JP2017154566A - Negative-pressure type assistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simply-configured negative-pressure type assistor capable of increasing responsibility and an assistance force at an initial stage of emergency braking.SOLUTION: A negative-pressure type assistor includes a hollow housing composed of a front shell and a rear shell, a movable partition wall partitioning an interior of the housing, a valve body formed with an opening, a valve mechanism provided with an atmospheric valve to provide communication and interruption between a pressure change chamber and the atmosphere. The rear shell has a flange part at an opening end that is large in diameter, a cylindrical part connecting to a small diameter part of the flange part, and an annular seal portion that is a protrusion formed of elastomer and provided between the cylindrical part and the valve body so as to contact with or separate from the valve body thereby provide communication and interruption between the atmosphere and the pressure change chamber. The valve body is provided with a tapered part formed at least partly on an outer peripheral surface, the tapered part reducing in diameter as it goes to the opening.SELECTED DRAWING: Figure 2

Description

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

  The rear shell of this type of negative pressure booster has a flange portion with an open end tapered, and has a stepped portion composed of a small diameter portion connected to the flange portion and a large diameter portion larger in diameter than the small diameter portion. It has a cylindrical part. An annular seal portion is fixed to the inner peripheral side of the cylindrical portion, and a valve body is inserted so as to be in sliding contact with the seal portion. Some flange portions are configured so that a boot covering the outer periphery of the valve body is assembled. For example, it is described in Patent Document 1 below.

JP-T-2001-523621

  The rear shell of the negative pressure booster described in Patent Document 1 described above has a flange portion with an open end tapered, and a stepped cylindrical portion connected to the flange portion is formed. Further, an annular seal portion made of an elastic material is fixed to the inner peripheral side of the cylindrical portion, and a valve body is inserted so as to be slidable in contact with the seal portion. Furthermore, the negative pressure type booster device is provided in a control housing and includes a control valve for controlling a boost force (assisting force). The control valve is provided with an axially movable pressing member in the region of the reaction member. And it is supported by one side of an input member and a control housing. The pressing member is also detachably connected by the coupling member to increase the assisting action according to the relative movement between the input member and the control housing. This makes it possible to generate a large assisting force with good responsiveness when the driver needs it (initially during emergency braking).

  In the negative pressure type booster disclosed in Patent Document 1, it is necessary to dispose a pressing member and a coupling member in the control housing in order to generate an assisting force with good responsiveness at the initial stage of emergency braking. For this reason, the structure of the negative pressure type booster is complicated, which is a cause of deterioration in assemblability and high cost.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a negative pressure booster capable of increasing the responsiveness and assisting force at the initial stage of emergency braking with a simple configuration.

  In order to achieve the above object, an invention according to claim 1 is constituted by a hollow housing composed of a front shell and a rear shell, an annular plate and a diaphragm, and the inside of the housing has a front negative pressure chamber and a rear transformer. A movable partition wall partitioned into a chamber, a cylindrical valve body provided in the housing so as to be movable back and forth, and provided in a movable partition wall in the housing so as to be able to advance and retract, and having an opening for flowing in and out of the atmosphere; An air valve that is provided in a shaft hole formed in the valve body, can move forward and backward along the axial direction of the shaft hole with respect to the valve body, and moves integrally with the input member, and the air valve moves forward and backward with respect to the valve body. A negative pressure valve comprising a negative pressure valve that communicates and blocks between the negative pressure chamber and the variable pressure chamber and an atmospheric valve that communicates or blocks between the variable pressure chamber and the atmosphere. The rear shell has a flange portion to which a boot for covering the valve body is assembled at the open end, and has a cylindrical portion that is a small diameter portion connected to the small diameter portion of the flange portion, and the cylindrical portion and the valve body. And an annular seal portion made of an elastic material that shuts off or communicates between the atmosphere and the variable pressure chamber by abutting against or separating from the valve body. At least a portion is formed with a tapered portion that decreases in diameter toward the opening.

