Electromagnetic powder couplings

Claim 1

An electromagnetic powder coupling, comprising: an inner rotor; an outer rotor formed by two pole pieces disposed around and spaced apart from said inner rotor; an air space defined by said inner rotor and said outer rotor adopted to conTain a powdered metal therein; means defining a first annular groove formed in an end of each of said pole pieces comprising a convex cylindrical face and an inner cylindrical face; two lateral cheek pieces disposed at opposite ends of said outer rotor adopted to center said pole pieces comprising said outer rotor with said inner rotor to produce a uniform symmetric air space therebetween each of said cheek pieces having a centering ring disposed thereon defining a concave cylindrical face and an outer cylindrical face, said concave cylindrical face being adopted to mate contiguously when cold against said convex cylindrical face of said annular groove in said pole pieces; a radial clearance defined by said outer cylindrical face of said centering ring of each of said cheek pieces and said inner cylindrical face of each of said annular grooves in said pole pieces when they are cold to allow for thermal expansion of said centering rings and said cheek pieces as they become hot; an excitation coil located partially in each of said pole pieces at an interface between said pole pieces, the face of each of said pole pieces comprising said interface being opposite said ends thereof which contain said first annular grooves; means defining a free space in each of said pole pieces at said interface between said pole pieces, said free spaces being disposed coaxially with each other and extending radially from said excitation coil to said air space; means defining a second annular groove in each of said pole pieces at said interface between said pole pieces, said second annular grooves being disposed coaxially with each other and radially located between said excitation coil and said air space; an amagnetic sleeve partially disposed in each of said annular grooves in said pole pieces coaxially therewith and adopted to be axially-slidable therein to allow said pole pieces to expand freely independently of each other, and to prevent powdered metal from passing from said air space to said excitation coil; and an annular seal located in each of said second annular grooves, each disposed between the base of a different one of said grooves and said amagnetic sleeve to provide an air tight fit between each of said grooves and said sleeve.