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FIELD OF THE INVENTION  
       [0001]     The invention relates to a barrier movement or garage door operator, in particular, to a jack shaft operator having a coupling for connecting a power shaft to a jack shaft for operating the barrier or garage door.  
       BACKGROUND OF THE INVENTION  
       [0002]     In general terms, a barrier such as a garage door is installed on a pair of rails having generally vertical portions positioned proximate the sides of a garage opening and having generally horizontal portions extending away from the opening into the interior of the garage. The garage door is moved along the rails to shift between a generally closed position within the garage opening and between the vertical rail portions, and a generally open position away from the garage opening and between the horizontal rail portions. A garage door operator is used to drive the movement of the garage door between the open and closed positions.  
         [0003]     Currently, jack shaft garage door operators are well-known for driving the movement of a garage door. The door operator includes a generally vertically extending cable having a first end secured to a lower portion or panel of the garage door. The door operator exerts tension on the cable to lift and shift the garage door from the closed position to the open position. The cable has a second end connected to a pulley. In order to exert tension on the cable, the door operator rotationally drives the pulley so that the cable is wound around the pulley, thereby shortening the distance between the pulley and the cable first end, as well as between the pulley and the lower portion of the garage door being raised.  
         [0004]     The pulley is located on and secured with a jack shaft extending parallel to the garage opening. As the cable is attached to a lower portion of the door and within the rails, the pulley and jack shaft are positioned so that movement of the door does not interfere with operation of the pulley. The jack shaft is typically a torsion bar which can include either a coil spring or extension springs to provide a spring bias to the pulley tending to draw the garage door toward the open position. However, the bias is insufficient to overcome the weight of the door without additional power being provided to the pulley.  
         [0005]     The additional power for overcoming the door weight to open the garage door is provided to the pulley by a drive system, typically an electric motor driving an output power shaft extending from a housing of the drive system. The power shaft and pulley are operably coupled with a transmission system which may include a belt or drive chain for driving sprockets respectively fixed on the power shaft and jack shaft or its pulley.  
         [0006]     The drive system is mounted to a wall in a position outside of the opening and rails. The power shaft extends from the housing a short distance toward a first rail with its sprocket located on and end thereof. The drive chain extends vertically, either upwardly or downwardly, between the power shaft sprocket and the jack shaft sprocket. Accordingly, the jack shaft must extend beyond at least one of the rails, and the sprockets are aligned to rotate generally in the same plane.  
         [0007]     Such an arrangement presents a number of issues. Because of the transmission including the sprockets and chain, the system has particular space requirements for installation. A certain precision must be provided in aligning the sprockets to generally rotate in the same plane, and a certain amount of precision must be provided in mounting the drive system to provide the chain with the proper amount of tension between the sprockets.  
         [0008]     Additionally, the sprockets have an annular hub or collar, and securing the sprocket hub to their respective shaft presents further problems. One approach for securing the hub is with set screws which are known to loosen over time, allowing the sprocket to slip. Set screws can also compress a hollow shaft or bar, leading to stress concentrations and failure of the system including twisting or deflection of the shaft.  
         [0009]     Another manner for securing the sprocket to a shaft is with some type of keyed mating such as drilling a hole through the hub and its shaft, and inserting a pin therein. This method is labor intensive, incurring additional costs in machining and milling the surfaces, and stress concentrators may be produced which may lead to damage and failure. Additionally, such mating reduces the flexibility in mounting the components of the system, such as the drive system, as the sprockets are to be aligned to rotate in the same plane.  
         [0010]     Some of the problems with securing the sprockets may be overcome by using a solid shaft. However, a solid shaft significantly increases the cost of the component, as well as significantly increases the weight such that an increase in the operational torque of the motor is needed.  
         [0011]     Accordingly, there has been a need for an improved jack shaft door operator.  
       SUMMARY  
       [0012]     A jack shaft barrier movement or garage door operator is disclosed herein for opening and closing a movable barrier or garage door. The garage door operator includes an electric motor for rotationally driving a power shaft operably connected to a jack shaft having a pulley thereon. The pulley has a cable secured thereto such that rotation of the jack shaft rotates the pulley and causes the cable to be wound around the pulley. An end of the cable is secured to a lower portion or panel of the garage door so that winding of the cable around the pulley draws the lower portion of the garage door towards the pulley, thereby lifting the door and moving the door along its track or rails from a closed position to an open position.  
