Patent Publication Number: US-6705377-B1

Title: Horizontal folding door system

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to horizontal folding doors and more specifically to an improved horizontal folding door system, which provides increased rigidity when open. 
     2. Discussion of the Prior Art 
     The prior art includes at least two types of horizontal folding door systems. One type of horizontal folding door system includes two horizontal folding doors. Each horizontal folding door includes a plurality of folding door sections. The sections are approximately two feet in length. The plurality of folding door sections stack-up together, when closed. The drawback to this type of horizontal folding door system is that the plurality of folded door sections decrease the opening size. Another type horizontal folding door system includes two folding doors. Each folding door includes two folding door sections. The drawback to this type of horizontal folding door system is that the folding door sections are so large that they are subject to twisting. A sliding pivot point is formed on an end of a second door section, which makes the folding door unstable in an open position, during a wind gust. 
     Accordingly, there is a clearly felt need in the art for an improved horizontal folding door system, which provides increased rigidity when open, a maximum size door opening, and an improved locking system. 
     SUMMARY OF THE INVENTION 
     The present invention provides improved folding doors, which are more rigid when open than that of the prior art. An improved horizontal folding door system includes a first folding door, a second folding door, a trolley track, and at least two trolleys. The improved horizontal folding door system covers a large door frame opening for an airplane hanger or other building structure. The door frame includes a horizontal frame member terminated by a single vertical frame member on each end thereof. Each folding door includes a first door section and a second door section. One side of each first door section is pivotally attached to one vertical frame member and the other side of each first door section is pivotally attached to one side of a single second door section. The first door section preferably has a shorter length than the second door section. However, a door frame opening may also be covered with a single folding door instead of two. 
     The trolley track is attached to the horizontal frame member. At least one trolley is attached to a top of each second door section. Preferably, at least one locking pin extends from a top of each second door section and at least one locking pin extends from a bottom of each second door section. All the locking pins disposed on each second door section are preferably controlled by a single actuation device. A plurality of locking cavities must be formed in a floor of a building structure and a plurality of locking cavities are preferably formed in at least one overhead stud. A single locking cavity receives each locking pin. 
     Each door section preferably includes a bottom rail, two vertical rails and at least two horizontal girts. The bottom rail is terminated by a single vertical rail on each end thereof. Each vertical rail is structured to receive an end of the at least two horizontal girts. Each vertical rail is preferably structured to receive an end of a face plate. Reinforcing girts may be used to prevent the door sections from twisting. The reinforcing girts are retained in the two vertical rails. A second embodiment of each door section includes a front sheet, a rear sheet, a foam inner layer, and two end vertical rails. The front and rear sheets are retained, such that a space is created therebetween. Foam is blown into the space between the front and rear sheets to form a foam door section. A single vertical end rail is attached to each end of the foam door section. 
     Accordingly, it is an object of the present invention to provide an improved horizontal folding door system, which has increased rigidity when open. 
     It is a further object of the present invention to provide an improved horizontal folding door system, which has a maximum size door opening. 
     Finally, it is another object of the present invention to provide an improved horizontal folding door system, which has an improved locking system. 
     These and additional objects, advantages, features and benefits of the present invention will become apparent from the following specification. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front view of an airplane hanger with a door frame opening. 
     FIG. 2 is a front view of an improved horizontal folding door system in accordance with the present invention. 
     FIG. 3 is an end view of an improved horizontal folding door system in accordance with the present invention. 
     FIG. 4 is a top view of an improved horizontal folding door system in accordance with the present invention. 
     FIG. 5 is a rear view of a second folding door section of an improved horizontal folding door system with at least two locking pins in accordance with the present invention. 
     FIG. 5 a  is an end view of first and second pulleys used for retaining locking pin cables in an improved horizontal folding door system in accordance with the present invention. 
     FIG. 6 is a top view of a first folding door of an improved folding horizontal door system in accordance with the present invention. 
     FIG. 7 is a front view of a structural folding door section without a front panel of an improved folding door system in accordance with the present invention. 
     FIG. 8 is a top view of a structural folding door section without a front panel retained therein of an improved horizontal folding door system in accordance with the present invention. 
     FIG. 9 is a top cross sectional view of a foam folding door section of an improved horizontal folding door system in accordance with the present invention. 
     FIG. 10 is a front view of a foam folding door section of an improved horizontal folding door system in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference now to the drawings, and particularly to FIG. 2, there is shown a front view of an improved horizontal folding door system  1 . With reference to FIGS. 3 and 4, the improved horizontal folding door system  1  includes a first folding door  10 , a second folding door  12 , a trolley track  14 , and at least two trolleys  16 . With reference to FIG. 1, the improved horizontal folding door system  1  covers a door frame opening  102  of an airplane hanger  100  or other building structure. The door frame opening  102  includes a horizontal frame member  104  terminated by a single vertical frame member  106  on each end thereof. 
