JPH11278248A - Pneumatic booster - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To suppress the occurrence of hysteresis in the input / output characteristics, improve the responsiveness at the time of releasing the push on the input shaft, and improve the operability of the brake. An input shaft (1) is located in a valve body (41).
A plunger 41 is disposed between the reaction disk 3 and the reaction disk 25 on the output shaft 22 side. And this plunger 4
4, a movable valve seat 45 for operating the poppet valve element 14,
A reaction piston 46 for receiving a reaction force from the reaction disk 25, a stepped sleeve 49 slidably fitted around the base end side outer periphery of the reaction force piston 46, and a reaction piston 4
6, an inner spring 50 which is disposed between the stepped sleeve 49 and the movable valve seat 45 and is always in a free length state;
An outer spring 51 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic booster which is preferably used for boosting, for example, a depression force on a brake pedal of a vehicle and transmitting the boosted force to a master cylinder.

[0002]

2. Description of the Related Art Generally, a brake system of a vehicle is provided with a pneumatic booster as a booster device between a brake pedal and a master cylinder.

A conventional pneumatic booster of this type will be described with reference to FIGS. 7 to 11 by taking a tandem-type pneumatic booster as an example.

In FIG. 1, reference numeral 1 denotes a casing of a pneumatic booster. The casing 1 comprises a front shell 2, a rear shell 3 and an intermediate shell 4, which are fixed to each other on the outer peripheral side in an airtight state. In the front shell 2, a stepped recess 2B for accommodating a part of a master cylinder (not shown) is formed at the center of the front wall 2A.

A vehicle (not shown) is mounted on the rear shell 3.
A rear cylindrical portion 3B protrudes axially outward from a rear wall 3A serving as an attachment surface to the rear wall 3B. On the other hand, a hole 4A for inserting a valve body 7 to be described later is formed in the middle shell 4 at the center thereof.

[0006] Reference numerals 5 and 6 denote power pistons formed of a diaphragm and the like provided in the casing 1. The power piston 5 is fixed on the outer peripheral side between the front shell 2 and the intermediate shell 4, and is connected to the front shell 2 and the intermediate shell 4. Are defined as a first negative pressure chamber (constant pressure chamber) A and a first variable pressure chamber B. The outer periphery of the power piston 6 is fixed between the front shell 2 and the rear shell 3 via the intermediate shell 4.
Are defined as a second negative pressure chamber (constant pressure chamber) C and a second variable pressure chamber D.

Reference numeral 7 denotes a valve body which is inserted through the rear cylindrical portion 3B of the rear shell 3 and the hole 4A of the intermediate shell 4 so as to be axially displaceable in the casing 1. The valve body 7 has a large diameter portion 7A side. The small-diameter cylindrical portion 7 </ b> B extends from the rear cylindrical portion 3 </ b> B of the rear shell 3 to the outside of the casing 1. And, the valve body 7 has the power piston 5,
6, the casing 1 is displaced in the axial direction in conjunction with the displacement. Also, the large diameter portion 7A of the valve body 7
Are formed with communication passages 8 and 9 apart from each other.
Is to constantly communicate between the transformer chambers B and D.

On the other hand, the communication passage 8 always communicates between the negative pressure chambers A and C, and also extends in the axial direction toward the small-diameter cylindrical portion 7B, and together with the later described poppet valve body 14 and the like, the variable pressure chamber B , D to and from the negative pressure chambers A and C. For this purpose, an annular valve seat 7C is formed in the small diameter cylindrical portion 7B of the valve body 7 at the opening end side of the communication passage 8 as shown in FIG. The valve element 14 is configured to be separated and seated. The valve body 7 is integrally formed with a cylindrical projecting portion 7D which is located on the inner peripheral side of the large diameter portion 7A and protrudes in the axial direction toward the output shaft 22 described later.

Further, a stepped hole 10 is formed in the valve body 7 as a through hole extending in the axial direction from the position of the valve seat 7C toward the cylindrical projecting portion 7D. Plunger 19 is slidably inserted. The valve body 7 has a key insertion hole 11 located on the base end side of the small-diameter cylindrical portion 7B and extending in the radial direction and another communication passage 12, and a stop key 2 described later is formed in the key insertion hole 11.
0 is inserted. The communication passage 12 is provided with the stepped hole 10.
The inside of the large-diameter portion is always in communication with the transformation chamber D, and is also constantly communicated with the transformation chamber B via the communication passage 9.

Reference numeral 13 denotes one end of the rear cylindrical portion 3 of the rear shell 3.
B, and the other end is an input shaft provided to be inserted into the small-diameter cylindrical portion 7B of the valve body 7, and the input shaft 13
The protruding end is connected to a brake pedal (not shown) of the vehicle, and is pushed in the direction of arrow E1 in FIG. 7 when the brake is operated. As shown in FIG. 8, a spherical portion 13A is integrally formed on the tip (the other end) side of the input shaft 13, and the spherical portion 13A is connected to a plunger 19 described later by means such as caulking.

Reference numeral 14 denotes a poppet valve element provided in the small-diameter cylindrical portion 7B of the valve body 7. The poppet valve element 14 is formed in a substantially cylindrical shape by using an elastic material. It is fixed to the inner peripheral wall of the small-diameter cylindrical portion 7B through the intermediate portion. The other end of the poppet valve element 14 is connected to the weak spring 1.
5, the valve seat 7 of the valve body 7 as shown in FIG.
The poppet valve element 14 is always urged toward C, and the poppet valve element 14 is configured to be separated and seated on a contact portion 19A of a plunger 19 and a valve seat 7C of the valve body 7 described later.

A return spring 16 is disposed between the small-diameter cylindrical portion 7B of the valve body 7 and the input shaft 13.
6 always biases the input shaft 13 toward the valve body 7 in the direction of arrow E2 in FIG. 7, and when the pushing operation is released, the valve body 7 moves the inside of the casing 1 into the initial position shown in FIG. The input shaft 13 with respect to the valve body 7 until it returns to the position regulated by the stop key 20 of FIG.
Press in the direction. Thus, when the operation on the input shaft 13 is released, the return spring 16 separates the poppet valve element 14 from the valve seat 7C of the valve body 7 as shown in FIG.

A filter 17 is mounted in the small-diameter cylindrical portion 7B of the valve body 7 as shown in FIG.
Is for cleaning air as an external working gas introduced into the small-diameter cylindrical portion 7B from the outside of the casing 1 to prevent dust and the like from entering the casing 1.

Reference numeral 18 denotes a boot for protecting the protruding end side of the small-diameter cylindrical portion 7B. The boot 18 is formed as a bellows-like cylindrical body made of an elastic material, and one end thereof is provided on the small-diameter cylindrical portion 7B.
Is fixed to the front end side of the. The other end of the boot 18 is attached to the front end of the rear cylinder 3B of the rear shell 3, and the outer peripheral surface of the small-diameter cylinder 7B of the valve body 7 that slides inside the rear cylinder 3B of the rear shell 3 as shown in FIG. Is protected from dust and the like.

