DRIVING-FORCE TRANSMITTING APPARATUS FOR FOUR-WHEEL-DRIVE VEHICLE

• US 20100274456A1
• Filed: 04/19/2010
• Published: 10/28/2010
• Est. Priority Date: 04/23/2009
• Status: Active Grant

• Current Assignee: Univance Corporation
• Original Assignee: Univance Corporation
• Inventors: Masuda, Yosuke, KONDO, Hiroyuki, Yokota, Kengo, Noyori, Hedeto, Yano, Noriatsu
• Granted Patent: US 8,428,838 B2
• Time in Patent Office: Days
• US Class Current: 701/69
• CPC Class Codes: B60K 23/08 for changing number of driven wheels , for switching from driving one axle to driving two or more axles B60K17/3515 takes precedence
• CPC Class Codes: F16D 13/69 Arrangements for spreading lamellae in the released state
• CPC Class Codes: Y10T 74/20073 Control of plural mechanisms [e.g., control of transmission and control of 4 - wheel drive]

Abstract

A transmitting apparatus includes a disengaging device that disengages a driving force from a front-wheel differential device to a first driving-force transmitting direction converting unit 20 and a multi-plate clutch mechanism provided between an output of a rear-wheel differential device and a right-rear wheel and capable of successively adjusting a fastening force. Drag torque when the fastening of the multi-plate clutch mechanism is released is set smaller than friction torque of a rear-wheel drive system between the first driving-force transmitting direction converting unit and a second driving-force transmitting direction converting unit. A controller unconnects the disengaging device and releases the fastening of multi-plate clutch mechanism when switching to a two-wheel drive mode, thereby stopping the rotation of the rear-wheel drive system.

Claims

1. A driving-force transmitting apparatus for a four-wheel-drive vehicle capable of switching between a four-wheel drive mode in which distribution of a driving force to be transmitted to front wheels and rear wheels is automatically controlled according to a running condition and a two-wheel drive mode in which the driving force is transmitted only to the front wheels, the driving-force transmitting apparatus for a four-wheel-drive vehicle comprising:

a front-wheel-purpose differential device that, upon receiving a driving force from an engine, distributes the driving force to left and right front wheels;

a first driving-force transmitting direction converting unit that changes a rotating direction of the driving force from the engine for transmission to the rear wheels;

a second driving-force transmitting direction converting unit that, upon receiving the driving force from the first driving-force transmitting direction converting unit, changes a rotating direction for transmission to a rear-wheel differential device;

the rear-wheel-purpose differential device that distributes the driving force to left and right rear wheels;

a disengaging device that disengages the driving force to the first driving-force transmitting direction converting unit;

a multi-clutch mechanism provided between one of outputs of the rear-wheel differential device and one of the left and right rear wheels, the mechanism capable of successively adjusting a fastening force;

a drag-torque decreasing mechanism that sets drag torque when fastening of the multi-plate clutch mechanism is released smaller than friction torque between the first driving-force transmitting direction converting unit and the second driving-force transmitting direction converting unit; and

a controller that unconnects the disengaging device and releases the fastening of the multi-plate clutch mechanism in the two-wheel drive mode to stop rotation of the second driving-force transmitting direction converting unit from the first driving-force transmitting direction converting unit, and connects the disengaging device and adjusts the fastening force of the multi-plate clutch mechanism according to the running condition of the vehicle in the four-wheel drive mode.

2. The transmitting apparatus according to claim 1, wherein the apparatus has a structure in which the rear-wheel differential device and the multi-plate clutch mechanism are separated from each other as different rooms so that lubricating oil of the rear-wheel differential device and lubricating oil of the multi-plate clutch mechanism do not mix together.

3. The transmitting apparatus according to claim 1, wherein the drag-torque decreasing mechanism includes a lubricating-oil supply mechanism that sets a space between clutch plates wider than a predetermined value and stops or restricts supply of lubricating oil to the clutch plates in the two-wheel drive mode where the multi-plate clutch mechanism is disconnected and that supplies lubricating oil to the clutch plates in the four-wheel drive mode where the multi-plate clutch mechanism is fastened.

4. The transmitting apparatus according to claim 3, wherein the lubricating-oil supply mechanism is provided with an oil pump that rotates in reverse in the two-wheel drive mode and that is driven by an output shaft of the rear-wheel differential device that rotates forward in the four-wheel drive mode.

5. The transmitting apparatus according to claim 4, wherein the oil pump is a gear pump, and an anti-seizing processed layer is formed on a sliding contact surface with a housing of the gear pump.

6. The transmitting apparatus according to claim 4, wherein the oil pump is driven via a one-way clutch provided in a space with the output shaft of the rear-wheel differential device, and

in the two-wheel drive mode, the one-way clutch is idled to stop supply of the lubricating oil to the multi-plate clutch mechanism and, in the four-wheel drive mode, the oil pump is rotated forward to supply the lubricating oil to the multi-plate clutch mechanism.

7. The transmitting apparatus according to claim 1, wherein the lubricating-oil supply mechanism includes

an oil pump that is driven by an output shaft of the rear-wheel differential device that rotates in reverse 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 at the time of reverse rotation in the two-wheel drive mode;

a first discharge-path check valve that causes the oil discharged from the oil pump to be discharged to a region other than the multi-plate clutch mechanism at the time of reverse rotation in the two-wheel drive mode;

a second suction-path check valve that causes the oil pump to suck oil from a second suction path at the time of forward rotation in the four-wheel drive mode; and

a second discharge-path check valve that causes the oil discharged from the oil pump to be discharged to the multi-plate clutch mechanism at the time of forward rotation in the four-wheel drive mode.

8. The transmitting apparatus according to claim 1, wherein the lubricating-oil supply mechanism includes

an oil pump that is driven by an output shaft of the rear-wheel differential device that rotates in reverse in the two-wheel drive mode and rotates forward in the four-wheel drive mode;

a suction-path check valve that causes the oil pump to suck oil from a first suction path for discharge to a tank through a discharge and suction path at the time of reverse rotation in the two-wheel drive mode; and

a discharge-path check valve that causes the oil sucked into the oil pump from the dual-purpose discharge and suction path to be discharged to the multi-plate clutch mechanism at the time of forward rotation in the four-wheel drive mode.

9. The transmitting apparatus according to claim 3, wherein the lubricating-oil supply mechanism includes

an oil pump that is driven on an output side of the multi-plate clutch mechanism;

and

an opening and closing mechanism that closes a lubricating route in the two-wheel drive mode to stop supply of the lubricating oil and opens the lubricating route to supply the lubricating oil in the four-wheel drive mode.

10. The transmitting apparatus according to claim 9, wherein the opening and closing mechanism includes

a valve chamber formed in an internal axial direction of an output shaft from the rear-wheel differential device having the multi-plate clutch mechanism and supplied with the lubricating oil from the oil pump;

a valve member slidably accommodated in the valve chamber and moving in synchronization with a piston movable in an axial direction and disengaging the clutch plates of the multi-plate clutch mechanism; and

an oil supply hole for supplying the lubricating oil between the clutch plates of the multi-plate clutch mechanism, wherein

the opening and closing mechanism cuts off the lubricating oil by closing the oil supply hole with the movement of the valve member in synchronization with a movement of the piston to a clutch-unfastened position in the two-wheel drive mode, and opens the oil supply hole to supply the lubricating oil with a movement of the valve member in synchronization with a movement of the piston to a position where the clutch plates are fastened in the four-wheel drive mode.

11. The transmitting apparatus according to claim 9, wherein the opening and closing mechanism includes

an oil chamber formed in an inner axial direction of an output shaft of the rear-wheel differential device, the oil chamber to which the lubricating oil from the oil pump is supplied;

an outer-perimeter spline with a valley portion wider than a ridge portion formed on an outer perimeter of the output shaft;

an inner hub of the multi-plate clutch mechanism, the inner hub having an inner-perimeter spline formed with a valley portion wider than a ridge portion fitting in the outer-perimeter spline of the output shaft; and

a pair of oil supply holes that cuts off the lubricating oil to the multi-plate clutch mechanism at a position where the outer-perimeter spline abuts on the inner-perimeter spline with reverse rotation of the output shaft in the two-wheel drive mode and that supplies the lubricating oil to the multi-plate clutch mechanism at a position where the outer-perimeter spline abuts on the inner-perimeter spline with forward rotation of the output shaft in the four-wheel drive mode, the oil supply holes formed in the valley portions of the outer-perimeter spline and the inner-perimeter spline.

12. The transmitting apparatus according to claim 4, wherein the drag-torque decreasing mechanism includes a spring member for pressing in a direction of widening a space between the clutch plates.

13. The transmitting apparatus according to claim 4, wherein the drag-torque decreasing mechanism includes a spring member in a space formed with a piston pressing the clutch plates, the spring member for pressing in a direction of widening the space therebetween.

14. The transmitting apparatus according to claim 1, wherein the controller fastens the disengaging device after fastening the multi-plate clutch mechanism in switching from the two-wheel drive mode to the four-wheel drive mode, and unconnects the disengaging t device after releasing the multi-plate clutch mechanism when switching from the four-wheel drive mode to the two-wheel drive mode.

