Electromagnetic braking device

Abstract

An electromagnetic brake device (100) includes a brake hub (34) having an inner peripheral portion (34a) engaged with a rotation shaft (15) via a spline (15c) formed on a free end side of the rotation shaft (15) and supporting a brake plate (35), a stopper (10) fixed to the free end of the rotation shaft (15) to limit movement of the brake hub (34) to the free end side of the rotation shaft (15), and a cushion member (25) provided at a portion where the brake hub (34) and the stopper (10) face each other in a radial direction of the brake hub (34).

Description

Technical Field

[0001] This disclosure relates to electromagnetic braking devices. Background Technology

[0002] Previously, a technique for preventing abnormal noise was known by setting a buffer that suppresses the relative axial movement of the first rotating element and the second rotating element (see, for example, Patent Document 1). Existing technical documents Patent documents

[0003] Patent Document 1: Japanese Patent No. 6981182 Summary of the Invention The problem the invention aims to solve

[0004] As an example of an electromagnetic brake used as a parking brake in electric forklifts, there is a configuration in which the motor's rotating shaft is mounted relative to one end of the driving motor. In this configuration, the motor's rotating shaft is a free end and may vibrate in a direction orthogonal to the axial direction. As a result, in the part where the brake drum supporting the brake plate engages with the motor's rotating shaft via a spline fit, the brake drum and the rotating shaft may come into direct contact, causing abnormal noise.

[0005] The purpose of this disclosure is to provide an electromagnetic braking device that can prevent the rotating shaft, which engages with the brake hub via a spline formed on the free end side of the rotating shaft, from directly contacting the brake hub in a direction orthogonal to the axial direction of the rotating shaft. Solution for solving the problem

[0006] One aspect of this disclosure relates to an electromagnetic braking device comprising: 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 supporting a brake plate; a stop portion fixed to the free end of the rotating shaft to restrict movement of the brake hub toward the free end of the rotating shaft; and a buffer member disposed at the portions of the brake hub and the stop portion that are radially opposite to each other along the brake hub.

[0007] In one aspect of the electromagnetic braking device disclosed herein, a buffer member is provided at the radially opposite portion of the brake hub and the stop portion of the brake hub. Since the stop portion is fixed to the free end of the rotating shaft, the buffer member is located on the free end side of the rotating shaft, closer to the spline. Therefore, when the free end of the rotating shaft vibrates in a direction orthogonal to the axial direction of the rotating shaft, the buffer member is clamped by the brake hub and the stop portion before the brake hub directly contacts the rotating shaft at the spline. Thus, direct contact between the rotating shaft, which engages with the brake hub via the spline formed on the free end side of the rotating shaft, and the brake hub is prevented from directly contacting the brake hub in a direction orthogonal to the axial direction of the rotating shaft.

[0008] In one embodiment, the brake drum may have a recess for receiving a stop portion, and a buffer member may be disposed between the inner circumferential surface of the recess and the outer circumferential surface of the stop portion. In this case, the amount by which the stop portion protrudes axially relative to the brake drum toward the rotation axis can be suppressed, and the buffer member can be disposed using the space within the recess.

[0009] In one embodiment, the brake plate may be engaged via splines formed on the outer periphery of the brake drum. In this case, since splines exist at both the inner periphery of the brake drum and the rotating shaft, and the outer periphery of the brake drum and the brake plate, the brake drum is prone to play. Therefore, the effect of using a buffer member to suppress direct contact between the brake drum and the rotating shaft becomes significant.

[0010] Another aspect of this disclosure relates to an electromagnetic braking device comprising: 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 supporting a brake plate; a stop portion fixed to the free end of the rotating shaft to restrict movement of the brake hub toward the free end of the rotating shaft; and a buffer member disposed on an outer peripheral opposing surface of the rotating shaft located on the free end side of the spline, which is radially opposite to the brake hub.

