JPH0589138U - Pneumatic booster - Google Patents

Abstract

(57) [Summary] [Structure] An outer space portion 80 between the boot 76 and the outer peripheral portion of the valve body portion 23, and an inner space portion between the valve mechanism 22 and the atmosphere passage member 75 in the valve body portion 23. A communication passage 81 for communicating with 82 is provided. [Effect] In the initial stage of the boosting operation for introducing the atmosphere, in addition to the atmosphere stored in the inner space portion 82, the outer space portion 80
The atmosphere stored in the inner space portion 82 and the outer space portion 80
Since the atmosphere stored in the communication passage 81 that communicates with and is introduced into the working pressure chamber 19, the power piston immediately operates and a delay may occur in the rise of the output of the pneumatic booster. It will be excellent in responsiveness.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a pneumatic booster that assists the operation of a master cylinder or assists the depression of a clutch in a vehicle or the like in response to a brake operation or the like.

[0002]

[Prior Art]

 As a conventional pneumatic booster, the one having the configuration illustrated in FIG. 3 is adopted. The pneumatic booster 100 slides on a housing 103 having a front shell 101 and a rear shell 102, and a valve body 105 having a substantially bottomed cylindrical shape in a fitting insertion hole 104 provided in the rear shell 102 of the housing 103. A power piston 107, which is freely inserted and provided with an atmospheric air introduction passage 106 for introducing atmospheric air on the inner peripheral side of the valve body 105, and a valve plunger chamber provided on the bottom 108 of the valve body 105. It has a valve plunger 110 inserted into 109 and an operating rod 111 which is connected to the valve plunger 110 and operates according to an input of a pedal. Further, the power piston 107 supports the inner peripheral side thereof and a housing. The outer peripheral portion is supported by 103, and the inside of the housing 103 is fronted. A diaphragm 114 which divides the negative pressure chamber 112 on the side of the shell 101 and an operating pressure chamber 113 on the side of the rear shell 102, a seat surface 115 provided on the valve plunger 110, and a seat surface 116 provided on the valve body 105. A valve mechanism 118 which is composed of a poppet valve 117 which is seated on and off of the seat surfaces 115 and 116 and which connects and disconnects the working pressure chamber 113 and the negative pressure chamber 112 and also connects and disconnects the working pressure chamber 113 and the atmosphere. And have.

In the air introduction passage 106 of the valve body portion 105, a filter member for preventing dust and the like in the atmosphere from entering the valve body portion 105 and a silencer member for suppressing the generation of sound when the air is introduced. The atmosphere passage member 119 made of at least one of the above is provided.

[0004]

[Problems to be solved by the device]

 However, the pneumatic booster 100 is introduced into the negative working pressure chamber 113 via the valve mechanism 118 by the intake resistance when passing through the atmosphere passing member 119, especially in the initial state of the boosting operation. However, there is a problem that the response of the power piston 107 is slow, that is, the output of the pneumatic booster 100 rises slowly due to a shortage of atmospheric air. Then, in order to solve this problem, an attempt was made to improve the material of the air passage member 119 which becomes the intake resistance, but the improvement of the responsiveness by this improvement was limited.

Therefore, it is an object of the present invention to provide a pneumatic booster which has a fast responsiveness, particularly in the initial state of boosting operation, and which has excellent responsiveness.

[0006]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the pneumatic booster of the present invention is supported by a housing in a slidable manner in a valve body, and at the same time, an atmospheric air is introduced to the inner peripheral side of the valve body. A power piston provided with an introduction passage, a diaphragm partitioning the inside of the housing together with the power piston into a negative pressure chamber communicating with a negative pressure source and an operating pressure chamber selectively communicating with the negative pressure chamber or the atmosphere. A valve mechanism provided on the inner peripheral side of the valve body portion for controlling the communication between the working pressure chamber and the negative pressure chamber and the communication between the working pressure chamber and the atmosphere, and an operating mechanism for operating the valve mechanism. A rod, an output shaft that is output by the power piston that moves due to the differential pressure between the negative pressure chamber and the working pressure chamber, and an outer peripheral portion of the valve body that protrudes from the housing. An outer space portion is provided between the outer circumference portion and the outer circumference portion, and the boot portion expands and contracts according to the sliding movement of the valve body portion. The atmosphere introduction passage has at least one of a filter member and a silencer member. An atmosphere passage member consisting of one of the above is provided, and a communication passage is provided to connect the outer space portion and the inner space portion between the valve mechanism in the valve body portion and the atmosphere passage member. It is characterized by becoming.

