JPH0565732B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) This invention is an invention that can be used for automobile disc brakes to obtain a pad that can effectively prevent noise generation, and in particular can prevent noise without using a shim plate. It is configured so that it can be done. (Prior Art) As schematically shown in FIG. 5, a disc brake has linings 4, 4 bonded to a back plate 3 of a pad 2 facing each other on both sides of a rotor 1 that rotates in conjunction with the wheels of an automobile. The pad 2 is sandwiched between the claw 6 of the caliper 5 and the piston 7, and pressure oil is supplied from the oil guide port 9 to the cylinder 8 into which the piston 7 is fitted, and the piston 7 is pushed out. The pad 2 and the pad 2 on the left side of the figure in which the pawl 6 comes into contact via the caliper 5 are pressed against both sides of the rotor 1, and the wheel is braked via the rotor 1 by the friction between the lining 4 and the rotor 1. It is. However, disc brakes configured and operated in this way produce noise during braking.
may occur. This noise is likely to occur when the braking force is weak, that is, when the force applied to the brake pedal is small. The cause of this noise is that when the pedal force is low, if the contact between the caliper pawl 6, piston 7, and the pad back metal 3 is weak, the pad will vibrate when frictional vibration occurs between the rotor and the lining during braking. , and are thought to generate noise. If you press harder, this noise will subside. The harder the materials of the two contacting members, the worse the adhesion between the pawl 6 and the piston 7 and the back metal 3 of the pad. Because of this property, as a means to prevent noise, a shim plate made by applying rubber coating to both sides of a steel plate with a thickness of about 0.4 mm is interposed between the back metal 3, pawl 6, and piston 7. Attempts have been made to improve the adhesion of adjacent members such as the back plate, pawls, and pistons through the shim plate. In addition, a hard metal is thermally sprayed on the backing metal 3 to improve the adhesion between the claw and the piston, and an aluminum plate is bonded to the backing metal with a rubber adhesive, and the outer surface of the aluminum plate is also coated with a rubber adhesive. There are those that attempt to improve adhesion with pistons, etc. by painting them (as described in Jikai Publication No. 112668/1983), and those that attempt to improve adhesion by coating the entire surface of the pad with a coating film with a high zinc content. There is also one (described in Japanese Utility Model Application Publication No. 108832/1983). (Problem to be solved by the invention) However, among the above-mentioned means, thermal spraying of hard metal is not effective in preventing noise, and other means are effective in improving the adhesion between adjacent members. However, it had the disadvantage that it lacked durability and began to generate noise at an early stage. In other words, rubber coatings, rubber adhesives, zinc-containing coatings, etc. improve adhesion between adjacent parts and prevent noise generation when new, but they quickly lose this effect. . According to the research conducted by the present inventors, the noise prevention effect of the shim is related to the closeness between the back plate, the caliper pawl, and the piston.If the closeness is increased, the pads will vibrate even during low pedal force braking, which tends to generate noise. suppress,
It was found that frictional vibrations do not grow. To measure the degree of adhesion, there is a method of determining the contact resonance frequency of the contact portion by compliance measurement. The hydraulic pressure supplied to the disc brake was measured at 5 kg/cm ² , which corresponds to a light pedal force, between the case where the shim plate was used and the case where it was not used, and the differences as shown in the following table were observed.

[Table] This shows that the use of shim plates significantly improves adhesion. As mentioned above, when a rubber-coated steel shim plate was interposed between the back plate, pawl, and piston, the noise prevention effect was large at the initial stage of installation, but the reason for this was that the rubber coating It was thought that it had vibration damping properties. However, when the inventors investigated the vibration damping properties of pads and shims, the results shown in the table below were obtained.

