JPH09151970A - Shim for disc brake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the heat transfer to a brake piston in braking, and relatively uniform the pressing force of the brake piston acting on the back plate of a friction pad. SOLUTION: A shim 14 is mounted on the back surface of the back plate of a friction pad, and the piston of a hydraulic device makes contact with ring-like contact parts 38, 40, 42. These contact parts have a plurality of slots 44 formed thereon, so that air can be carried in the contact parts through the slots, when a piston contacts it, to cool the shim 14 and the piston. Each slot 44 is formed in parallel to an air flow 58, or along the tangential, direction of a rotor in the rotor circumferential central section of the shim 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc brake shim arranged between a back metal of a friction pad of a disc brake and a brake piston which presses the friction pad against a rotor.

[0002]

2. Description of the Related Art Generally, a disc brake is designed so that a piston of a hydraulic device provided on a caliper body presses a friction pad against a rotating rotor to generate a braking force. However, since the friction pad is pressed against the rotor that is rotating at high speed, a high temperature occurs due to friction between the friction material of the friction pad and the rotor. It is transmitted to the brake fluid and raises the temperature of the brake fluid.

Therefore, the heat transfer from the friction pad to the piston is reduced by interposing a member having a low thermal conductivity between the pad back metal and the piston or spraying ceramic on the back metal. ing. Further, in order to prevent a squeaking noise caused by relative movement between the back metal and the piston when the brake is actuated, so-called "squeaking", a portion of the shim interposed between the back metal and the piston, which the piston abuts. It has been proposed that a plurality of circular holes are provided in the piston to cool the air so that air flows to the piston abutting portion, and that the contact area of the piston is reduced to suppress heat transfer to the piston (actual exploitation 55. -45089).

[0004]

By the way, in the vicinity of the friction pad, the surrounding air is dragged by the rotation of the rotor and flows in almost one direction. Therefore, when the circular hole is formed, the projected length of the air flow path in the direction of the air flow is small, and a sufficient cooling effect by the air flow cannot be obtained.
The rise in brake fluid temperature cannot be suppressed sufficiently. Then, in order to obtain a sufficient cooling effect, when it is attempted to increase the projected length of the air flow path of the piston abutting portion in the direction of the air flow, some circular holes must be made considerably large. FIG. 5 is an explanatory diagram thereof.

In FIG. 5, a ring-shaped portion 10 indicated by a chain double-dashed line is a contact portion of a brake piston (not shown) with a shim 14 attached to the back surface of the friction pad backing plate 12. Further, the rotor (not shown) rotates in the clockwise direction in FIG. 5, and the air flows laterally from the left to the right in the figure as indicated by arrow 16. The shim 14 has a piston contact portion 1
0 circular holes for cooling are formed symmetrically in the horizontal direction and the vertical direction in the drawing. Piston tip outer diameter D that abuts shim 14
Is about 54 mm, an air passage for cooling is formed in the abutting portion 14 by a circular hole, and when the projected length of the air passage in the direction of the air flow 16 is 25 mm,
The sum of the projected length a of the air passage formed by the upper and lower circular holes 18 and 20 and the projected length b of the air passage formed by the central circular hole 22 is set to 25 mm. That is,

## EQU1 ## 2a + b = 25 mm.

By the way, the projected length a of the upper and lower circular holes 18 and 20 is such that the contact portion 10 at that portion has a flow of air 16
Since it is almost parallel to, the required projection length cannot be obtained even if a considerably large circular hole is formed. Therefore, in order to obtain the required projected length of the air passage, it is necessary to ensure by the projected length b formed by the central circular hole 22. However, in order to ensure the required projected length, the central circular hole 22 must be made quite large. For example, assuming that the projected length a of the air passage formed by the upper and lower circular holes 18 and 20 is 2.5 mm, the projected length formed by the circular hole 22 in the center is 2 mm.
Must be 0 mm. For this reason, the pressing force of the piston does not uniformly act on the pad backing metal 12, and the friction material of the friction pad is unevenly worn, which causes abnormal noise during braking.

