Protective enclosure for apparatus placed in a hyperbaric pressure tight chamber
United States Patent 1191 Martin et a1.  
 1451 Apr. s, 1975 PROTECTIVE ENCLOSURE FOR APPARATUS PLACED IN A I&#39;IYPERBARIC PRESSURE TIGHT CHAMBER [75] Inventors: Gilbert Marius Henri Martin, La  
 Seyne; Jean Claude Fournier, Toulon, both of France [73] Assignee: Etat Francais represente par le Delegue ministeriel pour larmement, Paris, France 221 Filed: Sept. 25, 1973 211 Appl. No.: 400,611  
 [30] Foreign Application Priority Data V 26 a e H 4 vmmgg Primary Examiner-Richard M. Sheer Attorney, Agent, or FirmLarson, Taylor and Hinds [57] ABSTRACT An appliance adapted to be placed in a high-pressure pressure tight chamber wherein there is provided a passageway leading from the interior of the appliance through to the exterior of the pressure tight chamber so that the interior of the appliance may operate at atmospheric pressure while a higher pressure is created within the chamber. A tubular body may be located within the chamber wall having a passageway therethrough with a control valve at the outer end thereof. This body may communicate with suitable means to the appliance itself which may comprise a base, the applicance elements itself on one side of the base enclosed by a protective enclosure and including a passageway through this base. A reduced cross-section nozzle may be provided in this conduit to prevent the high-pressure gases in the chamber from flowing out through the passageway if the protective enclosure breaks.  
 10 Claims, 2 Drawing Figures PROTECTIVE ENCLOSURE FOR APPARATUS PLACED IN A HYPERBARIC PRESSURE TIGHT CHAMBER BACKGROUND OF THE INVENTION This invention relates to apparatus subjected to high internal pressures, and in particular it relates to protective enclosures for apparatuses, appliances or the like placed into a hyperbaric pressure tight chamber also known as a caisson.  
  lt is known that for experimental or training purposes for depth conditions, it is current practice to have the personnel who are to be trained for such depth conditions such as submarine missions spend some time in a hyperbaric pressure tight chamber. It is also known that subsequent to diving accidents, generally when the patient suffers from gas embolism, he undergoes reconditioning treatment which requires that he be placed in depth conditions, i.e., within a hyperbaric pressure tight chamber. It is also known that these pressure tight chambers are pressurized with helium or hydrogen and that they are especially designed so that there will be no abrupt, considerable reduction of pressure occurring by accident.  
  Such pressure tight chambers are equipped with various apparatus, appliances and the like which, not being capable of withstanding excessive pressures without the risk of accident, are disposed in enclosures inside of which atmospheric pressure is permanently sustained. This is the case for example with illuminating lamps or with different electronic equipment which necessarily must be protected from said high-pressures within the chamber. However, in the case of certain appliances such as sealed illuminating lamps, it has been found that the gases such as helium difuse into the substance enclosing the lamp and then contacts the elements of the lamp which themselves release a considerable amount of heat. As a result, excessive internal pressure is created which can cause an explosion of the lamp, especially upon decompression of the high-pressure chamber.  
  Thus, there exists a need for a new and improved arrangement for rendering more safe such appliances, apparatus and the like for use in hyperbaric pressure tight chambers.  
 SUMMARY OF THE INVENTION Thus, it is a goal of the present invention to provide a safer apparatus, appliance or the like for use in a high-pressure chamber which will allow permanent maintenance of atmospheric pressure within the enclosure while concurrently ensuring that if in fact an explosion does occur, the high-pressure conditions within the chamber will not be lost.  
  This goal of the present invention is attained by providing a protective enclosure for use with an apparatus, appliance or the like placed in a high-pressure chamber and comprising means defining a passageway from the interior of the protective enclosure to and through the wall of the high-pressure chamber. This passageway includes a means for limiting the gas flow therethrough such that if in fact the protective enclosure breaks, the pressure within the high-pressure chamber cannot be suddenly reduced by a rapid flow of gas through the passageway.  
