Brake caliper

Abstract

To provide a brake caliper which can reduce dragging torque while suppressing a generation of rattle.SOLUTION: A brake caliper according to an embodiment includes: a first member which is one of a caliper body and a mount; a pin which projects from the first member; a second member on which a hole for storing a part of the pin is stored, and which has a first inner peripheral face directed to the pin at a position apart from the pin, and is the other of the caliper body and the mount; and an elastically deformable boot which has an annular part attached to the second member and surrounding the pin, a telescopic part connected to the annular part, covering the pin outside of the hole, and expanding and retracting according to a movement of the caliper body with respect to the mount, a second inner peripheral face provided on the annular part, apart from the pin, and directed to the pin at a position closer to the pin than the first inner peripheral face, and a projection projecting from the second inner peripheral face and supporting the pin.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION An embodiment of the present invention relates to a brake caliper. [Background technology]

[0002] Conventionally, a pin is sometimes provided on the caliper body to guide the relative movement between the caliper body and the mount. The pin is inserted into a hole provided in the mount and moves along the hole when the caliper body and the mount move relative to each other.

[0003] The pin may be held at a position spaced apart from the inner circumferential surface of the hole by, for example, a spring, which holds the pin in place to prevent rattle from occurring due to collision between the pin and the inner circumferential surface of the hole (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-027904 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the conventional configuration, the spring presses against the outer circumferential surface of the pin, which can cause drag torque when the pin moves along the hole due to sliding resistance between the spring and the pin.

[0006] Therefore, the present invention has been made in consideration of the above, and provides a brake caliper that can suppress the occurrence of rattle and reduce drag torque. [Means for solving the problem]

[0007] As an example, a brake caliper according to an embodiment of the present invention includes a first member which is one of a caliper body that holds a piston movably in a first direction and a second direction opposite to the first direction, and a mount that holds the caliper body movably in the first direction and the second direction, a pin protruding from the first member in the first direction, and a first inner circumferential surface that is provided with a hole that receives a part of the pin and faces the pin at a position spaced from the pin, and a front portion of the caliper body and a mount that holds the caliper body movably in the first direction and the second direction. The caliper includes a second member, which is the other of the mount, a ring portion attached to the second member and surrounding the pin, an expandable portion connected to the ring portion, covering the pin outside the hole, and expanding and contracting in response to movement of the caliper body relative to the mount, a second inner circumferential surface provided on the ring portion, spaced from the pin, facing the pin at a position closer to the pin than the first inner circumferential surface, and a protrusion protruding from the second inner circumferential surface and supporting the pin, the boot being elastically deformable. Thus, for example, the pin compresses the protrusion by moving toward the first inner circumferential surface. As the pin moves further, it contacts the second inner circumferential surface before contacting the first inner circumferential surface. That is, the pin compresses not only the protrusion but also the ring portion. By compressing both the protrusion and the ring portion, the boot applies a stronger reaction force to the pin, preventing the pin from colliding with the first inner circumferential surface. This allows the brake caliper to suppress rattle caused by the pin colliding with the first inner circumferential surface. On the other hand, when the pin is positioned in the normal position, the protrusion contacts the pin, but the second inner circumferential surface is spaced apart from the pin. In other words, the contact area between the pin and the boot is small. As a result, the boot can reduce drag torque generated by sliding resistance between the boot and the pin when the pin moves in the first direction or the second direction. Therefore, the brake caliper can suppress rattle and reduce drag torque. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view schematically showing a disc brake according to a first embodiment. [Figure 2]FIG. 2 is a cross-sectional view showing a part of the disc brake of the first embodiment. [Figure 3] FIG. 3 is a cross-sectional view schematically showing a part of the disc brake of the first embodiment taken along line F3-F3 in FIG. [Figure 4] FIG. 4 is a cross-sectional view showing a part of the brake caliper of the first embodiment taken along line F4-F4 in FIG. [Figure 5] FIG. 5 is a cross-sectional view showing the mounting groove, a part of the pin, and the ring portion of the first embodiment. [Figure 6] FIG. 6 is a cross-sectional view showing the mounting groove, a portion of the pin that has moved, and a deformed ring portion of the first embodiment. [Figure 7] FIG. 7 is a cross-sectional view showing a part of a brake caliper according to the second embodiment. [Figure 8] FIG. 8 is a cross-sectional view showing a boot and a pin according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] (First embodiment) The first embodiment will be described below with reference to FIGS. 1 to 6. In this specification, components according to the embodiment and descriptions of the components may be described using multiple expressions. The components and their descriptions are merely examples and are not limited by the expressions in this specification. The components may also be identified by names different from those in this specification. Furthermore, the components may also be described using expressions different from those in this specification.

[0010] In the following description, "suppress" is defined as, for example, preventing an event, action, or influence from occurring, or reducing the severity of an event, action, or influence. Also, in the following description, "restrict" is defined as, for example, preventing movement or rotation, or allowing movement or rotation within a predetermined range and preventing movement or rotation beyond the predetermined range.

[0011] FIG. 1 is a perspective view schematically illustrating a disc brake 10 according to a first embodiment. The disc brake 10 according to this embodiment is a floating-type disc brake. However, the disc brake 10 may be another type of disc brake. The disc brake 10 includes a disc rotor 11 and a brake caliper 12.

[0012] The disc rotor 11 is formed in a disk shape that can rotate around a rotation axis Axr. The rotation axis Axr is, for example, the central axis of the axle of the vehicle 1 on which the disc brake 10 is mounted. However, the rotation axis Axr is not limited to this example.