  According to the first aspect of the invention, for example, when the driver depresses the input member at a predetermined speed or more by emergency braking, that is, the elasticity toward the radially inner side for following the outer peripheral surface of the valve body of the seal portion. When the deformation speed is smaller than the radial reduction speed of the tapered portion caused by the axial movement of the valve body, the seal portion and the valve body are separated. As a result, an air inflow path is formed between the seal portion and the valve body, and the atmosphere communicates with the variable pressure chamber. Therefore, compared to the case where the seal portion is in contact with the valve body in the early stage of emergency braking, the initial stage of emergency braking is performed. The amount of air flowing into the variable pressure room can be increased with good responsiveness.

  Therefore, the responsiveness and assisting force of the negative pressure booster in the early stage of emergency braking can be improved with a simple structure. Thereafter, the seal portion is elastically deformed toward the outer peripheral surface of the valve body, and the normal pressure is applied by shutting off the atmosphere and the variable pressure chamber by contacting the valve body.

  Also, when the driver steps on the input member at a predetermined speed or less by normal braking, that is, the elastic deformation speed inward in the radial direction for the seal portion to follow the outer peripheral surface of the valve body by elastic deformation is the valve body shaft. When it is larger than the radial reduction speed of the taper portion caused by the direction movement, the seal portion can follow the outer peripheral surface of the valve body by elastic deformation. As a result, it is possible to prevent an unnecessary increase in assisting force during normal braking.

  The invention according to claim 2 is characterized in that the protrusion in the seal portion is formed in a plate shape in which the plate thickness becomes thicker toward the outer peripheral surface of the valve body.

  According to the invention which concerns on Claim 2, since the rigidity of the protrusion in a seal part goes up, the elastic deformation speed of the protrusion in a seal part can be suppressed in the operation | movement initial stage of a negative pressure type booster. Thereby, compared with the case where the protrusion part of a seal part is formed in uniform plate shape, the inflow amount and inflow time of the atmosphere in the early stage of emergency braking can be increased further, for example. Therefore, the responsiveness and assisting force of the negative pressure booster in the early stage of emergency braking can be further improved.

It is sectional drawing which shows 1st Embodiment of the negative pressure type booster in this invention. It is sectional drawing which shows the principal part enlarged view of FIG. It is sectional drawing which shows 2nd Embodiment of the negative pressure type booster in this invention.

  Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. 1 and 2 show a first embodiment of a negative pressure booster according to the present invention. In the negative pressure booster of this embodiment, a housing 10 is provided with a movable partition wall 20 and a valve body 30. Yes. The housing 10 is partitioned by a movable partition 20 into a front negative pressure chamber R1 and a rear variable pressure chamber R2.

  The housing 10 includes a front shell 11 and a rear shell 12. The housing 10 is airtightly provided on the front shell 11. The housing 10 is negatively connected to a negative pressure source (for example, an intake manifold of an engine not shown) at all times. A pressure introducing pipe 13 is provided. The housing 10 is fixed to a stationary member, that is, a vehicle body (not shown) by a plurality of mounting bolts 14 that pass through the rear shell 12 in an airtight manner, and a plurality of mounting bolts that pass through the front shell 11 in an airtight manner. A brake master cylinder (not shown) is configured to be supported.

  The brake master cylinder is a known one, and is airtightly assembled to the front shell 11 at the rear end. Further, the rear end portion of the brake master cylinder projects into the negative pressure chamber R1, and is configured to be pushed forward by a front end portion (not shown) of an output member 55 described later.

  The movable partition 20 assembled to the valve body 30 includes an annular metal plate 21 and an annular rubber diaphragm 22, and is movable in the front-rear direction (the axial direction of the valve body 30) within the housing 10. is set up. The diaphragm 22 is airtightly sandwiched between the housings 10 by an annular outer peripheral bead portion 22a formed on the outer peripheral edge thereof. The diaphragm 22 is airtightly fixed to the outer peripheral portion of the valve body 30 together with the inner peripheral portion of the plate 21 at an annular inner peripheral bead portion 22b formed on the inner peripheral edge thereof.

