JP5716541B2 - Negative pressure booster - Google Patents

Description

  The present invention relates to a negative pressure booster employed in a vehicle brake device.

  As one of the negative pressure type boosters of this type, a housing that forms a pressure chamber therein, a pressure chamber that is assembled in the housing so as to be capable of moving forward and backward, and a negative pressure chamber in the front and a rear variable pressure chamber, A movable partition that is partitioned into a housing, a valve piston that is assembled to the housing so as to be capable of moving forward and backward, and is coupled to the movable partition at a front end portion accommodated in the housing, and the valve piston in the valve piston An input member that can be moved forward and backward and receives an operating force from the outside, an output member that is assembled to the front end portion of the valve piston and outputs the driving force of the valve piston to the outside, and the valve piston And a reaction force member that is interposed between the input member and the output member and transmits a reaction force acting on the output member separately to the valve piston and the input member. In addition, the variable pressure chamber and the negative pressure valve seat provided in the valve piston and the negative pressure valve seat provided in the valve piston are controlled by an annular atmospheric valve portion provided in the input member to control communication / blocking between the variable pressure chamber and the atmosphere. A control valve having a negative pressure control valve portion for controlling communication / blocking with the pressure chamber and assembled in the valve piston, and assembled so as to be capable of moving forward and backward with respect to the input member and the valve piston. There exists a negative pressure type booster provided with the key member which prescribes | regulates the limit of the forward / backward movement with respect to the said valve piston of the said input member, for example, it describes in following patent document 1. FIG. Note that the rear means the brake pedal side or the vehicle rear side with respect to the negative pressure booster, and the front means the brake master cylinder side or the vehicle front side with respect to the negative pressure booster.

JP 2010-234958 A

  In the negative pressure type booster described in Patent Literature 1 described above, the atmospheric valve portion and the atmospheric air are formed between the input member and the valve piston in front of the atmospheric valve portion and the atmospheric control valve portion. Rectification that is formed in a shape that does not protrude outwardly from the outer diameter of the atmospheric valve portion in the air passage that guides air flowing in between the control valve portions to the variable pressure chamber, and is arranged in front of the atmospheric valve portion by a predetermined amount. Is provided. For this reason, when the air flows through the air passage by the rectification unit arranged in front of the atmospheric valve unit by a predetermined amount, generation of vortex in front of the atmospheric valve unit is suppressed, and a problem caused by eddy current (air Generation of intake noise in the passage) can be suppressed. In this negative pressure booster, the flow resistance in the air passage is formed because the rectifying portion provided in the air passage is formed in a shape that does not protrude outward from the outer diameter of the atmospheric valve portion. It is possible to suppress the increase in the operating pressure of the negative pressure type booster.

  However, in the negative pressure type booster described in Patent Document 1 described above, the rectification unit is disposed in front of the atmospheric valve unit by a predetermined amount. For this reason, there is a space where vortex flow is generated by the air guided to the variable pressure chamber between the rectifying unit and the atmospheric valve unit, and there is a limit to the effect of reducing the intake noise in the air passage, and further improvement is desired. It was.

The present invention has been made to meet the above-described demand, and is formed between the input member and the valve piston in front of the atmospheric valve portion and the atmospheric control valve portion in the negative pressure type booster. In the air passage for guiding the air flowing in between the atmospheric valve portion and the atmospheric control valve portion to the variable pressure chamber,
A cylindrical shape that is smaller in diameter than the outer diameter of the atmospheric valve portion, is formed coaxially with the valve piston, is disposed in front of the atmospheric valve portion by a predetermined amount, and supports a part of the input member so that the input member can be moved forward and backward. A support is provided,
It is arranged between this cylindrical support part and the atmospheric valve part, the front end part is assembled so as to be able to advance and retreat with respect to the outer periphery of the cylindrical support part, and has the same outer diameter as the outer diameter of the atmospheric valve part, A cylindrical rectification unit capable of moving forward and backward integrally with the atmospheric valve unit is provided continuously with respect to the atmospheric valve unit.

