TIMING PLUNGER ASSEMBLY AND TIMING PLUNGER

摘要

PURPOSE: To prevent sticking of timing plunger means encountered in fuel injector operation and improve its wear and scuff-resistance by forming it from a wear-resisting ceramic material of a specific thermal expansion coefficient and hardness. CONSTITUTION: This timing plunger assembly for use in a unit fuel injector 10 for internal combustion engines is arranged to inject supply fuel into an engine cylinder through reciprocation of a timing plunger 12 placed in an axial bore 20 cut in a body 14 of the unit fuel injector 10. The timing plunger 12 is formed from a wear-resisting ceramic material of a thermal expansion coefficient greater than 6×10<-6> / deg.C and a hardness greater than 800 kg/mm<2> . Preferred ceramic materials are zirconium, alumina-zirconium and alumina.