Research And Development Of ECU For High Pressure Common Rail Diesel Engine

The environmental issue, shortage of petroleum resources and rapidly expansion of microelectronics technology are the main reasons of the rapidly development of diesel engine electrol system. The flexible pressure control of high-pressure common rail, adjustable fuel injection time, adjustable injection pulse and injection frequency adjustable in a single loop make diesel engine at low emissions, low oil consumption and high power situation.This topic is based on the ECU is the hardware core of the high-pressure common rail electrical control system, after studying the high-pressure common rail diesel engine’s actuators and sensors’working parameters, and at last design the ECU hardware for small diameter four cylinder of high pressure common-rail diesel engine electronic control system.In the project design of ECU hardware, mainly including the MCU minimum system circuit, booster circuit, high and low side switch driving circuit for injector, half bridge driver circuit for fuel metering unit, half bridge driver circuit for EGR’s actuators, relays’switch type drive circuit, preheating plugs’switch driving circuit, hysteresis comparison circuit for crankshaft, camshaft signal hysteresis and other sensor signal processing circuit. In the design of PCB wiring link, the ECU circuit board was produced after thinking about the size of power of actuators and ground wiring. After welding the ECU board by hands step by step, do the functional verification of ECU board and finally do the experiment at engine test bench.Through the bench test, the results show that the designed of high pressure common-rail diesel engine ECU board combined with the software control strategy can meet to control small four-cylinder machine, and the designed of hardware is feasible. The fuel injector can be good controlled by the driving circuit, the electromagnetic valve coil current from 0 A to 18 A costs about 100μs in the mian spray stage, the mian injection time can smooth continuous above 10 ms, the injection rate could up to 6 times with stably current waves in a single cycle, have no waveform mutation and abnormal injection during the injection; The pressure in the rail can be adjusted through the fuel metering unit driving circuit within the scope of the pressure control; The signal processing circuits of crankshaft, camshaft and other sensors can give the accurate working informations to the ECU; During the experiments of startup, idea speed and deceleration, the engine could easily start,the speed and rail pressure could be controlled smoothly, the injectors can achieve the multiple injection capacity. There have no situations of serious knocking cylinder and smoking during experiments.