Braking device

Abstract

To obtain a brake device capable of improving the durability, as an example.SOLUTION: A brake device according to an embodiment comprises: a rotary member; a linear motion member that can move in a first direction when the rotary member rotates in a first rotation direction, and can move in a second direction when the rotary member rotates in a second rotation direction; a piston that can press a brake pad in the first direction by being pressed in the first direction by the linear motion member; and a protrusion that protrudes from the brake pad, is accommodated in a recess provided on the piston, and has an inclined surface obliquely inclined with respect to the rotation axis. The piston that is rotated in the second rotation direction comes into contact, at a recess first end surface, with the inclined surface of the brake pad and presses the brake pad in the first direction, and when viewing the protrusion in the first direction, a projected area of the inclined surface is greater than a half of a projected area of the protrusion.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] Embodiments of the present invention relate to a braking device.

Background Art

[0002] Conventionally, a braking device is known that converts the rotation of a rotating member driven by an electric motor into the linear motion of a linear member, and presses a brake pad against a brake rotor via a piston by the linear member. The piston and the brake pad may be provided with convex and concave portions that fit together to limit the rotation of the piston. (Patent Document 1)

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the conventional configuration, if the rotation of the piston and the brake pad is restricted by the fitting of the convex and concave portions, a large load may be applied to the electric motor or the mechanism that transmits rotation between the electric motor and the rotating member. If the load is reduced, the durability of the braking device can be improved.

[0005] Therefore, the present invention has been made in view of the above, and provides a braking device capable of improving durability.

Means for Solving the Problems

[0006] A braking device according to an embodiment of the present invention includes, as an example, a rotating member having one of a male screw and a female screw that meshes with the male screw, and rotatable around a rotation axis; an electric motor that rotationally drives the rotating member; a linear member having the other of the male screw and the female screw, which is movable in a first direction along the rotation axis when the rotating member rotates in a first rotation direction around the rotation axis, and is movable in a second direction opposite to the first direction when the rotating member rotates in a second rotation direction opposite to the first direction; a brake pad spaced apart from the linear member in the first direction; and a component that restricts the linear member from rotating around the rotation axis. The brake pad is provided with a piston that is movable along the rotation axis relative to the linear motion member and is able to push the brake pad in the first direction when pushed in the first direction by the linear motion member, and a convex portion that protrudes from the brake pad and is housed in a recess provided in the piston and has an inclined surface that is tilted obliquely with respect to the rotation axis, wherein the piston, when rotated in the second rotation direction, contacts the inclined surface of the brake pad with the first end surface of the recess and pushes the brake pad in the first direction, and when the convex portion is viewed in the first direction, the projected area of ​​the inclined surface is greater than half the projected area of ​​the convex portion. The inclined surface has a first edge provided at the end of the inclined surface in the first rotation direction, and a second edge provided at the end of the inclined surface in the second rotation direction and parallel to the first edge, and extends flat between the first edge and the second edge. Therefore, for example, the inclination of the inclined surface with respect to the plane perpendicular to the axis of rotation is smaller compared to the case where the projected area of ​​the inclined surface is smaller than half the projected area of ​​the convex part. As a result, when the piston is rotated in the second rotational direction, the reaction force in the first rotational direction that the first end face of the concave part receives from the inclined surface is reduced. Consequently, for example, the load on the electric motor that drives the rotating member and the rotation transmission mechanism that transmits rotation between the electric motor and the rotating member is reduced, and the durability of the braking device may be improved. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic cross-sectional view showing a braking device according to the first embodiment. [Figure 2]Figure 2 is a cross-sectional view showing the piston and brake pad of the first embodiment along the line F2-F2 in Figure 1. [Figure 3] Figure 3 is a plan view showing the convex portion of the first embodiment. [Figure 4] Figure 4 is a cross-sectional view showing a part of the braking device of the first embodiment along the line F4-F4 in Figure 3. [Figure 5] Figure 5 is a plan view showing a portion of the piston and brake pad according to the second embodiment. [Modes for carrying out the invention]

[0008] (First Embodiment) The first embodiment will be described below with reference to Figures 1 to 4. Note that in this specification, the components of the embodiment and their descriptions may be described using multiple expressions. The components and their descriptions are examples and are not limited by the expressions used herein. Components may also be identified by names different from those used herein. Furthermore, components may also be described using expressions different from those used herein.

[0009] Figure 1 is a schematic cross-sectional view showing a braking device 10 according to a first embodiment. The braking device 10 is mounted on a vehicle 1 such as an automobile. Note that the braking device 10 is not limited to this example. As shown in Figure 1, the braking device 10 includes a caliper 11, a piston 12, a piston seal 13, a brake rotor 14, a brake pad 15, a rotary-to-linear motion conversion mechanism 16, a rotary transmission mechanism 17, an electric motor 18, and an ECU 19.

[0010] The braking device 10 can operate as a hydraulic brake and also as an electric brake. For example, the caliper 11, piston 12, piston seal 13, brake rotor 14, and brake pad 15 constitute a hydraulic brake. Alternatively, the caliper 11, piston 12, piston seal 13, brake rotor 14, brake pad 15, rotary-to-linear motion conversion mechanism 16, rotary transmission mechanism 17, and electric motor 18 constitute an electric brake. Note that the braking device 10 is not limited to these examples.

[0011] The electric brake is a so-called electric parking brake (EPB). In other words, the braking system 10 is configured so that the braking state due to the electric brake function is maintained when parked. The electric brake may also be activated when driving or when stopping.

[0012] A cylinder 21 is provided in the caliper 11. The cylinder 21 is a substantially cylindrical hole that opens into the outer surface of the caliper 11. Figure 1 shows the central axis Ax of the cylinder 21 by a dashed line. That is, the cylinder 21 extends along the central axis Ax. The central axis Ax is an example of a rotation axis. Note that the rotation axis may be different from the central axis of the cylinder 21.

