Abstract: A fuel control device or fuel valve assembly includes a valve for metering flow of gaseous fuel to an engine, a drive device associated with the valve to adjust the effective flow area of the valve, a flow meter with at least one fixed area orifice located upstream of the valve, and one or more sensors to measure predetermined parameters of the fuel flowing through the flow meter. A controller receives input from the flow sensor or sensors and a fuel demand signal from the engine control, calculates current flow rate based on the sensor inputs, and controls the drive device to adjust the valve flow area up or down depending on the difference between the calculated flow rate and current fuel demand signal.

Abstract: A gas substitution ratio control system varies natural gas flow to a bi-fuel engine based on detected diesel flow to maintain a desired gas substitution ratio (GSR), without any requirement to sense engine load. In other words, GSR is controlled without monitoring engine load level. In one system, an engine is first calibrated to map actual gas and diesel flows to provide the correct GSR for all engine loads. The calibration data is then stored and diesel flow rate is monitored. The current detected diesel flow rate is used to determine the required gas flow rate for correct GSR. Gas flow to the engine is then adjusted to correspond to the required gas flow rate. Other embodiments meter gas to maintain the diesel flow rate at the same minimum level for all loads, or meter gas and diesel fuel flows to match a map of the limiting fuel energy based GSR (gas fuel energy rate/total fuel energy rate) at all loads for each engine model.

Abstract: A gaseous carburetor or fuel control system includes a fuel metering assembly, a venturi mixer assembly, a throttle assembly, and an electronic control unit. The control unit controls the fuel metering assembly in a closed loop manner based on detected gas and air pressure to an air/fuel mixing venturi. An electronic governor which controls the throttle valve may also be controlled by the same control unit which controls the fuel metering assembly, using a separate control loop.

Abstract: A gaseous fuel and air mixing venturi device adapted for retrofitting in a carburetor has a venturi body with a passage for air flow through the body, the passage having a throat of reduced cross-sectional area. The body has an axial fuel inlet port at a first end and fuel supply ports connected to the fuel inlet port and spaced around the throat for supplying fuel to the air flow passage for mixing with air flowing through the passage. The first end of the venturi body has mating seating formations for seating against corresponding seating surfaces of a gaseous fuel carburetor after removal of a spring mass air/fuel mixing section, and a fastener mechanism for releasably securing the venturi body in the carburetor, with the fuel supply port of the carburetor connected to the fuel inlet port of the venturi body.

Abstract: An emission control device for use with stationary or mobile gas-fueled internal combustion engines is described, which is placed in the fuel supply line and operates with full fuel authority. An oxygen sensor measures exhaust oxygen content. The valve internally houses a programmable microprocessor, a pressure transducer and a fuel flow conduit throttled by a balanced poppet valve. Signals to the microprocessor from the oxygen sensor, the pressure transducer indicating outflow gas pressure cause the microprocessor to motivate an actuator to move the valve within the gas stream and thus regulate the outlet pressure and also the gas flow rate to maintain a desired air/fuel ratio to the engine and keep exhaust emissions at an optimum level consistent with the engine operating load requirements and characteristics. Finite incremental control of valve position, preferably assisted by an internal position transducer, permits close control of the exhaust emissions.