Abstract:
Several embodiments of terminations for flat flexible tension members include wedge type terminations, pinching terminations, and frictional terminations and combinations of the above.

Description:
TECHNICAL FIELD 
     The present invention relates to elevator systems. More particularly, the invention relates to various embodiments for terminating a flexible flat tension member. 
     BACKGROUND OF THE INVENTION 
     A conventional traction elevator system includes a car, a counterweight, two or more tension members interconnecting the car and counterweights; terminations for each end of the tension members at the connection points with the car and counterweights, a traction sheave to move the tension members and a machine to rotate the traction sheave. A second type of conventional elevator roping system is known to the art as a 2-to-1roping system where the rope is terminated to a dead hitch and not the counterweight and car. The tension members have traditionally been formed of laid or twisted steel wire which are easily and reliably terminated by means such as a compression terminations and potted terminations. 
     Compression-type terminations for steel tension members of larger diameters (conventional steel elevator tension members) are extremely effective and reliable. The range of pressures placed on such terminations is reasonably broad without adverse consequence. Providing that the pressure applied is somewhere reasonably above the threshold pressure for retaining the tension members, the termination is effective. 
     Clamp-type and existing wedge-type and termination devices have been employed for flexible flat tension members and are adept at providing reliable terminations. They do however generally require a large amount of overhead clearance space. Since space is always at a premium, it is desirable to provide a termination device which requires less overhead clearance. 
     SUMMARY OF THE INVENTION 
     The above-identified drawbacks of the prior art are overcome or alleviated by the termination device of the invention. 
     A tension member is terminated horizontally to reduce required clearance for the termination device. As one of skill in the art is aware elevator regulations continually reduce clearance areas such as overhead room to conserve building space. The art will be benefited by this invention which in one embodiment, provides a horizontally disposed socket into which a wedge is placed to terminate a tension member. Other embodiments include horizontally oriented lever type arrangements that minimize overhead space. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring now to the drawings wherein like elements are numbered alike in the several FIGURES: 
     FIG. 1A is a perspective view of a one-to-one elevator system; 
     FIG. 1B is a perspective view of a two-to-one elevator system; 
     FIG. 2 is a chematic cross section view of an embodiment of the invention; 
     FIG. 3 is a cross section view of the embodiment of FIG. 2 taken along section line  3 — 3  in FIG.  2 . 
     FIG. 4 is a schematic side elevation view of a second embodiment of the invention which employs leverage to apply a compressive force on a tension member; 
     FIG. 5 is a schematic side view of a fifth embodiment similar to the embodiment of FIG. 4 but providing further and enhanced compressive area; 
     FIG. 6 is another schematic side view of a forth embodiment of the invention where friction in the device prior to the leverage point is enhanced; 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIG. 1A, the relative location of the tension member termination device of the invention can be ascertained. For clarity, an elevator system  12  is illustrated having car  14 , a counterweight  16 , a traction drive  18  and a machine  20 . The traction drive  18  includes a tension member  22  interconnecting car  14  and counterweight  16  which member is driven by sheave  24 . In an alternate configuration, referring to FIG. 1B a two-to-one roping system is illustrated. The general components of such system are a car  15  and counterweight  17  which are interconnected by tension member  22  through idlers  21  and traction sheaves  19 . Such systems are generally compensated by compensation line  25  and sheave  23 . The tension member of this configuration is connected to dead end hitches at  29 . Both ends of tension member  22 , i.e., a car end  26  and a counterweight end  28  or, in a 2-to-1 roping embodiment, the two dead end hitches  29  must be terminated. It is either of these termination points for a flexible flat tension member with which the invention is concerned. An exemplary tension member of the type contemplated in this application is discussed in further detail in U.S. Ser. No. 09/031,108 filed Feb. 26, 1998 entitled Tension Member For An Elevator and U.S. Ser. No. 09/218,990 also entitled Tension Member For An Elevator and filed Dec. 22, 1998, both of which are entirely incorporated herein by reference. The elevator system depicted, is provided for exemplary purposes to illustrate the location of the device of the invention. 
     Referring to FIGS. 2 and 3, a horizontally oriented termination device is illustrated. It will be appreciated that the device is not limited to horizontal but may be disposed at any angle desired through adjustment of certain portions thereof as discussed hereunder. In the horizontally disposed configuration (shown), a socket  90  is preferably of a complex shape having first and second walls  92 ,  94  which follow a contour of a wedge  96  to be placed therein and side walls  98 ,  100  which are substantially parallel to one another and spaced appropriately to allow insertion of wedge  96  therebetween. At a hitch area  102  the first wall  92 , second wall  94  and both side walls  98  and  100  preferably bend downwardly to an opening  104  in termination device  106 . Tension member  22  extends into the device, on the right side and the top section (in the drawing), that is the load side of the device  106 . It is preferred that the tension member  22  be configured in this way because this enables the elevator car load to provide an extra measure of holding strength by compressively loading its own end. It will be appreciated that the loaded side of this device is subject to the force exerted by a hanging elevator car or counterweight. It will be appreciated that the lower portion  108  of FIG. 2 which is a part of section  102 , is longer than its upper counterpart  110 . Portion  108  is longer because it allows the load on tension member  22  to place a compressive force on cut end  112  of tension member  22  against portion  108 . This provides significant friction and will prevent tension member  22  from pulling through device  106  even if for some unlikely reason the wedge  96  becomes unintentionally unseated from socket  90 . It should also be noted that even if tension member  22  is threaded into device  106  in the opposite direction, the friction provided by portion  108  yields more holding force than prior art terminations. 
     Termination device  106  is maintained in the desired position when under load by positioning pin hole bracket  114  in a specific position. Pin hole bracket  114  should be positioned to be centered over the direction of the load on tension member  22 . By orienting the device relative to this centering, the attitude of the device will remain stable. It is preferable for the angle of the device relative to the direction of the load to be about 90 degrees to a vertical reference to minimize the height of the termination. 
     With respect to disassembly of device  106 , wedge  96  is provided with through hole  116 . As can be appreciated in FIG. 2, hole  116  is disposed within wedge  96  in a position to allow hole  116  to be about one-half exposed from socket  90  when the wedge  96  is in the fully engaged (loaded) position. Hole  116  provides a means of extracting wedge  96  from socket  90  by accepting a separate tapered rod (not shown) which can be tapped into hole  116 . The rod will bear on a back surface  118  of socket  90  and urge wedge  96  out of socket  90 . 
     Referring now to FIG. 4 another termination device of the invention is illustrated. This embodiment applies compressive force to the tension member  22  through a leverage arrangement. Leverage is created, by lower lever  140  through fulcrum  142  to upper level  144 . It is to be understood the terms “lower” end and “upper” are relative and could be reversed without changing the friction of the device. 
     Lower lever  140  preferably provides a top friction surface  146  having a radiused load end  148  which radius is preferably selected to meet minimum bend radius requirements for a flat tension member. A pin  150  is provided for fulcrum  142 . Preferably sufficient room is provided between a pair of arms  152  extending from lever  144  to receive lever  140  and tension member  22 . Arms  152  are also preferably long enough to provide minimally enough space between surface  146  of lever  140  and a lower surface  154  of lever  144  to allow tension member  22  to be invested therebetween. It should also be noted that lever  144  is preferably longer than lever  140  in order to provide material in which pin hole  156  may be bored and be centered above a load direction of tension member  22 . 
     In another embodiment of the invention, referring to FIG. 5, the basic concept remains the same but compressive force generated by the device is enhanced due to the location of the generation of such force. The embodiment includes a lower level  162  having a friction surface  164  with a radius  166  on one edge thereof and an angled surface  168  on another edge thereof. A pivot pin  170  is located in a preselected position relative to the length of lower level  162 . The appropriate placement of pin  170  is determined by calculation and is discussed further hereunder. An upper lever  172  is preferably longer than lever  162  on one end thereof to provide material through which pin hole  174  is provided. On an opposite end of lever  172  from pin hole  174  is angled section  176  which is provided with an angled contact surface  178 . Contact surface  178  is preferably about parallel with angled surface  168  when the upper and lower levers  162 ,  172  are in a parallel relationship to one another. Arms  180  (only one visible) are preferably long enough to space lever  172  from lever  162  by an amount sufficient to ensure that compression of the rope occurs between surface  168  and  178  and not between the horizontal surfaces. 
     In the embodiment, the tension member  22  is threaded through from right to left in the drawing. The load (elevator car not shown) placed on tension member  22  causes the termination device to act by pulling the right side of lever  162  downwardly making the left side of lever  162  impinge on surface  178  of lever  172 . The clamping or compressive force on the tension member between surfaces  168  and  178  is dictated by:        FN   =     F                   R     (       S   ·   sin                   α     )                                
     Where 
     F is the load on tension member  22 ; 
     R is the distance between a center of load F and pivot point  170 ; 
     S is the distance between pivot point  170  and the desired location of clamping force FN, as shown in FIG. 12; 
     α is the angle between a line normal to lever  172  and surface  178 . 
     Mechanical advantage is increased in this embodiment as can be illustrated by an example. Where the latter embodiment would create a mechanical advantage of 3, the angular surfaces of this embodiment where the angle α=20 degrees provide a mechanical advantage of 8.8. A significant enhancement is therefore realized in this embodiment without adding significant complexity to the device. 
     In yet another similar embodiment of the invention, referring to FIG. 6, the termination device  190  is made shorter than its two proceeding cousins by adding frictional forces through curved contact surfaces. The device does not experience higher loading on the pivot than the embodiments of FIGS. 4 and 5. In this embodiment an upper lever  192  provides a sinuous contact surface  194  on its lower surface which approximates a sinuous contact surface  196  on lower lever  198 . The sinuous surfaces provide enhanced frictional characteristics and thus remove additional tensile stress from tension member  22 . By so removing the leverage on a pivot pin  200  in lower lever  198  is not made higher by a shorter overall length of device  190 . A pin hole  202  is provided in upper lever  192  to secure device  190  to a dead end hitch (not shown). 
     Although the invention has been shown and described with respect to exemplary embodiments thereof, it should be understood by those skilled in the art that various changes, omissions, and additions may be made thereto, without departing from the spirit and scope of the invention.