JP2018173142A - Engaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engaging device which can be downsized.SOLUTION: An engaging device includes a hub which has an outer peripheral surface provided with a first spline extending in axial direction; a drum which stores the hub so as to rotate about the hub, and has an inner peripheral surface provided with a second spline extending in the axial direction; a plurality of inner friction plates which are spline-fitted with the first spline; a plurality of outer friction plates which are spline-fitted with the second spline and alternately disposed with the plurality of inner friction plates in the axial direction; a pressing portion which can press the inner friction plates and the outer friction plates in the axial direction; and an actuator which has a cylindrical electrode extending in the axial direction, and a cylindrical charging member extending in the axial direction and having electric charge, in which a first peripheral surface of the electrode turning in one direction in the diametrical direction faces a second peripheral surface of the charging member turning in the other direction in the diametrical direction at an interval, and in which voltage with the same positive or negative voltage as the electric charge of the charging member is applied on the electrode to press the pressing portion toward the plurality of inner friction plates and the plurality of outer friction plates with the charging member.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an engagement device.

  An engagement device for engaging two relatively rotatable parts with each other is provided in the power transmission device. The engaging device includes, for example, a plurality of inner friction plates fitted to the inner hub splines so as to be axially movable, and a plurality of outer friction plates fitted to the outer drum splines so as to be movable in the axial direction. And a pressing portion that presses or opens the alternately arranged inner friction plates and outer friction plates in the axial direction.

  By pressing the inner friction plate and the outer friction plate in which the pressing portions are alternately arranged in the axial direction, the inner friction plate and the outer friction plate come into contact with each other. That is, the inner friction plate and the outer friction plate are frictionally engaged, and the relative rotation between the hub and the drum is limited.

  On the other hand, the inner friction plate and the outer friction plate are released by separating from the inner friction plate and the outer friction plate in which the pressing portions are alternately arranged. When the opened inner friction plate and outer friction plate are separated from each other, the rotating elements respectively connected to the hub and the drum can relatively rotate (idle).

  Conventionally, for example, an electromagnetic actuator drives a pressing portion (for example, Patent Document 1). The electromagnetic actuator causes the armature to press the inner friction plate and the outer friction plate by energizing the electromagnetic coil of the electromagnet, and frictionally engages the inner friction plate and the outer friction plate.

JP 2003-148517 A

  The electromagnetic actuator presses the inner friction plate and the outer friction plate with a relatively large force in order to frictionally engage the inner friction plate and the outer friction plate. In order to generate such a large force, the electromagnetic coil of the electromagnetic actuator may be enlarged, and the engagement device will be enlarged.

  An example of the problem to be solved by the present invention is to provide an engagement device that can be miniaturized.

  The engagement device of the present invention includes, for example, a hub, a drum, a plurality of inner friction plates, a plurality of outer friction plates, a pressing portion, and an actuator. The hub has an outer peripheral surface provided with a first spline extending in the axial direction. The drum has at least a part of the hub rotatably with respect to the hub and has an inner peripheral surface provided with a second spline extending in the axial direction. The plurality of inner friction plates are spline fitted to the first spline. The plurality of outer friction plates are spline-fitted to the second spline and are alternately arranged with the plurality of inner friction plates in the axial direction. The pressing portion can press the plurality of inner friction plates and the plurality of outer friction plates in the axial direction. The actuator includes a cylindrical electrode extending in the axial direction and a cylindrical charging member extending in the axial direction and having an electric charge, and has a first circumference of the electrode facing in one direction in the radial direction. A surface of the charging member faces the second peripheral surface of the charging member facing in the other direction in the radial direction with a space therebetween, and the charging member is applied with a voltage having the same positive and negative charge as the charging member. Presses the pressing portion toward the plurality of inner friction plates and the plurality of outer friction plates.

  According to the above configuration, the actuator is an electrostatic actuator in which the charging member presses the pressing portion toward the inner friction plate and the outer friction plate by applying a voltage having the same positive and negative as the charge of the charging member to the electrode. is there. As described above, since the electrostatic actuator presses the pressing portion, a coil is not necessary compared to the case where the solenoid actuator presses the pressing portion, and the actuator can be reduced in size and weight. By forming the electrodes and charging members of the electrostatic actuator in a cylindrical shape, it is possible to ensure a large electrostatic force of the electrostatic actuator that is proportional to the facing area. Therefore, the size of the engagement device can be reduced.

FIG. 1 is a cross-sectional view showing a part of an automatic transmission provided in a vehicle according to a first embodiment. FIG. 2 is a cross-sectional view schematically showing a part of the engagement device of the first embodiment. FIG. 3 is a perspective view schematically showing two electrodes and one charging member of the first embodiment. FIG. 4 is a diagram schematically illustrating the actuator in a standby state according to the first embodiment. FIG. 5 is a diagram schematically illustrating the actuator in the driving state according to the first embodiment. FIG. 6 is a cross-sectional view illustrating a part of the automatic transmission having the actuator in the driving state according to the first embodiment. FIG. 7 is a cross-sectional view showing a part of the automatic transmission provided in the vehicle according to the second embodiment. FIG. 8 is a cross-sectional view showing a part of an automatic transmission having an actuator in a driving state according to the second embodiment.

(First embodiment)
Hereinafter, a first embodiment will be described with reference to FIGS. 1 to 6. In the present specification, a plurality of expressions may be described for the constituent elements according to the embodiment and the description of the elements. The constituent elements and descriptions in which a plurality of expressions are made may be other expressions that are not described. Further, the constituent elements and descriptions that are not expressed in a plurality may be expressed in other ways that are not described.

  FIG. 1 is a cross-sectional view showing a part of an automatic transmission 11 provided in a vehicle 10 according to the first embodiment. The vehicle 10 includes an automatic transmission 11 and an ECU 12. The automatic transmission 11 transmits a force generated by a power source such as an engine to a shaft or a tire, and may be referred to as a power transmission device. The automatic transmission 11 has an engagement device 15.

