阅读说明：本技术 力矩限制装置 (Moment limiting device ) 是由 冨田雄亮 冈町悠介 于 2020-03-04 设计创作，主要内容包括：本发明公开了在盖的内部收纳构成零件的力矩限制装置,从而实现径向和轴向的小型化。该力矩限制装置(2)具备盖(10)、摩擦盘(12)以及锥形弹簧(14)。盖(10)具有连接至飞轮(4)的连结部(10a)、从连结部(10a)向轴向延伸的筒状部(10b)、以及从筒状部(10b)向内周侧延伸的支承部(10c)。摩擦盘(12)收纳在盖(10)的筒状部(10b)的内周,并被朝向飞轮(4)按压。锥形弹簧(14)由盖(10)的支承部(10c)支承,并将摩擦盘(12)朝向飞轮(4)施力。(The invention discloses a torque limiting device for accommodating components in a cover, thereby realizing radial and axial miniaturization. The torque limiting device (2) is provided with a cover (10), a friction disc (12), and a conical spring (14). The cover (10) has a connecting portion (10a) connected to the flywheel (4), a cylindrical portion (10b) extending in the axial direction from the connecting portion (10a), and a support portion (10c) extending to the inner peripheral side from the cylindrical portion (10 b). The friction disk (12) is housed on the inner periphery of the cylindrical portion (10b) of the cover (10) and is pressed toward the flywheel (4). The conical spring (14) is supported by a support portion (10c) of the cover (10) and biases the friction disk (12) toward the flywheel (4).)

1. A torque limiting device for limiting torque transmitted between a member on a power source side and a member on an output side, comprising:

a cover having a coupling portion coupled to a member on the power source side, a cylindrical portion extending in an axial direction from the coupling portion, and a support portion extending in an inner circumferential direction from the cylindrical portion;

a friction disk accommodated in an inner periphery of the cylindrical portion of the cover and pressed by a member facing the power source side; and

and a biasing member that is supported by the support portion of the cover and biases the friction disk toward the member on the power source side.

2. The torque limiting device of claim 1,

the coupling portion, the cylindrical portion, and the support portion of the cover are integrally formed by press molding.

3. Moment limiting device according to claim 1 or 2,

the torque limiter device further includes an annular pressure plate disposed axially between the friction disk and the force application member.

4. The torque limiting device of claim 3,

the urging member is a tapered spring disposed in a compressed state between the support portion of the cover and the pressure plate.

5. The torque limiting device of claim 4,

the support portion has an annular projection projecting toward the platen side,

the outer peripheral end of the conical spring is supported by the projection.

6. The torque limiting device according to any one of claims 1 to 5,

the torque limiter device further includes an annular damper plate disposed between the friction disk and the member on the power source side.

Technical Field

The present invention relates to a torque limiting device.

Background

In a hybrid vehicle using both an engine and an electric motor, a vibration damping device is provided between the engine and a drive unit on an output side to suppress rotational fluctuation of the engine. In such a vehicle, since the inertia amount on the output side is large, the amplitude of the torque fluctuation may become large and a large torque may be transmitted to the engine side at the time of engine start or the like.

Therefore, as shown in patent document 1, a vibration damping device provided with a torque limiter is proposed. The torque limiter of patent document 1 includes a friction disk, a pressure plate, and a conical spring. The flywheel is pressed by the conical spring through the pressure plate friction disk.

Disclosure of Invention

Technical problem to be solved by the invention

In the torque limiter of patent document 1, the friction disk, the pressure plate, and the conical spring are disposed in a recess formed in the flywheel. In addition, the conical spring is mounted in a compressed state between a plate fixed to the flywheel and the pressure plate.

In such a torque limiter, in order to avoid the need for a dedicated component of the flywheel, it is conceivable to provide a cover fixed to the flywheel and to house the components constituting the torque limiter inside the cover.

However, since the cover is usually integrally formed by press forming, an inclined surface is formed in the cylindrical portion formed by crimping. In addition, a curved surface portion is required at the bending portion. The diameter of the friction disk cannot be increased due to the inclined surface and the curved surface. On the contrary, in order to obtain a desired torque capacity, the apparatus cannot be miniaturized.

