Brake device

Abstract

A brake device according to an embodiment of the present invention is provided with: a rotating member; a linear motion member movable in a first direction when the rotating member rotates in a first rotational direction and movable in a second direction when the rotating member rotates in a second rotational direction; a piston capable of pressing a brake pad in the first direction by being pressed in the first direction by the linear motion member; and a protruding portion that protrudes from the brake pad, is housed in a recess provided in the piston, and has an inclined surface inclined with respect to the rotating shaft, the piston rotating in the second rotational direction being in contact with the inclined surface of the brake pad at a first end surface of the recess, and presses the brake pad in the first direction, and the piston rotating in the second rotational direction being in contact with the inclined surface of the brake pad at a second end surface of the recess. When the projection is viewed in the first direction, the projected area of the inclined surface is larger than half of the projected area of the projection.

Description

Technical Field

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

[0002] Conventionally, a brake device is known in which the rotation of a rotating member driven by an electric motor is converted into the linear motion of a linear motion member, and a brake pad is pressed against a brake rotor via a piston by the linear motion member. In some cases, a convex portion and a concave portion that fit together to restrict the rotation of the piston are provided on the piston and the brake pad (Patent Document 1).

[0003] Patent Document 1: Japanese Patent Application Publication No. 2017-155774

[0004] However, in the previous structure, when the piston and the brake pad are restricted by the engagement of the convex and concave parts, a large load is applied to the electric motor and the mechanism for transmitting rotation between the electric motor and the rotating member. If this load is reduced, the durability of the brake device can be improved. Summary of the invention

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

[0006] As an example, a brake device according to an embodiment of the present invention comprises: a rotating member having an external thread and an internal thread meshing with the external thread, and capable of rotating around a rotating axis; an electric motor for rotationally driving the rotating member; a linear motion member having the other of the external thread and the internal thread, and capable of moving in a first direction along the rotating axis when the rotating member rotates in a first rotating direction around the rotating axis, and capable of moving in a second direction opposite to the first direction when the rotating member rotates in a second rotating direction opposite to the first rotating direction; a brake pad separated from the linear motion member in the first direction; and a piston restricted relative to the first direction. The linear motion component is rotatable about the rotation axis and can move along the rotation axis relative to the linear motion component, and can be pushed in the first direction by the linear motion component; and the convex portion protrudes from the brake pad and is accommodated in the concave portion provided in the piston, and has an inclined surface inclined relative to the rotation axis, and the piston rotating in the second rotation direction contacts the inclined surface of the brake pad at the first end face of the concave portion, and pushes the brake pad in the first direction, and when the convex portion is observed in the first direction, the projected area of ​​the inclined surface is larger than half of the projected area of ​​the convex portion. Thus, as an example, the inclination of the inclined surface relative to the plane orthogonal to the rotation axis is smaller than the case where the projected area of ​​the inclined surface is smaller than half of the projected area of ​​the convex portion. Therefore, when the piston rotates in the second rotation direction, the reaction force in the first rotation direction received by the first end face of the concave portion from the inclined surface becomes smaller. Therefore, for example, the load applied to 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 can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a cross-sectional view schematically showing the brake device according to the first embodiment.

[0008] Figure 2 It is along Figure 1 The F2 - F2 line shows a cross-sectional view of the piston and the brake pad according to the first embodiment.

[0009] Figure 3 It is a plan view showing the convex portion of the first embodiment.

[0010] Figure 4 It is along Figure 3 A cross-sectional view of a part of the braking device according to the first embodiment is shown along the line F4 - F4 .

[0011] Figure 5It is a plan view showing a part of a piston and a brake pad according to a second embodiment. DETAILED DESCRIPTION

[0012] (First Embodiment)

[0013] Below, refer to Figures 1 to 4 , the first embodiment is described. In addition, in this specification, there are cases where multiple expressions are used to record the constituent elements involved in the embodiment and the description of the elements. The constituent elements and their descriptions are examples and are not limited by the expressions in this specification. The constituent elements may also be designated by names different from the names in this specification. In addition, the constituent elements may also be described by expressions different from the expressions in this specification.

[0014] Figure 1 1 is a cross-sectional view schematically showing a brake device 10 according to the first embodiment. The brake device 10 is mounted on a vehicle 1 such as an automobile. The brake device 10 is not limited to this example. Figure 1 As shown, the brake device 10 includes a brake caliper 11 , a piston 12 , a piston seal 13 , a brake rotor 14 , a brake pad 15 , a rotation-to-linear motion conversion mechanism 16 , a rotation transmission mechanism 17 , an electric motor 18 , and an ECU 19 .

[0015] The brake device 10 can work as a hydraulic brake and can also work as an electric brake. For example, the brake caliper 11, the piston 12, the piston seal 13, the brake rotor 14, and the brake pad 15 constitute a hydraulic brake. In addition, the brake caliper 11, the piston 12, the piston seal 13, the brake rotor 14, the brake pad 15, the rotation-linear motion conversion mechanism 16, the rotation transmission mechanism 17, and the electric motor 18 constitute an electric brake. In addition, the brake device 10 is not limited to this example.

[0016] The electric brake is a so-called electric parking brake (EPB). That is, the brake device 10 is configured to maintain a braking state achieved by an electric brake function when the vehicle is parked. In addition, the electric brake can also be operated when the vehicle is traveling or temporarily stopped.

