JP2008106883A - Torque limiter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a torque limiter with an inexpensive structure, which provides stable and large load torque regardless of its small size, is easily assembled, and has fewer part items. <P>SOLUTION: The magnetic torque limiter includes: a center shaft member which has a cylindrical surface; and a cylindrical permanent magnet having an inside diameter larger than the outside diameter of the center shaft member and arranged concentrically with the center shaft member, and is also provided with a short cylindrical hysteresis member which has: a center hole having a diameter smaller than the outside diameter of the cylindrical surface of the center shaft member; and a pair of annular planes extending vertically with respect to the center shaft member, and which is rotated together with the center shaft member with an inner peripheral part in the vicinity of the center hole buried into the center shaft member. The permanent magnet is arranged at a predetermined minute distance with respect to one or both surfaces of the annular planes of the hysteresis member. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a magnetic torque limiter formed by combining a cylindrical permanent magnet and an annular plate hysteresis member.

  The torque limiter is generally arranged between the driving side and the driven side in the rotation mechanism of the paper feeding, transporting, and discharging portion of a printer such as an OA device, a copying machine, and the driving side in a normal load state that is not overloaded. Power is transmitted to the driven side, and when an overload occurs on the driven side, a slip operation is performed to prevent the overload from being transmitted to the drive side. Most of the torque limiters are contact type that is caused by mechanical friction because of low cost, but the price is high, but the non-contact type has advantages such as semi-permanent life and maintenance free. Magnetic torque limiters are also being used in many devices.

Various applications have been filed and improved for the magnetic torque limiter. In such a torque limiter, a cylindrical magnet is used as a permanent magnet. However, the thickness of the cylindrical magnet is limited in terms of downsizing and cost, and therefore the cylindrical magnet has a certain degree of mechanical strength. There is a problem that it is broken when subjected to an impact or external force. As a torque limiter having a structure that solves this problem, an annular plate-like hysteresis member is attached to the central shaft member via a bearing, and a short cylindrical permanent magnet having a relatively thick wall is attached to the central shaft member. Some are fixed (see, for example, Patent Document 1). As is well known, in this magnetic torque limiter, the magnetic force acts between the hysteresis member coupled to the load side and the permanent magnet. Although it rotates together with the central shaft member, if an overnegative torque exceeding the set torque value is applied, a slip phenomenon occurs between the permanent magnet and the hysteresis member, and the load torque between them becomes almost the set torque. Maintained. In other words, in the overload state, the hysteresis member coupled to the load side does not rotate, but the central shaft member coupled to the drive device such as a motor and the permanent magnet rotate, so that the drive device is overloaded. prevent.
JP-A-6-60488

  In a torque limiter with a relatively large or large load torque, the set torque is set to a large value. As described above, when an overload condition occurs, the load torque approximately equal to the set torque is Since it is applied between the members, a large force is applied between the permanent magnet and the central shaft member. Therefore, in the case of a torque limiter with medium / high load torque, the permanent magnet and the central shaft member must be firmly fixed to each other. However, since a permanent magnet with a plurality of magnetic poles is made of a brittle magnetic material with lower mechanical strength than steel, etc., it is practically difficult to press the central shaft member into the permanent magnet with a large force. Another fixing member such as a stop member is used, and the permanent magnet is firmly fixed to the central shaft member by the member. Therefore, the invention of the aforementioned Patent Document 1 requires a specific member such as a detent member, and there is a problem that the cost increases because the number of parts increases and the assembly becomes complicated. In any case, since the permanent magnet must be firmly fixed to the central shaft member with a non-rotating member or the like, the anti-rotating member or the like has a structure that reduces the force per unit area by dispersing the force applied to the permanent magnet. Therefore, there is a problem in miniaturizing the torque limiter.

  The present invention provides a torque limiter having an inexpensive structure that can obtain a stable, relatively large or large load torque despite being thin and small in the axial direction, and that is easy to assemble and has a small number of components. The main purpose is to do.

  In order to solve the above-mentioned problem, the first invention provides a cylindrical central shaft member, a cylindrical hysteresis member engaged with the central shaft member, and a center having a diameter larger than the outer diameter of the central shaft member. The torque limiter includes a cylindrical permanent magnet that has a hole and is arranged concentrically with the central shaft member. The hysteresis member extends in a direction perpendicular to the central hole and the central shaft member. An annular plane, and is engaged with the central shaft member and rotates together with the central shaft member, and the hysteresis member is spaced a predetermined distance from one or both sides of the annular plane. Provided is a torque limiter in which a cylindrical permanent magnet is arranged.

  According to a second invention, there is provided the torque limiter according to the first invention, wherein the central shaft member is made of a synthetic resin material having good heat conduction.

  A third invention provides a torque limiter according to the first invention or the second invention, wherein the central shaft member has a small hole or a small groove for heat dissipation extending in the axial direction.

