JP2005212550A - Negative pressure type booster - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a negative pressure type booster having good responsiveness at sudden operation and performing silent operation during normal operation, capable of providing an air purifying function anytime and avoiding contamination due to air of a structural member existing at a portion from a purifying filter to a pressure changing chamber. <P>SOLUTION: The negative pressure type booster has the purifying filter 80 provided on an air introduction passage Po for introducing the air to an atmospheric valve seat 41a, for purifying the air, and a muffling filter 90 made of material having a density higher than that of the purifying filter 80 and arranged at an upstream side of the purifying filter 80, while having a housing 10, a movable partition wall 20, a power piston 30, an input member 40, an output member 50, and a control valve 70. An opening/closing valve V for closing when advancing quantity with regard to the power piston 30 of the input member 40 is a prescribed value or less and for opening when the advancing quantity is larger than the prescribed value, is interposed in a bypass passage P1 bypassing the muffling filter 90 to introduce the air. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a negative pressure booster, and more particularly to a negative pressure booster including a purifying filter for purifying the atmosphere and a muffler filter for obtaining a quiet operation.

  A negative pressure booster is generally a movable partition that divides the housing into a constant pressure chamber and a variable pressure chamber, a power piston coupled to the movable partition, and can move forward and backward relative to the power piston in the power piston. The variable pressure chamber and the atmosphere are communicated with each other by an input member that is installed at the outside and receives an operating force from the outside, an output member that outputs the driving force of the power piston to the outside, and an atmospheric valve seat provided on the input member. A negative pressure control valve portion for controlling communication / cutoff between the variable pressure chamber and the constant pressure chamber by an atmospheric control valve portion for controlling shutoff and a negative pressure valve seat provided on the power piston is assembled in the power piston. It has an attached control valve.

In the negative pressure type booster described above, a purification filter that is provided in an atmosphere introduction path for introducing the atmosphere into the atmosphere valve seat and purifies the atmosphere, and is composed of a material having a higher density than the purification filter, and the purification filter Is provided with a muffler filter disposed upstream of the first, for example, described in Patent Document 1 below.
Japanese Patent Laid-Open No. 10-167044

Further, in the negative pressure booster described above, a purification filter that is provided in an atmosphere introduction path for introducing the atmosphere into the atmosphere valve seat and purifies the atmosphere, and penetrates the purification filter in the front-rear direction (axial direction). There is a thing provided with the sleeve which opens and closes the air passage formed in the inside by a part of the above-mentioned input member, for example, is indicated in the following patent documents 2.
Japanese National Patent Publication No. 11-505194

  In the negative pressure booster described in Patent Document 1 described above, the atmosphere is introduced into the atmosphere valve seat through the silencer filter and the purification filter at any operation. For this reason, in any operation, a silent operation can be obtained by the muffler filter, and an air purification function can be obtained by the purification filter. However, since the atmosphere is introduced into the atmosphere valve seat through the muffler filter and the purification filter, there is a limit to reducing the ventilation resistance when the atmosphere is introduced into the atmosphere valve seat, and the operation responsiveness at the time of sudden operation is reduced. It may not be able to be raised sufficiently.

  On the other hand, in the negative pressure type booster described in Patent Document 2 described above, during normal operation, the air passage in the sleeve is closed by a part of the input member, and the atmosphere passes through the purification filter to the atmosphere valve seat. Although introduced, the air passage in the sleeve is not closed by a part of the input member and opened during a sudden operation, and the atmosphere is introduced into the atmosphere valve seat without passing through the purification filter. For this reason, the air purification function is obtained by the purification filter during normal operation. Also, during sudden operation, air is introduced into the air valve seat through the air passage in the sleeve, so that the airflow resistance when air is introduced into the air valve seat can be sufficiently reduced, and its operating response The sex can be enhanced sufficiently. However, at the time of sudden operation, the purification function of the air by the purification filter cannot be obtained, and there is a possibility that the constituent members in the region from the purification filter to the variable pressure chamber are contaminated by the unpurified air. Moreover, in this negative pressure type booster, there is no description about the muffler filter, and there is a possibility that a quiet operation cannot be obtained.

