Abstract:
A hardened voyage data recorder includes two subsystems: a removable non-volatile memory module and a base containing electronics and firmware for communicating with data sensing systems and for accessing the memory. According to the invention, the memory is a stacked BGA memory protected in a “boiler” which is designed to tolerate a low temperature fire environment for a relatively long term. The boiler and the memory module subsystem are designed to withstand penetration forces associated with marine accidents. Cabling from the memory is arranged so that the structural integrity of the boiler is not compromised.

Description:
[0001]    This application claims the benefit of Provisional Application serial number 60/282,821 filed Apr. 10, 2001, the complete disclosure of which is hereby incorporated by reference herein.  
         [0002]    This application is related to co-pending co-owned application serial number __/___,___ entitled “Hardened Data Voyage Recorder”, filed simultaneously herewith, the complete disclosure of which is hereby incorporated by reference herein. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0003]    1. Field of the Invention  
           [0004]    The invention relates to methods and apparatus for recording data concerning the operation of a sea borne vessel. More particularly, the invention relates to methods and apparatus for recording and protecting data leading up to an accident or “incident”. Further, the invention relates generally to methods and apparatus for protecting heat sensitive items, such as solid state memory devices used in a marine data recorders and the like, from heat that may be produced from fire following a marine accident. The invention also relates generally to methods and apparatus for protecting such items from shock damage and the affects of moisture.  
           [0005]    2. Brief Description of the Prior Art  
           [0006]    It has long been noted that the investigation of maritime accidents and incidents could benefit from the recording of data and audible commands occurring aboard ships. Indeed, many considered this an inevitable technological extension of the time-honored ship&#39;s logbook. This desire has culminated in the development of an international standard governing the performance of a Voyage Data Recorder (VDR).  
           [0007]    In 1974 the Safety of Life at Sea (SOLAS) Convention of the International Maritime Organization (IMO) acknowledged the value and expressed the desire of having recorders on ships similar to the “black box” flight recorders for aircraft. This began a long process of establishing international standards and requirements for a Voyage Data Recorder (VDR).  
           [0008]    In 1996, VDR requirements, which had been debated for a long time, began to emerge in the navigation and electronics subgroup (NAV) of the IMO. Anticipating an eventual IMO resolution concerning VDRs, IEC (International Electrotechnical Commission) TC80 formed WG11, which began structuring a specification based on preliminary drafts of the NAV requirements. The IMO passed resolution A.861 (20) in November 1997 and the IEC standard 61996 was completed as a Committee Draft for Voting in March 1999. The specification was published in August 2000.  
           [0009]    The IEC 61996 Ship Borne Voyage Data Recorder Performance Requirements describes data acquisition and storage functions and refers to a “protective capsule” and a “final storage medium”. Architecture for complying with this standard has emerged with two major components.  
           [0010]    In the first component, the ship&#39;s interfaces, data acquisition, and soft recording functions are encompassed in a Data Management Unit (DMU). The DMU is intended for installation in the relatively benign environment of the bridge. The second component is the Hardened Voyage Recorder (HVR) which encompasses the protective capsule and final storage medium. The HVR is designed for survivability and recoverability. It is intended for external installation on the bridge deck or on top of the superstructure.  
           [0011]    The primary function of the Hardened Voyage Recorder (HVR) is to protect the data acquired by the Voyage Data Recorder (VDR) so that the data can be used during accident or “incident” investigation.  
           [0012]    Previously incorporated co-owned co-pending serial number __/___,___ discloses details related to the electronics and software of the HVR. The present application relates to the physical details of the “protective capsule” containing memory. The protective capsule must protect the memory from impact damage, thermal damage and moisture damage.  
           [0013]    It is known in the art of aircraft flight recorders to use a “boiler” to protect memory from thermal damage. A “boiler” is defined herein as a multiple (two or more) compartment containment structure which may be used to separate a thermal mass (such as water) from devices (such as solid state memory devices) being protected.  
