Elevator – industrial lift truck – or stationary lift for vehicle – With monitoring – signalling – and indicating means
Reexamination Certificate
2002-01-29
2003-04-22
Salata, Jonathan (Department: 2837)
Elevator, industrial lift truck, or stationary lift for vehicle
With monitoring, signalling, and indicating means
C187S280000
Reexamination Certificate
active
06550585
ABSTRACT:
TECHNICAL FIELD
The invention pertains to an elevator exhibiting an elevator shaft, an elevator car which is movable inside the elevator shaft, and a safety installation which is designed in such a way that it can take the elevator out of service in a dangerous situation.
BACKGROUND ART
Everyday life, especially, in cosmopolitan areas, is no longer imaginable without elevators. Elevators are being employed for very diverse applications, e.g., for use in buildings with only relatively few floors (3 to 5 floors) and in relatively tall buildings of, sometimes, substantially more than 50 floors. Elevators are equipped with extremely diverse drive systems. There are those with a friction-driven hoisting motor, which, for instance, may be provided in the upper area of the elevator shaft. These types of elevators frequently are equipped with a counterweight unit that is suspended on the same hoisting cable as the elevator car, which runs in the opposite direction to the elevator car. In addition, there are those elevators, in particular, which are used to service only relatively few floors, so-called hydraulic elevators, with or without a counterweight, in which the elevator car is moved by a hydraulically moved pressure piston. Sporadically, there are also elevators in which the driver is provided on the elevator car directly and which is, for example, designed as a rack and pinion drive, or wheel and disk drive.
In all of these different elevator types, assuring that only maintenance staff or other authorized individuals enter the elevator shaft presents a fundamental problem. In order to solve this problem, elevators typically have a safety installation which is equipped with various sensors and which, upon detecting a dangerous situation—which is defined in accordance with specific prerequisites—will take the elevator out of service. The acuteness of this problem which, in the past, essentially, only affected elevator operators or maintenance personnel has, most recently, skyrocketed due to the presence of “elevator surfers,” and, more specifically, due to the determination with which these elevator surfers seek to bypass the safety installation. As a result of this development, safety installations which, until recently, were still deemed satisfactory, have turned out to be inadequate.
A typical safety device is equipped with hatch door contacts on each hatch door which are frequently electronically connected in series, whereby the opening of one single hatch door contact breaks the connection between the power supply and the drive motor. Besides that, additional safety switches exist in the elevator shaft in maintenance-relevant locations, or in locations which pose particular safety problems, namely, specifically, the so-called PES (pit emergency stop), or the pit emergency switch, as well as the TCI (top of car inspection) which is provided on the top of the car and is operated by a mechanic who climbs on top of the car for maintenance purposes. These two switches are frequently also provided in series with the door contact switches. If one of these switches of the safety chain is opened, the connection between the power supply and the drive motor is broken and the elevator car stops in the position it has assumed. Normally, this safety chain is directly connected to the elevator control system. In addition, the PES and the TCI are separately connected to the elevator control system and, apart from that, additional information concerning the current position of the car, etc., is fed to it. The elevator control system software differentiates between the safety chain's signals in their evaluation. Thus, it is quite obvious that, each time the car makes a normal stop on any floor and with every associated opening of the door, the appropriate door safety contact is opened for a short period and the connection between the power supply and the driver is broken. After the door contact has closed, the safety chain is also closed again as a whole, the power supply to the driver is restored, and the elevator can, quite routinely, start on its way to the next destination stop. If, however, the hatch door, e.g., is opened manually when the car is not in a position that is in flush alignment with an opening on a floor, the car, depending upon software control of the equipment, can be taken out of service permanently, and the elevator operator, or a mechanic who might be called, must inspect the equipment and restart its operation.
Although, over the years, this type of safety installation has proved to be reliable, serious and, in some cases, also fatal, accidents have repeatedly occurred, e.g., either when trained personnel did not correctly adhere to the safety instructions because of time pressures or established routine or when unauthorized individuals forced their way into the elevator shaft. For instance, due to the design of the safety chain with series-connected door contact switches, it is possible for elevator surfers manually to open the door one floor above the regular stop location of the elevator car while the subjacent door is open, so that passengers can exit and board, and to close the door again within the same time period. The elevator surfer then stands on top of the elevator car and the elevator safety installation has failed to acknowledge the fact that a second door was opened manually.
An additional typical accident scenario is the following: one of the passengers has dropped a key into the shaft pit through the gap between the car and the landing floor, and the building's elevator operator is called for assistance. He sends the car off from the bottommost landing floor and opens the door on the landing floor with the appropriate unlocking key. Then, he blocks the door on the landing floor with an inappropriate tool (for example, a screwdriver) and climbs into the shaft pit without operating the pit emergency switch that is mounted there. If the screwdriver, which is to serve to secure the door on the landing floor, slips out now, it may happen it will close and the car will begin to move. In such a situation, the typical result is a correction run, i.e., the car will run to one of the end points of its path of movement, that is, all the way to the bottom.
Another situation may occur if a maintenance mechanic wishes to step on the elevator top for maintenance purposes. For this purpose, he calls the car to his landing floor and ensures that there are no passengers inside the car. He then sends the car down far enough that he can easily reach the elevator top, and he opens the door on the landing floor with the corresponding unlocking tool. He then enters the top of the car and, even before he is able operates the top of car emergency switch, he stumbles. In this case, the door on the landing floor also closes and the elevator continues its operation in the usual manner because the safety installation is unable to recognize this dangerous situation.
DISCLOSURE OF INVENTION
In this context, it is the objective of the present invention to configure the safety installation of an elevator in such a way that, as a general rule, the elevator will be taken out of service when unauthorized people enter the elevator shaft.
In accordance with the invention, this objective is realized by means of the fact that the safety installation is equipped with a shaft monitoring device.
It is not mandatory that the shaft monitoring device monitor the entire elevator shaft. For instance, essential partial areas of the elevator shaft to be monitored are the top of the car, on the one hand, and the shaft pit, on the other hand. The shaft monitoring device may, especially preferably, but need not be designed in combination with the mentioned safety installation in the way of a safety chain. Specifically, this type of shaft monitoring device is able to detect an unauthorized entry into the shaft even without the added safety chain, and can take the elevator out of service. Preferably, the shaft monitoring device is equipped with at least one motion sensor. This may either be an ul
Gerwing Axel Steffen
Schoppa Wolfgang M.
Otis Elevator Company
Salata Jonathan
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