JPH07257355A - Master cylinder - Google Patents

Abstract

PURPOSE:To prevent the pressure in a pressure chamber from being leaked to a supply chamber and reduce the cost by providing a seal member having a first seal surface making contact with the outer circumferential surface of a valve seat member, a second seal surface making contact with the end surface of a piston, and a third seal surface making contact with the inner surface of a cylinder hole. CONSTITUTION:When a left pressing force is added to a piston 12, the piston 12 is moved to the left against the energizing force of a return spring 13, a valve seat part 23a makes contact with a valve body 22 to interrupt a communicating passage 18, and the pressure of the operating liquid in a pressure chamber R2 is raised in proportion to the pressing force added to the piston 12. In this case, since the sealings between the seat valve member 23 and the piston 12 and between a cylinder hole 11a and the piston 12 are simultaneously performed, the sealing between the pressure chamber R2 and a supply chamber R1 can be performed by one seat member 26. Since the piston 12 needs not to be integrated into the valve seat member 23 by press-fitting, no high dimensional precision is required.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a master cylinder.

[0002]

2. Description of the Related Art As a conventional master cylinder, firstly, the technology disclosed in Japanese Utility Model Laid-Open No. 1-171769 is known. FIG. 3 is a partially enlarged cross-sectional view around the valve mechanism of the above-mentioned first conventional master cylinder, and as shown in FIG.
Is a replenishment chamber that is fluid-tightly and axially inserted into the cylinder hole 101a of the cylinder body 101 through the piston cup 102 and is in constant communication with the cylinder hole 101a and the reservoir 104. 105 and a piston 107 having a communication hole 106 for communicating the pressure chamber 103 with the replenishment chamber 105, and the pressure chamber 103.
A return spring 108 which is disposed inside and urges the piston 107 toward the non-actuating position, and the pressure chamber 10 through the communication hole 106 when the piston 107 is in the non-actuating position.
3 is provided with a valve mechanism v that allows communication between the pressure chamber 103 and the replenishment chamber 105 by closing the communication hole 106 when the piston 107 moves a set amount from the inoperative position. .

The piston 107 has a center pin 1 in the radial direction.
09 is inserted, and both ends of the center pin 109 are supported by an outer peripheral member 110 fitted on the outer periphery of the piston 107. The center pin 109 is in contact with the valve element 111 and separates the valve element 111 from the valve seat portion 113 against the biasing force of the spring 112. Peripheral member 110
An O-ring 114 for sealing is arranged on the inner peripheral surface into which the piston 107 is inserted, and a seal cup 116 that seals with the cylinder hole 101a is fitted on the outer peripheral surface.

In the first prior art, when the piston 107 is pressed to the left in the drawing, the piston 107 moves against the urging force of the return spring 108, and the valve element 111 is seated. It contacts the part 113. As a result, the pressure chamber 103 is sealed by the piston 107, the seal cup 115, and the valve mechanism v, and the piston 10
When a pressing force is further applied to 7, the hydraulic fluid in the pressure chamber is boosted.

Secondly, the technique disclosed in Japanese Utility Model Publication No. 3-122974 is known. FIG. 4 is a partially enlarged cross-sectional view around the valve mechanism of the master cylinder of the second related art described above. As shown in FIG. 4, the master cylinder 200 of this technology is similar to the first related art. A piston 2 having a communication hole 204 that forms a pressure chamber 202 and a replenishment chamber 203 in the cylinder hole 201a and connects both chambers.
05, a return spring 206 that urges the piston 205 toward the non-operating position, and a valve mechanism v that connects and disconnects the communication hole 204.

The piston 205 includes the first and second members 20.
5a, 205b, the first member 205a
Is press-fitted into the second member 205b so as to slide integrally within the cylinder hole 201a. or,
On the inner circumference of the second member 205b, a valve body 207 constituting the valve mechanism v is slidable in the axial direction and a spring 208 is provided.
Is provided while being urged to the right in the figure by the valve mechanism 207.
When the pressure is shut off, the pressure in the pressure chamber 202 is
An elastic body 207a is fitted so as not to escape to the 3 side.

In the second prior art, when a biasing force is applied to the piston 205 to the left in the drawing to move the piston 205, the spring 208 acts to cause the valve element 207 to move.
Moves to the right in the figure relative to the piston 205,
When the valve body 207 contacts the end surface of the first member 205a of the piston, the communication hole 204 is blocked, the pressure chamber 202 is sealed, and the hydraulic fluid in the pressure chamber 202 is pressurized.

[0008]

In the first prior art, an O-ring 114 for sealing provided between the piston 107 and the outer peripheral member 110 and a piston cup 115.
Is configured to prevent the hydraulic pressure in the pressure chamber 103 from leaking to the supply chamber 105 side, and two seal members are required to prevent the pressure in the pressure chamber from leaking to the supply chamber side. High cost.