[0011] In another aspect of the electromagnetic braking device disclosed herein, a buffer member is provided on the portion of the rotating shaft that is radially opposite to the brake hub on its outer peripheral opposing surface. Since the outer peripheral opposing surface is located on the free end side of the rotating shaft beyond the spline, the buffer member is positioned on the free end side of the rotating shaft beyond the spline. Therefore, when the free end of the rotating shaft vibrates in a direction orthogonal to the axial direction of the rotating shaft, the buffer member is clamped by the brake hub and the outer peripheral opposing surface before the brake hub directly contacts the rotating shaft at the spline. Thus, direct contact between the rotating shaft, which engages with the brake hub via the spline formed on the free end side of the rotating shaft, and the brake hub in a direction orthogonal to the axial direction of the rotating shaft can be prevented. Invention Effects

[0012] According to several aspects of this disclosure, it is possible to prevent the rotating shaft, which engages with the brake hub via a spline formed on the free end side of the rotating shaft, from directly contacting the brake hub in a direction orthogonal to the axial direction of the rotating shaft. Attached Figure Description

[0013] Figure 1 This is a partial cross-sectional view of the electric motor and the electromagnetic braking device according to the first embodiment. Figure 2 This is a longitudinal cross-sectional view of the main parts of the electromagnetic braking device according to the first embodiment. Figure 3 This is a longitudinal cross-sectional view of the main parts of the electromagnetic braking device according to the second embodiment. Figure 4 This is a longitudinal cross-sectional view of the main part of the electromagnetic braking device according to the third embodiment. Detailed Implementation

[0014] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Furthermore, in the drawings, the same or equivalent elements are labeled with the same reference numerals, and repeated descriptions are omitted.

[0015] [First Implementation] Figure 1 This is a partial cross-sectional view of the electric motor and the electromagnetic braking device according to the first embodiment. (See attached image.) Figure 1 As shown, the electromagnetic brake device 100 is provided relative to the electric motor 11. The electromagnetic brake device 100 is provided at one end 11b of the electric motor 11, which is opposite to one end 11a of the output shaft 23 described later.

[0016] The electric motor 11 is an electric motor used for driving vehicles, such as industrial vehicles like forklifts. The electric motor 11 has 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 stator coils 17. Coil ends 18 of the stator coils 17 are formed at both ends of the stator core 16 along the axial direction of the electric motor 11. Furthermore, in... Figure 1 In the example, the diagram shows the coil end 18 at one end of the stator core 16, while the diagram of the coil end 18 at the other end is omitted. An internal threaded hole 20 is formed at the center of the end of the rotating shaft 15 on the side of the electromagnetic brake device 100.

[0018] The electric motor 11 has an output side bracket 19 mounted to the stator 13 at end 11a and a brake side bracket 21 mounted to the stator 13 at end 11b along its axial direction. The output side bracket 19 and the brake side bracket 21 are connected by through bolts (not shown).

[0019] The output side bracket 19 supports the rotating shaft 15 on the end 11a side via a bearing (not shown) so that it can rotate. The end of the rotating 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 supports the rotating shaft 15 on the end 11b side via the bearing 22 so that it can rotate. The end 15a of the rotating shaft 15 on the end 11b side protrudes from the brake-side bracket 21 as the brake shaft 15b (rotating shaft).

[0021] Brake shaft 15b is a portion of rotating shaft 15 that protrudes axially outward from bearing 22 toward electric motor 11. Brake shaft 15b is supported by bearing 22 and extends in a cantilever beam shape from bearing 22 to end 15a. End 15a of brake shaft 15b corresponds to the "free end of rotating shaft 15". The portion of brake shaft 15b from bearing 22 to end 15a corresponds to the "free end side of rotating shaft 15".

