| 摘要 |
PCT No. PCT/GB94/00779 Sec. 371 Date Nov. 29, 1995 Sec. 102(e) Date Nov. 29, 1995 PCT Filed Apr. 13, 1994 PCT Pub. No. WO94/24468 PCT Pub. Date Oct. 27, 1994A piston reciprocally movable within a cylinder is sealed to the cylinder wall by fluid at a pressure greater than those of the fluids on the opposed sides of the piston supplied to the space (18) between two seals (19, 20) operative between the piston and cylinder wall, an accumulator or auxiliary intensifier chamber (67) being provided from which overpressure fluid is supplied to the space between the two seals to regulate the pressure between them. The two seals between the piston and the cylinder wall can be constituted respectively by first (19A-19C) and second (20A-20C) groups or pluralities of separate seal rings selected as regards material and dimensions so as to perform specific functions. Also, a sealing system between a piston and a cylinder within which the piston is reciprocally movable can comprise a forward seal (19, 20), conveniently having two seals or seal ring groups, separating a process or working fluid (4) being moved by the piston, from a second fluid (7) in the space around the piston, and a rearwardly spaced barrier seal (21A-21C) separating the second fluid from a third fluid filling a housing (6) containing a motor by which the piston is driven.
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