  According to a fourth invention, in any one of the first invention to the third invention, an outer ring engaged with the central hole of the permanent magnet and an inner ring engaged with an outer peripheral surface of the central shaft member. And a spacer member for adjusting the predetermined distance between a side surface of the permanent magnet and the annular plane of the hysteresis member, and the hysteresis member and the radial bearing. The torque limiter is provided, wherein the spacer member has an outer diameter equal to or smaller than an inner diameter of the outer ring of the radial bearing.

  A fifth invention is the first annular member according to any one of the first invention to the third invention, wherein the hysteresis member rotates in parallel with each other around the central shaft member on one side or both sides of the hysteresis member. And a second annular member, comprising a thrust type bearing disposed between the hysteresis member and the permanent magnet, wherein the first annular member comprises the center member. Provided is a torque limiter which is engaged with a shaft member, wherein the second annular member is attracted to the permanent magnet and is not in contact with the central shaft member.

  According to a sixth invention, in the fifth invention, a spacer member for adjusting the predetermined distance between the hysteresis member side of the permanent magnet and the annular plane of the hysteresis member is provided with the hysteresis member and the thrust. A torque limiter is provided, wherein the spacer member has an outer diameter equal to or less than an outer diameter of the first annular member of the thrust type bearing.

  According to a seventh invention, in any one of the first invention to the sixth invention, an annular metal plate is in contact with a side surface of the permanent magnet opposite to the hysteresis member side, An annular metal plate provides a pre-torque limiter characterized by acting as a back yoke and side plates.

  According to an eighth invention, in any one of the first invention to the seventh invention, an outer peripheral surface of the cylindrical permanent magnet is covered with a synthetic resin, and a plurality of the permanent magnets are provided with the hysteresis. The permanent magnets are arranged on both sides of the annular plane of the member, and the permanent magnets are connected by a connecting member or a housing through the synthetic resin, and the outer peripheral surface of the hysteresis member is not in contact with the connecting member or the housing. A torque limiter is provided.

  According to the first aspect of the present invention, when the central shaft member serving as the inner ring member is formed by molding with a resin material, the hysteresis plate is made perpendicular to the central shaft member by embedding the inner peripheral portion of the hysteresis plate in the resin material together. Because it is firmly fixed and integrated, it can sufficiently handle a large load torque, and other components can be assembled based on the central shaft member and hysteresis plate, making it easy to assemble the torque limiter It is. Furthermore, since the short cylindrical permanent magnet is attached to the central shaft member via the bearing and almost no force is applied between the permanent magnet and the outer ring of the bearing, the outer ring of the bearing is permanently attached to the central hole of the permanent magnet. If it press-fits with the force which does not have a bad influence on a magnet, those fixed strength will be enough, workability | operativity will be good, and a reliable torque limiter can be provided. Furthermore, the hysteresis member can be positioned with high accuracy with respect to the central shaft member, and this can manage a small set gap between the hysteresis member and the permanent magnet.

  According to the second invention, in addition to the effects obtained by the first invention, since a synthetic resin material having good thermal conductivity is used, it is easy to mold an insert mold and the like during operation. It is possible to suppress the temperature rise of the torque limiter.

  According to the third invention, in addition to the effects obtained by the first invention or the second invention, the temperature rise of the central shaft member can be further suppressed, so that the torque limiter is heated during operation. The rise can be further suppressed, and the thermal adverse effect on the permanent magnet can be further suppressed.

  According to the fourth aspect of the invention, in addition to the effects obtained by the first to third aspects, a radial bearing is used for mechanical coupling between the central shaft member and the permanent magnet that do not apply load torque. Therefore, it is only necessary to lightly press the outer ring of the bearing into the permanent magnet, and there is no adverse effect such as damage to the permanent magnet. In addition, since a spacer member for adjusting a predetermined minute distance between the permanent magnet and the hysteresis member is provided, the dimensional control of the radial type bearing is not strictly performed, and the gap between the side surface of the permanent magnet and the hysteresis member is maintained. Can be easily managed at a predetermined minute distance.

  According to the fifth invention, in addition to the effects obtained by the first to third inventions, the first annular member and the second member that rotate with each other via a rolling element such as a ball. Using a thrust-type bearing composed of an annular member, the first annular member is firmly pressed into the central shaft member, and the permanent magnet is attracted and held on the second annular member by the magnetic attraction force of the permanent magnet. Therefore, it is not necessary to apply pressure to the permanent magnet by press fitting, and the permanent magnet can be attached to the central shaft member without applying pressure to the permanent magnet. Further, the magnetic characteristics of the permanent magnet are not changed.

  According to the sixth invention, in addition to the effects obtained by the fifth invention, the spacer member for adjusting a predetermined minute distance between the permanent magnet and the hysteresis member is provided. Therefore, it is possible to easily manage the distance between the side surface of the permanent magnet and the hysteresis member at a predetermined minute distance without performing the dimension management. In the case of a thrust type bearing, it is relatively easy to make the thickness almost the set value. In this case, the spacer member can be omitted.

