Fuel injector for IC engine - has orifice area varied to keep discharge pressure independent of quantity injected

摘要

The injector has a needle (2) moving in a body (1). The needle has a tapered section (5) below which there is a dowel (6). Fuel pressure on the taper lifts the needle off the seat (7) and permits fuel to flow through a space (15) below the seat and bores (14,13) in the dowel to a discharge chamber (12). The dowel uncovers longitudinal slots (11) from the discharge chamber. The area of flow is determined by the extent to which the dowel rises over the slots. This depends on the quantity injected and is independent of the pressure which is kept constant by the spring load on the needle.