JP2019006300A - Air pressure type booster - Google Patents

Abstract

To provide an air pressure type booster with a reduced weight.SOLUTION: A front chamber A in a housing 2 is divided into a front side constant pressure chamber A1 and a front side variable pressure chamber A2 by a front side power piston 25. On the other hand, a rear chamber B in the housing 2 is divided into a rear side constant pressure chamber B1 and a rear side variable pressure chamber B2 by a rear side power piston 28. The rear side power piston 28 comprises: a rear side diaphragm 29; and a rear side piston member 32 positioned at the rear side constant pressure chamber B1 side and formed along the rear side diaphragm 29. The rear side diaphragm 29 is provided with protruding parts 30 protruding toward the interior of the rear side variable pressure chamber B2. A space part 30B is formed between each protruding part 30 and the rear side piston member 32.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pneumatic booster used in a vehicle brake device.

  In general, a brake system of a vehicle is provided with a pneumatic booster between a brake pedal and a master cylinder. This type of pneumatic booster boosts the pedal force applied from the brake pedal to the input rod according to the pressure difference between the internal constant pressure chamber and the variable pressure chamber. (See Patent Document 1).

JP 2004-58959 A

  By the way, the pneumatic booster according to Patent Document 1 reduces the capacity of the variable pressure chamber to improve the responsiveness of the brake operation. As another method, a part of the diaphragm that defines the interior of the housing into a constant pressure chamber and a variable pressure chamber is built up on the variable pressure chamber side, so that the capacity of the variable pressure chamber is reduced and the response of the brake operation is reduced. A structure that improves the above can also be considered. However, this structure may increase the weight and cost of the pneumatic booster.

  Therefore, an object of the present invention is to provide a pneumatic booster that is lightened.

  In order to solve the above-described problems, a pneumatic booster according to the present invention includes a housing composed of a plurality of shells, a diaphragm that defines the inside of the housing into a constant pressure chamber and a variable pressure chamber, and a power piston together with the diaphragm. A piston member formed along the diaphragm located on the constant pressure chamber side, a valve body connected to the power piston and moving in the housing, one end side connected to a brake pedal and the other end side to the valve body An input rod extending inward, a plunger disposed in the valve body and connected to the input rod, and the input rod moves the plunger to introduce a working gas into the variable pressure chamber, thereby the constant pressure chamber. And a valve means for generating a pressure difference between the variable pressure chamber and the power piston due to the pressure difference. And an output rod on which the thrust is applied, wherein the diaphragm is provided with a projecting portion projecting into the variable pressure chamber, and between the projecting portion and the piston member. Is characterized in that a space is formed.

  According to the present invention, the pneumatic booster can be reduced in weight.

The longitudinal section showing the air pressure type booster by an embodiment. The front view which shows a rear side diaphragm independently. Sectional drawing which expanded and looked at the rear side diaphragm in FIG. 2 from arrow III-III direction. Sectional drawing which expands and shows the (IV) part of the rear side diaphragm in FIG.

  Hereinafter, a tandem type pneumatic booster applied to a brake device for a vehicle will be described as an example and described in detail with reference to the accompanying drawings.

  In FIG. 1, a pneumatic booster 1 has a housing 2 composed of a plurality of shells. Specifically, the housing 2 includes a front shell 3 positioned closer to the front side of the vehicle (not shown), a rear shell 4 connected to the rear end side of the front shell 3, and a space between the front shell 3 and the rear shell 4. And a center shell 5 that defines the inside of the housing 2 into two chambers, a front chamber A and a rear chamber B. The shells 3, 4, and 5 are attached to each other on the outer peripheral side in an airtight state.

  The front shell 3 includes a front wall 3A serving as a mounting surface for a master cylinder (not shown), and an outer peripheral cylindrical portion 3B extending rearward from a radially outer end portion of the front wall 3A. Yes. A cylindrical recess 3A1 for accommodating a part of the master cylinder is formed at the center of the front wall 3A. The cylindrical recess 3A1 is provided with an annular seal member (not shown) that hermetically seals with the master cylinder. This seal member seals the front-side constant pressure chamber A1 in the housing 2 in an airtight state against the outside atmosphere. Further, the front wall 3A has a negative pressure introduction communicating with a front side insertion hole 3A2 which is located radially outside the cylindrical recess 3A1 and through which a rod member 22 described later is inserted, and a negative pressure introducing tube 21 described later. A hole 3A3 is formed.