  The engagement device 15 in the present embodiment is a brake device for the automatic transmission 11. The engagement device 15 locks the predetermined gear to the case of the automatic transmission 11 in order to cause a predetermined gear of the planetary gear in the gear train to act as a reaction force element with respect to other gears. The engaging device may be another device.

  The engaging device 15 includes a hub 21, a drum 22, a plurality of inner friction plates 23, a plurality of outer friction plates 24, a pressing portion 25, an actuator 26, a plurality of return springs 27, and a terminal block 28. Have FIG. 1 shows one of a plurality of return springs 27.

  Each of the hub 21 and the drum 22 may also be referred to as a rotating element. The inner friction plate 23 can also be referred to as a disk, for example. The outer friction plate 24 can also be referred to as a separator plate, for example. The pressing part 25 may also be referred to as an apply tube. The return spring 27 is an example of an elastic body.

  The hub 21 and the drum 22 are relatively rotatable around a rotation center AX shown in FIG. Hereinafter, a direction in which the rotation center AX extends is referred to as an axial direction, a direction orthogonal to the rotation center AX is referred to as a radial direction, and a direction rotating around the rotation center AX is referred to as a circumferential direction.

  The inner peripheral portion of the inner friction plate 23 is fitted to the hub 21. The outer peripheral portion of the outer friction plate 24 is fitted to the drum 22. The pressing portion 25 presses the inner friction plate 23 and the outer friction plate 24 in the axial direction and frictionally engages them.

  For example, the hub 21 is integrated (connected) to a sun gear of a planetary gear and rotates integrally with the sun gear. For example, the drum 22 is fixed to the case of the automatic transmission 11 so as not to rotate.

  The inner friction plate 23 fitted to the hub 21 is an annular member in which a friction material is attached to both surfaces in the axial direction. Note that the inner friction plate 23 may be an annular member having no friction material and having smooth both axial surfaces. The outer friction plate 24 fitted to the drum 22 is an annular member in which both axial surfaces are formed smoothly. The outer friction plate 24 may be an annular member in which a friction material is attached to both axial surfaces. That is, in the engagement device 15, a friction material may be attached to either the inner friction plate 23 or the outer friction plate 24, or the friction material is applied to both the inner friction plate 23 and the outer friction plate 24. It may be affixed. Thus, each of the inner friction plate 23 and the outer friction plate 24 is not limited to a member to which a friction material is attached. In the wet friction engagement device, the inner friction plate 23 and the outer friction plate 24 generate a frictional force (resistance) by being close to and in contact with each other, thereby generating frictional engagement.

  The hub 21 includes a cylindrical portion 211 and a wall portion 212. The cylindrical part 211 and the wall part 212 are integrally formed by casting an aluminum alloy, for example. The cylindrical part 211 is formed in a substantially cylindrical shape extending in the axial direction. The wall 212 is formed in a substantially disk shape extending radially inward from one end of the cylindrical portion 211 in the axial direction. Wall portion 212 is connected to the sun gear.

  A plurality of outer splines 215 are provided on the outer peripheral surface 211 a of the cylindrical portion 211. The outer spline 215 is an example of a first spline. The outer peripheral surface 211a faces outward in the radial direction. The outer spline 215 protrudes radially outward from the outer peripheral surface 211a and extends in the axial direction.

  The outer spline 215 engages with an uneven portion provided on the inner peripheral portion of the inner friction plate 23. As a result, the plurality of inner friction plates 23 are spline-fitted to the outer spline 215 so as to be movable in the axial direction.

  The hub 21 is disposed inside the drum 22 so as to be rotatable around the rotation center AX with respect to the drum 22. In other words, the drum 22 accommodates the hub 21 so as to be rotatable with respect to the hub 21. A part of the hub 21 may be located outside the drum 22.

  The drum 22 includes a first cylinder part 221, a first wall part 222, a second cylinder part 223, a second wall part 224, and a third cylinder part 225. The first cylinder part 221, the first wall part 222, the second cylinder part 223, the second wall part 224, and the third cylinder part 225 are integrally formed, for example, by casting an aluminum alloy. The

  The 1st cylinder part 221 is formed in the substantially cylindrical shape extended in an axial direction. The first wall portion 222 is formed in a substantially annular shape extending radially inward from one end portion in the axial direction of the first cylindrical portion 221.

  The second cylindrical portion 223 is formed in a substantially cylindrical shape that extends in the axial direction from the radially inner end of the first wall portion 222. The first cylinder part 221 and the second cylinder part 223 extend from the first wall part 222 in opposite directions.

  The second wall portion 224 is formed in a substantially disc shape that extends radially inward from one end portion in the axial direction of the second cylindrical portion 223. The second wall portion 224 is integrated (connected) to the case of the automatic transmission 11 so as not to rotate.

  The third cylindrical portion 225 is formed in a substantially cylindrical shape that extends from the second wall portion 224 in the axial direction. The third cylinder part 225 is located inside the second cylinder part 223. The second cylinder part 223 and the third cylinder part 225 extend from the second wall part 224 in the same direction.

  A plurality of inner splines 227 are provided on the inner peripheral surface 221 a of the first cylindrical portion 221. The inner spline 227 is an example of a second spline. The inner peripheral surface 221a faces inward in the radial direction. The inner spline 227 protrudes radially inward from the inner peripheral surface 221a and extends in the axial direction. The hub 21 is located inside the first cylindrical portion 221. For this reason, the inner peripheral surface 221 a of the first cylindrical portion 221 faces the outer peripheral surface 211 a of the cylindrical portion 211 of the hub 21.

  The inner spline 227 engages with an uneven portion formed on the outer peripheral portion of the outer friction plate 24. As a result, the plurality of outer friction plates 24 are spline-fitted to the inner spline 227 so as to be movable in the axial direction. The inner splines 227 are alternately arranged with a plurality of outer splines 215 fitted to the hub 21 in the axial direction.

