JP2010260383A - Drive force transmission device for four-wheel-drive vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an on-demand type full time four-wheel-drive vehicle of an FF vehicle base with favorable fuel economy by reducing a friction loss by a rear wheel drive system during two-wheel drive. <P>SOLUTION: This drive force transmission device includes a connecting/disconnecting device 28 for connecting and disconnecting a drive force from a front wheel differential device 18 to a first drive force transmission direction converting part 20, and a multi-plate clutch mechanism 30 provided between an output of a rear wheel differential device 26 and a right rear wheel to continuously adjust a fastening force. Drag torque when releasing fastening of the multi-plate clutch mechanism 30 is made smaller than the friction torque of the rear wheel drive system between the first drive force transmission direction converting part 20 and a second drive force transmission direction converting part 24. A controller 25 disconnects the connecting/disconnecting device 28 and releases the fastening of the multi-plate clutch mechanism 30 when a mode is switched to a two-wheel drive mode, and thereby the controller stops the rotation of the rear wheel drive system. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a drive power transmission device for a four-wheel drive vehicle capable of switching between two-wheel drive and four-wheel drive, and more particularly, for a four-wheel drive vehicle that stops rotation of a portion that is not involved in transmission of drive force during two-wheel drive. The present invention relates to a driving force transmission device.

  In a conventional so-called on-demand full-time four-wheel drive vehicle, the front wheel is driven during two-wheel drive, and the drive force distribution device performs drive force distribution control to the rear wheel during four-wheel drive. As a force transmission device, for example, the one shown in FIG. 18 is known.

  In FIG. 18, the driving force transmission device 200 is provided in a four-wheel drive vehicle 202, and the driving force from the engine 204 is shifted by a transmission 206 to change the driving force direction with the front wheel differential device 208 in the driving force transmission device 200. The output from the driving force direction changing unit 210 is transmitted to the driving force distribution device 214 known as an electronically controlled coupling device via the propeller shaft 212.

  When the driving force distribution device 214 is opened (disconnected state) during two-wheel drive, the driving force is transmitted to the front wheel differential device 208 without being distributed to the rear wheel differential device 224, and the front wheel differential device is transmitted. 208 absorbs the rotational speed difference between the left front wheel 216 and the right front wheel 218 and applies the same torque to the left front wheel 216 and the right front wheel 218 for rotation.

  In the case where the driving force distribution device 214 in the four-wheel drive is fastened (connected state), the driving force is rear wheel differential via the drive pinion 220 and the ring gear 222 connected to the driving force distribution device 214. Also transmitted to the device 224, the rear wheel differential 224 absorbs the rotational speed difference between the left rear wheel 226 and the right rear wheel 228 and rotates the left rear wheel 226 and the right rear wheel 228 with equal torque.

  In general, on-demand full-time four-wheel drive vehicles are available in two-wheel drive mode, four-wheel drive auto mode, and four-wheel drive lock mode as drive modes that can be selected by the driver during operation. Yes.

  The two-wheel drive mode is a mode in which the drive force distribution device 214 of the drive force transmission device 200 is opened and used in a two-wheel drive state. Select when driving.

  In the four-wheel drive auto mode, various vehicle states during traveling are detected by sensors, and the distribution of driving force to the front and rear wheels of the driving force distribution device 214 is optimized by an ECU (Electronic Control Unit) based on the detection signal. This is a mode that automatically controls, and is a four-wheel drive that can always be selected regardless of the road surface condition.

  In this mode, the fastening force of the driving force distribution device 214 is continuously increased or decreased by the actuator, and the driving force distribution of the front and rear wheels is distributed between the two-wheel drive state in which the driving force to the rear wheels is substantially zero and the maximum fastening force. Control.

The four-wheel drive lock mode is a mode in which the driving force distribution device 214 is maintained at the maximum fastening force regardless of the vehicle state detected by various sensors, and the driving performance as a four-wheel drive is maximized when driving on rough roads. Select if you want to.

Japanese Patent Laid-Open No. 11-125279

  However, in such a conventional driving force transmission device for a four-wheel drive vehicle, even in the two-wheel drive mode in which the driving force distribution device 214 is opened, the driving force from the transmission 206 is converted into a driving force direction conversion unit. 210, the driving side (front wheel side) of the propeller shaft 212 and the driving force distribution device 214 is rotated.

  In other words, the driving force direction changing unit 210, the propeller shaft 212, the multi-plate clutch mechanism 214, the drive pinion 220, and the rear wheel differential are also in two-wheel driving where the driving force is not transmitted to the rear wheel with the driving force distribution device 214 opened. Each component of the rear wheel driving force system including the device 224 rotates, and there is a problem in that fuel consumption is reduced due to oil agitation resistance, friction loss of the bearing portion, and the like in the rear wheel driving force system.

  At the same time, even in the two-wheel drive mode in which the driving force distribution device 214 is opened, the left rear wheel 226 and the right rear wheel 228 and the rear wheel differential device 224 are directly connected to each other. As the rear wheel 228 rotates, the rear wheel drive transmission system on the driven side (rear wheel side) of the rear wheel differential 224, the drive pinion 220, and the driving force distribution device 214 rotates.

  In addition, the driving force distribution device 214 performs connection / disconnection of driving force and control of transmission torque by a multi-plate clutch mechanism, and a plurality of clutch plates are lubricated and cooled with oil. The so-called drag torque generated by the viscous resistance of oil generated by the difference in rotational speed between the driving side and the driven side of the clutch plate and the friction loss due to contact between the clutch plates is the friction torque of the drive pinion 220 and the rear wheel differential 224. Therefore, the drive pinion 220 and the rear wheel differential device 224 are rotated from the driving force distribution device 214 side, which causes a problem of worsening fuel consumption.

  In order to reduce the drag torque, when the oil supply to the multi-plate clutch mechanism of the driving force distribution device 214 is stopped or the oil amount is extremely reduced, the drag torque is generated due to the viscous resistance of the oil. The drag torque can be reduced or eliminated. However, at the time of driving force distribution control, the multi-plate clutch mechanism may be seized if sufficient lubrication is not performed.

  Further, there is a method of increasing the clearance between the clutches in order to reduce the drag torque, but there is a problem that the responsiveness at the time of clutch engagement is deteriorated.

The present invention provides a driving force transmission device for a four-wheel drive vehicle that reduces oil viscosity resistance and friction loss to reduce fuel consumption by reliably stopping the rotation of the rear wheel drive system in the two-wheel drive mode. Objective.

The present invention can switch between a four-wheel drive mode that automatically controls the distribution of the driving force transmitted to the front wheels and the rear transportation according to the running conditions, and a two-wheel drive mode that transmits the driving force only to the front transportation. In a driving force transmission device for a four-wheel drive vehicle,
A front wheel differential device that receives driving force from the engine and distributes the driving force to the left and right front wheels;
A first driving force transmission direction conversion section that changes the rotational direction of the driving force from the engine and transmits the driving force to the rear transportation;
Receiving a driving force from the first driving force transmission direction conversion unit, changing the rotation direction, and transmitting the second driving force transmission direction conversion unit to the rear trans-differential device;
A differential device for rear transportation that distributes the driving force to the left and right rear wheels;
A multi-plate clutch mechanism that is provided between one of the outputs of the rear differential and one of the left and right rear wheels and capable of continuously adjusting the fastening force;
Drag torque for setting the drag torque when releasing the engagement of the multi-plate clutch mechanism to be smaller than the friction torque between the first drive force transmission direction conversion portion and the second drive force transmission direction conversion portion A reduction mechanism;
In the two-wheel drive mode, the connecting / disconnecting device is disconnected and the multi-plate clutch mechanism is released to stop the rotation of the second driving force transmission direction changing portion from the first driving force transmission direction changing portion. A controller for coupling the connecting / disconnecting device in the drive mode and adjusting the fastening force of the multi-plate clutch mechanism according to the running condition of the vehicle;
It is provided with.

  Here, the drag torque reduction mechanism has a structure in which the rear wheel differential device and the multi-plate clutch mechanism are separated into separate chambers so that the lubricating oil of the rear wheel differential device and the lubricating oil of the multi-plate clutch mechanism are not mixed.

  In the two-wheel drive mode in which the multi-plate clutch mechanism is disengaged, the drag torque reduction mechanism makes the gap between the clutch plates wider than a predetermined value and stops or restricts the supply of lubricating oil to the clutch plate. Is provided with a lubricating oil supply mechanism for supplying lubricating oil to the clutch plate in the four-wheel drive mode.