[0013] In this specification, for convenience, axial, radial, and circumferential directions are defined. The axial direction is the direction along the central axis Ax and includes a first direction Dt1 and a second direction Dt2. The second direction Dt2 is the opposite direction to the first direction Dt1. The radial direction is the direction perpendicular to the central axis Ax. The circumferential direction is the direction around the central axis Ax.

[0014] Cylinder 21 is a bottomed hole open in a first direction Dt1. The piston 12 is housed in cylinder 21 so as to be movable in the axial direction. In cylinder 21, a hydraulic chamber R is provided between the piston 12 and the bottom surface 21a of cylinder 21 in a second direction Dt2.

[0015] The piston 12 has an outer peripheral surface 12a and an end surface 12b. The outer peripheral surface 12a is formed in a substantially cylindrical shape facing outward in the radial direction of the central axis Ax. The end surface 12b is provided at the end of the piston 12 in the first direction Dt1. The end surface 12b is formed substantially flat and faces the first direction Dt1.

[0016] A recess 12c is provided in the piston 12. The recess 12c is a bottomed hole opened in the second direction Dt2. The piston 12 forms part of the hydraulic chamber R. The recess 12c is formed, for example, in a substantially cylindrical shape. Note that the shape of the recess 12c is not limited to this example.

[0017] The outer peripheral surface 12a of the piston 12 and the inner peripheral surface 21b of the cylinder 21 face each other. The inner peripheral surface 21b is the inner surface of the caliper 11 formed in a substantially cylindrical shape facing inward in the radial direction of the central axis Ax.

[0018] A minute gap (clearance) is provided between the outer peripheral surface 12a of the piston 12 and the inner peripheral surface 21b of the cylinder 21. The piston 12 slides axially along the inner peripheral surface 21b in a state lubricated by the hydraulic oil existing in the gap.

[0019] The piston seal 13 is interposed between the outer peripheral surface 12a of the piston 12 and the inner peripheral surface 21b of the cylinder 21, and seals the gap between the outer peripheral surface 12a and the inner peripheral surface 21b. Thereby, the piston seal 13 suppresses the hydraulic oil from leaking from the hydraulic chamber R through the gap.

[0020] The piston seal 13 is attached to the inner peripheral surface 21b of the cylinder 21 and is restricted from moving with respect to the caliper 11. Note that the piston seal 13 may be attached to the outer peripheral surface 12a of the piston 12.

[0021] The brake rotor 14 rotates integrally with the wheel of the vehicle 1. The brake rotor 14 is separated from the cylinder 21 in the first direction Dt1. That is, the cylinder 21 opens toward the brake rotor 14.

[0022] The brake pad 15 is located between the piston 12 and the brake rotor 14. The brake pad 15 is supported, for example, by the caliper 11 so as to be axially movable. The brake pad 15 has a backing plate 31 and a friction material 32.

[0023] The backing plate 31 has a receiving surface 31a and a mounting surface 31b. The receiving surface 31a is formed to be substantially flat and faces the second direction Dt2. The end face 12b of the piston 12 and the receiving surface 31a of the backing plate 31 face each other. The mounting surface 31b is located on the opposite side of the receiving surface 31a. The mounting surface 31b faces the brake rotor 14. The friction material 32 is attached to the mounting surface 31b and is located between the brake rotor 14 and the backing plate 31.

[0024] When the hydraulic pressure in the hydraulic chamber R increases, the piston 12 is pushed in the first direction Dt1 by this hydraulic pressure and moves in the first direction Dt1. The piston 12 comes into contact with the receiving surface 31a of the backing plate 31 and presses against the backing plate 31, thereby pressing the friction material 32 against the brake rotor 14. As a result, the wheel of the vehicle 1 is braked, and a braking state by hydraulic brakes is obtained.

[0025] The piston seal 13 has a retract function in which, as the hydraulic pressure in the hydraulic chamber R decreases, the elastic force pulls the piston 12 in a second direction Dt2, separating the end face 12b of the piston 12 from the back plate 31. In other words, as the hydraulic pressure in the hydraulic chamber R decreases, the pressure of the piston 12 on the back plate 31 is released, and the pressure of the friction material 32 on the brake rotor 14 by the piston 12 is released. This results in a state of brake release by the hydraulic brake.

[0026] The rotary-to-linear motion conversion mechanism 16 includes a rotating member 41 and a linear motion member 42. Each of the rotating member 41 and the linear motion member 42 is at least partially housed in a cylinder 21. The rotating member 41 is supported by a caliper 11 so as to be rotatable about a central axis Ax. The linear motion member 42 is attached to the rotating member 41 so as to be linearly movable in the axial direction in response to the rotation of the rotating member 41.

[0027] The rotational transmission mechanism 17 is a reduction gear having multiple rotating elements, such as gears. The rotational transmission mechanism 17 is located outside the cylinder 21 and is covered, for example, by a cover. The rotational transmission mechanism 17 transmits the rotation of the output shaft of the electric motor 18 to the rotating member 41. The rotating member 41 rotates around its central axis Ax due to the torque input from the rotational transmission mechanism 17.

[0028] The rotating member 41 has a coupling portion 51, a flange 52, and a shaft 53. The coupling portion 51 is connected, for example, to the output gear of the rotation transmission mechanism 17 through a hole opening in the bottom surface 21a of the cylinder 21, and rotates together with the output gear.

[0029] The flange 52 and shaft 53 are located inside the cylinder 21. The flange 52 is located between the coupling portion 51 and the shaft 53 and is formed in a substantially disc shape that protrudes radially from the coupling portion 51 and the shaft 53.

[0030] The shaft 53 protrudes from the flange 52 in a first direction Dt1. The shaft 53 is formed in a substantially cylindrical shape that extends axially along the central axis Ax. In this embodiment, the central axis Ax is also the central axis of the flange 52 and the shaft 53.

[0031] A thrust bearing 55 is provided between the flange 52 and the bottom surface 21a of the cylinder 21. The caliper 11 supports the rotating member 41 in the axial direction via the thrust bearing 55.