  In this negative pressure type booster, the above-described cylindrical support part and the cylindrical rectification part are provided in the above-described air passage, and between the atmospheric valve part and the cylindrical rectification part and between the cylindrical rectification part and the cylindrical support. It can be configured so that a space where vortex flow is not formed between the portions. For this reason, the air guided toward the variable pressure chamber through the space between the atmospheric valve portion and the atmospheric control valve portion is directed from the outer periphery of the atmospheric valve portion toward the outer periphery of the cylindrical support portion along the outer periphery of the cylindrical rectifying portion. It can be made to flow continuously without being generated. Therefore, it is possible to eliminate problems due to vortex flow in the air flowing from the outer periphery of the atmospheric valve portion toward the outer periphery of the cylindrical support portion (generation of intake noise in the air passage).

  Further, in this negative pressure type booster, the outer diameter of the rectifying portion provided in the air passage is substantially the same as the outer diameter of the atmospheric valve portion, and is formed in a shape that does not protrude outward from the atmospheric valve portion. Therefore, it is possible to suppress an increase in flow resistance in the air passage, and it is possible to favorably maintain the operation response of the negative pressure booster.

  In carrying out the present invention, an urging member that urges the cylindrical rectifying portion rearward may be provided between the cylindrical support portion and the cylindrical rectifying portion. In this case, the urging member can hold the rear end surface of the cylindrical rectification unit in contact with the front end surface of the atmospheric valve unit, and the rear end surface of the cylindrical rectification unit and the front end surface of the atmospheric valve unit It is possible to elastically maintain a state in which there is no gap (a vortex generation space) between them. In this case, the biasing member can also function as a return spring for the input member.

  In carrying out the present invention, it is also possible to form a tapered surface whose diameter decreases toward the front on the outer periphery of the front end portion of the cylindrical rectifying portion. In this case, it is possible to reduce (or eliminate) the step formed at the front end of the cylindrical rectification unit, and to suppress (or eliminate) the generation of vortex flow at the step. Yes, it is possible to reduce the generation of intake noise in the air passage.

It is a partial fracture side view showing one embodiment of a negative pressure type booster by the present invention. It is a principal part expanded sectional view of the negative pressure type booster shown in FIG. FIG. 5 is an enlarged cross-sectional view of a main part corresponding to FIG. 2 showing another embodiment of the negative pressure booster according to the present invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The negative pressure type booster shown in FIGS. 1 and 2 includes a movable partition wall 20 and a valve piston 30 assembled to the housing 10, and is opposed to an input member 40 and an output member 50 assembled to the valve piston 30. A force member 60, a control valve 70, a key member 80, and the like are provided.

  As shown in FIG. 1, the housing 10 includes a front shell 11 and a rear shell 12 that form a pressure chamber Ro therein, and the internal pressure chamber Ro is negatively pressured through a negative pressure introducing pipe 13 by a movable partition wall 20. It is divided into a front negative pressure chamber R1 that always communicates with a source (for example, an intake manifold of an engine not shown), and a rear pressure chamber R2 that communicates with and shuts off the negative pressure chamber R1 and the atmosphere. The housing 10 includes a plurality of bolts 14 (one is shown in FIG. 1) penetrating the rear shell 12 in an airtight manner and nuts (not shown) screwed on the bolts 14. (Not shown). Further, in front of the housing 10, a plurality of bolts 15 (one is shown in FIG. 1) penetrating the front shell 11 in an airtight manner and nuts 16 screwed to the bolts 15 are used for braking. A master cylinder 100 is assembled. Note that the bolt 14 and the bolt 15 may be configured by a single bolt (a bolt that hermetically penetrates the movable partition wall 20 at the intermediate portion).

  The movable partition wall 20 includes a metal plate 21 and a rubber diaphragm 22 and is assembled in the housing 10 so as to be capable of moving forward and backward. 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 valve piston 30 at a bead portion formed on the inner peripheral edge thereof.

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

  The valve piston 30 is a hollow piston coupled to the movable partition 20 at the front end portion accommodated in the housing 10, and is airtight to the rear shell 12 of the housing 10 at a portion formed in a cylindrical shape. Further, it is assembled so as to be able to advance and retreat, and is urged rearward by a spring 31 interposed between the housing 10 and the front shell 11. As shown in FIG. 2, the valve piston 30 has a reaction force chamber hole 30a, a plunger tip storage hole 30b having a smaller diameter than the reaction force hole 30a, a plunger from the front end surface toward the rear end surface. The housing hole 30c, the plunger housing hole 30d having a diameter larger than that of the plunger housing hole 30c, the control valve housing hole 30e, the filter housing hole 30f, and the like are provided with a shaft hole penetrating in the front-rear direction.

