Abstract:
Systems and methods are disclosed for stabilizing a wire, cable ( 10 ), line, or cord system. The present invention involves systems that allow a cable ( 10 ), such as a power line cable ( 10 ) and the insulator strings ( 20 ), the ability to extend during loading conditions and to regain their previous geometry once loads, such as ice loads, have been shed. The present invention may be utilized in a number of applications, including but not limited to, being used with anchor, angle, and dead-end structures and with suspension structures to counterbalance loads on cables ( 10 ) and supports included by ice and wind. A combination of suspension structure with anchor structure and the present invention may, on any given section of a cable ( 10 ), result in uniformity of supports and in reduction of their weight and cost, in addition to providing reliability.

Description:
This application is a U.S. National Stage Filing under 35 U.S.C. 371 from International Application Number PCT/US2006/043814, filed Nov. 9, 2006, and published in English as WO 2007/056581 A2 on May 18, 2007, which claims priority under 35 U.S.C. 119(e) to U.S. Provisional Application Ser. No. 60/734,936, filed Nov. 9, 2005, which applications and publication are incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The present invention relates generally to the field of wire, cable, lines, or cord management, and more particularly to systems and methods for stabilizing wire, cable, line, or cord systems under heavy or variable loading conditions. 
     2. Background of the Invention 
     Cabling today is ubiquitous. As the number of applications and appliances that require some form of cable or wire connections increases, so does the amount of cabling. Such cabling may consists of electrical cabling to supply power to a device, a home, or an office. Cabling may also be used for data communication, such as, for example, wires for cable television, telephone lines, Internet access lines, and fiber optic cabling. 
     As society becomes ever more reliant on the services provided by cabling, whether it is simply providing power or providing some service such as telephone access, it becomes even more important that cabling systems be protected from failures. Failures in the cabling can occur as a result of stresses on the cabling. The stresses may result from mechanical or thermal changes. These failures are particularly more prevalent in cabling that resides in outdoor environments. Loading on the cable may occur due to strong winds or due to snow, ice, trees, or other items falling or resting on the cable. 
     Consider, by way of example, problems that occur for cables, such as power lines and telephone lines during ice storms. During ice storms, it is not uncommon that the accumulation of ice on such lines increases the tension in those lines to the point at which the lines break or the supporting structures upholding those lines collapse, leaving many people without electricity or telephone access. Not only do such broken lines deprive individuals of essential services, but finding and repairing those broken lines is time consuming and costly. 
     Prior solutions to dealing with increased loading on cables caused by abnormal weather conditions have focused on making the supporting structures heavier and more rigid. Unfortunately, in many cases that has not been sufficient to prevent the collapse of long sections of cables, resulting in catastrophic consequences to consumers and to suppliers. Conditions causing such failures can, nonetheless, be expected to arise anew, year after year. 
     Accordingly, what is needed are improved systems and methods of stabilizing wire, cable, line, or cord systems to withstand greater variations in loading. 
     SUMMARY OF THE INVENTION 
     According to an aspect of the present invention, systems and methods are disclosed for stabilizing wire, cable, line, or cord systems and their supports to withstand greater variations in loading. As used herein, the terms “cable” shall be construed to include, and may be used interchangeably with, the terms wire, cabling, line, cord, and the like. 
     An aspect of embodiments of the present invention is the replacement of rigidity, bulk, and weight, as used in prior solutions, with flexibility and adaptability by letting the sag of a cable increase between support structures in response to any load increases, and then by letting the cable regain its previous geometry, once these loads have subsided. 
     Exemplary embodiments of the present invention involve systems that impart to a cable the ability to extend during loading conditions and to regain its previous geometry once loads, such as ice loads, have been shed. The present invention may be utilized in any situation in which a cable, line, or cord may be subjected to variable loading conditions. Exemplary applications of the present invention include, but are not limited to, use of the present invention with anchor, angle, and dead-end structures and with suspension structures to counterbalance abnormal loads on cables and supports induced by ice and wind. In one embodiment, the use of teachings of the present invention will, in addition to improving reliability, contribute to the development of more uniform strains levels in those support structures, thereby leading to reductions in the weight and cost associated with the support structures. 
