JP7694441B2 - Electromagnetic Brake Device - Google Patents

Description

This invention relates to an electromagnetic brake device.

As a conventional 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 comprises a movable iron core, a rotating disk, a center hub, a rotating shaft, and a connecting member. The movable iron core is movable only in the axial direction, being attracted by the electromagnet to release the brake and being pushed by the brake spring to apply the brake. The rotating disk is disposed between the movable iron core and the brake plate. The center hub is connected to the rotating disk so that it can move 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 brake plate.

The non-excitation electromagnetic brake device of Patent Document 1 also includes a movement restriction means between the center hub or rotating shaft and the rotating disk, which restricts the movement distance of the rotating disk from the braking position in the release direction to a position smaller than the gap from the braking position of the movable iron core to the release position, and a biasing means that biases the rotating disk in the release direction with a force smaller than the force of the brake spring.

According to the non-excitation electromagnetic brake device of Patent Document 1, when the rotating disk is released and rotating, the axial position of the rotating disk is determined by the movement restriction means and the biasing means between the movable iron core in the released position and the brake plate, so that the rotating disk does not slide against either the movable iron core or the brake plate, and no sliding noise is generated.

Japanese Patent Application Publication No. 7-35175

In some electromagnetic brake devices, a brake hub (center hub) is provided that is axially slidable relative to the rotating shaft. In this case, a retaining member is provided at the end of the rotating shaft to prevent the brake hub from coming off the rotating shaft. When the rotating shaft is rotating, i.e., when not braking, the brake hub may slide axially and repeatedly come into contact with the retaining member. This causes problems such as abnormal noise when the brake hub comes into contact with the retaining member, and foreign matter is likely to get in between the brake hub and the rotating shaft. If metal powder (foreign matter) gets in between the brake hub and the rotating shaft, wear is accelerated at the sliding portion between the brake hub and the rotating shaft.

In the non-excitation electromagnetic brake device of Patent Document 1, the movement distance of the rotating disk in the release direction is merely used to restrict the sliding of the movable iron core and the brake plate and suppress the generation of sliding noise, and is not a technology to suppress abnormal noise when the brake hub and the retaining member come into contact.

The present invention was made in consideration of the above problems, and the object of the present invention is to provide an electromagnetic brake device that can prevent the generation of abnormal noise when the brake hub and the retaining member come into contact and can also prevent the intrusion of foreign objects.

In order to solve the above problems, the present invention provides an electromagnetic brake device having 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 the brake hub so as to be rotatable together with the brake hub and movable in the axial direction of the rotating shaft, and a retaining member provided on the rotating shaft to prevent the brake hub from coming off the rotating shaft, the device being characterized in that a buffer member is interposed between the brake hub and the retaining member.

In the present invention, a buffer member is interposed between the brake hub and the retaining member, so that the buffer member does not come into contact with the brake hub or the retaining member, preventing the generation of abnormal noise due to contact. In addition, 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.

In the above electromagnetic brake device, the buffer member may be fixed to an end surface of the retaining member that faces 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 face of the retaining member that faces the brake hub, and a gap is formed between the buffer member and the brake hub. Therefore, even if there is wobble in the brake hub in the circumferential direction relative to the rotating shaft, the existence of the gap makes it possible to suppress sliding contact between the buffer member and the brake hub.

In the above electromagnetic brake device, the buffer member may be fixed to an end face of the brake hub that faces the anti-slip member, and a gap may be formed between the buffer member and the anti-slip member.
In this case, the buffer member is fixed to the end face of the brake hub that faces the retaining member, and a gap is formed between the buffer member and the retaining member. Therefore, even if the brake hub wobbles in the circumferential direction relative to the rotating shaft, the existence of the gap between the buffer member and the retaining member can suppress sliding contact between the buffer member and the retaining member.

In the above electromagnetic brake device, the buffer member may be formed in a ring shape and disposed coaxially with the rotating shaft.
In this case, the buffer member is formed in a ring shape and disposed coaxially with the rotating shaft, so that the buffer member surrounds the periphery of the rotating shaft, thereby making it possible to more effectively prevent foreign matter from entering the sliding portion between the brake hub and the rotating shaft.

