JP2009174610A - Disc brake - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain noise in braking, to improve an operation feeling, and to reduce dragging torque in non-braking, in a multi-pot type disc brake for pressing one pad by a plurality of pistons, as a target. <P>SOLUTION: This disc brake is provided for slidingly contacting the one pad with a disc rotor by pressing the pad by the plurality of pistons. A shim 6 of removing the most closely adjacent to an adjacent pressing object part in a symmetrical shape by a cutout part 8 with the line CL of dividing mutual pressing object parts into two equal parts among the ring-shaped pressing object part 7 contacting with the tip of the respective pistons, is provided between the pistons and the pad. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a disc brake for a vehicle that suppresses uneven wear of friction pads to improve operational feeling during braking, suppress noise (brake noise), reduce drag torque during non-braking, and the like.

  As a conventional example of a disc brake, for example, there is one described in Patent Document 1 below. In the disc brake disclosed in the same document, a plurality of cylinders are provided in the caliper, and a single friction pad (hereinafter simply referred to as a pad) is pressed by a plurality of pistons inserted in the respective cylinders to the disc rotor. This is a so-called multi-pot type disc brake that is in sliding contact.

  By the way, in the disc brake, various measures are taken in order to reduce the noise at the time of braking and the drag torque at the time of non-braking which causes deterioration of fuel consumption. For example, in the above-mentioned Patent Document 1, a notch shim is interposed between a pad and a piston that presses the pad shim so that the pad surface pressure (the pressure at which the friction surface of the pad is pressed against the disk rotor) on the rotation side of the disk rotor. ) And the pad surface pressure on the inner and outer diameter sides of the disc rotor is reduced to suppress brake noise.

Moreover, there exists a technique which the following patent document 2 is disclosed regarding reduction of the drag torque. The technique disclosed in Patent Document 2 is intended for a floating type disc brake, and a caliper supported so as to be slidable in the disc axial direction can be tilted following the disc rotor when braking. Thus, uneven wear of the pad is suppressed, and when the brake is not applied, the inclination of the caliper is suppressed to prevent an increase in drag torque.
JP 2000-220669 A Japanese Patent Laid-Open No. 08-145088

  A multi-pot type disc brake may generate noise during braking even if the countermeasures disclosed in Patent Document 1 are taken. Further, even when a notch shim as disclosed in Patent Document 1 is used, the feeling of operation during braking may be deteriorated, and drag torque during non-braking may be promoted.

  These problems are likely to occur in a multi-pot type disc brake in which adjacent pistons are arranged close to each other. The inventors considered that a plurality of pistons being too close to each other caused the problem. There are many causes of drag and brake squeal, and the methods disclosed in Patent Documents 1 and 2 are expected to be effective for brake squeal and drag when multiple pistons are too close to each other. Can not. Therefore, a new countermeasure was sought, and a structure that can cope with the above-described problems without changing the distance between the centers of the pistons was found.

  An object of the present invention is to employ such a structure to suppress noise during braking, improve operational feeling, and reduce drag torque during non-braking in a multi-pot type disc brake.

In order to solve the above-described problems, in the present invention, a pressure relief part that makes it difficult to transmit the pressing force is provided in a part of the ring-shaped pressed part that is pressed by the piston, and the pad surface pressure in the central part of the piston is set. Reduced.
Specifically, in a disc brake in which one pad is pressed by a plurality of pistons and slidably contacted with a disc rotor, the adjacent pressed portions are closest to each other among the ring-shaped pressed portions that contact the tip of each piston. The shim was removed between the piston and the pad so that the part to be removed was removed symmetrically about the line that bisects the pressed part.

  As another structure, in the disc brake under the same preconditions, a mold hole is provided as a pad in which a part of the friction material enters the pad back plate, and the mold hole receives a pressing force from the tip of each piston. The pad formed in the site | part which the adjacent pressed part adjoins among the ring-shaped pressed parts was provided.

  In the former disc brake, a portion from which a part of the shim is removed functions as a pressure release portion, and in the latter disc brake, a mold hole installation portion of the pad back plate serves as a pressure release portion.

  The former disc brake can also remove the designated part of the shim in a lump, but the removal is made by providing a cutout part in the shim and independently for each pressed part. It is preferable.

