JP7206626B2 - friction fastening device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction engagement device applied to clutches and brakes in automatic transmissions of automobiles.

2. Description of the Related Art Conventionally, frictional engagement devices such as clutches and brakes in automatic transmissions of automobiles are driven by hydraulic pressure from a hydraulic pump, which increases the weight and size of the automatic transmission. In order to reduce the weight and size of an automatic transmission that uses a friction coupling device, it is necessary to reduce the size of the hydraulic pump by adopting a booster mechanism that generates a large coupling force with a small amount of hydraulic pressure, and to use an electric actuator. It is effective to use no hydraulic pressure.

The former booster mechanism has not been adopted conventionally. This is because in the conventional structure in which the piston presses a plurality of friction plates provided between the drum and the hub, the driving direction of the piston and the pressing direction of the friction plates are the same. This is because it is not possible to increase the pressing force of

As the latter electric actuator, Patent Document 1 discloses a polymer actuator element in which conductive polymer tubes are bundled and spirally wound and housed in a space defined by a cylindrical cylinder and a cylindrical piston. A clutch device using an actuator has been proposed. However, it is difficult to effectively convert the expansion/contraction force of the conductive polymer tube into the actuation force of the actuator.

Patent Documents 2 and 3 propose a clutch device using a polymer actuator in which an elastic container in which a gel-like electroresponsive volume phase transition polymer and an electrolyte are enclosed is housed between a cylinder and a piston. . However, since this product encloses a gel-like polymer and an electrolyte in an elastic container, it has a problem of lacking in durability.

Due to such conventional problems, the use of electric actuators in frictional fastening devices has not been put to practical use. Electrical actuators include piezoelectric (piezoelectric ceramic) and dielectric (polymer actuators). The piezoelectric type has a large pressing force but a small displacement, and the dielectric type has a large amount of displacement but a small pressing force. Therefore, in order to apply them to frictional fastening devices such as clutches and brakes, piezoelectric actuators are required to have a mechanism for increasing displacement, and dielectric actuators are required to have a boosting mechanism.

JP-A-2005-83466 JP 2005-155871 A JP 2011-106564 A

SUMMARY OF THE INVENTION It is an object of the present invention to provide a frictional fastening device that can secure an increase in pressing force and can be made lighter and more compact.

In order to solve the above problems, the present invention takes the following measures.

In the invention of claim 1,
A friction fastening device comprising friction surfaces facing each other provided on a drum and a hub, and pressing force generating means for generating a pressing force acting on the friction surfaces,
The friction surface is
a first friction surface provided on the drum and inclined with respect to the axial direction of the drum;
a second friction surface provided on the hub, inclined with respect to the axial direction of the hub, and opposed to the first friction surface;
wherein the hub is axially movably provided with respect to the drum;
The pressing force generating means is configured to generate a pressing force against the hub in the axial direction of the hub to move the hub in the axial direction,
A pressing member is provided for axially pressing the hub,
The pressing force generating means is composed of a polymer actuator composed of two electrode plates and a polymer member interposed between the two electrode plates, and the outer peripheral edge of one electrode plate is formed on the drum. The inner peripheral edge of the electrode plate on the other side is coupled to the pressing portion formed on the pressing member.

In the invention of claim 2,
A friction fastening device comprising friction surfaces facing each other provided on a drum and a hub, and pressing force generating means for generating a pressing force acting on the friction surfaces,
The friction surface is
a first friction surface provided on the drum and inclined with respect to the axial direction of the drum;
a second friction surface provided on the hub, inclined with respect to the axial direction of the hub, and opposed to the first friction surface;
wherein the hub is axially movably provided with respect to the drum;
The pressing force generating means is configured to generate a pressing force against the hub in the axial direction of the hub to move the hub in the axial direction,
the hub is spline-engaged with a first hub having a first tubular portion and a second tubular portion having a diameter smaller than that of the first tubular portion, and the first tubular portion or the second tubular portion of the first hub; a second hub having the second friction surface;
The pressing force generating means is composed of a polymer actuator including two electrode plates and a polymer member interposed between the two electrode plates, and one electrode plate is formed on the second hub. The electrode plate on the other side is connected to a connecting portion formed in the first cylindrical portion and the second cylindrical portion of the first hub to which the second hub is not spline-connected.

In the invention of claim 3 , a plurality of the polymer actuators are provided in the axial direction.

In the invention of claim 4 , at least one of the plurality of pressing portions and the plurality of connecting portions to which the two electrode plates of the polymer actuator are connected is formed in a stepped shape widening toward the anti-friction plate side. ing.

In the invention of claim 5 ,
It is configured to press the plurality of pressing portions by a contraction operation caused by applying a voltage to the polymer actuator.

In the invention of claim 6 ,
A friction fastening device comprising friction surfaces facing each other provided on a drum and a hub, and pressing force generating means for generating a pressing force acting on the friction surfaces,
The friction surface is
a first friction surface provided on a first friction plate provided on the drum and perpendicular to the axial direction of the drum;
a second friction surface provided on a second friction plate provided on the hub, perpendicular to the axial direction of the hub and opposed to the first friction surface;
The pressing force generating means has a pressing member provided with a pressing surface inclined with respect to the pressing force generating direction,
The pressing surface of the pressing member presses the first friction plate or the second friction plate in the axial direction of the drum or hub .

In the invention of claim 7 , the pressing force generating means is composed of a polymer actuator comprising two electrode plates and a polymer member interposed between the two electrode plates,
The pressure member is displaced by an extension operation in the plane direction of the polymer member when the polymer actuator is contracted by applying a voltage.

According to the eighth aspect of the invention, the polymer actuator is configured such that one of the two electrode plates is positioned on the drum such that the pressing surface of the pressing member is parallel to the first friction plate and the second friction plate. is fixed to

In the ninth aspect of the invention, the first friction plate is provided with a pressing force receiving portion inclined with respect to the axial direction of the drum that is in sliding contact with the pressing surface of the pressing member of the polymer actuator,
One of the two electrode plates of the polymer actuator is fixed to the drum so that the pressing surface of the pressing member is parallel to the pressing force receiving portion of the first friction plate.

According to the first aspect of the invention, the direction in which the pressing force is generated by the polymer actuator is different from the direction in which the pressing force acting perpendicularly to the friction surface acts. Thereby, the pressing force acting on the friction surface can be increased by the action of the wedge. Therefore, it is possible to secure an increase in the pressing force of the polymer actuator, which has a large displacement but a small pressing force. As a result, the frictional fastening device can be made hydraulicless, and drive resistance can be reduced, and weight reduction and compactness can be achieved.

