Apparatus for tying moving blades

Claim 1

In a rotary fluid machine having a rotor with an annular array of generally radially extending blades with radially inner and outer ends, the improvement being in apparatus for tying the blades together between their inner and outer ends, comprising: said blades having a plurality of pairs of projections, each pair of projections consisting of a first projection provided on one of said blades and a second projection provided on the adjacent blade in facing relationship with respect to said first projection, each of said first projections having a bearing surface and each of said second projections having a bearing surface facing the bearing surface of said first projection of said pair, and at least part of said bearing surfaces of each pair increasing in tangential distance from each other toward the axis of rotation; a plurality of tying members separate from said blades and corresponding in number to the number of said pairs of projections, each of said tying members extending between the bearing surfaces of a corresponding pair of projections, each of said tying members having bearing surfaces at their opposite ends of mating shape with the corresponding bearing surfaces of said first and second projections, and each of said tying members being mounted for limited radial movement outwardly with respect to its adjacent blades; said mating bearing surfaces engaging each other around the entire annular array of said blades during rotation of the rotor to provide wedge means for applying tangential forces between adjacent blades resulting from the centrifugal forces acting upon and radially outwardly moving said tying members to interbrace the blades tangentially around the array at a predetermined speed of the rotary fluid machine and restrain tangential vibrations; at least the cooperating first projections and adjacent ends of the tying members associated therewith having means positively restraining rotation of the tying member about a line drawn between its opposite bearing surfaces; said engaging bearing surfaces of said projections and tying members being at least partly arcuate in shape as viewed in a tangential plane passing through them for each pair to provide means for permitting relative axial movement between the adjacent projections of each pair of projections as caused by twisting of each blade about its radial extent; the bearing surfaces for each of said tying members including spherical portions and at least one planar portion that is perpendicular to the radial direction, and each of said projections having a recess receiving therein said spherical portions and said planar portion of the tying member with substantial clearance at least in the radial direction for said planar portion when the rotor is at rest; said recesses and planar portions at least in part constituting said means restraining motion.