Torque limiter

Abstract

A torque limiter 10 comprises: a first rotary body 12; a second rotary body 14 fitted onto the outer side of the first rotary body 12; a permanent magnet 16 located inside the second rotary body 14 and supported on the outer peripheral surface of the first rotary body 12; and a hysteresis material 18 supported on the inner peripheral surface of the second rotary body 14 and opposed to the permanent magnet 16. The first rotary body 12 includes: a cylindrical shaft part 22; a support part 24 protruding from the shaft part 22 outward in the radial direction of the first rotary body 12; a cantilevered beam part 26 supported on the support part 24 and extending from the support part 24 toward one side in the axial direction X of the first rotary body 12; and a claw part 28 protruding from the beam part 26 outward in the radial direction. The permanent magnet 16 is fitted onto the support part 24 such that the claw part 28 is located further toward the one side in the axial direction X than the permanent magnet 16.

Description

Torque limiter

[0001] The present invention relates to a torque limiter.

[0002] In various devices such as copiers and ATMs, torque limiters using hysteresis torque are used. For example, the torque limiter disclosed in Patent Document 1 includes a cylindrical outer rotating body, an inner rotating body incorporated in the outer rotating body, a permanent magnet fixed to the outer periphery of the inner rotating body, and a semi-rigid magnetic body fixed to the inner periphery of the outer rotating body so as to face the permanent magnet. In such a torque limiter, rotation transmission and interruption are performed by utilizing the hysteresis torque generated between the permanent magnet and the semi-rigid magnetic body.

[0003] Japanese Patent Application Laid-Open No. 2004-308767

[0004] Patent Document 1 describes, as an example of means for fixing a permanent magnet to an inner rotating body, forming a plurality of protrusions on the outer periphery of the inner rotating body that are in pressure contact with the inner peripheral surface of the permanent magnet. However, as a result of studies by the present inventors, it has been found that when a plurality of protrusions in pressure contact as described above are provided as means for fixing the permanent magnet, there is a risk that the inner peripheral surface of the permanent magnet will be scraped by the protrusions when the permanent magnet is fitted onto the inner rotating body. If the inner peripheral surface of the permanent magnet is scraped, it will cause damage to the permanent magnet and impair the durability of the torque limiter.

[0005] Therefore, an object of the present invention is to provide a torque limiter capable of suppressing a decrease in durability.

[0006] (1) A torque limiter according to one embodiment of the present invention comprises: a cylindrical first rotating body; a cylindrical second rotating body fitted to the outside of the first rotating body so as to be rotatable with respect to the first rotating body coaxially with the first rotating body; a first cylindrical member supported on the outer circumferential surface of the first rotating body inside the second rotating body; and a second cylindrical member supported on the inner circumferential surface of the second rotating body so as to be opposite to the first cylindrical member in the radial direction of the first rotating body, wherein one of the first cylindrical member and the second cylindrical member is a permanent magnet, and the other is a hysteresis material that generates hysteresis torque with respect to the permanent magnet, the first rotating body comprises: a cylindrical shaft portion that rotatably supports the second rotating body; and a support portion provided so as to protrude outward in the radial direction from the shaft portion, and the first cylindrical member fitted to the outside in the radial direction, The first rotating body has a beam portion that extends from the support portion toward one side in the axial direction so as to pass inside the first cylindrical member in the radial direction, and is supported by the support portion in a cantilevered manner such as forming a space on the inside in the radial direction when viewed from the axial direction, and a claw portion that protrudes radially outward from the beam portion so as to be located on the one side in the axial direction of the first cylindrical member.

[0007] (2) The first cylindrical member may be a permanent magnet, and the second cylindrical member may be a hysteresis material.

[0008] (3) The torque limiter may include a restricting part that contacts the first cylindrical member from the other side in the axial direction, thereby restricting the first cylindrical member from moving to the other side in the axial direction relative to the first rotating body.