A plunger 19 is slidably inserted into the stepped hole 10 of the valve body 7. One end of the plunger 19 is formed in a stepped cylindrical shape, and projects into the small-diameter cylindrical portion 7B. I have. The input shaft 13 is fixed to the projecting end side of the plunger 19, and the plunger 19 is configured to be displaced integrally with the input shaft 13 in the directions indicated by arrows E1 and E2 in FIG.

As shown in FIG. 8, an abutting portion 19A as an annular valve seat having a smaller diameter than the valve seat 7C of the valve body 7 is integrally provided on the protruding end side of the plunger 19, as shown in FIG. The corresponding contact portion 19A introduces and shuts off the atmospheric pressure in the small-diameter cylindrical portion 7B to the communication passage 12 side by detaching and seating on the poppet valve body 14. And plunger 19
Abutment portion 19A constitutes a valve mechanism together with valve seat portion 7C of valve body 7 and poppet valve body 14, and controls communication and shutoff of variable pressure chambers B and D with respect to atmospheric pressure in small-diameter cylindrical portion 7B, The communication between the pressure chambers A and C and the communication between the variable pressure chambers B and D and the interruption thereof are controlled as described later.

As shown in FIG. 8, the other end of the plunger 19 has the pressure-receiving convex portion 1 inserted into the small-diameter portion of the stepped hole 10.
9B, a gap S having a predetermined fixed size is formed between the distal end surface of the pressure receiving convex portion 19B and a reaction disk 25 described later. Further, an annular groove 19 is provided on the outer peripheral side of the plunger 19 at a position corresponding to the key insertion hole 11.
C is formed, and a stop key 20 is attached to the annular groove 19C in an engaged state.

Reference numeral 20 denotes a stop key for regulating the return position of the plunger 19. The stop key 20 is formed as a substantially rectangular flat plate.
And is loosely engaged with the annular groove 19C of the plunger 19 through the opening. The end of the stop key 20 protrudes from the valve body 7 by a certain dimension in the radial direction, and comes into contact with the stopper member 21 on the rear shell 3 side, whereby the valve body 7 and the plunger 19 at the time of releasing the pushing operation on the input shaft 13 are released. Is restricted as shown in FIG.

Reference numeral 22 denotes an output shaft for outputting to the outside in a state where the pushing operation force of the input shaft 13 is boosted. The output shaft 22 is provided with a large-diameter flange portion 22A on one end side. Reference numeral 22A is fitted through the reaction disk 25 to the cylindrical projection 7D of the valve body 7. And
At the time of pushing operation on the input shaft 13, the output shaft 22 is pushed with a large output (see FIG. 9) in the direction of arrow F1 in FIG. The other end of the output shaft 22 projects outside through the stepped recess 2B of the front shell 2 and the like, and presses the piston (not shown) of the master cylinder in the axial direction.

Reference numeral 23 denotes a spring receiver provided on the side of the cylindrical projection 7D of the valve body 7. The spring receiver 23 is mounted on the outer peripheral side of the cylindrical projection 7D via the flange 22A of the output shaft 22, and is returned. The structure is such that the flange portion 22A is prevented from coming off together with the spring 24. The return spring 24 is disposed between the spring support 23 and the stepped recess 2B of the front shell 2, and constantly biases the valve body 7 in the direction of arrow F2 in FIG.

Reference numeral 25 denotes a reaction disk as a reaction member disposed between the cylindrical projection 7D of the valve body 7 and the flange 22A of the output shaft 22. The reaction disk 25 is a disk made of an elastic resin material. The thrust generated in the valve body 7 in the direction of arrow F1 in FIG. 7 due to the pressure difference between the negative pressure chambers A and C and the variable pressure chambers B and D is transmitted to the output shaft 22 as described later.

At this time, the reaction disk 25 is elastically deformed as shown in FIG. Just swell. In this state, the reaction disk 25 receives the reaction force from the output shaft 22 via the flange portion 22A and transmits a part of the reaction force to the input shaft 13 via the pressure receiving convex portion 19B, and the brake pedal This is to generate a response on the side.

Numeral 26 denotes a negative pressure introducing pipe provided in the front shell 2. The negative pressure introducing pipe 26 is made of, for example, an L-shaped pipe or the like as shown in FIG. They are connected via a stop valve (neither is shown) or the like. The negative pressure introducing pipe 26 guides the negative pressure generated in the intake manifold during the operation of the engine into the negative pressure chambers A and C, thereby forming these negative pressure chambers A and C.
The inside is maintained at a pressure lower than the atmospheric pressure.

Reference numeral 27 denotes a fixing bolt for fixing the master cylinder to the front shell 2;
Reference numerals 8, ... denote mounting bolts fixed to the rear wall 3A of the rear shell 3, and the mounting bolts 28 are used to mount the entire casing 1 including the rear shell 3 to the inner wall of the engine room of the vehicle.

In the pneumatic booster according to the prior art having the above-described structure, when the driver of the vehicle depresses the brake pedal, the input shaft 13 is moved in the direction indicated by arrow E1.
The plunger 19 is also displaced integrally with the input shaft 13 in the gap S shown in FIG. When the displacement of the plunger 19 causes the annular contact portion 19A to separate from the poppet valve body 14 whose follow-up is restricted by the contact with the valve seat portion 7C of the valve body 7, the small-diameter cylindrical portion 7B of the valve body 7 Atmospheric pressure is introduced into the transformation chambers B and D from inside through the communication paths 12 and 9, and a pressure difference is generated between the negative pressure chambers A and C and the transformation chambers B and D.

That is, as shown by a characteristic line 30 in FIG. 9, when the input (pressing operation force) to the input shaft 13 reaches the input value fa, the contact portion 19A of the plunger 19 is moved to the poppet valve body 14.
The valve body 7 moves forward due to the pressure difference between the negative pressure chambers A and C and the variable pressure chambers B and D, and the thrust at this time is transmitted to the output shaft 22 via the reaction disk 25. Is transmitted, so-called jump-in occurs and the output shaft 2
The output from 2 rises sharply to the output value Fa. After that, as the input to the input shaft 13 (the pedal effort) increases, the output also increases at a constant boost ratio.

When the pedaling force on the input shaft 13 exceeds the input value fa, the valve body 7 moves the power piston 5 according to the pressure difference between the negative pressure chambers A and C and the variable pressure chambers B and D. 6
At the same time, the poppet valve element 14 is displaced in the same direction as the valve body 7 while seated on the valve seat portion 7C. During this time, the contact portion 1 of the plunger 19
9A repeats the detachment / seating of the poppet valve element 14.