[0013] For convenience, the axial direction is defined herein as the direction along the rotation axis Axr. The axial direction includes a first direction D1 along the rotation axis Axr and a second direction D2 opposite to the first direction D1. Note that the first direction D1 and the second direction D2 are not limited to directions along the rotation axis Axr.

[0014] Fig. 2 is a cross-sectional view showing a portion of the disc brake 10 of the first embodiment. As shown in Fig. 2, the disc rotor 11 is fixed to a hub 13 that supports a wheel. The hub 13 is rotatably supported by a knuckle 14 of a suspension that is supported on the body of the vehicle 1. The disc rotor 11 rotates integrally with the hub 13 and the wheel around a rotation axis Axr.

[0015] The disc rotor 11 has two side surfaces 11a. The side surfaces 11a are formed to be substantially flat and face in the axial direction. In other words, the rotation axis Axr extends in a direction perpendicular to the side surfaces 11a. The two side surfaces 11a are located on opposite sides of each other.

[0016] Fig. 3 is a cross-sectional view schematically showing a part of the disc brake 10 of the first embodiment taken along line F3-F3 in Fig. 1. The brake caliper 12 has two brake pads 21, a piston 22, and a movable part 23 shown in Fig. 3, and a fixed part 24 and two boots 25 shown in Fig. 1.

[0017] As shown in Fig. 3, the brake pads 21 are held by a movable part 23 so as to be movable in the axial direction. The two brake pads 21 are arranged side by side with a gap in the axial direction. The disc rotor 11 is disposed between the two brake pads 21. The disc brake 10 applies brakes to the disc rotor 11 and the wheel by pressing the brake pads 21 against the side surface 11a of the disc rotor 11.

[0018] The piston 22 is formed in a generally cylindrical shape extending in the axial direction. However, the shape of the piston 22 is not limited to this example. Furthermore, the number of pistons 22 is not limited to one, and may be two or more.

[0019] The movable part 23 has a caliper body 31 shown in Fig. 3, and two pins 32 and two bolts 33 shown in Fig. 1. The caliper body 31 is an example of a first member. Note that the number of pins 32 and bolts 33 is not limited to two, and may be one, or three or more.

[0020] The caliper body 31 has a retaining portion 41, a claw portion 42, and a connecting portion 43 shown in Fig. 3, and two mounting portions 44 shown in Fig. 1. The retaining portion 41, the claw portion 42, the connecting portion 43, and the mounting portion 44 are integrally formed. Note that at least some of the retaining portion 41, the claw portion 42, the connecting portion 43, and the mounting portion 44 may be separate parts from the other portions.

[0021] 3, a cylinder chamber 45 that opens toward a first direction D1 is provided in the holding portion 41. The piston 22 is accommodated in the cylinder chamber 45 so as to be capable of reciprocating in the axial direction. The holding portion 41 of the caliper body 31 holds the piston 22 so as to be movable in the first direction D1 and the second direction D2.

[0022] A piston seal 47 is attached to the holder 41. The piston seal 47 is formed in a substantially annular shape from, for example, synthetic rubber. The piston seal 47 seals the gap between the piston 22 and the holder 41 liquid-tightly.

[0023] The claw portion 42 is spaced apart in the first direction D1 from the holding portion 41. The disc rotor 11 and the two brake pads 21 are disposed between the piston 22 held by the holding portion 41 and the claw portion 42. The connecting portion 43 connects the holding portion 41 and the claw portion 42 to each other.

[0024] For example, when the driver of the vehicle 1 depresses the brake pedal to perform a braking operation, hydraulic oil is supplied to the cylinder chamber 45, and the hydraulic pressure in the cylinder chamber 45 increases. The hydraulic pressure causes the piston 22 to move in the first direction D1 and press one brake pad 21 against one side surface 11a of the disc rotor 11.

[0025] When the piston 22 presses one of the brake pads 21 against the disc rotor 11, the reaction force moves the movable part 23 in the second direction D2. This causes the claw portion 42 to press the other brake pad 21 against the other side surface 11a of the disc rotor 11. The disc brake 10 generates a braking force by pressing the two brake pads 21 against the disc rotor 11.

[0026] 1, the attachment portion 44 protrudes from the holding portion 41 in a direction substantially perpendicular to the axial direction. The two attachment portions 44 protrude in opposite directions from the holding portion 41. However, the attachment portions 44 are not limited to this example.

[0027] Figure 4 is a cross-sectional view showing a portion of the brake caliper 12 of the first embodiment taken along line F4-F4 in Figure 1. As shown in Figure 4, the mounting portion 44 has a mounting surface 44a. The mounting surface 44a is formed to be substantially flat and faces the first direction D1. Furthermore, a through hole 48 is provided in the mounting portion 44. The through hole 48 passes through the mounting portion 44 in a substantially axial direction and opens to the mounting surface 44a.

[0028] Each of the two pins 32 is attached to the corresponding mounting portion 44 by, for example, a bolt 33 so as to protrude in the first direction D1 from the mounting surface 44a of the corresponding mounting portion 44. In this manner, the pin 32 protrudes in the first direction D1 from the caliper body 31. Note that the pin 32 may be formed integrally with the caliper body 31.

[0029] The pins 32 are made of, for example, metal. Each of the two pins 32 is formed in a generally cylindrical shape extending in the axial direction. In other words, the two pins 32 extend generally parallel to the rotation axis Axr. Note that the material and shape of the pins 32 are not limited to this example. Furthermore, the shapes of the two pins 32 may be different from each other.

