The Control Strategy Of Start And Idle On2.0T High Pressure Common Rail Diesel Engine

In the spring of2013，the phenomenon of the whole country’s continuouslyimpacted by haze weather which does harm to people’s daily life and health and causemore and more people to purchase environment friendly vehicles with low emissionsand fuel consumption. Currently, HPCR diesel engine is one of the most popularresearch directions with it’s independent rail pressure of the engine speed, flexible andadjustable injection rule and excellent economy, power and emission characteristics.Because of the late start researches on HPCR diesel engine in our countriescompared with the developed countries, we have a weak foundation about it and have toinduce the core technology from the foreign countries. The optimization of Start and idleconditions are obviously important to diesel engine as the two conditions’ closeconnection with the engine’s emission, economy and power characteristics. The researchaim to propose the start and idle condition control strategy for a2.0T HPCR dieselengine with the Bosch company’s EDC17control system to optimize the engine’s startand idle performance through the test line which is based on the project Study of NovelCombustion System on2.0T HPCR Diesel EngineFirst of all,distinguishing overall diesel engine operating mode to make out thestatus of start and idle condition in integral engine control strategy. Then explaining thecalculation process for start and idle injection, on the meanwhile providing the way ofcalculating start and idle torque and the way of translating torque into injection quantity.Lastly, the paper list the process of injection mode control for the reason that it isessential to start and idle control strategy.The start test is completed based on the start control strategy. Comparative testsabout injection times, starting injection speed and constant value of start function aregiven after the demand torque map of start is set out. The comparative tests aboutdifferent start injection ratio of three times injection for start performance, the orthogonal tests of start injection time and other tests are performed.The idle test is completed based on the idling control strategy. In order to comparethe influence which is caused by different injection mode and idle target speed on idleperformance three comparative tests about different starting injection ratio of three timesinjection for starting performance are given. Also the orthogonal tests of idle injectiontime and comparative tests about different PI coefficients for idle stability are performed.The study found that using three injections (double pilot injections, a main injection)is in favor of shortening start-up time, reducing the starting HC, CO emissions, also thestarting speed’s cycle volatility and improving idle stability and economy. The higherthe starting spray speed is, the better starting performance is, but this subjects to theperformance of the battery and starting motor. It found that the different injection ratioaffects the speed of start and the stability and economy of idle speed (the difference ofstability and economy up to about17%) by three comparative experiments aboutdifferent fuel injection proportions. When using the injection proportion of20%-20%-60%, starting and idling, it has the best performance. Through orthogonal experiments,it also found that tiPiI1the time between pilot injection1and main injection has thelargest impact on its starting time, idle stability and economic, then follows the angle ofmain injection, and last tiPiI2the time between pilot injection1and pilot injection2hasthe minimal impact. Comparative experiments found that reasonable kp, ki help toimprove idle stability, but have little effect on the idling economy.