Patent ID: 7694891
Filing Date: 2010-04-13
Classification: F02M

Abstract:
1. A method of operating an intensifier type fuel injector with direct needle control comprising: providing a boost piston and a drive piston, each disposed to controllably force a needle toward a needle closed position in response to hydraulic forces thereon, the boost piston including a stop to stop the motion of the boost piston before the needle reaches the closed position; when the needle is to be closed, unbalancing the hydraulic forces on the boost piston and drive piston to controllably force the needle toward the needle closed position, the area of the drive piston being adequate to maintain the needle closed against a needle opening force of fuel at an intensified pressure around the needle; when the needle is to be opened for fuel injection, equalizing the hydraulic forces of the boost and drive pistons to allow the needle to open.