JPH0541105Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a negative pressure booster used in a brake booster, etc., and particularly relates to a negative pressure booster equipped with a reaction disk. be.

(Prior Art) Conventionally, in a brake booster using negative pressure, the brake reaction force is transmitted to the brake pedal by a reaction force means in order to allow the driver to sense the magnitude of the braking force during operation. .

As one of such reaction force means, the
2. Description of the Related Art A reaction disk made of an elastic member is known, as disclosed in Japanese Patent No. 70964 and the like.

This reaction disk is disposed in a recessed part formed at the front end of the valve body of the brake booster. The rear end of the output shaft is in contact with the front surface of this reaction disk, and the front end of a valve plunger connected to the input shaft is opposed to the rear surface of the reaction disk.

When the negative pressure booster operates and the output shaft operates the brake master cylinder, the reaction force is transmitted to the reaction disk via the output shaft. For this reason, the reaction disk deforms elastically according to the magnitude of the reaction force, and uses its elasticity to transmit the reaction force to the valve plunger, which in turn is connected to the brake pedal via an input shaft connected to it. It is designed to transmit reaction force. In this way, the driver can sense the magnitude of the braking force.

(Problem to be solved by the invention) By the way, in a negative pressure booster equipped with such a reaction disk, in order to transmit the reaction force from the output shaft to the valve plunger via the reaction disk, The recessed part in which the reaction disk is disposed has a structure in which it has no choice but to communicate with the valve plunger side. Therefore, when the brake booster is activated, air at atmospheric pressure enters the recessed part on the rear surface of the reaction disk from the valve plunger side.

On the other hand, in such a negative pressure booster, the output shaft may be tilted with respect to the valve body during operation. When the output shaft is tilted, an unbalanced load will be applied to the reaction disk, which will cause the reaction disk and valve body to be partially separated, creating a gap between them. be. Particularly in the early stages of operation, there is no braking effect and no reaction force is applied to the reaction disk, so gaps are likely to occur. When such a gap is created, air that has entered the recessed part on the rear surface of the reaction disk will enter the constant pressure chamber through this gap. This causes a problem in that the airtightness between the constant pressure chamber and the recessed part on the rear surface of the reaction disk is lost, resulting in a loss of output, especially in the early stages of operation.

SUMMARY OF THE PRESENT DEVICE The present invention has been made in view of the above problems, and its object is to provide a negative pressure booster which can reliably maintain airtightness between the reaction disc and the valve body.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention is arranged so as to be movable in and out of the space formed by the front shell and the rear shell, and to airtightly seal the rear shell. a valve body which is slidably penetrated through the valve body; a constant pressure chamber which is connected to the valve body and into which negative pressure is introduced; and a variable pressure chamber into which negative pressure is introduced when not in operation and atmospheric pressure is introduced when in operation. a power piston partitioned into two parts; a valve plunger slidably disposed in an axial through hole bored in the valve body; and a valve plunger connected to the valve plunger and disposed movably in the valve body. an input shaft provided within the valve body;
actuated by the valve plunger to communicate the variable pressure chamber and the constant pressure chamber when not actuated;
a control valve that selectively controls switching so as to isolate the variable pressure chamber and the constant pressure chamber and communicate the variable pressure chamber with the atmosphere when activated; and a recess formed in a front end portion of the valve body facing the constant pressure chamber. an output shaft whose rear end is fitted into the fitting part and whose front end penetrates the front shell and protrudes to the outside, and which is housed in a recess formed in the rear end of the output shaft; In a state in which the recess of the output shaft is slidably fitted into an annular protrusion formed at the bottom of the recessed fitting part of the valve body, the recess is inserted between the valve body and the output shaft and onto the valve plunger. An annular retainer comprising reaction disks interposed to face each other and an annular retainer that prevents the rear end portion of the output shaft from coming out of the recessed fitting portion of the valve body due to the urging force received from the urging means. In the pressure booster, the retainer includes an inner cylindrical part extending in the axial direction and an elastic member fixed to the inner cylindrical part to hold the output shaft on the inner peripheral part of the retainer,
A holding part is formed to maintain the attitude of the output shaft so that it is coaxial with the inner cylindrical part, and an outer cylindrical part that extends in the axial direction concentrically with the inner cylindrical part is formed on the outer peripheral part of the retainer. is formed, and the outer cylindrical portion is fitted into the recessed fitting portion of the valve body to form an alignment portion that aligns the retainer to be coaxial with the valve body. Further, the retainer presses the reaction disk against the front end surface of the valve body via the elastic member and the output shaft by the urging force received from the urging means.

