JPH06171495A - Air pressure type servo unit - Google Patents

Abstract

PURPOSE:To increase a raising quantity of assisting force at the time of requiring a sudden deceleration without enlarging the size thereof by constituting this device so that an on-off valve is opened when a brake pedal is largely operated and thereby compressed air flows into a working pressure chamber via a passage. CONSTITUTION:When a brake pedal is operated in operated in order to secure the normal deceleration, an operation rod 18 moves in an output direction to a valve body 12, while an on-off valve 57 is left closed intact and a breather valve 33 is opened instead, whereby the atmosphere is introduced into a working pressure chamber 17, assisting the input of this operation rod 18. If the brake pedal is operated by force of more than the specified value, the on-off valve 57 opens and a passage 47 opens too, so that compressed air in an air pump 41 is introduced into the working pressure chamber 17, therefore differential pressure is produced in a power piston at a high velocity. When the brake pedal is yet largely operated, pressure in the working pressure chamber 17 goes beyond atmospheric pressure till it becomes the same pressure as that in a compressed air chamber 44, so the extent of yet larger differential pressure acts on the power piston 8.

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 assists a brake operating force in a vehicle or the like and outputs it to a master cylinder.

[0002]

2. Description of the Related Art A conventional pneumatic booster divides the inside of a shell into a negative pressure chamber communicating with a negative pressure source and an operating pressure chamber, and is slidably supported at one end of the shell in a valve body. Power piston and a poppet valve for introducing atmospheric air into the working pressure chamber by relative movement of the operating rod connected to the brake pedal in the output direction with respect to the valve body, which is provided in the valve body. By introducing atmospheric air into the chamber, a differential pressure is generated in the power piston to assist and output the input from the operating rod.

[0003]

However, in the above pneumatic booster, there is a limit to the magnitude of the assisting force that is determined by the pressure difference between the atmospheric pressure and the negative pressure generated on both sides of the power piston. When it is necessary to guarantee the braking performance, the size of the power piston that receives the differential pressure, that is, the size of the pneumatic booster as a whole, or the size of the negative pressure chamber and the working pressure chamber are provided in two pairs. It is necessary to adopt a tandem booster or the like, and there is a problem that the size is increased in any case. Further, since the amount of the atmosphere introduced into the working pressure chamber is almost constant, the assisting force will rise almost constantly even when the speed is to be rapidly reduced.

Therefore, an object of the present invention is to provide a pneumatic booster capable of increasing the assisting force without increasing the size and increasing the amount of increase in the assisting force when the speed is rapidly reduced. Is to provide.

[0005]

In order to achieve the above object, the pneumatic booster according to claim 1 of the present invention comprises a negative pressure chamber and an operating pressure chamber that communicate with the negative pressure source in the shell. A power piston slidably supported on one end side of the shell in the valve body portion, and an output rod relative to the valve body portion of an operating rod provided in the valve body portion and connected to a brake pedal. A poppet valve for introducing atmospheric air into the operating pressure chamber by movement, and generating a differential pressure in the power piston by introducing atmospheric air into the operating pressure chamber to assist and output the input of the operating rod. A compressed air source for generating compressed air, a flow path connecting the compressed air source and the working pressure chamber, and the flow path, The relative amount of movement in the output direction of the operating rod relative Rububodi unit is characterized by including a closing valve which opens and reaches a predetermined value.

According to a second aspect of the present invention, in addition to the structure of the first aspect, the pneumatic booster is provided outside the portion of the valve body portion projecting from the shell. A cover that slidably supports and that defines a compressed air chamber that is connected to the compressed air source and that is filled with compressed air inside with the shell, and connects the compressed air chamber and the working pressure chamber. A flow passage is provided in the valve body portion, and the opening / closing valve is provided in the flow passage.

Further, in the pneumatic booster according to claim 3 of the present invention, in addition to the pneumatic booster according to claim 1 or 2, the on-off valve is an output direction of the operating rod of the poppet valve. It is characterized in that it is provided in series on the side.

