Torque limiter and power transmission device

Abstract

We provide a torque limiter that enables cost reduction. [Solution] The torque limiter comprises a first side plate, a friction plate, a pressure plate, and a biasing member. The first side plate has an annular portion and a cylindrical portion. The annular portion extends in the circumferential direction. The cylindrical portion extends axially from the outer peripheral end of the annular portion. The friction plate is arranged to be rotatable relative to the first side plate. The pressure plate cooperates with the first side plate to clamp the friction plate. The biasing member biases the pressure plate axially toward the first side plate.

Description

Technical Field

[0001] The present invention relates to a torque limiter and a power transmission device.

Background Art

[0002] The power transmission device disclosed in Patent Document 1 has a flywheel, a torque limiter, and a damper unit. The flywheel has an inertia ring. The torque limiter is attached to the inertia ring.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a torque limiter capable of reducing costs.

Means for Solving the Problems

[0005] The torque limiter according to the first aspect includes a first side plate, a friction plate, a pressure plate, and a biasing member. The first side plate has an annular portion and a cylindrical portion. The annular portion extends in the circumferential direction. The cylindrical portion extends axially from the outer peripheral end of the annular portion. The friction plate is arranged to be relatively rotatable with respect to the first side plate. The pressure plate cooperates with the first side plate to sandwich the friction plate. The biasing member biases the pressure plate axially toward the first side plate.

[0006] In this configuration, since the first side plate has a cylindrical portion extending in the axial direction, this cylindrical portion can function as at least part of the inertial ring. Therefore, at least part of the inertial ring can be omitted. Inertial rings are generally formed by casting, and first side plates are generally formed by sheet metal processing or press working of a metal plate. Here, the first side plate formed by sheet metal processing or press working is cheaper than the inertial ring formed by casting. Therefore, the torque limiter can be made less expensive.

[0007] The torque limiter according to the second embodiment further comprises an inertia member in addition to the torque limiter according to the first embodiment. The inertia member is arranged so as to overlap with the cylindrical portion in a radial view and overlap with the annular portion in an axial view.

[0008] The torque limiter according to the third embodiment is configured as follows in the torque limiter according to the second embodiment: The inertia member has a screw hole extending in the axial direction.

[0009] The torque limiter according to the fourth embodiment is configured as follows in the torque limiter according to the second or third embodiment: The inertia member is annular in shape extending in the circumferential direction. The thickness of the inertia member is greater than the thickness of the first side plate.

[0010] The torque limiter according to the fifth embodiment is configured as follows in the torque limiter according to any of the second to fourth embodiments: The inertia member is a nut that is thicker than the thickness of the first side plate.

[0011] The torque limiter according to the sixth embodiment is configured as follows in the torque limiter according to any of the second to fifth embodiments: The annular portion has a bulge that bulges in the same direction as the cylindrical portion extends. The inertia member is arranged radially between the cylindrical portion and the bulge.

[0012] The torque limiter according to the seventh embodiment further comprises a second side plate in addition to the torque limiter according to any of the first to sixth embodiments. The friction plate, pressure plate, and biasing member are arranged in the axial direction between the first side plate and the second side plate.

[0013] The power transmission device according to the eighth embodiment comprises a torque limiter according to any of the first to seventh embodiments and a damper unit. The damper unit has a first rotating member, a second rotating member, and an elastic member. The first rotating member is configured to rotate integrally with a friction plate. The second rotating member is arranged to be rotatable relative to the first rotating member. The elastic member elastically connects the first rotating member and the second rotating member.

[0014] The power transmission device according to the ninth embodiment is configured as follows in the power transmission device according to the eighth embodiment: The first rotating member has an outer surface that contacts the inner surface of the cylindrical portion.