  The rear shell 4 includes a rear wall 4A serving as a mounting surface for a vehicle body (not shown), a rear cylinder portion 4B protruding outward in the axial direction from a center portion of the rear wall 4A, and a radially outer end of the rear wall 4A. And an outer peripheral cylindrical portion 4C extending forward from the portion.

  The rear wall 4A is formed with a rear side insertion hole 4A1 that is located radially outside the rear cylinder portion 4B and into which a rod member 22 described later is inserted. An annular stepped portion 4B1 is provided in the middle of the rear cylinder portion 4B in the axial direction (length direction). A stop key 16, which will be described later, comes into contact with the stepped portion 4B1 when a pushing operation of the input rod 8, which will be described later, is released, thereby restricting the return positions of the valve body 6 and the plunger 14 described later. The outer peripheral cylindrical portion 4C extends forward from the rear wall 4A, and is connected to the front shell 3 and the center shell 5 on the tip side. Further, a rear diaphragm 29 described later is fixed to the center shell 5 at the front end side of the outer peripheral cylindrical portion 4C.

  The center shell 5 is located between the front shell 3 and the rear shell 4, and the radially outer end is connected to the front end side of the rear shell 4. The center shell 5 is defined in the housing 2 into a front chamber A formed between the front shell 3 and the center shell 5 and a rear chamber B formed between the rear shell 4 and the center shell 5. Yes. Further, a valve body insertion hole 5A through which a later-described valve body 6 is inserted is formed in the center portion of the center shell 5, and a later-described tubular member 24 is provided at a position on the radially outer side of the valve body insertion hole 5A. A cylindrical member attachment hole 5B is formed to hold one end side.

  The valve body 6 is inserted into the rear cylinder portion 4B of the rear shell 4. The valve body 6 is provided in the housing 2 so as to be able to be displaced (moved) in the axial direction (left and right directions in FIG. 1). The valve body 6 is formed in a stepped shape by using, for example, a high-strength resin material and a main body portion 6A located on the master cylinder side and a small-diameter cylindrical portion 6B located on the vehicle body attachment side.

  The main body portion 6A of the valve body 6 is slidably fitted into the valve body insertion hole 5A of the center shell 5 via the seal member 7. The front end side of the main body 6A is located in the front chamber A and connected (fixed) to the inner peripheral side of the front power piston 25 described later. Further, the rear end side of the main body portion 6A is located in the rear chamber B and connected (fixed) to the inner peripheral side of the rear power piston 28 described later.

  On the other hand, the small-diameter cylindrical portion 6B of the valve body 6 extends from the rear cylindrical portion 4B of the rear shell 4 toward the outside of the housing 2 on the vehicle body attachment side (right side in FIG. 1). The valve body 6 moves (displaces) in the axial direction in the housing 2 in conjunction with displacement of a front power piston 25 and a rear power piston 28 described later.

  The valve body 6 is always in communication with the front constant pressure chamber A1 and has an axial passage 6C extending in the axial direction from the main body portion 6A toward the small-diameter cylindrical portion 6B, and the axial passage 6C and the rear constant pressure chamber B1. A communicating radial passage 6D is formed. That is, the front constant pressure chamber A1 of the front chamber A and the rear constant pressure chamber B1 of the rear chamber B are always in communication with each other by the axial passage 6C and the radial passage 6D of the valve body 6.

  Further, another radial passage 6E is formed in the small diameter cylindrical portion 6B of the valve body 6 at a position different from the axial passage 6C and the radial passage 6D. The radial passage 6E is always in communication with the front variable room A2 and the rear variable room B2. The axial passage 6C, the radial passage 6D, and the radial passage 6E are, as the valve body 6 moves in the axial direction, the front constant pressure chamber A1, the rear constant pressure chamber B1, the front variable pressure chamber A2, and the rear variable pressure chamber. The chamber B2 is communicated and shut off via a poppet valve body 9 and a plunger 14 which will be described later.

  Further, a key insertion hole 6F is formed in the valve body 6 at a position corresponding to the step portion 4B1 of the rear shell 4. A stop key 16 described later is inserted into the key insertion hole 6F. The valve body 6 is formed with an annular valve seat 6G at the opening end of the axial passage 6C on the vehicle body mounting side. The valve seat portion 6G is configured such that a later-described poppet valve body 9 is seated and separated, and constitutes a part of the valve means of the present invention. The valve body 6 is integrally formed with a cylindrical projecting portion 6H that is located on the inner peripheral side of the main body portion 6A and projects in the axial direction toward the output rod 17 described later.

