Braking device

Abstract

A braking device according to an embodiment of the present invention comprises, as an example: a backing plate; a braking member that is configured to brake a wheel by contacting a drum rotor and is supported by the backing plate; a rotation member that is capable of rotating about a central shaft; a linear motion member that is attached to the rotation member so as to move in the shaft direction in accordance with the rotation of the rotation member; a cable that is supported by the linear motion member and configured to cause the braking member to contact the drum rotor by being pulled by the linear motion member; and a first case that includes a support surface attached to the backing plate and supporting the rotation member, a first portion made from a metal, the first portion being provided between the support surface and the backing plate and surrounding the cable, and a second portion made from a resin, the second portion being formed integrally with the first portion and at least partially accommodating the rotation member.

Description

braking device

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to a braking device.

[0002] A braking device including a unit that moves a brake shoe by pulling a cable is known. The unit includes, for example, a motor, a mechanism that converts the rotation of the motor into linear motion to pull the cable, and a case that houses the motor and the mechanism (see Patent Document 1).

[0003] JP 2017-83010 A

[0004] However, in the conventional configuration, the entire unit case is made of metal, which makes the braking device heavy. On the other hand, since the case receives reaction force from the pulled cable, it is difficult to make the entire case out of resin.

[0005] Therefore, the present invention has been made in view of the above, and provides a braking device that can be made lighter.

[0006] A braking device according to an embodiment of the present invention includes, as an example, a backing plate, a braking member configured to brake a wheel by contacting a drum rotor that rotates integrally with the wheel and supported by the backing plate, a rotating member rotatable about a central axis, a linearly-acting member attached to the rotating member so as to move axially along the central axis in response to rotation of the rotating member, a cable supported by the linearly-acting member and configured to contact the braking member with the drum rotor when pulled by the linearly-acting member, and a first case including: a support surface attached to the backing plate and supporting the rotating member, a metal first portion disposed between the support surface and the backing plate and surrounding the cable, and a resin second portion formed integrally with the first portion and at least partially housing the rotating member. Thus, as an example, when the linearly-acting member pulls the cable, a reaction force of the cable acts on the support surface via the linearly-acting member and the rotating member. The first case has a first metal portion between the support surface and the backing plate, which provides the strength to withstand the reaction force. Meanwhile, the first case has a second resin portion that houses the rotating member, which is less susceptible to the reaction force. Resin generally has a lower density than metal. This allows the braking device to be lighter than if the entire first case were made of metal.

[0007] Fig. 1 is a side view showing a braking device according to one embodiment, Fig. 2 is a rear view showing the braking device of the embodiment, and Fig. 3 is a cross-sectional view showing an MGU of the embodiment.

[0008] An embodiment will be described below with reference to FIGS. 1 to 3. Note that 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.

[0009] 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.

[0010] Fig. 1 is a side view showing a braking device 10 according to this embodiment. Fig. 2 is a rear view showing the braking device 10 according to this embodiment. As shown in Fig. 2, the braking device 10 is a drum brake mounted on a vehicle 1 such as an automobile.

[0011] The braking device 10 is disposed inside the cylindrical peripheral wall 2a of the wheel 2. The braking device 10 may be disposed inside either a driving wheel or a non-driving wheel 2. However, the braking device 10 is not limited to this example.

[0012] 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 braking device 10. The Y-axis is provided along the thickness of the braking device 10. The Z-axis is provided along the height of the braking device 10. The X-axis extends substantially in the fore-and-aft direction of the vehicle 1. Furthermore, the Y-axis extends substantially in the width direction (vehicle width direction) of the vehicle 1.

[0013] 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).

[0014] 1, the braking 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 moving mechanism 17. The brake shoes 11 are an example of a braking member.

[0015] The two brake shoes 11 are spaced apart from each other in the X direction and 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.

[0016] 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.

[0017] 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 via, for example, a part of the suspension. The backing plate 12 supports various elements of the braking device 10.

[0018] 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.

[0019] 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.

[0020] Each of the two brake shoes 11 has a strip-shaped lining 11c. The braking 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. As a result, friction between the lining 11c and the inner circumferential surface 3a of the drum rotor 3 brakes the drum rotor 3 and the wheel 2. In other words, the brake shoes 11 brake the wheel 2 by coming into contact with the drum rotor 3, which rotates integrally with the wheel 2.