[0022] The electromagnetic brake device 100 is configured as a parking brake for a vehicle, and is a non-excitation braking type electromagnetic brake device that achieves braking in a non-excitation state. The electromagnetic brake device 100 is mounted on the end face 21a of the brake-side bracket 21. The end face 21a is the end face on the side of the end 15a of the brake shaft 15b among the axial end faces of the brake-side bracket 21. The electromagnetic brake device 100 is configured to brake the rotation of the rotor 12.

[0023] Figure 2 This is a longitudinal cross-sectional view of the main parts of the electromagnetic braking device according to the first embodiment. (As shown...) Figure 2 As shown, the electromagnetic braking device 100 includes a braking stator 31, a braking armature 32, a fixing plate 33, a braking hub 34, and a braking plate 35.

[0024] The brake stator 31 has a stator body portion 37 disposed along the end face 21a of the brake side bracket 21. The stator body portion 37 is annular, and a circular hole 38 is formed in the center of the stator body portion 37. For example, the brake shaft 15b and a part of the brake hub 34 can be accommodated in the circular hole 38.

[0025] An annular electromagnetic coil 39, serving as an adsorption mechanism, is built into the stator body 37. The electromagnetic coil 39 energizes the braking stator 31 by receiving energization and de-energizes the braking stator 31 by stopping energization.

[0026] The stator body 37 has a through hole 42 for inserting a bolt 41. The bolt 41 is a fastening member for fixing the electromagnetic brake device 100 to the electric motor 11. The stator body 37 also has an internal threaded hole 62 for screwing in a bolt 61. Although details will be described later, the bolt 61 is a fastening member for fixing the fixing plate 33 to the brake stator 31. The brake-side bracket 21 has an internal threaded hole 43 for screwing in a bolt 41, which communicates with the through hole 42. The bolts 41, 61, the through hole 42, and the internal threaded holes 43 and 62 are... Figure 2The example only shows one set, but multiple sets can also be provided. The brake stator 31 is secured to the brake side bracket 21 by screwing the bolt 41, which passes through the through hole 42, into the internal threaded hole 43, and the electromagnetic brake device 100 is fixed to the electric motor 11. Bolts 41 and 61 are, for example, bolts with hexagonal holes. Bolt 41 can pass through the through hole 32a of the brake armature 32 and the through hole 33a of the fixing plate 33, and its head is tightened.

[0027] The stator body 37 has a plurality of bottomed holes 44 arranged at equal intervals along the circumference of the stator body 37. A helical spring 45 is housed within each of the bottomed holes 44. The helical spring 45 is a force-applying member that applies force to the brake armature 32. One axial end of the helical spring 45 abuts against the brake stator 31, and the other axial end abuts against the brake armature 32. The helical spring 45 applies a force to the brake armature 32 axially in a direction away from the brake stator 31.

[0028] The brake armature 32 is opposite to the brake stator 31 in the direction along the axis P of the rotation shaft 15 (hereinafter referred to as the "axial direction"). The brake armature 32 is in the shape of a circular plate, through which the brake shaft 15b and the brake hub 34 pass. The brake armature 32 is configured to be movable axially, for example, by inserting a bolt 61 into a cylindrical distance collar 64 disposed in a U-shaped groove 32b that is U-shaped when viewed axially. By abutting the distance collar 64 against the inner wall surface of the U-shaped groove 32b in the circumferential direction, the circumferential movement of the brake armature 32 is restricted within a certain range.

[0029] The fixing plate 33 is axially positioned on the side opposite to the brake stator 31 with respect to the brake armature 32. The fixing plate 33 is circular, with the brake hub 34 passing through its central portion. For example, when the fixing plate 33 abuts against the brake stator 31 via the spacer 64, a bolt 61 is inserted through the through hole 33b. By being clamped by the head of the bolt 61 and the spacer 64, the fixing plate 33 is fixed axially at a position where the axial distance between it and the brake stator 31 is a predetermined distance, and circumferentially, the fixing plate 33 is integrally fixed to the brake stator 31.

