JPH0213785Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a disc brake for a vehicle, and in particular, to prevention of uneven wear of friction pads.

Conventional technology Vehicle disc brakes include disc rotors, disc brakes,
It is composed of a friction pad, a pad support device, a pad pressing device, etc. A disk rotor generally has a disk shape, is fixed to a wheel of a vehicle, and rotates together with the wheel. The friction pads are disposed on both sides of the disk rotor, supported by a pad support device so as to be movable in a direction parallel to the rotation axis of the disk rotor, and are pressed against the disk rotor by a pad pressing device. The friction pad consists of a flat friction material and
The friction material is generally compression molded to have uniform hardness. Further, the pad supporting device and the pad pressing device are supported in a cantilevered manner by non-rotating members such as an axle housing and a steering knuckle provided on one side of the disc rotor.

Problems to be Solved by the Invention In the vehicle disc brake of the above configuration, uneven wear of the friction pads is likely to occur, and this uneven wear not only shortens the life of the friction pads, but also reduces the idle stroke of the brake pedal during braking. In order to increase the size of the brake pedal, make the brake pedal feel harder to operate, or promote brake dragging.
Not desirable.

The present invention has been developed with the aim of reducing this uneven wear using the simplest possible means.

Means for Solving the Problems The gist of the present invention is to provide a disc brake for a vehicle that includes the disc rotor, a pair of friction pads, a pad support device, a pad pressing device, and a non-rotating member. Regarding the hardness distribution of at least one of the friction materials in the circumferential direction of the disc rotor, in general parts other than the area near the contact position between the pad pressing device and the backing metal, it is difficult to move the vehicle forward because the pad pressing device is cantilevered. The hardness increases linearly from the end that is strongly pressed against the disc rotor to the end that is weakly pressed by the rotational moment generated in the pad pressing device during internal braking, and the hardness increases linearly near the contact position. Regarding the part, the hardness is non-linearly distributed so that the hardness is lower than the inclined straight line representing the hardness distribution of the general part.

Of the pair of friction pads, the inner pad, which is disposed on the inside of the vehicle body from the disc rotor, that is, on the side where the pad support device and the pad pressing device are supported by the non-rotating member, has a leading end of the friction material, that is, the disc rotor. The wear on the retraction side end is greater than the wear on the trailing end, that is, the wear on the disc rotor retraction side end, and in the outer pad disposed outside the disc rotor, the trailing end of the friction material wears more than the leading end. The amount increases.

Therefore, when applying the present invention to an inner pad, the hardness at the leading end is lower than that at the trailing end, and when applying the present invention to an outer pad, the hardness at the trailing end is lower than at the leading end.

In addition, when the member that contacts and applies pressing force to the friction pad of the pad pressing device is a piston that contacts the center of the friction pad, it is assumed that the back metal is a rigid body due to elastic deformation of the back metal. Compared to the case where the contact pressure at the center of the friction material is higher, the contact pressure at both ends is lower, and when the pressing member is a pair of claws of the reaction part that abuts both ends of the friction pad. , the surface pressure at both ends of the friction material increases, while the surface pressure at the center decreases.

Therefore, when the present invention is applied to a friction pad in which the center part of the back metal is pressed by a piston, the hardness of the center part of the friction material is expressed as a hardness distribution based on the rotational moment generated in the pad pressing device. This means that the friction pad is made lower than the inclined straight line, and the hardness of both ends of the friction pad to which the pressing force is applied by a pair of reaction claws is made lower.

Although it is desirable to apply the present invention to both the inner pad and the outer pad, it is also possible to apply the present invention only to the friction pad on the side where uneven wear is particularly severe.

Function and Effect As mentioned above, if the hardness is uniform, if the hardness of the part where the surface pressure is high is made lower than other parts, the surface pressure will be affected by the rotational moment generated in the pad pressing device and the elastic deformation of the back metal. The effect of reducing uneven pressure and uneven wear can be obtained. Furthermore, since the means for achieving this is simple, that is, changing the hardness of the friction material depending on the location, the cost increase of the disc brake can be minimized.