[0009] (4) The restricting portion is provided so as to protrude outward in the radial direction from the support portion, and the first cylindrical member may be attached to the support portion by being sandwiched between the claw portion and the restricting portion.

[0010] (5) A first recess is formed at one end of the support portion in the axial direction, which is recessed to the other end in the axial direction, and the beam portion may be provided so as to be located within the first recess.

[0011] (6) The other end of the first cylindrical member in the axial direction is formed in a second recess that is recessed to the one side in the axial direction, and the restricting portion may be fitted into the second recess.

[0012] (7) The permanent magnet may be a samarium-iron-nitrogen magnet.

[0013] (8) The first rotating body may be made of polyacetal resin.

[0014] According to the present invention, a torque limiter that can suppress a decrease in durability can be obtained.

[0015] Figure 1 is a cross-sectional view showing a torque limiter according to one embodiment of the present invention. Figure 2 is a perspective view showing a first rotating body. Figure 3 is a perspective view showing the first rotating body and a permanent magnet. Figure 4 is a perspective view showing a modified first rotating body. Figure 5 is a diagram illustrating another example of the first rotating body and permanent magnet. Figure 6 is a diagram illustrating another example of the first rotating body and permanent magnet.

[0016] Hereinafter, a torque limiter according to an embodiment of the present invention will be described with reference to the drawings.

[0017] (Configuration of Torque Limiter) Figure 1 is a cross-sectional view showing a torque limiter according to one embodiment of the present invention. In Figure 1, an arrow X is shown indicating the axial direction of the first rotating body 12, which will be described later. Similarly, in Figures 2 to 6, which will be described later, an arrow X is shown indicating the axial direction of the first rotating body 12. Hereinafter, the axial direction of the first rotating body 12 will be referred to as axial direction X.

[0018] As shown in Figure 1, the torque limiter 10 according to this embodiment comprises a first rotating body 12, a second rotating body 14, a permanent magnet 16, a hysteresis material 18, and a cap 20. The first rotating body 12, the second rotating body 14, the permanent magnet 16, and the hysteresis material 18 are each formed in a cylindrical shape. The cap 20 is formed in a hollow disc shape.

[0019] Figure 2 is a perspective view showing the first rotating body 12, and Figure 3 is a perspective view showing the first rotating body 12 and the permanent magnet 16.

[0020] As shown in Figure 1, the first rotating body 12 and the second rotating body 14 are mounted coaxially. The second rotating body 14 is fitted to the outside of the first rotating body 12 so that it can rotate relative to the first rotating body 12.

[0021] As shown in Figures 1 and 2, the first rotating body 12 has a shaft portion 22, a support portion 24, a plurality (two in this embodiment) of beam portions 26, a plurality (two in this embodiment) of claw portions 28, and a plurality (two in this embodiment) of restricting portions 30.

[0022] The shaft portion 22 is formed in a cylindrical shape (in this embodiment, cylindrical). Referring to Figure 1, the shaft portion 22 rotatably supports the second rotating body 14. In this embodiment, one end 22a of the shaft portion 22 rotatably supports the flange portion 14a, which will be described later, formed on one end of the second rotating body 14. The other end 22b of the shaft portion 22 rotatably supports the other end of the second rotating body 14 via the cap 20.

[0023] As shown in Figures 1 and 2, the support portion 24 is provided so as to protrude outward from the shaft portion 22 in the radial direction of the first rotating body 12. As shown in Figures 1 and 3, the permanent magnet 16 is fitted to the outside of the support portion 24 in the radial direction of the first rotating body 12. The permanent magnet 16 is fitted to the support portion 24 so as to rotate integrally with the support portion 24.

[0024] As shown in Figures 1 and 2, the beam portion 26 is cantilevered to the support portion 24 so as to extend from the support portion 24 toward one side in the axial direction X. As shown in Figure 1, the beam portion 26 is provided so as to pass inside the permanent magnet 16 in the radial direction of the first rotating body 12. Furthermore, the beam portion 26 is provided so as to form a space 32 inside the radial direction of the first rotating body 12 when viewed from the axial direction X. In this embodiment, a space 32 is formed between the shaft portion 22 and the beam portion 26 when viewed from the axial direction X. In this embodiment, the multiple beam portions 26 are arranged at equal intervals in the circumferential direction of the first rotating body 12. In this embodiment, two beam portions 26 are arranged 180° apart in the circumferential direction of the first rotating body 12.

