Development Of Electronic Control System And Experimental Study For A Common Rail Diesel Engine

As a fuel system for diesel engine, Common-rail fuel system can improve the fuel economy and reduce the emissions. For better utilization of common rail fuel system and developing an advanced electronic-control diesel engine, it is necessary to develop a powerful electronic control unit (ECU) to flexibly control the injection pressure and injection quantity. The development of ECU includes three stages: hardware design, control strategy development and the parameters calibration. Because of the complex hardware structure of ECU and the long cycle of control strategy development and calibrations, this thesis concentrates on development of a PC-based electronic control developing system based on the author's group preliminary work.Based on the hardware and software resources of PC, combined with timing cards, data acquisition cards and Complex Programmable Logic Device (CPLD), the hardware platform enable functions such as generation and synthesis of control signals for injectors and pump oil metering unit, detection of diesel condition parameters. DOS system, C language, interrupt technology and the concept of structurization were employed for development of system software. Functions including human-computer interaction, common-rail pressure control and engine control were realized. With the hardware and software combined together, the system can flexibly control the injection pressure, timing, injection quantity and multiple injections. Moreover, the system is not only low in cost but also simple in structure and convenient in use, which will contribute to the development of a common rail diesel engine.In order to ensure injector's reliable work and good switching performance, we designed a power driver circuit with the MOSFET. The power driver circuit includes a MOS tube with good switching performance, a gate drive circuit and a drain to source voltage protection circuit. According to the analysis of switching performance of high-speed solenoid valve, effect of power circuit and discharge circuit on injection character is researched as a focus of experiment.Based on the powerful developing system, engine experiments were carried out to investigate the effect of EGR, later intake valve close timing and boost on the fuel economy and emissions. Results showed that in the middle load conditions at 1300 rpm, 1600 rpm and 1900rpm, EGR, later intake valve close timing, and boost can be integrated and coordinated to reduce the engine out emissions maintaining high efficiency.