[0032] The shaft 53 has an outer circumferential surface 53a. The outer circumferential surface 53a is a substantially cylindrical curved surface that extends axially and faces radially outward. A male screw 57 is provided on the outer circumferential surface 53a.

[0033] The linear motion member 42 extends in the axial direction and is formed in a substantially cylindrical shape surrounding the central axis Ax. The linear motion member 42 has an inner circumferential surface 42a and an outer circumferential surface 42b. The inner circumferential surface 42a is a substantially cylindrical curved surface that extends in the axial direction and faces inward in the radial direction. The outer circumferential surface 42b is located on the opposite side of the inner circumferential surface 42a. The outer circumferential surface 42b is a substantially cylindrical curved surface that extends in the axial direction and faces outward in the radial direction.

[0034] An internal thread 58 is provided on the inner circumferential surface 42a. The internal thread 58 engages with the external thread 57 of the rotating member 41. Alternatively, the internal thread may be provided on the rotating member 41 and the external thread on the linear motion member 42.

[0035] A portion of the rotary-to-linear motion conversion mechanism 16 is housed inside the recess 12c of the piston 12. A portion of the shaft 53 of the rotating member 41 is located inside the recess 12c of the piston 12. The linear motion member 42 is also provided to be axially movable inside the recess 12c.

[0036] A guide groove 12d extending in the axial direction is provided in the recess 12c of the piston 12. For example, a projection 42c protruding from the outer circumferential surface 42b of the linear motion member 42 is fitted into the guide groove 12d. This restricts the piston 12 from rotating around the central axis Ax relative to the linear motion member 42, while allowing it to move axially relative to the linear motion member 42. Note that the piston 12 and the linear motion member 42 may be able to rotate slightly relative to each other around the central axis Ax.

[0037] As described above, the male screw 57 of the rotating member 41 and the female screw 58 of the linear motion member 42 engage with each other, and the relative rotation between the piston 12 and the linear motion member 42 is restricted. As a result, the linear motion member 42 can move linearly in the axial direction in accordance with the rotation of the rotating member 41. In other words, the linear motion member 42 can move substantially parallel in the axial direction.

[0038] The electric motor 18 is driven by drive power based on a control signal. The electric motor 18 rotates its output shaft, thereby rotating the rotating member 41 around the central axis Ax via the rotation transmission mechanism 17.

[0039] The brake pad 15 is spaced apart from the linear motion member 42 in a first direction Dt1, and the piston 12 is positioned between the brake pad 15 and the linear motion member 42. The linear motion member 42 can push the brake pad 15 via the piston 12 in accordance with the rotation of the rotating member 41.

[0040] Figure 2 is a cross-sectional view showing the piston 12 and brake pad 15 of the first embodiment along the line F2-F2 in Figure 1. The rotating member 41 shown in Figure 1 is rotatable in a first rotation direction Dr1 and a second rotation direction Dr2 shown in Figure 2. The first rotation direction Dr1 and the second rotation direction Dr2 are included in the circumferential direction. The second rotation direction Dr2 is the opposite direction to the first rotation direction Dr1.

[0041] When the output shaft of the electric motor 18 rotates in one direction, the rotating member 41 rotates in the first rotational direction Dr1. When the rotating member 41 rotates in the first rotational direction Dr1, the linear motion member 42 moves in a straight line in the first direction Dt1.

[0042] The linear motion member 42, which moves in the first direction Dt1, pushes the piston 12 in the first direction Dt1. As the piston 12 is pushed by the linear motion member 42, it moves in the first direction Dt1 and comes into contact with the receiving surface 31a of the backing plate 31 of the brake pad 15.

[0043] The piston 12 is pushed in the first direction Dt1 by the linear motion member 42, thereby pushing the backing plate 31 of the brake pad 15 in the first direction Dt1. As a result, the piston 12 presses the friction material 32 against the brake rotor 14 via the backing plate 31. Thus, a braking state is obtained by the electric brake function, in which the wheel of the vehicle 1, which rotates integrally with the brake rotor 14, is braked.

[0044] When the output shaft of the electric motor 18 rotates in the opposite direction, the rotating member 41 rotates in the second rotation direction Dr2. When the rotating member 41 rotates in the second rotation direction Dr2, the linear motion member 42 moves in a straight line in the second direction Dt2, away from the piston 12. The movement of the linear motion member 42 in the second direction Dt2 reduces the pressing force of the piston 12 against the back plate 31, and the pressing of the friction material 32 against the brake rotor 14 by the piston 12 is released. As a result, a state of release of braking by the electric brake function (non-braking state) is obtained.

[0045] In this embodiment, the ECU 19 shown in Figure 1 controls the electric motor 18. The ECU 19 may be partially composed of hardware such as a CPU and controller that execute software, or it may be entirely composed of hardware. Note that the electric motor 18 is not limited to the ECU 19; for example, it may be controlled by a dedicated controller of the braking device 10.

[0046] For example, when the ECU 19 receives an instruction signal from the electric brake function's operating switch (SW) to transition to a braking state, it controls the electric motor 18 so that the rotating member 41 rotates in a first rotational direction Dr1. On the other hand, when the ECU 19 receives an instruction signal from the operating switch to release the braking state, it controls the electric motor 18 so that the rotating member 41 rotates in a second rotational direction Dr2.

[0047] As shown in Figure 2, the braking device 10 further includes an engagement structure 60. The engagement structure 60 has recesses 61, 62, and 63 provided on the piston 12 and a protrusion 65 that extends from the brake pad 15.

[0048] The recesses 61, 62, and 63 are recessed in a second direction Dt2 from the end face 12b of the piston 12. The recesses 61 and 62 are spaced radially outward from the central axis Ax and open to the outer circumferential surface 12a and end face 12b of the piston 12. The recess 63 is provided along the central axis Ax and communicates with the recesses 61 and 62. The piston 12 may also be provided with only the recess 61.

