Fuel injector

A fuel injector for use in a fuel system for an internal combustion engine, the fuel injector comprising:

• a supply means for providing a high pressure fuel;
• an injection nozzle including a valve needle which is engageable with a valve needle seating to control fuel delivery from the injector, a surface associated with the valve needle being exposed to fuel pressure within a control chamber;
• a first filling flow path providing flow from the supply means into the control chamber;
• and a control valve for controlling fuel pressure within the control chamber wherein the control valve comprises a valve housing that defines, in part, a first valve chamber and a second valve chamber, and a control valve member slidable within a guide bore of the valve housing and operable between:
• (i) a first state in which the first valve chamber communicates with the supply means, and in which flow between the second valve chamber and a low-pressure drain is prevented;
• and (ii) a second state in which flow between the first valve chamber and the supply means is prevented, and in which the second valve chamber is in communication with the low-pressure drain;
• and wherein the fuel injector further comprises:
• a drain flow path including a drain restriction and permitting flow from the control chamber to the second valve chamber when the control valve member is in the second state, and a second filling flow path permitting flow from the first valve chamber into the control chamber when the control valve member is in the first state, wherein the second filling flow path bypasses the drain restriction;
• wherein the drain flow path and the second filling flow path are formed within the valve housing.