Abstract:
A garage door movement apparatus comprising a garage door vertically movable in tracks to open and close a garage door opening. A jack shaft may be mounted horizontally above the door opening and support a sprocket disposed thereon. A chain may be connected to the door near a bottom thereof and engaged with the sprocket. A spring may be disposed about the jack shaft to provide rotation forces to act against the weight of the door. A track for carrying the garage door is mounted near the garage door opening and has at least a vertical section. In order to convey downward forces on the door from the sprocket, the chain between the sprocket and the door bottom may include a substantially vertical section of a chain guide, which is disposed beneath the sprocket in a direction substantially parallel with the door track.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to barrier movement systems, in particular to systems using jack shaft garage door counterbalance apparatus.  
         BACKGROUND  
         [0002]    Various types of barrier movement systems such as garage door operators comprise a door opening, a door to cover and uncover opening and guides to keep the door in place. The barriers which open and close vertically are normally relatively heavy and must be counterbalanced so that people or small electric motors can generate sufficient force to open or close the door.  
           [0003]    One type of counterbalance consists of a jack shaft mounted horizontally above a door opening with a tension spring around the shaft. A cable is attached to each edge of the bottom of the door and wound around drums at each end of the jack shaft. The jack shaft spring is adjusted to provide rotation force to the jack shaft in a direction to provide an upward force to the door with the cable. In this way the upward force required to raise a 200 lb. door may be reduced to 20-30 lbs. The drums on the jack shaft ends may include cable receiving grooves to properly gather and pay out the cable during the door opening and closing. As the weight of the door is the only force acting to keep the cable taut, rapid changes in the apparent door weight can cause the cable to come off the drum or coil improperly across itself.  
           [0004]    The jack shaft arrangement has also been used for automated door movement by controlling a motor which is connected to rotate the jack shaft. In the case of a conventional jack shaft arrangement the addition of a motor alone does not hold the door in the closed position as is the case with an automated rail and trolley drive system. The door needs a lock to prevent break-in, as opening the door from the outside only requires overcoming the balanced weight of the door e.g., 20-30 lbs.  
           [0005]    Numerous attempts have been provided to operate the garage door by motorizing the jack shaft to turn the drum and pull the door up by cable. Conventional automatic garage door operators are electromechanical devices, which initiate movement of the garage door to block and unblock a garage door opening in response to actuating electrical signals. A known example of a garage door is a conventional sectional overhead garage door, which comprises a plurality of parallel hinged panels pivoted along pivot axes parallel to the hinge axes, and the pivot axle structures which guided so that the door can follow the locus of the guides. The door normally employs an opening mechanism comprising a motor driving a spring-loaded jack shaft positioned parallel with the upper edge of the door and rotatably mounted above the garage door frame. Balancing the conventional overhead garage door is normally achieved by attaching cables from both sides of the bottom of the door to drums located near each end of the jack shaft. The pull-up cable is taken up on the drum lifting the garage door. The door is closed by the combination of the restoring force of the torsion spring releasing the pull-up cable and the portion of the weight of the door which is unsupported by the tracks or other structures carrying the door.  
           [0006]    Therefore, a need exists for a reliable mechanism for a garage door movement apparatus.  
         SUMMARY  
         [0007]    This need is met and the objects are achieved with the present invention. An embodiment is directed to a garage door movement apparatus comprising a garage door having weight which is vertically movable in tracks to open and close a garage door opening. A jack shaft is mounted horizontally above the door opening and supports a sprocket disposed thereon. A chain is connected to the door near a bottom thereof and engaged with the sprocket. Further, a spring disposed about the jack shaft to provide rotation forces to act against the weight of the door. A track for carrying the garage door is mounted near the garage door opening and has at least a vertical section. In order to convey downward forces on the door from the sprocket, the chain between the sprocket and the door bottom may include a substantially vertical section of a chain guide, which is disposed beneath the sprocket in a direction substantially parallel with the door track.  
