Abstract:
An AC disconnect switch having a first embodiment with an enclosure with portions of its side walls removed for easier access. The first embodiment of the AC disconnect switch also has a cover that is hinged at the top of the case and opens at an angle greater than 180 degrees to further enhance access. In a second embodiment, the cover is reversibly hinged on the side of the case of the enclosure for enhance access. Both embodiments of the AC disconnect switch have the terminal lugs with roughened surfaces on the terminal block aligned in the transverse direction of the enclosure to accommodate precut and prestripped wiring harnesses. The terminal block is mounted to the case by a tab arrangement which requires only a single screw. The AC disconnect switch also has a locking mechanism with retractable hasp to minimize shipping volume.

Description:
FIELD OF THE INVENTION 
     This invention relates to an AC disconnect switch, and more specifically relates to an AC disconnect switch having an enclosure with an internal terminal block assembly that is easily accessible for installation of wiring, that is adaptable to installation in inaccessible locations, and that has an improved locking mechanism. 
     BACKGROUND OF THE INVENTION 
     AC disconnect switches are well-known in the art and are often used for connecting AC current to and disconnecting AC current from air-conditioner compressors. Such AC disconnect switches operate between on and off conditions by inserting a pullout handle assembly into and removing the pullout handle assembly from a stationary terminal block assembly mounted within the enclosure of the AC disconnect switch. The pullout handle assembly has conductive blades which engage stationary stabs within the terminal block assembly to thereby complete an electric circuit. Such AC disconnect switches may or may not incorporate fuses within the pullout handle assembly. 
     Although AC disconnect switches come in a variety of mechanical designs, a typical design is shown in Miller et al. U.S. Pat. No. Re. 34,113. The disclosed AC disconnect switch includes an enclosure comprising a rectangular shaped case with a hinged cover. The cover is hinged on the top but may be hinged on the side. A plastic terminal block is mounted within the volume defined by the case. The terminal block includes terminal lugs to which wires may be connected. The terminal lugs in turn are electrically connected to female jaws or stabs within the terminal block. The female stabs are located within a receptacle formed in the terminal block. A pullout handle assembly is dimensioned to fit within the receptacle and includes knife blades which are electrically interconnected within the handle assembly. When the pullout handle assembly is inserted into the receptacle, the knife blades of the handle assembly engage the female stabs and thereby complete the circuit. An internal plastic shield covers the terminal lugs once installation of the wires has been completed. 
     Other AC disconnect devices are shown in Smith U.S. Pat. No. 2,581,308, Coley et al. U.S. Pat. No. 3,955,709, DiMarco et al. U.S. Pat. No. 4,233,482, Hibbert et al. U.S. Pat. No. 4,675,782, Hibbert et al. U.S. Pat. No. 4,794,211, Reichow et al. U.S. Pat. No. 5,272,297, and Kuki et al. U.S. Pat. No. 5,842,560. 
     The prior art AC disconnect switches have several shortcomings. The most consistent shortcoming of the prior art references is the relative inaccessibility of the terminal block within the case. In practice, AC disconnect switches are often mounted in locations where direct access may be limited. Therefore, it is important that the electrician wiring the AC disconnect switch have easy access from all angles to the terminal block and the terminal lugs of the terminal block. A case with a cover that only opens 90 degrees may often limit easy access to the terminal lugs of the terminal block. In addition, to facilitate wiring, the wiring from the air-conditioner compressor is often provided in the form of a wire harness which has it ends precut to a uniform length and stripped. In order to easily accommodate the preformed wiring harnesses, the terminal lugs should be aligned across the transverse direction of the AC disconnect switch case so that further cutting and stripping of the wires prior to installation is not required. 
     In addition, side opening AC disconnect switches may be mounted so that the location will not accommodate the opening of the cover in one direction. Therefore, an installer may have to maintain an inventory of AC disconnect switches that have both of left-hand opening covers and right-hand opening covers to accommodate particular installation locations. 
     The prior art also discloses AC disconnect switches with a locking mechanism to maintain the cover in a closed position on the case. One particular mechanism disclosed by the prior art is a protruding hasp attached to the case and engaging a slot in the cover. In the prior art, the protruding hasp is an impediment to packaging the AC disconnect switch in a rectangular box and thereby increases shipping volume. 