           [0014]    U.S. Pat. No. 5,750,925, entitled “Flight Crash Survivable Storage Unit With Boiler For Flight Recorder Memory”, issued May 12, 1998, originally assigned to Loral Fairchild, Corp. (Purdom et al.), the complete disclosure of which is incorporated herein by reference, describes one such “boiler”. More particularly, the &#39;925 patent describes a unit designed to withstand temperatures of 1100 degrees C (approximately 2000 degrees F), which is defined herein to be a “high temperature” environment for a relatively short term.  
           [0015]    Although the unit described in the &#39;925 patent is suitable for protecting heat sensitive components (like solid state memory) in a high temperature environment, such as the environment that often accompanies aircraft fires; problems germane to the survivability of heat sensitive components following a marine crash are very different from those arising following an air disaster and are not addressed by Purdom et al., or indeed any known marine recorders.  
           [0016]    In particular, marine recorders need to be able to survive in “low temperature” fires, i.e., a fire defined herein to be burning (or smoldering) at 260 degrees C for a relatively long term, e.g. 10 hours, as opposed to aircraft recorder high temperature industry survivability specifications of being able to withstand an 1100 degree C environment for 1 hour.  
           [0017]    Low temperature fires were not a problem with prior art protective units, such as the one described in the incorporated &#39;925 patent, because those units used “TSOP” (thin small outline package) memory components, with leads extending therefrom. As a result, even if a board could not (or did not) survive a low temperature fire, the memory chips that did survive and could be “reworked”, i.e., be placed on another board easily and read.  
           [0018]    In the present application (marine recorder application) low temperature fire survivability at the board level becomes very important since it is desirable to use “BGA” (ball grid array) packages for memory components. These smaller packages can be more densely packed, use less “real estate”, etc.; but suffer from the constraint that connections are made under the device. I.e., no leads extend out from the periphery of a BGA package (like they do from a TSOP) which could make board reworking after a low temperature fire difficult or impossible. Nevertheless, the BGA design is otherwise desirable for the reasons indicated hereinabove and for other reasons described below.  
           [0019]    For example, it is further desirable to use BGA packaging since the spacing between connections is larger than with TSOP. This fact enhances unit reliability since it is easier to prevent solder bridges. In addition to a more reliable unit, a unit utilizing BGA memory is easier to fabricate.  
           [0020]    Thus, even though no leads extend therefrom and it is more difficult (or impossible) to rework a memory storage unit if a board is destroyed in low temperature fire, it is nevertheless desirable to provide and protect (in the marine context) BGA memory, i.e., provide a boiler protected BGA solid state memory that can survive a low temperature fire at board level over relatively long term.  
           [0021]    Further, using the &#39;925 patent as a frame of reference, the boiler described in that patent does not provide the mechanical strength required for marine applications. More particularly, marine applications standards addressing “penetration” are different from those for flight recorders since the size of objects involved in a marine accident are typically considerably larger than the relative light weight pieces of an aircraft involved in an air crash.  
           [0022]    As a result, energy is not absorbed by the penetrator (penetrating object) breaking up. Since the objects, such as ship components or ships themselves, are relatively larger and heavier (compared with aircraft parts), and all of a penetrator&#39;s energy could be directed towards the boiler, structural considerations for using a boiler in the marine context is a serious new problem that did not exist in the flight recorder context. The shape, structure and materials used for a marine boiler becomes an issue if the boiler is to survive and perform its protective function.  
           [0023]    Further problems exhibited by prior art boilers, including the one described in the &#39;925 patent, limit their suitability for use in marine applications. In particular, the cabling exiting design used in connection with such boilers is not acceptable for marine applications. This is because it impacts the structural integrity of the boiler itself rendering it unsuitable for the marine environment.  
           [0024]    It may be seen with reference to the &#39;925 patent that the cable exits the boiler via a rectangle cut out of plate edge; this is a point of weakness in the lid.  
