Patent ID: 7690587
Filing Date: 2010-04-06
Classification: F02M

Abstract:
1. A fuel injector for use in an internal combustion engine, the fuel injector comprising: an inlet region for passing fuel to an accumulator volume, a valve needle, a valve needle seat, a control chamber, an actuator arrangement, an injector outlet, and damping means comprising a damper chamber for damping an opening movement of the valve needle; the actuator arrangement comprising a sleeve member defining a bore having a longitudinal axis and defining a radially extending wall member fixedly coupled to the sleeve and further defining the bore, the sleeve member and wall member retracting longitudinally in response to a de-energisation of the actuator arrangement and causing the valve needle to move away from the valve seat; the injector further comprising a piston member in communication with the valve needle, the piston member and wall member arranged to form a slidable fluid tight seal between the piston and the wall member within the bore, the control chamber being defined on one side of the fluid tight seal and the damper chamber being defined on the other side of the fluid tight seal; the valve needle being engageable with the valve needle seat to control fuel injection through the injector outlet; the actuator arrangement being arranged to control fuel pressure within the control chamber, a surface associated with the valve needle being exposed to fuel pressure within the control chamber such that fuel pressure variations within the control chamber control movement of the valve needle relative to the valve needle seat; the damper chamber being in fluid communication with the accumulator volume via damping orifices, the damping means being arranged such that fuel pressure variations within the damper chamber damp the opening movement of the valve needle; wherein the damping means is arranged such that as the opening movement of the valve needle occurs, whereby the valve needle lifts from its valve needle seat, there is a flow of fuel into the damper chamber only through the damping orifices, and as a closing movement of the valve needle occurs, there is a flow of fuel out of the damper chamber through the damping orifices and a vent passage such that in use there is a through flow of fuel through the damper chamber.