The technical problem of the present invention is to provide a torque limiting device for accommodating components in a cover, which can realize radial and axial miniaturization.

Means for solving the problems

(1) A torque limiter device according to the present invention is a device that limits torque transmitted between a member on a power source side and a member on an output side. The torque limiting device includes a cover, a friction disk, and an urging member. The cover has a coupling portion coupled to a member on the power source side, a cylindrical portion extending in the axial direction from the coupling portion, and a support portion extending in the inner circumferential direction from the cylindrical portion. The friction disk is accommodated in the inner periphery of the cylindrical portion of the cover and is pressed toward the power source side member. The urging member is supported by the support portion of the cover, and urges the friction disk toward the member on the power source side.

In this device, for example, when an excessive torque is input from the member on the output side, a slip is generated by the friction disk portion, and the excessive torque is prevented from being transmitted to the member on the power source side.

Here, the friction disk is disposed on the power source side inside the cover, and the friction disk is pressed against the member on the power source side by the biasing member supported by the support portion of the cover. Therefore, the friction disk is accommodated in a portion of the cover having a relatively large diameter in the cylindrical portion. Further, no curved surface portion is present in the outer peripheral portion of the friction disk. Therefore, the outer diameter of the friction disk can be increased. On the contrary, even if the diameter of the friction disk is reduced by a corresponding amount (increased amount), a required torque capacity can be obtained, and therefore, the radial dimension of the device can be reduced.

Further, since the biasing member is supported by the support portion of the cover, the support portion is elastically deformed. However, the restoring force against the elastic deformation of the support portion (the elastic force of the support portion) acts as a pressing force that presses the friction disk to the power source side together with the biasing member. Therefore, the thickness of the support portion of the friction disk can be made relatively thin, and the axial dimension of the device can be reduced.

Further, in this device, the torque limiter device can be easily attached to a general-purpose flywheel, that is, a flywheel that does not have a special shape for attaching the torque limiter.

(2) Preferably, the coupling portion, the cylindrical portion, and the support portion of the cover are integrally formed by press molding.

(3) Preferably, the brake device further includes an annular pressure plate disposed between the friction disk and the biasing member in the axial direction.

(4) Preferably, the urging member is a tapered spring disposed in a compressed state between the support portion of the cover and the pressure plate.

(5) Preferably, the support portion has an annular projection projecting toward the platen side, and an outer peripheral end portion of the conical spring is supported by the projection.

(6) Preferably, the brake device further includes an annular damper plate disposed between the friction disk and the power source side member.

ADVANTAGEOUS EFFECTS OF INVENTION

In the present invention as described above, the torque limiting device that houses the components inside the cover can be downsized in the radial direction and the axial direction.

Drawings

Fig. 1 is a cross-sectional view of a power transmission device including a torque limiter device according to an embodiment of the present invention.

Fig. 2 is a diagram showing the torque limiter apparatus of fig. 1.

Fig. 3 is a view showing the vibration damping device of fig. 1.

Fig. 4 is a diagram showing the hysteresis generating mechanism of fig. 1.

Fig. 5 is a front view of the vibration damping device shown in fig. 1 with a part broken away.

Fig. 6 is an external view of the hysteresis generating mechanism.

Fig. 7 is a diagram showing the magnitude of vibration generated by resonance of the intermediate rotating body and the magnitude of vibration of the present embodiment.

Description of the reference numerals

2 … torque limiting means; 10 … cover; 10a … joint; 10b … cylindrical part; 10c … support portion; 10d … curved surface portion; 10e … supporting protrusion; 11 … damping plate; 12 …: a friction disk; 13 … platen; 14 … conical spring.

Detailed Description

Fig. 1 is a sectional view of a power transmission device 1 including a vibration damping device according to an embodiment of the present invention, and fig. 2 is a front view of the power transmission device with a part of the power transmission device removed. The power transmission device 1 is mounted on, for example, a hybrid vehicle. The power transmission device 1 includes a torque limiter device 2 and a damper device 3 to which power from an engine is input via the torque limiter device 2. An engine is disposed on the right side of fig. 1, and a motor, a transmission, and the like are disposed on the left side. The O-O line of FIG. 1 is the axis of rotation.

