Electric brake device and method of manufacturing the same

Abstract

As an example, an electric brake device capable of suppressing the generation of abnormal noise is obtained. [Solution] As an example, an electric brake device according to an embodiment includes a moving mechanism having a cable and configured to be moved by the tension of the cable to bring a braking member into contact with a drum rotor; a rotating member; a motor that drives the rotating member to rotate around a rotation axis; a linear-motion member that is attached to the rotating member and configured to pull the cable by moving in the axial direction along the rotation axis in response to the rotation of the rotating member around the rotation axis; a case that houses at least a portion of the rotating member; and a rolling bearing that has an inner ring in which the rotating member is press-fitted, an outer ring press-fitted into the case, and rolling elements that roll between the inner ring and the outer ring, and that supports the rotating member rotatably around the rotation axis relative to the case.

Description

[Technical Field]

[0001] FIELD Embodiments of the present invention relate to an electric brake device and a method for manufacturing an electric brake device. [Background technology]

[0002] Conventionally, electric brake devices that move brake shoes by pulling a cable have been known, and the electric brake device includes, for example, a case, a rotating member rotatably supported by the case, and a linearly-acting member that pulls the cable in response to rotation of the rotating member.

[0003] When the linear motion member pulls the cable, the rotating member is pulled by the tension of the cable via the linear motion member, and the tension holds the rotating member to the case via, for example, a thrust bearing (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-058092 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in conventional configurations, when the linear member is not pulling the cable, the tension is reduced or eliminated, which allows the rotating member to move relative to the case, which can cause noise due to, for example, collision with the thrust bearing during vibration.

[0006] Therefore, the present invention has been made in view of the above, and provides an electric brake device and a method for manufacturing an electric brake device that can suppress the generation of abnormal noise. [Means for solving the problem]

[0007] As an example, an electric brake device according to an embodiment of the present invention includes: a braking member configured to brake a wheel by contacting a drum rotor that rotates integrally with the wheel; a moving mechanism having a cable and configured to bring the braking member into contact with the drum rotor by being moved by the tension of the cable; a rotating member; a motor that drives the rotating member to rotate about a rotation axis; a linear motion member attached to the rotating member and configured to pull the cable by moving in an axial direction along the rotation axis in response to rotation of the rotating member about the rotation axis; a case that houses at least a portion of the rotating member; and a rolling bearing that has an inner ring in which the rotating member is shrink-fitted, an outer ring that is shrink-fitted to the case, and rolling elements that roll between the inner ring and the outer ring, and that supports the rotating member rotatably about the rotation axis relative to the case. Therefore, for example, the rolling bearing restricts relative axial movement between the rotating member and the case because the inner ring is interference-fitted to the rotating member and the outer ring is interference-fitted to the case, and therefore the electric brake device can restrict axial movement of the rotating member relative to the case, thereby suppressing the generation of abnormal noise due to relative movement between the rotating member and the case. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a side view showing an electric brake device according to one embodiment. [Figure 2] FIG. 2 is a rear view showing the electric brake device of the embodiment. [Figure 3] FIG. 3 is a cross-sectional view showing the MGU of the above embodiment. [Figure 4] FIG. 4 is a cross-sectional view showing a part of the MGU of the above embodiment. [Figure 5] FIG. 5 is a cross-sectional view showing the bearing, the screw shaft, and the lower case in the assembly of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment will be described below with reference to FIGS. 1 to 5. In this specification, components according to the embodiment and descriptions of the components may be described using multiple expressions. The components and their descriptions are merely examples and are not limited by the expressions in this specification. The components may also be identified by names different from those in this specification. Furthermore, the components may also be described using expressions different from those in this specification.

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

[0011] FIG. 1 is a side view showing an electric brake device 10 according to this embodiment. FIG. 2 is a rear view showing the electric brake device 10 according to this embodiment. As shown in FIG. 2, the electric brake device 10 is a drum brake mounted on a vehicle 1 such as an automobile. The electric brake device 10 may also be referred to as a braking device.

[0012] The electric brake device 10 is disposed inside the cylindrical peripheral wall 2a of the wheel 2. The electric brake device 10 may be disposed inside either a driving wheel or a non-driving wheel 2. However, the electric brake device 10 is not limited to this example.

[0013] As shown in Figures 1 and 2, for convenience, an X-axis, a Y-axis, and a Z-axis are defined in this specification. The X-axis, the Y-axis, and the Z-axis are perpendicular to one another. The X-axis is provided along the width of the electric braking device 10. The Y-axis is provided along the thickness of the electric braking device 10. The Z-axis is provided along the height of the electric braking device 10. The X-axis extends substantially in the front-rear direction of the vehicle 1. Furthermore, the Y-axis extends substantially in the width direction (vehicle width direction) of the vehicle 1.

[0014] Furthermore, in this specification, the X direction, Y direction, and Z direction are defined. The X direction (front-rear direction) is a direction along the X axis and includes the +X direction indicated by the X axis arrow and the -X direction opposite to the X axis arrow. The Y direction (vehicle width direction) is a direction along the Y axis and includes the +Y direction indicated by the Y axis arrow (outer side in the vehicle width direction) and the -Y direction opposite to the Y axis arrow (inner side in the vehicle width direction). The Z direction (height direction) is a direction along the Z axis and includes the +Z direction indicated by the Z axis arrow (upward) and the -Z direction opposite to the Z axis arrow (downward).

[0015] 1, the electric brake device 10 includes two brake shoes 11, a backing plate 12, an anchor 13, a wheel cylinder 14, a motor gear unit (MGU) 15, a spring 16, and a movement mechanism 17. The brake shoes 11 are an example of a braking member.

[0016] The two brake shoes 11 are spaced apart from each other in the X direction. The two brake shoes 11 extend in a substantially arc shape along the cylindrical inner circumferential surface 3a of the drum rotor 3 shown in Fig. 2. The drum rotor 3 may also be referred to as a brake drum.

