Piston of disc brake, and disc brake

Abstract

To provide a piston of a disc brake that can improve stability in pressing against a brake pad while maintaining a brake feeling with a feeling of rigidity, and the disc brake.SOLUTION: A first piston 5 (a piston of the present invention) comprises a brake pad opposite surface part 5a, having an external diameter larger than the internal diameter of a cylinder hole 3c, integrally on the opposite surface side opposed to a brake pad 4. The brake pad opposite surface part 5a has an external diameter large enough to abut on an outer shape end of the brake pad 4. The brake pad opposite surface part 5a comprises a groove 5c concentric with the first piston 5. The disk brake 1 has the first piston 5 inserted into a cylinder hole 3c provided on the most disk rotating-in side and a cylinder hole 3c provided on the most disk rotating-out side in vehicle forward traveling.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a piston for a disc brake and a disc brake. [Background technology]

[0002] Conventionally, disc brakes have a piston inserted into a cylinder hole formed in a caliper body, and the piston presses the brake pads to abut against the disc rotor. In order to improve the stability of the pressure on the brake pads, some pistons have a piston cap attached to the surface facing the brake pads, the piston cap having an outer diameter larger than the inner diameter of the cylinder hole (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-141534 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned Patent Document 1, the piston cap is attached to the piston by inserting multiple claws into the piston and engaging with the inner peripheral surface of the piston. This makes it easy for rattle to occur between the piston and the piston cap, and the piston cap may come into contact with the brake pad in an inclined state, which may result in a brake feeling with a loss of rigidity.

[0005] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a disc brake piston and a disc brake that can improve the stability of the pressure applied to the brake pads while maintaining a braking feeling with a sense of rigidity. [Means for solving the problem]

[0006] In order to achieve the above object, the piston of the disc brake of the present invention is characterized in that it is integrally provided with a brake pad opposing surface portion on the opposing surface side facing the brake pad, the brake pad opposing surface portion having an outer diameter larger than the inner diameter of the cylinder hole.

[0007] Furthermore, the disc brake of the present invention is characterized in that, in a disc brake having an operating portion with a plurality of cylinder holes on at least one side of the disc rotor, a piston having an integral brake pad opposing surface portion is inserted into the cylinder hole provided on the most inward disc rotation side and the cylinder hole provided on the most outward disc rotation side of the operating portion when the vehicle moves forward. Effect of the Invention

[0008] According to the disc brake piston and disc brake of the present invention, the piston is integrally provided with a brake pad-facing surface portion having an outer diameter larger than the inner diameter of the cylinder bore, thereby improving the stability of pressure on the brake pad while maintaining a braking feeling with a sense of rigidity. [Brief description of the drawings]

[0009] [Figure 1] 1 is a front view showing an example of a disk brake according to the present invention; [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II of FIG. [Diagram 3] FIG. 1 is a perspective view showing an example of a piston of the present invention. [Figure 4] FIG. [Diagram 5] FIG. 5 is a cross-sectional view of FIG. 4 . [Figure 6] FIG. 4 is a schematic diagram showing the position of a piston contacting a brake pad. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 1 and 2 are diagrams showing an example of a disk brake according to the present invention. Note that arrow A indicates the rotation direction of a disk rotor that rotates together with the wheel when the vehicle moves forward, and the disk rotation outward and inward sides described below are those when the vehicle moves forward.

[0011] The disc brake 1 of this embodiment comprises a disc rotor 2 that rotates integrally with the wheel, a caliper body 3 that is attached to the vehicle body on one side of the disc rotor 2, and brake pads 4, 4 that are arranged facing each other across the disc rotor 2 between acting portions 3a, 3a of the caliper body 3 that are disposed on both sides of the disc rotor 2.

[0012] The caliper body 3 is formed as a six-pot piston opposed type, with a pair of action parts 3a, 3a connected by a bridge part 3b that straddles the outer periphery of the disc rotor 2. Three cylinder holes 3c are formed in each of the action parts 3a, 3a, facing each other. A first piston 5 is inserted into the cylinder hole 3c on the disc rotation out side and the cylinder hole 3c on the disc rotation in side, and a second piston 6 is inserted into the central cylinder hole 3c.

[0013] The second piston 6 is a conventional piston formed in a cylindrical shape with a bottom, and is inserted into the cylinder hole 3c with its opening facing the disk rotor 2 side.

