Abstract:
A device for installing high-voltage power lines in an overhead status for an initial installation or repair thereof is particularly suited to an overhead power line installation apparatus. The device is capable of achieving easy control for a line winding operation while allowing the line winding operation to cope appropriately with the size of a line winding drum used, and to be conducted without any twisting and tangling of the line being wound.

Description:
RELATED APPLICATIONS 
     This is a Continuation under 35 U.S.C. §120 of the U.S. National Stage Designation of international application no. PCT/KR00/01046, filed Sep. 18, 2000. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to an overhead power line installation apparatus for installing high-voltage power lines in an overhead status for an initial installation or repair thereof, and more particularly to an overhead power line installation apparatus capable of achieving an easy control for a line winding operation while allowing the line winding operation to cope appropriately with the size of a line winding drum used, and to be conducted without any twisting and tangling of the line being wound. 
     BACKGROUND OF THE INVENTION 
     Conventionally, line installation or replacement tasks are conducted using a traditional method. In accordance with the traditional method, a line installation task is conducted by a number of workers who conduct desired tasks on poles or on the ground. That is, an on-ground worker connects one end of a power line to a lower end of a rope hung from a post installed on a line installation area for an initial line installation or line replacement. Thereafter, an on-post worker draws up the rope to lift up the power line, and then attaches the lifted power line to an insulator fixed to a cross arm of the post. After completion of the line installation on one post, the on-ground and on-post workers repeat the above mentioned procedures for the next post. However, such a traditional line installation or replacement method is inconvenient. 
     In order to solve the problem involved in the traditional method, the inventor has proposed an apparatus and method capable of easily installing and replacing overhead power lines. The proposed apparatus and method are disclosed in Korean Patent Application No. 99-18716 filed on May 24, 1999 and titled “Installation Apparatus for Overhead Power Lines and Installation Method Using the Same.” 
     The present invention is intended to improve the proposed overhead power line installation apparatus and method in order to achieve a very effective, economical, rapid, and safe installation conducted in an overhead fashion involving no requirement for power lines to come into contact with the ground while achieving an improvement in installation quality. 
     SUMMARY OF THE INVENTION 
     Therefore, an object of the invention is to provide an overhead power line installation apparatus capable of achieving a very effective, economical, rapid, and safe installation conducted in an overhead fashion involving no requirement for power lines to come into contact with the ground while achieving an improvement in installation quality. 
     Another object of the invention is to provide an overhead power line installation apparatus in which winding of power lines is carried out and controlled using a hydraulic pressure generated from an engine, thereby being capable of improvements in reliability and controllability. 
     Another object of the invention is to provide an overhead power line installation apparatus capable of allowing an installation of a maximum of 4 power lines while completely preventing a twisting phenomenon of those power lines during a winding operation. 
     In accordance with the present invention, these objects are accomplished by providing an overhead power line installation apparatus for installing electric wires respectively wound around wire bobbins in the form of power lines of a 3-phase 3-wire type or power lines of a 3-phase 4-wire type on posts, comprising: a frame; an engine installed on the frame and adapted to generate a drive power; a plurality of wire bobbin driving units arranged on the frame and adapted to rotate the wire bobbins, respectively; a plurality of wire bobbin support units installed on the frame, each of the wire bobbin support units serving to support an associated one of the wire bobbins to allow a rotation and level adjustment of the associated wire bobbin; a wire twist preventing unit arranged on the frame and adapted to prevent the wires from being twisted when the wires are wound around or unwound from the wire bobbins; and a hydraulic circuit receiving the drive power from the engine, thereby generating a hydraulic pressure, the hydraulic circuit serving to control the wire bobbin driving units, the wire bobbin support units, and the wire twist preventing unit using the hydraulic pressure. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above objects, and other features and advantages of the present invention will become more apparent after a reading of the following detailed description when taken in conjunction with the drawings, in which: 
     FIG. 1 is a perspective view of an overhead power line installation apparatus according to an embodiment of the present invention; 
     FIG. 2 is a side view illustrating the overhead power line installation apparatus installed on a vehicle; 
     FIG. 3 is a plan view of the overhead power line installation apparatus, illustrating an arrangement of wire bobbins; 
     FIG. 4 is a plan view of a wire bobbin driving unit included in the overhead power line installation apparatus; 
     FIG. 5 is a partially-enlarged side view of a wire bobbin support unit included in the overhead power line installation apparatus; 
     FIG. 6 is a circuit diagram illustrating a hydraulic circuit included in the overhead power line installation apparatus; and 
     FIG. 7 is view illustrating the using condition of the overhead power line installation apparatus. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIG. 1, the reference numeral  100  denotes a frame included in an overhead power line installation apparatus according to an embodiment of the present invention. The frame  100  supports a plurality of wire bobbins. The frame  100  has a size capable of allowing the frame  100  to be carried on a vehicle on which a crane is installed. 
