Abstract:
An elevator installation includes a car within a shaft, a buffer mounted in a pit of the shaft and a barrier located in the pit surrounding or within an area wherein a vertical clearance between the pit floor and the car or equipment mounted thereon is less than a regulatory threshold value when the car fully compresses the buffer. The barrier acts to physically deter personnel within the pit from inadvertent presence in the area of reduced vertical clearance.

Description:
The present application is a divisional of application Ser. No. 11/866,634 filed Oct. 3, 2007 now abandoned. The present invention relates to elevators and, in particular, to a barrier located in an elevator to maintain the safety of personnel working in a pit of reduced depth. 
    
    
     BACKGROUND OF THE INVENTION 
     There are increasing pressures on the elevator industry to reduce the space occupied by elevator installations within buildings. One solution is to reduce the depth of the pit of the elevator shaft, however, regulations such as European Standard EN81-1:1998 specify that when an elevator car rests on its fully compressed buffers, there shall be a specified minimum free vertical clearance between the pit floor and the lowest parts of the car. There are exceptions to these rules, such as for toeguards, roller guides, guide shoes and safety gear, all of which are generally mounted on the outside periphery of the car. A common situation is depicted in  FIGS. 1 to 3 . In this example, the elevator car  1  is supported by means of an underslung pulley box  2  on ropes  4 . The ropes  4  are driven by a traction sheave (not shown) to move the car  1  along guide rails (not shown) mounted to opposing shaft walls  6 . A buffer  16  is mounted in the pit  12  of the shaft  10  to arrest the car  1  should it travel beyond its normal travel limit (e.g. the lowest landing). When the car  1  rests on the fully compressed buffer  16 , as shown specifically in  FIG. 3 , a minimum free vertical clearance C exists between the pit floor  14  and the lowest part of the car  1 , which in this instance is the pulley box  2 . Although the toeguard  8  actually extends below the pulley box  2 , as mentioned above, the regulations allow it to be excluded from consideration. 
     The objective of the present invention is to reduce the pit depth and thereby the minimum free vertical clearance between the pit floor and the lowest parts of the car while maintaining the safety of any personnel working in the pit. 
     BRIEF DESCRIPTION OF THE INVENTION 
     This objective is achieved by an elevator installation comprising a car within a shaft, a buffer mounted in a pit of the shaft and a barrier located in the pit surrounding or within an area wherein a vertical clearance between the pit floor and the car or equipment mounted thereon is less than a regulatory threshold value when the car fully compresses the buffer. Accordingly, the barrier acts to physically deter personnel within the pit from inadvertent presence in the area of reduced vertical clearance. 
     Preferably, the barrier is height-adjustable and biased to its highest position. Thus, the barrier can have a height greater than the reduced vertical clearance but will not be damaged if the car travels into it. Furthermore, even if a maintenance person were to get a hand, for example, trapped between the car and the barrier, the height-adjustability of barrier ensures that such entrapment will not cause personal injury. 
     The barrier may be flexible and preferably elastically deformable. Such a barrier may take the form of an inflated balloon. 
     Alternatively, the flexible and deformable barrier may comprise two flexible uprights interconnected by linkage means such as a net. Should the car descend into the barrier, the flexible uprights will automatically deform to a reduced height. Since this barrier contains no complicated moving parts it provides a relatively low cost solution. 
     Preferably, the flexible uprights are formed from doubled-over elements so that if the car descends into the barrier each upright deforms outwards in mutually opposing directions. Accordingly, the greater the deformation of the uprights, the greater the area effectively protected by the barrier. 
     Alternatively, the barrier may comprise a pair of channels each retaining at least one slider, and linkage means secured to and interconnecting the sliders of the opposing channels. Accordingly, if the car descends into the barrier, the linkage means and sliders moved downwards in the channels against the biasing force. 
     The linkage means may have the form of rigid bars, wires, belts or a net. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is hereinafter described by way of specific examples with reference to the accompanying drawings in which: 
         FIG. 1  is a partial, rear diagrammatic elevation view of a pit of an elevator installation according to the prior art: 
         FIG. 2  is a partial, side diagrammatic elevation view of the pit of  FIG. 1 ; 
         FIG. 3  is an elevation view corresponding to  FIG. 2 , illustrating the elevator car compressing the buffer: 
         FIG. 4  is a partial, rear diagrammatic elevation view of a pit of an elevator installation in accordance with a first embodiment of the present invention; 
         FIG. 5  is a partial, side elevation view of the pit of  FIG. 4 ; 
         FIG. 6  is a partial, side elevation view of a pit of an elevator installation in accordance with a second embodiment of the present invention; 
         FIG. 7  is a view corresponding to  FIG. 6  illustrating the elevator car engaging the barrier; 
         FIG. 8  is a view corresponding to  FIG. 6  illustrating the elevator car compressing the buffer: 
         FIG. 9  is an elevation view of a barrier according to a third embodiment of the invention; 
         FIG. 10  is an exploded perspective view of the barrier of  FIG. 9 ; and 
         FIG. 11  is an illustrative sectional view of a barrier according to a fourth embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following description, for the avoidance of unnecessary repetition, features of the invention which are common to more than one embodiment have been assigned a common reference numeral and where appropriate share a common description. 