[0049] The piston 12 has a first recessed end surface 61a that contacts the protrusion 65 of the backing plate 31 when rotated in the second rotation direction Dr2, and a second recessed end surface 61b that contacts the protrusion 65 of the backing plate 31 when rotated in the first rotation direction Dr1. In this embodiment, the first recessed end surface 61a and the second recessed end surface 61b are planes substantially parallel to the central axis Ax. Note that the first recessed end surface 61a and the second recessed end surface 61b are not limited to this example.

[0050] The first recessed end face 61a is formed to be substantially flat and faces the second rotation direction Dr2. The second recessed end face 61b is formed to be substantially flat and faces the first rotation direction Dr1. In the projection plane viewed from the piston 12 in the second direction Dt2, the first recessed end face 61a and the second recessed end face 61b each extend in a straight line. In this embodiment, in the projection plane, the extension of the first recessed end face 61a and the extension of the second recessed end face 61b intersect at the central axis Ax. Note that the first recessed end face 61a and the second recessed end face 61b are not limited to this example.

[0051] The protrusion 65 is positioned radially outward from the central axis Ax and protrudes in a second direction Dt2 from the receiving surface 31a of the backing plate 31. The protrusion 65 is at least partially housed in the recess 61. That is, in the circumferential direction, the protrusion 65 is located between the first end face 61a and the second end face 61b of the recess 61. In the circumferential direction, the length of the protrusion 65 is shorter than the distance between the first end face 61a and the second end face 61b of the recess 61.

[0052] Figure 3 is a plan view showing the protrusion 65 of the first embodiment. As shown in Figure 3, the protrusion 65 is formed in a block shape having a substantially trapezoidal cross-section that tapers toward the central axis Ax. Note that the protrusion 65 is not limited to this example. The protrusion 65 of this embodiment has an end face 71, an inner surface 72, an outer surface 73, a regulating surface 74, and an inclined surface 75.

[0053] The end face 71 is provided at the end of the protrusion 65 in the second direction Dt2. The end face 71 is formed to be substantially flat and faces the second direction Dt2. That is, the end face 71 is a plane substantially perpendicular to the axial direction.

[0054] The length of the axial projection 65 is shorter than the depth of the axial recess 61. Therefore, the entire projection 65 can be accommodated in the recess 61. The length of the axial projection 65 is the distance between the receiving surface 31a and the end surface 71 in the axial direction.

[0055] The inner surface 72 is formed to be substantially flat and faces radially inward. In other words, the inner surface 72 faces the central axis Ax. The outer surface 73 is located on the opposite side of the inner surface 72. The outer surface 73 is formed to be substantially flat and faces radially outward.

[0056] The restricting surface 74 is the end of the convex portion 65, located on the side that contacts the second end surface 61b of the recess when the piston 12 is rotated in the first rotation direction Dr1. The restricting surface 74 is a plane substantially parallel to the central axis Ax. Note that the restricting surface 74 is not limited to this example. The restricting surface 74 is formed to be substantially flat. The restricting surface 74 faces the second end surface 61b of the recess when the second end surface 61b of the recess contacts the convex portion 65. Also, when the second end surface 61b of the recess contacts the convex portion 65, the restricting surface 74 faces approximately the opposite direction from the direction in which the second end surface 61b of the recess faces. However, in this embodiment, the direction in which the restricting surface 74 faces is slightly different from the opposite direction from the direction in which the second end surface 61b of the recess faces.

[0057] The restricting surface 74 is connected to the end of the inner surface 72 closest to the second recessed end surface 61b via a corner 76. Furthermore, the restricting surface 74 is connected to the end of the outer surface 73 closest to the second recessed end surface 61b via a corner 77. The corners 76 and 77 are roughly semi-cylindrical curved surfaces. Note that the corners 76 and 77 are not limited to this example.

[0058] Figure 4 is a cross-sectional view showing a part of the braking device 10 of the first embodiment along the line F4-F4 in Figure 3. As shown in Figure 4, the inclined surface 75 is tilted obliquely with respect to the central axis Ax. In other words, the inclined surface 75 is neither perpendicular to the central axis Ax nor parallel to the central axis Ax.

[0059] The inclined surface 75 has a first edge 81 and a second edge 82. The first edge 81 is located at the end of the inclined surface 75 in the first rotation direction Dr1. In other words, the first edge 81 is located at the end of the inclined surface 75 closer to the first recessed end face 61a. The second edge 82 is located at the end of the inclined surface 75 in the second rotation direction Dr2. In other words, the second edge 82 is located at the end of the inclined surface 75 closer to the second recessed end face 61b. Therefore, the second edge 82 is closer to the regulating surface 74 than the first edge 81.

[0060] As shown in Figure 3, one end 81a of the first edge 81 is connected via a corner 85 to the end of the inner surface 72 closer to the first recessed end surface 61a. Furthermore, the other end 81b of the first edge 81 is connected via a corner 86 to the end of the outer surface 73 closer to the first recessed end surface 61a. The corners 85 and 86 are approximately semi-cylindrical curved surfaces. Note that the corners 85 and 86 are not limited to this example.

[0061] The first edge 81 is closer to the receiving surface 31a than the second edge 82. The second edge 82 is connected to the end face 71. In other words, the second edge 82 forms the boundary between the end face 71 and the inclined surface 75. With the inclined surface 75 provided, the convex portion 65 tapers toward the second direction Dt2.

[0062] In this embodiment, the first edge 81 and the second edge 82 each extend in a straight line. The first edge 81 and the second edge 82 are substantially parallel to each other. The inclined surface 75 extends flat between the first edge 81 and the second edge 82.

[0063] As shown in Figure 2, in the projection plane where the convex portion 65 is viewed in the first direction Dt1, the first edge 81 and the regulating surface 74 each extend in a straight line. In this projection plane, the extension of the first edge 81 and the extension of the regulating surface 74 intersect in region Ab between the convex portion 65 and the central axis Ax. Region Ab is, for example, the region connecting the central axis Ax, the end of the convex portion 65 in the first rotation direction Dr1, and the end of the convex portion 65 in the second rotation direction Dr2.

