Abstract:
A shaft such as a worm drive shaft for a movable barrier operator is disclosed. The shaft includes at least two shaft segments having connection ends. The shaft segments include respective connection ends permitting a first connection end to be joined with a second connection end by inserting a portion of at least one of the connection ends within the other connection end along the longitudinal axis of the shaft. The shaft segments may be retained by a resiliently expandable connector such as a snap ring. The connector may expand to permit the joining and then contract to be received within a surface recess on a connection end. The connector may be part of or pre-assembled on a connection end, such as by being positioned within a surface recess thereof. The connector may provide a pre-determined position for joining the first and second connection ends.

Description:
FIELD OF THE INVENTION 
     The invention relates to a connection between elongated members and, in particular, to a connection between sections or segments of a drive shaft for a movable barrier operator. 
     BACKGROUND OF THE INVENTION 
     Many residential garages are equipped with an operator for providing electromechanical movement of the garage door between an open position and a closed position. Various systems have been devised for attaching the operator to the garage door to effect such movement. These systems may include a cable, a belt, or a threaded shaft commonly referred to as a worm shaft. 
     For many residential owners, the installation of a garage door seems a relatively easy, do-it-yourself task. Instruction manuals are presented with detailed pictures and precautions to guide people through the steps, necessitating equipment as common as a screwdriver and a power drill. Before beginning installation, however, the would-be installer must first acquire or purchase the system and transport it to the installation site. 
     One of the issues presented with transporting the operator system to the installation site is the size of the system. When the movable barrier or door is in an open position, most garages provide an opening roughly equivalent to what one would expect from a standard door frame, approximately eighty inches. A typical garage door will, in the closed position, rest on a ground surface such as a garage floor and generally span the garage door opening. To open the garage by moving the door to the open position, requires the door to shift from contact with the ground surface to a position sufficient to allow passage for cars or people or other items through the garage opening. That is, the door will travel approximately eighty inches between the open and closed position. For taller garage openings equipped with larger doors, it may be desired for the door to travel a distance greater than eighty inches. 
     For operator systems utilizing a worm shaft, the distance the door must travel determines, to some extent, the length of the worm shaft that must be transported to an installation site. That is, the shaft must be of sufficient length to provide for the described amount of travel. Though some people have uncommonly large automobiles or other vehicles that may provide for a shaft having an eight-foot length, many people find it cumbersome and difficult to load such an item into their car. Additionally, the operator system is desirably packaged and sold in a single carton, inside of which includes a generally rectangular operator box including a motor and a connection for the worm shaft, the worm shaft itself along with a supporting rail, and hardware components for coupling the rail and shaft with the garage door and for mounting the operator box in the garage, such as to a ceiling or rafter support. Were the rail and shaft a single component of eighty or more inches, and this were packaged in a single carton with a relatively heavy operator box, the entire carton can prove unwieldy for many people. 
     In order to address this problem, there are a number of currently known approaches for providing a worm shaft having a plurality of shorter segments which are coupled together. In this manner, the operator system may be packaged in a smaller and easier-handled carton. A user or installer may then assemble the segments into the full-length worm shaft prior to installation. 
     One example of an segmented shaft is described in U.S. Pat. Nos. 4,352,585, and 5,085,094. To form a connection or joint between first and second shaft segments, cooperating structure is provided on the ends of the shafts. More particularly, each joint end is generally cylindrical and includes a first cut section at a first depth to form a surface parallel to the longitudinal axis of the shaft, and a second cut section at a second depth greater than and parallel to the first depth. The second cut section is made further away from a shaft terminus so that it forms a notch in the cylindrical end. Respective notches in the first and second shaft segments are joined so that the first cut section of the first segment is mated with the second cut section of the second segment, and the second cut section of the first segment is mated with the first cut section of the second segment. In this manner, the mated end portions including the cut sections together form a cylindrical outer surface. 