  In a preferred embodiment, the appliance comprises a base having a protective enclosure sealingly engaged therewith. Operative elements of the appliance such as illuminating lamp elements may pass through this base into the area within the protective enclosure. The opposite side of the base is then in communication with the passageway which leads to and through the wall. A small conduit will be provided through this base placing the opposite sides thereof into communication with each other and hence placing the illuminating lamp elements into communication with the passageway and through the latter to the exterior of the chamber. At the wall of the high-pressure chamber, there may be provided a tubular element housing a cylindrical body member through which the gas is adapted to flow, and there may also be provided a needle type control valve at the side of the conduit within the cylindrical body on the outside of the high-pressure chamber wall.  
 BRIE-F DESCRIPTION OF THE DRAWINGS There follows a detailed description of preferred embodiments of the invention to be read together with the accompanying drawings wherein:  
  FIG. 1 is a schematic view of a hyperbaric pressure tight chamber including the features of the present invention.  
  FIG. 2 is an enlarged longitudinal cross-sectional view of a sealed illuminating lamp including features of the present invention.  
 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, like elements are represented by like numerals throughout the two views.  
  FIG. 1 illustrates schematically a hyperbaric, i.e., high-pressure, pressure tight chamber 5 having located therein an apparatus, appliance or the like 10, the interior of which must be maintained at atmospheric pressure for proper operation. For this purpose, the interior of the appliance 10 is connected via line 45 to a cylindrical body 13 located in a wall 12 of the chamber 5, whereby fluid within the appliance 10 may be placed in permanent communication with atmospheric conditions outside of the chamber 5 via elements 45 and 13. If the appliance 10 is an electrical appliance, then the electrical lines shown schematically in FIG. 1 would also pass through elements 13 and 45 to the appliance 10.  
  Referring now to FIG. 2, there is shown a protective enclosure for an appliance generally referred to by the numeral 10 and a member generally referred to by the numeral 11 defining a passage through the wall. The member 1 1 comprises a tube 12a fixed into the wall 12 of the chamber 5 so as to project on either side of said wall. There is further provided within the tube 12a a cylindrical body 13 in which there is provided a longitudinal passageway 14, the axis 15 of which is shifted transversely with respect to the axis 16 of the cylindrical body 13. Electrical cables or the like for the lamp (not shown) would normally be provided within the passageway 14. A pin plug 17 is provided on the outside of the cylindrical body 13. At the end of passageway 14 opposite from the plug 17 there are provided two tubular elements 18, in each of which are inserted the supply cables. The elements 18 open into a cylindrical chamber 19. A cast glass seal 20 is provided on the periphery of the elements 18. The cables would be connected to the elements 18 in a manner known per se.  
  Spaced transversely from the passageway 14 and parallel to the passageway 14 there is provided a conduit 21 which extends for essentially the full length of the body 13 opening at one end into the chamber 19. At the end of this conduit opposite from chamber 19 there is provided threading coaxial with the conduit 21 for receiving a needle valve 22 with a square head, the needle valve cooperating with a conical part 23 of the conduit 21. Surrounding chamber 19 there is provided a band 24 having a seat for receiving a seal 25 which bears against the inner face of the tube 12a and is aligned therewith for this purpose. The part of cylindrical body 13 which projects to the outside of the wall 12 of chamber is threaded for cooperation with a nut locking device 26. Cylindrical body 13 and tube 12a are grooved to receive a key 27 and a nut locking device 28 is disposed between the body 13 and the nut 26 to ensure maintenance of these parts.  
  The band 24 receives a cap 31 fixed to the latter by means of four screws, each cooperating with a threaded opening in the said member 13. This cap 31 includes an annular groove 32 having located therein an O-ring seal 33. It is centered by means of a cylindrical bearing surface 34 which cooperates with the sidewall of chamber 19. The cap 31 is hollow and includes a chamber 35 which is an extension of the chamber 19 of the cylindrical body 13. A flat portion 36 on the exterior of the cap 31 lies in. a plane parallel to the axis of the cap 31 and includes a threaded opening therein for receiving a threaded connection 37 extending perpendicular to the surface 36.  