[0064] In this embodiment, in the projection plane where the convex portion 65 is viewed in the first direction Dt1, the intersection point of the extension line of the first edge 81 and the extension line of the regulating surface 74 lies on the line connecting the center of the convex portion 65 in the circumferential direction and the central axis Ax. Note that the intersection point of the extension line of the first edge 81 and the extension line of the regulating surface 74 is not limited to this example.

[0065] On the other hand, in the projection plane where the convex portion 65 is viewed in the first direction Dt1, the extension line of the first recessed end face 61a and the extension line of the second recessed end face 61b intersect at a position closer to the central axis Ax than the intersection point of the extension line of the first edge 81 and the extension line of the regulating surface 74. In this embodiment, as described above, the extension line of the first recessed end face 61a and the extension line of the second recessed end face 61b intersect at the central axis Ax. However, the extension line of the first recessed end face 61a and the extension line of the second recessed end face 61b may intersect at other positions.

[0066] The protrusion 65 is formed on the back plate 31 by, for example, press working. Therefore, a recess is provided on the mounting surface 31b of the back plate 31 at a position opposite to the protrusion 65. Note that the protrusion 65 is not limited to this example and may be formed, for example, by attaching a different part to the back plate 31.

[0067] When the rotating member 41 rotates and the linear member 42 moves in the axial direction, friction between, for example, the male screw 57 and the female screw 58 may cause the linear member 42 to rotate together with the rotating member 41 around the central axis Ax. As the linear member 42 rotates, the projection 42c and the guide groove 12d engage with each other, causing the piston 12 to rotate around the central axis Ax. In other words, co-rotation occurs between the piston 12 and the rotating member 41 and the linear member 42.

[0068] When the piston 12 is rotated in the first rotational direction Dr1, the restricting surface 74 of the protrusion 65 comes into contact with the second end surface 61b of the recess. The brake pad 15 is supported by the caliper 11 so as to restrict the rotation of the brake pad 15. Therefore, the protrusion 65 provided on the brake pad 15 restricts the piston 12 from rotating further in the first rotational direction Dr1. That is, when the piston 12 is rotated in the first rotational direction Dr1, the protrusion 65 comes into contact with the second end surface 61b of the recess, thereby restricting the piston 12 from rotating in the first rotational direction Dr1. In this way, the engagement structure 60 restricts the accompanying rotation of the piston 12 in the first rotational direction Dr1.

[0069] Both the second recessed end face 61b and the regulating surface 74 are planes substantially parallel to the central axis Ax. Therefore, the second recessed end face 61b and the regulating surface 74 can suppress changes in the force (braking force) that the piston 12 exerts on the brake pad 15 against the brake rotor 14 while the second recessed end face 61b is pressing against the regulating surface 74.

[0070] As shown in Figure 4, when the piston 12 rotates in the second rotational direction Dr2, the inclined surface 75 of the convex portion 65 comes into contact with the first end surface 61a of the concave portion. The first end surface 61a of the concave portion of the piston 12, driven in the second rotational direction Dr2, pushes the inclined surface 75 in the second rotational direction Dr2.

[0071] The friction between the male screw 57 and the female screw 58 generates a relatively small force that drives the piston 12 in the second rotational direction Dr2. Therefore, the reaction force acting from the inclined surface 75 to the first end face 61a of the recess limits the piston 12 from rotating in the second rotational direction Dr2. In other words, the protrusion 65 limits the piston 12 from rotating further in the second rotational direction Dr2.

[0072] On the other hand, for example, to replace the brake pads 15, the rotating member 41 may be rotated in the second rotational direction Dr2, and the linear motion member 42 may be moved to its maximum extent in the second direction Dt2. When the linear motion member 42 is moved to its maximum extent in the second direction Dt2, it comes into contact with the flange 52 of the rotating member 41. In this case, the male screw 57 and the female screw 58 are fully tightened, and the rotating member 41 and the linear motion member 42 rotate together (locked state). In the locked state, the force with which the rotating member 41 drives the linear motion member 42 and the piston 12 in the second rotational direction Dr2 becomes greater.

[0073] When the piston 12 is driven in the second rotational direction Dr2, the first end face 61a of the recess pushes the inclined surface 75 in the second rotational direction Dr2. Because the inclined surface 75 is inclined as described above, the component of the force that the piston 12 exerts on the inclined surface 75 pushes the inclined surface 75 in the first direction Dt1. That is, the piston 12, rotated in the second rotational direction Dr2, contacts the inclined surface 75 with the first end face 61a of the recess and pushes the brake pad 15 in the first direction Dt1. As a result, the brake pad 15 and the piston 12 move apart from each other.

[0074] The energy that the piston 12 exerts on the inclined surface 75 is consumed by the movement of the brake pad 15 and the piston 12. Therefore, in the locked state, the load on the electric motor 18 and the rotation transmission mechanism 17 is reduced. When the brake pad 15 and the piston 12 move apart from each other and the convex portion 65 disengages from the concave portion 61, the load on the electric motor 18 and the rotation transmission mechanism 17 is further reduced.

[0075] As shown in Figure 3, when the convex portion 65 is viewed in the first direction Dt1, the projected area of ​​the inclined surface 75 is greater than half the projected area of ​​the convex portion 65. In this embodiment, one end 82a of the second edge 82 is connected to the corner portion 76. The end 82a of the second edge 82 may also be connected to the inner surface 72. In this way, the end 82a of the second edge 82 is closer to the first edge 81 than to the regulating surface 74. That is, the regulating surface 74 is not damaged by the provision of the inclined surface 75, and the durability of the convex portion 65 when the regulating surface 74 abuts against the second end surface 61b of the recess is improved.

