JP2008164081A - Brake pad - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brake pad improved in initial parking effect while ensuring large braking torque with small difference between an initial friction coefficient and a friction coefficient after used a considerable number of times even if using the brake pad with the same friction coefficient. <P>SOLUTION: The brake pad formed with a tapered part on a friction surface of a friction material containing at least base material fiber, a binding material and a filler is formed with the tapered part occupying 1/3-1/2 of the area of the friction surface on the inner peripheral side of a contact position of the friction surface with a rotor and having a tapered part depth of 0.05-0.5 mm. It is preferable to set the tapered part depth to 0.1-0.25 mm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a printing material used for a disk brake with a built-in parking mechanism such as various vehicles and industrial machines, and more particularly to a brake pad that stabilizes the initial effectiveness of the brake.

  As a parking brake for a vehicle, there are a brake having a parking brake in addition to a dynamic brake and a brake used for parking by pressing a dynamic brake pad mechanically instead of hydraulically. The latter is generally called an integral type brake. In general, the friction material increases the contact area of the sliding surface due to sliding with the counterpart material, and reaches the target effectiveness level. Generally, the initial efficacy is slightly lower.

  Basic performance required for brake pads includes high efficacy, good thermal stability, long life, and no brake squeal, but ensure initial efficacy after installation. Is also an important item. However, in the conventional parking brake, the contact state between the friction material and the counterpart material (disk rotor or drum), that is, the surface roughness, flatness, curvature, etc., becomes unstable, resulting in an initial effect. May vary, resulting in insufficient efficacy.

  For this reason, in “Patent Document 1”, a taper having a width of 20 mm or less is provided on the outer periphery or inner periphery of the brake pad, and the pressure center of gravity is moved only in the initial stage of use, thereby enabling adjustment of generated torque. At that time, when using a brake pad having a high initial friction coefficient, as shown in FIG. 3 (a), the brake pad 3 is cut out along the outer periphery of the brake pad 3 into a belt shape having a width of 20 mm or less, or (b) ), The maximum width is 20 mm or less in a kamaboko shape. The notch is indicated by 4. On the other hand, when using a brake pad having a low initial friction coefficient, the same notch 4 as in FIG. 3 is provided along the inner periphery of the pad 3 as shown in FIGS.

In addition, in “Patent Document 2”, in order to improve the initial effectiveness of the brake pad and suppress the generation of noise, a pad having a shape in which the surface is partitioned in a lattice pattern and a plurality of sections arranged in a staggered pattern are recessed is devised. ing. In “Patent Document 3”, a friction material having a mesh having a mesh opening of 0.05 to 2 mm is devised on the friction surface. However, in either case, it was impossible to suppress the change in the coefficient of friction when the disk brake was used and when it was stabilized after use, and it was not possible to supply a brake pad that was stable in performance.
JP-A-62-274121 JP-A-8-277865 JP-A-4-266888

In order to improve the initial effectiveness of the brake pad, improvements have been made to cut out the end face of the friction surface of the brake pad or to add a grid-like recess to the friction surface as described above. Since there are few notches, it does not produce a sufficient effect, and when a grid-like dent is inserted, the contact surface with the rotor may be too wide and contact with each other, so it can be said that the initial efficacy has improved sufficiently. There wasn't. In particular, when notching the end face of the friction surface, the notch becomes deeper due to the work work, so that it will not be in a normal state unless it is used a considerable number of times. I didn't know if there was.
Therefore, the problem of the present invention is that even when brake pads having the same coefficient of friction are used, the difference between the initial coefficient of friction and that after a considerable number of times of use is small, a large brake torque can be secured, and the initial parking effectiveness is improved. Is to provide a pad.

The present invention has solved the above problems by the following means.
(1) A brake pad in which a tapered portion is formed on a friction surface of a friction material composed of at least a base fiber, a binder, and a filler, and the friction surface on the inner peripheral side of the contact position of the friction surface with the rotor A brake pad that occupies 1/3 to 1/2 of the surface area and has a taper portion with a depth of 0.05 to 0.5 mm.
(2) The brake pad according to (1), wherein the taper portion has a depth of 0.1 to 0.25 mm.

By providing a wide taper on the inner circumference side of the brake pad, the contact position between the friction material and the rotor is closer to the outer circumference, the initial effective brake diameter is increased, and the brake torque is increased even with the same friction coefficient. Efficacy up is possible. Further, by making the depth of the taper portion as shallow as 0.5 mm or less, it was possible to hit the entire surface at an early stage of use.
In the case where the taper amount is 0.15 mm, the entire surface can be obtained by using at least about 100 times.

The brake pad according to the present invention is characterized by a taper portion having an area ratio of 1/3 to 1/2 with respect to the entire friction surface on the inner peripheral side of the contact position with the rotor, and a depth of 0.05 to 0.5 mm. Is formed. This area ratio is considerably larger than the conventional product. The shape of the taper portion 3 provided on the inner peripheral side of the rotor may be a straight belt shape or a curved shape with a bulging center portion as shown in FIGS. 1 (a) and 1 (b). It is only an example and is not specified.
The feature is most easily shown by the cross section of the pad 2. 2 (a), (b), and (c) of FIG. 2 are exaggerated to show the taper portion, but the cross section of the pad may be linear, curved, or stepped. It is not limited.

