Study Of Pressure Fluctuation On Electronic Controlled Common Rail Injection System Of Diesel Engine

Increasingly rigorous emission legislation and severe energy shortage force diesel to be developed for the objects of lower pollution, lower fuel consume and high power per weigh. However, the key to reduce emissions, improve the power of diesel and fuel efficiency depends on improving the combustion process of diesel, While improving the combustion process depends on well matching among the fuel injection system, the intake system and structure of combust chamber. Among these, the fuel injection system plays the most important role. And diesel engine high-pressure common rail electronic control injection system is the most effective in emission reduction and engine performance improvement among all of the fuel injection system currently. Since dynamic pressure characteristic especially pressure fluctuating inside rail directly refer to achievement of perfect injection rule, the study of rail pressure fluctuating have been one of current hotspots in high-pressure common rail system.The thesis established the flow model based on one-dimensional, unsteady, compressible, Navier-Stokes equations, and discrete the governing equations using a finite-volume formulation. Then founded the numerical models of fuel pump, rail and injector according to the structure of fuel injection system, and specified the numerical models as fluid model boundary. Above models were checked up by testing results, and the influence of different parameters in common rail system on pressure stability was simulated.In this paper, the models of the common rail fuel system are created with HYDSIM of AVL company. The models are validated by test results. The main work is as follows:1. A common rail system is used as the prototype, with stable common-rail pipe inside of pressure for point of departure, it is investigated and also discussed on key structure parameters, aiming at common-rail pipe inside pressure fluctuant of impact.2. Affects of high-pressure volume and common rail pipe length-diameter ratio in common rail system on the fluctuation of common rail pressure are studied. Principle of high-pressure volume design is indicated here. And present high pressure cubage design considerations.