         SUMMARY OF THE INVENTION  
         [0025]    It is therefore an object of the invention to provide a Hardened Voyage Recorder which meets or exceeds the requirements of the IEC 61996 test specifications.  
           [0026]    It is also an object of the invention to provide a Hardened Voyage Recorder which incorporates a memory unit protected in a boiler.  
           [0027]    It is another object of the invention to provide a Hardened Voyage Recorder which includes a boiler which is capable of withstanding a low temperature fire for a relatively long term.  
           [0028]    It is yet another object of the invention to provide a Hardened Voyage Recorder which utilizes BGA memory.  
           [0029]    It is another object of the invention to provide a Hardened Voyage Recorder which includes a boiler with improved cable routing such that the integrity of the boiler is not compromised.  
           [0030]    It is still another object of the invention to provide a Hardened Voyage Recorder which includes a boiler having an improved cover.  
           [0031]    It is yet another object of the invention to provide a Hardened Voyage Recorder which includes a stacked memory protected by a boiler.  
           [0032]    In accord with these objects which will be discussed in detail below, the Hardened Voyage Recorder (HVR) according to the invention includes two separable subassemblies. The first subassembly is a mounting base subassembly designed to be directly fastened to the ship and provide a watertight cable entry for power and data connections. The second subassembly is a removable hardened memory subassembly which is attached to the mounting base with a quick releasing clamp.  
           [0033]    The hardened memory subassembly has a bracket for an externally mounted underwater location beacon with dual activation moisture sensors to avoid inadvertent activation due to spray, rain, or hosing off. The HVR is preferably painted a highly visible florescent orange with white reflective labels. The reflective labels contain the required text: VOYAGE DATA RECORDER, DO NOT OPEN, REPORT TO AUTHORITIES.  
           [0034]    The mounting base subassembly includes electronics for receiving data and writing data to the memory in the hardened memory subassembly as disclosed in more detail in previously incorporated serial number __/___,___ filed simultaneously herewith.  
           [0035]    The removable hardened memory subassembly preferably includes 1.5 gigabytes of BGA solid state memory arranged in a stack which is protected in a boiler. According to the presently preferred embodiment, the hardened memory subassembly includes a substantially cylindrical stainless steel “bell” containing a substantial layer of insulation defining a cylindrical well for receiving the boiler.  
           [0036]    The boiler according to the invention includes a bifurcated cylindrical member, one portion of which is a thermal expansion cavity adapted to contain a phase change material or “thermal mass” which acts as a heat sink. The other portion of the bifurcated cylindrical member defines a storage compartment for a stacked memory.  
           [0037]    According to the presently preferred embodiment, a ribbon cable extends from the last memory board in the stack and through a circular opening spaced away from the edge of a stainless steel cover. The boiler is disposed in the cylindrical well defined by the insulation in the bell. A silicone rubber pad is placed over the ribbon cable to protect it an a cylindrical insulator is placed in the cylindrical well to fill it. A stainless steel cover used to hold insulation and the boiler into the bell is locked into the bell by two snap rings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0038]    [0038]FIG. 1 is a perspective view of an HVR according to the invention;  
         [0039]    [0039]FIG. 2 is a side elevation view of an HVR according to the invention;  
         [0040]    [0040]FIG. 3 is a side elevation view of the hardened memory subassembly with the beacon bracket removed;  
         [0041]    [0041]FIG. 4 is a sectional view taken along line A-A in FIG. 3;  
         [0042]    [0042]FIG. 5 is an exploded perspective view of a boiler according to the invention;  
         [0043]    [0043]FIG. 6 is a plan view of the assembled boiler showing the ribbon cable;  
         [0044]    [0044]FIG. 7 is a side elevational view in partial section of the assembled boiler; and  
         [0045]    [0045]FIG. 8 is an enlarged detail of the circled portion of FIG. 7. 
     
    
     DETAILED DESCRIPTION  
       [0046]    Turning now to FIGS.  1 - 3 , the Hardened Voyage Recorder (HVR)  10  according to the invention includes two separable subassemblies. The first subassembly  12  is a mounting base subassembly designed to be directly fastened to the ship and provide a watertight cable entry for power and data connections. The second subassembly  14  is a removable hardened memory subassembly which is attached to the mounting base with a quick releasing clamp.  