The lubricating oil supply mechanism is provided with an oil pump that is driven reversely in the two-wheel drive mode and driven by the output shaft of the rear trans-differential device that rotates forward in the four-wheel drive mode.

  The oil pump is a gear pump, and an anti-seizure treatment layer is formed on the sliding contact surface with the housing of the gear pump.

  The oil pump is driven through a one-way clutch provided between the output shaft of the rear wheel differential device, and stops supplying the lubricating oil to the multi-plate clutch mechanism by idling the one-way clutch in the two-wheel drive mode. In the four-wheel drive mode, the oil pump is rotated forward to supply lubricating oil to the multi-plate clutch mechanism.

The lubricant supply mechanism
An oil pump driven by an output shaft of a rear trans-differential device that rotates reversely in the two-wheel drive mode and rotates forward in the four-wheel drive mode;
A first suction path check valve that causes the oil pump to suck oil from the first suction path when the two-wheel drive mode is reversed;
A first discharge path check valve that discharges oil discharged from the oil pump to a portion other than the multi-plate clutch mechanism when the two-wheel drive mode is reversed;
A second suction path check valve that causes the oil pump to suck oil from the second suction path during forward rotation in the four-wheel drive mode;
A second discharge path check valve that causes the multi-plate clutch mechanism to discharge oil discharged from the oil pump during forward rotation in the four-wheel drive mode;
Is provided.

The lubricant supply mechanism
An oil pump driven by an output shaft of a rear trans-differential device that rotates reversely in the two-wheel drive mode and rotates forward in the four-wheel drive mode;
A suction path check valve that causes oil to be sucked into the oil pump from the first suction path and discharged into the tank through the discharge / suction path when the two-wheel drive mode is reversed;
A discharge path check valve that causes the multi-plate clutch mechanism to discharge oil sucked into the oil pump from the discharge combined suction path during forward rotation in the four-wheel drive mode;
Is provided.

The lubricant supply mechanism
An oil pump driven on the output side of the multi-plate clutch mechanism;
An opening and closing mechanism that stops the supply of lubricant by closing the lubrication path in the two-wheel drive mode, and supplies the lubricant by opening the lubrication path in the four-transmission drive mode;
Is provided.

The opening and closing mechanism
A valve chamber that is formed in the direction of the inner shaft of the output shaft of the rear wheel differential device in which the multi-plate clutch mechanism is disposed, and that is supplied with lubricating oil from an oil pump;
A valve member that is slidably housed in the valve chamber and moves in conjunction with an axially movable piston that connects and disconnects the clutch plate of the multi-plate clutch mechanism;
An oil supply hole for supplying lubricating oil between the clutch plates of the multi-plate clutch mechanism;
The movement of the valve member in conjunction with the movement of the piston to the clutch non-engagement position in the two-wheel drive mode closes the oil supply hole to shut off the lubricating oil, and the piston moves to the clutch engagement position in the four-wheel drive mode. Lubricating oil is supplied by opening the oil supply hole by the movement of the interlocked valve member.

The opening and closing mechanism
An oil chamber that is formed in the direction of the inner shaft of the output shaft of the rear wheel differential device in which the multi-plate clutch mechanism is disposed, and is supplied with lubricating oil from an oil pump;
An outer peripheral spline having a wider valley than the peak formed on the outer periphery of the output shaft;
An inner hub of a multi-plate clutch mechanism that forms an inner peripheral spline with a wider valley than a peak that fits to the outer peripheral spline of the output shaft;
In the two-wheel drive mode, the lubricating oil for the multi-plate clutch mechanism is shut off at the contact position of the outer peripheral spline with the inner peripheral spline due to the reverse rotation of the output shaft. A pair of oil supply holes formed in a valley portion of an outer peripheral spline and an inner peripheral spline for supplying lubricating oil to the multi-plate clutch mechanism at a contact position with respect to the peripheral spline;
Is provided.

  The drag torque reduction mechanism includes a spring member that urges the clutch plates in a direction that increases the interval between the clutch plates.

  The drag torque reduction mechanism includes a spring member that urges the clutch plate in a direction of widening the gap between the piston and the piston that presses the clutch plate.

The controller
The switching from the 2-transport mode to the 4-transport mode is performed after the multi-plate clutch mechanism is fastened, and then the connecting / disconnecting device is fastened. The switching from the 4-wheel drive mode to the 2-transport mode is the multi-plate clutch mechanism. After disconnecting, the connection / disconnection device is disconnected.

  According to the present invention, a connecting / disconnecting device is provided on the output shaft from the front wheel differential to the rear wheel drive system, and a multi-function that functions as a driving force distribution device on one of the rear wheel drive shafts of the rear wheel differential. Distributing the driving force between the front and rear wheels in the four-wheel drive mode by providing a plate clutch mechanism and reducing the drag torque caused by friction when the multi-plate clutch device is released in the two-wheel drive mode. Function Rotation of the rear wheel drive system from the first driving force transmission direction changing portion on the output side of the connecting / disconnecting device in the two-wheel drive mode to the second driving force transmission direction changing portion on the input side of the rear wheel differential device A function to completely stop, and a function to synchronize to connect the connecting / disconnecting device by increasing the rotation of the rear wheel drive system that is stopped when switching from the two-wheel drive mode to the four-wheel drive mode during traveling. Can be realized properly.

  In addition, in order to stop the rotation of the rear wheel drive system in the two-wheel drive mode, a multi-plate clutch mechanism can be provided between the input side second driving force transmission direction converting portion of the rear wheel differential device. However, since the conventional rear wheel differential cannot be used as it is, the structure is complicated, the clutch torque capacity is increased, the size and weight are increased, and the cost is increased. By providing a multi-plate clutch mechanism on the rear wheel drive shaft between the device and the rear wheel, the clutch capacity is halved and the conventional rear wheel differential can be used as it is, and the multi-plate clutch mechanism is downsized. , It can be reduced in weight and cost.

  In addition, because the rear wheel drive system is completely stopped in the two-wheel drive mode, friction loss does not occur and fuel consumption deterioration can be prevented, and it can be used in the two-wheel drive mode while being a four-wheel drive vehicle. The fuel consumption when the vehicle is in a vehicle can be made as good as that of a two-wheel drive vehicle.

In addition, the supply of lubricating oil to the multi-plate clutch mechanism is stopped in the two-wheel drive mode, so that the drag torque generated by the agitation of the lubricating oil by the clutch plate in the disengaged state is greatly reduced, and the rear wheel drive system The rotation can be stopped reliably.

The explanatory view which showed the embodiment of the driving force transmission device for four-wheel drive vehicles by the present invention with the skeleton figure FIG. 1 is an explanatory view showing an embodiment of the multi-plate clutch mechanism of FIG. 1 in a skeleton diagram. Explanatory drawing which showed the comparative example of the multi-plate clutch mechanism which implement | achieves the same function as FIG. 2 with the skeleton figure Sectional drawing which showed embodiment of the multi-plate clutch mechanism used by this invention Explanatory drawing which showed the attachment state of the spring member for space ensuring in the multi-plate clutch mechanism of FIG. FIG. 5 is an exploded view showing a structure for attaching a spring member to the clutch plate of FIG. Explanatory drawing which showed the lubrication mechanism provided in the multi-plate clutch mechanism of this invention with the skeleton figure Explanatory drawing which showed switching of the suction port and discharge port in the two-wheel drive mode and four-wheel drive mode of the oil pump of FIG. Explanatory drawing showing another lubrication mechanism using a one-way clutch in the oil pump as a skeleton diagram Hydraulic circuit diagram showing lubrication mechanism of multi-plate clutch mechanism that switches oil pump path by check valve Hydraulic circuit diagram showing another lubrication mechanism of multi-plate clutch mechanism that switches oil pump path by check valve Sectional drawing which showed embodiment of the multi-plate clutch mechanism which provided the lubrication mechanism which opens and closes a lubrication path | route in response to the piston which adjusts clutch fastening force Sectional drawing which took out and showed the part of the clutch disengagement state of the centerline upper side in the multi-plate clutch mechanism of FIG. Sectional drawing which took out and showed the part of the clutch fastening state of the lower centerline in the multi-plate clutch mechanism of FIG. Sectional view showing an embodiment of a multi-plate clutch mechanism provided with a lubrication mechanism that opens and closes a lubrication path by utilizing the difference in the rotation direction of the input / output drive shaft Explanatory drawing which showed the lubrication mechanism which opens and closes a lubrication path | route using the difference in the rotation direction of the input-output drive shaft of FIG. 15 using spline fitting. The graph which showed change of drag torque with respect to the number of rotations of the multi-plate clutch mechanism when the supply of lubricating oil is stopped in comparison with the conventional example Explanatory drawing showing a conventional driving force transmission device for a four-wheel drive vehicle

  FIG. 1 is an explanatory diagram showing, in a skeleton diagram, an embodiment of a driving force transmission device for a four-wheel drive vehicle according to the present invention. In FIG. 1, the driving force transmission device 10 of the present embodiment is mounted on an on-demand full-time four-wheel drive vehicle 12, and includes a front wheel differential device 18, a first driving force transmission direction conversion unit 20, and a propeller shaft 22. The second driving force transmission direction conversion unit 24 and the rear wheel differential device 26 are provided, and a connecting / disconnecting device 28 is further provided between the front wheel differential device 18 and the first driving force transmission direction conversion unit 20, and the rear wheel difference. A multi-plate clutch mechanism 30 that functions as a driving force distribution device is provided between the driving device 26 and the rear wheel drive shafts 76a and 76b between the right rear wheel 82, for example.