  The present invention has been made in view of the above-described actual circumstances, and has good responsiveness during sudden operation, quiet operation during normal operation, and an air purification function that can be obtained at any time from a purification filter. An object of the present invention is to provide a negative pressure booster capable of avoiding contamination by air of constituent members located in a region reaching a transformer room.

  In order to achieve such an object, according to the present invention, a movable partition that divides the inside of the housing into a constant pressure chamber and a variable pressure chamber, a power piston coupled to the movable partition, and a front and rear of the power piston in the power piston. The variable pressure chamber and the atmosphere are provided by an input member that is installed to be able to travel and that receives an operating force from the outside, an output member that outputs the propulsive force of the power piston to the outside, and an atmospheric valve seat provided on the input member. The power piston has a negative pressure control valve unit that controls communication / blocking between the variable pressure chamber and the constant pressure chamber by an atmospheric control valve unit that controls communication / blocking and a negative pressure valve seat provided in the power piston. And a control filter for purifying the atmosphere provided in an atmosphere introduction path for introducing the atmosphere into the atmosphere valve seat, and a material having a higher density than the purification filter. In a negative pressure booster comprising a silencer filter that is configured and disposed upstream of the purification filter, a bypass passage that bypasses the silencer filter and can introduce the atmosphere is provided, and the power of the input member An on-off valve is provided in the bypass passage that closes when the advance amount relative to the piston is less than a predetermined value and opens when the advance amount is greater than the predetermined value.

  In this negative pressure type booster, when the advance amount of the input member relative to the power piston is larger than a predetermined value, that is, when the valve is suddenly operated, the open / close valve interposed in the bypass passage opens, so the atmosphere bypasses the silencing filter and bypasses the bypass passage. Through, the air is introduced into the atmospheric valve seat through a purification filter provided in the atmospheric air introduction path. For this reason, at the time of sudden operation, it is possible to eliminate the ventilation resistance due to the silencer filter, and to sufficiently reduce the ventilation resistance when the atmosphere is introduced into the atmospheric valve seat, and to sufficiently increase the operation responsiveness. it can. Further, at this time, the function of purifying air by the purification filter is obtained, and it is possible to avoid the contamination of the constituent members in the region from the purification filter to the variable pressure chamber by the atmosphere.

  Further, in this negative pressure type booster, when the advance amount of the input member relative to the power piston is less than a predetermined value, that is, during normal operation, the open / close valve interposed in the bypass passage is closed without opening, so that the atmosphere is silenced. It is introduced into the atmospheric valve seat through a filter and a purification filter provided in the atmospheric introduction path. For this reason, at the time of normal operation, the muffler filter functions effectively and a quiet operation can be obtained. Further, at this time, the function of purifying air by the purification filter is obtained, and it is possible to avoid the contamination of the constituent members in the region from the purification filter to the variable pressure chamber by the atmosphere.

  In implementing the present invention, both the purification filter and the muffler filter may be formed in an annular shape, and the muffler filter may have a larger diameter than the purification filter. In this case, it is possible to obtain a silencing effect equivalent to that of a small diameter silencing filter with a large diameter silencing filter with a large passage area and small passage resistance, and improve the operation responsiveness during normal operation. Is possible. In this case, the muffler filter may be disposed coaxially on the outer periphery of the purification filter. In this case, the dimension in the front-rear direction can be reduced, and the negative pressure booster can be reduced in the front-rear direction.

  In carrying out the present invention, the purification filter is disposed in the rear cylinder portion of the power piston, and the muffler filter is disposed in the front end portion of the cylindrical boot that covers the rear cylinder portion of the power piston from the outside. Then, air is introduced into the silencer filter through an air intake hole provided in the cylindrical boot, and the second filter formed between the silencer filter and the purification filter is formed between the rear cylinder portion of the power piston and the cylindrical boot. It is also possible to introduce the atmosphere through the atmosphere introduction path. In this case, the muffler filter can be disposed in front of the purification filter and at a position far from the operator of the negative pressure booster, thereby reducing the influence of atmospheric suction sound on the operator during normal operation. Thus, it is possible to improve the operation feeling.

  Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show an embodiment of a negative pressure booster according to the present invention. The negative pressure booster includes a movable partition wall 20 and a power piston 30 assembled to a housing 10, and power. An input member 40, an output member 50, a control valve 70, etc., a purification filter 80, a muffler filter 90, and the like that are assembled to the piston 30 are provided.

  As shown in FIG. 1, the housing 10 includes a front shell 11 and a rear shell 12, and a negative pressure source (for example, an intake manifold of an engine (not shown)) is internally passed through a negative pressure introduction pipe 13 by a movable partition wall 20. Are constantly divided into a constant pressure chamber R1 and a variable pressure chamber R2 which communicates with and shuts off the constant pressure chamber R1 and the atmosphere. The housing 10 has a stationary member, that is, a screw member provided at a rear end portion of a plurality of tie rods 14 (one is shown in FIG. 1) penetrating the housing 10 and the movable partition wall 20 in an airtight manner. It is configured to be fixed to a vehicle body (not shown). Note that a brake master cylinder 100 is assembled to a thread portion provided at the front end portion of the tie rod 14.

  The movable partition wall 20 includes a metal plate 21 and a rubber diaphragm 22, and is installed to be movable in the front-rear direction (the axial direction of the power piston 30) with respect to the housing 10. The diaphragm 22 is airtightly sandwiched between the folded portion provided on the outer peripheral edge of the rear shell 12 and the front shell 11 at a bead portion formed on the outer peripheral edge thereof. The diaphragm 22 is airtightly fixed together with the plate 21 in a groove provided on the outer periphery of the front flange portion of the power piston 30 at a bead portion formed on the inner peripheral edge thereof.

  The brake master cylinder 100 shown in FIG. 1 has a rear end portion 101a of the cylinder body 101 penetrating through a central cylindrical portion formed in the front shell 11 and airtightly entering the constant pressure chamber R1. The rear surface of the flange portion 101 b formed in contact with the front surface of the front shell 11. Further, the piston 102 of the brake master cylinder 100 protrudes rearward from the cylinder body 101 and enters the constant pressure chamber R1, and is configured to be pushed forward by the tip of the output member 50.

  The power piston 30 is a hollow piston coupled to the movable partition wall 20 and is assembled to the rear shell 12 of the housing 10 so as to be airtight and movable in the front-rear direction at a portion formed in a cylindrical shape. A spring 31 interposed between the housing 10 and the front shell 11 is urged rearward. As shown in FIG. 2, the power piston 30 has a reaction force chamber hole 30a, a contact member housing hole 30b having a smaller diameter than the reaction force chamber hole 30a, a plunger from the front end surface toward the rear end surface. A storage hole 30c, a plunger / control valve storage hole 30d having a diameter larger than that of the plunger storage hole 30c, a purification filter storage hole 30e, and the like are sequentially provided. The contact member storage hole 30b is continuous with the reaction force chamber hole 30a. Concentrically, an annular groove 30f is provided.

  The power piston 30 is provided with a key member insertion hole 30g corresponding to the plunger accommodation hole 30c in the radial direction, and a communication hole 30h capable of communicating the constant pressure chamber R1 and the plunger / control valve accommodation hole 30d. In addition, an annular negative pressure valve seat 30i on which an annular negative pressure control valve portion 70a of the control valve 70 can be seated is formed at the rear end portion of the communication hole 30h. Further, the power piston 30 is provided with a communication hole 30j through which the inner peripheral side of the annular negative pressure valve seat 30i can communicate with the variable pressure chamber R2.

  The input member 40 is a member that is installed in the power piston 30 so as to be able to move forward and backward with respect to the power piston 30 and receives an operating force from the outside, and is connected to the plunger / control valve from the contact member housing hole 30b of the power piston 30. A plunger 41 accommodated in the accommodation hole 30d and movable in the front-rear direction (axial direction) with respect to the power piston 30, and connected to the plunger 41 in a joint shape at a spherical tip 42a and braked at a rear end 42b An input rod 42 connected to the pedal 110 (see FIG. 1) is provided.