  The input rod 8 has one end connected to a brake pedal (not shown) and the other end extending toward the inside of the valve body 6. That is, the input rod 8 protrudes outward from the rear cylinder portion 4B of the rear shell 4 on the vehicle body mounting side, and is inserted into the small diameter cylinder portion 6B of the valve body 6 on the master cylinder side (left side in FIG. 1). This input rod 8 is pushed in the direction of arrow C in FIG. Further, a spherical portion 8A is integrally formed on the distal end side of the input rod 8, and this spherical portion 8A is connected to a plunger 14 described later by means such as caulking.

  The poppet valve body 9 is provided in the small diameter cylindrical portion 6 </ b> B of the valve body 6 so as to be positioned on the outer peripheral side of the input rod 8. The poppet valve body 9 is formed in a substantially cylindrical shape by an elastic material, and the vehicle body mounting side is pressed and fixed to the inner peripheral side of the valve body 6 by a return spring 11 described later. The master cylinder side of the poppet valve body 9 is constantly urged toward the valve seat portion 6G of the valve body 6 by the weak spring 10. The poppet valve body 9 is separated from and seated on a valve seat portion 6G of the valve body 6 and a contact portion 14A of a plunger 14 described later, and introduces working gas into the front variable chamber A2 and the rear variable chamber B2. This constitutes part of the valve means of the present invention for generating a pressure difference between the front constant pressure chamber A1 and the front variable pressure chamber A2, and the rear constant pressure chamber B1 and the rear variable pressure chamber B2.

  The return spring 11 is disposed between the small diameter cylindrical portion 6 </ b> B of the valve body 6 and the input rod 8. The return spring 11 constantly biases the input rod 8 toward the vehicle body mounting side with respect to the valve body 6. As a result, when the pushing operation (braking operation) on the input rod 8 is released, the valve body 6 moves in the direction indicated by the arrow D in the housing 2 and is regulated by an initial position shown in FIG. The input rod 8 is pressed by the return spring 11 until it returns to the position).

  The filter 12 is attached to the vehicle body attachment side opening (the working gas introduction opening) of the valve body 6. The filter 12 purifies air as working gas introduced from the outside of the housing 2 into the small diameter cylindrical portion 6 </ b> B of the valve body 6, and suppresses dust and the like from entering the housing 2. The protective boot 13 mounted on the outer peripheral side of the small-diameter cylindrical portion 6B of the valve body 6 is formed as an accordion-shaped cylindrical body with an elastic material, and protects the protruding end side of the valve body 6 from external dust and the like.

  The plunger 14 is fixed to the spherical portion 8 </ b> A of the input rod 8, and is fitted on the inner peripheral side of the valve body 6 so as to be movable (displaceable) in the axial direction. That is, the plunger 14 is configured to be displaced in the axial direction integrally with the input rod 8. An abutting portion 14 </ b> A that is attached to and detached from the poppet valve body 9 is provided on the body mounting side (rear end) of the plunger 14. The contact portion 14A of the plunger 14 is separated from and seated on the poppet valve body 9 so that the working gas (atmospheric pressure) introduced into the small-diameter cylindrical portion 6B of the valve body 6 via the filter 12 is on the radial passage 6E side. Introduce into the air or block air introduction.

  That is, the plunger 14 communicates and blocks the front variable pressure chamber A2 and the rear variable pressure chamber B2 with respect to the atmospheric pressure in the small diameter cylindrical portion 6B of the valve body 6 by the contact portion 14A being seated on and away from the poppet valve body 9. Do. Further, when the poppet valve body 9 is separated from and seated on the valve seat 6G of the valve body 6, the front variable pressure chamber A2 and the rear variable pressure chamber B2 are connected to and disconnected from the front constant pressure chamber A1 and the rear constant pressure chamber B1. An annular groove is formed on the outer peripheral side of the plunger 14 at a position corresponding to the key insertion hole 6F of the valve body 6, and a stop key 16 described later is attached to the annular groove in an engaged state.

  The moving body 15 constituting a part of the plunger 14 moves (displaces) in the axial direction within the cylindrical protrusion 6H of the valve body 6. The front end side (master cylinder side) of the moving body 15 is inserted into the inner peripheral side of the cylindrical protrusion 6H of the valve body 6 and abuts on a reaction disk 20 described later.

  The stop key 16 is formed using a substantially rectangular flat plate, and is engaged with the plunger 14 in a loosely fitted state via the key insertion hole 6F of the valve body 6. An end portion of the stop key 16 projects from the valve body 6 by a certain dimension in the radial direction, and can abut on the annular step portion 4B1 of the rear shell 4. That is, when the pushing operation on the input rod 8 is released, the stop key 16 abuts on the step portion 4B1 of the rear shell 4 to restrict the return positions of the valve body 6 and the plunger 14 as shown in FIG.

