JPH0433470Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a pad for a caliper floating type disc brake, and particularly to a pad that can avoid squealing.

Background of the invention The pad of a disc brake is equipped with a friction material and a back plate to which the friction material is fixed, and is pressed against the disc rotor by a caliper to suppress the rotation of the disc rotor. ,
At this time, an unpleasant noise called squeal may occur.

In order to prevent this squeal, Japanese Utility Model Publication No. 53-45379 discloses that the state of the pad during braking is improved by cutting out a portion of the pad on the rotation center side of the disc rotor and on the leading side. It has been proposed to prevent the occurrence of clipping movements.

However, even with this method, it may not be possible to prevent the occurrence of squealing, and the reality is that a more effective means for preventing squealing generation has been awaited.

The inventor of this invention took into account the fact that squealing is particularly likely to occur when a car is running at a low speed of 20 km/h or less and brakes are applied with a small oil pressure of 10 g/cm ² or less. In a caliper floating type disc brake, we investigated the difference in the way the pads contact the disc rotor when braking is performed with 10 kg/cm ² oil pressure and when braking is performed with 30 kg/cm ² oil pressure. After rubbing the pad against the disc rotor 200 times at an initial braking speed of 65 km/h, a pre-braking rotor temperature of 120°C, and a braking deceleration of 0.35 g, the pads were brought to a near stable state, and the way they contacted the disc rotor was investigated. The results are shown in Figures 6 and 7. In both figures, the shaded part is the part that hit the disc rotor, and the arrows indicate the direction of rotation of the disc rotor. The side is the trailing side and the rear side is the leading side.

When the braking oil pressure is 30 kg/cm ² , the inner pad pressed by the piston in the cylinder part of the caliper is pressed by the piston and the disc rotor, as shown in Figure 6A. As shown in Figure 6B, the outer pad, which is pressed by the reaction pawl of the caliper with almost the entire end far from the center of rotation in contact with it, is in contact with the part of the disk rotor far from the center of rotation, as shown in Figure 6B. There is. On the other hand, when the braking oil pressure is 10 kg/cm ² , the inner pad covers the entire edge of the disc rotor near the rotation center, and the entire circumferential direction of the disc rotor, as shown in Figure 7A. The center part and the edge on the trailing side are in contact with each other, and the outer pad is in contact with the center part in the circumferential direction of the disc rotor and the edge on the side near the rotation center of the disc rotor, as shown in FIG. 7B. The area near the center of the area is hit. Comparing these, the braking oil pressure is 10Kg/cm ²
It can be seen that the parts of the inner and outer pads that contact the disc rotor are almost reversed when pressed with a braking oil pressure of 30 kg/cm ² and when pressed with a braking oil pressure of 30 kg/cm 2 .

It is believed that this phenomenon occurs because the amount of elastic deformation of the pads and calipers differs depending on whether the braking oil pressure is high or low. When the caliper presses the pad against the disc brake, the reaction force causes the caliper to bend, and the distance between the surface that contacts the inner pad of the piston and the surface that contacts the outer pad of the reaction pawl aligns with the center of rotation of the disc rotor. The near side part is wider than the far side part. Therefore, if the thickness of the friction material is the same on the side near and far from the center of rotation of the disk rotor, the surface pressure between the friction material and the disk rotor will be higher on the side far from the center of rotation of the disk rotor. Naturally, the amount of wear increases in this portion. However, if braking is repeated with a constant braking oil pressure, the portion of the disc rotor farther from the center of rotation will wear out, and eventually reach a steady state. That is,
Due to uneven wear of the friction material, unevenness in the distance between the surface that contacts the inner pad of the piston and the surface that contacts the outer pad of the reaction pawl is absorbed, and almost the entire friction surface is evenly pressed against the disc rotor. be. If the braking oil pressure is changed after such a state is reached, the friction material will no longer be in contact with the disc rotor over its entire surface again. If a disc brake that has been adjusted with a braking oil pressure of 30 kg/cm ² is lowered to 10 kg/cm ² , both the inner pad and the outer pad will hit the disc rotor mainly at the part near the center of rotation of the disc rotor. It will become.

