Patent GB-1005591-A (GB)
Title: Improvements in or relating to devices incorporating rolling diaphragm seals
IPC: F16J3/06
Filed: 1962-06-13
Abstract: 1,005,591. Diaphragm seals. PHILIPS GLOEILAMPENFABRIEKEN N.V. June 13, 1962 [June 16, 1961], No. 22727/62. Headings F2B and F2T. A rolling diaphragm seal 11, Fig. 1, between an element 13, e.g. a piston or rod, coaxially reciprocable within another element 12, e.g. a cylinder or sleeve, separates a space I containing fluid medium from a space II completely filled with a substantially incompressible medium, such as a liquid or granular material, and bounded by the diaphragm and rigid walls, the volume of the space II remaining constant or substantially so during reciprocation of the element 13. The diaphragm 11 is fixed to both elements and is made of elastic material. The pressure in the space I exceeds that in the space II. As the element 13 moves upwards, the resulting displacement of the diaphragm would tend to bring an increase in volume of the space II exceeding the reduction caused by movement of the enlarged lower portion of the element 13. This increase in volume is compensated by deformation of the elastic diaphragm by the excess pressure in the space I whereby the space II is always kept completely filled with the incompressible medium. Alternatively, the concave side of the diaphragm faces the space II and the pressure of the incompressible fluid is higher than that of the fluid medium in space I. In Fig. 3, the surface portions a, b, c and d, g, f of the elements 32, 33 are so shaped that during movement of the element 33 the volume of the space II is maintained constant without alteration in the cross-sectional length of the diaphragm. In Figs. 5 and 7b the relative dimensions of the elements 52, 53 and 72, 73 respectively and of those parts of the elements bounding the space II are such that the increase in volume due to the displacement of the diaphragm is exactly compensated by the decrease in volume produced by the displacement of the parts 53 and 73 respectively, the cross-sectional length of the diaphragm remaining constant. In Fig. 8, the walls a, b, c, i and d, f, g, h of the space II are so constructed that both its volume and the cross-sectional length of the diaphragm remain constant during reciprocation of the element 83. A portion 85 of the wall d, f is porous, e.g. of sintered material, or is formed with an outlet port, and communicates via a passage 86 with an oil container 87 from which oil is drawn into the space II by a control ring 84 at a rate equivalent to that at which leakage of oil occurs from the space. If excess oil is fed to the space II the diaphragm will be deformed so as to uncover the portion 85 and the excess oil will flow back to the container 87. The diaphragm may be covered with diffusion resistant material. In Fig. 9 the diaphragm 91 is provided between a cylinder 92 and a piston 93, the spaces I, II containing respectively a fluid subjected to pressure fluctuations and oil, and communicating via conduits 97, 98 with opposite sides of a diaphragm 100 in a housing 99. If the volume of oil increases in the space II due to an excess being fed by the control ring 94, the pressure difference on the diaphragms 91, 100 is reduced. When the pressure difference on the diaphragm 100 drops below a certain value and valve 101 attached to the diaphragm is unseated from the top of an outlet pipe 102 and allows excess oil to escape therethrough until the difference between the pressures in spaces I, II is restored to the desired value.