  As shown in FIG. 2, the plunger 41 is opposed to the power piston 30 via a contact member 61 that is assembled to the contact member housing hole 30 b of the power piston 30 so as to be movable in the front-rear direction. An annular atmospheric valve seat 41a that can be engaged with the reaction force member 62 accommodated in the force chamber hole 30a and is detachably seated on the annular atmospheric control valve portion 70b of the control valve 70 is formed at its rear end. ing. The reaction force member 62 is a reaction rubber disk, and comes into contact with the reaction force receiving surface of the power piston 30 while being accommodated in the cylindrical portion 51 a of the rear member 51 of the output member 50, and the front surface of the contact member 61. Can be contacted.

  The output member 50 is integrated with a reaction member 62 and a rear member 51 which is assembled to the reaction force chamber hole 30a and the annular groove 30f of the power piston 30 so as to be movable in the front-rear direction, and a front end portion of the rear member 51. The front end of the output rod 52 abuts against the engaging portion of the piston 102 in the brake master cylinder 100 so as to be slidable.

  The key member 63 is inserted into a radial key member insertion hole 30 g formed in the power piston 30 in order to regulate the movement of the plunger 41 in the front-rear direction with respect to the power piston 30. The thickness dimension of the key member 63 in the front-rear direction is smaller than the dimension in the front-rear direction of the key member insertion hole 30g, and the key member 63 is movable in the front-rear direction by a predetermined amount with respect to the power piston 30. The key member 63 can be brought into contact with the rear shell 12 at the rear end surfaces of both end portions projecting radially outward from the power piston 30, and the rearward movement limit position of the power piston 30 relative to the housing 10 is shown in FIG. As shown, the front wall of the key member insertion hole 30g is in contact with the front end surface of the key member 63, and the rear end surfaces of both ends of the key member 63 are in contact with the rear shell 12.

  Further, the key member 63 can be brought into contact with the front and rear end surfaces of the annular groove 41b formed in the central portion of the plunger 41 at the central portion thereof, and the movement limit position of the plunger 41 to the rear with respect to the power piston 30 is The front end surface of the annular groove 41b is in contact with the front end surface of the key member 63, and the rear end surface of the key member 61 is in contact with the rear wall of the key member insertion hole 30g. The forward movement limit position of the plunger 41 with respect to the power piston 30 is such that the rear end surface of the annular groove 41b abuts on the rear end surface of the key member 63 and the front end surface of the key member 63 is on the front wall of the key member insertion hole 30g. This is the abutting position.

  The control valve 70 includes a cylindrical movable portion 70A having the annular negative pressure control valve portion 70a and the annular atmospheric control valve portion 70b described above, and a step portion formed in the plunger / control valve storage hole 30d of the power piston 30. A cylindrical fixed portion 70B fitted and fixed in an airtight manner, and a cylindrical bellows portion 70D that connects the cylindrical movable portion 70A and the cylindrical fixed portion 70B. The cylindrical movable part 70A is urged forward by a spring 71 interposed between the cylindrical fixed parts 70B, and is movable in the front-rear direction. The cylindrical fixing portion 70 </ b> B is urged forward by a spring 72 interposed between the input rods 42 and is fixed to the power piston 30. The rear end of the spring 72 is engaged with the input rod 42 via a spring retainer 73.

  The negative pressure control valve portion 70a can be seated and separated from an annular negative pressure valve seat 30i formed on the power piston 30, and the communication between the constant pressure chamber R1 and the variable pressure chamber R2 is blocked by the seating on the negative pressure valve seat 30i. The constant pressure chamber R1 and the variable pressure chamber R2 are communicated by separating from the negative pressure valve seat 30i. The atmospheric control valve portion 70b can be seated and separated from an annular atmospheric valve seat 41a formed on the plunger 41, and the communication between the variable pressure chamber R2 and the atmosphere is blocked by the seating on the annular atmospheric valve seat 41a. The atmosphere from the atmospheric pressure valve seat 41a is communicated with the variable pressure chamber R2.

