Fuel pumping apparatus

Claim 1

A fuel pumping apparatus for supplying fuel to an internal combustion engine comprising a rotary distributor member housed within a body, a bore in the distributor member and a plunger therein, a cam for imparting inward movement to the plunger to displace fuel from the bore, a delivery passage communicating with the bore and positioned to register in turn with a plurality of outlet ports in the body during successive inward movement of the plunger, means for filling the bore with fuel to effect outward movement of the plunger and spill means operable to spill fuel from the bore characterised in that said spill means comprises a cylinder defined in a part of the distributor member, a piston slidable in the cylinder, a port formed in the end wall of the cylinder and communicating with the bore, a seating defined about said port, a projection formed on the end face of the piston presented to said end wall, said projection being shaped for co-operation with said seating, resilient means biasing said piston so that the projection engages with the seating to prevent fuel flow through said port into an annular space defined about the projection and between said piston and said end wall, a drilling extending axially into said piston towards said end face, a passage connecting the inner end of said drilling with said bore, a plug slidable in said drilling but located against axial movement, the end area of the plug being substantially equal to the area of the seat, and means operable during the inward movement of the plunger to impart axial movement to the piston against the action of the resilient means thereby to lift the projection from the seating to allow further fuel displaced by the plunger to flow into said annular space.