15. A driving-force transmitting apparatus for a four-wheel-drive vehicle capable of switching between a four-wheel drive mode in which a driving force is transmitted to front wheels and rear wheels and a two-wheel drive mode in which the driving force is transmitted only to the front wheels, the driving-force transmitting apparatus for a four-wheel-drive vehicle comprising:

a front-wheel-purpose differential device that, upon receiving a driving force from an engine, distributes the driving force to left and right front wheels;

a first driving-force transmitting direction converting unit that changes a rotating direction of the driving force from the engine for transmission to the rear wheels;

a rear-wheel-purpose differential device that distributes the driving force to left and right rear wheels;

a second driving-force transmitting direction converting unit that, upon receiving the driving force from the first driving-force transmitting direction converting unit, changes a rotating direction for transmission to a rear-wheel-purpose differential mechanism;

a first disengaging mechanism that disengages the driving force to the first driving-force transmitting direction converting unit;

a second disengaging mechanism provided at least one of a space between the rear-wheel differential mechanism and a rear-wheel left shaft and a space between the rear-wheel differential mechanism and a rear-wheel right shaft to disengage the driving force; and

a controller that unconnects the second disengaging mechanism and then releases the connection of the first disengaging mechanism when switching is made from the four-wheel drive mode to the two-wheel drive mode, and connects the second disengaging mechanism and then connects the first disengaging mechanism when switching is made from the two-wheel drive mode to the four-wheel drive mode.

16. The transmitting apparatus according to claim 15, wherein

the first disengaging mechanism is an engaging clutch mechanism that switches, with an operation of an actuator, between connection with engagement of a coupling sleeve with a clutch gear and unconnection in which the coupling sleeve is disconnected from the clutch gear,

the second disengaging mechanism is a multi-plate clutch mechanism that controls distribution of the driving force to be transmitted to the front wheels and the rear wheels by successively changing the fastening force, and

when switching is made from the four-wheel drive mode to the two-wheel drive mode, the controller releases the fastening force of the multi-plate clutch mechanism of the second disengaging mechanism for unconnection, and then sets, as for the first disengaging mechanism, the engaging clutch mechanism as unconnected with an operation of the actuator and, when switching is made from the two-wheel drive mode to the four-wheel drive mode, the controller provides a fastening force to the multi-plate clutch mechanism of the second disengaging mechanism for connection and then connects the first disengaging mechanism with an operation of the actuator.

17. The transmitting apparatus according to claim 16, wherein

the first disengaging mechanism includes

a shift rod that is moved by the actuator in a reciprocating manner in a connecting direction and unconnecting direction of the engaging clutch mechanism;

a fork provided to the shift rod to move integrally with a movement of the shift rod in a unconnecting direction and to become free with a movement of the shift rod in a connecting direction; and

a spring that always presses the fork in a connecting direction, and

when switching is made from the four-wheel drive mode to the two-wheel drive mode, with a movement of the rod in an unconnecting direction with an operation of the actuator, the shifting fork is integrally moved against the spring to detach the coupling sleeve of the engaging clutch mechanism from the clutch gear for releasing connection and, when switching is made from the two-wheel drive mode to the four-wheel drive mode, with the shifting force being set as free with a movement of the rod in a connecting direction with an operation of the actuator, the coupling sleeve of the engaging clutch mechanism is pressed onto an end face of the clutch gear by the spring for connection with engagement at the time of synchronization of rotation of both.

18. The transmitting apparatus according to claim 15, wherein an actuator that activates the first disengaging mechanism is placed on an upper portion in an orthogonal direction of the first driving-force transmitting direction converting unit placed in the vehicle.

19. The transmitting apparatus according to claim 15, wherein

the apparatus has a structure in which drag torque at the time of unconnection of the multi-plate clutch mechanism provided to the second disengaging mechanism is set smaller than friction torque from the first driving-force transmitting direction converting unit to the second driving-force transmitting direction converting unit.

20. The transmitting apparatus according to claim 19, wherein the multi-plate clutch mechanism includes a spring member for pressing in a direction of widening a space between the clutch plates.

21. The transmitting apparatus according to claim 19, wherein the multi-plate clutch mechanism includes a spring member in a space formed with a piston pressing the clutch plates, the spring member for pressing in a direction of widening a space between the clutch plates.

22. The transmitting apparatus according to claim 19, wherein the multi-plate clutch mechanism has a switching valve that operates with a movement of the piston in an axial direction, cuts off supply of oil to the clutch plates at a clutch-disconnected position where the piston is retracted, and supplies oil to the clutch plates at a clutch-fastened position where the piston advances.