[0007]

[Action]

 According to the pneumatic booster of the present invention, the valve body has already passed through the atmosphere passing member (that is, the intake resistance due to the atmosphere passing member is not received) at the initial stage of the boosting operation for introducing the atmosphere. In addition to the atmosphere stored in the inner space between the valve mechanism and the atmosphere passage member, the outside between the boot and the outer periphery of the valve body that has also passed through the atmosphere passage member. The atmosphere stored in the space portion and the atmosphere stored in the communication passage that connects the inner space portion and the outer space portion are introduced into the working pressure chamber. Therefore, the atmosphere that has passed through the atmosphere passage member is sufficiently stored, and this atmosphere is introduced into the working pressure chamber at the initial stage of boosting operation, so that the power piston immediately operates and the pneumatic booster is activated. There is no delay in the rise of the device output.

[0008]

【Example】

 A pneumatic booster according to a first embodiment of the present invention will be described below with reference to FIG. It should be noted that the left and right in the following description use the left and right in the drawings for convenience.

In the figure, reference numeral 1 is a pneumatic booster, reference numeral 2 is a front shell in which a master cylinder (not shown) is provided on a left side surface portion 3, reference numeral 4 is a right shell of the front shell 2 and is fitted to the front shell. 2, a rear shell constituting a housing 5, reference numeral 6 is a power piston slidably supported on the housing 5, and reference numeral 7 is a right end of the power piston 6 and an insertion hole 8 provided in the front shell 2. An output shaft whose left end projects and outputs leftward toward a master cylinder (not shown) when the power piston 6 moves to the left. Reference numeral 9 indicates a front seal that seals between the output shaft 7 and the insertion hole 8 of the front shell 2. The reference numeral 10 indicates that the left end 10a is in contact with the inner wall portion 11 of the front shell 2 and the right end 10b is in contact with the left end surface portion 12 of the power piston 6. A return spring for urging the power piston 6 to the right with a predetermined urging force. Reference numeral 13 is a diaphragm having a bead-shaped inner peripheral portion 14 supported by the power piston 6 and an outer peripheral portion 15 supported by the housing 5, respectively. Shows.

Then, the inside of the housing 5 is communicated from the negative pressure communication pipe 16 to a negative pressure source (not shown) by the diaphragm 13 and a negative pressure chamber 17 on the front shell 2 side which is always in a negative pressure state, and a not shown not shown. It is partitioned into an operating pressure chamber 19 on the side of the rear shell 4 into which the atmosphere is introduced or discharged according to the operation of the operating rod 18 which moves in the left-right direction by the operation of the brake pedal.

The power piston 6 is disposed in the housing 5 by being provided in a cylindrical portion 20 which is formed so as to project from the rear shell 4 and extends in the left-right direction, and which is provided on the left side of the cylindrical portion 20. A generally bottomed cylindrical valve body portion 23 having a flange portion 21 having a diameter larger than the tubular portion 20 by a predetermined amount and for controlling the introduction / exhaust of atmospheric air in the working pressure chamber 19. And a piston portion 24 that extends outward from the outer peripheral portion of the collar portion 21 of the valve body portion 23 and receives the differential pressure between the negative pressure chamber 17 and the working pressure chamber 19.

Further, the rear shell 4 is provided with a cylindrical large-diameter protruding portion 4a protruding rightward and a small-diameter protruding portion 4b on the right side of the large-diameter protruding portion 4a, which is smaller in diameter than the large-diameter protruding portion 4a. The tubular portion 20 of the valve body portion 23 is slidably fitted and supported in the fitting insertion hole 25a of the substantially cylindrical rear seal / support member 25 supported on the inner peripheral side of the small-diameter protruding portion 4b. There is. The working pressure chamber 19 is constituted by being surrounded by the rear shell 4, the diaphragm 13, the valve body portion 23, the rear seal / support member 25, and the like.

The inner peripheral portion of the tubular portion 20 of the valve body portion 23 has a large-diameter inner peripheral portion 30 having a predetermined diameter provided from its right end portion to a predetermined position, and a left-hand side of the large-diameter inner peripheral portion 30. It has a small-diameter inner peripheral portion 31 that is smaller in diameter than the large-diameter inner peripheral portion 30 by a predetermined amount, and a bottom portion 32 on the left side of the small-diameter inner peripheral portion 31. A step portion 33 is formed in the circumferential direction along the direction orthogonal to the axis of the valve body portion 23 at the boundary with the circumferential portion 31.

