Disc brake

Abstract

To provide a disc brake capable of reliably suppressing uneven wear of a brake pad.SOLUTION: An acting part 3a of a caliper body 3 disposed on both sides of a disc rotor 2 is provided with turn-in side pistons 6 provided on a turn-in side at the time when a vehicle moves forward, and turn-out side pistons 5 provided on a turn-out side, and the turn-in side piston 6 and the turn-out side piston 5 are connected with a connection member 7. The turn-in side piston 6 is provided with a female screw hole 6c (fixing portion) to which a fixing piece 7b provided at one end of the connection member 7 is fixed, and the turn-out side piston 5 is provided with an engagement portion 5c with which an engagement piece 7c provided at the other end of the connection member 7 is engaged. The engagement portion 5c is formed such that, during non-braking, the turn-out side piston 5 is protruded to a brake pad 4 side more than the turn-in side piston 6 by contact with the engagement piece 7c.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a disc brake, and more particularly to a disc brake that is designed to suppress uneven wear of a brake pad. [Background technology]

[0002] Conventionally, in disc brakes equipped with two pistons arranged side by side in the circumferential direction of the disc in a caliper body, a shim plate is used to connect the two pistons in order to suppress uneven wear of the brake pads, so that the two pistons press evenly against the brake pads when braking (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-270692 Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, in a disc brake, the disc rotation side of the brake pad is caught in the rotation of the disc rotor due to the servo effect during braking, so that the disc rotation side of the brake pad wears more than the disc rotation side. In the above-mentioned Patent Document 1, although the two pistons can press the brake pad evenly, it is not possible to suppress uneven wear of the brake pad caused by the servo effect.

[0005] In particular, if the brake pads become warped due to temperature changes or the brake pads are repeatedly used, uneven wear of the brake pads may become noticeable, and there is a risk that the braking effect will not be stable.

[0006] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a disc brake that suppresses uneven wear of the brake pads and can provide stable braking effect from the time of a new product until it reaches its limit of use. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the disc brake of the present invention is characterized in that the operating portion of the caliper body, which is arranged on at least one side of a pair of brake pads provided on both sides of a disc rotor, has a rotation-in side piston provided on the rotation-in side of the disc rotor when the vehicle is moving forward, and a rotation-out side piston provided on the rotation-out side, and in that the brake pads are pressed against the disc rotor by the rotation-in side piston and the rotation-out side piston, the rotation-in side piston has a connecting member that connects to the rotation-out side piston, and the connecting member connects the rotation-out side piston so that the rotation-out side piston protrudes toward the brake pad side more than the rotation-in side piston. Effect of the Invention

[0008] According to the disc brake of the present invention, uneven wear of the brake pads is suppressed, and a stable braking effect can be exhibited from the time of a new product until it reaches its limit of use. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a cross-sectional view of FIG. [Diagram 2] 1 is a front view of a disk brake showing one embodiment of the present invention; [Diagram 3] FIG. 4 is an enlarged explanatory view of a main portion of the disc brake when not in braking mode. [Figure 4] FIG. 2 is an explanatory diagram of a main portion of the disc brake when not in braking mode. [Diagram 5] 11 is an explanatory diagram showing the function of a connecting member during braking. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 1 to 5 are diagrams showing an example of a disk brake according to the present invention. Arrow R indicates the rotation direction of the 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 comprises a disc rotor 2 that rotates integrally with the wheel, a piston-opposed caliper body 3 that is attached to the vehicle body on one side of the disc rotor 2, a pair of brake pads 4, 4 arranged on both sides of the disc rotor 2, a rotation side piston 5 and a rotation side piston 6 that press the brake pads 4, 4 against the disc rotor 2, and a connecting member 7 that connects the rotation side piston 5 and the rotation side piston 6.

[0012] The caliper body 3 includes a pair of action parts 3a, 3a, and a bridge part 3b that connects the pair of action parts 3a, 3a across the disc rotor 2. A large-diameter cylinder hole 3c that opens on the disc rotor 2 side is provided on the disc rotation side of each action part 3a, and a small-diameter cylinder hole 3d that opens on the disc rotor 2 side is provided on the disc rotation side. In addition, bolt insertion holes 3e, 3e are formed in the disc radial direction on the disc rotation side and the disc rotation side of one action part 3a, and the caliper body 3 is attached to the vehicle body by screwing mounting bolts (not shown) inserted into the bolt insertion holes 3e, 3e into the caliper mounting parts provided on the vehicle body side.

