Patent ID: 7866575

Claim:
A fuel injector comprising: a housing defining a high pressure region, a low pressure region, a longitudinal bore, and a valve seat including a valve seat surface and an aperture, the valve seat surface being in fluid communication with the low pressure region and the aperture extending through the valve seat surface and being in communication with the high pressure region; an actuation member disposed within the longitudinal bore for axial displacement therein and including a first axial end surface; and a valve mechanism axially displaceable between first and second positions, the valve mechanism abutting the valve seat in the first position to seal the aperture from communication with the low pressure region, the valve mechanism being displaced from the valve seat in the second position to provide communication between the low and high pressure regions through the aperture, the valve mechanism including a second axial end surface abutting the first axial end surface of the actuation member, the first and second axial end surfaces defining an outer contact perimeter and a chamber within the outer contact perimeter, a radial surface area of the chamber formed by the first and second axial end surfaces being at least 25 percent of a radial surface area defined within the outer contact perimeter.