Patent GB-903391-A (GB)
Title: Improvements in packings comprising an annular resilient sealing element
IPC: F16J15/34
Filed: 1958-12-01
Abstract: 903,391. Stuffing-box substitutes; piston packing; joint-making packing. STUMPFIG, F. Dec. 1, 1958, No. 38693/58. Classes 122 (1), 122 (3) and 122 (5). An annular packing comprises a movable sealing lip f, Fig. 1, constantly pressed against a movable or stationary surface by a resilient ring e which is subject to initial stress and is in the form of a torsionally resilient ring held with such freedom in its mounting that, in its condition of use, it can yield resiliently above an annular torsion axis whose diameter remains unaltered during such yielding and is intermediate in size between the diameter of the outer and inner edges of the ring. As shown applied to sealing the gap c between a rotary or reciprocating shaft a and housing b, the sealing ring e, which is of rubber or synthetic resin, is of part-spherical cross-section and mounted loosely in a corresponding groove d in the housing. The diameter of the inner sealing edge f of the ring, before assembly of the shaft, is less than the diameter of the latter so that when the shaft is assembled the ring e is twisted about its annular torsional axis, thereby causing the edge f to sealingly contact the shaft; the pressure of the fluid being sealed also acts upon the ring to increase the sealing contact. In the embodiment shown in Fig. 2, a hollow ring of synthetic material is provided with an internal annular metal spring having a ring portion h effecting the torsional action and spring fingers i, k extending therefrom for urging the sealing ring into contact with the groove d and shaft a; pressure fluid may enter the hollow ring and increase the sealing contact. If desired, the synthetic material and the metal spring may be vulcanized together. In the modification shown in Fig. 3, the ring e which is formed with an acute-angled cross-section and has inserted within it a torsion spring h, is disposed in the free space between a shaft a and its housing b and a peripheral flange l on ring e may engage a corresponding groove in the housing to prevent axial movement of the ring without affecting the above-described torsional action of the ring; the ring e is twisted bodily when inserted in position in order to provide the initial torsional stress. A sealing ring similar to that of the latter modification is formed with an obtuse-angled cross-section (Fig. 9, not shown), its inner edge then being arranged to have rubbing contact with a collar on the shaft. As shown in Fig. 6, applied to the sealing of a bearing, the ring e is so loosely mounted in a groove u in the outer bearing ring that it can yield about its torsional axes, its lip being pressed resiliently into sealing engagement with the inner bearing ring ; the ring e may be made of synthetic resin, rubber or spring metal, or of spring metal coated with synthetic resin or rubber. The arrangement of Fig. 6 may be modified by arranging for the ring e to be urged into sealing engagement with the inner bearing ring and the groove u by a radiallyslotted torsion ring, an extra spring ring being provided, if desired, for urging the ring e into contact with the groove u in which it has the necessary freedom for movement. In the embodiment shown in Fig. 4 applied to a piston, the sealing ring e is pressed from flexible sheet metal and formed with both a discshaped upper portion o and corrugated lower portion p having a sealing lip f engaging the cylinder liner m ; the ring is located loosely in a groove in the piston so that the annular edge q of the portion o abuts the upper edge of the groove and serves as the torsional axis of the ring. A part-spherical metal ring e, Fig. 4, seals the gap between the cylinder liner and head S. If desired, a plurality of packings constructed as described above may be arranged in series or as a labyrinth packing.