[0015] The power transmission device according to the 10th embodiment is configured as follows in the power transmission device according to the 9th embodiment: The outer circumferential surface of the first rotating member has a contact portion and a non-contact portion. The contact portion extends in an arc shape when viewed in the axial direction. The contact portion contacts the inner circumferential surface of the cylindrical portion. The non-contact portion extends in a straight line when viewed in the axial direction. The non-contact portion does not contact the inner circumferential surface of the cylindrical portion.

[0016] The power transmission device according to the 11th embodiment further comprises a drive plate in the power transmission device according to any of the 8th to 10th embodiments. The drive plate is configured to receive torque from the prime mover. The first side plate is configured to rotate integrally with the drive plate.

[0017] In the power transmission device according to the 12th embodiment, the cylindrical portion extends axially from the outer peripheral end of the annular portion so as to be separated from the drive plate, in the power transmission device according to the 11th embodiment.

[0018] The power transmission device according to the 13th aspect is the power transmission device according to the 11th aspect, wherein the cylindrical portion extends axially from the outer peripheral end of the annular portion toward the drive plate.

Advantages of the Invention

[0019] According to the present invention, the torque limiter can be made less expensive.

Brief Description of the Drawings

[0020] [Figure 1] Front view of the power transmission device. [Figure 2] Cross-sectional view taken along line II-II of FIG. 1. [Figure 3] Enlarged cross-sectional view of the power transmission device. [Figure 4] Front view of the power transmission device according to the modification. [Figure 5] Cross-sectional view taken along line V-V of FIG. 4. [Figure 6] Cross-sectional view of the power transmission device according to the modification. [Figure 7] Cross-sectional view of the power transmission device according to the modification.

Embodiments for Carrying Out the Invention

[0021] Hereinafter, the torque limiter 3 and the power transmission device 100 according to the present embodiment will be described with reference to the drawings. In the following description, the axial direction is the direction in which the rotation axis O of the torque limiter 3 and the power transmission device 100 extends. The circumferential direction is the circumferential direction of a circle centered on the rotation axis O, and the radial direction is the radial direction of a circle centered on the rotation axis O. The first axial side means the right side in FIG. 2, and the second axial side means the left side in FIG. 2.

[0022] Figure 1 is a front view of the power transmission device 100, and Figure 2 is a cross-sectional view taken along line II-II of Figure 1. As shown in Figures 1 and 2, the power transmission device 100 includes a drive plate 110, a torque limiter 3, and a damper unit 4. The drive plate 110 and the torque limiter 3 are configured to rotate integrally with each other. The torque limiter 3 and the damper unit 4 are rotatable relative to each other, but basically rotate integrally with each other. When the torque transmitted to the power transmission device 100 exceeds a predetermined value, the torque limiter 3 and the damper unit 4 rotate relative to each other.

[0023] The power transmission device 100 is installed between the prime mover (not shown) and the output side member (not shown). The prime mover is, for example, an internal combustion engine. The output side member is, for example, an electric motor or a transmission. The internal combustion engine is positioned on the second axial side (left side in Figure 2) relative to the power transmission device 100, and the output side member is positioned on the first axial side (right side in Figure 2) relative to the power transmission device 100. The power transmission device 100 is configured to limit the torque transmitted between the internal combustion engine and the output side member and to attenuate torque fluctuations.

[0024] [Drive Plate] The drive plate 110 is configured to receive torque from the prime mover. Specifically, the drive plate 110 is attached to the crankshaft (not shown) by, for example, a plurality of bolts 111. The drive plate 110 has a plurality of through holes 110a. Each through hole 110a is spaced apart in the circumferential direction. The drive plate 110 is disc-shaped.

[0025] [Damper Unit] The damper unit 4 is attached to the torque limiter 3. The damper unit 4 is configured to dampen rotational fluctuations. The damper unit 4 has a first rotating member 41, a second rotating member 42, and a plurality of elastic members 43.

[0026] <First rotating member> The first rotating member 41 rotates integrally with the friction plate 33 of the torque limiter 3, which will be described later. The first rotating member 41 has a first plate 41a and a second plate 41b. Both the first plate 41a and the second plate 41b are annular members having a central hole. The first plate 41a and the second plate 41b rotate integrally with each other. Furthermore, the first plate 41a and the second plate 41b are immovable relative to each other in the axial direction.