     In one aspect of the present invention, a system is provided for stabilizing a cable upheld by a support structure during transient loading conditions of the cable. The system may include a relief brake that carries from the support structure at least a portion of the weight of the upheld cable. The relief brake has a first end that is operably supported from the support structure, an opposed second end that is operably connected to the cable, and a brake body that is distensible in response to changes in the loading of the cable. Distension of the brake body affects the degree of sag in the cable. In embodiments, the brake body may be a telescoping structure, such as an hydraulic cylinder or a spring, that is operably connected between the support structure and the cable. 
     In another aspect of the present invention, a system for stabilizing a cable upheld by a support structure against transient loading conditions may include a guide frame secured to the support structure and a guide aperture in at least a portion of that guide frame. Slidably retained in the guide aperture is a follower. The follower and the guide aperture cooperate to permit and to affect motion of the cable relative to the support structure in response to changes in the loading of the cable. In one embodiment, the guide aperture may assume the form of an elongated travel slot elevated at an acute angle from the horizontal. 
     In the system, a relief brake may be employed to carry at least a portion of the weight of the cable being upheld from the support structure. An end of the relief brake may be mounted for sliding movement in the guide aperture. The relief brake may be a telescoping structure, and that telescoping structure may distend. 
     In yet another aspect of the present invention, a system for stabilizing a cable upheld by a support structure is provided with relief means operably connected between the support structure and the cable for affecting the sag of the cable in response to loading changes on the cable. The function of the relief means may be performed in one embodiment of the present invention by a telescoping structure, such as an hydraulic cylinder or a spring, that is operably connected between the support structure and the cable. Alternatively, in another embodiment of the present invention, the function of the relief means may be performed by a guide frame secured to the support structure in combination with a guide aperture formed in at least a portion of the guide frame. Slidably retained in the guide aperture is a follower. Together with the guide aperture, the follower permits and affects motion of the cable arising due to changes in the loading of the cable. 
     Although the features and advantages of the present invention are generally described in this summary section and the following detailed description section in the context of embodiments, it shall be understood that the scope of the present invention should not be limited to these particular embodiments. Many additional features, advantages, and fields of use will be apparent to one of ordinary skill in the art in view of the drawings and specification hereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference will be made to embodiments of the invention, examples of which may be illustrated in the accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in the context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments. 
         FIG. 1  is a diagram depicting principles of physics relevant to cables upheld between support structures. 
         FIG. 2  illustrates an example of a support structure for upholding cables. 
         FIGS. 3A and 3B  depict, respectively, an inactive state and an active state of a first embodiment of a system for stabilizing a cable embodying teachings of the present invention. 
         FIG. 4  depicts a second embodiment of a system for stabilizing a cable upheld by an anchor or angle support structure embodying teachings of the present invention. 
         FIG. 5  depicts an active and an inactive state of a third embodiment of a system for stabilizing a cable upheld by a dead-end support structure embodying teachings of the present invention. 
         FIG. 6  depicts an active and an inactive state of a fourth embodiment of a system for stabilizing a cable upheld by a suspension support structure according to teachings of the present invention. 
         FIG. 7  depicts a fifth embodiment of a system for stabilizing a cable upheld by a suspension support structure according to teachings of the present invention. 
         FIG. 8  depicts an active and an inactive state of a sixth embodiment of a system for stabilizing a cable according to teachings of the present invention. 
         FIG. 9  depicts an active and an inactive state of additional embodiments of systems for stabilizing a cable according to teachings of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following description, for purposes of explanation, specific details are set forth in order to provide an understanding of the invention. It will be apparent, however, to one skilled in the art that the invention can be practiced without these details. One skilled in the art will recognize that embodiments of the present invention, described below, may be performed in a variety of ways and using a variety of means. Those skilled in the art will also recognize that additional modifications, applications, and embodiments are within the scope thereof, as are additional fields in which the invention may provide utility. Accordingly, the embodiments described below are illustrative of specific embodiments of the invention and are meant to avoid obscuring the invention. 
