Patent Publication Number: US-6335708-B1

Title: Antenna transfer assembly with jam preventing inserts

Description:
The present invention relates in general to the projection and retrieval of an elongated communication antenna. 
     BACKGROUND OF THE INVENTION 
     In association with the present invention, an antenna transfer assembly is provided for exposure to an underwater environment through which a buoyant antenna cable is projected against water pressure or retrieved under selective control through a powered drive mechanism. During deployment of the antenna cable through such an antenna transfer assembly, because of its flexibility forces exerted on the antenna cable when pushed out of a submarine for example against sea water pressure and under friction restraint place it under axial compression causing it to jam. Such jamming occurs because of cable buckling inside of the antenna transfer assembly, preventing further deployment or retrieval movement from being imparted to the cable. It is therefore an important object of the present invention to prevent antenna buckling causing jamming inside of an antenna transfer assembly of a type exposed to an underwater environment, without resort to costly and operationally complex solutions. 
     SUMMARY OF THE INVENTION 
     In accordance with one embodiment of the present invention, a plurality of solid inserts fill empty spaces within which an antenna may otherwise buckle, thus restraining the antenna inside of the intended helical passage formed within the antenna transfer assembly to which the antenna cable is confined while driven under selective control during deployment or retrieval. When the antenna is under axial compression, it cannot buckle between pulleys because of the solid inserts filling up all of the spaces within which buckling may otherwise occur. The solid inserts furthermore supportingly engage the sides of the cable so that cable deployment may continue without buckling or jamming. Such inserts are shaped for disposition adjacent to each other in free-floating positions projecting into the spaces between cable pulleys, instead of being fixed or bolted in place to also allow easy removal and replacement of parts of the assembly during overhaul, including the cable pulleys through which the selectively controlled movement is imparted to the antenna cable. 
    
