JPH0345457A - Fluid pressure booster - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION A0 Object of the Invention (1) Industrial Application Field The present invention relates to a fluid pressure booster for boosting a master cylinder that operates the brakes, clutches, etc. of an automobile using fluid pressure. .

(2) Prior Art Conventionally, as a fluid pressure booster, a booster body is housed in a booster body and a boost chamber is defined in the booster body. a booster piston that operates the booster piston; a valve piston that is slidably housed in the booster piston and is connected to the operating member; A control valve equipped with a control valve for controlling communication and isolation between the boost chamber, the fluid pressure source, and the fluid tank is known, for example, as disclosed in Japanese Patent Laid-Open No. 62-265066. There is.

(3) Problems to be Solved by the Invention In the conventional booster as described above, the booster piston follows the movement of the valve piston connected to the operating member. An equivalent stroke is required, which makes it difficult to make it compact in the axial direction.

The present invention has been made in view of the above circumstances, and is capable of applying fluid pressure to a master cylinder as an operating pressure according to the movement of an operating member within a limited stroke range.
The object is to provide a compact fluid pressure booster.

B1 Structure of the Invention (1) Means for Solving the Problems In order to achieve the above object, the present invention provides a booster main body, and a booster main body that is housed in the booster main body so as to be movable back and forth, and between the rear surface of the master piston of the master cylinder. A control piston that defines a boost chamber, and this control piston can move forward and backward.
A reaction force chamber is defined between the valve piston, which is housed in the control piston and whose front surface communicates with the boost chamber, and which is also housed in the control piston so as to be movable back and forth, is connected to the operating member, and defines a reaction force chamber between the valve piston and the rear surface of the valve piston. A force piston, a stroke accumulator that communicates a pressure accumulation chamber with a reaction force chamber, and a control piston and a valve piston that intervene in the flow path between the boost chamber and the fluid pressure source, and close when the valve piston retreats and move forward. and an outlet valve configured between the control piston and the valve piston to intervene in the flow path between the boost chamber and the fluid tank, and which opens when the valve piston moves backward and closes when the valve piston moves forward. It is characterized by

(2) Effect In the above configuration, when the reaction piston is moved forward by the operating member, fluid pressure from the fluid pressure source is supplied to the boost chamber in response to the movement of the reaction piston, thereby boosting the master piston. I can do it.

That is, the fluid pressure of the stroke accumulator generated in the reaction chamber in response to the advance of the reaction piston pushes the valve piston in the forward direction, and the fluid pressure in the boost chamber pushes the valve piston in the backward direction. The valve piston opens and closes the inlet and outlet valves to balance the pressure in the boost chamber.

Additionally, the control piston is normally held in a retracted position by the pressure in the boost chamber, but can move forward together with the operating member to actuate the master piston in the event of a failure of the fluid pressure source.

(3) Examples An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, a fluid pressure booster B is connected to the rear of a brake master cylinder M of an automobile.

The cylinder body 4 of the master cylinder M has a cylinder hole 5 with a closed front end, and the cylinder hole 5 has a front master piston 7f defining a front hydraulic chamber 6f between the cylinder hole 5 and the front end wall thereof. A rear master piston 7r defining a rear hydraulic chamber 6r between the front master piston 7f and the front master piston 7f is slidably fitted. In the front hydraulic chamber 6f, there is a front return spring 8f that urges the front master piston 7r in the backward direction.
However, the rear hydraulic chambers 6r each house a rear return spring 8r that biases the rear master piston 7r in the backward direction. Therefore, if the rear master piston 7r is pushed forward, the front master piston 7f is also advanced while compressing both return springs 8f8r, and the front and rear hydraulic chambers 6f, 6
By reducing the volume of the hydraulic pressure chambers 6f and 6r, the braking oil pressure from the output boats 9f and 9r can be output, thereby operating the corresponding wheel brakes 10a and 10b.

The front end of a booster main body 11 of the booster B is fitted and connected to the outer periphery of the rear end of the cylinder main body 4, and the front and rear pairs of sleeves 13.1 are inserted into the cylinder hole 12 of the booster main body 11.
4 is fitted.

The control piston 1 is provided on the inner circumference of these sleeves 13, 14.
5 is fitted to be slidable in the front and rear direction, and this control piston 1
A boost chamber 16 is defined between the rear master piston 5 and the rear master piston 7r.