[0025] As shown in Figures 1 and 2, in this embodiment, a plurality of recesses (two in this embodiment) 24a are formed at one end of the support portion 24 in the axial direction X, so as to be recessed to the other side in the axial direction X. In this embodiment, a beam portion 26 is provided for each recess 24a. The beam portion 26 is supported by the support portion 24 so as to be located within the recess 24a. In this embodiment, the recess 24a corresponds to the first recess.

[0026] As shown in Figures 1 and 3, the claw portion 28 protrudes radially outward from the beam portion 26 of the first rotating body 12 so as to be located on one side of the permanent magnet 16 in the axial direction X. In this embodiment, the claw portion 28 is provided at one end of the beam portion 26 in the axial direction X.

[0027] As shown in Figures 1 and 2, the multiple restricting portions 30 are provided so as to protrude outward from the support portion 24 in the radial direction of the first rotating body 12. In this embodiment, the multiple restricting portions 30 are provided at the other end of the support portion 24 in the axial direction X. The multiple restricting portions 30 are arranged at equal intervals in the circumferential direction of the first rotating body 12. In this embodiment, two restricting portions 30 are arranged 180° apart in the circumferential direction of the first rotating body 12.

[0028] The first rotating body 12 is constructed, for example, using a synthetic resin. Examples of synthetic resins include polyacetal resin, polybutylene terephthalate resin, polyamide resin, polyolefin resin, polyimide resin, polycarbonate resin, polyether ether ketone resin, polypropylene resin, polyetherimide resin, liquid crystal polymer, polyether nitrile resin, polyether ketone resin, polyphenylene sulfide resin, polyphenylene oxide resin, phenolic resin, epoxy resin, and acrylonitrile-butadiene-styrene resin.

[0029] The second rotating body 14 and the cap 20 can also be constructed using the same materials as the first rotating body 12. The first rotating body 12, the second rotating body 14, or the cap 20 may be constructed using materials other than synthetic resin. For example, the first rotating body 12, the second rotating body 14, or the cap 20 may be constructed using metal. Examples of metals include aluminum, zinc, brass, stainless steel, and iron.

[0030] Inside the second rotating body 14, a permanent magnet 16 is supported on the outer circumferential surface of the first rotating body 12. As shown in Figures 1 and 3, a plurality of recesses 16a (two in this embodiment) are formed at the other end of the permanent magnet 16 in the axial direction X, so as to be recessed to one side in the axial direction X. The plurality of recesses 16a are arranged at equal intervals in the circumferential direction of the permanent magnet 16. Each recess 16a is formed to penetrate the permanent magnet 16 in the radial direction. In this embodiment, a recess 16a is provided for each restricting portion 30, and two recesses 16a are arranged 180° apart in the circumferential direction of the permanent magnet 16. In this embodiment, the recess 16a corresponds to the second recess.

[0031] In this embodiment, the permanent magnet 16 is fitted into the support portion 24 of the permanent magnet 16 from one side in the axial direction X. More specifically, as shown in Figures 1 and 3, the permanent magnet 16 is fitted into the support portion 24 such that the plurality of restricting portions 30 fit into the plurality of recesses 16a, and the plurality of claw portions 28 are positioned on one side in the axial direction X relative to the end face of the permanent magnet 16 in the axial direction X.

[0032] In this embodiment, the movement of the permanent magnet 16 to one side in the axial direction X relative to the support portion 24 is restricted by the claw portion 28, and the movement of the permanent magnet 16 to the other side in the axial direction X relative to the support portion 24 is restricted by the restricting portion 30. Thus, in this embodiment, the permanent magnet 16 is attached to the support portion 24 by being sandwiched between a plurality of claw portions 28 and a plurality of restricting portions 30.