  The drum 22 further includes a first retainer 228 and a snap ring 229. The first retainer 228 and the snap ring 229 are provided separately from the first cylinder part 221, the first wall part 222, the second cylinder part 223, the second wall part 224, and the third cylinder part 225. Provided.

  The first retainer 228 is formed in a substantially annular shape. For example, the inner spline 227 engages with the concavo-convex portion provided on the outer peripheral portion of the first retainer 228. The 1st retainer 228 contacts the backing plate 24a located in an end among the outer friction plates 24 arranged in the axial direction.

  The snap ring 229 is formed in a substantially annular shape. For example, the snap ring 229 is fitted into a groove provided in the inner spline 227 and is fixed to the inner spline 227. The snap ring 229 supports the backing plate 24 a in the axial direction via the first retainer 228.

  The pressing portion 25 includes a first pressure receiving wall 251, a first cylindrical wall 252, a second pressure receiving wall 253, a second cylindrical wall 254, and a third pressure receiving wall 255. The first pressure receiving wall 251, the first cylindrical wall 252, the second pressure receiving wall 253, the second cylindrical wall 254, and the third pressure receiving wall 255 are integrally formed, for example, by casting an aluminum alloy. The

  The first pressure receiving wall 251 is formed in a substantially annular shape extending radially inward from one end portion in the axial direction of the first cylindrical wall 252. The first cylindrical wall 252 is formed in a substantially cylindrical shape extending in the axial direction. The second pressure receiving wall 253 is formed in a substantially disc shape that extends radially outward from the other end in the axial direction of the first cylindrical wall 252.

  The second cylindrical wall 254 is formed in a substantially cylindrical shape that extends in the axial direction from the radially outer end of the second pressure receiving wall 253. The third pressure receiving wall 255 is formed in a substantially disc shape that extends radially outward from the end of the second cylindrical wall 254 in the axial direction. The third pressure receiving wall 255 is located on the opposite side of the second pressure receiving wall 253.

  The first pressure receiving wall 251 is closer to the second wall portion 224 of the drum 22 than the second pressure receiving wall 253 and the third pressure receiving wall 255. The third pressure receiving wall 255 is farther from the second wall portion 224 of the drum 22 than the first pressure receiving wall 251 and the second pressure receiving wall 253.

  The inner spline 227 is engaged with the concavo-convex portion provided on the outer peripheral portion of the third pressure receiving wall 255. Thereby, the pressing part 25 is spline fitted to the inner spline 227 so as to be movable in the axial direction. In other words, the inner spline 227 supports the pressing portion 25 so as to be movable in the axial direction.

  The first pressure receiving wall 251 has a first pressure receiving surface 251a. The second pressure receiving wall 253 has a second pressure receiving surface 253a. The third pressure receiving wall 255 has a third pressure receiving surface 255a. The first to third pressure receiving surfaces 251 a, 253 a, and 255 a face the second wall portion 224 of the drum 22.

  The third pressure receiving wall 255 has a pressing surface 255b. The pressing surface 255b is located on the opposite side of the third pressure receiving surface 255a. The pressing surface 255b faces the plurality of inner friction plates 23 and the plurality of outer friction plates 24 that are alternately arranged.

  The pressing part 25 further includes a second retainer 257. The second retainer 257 is provided separately from the first pressure receiving wall 251, the first cylindrical wall 252, the second pressure receiving wall 253, the second cylindrical wall 254, and the third pressure receiving wall 255.

  The second retainer 257 is formed in a substantially annular shape. For example, the inner spline 227 is engaged with the uneven portion provided on the outer peripheral portion of the second retainer 257. The second retainer 257 is fixed to the pressing surface 255 b of the third pressure receiving wall 255. Between the third pressure receiving wall 255 and the snap ring 229, a first retainer 228, a plurality of inner friction plates 23, a plurality of outer friction plates 24, and a second retainer 257 are disposed.

  FIG. 2 is a cross-sectional view schematically showing a part of the engagement device 15 of the first embodiment. The actuator 26 shown in FIG. 2 is a so-called electrostatic actuator. The actuator 26 includes a plurality of electrodes 261, a plurality of charging members 262, a power supply 263, a first wiring 264, a second wiring 265, a third wiring 266, and a switch 267.

  FIG. 3 is a perspective view schematically showing two electrodes 261 and one charging member 262 of the first embodiment. As shown in FIG. 3, the electrode 261 is formed in a substantially cylindrical shape (tubular shape) extending in the axial direction. The electrode 261 is made of a conductor such as copper.

  As shown in FIG. 2, the electrode 261 has an inner peripheral surface 261a and an outer peripheral surface 261b. Each of the inner peripheral surface 261a and the outer peripheral surface 261b is an example of a first peripheral surface. The inner peripheral surface 261a faces inward in the radial direction. The outer peripheral surface 261b is located on the opposite side of the inner peripheral surface 261a and faces outward in the radial direction. Each of the radially inner side and the radially outer side is an example of one direction in the radial direction.

  The radii of the plurality of electrodes 261 are different from each other. The plurality of electrodes 261 are arranged concentrically with intervals in the radial direction. In other words, the plurality of electrodes 261 are overlapped in the radial direction at intervals. The plurality of electrodes 261 include a plurality of types of electrodes 261 having different lengths in the axial direction. One end portion of the electrode 261 in the axial direction is fixed to the second wall portion 224 of the drum 22.

  As shown in FIG. 3, the charging member 262 is formed in a substantially cylindrical shape (tubular shape) extending in the axial direction. As shown in FIG. 1, the charging member 262 has an inner peripheral surface 262a, an outer peripheral surface 262b, a first end 262c, and a second end 262d. Each of the inner peripheral surface 262a and the outer peripheral surface 262b is an example of a second peripheral surface.