According to the second aspect of the invention, the direction in which the pressing force is generated by the polymer actuator is different from the direction in which the pressing force acting perpendicularly to the friction surface acts. Thereby, the pressing force acting on the friction surface can be increased by the action of the wedge. Therefore, it is possible to secure an increase in the pressing force of the polymer actuator, which has a large displacement but a small pressing force. As a result, the frictional fastening device can be made hydraulicless, and drive resistance can be reduced, and weight reduction and compactness can be achieved.

According to the third aspect of the present invention, the pressing force of a polymer actuator having a large displacement but a small pressing force can be increased by the number of polymer actuators.

According to the fourth aspect of the invention, since the plurality of connecting portions and the plurality of pressing portions are widened toward the side opposite to the friction plate, the plurality of polymer actuators can be sequentially assembled, facilitating assembly. Become. In addition, the polymer members of the plurality of polymer actuators can be increased as they are separated in the direction opposite to the friction plate, and the pressing force of the pressing portion can be further increased.

According to the invention of claim 5 , a large pressing force can be applied to the pressing portion by the contraction operation with a large force generated by the polymer actuator, and the pressing force of the pressing portion can be further increased.

According to the invention of claim 6 , the first friction plate or the second friction plate is pressed in the axial direction of the drum or hub by the pressing surface of the pressing member that is inclined with respect to the direction in which the pressing force is generated. Since the pressing force is applied to the friction surface consisting of the first friction surface and the second friction surface perpendicular to the direction, the direction in which the pressing force is generated by the pressing force generating means and the direction in which the pressing force acting perpendicularly to the friction surface acts. is different. Thereby, the pressing force acting on the friction surface can be increased by the action of the wedge. Therefore, the pressing force generating means can generate a small pressing force, and the frictional engagement device and the automatic transmission using the same can be made lighter and more compact.

According to the invention of claim 7 , the pressing force due to the stretching action in the surface direction of the polymer member is utilized. The pressing force due to the expansion in the plane direction is smaller than the pressing force due to the contraction in the thickness direction, but the direction in which the pressing force is generated due to the expansion in the plane direction is different from the direction in which the pressing force acts perpendicular to the friction surface. Therefore, the pressing force acting on the friction surface can be increased by the action of the wedge.

According to the eighth aspect of the invention, the pressing surface of the pressing member is parallel to the first friction plate and the second friction plate, and directly presses the first friction plate, so that the arrangement and construction can be simplified.

According to the ninth aspect of the invention, the pressing surface of the pressing member is parallel to the pressing force receiving portion of the first friction plate inclined with respect to the axial direction of the drum. The two friction plates can be arranged in parallel, which facilitates the arrangement of the polymer actuator.

1 is a schematic diagram of an automatic transmission to which a frictional engagement device of the present invention is applied; FIG. FIG. 2 is a cross-sectional view showing the non-engagement state (a) and the engagement state (b) of the frictional engagement device of the first embodiment applied to the clutch. FIG. 3 is an exploded perspective view of a piston and a polymer actuator of a friction fastening device; FIG. 4 is an enlarged cross-sectional view showing (a) before voltage application and (b) after voltage application of the polymer actuator. The perspective view which shows the modification of a polymer actuator. Sectional drawing which shows the non-engagement (a) and engagement (b) states of the frictional engagement device of 2nd Embodiment applied to a clutch. FIG. 11 is an enlarged cross-sectional view showing another modification of the polymer actuator before (a) and after (b) voltage application; Sectional drawing which shows the state (a) at the time of non-fastening of the friction fastening device of 3rd Embodiment, and the time (b) at the time of fastening. The side view seen from the polymer actuator side of Fig.8 (a). Sectional drawing which shows the state (a) at the time of non-fastening of the friction fastening device of 4th Embodiment, and the time (b) at the time of fastening.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

<Configuration of automatic transmission>
First, the configuration of an automatic transmission in which the frictional engagement device of the present invention is used will be described with reference to FIG. This automatic transmission 1 is applied to a vehicle with a transverse engine such as a front engine front drive vehicle. A transmission mechanism 5 to which rotation is input via an input shaft 4 is provided, and the transmission mechanism 5 is housed in a transmission case 6 while being arranged on the axis of the input shaft 4 .

The output rotation of the speed change mechanism 5 is transmitted to the differential gear 9 through the counter drive mechanism 8 from the output gear 7 arranged in the middle of the input shaft 4 on the axis of the input shaft 4, Left and right axles 9a and 9b are driven.

The torque converter 3 includes a case 3a connected to the engine output shaft 2, a pump 3b fixed in the case 3a, and a pump 3b disposed opposite the pump 3b and driven by the pump 3b via hydraulic oil. a stator 3e interposed between the pump 3b and the turbine 3c and supported by the transmission case 6 via a one-way clutch 3d to increase torque; the case 3a and the turbine; 3c and directly connects the engine output shaft 2 and the turbine 3c via the case 3a. Rotation of the turbine 3c is transmitted to the transmission mechanism 5 via the input shaft 4. As shown in FIG.

On the other hand, the transmission mechanism 5 has first, second and third planetary gear sets (hereinafter simply referred to as "first, second and third gear sets") 10, 20 and 30, which are housed in the transmission case 6. are arranged in order from the torque converter side on the anti-torque converter side of the output gear 7 in .

As friction elements constituting the transmission mechanism 5, a first clutch 40 and a second clutch 50 are arranged on the torque converter side of the output gear 7, and a second clutch 40 and a second clutch 50 are arranged on the side of the output gear 7 opposite to the torque converter. A first brake 60 , a second brake 70 and a third brake 80 are arranged in order from the torque converter side, and a one-way clutch 90 is arranged in parallel with the first brake 60 .

The first, second and third gear sets 10, 20 and 30 are all single pinion type planetary gear sets, and include sun gears 11, 21 and 31 and respective gears meshing with these sun gears 11, 21 and 31. It comprises a plurality of pinions 12, 22, 32, carriers 13, 23, 33 supporting these pinions 12, 22, 32, respectively, and ring gears 14, 24, 34 meshing with the pinions 12, 22, 32 respectively. ing.

The input shaft 4 is connected to the sun gear 31 of the third gear set 30, the sun gear 11 of the first gear set 10, the sun gear 21 of the second gear set 20, and the ring gear 14 of the first gear set 10 and the second gear set 20. The carrier 23, the ring gear 24 of the second gear set 20 and the carrier 33 of the third gear set 30 are respectively connected. The output gear 7 is connected to the carrier 13 of the first gear set 10 .