Further, in the vicinity of the bottom portion 32 of the left end portion of the small-diameter inner peripheral portion 31 of the valve body portion 23, an opening is formed in the vicinity of the bottom portion 32 and penetrates through the valve body portion 23 to communicate with the negative pressure chamber 17. A series of through holes 34 are provided, and further, a valve plunger chamber 35 having a diameter smaller than that of the small diameter inner peripheral portion 31 by a predetermined amount is provided in the bottom portion 32 inside the first series through holes 34. As a result, the bottom portion 32 near the boundary between the valve plunger chamber 35 and the small-diameter inner peripheral portion 31 is provided with the first seat surface (in the valve body portion) along the direction orthogonal to the axial direction of the valve body portion 23. Sheet surface 36 is formed.

A valve plunger 38 is slidably inserted into the valve plunger chamber 35 of the valve body portion 23. On the other hand, the valve body portion 23 is provided with a second communication hole 39 in a direction perpendicular to the axis of the valve body portion 23 from the valve plunger chamber 35. It is in communication with the dynamic pressure chamber 19. Further, on the left side of the valve plunger 38 of the valve body portion 23, a right end 41 of the output shaft 7 is provided in a state where a reaction disk 40 which is a pressure deformable member is held.

Here, the valve plunger 38 is provided with a groove portion 43 at a predetermined position on the outer peripheral portion, and on the right side thereof, an operating rod connecting hole 45 to which the spherical portion 44 of the operating rod 18 is connected. Is provided. A seat portion 47 extending rightward by a predetermined length is provided outside the operating rod connecting hole 45, and the right end portion of the seat portion 47 is provided on the second seat surface (the valve plunger). Sheet surface 48).

The operating rod 18 has a first shaft portion 49 having a predetermined diameter on the right side and a first shaft portion 49 provided at a predetermined position on the left side of the first shaft portion 49 with a predetermined width. A fixed-diameter large-diameter collar portion 50, a second shaft portion 51 provided on the left side of the collar-shaped portion 50 for a predetermined length and having substantially the same diameter as the first shaft portion 49, and a left side of the second shaft portion 51. A third shaft portion 52 having a predetermined diameter smaller than that of the second shaft portion 51 and having a tapered shape, and the spherical portion 44 provided on the left side of the third shaft portion 52. ing. Then, one end of a first spring 53, which will be described later, is provided at a boundary portion between the collar portion 50 and the second shaft portion 51, and a second spring, which will be described later, is provided at a boundary portion between the second shaft portion 51 and the third shaft portion 52. One ends of 54 are in contact with each other.

A plate 56 is inserted into the second communication hole 39 of the valve body portion 23 with a gap of a predetermined width, and an upper end portion of the plate 56 has a gap of a predetermined width in the groove portion 43 of the valve plunger 38. Has been inserted with. Further, the lower end portion thereof can come into contact with a stopper 57 mounted in the rear shell 4 so that the movement thereof beyond a predetermined position in the right direction is restricted. The plate 56 regulates the limit position of the right movement of the power piston 6 and the positional relationship between the power piston 6 and the valve plunger 38.

A retainer 58, a poppet valve 59, a first spring 53, a second spring 54, etc. are provided between the valve body portion 23 and the operating rod 18. Next, these will be described. The valve mechanism 22 described above includes the poppet valve 59 and the first seat surface 36 and the second seat surface 48 described above.

The retainer 58 has a diameter substantially equal to that of the large-diameter inner peripheral portion 30 of the valve body portion 23 provided on one end side thereof, and is along a predetermined axial direction (left-right direction in the drawing) of the valve body portion 23. A first tubular portion 60 having a length, a first perforated disc portion 61 extending radially inward from the left end of the first tubular portion 60, and an axis line from the inside of the first perforated disc portion 61. A second tubular portion 62 extending a predetermined length to the left in the direction and having a smaller diameter than the large-diameter inner peripheral portion 30 by a predetermined amount, and a second perforated portion extending radially inward from the left end of the second tubular portion 62. It is an integrally molded product having a disc portion 63.

