JP2007022435A - Negative pressure type booster - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a negative pressure type booster assuring excellent response in actuation and an excellent calmness. <P>SOLUTION: The negative pressure type booster is equipped with a plunger 32 arranged to advance and retreat relative to a valve body 22 in the axial hole 22a of the valve body 22 coupled with a movable bulkhead 21 partitioning inside a housing 10 into a negative pressure chamber R1 and a pressure change chamber R2, a valve mechanism V furnished with a negative pressure valve to put the negative pressure chamber R1 in communication with the pressure change chamber R2 and shut the communication and with an atmospheric valve to put the pressure change chamber R2 in communication to the atmosphere and shut the communication, a reaction member 34 whose rear face admits engagement of the front extremities of the plunger 32 and the valve body 22, and an output shaft 35 whose tail is engaged with the front face of the reaction member 34. The atmosphere flows into the pressure change chamber R2 through the axial communication paths A2 and A4 and the radial communication paths B2 and B4 provided in the valve body 22. In the front parts of the axial communication paths A2 and A4, curved slopes S2 and S4 are formed which bend and change the flowing direction of the atmosphere flowing toward the pressure change chamber R2 one by one toward the radial inner ends of the communication paths B2 and B4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a negative pressure booster applied to an automobile, and in particular, an input is caused by a differential pressure generated between a front negative pressure chamber and a rear transformer chamber defined by a movable partition wall in a housing. The present invention relates to a negative pressure booster configured to be increased and output.

As one of the negative pressure type boosters of this type, a valve body connected to a movable partition that divides the inside of a housing into a front negative pressure chamber and a rear variable pressure chamber is provided with a shaft hole. A plunger that can advance and retreat in the axial direction with respect to the valve body, a negative pressure valve that communicates and blocks between the negative pressure chamber and the variable pressure chamber in accordance with a forward and backward movement of the plunger with respect to the valve body, and the variable pressure chamber And a reaction mechanism in which a front end portion of the plunger and a front end portion of the valve body can be engaged with the rear surface, and a rear surface on the front surface of the reaction member. An output member that is engaged at an end and is movable in the axial direction with respect to the valve body is assembled, and the plunger moves forward in the axial direction with respect to the valve body. Then, the communication between the negative pressure chamber and the variable pressure chamber is cut off, the atmospheric valve is opened, and the variable pressure chamber and the atmosphere are communicated with each other through the axial communication path and the radial communication path provided in the valve body. There exists what was comprised so that air | atmosphere might flow in into the said transformation room, for example, it describes in the following patent document 1. FIG.
JP-A-9-290742

  In the negative pressure booster described in Patent Document 1 described above, the axial communication path and the radial communication path provided in the valve body intersect each other at a substantially right angle, and the atmosphere flowing through the axial communication path is After striking the inner wall of the valve body at the end of the axial communication path and changing the direction at a substantially right angle, it flows toward the variable pressure chamber through the radial communication path. For this reason, the air flowing through the axial communication path is unlikely to flow smoothly through the radial communication path, and the flow tends to be disturbed. Therefore, the operation response delay and the operation sound are likely to occur due to the disturbance of the air flow.