  The driving force from the engine 14 is shifted by the transmission 16 and is input to the input drive shaft 45 of the connection / disconnection device 28 via the drive gear 32 of the transmission 16 and the ring gear 34 of the front wheel differential 18.

  The connecting / disconnecting device 28 is uncoupled in the two-wheel drive mode and coupled in the four-wheel drive mode by a control signal E1 from an ECU (Electronic control unit) 25 that functions as a controller. As the connecting / disconnecting device 28, for example, a meshing clutch mechanism is used.

  The driving force from the drive gear 32 of the transmission 16 drives the left front wheel drive shaft 44 and the right front wheel drive shaft 46 via the ring gear 34, pinions 36, 38 and side gears 40, 42 of the front wheel differential 18. The left front wheel 48 and the right front wheel 50 are rotated to transmit the driving force to the road surface. Even if there is a difference in rotational speed between the left front wheel 48 and the right front wheel 50 due to cornering or changes in road surface conditions, the front wheel differential 18 absorbs this rotational speed difference, and torque equal to the left front wheel 48 and the right front wheel 50. Can be rotated.

When the driver switches, for example, to the four-wheel auto mode by operating a switch during operation, the ECU 25 first engages the multi-plate clutch mechanism 30 and then connects the connecting / disconnecting mechanism 28 by the control signal E2, thereby connecting / disconnecting the connecting / disconnecting device 28. Driving force can be transmitted to the left rear wheel 80 and the right rear wheel 82.
Thus, by first engaging the multi-plate clutch mechanism 30, it is possible to increase the rotation of the rear wheel drive system that is stopped in the two-wheel drive mode and to synchronize the connecting / disconnecting device 28. .

  The driving force output by the coupling of the connecting / disconnecting device 28 is transmitted to the bevel gear 52 of the first driving force transmission direction conversion unit 20 and rotates the output drive shaft 55 from the bevel gear 52 via the output pinion 54. Furthermore, it is transmitted via the universal joint 56, the propeller shaft 22, and the universal joint 58 from the drive pinion 60 of the second driving force transmission direction converting portion 24 to the ring gear 62 of the rear wheel differential device 26, and the transmission direction is converted to the ring. The left rear wheel drive shaft 74 and the right rear wheel drive shaft 76a are driven through the gear 62, the pinions 66 and 68, and the side gears 70 and 72. At this time, since the multi-plate clutch mechanism 30 is in the engaged state, The driving force of the rear wheel drive shaft 76a is transmitted to the right rear wheel drive shaft 76b on the output side of the multi-plate clutch mechanism 30, thereby rotating the left rear wheel 80 and the right rear wheel 82 to transmit the driving force.

  The rear wheel differential device 26 absorbs this rotational speed difference even when a difference in rotational speed occurs between the left rear wheel 80 and the right rear wheel 82 due to cornering or a change in road surface condition. An equal torque can be transmitted to the wheel 82 for rotation.

  The fastening force of the multi-plate clutch mechanism 30 can be continuously adjusted by a servo motor, which will be clarified later, by a control signal E2 of the ECU 25. To control the driving force distribution.

  When switching from the four-wheel drive mode to the two-wheel drive mode, the ECU 25 releases the engagement force of the multi-plate clutch mechanism 30 and eliminates transmission of the drive force via the connecting / disconnecting device 28 to the rear wheel side. Then, the connecting / disconnecting device 28 is disconnected.

  In the two-wheel drive mode, by releasing the engagement of the multi-plate clutch mechanism 30 and simultaneously disconnecting the multi-plate clutch mechanism 30 by the connecting / disconnecting device 28, in the present embodiment, the first driving force transmission direction changing unit 20 can The rotation of the rear wheel drive system up to the drive force transmission direction conversion unit 24 is stopped to prevent a reduction in fuel consumption due to friction loss that occurs in the two-wheel drive mode.

  In order to stop the rear wheel drive system between the first drive force transmission direction conversion unit 20 and the second drive force transmission direction conversion unit 24 in the two-wheel drive mode, multiple plates are used against the friction of the rear wheel drive system. It is necessary to configure the multi-plate clutch mechanism 30 so as to reduce the drag torque when the engagement of the clutch mechanism 30 is released.

  The stop of the rear wheel drive system in the two-wheel drive mode will be described in detail as follows. When the connection between the side gear 72 of the rear wheel differential 26 and the right rear wheel drive shaft 76b is disconnected due to the disengagement of the multi-plate clutch mechanism 30, the rotation of the right rear wheel 82 is not transmitted to the side gear 72, and therefore the left rear wheel 80 The rotation of the side gear 70 caused by the rotation causes the side gear 72 to rotate in the opposite direction via the pinions 66 and 68.

  At this time, since the rotational resistance from the drive pinion 60 to the bevel gear 52 connected to the ring gear 62 is larger than the rotational resistance of the pinions 66 and 68 and the side gear 70, the ring gear 62 does not rotate. The fact that the ring gear 62 does not rotate means that the rear wheel drive system from the bevel gear 52 on the output side of the connecting / disconnecting device 28 to the drive pinion 60 of the second driving force transmission direction changing unit 24 does not rotate. The loss of the driving force is only the portion where the pinions 66 and 68 and the side gear 72 rotate, so that the friction loss can be greatly reduced and the fuel consumption can be improved.

  FIG. 2 is an explanatory view showing an embodiment of the multi-plate clutch mechanism 30 of FIG. 1 in a skeleton diagram. In FIG. 2, the multi-plate clutch mechanism 30 is installed between a right rear wheel drive shaft 76 a connected to the side gear 72 of the rear wheel differential device 26 and a rear wheel drive shaft 76 b connected to the right rear wheel 82. It is separated from the rear wheel differential device 26 and is provided on the rear wheel drive shaft side. For this reason, the multi-plate clutch mechanism 30 of the present embodiment can use the conventional rear wheel differential device 26 as it is.

  The multi-plate clutch mechanism 30 includes an outer hub 86 for inputting the driving force of the right rear wheel drive shaft 76a from the rear wheel differential device 26, and an inner hub 84 connected to the rear wheel drive shaft 76b of the right rear wheel 82. The clutch plates are alternately arranged on each of them, and a piston 88 for adjusting the clutch fastening force is arranged on the right side of the clutch plate. The piston 88 is clutched by an actuator 90 such as a ball cam mechanism which will be clarified later. It is pushed to the plate side to adjust the clutch fastening force.

  FIG. 3 is an explanatory diagram showing a comparative example of a multi-plate clutch mechanism that realizes the same function as FIG. 2 in a skeleton diagram. The comparative example of FIG. 3 is characterized in that the multi-plate clutch mechanism 30 is integrated with the rear wheel differential device 26.

  In FIG. 3, the multi-plate clutch mechanism 30 is disposed between the ring gear 62 of the rear wheel differential device 26 and the storage cylinder 300 that transmits the rotation of the ring gear to the pinions 66 and 68. In other words, the rotation of the ring gear 62 is transmitted to the integrated outer hub 86 via the differential case 64, and the inner hub 84 is connected to the rotating shaft of the storage cylinder 300, and when the multi-plate clutch mechanism 30 is fastened, the ring gear The rotation of 62 rotates the storage cylinder 300 via the multi-plate clutch mechanism 30, thereby rotating the pinions 66 and 68, and transmitting the driving force to the right rear wheel 80 and the left rear wheel 82 via the side gears 70 and 72. To do.

