Study On Fuel Injection Control Strategy And Optimization Of The Rail For High Pressure Common Rail

As a type of clean diesel engine, electronic control common rail diesel engine is one of the best choices in save energy and environments protect conception. The research of fuel injection control strategy and optimization of the rail for High Pressure Common Rail (HPCR) has a very important significance to strengthen the operation stability, to improve the fuel calculation precision, to optimize the engine performance, to save energy and decrease wastage. In this dissertation, the fuel injection control strategy and Multidisciplinary Design Optimization (MDO) for rail had been systematically studied by the support of "Development on New Generation Energy-saving and Environment-protect Efficient Internal Combustion Engine for Car" (the National High Technology Research and Development Program ("863"Program) of China) and "Development and Application on Key Technologies for Clean and Energy-save Diesel Power System Used on Passenger Car"(National Key Technology R&D Program).The main work in this dissertation is as follows:1. By fully demonstrating and comparing the multiply injection coordinate control strategies in existence, the control strategy had been designed as environment layer, limitation layer and setup layer, using hierarchical and module structure. By adapting fuzzy neural network technology, multiply injection dynamic combination model had been built. The model had been tested in starting, normal and after run working conditions.2. Put up the definition and calculate method for internals between two injections. Based on the high pressure common rail test pump bench, open ECU and high speed photography, the effect of fuel spraying and atomizing by internals between two injections had been researched.3. Based on neural network and portion differential PID, a new control strategy for rail pressure had been brought forward. This method associated engine working condition and the PID parameters together, achieved control the rail pressure in all the working conditions, obtained certain precision, and decreased rail pressure oscillation effectively.4. According to the fact of pressure oscillation in rail tube and the working principle for high pressure oil pump and electrical control injectors, with the intervals from the end of last injection to the start of next injection and the hysteresis between electronic control and hydraulic together, the backoff algorithms of pressure oscillation for injection quantity had been put forward. This method can make the injection quantity balancer and more homogenous.5. By MDO method, the multidisciplinary characteristics of rail tube had been analyzed. Optimization design for rail in whole situation had been achieved through winkling the relationship between kinds of parameters and the optimum rail volume. By doing this, the economy and stability for rail had been improved further.There are main conclusions in the dissertation:The applicability of multiply injection dynamic combination model is good enough to satisfy the demand of ECU.The internals between two injections have important effects on fuel spraying and atomizing. When the injection frequency is 20Hz, the fuel spraying and atomizing performance is the best on the condition of the equipments in this dissertation.The pressure control method with neural network and portion differential PID put forward by the author not only provides the new means to control common rail pressure, but also provides new thoughts to set PID parameters, therefore it has higher theoretic values.The backoff algorithms of pressure oscillation for injection quantity based on last injection inaugurate a new field to compensate injection quantity, and can instruct scientifically to adjust the injection quantity and decrease the deviation caused by pressure oscillation so as to optimize the operation parameters.By MDO method, the rail tube volume is decreased by 1.07%, pressure oscillation is decreased by 16.7%, and the mass of rail tube is decreased by 6.8%. The whole performance of HPCR system has been improved largely.The research work developed by author had been successfully used on HPCR test pump bench. The running practice showed the control strategy and optimization rail can decrease the pressure oscillation and compensate the injection quantity effectively, and can make the operation of HPCR stabilization and optimization so that can improve the running efficiency of HPCR.It can be said that the research work offers a new way to upgrade the HPCR. Thus the research results have higher theoretic and utility value, and can been extended to apply in the same HPCR in our country.