| 摘要 |
<p>A control system for internal combustion engines, including a first conduit for the flow of intake air, and a second conduit for the flow of natural gas to be mixed with the air for combustion. The flow of the air is variable over a range of mass flow rates during operation of the engine and an air mass sensor is positioned to sense the mass flow rate in the first conduit and generate a first flow rate signal indicating the mass flow rate. A natural gas mass sensor is positioned to sense the mass flow rate of the gas in the second conduit and to generate a second flow rate signal indicating the mass flow rate of the natural gas. The first and second flow rate signals are compared in an electronic controller that generates a control signal if the first and second flow rates vary from a predetermined ratio. The ratio is selected to provide a substantially stoichiometric ratio of air and natural gas. A valve is provided to adjustably control the flow rate of the natural gas in response to the control signal to maintain the preselected ratio. A sensor and shutoff valve are also provided for terminating the flow of the natural gas when its pressure falls below a predetermined pressure, allowing immediate flow of gasoline to the engine, thus assuring smooth, continued operation of the vehicle. A throttle body has a natural gas distribution ring in the throat of the body and provides a curtain flow of gas.</p> |
