JP3036187B2 - Brake pads for disc brakes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake pad for a disc brake.

[0002]

2. Description of the Related Art As one type of brake pad for a disc brake, there is a brake pad for a disc brake having a back metal having a plurality of through holes and a friction pad adhered to the surface of the back metal. Is shown in Japanese Utility Model Laid-Open Publication No. 1-132825. In the brake pad, a part of the friction pad is fitted in each through-hole of the back metal, and the action of the portion of the friction pad fitted in each through-hole is sufficient for the shear force during braking. It was developed with the aim of obtaining resistance strength.

In general, in a brake pad, it is necessary to prevent the occurrence of vibration and the occurrence of brake squeal between the brake pad and the disk rotor. In the brake pad disclosed in the above publication, each through hole is formed. In order to prevent the occurrence of brake squeal due to the lowering of the rigidity of the backing metal, a weight member is disposed in each through-hole of the backing metal, and a means for changing the balance with respect to the weight change of the backing metal or the vibration of the friction pad is adopted. In other types of brake pads, a means for forming the friction pad in a porous manner to improve its damping property, a means for increasing the amount of lubricant in the friction pad to reduce the vibration source, and the like are employed.

[0004]

Each of these means has a considerable effect on brake squeal generated during general running of the vehicle because the vibration generated between the brake pad and the rotor is relatively small. . However, when moisture adheres to the surface of the friction pad, the vibration between the brake pad and the rotor becomes extremely large, and the above-described means may not provide the effect of preventing brake squeal.
The effect of moisture interposed between the friction pad and the rotor on brake squeal is largely related to the magnitude of the interposed moisture.

[0005] That is, when the amount of intervening moisture is large, a thick water film is formed between the friction pad and the rotor, the contact surfaces of these two are easily separated, and the friction coefficient μ is governed by the shearing force of water. That is, since the shearing force is very small, the friction coefficient μ decreases. On the other hand, when the amount of intervening moisture is reduced, there is a locally strong bonding site between the friction pad and the rotor due to the action of water molecules between the friction pad and the rotor. The friction coefficient μ at the connection site is high and the friction surface of the friction pad is in an unstable state, causing the friction pad to vibrate and cause brake noise. Further, such moisture often occurs in a vehicle left outdoors, especially in the early morning. Therefore, an object of the present invention is to prevent the occurrence of brake squeal due to such moisture adhering to the friction pad.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a brake pad for a disc brake, comprising a back metal having a plurality of through holes, and a friction pad adhered to the surface of the back metal. Place a water-absorbing agent in the
An agent is brought into contact with the back surface of the friction pad . In the present invention, the water-absorbing agent can be mentioned zeolite, a water absorbing agent such as silica gel
You .

[0007]

In the brake pad for a disc brake according to the present invention, a water absorbing agent is provided in each through hole of the back metal.
And the water absorbing agent is brought into contact with the back surface of the friction pad, so that moisture adhering to the surface of the friction pad passes through the innumerable pores formed in the friction pad to absorb the water. To the agent
Water and gradually decrease. Therefore, the moisture adhering to the friction pad disappears quickly, and the cause of the brake squeal can be eliminated. The water once absorbed by the water-absorbing agent evaporates when the temperature of the friction pad rises due to frictional heat, or is easily scattered to the outside air when the vehicle travels and wind is applied. When a shim for preventing squeal is attached to the back metal, it is preferable to make a hole in the shim in contact with the through hole.

[0008] In the friction pad constituting the brake pad, there are countless continuous pores generated when gas generated during thermoforming scatters to the outside inside the friction pad. There is a material having poor affinity for the resin, and a space formed around the material without the molten resin flowing therein exists. These spaces and pores are connected to each other to form a communication passage communicating with the outside. Thus, water adhering to the surface of the friction pad through these myriad communication passage is water to reach the water-absorbing agent,
In addition, the absorbed water is scattered to the outside due to a rise in the temperature of the friction pad and wind caused by running the vehicle. For this reason, water absorbing agent
The water-absorbing ability is maintained for a long time.

