JP2011057136A - Power transmission device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power transmission device to be used in an on-demand type 4WD vehicle, allowing improvement of miniaturization and supporting property. <P>SOLUTION: This power transmission device 1 includes one wheel drive shaft 7, a first hollow shaft 11, a clutch mechanism 21 comprising a plurality of inside clutch plates 13, a cylindrical housing 15, a plurality of outside clutch plates 17 and an actuator 19, a second hollow shaft 23, an output gear 25, a transmission gear 29 and a casing 31. The cylindrical housing 15 and the second hollow shaft 23 are connected at an inner diameter side of one bearing 33. The first hollow shaft 11 is supported via a third bearing 45 and a fourth bearing. Driving force inputted into one end side of the first hollow shaft 11 is transmitted from an intermediate part between the third bearing 45 and the fourth bearing 47 on the other end side of the first hollow shaft 11 via the inside clutch plate 13 and the outside clutch plate 17, the cylindrical housing 15, a first side wall 37, a first boss part 38, the second hollow shaft 23 and a pair of gears 27. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a power transmission device used for an on-demand 4WD vehicle.

  Conventionally, as a power transmission device used in an on-demand 4WD vehicle, a second differential drive case that drives left and right auxiliary drive wheels by a first differential case that drives left and right main drive wheels driven from a drive source. One in which driving force is distributed to the differential side is known (for example, see Patent Document 1).

  This power transmission device is coaxial with one outer periphery of a pair of wheel drive shafts connected to the output side of the first differential in order to transmit the distributed driving force to the second differential side on the sub drive wheel side. Driving force transmitted between the first hollow shaft disposed on the outer periphery, the second hollow shaft disposed on the outer peripheral side of the first hollow shaft, and the first hollow shaft and the second hollow shaft. Is provided with a power transmission mechanism including a clutch mechanism capable of controlling the rotation of the second hollow shaft by a magnetic force of the electromagnet and a bevel gear type gear set for changing the direction of driving rotation of the second hollow shaft and transmitting it to the second differential side. The power transmission mechanism is housed in a second casing that is fixed to the first casing that houses the first differential, and forms a power transmission device.

  According to such a power transmission device, the driving force transmitted to the second differential side is controlled by controlling the fastening force of the clutch mechanism. When the clutch mechanism is disengaged, the driving force is transmitted only to the first differential, so that the vehicle can travel in a so-called 2WD state, and the traveling fuel consumption of the vehicle can be improved. On the other hand, by intermediately controlling the engaging force of the clutch mechanism, the driving force can be accurately distributed and transmitted to the second differential side, so that the vehicle can run in a so-called 4WD state, and the vehicle can start and turn. Travel stability can be improved. A vehicle equipped with such a power transmission device is generally called an on-demand 4WD vehicle.

JP-A-4-372427

  However, in the power transmission device as in Patent Document 1, the power transmission mechanism is housed in the second casing and is fixed to the first casing, thereby improving the mountability as a drive system. Is disposed between the gear set and the clutch plate of the clutch mechanism in one wheel drive shaft direction, and the first hollow shaft becomes longer and the support becomes unstable. As a result, there is a problem that it is easy to increase in size and increases in weight.

  Accordingly, an object of the present invention is to provide a power transmission device used in an on-demand type 4WD vehicle that can be reduced in size and improved in supportability.

  According to the first aspect of the present invention, the first hollow is coaxially disposed on one outer periphery of a pair of wheel drive shafts connected to the output side of the first differential, and one end side is connected to the differential case of the first differential. A shaft, a plurality of inner clutch plates engaged with the other end of the first hollow shaft in the rotational direction, a plurality of outer clutch plates engaged with the inner periphery of the cylindrical housing in the rotational direction, and the inner side A clutch mechanism comprising an actuator that engages and engages the clutch plate and the outer clutch plate in the axial direction, and is connected to one end side of the cylindrical housing and rotates on the outer peripheral side of the first hollow shaft A second hollow shaft arranged in a possible manner, an output gear fixed to the outer periphery of the second hollow shaft, a transmission gear that meshes with the output gear and forms a gear set, and the first gear. Hollow shaft, clutch mechanism, and second hollow And a power transmission device used in an on-demand type 4WD vehicle including a casing that accommodates the output gear and the transmission gear, wherein the second hollow shaft is connected to both ends via a pair of bearings. The cylindrical housing of the clutch mechanism, supported by the casing, integrally has a first side wall on one end side, and a first boss portion extending from the inner diameter side of the first side wall One of the pair of bearings is connected to the second hollow shaft on the inner diameter side of one of the bearings, and integrally has a second side wall on the other end side, and the second boss extends from the inner diameter side of the second side wall. And the actuator is disposed on the opposite side of the inner clutch plate and the outer clutch plate with the second side wall sandwiched in the axial direction, and the first hollow shaft is disposed on the first hollow shaft. The second boss portion is supported by the boss portion via a third bearing. The outer periphery of the second boss portion is supported by the casing via a fifth bearing, and the driving force input to one end side of the first hollow shaft is From the intermediate portion between the third bearing and the fourth bearing on the other end side of the first hollow shaft, the inner clutch plate, the outer clutch plate, the cylindrical housing, and the first side wall The first boss portion, the second hollow shaft, and the gear set are transmitted.

