GB837583A - Packing assemblies - Google Patents

Abstract

837,583. Joint-making packings. MISSION MANUFACTURING CO. March 18, 1958 [Sept. 3, 1957], No. 8728/58. Class 122 (3). A packing assembly for sealing the annular space between two parts, such as a cylinder liner 10, Figs. 2 and 3, and a body 11 of a pump, comprises an annular elastic sealing element 12 and deformable back-up rings 13, 14 abutting the ends of the element, each ring having lips 13, 13a and 14, 14a respectively directed towards the sealing element. The sealing element 12, which may be of rubber, is formed with tapered ends, which, as shown in Fig. 3 in undeformed state, abut the curved surfaces 13c, 14c between the lips of the back-up rings 13, 14. The rings 13, 14, which may be of plastic such as nylon and have a small clearance between the walls of the liner 10 and body 11, are arranged so that, when an axial force is applied to the liner, the element 12 is deformed and thereby causes the expanded rubber to act upon the lips and force them into firm contact with the adjacent walls; upon continued pressure on the liner, the element is expanded to completely fill the space between the lips and so make sealing engagement with the walls. As shown in Fig. 2, two packing assemblies are mounted between shoulders 11b, 20 on the pump body 11 and liner 10 respectively and are separated by a non-deformable ring 25 which acts as a support for the plastic back-up rings 13, 14; a hole 27 in the ring leads to an opening 28 for the purpose of detecting leakage. Metal rings 24 may be provided between the back-up rings 13, 14 and the shoulders 11b 20 to provide adequate support should wear occur. The support rings may be moulded or otherwise attached to the back-up rings and in the modification shown in Fig. 12, the element 12 is moulded to the backup rings in which case recesses 112a, 112b are provided in the element to assure that the lips contact the walls before the final sealing engagement therewith of the element. In further modifications, the tapered ends of the element may be flattened or radiused to cooperate with corresponding shapes between the lips of the back-up rings.