[0027] The first plate 41a and the second plate 41b are arranged with a gap between them in the axial direction. The second plate 41b is positioned on the second side in the axial direction relative to the first plate 41a.

[0028] The first plate 41a and the second plate 41b each have multiple window portions 411a and 411b. In this embodiment, the first plate 41a and the second plate 41b each have four window portions 411a and 411b, but the number is not limited to this.

[0029] Each window section 411a, 411b is spaced apart from each other in the circumferential direction. Each window section 411a, 411b is configured to accommodate an elastic member 43.

[0030] The outer circumferential surface 412 of the first rotating member 41 is in contact with the inner circumferential surface of the cylindrical portion 312, which will be described later. The outer circumferential surface 412 of the first rotating member 41 is composed of at least one of the outer circumferential surfaces of the first and second plates 41a and 41b. The outer circumferential surface 412 of the first rotating member 41 has a plurality of contact portions 412a and a plurality of non-contact portions 412b. In this embodiment, the outer circumferential surface 412 of the first rotating member 41 has four contact portions 412a and four non-contact portions 412b.

[0031] The contact portion 412a extends in an arc shape when viewed in the axial direction. The contact portion 412a is in contact with the inner circumferential surface of the cylindrical portion 312. The non-contact portion 412b extends in a straight line when viewed in the axial direction. The non-contact portion 412b is not in contact with the inner circumferential surface of the cylindrical portion 312.

[0032] The outer periphery of the first rotating member 41 is positioned radially outward relative to the outer periphery of the friction plate 33. In an axial view, the outer periphery of the first rotating member 41 overlaps with the fastening member 37, which will be described later. Also, in an axial view, the outer periphery of the first rotating member 41 overlaps with the inertia member 36, which will be described later. The outer periphery of the first rotating member 41 is positioned on the first axial side relative to the torque limiter 3.

[0033] <Second rotating member> The second rotating member 42 is configured to transmit torque from the first rotating member 41 to the output member. The second rotating member 42 is positioned axially between the first plate 41a and the second plate 41b. The second rotating member 42 is positioned to be rotatable relative to the first plate 41a and the second plate 41b.

[0034] The second rotating member 42 has a hub 421 and a flange plate 422. The hub 421 and the flange plate 422 are configured as separate members, but they may also be formed integrally as a single member.

[0035] The hub 421 is cylindrical and extends axially. The hub 421 is positioned within the central holes of the first plate 41a and the second plate 41b. Spline holes extending axially are formed on the inner circumference of the hub 421. The input shaft of the output-side member can be spline-fitted into these spline holes.

[0036] The flange plate 422 extends radially from the outer circumferential surface of the hub 421. The flange plate 422 is formed in an annular shape. The flange plate 422 is rotatably positioned relative to the first plate 41a and the second plate 41b. In the axial direction, the flange plate 422 is positioned between the first plate 41a and the second plate 41b.

[0037] The flange plate 422 has a plurality of accommodating holes 423. In this embodiment, the flange plate 422 has four accommodating holes 423, but this number is not limited to this. Each accommodating hole 423 is spaced apart from each other in the circumferential direction. Each accommodating hole 423 is configured to accommodate an elastic member 43. Each accommodating hole 423 is positioned to overlap with each window portion 411a, 411b in an axial view.

[0038] <Elastic material> The elastic member 43 is configured to elastically connect the first rotating member 41 and the second rotating member 42 in the rotational direction. The elastic member 43 is, for example, a coil spring.

[0039] The elastic member 43 is housed in the housing hole 423 of the second rotating member 42. The elastic member 43 is also housed in the window portion 411a of the first plate 41a and in the window portion 411b of the second plate 41b.