  The purification filter 80 is a low-density foam material that is provided in the atmosphere introduction path Po (passage formed between the power piston 30 and the input rod 42) for introducing the atmosphere into the atmosphere valve seat 41a and purifies the atmosphere. It is formed in an annular shape and is interposed between the input rods 42 in the filter accommodation hole 30 e of the power piston 30. The purifying filter 80 is held at the inner periphery of the front end by the above-described spring retainer 73, held at the front outer periphery by the holder 81, and held at the rear end by the valve plate 82.

  The holder 81 has a cylindrical portion 81a and an annular flange portion 81b, is fitted and fixed to the filter housing hole 30e of the power piston 30 at the outer periphery of the cylindrical portion 81a, and is purified at the inner periphery of the cylindrical portion 81a. It is installed on the front outer periphery of 80. The annular flange portion 81b has a larger diameter than the outer periphery of the rear end portion of the power piston 30, and extends and contracts the cylindrical boot 32 that covers and protects the sliding portion of the power piston 30 with respect to the housing 10, that is, the rear cylinder portion from the outside. A ventilation hole 81b1 is provided for ease.

  The valve plate 82 is formed in a circular shape that is annular and convex rearward, has a cylindrical portion 82a on the inner periphery, and is disposed at the rear end of the purification filter 80 in the front. The valve plate 82 is assembled to the outer periphery of the nut 83 at the cylindrical portion 82 a so as to be airtight and slidable in the front-rear direction, and is urged rearward by a spring 84 interposed between the nuts 83. ing.

  The nut 83 is assembled to the outer periphery of the threaded portion 42c of the input rod 42 so that the position can be adjusted in the front-rear direction, and has an annular protrusion 83a that can come into contact with the rear end of the tubular portion 82a of the valve plate 82. . A spring retainer 85 with which the front end of the spring 84 abuts is assembled on the outer periphery of the front end portion of the nut 83.

  The muffler filter 90 is disposed on the upstream side (atmosphere side) of the purification filter 80 and is made of a material having a higher density than the purification filter 80 (for example, wool felt), and has a larger diameter than the purification filter 80. Is formed. The muffler filter 90 is coaxially arranged on the outer periphery of the rear portion of the purification filter 80, the front end portion is held by the annular flange portion 81 b of the holder 81 described above, and the outer periphery and the rear end portion are held by the cover 91. Yes.

  The cover 91 has a plurality of air intake holes 91a in the outer peripheral portion that accommodates the muffler filter 90, and has an inner peripheral portion formed in a spherical shape that is annular and concave forward, and a valve plate 82 (annular and rearward). Is formed in a convex spherical shape), thereby bypassing the silencing filter 90 and forming a bypass passage P1 through which air can be introduced. An annular atmospheric control valve body 92 is airtightly assembled to the inner peripheral end of the cover 91. The cover 91 and the valve plate 82 are held in the illustrated state by the elastic holding force at the rear end of the cylindrical boot 32.

  The annular atmospheric control valve element 92 constitutes an on-off valve V with a valve plate 82, a spring 84, and the like. The on-off valve V is interposed in the bypass passage P1, and when the advance amount of the input member 40 such as the input rod 42 and the nut 83 relative to the power piston 30 is less than a predetermined value so as to be obtained in the normal operation. Is closed as shown in FIG. 3, and is set to open as shown in FIG. 4 when the advance amount is larger than a predetermined value, as obtained in the operation at the time of sudden operation. Since the cover 91 and the valve plate 82 are both formed in a spherical shape, the function of the on-off valve V can be obtained without change even when the input rod 42 is swung in an arc.

  In the negative pressure type booster of this embodiment configured as described above, the input member 40 is moved relative to the power piston 30 when the brake pedal 110 is depressed and the input rod 42 is pushed forward. By moving forward, the negative pressure control valve portion 70a is seated on the negative pressure valve seat 30i, the communication between the constant pressure chamber R1 and the variable pressure chamber R2 is interrupted, and the atmospheric valve seat 41a is separated from the atmospheric control valve portion 70b. Thus, the variable pressure chamber R2 communicates with the air introduction path Po. Therefore, at this time, the atmosphere introduced into the atmosphere introduction path Po is supplied to the variable pressure chamber R2, and the movable partition wall 20, the power piston 30 and the like are pushed forward.