         [0013]     The jack shaft and the power shaft are connected by a compression coupling. In this manner, the jack shaft and power shaft are fixed relative to each other. Each shaft has a coupling end that is inserted into a portion of the coupling and is compressed therein. This eliminates the need for the sprocket system and its above-described problems. For instance, the coupling is compressed in a radially inward manner against a entire circumference of the shaft, avoiding the issues of the set screws or keyed mating. The coupling is removable and may be placed on either end of the shaft, facilitating different mounting conditions and not requiring a pre-drilled hole in the shaft for pinning a sprocket thereon. Elimination of the belt or chain drive eliminates tensioning issues with the chain drive, and allows the drive system to be installed by simply aligning the shafts relative to each other. Alignment of the shafts is achieved easily by securing the shafts in the coupling. As the sprockets are not necessary, alignment of the sprockets for co-planar rotation is not necessary.  
         [0014]     The drive system can be placed in a number of positions by securing the shafts directly with the coupling. For instance, when lateral clearance outside of the rails is minimal, the jack shaft can be shortened and the drive system can be located above the door opening without needing to be offset a distance to provide for the sprocket and chain transmission system. In addition, the space requires for the operator are reduced as the drive system can be mounted at the end of the jack shaft and close to the rail.  
         [0015]     In one form, the coupling is a double split-ring, one split-ring for each of the shafts to be connected by the coupling. Both rings are joined to form a base portion and have respective compressive portions. In one form, the rings have different internal diameters sized generally for respective shafts having different external diameters, such as the jack shaft and output power shaft. Accordingly, a shoulder is formed between the rings. In some forms, the larger of the shafts may be inserted in the larger internal diameter ring of the coupling to a depth to contact the shoulder and be secured therein. The other shaft is then inserted in the other ring to an appropriate depth and secured therein. In the event the larger shaft is hollow, the smaller shaft may be received by both the coupling and the larger shaft.  
         [0016]     In some forms, the coupling is a unitary member having a base and a pair of deflectable portions in the form of arms extending from the base. One end of each arm is secured to the coupling base, and the other end is generally free prior to installation. To couple the shafts, the free ends of the arms are secured relative to the base. A shaft is inserted within the base and an arm, and the arm free end is drawn toward the base such that an interior surface of the base and arm compress radially inwardly on the outer, circumferential surface of the shaft.  
         [0017]     In other forms, the coupling has a partial-circular base and two partial-circular arms, each having two free ends that are securable to the base to form a complete circle. Each shaft may be positioned between an arms and the base, and the arm is then secured to the base to compress the circumference of the shaft.  
         [0018]     The coupling generally defines an internal cavity for receiving the ends of the jack shaft and output power shaft such that the coupling provides an overlapping connection with of the shafts. Each shaft may have a predetermined outer diameter, and the internal cavity may have a predetermined inner diameter generally sized with respect to the diameters of the shafts. Once the shafts are received therein, at least a portion of the coupling is compressed against the shaft. In one form, the coupling includes compressing portions that are deflected toward a base to compress the shafts therebetween are moved toward a base to reduce size of the internal cavity. In another form, the coupling includes compressing portions that are moved toward a base to compress the shafts therebetween. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]     In the drawings,  FIG. 1  is fragmentary perspective view of a garage having a garage door in a closed position with a jack shaft garage door operator attached to the garage door for moving the door between the closed position and an open position, the door operator including a drive system and an output shaft connected to a jack shaft by a coupling;  
         [0020]      FIG. 2  is a first fragmentary perspective view of the coupling connected to the jack shaft and to the output shaft, and the door operator having a housing partially cut-away to show the output shaft;  
         [0021]      FIG. 3  is a prior art perspective view of a door operator having an output shaft operably connected to a shaft by a sprocket and chain or belt drive transmission;  
         [0022]      FIG. 4  is a second fragmentary perspective view of the door operator showing the coupling secured on the jack shaft;  
         [0023]      FIG. 5  is a third fragmentary perspective view showing the coupling secured on the jack shaft, the door operator housing and output shaft in phantom, and the jack shaft extending through a hollow center of the output shaft;  
         [0024]      FIG. 6  is a first perspective view of a form of the coupling showing a base portion and a pair of deflectable portions;  
         [0025]      FIG. 7  is a second perspective view of the coupling of  FIG. 5  showing clamping bores;  
         [0026]      FIG. 8  is a first side elevational view of the coupling of  FIG. 5  showing internal diameters of the coupling;  
         [0027]      FIG. 9  is a second side elevational view of the coupling of  FIG. 5  showing a gap between a free end of the deflectable portions and the base; and  
         [0028]      FIG. 10  is a second form of a coupling showing a base and a pair of compression portions securable to the base. 
