JPS6124738Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a pad used in a caliper floating type disc brake.

In a caliper floating type disc brake, the caliper, which has a cylinder part into which a piston is fitted and a reaction part formed opposite to the cylinder part, can be moved in a direction parallel to the axis of the disc rotor by means of a support member. This is a type of brake supported by
Hydraulic pressure is applied to the cylinder section, and the piston presses the inner pad against one surface of the disc rotor.The caliper moves due to the reaction force, and as a result, the reaction section presses the outer pad against the other surface of the disc rotor.

It has been known for a long time that this type of brake has the disadvantage that it is prone to fade when the brake is activated while the disc rotor is rotating at a particularly high speed (hereinafter referred to as high-speed braking). .

The inventors of the present invention investigated the cause of this problem and discovered that one of the important causes was uneven contact pressure between the pad and the disc rotor due to the elastic deformation of the caliper. During high-speed braking, high hydraulic pressure is applied to the cylinder section, so the amount of elastic deformation that increases the distance between the cylinder section and the reaction section of the caliper increases, and as a result, the parallelism between the working surface of the piston and the working surface of the reaction section increases. It got worse,
The surface pressure on the outside of the pad (on the outer periphery of the disk rotor) is higher than the surface pressure on the inside. In extreme cases, the inner part of the pad may even separate from the surface of the disc rotor, causing localized fade on the outer part of the pad and reducing braking effectiveness. It is.

Based on the above findings, the present invention has been made with the objective of providing a pad that can minimize unevenness in the surface pressure between the pad and the disc rotor during high-speed braking, thereby reducing the decrease in braking effectiveness.

In order to achieve this objective, the present invention has a plurality of through holes in the back plate of the pad. An arc that is located on the outer side and that the ends of the through holes on the outer circumferential side of the disk rotor are concentric with the circular arc and that pass through the center point of the line segment that connects the center line of the piston and the edge of the friction material on the outer circumferential side of the disk rotor. While the disk rotor is formed to be offset to the outer circumference side so that it is located further outside, no through hole is formed inside the arc passing through the center line of the piston. It is characterized in that the elastic coefficient of compression of the friction material in the outer part is smaller than the elastic coefficient in the inner part of the circular arc.

It has been conventional practice to form several through holes in the back plate of the pad. If a friction material is molded onto such a back plate, the material of the friction material will also flow into the through holes and harden, increasing the adhesion between the two and having the effect of preventing separation between the friction material and the back plate. It is. However, in this case, the through holes are formed almost uniformly over the entire surface of the back plate for that purpose.
The effect of this invention cannot be obtained.

In other words, the reason why the pad according to the present invention is able to reduce the reduction in effectiveness during high-speed braking is that by forming a plurality of through holes only in the outer part of the back plate, the friction of the back plate in this part is reduced. The restraining force on the caliper decreases, and the friction material is apparently more likely to compress and deform in this area. In other words, the elastic modulus of compression becomes substantially smaller, so the elastic deformation of the caliper concentrates on the outer part of the pad. This is because even if a pressing force is applied to the pad, the surface pressure on this part is prevented from becoming extremely high, and instead, the part on the inside of the pad that is difficult to compress and deform acts effectively. If the through-holes are uniformly formed over the entire surface of the friction material, the entire friction material appears to be easily compressed and deformed, and the above-mentioned effect of equalizing the surface pressure cannot be obtained.

In addition, in the pad according to the present invention, it is desirable that the friction material be allowed to flow into the through hole and harden when molding the friction material, since this will increase the adhesion force between the friction material and the back plate. This is not necessarily essential, and the effect of the present invention can be obtained even if the through hole is left empty.

An embodiment of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, a caliper 1 has a substantially saddle shape, including a cylinder portion 3 into which a piston 2 is fitted and a reaction portion 4 formed opposite to the cylinder portion 3. This caliper 1 straddles the disc rotor 5 and an outer pad 6 and an inner pad 7 disposed on both sides of the disc rotor 5, and is supported by a support member 8 via a pair of slide pins (not shown) to support the shaft center of the disc rotor 5. is supported so as to be movable in a direction parallel to .

