Abstract:
A hydrostatic release for securing an emergency position indicating radio beacon (EPIRB) to a shipboard surface to withstand high G-forces while having a release mechanism that if the ship were to sink will release the EPIRB at a pre-determined water pressure which is equivalent to depth of water. The hydrostatic release includes two shafts mounted end to end and clamped together under spring pressure by a slide that can be moved by a water pressure sensitive diaphragm when the hydrostatic device is underwater and experiences a pre-determined water pressure. The elongated shaft is connected at one end to an EPIRB housing and at the other end to the EPIRB housing cover. Once the cover is released by the water pressure, the EPIRB will float to the ocean surface.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to an underwater pressure-activated hydrostatic release for physically securing an emergency position indicating radio beacon (EPIRB) to a vessel and physically automatically releasing the EPIRB from the vessel in the event that the vessel sinks. 
   2. Description of Related Art 
   An emergency position indicating radio beacon (EPIRB) is a device that transmits signals at radio frequencies to announce an emergency and to help locate the victims of the emergency typically when a boat or a ship sinks. Most often, the EPIRB transmitters are activated upon immersion in water which causes an electric contact to activate the transmitters. The emergency signals can be picked up by satellites, airplanes or other ships in the vicinity while the EPIRB is floating on the surface of the ocean. 
   When not in use, however, the EPIRB must be securely stored and fastened to a vessel especially because boats and ships are subject to high G-forces due to wave action and the rolling action of the vessel under certain meteorological conditions. Thus, in the absence of an emergency, the EPIRB is typically mounted in a moisture resistant housing since exposure to water immersion can set off the transmitter leading to a false emergency signal. However, if the vessel sinks, water can flow into the moisture resistant EPIRB housing because it is absolutely essential that the EPIRB be released by water pressure from the vessel and from the housing within which it is stored so that the EPIRB can rise to the surface of the ocean and begin transmitting an emergency signal as quickly as possible. 
   One aspect of the present invention addresses this problem by providing a water pressure activated hydrostatic release that when not activated securely fastens the EPIRB in a secure housing to a vessel and when activated underwater by the surrounding water pressure releases the EPIRB and the secure housing cover based on hydrostatic pressure resulting from underwater pressure. Once the secure housing cover is released underwater, the EPIRB is free to float to the surface. 
   SUMMARY OF THE INVENTION 
   The hydrostatic release is its own self-contained unit that can securely connect a first object to a second object mechanically. An EPIRB is securely stored in a protective two piece housing, the base of which is securely fastened to the hull or deck of a ship or boat. The housing base is a receptacle that is large enough to receive the EPIRB and the static release device. The EPIRB housing includes a top cover that fits over the EPIRB and the hydrostatic release device which are stored inside the housing base. The housing cover is secured to the housing base receptacle by connection to the hydrostatic release device, stored inside the housing. Thus, in the stored position, the EPIRB (which floats) rests inside the closed moisture resistant housing along with the hydrostatic release device which is fastened to the housing base and also fastened to the cover, holding the cover securely in place on the housing base. If the ship or vessel attached to the EPIRB housing sinks, the EPIRB housing and its contents also sink underwater. Water is received in the EPIRB housing. At a certain underwater pressure (a certain water depth), the hydrostatic release will be activated which then releases the EPIRB housing cover from the housing base receptacle. Once the housing cover has been released by the hydrostatic release, the EPIRB will float because of its buoyancy to the surface of the ocean or body of water and will begin transmitting emergency signals. 
   The following description discusses the structure and operation of the hydrostatic release mechanism. 
   The hydrostatic release includes an elongated vertical shaft that is in two pieces including an upper release pin and a lower base pin that when joined together by a slide includes a first locking flange and a second locking flange. The two piece elongated shaft is held firmly in place as if it were one shaft by the locking pins. 
   The hydrostatic release includes a compartment having a diaphragm under a first spring tension that moves against the spring due to water pressure on one side releasing a slide mechanism that locks the first and second shaft pieces together. When sufficient water pressure engages the diaphragm, which would be the case when a boat sinks with the hydrostatic device attached thereto and reaches a certain depth of water, there is sufficient water pressure to move the diaphragm on one side against spring tension that releases tension on the slide mechanism which is under a second spring tension. When that happens, the slide moves away from the elongated shaft, disengaging the release pin from the base pin which is secured to the EPIRB housing cover. Once the release pin is free, the upper housing cover of the EPIRB and the EPIRB itself are free to float away. The EPIRB is buoyant and floats to the surface. Once water engulfs the EPIRB, the device will automatically begin transmitting emergency signals. 
   An object of this invention is to produce an inexpensive, effective, and reliable pressure-activated release mechanism for securing an EPIRB to a vessel and for releasing the EPIRB as the vessel to which the EPIRB is attached begins sinking. 