  The valve body 30 is a resin hollow body connected to the inner peripheral portion of the movable partition wall 20, and is airtight and movable in the front-rear direction to the rear shell 12 of the housing 10 at an intermediate portion formed in a cylindrical shape. It is assembled and urged rearward by a return spring S interposed between the housing 10 and the front shell 11. The portion of the valve body 30 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, the valve body 30 is formed with a stepped shaft hole 31 penetrating in the front-rear direction, communicating with the intermediate step portion of the shaft hole 31 at the rear end, and at the front end with the negative pressure chamber R1. A pair of negative communication passages 32 (only one of which is shown in FIG. 1) and a key attachment hole 33 that is substantially orthogonal to the front portion of the shaft hole 31 and allows the key member 41 to be inserted from the outer periphery are formed. ing.

  The input member 51 and the plunger 52 are coaxially assembled to the shaft hole 31 from the opening 34 which is an outflow / inflow path of the atmosphere, and the valve mechanism V and the filter 53 are coaxially assembled. . A rubber reaction member 54 and an output member 55 are coaxially assembled in the shaft hole 31 in front of the plunger 52.

  The input member 51 can move forward and backward with respect to the valve body 30, and is connected to the receiving connection portion of the plunger 52 in a joint shape at a spherical tip portion, and a brake pedal (not shown) via a yoke at a rear end screw portion. ) And is configured to receive a pedal force acting on the brake pedal as an input toward the front. The input member 51 is engaged with the spring 56 via a retainer locked to the intermediate step portion, and is urged rearward by the spring 56.

  The plunger 52 can be brought into contact with the central portion of the rear surface of the reaction member 54 at the tip portion, and can be engaged with the key member 41 by an annular groove portion formed in the middle portion thereof, and the tip portion is recoiled. This is the part that receives the reaction force of the output from the member 54 partially. An annular atmospheric valve seat in the valve mechanism V is formed at the rear end of the plunger 52.

  The output member 55 is assembled in the front end portion of the shaft hole 31 of the valve body 30 together with the reaction member 54 so as to be movable in the front-rear direction. During operation, the reaction force received from the brake master cylinder is transmitted to the reaction member 54.

  The key member 41 has a function of defining the forward / backward movement of the plunger 52 with respect to the valve body 30 and a function of defining a rearward movement limit position of the valve body 30 with respect to the housing 10 (rear return position of the valve body 30). Thus, the valve body 30 and the plunger 52 are assembled so as to be able to move relative to each other in the axial direction of the valve body 30.

  The valve mechanism V includes an arc-shaped or circular negative pressure valve seat integrally formed at the rear end portion of the negative pressure communication passage 32 in the valve body 30, and an annular atmospheric valve formed integrally at the rear end portion of the plunger 52. A seat and a cylindrical valve body 42 disposed coaxially with the atmospheric valve seat and assembled in the shaft hole 31 of the valve body 30 are provided. The valve body 42 has an annular mounting portion and a cylindrical movable portion that is integrally formed with the mounting portion and is movable in the axial direction.

  The attachment portion of the valve body 42 is airtightly assembled in the shaft hole 31 of the valve body 30, and is fixedly held at a fixed position (step portion) of the shaft hole 31 in the valve body 30 by the retainer 43. The retainer 43 is urged forward by a spring 56 and is fixed to a step portion of the shaft hole 31 in the valve body 30.

  The movable portion of the valve body 42 is a negative pressure valve portion that constitutes a negative pressure valve that can be seated / separated with respect to the negative pressure valve seat and can communicate / block between the negative pressure chamber R1 and the variable pressure chamber R2 by the negative pressure valve seat. And an annular atmospheric valve portion that constitutes an atmospheric valve that can be seated / separated with respect to the atmospheric valve seat and that can communicate / block between the variable pressure chamber R2 and the atmosphere by the atmospheric valve seat. The movable portion is biased forward by a compression spring 57.

