JP7206627B2 - 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 of automatic transmissions of automobiles are driven by hydraulic pressure from a hydraulic pump, so that driving resistance is large and the weight of the automatic transmission is increased, resulting in an increase in size. In order to reduce the driving resistance of the friction coupling device and to reduce the weight and size of the automatic transmission, it is effective to eliminate hydraulic pressure by using an electric actuator.

Conventionally, Patent Document 1 discloses a clutch using a polymer actuator in which an actuator element formed by bundling and spirally winding conductive polymer tubes is housed in a space defined by a cylindrical cylinder and a cylindrical piston. A device 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

The present invention has been devised in view of the above-mentioned conventional problems. It is possible to secure an increase in the pressing force of a polymer actuator, which has a large displacement but a small pressing force, to reduce the driving resistance, and to reduce the weight and size of the actuator. An object of the present invention is to provide a friction fastening device capable of

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

According to the first aspect of the invention, there is provided a pressing member provided between a drum and a hub, and having a plurality of friction plates that alternately engage the drum and the hub, and a pressing portion that presses the plurality of friction plates to fasten them together. A friction fastening device comprising a member,
A polymer actuator is provided between the drum and the pressing member for applying an axial pressing force to the pressing member,
a power transmission unit configured to transmit power between the drum and the hub by radial expansion caused by axial contraction of the polymer actuator;
Power transmission in the power transmission unit due to pressing of the plurality of friction plates by the pressing member accompanying axial contraction of the polymer actuator and radial expansion occurring accompanying axial contraction of the polymer actuator. Perform a two-step fastening operation with

In the invention of claim 2 , the polymer actuator comprises two electrode plates and a polymer member interposed between the two electrode plates, one electrode plate being coupled to the drum, and the other electrode plate being coupled to the drum. An electrode plate is coupled to the pressing member .

In the third aspect of the present invention, the power transmission portion includes a base portion that is in contact with the radially outer surface of the polymer actuator, and a base portion that faces the inner surface of the hub and is engaged with the inner surface of the hub by radially expanding the polymer actuator. and an engaging portion.

In the fourth aspect of the invention, the engaging portion of the power transmission portion is made of a friction member having a lower coefficient of friction than that of the friction plate, and is configured to transmit power prior to pressing by the pressing member . .

According to the fifth aspect of the invention, the engaging portion of the power transmission portion is formed of unevenness that engages with the hub, and is configured such that power is transmitted after pressing by the pressing member .

According to the first aspect of the present invention, since a two-step fastening operation of pressing the friction plate by the pressing portion of the pressing member and transmitting power to the hub by the power transmission portion is performed, the amount of fastening torque increases. , it is possible to ensure an increase in the pressing force of polymer actuators, which have 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, since the axial pressing force due to the axial contraction of the polymer member can be directly applied to the pressing member via the electrode plate, the pressing member can be compact and simple in structure. become.

According to the third aspect of the invention, the power transmission portion faces the base portion that contacts the radially outer surface of the polymer actuator and the inner surface of the hub, and engages with the inner surface of the hub due to radial expansion of the polymer actuator. Since the engaging portion is provided, the pressing force due to radial expansion of the polymer actuator can be reliably transmitted to the hub.

According to the fourth aspect of the invention, the power transmission portion having a low coefficient of friction causes a smooth slip between the power transmission portion and the drum, and then the friction plate between the drum and the hub is fastened by the pressing portion of the pressing member . can be made, and reliable power transmission can be performed.

According to the invention of claim 5, since the friction plate between the drum and the hub is fastened by the pressing portion of the pressing member , and then the drum and the hub are engaged by the unevenness , power transmission can be performed reliably.