[0076] In the braking device 10 according to the first embodiment described above, the protrusion 65 protrudes from the brake pad 15 and is housed in a recess 61 provided on the piston 12. The protrusion 65 has an inclined surface 75 that is tilted obliquely with respect to the central axis Ax. The piston 12, rotated in the second rotational direction Dr2, contacts the inclined surface 75 with the first end surface 61a of the recess and pushes the brake pad 15 in the first direction Dt1. When the protrusion 65 is viewed in the first direction Dt1, the projected area of ​​the inclined surface 75 is greater than half the projected area of ​​the protrusion 65. For example, in order to replace the brake pad 15, the rotating member 41 may be rotated in the second rotational direction Dr2 until the linear member 42 moves to its maximum extent in the second direction Dt2. When the linear motion member 42 moves to its maximum extent in the second direction Dt2, the linear motion member 42 and the rotating member 41 rotate together (locked state), and the rotating member 41, the linear motion member 42, and the piston 12 can rotate together in the second rotation direction Dr2. In the braking device 10 described above, the inclination of the inclined surface 75 with respect to the plane perpendicular to the central axis Ax is smaller compared to the case where the projected area of ​​the inclined surface 75 is smaller than half the projected area of ​​the convex portion 65. Therefore, when the piston 12 is rotated in the second rotation direction Dr2, the reaction force in the first rotation direction Dr1 that the recessed first end face 61a receives from the inclined surface 75 is reduced. Consequently, for example, the load on the electric motor 18 that drives the rotating member 41 and the rotation transmission mechanism 17 that transmits rotation between the electric motor 18 and the rotating member 41 is reduced, and the durability of the braking device 10 can be improved. Furthermore, the inclined surface 75 of the braking device 10 described above allows for a longer time from when the piston 12 begins to rotate in the second rotation direction Dr2 until the first end surface 61a of the recess contacts the inclined surface 75, compared to the case where the projected area of ​​the inclined surface 75 is less than half the projected area of ​​the convex portion 65. Therefore, for example, the rotation of the piston 12 can be stopped before the first end surface 61a of the recess contacts the inclined surface 75, thereby reducing the frequency with which the electric motor 18 and the rotation transmission mechanism 17 are subjected to load, and potentially improving the durability of the braking device 10.

[0077] The inclined surface 75 has a first edge 81 and a second edge 82. The first edge 81 is provided at the end of the inclined surface 75 in the first rotation direction Dr1. The second edge 82 is provided at the end of the inclined surface 75 in the second rotation direction Dr2 and is parallel to the first edge 81. The inclined surface 75 extends flat between the first edge 81 and the second edge 82. This increases the distance over which the first end face 61a of the recess presses against the inclined surface 75 when the piston 12 is rotated in the second rotation direction Dr2. Also, when the piston 12 is rotated in the second rotation direction Dr2, fluctuations in the reaction force in the first rotation direction Dr1 that the first end face 61a of the recess receives from the inclined surface 75 are suppressed. Therefore, the load on the electric motor 18 and the rotation transmission mechanism 17 is reduced, and the durability of the braking device 10 can be improved.

[0078] The first recessed end face 61a and the second recessed end face 61b, which contacts the convex portion 65 when the piston 12 is rotated in the first rotational direction Dr1, are each provided parallel to the central axis Ax. If the first recessed end face 61a is tilted at an angle with respect to the central axis Ax, the contact area between the piston 12 and the brake pad 15 will decrease compared to this embodiment in which the first recessed end face 61a is parallel to the central axis Ax. In this embodiment, because the first recessed end face 61a is parallel to the central axis Ax, the braking device 10 can reduce the change in surface pressure between the piston 12 and the brake pad 15 by designing it to have an inclined surface 75 that pushes the brake pad 15 in the first direction Dt1 when the piston 12 is rotated in the second rotational direction Dr2. Therefore, the braking device 10 can eliminate concerns about squeal (noise).

[0079] The protrusion 65 has a restricting surface 74 that contacts the second end face 61b of the recess when the piston 12 is rotated in the first rotation direction Dr1, thereby restricting the piston 12 from rotating in the first rotation direction Dr1. In a projection plane viewed from the first direction Dt1, the first edge 81 and the restricting surface 74 each extend in a straight line. In this projection plane, the extension of the first edge 81 and the extension of the restricting surface 74 intersect in region Ab between the protrusion 65 and the central axis Ax. On the other hand, in this projection plane, the extension of the first end face 61a of the recess and the extension of the second end face 61b of the recess intersect at a position closer to the central axis Ax than the intersection of the extension of the first edge 81 and the extension of the restricting surface 74. As a result, the first end face 61a of the recess and the inclined surface 75 can come into contact at a position further from the central axis Ax. Therefore, when the piston 12 is rotated in the second rotational direction Dr2, the load generated between the recessed first end face 61a and the inclined surface 75 is reduced, which can improve the durability of the braking device 10.

[0080] (Second embodiment) A second embodiment will be described below with reference to Figure 5. In the following description of the embodiments, components having the same function as those already described will be denoted by the same reference numerals as those previously described, and their description may be omitted. Furthermore, multiple components denoted by the same reference numerals do not necessarily share all functions and properties, and may have different functions and properties depending on the embodiment.

[0081] Figure 5 is a plan view showing a portion of the piston 12 and brake pad 15 according to the second embodiment. Note that Figure 5 shows a cross-section of the piston 12. As shown in Figure 5, the protrusion 65 of the second embodiment has an inclined surface 90 instead of an inclined surface 75. The inclined surface 90 is substantially the same as the inclined surface 75 of the first embodiment, except as described below.

[0082] The inclined surface 90 has a second edge 92 instead of the second edge 82. The second edge 92 is substantially the same as the second edge 82 of the first embodiment, except as described below. The second edge 92 extends in a straight line. However, unlike the second edge 82 of the first embodiment, the second edge 92 of the second embodiment is not parallel to the first edge 81.