     In addition to the installation and drawbacks outlined above, the prior art AC disconnect switches are often unnecessarily complicated in their construction, requiring multiple screws for attaching the terminal block to the case and for attaching the cover to the case. 
     SUMMARY OF THE INVENTION 
     The present invention solves the above problems by providing an AC disconnect switch with an enclosure that provides improved access to the terminal block for the installer, improved adaptability to inaccessible installation locations, an improved locking mechanism, and simplified construction. In one embodiment of the present invention with a top opening cover, the case of the AC disconnect switch has portions of its side walls removed thereby exposing the sides of the terminal block for easier access. The AC disconnect switch has a cover that is hinged at the top of the case and opens at an angle greater than 180 degrees to further enhance installation access. In that same embodiment, the cover is provided with a detent mechanism that holds the cover open during wiring installation to further insured easy access for the installer. The AC disconnect switch further has the terminal lugs on the terminal block aligned in the transverse direction of the enclosure case to accommodate precut and prestripped wiring harnesses. The terminal lugs have roughened contact surfaces to insure good electrical contact between the terminal lugs and the wire. The terminal block is mounted to the case by a unique tab arrangement which requires only a single screw, the required ground screw, for installation of the terminal block within the case. The pullout handle assembly has a folding handle which minimizes the depth required for the case of the AC disconnect switch. Moreover, a locking mechanism has a retractable hasp at the bottom of the case that minimizes the shipping volume for the AC disconnect switch. 
     In a second embodiment of the present invention, the cover is hinged on the side of the case. The hinge arrangement requires no screws and instead snaps on and off the case. Consequently, the hinge arrangement allows for the cover to be hinged for either left-hand opening or for right-hand opening. Like the first embodiment, the second embodiment further has a single screw mounted terminal block with inline terminal lugs, roughened terminal lug contact surfaces, a folding handle to minimize depth, and a folding hasp to minimize shipping volume. 
     Therefore, it is an object of the present invention to provide an AC disconnect switch with an enclosure that provides improved access to the terminal block for the installer, improved adaptability to inaccessible installation locations, an improved locking mechanism, and simplified construction. 
     Further objects, features, and advantages will become apparent upon consideration of the following detailed description of the invention when taken in conjunction with the drawing and the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a first embodiment of an AC disconnect switch with top hinges in accordance with the present invention. 
     FIG. 2 is a front elevation view of the first embodiment of the AC disconnect switch (with the cover and the plastic shield removed) in accordance with the present invention. 
     FIG. 3 is a top plan view of the first embodiment of the AC disconnect switch in accordance with the present invention. 
     FIG. 4 is a cross section view of the first embodiment of the AC disconnect switch in accordance with the present invention as seen along line  4 — 4  of FIG. 2 with the cover closed and the terminal block removed. 
     FIG. 5 is a cross section view, similar to FIG. 4, of the first embodiment of the AC disconnect switch in accordance with the present invention with the cover opened. 
     FIG. 6 is a perspective view of the molded terminal block in accordance with the present invention. 
     FIG. 6A is a cross section view of one of the terminal lugs of the molded terminal block of the AC disconnect switch in accordance with the present invention as seen along line  6 A— 6 A of FIG.  6 . 
     FIG. 7 is a perspective view of the pullout handle assembly in accordance with the present invention. 
     FIG. 8 is a cross section view, similar to FIG. 4, of the first embodiment of the AC disconnect switch in accordance with the present invention showing the terminal block mounted within the case of the AC disconnect switch. 
     FIG. 8A is a front elevation view of the plastic shield incorporated into both embodiment of the AC disconnect switch in accordance with the present invention. 
     FIG. 9 is a front elevation view of the first embodiment of the AC disconnect switch in accordance with the present invention with the plastic shield installed and the pullout handle assembly in place. 
     FIG. 10 is a perspective view of a second embodiment of the AC disconnect switch in accordance with the present invention with side hinges. 
     FIG. 11 is a front elevation view of the second embodiment of the AC disconnect switch in accordance with the present invention with the shield and the pullout handle assembly removed. 
     FIG. 12 is a front elevation view of the second embodiment of the AC disconnect switch in accordance with the present invention with the shield and the pullout handle assembly installed. 
     FIG. 13 is a bottom plan view of the second embodiment of the AC disconnect switch in accordance with the present invention with the hasp of the locking mechanism retracted. 
