JP2004314743A - Master cylinder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a master cylinder capable of surely preventing galling of a cup seal even at the time of high pressure operation. <P>SOLUTION: This master cylinder M is provided with a cylinder body 1, a piston 2 having front surfaces 21a and 22a facing pressure chambers 5 and 6 and slidably fitted into the cylinder body 1, a cup seal 3 arranged between inner peripheral surfaces 11a and 14b of the cylinder body 1 and outer peripheral surfaces 21c and 22c of the piston 2 and having a U-shaped radial cross section, and a spacer ring 4 arranged on a bottom surface 32 side of the cup seal 3 and supporting the pressure from the front part actuating the cup seal 3 from the bottom surface 32 side. The spacer ring 4 is fixed on the bottom surface 32 of the cup seal 3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a plunger-type master cylinder that is used for a brake or a clutch of a vehicle and generates a hydraulic pressure in response to a driver's operation.
[0002]
[Prior art]
BACKGROUND ART Conventionally, there is a plunger-type master cylinder used for a vehicle brake or the like. This master cylinder is mainly composed of a cylinder body and a piston that slides on the cylinder body. Disc pistons on each wheel are applied by applying pressure to the brake fluid in a pressure chamber provided at the tip side of the piston with the piston. Is supplied with hydraulic pressure.
[0003]
Specifically, in the master cylinder, when not operating, the pressure chamber and a reservoir tank provided outside the cylinder body communicate with each other through a passage formed in the cylinder body, the piston, and the like. It is structured to be closed by a wall. As the master cylinder, a cup seal having a substantially U-shaped cross section formed of a soft elastic material such as a resin that functions as a valve to assist communication and release between the reservoir tank and the pressure chamber has an opening. Is provided between the cylinder body and the piston toward the pressure chamber, and a metal spacer ring that supports the cup seal so as not to move due to the pressure from the pressure chamber is provided on the bottom side of the cup seal. (For example, see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-11-217071 (paragraph number [0009], FIG. 1)
[0005]
[Problems to be solved by the invention]
By the way, in the related art, the clearance between the spacer ring and the piston is substantially constant by applying pressure to the spacer ring from the pressure chamber side via the cup seal during operation. However, as shown in FIGS. 6A and 6B, when the spacer ring SR is not operated, no pressure is applied to the spacer ring SR. Therefore, the spacer ring SR merely disposed close to the cup seal CS. May be lowered by its own weight, and when the spacer ring SR is lowered in this manner, there is a problem that the clearance CL between the lower side of the piston P and the spacer ring SR becomes large. Then, when the operation is started again with the spacer ring SR lowered, as shown in FIG. 7, a part of the cup seal CS made of resin is deformed and bites into the enlarged clearance CL. There is a possibility that so-called galling occurs and the cup seal CS becomes defective.
[0006]
Therefore, an object of the present invention is to provide a master cylinder that can reliably prevent galling of a cup seal even during high-pressure operation.
[0007]
[Means for Solving the Problems]
The invention according to claim 1 of the present invention that has solved the above-mentioned problems is characterized in that a cylinder body, a piston slidably fitted to the cylinder body with a front surface facing the pressure chamber, A cup seal disposed between an inner peripheral surface and an outer peripheral surface of the piston and having a substantially U-shaped cross section in a radial direction; and the cup disposed on a bottom side of the cup seal and subjected to pressure from the front. A spacer ring that supports the seal from the bottom side thereof, between the inner peripheral surface of the cylinder body and the outer peripheral surface of the spacer ring, or between the outer peripheral surface of the piston and the inner peripheral surface of the spacer ring. The spacer ring is fixed to a bottom surface of the cup seal in a master cylinder in which a supply passage to a front pressure chamber is formed.
[0008]
According to the first aspect of the present invention, since the spacer ring is fixed to the bottom surface of the cup seal, the spacer ring does not drop due to its own weight when the master cylinder is not operated. The clearance does not increase. That is, since the clearance between the piston and the spacer ring is always substantially constant, even if the pressure in the pressure chamber is increased by operating the master cylinder, it is possible to reliably prevent the cup seal from galling.
[0009]
The invention according to claim 2 is a cylinder body, a piston slidably fitted to the cylinder body with the front surface facing the pressure chamber, an inner peripheral surface of the cylinder body and an outer peripheral surface of the piston. A cup seal having a substantially U-shaped cross section in a radial direction, and a spacer ring disposed on a bottom side of the cup seal and supporting the cup seal to which pressure is applied from the front side from the bottom side. Between the inner peripheral surface of the cylinder body and the outer peripheral surface of the spacer ring, or between the outer peripheral surface of the piston and the inner peripheral surface of the spacer ring, to supply pressure to the front pressure chamber. In the master cylinder in which the passage is formed, the spacer ring is detachably fitted to the cup seal in the front-rear direction, whereby the position in the radial direction is regulated.
[0010]
According to the second aspect of the invention, since the radial position of the spacer ring is regulated by the cup seal, the clearance between the piston and the spacer ring is always substantially constant, and the pressure chamber is operated by operating the master cylinder. Even if the pressure becomes high, the galling of the cup seal can be reliably prevented.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the details of the master cylinder according to the embodiment of the present invention will be described with reference to the drawings. In the drawings referred to, FIG. 1 is a sectional view showing a master cylinder according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view showing details of a cup seal and a spacer ring of FIG.