[0030] The electromagnetic braking device 100 includes a brake hub 34 supporting a brake plate 35. The brake hub 34 has an inner peripheral portion 34a that serves as a through hole for insertion of a brake shaft 15b. A spline 15c is formed on the brake shaft 15b from its end 15a toward the bearing 22 within a defined range. A spline 34b, capable of engaging with the spline 15c, is formed, for example, axially along the entire inner peripheral portion 34a of the brake hub 34. The spline 34b and spline 15c are configured to engage with each other. The brake hub 34 is inserted while the spline 34b of the inner peripheral portion 34a engages with the spline 15c of the brake shaft 15b, thus engaging with the brake shaft 15b. That is, 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. Although the brake hub 34, which is splinedly engaged with the brake shaft 15b, rotates integrally with the brake shaft 15b in the circumferential direction, it can slide relative to the brake shaft 15b in the axial direction and move relative to it. The brake hub 34 can slide relative to the brake shaft 15b within the extension range of the spline 15c.

[0031] The brake plate 35 is a circular plate-shaped component disposed axially between the brake armature 32 and the fixed plate 33 on the brake shaft 15b. Friction members 46, which abut against the brake armature 32 in the braking state, and friction members 47, which abut against the fixed plate 33 in the braking state, are fixed on the surface of the brake plate 35.

[0032] The brake plate 35 has an inner peripheral portion 35a through which the brake hub 34 is inserted. In the brake hub 34, a spline 34e is formed within a predetermined range from the end 34d in the outer peripheral portion 34c of the brake hub 34. A spline 35b, capable of engaging with the spline 34e, is formed, for example, along the axial direction of the inner peripheral portion 35a of the brake plate 35. The spline 34e and spline 35b are configured to engage with each other. The brake plate 35 is inserted while the spline 35b of the inner peripheral portion 35a engages with the spline 34e of the brake hub 34, thus engaging with the brake hub 34. That is, the brake plate 35 is engaged via the spline 34e formed in the outer peripheral portion 34c of the brake hub 34. Although the brake plate 35, spline-engaged with the brake hub 34, rotates integrally with the brake hub 34 in the circumferential direction, it can slide relative to the brake hub 34 in the axial direction and move relative to it. The brake plate 35 can slide relative to the brake drum 34 within the range between the brake armature 32 and the fixed plate 33.

[0033] In the electromagnetic braking device 100 configured in this way, when the electromagnetic coil 39 is energized by energizing it, the brake armature 32 overcomes the force of the helical spring 45 and is attracted to the brake stator 31. The brake armature 32 moves away from the brake plate 35, and the pressure of the brake plate 35 on the fixed plate 33 is released. As a result, the brake shaft 15b is not braked, and the rotating shaft 15 can rotate because it is no longer subject to frictional forces from the brake armature 32 and the brake plate 35, and from 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 magnetically excited, the brake armature 32 is pressed towards the brake plate 35 by the force applied by the helical spring 45, and the brake plate 35 is pressed against the fixed plate 33. The brake plate 35 is clamped between the brake armature 32 and the fixed plate 33. As a result, friction is generated between the brake armature 32 and the brake plate 35, and between the brake plate 35 and the fixed plate 33, the rotating shaft 15 is braked, and the parking brake is activated.

[0035] A stop portion 10 is provided at the end 15a of the brake shaft 15b. The stop portion 10 prevents the brake hub 34, which is spline-fitted with the brake shaft 15b, from moving axially from the brake shaft 15b and disengaging from it. The stop portion 10 is fixed to the end 15a of the brake shaft 15b, for example, by a bolt 24. In this embodiment, the stop portion 10 is a cylindrical member with an outer diameter larger than that of the end 15a of the brake shaft 15b. A shaft portion through which a bolt 24 is inserted is inserted into a through hole at the center of the stop portion 10.

