Abstract:
A fuse block having a rotary operator communicating with a door-mounted knob provides a sensor arm on the rotary operator for engaging the door handle to detect closure of the door. A slider may actuate a set of plates capturing a swing arm attached to the rotary operator preventing inadvertent movement of the rotary operator when the door is open.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     BACKGROUND OF THE INVENTION 
     The present invention relates to electrical fuse blocks for mounting in cabinets and having a forwardly-extending, rotary disconnect operator that may engage a handle on the cabinet door when the cabinet door is closed, and in particular to an improvement in such a fuse block that reduces the chance of accidental operation of the disconnect operator when the cabinet door is open. 
     Referring to FIG. 1, a standard fuse block  10  of the prior art may receive fuse cartridges  12  along its front face and may attach at its rear face to the rear wall  14  of a metal cabinet  16 . 
     Input terminals along the top of the fuse block  10  may receive wires  18  which connect independently to one side of each fuse cartridge  12 , the latter which interconnect wires  18  to wires  20  attached to output terminals along the bottom of the fuse cartridge  12 . The wires  18 , for example, may be connected to a source of three-phase power and the wires  20 , for example, may be connected to a motor or other piece of equipment. 
     The fuse block  10  may incorporate a disconnect mechanism (not shown) serving to electrically disconnect the wires  18  from the respective fuse cartridges  12 . The disconnect may be controlled by a rotary operator  22  along one side of the fuse block  12  and extending in an orientation perpendicular to the rear wall  14  of the cabinet  16  toward an open face of the cabinet  16 . 
     The open face of the cabinet may be covered by a door  24  attached by hinges to one side of the cabinet  16 . The door  24  may support a captively mounted rotary handle  26  having an inwardly extending shaft  28 . 
     Referring now to FIG. 2, the handle  26  may include a shaft  28  extending inwardly through an opening in the door  24  and having retaining flanges  30  for retaining it rotatively within that opening. 
     When the door  24  is closed about the cabinet  16 , the shaft  28  of the handle  26  may engage the outermost end of the rotary operator  22  allowing the rotary operator to be operated by the handle  26  when the door  24  is closed on the cabinet  16 . Specifically, an inwardly facing end of the shaft  28  may include a keyway  32  receiving a rectangular end of the rotary operator  22  and a pin  34  extending perpendicularly through the rotary operator. Turning the handle  26 , turns the rotary operator  22  electrically disconnecting or connecting power to wires  20 . 
     Referring again to FIG. 1, while the handle  26  allows disconnection of power to wires  20 , the door  24  on the cabinet  16  is closed. Once the door  24  is open, power may be inadvertently reconnected by counter rotation of the rotary operator  22  which is how exposed. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention modifies a standard fuse block to allow it to sense the position of the door of the cabinet and lock its disconnect in the open position to prevent inadvertent connection of power when the cabinet door is open. The locking of the disconnect may be manually overridden if it is necessary to reconnect power when the cabinet door is open. 
     Specifically, the present invention provides a side mounted lockout positioned proximate to the side face of the fuse block and having a sensing arm having a first end positioned near the outer end of the of the fuse block&#39;s rotary operator. When the door is closed, the sensing arm is pressed inward by engagement of the outer end rotary operator and the door mounted handle. An operator lock communicates with the sensor arm and the rotary operator to lock rotation of the rotary operator except when the sensing arm is depressed. 
     Thus, it is one object of the invention to provide a method of locking fuse blocks of this type against inadvertent actuation when the door is open. 
     It is another object of the invention to provide a locking mechanism that will work with a variety of different cabinet types. Locating the door sensor near the operator, allows the door handle, which necessarily is positioned to engage the rotary operator, to provide the necessary actuation. Modifications to the door or a particular location or orientation of the fuse block within the cabinet are not required so long as the operator of the fuse block properly engages the door handle. 
     The sensing arm may be a sleeve slidably fitting over the rotary operator. 
     Thus, it is another object of the invention to provide for a simple sensing mechanism that is fully supported by the sensing arm to be in alignment with the actuating door handle. 
     The sleeve may include at least one radial extension arm abutting the portion of the door mounted handle when the outer end of the rotary operator is engaged with the portion of the door mounted handle. 
     Thus, it is another object of the invention to provide a door sensor that works with a variety of different door mounted handles so long as some part of the door handle engages the radial arm. 
     The radial extension arm may extend over the front face of the fuse block when the rotary operator is rotated to connect power. Conversely, the radial extension arm may extend along the side face of the fuse block and not over the front face when the rotary arm is rotated to disconnect the fuse to the power connections. 