[0083] As shown in Figure 5, in the projection plane where the convex portion 65 is viewed in the first direction Dt1, the extension of the first edge 81 and the extension of the second edge 92 intersect in region Ab between the convex portion 65 and the central axis Ax. Alternatively, the extension of the first edge 81 and the extension of the second edge 92 may intersect at the central axis Ax.

[0084] In this embodiment, in the projection plane where the convex portion 65 is viewed in the first direction Dt1, the intersection point of the extension line of the first edge 81 and the extension line of the second edge 92 lies on the line connecting the center of the convex portion 65 in the circumferential direction and the central axis Ax. Note that the intersection point of the extension line of the extension line of the first edge 81 and the extension line of the second edge 92 is not limited to this example.

[0085] In the braking device 10 of the second embodiment described above, the inclined surface 90 has a first edge 81 and a second edge 92. The first edge 81 is provided at the end of the inclined surface 90 in the first rotation direction Dr1 and extends linearly. The second edge 92 is provided at the end of the inclined surface 90 in the second rotation direction Dr2 and extends linearly. In the projection plane viewed from the first direction Dt1 with respect to the convex portion 65, the extension of the first edge 81 and the extension of the second edge 92 intersect at the central axis Ax, or in the region Ab between the convex portion 65 and the central axis Ax. That is, the first edge 81 and the second edge 92 extend radially from a point near the central axis Ax. As a result, when the piston 12 is rotated in the second rotation direction Dr2, the first end face 61a of the recess and the inclined surface 90 can always be in line contact. Therefore, the surface pressure between the first recessed end face 61a and the inclined surface 90 is reduced, and damage to the brake pad 15 and piston 12 is suppressed.

[0086] In the embodiments described above, the first edge 81 and the second edge 82, 92 of the inclined surfaces 75, 90 extend in a straight line. However, the first and second edges of the inclined surfaces are not limited to these examples and may extend in a curved shape.

[0087] A braking device according to at least one embodiment described above includes, as an example, a rotating member having one of a male screw and a female screw that meshes with the male screw, and rotatable around a rotation axis, an electric motor that rotationally drives the rotating member, a linear member having the other of the male screw and the female screw, which is movable in a first direction along the rotation axis when the rotating member rotates in a first rotation direction around the rotation axis, and is movable in a second direction opposite to the first direction when the rotating member rotates in a second rotation direction opposite to the first direction, a brake pad spaced apart from the linear member in the first direction, and a motor that rotates relative to the linear member around the rotation axis The brake pad is supported by a piston that is restricted in its movement and movable along the rotation axis relative to the linear member, and is able to push the brake pad in the first direction when pushed in the first direction by the linear member, and a convex portion that protrudes from the brake pad and is housed in a recess provided in the piston, and has an inclined surface that is tilted obliquely with respect to the rotation axis, wherein when the piston is rotated in the second rotation direction, the first end face of the recess contacts the inclined surface of the brake pad and pushes the brake pad in the first direction, and when the convex portion is viewed in the first direction, the projected area of ​​the inclined surface is greater than half the projected area of ​​the convex portion. For example, in order to replace the brake pad, the rotating member may be rotated in the second rotation direction until the linear member moves to its maximum extent in the second direction. When the linear member moves to its maximum extent in the second direction, the linear member and the rotating member rotate together (locked state), and the rotating member, the linear member, and the piston can rotate together in the second rotation direction. In the braking device described above, the inclination of the inclined surface with respect to the plane perpendicular to the axis of rotation is smaller compared to the case where the projected area of ​​the inclined surface is less than half the projected area of ​​the convex part. Therefore, when the piston is driven in the second rotational direction, the reaction force in the first rotational direction that the first end face of the recess receives from the inclined surface is reduced. Consequently, the load on, for example, the electric motor that drives the rotating member and the rotation transmission mechanism that transmits rotation between the electric motor and the rotating member is reduced, and the durability of the braking device may be improved.Furthermore, the inclined surface of the braking device described above allows for a longer time between the piston starting to rotate in the second rotational direction and the first end surface of the recess contacting the inclined surface, compared to the case where the projected area of ​​the inclined surface is less than half the projected area of ​​the convex portion. Therefore, for example, the rotation of the piston may stop before the first end surface of the recess contacts the inclined surface, thereby reducing the frequency of load on the electric motor and drive mechanism, and potentially improving the durability of the braking device.

[0088] In the above braking device, for example, the inclined surface has a first edge provided at the end of the inclined surface in the first rotation direction, and a second edge provided at the end of the inclined surface in the second rotation direction and parallel to the first edge, and extends flat between the first edge and the second edge. Therefore, for example, when the piston is driven in the second rotation direction, the distance over which the first end face of the recess presses against the inclined surface is increased. Also, when the piston is driven in the second rotation direction, fluctuations in the reaction force in the first rotation direction received by the first end face of the recess from the inclined surface are suppressed. Consequently, the load on the electric motor and drive mechanism is reduced, and the durability of the braking device may be improved.

[0089] In the above-described braking device, for example, the first recessed end face and the second recessed end face, which contacts the protrusion when the piston is rotated in the first rotational direction, are each provided parallel to the axis of rotation. For example, if the first recessed end face and the second recessed end face were inclined at an angle with respect to the axis of rotation, the contact area between the piston and the brake pad would decrease compared to the case where the first recessed end face and the second recessed end face are parallel to the axis of rotation. In the above-described braking device, since the first recessed end face and the second recessed end face are parallel to the axis of rotation, the change in surface pressure between the piston and the brake pad can be reduced by designing the device to have an inclined surface that pushes the brake pad in the first direction when the piston is driven in the second rotational direction. Therefore, the braking device can eliminate concerns about squeal (noise).

