JP2008008359A - Torque transmission device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a torque transmission device having simple and inexpensive construction for surely cutting off torque when exceeding an upper limit value and preventing the occurrence of noises and idling torque after cutting off the torque. <P>SOLUTION: The torque transmission device comprises: a retainer plate 28 having a protruded portion 34 formed with a plurality of slits 36 between a flange 26 connected to a driven shaft and itself; a mounting face 45 formed on a rotor 14 to be rotationally driven by the torque of a driving shaft and located outside the protruded portion 34 in view from the radial direction of the flange 26; a connection plate 38 having one end 40 rotatably locked to the mounting face 45 and the other end 44 located in the slit 36; a ball 50, a first hole 46 and a second hole 48 for detachably engaging the other end 44 of the connection plate 38 with the inner face of the slit 36 when the torque exceeds the upper limit value; and a pawl 54 formed on the retainer plate 28 for displacing the other end 44 of the connection plate 38 toward the radial outside of the flange 26 after cutting off the torque. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a torque transmission device, and more particularly to a torque transmission device having a torque limiter mechanism.

A torque transmission device having a torque limiter mechanism is used, for example, to transmit torque from an engine to a compressor of a vehicle air conditioner.
For example, the torque transmission device disclosed in Patent Document 1 includes an elastic member that is attached to a rotating shaft of a compressor via a hub. The elastic member has an annular base, an elastic bending portion, a sandwiched portion, a connecting portion, and a bent portion, and the sandwiched portion is located on the outer peripheral side of the elastic member and forms an arc shape. The sandwiched portion is disposed in a gap between the wear member and the holding plate that are respectively fixed to the pulley. Normally, when the sandwiched portion slides with the wear member, the rotation of the pulley is transmitted to the rotating shaft. The On the other hand, when the rotating shaft is braked and stopped due to overload during the rotation of the pulley, the outer peripheral portion of the elastic member comes out of the gap between the wear member and the holding plate, and the transmission of torque is interrupted.
Japanese Patent No. 3421619 (for example, paragraph number 0034, FIG. 1, FIG. 5, etc.)

However, in the case of the torque transmission device of Patent Document 1, even if the sandwiched portion of the elastic member is detached from between the pulley and the holding plate, the sandwiched portion vibrates due to the elasticity of the elastic member, and the retaining plate Repeat the collision. For this reason, after torque transmission is interrupted, a large noise is generated.
In addition, the sandwiched portion slides when it collides with the holding plate and rotates the holding plate. For this reason, torque transmission between the pulley and the rotating shaft is not completely interrupted, and idling torque is generated.

Further, in the case of this torque transmission device, since an elastic member made of a spring material is used, the material cost is high.
The present invention has been made in view of such a problem, and the object of the present invention is to ensure that the torque is reliably interrupted when the upper limit value is exceeded, and that noise and idling torque are also generated after the torque is interrupted. An object of the present invention is to provide a torque transmission device having a simple configuration that is prevented at a low cost.

  In order to achieve the above object, according to the present invention, in a torque transmission device for transmitting torque of a drive shaft to a driven shaft, a flange connected to the driven shaft and a flange fixed to the flange are fixed in parallel. A central plate, a pressing plate that protrudes radially from the outer edge of the central portion and forms a plurality of slits between the flange, a rotor that is driven to rotate by the torque of the drive shaft, and A mounting surface that is formed on the rotor and that is positioned outside the protruding portion when viewed in the radial direction of the flange, spans between the rotor and the pressing plate, and is rotatably locked to the mounting surface of the rotor. A plurality of strip-shaped connecting plates having one end and another end disposed in the slit, and the other end of the connecting plate is separated from the inner surface of the slit when the torque exceeds an upper limit value. An engaging means that engages with each other, and is formed on one of the flange and the holding plate, and the other end of the connecting plate is detached from the slit and the connecting plate rotates relative to the slit. Accordingly, there is provided a torque transmission device comprising a guide for displacing the other end portion of the connecting plate toward the radially outer side of the flange.

Preferably, the guide is a sawtooth claw integrally formed on an outer edge of a central portion of the pressing plate.
Preferably, the guide is a protrusion formed on the hub.
Preferably, the engaging means is formed in a ball, a first hole formed in the other end of the connecting plate, and a protruding portion of the pressing plate, and cooperates with the first hole. And a second hole for receiving the ball.