The sun gear 11 of the first gear set 10 and the sun gear 21 of the second gear set 20 are connected to the input shaft 4 via the first clutch 40 so as to be connectable and disconnectable. It is connected to the input shaft 4 via the second clutch 50 so as to be connectable/disconnectable.

Further, the ring gear 14 of the first gear set 10 and the carrier 23 of the second gear set 20 are connected to the transmission case 6 so as to be connected and disconnected via the first brake 60 and the one-way clutch 90 arranged in parallel, The ring gear 24 of the second gear set 20 and the carrier 33 of the third gear set 30 are detachably connected to the transmission case 6 via the second brake 70. Further, the ring gear 34 of the third gear set 30 is It is connected to the transmission case 6 via the third brake 80 so as to be connectable/disconnectable.

With the above configuration, according to this transmission mechanism 5, six forward speeds and reverse and are obtained. It should be noted that the first brake 60 is engaged only in the 1st gear that operates the engine brake, and in the 1st gear that does not operate the engine brake, the one-way clutch 90 is locked to form the 1st gear.

<First embodiment of friction fastening device>
Next, an embodiment of a frictional engagement device 100A applied to the first clutch 40 and the second clutch 50 of the automatic transmission 1 will be described. Since the frictional engagement device 100A applied to the first clutch 40 and the second clutch 50 have basically the same structure, the frictional engagement device 100A applied to the first clutch 40 will be described with reference to FIG.

The first clutch 40 has a drum 41 and a hub 42 .

The drum 41 has a shaft portion 41 a connected to the input shaft 4 and rotates together with the input shaft 4 . The drum 41 has an annular end wall 41b on the side opposite to the shaft portion 41a. A cylindrical portion 41c is formed on the inner surface of the end wall 41b so as to be radially inwardly spaced from the inner surface of the drum 41 . A first friction surface 101a is formed on the inner surface of the drum 41 and the inner surface of the tubular portion 41c. The first friction surface 101a is inclined with respect to the axial direction of the drum 41 so that the diameter increases from the end wall 41b toward the hub.

The hub 42 is composed of a first hub 42a and a second hub 42b. The first hub 42a has a diameter smaller than that of the tubular portion 41c of the drum 41 and is arranged inside the drum 41 concentrically therewith. The first hub 42a has a shaft portion 42c connected to the sun gears 11 and 21 of the first gear set 10 and the second gear set 20, and rotates together with the sun gears 11 and 21. As shown in FIG. The second hub 42b has a tubular shape, is spline-connected to the outer periphery of the first hub 41a, and is axially movable with respect to the drum 41 and the first hub 42a. The second hub 42b has an end wall 42d on the side opposite to the shaft portion 42c of the first hub 42a. A cylindrical portion 42e is formed on the inner surface of the end wall 42d, spaced apart from the outer surface of the second hub 42b. A second friction surface 101b is formed on the outer surface of the second hub 42b and the outer surface of the tubular portion 42e. The second friction surface 101b is inclined at the same angle as the first friction surface 101a with respect to the axial direction of the hub 42 so that the diameter decreases from the end wall 42d toward the drum. It faces the first friction surface 101a via the provided facing material 42f.

A frictional fastening device 100A is provided between the drum 41 and the hub 42 . The friction fastening device 100A includes a first friction surface 101a of the drum 41, a second friction surface 101b of the hub 42, and a pressing member 102 (hereinafter referred to as the present invention) that presses the second hub 42b having the second friction surface 101b. (referred to as a “piston” in the embodiment) , and first, second and third polymer actuators 103a, 103b and 103c that drive the piston 102. As shown in FIG.

The configurations of the first friction surface 101a and the second friction surface 101b are as already described. The first friction surface 101a and the second friction surface 101b constitute friction surfaces. Let θ be the inclination angle of the first friction surface 101a and the second friction surface 101b with respect to the axis of the drum 41 and hub 42, and μ be the friction coefficient of the first friction surface 101a and the second friction surface 101b. , the hub 42 can be pulled out from the state in which the drum 41 and the hub 42 are engaged with each other without being caught. Therefore, if the friction coefficient μ is 0.11, the inclination angle must be θ>6.28°.

The piston 102 has a cylindrical shape and is arranged inside the drum 41, as shown in FIG. The end of the piston 102 on the side of the friction surface is connected to the end wall 42d of the second hub 42b via a roller bearing 102a. A shaft portion 102b is provided at the end of the piston 102 opposite to the friction surface side, and the shaft portion 102b is axially movable by spline connection to the shaft portion 41a of the drum 41 and rotatable integrally with the drum 41. are placed. On the outer peripheral surface of the piston 102, a plurality of pressing portions 102c are formed at predetermined intervals in the axial direction by being provided in a stepped shape that widens toward the anti-friction surface side. On the other hand, on the inner peripheral surface of the drum 41 facing the outer peripheral surface of the piston 102, a plurality of coupling portions 41d are formed at predetermined intervals in the axial direction by providing a stepped shape that widens toward the side opposite to the friction surface. there is

The first polymer actuator 103a is composed of a support plate 104, a movable plate 105, and a polymer member 106, as shown in FIG.

The support plate 104 has an annular shape, and as shown in FIG. Electrical insulation is provided between the support plate 104 and the first electrode plate 104a. The outer peripheral edge of the support plate 104 is connected to the connecting portion 41d of the drum 41 by appropriate means. The inner peripheral edge of the support plate 104 has a larger inner diameter than the outer peripheral surface between the roller bearing 102a of the piston 102 and the first pressing portion 102c. The first electrode plate 104a is electrically connected to a first terminal 104b provided on the outer peripheral surface of the support plate 104 via a conductive portion 104c. The first terminal 104 b is connected to a first contact 107 provided on the inner surface of the drum 41 .

The movable plate 105 has an annular shape, and a second electrode plate 105 a is integrally provided on the surface facing the polymer member 106 . Electrical insulation is provided between the movable plate 105 and the second electrode plate 105a. The outer periphery of the movable plate 105 has an outer diameter smaller than the inner surface of the drum 41 between the first coupling portion 41d and the second coupling portion 41d. The inner peripheral edge of the movable plate 105 has an inner diameter smaller than the inner diameter of the support plate 104 so that the first pressing portion 102c of the piston 102 can be pressed. Further, the inner peripheral edge of the movable plate 105 is connected to the first pressing portion 102c by appropriate means so as not to move in the axial direction. The second electrode plate 105b is electrically connected to a second terminal 105b provided on the outer peripheral surface of the movable plate 105 via a conductive portion 105c. The second terminal 105 b is connected to a second contact 110 provided on the inner surface of the piston 102 .

