Abstract:
An elevator tape guide for a hoistway tape includes a mounting plate having recesses for receiving insertable plug members, the plug members each have two tape engaging slots with the slots being severally registrable with the tape for slot wear-replacement.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to elevator control systems and especially to elevator monitoring apparatus. 
     In particular, the device of this invention concerns an improved tape guide for use with an elevator hoistway tape. 
     2. Background Information 
     Elevator control systems, among other functions, monitor the speed and location of an elevator cab assembly within an elevator hoistway by sensing movement of the cab relative to a stationary tape vertically suspended in the hoistway. The tape is commonly provided with indicia such as a series of apertures, or magnetic elements, or light-reflective vanes. A sensor unit mounted on the elevator cab detects the indicia and generates corresponding output signals that are transmitted to an elevator controller. 
     Tape guides mounted on the elevator cab assembly engage opposite edges of the tape to precisely position the tape with respect to the sensor unit. The tape guides include guide slots for slidingly receiving the respective edges of the tape. The relative displacement of the tape within the guide slots, over a period of time, result in wear changes in the guide slot which effect sensing performance. This can be detected during routine maintenance of the elevator system and corrected by replacement of the tape guides. However, the elevator servicing requires temporarily disabling the elevator cab for the removal and replacement of the tape guides. This can be a time-consuming and costly procedure and an inconvenience to passengers. 
     Several attempts have been made to extend the useful life of tape guides including a tape guide construction having reciprocal tape slots on opposite faces of the guide. The life of the tape guide can be prolonged by removal and remounting for use of the tape slot on the reverse face of the guide. Nevertheless, after the second slot has been used, the entire tape guide must be discarded and replaced. 
     Another tape guide with an alternative slot arrangement is shown in U.S. Pat. No. 4,798,267 and has similar shortcomings. The use of non-abrasive material for reducing friction within a tape guide is disclosed in U.S. Pat. No. 5,925,859. The tape guide arrangement of U.S. Pat. No. 5,360,085 is intended to reduce operating noise, and the tape guide shown in U.S. Pat. No. 4,674,603 is directed to facilitating removal and repair. The aforementioned tape guides do not achieve the maintenance expediency and cost economy of the present invention. 
     BRIEF SUMMARY OF THE INVENTION 
     Briefly, the nature of this invention concerns an elevator tape guide with redundant guide slots. The tape guide includes a mounting plate adapted for attachment to an elevator cab assembly. The mounting plate accommodates a removable plug member. The plug member includes two tape guide slots with each of said slots being severally registrable with an edge of the tape as needed for wear-replacement. The plug member may be removed and replaced at the end of the useful slot life without discarding the mounting plate. 
     Having thus summarized the invention, it will be seen that it is a preferred object thereof to provide an elevator tape guide of the general character described herein which is not subject to the previously mentioned limitations. 
     A preferred object of this invention is to provide an elevator tape guide with a replaceable slot plug member for more effective serviceability and improved maintenance management. 
     A further preferred object to this invention is to provide an elevator tape guide having a plug member with plural tape slots for expeditious tape slot substitution. 
     A still further preferred object of the present invention is to provide an elevator tape guide that is practical in use, reliable in operation, relatively simple in design, and economical to manufacture. 
     With these ends in view, the invention finds embodiment in certain combinations of elements and arrangements of parts by which the aforementioned preferred objects and certain other objects are hereinafter attained, all as more fully described with reference to the accompanying drawings and the scope of which is more particularly indicated in the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompany drawings, in which is shown an exemplary embodiment of the invention: 
     FIG. 1 is an isolated perspective view illustrating an elevator cab, a position sensor, and an elevator hoistway tape within an elevator hoistway; 
     FIG. 2 is an elevational view, to an enlarged scale, taken substantially along line  2 — 2  of FIG. 1 showing a set of tape guides engaging the tape; 
     FIG. 3 is an elevational view to an enlarged scale taken along line  3 — 3  of FIG. 2 illustrating the tape guide and showing a set of plug members within a mounting plate and the hoistway tape received within a guide slot of the respective plug members; 
     FIG. 4 is a sectional view in elevation taken along line  4 — 4  of FIG. 3 showing in detail the plug member accommodated within the mounting plate with the hoistway tape engaging the guide slots; 
     FIG. 5 is a sectional view to an enlarged scale taken substantially along line  5 — 5  of FIG. 3 further illustrating the tape guide slots; and 
     FIG. 6 is an exploded perspective view, to an enlarged scale, showing the plug member removed from recess in the mounting plate. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With specific reference now to the figures in detail, it is stressed that the particulars shown are by way of example and for the purposes of illustrative discussion of the preferred embodiment of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show aspects of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings make it apparent to those skilled in the art how the several forms of the invention may be embodied in practice. 
