JPH0450522A - Disk brake piston for vehicle - Google Patents

Abstract

PURPOSE:To reduce the weight of a disk brake by admixing reinforcement additive having also heat insulating property of such as glass fiber or ceramic silicone etc., in the synthetic resin forming a piston and increasing the admixed quantity on the frictional pad pushing pressure side in comparison with that on the anti-frictional pad pushing pressure side. CONSTITUTION:A piston 6 is of a synthetic resin 10 admixed with a reinforcement additive 11. In the reinforcement additive enhanced portion 6b from the frictional pad push-move end 6a of a piston 6 to the vicinity of the fitting of a dust seal 8, the reinforcement additive 11 is admixed in a larger quantity than in other portions on the cylinder hole 5 side. For the reinforcement additive 11, a substance which possesses not only strength sufficient to reinforce the synthetic resin 10 but also heat insulating property, for example, glass fiber, ceramic, silicone and mica is used. By means of the reinforcement additive enhanced portion 6b where the heat insulation is increased on the frictional pad push pressure side of a piston 6, the braking heat occurring in the frictional pads 12, 12 is insulated, so that the braking heat is not transmitted to the bottom side of the piston 6 close to a liquid pressure chamber 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vehicular disc brake mounted on an automobile or a motorcycle or tricycle, and more particularly to a piston formed of synthetic resin.

[Conventional technology]

For example, as a vehicle disc brake using a synthetic resin piston called a resin piston,
There is one disclosed in Japanese Patent No. 62773.

This technology uses synthetic resin, glass fiber and mica.

A piston is formed by mixing reinforcing additives such as carbon fiber and copper, a fitting recess is formed in the friction pad pushing part at the tip of the piston, and an asbestos-based heat insulating plate with a small coefficient of thermal expansion is installed in this fitting recess. By fitting these, the heat of braking is blocked by the heat insulating plate, and the piston is prevented from being damaged due to thermal expansion of the heat insulating plate.

[Problem to be solved by the invention]

In this way, in a structure that combines a piston and a heat insulating plate, the number of parts and the number of assembly steps increase, which increases costs.
Furthermore, since the weight of the heat insulating plate is added to the disc brake, the unsprung load on the vehicle body increases, which is disadvantageous.

SUMMARY OF THE INVENTION An object of the present invention is to provide a piston for a vehicle disc brake that prevents braking heat from a friction pad from being transmitted to the piston without using a heat insulating plate.

[Means to solve the problem]

In accordance with the above-mentioned object, the present invention provides a piston for a vehicle disc brake formed by mixing a reinforcing additive into a synthetic resin, in which the reinforcing additive is replaced with a reinforcing additive having heat insulating properties such as glass fiber, ceramics, silicon, etc. as a thing,
It is characterized in that the amount of the reinforcing additive mixed in on the friction pad pressing side is greater than on the non-friction pad pressing side.

[For production]

With this configuration, on the friction pad pushing side of the piston,
Increased thermal insulation reinforcement additives increase thermal insulation,
It blocks the braking heat generated in the friction pad and prevents vapor lock from occurring.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

In the figure, reference numeral 1 denotes a disc brake, and a caliper 3 installed across the disc rotor 2 is connected to a disc shaft via a sliding pin (not shown) to a bracket 4 fixed to the vehicle body on one side of the disc rotor 2. The caliper 3 is a floating type supported movably in the direction, and has an action part 3a and a reaction part 3b provided on the outside of a pair of friction pads 12 and 12 that are arranged opposite to each other with the disc rotor 2 in between. It consists of a bridge portion 3c that straddles the outer periphery of the disc rotor 2 and connects it.

A cylinder hole 5 is provided in the action part 3a with the opening facing toward the disc rotor 2, and a round-shaped piston 6 is installed in the cylinder hole 5 with the opening side facing toward the disc rotor 2 and a square seal. The cylinder hole 5 is fluid-tightly and movably inserted through the cylinder hole 7 and the dust seal 8, and a hydraulic pressure chamber 9 is defined at the bottom of the cylinder hole 5.