[0036] The brake hub 34 has a recess 36 for receiving the stop portion 10. The recess 36 is formed, for example, as a bottomed hole defining a cylindrical space. One end face 10a of the stop portion 10 is axially spaced apart from the bottom surface of the recess 36 of the brake hub 34 by a predetermined interval. Therefore, the brake hub 34 can move axially in the brake shaft 15b between one end face 10a of the stop portion 10 and the end portion on the bearing 22 side of the spline 15c. That is, the stop portion 10 is fixed to the end 15a (the free end of the rotating shaft 15) of the brake shaft 15b, restricting the 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 stop portion 10. A predetermined gap is formed in the radial direction between the inner circumferential surface 36a of the recess 36 of the brake hub 34 and the outer circumferential surface 10b of the stop portion 10. Through this gap, the brake hub 34 and the stop portion 10 are opposite each other in the radial direction of the brake hub 34.

[0038] A buffer member 25 is provided at the portion of the brake drum 34 and the stop portion 10 that are radially opposite each other along the brake drum 34. The buffer member 25 is a member used to suppress abnormal noise from the brake drum 34. The abnormal noise from the brake drum 34 may be caused, for example, by the free end of the brake shaft 15b or by the radial vibration of the brake drum 34 itself.

[0039] In this embodiment, a buffer member 25 is provided in the gap between the inner peripheral surface 36a of the recess 36 formed in the brake drum 34 and the outer peripheral surface 10b of the stop portion 10. The buffer member 25 can be, for example, an O-ring. A plurality of (e.g., two) grooves 10c are provided on the outer peripheral surface 10b of the stop portion 10, and the buffer member 25 is embedded in each of these grooves 10c. The radially predetermined interval of the gap between the inner peripheral surface 36a and the outer peripheral surface 10b can, for example, be the same as the radial dimension of the buffer member 25. The buffer member 25 is, for example, formed of an elastically deformable rubber-based material with a circular cross-section. For example, when the gap between the inner peripheral surface 36a and the outer peripheral surface 10b becomes narrower than the predetermined interval, the buffer member 25 abuts against both the brake drum 34 and the stop portion 10 in an elastically deformable manner, and the buffer member 25 can be in a clamped state. The axial dimension of the stop portion 10 is, for example, the thickness corresponding to the number of buffer members 25, and may be the thickness to the extent that it does not protrude from the recess 36 of the brake drum 34.

[0040] Here, since the brake shaft 15b becomes a free end, it may vibrate in a direction orthogonal to the axial direction. When the free end of the brake shaft 15b vibrates in a direction orthogonal to the axial direction of the brake shaft 15b, relative displacement between the brake hub 34 and the brake shaft 15b may occur, such as making the gap between the inner circumferential surface 36a and the outer circumferential surface 10b narrower than the specified interval. As a result, in the part where the brake hub 34 supporting the brake plate 35 and the brake shaft 15b are engaged by spline fitting, the brake hub 34 and the brake shaft 15b may come into direct contact, causing abnormal noise.

[0041] In this regard, in the electromagnetic braking device 100, a buffer member 25 is provided at the portion of the brake hub 34 and the stop portion 10 that are radially opposite each other along the brake hub 34. Since the stop portion 10 is fixed to the end 15a of the brake shaft 15b, which is the free end of the rotation shaft 15, the buffer member 25 is located in the brake shaft 15b at a position closer to the end 15a (free end side) than the spline 15c. Therefore, when the brake shaft 15b vibrates in a direction orthogonal to the axial direction of the brake shaft 15b, the buffer member 25 is clamped by the brake hub 34 and the stop portion 10 before the brake hub 34 directly contacts the brake shaft 15b at the spline 15c. That is, the buffer member 25 abuts against both the brake hub 34 and the stop portion 10. The buffer member 25 creates a gap between the inner circumferential surface 36a and the outer circumferential surface 10b, corresponding to the elastically deformed buffer member 25. This reduces the amplitude of vibration at the free end of the brake shaft 15b in a direction orthogonal to the axial direction of the brake shaft 15b. Therefore, direct contact between the brake shaft 15b, which engages with the brake drum 34 via the spline 15c formed on the free end side of the brake shaft 15b, and the brake drum 34 in a direction orthogonal to the axial direction of the brake shaft 15b can be suppressed. Furthermore, the buffer member 25 can also suppress direct contact between the brake drum 34 and the stop portion 10. However, as a result of the elastic deformation of the buffer member 25, direct contact between the brake drum 34 and the stop portion 10 is also possible. In this case, the amplitude of vibration at the free end of the brake shaft 15b can be reduced in the same way as described above.