When the pedaling force on the input shaft 13 is held at an arbitrary value, the input in the direction indicated by the arrow E1 to the input shaft 13 and the reaction in the direction indicated by the arrow F2 through the reaction disk 25 are applied to the input shaft 13 as shown in FIG. By maintaining a balanced state with the force, the contact portion 19A of the plunger 19 is seated on the poppet valve element 14.

Further, when the pedal (input shaft 13) is greatly depressed to increase the input to the maximum load point input value fb shown in FIG. 9, the negative pressure chambers A, C and the variable pressure chambers B, D
And the pressure difference between them becomes maximum, and the boosting action due to the pressure difference cannot be exerted even if the input shaft 13 is further depressed. The output shaft 22 is displaced in the axial direction substantially integrally with the input shaft 13 in a region where the output value is equal to or larger than the output value Fb, and when the flange portion 22A comes into contact with the stepped recess 2B of the front shell 2, the stroke end is reached. Reach

On the other hand, when the brake operation is released,
The input shaft 13 is pushed back in the direction of arrow E2 by the return spring 16, and the plunger 19 is accordingly pulled in the same direction. For this reason, the contact portion 19A of the plunger 19 is
As shown in FIG.
To the atmosphere. At this time, the plunger 19 is connected to the poppet valve 1 via the contact portion 19A.
4 is pressed against the weak spring 15 in the direction of the arrow E2 to forcibly separate the poppet valve 14 from the valve seat 7C of the valve body 7.

As a result, the negative pressure chambers A and C and the variable pressure chambers B and D communicate with each other through the communication passages 8 and 12, and the negative pressure in the negative pressure chambers A and C is reduced. , D side, the pressure difference between the negative pressure chambers A, C and the variable pressure chambers B, D becomes lower than the pressure difference before the brake operation is released. And
The output shaft 22 is pushed back together with the valve body 7 in the direction indicated by the arrow F2 by the return spring 24.
8 comes into contact with the stopper member 21 as shown in FIG.

Then, with the stop key 20 in contact with the stopper member 21, the final return position of the plunger 19 is regulated, and the power pistons 5, 6, the valve body 7,
The input shaft 13 and the output shaft 22 return to the initial positions shown in FIG. At this time, the poppet valve element 14 is brought into contact with the valve seat 7C of the valve body 7 and the contact portion 19A of the plunger 19.
And prepares for the next brake operation while maintaining the variable pressure chambers B and D in the same negative pressure state as the negative pressure chambers A and C.

[0033]

By the way, in the above-mentioned prior art, the output which is boosted with respect to the pedaling force (input) to the input shaft 13 along the characteristic line 30 in FIG. Can be taken from. However, when the brake operation is released, the output with respect to the input becomes a larger value than in the case of the brake operation, and the output decreases with respect to the input as shown by a characteristic line 31 in FIG.

For this reason, the input / output characteristics between the input shaft 13 and the output shaft 22 include a brake operation (when the pedal is depressed and held) and a release (when the pedal is returned).
, A hysteresis occurs in which the magnitude of the output becomes larger when the brake is released for the same magnitude of the input, and a problem such as a delay in releasing the brake occurs.

That is, the hysteresis characteristic is caused by the behavior of the reaction disk 25 as shown in FIGS. In the equilibrium state of the brake operation shown in FIG. It bulges into the perforated hole 10 by the dimension S1, and a part of the reaction force is transmitted to the input shaft 13 via the pressure receiving convex portion 19B.

However, when the brake operation is released from this equilibrium state, the plunger 19 is pushed back in the direction of arrow E2 by the return spring 16 integrally with the input shaft 13, and the plunger 19 is moved to the valve body as shown in FIG. Then, the poppet valve element 14 is separated from the valve seat 7C. And
During this time, the reaction disk 25 continues to receive the return force in the direction indicated by the arrow F2 from the output shaft 22 side.
As shown in the figure, the bulging amount of the reaction disk 25 increases to the dimension S2 (S2> S1) with respect to the above-mentioned equilibrium state.

Therefore, the input / output characteristics have hysteresis between the time of the brake operation and the time of the release of the brake operation, as indicated by characteristic lines 30 and 31 in FIG. There is a possibility that brake release delay is likely to occur and brake feeling deteriorates.

The present invention has been made in view of the above-described problems of the prior art, and the present invention can suppress the occurrence of hysteresis in the input / output characteristics, and can improve the responsiveness at the time of releasing the push on the input shaft. For example, it is an object of the present invention to provide a pneumatic booster capable of performing a brake releasing operation early and improving a brake feeling.

Another object of the present invention is to enable the boost ratio of the output to the input to be switched in a plurality of stages, so that, for example, a sufficiently large braking force can be generated as an output even during an emergency braking operation, It is an object of the present invention to provide a pneumatic booster capable of suppressing hysteresis which is likely to occur in characteristics to be small.

[0040]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a casing, a power piston fixed to an outer peripheral side of the casing, and defining a constant pressure chamber and a variable pressure chamber in the casing. A valve body fixed to the inner peripheral side of the power piston and capable of being displaced in the axial direction in conjunction with the displacement of the power piston in the casing; one end protruding outside one side of the casing; An input shaft having a side inserted into the valve body;
Communication and disconnection of the variable pressure chamber with the external working gas and communication and disconnection of the variable pressure chamber with the constant pressure chamber are provided in the valve body for cooperating with a poppet valve element provided in the valve body. A plunger displaced relative to the valve body by a pushing operation of the input shaft, an output shaft having one end fitted to the valve body and the other end protruding outside from the other side of the casing; Interposed between one end of the output shaft and the valve body,
A thrust generated in the valve body due to a pressure difference between the variable pressure chamber and the constant pressure chamber during a pushing operation of the input shaft is transmitted to the output shaft, and a part of a reaction force from the output shaft is transmitted to the plunger. Applied to a pneumatic booster consisting of a reaction member for transmitting to a pressure booster.

The plunger is characterized in that the other end of the input shaft is integrally attached to the plunger, and the input shaft side member for operating the poppet valve element and the input shaft member. A first output shaft-side member that is provided so as to be relatively displaceable with respect to the shaft-side member, the reaction member abuts when a reaction force from the output shaft is transmitted to the reaction member when the input shaft is pressed; The first output shaft side member is provided so as to be relatively displaceable with respect to the input shaft side member and the first output shaft side member, and the reaction force from the output shaft is reduced when the input shaft is pushed. When transmitted to the member, the reaction member abuts, and a second output shaft side member provided with a locking portion for the valve body on the outer peripheral side, the first output shaft side member and the input shaft side. Between components When the reaction force from the output shaft is not transmitted to the reaction member when the input shaft is not pushed, a free length state is interposed between the first output shaft side member and the input shaft side member. Disposed between the first spring member and the second output shaft side member and the input shaft side member. When the input shaft is not pushed, a reaction force from the output shaft is applied to the reaction member. When not transmitted, the second output shaft side member and the second spring member interposed in a free length state between the second output shaft side member and the input shaft side member. When the reaction force from the output shaft is transmitted to the reaction member by the pushing, and the first output shaft side member is relatively displaced with respect to the input shaft side member, the second output shaft Abutting against a locking portion of the side member, the second output shaft Member is in the provision of the stepped portion for restraining the relative displacement relative to the valve body.