[0008]

According to the pneumatic booster of the first aspect of the present invention, in order to obtain a normal deceleration, the brake pedal is depressed and the operating rod connected to the brake pedal is output in the output direction with respect to the valve body. When the poppet valve introduces air into the working pressure chamber to generate a differential pressure in the power piston and assists the input of the operating rod to output, a sudden deceleration during or without brake operation. In order to obtain, when the brake pedal is depressed with a large force, the relative movement amount of the operating rod in the output direction with respect to the valve body portion reaches a predetermined value (for example, the relative movement position moves until it is close to the limit position), The on-off valve opens to introduce compressed air from the compressed air source that generates compressed air into the working pressure chamber through the flow path. It becomes door. As a result, a pressure difference is generated in the power piston at a speed faster than the normal introduction of the atmosphere. Further, when the operating pressure chamber reaches the atmospheric pressure, the brake pedal is depressed in order to obtain a larger deceleration, and the relative movement amount of the operating rod in the output direction with respect to the valve body portion reaches a predetermined value (for example, relative movement). Position is near the limit position),
The on-off valve opens, and compressed air is introduced from the compressed air source that generates compressed air into the working pressure chamber through the flow path. As a result, the pressure in the working pressure chamber exceeds the atmospheric pressure, and a larger differential pressure acts on the power piston.

Further, according to the pneumatic booster of the second aspect of the present invention, in addition to the function of the first aspect, the valve body is supported by the shell, and Since it is also supported by the cover provided outside the portion protruding from the shell, the support becomes more stable. Further, a compressed air chamber defined by the cover and the shell is filled with compressed air, and a flow passage for connecting the compressed air chamber and the working pressure chamber is provided in the valve body portion, and an opening / closing valve is provided in the flow passage. Since the flow path for introducing compressed air into the working pressure chamber is shortened, the responsiveness is further improved.

Further, according to the pneumatic booster of the third aspect of the present invention, in addition to the operation of the first or second aspect, the opening / closing valve is the poppet valve side of the operating rod in the output direction. It is not necessary to expand the valve body portion in the radial direction because it is provided in series.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A pneumatic booster according to a first embodiment of the present invention will be described below with reference to FIG. The output direction in the following description indicates the output direction of the pneumatic booster (left direction in the figure), and the counter output direction indicates the counter output direction of the pneumatic booster (right direction in the figure). Is.

In the figure, reference numeral 1 indicates a pneumatic booster, and the pneumatic booster 1 has a shell 2. The shell 2 is composed of a front shell 4 in which a master cylinder (not shown) is attached to the outside of the end face portion 3 on the output direction side, and a rear shell 5 which is airtightly fitted on the opposite output side of the front shell 4. The rear shell 5 has a seal / support member 7 made of an elastic material in a fitting hole 6 formed at the end portion on the opposite output side thereof, and the power piston 8 slides on the seal / support member 7. It is supported freely.

The power piston 8 has a flange portion 9 located inside the shell 2 and a large diameter portion 10 which is provided on the side opposite to the output direction of the flange portion 9 and which is slightly smaller than the flange portion 9 supported by the seal / support member 7. And a valve body portion 12 having a stepped bottom and having a cylindrical shape with a bottom and a stepped bottom portion which is provided on the side opposite to the output side of the large diameter portion 10 and protrudes to the outside of the shell. 9 is a plate portion 13 having a circular plate shape with a hole, the inner peripheral side of which is fixed to 9 and extends outward in the radial direction, and the inner peripheral portion is airtightly supported by the flange portion 9 while being provided on the counter output direction side of the plate portion 13. Further, the shell 2 has a partition member 14 made of an elastic material whose outer peripheral portion is airtightly supported. Due to these, the inside of the shell 2 is hermetically sealed to the negative pressure chamber 16 on the output direction side, which communicates with a negative pressure source (not shown) via the negative pressure communication pipe 15, and the working pressure chamber 17 on the opposite output direction side. It is partitioned.