1 is a schematic diagram of an automatic transmission to which a frictional engagement device of the present invention is applied; FIG. FIG. 4 is a cross-sectional view showing the non-engagement (a), the first half (b) of the engagement, and the latter half (c) of the engagement of the friction fastening device of the first embodiment. FIG. 4 is an enlarged cross-sectional view showing (a) before voltage application and (b) after voltage application of the polymer actuator. FIG. 10 is a diagram showing a modification of the polymer member of the polymer actuator; Sectional drawing which shows VV line sectional drawing (a) of Fig.2 (a), and its modification (b). Sectional drawing which shows the state of the friction fastening device of 2nd Embodiment at the time of non-engagement (a), the first half (b) of engagement, and the latter half (c) of engagement. VII-VII line sectional view of FIG. 6(a).

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, FIG. 2 shows an embodiment of a frictional engagement device 100A applied to the first clutch 40, the second clutch 50, the first brake 60, the second brake 70, and the third brake 80 of the automatic transmission 1. to explain. The frictional engagement device 100A can be applied to both clutches and brakes, but for convenience of explanation, the case where it is applied to the first clutch 40 will be described.

The first clutch 40 has a drum 41 and a hub 42 . The first clutch 40 has a drum 41 arranged on the left side in FIG. It is

The drum 41 has a cylindrical shape and rotates or stops. The drum 41 has an end wall 41a at one end and a plurality of axially long notches 41b formed at the other end into which connecting portions 113c of the polymer actuator 103, which will be described later, are fitted. A support wall 41c is formed on the inner peripheral surface of the drum 41 to support a ring-shaped polymer actuator 130, which will be described later, extending radially inward.

The hub 42 has a cylindrical shape with a smaller diameter than the drum 41 and is arranged inside the drum 41 concentrically therewith. An end wall 42a is provided at one end of the hub 42 opposite the drum, and the end wall 42a is further extended radially outward to form a cylindrical portion 42b on the outer peripheral edge. The cylindrical portion 42b has a larger diameter than the drum 41 and is formed to cover the end of the drum 41 where the notch 41b is formed.

A frictional fastening device 100A is provided between the drum 41 and the hub 42 . The friction fastening device 100A includes a plurality of friction plates 101a and 101b, a pressing member 102 (hereinafter referred to as "piston") that presses the friction plates 101a and 101b, a polymer actuator 103 that drives the piston 102, It is composed of a plurality of power transmission units 113 .

Of the plurality of friction plates 101a and 101b, the plurality of friction plates 101a 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 plurality of friction plates 101b arranged outside the hub 42 are spline-connected to the hub 42 so as to be axially movable and rotatable together with the hub 42 . The friction plates 101a of the drum 41 and the friction plates 101b of the hub 42 are alternately arranged and face each other via facing members 101c provided on both sides of the friction plates 101b of the hub 42. As shown in FIG.

The piston 102 has a cylindrical shape and is arranged between the support wall 41 c of the drum 41 and the outer surface of the hub 42 . The end of the piston 102 on the friction plate side serves as a pressing portion 102a for pressing the friction plates 101a and 101b. The end of the piston 102 on the side opposite to the friction plate is coupled to the movable plate 105 of the polymer actuator 130, which will be described later. Piston 102 is preferably splined to the inner circumference of support wall 41 c of drum 41 .

The first polymer actuator 103 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 surface of the support plate 104 opposite to the polymeric member is coupled to the support wall 41c of the drum 41. As shown in FIG. The first electrode plate 104a is electrically connected to the first terminal 104b. The first terminal 104b is connected to a first contact 107 provided on the supporting wall 41c of the drum 41. As shown in FIG.

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 peripheral edge of the movable plate 105 has the same diameter as the outer peripheral edge of the support plate 104 . The inner peripheral edge of the movable plate 105 has an inner diameter smaller than the inner diameter of the support plate 104 and is fitted to the end face of the piston 102 . The second electrode plate 105a is electrically connected to the second terminal 105b. The second terminal 105b is connected via the piston 102 to a second contact 110 provided on the support wall 41c of the drum 41. As shown in FIG.