(Function) In the negative pressure booster of the present invention having such a configuration, the retainer is aligned with the valve body by the centering portion thereof, so that the retainer slidably holds the output shaft. The holding part is located coaxially with the valve body. Therefore,
The holding portion of the retainer allows the output shaft to be slidably held so that the output shaft is coaxial with the valve body.

Therefore, even if the output shaft moves during operation, the output shaft is reliably held coaxially with the valve body, and is almost never tilted with respect to the valve body. As a result, the output shaft does not apply an unbalanced load to the reaction disk, so there is no possibility that the reaction disk and valve body become partially separated. This ensures airtightness between the reaction disk and the valve body.

Furthermore, since the reaction disk is pressed against the front end surface of the valve body via the output shaft by the retainer that receives the urging force of the urging means, the airtightness between the reaction disk and the front end surface of the valve body is maintained at the initial stage of operation. Leakage will be reliably prevented.

(Example) Hereinafter, an example of the present invention will be described using the drawings.

FIG. 1 is a longitudinal sectional view showing an embodiment in which a negative pressure booster according to the present invention is applied to a brake booster.

As shown in FIG. 1, the brake booster 1 includes a front shell 2 and a rear shell 3.
are connected, for example, by bayonet connection or the like.

A valve body 4 is disposed so as to pass through the rear shell 3, and the valve body 4 is supported by the rear shell 3 and a seal member 5 in an airtight and slidable manner. Valve body 4 has
A power piston member 6 disposed in the space within both shells 2 and 3 is connected. At the back of this power piston member 6, the shells 2 and 3 and the valve body 4 are connected.
A diaphragm 7 is provided between the two. The power piston member 6 and the diaphragm 7 constitute a power piston 8, and the power piston 8 divides the space within both shells 2 and 3 into a constant pressure chamber 9 and a variable pressure chamber 10.

The valve body 4 is formed with a recessed fitting part 11 that opens into the constant pressure chamber 9, and this recessed fitting part 11 has a stepped shape consisting of a first recessed part 11a with a relatively large diameter and a second recessed part 11b with a small diameter. It is said that At the bottom of the second recess 11b, a constant pressure chamber 9 is located in the center.
A protrusion 4a is formed that protrudes to the side. A first hole 12 that opens into the recessed fitting portion 11 is formed approximately at the center of the protruding portion 4a.
2nd hole 13, 3rd hole 14, 4th hole 15, 5th hole 16, and 6th hole 17 which opens to the atmosphere are bored in this order in the rearward direction (to the right in the figure). .

The valve body 4 is provided with an axial passage 18 that communicates the constant pressure chamber 9 with the fifth hole 16 .

Further, a front end portion of a valve plunger 19 is slidably fitted into the second hole 13 of the valve body 4, and a rear end portion of the valve plunger 19 is fitted into the third hole 14, respectively. An input shaft 20 that is connected to a brake pedal (not shown) is connected to the right end of the valve plunger 19. Valve body 4 has
A radial hole 21 is formed perpendicular to the third hole 14, and a key member 22 is fitted into the valve plunger 19 through the hole 21 so as to be movable relative to the valve plunger 19 in the axial direction. ing. Further, the key member 22 can be moved in the axial direction by the width of the hole 21 (ie, the axial length). The key member 22 also prevents the valve plunger 19 from slipping out of the valve body 4.

Furthermore, a passage 23 opening into the variable pressure chamber 10 is bored in the valve body 4 so as to be perpendicular to the third hole 14 . This passage 23 communicates with the fourth hole 15 via a passage 14a formed in the third hole 14.

A control valve 24 is provided in the sixth hole 17 of the valve body 4.
is provided. The control valve 24 includes a valve body 26 that is attached to the valve body 4 and is constantly biased toward the valve plunger 19 by the elastic force of a spring 25 interposed between the valve body 4 and the input shaft 20, and a valve body 26 that is always biased toward the valve plunger 19. The first valve seat 27 formed on the right end of 19
and a second valve seat 28 formed on the valve body 4. When the valve body 26 is seated on the first valve seat 27 and separated from the second valve seat 28, the control valve 24 communicates between the constant pressure chamber 9 and the variable pressure chamber 10, and connects the variable pressure chamber 10 with the atmosphere. When the valve body 26 is separated from the first valve seat 27 and is seated on the second valve seat 28, the constant pressure chamber 9
Switching control is performed to cut off the communication between the variable pressure chamber 10 and the variable pressure chamber 10, and to communicate the variable pressure chamber 10 with the atmosphere.