Preferably, the engaging means is formed in a protruding portion of the pressing plate, and receives the ball that has escaped from the second hole when a transmission torque exceeds an upper limit value, and also from the first hole. A third hole for allowing the ball to escape is further included (claim 5).
Preferably, the engaging means includes a protrusion formed at an end portion of the connecting plate and a hole formed at a protruding portion of the holding plate and receiving the protrusion of the connecting plate.

Preferably, the connecting plate has an arc shape.
Preferably, a friction material that slides with the other is disposed on one of the other end of the connecting plate and the protruding portion of the pressing plate.
Preferably, the other end portion of the connecting plate is subjected to a surface treatment for increasing and stabilizing the friction coefficient (claim 9).

  In the torque transmission device according to the first aspect of the present invention, when the torque exceeds the upper limit value, the other end of the connecting plate is detached from the slit, and the transmission of the torque is interrupted. Since the other end of the detached connecting plate is guided by the guide and displaced outward in the radial direction of the flange, the other end of the connecting plate does not collide with the protruding portion. As a result, in this torque transmission device, generation of noise and idling torque is prevented after the torque is interrupted.

In this torque transmission device, since the guide formed on the flange or the pressing plate is guided to the outside in the radial direction of the flange, the connecting plate does not need to have particularly great elasticity. That is, it is not necessary to use a spring material as the connecting plate. As a result, this torque transmission device is inexpensive.
In the torque transmission device according to the second aspect, since the guide is a sawtooth claw integrally formed on the outer periphery of the central portion of the pressing plate, the claw is easily formed when the pressing plate is molded.

In the torque transmission device according to the third aspect, since the guide is a protrusion formed integrally with the flange, the protrusion is easily formed when the flange is molded.
According to a fourth aspect of the present invention, the engaging means comprises first and second holes formed in the other end of the connecting plate and the protruding portion of the holding plate, and balls accommodated in these holes. . According to this engagement means, when the torque exceeds the upper limit, the ball comes out from the second hole, so that the engagement of the connecting plate with the protruding portion of the pressing plate is released with a simple configuration.

In the torque transmission device according to the fifth aspect, the engaging means has a third hole for receiving the ball that has come out from the second hole and letting the ball come out from the first hole. According to this engaging means, the ball is pulled out of the first hole and the second hole and accommodated in the third hole, so that the coupling plate is engaged with the protruding portion of the pressing plate while having a simple configuration. Is reliably released.
According to a sixth aspect of the present invention, the torque transmission device includes a protrusion formed at an end portion of the connecting plate and a hole formed in the protruding portion of the pressing plate and receiving the protrusion of the connecting plate. According to this engagement means, when the torque exceeds the upper limit, the protrusion comes out of the hole, so that the engagement of the connecting plate with the protruding portion of the pressing plate is released with a simple configuration.

  In the torque transmission device according to claim 7, since the connecting plate extends in an arc shape, even if the distance by which the other end of the connecting plate is displaced toward the radially outer side of the flange by the guide is short, the connecting plate side The edge is prevented from colliding with the protrusion of the holding plate. For this reason, in this torque transmission device, after the torque is interrupted, the other end of the connecting plate fits in a smaller circle as compared to the case where the connecting plate is linear. As a result, the torque transmission device can be downsized.

In the torque transmission device according to the eighth aspect, since the other end portion of the connecting plate and the protruding portion of the pressing plate slide through the friction material, torque transmission is reliably performed.
In the torque transmission device according to the ninth aspect, since the surface treatment for increasing and stabilizing the friction coefficient is performed on the other end portion of the connecting plate, the torque transmission is reliably performed.

FIG. 1 shows a torque transmission device according to an embodiment.
The torque transmission device is provided integrally with the compressor 2 of the vehicle air conditioning system, for example, and receives power from the engine 4 and transmits it to the compressor 2.
More specifically, the compressor 2 has a housing, and a compression unit 6 that performs refrigerant suction, compression, and discharge processes is accommodated in the housing. The housing has a cylindrical tube portion 8 on one end side, and an outer end portion of a rotating shaft (driven shaft) 10 extending from the compression unit 6 projects from the inside of the tube portion 8.