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. 3(a) is contracted in the thickness direction as shown in FIG. When the voltage 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 necessary displacement amount of polymer member 106 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 polymer member 106 is made by laminating as many elastomers as thin as possible so as to obtain the necessary amount of displacement. Also, by providing a plurality of polymer actuators 103 , the force generated by one polymer actuator 103 can be doubled by the number of polymer actuators 103 .

A first electrode plate 104a of the support plate 104 of the polymer actuator 103 is connected to one electrode of an externally provided power source 109 via a bearing portion of the drum 41. As shown in FIG. Similarly, the second electrode plate 105a of the movable plate 105 of the polymer actuator 103a is connected to the other electrode of the power source 109 via the piston 102 and the drum bearings (not shown), and a switch 112 that is turned on and off by a control device (not shown). connected through

The polymer member 106 may be segmented into a plurality of pieces in the circumferential direction as shown in FIG. 4(a), or may be a plurality of circular pieces as shown in FIG. 4(b).

The plurality of power transmission portions 113 each include a base portion 113a positioned on the polymer member 106 side of the polymer actuator 103, an engaging portion 113b positioned on the cylindrical portion 42b side of the hub 41, and the base portion 113b and the engaging portion. It is composed of a connecting portion 113c to be connected.

The base portion 113a has a ring shape that circumscribes the polymeric member 106 of the polymeric actuator 103, as shown in FIG. The base portion 113a can be elastically deformed radially outward by stretching the polymer member 106 in the plane direction. As shown in FIG. 5B, the base portion 113 is not ring-shaped, but has a segment shape divided in the circumferential direction. The in-plane or radial pressing force of 106 can be applied directly to the hub 42 .

The engaging portion 113b has an arcuate engaging surface 113d along the inner surface of the cylindrical portion 42b of the hub 42 . The engaging surface 113d has a coefficient of friction μ2 (μ2<μ1) smaller than the coefficient of friction μ1 between the first friction plate 101a and the second friction plate 101b.

The connecting portion 113c has a shape of a plurality of pins that connect the outer surface of the base portion 113a and the inner surface of the engaging portion 113b. The connecting portion 113c is engaged with the notch 41b of the drum 41 so that the base portion 113a at one end is positioned inside the drum 41 and the engaging portion 113b at the other end is positioned outside the drum 41 .

As shown in FIG. 5, the plurality of power transmission portions 113 are arranged at four positions in the circumferential direction at regular intervals. The number of power transmission units 113 is not limited to four as long as it is three or more.

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 friction plates 101a, the piston 102, and the polymer actuator 103 rotate together with the input shaft (not shown), and the hub 42 and its friction plates rotate. 101b is stopped or rotating. When the switch 112 is turned on by a command to engage the first clutch 40 , the voltage of the power source 109 is applied to the polymer actuator 103 . As a result, as shown in FIGS. 2B and 2C, the polymer member 106 of the polymer actuator 103 contracts in the axial direction (thickness direction) and expands in the radial direction (surface direction). Displace. The friction fastening device 113 performs a two-step fastening operation in the first half and the second half of displacement of the polymer actuator 103 .

In the first half of displacement of the polymer actuator 103, the engaging portion 113b of the power transmission portion 113 presses the inner surface of the cylindrical portion 42b of the hub 42, as shown in FIG. 2(b). Since the engaging surface 113d of the engaging portion 113b has a small coefficient of friction μ2, the engaging surface 113d starts slipping smoothly on the inner surface of the cylindrical portion 42b of the hub . Power is transmitted gently from the drum 41 to the hub 42 .

In the latter half of the displacement of polymer actuator 103, polymer member 106 contracts in the axial direction, and movable member 105 presses piston 102, as shown in FIG. As a result, the piston 102 moves toward the friction plate side, and the pressing portion 102a of the piston 102 presses the friction plate 101a of the drum 41 and the friction plate 101b of the hub 42, so that the first clutch 40 is engaged and the hub 42 and its friction plate 101b rotate together with the drum 41 and its friction plate 101a, and the rotational force of the drum 41 is transmitted to the sun gears 11, 21 of the first and second gear sets 10, 20 through the hub 42.