Further, the other end output side of an operating rod 18, one end of which is connected to a brake pedal (not shown), is inserted into the opening of the valve body 12 on the side of the small diameter portion 11, and the output of the operating rod 18 is inserted. An elastically deformable poppet valve 21 is provided on the direction side via springs 19 and 20, and a valve plunger 22 arranged in series with the poppet valve 21 is engaged with the tip end portion thereof. In addition, the valve plunger 22
An output shaft 24 is provided on the output direction side of the through a reaction disk 23 made of an elastic material having a diameter larger than the output shaft 24. The output shaft 24 extends from an insertion hole 25 provided in the front shell 4 to a front seal 26. The end is projected in the state of being sealed by and the power piston 8 is moved toward the output direction to output to the master cylinder (not shown). Further, a return spring 27 is provided between the front shell 4 and the power piston 8 for urging the power piston 8 in a counter output direction with a predetermined urging force. The move is
The limit position is regulated by abutting on the protrusion 28 formed on the rear shell 5.

The valve body portion 12 is formed with a negative pressure passage 29 communicating with the negative pressure chamber 16 and an operation passage 32 communicating with the working pressure chamber 17. The poppet valve 21 is
The communication between the negative pressure flow passage 29 and the working flow passage 32 is blocked by sitting on the contact portion 31 formed at the bottom of the valve body portion 12 (the valve constituted by the poppet valve 21 and the contact portion 31 is (Negative pressure valve 30), and valve body 12
Communication between the opening side of the valve and the working flow path 32
The valve 2 is seated at the end on the side opposite to the output direction to shut off the valve (a valve including the poppet valve 21 and the valve plunger 22 is referred to as an atmospheric valve 33).

The poppet valve 21 has the negative pressure valve 30 open and the atmosphere valve 33 closed, that is, the working pressure chamber 17 when the power piston 8 is in the non-actuated state and at the movement limit position in the opposite output direction. It is in a state of being communicated with the negative pressure chamber 16. When the operating rod 18 receives an input and the operating rod 18 and the valve plunger 22 move relative to the valve body portion 12 in the output direction, the contact portion 31 of the valve body portion 12 is first contacted to close the negative pressure valve 30. The communication between the working pressure chamber 17 and the negative pressure chamber 16 is interrupted, and the movement is restricted by the contact portion 31, so that the working pressure chamber 17 is opened to the atmosphere by separating from the moving valve plunger 22 and opening the atmosphere valve 33. It is designed to communicate with. Further, from this state, the input of the operating rod 18 is loosened, and the valve plunger 22 and the operating rod 18 are moved to the valve body portion 12 by the reaction force transmitted from the master cylinder side (not shown) via the output shaft 24 and the reaction disc 23. On the other hand, when relatively moving in the direction opposite to the output direction, the valve plunger 22 is first contacted to close the atmospheric valve 33,
Next, the negative pressure valve 30 is opened apart from the contact portion 31 of the valve body portion 12.

The valve plunger 22 is formed with a groove portion 35, which has a predetermined width larger than that of the stopper plate 34, for locking one end side of a stopper plate 34 of a predetermined width extending in the orthogonal direction. The other end of the plate 34 is formed in the large-diameter portion 10 of the valve body portion 12 and has a groove 3 having a width larger than the stopper plate 34 by a predetermined amount.
6, the stopper plate 34 restricts the range of relative movement of the valve plunger 22 with respect to the valve body portion 12. The groove portion 36 constitutes a part of the working flow path 32.

In the first embodiment, a cover 37 having an outermost diameter substantially equal to that of the rear shell 5 is airtightly fixed to the rear shell 5 outside the valve body 12 protruding from the rear shell 5 on the output direction side. It is provided in the opened state. The cover 37 has a shape having three cylindrical portions whose diameters gradually decrease in the opposite output direction, and the cover 37 is elastic in a fitting hole 38 formed at the end portion on the opposite output direction side. A seal / support member 39 made of a material is provided, and the small-diameter portion 11 of the valve body 12 is slidably supported by the seal / support member 39. The cover 37 is provided with a communication pipe 43 that is connected to an air pump 41, which is a compressed air source that generates compressed air by driving the motor 40, via an external pipe 42. The space defined by the rear shell 5 constitutes a compressed air chamber 44 filled with compressed air. Here, the external pipe 42 is provided with a check valve 45 that prevents the reverse flow of the compressed air toward the air pump 41.