A portion of the retainer 58 surrounded by the first perforated disc portion 61, the second cylindrical portion 62, the large-diameter inner peripheral portion 30 of the valve body portion 23, and the step portion 33 has a poppet valve 59. An outer peripheral bead portion 64 is fitted in, and the outer peripheral bead portion 64 blocks communication between the outer peripheral side of the retainer 58 and the inner peripheral side of the valve body portion 23.

Further, between the boundary portion between the second cylindrical portion 62 and the second perforated disc portion 63 of the retainer 58 and the boundary portion between the collar-shaped portion 50 of the operating rod 18 and the second shaft portion 51. A first spring 53 having a predetermined biasing force is provided. The operating rod 18 is biased to the right by the first spring 53, and the second seat surface 48 of the valve plunger 38 to which the operating rod 18 is connected is biased by the biasing force or the like to the first position of the poppet valve 59. It is designed to sit on the three-seat surface 65.

In the poppet valve 59, the outer peripheral bead portion 64, and the third seat surface 65 that can be seated on and separated from the first seat surface 36 of the valve body portion 23 and the second seat surface 48 of the valve plunger 38 are located on the left side. It has a valve portion 66 provided and a rolling portion 67 which is expandable and contractable for connecting the valve portion 66 and the outer peripheral bead portion 64. A reinforcing disc 68 is fixed to the right surface of the valve portion 66. ing.

A second spring 54 having a predetermined biasing force is provided between the disc 68 and the boundary portion between the second shaft portion 51 and the third shaft portion 52 of the operating rod 18. The second spring 54 urges the third seat surface 65 of the poppet valve 59 to be seated on the first seat surface 36 of the valve body portion 23 and the second seat surface 48 of the valve plunger 38.

Here, the third seat surface 65 of the poppet valve 59 is seated on and off the first seat surface 36 of the valve body portion 23, whereby the working pressure chamber 19 and the negative pressure chamber 17 are communicated / blocked with each other. The third seat surface 65 is seated on and off the second seat surface 48 of the valve plunger 38, so that the working pressure chamber 19 and the atmosphere are communicated and shut off. The valve composed of the third seat surface 65 and the first seat surface 36 is called a vacuum valve, and the valve composed of the third seat surface 65 and the second seat surface 48 is called an atmospheric valve. ..

In the vicinity of the opening of the valve body portion 23, there is a cylindrical portion 70 which is inserted into the large-diameter inner peripheral portion 30 of the valve body portion 23 with a predetermined interval, and a left end portion of the cylindrical portion 70. The inner abutting portion 71 that projects a predetermined amount radially outward from the valve body 23 and abuts the large-diameter inner circumferential portion 30, and the inner side abutting portion 71 of the cylindrical portion 70 that is radially inward from the right end portion opposite to the inner abutting portion 71. Integrally formed with a locking portion 72a that extends a predetermined amount, and an outer contact portion 72b that extends radially outward from the same position as the locking portion 72a and contacts the right end portion of the valve body portion 23. A locking retainer 73 is provided. Here, the inner contact portion 71 causes the locking retainer 73 to dispose the cylindrical portion 70 at a position substantially coaxial with the valve body portion 23. The locking portions 72a are formed by cutting and raising a part of the cylindrical portion 70, and a plurality of locking portions 72a are provided in the circumferential direction.

The space between the cylindrical portion 70 of the locking retainer 73 and the operating rod 18 constitutes an atmosphere introducing passage 74, and the atmosphere introducing passage 74 has a flange shape of the operating rod 18. An atmosphere passage member 75 is provided at a position in contact with the portion 50 in a state of being fixed to the locking retainer 73. The atmosphere passage member 75 is composed of at least one of a filter member that prevents dust and the like in the atmosphere from entering the valve body portion 23 and a silencer member that suppresses the generation of sound when the atmosphere is introduced. The filter member is made of sponge or the like that is coarse enough to remove dust in the atmosphere, and the silencer member is compression molded with finer mesh than the filter member. It is made of felt.