   Another object of this invention is to use an apparatus that is activated by changes in pressure or depth for releasing a device, such as an EPIRB, from a vessel rather than using a cutting latch mechanism. 
   In accordance with these and other objects which will become apparent hereinafter, the instant invention will now be described with particular reference to the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  shows a perspective top view of the hydrostatic release mechanism. 
       FIG. 1B  shows a perspective bottom view of the hydrostatic release mechanism. 
       FIG. 2  shows an elevational side view of the hydrostatic release mechanism. 
       FIG. 3  shows an elevational front view of the hydrostatic release mechanism. 
       FIG. 4  shows an elevational rear view of the hydrostatic release mechanism. 
       FIG. 5  shows a top plan view of the hydrostatic release mechanism. 
       FIG. 6  shows a bottom plan view of the hydrostatic release mechanism. 
       FIG. 7  shows an exploded perspective view of the hydrostatic release mechanism. 
       FIG. 8  shows a cross-sectional, elevational, side view of the hydrostatic release mechanism. 
       FIG. 9  shows a side elevational view of the piston diaphragm assembly. 
       FIG. 10  shows an exploded view of a shelter and its housings, the hydrostatic release, the EPIRB, and a cotter pin. 
       FIG. 11  shows a cut-away side elevational view of the sealed shelter with the hydrostatic release and EPIRB couched within said sealed shelter. 
       FIG. 12  shows a perspective view of the bottom housing of the shelter attached to the surface of a vessel and having the hydrostatic release and EPIRB couched within said bottom housing of the shelter. 
   

   DETAILED DESCRIPTION 
     FIGS. 1 through 6  illustrate the hydrostatic release mechanism  10  for securing an emergency position indicating radio beacon (EPIRB)  12  ( FIG. 10 ) to a vessel  14  ( FIG. 11 ) and for releasing said EPIRB  12  from the vessel during an emergency when said vessel  14  is sinking. The EPIRB is mounted in a protective housing  46  and  48  ( FIG. 10 ) that must be securely fastened to the vessel to prevent release of the EPIRB during high G-motion of the vessel during normal operation of the vessel. The EPIRB must be secured in the protective housing until the emergency. 
   The hydrostatic release  10  includes its own housing having a cover  16 , a base receptacle  18 , a midplate bushing  20 , a piston diaphragm assembly  22 , a slide spring  24 , a slide  26 , a diaphragm spring  28 , a plug  30 , a plug retainer  32 , an upper rod  34 , a lower rod  36 , and a tamper-proof insert  38 . The hydrostatic release  10  uses a two-part rod design (upper rod  34  and lower rod  36 ) to release the EPIRB  12 , rather than using knife or razor blades or another cutting action elements as with conventional EPIRB releases. Through a horizontal cross-section, the top housing  16  is substantially pear-shaped, having a round end  16   a  and a tapered end  16   b  as shown in  FIG. 5 . Similarly, the bottom housing  18  and midplate bushing  20  are also substantially pear-shaped with each having a round end,  18   a  and  20   a  respectively, and a tapered end,  18   b  and  20   b  respectively, so that said top and bottom housings,  16  and  18 , and the midplate bushing  20  fit together when aligned geometrically as the hydrostatic release  10  is assembled. 
   In  FIG. 5  and  FIG. 8 , the top housing  16  of the hydrostatic release  10  comprises a recessed interior surface  16   d , an exterior surface  16   e , and a side wall  16   f . The top housing  16  also includes a top housing aperture  16   c , which is centrally disposed on and passes through the tapered end  16   b  of said top housing  16 . A first end  34   a  of the upper rod  34  is inserted into the top housing aperture  16   c  until said first end  34   a  contacts the first end  36   a  of said lower rod  36  as shown in  FIG. 8 . The top housing  16  is connected securely to the bottom housing  18  in a clam-shell configuration to seal all of the aforementioned components within the hydrostatic release  10 . Said top housing  16  further includes an air-breathing aperture  16   g.    
   The bottom housing  18  of the hydrostatic release  10  comprises a planar exterior surface  18   c  having a midline ridge  18   d  and a recessed interior surface  18   e  surrounded by a shallow side wall  18   f  connected at approximately right angles to said interior surface  18   e . The bottom housing  18  is penetrated by a bottom housing aperture  18   g , which is centrally disposed on and passes through the tapered end  18   b  of said bottom housing  18 . The lower rod  36  is inserted into the bottom housing aperture  18   g . The bottom housing  18  further includes a channel  18   h  disposed centrally and longitudinally across the interior surface  18   e.  Said channel  18   h  on the interior surface  18   e  of the bottom housing  18  corresponds to and forms the midline ridge  18   d  on the exterior surface  18   c  of the bottom housing  18 . The channel  18   h  is constructed of a sufficient size to receive the insertion of slide  26 . The slide spring  24  fits within the channel  18   h  and the slide  26  is fitted over the slide spring  24  and within the channel  18   h  of the interior surface  18   e . Said bottom housing further includes two water-intake apertures  18   k  as shown in  FIG. 6 . 
