| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a connection head structure of a high-pressure fuel injection tube capable of avoiding the interference between an annular flange and an opposing part by sufficiently maintaining the length of the connection head in the axial direction and of providing a high sealability to prevent leakage during autofrettage processing with a high pressure of not less than 300 MPa. <P>SOLUTION: This connection head structure of a high-pressure fuel injection tube comprises, at the connection end of a thick-walled small-diameter steel tube, a spherical seat surface, an annular flange part, and a conical surface arranged continuously with the seat surface, and has a washer and a fastening nut assembled therein. When the thick-walled small-diameter steel tube has t (wall thickness)/D (outer diameter) <0.3, an axial distance L1 from the end of the connection head to the rear surface of the annular flange part is 0.38D to 0.7D, the spherical body radius R of the seat surface is 0.45D to 0.65D, and the outer diameter D1 of the annular flange part is 1.2D to 1.4D. The inner peripheral surface of the head part is the connection head having such a two-stage tapered surface that the profile of the cross section of the steel tube in the tube axial direction expands toward the opening. <P>COPYRIGHT: (C)2009,JPO&INPIT |