  The torque transmission device includes a bearing 12 fixed to the outer peripheral surface of the cylindrical portion 8 of the compressor 2, and the bearing 12 rotatably supports the rotor 14. The rotor 14 has an inner peripheral wall 16, an outer peripheral wall 18, and an annular end wall 20 that concentrically connects the inner peripheral wall 16 and the outer peripheral wall 18, and a belt groove 22 is formed on the outer peripheral surface of the outer peripheral wall 18. Has been. A belt is wound around the belt groove 22 between the pulley of the engine 4 and the power of the engine 4 is transmitted to the rotor 14 via the belt.

  On the other hand, the torque transmission device includes a boss 24 splined to the outer end portion of the rotating shaft 10, and a flange 26 is formed integrally with the boss 24. The flange 26 is separated from the cylindrical portion 8 of the compressor 2, the inner peripheral wall 16 and the end wall 20 of the rotor 14, and a pressing plate 28 is disposed between the flange 26 and the compressor 2. The holding plate 28 has a fitting hole that fits in the boss 24 at the center, and three rivet holes that are formed at equal intervals in the circumferential direction around the fitting hole.

The holding plate 28 is fixed to the flange 26 via three rivets 30 inserted through the rivet holes, and the portion (center portion 32) of the holding plate 28 inside the rivet 30 is in close contact with the flange 26. Or are arranged in parallel with a slight gap.
As shown in FIGS. 2 and 3, the pressing plate 28 has three protruding portions 34, and these protruding portions 34 protrude radially from the outer edge of the central portion 32 of the pressing plate 28 to the vicinity of the outer peripheral edge of the flange 26. ing. Here, as shown in FIG. 1, in the vicinity of the outer edge of the central portion 32, the root of the protruding portion 34 is bent, and the protruding portion 34 is part of the outer peripheral side of the flange 26 (opposing portion) with a predetermined interval. ) In parallel. Accordingly, each projecting portion 34 and its opposing portion form a slit 36 that opens to the outer side in the circumferential direction and the radial direction of the flange 26.

2 and 3 are front views of the torque transmission device, but FIG. 3 shows a state in which the flange 26 is removed.
Further referring to FIGS. 2 and 3, in order to transmit the rotation of the rotor 14 to the rotating shaft 10, there is a connecting plate 38 between the end wall 20 of the rotor 14 and each protrusion 34 of the pressing plate 28. It is laid over. Although the connecting plate 38 has a flat strip shape, the axis of the connecting plate 38 is bent in an arc shape. Bolt holes are formed in one end portion 40 on the end wall 20 side of each connecting plate 38, and one end portion 40 of the connecting plate 38 is fixed to the end wall 20 of the rotor 14 via a bolt 42 inserted through the bolt hole. ing.

The tightening force of the bolt 42 is set so that the connecting plate 38 can rotate around the shaft portion of the bolt 42.
On the other hand, the other end 44 of each connecting plate 38 on the projecting portion 34 side is located in the slit 36, that is, between the projecting portion 34 and the facing portion of the flange 26.
One end portion 40 of each connecting plate 38 is fixed to the upper surfaces (mounting surfaces 45) of three columnar bases formed so as to protrude from the end wall 20 of the rotor 14. Each mounting surface 45 is located on the outer side of the protruding portion 34 when viewed in the radial direction of the flange 26, and is located at substantially the same position as the rivet 30 when viewed in the circumferential direction of the flange 26. The mounting surface 45 is located at substantially the same position as the protruding portion 34 when viewed in the axial direction of the flange 26, and each connecting plate 38 extends parallel to the flange 26.

Further, one end portion 40 of each connecting plate 38 is positioned outside the rivet 30 when viewed in the radial direction of the flange 26, and the other end portion 44 forming a pair is located in the slit 36 behind the rivet 30 when viewed in the rotational direction R. Is arranged. For this reason, when the other end portion 44 is in the slit 36, each connecting plate 38 extends spirally and crosses the outer peripheral edge of the flange 26 diagonally.
The other end portion 44 of each connecting plate 38 is detachably engaged with the inner surface of the slit 36, that is, the projecting portion 34 or the opposing portion of the flange 26 thereof.

