Fuel injection pump with auxiliary control system

摘要

A fuel injection pump having an inlet metering valve for supplying a metered quantity of fuel from a transfer pump to a pumping chamber and an auxiliary control system for limiting the maximum quantity of fuel supplied to the pumping chamber via the inlet metering valve. An auxiliary valve piston is axially shiftable by the transfer pump outlet pressure to provide a variable restriction between the transfer pump and metering valve for establishing a maximum fuel quantity limit within a predetermined speed range of the pump. A low-speed fuel passage is provided in parallel with the variable restriction for establishing a maximum fuel quantity limit within a lower speed range. The back pressure chambers of the auxiliary valve piston, a transfer pressure regulator piston and a pump timing piston are connected to a pump housing cavity to equalize the back pressures in those chambers at the same constant pressure maintained by a housing pressure regulator.