Polymer member 106 has an annular shape, one end face is joined to first electrode plate 104 a of support plate 104 , and the other end face is connected to second electrode plate 105 a of movable plate 105 . The polymer member 106 is formed by laminating an elastomer 106a such as acryl or silicon having a high dielectric constant and elasticity and an intermediate electrode 106b in the axial direction. One of the opposing intermediate electrodes 106 b is connected to the first electrode plate 104 a of the support plate 104 and the other is connected to the second electrode plate 105 a of the movable plate 105 . When a voltage is applied between the first electrode plate 104a and the second electrode plate 105a, the state shown in FIG. is released, it returns to the state of FIG. 4(a) due to its inherent elasticity.

The necessary displacement amount of the polymer member 106 is calculated by (clutch clearance+clutch wear amount)×the number of friction plates. Assuming that the clutch clearance is 0.3 mm, the amount of wear of the clutch is 0.1 mm, and the number of friction plates is 4, the required displacement of the polymer member is 1.2 mm.
The force generated by the polymer member 106 when a voltage is applied can be obtained from the relative permittivity of the material×the permittivity of vacuum×(voltage/thickness) ² , and the amount of displacement is the relative permittivity of the material×the permittivity of vacuum× (Voltage/film thickness) ² /elastic modulus, so that the smaller the film thickness, the greater the generated force and displacement. For this reason, it is preferable that the polymeric material is made by laminating as many thin elastomers as possible so as to obtain the required amount of displacement. Further, by providing a plurality of polymer actuators, the force generated by one polymer actuator can be doubled by the number of polymer actuators.

The second polymer actuator 103b and the third polymer actuator 103c have the same configuration as the first polymer actuator 103a, but as shown in FIG. A plate 105 and a polymer member 106 are used.

The first electrode plate 104a of the support plate 104 of the first, second, and third polymer actuators 103a, 103b, and 103c is provided on the bearing 6a of the transmission case 6 that supports the input shaft 4 via the inside of the drum 41. It is connected to one electrode of a power supply 109 provided outside the transmission case 6 via a connecting part 108 such as a brush. Similarly, the second electrode plate 105a of the movable plate 105 of the first, second, and third polymer actuators 103a, 103b, and 103c moves the inside of the piston 102, the shaft portion 102b of the piston 102, and the shaft portion 41a of the drum 41. It is connected to the other electrode of the power source 109 via a switch 112 that is turned on and off by a control device (not shown) through a connecting part 111 such as a brush provided on the bearing 6a of the transmission case 6.

Alternatively, as shown in FIG. 5, at least three projections 105d are provided on the inner peripheral edge of the movable plate 105 at equal intervals, and the plurality of projections 105d press the first pressing portion 102c of the piston 102. good. Moreover, as shown in FIG. 5, the polymer member 106 may be segmented into a plurality of segments in the circumferential direction.

Next, operation of the first clutch 40 using the frictional engagement device 100A will be described.

Referring to FIG. 2A, when the first clutch 40 is not engaged, the drum 41 and its first friction surface 101a, the piston 102, and the polymer actuators 103a, 103b, 103c rotate together with the input shaft 4, and the hub 42 and its second friction surface 101b are stationary or rotating. When the switch 112 is turned on by a command to engage the first clutch 40, the voltage of the power supply 109 is applied to the first, second and third polymer actuators 103a, 103b and 103c. As a result, as shown in FIG. 2B, the polymer members 106 of the first, second and third polymer actuators 103a, 103b and 103c contract in the axial direction, and the movable member 105 moves to the first position of the piston 102. , the second and third pressing portions 102c. As a result, the piston 102 moves toward the friction surface side and presses the second hub 42b via the roller bearing 102a. The second friction surface 101b presses against the first friction surface 101a of the drum, and the first clutch 40 is engaged. As a result, the hub 42 rotates together with the drum 41 , and the rotational force of the drum 41 is transmitted to the sun gears 11 and 21 of the first and second gear sets 10 and 20 via the hub 42 . Since the roller bearing 102a is interposed between the piston 102 and the second hub 42b, even if the hub 42 rotates at a speed different from that of the drum 41, the piston 102 moves the second hub 42b in the axial direction. can be moved.

When the switch 112 is turned off by the release command of the first clutch 40, the voltage application to the first, second and third polymer actuators 103a, 103b and 103c is canceled and the first, second and third polymer actuators are released. The polymer members 106 of 103a, 103b, and 103c return due to their inherent elasticity, and the movable member 105 pulls back the first, second, and third pressing portions 102c of the piston 102. FIG. As a result, the piston 102 moves toward the side opposite to the friction surface and returns to the state shown in FIG. 2(a). As a result, the first friction surface 101a of the drum 41 and the second friction surface 101b of the hub 42 are no longer pressed, so the first clutch 40 is released, and the hub 42 stops its rotation or returns to its original rotation state. , the rotational force from the drum 41 to the hub 42 is interrupted.

According to the friction fastening device 100A of the above-described embodiment, the polymer actuators 103a, 103b, and 103c move the hub 42 in the axial direction, and the axially inclined first friction surface 101a and the second frictional surface 101a of the drum 41 and the hub 42 move. Since the pressing force is applied to the friction surface composed of the surface 101b, the direction in which the pressing force is generated by the polymer actuators 103a, 103b, and 103c is different from the direction in which the pressing force acting perpendicularly to the friction surface is applied. Thereby, the pressing force acting on the friction surface can be increased by the action of the wedge. When the angle θ between the direction in which the pressing force is generated and the friction surface is 6.28°, the force in the direction in which the pressing force is generated by the polymer actuators 103a, 103b, and 103c is Fact. Then, the boost factor Fcl./Fact.=1 sin .theta.=9.15 times. Therefore, the polymer actuators 103a, 103b, and 103c as pressing force generating means can generate a small pressing force, and the friction coupling device 100A and the automatic transmission using the same can be made lighter and more compact. .

