JPH0520905Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a heat insulator for the piston of a disc brake, and more specifically, it blocks heat conduction to prevent the temperature of the brake hydraulic fluid from rising due to the heat generated by the disc brake. This invention relates to a heat insulator for a piston of a disc brake.

[Prior Art] In recent years, sintered metal or semi-metallic brake pads have been used for disc brakes due to their heat resistance and fade characteristics. These brake pads are controlled using hydraulic pressure such as oil pressure. However, since brake pads made of the above-mentioned friction material have good conductivity for the heat generated during use, the brake hydraulic oil used for the above-mentioned control increases, causing so-called vapor lock, etc., and impairing the brake function. There were other inconveniences.

Therefore, when using the brake pad, it is necessary to suppress the temperature rise of the brake hydraulic oil by some method.For this reason, conventional methods have been used to provide a heat insulator 10 on the surface of the hydraulic piston 4, etc.
(Fig. 4) or attaching the heat insulator 10 to the back of the brake pad 2 by sandwiching it between metal plates 11 (Fig. 4)
etc. are taken.

[Problems to be solved by the invention] However, in the method shown in Fig. 4 above, increasing the thickness of the heat insulator reduces the effective thickness of the friction material layer; There was a problem that the thinner the material, the less its insulation effect. Further, in the method shown in FIG. 3, the heat insulating body alone is insufficient in strength and is likely to be damaged. Furthermore, in any case, the distance between the brake pad and the piston must be maintained strictly for safety and mechanical reasons, so the heat insulator 10 must be handled with care during use and maintenance.
It had to be firmly fixed so that it would not fall off, which caused the problem of complicating the structure.

[Means for solving the problem] As a result of various studies in view of the above problems, the inventors of the present invention have developed a piston having a specific shape and a specific material that fits into the opening of the piston. The inventors have discovered that the above problem can be solved by using a heat insulator for pistons, and have come up with the present invention.

That is, the heat insulating body for a piston of a disc brake according to the present invention has a heat insulating body made of a molded body of phenolic resin or ceramic material, which is placed in the opening of the piston facing the brake pad of the disc brake, and is directed from the opening face of the piston toward the brake pad. The outer periphery of the protruding portion is fitted so as to fill substantially the entire inside of the piston in a form in which the outer periphery of the protruding portion forms a notched annular step at a position below the inner surface of the piston opening, and is fitted into the opening of the piston. A structural feature is that a through hole or groove for air circulation is formed from the bottom of the heat insulator to the brake pad contact surface.

The present invention will be explained in detail below.

FIG. 1 is a sectional view of a disc brake using the piston heat insulator of the present invention. Figure 1 shows
Brake pads 2 are provided on both sides of the disc 1, and the brake pads 2 are filled with brake hydraulic fluid 3.
It is driven by pressure from the piston heat insulator 5 and caliper 6 of the present invention provided on the piston 4 through hydraulic pressure.

The piston 4 has an opening in the portion facing the brake pad 2, and a heat insulator 5 is fitted into the opening. The shape of the heat insulator 5 is such that it slightly protrudes from the opening surface of the piston 4 toward the brake pad 2.
An annular stepped portion 12 is formed on the outer periphery of the protruding portion and is cut out below the inner surface of the piston opening, and in this form, the piston is fitted so as to fill substantially the entire interior of the piston.

In the above heat insulator structure, the reason why the brake pad contact surface of the heat insulator 5 is slightly protruded from the opening surface of the piston 4 is because the brake pad 2 is caused by the piston 4 pressing the brake pad 2 through the heat insulator 5 during brake operation. This is to prevent the frictional heat of the piston 4 from being directly transmitted to the piston 4, and the degree of protrusion is usually sufficient to be several mm or less.

An annular step 12 is formed by cutting out the outer periphery of the protruding part at a position below the inner surface of the piston opening, and when the brake is applied, the weak protruding part is pressed by the brake pad 2, causing distortion and extending outward from the periphery. Even if it extends, it functions effectively to prevent the extended portion from rubbing against the inner surface of the piston opening and breaking, or from being caught between the brake pad 2 and the piston 4 and being damaged. .

By filling substantially the entire inside of the piston 4 with the heat insulating body 5 of this type, the main body of the heat insulating body will not be damaged even if strong pressure is applied, and the gap between the brake pad 2 and the piston 4 will always be kept strictly. Retained.

The material of the piston heat insulating body 5 of the present invention is a molded body of phenol resin or a molded body of ceramic material in view of its heat insulating properties and strength.
The above-mentioned phenolic resin molded article refers to one molded from phenolic resin, and here, phenolic resin is a well-known thermosetting resin obtained by reacting phenols and aldehydes, but it is partially modified. Including those who did. Furthermore, when using it, it is recommended to include heat-resistant fibers as appropriate in order to increase the strength etc.

