Electromagnetic brake device

Abstract

To provide an electromagnetic brake device for preventing the occurrence of abnormal sound during abutment between a brake hub and a locking member while enabling the entry suppression of foreign matters.SOLUTION: An electromagnetic brake device 10 includes a brake stator 31, a rotary shaft 15 rotatable with respect to the brake stator 31, a brake hub 34 fitted to the rotary shaft 15 and movable in the direction of an axial center P of the rotary shaft 15, a brake plate 35 fitted to the brake hub 34 in an integrally rotatable manner, and provided movable in the direction of the axial center P of the rotary shaft 15, and a locking member 52 provided on the rotary shaft 15 for preventing the come-off of the brake hub 34 from the rotary shaft 15. Between the brake hub 34 and the locking member 52, a buffer member 57 is laid.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This invention relates to an electromagnetic brake device.

Background Art

[0002] As a conventional technology of an electromagnetic brake device, for example, a non-excitation electromagnetic brake device disclosed in Patent Document 1 is known. The non-excitation electromagnetic brake device disclosed in Patent Document 1 includes a movable iron core, a rotating disk, a center hub, a rotating shaft, and a connecting member. The movable iron core is attracted by an electromagnet to release braking and is pushed by a braking spring to move only in the axial direction for braking. The rotating disk is disposed between the movable iron core and a braking plate. The center hub is coupled to the rotating disk so as to be movable only in the axial direction. The rotating shaft is fixed to the center hub and supported by a bearing. The connecting member secures the relative positions of the fixed iron core of the electromagnet and the braking plate.

[0003] Further, the non-excitation electromagnetic brake device of Patent Document 1 includes movement restricting means for restricting the movement distance of the rotating disk from the braking position to the release direction to a position smaller than the gap from the braking position to the release position of the movable iron core between the center hub or the rotating shaft and the rotating disk, and biasing means for biasing the rotating disk in the release direction with a force smaller than the force of the braking spring.

[0004] According to the non-excitation electromagnetic brake device of Patent Document 1, when braking is released, the rotating disk during rotation has its axial position determined between the movable iron core and the braking plate at the release position by the movement restricting means and the biasing means, and neither the movable iron core nor the braking plate slides, and it is stated that no sliding noise is generated.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, in some electromagnetic brake devices, a brake hub (center hub) may be provided so as to be axially slidable with respect to a rotating shaft. In this case, a retaining member for preventing the brake hub from coming off the rotating shaft is provided at the end of the rotating shaft. Then, when the rotating shaft rotates during non-braking, the brake hub may axially slide and repeatedly contact the retaining member. For this reason, not only abnormal noise is generated when the brake hub contacts the retaining member, but also there is a problem that foreign matter easily enters between the brake hub and the rotating shaft. When metal powder (foreign matter) enters between the brake hub and the rotating shaft, wear at the sliding portion between the brake hub and the rotating shaft is promoted.

[0007] The non-excited electromagnetic brake device of Patent Document 1 only restricts the sliding of the movable iron core and the brake plate to suppress the generation of sliding noise in the release direction of the rotating disk, and is not a technique for suppressing abnormal noise when the brake hub contacts the retaining member.

[0008] The present invention has been made in view of the above problems, and an object of the present invention is to provide an electromagnetic brake device capable of preventing the generation of abnormal noise when the brake hub contacts the retaining member and suppressing the entry of foreign matter.

Means for Solving the Problems

[0009] In order to solve the above problems, the present invention provides an electromagnetic brake device including a brake stator, a rotating shaft rotatable with respect to the brake stator, a brake hub fitted to the rotating shaft and movable in the axial direction of the rotating shaft, a brake plate fitted to be integrally rotatable with the brake hub and provided to be movable in the axial direction of the rotating shaft, and a retaining member provided on the rotating shaft for preventing the brake hub from coming off the rotating shaft, characterized in that a buffer member is interposed between the brake hub and the retaining member.