In the second prior art, the piston 20
The first member 205a of No. 5 is press-fitted into the second member 205b to prevent the pressure in the pressure chamber 202 from leaking to the supply chamber 203 side, but the press-fitting portion is required to have a high dimensional accuracy. Therefore, the cost was high.

An object of the present invention is to provide a low cost master cylinder which can prevent the pressure in the pressure chamber from leaking to the replenishing chamber with one sealing member and which does not require a high dimensional accuracy.

[0011]

The technical means taken in the present invention to solve the above-mentioned technical problem is to provide a liquid-tight and axial shaft via a piston cup in a cylinder hole of a cylinder body for containing a hydraulic fluid. Piston that is slidably inserted in the direction to form a pressure chamber that is in constant communication with the hydraulic line in the cylinder hole and a replenishment chamber that is in constant communication with the reservoir, and that has a communication hole that communicates between the pressure chamber and the replenishment chamber. A return spring housed in the pressure chamber for urging the piston toward the non-actuated position, a valve seat member mounted at the tip of the piston and having a communication hole formed therein, and along with the actuation of the piston. A valve seat that separates from and contacts the valve seat member, communicates with the communication hole when the piston is in the non-actuated position, and shuts off the communication hole when the piston moves from the non-actuated position by a predetermined amount or more. In the master cylinder, a seal member having a first seal surface that contacts the outer peripheral surface of the valve seat member, an annular second seal surface that contacts the end surface of the piston, and a third seal surface that contacts the inner surface of the cylinder hole. It was equipped with.

Preferably, an elastic O-ring is provided in the mounting portion of the piston and the valve seat member.

[0013]

In the present invention, since the seal member simultaneously seals between the valve seat member and the piston and between the cylinder hole and the piston, the pressure chamber and the replenishing chamber can be sealed by one member. It is low cost. or,
Since it is not necessary to integrate the piston and the valve seat member by press fitting, a high dimensional accuracy is not required and the cost is low.

Further, since the elastic O-ring is interposed between the mounting portion of the piston and the valve seat member, the valve seat member is prevented from engaging with the piston and coming off from the piston. At the same time, the assembly can be easily performed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described with reference to the drawings.

FIG. 1 is a partial sectional view of a tandem master cylinder of this embodiment. In the figure, the master cylinder 10 is a cylinder hole 1 formed in a cylinder body 11.
Two hydraulic pressure generators of a portless type and a portless type or a conventional type are arranged in 1a in series in the axial direction.

The hydraulic pressure generator comprises a piston 12, a return spring 13, first and second retainers 14 and 15, a valve mechanism V and the like.

The piston 12 is fluid-tightly and axially slidably fitted into the cylinder hole 11a through a piston cup 17 fitted to the outer circumference. Also, the piston 12 is
A cylinder chamber 11 and a supply chamber R1 that is in constant communication with a brake reservoir (not shown) through a supply port 11b formed in the cylinder body 11 in the cylinder hole 11a.
An axial communication passage 18 and a radial communication passage 19 are formed which are partitioned into a pressure chamber R2 which is always in communication with a hydraulic pressure pipe (not shown) through an outlet port 11c formed in the above. .

At the tip of the piston 12, a valve seat member 23 is provided with an internal space 24 through an elastic O-ring 16.
Are engaged while forming. In this internal space 24,
A diaphragm forming member 20 having a diaphragm passage 20a (FIG. 2) formed in the center is interposed with a sufficient gap.

The first retainer 14 is fitted on the valve seat member 23, and urges one end of the return spring 13 and a valve body 22 described later toward the valve seat member 23.
1 and one end are held. The second retainer 15 is fitted to the piston 25 used in the other hydraulic pressure generator, and holds the other end of the return spring 13.

The valve mechanism V includes a valve body 22 and a valve seat member 23.
Etc. The valve body 22 can contact the valve seat portion 23a of the valve seat member 23 by the valve body portion 22a to shut off the supply chamber R1 and the pressure chamber R2, while the engaging portion 22b engages with the second retainer 15. Is integrally formed via the rod portion 22c, and the movement amount of the valve body 22 is restricted.

A seal member 26 is fitted on the outer periphery of the valve seat member 23, and the inner peripheral surface (first seal surface 26a) of the seal member 26 is in contact with the valve seat member 23. Seal member 26
In the drawing, the right surface (second sealing surface 26b) is the end surface of the piston 12, and the outer peripheral surface (third sealing surface 26c) is the cylinder hole 1
The valve seat member 23 and the piston 12 and the cylinder hole 11a and the piston 12 are sealed by making contact with 1a. The valve seat portion 23a has a metal ring 23a ′ located on the inner peripheral side.
And a rubber ring 23a ′ located on the outer peripheral side,
It is fitted to the valve seat member 23.

Next, the operation of this embodiment will be described.

