Abstract:
A locking mechanism for a box having a cover and a base hingeably connected to each other. The locking mechanism comprises a cover latching mechanism and a base latching mechanism. The cover latching mechanism is in a latching position. The two latching mechanisms are in latching engagement with each other to lock the box closed. An unlatching mechanism is provided which is activated to place the latching mechanism in an unlatching position to disengage the latching mechanisms from each other and unlock the box. An activating mechanism to active the unlatching mechanism. A deactivating mechanism is provided to return the cover latching mechanism back to its latching position so that closing the cover will cause the latching mechanisms to become in locking engagement with each other to lock the box. A box opening assembly in the box which is adapted to open the cover as soon as the latching mechanisms are disengaged from each other.

Description:
FIELD OF THE INVENTION 
     The present invention relates to locking mechanisms and more particularly to a locking mechanism for automatically locking boxes for electrical components, such as junction boxes. 
     BACKGROUND 
     Junction boxes usually have a cover and a base which are hinged together. It often happens that the cover is closed over the base but is left unlocked. This may permit access to the interior of the unlocked box by people and animals and/or may permit water, dust, etc. to enter the box, thereby possibly causing damage to the components therein. In addition, such boxes are often made without handles which makes it difficult to pry open the box. 
     It is therefore desirable to provide an automatic locking mechanism for such boxes which would require a tool to open the box but which would not require a tool to lock the box. The box would automatically lock as soon as the cover is closed. It is also desirable to provide a mechanism which would open the box as soon as the cover is unlocked. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes these difficulties and provides an improved locking mechanism for a box which will ensure that the box is automatically locked as soon as the cover is closed and which will automatically open the cover when the box is unlocked. The automatic locking mechanism may comprise a pair of resilient latch arms with a lock prong at the end of each. The lock prongs will automatically enter into retaining grooves when the cover is closed to lock the box. A control cam is provided adjacent to the latch arms which is rotated to spread the latch arms and move the lock prongs out of the retaining grooves thereby unlocking the box and permitting the cover to be opened. A spring may be positioned under the cover so that as soon as the box is unlocked the cover will pop open. After the box is unlocked, the control cam is released and a wind-up spring is provided to rotate the control cam away from the latch arms so that the latch arms can assume their original position. When the cover is closed, the lock prongs on the latch arms will again enter the retaining grooves to automatically lock the box. 
    
    
     DRAWINGS 
     A preferred embodiment of the invention has been chosen for purposes of illustration and description and is shown in the accompanying drawings forming a part of the specification wherein: 
     FIG. 1 is a diagrammatic view of a box made in accordance with the present invention. 
     FIG. 2 is a diagrammatic and schematic interior view of the box as seen from line  2 — 2  of FIG. 1 showing the position of the parts when the box is closed. 
     FIG. 3 is a diagrammatic and schematic interior view of the box as seen from line  3 — 3  of FIG.  2 . 
     FIG. 4 is an enlarged fragmentary view partly in section of the locking assembly of the present invention showing the position of the parts when the box is closed. 
     FIG. 5 is an enlarged sectional view taken along line  5 — 5  of FIG.  4 . 
     FIG. 6 is an enlarged sectional view taken along line  6 — 6  of FIG.  4 . 
     FIG. 7 is a diagrammatic and schematic interior view of the box similar to FIG. 2 showing the position of the parts when the box is open. 
     FIG. 8 is a diagrammatic and schematic interior view of the box as seen from line  8 — 8  of FIG.  7 . 
     FIG. 9 is an enlarged fragmentary view partly in section of the locking assembly of the present invention showing the position of the parts when the box is open. 
     FIG. 10 is an enlarged sectional view taken along line  10 — 10  of FIG.  9 . 
     FIG. 11 is an enlarged sectional view taken along line  11 — 11  of FIG.  9 . 
     FIG. 12 is an exploded view of the control mechanism for the locking assembly of the present invention. 
     FIG.  13 . is a plan view of the control bolt used in connection with the present invention. 
