JP2019190640A - Friction fastening device - Google Patents

Abstract

To provide a friction fastening device capable of securing increase in pressing force of a polymer actuator whose displacement is made large but pressing force is made small, reducing drive resistance, and attaining both weight saving and compactification.SOLUTION: A friction fastening device comprises a plurality of friction plates 101a, 101b provided between a drum 41 and a hub 42 and alternately engaging with the drum and the hub, and a piston 102 having a pressing unit 102a that presses the plurality of friction plates to fasten them together. Between the drum and the piston, a polymer actuator 103 is provided for imparting axial pressing force to the piston. A power transmission unit 113 is provided for transmitting power to the hub by a radial displacement caused by an axial displacement of the polymer actuator.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a friction fastening device applied to a clutch and a brake in an automatic transmission of an automobile.

  Conventionally, friction fastening devices such as clutches and brakes of an automatic transmission of an automobile are driven by hydraulic pressure from a hydraulic pump, so that the driving resistance is large and the weight of the automatic transmission is increased and the size is increased. In order to reduce the driving resistance of the friction fastening device and to reduce the weight and size of the automatic transmission, it is effective to use an electric actuator without hydraulic pressure.

  Conventionally, Patent Document 1 discloses a clutch using a polymer actuator in which an actuator element in which a conductive polymer tube is bundled and spirally wound 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, and the number of parts increases and the structure is complicated.

  Patent Documents 2 and 3 propose a clutch device using a polymer actuator in which an elastic container in which a gel-like electric field-responsive volume phase transition polymer and an electrolyte are sealed is housed between a cylinder and a piston. . However, this has a problem that it lacks durability because a gel-like polymer and an electrolyte are enclosed in an elastic container.

  Due to these conventional problems, the use of an electric actuator for a friction fastening device has not been put into practical use. The electrical actuator includes a piezoelectric type (piezoelectric ceramic) and a dielectric type (polymer actuator). The piezoelectric type has a large pressing force but a small displacement, and the dielectric type has a drawback that the displacement is large but the pressing force is small. For this reason, in order to apply to a friction fastening device such as a clutch or a brake, a mechanism for enlarging displacement is required for the piezoelectric actuator, and a booster mechanism is required for the dielectric actuator.

JP 2005-83466 A Japanese Patent Laying-Open No. 2005-155871 JP 2011-106564 A

  The present invention has been made in view of the above-mentioned conventional problems, and it is possible to secure an increase in the pressing force of a polymer actuator having a large displacement but a small pressing force, thereby reducing driving resistance, reducing the weight and reducing the size. It is an object to provide a friction fastening device that can be used.

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

The invention according to claim 1 is a piston having a plurality of friction plates which are provided between the drum and the hub and alternately engage with the drums and the hub, and a pressing portion which presses the plurality of friction plates and fastens them together. A friction fastening device comprising:
A polymer actuator is provided between the drum and the piston to apply an axial pressing force to the piston,
A power transmission unit is provided that transmits power to the hub by a radial displacement caused by an axial displacement of the polymer actuator.

  In the invention of claim 1, the polymer actuator is composed of two electrode plates and a polymer member interposed between the two electrode plates, and one electrode plate is coupled to the drum, An electrode plate is coupled to the piston.

  According to a third aspect of the present invention, the power transmission portion is opposed to the base portion in contact with the outer surface in the radial direction of the polymer actuator and the inner surface of the hub, and is engaged with the inner surface of the hub by the radial displacement of the polymer actuator. Engaging portion.

  According to a fourth aspect of the present invention, the power transmission unit is made of a friction member having a lower coefficient of friction than the friction plate, and is configured to transmit power before being pressed by the piston.

  According to a fifth aspect of the present invention, the power transmission unit is a dog clutch that engages with the hub, and is configured to transmit power after being pressed by the piston.

  According to the first aspect of the present invention, in addition to the pressing of the friction plate by the pressing portion of the piston, the power transmission is performed to the hub by the power transmission portion, so that the fastening torque amount is increased and the displacement is large but the pressing force is large. An increase in the pressing force of the small polymer actuator can be ensured. As a result, the friction fastening device can be hydraulic-less, and drive resistance can be reduced, and the weight and size can be reduced.

  According to the invention of claim 2, since the axial pressing force due to the axial displacement of the polymer member can be directly applied to the piston through the electrode plate, the piston becomes compact and the structure becomes simple. .