  The invention according to claim 2 is the power transmission device according to claim 1, wherein the actuator of the clutch mechanism includes an electromagnet supported with respect to the casing, and the electromagnet disposed in the cylindrical housing. An armature that is attracted by a magnetic force that passes through the second side wall when excited, and a pilot clutch that is disposed between the armature and the second side wall in the cylindrical housing and is pressed and fastened; A cam mechanism that converts an engaging force of the pilot clutch into an axial thrust, and a pressing member that applies a pressing force to the inner clutch plate and the outer clutch plate by the thrust of the cam mechanism. And

  The invention according to claim 3 is the power transmission device according to claim 1 or 2, wherein the gear set includes a ring gear fixed to the outer periphery of the second hollow shaft, and orthogonal to the second hollow shaft. A bevel gear set comprising a pinion that meshes with the ring gear, wherein the other bearing of the pair of bearings that support the second hollow shaft is opposed to the tip of the pinion.

  Invention of Claim 4 is the power transmission device of any one of Claim 1 thru | or 3, Comprising: One of the said wheel drive shafts are between the internal peripheral surfaces of a said 1st hollow shaft. A predetermined gap is secured, and the end side is supported by the inner periphery of the second boss portion via a sixth bearing, and the sixth bearing overlaps the fifth bearing in the radial direction. It is characterized by being.

  In the power transmission device according to the first aspect, since the actuator is arranged on the second side wall side, the length of the first hollow shaft corresponding to the actuator arrangement is shortened, so that the space and the weight are reduced accordingly. be able to. In addition, since the connecting portion between the first boss portion and the second hollow shaft is provided on the inner diameter side of the bearing, the length of the second hollow shaft can be shortened.

  Further, since the actuator is disposed on the second side wall side, the cylindrical housing, the first side wall, and the first boss portion as the driving force transmission path are selected as materials suitable for the driving path. Can do. For this reason, arrangement | positioning space can be made compact using the member which considered appropriate intensity | strength, a shape, and weight.

  Further, since the first hollow shaft is supported by the first boss portion and the second boss portion at both side portions of the inner clutch plate and the outer clutch plate, the shaft runout on the end portion side of the first hollow shaft is supported. The driving force can be stably transmitted from the first hollow shaft to the inner clutch plate and the outer clutch plate.

  Therefore, size reduction and supportability can be improved.

  In the power transmission device according to claim 2, the second side wall does not transmit the driving force so that the second side wall transmits magnetic force, and the second boss portion is supported by the fifth bearing. Since the selected material can be selected, the arrangement space can be made compact.

  The electromagnet can be supported with respect to the casing, and the pilot clutch, the cam mechanism, and the pressing member are disposed in the cylindrical housing, and the outer periphery of the first hollow shaft is between the third bearing and the fourth bearing. Therefore, the supportability is improved and the operation characteristics of the actuator are stabilized.

  In the power transmission device according to the third aspect, the other end of the bearing that supports the second hollow shaft is disposed opposite to the tip of the pinion, so that the second hollow is not secured in the axial direction alone. The shaft and casing can be reduced in size and weight.

  In the power transmission device according to the fourth aspect, since the fifth bearing and the sixth bearing are overlapped in the radial direction, the axial direction can be reduced. In addition, since one end of the wheel drive shaft is supported on the end side, the shaft runout of the wheel drive shaft can be suppressed.

It is the schematic which shows the motive power system of a vehicle. It is sectional drawing of the power transmission device which concerns on embodiment of this invention.

  First, an example of a vehicle power system to which a power transmission device according to an embodiment of the present invention is applied will be described with reference to FIG.