The compressed air chamber 44 or the external pipe 42
A pressure sensor (not shown) is provided closer to the compressed air chamber 44 than the check valve 45, and a control unit (not shown) controls the pressure in the compressed air chamber 44 from atmospheric pressure by a signal from the pressure sensor. The motor 40 is drive-controlled so as to always maintain a high predetermined value.

On the side surface 46 of the valve body 12 on the output side of the groove 36, a part of the working flow passage 32 on the side communicating with the working pressure chamber 17 is provided with an opening at one end. The flow path 4 that connects the compressed air chamber 44 and the groove 36 to each other.
7 has an opening at one end. A recess 49 is formed on the side surface on the output direction side of the stopper plate 34 so as to face the range including both openings and is recessed by one step. The stopper plate 34 is formed on the side surface 46 of the valve body portion 12.
A seal ring 50 made of an elastic material is fitted so as to face the outside of the recess 49.

A valve chamber 51 is provided in the flow path 47, and in the valve chamber 51, a projection 52 provided so as to project toward the groove 36 from an opening facing the recess 49 and a valve. Room 5
1, a valve body 55 including a valve portion 54 that is seated on the seat portion 53 on the side opposite to the output direction to close the flow path 47, and the valve portion 54 provided on the output side of the valve body 55 is mounted on the seat portion 53 An opening / closing valve 57 including a spring 56 for urging the valve body 55 to be seated is provided. In the on-off valve 57, the stopper plate 34 moves to the vicinity of the movement limit position in the output direction with respect to the valve body portion 12 and comes into contact with the seal ring 50, and then the projection 52 comes into contact with the bottom surface of the recess 49, and a further stopper. The plate 34 is pressed by the movement and moves against the biasing force of the spring 56 to separate the valve portion 54 from the seat portion 53 and open the flow path 47.

The balance between the input to the operating rod 18 and the reaction force from the return spring 27 and the master cylinder side (not shown) is such that the stepping force for obtaining a normal deceleration is input to the brake pedal. Valve body portion 12 of the operating rod 18
The relative movement range with respect to is set to a predetermined range in which the stopper plate 34 does not contact the seal ring 50 and the opening / closing valve 57 is not opened. Further, in order to obtain a larger deceleration when the pedaling force for obtaining a rapid deceleration is input to the brake pedal (so-called spike braking) and after the full load point (the point where the working pressure chamber 17 becomes atmospheric pressure). If the brake pedal is depressed,
When the relative movement position of the operating rod 18 with respect to the valve body portion 12 exceeds the predetermined range and reaches the vicinity of the movement limit position, the stopper plate 34 causes the seal ring 50 to move.
And the opening / closing valve 57 is opened.

In the pneumatic booster 1 of the first embodiment having the above-described structure, the negative pressure valve 30 is opened and the atmospheric valve 33 is closed in a non-operating state in which the brake pedal (not shown) is not depressed. From this state, when the brake pedal is depressed to obtain a normal low deceleration, the operating rod 18 connected to the brake pedal is depressed.
And the valve plunger 22 moves relative to the valve body 12 in the output direction within the above-mentioned predetermined range. Then,
The poppet valve 21 first contacts the contact portion 31 of the valve body portion 12 to close the negative pressure valve 30, and then the valve plunger 22 is separated from the poppet valve 21 to release the atmospheric valve 33.
To open the working flow passage 32 to the opening side of the valve body portion 12 to introduce the atmosphere into the working pressure chamber 17, and to generate a differential pressure on both sides of the plate portion 13 of the power piston 8 to input the operating rod 18. Is output to the master cylinder side (not shown) from the output shaft 24.