In the friction fastening device 100A of the above-described embodiment, the plurality of polymer actuators 103a, 103b, and 103c arranged in the axial direction press the plurality of pressing portions 102c of the piston 102. Therefore, the displacement is large but the pressing force is small. An increase in the pressing force of the actuator can be ensured. As a result, the frictional engagement device 100A can be made hydraulicless, and drive resistance can be reduced, and the weight and size of the automatic transmission 1 can be reduced.

In addition, each of the plurality of polymer actuators 103a, 103b, and 103c has a support plate 104 whose outer peripheral edge is coupled to one of the plurality of coupling portions 41d of the drum 41, and a movable plate 105 whose inner peripheral edge is coupled to a plurality of pressing portions 102c. , a plurality of polymer actuators 103a, 103b, and 103c can be arranged axially between the drum 41 and the piston 102, which simplifies the structure and facilitates assembly.

Since the plurality of connecting portions 41d of the drum 41 and the plurality of pressing portions 102c of the piston 102 widen toward the side opposite to the frictional surface, the plurality of polymer actuators 103a, 103b, and 103c can be sequentially assembled. becomes easier. Further, the polymer members 106 of the plurality of polymer actuators 103a, 103b, 103c can be increased as they are separated in the anti-friction surface direction, and the pressing force of the piston 102 can be further increased.

The polymer actuators 103a, 103b, and 103c are configured to press the plurality of pressing portions 102c of the piston 102 by a contraction operation due to the application of a voltage to actuate the piston 102, so that a large pressing force is applied to the piston. can be activated and the pressing force of the piston can be further increased.

Although the frictional engagement device 100A of the first embodiment is applied to the first clutch 40 and the second clutch 50, it can also be applied to the first brake 60, the second brake 70 and the third brake 80. When applied to these brakes, the drum 41 does not rotate integrally with the transmission case 6, the hub 42 is the ring gear 14 or the carrier 13 of the first gear set 10, and the piston 102 is axially attached to the transmission case 6. It can be configured in the same manner as the frictional engagement device 100A applied to the first clutch 40 described above, except that it is movably supported in the direction.

In the friction fastening device 100A of the first embodiment, the inclinations of the first friction surface 101a and the second friction surface 101b may be reversed. In this case, the first friction surface 101a is formed on the outer peripheral surface of the tubular portion 41c of the drum 41b, the second friction surface 101b is formed on the inner peripheral surface of the second hub 42b, and the second friction surface 101b of the second hub 42b is formed. is frictionally coupled to the first friction surface 101a of the drum 41 from the outside.

Further, in the frictional fastening device 100A of the first embodiment, the polymer actuators 103a, 103b, and 103c are employed as the pressing force generating means. You may make it drive.

<Second embodiment of friction fastening device>
In the frictional fastening device 100A of the first embodiment, the polymer actuators 103a, 103b, and 103c fixed to the drum 41 press the second hub 42 via the piston 102, and the second friction surface 101b of the second hub 42 is pressed. is frictionally fastened to the first friction surface 101a of the drum 41, but the frictional fastening device 100B of the second embodiment shown in FIG. The second friction surface 101b of the second hub 42b can be frictionally engaged with the first friction surface 101a of the drum 41 by pressing the second hub 42b.

Hereinafter, the frictional fastening device 100B of the second embodiment shown in FIG. 6 will be specifically described. Note that the friction fastening device 100B of the second embodiment has the same configuration as the friction fastening device 100A of the first embodiment, and has the same effects, unless otherwise specified.

The first clutch 40 has a drum 41 and a hub 42 . Unlike the first clutch 40 of FIG. 2, the first clutch 40 of FIG. 6 has a drum 41 arranged on the left side in FIG. 42 is arranged on the right side and is connected to the input shaft 4 .

The drum 41 is formed with a cylindrical portion 41c spaced radially inward from the inner surface of the drum 41 . A first friction surface 101a is formed on the inner surface of the drum 41 and the inner surface of the cylindrical portion 41c. The first friction surface 101a is inclined with respect to the axial direction of the drum 41 so that the diameter increases from the end wall 41b toward the hub.

The hub 42 is composed of a first hub 42a and a second hub 42b. The first hub 42a includes a first tubular portion 42g and a second tubular portion 42h having a smaller diameter than the first tubular portion 42g. The second hub 42b has a tubular shape and is spline-connected to the inner circumference of the first tubular portion 42g of the first hub 42a, and is axially movable with respect to the drum 41 and the first hub 42a. The second hub 42a has a radially extending intermediate wall 42i on its inner peripheral surface. A cylindrical portion 42e is formed on the inner peripheral edge of the intermediate wall 42i at a distance from the inner surface of the second hub 42b. A second friction surface 101b is formed on the outer surface of the second hub 42b and the outer surface of the tubular portion 42e. The second friction surface 101b is inclined at the same angle as the first friction surface 101a with respect to the axial direction of the hub 42 so that the diameter decreases from the intermediate wall 42i toward the drum side. It faces the first friction surface 101a via the provided facing material 42f.

A frictional fastening device 100B is provided between the drum 41 and the hub 42 . The friction fastening device 100B includes a first friction surface 101a of the drum 41, a second friction surface 101b of the second hub 42, a second hub 42b, and first and second friction couplings for driving the second hub 42b. , and third polymer actuators 103a, 103b, and 103c.

A plurality of pressing portions 42j are formed at predetermined intervals in the axial direction on the inner peripheral surface of the second hub 42b by being provided in a stepped shape that widens toward the side opposite to the friction surface. On the other hand, on the outer peripheral surface of the second cylindrical portion 42h of the first hub 42a facing the inner peripheral surface of the second hub 42b, a plurality of coupling portions 42k are provided in a stepped manner widening toward the side opposite to the friction surface. are formed at predetermined intervals in the axial direction.

The first, second, and third polymer actuators 103a, 103b, and 103c have the same configuration as that of the first embodiment, but are arranged to press the second hub 42b instead of the piston. That is, the inner peripheral edge of the support plate 104 is connected to the connecting portion 42k of the second tubular portion 42h of the hub 42 by appropriate means. Further, the outer peripheral edge of the movable plate 105 has an outer diameter larger than the outer diameter of the support plate 104 so as to press the pressing portion 42j of the second hub 42b. Further, the outer peripheral edge of the movable plate 105 is coupled to the pressing portion 42j by appropriate means.

Next, operation of the first clutch 40 using the frictional engagement device 100B will be described.