  According to the invention of claim 3, the power transmission portion is opposed to the base portion in contact with the radial outer surface of the polymer actuator and the inner surface of the hub, and engages with the inner surface of the hub by the radial displacement of the polymer actuator. Since the engaging portion is provided, the pressing force due to the radial displacement of the polymer actuator can be reliably transmitted to the hub.

  According to the invention of claim 4, slip is smoothly started between the power transmission unit and the drum by the power transmission unit having a low friction coefficient, and then the friction plate between the drum and the hub is fastened by the pressing unit of the piston. And reliable power transmission can be performed.

  According to the fifth aspect of the present invention, the friction plate between the drum and the hub is fastened by the pressing portion of the piston, and then the drum and the hub are engaged by the dog clutch, so that reliable power transmission can be performed.

1 is a schematic view of an automatic transmission to which a friction fastening device of the present invention is applied. Sectional drawing which shows the state at the time of non-fastening (a), the time of fastening first half (b), and the time of fastening second half (c) of the friction fastening device of 1st Embodiment. The expanded sectional view which shows before voltage application (a) and after voltage application (b) of a polymer actuator. The figure which shows the modification of the polymer member of a polymer actuator. Sectional drawing which shows the VV sectional view (a) of FIG. 2 (a), and its modification (b). Sectional drawing which shows the state of the time of non-fastening (a) and the time of fastening first half (b), and the time of fastening second half (c) of the friction fastening device of 2nd Embodiment. VII-VII sectional view taken on the line of Fig.6 (a).

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

<Configuration of automatic transmission>
First, the configuration of an example automatic transmission in which the friction fastening device of the present invention is used will be described with reference to FIG. The automatic transmission 1 is applied to an engine horizontally mounted vehicle such as a front engine front drive vehicle and the like. As main components, a torque converter 3 attached to an engine output shaft 2 and an output of the torque converter 3 are provided. And a transmission mechanism 5 in which the rotation is input via the input shaft 4. The transmission mechanism 5 is housed in the transmission case 6 in a state where the transmission mechanism 5 is disposed on the axis of the input shaft 4.

  Then, the output rotation of the transmission mechanism 5 is transmitted to the differential device 9 via the counter drive mechanism 8 from the output gear 7 which is also disposed in the intermediate portion of the input shaft 4 on the axis of the input shaft 4. The 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 opposed to the pump 3b and driven by the pump 3b via hydraulic oil. A turbine 3c, 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, and the case 3a and the turbine 3c, and a lock-up clutch 3f that directly connects the engine output shaft 2 and the turbine 3c via the case 3a. Then, the rotation of the turbine 3 c is transmitted to the transmission mechanism 5 through the input shaft 4.

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

  Further, as a friction element constituting the speed change mechanism 5, a first clutch 40 and a second clutch 50 are disposed on the torque converter side of the output gear 7, and a first clutch 40 and a second clutch 50 are disposed on the counter torque converter side of the output gear 7. 1 brake 60, 2nd brake 70, and 3rd brake 80 are arrange | positioned in order from the torque converter side, and the one-way clutch 90 is arrange | positioned in parallel with the 1st brake 60 further.

  Each of the first, second, and third gear sets 10, 20, and 30 is a single pinion type planetary gear set, and is engaged with the sun gears 11, 21, and 31 and the sun gears 11, 21, and 31, respectively. A plurality of pinions 12, 22, 32, carriers 13, 23, 33 that respectively support these pinions 12, 22, 32, and ring gears 14, 24, 34 that mesh 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, 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 connected to each other. The output gear 7 is connected to the carrier 13 of the first gear set 10.

  Further, 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 through the first clutch 40 so as to be connectable and detachable, and the carrier 23 of the second gear set 20 is The input shaft 4 is connected to the input shaft 4 via the second clutch 50 so as to be connected and disconnected.

  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 via the first brake 60 and the one-way clutch 90 arranged in parallel so as to be connectable and disconnectable. The ring gear 24 of the second gear set 20 and the carrier 33 of the third gear set 30 are connected to the transmission case 6 via the second brake 70 so that they can be connected and disconnected, and 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 and detachable.

  With the above-described configuration, according to the speed change mechanism 5, the forward 6 speed and the reverse speed are obtained by combining the engagement states of the first and second clutches 40 and 50 and the first, second, and third brakes 60, 70, and 80. And can be obtained. Note that the first brake 60 is engaged only at the first speed at which the engine brake is operated, and at the first speed at which the engine brake is not operated, the one-way clutch 90 is locked to form the first speed.