  Moreover, in the negative pressure type booster described in Patent Document 1 described above, the air flowing through the axial communication path at the portion where the valve seat of the negative pressure valve formed in an arc shape is provided is the negative pressure valve. After the air flow through the axial communication passage is merged at the end of the axial communication passage at a portion where the valve seat is not provided, the flow is directed toward the variable pressure chamber through the radial communication passage. For this reason, turbulence is likely to occur in the air flow even by the above-described merging.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a negative pressure booster that is excellent in operation response and silence. In order to achieve such an object, in the present invention, a valve body connected to a movable partition wall that divides the inside of a housing into a front negative pressure chamber and a rear variable pressure chamber has a shaft hole, and the shaft hole has a shaft hole. A plunger that can advance and retreat in the axial direction with respect to the valve body, a negative pressure valve that communicates and blocks between the negative pressure chamber and the variable pressure chamber according to a forward and backward movement of the plunger with respect to the valve body, and the variable pressure chamber; A valve mechanism having an atmospheric valve for communicating and blocking between the atmospheres is incorporated, a reaction member in which a front end portion of the plunger and a front end portion of the valve body can be engaged with a rear surface, and a rear end on the front surface of the reaction member And an output member that is movable in the axial direction with respect to the valve body, and the plunger moves forward in the axial direction with respect to the valve body. Is closed, the communication between the negative pressure chamber and the variable pressure chamber is blocked, the atmospheric valve is opened and the variable pressure chamber and the atmosphere are communicated, and the axial communication path and the radial communication path provided in the valve body In the negative pressure type booster configured so that the atmosphere flows into the variable pressure chamber through the flow direction of the air flowing toward the variable pressure chamber through the axial communication path at the front portion of the axial communication path. The present invention is characterized in that an inclined surface that is sequentially changed toward the radially inner end of the directional communication passage is provided on the inner wall surface of the valve body. In this case, the inclined surface directs the flow direction of the air flowing toward the variable pressure chamber through the axial communication path toward the radially inner end portion of the radial communication path at a front portion of the axial communication path. It is also possible to form a curved inclined surface that is bent and changed sequentially.

  In this negative pressure type booster, when the plunger is moved forward in the axial direction with respect to the valve body, the negative pressure valve is closed, the communication between the negative pressure chamber and the variable pressure chamber is shut off, and the atmospheric valve is opened to change the pressure. The room communicates with the atmosphere. For this reason, the atmosphere flows into the variable pressure chamber through the axial communication path and the radial communication path provided in the valve body, and the pressure in the variable pressure chamber gradually increases from negative pressure to atmospheric pressure, and the differential pressure between the negative pressure chamber and the variable pressure chamber. An output corresponding to is generated in the output member. Further, when output is generated in the output member, the reaction force is transmitted from the output member to the front surface of the reaction member and from the rear surface of the reaction member to the valve body and the plunger.

  By the way, in the negative pressure type booster of the present invention, the air flowing toward the variable pressure chamber through the axial communication passage is axially flowed by the inclined surface (or curved inclined surface) provided on the inner wall surface of the valve body. It is sequentially changed (or sequentially bent and changed) toward the radially inner end of the radial communication path at the front portion of the directional communication path. For this reason, the air flow from the axial communication passage to the radial communication passage becomes smooth, and the air flow is hardly disturbed. Therefore, it is possible to suppress the delay in the operation response and the generation of the operation sound due to the disturbance of the atmospheric flow, and it is possible to obtain a good operation response and a quiet operation.

  In carrying out the above-described present invention, a shunt wall that shunts the air flowing toward the variable pressure chamber through the axial communication passage in the circumferential direction at a front portion of the axial communication passage is inward from the inner wall of the valve body. It is also possible that the curved inclined surface is formed on the flow dividing wall. In addition, a guide wall that forms the axial communication path with the inner wall of the shaft hole of the valve body is provided in a fan shape on the valve body along the outer periphery of the plunger, and the curved inclined surface is formed on the guide wall. It is also possible.

  In carrying out the present invention, the flow dividing wall and the guide wall are alternately provided in the valve body in the circumferential direction, and the flow direction is changed by the curved inclined surface formed in the flow dividing wall. It is also possible to separately provide a radial communication path through which the atmosphere flows and a radial communication path through which the atmosphere whose flow direction is changed by the curved inclined surface formed in the guide wall. In this case, the atmosphere whose flow direction is changed by the curved inclined surface formed on the flow dividing wall and the atmosphere whose flow direction is changed by the curved inclined surface formed on the guide wall are separately provided. It flows into the variable pressure chamber through each radial communication path. Therefore, before the atmosphere whose flow direction has been changed by the curved inclined surface formed on the flow dividing wall and the air whose flow direction has been changed by the curved inclined surface formed on the guide wall flow into the radial communication path. It is possible to prevent the occurrence of turbulence associated with such merging.

