Device to suppress firing impulse torque induced vibrations in internal combustion engines

A device in a vehicle drive train at the output end of an internal combustion engine crankshaft to suppress firing impulse torque related vibration, said drive train including a drive sprocket freely coaxially rotatable relative to the crankshaft said drive sprocket providing input to a transmission to drive the vehicle, said device comprising:

• a first plate adapted to be coupled to the drive sprocket for coaxial rotation therewith;
• a second plate attached to the first plate for coaxial rotation therewith, at least one of said first or second plates attached to the crankshaft so that said plates and sprocket coaxially rotate with and are driven by the crankshaft;
• a first inertial ring;
• a second inertial ring, said first and second inertial rings coupled for mutual co-axial rotation, said inertial rings coaxially disposed between said first and second plates;
• friction discs disposed between the inertial rings and plates;
• and
• means for urging the inertial rings to press the discs between said rings and plates to frictionally slip couple the rings to the plates to rotate coaxially therewith below a pre-selected value of firing impulse torque, said plates frictionally slipping relative to the rings above said pre-selected value to suppress vibration related to firing impulse torques.