[0014] The first piston 5 is an example of the piston of the present invention. The first piston 5 is formed in a cylindrical shape with a bottom, and is inserted into the cylinder hole 3c with the opening facing the disc rotor 2. Furthermore, the first piston 5 is integrally provided with a brim-shaped brake pad facing surface portion 5a having an outer diameter larger than the inner diameter of the cylinder hole 3c on the facing surface side (opening side) facing the brake pad 4. Also, as shown in FIG. 6, the brake pad facing surface portion 5a has an outer diameter that protrudes outward in the disc radial direction from the outer edge 4a on the outer side of the disc radial direction of the brake pad 4 and inward in the disc radial direction from the outer edge 4b ​​on the inner side of the disc radial direction, and during braking, the brake pad facing surface portion 5a abuts against the outer edge 4a on the outer side of the disc radial direction of the brake pad 4 and the outer edge 4b ​​on the inner side of the disc radial direction, respectively. Furthermore, the brake pad facing surface portion 5a is provided with an annular groove 5c concentric with the first piston 5 on the facing surface 5b facing the brake pad 4.

[0015] Next, the surface pressure distribution applied to the brake pad 4 during braking in the disc brake 1 of this embodiment was analyzed and compared with the surface pressure distribution applied to the brake pad 4 during braking in a conventional disc brake in which the second piston 6 is inserted into all of the cylinder holes 3c. As a result, in the conventional disc brake, the surface pressure in region B (FIG. 6) on the disc rotation side of the brake pad and on the outer radial side of the disc was particularly high compared to other regions. On the other hand, in this embodiment, the surface pressure in region B could be particularly reduced, and the surface pressure applied to the brake pad 4 during braking could be made approximately uniform.

[0016] As described above, since the first piston 5 is integrally provided with the brake pad facing surface portion 5a, it is possible to improve the stability of the pressure on the brake pad 4 while maintaining a braking feeling with a sense of rigidity. This also makes it possible to increase the braking effect and prevent uneven wear of the brake pad 4. In addition, by providing the annular groove 5c concentrically with the first piston 5 on the facing surface 5b of the brake pad facing surface portion 5a, it is possible to suppress the transmission of braking heat to the first piston 5 via the brake pad 4.

[0017] Furthermore, by inserting the first piston 5 into the cylinder hole 3c on the disc rotation side and the cylinder hole 3c on the disc rotation side, the above-mentioned disc brake 1 is able to control the surface pressure on the disc rotation side and the disc rotation side, thereby controlling the servo effect and braking force.

[0018] The disc brake of the present invention is not limited to the above-mentioned embodiment, and the brake pad facing surface portion may have an outer diameter that overlaps with the outer end position of the brake pad on the radially outer side of the disc and the outer end position of the brake pad on the radially inner side of the disc, and the brake pad facing surface portion 5a may abut against the outer end 4a of the brake pad 4 on the radially outer side of the disc and the outer end 4b of the brake pad 4 on the radially inner side of the disc, respectively, during braking. The present invention can be applied to any type of disc brake, and the number of pistons is also arbitrary. Furthermore, in a disc brake having two or more pistons, the piston of the present invention may be used for all the pistons, or the piston of the present invention may be inserted into any part of the cylinder holes. [Explanation of symbols]

[0019] 1... disc brake, 2... disc rotor, 3... caliper body, 3a... action portion, 3b... bridge portion, 3c... cylinder hole, 4... brake pad, 4a, 4b... outer end portion, 5... first piston (piston of the present invention), 5a... brake pad facing surface portion, 5b... facing surface, 5c... groove, 6... second piston

Claims

1. In a piston of a disc brake, which is inserted into a cylinder hole formed in a caliper body and presses a brake pad against a disc rotor, 13. A piston for a disc brake, comprising: a piston body having a brake pad facing surface portion integrally formed on a facing surface side facing the brake pad, the brake pad facing surface portion having an outer diameter larger than an inner diameter of the cylinder hole.

2. 2. The piston for a disc brake according to claim 1, wherein the brake pad facing surface has an outer diameter capable of abutting against an outer edge of the brake pad.

3. 2. The piston of a disc brake according to claim 1, wherein the brake pad facing surface portion is provided with an annular groove concentric with the piston.

4. A disk brake having an action portion having a plurality of cylinder holes on at least one side of a disk rotor, 4. A disc brake, characterized in that the piston according to claim 1 is inserted into a cylinder hole provided on the most inward disc rotation side of the acting portion when the vehicle is moving forward, and a cylinder hole provided on the most outward disc rotation side of the acting portion.

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