Referring to FIG. 6A, when the first clutch 40 is not engaged, the first hub 42a of the hub 42, the second hub 42b, the second friction surface 101b of the second hub 42b, the polymer actuators 103a, 103b, 103c rotates together with the input shaft 4, and the drum 41 and its first friction surface 101a are stationary or rotating. When the switch 112 is turned on by a command to engage the first clutch 40, the voltage of the power supply 109 is applied to the first, second and third polymer actuators 103a, 103b and 103c. As a result, as shown in FIG. 6(b), the polymer members 106 of the first, second and third polymer actuators 103a, 103b and 103c contract in the axial direction, and the movable member 105 of the second hub moves toward the second hub. The first, second, and third pressing portions 42j are pressed. As a result, the second hub 42b moves toward the friction surface side, the second friction surface 101b of the second hub 42b presses against the first friction surface 101a of the drum 41, and the first clutch 40 is engaged. As a result, the drum 41 rotates together with the hub 42 , and the rotational force of the hub 42 is transmitted to the sun gears 11 and 21 of the first and second gear sets 10 and 20 via the drum 41 .

When the switch 112 is turned off by the release command of the first clutch 40, the voltage application to the first, second and third polymer actuators 103a, 103b and 103c is canceled and the first, second and third polymer actuators are released. The polymer members 106 of 103a, 103b, and 103c return due to their inherent elasticity, and the movable member 105 pulls back the first, second, and third pressing portions 42j of the second hub 42b. As a result, the second hub 42b moves toward the anti-friction surface side and returns to the state shown in FIG. 6(a). As a result, the first friction surface 101a of the drum 41 and the second friction surface 101b of the hub 42 are no longer pressed, so the first clutch 40 is released, and the drum 41 stops rotating or returns to its original rotating state. , the rotational force from the hub 42 to the drum 41 is interrupted.

Although the second hub 42b is spline-connected to the first cylindrical portion 42g of the first hub 42a in the frictional fastening device 100B of the second embodiment, it may be spline-connected to the second cylindrical portion 42h. Also, the inclinations of the first friction surface 101a and the second friction surface 101b may be reversed. In this case, the first friction surface 101a of the drum 41 is formed on the outer peripheral surface of the drum 41 and the outer peripheral surface of the cylindrical portion 41c, and the second friction surface 101b of the second hub 42b is formed on the inner peripheral surface of the second hub 42b and the cylindrical portion 41c. The second friction surface 101b of the second hub 42b is frictionally coupled to the first friction surface 101a of the drum 41 from the outside.

Furthermore, in the friction fastening device 100B of the second embodiment, the polymer actuators 103a, 103b, and 103c are employed as the pressing force generating means, but instead of the polymer actuators, the second hub 42b is moved by a hydraulically driven piston. You may make it drive.

FIG. 7 shows modifications of the polymer actuators 103a, 103b, and 103c. The support plate 104 and the movable plate 105 of the polymer actuator 103a shown in FIG. 7 are arranged opposite to the polymer actuator 103a shown in FIG. ing. Moreover, unlike the polymer actuator 106 shown in FIG. 4, the polymer member 106 is formed by laminating the elastomer 106a and the intermediate electrode 106b in the radial direction instead of laminating the elastomer 106a and the intermediate electrode 106b in the axial direction. . When a voltage is applied to the first electrode plate 104a and the second electrode plate 105a, the polymer member 106 contracts in the radial direction and expands in the axial direction. The pressing portion 102c of the piston 102 is pressed.

<Third embodiment of friction fastening device>
In the friction fastening device 100A of the first embodiment and the friction fastening device 100B of the second embodiment, the drum 41 and the hub 42 are formed with inclined friction surfaces to generate a pressing force in the axial direction of the hub 42. , the direction in which the pressing force is generated is different from the direction in which the pressing force acting perpendicularly to the friction surface is applied. As shown in FIG. Vertical friction surfaces 101a and 102b are formed, and a polymer actuator 103, which is a pressing force generating means, is provided so that the pressing force generating direction is inclined with respect to the axial direction of the drum 41 and the hub 42. The friction plates 113 of the drum 41 and the hub 42 can be axially pressed via a pressing member 114 having a pressing surface 114b inclined with respect to them.

Hereinafter, the frictional fastening device 100C of the third embodiment shown in FIG. 8 will be specifically described. Although the frictional engagement device 100C of the third embodiment can be applied to both a clutch and a brake, for convenience of explanation, the description will be made without specifying whether it is a clutch or a brake.

The drum 41 has a cylindrical shape and rotates or stops. The hub 42 has a cylindrical shape with a smaller diameter than the drum 41 and is arranged inside the drum 41 concentrically therewith.

A frictional fastening device 100C is provided between the drum 41 and the hub 42 . The friction fastening device 100C is composed of a plurality of friction plates 113a and 113b, a polymer actuator 103 that presses the friction plates 113a and 113b, and a pressing member 114. As shown in FIG.

Of the plurality of friction plates 113a and 113b, the plurality of friction plates 113a disposed inside the drum 41 are spline-connected to the drum 41 so as to be axially movable and rotatable integrally with the drum 41. It is A first friction surface 101a perpendicular to the axial direction of the drum 41 is formed on the friction plate 113a. A plurality of friction plates 113b arranged outside the hub 42 are spline-connected to the hub 42 so as to be axially movable and integrally rotatable with the hub 42 . A second friction surface 101b perpendicular to the axial direction of the hub 42 is formed on the surface of the facing member 113c of the friction plate 113b. The friction plates 113a of the drum 41 and the friction plates 113b of the hub 42 are alternately arranged and face each other via facing members 113c provided on both sides of the friction plates 113b of the hub 42. As shown in FIG.

The polymer actuator 103 has a support plate 104, a movable plate 105, and a polymer member 106, similar to the polymer actuators 103a, 103b, and 103c of the first and second embodiments, except for its overall shape. , and therefore detailed description of the configuration is omitted. The polymer actuator 103 has a rectangular shape as shown in FIG. are arranged at regular intervals.

The polymer actuator 103 is arranged such that the center line in the thickness direction is inclined with respect to the axial direction of the drum 41 and the hub 42 . A support plate 104 for the polymer actuator 103 is bonded to the inner surface of the drum 41 . The first side surface of the polymer actuator 103 obliquely faces the first friction plate 113a, and is allowed to be displaced obliquely with respect to the first friction plate 113a. A second side surface opposite to the first side surface of the polymer actuator 103 is in contact with a regulation plate 115 provided on the drum 41 to regulate deformation in the surface direction. The third and fourth side surfaces perpendicular to the first and second side surfaces of the polymer actuator 103 are freely deformable, but the deformation may be restricted by a restricting plate. One side of the movable plate 105 of the polymer actuator 103 is movable along the regulation plate 115 .

