Depth control device

Abstract

A depth control device (1) for a subsmersible body comprises a depth monitor (5) and depth controller (6). A variable volume buoyant body operates under the control of the depth controller and comprises three chambers, the first (10) containing air and the second and third chambers (7, 8) containing hydraulic fluid. The second and third chambers (7, 8) communicate reversibly with one another by means of a tube (13) and bypass valve (12) in a pump (3), so that a piston (9) at the entrance to the first chamber (10) is displaced in response to movement of fluid between the second and third chambers. Thus, the volume of the buoyant body is varied and hence the buoyancy of the subsmersible body which it controls. To keep the submersible body at a particular depth, a depth trigger value is set in the depth controller (6), so that a reversible change in the volume of the buoyant body is initiated in response to a change in depth sensed by the depth monitor (5) by pumping fluid between the two chambers (7, 8). The depth monitor is generally a pressure sensor and the pump is typically a swash plate pump.

Dependencies are inferred from the claim text.