  As shown in FIG. 1, the power system of the vehicle includes a drive source such as an engine 201 and an electric motor 203, a transmission 205 as a speed change mechanism, and a first differential 3 that allows differential between the left and right wheels on the front wheel side. The front axles 207 and 209, the front wheels 211 and 213, the power transmission device 1, the propeller shaft 215, the rear differential 217 as a second differential allowing the differential of the left and right wheels on the rear wheel side, and the rear axle 219 , 221 and rear wheels 223, 225 and the like. In the vicinity of the transmission 205, an electric motor 227 for shifting and driving is connected to the transmission 205.

  The driving force of the driving source is transmitted from the transmission 205 to the pinion 63 via the differential case 9 of the first differential 3 supported and arranged in the transmission case 229, and is connected to the pair of side gears 65 and 67 by the front axles 207 and 209. Are distributed to the front wheels 211 and 213, branched to the first hollow shaft 11 connected to the differential case 9, and transmitted to the power transmission device 1. The driving force transmitted to the power transmission device 1 is a clutch mechanism disposed between the first hollow shaft 11 and the second hollow shaft 23 disposed so as to be rotatable relative to the first hollow shaft 11. 21 is transmitted.

  When the inner clutch plate 13 and the outer clutch plate 17 are connected in a controllable manner by the actuator 19, the driving force transmitted to the clutch mechanism 21 is transmitted from the gear set 27 including the output gear 25 and the transmission gear 29 to the propeller shaft. 215 is transmitted to the rear differential 217, and is distributed from the rear axles 219 and 221 to the rear wheels 223 and 225 to be in a four-wheel drive state of front and rear wheel drive. Further, when the connection between the inner clutch plate 13 and the outer clutch plate 17 is released, the vehicle enters a two-wheel drive state of front wheel drive. Hereinafter, the power transmission device will be described.

  A power transmission device according to an embodiment of the present invention will be described with reference to FIGS.

  The power transmission device 1 according to the present embodiment is coaxially disposed on the outer periphery of a wheel drive shaft 7 as one of a pair of wheel drive shafts 5, 7 connected to the output side of the first differential 3. A first hollow shaft 11 having one axial end connected to the differential case 9 of the differential 3, and a plurality of inner clutch plates 13 engaged in the rotational direction with the other axial end of the first hollow shaft 11. A clutch comprising a plurality of outer clutch plates 17 engaged with the inner periphery of the cylindrical housing 15 in the rotational direction, and an actuator 19 that engages the inner clutch plates 13 and the outer clutch plates 17 in the axial direction. A mechanism 21 is connected to one end side of the cylindrical housing 15, and the second hollow shaft 23 is rotatably arranged on the outer peripheral side of the first hollow shaft 11, and the outer periphery of the second hollow shaft 23 And an output gear 25 fixed to the output gear 2 The transmission gear 29 that forms a gear set 27 together with the output gear 25 so as to transmit the driving force, and the first hollow shaft 11, the clutch mechanism 21, the second hollow shaft 23, the output gear 25, and the transmission gear 29. The housing 31 is housed and used for an on-demand 4WD vehicle.

  The second hollow shaft 23 is supported by the casing 31 on both ends in the axial direction of the output gear 25 via a pair of bearings 33 and 35, and the cylindrical housing 15 of the clutch mechanism 21 is connected to the first end on the one end side. The first boss portion 39 extending integrally from the inner diameter side of the first side wall 37 has a second side wall 37 on the inner diameter side of one of the pair of bearings 33, 35. The second side wall 41 is integrally connected to the hollow shaft 23 on the other end side, a second boss portion 43 is extended from the inner diameter side of the second side wall 41, and the actuator 19 The first hollow shaft 11 is supported by the first boss portion 39 via a third bearing 45 with the side wall 41 sandwiched in the axial direction on the opposite side of the inner clutch plate 13 and the outer clutch plate 17. In addition, the second boss portion 43 is supported by the fourth bearing 47 through the fourth bearing 47. The outer periphery of the first hollow shaft 11 is supported by the casing 31 via a fifth bearing 49, and the driving force input to one end side of the first hollow shaft 11 is the third bearing 45 on the other end side of the first hollow shaft 11. And the fourth clutch 47 from the axial intermediate portion, the inner clutch plate 13, the outer clutch plate 17, the cylindrical housing 15, the first side wall 37, the first boss portion 39, and the second It is transmitted via the hollow shaft 23 and the gear set 27.