[0021] For example, the braking 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 braking device 10 moves the brake shoes 11 using the MGU 15. In other words, the braking 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.

[0022] The wheel cylinders 14 press the ends 11b of the brake shoes 11 in response to hydraulic pressure. This causes the two brake shoes 11 to rotate around the ends 11a, and the ends 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.

[0023] 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 3 a of the drum rotor 3.

[0024] 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, a strut 24, and a pipe member 25.

[0025] 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 around the pin 22.

[0026] 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.

[0027] 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.

[0028] The pipe member 25 surrounds a portion of the cable 23. In this way, the pipe member 25 protects and guides the cable 23. The pipe member 25 is made of, for example, metal, and maintains a shape that guides the cable 23.

[0029] When the MGU 15 pulls the lever 21 via the cable 23, the lever 21 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 peripheral surface 3a of the drum rotor 3.

[0030] 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 portion 11a and presses the lining 11c against the inner peripheral surface 3a of the drum rotor 3. The brake shoes 11R, 11L press the lining 11c against the inner peripheral surface 3a of the drum rotor 3, thereby braking the drum rotor 3 and the wheel 2.

[0031] 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, a cable end 36, a guide member 37, and a pipe seal 38. The pipe seal 38 is an example of a sealing member.

[0032] The housing 31 accommodates the other end 23b of the cable 23, the motor 32, the reduction mechanism 33, the motion conversion mechanism 34, the bearings 35, the cable end 36, the guide member 37, and the pipe seal 38. The housing 31 is attached to the backing plate 12, for example, by bolts.

[0033] 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.

[0034] 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.

[0035] The motion converting mechanism 34 has a rotating member 51 and a linear moving member 52. The rotating member 51 and the linear moving member 52 are each formed in a substantially cylindrical shape extending along a central axis Axc. The central axis Axc is, for example, the central axis of the rotating member 51 and the linear moving member 52. Note that the rotating member 51 and the linear moving member 52 are not limited to this example.

[0036] For convenience, the terms axial, radial, and circumferential are defined herein. The axial direction is a direction along the central axis Axc. The axial direction includes a first axial direction Dx1 that is a 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 a direction perpendicular to the central axis Axc. The circumferential direction is a direction around the central axis Axc.

[0037] The rotating member 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 extending radially outward from the cylindrical wall 55. The gear 47 of the reduction mechanism 33 is provided on the radially outer end of the flange 56.

[0038] Gear 47 provided on flange 56 can transmit rotation between output shaft 41 and gear 47 via a plurality of other gears 45, 46 included in speed reduction mechanism 33. Therefore, the rotation of output shaft 41 is transmitted to rotating member 51 via speed reduction mechanism 33. Rotating member 51 rotates around central axis Axc in conjunction with output shaft 41.

[0039] The cylindrical wall 55 has a first outer peripheral surface 55a, a second outer peripheral surface 55b, and a male 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. The first outer peripheral surface 55a extends from the flange 56 in the first axial direction Dx1. The second outer peripheral surface 55b extends from the flange 56 in the second axial direction Dx2. In other words, the second outer peripheral surface 55b is spaced from the first outer peripheral surface 55a in the second axial direction Dx2. The male thread 55c is provided on the second outer peripheral surface 55b.

[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 linear motion member 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 linear motion member 52 is supported by the housing 31 so as to be restricted in rotation about the central axis Axc and to be movable in the axial direction. The linear motion member 52 has an end surface 52a, an inner peripheral surface 52b, and a female thread 52c.

[0042] The end surface 52a is provided at an end of the linear motion member 52 in the first axial direction Dx1. The inner circumferential surface 52b is a substantially cylindrical curved surface extending along the central axis Axc and facing radially inward. 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 linear motion member 52 to the rotating member 51. Note that the rotating member 51 may be formed with a female thread, and the linear motion member 52 may be formed with a male thread.

[0043] The bearing 35 is, for example, a ball bearing. The bearing 35 can withstand not only radial loads but also axial loads. The bearing 35 may be another type of bearing, such as a roller bearing or a bushing, or may be a thrust bearing. The bearing 35 has an inner race 61, an outer race 62, and a plurality of balls 63.

