Fuel injection pumps

Claim 1

A rotary distributor fuel injection pump comprising a rotary distributor member which is mounted within a cylindrical bore defined in a fixed body part, the distributor member defining a plunger bore in which is mounted a reciprocable plunger, the plunger during inward movement under the action of cam means displacing fuel from said plunger bore, a passage in the distributor member which receives fuel from the bore during the inward movement of the plunger, a plurality of angularly spaced outlet ports formed in the body and opening onto the surface of the cylindrical bore, a delivery groove on the periphery of the distributor member, said delivery groove registering with said outlet ports in turn during successive inward movements of the plunger, a plurality of angularly spaced inlet ports formed in the body and opening onto the surface of the cylindrical bore, the inlet ports and outlet ports being disposed in axially spaced planes respectively, said inlet ports communicating with a source of fuel under pressure, at least one inlet groove on the periphery of the distributor member and positioned to register in turn with said inlet ports to allow fuel to flow into said plunger bore during the time the plunger is allowed to move outwardly by said cam means, stop means for limiting the outward movement of the plunger, said stop means being constructed so that the extent of outward movement of the plunger depends upon the axial position of the distributor member within the cylindrical bore, first and second balancing grooves formed on the periphery of the distributor member for communication with the inlet ports and outlet ports respectively, a passage extending within the distributor member and interconnecting the balancing grooves, said balancing grooves effecting communication as the distributor member rotates, between each outlet port and an inlet port to stabilise the fuel pressure in the outlet ports.