Abstract:
Switch apparatus is disclosed. The switch apparatus has an enclosure, having a openable cover, a switch disposed within the enclosure, a handle in operative communication with the switch, a spring in biasing communication with the handle, and interlocking members. The interlocking members, the handle, the biasing spring and the switch having positions relative to each other such that the interlocking members lock the cover in a closed position in response to the handle being biased toward an OFF position, and the switch contacts being closed. Further disclosed is a method for unlocking a closed cover of a switch apparatus. A spring biased handle is changed to an OFF biased position from an ON biased position passing through a non-biased position. Subsequent thereto, a switch being changed from a closed circuit to an open circuit position. Subsequent thereto, interlocking members are changed from an interlocked to a non-interlocked position.

Description:
BACKGROUND OF THE INVENTION 
   This invention relates to an interlocking device for preventing the opening of a cover for an enclosure for a switch or circuit breaker, and more specifically it pertains to an interlock for preventing the cover from being opened while the switch is in the ON or closed circuit position. 
   Switch apparatus of various types such as circuit breakers have been contained within enclosures in a manner well known in the art. The enclosures are normally provided with handles that are operatively connected to the enclosed switch for actuating the switch to the OFF or open circuit position when the cover is to be opened. It is common for these handles to include a latch interlock feature that prevents the cover of the enclosure from being opened when the handle is rotated to its fully ON position. In some instances, however, it may be desirable to lock the cover when the handle is not in its full ON position. Accordingly, there is a need for improvements in the art of switch enclosure interlocks. 
   BRIEF DESCRIPTION OF THE INVENTION 
   An embodiment of the invention includes an enclosure that has a base and a cover, the cover openably covering the base, at least one switch disposed within the enclosure, a handle in operative communication with the switch, a spring in biasing communication with the handle, and interlocking members, one of which being in operable communication with the handle, the other being fixedly attached to the cover. The interlocking members, the handle, the biasing spring and the switch having positions relative to each other such that the interlocking members lock the cover in a closed position in response to the handle being biased toward an OFF position, and the switch contacts being closed. 
   Another embodiment of the invention includes a method for unlocking a closed cover of a switch apparatus. A spring biased handle is changed to an OFF biased position from an ON biased position passing through a non-biased position. Subsequent thereto, a switch being changed from a closed circuit to an open circuit position. Subsequent thereto, interlocking members are changed from an interlocked to a non-interlocked position. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
       FIG. 1  is a perspective view of an exemplary embodiment of the switch apparatus of the present invention; 
       FIG. 2  is a partial side view of the inside of the enclosure of  FIG. 1 ; 
       FIG. 3  is a partial side view taken along arrows  3 - 3  of  FIG. 2 ; 
       FIG. 4  is a partial end view of the spring guide of  FIG. 2  taken along arrow  4 ; 
       FIG. 5  is a side view of an embodiment of a switch assembly for use in accordance with an embodiment of the invention; 
       FIG. 6  is a front view of the switch assembly of  FIG. 5 ; 
       FIG. 7  shows five zones created from six possible handle positions for use in accordance with an embodiment of the invention; 
       FIG. 8  is a partial side view similar to that of  FIG. 2  of another embodiment of the invention; 
       FIG. 9  is an external side view of another embodiment of the invention; 
       FIG. 10  is a cross sectional view of  FIG. 9  taken along arrows  10 - 10 ; 
       FIG. 11  is another cross sectional view of  FIG. 9  taken along arrows  10 - 10  showing an alternate positional configuration from that of  FIG. 10 ; 
       FIG. 12  is another cross sectional view of  FIG. 9  taken along arrows  10 - 10  showing another exemplary embodiment; and 
       FIG. 13  is a perspective view of an exemplary embodiment of the switch apparatus of the present invention with an alternate cover. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Embodiments will now be described, by way of example only, with reference to the accompanying drawings which are meant to be exemplary, not limiting, and wherein like elements are numbered alike in the Figures. 