Changes in contact are also caused by elastic deformation of the pad. The inner pad is pressed against the disc rotor by the piston coming into contact with the center of its back plate, and the outer pad is pressed against the disc rotor by the bifurcated reaction claws coming into contact with both sides. Since it is impossible to make the back plate so thick that it can be considered an almost completely rigid body, it is unavoidable that the back plate will have some degree of deflection, which will contribute to uneven surface pressure. . In addition, the friction force generated on the friction surface of the friction material is received by the back plate fixed to the surface opposite to the friction surface, but since the friction material has a certain thickness, the friction A rotational moment expressed as the product of the force and the thickness of the friction material is generated, which causes elastic deformation of the friction material and the back plate, resulting in uneven surface pressure. The elastic deformation of these pads increases as the braking oil pressure increases, so for the ^same reason as mentioned above regarding the elastic deformation of the caliper, it is possible to 10Kg/
When a braking oil pressure of cm ² is applied, only the portion of the friction surface with relatively little wear comes into contact with the disc rotor locally.

Braking oil pressure of approximately 30 kg/ ^cm2 is the oil pressure most frequently applied to disc brakes for automobiles, so it is thought that the disc brake in use is in a similar situation to the disc brake after the above-mentioned rubbing. and in this state 10
It is thought that when a relatively low braking oil pressure of less than Kg/cm ² is applied, the inner and outer pads locally hit the disc rotor, causing the squeal.

Therefore, in order to prevent the occurrence of squeaking, it is considered effective to prevent the occurrence of uneven wear itself, which is the cause of the squeaking. The technology described in Publication No. 2433 can be used. This reduces the hardness of the friction material in areas where the contact pressure between the friction material and the disc rotor is high, and conversely increases the hardness in areas where the contact pressure is low, thereby reducing uneven contact pressure. In this way, the occurrence of uneven wear can be prevented, but in this case, special production technology is required to manufacture the friction material, and it is possible to avoid increasing the manufacturing cost of the pads. I don't get it.

Problems to be Solved by the Invention The invention was developed based on the above consideration, and therefore, when the brake is operated with low braking oil pressure, the pads may locally hit the disc rotor. It is an object of the present invention to avoid this problem without increasing the manufacturing cost of the pad.

Means for Solving the Problems The gist of the present invention is to chamfer at least the entire edge of the friction surface of the friction material that is pressed against the disc rotor, at least on the side near the rotation center of the disc rotor. The edge on the leading side and the edge on the side far from the center of rotation of the disc rotor are not chamfered, and it is desirable that the edge on the trailing side of the friction surface of the inner pad is also chamfered.

Function In pads configured in this way, the edge of the friction surface near the center of rotation of the disc rotor is chamfered and removed, so the entire friction surface contacts the disc rotor even when the braking oil pressure is low. It will be easy.

Effects of the Invention As described above, according to the pad of the present invention, even when the braking oil pressure is low, the pad rarely hits the disc rotor locally, and the occurrence of squeal can be effectively suppressed.

Moreover, only the parts that are pressed against the disc rotor when the braking oil pressure is low are chamfered, and the edges on the leading side of the friction surface and the parts that are pressed against the disc rotor when the braking oil pressure is high are chamfered. The edge far from the center of rotation is left intact, so
There is no fear that the braking force will be insufficient due to the reduced friction area.

In addition, since the pad according to the present invention can be formed by simply chamfering the friction material, it does not require special technology to manufacture like the pad proposed in the above-mentioned Japanese Utility Model Publication No. 58-2433. easily, and
It can be manufactured at low cost.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail based on the drawings.

In FIG. 5, 10 is a disk rotor,
An inner pad 14 and an outer pad 16 supported by a support member 12 are disposed on both sides of the disc rotor 10, and a caliper 18 extends over the disc rotor 10, the inner pad 14, and the outer pad 16.
It is disposed so as to be movable in a direction parallel to the rotation center line of 0. Caliper 18 is almost U-shaped,
A cylinder portion 20 is provided in the portion facing the inner pad 14, into which a piston 22 is slidably and fluid-tightly fitted, while a bifurcated reaction claw 2 is provided in the portion facing the outer pad 16.
4 is provided. The inner pad 14 and the outer pad 16 are each made of a metal back plate 2.
Friction materials 30 and 32 are fixed to the inner pads 6 and 28, and when hydraulic pressure is supplied to the cylinder portion 20, the piston 22 moves forward to apply the friction materials 30 of the inner pad 14 to one surface of the disc rotor 10. At the same time, the reaction force causes the caliper 18 to move and the reaction pawl 24 to press the friction material 32 of the outer pad 16 against the other surface of the disc rotor 10, thereby suppressing the rotation of the disc rotor 10.