[0017] The brake caliper 11 is provided with a cylinder 21 . The cylinder 21 is a substantially cylindrical hole opened on the outer surface of the brake caliper 11 . Figure 1 The central axis Ax of the cylinder 21 is indicated 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. In addition, the rotation axis may be different from the central axis of the cylinder 21.

[0018] In this specification, axial, radial, and circumferential directions are defined for convenience. The axial direction is a direction along the central axis Ax, including a first direction Dt1 and a second direction Dt2. The second direction Dt2 is the opposite direction of the first direction Dt1. The radial direction is a direction orthogonal to the central axis Ax. The circumferential direction is a direction around the central axis Ax.

[0019] The cylinder 21 is a bottomed hole opened in the first direction Dt1. The piston 12 is accommodated in the cylinder 21 so as to be movable in the axial direction. In the cylinder 21, a hydraulic chamber R is provided between the piston 12 and a bottom surface 21a of the cylinder 21 in the second direction Dt2.

[0020] 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 radially outward 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.

[0021] The piston 12 is provided with a recessed portion 12c. The recessed portion 12c is a bottomed hole that is open in the second direction Dt2. The piston 12 forms a part of the hydraulic chamber R. The recessed portion 12c is formed in a substantially cylindrical shape, for example. In addition, the shape of the recessed portion 12c is not limited to this example.

[0022] 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 an inner surface of the caliper 11 formed in a substantially cylindrical shape facing inward in the radial direction of the central axis Ax.

[0023] 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 in the axial direction along the inner peripheral surface 21b while being lubricated by the hydraulic oil present in the gap.

[0024] The piston seal 13 is sandwiched 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. Thus, the piston seal 13 can suppress leakage of the hydraulic oil from the hydraulic chamber R through the gap.

[0025] The piston seal 13 is attached to the inner peripheral surface 21b of the cylinder 21, and is restricted from moving relative to the brake caliper 11. Alternatively, the piston seal 13 may be attached to the outer peripheral surface 12a of the piston 12.

[0026] 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.

[0027] The brake pad 15 is located between the piston 12 and the brake rotor 14. The brake pad 15 is supported by the caliper 11, for example, so as to be movable in parallel in the axial direction. The brake pad 15 includes a back plate 31 and a friction material 32.

[0028] The back 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 surface 12b of the piston 12 and the receiving surface 31a of the back 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 mounted on the mounting surface 31b and is located between the brake rotor 14 and the back plate 31.

[0029] When the hydraulic pressure in the hydraulic chamber R rises, the piston 12 is pushed by the hydraulic pressure in the first direction Dt1 and moves along the first direction Dt1. The piston 12 abuts against the receiving surface 31a of the back plate 31, and the friction material 32 is pressed against the brake rotor 14 by pressing the back plate 31. As a result, the wheels of the vehicle 1 are braked, and a braking state achieved by the hydraulic brake is obtained.

[0030] The piston seal 13 has a retracting function, that is, as the hydraulic pressure in the hydraulic chamber R decreases, the piston 12 is pulled in the second direction Dt2 by the elastic force, so that the end surface 12b of the piston 12 is separated from the back plate 31. That is, when the pressing of the piston 12 on the back plate 31 is released as the hydraulic pressure in the hydraulic chamber R decreases, the pressing of the friction material 32 on the brake rotor 14 by the piston 12 is released. As a result, the brake release state achieved by the hydraulic brake is obtained.

[0031] The rotation-to-linear motion conversion mechanism 16 includes a rotation member 41 and a linear motion member 42. The rotation member 41 and the linear motion member 42 are each at least partially accommodated in the cylinder 21. The rotation member 41 is supported by the brake caliper 11 so as to be rotatable around the central axis Ax. The linear motion member 42 is mounted on the rotation member 41 so as to be able to linearly move in the axial direction according to the rotation of the rotation member 41.

[0032] The rotation transmission mechanism 17 is, for example, a speed reducer having a plurality of rotating members such as gears. The rotation transmission mechanism 17 is located outside the cylinder 21 and is, for example, covered by a cover. The rotation 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 the central axis Ax by the torque input from the rotation transmission mechanism 17.

[0033] The rotating member 41 includes a coupling portion 51, a flange 52, and a shaft 53. The coupling portion 51 is coupled to an output gear of the rotation transmission mechanism 17 through a hole opened to the bottom surface 21a of the cylinder 21, for example, and rotates integrally with the output gear.

[0034] The flange 52 and the 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 disk shape extending from the coupling portion 51 and the shaft 53 in the radial direction.

[0035] The shaft 53 protrudes from the flange 52 in the first direction Dt1. The shaft 53 is formed in a substantially cylindrical shape extending in the axial direction along the central axis Ax. In the present embodiment, the central axis Ax is also the central axis of the flange 52 and the shaft 53.

[0036] A thrust bearing 55 is provided between the flange 52 and the bottom surface 21 a of the cylinder 21. The caliper 11 supports the rotating member 41 via the thrust bearing 55 in the axial direction.

[0037] The shaft 53 has an outer peripheral surface 53a. The outer peripheral surface 53a is a substantially cylindrical curved surface extending in the axial direction and facing radially outward. An external thread 57 is provided on the outer peripheral surface 53a.

[0038] The linear motion component 42 is formed into a generally cylindrical shape extending in the axial direction and surrounding the central axis Ax. The linear motion component 42 has an inner peripheral surface 42a and an outer peripheral surface 42b. The inner peripheral surface 42a is a generally cylindrical curved surface extending in the axial direction and facing radially inward. The outer peripheral surface 42b is located on the opposite side of the inner peripheral surface 42a. The outer peripheral surface 42b is a generally cylindrical curved surface extending in the axial direction and facing radially outward.

