All-metal lift valve for high-vacuum applications

Claim 1

A valve comprising: (a) a housing defining a flow path therethrough; (b) a valve seat member fixedly mounted in said housing and formed with an opening therethrough; (c) a valve member of metallic material, (1) said valve seat member being an annular disc of sheet metal having two opposite major faces and an annular edge portion of rounded contour connecting said major faces, (2) said disc consisting essentially of an outer planar portion and an inner frustoconical portion terminating in said edge portion, (3) said valve member having an annular sealing surface; and (d) actuating means for moving said valve member relative to said valve seat member in a predetermined direction toward and away from a position in which said valve member closes said opening, (1) said edge portion in said position engaging said surface substantially in line contact along a circle, (2) said predetermined direction being obliquely inclined relative to said surface at an angle of less than 30° in all planes perpendicular to said circle, (3) said two major faces defining a median line between said faces in each of said planes, (4) each median line being substantially perpendicular to the engaged sealing surface in the corresponding plane, (5) said sealing surface being a surface of rotation about an axis extending through the center of said circle in said predetermined direction, said surface tapering in the direction of movement of said valve member toward said position, (6) said actuating means including means for applying to said edge portion and to said surface a contact pressure effective to maintain a tightness therebetween corresponding to a helium leakage of not more than 10 -9 torr liter per second, (7) said metallic materials resisting plastic deformation under the applied pressure.