In the electromagnetic brake device described above, the buffer member may be made of a rubber material or a spongy material.
Since the cushioning member is formed from a rubber-based material or a spongy body, even if wear powder from the cushioning 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.

The present invention provides an electromagnetic brake device that can prevent the generation of abnormal noise when the brake hub and the retaining member come into contact and can also prevent the intrusion of foreign objects.

1 is a side view showing an electromagnetic brake device and an electric motor according to a first embodiment, with a portion cut away; 1 is a longitudinal sectional view of a main portion of an electromagnetic brake device according to a first embodiment of the present invention; FIG. 4 is a perspective view of a retaining member and a buffer member of the electromagnetic brake device. FIG. 11 is a longitudinal sectional view of a main portion of an electromagnetic brake device according to a second embodiment.

(First embodiment)
An electromagnetic brake device according to a first embodiment will be described below with reference to the drawings. The electromagnetic brake device of this embodiment is a non-excitation braking type electromagnetic brake device that is in a braking state when not excited. The electromagnetic brake device of this embodiment is an electromagnetic brake device provided on an electric motor for driving mounted on a vehicle, and the vehicle is a forklift as an industrial vehicle.

As shown in FIG. 1, the electromagnetic brake device 10 of this 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 includes 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 ends 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 in the center of the end of the rotating shaft 15 that faces the electromagnetic brake device 10.

The electric motor 11 includes an output side bracket 19 attached to one end of the stator 13, and a brake side bracket 21 attached to the other end of the stator 13, which is the electromagnetic brake device 10 side. The output side bracket 19 rotatably supports one end of the rotating shaft 15 via a bearing (not shown). The brake side bracket 21 rotatably supports 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 the output shaft 23. The 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.

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

Next, we will explain the electromagnetic brake device 10 that can brake the rotation of the rotor 12. As shown in Figure 2, the electromagnetic brake device 10 has a brake stator 31, a brake armature 32, a fixed plate 33, a brake hub 34, a brake plate 35, and a brake cover 36.

As shown in FIG. 2, the brake stator 31 has a ring-shaped stator body 37 and a circular hole 38 in the center of the stator body 37. One end face of the stator body 37 abuts against the brake side bracket 21. The circular hole 38 accommodates the other end of the rotating shaft 15 and a part of the brake hub 34. The stator body 37 has a ring-shaped electromagnetic coil 39 built in as an attraction mechanism. The electromagnetic coil 39 excites the brake stator 31 when current is applied, and de-excites the brake stator 31 when current is cut off.

The stator body 37 has through holes 42 through which bolts 41 for fixing the electromagnetic brake device 10 to the electric motor 11 are inserted, and the brake side bracket 21 has threaded holes 43 that face the through holes 42 and allow the bolts 41 to be screwed in. The brake stator 31 is fixed to the brake side bracket 21 by threading the bolts 41 inserted into the through holes 42 into the threaded holes 43. The multiple bolts 41 pass through the brake armature 32 and the fixing plate 33, respectively, and fix the brake stator 31 to the electric motor 11.

The stator body 37 has a number of bottomed holes 44 located on the inner circumferential side of the electromagnetic coil 39. The bottomed holes 44 are arranged at equal intervals in the circumferential direction of the stator body 37. Coil springs 45 are built into the bottomed holes 44. The central axis of each coil spring 45 is aligned with the axis P of the rotating shaft 15. The coil springs 45 are biasing members that bias the brake armature 32.

The brake armature 32 faces the brake stator 31 in the direction of the axis P of the rotating shaft 15. The brake armature 32 is disk-shaped, and the rotating shaft 15 and the brake hub 34 pass through the center. The brake armature 32 is movable in the direction of the axis P of the rotating shaft 15. In addition, one end of a coil spring 45 built into the brake stator 31 in the direction of the axis P abuts against the brake stator 31, and the other end in the direction of the axis P protruding from the brake stator 31 abuts against the brake armature 32. The coil spring 45 biases the brake armature 32 in the axial direction of the rotating shaft 15 away from the brake stator 31.

