Electromagnetic operating device

An electromagnetic operating device constituting an electromechanical transducer for exerting a mechanical output on a valve element against a spring force preloaded on the valve element, comprising:

• a solenoid coil including a plurality of split coils which are electrically independent from each other;
• a magnetic core structure including a fixed core, a movable core and a yoke, said core structure being assembled with said solenoid coil in such a way as to form a magnetic path loop through which magnetic fluxes produced from the split coils pass in common;
• an excitation controller for selectively switching and controlling the excitation to each of the split coils;
• and
• a transmission mechanism for transmitting to the valve element the mechanical output on the basis of the displacement of the movable core magnetically attracted to the fixed core when any one or more of the split coils are excited,
• wherein the excitation controller includes a plurality of semiconductor switching devices for individually switching excitation currents of said split coils, a pulse width modulator for periodically switching-driving the semiconductor switching devices under sequential pulse commutation control with phase differences corresponding to the number of the split coils in accordance with a sync signal, and a current amplifier for producing an excitation current of magnitude corresponding to a current command value externally supplied, and wherein each output pulse width of the pulse width modulator is varied in accordance with the command value by the output of the current amplifier thereby changing an operation time width of each of the semiconductor switching devices in accordance with the output pulse width.

An electromagnetic device constituting an electromechanical transducer for exerting a mechanical output on a valve element against a spring force preloaded on the valve element, comprising:

• a solenoid coil including a plurality of split coils which are electrically independent from each other;
• a magnetic core structure including a fixed core, a movable core and a yoke, said core structure being assembled with said solenoid coil in such a way as to form a magnetic path loop through which magnetic fluxes produced from the split coils pass in common;
• an excitation controller for selectively switching and controlling the excitation to each of the split coils;
• and
• a transmission mechanism for transmitting to the valve element the mechanical output on the basis of the displacement of the movable core magnetically attracted to the fixed core when any one or more of the split coils are excited,
• wherein the split coils include a first split coil and a second split coil, the coil time constant of the second split coil being smaller than that of the first split coil, and
• wherein the excitation controller comprises a current switching circuit for exciting the second split coil with a first current value over the limited period at the excitation start initial stage, thereafter substantially shutting off excitation of the second split coil and starting excitation to the first split coil with a second current value lower than the first current value.