Patent GB-1183602-A (GB)
Title: Apparatus having a Rolling-Diaphragm Seal
IPC: F16J3/06
Filed: 1967-03-17
Abstract: 1,183,602. Compressors and hot-gas reciprocating engines. PHILIPS GLOEILAMPENFABRIEKEN, N.V. March 17, 1967 [March 22, 1966], No.12699/67. Headings FIN and F1S. In a piston and cylinder device 1, 2 Fig.2 e.g. a compressor or hot-gas reciprocating engine in which the piston 2 is sealed with respect to the cylinder 1 by a rolling diaphragm 5 supported on the side remote from the gas working space 4 by liquid in a space 6 supplied by pumping means 9, and wherein a control device 10 establishes the correct pressure differential across the diaphragm by allowing the liquid to escape at a controlled rate, the liquid in space 6 is supplemented by gaseous and/or liquid medium 26 supplied directly from the working space 4 or from a space 26, in the event that the desired pressure differential does not exist, e.g. if the liquid volume has leaked away during an inoperative period. The space 6 is filled with liquid by a pump (not shown) or by a pumping ring 9 movable with the piston 2. The control device 10 comprises a diaphragm 12 responsive to the pressure differential across the diaphragm and having a valve member 18 controlling the leakage from the liquid space 6. If the pressure of liquid in the space 6 falls below a predetermined value, a slide 19 also movable by the diaphragm 12 causes pressurization of a duct 29a and consequential opening of a valve 29, whereby liquid is forced through the valve 29 from a chamber 26 separated from a chamber 28 by a piston 27 loaded by gas from the working space 4. In an alternative, the duct opened by the slide 19 communicates the gas in the working space to the liquid space 6. The movement of the diaphragm 12 may cause the mechanical opening of a valve controlling the supply of liquid or gas from an independent source such as a pump, Fig.6 (not shown) or pressurized reservoir, Fig.4 (not shown). In modified arrangements, Figs.3 and 5 (not shown) the control device 10 and chambers 26, 28 are combined to form a single unit. The piston and cylinder device is shown applied to a hot-gas reciprocating engine in Fig. 7. The engine comprises coaxial rods 74, 75 constrained to reciprocate with the required phase difference by a transmission mechanism (not shown). The rod 74 carries a piston movable in a cylinder 70 and sealed thereto by a rolling diaphragm 82 supported by liquid in a space 84 which may be, as described above, supplemented by gas from a working compression space 76. A displacer 73 fixed to the rod 75 varies the volume of an expansion space 77 communicating with the compression space through a cooler 78, a regenerator 79 and a heater 80. The rod 75 is sealed to the piston 72 by a rolling diaphragm 83 supported by liquid in a space 86 supplied by a pumping ring 87 and discharged through an aperture 94 if the pressure differential becomes too small. If the pressure differential becomes too large a check valve 93 opens to admit gas to the space 86 from the compression space 76. The liquid spaces for supporting the diaphragms may be inter-connected, Fig.8 (not shown) whereby both spaces (106, 104) receive gas from a buffer space (81) through a check valve (112) which opens when the pressure differential becomes excessive.