Simulation Methodology For Consideration Of Injection System On Engine Noise Contribution

The target of the investigation is the particular influence of a fuel injection system and its components as a noise source in automotive engines. The applied methodology is demonstrated on an automotive Inline 4-cylinder Diesel engine using a common rail system.This methodology is targeted as an extension of a typical standard acoustic simulation approach for combustion engines. Such approaches basically use multi-body dynamic simulation with interacting FEM based flexible structures, where the main excitation crank train, timing drive, valve train system and piston secondary motion are considered. Within the extended approach the noise excitation of the hydraulic and mechanical parts of the entire fuel system is calculated and subsequently considered within the multi-body dynamic simulation for acoustic evaluation of structural vibrations.The injection system is divided into its three main subsystems, the injector, the fuel pump and the common rail, and stepwise each of them is analyzed as a separate noise source. All three components are modeled as subsystems by 1D hydraulic model and finally combined to the complete fuel injection system. Moving mechanical components of the fuel pump are considered as additional multi-body components and connected to the timing drive. Fuel pump housing and the rail are modeled as Finite Element structures and attached to the engine model.Resulting transient loads are injector forces, pressure pulsation in fuel pump chambers and the common rail. Those are applied as external loads to the timing drive model and the power unit structure.The paper focuses on the modeling technique and presents the obtained results and a basic comparison with measurements.