[0040] [torque limiter] The torque limiter 3 is rotatably positioned around the rotation axis O. The torque limiter 3 is positioned on the first axial side relative to the drive plate 110. The torque limiter 3 is annular in shape. The torque limiter 3 is configured to be mounted on the drive plate 110.

[0041] The torque limiter 3 is configured to limit the torque transmitted between the drive plate 110 and the damper unit 4. In other words, the torque limiter 3 is configured to restrict the transmission of torque exceeding a predetermined value in the power transmission device 100.

[0042] The torque limiter 3 includes a first side plate 31, a second side plate 32, a friction plate 33, a pressure plate 34, a biasing member 35, and an inertia member 36.

[0043] <First side plate> The first side plate 31 is positioned on the first axial side relative to the drive plate 110. The first side plate 31 is attached to the drive plate 110. Specifically, the first side plate 31 has a plurality of through holes 310. Each through hole 310 is spaced apart in the circumferential direction. Each through hole 310 opens on the second axial side. Each through hole 310 is positioned to communicate with the corresponding through hole 110a of the drive plate 110.

[0044] Multiple bolts 112 fasten the drive plate 110, the first side plate 31, and the inertia member 36. The bolts 112 pass through the through holes 110a in the drive plate 110 and the through holes 310 in the first side plate 31. The first side plate 31 rotates integrally with the drive plate 110. The first side plate 31 is annular in shape. The first side plate 31 is thicker than the drive plate 110.

[0045] Figure 3 is an enlarged cross-sectional view of the power transmission device 100. As shown in Figure 3, the first side plate 31 has an annular portion 311 and a cylindrical portion 312. The annular portion 311 and the cylindrical portion 312 are integrally formed from a single component.

[0046] The annular portion 311 is an annular shape extending in the circumferential direction. The annular portion 311 has a first bulge 311a, a first inner circumferential portion 311b, and a first outer circumferential portion 311c. The first bulge 311a bulges in the axial direction. The first bulge 311a bulges in the same direction as the cylindrical portion 312 extends. That is, the first bulge 311a bulges out to the first axial side. The first bulge 311a bulges out to the first axial side compared to the other parts of the annular portion 311. The first bulge 311a extends in the circumferential direction.

[0047] The first inner circumference portion 311b is positioned radially inward relative to the first bulge portion 311a. The first inner circumference portion 311b is in contact with the friction plate 33.

[0048] The first outer peripheral portion 311c is positioned radially outward relative to the first bulge portion 311a. The first outer peripheral portion 311c is in contact with the inertia member 36. The first outer peripheral portion 311c is also in contact with the drive plate 110. In other words, the first outer peripheral portion 311c is sandwiched between the drive plate 110 and the inertia member 36.

[0049] The cylindrical portion 312 extends axially from the outer peripheral end of the annular portion 311. More specifically, the cylindrical portion 312 extends axially from the outer peripheral end of the annular portion 311 toward the first side. That is, the cylindrical portion 312 extends axially from the outer peripheral end of the annular portion 311 toward the drive plate 110. The cylindrical portion 312 can be formed by bending the outer peripheral portion of the first side plate 31 in the axial direction. The first side plate 31 can be formed by sheet metal processing or press working.

[0050] <Second side plate> The second side plate 32 is positioned on the first axial side relative to the first side plate 31. A friction plate 33, a pressure plate 34, and a biasing member 35 are positioned axially between the first side plate 31 and the second side plate 32. The thickness of the second side plate 32 is thinner than the thickness of the first side plate 31.

[0051] The second side plate 32 is configured to rotate integrally with the first side plate 31. The second side plate 32 is fastened to the first side plate 31 by a plurality of fastening members 37. Each fastening member 37 is spaced apart in the circumferential direction. The fastening members 37 are, for example, rivets.

[0052] The second side plate 32 has a second bulge 321, a second inner circumference 322, and a second outer circumference 323. The second bulge 321 bulges in the axial direction. The second bulge 321 bulges in the opposite direction to the first bulge 311a. That is, the second bulge 321 bulges to the second side in the axial direction. That is, the second bulge 321 bulges toward the first bulge 311a.

