Patent Publication Number: US-2005139331-A1

Title: Overhead door apparatus with enclosed counterbalance mechanism

Description:
FIELD OF THE INVENTION  
      The subject invention relates generally to vertically lifted doors, and more specifically to an integral unit comprised of a vertically liftable door having a hollow door section which houses the counterbalance mechanism responsible for counteracting the effect of gravity on the door as it moves from the closed to open position. The device is particularly useful for residences, aircraft hangers, automotive shops, barns, aircraft and blimp hangers, automotive shops, commercial warehouses, military field houses and similar structures.  
     BACKGROUND OF THE INVENTION  
      Liftable overhead doors are not new and are seen frequently in buildings such as homes, aircraft hangers, automotive shops, barns, aircraft and blimp hangers, automotive shops, commercial warehouses, military field houses and similar structures. A wide variety of vertically movable doors are currently used in industrial and other settings. For example, one type of vertically movable door is comprised of a conventional sectional door having of a series of hingedly attached panels with stemmed rollers disposed on opposed lateral edges. Such sectional doors are typically movable between a closed or blocking position and an open or storing position relative to a doorway. For this purpose, a curved guide track is provided on either side of the doorway for receiving the rollers of the panels. The track is comprised of a substantially vertical portion disposed adjacent to the doorway opening, a substantially horizontal portion disposed above and behind the doorway, and an intermediate curved portion interconnecting them on either side of the doorway providing a continuous guide track for receiving the stemmed rollers of the panel sections. In this construction, the door is substantially horizontal when in the open storing position. Another type of vertically movable door is a vertically storable door which moves in a continuous plane between the blocking and storing positions along substantially straight and vertical guide tracks disposed above the doorway opening. In these ways, the mechanical advantage of the lifting force needed to counterbalance the door is recognized to vary and different combinations of lifting devices are used to provide a statically balanced overhead door.  
      With most vertically movable doors, a counterbalancing device is externally mounted along the guide tracks above the door is provided for counteracting the effect of gravity on the door as it moves between the blocking and storing positions. Such counterbalancing devices typically include a cable system which is attached to the door and a spring which is operatively connected to the cable system. When the door moves from the storing position, the energy stored in the spring becomes stressed and provides a force which counteracts the weight of the door. In this way, the spring controls the descent of the door as it moves towards the doorway-blocking position. Conversely, when the door is raised from the doorway-blocking position, the spring provides a lifting force which makes the door easier to raise. Unfortunately, such mechanisms lack aesthetic appeal and frequently play host to dirt, spider webs and insects which cling to its greased components. It would therefore, be desirable to conceal such mechanisms within the door itself thereby providing a more aesthetically pleasing door assembly having internal components which are substantially free of foreign debris.  
      U.S. Pat. No. 6,505,381 issued to Thomson on Jan. 14, 2003, teaches pulleys and a cable placed within the body of a folding plane. The &#39;381 invention provides a hinge system for deploying panels or other structures from a satellite or spacecraft. While the &#39;381 patent fits the hinge system within a telescope housing in the deployed position it does not place the entire mechanism within a single element of the deployment panel.  
      U.S. Pat. No. 5,560,658 issued to Coolman on Oct. 1, 1996, teaches an overhead bi-fold door With the cable and pulley system within the frame of the door. However, it is not enclosed on both sides.  
      U.S. Pat. No. 6,042,158 issued to Horn on Mar. 28, 2000, teaches a cable actuated locking system inside the body of an overhead door. It does not, however, teach a hollow door panel encasing a counterbalance mechanism.  
      U.S. Pat. No. 3,774,341 issued to Schoonover on Nov. 27, 1973 and U.S. Pat. No. 4,28,016 issued to Dickson on Mar. 20, 2000, teach cable and spring operating systems for overhead doors that are encased in the frame around the door.  
      U.S. Pat. No. 1,530,762 to Dautrick issued Mar. 12, 1925, teaches a dual race cable drum having an inner race that spools a cable connected to a tensioning member and a larger outer race with separate cables connected to the door bottom. It does not teach a dual race cable drum to turn about its longitudinal axis perpendicular to its tensioning member axis.  
      None of the above described inventions teach a vertically liftable door having a counterbalance mechanism enclosed within a panel of the door.  
