Patent ID: 7832378
Filing Date: 2010-11-16
Classification: F02D

Abstract:
1. A device for switching a inductive fuel injection valves, wherein, in the case of a bistable fuel injection valve having an opening and closing coil, the magnetic holding forces induced by remanence which hold a valve needle firmly in a closed position are eliminated by way of a negative current generated in the closing coil in order to accelerate the opening of the valve, and which hold the valve needle firmly in the open position are eliminated by way of a negative current generated in the opening coil in order to accelerate the closing of the valve; and wherein, in the case of a standard fuel injection valve having an opening coil and a closing spring, eddy currents in the magnetic material of the opening coil that are induced after the actuation signal has been turned off and decay only slowly are eliminated by way of a negative current generated in the opening coil; wherein a current through the opening or closing coil in the opposite direction to the direction of the actuation current is defined as the negative current; the device comprising: a circuit configuration with a coil of a fuel injection valve, said coil being controlled by a switching signal via a pulse width modulation unit; said coil having a first terminal connected to a positive pole of a supply voltage source by way of a first switching transistor and a second terminal connected to reference potential by way of a second switching transistor; said first switching transistor having a source terminal connected to said first terminal of said coil, a drain terminal connected to the positive pole of the supply voltage source, and a gate terminal connected to an output of said pulse width modulation unit; said second switching transistor having a source terminal connected to reference potential and a drain terminal connected to said second terminal of said coil; a freewheeling diode connected to conduct current from the reference potential to one terminal of said coil and a recuperation diode connected to conduct current from the other terminal of said coil to the positive pole of the supply voltage source; a third transistor connected in parallel with said freewheeling diode, said third transistor having a source terminal connected to reference potential and a drain terminal connected to a connection node between said freewheeling diode and one terminal of the coil; a complementary Darlington current mirror connected to the positive pole of the supply voltage source via a first resistor; said current mirror including a fourth transistor with a source terminal connected to said second terminal of said coil, and a sixth transistor with a source terminal connected to reference potential via a series circuit formed of a seventh transistor and a fifth resistor; said third transistor and said seventh transistor having gate terminals connected to one another and connected such that a negative current control signal may be supplied thereto; a capacitor connected in parallel with said a series circuit formed of said sixth transistor, said seventh transistor, and said fifth resistor; and a further series circuit connected in parallel with said capacitor, said further series circuit including a vehicle onboard voltage source connected to reference potential on one side and a protection diode conducting current toward said capacitor.