Abstract:
An apparatus for electric wiring, including a housing having a folding stand and a handle, a reel including a flexible tape, a rolling ball-equipped tape leader detachably connected to the lead end of the flexible tape outside the housing, a motor drive controlled to let off/take up the flexible tape, permitting the lead end of the flexible tape to be moved between the inlet of an electric conduit to the outlet thereof to carry an electric wire through the electric conduit, and photo detectors adapted for detecting the movement of the flexible tape so as to automatically cut off power supply from the motor drive when the flexible tape is fully extended out or retracted.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to apparatus for electric wiring, and more particularly to an apparatus for pulling an electric wire through an electric conduit. 
     2. Description of the Prior Art 
     When a building is constructed, electric conduits are provided in each house for electric wiring. When an electric wire is to be installed in an electric conduit, a spring wire is used and inserted from one end of the electric conduit to the other end thereof, and then the electric wire to be installed is fastened to the lead end of the spring wire, and then the spring wire is pulled back to carry the electric wire through the electric conduit. This electric wiring method consumes much labor and working time. 
     SUMMARY OF THE INVENTION 
     This invention relates to apparatus for electric wiring, and more particularly to an apparatus for pulling an electric wire through an electric conduit. 
     According to one aspect of the present invention, the apparatus comprises a housing having a folding stand and a handle, a reel including a flexible tape, a rolling ball-equipped tape leader detachably connected to the lead end of the flexible tape outside the housing, and a motor drive controlled to let off/take up the flexible tape, permitting the lead end of the flexible tape to be moved between the inlet of an electric conduit to the outlet thereof to carry an electric wire through the electric conduit. According to another aspect of the present invention, photo detector means is installed inside the housing to detect the movement of the flexible tape, so as to automatically cut off power supply from the motor drive when the flexible tape is fully extended out or retracted. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows an apparatus for electric wiring according to the present invention; 
     FIG. 2 is an exploded view of the motor drive according to the present invention; 
     FIG. 3 is a sectional view of the apparatus for electric wiring according to the present invention; 
     FIG. 4 is a sectional view of the locating device according to the present invention; 
     FIG. 5 is an applied view of the present invention, showing the flexible tape moved into the electric conduit; 
     FIG. 6 shows a swivel connected between the coupling hole of the flexible tape and the electric wire to be installed according to the present invention; and 
     FIG. 7 is an elevational view of a photo detector module according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings. Specific language will be used to describe same. It will, nevertheless, be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated herein being contemplated as would normally occur to one skilled in the art to which the invention relates. 
     Referring to FIGS. 1,  2 , and  3 , a apparatus for electric wiring in accordance with the present invention comprises a housing  1 . The housing  1  has a folding stand  11  pivotably connected to the bottom of the front open end thereof, a handle  12  fixedly connected to the rear end thereof remote from the folding stand  11 , a forward/backward selector switch  121  at the top side of the handle  12 , a start (on/off) button  122  at the inner side of the handle  12 , a battery chamber  13  at the top side in front of the forward/backward selector switch  121 , and a battery lid  132  covered on the battery chamber  13  to hold down a rechargeable battery  131  in the battery chamber  13 . 
     A reel  201  is mounted inside the housing  1 , and driven by a reversible motor drive to let off/take up a flexible tape  20 . The reversible motor drive is mounted inside the housing  1 , comprising a reversible motor  21 , a pinion  211  fixedly mounted around the output shaft of the reversible motor  21 , a first driven gear  212  and a second driven gear  213  respectively meshed with the pinion  211  at two opposite sides and turned by it in reversed directions, a first driving wheel  214  and a second driving wheel  215  respectively fixedly mounted on the gear shaft of the first driven gear  212  and the gear shaft of the second driven gear  213  at the same side. Two brushes  25 ,  26  are mounted inside the housing  1  at its front open end, and acted against each other. Two parallel guide rollers  23 ,  24  are mounted inside the housing  1  and spaced between the brushes  25 ,  26  and the driving wheels  214 ,  215 . The lead end of the flexible tape  20  is inserted through a locating device  22  inside the housing  1  and retained between the driving wheels  214 ,  215 , and then extended out of the front open end of the housing  1  through the gap between the guide rollers  23 ,  24 , and the gap between the brushes  25 ,  26 . When the forward/backward selector switch  121  is switched to the forward or backward position and the start button  122  is depressed, the reversible motor  21  is driven to turn the driven gears  212 ,  213  in reversed directions, thereby causing the driving wheels  214 ,  215  to let off or take up the flexible tape  20 . Further, an electric cable  204  may be mounted on the reel  201  for connection to an AC power supply outlet to provide electric power supply to the reversible motor  21  through a transformer (not shown). 