[0039] The inner peripheral surface 42a is provided with an internal thread 58. The internal thread 58 meshes with the external thread 57 of the rotating member 41. Alternatively, the rotating member 41 may be provided with an internal thread, and the linear motion member 42 may be provided with an external thread.

[0040] A portion of the rotation-to-linear motion conversion mechanism 16 is accommodated 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 provided inside the recess 12c so as to be movable in the axial direction.

[0041] A guide groove 12d extending in the axial direction is provided in the recessed portion 12c of the piston 12. For example, a protrusion 42c protruding from the outer peripheral surface 42b of the linear motion component 42 is embedded in the guide groove 12d. As a result, the piston 12 is restricted from rotating about the central axis Ax relative to the linear motion component 42, and the piston 12 can move axially relative to the linear motion component 42. In addition, the piston 12 and the linear motion component 42 can also be slightly relatively rotatable about the central axis Ax.

[0042] As described above, the external thread 57 of the rotating member 41 and the internal thread 58 of the linear motion member 42 are meshed, and the relative rotation of 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 according to the rotation of the rotating member 41. In other words, the linear motion member 42 can move substantially parallel to the axial direction.

[0043] The electric motor 18 is driven by driving power based on the control signal. The electric motor 18 rotates the output shaft of the electric motor 18 to drive the rotating member 41 to rotate around the central axis Ax via the rotation transmission mechanism 17 .

[0044] The brake pad 15 is separated from the linear motion member 42 in the first direction Dt1, and the piston 12 is located between the brake pad 15 and the linear motion member 42. The linear motion member 42 can press the brake pad 15 via the piston 12 according to the rotation of the rotating member 41.

[0045] Figure 2 It is along Figure 1 The F2 - F2 line shows a cross-sectional view of the piston 12 and the brake pad 15 according to the first embodiment. Figure 1 The rotating member 41 shown can be moved along Figure 2 The first rotation direction Dr1 and the second rotation direction Dr2 shown rotate. 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 of the first rotation direction Dr1.

[0046] When the output shaft of the electric motor 18 rotates in one direction, the rotating member 41 rotates in the first rotating direction Dr1. When the rotating member 41 rotates in the first rotating direction Dr1, the linear motion member 42 linearly advances (moves) in the first direction Dt1.

[0047] The linear motion member 42 moving in the first direction Dt1 presses the piston 12 in the first direction Dt1. The piston 12 pressed by the linear motion member 42 moves in the first direction Dt1, thereby coming into contact with the receiving surface 31a of the back plate 31 of the brake pad 15.

[0048] The piston 12 is pushed in the first direction Dt1 by the linear motion member 42, thereby pushing the back 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 back plate 31. Through the above, a braking state achieved by the electric brake function in which the wheel of the vehicle 1 rotating integrally with the brake rotor 14 is braked can be obtained.

[0049] When the output shaft of the electric motor 18 rotates in the opposite direction, the rotating member 41 rotates in the second rotating direction Dr2. When the rotating member 41 rotates in the second rotating direction Dr2, the linear motion member 42 moves linearly in the second direction Dt2 and moves away from the piston 12. By the movement of the linear motion member 42 in the second direction Dt2, the pressing force of the piston 12 on the back plate 31 is reduced, and the pressing of the friction material 32 on the brake rotor 14 by the piston 12 is released. As a result, the brake release state (non-braking state) achieved by the electric brake function is obtained.

[0050] In this embodiment, Figure 1 The ECU 19 controls the electric motor 18. The ECU 19 may be partially constituted by hardware such as a CPU or a controller that executes software, or may be entirely constituted by hardware. In addition, the electric motor 18 is not limited to the ECU 19, and may be controlled by a controller dedicated to the brake device 10, for example.

[0051] For example, when the ECU 19 receives an instruction signal for shifting to the braking state from the operation switch (SW) of the electric brake function, the ECU 19 controls the electric motor 18 to rotate the rotating member 41 in the first rotation direction Dr1. On the other hand, when the ECU 19 receives an instruction signal for releasing the braking state from the operation switch, the ECU 19 controls the electric motor 18 to rotate the rotating member 41 in the second rotation direction Dr2.

[0052] like Figure 2 As shown, the brake device 10 further includes an engagement structure 60 . The engagement structure 60 includes recessed portions 61 , 62 , and 63 provided on the piston 12 , and a convex portion 65 protruding from the brake pad 15 .

[0053] The recessed portions 61, 62, and 63 are recessed from the end surface 12b of the piston 12 in the second direction Dt2. The recessed portions 61 and 62 are separated from the central axis Ax in the radial direction outward and open to the outer peripheral surface 12a and the end surface 12b of the piston 12. The recessed portion 63 is provided along the central axis Ax and communicates with the recessed portion 61 and the recessed portion 62. In addition, the piston 12 may be provided with only the recessed portion 61.

[0054] The piston 12 has a first concave end face 61a that contacts the convex portion 65 of the back plate 31 when rotating in the second rotation direction Dr2, and a second concave end face 61b that contacts the convex portion 65 of the back plate 31 when rotating in the first rotation direction Dr1. In the present embodiment, the first concave end face 61a and the second concave end face 61b are planes that are substantially parallel to the central axis Ax. In addition, the first concave end face 61a and the second concave end face 61b are not limited to this example.