Further, one end side of a boot 76 that prevents dust and the like from adhering between the valve body 23 and the rear seal / support member 25 is locked to the locking portion 72 a of the locking retainer 73. The boot 76 is an integrally molded product made of an elastic material, and has an inner engagement portion 77 that engages with the locking portion 72a, and extends radially outward from the right end portion of the inner engagement portion 77. And the expandable bellows portion 78b extending leftward from the radially outer end of the perforated disc portion 78a, and the small diameter of the rear shell 4 provided at the left end portion of the bellows portion 78b. It is composed of an outer engaging portion 79 that engages with the outer peripheral portion of the protruding portion 4b. The perforated disk portion 78a of the boot 76 is in contact with the locking portion 72a and the outer contact portion 72b of the locking retainer 73, and the perforated disk portion 78a and the bellows portion 78b are the valve body. An outer space portion 80 is formed between the outer peripheral portion of the portion 23.

At the right end of the valve body 23, a notch 81 is provided at a predetermined position that does not open to the working pressure chamber 19 when the power piston 6 moves leftward. This notch 81 Of the valve body portion 23 and the first atmosphere passage member 75 form a communication passage that communicates the inner space portion 82 with the outer space portion 80.

According to the pneumatic booster 1 of the first embodiment having the configuration described above, in the normal state (the state where the brake pedal is not depressed, etc.), the poppet valve 59 urges the second spring 54. The third seat surface 65 and the first seat surface 36 and the second seat surface 48 are brought into contact with each other to close the vacuum valve and the atmosphere valve, and the first series communication hole of the working pressure chamber 19 and the negative pressure chamber 17 is formed. 34, the valve plunger chamber 35 and the second communication hole 39 are cut off from each other, and the working pressure chamber 19 and the atmosphere are cut off from each other via the valve plunger chamber 35 and the second communication hole 39.

When the brake pedal is stepped on and the valve plunger 38 is moved leftward with respect to the valve body portion 23 via the operating rod 18, the second seat surface 48 of the valve plunger 38 and the third seat surface of the poppet valve 59. 65 is separated from the atmospheric pressure valve to open the atmospheric pressure valve, and the atmospheric pressure is introduced into the working pressure chamber 19 through the valve plunger chamber 35 and the second communication hole 39 to cause a difference between the working pressure chamber 19 and the negative pressure chamber 17. A pressure is generated, and the power piston 6 is moved leftward so as to cause the output shaft 7 to project due to this differential pressure, and a boosting operation is performed. Here, at the initial stage of the boosting operation of introducing the atmosphere, the valve mechanism 22 in the valve body portion 23 and the atmosphere have already passed through the atmosphere passing member 75 (that is, the intake resistance by the atmosphere passing member 75 is not received). In addition to the atmosphere stored in the inner space portion 82 between the passage member 75 and the outer space portion between the boot 76 and the outer peripheral portion of the valve body portion 23, which has also passed through the atmosphere passage member 75. The atmosphere stored in 80 and the atmosphere stored in the cutout portion 81 for communicating the inner space portion 82 and the outer space portion 80 are introduced into the working pressure chamber 19. Therefore, the atmosphere that has passed through the atmosphere passing member 75 is sufficiently stored, and this atmosphere is introduced into the working pressure chamber 19 at the initial stage of the boosting operation, so that the power piston 6 is immediately actuated. There is no delay in the rise of the output of the pneumatic booster 1. Therefore, the responsiveness is excellent. Moreover, since the volume of the outer space portion 80 is reduced by the movement of the valve body portion 23, the atmosphere in this portion is compressed and the atmosphere is easily supplied to the working pressure chamber 19.

Next, a pneumatic booster according to a second embodiment of the present invention will be described below with reference to FIG. The pneumatic booster of the second embodiment mainly differs from the pneumatic booster of the first embodiment in that a communication passage is provided in the valve body portion 23 instead of the notch. Therefore, the same parts are denoted by the same reference numerals, and different parts will be mainly described below.

In the second embodiment, a fixed position on the right end side of the valve body portion 23 passes through the tubular portion 20 from a predetermined position on the inner peripheral portion on the left side of the atmosphere passage member 75 of the valve body portion 23. A communication passage 83 is provided to be drawn out to the outer peripheral portion (a position where the power piston 6 does not open to the working pressure chamber 19 when the power piston 6 moves to the left), and a lock is provided at the right end portion of the valve body portion 23. A retainer 84 is provided. The locking retainer 84 is tapered and has a left end portion that extends radially inward, and a predetermined amount radially outward from the left end portion of the taper tubular portion 85. An engaging portion 86 that abuts and engages with the large-diameter inner peripheral portion 30 of the outlet valve body portion 23, and extends radially outward from the right end portion of the tapered cylindrical portion 85 and abuts the right end portion of the valve body portion 23. The contact portion 87 is provided. Here, in the boot 76, the inner diameter of the perforated disk portion 78a is larger than that of the above-described first embodiment due to the shape of the locking retainer 84. The inner peripheral portion of the valve body portion 23 constitutes the atmosphere introduction passage 74 as it is, and the atmosphere passage member 75 is fitted in the atmosphere introduction passage 74. The locking portion 86 is formed by cutting and raising a part of the tapered cylindrical portion 85, and a plurality of locking portions 86 are provided in the circumferential direction.

