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A joint structure connects a diverging branch pipe to a fuel rail for an internal combustion engine. The fuel rail is stainless steel or steel with rust prevention processing on at least the inner face. The diverging branch pipe is a double pipe with inner and outer pipes. The inner pipe has excelle

A joint structure connects a diverging branch pipe to a fuel rail for an internal combustion engine. The fuel rail is stainless steel or steel with rust prevention processing on at least the inner face. The diverging branch pipe is a double pipe with inner and outer pipes. The inner pipe has excellent rust preventing ability with respect to fuel on its inner face in comparison with the outer face of the outer pipe. The inner and outer pipes are connected by a nut for fastening through a joint fitting. A connecting seal portion of the diverging branch pipe and the joint fitting has rust preventing ability equal to that of the inner circumferential face of the diverging branch pipe. An entire liquid contact portion, including a seal face of the diverging branch pipe with respect to the fuel is covered with the inner pipe.

대표청구항 ▼

What is claimed is: 1. A joint structure of a diverging branch pipe in a fuel rail for an internal combustion engine in which the fuel rail for an internal combustion engine manufactured by stainless steel or manufactured by steel performed with respect to rust prevention processing on at least the

What is claimed is: 1. A joint structure of a diverging branch pipe in a fuel rail for an internal combustion engine in which the fuel rail for an internal combustion engine manufactured by stainless steel or manufactured by steel performed with respect to rust prevention processing on at least the inner face, and the diverging branch pipe constructed by a double pipe formed by an outer pipe and an inner pipe having excellent rust preventing ability with respect to fuel on its inner circumferential face in comparison with the outer circumferential face of the outer pipe are connected by a nut for fastening through a joint fitting; wherein a connecting seal portion of said diverging branch pipe and the joint fitting has rust preventing ability equal to that of the inner circumferential face of the diverging branch pipe; an entire liquid contact portion including a seal face of the diverging branch pipe with respect to the fuel is covered with said inner pipe; and a pressure receiving portion of the inner pipe including the seal face is constructed so as to be supported by said outer pipe. 2. The joint structure of the diverging branch pipe in the fuel rail for an internal combustion engine according to claim 1, wherein a gasket is interposed between the connecting seal portion of said joint fitting and a seat face of the diverging branch pipe, and the connecting construction is set by said nut for fastening assembled into this diverging branch pipe in advance. 3. The joint structure of the diverging branch pipe in the fuel rail for an internal combustion engine according to claim 1, wherein a spool or a projection is arranged at the terminal of said diverging branch pipe, and is set to the pressure receiving portion of the nut for fastening. 4. The joint structure of the diverging branch pipe in the fuel rail for an internal combustion engine according to claim 2, wherein a spool or a projection is arranged at the terminal of said diverging branch pipe, and is set to the pressure receiving portion of the nut for fastening. 5. A joint structure of a diverging branch pipe in a fuel rail for an internal combustion engine manufactured by stainless steel or manufactured by steel performed with respect to rust prevention processing on at least the inner face, and the diverging branch pipe constructed by a double pipe formed by an outer pipe and an inner pipe having excellent rust preventing ability with respect to fuel on its inner circumferential face in comparison with the outer circumferential face of the outer pipe are connected by a nut for fastening through a joint fitting; wherein a connecting seal portion of said diverging branch pipe and the joint fitting has rust preventing ability equal to that of the inner circumferential face of the diverging branch pipe; an entire liquid contact portion including a seal face of the diverging branch pipe with respect to the fuel is covered with said inner pipe; and a pressure receiving portion of the inner pipe including the seal face is constructed so as to be supported by said outer pipe, wherein the connection seal portion of said joint fitting is formed in a concave sectional shape having a flat face perpendicular to the axis of a branching hole of the joint fitting, and an opening end face of said outer pipe is bent so as to be covered with an opening end portion of said inner pipe, and the diverging branch pipe formed so as to set the inner circumferential face of the inner pipe to a seat face is connected by the nut for fastening assembled into this diverging branch pipe in advance. 6. The joint structure of the diverging branch pipe in the fuel rail for an internal combustion engine according to claim 5, wherein a gasket is interposed between the connecting seal portion of said joint fitting and a seat face of the diverging branch pipe, and the connecting construction is set by said nut for fastening assembled into this diverging branch pipe in advance. 