JPH05178197A - Master cylinder - Google Patents

Abstract

PURPOSE:To ensure sealing characteristic over the entire inner circumferential part of a cup seal, and to stabilize pressure receiving balance of the cup seal. CONSTITUTION:Taper parts 31, 32, the diameter of which are gradually narrowed as it goes to pressure chambers 6, 7, are formed on the outer peripheral parts of pistons 3, 4, on which cup seals 18, 20 are arranged, and the inner circumferential part of the cup seal is provided along the taper part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a master cylinder used for a brake device, a clutch device, etc. of a vehicle.

[0002]

2. Description of the Related Art Conventionally, as a technique of this kind, there is, for example, Japanese Patent Laid-Open No. 63-145158, which discloses that a hollow cylinder body and a pressure chamber are formed in the cylinder body. A piston slidably inserted in the
A replenishment chamber that communicates with a reservoir that is formed between the outer circumference of the piston and the cylinder body, a cup seal that is placed on the outer circumference of the piston and that seals liquid-tightly only from the pressure chamber to the replenishment chamber, and a cut seal of the piston are provided. A retainer for restricting a certain amount of movement of the cup seal to the pressure chamber side, which is arranged on the outer circumference on the pressure side of the portion to be installed, is provided.

[0003]

However, in the above-mentioned prior art, since the outer periphery of the piston in which the cup seal is arranged is formed in a shape along the axial direction of the piston, the tip of the inner peripheral portion of the cup seal is formed. Since the sealability with the piston is ensured, the tightness of the cup seal concentrates on the tip of the inner peripheral portion, which causes a problem of poor pressure receiving balance during operation.

Therefore, it is an object of the present invention to secure the sealability with the piston in the entire inner peripheral portion of the cup seal and to stabilize the pressure receiving balance.

[0005]

[Constitution of the invention]

[0006]

The technical means taken in the present invention to solve the above technical problems is to form a hollow cylinder body and a pressure chamber in the cylinder body. A piston that is slidably inserted, a replenishing chamber that communicates with a reservoir formed between the outer circumference of the piston and the cylinder body, and a liquid-tight seal only from the pressure chamber to the replenishing chamber that is arranged on the outer circumference of the piston. A cup seal that seals to
In a master cylinder provided with a retainer for restricting a certain amount of movement of the cup seal to the pressure chamber side, which is arranged on the outer periphery of the piston on the pressure chamber side of the portion where the cup seal is arranged, the piston cup seal is arranged. That is, a tapered portion whose diameter gradually decreases toward the pressure chamber is formed on the outer peripheral portion of the cup seal, and the inner peripheral portion of the cup seal has a shape along the tapered portion.

[0007]

The above technical means works as follows. A tapered portion is formed on the outer peripheral portion of the piston where the cup seal is arranged, the diameter of which gradually decreases toward the pressure chamber, and
Since the inner peripheral portion of the cup seal is formed along the taper portion, the entire inner peripheral portion of the cup seal secures the sealing property with the piston.

[0008]

Embodiments to which the present invention is applied will now be described in detail with reference to the accompanying drawings.

In FIG. 1, a master cylinder 1 is formed in a hollow cylindrical shape and has a cylinder body 2 having a left end in the figure closed and a right end in the figure open, and a first pressure chamber 6 in the cylinder body 2.
And a first piston 3 and a second piston 4 which partition the second pressure chamber 7 and are slidably fitted therein.

In the cylinder body 2, a reservoir tank (not shown) for storing hydraulic oil is connected at the upper part of the drawing by reservoir coupling portions 12 and 13, and the reservoir tank, the outer circumferences of both pistons 3 and 4, and the cylinder body. The first replenishment chamber 9 and the second replenishment chamber 10 respectively formed between the first replenishment chamber 9 and the second replenishment chamber 2 through the inner holes of the reservoir coupling ports 12 and 13 and the supply ports 21 and 22 formed on the peripheral wall of the cylinder body 2. It is in communication.

The first piston 3 is provided with a first retainer 15 at an end facing the second piston 4, and an end of the first retainer 15 and the second piston 4 facing the first piston 3. The first return spring 8a disposed between the first retainer 15 and the second retainer 16 disposed at the position shown in the figure when not in operation by the connect rod 17 penetrating the first retainer 15 and the second retainer 16. Retained. Further, from the first replenishing chamber 9 to the first pressure chamber 6, the first taper portion 31 is formed on the outer periphery of the first piston 3 on the first replenishing chamber 9 side of the portion where the first retainer 15 is arranged. Only the first cup seal 18 which allows the flow of hydraulic oil is mounted.

The first cup seal 18 is the first piston 3
When the pressing force is applied to the small hole 23,
The hydraulic oil in the pressure chamber 6 is prevented from entering the first replenishing chamber 9, and when the first piston 3 is pushed, the hydraulic oil in the first pressure chamber 6 is pressurized. The pressure oil is supplied to a brake cylinder (not shown) via a port 5 formed in the cylinder body 2.

