JPH11148525A - Disc brake pad - Google Patents

Abstract

(57) [Summary] [Object] A frictional material of a disc brake pad of a vehicle disc brake is formed when a brake is operated by forming a heat conductive layer over the entire surface of the friction material of the disc brake pad in contact with the back metal of the disc brake pad. It is an object of the present invention to transmit the generated heat more quickly, suppress deformation of the friction material, suppress local wear, and eliminate brake noise by constantly and stably rubbing the rotor and the friction material. A thermal conductive layer having better thermal conductivity than a base material of the friction material is provided on the entire surface of the disk brake pad in which the friction material contacts the back metal. Accordingly, the heat generated on the friction surface of the friction material surface 21 is quickly transmitted to the back metal 30 via the friction material rear surface 22 to reduce the temperature difference between the friction material front surface 21 and the friction material rear surface 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a disc brake pad mounted on a disc brake device of a vehicle.

[0002]

2. Description of the Related Art Disc brake pads are used in disc brake devices for vehicles. Since the caliper assembly having the disc brake pad is attached to a knuckle or a carrier, the disc brake pad is non-rotatably supported with respect to the vehicle body. On the other hand, the rotor is mounted on wheels and rotates with the wheels when the vehicle is running. Since the disc brake pad is sandwiched from both sides of the rotor, when the disc brake is actuated, it acts to press both sides of the rotor and stop the rotation of the rotor. In this way, the rotation speed of the wheel is reduced or, if necessary, stopped.

At this time, heat is generated at the contact surface due to sliding friction between the rotating rotor and the non-rotating disc brake pad. The friction material used for the disc brake pad becomes high temperature by the generated heat, but the heat is radiated and the temperature goes down when the disc brake is not operated. At high temperatures the friction material expands,
Although there is a repetition of contraction at low temperatures, cracks may occur in the friction material depending on the material of the friction material, the shape of the disc brake pad, and the temperature distribution during operation. Also, the friction material deforms due to the expansion of the friction material at a high temperature, and the slip with the rotor becomes uneven,
In some cases, the frictional material is shaved due to local sliding friction and the contact with the rotor becomes unstable, thereby causing a brake squeal when the disk brake is actuated.

Therefore, for example, Japanese Patent Laid-Open Publication No.
0 "Brake pads for vehicle disc brakes" have been devised. The present invention will be described below by taking a disc brake pad shown in the plan view of FIG. 7 and a disc brake pad shown in the plan view of FIG. 8 as an example.

[0005] The disc brake pad 110 is composed of a back metal 30 having a substantially rectangular shape and a friction material 120 also having a substantially rectangular shape fixed to one surface of the back metal 30. The base material occupying most of the friction material 120 is formed of a resin mold friction material 123, and the whole is made uniform. Pressurized thermoforming is used for fixing the back metal 30. In the first embodiment shown in FIG. 7, the outer peripheral side (upper side in FIG. 7) of the friction material 120 which is in contact with the outer peripheral side of the rotor (not shown) and the right side of FIG. Forming the high carbon friction material 126 having a high content, the resin mold friction material 12
3 and the back metal 3
0.

According to the disk brake pad 110 having such a structure, the heat generated in the friction material 120 by the sliding friction with the rotor is transmitted to the side surface of the friction material 120 using the high carbon friction material 126 as a medium. The temperature difference between the temperature of the friction material 120 on the rotor side and the temperature of the back metal 30 side is suppressed.
The occurrence of cracks on the outer peripheral side of the zero can be prevented.

In the disc brake pad 110a described as the prior art shown in FIG. 8, the high carbon friction material 126a extends over the entire outer peripheral side of the friction material 120a.
Is different from the first embodiment. The operation and the effect are the same as those of the first embodiment, but the high carbon friction material 126a is formed along the four sides on the outer peripheral side of the friction material 120a. Since heat is easily conducted from any outer periphery of the friction member 120a to the back metal 30, cracks can be suppressed over the entire outer periphery of the friction member 120a.