       FIGS. 4 and 5  illustrate an elevator installation according to a first embodiment of the present invention. While the arrangements of the car  1  within the shaft  10  are identical to those previously described with respect to the prior art of  FIGS. 1 and 2  respectively, areas on the pit floor  14  directly beneath the underslung pulley box  2  or other components mounted under the car are clearly designated as such as being marked with a tape  18  of diagonal stripes of contrasting colours (e.g. yellow and black or red and white). Preferably, words such as “DANGER LOW CLEARANCE” can be printed in the tape  18 . Furthermore, a barrier  20  is also erected in the pit  12  directly beneath the underslung pulley box  2 . The barrier  20  comprises a pair of opposing flexible uprights  22  mounted to the pit floor  14  with an interconnecting net  24 . Accordingly, when maintenance personnel are in the pit  12 , the tape  18  and the barrier  20  both act as visible warnings that the area under the pulley box  2  could potentially have a reduced vertical clearance. Moreover, the barrier  20  acts to physically deterrent personnel within the pit  12  from inadvertently working in the area of reduced vertical clearance. 
     If at any time the pulley box  2  should come into engagement with the barrier  20 , the barrier  20  will be deflected due to the flexible nature of the uprights  22 . Hence, even if a maintenance person were to get a hand, for example, trapped between the pulley box  2  and the barrier  20 , the barrier is sufficiently flexible to accommodate the body part without causing damage. 
     Given the potential central location of the barrier  20  and the fact that it may essentially span the entire width of the pit  12 , the maintenance personnel will inherently need to cross the barrier  20  occasionally; the barrier  20  is easily deformable to enable them to do so. However, these transitions across the barrier  20  make up only a small amount of the total time the maintenance personnel spend in the pit  12 . The large majority of maintenance operations carried out in the pit  12  will actually typically require the person to face away from the barrier  20  which in turn generally means that their arms will also be projecting away from the barrier  20 , in which case the person will only come into contact with the barrier if he backs into it; the normal reaction to that is to step slightly away and out of the reduced clearance area. Even the majority of work on a pulley box  2  is carried out from the side rather than underneath. Hence, a relatively low barrier, perhaps at knee height (≈500 mm), would be sufficient to effectively deter personnel from inadvertent presence in the area under the pulley box  2 . 
       FIGS. 6 to 8  illustrate an alternative barrier  30  which is similar to the barrier  20  of the first embodiment but, in this instance, each of the uprights  32  is formed with a folded or doubled-over element with both ends secured to the pit floor  14 . The doubled-over uprights may be sealed along the edges to form balloons. As shown specifically in  FIG. 7 , as the pulley box  2  descends upon the barrier  30 , the doubled-over uprights  32  and the interconnected net  24  are deflected outwards. Accordingly, any person standing adjacent to the barrier  30  is also thrust away from the reduced clearance area under the pulley box  2 . The car may continue to descend, and thereby further deform the barrier  30  until it rests on the fully compressed buffer  16 , as shown in  FIG. 8 . 
     Since the barriers  20 ,  30  of both embodiments effectively deter personnel from inadvertent presence in the area under the pulley box  2 , the regulatory minimum free vertical clearance C may now be determined as existing between the pit floor  14  and the car  1 , rather than between the pit floor  14  and the underslung pulley box  2  (as in the prior art of  FIG. 3 ), enabling a space saving within the elevator installation corresponding to the height S of the pulley box  2 . 
     A further embodiment of the invention is illustrated in  FIGS. 9 and 10 . In this embodiment, the barrier  40  comprises a pair of opposing uprights in the form of U-shaped channels  42 . The channels  42  may be secured at their bases to the pit floor  14  as in the previously described embodiments, or, alternatively, they can be mounted on opposing side walls  6  of the shaft  10 . Each channel  42  retains a plurality of sliders  46  connected to a net  44 . The uppermost slider  46  in each channel  42  is biased upwards by a spring  48 . 
     If at any time the pulley box  2  descends into the net  44 , the net  44  will descend therewith against the biasing force of the spring  48 . 
       FIG. 11  shows another alternative embodiment of the invention, wherein the upward bias of the net  44  is provided by a counterweight  50 . The uppermost slider  46  within each channel  42  is attached by a wire or rope  54 , which passes over a pulley  52  to the counterweight  50 . 
     Although all of embodiments above describe the use of a barrier under the underslung pulley box  2 , it will be appreciated that the barrier can be used to deter personnel from inadvertent presence in any area of the pit  12  which has the possibility of reduced clearance. 
     As previously described, the area under the pulley box  2  is a relatively maintenance intensive area. If, on the other hand, the reduced clearance area is within a high maintenance intensive sector of the pit  12 , then a relatively high barrier, perhaps at shoulder height (≈1500 mm), should be employed in or surrounding the reduced clearance area to positively prevent personnel from inadvertent presence in that area. 
     If the person needs to specifically work in a designated reduced clearance area, he can easily collapse the barrier to do so. 
     Although a net  24 ,  44  has been used in the preferred embodiments to interconnect the uprights  22 , 32  or the channels  48 , will be readily appreciated that this can easily be replaced by other linkage means such as wires or rods.