Abstract:
An elevator system ( 20 ) including: an elevator car assembly ( 2 ); and a cable ( 7 ) interconnecting the assembly ( 2 ) with a counterweight ( 8 ), wherein the cable ( 7 ) is coupled to the assembly ( 2 ) at a lower region ( 23 ) thereof.

Description:
FIELD  
       [0001]     This invention relates to an elevator system, particularly for use with a cantilevered elevator car.  
       BACKGROUND  
       [0002]     A known form of elevator system  1 , as shown in  FIG. 1 , is disclosed in European Patent No. 1216949. The system  1  includes a cantilevered elevator car assembly  2  which is driven up and down an elevator shaft  3  by a motor  4  which is positioned at a top end  5  of the shaft  3 . The motor  4  has a drive sheave  6  which engages and drives a rope or cable  7 , which passes over the sheave  6  and interconnects a counterweight  8  at one end  9  and a top cross-beam  10  of a frame  11  of the car assembly  2  at the other end  12 . Such a system  1  provides a space saving advantage in that positioning of the motor  4  at a top end of the elevator shaft  3  dispenses with the need for a separate motor room at a base of the shaft  3 .  
         [0000]     Object  
         [0003]     The present invention seeks to provide an improved elevator system.  
       SUMMARY OF THE INVENTION  
       [0004]     In accordance with the invention, there is provided an elevator system including: 
        an elevator car assembly; and     a cable interconnecting the assembly with a counterweight,     wherein the elevator car assembly is cantilevered and the cable is coupled to the assembly at a lower region thereof.        
 
         [0008]     Preferably, the cable is connected to a lower structural beam of the assembly.  
         [0009]     Preferably, the system includes a motor for driving the cable, wherein the motor is positioned so as to be laterally adjacent the car assembly, when the lower region of the assembly is adjacent a top terminal landing serviced by the system.  
         [0010]     Preferably, the motor is arranged in a position lower than a roof of the assembly when a floor of the elevator car assembly is level with the top terminal landing.  
         [0011]     In another aspect, there is provided a method for supporting and driving a cantilevered elevator car assembly including connecting an end of a drive cable to a lower region of the assembly. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     The invention is described in more detail with reference to the accompanying drawings, in which:  
         [0013]      FIG. 1  is a diagrammatic side view of a known elevator system; and  
         [0014]      FIG. 2  is a diagrammatic side view, illustrating the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0015]     An elevator system  20  is now described with reference to  FIG. 2 . The system  20  has features similar to those shown in  FIG. 1  and like reference numerals are used to denote like parts.  
         [0016]     Similarly to system  1 , the elevator system  20  includes a cantilevered elevator car assembly  2  coupled to a counterweight  8  via a rope or cable  7 , which is driven by a motor  4 , to allow the car assembly  2  to travel up and down elevator shaft  3 . The cable  7  is, however, coupled to the elevator car assembly  2  at a lower region  23  of the assembly  2 , as compared to the top cross-beam  10  shown in  FIG. 1 . More particularly, the cable  7  is connected to sockets  24  which are in turn coupled to a lower structural beam  25  of the assembly  2  so as to provide a length of cable ‘L’ between the motor  2  and the sockets  24 .  
         [0017]     A further difference between the systems  1  and  20  is that the motor  4  is supported in spaced relation to the top end  5  of the shaft  3 . The motor  4  can, in fact, be positioned further away from the end  5  of the shaft  3  such as in the location shown in dashed outline  30 , where the motor  4  is below a roof  26  of the assembly  2  and laterally adjacent the assembly when level with a top floor  22  serviced by the system  20 .  
         [0018]     In relation to the positioning of the motor  4  relative to the car assembly  2 , a certain minimum distance needs to be maintained between the motor  4  and the end  12  of the cable connected to the car assembly  2 , to accommodate overrun of the car assembly and the like. The specific length of cable required to accommodate the overrun is calculated by taking into consideration a number of factors such as a counterweight buffer stroke, which is the displacement distance of a buffer at a base of the elevator shaft, which is used to arrest downward displacement of the counterweight. Since the cable  7  is connected to the car assembly  2  at the lower region  23 , the relevant overrun can be readily accommodated within the length ‘L’ of cable  7 . The motor  4  may be placed at a substantially lower location as a result, as compared to the location of the motor  4  of  FIG. 1 , where the placement of the motor needs to be above the car assembly  2  itself.  
         [0019]     The arrangement of the system  20  may thereby provide a number of advantages. Flexibility exists in the specific placement of the motor  4  and the motor  4  may be more readily accessed by a person standing on the roof  26 . Also, the overall height requirements for the shaft  3  may be reduced which could perhaps result in some economic advantage in the form of space and construction savings, such as by allowing the top end  5  of the shaft  3  to be lowered, or in the form of allowing an additional floor to be added and serviced by the system  20 , whilst still complying with initial building height restrictions.  
         [0020]     To further illustrate the potential height advantage provided by the system  20 , a standard minimum lift shaft overrun calculation was made for comparison with the system  1 . The minimum lift shaft overrun may be taken as a distance ‘D’ between the top floor  22  served and the top end  5  of the shaft  3 . The calculations were conducted for a system intended to carry  13  passengers at 1.0 m/s with: a counterweight buffer stroke of  80  mm; a counterweight buffer clearance of 450 mm, below the motor or its support; and a top-of-car person clearance of 1570 mm, which is a clearance required for a maintenance person standing on top of the car assembly  2 . The minimum lift shaft overrun for the system shown in  FIG. 1  was found to be 4680 mm while that required for system  20  was only 3960 mm, which indicates a clear height advantage may be realised utilising the present invention.  
         [0021]     The invention has been described by way of non-limiting example only and many modifications and variations may be made thereto without departing from the spirit and scope of the invention described.