[0013] The rotation-side piston 5 is formed with a larger diameter than the rotation-side piston 6, has a bottomed cylindrical shape with a bottom wall 5a and a peripheral wall 5b, and is inserted into the rotation-side cylinder hole 3c with the opening side facing the brake pad side. An engagement portion 5c for engaging the connecting member 7 is provided on the opening side of the peripheral wall 5b, protruding from the peripheral wall 5b toward the inside of the piston and the bottom wall 5a side. Furthermore, a notch portion 5d for locating the connecting piece 7a of the connecting member 7 is formed on the opening side of the peripheral wall 5b and on the disk rotation side.

[0014] The engaging portion 5c has a brake pad side surface formed flush with the brake pad side surface of the peripheral wall 5b, and together with the brake pad side surface of the peripheral wall 5b, forms a rotation-side abutment surface 5f that abuts against the brake pad 4 during braking.

[0015] The rotation-in piston 6 is formed with a smaller diameter than the rotation-out piston 5, and like the rotation-out piston 5, is a bottomed cylinder having a bottom wall 6a and a peripheral wall 6b, and is inserted into the rotation-in cylinder hole 3d with the opening side facing the brake pad side. The bottom wall 6a is formed with a thick wall, and a female screw hole 6c (fixing part of the present invention) for attaching the connecting member 7 is formed in the center of the inner surface. Furthermore, a notch 6d is formed on the opening side of the peripheral wall 6b on the disc rotation side, in which the connecting piece 7a of the connecting member 7 is disposed.

[0016] In addition, hydraulic pressure chambers 3f, 3f are formed between the rotation-outlet side cylinder hole 3c and the rotation-outlet side piston 5, and between the rotation-inlet side cylinder hole 3d and the rotation-inlet side piston 6, and each hydraulic pressure chamber 3f is connected by a hydraulic passage 8.

[0017] Each brake pad 4 comprises a lining 4a which comes into sliding contact with the side surface of the disc rotor 2, and a metal backing plate 4b to which the lining 4a is attached.

[0018] The connecting member 7 is formed of an elastic plate-like member and has a circular fixing piece 7b at one end laid on the inner surface of the bottom wall 6a of the rotation-in side piston 6 and an engagement piece 7c at the other end that engages with the engagement part 5c of the rotation-out side piston 5, the fixing piece 7b and the engagement piece 7c being connected by a connecting piece 7a. The fixing piece 7b has a screw insertion hole 7d in the center, and the connecting member 7 is fixed to the rotation-in side piston 6 by screwing a male screw 9 inserted into the screw insertion hole 7d into the female screw hole 6c of the rotation-in side piston 6.

[0019] 3, the engagement piece 7c has an engagement surface 7e that abuts against the bottom wall side surface 5e of the engagement portion 5c, which is formed parallel to the brake pad 4. Also, a length dimension D2 from the engagement surface 7e to the brake pad side surface 7f of the connecting piece 7a is formed shorter than a length dimension D1 from the bottom wall side surface 5e of the engagement portion 5c to the rotation-side abutment surface 5f.

[0020] The connecting piece 7a is formed closer to the brake pad 4 than the fixed piece 7b and the engaging piece 7c, and is disposed parallel to the brake pad 4 via the cutouts 5d and 6d.

[0021] The connecting member 7 thus formed is attached across the rotation-in side piston 6 and the rotation-out side piston 5 by fixing the fixed piece 7b to the rotation-in side piston 6 with the male screw 9 and engaging the engagement piece 7c with the engagement part 5c. With this attachment, even when braking is not being applied, the elastic force of the connecting member 7 causes the engagement piece 7c to bias the engagement part 5c toward the brake pad 4, and the rotation-out side piston 5 is positioned so as to protrude toward the brake pad side more than the rotation-in side piston 6. That is, as shown in FIG. 4, when braking is not being applied, the distance D3 from the rotation-out side abutment surface 5f of the rotation-out side piston 5 to the disc rotor 2 is shorter than the distance D4 from the rotation-in side abutment surface 6e, where the rotation-in side piston 6 abuts against the brake pad 4 when braking, to the disc rotor 2, and the rotation-out side abutment surface 5f is located closer to the brake pad 4 than the rotation-in side abutment surface 6e.

[0022] When hydraulic pressure is supplied to the hydraulic pressure chambers 3f, 3f during braking as shown in Fig. 5, the rotation-side abutment surface 5f is located closer to the brake pad 4 than the rotation-side abutment surface 6e, and the rotation-side piston 6 is pressed by hydraulic pressure, so that the elastic force of the connecting member 7 causes the engagement piece 7c to further urge the engagement part 5c toward the brake pad 4 (arrow A), causing the rotation-side piston 5 to abut against the brake pad 4 and press the brake pad 4. At this time, a reaction force (arrow B) in the direction opposite to the brake pad is generated on the rotation-side of the disc that includes the fixed piece 7b of the connecting member 7. Therefore, after the rotation-side piston 5 abuts against the brake pad 4, the rotation-side piston 6 is pressed by hydraulic pressure that is a force (arrow C) greater than the reaction force (arrow B). Even at such hydraulic pressure, the engagement piece 7c further urges the engagement portion 5c toward the brake pad 4 (arrow A), so that the rotation-outlet side piston 5 is pressed against the brake pad 4 with a stronger force than the rotation-inlet side piston 6.