  The output rod 17 outputs to the master cylinder in a state where the pushing operation force of the input rod 8 is boosted. The output rod 17 is provided with a large-diameter flange portion 17A on the vehicle body attachment side. The flange portion 17A is fitted to the cylindrical projecting portion 6H of the valve body 6 so as to cover the cylindrical projecting portion 6H of the valve body 6 via a reaction disk 20 described later.

  When the input rod 8 is pushed, the output rod 17 is moved together with the valve body 6 by the pressure difference between the front constant pressure chamber A1 and the front variable pressure chamber A2 and the rear constant pressure chamber B1 and the rear variable pressure chamber B2. It is pushed with a large output in the direction of arrow C in the middle. That is, the master cylinder side of the output rod 17 projects in the axial direction toward the cylindrical recess 3A1 of the front shell 3, and the piston of the master cylinder (output) is a force (output) obtained by multiplying the pushing operation force of the input rod 8. (Not shown) is configured to press in the axial direction.

  The spring receiver 18 is located on the inner peripheral side of the main body portion 6A of the valve body 6 and is attached to the outer peripheral side of the cylindrical protruding portion 6H via the flange portion 17A of the output rod 17. The spring receiver 18 is configured to prevent the flange portion 17 </ b> A from being removed from the cylindrical protruding portion 6 </ b> H together with the return spring 19. Here, the return spring 19 is disposed between the spring receiver 18 and the cylindrical recess 3A1 of the front shell 3, and constantly biases the valve body 6 toward the vehicle body mounting side.

  The reaction disk 20 is disposed between the cylindrical protrusion 6H of the valve body 6 and the flange portion 17A of the output rod 17. The reaction disk 20 is formed in a disk shape using an elastically deformable rubber material or the like. The reaction disk 20 applies the thrust generated in the valve body 6 to the output rod 17 due to the pressure difference generated between the front constant pressure chamber A1 and the front variable pressure chamber A2, and the rear constant pressure chamber B1 and the rear variable pressure chamber B2. introduce. The reaction disk 20 receives the reaction force from the output rod 17 and transmits a part of the reaction force to the input rod 8 side via the plunger 14 to give a response to the driver on the brake pedal side. .

  The negative pressure introduction pipe 21 is composed of a pipe or the like communicating with the negative pressure introduction hole 3A3 formed in the front wall 3A of the front shell 3, and is connected to the intake manifold of the engine via a check valve (none of which is shown). It is connected. The negative pressure introduction pipe 21 guides the negative pressure generated in the intake manifold during the operation of the engine to the front constant pressure chamber A1 and the rear constant pressure chamber B1, so that the inside of the front constant pressure chamber A1 and the rear constant pressure chamber B1. The inside is kept at a pressure lower than atmospheric pressure.

  The rod member 22 is formed as a solid cylinder extending in the axial direction between the front chamber A and the rear chamber B in the housing 2. The front end side of the rod member 22 protrudes from the front side insertion hole 3A2 of the front shell 3 and is fixed to the master cylinder. On the other hand, the rear end side of the rod member 22 protrudes from the rear side insertion hole 4A1 of the rear shell 4 and is fixed to the vehicle body. That is, the rod member 22 is provided so as to penetrate the rear shell 4 from the front shell 3 through the center shell 5, and is used to attach the pneumatic booster 1 to the vehicle body (vehicle) and the master cylinder. For example, two rod members 22 (only one is shown) are provided on the outer peripheral side of the small-diameter cylindrical portion 6B of the valve body 6 so as to be separated in the circumferential direction.

  A front power piston 25 described later is slidably attached to a portion of the rod member 22 located on the front chamber A side. Further, the central portion of the rod member 22 is inserted through a cylindrical member mounting hole 5B of the center shell 5 through a cylindrical member 24 described later. A portion of the rod member 22 located on the rear chamber B side is inserted into a through hole 24A of a cylindrical member 24 described later.

  Two vehicle body mounting bolts 23 (for example, only one is shown in FIG. 1) are provided on the radially outer side of the small diameter cylindrical portion 6B of the valve body 6, for example. Thereby, the pneumatic booster 1 is attached to the vehicle body (not shown) by the rear end sides of the two rod members 22 and the two vehicle body mounting bolts 23 and is not shown by the front end sides of the two rod members 22. It is configured to be attached to the master cylinder.

