Abstract:
A drive arrangement for an elevator car and a machine roomless elevator incorporates a machine having a drive sheave, a pair of right and left car side sheaves disposed beneath the car, a counterweight with a pair of top mounted sheaves, and a hoist cable including a plurality of ropes. The car is shifted to one side of the hoistway and the car guide rails are shifted forward in the hoistway in order to create a large pocket in a rear corner of the hoistway for the counterweight. In this manner, the elevator car can nest beside the machine in the top of the hoistway limiting the required top hoistway space and creating a minimal hoistway footprint.

Description:
RELATED APPLICATION 
       [0001]    This Application claims priority from provisional application Ser. No. 61,391,841, filed Oct. 11, 2010. 
       BACKGROUND OF THE INVENTION 
       [0002]    Elevators typically include a car guided for vertical movement within an elevator hoistway. Typically, a machine drives a rope around a series of sheaves driving the elevator car and a connected counterweight. Historically, the machine was mounted in a room above or beside the elevator hoistway. Thus, a good deal of additional space was required above or beside the hoistway, which is undesirable. 
         [0003]    More recently, so-called “machine roomless” (MRL) elevators have been designed. In such constructions, the machine is incorporated in a small space within the elevator hoistway. A separate room is not then required. 
         [0004]    Traditional MRL elevators, as shown in  FIG. 5  and  FIG. 6 , necessarily require the hoistway  10  to have an enlarged width of the hoistway for at least two reasons:
       1. With the machine  12  and the drive sheave  14  located between the car guide rail  16 L and the hoistway wall  10 L, extra space is required increasing the necessary width of the hoistway  10 .   2. With the car guide rails  16 R and  16 L and the car frame  28 R and  28 L approximately located at the front to back center of gravity of the car  22 , the counterweight  20  is confined to a limited space between the counterweight guide rails  18 F and  18 R. Since the counterweight  20  is confined in this manner between the counterweight guide rails  18 F and  18 R, the width of the hoistway  10  must necessarily increase in order to garner enough space for the counterweight  20 .       
 