  According to the seventh invention, in addition to the effects obtained by the first to sixth inventions, an annular metal plate made of a magnetic material is brought into contact with the outer side surface of the permanent magnet, and the back Since it acts as a yoke and a side plate, the number of component parts can be reduced, as well as downsizing, assembling becomes easy, and cost can be reduced.

  According to the eighth invention, in addition to the effects obtained by the first invention to the seventh invention, the outer peripheral surface of the cylindrical permanent magnet is covered with the synthetic resin, and the synthetic resin is interposed therebetween. Since the permanent magnets are connected by the connecting member or the housing, the permanent magnets are not damaged by the mechanical force due to the connection, and the permanent magnets are not displaced from each other. Further, since the outer peripheral surface of the hysteresis member is not in contact with the connecting member or the housing, no extra mechanical force is applied when the hysteresis member rotates, and the set torque can be easily obtained.

[Embodiment 1]
A magnetic torque limiter 100 according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view showing components before assembly of the torque limiter 100, and FIG. 2 is a cross-sectional view showing a cross section of the torque limiter 100. FIG. 3 is a partially enlarged view for explaining the relationship between the spacer and the bearing. FIG. 4 is an enlarged view of a part of the torque limiter. Here, an example of a torque limiter that is suitable for a medium / high load torque having a relatively large load torque or a large load torque will be described.

  This torque limiter 100 includes a central shaft member 1 acting as an inner ring member, a hysteresis member 2 in which an inner peripheral portion is embedded in the central shaft member 1 at the time of molding, and a cylindrical permanent magnet disposed on both sides of the permanent magnet with a minute gap therebetween. 3 and 4, and radial type bearings 5 and 6 that attach the permanent magnets 3 and 4 to the central shaft member 1 so as to be rotatable, and a minute amount between the hysteresis member 2 and the permanent magnets 3 and 4 that are mounted on the central shaft member 1. The spacer members 7 and 8 that adjust and hold the gap to the set value, the outer peripheral members 9 and 10 that cover the outer peripheral surfaces of the cylindrical permanent magnets 3 and 4, and the outer peripheral members 9 and 10 are prevented from rotating against each other. It comprises a connecting member 11 that acts and metal plates 12 and 13 that are attached so as to be attracted to the outer side surfaces of the cylindrical permanent magnets 3 and 4.

  1 to 4, the central shaft member 1 acting as an inner ring member is manufactured by insert molding or the like, and the inner peripheral portion of the hysteresis member 2 is molded together at the time of molding, and the inner peripheral portion is formed on the central shaft member 1. Embedded and firmly fixed. The central shaft member 1 is made of synthetic resin having good thermal conductivity, for example, 10 or more thermal conductive fillers selected from graphite particles, alumina particles, aluminum carbide, silicon carbide, carbon fibers and the like as thermal conductive fillers. It is preferably made of a synthetic resin having a good thermal conductivity, such as a polyphenylene sulfide resin or a phenol molding resin contained in an amount of from% to several tens%.

  The center shaft member 1 is a cylindrical member having a center hole 1A through which a drive shaft to which a rotation shaft of a rotation drive motor (not shown) is coupled is inserted, and has a predetermined thickness having a required mechanical strength. The drive shaft includes an attachment portion 1B for attaching the central shaft member 1 by a pin member (not shown). As shown in FIG. 2, the hysteresis member 2 is an annular plate having a central hole 2 </ b> A having a diameter W smaller than the outer diameter D of the central shaft member 1 and larger than the inner diameter d of the central shaft member 1. And made of a magnetic material having a large holding force such as a pure iron material or a permalloy material. In the hysteresis member 2, when the central shaft member 1 is manufactured by insert molding or the like, the inner peripheral portion 2 </ b> B around the central hole 2 </ b> A is molded together and embedded in the central shaft member 1. The hysteresis member 2 has a pair of mutually parallel annular planes 2 </ b> C and 2 </ b> D (FIG. 3) perpendicular to the central axis X of the central shaft member 1. Therefore, the central shaft member 1 and the hysteresis member 2 can be handled as one integrated part, which is convenient not only when assembling the torque limiter but also because they are firmly fixed to each other. Can withstand torque sufficiently. The central shaft member 1 may be a columnar shaft rod that does not have the central hole 1A, and any outer peripheral surface may be a cylindrical surface.