  Even in the comparative example shown in FIG. 3, when the multi-plate clutch mechanism 30 is disconnected together with the disconnection / connection device 28 shown in FIG. 1 in the two-wheel drive mode, the first driving force transmission direction change shown in FIG. The rotation of the rear wheel drive system between the bevel gear 52 of the unit 20 and the drive pinion 60 of the second driving force transmission direction changing unit 24 can be stopped.

  However, in the comparative example shown in FIG. 3, since the multi-plate clutch mechanism 30 is provided integrally with the rear wheel differential device 26, the conventional rear wheel differential device cannot be applied as it is. It is necessary to construct a new device in which the rear wheel differential device 26 and the multi-plate clutch mechanism 30 are integrated. As a result, the structure becomes complicated.

  Further, since the multi-plate clutch mechanism 30 is disposed between the second driving force transmission direction conversion unit 24 on the driving force input side and the rear wheel differential device 26, the second driving force transmission direction conversion unit 24 is used as a clutch torque capacity. Therefore, the clutch torque capacity of about 2 to 3 times, for example, is required, and the multi-plate clutch mechanism 30 is increased in size, resulting in an increase in weight and an increase in cost.

  Further, since the rear wheel differential 26 and the multi-plate clutch mechanism 30 are disposed in the same casing in which the differential case 64 and the outer hub 86 are integrated, the lubricating oil for the rear wheel differential 26 and the lubricating oil for the multi-plate clutch mechanism 30 are provided. Are used with different performances, but a lubricating oil separation structure is required so that both lubricating oils are not mixed, which further complicates the structure.

  On the other hand, the multi-plate clutch mechanism 30 of the present embodiment shown in FIG. 2 is provided on the rear wheel drive shaft between the rear wheel differential device 26 and, for example, the right rear wheel 82. The transmission torque is distributed in the differential device 26, so that the clutch torque capacity of the multi-plate clutch mechanism 30 is halved compared to the comparative example of FIG. 3, and the multi-plate clutch mechanism 30 is reduced in size and weight. Therefore, the cost can be reduced. Further, since the multi-plate clutch mechanism 30 can be provided as a separate device, the conventional rear wheel differential device 26 can be applied as it is, and thereby the cost for constructing the driving force distribution device 10 of the present embodiment. Can be reduced.

  FIG. 4 is a cross-sectional view showing an embodiment of a multi-plate clutch mechanism used in the present invention. In FIG. 4, the multi-plate clutch mechanism 30 is installed between a right rear wheel drive shaft 76a inputted from the rear wheel differential device 26 side and a right rear wheel drive shaft 76b connected to the right rear wheel. In the following description, the right rear wheel drive shaft 76a will be described as an input drive shaft and the right rear wheel drive shaft 76b will be described as an output drive shaft as necessary.

  The multi-plate clutch mechanism 30 has an inner hub 84 fixed to the right shaft end of the input drive shaft 76a by spline fitting, and an outer hub 86 fixed to the left shaft end of the output drive shaft 76b is disposed outside the multi-plate clutch mechanism 30. A plurality of clutch plates fitted in the inner hub 84 and the outer hub 86 are alternately arranged.

  The connection / disconnection of the multi-plate clutch mechanism 30 and the adjustment of the fastening force are performed by a ball cam mechanism 92 provided on the left side. In the ball cam mechanism 92, a piston 88 is disposed on the left side of the clutch plate of the multi-plate clutch mechanism 30 so as to be slidable in the axial direction, and a rotating cam plate 102 and a fixed cam plate 106 are disposed on the left side of the piston 88 via a thrust bearing 110. However, a ball 104 is interposed between the two.

  The balls 104 are fitted in cam grooves formed in the circumferential direction on the opposing surfaces of the fixed cam plate 106 and the rotating cam plate 102. The cam groove in the circumferential direction is deepest when the illustrated ball 104 is sandwiched, and the cam groove becomes shallower in the circumferential direction.

  For this reason, when the rotating cam plate 102 is rotated by the actuator by the engagement of the pinion gear with the fan-shaped gear provided on the distal end side of the arm portion 102a extending below the rotating cam plate 102, the depth is reduced. The ball 104 moves the rotating cam plate 102 to the right side by the movement of the changing cam groove, advances the piston 88 to the multi-plate clutch mechanism 30 side, and presses the clutch plate, thereby generating a clutch fastening force. The reaction force accompanying the movement of the piston 88 due to the rotation of the rotating cam plate 102 is received by the fixed plate 108 via the thrust bearing 112.

  An oil pump 94 is disposed on the left side of the ball cam mechanism 92. The oil pump 94 includes an inner gear 116 that functions as a rotor and an outer gear 118 that functions as a stator. The inner gear 116 is fixed to an input drive shaft 76 a that is connected to a side gear 72 of the rear wheel differential device 26. The gear 118 is sandwiched and fixed between the inner wall of the casing 101 and a fixing plate 115 fixed with bolts.

  In the oil pump 94, the number of inner teeth of the outer gear 118 is increased by one to n + 1 with respect to the number of gears n of the inner gear 116, and the inner gear 116 is connected coaxially to the input drive shaft 76a. In addition, the rotation of the inner gear 116 with respect to the outer gear 118 that is eccentrically arranged with respect to the inner gear 116 realizes a pumping action that sucks and discharges oil.

  The oil pump 94 sucks and discharges the oil accumulated in the casing 101, and discharges the lubricating oil from the discharge passage 125 to the oil chamber 120 formed in the direction of the internal axis of the input drive shaft 76a. The lubricating oil discharged to the oil chamber 120 is supplied between the clutch plates from the inner hub 84 side in the multi-plate clutch mechanism 30 through the oil supply hole 122, and generates heat due to frictional contact of the clutch plates when adjusting the fastening force. Cooling and lubrication.

  Supply of lubricating oil to the multi-plate clutch mechanism 30 is necessary when the multi-plate clutch mechanism 30 is fastened or the fastening force is adjusted in the four-wheel drive mode. In the two-wheel drive mode, the multi-plate clutch mechanism 30 is supplied. In the two-wheel drive mode, lubrication oil is supplied to the multi-plate clutch mechanism 30 in order to eliminate drag torque for stopping the rear wheel drive system from the bevel gear 52 to the drive pinion 60 shown in FIG. Do not do. The supply of lubricating oil to the multi-plate clutch mechanism 30 in the four-wheel drive mode and the supply stop of lubricating oil in the two-wheel drive mode will be clarified further in the following description.

  FIG. 5 is an explanatory view showing an attachment state of a spring member for securing a space in the multi-plate clutch mechanism of FIG.

  In FIG. 5, the multi-plate clutch mechanism 30 engages the inner side of the clutch plate 98 with the inner hub 84, engages the outer side of the clutch plate 100 with the outer hub 86, and alternately arranges the clutch plates 98 and 100. ing.

  In the arrangement state of the clutch plates 98, 100, in the two-wheel drive mode, the piston 88 is in the retracted release position where the piston 88 is retracted. In order to eliminate the generation of drag torque due to the contact of the clutch plates 98, 100 at this time, In the embodiment, the clutch spacer spring 130 is disposed on the inner side of the clutch plates 98 and 100, and the clutch plates 98 and 100 are widened by the clutch spacer spring 130 in a state where the clutch is disengaged. This eliminates the generation of friction torque.

  FIG. 6 is an exploded view showing the attachment structure of the spring member to the clutch plate of FIG. A spacer housing portion 134 is formed on the inner side of the clutch plate 100 disposed on the outer hub 86 side, and a clutch spacer spring 130 is fitted therein, and the clutch spacer spring 130 is bent at both sides of the sandwiching portion 130a. The spring pieces 130b and 130c are formed so as to widen the space between the opposing clutch plates 98 to ensure a certain distance.

  Referring to FIG. 5 again, a piston spacer spring 132 is disposed between the piston 88 of the ball cam mechanism 32 for adjusting the fastening force of the multi-plate clutch mechanism 30 and the inner hub 84 to disengage the clutch in the two-wheel drive mode. In order to avoid contact between the clutch plates of the multi-plate clutch mechanism 30 in a state, a constant interval is secured between them. As the piston spacer spring 132, for example, a coil spring is used.

  With the arrangement of the clutch spacer spring 130 and the piston spacer spring 132 in the multi-plate clutch mechanism 30 shown in FIG. 5, the drag torque that reduces the generation of drag torque in the two-wheel drive mode to almost zero when the supply of lubricant is stopped. A reduction mechanism is configured.