  Further, the valve piston 30 is provided with a key member insertion hole 30g in the radial direction corresponding to the plunger housing hole 30c. Further, the valve piston 30 is provided with a pair of communication holes 30h (one is not shown) capable of communicating the negative pressure chamber R1 and the control valve housing hole 30e, and the rear end of each of these communication holes 30h. An arcuate negative pressure valve seat 30i is formed on which the negative pressure control valve portion 70a of the control valve 70 can be seated. The valve piston 30 has a housing hole 30j for housing the shaft center portion of the key member 80, a cylindrical axial communication hole 30k for communicating the housing hole 30j and the plunger housing hole 30d, and a housing hole 30j and a shaft. A radial communication hole 30m that allows the direction communication hole 30k to communicate with the variable pressure chamber R2 is formed.

  The input member 40 is a member that is installed in the valve piston 30 so as to be able to advance and retreat with respect to the valve piston 30 and receives an operating force (input) from the outside, and is controlled from the plunger tip portion accommodation hole 30b of the valve piston 30. A plunger 41 accommodated in the valve accommodation hole 30e and movable in the axial direction (front-rear direction) with respect to the valve piston 30, and a rear end portion 42b (see FIG. 1), an input rod 42 connected to a brake pedal (not shown) and a tip member 43 assembled between the plunger 41 and the reaction member 60 are provided. The distal end member 43 is accommodated in the plunger distal end accommodating hole 30b of the valve piston 30 so as to be able to move forward and backward. The front end member 43 can be brought into contact with the reaction force member 60 at the front end surface, and the front end surface of the plunger 41 at the rear end surface. It can be engaged and disengaged (can contact).

  As shown in FIG. 2, the plunger 41 is assembled to the small diameter portion of the plunger tip housing hole 30b of the valve piston 30 at the tip so as to be slidable in the axial direction. The plunger housing hole 30c is assembled so as to be slidable in the axial direction, and is guided and supported by the valve piston 30. The plunger 41 can be engaged with the reaction force member 60 accommodated in the reaction force chamber hole 30a of the valve piston 30 via the tip member 43 at the tip (front end surface), and the control valve 70 is disposed at the rear end. An annular atmospheric valve seat 41a is formed on the atmospheric control valve portion 70b.

  The output member 50 outputs the driving force of the valve piston 30 to the outside, and the rear member 51 assembled to the reaction force chamber hole 30a of the valve piston 30 together with the reaction force member 60 so as to be movable in the axial direction. This is constituted by an output rod 52 that is integrally assembled to the distal end portion of the rear member 51. As shown in FIG. 1, the tip of the output rod 52 abuts against the engaging portion of the piston 102 in the brake master cylinder 100 so as to be able to be pushed.

  The reaction force member 60 is a reaction rubber disc interposed between the input member 40 and the output member 50 in the valve piston 30, and abuts against the rear end surface of the rear member 51 in the output member 50 at the front end surface thereof. At its rear end face, it abuts against the annular reaction force receiving surface 30n of the valve piston 30 and can abut against the front end face of the tip member 43, and the reaction force of the force acting on the output member 50 is The input member 40 (tip member 43) can be transmitted separately.

  The control valve 70 is hermetically fitted and fixed to the annular movable portion 70A having the negative pressure control valve portion 70a and the atmospheric control valve portion 70b described above, and the step portion formed in the control valve housing hole 30e of the valve piston 30. The annular fixed portion 70B is formed, and the cylindrical movable portion 70D that connects the annular movable portion 70A and the annular fixed portion 70B. The annular movable portion 70A is biased forward by a spring S1 interposed between the annular portions 42c provided on the input rod 42, and is movable in the front-rear direction. The annular fixing portion 70 </ b> B is fixed to the valve piston 30 by an annular retainer 71.

  The retainer 71 is assembled to the valve piston 30 and is fixed to the inner hole step portion of the valve piston 30, and the fixing portion 70 </ b> B of the control valve 70 is fixed to the valve piston 30. The retainer 71 is cut and raised and fixed to the valve piston 30 by a plurality of locking portions 71a.

