| 摘要 |
<p>A high-pressure fuel injection pipe is provided which prevents generation of a crack in a pocket portion in molding of a head, generation of a crack due to cavitation erosion and generation of a tensile stress involved with formation of a pocket and is resistant against fatigue breakdown. In a high-pressure fuel injection pipe, comprising a spherical seat surface, an annular flange portion, and a conical surface continued from the seat surface at a connecting end of a thick-wall small-diameter steel pipe and incorporating a washer and a tightening nut, in the case of a pipe material with t (thickness) / D (outer diameter) < 0.3, a connecting end is provided that an axial distance from the connecting head end to the annular flange portion back face is 0.38D to 0.6D, a spherical radius of the seat surface is 0.45D to 0.65D, and the annular flange portion outer diameter is 1.2D to 1.4D, and an inner peripheral surface of the head has a substantially flat cylindrical surface or a conical surface, while in the case of a pipe material with t (thickness) / D (outer diameter) ‰¥ 0.3, the axial distance from the connecting head end to the annular flange portion back face is 0.38D to 0.7D.</p> |
