The invention described herein relates to a utility vault door, or access door, positionable between closed, partially opened, and fully opened orientations and including at least one compression spring lift-assist mechanism for countering the weight of the vault door when positioning between the various orientations. The door may be selectively locked in the partially opened orientation and opened sufficiently for the convenient ingress and egress of large equipment therethrough.

RELATED APPLICATION DATA 
     This application claims priority to co-pending Provisional Application Ser. No. 61/934,261 filed on Jan. 31, 2014 and entitled “Access Door with Lift Assist.” The content of this application is fully incorporated by reference herein for all purposes. 
    
    
     TECHNICAL FIELD 
     This disclosure relates to a vault door. More particularly the invention relates to a vault door that is selectively positionable between closed, partially opened, and fully opened orientations and includes a series of lift-assist mechanisms for ease of opening and closing from any orientation. 
     BACKGROUND OF THE INVENTION 
     The use of access doors is known in the prior art. These doors are often mounted within the ground and control access to underground utilities. However, existing doors often have several disadvantageous limitations. For example, because access doors have to be strong enough to prevent unauthorized access as well as to withstand vehicle traffic, they are traditionally heavy and cumbersome. Further, the weight of an access door often makes it difficult to permit opening by a single user. 
     Access doors must also be capable of opening wide enough to accommodate ingress and egress of large equipment. However, most doors are not adapted to be held open on their own or designed to achieve a fully-opened orientation. 
     Thus, a need exists in the art for a vault door that is sufficiently strong and that provides a large enough opening for equipment but that is easy to open without undue strain or force. The vault door of the present disclosure is aimed at overcoming this and other needs in the art. 
     SUMMARY OF THE INVENTION 
     The invention described herein relates to a utility vault door, or access door, positionable between closed, partially opened, and fully opened orientations and including at least one compression spring lift-assist mechanism for countering the weight of the vault door when positioning between the various orientations. 
     The invention disclosed herein has several important advantages. For example, this disclosure provides an access door with two discrete opened orientations. 
     Another advantage of the present disclosure includes providing an access door that can be locked in a partially opened orientation. 
     Yet another advantage of the present disclosure includes providing an access door with at least one compression spring lift-assist mechanism for overcoming the weight of the door and thereby easing the positioning of the door between a plurality of orientations. 
     Still yet another advantage of the present disclosure includes providing primary and secondary compression spring lift-assist mechanisms for overcoming the weight of the door and thereby easing the positioning of the door between a plurality of orientations. 
     Another advantage of the present disclosure includes providing a means to obstruct a floor opening with a frame and cover assembly that allows for the complete 180 degree rotation of the door from the open to closed positions, with the operation complimented in both directions with compression lift assist devices. 
     Yet another advantage of the present disclosure includes providing at least one lift-assist in which no more than 30 pounds of lift is required at any point in the 180 degree arc of the opening door, thereby allowing for safer and more ergonomic operation of the door. 
     Another advantage is realized by providing a first set of lift-assist mechanisms for assisting with the movement of the door between the 0 to 90 degree positions, and by providing a second set of lift-assist mechanisms for assisting the movement of the door between the 90 to 180 degree positions. 
     Still yet another advantage of the present invention includes providing a door with lift assistance when positioning between the 180 degree and 90 degree orientations. 
     The foregoing has outlined rather broadly the more pertinent and important features of the present invention in order that the detailed description of the invention that follows may be better understood so that the present contribution to the art can be more fully appreciated. Additional features of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present disclosure and its advantages, reference is now made to the following descriptions, taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a perspective view of the vault door in the closed orientation. 
         FIG. 2  is a perspective view of the vault door showing the peripheral edge. 
         FIG. 3  is a side elevational view of the vault door being opened. 
         FIG. 4  is a perspective view of the vault door being opened. 
         FIG. 5  is a perspective view of the vault door at the 90 degree orientation. 
         FIG. 6  is a side elevational view of the vault door at the 90 degree orientation. 
         FIG. 7  is a perspective view of the vault door at the 90 degree orientation. 
         FIG. 8  is a detailed view of the locking mechanism with the hinge plate locked. 
         FIG. 9  is a detailed view of the locking mechanism with the hinge plate unlocked. 
         FIG. 10  is a perspective view of the vault door at the 180 degree orientation. 
         FIG. 11  is a perspective view of the vault door being closed. 
         FIG. 12  is a perspective view of the vault door in the partially opened orientation. 
         FIG. 13  is a detailed perspective view of the lift assist mechanisms of the present invention. 
     
