JPH11117969A - Brake pads and disc brakes - Google Patents

Abstract

(57) Abstract: A disk brake provided with a brake pad suitable for a ventilation type disk rotor is provided. A groove (76) extending in the radial direction and increasing in width toward the inner circumferential side of the rotor is formed in a circumferential central portion of a friction material (72) of a brake pad. , A second friction material 80 are provided. Further, both side edges 82 and 84 of the friction material 72 separated in the rotor circumferential direction are
Inclined with respect to the radial direction of the disk rotor 30,
They are almost parallel to each other. Therefore, the friction material 72
The side edges 82 and 84 and the groove 76 of the disk rotor 30
The fins 48 are not parallel to each other, and the occurrence of squeal during braking is suppressed. Further, the rotor inner peripheral edges 94 and 96 of the first and second friction materials 78 and 80 are shorter than the rotor outer peripheral edges 90 and 92, and the friction material 72 has an area on the side that contacts the outer peripheral portion of the disk rotor 30. Since the area of the friction member 72 is larger than the area of the friction member 72, the uneven wear of the friction member 72 is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art A brake pad includes a friction material and a back plate fixed to the back surface thereof, and is pressed against an annular friction surface of a disk rotor to suppress the rotation of the disk rotor. Conventionally, in such a brake pad, a groove extending in the radial direction of the rotor has been formed at the center of the friction material in the circumferential direction of the rotor. The groove may be formed to penetrate the friction material in the thickness direction, or may be formed to leave a portion adjacent to the back plate. In any case, by forming the groove, it is possible to suppress the occurrence of cracks in the friction material and the occurrence of water fade in which water enters between the friction material and the disk rotor and the friction coefficient decreases. it can.

Assuming that the area of the friction material in contact with the inner peripheral portion of the rotor and the portion in contact with the outer peripheral portion of the rotor are the same and that the pressing force is the same, the peripheral speed of the disk rotor is higher on the outer peripheral side. As a result, the portion in contact with the outer peripheral portion of the rotor wears more. For this reason, as described in Japanese Utility Model Application Laid-Open No. 54-15677, the area of the portion of the friction material that contacts the outer peripheral portion of the rotor is made larger than the area of the portion that contacts the inner peripheral portion of the rotor. That is being done. However, it is difficult for the fan-shaped brake pads to be properly supported by the supporting device. Thus, as described in Japanese Utility Model Publication No. 4-33470, both side edges of the brake pad are often parallel to or close to each other. However, in this type of brake pad, a friction material is used. It is inevitable that the area of the portion which comes into contact with the outer peripheral portion of the rotor tends to be insufficient.

When a fan-shaped brake pad is used when a ventilation type disk rotor is used as a disk rotor, a phenomenon called brake squeal, in which abnormal noise having a high frequency occurs during braking, is likely to occur. After examining the cause, the following was found. In the ventilation type disk rotor, two disks are connected by a plurality of fins extending in the radial direction of the disks, and a ventilation path extending in the radial direction is formed between the two disks and the fins. Since both outer surfaces of the portion where the ventilation path is formed are annular friction surfaces, the portions of both disks that are not supported by the fins are inward when the brake pads are pressed against the friction surfaces. (Ventilation path side), the friction surface is likely to bend, and the friction surface has a wavy shape composed of peaks and valleys extending in the radial direction. On the other hand, in the fan-shaped brake pad, since both side edges of the friction material are parallel to the peaks and valleys, it is presumed that brake vibration is likely to occur and squeal is likely to occur.