  Further, the actuator 19 of the clutch mechanism 21 is attracted by an electromagnet 51 supported with respect to the casing 31 and a magnetic force that is disposed in the cylindrical housing 15 and passes through the second side wall 41 when the electromagnet 51 is excited. Armature 53, a pilot clutch 55 disposed between the armature 53 and the second side wall 41 in the cylindrical housing 15 and pressed and fastened, and the fastening force of the pilot clutch 55 is converted into axial thrust. And a pressing member 59 that applies a pressing force to the inner clutch plate 13 and the outer clutch plate 17 by the thrust of the cam mechanism 57.

  Further, the gear set 27 is a bevel gear set including a ring gear fixed to the outer periphery of the second hollow shaft 23 and a pinion that is orthogonal to the second hollow shaft 23 and meshes with the ring gear. Of the pair of bearings 33 and 35 that support the hollow shaft 23, the other bearing 35 is disposed oppositely.

  Further, the wheel drive shaft 7 has a predetermined clearance between the inner peripheral surface of the first hollow shaft 11, one end portion in the axial direction is connected to the differential case 9, and the other end portion in the axial direction is connected to the sixth end. The sixth bearing 61 is supported on the inner periphery of the second boss portion 43 via the bearing 61 and overlaps with the fifth bearing 49 in the radial direction.

  As shown in FIGS. 1 and 2, the first differential 3 includes a differential case 9, a pinion 63, and a pair of side gears 65 and 67. The differential case 9 is rotatably supported with respect to the transmission case 229, and the driving force from the driving source is transmitted via the transmission 205. The differential case 9 accommodates a pinion 63 and a pair of side gears 65 and 67.

  The pinion 63 is supported by a pinion shaft that rotates integrally with the differential case 9 and revolves as the differential case 9 rotates. Further, the pinion 63 transmits a driving force to the pair of side gears 65 and 67 and is rotatably supported on the pinion shaft so as to be rotated when a differential rotation occurs between the pair of side gears 65 and 67 engaged with each other. Yes.

  The pair of side gears 65 and 67 are supported by the differential case 9 so as to be relatively rotatable, and mesh with the pinion 63. A pair of wheel drive shafts 5 and 7 connected to the front wheels 211 and 213 of the vehicle are connected to the pair of side gears 65 and 67 so as to be integrally rotatable, and transmit driving force to the left and right wheels. A first hollow shaft 11 is coaxially disposed on the outer periphery of one of the pair of wheel drive shafts 5 and 7.

  The first hollow shaft 11 is formed in a hollow shape, and the wheel drive shaft 7 is inserted on the inner peripheral side so as to be relatively rotatable. In addition, a spline-shaped connecting portion 69 that is connected to the differential case 9 of the first differential 3 so as to be integrally rotatable is provided on the outer periphery on one axial end side of the first hollow shaft 11. A plurality of inner clutch plates 13 of the clutch mechanism 21 are engaged with the first hollow shaft 11 in the rotational direction so as to rotate together with the first hollow shaft 11 on the outer periphery on the other end side in the axial direction of the first hollow shaft 11. The driving force input from the third side is transmitted to the clutch mechanism 21 via the first hollow shaft 11.

  The clutch mechanism 21 includes a plurality of inner clutch plates 13, a plurality of outer clutch plates 17, a cylindrical housing 15, and an actuator 19. The plurality of inner clutch plates 13 are engaged with an engagement portion 71 formed on the outer periphery of the first hollow shaft 11 so as to be axially movable and integrally rotatable with the first hollow shaft 11. The plurality of outer clutch plates 17 are alternately arranged in the axial direction with respect to the plurality of inner clutch plates 13, and can be moved in the axial direction to an engagement portion 73 formed on the inner periphery of the cylindrical housing 15. The housing 15 is engaged with the housing 15 so as to be integrally rotatable. The multi-plate clutch composed of the inner clutch plate 13 and the outer clutch plate 17 is a control type friction clutch capable of intermediate control of transmission torque with sliding friction.