[0012]
As shown in FIG. 1, the master cylinder M includes a cylinder body 1, a piston 2 slidably fitted to the cylinder body 1, a cup seal 3 disposed between the cylinder body 1 and the piston 2, And a spacer ring 4. The cylinder body 1 mainly includes a case 11 connected to a reservoir tank (not shown), and a plurality of resin molded parts 12, 13, and 14 fitted in the case 11. Oil passages 12a, 13a and 14a for communicating the reservoir tank with the pressure chambers 5 and 6 are formed in the resin molded parts 12, 13 and 14, respectively. The oil passage 12a is formed by a groove formed on the front surface of the resin molded component 12, the inner wall of the case 11, and the spacer ring 4, and the oil passage 13a is formed by a groove formed on the front surface of the resin molded component 13, The ring 4 is formed.
[0013]
The piston 2 has a first piston 21 having a front surface 21a facing a first pressure chamber 5 provided in front of the master cylinder M (the side opposite to the side to which the pressure from the brake is input), and It mainly comprises a second piston 22 having a front surface 22a facing the second pressure chamber 6 provided. Further, a first spring S1 for biasing the first piston 21 backward is provided between the first piston 21 and the case 11, and a first spring S1 is provided between the second piston 22 and the first piston 21. Is provided with a second spring S2 for urging the second piston 22 rearward. The first and second pistons 21 and 22 are provided with oil passages 21b and 22b for communicating the reservoir tank with the first and second pressure chambers 5 and 6 when the master cylinder M is not operating. Is formed.
[0014]
The cup seal 3 is a ring-shaped member made of a soft elastic material such as a resin, and is provided between the inner peripheral surface 11a on the front side of the case 11 and the outer peripheral surface 21c of the first piston 21 and the inside of the resin molded component 14. It is arranged between the peripheral surface 14b and the outer peripheral surface 22c of the second piston 22. As shown in FIG. 2, the cup seal 3 has a substantially U-shaped cross section in the radial direction, and the cup seal 3 is arranged so that the opening 31 faces the pressure chambers 5 and 6. (See FIG. 1). The spacer ring 4 is concentrically fixed to the bottom surface 32 of the cup seal 3. The fixing method may be any method, for example, adhesion by an adhesive or welding by melting the bottom surface 32 of the cup seal 3 made of resin. Further, the cup seal 3 has a function as a one-way valve, and blocks the flow from the front side (the pressure chambers 5 and 6 side) and allows the flow from the rear side (the spacer ring 4 side). I do.
[0015]
The spacer ring 4 is a metal ring-shaped member, and is disposed on the bottom surface 32 side of the cup seal 3 and supports the pressure acting on the cup seal 3 from the front side from the bottom surface 32 side. More specifically, as shown in FIG. 1, the spacer ring 4 has a rear surface supported by the front end of the resin molded part 12 or a part of the resin molded part 13, so that the cup seal 3 is formed by pressure from the front. The movement of is suppressed. Further, the outer peripheral surface 41 of the spacer ring 4 is provided with pressure chambers 5, 6 provided between the outer peripheral surface 41 and the inner peripheral surface 11 a on the front side of the case 11 or the inner peripheral surface 14 b of the resin molded component 14. A groove 41a (see FIG. 2) is formed as a supply passage.
[0016]
Instead of forming the groove 41a, a groove may be formed in the inner peripheral surface 42 of the spacer ring 4 to serve as a supply passage. In addition, a groove may be formed in the front inner peripheral surface 11a of the case 11 where the outer peripheral surface 41 of the spacer ring 4 is in contact with the outer peripheral surface 41 of the case 11 or the inner peripheral surface 14b of the resin molded component 14 as a supply passage. A groove may be formed on the outer peripheral surfaces 21c and 22c of the first and second pistons 21 and 22 with which the surface 42 contacts.
[0017]
Next, the position of the spacer ring 4 when the master cylinder M is not operated or when it is operated will be described with reference to FIG. In the following description, the position of the spacer ring 4 disposed on the front side of the master cylinder M will be described as a representative. As shown in FIG. 3 (a), no pressure is applied to the spacer ring 4 from the first pressure chamber 5 via the cup seal 3 during non-operation, but this spacer ring 4 is fixed to the cup seal 3. Therefore, it does not drop due to its own weight. Therefore, the clearance between the spacer ring 4 and the first piston 21 during non-operation is always kept constant. Since the clearance is always kept constant during the non-operation time, even if pressure is applied to the cup seal 3 from the first pressure chamber 5 during operation as shown in FIG. Of the cup seal 3 made of the resin does not cut into the small clearance between the spacer ring 4 and the first piston 21, and the galling thereof is reliably prevented.
[0018]
As described above, the following effects can be obtained in the present embodiment.