         [0047]    Referring now to the mechanical features of the subassembly  12 , as shown in FIGS. 1 and 2, the mounting bas e subassembly  12  has a lower flange  16  defining three mounting holes  18 ,  20 ,  22 . Two cable gland connectors  24 ,  26  are provided for a watertight coup ling of power and data cables (not shown). As seen best in FIG. 2, the subassembly  12  is also provided with an upper flange  28  which is used to provide a sealing engagement with the removable hardened memory subassembly  14 .  
         [0048]    The mechanical features of the hardened memory subassembly  14  include a bracket  38  for an externally mounted underwater location beacon  40 . The beacon is preferably provided with dual activation moisture sensors to avoid inadvertent activation due to spray, rain, or hosing off. The subassembly  14  also has two lifting handles  42 ,  44  and a lower flange  46  which is used to provide a sealing engagement with the subassembly.  
         [0049]    The HVR also includes a V-band  48  having two quick release clamps  50 ,  52 . As mentioned above, the HVR is preferably painted a highly visible florescent orange with white reflective labels, e.g. label  54  shown in FIGS. 1 and 2. The reflective labels contain the required (by IEC 61996) text: VOYAGE DATA RECORDER, DO NOT OPEN, REPORT TO AUTHORITIES. A strip of reflective tape,  19 , is shown in FIG. 1, further satisfying the requirements of IEC 61996.  
         [0050]    The presently preferred embodiment of the HVR  10  is approximately thirteen inches high and has a diameter of approximately eight inches. The lower flange  16  of the subassembly  12  is substantially triangular and is approximately ten inches per side. The total weight of the HVR is approximately forty one pounds with the base  12  weighing approximately thirteen pounds and the memory subassembly  14  weighing approximately twenty eight pounds.  
         [0051]    As shown in FIG. 4, the subassembly  14  generally includes memory  56  which is protected in a boiler  58 .  
         [0052]    More particularly, the subassembly  14  includes a stainless steel bell  60  which is preferably cylindrical in shape and which defines a first interior cylindrical space  62 . A first insulating member  64  is disposed in the cylindrical space  62  and defines a second interior cylindrical space  66 .  
         [0053]    As seen in FIG. 4, the cylindrical space  66  has a stepped configuration. The boiler  58  containing the memory  56  is disposed in the cylindrical space  66 . A second insulating member  68  is placed in the cylindrical space  66  covering the boiler  58  and the step of the space  66 . The bell  60  is sealed with a stainless steel disk  70  which is held in place by inner and outer snap rings, not shown.  
         [0054]    Turning now to FIGS.  5 - 8 , the boiler  58  according to the invention includes a bifurcated cylindrical member  80 , one portion of which is a thermal expansion cavity  82  (seen best in FIG. 7) adapted to contain a phase change material or “thermal mass” (not shown) which acts as a heat sink. The other portion  84  of the bifurcated cylindrical member  80  defines a storage compartment for a stacked memory  56 . The two portions  82  and  84  are separated by a demising wall  83 . The demising wall  83  includes a fusible valve  85  which opens at a predetermined temperature to allow the thermal mass to enter the compartment  84  and protect the memory from fire.  
         [0055]    Suitable compounds for use as a thermal mass include water and wax which are both phase change materials. However, the thermal mass need not be a phase change material. It need only be capable of acting as a heat sink. According to a one embodiment of the invention, water is contained in a dry material which inhibits the water from freezing or expanding. Such materials include (for example) sponge, silica, polyacrylamide, calcium silicate or pottery clay. It should be noted that containment compartment  82  for containing a thermal mass may include the a thermal expansion cavity to accommodate expansion of the thermal mass.  