[0008]

In such a conventional disk brake pad, the temperature difference between the surface of the friction material 120 or 120a on the rotor side and the surface on the back metal side is at least the outer peripheral area. Since the portion is reduced, it is possible to surely suppress the occurrence of cracks that have conventionally been likely to occur on the outer peripheral side of the friction material, but the generation of heat cannot be suppressed inside the friction material. Therefore, due to the generated heat, the inside expands and deforms more than the outer peripheral portion, and the surface pressure increases locally between the friction material and the rotor, causing local wear, and as a result, the shape of the friction material The problem is that it creates distortion and creates a cause for brake squeal.

Therefore, in the present invention, the heat generated during the operation of the disc brake is conducted evenly throughout the friction material of the disc brake pad, thereby eliminating local wear of the friction material and preventing brake squeal. The purpose is to:

[0010]

According to a first aspect of the present invention, a friction material of a disc brake pad of a disc brake of a vehicle is provided on a whole surface of a side in contact with a backing of the disc brake pad by a base material of the friction material. Is also provided with a heat conductive layer having good heat conductivity.

According to a second aspect of the present invention, in the disk brake pad according to the first aspect, the mass ratio of graphite contained in the heat conductive layer is substantially equal to the mass ratio of graphite contained in the base material of the friction material. A disc brake pad characterized in that thermal conductivity is improved by a factor of two.

According to a third aspect of the present invention, in the disk brake pad according to the first aspect, the heat conductive layer is formed to be thin at an outer peripheral portion of the friction material and thick at an inner portion thereof. Disc brake pad.

According to a fourth aspect of the present invention, in the disk brake pad according to the first aspect, the heat conductivity of the heat conductive layer inside the friction material is higher than the heat conductivity of the outer peripheral portion. It is a disc brake pad characterized by the following.

[0014]

According to the disk brake pad of the first aspect of the present invention, the friction material of the disk brake pad has good thermal conductivity over the entire surface of the disk brake pad in contact with the back metal. Since the conductive layer is provided, heat generated by sliding friction between the friction material and the rotor is quickly transmitted from the rotor side to the back metal side. Therefore, the temperature difference between the surface of the friction material on the rotor side and the surface on the back metal side can be suppressed to be small. Even when the disc brake is activated, the friction material is prevented from expanding and warping as much as possible. Therefore, the friction material is extremely less likely to be locally worn by the rotor. That is, since a uniform contact surface is secured between the friction material and the rotor, there is an effect that brake squeal does not easily occur, and the object of the present invention is achieved.

According to the disc brake pad of the present invention, the mass ratio of graphite contained in the heat conductive layer is contained in the base material of the friction material. Since the mass ratio of graphite is almost twice as large as that of the mass ratio of graphite having a property of good heat conductivity, better heat conductivity can be obtained, and the friction material warps. The expansion can be suppressed, and the brake squeal can be prevented as described above, thereby achieving the object of the present invention.

According to the third aspect of the present invention, in the disk brake pad according to the first aspect, the heat conductive layer is thin at an outer peripheral portion of the friction material, and is thin at an inner portion. Although it is formed thick, the heat generated when the disc brake is operated has the effect of radiating heat to the atmosphere at the outer peripheral portion of the friction material. Since the conductive layer is thicker, the heat is more quickly transmitted to the back metal inside, so that the temperature distribution of the friction material can be made more uniform, which has the effect of preventing brake squeal as described above. The object of the invention can be achieved.

According to the disc brake pad of the invention described in claim 4, in the disc brake pad according to claim 1, the heat conductivity of the friction material in the heat conduction layer is reduced by the heat conduction of the outer peripheral portion. However, since the heat generated when the disc brake is activated has a heat radiation effect on the outer peripheral portion of the friction material as described above, the temperature tends to be slightly lower than that inside, However, since the heat conduction layer is thicker toward the inside, the heat is more quickly transferred to the back metal inside, so that the temperature distribution of the friction material becomes more uniform, so that the brake There is an effect of preventing squeal, and the object of the present invention can be achieved.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention is directed to a friction material for a disc brake pad, which has better heat conductivity than the base material of the friction material over the entire surface of the disc brake pad in contact with the back metal. Forming a conductive layer. The base material of the friction material is made of resin mold having aramid fiber, graphite or the like. When the mass ratio of graphite contained in the resin mold is increased, the thermal conductivity is improved. Here, a heat conductive layer having good heat conductivity is obtained by approximately doubling the heat conductive layer.

