JP2765301B2 - Non-asbestos disc pad - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-asbestos-based disc pad used for a braking member of an automobile or the like.

[0002]

2. Description of the Related Art Conventionally, asbestos fiber has been used as a friction member for a brake pad of a disc brake. Recently, however, the harmfulness of asbestos fiber has been pointed out, and metal fibers such as steel fiber have been used as an alternative fiber to asbestos fiber. Materials as main components have been used.

However, the thermal conductivity of metal fibers is higher than that of conventional asbestos fibers, so that the rate of transmission of frictional heat generated during braking to the brake oil side increases, so that a so-called vapor lock phenomenon easily occurs. For this reason, it has recently been proposed to interpose a heat insulator (hereinafter referred to as an insulator) having a lower thermal conductivity than the friction member between the friction member and the back metal constituting the disk pad.

[0004]

The main purpose of the insulator is to reduce the thermal conductivity so that frictional heat is not transmitted to the brake oil. However, as the wear of the disc pad progresses, the insulator portion becomes a surface. May be exposed. Therefore, it must have a certain degree of friction characteristics (friction coefficient, wear resistance, etc.).

Therefore, it is required to use a material having a heat insulating effect in addition to a material similar to the material of the friction member as the insulator. However, the characteristics of the disk pad include not only the friction coefficient and the wear resistance, but also the noise generated when the brake is depressed, which has recently become a problem, and a disk pad with less noise has been demanded.

The cause of the squeal often depends on the composition (mixing ratio, shape, etc.) of the disc pad. Conventionally, the composition is examined or the surface shape (parallelism, flatness, chamfer for improving the surface contact) is improved. At present, it has not been possible to obtain satisfactory products.

An object of the present invention is to provide a non-asbestos-based disc pad which does not have the above-mentioned disadvantages.

[0008]

As a result of various studies on the above-described method of improving the squeal, the present inventors have focused on an insulator material which has been mainly used only for heat insulation, and found that the insulator material has an elastic modulus. It has been found that the squealing rate can be greatly reduced by adjusting the value of, and the present invention has been completed.

[0009] The present invention relates to a method in which the friction between the back metal and the friction member is 8 at room temperature .
GPa or less, 8 GPa or more at room temperature between the non-asbestos brake pad and back metal and the friction member made by interposing an insulator having a modulus below 4.2GPa at 120 ° C.
Below, an ink having a modulus of elasticity of 4 GPa or less at 120 ° C.
The present invention relates to a non-asbestos-based disc pad having a heat exchanger .

In the present invention, as the friction member, metal fibers such as steel fibers, copper fibers and brass fibers, organic fibers such as aramid fibers and phenol fibers, fibrous materials composed of ceramic fibers, phenol resin, NBR rubber, SBR
Binders such as rubber and natural rubber, fillers such as barium sulfate, calcium carbonate and magnesium carbonate, and lubricants such as graphite and molybdenum disulfide are used.

[0011] Further, the insulator is similar to the friction member because the disk pad is worn away and the friction member portion is lost, and the friction coefficient and the wear characteristics must not be largely changed even if only the insulator portion is used. The material is used, and the elastic modulus is decreased from room temperature to less than 120 ° C. by 8 GPa or less to 120 ° C. by reducing the material having large thermal conductivity or increasing the material having small thermal conductivity.
What has been adjusted so that the above becomes 4 GPa or less is used.

It is necessary to use an insulator having an elastic modulus of 8 GPa or less from room temperature to less than 120 ° C. and 4 GPa or less at a temperature of 120 ° C. or more. There is a disadvantage that squealing occurs when the brakes are applied to the vehicle and the brake is depressed.

[0013]

The squeal at the time of braking of the car is the vibration generated by the fluctuation of the frictional force generated between the surface of the disk pad and the surface of the rotor, which is the mating material, is transmitted to the vehicle body and air through the back metal of the disk pad and the caliper. By lowering the elasticity of the insulator, vibrations caused by friction fluctuations generated on the surface of the disk pad can be absorbed to prevent the vibrations from being transmitted to the back metal and the caliper.

[0014]

Embodiments of the present invention will be described below. 20% by volume of 2 mm long steel fiber (Rose), 5% by volume of aromatic aramid fiber (Kevlar fiber, trade name of DuPont), phenol resin (manufactured by the company, not for sale) as a friction member
25% by volume, 5% by volume of NBR powder (NIPOL1411, trade name of Zeon Corporation), 30% by volume of graphite (KS-15, trade name of Lonza) and 15 volumes of barium sulfate (barite powder, manufactured by Gokin Corporation) % Was sufficiently mixed with a Henschel mixer to obtain a molding powder for a friction member.

On the other hand, as an insulator, the compositions shown in Table 1 were weighed in the proportions of A, B, C and D, and sufficiently mixed with a Henschel mixer similar to the above to obtain a molding powder for insulator. In addition, ceramic fiber (SC bulk 12
60, Nippon Steel Chemical Co., Ltd.).

Thereafter, a back metal is placed in a mold, and the upper surface thereof is filled with a molding powder for an insulator and a molding powder for a friction member in this order, and then at 1.47 × 10 ⁷ Pa (150 kgf / cm ² ) and 170 ° C. for 10 minutes. The molded body was heated under pressure under the conditions described above, and an insulator was interposed between the back metal and the friction member. Then, the surface was finished to obtain a non-asbestos disc pad.

Next, the obtained non-asbestos-based disc pad A,
B, C and D were mounted on a car (Cedric manufactured by Nissan Motor Co., Ltd.), and the frequency of squealing during braking (number of squeals / total number of brakes × 100%) was determined. Also cut out insulators from non-asbestos-based disc pads A, B, C and D,
Measure the viscoelasticity from room temperature to 360 ° C.
Were determined. Table 2 shows the results together.

[0018]

[Table 1]

[0019]

[Table 2]

As a result of comparing A, B, C and D, it is clear from Table 2 that A , B and C whose elastic moduli are within the range of the present invention have a low squeal frequency. On the other hand, it can be seen that D whose elastic modulus is out of the range of the present invention has a higher squeal frequency.

[0021]

The non-asbestos-based disk pad according to the present invention is a non-asbestos-based disk pad which is extremely industrially suitable, since the squealing rate can be greatly reduced without changing the friction characteristics.

Claims (2)

(57) [Claims] 1. The method according to claim 1 , wherein the gap between the back metal and the friction member is 8 GPa at room temperature .
Hereinafter, 4 120 ° C.. A non-asbestos-based disc pad in which an insulator having an elastic modulus of 2 GPa or less is interposed. 2. At room temperature, 8 GPa between the back metal and the friction member.
Below, an ink having an elastic modulus of 4 GPa or less at 120 ° C.
A non-asbestos-based disc pad with a schlator interposed.