The output shaft 2 is disposed within the recessed fitting portion 11 of the valve body 4.
A rear end large diameter portion 9 is provided, and a recess 29a is formed in this rear end large diameter portion. This recess 2
The inner surface of 9a is the recessed fitting part 11 of the valve body 4.
It is slidably fitted into an annular protrusion 4a formed at the bottom of the holder. A reaction disk 30 is housed in the recess 29a of the large diameter rear end of the output shaft 29, located between the annular protrusion 4a of the valve body 4 and the bottom of the recess 29a of the output shaft 29. . Therefore, the reaction disk 30 is connected to the valve plunger 19 via the spacing member 31.
is facing.

Inside the first hole 12 is a reaction disk 30.
and the left end of the valve plunger 19, the spacing member 3
1 is interposed. By appropriately changing the cross-sectional area of the spacing member 31, the boost ratio can be changed even if the cross-sectional area of the valve plunger 19 is kept constant. This makes it possible to use the valve plunger 19 in common for various negative pressure boosters.

A predetermined gap is set between the spacing member 31, the valve plunger 19, and the reaction disk 30.

The output shaft 29 is prevented from being pulled out of the valve body 4 by a retainer 33 which is biased to the right by a return spring 32 which returns the valve body 4 to the inoperative position. As is clear from FIG. 2, this retainer 33 is formed in an annular shape,
Its outer peripheral end is bent forward to form an outer cylindrical portion 3.
3a is formed, and this outer cylindrical portion 33a extends in the axial direction of the valve body 4. Further, the inner peripheral end of the retainer 33 is also bent forward to form an inner cylindrical portion 33b, and this inner cylindrical portion 33b also extends in the axial direction of the valve body 4. That is, these outer and inner cylindrical portions 33
a and 33b are arranged concentrically. Additionally, the inner cylindrical portions 33a and 33b make the retainer 33 relatively strong.
An elastic member 34 made of rubber or the like having an appropriate tightening margin is fixed to the inner cylindrical portion 33b by baking or the like. Further, a hole 33c is bored in the end face of the retainer 33 to communicate the passage 18 of the valve body 4 with the constant pressure chamber 9.

The retainer 33 configured in this manner is provided in the valve body 4 by fitting the outer cylindrical portion 33a into the first recess 11a of the recessed fitting portion 11.
In that case, when the outer cylindrical portion 33a is fitted into the first recess 11a, the valve body 4 and the retainer 3
3 and are located on the same axis. That is, the outer cylindrical portion 33a has a function of aligning the retainer 33 with respect to the valve body 4, and constitutes an alignment portion of the present invention. On the other hand, the inner cylindrical portion 33b
An output shaft 29 passes through the output shaft 29.
is lightly tightened by the extremely weak elasticity of an elastic member 34 provided on the inner cylindrical portion 33b. By this inner cylindrical portion 33b, the output shaft 29 is held in a position coaxial with the inner cylindrical portion 33b, that is, the output shaft 29 is held in a position coaxial with the valve body 4. has been done. That is, the inner cylindrical portion 33b constitutes the holding portion of the present invention.

In addition, in the illustrated non-operating state, the elastic force of the return spring 32 is applied to the large diameter portion of the rear end of the output shaft 29 via the elastic member 34, and the output shaft 29 is lightly pressed toward the valve body 4. ing. Therefore,
Reaction disk 30 is light valve body 4
is crimped to.

The front end of the output shaft 29 is airtightly and slidably supported by a sealing member 35 and is connected to the front shell 2.
It protrudes outward from the front shell 2, and its front end is adapted to interlock with a piston of a master cylinder (not shown) attached to the front shell 2.

The valve body 4 and the power piston 8 connected thereto are normally held in the illustrated inactive position by a return spring 32. In this non-operating state, the key member 22 comes into contact with the inner surface of the rear shell 3, thereby restricting the rightward movement of the valve plunger 19 and holding the valve plunger 19 at the backward limit position. When the input shaft 20 is not in operation,
Both the valve seat 27 and the second valve seat 28 are seated, and the variable pressure chamber 10 is isolated from both the atmosphere and the constant pressure chamber 9. Therefore, during braking, when the valve plunger 19 is actuated by the advancement of the input shaft 20, the valve body 26 and the first valve seat 27 are immediately separated,
The variable pressure chamber 10 and the atmosphere are immediately communicated with each other.