The retraction limit of the control piston 15 is determined by a flange 17 formed on the outer periphery of the intermediate portion of the piston 15 at a stopper ring 18 held between the rear end of the booster body 11 and the sleeve 14.
It is regulated by coming into contact with. This control piston 15
Usually, the output rod 15a is provided at the front end of the rear master piston 7r and faces the rear end of the rear master piston 7r with a small gap therebetween.

Further, the control piston 15 has its rear end protruding from the rear end wall of the booster main body 11, and the control piston 1
A set spring 20 is provided to hold the motor 5 at the backward limit.

Further, a valve piston 22 and a reaction piston 23 are slidably fitted in the cylinder hole 21 of the control piston 15 in a lined up front and rear. connected via.

A guide hole 24 and a guide shaft 25 are provided on opposing surfaces of the valve piston 22 and the reaction piston 23, respectively, and the guide shaft 25 is provided with a long hole 26 that is long in the axial direction. At the same time, a pin 27 passing through the elongated hole 26 is fixed to the rear end of the valve piston 22. A return spring 28 is provided between the pistons 22 and 23 to urge them apart. Therefore, both pistons 22 and 23 are held at a position with the maximum distance between them, where the pin 27 abuts the front end wall of the elongated hole 26 during normal times.

The front part of the valve piston 22 is an elongated ring-shaped valve part 22a, and this valve part 22a is fitted into a sleeve-shaped valve chamber body 29 fixed to the center of the control piston 15. .

When the valve piston 22 moves forward by a certain stroke relative to the control piston 15, the shoulder 22b of the valve piston 22 touches the valve chamber body 2.
It comes into contact with the rear end of 9.

A spring chamber 30 is formed within the control piston 15 and faces the front end surface of the valve portion 22a.
A return spring 31 is housed therein, which urges 2 in the backward direction. The set load of the return spring 31 is set to be weaker than that of the return spring 28, and the spring chamber 30 is always in communication with the boost chamber 16 through the through hole 32 of the control piston 15.

The backward limit of the reaction piston 23 is regulated by the rear end coming into contact with a stopper ring 33 that is locked to the rear end of the control piston 15 .

A sealing member 34 that closely contacts the outer periphery of the intermediate portion of the control piston 15 is attached to the sleeve 14, and this sealing member 3
Attached to the control piston 15 are sealing elements 35, 36 that are in close contact with the inner circumference of the sleeve 13, 14 at the front and rear of the sleeve. Furthermore, a sealing member 37 that is in close contact with the outer peripheral surface of the control piston 15 is attached to the rear end wall of the cylinder body 11.

An inlet chamber 38 is defined between the seal members 34 and 35, an outlet chamber 39 is defined between the seal members 34 and 36, and a relay chamber 40 is defined between the seal members 36 and 37.

The inlet chamber 38 communicates with the discharge side of a hydraulic pump 42 driven by an electric motor 41 via a first oil passage, and a hydraulic power source accumulator 43 is connected to the first oil passage L1. The hydraulic pump 42 and the hydraulic power source accumulator 43 constitute a fluid pressure a54.

Further, the outlet chamber 39 communicates with an oil tank 44 as a fluid tank via a second oil passage L2, and the relay chamber 40 communicates with a pressure accumulation chamber 46 of a stroke accumulator 45 via a third oil passage L3.

Seal members 47 and 48 that are in close contact with the inner peripheral surface of the control piston 15 are respectively attached to the valve piston 22 and the reaction piston 23, and a reaction chamber 49 is defined between the seal members 47 and 48. . This reaction force chamber 49 communicates with the relay chamber 40 via a through hole 50.

Between the valve portion 22a and the valve chamber body 29, an inlet valve 51, an outlet valve 52, and an on-off valve 53 are arranged in order from the front.

The inlet valve 51 opens and closes the gap between the inlet chamber 38 and the spring chamber 30, and thus the boost chamber 16, and is closed when the valve piston 22 is at its backward limit, and opened when the valve piston 22 moves forward.

The outlet valve 52 opens and closes the gap between the outlet chamber 39 and the spring chamber 30, and is opened when the valve piston 22 is at its backward limit, and closed when the valve piston 22 moves forward.

The on-off valve 53 opens and closes the space between the outlet chamber 39 and the reaction force chamber 49, and is opened when the valve piston 22 is at its backward limit, and closed when the valve piston 22 moves forward.

Therefore, the opening/closing timing of the three valves 51, 52, and 53 is such that when the valve piston 22 moves forward from the retraction limit, the opening/closing valve 53 closes first, then the exit valve 52 closes, and finally the opening/closing valve 52 closes. Inlet valve 51 is set to open.

