GAS SUBSTITUTION CONTROL SYSTEM AND METHOD FOR BI-FUEL ENGINE

摘要

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.

主权项

1. A method of controlling gas substitution ratio in a bi-fuel engine, comprising:
calibrating a bi-fuel engine having a gaseous fuel input and a non-gaseous fuel input over a range of engine loads to determine the gaseous fuel flow and corresponding non-gaseous fuel flow to produce predetermined gas substitution ratios (GSR) over the calibrated load range; storing the calibration data in a data base; detecting current non-gaseous fuel flow to the engine; using the stored calibration data to determine the gaseous fuel flow corresponding to the current detected non-gaseous fuel flow; controlling a gas metering assembly to produce a gaseous fuel flow to the engine corresponding to the determined gaseous fuel flow computed from the stored calibration data; and continuing to monitor the current non-gaseous fuel flow to the engine and adjusting the gaseous fuel flow in response to variations in detected non-gaseous fuel flow in order to maintain the GSR at or close to the predetermined level and compensate for variations in detected non-gaseous fuel flow.