Disc brake

Abstract

This disc brake makes it possible to stabilize the position of a dust seal in a dust seal mounting groove and stabilize the roll-back amount of a piston while minimizing costs. A dust seal mounting groove 8 has: a cylinder hole opening-side surface 8a and a cylinder hole bottom-side surface 8b formed in a direction intersecting a cylinder axis CL1; and a mounting groove bottom surface 8c formed between the cylinder hole bottom-side surface 8b and the cylinder hole opening-side surface 8a. The mounting groove bottom surface 8c constitutes a regulating section and is formed as a conical surface in which the inner diameter around the cylinder axis CL1 of the dust seal mounting groove 8 gradually decreases toward the cylinder hole opening-side surface 8a. A separation section E1 in which a tip surface 10b and the cylinder hole opening-side surface 8a do not abut each other when not operating is provided between the tip surface 10b and the cylinder hole opening-side surface 8a.

Description

disc brake

[0001] The present invention relates to a disc brake, and more particularly to a disc brake in which a dust seal is attached to a cylinder bore that houses a piston, to prevent dust from entering the cylinder bore.

[0002] Conventionally, in disc brakes, a dust seal mounting groove is formed on the opening side of a cylinder bore provided in a caliper body, and a dust seal formed of an O-ring is mounted in this dust seal mounting groove to abut against the outer peripheral surface of the piston and prevent dust from entering the cylinder bore (see, for example, Patent Document 1).

[0003] Patent No. 6567926

[0004] Generally, the length of the dust seal mounting groove in the axial direction of the cylinder is made larger than the length of the dust seal in the axial direction of the cylinder, taking into account the thermal expansion of the dust seal. However, this margin makes it impossible to stabilize the position of the dust seal, resulting in an unstable amount of piston rollback.

[0005] Specifically, as shown in FIGS. 12 and 13 , a dust seal mounting groove 202 and a piston seal mounting groove 203 are formed in a cylinder bore 201, a dust seal 210 is mounted in the dust seal mounting groove 202, and a piston seal 211 is mounted in the piston seal mounting groove 203. The present invention will be described with reference to a disc brake in which a piston 204 inserted in the cylinder bore 201 is actuated to press and move a friction pad 205.

[0006] As shown in Fig. 12, when the dust seal 210 is mounted on the bottom side of the cylinder bore of the dust seal mounting groove 202, the dust seal 210 is dragged by the piston 204 during braking, causing it to protrude significantly from the dust seal mounting groove 202 toward the opening of the cylinder bore (protrusion amount: L1), as shown in Fig. 12 (A1). Accordingly, as shown in Fig. 12 (A2), the rollback amount L2 of the piston 204 when braking is released becomes large.

[0007] On the other hand, as shown in Figure 13, when the dust seal 210 is attached to the cylinder bore opening side of the dust seal attachment groove 202, the dust seal 210 is dragged by the piston 204 and protrudes from the dust seal attachment groove 202 toward the cylinder bore opening side during braking, as shown in Figure 13 (B1), but the amount of protrusion L3 is smaller than the amount of protrusion L1 when the dust seal 210 is attached to the cylinder bore bottom side of the dust seal attachment groove 202. Also, correspondingly, as shown in Figure 13 (B2), the amount of rollback L4 of the piston 204 when braking is released is smaller than the amount of rollback L2 when the dust seal 210 is attached to the cylinder bore bottom side of the dust seal attachment groove 202.

[0008] As such, the amount of rollback of the piston 204 changes depending on the installation position of the dust seal 210, so it is necessary to take measures to stabilize the installation position of the dust seal 210 and stabilize the amount of rollback, which could increase costs.

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a disc brake that can stabilize the position of the dust seal within the dust seal mounting groove and stabilize the amount of piston rollback while keeping costs down.

