Buoyancy control systems and methods

1. A buoyancy control system for a submersible object submerged in an ambient fluid, comprising:

a piston housing supported by the submersible object;

a piston member defining a piston portion and a shaft portion, where the piston member is supported within the piston housing such that

the piston portion and the piston housing define a control chamber and an ambient chamber, and

the shaft portion and the piston housing define a working chamber;

a pump operatively connected to the working chamber;

control fluid arranged within the control chamber; and

working fluid, where at least a portion of the working fluid is arranged within the working chamber; whereby

operation of the pump displaces working fluid within the working chamber to displace the piston member to alter a volume of the control fluid arranged within the control chamber.

2. A buoyancy control system as recited in claim 1 , further comprising an accumulator operatively connected to the working chamber, where at least a portion of the working fluid is arranged within the accumulator.

3. A buoyancy control system as recited in claim 1 , further comprising a valve operatively connected to the working chamber, where the valve controls the flow of fluid into and out of the working chamber.

4. A buoyancy control system as recited in claim 2 , further comprising a valve operatively connected to the working chamber and to the accumulator, where the valve controls the flow of fluid into and out of the working chamber.

5. A buoyancy control system as recited in claim 1 , further comprising a control system for operating the pump and the valve.

6. A buoyancy control system as recited in claim 1 , in which the control system comprises a position sensor for sensing a position of the piston member relative to the piston housing.

7. A buoyancy control system as recited in claim 1 , in which the control system comprises a depth sensor for sensing a depth of the submersible object.

8. A buoyancy control system as recited in claim 6 , in which the control system further comprises a depth sensor for sensing a depth of the submersible object.

9. A buoyancy control system as recited in claim 1 , further comprising:

a first seal arranged to inhibit flow of fluid between the piston portion and the piston housing; and

a second seal arranged to inhibit flow of fluid between the shaft portion and the piston housing.

10. A buoyancy control system as recited in claim 9 , in which the second seal is arranged to inhibit flow of fluid between the control chamber and the working chamber.

11. A buoyancy control system as recited in claim 1 , in which the piston portion defines:

a control surface that acts on the control fluid; and

an ambient surface that acts on the ambient fluid.

12. A buoyancy control system as recited in claim 1 , further comprising a filter arranged to filter the working fluid.

13. A method of controlling the buoyancy of a submersible object submerged in an ambient fluid, comprising the steps of:

securing a piston housing to the submersible object;

providing a piston member defining a piston portion and a shaft portion,

supporting the piston member within the piston housing such that

the piston portion and the piston housing define a control chamber and an ambient chamber, and

the shaft portion and the piston housing define a working chamber; and

operatively connecting a pump to the working chamber;

arranging control fluid within the control chamber;

providing working fluid;

arranging at least a portion of the working fluid is arranged within the working chamber; whereby

operating the pump to displace working fluid within the working chamber, thereby displacing the piston member to alter a volume of the control fluid arranged within the control chamber.

14. A method as recited in claim 13 , further comprising the steps of:

operatively connecting an accumulator to the working chamber; and

arranging at least a portion of the working fluid within the accumulator.

15. A method as recited in claim 13 , further comprising the steps of:

operatively connecting a valve to the working chamber;

operating the valve to control the flow of fluid into and out of the working chamber.

16. A method as recited in claim 15 , in which the step of operating the valve comprises the step of sensing a position of the piston member relative to the piston housing.

17. A method as recited in claim 16 , in which the step of operating the valve comprises the step of sensing a depth of the submersible object.

18. A buoyancy controlled object to be submerged in an ambient fluid, comprising:

a hull assembly;

a piston housing rigidly connected to the hull assembly;

a piston member defining a piston portion and a shaft portion, where the piston member is supported within the piston housing such that

the piston portion and the piston housing define a control chamber and an ambient chamber, and

the shaft portion and the piston housing define a working chamber;

a pump operatively connected to the working chamber;

an accumulator operatively connected to the working chamber;

a valve operatively connected to the working chamber;

control fluid arranged within the control chamber; and

working fluid, where at least a portion of the working fluid is arranged within the working chamber and at least a portion of the working fluid is arranged in the accumulator; whereby operation of the pump displaces working fluid within the working chamber to displace the piston member to alter a volume of the control fluid arranged within the control chamber; and

operation of the valve controls the flow of working fluid into and out of the working chamber.

19. A buoyancy control system as recited in claim 18 , further comprising a control system for operating the pump and the valve based on at least one of:

a position of the piston member relative to the piston housing; and

a depth of the submersible object.

20. A buoyancy control system as recited in claim 19 , further comprising:

a first seal arranged to inhibit flow of fluid between the piston portion and the piston housing; and

a second seal arranged to inhibit flow of fluid between the control chamber and the working chamber between the shaft portion and the piston housing.