Elevator – industrial lift truck – or stationary lift for vehicle – With monitoring – signalling – and indicating means – Monitors operational parameter
Reexamination Certificate
2002-05-02
2003-07-15
Salata, Jonathan (Department: 2837)
Elevator, industrial lift truck, or stationary lift for vehicle
With monitoring, signalling, and indicating means
Monitors operational parameter
C187S247000, C187S316000, C198S323000
Reexamination Certificate
active
06591947
ABSTRACT:
FIELD OF THE INVENTION
The invention pertains to a transport system, in particular, a passenger transport system, such as an elevator, a moving sidewalk, or an escalator, where said transport system is provided with a controller, a drive motor, and a safety switch that is able to distinguish between a safe state of the transport system and an unsafe state of the transport system and that is connected to the controller in order to interrupt the power supply to the drive motor in the unsafe state.
BACKGROUND OF THE INVENTION
Transport systems of this type are broadly utilized in the form of elevators, as well as in the form of escalators and moving sidewalks. The safety switch serves for monitoring safety-related states of the corresponding transport system. In elevator systems, for example, the elevator shaft doors and, if applicable, the elevator car doors are continuously monitored. When one of the doors is opened, the controller interrupts the power to the drive motor until the door, and thus the safety switch, are correctly closed again and power to the drive motor is restored. The doors of elevator systems require considerable maintenance. For example, the elevator shaft doors are typically suspended from suspension mechanisms on which rollers are mounted in corresponding guide rails, which are accommodated in the lintel beam over the shaft door opening. The door may comprise one or more door panels. There are door designs with centrally opening shaft doors and laterally opening shaft doors, as well as those in which several door panels open and close in telescoping fashion in only one direction. The drive of the shaft doors is realized, e.g., by means of a drive cable or drive belt that is also arranged in the lintel beam over the shaft door opening. The shaft doors must be correctly adjusted in order to ensure the reliable opening and closing of the doors. Elevator car doors are similarly arranged on elevator cars.
Currently, two-part safety contacts are used in elevator doors, where one part contains two openings that lie closely adjacent and the other part essentially consists of a U-shaped metal profile, which, when the door is correctly closed, protrudes into the two openings of the other part and closes the contact between two electrical connections therein. Here, the two parts of the safety switch are arranged on door panels that open and close relative to one another, particularly in a region above the lintel.
Alternatively, one part of the safety contact is arranged on an opening door panel in laterally opening doors, where the other part is arranged, for example, on the door frame or the door frame soffit. The door switch is adjusted in such a way that the contact is closed when the door is correctly closed. The door switch requires adjustments in order to ensure that the contact is no longer closed once there exist a certain gap, for example, between the two door panels. When this condition occurs, the power to the drive motor is interrupted and operation of the elevator system can only resume if the elevator doors are readjusted and correctly close again.
The customary wear associated with the operation as well as the use of force on the elevator door, e.g., due to forcefully opening the door, etc., causes the door no longer correctly to close. In both instances, the incorrectly or unsafely closed condition does not occur from one instant to the next, but the transition from a correctly to an incorrectly closed condition takes place gradually. Conventional safety switches are unable to detect this gradual deterioration. The safety switch is only able to detect such deterioration once a certain wear or misalignment condition appears. In such circumstances, the elevator system is deactivated from one instant to the next. Such sudden shutdowns of elevator systems are undesirable for several reasons. First, the operators of elevator systems are always unhappy if the elevator system suddenly shuts down and maintenance must be called to restore service. Second, high expenditures with respect to personnel and logistics are needed to ensure that those elevator systems requiring service can be repaired around the clock.
The situation is quite similar with respect to escalators or moving sidewalks. These passenger transport systems typically contain a so-called step band that consists of a series of interconnected step elements, i.e., stairstep or pallet elements, which are moved from an entry point to an exit point by a drive motor. So-called bottom paneling is provided to the side of the step elements or pallet elements. The gap between the step elements and the bottom paneling must be maintained within a relatively narrow range for safety reasons. This is usually also monitored with corresponding safety switches. These safety switches typically trigger when the gap is exceeded and cause the escalator or moving sidewalk to be deactivated in such cases. In principle, the negative effects of these undesirable shutdowns are identical to those described above with reference to elevator systems.
SUMMARY OF THE INVENTION
The present invention is based on the objective of making available transport systems of the initially mentioned type which fulfill the corresponding safety requirements and significantly minimize the risk of a sudden shutdown when an unsafe state is detected.
According to the invention, this objective is realized in that the safety switch is effected so that it is able also to detect a warning state in addition to the safe and unsafe states.
The invention makes it possible to detect a warning state before an unsafe state is reached. Consequently, it is possible to indicate this warning state via the safety control. A corresponding warning message may be directly sent to maintenance, e.g., via a remote line. An arbitrary display device may alternatively or additionally inform the building's elevator attendant who then contacts maintenance. The transport system may be adjusted in such a way that, during typical operation, the warning state is indicated, for example, at least fourteen days before an unsafe state occurs. This means that sufficient time remains for readjusting the system or exchanging the defective parts during planned maintenance procedures. It would also be possible to realize the safety switch such that it continuously indicates the state of wear of the system instead of merely indicating a warning state once a certain intermediate state is reached.
Naturally, it is also possible to detect several intermediate states that essentially correspond to different warning levels. The safety switch preferably consists of a proximity switch, where an inductive proximity switch is particularly preferred. Alternatively, capacitive switches or devices may be used which, for example, determine the relevant spacing between two parts with the aid of light, ultrasound, etc.
Generally speaking, safety switches that cannot be manipulated are particularly preferred. For example, simple distance measuring devices that operate with ultrasound or light have the disadvantage that a closed door can be simulated with a mirror or another object. This is the reason why inductive proximity switches, particularly those composed of two parts are provided. In this case, the “passive part” preferably consists of a magnetic material, e.g., ferrite, with a certain magnetic field strength, to which the sensor part is “calibrated.” This type of switch design is difficult to manipulate with any given magnet. This feature is particularly important because elevator surfers increasingly attempt to bypass the safety devices in elevator systems in order to ride on the roof of the elevator car.
The safety switch is preferably realized in such a way that it outputs a certain non-zero value of the output variable, e.g., the voltage, the current, the resistance, etc. When using a switch that does not deliver three discrete values, but rather is able to generate individual or continuous intermediate values, a continuous range of values which should not include zero is corresponding
Herkel Peter
Horbrügger Herbert
Spannhake Stefan
Otis Elevator Company
Salata Jonathan
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