7. The joint structure of the diverging branch pipe in the fuel rail for an internal combustion engine according to claim 5, wherein a spool or a projection is arranged at the terminal of said diverging branch pipe, and is set to the pressure receiving portion of the nut for fastening. 8. A joint structure of the diverging branch pipe in the fuel rail for an internal combustion engine in which the fuel rail for an internal combustion engine manufactured by stainless steel or manufactured by steel performed with respect to rust prevention processing on at least the inner face, and the diverging branch pipe constructed by a double pipe formed by an outer pipe and an inner pipe having excellent rust preventing ability with respect to fuel on its inner circumferential face in comparison with the outer circumferential face of the outer pipe are connected by a nut for fastening through a joint fitting; wherein a connecting seal portion of said diverging branch pipe and the joint fitting has rust preventing ability equal to that of the inner circumferential face of the diverging branch pipe; an entire liquid contact portion including a seal face of the diverging branch pipe with respect to the fuel is covered with said inner pipe; and a pressure receiving portion of the inner pipe including the seal face is constructed so as to be supported by said outer pipe, wherein the connecting seal portion of said joint fitting is formed in a conical convex shape, and a seat face of said diverging branch pipe is formed in a single flare shape, and a conical gasket of a ring shape is interposed between the connecting seal portion of the conical convex shape and the seat face of the single flare shape, and the connecting construction is performed by the nut for fastening assembled into the diverging branch pipe in advance. 9. A joint structure of the diverging branch pipe in the fuel rail for an internal combustion engine in which the fuel rail for an internal combustion engine manufactured by stainless steel or manufactured by steel performed with respect to rust prevention processing on at least the inner face, and the diverging branch pipe constructed by a double pipe formed by an outer pipe and an inner pipe having excellent rust preventing ability with respect to fuel on its inner circumferential face in comparison with the outer circumferential face of the outer pipe are connected by a nut for fastening through a joint fitting; wherein a connecting seal portion of said diverging branch pipe and the joint fitting has rust preventing ability equal to that of the inner circumferential face of the diverging branch pipe; an entire liquid contact portion including a seal face of the diverging branch pipe with respect to the fuel is covered with said inner pipe; and a pressure receiving portion of the inner pipe including the seal face is constructed so as to be supported by said outer pipe, wherein the connecting seal portion of said joint fitting is formed in a conical concave shape, and a seat face of said diverging branch pipe is formed in a single flare shape, and a conical gasket of an abacus ball shape is interposed between the connecting seal portion of said conical concave shape and the seat face of said single flare shape, and the connecting construction is performed by the nut for fastening assembled into the diverging branch pipe in advance. 10. A joint structure of the diverging branch pipe in the fuel rail for an internal combustion engine in which the fuel rail for an internal combustion engine manufactured by stainless steel or manufactured by steel performed with respect to rust prevention processing on at least the inner face, and the diverging branch pipe constructed by a double pipe formed by an outer pipe and an inner pipe having excellent rust preventing ability with respect to fuel on its inner circumferential face in comparison with the outer circumferential face of the outer pipe are connected by a nut for fastening through a joint filling; wherein a connecting seal portion of said diverging branch pipe and the joint filling has rust preventing ability equal to that of the inner circumferential face of the diverging branch pipe; an entire liquid contact portion including a seal face of the diverging branch pipe with respect to the fuel is covered with said inner pipe; and a pressure receiving portion of the inner pipe including the seal face is constructed so as to be supported by said outer pipe, wherein a taper face of a concave shape having an inclination angle α with respect to the axis of a branching hole is formed in the connecting seal portion of said joint filling; a connecting head portion of the outer pipe of said diverging branch pipe is formed in a shape having a taper wall of a convex shape having an inclination angle α짹5째 correspondingly to the taper face of the concave shape having the inclination angle c in the connecting seal portion of said joint filling; a seat face of a ring shape is formed by bending the tip of the inner pipe outside so as to cover the connecting head portion of the outer pipe having the taper wall of the convex shape; a conical gasket approximately formed in a ring shape is interposed between this seat face and the taper face of said joint fitting; and the connecting construction is performed by the nut for fastening assembled into said diverging branch pipe in advance. 