           [0008]    Preferably, the first end of the chain is connected to the bottom of the door, and the center portion of the chain is engaged with the sprocket and may be moved (stored) within a horizontal section of the chain guide when the door is opening. In one embodiment a rolling chain with a chain guide is used to drive the door. In another embodiment a drive chain is a push-pull chain comprising asymmetrical links for inhibiting bending of the chain. The preferred shape of the asymmetric links is such that to form a rigid thrust mechanism by interlocking the adjacent links when the chain is under compression. The interlocking of the chain links prevents movement of the chain past straight configuration. The garage door opens when the sprocket rotates pulling up the drive chain. It is preferable that the thrust mechanism formed by the guided roller chain on the push-pull chain under compression pushes the door to a closed position and keeps the door closed.  
           [0009]    Another embodiment provides powered opening and closing of the door by a reversible electric motor, and the power output of the electric motor is preferably connected to the door by rotating the jack shaft. Embodiments are described in which the rolling chain provides a driving connection between the motor shaft and the sprocket.  
           [0010]    The invention may be described with greater clarity and particularity by reference to the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is a perspective view of a garage with a garage door in closed position;  
         [0012]    [0012]FIG. 2 is a perspective view taken from the same position as FIG. 1 but showing the garage with a partially open door driven by a garage door movement apparatus;  
         [0013]    [0013]FIG. 3 is a perspective view taken from the same position as FIG. 1 but showing the garage with the door in fully open position;  
         [0014]    [0014]FIG. 4 is a side elevation view of a portion of the garage door movement apparatus with the garage door in closed position;  
         [0015]    [0015]FIG. 5 is a view of a motorized door movement apparatus showing a roller chain engaged with a sprocket when the door is in open position;  
         [0016]    [0016]FIG. 6 is a view of the garage door movement apparatus showing a push-pull chain engaged with a sprocket when the door is in closed position;  
         [0017]    [0017]FIG. 7 is a perspective view of a chain which can convey compression forces;  
         [0018]    [0018]FIG. 8 is a transparent plan view of the chain of FIG. 7;  
         [0019]    [0019]FIG. 9 is a perspective view of a chain guide channel;  
         [0020]    [0020]FIG. 10 shows an end view of the chain guide of FIG. 9;  
         [0021]    [0021]FIG. 11 shows a chain guide into which a chain has been inserted;  
         [0022]    [0022]FIG. 12 is a perspective view of a sprocket drive for a roller chain without a jack shaft; and  
         [0023]    [0023]FIG. 13 is a perspective view of a sprocket drive for a thrust conveying chain without a jack shaft. 
     
    
     DETAILED DESCRIPTION  
       [0024]    Referring now to the drawings and especially to FIGS. 1-3, a garage door movement apparatus is shown therein. A garage has a garage door opening  14  and a movable sectional garage door  16 , which is associated with it. The garage door  16  shown in FIGS. 1-3 is a sectional door consisting of a plurality of rectangular panels  40 ,  42 ,  44  and  46 . The panels  40  and  42  are connected by a plurality of hinges  50 . Panels  42  and  44  are connected by a plurality of hinges  52 . Panels  44  and  46  are connected by a plurality of hinges  54 . The door is carried on a plurality of rollers in a pair of L-shaped tracks  60  and  62 . The exemplary L-shaped track  60  shown in FIG. 1 includes a vertical straight portion  64 , a curved portion  66  and a substantially straight horizontal portion  68  suspended by a hanger  90  from the ceiling of the garage. A plurality of rollers  70  positioned on shafts  74  (FIGS. 5 and 6), are attached to the door panels and ride in the track  60  and carry the door panels upward and downward. FIG. 1 shows the garage door in closed position. A jack shaft  22  is mounted horizontally above the door opening and supports a pair of sprockets  24  mounted on either end of the jack shaft to be turned with it. A drive chain  26  is engaged with each sprocket  24  to be pulled upward or pushed downward. Also mounted on the jack shaft  22  are torsion springs  18 , which perform a function of counterbalancing part of the weight of the door to reduce the power required to raise the door  16 . In the lowered position of the door  16  as shown in FIGS. 1 and 6, the springs  18  are wound to the maximum extent providing a lifting force to counter-balance the weight of the door and reducing the force to be applied to the door in order to lift it. In the elevated position of the door  16  as shown in FIGS.  3  and  5 , the springs  18  are partially unwound reducing the counter-balancing force provided. It is preferred that the drive chain is not formed into a loop, but rather has a first and second ends. The drive chain as described herein is a roller chain operating in a guide or a push-pull chain, but it is not limited to those types of chains.  