During the brake operation or when the brake is not operated, the operating rod 18 and the valve plunger 22 exceed the predetermined range in the output direction with respect to the valve body 12 in order to obtain a rapid deceleration which is not normally obtained. When the brake pedal is depressed with a large force that relatively moves until reaching the vicinity of the movement limit position, the negative pressure valve 30 is closed and the atmospheric valve 33 is opened as described above, or the negative pressure valve 30 is closed and the atmospheric valve 33 is closed. After the valve is opened, the stopper plate 34 locked to the valve plunger 22 comes into contact with the seal ring 50 and the working flow path 32
The valve portion 54 is separated from the seat portion 53 by contacting the projection 52 of the valve body 55 and pressing the same while blocking the communication of the flow path 4
Open seven. Then, the flow path 47 and the stopper plate 34
The compressed air chamber 44 and the working pressure chamber 17 communicate with each other through a space surrounded by the seal ring 50 and a part of the working flow passage 32 on the working pressure chamber 17 side that is blocked, and the compressed air is pressurized to the working pressure. It will be introduced into the chamber 17. As a result, a differential pressure is generated in the power piston 8 at a speed faster than the normal introduction of the atmosphere. The flow passage 47 formed in the valve body portion 12, the space portion, and the blocked working flow passage 3
A part of the second working pressure chamber 17 side constitutes a flow path connecting the compressed air chamber 44 and the working pressure chamber 17, and the flow path, the compressed air chamber 44 and the external pipe 42 form a compressed air source. A flow path for connecting the air pump 41 and the working pressure chamber 17 is configured.

Further, when the brake operation is performed to obtain a normal deceleration and the working pressure chamber 17 becomes the atmospheric pressure (full load point), the brake pedal is depressed to obtain a larger deceleration, and the operating rod is depressed. When the valve 18 and the valve plunger 22 move in the output direction with respect to the valve body 12 beyond the predetermined range to the vicinity of the movement limit position, the negative pressure valve 30 is closed and the atmosphere valve 33 is opened as described above. The stopper plate 34 locked to the plunger 22 abuts on the seal ring 50 and blocks the communication of the working flow passage 32, and abuts against the protrusion 52 of the valve body 55 to press the same, thereby seating the valve portion 54. The flow path 47 is opened apart from the portion 53 to communicate the compressed air chamber 44 with the working pressure chamber 17, and the compressed air is introduced into the working pressure chamber 17. As a result, the pressure in the working pressure chamber 17 exceeds the atmospheric pressure and rises to almost the same pressure as the compressed air chamber 44, and a larger differential pressure acts on the power piston 8.

Of course, in order to obtain a rapid deceleration, the brake pedal is depressed with a large force that the operating rod 18 and the valve plunger 22 move with respect to the valve body portion 12 in the output direction beyond the above predetermined range to the vicinity of the movement limit position. If continued, stopper plate 34
Keeps the on-off valve 57 open, the compressed air continues to be introduced into the working pressure chamber 17, so that the pressure in the working pressure chamber 17 rises by a large increase amount, exceeds the atmospheric pressure, and is compressed above the atmospheric pressure. The pressure rises to almost the same pressure as the air chamber 44.

According to the pneumatic booster 1 of the first embodiment described above, when an ordinary low deceleration is to be achieved, the atmosphere is introduced into the working pressure chamber 17 without opening the on-off valve 57. As a result, the brake reaction does not become hypersensitive, and when a rapid deceleration that is not normally obtained is to be obtained, the opening / closing valve 57 is opened and compressed air is supplied to the working pressure chamber 17. Since it will be introduced, the differential pressure will be generated in the power piston 8 at a speed faster than the introduction of normal atmosphere,
The amount of increase in the assistance force becomes large. Therefore, the responsiveness is excellent.

Further, when an even larger deceleration is to be obtained when the working pressure chamber 17 reaches the atmospheric pressure, the opening / closing valve 57 is opened to introduce compressed air into the working pressure chamber 17. As a result, the pressure in the working pressure chamber 17 exceeds the atmospheric pressure, and a larger differential pressure acts on the power piston 8. Therefore, it is possible to increase the assisting force and increase the upper limit of the boosting action without increasing the size.