As shown in FIG. 1, the friction material 30 of the inner pad 14 is divided into two at the center in the circumferential direction of the disc rotor. In the figure, the arrow indicates the rotation direction of the disc rotor 10. Of the two divided friction materials, the friction material on the side facing the arrow is the trailing side part 34, and the friction material on the opposite side is the leading side part 34. 36. Both parts 34 and 36 are chamfered over the entire edge on the side closer to the rotation center of the disk rotor 10 and the entire edge on the trailing side, respectively.
As shown in FIGS. 1 and 2, each of these chamfers has an angle of 45 degrees and a width of 5 mm, and a slope with an inclination angle of 45 degrees is formed in the chamfered portion.

On the other hand, as shown in FIG.
Like the friction material 30, the friction material 32 is divided into two parts, a leading side part 38 and a trailing side part 40, at the center in the circumferential direction of the disc rotor. The entire edge on the rotation center side is chamfered. The chamfers formed on each portion 38 and 40 are so formed that the angle of inclination of the slope formed by the chamfers gradually decreases from the ends of the pad 16 toward the center. Specifically, the line of intersection of this slope with the side surface of the friction material 32 on the rotation center side of the disk rotor is located 5 mm from the friction surface, while the line of intersection with the friction surface is shown in FIG. The pad 16 is inclined away from the center of rotation of the disc rotor 10 as it goes from the end to the center, and the bottom end of the friction material 32 (friction surface when not chamfered) is inclined at the end of the pad 16. The distance from the center of pad 16 is 10 mm.
mm, and the angle of inclination of the slope formed by the chamfer gradually decreases from 45 degrees to just under 30 degrees from the ends of the pad 16 toward the center.

As can be seen by comparing the chamfered portions of the friction materials 30 and 32 with FIG. By chamfering the portion, the tendency for localized contact to occur even when the braking oil pressure is low is reduced, and the occurrence of squeal is effectively avoided.

Also, only the part that comes into contact with the disc rotor 10 when the braking oil pressure is low is chamfered, and the part that comes into contact with the disc rotor 10 when the braking oil pressure is high is left, so braking is performed with a large oil pressure. There is no fear that the braking force will be insufficient in such a case.

In addition, in the above embodiment, both the inner pad and the outer pad were chamfered,
Even if chamfering is applied only to one side, a certain effect can be obtained, and although it is desirable that the edge of the inner pad on the trailing side of the friction material is also chamfered, it is also possible to omit this.

Furthermore, the dimensions of the chamfer are not limited to those described in the above embodiments, and may be determined as appropriate to obtain a good anti-squeal effect. Width is 2.5mm when
It is desirable that the thickness is at least 4 mm, particularly preferably 4 mm or more.

Although not illustrated in detail, the present invention can be implemented in various modifications and improvements based on the knowledge of those skilled in the art.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an inner pad according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken from FIG. 1. FIG. 3 is a front view showing an outer pad according to an embodiment of the present invention, and FIG. 4 is a sectional view taken along the line "--" in FIG. FIG. 5 is a side sectional view showing the main parts of the disc brake equipped with the inner pad and outer pad. FIGS. 6A and 6B are diagrams showing the portions of the conventional inner pad and outer pad that contact the disc rotor when each is pressed with a braking oil pressure of 30 kg/cm ² . Figures 7A and B show that the conventional inner and outer pads each have a braking pressure of 10Kg/
FIG. 3 is a diagram showing the portion that hits the disc rotor when pressed by cm ² . 10... Disc rotor, 14... Inner pad, 16... Outer pad, 18... Caliper,
26, 28... Back plate, 30, 32... Friction material.

Claims (1)

[Claims for Utility Model Registration] (1) A disc brake that includes a friction material and a back plate to which the friction material is fixed, and that suppresses rotation of the disc rotor by being pressed against the disc rotor by a floating caliper. In the pad, at least the entire edge of the friction surface of the friction material that is pressed against the disc rotor near the center of rotation of the disc rotor is chamfered, and at least the edge on the leading side and the part far from the center of rotation of the disc rotor are chamfered. A disc brake anti-squeal pad featuring no chamfers on the side edges. (2) The anti-squeal pad according to claim 1, wherein the pad is an inner pad, and the chamfer is also applied to an edge on the trailing side of the friction surface.