When the switch 112 is turned off by the release command of the first clutch 40, the voltage application to the polymer actuator 103 is canceled and the polymer member 106 of the polymer actuator 103 returns due to its inherent elasticity. As a result, the movable member 105 pulls back the piston 102, the piston 102 moves toward the anti-friction plate side, and the friction plate 101a of the drum 41 and the friction plate 101b of the hub 42 are no longer pressed. On the other hand, the power transmission portion 113 retreats radially inward, and the engagement portion 113b of the power transmission portion 113 separates from the cylindrical portion 42b of the drum 41 . As a result, the first clutch 40 is released, the hub 42 and its friction plate 101b stop rotating, and the rotational force from the drum 41 to the hub 42 is cut off.

In the friction fastening device 100A of the above embodiment, in addition to pressing the friction plates 101a and 101b by the pressing portion 102a of the piston 102, power is transmitted to the hub 42 by the power transmission portion 113, so the amount of fastening torque is increased. , it is possible to ensure an increase in the pressing force of polymer actuators, which have a large displacement but a small pressing force. 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, since the frictional fastening device 100A can apply the axial pressing force due to the axial displacement of the polymer member 106 directly to the piston 102 via the movable plate 105 having the electrode plate 104a, the piston 102 is compact. and the structure becomes simple.

In the frictional fastening device 100A, the power transmission portion 113 faces the inner surface of the hub 42 and the base portion 113a in contact with the radial outer surface of the polymer actuator 103, and the radial displacement of the polymer actuator 103 causes the power transmission portion 113 to move to the inner surface of the hub 42. Since the engaging portion 113 b is provided, the pressing force due to the radial displacement of the polymer actuator 103 can be reliably transmitted to the hub 42 .

Further, the frictional fastening device 100A causes the power transmission portion 113 with a low coefficient of friction to start slipping smoothly between the power transmission portion 113 and the drum 42, and then the pressure portion 102a of the piston 102 causes the friction between the drum 41 and the hub 42 to slip. friction plates 101a and 101b can be fastened, and reliable power transmission can be performed.

<Second embodiment of friction fastening device>
In the friction fastening device 100A of the first embodiment, the power transmission portion 113 is provided with the engagement portion 113b having a low coefficient of friction. can do.

Hereinafter, a frictional engagement device 100B of the second embodiment having a power transmission portion 113 using a dog clutch shown in FIG. 6 will be specifically described. The frictional fastening device 100B of the second embodiment is the same as the frictional fastening device 100A of the first embodiment except that the engagement structure between the inner surface of the cylindrical portion 42b of the hub 42 and the engaging portion 113b of the power transmission portion 113 is different. , and the same functions and effects are obtained.

On the inner surface of the cylindrical portion 42b of the hub 42, as shown in FIG. 7, unevenness 113e is formed on the entire inner peripheral surface. On the other hand, an engaging surface 113d of the engaging portion 113b of the power transmission portion 113 is formed with unevenness 113f that meshes with the unevenness 113e of the inner surface of the cylindrical portion 42b of the hub 42 . Thus, the cylindrical portion 42b of the hub 42 and the engagement portion 113b of the power transmission portion 113 constitute a dog clutch mechanism. Engagement by the dog clutch mechanism between the cylindrical portion 42b of the hub 42 and the engaging portion 113b of the power transmission portion 113 is performed after pressing by the piston 102, that is, when the drum 42 and the first friction plate 101a and the second friction plate of the hub 42 are engaged. 101b is configured to be performed after frictional engagement.

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 drum 41 and its friction plates 101a, the piston 102, and the polymer actuator 103 rotate together with the input shaft (not shown), and the hub 42 and its friction plates rotate. 101b is stopped or rotating. When the switch 112 is turned on by a command to engage the first clutch 40 , the voltage of the power source 109 is applied to the polymer actuator 103 . As a result, as shown in FIGS. 6B and 6C, the polymer member 106 of the polymer actuator 103 contracts in the axial direction (thickness direction) and expands in the radial direction (surface direction). Displace. The friction fastening device 113 performs a two-step fastening operation in the first half and the second half of displacement of the polymer actuator 103 .