  In carrying out the present invention, the valve seat of the negative pressure valve may be formed in the valve body in an arc shape along the outer periphery of the plunger. In this case, it is possible to sufficiently secure a passage through which air flows and to sufficiently improve the operation response. Further, the plunger can be supported by the valve body so as to be slidable in the axial direction at a front position and a rear position from a portion where the curved inclined surface is provided. In this case, since there is no plunger support part in the middle of the passage through which air flows as shown in Patent Document 1, the air flow is smooth and quiet, and the plunger can be stably supported.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 to 3 show an embodiment in which the present invention is implemented in a negative pressure booster for a vehicle brake. In the negative pressure booster of this embodiment, a movable partition 21 and a valve body 22 are provided in a housing 10. The housing 10 is partitioned by a movable partition wall 21 into a front negative pressure chamber R1 and a rear variable pressure chamber R2.

  As shown in FIG. 1, the housing 10 includes a front shell 11 and a rear shell 12, and a negative pressure for constantly communicating the negative pressure chamber R1 with a negative pressure source (for example, an intake manifold of an engine not shown). An introduction pipe 13 is provided. The housing 10 is a stationary member by a screw portion 14a provided at the 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 21 in an airtight manner. That is, it is configured to be fixed to a vehicle body (not shown). Note that the brake master cylinder 100 is assembled to the screw portion 14b provided at the front end portion of the tie rod 14.

  The brake master cylinder 100 has a rear end portion 101a of the cylinder body 101 penetrating through a central cylinder portion 11a formed in the front shell 11 and hermetically entering the negative pressure chamber R1, and is formed in the cylinder body 101. The rear surface of the flange portion 101 b is in contact with the front surface of the front shell 11. The piston 102 of the brake master cylinder 100 protrudes rearward from the cylinder body 101 and enters the negative pressure chamber R1, and is configured to be pushed forward by a distal end rod portion 35a of the output shaft 35 described later. Has been.

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

  The valve body 22 of the power piston 20 is a resin hollow body connected to the inner peripheral portion of the movable partition wall 21, and is airtight and front-rear to the rear shell 12 of the housing 10 at an intermediate portion formed in a cylindrical shape. It is assembled so as to be movable in the direction, and is urged rearward by a return spring 15 interposed between the housing 10 and the front shell 11. The portion of the valve body 22 that protrudes outside the housing 10 is covered and protected by a boot 19 having a plurality of vent holes 19a at the rear end.

  Further, as shown in FIGS. 2 and 3, the valve body 22 is formed with a stepped shaft hole 22a penetrating in the front-rear direction, and at the rear end of the intermediate step portion of the shaft hole 22a. A pair of communication holes 22b that communicate with the negative pressure chamber R1 at the front end and a pair of key attachment holes 22c that are substantially orthogonal to the front portion of the shaft hole 22a and allow the key member 39 to be inserted from the outer periphery are formed. ing.

  The input shaft 31, the plunger 32, and the transmission member 33 are coaxially assembled in the above-described shaft hole 22a, and the valve mechanism V and the filters 51 and 52 are coaxially assembled. In addition, a reaction member 34 and an output shaft (output member) 35 are coaxially assembled in front of the transmission member 33 in the shaft hole 22a.

  The input shaft 31 can move forward and backward with respect to the valve body 22, and is connected to the receiving connection portion 32c of the plunger 32 in a joint shape by a spherical tip portion 31a, and the yoke by a rear end screw portion 31b (see FIG. 1). It is connected to the brake pedal 110 via 111, and is configured to receive a pedal force acting on the brake pedal 110 forward as an input Fi.

  The plunger 32 can be engaged with the central portion of the rear surface of the reaction member 34 through the transmission member 33 at the tip end portion 32a, and can be engaged with the key member 39 with an annular flange portion 32b formed in the intermediate portion thereof. The tip 32a is a part that receives the reaction force of the output Fo from the reaction member 34 partially. An annular atmospheric valve seat 32d is formed at the rear end of the plunger 32 so as to be separable from the annular atmospheric valve portion 41b of the valve mechanism V, and the annular atmosphere of the atmospheric valve seat 32d and the valve mechanism V is formed. The valve portion 41b constitutes an atmospheric valve that communicates and blocks between the variable pressure chamber R2 and the atmosphere.