The outer pad 6 is composed of a friction material 11 that contacts the surface of the disc rotor 5 to provide frictional resistance thereto, and a back plate 12 fixed to the back surface of the friction material 11. The friction material 11 is made of asbestos hardened with a synthetic resin, and the coefficient of friction with the disc rotor 5 is adjusted to a desired value by adding anti-friction materials, friction-enhancing materials, etc. The back plate is made by punching a steel plate into the shape shown in FIG. , is movable in a direction parallel to the axis of the disc rotor 5. Friction material 11
As is clear from FIG. 2, the center of gravity of the friction surface that contacts the disc rotor 5 has a shape that almost coincides with the center line O of the piston 2, and the back plate 12 has an edge that slightly protrudes from the friction material 11. The shape and dimensions are determined so that In the outer part of the back plate 12, that is, in the part outside the circular arc C centered on the axis of the disk rotor 5 and passing through the center O of the piston 2, four through holes 14 are provided at approximately equal intervals along the circular arc C. It is formed. The ends of these through holes 14 on the disk rotor axis side are all located outside the circular arc C, and the ends of these through holes 14 on the disk rotor outer peripheral side are connected to the center O of the piston 2 and the friction material 1.
It is formed so as to pass through the center point of the line segment connecting the outer circumference side end of the disc rotor 1 and to be located outside the arc concentric with the arc C. The friction material 11 is fixed to the back plate 12 by molding,
During this molding, the material of the friction material 11 is
As shown in the figure, it flows into the through hole 14 and hardens, contributing to increasing the adhesion force between the friction material 11 and the back plate 12. In addition, as the material of the friction material 11 flows into the through hole 14, the compression ratio of the friction material material around the through hole 14, that is, the outside portion of the outer pad 6, during molding is reduced. It is presumed that the area is lower than the area shown in Figure 3, and is in a state where it is easily compressed and deformed. Inner pad 7
is exactly the same as outer pad 6.

In the disc brake configured as described above, when hydraulic pressure is applied to the cylinder part 3 from a port (not shown), the piston 2 presses the inner pad 7 against one surface of the disc rotor 5, and the reaction force causes the caliper 1 to move to the first position. Moving to the right in the figure, the reaction section 4 presses the outer pad 6 against the other surface of the disc rotor 5. In this case, if the disc rotor 5 is rotating at a high speed, it is necessary to apply high oil pressure to the cylinder section 3 to suppress its rotation, and as a result, the reaction section 4 is rotated as shown by the two-dot chain line in FIG. The tip side (disc rotor axis side) is deformed so as to widen. Of course, the caliper 1 deforms so that the working surface 15 of the piston 2 and the working surface 16 of the reaction part 4 are pushed apart, but the cylinder part 3 is moved parallel to the axis of the disc rotor 5 by a slide pin (not shown). Therefore, the inclination of the cylinder part 3 itself is relatively small, and most of the elastic deformation of the caliper 1 appears as the inclination of the reaction part 4.

If the reaction portion 4 is tilted in this manner, the pressing force on the outer pad 6 tends to be concentrated near the outer end 17 of the outer pad 6. Since the binding force of the back plate 12 on the friction material 11 is weakened at the outer part, the outer part of the friction material 11 is compressed relatively easily, and the back plate 12 is pressed against the working surface 16 of the reaction section 4. As a result, the inner portion of the friction material 11 is also sufficiently pressed against the disc rotor 5. In other words, since the friction material 11 is substantially thicker in the portion where the through hole 14 is provided, the force required to compress it by the same amount is smaller than in the portion without the through hole 14. I will be working on it. If the portion where the through hole 14 is provided is likely to be compressively deformed, the portion in the vicinity thereof is likely to swell toward the portion where the through hole 14 is provided, and as a result, the nearby portion is also likely to be compressively deformed. In addition, as mentioned above, the through hole 14 and its vicinity have a low compression rate during molding, so they are relatively easily compressed, which is also one of the reasons why the outer part of the outer pad is easily compressed. It is estimated that it has become popular. That is, the compression elastic modulus of the portion of the friction material 11 located outside the arc C is smaller than that of the portion located inside the arc C. Furthermore, by forming the through holes 14, the back plate 12
It is also conceivable that the bending stiffness of the outer part of the frame is moderately reduced, which helps to alleviate the local increase in surface pressure.