     Reference in the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, characteristic, or function described in connection with the embodiment is included in at least one embodiment of the invention. Furthermore, the appearance of the phrase “in one embodiment,” “in an embodiment,” or the like in various places in the specification are not necessarily all referring to the same embodiment. 
       FIG. 1  illustrates principles of physics relevant to a cable  10  upheld between a first support structure  12  and a second support structure  14 . In order to keep under control the upward variation of tension on cable  10 , it is sufficient either to decrease the span L of cable  10  or to allow the sagging of cable  10  to increase from Sag 1  to Sag 2 . This principle is helpfully applicable according to teachings of the present invention to stabilizing cable  10  against failure under situations of increased tension, such as during transient conditions of heavy loading of cable  10 . 
     Embodiments of the present invention involve systems that allow a cable, such as a power line, to increase in sag during transient conditions of heavy loading, and thereafter to regain its routine loading geometry once an intermittent heavy load has been shed from the cable. In one aspect of the present invention, this is accomplished through the use of a telescopic brake and/or through the gravity-driven interaction of mechanical components. Thus, the present invention prevents cable failures, thereby promoting the continuation of uninterrupted cable-delivered user services, such as the delivery of electric power or the transmission of telephone, television, or internet signals. 
       FIG. 2  is a diagram of a typical utility tower  16  used to uphold cables related to the distribution of electric power. Utility tower  16  is shown as an example of a support structure used to uphold cables, and is not to be considered as suggestive that the present invention finds applicability only or even primarily in that field. Utility tower  16  includes a horizontally disposed beam  17  upon which are situated one or more point connectors  18  from which a cable, such as cable  10 , may be supported. 
       FIGS. 3A and 3B  depict, respectively, an inactive state and an active state of a first embodiment of a system embodying teachings of the present invention for stabilizing cable  10  supported from beam point connector  18 . 
       FIG. 3A  depicts the inventive system in an inactive state during normal conditions of loading of cable  10 . Cable  10  connects to an insulating string  20  and is electrically connected to a similar cable on the opposite side of beam point connector  18  by a jumper  22 . Disposed between insulating string  20  and beam point connector  18  is a relief brake  24  that carries the weight of cable  10  to beam point connector  18 . A first end  26  of relief brake  24  is operably connected to beam point connector  18 , and thus to utility tower  16 , while a second end  28  of relief brake  24  is operably connected through insulating string  20  to cable  10 . The body of relief brake  24  between first and second ends  26 ,  28  thereof is distensible in response to increased loading of cable  10 . 
     Thus, as depicted in  FIG. 3B , when intermittent conditions of heavy loading conditions are imposed on cable  10 , the length of relief brake  24  increases, revealing that the embodiment of relief brake  24  shown in  FIGS. 3A and 3B  is a telescoping structure include&#39;s within an outer casing a brake extension  24   a . This distension of relief brake  24  advantageously affords to cable  10  an increase of the sag under such circumstances. Accordingly, relief brake  24  may be a hydraulic cylinder or a spring-loaded telescoping brake connected between beam point connector  18  of utility tower  16  and cable  10  to allow movement of cable  10 . 
       FIG. 4  depicts an inactive state of a second embodiment of a system embodying teachings of the present invention in the system for stabilizing cable  10  upheld by an anchor or angle support structure with a support member represented in  FIG. 4  by beam point connector  18 . In the case illustrated in  FIG. 4 , on each side of beam point connector  18 , a relief brake  24  is interposed between beam point connector  18  and a cable  10 . Brake extension  24   a  is shown in dashed lines housed within the outer casing of relief brake  24 . 
     As can be appreciated from  FIG. 4 , regardless of the specific implementation, one embodiment of the inventive system comprises a telescopic brake between a support structure and the cable that balances increasing cable loading, such as that encountered during ice formation the cable. The telescopic brake may be an hydraulic device or may contain one spring or a plurality of springs, or the like. As the loading on the cable increases, the telescopic brake extends in length. This increases the sag of the cable between the adjacent supporting structures. The telescoping system returns to the inactive state thereof once the condition of heavy loading has been eliminated. It should also be noted that, in embodiments, the present invention may act as or provide the added function of a shock absorber, should a sudden cable loading or unloading occur. One skilled in the art will recognize that the present invention may be utilized in a number of applications, including without limitation, with anchor, angle, and dead-end support structures. 
