Torsion damping mechanism for a supercharger

A rotary blower of the backflow-type comprising a housing;

• first and second meshed lobed rotors rotatably disposed in the housing for transferring relatively low pressure inlet port air to outlet port air controllable between relatively low and high pressures;
• first and second meshed timing gears respectively fixed to the first and second rotors for preventing contact of the meshed lobes;
• first drive means adapted to be rotatably driven by a positive torque about an axis in one drive direction at speeds proportional to speeds of a periodic combustion, torque transmitting engine selectively controllable between idle and maximum speeds;
• a second drive means fixed to one of the timing gears;
• a torsion damping mechanism rotatably disposed between the driver and characterized by:
• annular means disposed for rotation about an axis and fixed to one of the drive means, the annular means including an annular member formed of elastomeric material having a hardness in the range of 50-80 shore D durometer and an outer shell banded about the annular member and formed of rigid material relative to the annular member, the annular member including a plurality of circumferentially spaced apart and generally arcuate-shaped slots each having first and second ends respectively defining stops in the one direction and in the opposite direction of rotation;
• axially extending pins each having one end loosely received by one of the slots and the other end fixed to the other drive means;
• and
• spring means for flexibly transmitting positive torque between the drive means and operative in a static state of the mechanism to position the pins closer to the second stop than the first stop.