When a pressing force is applied to the piston 12 to the left in the drawing, the piston 12 moves to the left in the drawing against the urging force of the return spring 13, and the valve seat portion 23a and the valve body 22 are moved.
And the contact passage 18 are cut off, the piston 1
The hydraulic fluid in the pressure chamber R2 is pressurized in proportion to the pressing force applied to the pressure chamber R2.

When the pressing force on the piston 12 is released,
The urging force of the return spring 13 causes the piston 12
Is moved back. At this time, the valve body 22 moves to the right in the drawing while abutting the valve seat portion 23a as the piston 12 returns due to the urging force of the spring 21 (FIG. 2), and the engagement portion 22b of the valve body moves. When the piston 12 is engaged with the second retainer 15 and returns to its original position, the valve body 22 and the valve seat portion 23a are separated from each other, and communication between the pressure chamber R2 and the replenishment chamber R1 is established and the pressure chamber R2 is established. The hydraulic fluid inside is depressurized.

In this embodiment, the seal member 26 is provided between the valve seat member 23 and the piston 12 and the cylinder hole 11a.
Since the seal between the piston 12 and the piston 12 is performed at the same time, the pressure chamber R2 and the replenishment chamber R3 can be sealed with one member, which is low cost.

Further, since it is not necessary to integrate the piston 12 and the valve seat member 23 by press fitting, a high dimensional accuracy is not required and the cost is low.

Further, the abutment portion 27 of the axial end surfaces of the piston 12 and the valve seat member 23 and the pressure chamber R2 are increased in pressure, so that the seal member 26 is prevented from being galled.

Further, since the elastic O-ring 16 is interposed between the piston 12 and the mounting portion of the valve seat member 23,
The valve seat member 23 is engaged with the piston 12 so that the valve seat member 23
Is prevented from falling out of the piston 12.

Further, the seal member 26 allows the piston 1
In order to seal the space between the valve 2 and the valve seat member 23, the O-ring 16 is configured so that the pressure in the pressure chamber R2 does not depend on the O-ring 16.
It is possible to prevent kinking of the ring 16.

Although the present invention is applied to the tandem master cylinder in the above-mentioned embodiment, the present invention is not limited to this and a single master cylinder may be used.

[0032]

According to the first aspect of the present invention, since the seal between the valve seat member and the piston and between the cylinder hole and the piston is performed at the same time by the seal member, the pressure chamber and the replenishing chamber are sealed together by one seal. It can be performed by a member and is low cost. Further, since it is not necessary to integrate the piston and the valve seat member by press fitting, a high dimensional accuracy is not required and the cost is low.

According to the second aspect of the present invention, since the elastic O-ring is interposed between the mounting portion of the piston and the valve seat member, the valve seat member is engaged with the piston and the valve seat member is removed from the piston. It is prevented from falling off.

[Brief description of drawings]

FIG. 1 shows a partial sectional view of a master cylinder according to the present invention.

FIG. 2 is a partially enlarged cross-sectional view around a valve mechanism of a master cylinder according to the present invention.

FIG. 3 is a partially enlarged cross-sectional view around a valve mechanism of a master cylinder disclosed in the first related art.

FIG. 4 is a partially enlarged cross-sectional view around a valve mechanism of a master cylinder disclosed in a second conventional technique.

[Explanation of symbols]

 10 ... Master cylinder 11a ... Cylinder hole 12 ... Piston 13 ... Return spring 16 ... O-ring 17 ... Piston cup 18 ... Communication hole 22 ... Valve body 23 ...・ Valve seat member 23a ... Valve seat portion 26 ... Seal member 26a ... First seal surface 26b ... Second seal surface 26c ... Third seal surface R1 ... Replenishment chamber R2 ...・ Pressure chamber V ・ ・ ・ Valve mechanism

Claims (2)

[Claims] 1. A pressure which is fluid-tightly and axially slidably inserted into a cylinder hole of a cylinder body containing a hydraulic fluid so as to be slidable in the axial direction, and which is constantly communicated with a hydraulic line in the cylinder hole. A piston having a communication hole that forms a replenishment chamber that always communicates with the chamber and the reservoir and that communicates the pressure chamber with the replenishment chamber; and a piston housed in the pressure chamber and biasing the piston toward a non-operating position. A return spring, a valve seat member that is attached to the tip of the piston and in which the communication hole is formed, and a valve body that separates from and contacts the valve seat member in accordance with the operation of the piston, In a master cylinder including a valve mechanism that communicates the communication hole when the piston is in the non-operating position, and shuts off the communication hole when the piston moves from the non-operating position by a predetermined amount or more, A seal member having a first seal surface contacting the outer peripheral surface of the valve seat member, an annular second seal surface contacting the end surface of the piston, and a third seal surface contacting the inner surface of the cylinder hole; A master cylinder characterized by that. 2. The master cylinder according to claim 1, further comprising an elastic O-ring interposed between mounting portions of the piston and the valve seat member.