[ Torque limiting device 2]

The torque limiter device 2 is coupled to a flywheel 4 to which power is input from the engine. Further, for example, when an excessive torque is input from the output side, the transmitted torque is limited to a predetermined value or less so as not to transmit the excessive torque to the engine side. The torque limiting device 2 has a cover 10, a damping plate 11, a friction disk 12, a pressure plate 13 and a conical spring 14. The friction disk 12, the pressure plate 13, and the conical spring 14 are housed inside the cover 10.

Fig. 2 shows the torque limiting device 2 in an enlarged manner. The cover 10 has a coupling portion 10a, a cylindrical portion 10b, and a support portion 10 c. The coupling portion 10a, the cylindrical portion 10b, and the support portion 10c are integrally formed by press molding. Therefore, the cylindrical portion 10b has an inclined surface formed by crimping, and is inclined toward the inner peripheral side as it is separated from the flywheel 4. Further, a curved portion 10d is formed between the cylindrical portion 10b and the support portion 10 c.

The coupling portion 10a is formed in a ring shape, and is coupled to the flywheel 4 via a bolt 15 with the damper plate 11 interposed therebetween. The cylindrical portion 10b extends from the inner peripheral end of the coupling portion 10a to the output side (the side away from the flywheel 4). The support portion 10c is annular and extends from the front end of the cylindrical portion 10b to the inner circumferential side by a predetermined width. An annular support protrusion 10e protruding toward the flywheel 4 is formed at a radially intermediate portion of the support portion 10 c.

The damper plate 11 is formed in a ring shape and has a plurality of holes 11a in an outer peripheral portion. The damper plate 11 is fixed to the side surface of the flywheel 4 together with the cover 10 by bolts 15 penetrating the holes 11 a. The outer diameter is the same as the outer diameter of the flywheel 4, and the inner diameter is smaller than the inner diameter of a friction material (described later) of the friction disk 12.

The friction disc 12 has a core plate 17 and a pair of friction materials 18. The core plate 17 has a plurality of fixing portions 17a formed in a ring shape and extending further radially inward from an inner peripheral end. The core plate 17 is coupled to the damper device 3 via the fixing portion 17 a. A pair of friction materials 18 are formed in a ring shape and fixed to both side surfaces of the core plate 17.

The pressure plate 13 is formed in a ring shape and is disposed opposite to the damping plate 11 with the friction disk 12 interposed therebetween. That is, the friction disk 12 is sandwiched between the damper plate 11 and the pressure plate 13. The inner diameter of the pressure plate 13 is smaller than the inner diameter of the friction material 18 of the friction disc 12.

The conical spring 14 is disposed in a compressed state between the pressure plate 13 and the support portion 10c of the cover 10. The outer peripheral portion of the conical spring 14 is supported by the supporting projection 10e of the supporting portion 10c, and the inner peripheral end abuts against the pressure plate 13, thereby pressing the pressure plate 13 to the flywheel 4 side.

With such a torque limiter device 2, when the torque transmitted between the engine side and the damper device 3 exceeds the torque transmission capacity set by the torque limiter device 2, a slip is generated in a part of the friction disk 12, and the transmitted torque is limited.

In the torque limiter device 2, the cylindrical portion 10b of the cover 10 has an inclined surface on the inner circumferential side as it is separated from the flywheel 4. Therefore, the diameter of the inner peripheral surface of the output-side end portion of the cylindrical portion 10b is smaller than that of the flywheel 4-side end portion. In addition, a curved surface portion 10d is formed at an end portion of the cylindrical portion 10 b. Therefore, if the friction disk 12 is disposed on the support portion 10c side, the diameter of the friction disk 12 cannot be secured large.

However, in the present embodiment, since the friction disk 12 is disposed on the flywheel 4 side inside the cover 10, the diameter of the friction disk 12 can be set to a larger diameter without being affected by the inclined surface of the cylindrical portion 10 b. On the contrary, the diameter of the torque limiter apparatus 2 having the same torque transmission capacity can be miniaturized.