  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 according to the movement of the input member 51 and the plunger 52 in the front-rear direction with respect to the valve body 30. That is, the input member 51 and the plunger 52 move forward from the original position (returning non-operating position) in FIG. 1 with respect to the valve body 30, the negative pressure valve portion is seated on the negative pressure valve seat, and the atmospheric valve seat is the atmospheric valve. When separated from the section, the variable pressure chamber R2 is disconnected from the negative pressure chamber R1 and communicates with the atmosphere. At this time, the air flows into the variable pressure chamber R2 through the vent hole 19a of the boot 19, the inside of the filter 53, the valve body 42, the gap between the air valve seat and the air valve portion, the communication path provided in the valve body 30, and the like. Therefore, in this embodiment, the movable partition 20 and the valve body 30 are operated forward and the output member 55 is operated forward as the input member 51 is operated forward.

  In addition, the input member 51 and the plunger 52 return to the return non-operating position (original position) with respect to the valve body 30, the atmospheric valve seat is seated on the atmospheric valve portion, and the negative pressure valve portion is separated from the negative pressure valve seat. In the state where the atmospheric valve is closed (that is, the communication between the variable pressure chamber R2 and the atmosphere is shut off and the negative pressure valve is opened and the negative pressure chamber R1 and the variable pressure chamber R2 are in communication) The chamber R2 is disconnected from the atmosphere and communicates with the negative pressure chamber R1. At this time, air is drawn from the variable pressure chamber R2 into the negative pressure chamber R1 through the communication passage provided in the valve body 30, the gap between the negative pressure valve portion and the negative pressure valve seat, the negative pressure communication passage 32, and the like. Therefore, in this embodiment, the movable partition 20 and the valve body 30 are operated rearward and the output member 55 is operated rearward as the input member 51 is operated rearward.

  FIG. 2 shows an enlarged view of the opening portion of the rear shell 12. In the present embodiment, the rear shell 12 is formed by pressing a steel plate (cold rolled steel plate), has a flange portion 12a having an opening end formed in a tapered shape, and has a small diameter portion continuous with the flange portion 12a. A cylindrical portion 12b having a large diameter portion larger than the small diameter portion is formed. Further, between the cylindrical portion 12b and the valve body 30, the metal plate portion 62 is assembled, and the plate portion 62 is disposed by being baked and fixed to the inner periphery of the cylindrical portion 12b. A seal portion 61 is provided. The seal portion 61 is made of an annular elastic material, and has a protrusion 60 that shuts off or communicates between the atmosphere and the variable pressure chamber by coming into contact with or separating from the valve body 30. Furthermore, the attachment part of the boot 19 is assembled | attached to the outer periphery of the flange part 12a.

  Further, a step portion 12 b 1 for positioning the key member 41 and the seal portion 61 is formed in the cylindrical portion 12 b of the rear shell 12. Further, a taper portion 35 is formed on the entire outer periphery of the valve body 30 on the opening 34 side from the contact portion with the protrusion 60 of the seal portion 61. The taper portion 35 can be set to an arbitrary length and inclination angle.

  In the negative pressure type booster of the present embodiment described above, for example, when the driver steps on the input member 51 at a predetermined speed or more by emergency braking, that is, for following the outer peripheral surface of the valve body 30 of the seal portion 61. When the elastic deformation rate directed radially inward is smaller than the radial reduction rate of the taper portion 35 caused by the axial movement of the valve body 30, the protrusion 60 of the seal portion 61 and the taper portion 35 are separated from each other. As a result, an air inflow path is formed between the seal portion 61 and the taper portion 35, and the atmosphere and the variable pressure chamber R2 are communicated with each other, so that the seal portion 61 is in contact with the valve body 30 in the early stage of emergency braking. In addition, the amount of air flowing into the variable pressure chamber R2 in the early stage of emergency braking can be increased with good responsiveness.

  Therefore, the responsiveness and assisting force of the negative pressure booster in the early stage of emergency braking can be improved with a simple structure. Thereafter, the seal portion 61 is elastically deformed toward the outer peripheral surface of the valve body 30, and the normal pressure is applied by shutting off the atmosphere and the variable pressure chamber R2 by coming into contact with the valve body 30.