  More specifically, referring to FIG. 4, a first hole 46 is formed in the other end portion 44 of the connecting plate 38, and a second hole is formed in the projecting portion 34 so as to match the first hole 46. 48 is formed. The first hole 46 and the second hole 48 cooperate with each other to accommodate one ball 50. The opening diameter of the second hole 48 on the surface on the flange 26 side is smaller than the diameter of the ball 50 so that only a part of the ball 50 is received, and the inner peripheral surface on the flange 26 side of the second hole 48. Is tapered.

  Further, a third hole 52 is formed in the projecting portion 34 so as to be separated from the second hole 48, and the third hole 52 is located in front of the second hole 48 when viewed in the rotational direction R of the rotor 14. positioned. The opening diameter of the third hole 52 on the surface on the flange 26 side is larger than the opening diameter of the second hole 48 and further larger than the diameter of the ball 50. In order to prevent the ball 50 from falling off, the opening diameter of the third hole 52 on the surface opposite to the flange 26 is smaller than the diameter of the ball 50. For this reason, the inner peripheral surface of the third hole 52 is tapered.

Further, referring again to FIGS. 2 and 3, in this torque transmission device, three claws 54 are integrally formed on the pressing plate 28. Each claw 54 is located between the projecting portions 34 and continues to the outer edge of the central portion 32 of the pressing plate 28. Each claw 54 has a sawtooth shape, and the outer edge of the claw 54 extends in a spiral shape.
In other words, the outer edge of the claw 54 is located on the side of the protrusion 34 positioned rearward in the rotation direction R, and is positioned on the radially inner side of the tip of the protrusion 34, and is positioned forward of the rotation direction R. On the 34th side, it is located radially outside the outer peripheral edge of the flange 26.

As shown in FIG. 5, the claw 54 is formed flush with the central portion 32 of the flange 36. Therefore, when viewed in the axial direction of the rotary shaft 10, the position of the outer edge of the claw 54 is the connecting plate. Equal to position 38.
Hereinafter, the operation of the above-described torque transmission device will be described.
The torque transmission device receives the power of the engine 4 and rotates the rotating shaft 10 of the compressor 2 with the received power.

That is, when the rotor 14 is rotationally driven by the belt, the holding plate 28 is pulled in the rotation direction R by the connecting plate 38. As a result, the pressing plate 28 and the flange 26 to which the pressing plate 28 is fixed by the rivet rotate. When the flange 26 rotates, the boss 24 integrated with the flange 26 also rotates, and the rotary shaft 10 splined with the boss 24 rotates.
In the compressor 2, as the rotary shaft 2 rotates, the compression unit 6 performs a refrigerant gas suction process as a working fluid, a suction refrigerant gas compression process, and a compressed refrigerant gas discharge process.

Thus, although the torque transmission device forms a torque transmission path between the engine 4 and the compressor 2, for example, the torque transmitted by the rotating shaft 10 of the compressor 2 being stopped due to an abnormality such as seizure. When the value rises abnormally, the transmission path is cut off by itself.
That is, when the rotating shaft 10 is stopped and the connecting plate 38 pulls the holding plate 28 and a torque exceeding the upper limit is applied to the ball 50, the ball 50 comes out of the second hole 48. As a result, the engagement state between the protruding portion 34 of the pressing plate 28 and the other end portion 44 of the connecting plate 38 is released, and torque transmission is interrupted.

  The ball 50 that has come out is further pulled by the connecting plate 38 and buried in the third hole 52. After the ball 50 is buried in the third hole 52, the other end 44 of the connecting plate 38 comes out of the slit 36. Thereafter, in the vicinity of the other end portion 44, the outer edge of the claw 54 comes into contact with the inner edge of the connecting plate 38, and the outer edge of the claw 54 moves relatively along the inner edge of the connecting plate 38, thereby connecting the connecting plate 38. The other end 44 is smoothly displaced toward the radially outer side of the flange 26. Thus, when the other end 44 of the connecting plate 38 passes the outer edge of one claw 54 once, the connecting plate 38 is disposed along the outer peripheral edge of the flange 26 with a predetermined gap.

Thus, after the torque is interrupted, the other end 44 of the connecting plate 38 is guided by the claw 54 as a guide and is displaced radially outward of the flange 26. The vicinity of the one end 44 does not collide with the protrusion 34. As a result, in this torque transmission device, generation of noise and idling torque is prevented after the torque is interrupted.
Further, in this torque transmission device, the other end 44 of the connecting plate 38 is guided radially outward of the flange 26 by the claw 54 formed on the holding plate 28, so that the connecting plate 38 has particularly great elasticity. There is no need to be. That is, it is not necessary to use a spring material as the connecting plate 38. As a result, this torque transmission device is inexpensive.