  The taper amount of the brake pad of the present invention is preferably 1/3 to 1/2 in terms of area ratio with respect to the entire friction surface, and the depth is preferably 0.5 mm or less. When the taper amount area ratio exceeds 1/2, the contact area with the rotor is reduced and the potency is reduced. Further, when the taper amount is less than 1/3, the change in effective diameter is small, and the expected effect cannot be obtained. Moreover, about the depth of a taper part, it is 0.05-0.5 mm, More preferably, it can be set to the normal whole surface in the initial stage of use by setting it as 0.1-0.25 mm. For example, in the case of a taper depth of 0.15 mm, the entire surface can be hit by using at least about 100 times, and normally the entire surface can be hit by using about 20 times.

The friction material used for the brake pad of the present invention is a reinforcing fiber, a binding material, a friction adjusting material or the like as a base material that is usually used.
Reinforcing fibers that are the base material of the friction material include metal fibers such as steel fibers, copper fibers, and brass fibers; aromatic polyamide fibers (aramid pulp, etc .: commercially available products such as DuPont's brand name Kevlar), acrylic Examples thereof include organic fibers such as fibers, cellulose fibers, and flame-resistant acrylic fibers; non-asbestos inorganic fibers such as potassium titanate fibers, glass fibers, alumina fibers, carbon fibers, and rock wool. One or a combination of two or more of these can be used.

Examples of the binder include thermosetting resins such as phenol resins, urea resins, melamine resins, or modified resins thereof.
Examples of friction modifiers include organic dust such as cashew dust, rubber dust, and melamine dust; fillers (fillers) such as calcium carbonate, barium sulfate, layered clay mineral, and calcium hydroxide; metal oxides such as magnesia, alumina, and zirconia Such as aluminum powder, copper powder, zinc powder and other metal powders, graphite, molybdenum disulfide and other lubricants, etc. Can be used as a material.

  The manufacturing process of the friction material is formed into a predetermined shape by a sheet metal press in the same manner as in the conventional method, subjected to degreasing treatment and primer treatment, and a pressure plate coated with an adhesive, heat resistant organic fibers and metal fibers. Etc. and powder raw materials such as inorganic / organic fillers, friction modifiers and thermosetting resin binders, etc., and agitation using a mixer such as Henschel mixer, Redige mixer, Eirich mixer A preform formed by molding (pre-molding) a sufficiently homogenized raw material at room temperature at a predetermined pressure is thermoformed at a predetermined temperature and pressure in a thermoforming process, and both members are fixed together. After-curing, and finally finishing. At this time, the elastic modulus and the porosity of each layer can be changed by adjusting the formulation according to the target performance of the friction material.

  Hereinafter, the present invention will be described in more detail with reference to specific examples, but the scope of the present invention is not limited to the examples.

Example 1
(Create brake pads)
10% by weight phenolic resin, 10% by weight cashew dust, 20% by weight barium sulfate, 5% by weight zirconia, 5% by weight graphite, 20% by weight copper / aramid (2: 1) fiber, 20% by weight potassium titanate fiber, and A mixture prepared by kneading 10% by weight of alumina / silica ceramic fiber was preliminarily molded by pressing at room temperature and 20 MPa for 1 minute. Next, a friction material preform is set in a thermoforming mold together with a pressure plate (back plate) that has been primed and applied with a phenolic resin adhesive, and thermoformed at a temperature of 40 MPa and 160 ° C. for 10 minutes. did. And heat processing was performed for 120 minutes at 250 degreeC, and the brake pad of size 39 (length) * 72 (width) * 9.5 mm (mold part thickness) was produced.

(Brake pad test)
Table 1 shows the dimensions of the brake members, such as the wheel cylinder, rotor size, and pad area, used for the evaluation of the brake pads.

The friction test was performed under the conditions of the inertial I = 2.5 kg-ms ² and the initial temperature Ti = 50 ° C. by applying the initial effect of the friction pad to a full-size dynamometer. The relationship between the number of times of rubbing and the friction coefficient during parking was obtained. The test results are shown in Table 2. In Table 2, “1/3”, “1/2” and “2/3” of 1/3 taper, 1/2 taper and 2/3 taper represent the area ratio of the taper portion of the pad friction surface. Show.

  From the measurement results of Table 2, the expected friction coefficient change is shown when the area ratio of the tapered portion is 1/3 to 1/2 of the pad friction surface, but the area ratio exceeds 1/2 and 2/3. It was found that the contact area with the rotor was reduced and the friction coefficient was significantly reduced.

  The brake pad according to the present invention can secure a necessary braking force from the initial use stage where it is difficult to exhibit the original performance. Therefore, it is expected to be widely used as a brake pad for industrial machines, passenger cars and the like.

It is a figure which shows the shape of the taper part of the brake pad of this invention. It is a figure which shows the cross section of the brake pad of this invention. It is a figure which shows the plane and cross section of the pad of the prior art example notched in the strip | belt shape along the outer periphery of a brake pad. It is a figure which shows the plane and cross section of the pad of the prior art example notched in the strip | belt shape along the inner periphery of a brake pad.

Explanation of symbols

1 Pressure plate 2 Brake pad 3 Tapered part 4 Notch

Claims (2)

  A brake pad having a tapered portion formed on a friction surface of a friction material composed of at least a base fiber, a binder, and a filler, and having an area of the friction surface on an inner peripheral side of a contact position of the friction surface with the rotor. A brake pad having a taper portion that occupies 1/3 to 1/2 and the taper portion has a depth of 0.05 to 0.5 mm.   The brake pad according to claim 1, wherein a depth of the tapered portion is 0.1 to 0.25 mm.

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