   The midplate bushing comprises a mostly planar circular portion  20   d  located on the round end  20   a  of said midplate bushing  20 , a first aperture, and a centrally-located second aperture  20   e . The midplate bushing  20  is fitted mostly within an interior void  40 , or pressure chamber, formed between the top housing  16  and bottom housing  18  above the slide  26  and slide spring  24  when the assembly of the device  10  is complete. As illustrated in  FIG. 7 , the first aperture  20   c  of the midplate bushing  20  receives the upper rod  34  that is inserted through the top housing aperture  16   c . According to  FIGS. 2 through 4 , the midplate bushing  20  is interposed, or sandwiched, between the top housing  16  and bottom housing  18 . The midplate bushing  20  remains visible when the hydrostatic release  10  is fully assembled. 
   The slide  26 , which is fitted over top of the slide spring  24  both of which are seated within the channel  18   h  of the bottom housing  18 , comprises a first locking flange  26   a  and a second locking flange  26   b  that are located on one end of said slide  26 . Said slide also includes a pin-receiving aperture  26   c . The first and second locking flanges  26   a  and  26   b  engage and secure the upper and lower rods  34  and  36  within the hydrostatic release  10 . The slide  26  is substantially rectangular in shape and is hollow, having an open bottom, for receiving and fitting over the slide spring  24  when seated within channel  18   h.    
   The sealing of the top housing  16  to the bottom housing  18  creates the interior chamber  40  in  FIG. 8 . As the vessel sinks, water enters through the water-intake apertures  18   k  of the bottom housing  18  and forces against the diaphragm  22   b . The opposite of the diaphragm  22   d , within the chamber  40  contains air which is exhausted out through the air-breathing aperture  16   g  during activation. In this manner, the pressure exerted by the water as a vessel  14  sinks to greater depths activates the pressure-actuated slide spring  24 , which allows the upper rod  34  to be released. Once the upper rod  34  is released, the EPIRB  12  floats to the surface and emits a distress radio signal detected by satellites or other means, which relay the emergency signal to land-based rescue stations. 
   In  FIG. 7 , the piston diaphragm assembly  22  is fitted onto the planar circular portion  20   d  of the midplate bushing  20 . The second aperture  20   e  of said midplate bushing  20  receives a pin  22   a  that is solidly attached to the center of the inferior surface  22   b  of the piston diaphragm assembly  22 . A cylindrical piston  22   c  centrally-positioned and solidly attached to the superior surface  22   d  of the piston diaphragm assembly  22  is inserted into a first end  28   a  of the diaphragm spring  28 . The plug retainer  32  is fitted over a second end  28   b  of the diaphragm spring  28  and the plug  30  is engaged with said plug retainer  32  on an opposing side of the plug retainer  32 . Preferably, the plug  30  is constructed from P.T.F.E. or another similar material and is cylindrical in shape. 
   The lower rod  36  comprises a first end  36   a  and a second end  36   b . The second end  36   b  protrudes from the bottom housing  18  of the hydrostatic release  10  once the top and bottom housings  16  and  18  are sealed together. Said second end  36   e  of the lower rod  36  includes a key feature  42  for locking the lower rod  36  to a bracket (not shown in the drawings) on the surface of the vessel or to an attachment means within a clam-shell shelter  44 , as illustrate in  FIGS. 10 through 12 . The first end  36   a  of the lower rod  36  has a necked flange  36   c  comprising a small, preferably cylindrical, support shaft  36   d  that supports a centrally-positioned cylindrical plate  36   e . The lower rod  36  further includes an aperture  36   f  that passes vertically through said second end  36   e.    
   As shown in  FIG. 8 , the diameter of the cylindrical plate  36   d  of the necked flange  36   b  is greater than the diameter of the support shaft  36   c . Immediately below the support shaft  36   c , said first end  36   a  of the lower rod  36  has an annular flange  36   h  with a diameter that is also greater than the diameter of the support shaft  36   c . The cylindrical plate  36   d  and annular flange  36   h  along with the support shaft  36   c , which has a smaller diameter and is disposed solidly between said cylindrical plate  36   d  and annular flange  36   h  that are of greater diameters, forms a locking groove  36   h  that receives the first locking flange  26   a  of the slide  26 . 