Further, the heat conductive layer may be formed thinner in the outer peripheral portion of the friction material and thicker in the inner portion so that the temperature distribution becomes uniform. Further, the thermal conductivity of the heat conductive layer inside the friction material may be higher than the thermal conductivity of the heat conductive layer in the outer peripheral portion.

A first example of this embodiment will be described with reference to FIG. FIG. 1A is a plan view of the disc brake pad 10 according to the first embodiment, and FIG. 1B is a cross-sectional view thereof. The disc brake pad 10 includes a substantially rectangular back metal 30 and a friction material 20 which substantially covers one surface of the back metal 30 and is also substantially rectangular and fixed. The friction material 20 is composed of a base material 23 constituting a material component thereof, but as shown in FIG. 1B, a heat conductive layer 25 is formed only on the side in contact with the back metal 30. In this embodiment, the thickness is constant.

While the vehicle is running, a rotor not shown in FIG. 1 (shown as rotor 40 in FIG. 6).
However, when the disc brake is operated, the rotor is pressed by the friction material surface 21 of the friction material 20 with the disc brake pad 10 sandwiched from both sides. The braking is performed by stopping the rotation of the rotor.
At this time, frictional heat is generated between the rotor and the friction material 20. Then, the friction material surface 21 is heated to a high temperature, and the heat is transmitted through the friction material 20, transmitted to the friction material back surface 22, which is the surface in contact with the back metal 30, and transmitted to the back metal 30. Accordingly, the temperature of the friction material 20 becomes high, and a temperature difference occurs between the friction material front surface 21 and the friction material rear surface 22.

At this time, in the case of the prior art, the outer periphery of the friction material 120 provided with the high carbon friction material 126 is formed of the high carbon friction material from the front surface to the back surface of the friction material 120. I have. On the other hand, in this embodiment, the friction material surface 21 side in contact with the rotor 40 is the base material 23 of the friction material, and the heat conductive layer 25 is formed on the side in contact with the back metal 30. In the case of the prior art, as described above, since the temperature difference between the front surface and the back surface of the friction material inside the friction material 120 is large, the inside of the friction material 120 is warped as shown in FIG. However, the disc brake pad 10 of the first embodiment
In the above, the heat conductive layer 25 is formed over the entire surface, and the heat of the friction material surface 21 is quickly transmitted from the entire surface of the friction material back surface 22 to the back metal 30 and radiated from the back metal surface 31. The temperature difference between the friction material front surface 21 and the friction material rear surface 22 of the friction material 20 can be kept small over the entire surface. Accordingly, as shown in FIG. 6, even if the friction material 20 presses the rotor 40 to generate heat, the friction material
Since the temperature difference between the friction material 20 and the friction material back surface 22 is small, the amount of deformation when the friction material 20 becomes warped due to thermal expansion is extremely small.

Therefore, the rotor 40 does not locally wear the friction material 20 and a desirable friction state in which the entire surface of the friction material surface 21 is uniformly contacted. When the operation of the disc brake is repeated, even if the friction material 20 once heated to a high temperature is cooled again by heat radiation and then actuated again, local wear does not occur.
As shown in the figure on the right side of the figure, the rotor 40 can uniformly contact the entire surface of the friction material 20. If local wear occurs as in the prior art, non-uniform contact occurs when the disc brake is actuated again, causing brake squeal. However, in the case of the disc brake pad 10 shown in FIG. Since the material 20 uniformly and stably contacts the rotor 40 to cause sliding friction, the occurrence of such brake squeal can be suppressed.

The friction material surface 21 of the friction material 20 when the disc brake is operated with and without the heat conduction layer 25
FIG. 4 shows one of the results of a test on the temperature difference between the friction material and the back surface 22 of the friction material. Similarly, the amount of deformation due to thermal expansion with and without the heat conductive layer 25 is determined by the friction material 2.
FIG. 5 shows the degree of warping of the outer peripheral portion inside the zero. FIG. 4 shows that the present invention can reduce the temperature difference and reduce the amount of deformation by about half, demonstrating a good effect.

Next, a second embodiment is shown in FIG. Although only a cross-sectional view is shown in FIG. 2, a plan view is the same as that of the first embodiment. In this case, the heat conductive layer 25a formed on the side of the friction material 20a in contact with the back metal 30a is formed thin on the outer periphery and thick on the inside. This is different from the first embodiment in that the outer peripheral portion and the inner portion are formed to have the same thickness.