  The negative pressure control valve portion 70a can be seated on and separated from a pair of arcuate negative pressure valve seats 30i formed on the valve piston 30, and the negative pressure chamber R1 and the variable pressure chamber R2 can be seated on the arcuate negative pressure valve seat 30i. And the negative pressure chamber R1 and the variable pressure chamber R2 are communicated with each other by separating from the arc-shaped negative pressure valve seat 30i. The atmospheric control valve part (valve seat) 70b can be seated / separated with respect to the annular atmospheric valve part 41a formed on the plunger 41, and the variable pressure chamber R2 communicates with the atmosphere by being seated on the annular atmospheric valve seat 41a. And the variable pressure chamber R2 communicates with the atmosphere by being separated from the annular atmosphere valve portion 41a.

  The key member 80 is for defining the limit of the axial movement (forward and backward movement) of the plunger 41 with respect to the valve piston 30 and for defining the backward position of the valve piston 30 with respect to the housing 10. It is assembled so as to be able to move forward and backward with respect to 30, and is inserted into a radial key member insertion hole 30 g formed in the valve piston 30. The thickness dimension of the key member 80 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 80 is movable in the front-rear direction by a predetermined amount with respect to the valve piston 30.

  The key member 80 can be in contact with the rear shell 12 at the rear end surfaces of both ends projecting radially outward from the valve piston 30, and the movement limit position (retreat position) of the valve piston 30 to the rear with respect to the housing 10. 2, the front wall of the key member insertion hole 30g is in contact with the front end surface of the key member 80, and the rear end surfaces of both ends of the key member 80 are in contact with the rear shell 12.

  Further, the key member 80 can contact the front and rear end faces 41b and 41c of the annular groove formed in the central portion of the plunger 41 at the central portion, and the plunger 41 is assembled to the valve piston 30. Later, it is assembled to the valve piston 30. The rearward movement limit position of the plunger 41 with respect to the valve piston 30 is such that the front end surface 41b of the annular groove contacts the front end surface of the key member 80 and the rear end surface of the key member 80 contacts the rear wall of the key member insertion hole 30g. Is the position. Further, the forward movement limit position of the plunger 41 with respect to the valve piston 30 is such that the rear end surface 41c of the annular groove is in contact with the rear end surface of the key member 80, and the front end surface of the key member 80 is on the front wall of the key member insertion hole 30g. This is the abutting position.

  The filter 91 is mounted between the input rods 42 in the filter housing hole 30f of the valve piston 30, and the filter 91 has a vent hole formed in a boot 92 that protects the sliding portion of the valve piston 30 from the outer periphery. Air (air) can flow in through 92a. The boot 92 is fitted and fixed to the rear end cylinder portion of the rear shell 12 in the housing 10 at the front end portion, and is fitted and fixed to the outer periphery of the intermediate portion of the input rod 42 at the rear end portion.

  In the negative pressure booster of this embodiment configured as described above, the variable pressure chamber R2 is disconnected from the negative pressure chamber R1 as the input member 40 moves forward relative to the valve piston 30 during a brake operation. The valve piston 30 moves forward by air (atmosphere) communicating with the atmosphere and flowing into the variable pressure chamber R2. At this time, the reaction force from the reaction force member 60 is transmitted to the valve piston 30 and the plunger 41 of the input member 40. When the brake is released after the brake operation described above, as the input member 40 moves backward with respect to the valve piston 30, the variable pressure chamber R2 is disconnected from the atmosphere and connected to the negative pressure chamber R1, and the variable pressure chamber R2 Due to the negative pressure, the valve piston 30 is moved backward by the spring 31. Thereby, each member returns to the original position shown in FIG. 2 and prepares for the next braking operation.

  By the way, in the negative pressure type booster of this embodiment, the cylindrical support portion 30p is provided in the air passage Pa that guides the air (atmosphere) flowing in between the atmospheric valve portion 41a and the atmospheric control valve portion 70b to the variable pressure chamber R2. In addition, a cylindrical rectification unit 44 is provided, and a biasing member (spring) 45 that urges the cylindrical rectification unit 44 rearward is provided between the cylindrical support unit 30p and the cylindrical rectification unit 44. Is provided. The air passage Pa is formed between the input member 40 and the valve piston 30 (specifically, the plunger accommodating hole 30d) in front of the atmospheric valve portion 41a and the atmospheric control valve portion 70b.