In the present embodiment, the friction disk 12 is arranged to be pressed against the flywheel 4 via the damper plate 11. In contrast to the present embodiment, if the friction disk 12 is disposed on the support portion 10c side of the cover 10 and the conical spring 14 is disposed on the flywheel 4 side, the inner peripheral side of the support portion 10c of the cover 10 is elastically deformed so as to open outward. Then, the friction material 18 of the friction disk 12 comes into uneven contact with the support portion 10c, and a desired torque capacity cannot be obtained or the friction material 18 may be abnormally worn. In order to avoid such a problem, the thickness of the plate member constituting the lid 10 needs to be increased.

However, in this embodiment, the friction disk 12 is disposed on the flywheel 4 side and the conical spring 14 is disposed on the support portion 10c side of the cover 10, so that the surface (side surface of the damper plate 11) that abuts against the friction disk 12 is less likely to deform. Therefore, it becomes possible to make the entire friction material 18 of the friction disk 12 uniformly contact with the damping plate 11, and to obtain a stable torque capacity. In addition, abnormal wear of the friction material 18 of the friction disk 12 can be suppressed.

Here, although the support portion 10c of the cover 10 is also elastically deformed in the present embodiment, this elastic deformation acts as a force pressing the friction disk 12 together with the biasing force of the conical spring 14. Therefore, the thickness of the plate member constituting the lid 10 can be made thin. Therefore, the axial miniaturization of the torque limiter device 2 can be achieved.

In the torque limiter device 2 having the above-described configuration, the torque limiter device 2 can be easily attached to a general-purpose flywheel, that is, a flywheel that does not have a special shape for attaching a torque limiter.

[ damping device 3]

The damper device 3 transmits the power from the torque limiter device 2 to the output side, and also damps the vibration during power transmission. The vibration damping device 3 is extracted as shown in fig. 3. The damper device 3 includes an input-side rotating body 20, an output-side rotating body 21, a plurality of torsion springs 22, an intermediate rotating body 23, and a hysteresis generating mechanism 24.

< input-side rotating body 20>

The input-side rotating body 20 is rotatable about a rotation axis and has a first plate 31 and a second plate 32.

The first plate 31 has a circular plate portion 31a, a plurality of first window portions 31b for holding the torsion spring 22, a plurality of bent portions 31c, and a plurality of fixing portions 31d (see fig. 4). Fig. 4 shows a cross section of the vibration damping device 3 at a different circumferential position from that of fig. 1. The first plate 31 is positioned in the radial direction by the inner peripheral surface of the circular plate portion 31a and the outer peripheral surface of a cylindrical hub (described later) of the output-side rotating body 21.

The first window 31b is formed in the outer peripheral portion of the disc 31 a. The first window portion 31b has a long hole in the circumferential direction that penetrates in the axial direction, and a holding portion that is formed on the inner and outer peripheries of the hole and holds the torsion spring 22. The circumferential end surface of the hole can abut against the end surface of the torsion spring 22.

The bent portion 31c has an L-shaped cross section and is formed by bending the outer peripheral end of the circular plate portion 31a toward the flywheel 4. The rotational strength of the first plate 31 is improved by bending the outer peripheral end of the circular plate portion 31a into an L-shaped cross section.

As shown in fig. 4 and 5, the fixing portion 31d is formed by further bending the distal end of the bent portion 31c radially inward at the center portion of the bent portion 31c in the circumferential direction. Fig. 5 is a front view showing a device with a part of its components removed. A hole 31e for rivet fixing is formed in the fixing portion 31 d. A hole 31f for rivet fastening is formed in the disk portion 31a at the same position as the hole 31e for rivet fastening.

The second plate 32 is disposed axially opposite the first plate 31 on the flywheel 4 side of the first plate 31. The second plate 32 is formed in a circular plate shape and has a plurality of second window portions 32 b. The second plate 32 is positioned in the radial direction by its inner peripheral surface and an outer peripheral surface of a cylindrical hub (described later) of the output-side rotating body 21.

