Abstract:
A power delivery system for parked aircraft includes protective rings on the power cords. These protective rings protect the power cord jackets from wear and facilitate movement of the power cords across the ground. The rings may be configured for securement to the cable so as to compress the insulative jacket of the cable somewhat, thereby firmly maintaining the rings in place on the cable. The rings may be formed of two identical elements that are joined to envelope the cable. The rings may accommodate both round insulated cable, as well as bundled cable.

Description:
BACKGROUND 
   This invention relates generally to aircraft power delivery systems. More particularly, the invention relates to a technique for protecting cables and cable assemblies, and for facilitating movement of such cables across pavement at a terminal or other location at which aircraft may be parked. 
   Most aircraft have multiple power delivery systems which are used during different periods of operation. That is, electrical systems of an aircraft that is flying or taxiing on a runway are powered by an auxiliary power unit (APU) which typically includes an internal engine coupled to a generator or alternator, much as in a car. On the other hand, an aircraft that is parked is generally powered by an external power source. These external sources can be mobile generator systems or power units built into a terminal, passenger boarding bridge, or hangar. 
   To supply power to a parked aircraft from an external power source, the aircraft must essentially be plugged into the power unit. As with most devices that must be plugged in for power, the aircraft is connected to the power supply unit via a power cord or cable. The cable or cable assembly is generally selected based upon the voltage and current requirements. By way of example, an industry standard has been developed for certain aircraft power cables to supply power at a rated 260 amps and 400 Hz. 
   As can be expected, power cords used to plug in an aircraft are significantly larger than a standard household power cable. For example, these cables can have outer diameters on the order of 1 to 2 inches. Alternatively, some of these power cords can actually include several smaller cables bundled together. In addition, because the aircraft cannot always be brought into close proximity with the external power supply units, some cables must be quite long. In the case of commercial aircraft, these cables generally must stretch from a loading gate, or other location where the plane is parked, across the tarmac to the terminal building, where the power supply unit is located, or to a mobile power supply. 
   It can be appreciated that these cables, due to their length and thickness, are often quite heavy. For example, a 260 amp, 400 Hz cable of the type mentioned above, that is 60 feet long, can weigh in excess of 130 pounds. Operators must move these cables across the paved surfaces of the tarmac and runways to stretch the cables from the power supply units to the aircraft. Dragging a long, heavy cable across paved surfaces can be quite difficult and inevitably leads to wear and degradation of the cable insulating jacket. 
   One solution to facilitate movement of the cables across paved surfaces has been to coat the cables with a slick insulating jacket. This slick coating enables the cables to slide more easily across the tarmac and runways. However, this solution does not address the problem of wear on the cables, and over time degradation of the slick insulating jacket makes even these cables very difficult to maneuver. 
   Therefore, it would be advantageous to have a system that allows for easy maneuverability of aircraft power cables across paved surfaces while also protecting the insulating jackets of the cables from wear. 
   BRIEF DESCRIPTION 
   In accordance with an exemplary embodiment of the present invention, protective rings are coupled to a cable assembly for supplying power to a parked aircraft. The rings are designed to facilitate movement of the cable assembly across the ground. As such, the rings are compressively secured to the cable assembly such that each ring remains at roughly its original location relative to the cable assembly. Each ring may be made of two generally identical halves, thereby reducing set-up and production time and cost. The ring halves are secured together by a locking mechanism, several embodiments of which are described below. 
   In accordance with an additional embodiment of the present invention, the protective rings are configured to be coupled to a bundled cable assembly. This type of cable assembly is an alternative to the single cable assembly. 

   
     DRAWINGS 
     These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
       FIG. 1  is a diagrammatical view of an aircraft connected to a power supply unit via a power cable assembly with protective rings, according to an embodiment of the present invention; 
       FIG. 2  is a perspective view of a power cable assembly with rings of the type shown in  FIG. 1 ; 
       FIG. 3  is a somewhat more detailed perspective view of the power cable assembly of  FIG. 2 ; 
       FIG. 4  is a perspective view of one segment of the ring in  FIG. 3 ; 
       FIG. 5  is a cross-sectional view of the ring in  FIG. 3 , taken along line  5 - 5 ; 
       FIG. 6  is a perspective view of a power cable assembly and one segment of a protective ring according to an embodiment of the present invention; 
       FIG. 7  is a perspective view of a power cable assembly and segment of an alternative protective ring design; 
       FIG. 8  is a perspective view of a power cable assembly and segment of another alternative protective ring design; 
       FIG. 9  is a perspective view of a power cable assembly and segment of a further alternative protective ring design; 
       FIG. 10  is a perspective view of one segment of a further alternative protective ring, for use with multi-cable assemblies; 
       FIG. 11  is a perspective view of a segment of a bundled multi-cable power cable assembly with a protective ring of the type shown in  FIG. 10 ; 
       FIG. 12  is a prospective view of one segment of another alternative protective ring, similar to that of  FIG. 10 , but for use with a multi-cable assembly including a pair of cables; and 
       FIG. 13  is a prospective view of a segment of a bundled multi-power cable assembly installed in a protective ring of the type shown in  FIG. 12 . 