[0055] The first end face 61a of the recess is formed to be substantially flat and faces the second rotation direction Dr2. The second end face 61b of the recess is formed to be substantially flat and faces the first rotation direction Dr1. On the projection plane (projection plane) of the piston 12 observed along the second direction Dt2, the first end face 61a of the recess and the second end face 61b of the recess are respectively extended in a straight line. In the present embodiment, on the projection plane, the extension line of the first end face 61a of the recess and the extension line of the second end face 61b of the recess intersect at the central axis Ax. In addition, the first end face 61a of the recess and the second end face 61b of the recess are not limited to this example.

[0056] The convex portion 65 protrudes from the receiving surface 31a of the back plate 31 in the second direction Dt2 at a position separated from the central axis Ax in the radial direction to the outside. The convex portion 65 is at least partially accommodated in the concave portion 61. That is, the convex portion 65 is located between the concave portion first end face 61a and the concave portion second end face 61b of the concave portion 61 in the circumferential direction. In the circumferential direction, the length of the convex portion 65 is shorter than the distance between the concave portion first end face 61a and the concave portion second end face 61b of the concave portion 61.

[0057] Figure 3 FIG. 6 is a top view showing the convex portion 65 of the first embodiment. Figure 3 As shown, the convex portion 65 is formed in a block shape having a substantially trapezoidal cross section that tapers toward the central axis Ax. In addition, the convex portion 65 is not limited to this example. The convex portion 65 of this embodiment has an end surface 71, an inner surface 72, an outer surface 73, a limiting surface 74, and an inclined surface 75.

[0058] The end surface 71 is provided at the end of the convex portion 65 in the second direction Dt2. The end surface 71 is formed to be substantially flat and faces the second direction Dt2. That is, the end surface 71 is a plane substantially orthogonal to the axial direction.

[0059] 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.

[0060] 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.

[0061] The limiting surface 74 is an end portion of the convex portion 65 disposed on a side that contacts the second end surface 61b of the recess when the piston 12 rotates along the first rotation direction Dr1. The limiting surface 74 is a plane that is substantially parallel to the center axis Ax. In addition, the limiting surface 74 is not limited to this example. The limiting surface 74 is formed to be substantially flat. When the second end surface 61b of the recess contacts the convex portion 65, the limiting surface 74 faces the second end surface 61b of the recess. In addition, when the second end surface 61b of the recess contacts the convex portion 65, the limiting surface 74 faces the substantially opposite side of the direction that the second end surface 61b of the recess faces. However, in the present embodiment, the direction that the limiting surface 74 faces is slightly different from the opposite direction of the direction that the second end surface 61b of the recess faces.

[0062] The limiting surface 74 is connected to one end of the inner surface 72 close to the second end surface 61b of the recessed portion via the corner portion 76. Furthermore, the limiting surface 74 is connected to one end of the outer surface 73 close to the second end surface 61b of the recessed portion via the corner portion 77. The corner portions 76 and 77 are substantially semi-cylindrical curved surfaces. In addition, the corner portions 76 and 77 are not limited to this example.

[0063] Figure 4 It is along Figure 3 The F4-F4 line of FIG. 1 is a cross-sectional view of a portion of the braking device 10 according to the first embodiment. Figure 4 As shown, the inclined surface 75 is inclined relative to the central axis Ax. In other words, the inclined surface 75 is not orthogonal to the central axis Ax, and is not parallel to the central axis Ax.

[0064] 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. In other words, the first edge 81 is provided at one end of the inclined surface 75 close to the first end surface 61a of the recessed portion. The second edge 82 is provided at the end of the inclined surface 75 in the second rotation direction Dr2. In other words, the second edge 82 is provided at one end of the inclined surface 75 close to the second end surface 61b of the recessed portion. Therefore, the second edge 82 is closer to the limiting surface 74 than the first edge 81.

[0065] like Figure 3 As shown, one end 81a of the first edge 81 is connected to one end of the inner surface 72 close to the first end surface 61a of the recessed portion via a corner portion 85. Also, the other end 81b of the first edge 81 is connected to one end of the outer surface 73 close to the first end surface 61a of the recessed portion via a corner portion 86. The corner portions 85 and 86 are substantially semi-cylindrical curved surfaces. In addition, the corner portions 85 and 86 are not limited to this example.

[0066] 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 surface 71. In other words, the second edge 82 forms a boundary between the end surface 71 and the inclined surface 75. By providing the above inclined surface 75, the convex portion 65 gradually becomes thinner toward the second direction Dt2.

[0067] In the present embodiment, the first edge 81 and the second edge 82 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 flatly between the first edge 81 and the second edge 82.

[0068] In such Figure 2 In this way, on the projection surface of the convex portion 65 observed along the first direction Dt1, the first edge 81 and the limiting surface 74 extend in straight lines. On the projection surface, the extension line of the first edge 81 and the extension line of the limiting surface 74 intersect in the region Ab between the convex portion 65 and the central axis Ax. The region Ab is, for example, a 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.

[0069] In the present embodiment, on the projection plane of the convex portion 65 observed along the first direction Dt1, the intersection of the extension line of the first edge 81 and the extension line of the limiting surface 74 is located on the line connecting the center of the convex portion 65 in the circumferential direction and the central axis Ax. In addition, the intersection of the extension line of the first edge 81 and the extension line of the limiting surface 74 is not limited to this example.

