Fuel injector

摘要

This disclosure relates to a unit-type fuel injector for an internal combustion engine such as a reciprocating piston internal combustion engine. The injector includes an injector body forming a plunger bore, and a plunger that reciprocates in the bore. A fuel supply passage and a drain passage are formed in the body, and a fuel injection chamber is formed at the lower end of the plunger bore. A feed hole connects the chamber with the supply passage, and a scavenge passage connects the supply and drain passages. During a retracted plunger, or fuel metering, portion of the injector cycle, the plunger opens the feed hole and closes the scavenge passage, and during a down plunger, or scavenging, portion of the injector cycle, the plunger closes the feed hole and opens the scavenge passage. An annular groove is formed between injector parts and surrounds the chamber, and the groove collects leakage. A restricted bleed hole connects the groove with the low pressure drain and removes the leakage. The feed hole is at an end of the supply passage, and the incoming fuel flows in a direct path through the supply passage and feed hole to the injection chamber.