[0042] In the electromagnetic braking device 100, the brake drum 34 has a recess 36 for receiving the stop portion 10. A buffer member 25 is disposed between the inner peripheral surface 36a of the recess 36 of the brake drum 34 and the outer peripheral surface 10b of the stop portion 10. With this configuration, the amount by which the stop portion 10 protrudes axially relative to the brake drum 34 toward the rotation axis 15 can be suppressed, and the buffer member 25 is disposed within the space of the recess 36.

[0043] In the electromagnetic braking device 100, the brake plate 35 is engaged via splines 34e formed on the outer periphery 34c of the brake hub 34. In this configuration, splines are present at two locations: the spline 15c between the inner periphery 34a of the brake hub 34 and the brake shaft 15b, and the spline 34e between the outer periphery 34c of the brake hub 34 and the brake plate 35. Therefore, the brake hub 34 is prone to play. Thus, the effect of the buffer member 25 in preventing direct contact between the brake hub 34 and the brake shaft 15b becomes significant.

[0044] [Second Implementation] Next, the electromagnetic braking device according to the second embodiment will be described. The electromagnetic braking device 100A according to the second embodiment differs from the electromagnetic braking device 100 in that the buffer member 25A is mounted on the brake shaft 15d instead of the stop portion. Hereinafter, for configurations that are the same as those in the first embodiment, the description of the first embodiment will be referenced and the same reference numerals will be used.

[0045] Figure 3 This is a longitudinal cross-sectional view of the main parts of the electromagnetic braking device according to the second embodiment. (See diagram below.) Figure 3 As shown, in the brake shaft 15d, as an example, a small diameter portion 15e is formed within a specified range from the end 15a toward the bearing 22, and a spline 15c is formed within a specified range from the end portion of the small diameter portion 15e on the bearing 22 side toward the bearing 22. The small diameter portion 15e is set to have a smaller diameter than the diameter of the portion of the brake shaft 15d where the spline 15c is formed at the end 15a side (free end side) compared to the spline 15c.

[0046] In the inner circumference 34a of the brake hub 34A, a spline 34b is formed on the portion of the spline 15c of the brake shaft 15d that forms axially, capable of engaging with the spline 15c. The end 34d side of the inner circumference 34a of the brake hub 34A is provided as an inner circumferential diameter portion 34f that extends radially inward, corresponding to the small diameter portion 15e of the brake shaft 15d. The outer circumferential surface of the small diameter portion 15e of the brake shaft 15d faces the inner circumferential diameter portion 34f of the brake hub 34A at a point on the free end side of the brake shaft 15d compared to the spline 15c. Therefore, the small diameter portion 15e is the outer circumferential facing surface of the brake shaft 15d located on the free end side compared to the spline 15c.

[0047] A buffer member 25A is provided in the gap between the inner circumferential diameter portion 34f of the brake hub 34A and the small diameter portion 15e of the brake shaft 15d. Specifically, the buffer member 25A is provided in the portion of the brake shaft 15d that is located on the side of the small diameter portion 15e (free end side) closer to the end 15a of the spline 15c and is radially opposite to 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 embedded in this groove 15f. The radial interval of the gap can, for example, be the same as the radial dimension of the buffer member 25A.

[0048] Furthermore, in the electromagnetic braking device 100A, the stop portion 40 can also be a diameter ratio of Figure 2 The stop part 10 is a small-diameter disc.