[0070] On the other hand, on the projection plane of the convex portion 65 observed along the first direction Dt1, the extension line of the concave portion first end surface 61a and the extension line of the concave portion second end surface 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 restriction surface 74. In the present embodiment, as described above, the extension line of the concave portion first end surface 61a and the extension line of the concave portion second end surface 61b intersect at the central axis Ax. In addition, the extension line of the concave portion first end surface 61a and the extension line of the concave portion second end surface 61b may also intersect at other positions.

[0071] The protrusion 65 is formed on the back plate 31 by, for example, stamping. Therefore, a recess is provided on the mounting surface 31b of the back plate 31 at a position opposite to the protrusion 65. The protrusion 65 is not limited to this example, and may be formed by mounting a component different from the back plate 31 on the back plate 31, for example.

[0072] When the rotating member 41 rotates and the linear motion member 42 moves in the axial direction, the linear motion member 42 may rotate around the central axis Ax together with the rotating member 41 due to friction between the external thread 57 and the internal thread 58, for example. Since the protrusion 42c and the guide groove 12d are engaged with each other, the rotating linear motion member 42 rotates the piston 12 around the central axis Ax. That is, the piston 12 generates co-rotation with the rotating member 41 and the linear motion member 42.

[0073] When the piston 12 rotates in the first rotation direction Dr1, the limiting surface 74 of the convex portion 65 abuts against the concave second end surface 61b. The brake pad 15 is supported by the brake caliper 11 to limit the rotation of the brake pad 15. Therefore, the convex portion 65 provided on the brake pad 15 limits the piston 12 from further rotating in the first rotation direction Dr1. That is, when the piston 12 rotates in the first rotation direction Dr1, the convex portion 65 abuts against the concave second end surface 61b, thereby limiting the piston 12 from rotating in the first rotation direction Dr1. In this way, the engaging structure 60 limits the common rotation of the piston 12 in the first rotation direction Dr1.

[0074] The second end surface 61b of the recess and the limiting surface 74 are both planes substantially parallel to the central axis Ax. Therefore, the force (braking force) of the piston 12 pressing the brake pad 15 against the brake rotor 14 can be suppressed from changing while the second end surface 61b of the recess presses the limiting surface 74.

[0075] like Figure 4 As shown, when the piston 12 rotates in the second rotation direction Dr2, the inclined surface 75 of the convex portion 65 contacts the concave first end surface 61a. The concave first end surface 61a of the piston 12 driven in the second rotation direction Dr2 pushes the inclined surface 75 in the second rotation direction Dr2.

[0076] The friction between the external thread 57 and the internal thread 58 causes the force driving the piston 12 in the second rotational direction Dr2 to be relatively small. Therefore, the reaction force acting on the first end surface 61a of the recess from the inclined surface 75 limits the piston 12 from rotating in the second rotational direction Dr2. That is, the convex portion 65 limits the piston 12 from rotating further in the second rotational direction Dr2.

[0077] On the other hand, for example, in order to replace the brake pad 15, the rotating member 41 rotates in the second rotation direction Dr2, so that the linear motion member 42 moves to the maximum extent in the second direction Dt2. When the linear motion member 42 moves to the maximum extent in the second direction Dt2, the linear motion member 42 abuts against the flange 52 of the rotating member 41. In this case, the external thread 57 and the internal thread 58 are completely tightened, and the rotating member 41 and the linear motion member 42 are in a state of rotating as a whole (locked state). In the locked state, the force of the rotating member 41 to drive the linear motion member 42 and the piston 12 in the second rotation direction Dr2 becomes greater.

[0078] By driving the piston 12 in the second rotational direction Dr2, the first end surface 61a of the recessed portion pushes the inclined surface 75 in the second rotational direction Dr2. Since the inclined surface 75 is inclined as described above, the component force of the force of the piston 12 pushing the inclined surface 75 pushes the inclined surface 75 in the first direction Dt1. That is, the piston 12 rotating in the second rotational direction Dr2 contacts the inclined surface 75 at the first end surface 61a of the recessed portion, and pushes the brake pad 15 in the first direction Dt1. As a result, the brake pad 15 and the piston 12 are separated from each other.

[0079] The energy of the piston 12 pressing 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 applied to the electric motor 18 and the rotation transmission mechanism 17 is reduced. When the convex portion 65 is disengaged from the concave portion 61 due to the separation of the brake pad 15 and the piston 12, the load applied to the electric motor 18 and the rotation transmission mechanism 17 is further reduced.

[0080] In such Figure 3 In this way, when the convex portion 65 is observed along the first direction Dt1, the projected area of ​​the inclined surface 75 is larger than half of the projected area of ​​the convex portion 65. In the present 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 the limiting surface 74. That is, by providing the inclined surface 75, the limiting surface 74 is not damaged, and the durability of the convex portion 65 when the limiting surface 74 abuts against the second end surface 61b of the recessed portion is improved.

