Research On Measurement Method Of Vehicle Fuel Economy Based On Virtual Instrument

This is a disquisition on vehicle fuel economy measurement method, applicable for vehicle with Electronic-controlled Fuel Injection system, with the characteristics of directly collecting electric signals and computing fuel consumption of 100-kilometer without changing the oil supply system.This paper analyzed existing vehicle fuel consumption measurement method and Electronic-controlled Fuel Injection system principles, and put forward measurement algorithm on fuel consumption of 100-kilometer which is based on measuring injection pulse-width. The algorithm adopted three related signals, including injection driven signal,engine ignition signal and vehicle speed signal. Through collecting injection driven signal, we figured out single injection pulse-width;Through collecting engine ignition signal,we figured out engine speed and inject cycle, then computed single injection quantity by entering injection pulse-width and dynamic fuel injection coefficient, lastly we got total injection quantity by summing up single injection quantity;Through collecting speed signal, we calculated speed and distance, and eventually we got the average fuel consumption of 100-kilometer by integrating total injection quantity.As required by algorithm,this paper researched injection dynamic characteristics, and designed injection dynamic fuel injection coefficient measurement device.By fitting experiment figures, we got the dynamic fuel injection coefficient changing with pulse-width curve, and adopted this changing discipline to measurement programming, which can convert pulse-width to injection quantity.This paper developed fuel consumption measurement system based on computer testing techniques. This system applied upper-lower computer structure,lower computer used data acquisition card, and with signal conditioning device which was designed by myself, it realized the objective of signal conditioning and collection;Upper computer used PC,we used LABVIEW as development platform,developed fuel consumption measurement software. Upper-lower computer adopted USB communication protocol.This system can measure injection pulse-width,engine speed and vehicle speed,computed and displayed vehicle fuel consumption of 100-kilometer.Lastly, this paper verified the fuel consumption measurement system on two types of automobiles in experiment environment, which suggested that fuel consumption measurement method based on injection pulse-width is workable and effective.