Design of buoyancy regulation system for fuel bladder

The buoyancy regulation system of the oil bladder not only provides power for the dive and floating of the water glider, but also the inner layer of the depth control. In order to achieve fast and accurate buoyancy adjustment, it is necessary to measure the net buoyancy value as the feedback amount, and the buoyancy controller. And the buoyancy control system forms a closed loop.

The buoyancy control system of the water glider essentially changes the net buoyancy by changing the volume of the external oil bladder. 

At present, there are two types of methods for changing the volume of the water glider: one is the hydraulic method of using the hydraulic pump to change the volume of the external oil bladder. The other is a heat engine method that changes the volume of the external oil bladder by thermal expansion and contraction of the phase change material. The heat engine method can directly obtain the energy required to achieve its own ups and downs from the environment, greatly reducing the energy consumption of itself. It is limited by the depth of the main stratosphere in different sea areas.

Hydraulic methods are also available in a variety of forms, including single-stroke piston pump and reciprocating piston pumps. The system is a closed electro-hydraulic system consisting of a DC motor, a two-way pump, a check valve, an electromagnetic on-off valve, an internal cylinder and an external oil bladder. The internal cylinder is sealed in a pressure chamber and the external oil bladder is exposed to the outside seawater.

When the oil/fuel in the internal cylinder is delivered to the external oil bladder, the external oil bladder expands and the water glider receives positive buoyancy under the condition of constant mass, and the carrier will float. The process of positive buoyancy is reversed. The one-way valve is combined with the on-off valve to provide an oil path for outward oil discharge and oil return. When the buoyancy is stopped, the check valve and the closed electromagnetic switch valve act as a long-term pressure keeping. At this time, the power of the buoyancy regulating system is turned off to achieve the purpose of energy saving.