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: Systems and methods for continuous automatic adjustment of a control set point of an air-fuel ratio controller of a rich burn engine so as to maintain emissions within a desired range. In an embodiment, a NOx sensor is placed in the exhaust outlet from an exhaust catalyst and the NOx exhaust sensor output is continuously monitored while adjusting the control set point between rich and lean in order to minimize the output from the NOx sensor. Corrections may be continuously made to the set point during operation of the engine to compensate for changes in environmental conditions, engine loads, and other factors.

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.