[0005]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides a friction material which is in contact with the outer peripheral portion of the rotor while both side edges are parallel to or close to each other. The purpose of the present invention is to obtain a brake pad that does not have a shortage of the area of the portion to be made, and to obtain a disk brake having a ventilation type disk rotor that does not easily generate squeal. According to the present invention, the following brake pads and disc brakes can be obtained. As in the case of the claims, each aspect is divided into sections, each section is numbered, and if necessary, the other sections are cited in a form in which the numbers are cited. This is to clarify the possibility of combining the features described in each section. (1) A brake pad including a friction material and a back plate fixed to the back surface thereof, the brake pad being pressed by an annular friction surface of the disk rotor to suppress the rotation of the disk rotor, wherein both end portions of the friction material are provided. The angle formed by each of the edges with respect to the center line of the brake pad is smaller than the angle formed by each straight line passing through each end point on both sides of the inner peripheral side of the rotor and the center of the rotor with the center line, and A groove extending in the radial direction of the rotor and having a width increasing toward the side corresponding to the inner peripheral portion of the rotor is formed at an intermediate portion in the rotor circumferential direction of the material, so that the friction material has a groove on the side in contact with the inner peripheral portion of the rotor. A brake pad wherein the sum of the lengths of the portions in the circumferential direction of the rotor is shorter than the sum of the lengths of the portions in the circumferential direction of the rotor that are in contact with the outer peripheral portion of the rotor. In this way, if a groove is formed in the intermediate portion of the friction material in the rotor circumferential direction, the groove extending in the radial direction of the rotor and having a width increasing toward the side corresponding to the inner circumferential portion of the rotor, so that both side edges of the friction material are parallel to each other or While maintaining a state close to that, while enjoying the advantage of the ease of supporting the brake pad by the support device, the area of the portion of the friction material contacting the outer periphery of the rotor and the area of the friction material contacting the inner periphery of the rotor And the ratio can be made appropriate. For example, the ratio of the sum of the length in the circumferential direction of the rotor on the side in contact with the outer peripheral portion of the rotor to the sum of the lengths in the circumferential direction of the portion in contact with the inner peripheral portion of the rotor, Making the ratio of the radius to the radius to the inner periphery of the rotor substantially equal, that is, the ratio of the former to the latter is in the range of 0.7 to 1.3, preferably 0.8 to 1.2, and more preferably 0.8 to 1.2; Desirably 0.9 ~
1.1. (2) The groove is located at the center of the friction material in the circumferential direction of the rotor.
The brake pad according to the item (1), which has been formed. It is also possible to form two or more grooves at a distance in the circumferential direction of the rotor, and it is desirable to suppress the occurrence of water fade and cracks. It is desirable to provide one for each. (3) The ratio of the sum of the length of the rotor inner peripheral edge of the friction material to the sum of the length of the rotor outer peripheral edge is substantially the ratio of the radius of the rotor inner peripheral edge to the radius of the rotor outer peripheral edge. Equals (1) or
The brake pad according to the item (2). With this configuration, the relationship between the area of the portion that contacts the outer peripheral portion of the rotor and the area of the portion that contacts the inner peripheral portion of the rotor can be made the same as that of the fan-shaped brake pad. (4) The two disks are connected by a plurality of fins extending in the radial direction of the disks, and a ventilation path extending in the radial direction is formed between the two disks and the fins. The outer surface of the formed portion includes a ventilation type disk rotor having an annular friction surface, a friction material and a back plate fixed to the back surface thereof, and is pressed against the friction surface of the disk rotor. A brake pad for suppressing rotation of a disk rotor, wherein an angle formed by each of both side edges of the friction material with respect to a center line of the brake pad is defined by each end point of the both side edges on the rotor inner peripheral side and the rotor center. And a groove extending in the radial direction of the rotor and having a width that is larger on the side corresponding to the inner circumferential portion of the rotor, at an intermediate portion of the friction material in the circumferential direction of the rotor. To be formed A brake pad in which the sum of the lengths of the friction material on the side in contact with the inner peripheral portion of the rotor in the rotor circumferential direction is shorter than the sum of the lengths in the circumferential direction of the rotor on the side contacting the outer peripheral portion of the rotor; A torque receiving member that supports the brake pad so as to be able to approach and separate from the friction surface of the disk rotor and receives a co-rotating torque applied to the brake pad from the disk rotor; and a pressing device that presses the brake pad against the disk rotor. Disc brake including (claim 2). In this disc brake, (1)
In addition to the effects and effects described in relation to the brake pad in the section, the effect of suppressing the generation of squeal is obtained. The reason is that the groove extending in the radial direction of the rotor becomes wider toward the side corresponding to the inner peripheral portion of the rotor, which means that the edge of the friction material defining the groove is inclined with respect to the radial direction of the rotor. That is, since the edge of the friction material and the wavy peaks and valleys are not parallel to each other, but intersect, the brake vibration is less likely to occur as compared to the case where they are parallel, and squealing is generated. Is supposed to be suppressed well. Further, the angle formed by each of the two side edges of the friction material with respect to the center line of the brake pad is the angle formed by each straight line passing through each end point of the both side edges on the inner circumferential side of the rotor and the center of the rotor with the center line. It is presumed that since both sides are not parallel to the wavy peaks and valleys of the rotor because they are smaller than the peaks and valleys, the generation of squeal is suppressed as in the case described above.
Whether or not these assumptions are correct should be clarified in future studies, but experiments have confirmed that the effect of suppressing squealing can be obtained. In addition, in order to suppress squeal, the edge of the friction material defining the groove and the wavy peak,
The larger the angle formed with the valley, the better. From this viewpoint, it is desirable that one groove is formed at the center of the friction material in the circumferential direction of the rotor.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a vehicle disk brake will be described below in detail with reference to the drawings. In FIG. 1, reference numeral 10 denotes a steering knuckle, which is supported by a vehicle body (not shown) via a strut 14 and a lower ball joint 16 so as to be rotatable around an axis inclined with respect to a vertical axis. The steering knuckle 10 rotatably supports a spindle 22 and an axle hub 24 via a bearing 18 and a seal 20. Also, the fitting portion 26 of the axle hub 24
A flange portion 28 extends outward in the radial direction. The flange portion 28 is provided slightly inside the tip end (outside end of the vehicle) of the fitting portion 26, and
0 is fixed.

