Abstract: A fuel injection system for a compression ignition engine includes pulse length control means which determines the instant and duration of opening of a series of injector valves in accordance with the output of a digital memory unit, empirically programmed to match the specific engine. The memory is addressed by two inputs, one derived from an engine speed transducer and the other derived by combining analogue signals from the speed transducer and from a demand transducer. The system operates without any feedback representing the quantity of fuel injected so that no fuel flow transducers are required.

Abstract: An engine exhaust recirculating valve is operated by a solenoid. The valve is normally open, but has an electronic control circuit, including an engine speed transducer, which energizes the solenoid to close the valve when the engine speed is above a predetermined level.

Abstract: A fuel supply system for an internal combustion engine includes a pump having a control member movable by an actuator. The actuator is powered by an amplifier which receives a control signal from an operational amplifier. One input of the opertional amplifier is connected to a summing junction to which signals representing speed demand, actual speed and control rod position are supplied by three transducers. The signal from the transducer which indicates the control rod position passes by way a circuit means which ensures that a derivative of the signal is applied to the summing junction.

Abstract: A Fuel System for an engine includes an actuator for controlling the output of a pump and a pair of d.c. supply lines the voltage across which is determined by a voltage regulator. A series circuit including a resistor, a relay coil and a transistor is connected across the supply lines and first means is provided for turning transistor off if the current flow through the actuator exceeds a predetermined value. Second means including a resistor is provided to maintain transistor de-energised when it has been turned off to prevent further operation of the actuator. In addition switch means is provided to short circuit the resistor if the potential between the supply lines falls below a second predetermined value.

Abstract: A fuel system for an engine has a first summing amplifier to which are fed signals representing demanded and actual values of the output of a pump supplying fuel to the engine, together with a signal representing engine speed. The summing amplifier compares the signals it receives and produces an output controlling the output of the pump, and there is also a second summing amplifier to which are fed electrical signals representing engine speed and a reference, a discriminator coupling the two summing amplifiers to a means for controlling the pump, so that the output from the discriminator at any instant is the output from the amplifier demanding the least fuel.

Abstract: A fuel system for an engine has a pump which supplies fuel to the engine and an actuator for controlling the pump output. The actuator is controlled by a control circuit to which are fed electrical signals representing demanded engine speed, actual engine speed and pump output. The control circuit sets the slope of the pump output versus speed curves of the engine, and speed-sensitive means operates below a predetermined engine speed for modifying this slope to make it shallower and so produce a smaller change in pump output for a given change in speed.

Abstract: An electronic governor, particularly for a diesel engine has a summing amplifier receiving signals representing the output of the pumps supplying fuel to the engine, engine speed, and engine demand. The summing amplifier serves to produce an output for operating the pump in accordance with predetermined engine current characteristics. A second summing amplifier may be used to override the first summing amplifier to limit maximum fuel. Alternatively, the first summing amplifier may compare demanded fuel supply with actual fuel supply, in which case the second amplifier sets the maximum speed.

Abstract: A fuel system for an engine, particularly a compression-ignition engine, has a pump supplying fuel to the engine and a control member for determining the output of the pump, the control member being itself controlled by a control circuit receiving parameters one of which is measured by transducer means. The transducer means is designed so that if it fails, the fuel system fails safe. In another arrangement, in which failure of the transducer means results in an output which would increase fuel, then the failure is detected and action is taken.

Abstract: An engine fuel system, particularly for a compression ignition engine, has a control arrangement for determining the quantity of fuel injected in accordance with the position of a control member such as an accelerator pedal. For part of its movement, the pedal produces an output which is a certain function of the pedal position, and for another part of the movement, an output is produced which is a different function of the pedal position.