[0033] For example, a rare earth magnet can be used as the permanent magnet 16. More specifically, for example, a samarium-iron-nitrogen magnet or a neodymium-iron-boron magnet can be used as the permanent magnet 16.

[0034] As shown in Figure 1, a hysteresis material 18 is supported on the inner circumferential surface of the second rotating body 14 so as to face the permanent magnet 16 in the radial direction of the first rotating body 12. The hysteresis material 18 is fixed to the inner circumferential surface of the second rotating body 14 by, for example, press-fitting it into the second rotating body 14. In this embodiment, a gap is formed between the permanent magnet 16 and the hysteresis material 18.

[0035] In this embodiment, an annular flange portion 14a is provided at one end of the second rotating body 14 so as to protrude radially inward from the second rotating body 14. As described above, the flange portion 14a is rotatably supported on one end 22a of the shaft portion 22 of the first rotating body 12. A cap 20 is fixed to the inside of the other end of the second rotating body 14. As described above, the cap 20 is rotatably supported on the other end 22b of the shaft portion 22 of the first rotating body 12. In this embodiment, the hysteresis material 18 is supported on the inner circumferential surface of the second rotating body 14 between the flange portion 14a and the cap 20. In this embodiment, the permanent magnet 16 corresponds to the first cylindrical member, and the hysteresis material 18 corresponds to the second cylindrical member.

[0036] In this specification, the state in which the permanent magnet 16 and the hysteresis material 18 are facing each other in the radial direction means that one of the permanent magnet 16 and the hysteresis material 18 is positioned inside the other. Therefore, even if another cylindrical member is inserted between the permanent magnet 16 and the hysteresis material 18, the state in which one of the permanent magnet 16 and the hysteresis material 18 is positioned inside the other is the same as the state in which the permanent magnet 16 and the hysteresis material 18 are facing each other in the radial direction.

[0037] The hysteresis material 18 is constructed using a semi-hard magnetic material. Specifically, for example, the hysteresis material 18 can be constructed by performing a predetermined magnetic field treatment on a semi-hard magnetic material such as an Fe-Cr-Co alloy or Fe-Co alloy. In this embodiment, the magnetic flux density of the hysteresis material 18 is preferably 0.7 T or higher, and the coercivity is preferably 15 to 80 kA / m.

[0038] Although not shown in the diagram, a rotating shaft, which is driven to rotate by a drive device, is inserted into the shaft portion 22 of the first rotating body 12. The rotating shaft is connected to the first rotating body 12 (shaft portion 22) so as to rotate integrally with the first rotating body 12 (shaft portion 22). The rotating shaft is inserted into the first rotating body 12 so as to be rotatable relative to the second rotating body 14.

[0039] A rotating member (not shown) is attached to the second rotating body 14. When the torque limiter 10 according to this embodiment is used in a paper feeding device, the rotating member is, for example, a retard roller (friction roller) that is provided to press against a feed roller (paper feeding roller).

[0040] In the torque limiter 10 according to this embodiment, the first rotating body 12 and the permanent magnet 16 are rotated by the above-mentioned drive device (not shown). As a result, a hysteresis torque is generated between the permanent magnet 16 and the hysteresis material 18, causing the hysteresis material 18 and the second rotating body 14 to rotate. As a result, a predetermined torque is applied to the rotating member.