  The cylindrical housing 15 is disposed on the outer peripheral side of the first hollow shaft 11 so as to be rotatable relative to the first hollow shaft 11, and includes a first side wall 37 and a second side wall 41. The first side wall 37 is integrally formed as one member continuous with the cylindrical portion on one axial end side of the cylindrical portion, and a first boss portion 39 is extended in the axial direction on the inner diameter side. The second side wall 41 is made of a magnetic material, and a screw-shaped connecting portion 75 connected to the inner periphery on the other axial end side of the cylindrical portion is formed on the outer peripheral side. A nut 77 is screwed to the connecting portion 75 and is more firmly fixed so as to be integrally rotatable by a double nut function of the connecting portion 75 and the nut 77. A second boss portion 43 extends in the axial direction on the inner diameter side of the second side wall 41. An actuator 19 is disposed on the opposite side of the inner clutch plate 13 and the outer clutch plate 17 with the second side wall 41 sandwiched in the axial direction.

  The actuator 19 includes an electromagnet 51, an armature 53, a pilot clutch 55, a cam mechanism 57, and a pressing member 59 including the second side wall 41.

  The electromagnet 51 includes an electromagnetic coil 79 and a core 81, and is prevented from rotating by a rotation preventing member 83 with respect to the casing 31 that is a stationary system member. The core 81 is connected to a controller (not shown) for controlling energization via a lead wire 85, and electromagnetically generated so as to generate necessary friction torque between the inner clutch plate 13 and the outer clutch plate 17 by the control of the controller. The coil 79 is energized. The armature 53 is attracted and moved by the excitation of the electromagnet 51.

  The armature 53 is made of a magnetic material, is axially movable in the cylindrical housing 15, and is disposed opposite to the second side wall 41 with the pilot clutch 55 interposed therebetween in the axial direction. When the electromagnet 51 is excited, the armature 53 is attracted and moved to the electromagnet 51 side by a magnetic flux loop formed by circulating magnetic lines of force through the core 81, the second side wall 41, the pilot clutch 55, and the armature 53, The pilot clutch 55 is connected.

  The pilot clutch 55 is disposed in the cylindrical housing 15 between the second side wall 41 and the armature 53 in the axial direction, and is movable in the axial direction to the engaging portion 73 of the cylindrical housing 15. And a plurality of inner plates that are arranged alternately on the outer periphery of the cam ring 87 in the axial direction with respect to the outer plates and that can move in the axial direction and are connected to the cam ring 87 so as to be integrally rotatable. It consists of and. The engagement torque of the pilot clutch 55 is converted into an axial thrust through the cam mechanism 57, and a predetermined drive torque is transmitted by pressing the inner clutch plate 13 and the outer clutch plate 17 by the pressing member 59.

  The cam mechanism 57 includes a cam ball 89 interposed between the cam ring 87 and the pressing member 59 facing the cam surface formed in the circumferential direction. The cam ring 87 is disposed on the outer periphery of the first hollow shaft 11 on the other end side in the axial direction so as to be movable in the axial direction, and the inner plate of the pilot clutch 55 is coupled so as to be integrally rotatable. A thrust bearing 91 that receives a thrust reaction force generated by the cam mechanism 57 is disposed between the cam ring 87 and the second side wall 41 in the axial direction.

  The cam ball 89 is disposed between the cam surfaces formed on the cam ring 87 and the pressing member 59. This cam ball 89 causes the pressing member 59 and the inner clutch plate 13 to have a strength corresponding to the friction torque generated in the pilot clutch 55 when a differential rotation occurs between the cam ring 87 and the pressing member 59 due to the connection of the pilot clutch 55. A cam thrust force is generated for axially pressing and moving toward the outer clutch plate 17 side.

  The pressing member 59 is engaged with the engaging portion 71 of the first hollow shaft 11 so as to be axially movable and integrally rotatable with the first hollow shaft 11. The pressing member 59 is axially moved toward the inner clutch plate 13 and the outer clutch plate 17 by a thrust force generated by the cam mechanism 57, and applies a pressing force to the inner clutch plate 13 and the outer clutch plate 17 to connect them. The first hollow shaft 11 and the cylindrical housing 15 are connected. Thus, the second hollow shaft 23 is coupled to the cylindrical housing 15 connected to the first hollow shaft 11 by the connection between the inner clutch plate 13 and the outer clutch plate 17 so as to be integrally rotatable.

  The second hollow shaft 23 is formed in a hollow shape, and rotates integrally with the cylindrical housing 15 by a spline-shaped connecting portion 93 formed on the outer periphery of the first boss portion 39 of the cylindrical housing 15. Connected as possible. An output gear 25 is fixed to the outer periphery of the second hollow shaft 23 so as to rotate together with the second hollow shaft 23.