[0090] In the above braking device, as an example, the protrusion has a restricting surface that contacts the second end surface of the recess when the piston is rotated in the first rotation direction, thereby restricting the piston from rotating in the first rotation direction. In the projection plane viewed from the first direction, the first edge and the restricting surface each extend in a straight line, the extension of the first edge and the extension of the restricting surface intersect in the region between the protrusion and the axis of rotation, and the extension of the first end surface of the recess and the extension of the second end surface of the recess intersect at a position closer to the axis of rotation than the intersection of the extension of the first edge and the extension of the restricting surface. Therefore, as an example, the first end surface of the recess and the inclined surface can come into contact with each other at a position further from the axis of rotation. Consequently, when the piston is rotated in the second rotation direction, the load generated between the first end surface of the recess and the inclined surface is reduced, and the durability of the braking device can be improved.

[0091] In the above braking device, as an example, the inclined surface has a first edge provided at the end of the inclined surface in the first rotation direction and extending linearly, and a second edge provided at the end of the inclined surface in the second rotation direction and extending linearly. In the projection plane viewed from the convex portion in the first direction, the extensions of the first edge and the second edge intersect at the axis of rotation or in the region between the convex portion and the axis of rotation. Therefore, as an example, the first edge and the second edge extend radially from a point near the axis of rotation. As a result, when the piston is driven in the second rotation direction, the first end face of the recess and the inclined surface can always be in line contact. Consequently, the surface pressure between the first end face of the recess and the inclined surface is reduced, and damage to the brake pad and piston is suppressed.

[0092] In the above description, suppression is defined, for example, as preventing the occurrence of an event, action, or effect, or reducing the degree of an event, action, or effect. Also in the above description, restriction is defined, for example, as preventing movement or rotation, or allowing movement or rotation within a predetermined range while preventing movement or rotation beyond that predetermined range.

[0093] Although embodiments of the present invention have been illustrated above, these embodiments and modifications are merely examples and are not intended to limit the scope of the invention. The above embodiments and modifications can be implemented in various other forms, and various omissions, substitutions, combinations, and changes can be made without departing from the spirit of the invention. Furthermore, the configurations and shapes of each embodiment and modification can be partially replaced. [Explanation of symbols]

[0094] 10... Braking device, 12... Piston, 15... Brake pad, 41... Rotating member, 42... Linear motion member, 57... Male screw, 58... Female screw, 61... Recess, 61a... First end face of recess, 61b... Second end face of recess, 65... Protrusion, 74... Restricting surface, 75, 90... Inclined surface, 81... First edge, 82, 92... Second edge, Ax... Central axis (rotation axis), Dt1... First direction, Dt2... Second direction, Dr1... First rotation direction, Dr2... Second rotation direction, Ab... Region.

Claims

1. A rotating member is provided with either a male screw or a female screw that meshes with the male screw, and is rotatable around a rotation axis. An electric motor that rotates the aforementioned rotating member, A linear motion member is provided with the other of the male and female threads, and is movable in a first direction along the rotation axis when the rotating member rotates in a first rotation direction around the rotation axis, and is movable in a second direction opposite to the first direction when the rotating member rotates in a second rotation direction opposite to the first direction. A brake pad spaced apart from the linear motion member in the first direction, A piston is provided, which is restricted from rotating about the rotation axis relative to the linear motion member and is movable along the rotation axis relative to the linear motion member, and which is able to push the brake pad in the first direction when pushed in the first direction by the linear motion member, A protrusion protrudes from the brake pad and is housed in a recess provided in the piston, and has an inclined surface that is obliquely tilted with respect to the axis of rotation, It is equipped with, The piston, rotated in the second rotational direction, contacts the inclined surface of the brake pad with the first recessed end face and pushes the brake pad in the first direction. When the protrusion is viewed in the first direction, the projected area of ​​the inclined surface is greater than half the projected area of ​​the protrusion. The inclined surface has a first edge provided at the end of the inclined surface in the first rotation direction, and a second edge provided at the end of the inclined surface in the second rotation direction and parallel to the first edge, and extends flat between the first edge and the second edge. Braking device.

2. The first end face of the recess and the second end face of the recess that contacts the protrusion when the piston is rotated in the first rotational direction are each provided parallel to the axis of rotation. The braking device according to claim 1.

3. The convex portion has a restricting surface that contacts the second end surface of the recess when the piston is rotated in the first rotational direction, thereby restricting the piston from rotating in the first rotational direction. In the projection plane viewed in the first direction, the first edge and the restricting surface each extend in a straight line, the extension of the first edge and the extension of the restricting surface intersect in the region between the protrusion and the axis of rotation, and the extension of the first end face of the recess and the extension of the second end face of the recess intersect at a position closer to the axis of rotation than the intersection of the extension of the first edge and the extension of the restricting surface. The braking device according to claim 2.

4. A rotating member having either a male screw or a female screw that meshes with the male screw, and being rotatable around a rotation axis, An electric motor that rotates the aforementioned rotating member, A linear motion member is provided with the other of the male and female threads, and is movable in a first direction along the rotation axis when the rotating member rotates in a first rotation direction around the rotation axis, and is movable in a second direction opposite to the first direction when the rotating member rotates in a second rotation direction opposite to the first direction. A brake pad spaced apart from the linear motion member in the first direction, A piston is provided, which is restricted from rotating about the rotation axis relative to the linear motion member and is movable along the rotation axis relative to the linear motion member, and which is able to push the brake pad in the first direction when pushed in the first direction by the linear motion member, A protrusion protrudes from the brake pad and is housed in a recess provided in the piston, and has an inclined surface that is obliquely tilted with respect to the axis of rotation, It is equipped with, The piston, rotated in the second rotational direction, contacts the inclined surface of the brake pad with the first recessed end face and pushes the brake pad in the first direction. When the protrusion is viewed in the first direction, the projected area of ​​the inclined surface is greater than half the projected area of ​​the protrusion. The inclined surface has a first edge provided at the end of the inclined surface in the first rotational direction and extending linearly, and a second edge provided at the end of the inclined surface in the second rotational direction and extending linearly, In the projection plane viewed from the first direction, the extension of the first edge and the extension of the second edge intersect at the axis of rotation, or in the region between the protrusion and the axis of rotation. Braking device.

Images