the first ball valve 111 is also flat, and the first pressing member 113 presses the first ball valve 111 with the spring force of the first spring 114. The pressing force may be applied only in the axial direction.

[0059]

As is apparent from the above description, according to the hydraulic booster of the present invention, when the hydraulic pressure of the emergency accumulator is lower than the set pressure, the emergency accumulator is automatically accumulated. Can be. Also, since the flow rate of the working fluid to the emergency accumulator is controlled by the flow rate limiting valve according to the accumulated pressure state of the emergency accumulator, when the accumulated pressure of the emergency accumulator is smaller than the set pressure, a large amount of the working fluid is used for emergency. The emergency accumulator can be fed to the accumulator to quickly accumulate the pressure to the set pressure, and the accuracy of the accumulator control to the set pressure is improved.

Further, since the pressing surface of the pressing member against the ball valve is a flat surface, the ball valve can be securely and securely seated on the seat portion without any contact due to eccentricity. In addition, since the pressing force applied to the pressing member can be used as efficiently as possible without loss, at least one of the charge-on valve and the charge-off valve can be more reliably opened and closed. Thus, the start and stop of the pressure accumulation operation for the emergency accumulator can be reliably controlled, and the accuracy of the pressure accumulation control to the set pressure for the emergency accumulator can be further improved.

Further, since the charging operation of the hydraulic pressure to the emergency accumulator can be prevented from continuing more than necessary and unnecessary operation of the pump can be prevented, the frequency of the high pressure and high temperature of the hydraulic fluid can be reduced. Therefore, the durability of the pump can be improved, and the durability of each component in the hydraulic booster system using the hydraulic booster of the present invention, in particular, the rubber parts and the resin parts such as the seal members are also improved. It is also possible to reduce exposure of the entire hydraulic booster system to high temperatures.

[Brief description of the drawings]

FIG. 1 shows a brake booster to which an example of an embodiment of a hydraulic booster according to the present invention is applied, (a) is a longitudinal sectional view thereof, and (b) is a sectional view taken along line IB-IB in (a). It is sectional drawing which follows.

FIG. 2 is a sectional view showing a charging valve device for the brake booster shown in FIG.

FIG. 3 is a diagram showing an example of a conventional hydraulic brake system.

FIG. 4 is a diagram showing an example of a conventional open center type hydraulic brake booster.

[Explanation of symbols]

1: hydraulic brake system, 2: brake pedal, 3:
Open center type hydraulic brake booster, 4
... Master cylinder, 5 ... Brake cylinder, 6 ... Pump, 8 ... Reservoir, 9 ... Emergency accumulator, 28 ...
Charging valve; charging valve device, 68 ...
Flow restricting valve, 70: stepped piston, 93: housing,
95 ... working fluid inlet, 96 ... passage, 97 ... valve seat, 98 ...
1st valve part, 99 ... throttle passage, 101 ... chamber, 102,10
4,133: passage, 105: outlet, 106: pipe passage, 107: charge operation on / off valve, 108: first
Seat portion, 109: second seat portion, 110: stepped seat member, 111: first ball valve, 112: second ball valve,
113 ... first pressing member, 113a ... first pressing member 113
Pressing surface of the first ball valve 111, 114 ... first spring, 115 ... second pressing member, 115a ... pressing surface of the second pressing member 115 against the second ball valve 112, 11
6 ... second spring, 120 ... stem

Claims (1)

[Claims] 1. An operation that flows from the pump during operation to which an input is applied without generating a hydraulic pressure in the power chamber by allowing the working fluid flowing from the non-operation pump to which no input is applied to flow freely. By reducing the flow of the liquid, a hydraulic pressure is generated in the power chamber, and the input is boosted and output by the hydraulic pressure of the power chamber. Flow restrictor having a throttle valve in which a first position for restricting the flow of the hydraulic fluid flowing from the pump to generate a hydraulic pressure and a second position for freely flowing the hydraulic fluid with almost no restriction are set. Means, an emergency accumulator for storing the hydraulic pressure generated by the flow rate limiting means, and when the hydraulic pressure of the emergency accumulator is equal to or less than a set pressure, the emergency accumulator is caused to act on the flow rate limiting means. hand The throttle valve of the flow rate limiting means is set to the first position, and when the hydraulic pressure of the emergency accumulator exceeds a set pressure, the hydraulic pressure acting on the flow rate limiting means is discharged to reduce the throttle pressure. Accumulator operation control means for controlling the accumulator operation of the hydraulic pressure to the emergency accumulator by the flow rate limiting means by setting the valve to the second position;
An emergency valve means for introducing the hydraulic pressure of the emergency accumulator to the power chamber in an emergency, wherein the pressure accumulating operation control means is configured so that the hydraulic pressure of the emergency accumulator is equal to or less than a set pressure. In this case, the hydraulic pressure of the emergency accumulator is applied to the flow rate restricting means. When the hydraulic pressure of the emergency accumulator exceeds a set pressure, the hydraulic pressure of the emergency accumulator acts on the flow rate limiting means. When the hydraulic pressure of the emergency accumulator exceeds a set pressure, the hydraulic pressure acting on the flow rate restricting means is discharged, and the hydraulic pressure of the emergency accumulator is equal to or less than the set pressure. And a charge-off valve for stopping the discharge of the hydraulic pressure acting on the flow rate restricting means, wherein at least one of the charge-on valve and the charge-off valve is provided. Includes a ball valve, a seat portion on which the ball valve can be attached and detached, and a pressing member that presses the ball valve in a direction in which the ball valve is seated on the seat portion, and presses the pressing member that presses the ball valve. A fluid pressure control device, wherein the surface is a flat surface.