JP2004058959A - Pneumatic booster - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the initial responsiveness by allowing smooth flow-in of a working fluid in a plurality of working pressure chambers demarcated by a plurality of power pistons. <P>SOLUTION: In a tandem type pneumatic booster: a shell body 3 is demarcated in constant pressure chambers 9 and 10 and working pressure chambers 11 and 12 by two power pistons 7 and 8 having a center shell 4 and diaphragms 5 and 6; outside air is introduced into the rear working pressure chamber 12 through a first atmospheric passage 16 by the operation of a valve mechanism 22 in a valve body 13 common to the power pistons 7 and 8; the outside air is further introduced in the front working pressure chamber 11 through a second atmospheric passage 17 in a communicating tube 18 with a penetration rod 41 passed therethrough; the two power pistons 7 and 8 are propelled by the differential pressure between the constant pressure chambers 9 and 10; a rib 52 to limit diffusion of the outside air into the working pressure chamber 12 is integrated with a back side of the diaphragm 6 to demarcate the rear working pressure chamber 12; and flow-in of the outside air in the front working pressure chamber 11 is promoted in the initial operation. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pneumatic booster used for a brake system of a vehicle.
[0002]
[Prior art]
As a pneumatic booster, a plurality of power pistons with diaphragms that define a constant pressure chamber and an operating pressure chamber are arranged in the shell body, and pass through one operating pressure chamber defined by one power piston. And introducing a working fluid into another working pressure chamber defined by another power piston, and applying a pressure difference between each of the working pressure chambers and a constant pressure chamber corresponding to each of the working pressure chambers to the plurality of power pistons. Some have a structure that generates thrust. The pneumatic booster having two power pistons is particularly called a tandem type.
[0003]
[Problems to be solved by the invention]
However, according to this type of pneumatic booster, as described above, another working pressure chamber defined by another power piston passes through one working pressure chamber defined by one power piston. Since the structure is such that the working fluid is introduced into the working pressure chamber, the introduction of the working fluid into the other working pressure chamber is delayed more than the introduction of the working fluid into one working pressure chamber. There is a problem that thrust is not simultaneously generated in a plurality of power pistons at the beginning of the operation when the action is started, and the initial response is poor.
By the way, in this type of pneumatic booster, the shell main body is generally formed to have a larger diameter on the rear side than on the front side for convenience of arranging a plurality of power pistons in the axial direction and assembling them in the shell main body. Accordingly, the diameter of one power piston arranged on the rear side is larger than that of the other power piston arranged on the front side. This means that the volume of one working pressure chamber arranged on the rear side is larger than that of the other working pressure chambers arranged on the front side. The working fluid is easily diffused into the working pressure chamber, and a pressure difference is hardly generated before and after the power piston particularly at the beginning of the operation when the boosting action is started, which is a factor that further deteriorates the above initial response. I was
Further, as this type of pneumatic booster, stud bolts are integrally provided at both ends of a penetrating rod having a shell body penetrated in the axial direction, and the stud bolts are attached to the vehicle body and the booster is mounted. There is a so-called rod penetrating type which is commonly used for mounting the master cylinder to the above, but in this type, the power piston on the rear side cannot be formed along the shell body by the penetrating rod. The difference in volume of the working pressure chamber which has been further increased, which also contributed to the deterioration of the initial response.
The present invention has been made in view of the above-described conventional problems, and an object thereof is to enable smooth introduction of a working fluid to a plurality of working pressure chambers defined by a plurality of power pistons, Accordingly, it is an object of the present invention to provide a pneumatic booster which greatly contributes to improvement of initial response.
[0004]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a plurality of diaphragm-equipped power pistons that define a constant pressure chamber and an operating pressure chamber in a shell body, and one operating pressure defined by one power piston. A working fluid is introduced into another working pressure chamber defined by another power piston via the chamber, and the plurality of working fluids are introduced by a pressure difference between each working pressure chamber and a constant pressure chamber corresponding to each working pressure chamber. In a pneumatic booster for propelling a power piston, a limiter for limiting diffusion of a working fluid into the one working pressure chamber at an early stage of operation is provided in the one working pressure chamber.
In the pneumatic booster configured as described above, the restricting portion that restricts the diffusion of the working fluid into one working pressure chamber at the beginning of operation is provided, so that the working fluid can be introduced into another working pressure chamber. As a result, thrust is generated almost simultaneously in the plurality of power pistons, and the initial response is improved.
As described above, as the pneumatic booster, there is a pneumatic booster in which one working pressure chamber has a larger volume than the other working pressure chambers, or one in which the diameter of one power piston is larger than the other power pistons. The present invention is particularly useful when applied to such a booster, since a pressure difference easily occurs before and after another power piston, and the initial responsiveness is improved.
In the present invention, the limiting portion may be a rib protruding from a diaphragm of one power piston, or a rib protruding from a shell body defining one working pressure chamber, In either case, the number of parts and the number of assembling steps do not increase because they can be provided integrally when forming the diaphragm or the shell body.
[0005]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIGS. 1 to 3 show a pneumatic booster according to a first embodiment of the present invention. This pneumatic booster is configured as a tandem type, and as shown in FIG. 1, the inside of a shell body 3 composed of a front shell 1 and a rear shell 2 is divided into two front and rear chambers by a center shell 4. Each chamber partitioned by the center shell 4 is further partitioned into constant pressure chambers 9 and 10 and working pressure chambers 11 and 12 by power pistons 7 and 8 having diaphragms 5 and 6, respectively. , 8 have a common valve body 13 in which the center shell 4 and the rear shell 2 are airtightly and slidably inserted and the rear end of which extends to the outside of the shell body 3. The rear shell 2 has a small-diameter cylindrical portion 2a in which the valve body 13 is inserted. A dust boot 14 that covers a portion of the valve body 13 extending from the shell body 3 is formed in the small-diameter cylindrical portion 2a. It is installed.
[0006]
The valve body 13 has a cup-shaped main body portion 13a and a hollow shaft portion 13b connected to each other. The main body portion 13a serves as a sliding portion for the center shell 4, and the hollow shaft portion 13b slides on the rear shell 2. Each is used as a moving part. The main body 13a of the valve body 13 is provided with a negative pressure passage 15 that connects the two constant pressure chambers 9 and 10 to each other and connects the constant pressure chambers 9 and 10 to the inside of the hollow shaft portion 13b. A first atmospheric passage 16 is provided for communicating the inside of the shaft portion 13b with the rear working pressure chamber 12. Also, a plurality of (two in this case) communication pipes in the rear-side constant pressure chamber 10 that provide a second atmospheric passage 17 that connects the rear-side working pressure chamber 12 and the front-side working pressure chamber 11. 18 are provided. One end of the communication pipe 18 is press-fitted and fixed to the center shell 4, and the other end of the communication pipe 18 extends to a position close to the rear shell 2 through the rear power piston 8 in an airtight and slidable manner. Have been. On the other hand, for example, an engine negative pressure is introduced into the front-side constant pressure chamber 9 through a pipe joint 19 provided in the front shell 1, and the negative pressure is transmitted through the negative pressure passage 15 to the rear side. It is also supplied to the constant pressure chamber 10. Further, air is introduced into the hollow shaft portion 13b of the valve body 13 through a silencer 20 and a filter 21 fitted to the rear end of the hollow shaft portion 13b. Thus, the pressure is supplied to the front and rear working pressure chambers 11 and 12 through the first and second atmosphere passages 16 and 17.
[0007]
As shown in FIG. 2, the valve mechanism 22 is slidably fitted in a shaft hole 23 provided in the main body 13 a of the valve body 13 and has an input rod 24 which is interlocked with a brake pedal (not shown). The connected valve plunger 25, the poppet valve 27 whose base end is fixed to the inner surface of the hollow shaft portion 13b of the valve body 13 by the pressing member 26, the outer peripheral edge of the tip of the poppet valve 27 and the inner periphery of the valve body 13. A vacuum valve 29 composed of an annular valve seat 28 formed on the surface, an atmospheric valve 31 composed of an inner peripheral edge at the tip of the poppet valve 27 and an annular valve seat 30 formed at the rear end of the valve plunger 25. And a valve spring 32 having one end locked to the input rod 24 and constantly biasing the poppet valve 27 in the valve closing direction. Further, a return spring 33 is interposed between the pressing member 26 and the input rod 24, and when the valve plunger 25 is not operated with no input from the brake pedal, the return spring 33 allows the valve plunger 25 to move its rear end. The state where the annular valve seat 30 is in contact with the poppet valve 27 is maintained.
[0008]
In the shaft hole 23 of the valve body 13, a stepped moving body 34 whose rear end is connected to the valve plunger 25 and moves integrally with the plunger 25 is housed. The movable body 34 has a small-diameter portion 34 a on the tip end side slidably inserted into the small-diameter hole 23 a of the shaft hole 23. A reaction disk 35 made of an elastic material such as rubber and a base cup portion 36a of an output rod 36 are arranged on the bottom of the cup of the main body 13a of the valve body 13, and the moving body 34 It can be abutted on the back. The distal end of the output rod 36 extends airtightly and slidably through the bottom of a recess 1a provided on the front surface of the front shell 1 and extends forward, and is connected to the recess 1a. The master cylinder (not shown) is operatively connected.
[0009]
Further, a return spring 37 for returning the valve body 13 to the original position is provided in the constant pressure chamber 9 on the front side. The return spring 37 is disposed such that one end thereof is in contact with the rear portion of the concave portion 1a of the front shell 1 and the other end is in contact with the cup bottom of the valve body 13 via a spring receiver 38, respectively. The return spring 37 normally urges the rear side (return direction). The original position of the valve body 13 is such that the stop key 39 inserted from the radial direction at a substantially boundary portion between the main body portion 13a and the hollow shaft portion 13b abuts on the step portion 40 provided on the small-diameter cylindrical portion 2a of the rear shell 2. It has become. On the other hand, the tip of the stop key 39 is engaged in a groove provided in the valve plunger 25, and the relative movement range of the valve plunger 25 with respect to the valve body 13 is regulated by the stop key 39. . The spring receiver 38 is also used as a stopper for the reaction disk 35 and the output rod 36.
[0010]
In the present embodiment, as shown in FIG. 1, the front shell 1 and the rear shell 2 are hermetically sealed in each communication pipe 18 that communicates the rear working pressure chamber 12 and the front working pressure chamber 11. And a penetrating rod 41 extending through the front power piston 7 in an airtight manner is inserted. Stud bolts 42, 43 are integrally provided at both ends of the through rod 41, and these stud bolts 42, 43 are arranged upright on the rear surface of the rear shell 2 and the front surface of the front shell 1. Here, the penetration rod 41 is provided at the base end of the stud bolt 43 on the front side while the flange 44 provided on the base end of the stud bolt 42 on the rear side is in contact with the inner surface of the rear shell 2. The stopper plate 45 engaged with the step portion 41 a is elastically brought into contact with the inner surface of the front shell 1, whereby the position is fixed between the rear shell 2 and the front shell 1. The through rod 41, that is, two stud bolts 42, 43 are provided at 180-degree intervals in the circumferential direction, but the rear shell 2 and the front shell 1 have a 90-degree phase with the stud bolts 42, 43. In a different mode, two general-purpose stud bolts (not shown) are planted.
[0011]
Here, the front shell 1 constituting the shell main body 3 has a cylindrical portion 46 extending greatly toward the rear side, and the center shell 4 has a cylindrical portion 47 extending relatively greatly toward the rear side. The parts 46 and 47 are caulked and fixed to the rear shell 2 in a state where they are combined. In the front-side power piston 7, the outer peripheral bead portion 5a of the diaphragm frame 5 is located between a shoulder provided at an intermediate portion of the cylindrical portion 46 of the front shell 1 and a shoulder portion of the center shell 24. Accordingly, the power piston 8 on the rear side is fixed to the shell main body 23 by positioning the outer peripheral bead portion 6a of the diaphragm frame 6 in the caulking fixing portion. The cylindrical portion 46 of the front shell 1 is formed in a frusto-conical shape whose diameter gradually increases toward the mating side with the rear shell 2 in consideration of the assemblability of the center shell 4 and the front power piston 7. . Therefore, the diameter of the rear-side power piston (one power piston) 8 is larger than the diameter of the front-side power piston (other power piston) 7, and accordingly, the front-side working pressure chamber (other working pressure) The working pressure chamber (one working pressure chamber) 12 on the rear side of the chamber (chamber) 11 has a larger volume.
[0012]
On the other hand, the diaphragm 6 constituting the rear power piston 8 has a tube insertion hole 51 for inserting the communication tube 18 around a fitting hole 50 for the valve body 13 as well shown in FIG. Two are provided at 180 degree intervals. An elliptical rib 52 projects from the rear surface of the diaphragm 6 so as to surround the outside of the two tube insertion holes 51. The height of the rib 52 is set so as to leave a slight gap between the rib 52 and the inner surface of the rear shell 2 when the booster is not operated. The diffusion of the atmosphere into the side working pressure chamber 12 is restricted. Therefore, the ribs 52 constitute a restricting portion that restricts the diffusion of the working fluid into the rear-side working pressure chamber 12 at the beginning of the operation. Since the diaphragm 6 constituting the rear power piston 8 needs to form a sliding portion 53 for the communication tube 18 at the edge of the tube insertion hole 51, the diaphragm 6 can be formed along the rear shell 2. However, the volume of the rear-side working pressure chamber 12 has been increased accordingly.