The stroke accumulator 45 includes a stepped cylindrical accumulator body 55 and an accumulator body 55.
A first piston 56 that is slidably fitted into the small diameter portion 55a of the accumulator body 55 to define the pressure accumulation chamber 46, and a plurality of second pistons 57 that are housed in series in the large diameter portion 55b of the accumulator body 55. ．． 57□57n, and each second piston 57. ,57
It consists of a plurality of springs 5B+, 58□, and 58n, which respectively spring 57n toward the first piston 56, and the second piston 57 adjacent to the first piston 56 is integrally connected to the first piston 56. , or placed in an abutting relationship. Spring 58. ．． 58□58n are set so that the spring constant increases in that order.

Also, the second piston 57. ．． A cushioning rubber 60. ．． 60. ．． 60n is interposed with some play in the axial direction.

An emergency control valve 6■ is connected to fourth to sixth oil passages L4 to L6 that are connected to the boost chamber 16, the stroke accumulator 45, and the oil pressure source accumulator 43, respectively.

The emergency control valve 61 includes a cylindrical valve surface 62, a piston 64 that is slidably fitted into the valve surface 62 and defines an oil chamber 63 at both bottoms, and a piston 64 that is fitted and fixed to the valve surface 62. 64
A valve seat body 67 with an oil chamber 65 at both bottoms is provided between the valve seat body 67 and an annular oil chamber 66 formed around the outer periphery of the valve seat body 67. In the oil chamber 63, 65, 66, the fourth oil chamber. 5th and 6th
Oil passages L4+LS and Lll are connected to each other.

The piston 64 is provided with a valve chamber 68 that communicates with the oil chamber 65 and a valve hole 69 that communicates the valve chamber 68 with the oil chamber 63. The valve chamber 68 has a relief valve 70 that opens and closes the valve hole 69. and a relief spring 71 that biases the relief valve 70 in the closing direction.

Further, the valve seat body 67 is provided with a valve chamber 72 that communicates with the oil chamber 65 and a valve hole 73 that communicates between this valve chamber 72 and the oil chamber 66 at the other end. A shutoff valve 74, a pressure receiving element 75, and a shutoff valve 7 via this pressure receiving element 75.
A valve spring 76 that urges the valve 4 in the closing direction is housed therein.

Furthermore, a pusher 77 that can come into contact with the pressure receiver 75 is fixed to the piston 64, and a return spring 78 that biases the pusher 77 in a direction away from the pressure receiver 75 is provided between the pusher 77 and the valve seat body 67. It will be reduced to .

Next, the operation of this embodiment will be explained. .

First, a case where the fluid pressure is f1.54, that is, the hydraulic pump 42 and the hydraulic power source accumulator 43 are functioning normally will be described.

In the inactive state of the brake pedal 1, as shown in FIG. Each is held at a predetermined retraction limit by a force. When the valve piston 22 is at the retraction limit, the inlet valve 51 is closed and the outlet valve 5 is closed, as described above.
2 is open, and the on-off valve 53 is in the open state, so the hydraulic pressure of the hydraulic source accumulator 43 is introduced into the inlet chamber 38 via the first oil path L1, and the inlet valve 51 enters the liquid chamber 3
I was put on standby at 8.

The boost chamber 16 includes a through hole 32, a spring chamber 30, and an outlet valve 52.
The master pistons 7f and 7r are in communication with the oil tank 44 via the outlet chamber 39 and the oil tank 44 via the second oil passage L2, respectively, so that the master pistons 7f and 7r can each occupy the retracted position.

Moreover, since the pressure accumulation chamber 46 of the stroke accumulator 45 communicates with the outlet chamber 39 via the third oil passage L3, the relay chamber 40, the reaction force chamber 49, and the on-off valve 53, this chamber is also at atmospheric pressure.

On the other hand, in the emergency control valve 61, the hydraulic power source accumulator 43
The hydraulic pressure is introduced into the oil chamber 63 through the sixth oil passage, and the piston 64 is pressed toward the valve seat body 67 by the hydraulic pressure.
The pusher 77 holds the cutoff valve 74 in the closed position via the pressure receiver 75. When the discharge pressure of the hydraulic pump 42 exceeds a predetermined value, the relief valve 7o opens to release excess hydraulic pressure from the valve hole 69 to the oil chamber 68. The hydraulic pressure released in the oil chamber 68 is guided to the fifth oil path and then to the third oil path, so that it is eventually released to the oil tank 44.