     Referring now in detail to FIG. 1 of the drawings, there is shown an elevator cab  10  within an elevator hoistway, also shown is a hoisting cable  12 , a set of guide rails  14 , a sensor unit  16 , and a suspended hoistway tape  18 . The hoistway tape  18  is a steel band typically about 3 inches in width by 0.020 inches in thickness. In the illustrative embodiment, a series of apertures  17  in the tape  18  provide detection indicia for use by the sensor unit  16  as the elevator cab  10  moves relative to the stationary tape  18 . 
     Referring now to FIG. 2, it will be seen that a bracket member  20  is affixed to the sensor unit  16  within the tape travel path. Two sets of opposed elevator tape guides  22  are mounted to the bracket member  20  typically by removable screw fasteners. The tape guides  22  are of identical construction and will be referred to in the singular with regard to this description. 
     As best shown in FIG. 3, the tape guide  22  is comprised of a substantially rectangular mounting plate  24  preferably aluminum stock, having a length dimension of approximately 3.5 inches, a width dimension of approximately 1 inch and a depth dimension of approximately 0.375 inches. 
     The mounting plate  24  includes two threaded openings  26  for securement to the bracket member  20  by appropriate screw fasteners (not shown). The mounting plate  24  further defines a tape channel  28  extending along a longitudinal axis and corresponding to the path of travel of the hoistway tape  18 . By way of example, the tape channel  28  is approximately 0.125 inches in width and extends to a depth of about 0.3 inches. It should also be noted that the tape channel  28  is not intended to provide close tolerance for the tape  18 . Additionally, two recesses  30  extend transversely through the mounting plate  24 . The tape channel  28  intersects with the recesses  30  as will be further discussed herein. The recesses  30  are adapted to accommodate a respective plug member  32 . The plug member  32  is substantially cylindrical and defines a head section  34  and a stem section  36 . The plug member  32  is typically comprised of Nylatron or similar nylon composition material having a low coefficient of friction. The diametrical dimension of the head is about 0.75 inches and the maximum diametrical dimension of the stem is about 0.65 inches. As further shown, the circumference of the head section  34  is defined by opposed chord segments  38 . 
     Additionally, a set of tape slots  40 ,  42  extend transversely across the surface of the head section  34 , through the head section  34  and partially through the stem section  36  as shown in FIG.  5 . The tape slots  40 ,  42  are parallel to each other and to the chord segments  38 . 
     The recess  30  is defined by a transverse bore extending through the mounting plate  24 . The bore includes an internal wall having a necked-down portion  44  which defines a shoulder  46  being adapted for abutting contact with the head section  34  when the plug member  32  is seated in the recess  30 . It should further be noted that the recess  30  also contains a linear wall portion  48  in correspondence with the chord segment  38 . 
     When the plug  32  is snugly-seated within the recess  30 , the directionally interfitting relationship between the linear wall  46  and chord section  38  provide for self-alignment of one of the tape slots  40 ,  42  with the tape channel  28  (See FIG.  3 ). Furthermore, the respective surface of the plug member  32  and the mounting plate  24  will be coincidental. 
     The tape slots  40 ,  42  can typically have a width dimension within the range of 0.025 inches to 0.040 inches and a length dimension of about 0.7 inches. The tape channel  28 , can typically have a width dimension of approximately 0.100 inches to 0.150 inches. 
     In order to facilitate the insertion of the plug member  32  into the recess  30 , a margin  50  of the recess  30  at the intersection with an upper surface of the mounting plate  24  is chamfered; typically 0.040 inches by 45°. 
     With regard to use of tape guide  22 , if, for example, the tape slot  40  requires replacement due to wear changes, the plug member  32  can be removed by unscrewing the mounting plate  24  from the bracket member  20 . A pressure is applied on the stem section  36  in the direction of the head section  34  to release the plug member  32 . The plug member  32  can then be repositioned such that the alternative tape slot  42  is aligned with the tape channel  28  and the plug member  32  is then reinserted in the recess  30  for snug-fitted seating. As previously discussed, the cooperation between the linear wall  48  and the chord segment  38  provide for self-alignment of the plug member  32  during reinsertion. When the tape slot  42  reaches the end of its useful life, the plug member  32  may be removed and replaced by a substitute plug member without discarding the mounting plate  24 . 
     It should be further apparent that the recess  30  and the plug member  32  can have different slot configurations and that the plug member  32  can, for example, be designed for multiple-positioned seating with alternative tape slot patterns. In this regard, a circular plug member can be adapted with guide slots oriented in al multiple diametrical pattern requiring angular displacement for registering a selective tape slot. 
     The present embodiment however, is preferred in that it simplifies the installation requirements for an elevator mechanic and thus eliminates potential errors. Although the mounting plate:  24  must be unfastened to remove and/or replace the plug member  32 , it is within the scope of this invention to provide a tool for removing the plug member  32  without having to unfasten the plate  24 . 
     It should thus be seen that there is provided an elevator tape guide which achieves the various preferred objects of this invention and which is well adapted to meet conditions of practical use. Since other various possible embodiments might be made of the present invention or modifications might be made through the exemplary embodiment set forth above, it is to be understood that all materials shown and described in the accompanying drawings are to be interpreted as a illustrative and not in a limiting sense.