     SUMMARY OF THE INVENTION  
      In general, the present invention contemplates a vertically acting overhead door system, comprising: a door comprised of at least one hollow door section; said door being moveable between a closed vertical position and an open horizontal position relative to a doorway; and a counterbalance mechanism housed within said at least one hollow door section to facilitate the movement of the door between open and closed positions. The counterbalance mechanism within the hollow door section replaces conventional counterbalance mechanisms associated with vertically raisable doors which are mounted outside of the door either above the door frame or parallel to neighboring guide rails.  
      More specifically, all embodiments of the subject invention will be comprised generally of a vertically movable door; the door being comprised of at least one hollow door section containing a counterbalance mechanism therein for counteracting the effect of gravity on the door and for controlling the movement of the door between the open and closed positions.  
      For instance, a first embodiment of the subject invention provides a vertically moveable door comprising at least one hollow door section containing a counterbalance mechanism therein, the counterbalance mechanism being comprised of a tensioning member, cable drums fixed to each end of the tensioning member, a cable spooled around each cable drum, and a plurality of direction transfer pulleys, wherein said cable passes through said direction transfer pulleys and out of the hollow door section to a fixed point adjacent to the door.  
      In another embodiment of the invention, a vertically moveable door is suspended in a fixed track, said door comprising at least one hollow door section containing a counterbalance mechanism therein, the counterbalance mechanism being comprised of a tensioning member, a plurality of pulleys at least one of which is fixed to the end of the tensioning member, a plurality of cables attached to fixed points within the hollow door panel and running through the pulleys and exiting the sides of the hollow door section to a fixed point adjacent the door.  
      Accordingly, it is a primary object of the subject invention to provide an integral overhead door unit wherein the counterbalance mechanism is enclosed within the door itself.  
      Another object of the subject invention is to provide a complete functional counterbalance assembly within the construction of the door itself while using existing track configurations for mounting the door.  
      It is also an object of the present invention to take advantage of the construction of conventional steel roll formed door sections with a thickness ranging from 2 inches to 6 inches by modifying them to accept this unique counterbalance mechanism without substantial retooling of manufacturing equipment. Further, the invention may be utilized with door sections of greater or lesser thickness through the use of reinforcing members and hardware.  
      It is another object of the present invention to provide a counterbalance mechanism for vertically moveable doors using a single spring in the body of a door section wherein the spring is free moving and suspended between the door cables and the door itself.  
      Still another object of the present invention is to provide a counterbalance mechanism for vertically moveable doors using one extension spring or a combination of springs in the body of a door section where the cables pass around a common pulley extending the springs and then to each bottom pulley to a fixed point adjacent the door.  
      Another object of the present invention is to provide a counterbalance mechanism for vertically moveable doors, said system using a torsion spring assembly inside the body of the door, or a section thereof, said spring assembly effecting the functional counterbalancing of the vertically moveable door.  
      Yet another object of the present invention is to provide a counterbalance mechanism for vertically moveable doors, said system using torsion springs whereby tension may be applied to the springs by a convenient gear reduction device within the hollow door section and with or without the addition of a drive motor.  
      These together with other objects of the invention, along with the various features of novelty which characterize the invention, are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its advantages and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated preferred embodiments of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  shows a perspective view of the vertically moveable overhead door assembly of the present invention in its closed position, portions of which are depicted in cutaway view to reveal the counterbalance mechanism contained thereof.  
       FIG. 2  shows a rear view of the vertically moveable overhead door assembly of the present invention with the rear panel removed to reveal a preferred embodiment of the counterbalance mechanism thereof, in this case comprised of an extension spring design.  
       FIG. 3  shows an alternate embodiment of the counterbalance mechanism of the subject vertically moveable overhead door assembly of the present invention.  
       FIG. 4  shows a perspective view of the vertically moveable overhead door assembly in its closed position and further showing an alternative fixed spring counterbalance assembly.  
       FIG. 5  shows a perspective view of yet another embodiment of the vertically moveable overhead door assembly of the subject invention having a freely suspended, spring counterbalance assembly.  
       FIG. 6  shows a detailed view of the bottom pulley fixture and pivotal idler cam. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Referring first to  FIG. 1 , a first embodiment of the subject overhead door assembly is depicted and designated generally by reference numeral  10 . The overhead door assemblies  10  of the subject invention are used in residential garage door and commercial overhead door applications, for instance. Each overhead door assembly  10  is an integral unit and includes a vertically moveable door  20  which itself is comprised of at least one hollow door section  31  suitable for enclosing therein the components of a counterbalancing mechanism  40  as described in greater detail below.  
