JPH0452499Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a seal structure for sealing a piston sliding portion of a disc brake.

[Background of the invention] Sealing of the piston sliding part in disc brakes is generally necessary to ensure good and smooth sliding of the piston, and in vehicle disc brakes in particular, it is necessary to seal the piston sliding part because the device is easily exposed to muddy water etc. , its sealing has become essential.

FIG. 3 shows a conventional example of a sealing structure for such a piston sliding portion, in which an inner circumferential groove 3' is recessed in the opening of the cylinder 2' of the cylinder body 1' so as to face the cylinder 2'. A boot 6' is installed between the piston 5' and the tip of the piston 5', and the sliding portion is sealed by the boot 6'.

Incidentally, in such a sealing structure, the boot ring 4' is required to press one end of the boot 6' radially outward against the bottom wall surface of the inner circumferential groove 3' for sealing.

As a result, the boot ring 4' deteriorates and its sealing performance deteriorates, and its assembling performance is poor, leading to an increase in the number of assembly steps.

[Purpose of the invention] The present invention was made to solve these conventional problems, and provides a piston seal structure for a disc brake that allows easy assembly of the boot and does not reduce sealing performance. The purpose is to

[Summary of the invention] The gist of the invention is to provide a cylinder body having a piston, a cylinder that accommodates the piston in a slidable manner, and one end of which is attached to the outer periphery of the distal end of the piston. In the piston seal structure of a disc brake, the piston seal structure includes a boot whose other end is assembled to the open end of the cylinder of the cylinder body, the open end is provided with a cylindrical portion, and the outer peripheral surface of the cylindrical portion is provided with a cylindrical portion. A piston seal for a disc brake, characterized in that a tapered portion whose diameter gradually increases from the opening side to the rear end side is provided, and a groove portion into which the other end of the boot fits and snaps is provided at the rear of the tapered portion. It's in the structure.

[Embodiments of the invention] The invention will be described in detail below based on the embodiments shown in FIGS. 1 and 2.

In the figure, 1 is the cylinder body, 2 is the cylinder, and 3 is the cylinder body.
7 is a circumferential groove (a cylindrical recess formed in the axial direction of the cylinder) formed in the end surface of the cylinder opening of the cylinder body 1, and 7 is a seal groove formed slightly inside the cylinder opening of the cylinder body 1. be.

As shown in FIG. 2, this circumferential groove 3 is cut out so that the tip of the inner circumferential wall surface 3a is located on the rear side than the tip of the outer circumferential wall surface 3b, and the inner circumferential wall surface 3a is cut out from the opening side. A tapered portion 3c whose diameter gradually increases toward the end side is formed, and a groove portion 3d is formed at the rear of the tapered portion 3c.

5 is a piston that is slidably fitted to the cylinder 2;
In this embodiment, it is formed in a hollow piston that opens toward the tip (cylinder opening side end), and a groove 5 is formed along the circumferential direction on the outer periphery of the tip.
a is formed.

Reference numeral 6 denotes a boot having an expandable bellows portion 6c, one of which has a swollen end 6a that fits into the concave groove 5 of the piston 5.
The other swollen end 6b is provided so as to fit into the groove 3d of the circumferential groove 3 of the cylinder body 1. At this time, the other swollen end 6b of the boot 6 is guided by the tapered part 3c formed on the inner peripheral wall surface 3a of the circumferential groove 3 and is expanded against its elastic force.
It is easy to fit into the groove 3d, and by fitting into the groove 3d over the tapered portion 3c, it is prevented from coming off.

The boot 6 is installed between the cylinder body 1 and the piston 5, thereby sealing the sliding surface between the cylinder 2 and the piston 5 from the outside air.

Note that 8 is a sealing member fitted into the sealing groove 7, indicating a liquid-tight seal on the sliding surface.

[Effects of the invention] As explained above, according to the invention, the other end of the boot is fitted into the circumferential groove formed on the open end surface of the cylinder of the cylinder body, so that the boot can be attached as easily as in the conventional case. No need for a ring, making it easy to assemble the boot, and the other end of the boot snaps into place with elasticity in the direction of reducing the diameter, resulting in stable sealing and improved sealing performance. If you can do this, you can get the desired effect.

[Brief explanation of the drawing]

Fig. 1 is a partial sectional view of a piston seal structure showing an embodiment of the present invention, Fig. 2 is an enlarged sectional view of its essential parts, and Fig. 3 is a partial sectional view of a conventional piston seal structure. . 1...Cylinder body, 2...Cylinder, 3...
...circumferential groove, 5...piston, 6...boot, 7...
Seal groove, 8...Seal member.

Claims (1)

[Scope of utility model registration request] A cylinder body having a piston and a cylinder that slidably accommodates the piston, one end of which is assembled to the outer periphery of the distal end of the piston, and the other end of the cylinder body is assembled to the open end of the cylinder of the cylinder body. In the piston seal structure for a disc brake, the opening side end portion includes a cylindrical portion, and the outer peripheral surface of the cylindrical portion is provided with a tapered portion whose diameter gradually increases from the opening side toward the rear end side, A piston seal structure for a disc brake, characterized in that a groove portion is provided at a rear portion of the tapered portion, into which the other end of the boot fits and snaps.