Variable Ballast System for Small Submersibles

Abstract

A ballast control system is used which fits small submersible vehicles. The system is used to vary the vehicle ballast in comparison to the surrounding water without the need for the propulsion system to regulate the depth. A piezoelectric fluid pump controls the ballast system and can reach depths to 1,000 ft. The pump moves fluid between an internal reservoir and an external bladder in a very small package and weight. The ballast control system uses typical underwater battery voltages. The pumping system does not need auxiliary devices. The system can be configured to trim the attitude of the vehicle along its longitudinal and/or lateral axes. The invention provides these capabilities with minimal drain on the vehicle's battery system and impact on the vehicle's payload capacity. An emergency system ensures that the submersible vehicle returns to the surface when power is lost.

1 . A ballast system designed for a small submersible vehicle comprising:
 A) a sealed fluid system comprising:
 a) an external bladder, 
 b) a internal fluid reservoir that houses an internal bladder filled with inert gas, 
 c) a control valve, and 
 d) a piezoelectric pump, 
   B) said external bladder is pressurized by a water depth of said submersible vehicle,   C) a ballast control module connected to:
 a) a water depth sensor, 
 b) an external bladder sensor that measures bladder pressure and bladder flow, 
 c) an internal fluid reservoir sensor that measures pressure and temperature of said internal fluid reservoir, d) a navigation controller, e) said control valve, E) said navigation controller inputs a water depth setpoint to said ballast control module, F) said ballast control module programmed to operate said control valve and said piezoelectric pump to move fluid between said external bladder and said internal fluid reservoir according to a depth algorithm, and G) whereby said piezoelectric pump produces fluid flow and pressure to maintain said underwater depth setpoint, said piezoelectric pump is less than  300  cubic inches in size, and said piezoelectric pump weighs less than  10  lbs. 
   
     
     
         2 . The ballast system according to  claim 1 , wherein said piezoelectric pump incorporates a piezoelectric driver, and at least one reed valve. 
     
     
         3 . The ballast system according to  claim 1 , wherein said needed fluid flow is  0 . 25  liters/minute at said needed pressure of  500  psi to operate down to  1 , 000  feet water depth. 
     
     
         4 . The ballast system according to  claim 1 , wherein said small submersible vehicle weighs less than  50  tons. 
     
     
         5 . The ballast system according to  claim 1 , wherein A) a pressurized gas cylinder is connected to said internal bladder by an emergency hydraulic circuit, B) said emergency hydraulic circuit connects said internal bladder to said external bladder, and C) said emergency hydraulic circuit is operable to bring said submersible vehicle to zero depth. 
     
     
         6 . The method of operating a ballast system designed for a small submersible vehicle comprising:
 A) Providing:   a) a sealed fluid system comprising:   i) an external bladder, ii) a internal fluid reservoir that houses an internal bladder filled with inert gas, iii) a control valve, and iv) a piezoelectric pump, b) said external bladder is pressurized by a water depth of said submersible vehicle, c) a ballast control module connected to:   i) a water depth sensor, ii) an external bladder sensor that measures bladder pressure and bladder flow, iii) an internal fluid reservoir sensor that measures pressure and temperature of said internal fluid reservoir, iv) a navigation controller, v) said control valve, B) said navigation controller inputs a water depth setpoint to said ballast control module, C) said ballast control module programmed to operate said control valve and said piezoelectric pump to move fluid between said external bladder and said internal fluid reservoir according to a depth algorithm, and D) whereby said piezoelectric pump produces fluid flow and pressure to maintain said underwater depth setpoint, said piezoelectric pump is less than  300  cubic inches in size, and said piezoelectric pump is less than  10  lbs.   
     
     
         7 . The method according to  claim 6 , wherein said piezoelectric pump incorporates a piezoelectric driver, and at least one reed valve. 
     
     
         8 . The method according to  claim 6 , wherein said needed fluid flow is  0 . 25  liters/minute at said needed pressure of  500  psi to operate down to  1 , 000  feet water depth. 
     
     
         9 . The method according to  claim 6 , wherein said small submersible vehicle weighs less than  50  tons.