Electrical drive system for a sewing machine

Abstract

An improved speed controlling system for an electric motor, mainly used in a sewing machine includes a motor connected to a power supply, a speed controlling circuit or circuits for operating the motor at variably controlled speeds, and an electrical braking circuit or circuits for braking the motor upon receiving deceleration command from the speed controlling circuit(s) to transfer the motor from a high speed running state to a low speed running one. Electromechanical braking means are provided for acting on the motor, during at least a part of the braking period, the braking means being controlled by the electrical braking circuit(s). A low speed setting circuit is disposed in the speed controlling circuit(s) for maintaining the low speed running state caused by the electromechanical braking means and the electrical braking circuit(s). A stoppage commanding circuit is provided for stopping the motor operation, after the motor has been transferred to its low speed running state by a low speed setting circuit, by means of actuating again, owing to a stopping command, the electrical braking circuit(s) and/or the electromechanical braking means.

Dependencies are inferred from the claim text.