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 receives the biasing force of the coil spring 45 and moves in a direction away from the brake stator 31.

The electromagnetic brake device 10 includes a disk-shaped fixed plate 33 fixed to a brake cover 36. The fixed plate 33 is located a certain distance away from the brake stator 31 along the axial direction of the rotating shaft 15. The brake stator 31 and the fixed plate 33 are arranged side by side in the direction of the axis P of the rotating shaft 15. The fixed plate 33 is fixed to the brake cover 36 by fastening a bolt (not shown) that passes through the fixed plate 33 to the brake cover 36. The brake armature 32 is disposed between the brake stator 31 and the fixed plate 33 in the axial direction of the rotating shaft 15.

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 cannot rotate in the circumferential direction relative to the rotating shaft 15, but can slide in the axial direction P of the rotating shaft 15. In other words, the brake hub 34 can move in the axial direction P of the rotating shaft 15. A key groove (not shown) is formed in the axial direction on the outer circumferential surface of the rotating shaft 15 and the inner circumferential surface of the brake hub 34, and a key (not shown) is inserted into the key groove to achieve key engagement. In FIG. 2, the portion that can slide due to the key engagement 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. It is engaged with the brake hub 34 so as to be able to rotate integrally with the brake hub 34 and can move in the axial direction P of the rotating shaft 15. The plate surface of the brake plate 35 is provided with friction material 46 that contacts the brake armature 32 when braking, and friction material 47 that contacts the fixed plate 33 when braking.

Next, the brake cover 36 will be described. The brake cover 36 comprises a cover body 48 fixed to the fixed plate 33, a side wall 49 extending from the periphery of the cover body 48 to the brake stator 31, and a protrusion 50 protruding in the axial direction from the cover body 48. A through hole 48A through which the bolt 41 is inserted is provided near the outer periphery of the cover body 48. The side wall 49 is a cylindrical portion that covers the outer periphery of the brake armature 32, the brake plate 35, and the fixed plate 33. A space 51 is formed inside the protrusion 50 to accommodate the end of the rotating shaft 15.

In the electromagnetic brake device 10 configured in this manner, 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 brake plate 35 is released from the pressing force against the fixed plate 33. As a result, the rotating shaft 15 is released from the braked state and can rotate freely without restriction.

On the other hand, when the electromagnetic coil 39 is not excited, the force of the coil spring 45 presses the brake armature 32 toward the brake plate 35, 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 frictional force generated between the brake armature 32 and the brake plate 35 brakes the rotating shaft 15. In other words, the parking brake is activated.

The brake hub 34 is key-fitted to the rotating shaft 15 and can slide in the direction of the axis P. A retaining member 52 that prevents the brake hub 34 from slipping out of the rotating shaft 15 is fixed to the other end of the rotating shaft 15 with a bolt 53. The retaining member 52 is a disk with an outer diameter larger than the outer diameter of the end of the rotating shaft 15. A through hole 54 is formed in the center of the retaining member 52, through which the shaft of the bolt 53 is inserted.

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. In other words, the buffer member 57 is interposed between the brake hub 34 and the retaining member 52. The buffer member 57 is made of an elastically deformable rubber-based material. The rubber-based material is preferably a material that is resistant to abrasion as well as humidity and salt. The buffer member 57 is fixed to the retaining member 52 with an adhesive or double-sided tape, etc.

The end surface 57A of the buffer member 57 is the adhesive surface, and the end surface 57B opposite to the end surface 57A faces the brake hub 34. As shown in FIG. 3, the buffer member 57 is a ring-shaped member, but 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 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 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 axis P direction is set to a thickness such that a small gap G is formed between the buffer member 57 and the end surface of the brake hub 34.

When the rotating shaft 15 rotates in a non-braked state, the brake hub 34 may move in the direction of the axis P relative to the rotating shaft 15 and come into contact with the buffer member 57. Even if the buffer member 57 comes into contact with the brake hub 34, it absorbs the impact when it comes into contact with the brake hub 34, preventing the generation of abnormal noise due to the contact. In other words, the buffer member 57 has the function of preventing abnormal noise. In addition, 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 the function of preventing foreign matter from entering the sliding portion S between the rotating shaft 15 and the brake hub 34.