[0017] The drum rotor 3 is attached to the wheel 2. The drum rotor 3 rotates integrally with the wheel 2 around a central axis Axd extending in the Y direction. The central axis Axd is the central axis of the wheel 2 and the drum rotor 3.

[0018] The backing plate 12 is formed in a substantially disk shape and disposed so as to be substantially perpendicular to the central axis Axd. The backing plate 12 is connected to the body of the vehicle 1, for example, via a part of the suspension. The backing plate 12 supports various elements of the electric brake device 10.

[0019] The anchor 13 is attached to the backing plate 12 near the end of the backing plate 12 in the -Z direction. The wheel cylinder 14 is attached to the backing plate 12 near the end of the backing plate 12 in the +Z direction. The two brake shoes 11, the anchor 13, the wheel cylinder 14, the spring 16, and the movement mechanism 17 are located outside the backing plate 12 in the vehicle width direction. On the other hand, the MGU 15 is attached to the backing plate 12 so as to protrude inward from the backing plate 12 in the vehicle width direction.

[0020] An end 11a of the brake shoe 11 in the -Z direction is supported by the anchor 13 so as to be rotatable around the end 11a. As a result, the brake shoe 11 is supported by the backing plate 12 via the anchor 13. Furthermore, an end 11b of the brake shoe 11 in the +Z direction is supported by a movable part of the wheel cylinder 14.

[0021] Each of the two brake shoes 11 has a strip-shaped lining 11c. The electric brake device 10 moves the two brake shoes 11 so as to press the lining 11c against the inner circumferential surface 3a of the drum rotor 3. The brake shoes 11 come into contact with the drum rotor 3, which rotates integrally with the wheel 2, and brake the wheel 2 due to friction between the lining 11c and the inner circumferential surface 3a of the drum rotor 3.

[0022] For example, the electric brake device 10 moves the brake shoes 11 using hydraulic pressure in the wheel cylinders 14 while the vehicle 1 is traveling. On the other hand, when the vehicle 1 is parking, the electric brake device 10 moves the brake shoes 11 using the MGU 15. In other words, the electric brake device 10 is a so-called electric parking brake. Note that the MGU 15 may move the brake shoes 11 while the vehicle 1 is traveling.

[0023] The wheel cylinder 14 presses the end portions 11b of the brake shoes 11 in response to the hydraulic pressure. This causes the two brake shoes 11 to rotate around the end portions 11a, and the end portions 11b of the two brake shoes 11 to move away from each other in the X direction. This causes the two brake shoes 11 to move toward the inner circumferential surface 3a of the drum rotor 3, and the linings 11c are pressed against the inner circumferential surface 3a of the drum rotor 3.

[0024] The spring 16 pulls the two brake shoes 11 toward each other. When the wheel cylinder 14 stops pressing the brake shoes 11, the spring 16 moves the two brake shoes 11 away from the inner peripheral surface 3a of the drum rotor 3.

[0025] The MGU 15 moves the two brake shoes 11 via a movement mechanism 17. The movement mechanism 17 has a lever 21, a pin 22, a cable 23, and a strut 24. Note that the components included in the movement mechanism 17 are not limited to this example.

[0026] The lever 21, one brake shoe 11 (11L), and backing plate 12 are aligned in a direction along the central axis Axd. A pin 22 attaches an end 21a of the lever 21 in the +Z direction to the brake shoe 11L near the end 11b. The lever 21 and the brake shoe 11L are attached to each other so as to be rotatable relative to each other around the pin 22.

[0027] The cable 23 passes through the backing plate 12 and extends between the MGU 15 and the lever 21. One end 23a of the cable 23 is attached to the end 21b of the lever 21 in the -Z direction. The MGU 15 can pull the lever 21 via the cable 23 so that the end 21b of the lever 21 approaches the central axis Axd.

[0028] The strut 24 is interposed between the lever 21 attached to one brake shoe 11L and the other brake shoe 11 (11R). The strut 24 abuts against the lever 21 between the two ends 21a, 21b of the lever 21.

[0029] Fig. 3 is a cross-sectional view showing the MGU 15 of this embodiment. As shown in Fig. 3, the MGU 15 has a housing 31, a motor 32, a speed reduction mechanism 33, a motion conversion mechanism 34, a bearing 35, and a cable end 36. The bearing 35 is an example of a rolling bearing.

[0030] The housing 31 accommodates the other end 23b of the cable 23, the motor 32, the speed reduction mechanism 33, the motion conversion mechanism 34, the bearings 35, and the cable end 36. The housing 31 is attached to the backing plate 12, for example, by bolts.

[0031] The motor 32 has an output shaft 41. The motor 32 is controlled by a control device such as an ECU to rotate the output shaft 41. The motor 32 may also be referred to as an actuator.

[0032] The reduction mechanism 33 has a plurality of gears 45, 46, and 47 rotatably supported on the housing 31, and a support shaft 48. The gear 45 is attached to the output shaft 41 of the motor 32. The gear 46 is supported on the support shaft 48. The gears 45 and 46 mesh with each other, and the gears 46 and 47 mesh with each other. The reduction mechanism 33 reduces the rotation of the output shaft 41 and transmits it to the motion conversion mechanism 34.

[0033] The motion conversion mechanism 34 has a threaded shaft 51 and a nut 52. The threaded shaft 51 is an example of a rotating member. The nut 52 is an example of a linearly moving member. The threaded shaft 51 and the nut 52 are each a metal component. However, the threaded shaft 51 and the nut 52 may be made of other materials.

[0034] The screw shaft 51 and the nut 52 are each formed in a substantially cylindrical shape extending along a central axis Axc. The central axis Axc is an example of a rotation axis, and is, for example, the central axis of the screw shaft 51 and the nut 52. Note that the screw shaft 51 and the nut 52 may be formed in other shapes.

[0035] For convenience, the terms axial, radial, and circumferential are defined herein. The axial direction is the direction along the central axis Axc. The axial direction includes a first axial direction Dx1 that is one direction along the central axis Axc and a second axial direction Dx2 that is opposite to the first axial direction Dx1. The radial direction is the direction perpendicular to the central axis Axc. The circumferential direction is the direction around the central axis Axc.