[0049] In the electromagnetic braking device 100A, a buffer member 25A is provided on the portion of the brake shaft 15d where the small-diameter portion 15e (outer peripheral opposing surface) and the brake hub 34A are radially opposite each other. Since the small-diameter portion 15e is located on the end 15a side (free end side) of the brake shaft 15d, closer to the spline 15c, the buffer member 25A is positioned on the end 15a side of the brake shaft 15d. Therefore, when the end 15a of the brake shaft 15d vibrates in a direction orthogonal to the axial direction of the brake shaft 15d, the buffer member 25A is clamped between the brake hub 34A and the small-diameter portion 15e before the brake hub 34A directly contacts the brake shaft 15d at the spline 15c. 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 prevent direct contact between the brake shaft 15d and the brake hub 34A in a direction orthogonal to the axial direction of the brake shaft 15d.

[0050] [Third Implementation] Next, the electromagnetic braking device according to the third embodiment will be described. The electromagnetic braking device 100B according to the third embodiment has a buffer member 25B provided on the outer side of the brake drum 34B and in the part where the stop portion 50 is located (the inner peripheral side of the stop portion), which is different from the electromagnetic braking device 100 which has a buffer member 25 provided on the inner side of the brake drum 34 and in the part where the stop portion 10 is located (the outer peripheral side of the stop portion).

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

[0052] As an example, the stop portion 50 has a base 51 fixed to the end 15a of the brake shaft 15b, an opposing portion 52 covering the protrusion 34g of the brake hub 34B, and a connecting portion 53 connecting the base 51 to the opposing portion 52. The base 51 is a disc-shaped portion of a size that allows the bolt 24 to be seated. The opposing portion 52 extends axially outward from the radially outer side of the outer peripheral surface 34h of the protrusion 34g of the brake hub 34B. The outer peripheral surface 34h of the protrusion 34g of the brake hub 34B faces the opposing portion 52, which is the inner peripheral surface of the stop portion 50, at the free end side of the brake shaft 15b compared to the spline 15c. The connecting portion 53 includes, for example, a cylindrical portion 53a that stands axially from the outer peripheral portion of the base 51, and a circular plate portion 53b that connects the end of the cylindrical portion 53a to the end of the opposing portion 52.

[0053] A buffer member 25B is provided in the gap between the opposing portion 52 of the stop portion 50 and the protrusion 34g of the brake hub 34B. Specifically, the buffer member 25B is provided in the portion of the brake shaft 15b that is located on the side of the stop portion 50 near the end 15a (free end side) of the spline 15c, and the brake hub 34B is radially opposite to each other. The buffer member 25B can be, for example, an O-ring. A groove 52a is provided in the opposing portion 52 of the stop portion 50, and the buffer member 25B is embedded in this groove 52a. The radial interval of the gap can, for example, be the same as the radial dimension of the buffer member 25B.

[0054] In the electromagnetic braking device 100B, similarly to the electromagnetic braking device 100, when the brake shaft 15b vibrates in a direction orthogonal to the axial direction of the brake shaft 15b, the brake hub 34B and the stop portion 50 clamp the buffer member 25B before the brake hub 34B directly contacts the brake shaft 15b at the spline 15c. Therefore, direct contact between the brake shaft 15b, which engages with the brake hub 34B via the spline 15c formed on the free end side of the brake shaft 15b, and the brake hub 34B is prevented from directly contacting the brake shaft 15b in a direction orthogonal to the axial direction of the brake shaft 15b.

[0055] [Variation Example] The above describes the implementation methods involved in this disclosure, but this disclosure is not limited to the above-described implementation methods.

[0056] In the above embodiments, brake hubs 34, 34A, and 34B have recesses 36 for receiving stop portions 10, 40, and 50, but are not limited to this example. Recesses 36 may also be omitted.