  Cylindrical permanent magnets 3 and 4 are made of neodymium bonded magnets that can be easily molded with high productivity, low cost, and high magnetic force, or magnetic materials such as ferrite or samarium, and the magnetic materials are limited. It is not something. Cylindrical permanent magnets 3 and 4 are, like normal magnets, an equal number of alternating and opposite polarities, for example 5 or 6 pairs of N, divided approximately equally by a line extending radially outward from the center thereof. It has a pole and an S pole. Cylindrical permanent magnets 3 and 4 are aligned so as to face each other with the same polarity through hysteresis member 2 and are connected so that they do not deviate from each other as will be described later. The cylindrical permanent magnets 3 and 4 are attached to the central shaft member 1 by radial bearings 5 and 6, respectively. Further, the annular inner side surfaces 3A and 4A (FIG. 3) of the cylindrical permanent magnets 3 and 4 are connected to the annular planes 2C and 2D of the hysteresis member 2 through a minute gap formed by the spacer members 7 and 8. Are parallel to each other.

  3 and 4 showing a partially enlarged view, the radial bearing 5 includes an inner ring 5A into which the central shaft member 1 is press-fitted, and an outer ring 5B into which the center hole 3B of the permanent magnet 3 is lightly press-fitted, It is a very general one comprising a rolling element 5C composed of a plurality of balls or rollers that roll between an inner ring 5A and an outer ring 5B. The radial type bearing 6 has the same structure as the radial type bearing 5, and an inner ring 6A into which the central shaft member 1 is press-fitted, an outer ring 6B that is lightly press-fitted into the central hole 4B of the permanent magnet 4, and a plurality of rolling elements 6C. It consists of. Here, the radial bearings 5 and 6 have the same width (in the direction in which the central axis X in FIG. 2 extends), and the inner side surfaces 3A and 4A of the permanent magnets 3 and 4 are inside the radial bearings 5 and 6, respectively. Although it is desirable that the side surfaces 3A and 4A are substantially in the same vertical plane, the inner side surfaces 3A and 4A of the permanent magnets 3 and 4 protrude somewhat from the inner side surfaces 5a and 6a of the radial bearings 5 and 6. I do not care. The central axis X is an axis extending in the length direction through the central point of the circular cross section of the cylindrical surface of the central shaft member 1.

  Both surfaces of the annular plate-like spacer member 7 attached to the central shaft member 1 are in contact with the annular plane 2C of the hysteresis member 2 and the inner side surface 5a of the inner ring 5A of the radial bearing 5, and the annular plate Both surfaces of the spacer member 8 are in contact with the annular plane 2D of the hysteresis member 2 and the inner side surface 6a of the inner ring 6A of the radial bearing 6. The annular plate-like spacer members 7 and 8 have outer diameters smaller than the inner diameters of the outer rings 5B and 6B of the radial bearings 5 and 6, respectively, and smaller inner diameters than the outer diameters of the inner rings 5A and 6A. Since the spacer members 7 and 8 do not come into contact with the outer rings 5B and 6B of the radial bearings 5 and 6, respectively, the spacer members 7 and 8 abut against the inner side surface 5a of the inner ring 5A and the inner side surface 6a of the inner ring 6A. The gap between the permanent magnet 3 and the gap between the hysteresis member 2 and the permanent magnet 4 can be maintained at a set minute interval. In order to reduce the magnetic loss, the gap between the annular plane 2C of the hysteresis member 2 and the inner side surface 3A of the permanent magnet 3 and the gap between the annular plane 2D of the hysteresis member 2 and the inner side surface 4A of the permanent magnet 4 are set. It should be kept as small and constant as possible. Therefore, in the first embodiment, a plurality of thin annular metal plates having a thickness in the range of 10 to 100 μm are used as the spacer members 7 and 8 to form and hold a predetermined gap. For example, when the gap between the annular plane 2C of the hysteresis member 2 and the inner side surface 3A of the permanent magnet 3 and the gap between the annular plane 2D of the hysteresis member 2 and the inner side surface 4A of the permanent magnet 4 are each 0.3 mm, By stacking six annular metal plates having a thickness of 50 μm as the spacer members 7 and 8, the spacer can be easily adjusted to a predetermined gap and the gap can be maintained.

  The outer peripheral surfaces of the cylindrical permanent magnets 3 and 4 are covered with outer peripheral members 9 and 10 made of a synthetic resin that can also serve as a housing member. The synthetic resin preferably has good thermal conductivity. The outer peripheral members 9 and 10 are formed so as to wrap around the outer peripheral portions of the cylindrical permanent magnets 3 and 4 by molding such as insert molding. The outer peripheral members 9 and 10 have the same structure. As shown in an enlarged view in FIG. 4, the outer peripheral members 9 and 10 have engaging portions SA formed of recesses on one side surface of the outer peripheral portion, but the engaging portions of the outer peripheral member 9 are shaded. Not shown. These engaging portions SA receive the engaging portions 11A and 11B made of protrusions formed on both sides of an annular connecting member 11 made of a metal material or a plastic material, and engage with each other. Further, the other side of the outer peripheral members 9 and 10, that is, the outer side surface is formed so as to protrude from the side surfaces of the cylindrical permanent magnets 3 and 4. It has the latching | locking part UB which latches. The locking portion UB is formed in an uneven shape on the inner surface of a short cylindrical portion formed so as to protrude from the outer side surfaces of the permanent magnets 3 and 4. Since the engaging portions 11A and 11B of the connecting member 11 are formed at five locations, the engaging portions SA of the outer peripheral members 9 and 10 are also formed at five locations on one side of each of the outer peripheral members 9 and 10. . However, the number of the engaging portions 11A and 11B of the connecting member 11 and the engaging portions SA of the outer peripheral members 9 and 10 is arbitrary and is not limited to the shape, and the permanent magnets 3 and 4 are engaged. Thus, it is only necessary to prevent the permanent magnets 3 and 4 from shifting in the rotational direction.