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

When the braking state of the electromagnetic brake device 10 is to be released, current is passed through the electromagnetic coil 39. When the electromagnetic coil 39 is excited by the passage of current through the electromagnetic coil 39, the brake armature 32 is attracted to the brake stator 31 against the biasing force of the coil spring 45 by the magnetic attraction force, and is separated from the brake plate 35. The brake armature 32 is then attracted to the brake stator 31.

When the electromagnetic brake device 10 is in a non-braking state, the rotor 12 of the electric motor 11 can rotate. When the rotor 12 rotates, the rotating shaft 15 and the brake hub 34 rotate together. In addition, the retaining member 52 and the buffer member 57 rotate together with the rotating shaft 15. When the rotating shaft 15 and the brake hub 34 rotate together, the brake hub 34 may slide in the axial direction P relative to the rotating shaft 15 due to vibrations, etc. When the brake hub 34 slides in the axial direction P toward the retaining member 52, the brake hub 34 abuts against the buffer member 57. Even if the brake hub 34 abuts against the buffer member 57, no abnormal noise due to the abutment is generated due to the elastic deformation of the buffer member 57. In addition, the gap G is eliminated by the brake hub 34 abutting against the buffer member 57, and foreign matter is prevented from entering the sliding portion S between the rotating shaft 15 and the brake hub 34. Even if the brake hub 34 slides away from the buffer member 57, the gap G is so small that foreign matter is unlikely to enter the sliding area S between the rotating shaft 15 and the brake hub 34.

Next, a 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 excited. Therefore, the brake armature 32 is attracted to the brake stator 31 against the biasing force of the coil spring 45. As the brake armature 32 is attracted to the brake stator 31, no braking force is generated in the electromagnetic brake device 10.

To release the electromagnetic brake device 10 from the non-braking state, the electromagnetic coil 39 is de-energized by de-energizing 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 is pressed against the brake plate 35. The brake plate 35 is then pressed between the brake armature 32 and the fixed plate 33. The electromagnetic brake device 10 is put into a braking state.

The electromagnetic brake device 10 according to this embodiment provides the following advantages.
(1) Since the buffer member 57 is interposed between the brake hub 34 and the retaining member 52, the buffer member 57 does not come into contact with the brake hub 34, preventing the generation of abnormal noise due to the contact. In addition, 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. In other words, 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 to suppress the intrusion of foreign matter into the sliding portion S between the brake hub 34 and the rotating shaft 15. In addition, since the brake hub 34 and the retaining member 52 do not come into contact with each other, wear due to the contact between the brake hub 34 and the retaining member 52 can be prevented.

(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 if the brake hub 34 wobbles in the circumferential direction relative to the rotating shaft 15, the existence of the gap G between the buffer member 57 and the retaining member 52 can suppress sliding contact between the buffer member 57 and the brake hub 34.

(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 better prevent foreign matter from entering the sliding portion S between the brake hub 34 and the rotating shaft 15.

(4) The buffer member 57 is made of a rubber-based material. Therefore, even if wear particles from the buffer member 57 enter the sliding portion S between the brake hub 34 and the rotating shaft 15 as foreign matter, the wear particles from the buffer member 57 are 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 particles from the buffer member 57. In addition, by using a relatively inexpensive rubber-based material for the buffer member 57, the manufacturing cost can be reduced.

(5) Since it is only necessary to fix the ring-shaped buffer member 57 to the retaining member 52, the number of parts required to prevent abnormal noise and to prevent the intrusion of foreign objects can be reduced as much as possible, and the assembly work of the electromagnetic brake device 10 is also relatively easy.

Second Embodiment
Next, an electromagnetic brake device according to a second embodiment will be described. The electromagnetic brake device according to the second embodiment differs from the first embodiment in that a buffer member is attached to a rotor hub. In this embodiment, the same configuration as in the first embodiment will be described with reference to the first embodiment, and common reference numerals will be used.