[0010] In order to achieve the above object, the dust seal mounting groove formed in the cylinder bore of the disc brake of the present invention has cylinder bore opening side surfaces and cylinder bore bottom side surfaces formed in a direction intersecting the cylinder axis, and a mounting groove bottom surface formed between the cylinder bore bottom side surfaces and the cylinder bore opening side surfaces, and the dust seal is mounted in a position spaced apart from at least one of the cylinder bore opening side surfaces and the cylinder bore bottom side surfaces when not in operation, and is characterized in that a restricting portion is provided in the dust seal mounting groove to restrict movement of the dust seal in the cylinder axial direction.

[0011] According to the disc brake of the present invention, by providing a restricting portion in the dust seal groove, it is possible to stabilize the position of the dust seal within the dust seal mounting groove and stabilize the amount of piston rollback while keeping costs down. Furthermore, because the dust seal is mounted in a position spaced apart from either the cylinder bore opening side surface or the cylinder bore bottom side surface when not in operation, the amount of rollback can be set as desired, taking into account the amount of dust seal protrusion during braking, which changes depending on the dust seal mounting position.

[0012] FIG. 1 is a schematic cross-sectional view of a main portion of a disc brake showing a first embodiment of the present invention. FIG. 1 is a cross-sectional view of the same disc brake. FIG. 2 is a schematic cross-sectional view of a main portion of a disc brake showing a second embodiment of the present invention. FIG. 3 is a schematic cross-sectional view of a main portion of a disc brake showing a third embodiment of the present invention. FIG. 4 is a schematic cross-sectional view of a main portion of a disc brake showing a fourth embodiment of the present invention. FIG. 5 is a schematic cross-sectional view of a main portion of a disc brake showing a fifth embodiment of the present invention. FIG. 6 is a schematic cross-sectional view of a main portion of a disc brake showing a sixth embodiment of the present invention. FIG. 7 is a schematic cross-sectional view of a main portion of a disc brake showing a seventh embodiment of the present invention. FIG. 8 is a schematic cross-sectional view of a main portion of a disc brake showing an eighth embodiment of the present invention. FIG. 9 is a schematic cross-sectional view of a main portion of a disc brake showing a ninth embodiment of the present invention. FIG. 10 is a schematic cross-sectional view of a main portion of a disc brake showing a tenth embodiment of the present invention. FIG. 11 is a schematic cross-sectional view of a main portion of a conventional disc brake. FIG.

[0013] 1 and 2 are diagrams showing a first embodiment of a disc brake according to the present invention. The disc brake 1 comprises a disc rotor 2 that rotates integrally with a wheel (not shown), a caliper body 3 that is attached to the vehicle body on one side of the disc rotor 2, and a pair of friction pads 4, 4 that are arranged opposite each other with the disc rotor 2 in between.

[0014] The caliper body 3 is made up of an acting portion 3a and a reaction portion 3b, which are arranged opposite each other on either side of the disc rotor 2, and a bridge portion 3c that connects these portions across the outer periphery of the disc rotor 2. A cylinder hole 3d that houses a piston 5 is provided in the acting portion 3a, and a reaction claw 3e is provided in the reaction portion 3b. A hydraulic chamber 6 is formed between the cylinder hole 3d and the bottom of the piston 5.

[0015] An annular piston seal mounting groove 7 is provided in the axial center of the inner peripheral surface of the cylinder bore 3d, and an annular dust seal mounting groove 8 is further provided closer to the cylinder bore opening than the piston seal mounting groove 7. A piston seal 9 is mounted in the piston seal mounting groove 7 and contacts the outer peripheral surface of the piston 5, causing the piston 5 to roll back by its restoring force. A dust seal 10 is mounted in the dust seal mounting groove 8 and contacts the outer peripheral surface of the piston 5 to prevent dust from entering the cylinder bore 3d.

[0016] The dust seal mounting groove 8 has a cylinder bore opening side surface 8a and a cylinder bore bottom side surface 8b formed in a direction intersecting the cylinder axis CL1, and a mounting groove bottom surface 8c formed between the cylinder bore bottom side surface 8b and the cylinder bore opening side surface 8a. In this embodiment, the mounting groove bottom surface 8c serves as a restricting portion that restricts movement of the dust seal 10 in the cylinder axial direction, and is formed as a conical surface whose inner diameter, centered on the cylinder axis CL1 of the dust seal mounting groove 8, gradually decreases toward the cylinder bore opening side surface 8a.