With this configuration, for example, when the input shaft is pushed to perform a brake operation, the input shaft side member is displaced integrally with the input shaft to operate the poppet valve body, and the variable pressure chamber and the constant pressure chamber are operated. And a pressure difference is generated. Then, the valve body is pushed toward the output shaft by the pressure difference, and generates an output having the first boosting ratio on the output shaft.
At this time, the reaction force from the output shaft is transmitted to the first and second output shaft side members through the reaction member, so that the first and second output shaft side members are relatively displaced toward the input shaft side member. Then, the first and second spring members are elastically deformed by a flexure amount corresponding to the reaction force, and the reaction force is transmitted to the input shaft via the input shaft side member and the like.

Further, in this state, the pushing operation force on the input shaft is increased, and the reaction force from the output shaft is correspondingly increased, so that the locking portion provided on the second output shaft side member is reduced. When the second output shaft-side member is in contact with the step portion of the valve body, the relative displacement of the second output shaft-side member with respect to the valve body is restricted, so that the reaction force from the output shaft is reduced by the first output shaft-side member and the first spring. The input shaft is transmitted to the input shaft through the member and the input shaft side member.
Input / output characteristics having a second boosting ratio larger than the boosting ratio of.

On the other hand, when the pushing on the input shaft is released to release the brake operation, the input shaft side member is returned together with the input shaft in the opposite direction to that during the brake operation, and the poppet valve body is moved relative to the valve body. By relative displacement of
The variable pressure chamber is communicated with the constant pressure chamber to gradually reduce the pressure difference between the two. Then, the output gradually decreases in response to the decrease in the input.
The second spring member is in an elastically deformed state, and keeps pressing the first and second output shaft side members toward the reaction member.

Thus, the first and second spring members can urge the first and second output shaft side members toward the reaction member until the first and second spring members return to the free length state. It is possible to suppress relative displacement so as to retreat toward the input shaft side member together with the output shaft side member, and prevent the input / output characteristics from being different between the time of the brake operation and the time of the release of the brake operation.

[0046]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A pneumatic booster according to an embodiment of the present invention will be described below in detail with reference to FIGS. In the embodiment, the same components as those of the above-described conventional technology are denoted by the same reference numerals, and description thereof will be omitted.

FIGS. 1 to 5 show a first embodiment of the present invention. In the figure, reference numeral 41 denotes a valve body employed in the present embodiment, and the valve body 41 has a large diameter portion 41A, substantially similar to the valve body 7 described in the related art.
The small-diameter cylindrical portion 41B, the valve seat portion 41C, the cylindrical projecting portion 41D and the like are formed, and the communication passages 8, 9, 12 and the key insertion hole 11 are formed.

However, in the valve body 41, a stepped hole 42 formed in the axial direction from the valve seat 41C toward the cylindrical projection 41D has a different shape. As shown in FIG. 2, a collar 43 serving as a bearing cylinder for a stepped sleeve 49 described later is detachably fitted to the inner peripheral side of the cylindrical projecting portion 41D. An annular step portion 41E is formed in the valve body 41 at a position deeper than the stepped hole 42 than the collar 43, and a stepped sleeve 49 is provided between the stepped portion 41E and the collar 43. 42, it is disposed so as to be relatively displaceable in the axial direction.

Reference numeral 44 denotes a plunger provided in the stepped hole 42 of the valve body 41. The plunger 44 is different from the plunger 19 described in the prior art, as shown in FIG. It comprises a force piston 46, a stepped sleeve 49, an inner spring 50, an outer spring 49 and the like.

A movable valve seat 45 is slidably inserted into the stepped hole 42 of the valve body 41 and constitutes a part of the plunger 44 as an input shaft side member.
Has a stepped cylindrical shape on one end side, and projects into the small-diameter cylindrical portion 41B of the valve body 41. And movable valve seat 4
5, the spherical portion 13A of the input shaft 13 is fixed to the input shaft 1 by means of caulking or the like.
3, and is displaced in the directions indicated by arrows E1 and E2 in FIG.

Here, the projecting end side of the movable valve seat 45 is shown in FIG.
As shown in FIG. 5, a contact portion 45A as an annular valve seat formed to have a smaller diameter than the valve seat portion 41C of the valve body 41 is provided integrally, and the contact portion 45A is detached and seated on the poppet valve body 14. At this time, the atmospheric pressure in the small-diameter cylindrical portion 41B is introduced into the communication passage 12 or cut off.

The contact part 45A of the movable valve seat 45 is
Valve seat 41C of valve body 41 and poppet valve element 14
And a valve mechanism for controlling the communication and shutoff of the variable pressure chambers B and D with respect to the atmospheric pressure in the small-diameter cylindrical portion 41B, and the communication and shutoff of the variable pressure chambers B and D with the negative pressure chambers A and C as described later. Control.

A cylindrical projection 45B is integrally formed on the other end of the movable valve seat 45, and a circular recess 45C is formed on the inner periphery thereof.
It has become. As shown in FIG. 2, a shaft portion 4 of a reaction force piston 46, which will be described later,
The leading end of 6B is inserted with a gap S11. Further, an annular groove 45D is formed at a position corresponding to the key insertion hole 11 on the outer peripheral side of the intermediate portion of the movable valve seat 45.
A stop key 20 is attached to D in the engaged state as in the prior art.

A reaction force 46 is inserted into the stepped hole 42 of the valve body 41 via a stepped sleeve 49 or the like, and is a first output shaft side member which is relatively displaceable with respect to the movable valve seat 45. Shows the piston. The base end of the reaction piston 46 is slidably inserted into the inner peripheral side of the stepped sleeve 49, and an annular flange 46A is integrally formed on the outer peripheral side thereof. The proximal end surface of the reaction force piston 46 faces the reaction disk 25 in the axial direction. When the brake operation is completely released, a gap S having a predetermined size is formed between the reaction piston 46 and the reaction disk 25. It is formed as shown in FIG.

On the other hand, when the brake is operated, the reaction disk 25 is elastically deformed by the reaction force from the output shaft 22 as shown in the prior art, as shown in FIG.
The reaction force piston 46 has a reaction disk 25 at the base end.
Abut. The reaction force piston 46 transmits the reaction force at this time to the movable valve seat 45 via the inner spring 50 and the like.