  The output gear 25 is a ring gear and is fixed to the outer periphery of the second hollow shaft 23 by fixing means such as welding. The output gear 25 meshes with the transmission gear 29 to form a gear set 27 that transmits driving force.

  The transmission gear 29 is a pinion, and the gear set 27 that meshes with the output gear 25 is a bevel gear set. Specifically, the gear set 27 is a bevel gear type hypoid gear set. The transmission gear 29 is formed as a continuous member with a power transmission shaft 95.

  The power transmission shaft 95 is rotatably supported by the casing 31 via bearings 97 and 99, and the propeller shaft 215 is coupled to the flange member 101 coupled to the power transmission shaft 95 so as to be integrally rotatable. The driving force from the source is transmitted. The driving force transmitted to the power transmission shaft 95 is transmitted to the rear differential 217 side as the second differential via the propeller shaft 215.

  The casing 31 that accommodates each member is integrally fixed by three fixing members such as bolts 103 and 105, and is divided into a transmission-side casing or a body frame as a stationary member. Fixed. Each member accommodated in the casing 31 is rotatably supported via a bearing, and each bearing is arranged in consideration of power transmission and downsizing of the apparatus.

  The pair of bearings 33 and 35 are tapered roller bearings, and support both ends of the second hollow shaft 23 so as to be rotatable with respect to the casing 31. A connecting portion 93 between the cylindrical housing 15 and the second hollow shaft 23 is disposed so as to overlap in the radial direction on the inner diameter side of one of the pair of bearings 33 and 35. The other bearing 35 of the pair of bearings 33 and 35 is disposed to face the tip of the pinion that is the transmission gear 29. By arranging the pair of bearings 33 and 35 in this way, the axial span of the pair of bearings 33 and 35 can be shortened, and the second hollow shaft 23 can be shortened and the casing 31 can be downsized. it can. Note that an inexpensive ball bearing can be used as the pair of bearings 33 and 35 if the driving torque and the meshing force of the gear set are allowed.

  The third bearing 45 is composed of a ball bearing, and the first hollow shaft 11 is disposed between the radial direction between the outer periphery of the intermediate portion of the first hollow shaft 11 and the inner periphery of the first boss portion 39 of the cylindrical housing 15. It is supported so as to be rotatable relative to the cylindrical housing 15. The fourth bearing 47 is formed of a sliding bush, and the first bearing is disposed between the outer circumference of the first hollow shaft 11 on the other end side in the axial direction and the inner circumference of the second boss portion 43 of the cylindrical housing 15. The hollow shaft 11 is supported so as to be rotatable relative to the cylindrical housing 15. By disposing the third bearing 45 and the fourth bearing 47 in this way, the first hollow shaft 11 is connected to the first boss portion 39 and the second at both side portions of the inner clutch plate 13 and the outer clutch plate 17. The boss 43 is supported by the bearing, and the shaft center shake on the end side of the first hollow shaft 11 can be suppressed.

  The fifth bearing 49 is formed of a ball bearing, and the cylindrical housing 15 is disposed between the outer periphery of the second boss 43 of the cylindrical housing 15 and the inner periphery of the core 81 of the electromagnet 51 with respect to the casing 31. It is rotatably supported. The sixth bearing 61 rotates the wheel drive shaft 7 relative to the cylindrical housing 15 between the radial direction between the outer periphery of the end of the wheel drive shaft 7 and the inner periphery of the second boss portion 43 of the cylindrical housing 15. I support it as possible. The core 81 of the electromagnet 51 is supported in the radial direction with respect to the casing 31, supported in one axial direction, and supported in the rotational direction, and becomes a stationary member in the same manner as the casing 31. However, as another example, the second boss portion 43 may be directly supported on the casing 31 via the fifth bearing 49. In addition, the wheel drive shaft 7 is provided with a predetermined gap between the wheel drive shaft 7 and the inner peripheral surface of the first hollow shaft 11, and is disposed so as to be relatively rotatable with the first hollow shaft 11. The sixth bearing 61 is disposed so as to overlap the fifth bearing 49 in the radial direction. By disposing the fifth bearing 49 and the sixth bearing 61 in this way, the axial direction can be reduced, and the axial runout of the wheel drive shaft 7 can be suppressed.

  In the power transmission device 1 configured as described above, the armature 53 is attracted and moved by energization control to the electromagnet 51, presses the pilot clutch 55, and the pilot clutch 55 is connected with controlled friction torque. When the pilot clutch 55 is connected, a cam thrust force is generated by the cam mechanism 57 and the pressing member 59 is pressed and moved toward the inner clutch plate 13 and the outer clutch plate 17. By the movement of the pressing member 59, the inner clutch plate 13 and the outer clutch plate 17 are connected, and the first hollow shaft 11 and the cylindrical housing 15 are connected. Due to the connection between the first hollow shaft 11 and the cylindrical housing 15, the driving force is transmitted from the first differential 3 side to the rear differential 217 side via the gear set 27, and the necessary driving force is transmitted to the rear wheel side. The vehicle is in a four-wheel drive state with front and rear wheel drive so that transmission is possible.

  In such a transmission path for transmitting power from the first differential 3 side to the rear differential 217 side of the power transmission device 1, the driving force input to one end side of the first hollow shaft 11, that is, the first differential 3 side. The driving force input to the first hollow shaft 11 from the middle portion of the third bearing 45 and the fourth bearing 47 on the other end side of the first hollow shaft 11 from the inner clutch plate 13 and the outer clutch plate 17. Are transmitted through the cylindrical housing 15, the first side wall 37, the first boss portion 39, the second hollow shaft 23, and the gear set 27, and output to the rear differential 217 side. On the transmission path, the second side wall 41 made of a magnetic material that transmits the magnetic flux of the electromagnet 51 is not disposed. Therefore, the setting of the magnetic path of the actuator 19 can be made independent from the power transmission, and the second side wall 41 is selected as a material suitable for magnetic path formation, or the cylindrical housing 15 and the first side wall 37 The degree of freedom in setting magnetic path formation and power transmission can be improved by selecting the first boss portion 39 as a material suitable for the drive path.

  In such a power transmission device 1, since the actuator 19 is arranged on the second side wall 41 side, the length of the first hollow shaft 11 corresponding to the arrangement of the actuator 19 is shortened. Weight can be reduced. Moreover, since the connection part 93 of the 1st boss | hub part 39 and the 2nd hollow shaft 23 was provided in the internal diameter side of the bearing 33, the length of the 2nd hollow shaft 23 can be shortened.

  Further, since the actuator 19 is arranged on the second side wall 41 side, the cylindrical housing 15 as the driving force transmission path, the first side wall 37 and the first boss portion 39 are suitable for the driving path. The material can be selected. For this reason, arrangement | positioning space can be made compact using the member which considered appropriate intensity | strength, a shape, and weight.

  Further, since the first hollow shaft 11 is supported by the first boss portion 39 and the second boss portion 43 at both sides of the inner clutch plate 13 and the outer clutch plate 17, the end of the first hollow shaft 11 is It is possible to suppress the shaft center shake on the part side and stably transmit the driving force from the first hollow shaft 11 to the inner clutch plate 13 and the outer clutch plate 17.

  Therefore, size reduction and supportability can be improved.

  In addition, the second side wall 41 does not transmit the driving force, thereby transmitting the magnetic force to the second side wall 41, and a material that takes into consideration the support strength with which the second boss portion 43 is supported by the fifth bearing 49. Since it can be selected, the arrangement space can be made compact.

  Further, the electromagnet 51 can be supported with respect to the casing 31, and the pilot clutch 55, the cam mechanism 57, and the pressing member 59 are disposed in the cylindrical housing 15, and are arranged between the third bearing 45 and the fourth bearing 47. Thus, since the outer periphery of the first hollow shaft 11 is accurately supported, the supportability is improved and the operation characteristics of the actuator 19 are stabilized.

  In addition, since the bearing 35 that supports the second hollow shaft 23 is disposed opposite to the tip of the pinion that is the transmission gear 29, the bearing space is not secured independently in the axial direction, and the second hollow shaft 23 is not secured. In addition, the casing 31 can be reduced in size and weight.

  Furthermore, since the fifth bearing 49 and the sixth bearing 61 are overlapped in the radial direction, the axial direction can be reduced. Further, since the wheel drive shaft 7 is supported on the end side, the shaft center shake of the wheel drive shaft 7 can be suppressed.

  In the power transmission device according to the embodiment of the present invention, the mechanism that inputs the driving force to the first hollow shaft is a differential mechanism that allows the differential of the left and right wheels on the front wheel side, but is not limited thereto. Any mechanism such as a differential mechanism that allows differential between the front and rear wheels may be used.

