Fuel injector with a restricted flow means in the control valve arrangement

摘要

A fuel injector including a control valve arrangement for use in controlling fuel pressure within a control chamber (30) comprises a control valve member (32) which is movable between a first position in which the control chamber (30) communicates with a source of high pressure fuel and a second position in which the control chamber (30) communicates with a low pressure fuel drain and communication between the control chamber (30) and the source of high pressure fuel is broken. The control valve arrangement includes restricted flow means (48) for restricting the rate of flow of fuel from the source of high pressure fuel to the control chamber (30) when the control valve member is moved towards its first position. The provision of the restricted flow means (48) prevents unbalanced hydraulic forces acting on the control valve member when the control valve member is moved towards its first position, which can otherwise lead to valve needle dither between injecting and non-injecting states.