    
    
     Similar reference numerals refer to similar parts throughout the several views of the drawings. 
     
       
         
               
             
               
               
             
           
               
                   
               
               
                 PARTS LIST 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                  10  
                 ground mounted vault closure 
               
               
                  12  
                 rectangular frame 
               
               
                  14  
                 anchor members 
               
               
                  16  
                 latch receiver 
               
               
                  18  
                 locking pin receiver 
               
               
                  20  
                 ground 
               
               
                  22  
                 vault door 
               
               
                  24  
                 plurality of reinforcing ribs 
               
               
                  26  
                 primary apertured compression plate 
               
               
                  28  
                 secondary apertured compression 
               
               
                   
                 plate 
               
               
                  34  
                 interior handle 
               
               
                  36  
                 slide formed within peripheral edge 
               
               
                  38  
                 first locking detent 
               
               
                  39  
                 second locking detent 
               
               
                  40  
                 stowable exterior lifting handles 
               
               
                  42  
                 male latch 
               
               
                  44  
                 hold-open arm 
               
               
                  46  
                 first end of hold-open arm 
               
               
                  48  
                 second end of hold-open arm 
               
               
                  50  
                 primary lift assist mechanisms 
               
               
                  52 
                 pivotal hinge 
               
               
                  54 
                 first end of pivotal hinge 
               
               
                  56 
                 second end of pivotal hinge 
               
               
                  58 
                 first compression spring 
               
               
                  60 
                 second compression spring 
               
               
                  62 
                 first end of first compression spring 
               
               
                  63 
                 first end of second compression spring 
               
               
                  64 
                 second end of first compression spring 
               
               
                  65 
                 second end of second compression 
               
               
                   
                 spring 
               
               
                  66 
                 first support rod 
               
               
                  68 
                 first end of first support rod 
               
               
                  70 
                 second end of first support rod 
               
               
                  72 
                 primary compression washer 
               
               
                  74 
                 secondary lift assist mechanism 
               
               
                  76 
                 connector hinge 
               
               
                  78 
                 first end of the connector hinge 
               
               
                  80 
                 second end of the connector hinge 
               
               
                  82 
                 third spring 
               
               
                  81 
                 second support rod 
               
               
                  86 
                 first end of third spring 
               
               
                  88 
                 second end of third spring 
               
               
                  90 
                 first end of second support rod 
               
               
                  92 
                 second end of second support rod 
               
               
                  94 
                 secondary compression washer 
               
               
                  95 
                 end cap 
               
               
                  96 
                 hinge plate 
               
               
                  98 
                 first end of hinge plate 
               
               
                 100 
                 second end of hinge plate 
               
               
                 102 
                 aperture in hinge plate 
               
               
                 104 
                 locking pin 
               
               
                   
               
             
          
         
       
     