[0041] (Effects of this embodiment) In the torque limiter 10 according to this embodiment, a beam portion 26 and a claw portion 28 are provided as means for attaching a permanent magnet 16 to the support portion 24 of the first rotating body 12. The beam portion 26 is cantilevered to the support portion 24 such that a space 32 is formed on the inside of the first rotating body 12 in the radial direction and extends from the support portion 24 to one side in the axial direction X. In this configuration, when fitting the permanent magnet 16 to the support portion 24 from one side in the axial direction X, the beam portion 26 can be bent radially inward of the first rotating body 12. As a result, even if the claw portion 28 comes into contact with the inner circumferential surface of the permanent magnet 16 when fitting the permanent magnet 16 to the support portion 24, it is possible to prevent a large force from being applied to the permanent magnet 16 from the claw portion 28. In this case, it is possible to prevent the inner circumferential surface of the permanent magnet 16 from being scraped by the claw portion 28, thereby preventing damage to the permanent magnet 16 and suppressing a decrease in the durability of the torque limiter 10. Furthermore, since the claw portion 28 is not subjected to wear, the generation of wear debris from the claw portion 28 can be suppressed. In addition, the bending of the beam portion 26 reduces the load on the permanent magnet 16 when fitting the permanent magnet 16 into the support portion 24, thus making the assembly of the torque limiter 10 easier. The number of beam portions 26 and claw portions 28 may be one or three or more. The same applies to the embodiments described later.

[0042] In the torque limiter 10 according to this embodiment, the permanent magnet 16 is attached to the support portion 24 by being sandwiched between the claw portion 28 and the restricting portion 30 in the axial direction X. Therefore, in order to attach the permanent magnet 16 to the support portion 24, it is not necessary to provide multiple protrusions on the outer circumferential surface of the support portion 24 that contact the permanent magnet 16 so as to press against the inner circumferential surface of the permanent magnet 16. Thus, the permanent magnet 16 can be attached to the support portion 24 while preventing the inner circumferential surface of the permanent magnet 16 from being worn down. As a means of attaching the permanent magnet to the support portion, it is also conceivable to provide multiple protrusions on the inner circumferential surface of the permanent magnet that contact the support portion 24 so as to press against the outer circumferential surface of the support portion 24. However, in this case, there is a risk of wear debris being generated due to the tips of the protrusions being worn down. In contrast, in the torque limiter 10 according to this embodiment, it is not necessary to provide multiple protrusions on the inner circumferential surface of the permanent magnet 16 in order to attach the permanent magnet 16 to the support portion 24, so the generation of wear debris can be prevented.

[0043] In the torque limiter 10 according to this embodiment, a recess 24a is formed at one end of the support portion 24 in the axial direction X, and a beam portion 26 is provided within the recess 24a. In this case, the claw portion 28 can be brought sufficiently close to one end of the support portion 24 in the axial direction X. As a result, when the permanent magnet 16 is sandwiched between the claw portion 28 and the restricting portion 30, one end of the permanent magnet 16 in the axial direction X can be appropriately supported by one end of the support portion 24 in the axial direction X. Consequently, the permanent magnet 16 can be stably supported by the support portion 24.

[0044] In the torque limiter 10 according to this embodiment, a recess 16a is formed at the other end of the permanent magnet 16 in the axial direction X, and the restricting portion 30 of the first rotating body 12 is fitted into the recess 16a. In this case, by engaging the recess 16a and the restricting portion 30 with each other, it is possible to reliably prevent the permanent magnet 16 from rotating with respect to the first rotating body 12. Thereby, it is possible to prevent a decrease in the performance of the torque limiter 10. That is, in this embodiment, the restricting portion 30 and the recess 16a function as a rotation preventing portion that prevents the permanent magnet 16 from rotating with respect to the first rotating body 12. The number of restricting portions may be one or three or more. The same applies to the embodiments described later.

[0045] (Modification) In the above-described embodiment, the beam portion 26 is provided so as to be supported by the bottom surface of the recess 24a formed in the support portion 24. However, the configurations of the support portion and the beam portion are not limited to the above example. For example, as shown in FIG. 4, the support portion 24 may have a first portion 241 in which a recess 24a is formed at one end in the axial direction X, and a second portion 242 that protrudes radially outward from the shaft portion 22 to the first rotating body 12 within the recess 24a, and the beam portion 26 may be supported by the second portion 242. Also, although not shown, the support portion 24 may be divided into three or more portions.