Further, the valve body portion 12 is supported by the shell 2 at the large diameter portion 10 and the small diameter portion 11.
Since it is also supported by the cover 37 at, the support becomes more stable. Moreover, the compressed air chamber 44 defined by the cover 37 and the shell 2 is filled with compressed air, and a flow path connecting the compressed air chamber 44 and the working pressure chamber 17 is provided in the valve body portion 12, and Since the opening / closing valve 57 is provided in the flow path, the flow path for introducing the compressed air into the working pressure chamber 17 is shortened, and the responsiveness is further improved.

Next, a pneumatic booster according to a second embodiment of the present invention will be described below with reference to FIGS. 2 and 3 focusing on parts different from the first embodiment. The same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the pneumatic booster 1 of the second embodiment, the valve body portion 12 of the power piston 8 has a stepped shape including a flange portion 9 on the output direction side and a small diameter portion 11 on the opposite output side. The small diameter portion 11 is slidably supported by the seal / support member 7 of the rear shell 5. Also, cover 3
7 has a shape having two cylindrical portions whose diameter decreases in the opposite output direction, and the small diameter portion 1 of the valve body portion 12 is attached to the seal / support member 39 at the end portion on the opposite output direction side.
1 is slidably supported.

As shown in FIG. 3, a substantially U-shaped stopper plate 34 is locked to the valve plunger 22, and seal members 60 and 61 are provided on both sides of a groove 35 that locks the stopper plate 34. Is provided. These seal members 60 and 61 allow the air in the compressed air chamber 44 to flow to the outer peripheral side of the valve plunger 22 from a hole 62 formed in the valve body 12 so as to insert the stopper plate 34 through the compressed air chamber 44. It is intended to prevent leakage through the gap, and the valve plunger 22 is formed with a part of the working flow path 32 in a state where both end openings 63 and 64 are provided on both outer sides of the seal members 60 and 61, respectively. The opening 64 on the output direction side communicates with the working pressure chamber 17 through a through hole 32a formed in the bottom of the valve body 12 and forming a part of the working flow passage 32.

An annular groove portion 65 is formed on the output side of the valve plunger 22 further toward the output side than the output side opening 64. The annular groove portion 65 is formed by a spring 66 in the output direction side. An elastically deformable annular valve portion that abuts the annular convex portion 65a formed on the end surface on the output direction side of the annular groove portion 65 in a biased state and airtightly partitions the space 68 in the annular groove portion 65 from the outside. 67 is provided so as to partially project outward in the radial direction, and the space portion 68 inside the annular valve portion 67, the groove portion 35, and the hole portion 62 are provided.
And are communicated with each other by a flow path 69 formed in the valve plunger 22. Further, when the brake pedal (not shown) is stepped on the valve body portion 12 to obtain a rapid deceleration which is not normally obtained, the valve plunger 22 moves to come into contact with the annular valve portion 67 and move. Regulate the
A restricting portion 70 that separates the annular valve portion 67 from the annular convex portion 65a of the annular groove portion 65 is provided so as to project inward in the radial direction. The annular valve portion 67 and the spring 66 compose the opening / closing valve 71 in the second embodiment.

The position of the movement limit of the power piston 8 on the side opposite to the output direction is regulated by the stopper plate 34 abutting against the cover 37. In this state, both the atmosphere valve 33 and the negative pressure valve 30 are closed. It is in a state of When an input is made from the brake pedal, the atmospheric valve 33 is opened by the relative movement of the operating rod 18 in the output direction, and when the brake pedal is loosened, the atmospheric valve 33 is moved by the relative movement of the operating rod 18 in the opposite output direction. After the valve 33 is closed, the negative pressure valve 30 is opened, and the working pressure chamber 17 and the negative pressure chamber 16 have almost the same pressure.
Both pressures are balanced and the negative pressure valve 30 is closed.

