| 摘要 |
[PROBLEMS] A fuel injection pipe for high pressure, having a bent section, in which fuel injection pipe a fatigue fracture in the bent section can be prevented as much as possible and which is used for a common rail system. A technique for bending the pipe is also provided. [MEANS FOR SOLVING PROBLEMS] In the fuel injection pipe for high pressure, a wall-thickness/outer-diameter ratio of the pipe is not more than 0.3, the pipe has at least one bent (R) portion whose radius of bending is not more than 2.7 times the outer diameter of the pipe, and an inner radius flattening ratio of the bent portion is not more than 9%. The method of bending the pipe is performed as follows: that portion of a narrow diameter metal pipe which corresponds to a portion to be bent is flattened with the pipe held by a bending jig, and the pipe is bent with the pipe flattened. |