  The inner peripheral surface 262a faces inward in the radial direction. The outer peripheral surface 262b is located on the opposite side of the inner peripheral surface 262a and faces radially outward. The radially outer side and the radially inner side are examples of other directions in the radial direction.

  The first end 262c is one end of the charging member 262 in the axial direction. The first end 262 c faces the second wall 224 of the drum 22. The second end 262d is the other end of the charging member 262 in the axial direction, and is located on the opposite side of the first end 262c. The second end portion 262d faces the pressing portion 25.

  The plurality of charging members 262 include a plurality of types of charging members 262 having different lengths in the axial direction. The second end portions 262d of the plurality of charging members 262 are in contact with the first pressure receiving surface 251a, the second pressure receiving surface 253a, or the third pressure receiving surface 255a of the pressing portion 25, respectively.

  As shown in FIG. 2, each of the plurality of charging members 262 includes a base 262e and two electrets 262f. The base 262e and the electret 262f are each formed in a substantially cylindrical shape.

  The base 262e is made of, for example, a conductor. Note that the base 262e may be made of another material such as an insulator. The two electrets 262f are attached to both surfaces in the radial direction of the base 262e. For this reason, the two electrets 262f form an inner peripheral surface 262a and an outer peripheral surface 262b of the charging member 262.

  The electret 262f forming the inner peripheral surface 262a is dielectrically polarized so that the inner peripheral surface 262a has a negative charge. The electret 262f holds negative charges on the inner peripheral surface 262a.

  The electret 262f forming the outer peripheral surface 262b is dielectrically polarized so that the outer peripheral surface 262b has a negative charge. The electret 262f holds negative charges on the outer peripheral surface 262b.

  Thus, the two electrets 262f have the same positive and negative charges on the inner peripheral surface 262a and the outer peripheral surface 262b. The two electrets 262f may have positive charges on the inner peripheral surface 262a and the outer peripheral surface 262b.

  The radii of the plurality of charging members 262 are different from each other. The plurality of charging members 262 are arranged concentrically with intervals in the radial direction. In other words, the plurality of charging members 262 are overlapped in the radial direction at intervals.

  The plurality of electrodes 261 and the plurality of charging members 262 are stacked (overlapped) with an interval in the radial direction. The plurality of electrodes 261 and the plurality of charging members 262 are alternately arranged in the radial direction. The length of each of the plurality of electrodes 261 is substantially equal to the length of the charging member 262 adjacent to the radially inner side or the radially outer side. The plurality of charging members 262 are alternately arranged with the plurality of electrodes 261 so as to be movable in the axial direction with respect to the plurality of electrodes 261.

  The inner peripheral surface 261a of the electrode 261 and the outer peripheral surface 262b of the charging member 262 face each other with a gap in the radial direction. Further, the outer peripheral surface 261b of the electrode 261 and the inner peripheral surface 262a of the charging member 262 face each other with a gap in the radial direction.

  In the present embodiment, the number of electrodes 261 is larger than the number of charging members 262. Therefore, the inner peripheral surface 262a and the outer peripheral surface 262b of all the charging members 262 face the outer peripheral surface 261b or the inner peripheral surface 261a of the electrode 261, respectively. On the other hand, the inner peripheral surface 261 a of the innermost electrode 261 faces the third cylindrical portion 225. Further, the outer peripheral surface 261 b of the electrode 261 located on the outermost side faces the second cylindrical portion 223. Note that the number of electrodes 261 and the number of charging members 262 may be the same, or the number of electrodes 261 may be smaller than the number of charging members 262.

  As shown in FIG. 3, the actuator 26 may further include a plurality of spacers 268. Each of the spacers 268 is attached to the inner peripheral surface 262a or the outer peripheral surface 262b of the charging member 262 and extends in the axial direction.

  The spacer 268 is made of an insulator having a low friction coefficient, for example. The spacer 268 is interposed between the electrode 261 and the charging member 262. The charging member 262 is disposed so that the spacer 268 is separated from the electrode 261.

  When the charging member 262 approaches the electrode 261, the spacer 268 contacts the electrode 261 and keeps a gap between the electrode 261 and the charging member 262. Thereby, the spacer 268 suppresses the electrode 261 and the charging member 262 from being electrically connected.

  As shown in FIG. 1, the drum 22 is provided with an annular recess 22a. The annular recess 22a is formed by the second cylinder part 223, the second wall part 224, and the third cylinder part 225, and is recessed in the axial direction. A plurality of electrodes 261 and a plurality of charging members 262 are disposed in the annular recess 22a. In other words, the plurality of electrodes 261 and the plurality of charging members 262 are disposed between the second cylinder portion 223 and the third cylinder portion 225 in the radial direction.

  As shown in FIG. 2, the power supply 263 is a DC power supply. The power supply 263 may be a unit having a diode and an AC power supply, for example, as long as it can output a DC voltage. Further, the power source 263 may be capable of changing the voltage. The positive electrode of the power supply 263 is connected to the ground G.

  The first wiring 264 connects the ground G and the switch 267 to the plurality of charging members 262 in parallel. The first wiring 264 includes a movable wiring 264a. The movable wiring 264 a is a part of the first wiring 264 and is connected to the charging member 262.

  The movable wiring 264a is, for example, a spring-like conductor that can expand and contract in the axial direction, or two conductors that are relatively movable in the axial direction and are in contact with each other. By providing the movable wiring 264 a, when the charging member 262 moves in the axial direction with respect to the electrode 261, the first wiring 264 maintains the connection between the charging member 262, the ground G, and the switch 267.

  The second wiring 265 connects the switch 267 to the plurality of electrodes 261 in parallel. The third wiring 266 connects the switch 267 and the negative electrode of the power supply 263. The switch 267 is a three-way switch and can switch between a state in which the second wiring 265 is connected to the first wiring 264 and a state in which the second wiring 265 is connected to the third wiring 266.

