The Perkin-elmer Corporation

Eg&g, Inc.

Brian R Tranter

Nathan R Kane

Michel Villeneuve

An accumulator including a housing with a gas chamber and a liquid chamber therein. A primary piston is moveable in the housing and connected to the housing by a primary bellows sealing the gas chamber with respect to the liquid chamber. A secondary piston is moveable with respect to the primary piston and connected to the primary piston by a secondary bellows sealing the secondary piston with respect to the primary piston.

Accumulator

A method of making a folded metal bellows wherein an n-sided mandrel is positioned within a metal tube at an initial position. A convolution is formed by: axially moving and turning the mandrel with respect to and within the tube from the initial position to a second position. The mandrel is then fixed to the tube and driven towards the initial position while turning the mandrel (and the tube).

Folded metal bellows

A bellows seal arrangement (50) seals a rotating shaft (30) passing through a housing wall (32). The seal uses two bellows (56, 58) of different effective diameters (B, C) that are connected in series by a coupling member (60). The series-connected bellows (56, 58) are fixed to the housing at one end and carry a seal insert (54) at the other providing a seal interface with a seal face member (38) rotating with shaft (30). The coupling member has bridging portions (62, 64) extending parallel to the bellows and spaced from respective stop surfaces (66, 68). Both bellows are responsive to the external pressure (P2) and to the internal (shaft side) pressure (P.sub.1). An excess of either pressure causes the larger effective diameter bellows (56) to expand or contract whereby one of the bridging portions (62, 64) abuts its stop surface (66, 68) to render one or other bellows inactive. By selection of the effective diameters (B, C) of the bellows (56, 58) relative to the internal and external diameter (A, D) of the seal interface the seal interface can be doubly-balanced to any desired degree with respect to both the internal (P1) and external (P2) pressures.

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High Wycombe, United Kingdom

Brian R Tranter