| 摘要 |
<p>A connection head structure of a high pressure fuel injection tube is provided to avoid an interference between an annular flange and an opposing part by sufficiently maintaining an tube axial direction length of the connection head and to obtain a good sealability to prevent leaking during autofrettage processing with a high pressure of not less than 300 MPa. A connection head structure of a high pressure fuel injection tube includes, on a connection end portion of a thick walled fine steel tube, a spherical seat face, an annular flange, and a circular conic face that continuously extends from the seat face, wherein a washer and a fastening nut are assembled, characterized in that when a thick walled fine steel tube has t (wall thickness) / D (outer diameter) < 0.3, an tube axial direction distance L1 from a connection head end to the back face of the annular flange is from 0.38D to 0.7D, a spherical body radius R of the seat face is from 0.45D to 0.65D, and an outer diameter D 1 of the annular flange is from 1.2D to 1.4D, wherein an inner circumferential face of the connection head includes a two stage tapered face having a cross section outline in a tube axial direction of the steel tube that broadens toward the aperture of the tube.</p> |
