The present invention relates to a control circuit for controlling at least one solenoid valve for fuel metering in an internal combustion engine.
Such a control circuit is for example discussed in German Published Patent Application No. 195 39 071. Using this control circuit, rapid solenoid valves are controlled, e.g., for common rail fuel injection or gasoline direct injection of internal combustion engines, via booster and battery supply voltage FET switches, and the energy is released during the transition from the pickup current to the retaining current being stored in a capacitor.
This circuit system may require a multiplicity of components and complex driver circuits that make it possible to use large currents to drive the valves to be controlled. Here, the resulting dependencies of the cutoff edges during the rapid disconnection of the solenoid valves from the battery voltage may be disadvantageous.
An object of an exemplary embodiment of the invention is to provide a control circuit for controlling at least one solenoid valve for fuel metering in an internal combustion engine, so that the cutoff edges during the rapid disconnection are largely independent of modifications of the battery voltage.
The control circuit according to an exemplary embodiment of the present invention includes a recharge circuit that is connected with the first and second terminal of the supply voltage to produce a pre-stabilized recharge voltage for the storage capacitor from the battery supply voltage, and is connected with the first switching apparatus, arrangement or structure, the recharge circuit supplying, via third switching apparatus, arrangement or structure, situated between the first terminal of the at least one solenoid valve and the recharge circuit, the solenoid valves with current from the energy stored in the storage capacitor in the booster phase, the recharge circuit also containing the storage capacitor as well as a fourth switching apparatus, arrangement or structure, that, controlled by the control apparatus, arrangement or structure, activates the recharge circuit in order to recharge the storage capacitor.
The dependence of the solenoid valve shutoff on modifications in the battery voltage is omitted to the greatest possible extent. The usable range of operation is thus expanded.
It is believed that the battery voltage can include a large range without influencing the shutoff (or operating, clearing) time of the solenoid valves. Here, the stabilized voltage can lie above or below the battery voltage.