The second piston 4 has a second retainer 16 arranged at the end facing the first piston 3, and a third retainer 19 arranged at the end facing the bottom of the cylinder body 2. There is. The second piston 4 is held at the illustrated position by the first return spring 8a and the second return spring 8b which are arranged between the second piston 4 and the bottom of the cylinder body 2 when the second piston 4 is not operated. In addition, the second replenishment chamber 10 is located closer to the second piston 4 than the portion where the third retainer 19 is disposed.
A second cup seal 20 that allows the working oil to flow only from the second supply chamber 10 to the second pressure chamber 7 is attached to the second taper portion 32 formed on the outer periphery of the side.

The second cup seal 20 includes the second piston 4
When the pressing force is applied to the
The hydraulic oil in the pressure chamber 7 is prevented from entering the second replenishment chamber 10, and when the second piston 3 is pushed by this, the hydraulic oil in the second pressure chamber 7 is pressurized. The pressure oil is supplied to a brake cylinder (not shown) via a port 11 formed in the cylinder body 2.

The operation of the first cup seal 18 will be described below with reference to FIGS. Since the second cup seal 20 is similar to the first cup seal 18, the description thereof will be omitted. In FIG. 2 showing the state in which the first cup seal 18 is not assembled to the first piston 3, the first cup seal 18 has an inner peripheral portion 18a with a tapered portion 31.
It is formed in a taper shape so as to substantially follow. The outer peripheral portion 18b contacts and seals the inner peripheral wall of the cylinder body 2.

Next, the operation of the first cup seal 18 when the piston is pushed will be described with reference to FIG. When the first piston 3 is pushed to the left in the drawing and slides in the cylinder body 2, the first pressure chamber 7 is pressurized and the pressurized hydraulic pressure is applied to the first cup seal 18. Due to this hydraulic pressure, the inner peripheral portion 18a and the right end portion 18c of the first cup seal 18 are pressed by the first piston 3, and the outer peripheral portion 18b is pressed by the inner peripheral wall of the cylinder body 2. At this time, the inner peripheral surface of the first cup seal 18 has a taper shape in which the diameter gradually decreases toward the first pressure chamber 6 along the taper portion 31, so that the inner peripheral surface of the first piston 3 is sealed. Since the entire portion 18a is obtained, the sealing property can be easily ensured.

Next, the operation of the first cup seal 18 when the piston returns will be described with reference to FIG. When the first piston 3 slides to the right in the figure, the first cup seal 1
8 moves relative to the first piston 3 to the left in the figure until the left end portion 18d of the first piston 3 comes into contact with the first retainer 15 due to the sliding resistance between the outer peripheral portion 18b and the inner peripheral wall of the cylinder body 2. At this time, since the inner peripheral surface of the first cup seal 18 has a taper shape in which the diameter gradually decreases toward the first pressure chamber 6 along the taper portion 31, the first cup seal 1
When 8 moves relatively to the first piston 3 and returns again, the working fluid in the first replenishment chamber 9 passes between the inner peripheral portion 18a and the first piston 3 and The working fluid smoothly flows when flowing into the pressure chamber 6.

[0018]

According to the present invention, a taper portion having a diameter gradually decreasing toward the pressure chamber is formed on the outer peripheral portion of the piston where the cup seal is arranged, and the inner peripheral portion of the cup seal extends along the taper portion. Since it has a shape, the sealability between the cup seal and the piston is secured over the entire inner peripheral portion of the cup seal, so that the sealability between the cup seal and the piston can be easily secured and the pressure receiving balance of the cup seal is improved. .

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the configuration of a master cylinder of this embodiment.

FIG. 2 is a cross-sectional view showing a state of the cup seal according to the present embodiment when not operating.

FIG. 3 is a cross-sectional view showing a state of a cup seal of the present embodiment when a piston is pushed.

FIG. 4 is a cross-sectional view showing a state of a cup seal at the time of returning the piston of the present embodiment.

[Explanation of symbols]

 1 Master Cylinder 2 Cylinder Body 3 First Piston (Piston) 15 First Retainer (Retainer) 18 First Cup Seal (Cup Seal) 18a Inner Circumferential Section 31 Tapered Section

Claims (1)

[Claims] 1. A hollow cylinder body, a piston slidably fitted to form a pressure chamber in the cylinder body, and a piston body formed between the outer circumference of the piston and the cylinder body. A replenishment chamber that communicates with the stored reservoir,
A cup seal that is disposed on the outer periphery of the piston and that liquid-tightly seals only from the pressure chamber to the replenishment chamber, and a periphery of the piston that is closer to the pressure chamber than the portion where the cup seal is disposed. A retainer for restricting a certain amount of movement of the cup seal toward the pressure chamber side, the diameter of which gradually decreases toward the pressure chamber in an outer peripheral portion of the piston where the cup seal is arranged. A master cylinder, characterized in that a tapered portion is formed, and an inner peripheral portion of the cup seal is formed along the tapered portion.