  In the first embodiment, annular metal plates 12 and 13 are provided on the outer side surfaces of the cylindrical permanent magnets 3 and 4. The metal plates 12 and 13 act as back yokes that enhance the yoke effect of the permanent magnets 3 and 4, suppress magnetic leakage, and also serve as general side plates of the torque limiter. The metal plates 12 and 13 have center holes 12A and 13A having a diameter larger than the outer diameter of the central shaft member 1, and the outer periphery of the metal plates 12 and 13 is uneven as shown in FIG. The engaging portions 12B, 13B made of the unevenness engage with engaging portions UB formed on the outer side of the outer peripheral members 9, 10. The metal plates 12 and 13 are attracted to the outer side surfaces of the cylindrical permanent magnets 3 and 4 by magnetic force, but the respective locking portions 12B and 13B are engaged with the engaging portions UB of the outer peripheral members 9 and 10. By doing so, the permanent magnets 3 and 4 are rotated together with the permanent magnets 3 and 4 and the outer peripheral members 9 and 10 without being shifted or detached in the rotational direction. 1 and 4, the coupling member 14 fixed to the metal plate 13 is a coupling member to which a load device (not shown) is coupled.

  Next, the operation of the torque limiter will be briefly described. When a normal load, that is, a rotational driving force equal to or less than a set load torque is applied to the central shaft member 1, the annular plate-like hysteresis member 2 in which the inner peripheral portion is embedded in the central shaft member 1 rotates together. Since the cylindrical permanent magnets 3 and 4 are attracted to the hysteresis member 2 by their large magnetic force, the permanent magnets 3 and 4 rotate together with the central shaft member 1 and the hysteresis member 2. Since the outer peripheral members 9 and 10 are fixed to the outer periphery of the permanent magnets 3 and 4 and rotate together and are connected to each other by the connecting member 11, they rotate together without being displaced from each other in the rotation direction. Naturally, since the metal plates 12 and 13 also rotate together, a load (not shown) coupled to the coupling member 14 also rotates. That is, the rotational force on the drive side is transmitted to the load side as it is.

  However, when an external force larger than the set torque value is applied to the load side and an overload state is caused, the permanent magnets 3 and 4 side to which a load (not shown) is coupled, that is, the permanent magnets 3 and 4, the connecting member 11, and the metal plate 12 are connected. , 13 cannot rotate, and only the central shaft member 1 and the hysteresis member 2 rotate. Accordingly, at this time, a torque having a predetermined value is generated between the hysteresis member 2 and the permanent magnets 3 and 4 by the magnetic force. Therefore, the driving device (not shown) coupled to the central shaft member 1 generates the torque having the predetermined value. Since the rotating operation is performed as a load torque, it does not burn out due to overload. Since radial bearings 5 and 6 are interposed between the central shaft member 1 and the permanent magnets 3 and 4, respectively, it is inconvenient between the central shaft member 1 and the permanent magnets 3 and 4 even during an overload. Power is not applied.

  In the first embodiment described above, the outer peripheral members 9 and 10 are provided on the outer periphery of the permanent magnets 3 and 4, and these are connected by the connecting member 11, and these are used as the housing. However, as shown in FIG. In the modification 100 ′ in which the torque limiter 100 is partially changed, a single housing member 20 is provided, and the outer peripheral surfaces of the cylindrical permanent magnets 3 and 4 are in close contact with the inner peripheral surface of the housing member 20, that is, press-fitted. . The rest of the structure is the same as that described above, and a description thereof will be omitted. In FIG. 6, the same symbols as those used in FIG. 2 indicate members having the same names. The outer appearance of the housing member 20 is cylindrical, and a large-diameter portion having a large inner diameter so as not to contact the outer peripheral surface of the hysteresis member 2 at the inner central portion thereof, that is, the inner portion where the hysteresis member 2 is located when assembled. 20A is formed. Further, the both end portions of the housing member 20 have engaging portions UB that engage with the engaging portions of the metal plates 12 and 13. As shown by the broken line Z, the cylindrical outer peripheral surfaces of the permanent magnets 3 and 4 are undulated when viewed from the left or right direction in FIG. By forming the peripheral surface into a corrugated shape, the concavities and convexities may be fitted to each other so that the cylindrical permanent magnets 3 and 4 are prevented from rotating. In this case, it is only necessary to apply a slight force to the permanent magnets 3 and 4, and an excessively large pressing force is not applied to the permanent magnets 3 and 4 at the time of assembly, so that they are not damaged.

