Passive controlled buoyancy apparatus
AssigneeThe Charles Stark Draper Laboratory, Inc.
InventorPhilip N. Bowditch
Life of this patent
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Abstract
A passive near neutral buoyancy platform includes a structure housing a series of gas-filled cells, restrained in their maximum volume regardless of the internal charge pressure, and collapsible in character when external pressure exceeds the charge pressure. With this structure, once a cell having a predetermined initial internal charge pressure reaches a depth where the external pressure exceeds this initial value, that cell contracts, resulting in a net buoyancy change for the structure. Where this series of cells is attached integrally to a single structure, the cells form a pre-loaded compressibility compensation device which is matched to the external environment.
Claims9
A passive near-neutral buoyancy platform adapted for submersion in a liquid medium having a compressibility coefficient a.sub.L, comprising:
- a substantially incompressible base structure and n coupled, variable volume hollow cells coupled thereto, where n is an integer, each cell having a predetermined internal charge pressure and including means responsive to the pressure in said liquid exterior to said cell to monotonically vary the volume of said cell between a predetermined minimum and maximum values,
- wherein the compressibility of said platform is a.sub.S, where a.sub.S is less than a.sub.L,
- wherein the internal charge pressure for the i.sup.th cell is P.sub.Ci and where the charge pressures for said cells are successively increasing whereby
- P.sub.Ci <P.sub.C2 <. . . <. . . P.sub.Cn
- wherein the maximum volume for the i.sup.th cell is V.sub.Ci, and the maximum volume for said platform (V.sub.o) equals the sum of the volume of said base structure and ##EQU12## and wherein V.sub.Ci is predetermined so that the density difference between said platform and said liquid equals predetermined negative maximum values when the pressure in said liquid external to said platform equals P.sub.Ci and P.sub.C(i+l), and that pressure equals a predetermined positive value where the rates of change of density of said platform and said liquid with pressure are equal at a pressure between P.sub.Ci and P.sub.C(i+l).
Dependencies are inferred from the claim text.