[0010] In the present invention, since a buffer member is interposed between the brake hub and the retaining member, the buffer member does not come into contact with the brake hub or the retaining member, and the generation of abnormal noise due to contact is prevented. Further, the buffer member interposed between the brake hub and the retaining member can prevent foreign matter from entering the sliding portion between the brake hub and the rotating shaft.

[0011] Further, in the electromagnetic brake device described above, the buffer member may be fixed to an end surface of the retaining member facing the brake hub, and a gap may be formed between the buffer member and the brake hub. In this case, the buffer member is fixed to the end surface of the retaining member facing the brake hub, and a gap is formed between the buffer member and the brake hub. Therefore, even when the brake hub has play in the circumferential direction with respect to the rotating shaft, the sliding contact between the buffer member and the brake hub can be suppressed due to the presence of the gap.

[0012] Further, in the electromagnetic brake device described above, the buffer member may be fixed to an end surface of the brake hub facing the retaining member, and a gap may be formed between the buffer member and the retaining member. In this case, the buffer member is fixed to the end surface of the brake hub facing the retaining member, and a gap is formed between the buffer member and the retaining member. Therefore, even when the brake hub has play in the circumferential direction with respect to the rotating shaft, the sliding contact between the buffer member and the retaining member can be suppressed due to the presence of the gap.

[0013] Further, in the electromagnetic brake device described above, the buffer member may be formed in a ring shape and arranged coaxially with the rotating shaft. In this case, since the buffer member is formed in a ring shape and arranged coaxially with the rotating shaft, the buffer member surrounds the periphery of the rotating shaft. Therefore, the entry of foreign matter into the sliding portion between the brake hub and the rotating shaft can be more effectively prevented.

[0014] Further, in the electromagnetic brake device described above, the buffer member may be configured to be formed of a rubber-based material or a spongy body. Since the buffer member is formed of a rubber-based material or a spongy body, even if the wear powder of the buffer member enters the sliding portion between the brake hub and the rotating shaft as foreign matter, the sliding portion between the brake hub and the rotating shaft is hardly affected by the wear powder.

Advantages of the Invention

[0015] According to the present invention, it is possible to provide an electromagnetic brake device capable of preventing the generation of abnormal noise when the brake hub and the retaining member come into contact with each other and suppressing the entry of foreign matter.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0017] (First Embodiment) Hereinafter, the electromagnetic brake device according to the first embodiment will be described with reference to the drawings. The electromagnetic brake device of the present embodiment is a non-excitation braking type electromagnetic brake device that becomes a braking state in a non-excited state. Further, the electromagnetic brake device of the present embodiment is an electromagnetic brake device provided in a traveling electric motor mounted on a vehicle, and the vehicle is a forklift as an industrial vehicle.

[0018] As shown in FIG. 1, the electromagnetic brake device 10 of the present embodiment is provided in an electric motor 11. First, the electric motor 11 will be described. The electric motor 11 includes a rotor 12 and a stator 13. The rotor 12 has a rotor core 14 and a rotating shaft 15 that is fixed through the rotor core 14. The rotating shaft 15 protrudes from both ends of the rotor 12. The stator 13 includes a cylindrical stator core 16 and a stator coil 17. Coil ends 18 of the stator coil 17 are formed at both end portions of the stator core 16. In FIG. 1, the coil end 18 at one end is not shown, and only the coil end 18 at the other end is shown. A screw hole 20 is formed at the center of the end portion of the rotating shaft 15 on the side of the electromagnetic brake device 10.

[0019] The electric motor 11 includes an output side bracket 19 attached to one end of the stator 13 and a brake side bracket 21 on the side of the electromagnetic brake device 10 attached to the other end of the stator 13. The output side bracket 19 rotatably supports the vicinity of one end of the rotating shaft 15 via a bearing (not shown). The brake side bracket 21 rotatably supports the vicinity of the other end of the rotating shaft 15 via a bearing 22. The output side bracket 19 and the brake side bracket 21 are connected by a through bolt (not shown). A part of the rotating shaft 15 protrudes from the output side bracket 19 as an output shaft 23. An electromagnetic brake device 10 is attached to the other end of the brake side bracket 21. Details of the electromagnetic brake device 10 will be described later.