  FIG. 4 is a diagram schematically illustrating the actuator 26 in the standby state according to the first embodiment. As shown in FIG. 4, in a state where the second wiring 265 is connected to the first wiring 264 (standby state), the electrode 261 is connected to the ground G via the second wiring 265 and the first wiring 264. Connected. In other words, the electrode 261 is grounded.

  The inner peripheral surface 262a and the outer peripheral surface 262b of the charging member 262 having a negative charge face the outer peripheral surface 261b and the inner peripheral surface 261a of the electrode 261. For this reason, the outer peripheral surface 261b and the inner peripheral surface 261a of the electrode 261 have positive charges due to electrostatic induction. Electrons of the electrode 261 flow to the ground G through the second wiring 265 and the first wiring 264.

  The actuator 26 in FIG. 1 is in a standby state. In the standby state, the first end 262 c of the charging member 262 is supported by the second wall 224 of the drum 22. Further, in the standby state, the electrode 261 may contact the first pressure receiving surface 251a, the second pressure receiving surface 253a, and the third pressure receiving surface 255a of the pressing portion 25.

  FIG. 5 is a diagram schematically illustrating the actuator 26 in the driving state according to the first embodiment. As shown in FIG. 5, in a state where the second wiring 265 is connected to the third wiring 266 (driving state), the electrode 261 is connected to the power supply 263 via the second wiring 265 and the third wiring 266. Connected to the negative electrode. As a result, the power supply 263 applies a negative voltage to the electrode 261. In other words, the power supply 263 applies a voltage having the same positive and negative charge to the electrode 261 as the charge of the inner peripheral surface 262 a and the outer peripheral surface 262 b of the charging member 262.

  When the power source 263 applies a negative voltage to the electrode 261, the inner peripheral surface 261a and the outer peripheral surface 261b of the electrode 261 have negative charges. However, the electret 262f maintains a dielectric polarization state and does not cause electrostatic induction. For this reason, the inner peripheral surface 262a and the outer peripheral surface 262b of the charging member 262 are kept in a state having a negative charge.

  The inner peripheral surface 261a and the outer peripheral surface 261b of the electrode 261 having a negative charge and the inner peripheral surface 262a and the outer peripheral surface 262b of the charging member 262 having a negative charge face each other. For this reason, an electrostatic force is generated, and the electrostatic force moves the charging member 262 with respect to the electrode 261. By providing the movable wiring 264 a, the plurality of moving charging members 262 are kept connected to the first wiring 264.

  FIG. 6 is a cross-sectional view showing a part of the automatic transmission 11 having the actuator 26 in the driving state according to the first embodiment. As shown in FIG. 6, when a negative voltage is applied to the electrode 261, the charging member 262 moves in a direction away from the second wall portion 224 of the drum 22. Accordingly, the plurality of charging members 262 press the pressing portion 25 toward the plurality of inner friction plates 23 and the plurality of outer friction plates 24. The charging member 262 can move to a position where the charges on the inner peripheral surface 262a and the outer peripheral surface 262b of the charging member 262 and the charges on the outer peripheral surface 261b and the inner peripheral surface 261a of the opposing electrode 261 are balanced.

  In the standby state, the first end portion 262 c of the charging member 262 contacts the second wall portion 224. For this reason, the direction in which the charging member 262 moves due to the electrostatic force is limited to the direction toward the plurality of inner friction plates 23 and the plurality of outer friction plates 24.

  The pressing portion 25 pressed by the charging member 262 presses the plurality of inner friction plates 23 and the plurality of outer friction plates 24 in the axial direction. For example, when the second retainer 257 presses the inner friction plate 23 toward the first retainer 228, the plurality of inner friction plates 23 and the plurality of outer friction plates 24 come into contact with each other. Thereby, the plurality of inner friction plates 23 and the plurality of outer friction plates 24 arranged alternately are frictionally engaged, and the relative rotation between the hub 21 and the drum 22 is restricted.

  The return spring 27 is, for example, a compression spring that extends in the axial direction. The plurality of return springs 27 are disposed between the first retainer 228 and the second retainer 257. The plurality of return springs 27 are arranged at substantially equal intervals in the circumferential direction.

  One end portion of the return spring 27 is supported by the convex portion 228 a of the first retainer 228. The other end of the return spring 27 is supported by the convex portion 257 a of the second retainer 257.

  The return spring 27 presses the pressing portion 25 in a direction in which the pressing portion 25 is separated from the plurality of inner friction plates 23 and the plurality of outer friction plates 24. In other words, the return spring 27 presses the pressing portion 25 toward the second wall portion 224 of the drum 22.

  As shown in FIG. 1, in the standby state, the pressing portion 25 pushed by the return spring 27 is separated from the plurality of inner friction plates 23 and the plurality of outer friction plates 24. Note that the inner friction plate 23 or the outer friction plate 24 may be close to the pressing portion 25 by opening a gap between the inner friction plate 23 and the outer friction plate 24.

  The pressing portion 25 pressed by the return spring 27 presses the plurality of charging members 262 toward the second wall portion 224. As a result, the charging member 262 is disposed at the standby position P <b> 1 where the first end 262 c contacts the second wall 224.

  In the standby position P1, the second wall 224 supports the first end 262c of the charging member 262. This restricts the return spring 27 from further moving the pressing portion 25.

  On the other hand, as shown in FIG. 6, the plurality of charging members 262 press the pressing portion 25 toward the inner friction plate 23 and the outer friction plate 24 in the driving state. The actuator 26 generates an electrostatic force larger than the elastic force of the return spring 27. For this reason, the pressing part 25 moves and presses the plurality of inner friction plates 23 and the plurality of outer friction plates 24 in the axial direction.