[Embodiment 2]
A magnetic second torque limiter 200 according to the second embodiment of the present invention will be described with reference to FIGS. 6 and 7, the same symbols as those used in FIGS. 1 to 5 indicate members having the same names. The second torque limiter 200 is different from the first torque limiter 100 in that the first torque limiter 100 uses radial ball bearings as the bearings 5 and 6, whereas the second torque limiter 200 uses the second torque limiter 200. The main difference is that thrust bearings 50 and 60 are used as the bearings. Since the parts other than those related to the bearings are almost the same, the description thereof is omitted.

  The radial type bearings 5 and 6 used in the first torque limiter 100 are suitable to receive a force in a direction perpendicular to the central axis X of the central shaft member 1, that is, in the radial direction. The mold bearings 50 and 60 are suitable for receiving a force in the same direction (parallel direction) as the central axis X of the central shaft member 1, that is, in the axial direction. FIG. 7 shows the thrust bearings 50 and 60, a part of the hysteresis member 2 in the vicinity thereof, and a part of the central shaft member 1 in an enlarged manner, which will be described with reference to FIG. Similarly to the first torque limiter 100, the second torque limiter 200 reduces the magnetic loss, the gap between the annular plane 2C of the hysteresis member 2 and the inner side surface 3A of the permanent magnet 3, and the hysteresis member 2 It is preferable to keep the gap between the annular plane 2D and the inner side surface 4A of the permanent magnet 4 as small and constant as possible.

  The cylindrical permanent magnets 3 and 4 in the second torque limiter 200 have the same structure. In the permanent magnet 3, the inner peripheral surface facing the outer peripheral surface of the central shaft member 1 has a large diameter surface. 3C and a small-diameter surface 3D having a small diameter. Similarly, in the permanent magnet 4, the inner peripheral surface facing the outer peripheral surface of the central shaft member 1 is composed of a large-diameter surface 4C having a large diameter and a small-diameter surface 4D having a small diameter. . The recessed side surface 3E between the large diameter surface 3C and the small diameter surface 3D and the recessed side surface 4E between the large diameter surface 4C and the small diameter surface 4D are annular planes substantially perpendicular to the central axis X. is there. Thrust-type bearings 50 and 60 are disposed on the large diameter portion formed by the large diameter surface 3C and the side surface 3E and the large diameter portion formed by the large diameter surface 4C and the side surface 4E, respectively. The thrust type bearings 50 and 60 have the same structure. The large-diameter surface 3C and the small-diameter surface 3D of the permanent magnet 3 form the central hole 3B, and the large-diameter surface 4C and the small-diameter surface 4D of the permanent magnet 4 form the central hole 4B.

  The thrust type bearing 50 is composed of a first annular member 50A, a second annular member 50B, and rolling elements 50C made of a plurality of balls or rollers that roll between them. It comprises a first annular member 60A, a second annular member 60B, and a rolling element 60C made up of a plurality of balls or rollers that roll between them. These thrust type bearings 50, 60 are somewhat different in structure from ordinary thrust bearings. The first annular member 50A of the thrust type bearing 50 has a central hole with an inner diameter smaller than that of the second annular member 50B, and the central shaft member 1 is press-fitted into the central hole of the first annular member 50A. In close contact with the short cylindrical surface 50a1 of the central hole. However, since the second annular member 50B has a central hole having an inner diameter larger than the outer diameter of the central shaft member 1, the short cylindrical surface 50b1 of the central hole does not substantially contact the central shaft member 1. Similarly, the first annular member 60A of the thrust type bearing 60 has a central hole having an inner diameter smaller than that of the second annular member 60B, and the central shaft member 1 is the central portion of the first annular member 60A. It is press-fitted into the hole and comes into close contact with the short cylindrical surface 60a1 of the central hole. However, since the second annular member 60B has a central hole having an inner diameter larger than the outer diameter of the central shaft member 1, the short cylindrical surface 60b1 forming the central hole does not substantially contact the central shaft member 1.