<First Embodiment of Friction Fastening Device>
Subsequently, 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 will be described with reference to FIG. I will explain. Although the frictional engagement device 100A can be applied to both the clutch and the brake, a case where it is applied to the first clutch 40 will be described for convenience of explanation.

  The first clutch 40 has a drum 41 and a hub 42. In the first clutch 40, the drum 41 is arranged on the left side in FIG. 2 and connected to the sun gears 11 and 21 of the first gear set 10 and the second gear set 20, and the hub 42 is arranged on the right side and connected to the input shaft 4. Has been.

  The drum 41 has a cylindrical shape and is rotated or stopped. The drum 41 has an end wall 41a at one end, and a plurality of notches 41b that are long in the axial direction into which a connecting portion 113c of the polymer actuator 103 described later is fitted. On the inner peripheral surface of the drum 41, a support wall 41c for supporting an annular polymer actuator 130 (described later) extending inward in the radial direction is formed.

  The hub 42 has a cylindrical shape having a smaller diameter than the drum 41, and is disposed concentrically with the drum 41 inside the drum 41. An end wall 42a is provided at one end of the hub 42 on the side opposite to the drum, and the end wall 42a is further extended radially outward to form a cylindrical portion 42b on the outer periphery. The cylindrical portion 42b has a larger diameter than the drum 41 and is formed so as to cover an end portion where the notch 41b of the drum 41 is formed.

  A friction fastening device 100 </ b> A 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 piston 102 that presses the friction plates 101a and 101b, a polymer actuator 103 that drives the piston 102, and a plurality of power transmission units 113. ing.

  Among the plurality of friction plates 101a and 101b, the plurality of friction plates 101a disposed on the inner side of the drum 41 are spline-coupled to the drum 41 so as to be movable in the axial direction and to be rotatable integrally with the drum 41. Has been. The plurality of friction plates 101b disposed on the outer side of the hub 42 are splined to the hub 42 so as to be movable in the axial direction and so as to be rotatable integrally 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 materials 101c provided on both surfaces of the friction plate 101b of the hub 42.

  The piston 102 has a cylindrical shape and is disposed 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 is a pressing portion 102a that presses the friction plates 101a and 101b. The end of the piston 102 on the side opposite to the friction plate is coupled to a movable plate 105 of a polymer actuator 130 described later. The piston 102 is preferably splined to the inner periphery of the support wall 41 c of the drum 41.

  As shown in FIG. 3, the first polymer actuator 103 includes a support plate 104, a movable plate 105, and a polymer member 106.

  The support plate 104 has an annular shape, and as shown in FIG. 3, a first electrode plate 104 a is integrally provided on a surface facing the polymer member 106. The support plate 104 and the first electrode plate 104a are electrically insulated. The surface of the support plate 104 opposite to the polymer member is coupled to the support wall 41 c of the drum 41. The first electrode plate 104a is electrically connected to the first terminal 104b. The first terminal 104 b is connected to a first contact 107 provided on the support wall 41 c of the drum 41.

  The movable plate 105 has an annular shape, and a second electrode plate 105 a is integrally provided on a surface facing the polymer member 106. The movable plate 105 and the second electrode plate 105a are electrically insulated. 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 determined by the end face of the piston 102. The second electrode plate 105a is electrically connected to the second terminal 105b. The second terminal 105 b is connected to the second contact 110 provided on the support wall 41 c of the drum 41 via the piston 102.

  The polymer member 106 has an annular shape, one end surface is joined to the first electrode plate 104 a of the support plate 104, and the other end surface is connected to the second electrode plate 105 a of the movable plate 105. The polymer member 106 is obtained by laminating an elastomer 106a such as acrylic or silicon having a high dielectric constant and elasticity and an intermediate electrode 106b in the axial direction. One of the opposed 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, it contracts in the thickness direction as shown in FIG. 3B from the state of FIG. When the voltage is released, the state returns to the state of FIG.

The required displacement amount of the polymer member 106 is calculated by (clutch clearance + clutch wear amount) × number of friction plates. When the clutch clearance is 0.3 mm, the clutch wear amount is 0.1 mm, and the number of friction plates is four, the required displacement amount of the polymer member 106 is 1.2 mm.
The force generated when a voltage is applied to the polymer member 106 is determined by the relative dielectric constant of the material × the dielectric constant of the vacuum × (voltage / film thickness) ² , and the displacement is the relative dielectric constant of the material × the dielectric constant of the vacuum × Since (voltage / film thickness) ² / elastic coefficient is obtained, the smaller the film thickness, the greater the generated force and displacement. For this reason, it is preferable that the polymer member 106 is formed by laminating as many elastomers as thin as possible to obtain a necessary displacement amount. Further, by providing a plurality of polymer actuators 103, the generated force obtained by one polymer actuator 103 can be doubled by the number of polymer actuators 103.