According to the pneumatic booster of the second embodiment having such a configuration, the effect of what has been described in the first embodiment, that is, at the beginning of the boosting operation for introducing the atmosphere, the atmospheric pressure booster is already activated. In addition to the atmosphere stored in the inner space 90 between the valve mechanism 22 and the atmosphere passage member 75 in the valve body portion 23 that has already passed through the member 75, it also passes through the atmosphere passage member 75. The atmosphere stored in the outer space portion 80 between the boot 76 and the outer peripheral portion of the valve body portion 23 is stored in the communication passage 83 that connects the inner space portion 90 and the outer space portion 80. The atmospheric pressure is introduced into the working pressure chamber 19, so that the power piston 6 is immediately actuated and the output of the pneumatic booster 1 is not delayed, and the response is excellent. It is not good to have the effect of becoming In addition, since the opening area of the atmosphere introduction passage 74 is increased, the intake resistance due to the atmosphere passage member 75 provided in the atmosphere introduction passage 74 is reduced, and the good response is achieved in all boost operation. Will be obtained.

In the first and second embodiments described above, the pneumatic booster for assisting the brake operation is described as an example, but the pneumatic booster for assisting the clutch depression can also be applied. Of course it is possible.

[0036]

[Effect of the device]

 As described above in detail, according to the pneumatic booster of the present invention, at the initial stage of the boosting operation for introducing the atmosphere, it has already passed through the atmosphere passing member (that is, the intake resistance due to the atmosphere passing member is received. In addition to the atmosphere stored in the inner space between the valve mechanism in the valve body and the atmosphere passage member, the boot and the outer periphery of the valve body that have also passed through the atmosphere passage member Since the atmosphere stored in the outer space between the space and the atmosphere stored in the communication passage that connects the inner space and the outer space are introduced into the working pressure chamber, The piston operates immediately and there is no delay in the rise of the output of the pneumatic booster. Therefore, the response is excellent.

[Brief description of drawings]

FIG. 1 is a cross-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 cross-sectional view showing a conventional pneumatic booster,
It shows a non-operating state.

[Explanation of symbols]

 1 Atmospheric pressure booster 5 Housing 6 Power piston 7 Output shaft 13 Diaphragm 17 Negative pressure chamber 18 Operating rod 19 Operating pressure chamber 22 Valve mechanism 23 Valve body part 74 Atmosphere introduction passage 75 Atmosphere passage member 76 Boot 80 Outside space 81 Notch Part (Communication passage) 82 Internal space 83 Communication passage

Claims (1)

[Scope of utility model registration request] 1. A power piston, which is slidably supported by a valve body portion in a housing, and has an atmosphere introducing passage for introducing atmosphere to the inner peripheral side of the valve body portion, and the power piston. A diaphragm that partitions the inside of the housing into a negative pressure chamber that communicates with a negative pressure source and an operating pressure chamber that selectively communicates with the negative pressure chamber or the atmosphere, and a diaphragm provided on the inner peripheral side of the valve body portion. A valve mechanism for controlling communication between the working pressure chamber and the negative pressure chamber and communication between the working pressure chamber and the atmosphere, an operating rod for operating the valve mechanism, the negative pressure chamber and the working pressure chamber The output shaft that is output by the power piston that moves due to the differential pressure and the outer peripheral portion of the valve body portion that projects from the housing while providing an outer space portion between the outer peripheral portion and the outer peripheral portion. At the same time, a boot that expands and contracts according to the sliding of the valve body portion is provided, and the atmosphere introduction passage is provided with an atmosphere passage member including at least one of a filter member and a silencer member. In the force device, a pneumatic booster is provided, which is provided with a communication passage that connects the outer space portion and an inner space portion between the valve mechanism in the valve body portion and the atmosphere passage member.