Patent ID: 8602319

Claim:
A fuel injector comprising: an injector body with a tip component that defines at least one nozzle outlet, and having disposed therein a needle control chamber separated from a nozzle chamber by a frustoconical bore that tapers inward in a direction of the tip component; a needle valve member positioned in the injector body and including an opening hydraulic surface exposed to fluid pressure in the nozzle chamber and a closing hydraulic surface exposed to fluid pressure in the needle control chamber, and being movable between a first position at which the nozzle outlet is blocked from the nozzle chamber, and a second position at which the nozzle outlet is open to the nozzle chamber; a frustoconical segment of the needle valve member being positioned in the frustoconical bore and having a narrowing taper in a direction of the tip component; and the frustoconical bore has a length greater than a large end diameter.