Since the claw 54 is integrally formed on the outer periphery of the central portion 32 of the pressing plate 28, it is easily formed when the pressing plate 28 is molded.
Furthermore, in the torque transmission device described above, the engaging means for detachably engaging the other end 44 of the connecting plate 38 with the inner surface of the slit 36 is the other end 44 of the connecting plate 38 and the protruding portion 34 of the holding plate 28. The first and second holes 46 and 48 formed in the first and second holes 46 and 48, and the balls 50 accommodated in the holes 46 and 48. According to this engagement means, when the torque exceeds the upper limit, the ball 50 is pulled out from the second hole 48, whereby the engagement of the connecting plate 38 with the protruding portion 34 is released with a simple configuration.

  Furthermore, in this torque transmission device, the engaging means has a third hole 52 that receives the entire ball 50 that has slipped out of the second hole 48 and allows the ball 50 to slip out of the first hole 46. According to this engaging means, the ball 50 comes out of the first hole 46 and the second hole 48 and is accommodated in the third hole 52, so that the connecting plate 38 for the projecting portion 34 can be obtained with a simple configuration. Is reliably released.

The present invention is not limited to the above-described embodiments, and various modifications can be made.
In one embodiment, the one end 40 of the connecting plate 38 is rotatably locked to the end wall 20 of the rotor 14 by the bolt 42, but a pin, a rivet, or the like may be used instead of the bolt 42.
In one embodiment, the claw 54 functions as a guide. However, instead of the claw 54, protrusions 56a and 56b may be formed on the flange 26 as shown in FIGS. The protrusions 56a and 56b are located between the protrusions 34 and are separated from each other in the circumferential direction. Further, when viewed in the rotation direction R, the protrusion 56a on the rear protrusion 34 side is located radially inward of the protrusion 56b on the front protrusion 34 side.

In this case, after the torque is interrupted, the protrusions 56a and 56b are sequentially brought into contact with the other end portion 44 side of the connecting plate 38, and the other end portion 44 is pushed out radially outward. The protrusions 56a and 56b are easily formed when the flange 26 is molded.
In order to smoothly push out the other end portion 44, the guide is preferably in contact with the connecting plate 38 in the vicinity of the other end portion 44 away from the one end portion 40 of the connecting plate 38.

  In one embodiment, the ball 50 is used as a means for detachably engaging the protruding portion 34 of the pressing plate 28 and the other end portion 44 of the connecting plate 38, but as shown in FIG. Instead, a hemispherical protrusion 58 may be formed on the other end 44 of the connecting plate 38. In this case, when the second hole 48 receives the protrusion 58, the protruding portion 34 of the pressing plate 28 and the other end portion 44 of the connecting plate 38 are detachably engaged. Then, when the torque exceeds the upper limit, the protrusion 58 comes out from the second hole 48, so that the engagement of the connecting plate 38 with the pressing plate 28 is released with a simple configuration.

  In one embodiment, the connecting plate 38 is arcuate and the axis of the connecting plate 38 is curved with a radius of curvature slightly larger than the radius of curvature of the outer periphery of the flange 26, but the connecting plate 38 is linear. It may extend to. However, as in the embodiment, when the connecting plate 38 has an arc shape, even if the distance by which the other end portion 44 of the connecting plate 38 is displaced toward the radially outer side of the flange 26 by the claw 54 is short. Thus, the side edge of the connecting plate 38 is prevented from colliding with the protruding portion 34 of the pressing plate 28. For this reason, when the connecting plate 38 has an arc shape, the other end portion 44 of the connecting plate 38 fits in a smaller circle after the torque is interrupted, compared to a case where the connecting plate 38 has a linear shape. As a result, when the connecting plate 38 has an arc shape, the torque transmission device can be downsized.

  In one embodiment, the other end 44 of the connecting plate 38 and the protrusion 34 of the holding plate 28 slide directly, but as shown in FIG. 10, the other end 44 of the connecting plate 38 and the holding plate The friction plate 60 may be disposed on one of the 28 protruding portions 34, and the other and the friction material 60 may be slid. In this case, since the other end portion 44 of the connecting plate 38 and the protruding portion 34 of the pressing plate 28 slide through the friction material 60, torque transmission is reliably performed.