[0057] In the above embodiments, the brake plate 35 is engaged via a spline 34e formed on the outer periphery 34c of the brake hub 34, but this is not limited to this example. The brake plate 35 and the brake hub 34 can also be fixed by methods other than splines, such as fastening with bolts or rivets.

[0058] In the above embodiments, grooves for inserting buffer members are formed on the inner peripheral 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 stop portion 50, but this is not limited to this example. Grooves may also be formed on the inner peripheral surface 36a of the recess 36 of the brake hub 34, the inner peripheral diameter portion 34f of the brake hub 34A, and the outer peripheral surface 34h of the protrusion 34g of the brake hub 34B.

[0059] In the above embodiments, the portions of the brake drum and the stop portion that are opposite each other along the radial direction of the brake drum are provided as surfaces parallel to the axial direction, but they may also be conical surfaces inclined relative to the axial direction.

[0060] In the second embodiment described above, the small-diameter portion 15e of the brake shaft 15d is exemplified as the outer peripheral opposing surface, but it is not limited to this example. For example, it could also be an outer peripheral opposing surface with an outer diameter the same as the valley portion of the spline 15c and without a spline.

[0061] In the above embodiments, rubber O-rings are exemplified as buffer members, but the method is not limited to this. The buffer member can also be a bushing made of resin such as Duracon. Furthermore, the buffer member may not be annular; it can be discretely arranged radially along the brake drum at the portions opposite each other on the brake drum and the stop. Additionally, the cross-sectional shape of the buffer member is not limited to a circle; it can be a triangle or the like, gradually tapering outwards radially. When the cross-sectional shape of the buffer member is gradually tapering, the braking torque is less likely to be transmitted from the brake drum to the stop via the buffer member, thus preventing the bolt 24 from loosening due to the braking torque. Industrial availability

[0062] According to several aspects of this disclosure, it is possible to prevent the rotating shaft, which engages with the brake hub via a spline formed on the free end side of the rotating shaft, from directly contacting the brake hub in a direction orthogonal to the axial direction of the rotating shaft. Explanation of reference numerals in the attached figures

[0063] 10, 40, 50…stop section, 10b…outer peripheral surface, 15…rotating shaft, 15b…brake shaft (rotating shaft), 15c, 34b, 34e, 35b…spline, 15e…small diameter section (outer peripheral opposing surface), 25, 25A, 25B…buffer component, 34, 34A, 34B…brake hub, 34a…inner peripheral section, 34c…outer peripheral section, 34h…outer peripheral surface, 35…brake plate, 35a…inner peripheral section, 36…recess, 36a…inner peripheral surface, 100, 100A, 100B…electromagnetic braking device.

Claims

1. An electromagnetic braking device, characterized in that, have: A brake hub having an inner periphery that engages with the rotating shaft via a spline formed on the free end side of the rotating shaft, and supporting a brake plate; A stop portion, which is fixed to the free end of the rotating shaft, restricts the movement of the brake hub toward the free end side of the rotating shaft; as well as A buffer member is disposed on the portion of the brake hub and the stop portion that are radially opposite to each other along the brake hub.

2. The electromagnetic braking device according to claim 1, wherein, The brake hub has a recess for receiving the stop portion. The buffer member is disposed between the inner peripheral surface of the recess of the brake hub and the outer peripheral surface of the stop portion.

3. The electromagnetic braking device according to claim 1 or 2, wherein, The brake plate is engaged via splines formed on the outer periphery of the brake hub.

4. An electromagnetic braking device, characterized in that, have: A brake hub having an inner periphery that engages with the rotating shaft via a spline formed on the free end side of the rotating shaft, and supporting a brake plate; A stop portion, which is fixed to the free end of the rotating shaft, restricts the movement of the brake hub toward the free end side of the rotating shaft; as well as A buffer member is provided on the outer peripheral opposing surface of the rotating shaft, which is located on the side of the spline closer to the free end, and is opposite to the brake hub along the radial direction of the brake hub.

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