JPH08188141A - Pneumadraulic booster - Google Patents

Abstract

PURPOSE: To enable a cost down by simplifying the constitution of a connection between a power piston and a push rod. CONSTITUTION: A power piston 22 of a power cylinder part 10 and a piston 30 of a hydraulic cylinder part 12 are connected with a push rod 26, and air pressure inputted to the side of this power cylinder part 10 is converted into fluid pressure, transmitting it to a wheel cylinder. A tubular is formed at the side of an atmospheric chamber 20 of the power piston 22, and an end part 26a of the push rod 26 is inserted into the inner part. Two interconnecting holes 22b and 26c piercing through the tubular part 22a and the tip part 26a in the diametral direction are formed, and a pin 33 is inserted into these holes, through which both are connected together. A retainer 34 is fitted in and around a portion where this pin 32 is inserted through, thereby performing a slip-stop of this pin 32. In addition, a plate part 34 annularly expanded is formed on the circumference of this retainer 34, holding down this plate part 34b by dint of a return spring 24 resetting the power piston 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic / hydraulic booster used in a brake system of an automobile.

[0002]

2. Description of the Related Art An example of a conventional pneumatic-hydraulic booster will be described with reference to FIG. This pneumatic / hydraulic booster includes a power cylinder section 10 and a hydraulic cylinder section 12, and converts air pressure input to the power cylinder section 12 into hydraulic pressure and outputs the hydraulic pressure from the hydraulic cylinder section 12. However, it is transmitted to a wheel cylinder (not shown).

The power cylinder portion 10 is fitted into a cylinder shell 14 so as to be movable back and forth in the cylinder shell 14, and communicates with the pressure chamber 18 into which compressed air is introduced and the atmosphere. A power piston 22 that is partitioned into the atmosphere chamber 20 that is present, a return spring 24 that returns the power piston 22 to the non-actuated position shown in FIG. 2, and a push rod 26 that has one end 26 a fixed to the center of the power piston 22. The power piston 22 is actuated by receiving compressed air sent from an air reservoir (not shown) in response to the instruction pressure from the air brake valve, and the push rod 26 fixed to the power piston 22 is shown in FIG. Move to the right of 2.

The hydraulic cylinder portion 12 includes a cylinder body 28 and the other end 26 of the push rod 26.
The hydraulic piston 30 is connected to the b side and moves back and forth in the cylinder body 28. The compressed air pressure generated in the power cylinder section 10 causes the hydraulic piston 30 to move through the push rod 26.
The hydraulic pressure generated by moving forward is transmitted to a wheel cylinder (not shown).

[0005]

In the conventional pneumatic-hydraulic booster having the above structure, the through hole 22a is formed at the center of the power piston 22 of the power cylinder section 10.
The power cylinder 22 and the push rod 26 are integrally fixed by screwing the nut 25 into the end portion 26a of the push rod 26 which is inserted into the through hole 22a and protrudes to the pressure chamber 18 side. There is. Since the two members 22 and 26 are fixed to each other by screw fastening as described above, there is a problem that the number of parts is large, and further processing such as thread cutting and rotation stop is required, resulting in high cost. In addition, since the push rod 26 penetrates the power piston 22 and projects to the pressure chamber 18 side into which the compressed air in the cylinder shell 14 is introduced, the overall length becomes long, and the push rod 26 is mounted when mounted on a motor vehicle. There was also the problem of limited space.

The present invention has been made to eliminate the above-mentioned drawbacks. By improving the structure of the connecting portion between the power piston and the push rod, the structure is simplified, the number of parts is reduced, and the cost is reduced. SUMMARY OF THE INVENTION It is an object of the present invention to provide a pneumatic booster capable of shortening the overall length of the apparatus and increasing the degree of freedom of attachment to a vehicle.

