Patent ID: 6050281
Filing Date: 2000-04-18
Classification: F23N,Y10T

Abstract:
In gas valve apparatus of the type having first and second valves arranged in series and operated by first and second electrically energizable actuator coils respectively, the first and second actuator coils requiring greater current for actuation from an unactuated state than for maintenance in an actuated state, one of said first and second actuator coils requiring a greater current for actuation then the other coil, the improvement which comprises:first and second conductors for supplying electric current at a substantially unipolar voltage between said conductors, the unipolar voltage, when uninterrupted for at least a predetermined time interval, being sufficient to produce electric current through the first actuator coil adequate to actuate the first valve;first and second interconnection nodes;a unidirectional current element connecting said first and second interconnection nodes, and operable to permit current flow toward said second interconnection node;first connecting means connecting the first actuator coil between said second conductor and said first interconnection node;second connecting means connecting the second actuator coil between said second interconnection node and said first conductor;an energy storage device connected between said second interconnection node and said first conductor; andelectrically controllable switch means connected between said first conductor and said first interconnection node, adapted to receive a control signal which causes said electrically controllable switch means to allow current to flow through the first actuator coil during a first predetermined time interval adequate to actuate the first valve from an unactuated state, and causes said electrically controllable switch means to chop the current flowing through the first actuator coil at a duty cycle adequate to maintain the first valve in an actuated state but inadequate to actuate the first valve from an unactuated state, during a second time interval.