In the pneumatic booster 1 of the second embodiment having the above structure, both the negative pressure valve 30 and the atmospheric valve 33 are closed when the brake pedal is not depressed, and this state is set. When the brake pedal is depressed in order to obtain a normal low deceleration, the operating rod 18 and the valve plunger 22 connected to the brake pedal move relative to the valve body portion 12 in the output direction within a predetermined range. Then, the valve plunger 2
2 is separated from the poppet valve 21 to open the atmosphere valve 33 to communicate the working flow path 32 with the opening side of the valve body portion 12 to introduce the atmosphere into the working pressure chamber 17 and to power the piston 8
A differential pressure is generated on both sides of the plate portion 13 to assist the input of the operating rod 18 and output from the output shaft 24 to the master cylinder side (not shown).

During the operation of the brake or when the brake is not operated, the operating rod 18 and the valve plunger 22 exceed the predetermined range in the output direction with respect to the valve body 12 in order to obtain a rapid deceleration which is not normally obtained. When the brake pedal is depressed with a large force to move to the vicinity of the movement limit position, the valve plunger 22
The movement of the annular valve portion 67 provided on the output direction side of the valve body portion is regulated in a state where the annular valve portion 67 abuts on the regulation portion 70 of the valve body portion 12 and blocks the communication of the working flow passage 32. When the valve plunger 22 further moves, the annular valve portion 67 contracts against the urging force of the spring 66 and separates from the annular convex portion 65a of the annular groove portion 65, opens the space portion 68, and opens the hole 6
2, the groove 35, the flow path 69, the space 68, and a part of the blocked working flow path 32 on the working pressure chamber 17 side.
And the working pressure chamber 17 are communicated with each other, and compressed air is supplied with the working pressure chamber 17
Will be introduced to. The hole 62 and the groove 3
5, the flow path 69, the space 68, and the blocked working flow path 3
A part of the second working pressure chamber 17 side constitutes a flow path connecting the compressed air chamber 44 and the working pressure chamber 17, and the flow path, the compressed air chamber 44 and the external pipe 42 form a compressed air source. A flow path for connecting the air pump 41 and the working pressure chamber 17 is configured.

Further, when the brake operation is performed to obtain a normal deceleration and the working pressure chamber 17 becomes the atmospheric pressure (full load point), the brake pedal is depressed to obtain a larger deceleration, and the operating rod is depressed. When the valve 18 and the valve plunger 22 move in the output direction with respect to the valve body 12 beyond the predetermined range to the vicinity of the movement limit position, the annular valve portion 67 provided on the output direction side of the valve plunger 22 of the valve body portion 12 moves. The movement is regulated in a state of contacting the regulation portion 70 and blocking the communication of the working flow path 32. The further movement of the valve plunger 22 causes the annular valve portion 67 to contract against the urging force of the spring 66 and separate from the annular convex portion 65a of the annular groove portion 65, thereby opening the space portion 68 and opening the compressed air chamber 44. And the working pressure chamber 17 are communicated with each other, and compressed air is introduced into the working pressure chamber 17.

Of course, in order to obtain a rapid deceleration, the brake pedal is depressed with a large force that the operating rod 18 and the valve plunger 22 move with respect to the valve body portion 12 in the output direction beyond the above predetermined range to the vicinity of the movement limit position. If it continues to operate, the on-off valve 71 continues to maintain the open state, so that compressed air is continuously introduced into the working pressure chamber 17, so that the pressure in the working pressure chamber 17 rises by a large increase amount and exceeds the atmospheric pressure. The pressure in the compressed air chamber 44, which is higher than the atmospheric pressure, rises to almost the same pressure.

As described above, according to the pneumatic booster 1 of the second embodiment, the same effect as that of the first embodiment can be obtained, and of course, the valve plunger 22 arranged in series on the output side of the poppet valve 21. Further, the on-off valve 71 is connected in series on the output side.
Since it is not necessary to expand the valve body portion 12 in the radial direction, the force that the valve body portion 12 receives from the compressed air chamber 44 can be reduced, and the spring load of the return spring 27 can be reduced. You can

In both the first and second embodiments, the on-off valve 5 is operated when the operating rod 18 and the valve plunger 22 relatively move with respect to the valve body portion 12 in the vicinity of the movement limit position in the output direction.
7 and 71 are configured to be opened, but they do not necessarily have to be opened in the vicinity of the movement limit position as long as they are opened when a predetermined range of relative movement such as for obtaining the normal low deceleration described above is exceeded.

