JPH0237297Y2 - - 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 pads have been used as brake pads 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. or,
Effective insulation takes time to dissipate heat, creating extremely hot areas during continuous braking that can cause unforeseen problems.

[Means for solving the problem] As a result of various studies in view of the above-mentioned problems, the inventor of the present invention has 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, leading to the present invention.

The heat insulating body for a piston of a disc brake of the present invention is a heat insulating body fitted into an opening of a piston facing a brake pad of a disc brake so as to fill substantially the entire inside of the piston, and The body slightly protrudes from the opening surface of the piston toward the brake pad, and has a shape such that the protruding portion does not extend beyond the opening surface, and the heat insulating body has an air passage on the brake pad contact surface. , and the heat insulating body is made of a molded body of phenolic resin or a molded body of ceramic material.

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 oil 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 part facing the brake pad 2, and the shape of the piston insulator 5 of the present invention is such that it fits into the opening so as to fill the inside of the piston 4. At times, it has a dimension that slightly projects from the opening surface of the piston 4, and this projecting portion does not extend beyond the opening surface, and has an air passageway in the contact surface of the brake pad 2.

Fitting the heat insulating body 5 to the piston 4 so as to fill substantially the entire inside of the piston 4 allows the heat insulating body to not be damaged even under extremely strong pressure.
It has also been found that this is necessary in order to strictly maintain the distance between the brake pad 2 and the piston 4.

The reason why the heat insulating body 5 slightly protrudes from the opening surface of the piston 4 is because the piston 4 pushes the brake pad 2 through the insulating body 5 when the brake is applied, so the frictional heat generated in the brake pad 2 is directly transferred to the piston 4.
This is because there is no conduction.

Usually, the above protrusion is several mm or less.

Moreover, the reason why the protruding portion of the heat insulating body 5 is formed in a shape that does not extend beyond the opening surface is as follows.
If it is extended, the strength is weak because the length of that part is less than a few mm as mentioned above, and the piston 4 pushes the brake pad 2 through this extended part, further accelerating the damage and eventually damaging the insulation. This is because the damage to the entire 5.

Furthermore, the reason why the airflow passage 7 is formed on the contact surface of the brake pad 2 of the heat insulator 5 is to effectively radiate frictional heat. In addition, effective insulation takes time to dissipate heat and prevents extremely hot areas from forming during continuous braking, which could cause unforeseen problems. The dimensions and shape of the airflow passage 7 are appropriately determined in consideration of the heat dissipation effect and the strength of the heat insulator 5, and are usually as shown in the cross-sectional view and top view in FIGS. 2a and a'.
This is obtained by notching the surface of the heat insulator 5 that contacts the brake pad 2, that is, the surface of the heat insulator 5 that contacts the brake pad 2 (inside the protrusion). As will be described later, when the contact surface of the heat insulating body 5 with the brake pad 2 is protected by a metal plate (as shown in FIG. 2 c, d, etc.), the heat insulating body 5
Although the surface of the piston may not come into direct contact with the brake pad 2, in the piston heat insulator of the present invention,
The brake pad contact surface refers to the surface of the heat insulator 5 on the side that presses the brake pad 2, regardless of the presence of inclusions such as the metal plate described above.

The material of the piston heat insulating body 5 of the present invention is a molded body of phenolic resin or a molded body of ceramic material in view of its heat insulating properties and strength.
The above-mentioned phenolic resin molded product refers to a molded product made of 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.

Further, it is recommended that the heat insulating body 5 of the present invention has a shape having a hole or a gap that allows air to flow between the bottom of the piston 4 and the opening, as shown in FIG. 2b. This is piston 4 and insulator 5
Insertion may be difficult due to the air that gets in between when inserting the piston, or when the disc brake is activated, the air trapped between the piston 4 and the heat insulator 5 expands thermally, causing the heat insulator 5 to shift to the mounting position of the piston 4. This is to prevent it from being pushed out. Fig. 2b shows a case where a through hole 8 is provided in the center of the heat insulator 5 and a groove 9 is provided on the outside of the heat insulator 5, but in the case of the present invention, either one or both may be provided. good. Further, it is preferable to form a groove on the surface that contacts the bottom of the opening, and to communicate this groove with the hole 8 or groove 9.

For disc brakes, when the brake pads are replaced for maintenance etc., use a tool such as a screwdriver to remove the heat insulator 5.
Since the surface may be damaged, it is recommended to protect the protruding portion of the heat insulating body 5 with a metal plate 12 made of iron or stainless steel, as shown in FIGS. 2c and 2d. In this case, the protruding portion is usually covered with a cap-shaped metal plate 12 as shown in the figure. Note that the metal plate 12 is mounted so as not to come into contact with the piston 4. This is because the heat of the brake pad 2 is not transmitted to the piston 4 through the metal plate 12, so the distance between the piston 4 and the metal plate 12 must be carefully considered during installation. 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 insulating effect of the heat insulating body of the present invention will be explained below using an example.

The heat insulator 5 of the present invention is made by molding a heat insulator having the shape shown in Fig. 2c with phenolic resin and attaching a stainless steel metal plate 12. The relationship with hydraulic oil temperature was determined. The results are shown in curve 1 of 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 heat insulating body of the present invention eliminates direct contact between the brake pad and the piston, and the apparent thickness of the heat insulating body is only at the portion protruding from the piston (usually several mm or less). It is presumed that the effective heat insulation effect of the heat insulating body is achieved by the thickness (size) of the whole heat insulating body and the fact that the heat insulating body is provided with air flow passages for cooling.

[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, it can be installed as a subsequent improvement 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 the drawing]

Figure 1 is a cross-sectional view of a disc brake using the disc brake piston heat insulator of the present invention, Figure 2 is a cross-sectional view and top view of the heat insulator of the present invention, and Figures 3 and 4 are conventional heat insulators. The cross-sectional view of the body and FIG. 5 are graphs showing the relationship between the number of braking times and the temperature of brake hydraulic fluid in a disc brake using the heat insulating body of the present invention.

Claims (1)

[Scope of utility model registration request] A heat insulating body fitted into an opening of a piston facing a brake pad of a disc brake so as to fill substantially the entire inside of the piston, the heat insulating body facing toward the brake pad from the opening face of the piston. The heat insulating body has a shape that protrudes slightly and the protruding portion does not extend beyond the opening surface, and the heat insulating body has an air flow passage on the contact surface with the brake pad, and the heat insulating body is a molded body of phenolic resin. Or a heat insulating body for a piston of a disc brake, characterized in that it is made of a molded body of ceramic material.