[0030] For convenience, the terms radial direction and circumferential direction are defined herein. The radial direction is a direction perpendicular to the central axis Axc of the pin 32. The circumferential direction is a direction around the central axis Axc. Furthermore, since the pin 32 extends in the axial direction, the axial direction is a direction along the rotation axis Axr as well as a direction along the central axis Axc.

[0031] Note that even if the pin 32 has a shape other than cylindrical, the central axis Axc, the axial direction, the radial direction, and the circumferential direction can be defined. When the pin 32 has a shape other than cylindrical, the axial direction is the direction in which the piston 22 is movable and includes the first direction D1 and the second direction D2. The radial direction is a direction perpendicular to the first direction D1 and the second direction D2 and includes the direction facing inward of the pin 32 (radial inward) and the direction facing outward of the pin 32 (radial outward).

[0032] Each of the two pins 32 has a base 51 and a sliding portion 52. The base 51 and the sliding portion 52 are formed in a generally cylindrical shape extending in the axial direction. The diameter of the base 51 is larger than the diameter of the sliding portion 52. The base 51 and the sliding portion 52 are arranged concentrically on the central axis Axc.

[0033] The base 51 abuts against the mounting surface 44a of the mounting portion 44. Note that other members may be interposed between the base 51 and the mounting surface 44a. A screw hole 55 and a mounting groove 56 are provided in the base 51. The screw hole 55 communicates with the through hole 48 of the mounting portion 44. The bolt 33 passes through the through hole 48 and is fitted into the screw hole 55, thereby attaching the pin 32 to the mounting portion 44. The mounting groove 56 is provided around the entire circumference of the base 51 in the circumferential direction.

[0034] The sliding portion 52 protrudes from the base portion 51 in the first direction D1. In the axial direction, the sliding portion 52 is longer than the base portion 51. The sliding portion 52 has an outer peripheral surface 52a. The outer peripheral surface 52a is formed in a substantially cylindrical shape extending along the central axis Axc and faces radially outward.

[0035] The fixed component 24 has a mount 61. The mount 61 is an example of a second member. The mount 61 is fixed to the knuckle 14. In other words, the mount 61 is fixed to the body of the vehicle 1.

[0036] The mount 61 holds the caliper body 31 movably in the axial direction (first direction D1 and second direction D2). Therefore, the movable part 23 including the caliper body 31 can be moved by the hydraulic pressure of the cylinder chamber 45, as described above.

[0037] The mount 61 has an outer surface 61a. The outer surface 61a faces the mounting surface 44a of the mounting portion 44 via a gap. The outer surface 61a is a part of the entire outer surface of the mount 61. The mount 61 is provided with a guide hole 62 that opens to the outer surface 61a. The guide hole 62 is an example of a hole.

[0038] The guide hole 62 is a bottomed hole recessed from the outer surface 61a in the first direction D1. In other words, the guide hole 62 extends in the axial direction. The guide hole 62 may pass through the mount 61. The guide hole 62 has a substantially circular cross section. Under normal circumstances, the guide hole 62 is provided on the central axis Axc and concentric with the base 51 and sliding portion 52 of the pin 32.

[0039] The mount 61 further has an inner circumferential surface 62a of the guide hole 62. The inner circumferential surface 62a is an example of a first inner circumferential surface. The inner circumferential surface 62a forms (defines, defines) the guide hole 62. The inner circumferential surface 62a is formed in a substantially cylindrical shape extending from the outer surface 61a in the first direction D1 and faces radially inward. In other words, the inner circumferential surface 62a faces the central axis Axc. The diameter of the inner circumferential surface 62a is larger than the diameter of the outer circumferential surface 52a of the sliding portion 52.

[0040] The base 51 of the pin 32 is located outside the guide hole 62. On the other hand, the sliding portion 52, which is a part of the pin 32, is at least partially housed (inserted) in the corresponding guide hole 62. Therefore, the inner peripheral surface 62a of the guide hole 62 surrounds the sliding portion 52 and faces the outer peripheral surface 52a of the sliding portion 52 at a position spaced apart from the outer peripheral surface 52a. Note that the inner peripheral surface 62a may be temporarily in contact with the outer peripheral surface 52a.

[0041] An attachment groove 65 is provided in the inner circumferential surface 62a. The attachment groove 65 is part of the guide hole 62. The attachment groove 65 is recessed radially outward from the inner circumferential surface 62a. The attachment groove 65 is provided around the entire circumferential circumference of the inner circumferential surface 62a. The attachment groove 65 is located near the outer surface 61a.

[0042] 5 is a cross-sectional view showing the mounting groove 65, a portion of the pin 32, and the ring portion 71 of the first embodiment. As shown in FIG. 5, the mount 61 further has a bottom surface 65a of the mounting groove 65, two side surfaces 65b and 65c, and an edge surface 65d. The side surface 65b is an example of a first side surface. The side surface 65c is an example of a second side surface. The bottom surface 65a, the side surfaces 65b and 65c, and the edge surface 65d form (define, define) the mounting groove 65.

[0043] The bottom surface 65a is provided at the radially outer end of the mounting groove 65 and is formed in a cylindrical shape extending substantially in the axial direction. The bottom surface 65a is located farther away from the sliding portion 52 than the inner peripheral surface 62a and faces the outer peripheral surface 52a of the sliding portion 52.

[0044] The side surface 65b extends radially inward from the end of the bottom surface 65a in the first direction D1. The side surface 65b is formed to be approximately flat and faces the second direction D2. The side surface 65c extends radially inward from the end of the bottom surface 65a in the second direction D2. The side surface 65c is formed to be approximately flat and faces the first direction D1. The two side surfaces 65b, 65c face each other.