     FIG. 14 is a bottom plan view of the second embodiment of the AC disconnect switch in accordance with the present invention with the hasp of the locking mechanism extended. 
     FIG. 15 is a detailed perspective view of hinge clips used with the second embodiment of the AC disconnect switch in accordance with the present invention. 
     FIG. 16 is a detailed perspective view of hinge clips used with the second embodiment of the AC disconnect switch in accordance with the present invention. 
     FIG. 17 is a detailed perspective view of hinge clips used with the second embodiment of the AC disconnect switch in accordance with the present invention. 
     FIG. 18 is a detailed perspective view of hinge clips used with the second embodiment of the AC disconnect switch in accordance with the present invention. 
     FIG. 19A is a detailed perspective view of the retractable hasp, in the retracted position, used with both embodiments of the AC disconnect switch in accordance with the present invention. 
     FIG. 19B is a detailed perspective view of the retractable hasp, in the extended position, used with both embodiments of the AC disconnect switch in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, in which like reference numerals represent like parts throughout the several views, FIGS. 1 through 9 discloses a first embodiment of an AC disconnect switch  10  with a top hinged cover comprising an enclosure  11  and a terminal block assembly  16 . The enclosure  11  comprises a case  12  with a cover  14 . The terminal block assembly  16  comprises a plastic terminal block  40  and a pullout handle assembly  42 . The terminal block assembly  16  is mounted within the case  12 . The AC disconnect switch enclosure  11  has a transverse direction  13  and a longitudinal direction  15 . 
     The case  12  has side walls  18  and  20 , bottom wall  22 , top wall  24 , and back wall  26 . The cover  14  has side walls  28  and  30 , front wall  32 , bottom wall  34 , and top wall  36 . The cover  14  is hinged by means of a hinge assembly  44  to the case  12  adjacent the top wall  36  of the cover  14  and the top wall  24  of the case  12 . The hinge assembly  44  includes stationary members  46  and  48  that wrap around the side walls  18  and  20  respectively to form channels  50  and  52  (FIGS.  2  and  9 ). As shown in FIGS. 2 and 3, dimples  56 ,  58 ,  60 , and  62  are formed in members  46  and  48  and extend into channels  50  and  52 . Likewise, dimples  64  and  66  are formed in cover side walls  30  and  28  respectively (FIG.  3 ). As shown in FIGS. 4 and 5, the dimple  64  in cover side wall  30  engages matching dimple  62  in stationary member  48 , and likewise dimple  66  in cover side wall  28  engages matching dimple  58  in stationary member  46 . The matching dimples thus form the hinge mechanism  44  for the cover  14  and define the pivot axis for the rotation of the cover  14 . The cover side walls  28  and  30  also have detent dimples, such as dimple  68  in cover side wall  30  (FIG.  5 ). Dimple  68  engages dimple  60  to hold the cover  14  in its open position. Because the case top wall  24  does not extend forward as far as the pivot axis  62  (FIG. 5) of the cover  14 , the cover  14  can rotate greater than 180 degrees as shown in FIG. 5 to allow easy access to the inside of the case  12 . In addition, the detent mechanism of dimples  60  and  68  (FIG. 5) hold the cover  14  in the open position while an electrician wires the AC disconnect switch  10 . 
     Referring to FIG. 5, the top wall  24  of the case  12  has a groove  80  extending along the transverse direction  13 . The top wall  36  of the cover  14  has a matching lip  82  extending along the transverse direction  13 . As can be seen in FIGS. 4 and 8, the lip  82  engages the groove  80  to form a water seal along the top of the enclosure  11 . 
     Referring to FIGS. 1,  3 ,  4 ,  19 A, and  19 B, the cover  14  is locked to the case  12  in the closed position by means of the locking mechanism  17 . The locking mechanism  17  comprises a retractable hasp  200 , which is pivotally attached to the bottom wall  22  by means of a pivot pin  202 . The hasp  200  further has dimples  21  and  23 , an arcuate slot  27 , and a hole  25 . The bottom wall  22  of the case  12  has a threaded standoff  188  as best seen in FIGS. 19A and 19B. The hasp  200  rotates about the pivot pin  202  from its retracted position shown in FIG. 19A to its extended position shown in FIG.  19 B. As the hasp  200  rotates into the extended position (FIG.  19 B), the arcuate slot  27  engages the standoff  188  to stabilize the hasp  200  in the extended position. The dimples  21  and  23  serve to engaged the edge of the bottom wall  22  to hold the hasp  200  in its extended position. With the hasp  200  in its extended position (FIGS.  1  and  4 ), the hasp  200  engages a slot  201  in the cover  14 , and a padlock or other lock can be inserted through hole  25  to secure the cover  14  to the case  12 . The retracted position allows the AC disconnect switch to fit into a smaller shipping box and thus reduce shipping volume. 