         [0056]    Another acceptable thermal mass is a dry powder thermal mass formed by combining water and silica, or a gel formed by combining water and polyacrylamide. The thermal mass created from such compositions inherently absorb shock which provides additional protection for the memory  56  contained in the boiler  80 .  
         [0057]    According to the presently preferred embodiment, the memory  56  includes three circuit boards  86 ,  88 ,  90 , each having an electrical coupling  87 ,  89 ,  91 . Each circuit board preferable provides  512  megabytes of memory assembled from four 128 megabyte BGA memory chips or from sixteen 32 megabyte BGA memory chips (not shown). The total volume of the memory  56  is therefore preferably 1.5 gigabytes. As mentioned in the previously incorporated related application, the memory boards may be advantageously provided with MIC chips to address the memory.  
         [0058]    Each memory board is provided with four peripheral mounting holes  92 ,  94 ,  96 ,  98 ;  100 ,  102 ,  104 ,  106 ; and  108 ,  110 ,  112 ,  114 . The three memory boards  86 ,  88 ,  90  are assembled with four screws  116 ,  118 ,  120 ,  122 , four nylon nuts (only three of which are seen in FIG. 5)  124 ,  126 ,  128  and eight spacers (only six of which are seen in FIG. 5)  130 ,  132 ,  134 ,  136 ,  138 ,  140 .  
         [0059]    Each of the four screws  116 ,  118 ,  120 ,  120  has a threaded head as seen best with regard to screw  122  in FIG. 8. A cover plate  142  having four peripheral mounting holes  144 ,  146 ,  148 ,  150  is fastened to the threaded heads of the screws  116 ,  118 ,  120 ,  120  by four short screws  152 ,  154 ,  156 ,  158 . As seen in FIG. 8, the board to board connectors have a female part on one side of the board and a male part on the other side of the board, thereby permitting any number to be stacked. Accordingly, the connector  91  immediately adjacent to the cover plate  142  is insulated from the cover plate by a piece of tape  160 . According to a presently preferred embodiment, the cover plate  142  is press fit into the boiler  80  as seen best in FIG. 8.  
         [0060]    According to the presently preferred embodiment, a ribbon cable  162  is hard wired to the last memory board  90  as seen best in FIG. 8. The ribbon cable  162  is preferably provided with a J 10  connector  164  for coupling to electronics in the base assembly as described in more detail in the previously incorporated related application filed simultaneously herewith.  
         [0061]    According to the presently preferred embodiment, the cover plate  142  is provided with a circular opening  166  which is spaced apart from the edge of the plate. The ribbon cable  162  passes through the opening  166 .  
         [0062]    As shown in the Figures, and in particular FIG. 4, the cable  162  follows a path through six bends. These bends allow the cable to exit the boiler, route between the two insulators  64 ,  68  (FIG. 4), exit the bell  60  through an opening  71  in the stainless steel disk  70 , move across the bottom of the bell and go down to the electronics subassembly ( 12  in FIG. 2. In order to relieve stress at the exit opening  71 , a cable guide  73  is provided adjacent thereto.  
         [0063]    As seen best in FIG. 4, the arrangement of the ribbon cable is such that it need not traverse as much insulation as the cable in the prior art boilers such as the aforementioned &#39;925 patent. According to the invention, the cable is further protected by a silicone rubber pad which is placed between the cable and the insulation.  
         [0064]    The removable memory subassembly according to the invention withstands a penetration of a 100 mm 250 kg projectile at three meters. It will withstand a 50 g&#39;s, 11 ms half sine shock and an immersion of 6,000 meters depth. The memory will withstand a 260° C. fire for ten hours.  
         [0065]    There have been described and illustrated herein a hardened voyage data recorder, a removable memory module assembly, and a boiler for protecting the memory therein. While particular embodiments of the invention have been described, it is not intended that the invention be limited thereto, as it is intended that the invention be as broad in scope as the art will allow and that the specification be read likewise. It will therefore be appreciated by those skilled in the art that certain modifications could be made to the provided invention without deviating from its spirit and scope as so claimed.