Fuel injection nozzle for air-compressing, self-igniting reciprocating

Abstract

A fuel injection nozzle for air-compressing, self-igniting reciprocating internal combustion engines, particularly for such engines arranged for a direct injection of fuel, comprises an axially slidable and axially guided, spring-biased valve needle for closing the nozzle orifices in the nozzle tip. Fuel is supplied to an annular chamber through a transverse bore and an axial bore of the valve needle to a plenum chamber, which is defined by the valve seat cooperating with the valve needle. Between the plenum chamber and the means for guiding the valve needle, the outside peripheral surface of the latter is surrounded by a clearance space, which is adapted to be flushed with fuel. In order to ensure a tight seal between the valve needle and the valve seat and to prevent a discharge of fuel during the closing operation of the valve needle, also to facilitate the flow of fuel through the nozzle orifices and to ensure a cooling action, the valve seat comprises a plurality of annular elevations, which surround respective inlet openings of the nozzle orifices and have inwardly facing surfaces which face and conform to adjacent surface portions of the end portion of the valve needle. The clearance space is directly or indirectly connected to the annular chamber regardless of the position of the valve needle.