Abstract: An injector for a fuel injection system comprising: input means for receiving drive signals from an injector drive circuit for controlling operation of the injector, and an ID chip wherein the injector further comprises an electronic latch means arranged to move between a first state in which the electronic latch means is arranged to be enabled such that the ID chip is in communication with the injector drive circuit via the input means, and a second state in which the electronic latch means is arranged to be disabled such that the ID chip is not in communication with the injector drive circuit via the input means wherein the electronic latch means is arranged to move from the first state to the second state upon receipt at the injector of a drive pulse signal from the injector drive circuit.

Abstract: An injector for a fuel injection system comprising: input means for receiving drive signals from an injector drive circuit for controlling operation of the injector, and an ID chip wherein the injector further comprises an electronic latch means arranged to move between a first state in which the electronic latch means is arranged to be enabled such that the ID chip is in communication with the injector drive circuit via the input means, and a second state in which the electronic latch means is arranged to be disabled such that the ID chip is not in communication with the injector drive circuit via the input means wherein the electronic latch means is arranged to move from the first state to the second state upon receipt at the injector of a drive pulse signal from the injector drive circuit.

Abstract: A drive circuit for controlling at least one device having first and second electromagnetically operable actuators, the drive circuit having first and second terminals for connection to a voltage supply and comprising a first controllable switch in connection with one side of the actuators and the first terminal. Each actuator has an associated second controllable switch in connection with the other side of the respective actuator, whereby opening and closing of the first and second switches serves to control selection and actuation of the actuators. The circuit further comprises a sensor arrangement for providing independent sensing of the current flowing through each of the actuators, each actuator having an associated diode in connection with the respective second controllable switch to ensure current flows through the sensor arrangement when the first controllable switch is opened and the second controllable switch is closed.

Abstract: A control circuit for an electromagnetically operable fuel control valve of a vehicle engine includes a tank capacitor which upon closure of first and second controllable switches supplies current to the winding of the valve to achieve a high rate of rise of current in the winding and rapid operation of the valve. Following operation of the valve it is maintained in its operated state by current chopping action, the current rise being achieved by drawing current from a low voltage source through a third controllable switch. The current fall is at a high rate and the resultant high voltage induced in the winding is utilized to recharge the tank capacitor.

Abstract: A method of operating a drive circuit of a solenoid of an electromagnetic device including an armature, the drive circuit including switch means in series with the solenoid, comprising closing the switch means to achieve a high rate of current increase in the solenoid, opening the switch means when the current reaches a predetermined level and allowing the current to decay, the movement of the armature from a first to a second position being completed whilst the current is decaying and monitoring the decaying current using a sensing circuit which includes means responsive to a discontinuity in the decaying current flow when the armature reaches the second position.

Abstract: A method of detecting when a moving component of an electromagnetically operable device attains a final position after de-energizing a winding of the device comprises allowing the energizing current to fall to zero and prior to the component reaching its final position, connecting a sensing circuit in parallel with the winding, the current flow in the sensing circuit increasing from the instant of connections and decreasing when the component reaches its final position, said sensing circuit detecting the change in current flow.