     
    
     DESCRIPTION  
       [0029]     Referring initially to  FIG. 1 , a garage door operator  20  having a shaft coupling  30  embodying aspects of the present invention is depicted. The door operator  20  is secured to an interior wall  3  of a garage  1  proximate a garage opening  2 . The garage opening  2  is covered by a garage door  4 , depicted in a closed position. The door operator  20  functions to move the garage door  4  from the closed position to an open position to allow passage through the garage opening  2 . The garage door  4  is represented as having four panels  5  connected by hinges  6 , and has wheels (not shown) secured to the lateral sides  5   a ,  5   b  of the panels  5 . The wheels are located within rails  7   a ,  7   b  having a generally vertical sections  8  secured to the wall  3  and to a garage floor  11 , and having generally horizontal sections  9  secured to a ceiling  12 . When the garage door  4  is moved to the open position, the panels  5  are guided along the rails  7   a ,  7   b  by the wheels. The rails  7   a ,  7   b  further have curved transition portions  10 , and the panels  5  pivot relative to each around the hinges  6  to allow the panels  5  to move between the vertical and horizontal sections  8 ,  9 .  
         [0030]     The door operator  20  includes a jack shaft  22  positioned above the opening  2  and a drive system  24  positioned lateral to the opening  2 . The drive system  24  includes an output power shaft  26  connected to the jack shaft  22  by the coupling  30 . Thus, when the power shaft  26  is rotated, such as by an electric motor  28  (see  FIG. 3 ), the jack shaft  22  is directly rotated to raise the garage door  4 , as will be discussed below.  
         [0031]     As can be seen in  FIGS. 2 and 5 , the drive system  24  includes a housing  40  secured to the wall  3 , such as by a bracket  42  ( FIG. 1 ). The drive system  24  includes the electric motor  28  providing a sufficient torque for moving the garage door  4 . As depicted, the motor  28  is operably connected to the power shaft  26  with a belt or chain  46  to a sprocket  48  or the like secured to the power shaft  26 . As is known in the art, the electric motor  28  has a rotor (not shown) rotationally driving a motor axle (not shown) having an output sprocket or pulley (not shown). It should be noted that the motor  28  alternatively may be alternatively a direct drive motor with the power shaft  26  being the motor axle, or the motor  28  may be connected to the power shaft  26  via another transmission system, such as a geared transmission. A desired gear ratio for providing a desired speed and torque from the motor to the power shaft can be produced by proper selection of the size of the sprocket  48  relative to the output sprocket, or by a geared transmission, for instance.  
         [0032]     As shown in  FIGS. 1,2  and  5 , the jack shaft  22  and the power shaft  26  are co-axially aligned. More specifically, the coupling  30  receives an end of each of the power shaft  26  and jack shaft  22  to secure the shafts  22 ,  26  together in the co-axial arrangement. In this manner, rotation of the power shaft  26  causes equal rotation of the jack shaft  22 , as will be described below.  
         [0033]     In contrast, a prior art operator  50  is shown in  FIG. 3  without the coupling  30 . The prior art operator  50  includes a jack shaft  52 , and a drive system  54  for rotating the jack shaft  52  to move the garage door  4 . The operator  50  includes a housing  56  and an electric motor  58  coupled to a power shaft  60 , with or without a chain drive (not shown) within the housing  56 . The power shaft  60  extends from the housing  56  towards the garage opening  2  and includes a sprocket  62  secured thereto. The sprocket  62  drives a chain or belt  64  connected to a sprocket  66  located on the jack shaft  52 . As can be seen, the position of the prior art operator  50  is offset from the jack shaft  52 , requires an increased number of components than the door operator  20  of the present invention, requires alignment of the sprockets  62 ,  66  to rotate in a common plane, requires tensioning of the chain  64 , and requires securing the sprockets  62 ,  66  to their respective shafts  52 ,  60 . The operator  20  of the present invention each of these problems is reduced or eliminated by use of the coupling  30 .  