[Table] According to this table, the damping rate of the pad itself is 5 to 10 times greater than that of the shim plate, so it can be inferred that the noise prevention effect is obtained by factors other than the vibration damping rate. Therefore, the present invention seeks a means to prevent noise by using the pad itself without using a shim plate.
This is the result obtained. (Means for Solving the Problems) This invention has a hardness of HB20 to 70 on the surface of the back metal of the pad that comes into contact with the caliper pawl and one of the pistons.
A thermally sprayed layer is formed by thermally spraying a soft metal to form a disc brake pad that prevents noise. In yet another embodiment, a heat-resistant resin coating is applied on the sprayed layer to form a disc brake pad that prevents noise. (Function) As shown in FIG. 1, in the pad 2 formed by joining the lining 4 to the back metal 3,
(or the piston 7) on the surface of the backing metal 3,
Since a soft metal such as aluminum, zinc, copper, etc. is thermally sprayed to form a thermal sprayed layer 10 with a hardness of HB20 to 70, when the caliper claw 6 (or piston 7) is pressed against this back metal 3, the soft metal A sprayed layer 10 is interposed between the back metal 3 and the claw 6 (or piston 7),
The back metal 3 and the pawl 6 (piston 7) are suitably deformed and brought into close contact with each other, thereby preventing the growth of frictional vibrations and noise generation. If the soft metal such as aluminum forming the thermal spray layer 10 is too soft, it will elongate too much, which is problematic, so a hardness of HB20 to HB70 is suitable. This soft metal exhibits a vibration-proofing effect because of the repeated pressure friction caused by the caliper claws and pistons.
This is after the contact surfaces between these and the sprayed metal have become familiar, and braking must be performed several times until then. By applying a coating 11 of a heat-resistant resin such as the like, good adhesion can be obtained from the initial stage due to the packing effect of this coating. When the sprayed layer 10 or the coating 11 is formed on the backing metal and the caliper claw 6 or the piston 7 is pressed against it, the soft metal sprayed layer 10 or the coating 11 is formed on the sprayed layer 10 or the coating 11 as shown in FIG. bulges on both sides of the pawl 6, producing a gripping effect that suppresses the pawl 6 and piston 7 from the sides, thereby increasing the adhesion as well as the anti-vibration effect.
On the other hand, even if the pawl 6 and piston 7 are coated with a sprayed layer of soft metal or a heat-resistant synthetic resin, the bulge will be as shown in Figure 4, and no grip effect will occur, so there will be no significant noise prevention effect. I can't get it. (Effects of the Invention) (1) Because of the thermal sprayed layer 10 or the thermal sprayed layer 10 and the coating 11, the adhesion between the back metal 3 and the caliper pawl 6 or the piston 7 is good, and the effect of preventing noise is great. (2) Since the durable sprayed layer 10 is made of soft metal, this noise prevention effect is highly durable. (3) By applying the coating 11 to the thermal sprayed layer 10, the noise prevention effect can be obtained from the initial use of the disc brake without waiting for the thermal sprayed layer 10 to become familiar with the caliper pawl 6 and piston 7.

[Brief explanation of the drawing]

Fig. 1 is a partial cross-sectional view of the pad taken along the line A-A in Fig. 5, showing a state in which a thermal sprayed layer has been applied to the back metal according to the present invention, and Fig. 2 is a similar cross-sectional view showing a state in which a coating has been further applied to the pad. Figure 3 is a similar sectional view showing the grip effect of the sprayed layer, Figure 4 is a similar sectional view showing the deformation when the thermal sprayed layer is formed into a pawl, and Figure 5 is a similar sectional view of a normal disc brake. FIG. 2 is a side view showing a schematic configuration. 1: Rotor, 2: Pad, 3: Back metal, 4: Lining, 5: Caliper, 6: Pawl, 7: Piston,
8: Cylinder, 9: Oil filler port, 10: Thermal spray layer, 1
1: Coating.

Claims (1)

[Claims] 1. The contact surface of the back metal 3 of the pad 2 that contacts one of the caliper pawl 6 and the piston 7 has a hardness of HB20 to
A pad for a disc brake that prevents noise, characterized by forming a thermal spray layer 10 by thermally spraying a soft metal of 70. 2. A disc brake pad for preventing noise according to claim 1, wherein a heat-resistant resin coating 11 is applied on the thermal spray layer 10.