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

In FIGS. 1 and 2, 2 is a disc rotor, which is fixed to a wheel (not shown) and rotates together with the wheel. An outer pad 6 and an inner pad 8 are arranged on both sides of the disc rotor 2.
These outer pads 6 and inner pads 8 will be collectively referred to as friction pads hereinafter. These friction pads 6 and 8 are supported by a torque member 4 so as to be movable in a direction parallel to the rotation axis of the disk rotor 2. The portion of the torque member 4 on the inside of the vehicle, that is, the portion on the left side of the disc rotor 2 in FIG. The side portions are unsupported and cantilevered. In this embodiment, the torque member 4 constitutes a pad support device.

The friction pads 6, 8 are pressed against the disc rotor 2 by a caliper 10 which is a pad pressing device. The caliper 10 has cylinder parts 12 facing each other.
and a reaction part 14, and a bridge part 16 that connects these parts beyond the outer periphery of the disk rotor 2.
and a disc rotor 2 and a friction pad 6,
It is arranged across 8. Calipa 10
is supported in a cantilevered manner by the torque member 4 in the cylinder portion 12 located inside the vehicle. A pair of slide pins erected on a pair of arm portions 17 extending from the cylinder portion 12 to both sides are slidably inserted into pin holes formed in the torque member 4 in parallel to the rotation axis of the disk rotor 2. By this,
The caliper 10 is supported so as to be movable in a direction parallel to the rotation axis of the disc rotor 2.

The cylinder portion 12 is provided with a cylinder bore 18 that opens toward the disc rotor 2. The cylinder bore 18 has a cylindrical piston 2 with a bottom.
0 is smoothed together. Therefore, as braking fluid pressure is supplied into the cylinder bore 18, the piston 20 is pushed out, the friction pad 8 is pressed against one friction surface of the disc rotor 2, and the reaction force causes the caliper 10 to move. The friction pad 6 is pressed against the other friction surface of the disc rotor 2 by the reaction portion 14.

Here, the friction pads 6 and 8 are the disc rotor 2.
Frictional materials 24, 26 on the side that slides into contact with and a rectangular plate-shaped back metal 2 to which these frictional materials 24, 26 are fixed.
8 and 30, respectively, and the friction material 2
The hardness of 4 and 26 corresponds to uneven surface pressure in the circumferential direction of the disc rotor 2 on the pressing surfaces 22 and 23 of the friction materials 24 and 26 against the disc rotor 2 when the hardness is equal. The areas with high surface pressure are low, and the areas with low surface pressure are high. That is, as shown in FIG. 3, the friction materials 24 and 26 are arranged in the circumferential direction of the disc rotor 2 in the direction of rotation thereof (direction A in FIG. 2).
The friction materials 24, 26 are formed so that their hardness changes with a predetermined hardness distribution.
In response to uneven surface pressure distribution in the circumferential direction of the disc rotor 2 that occurs on the pressing surfaces of the friction materials 24 and 26 due to the structure of the disc brake when the hardness is uniform, Equalize. Predetermined in the pattern.

The friction materials 24 and 26 can be manufactured by the following method. Generally, friction materials 24, 26
The material is a mixture of asbestos, a binder such as resin, rubber, or asphalt, and a filler made of inorganic powder, which is heated and compressed to form the friction material 24, 26 in a predetermined shape. As shown in FIG. 4, for example, the mixture material prepared in advance to have a substantially uniform thickness on the back metal 28 is molded so that the pressed surface has a high hardness portion according to the predetermined hardness distribution. Press mold (upper mold) 3 formed into a curved surface that protrudes downward at the corresponding location
By compressing and heating in step 2, a friction material having a shape that follows the above-mentioned pressing surface is first formed, and then the portion above the dotted line in the figure is cut out so that the surface of the friction material is flat. . The friction material 24 of the friction pad 6 produced by this method is manufactured using the press mold 3.
Since the position corresponding to the downwardly protruding portion of the pressing surface 2 is compressed more strongly, the hardness and density at this position are higher, and the molded product is molded with a hardness in accordance with the predetermined hardness distribution. Incidentally, FIG. 4 shows the state during compression.

