Wang Weihua

Simulation study on injection characteristics of a new type of DME injector

According to the low pressure common-rail fuel system of dimethyl ether (DME) engine with controllable premix combustion, a new type of dimethyl ether common-rail injector has been developed, which can solve the problems about wear and leakage of plunger and barrel assembly in traditional fuel system. The hydraulic dynamic simulation model of the injector has been established. In order to find out the influence on fuel injection characteristic and response characteristic, some parameters of the injector have been researched, including stiffness of the spring, volume of the injecting chamber, diameter of spray holes and the number of oil hole. The research shows that the injector has stable injecting flow, there is favorable linearity relation between injection quantity and pulse width of oil supply; the stiffness of spring and the volume of injecting chamber have great influence on the injecting flow; diameter of spray holes and the number of oil hole can only affect the value of injecting flow, and affects little on injecting characteristic.

Dynamic analysis for slider-crank mechanism of engine at the presence of nonlinear friction

This research is to introduce a precise algorithm, which can obtain numerical values of dynamic analysis for hinges of slider-crank mechanism in engine with nonlinear friction. Nonlinear equations were solved on the base of gradient method. The function of control convergence in the program was presented, which could overcome slow convergence of gradient method in great degree. The calculating results show that the driving moment and reactions were obviously higher than corresponding values with neglectful friction. In order to check the reliability of nonlinear equations established and algorithm obtained, the inertia force and moment were ignored, the calculation was simplified into the special one. The results were compared with data in Reference [2], which showed a close agreement with the corresponding values. The paper could play a certain role in the development of nonlinear analysis for slider-crank mechanism of engine.