  The cylindrical support portion 30p has an outer diameter smaller than that of the atmospheric valve portion 41a, and is formed coaxially and integrally with the valve piston 30. Further, the cylindrical support portion 30p is disposed in front of the atmospheric valve portion 41a by a predetermined amount, and a part of the input member 40 (intermediate portion of the plunger 41) can be moved forward and backward on the inner periphery (plunger housing hole 30c). I support it.

  The cylindrical rectification part 44 is comprised by the member different from the plunger 41, and is arrange | positioned coaxially between the cylindrical support part 30p and the atmospheric valve part 41a. Further, the cylindrical rectifying portion 44 is assembled such that the front end portion thereof can be moved forward and backward with respect to the outer periphery of the cylindrical support portion 30p, the outer diameter thereof is substantially the same as the outer diameter of the atmospheric valve portion 41a, and the atmospheric valve portion 41a. The air valve portion 41a is continuously provided with no gap in the axial direction. Further, a tapered surface 44 a that is reduced in diameter toward the front is formed on the outer periphery of the front end portion of the cylindrical rectifying unit 44.

  For this reason, in the negative pressure type booster of this embodiment, the above-described cylindrical support part 30p and the cylindrical rectifying part 44 are provided in the above-described air passage Pa, and the atmospheric valve part 41a and the cylindrical rectifying part are provided. It is possible to configure so that a space in which vortex flows are not formed between 44 and between the cylindrical rectifying portion 44 and the cylindrical support portion 30p. For this reason, air (atmosphere) guided toward the variable pressure chamber R2 through the space between the atmospheric valve portion 41a and the atmospheric control valve portion 70b flows from the outer periphery of the atmospheric valve portion 41a along the outer periphery of the cylindrical rectifying portion 44. It can be made to flow continuously toward the outer periphery of 30p without generating a vortex. Therefore, it is possible to eliminate problems due to eddy currents in the air flowing from the outer periphery of the atmospheric valve portion 41a toward the outer periphery of the cylindrical support portion 30p (generation of intake noise in the air passage Pa).

  Moreover, in this negative pressure type booster, the outer diameter of the rectifying part 44 provided in the air passage Pa is substantially the same as the outer diameter of the atmospheric valve part 41a, and projects outward from the atmospheric valve part 41a. Since it is formed in a shape that does not, it is possible to suppress an increase in flow resistance in the air passage Pa, and it is possible to favorably maintain the operation response of the negative pressure booster.

  Further, in the negative pressure booster of this embodiment, a biasing member 45 that biases the cylindrical rectifying portion 44 rearward is provided between the cylindrical support portion 30p and the cylindrical rectifying portion 44. . For this reason, the urging member 45 can hold the rear end surface of the cylindrical rectifying portion 44 in contact with the front end surface of the atmospheric valve portion 41a, and the rear end surface of the cylindrical rectifying portion 44 and the atmospheric valve portion 41a. It is possible to elastically maintain a state in which there is no gap (a vortex generation space) between the front end surfaces. Further, the biasing member 45 can function as a return spring of the input member 40.

  Further, in this embodiment, a tapered surface 44 a that decreases in diameter toward the front is formed on the outer periphery of the front end portion of the cylindrical rectifying unit 44. For this reason, the step part formed in the front end of the cylindrical rectification | straightening part 44 can be made small (or eliminated), and generation | occurrence | production of the vortex | eddy_current in the same step part can be suppressed (or eliminated). Also by this, it is possible to reduce the generation of intake noise in the air passage Pa.

  In the above-described embodiment, the cylindrical rectifying unit 44 and the biasing member 45 are assembled between the cylindrical support unit 30p and the atmospheric valve unit 41a, but as in the other embodiments shown in FIG. It is also possible to implement by assembling only the cylindrical rectification unit 44 between the cylindrical support unit 30p and the atmospheric valve unit 41a. The cylindrical rectifying unit 44 shown in FIG. 3 is press-fitted into the plunger 41 and fixed integrally therewith, but a cylindrical rectifying unit corresponding to this is integrally formed with the plunger 41 for implementation. Is also possible.