The reaction force piston 46 is integrally formed with a shaft portion 46B extending axially in the stepped hole 42 of the valve body 41 toward the concave portion 45C of the movable valve seat 45, and the tip of the shaft portion 46B is formed. The side is inserted into the recess 45C. The tip of the shaft portion 46B of the reaction force piston 46 is
Is strongly pushed to the maximum load point input fb1 or more, which will be described later, is pushed into the concave portion 45C of the movable valve seat 45 by the reaction force from the reaction disk 25 to a position where it comes into contact with the bottom surface. Reference numeral 46 designates the maximum amount of deflection of the springs 50 and 51 between the movable valve seat 45 and the cylindrical projection 45B.

Reference numeral 47 denotes a retaining ring as a retaining member which is detachably attached to the distal end of the shaft portion 46B of the reaction force piston 46, and reference numeral 48 is retained by the retaining ring 47 on the outer periphery of the distal end side of the shaft portion 46B. The spring receiver 48 is formed of an annular plate or the like, and the tip of the shaft portion 46B of the reaction force piston 46 is slidably fitted on the inner peripheral side thereof. The spring receiver 48 is provided on the cylindrical projection 45 of the movable valve seat 45.
B is disposed between B and the springs 50 and 51, and transmits a spring force when the springs 50 and 51 are flexed and deformed to the movable valve seat 45 as a reaction force from the output shaft 22.

Reference numeral 49 denotes a stepped sleeve as a second output shaft side member which is located on the base end side outer periphery of the reaction force piston 46 and is inserted into the stepped hole 42 of the valve body 41 so as to be relatively displaceable. The stepped sleeve 49 is formed as a short tubular body that is externally mounted on the base end side of the reaction force piston 46 and is slidably fitted on the inner peripheral side of the collar 43. An annular flange portion 49A projecting radially outward is integrally formed on the outer peripheral side of the stepped sleeve 49, and the flange portion 49A is formed integrally therewith.
Constitutes a locking portion that comes into contact with the step portion 41E of the valve body 41.

Here, the flange portion 4 of the stepped sleeve 49
9A is separated from the stepped portion 41E of the valve body 41 with a clearance C1 as shown in FIG. 2 until the middle of the braking operation, and the operating force on the input shaft 13 side is changed to the input value f shown in FIG.
When the clearance reaches c1, the clearance C1 becomes zero (C1 = 0), and the flange portion 49A is connected to the step portion 4 of the valve body 41.
By contacting 1E, the relative displacement of the stepped sleeve 49 with respect to the valve body 41 is regulated.

On the inner peripheral side of the stepped sleeve 49, there is formed an annular stepped portion 49B for preventing the reaction force piston 46 from coming off, and the stepped portion 49B and the flange 46A of the reaction force piston 46 are always in contact with each other. 2, a clearance C2 is secured as shown in FIG. The stepped sleeve 49 is formed so that the clearance C2 on the inner peripheral side is larger than the clearance C1 on the outer peripheral side. Even when the clearance C1 becomes zero at the input value fc1 shown in FIG.
Does not become zero (C2> 0).

Reference numeral 50 denotes an inner spring serving as a first spring member disposed in the stepped hole 42 of the valve body 41 and disposed between the reaction force piston 46 and the spring receiver 48.
The inner spring 50 is a shaft portion 46B of the reaction force piston 46.
A coil spring or the like is inserted around the periphery, and as shown in FIG. 2, the reaction force piston 46 receives the reaction force from the output shaft 22 (a gap S is formed between the reaction disk 25 and the reaction force piston 46). ) Is disposed between the reaction force piston 46 and the spring receiver 48 in a free length state.

That is, in a state where the movable valve seat 45 and the like have returned to the initial positions shown in FIGS. 1 and 2 before the brake operation is performed, an inner spring is provided between the reaction force piston 46 and the spring receiver 48. 50 is interposed (interposed) in a free length state. At this time, the inner spring 50 does not apply a spring force to either the movable valve seat 45 or the reaction force piston 46. Then, the input shaft 13 is pushed in the direction of arrow E1 from the initial state operation state shown in FIGS. 1 and 2 by the brake operation, and at the stage when the so-called equilibrium state after jump-in is reached, as shown in FIG. The reaction disk 25 is elastically deformed by the reaction force from the output shaft 22, and a part of the reaction force is transmitted to the reaction force piston 46.

For this reason, the inner spring 50 causes the spring receiver 4 on the movable valve seat 45 side by the reaction force from the reaction force piston 46 side.
8, the movable valve seat 45 and the reaction force piston 46 are urged in opposite directions with a spring force corresponding to the reaction force, and the equilibrium state after the jump-in is maintained. The inner spring 50 is configured to be gradually compressed and deformed as the reaction force from the reaction force piston 46 increases, and to be compressed and deformed until the tip of the shaft portion 46B comes into contact with the concave portion 45C of the movable valve seat 45. I have.

When the brake operation is released,
Until the movable valve seat 45 and the like return to the initial position (while the reaction force from the output shaft 22 is being transmitted to the reaction disk 25), the inner spring 50 continues to bend and deform as shown in FIG. As a result, the inner spring 50 continues to urge the reaction force piston 46 in the direction of arrow F1 in FIG. 4, and the amount of swelling of the reaction disk 25 toward the end face of the reaction force piston 46 is substantially constant. (The dimension Sa shown in FIG. 4) to prevent the hysteresis described later.

An outer spring 51 is located in the stepped hole 42 of the valve body 41 and disposed between the flange 49A of the stepped sleeve 49 and the spring receiver 48 as a second spring member. Although the outer spring 51 is formed of a coil spring or the like similarly to the inner spring 50, the outer spring 51 has a coil diameter larger than that of the inner spring 50, and the entire length in the free length state is formed to be longer by a certain dimension. . And the outer spring 51
Until the stepped sleeve 49 receives the reaction force from the output shaft 22 as shown in FIG.
And is arranged in a free length state between them.

That is, in a state where the movable valve seat 45 and the like have returned to the initial positions shown in FIGS. 1 and 2 before the brake operation is performed, the outer spring is placed between the stepped sleeve 49 and the spring receiver 48. 51 is interposed (interposed) in a free length state, and does not apply a spring force to either the movable valve seat 45 or the stepped sleeve 49. When the input shaft 13 is pushed by the brake operation in the direction indicated by the arrow E1 from the initial operation state shown in FIGS. 1 and 2) and reaches a so-called equilibrium state after jump-in, as shown in FIG. The reaction disk 25 is elastically deformed by the reaction force from the output shaft 22, and a part of the reaction force is transmitted to the stepped sleeve 49.

For this reason, the outer spring 51 causes the spring receiver 4 on the movable valve seat 45 side by the reaction force from the stepped sleeve 49 side.
8, the movable valve seat 45 and the stepped sleeve 49 are urged in opposite directions with a spring force corresponding to the reaction force. Then, the outer spring 51 is gradually compressed and deformed as the reaction force from the stepped sleeve 49 increases,
For example, the configuration is such that the flange portion 49A of the stepped sleeve 49 is compressed and deformed until it comes into contact with the step portion 41E of the valve body 41.