[0007]

SUMMARY OF THE INVENTION A pneumatic-hydraulic booster according to the present invention comprises a power piston fitted in a cylinder shell so as to move back and forth, a return spring for returning the power piston, and the power piston. A push rod having one end fixed to it and a hydraulic piston attached to the other end of the push rod to move back and forth in the cylinder body, and convert the compressed air pressure acting on the power piston into a hydraulic pressure. And a cylindrical portion is formed on the atmospheric pressure chamber side of the power piston, the end portion of the push rod is inserted into the cylindrical portion, and the cylindrical portion of these power pistons is inserted. And the end of the push rod form a through hole in the diametrical direction and insert the pin, so that the power piston and the push rod are Binds, and it is obtained by so as to fit the retainer around the portion where the pin is inserted.

[0008]

In the pneumatic / hydraulic booster having the above structure, a diametrical through hole is formed in the connecting portion between the power piston and the push rod, and after inserting the pin, the retainer is fitted around the hole. Since the power piston and the push rod can be connected with each other, the configuration is extremely simplified.

[0009]

The present invention will be described below with reference to the illustrated embodiments.
FIG. 1 is a vertical cross-sectional view of an air-hydraulic booster according to an embodiment of the present invention. The same or corresponding parts as those of the conventional air-hydraulic booster described above are designated by the same reference numerals. . This pneumatic booster includes a power cylinder section 10 and a hydraulic cylinder section 12, and the power cylinder section 10
The air pressure input to is converted into hydraulic pressure, output from the hydraulic cylinder section 12, and transmitted to a wheel cylinder (not shown).

The power cylinder portion 10 is fitted into a cylinder shell 14 so as to be movable back and forth in the cylinder shell 14, and inside thereof is a pressure chamber 18 on the input port 16 side and an atmosphere chamber 20 on the power cylinder 12 side. , A return spring 24 which is disposed in the atmosphere chamber 20 to return the power piston 22 to the inoperative position shown in the drawing, and a push rod 26 having a tip portion 26a fixed to the central portion of the power piston 22. The power piston 22 operates toward the right in FIG. 1 in response to the compressed air sent from an air reservoir (not shown) according to the instruction pressure from the air brake valve, and is fixed to the power piston 22. Figure 1 shows the push rod 26
To the right of.

The hydraulic cylinder portion 12 has an end plate 27 that covers the opening side of the cylinder shell 14.
And a hydraulic cylinder that is slidably fitted in the cylinder body 28 and is connected to the other end 26b (right end in FIG. 1) of the push rod to integrally move back and forth. It has a piston 30 and
The power piston 22 in the power cylinder section 10 is
When moved by the compressed air introduced into the pressure chamber 18, the movement is transmitted to the hydraulic piston 30 via the push rod 26, pressurizing the brake fluid in the cylinder body 28 and transmitting it to the wheel cylinder. .

A cylindrical portion 22b is formed so as to project at the center of the surface of the power piston 22 on the atmosphere chamber 20 side, and a connecting hole 22c penetrating in the diameter direction is provided in this cylindrical portion 22b. ing. On the other hand, this power piston 2
The push rod 26 fixed to 2 has a tip portion 26a having a slightly smaller diameter, and is fitted into the cylindrical portion 22b of the power piston 22. A connecting hole 26C penetrating in the diametrical direction is also formed in the small-diameter tip portion 26a of the push rod 26, and the connecting hole 26C of the push rod 26 and the connecting hole 22c of the power piston 22 are aligned with each other. The tip portion 26a of the push rod 26 is fitted, and the connecting hole 22
Power pin 22 by inserting pin 32 into c and 26c
And the push rod 26 are integrally connected.

Power piston 22 and push rod 26
A retainer 34 having a cylindrical central portion 34a is fitted around the pin 32 connecting and fixing
2 is held. Further, an annular plate portion 34b extending toward the outer peripheral side is integrally provided at an end portion of the cylindrical portion 34a of the retainer 34 on the power piston 22 side. The outer peripheral edge portion 34c of the annular plate portion 34b is bent toward the atmosphere chamber 20, and an annular spring seat is formed near the inner periphery of the outer peripheral edge portion 34c. The return spring 24 is provided in the annular spring seat.
The end portion 24a on the side of the power piston 22 comes into contact with the power piston 22, and the retainer 34 is pressed against the power piston 22 so that the retainer 34 is fixed so as not to move.