      Door  20  is also vertically movable relative to a doorway between a closed or blocking position and an open or stowed position. In the illustrated embodiment, door  20  is comprised of a plurality of hingedly attached door sections  30  oriented in series, one on top of another, together with hingedly attached hollow door section  31 . As is customary in the art, door  20 , or each door section  30  and hollow door section  31 , is comprised of a front panel  22 , a rear panel  24 , and opposed lateral edges  26   a ,  26   b . A plurality of side-mounted guiding elements or lateral end members in the form of rollers  38  are positioned along lateral edges  26   a ,  26   b  of door sections  30  and hollow door section  31  for rolling engagement within a pair of guide tracks  1   a ,  1   b  mounted on each side of the doorway. In the immediate embodiment, each guide tracks  1   a ,  1   b  includes a first segment  2  which extends substantially vertically along the sides of the doorway, a second overhead segment  3  which extends substantially horizontal with respect to the doorway, and a curved segment  4  there between. Each guide track  1   a ,  1   b  receives guiding members or rollers  38  of door  20 , in a centrally disposed channel  8  which runs at least along the entire length of first segment  2 .  
      Although door  20  described and illustrated in  FIG. 1  is comprised of a sectional door having a plurality of hingedly attached door sections  30 , it will be readily appreciated by those skilled in the art that door  20  may take other forms without departing from the scope or spirit of the present invention. By way of non-limiting example, door  20  may alternatively be in the form of a single hollow door section (i.e., a non-hinged door structure). It will also be appreciated that the guiding members or rollers  38  for door  20  may take other forms including, for example, pins with rounded heads which are received by guide tracks  1   a ,  1   b . Alternatively, lateral edges  26   a ,  26   b  of hingedly attached door sections  30  could form the guiding members by being directly received in the guide tracks  1   a ,  1   b . In addition, the guide tracks  1   a ,  1   b  may alternatively be completely straight and vertical, as opposed to curved. In this way, door  20  may either have a substantially horizontal closed position, or a substantially vertical closed position, as with vertically-storable doors.  
      Reference now being made to  FIG. 2 , counterbalancing mechanism  40  is provided for counteracting the effects of gravity on door  20  as it moves between the open (not shown) and closed positions. Counterbalancing mechanism  40  may be constructed in numerous ways without departing from the spirit of the subject invention which is to house such an assembly inside of the door itself. In a first embodiment, counterbalancing mechanism  40  is comprised of a pair of springs  42   a ,  42   b  which are mounted around a support shaft  44 , a pair of spaced-apart cable drums  46   a , 46   b  which are mounted at opposite ends of support shaft  44 , and a pair of tensioning members  50   a , 50   b  which in this case take the form of cables. Support shaft  44  is rotatably mounted to door  20  at opposite ends of support shaft  44  by shaft support bearings  43   a ,  43   b . Spring  42  may be a helical torsion spring or other suitable spring or tensioning device known to those skilled in the art. One end of each spring  42   a ,  42   b  in relation to other end is fixed onto cone  49   a ,  49   b  which is set to the torsion bar. The opposite ends of each spring  42   a ,  42   b  terminate in stationary mounting cones  45   a ,  45   b  with corresponding shaft support bearings  43   c ,  43   d . As may be appreciated a single spring  42  ( FIG. 3 ) may be substituted for pair of springs  42   a ,  42   b . Support shaft  44  is rotatably mounted within hollow door section  31 , and cable drums  46   a ,  46   b  are substantially aligned with the opposed lateral edges  26   a ,  26   b  of hollow door section  31 . In this case, a length of each cable  50   a ,  50   b  is wound at one end about its respective cable drum  46   a ,  46   b . Each cable  50   a ,  50   b  then extends downward to the lowermost corners of hollow door section  31  where it passes through pulley  70   a ,  70   b  and is then redirected out of door  20  through aperture  33   a ,  33   b  and upward to a fixed point  80   a , 80   b  above the doorway. Although tensioning members  50   a ,  50   b  are described herein as cables, it will be appreciated by those skilled in the art that other forms of tensioning members  50   a ,  50   b  may alternatively be used including, for example, cords, ropes, belts, chains, and the like.  
