Research Of Rail Pressure Contol Strategy For Multi-condition Of High Pressure Common Rail System Of Diesel

Following environmental issues have maked the diesel vehicles emission standards stringent increasingly, High pressure common-rail electronic control fuel system become the latest development trend. As one of the key technologies of high pressure common-rail system,Rail pressure contol has a great impact on diesel engine power and emissions.As the same time, rail pressure contol has a certain degree of difficulty for the diesel is a multiple variable system with non-linear, big time varying and strong coupling characteristics. In this paper, by the method of combining theory and experiment,we have in-depth researched rail pressure contol strategy of BOSCH-CR System which is configured on GW2.8TC(4JB1) diesel vehicles. The major work as follows:Firstly, analysed the overall structure of BOSCH-CR fuel system. Researched the structures and mathematical models of its key components, and then, finished overall design of Rail Pressure Contol system.Secondly,finished hardware design of rail pressure contol system,included drive circuit of MeUn and acquisition and processing of rail pressure signal.And then, researched some rail pressure control algorithms.Inclouded effect on rail pressure control precision using different acquisition ang control timing;desiged rail pressure signal filter algorithms;researed PID algorithms and method of PID parameter self-tuning; desiged the strategy of acquiring targert of rail pressure;at last, acquired the general program of rail pressure control.Thirdly, carried out lots of experiments on pump test bench and engine stand.quantitative studied the rail pressure's effect on the diesel engine power and emission;calibrated maps which were related in rail pressure control;at the same time,modifed the PID algorithm for steady conditions to Guarantee control precision within±20Bar,and have good stability.Finally, in order to meet the requests of fifferent conditions,researed contol strategy for multi-condition and carried out lots of engine stand experiments. Experimental results show that, diesel can start quickly and stable at idle ,has no"stalling"or"Traveling";at the transient conditions,have good following performance, error is within 5% of the maximum rail pressure and have no overshoot; simultaneity, by compared to the data of the BOSCH original machine, proved the contol strategy met the require of diesel engine power and emissions.