Abstract:
A coupling arrangement for coupling a traction sheave on a motor shaft includes a taper lock bushing and a traction sheave having a tapered bore adapted to receive the taper lock bushing. The taper lock bushing is sized to slidingly engage with the motor shaft and to fit into the tapered bore of the traction sheave. The taper lock bushing is fastened onto the traction sheave via threaded fasteners to result in a compression fit between the taper lock bushing and the motor shaft.

Description:
RELATED APPLICATIONS 
   This application is a continuation-in-part of U.S. patent application Ser. No. 10/766,310, entitled “Tapered Coupler For Coupling A Motor To A Hoist Machine,” filed Jan. 27, 2004, now U.S. Pat. No. 7,243,759 which is a continuation-in-part of U.S. patent application Ser. No. 10/463,913 entitled “Coupling Arrangement for Coupling A Motor to a Hoist Machine”, filed Jun. 17, 2003, now U.S. Pat. No. 6,681,898, which is a continuation of U.S. patent application Ser. No. 09/974,466 entitled “Adapter Plate For Mounting A Motor Housing To A Hoist Machine Housing,” filed Oct. 10, 2001, now U.S. Pat. No. 6,578,674, which is a divisional of U.S. patent application Ser. No. 09/490,084 entitled “Converter For A Modular Motor To Couple To A Hoist Machine,” filed Jan. 24, 2000, now U.S. Pat. No. 6,315,080, the entire disclosures of all of which are hereby incorporated by reference as if being set forth in their entireties herein. 

   FIELD OF THE INVENTION 
   The present invention relates generally to electric motors and more particularly to a coupling arrangement for coupling a sheave to an electric motor. 
   BACKGROUND OF THE INVENTION 
   Gearless traction elevators driven by electric motors are known in the art. Such elevators are powered by lower speed electric motors, compared to geared traction elevators. In a gearless traction elevator, a traction sheave is directly coupled with a shaft which is rotated by the electric motor. The traction sheave drives one or more cables or ropes which are connected on one end to the elevator and on the other end to a counterweight. 
   In one known method of coupling a traction sheave to a motor shaft, the traction sheave is rigidly fitted and aligned on the motor shaft via a key on the rotating shaft. The traction sheave may rattle about the motor shaft and result in noisy operation. The motor shaft may also be prematurely damaged because of an improper fit between the traction sheave and the motor shaft and may result in hardening of the exterior of the shaft, thereby making it brittle. 
   In view of the above, it is desirable to obtain a coupling arrangement for mounting such a traction sheave directly onto a shaft of an electric motor which enables a proper fit between the sheave and the motor shaft, reduces the possibility of damage to the motor shaft, and is less cumbersome. 
   SUMMARY OF THE INVENTION 
   A coupling arrangement for coupling a traction sheave to a motor shaft, the coupling arrangement including a taper lock bushing. The tapered bushing has a bore adapted to receive the motor shaft. The coupling arrangement also includes a traction sheave which has a tapered bore. The tapered bore is adapted to receive the taper lock bushing. A plurality of fasteners connects the tapered bushing to the traction sheave. 

   
     BRIEF DESCRIPTION OF THE FIGURES 
     Understanding of the present invention will be facilitated by consideration of the following detailed description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings, in which like numerals refer to like parts and in which: 
       FIG. 1  illustrates the top view of an embodiment of a sheave of the present invention; 
       FIG. 2  illustrates the side view of an embodiment of a taper lock bushing of the present invention; 
       FIG. 3  illustrates the cross-sectional view of an embodiment of the sheave of  FIG. 1 , along lines  3 - 3 ; and 
       FIG. 4  illustrates the coupling of an embodiment of a sheave onto a motor shaft. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   It is to be understood that the figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a clear understanding of the present invention, while eliminating, for purposes of clarity, many other elements found in typical methods and systems for coupling an electric motor to a hoist machine. However, because such elements are well known in the art, and because they do not facilitate a better understanding of the present invention, a discussion of such elements is not provided herein. The disclosure herein is directed to all such variations and modifications known to those skilled in the art. 
   Referring now to  FIG. 1 , a traction sheave  100  is illustrated. At the center of the sheave  100 , is a bore  110 . In an embodiment of the present invention, a cross-sectional view of which is illustrated in  FIG. 3 , the bore  110  is adapted to accommodate a motor shaft and a taper lock bushing. The traction sheave  100  has multiple holes  120  adapted to receive bolts or other fasteners. The illustrated holes  120  are radially positioned. The holes  120  may be threaded or non-threaded. The holes  120  may be through holes or may be tap holes. The traction sheave  100  has multiple grooves  130  on its periphery adapted to receive cables or ropes. The grooves  130  are profiled to receive elevator cables or ropes of standards sizes, as are known in the art. 
   Now referring to  FIG. 2 , a taper lock bushing  200  is shown. Such taper lock bushings are known in the art. The taper lock bushing  200  has a flange-like member  210  and a tapered structure  220 . A bore  230  is defined in the flange-like member  210  and the tapered structure  220 . The bore  230  is adapted to receive a motor shaft. The tapered structure  220  is adapted to fit into the bore  110  of the sheave  100 . The length of the tapered structure  220  L is generally equal to the width W of the traction sheave  100 . Multiple through holes  240  are defined in the flange-like member  210 . The holes  240  are adapted to receive fasteners such as a bolt  150 . The holes  240  are positioned so as to align with the holes  120  in the traction sheave  100 . 
   Referring now to  FIG. 4 , an exemplary method of coupling a traction sheave with a motor shaft, according to the present invention will be described. A motor  50  has a motor shaft  52 . A traction sheave  100  is to be coupled to the motor shaft  52  with the help of a taper lock bushing  200 . The tractions sheave has a proximal surface  101  and a distal surface  102 . The traction sheave generally defines a bore  110  which generally matches the profile of a motor shaft of a given diameter. The bore  110  is adapted to receive the taper lock bushing  200 . The bore  110  has interior surface  105 . The bore can be so adapted by machining or drilling or other known manufacturing and machining processes. The taper lock bushing  200  has an exterior surface  205  on the tapered structure  220 . The taper lock bushing has bore  230  which has a larger diameter D 1  adjacent to a flange-like member  210  and a smaller diameter D 2  at the opposite end. Similarly, the bore  110  in the traction sheave  100  has a larger diameter D 1  at the surface  101  and a smaller diameter D 2  at the surface  102 . 
   The taper lock bushing  200  is so selected to have a slide fit with the motor shaft  52 . For illustrative purposes only, the slide fit may be 0.003 to 0.005 inches. The traction sheave  100  is mounted on the motor shaft  52 . The taper lock bushing  200  is inserted in the bore  110  of the traction sheave and onto the motor shaft  52 . In the illustrated embodiment of the traction sheave, the traction sheave  100  has a plurality of tap threaded holes on the surface  101 . Fasteners  150  are used to fasten the taper lock bushing to the traction sheave  100 . Fasteners  150  may be set screws or bolts or known fasteners. As the fasteners are tightened, the taper lock bushing is further pushed into the bore  110  of the traction sheave  100 . The interior surface  105  of the bore  110  exerts compressive forces on the exterior surface  205  of the taper lock bushing  200 . These compressive forces transform the initial slide fit between the taper lock bushing  200  and the motor shaft  52  into a compression fit. 
   If the motor shaft  52  has a tapered profile, the shaft can be machined to a straight profile to couple a traction sheave with the motor shaft using a taper lock bushing. 
   An aspect of the present invention includes a method for retrofitting an existing traction sheave mounted on a motor shaft. Generally, the motor shaft  52  may have a key  410  to align and mount a traction sheave  100  on the motor shaft. The traction sheave  100  is removed from the motor shaft  52 . The bore  110 , which is generally circular is machined to have a tapered profile, as shown in  FIGS. 3 and 4 . The bore  110  is adapted to receive a taper lock bushing  200  by machining or drilling or using other known manufacturing techniques. The traction sheave  100  is then mounted on the motor shaft  52 . The taper lock bushing  200  is also mounted on the motor shaft  52  such that it fits into the bore  110  of the traction sheave. Fasteners  150  are used to fasten the taper lock bushing to the traction sheave  100 . Fasteners  150  may be set screws or bolts or known fasteners. As the fasteners are tightened, the taper lock bushing is further pushed into the bore  110  of the traction sheave  100 . The interior surface  105  of the bore  110  exerts compressive forces on the exterior surface  205  of the taper lock bushing  200 . These compressive forces transform the initial slide fit between the taper lock bushing  200  and the motor shaft  52  into a compression fit. 
   If the motor shaft  52  has a tapered profile, at least a portion of the shaft  52  is straightened up by known machining techniques. The traction sheave  100  having a tapered bore  110  is then mounted onto the straightened portion of the shaft  52 . The taper lock bushing  200  is mounted on the motor shaft  52 , into the tapered bore  110  of the traction sheave  100 . Fasteners  150  are used to fasten the taper lock bushing to the traction sheave  100 . As the fasteners are tightened, the taper lock bushing is further pushed into the bore  110  of the traction sheave  100 . The interior surface  105  of the bore  110  exerts compressive forces on the exterior surface  205  of the taper lock bushing  200 . These compressive forces transform the initial slide fit between the taper lock bushing  200  and the motor shaft  52  into a compression fit. 
   It will be apparent to those skilled in the art that modifications and variations may be made in the apparatus and process of the present invention without departing from the spirit or scope of the invention. It is intended that the present invention cover the modification and variations of this invention provided they come within the scope of the appended claims and their equivalents.