[0044] The inner race 61 and the outer race 62 are formed in a generally cylindrical shape extending along the central axis Axc. The inner race 61 is attached to the second outer peripheral surface 55b of the cylindrical wall 55 and is supported by the flange 56. The outer race 62 surrounds the inner race 61 and is supported by the housing 31. A plurality of balls 63 are positioned between the inner race 61 and the outer race 62 and are aligned in the circumferential direction. As a result, the rotating member 51 is supported by the housing 31 via the bearing 35 so as to be rotatable about the central axis Axc.

[0045] The cable end 36 is attached to the end 23b of the cable 23. The cable end 36 is supported by the end surface 52a of the linear motion member 52. That is, the cable 23 is supported by the linear motion member 52 via the cable end 36. Note that the cable end 36 may be temporarily supported by the housing 31, for example.

[0046] When supporting the cable end 36, the linear motion member 52 can move the cable 23 in the axial direction via the cable end 36. In other words, the linear motion member 52 can pull or feed the cable 23.

[0047] The cable 23 is biased in the second axial direction Dx2 by, for example, a spring. As a result, even if the cable 23 moves in the axial direction, the cable end 36 continues to contact the linear motion member 52, and tension is always generated in the cable 23.

[0048] When the rotation of the output shaft 41 is transmitted to the rotating member 51 via the speed reducer 33, the rotating member 51 rotates around the central axis Axc. Since the female thread 52c and the male thread 55c are engaged with each other, the linear motion member 52 moves in the axial direction in response to the rotation of the rotating member 51.

[0049] For example, when the output shaft 41 rotates in one direction, the rotating member 51 rotates to move the linear moving member 52 in the first axial direction Dx1. When the end face 52a supports the cable end 36, the linear moving member 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 linear moving member 52 pulls the cable 23 in the first axial direction Dx1. The cable 23 pulled by the linear moving member 52 pulls the lever 21, causing the brake shoes 11R, 11L to contact the drum rotor 3.

[0050] As the output shaft 41 rotates in the reverse direction, the rotating member 51 rotates to move the linearly-acting member 52 in the second axial direction Dx2. When the linearly-acting member 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. This releases the tensile force that the cable 23 applies to the lever 21, and the brake shoes 11R, 11L move away from the drum rotor 3.

[0051] Guide member 37 is made of, for example, synthetic resin. Guide member 37 is attached to housing 31 at a position spaced apart from cylindrical wall 55 in second axial direction Dx2. Guide member 37 is formed in a generally cylindrical shape surrounding central axis Axc. Guide member 37 guides cable 23 moving in the axial direction.

[0052] The pipe seal 38 is, for example, a substantially annular rubber seal. The pipe seal 38 is interposed between the pipe member 25 and the housing 31. The pipe seal 38 seals the gap between the pipe member 25 and the housing 31, and restricts, for example, liquid from entering the inside of the housing 31.

[0053] The housing 31 includes a lower case 71, an upper case 72, and a plurality of fasteners 73 such as screws. The lower case 71 is an example of a first case. The upper case 72 is an example of a second case.

[0054] The lower case 71 has a metal portion 81, a plurality of nuts 82, and a resin portion 83. The metal portion 81 is an example of a first portion and may also be referred to as a sleeve. The resin portion 83 is an example of a second portion. The metal portion 81, the nuts 82, and the resin portion 83 are integrally formed by, for example, insert molding.

[0055] The metal portion 81 and the nut 82 are each a metal member. The material of the metal portion 81 is, for example, cast iron, stainless steel, or aluminum alloy. The material of the nut 82 is, for example, stainless steel. However, the material of the metal portion 81 and the nut 82 may be other metals.

[0056] The metal portion 81 has a cylindrical portion 91, a flange portion 92, and a plurality of nut portions 93. The cylindrical portion 91, the flange portion 92, and the nut portions 93 are integrally formed by, for example, die-casting or welding. However, the cylindrical portion 91, the flange portions 92, and the nut portions 93 are not limited to this example.

[0057] The tubular portion 91 is formed in a generally cylindrical shape extending along the central axis Axc. That is, the tubular portion 91 is provided with a through-hole 95 that penetrates the tubular portion 91 along the central axis Axc. The through-hole 95 penetrates the metal portion 81 and opens to the outside of the metal portion 81.