Further, the friction materials 24 and 26 can also be manufactured by the method shown in FIG. That is,
For example, the mixture material is prepared on the back metal 28 in such a manner that the thickness increases in areas corresponding to higher hardness parts according to the predetermined hardness distribution, and then a press mold (upper mold) whose pressing surface is parallel to the back metal 28 is prepared. ) 34, compress and heat to the dotted line position in the figure. As a result, the parts corresponding to the thicker parts of the mixture material are more strongly compressed and have higher hardness and density before being compressed, so that a friction material having hardness in accordance with the predetermined hardness distribution is formed. Note that FIG. 5 shows the state before compression.

It should be noted that the friction materials 24 and 26 in FIGS.
The porosity 36 in 4,26 is exaggerated.

The effects of this embodiment will be explained below.

As the brake is operated and brake fluid pressure is supplied into the cylinder bore 18, the friction pads 6 and 8 are pressed against the disc rotor 2 by the reaction portion 14 and the piston 20. At this time,
The reaction portion 14 abuts both ends of the back metal 28 of the friction pad 6 with its two claw-like protrusions, and the piston 20 abuts the center of the back metal 30 of the friction pad 8 at its cylindrical open end. .

When the friction pads 6 and 8 are pressed against the disc rotor 2, a force acts on the friction pads 6 and 8 in a direction that moves them in the direction of rotation of the disc rotor 2. This force is mainly received by the torque member 4, but due to the frictional engagement between the backing metal 28 and the reaction portion 14 and the frictional engagement between the backing metal 30 and the piston 20, the caliper 10
It is also transmitted to As described above, since the torque member 4 and the caliper 10 are supported in a cantilevered manner on one side of the disc rotor 2, when the disc rotor 2 rotates in the direction indicated by arrow A in FIG. A counterclockwise rotational moment will be generated in the member 4 and the caliper 10 in the counterclockwise direction in FIG. Furthermore, since the position where the friction pads 6 and 8 receive force from the disc rotor 2 and the position where the force is received by the torque member 4 are shifted in the direction of the rotation axis of the disc rotor 2, the friction pads 6 and 8 A counterclockwise rotational moment is generated in the friction pad 8, which is clockwise in FIG. On the friction pad 8 side, since the directions of the rotational moment generated in the torque member 4 and caliper 10 and the rotational moment generated in the friction pad 8 itself are the same, the wear of the friction material 26 of the friction pad 8 is caused by the wear of the friction material 26 at the leading end. Larger at ring end. Furthermore, although the directions of both rotational moments are reversed on the friction pad 6 side, since the rotational moment generated in the caliper 10 etc. is larger than the rotational moment generated in the friction pad 6 itself, the friction material 24 of the friction pad 6 ends up The wear is greater at the trailing end than at the leading end.

Further, as described above, when the reaction portion 14 and the piston 20 abut against the friction pads 6 and 8, respectively, the back metals 28 and 30 are elastically deformed and warped. There is a tendency that the center portion of the friction material 26 in the friction pad 8 is pressed more strongly against the both ends of the friction pad 8.

Therefore, if the friction materials 24 and 26 are formed to have uniform hardness, due to the combination of the above factors, the pressing surfaces of the friction materials 24 and 26 will have a sixth hardness.
Nonuniform surface pressure occurs in the circumferential direction of the disc rotor 2 shown in the figure. For this reason, in conventional friction pads that include such friction materials, the parts of the pressing surface with high surface pressure are subject to more wear than the parts with low surface pressure, so as shown by the two-dot chain line in Figure 7, ,
Uneven wear (uneven wear) occurs in the circumferential direction of the disc rotor 2.

However, according to the friction pads 6 and 8 of this embodiment, even when the entire backing metals 28 and 30 cannot be subjected to an even pressing force as described above,
As shown by the solid line in FIG.
The entire disc rotor 6 is subject to wear almost evenly, and uneven wear in the circumferential direction of the disc rotor 2 does not occur.

In other words, the friction materials 24 and 26 in the portions to which a large surface pressure is applied are formed to have low hardness and density, contrary to the magnitude of the surface pressure, so that they are elastically deformed compared to other portions with high hardness and density. Easy to do. Therefore, when the friction pads 6, 8 are pressed against the disc rotor 2, the parts of the friction materials 24, 26, which conventionally had a high surface pressure, are compressed and deformed more easily than other parts. The friction material 24 is not easily deformed due to its high hardness.
26 on the disc rotor 2 is averaged, and localized large wear on the friction materials 24 and 26 is less likely to occur.

