Driving-force transmitting apparatus for four-wheel-drive vehicle

A driving-force transmitting apparatus for a 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 comprising:

• a front-wheel 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 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 the rear-wheel differential device;
• a first disengaging mechanism that disengages the driving force to the first driving-force transmitting direction converting unit;
• a second disengaging mechanism provided at at least one of a space between the rear-wheel differential device and a rear-wheel left shaft and a space between the rear-wheel differential device and a rear-wheel right shaft to disengage the driving force;
• and
• a controller that disconnects the second disengaging mechanism and then disconnects 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, 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 disconnection 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 a 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 disconnection, and then sets, as for the first disengaging mechanism, the engaging clutch mechanism as disconnected 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 the 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.