   The perspective view in  FIG. 1  is an embodiment of a switch apparatus  1  showing a partially cut away cover  3  over a base  13 . The cover  3  and base  13  create an enclosure  11  that encloses a volume  15 . A handle  2  is disposed external to the enclosure  11  is mounted to a shaft  4  that protrudes through a hole  7  in wall  6  and through a hole  9  in bracket  8 . The handle  2  is fixedly attached to the shaft  4  such that rotational movement of the handle  2  causes the shaft  4  to rotate. A drive rotor  12 , disposed internal to enclosure  11 , is also fixedly attached to the shaft  4 . At least one switch blade  14  is fixedly attached to the shaft  4  and is driven rotationally by the shaft  4  which is driven by the handle  2 . Stated another way, the handle  2  is in operative communication with the switch blade  14 . Therefore the handle  2 , drive rotor  12 , shaft  4  and switch blade  14  all pivot about an axis  5 . 
   Rotation of the handle  2  in the direction of arrow ON rotates the shaft  4 , which turns the drive rotor  12 , and the switch blade  14 , which closes a circuit. When the handle  2  is rotated in the direction of arrow OFF, the shaft  4  rotates the drive rotor  12  and the switch blade  14 , which opens the circuit. Through the above configuration the handle  2  of the switch apparatus  1  is used to turn ON (close the switch) and turn OFF (open the switch) a circuit in which the switch apparatus  1  is electrically connected. The cover  3  is mounted to the base  13  by at least one hinge  16  located on wall  18  of the base  13 . Since wall  18  is opposite wall  6  the cover  3  swings open from the side of the switch apparatus  1  where the handle  2  is located as shown by the arrow labeled open. 
   Referring to  FIGS. 2 and 3 , a latching member  26  is integrally formed on a drive rotor  12  that is fixedly attached to the shaft  4  and thus pivots about axis  5 . The latching member  26  travels in an arc shaped path concentric with the axis  5  as the handle  2  is rotated, as such, the latching member  26  is in operable communication with the handle  2 . An arcuate surface  24  is formed on a receiver member  22  that is fixedly attached to the inside of the cover  3  near the handle  2 . The partial cover  3  in  FIG. 2  is shown in a closed position, which is defined as the cover position that locates the receiver member  22  relative to the base  13  such that the latching member  26  can interlock with the arcuate surface  24 . The interlocking of the latching member  26  with the arcuate surface  24  establishing a locked condition for the cover  3 . 
   The arcuate surface  24  is opened on the end toward the OFF position of the handle  2 , such that the latching member  26  can travel beyond the arc length and out the open end of the arcuate surface  24  resulting in a non-interlocked condition of the latching member  26  to the arcuate surface  24 . The latching member  26  being in a position beyond the arcuate surface  24  defining an unlocked position. 
   A biasing spring  28  is incorporated to force the handle  2  toward either the ON or the OFF direction. The biasing spring  28  rides along a spring guide  30  and is compressed between a guide sleeve  32  and a fork  34  that is fixedly attached to the spring guide  30 . A headed pin  36  is slidably engaged in through holes of both tines of the fork  34  and a rotor flange  38 . The tines of the fork  34  are straddling the rotor flange  38  thereby pivotally fixing the fork  34  to the rotor flange  38  at headed pin  36 . An E-clip  33  attached to the end of the headed pin  36  prevents the headed pin  36  from backing out of the through holes (holes not shown but located in area around headed pin  36 ) of the fork  34  and the rotor flange  38 . Referring to  FIG. 4 , the guide sleeve  32 , fixedly attached to the pivot bracket  8 , has a slotted hole  31  that is large enough for the spring guide  32  to slide through the slotted hole  31  while creating a stop  35  for the end of the biasing spring  28  that is in contact with the guide sleeve  32 . 