[0036] The screw shaft 51 has a cylindrical wall 55 and a flange 56. The cylindrical wall 55 is formed in a generally cylindrical shape extending along the central axis Axc. The flange 56 is formed in a generally disk shape protruding radially outward from the cylindrical wall 55. The gear 47 of the reduction mechanism 33 is provided at the end of the flange 56 on the radially outer side.

[0037] The gear 47 provided on the flange 56 can transmit rotation between the output shaft 41 and the gear 47 via other gears 45, 46 included in the reduction gear mechanism 33. Therefore, the motor 32 drives the screw shaft 51 via the reduction gear mechanism 33 to rotate around the central axis Axc.

[0038] The cylindrical wall 55 has a first outer peripheral surface 55a, a second outer peripheral surface 55b, and a male thread (external thread / bolt thread) 55c. The first outer peripheral surface 55a and the second outer peripheral surface 55b are substantially cylindrical curved surfaces extending along the central axis Axc and facing radially outward.

[0039] The first outer peripheral surface 55a extends in the first axial direction Dx1 from the flange 56. The second outer peripheral surface 55b extends in the second axial direction Dx2 from the flange 56. A male thread 55c is provided on the first outer peripheral surface 55a.

[0040] The cable 23 extends in the axial direction, passing through the inside of the substantially cylindrical tube wall 55. Inside the housing 31, the cable 23 extends, for example, along the central axis Axc. That is, the central axis Axc is also the central axis of the cable 23 inside the housing 31. However, the central axis Axc is not limited to this example.

[0041] The nut 52 is spaced apart from the flange 56 in the first axial direction Dx1 and surrounds a first outer peripheral surface 55a of the cylindrical wall 55. The nut 52 has an end face 52a, an inner peripheral surface 52b, an internal thread / nut thread 52c, and an outer peripheral surface 52d.

[0042] The end surface 52a is provided at an end of the nut 52 in the first axial direction Dx1. The inner circumferential surface 52b is a generally cylindrical curved surface extending along the central axis Axc and facing radially inward. In other words, the inner circumferential surface 52b faces the central axis Axc.

[0043] The female thread 52c is provided on the inner circumferential surface 52b. The female thread 52c and the male thread 55c mesh with each other, thereby attaching the nut 52 to the screw shaft 51. The outer circumferential surface 52d is located on the opposite side of the inner circumferential surface 52b. The outer circumferential surface 52d is a substantially cylindrical curved surface that extends along the central axis Axc and faces radially outward.

[0044] For example, the nut 52 further has a protrusion protruding from the outer peripheral surface 52d. The protrusion is supported by the housing 31 so as to be movable in the axial direction. That is, the housing 31 restricts the rotation of the nut 52 around the central axis Axc and supports the nut 52 so as to be movable in the axial direction. Note that the rotation of the nut 52 around the central axis Axc may be restricted by other methods.

[0045] Fig. 4 is a cross-sectional view showing a portion of the MGU 15 of this embodiment. As shown in Fig. 4, the bearing 35 is, for example, a radial ball bearing. However, the bearing 35 may be another rolling bearing that supports a radial load, such as an angular ball bearing, a cylindrical roller bearing, a needle roller bearing, or a tapered roller bearing.

[0046] The bearing 35 includes an inner ring 61, an outer ring 62, a plurality of rolling elements 63, and a cage 64. The bearing 35 may further include other components such as a seal. The inner ring 61 and the outer ring 62 may also be referred to as raceways.

[0047] The inner ring 61 is formed in a generally cylindrical shape extending along the central axis Axc. The inner ring 61 has an inner circumferential surface 61a and an end face 61b. The inner circumferential surface 61a is a generally cylindrical curved surface extending along the central axis Axc. The inner circumferential surface 61a forms the inner circumferential surface of the bearing 35 and faces the central axis Axc.

[0048] The end face 61b is located at an end of the inner ring 61 in the first axial direction Dx1. The end face 61b is located at an end of the bearing 35 in the first axial direction Dx1. The end face 61b is a substantially annular flat surface extending in the circumferential direction and facing the first axial direction Dx1.

[0049] The outer ring 62 is formed in a generally cylindrical shape extending along the central axis Axc. The outer ring 62 is spaced radially outward from the inner ring 61 and surrounds the inner ring 61, the rolling elements 63, and the cage 64. The outer ring 62 has an outer peripheral surface 62a and an end face 62b.

[0050] The outer peripheral surface 62a is a substantially cylindrical curved surface extending along the central axis Axc. The outer peripheral surface 62a forms the outer peripheral surface of the bearing 35. That is, in the entire bearing 35, the outer peripheral surface 62a is located on the opposite side of the inner peripheral surface 61a.

[0051] The end face 62b is located at an end of the outer ring 62 in the second axial direction Dx2. The end face 62b is also located at an end of the bearing 35 in the second axial direction Dx2. That is, the end face 62b is located opposite the end face 61b across the entire bearing 35. The end face 62b is a substantially annular flat surface extending in the circumferential direction and facing the second axial direction Dx2.

[0052] The rolling elements 63 are balls. The multiple rolling elements 63 are arranged in the circumferential direction between the inner ring 61 and the outer ring 62. The multiple rolling elements 63 fit into the raceways of the inner ring 61 and the outer ring 62. Therefore, the inner ring 61 and the outer ring 62 are attached to each other via the rolling elements 63, and the relative movement of the inner ring 61 and the outer ring 62 in the axial and radial directions is restricted. The multiple rolling elements 63 roll in the circumferential direction between the inner ring 61 and the outer ring 62. The cage 64 holds the multiple rolling elements 63 at approximately equal intervals in the circumferential direction.

[0053] The threaded shaft 51 is attached to the inner ring 61 by being press-fitted into the inner ring 61. Press-fitting is an example of an interference fit. The second outer peripheral surface 55b of the cylindrical wall 55 and the inner peripheral surface 61a of the inner ring 61 contact each other and are essentially joined to each other. Therefore, the bearing 35 and the threaded shaft 51 are restricted from moving relative to each other in the axial direction. Furthermore, the end surface 61b of the inner ring 61 contacts the flange 56 and is supported by the flange 56 in the axial direction.

[0054] The outer ring 62, the rolling elements 63, and the cage 64 are spaced apart from the screw shaft 51 and the gear 47. This allows the rolling elements 63 to roll smoothly between the inner ring 61 and the outer ring 62. Furthermore, the outer ring 62 can rotate smoothly around the central axis Axc relative to the screw shaft 51 and the inner ring 61.

[0055] 3, the cable end 36 is attached to the end 23b of the cable 23. The cable end 36 is spaced apart in the first axial direction Dx1 from the screw shaft 51. An end face 52a of the nut 52 faces the cable end 36.

[0056] The housing 31 has a lower case 71, an upper case 72, a plurality of fasteners 73 such as screws, and a motor bracket 74. The lower case 71 is an example of a case. The lower case 71 and the upper case 72 are each made of resin. However, the lower case 71 and the upper case 72 may be made of other materials. Furthermore, the resin lower case 71 and the upper case 72 may be joined to metal parts by, for example, insert molding.

[0057] The lower case 71 has two end faces 71a and 71b. The end face 71a is provided at an end of the lower case 71 in the first axial direction Dx1. The end face 71a is formed to be substantially flat and faces the first axial direction Dx1. The end face 71b is provided at an end of the lower case 71 in the second axial direction Dx2. The end face 71b is supported by the backing plate 12 directly or via a member such as a gasket.

[0058] Lower case 71 is provided with a through space 81, a recess 82, and a plurality of screw holes 83. Through space 81 is a hole that passes through lower case 71 along central axis Axc. Through space 81 is open to two end faces 71a, 71b.

[0059] The through space 81 has a plurality of portions that communicate with each other in the axial direction and that differ in size and shape. That is, the diameter of the through space 81 is not constant. In this embodiment, the through space 81 has four spaces 85, 86, 87, and 88. Each of the spaces 85, 86, 87, and 88 may also have a plurality of portions that differ in size and shape.

[0060] The space 85 opens to the end surface 71a of the lower case 71. The space 85 accommodates a part of the cable 23, the gear 47, a part of the nut 52, a part of the cylindrical wall 55 including the first outer peripheral surface 55a, and the flange 56.

[0061] Space 86 opens to end face 71b of lower case 71. Space 86 has a smaller diameter than space 85. Space 87 is located between spaces 85 and 86 and communicates with space 86. Space 87 has a smaller diameter than space 86. A portion of cable 23 is housed in each of spaces 86 and 87.

[0062] Space 88 is located between space 85 and space 87 and communicates with spaces 85 and 87. Space 88 has a smaller diameter than space 85 and a larger diameter than space 87. Space 88 accommodates a portion of cable 23, bearing 35, and a portion of cylindrical wall 55 including second outer peripheral surface 55b.

[0063] 4, lower case 71 further includes an inner circumferential surface 85a and a bottom surface 85b that define space 85, an inner circumferential surface 87a that defines space 87, and a first inner circumferential surface 88a, a second inner circumferential surface 88b, a sloped surface 88c, a support surface 88d, and a recessed surface 88e that define space 88. Second inner circumferential surface 88b is an example of an inner circumferential surface. Note that spaces 85, 87, and 88 may be defined by other surfaces.

[0064] The inner circumferential surface 85a, the inner circumferential surface 87a, the first inner circumferential surface 88a, and the second inner circumferential surface 88b are each formed in a generally cylindrical shape extending along the central axis Axc and facing radially inward. In other words, the inner circumferential surface 85a, the inner circumferential surface 87a, the first inner circumferential surface 88a, and the second inner circumferential surface 88b each face toward the central axis Axc.

[0065] A bottom surface 85b of the space 85 is connected to an end of the inner circumferential surface 85a in the second axial direction Dx2 and to the first inner circumferential surface 88a in the first axial direction Dx1. The bottom surface 85b is a flat surface that extends in a substantially annular shape in the circumferential direction and faces the first axial direction Dx1.

[0066] The second inner circumferential surface 88b is located axially between the first inner circumferential surface 88a and the inner circumferential surface 87a of the space 87. The second inner circumferential surface 88b has a smaller diameter than the first inner circumferential surface 88a. The second inner circumferential surface 88b is axially longer than the first inner circumferential surface 88a.

[0067] The inclined surface 88c is connected to an end of the first inner circumferential surface 88a in the second axial direction Dx2 and an end of the second inner circumferential surface 88b in the first axial direction Dx1. The inclined surface 88c is a substantially conical curved surface that tapers toward the second inner circumferential surface 88b. Note that the shape of the inclined surface 88c is not limited to a conical shape.

[0068] The support surface 88d is connected to an end of the second inner circumferential surface 88b in the second axial direction Dx2. The support surface 88d is a substantially annular plane extending in the circumferential direction and facing the first axial direction Dx1. The concave surface 88e is connected to an end of the support surface 88d on the radially inner side and to an end of the inner circumferential surface 87a in the first axial direction Dx1. The concave surface 88e is recessed from the support surface 88d in the second axial direction Dx2.

[0069] The outer ring 62 of the bearing 35 is attached to the lower case 71 by being press-fitted into the second inner peripheral surface 88b of the lower case 71. The outer peripheral surface 62a of the outer ring 62 and the second inner peripheral surface 88b of the lower case 71 contact each other and are essentially joined together. This restricts relative movement between the bearing 35 and the lower case 71 in the axial direction. Furthermore, the end face 62b of the outer ring 62 contacts the support surface 88d and is supported in the axial direction by the support surface 88d.