[0017] The dust seal 10 is formed as a square ring with a square cross section, with its outer peripheral surface 10a abutting against the mounting groove bottom surface 8c, its leading end surface 10b facing the cylinder bore opening side surface 8a, its rear end surface 10c facing the cylinder bore bottom side surface 8b, and its piston abutment surface 10d abutting against the piston 5. Furthermore, an annular recess 10e is formed in the center of the piston abutment surface 10d in the axial direction of the cylinder.

[0018] The dust seal 10 has its rear end surface 10c in contact with the cylinder bore bottom side surface 8b, and when not in operation, its front end surface 10b is spaced from the cylinder bore opening side surface 8a, forming a separation portion E1 between the front end surface 10b and the cylinder bore opening side surface 8a. Furthermore, because the mounting groove bottom surface 8c is formed as a conical surface as described above, the cylinder bore opening side of the dust seal 10 is compressed between the piston 5 and the mounting groove bottom surface 8c, and the outer circumferential surface 10a of the dust seal 10 and the mounting groove bottom surface 8c of the dust seal mounting groove 8 are in close contact with each other. This restricts movement of the dust seal 10 in the cylinder axial direction.

[0019] In this way, by forming the mounting groove bottom surface 8c of the dust seal 10 as a conical surface, axial movement of the dust seal 10 within the dust seal mounting groove 8 is restricted, thereby stabilizing the amount of rollback of the piston 5 while keeping costs down. In addition, the separation portion E1 enables the dust seal 10 to maintain a good mounting state in the dust seal mounting groove 8 even if it thermally expands. Furthermore, because the separation portion E1 is formed between the tip end surface 10b of the dust seal 10 and the cylinder bore opening side surface 8a, when the disc brake 1 is activated, the dust seal 10 is dragged by the piston 5 and protrudes a large amount from the dust seal mounting groove 8 toward the cylinder bore opening. This allows the dust seal 10, together with the piston seal 9, to compensate for the amount of rollback of the piston 5.

[0020] 3 to 11 show other embodiments of the present invention, and the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0021] 3 shows a second embodiment of the present invention. The dust seal mounting groove 20 has a cylinder bore opening side surface 20a and a cylinder bore bottom side surface 20b formed in a direction intersecting the cylinder axis CL1, and a mounting groove bottom surface 20c formed between the cylinder bore bottom side surface 20b and the cylinder bore opening side surface 20a. In this embodiment, the mounting groove bottom surface 20c forms a restricting portion, and, unlike the first embodiment, is formed as a conical surface whose inner diameter, centered on the cylinder axis CL1 of the dust seal mounting groove 20, gradually decreases toward the cylinder bore bottom side surface 20b.

[0022] The dust seal 10 has its leading end surface 10b in contact with the cylinder bore opening side surface 20a, and when not in operation, its rear end surface 10c is spaced from the cylinder bore bottom side surface 20b, forming a spaced portion E2 between the rear end surface 10c and the cylinder bore bottom side surface 20b. The cylinder bore bottom side of the dust seal 10 is compressed between the piston 5 and the mounting groove bottom surface 20c, and the outer circumferential surface 10a of the dust seal 10 and the mounting groove bottom surface 20c of the dust seal mounting groove 20 are in tight contact with each other. This restricts movement of the dust seal 10 in the cylinder axial direction.

[0023] Furthermore, in this embodiment, a separation portion E2 is formed between the rear end surface 10c of the dust seal 10 and the cylinder bore bottom side surface 20b, so that when the disc brake 1 is activated, the dust seal 10 is dragged by the piston 5 and only protrudes a small amount from the dust seal mounting groove 20 toward the cylinder bore opening. As a result, the dust seal 10 only slightly compensates for the rollback of the piston 5 compared to the first embodiment.