  Accordingly, the thrust type bearing 50 is fixed to the central shaft member 1 by press-fitting the first annular member 50A and the central shaft member 1, and similarly, the thrust type bearing 60 is the first annular member 60A. And the central shaft member 1 are fixed to the central shaft member 1 by press-fitting. On the other hand, since the second annular member 50B of the thrust type bearing 50 and the second annular member 60B of the thrust type bearing 60 are not in contact with the central shaft member 1, the second annular member 50B is free from the central shaft member 1. It can be rotated. The flat annular outer surface 50a2 of the first annular member 50A of the thrust type bearing 50 is in close contact with the annular flat surface 2C of the hysteresis member 2. Similarly, the flat annular outer surface 60a2 of the first annular member 60A of the thrust type bearing 60 is in close contact with the annular plane 2D of the hysteresis member 2. Further, the flat annular outer surface 50b2 of the second annular member 50B of the thrust type bearing 50 is in close contact with the deep side surface 3E of the permanent magnet 3. Similarly, the flat annular outer surface 60b2 of the second annular member 60B of the thrust type bearing 60 is in close contact with the recessed side surface 4E of the permanent magnet 4.

  As described above, since the thrust bearing generally has a structure that is strong against axial pressure, the thrust bearings 50 and 60 are placed in opposite directions to the annular flat surfaces 2C and 2D of the hysteresis member 2 as shown in FIG. Can be pressed strongly from. Therefore, the depth from the inner side surface 3A of the permanent magnet 3 to the back side surface 3E, the depth from the inner side surface 4A of the permanent magnet 4 to the back side surface 4E, and the thickness dimensions of the thrust type bearings 50 and 60 are appropriately set. By setting, even if the spacer member is not provided as in the first embodiment, the thrust type bearings 50 and 60 can be pressed against the annular flat surfaces 2C and 2D of the hysteresis member 2 with strong force from opposite directions at the time of assembly. The gap between the annular plane 2C of the hysteresis member 2 and the inner side surface 3A of the permanent magnet 3 and the gap between the annular plane 2D of the hysteresis member 2 and the inner side surface 4A of the permanent magnet 4 can be obtained by pressing firmly. It can be a very small distance.

  As an example of changing a part of the second embodiment, the gap between the annular plane 2C of the hysteresis member 2 and the inner side surface 3A of the permanent magnet 3 and between the annular plane 2D of the hysteresis member 2 and the inner side surface 4A of the permanent magnet 4 are described. When it is necessary to adjust the gap, although not shown, the outer diameter is larger than the outer diameter of the central shaft member 1 and smaller than the outer diameter of the first annular members 50A and 60A of the thrust type bearings 50 and 60. Of the first annular member 50A of the thrust type bearing 50, the annular outer surface 60a2 of the first annular member 60A of the thrust type bearing 60, and the hysteresis member 2. A spacer member capable of adjusting the gap as described above may be provided between the annular planes 2C and 2D.

  The operation of the second torque limiter 200 is almost the same as the operation of the first torque limiter 100. In a normal load state, the central shaft member 1 and the hysteresis member 2 rotate together, and the permanent magnets 3, 4 and The permanent magnets 3 and 4 also rotate together with the central shaft member 1 and the hysteresis member 2 by the action of the magnetic force with the hysteresis member 2. However, when an external force larger than a predetermined value is applied to the load side and an overload state occurs, the permanent magnets 3 and 4 side to which a load (not shown) is coupled, that is, the permanent magnets 3 and 4, the connecting member 11, the metal plate 12, 13 cannot rotate, and only the central shaft member 1 and the hysteresis member 2 rotate. At this time, since the second annular members 50B and 60B of the thrust type bearings 50 and 60 are fixed to the permanent magnets 3 and 4 side, they do not rotate, and the rolling elements 50C and 60C rotate, so that the thrust The first annular members 50A, 60A of the mold bearings 50, 60 rotate together with the central shaft member 1 and the hysteresis member 2. Therefore, an overload is not applied to the drive device (not shown) coupled to the central shaft member 1.

  In the second embodiment, a single housing similar to that of the first torque limiter modification 100 ′ shown in FIG. 5 may be used. It is not always necessary to provide the same number of permanent magnets with a hysteresis member interposed therebetween, and one or more permanent magnets may be provided on one side. The outer diameter of the hysteresis member and the permanent magnet may be different, and it is more effective that the outer diameter of the hysteresis member is equal or larger. Further, in order to further improve the heat dissipation of the central shaft member 1, a small hole is provided in the central shaft member 1 along the central axis X or a small groove is provided on the outer peripheral surface of the central shaft member 1 so that air flows. Good. By suppressing the temperature rise of the central shaft member 1, the thermal adverse effect on the permanent magnet can be reduced.