When the brake operation is released,
Like the inner spring 50, the outer spring 51 continues to bend and deform as shown in FIG. 4 until the movable valve seat 45 and the like return to the initial position. Thereby, the outer spring 51
Will continue to urge the stepped sleeve 49 in the direction indicated by the arrow F1 in FIG. 4, so that the amount of bulging of the reaction disk 25 toward the end face side of the stepped sleeve 49 is substantially constant (dimensions). Sb), and performs a hysteresis preventing action described later.

Further, the outer spring 51 and the inner spring 50 are configured such that the stepped sleeve 49 is prevented from being removed from the flange 46A of the reaction force piston 46 by the stepped portion 49B, and the spring receiver 48 is fixed by the retaining ring 47 to the reaction force piston. 46 shaft part 4
6B, the spring support 48 and the stepped sleeve 49
And a sub-assembly, and is handled as a single unit during the assembling work as described later.

The pneumatic booster according to the present embodiment has the above-described configuration, and its basic operation is not particularly different from that of the prior art.

According to the present embodiment, however, the plunger 44 located in the stepped hole 42 of the valve body 41 and disposed between the input shaft 13 and the reaction disk 25 on the output shaft 22 side receives the input. A movable valve seat 45 fixed to the spherical portion 13A of the shaft 13 to actuate the poppet valve element 14 by being detached from and seated on the poppet valve element 14, and a relative displacement between the movable valve seat 45 and the reaction disk 25 is possible. A reaction force piston 46 disposed to receive a reaction force from the reaction disk 25, and a reaction force piston 46 slidably inserted between the base end outer periphery of the reaction force piston 46 and the collar 43. A stepped sleeve 49 for receiving the force,
A reaction force piston 46, an inner spring 50 and an outer spring 51 which are disposed between the stepped sleeve 49 and the movable valve seat 45 via a spring receiver 48 and are always in a free length state are constituted as follows. The following operational effects can be obtained.

That is, when the driver of the vehicle depresses the brake pedal, the input shaft 13 is pushed together with the movable valve seat 45 in the direction indicated by the arrow E1, whereby the movable valve seat 45 is moved.
The contact portion 45A opens the poppet valve body 14, and the atmospheric pressure is introduced into the variable pressure chambers B and D. As a result, a pressure difference is generated between the negative pressure chambers A and C and the variable pressure chambers B and D, and the output shaft 22 generates an output in the direction of arrow F1 via the power pistons 5, 6 and the valve body 41. .

At this time, the reaction disk 2
5 is elastically deformed by the reaction force from the output shaft 22, the reaction disk 25 is brought into contact with the reaction force piston 46 and the proximal end face of the stepped sleeve 49 until the collar 43 is in contact with the reaction force piston 46 and the stepped sleeve 49.
The bulges into the (stepped holes 42) by the dimensions Sa and Sb in FIG.

As a result, the inner spring 50 is transmitted between the reaction force piston 46 and the movable valve seat 45 from the output shaft 22 (reaction disk 25) to the reaction force piston 46 with the pressure receiving area Ap shown in FIG. It is elastically deformed and deformed by the reaction force, and the reaction force piston 46 is pressed toward the reaction disk 25 by a spring force corresponding to the reaction force.

The outer spring 51 is elastically bent and deformed by the reaction force transmitted from the reaction disk 25 to the stepped sleeve 49 with the pressure receiving area (As-Ap) in FIG. The disk 25 is pressed by the spring force corresponding to the reaction force.

At this time, as indicated by a characteristic line 52 shown in FIG.
When the input (pressing operation force) to the input shaft 13 reaches the input value fa1, so-called jump-in is dynamically generated, so that the output from the output shaft 22 rapidly rises to the output value Fa1. Then, as the input to the input shaft 13 (pedal force) increases, the output also increases at the first boosting ratio KA as shown by the characteristic line portion 52A.

In this case, the first boost ratio KA of the output to the input is determined by the
5 and the pressure receiving area Ap of the reaction force piston 46.
And the pressure receiving area (As-Ap) of the stepped sleeve 49,

[0078]

KA = Ao / Ap + (As-Ap) = Ao / As

The reaction force piston 46 and the stepped sleeve 4
9 is provided between the reaction disc 25 and the movable valve seat 45 via the inner spring 50 and the outer spring 51 so as to be relatively displaceable, so that the swelling amount of the reaction disc 25 is defined as a dimension Sa. For example, FIG.
The bulge amount (Sa> S1) can be set to be larger than the bulge amount S1 described in the prior art shown in FIG. 9, and the output value Fa1 at the time of jump-in can be set to the output of the prior art illustrated in FIG. The boost ratio KA itself can be set to be large as well as being increased as compared with the value Fa.

Next, when the depressing operation force of the input shaft 13 is further increased and the input is increased to the input value fc1 shown in FIG. 5, the flange 49A of the stepped sleeve 49 comes into contact with the step 41E of the valve body 41. 3, the clearance C 1 shown in FIG. 3 becomes zero (C 1 = 0), and the relative displacement of the stepped sleeve 49 with respect to the valve body 41 is restricted. Also at this time, the clearance C2 between the flange 46A of the reaction force piston 46 and the step 49B of the stepped sleeve 49 is maintained.
Does not become zero as shown in FIG. 3 (C2> 0),
A gap S12 (S11>S12> 0) is also provided between the tip of the shaft portion 46B of the reaction force piston 46 and the concave portion 45C of the movable valve seat 45.

At this stage, the relative displacement of the stepped sleeve 49 with respect to the valve body 41 is regulated, and only the reaction force piston 46 can be relatively displaced with respect to the valve body 41. The force is transmitted by the reaction force piston 46 with the pressure receiving area Ap in FIG. 3, and the reaction force causes the inner spring 50 to be elastically deformed and deformed, and the force corresponding to the reaction force is applied to the movable valve seat 45 side. Will be conveyed.

For this reason, as indicated by a characteristic line 52 shown in FIG.
At the stage when the input to the input shaft 13 (push operation force) reaches the input value fc1, the output from the output shaft 22 responds to the second boost ratio KB (KB> KA) in response to the increase in the input. Line part 52B
Along with the output value Fc1. In this case, the second boost ratio KB of the output with respect to the input is represented by the output shaft 2
2 from the pressure receiving area Ao of the reaction disk 25 and the pressure receiving area Ap of the reaction force piston 46

[0083]

## EQU2 ## It is obtained as a pressure receiving area ratio of KA = Ao / Ap.

When the input shaft 13 is further depressed, the clearance C2 between the flange 46A of the reaction force piston 46 and the step 49B of the stepped sleeve 49 becomes zero (C2 = 0), and the reaction force The gap S12 between the tip of the shaft 46B of the piston 46 and the recess 45C of the movable valve seat 45 also becomes zero (S12 = 0). Then, when the input increases to the maximum load point input fb1 shown in FIG. 5 and reaches the full load point Kp, the pressure difference between the negative pressure chambers A and C and the variable pressure chambers B and D becomes maximum.