         [0034]     Referring to  FIGS. 2 and 4 , the operator  20  is provided with a pulley  70  and cable  72  to raise or lower the garage door  4 . The pulley  70  is attached to the jack shaft  22 , as can be seen in  FIG. 4 , while the cable  72  has a lower end  74  connected at a lower portion  76  of the garage door  4 , such as the bottom panel  5   c.  The cable  72  has a portion wound around the pulley  70  and secured thereto. When the jack shaft  22  is rotated, the pulley  70  is also rotated so that the cable  72  is either payed-out from or wound-up on the pulley  70 . That is, when the pulley  70  rotates in a first direction, the cable  72  is wound around the pulley  70  so that the distance from the pulley  70  to the cable lower end  74  is shortened and the door lower portion  76  is drawn toward the pulley  70 . When the pulley  70  is rotated in a second direction opposite from the first, the cable  72  is payed-out from the pulley  72  so that the door  4  is lowered.  
         [0035]     The pulley  70  is positioned close to a support bracket  80  secured to a rail frame  82 , itself secured with the rail  7   a . The support bracket  80  includes a bearing  84  for allowing rotation of the jack shaft  22  within the support bracket  80 . The bracket  80 , frame  82 , and bearing  82  provided support for the jack shaft  22 . With reference to  FIG. 1 , a support bracket  80  is provided at preferably both ends of the jack shaft  22  and secured to each rail  7   a ,  7   b . The pulley  70  is preferably proximate the support bracket  80  to reduce the moment arm or torque exerted by the tension on the cable during operation. In the prior art operator  50  ( FIG. 3 ), deflection of the jack shaft  22  due to tension on the cable  72  may cause the sprocket  66  to deflect out of its proper plane of rotation, resulting in excessive wear against the chain  64  and possibly cause the chain  64  to jump from the sprocket  66 .  
         [0036]     By eliminating the sprockets  62 ,  66  of the prior art operator  50 , any deflection experienced is transmitted directly through to the power shaft  26  where it has minimal effect. The power shaft  26  is relatively short and is secured within the housing  40  by a pair of bearings  90  positioned at each end  92  of the power shaft  26 . In this manner, the power shaft  26  is constrained from shifting or deflecting, thereby serving to constrain the jack shaft  22  from deflection. Significant stresses exerted on the power shaft  26  would, regardless, be transmitted to the wall  3  by the bracket  42 .  
         [0037]     With specific reference to  FIG. 5 , the power shaft  26  and housing  40  are shown in phantom. In some forms, one of the shafts  22 , 26  and preferably the power shaft  26  may be hollow to provide a cavity  96  therein. The jack shaft  22  may be inserted through the coupling  30  and further into the cavity  96 . This serves to further join the jack shaft  22  and power shaft  26  for rotation and relative securement, as well as reducing effects of deflection. Additionally, this facilitates different mounting conditions by reducing the need for precisely measured shafts and allows the drive system  24  to be mounted close to the rail  7   a .  
         [0038]     Turning now to  FIGS. 6-9 , a form of the coupling  30  for securing the power shaft  26  with the jack shaft  22  is depicted. Generally speaking, the coupling  30  is a split ring having a gap  100  so that the shafts  26 ,  22  may be received within the coupling  30 , whereupon the coupling  30  is compressed to reduce or eliminate the gap  100 . This compression applies radial compressive force around an entire circumference of each shaft  22 ,  26  located therein. The above-described problems with using set screws and keyed mating are thus eliminated, and the coupling  30  is suitable for use with both solid and hollow shafts without distorting or damaging the shaft and without creating stress concentrations.  