      Thusly described, counterbalancing mechanism  40  not only controls the descent of the door  20  as it moves downwardly from the open position, but also makes the door  20  easier to raise from the closed position. For example, when the door  20  moves towards the closed position, the support shaft  44  rotates about its axis, the tensioning members  50   a ,  50   b  progressively unwind from the cable drums  46   a ,  46   b , and springs  42   a ,  42   b  (or spring  42 ) becomes increasingly torsioned. This torsioning of spring  42   a ,  42   b , in turn, causes tensioning members  50   a ,  50   b  to exert a force on door  20  which partially counteracts its weight. In this way, counterbalancing mechanism  40  controls the descent of door  20  as it moves either by manual force, motive force, or gravity from the open position. Conversely, when door  20  is lifted from the closed position, the energy stored in springs  42   a ,  42   b  provides a restoring force which makes it easier to elevate door  20 . In both instances, tension is continuously maintained in tensioning members  50   a ,  50   b  as door  20  moves between the open and closed positions. If, however, the tensioning members  50   a ,  50   b  were to fail, become slack, or otherwise lose tension, the counterbalancing mechanism  40  would no longer be able to control the upward or downward movement of the door  20 .  
      Although a counterbalancing mechanism  40  with a torsion springs  42   a ,  42   b  is specifically shown and described herein, it will be readily appreciated by those skilled in the art that virtually any type of counterbalancing mechanism may alternatively be used-without departing from the scope or spirit of the present invention. For example, the counterbalancing mechanism  40  may instead include extension springs, compression springs, leaf springs, or the like.  FIGS. 3, 4  and  5  depict alternate embodiments of counterbalancing mechanism  40  and are described in detail below.  
      It may be readily appreciated that the diameter of each cable drum  46   a ,  46   b  is limited to the depth of hollow door section  31 . Accordingly, cable drums  46   a ,  46   b  will have a relatively limited capacity. When the gage and/or length of tensioning members  50   a ,  50   b  exceed the capacity of their respective cable drums  46   a ,  46   b  the addition of intermediate cable spooling apparatus may be employed to resolve this problem as described in detail below. Reference now being made to  FIG. 3 , an alternate counterbalancing mechanism  140  is provided for counteracting the effects of gravity on door  120  as it moves between the open (not shown) and closed positions. In this next embodiment, counterbalancing mechanism  140  is comprised of a spring  142  which is mounted around a support shaft  144 , a pair of spaced-apart cable drums  142   a ,  142   b  which are mounted at opposite ends of support shaft  144 , and a pair of tensioning members  150   a ,  150   b  which in this case take the form of cables. Spring  142  may be a helical torsion spring or other suitable spring or tensioning device known to those skilled in the art. Further, spring  142  may be comprised of a pair of springs (not shown) which are mounted around support shaft  144  as arranged in  FIG. 2  above. Gear reduction device  148  may be used to apply tension to spring  142  (or springs  142   a ,  142   b ) by rotating one end of spring  142  in relation to its opposite end which is fixed onto cone  149  which in turn is fixed to support shaft  144 .  
      Support shaft  144  is rotatably mounted to door  20  at opposite ends of support shaft  144  by shaft support bearings  143   a ,  143   b . Support bearings  143   a ,  143   b  are mounted to vertical stiles  136   a ,  136   b  which reinforce the structural integrity of door  120  generally and hollow door section  131  in particular. Cable drums  146   a ,  146   b  are substantially aligned with vertical stiles  136   a ,  136   b  of hollow door section  131 . In this case, a length of each tensioning member  150   a ,  150   b  is wound at one end about its respective cable drum  146   a ,  146   b . Each tensioning member  150   a ,  150   b  then extends downward to pulleys  160   a ,  160   b  which are mounted to the bottom of hollow door section  131  below each cable drum  146   a ,  146   b , and then to the inner races  152   a ,  152   b  of dual race cable drums  147   a ,  147   b  about which the opposite ends of tensioning members  150   a ,  150   b  are wound. A second pair of tensioning members  151   a ,  151   b  are partially wound about the outer races  153   a ,  153   b  of dual race cable drums  147   a ,  147   b  and run to the lowermost corners of hollow door section  131  where they pass through pulleys  170   a ,  170   b  and are then redirected out of door  120  through apertures  133   a ,  133   b  and upward to a fixed points  180   a ,  180   b  above the doorway. The diameter of outer race  153   a ,  153   b  may vary relative to the diameter of inner race  152   a ,  152   b  of each dual race cable drum  147   a ,  147   b  to adjust overall tension and to provide a mechanical advantage. A preferred ratio of diameters of outer race  153   a ,  153   b  to inner race  152   a ,  152   b  is 4:1, although any diameter of outer race  153   a ,  153   b  which is greater than the diameter of inner race  152   a ,  152   b  will provide a desired mechanical advantage. Although tensioning members  150   a ,  150   b  and  151   a ,  151   b  are described herein as cables, it will be appreciated by those skilled in the art that other forms of tensioning members  150   a ,  150   b  and  151   a ,  151   b  may alternatively be used including, for example, cords, ropes, belts, chains, and the like.  
