Fuel injection nozzle

Claim 1

A fuel injection nozzle for supplying fuel to a compression ignition engine comprising an elongated nozzle body defining a blind bore, an annular seating defined at the blind end of the bore, a hollow boss defined at the end of the body remote from the seating, a valve member movable axially within the bore and defining a space with the wall of the bore, the valve member being shaped at one end for engagement with the seating and having its other end projecting from the bore and extending within said boss, a fuel inlet communicating with said space, resilient means biasing the valve member into engagement with the seating, the valve member being movable by fuel pressure away from the seating to allow fuel flow through an outlet orifice extending from the bore downstream of the seating, an inner guide bush surrounding the portion of the valve member within said boss, said inner guide bush serving to guide the movement of the valve member, an outer guide bush in which the inner guide bush is axially slidable, an outwardly extending flange formed on the outer guide bush, said flange overlying an annular end surface of said boss, a washer interposed between said end surface and said flange, means engagable with said boss to clamp the washer and flange to said surface to achieve a fuel tight seal, a clearance defined between an inner surface of said boss and another surface of said outer guide bush, whereby prior to clamping the washer and flange to said surface the outer guide bush can be positioned laterally to achieve alignment of the valve member, cooperating surfaces defined by the valve member and the wall of the bore respectively, said cooperating surfaces forming a restrictor which acts to restrict the flow of fuel between the fuel inlet and the outlet orifice during the initial movement of the valve member away from the seating, said cooperating surfaces separating as the valve member moves to the fully open position to allow substantially unrestricted flow of fuel and a stop to determine the fully open position of the valve member.