[0081] In the brake device 10 according to the first embodiment described above, the convex portion 65 protrudes from the brake pad 15 and is accommodated in the concave portion 61 provided in the piston 12. The convex portion 65 has an inclined surface 75 inclined relative to the central axis Ax. The piston 12 rotating in the second rotational direction Dr2 contacts the inclined surface 75 at the first end surface 61a of the concave portion and pushes the brake pad 15 in the first direction Dt1. When the convex portion 65 is observed in the first direction Dt1, the projected area of ​​the inclined surface 75 is larger than half of the projected area of ​​the convex portion 65. For example, in order to replace the brake pad 15, there is a case where the rotating member 41 is rotated in the second rotational direction Dr2 until the linear motion member 42 moves to the maximum in the second direction Dt2. When the linear motion member 42 moves to the maximum in the second direction Dt2, the linear motion member 42 and the rotating member 41 are in a state of integral rotation (locked state), and the rotating member 41, the linear motion member 42, and the piston 12 can be integrally rotated in the second rotational direction Dr2. In the above-mentioned brake device 10, the inclination of the inclined surface 75 relative to the plane orthogonal to the central axis Ax is smaller than the case where the projection area of ​​the inclined surface 75 is smaller than half the projection area of ​​the convex portion 65. Therefore, when the piston 12 rotates in the second rotation direction Dr2, the reaction force in the first rotation direction Dr1 received by the first end face 61a of the concave portion from the inclined surface 75 becomes smaller. Therefore, for example, the load applied to the electric motor 18 driving the rotating member 41 and the rotation transmission mechanism 17 transmitting the rotation between the electric motor 18 and the rotating member 41 is reduced, and the durability of the brake device 10 can be improved. In addition, compared with the case where the projection area of ​​the inclined surface 75 is smaller than half the projection area of ​​the convex portion 65, the inclined surface 75 of the above-mentioned brake device 10 can prolong the time from the piston 12 starting to rotate in the second rotation direction Dr2 to the time when the first end face 61a of the concave portion abuts against the inclined surface 75. Therefore, for example, the frequency of load applied to the electric motor 18 and the rotation transmission mechanism 17 due to the piston 12 stopping rotation before the recessed first end surface 61 a contacts the inclined surface 75 can be reduced, and the durability of the brake device 10 can be improved.

[0082] 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 flatly between the first edge 81 and the second edge 82. Thus, when the piston 12 rotates in the second rotation direction Dr2, the distance that the first end face 61a of the recess presses the inclined surface 75 becomes longer. In addition, when the piston 12 rotates in the second rotation direction Dr2, the reaction force variation in the first rotation direction Dr1 received by the first end face 61a of the recess from the inclined surface 75 is suppressed. Therefore, the load applied to the electric motor 18 and the rotation transmission mechanism 17 is alleviated, and the durability of the brake device 10 can be improved.

[0083] The first end face 61a of the recess and the second end face 61b of the recess that contacts the convex portion 65 when the piston 12 rotates in the first rotation direction Dr1 are respectively set to be parallel to the central axis Ax. If the first end face 61a of the recess is inclined relative to the central axis Ax, the contact area between the piston 12 and the brake pad 15 is reduced compared with the present embodiment in which the first end face 61a of the recess is parallel to the central axis Ax. In the brake device 10 of the present embodiment, since the first end face 61a of the recess is parallel to the central axis Ax, the change in the surface pressure between the piston 12 and the brake pad 15 caused by the design of the inclined surface 75 that is set so as to push the brake pad 15 in the first direction Dt1 when the piston 12 rotates in the second rotation direction Dr2 can be reduced. Therefore, the brake device 10 can eliminate the worry of generating howling (noise).

[0084] The convex portion 65 has a limiting surface 74 that limits the rotation of the piston 12 in the first rotation direction Dr1 by contacting the concave second end surface 61b when the piston 12 rotates in the first rotation direction Dr1. On the projection surface of the convex portion 65 observed in the first direction Dt1, the first edge 81 and the limiting surface 74 extend in a straight line. On the projection surface, the extension line of the first edge 81 and the extension line of the limiting surface 74 intersect in the area Ab between the convex portion 65 and the central axis Ax. On the other hand, on the projection surface, the extension line of the concave first end surface 61a and the extension line of the concave second end surface 61b intersect at a position closer to the central axis Ax than the intersection of the extension line of the first edge 81 and the extension line of the limiting surface 74. As a result, the concave first end surface 61a and the inclined surface 75 can abut at a position farther from the central axis Ax. Therefore, when the piston 12 rotates in the second rotation direction Dr2, the load generated between the concave first end surface 61a and the inclined surface 75 becomes smaller, and the durability of the brake device 10 can be improved.

[0085] (Second Embodiment)

[0086] Below, refer to Figure 5 , the second embodiment is described. In addition, in the following description of the embodiments, there is a case where a component having the same function as a component already described is marked with the same reference numeral as the component already described, and further description is omitted. In addition, multiple components marked with the same reference numeral are not limited to sharing all functions and properties, and may also have different functions and properties corresponding to each embodiment.

[0087] Figure 5 1 is a top view showing a portion of the piston 12 and the brake pad 15 according to the second embodiment. Figure 5 A cross section of the piston 12 is shown in FIG. Figure 5 As shown, the convex portion 65 of the second embodiment has an inclined surface 90 instead of the inclined surface 75. The inclined surface 90 is substantially the same as the inclined surface 75 of the first embodiment except for the points described below.

[0088] 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 for the points described below. The second edge 92 extends in a straight line. However, the second edge 92 of the second embodiment is different from the second edge 82 of the first embodiment and is not parallel to the first edge 81.

[0089] In such Figure 5 Thus, when the projection 65 is viewed along the first direction Dt1, the extension lines of the first edge 81 and the second edge 92 intersect in the region Ab between the projection 65 and the central axis Ax. Alternatively, the extension lines of the first edge 81 and the second edge 92 may intersect at the central axis Ax.

