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CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 61/897,468 filed Oct. 30, 2013, which is hereby incorporated by reference in its entirety. 
    
    
     FIELD OF INVENTION 
     The present invention relates to a door sequencer. 
     BACKGROUND 
     In order to comply with various local, state and federal safety regulations, cabinets enclosing certain volatile chemicals must be maintained in a properly closed position. The cabinets protect the chemicals from heat during a fire. These cabinets may be referred to as “safety cabinets.” Typically, doors of these cabinets must be closed in a proper sequence in order for the doors to be properly closed. Unfortunately, workers may forget to fully close the cabinet, or the workers will close the cabinet in an improper manner, which may lead to violation of the safety regulations. 
     SUMMARY 
     A door sequencer is described. The door sequencer automatically closes the doors of a cabinet, such as doors of a safety cabinet, in a correct order. The door sequencer promotes compliance with safety regulations. Typical safety cabinets include a first door and a second door and are designed such that one of the doors, for example, the first door, must close before the second door. This provides for proper sealing of the doors. The door sequencer includes a toggle that only permits the second door to close after the first door has already closed. A first spring assembly is engaged to the first door to cause the first door to close. A second spring assembly is engaged to the second door to cause the second door to close. When the first door closes, the first spring assembly contacts the toggle, to change the position of the toggle, which permits the second door to close. The toggle blocks the second door from closing until the first door has closed. 
     In one aspect, a cabinet with a door sequencer is described. The cabinet includes a first door and a second door to close an opening of the cabinet. A first gas spring includes a first extension end and a first base end. A first cable is engaged to the first door and to the first extension end. A second gas spring includes a second extension end and a second base end. A striker is fixedly engaged to the second door. A second cable is engaged to the striker of the second door and to the second extension end. A toggle is engaged to the cabinet, wherein the toggle is movable between blocking and closing positions with respect to the striker. 
     In another aspect a door sequencer is described. The door sequencer includes a first spring assembly. The first spring assembly includes a first gas spring, a first cable, and a first pulley. A second spring assembly includes a second gas spring, a second cable, and a second pulley. A cam assembly includes a housing, a toggle, a striker. The toggle pivots between a first position to block the striker and a second position to allow movement of the striker. Either the first or the second gas spring engages the toggle to cause the toggle to move to the second position. 
     In another aspect, a cabinet with a door sequencer is described. The cabinet includes a first door and a second door to close an opening of the cabinet. The first door and the second door are hingedly engaged to the cabinet. A first gas spring includes a first extension end and a first base end. A first cable is engaged to the first door and to the first extension end. A second gas spring includes a second extension end and a second base end. A striker is fixedly engaged to the second door. A second cable is engaged to the striker of the second door and to the second extension end. A shuttle is engaged to the first extension end. A toggle is engaged to the cabinet. The toggle blocks the closing of the second door until the shuttle contacts the toggle and causes the toggle to pivot or rotate out of the way of the striker. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a view of the door sequencer installed on the cabinet. 
         FIG. 2  is an exploded view of the door sequencer. 
         FIG. 3  is a top down view of the door sequencer installed on the cabinet with the doors closed. 
         FIG. 4  is a top down view of the door sequencer installed on the cabinet with the second door fully opened. 
         FIG. 5  is a top down view of the door sequencer installed on the cabinet with both doors fully opened. 
         FIG. 6  is a top down view of the door sequencer installed on the cabinet with the second door held open by the toggle. 
         FIG. 7  is a top down view of the door sequencer installed on the cabinet with the striker contacting the toggle. 
         FIG. 8  is a top down view of the door sequencer installed on the cabinet with the doors closed. 
     
    
    
     DETAILED DESCRIPTION OF INVENTION 
     With reference to  FIGS. 1-8 , a cabinet  10  is shown. The cabinet  10  includes a first door  20  and a second door  30 . The first and second doors  20 ,  30  are hingedly connected to the cabinet  10 . The cabinet  10  and the first and second doors  20 ,  30  incorporate a door sequencer  40 . The door sequencer  40  automatically closes the first and second doors  20 ,  30  in the proper sequence. 