[0045] The edge surface 65d is provided between the radially inner end of the side surface 65c and the outer surface 61a of the mount 61. The edge surface 65d is formed in a cylindrical shape extending substantially in the axial direction. The edge surface 65d is closer to the sliding portion 52 than the bottom surface 65a and is farther away from the sliding portion 52 than the inner peripheral surface 62a. The edge surface 65d faces the outer peripheral surface 52a of the sliding portion 52.

[0046] 4, each of the two boots 25 covers the corresponding pin 32 and closes the gap between the outer peripheral surface 52a of the sliding portion 52 and the inner peripheral surface 62a of the guide hole 62. As a result, the boots 25 prevent moisture and dust from adhering to the sliding portion 52 or entering the guide hole 62, and thus prevent the sliding portion 52 from rusting.

[0047] The boot 25 is made of an elastomer such as ethylene propylene diene rubber (EPDM) and is elastically deformable. However, the boot 25 may be made of other materials. The boot 25 has two ring portions 71 and 72, an elastic portion 73, and a protrusion 74.

[0048] The ring portion 71 is provided, for example, at an end of the boot 25 in the first direction D1. The ring portion 71 is fitted into the guide hole 62 and attached to the mount 61. For example, the ring portion 71 is fitted into the attachment groove 65.

[0049] 5, the ring portion 71 is disposed between two side surfaces 65b, 65c of the mounting groove 65. When the side surfaces 65b, 65c come into contact with the ring portion 71, they restrict the ring portion 71 from moving in the axial direction.

[0050] The ring portion 71 is formed in a substantially circular ring shape around the central axis Axc. Note that the shape of the ring portion 71 is not limited to this example. The sliding portion 52 of the pin 32 is disposed inside the ring portion 71. Therefore, the ring portion 71 is located between the mount 61 and the sliding portion 52, and surrounds the sliding portion 52 of the pin 32.

[0051] The ring portion 71 has an outer peripheral surface 71a, an inner peripheral surface 71b, and two side surfaces 71c and 71d. In other words, the outer peripheral surface 71a, the inner peripheral surface 71b, and the side surfaces 71c and 71d are provided on the ring portion 71. The inner peripheral surface 71b is an example of a second inner peripheral surface.

[0052] The outer peripheral surface 71a and the inner peripheral surface 71b are generally cylindrical curved surfaces extending generally in the axial direction. The outer peripheral surface 71a faces radially outward. The outer peripheral surface 71a of the ring portion 71 contacts the bottom surface 65a of the mounting groove 65. The inner peripheral surface 71b is located on the opposite side of the outer peripheral surface 71a. The inner peripheral surface 71b of the ring portion 71 faces the outer peripheral surface 52a of the sliding portion 52.

[0053] In a natural state in which the boot 25 is removed from the brake caliper 12 and is not subjected to external forces, the diameter of the outer peripheral surface 71a of the ring portion 71 is larger than the diameter of the bottom surface 65a of the mounting groove 65. Therefore, the outer peripheral surface 71a of the ring portion 71 is in liquid-tight contact with the bottom surface 65a of the mounting groove 65, and it is possible to prevent moisture and dust from entering the guide hole 62.

[0054] The side surface 71c is provided between the end of the outer peripheral surface 71a and the end of the inner peripheral surface 71b in the first direction D1. The side surface 71c of the ring portion 71 faces the side surface 65b of the mounting groove 65. The side surface 71d is located on the opposite side of the side surface 71c. The side surface 71d of the ring portion 71 faces the side surface 65c of the mounting groove 65.

[0055] 4, the ring portion 72 is provided, for example, at an end of the boot 25 in the second direction D2. The ring portion 72 is formed in a substantially annular shape around the central axis Axc. However, the position and shape of the ring portion 72 are not limited to this example.

[0056] The ring portion 72 is attached to the movable part 23. For example, the ring portion 72 is fitted into the attachment groove 56 of the pin 32. As a result, the base portion 51 of the pin 32 is disposed inside the ring portion 72. The ring portion 72 is in liquid-tight contact with the base portion 51.

[0057] The base 51 holds the ring portion 72 so as to restrict axial movement of the ring portion 72. Therefore, the ring portion 72 can move integrally with the movable part 23 including the caliper body 31 and the pin 32 in the first direction D1 and the second direction D2 relative to the fixed part 24. The ring portion 72 is located outside the guide hole 62 and is spaced apart from the outer surface 61 a of the mount 61 in the second direction D2.

[0058] The stretchable portion 73 is provided between the ring portion 71 and the ring portion 72. As shown in FIG. 5, an end of the stretchable portion 73 in the first direction D1 is connected to a side surface 71d of the ring portion 71. The stretchable portion 73 extends from the side surface 71d of the ring portion 71 through a gap between the outer peripheral surface 52a of the sliding portion 52 and the edge surface 65d of the mounting groove 65 to the outside of the guide hole 62. As shown in FIG. 4, an end of the stretchable portion 73 in the second direction D2 is connected to the ring portion 72. Note that the stretchable portion 73 may be connected to the ring portion 71 via another portion, or may be connected to the ring portion 72 via another portion.

[0059] The pin 32 is disposed inside the expandable portion 73. The expandable portion 73 covers the outer peripheral surface 52a of the sliding portion 52 outside the guide hole 62. The base portion 51 may be exposed and not covered by the expandable portion 73. Furthermore, inside the guide hole 62, the expandable portion 73 may further cover the outer peripheral surface 52a.

