The Design Of High Pressure Common Rail Injection System Test Platform And The Correction Of Fuel Quantity Deviation

The diesel engine presents a better fuel consumption and power performance whencomparing with the gasoline engine. With the development of high pressure common rail,the advantage is even more obvious. However, the development of diesel engine is facingwith great challenge under the more and more rigid emission roles and the PM and NOxemissions are dominant in hindering the development of diesel engine. The high pressurecommon rail system is developed at reasonable speed for its excellent controllableperformance. Although the system is already sophisticated nowadays, there is a greatdistance with the foreign technique in China. The development of the control strategy aswell as the realization of precise processing technic has to be improved.In this paper, the method of different injection rules realization as well as the influenceof the influence of the injection rules on the in-cylinder combustion process is introducedbecause the precise electronic control is the precondition of the realization of suitableinjection rule. Plenty of articles concerning the variation of engine working process are read.The variation between cylinders is the primary cause for the craft vibration and the noisegeneration so that the riding comfort and the engine duration are damaged and the economicand emission performances are also influenced. It can be concluded that the improvement ofuniform control of various cylinders is a reasonable method for engine performanceimproving, meanwhile, the accurate control of the injected fuel quantity is the basement.For the purpose of checking the deviation fuel quantity injected and amending it, ahigh pressure common rail system test bench, motivated by a frequency modulation motor,is designed. A domestic open control platform is implemented for the reason that themodification of the relevant control strategy from BOSCH is not supportable. The collectionof the sensor signals and the actuation of the actuator can be realized. Relevant programsare designed for the injection and rail pressure control. Four injectors that have been used for a period of time are used for research. Theexperiment results show that the deviation between cylinders is above10%, as a result, theworking uniformity between cylinders is influenced to a great extant. An injection widthcomposition control method is designed for the amendment of injector inconsistency. Thecycle injection quantity is measured under a wide range of rail pressure so that the injectionquantity curve is acquired. Then the average value of the fuel injection between the fourinjectors is calculated and the corresponding curve is drawn. The base MAP and thecompensation MAP are set according to the deviation of each injection for thecompensation of fuel injected from each injector. A limitation of compensation is setaccording to the inflection point of the injection quantity curve under different rail pressure.The experimental results show that the deviation between injectors can be controlled below5%with the compensation. The injection performance is almost as reasonable as the newinjectors.