Electric driving device with controlled speed

Claim 1

A CONTROL CIRCUIT FOR A COMMUTATOR MOTOR HAVING AN ARMATURE WINDING AND A FIELD WINDING CONNECTED IN SERIES COMPRISING, A CONTROLLED RECTIFIER HAVING FIRST AND SECOND ELECTRODES WHICH DEFINE CURRENT PATH THEREIN AND A CONTROL ELECTRODE FOR INITIATING CURRENT FLOW IN SAID PATH, A PAIR OF INPUT TERMINALS ARRANGED TO BE CONNECTED TO A SOURCE OF ALTERNATING CURRENT, MEANS CONNECTING SAID MOTOR IN A FIRST SERIES CIRCUIT WITH SAID FIRST AND SECOND ELECTRODES OF SAID CONTROLLED RECTIFIER ACROSS SAID INPUT TERMINALS, THE FIRST ELECTRODE BEING DIRECTLY CONNECTED TO ONE OF SAID INPUT TERMINALS, A FIRST RESISTOR AND A CAPACITOR CONNECTED IN A SECOND SERIES CIRCUIT ACROSS SAID INPUT TERMINALS AND IN PARALLEL WITH SAID FIRST SERIES CIRCUIT SO THAT SAID CAPACITOR IS CHARGED TO A GIVEN VOLTAGE LEVEL DURING A PORTION OF THE PERIOD SAID CONTROLLED RECTIFIER IS NONCONDUCTIVE, MEANS INCLUDING A DEVICE HAVING A GIVEN THRESHOLD VOLTAGE COUPLED TO SAID CONTROL ELECTRODE AND RESPONSIVE JOINTLY TO THE VOLTAGE ACROSS SAID CAPACITOR AND THE INDUCED VOLTAGE IN THE MOTOR ARMATURE FOR CONTROLLING THE IGNITION POINT OF SAID CONTROLLED RECTIFIER IN ACCORDANCE THEREWITH, AND CIRCUIT MEANS SHUNTING SAID FIELD WINDING SO AS TO PROVIDE A CIRCULATING CURRENT PATH FOR THE ENERGY OF SAID FIELD WINDING DURING SAID NON-CONDUCTIVE PERIODS OF THE CONTROLLED RECTIFIER.