  The cylindrical member 24 is supported in a state where the front end side is fixed to the cylindrical member mounting hole 5B of the center shell 5 and the rear end side is passed through a cylindrical member through hole 29C of the rear diaphragm 29 described later. That is, the rear power piston 28 can slide in the axial direction along the outer peripheral surface of the cylindrical member 24. The inner peripheral side of the cylindrical member 24 is a through hole 24 </ b> A extending in the axial direction. As shown in FIG. 1, the through hole 24A is formed as a circular hole whose front end opens to the front variable chamber A2 and whose rear end opens to the rear variable chamber B2.

  The hole diameter of the through hole 24 </ b> A is formed larger than the outer diameter dimension of the rod member 22. Thereby, the clearance gap between the rod member 22 and 24 A of through-holes is a communicating path which connects the front side transformation room A2 and the rear side transformation room B2. Therefore, the front variable chamber A2 of the front chamber A communicates with the radial passage 6E of the valve body 6 via the communication path and the rear variable chamber B2.

  Next, the front power piston 25 and the rear power piston 28 provided in the housing 2 will be described.

  The front power piston 25 is provided in the front chamber A in the housing 2. The front power piston 25 is fixed at an intermediate portion in the front and rear directions of the housing 2 on the outer peripheral side (radially outer side) between the front shell 3 and the center shell 5 and on the inner peripheral side (radially inner side). The front diaphragm 26 is fixed to the front end side of the body 6, and the front piston member 27 extends from the front end side of the valve body 6 toward the radially outer side along the front surface 26 </ b> A of the front diaphragm 26.

  In this case, the front diaphragm 26 defines the front chamber A of the housing 2 as a front constant pressure chamber A1 and a front variable pressure chamber A2. Thus, in the front chamber A, a space between the front shell 3 and the front diaphragm 26 is a front constant pressure chamber A1, and a space between the front diaphragm 26 and the center shell 5 is a front variable chamber A2.

  The front diaphragm 26 has a valve body locking hole 26 </ b> B in which the inner peripheral side (center opening) locks the front end side of the valve body 6. Further, the front diaphragm 26 is formed with rod member through holes 26C (only one is shown in FIG. 1) through which the two rod members 22 pass radially outward from the valve body locking hole 26B.

  The front piston member 27 is a plate made of, for example, a metal material, and the inner peripheral side is locked to the front end side of the valve body 6, and the outer peripheral side extends along the front surface 26 </ b> A of the front diaphragm 26 to a middle portion of the front diaphragm 26. Yes. The front piston member 27 is a reinforcing member that reinforces the front diaphragm 26. The front power piston 25 (the front diaphragm 26 and the front piston member 27) is displaced (moved) in the front chamber A in the front and rear directions by the pressure difference between the front constant pressure chamber A1 and the front variable chamber A2 together with the valve body 6. )

  The rear power piston 28 is provided in the rear chamber B in the housing 2. The rear power piston 28 has an outer peripheral side (radially outer side) fixed on the front end side of the rear shell 4 between the rear shell 4 and the center shell 5, and an inner peripheral side (radially inner side) of the body portion of the valve body 6. A rear diaphragm 29 fixed to the rear end side (vehicle body attachment side) of 6A, and a rear extending from the rear end side of the body portion 6A of the valve body 6 toward the radially outer side along the front surface 29A of the rear diaphragm 29. The side piston member 32 is used.

  In this case, the rear diaphragm 29 defines the rear chamber B of the housing 2 as a rear constant pressure chamber B1 and a rear variable chamber B2. Thus, in the rear chamber B, a space between the center shell 5 and the rear diaphragm 29 is a rear constant pressure chamber B1, and a space between the rear diaphragm 29 and the rear shell 4 is a rear variable chamber B2.

  As shown in FIGS. 1 to 3, the rear diaphragm 29 has a valve body locking hole 29 </ b> B that locks the rear end side of the main body 6 </ b> A of the valve body 6 on the inner peripheral side (center opening). ing. Further, the rear diaphragm 29 is formed with a cylindrical member through-hole 29C through which the two rod members 22 penetrate each radially outer side than the valve body locking hole 29B.

  Here, the rear diaphragm 29 is provided with a hollow projecting portion 30 that projects so as to bulge out into the rear transformer chamber B2. As shown in FIG. 2, for example, four protrusions 30 are provided spaced apart in the circumferential direction between two cylindrical member through holes 29 </ b> C. Each protrusion 30 is formed in a fan shape that is curved in the circumferential direction between two cylindrical member through holes 29C. Each protrusion 30 is formed in a concave shape with an opening 30 </ b> A on the front side, and the opening 30 </ b> A is closed by a rear piston member 32.