  Further, the independent cut-out portion has two edges along a radial line passing through the center of the pressed portion, and of the two peripheral edges, the peripheral edge far from the center of the pressed portion is the covered portion. What formed the shape which makes the circular arc concentric with the center of a press part is more preferable.

  The disc brake according to the present invention is a mold provided on a shim removal portion or a pad back plate that serves as a pressure release portion in a portion where the adjacent pressed portions are closest to each other among the ring-shaped pressed portions with which the tip ends of the pistons are in contact. Since the hole is arranged, it is possible to prevent the pressure by the piston at the portion where the pressed portion is closest to the portion from being excessively excessive as compared with other portions. For this reason, variations in the pad surface pressure at each part of the friction surface are reduced, and uneven wear of the friction material is suppressed, resulting in the effects of suppressing noise during braking, improving operational feeling, and reducing drag torque during non-braking. It comes to be.

When the distance between the centers of adjacent pistons is short, the friction material of the pad wears larger at the center in the same direction than both ends of the piston, and the friction surface deforms into a concave shape (the pad bends due to the pressing force). This phenomenon is caused by an increase in the brake pedal stroke due to the uneven wear, which further deteriorates the feeling of operation, and further causes noise during braking and dragging during non-braking.
Even if the distance between the centers of adjacent pistons is short, the disc brake of the present invention can average the surface pressure distribution of the pad without changing the distance, thereby solving the problem by suppressing uneven wear. Can do.

  In addition, in the disc brake in which the specified portion of the shim is removed independently for each of the pressed parts, the shim connecting portion is secured between the adjacent cutout portions, so the strength of the shim is reduced due to the installation of the cutout portion. Is small, and the durability of the shim is suppressed. The edge of the independent cutout part is along a radial line passing through the center of the pressed part, and the peripheral edge far from the center of the pressed part among the two peripheral edges forms a concentric arc with the center of the pressed part. The shim can remove a necessary part without unnecessarily increasing the area of the cutout portion, and the effect of maintaining the strength of the shim is particularly great.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a piston-opposed disc brake to which the present invention is applied. In this disc brake, a plurality of cylinders 2 are formed on the inner part 1a and the outer part 1b of the caliper 1, respectively, and a pair of pads (frictions) are arranged opposite to each other with a piston 3 inserted into the cylinder 2 with a disk rotor 5 in between. Press the pad 4 individually. The pad 4 is configured by combining a friction material 4a and a pad back plate 4b, and in the illustrated piston-facing disc brake, a pad pin 10 that is horizontally mounted between the inner portion 1a and the outer portion 1b of the caliper 1 is padded. It is slidably supported in the disk axial direction through a pin hole (not shown) provided in the back plate 4b.

  In the illustrated disc brake, the caliper 1 is fixed at a fixed position, and one pad 4 is pressed by two pistons 3 on both the inner side and the outer side, and is in sliding contact with the disc rotor 5. A shim 6 is interposed between the piston 3 and the pad 4, and the shim 6 is provided with the characteristics shown in FIGS.

  2 to 4 show the shim 6 in a simplified manner. The figure does not include the claw for locking the pad. 2 to 4 in FIG. 2 is a shim pressed portion where the tips of two adjacent pistons 3 and 3 are in contact with each other. The piston 3 is a hollow cup-shaped piston, and therefore the pressed portion 7 has a ring shape. The pressed parts 7 are arranged in a horizontal row corresponding to the two pistons 3 and 3 provided side by side, and among the ring-shaped pressed parts, the adjacent pressed parts 7 and 7 are closest to each other. However, it is removed symmetrically about a line CL that bisects between the pressed parts 7 and 7. The removal is realized by providing a cutout 8 in the shim 6.

  The shim 6 in FIG. 2 is obtained by removing the designated portions of the adjacent pressed portions 7 and 7 collectively by one cutout portion 8, and there is no shim connecting portion between the removed portions. On the other hand, in the shim 6 of FIGS. 3 and 4, the cutout portion 8 is individually provided for the adjacent pressed portions 7 and 7, and the designated portion is removed independently.