     DETAILED DESCRIPTION OF EMBODIMENTS 
     The present invention relates to a vault door. More particularly the invention relates to a vault door that is selectively positionable between closed, partially opened, and fully opened orientations and includes a series of compression spring lift-assist mechanisms for ease of opening and closing. The various components of the present invention, and the manner in which they interrelate, are described in greater detail hereinafter. 
     Initially with reference to  FIGS. 1 and 2 , the invention provided herein includes a ground mounted vault closure  10  selectively positionable between closed, partially opened, and fully opened orientations. In one embodiment of the invention, the partially opened orientation is opened about 90 degrees relative to the closed orientation and the fully opened orientation is opened about 180 degrees relative to the closed orientation. However, other angular orientations for the partially opened and fully opened orientations are also possible. 
     The closure includes a rectangular frame  12  having inner and outer peripheral extents and a series of anchor members  14  positioned upon the outer peripheral extent. Also included are a latch receiver  16  (see  FIG. 12 ) and a locking pin receiver  18  (see  FIG. 9 ) formed within the frame  12 . In the embodiment of the invention depicted in  FIG. 1 , the frame  12  is mounted into the ground  20  and defines an access opening for an underground vault. However, embodiments in which the frame  12  is set to any other predetermined mounting location are considered to be within the scope of the present invention. 
     With reference now to  FIGS. 2-4 , one embodiment of the invention includes a vault door  22  having interior and exterior surfaces and peripheral edges, the interior surface including a plurality of reinforcing ribs  24 , a pair of primary apertured compression plates  26  and a pair of secondary apertured compression plates  28 . One embodiment of the present invention includes an interior handle  34  for assisting with the movement of the vault door  22  when desirable. Further, a slide  36  with opposing first  38  and second  39  locking detents may be formed within one of the peripheral edges of the vault door  22 . As will be described in greater detail hereinafter, the slide  36  enables a user to securely position the vault door  22  in the partially opened orientation as desired. 
     In one exemplary embodiment of the present invention, the vault door  22  further includes a pair of stowable exterior lifting handles  40  (see  FIG. 2 ) and a male latch  42  (see  FIG. 4 ). The vault door  22  is pivotally connected to the rectangular frame  12 . In a closed orientation, the vault door  22  overlies the rectangular frame  12  and the male latch  42  associated with the vault door  22  is received by the latch receiver  16  to lock the vault door  22  and deter access to the underground vault. 
     Referring now initially to  FIGS. 3 and 4 , one embodiment of the invention includes a one piece hold-open arm  44  having first  46  and second  48  ends and an intermediate extent therebetween, the second end  48  of the arm being slidably received within the slide  36  and being selectively positionable between the first  38  and second  39  locking detents. 
     With continued reference to  FIG. 4  and with reference to  FIG. 13 , an embodiment of the invention disclosed herein includes a pair of primary compression spring lift-assist mechanisms  50 , each primary mechanism including a pivotal hinge  52  having first  54  and second  56  ends and first and second orientations. When the door  22  is in either the closed or partially opened orientation, the pivotal hinge  52  is in the first orientation, the first orientation of the pivotal hinge  52  being substantially parallel to the peripheral extent of the frame  12 . When the door  22  is in the fully opened orientation, the pivotal hinge  52  is in the second orientation, the second orientation of the pivotal hinge  52  being rotated about 90 degrees relative to the first orientation and substantially perpendicular to the peripheral extent of the frame  12 . The first end  54  of each pivotal hinge  52  is fixedly connected to the vault door  22 . 
     In one embodiment of the invention described herein, each primary mechanism  50  further includes first  58  and second  60  compression springs. Each first compression spring  58  includes a first end  62  and a second end  64 . Likewise, each second compression spring  60  includes a first end  63  and a second end  65 . Each spring has both compressed and decompressed orientations, and the second spring  60  positioned substantially within the first spring  58 . The use of two springs in the primary mechanism permits a fine adjustment of the force provided to assist the opening of the vault door, as well as to prevent slamming. 