     FIG. 14 is a sectional view taken along line  14 — 14  of FIG.  13 . 
     FIG. 15 is a sectional view taken along line  15 — 15  of FIG.  12 . 
     FIG. 16 is a side elevational view of the wind-up spring used with the present invention. 
     FIG. 17 is a top view thereof. 
     FIG. 18 is a side elevational view of the control cam used in the control mechanism of the present invention. 
     FIG. 19 is a top view thereof. 
     FIG. 20 is a side elevational view partially in a section of the pop-up spring assembly used with the present invention. 
     FIG. 21 is a sectional view showing the holding plate of the pop-up spring. 
     FIG. 22 is a top view thereof. 
     FIG. 23 is a plan view of the pop-up spring. 
    
    
     DESCRIPTION 
     Referring to the drawings, the junction box  1  in which the present invention is used comprises a base  2  and a cover  3  attached to the base  2  by means of a hinge assembly  4 . As shown in FIGS. 1 to  3 , the base  2  has front and rear walls  5  and  6 , respectively, a pair of side walls  7  and a bottom panel  8  from which the walls  5 ,  6  and  7  extend at substantially right angles thereto and which terminates an upper edge  9 . The cover  3  is provided with front and rear walls  10  and  11  respectively, a pair of side walls  12 , and a top panel  13  from which the walls  10 ,  11  and  12  extend at substantially right angles thereto. 
     Adjacent to the front wall  5 , the base  2  is provided with an upstanding latch column  15  on latching assembly. The latch column  15  extends from the bottom panel  8  (on which it is mounted) up to approximately the upper edge  9  of the walls  5 ,  6  and  7 . However, it will be understood that the height of this latch column  15  may be changed without departing from the invention. The latch column  15  has an upper edge  16  (substantially at the same level as the upper edge  9  of the base  2 ), opposed side walls  17  and opposed front and rear walls  19 . Slightly below its upper edge  16 , the latch column  15  is provided with a pair of opposed retaining grooves  18  extending inwardly from each side wall  17  thereof and preferably extending for the entire depth of the latch column  15  between front and rear walls  19 . In the drawings, the retaining grooves  18  have been shown as being substantially v-shaped. However, it will be understood that the retaining grooves  18  may assume any desired shape. 
     Best shown in FIG. 4, the cover  3  is provided with a locking assembly or latching mechanism  20  depending from the top panel  13  and adjacent to the front wall  10  thereof in overlying relationship to the latch column  15 . The locking assembly  20  comprises a pair of spaced and substantially parallel latch arms  21  extending downwardly from the top panel  13  of the cover  3  at substantially right angles thereto to a position below the upper edge  9  of the base  2 . In the drawings, the latch arms  21  are shown as being integral with and extending downwardly from the top panel  13 . However, it will be understood that, if desired, the latch arms  21  may be a separate unit mounted on the cover  13 . Each latch arm  21  has lock prong  22  extending inwardly from its lower end which is adapted to enter into latching engagement with the retaining grooves  18  in the latching column  15  to lock the cover  3  onto the base  2  and keep the box  1  closed. Preferably, the lock prongs  22  are substantially the same shape as the retaining grooves  18  in the latching column  15 . The latch arms  21  are resilient so that if they are spread apart and then released, they will snap back to their original perpendicular and parallel latching position shown in FIG.  2 . 
     A control cam or unlatching mechanism  25 , best shown in FIGS. 12,  18  and  19 , is provided to control the position of the latch arms  21 . The control cam  25  will spread the latch arms  21  apart (FIGS. 7,  8 ,  9  and  11 ) when rotated in one direction to move each lock prong  22  out of its retaining groove  18  to disengage the latch arms  21  from the latch column  15  which will release the cover  3  and permit it to be opened relative to the base  2 . When the control cam  25  is rotated in the opposite direction, (FIGS. 2,  3 ,  4  and  6 ) the latch arms  21  will snap back and resume their original perpendicular and parallel latching position. With the latch arms  21  in this position, as soon as the cover  3  is closed, the latch arms  21  are placed into latching engagement with latch column  15  and the lock prongs  22  will snap into retaining grooves  18  thereby automatically locking the box  1  in its closed position. 
