Mitigation of Noise and Vibration in the High-Pressure Fuel System of a Gasoline Direct Injection Engine

In the past decade, deployment of high-pressure direct injection systems in petrol engines has dramatically increased, mainly due to the advantages for fuel economy. At the heart of a gasoline direct injection system lies the high-pressure fuel pump, which pressurizes the petrol to more than 30 times compared to that of conventional port fuel injected engines. The high-pressure system is driven mechanically by the cam-shaft, and results in generation of inherent undesirable noise which renders the sound quality of the traditionally-silent petrol engine similar to that of a common-rail diesel engine. This paper gives a comprehensive review of the measures developed to mitigate the inherent noise of the high-pressure direct injection system. For the high-pressure pump, Design of Experiments was employed to enable the improvement of the mechanical design attributes of the outlet valve. Model-based control design and advanced control algorithms were developed and deployed on the real-time controller to reduce the noise of the solenoid valve which controls the flow through the pump, hence reducing the inlet valve's ticking noise. The high-pressure fuel is delivered from the pump to the combustion chambers via the high-pressure fuel rail and injectors: when the latter are energized, they induce significant structure-borne vibration in the engine block which in turn results in undesirable noise: this was mitigated by developing an isolation system for the fuel rail and a suspension mounting scheme for the fuel injectors. Our paper presents the details and merits of these component- and system-level developments, each of which resulted in noise reductions of 2 - 6 dB(A) at the various characteristic frequency bands of the gasoline direction injection system during engine idling conditions