When the disc brake is operated, heat generated by sliding friction between the rotor 40 and the friction material 20a is transmitted to the back metal 31a through the heat conduction layer 25a. The peripheral part has heat radiation to the atmosphere, so the temperature is lower than the inside, so the friction material surface 21
a and the temperature difference between the friction material back surface 22a and the friction material back surface 22a are reduced. Therefore, in the friction material 20a having the configuration as in the second embodiment, the heat conductive layer 25a is formed thicker than the outer peripheral portion in the inside where the temperature difference is likely to be large.
Since the generated heat is quickly transmitted from the outer peripheral portion inside, the temperature difference in the friction material 20a is eventually smaller, and a uniform temperature difference distribution can be obtained as a whole. By such an effect, the effect of reducing brake squeal described in the first embodiment is further exhibited.

A third embodiment is shown in the sectional view of FIG. In this case, the thickness of the heat conductive layer 25b is constant,
b differs from the above two embodiments in that a material having a higher thermal conductivity than the outer peripheral portion 26b is used. In the friction material 20b of the third embodiment, the heat radiation effect is high in the outer peripheral portion as in the second embodiment, and the temperature difference between the front surface and the back surface of the friction material 20b is smaller than that in the interior. , A difference in the thermal conductivity of the heat conductive layer between the inner portion 27b and the outer peripheral portion 26b, so that the inner portion 27b has a higher thermal conductivity than the outer peripheral portion 26b.

Although the above three embodiments have been described, the embodiment of the present invention is directed to transmitting the heat generated by the friction material 20 (20a, 20b) as quickly as possible, and as a result, the friction material surface and the friction material Since the thermal deformation is suppressed by minimizing the temperature difference with the back surface, the heat conductive layer 25 (2
5a, 25b) is not limited to the above-described thickness distribution and the degree of difference in thermal conductivity on a plane, but includes various cases.

[Brief description of the drawings]

FIG. 1A is a plan view of a disc brake pad 10 showing a first example of an embodiment of the present invention, and FIG. 1B is a cross-sectional view of FIG. 1A. .

FIG. 2 is a sectional view of a disc brake pad 10a showing a second example of the embodiment of the present invention.

FIG. 3 is a sectional view of a disc brake pad 10b showing a third example of the embodiment of the present invention.

FIG. 4 is a graph showing an effect of the embodiment of the present invention by a temperature difference between a front surface and a back surface of a friction material.

FIG. 5 is a graph showing the effect of the embodiment of the present invention by the amount of deformation of a friction material.

FIG. 6 is an explanatory diagram illustrating a deformation state of the disc brake pad 10 according to the first embodiment due to heat when the disc brake is operated.

FIG. 7 is a plan view of a conventional disc brake pad 110. FIG.

FIG. 8 is a plan view showing a disc brake pad 110a according to another embodiment of the prior art.

FIG. 9 is an explanatory view showing a state in which the conventional disk brake pad 110 expands, deforms and wears due to heat at the time of braking operation.

[Explanation of symbols]

 10, 110, 110a: Disc brake pad 20, 20a, 20b, 120, 120a: Friction material 21, 21a, 21b: Friction material surface 22, 22a, 22b: Friction material back surface 25, 25a , 25b ... thermal conductive layer 30, 30a, 30b, 130: 130a ... back metal 31, 31a, 31b ... back metal surface 123 ... resin mold friction material 126 ... high carbon friction material

Claims (4)

[Claims] 1. A heat conductive layer having better heat conductivity than a base material of the friction material is provided on the entire surface of the disc brake pad of the vehicle where the friction material of the disc brake pad is in contact with the back metal of the disc brake pad. Disc brake pad characterized by the following. 2. The disc brake pad according to claim 1, wherein the mass ratio of graphite contained in the heat conductive layer is substantially twice as large as the mass ratio of graphite contained in the base material of the friction material, so that thermal conductivity is improved. A disc brake pad characterized by being good. 3. The disc brake pad according to claim 1, wherein the heat conductive layer is formed thinner at an outer peripheral portion of the friction material and thicker at an inner portion thereof. 4. The disc brake pad according to claim 1, wherein a thermal conductivity inside the friction material of the thermal conductive layer is higher than a thermal conductivity at an outer peripheral portion.