  When the charging member 262 reaches the engagement position P <b> 2 where the plurality of inner friction plates 23 and the plurality of outer friction plates 24 contact each other, the snap ring 229 is interposed via the plurality of inner friction plates 23 and the plurality of outer friction plates 24. The pressing part 25 is supported. Thereby, the movement of the pressing portion 25 is limited by the snap ring 229.

  When the actuator 26 changes from the driving state to the standby state, the return spring 27 presses the pressing portion 25 and returns the plurality of charging members 262 to the standby position P1. Thus, the charging member 262 is movable between the standby position P1 and the engagement position P2.

  The area where the plurality of charging members 262 and the plurality of electrodes 261 face each other at the standby position P1 is wider than the area where the plurality of charging members 262 and the plurality of electrodes 261 face each other at the engaging position P2. The magnitude of the electrostatic force generated by the actuator 26 is proportional to the area where the charging member 262 and the electrode 261 face each other. For this reason, the electrostatic force generated at the standby position P1 is larger than the electrostatic force generated at the engagement position P2. Thus, the return spring 27 moves the plurality of charging members 262 to a position where the generated electrostatic force is maximized.

  The terminal block 28 is used for connection and release between the ECU 12 and the battery and the actuator 26. For example, the cable C connected to the ECU 12 or the battery is connected to a terminal provided on the terminal block 28. As a result, as shown in FIG. 2, the electrode 261 can be electrically connected to the power supply 263, the first wiring 264, the third wiring 266, and the switch 267 through the second wiring 265.

  For example, a part of the first wiring 264 and the third wiring 266 is included in the cable C. A part of the first wiring 264, a part of the second wiring 265, a part of the third wiring 266, and the switch 267 are provided in the engagement device 15. Note that part of the first wiring 264, part of the second wiring 265, the third wiring 266, and the switch 267 may be provided outside the engagement device 15.

  The ECU 12 shown in FIG. 1 includes a CPU (Central Processing Unit), a ROM (Read Only Memory) that stores a predetermined control program and the like, a RAM (Random Access Memory) that temporarily stores the calculation results of the CPU, It is composed of a backup RAM for storing prepared information and the like.

  The ECU 12 controls the switch 267 in FIG. 2 to switch the actuator 26 between a standby state and a driving state. Further, the ECU 12 controls the voltage of the power supply 263 when the voltage of the power supply 263 can be changed.

  In the engaging device 15 according to the first embodiment described above, the inner peripheral surface 261a and the outer peripheral surface 261b of the cylindrical electrode 261 are spaced from the outer peripheral surface 262b and the inner peripheral surface 262a of the cylindrical charging member 262. Facing each other. The actuator 26 is an electrostatic actuator in which the charging member 262 presses the pressing portion 25 toward the inner friction plate 23 and the outer friction plate 24 when a voltage having the same sign as the charge of the charging member 262 is applied to the electrode 261. It is. Thus, in this embodiment, since the actuator 26 which is an electrostatic actuator presses the pressing portion 25, energy loss due to oil leakage occurring in the valve or the like is smaller than when the hydraulic servo mechanism presses the pressing portion 25. It can be prevented from occurring. Furthermore, since electricity having a higher transmission speed than hydraulic oil is used, the response speed of the actuator 26 is improved. Further, as compared with the case where the solenoid actuator presses the pressing portion 25, no coil is required, and the actuator 26 can be reduced in size and weight. By forming the electrode 261 and the charging member 262 of the actuator 26 in a cylindrical shape, a large electrostatic force of the actuator 26 that is proportional to the facing area of the electrode 261 and the charging member 262 can be secured. Therefore, the size of the engagement device 15 can be reduced.

  The return spring 27 presses the pressing portion 25 in a direction in which the pressing portion 25 is separated from the plurality of inner friction plates 23 and the plurality of outer friction plates 24. Accordingly, the return spring 27 returns the charging member 262 to the standby position P1 where the inner peripheral surface 261a and outer peripheral surface 261b of the electrode 261 and the outer peripheral surface 262b and inner peripheral surface 262a of the charging member 262 face each other in a larger area, and the actuator The electrostatic force of 26 can be increased. Further, since the pressing portion 25 is separated from the inner friction plate 23 and the outer friction plate 24, for example, when the movement of the charging member 262 is hindered by dust or the like, the hub 21 cannot rotate with respect to the drum 22. Is suppressed.

  A plurality of electrodes 261 and a plurality of charging members 262 are alternately arranged in the radial direction. Thereby, the area where the electrode 261 and the charging member 262 face each other is increased, and a large electrostatic force of the actuator 26 can be secured.

(Second Embodiment)
Hereinafter, the second embodiment will be described with reference to FIGS. 7 and 8. In the following description of the embodiment, components having the same functions as those already described are denoted by the same reference numerals as those described above, and further description may be omitted. In addition, a plurality of components to which the same reference numerals are attached do not necessarily have the same functions and properties, and may have different functions and properties according to each embodiment.

  FIG. 7 is a cross-sectional view showing a part of the automatic transmission 11 provided in the vehicle 10 according to the second embodiment. The engagement device 15 in the second embodiment is a clutch device of the automatic transmission 11. The engaging device 15 can connect a predetermined gear of the planetary gear in the gear train and another gear, and can release the connection of these gears.

  In the second embodiment, the hub 21 is integrated (connected) to the ring gear of the planetary gear, and rotates integrally with the ring gear. The drum 22 is connected to the sun gear of the planetary gear and rotates integrally with the sun gear. The hub 21 and the drum 22 are not limited to this example.

  As shown in FIG. 7, the engagement device 15 of the second embodiment further includes a fixing member 31, a retainer 32, and a snap ring 33. The fixing member 31 is integrated (connected) to the case of the automatic transmission 11 so as not to rotate. Each of the hub 21 and the drum 22 is rotatable with respect to the fixing member 31.

  The fixed member 31 is provided with a cylinder 31a. The cylinder 31a is an annular recess that is recessed in the axial direction. A plurality of electrodes 261 and a plurality of charging members 262 of the actuator 26 are disposed in the cylinder 31a.

