Patent ID: 7516906

Claim:
A fuel injector for use in an internal combustion engine, the fuel injector comprising: a valve needle which is movable within a nozzle body and engageable with a valve needle seat to control fuel injection through an injector outlet, wherein a valve needle chamber for receiving fuel is defined at an end of the valve needle; an actuator arranged within an actuator housing so as to control fuel pressure within a control chamber, a surface associated with the valve needle being exposed to fuel pressure within the control chamber; a fuel delivery path for delivering fuel to the injector outlet when the valve needle is lifted from the valve needle seat, the valve needle seat being provided with a communication path between the fuel delivery path and the valve needle chamber to aid opening movement of the valve needle; and a load transmitter for transmitting movement of the actuator to the valve needle, wherein the load transmitter includes a bellows arrangement which is compressible and expandable in response to said actuator movement so as to vary fuel pressure within the control chamber and control movement of the valve needle relative to the valve needle seat; wherein one end of the nozzle body is received within the actuator housing so that a lower end of the nozzle body projects therefrom and wherein the nozzle body defines an external seating surface for abutment with an internal abutment surface of the actuator housing; wherein the communication path is provided with a damper valve arranged to define a restricted flow path between the axial flow path and the valve needle chamber; and wherein the damper valve includes a damper valve member which is engageable with a seating, wherein the damper valve member has (i) a seated position in circumstances in which the valve needle is lifting away from the valve needle seat so that fuel flows between the chamber and the communication path through the restricted flow path, thereby to damp opening movement of the valve needle, and (ii) a lifted position in circumstances in which the valve needle is moving towards the valve needle seat so that fuel flow can by-pass said restricted flow path, thereby to ensure closing movement of the valve needle is substantially undamped.