[0090] In the present embodiment, on the projection plane of the convex portion 65 viewed along the first direction Dt1, the intersection of the extension line of the first edge 81 and the extension line of the second edge 92 is located on the line connecting the center of the convex portion 65 in the circumferential direction and the central axis Ax. In addition, the intersection of the extension line of the first edge 81 and the extension line of the second edge 92 is not limited to this example.

[0091] In the brake 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 in a straight line. The second edge 92 is provided at the end of the inclined surface 90 in the second rotation direction Dr2 and extends in a straight line. On the projection surface of the convex portion 65 observed along the first direction Dt1, the extension line of the first edge 81 and the extension line of the second edge 92 intersect at the central axis Ax, or intersect in the area 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. Thus, when the piston 12 rotates in the second rotation direction Dr2, the first end face 61a of the concave portion and the inclined surface 90 can always be in linear contact. Therefore, the surface pressure between the first end face 61a of the concave portion and the inclined surface 90 is reduced, and damage to the brake pad 15 and the piston 12 is suppressed.

[0092] In the above embodiment, the first edge 81 and the second edge 82, 92 of the inclined surface 75, 90 extend in a straight line. However, the first edge and the second edge of the inclined surface are not limited to these examples, and may extend in a curved line.

[0093] As an example, the brake device involved in at least one of the embodiments described above comprises: a rotating member, which is provided with one of an external thread and an internal thread meshing with the external thread, and can rotate around a rotating axis; an electric motor, which rotationally drives the above-mentioned rotating member; a linear motion member, which is provided with the other of the above-mentioned external thread and the above-mentioned internal thread, and when the above-mentioned rotating member rotates in a first rotation direction around the above-mentioned rotating axis, it can move in a first direction along the above-mentioned rotating axis, and when the above-mentioned rotating member rotates in a second rotation direction opposite to the above-mentioned first rotation direction, it can move in a second direction opposite to the above-mentioned first direction; a brake pad, which is separated from the above-mentioned linear motion member in the above-mentioned first direction; a piston, which is The brake pad is limited to rotate around the rotation axis relative to the linear motion component and can move along the rotation axis relative to the linear motion component, and can be pushed in the first direction by the linear motion component; and the convex portion protrudes from the brake pad and is accommodated in the concave portion provided in the piston, and has an inclined surface inclined relative to the rotation axis, and the piston rotates in the second rotation direction and contacts the inclined surface of the brake pad at the first end surface of the concave portion, and pushes the brake pad in the first direction, and when the convex portion is observed in the first direction, the projected area of ​​the inclined surface is larger than half of the projected area of ​​the convex portion. For example, there is a case where the rotating component is rotated in the second rotation direction until the linear motion component moves to the maximum extent in the second direction in order to replace the brake pad. When the linear motion component moves to the maximum extent in the second direction, the linear motion component and the rotating component are in a state of rotating as a whole (locked state), and the rotating component, the linear motion component, and the piston can rotate as a whole in the second rotation direction. In the above-mentioned braking device, the inclination of the inclined surface relative to the plane orthogonal to the rotation axis is smaller than the case where the projection area of ​​the inclined surface is smaller than half the projection area of ​​the convex portion. Therefore, when the piston is driven in the second rotation direction, the reaction force in the first rotation direction received by the first end face of the concave portion from the inclined surface becomes smaller. Therefore, for example, the load applied to the electric motor driving the rotating component and the rotation transmission mechanism transmitting the rotation between the electric motor and the rotating component is reduced, and the durability of the braking device can be improved. In addition, compared with the case where the projection area of ​​the inclined surface is smaller than half the projection area of ​​the convex portion, the inclined surface of the above-mentioned braking device can extend the time from the piston starting to rotate in the second rotation direction to the first end face of the concave portion abutting against the inclined surface. Therefore, for example, the frequency of applying load to the electric motor and the driving mechanism due to the stop of the rotation of the piston before the first end face of the concave portion abuts against the inclined surface can be reduced, and the durability of the braking device can be improved.

[0094] In the above-mentioned braking device, as an example, the above-mentioned inclined surface has a first edge arranged at the end of the inclined surface in the above-mentioned first rotation direction, and a second edge arranged at the end of the inclined surface in the above-mentioned second rotation direction and parallel to the above-mentioned first edge, extending flatly between the above-mentioned first edge and the above-mentioned second edge. Therefore, as an example, when the piston is driven in the second rotation direction, the distance that the first end face of the recess pushes the inclined surface becomes longer. In addition, when the piston is driven in the second rotation direction, the reaction force variation in the first rotation direction received by the first end face of the recess from the inclined surface is suppressed. Therefore, the load applied to the electric motor and the drive mechanism is alleviated, and the durability of the braking device can be improved.

[0095] In the above-mentioned braking device, as an example, the first end face of the above-mentioned recess and the second end face of the recess that contacts the above-mentioned convex portion when the above-mentioned piston rotates along the above-mentioned first rotation direction are respectively set to be parallel to the above-mentioned rotation axis. For example, if the first end face of the recess and the second end face of the recess are inclined relative to the rotation axis, the contact area between the piston and the brake pad is reduced compared with the case where the first end face of the recess and the second end face of the recess are parallel to the rotation axis. In the above-mentioned braking device, since the first end face of the recess and the second end face of the recess are parallel to the rotation axis, it is possible to reduce the change in the surface pressure between the piston and the brake pad caused by the design of the inclined surface that pushes the brake pad in the first direction when the piston is driven along the second rotation direction. Therefore, the braking device can eliminate the worry of generating howling (noise).