  One end of the electrode 261 in the axial direction is fixed to the bottom surface 31b of the cylinder 31a. The bottom surface 31b is an annular plane that faces in the axial direction. The bottom surface 31b supports the first end 262c of the charging member 262 located at the standby position P1.

  The retainer 32 is formed in a substantially annular shape and is supported by a snap ring 33 attached to the fixing member 31. The snap ring 33 restricts the retainer 32 from moving in a direction away from the bottom surface 31b.

  The pressing portion 25 of the second embodiment has a piston 35, an apply tube 36, and a thrust bearing 37. The piston 35 is formed in a substantially annular shape, and is accommodated in the cylinder 31 a so as to be movable in the axial direction with respect to the fixing member 31.

  In the axial direction, a plurality of electrodes 261 and a plurality of charging members 262 are positioned between the bottom surface 31 b of the fixing member 31 and the piston 35. The second end portions 262 d of the plurality of charging members 262 are in contact with the piston 35. Furthermore, the electrode 261 may contact the piston 35 when the charging member 262 is located at the standby position P1. The piston 35 is positioned between the plurality of electrodes 261 and the plurality of charging members 262 and the retainer 32 in the axial direction.

  The apply tube 36 is positioned between the plurality of inner friction plates 23 and the plurality of outer friction plates 24 and the piston 35 in the axial direction. The apply tube 36 can rotate integrally with the drum 22.

  The apply tube 36 is supported by the piston 35 via a thrust bearing 37. The thrust bearing 37 includes a plurality of rollers disposed between the two races, and supports the apply tube 36 so as to be rotatable with respect to the piston 35. That is, the thrust bearing 37 transmits an axial force between the piston 35 and the apply tube 36 and interrupts a circumferential force (torque).

  In the second embodiment, the return spring 27 is located between the retainer 32 and the piston 35. The return spring 27 presses the piston 35 toward the bottom surface 31 b of the fixing member 31. In other words, the return spring 27 presses the piston 35 in a direction away from the plurality of inner friction plates 23 and the plurality of outer friction plates 24.

  In the second embodiment, the drum 22 does not have the first retainer 228, and the pressing portion 25 does not have the second retainer 257. The backing plate 24 a of the outer friction plate 24 is directly supported in the axial direction by the snap ring 229.

  FIG. 8 is a cross-sectional view showing a part of the automatic transmission 11 having the actuator 26 in the driving state according to the second embodiment. As illustrated in FIG. 8, in the driving state, a voltage having the same positive and negative charge as that of the inner peripheral surface 262 a and the outer peripheral surface 262 b of the charging member 262 is applied to the electrode 261.

  The inner peripheral surface 261a and the outer peripheral surface 261b of the electrode 261 having a negative charge and the inner peripheral surface 262a and the outer peripheral surface 262b of the charging member 262 having a negative charge face each other. Thereby, the electrostatic force moves the charging member 262 relative to the electrode 261.

  When a negative voltage is applied to the electrode 261, the charging member 262 moves in a direction away from the bottom surface 31 b of the fixing member 31. Thus, the plurality of charging members 262 press the apply tube 36 toward the plurality of inner friction plates 23 and the plurality of outer friction plates 24 via the pistons 35 and the thrust bearings 37.

  In the standby state, the first end 262 c of the charging member 262 contacts the bottom surface 31 b of the fixing member 31. For this reason, the direction in which the charging member 262 moves due to the electrostatic force is limited to the direction toward the plurality of inner friction plates 23 and the plurality of outer friction plates 24.

  The apply tube 36 pressed by the charging member 262 presses the plurality of inner friction plates 23 and the plurality of outer friction plates 24 in the axial direction. Thereby, the plurality of inner friction plates 23 and the plurality of outer friction plates 24 arranged alternately are frictionally engaged, and the relative rotation between the hub 21 and the drum 22 is restricted.

  As shown in FIG. 7, when the piston 35 is pushed by the return spring 27 in the standby state, the apply tube 36 is separated from the plurality of inner friction plates 23 and the plurality of outer friction plates 24. Note that the inner friction plate 23 or the outer friction plate 24 may be close to the apply tube 36 by opening a gap between the inner friction plate 23 and the outer friction plate 24.

  The piston 35 pushed by the return spring 27 presses the plurality of charging members 262 toward the bottom surface 31 b of the fixing member 31. Thus, the charging member 262 is disposed at the standby position P1 where the first end 262c contacts the bottom surface 31b.

  In the standby position P1, the bottom surface 31b supports the first end 262c of the charging member 262. This restricts the return spring 27 from moving the piston 35 further.

  On the other hand, as shown in FIG. 8, the plurality of charging members 262 press the pressing portion 25 toward the inner friction plate 23 and the outer friction plate 24 in the driving state. The actuator 26 generates an electrostatic force larger than the elastic force of the return spring 27. Therefore, the piston 35 and the apply tube 36 move and press the plurality of inner friction plates 23 and the plurality of outer friction plates 24 in the axial direction.

  When the charging member 262 reaches the engagement position P <b> 2 where the plurality of inner friction plates 23 and the plurality of outer friction plates 24 contact each other, the snap ring 229 is interposed via the plurality of inner friction plates 23 and the plurality of outer friction plates 24. The pressing part 25 is supported. Thereby, the movement of the pressing portion 25 is limited by the snap ring 229.

  As in the second embodiment described above, the engagement device 15 is not limited to the brake device, and may be another device such as a clutch device. Also in the engagement device 15 that is a clutch device, a coil is not required compared to the case where the solenoid actuator presses the pressing portion 25, and the actuator 26 can be reduced in size and weight. Further, since the electrode 261 and the charging member 262 are formed in a cylindrical shape, a large electrostatic force of the actuator 26 proportional to the facing area of the electrode 261 and the charging member 262 can be ensured. Therefore, the size of the engagement device 15 can be reduced.

