Abstract A solid state electrical switching circuit of high efficiency is employed to increase the speed with which an electromagnet operated device, such as a relay or a hydraulic valve, can be actuated without increasing the power required to maintain the device in the actuated state. The circuit can also be made to provide the momentary increased electrical current required to obtain a given mechanical force when the magnetic gap between the solenoid core and the movable pole piece is open. Both actuation and de-actuation speed of the electromagnet are increased and rapid deactuation is achieved either by a high reverse voltage applied to the solenoid and the return of its energy to the power source or by a diode and capacitor network which transfers the magnetic energy to a second solenoid which thereupon becomes energized.
In combination with an electromagnetically operated device, a circuit for producing rapid current growth in the coil of said device, and for maintaining a predetermined level of current in said coil, an electrical circuit comprising: a source of relatively high voltage capable of effecting rapid current growth in said coil; semiconductor switching means responsive to external control for applying said high voltage source to energize said coil, said semiconductor switching means operating in a switching mode as a substantially non-dissipative element; first means for sensing the current in said coil to open said semiconductor switching means when a predetermined coil current value is reached, and for closing said switch intermittently thereafter, to maintain said predetermined coil current value; and second means subject to external control for applying said high voltage source to said coil in opposite polarity, thereby accelerating the rate of current decline in said coil.
Claim 2
Dependent Claim
147 words
In combination with an electromagnetically operated device, a circuit for producing rapid current growth in the coil of said device, and for maintaining a predetermined level of current in said coil, an electrical circuit comprising: a source of relatively high voltage capable of effecting rapid current growth in said coil; semiconductor switching means responsive to external control for applying said high voltage source to energize said coil, said semiconductor switching means operating in a switching mode as a substantially non-dissipative element; first means for sensing the current in said coil to open said semiconductor switching means when a predetermined coil current value is reached, and for closing said switch intermittently thereafter, to maintain said predetermined coil current value; and second means subject to external control for applying said high voltage source to said coil in opposite polarity, thereby accelerating the rate of current decline in said coil.
Claim 3
Dependent Claim
62 words
Apparatus according to claim 1 in which a shunt diode path is provided to permit continued current flow through said coil, said diode being poled so as not to conduct in response to forward energization from said source, but to conduct in response to the reverse coil voltage extant between applications of said source intermittently to said coil by saiD first means.