     The end portions must be maintained in the mated relationship. To accomplish this, a full ring piece is positioned around the cylindrical portion of one of the segments so that it is clear of that segment&#39;s notch prior to mating with the other segment. Once mated, the ring is slid over the notches to hold the segments together. Lastly, a partial ring is snapped onto the portion from where the ring is slid to prevent the full ring from backing away from the joint. 
     With the described notched-connection utilizing the rings, a number of components and steps are required for assembly. Users or installers are required to first slide on the full ring as a separate component, then couple the notches, slide the ring over the joint, then snap on the separate component of the partial ring. This requires a user to keep track of small components and to manipulate the small components in conjunction with the large shaft segments. 
     Accordingly, there has been a need for a simpler and more user-friendly assembly and joint for a shaft for a movable barrier operator system. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect, an elongated drive shaft such as a worm shaft for use with a movable barrier operator is disclosed. The elongated shaft has worm threads and is rotated around its central longitudinal axis by a motor. A trolley is engaged with the threads so that rotation of the shaft effects translation of the trolley along a support rail in which the shaft is located. 
     The shaft includes at least two segments that are joined to ease the shipping, packaging, transportation, and assembly by a user or installer. The trolley has engagement portions such as teeth that extend a length sufficient to maintain engagement with the threads as the trolley passes over or travels by the joint. 
     The joint is provided as a simple connection. In particular, first and second connection ends are provided on respective shaft segments. The connection ends include male and female connections such that the first connection end is joined with the second connection with a single linear motion. 
     Once joined, a connector prevents separation of the connection ends. As one of the connection ends is advanced towards the other connection end, the connector expands or shifts to permit the advancement and joining of the connection ends. After the connection ends are joined at a predetermined position, the connector contracts to couple with the advancing connection end. In one form, the connector is a separate component pre-assembled with one of the connection ends, and the other connection end forces the expansion or shifting of the connector during relative advancement of the connection ends. In a preferred embodiment, the connector is a split ring pre-assembled in a recess on a first connection end, and the second connection end is received within the split ring to shift the split ring to an expanded configuration. Once the connection ends are sufficiently advanced relatively, the split ring becomes aligned with a recess on the second connection, thereby contracting to shift into the second connection end recess. 
     In accordance with one aspect, a method of forming an elongated drive shaft for a movable barrier operator system for moving a movable barrier between positions is provided. The method includes providing a first shaft segment having a longitudinal axis of rotation and a first connection end; providing a second shaft segment having a longitudinal axis of rotation and a second connection end; aligning the shaft segments along a common axis of rotation; and joining the first and second connection ends by forcing a cooperating structure of each connection end to be received by cooperating structure on the other connection end. The method may further include providing an expandable portion on the cooperating structure of one of the first connection end, wherein the joining of the first connection end and second connection ends includes forcing the cooperating structure of the second connection end against the expandable portion of the first connection end to expand the expandable portion. Even further, the method may include aligning a portion of the cooperating structure on the second connection end with the expandable portion and with a portion of the cooperating structure of the first connection end; and contracting the expandable portion into the aligned second connection end. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings,  FIG. 1  is an exploded and fragmentary perspective view of components of a shaft for forming a joint including a first drive shaft segment, a second drive shaft segment, and a connector ring; 
         FIG. 2  is a perspective view of a representational interior of a garage showing a movable barrier operator system for shifting a movable barrier between open and closed positions; 