[0024] 4 shows a third embodiment of the present invention, in which the dust seal mounting groove 30 has a cylinder bore opening side surface 30a, a cylinder bore bottom side surface 30b, and a mounting groove bottom surface 30c. The cylinder bore opening side surface 30a is formed in a direction intersecting the cylinder axis CL1, and the mounting groove bottom surface 30c is formed parallel to the cylinder axis CL1.

[0025] In this embodiment, the cylinder bore bottom side surface 30b constitutes the restricting portion and is formed as a conical surface whose inner diameter, centered on the cylinder axis CL1 of the dust seal mounting groove 30, gradually decreases from the mounting groove bottom surface 30c toward the cylinder bore bottom side surface 30b. The length W1 of the mounting groove bottom surface 30c in the cylinder axial direction is the same as the length W1 of the outer peripheral surface 10a of the dust seal 10 in the cylinder axial direction.

[0026] As a result, the leading end surface 10b of the dust seal 10 abuts against the cylinder bore opening side surface 30a, and the rear end surface 10c on the outer peripheral side of the dust seal 10 abuts against the cylinder bore bottom side surface 30b (restriction portion), restricting axial movement of the dust seal 10. Furthermore, when not in operation, the rear end surface 10c is spaced apart from the cylinder bore bottom side surface 30b, forming a separation portion E3 between the rear end surface 10c and the cylinder bore bottom side surface 30b.

[0027] 5 shows a fourth embodiment of the present invention, in which the dust seal mounting groove 40 has a cylinder bore opening side surface 40a, a cylinder bore bottom side surface 40b, and a mounting groove bottom surface 40c. The cylinder bore bottom side surface 40b is formed in a direction intersecting the cylinder axis CL1, and the mounting groove bottom surface 40c is formed parallel to the cylinder axis CL1.

[0028] In this embodiment, the cylinder bore opening side surface 40a constitutes the restricting portion and is formed as a conical surface whose inner diameter, centered on the cylinder axis CL1 of the dust seal installation groove 40, gradually decreases from the installation groove bottom surface 40c toward the cylinder bore opening side surface 40a. The length W2 of the installation groove bottom surface 40c in the cylinder axial direction is the same as the length W2 of the outer peripheral surface 10a of the dust seal 10 in the cylinder axial direction.

[0029] As a result, the leading end surface 10b on the outer peripheral side of the dust seal 10 abuts against the cylinder bore opening side surface 40a (restriction portion), and the rear end surface 10c of the dust seal 10 abuts against the cylinder bore bottom side surface 40b, restricting axial movement of the dust seal 10. Furthermore, when not in operation, the leading end surface 10b is spaced apart from the cylinder bore opening side surface 40a, forming a separation portion E4 between the leading end surface 10b and the cylinder bore opening side surface 40a.

[0030] 6 shows a fifth embodiment of the present invention, in which the dust seal mounting groove 50 has a cylinder bore opening side surface 50a and a cylinder bore bottom side surface 50b formed in a direction intersecting the cylinder axis CL1, and a mounting groove bottom surface 50c formed parallel to the cylinder axis CL1. Furthermore, a restricting portion 50d is provided at the corner between the mounting groove bottom surface 50c and the cylinder bore bottom side surface 50b.

[0031] The restricting portion 50d is formed as a conical surface whose inner diameter gradually decreases from the mounting groove bottom surface 50c toward the cylinder bore bottom side surface 50b, centered on the cylinder axis CL1 of the dust seal mounting groove 50. The length W3 of the mounting groove bottom surface 50c in the cylinder axial direction is the same as the length W3 of the outer peripheral surface 10a of the dust seal 10 in the cylinder axial direction.

[0032] As a result, the leading end surface 10b of the dust seal 10 abuts against the cylinder bore opening side surface 50a, and the rear end surface 10c on the outer peripheral surface of the dust seal 10 abuts against the restricting portion 50d, restricting axial movement of the dust seal 10. Furthermore, when not in operation, the rear end surface 10c is spaced apart from the cylinder bore bottom side surface 50b, forming a separation portion E5 between the rear end surface 10c and the cylinder bore bottom side surface 50b.

