Electromagnetic brake device

Abstract

To provide an electromagnetic brake device capable of preventing a rotational shaft, with which a brake hub is engaged through a spline formed on a free end side of the rotational shaft, from directly abutting against the brake hub in a direction orthogonal to an axis direction of the rotational shaft.SOLUTION: An electromagnetic brake device 100 comprises: a brake hub 34 having an inner peripheral part 34a that engages with a rotational shaft 15 via a spline 15c formed on a free end side of the rotational shaft 15, and supports a brake plate 35; a stopper part 10 that is fixed to the free end of the rotational shaft 15, and restricts movement of the brake hub 34 toward the free end side of the rotational shaft 15; and a buffer member 25 that is provided at a portion where the brake hub 34 and the stopper part 10 face each other along a radial direction of the brake hub 34.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an electromagnetic brake device. [Background technology]

[0002] BACKGROUND ART Conventionally, a technique for preventing the generation of abnormal noise by providing a buffer material that suppresses relative axial movement between a first rotating element and a second rotating element is known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6981182 Summary of the Invention [Problem to be solved by the invention]

[0004] An example of an electromagnetic brake used as a parking brake in an electric forklift or the like is a configuration in which the brake is attached to a rotating shaft of the motor that protrudes from one end of the drive motor. In this configuration, the motor's rotating shaft becomes a free end and can vibrate in a direction perpendicular to the axial direction. As a result, there is a risk of abnormal noise being generated when the brake hub supporting the brake plate and the rotating shaft directly come into contact with each other at the portion where the brake hub and the rotating shaft are engaged by a spline fit.

[0005] The present invention aims to provide an electromagnetic brake device that can prevent a rotating shaft, to which a brake hub is engaged via a spline formed on the free end side of the rotating shaft, from directly hitting the brake hub in a direction perpendicular to the axial direction of the rotating shaft. [Means for solving the problem]

[0006] An electromagnetic brake device according to one aspect of the present invention comprises a brake hub having an inner peripheral portion that engages with a rotating shaft via a spline formed on the free end side of the rotating shaft and that supports a brake plate; a stopper portion that is fixed to the free end of the rotating shaft and that restricts movement of the brake hub toward the free end of the rotating shaft; and a buffer member provided at a portion where the brake hub and the stopper portion face each other radially of the brake hub.

[0007] In an electromagnetic brake device according to one aspect of the present invention, a buffer member is provided at a portion where the brake hub and the stopper portion face each other in the radial direction of the brake hub. Because the stopper portion is fixed to the free end of the rotating shaft, the buffer member is located closer to the free end than the splines on the rotating shaft. As a result, when the free end of the rotating shaft vibrates in a direction perpendicular to the axial direction of the rotating shaft, the buffer member is sandwiched between the brake hub and the stopper portion before the brake hub and the rotating shaft directly come into contact with each other at the splines on the rotating shaft. Therefore, it is possible to prevent the rotating shaft, with which the brake hub engages via the splines formed on the free end side of the rotating shaft, from directly coming into contact with the brake hub in a direction perpendicular to the axial direction of the rotating shaft.

[0008] In one embodiment, the brake hub may have a recess that accommodates the stopper portion, and the buffer member may be provided between the inner peripheral surface of the recess of the brake hub and the outer peripheral surface of the stopper portion. In this case, the amount by which the stopper portion protrudes from the brake hub in the axial direction of the rotating shaft can be reduced, and the buffer member can be provided by utilizing the space in the recess.

[0009] In one embodiment, the brake disc may be engaged via a spline formed on the outer periphery of the brake hub. In this case, because there are two splines, one between the inner periphery of the brake hub and the rotating shaft and the other between the outer periphery of the brake hub and the brake disc, the brake hub is prone to rattle. Therefore, the buffer member has a significant effect of preventing direct contact between the brake hub and the rotating shaft.

[0010] An electromagnetic brake device according to another aspect of the present invention comprises a brake hub having an inner peripheral portion that engages with the rotating shaft via a spline formed on the free end side of the rotating shaft and that supports a brake plate; a stopper portion that is fixed to the free end of the rotating shaft and that restricts movement of the brake hub toward the free end of the rotating shaft; and a buffer member provided at a portion where the brake hub and an outer peripheral opposing surface provided on the free end side of the spline of the rotating shaft face each other radially of the brake hub.