The disk rotor 30 is made of an aluminum alloy containing aluminum as a main component, and is extended radially outward from a bottomed cylindrical hat portion 36 and a cylindrical portion 38 of the hat portion 36. And an annular friction plate portion 40. The bottom portion of the hat portion 36 is fitted to a portion of the fitting portion 26 of the axle hub 24 on the tip side from the flange portion 28, and is formed by a plurality of (only one of which is shown in FIG. 1) bolts 42 and a nut (not shown). The flange 28 and the hat 36 are fastened. The axle hub 24 is also mounted on the disk rotor 3 by bolts 42.
A disc wheel (not shown) is concentrically fixed to the outside of 0.

The disk rotor 30 is of a ventilated type, and has two disks 44,
The opposing inner side surfaces of the disks 46 are connected by a plurality of fins 48 extending in the radial direction of the disks 44, 46, and a ventilation path 50 extending in the radial direction is formed between the disks 44, 46 and the fins 48. ing. Outer surfaces of the disks 44 and 46 opposite to the inner surfaces where the ventilation passages 50 are formed are friction surfaces 52 and 54, respectively.

An inner pad 60 and an outer pad 62 are supported on a mounting bracket 64 on both sides of the friction plate 40, respectively. The inner pad 60 is moved by a hydraulic cylinder 66 to the friction plate 40 of the disk rotor 30. The outer pad 62 is brought into frictional contact with the friction surface 54 of the friction plate portion 40 on the outside of the vehicle by causing the caliper 70 to move by the reaction force of the frictional surface 52 on the vehicle inner side. Suppress.

The inner and outer pads 60 and 62 have a friction material 72 opposed to the friction surfaces 52 and 54, respectively, and a steel plate back plate 74 fixed to the back surface of the friction material 72 and holding the friction material 72 from the back side. It has. As shown in FIG. 2, the friction material 72 has a groove 76 extending radially at the center in the rotor circumferential direction and penetrating in the thickness direction of the friction material 72. , The center line of the pads 60 and 62 (the disk rotor 30
Of the first friction member 78 and the second friction member 80 provided symmetrically with respect to the radial direction of the first friction member. Friction material 72
Side edges 82, 84 (side edges of the first and second friction members 78, 80 on the side separated from each other) are pads 60, 84, respectively.
The set angles θ ₁ and θ _{4 are} inclined with respect to the center line of 62, and these set angles θ ₁ and θ ₄ are
By setting each straight line (each shown by a thin line) extending in the radial direction through each end point A, B on the inner peripheral side of the rotor to be smaller than the angle formed by the center line of the pad, it becomes nearly parallel to each other. ing. The side edges 86, 88 of the first and second friction members 78, 80 on the side close to each other are inclined by the set angles θ ₂ , θ _{3 with} respect to the center line of the pad, and these side edges 86, 88. Thereby, the above-mentioned groove 76 whose width becomes wider toward the inner circumferential side of the rotor is defined.

Also, the radius of the first and second friction members 78, 80
Rotor outer side edges 90 and 92 and rotor inner circumference
The side edges 94 and 96 have a generally arc shape. here
The radius of the outer peripheral edge of the friction material 72 is R,
The radius of the peripheral edge is represented by r, and the outer peripheral side of the rotor of the first friction material 78
L is the length of edge 90₁ , The length of the rotor inner peripheral side edge 94 is l
₁ , The length of the rotor outer peripheral edge 92 of the second friction material 80 is L
_Two , The length of the rotor inner peripheral side edge 96 is l_Two Then, this implementation
Outer periphery of first and second friction members 78 and 80 in the form
The lengths in the circumferential direction on the inner and inner peripheral sides are given by the following equations.
It is set to stand up. L₁ + L_Two / L₁ + L_Two = R / r (1) L₁ / L₁ = L_Two / L_Two = R / r (2) As is apparent from the above equation (1), the first and second friction members 7
The sum of the lengths of the rotor outer peripheral edges 90
The ratio of the sum of the lengths of the inner side edges 94 and 96 to the friction material 72
Of the radius of the rotor outer peripheral edge to the rotor inner peripheral edge radius
And, as is apparent from the above equation (2).
The outer peripheral side edge 9 of each of the first and second friction members 78 and 80
0, 92 and the ratio of the rotor inner peripheral side edges 94, 96 are also
Of the outer peripheral edge of the rotor of the friction material 72 and the inner peripheral edge of the rotor
With the radius of Therefore, the friction material 72
Is that the length of the inner peripheral side edge of the entire friction material 72 is outside the rotor.
It is shorter than the length of the peripheral edge, and the area on the rotor
It is almost fan-shaped and larger than the area on the inner circumference side of the
Similarly, each of the first and second friction materials 78 and 80 is also low.
The area on the outer circumference is larger than the area on the inner circumference.
Will be done. In addition, as an example of a specific numerical value,
R = 150mm, r = 100mm, L₁ = L _Two = 60mm, l
₁ = L_Two = 40 mm.