[0020] A terminal block 24 is provided on the brake side bracket 21. A lead wire 25 is drawn out from the other coil end 18 of the stator coil 17, and the drawn lead wire 25 is drawn into the terminal block 24. The terminal block 24 has a terminal portion (not shown) that is connected to the lead wire 25 and can be connected to an external wiring connected to an external device (for example, an inverter). The lead wire 25 is a wiring for supplying power to the electric motor 11.

[0021] Next, an electromagnetic brake device 10 that can brake the rotation of the rotor 12 will be described. As shown in FIG. 2, the electromagnetic brake device 10 includes a brake stator 31, a brake armature 32, a fixing plate 33, a brake hub 34, a brake plate 35, and a brake cover 36.

[0022] As shown in FIG. 2, the brake stator 31 has a ring-shaped stator main body 37 and a circular hole 38 at the center of the stator main body 37. One end face of the stator main body 37 abuts against the brake side bracket 21. The other end of the rotating shaft 15 and a part of the brake hub 34 are accommodated in the circular hole 38. An annular electromagnetic coil 39 as an attracting mechanism is built into the stator main body 37. The electromagnetic coil 39 energizes the brake stator 31 when energized and de-energizes the brake stator 31 when the energization stops.

[0023] The stator main body 37 has a through hole 42 through which a bolt 41 for fixing the electromagnetic brake device 10 to the electric motor 11 is inserted. The brake side bracket 21 is provided with a screw hole 43 that faces the through hole 42 and allows the bolt 41 to be screwed in. The brake stator 31 is fixed to the brake side bracket 21 by screwing the bolt 41 inserted through the through hole 42 into the screw hole 43. The plurality of bolts 41 penetrate the brake armature 32 and the fixing plate 33 respectively to fix the brake stator 31 to the electric motor 11.

[0024] The stator main body 37 has a plurality of bottomed holes 44 located on the inner peripheral side of the electromagnetic coil 39. The plurality of bottomed holes 44 are arranged at equal intervals in the circumferential direction of the stator main body 37. A coil spring 45 is built into each bottomed hole 44. The central axis of each coil spring 45 is along the axis P of the rotating shaft 15. The coil spring 45 is a biasing member that biases the brake armature 32.

[0025] The brake armature 32 faces the brake stator 31 in the axial direction P of the rotation axis 15. The brake armature 32 is disc-shaped, and the rotation axis 15 and the brake hub 34 penetrate through the central portion thereof. The brake armature 32 is movable in the axial direction P of the rotation axis 15. Further, one end of the coil spring 45 built in the brake stator 31 abuts on the brake stator 31 in the axial direction P, and the other end in the axial direction P protruding from the brake stator 31 abuts on the brake armature 32. The coil spring 45 biases the brake armature 32 in a direction away from the brake stator 31 along the axial direction of the rotation axis 15.

[0026] When the brake stator 31 is excited by energizing the electromagnetic coil 39, the brake armature 32 is attracted to the brake stator 31 against the biasing force of the coil spring 45. When the electromagnetic coil 39 is not energized and the brake stator 31 is not excited, the brake armature 32 moves in a direction away from the brake stator 31 under the biasing force of the coil spring 45.

[0027] The electromagnetic brake device 10 includes a disc-shaped fixing plate 33 fixed to the brake cover 36. The fixing plate 33 is positioned at a certain distance from the brake stator 31 along the axial direction of the rotation axis 15. The brake stator 31 and the fixing plate 33 are arranged side by side in the axial direction P of the rotation axis 15. The fixing plate 33 is fixed to the brake cover 36 by fastening a bolt (not shown) passing through the fixing plate 33 to the brake cover 36. The brake armature 32 is disposed between the brake stator 31 and the fixing plate 33 in the axial direction of the rotation axis 15.