[0011] In an electromagnetic brake device according to another aspect of the present invention, a buffer member is provided at a portion where the outer peripheral opposing surface of the rotating shaft and the brake hub face each other in the radial direction of the brake hub. Because the outer peripheral opposing surface is provided closer to the free end than the splines of the rotating shaft, the buffer member is located closer to the free end than the splines of the rotating shaft. As a result, when the free end of the rotating shaft vibrates in a direction perpendicular to the axial direction of the rotating shaft, the buffer member is sandwiched between the brake hub and the outer peripheral opposing surface before the brake hub and the rotating shaft directly come into contact with each other at the splines of the rotating shaft. Therefore, it is possible to prevent the rotating shaft, with which the brake hub engages via the splines formed on the free end of the rotating shaft, from directly coming into contact with the brake hub in a direction perpendicular to the axial direction of the rotating shaft. [Effects of the Invention]

[0012] According to the present invention, it is possible to prevent a rotating shaft to which a brake hub is engaged via a spline formed on the free end side of the rotating shaft from directly contacting the brake hub in a direction perpendicular to the axial direction of the rotating shaft. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a partial cross-sectional view of an electric motor and an electromagnetic brake device according to a first embodiment. [Figure 2] 1 is a longitudinal sectional view of a main part of an electromagnetic brake device according to a first embodiment. [Figure 3] FIG. 10 is a longitudinal sectional view of a main part of an electromagnetic brake device according to a second embodiment. [Figure 4]FIG. 10 is a vertical cross-sectional view of a main part of an electromagnetic brake device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent elements are designated by the same reference numerals, and redundant description will be omitted.

[0015] [First embodiment] Fig. 1 is a partial cross-sectional view of an electric motor and an electromagnetic brake device according to a first embodiment. As shown in Fig. 1, an electromagnetic brake device 100 is provided for an electric motor 11. The electromagnetic brake device 100 is provided at one of both axial ends of the electric motor 11, at an end 11b opposite one end 11a which becomes an output shaft 23 described below.

[0016] The electric motor 11 is an electric motor mounted on a vehicle for driving the vehicle. The vehicle is, for example, an industrial vehicle such as a forklift. The electric motor 11 includes a rotor 12 and a stator 13. The rotor 12 has a cylindrical rotor core 14 and a rotating shaft 15 that passes through and is fixed to the rotor core 14. The rotating shaft 15 protrudes from both ends of the rotor core 14 in the axial direction of the electric motor 11.

[0017] The stator 13 has a cylindrical stator core 16 and a stator coil 17. Coil ends 18 of the stator coil 17 are formed at both ends of the stator core 16 in the axial direction of the electric motor 11. In the example of Fig. 1, the coil end 18 at one end of the stator core 16 is shown, and the coil end 18 at the other end is not shown. A female screw hole 20 is formed in the center of the end of the rotating shaft 15 on the electromagnetic brake device 100 side.

[0018] The electric motor 11 includes an output side bracket 19 attached to the stator 13 on the end 11a side in the axial direction of the electric motor 11, and a brake side bracket 21 attached to the stator 13 on the end 11b side. The output side bracket 19 and the brake side bracket 21 are connected by a through bolt (not shown).

[0019] The output-side bracket 19 rotatably supports the rotary shaft 15 on the end 11a side via a bearing (not shown). The end of the rotary shaft 15 on the end 11a side protrudes from the output-side bracket 19 as an output shaft 23.

[0020] The brake-side bracket 21 rotatably supports the rotating shaft 15 on the end 11b side via a bearing 22. An end 15a of the rotating shaft 15 on the end 11b side protrudes from the brake-side bracket 21 as a braking shaft 15b (rotating shaft).

[0021] The brake shaft 15b is a part of the rotating shaft 15 that protrudes axially further outward from the electric motor 11 than the bearing 22. The brake shaft 15b is journaled by the bearing 22 and extends in a cantilevered manner from the bearing 22 to the end 15a. The end 15a of the brake shaft 15b corresponds to the "free end of the rotating shaft 15." The part of the brake shaft 15b from the bearing 22 to the end 15a corresponds to the "free end side of the rotating shaft 15."