[0023] As described above, the surface pressure of the disc rotation side of the brake pad 4 is always higher than that of the disc rotation side from the beginning of braking. Furthermore, since the rotation side piston 5 has a larger diameter than the rotation side piston 6, a large surface pressure is applied to the rotation side of the brake pad 4. For this reason, the disc rotation side of the brake pad 4 wears, but when the rotation side piston 6 starts to press the brake pad 4, a servo effect causes a large surface pressure to be applied to the disc rotation side of the brake pad 4, causing the disc rotation side of the brake pad 4 to wear. This makes it possible to balance the wear of the disc rotation side and the disc rotation side of the brake pad 4, thereby suppressing uneven wear.

[0024] By forming the disc brake 1 of this embodiment as described above, uneven wear of the brake pad 4 can be reliably suppressed, and the brake pad 4 can exhibit stable braking effect from when it is new until it reaches its usage limit. Even if the brake pad 4 warps and the center becomes more convex toward the brake pad 4 side than the disc rotation side end and the disc rotation side end, the surface pressure on the disc rotation side is high, and the surface pressure on the disc rotation side is high due to the servo effect, so that the brake pad 4 can be pressed well and uneven wear can be suppressed.

[0025] In addition, the elasticity of the connecting member 7 can be changed as desired, and by changing the elasticity of the connecting member 7, it becomes possible to control the wear on the disc rotation side and the wear on the disc rotation side of the brake pad 4. Furthermore, the diameters of the rotation side piston 5 and the rotation side piston 6 can be changed as desired to control the wear of the brake pad 4.

[0026] The present invention is not limited to piston-opposed type disc brakes having acting portions on both sides of the disc rotor as in the above-described embodiment, but can also be applied to pin-slide type disc brakes having an acting portion on one side of the disc rotor. [Explanation of symbols]

[0027] 1...disc brake, 2...disc rotor, 3...caliper body, 3a...action portion, 3b...bridge portion, 3c...rotation-side cylinder hole, 3d...rotation-side cylinder hole, 3e...bolt insertion hole, 3f...hydraulic pressure chamber, 4...brake pad, 4a...lining, 4b...lining, 5...rotation-side piston, 5a...bottom wall, 5b...circumferential wall, 5c...engagement portion, 5d...notch portion, 5e...bottom wall side, 5f...rotation-side abutment surface, 6...rotation-side piston, 6a...bottom wall, 6b...circumferential wall, 6c...female thread hole, 6d...notch portion, 6e...rotation-side abutment surface, 7...connecting member, 7a...connecting piece, 7b...fixing piece, 7c...engagement piece, 7d...screw insertion hole, 7e...engagement surface, 7f...brake pad side, 8...fluid passage hole, 9...male thread

Claims

1. A disc brake including a caliper body having an action portion disposed on at least one side of a pair of brake pads provided on both sides of a disc rotor, the action portion including a rotation-in side piston provided on the rotation-in side of the disc rotor when the vehicle is moving forward, and a rotation-out side piston provided on the rotation-out side, the brake pads being pressed against the disc rotor by the rotation-in side piston and the rotation-out side piston, The inlet piston includes a connecting member that connects to the outlet piston, The disc brake is characterized in that the connecting member connects the rotation-side piston so that the rotation-side piston protrudes toward the brake pad side further than the rotation-side piston.

2. The inlet piston is provided with a fixing portion for fixing one end of the connecting member, and the outlet piston is provided with an engaging portion for engaging the other end of the connecting member, The disc brake according to claim 1, characterized in that the engaging portion is formed by the connecting member so that, when not braking, the rotation-side abutment surface where the rotation-side piston abuts against the brake pad when braking is located closer to the brake pad than the rotation-side abutment surface where the rotation-side piston abuts against the brake pad when braking.

3. The connecting member is elastic. When the rotation-side piston is pressed during braking, the rotation-side piston is biased toward the brake pad by the connecting member, 3. The disc brake according to claim 2, wherein when the rotation-side piston comes into contact with the brake pad, the rotation-side piston is pressed with a force greater than a reaction force generated in the connecting member in a direction away from the brake pad.

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