Patent ID: 7028918

Claim:
A closed nozzle fuel injector with improved cooling, said fuel injector being sized to be received in an injector bore of a cylinder head of an internal combustion engine, said fuel injector comprising: a substantially tubular retainer having a proximal end with a nozzle support portion, said nozzle support portion having an outer peripheral surface and an engagement opening with an inner peripheral surface; and a nozzle housing received within said retainer at said proximal end, said nozzle housing including an integral nozzle shank with an outer peripheral surface and a longitudinal axis, said integral nozzle shank having an elongated shape in which a longitudinal axial dimension of said integral nozzle shank along said longitudinal axis is larger than a diameter of said outer peripheral surface of said integral nozzle shank, said integral nozzle shank further having an elongated valve cavity adapted to receive a valve element therein, and a plurality of injection holes at a tip of the nozzle shank which are adapted to spray fuel when said valve element is moved within said elongated valve cavity, said valve element contacting said integral nozzle shank to prevent flow to said at least one injection hole when said valve element is closed in said elongated valve cavity; wherein said integral nozzle shank and said nozzle support portion define an annular portion of said engagement opening between said integral nozzle shank and said nozzle support portion, and said inner peripheral surface of said nozzle support portion has a diameter adjacent to said tip that is smaller than said diameter of said outer peripheral surface of said integral nozzle shank adjacent to said tip in a manner that an interference fit exists at a seal interface between said integral nozzle shank and said nozzle support portion, said seal interface being positioned adjacent to said tip of the nozzle shank when said integral nozzle shank is installed in said nozzle support portion to prevent combustion gas from passing through said seal interface and entering said annular portion of said engagement opening between said integral nozzle shank and said nozzle support portion, said retainer engaging an outer barrel, and having a longitudinal axial dimension along said longitudinal axis of said nozzle housing that is larger than said longitudinal axial dimension of said integral nozzle shank.