  The threaded connection 37 is disposed at the end of a tube 45 welded to a hollow connecting piece 46 which is generally conical in configuration. This element 46 at its end has a flange 47. A nut 48 cooperating with the threading of a base 49 ensures fixation of the said base 49 on the flange 47 by virtue of a bearing surface 50 which bears on the flange 47.  
  The base 49 extends to the inside of the connecting piece 46 and intimately cooperates with the same. An O-ring seal 51 disposed in a groove 52 ensures fluid tightness at this location. A plate 55 has mounted thereon an envelope 56. These elements 55 and 56 constitute the operative elements of an illuminating lamp. The plate is carried on the base 49 by means of pins 57 extending from the plate to and through the base 49. The cable means which would extend from the elements 17 to the elements 18 and then from the elements 18 through the tube 45 would connect with these pins 57.  
  Parallel to and coincident with the axis of base 49 there is provided a longitudinal conduit 60 passing through this base from one side to the other, this conduit receiving a calibrated jet or nozzle 61 of reduced cross-section on the side 58 of the base 49 facing into a lamp enclosure 62 which surrounds the operating elements 55 and 56 of the lamp. Preferably, this nozzle 61 is screwed into the end of conduit 60. The lamp enclosure 62 bears at its face 63 against the lateral surface of base 49 where it is held tightly by a band 64. The lamp enclosure 62 includes an external conical part 65 on its outer surface which has thereagainst an annular seal 66 which is disposed between the part 65 and the band 64.  
  With the needle valve 22 in the open position, the volume 67 within the lamp enclosure 62 is connected to atmosphere by means of conduit 21, chambers 19 and 35, tube 45, hollow connecting piece 46, conduit and nozzle 61. This nozzle 61 is of reduced crosssection relative to the cross-section of conduit 60 so as to reduce the maximum possible gas flow therethrough. Thus, if the lamp enclosures 62 should break, the large pressure differential between the interior of the chamber 5 and the surrounding atmosphere could not equalize through the opening forming the passageway because of the limited possibility of airflow therethrough.  
  There has been described a preferred embodiment of the invention in which the appliance within the highpressure chamber is an illuminating lamp. It should be observed, however, that the present invention is applicable for protection of numerous other devices including for example numerous other electronic devices which require pressure insulation. For example, the present invention would be suitable for use with the cathode tube of a television camera.  
  As a modification, the present invention may include two gas flow paths, one introducing air into the protective enclosure and the other removing air therefrom to thereby effect forced venilation of the inside of the protective enclosure. This would be extremely advantageous, for example in situations where considerable heat is generated and this forced flow could remove some of this heat. This would also be useful in other situations wherein the appliance could not tolerate contact with even a very small volume of the gas within the chamber 5. Such a forced venilation system would prevent accumulation of such gases within the protective enclosure.  
  Although the invention has been described in considerable detail with respect to a preferred embodiment, it will be apparent that the invention is capable of numerous modifications and variations apparent to those skilled in the art without departing from the spirit and scope of the invention.  
 What is claimed is:  
  1. In combination, a pressure tight chamber adapted to be filled with a gas at high pressure, an electrical appliance having operative elements within said chamber, said appliance having a protective enclosure encasing and protecting said operative elements of the appliance .from pressure conditions within the pressure tight chamber, and means defining a passageway for placing the interior of the protecitve enclosure containing said operating elements into fluid communication with the exterior of the pressure tight chamber, whereby the interior of the protective enclosure and said operative elements can be kept at atmospheric pressure while the pressure within the pressure tight chamber is increased beyond atmospheric pressure, said means defining a passageway including a nozzle having an opening of reduced cross-section at its end in the protective enclosure for preventing rapid equalization of pressure between the pressure tight chamber and the area external to the pressure tight chamber in the event of breakage of the protective enclosure.  