         [0007]    Additionally, traditional MRL elevators exert extra pressure on the sides of the car guide rails  16 R and  16 L due to the car ropes  26  and car sheaves  24 R and  24 L being forward of the center of gravity of the car  22 . 
         [0008]    Additionally, traditional MRL elevators can penetrate the hoistway wall  10 L, as shown in  FIG. 5 , requiring special provisions outside the hoistway  10  for required fire isolation. 
         [0009]    Additionally, traditional MRL elevators can require structural reinforcement integrally in the building structure for handling the concentrated loading of the machine  12 . 
         [0010]    As an alternative, traditional MRL elevators may need extra space at the top of the hoistway, if the machine  12  is rotated 180 degrees, as illustrated in  FIG. 6 , to prevent penetration of the hoistway  10 . In this configuration, the machine resides over the car frame  28 L increasing the required space at the top of the hoistway  10  in order to maintain the proper clearance requirements. 
         [0011]    It is one object of the present invention to provide an improved machine roomless elevator capable of solving the above-mentioned problems in the prior art resulting in reduction of the pressure on the sides of the car guide rails, reduction of the need for additional hoistway width, support for the driving unit inside the hoistway, and reduction of the space necessary in the top of the elevator hoistway that is conventionally required for maintaining a top clearance between the ceiling of the elevator hoistway and the car, if stopped in its highest position in the elevator hoistway. 
       SUMMARY OF THE INVENTION 
       [0012]    In one disclosed embodiment of this invention, the car is shifted to one side within the hoistway, and the car guide rails are shifted forward in order to create a large pocket in a rear corner of the elevator hoistway for the counterweight. This component arrangement utilizes a roping design that uniquely allows the hoistway footprint to remain minimal. The machine is affixed atop the counterweight guide rails via a bedplate in a position so that the drive sheave connects the nearest car side sheave and the center line of the counterweight. On one end the hoist ropes are divided around a pair of counterweight sheaves mounted to a top of the counterweight and secured to the bedplate connecting the machine to the top of the counterweight guide rails, and on the other end, the hoist ropes are secured to a hitching device in the top of the hoistway on the far side of the car away from the counterweight. In this manner, the elevator car can nest beside the machine in the top of the hoistway limiting the required space at the top of the hoistway. In addition, this arrangement does not necessitate penetration of the hoistway wall. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a top view of an embodiment of an improved machine roomless elevator system. 
           [0014]      FIG. 2  is a side view of the counterweight and the counterweight roping detail of the embodiment of the elevator system of  FIG. 1 . 
           [0015]      FIG. 3  is a front view of the relationship of the elevator car and the counterweight and the car roping detail of the embodiment of the elevator system of  FIG. 1 . 
           [0016]      FIG. 4  is a side view of the elevator car at its vertically uppermost position of the embodiment of the elevator system of  FIG. 1 . 
           [0017]      FIG. 5  is a top view of a MRL of the prior art. 
           [0018]      FIG. 6  is a top view of an alternative MRL of the prior art. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0019]    One embodiment of the current invention is illustrated in  FIG. 1  through  FIG. 4 . However, the specific location of the car within the hoistway is not limited by the designs shown in these Figures. The side of the hoistway where the equipment is located is determined based on placement of the door opening therein. 
         [0020]    One embodiment of the current invention, as illustrated in  FIG. 1 , is an elevator without a machine room having a car  64  within a hoistway  50  movable upwardly and downwardly, a drive machine  52  with an associated drive sheave  54 , a counterweight  60 , a hoist cable  68  including a plurality of ropes, and associated sheaves  62 F,  62 R,  66 R, and  66 L which is described in greater detail below.
       The car  64 , the car frame  70 R and  70 L, and opposing car guide rails  56 R and  56 L are positioned proximate to the hoistway wall  50 R creating space for the counterweight  60  in the opposite rear corner.   The car frame  70 R and  70 L and opposing car guide rails  56 R and  56 L are positioned forward of the car sheaves  66 R and  66 L which are disposed under the car  64 .   A pocket is thus created in the space between the car  64  and the hoistway wall  50 L and between the car guide rail  56 L and the rear wall of the hoistway  50 Rr wherein the counterweight  60  is guided between the opposing counterweight guide rails  58 F and  58 R.   The available space allows for a counterweight  60  that is large enough to be fitted on top with a pair of sheaves  62 F and  62 R.   By this arrangement of components the counterweight  60  requires minimal side to side space thus precluding the need for the width of the hoistway  50  to be increased.   Since the counterweight  60  requires a reduced side to side space, the counterweight  60  and the car sheave  66 L can pass each other during up and down movement with sufficient clearance not to require additional width of the hoistway  50 .   The car sheaves  66 R and  66 L have parallel axes of rotation and are positioned on the same linear plane perpendicular to the hoistway side walls  50 R and  50 L under the car  64 .   Using the diameter of the drive sheave  54  as the radius and the center point of the counterweight  60  as an anchor, an arc is drawn to ascertain its intersection with the adjacent side of the car  64 . The point of intersection with the car  64  is the reference point for determining a perpendicular line connecting the hoistway side walls  50 R and  50 L. These radii, center points, and arcs may vary depending on the arrangement of the components of the elevator system.   This perpendicular line is the center line wherein the parallel axes of rotation of the car sheaves  66 R and  66 L is located.   The driving machine  52  is positioned in the top of the hoistway on top of the counterweight guide rails  58 F and  58 R so that the drive sheave  54  connects the two reference points previously described of the center point of the counterweight  60  and the point of intersection with the car  64  where the car sheaves  66 R and  66 L are located.   This arrangement, wherein the forward side of the drive sheave  54  connects vertically with the car sheave  66 L and the rear side of the drive sheave  54  connects vertically with the counterweight  60 , assures that all of the ropes of the hoist cable  68  have a substantially vertical drop.   Additionally, this arrangement positions the car sheaves  66 R and  66 L along a side to side line that is proximate to the front to back center of gravity of the car  64  thus minimizing the side pressure on the car guide rails  56 R and  56 L.       
 
         [0033]    One embodiment of the current disclosure, as illustrated in  FIG. 2 , depicts a specific roping arrangement associated with the counterweight  60 , the machine  52 , the associated drive sheave  54 , the counterweight sheaves  62 F and  62 R, and the machine bedplate  72 .
       As described previously the hoist ropes  68  are engaged over the drive sheave  54  associated with the machine  52  in the top of the hoistway  50  dropping vertically from the rear side of the drive sheave  54  at approximately a center line of the counterweight  60 .   The counterweight  60  is sized so that it is fitted on top with two counterweight sheaves  62 F and  62 R.   The counterweight  60  is guided by a pair of opposed guide rails  58 F and  58 R.   The machine is affixed in the top of the hoistway  50  on top of the counterweight guide rails  58 F and  58 R via a bedplate assembly  72 .   The hoist ropes  68  drop from the rear side of the drive sheave  54  passing under the two sheaves  62 F and  62 R and are secured to the bedplate assembly  72  that is affixed to the counterweight guide rails  58 F and  58 R with hitching devices  74 F and  74 R.   The hoist ropes  68  are divided approximately equally under the counterweight sheaves  62 F and  62 R and secured respectively to the bedplate assembly  72  and the hitching devices  74 F and  74 R.   The described counterweight roping arrangement suspends the counterweight  60  in a 2-to-1 roping arrangement on one end of the hoist cable  68 .       
 
         [0041]    One embodiment of the current invention, as illustrated in  FIG. 3 , depicts the specific roping arrangement associated with the car  64 , the machine  52 , the associated drive sheave  54 , and the car sheaves  66 R and  66 L.
       As described previously, the hoist ropes  68  are engaged over the drive sheave  54  associated with the machine  52  in the top of the hoistway  50  dropping vertically from the forward side of the drive sheave  54  to the car sheave  66 L.   The sheaves  66 R and  66 L associated with the car  64  are positioned under the car  64  creating an under slung car roping arrangement.   The hoist cable  68  drops vertically from the forward side of the drive sheave  54  to the car sheave  66 L passing under the car  64  around the opposite car sheave  66 R in a vertical path from the car sheave  66 R to a hitching device  74 C in the top of the hoistway  50 .   The described car roping arrangement suspends the car in a 2-to-1 roping arrangement on one end of the hoist cable  68 .   The hoist cable  68  is positioned within the clearance space between the car  64  and the counterweight  60 .   The car sheave  66 L nearest the counterweight  60  is positioned so that a minimal amount of the car sheave  66 L protrudes beyond the vertical plane of the car  64  in order to minimize the need for clearance space between the car  64  and the counterweight  60 .       
 
         [0048]    One embodiment of the current invention, as illustrated in  FIG. 4 , depicts the car  64  in its vertically uppermost position.
       As previously described, the machine  52  and bedplate assembly  72  are affixed to the top of the counterweight guide rails  58 F and  58 R in the top of the hoistway.   Since the substantially vertical drop of the hoist cable  68  from the forward side of the drive sheave  54  to the car sheave  66 L is aft of the car frame  70 L, the portion of the car frame  70 L which extends above the car  64  nests beside the machine  52  and bedplate assembly  72  when the car  64  is at its uppermost vertical point of travel.   It can be appreciated that the space in the top of the hoistway  50  is minimally impacted by this embodiment.       
 
         [0052]    As described herein a worker of ordinary skill in this art will readily recognize various modifications from a traditional machine roomless elevator in the current invention. It will be further recognized that the current embodiment resolves problems outlined in the prior art by reducing the pressure on the sides of the car guide rails, reducing the need for additional hoistway width, supporting the driving unit inside the hoistway space, and reducing the space in the top of the elevator hoistway required while maintaining the required top clearance in the vertical direction between the ceiling of the elevator hoistway and the car stopped in its highest position of the elevator hoistway.