Study On Controlled MAP System Of High Pressure Common Rail Diesel Engine

MAP is an important part of control strategy, the control effect and the engine performance would be determined by the MAP data calibration. Control strategies for different function are constituted by different MAP, at the same time, mutual influence and restriction are existing among MAP parameters. With the increasingly powerful of electronic control system, control parameters and MAP is increasing exponentially, this brought certain difficulty to calibration. Research on MAP composition and the building of MAP system for high pressure common rail diesel system can make a significant guidance for calibration and strategy developing.On the basis of control strategy analysis of high pressure common rail system, according to the physical meaning of the MAP, by using the classification research method of different function, MAP composition of fuel injection control, rail pressure control and air control system were studied. According to the study on the relationship between the MAP parameters, the MAP system were established, and the basic MAP of MAP system was developed. Under the guidance of the MAP system, calibration experiments were made to the main injection timing MAP, rail pressure MAP, pilot injection quantity MAP and pilot injection timing MAP, then the optimum dimensional MAP were determined, coMParison was made to analysis how the injection system MAP parameters influence the engine external characteristic performance before and after optimization. The results are as follows:(1) The MAP parameters of injection control were divided into injection release MAP, basic control parameters MAP, control parameters correction MAP, limit MAP and other function MAP. The MAP parameters of rail pressure control were divided into basic control parameters MAP, control parameters correction MAP, limit MAP, controller parameters MAP and other function MAP. The MAP parameters of air system control were divided into five categories:basic control parameters MAP, control parameters correction MAP, limit MAP, controller parameters MAP and other function MAP.(2) There were a selection decision relations among different MAP parameters. The injecton release MAP involved in the control is determined by the serial number of engine temperature domain which is output by release selection MAP. The main injection timing MAP involved in the control is determined by the serial number of pilot combination.(3) There were a successively decision relationships among different MAP parameters. The total fuel amount from torque-fuel MAP is the input of rail pressure MAP, the value of the rail pressure is determined by this input. Rail pressure is the input of energizing time MAP and injector electro-hydraulic delay MAP; as a input of fuel pressure fluctuations correction MAP, the electro-hydraulic delay can determined the pressure fluctuation correction value.(4) There are some constraint relationships between the main injection quantity and pilot injection quantity MAP, post injection one quantity MAP and post injection two quantity MAP. If the latter ones was increase, the main injection quantity would decline. Part of MAP parameters also have parallel relationships.(5) According to the guidance of MAP system, the rail pressure MAP were selected as primary calibration parameters. The angle range adjusted of main injection timing were determined by the determine relationship between torque-fuel MAP, rail pressure MAP and energizing time MAP. When calibrate the pilot injection timing, we need to consider the injection angle of pilot injection quantity. The angle adjusted range of pilot injection timing were determined by the determine relationship between torque-fuel MAP, rail pressure MAP, energizing time MAP and pilot injection quantity MAP.(6) After optimaization, the engine torque of low speed was decline slightly; in the condition of middle and high speed, the torque was invariable; the economy and smoke emission was improved under the whole working range, especially in the low speed conditions, the smoke was greatly improved; The NOx emission was reduced by ten percent during the whole external characteristic.