[0022] The electromagnetic brake device 100 is configured as a non-excitation braking type electromagnetic brake device that is in a braking state when not excited, so that it can be used as a parking brake for a vehicle. The electromagnetic brake device 100 is attached to an end face 21a of a brake-side bracket 21. The end face 21a is one of the axial end faces of the brake-side bracket 21 that is on the end 15a side of the brake shaft 15b. The electromagnetic brake device 100 is configured to be able to brake the rotation of the rotor 12.

[0023] Fig. 2 is a longitudinal cross-sectional view of the main parts of the electromagnetic brake device according to the first embodiment. As shown in Fig. 2, the electromagnetic brake device 100 has a brake stator 31, a brake armature 32, a fixed plate 33, a brake hub 34, and a brake plate 35.

[0024] The brake stator 31 has a stator body 37 that is provided along the end surface 21a of the brake-side bracket 21. The stator body 37 has an annular shape, and a circular hole 38 is formed in the center of the stator body 37. The circular hole 38 may accommodate, for example, the brake shaft 15b and a portion of the brake hub 34.

[0025] An annular electromagnetic coil 39 serving as an attraction mechanism is built into the stator main body 37. The electromagnetic coil 39 excites the brake stator 31 when energized, and de-energizes the brake stator 31 when de-energized.

[0026] The stator main body 37 has a through hole 42 through which a bolt 41 is inserted. The bolt 41 is a fastening member that fixes the electromagnetic brake device 100 to the electric motor 11. The stator main body 37 has a female threaded hole 62 that is threadedly engaged with a bolt 61. As will be described in detail later, the bolt 61 is a fastening member that fixes the fixing plate 33 to the brake stator 31. The brake-side bracket 21 is provided with a female threaded hole 43 that is threadedly engaged with the bolt 41 and communicates with the through hole 42. Although only one set of bolts 41, 61, through hole 42, and female threaded holes 43, 62 is shown in the example of FIG. 2 , multiple sets may be provided. The bolt 41 inserted into the through hole 42 is threadedly engaged with the female threaded hole 43, thereby fastening the brake stator 31 to the brake-side bracket 21 and fixing the electromagnetic brake device 100 to the electric motor 11. The bolts 41, 61 are, for example, hexagon socket head bolts. The head of the bolt 41 can be fastened through the through-hole 32 a of the brake armature 32 and the through-hole 33 a of the fixing plate 33 .

[0027] The stator body 37 has a plurality of bottomed holes 44 arranged at equal intervals around the circumferential direction of the stator body 37. A coil spring 45 is embedded in each of the plurality of bottomed holes 44. The coil spring 45 is a biasing member that biases the brake armature 32. One axial end of the coil spring 45 abuts against the brake stator 31, and the other axial end abuts against the brake armature 32. The coil spring 45 biases the brake armature 32 in the axial direction in a direction away from the brake stator 31.

[0028] The brake armature 32 faces the brake stator 31 in a direction along the axis P of the rotating shaft 15 (hereinafter simply referred to as the "axial direction"). The brake armature 32 is disk-shaped, and the brake shaft 15b and the brake hub 34 pass through the center of the brake armature 32. The brake armature 32 is provided so as to be movable along the axial direction, for example, by inserting a bolt 61 into a cylindrical distance collar 64 disposed in a U-shaped groove 32b that has a U-shape when viewed axially. The distance collar 64 abuts against the inner wall surface of the U-shaped groove 32b in the circumferential direction, thereby restricting the circumferential movement of the brake armature 32 within a certain range.

[0029] The fixed plate 33 is disposed on the opposite side of the brake armature 32 from the brake stator 31 in the axial direction. The fixed plate 33 is disk-shaped, and the brake hub 34 passes through its center. A bolt 61 is inserted into the through hole 33b of the fixed plate 33, with the fixed plate 33 abutting against the brake stator 31 via, for example, a distance collar 64. By being sandwiched between the head of the bolt 61 and the distance collar 64, the fixed plate 33 is fixed in the axial direction at a position that is a predetermined distance from the brake stator 31, and is fixed integrally to the brake stator 31 in the circumferential direction.