The second window portion 32b is formed at a position corresponding to the first window portion 31b of the first plate 31. The second window portion 32b has a long hole in the circumferential direction that penetrates in the axial direction, and a holding portion that is formed on the inner peripheral edge and the outer peripheral edge of the hole and holds the torsion spring 22. The circumferential end surface of the hole can abut against the end surface of the torsion spring. The torsion spring 22 is held by the second window portion 32b and the first window portion 31b of the first plate 31.

The second plate 32 has a hole 32e for rivet fixing at the same position as the hole 31e for rivet fixing of the first plate 31. The first plate 31 and the second plate 32 are fixed so as not to move in the axial direction and the circumferential direction by the rivet 33 passing through the rivet fixing holes 31e and 32e of the two plates 31 and 32. The fixing portion 17a of the core plate 17 of the friction disk 12 is inserted between the fixing portion 31d of the first plate 31 and the second plate 32, and the first plate 31, the second plate 32, and the friction disk 12 are fixed.

< output-side rotating body 21>

The output-side rotating body 21 is disposed between the first plate 31 and the second plate 32 in the axial direction. The output-side rotating body 21 is rotatable about a rotation axis and is rotatable relative to the first plate 31 and the second plate 32. The output-side rolling body 21 has a hub 35 and three flanges 36.

The hub 35 is disposed in the center of the output side rotor 21 and is cylindrical. A spline hole 35a is formed in the inner peripheral portion, and the spline hole 35a is spline-coupled to a shaft (not shown) formed on the output side. As described above, the outer peripheral surface of the hub 35 and the inner peripheral surfaces of the first plate 31 and the second plate 32 position the first plate 31 and the second plate 32 in the radial direction on the hub 35.

Three flanges 36 are formed to radially extend from the outer circumferential surface of the hub 35. The three flanges 36 are arranged at equal angular intervals in the circumferential direction. The flange 36 has a hysteresis mechanism mounting portion 36a, a first support portion 36b, and a second support portion 36 c. The hysteresis mechanism mounting portion 36a is a flat surface and is formed on the outer peripheral side of the hub 35. The first support portion 36b extends radially outward from the hysteresis mechanism mounting portion 36a, and is smaller in width in the circumferential direction than the hysteresis mechanism mounting portion 36 a. The spring seat 38 abuts both end surfaces in the circumferential direction of the first support portion 36 b. The second support portion 36c is formed by extending both end portions of the outer peripheral end of the first support portion 36b in the circumferential direction. The spring seat 38 abuts against the inner peripheral surface of the second support portion 36 c.

The second support portion 36c is disposed at the same position in the radial direction as the fixing portion 31d of the first plate 31. A hole 36d penetrating in the axial direction is formed in the second support portion 36 c. The first plate 31 is rivet-joined to the second plate 32 through the rivet-joining hole 31f passing through the hole 36d and the first plate 31.

< torsion spring 22>

The torsion spring 22 is accommodated between the plurality of flanges 36 of the output side rotating body 21 in the circumferential direction, and is held by the first window portion 31b and the second window portion 32b of the first plate 31 and the second plate 32. Two torsion springs 22 are disposed between adjacent flanges 36, and spring seats 38 are disposed on both end surfaces of each torsion spring 22.

< intermediate rotating body 23>

The intermediate rotating body 23 is rotatable about a rotation axis and is rotatable relative to the first plate 31, the second plate 32, and the output-side rotating body 21. The intermediate rotating body 23 is a member for operating the two torsion springs 22 arranged between the adjacent flanges 36 in series. The intermediate rotating body 23 has an annular portion 40 and three intermediate flanges 41.

The inner peripheral portion of the annular portion 40 is inserted into the outer periphery of the hub 35 of the output-side rotating body 21. That is, the intermediate rotary member 23 is positioned in the radial direction on the output side rotary member 21 by the inner peripheral surface of the annular portion 40 contacting the outer peripheral surface of the hub 35. The annular portion 40 is arranged axially parallel to the flange 36 of the output-side rotating body 21 on the flywheel 4 side of the flange 36.

The three intermediate flanges 41 have offset portions 41a, friction portions 41b, first support portions 41c, second support portions 41d, and stopper portions 41 e.