[0053] The second bulge 321 extends in the circumferential direction. The second bulge 321 abuts the first bulge 311a in the axial direction. The fastening member 37 fastens the first bulge 311a and the second bulge 321 together.

[0054] The second inner circumference 322 is positioned radially inward relative to the second bulge 321. The second inner circumference 322 supports the biasing member 35. The second inner circumference 322 is positioned at a distance from the first inner circumference 311b in the axial direction. The friction plate 33, the pressure plate 34, and the biasing member 35 are positioned between the first inner circumference 311b and the second inner circumference 322 in the axial direction.

[0055] The second outer periphery 323 is positioned radially outward relative to the second bulge 321. The second outer periphery 323 is positioned at a distance from the first outer periphery 311c in the axial direction. An inertia member 36 is positioned between the first outer periphery 311c and the second outer periphery 323 in the axial direction. The second outer periphery 323 is in contact with the inertia member 36.

[0056] The outer circumferential surface 324 of the second side plate 32 is in contact with the inner circumferential surface of the cylindrical portion 312. As shown in Figure 1, the outer circumferential surface 324 of the second side plate 32 has a plurality of contact portions 324a and a plurality of non-contact portions 324b. In this embodiment, the outer circumferential surface 324 of the second side plate 32 has four contact portions 324a and four non-contact portions 324b.

[0057] The contact portion 324a extends in an arc shape when viewed in the axial direction. The contact portion 324a is in contact with the inner circumferential surface of the cylindrical portion 312. The non-contact portion 324b extends in a straight line when viewed in the axial direction. The non-contact portion 324b is not in contact with the inner circumferential surface of the cylindrical portion 312.

[0058] <Friction Plate> As shown in Figures 2 and 3, the friction plate 33 is an annular plate extending in the circumferential direction. The friction plate 33 is rotatably positioned around the axis of rotation O. The friction plate 33 is rotatably positioned relative to the first side plate 31.

[0059] The friction plate 33 is in contact with the first side plate 31 in the axial direction. More specifically, the friction plate 33 is in contact with the first inner circumference 311b of the annular portion 311 in the axial direction. The friction plate 33 is configured to frictionally engage with the first side plate 31.

[0060] The friction plate 33 is attached to the first rotating member 41. More specifically, the friction plate 33 is attached to the second plate 41b. For example, the friction plate 33 is attached to the second plate 41b by a fastening member 113. The friction plate 33 rotates integrally with the first rotating member 41. Although the friction plate 33 is a separate component from the second plate 41b, the friction plate 33 may be integrally constructed with the second plate 41b as a single component.

[0061] The friction plate 33 comprises a plate body 331, a first friction material 332, and a second friction material 333. The plate body 331 is annular in shape and extends in the circumferential direction. The first friction material 332 is attached to the axial first side surface of the plate body 331. The second friction material 333 is attached to the axial second side surface of the plate body 331. The first and second friction materials 332 and 333 rotate integrally with the plate body 331. The first and second friction materials 332 and 333 are annular in shape. The first and second friction materials 332 and 333 are attached to the outer circumference of the plate body 331.

[0062] <Pressure Plate> The pressure plate 34 is annular in shape. The pressure plate 34 is positioned axially between the biasing member 35 and the friction plate 33. The pressure plate 34 cooperates with the first side plate 31 to clamp the friction plate 33. The first side plate 31 and the pressure plate 34 are in contact with the first and second friction materials 332 and 333.

[0063] The pressure plate 34 is configured to rotate integrally with the first side plate 31. The pressure plate 34 is also movable axially relative to the first side plate 31. Specifically, the pressure plate 34 has a plurality of protrusions 341 that project radially outward (see Figure 2). When these protrusions 341 engage with engagement holes 313 formed in the first side plate 31, the pressure plate 34 rotates integrally with the first side plate 31 while remaining movable axially relative to the first side plate 31.