[0028] The electromagnetic brake device 10 includes a brake hub 34 that rotates integrally with the rotating shaft 15. The brake hub 34 is keyed to the rotating shaft 15 and is non-rotatable in the circumferential direction with respect to the rotating shaft 15, but is slidable in the axial direction P of the rotating shaft 15. That is, the brake hub 34 is movable in the axial direction P of the rotating shaft 15. Key grooves (not shown) are formed in the axial direction on the outer peripheral surface of the rotating shaft 15 and the inner peripheral surface of the brake hub 34, and key fitting is achieved by inserting a key (not shown) into the key grooves. In FIG. 2, the slidable portion due to the key fitting between the brake hub 34 and the rotating shaft 15 is shown as a sliding portion S. The brake hub 34 is provided with a brake plate 35. The brake plate 35 is disc-shaped and is disposed between the brake armature 32 and the fixed plate 33 in the axial direction P of the rotating shaft 15. The brake plate 35 is fitted so as to be rotatable integrally with the brake hub 34 and is movable in the axial direction P of the rotating shaft 15. The plate surface of the brake plate 35 is provided with a friction material 46 that abuts against the brake armature 32 in the braking state and a friction material 47 that abuts against the fixed plate 33 in the braking state.

[0029] Next, the brake cover 36 will be described. The brake cover 36 includes a cover main body portion 48 fixed to the fixed plate 33, a side wall portion 49 extending from the periphery of the cover main body portion 48 to the brake stator 31, and a protruding portion 50 protruding axially from the cover main body portion 48. A through hole 48A through which a bolt 41 is inserted is provided near the outer periphery of the cover main body portion 48. The side wall portion 49 is a cylindrical portion that covers the outer peripheries of the brake armature 32, the brake plate 35, and the fixed plate 33. A space 51 for accommodating the end portion of the rotating shaft 15 is formed inside the protruding portion 50.

[0030] In the electromagnetic brake device 10 configured as described above, when the electromagnetic coil 39 is excited, the brake armature 32 is attracted to the brake stator 31, the brake armature 32 is separated from the brake plate 35, and the pressing of the brake plate 35 against the fixed plate 33 is released. As a result, the rotating shaft 15 is released from the braking state and can rotate freely without being restricted.

[0031] On the one hand, when the electromagnetic coil 39 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. Therefore, the brake plate 35 is sandwiched between the brake armature 32 and the fixed plate 33. As a result, the rotating shaft 15 is brought into a braking state by the frictional force generated between the brake armature 32 and the brake plate 35. That is, the parking brake is actuated.

[0032] By the way, the brake hub 34 is key-fitted to the rotating shaft 15 and is slidable in the axial direction of the axis P. At the other end of the rotating shaft 15, a retaining member 52 for preventing the brake hub 34 from coming off the rotating shaft 15 is fixed by a bolt 53. The retaining member 52 is a disk having an outer diameter larger than the outer diameter of the end portion of the rotating shaft 15. A through hole 54 through which the shaft portion of the bolt 53 is inserted is formed at the center of the retaining member 52.

[0033] One end face 55 of the retaining member 52 faces the end face of the brake hub 34, and the other end face 56 faces the protruding portion 50 of the brake cover 36. A ring-shaped buffer member 57 is fixed to one end face 55 of the retaining member 52. That is, the buffer member 57 is interposed between the brake hub 34 and the retaining member 52. The buffer member 57 is formed of an elastically deformable rubber-based material. In addition, the rubber-based material is preferably a material having resistance to wear, humidity, and salt. The fixing of the buffer member 57 to the retaining member 52 is fixed by an adhesive or a double-sided tape or the like.