[0046] In the above-described embodiment, the case where the first rotating body 12 has the restricting portion 30 provided so as to protrude outward from the support portion 24 in the radial direction of the first rotating body 12 has been described. However, the restricting portion only needs to be configured so that the permanent magnet 16 can be sandwiched between the restricting portion and the claw portion 28 in the axial direction X. That is, the restricting portion only needs to be configured so that it can contact the permanent magnet 16 from the other side in the axial direction X. Also, in the above-described embodiment, the case where the restricting portion 30 and the recess 16a function as a rotation preventing portion that prevents the permanent magnet 16 from rotating with respect to the first rotating body 12 has been described. However, the configuration of the rotation preventing portion provided in the torque limiter is not limited to the above example. Hereinafter, other examples of the restricting portion and the rotation preventing portion will be briefly described.

[0047] FIG. 5 is a diagram for explaining another example of the first rotating body 12 and the permanent magnet 16. (a) shows a cross section of the first rotating body 12 and the permanent magnet 16 that is parallel to the axial direction X and passes through a pair of beam portions 26, and (b) shows a cross section of the b-b portion in (a).

[0048] As shown in FIG. 5(a), in the present embodiment, a plurality of restricting portions 30 (see FIG. 1) are not provided at the other end portion of the support portion 24 in the axial direction X. On the other hand, as shown in FIG. 5(b), a plurality of restricting portions 30a are provided at one end portion of the support portion 24 in the axial direction X. Each restricting portion 30a is formed so as to be recessed inward in the radial direction of the first rotating body 12 on the outer peripheral surface of the support portion 24. Further, each restricting portion 30a is formed so as to extend from one end face of the support portion 24 toward the other side in the axial direction X. In the present embodiment, the plurality of restricting portions 30a are arranged at equal intervals in the circumferential direction of the first rotating body 12. In the present embodiment, two restricting portions 30a are arranged 180° apart in the circumferential direction of the first rotating body 12.

[0049] Also, as shown in FIG. 5(a), in the present embodiment, a plurality of recesses 16a (see FIG. 3) are not provided at the other end portion of the permanent magnet 16 in the axial direction X. On the other hand, as shown in FIG. 5(b), a plurality of protruding portions 16b are provided at one end portion of the permanent magnet 16 in the axial direction X. Each protruding portion 16b is formed so as to protrude inward in the radial direction of the permanent magnet 16 on the inner peripheral surface of the permanent magnet 16. Further, each protruding portion 16b is formed so as to extend from one end face of the permanent magnet 16 toward the other side in the axial direction X. In the present embodiment, the plurality of protruding portions 16b are arranged at equal intervals in the circumferential direction of the permanent magnet 16. In the present embodiment, two protruding portions 16b are arranged 180° apart in the circumferential direction of the permanent magnet 16.

[0050] In this embodiment, the permanent magnet 16 is fitted into the support portion 24 from one side in the axial direction X such that the multiple protrusions 16b each fit into the multiple restricting portions 30a, and the multiple claw portions 28 are positioned on one side in the axial direction X relative to one end face of the permanent magnet 16 in the axial direction X. As a result, the permanent magnet 16 is attached to the support portion 24 by being sandwiched between the claw portions 28 and the restricting portions 30a (more specifically, the wall surface of the other end of the restricting portion 30a in the axial direction X) in the axial direction X. Furthermore, the fitting of the protrusions 16b into the restricting portions 30a reliably prevents the permanent magnet 16 from rotating relative to the first rotating body 12. In other words, in this embodiment, the restricting portions 30a and the protrusions 16b function as rotation prevention portions that prevent the permanent magnet 16 from rotating relative to the first rotating body 12. In this embodiment, it is sufficient that the protrusion 16b and the restricting portion 30a can contact each other in the axial direction X and the circumferential direction of the first rotating body 12, and it is not necessary to form the protrusion 16b in such a way that it presses against the outer circumferential surface of the support portion 24. This prevents the protrusion 16b from being worn down when the permanent magnet 16 is fitted into the support portion 24. The shape of the restricting portion 30a and the protrusion 16b in a cross section perpendicular to the axial direction X is not particularly limited, but may be U-shaped, V-shaped, or arc-shaped, for example.

