Fuel injector including valve needle, injection control valve, and drain valve

A fuel injector comprising a valve needle slidable within a bore, a surface associated with said valve needle defining, in part, a control chamber which communicates, through a restriction, with a supply passage, an injection control valve controlling communication between said control chamber and a low pressure reservoir, and a drain valve controlling communication between said supply passage and said low pressure reservoir, wherein said injection control valve and said drain valve include respective armatures movable under the influence of a common electromagnetic actuator comprising a single winding or respective windings associated with the injection control valve and the drain valve respectively, said injection control valve being arranged such that, in use, said injection control valve opens upon de-energization of the single or the respective winding to allow fuel pressure within said control chamber to fall, thereby allowing injection to commence.

A fuel injector comprising a valve needle slidable within a bore, a surface associated with said valve needle defining, in part, a control chamber which communicates, through a restriction, with a supply passage, an injection control valve controlling communication between said control chamber and a low pressure reservoir, and a drain valve controlling communication between said supply passage and said low pressure reservoir, wherein said injection control valve and said drain valve include respective armatures moveable under the influence of a common electromagnetic actuator, said actuator including separate windings which are engergizable independently to cause movement of said armatures and wherein said injection control valve is arranged such that, in use, said injection control valve opens upon partial deengergization of the respective winding to allow fuel pressure within said control chamber to fall, thereby allowing injection to commence.