[0034] The end face 57A of the buffer member 57 is the adhesive surface, and the end face 57B on the opposite side of the end face 57A faces the brake hub 34. As shown in FIG. 3, the buffer member 57 is a ring-shaped member and is arranged coaxially with the axis P of the rotating shaft 15. The diameter of the inner peripheral surface 57C of the buffer member 57 is larger than the outer peripheral diameter of the other end of the rotating shaft 15, and the diameter of the outer peripheral surface 57D of the buffer member 57 is smaller than the outer peripheral diameter of the brake hub 34 (see FIG. 2). The cross-sectional shape of the buffer member 57 is rectangular. The thickness of the buffer member 57 in the direction of the axis P is set to such a thickness that a slight gap G is formed between the buffer member 57 and the end face of the brake hub 34.

[0035] When the rotating shaft 15 rotates in the non-braking state, the brake hub 34 may move in the direction of the axis P with respect to the rotating shaft 15 and come into contact with the buffer member 57. Even when the buffer member 57 comes into contact with the brake hub 34, it absorbs the impact at the time of contact with the brake hub 34, and the generation of abnormal noise due to the contact is prevented. That is, the buffer member 57 has a function of preventing abnormal noise. Further, since the gap G between the buffer member 57 and the end face of the brake hub 34 is small, the buffer member 57 has a function of preventing foreign matter from entering the sliding portion S between the rotating shaft 15 and the brake hub 34.

[0036] Next, the operation of the electromagnetic brake device 10 of the present embodiment will be described. First, the case where the electromagnetic brake device 10 operates from the braking state to the non-braking state will be described. When the electromagnetic brake device 10 is in the braking state, the electromagnetic coil 39 is in a demagnetized state. Therefore, the brake armature 32 is pressed against the brake plate 35 by the biasing force of the coil spring 45. When the brake plate 35 is clamped between the brake armature 32 and the fixing plate 33, the braking force of the electromagnetic brake device 10 is generated.

[0037] When releasing the braking state of the electromagnetic brake device 10, the electromagnetic coil 39 is energized. When the electromagnetic coil 39 is energized and excited, the brake armature 32 is attracted to the brake stator 31 against the biasing force of the coil spring 45 by the attractive force of the magnetic force and separated from the brake plate 35. Then, the brake armature 32 is adsorbed to the brake stator 31.

[0038] When the electromagnetic brake device 10 is in a non-braking state, the rotor 12 of the electric motor 11 is rotatable. When the rotor 12 rotates, the rotating shaft 15 and the brake hub 34 are integrally rotated. Also, the retaining member 52 and the buffer member 57 rotate integrally with the rotating shaft 15. When the rotating shaft 15 and the brake hub 34 are integrally rotated, the brake hub 34 may slide in the axial direction of the axis P with respect to the rotating shaft 15 due to vibration or the like. When the brake hub 34 slides in the axial direction of the axis P toward the retaining member 52, the brake hub 34 abuts against the buffer member 57. Even when the brake hub 34 abuts against the buffer member 57, no abnormal noise due to the contact occurs due to the elastic deformation of the buffer member 57. Also, when the brake hub 34 abuts against the buffer member 57, the gap G is eliminated, preventing foreign matter from entering the sliding portion S between the rotating shaft 15 and the brake hub 34. Even when the brake hub 34 slides away from the buffer member 57, since the gap G is minute, it is difficult for foreign matter to enter the sliding portion S between the rotating shaft 15 and the brake hub 34.

[0039] Next, the case where the electromagnetic brake device 10 operates from a non-braking state to a braking state will be described. When the electromagnetic brake device 10 is in a non-braking state, the electromagnetic coil 39 is in an excited state. Therefore, the brake armature 32 is adsorbed to the brake stator 31 against the biasing force of the coil spring 45. When the brake armature 32 is adsorbed to the brake stator 31, no braking force is generated in the electromagnetic brake device 10.

[0040] When releasing the non-braking state of the electromagnetic brake device 10, the energization of the electromagnetic coil 39 is cut off. When the electromagnetic coil 39 is demagnetized due to the cut-off of the energization to the electromagnetic coil 39, the brake armature 32 is separated from the brake stator 31 by the biasing force of the coil spring 45 and pressed against the brake plate 35. Then, the brake plate 35 is tightly pressed by the brake armature 32 and the fixing plate 33. The electromagnetic brake device 10 enters the braking state.