       FIG. 5  depicts an active state of a third embodiment of a system embodying teachings of the present invention for stabilizing cable  10  when being upheld by a dead-end support structure that includes beam point connector  18 . 
       FIG. 6  depicts an active state and an inactive state of a fourth embodiment of a system for stabilizing cable  10  according to teachings of the present invention. The inactive state is shown in solid lines, and in the active state is shown in dashed lines. 
     In an embodiment, the system may allows relief brake  24 , insulator string  20 , and cable  10  to slide upwardly and horizontally, during transient conditions of heavy loading of cable  10 . This manner of extension in the suspension structure of the system illustrated in  FIG. 6  is accomplished due to a guide aperture  30  formed in a guide frame  32  that is rigidly secured to beam point connector  18 . A follower  34  secured to one end of relief brake  24  is retained for slidable movement in guide aperture  30 . Guide aperture  30  is oriented as to permit this lateral motion in cable  10  relative to utility tower  16  during transient conditions of heavy loading on cable  10 . In the depicted system, translation of cable  10  is conditioned, at least in part, by the geometry of guide aperture  30 , and that geometry may be adjusted to attain various behaviors. 
     In an embodiment, relief brake  24  may distend when the system changes from an inactive to an active state. As illustrated in  FIG. 6 , in an embodiment, the system may be configured to undergo a combination of movement along guide aperture  30  and extension of relief brake  24 . This translation combined with the extensive effect contributed by relief brake  24  has the advantages of being able to displace cable  10  without breaking, and then to return cable  10  to the initial position thereof, once an excess load has been shed therefrom. 
       FIG. 7  depicts a fifth embodiment of a system for stabilizing cable  10  according to teachings of the present invention that resembles the system of  FIG. 6 . An inactive state is shown in solid lines, and in an active state is shown in dashed lines. In an embodiment, guide frame  32  of the system may be a symmetric structure having a horizontal extent X. The distance Y between follower  34  and a connection  35  of insulator string  20  to cable  10  is invariant, because the illustrated system does not, like the system of  FIG. 6 , include a relief brake, such as relief brake  24 . In an embodiment, the movement of the system of  FIG. 7  may be depicted as a pivoting through an angle θ. As indicated in  FIG. 7 , when transition between an inactive and an active state, cable  10  experiences a horizontal displacement indicated as Δa. 
     In the embodiment depicted in  FIG. 7 , it should be noted that as the system moves to an active state on one side of the support structure, the sag of the cable increases but the sag on the opposing side decreases. Such a configuration may be beneficial in many situations, including without limitation, for balancing stress between the cables or when one side of the cable receives a dramatic increase in loading. It should be noted, however, that the embodiment in  FIG. 7  may be adapted for use in any configuration which has only one suspended incoming or one suspended outgoing cable, such as for example a dead-end structure. By using the present invention is such a configuration, the sag of the suspended cable may be affected without adversely affecting the opposing cable because it is not suspended to another support structure. 
       FIG. 8  depicts a sixth embodiment of a system for stabilizing cable  10 , when cable  10  is subjected to variable loading conditions. Inactive and active states of the system are shown, the latter in dashed lines. As depicted, guide frame  32  may include an outer wall or housing to restrict motion of relief brake  24 . As relief brake  24  extends, follower  34  attached thereto slides laterally in guide aperture  30  formed by guide frame  32 . One skilled in the art will recognize that the configuration of guide frame  32  affects the motion of relief brake  24 , but may also provide supplemental support, for example, to counterbalance recoil, once an intermittent heavy loading condition on cable  10  has been alleviated. 
       FIG. 9  depicts embodiments of systems for stabilizing cable  10  according to teachings of the present invention, either with or without a relief brake, such as relief brake  24 . Inactive and active states of the system are shown, the latter in dashed lines. 
