Actuator for friction engagement device

A friction engagement device connecting front and rear wheels of a four-wheel drive vehicle, including a clutch for controlling the distribution of engine torque to said front and rear wheels, a fixed casing enclosing said clutch, and an actuator for said clutch, said actuator comprising:

• a torque generating mechanism gear having an electric motor immovably installed on an outer portion of said casing, first and second gears coupled with an output shaft of said motor, third and fourth gears respectively engaging said first and second gears for respectively providing a first and a second pair of gears, said first and second pair of gears having slightly different gear ratios for providing different torques,
• a torque-thrust force conversion means for converting a torque difference between two elements respectively connected to said third and fourth gears to a thrust force,
• a piston means for pressing said clutch in response to said thrust force output from said torque-thrust conversion means, and
• a thrust bearing installed between said torque-thrust force conversion means and said piston means,
• wherein when said motor is activated, said clutch smoothly operates and controls said distribution of torque to said front and rear wheels.

A device for controlling torque distribution between two output shafts, which comprises:

• a first output shaft means coupled to torque generating means for outputting a first rotational movement,
• a second output shaft means for outputting second rotational movement,
• a clutch contained with a fixed casing connecting said first and second output shaft means,
• actuator means for controlling said clutch, said actuator means including:
• a gear means for providing different torques, including an electric motor immovably installed on an outer portion of said casing, first and second gears coupled with an output shaft of said motor, and third and fourth gears respectively engaging said first and second gears for respectively providing a first and a second pair of gears having slightly different gear ratios for providing said different torques,
• conversion means for converting said torque difference to a thrust force between two elements respectively connected to said third and fourth gears,
• a connection means for pressing said clutch in response to said thrust force output from said conversion means,
• wherein said actuator means controls said clutch when said motor is activated by causing said clutch to transfer torque from said first output shaft means to said second output shaft means, so that both said first and second output shaft means respectfully output said first and second rotational movement together.