     A first photo detector module  27  and a second photo detector module  28  are respectively mounted inside the housing  1 . The first photo detector module  27  is disposed between the driving wheels  214 ,  215  and the reel  201 . The second photo detector module  28  is disposed between the driving wheels  214 ,  215  and the guide rollers  23 ,  24 . Each photo detector module  27  or  28  comprises a light emitting element  271  or  281 , and a photosensitive element  272  or  282  vertically spaced from the light emitting element  271  or  281 . When the photosensitive element  272  or  282  receives the light of the light emitting element  271  or  281 , the photo detector module  27  or  28  immediately cuts off power supply from the reversible motor  21 . The flexible tape  20  has two through holes  202  near the two opposite ends. When one through hole  202  of the flexible tape  20  passes through the gap between the light emitting element  271  or  281  and the photosensitive element  272  or  282 , the photosensitive element  272  or  282  is induced, thereby causing the photo detector module  27  or  28  to cut off power supply from the reversible motor  21 , to prevent idle running of the driving wheels  214 ,  215  (see also FIG.  7 ). 
     The flexible tape  20  has a coupling hole  203  at the lead end. A tape leader  3  is coupled to the lead end of the flexible tape  20  and secured to the coupling hole  203 . The tape leader  3  comprises a box-like mounting frame  31  sleeved onto the lead end of the flexible tape  20 , two parallel projecting strips  311  bilaterally forwardly extended from the front end of the box-like mounting frame  31 , a rolling ball  32  pivotably connected between the parallel projecting strips  311 , a transverse rib  312  raised from the box-like mounting frame  31  at the top, a pressure plate  33  pivoted to the transverse rib  312 , and a spring  34  supported between the mounting frame  31  and the rear end of the pressure plate  33 . The pressure plate  33  has two downward lugs  332  pivoted to the two opposite ends of the transverse rib  312 , and a downward locating pin  331  perpendicularly extended from the bottom side near the front end and forced into the coupling hole  203  of the flexible tape  20 . The spring  34  imparts an upward pressure to the rear end of the pressure plate  33 , causing the pressure plate  33  to force the locating pin  312  into engagement with the coupling hole  203  of the flexible tape  20 . When the rear end of the pressure plate  33  is depressed, the spring  34  is compressed, and the downward locating pin  312  is lifted from the coupling hole  203  of the flexible tape  20 , for permitting the lead end of the flexible tape  20  to be disconnected from the box-like mounting frame  31 . 
     Referring to FIG.  4  and FIG. 2 again, the locating device  22  comprises a first block  221 , a second block  222 , and an adjusting screw  229 . The first block  221  has a transverse channel  223  at the front side, two locating pins  224 ,  225  perpendicularly raised from the front side and vertically spaced by the transverse channel  223 , and a screw hole  228  spaced above and in parallel to the locating pins  224 ,  225 . The second block  222  has a transverse channel  220  at the front side facing the transverse channel  223  of the first block  221 , and two pin holes  226 ,  227  vertically spaced by the transverse channel  220 . When the locating pins  224 ,  225  of the first block  221  are respectively inserted into the pin holes  226 ,  227  of the second block  222 , the first block  221  and the second block  222  are coupled together, and the transverse channels  223 ,  220  are matched together to guide the flexible tape  20 . By turning the adjusting screw  229 , the width of the tape passage which is defined by the transverse channels  223 ,  220  is relatively adjusted. 
     Referring to FIGS. 5 and 6, and FIG. 3 again, when in use, the front open end of the housing  1  is attached to the inlet  402  of the electric conduct  401  and supported in place by the folding stand  11 . When the forward/backward selector switch  121  is switched to the forward position and the start button  122  is depressed, the reversible motor  21  is turned clockwise to turn the driven gears  212 ,  213 , thereby causing the driving wheels  214 ,  215  to let off the flexible tape  20 . When the flexible tape  20  is continuously let off, the tape leader  3  is forced to move through the electric conduit  401  from the inlet  402  to the outlet  403 . When the tape leader  3  is moved out of the outlet  403  of the electric conduit  401 , the tape leader  3  is disconnected from the lead end of the flexible tape  20 , and then a swivel  50  or like means is fastened to the coupling hole  203  of the flexible tape  20  to secure one end of the electric wire  60  to be installed. When the electric wire  60  is connected to the lead end of the flexible tape  20  by the swivel  50 , the forward/backward selector switch  121  is switched to the backward position and the start button  122  is depressed again to turn the reversible motor  21  counter-clockwise, thereby causing the driving wheels  214 ,  215  to take up the flexible tape  20  and the electric wire  60 . Therefore, the electric wire  60  pulled into the electric conduit  401  toward the inlet  402 . 
     The invention is naturally not limited in any sense to the particular features specified in the forgoing or to the details of the particular embodiment which has been chosen in order to illustrate the invention. Consideration can be given to all kinds of variants of the particular embodiment which has been described by way of example and of its constituent elements without thereby departing from the scope of the invention. This invention accordingly includes all the means constituting technical equivalents of the means described as well as their combinations.