[0051] Figure 6 illustrates other examples of the first rotating body 12 and permanent magnet 16, where (a) shows a cross-section of the first rotating body 12 and permanent magnet 16 parallel to the axial direction X and passing through a pair of beams 26, and (b) shows one end face of the permanent magnet 16 in the axial direction X of (a).

[0052] As shown in Figure 6(a), in this embodiment as well, there are no multiple restricting portions 30 (see Figure 1) at the other end of the support portion 24 in the axial direction X. On the other hand, in this embodiment, an inclined portion 24b is provided on the outer circumferential surface of the support portion 24. The inclined portion 24b is provided on the other side of the recess 24a in the axial direction X. In this embodiment, the inclined portion 24b is tapered so that its diameter gradually decreases from the other side of the support portion 24 in the axial direction X towards the one side in the axial direction X.

[0053] Furthermore, in this embodiment as well, there are no multiple recesses 16a (see Figure 3) at the other end of the permanent magnet 16 in the axial direction X. On the other hand, in this embodiment, an inclined portion 16c is provided on the inner circumferential surface of the permanent magnet 16. The inclined portion 16c is formed such that its diameter gradually decreases from the other side in the axial direction X of the permanent magnet 16 toward the one side in the axial direction X, corresponding to the inclined portion 24b of the support portion 24.

[0054] Furthermore, in this embodiment, a plurality of recesses 16d are provided on one end face of the permanent magnet 16 in the axial direction X, recessing toward the other side in the axial direction X. In this embodiment, the plurality of recesses 16d are arranged at equal intervals in the circumferential direction of the permanent magnet 16. In this embodiment, two recesses 16d are arranged 180° apart in the circumferential direction of the permanent magnet 16.

[0055] In this embodiment, the permanent magnet 16 is fitted into the support portion 24 from one side in the axial direction X such that the multiple claw portions 28 fit into the multiple recesses 16d and the inclined portion 24b contacts the inclined portion 16c. As a result, the permanent magnet 16 is attached to the support portion 24 by being sandwiched between the claw portions 28 and the inclined portion 24b in the axial direction X. In other words, in this embodiment, the inclined portion 24b functions as a restricting portion. Furthermore, the claw portions 28 catch on the recesses 16d, which reliably prevents the permanent magnet 16 from rotating relative to the first rotating body 12. In other words, in this embodiment, the claw portions 28 and the recesses 16d function as rotation prevention portions.

[0056] In the above-described embodiment, a case was explained in which a portion that interlocks with each other in the circumferential direction of the first rotating body 12 and the permanent magnet 16 is formed as the rotation prevention portion. However, the configuration of the rotation prevention portion is not limited to the above example. For example, a member that interlocks with the first rotating body 12 and the permanent magnet 16 in the circumferential direction of the first rotating body 12 may be provided as the rotation prevention portion. In other words, a member separate from the first rotating body 12 and the permanent magnet 16 may be provided as the rotation prevention portion.

[0057] In the above-described embodiment, a plurality of recesses 24a are formed at one end of the support portion 24 in the axial direction X, and the beam portion 26 is provided within the recesses 24a, but the recesses 24a do not necessarily have to be formed.

[0058] In the above-described embodiment, a case was explained in which a permanent magnet 16 is provided on the first rotating body 12 and a hysteresis material 18 is provided on the second rotating body 14. However, the positional relationship between the permanent magnet and the hysteresis material may be reversed. That is, the hysteresis material as a first cylindrical member may be provided on the first rotating body 12, and the permanent magnet as a second cylindrical member may be provided on the second rotating body 14. In this case, the hysteresis material may be formed in the same shape as the permanent magnet 16 described above. When fitting the hysteresis material into the support portion 24, the beam portion 26 flexes, which prevents the inner circumferential surface of the hysteresis material from being scraped, as in the above-described embodiment, and allows the hysteresis material to be easily fitted into the support portion 24.

