Patent GB-767046-A (GB)
Title: Sealing arrangements including toric seals between axially movable inner and outer cylindrical members
IPC: F16J15/00
Filed: 1954-07-05
Abstract: 767,046. Piston and stuffing-box packing. MERCIER, J. July 5, 1954 [July 4, 1953], No. 19571/54. Classes 122 (1) and 122 (5). [Also in Group XXIX] A sealing arrangement between axially movable inner and outer cylindrical members comprises two or more axially spaced sealing rings, at least one of which is an O-ring located in a recess in one of the cylindrical members, a chamber or chambers for leakage fluid in one or the other of the members intermediate said seals, and means to relieve the pressure in said chamber or chambers when it reaches a predetermined amount. A piston 11 operating in a cylinder 10 separates two chambers C<SP>1</SP>, C<SP>2</SP>, and is sealed by two O-rings 14, 15 in grooves 12, 13 in the piston separated by an intermediate chamber C<SP>3</SP>, communicating by a conduit 16 with a supplementary chamber C 4 . The groove 12 communicates with chamber C<SP>1</SP> through conduits 17 and clearance 18 between the piston and cylinder. In normal operation, the pressures P<SP>1</SP> and P<SP>2</SP> in chambers C<SP>1</SP> and C<SP>2</SP> respectively are both greater than the pressure P<SP>3</SP> in chamber C<SP>3</SP> and the O-rings 14, 15 are pressed, by the pressure differentials across them, against the sides of the grooves 12, 13 adjacent chamber C<SP>3</SP>. If the pressure P<SP>3</SP>, exceeds P<SP>1</SP>, due to leakage, the pressure differential is reversed on the O-ring 14 which moves towards the opposite side of the groove 12 and in so doing allows fluid to flow from C<SP>3</SP> to C<SP>1</SP> through conduits 17 and clearance 18, and since P<SP>2</SP> is greater than P<SP>1</SP> the pressure differential on the O-ring 13 is maintained in the same direction. The grooves 12, 13 may be in the cylinder and the groove 12 may have the crosssection shown in Fig. 3 to facilitate the escape of fluid from C<SP>3</SP> to C<SP>1</SP> when P<SP>3</SP> exceeds P<SP>1</SP>. In a modification one of the O-rings is replaced by a flexible lip type packing. In a further modification, three O-rings are used separated by two intermediate chambers. In an hydraulic accumulator. Fig. 7, in which the chambers C<SP>1</SP> and C<SP>2</SP> are connected respectively to the oil system and charged with compressed air and the piston 106 is sealed by two O-rings 107 and 108 separated by chamber C<SP>3</SP>, the pressure in the latter is automatically relieved by a spring-loaded non-return valve 105 communicating with the atmosphere. The chamber C<SP>3</SP> connects with a supplementary chamber C<SP>1</SP>3 filled with foam rubber 110 or other cellular substance. In a modification, Fig. 8 (not shown), the valve 105 is omitted and the supplementary chamber communicates with the chamber C<SP>1</SP> through two spring-loaded non- return valves which respectively allow fluid to pass from C<SP>3</SP> to C<SP>1</SP> and from C<SP>1</SP> to C<SP>3</SP>. In another modification, Fig. 10, the pressure in the chamber C<SP>1</SP>3 is relieved by a valve 170 controlling a passage 171 in the piston end adjacent chamber C<SP>1</SP>, the passage 171 may or may not also be additionally controlled by a spring-loaded ball valve 172. The valve 170 is loaded to open by a spring 173 and to close by the pressure P<SP>2</SP> acting on a head 166 sealingly slidable in a bore in the piston end adjacent the chamber C<SP>2</SP>. In a further modification, Fig. 11, the end of the valve adjacent chamber C<SP>1</SP> is formed as a pump plunger 187 which cooperates with a bore 188 in the piston end which also houses spring-loaded suction and discharge valves 190, 189. According to the Specification, increase in pressure P<SP>3</SP> causes the plunger 187 to move to the right and draw fluid from chamber C<SP>1</SP>3 past the valve 190 into bore 188 with a consequent fall in pressure P<SP>3</SP> resulting in a return movement of the plunger 187 to pump fluid from the bore 188 through the valve 189 into the chamber Cl.