[0041]

As described in detail above, the first aspect of the present invention
According to the pneumatic booster described, when trying to obtain a normal low deceleration, the reaction of the brake does not become hypersensitive because the atmosphere is introduced into the working pressure chamber, and it is usually obtained. When trying to obtain a rapid deceleration, the on-off valve is opened and compressed air is introduced into the working pressure chamber, so the differential pressure is generated at a speed faster than the introduction of normal air into the power piston. Therefore, the amount of increase in the supporting force becomes large. Therefore, the responsiveness is excellent. Further, when trying to obtain a larger deceleration when the working pressure chamber reaches the atmospheric pressure, the opening / closing valve is opened and the compressed air is introduced into the working pressure chamber. Since the pressure in the pressure chamber exceeds the atmospheric pressure and a larger differential pressure acts on the power piston, the assisting force can be increased and the upper limit value of the boosting action can be increased without increasing the size.

According to the pneumatic booster of the second aspect of the present invention, in addition to the effect of the first aspect, the valve body is supported by the shell and also by the cover. Therefore, the support will be more stable. Moreover, the compressed air chamber defined by the cover and the shell is filled with compressed air, and a flow path for connecting the compressed air chamber and the working pressure chamber is provided in the valve body portion, and the opening / closing valve is provided in the flow path. Since the flow path for introducing compressed air into the working pressure chamber is shortened, the responsiveness is further improved.

Further, according to the pneumatic booster of the third aspect of the present invention, in addition to the effect of the first or second aspect, the opening / closing valve is the poppet valve side of the operating rod in the output direction. Since it is installed in series, it is not necessary to expand the valve body in the radial direction, so the force that the valve body receives from the compressed air chamber can be reduced and the spring load of the return spring can be reduced. .

[Brief description of drawings]

FIG. 1 is a sectional view showing a pneumatic booster according to a first embodiment of the present invention, showing a non-operating state.

FIG. 2 is a sectional view showing a pneumatic booster according to a second embodiment of the present invention, showing a non-operating state.

FIG. 3 is a partially enlarged cross-sectional view showing the vicinity of an opening / closing valve of a pneumatic booster according to a second embodiment of the present invention, showing a non-operating state.

[Explanation of symbols]

 1 Atmospheric pressure booster 2 Shell 8 Power piston 12 Valve body 16 Negative pressure chamber 17 Working pressure chamber 18 Operating rod 21 Poppet valve 37 Cover 41 Air pump (compressed air source) 44 Compressed air chamber 57,71 Open / close valve

Claims (3)

[Claims] 1. A power piston which divides the inside of a shell into a negative pressure chamber communicating with a negative pressure source and an operating pressure chamber, and which is slidably supported on one end side of the shell in a valve body portion, and the valve body. And a poppet valve for introducing atmospheric air into the working pressure chamber by relative movement of an operating rod connected to the brake pedal in the output direction with respect to the valve body portion, and introducing atmospheric air into the working pressure chamber. In the pneumatic booster that generates a differential pressure in the power piston to assist and output the input of the operating rod, a compressed air source for generating compressed air, the compressed air source and the working pressure chamber And a flow path that connects the valve body and the relative movement of the operating rod in the output direction with respect to the valve body portion. A pneumatic booster, comprising: an opening / closing valve that opens when the amount reaches a predetermined value. 2. A compressed air chamber for slidably supporting the valve body portion outside the portion of the valve body portion projecting from the shell and being connected to the compressed air source and filled with compressed air therein. Is provided with the shell, a flow path connecting the compressed air chamber and the working pressure chamber is provided in the valve body portion, and the opening / closing valve is provided in the flow path. The pneumatic booster according to claim 1. 3. The on-off valve of the poppet valve,
The pneumatic booster according to claim 1 or 2, wherein the operating booster is provided in series on the output side of the operating rod.