Study On The Control Device Of High Pressure Common Rail System In Diesel Engine

The increasing importance attached to the environment worldwide in recent years has accelerated the research and development of clean diesel engine. Among all kinds of advanced technology that reduce emissions, electronically controlled common rail injection system is viewed as the best one. High pressure common rail injection system can reduce the emission of soot and particles while improve the overall performance of diesel engine at the same time. In order to fulfill components testing and performance analysis, the pressure regulating valve and the solenoid valve for common rail systems need to be controlled during the development, calibration and testing process to simulate various working conditions by regulating oil pressure and injection rate efficiently according to the requirements of experiment. Therefore, it is quite meaningful and necessary to produce a flexible and accurate control device of high pressure common rail system in diesel engine for laboratory use with good generality and affordable price.The device designed, using PWM wave as the control signal, can change the current waveform and current value by regulating PWM's duty cycle-flow rate. This method is quite flexible with good generality. Through the regulating of driving circuits for pressure regulating valve and injector solenoid valve, we could realize the stable regulation of oil pressure in common rail system and flexible control of injection timing and injection rate. Moreover, the writer has designed reasonably the PCB of each circuit module and set adjusting buttons and key control, balancing the volume of the device and its function and reliability to meet the needs of different situations.The writer, after the experiment on the common rail oil pressure and the injection rate using the control device designed, analyzed the common rail oil pressure and fluctuation when it changed with the change of PWM's duty cycle-flow rate. The influence on the injection rate when the time gap between pilot and main injections changed, the power-up current and holding current of main injection changed, or the common rail pressure and the duration of main injection differed, was also studied.Last but not least, the writer designed the circuits of the negative voltage driving module for the injector solenoid valve, the conversion module between positive and negative power and the driving module for the injector solenoid valve and proposed some improvement suggestions to optimize the accuracy, reliability and generality of the control device.