   The guide sleeve  32  and hole in the rotor flange  38  for the headed pin  36  are positioned relative to each other and to the handle  2  such that the length of the biasing spring  28  is longer in response to the handle  2  being at the handle&#39;s extremes positions of travel as compared to being at the handle&#39;s middle position of travel. Thus, the biasing spring  28  creates a rotational force to move the handle  2  toward either the ON or the OFF direction, therefore, the spring  28  is in biasing communication with the handle  2 . The handle position creating the shortest biasing spring  28  is called TDC for top-dead-center. At TDC there is no rotational force from the biasing spring  28  acting on the handle  2 . Very close in either direction from TDC the frictional forces are greater than the rotational force from the biasing spring  28  and the handle  2  if released will not move. This area is called the friction circle. The handle  2  must be moved beyond the frictional circle in order for it to move freely based on the force of the biasing spring  28  only. The handle position of the TDC point can be set anywhere within the full range of the movement of the handle  2  by the locations of the guide sleeve  30  and the hole in the rotor flange  38  relative to the handle  2  and the axis  5 . 
   Referring to  FIGS. 5 and 6 , a switch blade  14  is fixedly attached to shaft  4  and both rotate about axis  5 . The rotation of the switch blade  14  toward the ON from the OFF direction first brings switch blade  14  into contact with a line contact  72  and then with a load contact  74 . The switch blade  14  being in contact with both the line contact  72  and the load contact  74  defines a closed circuit or ON condition. An open circuit, or OFF condition exists if the switch blade  14  is not in contact with both the line contact  72  and the load contact  74  simultaneously. 
   Referring to  FIG. 7 , five zones are defined by the relationships of; the cover being locked or not, the switch being ON or OFF and the handle  2  being biased in the ON, OFF or no direction. The five zones; A, B, C, D and E exist between the limits of the movement of the handle  2 , with A being the furthest in the ON direction, and E being the furthest in the OFF direction. Zone A being defined by the following conditions; the cover  2  is locked, the switch is ON and the handle  2  is biased in the ON direction. Zone B being defined by the following conditions; the cover  2  is locked, the switch is ON and the handle  2  is in the friction circle (not biased). Zone C being defined by the following conditions; the cover  2  is locked, the switch is ON and the handle  2  is biased in the OFF direction. Zone D being defined by the following conditions; the cover  2  is locked, the switch is OFF and the handle  2  is biased in the OFF direction. Zone E being defined by the following conditions; the cover  2  is unlocked, the switch is OFF and the handle  2  is biased in the OFF direction. Zone C is of particular interest since it shows that the handle can be biased toward OFF while the cover is locked and the switch is in the ON position. 
   Referring now to  FIG. 8 , an alternate embodiment of the invention is shown. In this embodiment a latching member  48  is formed on a latching plate  46  that is fixedly attached to the drive rotor  12 . And, a receiver finger  44  is formed on a receiver member  42  that is fixedly attached to the cover  3 . The latching member  48  of the latching plate  46  rotates with the drive rotor  12  and the handle  2  to interlock with a receiver finger  44  of the receiver member  42 . The latching member  48  is axially aligned with the receiver finger  44  such that the interlocking of the latching member  48  with the receiver finger  44  lock cover  3  in a closed position. The lengths of the latching member  48  and the receiver finger  44  can be set to interlock with each other at any position of the handle  2  to lock the cover  3  closed. 
   The interlocking members of the embodiments shown in  FIGS. 1 and 8 , are disposed within the enclosure  11 , preventing defeat of the interlocks while the cover  3  is closed. In an alternate embodiment, and referring now to  FIG. 9 , interlocking members are disposed outside the enclosure of switch apparatus  10  and can therefore be defeated (as will be described below) while the cover  103  is closed. 
   A latching member  56  is movably attached to a handle  102  and travels in a radial arc  58  concentric with an axis  105  of shaft  104  when the handle  102  is rotated. A receiver member  52  is fixedly attached to the cover  103  and has an arcuate surface  54  that is concentric with the shaft  104  in response to the cover  103  being closed. The radial arc  58  is larger than the radius of the arcuate surface  54  to create a small clearance gap between the latching member  56  and the arcuate surface  54 . Referring to  FIGS. 10 and 11 , the latching member  56  protrudes from the handle  102  in a direction towards the cover  103  to interlock with the arcuate surface  54  of the receiver member  52 . Thus the latching member  56  and the receiver member  52  act as an interlock to lock the cover  103  in the closed position. 