In the first half of displacement of the polymer actuator 103, as shown in FIG. 6B, the movable member 105 presses the piston 102 due to contraction of the polymer member 106 in the axial direction. As a result, the piston 102 moves toward the friction plate side, and the pressing portion 102a of the piston 102 presses the friction plate 101a of the drum 41 and the friction plate 101b of the hub 42, so that the first clutch 40 is engaged and the hub 42 and its friction plate 101b rotate together with the drum 41 and its friction plate 101a, and the rotational force of the drum 41 is transmitted to the sun gears 11, 21 of the first and second gear sets 10, 20 through the hub 42.

In the latter half of the displacement of the polymer actuator 103, as shown in FIG. Thus, the drum 41 and the hub 42 are securely fastened.

When the switch 112 is turned off by the release command of the first clutch 40, the voltage application to the polymer actuator 103 is canceled and the polymer member 106 of the polymer actuator 103 returns due to its inherent elasticity. As a result, first, the engagement between the engaging portion 113b of the power transmission portion 113 and the cylindrical portion 42b of the drum 42 is released. Next, the movable member 105 pulls back the piston 102, the piston 102 moves toward the anti-friction plate side, and the friction plate 101a of the drum 41 and the friction plate 101b of the hub 42 are no longer pressed. 6A, the first clutch 40 is released, the hub 42 and its friction plate 101b stop rotating, and the rotational force from the drum 41 to the hub 42 is cut off.

In the friction fastening device 100B, the friction plates 101a and 101b between the drum 41 and the hub 42 are fastened by the pressing portion 102a of the piston 102, and then the drum 41 and the hub 42 are engaged by the dog clutch. be able to.

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 above embodiment, but the pinion carrier may be used as the hub.

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 42 hub 42b cylindrical portions 100A, 100B friction engagement devices 101a, 101b friction plate 102 piston (pressing member)
102a Pressing portion 103 Polymer actuator 104 Support plate 105 Movable plate 106 Polymer member 113 Power transmission portion 113a Base portion 113b Engagement portion 113c Connection portion 113d Engagement surface 113e Dog clutch (unevenness)
113f dog clutch (unevenness)

Claims (5)

Friction fastening comprising a plurality of friction plates provided between a drum and a hub and alternately engaged with the drum and the hub, and a pressing member having a pressing portion pressing the plurality of friction plates to fasten them together a device,
A polymer actuator is provided between the drum and the pressing member for applying an axial pressing force to the pressing member,
a power transmission unit configured to transmit power between the drum and the hub by radial expansion caused by axial contraction of the polymer actuator;
Power transmission in the power transmission unit due to pressing of the plurality of friction plates by the pressing member accompanying axial contraction of the polymer actuator and radial expansion occurring accompanying axial contraction of the polymer actuator. A friction fastening device that performs a two-step fastening operation with . The polymer actuator comprises two electrode plates and a polymer member interposed between the two electrode plates. One electrode plate is coupled to the drum, and the other electrode plate is attached to the pressing member. 2. The friction fastening device of claim 1, wherein the friction fastening device is coupled. The power transmission portion includes a base portion that contacts the radially outer surface of the polymer actuator, and an engaging portion that faces the inner surface of the hub and engages the inner surface of the hub due to radial expansion of the polymer actuator. The friction fastening device according to claim 1 or 2. 4. The friction according to claim 3, wherein the engaging portion of the power transmission portion is made of a friction member having a lower coefficient of friction than that of the friction plate, and is configured such that power is transmitted prior to pressing by the pressing member. Fastening device. 4. The frictional fastening device according to claim 3, wherein the engaging portion of the power transmission portion is formed of projections and depressions that engage with the hub, and is configured such that power is transmitted after pressing by the pressing member.

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