In the disk brake constructed as described above, both side edges 82 and 84 of the friction material 72 and the groove 76 are provided.
Are inclined with respect to the radial direction of the disk rotor 30, that is, the direction in which the fins 48 and the ventilation passages 50 extend, so that the occurrence of brake squeal can be suppressed. The formation of the groove 76 allows the area of the portion of the friction material 72 that contacts the outer peripheral portion of the disk rotor 30 to be larger than the portion that contacts the inner peripheral portion. The outer peripheral portion can be received by the wider surface of the friction material 72, and uneven wear of the friction material 72 in the rotor radial direction is reduced. In this embodiment, the mounting bracket 64 constitutes a torque receiving member, and the caliper 70 having the hydraulic cylinder 66 constitutes a pressing device.

The two side edges 82 and 84 of the friction material 72 in the above embodiment can be parallel to each other like a conventional brake pad. In this case, the inclination angle of both side edges with respect to the rotor radial direction can be increased,
Although it is desirable in terms of suppressing noise, the area of the friction material on the outer peripheral side of the rotor is reduced relative to the area on the inner peripheral side of the rotor. Therefore, in order to maintain the relation of the above-described formula (1) in the above embodiment, if the width of the groove formed in the friction material is made wider toward the inner circumferential side of the rotor than the groove 76, the outer circumference of the rotor of the friction material is It can be avoided that the area of the side becomes short.

The groove 76 in the above embodiment is provided with the friction material 7
2 is formed so as to penetrate in the thickness direction, but it is also possible to form a similar groove while leaving a portion of the friction material adjacent to the back plate. In addition, without departing from the scope of the claims, the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art.

[Brief description of the drawings]

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

FIG. 2 is a side view showing a brake pad of the disc brake together with a disc rotor.

[Explanation of symbols]

30: Disk rotor 44, 46: Disk 48:
Fin 50: Ventilation path 52, 54: Friction surface 60: Inner pad 62:
Outer pad 64: Mounting bracket
70: Caliper 72: Friction material 74: Back plate 7
6: groove 82, 84: side edge 90, 92: rotor outer edge 94, 96: rotor inner edge

Claims (2)

[Claims] 1. A brake pad including a friction material and a back plate fixed to a back surface thereof, the brake pad being pressed by an annular friction surface of a disk rotor to suppress rotation of the disk rotor, The angle formed by each of both side edges with respect to the center line of the brake pad is smaller than the angle formed by each straight line passing through each end point of the both side edges on the rotor inner peripheral side and the center of the rotor, and A groove is formed at an intermediate portion of the friction material in the rotor circumferential direction, the groove extending in the radial direction of the rotor and being wider on a side corresponding to the rotor inner peripheral portion, so that the friction material contacts the rotor inner peripheral portion. A brake pad in which the sum of the lengths of the portions on the side in the rotor circumferential direction is shorter than the sum of the lengths of the portions on the side in contact with the outer periphery of the rotor in the rotor circumferential direction. 2. The two disks are connected by a plurality of fins extending in the radial direction of the disks, and a ventilation path extending in the radial direction is formed between the two disks and the fins. A ventilation type disk rotor in which both outer surfaces of a portion where a path is formed is an annular friction surface, and a friction material and a back plate fixed to the back surface thereof are pressed by the friction surface of the disk rotor. A brake pad for suppressing the rotation of the disk rotor, wherein an angle formed by each of both side edges of the friction material with respect to a center line of the brake pad is defined by each end point of the both side edges on the rotor inner peripheral side. Each straight line passing through the center of the rotor is smaller than the angle formed with the center line, and extends in the radial direction of the rotor at an intermediate portion of the friction material in the circumferential direction of the rotor, and the width increases toward the side corresponding to the inner circumferential portion of the rotor. A groove is formed Thereby, a brake pad in which the sum of the lengths in the rotor circumferential direction of the portion of the friction material that contacts the inner peripheral portion of the rotor is shorter than the sum of the lengths of the rotor in the circumferential direction on the side that contacts the outer peripheral portion of the rotor, A torque receiving member that supports the brake pad so that it can approach and separate from the friction surface of the disk rotor and receives a co-rotating torque applied to the brake pad from the disk rotor; and a pressing device that presses the brake pad against the disk rotor. Including disc brakes.