Now, in order to operate the wheel brakes loa and 10b,
When the brake pedal 1 is depressed, the punch rod 2, the reaction piston 23, the return spring 28, and the valve piston 22 move forward (leftward movement in FIG. 1) all at once, and the valve chamber body 29 of the valve portion 22a moves forward.
As the vehicle moves forward, first the on-off valve 53 closes, then the Yamaguchi valve 52 closes, and finally the inlet valve 51 opens. By opening the artificial valve 51, the inlet chamber 38 and the boost chamber 16 are communicated with each other, and the hydraulic pressure waiting in the inlet chamber 38 is transferred to the boost chamber 1.
6 will be introduced. As a result, the master piston 7r receives hydraulic pressure on its back surface and moves forward, so that hydraulic pressure is output from the output boats 9f and 9r as described above, and the wheel brake 1
Activate 0a and 10b.

Furthermore, since the hydraulic pressure introduced into the boost chamber 16 also acts on the front surface of the control piston 15, the control piston 15 is still held at its original retraction limit due to the rearward pressing force due to the hydraulic pressure and the elastic force of the set spring 20. Ru.

Furthermore, the hydraulic pressure introduced into the boost chamber 16 is transmitted to the spring chamber 30 and acts on the front surface of the valve portion 22a, so that the valve piston 22a
It also generates a reaction force that tries to push back backwards.

As the brake pedal 1 is further depressed, the reaction piston 23 compresses the return spring 28 and moves forward while contracting the volume of the reaction chamber 49 in front of it, but after the on-off valve 53 is closed. In this case, the reaction force chamber 49 is in a sealed state. Therefore, as the reaction piston 23 continues to move forward, hydraulic oil is sent from the reaction chamber 49 to the third oil path and then to the pressure accumulation chamber 46 of the stroke accumulator 45, and the stroke accumulator The hydraulic pressure generated in the pressure accumulation chamber 45 is transmitted to the reaction force chamber 49.

As a result, the valve piston 22 receives the reaction force from the stroke accumulator 45 and the pressing force from the return spring 28 at the same time and tries to move forward, but in the spring chamber 30, the hydraulic pressure in the boost chamber 16 pushes the valve piston 22 backward. Since the valve piston 22 is pressed, the valve piston 22 moves back and forth so that the pressing forces before and after the valve piston 22 are balanced, thereby controlling the opening and closing of the inlet valve 51 and the outlet valve 52. In addition, the reaction force from the stroke accumulator 45 and the repulsion force from the return spring 28 act on the reaction piston 23, so that as the amount of depression of the brake pedal l increases,
In other words, as the oil pressure in the boost chamber 16 increases, a reaction force that increases according to the spring characteristics of the stroke accumulator 45 and the return spring 28 acts, and the driver senses this as a braking feeling.

By the way, in the stroke accumulator 43, when the first piston 56 operates in a direction to expand the volume of the pressure accumulation chamber 46 as the amount of oil introduced into the pressure accumulation chamber 46 increases, the spring 581 with the minimum spring constant is first activated by the second piston 571. The cushioning rubber 60. is compressed and the second piston 57. comes into contact with the second piston 572 of the next stage and pushes it. Thereafter, the spring 58□, the buffer rubber 60□, the spring 58n1, and the buffer rubber 60n are sequentially compressed by the same action, so that the spring characteristics of the stroke accumulator 45 become as shown in FIG. 2. That is, the spring force increases in a quadratic curve as the displacement amount of the first piston 56 increases.

According to such spring characteristics, the reaction force is gradually increased at the beginning of the depression of the brake pedal 1 to improve braking controllability, and the reaction force is smoothly and rapidly increased at the later stage of the depression, thereby impairing the feeling of braking. This makes it possible to suppress an increase in the amount of depression.

Incidentally, such an effect can be achieved by using a plurality of springs 58. ．． 5 days □, 5
The same result can be obtained no matter what order 8n is arranged.

Next, a case will be described in which a failure occurs in the oil pressure 1g54 and the oil pressure is not supplied to the first oil path.

When the brake pedal 1 is depressed in such a case, the bushing rod 2, the reaction piston 23, the return spring 28, and the valve piston 22 move forward all at once, and the shoulder 22b of the valve piston 22 touches the rear end of the valve chamber body 29. comes into contact with.

The control piston 15 with the valve chamber body 29 has a relatively large sliding resistance due to the friction of the seal members 35, 36 attached to its outer periphery and the seal member 37 attached to the booster body 11, and also has a set spring. 20, the shoulder portion 22b does not move when it first comes into contact with the valve chamber body 29.

