Fuel injection valve

A method of modifying the sealing system of a fuel injection valve for an engine, the valve being of the type comprising a tubular housing having a central throughway for reciprocably receiving a valve stem, the throughway have an enlarged sealing zone, disposed outwardly of a housing fuel inlet and outlet, the method comprising the steps of:

• forming a housing buffer inlet through the housing intermediate the axial extremities of the sealing zone;
• emplacing a first annular housing seal means in the sealing zone inwardly of a downstream end of the housing buffer inlet;
• emplacing a radially-open, circumferentially-clear, annular spacer in the sealing zone outwardly of the first housing seal means in alignment with the downstream end of the housing buffer inlet;
• emplacing a second annular housing seal means in the sealing zone outwardly of the spacer and of the downstream end of the housing buffer inlet;
• wherein the valve is of the type further comprising a tubular cage coaxially removably receiving at least a portion of the housing and having a cage fuel inlet disposed inwardly of the sealing zone of the housing throughway, the method further comprising
• forming a cage buffer inlet in the cage communicating with the housing buffer inlet and with an annular locus between the housing and the cage, outwardly of the fuel cage inlet, whereby a single source of buffer gas can communicate with the sealing zone of the housing throughway and with said locus;
• and emplacing first and second cage seal means in said locus on opposite axial sides of a mouth of the cage buffer inlet.

A method of sealing a fuel injection valve injecting gaseous fuel into an engine, wherein the valve is of the type comprising a tubular housing having an outer housing fuel inlet, an inner housing fuel outlet defined by a valve seat, and a flowway between the housing fuel inlet and the seat, and a valve stem reciprocably mounted in the housing, at least partially in the flowway, and carrying a valve element for cooperation with the seat, the method comprising:

• mechanically sealing between the interior of the housing and the exterior of the valve stem in two axially spaced housing seal locations both outwardly of the housing fuel inlet;
• injecting an inert, nonflammable gas between the valve stem and the housing, and between the two housing seal locations at a pressure greater than the fuel pressure;
• wherein the valve is of the type further comprising a cage at least partially surrounding the housing and having a cage fuel inlet, the method further comprising
• mechanically sealing between coaxially surrounding and receiving portions of the cage and housing in two axially spaced cage seal locations both outwardly of the cage fuel inlet, and injecting such buffer gas between the housing and cage, and between the two cage seal locations, at such greater pressure;
• wherein the buffer gas is so injected between the housing and cage and between the housing and valve stem through a single cage buffer inlet.