It is a perspective view which shows each member before the assembly of the torque limiter 100 of Embodiment 1 which concerns on invention. It is a figure which shows the cross section of the torque limiter 100 of Embodiment 1. FIG. It is a figure which expands and shows a part of sectional drawing of FIG. It is a figure which shows a part of component of the torque limiter shown in FIG. It is a figure which shows the cross section of torque limiter 100 'which is a modification of the torque limiter which concerns on Embodiment 1. FIG. It is a figure which shows the cross section of the torque limiter 200 which concerns on Embodiment 2 of this invention. It is a figure which expands and shows a part of sectional drawing of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Center shaft member 1A ... Center hole of center shaft member 1 1B ... Attachment part of center shaft member 1 2 ... Hysteresis member 2A ... Center hole of hysteresis member 2 2B ... Center Inner peripheral portions 2C, 2D of the hole 2A: An annular plane of the hysteresis member 3 3. A cylindrical permanent magnet 3A: An annular inner side surface of the permanent magnet 3 3B: A center of the permanent magnet 3 Hole 3C: Large-diameter surface of permanent magnet 3 3D: Small-diameter surface of permanent magnet 3 3E: Recessed side surface of permanent magnet 3 4 ... Cylindrical permanent magnet 4A ... Permanent magnet 4 Annular inner side surface 4B: Center hole of permanent magnet 4 4C: Large diameter surface of permanent magnet 4 4D: Small diameter surface of permanent magnet 4 4E: Recessed side surface of permanent magnet 4, 5, 6 ... Radial bearings 5A, 6A ... Inner rings 5B, 6B ... Outer rings 5C, 6 C ... rolling element 5a, 6a ... inner side surface 7, 8 ... spacer member 9, 10 ... outer peripheral member SA ... engaging portion of outer peripheral member 9, 10 UB ... outer peripheral member 9 10 locking portions 11... Connecting members 11A and 11B... Locking portions 12 and 13... Metal plates 12A and 13A central holes 12B and 13B in the metal plates 12 and 13. ··· Locking portions of metal plates 12 and 13 ··· Connection member 20 · · · Housing member 20A · · · Large diameter portion of housing member 50 · · · Thrust-type bearings 50A and 50B · · · DESCRIPTION OF SYMBOLS 1, 2nd annular member 50C ... Rolling element 50a1 ... Short cylindrical surface of the center hole of the first annular member 50A 50a2 ... Annular outer surface 50b1 of the first annular member 50A The short cylindrical surface 50b2 of the center hole of the second annular member 50B -Annular outer surface of second annular member 50B 60 ... thrust type bearings 60A, 60B ... first and second annular members 60C ... rolling element 60a1 ... first annular shape Short cylindrical surface 60a2 of the central hole of the member 60A ... Annular outer surface 60b1 of the first annular member 60A ... Short cylindrical surface 60b2 of the central hole of the second annular member 60B ... Second circle Annular outer surface of annular member 60B

Claims (8)

A cylindrical central shaft member, a cylindrical hysteresis member engaged with the central shaft member, and a central hole having a diameter larger than the outer diameter of the central shaft member are concentric with the central shaft member. In a torque limiter having a cylindrical permanent magnet arranged,
The hysteresis member has a central hole and front and back annular planes extending in a direction perpendicular to the central shaft member, is engaged with the central shaft member and rotates together with the central shaft member,
The torque limiter, wherein the cylindrical permanent magnet is disposed at a predetermined distance from one or both surfaces of the annular plane of the hysteresis member. In claim 1,
The torque limiter, wherein the central shaft member is made of a synthetic resin material having good heat conduction. In claim 1 or claim 2,
The center shaft member has a small hole or a small groove for heat dissipation extending in the axial direction. In any one of Claims 1 thru | or 3,
A radial bearing having an outer ring engaged with the central hole of the permanent magnet and an inner ring engaged with an outer peripheral surface of the central shaft member;
A spacer member for adjusting the predetermined distance between a side surface of the permanent magnet and the annular plane of the hysteresis member is provided between the hysteresis member and the radial type bearing.
The torque limiter, wherein the spacer member has an outer diameter equal to or smaller than an inner diameter of the outer ring of the radial bearing. In any one of Claims 1 thru | or 3,
A thrust-type bearing having a first annular member and a second annular member that rotate in parallel with each other around the central shaft member on one or both surfaces of the hysteresis member, the hysteresis member and the hysteresis member It has a thrust type bearing arranged between the permanent magnets,
The first annular member is engaged with the central shaft member;
The torque limiter, wherein the second annular member is attracted to the permanent magnet and is not in contact with the central shaft member. In claim 5,
A spacer member for adjusting the predetermined distance between the hysteresis member side of the permanent magnet and the annular plane of the hysteresis member is provided between the hysteresis member and the thrust type bearing, and the spacer member is A torque limiter having an outer diameter equal to or smaller than an outer diameter of the first annular member of the thrust type bearing. In any one of Claims 1 thru | or 6,
A torque limiter characterized in that an annular metal plate is in contact with a side surface of the permanent magnet opposite to the hysteresis member side, and the annular metal plate acts as a back yoke and a side plate. In any one of Claims 1 thru | or 7,
The outer peripheral surface of the cylindrical permanent magnet is covered with a synthetic resin,
A plurality of the permanent magnets are arranged on both sides of the annular plane of the hysteresis member, and these permanent magnets are connected by a connecting member or a housing through the synthetic resin,
The torque limiter, wherein an outer peripheral surface of the hysteresis member does not contact the connecting member or the housing.

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