In this way, according to this embodiment, the friction material 24,
Since the disk rotor 26 has a hardness pattern that is approximately inversely proportional to the magnitude of the surface pressure applied to the pressing surface, the disk rotor 2
As a result, uneven wear of the friction pads 6 and 8 in the circumferential direction of the disc rotor 2 is almost eliminated.

Although the embodiments of the present invention have been described above based on the drawings, the present invention can also be applied to other aspects.

For example, the caliper 10 in the embodiment described above
is a single-piston type caliper, but even in a double-piston type caliper, it is possible to form friction pads with a hardness distribution that corresponds to the unique structure of the caliper.

Although the friction materials 24 and 26 in the embodiments described above are formed so that their hardness changes continuously in the circumferential direction of the disc rotor 2, they may be formed so that their hardness changes stepwise. That is, as shown in FIG.
is a rectangular parallelepiped-shaped friction material 4 with three types of different hardness.
0, 42, and 44 may be fixed to the back plate 46 at right angles to the circumferential direction of the disc rotor 2, and may have a hardness distribution as shown in FIG.

Furthermore, the material of the friction materials 24 and 26 may be not only a so-called organic lining in which asbestos is bonded with a synthetic resin or the like, but also a so-called inorganic lining made by molding and sintering metal powder.

Further, in the above-described embodiment, the friction materials 24 and 26 whose hardness distribution can equalize the surface pressure are arranged on both sides of the disc rotor 2, but they are used only on one side where uneven wear is likely to occur. It is okay to do so.

The above-mentioned embodiment is merely one embodiment of the present invention, and various modifications may be made to the present invention without departing from the spirit thereof.

As detailed above, according to the present invention, uneven wear in the circumferential direction of the disc rotor does not occur, so shortening the life of the friction pad and increasing the idle stroke during braking is prevented, and the uneven wear of the friction pad is prevented. This has the excellent effect of eliminating the deterioration in braking sensation caused by wear and the dragging of the friction pads.

[Brief explanation of the drawing]

FIG. 1 is a top view of a disc brake that is an embodiment of the present invention. FIG. 2 is a diagram showing the main part of FIG. 1. FIG. 3 is a diagram showing the hardness distribution of the friction pad in the embodiment of FIG. 1. 4 and 5 are diagrams showing a method of manufacturing the friction pad in the embodiment shown in FIG. 1, respectively. FIG. 6 is a diagram showing the surface pressure on the pressing surface of a conventional friction pad. FIG. 7 is a diagram showing the state of wear of the friction pad in the embodiment of FIG. 1. FIGS. 8 and 9 are views corresponding to FIGS. 2 and 3 in other embodiments of the present invention. 2: Disc rotor, 6, 8, 38: Friction pad, 22, 23: Pressing surface, 24, 26, 40, 4
2, 44: Friction material, 28, 30, 46: Back metal.

Claims (1)

[Scope of Utility Model Registration Claim] A disc rotor that rotates together with the wheels of a vehicle, and a pair of friction pads disposed on both sides of the disc rotor, each comprising a friction material and a back metal fixed to the back surface of the friction material. a pad support device that supports the friction pads movably in a direction parallel to the rotation axis of the disc rotor; a pad pressing device that presses the friction pads against the disc rotor; and a pad pressing device that supports the pad pressing device on one side of the disc rotor. In a vehicle disc brake including a non-rotating member supported in a cantilevered manner, the hardness distribution of the friction material of at least one of the pair of friction pads in the circumferential direction of the disc rotor is determined based on the hardness distribution of the friction material of at least one of the pair of friction pads in the circumferential direction of the disc rotor. Regarding the general parts other than the area near the contact position, since the pad pressing device is cantilevered, the end of the pad is strongly pressed against the disc rotor by the rotational moment generated in the pad pressing device when braking while the vehicle is moving forward. The hardness increases linearly as it goes from the edge toward the end of the side that is weakly pressed, and the hardness in the vicinity of the contact position is non-linearly distributed so that it is lower than the inclined straight line representing the hardness distribution of the general area. A vehicle disc brake characterized by: