Usui Kokusai Sangyo Kaisha Limited

Nobuo Kato

Tadahiro Uematsu

Toshiyuki Omura

Mitsumasa Otaka

Shoichiro Usui

Koichi Hayashi

Munekatsu Furugen

Shigeyuki Ishida

High pressure fuel injection pipe

A thick-wall small-diameter high-pressure fuel injection pipe has a spherical seat surface, an annular flange, and a conical surface continued from the seat surface at a connecting end of the pipe. If the pipe is configured so that t (thickness)/D (outer diameter)&#x3c;0.3, then an axial distance from the connecting head end to the back face of the annular flange is 0.38D to 0.6D, a spherical radius of the seat surface is 0.45D to 0.65D, the annular flange 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. If the pipe is configured so that t (thickness)/D (outer diameter)&#x2267;0.3, then the axial distance from the connecting head end to the back face of the annular flange is 0.38D to 0.7D.

Connecting head structure for high-pressure fuel injection pipes

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)&#x3c;0.3, an tube axial direction distance Lfrom a connection head end to the back face of the annular flange is from 0.38 D to 0.7 D, a spherical body radius R of the seat face is from 0.45 D to 0.65 D, and an outer diameter Dof the annular flange is from 1.2 D to 1.4 D, 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.

Connection head structure of high pressure fuel injection tube

A high-pressure fuel injection pipe has a connecting head portion increased in diameter by buckling molding at the end of a thick and small-diameter metallic pipe. An under-head portion of the connecting head is formed with a thick wall portion that satisfies conditions of: a radius of curvature Rof a portion A of the thick wall portion continuing to the connecting head is 0.03 to 0.15 times the outer diameter of the pipe; a radius of curvature Rof a portion B continuing from the portion A of the thick wall portion to a straight pipe portion is 0.3 to 1.5 times the outer diameter of the pipe; and a maximum diametrical size w of the thick wall portion is 0.25 to 0.4 times a maximum diametrical projecting length W of the connecting head.

High-pressure fuel injection pipe

A high-pressure fuel injection pipe having connecting head portion is provided which is capable of eliminating a fear of the occurrence of cavitation erosion of the inner surface of the connecting head portion and a fatigue failure of the same head portion by having a contour of a cross section of an annular pocket occurring in an inner part of the connecting head portion during a head portion processing operation extend shallowly and gently. This fuel injection pipe has at a connecting end portion of a thick-walled steel pipe having a relatively small diameter, including a seat surface, an annular flange formed so that the flange is axially spaced from the seat surface, and a conical surface connected to the seat surface, extending therefrom to the annular flange and tapering off to a free end of the connecting head portion, wherein the conical surface is provided at a part thereof with an annular, shallow, cross-sectionally curved recess.

High-pressure fuel injection pipe having connecting head portion

A high-pressure fuel injection pipe of doubled type, comprising: a thick outer tube; and an inner tube of made a metal and fitted in the outer tube to form a doubled pipe which is formed at its end portion with a connecting head having a face to be fitted on a seat of a mating partner. The outer tube is made of stainless steel or titanium, and the inner tube is formed of a thin metal having a high corrosion-resistance and a high strength and is doubled on the inner circumference of the outer tube throughout its entire length.

The invention is to provide a high pressure fuel injection pipe for a diesel engine wherein a fuel, leaked from a seat port is discharged to the outside of a head cover without leaking into the head cover so that a leakage of fuel can be promptly detected and is directed to the high pressure fuel injection pipe formed by abutting and engaging a pressure portion formed on a connecting head of a fuel injection pipe body to a pressure receiving seat portion of a counterpart member so as to provide a firm connection of the fuel injection pipe body to the counterpart member by screwing a fastening nut to press the connecting head to the counterpart member, wherein an annular washer having at least one groove or through hole formed in a radial direction on the circumference of the washer and a seal member is disposed in the vicinity of an outer end portion of a threaded engagement potion defined between the fastening nut and the counterpart member so that a fuel leaked into the inside of the fastening nut from a seat portion defined between the pressure seat portion formed on the connecting head and the pressure receiving seat of the counterpart member may be discharged to the outside through the groove or through hole. Alternatively, the leaked fuel may be discharged to the outside through a through hole which is formed on the fastening nut.

High pressure fuel injection pipe for diesel engine

A high-pressure fuel injection pipe for a diesel engine includes a fuel pipe main body with opposed first and second ends. First and second fastening nuts are mounted over the first and second ends. A first unitary outer pipe is mounted over a portion of the fuel pipe main body and is mounted to the first fastening nut. A second unitary outer pipe is mounted over a portion of the fuel pipe main body and has an end mounted to the second fastening nut. The end of the second outer pipe is spaced from the second fastening nut is expanded circumferentially and telescoped over a portion of the first outer pipe. A sealing ring is sealingly engaged between the first and second outer pipes.

High-pressure fuel injection pipe for diesel engine

A structurally simple common rail is highly sealed and light weight manner. The common rail includes a thick wall pipe having a flow passage for accumulating pressure of high pressure fuel. The high pressure fuel is supplied from a high-pressure pump and distributed to an injection nozzle. The end portion of the thick wall pipe is reduced in diameter by drawing. A thread portion is formed on an outer peripheral surface of the diameter-reduced end portion. A connecting end of a piping component is connected to the end portion of the thick wall pipe by screwing a nut to the thread portion of the thick wall pipe.

Common rail and method of manufacturing same

A common rail is provided which is simple in structure and capable of connecting a piping component to a thick wall pipe thereof in a highly sealed and light weighted manner. In a common rail adapted to connect a pipe component to at least one end of a thick wall pipe having a flow passage 1' therein for accumulating pressure of high pressure fuel so that high pressure fuel is supplied from a high-pressure pump and distribute-supplied to an injection nozzle, the end portion of the thick wall pipe 1 is reduced in diameter by drawing. A thread portion 1a is formed in an outer peripheral surface of the diameter-reduced end portion. A connecting end of the piping component 3 is connected to an end portion of the thick wall pipe 1 by screwing a fastening screw means 5, 5' to the thread portion 1a.

A joint structure for joining a branch member to a high pressure fuel rail which automatically aligns a spigot head of the branch member, if offset, upon tightening of a bolt and increases the rigidity of the spigot head to provide a sufficient degree of mechanical strength so that the spigot head can positively be 'seated', and which insures connection between the branch member and the fuel rail if a fuel under substantially high pressure repeatedly flows over a prolonged period of time and if piping is subject to vibration and is free from leakage. In this joint structure, the branch member includes a spherical spigot end surface at its distal end, an annular flange axially spaced away from the spigot end surface, and a conical surface converging from the annular flange toward the spigot end surface.

Growing community of inventors

Susono, Japan

Nobuo Kato