At this stage, even if the input shaft 13 is further depressed, the boosting effect due to the pressure difference cannot be exerted, and the output shaft 22 is substantially integrated with the input shaft 13 in a region where the output value is Fb1 or more. And is displaced in the axial direction. The input shaft 13 and the output shaft 22 reach the stroke end when the flange portion 22A contacts the stepped recess 2B of the front shell 2 shown in FIG.

On the other hand, when the brake operation is released,
When the input shaft 13 is pushed back in the direction of arrow E2 by the return spring 16, the movable valve seat 45 presses the poppet valve body 14 in the direction of arrow E2 against the weak spring 15 via the contact portion 45A. As shown in FIG. 4, the valve seat portion 41 of the valve body 41 is provided.
The poppet valve 14 is forcibly separated from C.

At this time, the shaft portion 46B of the reaction force piston 46
The gap S13 between the tip and the recess 45C of the movable valve seat 45 is
When the poppet valve element 14 is separated from the valve seat 7C of the valve body 7 with the gap S14 shown in FIG. 4, the gap is increased by the gap S14 from the gap S12 shown in FIG. Thus, a gap S13 (S13 = S12 + S14) shown in FIG. 4 is secured between the concave portion 45C of the movable valve seat 45 and the tip of the shaft portion 46B.

When the poppet valve element 14 separates from the valve seat 41C of the valve body 41, the negative pressure chambers A and C communicate with the variable pressure chambers B and D via the communication passages 8, 12 and the like. The negative pressure in the negative pressure chambers A and C is introduced into the variable pressure chambers B and D, and the negative pressure chambers A and C and the variable pressure chambers B and D become substantially equal at a pressure lower than the atmospheric pressure.

As a result, the output shaft 22 is pushed back in the direction of arrow F2 by the return spring 24 together with the valve body 41, and the output of the output shaft 22 falls within the range of the output value Fb1 shown in FIG. It decreases along 52B. And reaction disk 2
5 receives the reaction force from the output shaft 22 as a return force in the direction of arrow F2, and the reaction disk 25 continues to bulge into the collar 43 (stepped hole 42) as shown in FIG.

However, the movable valve seat 45 and the reaction force piston 4
6. The inner spring 50 and the outer spring 51 disposed between the stepped sleeve 49 and the stepped sleeve 49 are in a deformed state, and the reaction force piston 46 and the stepped sleeve 49 are directed toward the reaction disk 25 to respond to the reaction force. Since the pressing is continued by the applied elastic restoring force (spring force), the reaction disc 25
To prevent the reaction disk 25 from retreating toward the movable valve seat 45 together with the reaction force piston 46 and the stepped sleeve 49. it can.

Therefore, the input / output characteristics along the characteristic line 52 shown in FIG. 5 can be obtained when the brake operation is released, almost in the same manner as when the brake operation is performed. This can prevent the occurrence of hysteresis in the input / output characteristics. Then, when the brake operation is released, the stickiness of the brake pedal does not remain as in the related art, and problems such as a delay in releasing the brake can be solved.

Therefore, according to the present embodiment, it is possible to prevent the occurrence of hysteresis in the input / output characteristics as indicated by the characteristic line 52 shown in FIG. 5, and to quickly return the output shaft 22 to the initial position when the brake operation is released. As a result, the brake release operation can be performed promptly, the responsiveness at the time of releasing the operation can be enhanced, and the brake feeling can be improved.

At the time of normal brake operation,
By setting the pressing force (input) to the input shaft 13 within the range of the input values fa1 to fc1, the input / output characteristics having the first boosting ratio KA can be obtained along the characteristic line portion 52A shown in FIG. Output with normal depressing force (braking force from master cylinder)
Can be prevented from becoming excessive.

At the time of operating the emergency brake or the like, the input to the input shaft 13 is increased to the input value fc1 or more shown in FIG.
The input / output characteristics having the boosting ratio KB can be obtained, and the second boosting ratio KB at this time can be made larger than the first boosting ratio KA. As a result, the driver of the vehicle does not need to depress the brake pedal excessively strongly during emergency braking, and a sufficient braking force can be secured.

On the other hand, the stepped sleeve 49 is prevented from being removed from the flange 46A of the reaction force piston 46 by the step 49B.
By retaining the spring receiver 48 on the tip end side of the shaft portion 46B of the reaction force piston 46 by the retaining ring 47, the inner spring 50 and the outer spring 51 are maintained in a sub-assembled state on the outer peripheral side of the reaction force piston 46. It has a configuration. For this reason, the spring 50,
51 can be prevented from dropping from the outer peripheral side of the reaction force piston 46, and handling thereof can be simplified, and workability at the time of assembly can be improved.

Then, the reaction force piston 4 of the plunger 44
6, a spring receiver 48, a stepped sleeve 49, and an inner spring 5
The sub-assembly is formed together with the 0 and the outer spring 51, and these are assembled as a single unit body. Therefore, when assembling the plunger 44 into the stepped hole 42 of the valve body 41, the movable valve seat 45 is inserted into the stepped hole 42 from the direction of arrow E1 in FIG.
The unit body of the reaction force piston 46 is inserted into the stepped hole 42 from two directions.
The plunger 4 is inserted into the stepped hole 42 by inserting
4 can be easily assembled.

After the unit of the reaction force piston 46 is inserted into the stepped hole 42 of the valve body 41, the collar 43 is fitted into the stepped hole 42 from the side of the cylindrical projecting portion 41D, so that the unit is inserted. The body can be easily prevented from being pulled out, which also improves the workability during assembly.

Further, a plurality of types of collars 43 having different inner diameters are prepared in advance, and a plurality of types of unit bodies of the reaction force piston 46 are prepared in correspondence with these collars 43, so that the pressure receiving areas Ap and As are reduced. A plurality of different types of plungers 44 can be easily manufactured, and even if the other components of the pneumatic booster are the same, it is possible to easily cope with a change in the boost ratio and the like.

Next, FIG. 6 shows a second embodiment of the present invention. In this embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. It shall be. However, a feature of the present embodiment is that the boost ratio of the output to the input is changed in three stages as indicated by a characteristic line 61 shown in FIG.

Here, within the range of the characteristic lines 61A and 61B, the characteristic lines 52A and 52 described in the first embodiment are used.
As in 2B, input / output characteristics having boost ratios KA and KB can be obtained. However, in the present embodiment, before the input / output characteristics reach the full load point Kp as shown in FIG. 6, the flange 46A of the reaction force piston 46 is brought into contact with the step 49B of the stepped sleeve 49, and The clearance C2 illustrated in FIG. 3 and the like is set to zero (C2 = 0) when the input on the shaft 13 reaches the input value fd1.