[0070] The inner ring 61, the rolling elements 63, and the cage 64 are spaced apart from the lower case 71. This allows the rolling elements 63 to roll smoothly between the inner ring 61 and the outer ring 62. Furthermore, the inner ring 61 can rotate smoothly about the central axis Axc relative to the outer ring 62 and the lower case 71. As a result, the bearing 35 supports the screw shaft 51 rotatably about the central axis Axc relative to the lower case 71.

[0071] 3, the recess 82 is recessed from the end face 71a. In other words, the recess 82 opens to the end face 71a. Furthermore, the recess 82 communicates with a space 85 in the radial direction. The gears 45, 46 and the support shaft 48 are housed in the recess 82. The end of the support shaft 48 in the second axial direction Dx2 is held by the lower case 71 in the recess 82.

[0072] The plurality of screw holes 83 are spaced apart from the through space 81 and the recess 82 and open to the end face 71a. A metal cylinder may be joined to the inside of the screw hole 83 by insert molding, for example.

[0073] The upper case 72 has a flange 91, a motor cover 92, and a mechanism cover 93. However, the upper case 72 is not limited to this example.

[0074] The flange 91 has an end surface 91a. The end surface 91a is provided at an end of the flange 91 in the second axial direction Dx2. The end surface 91a is formed to be substantially flat and faces the second axial direction Dx2.

[0075] An end surface 91a of the flange 91 faces an end surface 71a of the lower case 71. The flange 91 is supported on the end surface 71a of the lower case 71 directly or via a member such as a gasket.

[0076] A plurality of insertion holes 95 are provided in the flange 91. The insertion holes 95 pass through the flange 91 and open to an end face 91a. A metal cylinder may be joined to the inside of the insertion holes 95 by, for example, insert molding.

[0077] The insertion holes 95 of the flange 91 communicate with the screw holes 83 of the lower case 71. The multiple fasteners 73 pass through the insertion holes 95 and are fitted into the screw holes 83. In this way, the fasteners 73 attach the upper case 72 to the lower case 71.

[0078] The motor cover 92 protrudes from the flange 91 in the first axial direction Dx1. The motor cover 92 defines a motor chamber 97. The motor chamber 97 is recessed from the end surface 91a of the flange 91 in the first axial direction Dx1. The motor 32 is disposed in the motor chamber 97. That is, the upper case 72 at least partially accommodates the motor 32.

[0079] The motor bracket 74 is attached to the motor cover 92 so as to cover the motor chamber 97. The motor bracket 74 holds the motor 32 in the motor chamber 97. The motor bracket 74 also holds the end of the support shaft 48 in the first axial direction Dx1.

[0080] The mechanism cover 93 protrudes from the flange 91 in the first axial direction Dx1. The mechanism cover 93 defines a mechanism chamber 98 and a cable end chamber 99. The mechanism chamber 98 is recessed in the first axial direction Dx1 from the end face 91a of the flange 91. The cable end chamber 99 communicates with the end of the mechanism chamber 98 in the first axial direction Dx1.

[0081] A part of the cable 23, a part of the nut 52, and a part of the cylindrical wall 55 are disposed in the mechanism compartment 98. That is, the upper case 72 accommodates the screw shaft 51 and the nut 52 at least partially.

[0082] The end 23b of the cable 23 and the cable end 36 are disposed in the cable end chamber 99. In the axial direction, the cable end chamber 99 is longer than the cable end 36. In the cable end chamber 99, the cable end 36 can move in the axial direction.

[0083] The MGU 15 moves the brake shoe 11 via the movement mechanism 17, for example, as follows: For example, in a released state in which the MGU 15 is not moving the brake shoe 11, the nut 52 is spaced apart from the cable end 36 in the second axial direction Dx2.

[0084] In the released state, the nut 52 does not apply tension to the cable 23, and the cable 23 is loose. In other words, the MGU 15 does not pull the cable 23. As a result, the spring 16 separates the brake shoe 11 from the drum rotor 3. Note that in the released state, the nut 52 may be in contact with the cable end 36, and the cable 23 may be under tension.

[0085] When the motor 32 drives the screw shaft 51 to rotate around the central axis Axc, the nut 52 attached to the screw shaft 51 is also driven around the central axis Axc. However, the housing 31 restricts the rotation of the nut 52.

[0086] The male thread 55c of the rotating screw shaft 51 axially presses the female thread 52c of the nut 52, the rotation of which is restricted. Therefore, when the screw shaft 51 rotates around the central axis Axc, the nut 52 moves in the axial direction in response to the rotation of the screw shaft 51.

[0087] For example, when the motor 32 rotates the screw shaft 51 in one direction around the central axis Axc, the screw shaft 51 moves the nut 52 in the first axial direction Dx1. When the nut 52 moves in the first axial direction Dx1, the end face 52a of the nut 52 comes into contact with the cable end 36.

[0088] The cable end 36 is supported by the end surface 52a of the nut 52. That is, the cable 23 is supported by the nut 52 via the cable end 36. The nut 52 moves in the first axial direction Dx1, thereby moving the cable 23 in the first axial direction Dx1 via the cable end 36. In other words, the nut 52 pulls the cable 23 in the first axial direction Dx1.

[0089] The cable 23, pulled by the nut 52, pulls the lever 21. When the lever 21 is pulled by the cable 23, it pushes the brake shoe 11R via the strut 24. This causes the brake shoe 11R to rotate around the end 11a and press the lining 11c against the inner circumferential surface 3a of the drum rotor 3.

[0090] Furthermore, when the lever 21 rotates around the strut 24 as a fulcrum, the lever 21 presses the brake shoe 11L via the pin 22. As a result, the brake shoe 11L rotates around the end 11a and presses the lining 11c against the inner peripheral surface 3a of the drum rotor 3.

[0091] As described above, the movement mechanism 17 is moved by the tension of the cable 23 pulled by the nut 52, thereby bringing the brake shoes 11R, 11L into contact with the drum rotor 3. In the apply state in which the MGU 15 moves the brake shoes 11 using the movement mechanism 17, the brake shoes 11R, 11L press the linings 11c against the inner circumferential surface 3a of the drum rotor 3. As a result, the brake shoes 11R, 11L apply the brakes to the drum rotor 3 and the wheel 2.