     The first and second doors  20 ,  30  cover an opening  12  and an interior  14  of the cabinet  10 . The first door  20  includes a flange  25 . In order for the cabinet  10  to properly close, the first door  20  must close before the second door  30 . The second door  30  closes over the flange  25  of the first door  20 , which generally seals the cabinet  10  closed. In the aspect shown in  FIGS. 1-8 , the first door  20  is on a left side of the cabinet  10  and the second door  30  is on a right side of the cabinet  10 . Of course, the order of the doors  20 ,  30  closing and their engagement to the door sequencer  50  may be reversed, i.e., the second door  30  may close first. 
     The door sequencer  40  includes a first spring assembly  150 , which includes a first gas spring  50 . The door sequencer  40  also includes a second spring assembly  170 , which includes a second gas spring  70 . The first gas spring  50  is compressed when the first door  20  is opened, such as by an operator pulling on or opening the first door  20  to access the interior  14  of the cabinet  10 . Likewise, the second gas spring  70  is compressed when the second door  30  is opened. In the exemplary arrangement shown in  FIGS. 1-8 , the second door  30  is opened prior to the first door  20 . The second door  30  includes the door handle and also covers the flange  25  of the first door  20 . Once the doors  20  and  30  are opened, the door sequencer  40  prevents the second door  30  from closing before the first door  30  closes. After the operator releases the first door  20 , the force of the first gas spring  50 , expanding back to its relaxed or extended position, biases or pulls the first door  20  toward the closed position. Likewise, after the operator releases the second door  30 , the force of the second gas spring  70 , expanding back to its relaxed or extended position, biases or pulls the second door  30  toward the closed position. 
     A cam assembly  100  ensures that the first door  20  closes before the second door  30  closes. The cam assembly  100  generally includes a housing  120 , a toggle  140 , and a striker  160 . The striker  160  is pivotally mounted to the second door  30 . The housing  120  may be mounted to the cabinet  10 , such as on a top surface of the cabinet  10  or it may be built into the upper portions of the cabinet  10 . 
     The toggle  140  is rotatably or pivotally mounted to the housing  120 . The toggle  140  includes a catch  170 . The catch  170  stops the travel of the striker  160 —and thus the travel of the second door  30 . The toggle  140  rotates relative to an axis  145 . The toggle  140  may rotate just enough such that the catch  170  is movable out of the way of a locking surface  165  of the striker  160 . The axis  145  is engaged to an upper surface  122  and a lower surface  124  of the housing  120 . The axis  145  is generally stationary relative to the housing  120 . The toggle  140  may rotate approximately 15 degrees to approximately 90 degrees relative to the axis  145 . 
     As shown in  FIG. 4 , the striker  160  includes the locking surface  165  that engages the catch  170 . The catch  170  may physically stop the inward movement of the striker  160 . The catch  170  is positioned between the upper surface  122  and the lower surface  124  of the housing  120 . As the striker  160  moves inward, the locking surface  165  strikes the catch  170 , which stops the closing of the second door  30 . The catch  170  may include a member, such as a rod, bolt, or other structure that lockingly engages to the locking surface  165  of the striker  160 . The locking surface  165  may include a bend, corner, or other engaging member that engages the catch  170 . The catch  170  prevents the locking surface  165  of the striker  160  from moving further toward the interior  14  of the cabinet  10 . As such, the catch  170  stops the closing of the second door  30 . When the toggle  140  rotates, the catch  170  is moved out of the way of the locking surface  165  of the striker  160 . This allows the second door  30  to fully close. 
