Four wheel drive transfer case with clutch mechanism

A transfer case for a four wheel drive vehicle, comprising:

• a planetary gear arrangement connectable to an
• output shaft of a transmission, said gear arrangement including at least three nested gear components for operably interconnecting said output shaft with both a front and a rear wheel drive output shaft such that input torque to the transfer case is normally biased to both output shafts in a predetermined ratio;
• and
• electromagnetically actuatable friction clutch means for operably and conditionably interconnecting two of said planetary gear components, said friction clutch means including the combination of a friction clutch and a ball ramp mechanism, the friction clutch having frictionally engageable interleaved elements associated at least one with each of said front and rear drive output shafts, the ball ramp mechanism having first and second relatively movable members with opposed ball ramps, with one member being operably connected to one of the drive output shafts and the other member being arranged proximate to said friction clutch and loosely mounted relative to said other member through freely turnable spherical elements positioned between said ball ramps, and electromagnetic means associated with said
• ball ramp mechanism for selectively moving the loosely mounted member toward the friction clutch to exert a compressive force against the frictionally engagable interleaved elements whereby relative rotation between the drive output shafts is controlled by a torque level established by the compressive force exerted on the friction clutch.

An automotive transfer case having one rotary input shaft and two rotary output shafts, said transfer case comprising:

• a housing;
• a planetary gear set having at least three elements arranged within said housing, said three elements including a sun gear element connectable with one of said shafts, a ring gear element connectable with a second of said shafts, and a pinion gear element assembly intermeshing with both the sun and ring gear elements and which is operably connectable with the third shaft such that input torque to the transfer case is normally biased to both output shafts in a predetermined ratio;
• and
• electronically responsive biasing clutch means operative to selectively interconnect two of the planetary gear elements in a manner whereby biasing torque between the other two shafts through said clutch means and wherein said biasing clutch means comprises an electromagnetic clutch having a stationary magnetic coil disposed within said housing with the operative effect of said clutch means being modulatable as a function of the energized state of said magnetic coil.

An automotive transfer case having one rotary input shaft and two rotary output shafts, said transfer case comprising:

• a housing;
• a planetary gear set having at least three elements arranged within said housing said three elements including a sun gear element connectable with one of said output shafts, a ring gear element connectable with said input shaft, and a pinion gear element assembly intermeshing with both the sun and ring gear elements and which is operably connectable with the other output shaft such that input torque to the transfer case is normally biased to both output shafts in a predetermined ratio;
• and
• electronically responsive biasing clutch means operative to selectively interconnect two of the planetary gear elements in a manner whereby biasing torque between the two output shafts through said clutch means and wherein the biasing clutch means is comprised of a friction clutch having interleaved friction plates wherein one or more of said friction plates rotate with one rotary output shaft and the remaining friction plates rotate with the other output shaft, a ball ramp mechanism including first and second relatively movable members with opposed ball ramps, with one of the members being operably connected to one of said rotary output shafts and the other member being loosely mounted relative to said one member through ball members located between said ball ramps, and a third member operably connected to said other output shaft, electromagnetic means associated with said ball ramp mechanism for coupling the loosely mounted member to said third members as an operable assembly and moving said operable assembly toward said friction clutch to exert a compressive force thereon whereby relative rotation between the output shafts is restricted by a torque level established by the compressive force exerted on the clutch.

Apparatus for use on a vehicle said apparatus including an input shaft and first and second output shafts, said apparatus being operable to continuously provide driving torque to all four wheels of said vehicle, said apparatus comprising:

• a housing;
• first operative means disposed in said housing for transfering input torque to said apparatus to both of said output shafts in a manner such that rotation of said input shaft normally drives the other shafts in a predetermined ratio and wherein said first operative means comprises three nested relatively rotatable elements including a sun gear operably connected to one of said output shafts, a ring gear operably driven by the input shaft, and intermeshing pinion gears operably connected to the other of said output shafts;
• and
• modulatable biasing clutch means defining a second operative means operably interposed between any two of said relatively rotatable elements of said first operative means for transferring torque and controlling relative rotation between said output shafts by a torque level established through energization of said clutch.

Apparatus for use on a vehicle, said apparatus including an input shaft and first and second output shafts, said apparatus being operable to provide driving torque to all four wheels of said vehicle, said apparatus comprising:

• a housing;
• operative means disposed in said housing for transferring input torque to both of said shafts in a manner such that rotation of said input shaft normally drives the other shafts in a predetermined ratio and wherein said operative means comprises three nested relatively rotatable elements including a sun gear operably connectable to one of said output shafts, a ring gear operably driven by the main drive shaft, and intermeshing pinion gears operably connectable to the other of said output shafts;
• and
• modulatable biasing clutch means operably interposed between any two of said relatively rotatable elements of said operative means for transferring torque and controlling relative rotation between said output shafts by a torque level established through energization of said clutch, said biasing clutch means comprises the combination of a friction clutch, a ball ramp mechanism, and electromagnetic means associated with said ball ramp mechanism for selectively energizing said friction clutch.

A transfer case for a full-time four wheel drive vehicle which is driven by a power source comprising:

• a housing;
• a planetary gear assembly mounted in said housing for normally transfering torque derived from said power source to each of said four wheels, said planetary gear assembly including an externally toothed sun gear rotatable about an axis of rotation thereof and operably connected to a first output drive shaft, an internally toothed ring gear rotatable about an axis of rotation substantially coaxial with the axis of rotation of said sun gear and operably connected to an input drive shaft, and a plurality of planet pinions carried by a pinion carrier which turns about the axis of rotation of the sun gear with which is operably connected to a second output drive shaft, said planet pinions meshing with the sun gear and ring gear such that rotation of any one shaft effects rotation of the others;
• and
• frictional coupling means having first and second friction element means respectively mounted for rotation with said first and second rotary output shaft and electromagnetically actuated means for modulating the frictional engagement between said first and second friction discs in a manner controlling the transfer of torque and the relative rotational speed between said first and second rotary power output shafts.