JP2012224229A - Power transmission device for four-wheel drive vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power transmission device for a four-wheel drive vehicle that can reduce drag torque while improving torque transmission responsiveness toward secondary drive wheels side.SOLUTION: The power transmission device 100 positioned between a propeller shaft 16 at a front wheels 14 side and a drive pinion shaft 21 at a rear wheels 19 side includes: a coupling unit 110 that can be switched between an engagement state where torque input from the propeller shaft 16 is transmitted to the drive pinion shaft 21 due to engagement torque of a multiplate wet clutch and a release state where the torque is not transmitted; a diff-lock unit 120 that can be switched between a connected state where the propeller shaft 16 is connected directly with the drive pinion shaft 21 and a non-connected state where the torque is not transmitted wherein a common actuator 130 performs switching between the engagement state and the release state at the coupling unit 110, and between the connected state and the non-connected state at the diff-lock unit 120.

Description

  The present invention relates to a power transmission device for a four-wheel drive vehicle.

  As a power transmission device for a four-wheel drive vehicle, an apparatus disposed between an input shaft provided on the main drive wheel side and an output shaft provided on the sub drive wheel side is known. In such a power transmission device, the two-wheel drive state in which the torque from the drive source is not transmitted to the auxiliary drive wheel but only to the main drive wheel, and the torque from the drive source is transmitted to both the main drive wheel and the auxiliary drive wheel. The four-wheel drive state is switched.

  For example, there is an electronically controlled coupling having a wet multi-plate clutch as a power transmission device used in a four-wheel drive vehicle based on a front wheel drive. However, if the electronically controlled coupling is simply disposed between the input shaft on the main drive wheel side (front wheel side) and the output shaft on the sub drive wheel side (rear wheel side), the following problems are concerned. . Drag torque due to the viscous resistance of oil between the friction plates of the wet multi-plate clutch is generated, and there is a concern about loss due to drag torque. In the hybrid vehicle, torque is transmitted to the rear wheel side by the drag torque at the time of regenerative braking, so that there is a problem that regenerative energy on the front wheel side is reduced. Furthermore, if the number of friction plates of the wet multi-plate clutch is increased in order to secure the torque capacity to the rear wheel side, there is a problem that the drag torque is increased. In addition, when the vehicle is towed (so-called two-wheel towed) with only the rear wheels in contact with the ground when the engine is stopped, a large rotational speed difference occurs between the input shaft and the output shaft. There is also concern that the calorific value will increase.

  Conventionally, there has been proposed an electronically controlled coupling provided with a biasing member that biases a friction plate of a wet multi-plate clutch in a connection release direction (see, for example, Patent Document 1). According to this electronically controlled coupling, the loss due to the drag torque as described above can be reduced, and the amount of heat generated by the wet multi-plate clutch can be reduced when the two-wheel is towed.

  It is also known as a four-wheel drive vehicle that switches between a two-wheel drive state and a four-wheel drive state by driving front wheels with a drive source including an engine, an electric motor, etc., and driving rear wheels with an electric motor as required. However, there are the following problems. In other words, in the case of an electric motor, the output torque is smaller than that of an engine, so that the four-wheel drive performance when climbing or escaping from a stack is higher than that of a four-wheel drive vehicle that transmits engine torque and drives the rear wheels. There is a problem of being inferior. In addition, there is a problem that the battery may be overcharged as a result of power generation by the motor when the two-wheel is towed as described above.

JP 2009-257558 A

  By the way, in the electronically controlled coupling described in Patent Document 1, the following problem may occur due to the provision of the biasing member in the wet multi-plate clutch.

  That is, since it is necessary to engage the friction plates of the wet multi-plate clutch against the urging force of the urging member, the transmission torque rises to the auxiliary driving wheel side (rear wheel side) in the four-wheel drive state. Response delay may occur. In addition, when starting the vehicle while the vehicle is stopped on an uphill road (when starting up an uphill road), there is a possibility that a phenomenon in which the vehicle moves backward against the driver's intention (so-called sliding phenomenon) may occur. is there.

  The present invention has been made in view of such problems, and is a four-wheel drive capable of improving the torque transmission response to the auxiliary drive wheel side while reducing the drag torque of the wet multi-plate clutch. It aims at providing the power transmission device of a car.

  In the present invention, means for solving the above-described problems are configured as follows. That is, the present invention transmits the torque from the drive source to only the main drive wheel without transmitting it to the sub drive wheel, and transmits the torque from the drive source to both the main drive wheel and the sub drive wheel. A power transmission device for a four-wheel drive vehicle configured to be switchable between four-wheel drive states, comprising: an input shaft provided on the main drive wheel side; and an output shaft provided on the sub drive wheel side It is arranged between the engagement state in which the torque input from the input shaft is transmitted to the output shaft according to the engagement torque of the wet multi-plate clutch and the release state in which torque transmission is not performed. A coupling portion, and a differential lock portion configured to be able to switch between a connection state in which the input shaft and the output shaft are directly connected and a non-connection state in which torque transmission is not performed, and the engagement state of the coupling portion And switching to the released state, and Switching between the connected state and the non-connected state of the differential lock portion, and characterized by being performed by a common actuator. In this case, the first four-wheel drive state in which the coupling portion is in an engaged state and the differential lock portion is in a disconnected state, the coupling portion is in a released state, and the differential lock portion is in a connected state. It is preferable that the second four-wheel drive state and a two-wheel drive state in which the coupling portion is in a released state and the differential lock portion is in a disconnected state are switched by the actuator.