[0033] 7 shows a sixth embodiment of the present invention, in which a dust seal mounting groove 60 has a cylinder bore opening side surface 60a and a cylinder bore bottom side surface 60b formed in a direction intersecting the cylinder axis CL1, and a mounting groove bottom surface 60c formed parallel to the cylinder axis CL1. Furthermore, a restricting portion 60d is provided at the corner between the mounting groove bottom surface 60c and the cylinder bore opening side surface 60a.

[0034] The restricting portion 60d is formed as a conical surface whose inner diameter gradually decreases from the mounting groove bottom surface 60c toward the cylinder bore opening side surface 60a, centered on the cylinder axis CL1 of the dust seal mounting groove 60. The length W4 of the mounting groove bottom surface 60c in the cylinder axial direction is the same as the length W4 of the outer peripheral surface 10a of the dust seal 10 in the cylinder axial direction.

[0035] As a result, the leading end surface 10b on the outer peripheral side of the dust seal 10 abuts against the restricting portion 60d, and the rear end surface 10c of the dust seal 10 abuts against the cylinder bore bottom side surface 60b, restricting axial movement of the dust seal 10. Furthermore, when not in operation, the leading end surface 10b is spaced apart from the cylinder bore opening side surface 60a, forming a separation portion E6 between the leading end surface 10b and the cylinder bore opening side surface 60a.

[0036] 8 shows a seventh embodiment of the present invention, in which a dust seal mounting groove 70 has a cylinder bore opening side surface 70a and a cylinder bore bottom side surface 70b formed in a direction intersecting the cylinder axis CL1, and a mounting groove bottom surface 70c formed parallel to the cylinder axis CL1. Furthermore, a first restricting portion 70d is provided at the corner between the mounting groove bottom surface 70c and the cylinder bore bottom side surface 70b, and a second restricting portion 70e is provided at the corner between the mounting groove bottom surface 70c and the cylinder bore opening side surface 70a.

[0037] The first restricting portion 70d is formed as a conical surface whose inner diameter, centered on the cylinder axis CL1 of the dust seal mounting groove 70, gradually decreases from the mounting groove bottom surface 70c toward the cylinder bore bottom side surface 70b. The second restricting portion 70e is formed as a conical surface whose inner diameter, centered on the cylinder axis CL1 of the dust seal mounting groove 70, gradually decreases from the mounting groove bottom surface 70c toward the cylinder bore opening side surface 70a. The length W5 of the mounting groove bottom surface 70c in the cylinder axial direction is the same as the length W5 of the outer peripheral surface 10a of the dust seal 10 in the cylinder axial direction.

[0038] As a result, the leading end surface 10b on the outer peripheral side of the dust seal 10 abuts against the second restricting portion 70e, and the rear end surface 10c on the outer peripheral side of the dust seal 10 abuts against the first restricting portion 70d, restricting movement of the dust seal 10 in the cylinder axial direction. Furthermore, when not in operation, the rear end surface 10c is spaced from the cylinder bore bottom side surface 70b, forming a first separation portion E7 between the rear end surface 10c and the cylinder bore bottom side surface 70b. Furthermore, when not in operation, the leading end surface 10b is spaced from the cylinder bore opening side surface 70a, forming a second separation portion E8 between the leading end surface 10b and the cylinder bore opening side surface 70a.

[0039] 9 shows an eighth embodiment of the present invention, in which a dust seal mounting groove 80 has a cylinder bore opening side surface 80a, a cylinder bore bottom side surface 80b, and a mounting groove bottom surface 80c. The cylinder bore opening side surface 80a is formed in a direction intersecting the cylinder axis CL1, and the mounting groove bottom surface 80c is formed parallel to the cylinder axis CL1.

