Torque transmission device for a four-wheel drive vehicle

A torque transmission device for a four-wheel drive vehicle, comprising:

• a rotary housing assembly connected to one of front and rear drive shafts which are drivingly connected respectively to front and rear axles of said vehicle;
• shaft means rotatably carried in said housing assembly and integral or rotatable bodily with the other of said front and rear drive shafts;
• a piston received within said rotary housing assembly and carried over said shaft means for movement in an axial direction of said shaft means;
• a multiple disc clutch device within said housing assembly having several outer clutch discs bodily rotatable with said rotary housing assembly and several inner clutch discs bodily rotatable with said shaft means, said outer and inner clutch discs being alternately arranged between one end of an inside wall of said rotary housing assembly and one end of said piston;
• a rotor rotatable bodily with said shaft means and received within an axially narrow circular rotor chamber which is defined by an other end surface of said piston and an other end of the inside wall of said rotary housing assembly, said rotor having several blade portions, each of said blade portions having an axial thickness substantially equal to the axial width of said rotor chamber;
• and
• high viscous fluid filled within said rotor chamber for generating a pressure acting on said piston when said rotor is rotated relative to said rotary housing due to a rotational speed difference between said front and rear drive shafts.

A torque transmission device having a rotation transmitting clutch provided between at least first and second rotational shafts for transmitting rotary motion between said at least first and second rotational shafts and a piston for operating said rotation transmitting clutch, said torque transmission device further comprising:

• a rotary housing assembly connected with said first rotational shaft for bodily rotation with said first rotational shaft and receiving said piston therein, said rotary housing assembly defining between itself and said piston a circular rotor chamber which is concentric with said first and second rotational shafts;
• a rotor received within said rotor chamber and rotatable bodily with said second shaft, said rotor having at least one fluid displacement acting portion, said at least one fluid displacement acting potion having a width substantially equal to a width of said rotor chambers between said rotary housing assembly and said piston;
• and
• high viscous fluid filled within said rotor chamber for generating within said rotor chamber a pressure acting on said piston as a result of being displaced by said at least one fluid displacement acting portion when said rotor is rotated upon occurrence of relative rotation between said first and second rotational shafts.