Whether or not the above considerations and estimations are valid is a subject for future research, but by forming the through holes 14, the contact of the outer pad 6 with the disc rotor 5 is improved, and the effectiveness during high-speed braking is improved. This improvement has been confirmed through experiments.

An example is shown below.

FIG. 4 is a diagram showing the results of a comparison between the contact situation of the pad according to the present invention shown in FIG. 2 with respect to the disk rotor 5 and the contact situation of the conventional pad shown in FIG. The pad 21 in Fig. 5 is the through hole 22.
The outer pad 6 is the same as the outer pad 6 shown in FIG. 2, except that it is provided almost uniformly over the entire surface of the back plate 23. In Fig. 4, the area A with wide hatching is the contact surface of the conventional pad 21 after the high-speed braking test, and the area B with narrow hatching is the contact surface of the outer pad 6 shown in Fig. 2. It's a hit.

Further, FIG. 6 is a graph showing the results of examining the relationship between the magnitude of the oil pressure applied to the cylinder portion 3 and the amount of displacement at point P in FIG. In FIG. 6, a positive displacement amount indicates that the point P approaches the disk rotor 5, and a negative displacement amount indicates that the point P moves away. The solid line in the figure represents the measurement results of the conventional pad 21. The displacement amount at point P initially increases slightly as the oil pressure increases, but it soon decreases and remains a positive value in the normal braking range U. However, it becomes a negative value in the latter half of the high-speed braking range H, indicating that the friction surface becomes separated from the disk rotor surface. On the other hand, the broken line indicates the amount of displacement at point P of the outer pad 6 according to the present invention, which hardly decreases in the regular braking range U, and decreases slowly even in the high-speed braking range H, so that the full-high-speed braking This shows that the value remains positive in region H, that is, the friction surface does not separate from the disc rotor.

Based on the above, according to the present invention, the outer pad 6
Although it has become clear that the non-uniformity of the contact surface pressure between the rotor and the disc rotor 5 is significantly alleviated, FIG. 7 shows the results of an investigation to see how much this improves the effectiveness during high-speed braking. This shows the results of a dynamo test that measures the amount of oil pressure required to decelerate the disk rotor 5, which is rotating at high speed, at a predetermined constant deceleration rate. The solid line in the figure shows the experimental results using the conventional pad 21, and the three points corresponding to each braking are the initial stage of braking,
Showing middle and late oil pressure. As is clear from the figure, when high-speed braking is performed twice in succession, the hydraulic pressure required to obtain the desired deceleration increases rapidly during the second braking, and a fade phenomenon occurs in the conventional pad 21. It is clear that On the other hand, for the pads 6 and 7 according to the present invention shown by broken lines, the oil pressure does not increase so much, and it can be seen that the occurrence of the fade phenomenon is prevented.