   

   DETAILED DESCRIPTION 
   Referring generally to  FIG. 1 , a parked aircraft power delivery system is illustrated, generally designated by the reference numeral  10 . An aircraft  12 , which may be a commercial, military or private aircraft, is illustrated as it may be parked on the ground  14 , such as at a terminal or other facility. Ground  14  is generally a tarmac, runway or hangar floor, but could be any surface on which an aircraft is parked. The aircraft  12  is connected to a power supply unit  16  by a cable assembly  18 . As will be appreciated by those skilled in the art, the power supply unit  16  may be a mobile unit (e.g., an engine-driven generator set), or may be fixed in position (e.g., drawing power from the grid). In either case, the cable assembly  18  delivers power for operation of various systems of the aircraft to alleviate the need to draw upon the onboard power generation resources of the aircraft itself. 
   Cable assembly  18  must be moved out of the way of aircraft  12  when aircraft  12  is in motion, such as when it taxies to and from a terminal. When aircraft  12  is parked, cable assembly  18  is moved into proximity and plugged into aircraft  12 , thus completing an electrical connection between the power supply unit  16  and aircraft  12 . Before aircraft  12  begins moving, cable assembly  18  is unplugged from aircraft  12  and moved away so that it is not in the path of aircraft  12  or so that it can be used to couple power supply unit  16  to another aircraft. As discussed above, a standard 260 amp, 400 Hz cable assembly with an outer diameter of 1.65 inches can weigh over 130 pounds, and cable assemblies can be longer and/or thicker than this standard. 
   Protective rings  20  are coupled to the cable assembly  18  to facilitate moving the cable assembly across the ground, such as by sliding. The rings also prevent or reduce wear on the cable due to abrasion by the ground surface. In the implementation shown in  FIG. 1 , the rings are spaced at 1 to 2 foot intervals along the cable assembly, although other spacings may be used. Exemplary embodiments of protective rings  20  are illustrated in  FIGS. 4 and 5  and discussed below. In addition, alternative embodiments of protective rings  20  are illustrated in  FIGS. 6-11 . 
   As further illustrated in  FIGS. 2 and 3 , protective rings  20  are coupled to a segment of cable assembly  18 . In the illustrated embodiment, each protective ring  20  is made up of a first half  22  and a second half  24 . The outer periphery  26  of each ring is configured to bear against a support surface, such as the ground  14 , and to slide along the ground  14  during movement of the cable assembly by service personnel. As described in greater detail below, the inner periphery  28  of each ring is configured to bear against and compress an outer insulative jacket  30  of the cable assembly  18 . The halves  22 ,  24  of the rings are secured together at joint  32 . A recess  34  in the outer periphery  26  of each half  22 ,  24  provides access to the locking member  44 , discussed in detail in reference to  FIGS. 4 and 5   
   In certain presently contemplated embodiments, half  22  and half  24  are identical to one another, and are designed such that inversion of half  24  relative to half  22  disposes mating elements in a mutually facing relation. Joining the halves, then, forms a complete protective ring  20 . Certain possible arrangements for coupling together of the halves are discussed in detail in reference to  FIGS. 4 and 5 . 
   Referring to  FIG. 4 , half  22  of protective ring  20  is shown, according to a presently contemplated embodiment. As discussed above, half  24  is identical to half  22 . Each half may be formed by any suitable process, such as injection molding using a plastic, for instance glass-reinforced nylon. Because halves  22 ,  24  are identical, only one injection molding die must be created for each ring produced, thereby reducing the set-up costs generally associated with manufacture of the rings. In addition, production costs are minimized because any two halves may be packaged together to form a complete ring. That is to say, it is not necessary to ensure that two different parts of a ring are packaged together because any two parts produced are sufficient to create a ring. 
   Half  22  includes a front face  36 , and a rear face  38  arranged substantially parallel to front face  36 , configured to support the structure of half  22 . In addition, the junctions of the front face  36  and rear face  38  with the outer periphery  26  may be generally rounded to facilitate movement of protective ring  20  as cable assembly  18  is slid along the ground  14  in a direction generally perpendicular to faces  36 ,  38 . Inner periphery  28  includes both protruding ribs  40  and reinforcing ribs  42 . It is generally desirable that protective rings  20  remain stationary relative to cable assembly  18  as the cable assembly  18  moves across the ground  14 . Accordingly, when halves  22 ,  24  are placed around cable assembly  18  and secured together, as discussed below, protruding ribs  40  may compress the outer insulative jacket  30  of the cable assembly  18 . The protruding ribs  40  are preferably configured such that they secure protective ring  20  to the cable assembly  18  at the attachment location, thus preventing protective ring  20  from sliding along the length of cable assembly  18 . Reinforcing ribs  42  are configured to support the structure of half  22 . One skilled in the art will appreciate that these reinforcing ribs could also be designed to compressively secure the protective ring to a cable assembly as the protruding ribs  40  are designed to do. 