[0030] The electromagnetic brake device 100 includes a brake hub 34 that supports a brake plate 35. The brake hub 34 has an inner peripheral portion 34a that is a through hole through which a brake shaft 15b is inserted. A spline 15c is formed on the brake shaft 15b over a predetermined range from the end portion 15a toward the bearing 22. A spline 34b that can mate with the spline 15c is formed on the inner peripheral portion 34a of the brake hub 34, for example, over the entire axial direction of the inner peripheral portion 34a. The spline 34b and the spline 15c are configured to be mateable with each other. The brake hub 34 is inserted with the spline 34b of the inner peripheral portion 34a mated with the spline 15c of the brake shaft 15b, and thus meshes with the brake shaft 15b. In other words, the brake hub 34 has an inner peripheral portion 34a that engages with the rotating shaft 15 via the spline 15c formed on the free end side of the rotating shaft 15. The brake hub 34, which is spline-fitted with the brake shaft 15b, rotates integrally with the brake shaft 15b in the circumferential direction, but can slide relative to the brake shaft 15b in the axial direction of the brake shaft 15b. The brake hub 34 can slide relative to the brake shaft 15b within the extension range of the splines 15c.

[0031] The brake plate 35 is a disc-shaped member disposed between the brake armature 32 and the fixed plate 33 in the axial direction of the brake shaft 15b. A friction material 46 that comes into contact with the brake armature 32 in a braking state and a friction material 47 that comes into contact with the fixed plate 33 in a braking state are fixed to the plate surface of the brake plate 35.

[0032] The brake plate 35 has an inner peripheral portion 35a that is inserted into the brake hub 34. The brake hub 34 has splines 34e formed in a predetermined range from an end portion 34d on an outer peripheral portion 34c of the brake hub 34. The inner peripheral portion 35a of the brake plate 35 has splines 35b that can mate with the splines 34e, for example, formed over the entire axial direction of the inner peripheral portion 35a. The splines 34e and 35b are configured to be able to mate with each other. The brake plate 35 is inserted with the splines 35b of the inner peripheral portion 35a mated with the splines 34e of the brake hub 34, and thus meshes with the brake hub 34. In other words, the brake plate 35 is engaged via the splines 34e formed on the outer peripheral portion 34c of the brake hub 34. The brake plate 35, which is spline-fitted with the brake hub 34, rotates integrally with the brake hub 34 in the circumferential direction, but can slide relative to each other in the axial direction of the brake hub 34. The brake plate 35 is slidably movable relative to the brake hub 34 in the range between the brake armature 32 and the fixed plate 33 .

[0033] In the electromagnetic brake device 100 configured as described above, when the electromagnetic coil 39 is excited by energizing it, the brake armature 32 is attracted to the brake stator 31 against the biasing force of the coil spring 45. The brake armature 32 moves away from the brake plate 35, and the brake plate 35 is released from the pressing force against the fixed plate 33. As a result, the brake shaft 15b is no longer braked, and the rotating shaft 15 is free to rotate because it does not receive frictional forces between the brake armature 32 and the brake plate 35, and between the brake plate 35 and the fixed plate 33.

[0034] On the other hand, when the electromagnetic coil 39 is not energized and is not excited, the brake armature 32 is pressed toward the brake plate 35 by the biasing force of the coil spring 45, and the brake plate 35 is pressed against the fixed plate 33. The brake plate 35 is sandwiched between the brake armature 32 and the fixed plate 33. As a result, frictional forces are generated between the brake armature 32 and the brake plate 35 and between the brake plate 35 and the fixed plate 33, braking the rotating shaft 15 and activating the parking brake.

[0035] A stopper portion 10 is provided on the end 15a of the brake shaft 15b. The stopper portion 10 prevents the brake hub 34, which is spline-fitted with the brake shaft 15b, from moving in the axial direction of the brake shaft 15b and coming off the brake shaft 15b. The stopper portion 10 is fixed to the end 15a of the brake shaft 15b by, for example, a bolt 24. The stopper portion 10 of this embodiment is a cylindrical member with an outer diameter larger than the outer diameter of the end 15a of the brake shaft 15b. The shaft portion of the bolt 24 is inserted into a through hole in the center of the stopper portion 10.

