Transfer case with multi-gear transfer mechanism

#The present invention relates to transfer cases and more particularly to a transfer case having a multi-gear transfer mechanism.

#Traditionally, four-wheel drive (4WD) and all-wheel drive (AWD) vehicles enable transfer of drive torque, produced by an engine and supplied through a gear reducing transmission, to front and rear wheel assemblies. Depending upon the particular vehicle configuration, drive torque can be transferred to both the front and rear wheel assemblies on a full-time basis, part-time basis or “on-demand” basis. A vehicle using an “on-demand” system, normally operates in two-wheel drive (2WD) driving one of the front and rear wheel assemblies and selectively transfers drive torque to the other of the front and rear wheel assemblies in response to vehicle driving conditions.

#A transfer case is generally provided for enabling the split of drive torque between the front and rear wheel assemblies. The transfer case includes an input, operably interconnected to an output of the transmission, a first output shaft and a second output shaft, respectively interconnected with the wheel assemblies. A transfer mechanism is provided therein for selectively engaging the first and second output shafts, enabling the transfer of drive torque therebetween. The transfer case must be conveniently packaged within a vehicle underbody, avoiding interference with other vehicle components including drive shafts, exhaust, suspension, vehicle frame and the like. Packaging of the transfer case within a vehicle underbody has become more difficult in recent years, as automakers seek to implement 4WD/AWD systems in smaller vehicle applications.

#The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

#FIG. 1 is a schematic view of a vehicle driveline implementing a transfer case in accordance with the principles of the present invention;

#FIG. 2 is a cross-sectional view of a first preferred embodiment of the transfer case of FIG. 1;

#The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

#With reference to FIG. 1, an exemplary vehicle driveline 10 is shown including an engine 12, a transmission 14, a transfer case 16, a rear drive shaft 18, a rear wheel assembly 20, a front drive shaft 22 and a front wheel assembly 24. The engine 12 is operably interconnected with the transmission 14, which is operably interconnected to the transfer case 16. The engine 12 produces drive torque that is transferred to the transfer case 16 through selective gear ratios of the transmission 14. The transmission 14 is one of an automatic or manual type, as is known in the art. The transfer case 16 selectively splits the drive torque from the engine 12 for driving the front and rear wheel assemblies 24, 22.

#A controller 30 is provided and is in communication with a hydraulic source 32 and a sensor group 34. The sensor group 34 detects current driving conditions and relays that information to the controller 30. The controller 30 determines what action is required, in response to the driving conditions, and selectively engages the hydraulic source 32 for appropriate manipulation of the transfer case 16. Control of the transfer case 16 is described in further detail hereinbelow.