Abstract:
A container for containing underwater sensors such as sonar transceivers, sonar imaging devices, optical imaging devices, etc, electronic equipment and a cooling liquid for cooling the electronic equipment is connected to a second, variable volume container which acts both as a heat exchanger and as a pressure compensator for compensating the pressure difference between the cooling fluid and the surrounding water or other fluid.

Description:
FIELD OF THE INVENTION 
       [0001]    The field of the invention is the field of electronics for underwater sonar, sonar and/or optical imaging, and other underwater data and computationally intensive operations. 
       BACKGROUND OF THE INVENTION 
       [0002]    A prior art underwater sonar apparatus is shown in  FIG. 1 . A container  10  contains electronic equipment  12  in a coolant fluid  14 . The electronic equipment  12  is connected through a connection (not shown) to a sonar transceiver  16 , an optical imaging apparatus, or other apparatus for investigation of the surroundings of the container  10 . The container  10  is attached to a ship or to a remotely operated vehicle (ROV) and used to investigate the sea objects therein in the vicinity of the ship or ROV. 
       RELATED PATENTS AND APPLICATIONS 
       [0003]    The above identified patents and patent applications are assigned to the assignee of the present invention and are incorporated herein by reference in their entirety including incorporated material. 
       OBJECTS OF THE INVENTION 
       [0004]    It is an object of the invention to produce an apparatus and method for cooling electronic equipment which is immersed in water or other liquid which can act as a heat sink for the heat produced by the electronic equipment. In addition, the apparatus compensates for the pressure variations between coolant liquid cooling the electronic equipment and the surrounding water. 
       SUMMARY OF THE INVENTION 
       [0005]    A variable volume container is used to transfer heat through the container walls from the coolant cooling electronic equipment to the water surrounding the apparatus of the invention. When the pressure in the coolant rises because the coolant temperature rises, the volume of the container changes to compensate the pressure change. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a sketch of a prior art apparatus for underwater sonar imaging. 
           [0007]      FIG. 2  is a sketch of the prior art apparatus when pressure of coolant fluid 
           [0008]      FIG. 3  is a sketch of the most preferred embodiment of the invention. 
           [0009]      FIG. 4  is a sketch of the most preferred embodiment of the invention when pressure coolant fluid within the container containing electronic equipment rises higher than the pressure of outside cooling water. 
           [0010]      FIG. 5  is a sketch of a preferred embodiment of the invention. 
           [0011]      FIG. 6  is a sketch of a preferred embodiment of the invention. 
           [0012]      FIG. 7  is a sketch of a preferred embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    A container  10  contains electronic equipment  12  in a coolant fluid  14  in the prior art sketch of  FIG. 1 . Heat generated by the electronic equipment  12  and transferred to the coolant fluid  14  is conducted through the walls of the container  10  to the outside water or other fluid  18 . The electronic equipment  12  is connected through a connection (not shown) to a sonar transceiver  16 , an optical imaging apparatus, or other apparatus for investigation of the surroundings of the container  10 . The container  10  is attached to a ship or submarine, to a remotely operated vehicle (ROV), or to an automated underwater vehicle (AUV) and used to investigate the undersea objects therein in the vicinity of the vehicle. 
         [0014]      FIG. 2  shows a sketch of the apparatus of  FIG. 1  when the coolant liquid  14  is heated and expands. The distortion of the container  10  is exaggerated in  FIG. 2  for clarity. However, the distortion is sufficient to change the orientation of sensor  16  with respect to container  10  and to the ship or ROV mounting the container  10 . In addition, the material and walls of container  10  must be much stronger and thicker to withstand the stress needed to hold the pressure of the fluid  14 . The thicker walls mean that the heat transfer coefficient for transferred from the coolant fluid is reduced, and so that the temperature and thus pressure of the coolant fluid must rise yet further. 
         [0015]      FIG. 3  shows a sketch of the most preferred embodiment of the invention. A second container  30  is attached with a fluid connection to the first container  10 . In the embodiment shown, the coolant fluid circulates through the inside of container  10  and the inside of container  30 , and heat is transferred through the walls of container  10  and container  30  to the surrounding cooling water  18 . Of course, the apparatus of the invention may be used for heat exchanging the heat from the coolant liquid to another liquid besides water. 
         [0016]      FIG. 4  shows a sketch of the apparatus of  FIG. 3  when a large heating load is generated by the electronic equipment  12 . The volume of the second container  30  increases to contain the increased volume of the heated cooling fluid  14 . The walls of the second container  30  can now be made very thin, which will make them very flexible and able to increase the volume of the container  30  with little extra cooling fluid pressure over the pressure of the outside water. In addition, the thin walls cut down on the thermal resistance and increase heat transfer. In a preferred embodiment of the invention, the volume of the second container  30  increases by 2% before the pressure inside container  10  is sufficient to distort container  10  unacceptably or to stress the material of container  10  to unacceptable limits. In a more preferred embodiment of the invention, the volume of the second container  30  increases by 5% before the pressure inside container  10  is sufficient to distort container  10  unacceptably or to stress the material of container  10  to unacceptable limits. In the most preferred embodiment of the invention, the volume of the second container  30  increases by 10% before the pressure inside container  10  is sufficient to distort container  10  unacceptably or to stress the material of container  10  to unacceptable limits. 
         [0017]    Optional pumps  40  are shown which can circulate coolant fluid from the inside of container  10  through the inside of container  30  and increase cooling of the cooling fluid  14 . The flow of cooling water is depicted by the arrow  42 . 
         [0018]    Note that if the apparatus of  FIG. 3  is used at great depths, the volume of the second container  30  can decrease to compensate for any compressibility of the cooling fluid  14 . 
         [0019]      FIG. 5  shows a preferred embodiment of the invention, wherein the second container  30  is contained within the first container  10 . In this case, the cooling water circulates within the second container  30 , and the coolant liquid  14  is outside the second container  30 . In the case that the coolant fluid is heated and expands, the volume of the second container  30  is reduced to compensate for the pressure change. An optional scoop is shown to move the outside water or fluid through the second container  30  and increase cooling of the cooling fluid  14 . 
         [0020]      FIG. 6  shows an embodiment of the invention having simple construction and assembly. An array of tubes  60  are inserted through holes in the container  10 , and provide a heat exchanger for exchanging heat between the coolant fluid  14  and the outside water. Optional funnels  62  are shown for funneling outside water through the tubes  60 . If the tubes have thin walls, the heat transfer is maximized and the volume of the tubes will be reduced to compensate the pressure changes within the container  10 . 
         [0021]      FIG. 7  shows a sketch of a preferred embodiment of the invention, wherein the container  30  is a bellows  70  which allows great expansion with modest pressure difference between the coolant fluid  14  and the surrounding water. An optional external shroud  72  is used to protect the bellows  70 , and to provide a channeling flow for the water circulation, as depicted by the arrows 
         [0022]    Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.