     The overhead power line apparatus is adapted to use a maximum of 4 wire bobbins, so as to install power lines of the 3-phase 3-wire type or power lines of the 3-phase 4-wire type. 
     An engine assembly  200  is installed on the frame  100  at one side of the frame  100 . 
     The engine assembly  200  includes an engine  202 , a reduction gearing  204  for reducing the output from the engine  202 , and a pair of hydraulic pumps  1002  and  2002  for generating a hydraulic pressure in accordance with an output from the engine  202  transmitted thereto via the reducing gearing  204 , and transmitting the hydraulic pressure to a hydraulic circuit communicating therewith. 
     The frame  100  also carries four wire bobbin driving units  300  for driving a maximum of four wire bobbins B 1 , B 2 , B 3 , and B 4 . 
     The configuration of one wire bobbin driving unit  300  is illustrated in FIG.  4 . Referring to FIG. 4, each wire bobbin driving unit  300  includes a pair of roller support shafts  301  and  302  rotatably mounted to the frame  100  while being spaced apart from each other in a longitudinal direction of the frame  100 . Each of the roller support shafts  301  and  302  has a hexagonal cross-sectional shape. A pair of drive rollers  311  and  312  are fitted around the roller support shaft  301  at both ends of the roller support shaft  301 , respectively. The drive rollers  311  and  312  are slidable along the roller support shaft  301  in order to adjust the space defined therebetween in accordance with the size of a wire bobbin to be rotatably supported by the drive rollers  311  and  312 . In similar, a pair of drive rollers  313  and  314  are fitted around the roller support shaft  302  at both ends of the roller support shaft  302 , respectively. The drive rollers  313  and  314  are slidable along the roller support shaft  302  in order to adjust the space defined therebetween in accordance with the size of a wire bobbin to be rotatably supported by the drive rollers  313  and  314 . The roller support shafts  301  and  302  are connected to each other by a chain  321 . The roller support shaft  301  is connected to a roller driving hydraulic motor  330  (FIG. 6) via a power transmission, so that it rotates normally or reversely in accordance with a rotation force transmitted from the roller driving hydraulic motor  330 . 
     The overhead power line installation apparatus of the present invention also includes a wire bobbin support unit  400  associated with each wire bobbin driving unit  300 . The configuration of the wire bobbin support unit  400  is best shown in FIG.  5 . The wire bobbin support unit  400  is adapted to maintain a wire bobbin, for example, the wire bobbin B 1 , in a state rotatably supported by the drive rollers  311 ,  312 ,  313 , and  314  of the associated wire bobbin driving unit  300  while adjusting the level of the wire bobbin B 1  in accordance with the size or diameter of the wire bobbin. 