  The first electrode plate 104 a of the support plate 104 of the polymer actuator 103 is connected to one electrode of the power supply 109 provided outside through the bearing portion of the drum 41. Similarly, the second electrode plate 105a of the movable plate 105 of the polymer actuator 103a has a switch 112 that is turned on / off by a control device (not shown) on the other electrode of the power source 109 via a bearing portion (not shown) of the piston 102 and the drum. Connected through.

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

  The plurality of power transmission portions 113 respectively include a base portion 1113a located on the polymer member 106 side of the polymer actuator 103, an engagement portion 113b located on the cylindrical portion 42b side of the hub 41, and a base portion 113b and an engagement portion. It is comprised with the connection part 113c to connect.

  As shown in FIG. 5, the base 113 a has a ring shape that circumscribes the polymer member 106 of the polymer actuator 103. The base portion 113a can be elastically deformed outward in the radial direction by the extension of the polymer member 106 in the surface direction. As shown in FIG. 5B, the base portion 113 is not a ring shape but a segment shape divided in the circumferential direction, so that the polymer member 106 is not elastically deformed by stretching in the surface direction of the polymer member 106. The pressing force in the surface direction, that is, the radial direction of 106 can be directly applied 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 engagement surface 113d has a friction coefficient μ2 (μ2 <μ1) smaller than the friction coefficient μ1 between the first friction plate 101a and the second friction plate 101b.

  The connecting portion 113c has a plurality of pin shapes that connect the outer surface of the base portion 113a and the inner surface of the engaging portion 113b. The connecting portion 113 c is arranged so as to engage with the notch 41 b of the drum 41 so that the base portion 113 a at one end is located inside the drum 41 and the engaging portion 113 b at the other end is located outside the drum 41.

  As shown in FIG. 5, the plurality of power transmission units 113 are arranged at four equal intervals in the circumferential direction. The number of power transmission parts 113 should just be three or more, and is not limited to four.

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

  Referring to FIG. 2A, when the first clutch 40 is not engaged, the drum 41 and its friction plate 101a, the piston 102, and the polymer actuator 103 rotate together with the input shaft (not shown), and the hub 42 and its friction plate. 101b is stopped or rotating. When the switch 112 is turned on by an engagement command for 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 actuator 103 causes the polymer member 106 to contract in the axial direction (thickness direction) and expand in the radial direction (plane direction). Displace. The friction fastening device 113 performs a two-stage fastening operation in the first half and the second half of the displacement of the polymer actuator 103.

  In the first half of the 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. Since the engagement surface 113d of the engagement portion 113b has a small friction coefficient μ2, the slip starts smoothly with respect to the inner surface of the cylindrical portion 42b of the hub 42. Transmission of power from the drum 41 to the hub 42 is performed gradually.

  In the latter half of the displacement of the polymer actuator 103, as shown in FIG. 2C, the polymer member 106 contracts in the axial direction, and the movable member 105 presses the piston 102. As a result, the piston 102 moves toward the friction plate, 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 is engaged. The friction plate 101b rotates together with the drum 41 and the friction plate 101a, 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.

  When the switch 112 is turned off by the release command of the first clutch 40, the application of voltage to the polymer actuator 103 is canceled, and the polymer member 106 of the polymer actuator 103 returns due to inherent elasticity. Thereby, the movable member 105 pulls back the piston 102, the piston 102 moves toward the anti-friction plate side, and the pressing of the friction plate 101a of the drum 41 and the friction plate 101b of the hub 42 is eliminated. On the other hand, the power transmission unit 113 moves back inward in the radial direction, and the engaging portion 113 b of the power transmission unit 113 is separated from the cylindrical portion 42 b 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 interrupted.

  In the friction fastening device 100A of the above embodiment, in addition to the pressing of the friction plates 101a and 101b by the pressing portion 102a of the piston 102, power transmission is performed to the hub 42 by the power transmission portion 113, so that the amount of fastening torque increases. The increase in the pressing force of the polymer actuator having a large displacement but a small pressing force can be ensured. As a result, the friction fastening device 100A can be hydraulicless, and the driving resistance can be reduced, and the automatic transmission 1 can be reduced in weight and size.

  Further, the friction fastening device 100A can directly apply the axial pressing force due to the axial displacement of the polymer member 106 to the piston 102 via the movable plate 105 having the electrode plate 104a, so that the piston 102 is compact. And the structure becomes simple.