    
     BRIEF DESCRIPTION OF DRAWING 
     A more complete appreciation of the invention and many of its attendant advantages will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein: 
     FIG. 1 is a perspective view of an antenna transfer assembly with which the present invention is associated, adapted to be mounted on a submarine hull; 
     FIG. 2 is a side elevation view of the antenna transfer assembly illustrated in FIG. 1; 
     FIG. 3 is an enlarged partial section view taken substantially through a plane indicated by section line  3 — 3  in FIG. 2, showing disposition of a cable and jam preventing inserts within the antenna transfer assembly; 
     FIG. 3A is a partial section view, corresponding to that of FIG. 3 without the inserts, and showing the cable jammed in a buckled condition; 
     FIG. 4 is a partial section view taken substantially through a plane indicated by section line  4 — 4  in FIG. 3; 
     FIG. 5 is a partial section view taken substantially through a plane indicated by section line  5 — 5  in FIG. 4; and 
     FIG. 6 is a section view of one of the jam preventing inserts disposed in the antenna transfer assembly taken substantially through a plane indicated by section line  6 — 6  in FIG.  5 . 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
     Referring now to the drawing in detail, FIGS. 1 and 2 illustrate an antenna transfer assembly, generally referred to by reference numeral  10  involving deployment and retrieval of a flexible and buoyant antenna cable  12 , and having an outer cylindrical wall  14  forming a housing closed at its axial ends by end plates  16  and  18 . Extending axially from and attached to the end plate  18  of the housing, is a powered drive assembly  20  enclosed by an outer cylindrical wall  22  of smaller diameter than that of the housing wall  14 . Inlet and outlet guides  23  and  24  are respectively connected to and project tangentially from the cylindrical housing wall  14  for accommodating reception and exit of the antenna cable  12  from the housing within which it is disposed in a helical wound condition as hereinafter pointed out. Such housing of the antenna transfer assembly  10  enclosed by the outer housing wall  14  between the end plates  16  and  18  is placed under high seawater pressure during transport by a submarine hull through an underwater environment. 
     As shown in FIGS. 3,  4  and  5 , the outer housing wall  14  forms an annular passage portion  26  of the housing enclosure formed about a radially inner housing wall  28  within which the inner housing enclosure portion is formed extending into the drive assembly  20 . A pair of bearings  29  and  31  are mounted on the inner housing wall  28  adjacent opposite axial ends thereof for rotational support of a cylindrical drum  33 . The antenna cable  12  is supported on the drum  33  in the aforementioned helically wound condition along a helical path established between rows of circumferentially spaced cable pulleys  30 , such as  24  pulleys  30  disposed within the radially outer portion  26  of the housing enclosure. Each cable pulley  30  is rotationally journaled therein by the housing end plates  16  and  18 , as shown in FIG.  4 . 
     A gear formation  32  at one end of each cable pulley  30  is enmeshed with an annular driving gear  34  fixed to one axial end of the drum  33  through which it transfers rotation simultaneously to all of the pulleys  30  from two of the pulleys  30 . The drive assembly  20  selectively imparts rotation to such two cable pulleys  30  in opposite directions about their axes  36  parallel to the central housing axis  38 . Movement is thereby applied through all of the pulleys  30  to the antenna cable  12  for insertion into and retrieval from the passage portion  26  of the housing enclosure. 
     The two pulleys  30  driven by the drive assembly  20  have axle portions  52  extending therefrom through the end plate  18  as shown in FIG. 4 into the housing  22  of the drive assembly. In addition to rotational support of the axle  52  by a bearing  54 , a seawater seal  56  is provided. The two axles  52  are respectively connected to gears  58  enmeshed with an idler gear  60  supported within the drive assembly housing  22 . The idler gear  60  is in turn enmeshed with a drive gear  62  connected to a hydraulic motor  64  under selective control of the drive assembly  20 , All of the cable pulleys  30  thereby simultaneously driven under control of the drive assembly  20 , have axially spaced curved surface recesses  40  within which the cable  12  is received in its helically wound condition, such as five wraps about the drum  33 . The cable  12  is held in frictional driving contact with each of the pulleys  30  at a plurality of axially spaced locations therealong within their recesses  40  while supported on the drum  33 , is thereby maintained in its helically wound condition extending between the inlet and outlet guides  23  and  24  through the housing passage portion  26  as aforementioned. With the inserted cable  12  so held on the drum  33  by the pulleys  30 , it is deployed under selective control exercised by the powered drive assembly  20 . 
     The antenna cable  12  is pushed out of a hull by the antenna transfer assembly  10  against forces created due to friction and seawater pressure pushing inboard on the antenna tip. Occasionally during such deployment the antenna cable  12  is thereby subjected to high axial compression. Heretofore, such high axial compression caused the antenna cable  12  to buckle, as shown in FIG. 3A, so that buckled sections  12 A of the cable became radially displaced from the drum  33  into the spaces between the cable pulleys  30 . Such buckled sections  12 A of the cable caused jamming which then prevented deployment or retrieval of the cable  12 . Buckling of the cable  12  occurred because of the flexibility property of its construction involving an inner cable wire  42  covered by an outer insulation covering  44  as shown in FIGS. 3,  3 A and  5 . 
     In accordance with the present invention, jamming of the antenna cable  12  by buckling thereof as depicted in FIG. 3A, is prevented by use of free-floating inserts  46  respectively aligned with each of the pulleys  30 , to substantially fill the spaces therebetween and between the pulleys  30  and the outer wall  14  within the radially outer portion  26  of the housing passage enclosure as depicted in FIGS. 3,  4  and  5 . Each of such inserts  46 , as shown in FIGS. 5 and 6, includes an outer curved surface portion  48  from which spaced leg portions  50  extend. The outer insert surface portions  48  almost abut and match the cylindrical inner surface of the stationery outer housing wall  14 . The spaced leg portions  50  of the inserts  46  substantially occupy the circumferential spacings between the recess portions  40  of adjacent pulleys  30 , into which the leg portions  50  of adjacent inserts  46  extend from their outer surface portions  48  which match the closely spaced cylindrical surface of the outer assembly wall  14 . Thus, antenna jamming is avoided by substantially filing otherwise seawater filled spaces with the appropriately shaped inserts  46 , made of solid material and free-floatingly disposed to allow individual insertion and removal of the pulleys  30 , even though they may be occasionally touching the moving surface on the pulleys  30  and/or the internal stationery surface on outer housing wall  14 . 
     Obviously, other modifications and variations of the present invention may be possible in light of the foregoing 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.