A Study On An Electronically Controlled Unit For Engine Fueled With Dimethyl Ether

On grounds of air pollution and energy crisis, the reformation of engine is pressing to decrease emission and increase the economics of engine. Becase of diesel engines have been used in many fields , the research of alternative fuel of diesel is significant. As one of the new alternative fuel with its many merits, the DME is thought to be the most optimistic alternative fuel of diesel in the 21th century . On account of the DME character in itself, essentially, many conundrums have been soloved, But the most important reformation is injection system, with this, many an authorities around the world have done quantities of research. On the basis of having done a lot of copparison between Dimethyl Ether and diesel, we have successfully designed a new injection system ie PRVI (Pump-Rail-Vulve -Injector), At the same time, we have also been developing a new electronically controlled unit(ECU).Due to meet the injection and administration of DME engine efficiently , the paper introduces a new electronically controlled unit (ECU). The ECU consists of two PIC16F877 micro-controllers, sensor processing circuits and driving circuits. First the required operating parameters are registered by sensors and converted into numerical signals, and then the injection pulse width and injection advance angle are acquired according to the MAP. Redundancy design and module circuit design have been used, and the adaptability to environment, self-protection and heat release are completely thought over.The control software is compiled with ASM language, the software includes the control program under different situations, monitor program and signal processing program. In order to improve the software extension and modification, the hardware and software are made with sub-program and layer structure model. The idea of a layer-based architecture is that lower layers offer all the services needed by the higher layers.In order to evaluate the ECU is feasiable or not, the computer simulation, analogue and oil pump test-bed experiment have been carried out. The results showed that the ECU can perform three tasks: to display the measured data received from the sensors, to process data and basic condition control for DME engine.