  Further, when the driver steps on the input member 51 at a predetermined speed or less by normal braking, that is, the elastic deformation speed inward in the radial direction for the seal portion 61 to follow the outer peripheral surface of the valve body 30 by elastic deformation is the valve. When it is larger than the radial reduction speed of the taper portion generated by the axial movement of the body 30, the seal portion 61 can follow the outer peripheral surface of the valve body 30 by elastic deformation. Thereby, it is possible to prevent an increase in unnecessary assisting force during normal braking.

  Next, a negative pressure type booster according to a second embodiment of the present invention will be described with reference to FIG. 3 focusing on the differences from the first embodiment.

  In this embodiment, the protrusion 60 in the seal portion 61 is formed in a plate shape having a plate thickness portion 63 that increases in thickness toward the outer peripheral surface of the valve body 30.

  Thereby, since the rigidity increases in the plate thickness portion 63 of the protrusion 60, the elastic deformation speed of the protrusion 60 on the radially inner side of the protrusion 60 in the seal portion 61 can be suppressed in the initial stage of emergency braking of the negative pressure booster. Thereby, compared with the case where the protrusion part 60 of the seal | sticker part 61 is formed in a uniform plate shape, the inflow amount and inflow time of the air | atmosphere at the initial stage of emergency braking can be increased, for example. Therefore, the responsiveness and output of the negative pressure booster in the early stage of emergency braking can be further improved.

  In the embodiment described above, the taper portion of the valve body is a negative pressure booster formed on the entire circumference of the valve body, but the taper portion of the valve body is a part of the outer peripheral surface of the valve body. It may be formed and implemented.

  Further, in the above-described embodiment, the negative pressure type booster device in which the taper portion of the valve body is formed in one place is shown, but the taper portion may be formed in a plurality of places in the valve body.

  As described above, it is possible to carry out by appropriately changing the shape and number of each member within the scope described in the claims.

  DESCRIPTION OF SYMBOLS 10 ... Housing, 11 ... Front shell, 12 ... Rear shell, 12a ... Flange part, 12b ... Cylindrical part, 12b1 ... Step part, 20 ... Movable partition, 21 ... Plate, 22 ... Diaphragm, 30 ... Valve body, 31 ... Shaft hole 32 ... Negative pressure communication path, 34 ... Opening part, 35 ... Taper part, 36 ... Slit part, 51 ... Input member, 52 ... Plunger, 55 ... Output member, 60 ... Projection part, 61 ... Seal part, 63 ... Plate thickness Part, V ... valve mechanism, R1 ... negative pressure chamber, R2 ... transformer chamber

Claims (2)

A hollow housing composed of a front shell and a rear shell;
A movable partition configured by an annular plate and a diaphragm, and partitioning the inside of the housing into a front negative pressure chamber and a rear transformer chamber;
A tubular valve body provided in the housing so as to be capable of advancing and retreating, and provided in the housing so as to be capable of advancing and retreating, and having an opening through which air flows in and out;
An air valve provided in a shaft hole formed in the valve body, capable of moving back and forth along the axial direction of the shaft hole with respect to the valve body, and moving integrally with the input member;
A negative pressure valve that communicates and blocks between the negative pressure chamber and the variable pressure chamber in accordance with advancement and retreat of the air valve relative to the valve body, and an atmospheric valve that communicates or blocks between the variable pressure chamber and the atmosphere. A negative pressure booster comprising a valve mechanism,
The rear shell has a flange portion to which a boot for covering the valve body is assembled at an open end, and a cylindrical portion that is a small diameter portion connected to a small diameter portion of the flange portion,
From an elastic material that is interposed between the cylindrical portion and the valve body, and that has a protrusion that shuts off or communicates between the atmosphere and the variable pressure chamber by contacting or separating from the valve body. An annular seal portion,
A negative pressure type booster characterized in that a taper portion whose diameter decreases toward the opening is formed on at least a part of the outer peripheral surface of the valve body. 2. The negative pressure type booster according to claim 1, wherein the projecting portion of the seal portion is formed in a plate shape in which a plate thickness increases as it goes toward an outer peripheral surface of the valve body.