[0036] The brake hub 34 has a recess 36 that accommodates the stopper portion 10. The recess 36 is formed, for example, as a bottomed hole that defines a cylindrical space. One end face 10a of the stopper portion 10 faces a bottom face of the recess 36 of the brake hub 34 across a predetermined distance in the axial direction. Therefore, the brake hub 34 is movable in the axial direction of the brake shaft 15b between the one end face 10a of the stopper portion 10 and the terminal end of the spline 15c on the bearing 22 side. In other words, the stopper portion 10 is fixed to the end 15a of the brake shaft 15b (the free end of the rotating shaft 15) and restricts movement of the brake hub 34 toward the end 15a of the brake shaft 15b.

[0037] The inner diameter of the recess 36 of the brake hub 34 is larger than the outer diameter of the stopper portion 10. A gap of a predetermined distance is formed in the radial direction between the inner peripheral surface 36a of the recess 36 of the brake hub 34 and the outer peripheral surface 10b of the stopper portion 10. The brake hub 34 and the stopper portion 10 face each other in the radial direction of the brake hub 34 with this gap interposed therebetween.

[0038] A buffer member 25 is provided at a portion where the brake hub 34 and the stopper portion 10 face each other in the radial direction of the brake hub 34. The buffer member 25 is a member for suppressing abnormal noise from the brake hub 34. Abnormal noise from the brake hub 34 can be caused by, for example, vibration of the free end of the brake shaft 15b or the brake hub 34 itself in the radial direction.

[0039] In this embodiment, a buffer member 25 is provided in the gap formed between the inner circumferential surface 36a of the recess 36 of the brake hub 34 and the outer circumferential surface 10b of the stopper portion 10. The buffer member 25 may be, for example, an O-ring. A plurality of (e.g., two) grooves 10c are provided in the outer circumferential surface 10b of the stopper portion 10, and the buffer members 25 are fitted into these grooves 10c. The predetermined radial distance of the gap between the inner circumferential surface 36a and the outer circumferential surface 10b may be, for example, approximately the same as the radial dimension of the buffer member 25. The buffer member 25 is formed, for example, from an elastically deformable rubber material with a circular cross section. For example, if the gap between the inner circumferential surface 36a and the outer circumferential surface 10b becomes narrower than the predetermined distance, the buffer member 25 may elastically deform and come into contact with both the brake hub 34 and the stopper portion 10, thereby sandwiching the buffer member 25. The axial dimension of the stopper portion 10 may be, for example, a thickness according to the number of buffer members 25 and may be a thickness that does not protrude from the recess 36 of the brake hub 34.

[0040] Here, because the brake shaft 15b is a free end, the brake shaft 15b can vibrate in a direction perpendicular to the axial direction. When the free end of the brake shaft 15b vibrates in a direction perpendicular to the axial direction of the brake shaft 15b, a relative displacement between the brake hub 34 and the brake shaft 15b can occur, such that the gap between the inner peripheral surface 36a and the outer peripheral surface 10b becomes narrower than the predetermined gap. As a result, the brake hub 34, which supports the brake plate 35, and the brake shaft 15b may come into direct contact with each other at the portion where the brake hub 34 and the brake shaft 15b are engaged by spline fitting, which may cause abnormal noise.

[0041] In this regard, in the electromagnetic brake device 100, a buffer member 25 is provided at a portion where the brake hub 34 and the stopper portion 10 face each other in the radial direction of the brake hub 34. Because the stopper portion 10 is fixed to the end portion 15a of the brake shaft 15b, which is the free end of the rotating shaft 15, the buffer member 25 is located closer to the end portion 15a (free end side) than the splines 15c of the brake shaft 15b. As a result, when the brake shaft 15b vibrates in a direction perpendicular to the axial direction of the brake shaft 15b, the buffer member 25 is sandwiched between the brake hub 34 and the stopper portion 10 before the brake hub 34 and the brake shaft 15b directly come into contact with each other at the splines 15c of the brake shaft 15b. In other words, the buffer member 25 comes into contact with both the brake hub 34 and the stopper portion 10. The buffer member 25 leaves a gap between the inner circumferential surface 36a and the outer circumferential surface 10b corresponding to the elastically deformed buffer member 25, reducing the amplitude of vibration of the free end of the brake shaft 15b in a direction perpendicular to the axial direction of the brake shaft 15b. Therefore, the brake shaft 15b, which is engaged with the brake hub 34 via the spline 15c formed on the free end of the brake shaft 15b, can be prevented from directly contacting the brake hub 34 in a direction perpendicular to the axial direction of the brake shaft 15b. While the buffer member 25 may prevent direct contact between the brake hub 34 and the stopper portion 10, the brake hub 34 and the stopper portion 10 may also directly contact each other as a result of elastic deformation of the buffer member 25. In this case, the amplitude of vibration of the free end of the brake shaft 15b can be reduced in the same way as with the above-described action.