     Each folding door  10 ,  12  includes a first door section  18  and a second door section  20 . One side of the first door  18  section is pivotally attached to one vertical frame member  106  with at least one hinge  22  (a single continuous hinge may be used). The other side of the first door  18  is pivotally attached to one side of the second door section  20  with at least one hinge  24 . Preferably, the first door section  18  has a shorter length than the second door section  20 . The shorter length of the first door section  18  relative to the second door section  20  enables a portion of the second door section  20  to be inside the structure, when open. However, a door frame opening may also be covered with a single folding door  10 ,  12  instead of two. 
     The trolley track  14  is attached to the horizontal frame member  104 . At least one trolley  16  is attached to a top of each second door section  20  substantially at the other side thereof. With reference to FIG. 6, a trolley threaded hole  21  is, formed in a top of each second door section  20  to threadably receive a single trolley  16 . The trolley threaded hole  21  is preferably spaced a distance “A” from an inside edge of the second door section  20 . The distance “A” is less than thickness of the second door section  20 . The trolley threaded hole  21  is also positioned along a length of the second door section  20 ; such that a portion of the second door section  20  is disposed inside the building structure, when the second door section  20  is fully open. 
     With reference to FIGS. 5 &amp; 6, at least one top locking pin  26  extends from a top of each second door section  20  and at least one bottom locking pin  28  extends from a bottom of each second door section  20 . The at least one top locking pin  26  is spring loaded, such that thereof is normally in an extended position. The at least one bottom locking pin  28  is preferably gravity actuated, but may be spring loaded. Locking pins are well known in the art and need not be explained in detail. All the locking pins disposed on each second door section  20  are preferably controlled by a single actuation device  29 . The single actuation device  29  includes a rotation arm  40 . The single actuation device is rotated with a handle or key (not shown) to pivot the rotation arm  40  and retract the locking pins  26 ,  28 . With reference to FIG. 5, the single actuation device  29  is preferably located horizontally inward from the one side of the second door section  20 , a dimension “C.” A center of a single trolley  16  is preferably located horizontally inward from other side of the second door section  20 , a dimension “B.” Dimension “B” is preferably substantially equal to dimension “C.” Locating the trolley  16  and the actuation device  29  as shown in FIG. 5, reduces the effort required to open the first and second folding doors. A portion of each second door section  20  is disposed inside the airplane hanger  100  or building structure when the first and second folding doors are fully open. 
     With reference to FIG. 5 a , one of the top locking pins  26  is retracted by a first top cable  30  around a first pulley  32 . One of the bottom locking pins  28  is retracted by a first bottom cable  36  around a second pulley  34 . The first top and bottom cables are attached to one end of a lengthwise cable  38 . The other end of the lengthwise cable  38  is attached to a rotation arm  40  around a second pulley  35 . Another top locking pin  26  is retracted by second top cable  42 , when the rotation arm  40  is pivoted. Another bottom locking pin  28  is retracted by a second bottom cable  44 , when the rotation arm  40  is pivoted. The second bottom cable  44  is supported by the first pulley  33 . 
     At least four bottom locking cavities (not shown) are formed in a floor of the airplane hanger  100  or other building structure. One set of bottom locking cavities would lock the first and second folding doors in a closed position and another set of bottom locking cavities would lock the first and second folding doors in an open position. At least two top locking cavities (not shown) are preferably formed in an overhead stud  108  for locking the first and second folding doors in a closed position. Another overhead stud (not shown) would be required to lock the first and second folding doors in an open position on a top thereof. A single locking cavity receives each locking pin. One set of top locking cavities lock the first and second doors in an open position and another set of top locking cavities lock the first and second doors in an open position. 
     With reference to FIGS. 7 &amp; 8, each door section  18 ,  20  includes a bottom rail  46 , two vertical rails  48  and at least two horizontal girts  50 . The bottom rail  46  is terminated by a single vertical rail  48  on each end thereof. Each vertical rail  48  is structured to receive an end of the at least two horizontal girts  50 . Each vertical rail  48  may include a retainer slot  52  which is sized to receive an end of a face plate  54 . At least one reinforcing girt  56  may be used to strengthen each door section  18 ,  20  to prevent twisting. The at least one reinforcing girt  56  is retained in the two vertical rails  48 , between two horizontal girts  50 . Structural doors are well known in the art and need not be explained in detail. 
     With reference to FIGS. 9 and 10, a second embodiment of each door section  18 ′,  20 ′ includes two vertical end rails  58  and at least one insert door section  60 . Each insert door section  60  includes a front sheet  62 , a rear sheet  64  and a foam inner layer  66 . The front and rear sheets are retained, such that a space is created therebetween. The foam inner layer  62  is blown into the space between the front and rear sheets to form a single insert door section  60 . A single vertical end rail  58  is attached to each end of the at least one insert door section  60 . 
     While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.