[0096] In the above-mentioned braking device, as an example, the above-mentioned convex portion has a limiting surface that limits the rotation of the above-mentioned piston along the first rotation direction by contacting the second end surface of the above-mentioned concave portion when the above-mentioned piston rotates along the above-mentioned first rotation direction. On the projection surface of the above-mentioned convex portion observed along the above-mentioned first direction, the above-mentioned first edge and the above-mentioned limiting surface are respectively extended in a straight line, and the extension line of the above-mentioned first edge and the extension line of the above-mentioned limiting surface intersect in the area between the above-mentioned convex portion and the above-mentioned rotation axis, and the extension line of the above-mentioned first end surface of the concave portion and the extension line of the above-mentioned second end surface of the concave portion intersect at a position closer to the above-mentioned rotation axis than the intersection point of the extension line of the above-mentioned first edge and the extension line of the above-mentioned limiting surface. Thus, as an example, the first end surface of the concave portion and the inclined surface can abut against each other at a position farther away from the rotation axis. Therefore, when the piston rotates along the second rotation direction, the load generated between the first end surface of the concave portion and the inclined surface becomes smaller, and the durability of the braking device can be improved.

[0097] In the above-mentioned braking device, as an example, the above-mentioned inclined surface has a first edge which is arranged at the end of the inclined surface in the above-mentioned first rotation direction and extends in a straight line, and a second edge which is arranged at the end of the inclined surface in the above-mentioned second rotation direction and extends in a straight line, and on the projection surface of the above-mentioned convex portion observed along the above-mentioned first direction, the extension line of the above-mentioned first edge and the extension line of the above-mentioned second edge intersect at the above-mentioned rotation axis, or intersect in the area between the above-mentioned convex portion and the above-mentioned rotation axis. Therefore, as an example, the first edge and the second edge extend radially from a point near the rotation axis. Thus, when the piston is driven in the second rotation direction, the first end face of the recess and the inclined surface can be in linear contact at all times. Therefore, the surface pressure between the first end face of the recess and the inclined surface is reduced, thereby suppressing damage to the brake pad and the piston.

[0098] In the above description, inhibition is defined as, for example, preventing the occurrence of an event, action or influence, or reducing the extent of an event, action or influence. In addition, in the above description, restriction is defined as, for example, preventing movement or rotation, or allowing movement or rotation within a specified range and preventing movement or rotation beyond the specified range.

[0099] The above examples illustrate the embodiments of the present invention, but the above embodiments and variations are only examples and are not intended to limit the scope of the invention. The above embodiments and variations can be implemented in various other ways, and various omissions, substitutions, combinations, and changes can be made without departing from the scope of the purpose of the invention. In addition, the structures and shapes of the embodiments and variations can also be partially replaced and implemented.

Claims

1. A braking device comprising: A rotating member having an external thread and an internal thread meshing with the external thread, and capable of rotating around a rotating axis; an electric motor for rotationally driving the rotating member; A linear motion component, provided with the other of the external thread and the internal thread, capable of moving in a first direction along the rotation axis when the rotation component rotates in a first rotation direction around the rotation axis, and capable of moving in a second direction opposite to the first direction when the rotation component rotates in a second rotation direction opposite to the first rotation direction; A brake pad separated from the linear motion component in the first direction; a piston 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 is capable of pressing the brake pad in the first direction by being pressed in the first direction by the linear motion member; and The convex portion protrudes from the brake pad and is accommodated in the concave portion provided in the piston, and has an inclined surface inclined relative to the rotation axis. The piston rotating in the second rotation direction contacts the inclined surface of the brake pad at the first end surface of the recess and presses the brake pad in the first direction. When the convex portion is viewed along the first direction, a projected area of ​​the inclined surface is larger than a half of a projected area of ​​the convex portion.

2. The braking device according to claim 1, wherein: The inclined surface has a first edge and a second edge, the first edge is arranged at the end of the inclined surface in the first rotation direction, the second edge is arranged at the end of the inclined surface in the second rotation direction and is parallel to the first edge, and extends flatly between the first edge and the second edge.

3. The braking device according to claim 2, wherein: The first end surface of the recessed portion and the second end surface of the recessed portion are respectively provided in parallel with the rotation axis, and the second end surface of the recessed portion contacts the convex portion when the piston rotates in the first rotation direction.

4. The braking device according to claim 3, wherein: The convex portion has a limiting surface, which limits the rotation of the piston in the first rotation direction by contacting with the second end surface of the concave portion when the piston rotates in the first rotation direction. On the projection surface of the convex portion observed along the first direction, the first edge and the limiting surface extend in straight lines respectively, the extension line of the first edge and the extension line of the limiting surface intersect in the area between the convex portion and the rotation axis, and the extension line of the first end surface of the concave portion and the extension line of the second end surface of the concave portion intersect at a position closer to the rotation axis than the intersection of the extension line of the first edge and the extension line of the limiting surface.

5. The braking device according to claim 1, wherein: The inclined surface has a first edge and a second edge, the first edge is provided at an end of the inclined surface in the first rotation direction and extends in a straight line, and the second edge is provided at an end of the inclined surface in the second rotation direction and extends in a straight line. On a projection surface of the convex portion viewed along the first direction, an extension line of the first edge and an extension line of the second edge intersect at the rotation axis, or at a region between the convex portion and the rotation axis.

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