Elevator – industrial lift truck – or stationary lift for vehicle – With barrier for regulating access to load support – Includes motor or motor driven linkage for shifting barrier
Reexamination Certificate
1999-08-30
2001-05-01
Salata, Jonathan (Department: 2837)
Elevator, industrial lift truck, or stationary lift for vehicle
With barrier for regulating access to load support
Includes motor or motor driven linkage for shifting barrier
C187S391000
Reexamination Certificate
active
06223861
ABSTRACT:
TECHNICAL FIELD
This invention relates to recognizing when a person has made access to an elevator hoistway other than into a car, and controlling elevator operation for safety.
BACKGROUND ART
Persons that enter a hoistway, such as elevator mechanics, building maintenance personnel, and unauthorized persons such as vandals, may suffer serious and fatal accidents when the elevator moves unexpectedly at normal speed. Such accidents most commonly occur in the overhead or the pit where the person is crushed by the sudden movement of the elevator. This problem is aggravated in systems in which the hoisting machine and/or the controller are located in the pit. As architects continue to try to reduce the size of the overhead and the depth of the pit, the problem becomes even worse.
Heretofore, elevator systems have not made provision to recognize when persons have entered the hoistway, relying instead on the mechanic moving an inspection switch from the normal mode of operation position to the inspection mode of operation position. This is typically achieved when the elevator is parked at one floor, the mechanic forces the hoistway doors open on the next higher floor, the mechanic thereupon enters the hoistway on the roof of the cab, and usually transfers the inspection switch from the normal mode of operation to the inspection mode of operation, and then controls the motion of the cab by means of switches on the inspection box. When the mechanic returns the maintenance switch to the normal mode of operation, the hoistway door switch may be shorted out or defective so it appears that the safety chain is made, or if the mechanic failed to put the inspection switch into the inspection mode, the elevator may start up for some reason, which has resulted in crushing the mechanic between the top of a car and the sill of the hoistway door.
A partial solution to this known to the prior art is requiring a sequence including that a hoistway door shows as being open, followed by the stop switch being in the stop position, then the inspection switch being transferred to normal, and then the hoistway doors all being closed. However, this still does not inform the system when someone has entered the hoistway in the first place, which is still only learned when the inspection switch is transferred to the inspection mode, whereby any mechanics within the hoistway are at risk of being crushed. Furthermore, none of these systems detect the case when the mechanic enters the pit (where he cannot activate the inspection switch).
DISCLOSURE OF INVENTION
Objects of the invention include detecting any entry of personnel into an elevator hoistway, whether it be in the pit or in the overhead; substantially eliminating the possibility of a person being crushed by unexpected movement of the elevator when operating either at inspection speed or normal speed; providing safety in systems which utilize reduced overhead and/or pit dimensions for traditional as well as machine-room-less elevators; providing a hoistway access control that is sufficiently safe so as to achieve regulatory code approval.
According to the present invention, the condition of the hoistway doors and the elevator door are continuously monitored; the opening of a hoistway door unaccompanied by opening of the car door being an indication of hoistway access; the car then is moveable only at inspection (slow) speed by utilizing controls on the car top; restoration to normal is achieved only by either returning the inspection switch on the car top to normal operation while a hoistway door is open, and then closing the hoistway doors, or engaging an external reset (outside the hoistway) while the landing doors are all closed, or a combination of both. In accordance further with the invention, inspection speed limit switches are installed near the top and bottom of the hoistway positioned so that if operated while the elevator is traveling at inspection speed, the car will stop at a position which leaves a person ample room (over six feet) from the hoistway overhead or the pit floor.
Other objects, features and advantages of the present invention will become more apparent in the light of the following detailed description of exemplary embodiments thereof, as illustrated in the accompanying drawing.
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patent: 4936419 (1990-06-01), Stadler
patent: 5476157 (1995-12-01), Todaro
patent: 5549179 (1996-08-01), Herkel et al.
patent: 5644111 (1997-07-01), Cerny et al.
patent: 5780788 (1998-07-01), Eschenbrenner et al.
patent: 6138798 (2000-10-01), Macuga
patent: 984556 (1965-02-01), None
Otis Elevator Company
Salata Jonathan
LandOfFree
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