As shown in FIG. 4, in the electromagnetic brake device 60 of this embodiment, a buffer member 61 is fixed with adhesive or double-sided tape to the end face of the brake hub 34 that faces the end face 55 of the retaining member 52. 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 has an end face 61A that faces the retaining member 52, an end face 61B that is opposite the end face 61A and is an adhesive face, 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. In other words, the buffer member 61 is a spongy body. A small gap G is formed between the buffer member 61 and the retaining member 52.

This embodiment provides the same effects as the effects (1) and (3) of the first embodiment. In addition, the buffer member 61 is fixed to the end face of the brake hub 34 that faces the retaining member 52, and a gap G is formed between the buffer member 61 and the retaining member 52. Therefore, even if there is wobble in the brake hub 34 in the circumferential direction relative to the rotating shaft 15, the presence of the gap G makes it possible to suppress sliding contact between the buffer member 61 and the retaining member 52.

The buffer member 61 is also made of synthetic sponge. Therefore, even if wear particles of the buffer member 61 enter the sliding portion S between the brake hub 34 and the rotating shaft 15 as foreign matter, the wear particles of the buffer member 61 are 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 particles 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 parts required to prevent abnormal noise and prevent the intrusion of foreign matter can be reduced as much as possible, and the assembly work of the electromagnetic brake device 60 is also relatively easy. Furthermore, since the buffer member 61 is made of synthetic sponge, it absorbs moisture and can prevent moisture from entering the sliding portion S.

The present invention is not limited to the above embodiment, and various modifications are possible within the scope of the invention. For example, the following modifications may be made:

In the above embodiment, a gap is formed between the buffer member and the brake hub or the retaining member, but this is not limited to the above. For example, the buffer member and the brake hub or the retaining member may be in contact with each other without any gap.
In the above embodiment, the buffer member is a complete ring-shaped member, but is not limited thereto. For example, the buffer member may have a notch formed in the circumferential direction thereof to break the buffer member in the radial direction. Alternatively, the buffer member may be divided into a plurality of pieces, and the divided buffer members may be arranged in the circumferential direction.
In the above embodiment, the cross-sectional shape of the buffer member is rectangular, but is not limited to this. The cross-sectional shape may be, for example, circular or elliptical, or may be any other shape.
In the above embodiment, the rotating shaft and the brake hub are key-fitted together, but this is not limited to this. The brake hub may be spline-fitted to the rotating shaft, for example. In this case, spline teeth may be formed in the axial direction on the outer circumferential surface of the rotating shaft, 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 embodiment, the retaining member is fixed to the rotating shaft by fastening the bolt, but the method of fixing the retaining member to the rotating shaft is not limited to the bolt. The retaining member may be fixed to the rotating shaft by, for example, a snap ring, and the means of fixing the retaining member to the rotating shaft is not particularly limited.

Reference Signs List 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 Anti-dislodgement member 53 Bolt 57, 61 Buffer member G Gap P Shaft center S Sliding portion

Claims (5)

A brake stator;
A rotating shaft rotatable relative to the brake stator;
a brake hub that is fitted to the rotating shaft and is movable in an axial direction of the rotating shaft;
a brake plate that is fitted to the brake hub so as to be rotatable together with the brake hub and that is movable in an axial direction of the rotating shaft;
a retaining member provided on the rotating shaft to prevent the brake hub from coming off the rotating shaft,
An electromagnetic brake device, characterized in that a buffer member is interposed between the brake hub and the retaining member. The buffer member is fixed to an end surface of the retaining member that faces the brake hub,
2. An electromagnetic brake device according to claim 1, wherein a gap is formed between said buffer member and said brake hub. The buffer member is fixed to an end surface of the brake hub that faces the retaining member,
2. An electromagnetic brake device according to claim 1, wherein a gap is formed between said buffer member and said retaining member. An electromagnetic brake device according to any one of claims 1 to 3, characterized in that the buffer member is formed in a ring shape and is arranged coaxially with the rotating shaft. An electromagnetic brake device according to any one of claims 1 to 3, characterized in that the buffer member is made of a rubber-based material or a sponge-like material.

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