  The protruding portion 30 protrudes toward the rear variable room B2, thereby reducing the capacity of the rear variable room B2. Moreover, as shown in FIG. 2, the protrusion part 30 is formed so that the two cylindrical member through-holes 29C may be surrounded in the circumferential direction. As a result, the working gas (atmosphere) introduced from the inside of the valve body 6 into the rear variable chamber B2 through the radial passage 6E is promptly guided to the through hole 24A of the cylindrical member 24 by the protrusion 30. Therefore, during operation of the brake, the working gas (atmosphere) can be introduced into the rear transformer room B2 and the working gas (atmosphere) into the front transformer room A2. Can be improved.

  Here, a space 30 </ b> B is formed between the protrusion 30 and the rear piston member 32. Thereby, the rear diaphragm 29 can reduce a weight compared with the case where the space | interval between the protrusion part 30 and the rear side piston member 32 is made solid. The size and the number of the protrusions 30 can be appropriately set by experiments or the like in consideration of responsiveness during brake operation.

  As shown in FIG. 2, the space 30 </ b> B is divided into a plurality of ribs 31 that extend from the protrusion 30 of the rear diaphragm 29 toward the rear piston member 32 (front side). That is, the rib 31 divides the space portion 30B into a plurality of chambers, for example, by forming the space portion 30B so as to extend in the circumferential direction and the radial direction. The number of the space portions 30 </ b> B is divided into, for example, 3 to 20 pieces, preferably 5 to 10 pieces depending on the arrangement of the ribs 31.

  The leading end portion 31 </ b> A (front end portion) of the rib 31 is in contact with the rear piston member 32. Thereby, the rib 31 is a reinforcing member that suppresses the deformation of the protrusion 30 when the rear power piston 28 is displaced. The number and thickness dimensions of the ribs 31 can be appropriately set by experiments or the like in consideration of the size of the protruding portion 30 and the deformation of the protruding portion 30.

  The rear piston member 32 is a plate formed of, for example, a metal material, and the inner peripheral side is locked to the rear end side of the main body portion 6A of the valve body 6, and the outer peripheral side reaches the middle part of the rear diaphragm 29. It extends along the front surface 29A. In this case, the rear piston member 32 closes the opening 30 </ b> A of the protrusion 30 at the portion of the protrusion 30 of the rear diaphragm 29. The rear piston member 32 is a reinforcing member that reinforces the rear diaphragm 29. The rear power piston 28 (rear diaphragm 29 and rear piston member 32) is moved forward and rearward in the rear chamber B by the pressure difference between the rear constant pressure chamber B1 and the rear variable chamber B2 together with the valve body 6. Displace (move) in the direction.

  The pneumatic booster 1 according to the present embodiment has the above-described configuration, and the operation thereof will be described next.

  First, the pneumatic booster 1 defines the inside of a housing 2 into a front chamber A and a rear chamber B by a center shell 5, and the front constant pressure chamber A1 in the front chamber A by a front power piston 25 (front diaphragm 26). And the front variable chamber A2, and the rear chamber B is defined by the rear power piston 28 (rear diaphragm 29) as the rear constant pressure chamber B1 and the rear variable chamber B2. It is a pneumatic booster.

  When the driver of the vehicle depresses the brake pedal, the input rod 8 is pushed in the direction indicated by the arrow C, and the plunger 14 is displaced along with the moving body 15 in the axial direction. In this case, since the movement of the poppet valve body 9 is restricted by the valve seat portion 6G of the valve body 6, the contact portion 14A of the plunger 14 is separated from the poppet valve body 9. As a result, atmospheric pressure (working gas) is introduced into the rear variable chamber B2 from the small diameter cylindrical portion 6B of the valve body 6 via the radial passage 6E, and the large pressure introduced into the rear variable chamber B2. The atmospheric pressure is introduced into the front side variable pressure chamber A <b> 2 through the through hole 24 </ b> A of the cylindrical member 24. As a result, a pressure difference is generated between the front constant pressure chamber A1 and the front variable pressure chamber A2 and between the rear constant pressure chamber B1 and the rear variable pressure chamber B2.

  For this reason, the valve body 6 has a thrust generated in the front power piston 25 due to a pressure difference between the front constant pressure chamber A1 and the front variable pressure chamber A2, and a pressure between the rear constant pressure chamber B1 and the rear variable pressure chamber B2. It moves forward to the master cylinder side (left side in FIG. 1) with the thrust generated in the rear power piston 28 due to the difference. The thrust at this time is transmitted from the valve body 6 to the output rod 17 via the reaction disk 20, and the piston of the master cylinder connected to the output rod 17 is pushed in the axial direction within the cylinder body.