     It shall be noted that embodiments of the present invention may or may not be used with a jumper. For example, embodiments depicted in  FIGS. 6-9  do not wire the use of a jumper. It shall also be noted that when two items are referred to as being “carrying from,” “connected to,” “secured to,” “connect between,” “coupled to,” “operably coupled,” “operably connected,” and the like, they are not required to be directly connected. Rather, the items may be connected via one or more intermediary connections. For example, a cable may be connected to a relief brake wherein an insulator is connected between the cable and the relief brake. It shall also be noted that in embodiments, relief brake  24  may be made of non-conducting materials and may, therefore, serve as an electrical insulator to insulate a support structure from a cable. 
     One skilled in the art will recognize that a combination of the embodiments described above may be employed to reduce failures, even under severe loading conditions. An embodiment of the present invention may include the combination of a telescopic brake with a suspension structure extension. One skilled in the art will recognize that such a configuration would be able to stabilize a section of a cable even under very heavy loading conditions. In an embodiment, the combined configuration may be arranged such that one of the telescopic brake and the suspension structure extension initiates before the other. For example, follower  34  on cable  10  may traverse guide aperture  30  before relief brake  24  begins to extend. In an alternative embodiment, both may be employed simultaneously. 
     One skilled in the art will recognize that the embodiments presented herein are presented to illustrate the invention. The present invention may be employed in any of a number of situations where a cable, line, cord, or wire experiences variable loading conditions and may be so modified to fit the application. For example, the present invention may employ frames of different sizes and different dimensions according to the particular application, such as varying power lines and supporting structures, to which they would be adapted in order to be properly restrained under static or dynamic loads. 
     It is possible that a particular section of a cable, especially in the cases of long spans between support structures on uneven ground, may be subject to a heavy load of such a magnitude as to cause such an increase in sag of a cable as will compromise normally maintained minimum ground clearance. If such a condition occurs, it is possible to limit the compromised ground clearance by erecting a pole topped with a cradle directly below the sag apex. If the cable is a power cable, the pole and cradle may be made of insulating material. This arrangement will decrease vertical and torsional loads on the support structures at either end of the cable span involved. 
     An embodiment of the present invention may include additional structures to respond to dynamic shock loading conditions. In an embodiment, the present invention may include one or more damping structures to minimize the effects of dynamic shocks. In an alternative embodiment, one or more of a damper, padding, and a universal joint or joints may be used to help control dynamic forces, such forces resulting from recoil or from strong winds. It should be noted that no specific implementation is critical to the present invention; accordingly, one skilled in the art will recognize that a number of systems may be used to prevent derailment of a track-mounted part or to limit the motion of a moveable part. 
     One skilled in the art will recognize that the present invention possesses a number of benefits. The present invention provides for the permanent, automatic control of loading conditions on cables subject to variable loading conditions. Because embodiments of the present invention automatically allows a cable to return to its original position following the termination of transient loading condition, no costly intervention is needed to reinstate the position of the cable. The configuration of the present invention does not result in eventual damage to cables due to frequent friction between cable and clamps during unusual loading conditions. The present invention not only results in better, more reliable services due to decreased cable failures, but also results in cost savings. 
     Embodiments of the present invention have been disclosed with reference to anchor, angle, dead-end, and suspension structures. One skilled in the art will recognize that the present invention is not limited to those uses, but may in addition be utilized in any situations in which a cable wire, line, cord, or the like is subjected to varying levels of loading. One skilled in the art will recognize that the present invention may be adapted for use with industrial and household equipment and appliances that possess cords or wires. It shall also be noted that the figures are provided by way of illustration only and shall not limit the present invention in any way, including limiting the present invention to those ranges or ratios. Furthermore, the present invention need not be symmetrically disposed. 
     While the invention is susceptible to various modifications and alternative forms, specific examples thereof have been shown in the drawings and are herein described in detail. It should be understood, however, that the present invention is not limited to the particular embodiments disclosed herein. Rather, the present invention is intended to include all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention.