High Pressure Fuel Pump for Gasoline Direct Injection based on Ceramic Components

Modern direct injection spark ignition engines (DISI-engines) require increasing fuel-injection-pressures in order to accelerate mixture preparation. Therein the fuel-pump is an essential component. Non-conventional materials offer a high potential to realize high pressure combined with low wear and friction. An exemplary high pressure fuel pump was developed in order to evaluate the use of different combinations of ceramic materials and steel as sliding parts. Forces and friction coefficients can be retrieved as a function of the crank angle in the sliding contacts. The leakage in the gap between cylinder and piston was analyzed and an analytical model was developed. Important effects of clearance, stroke frequency and surface roughness on forces and friction coefficients are presented for different combinations of materials and fuels.