Torque transfer clutch with magnetorheological actuator and ball screw operator

A power transmission device for use in a motor vehicle having a source of drive torque and first and second drivelines, comprising:

• an input member adapted to receive drive torque from the torque source;
• a first output member adapted to transfer drive torque from said input member to the first driveline;
• a second output member adapted for connection to the second driveline;
• a torque transfer mechanism operable for transferring drive torque from said first output member to said second output member;
• said torque transfer mechanism including, a friction clutch assembly operably disposed between said first output member and said second output member, a ballscrew operator having a first screw member mounted on said second output member and a second screw member supported for axial movement relative to said first screw member for generating a clutch engagement force to be applied to said friction clutch assembly, a rotor having a first portion fixed for rotation with said first screw member and a second portion disposed in a chamber filled with a magnetorheological fluid, and a electromagnetic coil arranged to vary the viscosity of said magnetorheological fluid in response to electric control signals;
• and
• a controller for generating said electric control signals.

A motor vehicle comprising:

• a powertrain for generating drive torque;
• a first driveline including a first differential driving a pair of first wheels;
• a second driveline including a second differential driving a pair of second wheels;
• and
• a power transmission device having an input interconnecting said powertrain to said first differential, an output interconnected to said second differential, and a torque transfer mechanism operable for transferring drive torque from said input to said output, said torque transfer mechanism including a friction clutch assembly operably disposed between said input and said output, a ballscrew operator having a first screw member mounted on said output and a second screw member supported for axial movement relative to said first screw member for generating a clutch engagement force to be applied to said friction clutch assembly, a rotor having a first portion fixed to said first screw member and a second portion disposed in a chamber filled with magnetorheological fluid, an electromagnetic coil arranged to vary the viscosity of said magnetorheological fluid in response to control signals, and a controller for generating said control signals.

A transfer case for use in a motor vehicle having a powertrain and first and second drivelines, comprising:

• a first shaft driven by the powertrain and adapted for connection to the first driveline;
• a second shaft adapted for connection to the second driveline;
• a torque transfer mechanism operable for transferring drive torque from said first shaft to said second shaft, said torque transfer mechanism including an input member driven by said first shaft, an output member driving said second shaft, a friction clutch assembly operably disposed between said input member and said output member, a ballscrew operator having a first screw mounted on said output member and a second screw supported for axial movement relative to said first screw for applying a clutch engagement force on said friction clutch assembly, and a clutch actuator having a rotor fixed for rotation with said first screw with an end portion of said rotor disposed within a chamber filled with a magnetorheological fluid, and an electromagnetic coil arranged to vary the viscosity of the fluid in said chamber in response to electric control signals;
• and
• a controller for generating said electric control signals.

A transfer case for use in a motor vehicle having a powertrain and first and second drivelines, comprising:

• an input shaft driven by the powertrain;
• a first output shaft adapted for connection to the first driveline;
• a second output shaft adapted for connection to the second driveline;
• an interaxle differential operably interconnecting said input shaft to said first and second output shafts;
• a torque transfer mechanism operable for limiting speed differentiation between said first and second output shafts, said torque transfer mechanism including a first member coupled to said first output shaft, a second member coupled to second output shaft, a friction clutch assembly operably disposed between said first member and said second member, and a clutch actuator operable for applying a clutch engagement force on said friction clutch assembly;
• said clutch actuator including a ballscrew operator having a first screw mounted on said second member and a second screw supported for axial movement relative to said first screw for applying said clutch engagement force on said friction clutch assembly, a rotor fixed for rotation with said first screw and having an end portion disposed within a chamber filled with a magnetorheological fluid, and an electromagnetic coil arranged to vary the viscosity of said fluid in said chamber in response to electric control signals;
• and
• a controller for generating said electric control signals.