Fuel injection nozzles

Claim 1

A fuel injection nozzle for use with an internal combustion engine comprising a body having a fuel inlet which in use, is connected to a high pressure source of fuel, a resiliently loaded valve member slidable within the body, said valve member defining a surface against which the fuel under pressure can act to lift the valve member to an open position against the resilient loading to allow fuel flow to an outlet orifice, a bore extending through the body and connected with said inlet, the bore defining a reduced valve guide portion at its outer end, said valve member being located within said bore and having an outer end portion guided for movement by said valve guide portion, the valve member being loaded by said resilient means in an outward direction and said orifice being formed in the outer end portion of the valve member characterized in that the orifice comprises a single drilling the downstream end of which opens onto the exterior surface of said outer end portion of the valve member, the upstream end of the drilling being positioned to be covered by said valve guide portion of the bore in the closed position of the valve member, said upstream end of the drilling being progressively uncovered to the bore to permit flow of fuel through the orifice as the valve member moves to the open position.