Load limiting mechanical coupling for electrical rotor - uses bolts designed to fracture at specified torque leaving only elastic coupling

摘要

The application is principally to variable speed ac motors where the applied variable frequency may, in certain circumstances, set up undesirably high oscillatory torques in the shaft system. To protect the mechanical parts against the high stresses which could result the solid coupling between the rotor hub (1) and the shaft (2) is made by means of special bolts (13) designed to fracture at a predetermined torque in excess of the full load value. When the bolts fracture the coupling is maintained by an elastic drive employing bushes (3) of an elastomeric material. The resulting change of natural frequency helps to damp out the oscillations with minimal damage to the rotor. The fit between hub and shaft is typically very light.