[0060] The expansion / contraction portion 73 can be elastically deformed to expand and contract in the axial direction in response to movement of the caliper body 31 relative to the mount 61. The expansion / contraction portion 73 in this embodiment is, for example, a bellows, and is formed to be expandable and contractible in the axial direction.

[0061] As described above, when braking is performed by the disc brake 10, the piston 22 presses the brake pad 21 against the disc rotor 11, and the reaction force moves the movable part 23 in the second direction D2. As a result, the movable part 23, including the caliper body 31 and the pin 32, moves in the second direction D2 relative to the mount 61.

[0062] As the movable part 23 moves in the second direction D2, the ring part 72 attached to the base part 51 also moves in the second direction D2 relative to the ring part 71. As a result, the distance between the ring part 71 and the ring part 72 increases, and the expandable part 73 extends in the axial direction.

[0063] On the other hand, when the driver of the vehicle 1 releases the braking operation, the hydraulic pressure in the cylinder chamber 45 decreases. As the hydraulic pressure decreases, the reaction force that moves the movable part 23 in the second direction D2 is also released. As a result, the movable part 23, including the caliper body 31 and the pin 32, moves in the first direction D1 relative to the mount 61.

[0064] When the movable part 23 moves in the first direction D1, the ring part 72 attached to the base part 51 also moves in the first direction D1 relative to the ring part 71. As a result, the distance between the ring part 71 and the ring part 72 decreases, and the expandable part 73 decreases in the axial direction.

[0065] 5, the protrusion 74 protrudes from the inner circumferential surface 71b of the ring portion 71 toward the outer circumferential surface 52a of the sliding portion 52. The protrusion 74 has an inner circumferential surface 74a. The inner circumferential surface 74a is a substantially cylindrical curved surface provided around the central axis Axc. The inner circumferential surface 74a of the protrusion 74 faces the outer circumferential surface 52a of the sliding portion 52.

[0066] Grooves 75 are provided on the inner circumferential surface 74a of the protrusion 74. The grooves 75 are provided around the entire periphery of the inner circumferential surface 74a in the circumferential direction. For example, grease is accommodated in the grooves 75. However, the grooves 75 are not limited to this example.

[0067] In a natural state, the diameter of the inner circumferential surface 74a of the protrusion 74 is smaller than the diameter of the outer circumferential surface 52a of the sliding portion 52. In other words, the protrusion 74 has an interference. Therefore, the inner circumferential surface 74a of the protrusion 74 is in liquid-tight contact with the outer circumferential surface 52a of the sliding portion 52, and the protrusion 74 supports the pin 32.

[0068] For example, the protrusion 74 supports the pin 32 so that the sliding portion 52 and the guide hole 62 are concentric. Hereinafter, for convenience, the state in which the sliding portion 52 and the guide hole 62 are concentric will be referred to as the normal state.

[0069] In a natural state, the diameter of the inner peripheral surface 71b of the ring portion 71 is larger than the diameter of the outer peripheral surface 52a of the sliding portion 52. Therefore, in a normal state, the inner peripheral surface 71b of the ring portion 71 is spaced apart from the pin 32. A gap G1 is provided between the inner peripheral surface 71b of the ring portion 71 and the outer peripheral surface 52a of the sliding portion 52.

[0070] In a natural state, the diameter of the inner peripheral surface 71b of the ring portion 71 is smaller than the diameter of the inner peripheral surface 62a of the guide hole 62. Therefore, in a normal state, the inner peripheral surface 71b of the ring portion 71 is closer to the pin 32 than the inner peripheral surface 62a of the guide hole 62.

[0071] In the normal state, the distance between the two side surfaces 71c, 71d of the ring portion 71 is shorter than the distance between the two side surfaces 65b, 65c of the mounting groove 65. Therefore, in the normal state, the side surface 65b of the mounting groove 65 is spaced apart from the ring portion 71 in the first direction D1. In addition, in the normal state, the side surface 65c of the mounting groove 65 is spaced apart from the ring portion 71 in the second direction D2. A gap G2 is provided between the side surfaces 65b, 65c and the ring portion 71. Note that one of the two side surfaces 65b, 65c may be in contact with the ring portion 71.

[0072] 6 is a cross-sectional view showing the mounting groove 65, a portion of the pin 32 that has moved, and the deformed ring portion 71 of the first embodiment. For example, when the vehicle 1 travels on a rough road surface, the movable part 23 may vibrate radially relative to the fixed part 24. In this case, the pin 32 moves radially from its normal position toward the inner circumferential surface 62a of the guide hole 62. Note that because the inner circumferential surface 74a of the protrusion 74 has a small diameter in its natural state, it continues to be in liquid-tight contact with the entire outer circumferential surface 52a of the sliding part 52 in the circumferential direction, even if the pin 32 moves.

[0073] As the pin 32 moves in the radial direction, it radially compresses the protrusion 74. The compressed protrusion 74 applies a reaction force to the pin 32 in the direction opposite to the movement direction of the pin 32. At this time, the pin 32 is spaced apart from the inner circumferential surface 71b of the ring portion 71 and does not receive the reaction force from the ring portion 71.

[0074] As the pin 32 moves further in the radial direction, it comes into contact with the inner circumferential surface 71b of the ring portion 71, compressing the ring portion 71 in the radial direction. The compressed ring portion 71 applies a reaction force to the pin 32. That is, the pin 32 receives reaction forces from both the protrusion 74 and the ring portion 71. When the pin 32 comes into contact with the inner circumferential surface 71b in this way, the spring constant of the boot 25 increases, and the reaction force that the boot 25 applies to the pin 32 also increases.