The pressing member 114 has a triangular cross section in the axial direction of the drum 41 and is inclined with respect to the axial direction of the drum 41 and the hub 42 . and a pressing surface 114b perpendicular to the axial direction, in other words, parallel to the first friction plate 113a. The pressing member 114 has its attachment surface 114a attached to the first side surface of the polymer actuator 103, but allows the polymer actuator 103 to deform in the thickness direction and in the surface direction.

When a voltage is applied to electrode plates (not shown) provided on the support plate 104 and the movable plate 105 of the polymer actuator 103, the state shown in FIG. 8(a) is contracted in the thickness direction as shown in FIG. 8(b). When it is stretched in the plane direction and the voltage is released, it returns to the state shown in FIG. 8(a) due to its inherent elasticity. The polymer actuator 103 presses the first friction plate 113a and the second friction plate 113b via the pressing member 114 when the polymer actuator 103 extends in the plane direction.

Next, the operation of the clutch using the frictional engagement device 100C will be described.

Referring to FIG. 8A, when the clutch is not engaged, the drum 41 and its friction plates 113a, the polymer actuator 103, and the pressing member 114 rotate together with the input shaft (not shown), and the hub 42 and its friction plates 113b rotate. Stopped or rotating. When the switch 112 is turned on by a clutch engagement command, the voltage of the power source 109 is applied to the polymer actuator 103 . As a result, as shown in FIG. 8B, the polymer member 106 of the polymer actuator 103 contracts in the axial direction and expands in the planar direction, and the pressing member 114 moves in the axial direction of the drum 41 and the hub 42. obliquely to the drum 41 and toward the center of the hub 42 . As a result, the pressing surface 114b of the pressing member 114 presses the first friction plate 113a of the drum 41 and the second friction plate 113b of the hub 42 while slidingly contacting the first friction plate 113a of the drum 41. are fastened, the hub 42 and its friction plate 113b rotate together with the drum 41 and its friction plate 113a, and the rotational force of the drum 41 is transmitted to the hub 42.

When the switch 112 is turned off by a clutch release command, the voltage applied to the polymer actuator 103 is removed, the polymer member 106 of the polymer actuator 103 returns due to its inherent elasticity, and the pressing member 114 is brought into contact with the drum 41 and the hub. As a result of moving away from the center of the drum 41 and the hub 42 obliquely to the axial direction of the shaft 42, the state shown in FIG. 8(a) is restored. As a result, the first friction plates 113a of the drum 41 and the second friction plates 113b of the hub 42 are no longer pressed, so the clutch 40 is released, and the hub 42 and its friction plates 113b stop rotating or It returns to the rotating state, and the rotational force from the hub 42 to the drum 41 is interrupted.

According to the friction fastening device 100</b>C of the third embodiment, the pressing surface 114 b of the pressing member 114 inclined with respect to the direction in which the pressing force is generated causes the first friction plate 113 a or the second friction plate 113 b to move toward the axis of the drum 41 or hub 42 . direction to apply a pressing force to the friction surfaces 101a and 101b of the first friction plate 113a and the second friction plate 113b perpendicular to the axial direction of the drum 41 or hub 42. The direction in which the force is generated differs from the direction in which the pressing force acting perpendicularly to the friction surfaces 101a and 101b is applied. Thereby, the pressing force acting on the friction surfaces 101a and 102b can be increased by the action of the wedge. When the angle θ between the pressing force generating direction and the pressing surface 114b is 6.28°, the force in the pressing force generating direction by the polymer actuator 103 is Fact. Assuming Fcl., the boost factor Fcl./Fact.=1 sin .theta.=9.15 times. Therefore, the polymer actuator 103 as the pressing force generating means can generate a small pressing force, and the friction coupling device and the automatic transmission using the same can be made lighter and more compact.

According to the frictional fastening device 100C of the third embodiment, the pressing force due to the expansion motion of the polymer member 106 in the plane direction is utilized. The pressing force due to the extension in the plane direction is smaller than the pressing force due to the contraction in the thickness direction, but the direction in which the pressing force is generated due to the extension in the plane direction is the direction in which the pressing force acts perpendicular to the friction surfaces 101a and 101b. , the wedge action can increase the pressing force acting on the friction surfaces 101a and 101b.

According to the friction fastening device 100C of the third embodiment, the pressing surface 114b of the pressing member 114 is parallel to the first friction plate 113a and the second friction plate 113b and directly presses the first friction plate 113a. becomes easier.

<Fourth Embodiment of Friction Fastening Device>
In the friction fastening device 100C of the third embodiment, the polymer actuator 103 is arranged obliquely with respect to the axial direction of the drum 41 and the hub 42. However, as shown in FIG. It can also be arranged perpendicular to the axis of 42 .

Hereinafter, the frictional fastening device 100D of the fourth embodiment shown in FIG. 10 will be specifically described. Note that the friction fastening device 100D of the fourth embodiment has the same configuration as the friction fastening device 100C of the third embodiment, and has the same effects, unless otherwise specified.

Of the plurality of first friction plates 113 a of the drum 41 , the surface of the first friction plate 113 a adjacent to the polymer actuator 103 on the polymer actuator side has a pressure receiving portion 116 inclined with respect to the axial direction of the drum 41 . is projected. The pressing force receiving portion 116 is inclined so as to move away from the friction surface side as it goes radially inward.

The polymer actuator 103 is arranged so that the center line in the thickness direction is parallel to the axial direction of the drum 41 and the hub 42 .

The pressing member 114 has an L-shaped cross section in the axial direction of the drum 41 and is parallel to the axial direction of the drum 41 and the hub 42 . It has a pressing surface 114 b that is inclined with respect to the direction, faces the pressing force receiving portion 116 , and is parallel to the pressing force receiving portion 116 .

Next, the operation of the clutch using the frictional engagement device 100D will be described.