     As shown in FIG. 5, the wire bobbin support unit  400  includes a pair of guide posts  402  each fixed at the lower end thereof to the frame  100  while extending upwardly from the frame  100 . The guide posts  402  are arranged between the roller support shafts  301  and  302  outside the opposite ends of the wire bobbin driving unit  300  while being spaced apart from each other in a lateral direction of the frame  100 . Each guide post  402  is provided with a vertically-extending guide passage. A lower support member  412  and an upper support member  414  are also provided to rotatably support each end of a central shaft S of the wire bobbin B 1  in a clamped state. The support members  412  and  414  are hingably coupled to each other by a hinge pin  417  so that they hinge between a clamping state, in which they clamp the central shaft S therebetween, and a releasing state in which they release the central shaft S. In order to maintain the support members  412  and  414  in the clamping state, a pin  416  is also provided, which is adapted to be inserted into pin holes extending through the support members  412  and  414 . The lower support member  412  is received in the guide passage of the guide post  402  so that it slides vertically along the guide passage. A lift cylinder  420  is fixedly mounted to the frame  100  while extending upwardly along the guide passage of the guide post  402 . The lower support member  412  is fixedly mounted, at the lower end thereof, to the upper end of a piston rod included in the lift cylinder  420 . As the piston rod of the lift cylinder  420  moves vertically, the support members  412  and  414  slide vertically along the guide passage of the guide post  402 . 
     The lift cylinder  420  is coupled to a hydraulic circuit shown in FIG.  6  and described hereinafter, so that it is driven by the hydraulic circuit in a controlled fashion. 
     A wire twist preventing unit  500  is arranged at a portion of the frame  100  opposite to the engine assembly  200  in order to prevent wires from being twisted when they are wound around or unwound from a wire bobbin rotatably supported by each wire bobbin support unit  400 . 
     The configuration of the wire twist preventing unit  500  is best shown in FIG.  1 . Referring to FIG. 1, the wire twist preventing unit  500  includes a plurality of vertically-extending feeding screw support bars  510  fixedly mounted, at the lower ends thereof, to the end of the frame  100  opposite to the engine assembly  200  while being spaced apart from one another in the lateral direction of the frame  100 . The wire twist preventing unit  500  also includes a plurality of feeding screws  521 ,  522 ,  523 , and  524  each axially mounted between adjacent ones of the feeding screw support bars  510 , and a plurality of feeding guide shafts  531 ,  532 ,  533 , and  534  respectively associated with the feeding screws  521 ,  522 ,  523 , and  524 . Each of the feeding guide shafts  531 ,  532 ,  533 , and  534  is axially mounted between the feeding screw support bars  510 , to which an associated one of the feeding screws  521 ,  522 ,  523 , and  524  is mounted, while being parallel to the associated feeding screw. The wire twist preventing unit  500  further includes a plurality of slide blocks  541 ,  542 ,  543 , and  544  each coupled, at a lower end thereof, to an associated one of the feeding screws  521 ,  522 ,  523 , and  524  to slide along the associated feeding screw in accordance with a rotation of the associated feeding screw. Each of the slide blocks  541 ,  542 ,  543 , and  544  is slidably fitted, at an upper end thereof, around an associated one of the feeding guide shafts  531 ,  532 ,  533 , and  534 , so that its slide movement is guided by the associated feeding guide shaft. A wire, which is to be wound around or unwound from a wire bobbin, extends through an opening defined in each of the slide blocks  541 ,  542 ,  543 , and  544 . By this configuration, when a wire is wound around or unwound from a wire bobbin, an associated one of the slide blocks  541 ,  542 ,  543 , and  544  guides a movement of the wire while sliding along the associated feeding screw in a state guided by the associated feeding guide shaft in accordance with a rotation of the associated feeding screw, thereby causing the wire to be uniformly wound around or unwound from the wire bobbin without any twist thereof. In order to drive the feeding screws  521 ,  522 ,  523 , and  524 , feeding screw driving hydraulic motors  551 ,  552 ,  553 , and  554  are coupled to those feeding screws  521 ,  522 ,  523 , and  524 , respectively. These hydraulic motors  551 ,  552 ,  553 , and  554  are driven in a controlled fashion by the hydraulic circuit of FIG.  6 . 
     A pair of limit switches LS 1  and LS 2  are arranged at opposite ends of each feeding guide shafts  531 ,  532 ,  533 , or  534 , respectively, in order to respectively detect positions where an associated one of the slide blocks  541 ,  542 ,  543 , and  544  changes its sliding direction. In the illustrated case, each limit switch LS 1  or LS 2  is attached to a desired one of the feeding screw support bars  510 . 