  In the friction fastening device 100 </ b> A, the power transmission portion 113 faces the base portion 113 a that contacts the outer surface in the radial direction of the polymer actuator 103 and the inner surface of the hub 42, and the inner surface of the hub 42 is displaced by the radial displacement of the polymer actuator 103. Since the engaging portion 113 b to be engaged 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 friction fastening device 100A starts a slip smoothly between the power transmission unit 113 and the drum 42 by the power transmission unit 113 having a low friction coefficient, and then, between the drum 41 and the hub 42 by the pressing unit 102a of the piston 102. The 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 engagement portion 113b having a low friction coefficient is provided in the power transmission portion 113, but the engagement portion 113b of the power transmission portion 113 can be a dog clutch.

  Hereinafter, the friction fastening device 100B according to the second embodiment having the power transmission unit 113 using the dog clutch shown in FIG. 6 will be specifically described. The friction fastening device 100B of the second embodiment is the same as the friction 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 engagement portion 113b of the power transmission portion 113 is different. Therefore, the same portions are denoted by the same reference numerals and the description thereof is omitted.

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

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

  Referring to FIG. 6A, when the first clutch 40 is not engaged, the drum 41 and its friction plate 101a, the piston 102, and the polymer actuator 103 rotate together with an input shaft (not shown), and the hub 42 and its friction plate. 101b is stopped or rotating. When the switch 112 is turned on by an engagement command for the first clutch 40, the voltage of the power source 109 is applied to the polymer actuator 103. Accordingly, as shown in FIGS. 6B and 6C, the polymer actuator 103 is configured so that the polymer member 106 contracts in the axial direction (thickness direction) and expands in the radial direction (plane direction). Displace. The friction fastening device 113 performs a two-stage fastening operation in the first half and the second half of the displacement of the polymer actuator 103.

  In the first half of the displacement of the polymer actuator 103, the movable member 105 presses the piston 102 by contraction in the axial direction of the polymer member 106, as shown in FIG. As a result, the piston 102 moves toward the friction plate, 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 is engaged. The friction plate 101b rotates together with the drum 41 and the friction plate 101a, 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.

  In the latter half of the displacement of the polymer actuator 103, as shown in FIG. 6C, the unevenness 113f of the engaging portion 113b of the power transmission portion 113 and the unevenness 113e of the inner surface of the cylindrical portion 42b of the hub 42 are engaged with each other. 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 application of voltage to the polymer actuator 103 is canceled, and the polymer member 106 of the polymer actuator 103 returns due to inherent elasticity. Thereby, 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, and the piston 102 moves toward the anti-friction plate side, so that the friction plate 101a of the drum 41 and the friction plate 101b of the hub 42 are not pressed. 6 (a), 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 interrupted.

  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, so that reliable power transmission is performed. be able to.

  The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, when applied to a brake, the ring gear of the gear set is a hub in the above embodiment, but the pinion carrier may be a hub.

As described above, the friction engagement device according to the present invention may be suitably used for a clutch and a brake of an automobile transmission.

DESCRIPTION OF SYMBOLS 1 Automatic transmission 41 Drum 42 Hub 42b Cylinder part 100A, 100B Friction fastening apparatus 101a, 101b Friction plate 102 Piston 102a Press part 103 Polymer actuator 104 Support plate 105 Movable plate 106 Polymer member 113 Power transmission part 113a Base 113b Engagement Part 113c coupling part 113d engagement surface 113e unevenness (dog clutch)
113f Concavity and convexity (dog clutch)

Claims (5)

A friction fastening device comprising a plurality of friction plates provided between a drum and a hub and alternately engaging with the drums and the hub, and a piston having a pressing portion that presses the plurality of friction plates and fastens them to each other. Because
A polymer actuator is provided between the drum and the piston to apply an axial pressing force to the piston,
A friction fastening device including a power transmission unit configured to transmit power to the hub by a radial displacement caused by an axial displacement of the polymer actuator.   The polymer actuator includes 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 coupled to the piston. The friction fastening device according to claim 1.   The power transmission portion includes a base portion that contacts a 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 by a radial displacement of the polymer actuator. The friction fastening device according to claim 1 or 2.   The frictional engagement 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 the friction plate, and is configured to transmit power before being pressed by the piston. apparatus.   The friction fastening device according to claim 3, wherein the engaging portion of the power transmission portion is a dog clutch that engages with the hub, and is configured to transmit power after being pressed by the piston.

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