[0092] When the motor 32 rotates the screw shaft 51 in the reverse direction around the central axis Axc, the screw shaft 51 moves the nut 52 in the second axial direction Dx2. When the nut 52 moves in the second axial direction Dx2, for example, a spring pulling the cable 23 moves the cable 23 in the second axial direction Dx2. In other words, the nut 52 sends out the cable 23 in the second axial direction Dx2 while remaining in contact with the cable 23.

[0093] As the nut 52 feeds out the cable 23, the tension on the cable 23 decreases and is eventually released, i.e., the cable 23 returns to a relaxed, released state, and the spring 16 moves the brake shoe 11 away from the drum rotor 3.

[0094] In the applied state, the tension of the cable 23 pulls the screw shaft 51 in the second axial direction Dx2 via the cable end 36 and the nut 52. The lower case 71 supports the screw shaft 51 via the bearing 35.

[0095] For example, the second inner peripheral surface 88b of the lower case 71 is substantially joined by press fitting to the outer peripheral surface 62a of the outer ring 62. Furthermore, the support surface 88d of the lower case 71 supports the end face 62b of the outer ring 62. Therefore, the lower case 71 supports the outer ring 62 so as to restrict movement of the outer ring 62 in the second axial direction Dx2.

[0096] The rolling elements 63 are fitted in the raceways of the inner ring 61 and the outer ring 62. Therefore, the outer ring 62 supports the inner ring 61 via the rolling elements 63 so as to restrict movement of the inner ring 61 in the second axial direction Dx2.

[0097] An inner peripheral surface 61a of the inner ring 61 is substantially joined by press fitting to the second outer peripheral surface 55b of the screw shaft 51. Furthermore, an end face 61b of the inner ring 61 supports the flange 56 of the screw shaft 51. Therefore, the inner ring 61 supports the screw shaft 51 so as to restrict movement of the screw shaft 51 in the second axial direction Dx2.

[0098] As described above, the tension of the cable 23 pulls the screw shaft 51 in the second axial direction Dx2 via the nut 52, and the lower case 71 supports the screw shaft 51 via the bearing 35. Therefore, the screw shaft 51 is held in the axial direction by the tension of the cable 23 in the lower case 71.

[0099] The electric brake device 10 of this embodiment is an electric parking brake in which the cable 23 is pulled by the MGU 15 when the vehicle 1 is parked. Therefore, the load acting in the axial direction on the bearing 35 is lower overall compared to when the MGU 15 pulls the cable 23 to generate a braking force as a service brake. Therefore, even if an axial load acts on the bearing 35, which is a radial ball bearing, the electric brake device 10 can prevent deformation of the bearing 35. Note that the electric brake device 10 may also pull the cable 23 for the service brake.

[0100] On the other hand, in the released state, the cable end 36 is separated from the nut 52. Therefore, the tension of the cable 23 does not hold the screw shaft 51. However, as described above, the inner ring 61 is substantially joined to the screw shaft 51, and the outer ring 62 is substantially joined to the lower case 71. Therefore, even in the released state, the screw shaft 51 is held in the axial direction by the lower case 71. Note that in the released state, the nut 52 may be in contact with the cable end 36.

[0101] The bearing 35 restricts axial movement of the screw shaft 51 relative to the lower case 71. Therefore, the electric brake device 10 can suppress the generation of abnormal noise caused by the screw shaft 51 or the gear 47 colliding with the lower case 71 during vibration, for example.

[0102] Hereinafter, a part of the method for manufacturing the electric brake device 10 will be illustrated with reference to Fig. 5. Note that the method for manufacturing the electric brake device 10 is not limited to the method described below, and other methods may also be used. Fig. 5 is a cross-sectional view showing the bearing 35, the threaded shaft 51, and the lower case 71 during assembly of this embodiment. As shown in Fig. 5, first, the threaded shaft 51 is press-fitted into the inner ring 61.

[0103] For example, the screw shaft 51 is press-fitted into the inner ring 61 held by a jig. The screw shaft 51 is press-fitted into the inner ring 61 before being accommodated in the housing 31. This makes it easy to arrange the jig and to handle the screw shaft 51.

[0104] Before press-fitting, the second outer peripheral surface 55b of the cylindrical wall 55 of the screw shaft 51 has a larger diameter than the inner peripheral surface 61a of the inner ring 61. When the screw shaft 51 is press-fitted into the inner ring 61, the second outer peripheral surface 55b and the inner peripheral surface 61a are substantially joined together.

[0105] After the threaded shaft 51 is press-fitted into the inner ring 61, the outer ring 62 is press-fitted into the lower case 71. For example, a sub-assembly including the bearing 35 and the threaded shaft 51 is inserted into a space 88 through a space 85 that opens to an end face 71 a of the lower case 71.

[0106] The outer peripheral surface 62a of the outer ring 62 has a smaller diameter than both the inner peripheral surface 85a and the first inner peripheral surface 88a of the lower case 71. Therefore, the outer ring 62 passes through the space 85 and is smoothly inserted inside the first inner peripheral surface 88a.

[0107] Before press-fitting, the outer peripheral surface 62a of the outer ring 62 has a larger diameter than the second inner peripheral surface 88b of the lower case 71. The inclined surface 88c tapers from the first inner peripheral surface 88a to the second inner peripheral surface 88b. Therefore, the outer ring 62 abuts against the inclined surface 88c and is press-fitted into the second inner peripheral surface 88b while being guided by the inclined surface 88c. When the outer ring 62 is press-fitted into the lower case 71, the outer peripheral surface 62a and the second inner peripheral surface 88b are substantially joined together.

[0108] The threaded shaft 51, the inner ring 61, and the outer ring 62 are metal components. On the other hand, the lower case 71 is a resin component. Therefore, the press-fitting force when the outer ring 62 is press-fitted into the lower case 71 is lower than the press-fitting force when the threaded shaft 51 is press-fitted into the inner ring 61. Therefore, the outer ring 62 can be easily press-fitted into the lower case 71.