  By the way, at the time of the brake operation described above, as shown in FIG. 3, the on-off valve V interposed in the bypass passage P1 does not open during the normal operation in which the advance amount of the input member 40 relative to the power piston 30 is a predetermined value or less. Therefore, the atmosphere is introduced from the intake hole 91a of the cover 91 into the atmosphere valve seat 41a through the silencing filter 90 and the purification filter 80 provided in the atmosphere introduction path Po. For this reason, at the time of normal operation, the silence filter 90 functions effectively and a quiet operation can be obtained. Further, at this time, the function of purifying air by the purification filter 80 is obtained, and it is possible to avoid contamination of the constituent members in the region from the purification filter 80 to the variable pressure chamber R2 by the atmosphere.

  Further, when the brake is actuated as described above, the opening / closing valve V interposed in the bypass passage P1 opens as shown in FIG. 4 when the advancement amount of the input member 40 relative to the power piston 30 is larger than a predetermined value. The atmosphere bypasses the silencing filter 90, passes through the bypass passage P1, and is introduced into the atmosphere valve seat 41a through the purification filter 80 provided in the atmosphere introduction path Po. For this reason, at the time of sudden operation, it is possible to eliminate the ventilation resistance due to the muffler filter 90 and to sufficiently reduce the ventilation resistance when the atmosphere is introduced into the atmosphere valve seat 41a, and to sufficiently enhance the operation responsiveness. be able to. Also at this time, the function of purifying the air by the purification filter 80 is obtained, and it is possible to avoid contamination of the constituent members in the region from the purification filter 80 to the variable pressure chamber R2 by the atmosphere.

  When the brake operation is completed and the brake pedal 110 is returned, the input member 40 moves backward with respect to the power piston 30 so that the negative pressure control valve portion 70a is separated from the negative pressure valve seat 30i. The constant pressure chamber R1 and the variable pressure chamber R2 communicate with each other, and the atmospheric valve seat 41a is seated on the atmospheric control valve portion 70b, so that the communication between the variable pressure chamber R2 and the atmospheric introduction path Po is blocked. Therefore, at this time, the air supplied to the variable pressure chamber R2 is guided to the negative pressure source through the constant pressure chamber R1 and the negative pressure introduction pipe 13 and the like, and the movable partition wall 20, the power piston 30 and the like are pushed back by the spring 31. 2 to return to the state of FIG.

  When the brake pedal 110 is rapidly returned during the return operation, the purification filter 80 and the atmospheric control valve body 92 (mainly the purification filter 80) are bent as shown in FIG. Compared to 30, the vehicle moves backward significantly compared to the normal return operation. Therefore, at this time, the negative pressure control valve portion 70a is largely separated from the negative pressure valve seat 30i, and the return is completed at an early stage as compared with the normal return operation.

  In the negative pressure booster of this embodiment, both the purification filter 80 and the silencing filter 90 are formed in an annular shape, and the silencing filter 90 has a larger diameter than the purification filter 80. For this reason, it is possible to obtain a silencing effect equivalent to that of a small diameter silencing filter with a large diameter silencing filter 90 with a large passage area and small passage resistance, and it is possible to improve the operation responsiveness during normal operation. It is. Moreover, in this embodiment, since the muffler filter 90 is coaxially disposed on the outer periphery of the purification filter 80, the front-rear dimension can be reduced, and the negative pressure booster can be reduced in the front-rear direction. Is possible.

  In the above-described embodiment, as shown in FIG. 2, the silencer filter 90 is coaxially arranged on the outer periphery of the rear portion of the purification filter 80. However, as shown in FIG. It is also possible to carry out by arranging coaxially with the purification filter 80 in the front end portion of the boot 32. In this embodiment, the atmosphere is introduced into the muffler filter 90 through the intake hole 32 a provided in the cylindrical boot 32, and the second filter formed between the power piston 30 and the cylindrical boot 32 from the muffler filter 90 to the purification filter 80. The atmosphere is introduced through the atmosphere introduction path P2.