[0075] When the pin 32 abuts against the inner peripheral surface 71b of the ring portion 71, it is spaced apart from the inner peripheral surface 62a of the guide hole 62. That is, by compressing the protrusion 74, the pin 32 comes into contact with the inner peripheral surface 71b of the ring portion 71 before coming into contact with the inner peripheral surface 62a of the guide hole 62. Note that the pin 32 may be temporarily tilted and come into contact with the inner peripheral surface 62a of the guide hole 62.

[0076] When the protrusion 74 and the ring portion 71 are compressed in the radial direction, the ring portion 71 expands in the axial direction. When compressed by the pin 32, the ring portion 71 elastically deforms so as to come into contact with the side surfaces 65b and 65c of the mounting groove 65 before the pin 32 comes into contact with the inner circumferential surface 62a of the guide hole 62. In other words, when the pin 32 is spaced apart from the inner circumferential surface 62a of the guide hole 62, the ring portion 71 can come into contact with the side surfaces 65b and 65c of the mounting groove 65.

[0077] The side surfaces 65b and 65c contact the ring portion 71, thereby restricting the elastic deformation of the ring portion 71 so as to expand in the axial direction. By restricting the elastic deformation, the spring constant of the ring portion 71 in the radial direction increases, and the reaction force that the boot 25 applies to the pin 32 increases.

[0078] The spring constant of the boot 25 when the pin 32 contacts the inner circumferential surface 71b of the ring portion 71 is greater than the spring constant of the boot 25 in the normal state. Also, the spring constant of the boot 25 when the ring portion 71 contacts at least one of the side surfaces 65b, 65c of the mounting groove 65 is greater than the spring constant of the boot 25 in the normal state.

[0079] The reaction force of the boot 25 prevents the sliding portion 52 from colliding with the inner circumferential surface 62a of the guide hole 62, and pushes the pin 32 toward a position concentric with the guide hole 62. As a result, the boot 25 can suppress the occurrence of rattle caused by the pin 32 colliding with the inner circumferential surface 62a of the guide hole 62.

[0080] On the other hand, when a braking operation is performed or released, the movable part 23 moves in the first direction D1 or the second direction D2 relative to the fixed part 24. As shown in Fig. 5, in a normal state, the inner circumferential surface 71b of the ring part 71 is spaced apart from the outer circumferential surface 52a of the sliding part 52, and the ring part 71 is spaced apart from the side surfaces 65b, 65c of the mounting groove 65. Therefore, the contact area between the boot 25 and the pin 32 is small, and the reaction force that the boot 25 applies to the pin 32 is also small. In other words, the frictional force (sliding resistance) between the convex part 74 and the sliding part 52 is also small.

[0081] For example, when the braking operation is released, the sliding resistance is small, so the movable part 23 can move smoothly in the first direction D1. Therefore, the disc brake 10 can quickly separate the brake pad 21 from the disc rotor 11, thereby reducing the drag torque.

[0082] In the brake caliper 12 according to the first embodiment described above, the caliper body 31 holds the piston 22 so that it can move in a first direction D1 and a second direction D2 opposite to the first direction D1. The mount 61 holds the caliper body 31 so that it can move in the first direction D1 and the second direction D2. The pin 32 protrudes from the caliper body 31 in the first direction D1. The mount 61 is provided with a guide hole 62 that accommodates a portion of the pin 32, and has an inner circumferential surface 62a that faces the pin 32 at a position spaced from the pin 32. The boot 25 is elastically deformable and has a ring portion 71, an expandable portion 73, an inner circumferential surface 71b, and a protruding portion 74. The ring portion 71 is attached to the mount 61 and surrounds the pin 32. The expandable portion 73 is connected to the ring portion 71 to cover the pin 32 outside the guide hole 62 and expands and contracts in response to movement of the caliper body 31 relative to the mount 61. The inner peripheral surface 71b is provided on the ring portion 71 and faces the pin 32 at a position spaced apart from the pin 32 and closer to the pin 32 than the inner peripheral surface 62a. The protrusion 74 protrudes from the inner peripheral surface 71b and supports the pin 32.

[0083] As the pin 32 moves toward the inner circumferential surface 62a, it compresses the protrusion 74. As the pin 32 moves further, it contacts the inner circumferential surface 71b before contacting the inner circumferential surface 62a. That is, the pin 32 compresses not only the protrusion 74 but also the ring portion 71. By compressing both the protrusion 74 and the ring portion 71, the boot 25 applies a stronger reaction force to the pin 32, preventing the pin 32 from colliding with the inner circumferential surface 62a. This allows the brake caliper 12 to prevent rattle caused by the pin 32 colliding with the inner circumferential surface 62a. On the other hand, when the pin 32 is in a normal state, the protrusion 74 contacts the pin 32, but the inner circumferential surface 71b is spaced apart from the pin 32. That is, the contact area between the pin 32 and the boot 25 is small. Therefore, the boot 25 can reduce drag torque generated by sliding resistance between the boot 25 and the pin 32 when the pin 32 moves in the first direction D1 or the second direction D2. Therefore, the brake caliper 12 can suppress the occurrence of rattle and reduce drag torque. Furthermore, because the inner circumferential surface 71b and the protrusion 74 are provided on the boot 25, the brake caliper 12 can suppress increases in costs and manufacturing processes due to the addition of new parts.

[0084] The mount 61 has a side surface 65b that is spaced apart from the ring portion 71 in the first direction D1. The ring portion 71 is configured to be elastically deformed when compressed by the pin 32, causing the pin 32 to contact the side surface 65b before contacting the inner circumferential surface 62a.