Thus, in the present embodiment configured as described above, substantially the same operation and effect as in the first embodiment can be obtained. However, in this embodiment, particularly, the input reaches the input value fd1. Then, the output can be rapidly increased from the output value Fd1 to Fd2 (full load point Kp) along the characteristic line portion 61C, and the boost ratio of the output to the input can be changed in three stages. Become.

In the first embodiment, the flange 46A is provided on the outer periphery of the proximal end of the reaction force piston 46, and the step 49B is provided on the inner periphery of the stepped sleeve 49. However, the present invention is not limited to this. For example, at least one of the flange portion 46A and the step portion 49B may be eliminated, and the function of preventing the reaction force piston 46 and the stepped sleeve 49 from coming off may be adopted.

In each of the above embodiments, the first and second
A tandem-type pneumatic booster having negative pressure chambers A and C and transformer chambers B and D has been described as an example, but the present invention is not limited to this, and for example, a single-type pneumatic booster is used. It may be applied to.

[0104]

As described in detail above, according to the first aspect of the present invention, the plunger is free between the input shaft side member and the first and second output shaft side members when the brake is not operated. The first and second spring members are disposed in a long state, and the engaging portion formed on the outer peripheral portion of the second output shaft side member is brought into contact with the step portion of the valve body to thereby provide the input shaft. When the first output shaft-side member is relatively displaced with respect to the input shaft-side member at the time of pushing, the second output shaft-side member is restricted from being relatively displaced with respect to the valve body. For example, when the input shaft is pushed, the first and second
When the pressing operation is released, the first and second spring members can press the first and second output shaft-side members toward the reaction member, and the reaction member is moved to the input shaft side member. Relative displacement so as to retreat toward. Therefore, it is possible to prevent the occurrence of hysteresis in the input / output characteristics, and to improve the responsiveness at the time of canceling the pressing operation with respect to the input shaft.
For example, the brake release operation can be performed promptly,
Brake feeling can be improved.

When the input shaft is pushed, the first and second output shaft side members are relatively displaced in the valve body to obtain first the input / output characteristic having the first boost ratio. In the meantime, the first and second spring members can be elastically compressed and deformed. Then, at the stage where the locking portion of the second output shaft side member abuts the step portion of the valve body to regulate the relative displacement of the second output shaft side member with respect to the valve body, the first boosting ratio It is possible to obtain input / output characteristics having a larger second boost ratio. As a result, the boost ratio of the output to the input can be switched in a plurality of stages. For example, a sufficiently large braking force is generated as an output even in an emergency braking operation, and the operability of the brake can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a pneumatic booster according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a main part in FIG. 1 showing a plunger and the like.

FIG. 3 is an enlarged view similar to FIG. 2, showing the movement of a plunger during a brake operation.

FIG. 4 is an enlarged view similar to FIG. 2, showing the movement of the plunger when the brake operation is released.

FIG. 5 is a characteristic diagram showing input / output characteristics of the pneumatic booster according to the first embodiment.

FIG. 6 is a characteristic diagram showing input / output characteristics of a pneumatic booster according to a second embodiment.

FIG. 7 is a longitudinal sectional view showing a conventional pneumatic booster.

FIG. 8 is an enlarged view of a main part in FIG. 7 showing a plunger and the like.

FIG. 9 is a characteristic diagram showing input / output characteristics of a conventional pneumatic booster.

FIG. 10 is an enlarged view similar to FIG. 8, showing the movement of the plunger during a brake operation.

FIG. 11 is an enlarged view similar to FIG. 8, showing the movement of the plunger when the brake operation is released.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Casing 2 Front shell 3 Rear shell 4 Intermediate shell 5, 6 Power piston 8, 9, 12 Communication passage 13 Input shaft 14 Poppet valve 22 Output shaft 25 Reaction disk (reaction member) 41 Valve body 41A Large diameter part 41B Small diameter cylindrical part 41C Valve seat part 41E Step part 42 Stepped hole 43 Collar 44 Plunger 45 Movable valve seat (input shaft side member) 46 Reaction force piston (first output shaft side member) 48 Spring receiver 49 Stepped sleeve (second output) Shaft side member) 49A Flange part (locking part) 49B Step part 50 Inner spring (first spring member) 51 Outer spring (second spring member) A, C Negative pressure chamber (constant pressure chamber) B, D Transformation chamber KA and KB boost ratio

Claims (1)

[Claims] A power piston that is fixed to the casing at an outer peripheral side thereof and that defines a constant pressure chamber and a variable pressure chamber within the casing; and a power piston that is fixed to an inner peripheral side of the power piston, and A valve body capable of being displaced in the axial direction in conjunction with the displacement of the power piston, an input shaft provided with one end protruding outside one side of the casing and the other end inserted into the valve body, The variable pressure chamber is provided in the valve body for communicating with and blocking the gas from the variable pressure chamber and communicating and blocking the variable pressure chamber with the constant pressure chamber in cooperation with a poppet valve element provided in the valve body. A plunger that is displaced relative to the valve body by a pushing operation of the input shaft, one end of which is fitted to the valve body, and the other end of which is closer to the other side of the casing; An output shaft protruding to the outside, and one end side of the output shaft and the valve body, the valve body being pressed by the pressure difference between the variable pressure chamber and the constant pressure chamber when the input shaft is pushed. And a reaction member that transmits a part of the reaction force from the output shaft to the plunger, wherein the plunger is connected to the other end of the input shaft. And an input shaft side member for operating the poppet valve body, which is provided so as to be relatively displaceable with respect to the input shaft side member, and a reaction force from the output shaft when the input shaft is pushed. A first output shaft side member with which the reaction member abuts when transmitted to the reaction member; and a first output shaft movably relative to the input shaft side member and the first output shaft side member. On the side member When the reaction force from the output shaft is transmitted to the reaction member when the input shaft is pushed and the input shaft is pushed, the reaction member abuts, and a locking portion for the valve body is provided on the outer peripheral side. 2, the output shaft side member is disposed between the first output shaft side member and the input shaft side member, and the reaction force from the output shaft is transmitted to the reaction member when the input shaft is not pushed. If not, a first spring member interposed in a free length state between the first output shaft side member and the input shaft side member; and the second output shaft side member and the input shaft side member. Disposed between the second output shaft side member and the input shaft side member when the reaction force from the output shaft is not transmitted to the reaction member when the input shaft is not pushed. Second spring portion interposed in a free length state In the valve body, the reaction force from the output shaft is transmitted to the reaction member by the pushing of the input shaft, and the first output shaft side member is displaced relative to the input shaft side member. A step portion that abuts the locking portion of the second output shaft side member in the middle thereof and regulates the second output shaft side member from being relatively displaced with respect to the valve body. A pneumatic booster characterized in that: