Dual port unit pump injector, and engine efficiency methods

摘要

A unit pump (10) is provided with a bleed port (12) spaced from the main injection port (14). The bleed port (12) improves the rate shape of injection through an associated fuel injector by slowing the initial rate of injection. The bleed port (12) permits shifting of the engine speed at which speed advance occurs. The bleed port (12) also flattens the fuel backup curve. Altering the cross section flow area (18) of the bleed port, axial spacing between the bleed port and inlet port (20) permit the designer to vary (or even eliminate) the impact of the bleed port (12) on the unit pump (10) performance.