  As a result, a brake fluid pressure corresponding to the stroke of the output rod 17 is generated in the cylinder body of the master cylinder, and this brake fluid pressure is applied to each wheel side wheel cylinder (is (Not shown). As a result, a braking force is applied to each wheel of the vehicle.

  On the other hand, when the brake operation is released, the input rod 8 is pushed back in the direction indicated by the arrow D by the return spring 11, and accordingly, the plunger 14 is pulled together with the moving body 15 in the same direction. At this time, the contact portion 14A of the plunger 14 is seated on the poppet valve body 9, and blocks the front variable chamber A2 and the rear variable chamber B2 from the outside atmosphere. However, since the plunger 14 presses the poppet valve body 9 against the weak spring 10 in the direction indicated by the arrow D, the plunger 14 separates the poppet valve body 9 from the valve seat portion 6G of the valve body 6.

  As a result, the front side constant pressure chamber A1 and the rear side constant pressure chamber B1, and the front side variable pressure chamber A2 and the rear side variable pressure chamber B2 communicate with each other through the axial passage 6C, the radial passages 6D, 6E, and the like. The negative pressure in the chamber A1 and the rear constant pressure chamber B1 is introduced into the front variable pressure chamber A2 and the rear variable pressure chamber B2. As a result, the front side constant pressure chamber A1 and the front side variable pressure chamber A2 and the rear side constant pressure chamber B1 and the rear side variable pressure chamber B2 have a pressure difference lower than the pressure difference before the brake operation is released. Accordingly, the output rod 17 is pushed back together with the valve body 6 by the return spring 19 in the direction indicated by the arrow D, and finally the protruding end side of the stop key 16 abuts on the stepped portion 4B1 of the rear shell 4 as shown in FIG. .

  Then, with the stop key 16 in contact with the step portion 4B1, the final return position of the plunger 14 is restricted, and the front power piston 25, the rear power piston 28, the valve body 6, the input rod 8, the output rod 17, etc. Returns to the initial position shown in FIG. Further, the poppet valve body 9 is seated on the valve seat portion 6G of the valve body 6 and the contact portion 14A of the plunger 14, and the front variable pressure chamber A2 and the rear variable pressure chamber B2 are connected to the front constant pressure chamber A1 and the rear constant pressure chamber B1. The next brake operation is prepared while maintaining the same negative pressure state.

  By the way, in the above-described prior art, the rear diaphragm is provided with a protruding portion that protrudes toward the rear transformer chamber, thereby reducing the capacity of the rear transformer chamber and improving the responsiveness during brake operation. . However, since the protruding portion is solid with the rear diaphragm being built up toward the rear transformer chamber, there is a possibility that the weight and the cost of the pneumatic booster increase.

  Therefore, in the present embodiment, the rear diaphragm 29 is provided with a hollow protrusion 30 that protrudes into the rear variable chamber B2, and the inside of the protrusion 30 is formed as a space 30B. Thereby, the weight of the rear diaphragm 29 can be reduced, and the cost can be reduced.

  The space 30 </ b> B is divided into a plurality of chambers by ribs 31 extending from the protrusion 30 toward the rear piston member 32. The tip 31A of the rib 31 is in contact with the rear piston member 32. Thereby, the rib 31 can suppress the deformation of the protrusion 30 when the rear power piston 28 is displaced. That is, when the brake operation is performed and the working gas (atmosphere) is introduced into the rear transformer chamber B2, the rib 31 suppresses the deformation of the projecting portion 30, so the capacity in the rear transformer chamber B2 is reduced. Can be maintained as is. Further, the working gas introduced into the rear side variable chamber B2 can be quickly introduced into the front side variable chamber A2 through the through hole 24A of the cylindrical member 24. Therefore, the responsiveness at the time of brake operation can be improved.

  In the above-described embodiment, the case where the protrusion 30 is provided on the rear diaphragm 29 has been described as an example. However, the present invention is not limited to this. For example, the protrusion 30 may be provided on the front diaphragm 26.

  In the embodiment described above, the inside of the housing 2 is defined by the center shell 5 into the front chamber A and the rear chamber B, and the front chamber A is separated from the front constant pressure chamber A1 and the front side by the front power piston 25 (front diaphragm 26). A tandem type pneumatic booster defined in the variable pressure chamber A2 and defined in the rear constant pressure chamber B1 and the rear variable pressure chamber B2 by the rear power piston 28 (rear diaphragm 29) in the rear chamber B. The apparatus 1 has been described as an example. However, the present invention is not limited to this. For example, the present invention may be applied to a pneumatic booster in which a housing defines a set of constant pressure chambers and a variable pressure chamber by a power piston.

  As a pneumatic booster based on the embodiments described above, for example, the following modes can be considered.

  As a first aspect, a housing composed of a plurality of shells, a diaphragm defining the inside of the housing into a constant pressure chamber and a variable pressure chamber, a power piston together with the diaphragm, and positioned on the constant pressure chamber side are located on the diaphragm. A piston member formed along the power piston, a valve body connected to the power piston and moving in the housing, an input rod having one end connected to a brake pedal and the other end extending into the valve body, and the valve A plunger disposed in the body and connected to the input rod; and the input rod moves the plunger to introduce a working gas into the variable pressure chamber to create a pressure difference between the constant pressure chamber and the variable pressure chamber. A valve means for generating, an output rod on which a thrust generated in the power piston by this pressure difference acts, In the pneumatic booster provided, the diaphragm is provided with a protruding portion that protrudes into the variable pressure chamber, and a space is formed between the protruding portion and the piston member. Pneumatic booster characterized by

  As a second aspect, in the first aspect, the housing is provided between the front shell, a rear shell connected to a rear end side of the front shell, and the front shell and the rear shell. A diaphragm that includes a front shell that defines the front chamber as a front constant pressure chamber and a front variable pressure chamber, and a rear constant pressure chamber that defines the rear chamber as a rear constant pressure chamber. A rear diaphragm defined in the rear variable chamber, and the piston member includes a front piston member formed along the front diaphragm and a rear piston member formed along the rear diaphragm. And the projecting portion of the diaphragm includes at least the rear diaphragm of the front diaphragm and the rear diaphragm. Pneumatic booster, characterized in that provided in the arm.

  As a third aspect, in the first and second aspects, the space portion is divided into a plurality of ribs extending from the protruding portion of the diaphragm toward the piston member. Force device.

  As a fourth aspect, in the third aspect, a pneumatic booster according to the third aspect, wherein the rib has a tip abutting against the piston member.

1 Pneumatic Booster 2 Housing 3 Front Shell 4 Rear Shell 5 Center Shell 6 Valve Body 6G Valve Seat (Valve Means)
8 Input rod 9 Poppet valve body (valve means)
14 Plunger 14A Contact part (valve means)
17 Output Rod 25 Front Power Piston 26 Front Diaphragm 27 Front Piston Member 28 Rear Power Piston 29 Rear Diaphragm 30 Projection 30B Space 31 Rib 31A Tip 32 Rear Piston Member A Front Chamber A1 Front Constant Pressure Chamber A2 Front Transformer Chamber B Rear room B1 Rear side constant pressure room B2 Rear side transformer room

Claims (4)

A housing consisting of a plurality of shells;
A diaphragm that defines a constant pressure chamber and a variable pressure chamber in the housing;
A piston member which is formed along the diaphragm and which is located on the constant pressure chamber side and constitutes a power piston together with the diaphragm;
A valve body connected to the power piston and moving in the housing;
An input rod having one end connected to the brake pedal and the other end extending into the valve body;
A plunger disposed within the valve body and coupled to the input rod;
Valve means for introducing a working gas into the variable pressure chamber by causing the input rod to move the plunger to generate a pressure difference between the constant pressure chamber and the variable pressure chamber;
In a pneumatic booster comprising an output rod on which thrust generated in the power piston acts due to this pressure difference,
The diaphragm is provided with a protruding portion that protrudes toward the variable pressure chamber,
A pneumatic booster characterized in that a space is formed between the protrusion and the piston member. The housing includes a front shell, a rear shell connected to a rear end side of the front shell, and a center shell that is provided between the front shell and the rear shell and defines the inside of the housing into a front chamber and a rear chamber. And consist of
The diaphragm is composed of a front diaphragm that defines the front chamber into a front constant pressure chamber and a front transformer chamber, and a rear diaphragm that defines the rear chamber into a rear constant pressure chamber and a rear transformer chamber,
The piston member is composed of a front piston member formed along the front diaphragm and a rear piston member formed along the rear diaphragm,
2. The pneumatic booster according to claim 1, wherein the protruding portion of the diaphragm is provided on at least the rear diaphragm of the front diaphragm and the rear diaphragm.   3. The pneumatic booster according to claim 1, wherein the space portion is divided into a plurality of ribs extending from the protruding portion of the diaphragm toward the piston member. 4.   The pneumatic booster according to claim 3, wherein a tip of the rib is in contact with the piston member.

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