[0058] The cylindrical portion 91 has an inner circumferential surface 91a and an outer circumferential surface 91b. The inner circumferential surface 91a and the outer circumferential surface 91b are each a substantially cylindrical curved surface extending along the central axis Axc. The inner circumferential surface 91a faces inward of the cylindrical portion 91 and forms (defines, defines) the through-hole 95. In other words, the inner circumferential surface 91a faces the central axis Axc. The outer circumferential surface 91b is located on the opposite side of the inner circumferential surface 91a and faces radially outward.

[0059] The flange portion 92 protrudes radially outward from the outer circumferential surface 91b at the end of the cylindrical portion 91 in the second axial direction Dx2. The flange portion 92 is provided at the end of the lower case 71 in the second axial direction Dx2.

[0060] The flange portion 92 has a connection surface 92a. The connection surface 92a contacts the backing plate 12. A sealant may be interposed between the connection surface 92a and the backing plate 12. The flange portion 92 also has a plurality of insertion holes 96. The insertion holes 96 penetrate the flange portion 92 and open to the connection surface 92a.

[0061] The plurality of nut portions 93 are attached to the flange portion 92. For example, the nut portions 93 are attached to the surface of the flange portion 92 opposite the connection surface 92 a. A screw hole 97 is provided in each of the plurality of nut portions 93. The screw hole 97 communicates with the corresponding insertion hole 96. The nut portion 93 has a female thread provided in the screw hole 97.

[0062] For example, a bolt passes through the backing plate 12, passes through the insertion hole 96, and is screwed into the screw hole 97. In this way, the lower case 71 is attached to the backing plate 12. However, the lower case 71 may be attached to the backing plate 12 by other methods.

[0063] The metal portion 81 has an outer surface 81a. The outer surface 81a is the surface of the metal portion 81 that faces the outside of the braking device 10. For example, an outer peripheral surface 91b of the cylindrical portion 91 faces the outside of the braking device 10 and is included in the outer surface 81a.

[0064] On the other hand, the connection surface 92a of the flange portion 92 comes into contact with the backing plate 12 and is covered by the backing plate 12, and therefore does not face the outside of the braking device 10. For this reason, the connection surface 92a is not included in the outer surface 81a. Furthermore, the inner surface of the flange portion 92 that forms the insertion hole 96 faces the inside of the insertion hole 96 and is covered by the bolt, and therefore is not included in the outer surface 81a. Of the flange portion 92, the surface opposite the connection surface 92a and the edge of the flange portion 92 face the outside of the braking device 10 and are included in the outer surface 81a.

[0065] The inner surface of the nut portion 93 that forms the screw hole 97 faces the inside of the screw hole 97 and is covered by the bolt, and is therefore not included in the outer surface 81 a. The other surface of the nut portion 93 opposite to the inner surface that forms the screw hole 97 faces the outside of the braking device 10 and is included in the outer surface 81 a.

[0066] The resin portion 83 is a resin portion of the lower case 71 manufactured by insert molding. The material of the resin portion 83 is, for example, a synthetic resin such as plastic. Therefore, the resin portion 83 has lower rigidity and density than the metal portion 81 and the nut 82. However, the rigidity and density of the resin portion 83 are not limited to this example. The resin portion 83 has a main body 101, an inner cylindrical portion 102, and an outer cylindrical portion 103.

[0067] The main body 101 has a connection surface 101a and a support surface 101b. In other words, the support surface 101b is provided on the resin portion 83. The support surface 101b may be provided on the metal portion 81. The connection surface 101a is provided at an end of the lower case 71 in the first axial direction Dx1. The main body 101 is provided with a recess 105 that opens to the connection surface 101a. The recess 105 is recessed from the connection surface 101a in the second axial direction Dx2.

[0068] The main body 101 at least partially accommodates the bearing 35, the gears 45, 46, 47, the support shaft 48, the rotating member 51, and the linear motion member 52 in the recess 105. For example, the main body 101 accommodates the flange 56 and a portion of the cylindrical wall 55 of the rotating member 51 that includes the second outer circumferential surface 55b in the recess 105. In addition, the support shaft 48 is fitted into a hole provided in the main body 101 and is supported by the main body 101.

[0069] The support surface 101b is provided in the recess 105. In other words, the support surface 101b is a part of the inner surface of the main body 101 that forms the recess 105. The recess 105 is a substantially annular flat surface facing the first axial direction Dx1.

