ELEVATOR PIT SAFETY APPARATUS FIELD OF THE INVENTION [001] The present invention relates to a safety apparatus installed in the pit volume of an elevator hoistway for preventing a worker from encountering the descending counterweight.

BACKGROUND OF THE INVENTION [002] Traction elevator systems are well known and widely used throughout the world. As shown schematically in Fig. 5, such systems comprise an elevator car 1 moving vertically within a hoistway shaft 4. The car is suspended and moved in the vertical direction by a rope 3 which passes over a driven sheave 5 and diverter sheave 6. In the system shown in Fig. 5, the rope 3 is connected to a counterweight 2 that counterbalances the weight of the elevator car 1 and moves oppositely within the hoistway 4. A pit volume 7 is shown disposed at the lower end of the hoistway 4.

[003] During routine and other maintenance tasks, it is necessary and common for elevator service personnel to enter the pit volume 7. It is frequently desirable during such maintenance tasks to continue to permit the elevator system to operate in the upper portion of the hoistway so as to avoid inconvenience to building tenants, visitors and other passengers.

Such operation may be permitted, provided appropriate safety steps are taken to protect maintenance personnel during the time they are present in the pit volume 7.

[004] One such safety step known in the prior art is illustrated in Fig. 6, which is a plan view of a simple traction system as shown in Fig. 5. The car 1 and counterweight 2 each vertically traverse respective ascent and descent areas 11,9 within the hoistway 4 and the included pit volume 7. For a maintenance worker present in the pit volume 7, it is essential to prevent the car 1 from descending into the pit volume as the descent area 11 of the car 1 would clearly occupy most of the available area. However the counterweight descent area 9 is relatively small, and it is frequently permitted to allow the counterweight 2 to descend into the pit volume 7 while maintenance personnel are present, thus permitting the elevator system to service the uppermost floor of the building. In the illustrated arrangement of Fig. 6, personnel barrier 8 is shown disposed between the counterweight descent area 9 and the remainder of the pit volume 7, thereby effectively separating maintenance personnel in the pit from possible contact with the counterweight 2.

[005] All such measures as shown in Fig. 6 are effective, recent market demands and advances in elevator technology have resulted in increased demand for more efficient utilization of hoistway area, as measured by the relative area within the hoistway occupied by the elevator car 1 and counterweight 2. As can be seen from Fig. 6, the personnel barrier 8 occupies a portion of the hoistway volume. By eliminating the volume occupied by the personnel barrier 8, it is possible to increase the size of the elevator car 1 or, alternatively, decrease the plan area of the hoistway 4, in either case achieving the desired increased hoistway utilization efficiency.

DISCLOSURE OF THE INVENTION [006] According to the present invention, a movable protective personnel barrier is provided in the pit volume of a traction elevator hoistway. The barrier moves, in response to the presence of the descending counterweight, from a first, retracted position disposed within the counterweight descent area to a second, deployed position outside of the counterweight descent area.

[007] Further according to the present invention, a deployment means is provided, actuable upon descent of the counterweight into the pit volume, for moving the barrier from the first position into the second position. Still further according to the present invention, a retracted means is provided to move and hold the barrier in the first position when the counterweight departs for is absent from the pit.

[008] Other objects and advantages of the apparatus according to the present invention will be apparent upon careful review of the following description, and the appended claims and drawing figures.

BRIEF DESCRIPTION OF THE DRAWING FIGURES [009] Fig. 1 shows a schematic horizontal elevation of a safety apparatus according to the present invention in a partially deployed state.

[010] Fig. 2 shows the apparatus of Fig. 1 in a fully retracted state.

[0 11] Fig. 3 shows the apparatus of Fig. 1 in a fully deployed state.

[012] Fig. 4 shows a plan view of the apparatus of Fig. 1 and a fully deployed state.

[013] Figs. 5 and 6 show a traction elevator system having a stationary personnel barrier according to the prior art.

DETAILED DESCRIPTION [014] Referring to the drawing figures, and in particular to Fig. 1, a safety apparatus according to the present invention, and the operation thereof, will be described. Fig. 1 shows a reduced area hoistway 104 having a pit volume 7 disposed at the lower end thereof.

Reference numerals 9 and 11 denominate portions of the hoistway 104 and pit volume 7 occupied by the car descent area 11 and the counterweight descent area 9, as illustrated above in Fig. 6.