[0040] The cylinder hole bottom side surface 80b constitutes the first regulating portion, and is formed as a conical surface whose inner diameter, centered on the cylinder axis CL1 of the dust seal mounting groove 80, gradually decreases from the mounting groove bottom surface 80c toward the cylinder hole bottom side surface 80b.

[0041] Furthermore, a second restricting portion 80d is provided at the corner between the cylinder bore opening side surface 80a and the mounting groove bottom surface 80c. The second restricting portion 80d is formed as a conical surface whose inner diameter, centered on the cylinder axis CL1 of the dust seal mounting groove 80, gradually decreases from the mounting groove bottom surface 80c toward the cylinder bore opening side surface 80a.

[0042] The length W6 of the mounting groove bottom surface 80c in the cylinder axial direction is the same as the length W6 of the outer peripheral surface 10a of the dust seal 10 in the cylinder axial direction.

[0043] As a result, the leading end surface 10b on the outer peripheral side of the dust seal 10 abuts against the second restricting portion 80d, and the trailing end surface 10c on the outer peripheral side of the dust seal 10 abuts against the cylinder bore bottom side surface 80b (first restricting portion), restricting movement of the dust seal 10 in the cylinder axial direction. Furthermore, when not in operation, the trailing end surface 10c is spaced apart from the cylinder bore bottom side surface 80b, forming a first separation portion E9 between the rear end surface 10c and the cylinder bore bottom side surface 80b. Furthermore, when not in operation, the leading end surface 10b is spaced apart from the cylinder bore opening side surface 80a, forming a second separation portion E10 between the leading end surface 10b and the cylinder bore opening side surface 80a.

[0044] 10 shows a ninth embodiment of the present invention, in which a dust seal mounting groove 90 has a cylinder bore opening side surface 90a, a cylinder bore bottom side surface 90b, and a mounting groove bottom surface 90c. The cylinder bore bottom side surface 90b is formed in a direction intersecting the cylinder axis CL1, and the mounting groove bottom surface 90c is formed parallel to the cylinder axis CL1.

[0045] The cylinder hole opening side surface 90a constitutes the first regulating portion, and is formed as a conical surface whose inner diameter, centered on the cylinder axis CL1 of the dust seal mounting groove 90, gradually decreases from the mounting groove bottom surface 90c toward the cylinder hole opening side surface 90a.

[0046] Furthermore, a second restricting portion 90d is provided at the corner between the cylinder bore bottom side surface 90b and the mounting groove bottom surface 90c. The second restricting portion 90d is formed as a conical surface whose inner diameter, centered on the cylinder axis CL1 of the dust seal mounting groove 90, gradually decreases from the mounting groove bottom surface 90c toward the cylinder bore bottom side surface 90b.

[0047] The length W7 of the mounting groove bottom surface 90c in the cylinder axial direction is the same as the length W7 of the outer peripheral surface 10a of the dust seal 10 in the cylinder axial direction.

[0048] As a result, the leading end surface 10b on the outer peripheral side of the dust seal 10 abuts against the cylinder bore opening side surface 90a (first restricting portion), and the trailing end surface 10c on the outer peripheral side of the dust seal 10 abuts against the second restricting portion 90d, restricting movement of the dust seal 10 in the cylinder axial direction. Furthermore, when not in operation, the trailing end surface 10c is spaced apart from the cylinder bore bottom side surface 90b, forming a first separation portion E11 between the rear end surface 10c and the cylinder bore bottom side surface 90b. Furthermore, when not in operation, the leading end surface 10b is spaced apart from the cylinder bore opening side surface 90a, forming a second separation portion E12 between the leading end surface 10b and the cylinder bore opening side surface 90a.

[0049] Figure 11 shows a tenth embodiment of the present invention, in which the dust seal mounting groove 100 has a cylinder bore opening side surface 100a and a cylinder bore bottom side surface 100b formed in a direction intersecting the cylinder axis CL1, and a mounting groove bottom surface 100c formed between the cylinder bore bottom side surface 100b and the cylinder bore opening side surface 100a.