  In the plurality of embodiments described above, the charging member 262 includes an electret 262f. However, the charging member 262 is not limited to this example. For example, the charging member 262 may be a conductor having a charge by applying a voltage.

  In the plurality of embodiments described above, the plurality of charging members 262 are returned from the engagement position P2 to the standby position P1 by the return spring 27. However, for example, when a positive voltage is applied to the electrode 261, the plurality of charging members 262 are returned from the engagement position P2 to the standby position P1 by the electrostatic force generated between the electrode 261 and the charging member 262. Also good.

  The above-described embodiments of the present invention do not limit the scope of the invention, but are merely examples included in the scope of the invention. An embodiment of the present invention is different from the above-described embodiment in that, for example, at least a part of a specific application, structure, shape, action, and effect is changed, omitted, and within the scope of the invention. It may be added.

The present embodiment includes at least the following configuration. A hub (21) having an outer peripheral surface (211a) provided with a first spline (215) extending in the axial direction, and at least a part of the hub (21) accommodated so as to be rotatable with respect to the hub (21) A drum (22) having an inner peripheral surface (221a) provided with a second spline (227) extending in the axial direction, and a plurality of internal frictions spline-fitted to the first spline (215) A plurality of outer friction plates (24), which are spline-fitted to the plate (23) and the second splines (227), and arranged alternately with the plurality of inner friction plates (23) in the axial direction; A pressing portion (25) capable of pressing the plurality of inner friction plates (23) and the plurality of outer friction plates (24) in the axial direction, a cylindrical electrode (261) extending in the axial direction, and the shaft With a charge that extends in the direction A charging member (262) having a shape, and a first peripheral surface (261a, 261b) of the electrode (261) facing in one direction in the radial direction, the charging member ( 262) facing the second circumferential surface (262b, 262a) of the charging member (262) by applying a voltage having the same positive and negative as the charge of the charging member (262) to the electrode (261). 262) an engagement device (15) including an actuator (26) that presses the pressing portion (25) toward the plurality of inner friction plates (23) and the plurality of outer friction plates (24). . According to this configuration, the actuator is an electrostatic actuator in which the charging member presses the pressing portion toward the inner friction plate and the outer friction plate by applying a voltage having the same positive and negative as the charge of the charging member to the electrode. is there. As described above, since the electrostatic actuator presses the pressing portion, energy loss due to oil leakage in the valve or the like is prevented as compared with the case where the hydraulic servo mechanism presses the pressing portion. Further, since electricity having a higher transmission speed than hydraulic oil is used, the response speed of the actuator is improved. Further, as compared with the case where the solenoid actuator presses the pressing portion, a coil is not necessary, and the actuator can be reduced in size and weight. By forming the electrodes and charging members of the electrostatic actuator in a cylindrical shape, it is possible to ensure a large electrostatic force of the electrostatic actuator that is proportional to the facing area. Therefore, the size of the engagement device can be reduced.
In addition, this embodiment preferably includes the following configuration. An elastic body (27) that presses the pressing portion (25) in a direction in which the pressing portion (25) moves away from the plurality of inner friction plates (23) and the plurality of outer friction plates (24). The engagement device (15). According to this configuration, the elastic body can return the charging member to a position where the outer peripheral surface and the inner peripheral surface face each other with a larger area, and the electrostatic force of the actuator can be increased. Further, since the pressing portion is separated from the inner friction plate and the outer friction plate, it is possible to prevent the hub from rotating with respect to the drum when the movement of the charging member is hindered by, for example, dust.
In addition, this embodiment preferably includes the following configuration. The actuator (26) includes a plurality of the electrodes (261) and a plurality of the charging members (262) alternately arranged with the plurality of electrodes (261) in the radial direction. 15). According to this configuration, the area where the electrode and the charging member face each other is increased, and a large electrostatic force of the actuator can be ensured.

  DESCRIPTION OF SYMBOLS 15 ... Engagement device, 21 ... Hub, 22 ... Drum, 23 ... Inner friction plate, 24 ... Outer friction plate, 25 ... Pressing part, 26 ... Actuator, 27 ... Return spring, 211 ... Cylindrical part, 211a ... Outer peripheral surface 215: outer spline, 221: first cylindrical portion, 221a: inner peripheral surface, 227 ... inner spline, 261 ... electrode, 261a ... inner peripheral surface, 261b ... outer peripheral surface, 262 ... charging member, 262a ... inner peripheral surface , 262b ... outer peripheral surface.

Claims (3)

A hub having an outer peripheral surface provided with a first spline extending in the axial direction;
A drum that has at least a part of the hub rotatably with respect to the hub and has an inner peripheral surface provided with a second spline extending in the axial direction;
A plurality of inner friction plates that are spline-fitted to the first spline;
A plurality of outer friction plates that are spline-fitted to the second spline and arranged alternately with the plurality of inner friction plates in the axial direction;
A pressing portion capable of pressing the plurality of inner friction plates and the plurality of outer friction plates in the axial direction;
A cylindrical charging member extending in the axial direction and a cylindrical charging member extending in the axial direction and having a charge, and the first peripheral surface of the electrode facing in one direction in the radial direction is The charging member is opposed to the second peripheral surface of the charging member facing in the other direction in the radial direction through a space, and the charging member is applied to the pressing portion by applying a voltage having the same positive and negative as the charge of the charging member to the electrode. An actuator that presses toward the plurality of inner friction plates and the plurality of outer friction plates;
An engagement device comprising:   The engagement device according to claim 1, further comprising an elastic body that presses the pressing portion in a direction in which the pressing portion is separated from the plurality of inner friction plates and the plurality of outer friction plates.   The engagement device according to claim 1, wherein the actuator includes a plurality of the electrodes and a plurality of the charging members that are alternately arranged with the plurality of electrodes in a radial direction.

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