     Best shown in FIGS. 18 and 19, the control cam  25  comprises a central body  45  and a pair of cam faces  46  extending diametrically outwardly therefrom. The diameter of the central body  45  is less than the distance between the latch arms  21  when they are at rest (see FIGS. 2,  3 ,  4  and  6 ) and not contact nor affect the position of the latch arms  21 . However, the distance between its cam faces  46  is greater than the distance between the latch arms  21  so that when the control cam  25  is rotated the cam faces  46  are turned 90 degrees and strike the latch arms  21  to move them outwardly until the lock prongs  22  are moved out of the retaining grooves  18  (FIGS. 7,  8 ,  9  and  11 ) thereby unlocking the cover  3  and permitting it to be opened. When the control cam  25  is rotated, back to its original position, cam faces  46  are moved back to the position in FIGS. 2,  3 ,  4  and  6 , and since the latch arms  21  are no longer being spread apart by the cam faces  46 , they will snap back into their original parallel and perpendicular position of FIGS. 2,  3 ,  4  and  6 . The control cam  25  has a circular control opening  48  with female arms  49  extending diametrically therefrom. The control cam  25  also has a spring anchor hole  47  therein spaced from the central body  45  for a purpose which will be discussed in greater detail hereinbelow. 
     A control bolt  26 , as shown in FIGS. 13 and 14, is provided to control the position of the control cam  25 . The control bolt  26  comprises the usual hexagonal head  27 , an integral support ring  29  therebelow, an elongated circular body portion  28  and a threaded free end  31 . The control bolt  26  may be a security type bolt having a hexagonal head  27  that requires a special security tool to engage or disengage the bolt, generally known to one skilled in the art (not shown). The control bolt  26  has a pair of diametrically opposed elongated keys  30  extending length-wise from diametrically opposed sides of its body portion  28 . As shown in FIGS. 2 and 4, the cover  13  preferably has a counter-sunk area  33  providing a support ledge  34  below the surface of the cover  13 . Best shown in FIG. 15, the ledge  34  has an opening  35  therein which comprises a circular center portion  36  and diametrically opposed spaced arcuate side portions  37 . As shown in FIGS. 5 and 10, the center portion  36  has curved edges  38  which conform to the curvature of the body portion  28  of the bolt  26 . The arcuate side portions  37  have curved outer edges  39  with stop end edges  40 . The diametrical distance between the curved outer edges  39  is substantially equal to the diametrical distance between the keys  30 . A spring anchor hole  41  is provided in the support ledge  34  spaced from the bolt-receiving opening  35 . 
     As shown in FIGS. 4 and 9, the control bolt  26  extends through opening  35  in support ledge  34  with its main body portion  28  seated in the center  36  and its two keys  30  extending into the arcuate side portions  37 . The support ring  29  rests on the support ledge  34  with the top of the head  27  below the level of the top panel  13  of cover  3 . When the control bolt  26  is rotated, the stop end edges  40  in the arcuate side portions  37  will limit rotation of the bolt  26  to a ninety degree angle in either direction. The control bolt  26  also enters the opening  48  in the control cam  25  with its keys  30  extending into the female arms  49  so that when the bolt  26  is rotated the cam  25  will also rotate. With this arrangement when the bolt is rotated in one direction the control cam  25  is rotated 90 degrees causing its cam faces  46  to strike the latch arms  21  to spread them apart and move the lock prongs  22  out of the retaining grooves  18  (as shown in FIGS. 7,  8 ,  9  and  11 ). When the control cam rotates back to its original position its cam faces  46  move away from the latch arms  21  so that they may return to their original positions (as shown in FIGS. 2,  3 ,  4  and  6 ). 
     A wind-up spring  50 , best shown in FIGS. 16 and 17, is provided for automatically rotating the control cam  25  back to its original position after the torque on the control bolt  26  is released. The wind-up spring  50  is a coil spring having upper and lower anchoring legs  51  and  52 . As shown in FIGS. 4 and 9, the upper anchoring leg  51  is inserted in the anchor hole  41  in the support ledge  34  and the lower anchoring  52  is inserted into the anchor hole  47  in the control cam  25 . The wind-up spring  50  is not normally under tension (see FIG.  4 ). However, when the control cam  25  is rotated in one direction by the control bolt  26  (in order to turn its cam faces  46  90 degrees and to spread the latch arms  21  apart), as shown in FIG. 9, the spring  50  is wound up against its normally unwound condition. Once the torque on the control cam  25  is released (by releasing the control bolt  26 ) the spring  50  will unwind itself and resume its original position thereby automatically turning the control cam  25  back to its original position and permitting the latch arms  21  to return to their original position, as shown in FIG.  4 . 
     The locking mechanism of the present invention may also include an automatic box opening or pop-up assembly  60  for opening the cover  3  once the latch arms  21  are spread apart to release the cover  3 . Best shown in FIG. 20, this pop-up assembly  60  comprises a pop-up spring  61  mounted in and depending from a cap  62  which is attached to the free end  31  of the central bolt  26  by a threaded nut  63 . The cap  62  holds the spring  61  in place in a position to overlie the latch column  15  as shown in FIGS. 4 and 9. Best shown in FIGS. 21 and 22, the cap  62  has an opening  64  with side portions  66  extending diametrically therefrom through which the body portion  28  and keys  30  of the control bolt  26  extend. As shown in FIG. 4, when the cover  3  is closed, the lower edge  65  of the spring  61  will contact the top edge  16  of the latch column  15  and be compressed. As soon as the latch arms  21  are spread apart and the cover  3  is released and free to open, the compression on the spring  61  is released and the spring  61  will expand upwardly to open the cover  3  as shown in FIG.  9 . While for convenience, the pop-up assembly  60  has been shown as being located axially with the locking assembly  20 , it will be understood that the pop-up assembly  60  can be placed elsewhere in the box without departing from the invention. 
     In operation, when the cover  3  is closed, the latch arms  21  have their lock prongs  22  positioned in the retaining grooves  18  to hold the cover  3  down. In this position, the pop-up spring  61  is in its compressed position against the upper edge  16  of the latch column  15  and the control cam  25  is in its inactive position (FIGS. 4 and 6) so that it has no effect on the latch arms  21 . However, when the control bolt  26  is rotated, the control cam  25  is rotated 90 degrees in one direction to its unlatching position where its cam faces  46  strike the latch arms  21  to spread them apart and to move the lock prongs  22  out of the retaining grooves  18  (FIGS.  9  and  11 ). This not only releases the cover  3 , but also winds-up the wind-up spring  50  and causes the pop-up spring  61  to expand upwardly to automatically open the cover  3 . As soon as the torque on the bolt  26  is released the tension on the wind-up spring  50  is also released and the spring  50  unwinds itself back to its original position, thereby rotating the control cam  25  in the opposite direction and moving it back to its original position to free the latch arms  21  from the force of the cam faces  47  and to permit the latch arms  21  to spring back to their original latching position (FIGS.  4  and  6 ). When the cover  3  is closed, the lock prongs  22  of the latch arms  21  will strike latch column  15  and flex out slightly as they slide over the top  16  and along the sides  17  of the latch column  15  until the lock prongs  22  snap into the retaining grooves  18  thereby locking the cover  3  closed. At the same time, the pop-up spring  61  is compressed onto the top  16  of latch column  15  and is ready to pop the cover  3  open when the latch arms  21  are released at a later time. 
     It will thus be seen that the present invention provides an automatic locking mechanisms for a junction box which requires a tool to open the box but which would automatically lock the box when the cover is closed without the use of a tool and which will automatically open the box once the cover is unlocked and released. 
     As many varied modifications of the subject matter of this invention will become apparent to those skilled in the art from the detailed description given hereinabove it will be understood that the present invention is limited only as provided in the claims appended hereto.