[0013]
Hereinafter, the operation of the pneumatic booster according to the first embodiment will be described.
The pneumatic booster is attached to the vehicle body using a stud bolt 42 at one end of the through rod 41 and a general-purpose stud bolt (not shown), and a stud bolt 43 at the other end of the through rod 41 and The master cylinder is connected to the booster using a general-purpose stud bolt. At this time, since both stud bolts 42 and 43 have high rigidity integrally with the penetrating rod 41, the booster is firmly attached to the vehicle body, and furthermore, the master cylinder is controlled by the booster. Support is also stable.
[0014]
When the brake pedal is depressed in the mounted state, the input rod 24 advances, the valve plunger 25 advances, and the air valve seat 30 at the rear end of the valve plunger 25 separates from the poppet valve 27 to release the air valve. 31 opens. Thereby, the air flows into the hollow shaft portion 13b of the valve body 13 through the silencer 20 and the filter 21, and the air is introduced into the rear-side working pressure chamber 12 through the first air passage 16. At this time, since the rib 52 provided on the diaphragm frame 6 protrudes into the rear-side working pressure chamber 12, the diffusion of the atmosphere to the outer peripheral edge side in the working pressure chamber 12 is restricted by the rib 52, Thereby, the atmosphere is smoothly supplied to the front-side working pressure chamber 11 through the second atmosphere passage 17 in the communication pipe 18. As a result, a pressure difference is quickly generated between the front / rear working pressure chambers 11 and 12 and the front / rear constant pressure chambers 11 and 12 where the negative pressure is introduced. The power pistons 7, 8 are propelled, and the thrust is output from the valve body 13 to the master cylinder via the output rod 36, and the boosting action is started. That is, the braking force is generated almost simultaneously with the depression of the brake pedal, and the initial response is sufficient.
In the present embodiment, in particular, the working pressure chamber 11 on the front side has a smaller volume than the working pressure chamber 12 on the rear side. A pressure difference is quickly generated between the working pressure chamber 11 and the constant pressure chamber 9, and the above-described initial response is further improved.
[0015]
After the start of the above-described boosting action, the rib 52 provided on the diaphragm frame 6 of the rear power piston 8 is separated from the rear shell 2, so that the atmosphere quickly flows around the entire rear-side working pressure chamber 12, As a result, a desired boosting action in which the output increases with an increase in the input is performed. In this boosting operation, the output reaction force is transmitted from the reaction disk 35 to the input rod 24 via the moving body 34 and the valve plunger 25.
[0016]
On the other hand, when the pedaling force on the brake pedal is released, the input rod 24 is retracted by the spring force of the return spring 33, and the valve plunger 25 is also retracted, whereby the air valve seat 30 at the rear end of the valve plunger 25 is moved. While the atmosphere valve 31 is closed by contacting the poppet valve 27, the poppet valve 27 is lifted by the valve plunger 25 to open the negative pressure valve 29, and the negative pressure passage 15 and the second Negative pressure is introduced through the first and second atmosphere passages 16 and 17, and the above-mentioned pressure difference is eliminated. Thereafter, the valve body 13 retreats due to the spring force of the return spring 37 in the front-side negative pressure chamber 9, and the valve body 13 returns to the original position where the stop key 39 contacts the step portion 40 in the rear shell 2, At the same time, the valve plunger 25 returns to the original position, and the negative pressure valve 29 is closed.
[0017]
4 and 5 show a tandem-type pneumatic booster according to a second embodiment of the present invention. Since the basic structure of the tandem type pneumatic booster is the same as that of the first embodiment, only the main parts are shown here, and the same parts as those shown in FIGS. The same reference numerals are given and duplicate description will be omitted.