[0109] In the above example, the threaded shaft 51 is press-fitted into the inner ring 61, and the outer ring 62 is press-fitted into the lower case 71. However, the method is not limited to press-fitting, and the threaded shaft 51 may be fitted into the inner ring 61 and the outer ring 62 may be fitted into the lower case 71 by other interference fits such as shrink fitting or cold fitting.

[0110] In the electric brake device 10 according to the present embodiment described above, the movement mechanism 17 has the cable 23 and is configured to be moved by the tension of the cable 23 to bring the brake shoe 11 into contact with the drum rotor 3. The nut 52 is attached to the threaded shaft 51 and is configured to pull the cable 23 by moving in the axial direction along the central axis Axc in response to rotation of the threaded shaft 51 about the central axis Axc. The lower case 71 accommodates at least a portion of the threaded shaft 51. The bearing 35 has an inner ring 61, an outer ring 62, and rolling elements 63. The threaded shaft 51 is interference-fitted into the inner ring 61. The outer ring 62 is interference-fitted into the lower case 71.

[0111] Therefore, as an example, when the nut 52 pulls the cable 23, the threaded shaft 51 is pulled by the tension of the cable 23 via the nut 52 and is held in the axial direction by the lower case 71. On the other hand, when the nut 52 does not pull the cable 23, the tension does not hold the threaded shaft 51. However, because the inner ring 61 is interference-fitted to the threaded shaft 51 and the outer ring 62 is interference-fitted to the lower case 71, the bearing 35 limits relative axial movement between the threaded shaft 51 and the lower case 71. Therefore, the electric brake device 10 can prevent the threaded shaft 51 from moving axially with respect to the lower case 71, and can suppress the generation of abnormal noise due to relative movement between the threaded shaft 51 and the lower case 71. Furthermore, because a thrust bearing that bears an axial load or other components that limit axial movement of a rotating member are not required, the electric brake device 10 can reduce the number of parts.

[0112] The rolling elements 63 are balls. Therefore, as an example, the bearing 35 (ball bearing) has a larger axial load tolerance than a case in which the rolling elements 63 are rollers. Also, the range of relative axial movement between the inner ring 61 and the outer ring 62 is small. Therefore, the electric brake device 10 can prevent the threaded shaft 51 from moving axially relative to the lower case 71, and can suppress the generation of abnormal noise.

[0113] The lower case 71 has a second inner circumferential surface 88b and a sloped surface 88c. The second inner circumferential surface 88b faces the central axis Axc. The sloped surface 88c is connected to an end of the second inner circumferential surface 88b in the axial direction and tapers toward the second inner circumferential surface 88b. The outer ring 62 is interference-fitted to the second inner circumferential surface 88b. Therefore, as an example, the outer ring 62 can be guided by the sloped surface 88c and interference-fitted to the second inner circumferential surface 88b. This makes it easy to assemble the electric brake device 10.

[0114] The threaded shaft 51 is made of metal. The lower case 71 is made of resin. The threaded shaft 51 is press-fitted into the inner ring 61. The outer ring 62 is press-fitted into the lower case 71 after the threaded shaft 51 is press-fitted into the inner ring 61. Therefore, for example, the press-fitting force of the bearing 35 into the threaded shaft 51 and the lower case 71 can be reduced compared to when both the threaded shaft 51 and the lower case 71 are made of metal. Therefore, the manufacturing method of the electric brake device 10 can prevent the bearing 35 from being deformed by the press-fitting force when the outer ring 62 is press-fitted into the lower case 71. Furthermore, the metal threaded shaft 51, which generates a larger press-fitting force, can be press-fitted into the inner ring 61 first outside the lower case 71. Therefore, the manufacturing method of the electric brake device 10 can easily align the threaded shaft 51 and the inner ring 61, and therefore easily press-fit the threaded shaft 51 into the inner ring 61. Furthermore, the manufacturing method of the electric brake device 10 allows the outer ring 62 to be easily press-fitted into the resin lower case 71 with a small press-fitting force.

[0115]

[0010] At least one embodiment of the electric brake device described above includes, as an example, a braking member configured to brake a wheel by contacting a drum rotor that rotates integrally with the wheel, a moving mechanism having a cable and configured to bring the braking member into contact with the drum rotor by being moved by tension in the cable, a rotating member, a motor that drives the rotating member to rotate about a rotation axis, a linear motion member attached to the rotating member and configured to pull the cable by moving in an axial direction along the rotation axis in response to rotation of the rotating member about the rotation axis, a case that accommodates at least a portion of the rotating member, and a rolling bearing that includes an inner ring in which the rotating member is shrink-fitted, an outer ring that is shrink-fitted in the case, and rolling elements that roll between the inner ring and the outer ring, and that supports the rotating member rotatably about the rotation axis relative to the case. Thus, as an example, when the linear motion member pulls the cable, the rotating member is pulled by the tension in the cable via the linear motion member and is held axially by the case. On the other hand, when the linear motion member is not pulling the cable, tension does not hold the rotating member. However, because the inner ring is interference-fitted to the rotating member and the outer ring is interference-fitted to the case, the rolling bearing limits relative axial movement between the rotating member and the case. Therefore, the electric brake device can limit axial movement of the rotating member relative to the case, thereby suppressing the generation of abnormal noise due to relative movement between the rotating member and the case. Furthermore, because there is no need for a thrust bearing that supports axial loads or other components that limit axial movement of the rotating member, the electric brake device can reduce the number of parts.

[0116] In the electric brake device, as an example, the rolling elements are balls. Therefore, as an example, rolling bearings (ball bearings) have a larger axial load capacity than rolling elements that are rollers. Also, the range of relative axial movement between the inner ring and the outer ring is small. Therefore, the electric brake device can prevent the rotating member from moving axially relative to the case, thereby suppressing the generation of abnormal noise.