Since the spacer ring 4 is fixed to the bottom surface 32 of the cup seal 3, the spacer ring 4 does not drop due to its own weight when the master cylinder M is not operated, and the clearance between the lower side of the piston 2 and the spacer ring 4 is large. Never be. That is, since the clearance between the piston 2 and the spacer ring 4 is always substantially constant, even if the pressure in the pressure chambers 5 and 6 becomes high by operating the master cylinder M, the galling of the cup seal 3 is surely prevented. Can be prevented.
[0019]
As described above, the present invention is not limited to the above embodiment, but may be embodied in various forms.
In the present embodiment, the spacer ring 4 is fixed to the bottom surface 32 of the cup seal 3, but the present invention is not limited to this. For example, as shown in FIG. 4, a concave portion 32 a is formed on the bottom surface 32 of the cup seal 3 and a convex portion 43 a is formed on the front surface 43 of the spacer ring 4 so that the cup seal 3 can be detachably fitted to the cup seal 3. You may. Conversely, as shown in FIG. 5, a convex portion 32b may be formed on the bottom surface 32 of the cup seal 3, and a concave portion 43b may be formed on the front surface 43 of the spacer ring 4. Further, the shapes of the convex portions 43a and 32b and the concave portions 32a and 43b do not necessarily have to be curved as shown in FIGS. 4 and 5, but may be any shape.
[0020]
Since the radial position of the spacer ring 4 is regulated by attaching the spacer ring 4 to the cup seal 3 in this manner, it is assumed that the pressure inside the pressure chambers 5 and 6 becomes high during the operation of the master cylinder M. Also, galling of the cup seal 3 can be reliably prevented. In addition, by adopting a structure in which the cup seal 3 and the spacer ring 4 can be detached from each other, for example, when the cup seal 3 is to be replaced, only the cup seal 3 can be replaced without replacing the spacer ring 4. Therefore, the cost can be reduced accordingly.
[0021]
【The invention's effect】
According to the first aspect of the present invention, since the spacer ring is fixed to the bottom surface of the cup seal, the galling of the cup seal can be reliably prevented even during high-pressure operation.
[0022]
According to the second aspect of the present invention, since the radial position of the spacer ring is regulated by the cup seal, the galling of the cup seal can be reliably prevented even during high-pressure operation.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a master cylinder according to an embodiment of the present invention.
FIG. 2 is an enlarged sectional view showing details of a cup seal and a spacer ring of FIG. 1;
FIGS. 3A and 3B are an enlarged sectional view showing a state when the master cylinder according to the embodiment of the present invention is not operated and an enlarged sectional view showing a state when the master cylinder is operated.
FIG. 4 is an enlarged sectional view showing details of a cup seal and a spacer ring of a master cylinder according to another embodiment of the present invention.
FIG. 5 is an enlarged sectional view showing details of a cup seal and a spacer ring of a master cylinder according to another embodiment of the present invention.
6A is a cross-sectional view illustrating a state of a spacer ring when the conventional master cylinder is not operated, and FIG. 6B is a cross-sectional view taken along line BB in FIG. 6A.
FIG. 7 is an enlarged sectional view showing a relationship between a cup seal and a spacer ring of a conventional master cylinder.
[Explanation of symbols]
M Master cylinder 1 Cylinder body 11 Case 11a Inner peripheral surface 12, 13, 14 Resin molded part 14b Inner peripheral surface 2 Piston 21 First piston 21a Front surface 21c Outer peripheral surface 22 Second piston 22a Front surface 22c Outer peripheral surface 3 Cup seal 32 Bottom 4 Spacer ring 41 Outer peripheral surface 41a Groove (supply passage)
42 inner peripheral surface 5 first pressure chamber 6 second pressure chamber

Claims (2)

A cylinder body,
A piston slidably fitted to the cylinder body with the front face facing the pressure chamber;
A cup seal disposed between the inner peripheral surface of the cylinder body and the outer peripheral surface of the piston, and having a substantially U-shaped cross-sectional shape in a radial direction,
A spacer ring disposed on the bottom side of the cup seal and supporting the cup seal applied with pressure from the front side from the bottom side,
A supply passage to the front pressure chamber is formed between the inner peripheral surface of the cylinder body and the outer peripheral surface of the spacer ring, or between the outer peripheral surface of the piston and the inner peripheral surface of the spacer ring. In the master cylinder,
The master cylinder according to claim 1, wherein the spacer ring is fixed to a bottom surface of the cup seal. A cylinder body,
A piston slidably fitted to the cylinder body with the front face facing the pressure chamber;
A cup seal disposed between the inner peripheral surface of the cylinder body and the outer peripheral surface of the piston, and having a substantially U-shaped cross-sectional shape in a radial direction,
A spacer ring disposed on the bottom side of the cup seal and supporting the cup seal applied with pressure from the front side from the bottom side,
A supply passage to the front pressure chamber is formed between the inner peripheral surface of the cylinder body and the outer peripheral surface of the spacer ring, or between the outer peripheral surface of the piston and the inner peripheral surface of the spacer ring. In the master cylinder,
The master cylinder according to claim 1, wherein the spacer ring is fitted in the cup seal so as to be detachable in a front-rear direction, so that a position in a radial direction is regulated.

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