     The above mentioned hydraulic circuit included in the overhead power line installation apparatus according to the present invention is adapted to control the rotation and lifting of one wire bobbin and the twist prevention operation for the wire bobbin. In other words, the overhead power line installation apparatus includes a plurality of hydraulic circuits respectively associated with the wire bobbin driving units  300 . The configuration of one hydraulic circuit is illustrated in FIG.  6 . 
     As shown in FIG. 6, the hydraulic circuit includes a first hydraulic circuit  1000  for controlling the roller driving hydraulic motor  330  and the lift cylinders  420 . The first hydraulic circuit  1000  includes a large-capacity hydraulic pump which is the hydraulic pump  1002  mentioned above. The first hydraulic circuit  1000  also includes a hydraulic motor direction control valve  1004  adapted to control the roller driving hydraulic motor  330 , and a cylinder direction control valve  1006  adapted to control the lift cylinders  420 . The hydraulic motor direction control valve  1004  and the cylinder direction control valve  1006  communicate with a central passage of the hydraulic pump  1002 . The first hydraulic circuit  1000  further includes joystick valves  1008  and  1010  for controlling the hydraulic motor direction control valve  1004  and the cylinder direction control valve  1006  using pilot pressures, respectively. 
     The hydraulic circuit includes a second hydraulic circuit  2000  for controlling an associated one of the feeding screw driving hydraulic motors, for example, the hydraulic motor  551 . The second hydraulic circuit  2000  includes a low-capacity hydraulic pump which is the hydraulic pump  2002  mentioned above. The second hydraulic circuit  2000  also includes a direction change valve  2004  communicating with a central fluid passage of the hydraulic pump  2002 . The direction change valve  2004  changes the rotation direction of the hydraulic motor  551  in accordance with electrical signals outputted from the limit switches LS 1  and LS 2 , thereby changing the rotation direction of the associated feeding screw  521 . 
     Now, the operation of the overhead power line installation apparatus having the above mentioned configuration according to the present invention will be described with reference to the illustrated hydraulic system. 
     In order to conduct a line installation or replacement task using the overhead power line installation apparatus of the present invention, the frame  100  of the apparatus is first carried on a vehicle  20  carrying a crane  10 , as shown in FIG.  7 . Thereafter, the wire bobbins B 1 , B 2 , B 3  and B 4  wound with wires are put on the drive rollers of the associated wire bobbin driving units  300 , respectively, using the crane  10 . 
     The procedure for putting the wire bobbin B 1  on the drive rollers of the wire bobbin driving unit  300  will now be described. 
     At each guide post  402  of the wire bobbin support unit  400  associated with the wire bobbin driving unit  300 , the upper support member  414  is hingably moved about the hinge pin  417  with respect to the lower support member  412  so that the support members  412  and  414  are opened to allow an associated end of the central shaft S of the wire bobbin B 1  to be put on the lower support member  412 . At this time, the lower support member  412  is maintained at a lifted position thereof by the lift cylinder  420 . The wire bobbin B 1  is then put on the wire bobbin support unit  400  in such a fashion that both ends of the central shaft S of the wire bobbin B 1  are placed on the lower support members  412  received in the guide posts  402  in a lifted state. Thereafter, the central shaft S is clamped at each end thereof by the lower and upper support members  412  and  414 . That is, at each end of the central shaft S, the upper support member  414  is hingably moved to its original position, that is, a clamping position, in such a fashion that the pin holes of the lower and upper support members  412  and  414  are aligned with each other. In this state, the pin  416  is inserted into the aligned pin holes of the support members  412  and  414 . Thus, the support members  412  and  414  maintains the central shaft S in a clamped state, as shown in FIG.  5 . 
     In this state, the joystick valve  1010  is manipulated to downwardly move the piston rod of the lift cylinder  420  arranged at each guide post  402 , thereby causing the wire bobbin B 1  to come into contact with the drive rollers  311 ,  312 ,  313 , and  314  at the outer peripheral surfaces of wheels included in the wire bobbin B 1 , as shown in FIG.  5 . 