   The upper rod  34  of the hydrostatic release  10  also comprises a first end  34   a  ( FIG. 7 ) and a second end  34   b  ( FIG. 7 ). The first end  34   a  of the upper rod  34  includes a necked flange  34   c  that is comprised of a small, preferably cylindrical, support shaft  34   d  supporting a centrally-positioned cylindrical plate  34   e . The diameter of the cylindrical plate  34   e  is greater than the diameter of the support shaft  34   d . Likewise, immediately below the support shaft  34   d , said first end  34   a  of the upper rod  34  has an annular flange  34   f  with a diameter that is also greater than the diameter of the support shaft  34   d . The support shaft  34   d , having a smaller diameter and being disposed solidly between the cylindrical plate  34   e  and annular flange  34   f  of larger diameters, forms a locking groove  34   g  that receives the second locking flange  26   b  of the slide  26 . The second end  34   b  of the upper rod  34  protrudes from the top housing  16  of the hydrostatic release  10  once the top and bottom housings  16  and  18  are sealed together. The second end  34   b  of the upper rod  34  also includes an aperture  34   h  that passes horizontally through said second end  34   b  for receiving a cotter pin  50 . 
   As illustrated in  FIGS. 10 through 12 , the hydrostatic release  10  is housed within the clam-shell shelter  44 , which protects both the EPIRB  12  and the hydrostatic release  10  from exposure to the elements and particularly from exposure to saltwater. The shelter  44  comprises a top housing  46 , a bottom housing  48 , a void  52  formed between the top and bottom housings  46  and  48  once assembled, and a rod aperture  54  located through a top surface of the top housing  46 . The shelter  44  preferably is mounted on an exterior wall of the vessel  14  so as to be in an unobstructed location for releasing the buoyant EPIRB  12  should the vessel begin to sink. Both the EPIRB  12  and the hydrostatic release  10  are couched within the void  52  within shelter  44 . The upper rod  34  of the hydrostatic release protrudes from the rod aperture  54  of the top housing  46 . The cotter pin  50  is inserted through the aperture  34   h  of the upper rod  34  to secure the top housing  46  to the bottom housing  48  of the shelter  44 . As the vessel  14  sinks and pressure increases as the depth of the sinking vessel increases, the hydrostatic release is activated and the upper rod  34  is released, thereby also releasing the top housing  46  of the shelter  44 . Once the top housing  46  is released, the buoyant EPIRB  12  freely floats to the surface of the water. 
   The first locking flange  26   a  and second locking flange  26   b  of the slide  26  press in contact against the locking grooves  34   g  and  36   h  of the upper and lower rods  34  and  36 , thereby securing the EPIRB  12  to the surface of the vessel  14 . When water enters the release mechanism through water-intake aperture  18   k , the resulting increase in pressure, caused by the sinking of the vessel  14  to greater and greater depths in the water column, actuates the diaphragm spring  28  and piston diaphragm assembly  22 . The piston  22   c  moves in an upward stroke, thereby causing the simultaneous upward movement of the pin  22   a . In moving upward, said pin  22   a  of the piston diaphragm assembly  22  disengages from the pin-receiving aperture  26   c  of the slide  26  by being withdrawn through said pin-receiving aperture  26   c  and through the second aperture  20   e  of the midplate bushing  20 . Once the pin  22   a  of the piston diaphragm assembly  22  is removed, the compressed slide spring  24  uncoils and pushes the slide  26  from a first end  18   i  starting position, through the channel  18   h  of the bottom housing  18 , and to a second end  18   j  of said channel  18   h  that is farthest from the upper and lower rods  34  and  36 . At that instant, the first and second locking flanges  26   a  and  26   b  of slide  26  are also pushed away from said upper and lower rods  34  and  36 . The upper rod  34  freely disengages from the hydrostatic release  10  and withdraws from the top housing aperture  16   c . The EPIRB  12  then floats to the surface of the body of water. 
   The EPIRB is secured to the vessel during all violent motions to the vessel due to wave action but dependably releases the EPIRB in an emergency such as sinking. 
   The components of the hydrostatic release  10  may be ultrasonically welded together, which eliminates the need for additional manufacturing hardware and increases the speed of assembly of the devices. Two additional features of the hydrostatic release  10  allow the component and system integrity of each hydrostatic release mechanism to be tested for performance prior to shipment without replacing components, such as strings or lines that are cut through in conventional EPIRB releases. First, the hydrostatic release  10  allows non-destructive activation unlike conventional devices that employ knives, razors, or other mechanical cutting means to release an EPIRB. Secondly, the hydrostatic release cannot be reset by the user, which prevents tampering. 
   The instant invention has been shown and described herein in what is considered to be the most practical and preferred embodiment. It is recognized, however, that departures may be made therefrom within the scope of the invention and that obvious modifications will occur to a person skilled in the art.