Patent ID: 7874502

Claim:
A control valve arrangement for use in controlling fuel pressure within a control chamber of a fuel injector thereby to control the movement of an injector valve needle relative to an injector valve seating wherein, in use, a portion of the injector valve needle is exposed to fuel pressure within the control chamber, the control valve arrangement including: a control valve member that is movable between a first position and a second position, wherein, in the first position, the control valve member engages a first seating such that the control chamber communicates with a source of high pressure fuel and communication between the control chamber and a low pressure fuel drain is prevented thereby urging the injector valve needle against the injector valve needle seating, and wherein in the second position the control valve member engages a second seating such that the control chamber communicates with the low pressure fuel drain and communication between the control chamber and the source of high pressure fuel is broken thereby causing the injector valve needle to lift away from the injector valve needle seating, wherein the second seating is defined by a surface of a bore provided in a valve housing within which the control valve member is movable; and a restricted flow path for: i) restricting the rate of flow of fuel from the control chamber to the low pressure fuel drain when the control valve member is moved from the first position to the second position, thereby reducing the speed at which the injector valve needle lifts from the injector valve needle seating; and ii) restricting the rate of fuel flow from the source of high pressure fuel to the low pressure fuel drain when the control valve member is moved from the second position to the first position to urge the injector valve needle against the injector valve needle seating while reducing the loss of high pressure fuel to low pressure, wherein the restricted flow path comprises a restricted flow passage being located between the first seating and the second seating and defined by an outer surface of the control valve member and the bore in the valve housing.