  The cutout portion 8 provided in the shim 6 in FIG. 3 is square, but the cutout portion 8 provided in the shim 6 in FIG. 4 is a part of the shim connecting portion 6a left between the adjacent cutout portions 8 and 8. A large width w can be secured, and the effect of maintaining the strength and improving the durability of the shim 6 is excellent. The cutout portion 8 provided in the shim 6 in FIG. 4 has two end edges 8a, 8a along a radial line RL passing through the center (piston center) O of the pressed portion 7 and the covered edge of the two peripheral edges. The peripheral edge 8b on the side far from the center of the pressing part 7 has a fan shape that is a concentric arc with the center O of the pressed part 7, and the width w of the connecting part 6a increases toward both ends of the cutout part 8. .

  In addition, since the appropriate removal range changes with specifications of a brake for the removal of a part of the to-be-pressed part 7, it calculates | requires the range which can suppress the difference of the pad surface pressure in each part of a friction surface, and removes that part.

  FIG. 5 shows an example in which the pad 4 is provided with a pressure releasing portion that makes it difficult to transmit the pressing force in a part of the pressed portion 7. The pad 4 is provided with a mold hole 9 penetrating the pad back plate 4b, and a part of the friction material 4a is inserted into the mold hole 9. By doing so, the shear resistance is increased. . The mold hole 9 is provided in an inner region of the pressed portion 7 in a general pad.

On the other hand, the pad 4 in FIG. 5 is provided with a mold hole 9 in a portion where the adjacent pressed portions 7 and 7 are closest to each other among the ring-shaped pressed portions pressed by the piston of the pad back plate 4b. In the portion where the mold hole 9 is provided, the pressing force by the piston is applied to the friction material 4a having extremely low rigidity compared to the pad back plate 4b. As a result, the pressing force is weakened at the center of the pad provided with the mold hole 9, the pad surface pressure at the center is reduced, and the variation in the surface pressure distribution is reduced.
When the pad 4 shown in FIG. 5 is used in, for example, the disc brake shown in FIG. 1, the same effect as that of a disc brake having a shim having a pressure relief portion can be obtained without shims, and the economic effect is enhanced.

  Although the above description has been given by taking a piston-facing disc brake as an example, the subject of application of the present invention includes a floating disc brake as shown in the above-mentioned Patent Document 1.

The top view which shows embodiment of the disc brake of this invention The front view which shows the 1st form of the shim employ | adopted as the disc brake of FIG. The front view which shows the 2nd form of the shim employ | adopted as the disc brake of FIG. The front view which shows the 3rd form of the shim employ | adopted as the disc brake of FIG. (A) The rear view which shows one form of the pad employ | adopted as the disc brake of this invention, (b) Sectional drawing of a pad same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Caliper 1a Inner part 1b Outer part 2 Cylinder 3 Piston 4 Pad 4a Friction material 4b Pad back plate 5 Disc rotor 6 Shim 6a Joint part 7 Pressed part 8 Cutout part 8a Edge 8b Perimeter 9 Mold hole 10 Pad pin

Claims (4)

  In a disc brake in which one friction pad (4) is pressed by a plurality of pistons (3) to be brought into sliding contact with the disc rotor (5), a ring-shaped pressed portion (7) in which the tip of each piston (3) is in contact Among these, the shim (6) in which the portion where the adjacent pressed portions (7, 7) are closest to each other is removed symmetrically about the line (CL) that bisects the adjacent pressed portions. A disc brake provided between the piston (3) and the friction pad (4).   Each of the pressed parts (7) corresponding to each piston (3) is removed by providing the shim (6) with a cutout part (8). The disc brake according to claim 1, wherein the disc brake is made independently.   The cut-out portion (8) has two edge portions (8a) along a radial line (RL) passing through the center (O) of the pressed portion (7), and the pressed portion of two peripheral edges. 3. The disc brake according to claim 2, wherein the peripheral edge (8b) on the side far from the center (O) of the portion forms a circular arc concentric with the center (O) of the pressed portion. In the disc brake in which one friction pad (4) is pressed by a plurality of pistons (3) to be brought into sliding contact with the disc rotor (5), the friction pad (4) is:
The pad back plate (4b) is provided with a mold hole (9) into which a part of the friction material (4a) enters, and the mold hole (9) is a ring-shaped substrate that receives a pressing force from the tip of each piston (3). A disc brake comprising a friction pad (4) formed at a position where two adjacent pistons (3, 3) are closest to each other in the pressing portion (7).

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