  In addition, as a definition of the phrase, “integral” is not limited to a continuous shape made of one material, but a plurality of materials are integrally operated by using a connecting means such as welding, bonding, or bolting. Including those formed.

  Further, the “gear set” is not limited to the hypoid gear set described in the embodiment, and may be configured in multiple stages using a plurality of transmission gears 29 arranged on the output gear 25 and subsequent stages. Good. In this case, the gear set is arranged in the casing 31.

DESCRIPTION OF SYMBOLS 1 ... Power transmission device 3 ... 1st differential 5, 7 ... Wheel drive shaft 9 ... Differential case 11 ... 1st hollow shaft 13 ... Inner clutch plate 15 ... Cylindrical housing 17 ... Outer clutch plate 19 ... Actuator 21 ... Clutch Mechanism 23 ... Second hollow shaft 25 ... Output gear 27 ... Gear set 29 ... Transmission gear 31 ... Casing 33, 35 ... Pair of bearings 37 ... First side wall 39 ... First boss portion 41 ... Second side wall 43 ... Second boss 45 ... Third bearing 47 ... Fourth bearing 49 ... Fifth bearing 51 ... Electromagnet 53 ... Armature 55 ... Pilot clutch 57 ... Cam mechanism 59 ... Pressing member 61 ... Sixth bearing

Claims (4)

A first hollow shaft coaxially disposed on one outer periphery of a pair of wheel drive shafts connected to the output side of the first differential and having one end connected to the differential case of the first differential, and the first hollow A plurality of inner clutch plates engaged in the rotational direction with the other end of the shaft; a plurality of outer clutch plates engaged in the rotational direction on the inner periphery of the cylindrical housing; the inner clutch plates and the outer clutch plates; And a clutch mechanism comprising an actuator that engages and engages in the axial direction, and a second mechanism that is coupled to one end of the cylindrical housing and is rotatably disposed on the outer peripheral side of the first hollow shaft. A hollow shaft; an output gear fixed to the outer periphery of the second hollow shaft; a transmission gear that meshes with the output gear and transmits a driving force; the first hollow shaft; the clutch mechanism; A second hollow shaft, the output gear, and the The power transmission device used in an on-demand type 4WD vehicle having a casing housing the reach gear,
The second hollow shaft is supported at both ends by the casing via a pair of bearings, and the cylindrical housing of the clutch mechanism integrally has a first side wall at one end, A first boss portion extending from the inner diameter side of the first side wall is connected to the second hollow shaft on the inner diameter side of one of the pair of bearings, and the second side wall is integrated with the other end side. And the second boss portion extends from the inner diameter side of the second side wall, and the actuator is opposite to the inner clutch plate and the outer clutch plate across the second side wall in the axial direction. The first hollow shaft is supported on the first boss portion via a third bearing and supported on the second boss portion via a fourth bearing, The outer periphery of the second boss portion is supported by the casing via a fifth bearing,
The driving force input to one end side of the first hollow shaft is transmitted from the intermediate portion between the third bearing and the fourth bearing on the other end side of the first hollow shaft to the inner clutch plate and the outer side. Power is transmitted through a clutch plate, the cylindrical housing, the first side wall, the first boss, the second hollow shaft, and the gear set. Transmission device. The power transmission device according to claim 1,
The actuator of the clutch mechanism includes an electromagnet supported with respect to the casing, an armature that is disposed in the cylindrical housing and is attracted by a magnetic force that passes through the second side wall when the electromagnet is excited, A pilot clutch disposed between the armature and the second side wall in the cylindrical housing and pressed and fastened, a cam mechanism for converting the fastening force of the pilot clutch into an axial thrust, and the cam A power transmission device comprising: a pressing member that applies a pressing force to the inner clutch plate and the outer clutch plate by a thrust of a mechanism. The power transmission device according to claim 1 or 2,
The gear set is a bevel gear set including a ring gear fixed to the outer periphery of the second hollow shaft and a pinion that is perpendicular to the second hollow shaft and meshes with the ring gear. 2. The power transmission device according to claim 1, wherein the other bearing of the pair of bearings supporting the two hollow shafts is disposed opposite to the other. The power transmission device according to any one of claims 1 to 3,
A predetermined gap is secured between one of the wheel drive shafts and the inner peripheral surface of the first hollow shaft, and the end side is connected to the inner periphery of the second boss portion via a sixth bearing. The power transmission device is characterized in that the sixth bearing is radially overlapped with the fifth bearing.

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