[0085] The side surface 65b contacts the ring portion 71, thereby restricting the ring portion 71 from elastically deforming and expanding in the first direction D1. By restricting the ring portion 71's elastic deformation, it applies a stronger reaction force to the pin 32, preventing the pin 32 from colliding with the inner circumferential surface 62a. This allows the brake caliper 12 to prevent rattle from occurring due to the pin 32 colliding with the inner circumferential surface 62a. Meanwhile, when the ring portion 71 is spaced apart from the side surface 65b, the reaction force applied by the ring portion 71 to the pin 32 is small. This allows the boot 25 to reduce drag torque generated by sliding resistance between the boot 25 and the pin 32 when the pin 32 moves in the first direction D1 or the second direction D2. Therefore, the brake caliper 12 can prevent rattle from occurring and reduce drag torque.

[0086] The mount 61 has a side surface 65c that is spaced apart from the ring portion 71 in the second direction D2. The ring portion 71 is configured to be elastically deformed when compressed by the pin 32 so that the pin 32 contacts the side surface 65b and the side surface 65c before contacting the inner circumferential surface 62a.

[0087] The side surfaces 65b and 65c contact the ring portion 71, thereby restricting the ring portion 71 from elastically deforming and expanding. Therefore, the brake caliper 12 can suppress the occurrence of rattle and reduce drag torque. Furthermore, the side surfaces 65b and 65c can prevent the ring portion 71 from coming off the mount 61.

[0088] (Second embodiment) The second embodiment will be described below with reference to Fig. 7. In the following description of the embodiments, components having the same functions as components already described are given the same reference numerals as the components already described, and further description may be omitted. Furthermore, components given the same reference numerals do not necessarily have all the same functions and properties, and may have different functions and properties according to each embodiment.

[0089] Fig. 7 is a cross-sectional view showing a portion of a brake caliper 12 according to the second embodiment. As shown in Fig. 7, a boot 25 according to the second embodiment has a ring portion 201 and a protrusion 202 instead of the ring portion 71 and the protrusion 74. The ring portion 201 and the protrusion 202 are substantially the same as the ring portion 71 and the protrusion 74, except for the points described below.

[0090] The ring portion 201 and the protrusion 202 are made of different materials and are integrally formed by, for example, two-color molding. The material of the protrusion 202 is lower in hardness than the material of the ring portion 201. That is, the protrusion 202 is made of a material that is lower in hardness than the material of the inner circumferential surface 71b. Therefore, the spring constant of the protrusion 202 is lower than the spring constant of the ring portion 201. The hardness of the ring portion 201 and the protrusion 202 is, for example, a hardness measured with a durometer or an IRHD hardness tester.

[0091] The material of the ring portion 201 and the material of the protrusions 202 have similar viscosities and vulcanization rates, for example. In manufacturing the boot 25, the ring portion 201 and the protrusions 202 are molded so that their crosslinking timings coincide or are close to each other. This makes it possible to prevent the ring portion 201 and the protrusions 202 from peeling off from each other.

[0092] In the brake caliper 12 of the second embodiment described above, the protrusion 202 is made of a material that is lower in hardness than the material of the inner circumferential surface 71b. This reduces the reaction force that the protrusion 202 applies to the pin 32. Therefore, the boot 25 can reduce the drag torque that occurs due to the sliding resistance between the boot 25 and the pin 32 when the pin 32 moves in the first direction D1 or the second direction D2.

[0093] (Third embodiment) The third embodiment will be described below with reference to Fig. 8. Fig. 8 is a cross-sectional view showing a boot 25 and a pin 32 according to the third embodiment. As shown in Fig. 8, the boot 25 of the second embodiment has a protrusion 301 instead of the protrusion 74. The protrusion 301 is substantially the same as the protrusion 74, except for the points described below.

[0094] A plurality of grooves 305 are provided in the protrusion 301 instead of the groove 75. The plurality of grooves 305 are arranged around the central axis Axc of the pin 32. Each of the plurality of grooves 305 extends in the axial direction (first direction D1 and second direction D2), and is provided between both ends of the protrusion 74 in the axial direction.

[0095] In the brake caliper 12 of the third embodiment described above, the protrusion 301 is provided with a plurality of grooves 305. The plurality of grooves 305 are arranged around the pin 32. Each of the plurality of grooves 305 extends in the first direction D1. This allows the protrusion 301 to reduce drag torque that occurs due to sliding resistance between the protrusion 301 and the pin 32 when the pin 32 moves in the first direction D1 or the second direction D2.

[0096] In the above-described embodiments, the caliper body 31 is an example of a first member, and the mount 61 is an example of a second member. However, the mount 61 may be an example of a first member, and the caliper body 31 may be an example of a second member. In this case, the pin 32 protrudes from the mount 61, the caliper body 31 is provided with a guide hole 62, and the ring portion 71 is attached to the caliper body 31.