         FIG. 3  is a cross-sectional view of a portion of the movable barrier operator system including an operator trolley operably connectable to the movable barrier, a support rail for attaching to an interior of the garage, and a drive shaft rotatably supported by the support rail for translating the operator trolley for shifting the movable barrier between the open and closed positions; 
         FIG. 4  is a fragmentary view of the support rail showing a joint between the drive shaft segments and the trolley positioned across the joint; 
         FIG. 5  is a fragmentary side elevational view of the first drive shaft segment showing a first connection end; 
         FIG. 6  is a fragmentary side elevational view of the first connection end of the first drive shaft segment rotated ninety degrees from  FIG. 5 ; 
         FIG. 7  is an end elevational of the first connection end of the first drive shaft segment; 
         FIG. 8  is a fragmentary side elevational view of the second drive shaft segment showing a second connection end; 
         FIG. 9  is a fragmentary side elevational view of the second connection end of the second drive shaft segment rotated ninety degrees from  FIG. 8 ; 
         FIG. 10  is an end elevational of the second connection end of the second drive shaft segment; 
         FIG. 11  is a fragmentary perspective view of the joint in an assembled configuration; and 
         FIG. 12  is a fragmentary cross-sectional view of the joint of  FIG. 11 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring initially to  FIGS. 1 and 2 , a rotating shaft  10  for use with a operator system  12  for moving a movable barrier  22  between positions defining open and closed positions for a garage  20  is depicted. The rotating shaft  10  forms a connection joint  14  between first and second shaft segments  16 ,  18 . The garage  20  includes an opening  24  generally bound by a ground or floor surface  26 , side walls  28 , and a top wall  30 .  FIG. 2  illustrates the garage  20  with the barrier  22  in a closed position such that the opening  24  is generally spanned by the barrier  22 . The operator system  12  is used to raise the barrier  22  from the closed position to an open position to allow ingress and egress of persons, vehicles, or the like, through the opening  24 . 
     The barrier  22  is guided between the open and closed positions by rails or tracks  38  mounted to the side walls  28 . The barrier has sides  40  which include axle and wheel assemblies  42 . The wheel assemblies  42  are positioned within the tracks  38 . In order to move from the open and closed position, the barrier  22  must move an appropriate distance for desired opening. That is, though the opening  24  has a particular height H, the barrier  22  may move to expose to opening more or less than the height H. For instance, it may be only necessary for the barrier  22  to move to the open position so there is a clearance below a bottom edge  44  of the barrier  22  that is some amount less than the height H. However, actual distance traveled by the bottom edge  44  of the barrier  22  may be different than the clearance amount as the tracks  38  have a curved upper portion  46 . The shaft  10  must provide a length that permits the distance traveled by the bottom edge  44  of the barrier  22  between the open and closed positions. 
     The operator system  12  includes an operator or drive box  60  providing power for moving the barrier  22 . The drive box  60  includes an electrical motor (not shown) for providing rotation power to a socket connection formed by a connection end  62  of the shaft  10  (see  FIG. 4 ) and a connection (not shown) extending from the motor through a housing  64  of the drive box  60 . As can be seen in  FIG. 3 , the shaft  10  is rotatably supported within a shaft rail  70 . The shaft rail  70  preferably includes a bushing sleeve  72 , such as a low-friction polymeric sleeve such as Nylon or Delrin. The bushing sleeve  72  is partially cylindrical so that a longitudinally extending portion is removed, and the sleeve  72  has a C-shape with an opening  74  oriented downward when installed. The shaft rail  70  supports the sleeve  72  within a C-shaped portion  76  with an opening  80  co-oriented downwardly with the sleeve opening  74 . Therefore, the shaft  10  is exposed from the shaft rail  70  when installed within the sleeve  72 . 
     The shaft  10  cooperates with a trolley  90  through the openings  74 , 80  in the sleeve  72  and shaft rail  70 . As can be seen in  FIG. 5 , the shaft  10  has outwardly extending threads  92  substantially along its length. The trolley  90  includes cooperating structure such as a plurality of pitched teeth  94  which are shaped to cooperate with the shaft threads  92  so as to draw the trolley  90  along the shaft  10  when the shaft  10  rotates around its own axis. The pitch of the teeth  94  is selected according to the pitch of the threads  92  of the shaft  10 , which are in turn selected based on how many rotations are used to shift the barrier  22  a particular distance, which is itself a function of power delivery from the motor. 
     The trolley  90  is supported by the shaft rail  70 . The shaft rail  70  includes guide slots  100  extending laterally to the direction of travel of the trolley  90 , which is parallel to the axis of rotation of the shaft  10 . The trolley  90  includes laterally extending wings or flanges  102  received within the slots  100 . As the trolley  90  travels along the shaft rail  70  when the barrier  22  is being moved between or to the open and closed positions, the flanges  102  slide within the slots  100 . 
     To move the barrier  22 , the motor rotates the shaft  10  such that the trolley  90  translates along the shaft rail  70 . The trolley  90  is connected to the barrier  22  by a bracket  110 . The bracket  110  is pivotally connected to both the barrier  22  and the trolley  90 . This is due to the fact that, from a closed position, the initial direction of travel for the barrier  22  is in a vertical motion, the travel then transitions through the curved upper portion  46  of the tracks  38 , and then finally becomes a generally horizontal direction of motion. In contrast, the trolley  90  generally only moves in a horizontal direction along the shaft rail  70 . The bracket  110 , thus, pivots to allow the trolley  90  and barrier  22  to move as described. 
     The shaft  10  has a requisite length. The length of the shaft  10  includes the extent of travel required by the trolley  90  to move the barrier  22  between the open and closed positions. As can be seen in  FIG. 4 , the trolley  90  itself has a particular length for spanning across the connection joint  14 . The shaft  10  has the connection end  62  cooperating with the drive box  60 , and the extent of travel by the trolley  90  preferably stops short of the drive box  60 . The shaft  10  also has a dead end  112 , permitted to freely rotate within the rail  70 , opposite the connection end  62 . It is also preferred that the extent of travel by the trolley  90  stops short of the dead end  112 . 
     The operator system  12  is shipped and provided in a disassembled state so that it is easy to transport, handle, and manipulate. In particular, the shaft  10  is provided in segments, such as the first and second segments  16 ,  18 , to facilitate the same. The segments  16 ,  18  are coupled by a user or installer at the installation site. It should be noted that the shaft  10 , as described, includes the two segments  16 ,  18 , though a greater number may be provided, each segment being connectable with another such as by the connection joint  14 , as will be described. 
     Referring now to FIGS.  1  and  5 - 12 , the first shaft segment  16  is shown having a male connection end  120 , the second shaft segment is shown having a female connection end  140 , and a connector  160  is shown as a split ring. The split ring  160  is positioned around the male end  120 , preferably by the manufacturer prior to the operator system  12  being shipped. The female end  140  is inserted into the male end  120  and the split ring  160  to connect the shaft segments  16 ,  18 . 
     The male connection end  120  is illustrated in FIGS.  1  and  5 - 7 . The male end  120  is generally cylindrical with a dimension less than the threads  92 , or at least less than a depth into which the trolley teeth  94  are received in the threads  92 . Accordingly, the teeth  94  are able to travel by or over the joint  14  without interference. 
     The male end  120  includes diametrically aligned recesses  122  for receiving the female connection end  140 . The first shaft segment  16  has a terminal end  124  including an entrance  126  for each of the recesses  122 . Each recess  122  is defined by a opposed side wall  128  and a bottom wall  130 , which is preferably orthogonal to the opposed side walls  128 . The bottom walls  130  at the entrance  126  have a generally planar portions  132  which are parallel. As the bottom wall  130  extends away from the terminal end  124 , it transitions into a sloped portion  134 , which slopes outwardly from the planar portion  132  and from the longitudinal axis of the segment  16 , as can be seen in  FIGS. 1 ,  5  and  12 . 
     A short distance from the terminal end  124  is a groove  136  for receiving the split ring  160 . The split ring  160  includes a slit or gap  162  so that the split ring  160  may expand slightly to be positioned around the segment  16  and, in particular, in the groove  136 , and then contract to a tight fit within the groove  136 . The split ring  160  and groove  136  are sized so that, once the split ring  160  is positioned within the groove  136 , the diametrical size therealong is at least less than the depth into which the trolley teeth  94  are received in the threads  92  so that the teeth  94  are able to travel over the split ring  160  without interference. The terminal end  124  of the segment  16  forms a generally flat face  138  and on a radial plane orthogonal to the longitudinal axis. 