     In this state, the wire bobbin B 1  is in linear contact with the drive rollers  311 ,  312 ,  313 , and  314 . Accordingly, when the roller support shafts  301  and  302  serving to rotate the drive rollers  311 ,  312 ,  313 , and  314 , are rotated in accordance with a rotation of the roller driving hydraulic motor  330 , the wire bobbin B 1  rotates in a direction corresponding to the rotation direction of the roller driving hydraulic motor  330 . 
     The unwinding of the wire wound around each wire bobbin B 1 , B 2 , B 3 , or B 4  can be conducted in accordance with the rotation of the associated roller driving hydraulic motor  330  or the movement of the vehicle  20 . Where the rotation of the roller driving hydraulic motor  330  is used, the wire bobbin is in contact with the drive rollers  311 ,  312 ,  313 , and  314  at the outer peripheral surfaces of its wheels. On the other hand, where the movement of the vehicle  20  is used, the outer peripheral wheel surfaces of the wire bobbin are spaced apart from the drive rollers  311 ,  312 ,  313 , and  314 . In this connection, the level of the wire bobbin is adjusted in accordance with a manipulation for the lift cylinders  420 . 
     In accordance with a line installation or replacement task given, three or four wire bobbins are used. Since each wire bobbin used has a wheel width determined depending on the task, the space between the drive rollers,  311  and  312 , or,  313  and  314 , mounted to each roller support shaft  301  or  302  is correspondingly adjusted by axially sliding those drive rollers along the roller support shaft. 
     Under the condition in which the central shaft S of each wire bobbin B 1 , B 2 , B 3 , or B 4  are supported by the associated lift cylinders  420 , and the wire bobbin is in close contact with the drive rollers  311 ,  312 ,  313 , and  314  at its wheels, the leading end of the wire wound around the wire bobbin is slightly unwound by slightly rotating the wire bobbin. 
     The operator then extends the unwound leading end of the wire through rollers R 1  and R 2  freely rotatably mounted to the upper end of a telescopic boom  11  included in the crane  10 , thereby holding the leading end of the wire on the upper end of the boom  11 . In this state, the operator drives the vehicle  20  in order to place the vehicle  20  at a post area where a post  1  to be initially subjected to the task is located. 
     Once the vehicle  20  is placed at the post area, the level of the vehicle  20  is adjusted to be horizontal, using jacks which have a conventional configuration and serve to firmly support the vehicle  20  on the ground. Although not shown, a level is attached to the rear surface of a boot provided at the vehicle  20  in order to accurately adjust the level of the vehicle  20 . 
     In a state in which the vehicle  20  is horizontally maintained, the boom  11  is extended so that its upper end reaches a level at which the on-post worker is positioned. Simultaneously with the extension of the boom  11 , each bobbin B 1 , B 2 , B 3 , or B 4  is rotated to unwound the wire, so that it does not interfere with the extension of the boom  11 . 
     For the rotation of each bobbin B 1 , B 2 , B 3 , or B 4 , the operator manipulates the lever of the joystick valve  1008  to drive the associated roller driving hydraulic motor  330 . When the hydraulic motor  330  is driven, the associated drive rollers  311 ,  312 ,  313 , and  314  are rotated, so that the wire bobbin, which is in contact with the drive rollers at the outer peripheral edge thereof, is rotated. 
     When the boom  11  is extended so that its upper end reaches the level at which the on-post worker is positioned, the operator stops the extension of the boom  11  while temporarily stopping the rotation of the wire bobbin. 
     Under this condition, the on-post worker can conduct a line installation or replacement task by taking the wires, held on the upper end of the boom  11 , from the boom  11  one by one. Accordingly, the line installation or replacement task can be carried out with a superior security and a superior workability, as compared to the conventional method in which the on-post work receives wires one by one from the on-ground worker, and then lifts up the wires onto the post. 
