Fuel injection pumping apparatus.

摘要

A fuel pumping apparatus for supplying fuel to an internal combustion engine has an injection pump 10 supplied with fuel by a low pressure feed pump 14 through an adjustable throttle 16. A fluid pressure operable piston 12 is movable against the action of a spring 13 to control the timing of delivery of fuel by the injection pump. Fuel under pressure is applied to the piston through a first fixed orifice 20 from the feed pump. A second fixed orifice 22 and a variable orifice 23 are connected in series between a drain and the downstream side of the first fixed orifice. In parallel with the first fixed orifice is a constant pressure drop valve 26 which maintains the pressure drops across the first fixed orifice substantially constant when the pressure drop has risen to a predetermined value.