[0117] In the electric brake device, as one example, the case has an inner circumferential surface facing the rotation shaft and an inclined surface that is connected to an end of the inner circumferential surface in the axial direction and tapers toward the inner circumferential surface, and the outer ring is interference-fitted to the inner circumferential surface. Thus, as one example, the outer ring can be interference-fitted to the inner circumferential surface while being guided by the inclined surface. This makes the electric brake device easy to assemble.

[0118] As an example, a manufacturing method of an electric brake device according to at least one embodiment described above is a manufacturing method of an electric brake device including: a braking member configured to brake a wheel by contacting a drum rotor that rotates integrally with the wheel; a moving mechanism having a cable and configured to be moved by the tension of the cable to bring the braking member into contact with the drum rotor; a rotating member; a motor that drives the rotating member to rotate about a rotation axis; a linear-motion member attached to the rotating member and configured to pull the cable by moving in the axial direction along the rotation axis in response to the rotation of the rotating member about the rotation axis; a case that houses at least a portion of the rotating member; and a rolling bearing that has an inner ring attached to the rotating member, an outer ring attached to the case, and rolling elements that roll between the inner ring and the outer ring, and that supports the rotating member rotatably about the rotation axis relative to the case, the method including: interference-fitting the rotating member into the inner ring; and interference-fitting the outer ring into the case. Therefore, as an example, when the linear moving member pulls the cable, the rotating member is pulled by the tension of the cable via the linear moving member and is held axially to the case. On the other hand, when the linear moving member does not pull the cable, the tension does not hold the rotating member. However, because the inner ring is interference-fitted to the rotating member and the outer ring is interference-fitted to the case, the rolling bearing limits relative axial movement between the rotating member and the case. Therefore, the manufacturing method for an electric brake device can prevent axial movement of the rotating member relative to the case, and can suppress the generation of abnormal noise due to relative movement between the rotating member and the case. Furthermore, because a thrust bearing that bears axial loads and other components that limit axial movement of the rotating member are not required, this manufacturing method can reduce the number of parts in the electric brake device.

[0119] In the above-described manufacturing method for an electric brake device, as an example, the rotating member is made of metal, the case is made of resin, the rotating member is press-fitted into the inner ring, and the outer ring is press-fitted into the case after the rotating member is press-fitted into the inner ring. Therefore, as an example, the rolling bearing can reduce the press-fit force when press-fitting the rotating member and the case compared to when both the rotating member and the case are made of metal. Therefore, the manufacturing method for an electric brake device can prevent the rolling bearing from being deformed by the press-fit force when press-fitting the outer ring into the case. Furthermore, the press-fitting of the metal rotating member into the inner ring, which requires a larger press-fit force, can be performed first outside the case. Therefore, the manufacturing method for an electric brake device can easily align the rotating member and the inner ring, thereby easily press-fitting the rotating member into the inner ring. Furthermore, the manufacturing method for an electric brake device can easily press-fit the outer ring into the resin case with a small press-fit force.

[0120] While the embodiments of the present invention have been described above, the above-described embodiments and modifications are merely examples and are not intended to limit the scope of the invention. The above-described embodiments and modifications can be implemented in various other forms, and various omissions, substitutions, combinations, and modifications can be made without departing from the spirit of the invention. Furthermore, the configurations and shapes of each embodiment and each modification can be partially interchanged. [Explanation of symbols]

[0121] 2...wheel, 3...drum rotor, 10...electric brake device, 11, 11L, 11R...brake shoe (braking member), 17...movement mechanism, 23...cable, 32...motor, 35...bearing (rolling bearing), 51...screw shaft (rotating member), 52...nut (linear member), 61...inner ring, 62...outer ring, 63...rolling element, 71...lower case (case), 88b...second inner surface (inner surface), 88c...inclined surface, Axc...central axis (rotating axis).

Claims

1. a braking member configured to brake the wheel by contacting a drum rotor that rotates integrally with the wheel; a moving mechanism having a cable and configured to be moved by tension in the cable to bring the braking member into contact with the drum rotor; A rotating member; a motor that drives the rotary member to rotate about a rotation axis; a linear motion member attached to the rotating member and configured to move in an axial direction along the rotation axis in response to rotation of the rotating member about the rotation axis, thereby pulling the cable; a case that accommodates at least a portion of the rotating member; a rolling bearing including an inner ring in which the rotating member is interference-fitted, an outer ring in which the case is interference-fitted, and rolling elements that roll between the inner ring and the outer ring, and which supports the rotating member rotatably around the rotation axis relative to the case; An electric brake device comprising:

2. The rolling elements are balls. The electric brake device according to claim 1.

3. the case has an inner circumferential surface facing the rotation axis, and an inclined surface that is connected to an end of the inner circumferential surface in the axial direction and tapers toward the inner circumferential surface, The outer ring is interference-fitted onto the inner peripheral surface.

3. The electric brake device according to claim 1 or 2.

4. a braking member configured to brake the wheel by contacting a drum rotor that rotates integrally with the wheel; a moving mechanism having a cable and configured to be moved by tension in the cable to bring the braking member into contact with the drum rotor; A rotating member; a motor that drives the rotary member to rotate about a rotation axis; a linear motion member attached to the rotating member and configured to move in an axial direction along the rotation axis in response to rotation of the rotating member about the rotation axis, thereby pulling the cable; a case that accommodates at least a portion of the rotating member; a rolling bearing including an inner ring attached to the rotating member, an outer ring attached to the case, and rolling elements that roll between the inner ring and the outer ring, and supporting the rotating member rotatably around the rotation axis relative to the case; A manufacturing method of an electric brake device comprising: interference-fitting the rotating member into the inner ring; interference-fitting the outer ring into the case; A method for manufacturing an electric brake device comprising:

5. the rotating member is made of metal, The aforementioned case is made of resin, the rotating member is press-fitted into the inner ring, the outer ring is press-fitted into the case after the rotating member is press-fitted into the inner ring; A method for manufacturing the electric brake device according to claim 4.

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