     FIGS. 4 and 5  illustrate an exemplary contemplated mechanism for coupling together halves  22 ,  24 . In this embodiment, half  24  is inverted relative to half  22 . A locking member  44  comprises a cam surface  46 , configured to resiliently deflect locking member  44  upon insertion into engagement opening  50  past a locking surface  48 . Surface  48  is configured to prevent removal of locking member  44  from engagement opening  50 . Engagement opening  50  comprises an outer edge, configured to resiliently deflect locking member  44  upon contact with cam surface  46 , and an abutment surface  56 , configured to prevent removal of locking member  44  from engagement opening  50 . Recess  34  is configured to provide access to the locking member  44 . 
   The halves  22 ,  24  are assembled as follows. Upon inversion, tabs  52  are aligned with recesses  54 . These tabs  52  and recesses  54  are configured to aid in proper alignment of halves  22 ,  24  and to provide additional support to the protective ring  20  at the joint  32 . When half  22  is placed adjacent to inverted half  24 , cam surface  46  comes into contact with the edge of engagement opening  50 . As halves  22 ,  24  move together, the pressure exerted by engagement opening  50  on cam surface  46  causes locking member  44  to deflect. Once cam surface  46  moves entirely past abutment surface  56  inside engagement opening  50 , locking member  44  returns to roughly its original position. Locking surface  48  then rests in contact with abutment surface  56 , thereby preventing removal of locking member  44  from engagement opening  50 . 
   Halves  22 ,  24  may be uncoupled by resilient deflection of locking member  44 . Recess  34 , accessible on outer periphery  26 , is configured to allow for contact with cam surface  46 . Depression of cam surface  46  may resiliently deflect locking member  44  such that locking surface  48  and abutment surface  56  are no longer in contact. By deflecting locking member  44  enough that locking surface  48  is entirely disengaged from locking surface  56 , locking member  44  may be removed from engagement opening  50 . Upon separation of halves  22 ,  24 , both halves return to generally their original formations. 
   Referring generally to  FIGS. 6-9 , alternative embodiments of half  22  are shown with power cable assembly  18 . These alternative embodiments of half  22  have substantially similar structural features to those discussed above. Various possible locking mechanisms are illustrated.  FIG. 6  is an illustration of half  22  with a resiliently deflective locking member  44 , as discussed above in reference to  FIGS. 4 and 5 . 
     FIG. 7  illustrates an alternative embodiment of the present invention, wherein halves  22 ,  24  are coupled together by a bolt  60  and nut  62 . In this embodiment, halves  22 ,  24  are aligned by tabs  52  and recesses  54  as discussed above. Aperture  58  on both ends of half  22  is configured to receive bolt  60 . Bolt  60  may be secured in place by nut  62 . 
     FIG. 8  illustrates a further alternative embodiment of half  22 . In this embodiment, half  22  includes a central recess  64  configured to receive a band  66 . Halves  22 ,  24  are coupled together by band  66 . Band  66  may include a worm clamp, band clamp or other roughly circular fastener, as will be appreciated by one skilled in the art. 
     FIG. 9  is yet another illustration of an alternative embodiment of half  22 . In this embodiment, half  22  comprises a locking protrusion  68  configured to receive a roll pin  70 . Halves  22 ,  24  are secured together when roll pin  70  is inserted into locking protrusion  68 . 
   Referring generally to  FIGS. 10 and 11 , a further embodiment of the present invention is shown. The outer features and locking mechanism of this embodiment are similar to those discussed in relation to the embodiment shown in  FIGS. 4 and 5 . In this embodiment, protective ring  20  is configured to be coupled to a bundled cable assembly  76 . As those skilled in the art will appreciate, a standard bundled cable assembly  76  for supplying power to a parked aircraft  12  may comprise four individually insulated cable segments surrounding a smaller cable segment. As illustrated in  FIG. 10 , inner periphery  28  may have a roughly scalloped or lobed shape configured to conform to the shape of bundled cable assembly  76 . The roughly scalloped shape of inner periphery  28  may include a full recess  74 , configured to receive an entire segment of bundled cable assembly  76 , and two partial recesses  72 , each configured to receive half a segment of bundled cable assembly  76 . As described above in reference to  FIGS. 4 and 5 , the protruding ribs  40  of inner periphery  28  may be configured to compress the insulative jackets of the segments of bundled cable assembly  76  such that protective rings  20  do not slide freely along bundled cable assembly  76 . In addition, any of the locking mechanisms described above may be used to couple together halves  22 ,  24  according to the present embodiment. 
   Referring now to  FIGS. 12 and 13 , a different embodiment of the protective  20  is illustrated. The half-ring shown in  FIG. 12  is essentially similar to that shown in  FIG. 10  above. However, the ring of  FIGS. 12 and 13  is intended to accommodate a two-cable bundle. Accordingly, two partial recesses  72  form the inner periphery  28  of each ring so as to contact and slightly compress the isolative jackets of the two cables located therein. Rings of the type illustrated in  FIGS. 12 and 13  are particularly well-suited for cable assemblies destined for providing direct current power to applications. It should be noted that while multiple and two-cable assembly protective rings are shown in  FIGS. 10 ,  11 ,  12  and  13 , other configurations may certainly be envisaged that accommodate a different number of individual cables in a bundle or assembly, or that arrange the individual cables of the bundle in different patterns. 
   While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.