[0070] The support surface 101b supports the outer race 62 of the bearing 35 in the axial direction. Therefore, the support surface 101b supports the rotating member 51 via the bearing 35. The inner diameter of the support surface 101b is equal to or smaller than the inner diameter of the outer race 62. The outer diameter of the support surface 101b is equal to or larger than the outer diameter of the outer race 62. The support surface 101b is spaced apart from the inner race 61.

[0071] The metal portion 81 is provided between the support surface 101b and the backing plate 12. The cylindrical portion 91 of the metal portion 81 surrounds the cable 23 that passes through the inside of the bearing 35 and the rotating member 51 and extends in the axial direction.

[0072] The diameter of the inner peripheral surface 91a of the cylindrical portion 91 (the inner diameter of the cylindrical portion 91) is smaller than the outer diameter of the support surface 101b. The diameter of the outer peripheral surface 91b of the cylindrical portion 91 (the outer diameter of the cylindrical portion 91) is larger than the inner diameter of the support surface 101b. The cylindrical portion 91 overlaps the support surface 101b in the axial direction.

[0073] The portion 83a of the resin portion 83 including the support surface 101b is interposed between the support surface 101b and the end portion 91c of the cylindrical portion 91 in the first axial direction Dx1. The portion 83a covers the end portion 91c of the cylindrical portion 91 and does not expose the metal portion 81 in the recess 105.

[0074] A plurality of nuts 82 are embedded in the main body 101. Screw holes of the plurality of nuts 82 open on the connection surface 101a. On the connection surface 101a, the nuts 82 may be covered by the resin portion 83 or may be exposed.

[0075] The inner cylindrical portion 102 extends from the main body 101 in the second axial direction Dx2. The inner cylindrical portion 102 covers the inner circumferential surface 91 a of the cylindrical portion 91 over the entire circumferential direction. In other words, the inner cylindrical portion 102 is provided in the through-hole 95 of the cylindrical portion 91 and is formed in a substantially cylindrical shape extending along the central axis Axc. Note that a portion of the inner circumferential surface 91 a in the axial direction may be exposed and not covered by the inner cylindrical portion 102.

[0076] The inner cylindrical portion 102 has an inner circumferential surface 102a and a protruding portion 102b. The inner circumferential surface 102a may also be referred to as a sealing surface. The inner circumferential surface 102a is a substantially cylindrical curved surface extending along the central axis Axc and facing the central axis Axc. The protruding portion 102b protrudes radially inward from an end of the inner circumferential surface 102a in the first axial direction Dx1.

[0077] The inner cylinder portion 102 is formed in a generally cylindrical shape along the inner circumferential surface 91 a of the cylinder portion 91. Therefore, a passage 106 is provided inside the inner cylinder portion 102. The inner circumferential surface 102 a forms a part of the passage 106. The passage 106 extends along the central axis Axc and communicates with the recess 105.

[0078] The cable 23 extends through the passage 106. The guide member 37 is disposed in the passage 106 and supported by the protrusion 102b. The pipe member 25 and the pipe seal 38 are housed in the passage 106 on the inside of the inner circumferential surface 102a.

[0079] The end of the pipe member 25 in the first axial direction Dx1 abuts against the protruding portion 102 b or is spaced from the protruding portion 102 b in the second axial direction Dx2. The pipe seal 38 contacts the pipe member 25 and the inner circumferential surface 102 a and is spaced from the metal portion 81.

[0080] The pipe seal 38 seals the gap between the pipe member 25 and the lower case 71, between the pipe member 25 and the inner circumferential surface 102a. In the axial direction, the length of the inner circumferential surface 102a is longer than the length of the portion where the inner circumferential surface 102a and the pipe seal 38 contact each other.

[0081] The outer cylinder portion 103 extends in the second axial direction Dx2 from the main body 101. The outer cylinder portion 103 covers the outer peripheral surface 91b of the cylinder portion 91 over the entire circumferential direction. Therefore, the cylinder portion 91 is located between the inner cylinder portion 102 and the outer cylinder portion 103.

[0082] In the present embodiment, the outer tubular portion 103 covers the entire outer surface 81a of the metal portion 81. That is, the outer tubular portion 103 covers not only the tubular portion 91 but also the flange portion 92 and the nut portion 93. Therefore, in the lower case 71 attached to the backing plate 12, the metal portion 81 is not exposed to the outside of the braking device 10.

