Search Results

Fuel rails with integrated damping effect (FRID's), developed for MPI returnless fuel supply system s, effectively reduce fuel pressure pulsations without pulsation dampers (P/D's). One of the remained issues on FRID's is discussed in this paper. Pressure pulsation peak(s) at certain engine speed(s) (P/P engine speed) is significant issue in some cases. Intensive study revealed that the resonance speed is determined by the pressure change period (P /C period) at oil-hammer, induced by an injector open or close. The P/C period control parameters such as the sound speed in a fuel rail were identified, and suggested configurations to shift a P/P engine speed out of the typically used range in engines were established.

Fuel rails (FRs) with integrated pulsation dampers prevent undesirable cabin noise. Such fuel rails were studied through a test vehicle evaluation on MPI returnless fuel supply systems. Among the alternative shapes of steel FRs, it was found that a flat or high aspect ratio rectangular cross section FR best absorbs the fuel pressure pulsations. In addition, the effect of the air-fuel ratio (A/F) was experimentally studied on pressure pulsation absorption in V and in-line engines.

Diesel engine common rail systems are expected to reach higher pressures, which require higher internal fatigue strength of the rail. The primary objective of this study is to improve the rail strength by modifying its structure. In this paper, a prospective rail construction capable of handling higher pressures is proposed. At first, a current generation rail was evaluated for pressure cycle durability, in order to analyze its strength. Then the optimized structure was sought via FEM analysis, which revealed that a flat internal surface significantly improved strength. The results were confirmed by pressure cycle tests.