In addition, in this embodiment, not only the outer pad 6 but also the inner pad 7 were used in which through holes were formed only in the outer part, so that the inner pad and the outer pad could be used in common, and local fading could be avoided. This resulted in the effect of more effectively preventing the occurrence of the phenomenon. That is, as mentioned above, the cylinder part 3 side has less inclination than the reaction part 4 side, but the cylinder part 3 side has less inclination than the reaction part 4 side.
Some inclination may also occur on the sides, so if the same material as the outer pad 6 is used for the inner pad 7, the non-uniformity of the contact surface pressure of the inner pad 7 will be alleviated for the same reason. Furthermore, if the working surface 15 of the piston 2 is allowed to tilt closer to the disk rotor 5 on the outside than on the inside, the inclination of the working surface 16 of the reaction part 4 will be reduced by that much. From this point of view as well, it is effective in preventing the occurrence of local fading.

Furthermore, in disc brakes in which the cylinder part is not supported by a slide pin, but the connecting part connecting the cylinder part and the reaction part is slidably supported by a support member, the cylinder part Since a relatively large inclination also occurs in the inner pad, it is particularly effective to apply the present invention to the inner pad as well.

However, since the effects of the present invention are particularly noticeable on the reaction side, that is, on the outer pad side, the effects of the present invention can be fully enjoyed even if the present invention is applied only to the outer pad.

Since the present invention is as detailed above,
By making only a slight change to the shape of the pad's back plate, without complicating the structure or increasing manufacturing costs, we can overcome the serious drawback of floating caliper type disc brakes, which is the reduced effectiveness at high speed braking. It has an excellent effect of significantly relieving the symptoms.

[Brief explanation of the drawing]

Fig. 1 is a front cross-sectional view of a disc brake that is an embodiment of the present invention, Fig. 2 is a rear view of an outer pad used in the disc brake shown in Fig. 1, and Fig. 3 is a - cross-section in Fig. 2. It is a diagram. FIG. 4 is an explanatory diagram showing how the contact of the outer pad of FIG. 2 with respect to the disc rotor is improved. FIG. 5 is a rear view of an example of a conventional pad. Figure 6 shows the relationship between the displacement amount of the point P on the disk rotor axis side of the pad according to the present invention shown in Figure 2 and the oil pressure applied to the cylinder section, compared to the conventional pad shown in Figure 5. It is a graph shown in comparison. FIG. 7 is a graph showing the effectiveness of the pad according to the present invention shown in FIG. 2 during high-speed braking in comparison with the conventional pad shown in FIG. 5. DESCRIPTION OF SYMBOLS 1... Caliper, 2... Piston, 3... Cylinder part, 4... Reaction part, 5... Disc rotor, 6... Outer pad, 7... Inner pad, 8... Supporting member, 11... Friction material, 12...
Back plate, 14...through hole, O...piston center line,
C...A circular arc centered on the disk rotor axis and passing through the piston center line.

Claims (1)

[Claims for Utility Model Registration] (1) A piston is provided with a cylinder part into which a piston is fitted and a reaction part formed opposite to the cylinder part, and is moved in a direction parallel to the axis of the disc rotor by means of a support member. A pad that is pressed against the disc rotor by a floating caliper that is movably supported to suppress rotation of the disc rotor, a friction material that contacts the disc rotor to provide frictional resistance, and a back side of the friction material. and a back plate fixed to the back plate, wherein the back plate has a plurality of through holes, the ends of the through holes on the disk rotor axis side are centered on the disk rotor axis, and the piston center line is located outside the circular arc passing through, and with the ends of the through holes on the outer circumferential side of the disk rotor concentric with the circular arc, and in the center of the line segment connecting the center line of the piston and the end of the friction material on the outer circumferential side of the disk rotor; The disk rotor is formed so as to be located on the outside of the circular arc passing through the point, while the through hole is not formed inside the circular arc passing through the center line of the piston. A pad for a disc brake, characterized in that the elastic coefficient of compression of the friction material in a portion outside the circular arc passing through the center line is smaller than the elastic modulus of the compression material in the portion inside the circular arc. (2) When the friction material is molded onto the back plate, the material of the friction material flows into the through hole and hardens, thereby increasing the adhesion force between the friction material and the back plate. A pad for a disc brake according to claim 1 of the registered utility model.