  FIG. 7 is an explanatory diagram showing, in a skeleton diagram, an embodiment of the lubricating oil mechanism provided in the multi-plate clutch mechanism of the present invention. FIG. 7 (A) shows the four-wheel drive mode, and FIG. The wheel drive mode is shown.

  7A, the multi-plate clutch mechanism 30 is in the engaged state, and the driving force from the propeller shaft 22 is applied from the drive pinion 60 to the ring gear 62 of the rear wheel differential device 26. The left rear wheel 80 and the right rear wheel are input via the pinion 66, 68 and the side gears 70, 72 and the left rear wheel drive shaft 74 and the right rear wheel drive shafts 76a, 76b fastened by the multi-plate clutch mechanism 30. It is transmitted to the wheel 82 and the driving force is transmitted to the road surface.

  The oil pump 94 provided in the multi-plate clutch mechanism 30 rotates with the right rear wheel drive shaft 76a connected to the side gear 72 of the rear wheel differential device 26 as an input drive shaft, and oil outside the casing of the multi-plate clutch mechanism 30. And the lubricating oil is supplied between the clutch plates.

  In the four-wheel drive mode, the left rear wheel drive shaft 74 and the right rear wheel drive shafts 76a and 76b are all rotated forward as indicated by an arrow A because the multi-plate clutch mechanism 30 is in the engaged state. It is rotating in the direction.

  FIG. 8A shows an end view of the oil pump 94 in the four-wheel drive mode. The oil pump 94 includes an inner gear 116 that operates as a rotor coaxially disposed with the input drive shaft 76a from the rear wheel differential device 26, and an outer gear 118 that is eccentrically disposed on the casing side and rotatably supported. While the number of gears of the inner gear 116 is 6, the number of inner teeth of the outer gear 118 is 7, which is one more than that.

  In the four-wheel drive mode, the inner gear 116 of the oil pump 94 is normally rotated in the rotation direction indicated by the arrow A by the input drive shaft 76a, and the strainer 140 for sucking the lubricating oil in the casing is on the lower side. The oil sucked from the suction port 141 is discharged from the upper discharge port 142, and the lubricating oil is supplied to the clutch plate portion of the multi-plate clutch mechanism.

  In the two-wheel drive mode of FIG. 7B, the multi-plate clutch mechanism 30 is in the disengaged state, and the input is obtained by connecting the right rear wheel drive shaft 76b of the right rear wheel 82 and the side gear 72 of the rear wheel differential device 26. The right rear wheel drive shaft 76a as the drive shaft is disconnected. For this reason, the rotation of the right rear wheel 82 is not transmitted to the side gear 72. Therefore, rotation of the side gear 70 by the left rear wheel 80 rotates the side gear 72 in the opposite direction via the pinions 66 and 68.

  That is, in the two-wheel drive mode, the left rear wheel drive shaft 74 and the right rear wheel drive shaft 76b on the right rear wheel 82 side separated by the multi-plate clutch mechanism 30 are rotated forward as indicated by an arrow A. However, the right rear wheel drive shaft 76a connected to the side gear 72 provided with the oil pump 94 is reversely rotated as indicated by an arrow B.

  Thus, when the rotation of the input drive shaft with respect to the oil pump 94 is reversed in the two-wheel drive mode, the upper side of the oil pump 94 becomes the suction port 136 and is connected to the strainer 140 as shown in FIG. The lower side becomes the discharge port 138. For this reason, since the suction port 136 side is connected to the lubricating oil flow path of the clutch plate in the multi-plate clutch mechanism 30, oil cannot be sucked from this lubricating oil flow path. The supply of lubricating oil to the multi-plate clutch mechanism 30 by the oil pump 94 is stopped.

  Thus, in the two-wheel drive mode, the supply of the lubricating oil to the multi-plate clutch mechanism 30 is stopped by the reverse rotation of the oil pump 94, and the lubricating oil is not supplied between the clutch plates in the clutch disengaged state. The drag torque due to friction loss due to the agitation can be made substantially zero.

  By the way, as shown in FIGS. 7B and 8B, when the oil pump 94 is reversely rotated in the two-wheel drive mode, the lubricating oil cannot be sucked, resulting in a shortage of lubricating oil inside the oil pump 94. become. When the oil pump 94 itself runs out of lubricating oil, as shown in FIG. 4, the pump gear rotating in contact with the inner wall surface of the casing 101 and the plate surface of the fixed plate 115 is seized due to the lack of lubricating oil. there is a possibility.

  Therefore, in the present embodiment, an anti-seizure treatment layer is formed on the sliding contact surfaces of the outer gear 118 and the inner gear 116 provided on the oil pump 94 with a surface treatment such as plating or DLC coating. Yes. As a result, even if the oil pump 94 cannot reversely rotate due to the reverse rotation of the oil pump 94 in the two-wheel drive mode and the oil pump 94 itself causes a shortage of lubricating oil, a seizure prevention treatment layer is formed on the sliding surface of the pump gear. As a result, seizure due to lack of lubricating oil can be reliably prevented.

  FIG. 9 is an explanatory view showing another embodiment of a lubricating oil supply mechanism using a one-way clutch as an oil pump in a skeleton diagram. FIG. 9A shows a four-wheel drive mode, and FIG. Shows the two-wheel drive mode.

  Taking the four-wheel drive mode in FIG. 9A as an example, the oil pump 94 disposed on the left side of the multi-plate clutch mechanism 30 is connected to the side gear 72 of the rear wheel differential device 26 to the right as an input drive shaft. An inner gear is attached to the rear wheel drive shaft 76a via a one-way clutch 144.

  The one-way clutch 144 operates to rotate the inner gear of the oil pump 94 with respect to the forward rotation of the right rear wheel drive shaft 76a in the direction of arrow A by the side gear 72, and the one-way clutch 144 is connected to the reverse rotation. Is released and only the one-way clutch 144 is idling.

  For this reason, in the four-wheel drive mode of FIG. 9A, the driving force from the propeller shaft 22 is input to the rear wheel differential device 26, and the multi-plate clutch mechanism 30 is in the engaged state. The rotation of 62 is transmitted to the left rear wheel 80 via the pinions 66 and 68 and the side gears 70 and 72 and to the right rear wheel 82 via the multi-plate clutch mechanism 30 in the engaged state, and transmits the driving force to the road surface.

  For this reason, in the four-wheel drive mode, both the left front wheel drive shaft 74 and the right rear wheel drive shafts 76a and 76b are normally rotated as indicated by the arrow A, and the right rear wheel drive shaft 76a connected to the side gear 72 is By the normal rotation, the one-way clutch 144 performs a clutch operation, rotates the inner gear of the oil pump 94, and can supply lubricating oil to the multi-plate clutch mechanism 30.

  FIG. 9B shows the two-wheel drive mode, and the multi-plate clutch mechanism 30 is in the disengaged state, so that the connection between the side gear 72 and the right rear wheel 82 of the rear wheel differential device 26 is disconnected. For this reason, the forward rotation indicated by the arrow A by the right rear wheel drive shaft 76b of the right rear wheel 82 is not transmitted to the side gear 72 of the rear wheel differential 26.

  The rotation of the side gear 70 due to the forward rotation indicated by the arrow A of the left front wheel drive shaft 74 by the left rear wheel 80 is transmitted to the side gear 72 via the pinions 66 and 68, and the side gear 72 is driven as shown by the arrow B. The shaft 76a is rotated in the reverse direction. Due to the reverse rotation of the right rear wheel drive shaft 76a, the one-way clutch 144 rotates idly without rotating the inner gear of the oil pump 94. As a result, in the two-wheel drive mode, the supply of lubricating oil to the multi-plate clutch mechanism 30 is stopped without the oil pump 94 being rotated.

  FIG. 10 is a hydraulic circuit diagram showing another embodiment of the lubricating oil supply mechanism in the multi-plate clutch mechanism that switches the path of the oil pump by a check valve. In FIG. 10, as shown in FIGS. 7 and 9, the oil pump 94 rotates in the forward direction in the four-wheel drive mode, and rotates in the reverse direction in the two-wheel drive mode. Here, the discharge port of the oil pump 94 is indicated by a port 95a and a black triangle during forward rotation, and is indicated by a port 95b and a white triangle during reverse rotation.

  First, when the oil pump 94 rotates reversely in the two-wheel drive mode, the oil pump 94 causes the oil in the casing 101 to flow from the strainer 140 to the port 95a via the first suction path check valve 146 provided in the first suction path 146a. And the lubricating oil is supplied from the port 95b through the first discharge path check valve 148 provided in the first discharge path 148a to the portion other than the multi-plate clutch mechanism through the path indicated by the arrow A. During the forward rotation of the pump 94, the supply of lubricating oil to the multi-plate clutch mechanism is stopped.

  On the other hand, when the oil pump 94 in the four-wheel drive mode rotates forward, the oil pump 94 removes oil in the casing 101 from the strainer 140 via the second suction path check valve 150 provided in the second suction path 150a. The oil is sucked into the port 95b, and lubricating oil is supplied from the port 95a to the multi-plate clutch mechanism through a second discharge path check valve 152 provided in the second discharge path 152a through a path indicated by an arrow B.

  Thus, by providing a switching circuit with four check valves for the oil pump 94 that rotates in reverse in the two-wheel drive mode and rotates in the four-wheel drive mode, lubricating oil is supplied to the multi-plate clutch mechanism in the four-wheel drive mode. In the two-wheel drive mode, the supply of lubricating oil to the multi-plate clutch mechanism can be stopped to make the drag torque almost zero.

  FIG. 11 is a hydraulic circuit diagram showing another embodiment of the lubricating oil supply mechanism that switches the path of the oil pump by the check valve. Compared with the embodiment in which the four check valves in FIG. 10 are provided, two check valves are used. It is characterized by being able to finish.

  In FIG. 11, when the oil pump 94 reversely rotates in the two-wheel drive mode, the oil in the casing 101 is sucked into the port 95a from the strainer 140 through the suction path check valve 158 provided in the suction path 158a. A circulation loop indicated by an arrow A is formed to return oil from the port 95b to the casing 101 through the discharge / suction passage 156, and lubricating oil is supplied from the oil pump 94 to other parts including the multi-plate clutch mechanism. Not.

  On the other hand, in the four-wheel drive mode, the oil pump 94 rotates in the forward direction, and the oil in the casing 101 is sucked into the port 95b from the strainer 140 through the discharge and suction passage 156, discharged from the port 95a, and discharged to the discharge passage 154a. Lubricating oil is supplied to the multi-plate clutch mechanism through a path indicated by an arrow B via the provided discharge path check valve 154.

  That is, in the forward rotation of the oil pump 94 in the four-wheel drive mode, the oil is circulated as indicated by the arrow A, the lubricating oil is not supplied to the multi-plate clutch mechanism, and the drag torque of the multi-plate clutch mechanism by the lubricating oil is increased. Can be almost zero. On the other hand, in the forward rotation of the oil pump 94 in the four-wheel drive mode, the lubricating oil is supplied to the multi-plate clutch mechanism through the lubricating path indicated by the arrow B, and the clutch plate is lubricated when adjusting the clutch fastening force. Cooling can be performed appropriately.

  FIG. 12 is a cross-sectional view showing an embodiment of a multi-plate clutch mechanism provided with a lubricating oil supply mechanism that opens and closes a lubricating path in conjunction with a piston that adjusts the clutch fastening force.

  In FIG. 12, the multi-plate clutch mechanism 30 is housed in a casing 101 connected to a casing 27 on the rear wheel differential device 26 side, and an input drive shaft 76a from the rear wheel differential device 26 and the right rear wheel side. To the right rear wheel drive shaft 76b. The multi-plate clutch mechanism 30 can adjust the fastening force by moving the piston 88 in the right direction by the ball cam mechanism 92 disposed on the left side.

  The ball cam mechanism 92 includes a rotating cam plate 102, a ball 104, and a fixed cam plate 106. In this embodiment, the rotating cam plate 102 uses a rotating cam plate gear having a gear formed on the outer periphery. .

  Adjustment of the fastening force of the multi-plate clutch mechanism 30 by the ball cam mechanism 92 is performed by a servo motor 164 disposed on the lower side of the casing 101. The rotation of the servo motor 164 is decelerated by the speed reducer 166, and then the gear 170 provided on the drive shaft 168 is rotated. The rotation of the gear 170 is transmitted to the rotating cam plate gear 102 via the gears 172, 174, and 176, A change in position of the ball 104 relative to the cam groove with the rotation of the rotating cam plate gear 102 moves the rotating cam plate 102 in the right direction. Is adjusted.

  In the present embodiment, the oil pump 94 is arranged so as to rotate on the right rear wheel drive shaft 76b connected to the right rear wheel on the right side of the multi-plate clutch mechanism 30. That is, in the oil pump 94, the inner gear 116 is coaxially fixed to the right rear wheel drive shaft 76b, and the outer gear 118 is rotatably supported by sandwiching the inner wall of the casing and the fixing plate 115 at an eccentric position on the outer side.

  In this embodiment, as a lubricating oil supply mechanism from the oil pump 94, the oil path inside the right rear wheel drive shaft 76b that rotates the oil pump 94 is connected to the rear wheel differential device 26. Lubricating oil is supplied to the valve chamber 160 from an oil pump 94 in communication with a stepped cylindrical valve chamber 160 formed in the direction of the internal axis of the input drive shaft 76a.

  A valve member 162 is incorporated in the valve chamber 160 so as to be movable in the axial direction, and a port 182 is provided at a position of the valve member 160 facing the multi-plate clutch mechanism 30. As will be apparent from the following description, the valve member 162 moves in the axial direction in conjunction with the piston 88 operated by the ball cam mechanism 92, thereby causing the port 182 to move relative to the oil supply hole on the multi-plate clutch mechanism 30 side. The supply of lubricant is stopped by opening and closing.

  Here, the upper side of the center line in FIG. 12 shows the operation state in the two-wheel drive mode in which the piston 88 moves backward and the multi-plate clutch mechanism 30 is disconnected, while the lower side of the center line shows the ball cam mechanism. The operation state in the four-wheel drive mode in which the piston 88 is moved by 92 and the multi-plate clutch mechanism 30 is engaged is shown.

  FIG. 13 is a cross-sectional view showing a part in the clutch disengaged state on the upper side of the center line in the multi-plate clutch mechanism of FIG. The clutch disengaged state in FIG. 13 is an operating state in the two-wheel drive mode, and the piston 88 is returned to the retracted position where the press of the clutch plate of the multi-plate clutch mechanism 30 is released by the ball cam mechanism 92.

  A connection pin 178 is connected to the piston 88 from the radial direction through the elongated hole 184 of the input drive shaft 76a with the tip end fitted to the valve member 162. For this reason, the valve member 162 accommodated in the valve chamber 160 can be moved in the axial direction in conjunction with the movement of the piston 88 by the ball cam mechanism 92.

  An oil supply hole 122 is provided at a position corresponding to the multi-plate clutch mechanism 30 of the input drive shaft 76a in which the valve chamber 160 is formed. The oil supply hole 122 supplies lubricating oil between the oil hole of the inner hub 84 and the clutch plate. Supply.

  A port 182 is provided in the valve member 162 that is retracted via the connecting pin 178 at a position where the piston 88 is disengaged from the oil supply hole 122 on the input drive shaft 76a side. The oil supply hole 122 is disengaged in the disconnected state, the oil supply hole 122 is closed, and the supply of lubricating oil from the oil pump 94 to the multi-plate clutch mechanism 30 is stopped.

  A retaining ring 125 is provided on the right side of the valve chamber 160 to restrict the movement position of the valve member 162. Further, a needle bearing 128 is interposed between the coaxial fitting portions at the tips of the input drive shaft 76a and the right rear wheel drive shaft 76b to enable relative rotation.

  Thus, in the two-wheel drive mode shown in FIG. 13, the multi-plate clutch mechanism 30 is disengaged by the retraction of the piston 88 by the ball cam mechanism 92, and the movement of the piston 88 is caused by the connecting pin 178. The valve member 162 housed in the valve chamber 160 is moved to the retracted position on the right side, thereby eliminating the communication with the oil supply hole 122 of the port 182, and supplying oil between the clutch plates of the multi-plate clutch mechanism 30 by the oil pump 94. The drag torque when the clutch is disengaged is almost zero.

  FIG. 14 is a cross-sectional view showing a portion of the multi-plate clutch mechanism shown in FIG.

  In FIG. 14, in the four-wheel drive mode, the rotation of the rotating cam plate gear 102 of the ball cam mechanism 92 causes the ball 104 to move relative to the shallow portion of the circumferential groove, thereby rotating the rotating cam as shown in the figure. The plate gear 102 is moved in the right direction, and along with this, the piston 88 is pushed to the right side through the thrust bearing, thereby pressing the clutch plate of the multi-plate clutch mechanism 30 to be in the engaged state.

  As the piston 88 moves in the right direction, the valve member 162 also moves in the right direction via the connecting pin 178, and the port 182 provided in the valve member 162 is provided in the input drive shaft 76a to which the inner hub 84 is fixed. The oil supply hole 122 communicates with the oil supply hole 122 to open the flow path, and the lubricating oil from the oil pump 94 is supplied between the clutch plates of the multi-plate clutch mechanism 30 in the engaged state to perform lubrication cooling by frictional contact of the clutch plates.

  FIG. 15 is a cross-sectional view showing an embodiment of a multi-plate clutch mechanism provided with a lubricating oil supply mechanism that opens and closes a lubricating path by utilizing the difference in the rotation direction of the input / output drive shaft.

  In FIG. 15, the multi-plate clutch mechanism 30 is housed in a casing 101 separated from a rear wheel differential device arranged on the left side, and an input drive shaft 76a for inputting a driving force from the rear wheel differential device; It is arranged between the output drive shaft 76b connected to the right rear wheel, and the ball cam mechanism 92 adjusts the connection and fastening force.

  As in the embodiment of FIG. 12, the ball cam mechanism 92 decelerates the rotation from the servo motor 164 by the speed reducer 166, moves the piston 88 by rotating the rotating cam plate gear via the gear train, and the clutch engagement force To adjust.

  The oil pump 94 is provided on the output drive shaft 76b side. Therefore, in both the two-wheel drive mode and the four-wheel drive mode, the oil pump 94 rotates in the positive direction indicated by the arrow A and can always discharge the lubricating oil. The discharge side of the lubricating oil from the oil pump 94 is supplied to an oil chamber 185 that is a stepped cylindrical hole formed in the direction of the internal axis of the input drive shaft 76a via a communication path in the output drive shaft 76b. On the outer peripheral side of the oil chamber 185, an oil supply hole 122 for supplying lubricating oil between the clutch plates of the multi-plate clutch mechanism 30 is formed in addition to an oil supply hole for lubricating oil for the ball cam mechanism 92.

  The supply of the lubricating oil in the four-wheel drive mode of the lubricating oil supply mechanism in FIG. 15 and the stop of the supply of the lubricating oil in the two-wheel drive mode are performed on the outer peripheral spline provided on the outer periphery of the right shaft end of the input drive shaft 76a. Difference in rotation direction between forward rotation of the arrow A of the input drive shaft 76 in the four-wheel drive mode and reverse rotation of the arrow B in the two-wheel drive mode with respect to spline fitting with the inner peripheral spline of the inner hub 84 to be fitted. To switch oil supply.

  FIG. 16 shows a part of the shaft section of the input drive shaft 76a and the inner hub 84 in a portion where the oil supply hole 122 of FIG. 15 is formed. FIG. 16A shows the operating state in the four-wheel drive mode.

  In FIG. 16A, an outer peripheral spline 186 is formed on the outer periphery of the input drive shaft 76a, and the outer peripheral spline 186 has a circumferential length of the valley portion 186b with respect to a circumferential length of the peak portion 186a. Is getting longer.

  An inner peripheral spline 188 is formed on the inner hub 84 disposed outside the input drive shaft 76a. The inner circumferential spline 188 is formed such that the circumferential length of the valley portion 188b is the same as the circumferential length of the peak portion 188a.

  For this reason, when the rotation direction changes, the input drive shaft 76a and the inner hub 84 move relative to each other by the gap in the circumferential direction of the outer peripheral spline 188, thereby switching the lubricating oil supply path.

  In the four-wheel drive mode of FIG. 16A, the input drive shaft 76a receives the drive force and transmits the drive force to the inner hub 84, and the input drive shaft 76a rotates in the forward direction indicated by the arrow A. The crest 186a of the inner peripheral spline 186 moves to and contacts the right side of the crest 188a of the inner peripheral spline 188 of the inner hub 84, whereby the inner hub 84 is integrated with the input drive shaft 76a in the direction of arrow a. Has been rotated.

  In this state, the oil supply hole 122 provided in the radial direction of the input drive shaft 76a is opposed to the oil supply hole 190 provided in the valley portion 188b of the inner hub 84, and the inside of the input drive shaft 76a. The oil from the oil pump 94 supplied to the oil chamber 185 passes through the oil supply holes 122 and 190 located at the opposite open positions, and supplies lubricating oil between the clutch plates of the multi-plate clutch mechanism.

  FIG. 16B shows a switching state in the two-wheel drive mode. In the two-wheel drive mode, since the multi-plate clutch mechanism 30 is disengaged, the rotation of the left rear wheel is transmitted to the input drive shaft 76a via the rear wheel differential, and the input drive shaft 76a is indicated by an arrow B. The reverse rotation is shown. Against this reverse rotation, the input drive shaft 76a is on the driving side, and the peak 186a of the inner peripheral spline 186 is in contact with the right side of the peak 188a of the inner peripheral spline 188 of the inner hub 84. Rotate inner hub 84 in the direction.

  Therefore, when the input drive shaft 76a rotates in reverse in the two-wheel drive mode, the oil supply hole 122 of the input drive shaft 76a is closed by the peak portion 188a of the inner peripheral spline 188 of the inner hub 84, and the oil supply hole Since the communication with 190 is interrupted, the supply of lubricating oil from the oil pump to the multi-plate clutch mechanism is stopped, and the drag torque in the multi-plate clutch mechanism can be made substantially zero.

  FIG. 17 is a graph showing the change in drag torque with respect to the rotational speed of the multi-plate clutch mechanism when the supply of lubricating oil is stopped in the two-wheel drive mode, in comparison with the conventional example.

  In FIG. 17, a characteristic 192 is a change in drag torque with respect to the rotation speed when the supply of the lubricating oil is stopped in the two-wheel drive mode according to the present embodiment, and can be maintained substantially near zero. On the other hand, in the conventional characteristic 194 in which the lubricating oil was supplied, a large drag torque having a peak near 1000 rotations and substantially stabilized after decreasing with respect to the increase in rotation is generated. It has been confirmed that the drag torque is sufficiently reduced by stopping.

  As a structure for reducing the drag torque in the multi-plate clutch mechanism, in addition to stopping the supply of the lubricating oil, the spacer spring for securing the gap between the piston and the clutch plate shown in FIG. The same applies to other embodiments other than the embodiment of FIG.

Further, the present invention includes appropriate modifications that do not impair the object and advantages thereof, and is not limited by the numerical values shown in the above embodiments.

10: Driving force transmission device 12: Four-wheel drive vehicle 14: Engine 16: Transmission 18: Front wheel differential device 20: First driving force transmission direction conversion unit 22: Propeller shaft 24: Second driving force transmission direction conversion unit 25 : ECU
26: rear wheel differential device 27: casing 28: connecting / disconnecting device 30: multi-plate clutch mechanism 32, 60: drive pinion 34, 62: ring gear 35, 64: differential case 36, 38, 66, 68: pinion 40, 42 , 70, 72: Side gear 44: Left front wheel drive shaft 46: Right front wheel drive shaft 48: Left front wheel 50: Right front wheel 52: Bevel gear 54: Output pinion 56, 58: Universal joint 74: Left rear wheel drive shafts 76a, 76b: Right rear wheel drive shaft 80: Left rear wheel 82: Right rear wheel 84: Inner hub 86: Outer hub 88: Piston 90: Actuator 92: Ball cam mechanism 94: Oil pump 98, 100: Clutch plate 101: Casing 102: Rotating cam Plate gear 104: Ball 106: Fixed cam plate 108: Fixed plate 110, 112: Thrust bearing 11 : Inner gear 118: Outer gear 120: Oil chamber 122, 190: Oil supply holes 124 and 126: Ball bearing 128: Needle bearing 130: Clutch spacer spring 132: Piston spacer spring 134: Spacer storage portions 136 and 141: Suction port 138 142: Discharge port 140: Strainer 144: One-way clutch 146: First suction path check valve 148: First discharge path check valve 150: Second suction path check valve 152: Second discharge path check valve 154: Discharge path check valve 156: Discharge combined suction path 158: Suction path check valve 160: Valve chamber 162: Valve member 164: Servo motor 166: Reducer 168: Drive shaft 170, 172, 174, 176: Gear 178: Connection pin 182: Port 184: Slot 185: Oil chamber 186: Outer circumference Spline 188: inner peripheral spline 300: receiving cylinder

Claims (14)

A four-wheel drive vehicle that can switch between a four-wheel drive mode that automatically controls the distribution of the driving force transmitted to the front wheels and the rear transportation according to the driving conditions, and a two-wheel drive mode that transmits the driving force only to the front transportation. In the driving force transmission device for
A front wheel differential device that receives driving force from the engine and distributes the driving force to the left and right front wheels;
A first driving force transmission direction conversion unit that changes the rotation direction of the driving force from the engine and transmits the driving force to the rear transportation;
Receiving a driving force from the first driving force transmission direction conversion unit, changing a rotation direction, and transmitting to the rear trans-differential device, a second driving force transmission direction conversion unit;
A differential device for rear transportation that distributes the driving force to the left and right rear wheels, and a connecting / disconnecting device that connects / disconnects the driving force to the first driving force transmission direction changing portion;
A multi-plate clutch mechanism that is provided between one of the outputs of the rear differential and one of the left and right rear wheels, and is capable of continuously adjusting the fastening force;
The drag torque when the engagement of the multi-plate clutch mechanism is released is set to be smaller than the friction torque between the first driving force transmission direction converting portion and the second driving force transmitting direction converting portion. A drag torque reduction mechanism;
In the two-wheel drive mode, the connecting / disconnecting device is disconnected and the multi-plate clutch mechanism is released to stop the rotation of the second driving force transmission direction changing portion from the first driving force transmission direction changing portion. A controller that couples the connecting / disconnecting device in the four-wheel drive mode and adjusts the fastening force of the multi-plate clutch mechanism according to the running condition of the vehicle;
A driving force transmission device for a four-wheel drive vehicle.
2. The driving force transmission device for a four-wheel drive vehicle according to claim 1, wherein the rear wheel differential device and the multi-plate are arranged so that the lubricating oil of the rear wheel differential device and the lubricating oil of the multi-plate clutch mechanism are not mixed. A driving force transmission device for a four-wheel drive vehicle, comprising a structure for separating the clutch mechanism into a separate chamber.
2. The driving force transmission device for a four-wheel drive vehicle according to claim 1, wherein the drag torque reduction mechanism takes a clearance of the clutch plate wider than a predetermined value in a two-wheel drive mode in which the multi-plate clutch mechanism is disconnected. 4. A lubricating oil supply mechanism that stops or restricts the supply of lubricating oil to the clutch plate and supplies the lubricating oil to the clutch plate in the four-wheel drive mode in which the multi-plate clutch mechanism is fastened is provided. Driving force transmission device for wheel drive vehicles.
4. The driving force transmission device for a four-wheel drive vehicle according to claim 3, wherein the lubricating oil supply mechanism rotates reversely in the two-wheel drive mode and rotates forward in the four-wheel drive mode. A driving force transmission device for a four-wheel drive vehicle, comprising an oil pump driven by a shaft.
5. The driving force transmission device for a four-wheel drive vehicle according to claim 4, wherein the oil pump is a gear pump, and an anti-seizure treatment layer is formed on a sliding contact surface with the housing of the gear pump. Driving force transmission device for wheel drive vehicles.
5. The driving force transmission device for a four-wheel drive vehicle according to claim 4, wherein the oil pump is driven via a one-way clutch provided between an output shaft of the rear wheel differential device,
In the two-wheel drive mode, the one-way clutch is idled to stop the supply of lubricant to the multi-plate clutch mechanism, and in the four-wheel drive mode, the oil pump is rotated forward to supply lubricant to the multi-plate clutch mechanism. A driving force transmission device for a four-wheel drive vehicle.
The drive force transmission device for a four-wheel drive vehicle according to claim 1, wherein the lubricating oil supply mechanism includes:
An oil pump driven by an output shaft of a rear trans-differential device that rotates reversely in the two-wheel drive mode and rotates forward in the four-wheel drive mode;
A first suction path check valve that causes the oil pump to suck oil from a first suction path when the two-wheel drive mode is reversed;
A first discharge path check valve that discharges oil discharged from the oil pump to a portion other than the multi-plate clutch mechanism when reversing the two-wheel drive mode;
A second suction path check valve that causes the oil pump to suck oil from a second suction path during forward rotation in the four-wheel drive mode;
A second discharge path check valve that causes the multi-plate clutch mechanism to discharge oil discharged from the oil pump during forward rotation in the four-wheel drive mode;
A driving force transmission device for a four-wheel drive vehicle.
The drive force transmission device for a four-wheel drive vehicle according to claim 1, wherein the lubricating oil supply mechanism includes:
An oil pump driven by an output shaft of a rear trans-differential device that rotates reversely in the two-wheel drive mode and rotates forward in the four-wheel drive mode;
A suction path check valve that causes oil to be sucked into the oil pump from the first suction path when the two-wheel drive mode is reversed, and discharged into the tank through the discharge and suction path;
A discharge path check valve that causes the multi-plate clutch mechanism to discharge oil sucked into the oil pump from a discharge combined suction path during normal rotation in the four-wheel drive mode;
A driving force transmission device for a four-wheel drive vehicle.
The drive power transmission device for a four-wheel drive vehicle according to claim 3, wherein the lubricating oil supply mechanism is
An oil pump driven on the output side of the multi-plate clutch mechanism;
An opening and closing mechanism that stops the supply of lubricant by closing the lubrication path in the two-wheel drive mode, and supplies the lubricant by opening the lubrication path in the four-transmission drive mode;
A driving force transmission device for a four-wheel drive vehicle.
The drive force transmission device for a four-wheel drive vehicle according to claim 9, wherein the opening / closing mechanism comprises:
A valve chamber formed in the direction of the inner shaft of the output shaft from the rear wheel differential device in which the multi-plate clutch mechanism is disposed, and supplied with lubricating oil from an oil pump;
A valve member that is slidably housed in the valve chamber and moves in conjunction with an axially movable piston that connects and disconnects the clutch plate of the multi-plate clutch mechanism;
An oil supply hole for supplying lubricating oil between the clutch plates of the multi-plate clutch mechanism;
The movement of the valve member in conjunction with the movement of the piston to the clutch non-engagement position in the two-wheel drive mode closes the oil supply hole to shut off the lubricating oil, and the clutch plate of the piston in the four-wheel drive mode A drive force transmission device for a four-wheel drive vehicle that supplies the lubricating oil by opening the oil supply hole by the movement of the valve member in conjunction with the movement to the fastening position.
The drive force transmission device for a four-wheel drive vehicle according to claim 9, wherein the opening / closing mechanism comprises:
An oil chamber formed in the direction of the inner shaft of the output shaft of the rear wheel differential device and supplied with lubricating oil from the oil pump;
An outer peripheral spline having a wider valley than a peak formed on the outer periphery of the output shaft;
An inner hub of the multi-plate clutch mechanism in which an inner peripheral spline having a wider valley is formed with respect to a mountain that is fitted to the outer peripheral spline of the output shaft;
Lubricating oil for the multi-plate clutch mechanism is shut off at the contact position of the outer peripheral spline with the inner peripheral spline due to the reverse rotation of the output shaft in the two-wheel drive mode, and the outer periphery due to normal rotation of the output shaft in the four-wheel drive mode. A pair of oil supply holes formed in a valley portion of the outer peripheral spline and the inner peripheral spline for supplying lubricating oil to the multi-plate clutch mechanism at a contact position of the spline with the inner peripheral spline;
A driving force transmission device for a four-wheel drive vehicle.
5. The driving force transmission device for a four-wheel drive vehicle according to claim 4, wherein the drag torque reduction mechanism includes a spring member that urges the clutch plates in a direction of widening the interval between the clutch plates. Driving force transmission device for driving vehicles.
5. The driving force transmission device for a four-wheel drive vehicle according to claim 4, wherein the drag torque reduction mechanism includes a spring member that urges the clutch plate in a direction of widening a mutual gap between the drag torque reduction mechanism and the piston that presses the clutch plate. A driving force transmission device for a four-wheel drive vehicle.
  2. The driving force transmission device for a four-wheel drive vehicle according to claim 1, wherein the controller switches the connection / disconnection from the two-transmission driving mode to the four-transmission driving mode after the multi-plate clutch mechanism is engaged. The driving force for a four-wheel drive vehicle is characterized in that the device is fastened and the switching from the four-wheel drive mode to the two-transport mode is performed by disengaging the connecting / disconnecting device after opening the multi-plate clutch mechanism. Transmission device.

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