[015] As can be seen in Fig. 1, a maintenance worker 26 is shown present in the pit volume 7, primarily working within the car descent area 11. The lower edge of the counterweight 2 is shown at the upper portion of the pit volume 7, as if, for example, the counterweight 2 were descending into the pit volume 7. According to the present invention, a personnel barrier 108, comprising a screen, shield, fence, or other substantially planar barrier or plate is disposed between the counterweight descent area 9 and the remaining space in the pit'volume 7 occupied by the worker 26. This personnel barrier 108 is moved laterally 28 into a second, deployed position by a deployment means activated by the presence of the counterweight 2 within the pit volume 7.

[016] In the illustrated example, this deployment means comprises a cam 15 having a sloping cam surface 15a which contacts a roller 16 mounted on the barrier 108. As the counterweight 2 descends into the pit volume 7, the roller 16 encounters a sloping area 15 a upon the counterweight cam 15, driving the barrier 108 laterally 28 and out of the counterweight descent area 9. Thus, the maintenance worker 26 is protected by the barrier 108 from the counterweight 2 as it enters the pit volume 7. This process is reversed as the counterweight 2 ascends upwards from the pit volume 7 whereupon the cam 15 is withdrawn from contact with the roller 16 and the personnel barrier 108 is retracted into a first position within the counterweight descent area 9 by biasing means, such as the resilient members or springs 14 as shown.

[017] Fig. 2 further illustrates the arrangement of the apparatus according to the present invention by depicting the elevator system in a condition in which the elevator car 1 has descended to its lowermost position, within the pit volume 7. For the purposes of this illustration, a phantom outline of the counterweight 2 is also show. The elevator car 1 occupies the car descent area 11 as shown. The personnel barrier 108 according to the present invention is shown in its first, retracted position disposed within the counterweight descent area 9. As can be seen from the illustration, the car and counterweight descent areas 11,9 may be disposed in close proximity without the need to accommodate the presence of a stationary personnel barrier in the pit volume 7 as in the prior art arrangement of Fig. 6. This ability to use a greater portion of the hoistway 104 as compared to the prior art increases the utilization efficiency of an elevator system having a pit safety apparatus according to the present invention.

[018] Fig. 3 further illustrates the arrangement of Fig.'s 1 and 2, in this instance showing the counterweight 2 at its lowest position within the hoistway 104 and pit volume 7. The barrier 108 is shown fully deployed into its second position, having a pair of rollers 16 engaged with the cam 15. The deployed barrier 108 is shown disposed wholly within the car descent area 11.

[019] Fig. 4 is a further illustration of the deployed barrier 108 in a plan view, further illustrating position of the barrier within the car descent area 11. Counterweight guide rails 13, and car guide rails 12 are also shown for illustrative purposes. The guide rails 12,13 are used to the laterally position the car 1 and counterweight 2 within the hoistway 104 as is well known in the prior art.

[020] The advantages of the illustrated structure should now be readily apparent. By providing a movable personnel barrier 108, moving between a first, retracted position within the counterweight descent area 9 and a second, deployed position outside of said counterweight decent area, the safety apparatus according to the present invention permits higher utilization of the hoistway footprint area while providing the benefit of a prior art, fixed barrier. Further, by actuating the deployment by mechanical means 15,16 in response' to the presence of the counterweight 2 in the pit volume 7, the safety apparatus according to the present invention operates without the need for sensors, electronic controls, or other, more complicated means. The simple, direct mechanical actuation achieves reliable operation with minimal expense and complexity.

[021] It must further be appreciated that the embodiments of this invention are not limited to the one explained above. As an example, the barrier 108 has been described as supported and retracted by springs were teen, however it is within the scope of the present invention to provide a spring loaded link arrangement to support and retract said barrier, as well as various well-known equivalents such as horizontal tracks and rollers, pneumatic retractors, etc. It may equally be appreciated that the cam and roller arrangement described above may be equivalently arranged by placing the cam on the protective barrier 108, and the rollers on the counterweight 2. As will also be appreciated by those skilled in the art, the rollers they equivalently be replaced by low friction slides or shoes. Likewise, the cam and rollers may be replaced by a contact linkage disposed in the descent area 9 of the counterweight 2, whereby the descent of the counterweight into the pit volume 7 drives the personnel barrier 108 into the second, deployed position.

We claim: