Patent Publication Number: US-6659231-B2

Title: Self-balancing synchronization assembly for a hydraulic elevator

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to hydraulic elevators and, in particular, to a self-balancing synchronization assembly for a jack in a hydraulic elevator. 
     Hydraulic elevator systems are well known. Such systems include an elevator car movable along guide rails within a hoistway, and a jack with at least one telescoping piston slidably received in a corresponding cylinder supporting and moving the elevator car. A pressurized working fluid, such as oil, is introduced into or removed from the volume between the telescoping piston and the interior of the cylinder in order to reciprocate the piston and move the elevator car vertically within the hoistway. 
     If the hydraulic elevator utilizes two or more telescoping pistons, a synchronizing device must be provided to coordinate movement of the pistons. The Swiss patent publication 463 745 shows an elevator with a hydraulic or pneumatic telescopic ram having two or three pistons. A mechanical connecting means engages between the telescopic parts and in each stroke ensures uniformly distributed part strokes between the successive telescopic parts. Chains or cables deflected over rollers are, in particular, used as the mechanical connecting means. 
     The U.S. Pat. No. 6,098,759 shows another hydraulic elevator construction having a pair of ropes connected at one end to a crossbeam mounted on the guide rails at the top end of the hoistway. The elevator car is supported by a jack of the two-stage type with an intermediate piston and a lower piston telescopically extending from an upper cylinder. The other end of each rope is attached to a sleeve on the cylinder. An intermediate portion of each rope extend below the ends and passes over an associated sheave rotatably mounted on an intermediate piston of the jack thereby changing direction by 180 degrees. 
     The known synchronizing devices have problems such as requiring room at the top of the hoistway for mounting and typically being custom designed to fit the particular hoistway configuration. The multiple synchronization cables require individual adjustment for retensioning either at the hoistway mounting point or at the attachment point on the jack flange. 
     SUMMARY OF THE INVENTION 
     The present invention concerns a self-balancing synchronization assembly for a hydraulic elevator system. The synchronization assembly includes a support beam which mounts via a pivoting pin to an elevator car guide rail, rather than the piston flange as in the prior art. The support beam has first and second ends that extend on either side of the guide rail. On the first end, the beam supports the downward load of at least one pair of synchronization cables. On the second end, a support cable extends downwardly to the elevator pit and attaches to the pit floor via a turnbuckle or similar tensioning device. The corresponding synchronization cables for each piston flange and the support cable mount to a synchronization bracket and support bracket, respectively, each of which is attached to the support beam by a pivoting pin connection. The pivoting connection allows the matching two synchronization cables for each piston flange to equalize loads. The synchronization cables create a resultant downward load on the first end of the pivoting support beam. A load, therefore, is required on the second end of the support beam to balance the synchronization load, which is accomplished by the support cable mounted to the support bracket on the second end of the support beam. The support cable extends to the elevator pit or hoistway floor, which advantageously allows cable tensioning from a single point at the elevator pit floor. 
     The synchronization assembly according to the present invention also eliminates all hoistway wall or overhead attachment interfaces, which permits tensioning of the cables in the hoistway pit, which is easier to access and has more structural strength than connections at the hoistway walls or the piston flanges. 
     In addition, the present invention allows the installation of the same equipment regardless of the building type because the present invention uses a single beam design for all variations of hoistway width and construction type. 
     Furthermore, the present invention can be used to synchronize two-stage and three-stage hydraulic elevators because each pair of synchronization cables is attach to a separate synchronization bracket. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The above, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment when considered in the light of the accompanying drawings in which: 
     FIG. 1 is a partially exploded perspective view of a self-balancing synchronization assembly for an elevator jack in accordance with the present invention; and 
     FIG. 2 is an enlarged fragmentary perspective view of the self-balancing synchronization assembly shown in FIG. 1 attached to an elevator guide rail and having a plurality of cables attached thereto. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A dual-jack type elevator has a separate hydraulic jack positioned adjacent each sidewall of the elevator hoistway for raising and lowering an elevator car. As described above, the jacks can be a two-stage or a three-stage type that requires synchronization of the telescoping parts for smooth elevator operation. The synchronization assembly according to the present invention permits tensioning of all synchronizing cables from a single point in the hoistway pit and can be used in all types of hoistway construction. 
     Referring now to FIG. 1, a self-balancing synchronization assembly is indicated generally at  10 . The synchronization assembly  10  includes an elongated support beam  12  having a first end  14  and a second end  16 . The support beam  12  is pivotably mounted by a pivot pin  17 , or other suitable attachment means, to a pivot plate  18  intermediate the first end  14  and the second end  16 . The pivot plate  18  is adapted to be affixed to a guide rail (FIG. 2) for a hydraulic elevator such that the support beam  12  pivots (as shown by an arrow  19 ) in a generally vertical plane about a pivot point defined by the pivot pin  17 . The support beam  12  preferably is sized to extend across much of the width of an elevator hoistway sidewall. 
     A generally triangular-shaped first synchronization bracket  20  is pivotably attached adjacent to the first end  14  of the support beam  12  by a pin connection  22  or similar pivoting attachment means at an apex of the triangle. The first synchronization bracket  20  includes a generally planar bracket portion  24  and a mounting portion  26  extending generally perpendicularly from a base of the bracket portion  24 . The mounting portion  26  includes a center attachment aperture  28  located below the pin connection  22  and a pair of outer attachment apertures  30  formed therein. Each of the attachment apertures  28  and  30  is adapted to attach to an end of a synchronization cable (FIG. 2) having an opposite end attached to a flange (not shown) of an elevator piston. A first bracket stop  32  extends generally perpendicularly from the support beam  12  between the first end  14  and the pin connection  22  for engaging an edge of the bracket portion  24  to limit the pivoting movement of the first synchronization bracket  20 . 
     A generally triangular-shaped second synchronization bracket  34  is also shown having the same general configuration as the first synchronization bracket  20 , including a bracket portion  36 , a mounting portion  38 , a center attachment aperture  40  and a pair of outer attachment apertures  42 . The second synchronization bracket  34  is pivotably mounted on the pin connection  22  between the first synchronization bracket  20  and the support beam  12 . Each of the attachment apertures  40  and  42  is adapted to attach to an end a synchronization cable (FIG. 2) in a manner similar to the apertures  28  and  30 . 
     A return bracket  44 , generally having the same structure as the synchronization bracket  20 , includes a bracket portion  46 , a mounting portion  48 , a center attachment aperture  50  and a pair of outer attachment apertures  52 . The return bracket  44  is pivotably attached adjacent to the second end  16  of the support beam  12  by a pin connection  54  or similar pivoting attachment means. A bracket stop  56  extends generally perpendicularly from the support beam  12  on the side of the bracket portion  46  opposite the second end  16  for engaging an edge of the return bracket  44  to limit pivoting movement thereof. The bracket  44  can be identical to the bracket  20 . In the alternative, the center aperture  40  and the outer apertures  52  can be eliminated, or the bracket  44  can be fixedly attached to the support beam  12 , or the bracket  44  can be eliminated and the aperture  50  formed in the support beam. 
     An eyebolt  58  is shown mounted in the center attachment aperture  52  extending downwardly and retained by a nut  59  or similar attachment means. An upper end  60  of a return cable  62  is threaded through the eye of the eyebolt  58  and affixed to the cable by a plurality of U-bolts  64  or similar cable termination means. Alternatively, the return cable  62  can be received in one of the apertures  52  and  54  in the return bracket  44  or a similar aperture formed in the support beam  12 . A lower end  66  of the support cable  62  can be attached to an upper end  68  of a turnbuckle  70  near the pit floor (not shown) by a plurality of U-bolts  72  or similar cable termination means of adequate strength and efficiency. A lower end  74  of the turnbuckle  70  attaches to an anchor plate  76 , which in turn mounts directly to the elevator pit floor using a plurality of concrete anchors  78  or similar fasteners. 
     Referring now to FIG. 2, the synchronization assembly  10  is shown with the pivot plate  18  attached to an elevator guide rail  80  by a plurality of fasteners  82 . The synchronization brackets  20  and  34  are pivotally attached to the first end  14  of the support beam  12  extending beyond one side of the guide rail  80 . The return bracket  44  is attached to the second end  16  of the support beam  12  extending beyond the other side of the guide rail  80 . The support eyebolt  58  attaches the cable upper end  60  to the support bracket  44 . 
     Each of a pair of eyebolts  84  and  86  is attached to the first synchronization bracket by fasteners  88  or similar attachment means at the apertures  30 . A pair of synchronization cables  90  and  92  forms a first synchronization cable pair. An upper end of the synchronization cable  90  is retained by the eyebolt  84  and affixed onto itself by a plurality of U-bolts  94  or similar cable termination means. An upper end of the synchronization cable  92  is retained by the eyebolt  86  and affixed onto itself by a plurality of the U-bolts  94  or similar cable termination means. Each of a pair of eyebolts  96  and  98  is attached to the second synchronization bracket  34  by fasteners  100  or similar attachment means. A pair of synchronization cables  102  and  104  forms a second synchronization cable pair. An upper end of the synchronization cable  102  is retained by the eyebolt  96  and affixed onto itself by a plurality of U-bolts  106  or similar cable termination means. An upper end of the synchronization cable  104  is retained by the eyebolt  98  and affixed onto itself by a plurality of the U-bolts  106  or similar cable termination means. 
     The lower ends (not shown) of the synchronization cables attach to one or more flanges of the hydraulic elevator jack in a manner similar to the attachment to the brackets  20  and  34 . For example, when utilized with a two-stage jack, only the cables  90  and  92  need be attached to opposite sides of a jack flange and the cables  102  and  104  as well as the bracket  34  can be eliminated. An alternative is to utilize the cables  102  and  104  and eliminate the cables  90  and  92  and the bracket  20 . When utilized with a three-stage jack, the cables  90  and  92  are attached to opposite sides of one piston flange and the cables  102  and  104  are attached to opposite sides of the other piston flange. For the best elevator ride, the load on the synchronization cables must be nearly equal to provide equal loading between the sides of the jack flanges. The pivot assembly provided by both the brackets  20  and  34  equalizes uneven cable tension between the two cables attached to the bracket through rotation about the pin  22 . 
     The synchronization assembly  10  is installed by mounting the pivot plate  18  to the guide rail  80  and attaching the lower ends of the synchronization cables  90  and  92  (and  102  and  104  if required) to the jack flange. The turnbuckle  70  at the lower end  66  of the return cable  62  is attached to the anchor plate  76  that has been affixed to the bottom of the hoistway pit. The synchronization cables and the return cable are adjusted to balance the load on the ends  14  and  16  of the support beam such that the beam is substantially horizontal. During use, the synchronization cables  90 ,  92 ,  102  and  104  tend to stretch leading to unsynchronization. To retension the synchronization cables, the turnbuckle  70  is turned to decrease the length of the return cable  62  thereby rotating the support beam  12  about the pivot pin  17  to lower the second end  16  of the support beam  12  and increase the downward load. The first end  14  rotates upwardly increasing the upward load on the synchronization cables. Since the brackets  20 ,and  34  rotate about the pin  22 , the pair of cables attached to each bracket automatically balance the load. Thus, it is only necessary to adjust the single return cable  62  in order to retension the entire synchronization assembly  10 . 
     In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiment. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.