[0083] The upper case 72 is basically made of a synthetic resin such as plastic. In the example of Fig. 3, the upper case 72 has a plurality of resin members, nuts and sleeves embedded in the plurality of members, and screws that connect the plurality of members to each other. Note that the upper case 72 is not limited to this example, and may be made entirely of resin or entirely of metal.

[0084] The upper case 72 has a connection surface 72a. The connection surface 72a is a surface made of resin. That is, the connection surface 72a is provided on a resin member of the upper case 72. The connection surface 72a is provided on an end of the upper case 72 in the second axial direction Dx2.

[0085] The connecting surface 72a of the upper case 72 and the connecting surface 101a of the main body 101 of the lower case 71 face each other. The two connecting surfaces 72a, 101a are sealed between each other, for example, by contacting each other or by interposing a sealant or sealing material between the two connecting surfaces 72a, 101a. The sealing material is, for example, silicone resin, synthetic rubber, or a gasket. The upper case 72 is spaced from the metal portion 81.

[0086] The upper case 72 is provided with a recess 111 and a plurality of insertion holes 112. The recess 111 opens to the connection surface 72a. The recess 111 is recessed from the connection surface 72a in the first axial direction Dx1. The upper case 72 at least partially accommodates the motor 32, the cable end 36, the gear 45, the support shaft 48, the rotating member 51, and the linearly moving member 52 in the recess 111.

[0087] The insertion holes 112 are through-holes that open to the connection surface 72 a. The insertion holes 112 communicate with the threaded holes of the nuts 82 of the lower case 71. The fasteners 73 are passed through the insertion holes 112 and screwed into the threaded holes of the nuts 82 to attach the upper case 72 to the lower case 71.

[0088] The recess 105 and the passage 106 of the lower case 71 and the recess 111 of the upper case 72 form an internal space S of the housing 31. 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 bearing 35, the cable end 36, the guide member 37, and the pipe seal 38 in the internal space S. That is, the upper case 72 accommodates the rotating member 51 and the linearly moving member 52 together with the lower case 71.

[0089] When the linear motion member 52 pulls the cable 23 in the first axial direction Dx1, a reaction force acts on the linear motion member 52. The reaction force acts on the support surface 101b of the lower case 71 via the linear motion member 52, the rotating member 51, and the bearing 35. The support surface 101b receives a load in the second axial direction Dx2 as the reaction force.

[0090] The metal portion 81 is provided between the support surface 101b that receives the reaction force and the backing plate 12 to which the lower case 71 is attached. The cylindrical portion 91 extends in substantially the same direction (axial direction) as the second axial direction Dx2 in which the reaction force acts on the support surface 101b. Therefore, the lower case 71 can obtain strength (rigidity) sufficient to withstand the reaction force between the support surface 101b and the backing plate 12. In other words, the metal portion 81 reinforces the lower case 71 between the support surface 101b and the backing plate 12.

[0091] The pipe seal 38 restricts the intrusion of liquid into the internal space S of the housing 31. When the pipe seal 38 is in contact with metal, measures such as installing the pipe seal 38 with consideration for the up-down orientation are taken to prevent liquids such as rainwater, which can cause metal corrosion, from coming into contact with the metal in contact with the pipe seal 38. However, the pipe seal 38 is in contact with the inner cylindrical portion 102 of the resin part 83. Therefore, the braking device 10 prevents a gap from forming between the pipe seal 38 and the lower case 71 due to expansion of the metal caused by corrosion.

[0092] The connecting surface 72a of the upper case 72, together with the connecting surface 101a of the lower case 71, seals the gap between the two connecting surfaces 72a, 101a, restricting the intrusion of liquid into the interior space S of the housing 31. If the connecting surfaces 72a, 101a were made of metal, measures such as applying a sealant would be taken to prevent liquids such as rainwater, which can cause metal corrosion, from coming into contact with the metal. However, the connecting surfaces 72a, 101a are made of resin. Therefore, the brake device 10 prevents a gap from forming between the lower case 71 and the upper case 72 due to expansion of the metal caused by corrosion.