[0097] The brake caliper according to at least one embodiment described above may, for example, include a first member which is one of a caliper body that holds a piston movably in a first direction and a second direction opposite to the first direction, and a mount that holds the caliper body movably in the first direction and the second direction, a pin that protrudes from the first member in the first direction, and a first inner circumferential surface that is provided with a hole that accommodates a part of the pin and faces the pin at a position spaced from the pin, The caliper body includes a second member, which is the other of the caliper body and the mount; a ring portion attached to the second member and surrounding the pin; an expandable portion connected to the ring portion, covering the pin outside the hole, and expanding and contracting in response to movement of the caliper body relative to the mount; a second inner circumferential surface provided on the ring portion, spaced from the pin, facing the pin at a position closer to the pin than the first inner circumferential surface; and a protrusion protruding from the second inner circumferential surface and supporting the pin, the boot being elastically deformable. Thus, for example, the pin compresses the protrusion as it moves toward the first inner circumferential surface. As the pin moves further, it contacts the second inner circumferential surface before contacting the first inner circumferential surface. In other words, the pin compresses not only the protrusion but also the ring portion. By compressing both the protrusion and the ring portion, the boot applies a stronger reaction force to the pin, preventing the pin from colliding with the first inner circumferential surface. This allows the brake caliper to suppress rattle caused by the pin colliding with the first inner circumferential surface. Meanwhile, when the pin is positioned in its normal position, the protrusion contacts the pin, but the second inner circumferential surface is spaced apart from the pin. That is, the contact area between the pin and the boot is small. Therefore, the boot can reduce drag torque generated by sliding resistance between the boot and the pin when the pin moves in the first direction or the second direction. Therefore, the brake caliper can suppress rattle and reduce drag torque. Furthermore, because the second inner circumferential surface and the protrusion are provided on the boot, the brake caliper can suppress increases in costs and manufacturing processes due to the addition of new parts.

[0098] In the above-described brake caliper, as an example, the second member has a first side surface spaced from the ring portion in one of the first and second directions, and the ring portion is configured to elastically deform when compressed by the pin so that the pin contacts the first side surface before contacting the first inner circumferential surface. Therefore, as an example, the first side surface contacts the ring portion, thereby restricting the ring portion from elastically deforming in one direction and expanding. By restricting the elastic deformation of the ring portion, a stronger reaction force is applied to the pin, preventing the pin from colliding with the first inner circumferential surface. This allows the brake caliper to suppress rattle caused by the pin colliding with the first inner circumferential surface. Meanwhile, when the ring portion is spaced from the first side surface, the reaction force applied by the ring portion to the pin is small. Therefore, the boot can reduce drag torque generated by sliding resistance between the boot and the pin when the pin moves in the first or second direction. Therefore, the brake caliper can suppress rattle and reduce drag torque.

[0099] In the above-described brake caliper, as an example, the second member has a second side surface spaced from the ring portion in the other of the first and second directions, and the ring portion is configured to be compressed by the pin and elastically deform so as to contact the first and second side surfaces before the pin contacts the first inner circumferential surface. Therefore, as an example, the first and second side surfaces contact the ring portion, thereby restricting the ring portion from elastically deforming to expand. Therefore, the brake caliper can suppress rattle and reduce drag torque. Furthermore, the first and second side surfaces can prevent the ring portion from coming off the second member.

[0100] In the above brake caliper, for example, the protrusion is made of a material that is lower in hardness than the material of the second inner circumferential surface. Therefore, for example, the reaction force that the protrusion exerts on the pin is reduced. Therefore, the boot can reduce drag torque generated by sliding resistance between the boot and the pin when the pin moves in the first direction or the second direction.

[0101] In the brake caliper, for example, the protrusion has a plurality of grooves arranged around the pin and each extending in the first direction, and thus, for example, the protrusion can reduce drag torque generated by sliding resistance between the protrusion and the pin when the pin moves in the first direction or the second direction.

[0102] While the embodiments of the present invention have been described above, the above-described embodiments and modifications are merely examples and are not intended to limit the scope of the invention. The above-described embodiments and modifications can be implemented in various other forms, and various omissions, substitutions, combinations, and modifications can be made without departing from the spirit of the invention. Furthermore, the configurations and shapes of each embodiment and each modification can be partially interchanged. [Explanation of symbols]

[0103] 12...brake caliper, 22...piston, 25...boot, 31...caliper body, 32...pin, 61...mount, 62...guide hole, 62a...inner surface (first inner surface), 65b...side surface (first side surface), 65c...side surface (second side surface), 71, 201...ring portion, 71b...inner surface (second inner surface), 74, 202, 301...convex portion, 305...groove, D1...first direction, D2...second direction.

Claims

1. a first member that is one of a caliper body that holds a piston movably in a first direction and a second direction opposite to the first direction, and a mount that holds the caliper body movably in the first direction and the second direction; a pin protruding from the first member in the first direction; a second member having a hole for receiving a portion of the pin, a first inner circumferential surface facing the pin at a position spaced from the pin, and the second member being the other of the caliper body and the mount; an elastically deformable boot including: a ring portion attached to the second member and surrounding the pin; an expandable portion connected to the ring portion and covering the pin outside the hole and expanding and contracting in response to movement of the caliper body relative to the mount; a second inner circumferential surface provided on the ring portion, spaced apart from the pin and facing the pin at a position closer to the pin than the first inner circumferential surface; and a protrusion protruding from the second inner circumferential surface and supporting the pin; A brake caliper comprising:

2. the second member has a first side surface spaced from the ring portion in one of the first direction and the second direction; the annular portion is configured to be elastically deformed by being compressed by the pin so that the pin contacts the first side surface before contacting the first inner circumferential surface, The brake caliper of claim 1.

3. the second member has a second side surface spaced from the ring portion in the other of the first direction and the second direction, the annular portion is configured to be elastically deformed by being compressed by the pin so as to contact the first side surface and the second side surface before the pin contacts the first inner circumferential surface, 3. The brake caliper of claim 2.

4. the protrusion is made of a material having a lower hardness than the material of the second inner circumferential surface, 4. A brake caliper according to any one of claims 1 to 3.

5. The protrusion has a plurality of grooves arranged around the pin and each extending in the first direction. The brake caliper of claim 1.

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