[0064] <Biasing member> The biasing member 35 is positioned axially between the second side plate 32 and the pressure plate 34. The biasing member 35 biases the pressure plate 34 toward the second axial direction. That is, the biasing member 35 biases the pressure plate 34 toward the first side plate 31. As a result, the friction plate 33 is sandwiched between the pressure plate 34 and the first side plate 31. The biasing member 35 is an annular shape extending in the circumferential direction. The biasing member 35 is, for example, a disc spring. The biasing member 35 is in contact with the second inner circumference portion 322 at its outer peripheral end and in contact with the pressure plate 34 at its inner peripheral end.

[0065] <Inertia component> The inertia member 36 is annular in shape and extends in the circumferential direction. The thickness of the inertia member 36 is greater than the thickness of the first side plate 31. Note that the thickness of the inertia member 36 refers to the axial dimension. The inertia member 36 is positioned on the first axial side relative to the first side plate 31. The inertia member 36 has a plurality of screw holes 361. The screw holes 361 open on the second axial side. Note that in this embodiment, since the screw holes 361 penetrate the inertia member 36 axially, they also open on the first axial side. Each screw hole 361 communicates with the corresponding through hole 310. The bolt 112 is screwed into the screw hole 361 of the inertia member 36. In this way, the torque limiter 3 is attached to the drive plate 110.

[0066] The inertia member 36 is configured to rotate integrally with the first side plate 31. Specifically, the inertia member 36 is attached to the first side plate 31 by a plurality of pins 38. The inertia member 36 is also attached to the first side plate 31 by a plurality of bolts 112.

[0067] In a radial view, the inertia member 36 overlaps with the cylindrical portion 312. More specifically, the outer circumferential surface of the inertia member 36 faces the inner circumferential surface of the cylindrical portion 312. In an axial view, the inertia member 36 overlaps with the annular portion 311. More specifically, in an axial view, the inertia member 36 overlaps with the first outer circumferential portion 311c. The inertia member 36 faces the annular portion 311. Another member may be interposed between the inertia member 36 and the annular portion 311.

[0068] In an axial view, the inertia member 36 overlaps with the second side plate 32. More specifically, in an axial view, the inertia member 36 overlaps with the second outer periphery 323. The inertia member 36 faces the second outer periphery 323. Another member may be interposed between the inertia member 36 and the second outer periphery 323.

[0069] The inertia member 36 is sandwiched in the axial direction between the annular portion 311 of the first side plate 31 and the second side plate 32. More specifically, the inertia member 36 is sandwiched in the axial direction between the first outer peripheral portion 311c and the second outer peripheral portion 323.

[0070] The inertia member 36 is positioned radially outward from the first bulge 311a. The inertia member 36 is positioned radially outward from the second bulge 321. In the radial direction, the inertia member 36 is positioned between the cylindrical portion 312 and the first bulge 311a. Furthermore, in the radial direction, the inertia member 36 is positioned between the cylindrical portion 312 and the second bulge 321. Thus, the inertia member 36 is positioned within the space defined by the cylindrical portion 312, the first outer circumference 311c, the first bulge 311a, the second outer circumference 323, and the second bulge 321.

[0071] [Differentiation] Although embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications are possible without departing from the spirit of the invention. Furthermore, the following modifications can basically be applied simultaneously.

[0072] (a) The inertia member 36 does not have to be annular. For example, as shown in Figures 4 and 5, the inertia member 36 may be composed of a plurality of nuts. Each nut 36 is spaced apart in the circumferential direction. The thickness of each nut 36 is greater than the thickness of the first side plate 31. Figure 4 is a front view of the power transmission device in this modified example, and Figure 5 is a cross-sectional view of Figure 4 along line VV.