[0042] In the electromagnetic brake device 100, the brake hub 34 has a recess 36 that accommodates the stopper portion 10. The buffer member 25 is provided between an inner peripheral surface 36a of the recess 36 of the brake hub 34 and an outer peripheral surface 10b of the stopper portion 10. With this configuration, the amount by which the stopper portion 10 protrudes from the brake hub 34 in the axial direction of the rotating shaft 15 is suppressed, and the buffer member 25 can be provided by utilizing the space within the recess 36.

[0043] In the electromagnetic brake device 100, the brake plate 35 is engaged via splines 34e formed on the outer circumferential portion 34c of the brake hub 34. In this configuration, there are splines in two locations: the splines 15c between the inner circumferential portion 34a of the brake hub 34 and the brake shaft 15b, and the splines 34e between the outer circumferential portion 34c of the brake hub 34 and the brake plate 35, which tends to cause rattle in the brake hub 34. Therefore, the buffer member 25 has a significant effect of preventing the brake hub 34 and the brake shaft 15b from directly hitting each other.

[0044] [Second embodiment] Next, an electromagnetic brake device according to a second embodiment will be described. An electromagnetic brake device 100A according to the second embodiment differs from the electromagnetic brake device 100 in that a buffer member 25A is attached to a brake shaft 15d rather than to a stopper portion. Hereinafter, the same configuration as in the first embodiment will be referred to in the description of the first embodiment, and the same reference numerals will be used.

[0045] Fig. 3 is a longitudinal cross-sectional view of a main part of an electromagnetic brake device according to a second embodiment. As shown in Fig. 3, a brake shaft 15d, for example, has a small diameter portion 15e formed in a predetermined range from the end portion 15a toward the bearing 22, and a spline 15c formed in a predetermined range from the terminal end of the small diameter portion 15e on the bearing 22 side toward the bearing 22. The small diameter portion 15e has a smaller diameter than the portion of the brake shaft 15d where the spline 15c is formed, on the side closer to the end portion 15a (free end side) than the spline 15c of the brake shaft 15d.

[0046] The inner peripheral portion 34a of the brake hub 34A has splines 34b that can mate with the splines 15c formed in the axial direction at the portion where the splines 15c of the brake shaft 15d are formed. The end portion 34d of the inner peripheral portion 34a of the brake hub 34A is formed as an inner peripheral diameter portion 34f that protrudes radially inward to correspond to the small diameter portion 15e of the brake shaft 15d. The outer peripheral surface of the small diameter portion 15e of the brake shaft 15d faces the inner peripheral diameter portion 34f of the brake hub 34A on the free end side of the splines 15c of the brake shaft 15d. Therefore, the small diameter portion 15e is an outer peripheral facing surface provided on the free end side of the splines 15c of the brake shaft 15d.

[0047] A buffer member 25A is provided in a gap formed between an inner diameter portion 34f of the brake hub 34A and the small diameter portion 15e of the brake shaft 15d. That is, the buffer member 25A is provided at a portion where the small diameter portion 15e, which is provided closer to the end 15a (free end) than the spline 15c of the brake shaft 15d, and the brake hub 34A face each other in the radial direction of the brake hub 34A. The buffer member 25A can be, for example, an O-ring. A groove 15f is provided in the small diameter portion 15e of the brake shaft 15d, and the buffer member 25A is fitted into this groove 15f. The predetermined radial distance of the gap may be, for example, approximately the same as the radial dimension of the buffer member 25A.