  The reaction member 34 is a reaction rubber disk whose rear surface has a central portion that can be bulged and deformed rearwardly. In an engaged (abutted) state, the valve body 22 is assembled to the front end portion. The reaction member 34 can be brought into contact with the front surface of the distal end portion 32a of the plunger 32 via the transmission member 33 at the rear surface thereof, and is in contact with the annular front end surface of the valve body 22.

  The output shaft 35 is assembled in the front end portion of the shaft hole 22a of the valve body 22 together with the reaction member 34 so as to be movable in the front-rear direction, and as shown in FIGS. 1 and 2, the distal end assembled to the distal end portion. The rod portion 35a abuts against the engaging portion of the piston 102 in the brake master cylinder 100 so as to be able to be pushed, and the reaction force received from the piston 102 of the brake master cylinder 100 is transmitted to the reaction member 34 during braking operation. ing.

  The key member 39 defines the function of defining the movement of the plunger 32 in the front-rear direction with respect to the valve body 22 of the power piston 20 and the limit position of the rearward movement of the power piston 20 with respect to the housing 10 (rear return position of the valve body 22). It has a function and is assembled so as to be movable relative to the valve body 22 and the plunger 32 in the axial direction of the power piston 20.

  The valve mechanism V includes an arc-shaped negative pressure valve seat 22d formed integrally at the rear end of each communication hole 22b in the valve body 22, and an annular atmospheric valve seat 32d formed integrally at the rear end of the plunger 32. And a cylindrical valve body 41 that is coaxially disposed with respect to the atmospheric valve seat 32d and is assembled to the valve body 22. The valve body 41 has a negative pressure valve portion 41a that constitutes a negative pressure valve that can be seated / separated with respect to the negative pressure valve seat 22d and that allows the negative pressure valve seat 22d to communicate and block the negative pressure chamber R1 and the variable pressure chamber R2. The atmospheric valve seat 32d has an annular atmospheric valve portion 41b that constitutes an atmospheric valve that can be seated and separated from the atmospheric valve seat 32d and that can communicate with and shut off the atmosphere from the variable pressure chamber R2 by the atmospheric valve seat 32d.

  The negative pressure valve portion 41a and the atmospheric valve portion 41b are formed integrally with a movable portion (a portion movable in the axial direction) of the valve body 41, and are directed toward the negative pressure valve seat 22d and the atmospheric valve seat 32d by the compression spring 42. Is energized (towards the front). The fixed portion (portion that cannot move in the axial direction) of the valve body 41 is urged forward by a compression spring 44 that is engaged with the stepped portion of the input shaft 31 via the retainer 43, so that the valve body 22 is held at a fixed position (step portion) of the shaft hole 22a.

  With the configuration of the valve mechanism V described above, the variable pressure chamber R2 can communicate with the negative pressure chamber R1 or the atmosphere in accordance with the movement of the input shaft 31 and the plunger 32 in the front-rear direction with respect to the valve body 22. That is, the input shaft 31 and the plunger 32 shown in FIGS. 1 and 2 move forward with respect to the valve body 22, the negative pressure valve portion 41a is seated on the negative pressure valve seat 22d, and the atmospheric valve seat 32d is the atmospheric valve portion. When separated from 41b, the variable pressure chamber R2 is disconnected from the negative pressure chamber R1 and communicates with the atmosphere. At this time, the ventilation hole 19a of the boot 19, the filters 51 and 52, the inside of the valve body 41, the gap between the atmospheric valve seat 32d and the atmospheric valve portion 41b, the axial communication paths A1 to A4 provided in the valve body 22 and the radial direction The air flows into the variable pressure chamber R2 through the communication paths B1 to B4.

  Further, as shown in FIGS. 1 and 2, the input shaft 31 and the plunger 32 return to the return position with respect to the valve body 22, and the negative pressure valve portion 41a is separated from the negative pressure valve seat 22d, and the atmospheric valve seat 32d. Is seated on the atmospheric valve portion 41b, the variable pressure chamber R2 is disconnected from the atmosphere and communicated with the negative pressure chamber R1. At this time, the negative pressure is supplied from the variable pressure chamber R2 through the radial communication passages B1 to B4 and the axial communication passages A1 to A4 provided in the valve body 22, the gap between the negative pressure valve portion 41a and the negative pressure valve seat 22d, the communication hole 22b, and the like. Air is sucked into the chamber R1.