     Extending axially through each first  58  and second  60  compression spring is a first support rod  66  having opposing first  68  and second  70  ends. The first end  60  of each support rod  66  further includes a primary compression washer  72 . Further, the first end  68  of each first support rod  66  is pivotally connected to the second end  56  of the pivotal hinge  52  and the second end  70  of each first support rod  66  is slidably positioned within an aperture of a corresponding primary apertured compression plate  26 . By being slidably positioned within an aperture of a corresponding primary apertured compression plate  26 , each first support rod  66  is not only held in a desirable position relative to the other components of the invention, but also permitted to slide forward or backward through the apertured compression plates upon a changing of the orientation of the vault door  22 . 
     The first ends  62  of each first  58  and second  60  spring are positioned against the primary compression washer  72  of the corresponding first support rods  66  and the second ends of each first  58  and second  60  spring are positioned against the corresponding primary apertured compression plate  26  receiving the first support rod  66 . This particular positioning of the first and second springs provides a pair of corresponding surfaces for each spring to be either compressed or decompressed against when changing the orientation of the vault door  22 , and provides lifting assistance between the closed and partially opened orientations. 
     One embodiment of the present invention ( FIG. 13 ) also includes a pair of secondary compression spring lift-assist mechanisms  74  for providing lift assistance between the partially opened and fully opened orientations, each secondary mechanism  74  including a connector hinge  76 , each connector hinge  76  having first  78  and second  80  ends and first and second orientations. In the first orientation, the connector hinge  76  is substantially parallel to the peripheral extents of the frame  12 . In the second orientation, the connector hinge  76  is rotated approximately 90 degrees and thus substantially perpendicular to the peripheral extents of the frame  12 . The first end  78  of each connector hinge  76  is pivotally connected to the frame  12 . 
     Also included as part of each secondary lift assist mechanism  74  is a third spring  82  and a second support rod  84  positioned axially therethrough. Each third spring  82  has a first  86  and a second end  88  and compressed and decompressed orientations, and each second support rod  84  has opposing first  90  and second  92  ends. The first end  90  of each second rod  84  is pivotally connected to the second end  80  of the connector hinge  76 . A secondary compression washer  94  is connected to the second end  92  of each second rod  84 . In one embodiment of the invention, each secondary compression washer  94  is connected to the second end  92  of a corresponding second rod  84  by an end cap  95 . The end cap  95  may be threadably secured to a second end  92 , and may comprise a nut. Accordingly, by turning the end cap either clockwise or counter-clockwise, the distance between the secondary compression washer  94  and the secondary apertured compression plate  28  may be increased or decreased as desired. This increase or decrease in the distance between the secondary compression washer  94  and the secondary apertured compression plate  28  subsequently either increases or decreases the compression of the third spring  82 , thereby permitting an adjustment of the lift-assist force applied by the third spring  82 . Further, each second rod  84  is slidably positioned in an aperture of a corresponding secondary apertured compression plate  28 , thereby maintaining each third spring  82  and each second support rod  84  and a desirable orientation relative to the other components of the present invention and providing a surface upon which the third spring  82  may be compressed or decompressed, depending of the orientation of the vault door  12 . Thus, the first end  86  of each third spring  82  is positioned against the corresponding secondary apertured compression plate  28  and the second end  88  of each third spring  82  is positioned against a secondary compression washer  94 , thereby providing two surfaces between which the third spring  82  is either compressed or decompressed, depending on the orientation of the vault door  12 . 
     With the door  22  in the closed orientation, the connector hinge  76  and the second support rod  84  are substantially in linear alignment. As the door is opened from the closed orientation to the partially opened orientation, the connector hinge  76  and the second support rod  84  remain in linear alignment as their respective angles increase from about 0 to about 90 degrees relative to the frame  12 . As the door  22  is further opened from the partially opened orientation to the fully opened orientation, the connector hinge  76  remains substantially stationary at about 90 degrees relative to the frame  12  and the angle of the second rod  84  increases from about 90 to about 180 degrees relative to the frame  12 . Accordingly, when the door  22  is positioned in the fully opened orientation, the connector hinge  76  and the second support rod  84  are substantially perpendicular. Because the connector hinge  76  remains stationary as the door  22  door travels between the partially opened and fully opened orientations, the distance between the corresponding secondary apertured compression plate  28  and the first end  90  of the second support rod  84  increases, which subsequently compresses the corresponding third spring  82  (see  FIG. 10 ). This compression of the third spring  82  counters the force of gravity against the door, thereby easing the opening of the door  22  to the fully opened orientation and preventing slamming. Conversely, decompression of the third spring  82  when positioning between the about 180 degree, or fully opened, and about 90 degree, or partially opened, orientations also counters the force of gravity on the vault door, thereby assisting a user in lifting the door from the fully opened orientation to the partially opened orientation. 
