Liquid fuel injection systems

Claim 1

A liquid fuel injection nozzle of the kind comprising a nozzle body, a bore formed in the body, a cylindrical valve member located in the bore, a seating at one end of the bore, the valve member being shaped to co-operate with the seating, a fuel inlet in the body, a passage connecting said inlet with said one end of the bore whereby when fuel under pressure is supplied to said inlet a force will be developed on the valve member acting to move the valve member away from the seating, an outlet from said one end of the bore and through which fuel can flow when the valve member is lifted from the seating, resilient means acting to urge the valve member onto the seating, a piston operably associated with the valve member, a cylinder in which said piston is located, a conduit through which fuel can be supplied to said cylinder at a pressure substantially the same as the pressure of fuel supplied to the inlet, the pressure of fuel in said cylinder acting on said piston to apply a force to said valve member in a direction to maintain the valve member on the seating, the area of the piston exposed to the fuel pressure in the conduit being less than the area of the valve member exposed to the fluid pressure at the inlet, and a non-return valve in said conduit and acting to prevent fuel flow out of said cylinder, the arrangement being such that the force exerted on the valve member and acting to urge the valve member onto the seating varies as the pressure of fuel supplied to the inlet varies.