  Each of the axial communication paths A1 and A2 described above is formed along the outer periphery of the plunger 32 at the inner periphery of each negative pressure valve seat 22d (rear end portion of the communication hole 22b), as shown in FIGS. This arc-shaped passage is formed in a bilaterally symmetric shape, and is provided with a branch wall 22e at each front portion thereof for diverting the air flowing toward the variable pressure chamber R2 in the circumferential direction. Each flow dividing wall 22e is provided so as to protrude inward from the inner wall of the valve body 22, and each of the axial communication paths A1 and A2 is divided into approximately equal halves. Surfaces S1 and S2 are formed, respectively.

  Each curved inclined surface S1 causes the flow direction of the air flowing toward the variable pressure chamber R2 through the upper half of FIG. 3 of each axial communication path A1, A2 to the front portion of the upper half of FIG. 3 of each axial communication path A1, A2. The radial communication passage B1 (passage formed in the upper half of FIG. 3 of the key attachment hole 22c) is sequentially bent and changed toward the radially inner end, and is formed at the front end of the flow dividing wall 22e. Yes. Each curved inclined surface S2 causes the flow direction of the air flowing toward the variable pressure chamber R2 through the lower half of each axial communication passage A1, A2 in FIG. 3 to the front portion of the lower half of FIG. 3 of each axial communication passage A1, A2. The radial communication path B2 (passage formed in the lower half of FIG. 3 of the key attachment hole 22c) is sequentially bent and changed toward the radially inner end, and is formed at the front end of the flow dividing wall 22e. Yes.

  On the other hand, each of the axial communication paths A3 and A4 described above is a fan-shaped path formed along the outer periphery of the plunger 32 at a portion where each negative pressure valve seat 22d is not provided, as shown in FIG. It is formed in a vertically symmetrical shape, and a rib 22f that bisects the air flowing toward the variable pressure chamber R2 in the circumferential direction is provided at a circumferential intermediate portion thereof, and a fan-like shape is provided at a front portion of the rib 22f. A guide wall 22g is provided. Each guide wall 22g extends to the inner wall of the shaft hole 22a of the valve body 22, and curved inclined surfaces S3 and S4 are formed on the right side surface in FIG.

  Each curved inclined surface S3 in the upper part of FIG. 3 has a radial communication path B3 (key) at the front part of the axial communication path A3 in the flow direction of the air flowing toward the variable pressure chamber R2 through the axial communication path A3 in the upper part of FIG. 3 is formed by continuously bending and changing toward the radially inner end of a passage formed separately from the passage formed in the upper half of FIG. 3 of the mounting hole 22c, and continuously formed at the front end of the rib 22f. It is formed in the front part of the guide wall 22g. Each curved inclined surface S4 in the lower part of FIG. 3 indicates the flow direction of the air flowing toward the variable pressure chamber R2 through the axial communication path A4 in the lower part of FIG. 3 at the front part of the axial communication path A4. In the radial direction inner end portion of a passage formed separately from the passage formed in the lower half of FIG. 3 of the mounting hole 22c, it is sequentially bent and changed, and is continuously formed at the front end portion of the rib 22f. It is formed in the front part of the guide wall 22g.

  In the negative pressure booster of the embodiment configured as described above, when the brake pedal 110 is depressed and the input shaft 31 and the plunger 32 are moved forward in the axial direction with respect to the valve body 22, the negative pressure valve portion 41a is By sitting on the negative pressure valve seat 22d, the negative pressure valve is closed, the communication between the negative pressure chamber R1 and the variable pressure chamber R2 is blocked, and the atmospheric valve seat 32d is separated from the atmospheric valve portion 41b, whereby the atmospheric valve is Open and communication between the variable pressure chamber R2 and the atmosphere is established. For this reason, the atmosphere flows into the variable pressure chamber R2 through the axial communication passages A1 to A4 and the radial communication passages B1 to B4 provided in the valve body 22, and the pressure in the variable pressure chamber R2 gradually becomes the atmospheric pressure from the negative pressure. An output Fo corresponding to the differential pressure between the negative pressure chamber R1 and the variable pressure chamber R2 is generated on the output shaft 35. Further, when the output Fo is generated in the output shaft 35, the reaction force is transmitted from the output shaft 35 to the front surface 34a of the reaction member 34, directly transmitted from the rear surface 34b of the reaction member 34 to the valve body 22, and the transmission member 33 is transmitted. To the plunger 32.