     As will be appreciated by one of ordinary skill in the art, doors of different weights may require different combinations of first, second, and third springs in order to provide the force necessary to achieve the desired lift-assist ratio. For example, heavier doors may require a combination of springs that provide a greater force relative to that required to accommodate a lighter door. Further, the selection of the desired springs may be dictated by the size of the door provided. 
     The springs utilized may be selected from any number of commercially available springs. For example, the first spring  58  may be selected from a group including but not limited to regular springs, which are smaller and operate on a lower range of forces. There are at least five regular types of springs, which are designated small, medium, large, x-large, and xx-large. The second spring  60  may be selected from a group including but not limited to springs with ¼, 5/16, and 11/32 coil diameters that are more rigid (i.e. stronger or capable of resisting or providing a greater force) than the regular springs. For example, an embodiment using 3 small springs, 2 medium springs and 1 large spring, where the collective strength of the springs lifts the cover by providing specific value, or force, of lift assist, may be provided. 
     It will also be appreciated by one of ordinary skill in the art that lift-assist mechanisms using other known force generating or resisting devices may be readily substituted for the spring-based mechanisms described herein. For example, a lift-assist mechanism utilizing hydraulic cylinders, pneumatic cylinders, tension springs, and the like may be readily interchangeable and thus are considered to be within the scope of the present invention. 
     With reference now to  FIGS. 8 and 9 , one embodiment of the invention provided herein may further include a hinge plate  96  having a first end  98  rotatably secured to the frame  12  and a second end  100  rotatably secured to the first end  46  of the hold-open arm  44 . The hinge plate includes an aperture  102  for receiving a locking pin  104 , enabling the locking of the hinge plate  96  in a first orientation substantially parallel to the peripheral extent of the frame  12 . The hinge plate pivots between the first orientation parallel to the frame and a second orientation rotated about 90 degrees relative to the frame. The inclusion of the hinge plate as herein described permits the selective positioning of the vault door  22  in the partially opened orientation. Removal of the locking pin  104  permits the vault door  22  to achieve the fully opened orientation. 
     In use, the vault door  22  is in the closed orientation with the hinge plate  96  in the first orientation, each pivotal hinge  52  in the first orientation, each connector hinge  76  in the first orientation, each first  58  and second  60  spring in the compressed orientation, each third spring  82  in the decompressed orientation, the second end  48  of the hold-open arm  44  adjacent to the first detent  38 , and the locking pin  104  positioned through the aperture  102  and into the locking pin receiver  18  in the inner peripheral extent of the rectangular frame  12 . 
     The vault door  22  is in the partially opened orientation with the hinge plate  96  in the first orientation, each pivotal hinge  52  in the first orientation, each connector hinge  76  in the second orientation, each first  58  and second  60  spring in the decompressed orientation, each third spring  82  in the decompressed orientation, the second end  48  of the hold-open arm  44  in the second detent  39 , and the locking pin  104  positioned through the aperture  102  and into the locking pin receiver  18  in the inner peripheral extent of the rectangular frame  12 . 
     Removal of the locking pin  104  permits the vault door  22  to achieve the fully opened orientation with the hinge plate  96  in the second orientation, each pivotal hinge  52  in the second orientation, each connector hinge  76  in the second position, each first  58  and second  60  spring in the decompressed orientation, each third spring  82  in the compressed orientation, and the second end  48  of the hold-open arm  44  in the second detent  39 . 
     Although this disclosure has been described in terms of certain embodiments and generally associated methods, alterations and permutations of these embodiments and methods will be apparent to those skilled in the art. Accordingly, the above description of example embodiments does not constrain this disclosure. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of this disclosure.