Study of the Delivery Behaviour of a Pump for Common Rail Fuel Injection Equipments

This work deals with the delivery flowrate of a radial piston pump for common rail fuel injection equipment. At first, attention is paid to the volumetric efficiency of the pump, presenting basic formulas and reviewing common theory. A new efficiency model is proposed and considerations regarding the pump running under large pressure differences between suction and delivery and variable driving speeds are formulated in order to realize difficulties in pump filling. Later, a numerical model simulating the working behaviour of the pump is used to investigate the effects of variable inlet pressures under high delivery pressure and different driving speeds. Comparisons between numerical results and experimental data referring to the delivery behaviour of the pump are reported, as well as in-cylinder pressure diagrams, necessary to realize filling deficiencies quickly. The flowrate delivered by the investigated pump depends on both the inlet and outlet pressures. Increasing the driving speed beyond certain values does not result in proportional flowrate at pump delivery.