  In the other embodiment shown in FIG. 3, a retainer 72 is assembled to the outer peripheral step portion of the input rod 42 instead of the annular portion 42 c of the input rod 42, and the retainer 72 and the control valve 70 are interposed between the retainer 72 and the control valve 70. A spring S1 is interposed. A spring S <b> 2 is interposed between the retainer 71 and the retainer 72. The spring S2 is a return spring that is interposed between the valve piston 30 and the input member 40 and urges the input member 40 backward toward a predetermined position with respect to the valve piston 30 via a retainer 71 at the front end. It engages with the valve piston 30 and engages with the input rod 42 of the input member 40 via the retainer 72 at the rear end.

  In the embodiment of FIG. 3 described above, the longitudinal length of the cylindrical rectifying unit 44 can be made shorter than that of the above-described embodiment, and the length of the air passage Pa is set to the above-described embodiment. The flow resistance in the air passage Pa can be reduced, and the operation responsiveness of the negative pressure booster can be improved.

  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.

DESCRIPTION OF SYMBOLS 10 ... Housing, 20 ... Movable partition, 30 ... Valve piston, 30i ... Negative pressure valve seat, 30p ... Cylindrical support part, 40 ... Input member, 41 ... Plunger, 41a ... Atmospheric valve part, 44 ... Rectification part, 44a ... Taper 45, biasing member, 50 ... output member, 60 ... reaction force member, 70 ... control valve, 70a ... negative pressure control valve portion, 70b ... atmospheric control valve portion, 80 ... key member, Ro ... pressure chamber, R1 ... Negative pressure chamber, R2 ... Transformer chamber, Pa ... Air passage

Claims (3)

A housing that forms a pressure chamber therein, a movable partition that is assembled in the housing so as to be capable of moving forward and backward, and divides the pressure chamber into a front negative pressure chamber and a rear variable pressure chamber, and can be moved forward and backward in the housing. And a valve piston coupled to the movable partition at the front end portion accommodated in the housing, and installed in the valve piston so as to be able to move forward and backward with respect to the valve piston and operated from the outside. An input member that receives force, an output member that is assembled to the front end portion of the valve piston and outputs the driving force of the valve piston to the outside, and is interposed between the input member and the output member in the valve piston And a reaction force member that transmits a reaction force of the force acting on the output member separately to the valve piston and the input member, and an annular member provided on the input member Communication / blocking between the variable pressure chamber and the negative pressure chamber is controlled by an atmospheric control valve unit that controls communication / blocking between the variable pressure chamber and the atmosphere by the atmospheric valve unit and a negative pressure valve seat provided on the valve piston. A control valve having a negative pressure control valve portion and assembled in the valve piston, and the input member and the valve piston are assembled so as to be capable of moving forward and backward, and the input member moves forward and backward with respect to the valve piston. In a negative pressure type booster with a key member that defines the limit of movement,
An air passage formed between the input member and the valve piston in front of the atmospheric valve portion and the atmospheric control valve portion and introducing air flowing between the atmospheric valve portion and the atmospheric control valve portion to the variable pressure chamber. ,
A cylindrical shape that is smaller in diameter than the outer diameter of the atmospheric valve portion, is formed coaxially with the valve piston, is disposed in front of the atmospheric valve portion by a predetermined amount, and supports a part of the input member so that the input member can be moved forward and backward. A support is provided,
It is arranged between this cylindrical support part and the atmospheric valve part, the front end part is assembled so as to be able to advance and retreat with respect to the outer periphery of the cylindrical support part, and has the same outer diameter as the outer diameter of the atmospheric valve part, A negative pressure booster characterized in that a cylindrical rectification unit capable of moving forward and backward integrally with the atmospheric valve unit is provided continuously with respect to the atmospheric valve unit. In the negative pressure type booster according to claim 1,
An urging member for urging the cylindrical rectifying portion rearward is provided between the cylindrical support portion and the cylindrical rectifying portion. In the negative pressure type booster according to claim 1 or 2,
A negative pressure type booster characterized in that a taper surface that decreases in diameter toward the front is formed on the outer periphery of the front end portion of the cylindrical rectifying unit.

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