Thermally-controlled valve for a steam trap

A thermally-controlled valve for a steam trap and the like, having a valve seat, comprising:

• a thermally-controlled element including an outer wall portion, an inner wall portion, and a flexible separating wall therebetween, said flexible separating wall comprising a plurality of superimposed membrane lamellae which flex together in the same direction, the outer edges of which and said wall portions are exclusively rigidly welded together, said separating wall and said outer wall portion defining therebetween a receiving chamber for accomodating an expanding medium, said element also including a clamping disk disposed within said chamber and a reciprocably-movable locking member disposed between said separating wall and said inner wall portion for cooperative engagement with the valve seat, said membrane lamellae being rigidly clamped between said clamping disk and said locking member to effect movement of said locking member relative to the valve seat, said locking member having a central cavity and an annular shoulder having an outer generally truncated, cone-shaped circumferential surface which surrounds said cavity and abuts said separating wall and wherein said clamping disk and said membrane lamellae are provided with correspondingly disposed central bores, and complimentary-shaped surfaces opposite said outer circumferential surface of said annular shoulder, said locking member, clamping disk, and membrane lamellae being exclusively rigidly welded together at their adjacent bore or shoulder edges, respectively.