[0073] (b) As shown in Figure 6, the cylindrical portion 312 may extend from the outer peripheral end of the annular portion 311 to a second axial direction. That is, the cylindrical portion 312 may extend axially from the outer peripheral end of the annular portion 311 toward the drive plate 110. In this case, the first bulge portion 311a bulges toward the second axial direction. That is, the first bulge portion 311a bulges in the same direction as the cylindrical portion 312 extends.

[0074] The inertia member 36 can be positioned on the second axial side relative to the first side plate 31. The inertia member 36 is sandwiched between the drive plate 110 and the first side plate 31. In this case, the inertia member 36 is fixed to the first side plate 31 by bolts 114. Bolts 112 fasten the drive plate 110 and the inertia member 36.

[0075] (c) In the above embodiment, the torque limiter 3 has an inertia member 36, but the torque limiter 3 does not have to have an inertia member 36.

[0076] (d) In the above embodiment, the inertia member 36 is made of a separate component from the drive plate 110, but the configuration of the inertia member 36 is not limited thereto. For example, as shown in Figure 7, the inertia member 36 may be formed integrally with the drive plate 110. Also, the second side plate 32 may be positioned on the second axial side relative to the first side plate 31. [Explanation of symbols]

[0077] 3: Torque limiter 31: First side plate 311: Ring section 311a: 1st bulge 312: Cylindrical section 32: Second side plate 324: Outer surface 324a: Contact part 324b: Non-contact part 33: Friction Plate 34: Pressure Plate 35: Biasing member 36: Inertia component 361: Screw hole 4: Damper Unit 41: First rotating member 42: Second rotating member 43: Elastic member 100: Power transmission device 110: Drive Plate 112: Bolt

Claims

1. A first side plate having an annular portion extending in the circumferential direction and a cylindrical portion extending axially from the outer peripheral end of the annular portion, A friction plate is arranged to be rotatable relative to the first side plate, A pressure plate that cooperates with the first side plate to clamp the friction plate, A biasing member that biases the pressure plate axially toward the first side plate, A torque limiter equipped with this feature.

2. The system further comprises an inertia member that overlaps with the cylindrical portion in a radial view and overlaps with the annular portion in an axial view. The torque limiter according to claim 1.

3. The inertia member has a screw hole extending in the axial direction. The torque limiter according to claim 2.

4. The inertia member is an annular shape extending in the circumferential direction, The thickness of the inertia member is greater than the thickness of the first side plate. The torque limiter according to claim 2.

5. The inertia member is a nut that is thicker than the thickness of the first side plate. The torque limiter according to claim 2.

6. The annular portion has a bulge that expands in the same direction as the cylindrical portion extends, The inertia member is positioned radially between the cylindrical portion and the bulging portion. The torque limiter according to claim 2.

7. Further equipped with a second side plate, The friction plate, the pressure plate, and the biasing member are arranged in the axial direction between the first side plate and the second side plate. The torque limiter according to claim 1.

8. A torque limiter according to any one of claims 1 to 7, A damper unit having a first rotating member configured to rotate integrally with the friction plate, a second rotating member arranged to be rotatable relative to the first rotating member, and an elastic member elastically connecting the first rotating member and the second rotating member, A power transmission device equipped with the following features.

9. The first rotating member has an outer surface that contacts the inner surface of the cylindrical portion. The power transmission device according to claim 8.

10. The outer circumferential surface of the first rotating member is In an axial view, the contact portion extends in an arc shape and abuts against the inner circumferential surface of the cylindrical portion, A non-contact portion that extends linearly in an axial view and does not come into contact with the inner circumferential surface of the cylindrical portion, Having, The power transmission device according to claim 9.

11. It further includes a drive plate configured to receive torque from the prime mover, The first side plate is configured to rotate integrally with the drive plate. The power transmission device according to claim 8.

12. The cylindrical portion extends axially from the outer peripheral end of the annular portion so as to move away from the drive plate. The power transmission device according to claim 11.

13. The cylindrical portion extends axially from the outer peripheral end of the annular portion toward the drive plate, The power transmission device according to claim 11.

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