   Referring back to  FIG. 9 , the latching member  56  can travel in an arc length that is longer than the arc length of the arcuate surface  54 . This additional travel is in the direction of arrow OFF, such that the latching member  56  can travel beyond the arc length of the arcuate surface  54  in response to the handle  102  being rotated sufficiently far in the direction of the arrow OFF, as such, a non-interlocked condition of the latching member  56  with the receiver member  52  results, thereby allowing the cover  103  to be opened. 
   Referring back to  FIGS. 10 and 11 , the latching member  56  is movably attached to the handle  102 .  FIG. 11  shows the latching member  56  in interlocked position with arcuate member  54 , and  FIG. 10  shows the latching member  56  not interlocked with arcuate member  54 , thus creating a defeatable interlocking cover  103 . This embodiment incorporates a handle  102  with a spring loaded pin  100  as the latching member  56 . 
   A shaft  108  of the latching member  56  is slidably engaged in a hole  110  through the handle  102 . A spring  112  positioned around the shaft  108  is in compression between the handle  102  and a head  114  of the latching member  56  forcing the head  114  of the latching member  56  in a direction away from the handle  102 . A pin  116  fixedly attached to the shaft  108  protrudes a radial distance greater than the radius of the hole  110  preventing the shaft  108  from withdrawing from the hole  110  in the handle  102 . Two slots  117 / 118  cut into a surface  120  of the handle  102  are positioned 180 degrees from each other around the perimeter of the hole  110 . The slots create cavities in the surface  120  of the handle  102  that the pin  116  is forced into by the spring  112 , thereby, preventing the latching member  56  from rotating relative to the handle  102 . To move the pin  116 , for example, from slot  117  to slot  118 , the spring  112  must be compressed while the latching member  56  is rotated through 180 degrees. 
   The slots  117 / 118  are cut to different depths from the surface  120  to create two levels of protrusion of the latching member  56  from the surface  120 . The depth of slot  117  is shallow to hold the latching member extended over the arcuate surface  54  to lock the cover  103  closed, whereas the depth of slot  118  is deep to position the latching member  56  with no protrusion from surface  120  thereby preventing locking of the cover  103 . This embodiment, therefore, permits the interlocking of the cover  103  to be defeated. 
     FIG. 12  shows another embodiment of a defeatable interlocking cover. As in the previous embodiment, a latching member  156  is movably attached to the handle  202 . The latching member  156  is a screw and has a threaded shaft  208  that screws into a threaded hole  210  through the handle  202 . By screwing the latching member  156  in until a screw head surface  214  is in contact with a handle surface  221 , the shaft  208  will protrude from a handle surface  220  sufficiently to interlock with the arcuate member  54  to lock the cover  103  closed. By screwing the latching member  156  out until an upset  224  on the last thread of shaft  208  binds with hole  210 , the shaft will not protrude from the surface  220  of the handle  102 , and will therefore not interlock with the arcuate member  54 . This embodiment, therefore, permits the interlocking of the cover  103  to be defeated. 
   The perspective view in  FIG. 13  is an embodiment of a switch apparatus  301  showing a cover  303  opened over a base  313 . The cover  303  and the base  313  create an enclosure  311  that encloses a volume  315 . The cover  303  is mounted to the base  313  by hinges  316  located on walls  318  and  306  of the base  313 . A drive rotor  312  being in operative communication with the handle  302  rotates as handle  302  rotates. The latching member  326 , being formed of drive rotor  312 , rotates in response to the handle  302  being rotated. The latching member  326  engages with arcuate surface  324  of receiving member  322  attached to the cover  303  to lock the cover  303  closed in response to the handle  302  being rotated toward arrow ON while the cover  302  is closed over the base  313 . It should be understood that other embodiments may have the cover  303  pivot about hinges located on wall  319  without deviating from the scope of the present invention. 
   While the description above refers to particular embodiments of the present invention, it will be understood that many modifications may be made without departing from the spirit thereof. The accompanying claims are intended to cover such modifications as would fall within the true scope and spirit of the present invention.