      As shown in  FIG. 4 , yet another counterbalancing mechanism  240  includes a relatively horizontal torsion spring  290  within hollow door section  231  and removably attached at one end to a fixed location therein via spring attachment means  279 . Spring attachment means  279 , herein depicted as a hook, may of course take numerous other forms. Dual pulley  292  is attached by conventional means to the other end of torsion spring  290  which said end is free-floating and supported only by tensioning members  250   a , 250   b  as described below. A pair of tensioning members  250   a , 250   b  share a common point of origin along the length of vertical stile  236  to which they are anchored using an S-hook or other suitable means. Tensioning members  250   a , 250   b  together are threaded through dual pulley  292 . Tensioning member  250   a  is then directed through optional first stile pulley  294 , which is rotatably mounted at a second point along the length of vertical stile  236 , and thereafter through corner pulley  270   a , out of door section  231  via aperture  233   a , and then upward to fixed point  280   a  above door  220 . In like fashion, tensioning member  250   b  emerges from dual pulley  292  and is then threaded through second stile pulley  296 , which is rotatably mounted at a third point along the length of vertical stile  236 , and thereafter through corner pulley  270   b , out of door section  231  via aperture  233   b , and then upward to fixed point  280   b  above door  220 .  
      As shown in  FIG. 5 , another counterbalancing mechanism  340  a relatively horizontal torsion spring  300  with pulleys  302   a ,  302   b  attached at either end and free-floating and suspended within hollow door section  331 . Pulleys  302   a ,  302   b  are herein depicted as attached to torsion spring  300  by means of a hook, but, the attachment means may, of course, take numerous other forms. A pair of tensioning members  350   a , 350   b  originate attachment points  379   a ,  379   b  located along the interior sides  326   a ,  326   b  of hollow door section  331  to which they are anchored using an S-hook or other suitable means. Tensioning members  350   a ,  350   b  could alternatively anchored to vertical stiles or other suitably secure point within hollow door section  331 . Tensioning members  350   a ,  350   b  are threaded through pulleys  302   a ,  302   b  and thereafter to pulleys  370   a ,  370   b , out of the hollow door section  331  via aperture  333   a ,  333   b  to fixed points  380   a ,  381   b  above door  320 .  
      As shown in  FIG. 6 , depicting a side view of the lower corner of hollow door section  31 , the change in direction of the tensioning member  50  as it passes out of hollow door section  31  through aperture  33  may be accomplished through an idler cam  110 . As described above tensioning member  50  passes around pulley  70  out of aperture  33  to fixed point  80 . Tension on tensioning member  50  provided by spring  115  will cause the idler cam to pivot in accordance with the linear path of the cable and absorbs any slackening of tension on the cables. This provides a smooth transfer of direction from pulley  70  to pulley  112  to pulley  113 .  
      Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.  
      Furthermore, the skilled artisan will recognize the interchangeability of various features from different embodiments. In addition to the variations described herein, other known equivalents for each feature can be mixed and matched by one of ordinary skill in this art to construct various components of the invention.  
      Although this invention has been disclosed in the context of certain preferred embodiments and examples, it therefore will be understood by those skilled in the aft that the present invention extends beyond the specifically disclosed embodiments and/or uses of the invention and obvious modifications and equivalents thereof. Thus, it is intended that the scope of the present invention herein disclosed should not be limited by the particular disclosed embodiments described above, but should be determined only be a fair reading of the claims that follow.