         [0025]    The chain  26  is used in tension to raise and lower the door and, in some situations discussed below, the chain is in compression to start the closing motion and to hold the door closed. One type of chain which can convey forces in compression is a push-pull chain. A portion of a representative push-pull chain is illustrated in perspective in FIG. 7 and in transparent plan in FIG. 8. The push-pull chain consists of a number of roller chain links  100  which may, for example, be bicycle chain links. The roller chain links  100  are coupled by asymmetrical links  103  by means of link pins  102 . The links  103  are connected to the roller links  100  so that when the chain is straight, as shown, a V-shaped protrusion  109  of each link  103  contacts a V-shaped notch  111  in the link adjacent to it. Thus, should forces be applied to bend the chain in the direction marked  107  no bending will occur and the chain will remain straight. Alternatively, if forces are applied in the direction  105  the chain is free to bend as any roller chain. The push-pull chain of FIGS. 7 and 8 can be bent around curves concave from directions  113 , but it cannot be substantially curved in the reverse direction.  
         [0026]    A roller chain can convey forces in compression when it is supported from both sides of its length to keep the chain from bending. Such support can be achieved by passing the chain through a channel of the type shown in FIGS. 9, 10 and  11 . The support provided by the channel permits the chain to be a thrust mechanism. The channel  120  is an extruded piece of rigid material such as aluminum or a hard plastic. An opening  122  of substantially rectangular cross section is present in the channel. A void  124  is left throughout the length of the guide  120  to provide access to the chain for connections. The void  124  results in two protrusions  127  and  129  extending toward the center of the top surface of the guide  120 . The protrusions can be used to provide anti-bend support to a roller chain. FIG. 10 is an end view of the guide  120  with a chain link  131 . The chain slides into the guide so that the protrusions  127  and  129  restrain the side to side movement of the chain rollers e.g.,  133 . When compression forces are applied to the chain in a guide  120  the chain does not bend and the forces are applied along the chain. It should be noted that a chain guide of the type discussed can be formed in curves and still permit compression forces to be conveyed by the chain. FIG. 11 shows a section of rail  120  having a chain therein.  
         [0027]    A first end  80  of the drive chain  26  is connected to the bottom panel  40  of the garage door shown in the open position in FIG. 5. In order to raise the door to a maximum height the connection between the chain end  80  and the door panel  40  is completed by means of a connector  89 . FIG. 5 shows the jack shaft sprocket  24  used with a guided chain. In order to stiffen the chain between the sprocket  24  and the door bottom, a chain guide consisting of portions  84 ,  85  and  86  is provided, a vertical portion  86  of which is disposed beneath the sprocket in a direction substantially parallel with portion  62  of the door track  60 . The chain guide  85  and  86  prevent the chain from bending as it is pushed by the drive mechanism when closing or securing the garage door. The center portion  82  of the chain  26  remains engaged with the sprocket  24  when the door is closed, and, when the door opens, the chain  26  moves within the horizontal section of the guide  84  as shown in FIG. 5, or is stored in a magazine ( 35  FIG. 1). The horizontal portion of the chain guide  84  is adjacent and substantially parallel to the door track portion  68 . In FIG. 5, an additional chain guide  31  is used to keep chain  26  on sprocket  24  and a chain guide  31  is used to keep chain  26  on a sprocket  28 .  
         [0028]    The automated garage door movement apparatus, includes a reversible electrical motor  30  drivingly connected to a jack shaft  22 . In operation, when the motor is energized, the jack shaft  22  rotates and the sprocket  24  mounted on the shaft and engaged with a drive chain  26  pulls the chain lifting the door. When the door  16  is lowered, the motor rotates in the opposite direction, and the sprocket  24  pushes the chain  26  downward. FIG. 5 shows the garage door movement apparatus using a portion of the roller chain as a drive chain. In this embodiment the roller chain  26  drivingly engages the sprocket  24  with a drive sprocket  28 . The motor  30  is connected (not shown) to rotate drive sprocket  28 .  