The constant pressure chamber 9 communicates with, for example, an intake manifold of an engine (not shown) via a negative pressure introduction pipe 36 attached to the front shell 2. Therefore, negative pressure is always introduced into the constant pressure chamber 9.

Next, the operation of this embodiment will be explained.

When the brake booster 1 is in the non-operating position shown in the figure, the pressure in the variable pressure chamber 10 is slightly higher than the pressure in the constant pressure chamber 9, and the pressure is approximately balanced with the elastic force of the return spring 32. It's summery.

When the brake pedal is depressed during braking, the input shaft 20 moves forward toward the valve body 4. As the input shaft 20 moves forward, the valve plunger 1
9 moves forward with respect to the key member 22 and the valve body 4. When the valve plunger 19 moves forward, the first valve seat 27 separates from the valve body 26 of the control valve 24 .
Therefore, air at atmospheric pressure enters the sixth hole 17 and the valve body 26.
and the first valve seat 27, the fourth hole 15, the third
It flows into the variable pressure chamber 10 through the passage 14a of the hole 14 and the passage 23. Furthermore, the air that has flowed into the variable pressure chamber 10 leaks into the first hole 12 through the gap between the valve body 4 and the valve plunger 19 in the second hole 13, and this leaked air flows into the reaction disk 30.
It comes to act on the rear end surface of. Therefore, the reaction disk 30 is pressed forward, but since the reaction disk 30 is pressed in the direction of the valve body 4 by the output shaft 29, it hardly moves. Therefore, airtightness is reliably maintained between the reaction disk 30 and the valve body 4 at the initial stage of operation.

Moreover, since the output shaft 29 is held in the axial direction by the inner cylindrical portion 33b of the retainer 33, the output shaft 29 does not tilt with respect to the valve body 4. Therefore, the output shaft 29
Since an unbalanced load due to the tilting of the valve body 4 is not applied to the reaction disk 30, airtightness can be maintained even more reliably between the reaction disk 30 and the valve body 4.

As a result, air leaks to the constant pressure chamber 9 side and no output loss occurs.

The air flowing into the variable pressure chamber 10 operates the power piston 8 and moves the valve body 4 forward, so the brake booster 1 generates an output via the output shaft 29 to operate the piston of the master cylinder. However, due to various resistances in the brake circuit after the master cylinder, no braking effect occurs yet. At the beginning of such operation,
Predetermined gaps are formed between the spacing member 31 and the reaction disk 30 and between the spacing member 31 and the valve plunger 19, so that the valve plunger 19 and the reaction disk 30 can be connected via the spacing member 31. There is no engagement.

Once the aforementioned resistances have been overcome, braking can begin. At this point, the spacing between the reaction disk 30, the spacing member 31 and the valve plunger 19 is absorbed, so that the reaction disk 30 and the valve plunger 19 are
1. Therefore, the reaction force due to braking is applied to the output shaft 29 and the reaction disk 3.
0 is transmitted to the driver via the spacing member 31, the valve plunger 19 and the input shaft 20. By this time, the output has already become quite large compared to the input, and a so-called jumping effect takes place. In that case, there is no variation in the jumping load, so the jumping characteristics become stable.

When the brake pedal is released to release the brake, the input shaft 20, the valve plunger 19, and the key member 22 are all moved rearward with respect to the valve body 4 until the key member 22 abuts the rear end wall of the hole 21.
In other words, move to the right. As the valve plunger 19 retreats, the first valve seat 27 comes into contact with the valve body 26 to shut off the variable pressure chamber 10 and the atmosphere, and the valve body 26
is separated from the second valve seat 28 and the variable pressure chamber 10 and constant pressure chamber 9
communicate with. As a result, the air in the variable pressure chamber 10 flows into the constant pressure chamber 9 and further flows into the intake manifold through the negative pressure introduction pipe 36. In that case,
The valve plunger 19 is at the most retracted position with respect to the valve body 4, and the gap between the valve body 26 and the second valve seat 28 is maximized. Therefore, the air in the variable pressure chamber 10 will flow quickly, and the valve body 4 and power piston 8 will quickly retreat due to the elastic force of the spring 32.

When the key member 22 comes into contact with the inner surface of the rear shell 3, the valve plunger 19 and the key member 22 no longer move back, but the valve body 4 continues to move back further. When the second valve seat 28 comes into contact with the valve body 26, the air in the variable pressure chamber 10 will no longer flow out toward the constant pressure chamber 9, so the power piston 8 will no longer retreat and will be at the backward limit position. The valve body 4 and the valve plunger 19 are thus in the initial inoperative position shown.