[0041] The electromagnetic brake device 10 according to the present embodiment has the following effects. (1) Since the buffer member 57 is interposed between the brake hub 34 and the retaining member 52, the buffer member 57 does not contact the brake hub 34, and the generation of abnormal noise due to the contact is prevented. Further, the buffer member 57 interposed between the brake hub 34 and the retaining member 52 can prevent foreign matter from entering the sliding portion S between the brake hub 34 and the rotating shaft 15. That is, it is possible to prevent the generation of abnormal noise due to the contact between the brake hub 34 and the retaining member 52 and suppress the entry of foreign matter into the sliding portion S between the brake hub 34 and the rotating shaft 15. Further, since the brake hub 34 and the retaining member 52 do not contact each other, wear due to the contact between the brake hub 34 and the retaining member 52 can be prevented.

[0042] (2) The buffer member 57 is fixed to the end face 55 of the retaining member 52 that faces the end face of the brake hub 34, and a gap G is formed between the buffer member 57 and the brake hub 34. Therefore, even when the brake hub 34 has play in the circumferential direction with respect to the rotating shaft 15, the sliding contact between the buffer member 57 and the brake hub 34 can be suppressed due to the presence of the gap G between the buffer member 57 and the retaining member 52.

[0043] (3) The buffer member 57 is formed in a ring shape and is arranged coaxially with the rotating shaft 15. Therefore, the buffer member 57 surrounds the periphery of the rotating shaft 15, and can more effectively prevent foreign matter from entering the sliding portion S between the brake hub 34 and the rotating shaft 15.

[0044] (4) The buffer member 57 is formed of a rubber-based material. Therefore, even if the wear powder of the buffer member 57 enters the sliding portion S between the brake hub 34 and the rotating shaft 15 as foreign matter, the wear powder of the buffer member 57 is sufficiently soft compared to metal, and the sliding portion S between the brake hub 34 and the rotating shaft 15 is hardly affected by the wear powder of the buffer member 57. Further, by using the buffer member 57 made of a relatively inexpensive rubber-based material, the manufacturing cost can be suppressed.

[0045] (5) Since it is only necessary to fix the ring-shaped buffer member 57 to the retaining member 52, the number of necessary parts for preventing abnormal noise and suppressing the entry of foreign matter can be reduced as much as possible, and the assembling work of the electromagnetic brake device 10 is also relatively easy.

[0046] (Second Embodiment) Next, the electromagnetic brake device according to the second embodiment will be described. The electromagnetic brake device according to the second embodiment is different from the first embodiment in that the buffer member is attached to the rotor hub. In the present embodiment, the same configuration as that of the first embodiment is incorporated by reference to the description of the first embodiment, and common reference numerals are used.

[0047] As shown in FIG. 4, in the electromagnetic brake device 60 of the present embodiment, a buffer member 61 is fixed to the end face of the brake hub 34 facing the end face 55 of the retaining member 52 with an adhesive or double-sided tape. The shape of the buffer member 61 is the same as that of the buffer member 57 of the first embodiment. Therefore, the buffer member 61 includes an end face 61A facing the retaining member 52, an end face 61B on the opposite side of the end face 61A and serving as an adhesive surface, an inner peripheral surface 61C, and an outer peripheral surface 61D. The material of the buffer member 61 is a synthetic sponge obtained by foaming a synthetic resin. That is, the buffer member 61 is a sponge-like body. A slight gap G is formed between the buffer member 61 and the retaining member 52.

[0048] According to the present embodiment, effects equivalent to the effects (1) and (3) of the first embodiment are achieved. Further, the buffer member 61 is fixed to the end face of the brake hub 34 facing the retaining member 52, and a gap G is formed between the buffer member 61 and the retaining member 52. Therefore, even when the brake hub 34 has play in the circumferential direction with respect to the rotating shaft 15, the presence of the gap G can suppress the sliding contact between the buffer member 61 and the retaining member 52.