[0050] The mounting groove bottom surface 100c constitutes a regulating portion and has a first conical surface 100d whose inner diameter, centered on the cylinder axis CL1 of the dust seal mounting groove 100, gradually decreases from the cylinder axial direction center portion P1 of the mounting groove bottom surface 100c toward the cylinder bore bottom side surface 100b, and a second conical surface 100e whose inner diameter, centered on the cylinder axis CL1 of the dust seal mounting groove 100, gradually decreases from the cylinder axial direction center portion P1 of the mounting groove bottom surface 100c toward the cylinder bore opening side surface 100a.

[0051] The dust seal 10 is mounted in the dust seal mounting groove 100 by aligning the cylinder axial center portion with the cylinder axial center portion P1 of the mounting groove bottom surface 100c.

[0052] As a result, the cylinder bore bottom side and cylinder bore opening side of the dust seal 10 are compressed between the piston 5 and the first conical surface 100d and second conical surface 100e, and the outer peripheral surface 10a of the dust seal 10 and the mounting groove bottom surface 100c of the dust seal mounting groove 100 are in close contact with each other, restricting movement of the dust seal 10 in the cylinder axial direction. Furthermore, when not in operation, the rear end surface 10c is spaced from the cylinder bore bottom side surface 100b, forming a separation portion E13 between the rear end surface 10c and the cylinder bore bottom side surface 100b. Furthermore, when not in operation, the front end surface 10b is spaced from the cylinder bore opening side surface 100a, forming a separation portion E14 between the front end surface 10b and the cylinder bore opening side surface 100a.

[0053] As in the above-described embodiments, by providing a restricting portion in the dust seal mounting groove, the dust seal can be positioned at any position in the dust seal groove while being restricted from moving in the axial direction of the cylinder, thereby stabilizing the amount of piston rollback while keeping costs down.Furthermore, the amount of rollback can be set as desired, taking into account the amount of dust seal protrusion during braking, which changes depending on the dust seal mounting position.

[0054] As described above, the disc brake of the present invention is not limited to one in which an acting part with a piston and a reaction part with a reaction claw are arranged opposite each other on both sides of the disc rotor, but may also be one in which acting parts with pistons are arranged opposite each other on both sides of the disc rotor, and the number of pistons is also arbitrary.

[0055] DESCRIPTION OF SYMBOLS 1...Disc brake, 2...Disc rotor, 3...Caliper body, 3a...Action portion, 3b...Reaction portion, 3c...Bridge portion, 3d...Cylinder bore, 3e...Reaction claw, 4...Friction pad, 5...Piston, 6...Hydraulic chamber, 7...Piston seal mounting groove, 8...Dust seal mounting groove, 8a...Cylinder bore opening side surface, 8b...Cylinder bore bottom side surface, 8c...Mounting groove bottom surface (restriction portion), 9...Piston seal, 10...Dust seal, 10a...Outer circumferential surface, 10b...Front end surface, 10c...Rear end surface, 10d...Piston abutment surface, 10e...Annular recess 20...Dust seal mounting groove, 20c...Mounting groove bottom surface (restriction portion) 30...Dust seal mounting groove, 30b...Cylinder bore bottom side surface (restriction portion) 40...Dust seal mounting groove, 40a...Cylinder bore opening side surface (restriction portion) 50...Dust seal mounting groove, 50d...Restriction portion 60...Dust seal mounting groove, 60d...Restriction portion 70...Dust seal mounting groove, 70d...First restriction portion, 70e...Second restriction portion 80...Dust seal mounting groove, 80b...Cylinder bore bottom side surface (first restriction portion), 80d...Second restriction portion 90...Dust seal mounting groove, 90a...Cylinder bore opening side surface (first restriction portion), 90d...Second restriction portion 100...Dust seal mounting groove, 100c...Mounting groove bottom surface (restriction portion)