     Thus it is another object of the invention to provide a visual indication of a connected fuse block, and alternatively, to prevent interference with removal of the fuses by the radial arm when the fuse block is disconnected. 
     The operator lock may include a collar engaging the rotary operator and having at least one tooth captured by a stop communicating with the sensing arm to be retracted when the sensing arm is depressed inward. 
     Thus, it is another object of the invention to provide a locking mechanism that may work with existing fuse block designs by engagement of a collar with the normally rectangular shaft of the rotary operator. 
     The stop may be a slider plate mounted slidably to a support plate fixed with respect to the fuse block, the slider plate sliding along an outwardly extending axis. 
     It is another object of the invention to provide a locking mechanism that may fit closely adjacent to the fuse block so as not to increase the amount of space required within the cabinet for the fuse block. 
     The slider plate and mounting plate may have holes sized to receive the shank of a padlock and aligned when the operator is in the position of disconnecting the fuse. 
     Thus, it is another object of the invention to provide for a positive lockout of the fuse block that cannot be defeated by opening of the cabinet door or manipulating the mechanical operator lock. 
     These particular objects and advantages may apply to only some embodiments falling within the claims, and thus do not define the scope of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a prior art fuse block described above and mounted to the rear of a cabinet and having a forwardly extending rotary disconnect operator that may be received by a door mounted handle when the cabinet door is closed; 
     FIG. 2 is a fragmentary view of the door-mounted handle immediately before engagement with the rotary disconnect operator as known in the prior art; 
     FIG. 3 is a partial cross-sectional view taken along lines  3 — 3  of FIG. 1 showing modification of the prior art fuse block by addition of the door sensing arm and operator lock of the present invention, the sensor arm being a sliding collar engaging a shaft of the door handle to communicate with a slider plate on a mounting plate that provide an operator lock; 
     FIG. 4 a  is a side elevational view of the slider plate and mounting plate of FIG. 3 before closing of the door and pressing down of the sensor collar; 
     FIG. 4 b  is a figure similar to that of FIG. 4 a  showing movement of the slider plate when the door is closed and the sliding collar is pushed down; 
     FIG. 5 is an exploded view of a swing arm fit by a collar onto the rotary disconnect operator of FIG.  3  and interacting with the sliding and mounting plates so as to prevent rotation of the rotary disconnect operator, FIG. 5 further showing the position of a radial extension arm engaging with the door handle when the fuse block is in the disconnected state such as allows easy access to the fuse cartridges; and 
     FIG. 6 is a figure similar to that of FIG. 5 showing the rotation of the radial arms when the fuse block is in the connected state and partially obstructing removal of the fuses as a visual indicator that power is connected. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIG. 3, the present invention modifies the fuse block  10  described above by placing a tubular sleeve  40  about the rotary operator  22  and beneath the pin  34 . The tubular sleeve  40  is sized to move freely up and down the rotary operator  22  limited principally by the pin  34  in upward motion and abutment of the bottom of the tubular sleeve  40  with an activation tab  42  of a slider plate  45  in downward motion, as will be described. 
     Referring now to FIGS. 3 and 5, the upper end of the tubular sleeve  40  is attached to an engagement collar  44  having two radial extension arms  46 . The engagement collar  44  has a square opening fitting closely to the square cross section of the rotary operator  22  so that the engagement collar, radial extension arms, and tubular sleeve  40  rotate with the rotary operator  22  while being free to move up and down along the rotary operator  22 . 
     The engagement collar  44  and radial extension arms  46  are sized to abut an inner face  48  of the shaft  28  of the captive door handle  26  when the door  24  of the cabinet  16  is closed. In this state, the shaft  28  presses down on tubular sleeve  40 . When the door  24  is open (as shown in FIG.  3 ), the tubular sleeve  40  is free to travel upward. The radial extension arms  46  ensure that the shaft  28  will abut the engagement collar  44  for a wide range of handle types and designs. 
     As mentioned above, the lower end of the rotary operator  22  engages one end of a horizontally extending activation tab  42 . The activation tab  42  has contour adjacent to the rotary operator  22  allowing free rotation of the rotary operator  22  while still allowing it to engage the lower end of the sliding tubular sleeve  40 . 
     The activation tab  42  communicates with a vertically mounted slider plate  45  and may be folded out of the same sheet of metal as slider plate  45 . 
     Referring also to FIGS. 4 a  and  5 , slider plate  45  is slidably held against the vertical surface of a mounting plate  56  (on a side of the mounting plate away from the fuse block  10 ) by shoulder rivets  60  affixed to the mounting plate  56  and passing through vertical slots  62  in the slider plate  45 . Mounting plate  56  may be mounted to base plate  58  by means of right angle tabs  59  attached to base plate  58  by fasteners  61  such as machine screws or the like. The base plate  58  is coplanar with the base of the fuse block  10  and the rear wall  14  of the cabinet  16  on which the fuse block  10  is installed. 
     A compression spring  52  is held to the under surface of tab  42  by means of downwardly extending tooth  53  from tab  42 . The compression spring  52  is received by a corresponding upwardly extending tooth  54  from mounting plate  56 . The compression spring  52  thereby urges the slider plate  45 , the activation tab  42 , and hence the lower end of the rotary operator  22  upward absent downward pressure from the shaft  28  of the handle  26  on the door  24 . 
     Referring now to FIGS. 4 b  and  5 , a swing arm  66  may be attached to the rotary operator  22  beneath the sleeve  40  by means of a collar  68  having a square cutout  70  to engage with the square cross-section of the rotary operator  22 . The swing arm  66  attached to the collar  68  extends horizontally through a slot  72  (shown in FIG. 4 b ) in the mounting plate  56 , the slot being sufficient in size to allow approximately 90° of rotation of the rotary operator  22  when the collar  68  engages the rotary operator  22 . An opening  73  in the slider plate  45  allows the swing arm  66  to also extend through the slider plate  45 . 
     When the rotary operator  22  is in the disconnect position, the swing arm  66  is fully counterclockwise against the right side of the slot  72 . In this position, slider plate  45  may be urged upward by the spring  52  to capture an end of the swing arm  66  in a notch  71  in a lower edge of an opening  73  of the slider plate  45 . The notch  71  together with the constraint provided by the lower edge of the slot  72  prevents rotation of the rotary operator  22  when the end of swing arm  66  is so captured. 
     Referring to FIGS. 4 a  and  4   b , a hole  76  in the slider plate  45  and hole  78  in the mounting plate  56  align when the swing arm is held in the notch  71  of the slider plate  45  so that the slider plate  45  can move upward. Passage of the shank of a padlock through both holes  76  and  78  prevents movement of the slider plate  45  with respect to the mounting plate  56  and thus disengagement of the notch  71  from the end of swing arm  66 . Thus, in this location, the swing arm  66  prevents rotation of the rotary operator  22  to reconnect power to the fuse block  10 . 
     Referring now to FIGS. 3 and 4 a , when the door  24  is in the open position, or slightly before being fully closed, as shown in FIG. 3, the tubular sleeve  40  is biased upward by activation tab  42  which in turn is urged upward by a helical compression spring  52 . With further closure of the door, the inner face  48  of the shaft  28  of the door mounted handle  26  presses down on the engagement collar  44  and radial extension arms  46 , in turn pushing tubular sleeve  40  downward which engages with activation tab  42  to push slider plate  45  down as shown in FIG. 4 b.    
     Referring to FIG. 3, with closure of the door and pushing down of the slider plate  45 , slot  72  is uncovered and the end of the swing arm  66  is freed from notch  71 . Thus, when the door  24  is fully shut, swing arm  66  is free to move in a clockwise direction  80  as indicated by arrows in FIGS. 4 b  and  5 . Movement of the swing arm  66  within the slot  72  allows 90° of clockwise rotation of the rotary operator  22  allowing power to be connected to the fuse block  10 . 
     Referring again to FIG. 5, when the swing arm  66  is in the furthest counterclockwise position, for example, locked by slider plate  45 , with power removed from the fuse block  10 , the radial extension arms  46  on engagement collar  44  run generally parallel to the proximate edge of the fuse block  10  providing good access to the fuse cartridges  12 . 
     Normally, when the door  24  is open, the swing arm  66  will be as shown in FIG. 5, power will be disconnected from the fuse block  10 , and the slider plate  45  will be upwardly engaged with the swing arm  66  as shown in FIG. 4 a . The locking mechanism may, however, be overridden by pressing down on the tab  42  when the door is open and rotating the collar and radial extension arms  46  to the position shown in FIG.  6 . 
     When the swing arm  66  is in the furthest clockwise position, as shown in FIG. 6, with power connected to the fuse block  10 , this rotation causes radial extension arms  46  to rotate by 90° and of one of the radial extension arms  46  to extend over part of the fuse block  10  providing a visual indication that it is not appropriate to remove the fuses at this time as power is still connected. 
     It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein, but include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims.