Structure for connecting branch pipe in high-pressure fuel manifold

A structure for connecting branch pipes in a high-pressure fuel manifold in which each branch pipe is connected to a main pipe for supplying fuel under high pressure through one of a plurality of through-holes which are provided in the peripheral wall of said main pipe in such a manner that said through-holes are spaced apart from each other in the longitudinal direction of said main pipe and are communicated with a flow passage defined inside said main pipe, wherein the improvement comprises:

• a recessed pressure bearing surface provided at the outer end of each of said through-holes so as to open outward divergently;
• a coupled member having an engagement bore axially extending therethrough, and a threaded bore extending laterally into the coupling member to intersect the axial bore, said coupling member being secured to the outer peripheral wall of said main pipe such that said pressure bearing surface is surrounded by said threaded bore;
• said branch pipe having at its end an enlarged pressing top portion and a neck portion contiguous with said enlarged pressing top portion, said enlarged pressing top portion of said branch pipe defining a shoulder adjacent said neck and a converging tip conforming to the shape of the outwardly divergent pressure bearing surface and being seated against said pressure bearing surface, a collar member having an inner cylindrical surface slidably fitted around the neck of the branch pipe, and an end engaged against the shoulder of the branch pipe, said collar member further having a threaded surface defined by its outer periphery;
• and a nut provided around the collar member and the branch pipe, said nut having threaded surfaces respectively provided on its inner and outer peripheries which are threaded in the directions opposite to each other, the inner and outer threaded surfaces of said nut respectively being in thread engagement with the threaded surface of said collar member and said threaded bore provided in said coupling member, whereby rotation of the nut moves the collar relative to the coupling member and against the shoulder of the branch pipe thereby fastening the tip of said branch pipe tightly against the pressure bearing surface of said main pipe.