  By the way, in the negative pressure type booster of this embodiment, the air flowing toward the variable pressure chamber R2 through the axial communication paths A1 to A4 is caused by the curved inclined surfaces S1 to S4 provided on the inner wall surface of the valve body 22. The flow direction is changed by sequentially bending toward the radially inner end of each of the radial communication paths B1 to B4 at the front portion of each of the axial communication paths A1 to A4. For this reason, the air flow from the axial communication passages A1 to A4 to the radial communication passages B1 to B4 is smooth, and the air flow is less likely to be disturbed. Therefore, it is possible to suppress the delay in the operation response and the generation of the operation sound due to the disturbance of the atmospheric flow, and it is possible to obtain a good operation response and a quiet operation.

  Further, in the negative pressure booster of this embodiment, the air flowing toward the variable pressure chamber R2 through the axial communication passages A1 and A2 is diverted in the circumferential direction at the front portion of the axial communication passages A1 and A2. The flow dividing wall 22e is provided so as to protrude inward from the inner wall of the valve body 22, and curved curved surfaces S1 and S2 are formed on the flow dividing wall 22e. Further, a guide wall 22g for forming each axial communication path A3, A4 with the inner wall of the shaft hole 22a of the valve body 22 is provided in a fan shape on the valve body 22 along the outer periphery of the plunger 32, and the guide wall 22g Each curved inclined surface S3, S4 is formed in the front part.

  Moreover, in the negative pressure type booster of this embodiment, each flow dividing wall 22e and each guide wall 22g are alternately provided in the valve body 22 in the circumferential direction, and each formed in each flow dividing wall 22e. Air in which the flow direction has been changed by the respective radial communication paths B1, B2 through which the air whose flow direction has been changed by the curved inclined surfaces S1, S2 flows and the respective curved inclined surfaces S3, S3 formed in the respective guide walls 22g. The radial communication passages B3 and B4 through which the gas flows are provided separately. For this reason, the flow direction is changed by the air whose flow direction is changed by the curved inclined surfaces S1 and S2 formed on the flow dividing walls 22e and the curved inclined surfaces S3 and S4 formed on the guide walls 22g. The air thus formed flows into the variable pressure chamber R2 through the radial communication paths B1, B2 and B3, B4 provided separately. Accordingly, the flow direction is changed by the atmosphere whose flow direction is changed by the curved inclined surfaces S1 and S2 formed on the flow dividing walls 22e and the curved inclined surfaces S3 and S4 formed on the guide walls 22g. The air does not merge before flowing into the radial communication paths B1, B2, B3, and B4, and it is possible to prevent the occurrence of turbulence associated with the merge.

  In the negative pressure booster of this embodiment, the negative pressure valve seat 22 d is formed on the valve body 22 in an arc shape along the outer periphery of the plunger 32. For this reason, it is possible to sufficiently secure a passage through which air flows and to sufficiently improve the operation response. Further, as shown in FIG. 2, the plunger 32 is slidable in the axial direction on the valve body 22 at a front position and a rear position from a portion where each curved inclined surface (S1 to S4) is provided. It is supported by. For this reason, it is possible to support the plunger 32 stably.

  In the above-described embodiment, the curved surfaces S1 to S4 (the flow direction of the air flowing toward the variable pressure chamber R2 through the axial communication passages A1 to A4 is set in front of the axial communication passages A1 to A4 on the inner wall surface of the valve body 22. It was implemented by providing a portion that is bent and changed toward the radially inner ends of the radial communication passages B1 to B4 at the site, but the inner wall surface of the valve body is inclined (through the axial communication passage into the variable pressure chamber). The flow direction of the air flowing in the direction toward the radially inner end of the radial communication path at the front portion of the axial communication path may be provided.