Note that the present invention is not limited to the above-described embodiments, and various design changes are possible.

For example, in the embodiment described above, the reaction disk 30 and the valve plunger 19 are used as a negative pressure booster.
Although the explanation is given using a negative pressure booster 1 in which a gap member 31 is provided between the two, the present invention can also be applied to a negative pressure booster that does not use such a gap member 31. Similarly, it is also possible to apply the present invention to a type of negative pressure booster in which the valve body 26 and the second valve seat 28 are separated from each other during non-operation so that the variable pressure chamber 10 and the atmosphere communicate with each other.

Further, in the above embodiment, the valve body 4 and the power piston member 6 are formed separately, but the present invention can also be applied to a negative pressure booster in which these are formed integrally.

Further, although the above-mentioned embodiment describes the case where the negative pressure booster of the present invention is applied to a brake booster, the present invention can also be applied to other boosters such as a clutch booster. Can be applied.

(Effect of the invention) As is clear from the above explanation, according to the negative pressure booster of the invention, the retainer is positioned coaxially with the valve body by the centering part of the retainer, and the retainer is held. Since the output shaft is held coaxially with the valve body by the portion, the output shaft is reliably held coaxially with the valve body. Therefore, the output shaft does not tilt with respect to the valve body during operation, and the airtightness between the reaction disk and the valve body can reliably prevent leakage.

Furthermore, since the reaction disk is pressed against the front end surface of the valve body via the output shaft by the retainer that receives the urging force of the urging means, airtightness between the reaction disk and the front end surface of the valve body is maintained at the initial stage of operation. Leakage can be prevented even more reliably.

Further, since it is sufficient to simply form a holding portion for holding the attitude of the output shaft in the retainer, it is possible to achieve the effect that the attitude of the output shaft can be controlled extremely easily.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment in which a negative pressure booster according to the present invention is applied to a brake booster, and FIG. 2 is a perspective view of a retainer used in this booster. 1... Brake booster (negative pressure booster), 2
...Front shell, 3...Rear shell, 4...
Valve body, 9...constant pressure chamber, 10...variable pressure chamber,
19... Valve plunger, 20... Input shaft, 24...
. . . Control valve, 29 .

Claims (1)

[Claims for Utility Model Registration] A valve body that is arranged to be movable forward and backward in a space formed by a front shell and a rear shell, and that penetrates the rear shell in an airtight and slidable manner, and is connected to this valve body. and a power piston that divides the space into a constant pressure chamber into which negative pressure is introduced and a variable pressure chamber into which negative pressure is introduced when not operating and atmospheric pressure is introduced when operating, and a power piston that is bored in the valve body. a valve plunger slidably disposed in an axial through hole; an input shaft connected to the valve plunger and disposed so as to be movable in the valve body; selectively operated by a plunger to communicate the variable pressure chamber and the constant pressure chamber when not in operation, and to block the variable pressure chamber and the constant pressure chamber and to communicate the variable pressure chamber with the atmosphere when in operation; a control valve that controls switching to a control valve, a rear end portion of which is fitted into a recessed fitting portion formed at a front end portion of the valve body facing the constant pressure chamber, and a front end portion of which protrudes to the outside through the front shell; and an output shaft that is housed in a recess formed at a rear end of the output shaft, and the recess of the output shaft slides on an annular protrusion formed at the bottom of the recessed fitting portion of the valve body. In a freely fitted state, a reaction disk interposed between the valve body and the output shaft and facing the valve plunger, and a biasing force received from the biasing means push the rear end of the output shaft. an annular retainer that prevents the valve body from coming out of the recessed fitting part of the valve body; an inner cylindrical part extending in the axial direction; an elastic member fixed to the retainer to hold the output shaft; a holding part is formed to hold the output shaft in a coaxial direction with the inner cylindrical part; an outer cylindrical portion extending in the axial direction is formed concentrically with the inner cylindrical portion, and
The outer cylindrical portion is fitted into the recessed fitting portion of the valve body to form an alignment portion that aligns the retainer coaxially with the valve body, and further includes a centering portion that aligns the retainer coaxially with the valve body. A negative pressure booster characterized in that the retainer presses the reaction disk against the front end surface of the valve body via the elastic member and the output shaft due to the biasing force received.