A study on cycle fuel injection quantity variation for a diesel engine combination electronic unit pump system

Abstract

A new fuel injection equipment, combination electronic unit pump was developed to make diesel engines compliant with China’s new laws on emissions. Combination electronic unit pump system is a complex assembly constituting of mechanical, hydraulic, and electrical magnetic components. Combination electronic unit pump system includes several electronic unit pumps and mechanical injectors. Cycle fuel injection quantity variation influences product performance and defines its quality of qualification. A numerical model of the combination electronic unit pump system was developed in AMESim environment to create a design tool for engine application and system optimization. Simulated results obtained from this numerical model were validated through experimental tests conducted under the conditions same as numerical model. The results are quite encouraging and consistent with model predictions. Influences of parameters, including variations in supply fuel pressure, cam velocity, plunger-matching clearance, peak control current, anchor residual clearance, valve-matching clearance, valve lift, injector opening pressure, nozzle-flow coefficient, and injector needle lift, on cycle fuel injection quantity variation were analyzed in AMESim simulation environment and verified through experiments. The quantitative percentage indexes of the influence of injector characteristic, valve characteristic, plunger characteristic, and low-pressure supply fuel characteristic parameters on cycle fuel injection quantity variation range from 44% to 34%, 20% to 35%, 32% to 19%, and 4% to 12%, respectively, at a cam rotational speed of 500–1300 r/min.