Claims

1. A disc brake comprising: a piston seal mounted in a cylinder bore formed in a caliper body; a dust seal mounting groove formed on the cylinder bore opening side of the piston seal; and a dust seal mounted in the dust seal mounting groove, which abuts against an outer peripheral surface of a piston inserted into the cylinder bore to prevent dust from entering the cylinder bore, the dust seal mounting groove has a cylinder bore opening side surface and a cylinder bore bottom side surface formed in a direction intersecting the cylinder axis, and a mounting groove bottom surface formed between the cylinder bore bottom side surface and the cylinder bore opening side surface, The dust seal is attached at a position spaced apart from at least one of the cylinder bore opening side surface and the cylinder bore bottom side surface when the dust seal is not in operation, and A disc brake characterized in that the dust seal mounting groove is provided with a restricting portion that restricts movement of the dust seal in the cylinder axial direction.

2. The restriction portion is 2. The disc brake according to claim 1, wherein the mounting groove bottom surface is provided between the mounting groove bottom surface and at least one of the cylinder hole opening side surface and the cylinder hole bottom side surface.

3. The restriction portion is a corner between the bottom surface of the mounting groove and the side surface of the opening of the cylinder bore, or a corner between the bottom surface of the mounting groove and the side surface of the bottom of the cylinder bore, 2. The disc brake according to claim 1, wherein the dust seal mounting groove is formed as a conical surface whose inner diameter, centered on the cylinder axis, gradually decreases from the mounting groove bottom surface toward at least one of the cylinder bore opening side surface and the cylinder bore bottom side surface.

4. The restriction portion is 2. The disc brake according to claim 1, wherein the bottom surface of the mounting groove is formed as a conical surface whose inner diameter, centered on the cylinder axis of the dust seal mounting groove, gradually decreases toward at least one of the cylinder bore opening side surface and the cylinder bore bottom side surface.

5. The restriction portion is 2. The disc brake according to claim 1, wherein the cylinder bore bottom side surface is formed as a conical surface whose inner diameter, centered on the cylinder axis of the dust seal mounting groove, gradually decreases from the mounting groove bottom surface side toward the cylinder bore bottom side surface.

6. The restriction portion is 2. The disc brake according to claim 1, wherein the cylinder bore opening side surface is formed by a conical surface whose inner diameter, centered on the cylinder axis of the dust seal mounting groove, gradually decreases from the mounting groove bottom surface side toward the cylinder bore opening side surface.

7. The restriction portion is a first restricting portion formed by a conical surface on the cylinder bore bottom side surface, the inner diameter of which, centered on the cylinder axis of the dust seal mounting groove, gradually decreases from the mounting groove bottom side surface toward the cylinder bore bottom side surface; a second restricting portion formed by a conical surface, the second restricting portion being provided at a corner between the bottom surface of the mounting groove and the side surface of the cylinder bore opening, the second restricting portion having an inner diameter that gradually decreases from the bottom surface of the mounting groove toward the side surface of the cylinder bore opening, the inner diameter of the dust seal mounting groove being centered on the cylinder axis; 2. The disc brake according to claim 1, further comprising:

8. The restriction portion is a first restricting portion formed by a conical surface on the cylinder bore opening side surface, the inner diameter of which, centered on the cylinder axis of the dust seal installation groove, gradually decreases from the bottom surface of the installation groove toward the cylinder bore opening side surface; a second restricting portion formed by a conical surface, the second restricting portion being provided at a corner between the bottom surface of the mounting groove and the bottom side surface of the cylinder bore, the second restricting portion having an inner diameter that gradually decreases from the bottom surface of the mounting groove toward the bottom side surface of the cylinder bore, the inner diameter being centered on the cylinder axis of the dust seal mounting groove; 2. The disc brake according to claim 1, further comprising:

9. 2. The disc brake according to claim 1, wherein the dust seal is mounted at a position spaced apart from a side surface of the cylinder bore opening when the dust seal is not in operation.

10. The dust seal is 2. The disc brake according to claim 1, wherein an outer peripheral surface that abuts against the bottom surface of the mounting groove, a leading end surface that faces the side surface of the cylinder bore opening, and a rear end surface that faces the side surface of the cylinder bore bottom are all flat and have a square cross section.