The present invention has been made to solve the above-mentioned drawbacks of the prior art. The heat transfer to the brake piston during braking can be reduced, and the pressing force of the brake piston acting on the back metal of the friction pad can be reduced. It is an object of the present invention to provide a disc brake shim that can be made relatively uniform.

[0008]

In order to achieve the above object, the first of the disc brake shims according to the present invention comprises:
A shim arranged between a back metal of a friction pad and a brake piston, wherein a plurality of elongated holes along the direction of air flow of the friction pad portion are provided at a contact portion of the brake piston. Is formed so as not to exceed the center line of the contact portion of the brake piston which is orthogonal to the elongated hole. When the brake piston abuts at a plurality of positions in the rotor circumferential direction, a plurality of elongated holes may be formed in each abutting portion, and these elongated holes may be parallel to the tangential direction of the rotor at the center between the abutting portions. However, it may be parallel to the tangential direction of the rotor. Further, a plurality of elongated holes can be formed in the radial direction of the rotor. In this case, the elongated holes at both ends in the radial direction of the rotor can be made longer than the elongated holes between them, and each elongated hole can have the same width.

[0009]

According to the present invention constructed as described above, by forming the elongated holes along the direction of air flow, the projected length of the air passage in the contact portion of the brake piston in the direction of air flow can be reduced. It is possible to match the width of the long holes, and it is possible to form a plurality of air channels having a uniform width. Then, it becomes possible to arrange a plurality of elongated holes of the same width at equal intervals in a direction orthogonal to the direction of air flow, and it is necessary to provide a necessary direction in the direction of air flow of the air passage formed in the piston contact portion. The projection length can be easily secured, the cooling effect of the piston can be enhanced, and the pressing force of the brake piston that acts on the backing plate of the friction pad can be made almost uniform, resulting in friction of the friction pad. Uneven wear of the material can be eliminated, and generation of abnormal noise during braking can be prevented. Also, by forming each long hole so that it does not cross the center line of the brake piston contacting part that is orthogonal to the long hole, the long holes can be formed independently on both sides of the center line, and the mechanical strength of the shim can be increased. It is possible to prevent deterioration of durability.

When there are a plurality of contact portions in the circumferential direction of the rotor, the air in the friction pad portion flows substantially in the circumferential direction of the rotor. By forming it in parallel with the tangential direction of the rotor at, it is possible to form an air flow having a large projected length in the direction of the air flow. In particular, a more efficient air flow path can be formed by arranging the elongated hole of each contact portion in the tangential direction of the rotor. If the slots on the outermost and inner sides of the rotor in the radial direction are made longer than the slots between them, even if the slots have the same width, air flow paths will also be formed in the contact parts that are nearly parallel to the slots. It can be reliably formed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a disc brake shim according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a front view of a disc brake shim according to an embodiment of the present invention. Friction pad backing 1
In No. 2, a friction material is provided on the front side facing the rotor 67, and a shim 14 is attached on the back side. In addition, back money 1
2 is formed in a substantially rectangular shape in which the width in the left-right direction of the drawing, which is the circumferential direction of the rotor 67, is wider than the width in the vertical direction of the drawing, which is the radial direction of the rotor 67. The central part of the lower part is cut out in an arc shape. And back metal 1
2 is about 1/1 of the width from the left and right edges of the wide figure.
A pair of circular protrusions 30 are formed at three places, and holes 32 formed in the shim 14 are fitted into the circular protrusions 30 (see FIG. 2).

The shims 14 are formed in a substantially mountain shape so as to extend along the lower cutouts of the back metal 12, and have upper ends at both ends in the rotor circumferential direction (left and right directions in the drawing) and a lower center portion in the rotor circumferential direction (rotor center side). Part) is folded back to the front side of the backing metal 12, and clips 34, 36 are formed on the folding back part. As shown in FIG.
By sandwiching the upper part of the
It can be attached to. And sim 14
In this case, three brake pistons (hereinafter simply referred to as pistons) of a hydraulic device provided in a caliper (not shown) come into contact with ring-shaped contact portions 38, 40, 42 shown by a two-dot chain line. There is. The contact portion 40 is located at the center of the shim 14, and the radial centerline 46 of the rotor 67 coincides with the centerline of the shim 14. Also, the contact portions 38, 42
Are located on both sides of the rotor 67 in the circumferential direction with respect to the contact portion 40 and are line-symmetric with respect to the center line 46.