     After completion of the task for one post, the operator moves the vehicle  20  to the next post. The movement of the vehicle  20  is carried out in a state in which the wires are held on the upper end of the boom  11 . To this end, the wires should be continuously unwound during the movement of the vehicle  20 . Accordingly, the operator manipulates the lever of the joystick valve  1010  to drive the roller driving hydraulic motor  330  while controlling the number of rotations of the roller driving hydraulic motor  330  in accordance with the moving speed of the vehicle  20 , under the condition in which each wire bobbin B 1 , B 2 , B 3  or B 4  is in contact with the associated drive rollers  311 ,  312 ,  313 , and  314 . 
     When the vehicle  20  stops, the operator manipulates the lever of the joystick valve  1010  to position the lever at its neutral position, thereby stopping the hydraulic motor  330 . As a result, the wire is unwound from the wire bobbin no longer. 
     During the movement of the vehicle  20 , the wires are moved in an overhead fashion without coming into contact with the ground. When the upper end of the boom  11  reaches the worker on the next post as the vehicle  20  moves to the next post, the movement of the vehicle  20  and the rotations of the wire bobbins are stopped. The on-post worker then conducts a line installation or replacement task by taking the wires, held on the upper end of the boom  11 , from the boom  11  one by one in the same fashion as mentioned above. After completion of the above mentioned line installation or replacement task, line installation or replacement tasks for other posts in the task area are then sequentially carried out in the same fashion as mentioned above. 
     Meanwhile, after completion of all line installation or replacement tasks, the wires held in a loosened state among the posts should be tightened so that they are taut. 
     To this end, the wires are separated from the boom  11 , and then inserted through the slide blocks  541 ,  542 ,  543 , and  544 . In this state, the hydraulic motors  330  are rotated in order to wind the wires around the wire bobbins B 1 , B 2 , B 3 , and B 4 , respectively. 
     That is, the operator manipulates the lever of the joystick valve  1010 , thereby changing the actuating direction of the direction control valve  1004  to reversely rotate the roller driving hydraulic motors  330 . As a result, the drive rollers  311 ,  312 ,  313 , and  314  operatively connected to each roller driving hydraulic motor  330  are reversely rotated, thereby reversely rotating the associated wire bobbin. 
     Thus, the wires are wound around the wire bobbins B 1 , B 2 , B 3 , and B 4 . 
     During the winding of the wires, the feeding screw driving hydraulic motors  551 ,  552 ,  553 , and  554  rotate repeatedly in normal and reverse directions in accordance with ON/OFF switching operations of the limit switches LS 1  and LS 2 . Accordingly, the slide blocks  541 ,  542 ,  543 , and  544 , which are coupled to the feeding screws  521 ,  522 ,  523 , and  524 , respectively, reciprocate laterally. 
     As a result, the wires are uniformly wound around the associated wire bobbins B 1 , B 2 , B 3 , and B 4  while being gradually shifted in a width direction of the wire bobbins. Thus, the present invention makes it possible to achieve an effective winding of wires without any requirement of a number of workers or an increased consumption of labor, as compared to conventional cases. 
     Since the hydraulic motors  330  adapted to supply a drive force required in the winding of wires are of the reversible type, they can also be effectively used in the unwinding of wires or in other cases in which a reverse drive force is required. 
     When the wires are completely installed in an overhead fashion and in a tight state among posts after completion of the winding operation, the worker on each post connects the wires to the clamp of a suspension insulator fixed to a cross arm of the post. Finally, the on-post worker cuts the wires extending from the wire bobbins. Thus, the line installation or replacement task is completed. 
     As is apparent from the above description, the present invention provides an overhead power line installation apparatus capable of conducting a line installation in an overhead fashion involving no requirement for power lines to come into contact with the ground during the carriage of those power lines. Accordingly, it is possible to protect the claddings of the power lines. Also, an enhanced reliability is provided because winding and unwinding operations for power lines are hydraulically controlled. 
     Accordingly, it is possible to reduce the consumption of labor while providing an enhanced security for workers. In particular, these effects are more remarkably provided in the case of a multi-line installation. 
     Thus, the present invention enables a rapid line installation with a reduced number of workers, thereby reducing the line installation costs. In addition, it is possible to minimize the traffic inconvenience resulting from the line installation. 
     Although the preferred embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.