The present device provides a fuel injector including a two-input, self-triggering monostable driver circuit for an electromechanical valve is disclosed. Upon receipt of an initiation signal, the driver circuit generates a predetermined current profile in a coil. A current sensing mechanism senses the current flowing through the coil, enabling a current threshold generator to detect a preset peak current threshold state. Upon detection of the preset peak current threshold state, the current threshold generator establishes a new hold current threshold state in the coil. A rapid decay generator forces a rapid transition from peak current to hold current within the coil. The hold current is maintained within preset hysteretic limits until the valve cycle is terminated by removing the initiation signal from the inputs.
This application claims the benefit of U.S. Provisional Application No. 60/105,242 filed Oct. 22, 1998, which is hereby incorporated by reference in its entirety.
A diagnostic tool (10) for testing fuel injectors (50) and their driver circuits (IDM), including associated wiring harnesses, in a fuel injection system of an engine in a motor vehicle. The tool has a driver-connection port (16) for connection to the driver circuits and an injector-connection port (18) for connection to the fuel injectors via jumper wiring harnesses. The tool can perform 1) a fuel injector test, by connecting an ohmmeter to the tool to measure injector coil resistance, 2) a driver-injector test, by connecting an oscilloscope to the tool to observe traces of electric current waveforms applied to the fuel injector, 3) a driver circuit test, by connecting the respective driver circuit to a load that simulates the load imposed by the respective fuel injector, and 4) a cylinder contribution test, by selectively disconnecting certain fuel injector actuators from their driver circuits while leaving the remaining fuel injector actuators connected to their driver circuits.
A control circuit for controlling solenoid valves for fuel metering in an internal combustion engine (banks I and II) includes a recharge circuit having a throttle coil in series with a diode and with a storage capacitor, as well as an FET power transistor connected in parallel with the series circuit of the diode and the storage capacitor. The solenoid valves of the individual banks are switched off during the rapid extinguishing with a voltage produced by the recharge circuit. To minimize the influence of the supply voltage, which comprises a wide range, the HS-FET is switched off during the rapid extinguishing phases.
A method for controlling a fuel injector provided with an electrically operated electomagnetic actuator in such a manner as to open the injector for a determined injection time; the method providing that the injector be operated with a first current waveform if the injection time is greater than a predetermined threshold value, and that the injector be operated with a second current waveform if the injection time is less than the predetermined threshold value; both the current waveforms have an identical initial portion, during which the current passing through the injector is caused to rise until it reaches a peak value, which is maintained by cyclic switching of the voltage applied to the injector between two different values.