  2. The invention of claim 1, said appliance being a lamp having a lamp enclosure and a base sealed thereto, said protective enclosure comprising said lamp enclosure and said base said operative elements being electrical elements passing through the base and connected to electrical lines which pass through the passageway to the exterior of the pressure tight chamber, and said passageway including a conduit through the base, the nozzle being fixed onto the end of this conduit facing the lamp enclosure.  
  3. The invention of claim 2, including a cylindrical body passing through the wall of the pressure tight chamber, the passageway including a second conduit passing through the said cylindrical body, and including a control valve at the end of the second conduit outside of the pressure tight chamber wall.  
  4. An electrical appliance adapted to be placed in a pressure tight chamber comprising: operative elements, a base, a protective enclosure sealingly engaged with the base to form a sealed volume enclosing said operative elements of the appliance to protect said operative elements from pressure conditions within the pressure tight chamber, a conduit passing through the base from a first end at a surface thereof within the sealed volume which includes the operative elements of the appliance to a second end at a surface thereof outside of the sealed volume, means defining a fluid passageway from said second end to the exterior of the pressure tight chamber, thereby placing said sealed volume into fluid communication with the exterior of thepressure tight chamber, and including a reduced cross-section nozzle on the first end of the conduit at the sealed volume preventing rapid equalization of pressure between the pressure tight chamber and the area external to the pressure tight chamber in the event of breakage of the protective enclosure.  
  5. An appliance according to claim 4, said appliance being a lamp having a lamp enclosure sealed to said base, said protective enclosure comprising said lamp enclosure and said base said operative elements comprising electrical elements passing through the base and connected to electrical lines which pass through the passageway to the exterior of the pressure tight chamher.  
  6. An appliance according to claim 4, including a cylindrical body adapted to be mounted in the wall of the pressure tight chamber, said passageway including a longitudinal conduit extending through said cylindrical body to the outside of the pressure tight chamber.  
  7. An appliance according to claim 6, including a control needle valve located at the end of the last said conduit on the outside of the pressure tight chamber.  
  8. An appliance according to claim 7, the last said conduit forming a conical surface at its end outside of the pressure tight chamber for receiving the said needle valve.  
  9. In combination, a pressure tight chamber adapted to be filled with a gas at high-pressure, an electrical appliance within said chamber having operative elements and a protective enclosure protecting and enclosing said operative elements of the appliance from pressure conditions within the pressure tight chamber, means defining a passageway for placing the operative elements in the interior of the protective enclosure into fluid communication with the exterior of the pressure tight chamber, whereby the interior of the protective enclosure can be kept at atmospheric pressure while the pressure within the pressure tight chamber is increased beyond atmospheric pressure, a cylindrical body passing through the wall of the pressure tight chamber, the passageway including a second conduit passing through the said cylindrical body, and including a control valve at the end of the second conduit outside of the pressure tight chamber wall.  
  10. An electrical appliance adapted to be placed in a pressure tight chamber comprising: operative elements, a base, said appliance mounted on the base, a protective enclosure sealingly engaged with the base to form a sealed volume and enclosing said operative elements of the appliance to protect the operative elements from pressure conditions within the pressure tight chamber, a conduit passing through the base from a first end at a surface thereof within the sealed volume which includes the appliance to a second end at a surface thereof outside of the sealed volume, means defin ing a fluid passageway from said second end to the exterior of the pressure tight chamber, thereby placing said sealed volume into fluid communication with the exterior of the pressure tight chamber, a cylindrical body adapted to be mounted in the wall of the pressure tight chamber, said passageway including a longitudinal conduit extending through said cylindrical body to the outside of the pressure tight chamber, and including a control needle valve locatedat the end of the last said conduit on the outside of the pressure tight chamber.