Patent ID: 7735473
Filing Date: 2010-06-15
Classification: F02M,F16L

Abstract:
1. A connection head structure of a high pressure fuel injection tube comprising, on a connection end portion of a thick-walled thin-diameter steel tube, a spherical seat face, an annular flange formed at an interval from the seat face in a tube axial direction, and a conical surface having a substantially spherical face which tapers toward a tip and continuously extends from the seat face to the annular flange or to a proximity of the annular flange, and a fastening nut is assembled to engage directly or indirectly with a back face of the annular flange, wherein when the thick-walled thin-diameter steel tube has wall thickness t/outer diameter D<0.3, a tube axial direction distance L a spherical body radius R of the seat face is from 0.45 D to 0.65 D, and an outer diameter D wherein an inner circumferential face of the connection head comprises a two-stage tapered face having a cross sectional outline in a tube axial direction of the steel tube that broadens toward an aperture of the tube.