Referring to FIG. 10(a), when the clutch is not engaged, the drum 41 and its friction plates 113a, the polymer actuator 103, and the pressing member 114 rotate together with the input shaft (not shown), and the hub 42 and its friction plates 113b rotate. Stopped or rotating. When the switch 112 is turned on by a clutch engagement command, the voltage of the power supply 109 is applied to the polymer actuator 103 . As a result, as shown in FIG. 10B, the polymer member 106 of the polymer actuator 103 contracts in the thickness direction and expands in the surface direction, and the pressing member 114 moves in the axial direction of the drum 41 and the hub 42. , toward the center of drum 41 and hub 42 . As a result, while the pressing surface 114b of the pressing member 114 is in sliding contact with the pressing force receiving portion 116 of the first friction plate 113a of the drum 41, the first friction plate 113a of the drum 41 and the second friction plate 113b of the hub 42 are pressed together. Since the pressure is applied, the clutch 40 is engaged, the hub 42 and its friction plates 113b rotate together with the drum 41 and its friction plates 113a, and the rotational force of the drum 41 is transmitted to the hub 42.

When the switch 112 is turned off by a clutch release command, the voltage applied to the polymer actuator 103 is removed, the polymer member 106 of the polymer actuator 103 returns due to its inherent elasticity, and the pressing member 114 is brought into contact with the drum 41 and the hub. As a result of moving away from the center of drum 41 and hub 42 perpendicular to the axial direction of 42, the state of FIG. 10(a) is restored. As a result, the first friction plate 112a of the drum 41 and the second friction plate 113b of the hub 42 are no longer pressed, so the clutch 40 is released, and the hub 42 and its friction plate 113b stop rotating or It returns to the rotating state, and the rotational force from the drum 41 to the hub 42 is interrupted.

According to the friction fastening device 100D of the fourth embodiment, the pressing surface 114b of the pressing member 114 is parallel to the pressing force receiving portion 116 of the first friction plate 113a inclined with respect to the axial direction of the drum 41. The polymer actuator 103 can be arranged in parallel with the first friction plate 113a and the second friction plate 113b, and the arrangement of the polymer actuator 103 is facilitated.

The present invention is not limited to the above embodiments, and can be modified in various ways. For example, when applied to a brake, the ring gear of the gear set is used as the hub in the first and second embodiments, but the pinion carrier may be used as the hub. In the first and second embodiments, the shape of the polymer member of the polymer actuator is ring-shaped or segment-shaped. may be placed in

INDUSTRIAL APPLICABILITY As described above, the frictional engagement device according to the present invention may be suitably used for clutches and brakes of transmissions of automobiles.

1 automatic transmission 41 drum 41b coupling portion
42 hub 42a first hub 42b second hub 42j pressing portion 42k coupling portions 100A to 100D friction fastening device
101a First friction surface 10bb Second friction surface 102 Piston (pressing member)
102c pressing portions 103, 103a, 103b, 103c polymer actuator 104 support plate 105 movable plate 106 polymer member 113a first friction plate 113b second friction plate 114 pressing member 114b pressing surface 116 pressing force receiving portion

Claims (9)

A friction fastening device comprising friction surfaces facing each other provided on a drum and a hub, and pressing force generating means for generating a pressing force acting on the friction surfaces,
The friction surface is
a first friction surface provided on the drum and inclined with respect to the axial direction of the drum;
a second friction surface provided on the hub, inclined with respect to the axial direction of the hub, and opposed to the first friction surface;
wherein the hub is axially movably provided with respect to the drum;
The pressing force generating means is configured to generate a pressing force against the hub in the axial direction of the hub to move the hub in the axial direction,
A pressing member is provided for axially pressing the hub,
The pressing force generating means is composed of a polymer actuator composed of two electrode plates and a polymer member interposed between the two electrode plates, and the outer peripheral edge of one electrode plate is formed on the drum. A frictional fastening device coupled to a coupling portion, wherein the inner peripheral edge of the electrode plate on the other side is coupled to a pressing portion formed on the pressing member. A friction fastening device comprising friction surfaces facing each other provided on a drum and a hub, and pressing force generating means for generating a pressing force acting on the friction surfaces,
The friction surface is
a first friction surface provided on the drum and inclined with respect to the axial direction of the drum;
a second friction surface provided on the hub, inclined with respect to the axial direction of the hub, and opposed to the first friction surface;
wherein the hub is axially movably provided with respect to the drum;
The pressing force generating means is configured to generate a pressing force against the hub in the axial direction of the hub to move the hub in the axial direction,
the hub is spline-engaged with a first hub having a first tubular portion and a second tubular portion having a diameter smaller than that of the first tubular portion, and the first tubular portion or the second tubular portion of the first hub; a second hub having the second friction surface;
The pressing force generating means is composed of a polymer actuator including two electrode plates and a polymer member interposed between the two electrode plates, and one electrode plate is formed on the second hub. and the electrode plate on the other side is connected to a connecting portion formed in the first cylindrical portion and the second cylindrical portion of the first hub to which the second hub is not spline-connected. Fastening device. 3. The frictional fastening device according to claim 1, wherein a plurality of said polymer actuators are provided in the axial direction. 4. The method according to claim 3, wherein at least one of the plurality of pressing portions and the plurality of coupling portions to which the two electrode plates of the polymer actuator are coupled is formed in a stepped shape widening toward the anti-friction plate side. friction fastening device. 5. The frictional fastening device according to claim 3, wherein the plurality of pressing portions are pressed by a contraction operation caused by applying a voltage to the polymer actuator. A friction fastening device comprising friction surfaces facing each other provided on a drum and a hub, and pressing force generating means for generating a pressing force acting on the friction surfaces,
The friction surface is
a first friction surface provided on a first friction plate provided on the drum and perpendicular to the axial direction of the drum;
a second friction surface provided on a second friction plate provided on the hub, perpendicular to the axial direction of the hub and opposed to the first friction surface;
The pressing force generating means has a pressing member provided with a pressing surface inclined with respect to the pressing force generating direction,
A friction fastening device configured to press the first friction plate or the second friction plate in the axial direction of the drum or the hub by a pressing surface of the pressing member. The pressing force generating means is composed of a polymer actuator comprising two electrode plates and a polymer member interposed between the two electrode plates,
7. The frictional fastening device according to claim 6, wherein the pressure member is displaced by an extension operation in the surface direction of the polymer member when the polymer actuator is contracted by applying a voltage. The polymer actuator has one of the two electrode plates fixed to the drum so that the pressing surface of the pressing member is parallel to the first friction plate and the second friction plate. 8. The friction fastening device according to 7. The first friction plate is provided with a pressing force receiving portion inclined with respect to the axial direction of the drum, which is in sliding contact with the pressing surface of the pressing member of the polymer actuator,
In the polymer actuator, either one of the two electrode plates is fixed to the drum so that the pressing surface of the pressing member is parallel to the pressing force receiving portion of the first friction plate. 8. The friction fastening device according to 7.

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