     The side walls  18  and  20  of case  12  have cut away sections  70 , and  72 . The side walls  28  and  30  of cover  14  have matching protruding sections  74  and  76 . The cut away sections  70  and  72  of case  12  provide improved access to the inside of the case  12  when the cover  14  is opened. The matching protruding sections  74  and  76  of cover side walls  28  and  30  cover the side wall cut away sections  70  and  72  when the cover  14  is closed. 
     The terminal block assembly  16  includes the molded plastic terminal block  40  (FIG. 6) and the pullout handle assembly  42  (FIG.  7 ). The terminal block  40  has a rectangular receptacle  90  for receiving the pullout handle assembly  42 . The terminal block also has slots  91 ,  92 ,  93 ,  94 ,  95 ,  96 ,  97 , and  98  in the base  100  of the receptacle  90 . Terminal lugs  105 ,  106 ,  107 , and  108  are press fit into the terminal block  40 . Each terminal lug has a set screw, a connector, and a stab. As shown in FIGS. 2 and 6, terminal lug  105  has a set screw  110 , a connector  112 , and a stab  114  located within slot  91 . Terminal lug  106  has a set screw  116 , a connector  118 , and a stab  120  located within slot  94 . Terminal lug  107  has a set screw  122 , a connector  124 , and a stab  126  located within slot  96 . Terminal lug  108  has a set screw  128 , a connector  130 , and a stab  132  located within slot  97 . With reference to FIG. 6A, a detail of terminal lug  108  is shown. The connector  124  of the terminal lug  108  has a roughened surface  33 . The set screw  128  captures a wire  31  against the roughened surface  33  to ensure good electrical contact and to securely hold the wire  31  from being pulled out of the terminal lug  108 . 
     Returning to FIG. 6, the terminal block  40  has side hold down tabs  134  and  136  and front hold down tab  138 . As can be seen in FIGS. 2 and 8, dimples  140  and  142  and dimples  144  and  146  are formed in the case side walls  18  and  20 , respectively. The side hold down tabs  134  and  136  slide under dimples  140  and  142  and dimples  144  and  146 , respectively. The dimples  142  and  146  abut stops  148  and  150  to limit movement of the terminal block  40  in the longitudinal direction  15  toward the top wall  24  of the case  12 . A ground terminal lug  152  (FIG. 2) engages the front hold down tab  138  and is connected to the back wall  26  of the case  12  by means of a single terminal block screw  154 . 
     Turning to FIG. 7, the pullout handle assembly  42  has knife blades  161 ,  162 ,  163 , and  164 . The knife blades are aligned to mate with the pattern for slots  91 ,  92 ,  93 ,  94 ,  95 ,  96 ,  97 , and  98  in the terminal block  40 . Knife blades  161  and  162  are electrically connected by connector  166 , and knife blades  163  and  164  are electrically connected by connector  168 . FIG. 9 shows the pullout handle assembly  42  installed in the receptacle  90  of the terminal block  40  in the “on” position. In the “on” position, the knives  164  and  163  engage stabs  91  and  94  to connect the line and load on one side to the terminal block  40 . Likewise, in the “on” position, the knives  161  and  162  engage stabs  97  and  96  to connect the line and load on the other side to the terminal block  40 . In order to disconnect the line from the load, the pullout handle assembly  42  is pulled out of the receptacle  90 , rotated 180 degrees, and reinserted so that the knives  161 ,  162 ,  163 , and  164  engage empty slots  92 ,  93 ,  95 , and  98  (FIG.  2 ). The pullout handle assembly  42  has indices “on” and “off” imprinted on its face to indicate to the installer whether the pullout handle assembly  42  is inserted with the circuit on or off. 
     Turning to FIG. 9, the pullout handle assembly  42  has a handle bracket  172  with holes at each end. A folding handle  170  comprises a wire bent in the shape of a “C”. The ends of the handle  170  engage the holes in the bracket  172  so that the handle  170  can pivot from an extended gripping position to a retracted storage position as shown in FIG. 9 in order to minimize the depth required for the case  12 . 
     FIGS. 1 and 2 show the terminal block assembly  16  mounted in the case  12 . The terminal set screws  110 ,  116 ,  122 , and  128  are aligned in the transverse direction  13 . Consequently, a precut and prestripped wiring harness can be connected to the terminal lugs without recutting or restripping the wires. Once the terminal block assembly  16  is in place as shown in FIGS. 1 and 2, a plastic shield  180  is placed over the terminal block assembly  16  to preclude contact by an installer with the terminal lugs  105 ,  106 ,  107 , and  108  when the cover  14  is opened. The plastic shield  180  is held in place by means of buckles  174  and  176  located on the terminal block  40  (FIG.  6 ). The plastic shield  180  (FIG. 8A) has matching tabs  184  and  182  which engage the buckles  174  and  176  from the bottom. A shield screw  186  engages the threaded standoff  188  on the bottom wall  22  of the case  12  and thereby holds the plastic shield  180  in place. 
     A second embodiment of the invention is shown in FIGS. 10 through 18. The second embodiment of the AC disconnect switch  210  is similar to the first embodiment except for the construction of the case  212 , the cover  214 , and the hinge assembly  244 . Particularly, in the second embodiment of AC disconnect switch  210 , the case  212  has side walls  218  and  220 , bottom wall  222 , top wall  224 , and back wall  226 . The cover  214  has side walls  228  and  230 , front wall  232 , bottom wall  234 , and top wall  236 . The cover  214  is hinged by means of a hinge assembly  244  to the case  212  adjacent the cover side wall  230  and the case sidewall  220 . The hinge assembly  244  includes hinges  250  and  252 . The hinge  250  and  252  are identical, and for convenience only the hinge  250  will be described. The hinge  250  includes a hinge clip  260 , a slot  262  in cover side wall  230 , and mounting protrusions  264  and  266  on case side wall  220 . The hinge clip  260  is U-shaped and has legs  270  and  272  that held together by the resilient nature of the material from which the hinge clip is formed. Leg  270  has a transverse channel  275 . Leg  272  has holes  274  and  276 . 
     The installed hinge  250  is shown in FIGS. 17 and 18. The leg  270  with channel  275  engages slot  262  of cover side wall  230  to provide the pivot mechanism for the hinge  250 . The leg  272  is mounted to the case side wall  220  by means of the holes  274  and  276  engaging the protrusions  264  and  266 . The hinge  250  is assembled as shown in FIGS. 15 and 16. First, the slot  262  of cover  214  is aligned with the protrusions  264  and  266 . The hinge clip  260  is then positioned as shown in FIGS. 15 and 16. The leg  270  of the hinge clip  260  is then inserted into the slot  262  of the cover side wall  230 . The hinge clip  260  is then pushed down onto the case side wall  220  and the legs are spread until the holes  274  and  276  engage the protrusions  264  and  266 . 
     By providing slots, such as slot  262 , in both side walls  228  and  230  of the cover  214  and by providing protrusions, such as protrusions  264  and  266 , in both side walls  218  and  220  of the case  212 , the cover  214  can be hinged by means of the hinge clip on either the right or left hand side of the case  212 . Consequently, the second embodiment of the AC disconnect switch  210  provides a reversible door hinge to accommodate a locations which may limit access from one side or the other. 
     The top wall  224  of the case  212  has a groove  280  extending along the transverse direction  13 . The top wall  236  of the cover has a matching lip  282  extending along the transverse direction  13 . When the cover  214  is closed, lip  282  engages the groove  280  to form a water seal along the top of the case  212 . In order for the lip  282  to override the groove  280  when the cover  214  is closed, the hinges, such as hinge  250  provides for longitudinal movement of the cover  214  with respect to the case  212 . The longitudinal movement is provided by the slots, such as slot  262 , being longer than the width of the legs, such as leg  270  (FIG.  18 ). The length of the slots allows the cover  214  to move in the longitudinal direction  15  with respect to the case  212 . 
     While this invention has been described with reference to preferred embodiments thereof, it is to be understood that variations and modifications can be affected within the spirit and scope of the invention as described herein and before and as described in the appended claims.