11. The joint structure of the diverging branch pipe in the fuel rail for an internal combustion engine according to claim 10, wherein said inclination angle α is set to 50째 to 120째 with respect to the axis of the branching hole of the joint fitting. 12. The joint structure of the diverging branch pipe in the fuel rail for an internal combustion engine according to claim 10, wherein the tip shape of the connecting head portion of said diverging branch pipe is formed approximately perpendicularly to the axis of the diverging branch pipe, and the seat face of the inner pipe covering the connecting head portion is formed on the taper wall face of a turning-up double structure. 13. A joint structure of a diverging branch pipe in a fuel rail for an internal combustion engine in which the fuel rail for an internal combustion engine manufactured by stainless steel or manufactured by steel performed with respect to rust prevention processing on at least the inner face, and the diverging branch pipe constructed by a double pipe formed by an outer pipe and an inner pipe having excellent rust preventing ability with respect to fuel on its inner circumferential face in comparison with the outer circumferential face of the outer pipe are connected by a nut for fastening through a joint fitting; wherein a connecting seal portion of said joint fitting is set to a flat face; a diameter enlarging portion is arranged in a terminal portion of said diverging branch pipe and a pressure receiving portion is formed on the outer circumferential face of this diameter enlarging portion; a gasket is interposed between a seat face formed on an end face of a connecting head portion connected to this pressure receiving portion and the flat face of said joint fitting; a pressing seating face portion formed in a washer assembled onto the diverging branch pipe side in advance is abutted and engaged with the pressure receiving portion formed on the outer circumferential face of the diameter enlarging portion of said diverging branch pipe; an entire liquid contact portion of the inner circumferential face of the diverging branch pipe with respect to the fuel and the seat face is covered with said inner pipe; and the connecting construction is performed by the nut for fastening. 14. A joint structure of a diverging branch pipe in a fuel rail for an internal combustion engine in which the fuel rail for an internal combustion engine is manufactured by stainless steel or is manufactured by steel performed with respect to rust prevention processing on at least the inner face; the diverging branch pipe has a connecting head portion of a cutting head conical shape, an arc shape or an abacus ball shape constituting a pressing face to a partner seating portion in a connecting end portion; the diverging branch pipe is formed by internally mounting a thin inner pipe manufactured by stainless steel in a close fitting shape over the entire circumferential face length of a circulating hole of the axial interior; and the fuel rail for an internal combustion engine and the diverging branch pipe are connected by a nut for fastening through a joint fitting; wherein a seat face is formed by outside bending the tip portion of said inner pipe manufactured by stainless steel so as to cover the tip portion of said connecting head portion; and the seat face and a pressure receiving face of said joint fitting are abutted and engaged; an entire liquid contact portion of the inner circumferential face and the seat face of the diverging branch pipe with respect to the fuel is covered with said inner pipe; and a connecting construction is performed by the nut for fastening. 15. The joint structure of the diverging branch pipe in the fuel rail for an internal combustion engine according to claim 14, wherein the outside bent portion of the inner pipe manufactured by stainless steel and covering the tip portion of said connecting head portion is buried into the connecting head portion so as to be located on the same face as the tip portion of the connecting head portion so that the seat face is formed. 16. A diverging branch pipe in a fuel rail for an internal combustion engine in which the diverging branch pipe in a joint structure of the fuel rail for an internal combustion engine is constructed by a double pipe formed by an outer pipe and an inner pipe; the inner pipe is constructed by a stainless steel pipe or a pipe body having a rust preventing film on the inner circumferential face; the diverging branch pipe is set to a structure for covering an opening end face of the outer pipe with an opening end portion of the inner pipe so as to set the inner circumferential face of the inner pipe to a seat face; an entire liquid contact portion including a seal face with respect to the fuel is covered with said inner pipe; a pressure receiving portion of the inner pipe is supported by said outer pipe; and a spool or a projection as the pressure receiving portion of a nut for fastening is arranged in a terminal portion. 17. The diverging branch pipe in the fuel rail for an internal combustion engine according to claim 16, wherein the rust preventing film of said inner pipe is constructed by a film of plural layers or a diffused single layer of a Ni plating film, a Ni base alloy film, or the Ni plating film and a Ni--P alloy plating film.