Solenoid injector driver circuit
AssigneeCaterpillar Inc.
InventorsJames A. Antone, Kenneth D. Gihring, Errol W. Davis
Life of this patent
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Abstract
A solenoid driver circuit is controlled by an electronic control module ("ECM") and eliminates many components required for a high voltage power supply required by the prior art. The solenoid driver circuit includes a high voltage select switch, a select switch and a modulation switch that are controlled by the ECM. The ECM causes the switches to be opened and closed so that the back EMF created by the solenoid coil when the modulation switch is opened can be recaptured by charging a capacitor. That energy can then be used to energize the solenoid coil.
Claims11
A driver circuit, comprising:
- a solenoid coil;
- a high voltage select switch having an open and a closed position;
- a capacitor connected to said high voltage select switch and to ground;
- a modulation switch connected in series with the solenoid, said modulation switch having an open and a closed position;
- a current sensor connected to said modulation switch and to ground, said current sensor producing a current signal;
- a select switch connected to the solenoid coil, said select switch having an open and a closed position;
- a low voltage supply connected to said select switch;
- a diode connected between said modulation switch and said capacitor;
- and
- a voltage sensor associated with said capacitor, said voltage sensor producing a voltage signal responsive to a voltage level of said capacitor;
- an electronic controller connected to said voltage sensor and, said current sensor;
- wherein said electronic controller receives said voltage and said current signal, and selectively produces a first control signal associated with said select switch in response to a current command signal, wherein said first control signal causes said select switch to close;
- wherein said electronic controller selectively produces a second control signal associated with said high voltage select switch in response to said current command, voltage and current signal, wherein said second control signal causes said high voltage select switch to close;
- said electronic controller selectively produces a third control signal associated with said modulation switch in response to said current command, voltage and current signal, wherein said third control signal causes said modulation switch to close.
A method for controlling a fuel injector solenoid driver, said solenoid driver including
- connecting a high voltage capacitor to a solenoid coil in response to receiving a current command signal;
- disconnecting said capacitor from said solenoid in response to current through said solenoid exceeding a predetermined level;
- connecting a low voltage source to said solenoid in response to said current falling below a second predetermined level;
- disconnecting said low voltage source from said solenoid in response to said current through said solenoid exceeding said predetermined level;
- and
- charging said capacitor with energy created in the solenoid coil inductance as a result of both of said steps of disconnecting.
Dependencies are inferred from the claim text.