Method of making a cooled valve for heat engine and valve obtained thereby

Claim 1

A built-up fluid-cooled poppet valve member construction comprising: a one-piece hollow mushroom head and a stem of substantially round rod-like configuration throughout its length connected in sealing relationship to and projecting endwise from said head; said head including on one side a substantially flat end wall coaxial with and extending substantially transversely of the longitudinal axis of said stem and on the other side a reduced central hub portion coaxial with said stem and terminating in a substantially flat end face parallel to and of smaller extent than said end wall; said head having an inner chamber closed by said end wall and having a threaded bore located opposite to said end wall in coaxial relation with said stem and extending through said hub portion to open into said chamber and to the outside, respectively; said stem having near one end thereof towards said head a peripheral, annular, radially outward projecting flange-like shoulder and an adjacent intermediate threaded section extending from said shoulder towards said one end over a length corresponding substantially to the axial length of said threaded bore; said stem terminating at said one end in a substantially flat transverse end face and also having a coaxial longitudinal bore extending at said one end to and being open at said transverse end face, a tubular pipe element of smaller diameter than said bore and enclosed therein, said element being substantially co-extensive with and disposed in radially spaced relationship with respect to said longitudinal bore thereby defining a pair of cooling fluid conveying concentric ducts, one of which is annular, said pipe element ending recessed axially from adjacent to and being secured directly in sealing relationship to said one end of said longitudinal bore to close off the annular one of said concentric ducts while opening endwise into said one end of said longitudinal bore; said stem extending in screw-threaded engaging relationship through said threaded bore of said hub portion to project bodily into said chamber with said one end abutting endwise with its said flat end face with axially directed thrust pressure contact against said end wall of said head for supporting and backing the latter, and thereby defining an annular cavity within said chamber, said shoulder then bearing against said end face of said hub portion; said stem having adjacent said one end thereof a first port-like passageway providing communication between said chamber and said annular duct and having a second port-like passageway providing direct communication between said chamber and said tubular pipe element via the open end of said longitudinal bore, thereby respectively defining a fluid feed duct and a fluid return duct; at least one of said head and stem having groove means adjacent to said shoulder and the corresponding end of said threaded bore; brazing solder material tightly locking said head and stem together, said brazing-solder material filling all the interstices of junctions between said head and stem and in particular in said groove means and any clearance gaps left between the intermeshing threads of said head and stem, thereby bonding the latter to each other and sealing off the connections therebetween.