The hydraulic pressure chamber 9 is connected to a known hydraulic master cylinder (not shown), and the hydraulic fluid that has become high pressure in the hydraulic master cylinder is
When introduced into the hydraulic chamber 9 from the inlet port 9a, the piston 6 moves forward through the cylinder hole 5 and presses one friction pad 12 against one side of the disc rotor. Next, this reaction moves the caliper 3 toward the action part 3a, and the reaction part 3
b presses the other friction pad 12 against the other side of the disc rotor 2 to perform a braking action.

The piston 6 is made of synthetic resin 10 molded into a cup shape.
The reinforcing additive 11 is mixed into the reinforcing additive 11 in the reinforcing additive increasing portion 6b from the friction pad pushing end 6a of the piston 6 to the vicinity of the fitting part of the dust seal 8.
1 is mixed in a larger amount than the other portion on the cylinder hole 5 side.

The reinforcing additive 11 is made of glass fiber, ceramics, silicon, mica, etc., which not only has the strength to reinforce the synthetic resin 10 but also has a heat insulating property, and has increased heat insulating property on the friction pad pressing side of the piston 6. The reinforcement additive-increased portion 6b with a high . This effectively prevents the occurrence of a vapor lock phenomenon due to an increase in the temperature of the hydraulic fluid.

In this way, this embodiment effectively blocks the braking heat to the piston 6 without using a heat insulating plate, so the number of parts and assembly can be reduced and manufacturing costs can be reduced, and the weight of the disc brake is light. Therefore, the unsprung load can be reduced.

In the above embodiment, the reinforcing additive increasing range set on the friction pad pressing side of the piston 6 is defined as the reinforcing additive increasing portion 6b, and the area from the friction pad pressing end 6a of the piston 6 to the fitting of the dust seal 8 However, the range of increase of the reinforcing additive of the present invention is at least as large as the friction pad of the piston when the piston is roughly divided into the half on the friction pad pressing side and the half on the anti-friction pad side. It is set within the range of the friction pad pressing side half from the moving end. Among these, in order to effectively cut off braking heat, it is more preferable to have a region protruding from the cylinder hole where heat is not easily trapped, since the heat-affected range can be reduced.

Further, the reinforcing additive may be added in a uniform manner or may be gradually increased toward the pushing end of the friction pad of the piston.

〔Effect of the invention〕

As described above, the present invention mixes reinforcing additives such as glass fiber, ceramics, silicone, etc. that also have heat insulating properties into the synthetic resin that forms the piston, and adjusts the amount of the reinforcing additives on the friction pad pressing side. Since the friction pad has increased more than the pressure side, the braking heat transmitted from the friction pad to the piston can be effectively blocked without using a heat insulating plate, so the number of parts and assembly can be reduced in man-hours and manufactured at low cost. Since the weight of the disc brake can be reduced, the unsprung load can be reduced.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which FIG. 1 is a cross-sectional front view of a disc brake, and FIG. 2 is an enlarged view of the main part of FIG. 1. 1... Disc brake, 2... Disc rotor,
3... Caliper, 3a... Action part, 12... Friction pad, 5... Cylinder hole, 6... Piston, 6a...
...Friction pad pushing end, 6b...Reinforcement additive added portion, 8...Dust seal, 10...Synthetic resin, 11.
・Reinforcement additives 2nd factor

Claims (1)

[Claims] 1. In a vehicle disc brake piston formed by mixing a reinforcing additive into a synthetic resin, the reinforcing additive is a reinforcing additive that also has heat insulating properties such as glass fiber, ceramics, silicon, etc., and the reinforcing additive is A piston for a disc brake for a vehicle, characterized in that the amount of mixture on the friction pad pressing side is greater than that on the anti-friction pad pressing side.