[0059] In the above-described embodiment, the second rotating body 14 is composed of a single member, but the second rotating body may be composed of multiple members. For example, the second rotating body may be composed of a first member and a second member separated in the axial direction, and a hysteresis material or permanent magnet may be fixed to the first member and the second member so as to connect the first member and the second member.

[0060] In the above-described embodiment, the flange portion 14a and cap 20 of the second rotating body 14 are directly supported by the first rotating body 12, but they may be rotatably supported by the first rotating body via bearings (sliding bearings, rolling bearings, etc.).

[0061] In the torque limiter 10 shown in Figure 1, the permanent magnet 16 is in contact with the claw portion 28 and the restricting portion 30 in the axial direction X. However, a gap may be formed between the permanent magnet 16 and the claw portion 28 or between the permanent magnet 16 and the restricting portion 30 in the axial direction X. In other words, it is permissible for the permanent magnet 16 to be slightly misaligned in the axial direction X relative to the support portion 24, as long as it does not affect the function of the torque limiter 10. Similarly, when attaching the permanent magnet 16 to the first rotating body 12 shown in Figures 4 to 6, it is permissible for the permanent magnet 16 to be slightly misaligned in the axial direction X relative to the support portion 24, as long as it does not affect the function of the torque limiter.

[0062] According to the present invention, a torque limiter that can suppress a decrease in durability can be obtained.

[0063] 10 Torque limiter 12 First rotating body 14 Second rotating body 16 Permanent magnet 18 Hysteresis material 20 Cap 22 Shaft section 24 Support section 26 Beam section 28 Claw section 30 Restricting section 32 Space

Claims

1. A cylindrical first rotating body; a cylindrical second rotating body fitted to the outside of the first rotating body so as to be rotatable with respect to the first rotating body coaxially with the first rotating body; a first cylindrical member supported on the outer circumferential surface of the first rotating body inside the second rotating body; and a second cylindrical member supported on the inner circumferential surface of the second rotating body so as to be opposite to the first cylindrical member in the radial direction of the first rotating body, wherein one of the first cylindrical member and the second cylindrical member is a permanent magnet, and the other is a hysteresis material that generates hysteresis torque with respect to the permanent magnet, the first rotating body comprises a cylindrical shaft portion that rotatably supports the second rotating body; a support portion provided so as to protrude outward in the radial direction from the shaft portion and to which the first cylindrical member is fitted on the outer side in the radial direction; and a beam portion that extends from the support portion toward one side in the axial direction of the first rotating body so as to pass inside the first cylindrical member in the radial direction and is cantilevered to the support portion such that a space is formed on the inner side in the radial direction when viewed from the axial direction, A torque limiter having a claw portion that protrudes radially outward from the beam portion so as to be located on one side of the first cylindrical member in the axial direction.

2. The torque limiter according to claim 1, wherein the first cylindrical member is a permanent magnet and the second cylindrical member is a hysteresis material.

3. The torque limiter according to claim 1, further comprising a restricting portion that restricts the movement of the first cylindrical member to the other side in the axial direction relative to the first rotating body by contacting the first cylindrical member from the other side in the axial direction.

4. The torque limiter according to claim 3, wherein the restricting portion is provided so as to protrude radially outward from the support portion, and the first cylindrical member is attached to the support portion by being sandwiched between the claw portion and the restricting portion.

5. The torque limiter according to claim 1, wherein a first recess is formed at one end of the support portion in the axial direction, and the beam portion is provided to be located within the first recess.

6. The torque limiter according to claim 4, wherein a second recess is formed at the other end of the first cylindrical member in the axial direction, recessing toward the one end in the axial direction, and the restricting portion is fitted into the second recess.

7. The torque limiter according to claim 1, wherein the permanent magnet is a samarium-iron-nitrogen magnet.

8. The torque limiter according to claim 1, wherein the first rotating body is made of polyacetal resin.

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