[0048] In the electromagnetic brake device 100A, the stopper portion 40 may be a disk-shaped member having a smaller diameter than the stopper portion 10 of FIG.

[0049] In the electromagnetic brake device 100A, a buffer member 25A is provided at a portion where the small diameter portion 15e (outer peripheral facing surface) of the brake shaft 15d and the brake hub 34A face each other in the radial direction of the brake hub 34A. Because the small diameter portion 15e is provided closer to the end 15a (free end) than the splines 15c of the brake shaft 15d, the buffer member 25A is located closer to the end 15a than the splines 15c of the brake shaft 15d. As a result, when the end 15a of the brake shaft 15d vibrates in a direction perpendicular to the axial direction of the brake shaft 15d, the buffer member 25A is sandwiched between the brake hub 34A and the small diameter portion 15e before the brake hub 34A and the brake shaft 15d directly come into contact with each other at the splines 15c of the brake shaft 15d. Therefore, the brake shaft 15d, which engages with the brake hub 34A via the spline 15c formed on the free end side of the brake shaft 15d, can be prevented from directly contacting the brake hub 34A in a direction perpendicular to the axial direction of the brake shaft 15d.

[0050] [Third embodiment] Next, an electromagnetic brake device according to a third embodiment will be described. Electromagnetic brake device 100B according to the third embodiment differs from electromagnetic brake device 100 in that buffer member 25B is provided on the outer side of brake hub 34B at a portion where stopper portion 50 is located (on the inner periphery of the stopper portion), whereas electromagnetic brake device 100 has buffer member 25B provided on the inner side of brake hub 34B at a portion where stopper portion 10 is located (on the outer periphery of the stopper portion).

[0051] Fig. 4 is a longitudinal cross-sectional view of a main portion of an electromagnetic brake device according to a third embodiment. As shown in Fig. 4, brake hub 34B has protruding portion 34g that protrudes in the axial direction from end portion 34d. Protruding portion 34g protrudes from end portion 34d, for example, to form a cylindrical shape that is continuous in the circumferential direction. An outer peripheral surface 34h of protruding portion 34g may be located radially inward of outer peripheral portion 34c. The protruding length (axial dimension) of protruding portion 34g may be a thickness that corresponds to, for example, the number of buffer members 25B.

[0052] As an example, the stopper portion 50 has a base portion 51 fixed to the end portion 15a of the brake shaft 15b, an opposing portion 52 covering the protruding portion 34g of the brake hub 34B, and a connecting portion 53 connecting the base portion 51 and the opposing portion 52. The base portion 51 is a disk-shaped portion large enough to seat the bolt 24. The opposing portion 52 extends in the axial direction radially outward from the outer circumferential surface 34h of the protruding portion 34g of the brake hub 34B. The outer circumferential surface 34h of the protruding portion 34g of the brake hub 34B faces the opposing portion 52, which serves as the inner circumferential surface of the stopper portion 50, on the free end side of the spline 15c of the brake shaft 15b. The connecting portion 53 includes, for example, a cylindrical portion 53a standing in the axial direction from the outer circumferential portion of the base portion 51 and a disk portion 53b connecting the end of the cylindrical portion 53a and the end of the opposing portion 52.

[0053] A buffer member 25B is provided in a gap formed between the opposing portion 52 of the stopper portion 50 and the protruding portion 34g of the brake hub 34B. That is, the buffer member 25B is provided at a portion where the stopper portion 50, which is provided closer to the end portion 15a (free end side) than the spline 15c of the brake shaft 15b, and the brake hub 34B face each other in the radial direction of the brake hub 34B. The buffer member 25B may be, for example, an O-ring. A groove 52a is provided in the opposing portion 52 of the stopper portion 50, and the buffer member 25B is fitted into this groove 52a. The predetermined radial distance of the gap may be, for example, approximately the same as the radial dimension of the buffer member 25B.

[0054] In this electromagnetic brake device 100B, similarly to the electromagnetic brake device 100, when the brake shaft 15b vibrates in a direction perpendicular to the axial direction of the brake shaft 15b, the buffer member 25B is sandwiched between the brake hub 34B and the stopper portion 50 before the brake hub 34B and the brake shaft 15b come into direct contact with each other at the splines 15c of the brake shaft 15b. Therefore, the brake shaft 15b, with which the brake hub 34B is engaged via the splines 15c formed on the free end side of the brake shaft 15b, can be prevented from coming into direct contact with the brake hub 34B in the direction perpendicular to the axial direction of the brake shaft 15b.

