Low pressure sealing arrangement for a fuel injector

Abstract

A low pressure sealing arrangement for a fuel injector which includes a housing containing a cylindrical barrel having a bore formed therein. Within the bore is positioned an axially movable plunger and piston which form a timing chamber therebetween. An inner surface of the housing cooperates with an outer surface of the barrel to form an annular cavity and a passage connects one end of the annular cavity with the timing chamber. Located within the annular cavity itself is arranged a pressure activated valve which is surrounded by a cylindrical sleeve. The pressure activated valve is spring biased to a closed position and is movable between an open and a closed position to regulate the flow of fluid into the timing chamber. The outer surface of the pressure activated valve cooperates with the inner surface of a cylindrical sleeve to form a first low pressure seal therewith when the valve is in the closed position. In addition, an O-ring positioned at one end of the cylindrical sleeve abuts against a top surface of the annular cavity to form a second low pressure seal when the pressure activated valve is in the closed position. The two low pressure seals prevent leakage of fluid from the timing chamber while permitting rapid reciprocation of the pressure activated valve without exerting an excessive amount of drag thereon.