Therefore, according to the subsequent advancement of the reaction piston 23,
As the return spring 28 is compressed, the reaction force chamber 49 is pressurized, and a portion of the oil in the pressure chamber 49 is transferred to the stroke accumulator 45.
is pumped to.

The forward force applied to the valve piston 22 by the hydraulic pressure of the reaction force chamber 49 causes the sliding resistance of the control piston 15 and the set spring 20.
When the force is overcome, the control piston 15 also begins to move forward, and as the control piston 15 moves forward, the volume of the relay chamber 40 between the seal members 36 and 37 is expanded, and negative pressure is generated in the chamber 40.
Oil in the reaction force chamber 49 is sucked into the relay chamber 40.

When the control piston 15 moves further forward, oil in the boost chamber 16 is sucked into the relay chamber 40 through the oil passage. Therefore, no negative pressure is generated in the relay chamber 40 that would prevent the control piston 15 from moving forward.

When oil flows from the reaction force chamber 49 to the stroke accumulator 45 as described above, the compression deformation of the return spring 28 progresses,
Finally, the shoulder 23a of the reaction piston 23 is connected to the valve piston 22.
It comes into contact with the rear end of the machine and pushes it directly.

In this way, the reaction piston 23 and the valve piston 2 are finally
2 and the control piston 15 move forward together to pressurize the boost chamber 16. However, in the emergency control valve 61, the piston 64 loses the closing force of the shutoff valve 74 due to hydraulic pressure, so the oil in the boost chamber 16 Further, the oil is also supplied to the relay chamber 40 whose volume is being expanded through the fourth oil passage 1, the valve hole 73, the oil chamber 65, the fifth oil passage, and the third oil passage. Accordingly, the output rod 15a of the control piston 15 comes into contact with the rear end of the rear master piston 7' and can mechanically move it forward.Therefore, the control piston 15 has a larger diameter than the rear master piston 7r. Also, the movement of the flilJ control piston 15 can be directly transmitted to the rear master piston 7r without being accelerated by the oil in the boost chamber 16, and the negative pressure generation in the inlet chamber 38 and relay chamber 40 can be actively generated. Therefore, the forward movement of the control piston 15 can be easily performed.

C9 Effects of the Invention As described above, according to the present invention, it is possible to generate fluid pressure in the boost chamber according to the amount of advance of the reaction piston by the operating member within a limited stroke range. Together with the concentric arrangement of the reaction pistons, the booster can be made more compact. Moreover, since the fluid pressure generated in the stroke accumulator is transmitted to the reaction force chamber, there is no need to install a large reaction force spring, which can only contribute to making the booster more compact. Rather, the stroke of the operating member can be freely set by controlling the reaction force generated in the reaction force chamber by selecting the characteristics of the stroke accumulator.

Additionally, in the event of a failure of the fluid pressure source, the control piston can be advanced by the operating member to mechanically actuate the master piston.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; FIG. 1 is a longitudinal sectional side view of a fluid pressure booster, and FIG. 2 is a characteristic diagram of a stroke accumulator. B... Booster, M... Master cylinder... Brake pedal as an operating member, 11... Booster body, 12... Cylinder hole, 15... Control piston, 1
6... Boost chamber, 22... Valve piston, 23...
・Reaction force piston, 38... Population chamber, 39... Outlet chamber, 44... Oil tank as a fluid tank, 45...
Stroke accumulator, 46... Pressure accumulation chamber, 49.
... Reaction force chamber, 51 ... Population valve, 52 ... Outlet valve, 5
4...Fluid pressure source

Claims (1)

[Claims] a booster body; a control piston that is housed in the booster body so as to be movable back and forth and defines a boost chamber between the rear surface of the master piston of the master cylinder; A reaction piston, which is also accommodated in the control piston so as to be movable back and forth and is connected to the operating member, and defines a reaction chamber between the valve piston and the rear surface of the valve piston; a stroke accumulator that communicates the pressure accumulation chamber; an inlet valve configured between the control piston and the valve piston to intervene in the flow path between the boost chamber and the fluid pressure source; the inlet valve closes when the valve piston moves backward and opens when the valve piston moves forward; A fluid pressure system, characterized by comprising an outlet valve configured between the control piston and the valve piston to intervene in the flow path between the boost chamber and the fluid tank, and which opens when the valve piston retreats and closes when the valve piston moves forward. booster.