Further, the shim 14 has abutting portions 38, 4
When a plurality of elongated holes 44 are provided so as to cut a part of 0, 42, an air flow path is formed by these elongated holes 44, and the piston abuts the abutting portions 38, 40, 42. In addition, the air flows through the contact portions 38, 40, 44 through the air flow path. These long holes 44 are
It is formed orthogonal to the center line 46, that is, along the tangential direction of the rotor 67 at the center of the shim 14. And each long hole 44a-44 formed in the contact part 40 of the center.
e is a length that does not exceed the center line 46 in the radial direction of the rotor 67, and five center lines 46 are provided on each side of the center line 46.
It is formed in line symmetry with respect to. Further, the five elongated holes 44 a to 44 e arranged in the radial direction of the rotor 67 have their center positions displaced in the rotor circumferential direction along the contact portion 40, and contact in the rotor tangential direction orthogonal to the center line 46. It is formed symmetrically with respect to the center line 48 of the portion 40, and a central long hole 44c is formed on the center line 48. Further, these elongated holes 44a to 44e have the same radial width d of the rotor 67, and the elongated holes 44a and 44e at both ends in the radial direction of the rotor are the other elongated holes 44b to 44d.
It is formed longer. In the case of the present embodiment, the contact portion 4
0 has an outer diameter of about 54 mm, and the long hole 44 has a width d of 5 m.
m.

The abutting portions 38 and 42 have the same size as the central abutting portion 40, and the long holes 44 formed in the abutting portions 38 and 42 are also the long holes 44 a formed in the abutting portion 40. ~ 44
The same as e. That is, five elongated holes 44 formed in the contact portions 38 and 40 are provided on both sides of the center lines 50 and 52 parallel to the center line 46 of the center contact portion 40.
In addition to being line-symmetric with respect to 0 and 52, center lines 54 and 56 orthogonal to these center lines 50 and 52 are also line-symmetric.

In the shim 14 thus formed,
For example, when the rotor 67 rotates in the clockwise direction in FIG. 1, the air in the friction pad portion flows substantially as indicated by the arrow 58. When the piston abuts the abutting portions 38, 40, 42 of the shim 14 and presses the friction pad against the rotor 67, air is left on the left side of the center lines 50, 46, 52 of the center lines 50, 46, 52. The hot air in the piston flows through the hole 44, and hot air in the piston flows out of the piston through the long hole 44 on the right side of the center lines 50, 46, 52, and the shim 14 and the piston are cooled.

As described above, in the embodiment, the projected length of each elongated hole 44 in the direction of air flow is the same as its width. Therefore, the piston is not in contact with the contact portions 38, 40, 4
When it abuts on 2, the large air passages can be secured by the elongated holes 44, and the air flowing through the air passages cools the shim 14 and the piston, and the contact area of the piston can be reduced. The amount of heat transferred to the brake fluid of the hydraulic device is reduced, and the temperature rise of the brake fluid can be suppressed.

Moreover, since the air passages are formed by the long holes 44, the long holes 44 can be formed at equal intervals along the center lines 50, 46, 52 of the contact portions 38, 40, 42. The pressing force of the piston applied to the friction pad through the shim 14 can be made uniform, uneven wear of the friction material can be prevented, and abnormal noise during braking can be prevented. Further, in the above embodiment, the contact portion 3
The long hole 44 formed along 8, 40 and 42 has the center line 5
Since it is separate on both sides of 0, 46, 52, it is possible to prevent the strength and durability of the shim 14 from being lowered. Further, in the embodiment, since a large cooling effect is obtained, it is possible to use a normal stainless steel plate without using a member having a small thermal conductivity or spraying a ceramic, and it is possible to reduce the cost. it can.