     The female connection end  140  is illustrated in FIGS.  1  and  8 - 10 . The female connection end  140 , like the male connection end  120 , is generally cylindrical with a dimension at least less than the depth into which the trolley teeth  94  are received in the threads  92  so that the teeth  94  are able to travel by the joint  14  without interference. 
     As can be seen in  FIG. 9 , the female end  140  includes a pair of oppositely positioned cutouts  142  that are generally parallel to each other and to the longitudinal axis of the shaft  10 . Each cutout  142  extends a distance from a terminal end  144  of the segment  18  to a shoulder  146  radially extending from and orthogonal to the shaft segment longitudinal axis. 
     With the cutouts  142 , the female end  140  includes opposed connection prongs  148  for mating with the male connection end  120 . A cutout or recess  150  is formed between the prongs  148 . Each prong  148  has an end face  151  at the terminal end  144  that includes an inner edge  152  that is preferably rounded or the like. As the female end  140  is connected to the male end  120 , the male end recess bottom walls  130  are received between the prongs  148  and in the recess  150 . The inner edge  152  forms a chamber or wedge to promote reception of the prongs  148  in the male end recesses  122 . 
     Each prong  148  includes a chamber or bevel  154  leading from the end face  151  and extending outwardly therefrom, as can be seen in  FIGS. 8 and 12 . As the female end  140  is brought into engagement with the male end  120 , the bevels  154  contact a leading edge  164  and/or inner surface  166  of the split ring  160  to force expansion of the split ring  160 . A short distance from the bevel  154  and along the outer surface of the prong  148  is a recess  156  having a general shape to match the split ring  160  and the groove  136  of the male end  120 . When the female connection end  140  has been received the proper amount in the male end  120 , the prong recess  156  is aligned with the male end groove  136 . The split ring  160  is then able to contract so that it is received in both the prong recesses  156  and in the male end groove  136 . 
     The connection joint  14  formed by inserting the female connection end  140  within the male connection end  120  and the split ring  160  is substantially rigid. That is, at the proper insertion depth for the female connection end  140 , the split ring  160  is received within the prong recesses  156  and male end groove  136  so that excess space, or play, is minimized. In other words, the prong recesses  156  and the male end groove  136  are preferably configured to closely match in diametrical geometry and axial length so that the split ring  160  fits closely within each simultaneously. 
     The mating between the female and male ends  140 ,  120  further promotes the rigidity of the connection joint  14 . The sidewalls  128  of the male end recesses  122  are configured to closely match against the prongs  148  within the cutouts  142 , which serves to guide the prongs  148  therewithin. The recess  150  between the prongs  148  is closely sized and shaped for the male end  120  between its bottom walls  130 , also serving to guide the connection. These features limit the axial deviation of the first segment  16  from the second segment  18 . Though not shown as such, the female and male ends  140 ,  120  may be connected to a depth such that a terminal face  158  of the female end recess  150  may abut flushly with the face  138  on the male terminal end  124 . Alternatively, the female end shoulder  146  may contact flushly against the male terminal end face  138 . As a further alternative, the female end recess  150  may be cut to a depth coincident or co-planar with the female end shoulder  146  so that both its terminal face  158  and the female end shoulder  146  abut the male terminal end face  138 . 
     For a user, assembling the joint  14  for the shaft  10  including the first and segments  16 ,  18  having the male and female connection ends  120 ,  140  is simplified. The split ring  160  may be pre-assembled with the male connection end  120  so that the user merely handles the first and second segments  16 ,  18 . The user may grasp the segments  16 ,  18 , align the prongs  148  with the recess entrances  126 , and connect the segments  16 ,  18  with a single, linear motion. The male and female connection ends  120 ,  140  are self-securing as the split ring  160  will expand as necessary and then contract when the female end  140  is inserted to the proper depth. The joint  14  is thus formed. 
     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.