         [0039]     More specifically, the coupling  30  is formed as a double split-ring where the rings are joined together for a base portion  102 . The coupling  30  generally forms a C-shape and with base portion  102  generally formed as a half C-shape. A pair of generally parallel compressing portions or arms  104   a ,  104   b  are formed integrally with the base  102  and complete the C-shape having the gap  100 . Each arm  104   a ,  104   b  has a respective width  106   a ,  106   b , and the widths may be identical or one may be larger. As shown, arm  104   a  has a smaller width  106   a  than the width  106   b  of the other arm  104   b.    
         [0040]     The coupling  30  has an internal diameter  108  for receiving the shafts  22 , 26  therein. In the preferred embodiment, the coupling  30  has separate internal diameteral portions  108   a ,  108   b  generally sized for the power shaft  22  and jack shaft  26 , respectively. As can be seen, the diametral portion  108   a  is larger than the diametral portion  108   b  so that the power shaft  22  may have a larger diameter than the jack shaft  26 . The power shaft  22 , in the form including the cavity  96 , may receive the smaller jack shaft  26  within the cavity  96 , and thus requires the larger diametral portion  108   a  within the coupling  30 . Alternatively, the shafts  22 ,  26  may simply having different diametral sizes, in which case a coupling designed to compress the shafts  22 ,  26  in a generally distributed manner around the shaft circumferences is desirable. A shoulder  110  is formed between the larger and smaller diametral portions  108   a ,  108   b . During installation, the larger of the shafts  22 ,  26  may be inserted into the coupling  30  while using the shoulder  110  as a stop. The larger shaft may then be secured, and the other shaft then inserted and secured. Thus, the coupling  30  provides an overlapping connection to the ends of each shaft  22 ,  26   
         [0041]     In order to secure the coupling  30 , holes are provided for insertion of fasteners  124  (see  FIG. 4 ). The arms  104   a ,  104   b  are each provided with a hole  120 , and the base  102  is provided with a two holes  122 , each aligned with one of the respective holes  120  of the arms  104   a ,  104   b . In the preferred embodiment, the fasteners  124  are threaded bolts. Either the holes  120  or holes  122  is an insertion hole having a larger diameter than the other holes and larger than the thread profile of the fasteners  124  so that the fastener  124  simply passes through the insertion hole. The other of the holes  122 ,  120  is preferably threaded to receive the fastener therein in threaded engagement. To secure the coupling  30  on the shafts  22 ,  26 , the fasteners  124  are received by the insertion hole, either hole  120  or  122 , and threads into the hole aligned with the insertion hole. As the fasteners  124  thread in, the arms  104   a ,  104   b  are compressed inwardly to compress on the shaft  22 , 26 , and to reduce the gap  100  between the arms  104   a ,  104   b  and the base  102 .  
         [0042]     A second form of the coupling is depicted as coupling  130  in  FIG. 10 . The coupling  130  is similar to the coupling  30  in operation. However, the coupling  130  has a base  132 , generally a half C-shape, and two arms  134   a ,  134   b , similar to arms  104   a ,  104   b , that are not integrally formed with the base  132 . Instead, the arms  134   a ,  134   b  are secured to the base  132  at both ends  135 ,  137  of each arm  134 . Accordingly, the base  132  is provided with holes  140 , the arms  134  are provided with holes  142  which are aligned with the holes  140 , and the above-described fasteners  124  are received by the holes  140 ,  142  to secure the arms  134  to the base  132  to compress the shafts  22 ,  26  within the coupling  130 .  
         [0043]     While the invention has been described with respect to specific examples including presently preferred modes of carrying out the invention, those skilled in the art will appreciate that there are numerous variations and permutations of the above described systems and techniques that fall within the spirit and scope of the invention as set forth in the appended claims.

Summary:
A barrier movement or garage door operator has a jack shaft connected to an output shaft delivering power to move a barrier or garage door between open and closed positions, the jack shaft and output shaft being connected by a coupling. The coupling, jack shaft, and output shaft are fixed relative to each other. The coupling connects the jack shaft and output shaft for rotation around a common axis. The coupling receives a portion of the jack shaft and output shaft for securing the shafts within the coupling by compressing against an outer surface of each shaft. The shafts may be cylindrical, and the compressive force may be distributed around the cylindrical outer surface of the shafts. The coupling may have a portion sized to correspond to respective predetermined diameters or sizes of the shafts.