[0055] [Variations] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments.

[0056] In the above-described embodiments, the brake hubs 34, 34A, 34B have the recesses 36 for accommodating the stopper portions 10, 40, 50, but the present invention is not limited to this. The recesses 36 may be omitted.

[0057] In each of the above embodiments, the brake plate 35 is engaged via the splines 34e formed on the outer circumferential portion 34c of the brake hub 34, but this is not limiting. The brake plate 35 and the brake hub 34 may be fixed to each other by a method other than splines, such as fastening with bolts or rivets.

[0058] In the above-described embodiments, grooves into which the buffer members are fitted are formed in the inner circumferential surface 36a of the recess 36 of the brake hub 34, the small diameter portion 15e of the brake shaft 15d, and the opposing portion 52 of the stopper portion 50, but this is not limiting. Grooves may also be formed in the inner circumferential surface 36a of the recess 36 of the brake hub 34, the inner diameter portion 34f of the brake hub 34A, and the outer circumferential surface 34h of the protruding portion 34g of the brake hub 34B.

[0059] In each of the above embodiments, the portion where the brake hub and the stopper portion face each other along the radial direction of the brake hub is a surface parallel to the axial direction, but it may also be a tapered surface inclined in the axial direction.

[0060] In the second embodiment, the small diameter portion 15e of the brake shaft 15d is exemplified as the outer peripheral facing surface, but the present invention is not limited to this. For example, the outer peripheral facing surface may have the same outer diameter as the root portion of the spline 15c and may not have a spline.

[0061] In the above embodiments, a rubber O-ring was used as an example of the buffer member, but this is not limiting. The buffer member may also be a bushing made of resin such as Duracon. Furthermore, the buffer member does not have to be annular, and may be discretely arranged at a portion where the brake hub and the stopper portion face each other in the radial direction of the brake hub. Furthermore, the cross-sectional shape of the buffer member is not limited to a circle, and may be a tapered triangle or the like. If the cross-sectional shape of the buffer member is tapered, braking torque is less likely to be transmitted from the brake hub to the stopper portion via the buffer member, and loosening of the bolt 24 due to braking torque can be suppressed. [Explanation of symbols]

[0062] 10, 40, 50... stopper portion, 10b... outer peripheral surface, 15... rotating shaft, 15b... brake shaft (rotating shaft), 15c, 34b, 34e, 35b... spline, 15e... small diameter portion (surface facing outer peripheral), 25, 25A, 25B... buffer member, 34, 34A, 34B... brake hub, 34a... inner peripheral portion, 34c... outer peripheral portion, 34h... outer peripheral surface, 35... brake plate, 35a... inner peripheral portion, 36... recess, 36a... inner peripheral surface, 100, 100A, 100B... electromagnetic brake device.

Claims

1. a brake hub having an inner circumferential portion that is engaged with the rotary shaft via a spline formed on a free end side of the rotary shaft and that supports a brake plate; a stopper portion fixed to the free end of the rotating shaft and restricting movement of the brake hub toward the free end of the rotating shaft; a buffer member provided at a portion where the brake hub and the stopper portion face each other in a radial direction of the brake hub.

2. The brake hub has a recess that accommodates the stopper portion, 2. The electromagnetic brake device according to claim 1, wherein the buffer member is provided between an inner peripheral surface of the recess of the brake hub and an outer peripheral surface of the stopper portion.

3. 3. The electromagnetic brake device according to claim 1, wherein the brake plate is engaged with the brake hub via a spline formed on an outer periphery of the brake hub.

4. a brake hub having an inner circumferential portion that is engaged with the rotary shaft via a spline formed on a free end side of the rotary shaft and that supports a brake plate; a stopper portion fixed to the free end of the rotating shaft and restricting movement of the brake hub toward the free end of the rotating shaft; an outer peripheral opposing surface provided on the rotating shaft closer to the free end than the spline; and a buffer member provided at a portion where the brake hub and the brake shaft face each other along the radial direction of the brake hub.

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