Abstract: An actuator for the throttle of an internal combustion engine comprises a torque motor and a return spring. The spring provides a monotonically increasing return force for increasing throttle opening. The motor has a torque characteristic such that, for constant motor current, the torque decreases monotonically for increasing throttle opening. The actuator thus has a single-valued function of throttle position versus motor current and allows open loop control as well as stable closed loop control.

Abstract: An electromagnetically-operable fuel injector comprising a fuel chamber having an outlet nozzle and into which a solenoid core projects. A ball valve in the gap between the core and the nozzle orifice and movable towards and away from the core to seat and unseat a valve seat around the nozzle orifice by energization of an electromagnetic circuit. Compensating structure is provided which respond to changes in temperature by changing a physical characteristic. The compensating structure function either to change the length of the core or to adjust the position of the valve seat relative to the core such that any tendency for fuel metering characteristics of the injector to be changed by a change in temperature in the injector is countered whereby operation of the injector to inject fuel is substantially independent of temperature change.

Abstract: A motor vehicle fuel system operable selectively to supply metered quantities of petrol or LPG in its gaseous state to a carburetter induction passage. The LPG system includes a pair of digital injection valves in a body having a common inlet, a common outlet and an outlet chamber into which the gaseous LPG is injected alternately by the two valves. The metered pulsed outputs of the two valves collected in the outlet chamber is conveyed as a single gaseous fuel supply to the carburetter induction passage. The injection valves can be located spaced from the carburetter whereby to avoid excessive heating. An electronic control unit including a microprocessor and a data store matrix responds to certain engine operating conditions, including engine speed and engine loading, and controls alternate operation of the valves in synchronism with the engine ignition firing sequence. Under certain conditions one of the valves may open before the other closes.

Abstract: A motor vehicle fuel system operable selectively to supply metered quantities of petrol or LPG in its gaseous state to a carburetter induction passage. The LPG system includes a single stage pressure regulator and an injection valve which may be a digital or an analogue valve. The regulator operates to vary the pressure of gaseous LPG with variations in engine loading by referring that pressure across a single diaphragm to the pressure established in the induction passage downstream of the throttle valve by operation of the engine, while maintaining that regulated gas pressure above that subsisting in the induction passage upstream of the throttle valve.

Abstract: An air/fuel induction system includes a pair of solenoid valves injecting fuel into an induction passage of a multi-cylinder engine. The valves supply fuel upstream of the inlet manifold to the engine and do not therefore direct fuel to specific cylinders. The solenoids (36, 36a) operate alternatively through pulses developed by drive units controlled by a microprocessor-based control unit (19). Each valve is independently timed by a respective timer-counter (44, 45) and valve operation overlaps in some circumstances. This allows smaller valves to be used and overcomes the problem of gusting at low speeds. The system may be applied to an LPG fuel system used as an additional fuel supply.

Abstract: A single-point fuel injection system including an electromagnetically-operable ball valve injector. The injector comprises a hollow body which is surrounded by an annular gallery through which fuel is circulated under pressure continuously. Inlet ports are formed in the body whereby fuel from the gallery enters a chamber within the body in a direction transverse to the axis of the injector. The chamber communicates with the nozzle orifice via an aperture within which the ball valve is located. The difference between the diameter of the aperture and the diameter of the ball is sufficiently small to restrict fuel flow from the chamber to the nozzle orifice so that the valve is urged to seat and close the nozzle orifice by the differential fluid pressure loading on it.

Abstract: A single point fuel injection air/fuel metering device comprises a tubular housing with a flap pivotally mounted therein upstream of a throttle valve. The flap is dynamically balanced about its pivot axis, which is offset from the axis of the tubular housing and is wholly within the bore of the tubular housing throughout its range of angular movement. A flap return spring which is anchored in the tubular housing upstream of the flap acts at the center of area of the flap. A rotary damper spindle and a rotary potentiometer spindle project coaxially into the housing bore from opposite sides thereof and the flap is clamped to them so that it is supported by the low friction bearings of the damper and the potentiometer. An injector is mounted to inject fuel into the bore between the flap and the throttle valve.

Abstract: A motor vehicle fuel system operable selectively to supply metered quantities of petrol or LPG in its gaseous state to a carburetter induction passage. The LPG system includes a single stage pressure regulator and an injection valve which may be a digital or an analogue valve. The regulator operates to vary the pressure of gaseous LPG with variations in engine loading by referring that pressure across a single diaphragm to the pressure established in the induction passage downstream of the throttle valve by operation of the engine, while maintaining that regulated gas pressure above that subsisting in the induction passage upstream of the throttle valve.