FIG. 4 shows another embodiment. In the shim 14 of this embodiment, the long holes 44 formed in the contact portions 38, 42 located on both sides of the central contact portion 40 are parallel to the tangential direction of the rotor 67 at these contact portions 38, 42. Has been formed. That is, the long holes 44 formed so as to cut the contact portions 38, 42 are parallel to the center lines 64, 66 orthogonal to the center lines 60, 62 of the contact portions 38, 42 in the rotor radial direction. Has been formed. Other configurations are the same as those in the above-described embodiment.

As in this embodiment, the long hole 44 is formed in the rotor 67.
When it is formed along the tangential direction of, the air dragged by the rotation of the rotor 67 can more easily pass through the elongated hole 44, and the cooling effect can be further enhanced.

[0021]

As described above, according to the present invention, since the elongated hole is formed along the air flow direction, the air flow direction of the air flow path in the contact portion of the brake piston is increased. It is possible to match the projected length with the width of the long hole, and it is possible to form a plurality of air channels having a uniform width. Then, it becomes possible to arrange a plurality of elongated holes of the same width at equal intervals in a direction orthogonal to the direction of air flow, and it is necessary to provide a necessary direction in the direction of air flow of the air passage formed in the piston contact portion. The projection length can be easily secured, the cooling effect of the piston can be enhanced, and the pressing force of the brake piston that acts on the backing plate of the friction pad can be made almost uniform, resulting in friction of the friction pad. Uneven wear of the material can be eliminated, and generation of abnormal noise during braking can be prevented. In addition, each long hole is formed so that it does not cross the center line of the brake piston contact part that is orthogonal to the long hole, so that long holes can be formed independently on both sides of the center line, and the mechanical strength of the shim can be increased. It is possible to prevent deterioration of durability.

When there are a plurality of contact portions in the circumferential direction of the rotor, the air in the friction pad portion flows substantially in the circumferential direction of the rotor. By forming it in parallel with the tangential direction of the rotor at, it is possible to form an air flow having a large projected length in the direction of the air flow. In particular, a more efficient air flow path can be formed by arranging the elongated hole of each contact portion in the tangential direction of the rotor. In addition, if the slots on the outermost and inner sides of the rotor in the radial direction are made longer than the slots between them, even if the slots have the same width, the air flow will also flow to the abutting portions that are nearly parallel to the slots. The passage can be formed reliably.

[Brief description of the drawings]

FIG. 1 is a front view of a disc brake shim according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is a front view of a shim according to another embodiment.

FIG. 5 is a diagram illustrating a method of forming an airflow of a conventional disc brake shim.

[Explanation of symbols]

 12 back metal 14 shims 38, 40, 42 contact part 44 long hole 58 air flow

Claims (4)

[Claims] 1. A shim arranged between a backing plate of a friction pad and a brake piston, wherein a plurality of elongated holes along the air flow direction of the friction pad portion are provided at a contact portion of the brake piston. A disc brake shim, characterized in that these elongated holes are formed so as not to exceed a center line of the contact portion of the brake piston orthogonal to the elongated hole. 2. A plurality of abutting portions of the brake piston are present in the circumferential direction of the rotor with which the friction pads are in pressure contact,
The disc brake shim according to claim 1, wherein each of the elongated holes formed in each of the contact portions is parallel to a tangential direction of the rotor at a center between both end contact portions. 3. A plurality of abutting portions of the brake piston are present in the circumferential direction of the rotor with which the friction pads are in pressure contact,
The disc brake shim according to claim 1, wherein each of the elongated holes formed in each of the contact portions is parallel to a tangential direction of the rotor. 4. A plurality of the elongated holes are formed in the radial direction of the rotor, the elongated holes at both ends in the radial direction of the rotor are formed longer than the elongated holes between them, and each elongated hole has the same width. The disc brake shim according to claim 2 or 3, wherein