COMMON RAIL FOR DIESEL ENGINE

摘要

PURPOSE: A common rail is provided which is equipped with a heightened internal pressure fatigue strength by lessening the difference in the hardness or elongation between the rail inner surface or facial layer of a non-metal inclusion and the steel skin surface and lessening the degree of fatigue stress concentration. CONSTITUTION: The common rail for Diesel engine is configured so that the peripheral wall in axial direction of a main pipe rail having a flow passage in the axal direction is furnished with a branch hole leading to the flow passage and a branch connector is connected with the branch hole through a joint member provided in a single piece with or separately from the main pipe rail, wherein a fatigue strength reinforcing layer subjected to a diffusion process by heating of a pre-plated Ni-layer is produced on the common rail inside surface at least in its part. Thereby the strength of the fatigue strength reinforcing layer of Ni is heightened and accordingly the degree of the fatigue stress concentration is lowered to result in enhancement of the internal pressure fatigue strength, and the resultant common rail is equipped with excellent durability, is free of fuel leakage due to cracking, and can exert a stabilized function certainly.