     With reference to  FIG. 4 , a first cable  55  connects the first door  20  to the first spring  50 . With reference to  FIG. 4 , a second cable  75  connects the striker  160  to the second gas spring  70 . The first cable  55  and the second cable  75  pull the first door  20  and the second door  30 , respectively, to the closed positions. In greater detail, the striker  160  is pivotally and fixedly engaged to the second door  30 . The striker  160  may be connected to an interior surface of the second door  30 . The second cable  75  attaches to the striker  160 . As shown in  FIG. 4 , the second cable  75  attaches directly to a leading end  163  of the striker  160 . When the first door  20  is opened, the first cable  55  urges an extension end  54  of the first gas spring  50  into a base end  52  of the first gas spring  50  (against the force of the first gas spring  50 ). The first cable  55  pulls on the extension end  54  of the first gas spring  50  in a direction generally opposite to an extension direction of the first gas spring  50 . This compresses the first gas spring  50 . The first cable  55  is positioned generally parallel to a length of the first gas spring  50 . When the user lets go of the first door  20 , the first gas spring  50  extends and pulls the first door  20  closed via the first cable  55 . Similarly, the second cable  75  is positioned generally parallel to a length of the second gas spring  70  and pulls the second door  30  closed. 
     The first gas spring  50  and the second gas spring  70  may include a gas spring. A suitable gas spring includes the GENESIS brand spring commercially available from Austin Hardware of Lee Summit, Missouri. Gas springs return to their relaxed state in a slower manner than other types of springs, which helps prevent the doors  20 ,  30  from abruptly slamming closed. The first gas spring  50  includes the base end  52  and the extension end  54 . During application of a compression force to the first gas spring  50  by the operator, such as by opening the door  20 , the first cable  55  pulls the extension end  54  toward the base end  52  compressing the first gas spring  50 , the extension end  54  retracts into the base end  52 , and thus shortens the overall length of the first gas spring  50 . When the compression force on the first gas spring  50  is no longer present, the extension end  54  returns or extends to its fully extended state, which is its relaxed position  50 , and pulls the first door  20  closed via the first cable  55 . In other aspects, different types of spring members, such as mechanical springs, may be employed. 
     Due to the toggle  140 , the second door  30  cannot close until the first door  20  is already closed. The closing of the first door  20  causes the toggle  140  to rotate out of the way of the striker  160 . Specifically, as the first gas spring  50  extends, a shuttle  60  engaged to the first gas spring  50  contacts or pushes the toggle  140  to cause it to rotate about the axis  145 . A leading end  62  of the shuttle  60  strikes a roller  142  attached to the toggle  140 , causing the toggle  140  to pivot on its axis  145 . The toggle  140  pivots out of the way of the striker  160 , which permits the second door  30  to close. The toggle  140  pivots between a blocking position and a closing position. In the blocking position, the catch  170  stops the striker  160  and the second door  30 . In the closing position, the catch  170  is moved out of the way of the striker  160 , and the second door  30  may close. 
     The first gas spring  50  and the second gas spring  70  are generally aligned in opposite directions, i.e., the extension end  54  of the first gas spring  50  is positioned next to the base end  72  of the second gas spring  70 . Likewise, the extension end  74  of the second gas spring  70  is positioned next to the base end  52  of the first gas spring  50 . 
     The first spring assembly  150  generally includes the first gas spring  50 , a first spring housing  51 , the first cable  55 , a first pulley  59 , a track  53 , and the shuttle  60 . The first spring housing  51  holds the base end  52  of the first gas spring  50 . The first spring housing  51  includes a spring  56  that biases the base end  52  of the first gas spring  50  in the direction of extension of the extension end  54 . A plug  63  is positioned in the internal diameter of the spring  56 . The plug  63  and the spring  56  are generally positioned in the interior of the first spring housing  51 . A nut  65  connects the base end  52  of the first gas spring  50  to the plug  63 . The base end  52  has a larger external diameter  67  than the plug  63 . The external diameter  67  presses against the spring  56  in order to compress the spring  56 . The plug  63  helps to maintain the shape of the spring  56  and prevent the spring  56  from tangling. The plug  63  also provides a limit to the compression of the spring  56 . The spring  56  also reacts faster than the first gas spring  50 , and pushes the base end  54  to increase an overall length of the first spring assembly  150  in order to reduce slamming of the first door  20 . The spring  56  helps to maintain tension on the first cable  55  to prevent tangling of the first cable  55 . A first end  57  of the first cable  55  attaches to a bracket  26  on an interior side of the first door  20 . A second end  58  of the first cable  55  attaches to the shuttle  60 . The shuttle  60  fixedly engages the extension end  54  of the first gas spring  50 . 