[0093] Within the internal space S of the housing 31, inside the pipe seal 38, the resin portion 83 covers the entire metal portion 81. For example, the end 91c of the tubular portion 91 is also covered by the resin portion 83. Therefore, even if the metal portion 81 corrodes, the braking device 10 prevents the corrosion from progressing to the internal space S or the metal from expanding due to corrosion, creating a gap connecting the internal space S to the outside.

[0094] In the braking device 10 according to the present embodiment described above, the brake shoe 11 is configured to brake the wheel 2 by contacting the drum rotor 3, which rotates integrally with the wheel 2, and is supported by the backing plate 12. The rotating member 51 is rotatable about the central axis Axc. The linearly-acting member 52 is attached to the rotating member 51 so as to move axially along the central axis Axc in response to the rotation of the rotating member 51. The cable 23 is supported by the linearly-acting member 52 and configured to be pulled by the linearly-acting member 52 to bring the brake shoe 11 into contact with the drum rotor 3. The lower case 71 is attached to the backing plate 12 and has a support surface 101b, a metal portion 81, and a resin portion 83. The support surface 101b supports the rotating member 51. The metal portion 81 is provided between the support surface 101b and the backing plate 12 and surrounds the cable 23. The resin portion 83 is formed integrally with the metal portion 81 and accommodates the rotating member 51 at least partially.

[0095] When the linear motion member 52 pulls the cable 23, a reaction force of the cable 23 acts on the support surface 101b via the linear motion member 52 and the rotating member 51. The lower case 71 has a metal portion 81 made of metal between the support surface 101b and the backing plate 12, thereby obtaining a strength sufficient to withstand the reaction force. On the other hand, the lower case 71 has a resin portion 83 as a portion for accommodating the rotating member 51, on which the reaction force is less likely to act. Resin generally has a lower density than metal. This allows the brake device 10 to be lighter and therefore less expensive than if the entire lower case 71 were made of metal.

[0096] The upper case 72 has a resin connection surface 72a that, together with the resin portion 83, seals the space between the upper case 72 and the resin portion 83. The upper case 72 is attached to the lower case 71 so as to be spaced apart from the metal portion 81 and accommodate the rotating member 51 and the linearly moving member 52 together with the lower case 71. That is, the resin portion 83 of the lower case 71 and the resin connection surface 72a of the upper case 72 seal the space between the resin portion 83 and the connection surface 72a. This prevents a gap from being generated between the lower case 71 and the connection surface 72a of the upper case 72 due to, for example, metal corrosion, and ultimately enables the brake device 10 to more reliably maintain a seal between the lower case 71 and the upper case 72.

[0097] The pipe member 25 surrounds the cable 23. The pipe seal 38 contacts the resin portion 83 and is spaced from the metal portion 81, sealing the gap between the lower case 71 and the pipe member 25. That is, the resin portion 83 of the lower case 71 and the pipe seal 38 contact each other. This prevents the brake device 10 from forming a gap due to, for example, metal corrosion at the contact portion (inner circumferential surface 102a) between the lower case 71 and the pipe seal 38, thereby more reliably maintaining a seal between the lower case 71 and the pipe seal 38.

[0098] The metal portion 81 has an outer surface 81a that faces the outside of the brake device 10. The resin portion 83 covers the entire outer surface 81a. The resin portion 83 protects the outer surface 81a of the metal portion 81 and prevents the metal portion 81 from being exposed to the outside of the brake device 10. This prevents corrosion of the metal portion 81 in the brake device 10, and ultimately allows the seal provided by the lower case 71 to be more reliably maintained.

[0099] The support surface 101b is provided on the resin portion 83. By providing the support surface 101b on the resin portion 83, the metal portion 81 is spaced apart from the rotating member 51 or components such as the bearing 35 that are interposed between the rotating member 51 and the support surface 101b. That is, the resin portion 83 covers the entire metal portion 81 in the portion of the internal space S of the housing 31 that is inside the pipe seal 38 and includes the support surface 101b. Therefore, even if the metal portion 81 corrodes, the braking device 10 prevents the corrosion from progressing to the internal space S or the metal from expanding due to corrosion, creating a gap connecting the internal space S to the outside. Furthermore, because the support surface 101b is made of resin, it can be prevented from expanding due to corrosion, for example, and thus the rotating member 51 can be prevented from being displaced from a desired position.

[0100] The braking device according to at least one embodiment described above includes, for example, a backing plate, a braking member configured to brake the wheel by contacting a drum rotor that rotates integrally with the wheel and supported by the backing plate, a rotating member rotatable about a central axis, a linearly-acting member attached to the rotating member so as to move axially along the central axis in response to the rotation of the rotating member, a cable supported by the linearly-acting member and configured to contact the braking member with the drum rotor when pulled by the linearly-acting member, and a first case including: a support surface attached to the backing plate and supporting the rotating member, a metal first portion disposed between the support surface and the backing plate and surrounding the cable, and a resin second portion formed integrally with the first portion and at least partially housing the rotating member. Therefore, for example, when the linearly-acting member pulls the cable, a reaction force of the cable acts on the support surface via the linearly-acting member and the rotating member. The first case has a first metal portion between the support surface and the backing plate, providing the first case with the strength to withstand the reaction force. Meanwhile, the first case has a second resin portion for accommodating the rotating member, which is less susceptible to the reaction force. Resin generally has a lower density than metal. This allows the braking device to be lighter and therefore less expensive than if the entire first case were made of metal.

[0101] As an example, the braking device further includes a second case having a resin connection surface that seals the second case together with the second case, the second case being spaced apart from the first case and attached to the first case so as to accommodate the rotating member and the linearly moving member together with the first case. Thus, as an example, as described above, the resin second case of the first case, the resin connection surface of the second case, and the connection surface of the second case are sealed. This prevents gaps from forming between the connection surfaces of the first case and the second case due to, for example, metal corrosion, and thus more reliably maintains a seal between the first case and the second case.

[0102] As an example, the braking device further includes a pipe member surrounding the cable and a seal member that contacts the second portion, is spaced from the first portion, and seals between the first case and the pipe member. Thus, as an example, as described above, the resin second portion of the first case and the seal member contact each other. This prevents the braking device from forming a gap at the contact point between the first case and the seal member due to, for example, metal corrosion, thereby more reliably maintaining a seal between the first case and the seal member.

[0103] In the braking device, for example, the first portion has an outer surface facing the outside of the braking device, and the second portion covers the entire outer surface. Thus, for example, the resin second portion protects the outer surface of the metal first portion and prevents the first portion from being exposed to the outside of the braking device. This prevents corrosion of the first portion of the braking device and more reliably maintains the sealing provided by the first case.

[0104] In the braking device, for example, the support surface is provided on the second portion. Therefore, for example, by providing the support surface on the second portion, the metal first portion is spaced from the rotating member or components, such as bearings, interposed between the rotating member and the support surface. That is, the resin second portion can cover the entire metal first portion in a portion of the internal space, which is at least partially formed by the first case and accommodates various components, such as the rotating member, including the support surface. Therefore, even if the first portion corrodes, the braking device can prevent corrosion from progressing to the internal space or from creating a gap connecting the internal space to the outside due to metal expansion caused by corrosion. Furthermore, because the support surface is made of resin, it can prevent expansion due to corrosion, for example, and thus prevent the rotating member from being displaced from its desired position.

[0105] 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.

Claims

1. A braking device comprising: a backing plate; a braking member supported by the backing plate and configured to brake a wheel by contacting a drum rotor that rotates integrally with the wheel; a rotating member rotatable about a central axis; a linear motion member attached to the rotating member so as to move in an axial direction along the central axis in response to rotation of the rotating member; a cable supported by the linear motion member and configured to contact the braking member with the drum rotor by being pulled by the linear motion member; and a first case attached to the backing plate and having a support surface for supporting the rotating member, a first metal portion provided between the support surface and the backing plate and surrounding the cable, and a second resin portion formed integrally with the first portion and at least partially accommodating the rotating member.

2. The braking device according to claim 1, further comprising a second case having a resin connection surface that seals between the second case and the second portion, is spaced apart from the first portion, and is attached to the first case so as to accommodate the rotating member and the linear motion member together with the first case.

3. The braking device according to claim 1, further comprising a pipe member surrounding the cable and a seal member that contacts the second portion, is spaced apart from the first portion, and seals between the first case and the pipe member.

4. The braking device according to claim 1, wherein the first portion has an outer surface facing the outside of the braking device, and the second portion covers the entire area of the outer surface.

5. The braking device according to claim 1, wherein the support surface is provided on the second portion.

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