As shown in fig. 3 and 5, the offset portion 41a is a portion connecting the annular portion 40 and the friction portion 41 b. Here, both side surfaces of the friction portion 41b are at the same axial positions as both side surfaces of the flange 36 of the output-side rotator 21. That is, the friction portion 41b and the flange 36 of the output-side rotator 21 are located on a single plane on the side surface of the flywheel 4. In addition, the friction portion 41b and the flange 36 of the output-side rotating body 21 are located on the same plane on the output-side. The offset 41a connects the annular portion 40 and the friction portion 41b at different positions in the axial direction.

The first support portion 41c extends radially outward from the friction portion 41b, and is smaller in width in the circumferential direction than the friction portion 41 b. The spring seat 38 abuts both end surfaces in the circumferential direction of the first support portion 41 c. The second support portion 41d is formed by extending both end portions of the outer peripheral end of the first support portion 41c in the circumferential direction. The spring seat 38 abuts against the inner peripheral surface of the second support portion 41 d.

The stopper portion 41e is formed at the circumferential center portion of the outer peripheral surface of the first support portion 41c and projects radially outward. The stopper portion 41e is disposed at the center in the circumferential direction of the adjacent bent portion 31c of the first plate 31. The circumferential end surface of the stopper portion 41e can abut against the circumferential end surface of the bent portion 31 c.

That is, the relative rotation angle between the input side rotary body 20 and the intermediate rotary body 23 (or even the output side rotary body 21) is limited within a predetermined angular range by the bent portion 31c of the first plate 31 and the stopper portion 41e of the intermediate rotary body 23.

[ hysteresis generating mechanism 24]

The hysteresis generating mechanism 24 is disposed radially between the hub 35 of the output-side rotator 21 and the torsion spring 22. Further, the flange 36 (specifically, the hysteresis mechanism mounting portion 36a) of the output-side rotating body 21 and the intermediate flange 41 (specifically, the friction portion 41b) of the intermediate rotating body 23 are disposed between the first plate 31 and between the flange 36 of the output-side rotating body 21 and the intermediate flange 41 of the intermediate rotating body 23 and the second plate 32 in the axial direction.

As shown in fig. 4 and 6, the hysteresis generating mechanism 24 has two circular ring plates 45, two friction plates 46, and a conical spring 47. Since the two annular plates 45 and the two friction plates 46 are different in size, the respective plates 45, 46 on the first plate 31 side will be described here. Fig. 6 shows the output-side rotating body 21, the intermediate rotating body 23, and the hysteresis generating mechanism 24 with parts removed.

The annular plate 45 is formed in an annular shape and abuts against the side surfaces of the output-side rotating body 21 and the intermediate rotating body 23. The annular plate 45 is fixed to the hysteresis mechanism mounting portion 36a of the output side rotating body 21. Therefore, the ring plate 45 cannot rotate relative to the output side rotator 21, but can rotate relative to the intermediate rotator 23. Although not described in detail here, for example, a plurality of fixing portions of the annular plate 45 provided to protrude toward the inner circumferential side are fixed to the output-side rotating body 21 by rivets or the like.

The friction plate 46 is formed in a ring shape, and a side surface on the flywheel side abuts against the ring plate 45 and the other surface abuts against the first plate 31. Further, a plurality of engaging projections 46a projecting in the axial direction are formed on the surface of the friction plate 46 on the first plate 31 side. The engaging projection 46a is engaged with a hole 31g formed in the first plate 31. Thus, the friction plate 46 cannot rotate relative to the first plate 31, but can rotate relative to the annular plate 45.

As described above, the annular plate 45 and the friction plate 46 on the second plate 32 side are also configured similarly. The conical spring 47 is mounted in a compressed state between the friction plate 46 on the second plate 32 side and the second plate 32.

