USE OF CERAMIC SLIDING SYSTEMS IN A PROTOTYPE GASOLINE PUMP WITH OPERATING PRESSURES OF UP TO 80 MPA

摘要

The fuel consumption of modern combustion engines can be significantly reduced through the use of gasoline direct injection (GDI). As the time for mixture preparation in GDI engines is very short, the fuel has to be injected at high pressure into the combustion chamber. Modern injection systems provide an injection pressure of up to 20 MPa, whereas investigations performed at the Karlsruhe Institute of Technology have shown strong potential for reduced pollutant emissions by increasing the pressure to 80 MPa. However, the low lubricity of gasoline causes severe friction and wear in the high-pressure pump at fuel pressures above 20 MPa. The use of ceramic components in the sliding systems should help to overcome this limitation. A three-piston radial pump based on ceramic sliding systems that delivers fuel at up to 80 MPa has been designed at Karlsruhe Institute of Technology. The prototype is based on the knowledge accumulated during former investigations performed on a single-piston pump. It is fitted with pressure and temperature sensors in each cylinder and a torque sensor on the driveshaft in order to measure its efficiency with various material combinations in its sliding systems. The results show that the use of silicon carbide or Sialon enable operation at injection pressures of up to 80 MPa with very good mechanical efficiency and low wear.