As this heat-resistant fiber, any conventionally known heat-resistant fiber can be used, but at least one of ceramic fiber, glass fiber, and carbon fiber is particularly recommended.

On the other hand, as the ceramic material molding, any well-known ceramic material molding can be used, but it is appropriately selected from the viewpoints of price, breaking strength, etc.

In addition, in this invention, in terms of ease of molding, cost, etc.
A molded body of phenolic resin is recommended.

Furthermore, as shown in FIG. 2, the piston heat insulator of the present invention has a through hole 7 or groove 8 formed for air circulation from the bottom of the heat insulator 5 fitted into the opening of the piston 4 to the brake pad contact surface. has been done.
This may be due to difficulty in inserting the heat insulator 5 into the piston 4 due to the air that gets in between, or when the disc brake is activated, the air trapped between the piston 4 and the heat insulator 5 expands thermally. This is to prevent the heat insulator 5 from being pushed out from the mounting position of the piston 4. 2a shows a case where a through hole 7 is provided in the center of the heat insulator 5, and FIG. 2b shows a case where a groove 8 is provided on the outside of the heat insulator 5, but in the case of the present invention, either can be used. Both may be provided. Also, a groove is formed on the surface that contacts the bottom of the opening, and this groove and the hole 7
Alternatively, it is preferable to make the grooves 8 communicate with each other. For disc brakes, when the brake pads are replaced for maintenance etc.
Since the surface of the heat insulator 5 may be damaged by a tool such as a screwdriver, it is recommended to protect the protruding part of the heat insulator 5 with a metal plate 9 made of iron or stainless steel, as shown in Figure 2c. be done. In this case, usually a cap-shaped metal plate 9 as shown in the figure is placed over the protrusion or portion. Note that the metal plate 9 is mounted so as not to come into contact with the piston 4. This is because the heat from brake pad 2 is transferred to metal plate 9.
This is because the distance between the piston 4 and the metal plate 9 when installed is as follows:
must be fully considered. Therefore, it is recommended that the shape of the protruding portion of the heat insulator 5 be selected to have a notch portion between it and the piston as shown in FIG.

[Example] The heat insulation effect of the heat insulating body of the present invention will be explained below using an example.

A heat insulator having the shape shown in Fig. 2c is molded with phenolic resin, and a stainless steel metal plate 9 is attached to the heat insulator 5 of the present invention. The relationship with hydraulic oil temperature was determined. The results are shown in curve 1 in FIG. Curve 2 in Fig. 5 is when the heat insulator 5 is not installed, curve 3 is when the conventional heat insulator shown in Fig. 3 is provided, and curve 4 is when the conventional heat insulator shown in Fig. 4 is provided. It is. As is clear from FIG. 5, the disc brake provided with the heat insulator of the present invention had a lower rise in brake hydraulic oil temperature than the conventional heat insulator, and exhibited a good heat insulation effect.

[Function] Due to its shape, the insulating body of the present invention eliminates direct contact between the brake pad and the piston, and the apparent thickness of the insulating body is only at the part that protrudes from the piston (usually several mm or less). It is assumed that this is because the effective insulation effect of the heat insulating body is achieved by the thickness (size) of the whole heat insulating body.

[Effects] The heat insulating body of the present invention is extremely easy to install compared to conventional products, and since the apparent thickness of the heat insulating body is small, the thickness of the friction material can be sufficiently thickened.
Furthermore, as a subsequent improvement, it can be installed on conventional commercially available disc brakes without any special processing, and its insulation effect is better than that of conventional products. Therefore, it is industrially excellent.

[Brief explanation of drawings]

Figure 1 is a sectional view of a disc brake using the disc brake piston heat insulator of the present invention, Figure 2 is a sectional view of the heat insulator of the present invention, and Figures 3 and 4 are cross sections of a conventional heat insulator. FIG. 5 and FIG. 5 are graphs showing the function of the number of brakings and the temperature of brake hydraulic fluid in a disc brake using the heat insulating body of the present invention.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. A heat insulating body made of a molded body of phenolic resin or ceramic material is located at the opening of the piston facing the brake pad of a disc brake, and slightly protrudes from the opening of the piston toward the brake pad. The outer periphery of the heat insulating body is fitted so as to form an annular stepped portion cut out at a position below the inner surface of the piston opening, and is fitted so as to fill substantially the entire inside of the piston, and from the bottom of the heat insulating body fitted into the opening of the piston. A heat insulator for a piston, characterized in that a through hole or groove for air circulation is formed on a contact surface of a brake pad. 2. The heat insulator for a piston according to claim 1, wherein a metal plate is disposed at the tip of the protruding portion of the heat insulator without contacting the piston.