  According to the power transmission device for a four-wheel drive vehicle having the above-described configuration, the common actuator switches between the engaged state and the released state of the coupling portion and the connected state and the unconnected state of the differential lock portion. Therefore, the configuration can be simplified.

  Further, it is possible to improve the torque transmission responsiveness to the auxiliary drive wheel side while reducing the drag torque of the wet multi-plate clutch of the coupling portion. This point will be described in detail. In the second four-wheel drive state, the input shaft and the output shaft are directly connected by switching the differential lock portion to the connected state, so that the torque required for the auxiliary drive wheel can be easily secured, It is possible to improve the four-wheel drive performance when escaping from the time or from the stack. And the torque transmission responsiveness to the sub drive wheel side can be improved, and the phenomenon of the sliding down at the time of starting uphill road can be avoided.

  Here, if the differential lock portion is not provided, it is necessary to ensure the required torque to the auxiliary drive wheel side only when the vehicle is escaped from the stacked state. For this reason, it is necessary to reduce the space | interval of the friction plates of the wet multi-plate clutch of a coupling part, or to increase the number of friction plates. In addition, there is also a problem that it is difficult to continue the four-wheel drive state by the coupling portion for a long time in order to protect the coupling portion from heat damage when exiting from the stack state.

  However, according to the above configuration, it is possible to easily secure the required torque on the side of the auxiliary drive wheel when the differential lock portion is switched to the connected state in the second four-wheel drive state, for example, when escaping from the stack state. This eliminates the need to secure the required torque by the coupling portion. In the coupling section, it is sufficient to ensure the torque required for the auxiliary drive wheels when the vehicle is turning or accelerating in the first four-wheel drive state. It can be kept small. Thereby, the number of friction plates of the wet multi-plate clutch of the coupling portion can be reduced, and the coupling portion can be downsized. Further, a large interval between the friction plates of the wet multi-plate clutch of the coupling portion can be ensured. In addition, the second four-wheel drive state in which the differential lock portion is connected can be continued for a long time, for example, when the diff lock portion is connected, and the coupling portion is released in the second four-wheel drive state. Therefore, the heat damage of the wet multi-plate clutch of the coupling portion can be avoided reliably and easily.

  In addition, since the distance between the friction plates of the wet multi-plate clutch of the coupling part can be secured and the number of friction plates can be reduced, the drag torque due to the viscous resistance of oil between the friction plates can be reduced, and the drag torque Loss can be reduced, and fuel consumption can be improved in a two-wheel drive state. Furthermore, when the two-wheel is towed, the amount of heat generated by the wet multi-plate clutch of the coupling portion can be reduced.

  Further, in the first four-wheel drive state, the engagement torque of the wet multi-plate clutch of the coupling portion is controlled by the actuator, so that the transmission torque to the auxiliary drive wheel side is appropriately set according to the traveling state of the vehicle. The four-wheel drive performance equivalent to that of a conventional standby-type four-wheel drive vehicle can be ensured.

  In the power transmission device for a four-wheel drive vehicle configured as described above, the actuator includes an electric motor, a screw shaft connected to an output shaft of the electric motor, and a nut member screwed to the screw shaft, One of the first four-wheel drive state, the second four-wheel drive state, and the two-wheel drive state is achieved when the nut member moves in the axial direction along the screw shaft by driving the electric motor. It is preferable to be switched to.

  According to the power transmission device for a four-wheel drive vehicle having the above-described configuration, the first four-wheel drive state, the second four-wheel drive state, and the two-wheel drive can be achieved simply by moving the nut member in the axial direction by driving the electric motor. It is possible to easily switch between states.

  In the power transmission device for a four-wheel drive vehicle configured as described above, the differential lock portion includes a drive-side counter shaft connected to the input shaft by a gear, a driven-side counter shaft connected to the output shaft by a gear, and the drive A sleeve that switches connection / disconnection of the side counter shaft and the driven counter shaft, and the nut member includes a pressing member that presses a friction plate of the wet multi-plate clutch, and a sleeve of the differential lock portion, It is preferable to be provided so as to move integrally in the axial direction.

  More specifically, the friction plate of the wet multi-plate clutch is pressed by the pressing member by the movement of the nut member toward the one end side in the axial direction, and the driving side counter shaft and the driven side by the sleeve The friction shaft of the wet multi-plate clutch by the pressing member is switched to the first four-wheel drive state by releasing the connection of the counter shaft, and the nut member is moved to the other end position in the axial direction. Is released, and the drive-side counter shaft and the driven-side counter shaft are connected by the sleeve, so that the second four-wheel drive state is switched, and the axial position of the nut member is changed. Movement of the friction plate of the wet multi-plate clutch by the pressing member is released, and the drive-side counter shaft and the sleeve by the sleeve are released. By connecting the driven-side counter shaft is released, it is preferable to switch to the two-wheel drive state.

  According to the power transmission device for a four-wheel drive vehicle configured as described above, the pressing member and the sleeve are moved in the axial direction integrally with the nut member simply by moving the nut member in the axial direction by driving the electric motor. Switching between the first four-wheel drive state, the second four-wheel drive state, and the two-wheel drive state can be easily performed.

  According to the power transmission device for a four-wheel drive vehicle of the present invention, the common actuator is used to switch the coupling portion between the engaged state and the released state, and to switch the differential lock portion between the connected state and the disconnected state. Therefore, the configuration can be simplified. In addition, it is possible to improve the torque transmission response to the auxiliary drive wheel side while reducing the drag torque of the wet multi-plate clutch of the coupling portion.

It is a figure showing typically an example of a four-wheel drive vehicle provided with a power transmission device concerning an embodiment of the present invention. It is a figure which shows typically the schematic structure of the power transmission device which concerns on embodiment, Comprising: It is a figure which shows 4WD-AUTO mode of a power transmission device. It is a figure which shows 2WD mode of a power transmission device. It is a figure which shows 4WD-LOCK mode of a power transmission device. It is a figure corresponding to Drawing 2 showing modification 1 of a power transmission device typically. It is a figure corresponding to Drawing 2 showing the power transmission device concerning other Embodiments 1 typically. It is a figure corresponding to Drawing 2 showing the power transmission device concerning other Embodiments 2 typically.

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

  First, a schematic configuration of a four-wheel drive vehicle including a power transmission device according to the embodiment will be described with reference to FIG. FIG. 1 illustrates a front wheel drive base (FF base) four-wheel drive vehicle. The four-wheel drive vehicle of this example is a hybrid vehicle equipped with an engine 10 and a motor generator as drive sources. The motor generator is disposed in a transaxle (hybrid unit) 11 and is connected to a battery (not shown) installed in the engine room at the front of the vehicle.

  As shown in FIG. 1, an engine 10 is arranged on the front side of the vehicle (upper side in FIG. 1). An output shaft of the engine 10 is connected to the transaxle 11. The transaxle 11 includes a front differential (differential mechanism) 12. The transaxle 11 outputs one or both of torque generated by the engine 10 and torque generated by the motor generator to the drive wheels.

  On the front side of the vehicle, a pair of left and right front wheels 14, 14 which are main drive wheels (drive wheels to which torque from a drive source is directly transmitted without going through the power transmission device 100) are arranged. The left and right front wheels 14 and 14 are connected to each other via a front differential 12. The left and right front wheels 14 and 14 and the front differential 12 are connected by axle shafts 13 and 13, respectively. Torque output from the transaxle 11 is transmitted to the front differential 12 so that the front wheels 14 and 14 are driven.

  Specifically, a ring gear 12 b is integrally provided on the differential case 12 a of the front differential 12. The ring gear 12b is meshed with the output gear 11a of the transaxle 11. The front differential 12 may have any configuration as long as it can perform a differential operation for differentially distributing torque to the left and right front wheels 14 and 14. In FIG. 1, the front differential 12 includes a pair of pinion gears 12c and 12c and a pair of side gears 12d and 12d that rotate while meshing with each other. The pinion gears 12c and 12c and the side gears 12d and 12d are accommodated in the differential case 12a.

  The front differential 12 is connected to the transfer 15. A propeller shaft (front wheel side rotating shaft) 16 extending toward the rear side (lower side in FIG. 1) of the vehicle is connected to the transfer 15. With the transfer 15, the torque output from the transaxle 11 can be taken out to the rear side of the vehicle.

  On the rear side of the vehicle, a pair of left and right rear wheels 19, 19 are arranged as auxiliary drive wheels (drive wheels to which torque from a drive source is transmitted via the power transmission device 100). The left and right rear wheels 19, 19 are connected to each other via a rear differential (differential mechanism) 17. The left and right rear wheels 19, 19 and the rear differential 17 are connected by axle shafts 18, 18, respectively. The configuration and function of the rear differential 17 are the same as those of the front differential 12 described above. That is, the rear differential 17 includes a differential case 17a, a ring gear 17b that meshes with a drive pinion gear 21a provided at a rear end portion of a drive pinion shaft (rear wheel side rotating shaft) 21, pinion gears 17c and 17c, and side gears 17d and 17d. It becomes the composition.

  A power transmission device 100 is provided between the propeller shaft 16 and the drive pinion shaft 21. The power transmission device 100 includes an actuator 130, and the actuator 130 is connected to an ECU (Electronic Control Unit) 200 as a control device. The ECU 200 controls the power transmission device 100 by controlling the actuator 130 based on detection signals from various sensors, settings of various switches, and the like. In this embodiment, the actuator 130 is driven when the driver operates a mode switching switch 201 disposed in the vicinity of the driver's seat. When the actuator 130 is driven, the operation state (operation mode) of the power transmission device 100 is changed to 2WD mode (two-wheel drive mode), 4WD-AUTO mode (first four-wheel drive mode), and 4WD-LOCK mode (first mode). 2 four-wheel drive mode). Note that the operation mode of the power transmission device 100 may be switched not only by the mode switching switch 201 but also by other operation means (for example, a lever or the like).

  Next, the power transmission device 100 provided in the four-wheel drive vehicle having the above configuration will be described in detail with reference to FIGS. The power transmission device 100 transmits the torque from the drive source to the front wheels 14 and 14 as the main drive wheels without transmitting the torque from the drive source to the rear wheels 19 and 19 as the auxiliary drive wheels, and the torque from the drive source. The four-wheel drive state transmitted to both the front wheels 14 and 14 and the rear wheels 19 and 19 can be switched.

  Specifically, as shown in FIG. 2, the power transmission device 100 includes a coupling unit 110 and a differential lock unit 120 as a torque transmission unit, and a drive unit shared by the coupling unit 110 and the differential lock unit 120. And an actuator 130. The coupling part 110, the differential lock part 120, and the actuator 130 are accommodated in the case 101. A propeller shaft 16 that is an input shaft is supported by a bearing 102 provided in the case 101. A differential carrier (not shown) that houses the rear differential 17 is integrally connected to the rear side of the case 101. The power transmission device 100 and the rear differential 17 are configured as one assembly. The power transmission device 100 and the rear differential 17 may be provided separately.

  In the power transmission device 100, the coupling unit 110 and the differential lock unit 120 are arranged in parallel. In the four-wheel drive state, torque can be transmitted from the propeller shaft 16 to the drive pinion shaft 21 that is the output shaft by any one of the coupling portion 110 and the differential lock portion 120. On the other hand, in the two-wheel drive state, torque transmission by the coupling unit 110 and the differential lock unit 120 is not performed. Hereinafter, each part of the power transmission device 100 will be described.

  First, the coupling part 110 is configured as a wet multi-plate clutch as shown in FIG. The coupling unit 110 has a configuration in which a plurality of clutch disks (friction plates) 111 and a plurality of clutch plates (friction plates) 112 are alternately arranged in the axial direction. The plurality of clutch discs 111 are spline-fitted to the inner peripheral surface of a clutch case 113 formed in a cylindrical shape, and are provided so as to be able to rotate integrally with the clutch case 113 and to be displaced in the axial direction. The plurality of clutch plates 111 are spline-fitted to the outer peripheral surface of the drive pinion shaft 21, and are provided so as to be able to rotate integrally with the drive pinion shaft 21 and be displaced in the axial direction.

  The clutch case 113 is provided so as to be able to rotate integrally with the propeller shaft 16. The clutch case 113 is provided so as to be rotatable relative to the drive pinion shaft 21 extending toward the rear differential 17. On the other hand, the clutch case 113 is not movable in the axial direction. An input gear 123a of the differential lock portion 120 is provided on the outer periphery of one end portion (front end portion) in the axial direction of the clutch case 113 so as to be integrally rotatable.

  On the other end side (rear end side) of the clutch case 113 in the axial direction, the friction plates 111 and 112 are pressed toward one side (front side) in the axial direction, and a pressing force is applied between the friction plates 111 and 112. A pressing member 114 is provided for generation. The pressing member 114 is provided integrally with the nut member 133 of the actuator 130 and is provided so as to be movable in the axial direction together with the nut member 133. In this case, the pressing member 114 is divided into a first pressing member 114 a and a second pressing member 114 b outside the clutch case 113. Specifically, the pressing member 114 is provided integrally with the nut member 133 of the actuator 130, and is one of the first pressing member 114a extending in a direction orthogonal to the axial direction and the friction plates 111 and 112 (here, , A friction plate 112) and a cylindrical second pressing member 114b extending in the axial direction. A thrust bearing 114c is interposed between the first pressing member 114a and the second pressing member 114b. The thrust bearing 114c is attached to one surface (the surface on the friction plates 111 and 112 side) of the first pressing member 114a, and the second pressing member 114b and the friction against the first pressing member 114a by the thrust bearing 114c. The plate 112 is rotatable. The second pressing member 114b is disposed concentrically with the clutch case 113, and the drive pinion shaft 21 is inserted into the second pressing member 114b. Further, a through hole (not shown) is formed in the first pressing member 114a, and the drive pinion shaft 21 is inserted through the through hole.

  In addition, the inside of the clutch case 113 is kept liquid-tight by a seal member (not shown), and oil (operating oil) is sealed in the clutch case 113. The clutch case 113 is not limited to a configuration in which oil is sealed, but oil that lubricates each part of the power transmission device 100 (oil in the case 101) or oil that lubricates the rear differential 17 is introduced into the clutch case 113. It is good also as composition to do.

  The coupling unit 110 is switched to the engaged state or the released state when the pressing member 114 is moved in the axial direction by the actuator 130. Specifically, when the power transmission device 100 is switched to the 2WD mode (see FIG. 3) or the 4WD-LOCK mode (see FIG. 4), the coupling unit 110 is switched to the released state. In the released state of the coupling portion 110, the first pressing member 114a is moved to the axial intermediate position shown in FIG. 3 or the axial rear end position shown in FIG. 4, and the first pressing member 114a is moved to the second pressing member. It is separated from 114b. Thereby, the pressing force on the friction plates 111 and 112 by the pressing member 114 does not act, oil flows between the friction plates 111 and 112, and the friction plates 111 and 112 are separated from each other. As a result, torque transmission from the propeller shaft 16 to the drive pinion shaft 21 by the coupling unit 110 is not performed. In this case, the movement of the friction plates 111 and 112 to the other side (rear side) in the axial direction is restricted by the step 113 a of the clutch case 113.

  On the other hand, when the power transmission device 100 is switched to the 4WD-AUTO mode (see FIG. 2), the coupling unit 110 is switched to the engaged state. In the engaged state of the coupling part 110, as shown in FIG. 2, the first pressing member 114a is moved to one side (front side) in the axial direction, and the second pressing member 114b is pressed by the first pressing member 114a. Is done. As a result, a pressing force is applied to the friction plates 111 and 112 by the pressing member 114, and the friction plates 111 and 112 are brought into pressure contact with each other. As a result, torque is transmitted from the propeller shaft 16 to the drive pinion shaft 21 by the coupling unit 110.

  Next, the differential lock portion 120 is provided in order to bring the propeller shaft 16 and the drive pinion shaft 21 into a directly connected state and to place the propeller shaft 16 and the drive pinion shaft 21 in a differential lock state (differential limited state). . As shown in FIG. 2, the differential lock portion 120 includes a counter shaft provided in parallel with the propeller shaft 16 and the drive pinion shaft 21. The countershaft is divided into a drive-side countershaft 121a and a driven-side countershaft 121b disposed coaxially on the rear side of the drive-side countershaft 121a. A synchronization mechanism 122 is provided between the drive-side countershaft 121a and the driven-side countershaft 121b to switch connection / disconnection between the drive-side countershaft 121a and the driven-side countershaft 121b. The drive-side countershaft 121a is supported by bearings 103 and 103 provided on the case 101. The driven countershaft 121b is supported by bearings 104 and 104 provided on the case 101.

  Specifically, the drive-side countershaft 121a is connected to the propeller shaft 16 through the input gears 123a and 123b that mesh with each other so as to transmit power. The input gear 123a is provided on the outer periphery of the clutch case 113 that is integrally attached to the propeller shaft 16, and the input gear 123b is provided on the front end side of the drive side countershaft 121a. As a result, the rotation of the propeller shaft 16 is transmitted to the drive-side countershaft 121a via the input gears 123a and 123b. A gear piece 122a of the synchronization mechanism 122 is provided on the rear end side of the drive side countershaft 121a.

  The driven countershaft 121b is connected to the drive pinion shaft 21 through output gears 124a and 124b that mesh with each other so as to transmit power. The output gear 124a is provided on the rear end side of the driven counter shaft 121b. The output gear 124 b is disposed behind the pressing member 114 of the coupling part 110. As a result, the rotation of the driven counter shaft 121b can be transmitted to the drive pinion shaft 21 via the output gears 124a and 124b. A gear piece 122b of the synchronization mechanism 122 is provided on the front end side of the driven counter shaft 121b.

  For example, a generally known synchromesh mechanism or the like is used as the synchronization mechanism 122, but a detailed description thereof will be omitted here and will be briefly described. The synchronization mechanism 122 includes gear pieces 122a and 122b, a substantially cylindrical sleeve 122c, and the like. Inner peripheral teeth 122d that can mesh with the gear piece 122a of the drive-side counter shaft 121a are formed at the front end portion of the inner peripheral surface of the sleeve 122c. Inner peripheral teeth 122e that can mesh with the gear piece 122b of the driven counter shaft 121b are formed at the rear end of the inner peripheral surface of the sleeve 122c.

  The sleeve 122c is provided integrally with the nut member 133 of the actuator 130, and is provided so as to be movable in the axial direction together with the nut member 133. A bearing 125 is interposed between the sleeve 122 c and the nut member 133, and the sleeve 122 c is rotatable with respect to the nut member 133 by the bearing 125. Then, when the sleeve 122c moves in the axial direction, the connection / disconnection between the drive-side counter shaft 121a and the driven-side counter shaft 121b is switched. The synchronization mechanism 122 may have other configurations as long as it can switch between connection / disconnection of the drive-side counter shaft 121a and the driven-side counter shaft 121b.

  The differential lock portion 120 is switched between a connected state and a non-connected state when the sleeve 122 c is moved in the axial direction by the actuator 130. Specifically, when the power transmission device 100 is switched to the 4WD-AUTO mode (see FIG. 2) or the 2WD mode (see FIG. 3), the differential lock unit 120 is switched to the unconnected state. In the non-connected state of the diff lock portion 120, the sleeve 122c is moved to one axial side (front side) from the axial intermediate position shown in FIG. 3, and the inner peripheral teeth 122e of the sleeve 122c and the driven side countershaft 121b. The meshing with the gear piece 122b is released. As a result, the connection between the drive-side counter shaft 121a and the driven-side counter shaft 121b by the sleeve 122c is released, and the drive-side counter shaft 121a and the driven-side counter shaft 121b are disconnected. As a result, torque transmission from the propeller shaft 16 to the drive pinion shaft 21 by the differential lock portion 120 is not performed.

  On the other hand, when the power transmission device 100 is switched to the 4WD-LOCK mode (see FIG. 4), the differential lock unit 120 is switched to the connected state. In the connected state of the differential lock portion 120, the sleeve 122c is moved to the rear end position in the axial direction shown in FIG. 4, and the inner peripheral teeth 122d and 122e of the sleeve 122c are engaged with the gear pieces 122a and 122b, respectively. As a result, the driving side countershaft 121a and the driven side countershaft 121b are connected. As a result, torque transmission from the propeller shaft 16 to the drive pinion shaft 21 is performed by the differential lock portion 120.

  Next, the actuator 130 switches the operation state of the coupling unit 110 and the diff lock unit 120 described above, and is commonly used for the coupling unit 110 and the diff lock unit 120 as shown in FIG. That is, the single actuator 130 switches the coupling state 110 between the engaged state and the released state, and the differential lock unit 120 between the connected state and the unconnected state in parallel. .

  As shown in FIG. 2, the actuator 130 includes an electric motor 131, a screw shaft 132, and a nut member (movable member) 133. One end of a screw shaft 132 is connected to the output shaft of the electric motor 131 so as to be integrally rotatable. The screw shaft 132 is a rod-like member extending in parallel with the drive pinion shaft 21, and a helical screw groove 132a is formed on the surface thereof. A bearing 134 that rotatably supports the screw shaft 132 is provided at the other end of the screw shaft 132. On the other hand, the axial movement of the screw shaft 132 is restricted.

  A nut member 133 is screwed onto the screw shaft 132. The nut member 133 is a ball screw, for example. In this case, the ball can be circulated between the nut member 133 and the screw shaft 132. As described above, the nut member 133 is movable in the axial direction integrally with the first pressing member 114 a of the pressing member 114 of the coupling portion 110 and the sleeve 122 c of the differential lock portion 120.

  When the screw shaft 132 is rotated by driving the electric motor 131, the nut member 133, the first pressing member 114 a, and the sleeve 122 c are moved along the screw shaft 132 in the axial direction. When the electric motor 131 is driven in the forward rotation direction, the nut member 133, the first pressing member 114a, and the sleeve 122c are moved to one side (front side) in the axial direction, and conversely, the electric motor 131 is moved in the reverse rotation direction. The nut member 133, the first pressing member 114a, and the sleeve 122c are moved to the other side (rear side) in the axial direction. The actuator 130 may have another configuration as long as the movable member that moves the first pressing member 114a and the sleeve 122c can be moved in the axial direction. For example, the actuator 130 may be moved in the axial direction by a linear motion motor. It is good also as a structure which moves.

  In this embodiment, the operating state of the coupling unit 110 and the differential lock unit 120 is switched according to the position of the nut member 133 of the actuator 130 in the axial direction, and accordingly, the power transmission device 100 operates in the 4WD-AUTO mode. (Refer to FIG. 2) The mode can be switched to any one of 2WD mode (see FIG. 3) and 4WD-LOCK mode (see FIG. 4). Hereinafter, each mode of the power transmission device 100 will be described.

  First, when the mode switch 201 is operated by the driver and the 4WD-AUTO mode is selected, the actuator 130 is driven, and as shown in FIG. 2, the nut member 133 is on one side (front side) in the axial direction. Moved to. As a result, the first pressing member 114a of the pressing member 114 of the coupling part 110 is moved to one side in the axial direction, the coupling part 110 is switched to the engaged state, and the sleeve 122c of the differential lock part 120 is moved in the axial direction. It moves to one side and the diff lock part 120 is switched to a non-connecting state. By switching the coupling portion 110 to the engaged state, torque is transmitted from the propeller shaft 16 to the drive pinion shaft 21, and torque is transmitted to the rear wheels 19 and 19.

  In the 4WD-AUTO mode, the transmission torque from the propeller shaft 16 to the drive pinion shaft 21 changes according to the position of the nut member 133 in the axial direction. That is, the axial position of the first pressing member 114a of the coupling part 110 changes according to the axial position of the nut member 133, and the pressing force of the pressing member 114 on the friction plates 111 and 112 changes. Along with this, the engagement torque of the coupling part 110 changes, and the transmission torque from the propeller shaft 16 to the drive pinion shaft 21 changes. Specifically, as the nut member 133 is moved to one side (front side) in the axial direction, the engagement torque of the coupling portion 110 increases and the transmission torque from the propeller shaft 16 to the drive pinion shaft 21 increases. Become. When the nut member 133 is moved to the front end position in the axial direction shown in FIG. 2, the engagement torque of the coupling portion 110 is maximized, and the transmission torque from the propeller shaft 16 to the drive pinion shaft 21 is maximized. Become.

  Next, when the driver operates the mode switching switch 201 to select the 2WD mode, the actuator 130 is driven and the nut member 133 is moved to the intermediate position (neutral position) in the axial direction shown in FIG. . Thereby, the first pressing member 114a of the pressing member 114 of the coupling part 110 is moved to the intermediate position in the axial direction shown in FIG. 3, the coupling part 110 is switched to the released state, and the sleeve 122c of the differential lock part 120 is moved. It moves to the intermediate position of the axial direction shown in FIG. 3, and the differential lock | rock part 120 is switched to a non-connecting state. When the coupling part 110 is switched to the released state and the differential lock part 120 is switched to the disconnected state, torque transmission from the propeller shaft 16 to the drive pinion shaft 21 is not performed, and torque is applied to the rear wheels 19 and 19 side. It will not be transmitted.

  Next, when the driver operates the mode switching switch 201 to select the 4WD-LOCK mode, the actuator 130 is driven, and the nut member 133 is moved to the other side (rear side) in the axial direction as shown in FIG. ). As a result, the first pressing member 114a of the pressing member 114 of the coupling part 110 is moved to the other side in the axial direction, the coupling part 110 is switched to the released state, and the sleeve 122c of the differential lock part 120 is moved to the other side in the axial direction. Moved to the side. Then, after the synchronizing device 122 synchronizes the rotation of the drive side countershaft 121a and the driven side countershaft 121b, when the sleeve 122c is moved to the rear end position shown in FIG. 4, the inner peripheral teeth 122d, 122e meshes with the gear pieces 122a and 122b, respectively. As a result, the drive-side counter shaft 121a and the driven-side counter shaft 121b are connected, and the differential lock portion 120 is switched to the connected state. By switching the differential lock portion 120 to the connected state, torque is transmitted from the propeller shaft 16 to the drive pinion shaft 21, and torque is transmitted to the rear wheels 19 and 19.

  In the 4WD-LOCK mode, the torque input from the propeller shaft 16 is directly output to the drive pinion shaft 21 via the differential lock unit 120. And the transmission torque by the differential lock | rock part 120 is larger than the largest transmission torque by the coupling part 110. FIG. In other words, the transmission torque by the power transmission device 100 in the 4WD-LOCK mode is larger than the maximum transmission torque by the power transmission device 100 in the 4WD-AUTO mode.

  According to this embodiment, the common actuator 130 switches between the engaged state and the released state of the coupling unit 110 and the switched state between the connected state and the unconnected state of the differential lock unit 120. The configuration of the device 100 can be simplified. Then, simply by moving the nut member 133 in the axial direction by driving the electric motor 131, the pressing member 114 and the sleeve 122c are moved in the axial direction integrally with the nut member 133, so that the 4WD-AUTO mode, 2WD mode, And 4WD-LOCK mode can be switched easily.

  Further, the torque transmission response to the rear wheels 19, 19 can be improved while reducing the drag torque of the coupling part 110. This point will be described in detail. In the 4WD-LOCK mode, the propeller shaft 16 and the drive pinion shaft 21 are directly connected by switching the differential lock portion 120 to the connected state, so that the torque required for the rear wheels 19 and 19 can be easily secured. It is possible to improve the four-wheel drive performance when climbing or escaping from the stack. And the torque transmission responsiveness to the rear wheels 19 and 19 side can be improved, and the phenomenon of sliding down when starting uphill can be avoided.

  Here, if the differential lock part 120 is not provided, it is necessary to ensure only the coupling part 110 the required torque to the rear wheels 19 and 19 when escaping from the stacked state. For this reason, it is necessary to reduce the interval between the friction plates 111 and 112 of the coupling portion 110 or to increase the number of the friction plates 111 and 112. In addition, there is also a problem that it is difficult to continue the four-wheel drive state by the coupling unit 110 for a long time from the viewpoint of protecting the coupling unit 110 from heat damage when exiting the stack state.

  However, according to this embodiment, when the differential lock unit 120 is switched to the connected state in the 4WD-LOCK mode, the required torque to the rear wheels 19 and 19 when the vehicle exits from the stacked state can be easily achieved by the differential lock unit 120. It is not necessary to secure the required torque by the coupling part 110. In the coupling part 110, it is sufficient to secure at least the torque required for the rear wheels 19 and 19 when the vehicle is turning or accelerating in the 4WD-AUTO mode. Combined capacity) can be kept small. Thereby, the number of the friction plates 111 and 112 of the coupling part 110 can be reduced, and the coupling part 110 can be reduced in size. Further, a large interval between the friction plates 111 and 112 of the coupling part 110 can be ensured. Further, when exiting from the stack state, the 4WD-LOCK mode in which the differential lock unit 120 is connected can be continued for a long time, and in this 4WD-LOCK mode, the coupling unit 110 is switched to the released state. Therefore, the heat damage of the coupling part 110 can be avoided reliably and easily.

  And since the space | interval of the friction plates 111 and 112 of the coupling part 110 can be ensured or the number of the friction plates 111 and 112 can be decreased, the drag torque by the viscous resistance of the oil between the friction plates 111 and 112 can be reduced. Thus, loss due to drag torque can be reduced, and fuel efficiency can be improved in the 2WD mode. Further, it is possible to suppress a reduction in regenerative energy on the front wheels 14 and 14 side during regenerative braking. Furthermore, the amount of heat generated by the coupling unit 110 can be reduced when the two-wheel is towed.

  In the 4WD-AUTO mode, by controlling the engagement torque of the coupling unit 110 by the actuator 130, the transmission torque to the rear wheels 19 and 19 can be appropriately controlled according to the traveling state of the vehicle. The same four-wheel drive performance as that of a conventional standby four-wheel drive vehicle can be ensured.

-Other embodiments-
The present invention is not limited only to the above-described embodiments, and all modifications and applications within the scope of the claims and within the scope equivalent to the scope are possible.

  The coupling unit is not particularly limited as long as it includes a wet multi-plate clutch, and may have a configuration other than those described above. In addition, the differential lock unit is not particularly limited as long as it can directly connect the input shaft and the output shaft, and may have a configuration other than those described above.

  In the above embodiment, the pressing member 114 of the coupling unit 110 includes the first pressing member 114a and the second pressing member 114b. However, the actuator 130 can press the friction plates 111 and 112. Any other configuration may be used. For example, as shown in FIG. 5, the pressing member 115 may have a configuration in which a first pressing portion 115a and a second pressing portion 115b are integrally formed. In the first modification shown in FIG. 5, the first pressing portion 115 a extends in a direction orthogonal to the axial direction and is integrally attached to the nut member 133 of the actuator 130. The second pressing portion 115 b is formed in a cylindrical shape and extends in the axial direction, and is disposed concentrically with the clutch case 113. The second pressing portion 115b is integrally attached to one surface (the surface on the friction plates 111 and 112 side) of the first pressing portion 115a. A thrust bearing 115c is interposed between the second pressing portion 115b and one of the friction plates 111 and 112 (here, the friction plate 112). The thrust bearing 115c is attached to the friction plate 112, and the friction plate 112 is rotatable with respect to the pressing member 115 (second pressing portion 115b) by the thrust bearing 115c.

  Moreover, in the said embodiment, although the power transmission device 100 was arrange | positioned between the propeller shaft 16 and the drive pinion shaft 21, if it is a location which can transmit the torque from a drive source to the sub drive wheel side, it will be other than that You may arrange | position a power transmission device in a location. For example, a power transmission device may be arranged between the front propeller shaft and the rear propeller shaft.

  In the above embodiment, the power transmission device 100 has both the 4WD-AUTO mode and the 4WD-LOCK mode. However, as shown in FIGS. 6 and 7, the power transmission device has a 4WD-AUTO mode and a 4WD-LOCK mode. A configuration in which only one of the modes is provided is also possible.

  A power transmission device 100A according to another embodiment 1 shown in FIG. 6 has a configuration in which the diff lock portion 120 is omitted from the power transmission device 100 of the above-described embodiment shown in FIG. The power transmission device 100A can be switched to either the 2WD mode or the 4WD-AUTO mode, and does not include the 4WD-LOCK mode of the power transmission device 100 of the above embodiment. For convenience, the input gear 123a provided on the outer periphery of one end (front end) in the axial direction of the clutch case 113 and the output gear 124b provided on the drive pinion shaft 21 are left.

  In contrast, a power transmission device 100B according to another embodiment 2 shown in FIG. 7 has a configuration in which the coupling portion 110 is omitted from the power transmission device 100 according to the above-described embodiment shown in FIG. The power transmission device 100B can be switched to either the 2WD mode or the 4WD-LOCK mode, and does not include the 4WD-AUTO mode of the power transmission device 100 of the above embodiment. For convenience, a bearing 105 that supports the propeller shaft 16 and a bearing 106 that supports the drive pinion shaft 21 are added.

  Here, by providing the coupling part 110 and the differential lock part 120 so as to be detachable with respect to the case 101, three power transmission devices 100, 100A, and 100B can be provided as needed by the same unit. . That is, any one of the power transmission device 100 having both the 4WD-AUTO mode and the 4WD-LOCK mode, the power transmission device 100A having only the 4WD-AUTO mode, and the power transmission device 100B having only the 4WD-LOCK mode. Can be selectively provided.

  In the above embodiment, an example in which the present invention is applied to a front wheel drive-based four-wheel drive vehicle has been described, but the present invention is also applicable to a rear wheel drive-based four-wheel drive vehicle. Moreover, although the example which applied this invention to the hybrid vehicle provided with the engine and the motor generator as a drive source was given, this invention is applicable also to the vehicle provided only with the engine as a drive source.

  The present invention includes a two-wheel drive state in which torque from a drive source is transmitted to only the main drive wheel without transmitting it to the sub drive wheel, and four-wheel drive in which torque from the drive source is transmitted to both the main drive wheel and the sub drive wheel. The present invention can be used for a power transmission device of a four-wheel drive vehicle configured to be switchable between states.

10 Engine 14 Front wheel (Main drive wheel)
16 Propeller shaft (input shaft)
19 Rear wheel (sub-drive wheel)
21 Drive pinion shaft (output shaft)
DESCRIPTION OF SYMBOLS 100 Power transmission device 110 Coupling part 111 Clutch disc (friction plate)
112 Clutch plate (friction plate)
114 Pressing member 120 Differential lock part 121a Driving side countershaft 121b Driven side countershaft 122 Synchronizing mechanism 122c Sleeve 130 Actuator 131 Electric motor 132 Screw shaft 133 Nut member

Claims (5)

A two-wheel drive state in which the torque from the drive source is transmitted to only the main drive wheel without being transmitted to the sub drive wheel, and a four-wheel drive state in which the torque from the drive source is transmitted to both the main drive wheel and the sub drive wheel. A power transmission device for a four-wheel drive vehicle configured to be switchable,
Arranged between an input shaft provided on the main drive wheel side and an output shaft provided on the sub drive wheel side;
A coupling portion configured to be able to switch between an engagement state in which torque input from the input shaft is transmitted to the output shaft in accordance with an engagement torque of a wet multi-plate clutch and a release state in which torque transmission is not performed; ,
A differential lock portion configured to be able to switch between a connected state in which the input shaft and the output shaft are directly connected and a non-connected state in which torque transmission is not performed;
Power transmission of a four-wheel drive vehicle, wherein switching between the engaged state and the released state of the coupling portion and switching between the connected state and the disconnected state of the differential lock portion are performed by a common actuator. apparatus. The power transmission device for a four-wheel drive vehicle according to claim 1,
A first four-wheel drive state in which the coupling portion is in an engaged state, and the differential lock portion is in a disconnected state;
A second four-wheel drive state in which the coupling portion is in a released state, and the differential lock portion is in a connected state;
A power transmission device for a four-wheel drive vehicle, wherein the actuator is switched between a two-wheel drive state in which the coupling portion is in a released state and the differential lock portion is in a disconnected state. The power transmission device for a four-wheel drive vehicle according to claim 2,
The actuator includes an electric motor, a screw shaft connected to the output shaft of the electric motor, and a nut member screwed to the screw shaft,
One of the first four-wheel drive state, the second four-wheel drive state, and the two-wheel drive state is caused by the nut member moving in the axial direction along the screw shaft by driving the electric motor. A power transmission device for a four-wheel drive vehicle characterized by being switched to one. The power transmission device for a four-wheel drive vehicle according to claim 3,
The differential lock unit includes a drive-side counter shaft connected to the input shaft by a gear, a driven-side counter shaft connected to the output shaft by a gear, and connection / non-connection of the drive-side counter shaft and the driven-side counter shaft. A sleeve for switching the connection,
The four-wheeled vehicle characterized in that a pressing member that presses the friction plate of the wet multi-plate clutch and a sleeve of the differential lock portion are provided on the nut member so as to move integrally in the axial direction. Power transmission device for driving car. The power transmission device for a four-wheel drive vehicle according to claim 4,
As the nut member moves toward one end in the axial direction, the friction plate of the wet multi-plate clutch is pressed by the pressing member, and the connection of the driving side counter shaft and the driven side counter shaft by the sleeve is released. Is switched to the first four-wheel drive state,
The movement of the nut member to the other end position in the axial direction releases the pressing of the friction plate of the wet multi-plate clutch by the pressing member, and the drive-side counter shaft and the driven-side counter shaft are moved by the sleeve. By being connected, it is switched to the second four-wheel drive state,
When the nut member moves to an intermediate position in the axial direction, the pressing of the friction plate of the wet multi-plate clutch by the pressing member is released, and the driving side counter shaft and the driven side counter shaft are connected by the sleeve. The power transmission device for a four-wheel drive vehicle can be switched to the two-wheel drive state by releasing.

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