  Further, instead of or in combination with the friction material 60, as shown in FIG. 11, the friction coefficient is increased and increased at the other end portion 44 of the connecting plate 38 or the protruding portion 34 of the pressing plate 28. A roughened surface 62 may be formed by performing a surface treatment for stabilization. Specifically, shot blasting, friction material spraying, or the like may be performed. Also in this case, torque transmission is reliably performed by increasing the friction coefficient of the other end portion 44 of the connecting plate 38.

  Finally, it goes without saying that the torque transmission device of the present invention can be applied to devices other than the compressor 2.

It is a longitudinal section of a torque transmission device of one embodiment of the present invention applied to a compressor of an air conditioning system for vehicles. It is a front view of the torque transmission apparatus of FIG. It is a figure which shows the state which removed the flange from the torque transmission apparatus of FIG. It is sectional drawing which follows the IV-IV line of FIG. It is sectional drawing which follows the VV line of FIG. It is a front view which shows the state after the torque interruption of the torque transmission apparatus of FIG. It is a front view of the torque transmission device of FIG. 1 to which a guide of a modification is applied. It is sectional drawing for demonstrating the guide of a modification. It is sectional drawing for demonstrating the engaging means of the other end part of the connection board which concerns on a modification, and the protrusion part of a pressing board. It is sectional drawing for demonstrating the state which has arrange | positioned the friction board between the other end part of a connection plate, and the protrusion part of a pressing board. It is a top view for demonstrating the connection board which concerns on a modification.

Explanation of symbols

14 Rotor
26 Flange
28 Presser plate
34 Protrusion
36 slits
38 Connecting plate
44 other end
45 Mounting surface
46 1st hole (engagement means)
48 Second hole (engagement means)
50 balls (engagement means)
52 3rd hole (engagement means)
54 Nail (guide)

Claims (9)

In the torque transmission device that transmits the torque of the drive shaft to the driven shaft,
A flange connected to the driven shaft;
A central portion fixed in parallel to the flange, and a pressing plate having a protruding portion that radially protrudes from an outer edge of the central portion and forms a plurality of slits between the flange,
A rotor driven to rotate by the torque of the drive shaft;
A mounting surface formed on the rotor and positioned on the outer side of the projecting portion in the radial direction of the flange;
A plurality of strip-shaped connecting plates that are spanned between the rotor and the pressing plate and that are rotatably locked to the mounting surface of the rotor and the other end disposed in the slit;
Engaging means for releasably engaging the other end of the connecting plate with respect to the inner surface of the slit when the torque exceeds an upper limit;
The other end of the connecting plate is formed on one of the flange and the holding plate, and the other end of the connecting plate is separated from the slit and the connecting plate rotates relative to the slit. A torque transmission device comprising: a guide that is displaced toward a radially outer side of the flange.   2. The torque transmission device according to claim 1, wherein the guide is a serrated claw integrally formed on an outer edge of a central portion of the pressing plate.   The torque transmission device according to claim 1, wherein the guide is a protrusion formed on the hub.   The engaging means is formed in a ball, a first hole formed in the other end of the connecting plate, and a protruding portion of the holding plate, and accommodates the ball in cooperation with the first hole. The torque transmission device according to any one of claims 1 to 3, further comprising a second hole.   The engaging means is formed at a protruding portion of the presser plate, receives the ball that has escaped from the second hole when the transmission torque exceeds an upper limit value, and also escapes the ball from the first hole. The torque transmission device according to claim 4, further comprising a third hole.   The engagement means includes a protrusion formed at an end portion of the connecting plate and a hole formed in a protruding portion of the holding plate and receiving the protrusion of the connecting plate. The torque transmission device according to any one of the above.   The torque transmission device according to claim 1, wherein the connecting plate has an arc shape.   The torque transmission device according to any one of claims 1 to 7, wherein a friction material that slides on the other is disposed on one of the other end of the connecting plate and the protruding portion of the pressing plate. .   The torque transmission device according to any one of claims 1 to 8, wherein a surface treatment for increasing and stabilizing a friction coefficient is applied to the other end portion of the connecting plate.

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