With the above configuration, when the input-side rotor 20 and the output-side rotor 21 rotate relative to each other and the torsion springs 22 expand and contract, frictional resistance (hysteresis moment) is generated between the friction plate 46 and the annular plate 45. When the torsion spring 22 expands and contracts and the output-side rotary member 21 and the intermediate rotary member 23 rotate relative to each other, a hysteresis moment is similarly generated. That is, the hysteresis generating mechanism 24 includes a hysteresis generating portion 24a (see fig. 4) that generates a hysteresis moment between the input-side rotating body 20 and the output-side rotating body 21, and a hysteresis generating portion 24b (see fig. 3) that gives a hysteresis moment to the intermediate rotating body 23.

[ actions ]

The power transmitted from the engine to the flywheel 4 is input to the damper device 3 via the torque limiter device 2. In the damper device 3, power is input to the first plate 31 and the second plate 32 of the friction disk 12 of the fixed torque limiting device 2, and the power is transmitted to the output side rotating body 21 via the torsion spring 22. Then, the power is further transmitted from the output side rotation body 21 to the output side motor, generator, transmission, and the like.

Further, for example, at the time of engine start, an excessive moment may be transmitted from the output side to the engine because the inertia amount on the output side is large. In such a case, the torque transmitted to the engine side is limited to a predetermined value or less by the torque limiting device 2.

In the damper device 3, when power is transmitted from the first plate 31 and the second plate 32 to the torsion spring 22, the torsion spring 22 is compressed. Further, the torsion spring 22 is repeatedly expanded and contracted by the torque variation. When the torsion spring 22 expands and contracts, torsion occurs between the first plate 31 and the second plate 32 and the output-side rotating body 21.

The hysteresis generating mechanism 24 operates by the torsion between the first plate 31 and the second plate 32 and the output-side rotating body 21, and generates a hysteresis moment. Specifically, since relative rotation is generated between the friction plate 46 fixed to the first plate 31 and the second plate 32 and the annular plate 45 fixed to the output-side rotator 21, frictional resistance is generated therebetween. This generates a hysteresis moment between the first plate 31 and the second plate 32 and the output-side rotating body 21.

Further, the torsion spring 22 expands and contracts to cause torsion between the output-side rotating body 21 and the intermediate rotating body 23. Due to this twisting, relative rotation is generated between the annular plate 45 fixed to the output side rotary body 21 and the friction portion 41b of the intermediate rotary body 23, and therefore frictional resistance is generated therebetween. This generates a hysteresis torque between the output-side rotating body 21 and the intermediate rotating body 23.

The intermediate rotating body 23 may vibrate largely due to resonance depending on the number of revolutions of the engine. However, in this embodiment, the large-amplitude vibration of the intermediate rotor 23 due to resonance can be suppressed by the hysteresis moment between the output-side rotor 21 and the intermediate rotor 23.

Fig. 7 is a diagram showing the magnitude of the vibration of the intermediate rotating body 23. The broken line M in fig. 7 indicates a case where the hysteresis torque is not applied to the intermediate rotating body 23, and the solid line M in the same figure indicates a case where the hysteresis torque is applied to the intermediate rotating body 23. As is clear from this figure, the magnitude of vibration due to resonance can be suppressed by applying a hysteresis moment to the intermediate rotating body 23.

When the torsion angles of the first plate 31 and the second plate 32 with respect to the output-side rotating body 21 and the intermediate rotating body 23 become larger, the end surface of the bent portion 31c of the first plate 31 comes into contact with the end surface of the stopper portion 41e of the intermediate rotating body 23. Therefore, the torsion angles of the first plate 31 and the second plate 32 with respect to the output-side rotating body 21 and the intermediate rotating body 23 can be suppressed from becoming equal to or larger than a predetermined angle. Therefore, excessive stress can be prevented from acting on the torsion spring 22.

[ other embodiments ]

The present invention is not limited to the embodiments described above, and various changes or modifications can be made without departing from the scope of the present invention.

(a) The structure of the hysteresis generating mechanism 24 is not limited to the embodiment. For example, when the resonance of the intermediate rotating body 23 does not become a problem, it is not necessary to bring the intermediate rotating body 23 into sliding contact with the annular plate 45.

(b) In the above embodiment, the annular plate 45 and the friction plate 46 are provided in the hysteresis generating mechanism 24, but the friction plate may be directly in contact with the output-side rotator 21 and the intermediate rotator 23.