         [0029]    When the door is to be lowered, motor  30  is energized to rotate sprocket  28  in a counter clockwise direction, as shown, and chain  26  rotates sprocket  24  and jack shaft  22  and chain end  80  proceeds downward in guides  85  and  86 . The downward movement of the chain  26  moves the door downwardly. It should be mentioned that as the door leaves the open position shown in FIG. 5 the connector  89  becomes near vertical as the door bottom moves nearer the door opening. Also as the door is moving downwardly chain  26  will be withdrawn from the channel  84  or the chain magazine  35 . Any attempt to manually raise the door after it is closed requires that chain  26  be moved upwardly which would require rotation of sprocket  28 . The connection between motor  30  and sprocket  28  is substantially gear reduced so that the driving of sprocket  28  by chain  26  is a difficult task. When the door is to be raised, motor  30  is energized to rotate sprocket  28  in the clockwise direction which raises the chain end  80  and thus raises the door. In the preceding embodiment motor forces were applied to the chain by sprocket  28 . It is to be understood that the motor  30  could be connected to drive jack shaft  22  and sprocket  24  with out the intervening sprocket  28 . In such a case sprocket  28  might remain as an idler or it might be replaced by a guide channel.  
         [0030]    [0030]FIGS. 4 and 6 represent an embodiment in which a push-pull chain is used to move the door. As with the embodiment of FIG. 5 the chain  26  is connected by means of a connector  89  near the bottom of the door. Such is not specifically shown in FIG. 6 which illustrates the door  16  in its closed position. It should be mentioned that chain  26  of FIG. 6 is attached to the door so that the roller link portions  100  face into the garage. Chain  26  of FIG. 6 is thus free to bend around sprocket  24  to engage it. Chain  26  proceeds into a magazine  35  which accumulates the chain before it dangles into the garage. Magazine  35  may be an empty box to accumulate the chain or it may contain a reel which is lightly spring loaded to take up the free chain end. A guide member  37  is disposed over sprocket  24  to retain the chain  26  in contact therewith. Guide member  37  fits between the pairs of asymmetrical plates  103  and the roller links to guide chain  26 .  
         [0031]    When the door is to be raised motor  30  is energized to rotate sprocket  24  in a counter clockwise direction. The chain  26  applies raising force to the door and the free chain, from sprocket  24  is accumulated in the magazine  35 . When the door is to be moved to the closed position motor  30  is energized to rotate sprocket  24  in the clockwise direction. The push pull chain  26  acts as a thrust mechanism when being pushed down. As such, force is first applied to start movement of the door and to keep the door moving. The motor is stopped when the door is in the closed position. Should someone attempt to raise the door from the closed position upward forces would be conveyed by the chain  26  to the sprocket  24 . Rotating the motor  30  through its gear reduction by rotating sprocket  24  is a difficult task. Accordingly, the push-pull chain  26  helps to keep individuals from raising the door. Optionally, a guide member  39  may run the length of the door opening to provide structural support to push-pull chain  26 . Such a guide would in essence be an extension of guide  37  which covers sprocket  24 .  
         [0032]    The advantage of the push-pull chain with asymmetrical links is that when the chain is under tension, it can pull the door, and when the chain is under compression, it forms a rigid thrust mechanism by interlocking the adjacent links. The thrust mechanism pushes the door downward and holds it in the closed position preventing it from involuntary opening and brake-in by manually lifting the door from the outside.  
         [0033]    The preceding embodiments include a jack shaft mounted above the door opening to provide automatic drive as well as counterbalance for the door. FIGS. 12 and 13, show modifications of FIGS. 5 and 6 respectively, in which a jack shaft is not employed and a sprocket  24  is mounted above the door opening. The automatic drive force for the door is produced by motor  30  as in the preceding embodiments. Other means such as expansion springs (not shown) above the rails  60  and  62  may be used to counterbalance the door weight.  
         [0034]    While there has been illustrated and described particular embodiments, it will be appreciated that numerous changes and modifications will occur to those skilled in the art, and it is intended in the appended claims to cover all those changes and modifications which fall within the true spirit and scope of the present invention. By way of example, the drive chain is presented in the disclosed embodiments as a roller chain and a push-pull chain. The door movement apparatus can employ any other type of flexible chain means within the scope of the present invention.