     The extension of the extension end  54  of the first gas spring  50  moves the shuttle  60 , as the first cable  55  connects the extension end  54  of the first gas spring and the shuttle  60 . The shuttle  60  is movably mounted to the track  53 . As shown in  FIG. 4 , the extension end  54  is engaged to the shuttle  60 . When the first door  20  is allowed to close, the extension of the extension end  54  of the first gas spring  50  pulls the door  20  closed and moves the shuttle  60  to contact the toggle  140 , which allows the second door  30  to close. As the first door  20  is almost closed or already moving to the closed position before the shuttle  60  contacts the toggle  140 , the first door  20  closes before the second door  30 . 
     The second spring assembly  170  includes the second gas spring  70 , a second spring housing  71 , the second cable  75 , a second pulley  72 , a second track  80 , and a second shuttle  82 , and a second spring  76 . A first end  77  of the second cable  75  attaches to the leading end  163  of the striker  160 . The second cable  75  engages the second pulley  73  to change the direction of the second cable  75 . A second end  79  of the first cable  55  attaches to the shuttle  82 . The extension end  74  of the second gas spring  70  fixedly engages the shuttle  82 . The second cable  75  connects the extension end  74  of the second gas spring  70  and the shuttle  82 . The extension of the extension end  74  moves the shuttle  82 , which pulls on the second cable  75  to close the second door  30 . 
     A plug  83  is positioned in the internal diameter of the spring  76 . The plug  83  and the spring  76  are generally positioned in the interior of the second spring housing  71 . A nut  85  connects the base end  72  of the second gas spring  70  to the plug  83 . The base end  72  has a larger external diameter  87  than the plug  83 . The external diameter  87  presses against the spring  76  in order to compress the spring  76 . The plug  83  helps to maintain the shape of the spring  76  and prevent the spring  76  from tangling. The plug  83  also provides a limit to the compression of the spring  56 . 
     As shown in  FIG. 1 , components of the first spring assembly  150  and the second spring assembly  170  may be mounted to the upper surface of the cabinet  10 . In operation of the cabinet  10  with the door sequencer  40 , the door sequencer  40  prevents the second door  30  from closing before the first door  20 . The door sequencer  40  prevents the second door  30  from closing on top of the first door  20 . The toggle  140  holds the second door  30  from closing until the shuttle  60  strikes the toggle  140  causing the toggle  140  to pivot and move the catch  170  out of the way of the locking surface  165  of the striker  160 . Once the catch  170  is moved out of the way of the locking surface  165  of the striker  160 , the second door  30  can close. 
     In the aspect of  FIGS. 1-8 , the second door  30  (in this particular arrangement), must always open first as the door handle is located on the second door  30  and the second door  30  also covers the flange  25  of the first door  20 . The second door  30  can be opened at any time without first opening the first door  20 . Once the second door  30  is opened, then the first door  20  may be opened. The door sequencer  40  is engaged after the both doors  20  and  30  have been opened beyond approximately 15° or so from their closed positions. The second door  30  needs to be opened first to allow the first door  20  to open since the second door  30  covers the flange  25  of the first door  20  to seal the cabinet  10 . Once the second door  30  has been opened far enough, the first door  20  may then be opened, which will engage the door sequencer  40  to prevent the second door  30  closing prior to the first door  20 . Due to the door sequencer  40 , the second door  30  will not close until the first door  20  is closed. 
     It should be understood from the foregoing that, while particular embodiments of the invention have been illustrated and described, various modifications can be made thereto without departing from the spirit and scope of the present invention. Therefore, it is not intended that the invention be limited by the specification; instead, the scope of the present invention is intended to be limited only by the appended claims.

Summary:
A cabinet with a door sequencer is described. The cabinet includes a first door and a second door to close an opening of the cabinet. A first gas spring closes the first door before a second gas spring closes the second door. The door sequencer automatically closes the first and second doors in a correct order to promote compliance with safety regulations.