Power piston 22 and push rod 26
The structure of the connecting portion with the power piston 22
The tip portion 26a of the push rod 26 is inserted into the cylindrical portion 22b formed in the above, and the pin 32 is inserted into the diametrical connecting holes 22c and 26c formed in the two 22b and 26a, respectively. Since the retainer 34 is fitted to the outer periphery of the inserted portion to prevent the pin 32 from being pulled out, the structure is simplified, and the number of parts can be reduced and the cost can be reduced. it can. Further, the simple structure allows easy disassembly and assembly. In addition, the power piston 22
Since the cylindrical portion 22b protruding above the surface of the atmosphere chamber 20 side is provided and the distal end portion 26a of the push rod 26 is inserted into the cylindrical portion 22b, the distal end portion of the push rod 26 as in the conventional configuration. The total length can be shortened as compared with a structure in which 26a penetrates the inside of the power piston 22 and projects toward the pressure chamber 18 side.

The power piston 22 that moves forward and backward while maintaining airtightness inside the cylinder shell 14 of the power cylinder 10 is usually made of metal.
A low friction bearing (wear ring) such as Teflon was attached to the outer peripheral part that slides on the inner peripheral surface of the to ensure smooth sliding. For example, the power piston itself is made of a resin molded product. By doing so, the slidability of the outer peripheral surface improves,
Since no wear ring is required, the cost can be reduced. Further, in this case, it is possible to obtain an effect that the sound at the time of operation becomes quiet. Further, by processing the connection hole 22c of the tubular portion 22b during molding, the pin 32 can be placed inside the tip end surface of the tubular portion 22b by the dimension A in FIG. 1, so that the total length can be shortened. The effect can also be obtained.

[0016]

As described above, according to the present invention, the power piston fitted in the cylinder shell so as to move back and forth, the return spring for returning the power piston, and the one end fixed to the power piston. Equipped with a push rod and a hydraulic piston attached to the other end of the push rod to move back and forth in the cylinder body. Compressed air pressure acting on the power piston is converted into hydraulic pressure and transmitted to the wheel cylinder. In the pneumatic hydraulic booster, a cylindrical portion is formed on the atmospheric pressure chamber side of the power piston, the end portion of the push rod is inserted into the cylindrical portion, and the cylindrical portion and the push portion of the power piston are pushed. The power piston and push rod are integrated by forming a diametrical through hole at the end of the rod and inserting the pin. The retainer is fitted around the part where the pin is inserted and the retainer is fitted so that the structure is simple and the number of parts is reduced to reduce the cost. Can be achieved. In addition, disassembly and assembly are facilitated. Further, the length of the entire device can be shortened.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a pneumatic-hydraulic booster according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view showing an example of a conventional pneumatic booster.

[Explanation of symbols]

 14 Cylinder Shell 18 Atmosphere Chamber 22 Power Piston 22b Cylindrical Portion of Power Piston 22c Cylindrical Portion Connection Hole 24 Return Spring 26 Push Rod 26a Push Rod Tip 26b Push Rod Other End 26c Push Rod Connection Hole 30 High Drolic piston 32 pin 34 retainer

Claims (2)

[Claims] 1. A power piston fitted in a cylinder shell so as to move back and forth, a return spring for returning the power piston, a push rod having one end fixed to the power piston, and a push rod other than the push rod. In the pneumatic-hydraulic booster, which has a hydraulic piston attached to an end to move back and forth in the cylinder body, converts compressed air pressure acting on the power piston into hydraulic pressure and transmits the hydraulic pressure to the wheel cylinder. A cylindrical portion is formed on the atmospheric pressure chamber side of the piston, and the end portion of the push rod is inserted into the cylindrical portion, and the cylindrical portion of the power piston and the end portion of the push rod are diametrically penetrated. By forming a hole and inserting the pin, the power piston and push rod are integrally connected, and the pin is inserted. A pneumatic-hydraulic booster characterized in that a retainer is fitted around the portion where the pin is retained to prevent the pin from coming off. 2. An annular plate portion is formed by extending an outer periphery of a portion of the retainer fitted to a cylindrical portion of the power piston, and the return spring is pressed against the annular plate portion to hold the annular plate portion. The pneumatic booster according to claim 1, wherein the retainer is fixed.