  In the embodiment shown in FIG. 6, an annular and thin atmospheric control valve element 92 is airtightly assembled to the valve plate 82. An annular leaf spring 84 is employed as the spring 84 that biases the valve plate 82 rearward. Other configurations are the same as the configuration of the embodiment shown in FIG.

  In the embodiment of FIG. 6 described above, the muffler filter 90 can be disposed in front of the purification filter 80 at a location far from the operator of the negative pressure booster, that is, the driver. For this reason, it is possible to reduce the influence of the atmospheric suction sound on the driver during normal operation and improve the operation feeling. In this embodiment, it is possible to make the rear part of the negative pressure booster compact.

  In each of the above-described embodiments, the present invention is applied to a single-type negative pressure booster. However, the present invention can be similarly applied to a tandem or triple-type negative pressure booster. In addition, the present invention can be implemented with appropriate modifications within the scope of the claims.

It is sectional drawing which shows one Embodiment of the negative pressure type booster by this invention. It is a principal part expanded sectional view of FIG. FIG. 3 is an operation explanatory diagram of the portion shown in FIG. 2 during normal operation. FIG. 3 is an operation explanatory diagram of the portion shown in FIG. 2 during a sudden operation. FIG. 3 is an operation explanatory diagram of the part shown in FIG. 2 during rapid return. It is sectional drawing equivalent to FIG. 2 which shows other embodiment of the negative pressure type booster by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Housing, 20 ... Movable partition, 30 ... Power piston, 30i ... Negative pressure valve seat, 40 ... Input member, 41 ... Plunger, 41a ... Atmospheric valve seat, 50 ... Output member, 70 ... Control valve, 70a ... Negative pressure control Valve part, 70b ... Air control valve part, 80 ... Purification filter, 90 ... Silencer filter, R1 ... Constant pressure chamber, R2 ... Transformer room, Po ... Air introduction passage, P1 ... Bypass passage, P2 ... Second air introduction passage, V ... Open / close valve

Claims (4)

A movable partition that divides the inside of the housing into a constant pressure chamber and a variable pressure chamber, a power piston coupled to the movable partition, and a power piston that is installed in the power piston so as to be able to move forward and backward, and to operate from the outside An input member for receiving the power, an output member for outputting the propulsive force of the power piston to the outside, and an atmospheric control valve unit for controlling communication / blocking between the variable pressure chamber and the atmosphere by an atmospheric valve seat provided on the input member; A negative pressure valve seat provided in the power piston and a negative pressure control valve portion for controlling communication / blocking between the variable pressure chamber and the constant pressure chamber, and a control valve assembled in the power piston. A purification filter that is provided in an atmosphere introduction path for introducing the atmosphere into the atmosphere valve seat and purifies the atmosphere, and is composed of a material having a higher density than the purification filter and is disposed upstream of the purification filter. In the vacuum booster which is equipped with a silencer filter to be location,
An on-off valve that bypasses the muffler filter and that can introduce air, and that closes when the advance amount of the input member relative to the power piston is less than a predetermined value and opens when the advance amount is greater than a predetermined value. A negative pressure booster interposed in the bypass passage.   2. The negative pressure booster according to claim 1, wherein both the purification filter and the muffler filter are formed in an annular shape, and the muffler filter has a larger diameter than the purification filter. Negative pressure type booster.   3. The negative pressure booster according to claim 2, wherein the muffler filter is coaxially disposed on the outer periphery of the purification filter. 3. The negative pressure booster according to claim 2, wherein the purification filter is disposed in a rear cylinder portion of the power piston, and the muffler filter is a front end of a cylindrical boot that covers the rear cylinder portion of the power piston from the outside. The air is introduced into the silencing filter through an air intake hole provided in the cylindrical boot, and from the silencing filter to the purification filter, between the rear cylindrical portion of the power piston and the cylindrical boot. A negative pressure booster characterized in that the atmosphere is introduced through the formed second atmosphere introduction path.

Images