[0009] Since the water in the friction pad is forcibly absorbed by the water absorbing agent , the existence time of the water in the friction pad is shortened, and the generation of rust in the friction pad is suppressed. If rust is generated inside the friction pad, the rust will cause the inside of the friction pad to expand and the binder will be mechanically broken, thereby reducing the strength of the friction pad and causing the friction pad to use a metal material such as steel fiber. When the metal material is included, the metal material itself rusts to cause a reduction in strength. However, when the generation of rust is suppressed or prevented as described above, the reduction in strength of the friction pad is suppressed or prevented.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Brake Pad) As shown in FIGS. 1 and 2, a brake pad according to the present invention comprises a backing metal 11, a friction pad 12, and a plurality of filling members 13. 13 is back metal 11
Is filled in each through hole 11b formed in the main body 11a. The filling member 13 is composed of a bottomed cylindrical container 13a and a group of granular zeolite 13b accommodated in the container 13a, and the group of zeolite 13b is a friction package.
Contact with the back surface of the gate 12 . The friction pad 12 is formed into a pre-formed body using raw materials having the following composition, and the pre-formed body is integrated with the surface of the back metal 11 under the following conditions. Further, the container 13a is formed of the same material as the friction pad 12, is preformed in the same manner as the friction pad 12, is filled in each through-hole 11b of the back metal 11, and holds the zeolite 13b. 11 and the friction pad 12.

Composition of preformed body (vol%): aromatic polyamide fiber 25 potassium titanate whisker 6 graphite 6 cashew dust 14 magnesium oxide 6 barium sulfate 13 antimony trisulfide 2 slaked lime 6 phenolic resin 17 preforming conditions and integration Mix the raw materials of the above composition using a V-type blender,
Thereafter, pressure was applied at a pressure of about 600 kg / cm ² for about 30 seconds to prepare a preform of the container 13a of the friction pad 12 and the filling member 13. The preformed body of the obtained container 13a is
1, the zeolite 13b is housed in the same container 13a, and the preform of the friction pad 12 is placed on the surface of the backing metal 11. In this state, these are pressed in a mold. The resultant was integrated by heating at 400 kg / cm ² at 160 ° C. for 10 minutes and then heat-treated at 250 ° C. for about 3 hours to produce a brake pad in which the back metal 11, the friction pad 12 and the filling member 13 were integrated. The brake pad is referred to as an example pad A.

(Experiment 1) A brake pad (comparative pad) in which the pad A and a part of the friction pad 12 are filled in the respective through holes 11b of the back metal 11 and the filling member 13 is omitted is used. Two vehicles of the same type equipped with disk brakes to which both pads were attached were left outdoors overnight and a brake squeal test was performed ten times in the early morning. As a result, the number of occurrences of brake squeal was four in the pad A of the embodiment, while the number of brake squeals was eight in the pad of the comparative example.
It was confirmed that the occurrence of brake squeal was greatly suppressed in Example Pad A. Further, when the pad of Example A and the pad of Comparative Example were left outdoors overnight, and pressed against the surface of the pad with moisture absorbent paper, in Example Pad A, almost no moisture was adsorbed to the absorbent paper.
In the pad of the comparative example, moisture was adsorbed on the entire surface of the hygroscopic paper. From this result, it is clear that in the pad A of the embodiment, the moisture on the surface of the friction pad 12 has been removed, and it is recognized that this has the effect of reducing brake squeal.

(Experiment 2) A heat pad was applied to Example Pad A to increase the number of continuous pores by applying heat shear (Example Pad B). Using a friction pad with increased pores (Example Pad C), two vehicles of the same type equipped with a disc brake with both pads mounted thereon were left outdoors overnight, and an early morning brake squeal test was performed. Was performed 10 times each. As a result, both pads B and C generated brake squeals twice, exhibiting the effect of increasing continuous pores.

When the former heat shear is carried out, combustion gas is generated, and this combustion gas is weak inside the friction pad,
For example, continuous pores are increased by breaking through weak portions between pores. In the case of performing heat shear, if moisture is included in the vicinity of the surface of the friction pad, the moisture is vaporized, the pressure of the generated gas is increased, and the effect of increasing continuous pores is great. In addition, when the latter heat treatment is performed, the uncured resin is cured and gas is generated at this time, but when this gas is scattered from both front and back without scattering from the entire peripheral surface of the friction pad, the gas is generated on both front and back surfaces. The number of communicating continuous pores increases.

[Brief description of the drawings]

FIG. 1 is a rear view of a brake pad according to an embodiment of the present invention.

FIG. 2 is a sectional view of the brake pad taken along line 2-2 in FIG. 1;

[Explanation of symbols]

11: Back metal, 11b: Through hole, 12: Friction pad, 13
... filling member (water absorbing means), 13a ... container, 13b ... zeolite (adsorbent).

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16D 49/00-71/04

Claims (1)

(57) [Claims] 1. A brake pad for a disc brake, comprising: a back metal having a plurality of through holes; and a friction pad adhered to a surface of the back metal, wherein a suction pad is provided in each through hole of the back metal.
Arrange a liquid agent and contact the water-absorbing agent on the back of the friction pad.
A brake pad for a disc brake characterized by being touched .