A feature of the second embodiment is that a limiting portion for limiting the diffusion of the atmosphere to the rear-side working pressure chamber 12 at the beginning of the operation is provided by the rear-side diaphragm frame 6 in the first embodiment. Instead of the rib 52 provided on the rear shell 2, a rib 60 protruding toward the working pressure chamber 12 is integrally formed on the rear shell 2. The rear shell 2 includes two bolt insertion holes 61 for inserting a stud bolt 42 integrated with the through rod 41 around the small diameter cylindrical portion 2a through which the hollow shaft portion 13b of the valve body 13 is inserted, and the general-purpose stud bolt. And two bolt insertion holes 62 through which the bolts are inserted are provided alternately at 90-degree intervals. Here, the rib 60 is extended symmetrically in the axial direction along the small-diameter cylindrical portion 2a, and includes a pair of rib pieces 60a and 60b whose both ends are located near the bolt insertion hole 61. I have.
[0018]
The operation of the pneumatic booster according to the second embodiment is the same as that of the first embodiment, and the atmosphere valve 31 is opened in response to the depression of the brake pedal, and the atmosphere is released from the first atmosphere passage 16. And is introduced into the working pressure chamber 12 on the rear side. At this time, since a pair of rib pieces 60a, 60b (ribs 60) provided on the rear shell 2 protrude into the rear-side working pressure chamber 12, the air flowing into the working pressure chamber 12 is removed by the pair. The rib pieces 60a and 60b restrict diffusion to the outer peripheral edge side, and are guided to the communication pipe 18 side aligned with the two bolt insertion holes 61, and are passed through the second air passage 17 in the communication pipe 18 to the front side. Is supplied smoothly to the working pressure chamber 11 of the first embodiment. Therefore, as in the first embodiment, a pressure difference is quickly generated between the front and rear working pressure chambers 11 and 12 and the front and rear constant pressure chambers 11 and 12, and the initial responsiveness is sufficient. It becomes.
[0019]
【The invention's effect】
As described above, according to the pneumatic booster according to the present invention, since the diffusion of the working fluid into one working pressure chamber is limited by the restriction part at the beginning of the operation, the working fluid to the other working pressure chamber is restricted. Is promoted, and thrust is generated almost simultaneously at a plurality of power pistons, thereby greatly improving the responsiveness at the beginning of operation.
In particular, when applied to a booster in which the volume of one working pressure chamber is larger than that of another working pressure chamber, or a booster in which the diameter of one power piston is larger than the other working pistons, Since the circulation of the working fluid to the pressure chamber is further promoted, a pressure difference is easily generated before and after the power piston, and the initial response is further improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing the entire structure of a pneumatic booster according to a first embodiment of the present invention.
FIG. 2 is an enlarged sectional view showing a main part of the pneumatic booster shown in FIG.
FIG. 3 is a plan view showing the shape of a rear diaphragm used in the pneumatic booster shown in FIG. 1;
FIG. 4 is a cross-sectional view showing the entire structure of a pneumatic booster according to a second embodiment of the present invention.
5 is a plan view showing the shape of a rear shell used in the pneumatic booster shown in FIG.
[Explanation of symbols]
Reference Signs List 1 front shell 2 rear shell 3 shell body 4 center shell 5, 6 diaphragm 7 front side power piston (other power piston)
8. Rear power piston (one power piston)
9, 10 Constant pressure chamber 11 Front side working pressure chamber (other working pressure chamber)
12. Rear working pressure chamber (one working pressure chamber)
13 Valve Body 22 Valve Mechanism 24 Input Rod 36 Output Rod 41 Through Rod 52 Rib Protruding from Diaphragm 60 Rib Protruding from Rear Shell

Claims (5)

A plurality of power pistons with a diaphragm that define a constant pressure chamber and a working pressure chamber are arranged in the shell body, and are defined by another power piston via one working pressure chamber defined by one power piston. A pneumatic booster for introducing a working fluid into another formed working pressure chamber and generating a thrust on the plurality of power pistons by a pressure difference between each of the working pressure chambers and a constant pressure chamber corresponding to each of the working pressure chambers. A pneumatic booster, wherein a limiter is provided in the one working pressure chamber to limit diffusion of a working fluid into the one working pressure chamber at an early stage of operation. The pneumatic booster according to claim 1, wherein the capacity of one working pressure chamber is larger than that of the other working pressure chambers. The pneumatic booster according to claim 1, wherein the diameter of one power piston is larger than that of the other power pistons. The pneumatic booster according to any one of claims 1 to 3, wherein the limiting portion is a rib protruding from a diaphragm of one power piston. The pneumatic booster according to any one of claims 1 to 3, wherein the restricting portion is a rib protruding from a shell body defining one working pressure chamber.

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