Fuel Return Line Optimization on a 5-Cylinder Engine

摘要

The main function of a fuel return line system on a common rail diesel engine is to deliver the excess fuel coming from injectors, fuel injection pump and high pressure common rail to back the fuel tank following some specific chassis fuel line components like fuel cooler, fuel filter and fuel delivery module. The return pipe diameter, surface roughness, fluid properties, elbows and bends, and pressure drop at these components on return line are the main parameters effecting fuel pressure and flow characteristics. Due to the improper selection of some of these parameters, sudden pressure increase may happen on critical points. Hence, the design of the fuel return line is to keep the monitored Fuel Injection Pump (FIP) seal back pressure within design specifications on any customer usage or engine operating condition. In order to present an optimized and robust fuel return line system on a 5 cylinder diesel engine; in terms of flow and pressure requirements of critical points on engine and vehicle line especially on fuel injection pump, a Flowmaster Model for the fuel return line system for different operating conditions and design-wise scenarios have been developed and studied under cold and hot fuel temperatures. The predictions are then compared and verified with the initial failure findings and the measurements performed on the vehicle. Simulation results are then verified to the values observed with the controlled replication testing completed on dynamometer different scenarios without cost and time constraints.