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 the negative pressure type booster shown in FIG. 1 which expanded and showed the cross section along the 2-2 line of FIG. FIG. 3 is a cross-sectional view taken along line 3-3 of the valve body shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Housing, 20 ... Power piston, 21 ... Movable partition, 22 ... Valve body, 22a ... Shaft hole, 22c ... Key attachment hole, 22d ... Negative pressure valve seat, 22e ... Diverging wall, 22f ... Rib, 22g ... Guide wall, DESCRIPTION OF SYMBOLS 31 ... Input shaft, 32 ... Plunger, 32d ... Atmospheric valve seat, 34 ... Reaction member, 35 ... Output shaft, 39 ... Key member, 41 ... Valve body, 41a ... Negative pressure valve part, 41b ... Atmospheric valve part, A1-A4 ... Axial direction communication path, B1 to B4 ... Radial direction communication path, S1 to S4 ... Curved inclined surface, V ... Valve mechanism, R1 ... Negative pressure chamber, R2 ... Transformer chamber

Claims (7)

A valve body connected to a movable partition that divides the inside of the housing into a front negative pressure chamber and a rear variable pressure chamber has a shaft hole, and the shaft body advances and retreats in the axial direction with respect to the valve body. And a negative pressure valve for communicating / blocking between the negative pressure chamber and the variable pressure chamber and an atmospheric valve for communicating / blocking between the variable pressure chamber and the atmosphere according to the forward / backward movement of the plunger relative to the valve body. A valve mechanism is incorporated, and a reaction member in which a front end portion of the plunger and a front end portion of the valve body can engage with a rear surface, and a front end of the reaction member is engaged with a rear end portion with respect to the valve body. An output member movable in the axial direction is assembled, and when the plunger moves forward in the axial direction with respect to the valve body, the negative pressure valve is closed and the communication between the negative pressure chamber and the variable pressure chamber is established. The negative pressure type is configured such that the atmosphere valve is opened to communicate between the variable pressure chamber and the atmosphere, and the atmosphere flows into the variable pressure chamber through the axial communication path and the radial communication path provided in the valve body. In the booster,
The valve has an inclined surface that sequentially changes the flow direction of the air flowing toward the variable pressure chamber through the axial communication path toward the radially inner end of the radial communication path at a front portion of the axial communication path. A negative pressure booster provided on the inner wall surface of the body.   2. The negative pressure booster according to claim 1, wherein the inclined surface changes the flow direction of the air flowing toward the variable pressure chamber through the axial communication path at the front portion of the axial communication path. A negative pressure booster comprising a curved inclined surface that is sequentially bent and changed toward the radially inner end of the passage.   3. The negative pressure type booster according to claim 2, wherein a shunt wall that shunts the air flowing toward the variable pressure chamber through the axial communication passage in a circumferential direction at a front portion of the axial communication passage is formed on the valve body. A negative pressure booster characterized in that it is provided in a convex shape inward from the inner wall, and the curved inclined surface is formed on the flow dividing wall.   The negative pressure type booster according to claim 2, wherein a guide wall that forms the axial communication path with an inner wall of the shaft hole of the valve body is provided in a fan shape on the valve body along an outer periphery of the plunger. The negative pressure type booster is characterized in that the curved inclined surface is formed on the guide wall.   3. The negative pressure type booster according to claim 2, wherein a shunt wall that shunts air flowing toward the variable pressure chamber through the axial communication passage in a circumferential direction at a front portion of the axial communication passage, and the axial direction Guide walls that form communication passages with the inner wall of the shaft hole of the valve body are alternately provided in the valve body in the circumferential direction, and the flow direction is changed by the curved inclined surface formed in the flow dividing wall. A negative communicating path through which the atmospheric air flows and a radial communicating path through which the air whose flow direction is changed by the curved inclined surface formed in the guide wall flow are separately provided. Pressure booster.   The negative pressure type booster according to any one of claims 2 to 5, wherein a valve seat of the negative pressure valve is formed in the valve body in an arc shape along an outer periphery of the plunger. Negative pressure booster. The negative pressure type booster according to any one of claims 2 to 6, wherein the plunger slides in an axial direction on the valve body at a front position and a rear position from a portion where the curved inclined surface is provided. A negative pressure booster which is supported so as to be movable.

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