[0049] Further, the buffer member 61 is formed of synthetic sponge. Therefore, even if the wear powder of the buffer member 61 enters the sliding portion S between the brake hub 34 and the rotating shaft 15 as foreign matter, the wear powder of the buffer member 61 is sufficiently soft compared to metal, and the sliding portion S between the brake hub 34 and the rotating shaft 15 is hardly affected by the wear powder of the buffer member 61. In addition, since it is only necessary to fix the ring-shaped buffer member 61 to the retaining member 52, the number of necessary parts for preventing abnormal noise and suppressing the entry of foreign matter can be reduced as much as possible, and the assembly work of the electromagnetic brake device 60 becomes relatively easy. Furthermore, since the buffer member 61 is synthetic sponge, it absorbs moisture and can suppress the entry of moisture into the sliding portion S.

[0050] The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the gist of the invention. For example, the following modifications may be made.

[0051] ○ In the above embodiment, a gap is formed between the buffer member and the brake hub or the retaining member, but the present invention is not limited to this. For example, the buffer member and the brake hub or the retaining member may be in contact without a gap. ○ In the above embodiment, the buffer member is in a complete ring shape, but the present invention is not limited to this. For example, a notch may be formed in the buffer member to break it in the radial direction in the circumferential direction of the buffer member. Alternatively, the buffer member may be divided into a plurality of pieces, and the plurality of divided buffer members may be arranged in the circumferential direction. ○ In the above-described embodiment, the cross-sectional shape of the buffer member is rectangular, but it is not limited thereto. The cross-sectional shape may be, for example, circular or elliptical, or may be set to any free shape. ○ In the above-described embodiment, the rotating shaft and the brake hub are key-fitted, but it is not limited thereto. The brake hub may be, for example, spline-fitted to the rotating shaft. In this case, spline teeth may be formed on the outer peripheral surface of the rotating shaft in the axial direction, a spline hole may be formed in the brake hub in the axial direction, and the spline teeth may be inserted into the spline hole. ○ In the above-described embodiment, the retaining member is fixed to the rotating shaft by fastening a bolt, but the fixing of the retaining member to the rotating shaft is not limited to a bolt. The retaining member may be fixed to the rotating shaft by, for example, a snap ring, and the fixing means of the retaining member to the rotating shaft is not particularly limited.

Explanation of Reference Numerals

[0052] 10, 60 Electromagnetic Brake Device 11 Electric Motor 12 Rotor 13 Stator 15 Rotating Shaft 19 Output Side Bracket 21 Brake Side Bracket 31 Brake Stator 32 Brake Armature 33 Fixed Plate 34 Brake Hub 35 Brake Plate 36 Brake Cover 37 Stator Main Body 39 Electromagnetic Coil 41 Bolt 45 Coil Spring 52 Retaining Member 53 Bolt 57, 61 Buffer Member G Gap P Axis S Sliding Portion

Claims

1. A brake stator, a rotating shaft rotatable relative to the brake stator, a brake hub fitted to the rotating shaft and movable in the axial direction of the rotating shaft, a brake plate fitted to be integrally rotatable with the brake hub and provided to be movable in the axial direction of the rotating shaft, and a retaining member provided on the rotating shaft for preventing the brake hub from coming off the rotating shaft, in an electromagnetic brake device, wherein a buffer member is interposed between the brake hub and the retaining member.

2. The buffer member is fixed to an end face of the retaining member facing the brake hub, and a gap is formed between the buffer member and the brake hub. The electromagnetic brake device according to claim 1.

3. The buffer member is fixed to an end face of the brake hub facing the retaining member, and a gap is formed between the buffer member and the retaining member. The electromagnetic brake device according to claim 1.

4. The buffer member is formed in a ring shape and arranged coaxially with the rotating shaft. The electromagnetic brake device according to any one of claims 1 to 3.

5. The buffer member is formed of a rubber-based material or a spongy body. The electromagnetic brake device according to any one of claims 1 to 3.

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