HIGH-PRESSURE FUEL PUMPS - THEIR DESIGN AND EVOLUTION

The swash plate pump has been developed from an N ROOT Q (N equals maximum speed and Q equals the flow at this speed) of 2 with 250 hours life up to an N ROOT Q of 7 multiplied by (times) 5, with time between overhauls of 12,000 hours. It has therefore reached the economic limit of development, unless some significant material development occurs. This pump is, however, still the first choice if very high pressures are required. The radial variable stroke pump is at an early stage of development, and will be used where high speed and high pressure are required. The twin pinion gear pump has been developed up to an N ROOT Q of 13 with up to 15,000 hours between overhaul. There is, however, scope for further improvement as shown by the latest porting design. The internal gear pump design provides the basis for a significant improvement on performance and life, but will most likely be overtaken with the centrifugal pump. The centrifugal pump will eventually be developed and, if the first theoretical analysis proves to be achievable in practice, a completely new approach to engine fuel systems will result.