METHOD AND SYSTEM FOR MAINTENANCE OF THE DOOR MECHANISM OF AN ELEVATOR SYSTEM

TECHNICAL FIELD

The invention concerns elevator systems for the transport of people or goods between floors or levels of a building, vessel, or other structure, which comprise at least one elevator car or cabin being equipped with doors, and particularly relates to a method and system for determining or monitoring the operating condition of an according door drive mechanism, more particularly of a door drive opener and closer, of such an elevator system.

BACKGROUND

Preventive or predictive maintenance of an elevator door mechanism aims to reduce the degradation of its condition or performance and deterioration of the quality of door operation, caused by environmental effects, use and wear. Environmental factors affecting the condition of the door mechanism can be dust, dirt and temperature. If the elevator doors are not timely serviced or maintained, failure of the doors may result so that the elevator is no longer usable at all or the quality of operation of the elevator decreases decisively, e.g. the doors produce too much noise.

The scheduling of door maintenance is conventionally based either on regular servicing at certain intervals or on the extent of utilization, for example on the cumulative number of times the door has been opened and closed. In US Patent 4,512,442 it is disclosed to count the number of times the doors are opened and closed and to send the revealed number to a maintenance center for scheduling of servicing.

However, known servicing or maintenance methods do not take into account the individual wear of elevators resulting from changing environmental factors and occasional rough treatment. Maintenance and repair of elevators have been scheduled only based on either client notifications about deterioration of elevator condition or on failure reports sent by automatic monitoring systems. Conventional methods of monitoring elevator doors are based on making inferences from events and status. In event-based monitoring, the sequences of occurrence of open, reopened, closed and locked states of the elevator door are monitored using on/off-type signals obtained from sensors, e.g. utilizing open and closed limit switches of the door. By these methods, the need for maintenance can be determined only on a rough level, typically in terms of “either/or” data. A need for maintenance is only determined when elevator operation has stopped completely because of a defective door mechanism.

Further, EP 1 353 868 A1 discloses a method for monitoring the condition of a door mechanism of an elevator system and for determining its need for maintenance. Signals from a control system for the door are measured both in a good operating condition (e.g. shortly after installation of the elevator system) of the door during opening and closing movements of the door. Hereby, a first set of characteristics descriptive of the operation of the door is generated. Accordingly, another set of such characteristics is measured later during normal operation of the elevator system. The two sets of characteristics thus generated are compared with each other and a diagnosis is performed to determine where and how the operation of the door and its components deviates from the operation of the door in the good operating condition. As a result, the need for servicing and a servicing date are established.

From US 10,196,236 B2, a monitoring system of an elevator system and a method of operating the monitoring system are known, by means of which usage data of an elevator door can be generated. The monitoring system includes a sensor for measuring at least one physical parameter of the environment of the sensor. The monitoring system further includes an evaluating unit, which determines an operating state of the elevator door by a course of the physical parameter over time.

In addition, EP 1 922278 B1 discloses a method for improving the performance of an elevator system, wherein the acceleration and/or velocity of the movement of an elevator door and the torque of a door motor moving the elevator door are measured and a dynamic model of the door is created. From an acceleration or velocity being determined based on the model, and from a measured acceleration or velocity, an error function is obtained and its minimum value be determined. In the dynamic model, kinetic parameters of the door are considered. By utilizing the calculated values of the kinetic parameters, the function of the doors is optimized. The kinetic parameters that are used in the optimization of the functions of the elevator door are selected from stored parameters and from an external selection signal, which is either a signal indicating a destination floor or a signal generated by a floor detector moving with an elevator car or cabin.

Furthermore, EP 3403970 A1 discloses a method and system for generating maintenance data of an elevator door system. The method comprises the steps of detecting a first event during closing or opening of a door of the elevator door system and defining a time stamp of the first event, wherein the first event is opening or closing of a safety circuit, detecting at least one second event during said closing or opening of the door of the elevator door system and defining time stamp of the at least one second event, defining a difference value by comparing the time stamp of the first event and the time stamp of the at least one second event, comparing the difference value to previously stored one or more difference values and generating maintenance data of the elevator door system.

SUMMARY

The invention concerns a method and a system for determining and/or monitoring the mechanical and/or electrical functioning/operating condition of an elevator door drive mechanism, in particular of a motorized door opening and closing operator or mechanism, arranged on side of an elevator car or cabin and/or on side of a corresponding door mechanism arranged at a floor of an underlying building. The monitoring shall include the checking of a proper opening and closing operation of an elevator door, and is particularly aimed at providing the capability of predictive and/or remote maintenance of such a door mechanism in order to determine its need for maintenance.

Known elevator systems are already equipped with a remote maintenance capability, which enables mobile communication. Therefore, a technician can check and diagnose the functionality of the elevator, for example by mobile phone, and can determine which tasks of the maintenance process are necessary to perform. However, some maintenance aspects or processes of an elevator are yet to be implemented in such a remote maintenance system, like the process of reliably monitoring the (electro-) mechanical condition of an elevator door mechanism, in particular of a mentioned door opener/closer respectively.

More particularly, the process of checking the door opener/closer is not yet supported by the currently known remote maintenance systems. These systems only monitor the timing of a door, but the actual driving force of a motor drive for moving the door is more important in order to prove a safe door operation. The faultless functioning of this component is important to ensure that an elevator door closes smoothly and quietly.

The necessity of an according maintenance process can be fulfilled by the solution presented herein thus making remotely performed maintenance of elevator doors more efficient and/or to help to improve the operative efficiency of maintenance personnel or workers.

The underlying idea of the proposed method is to measure electrical current of the door motor during an opening operation and a closing operation. If the difference between these two current values decreases below an empirically determined threshold value then it is concluded that the door opener/closer is degraded or even broken or inoperable. The idea is based on the present experience or knowledge that the mechanical or operating condition of the mentioned part of an elevator door drive over time may be damaged by wear or that these parts may change their mounting position or may lose their tightness, in particular due to the rather frequent opening and closing events or processes even during normal operation of an underlying elevator system.

It has to be mentioned that the mentioned electrical (motor) current values can be determined reliably, based on an existing or dedicated elevator control system. Hereby, existing operating data concerning door-operation-dependent motor drive currents needed for operating the motor drive of the doors, or existing sensors for monitoring the opening and closing of doors, can be utilized.

According to another aspect of the proposed method, the results of the mentioned evaluation of the difference between the two current values can be correlated with at least another physical property which is relevant for door operation or the use condition or electromechanical state of a door mechanism, e.g. the time that has passed since the last maintenance service and/or the total number of door operations. By this correlation, the reliability of the proposed method can be enhanced significantly.

Further proposed is a system or control system for checking and/or monitoring the condition of an elevator door mechanism, in particular of a mentioned door opener/closer, which comprises a data storage in order to allow the mentioned evaluation of measured or determined electric current values to be accomplished by a comparator, or according evaluation unit. The comparator or evaluation unit compares actual difference values of the electrical current for opening and for closing a door of an underlying elevator system with a corresponding, empirically (pre-)determined threshold value and evaluates the necessity of a maintenance service for a respective elevator door.

The system or control system may further include a communication unit, which, in case of the actual current difference value lying below the given threshold, automatically sends a corresponding maintenance request to a stationary or portable communication or computer device of a service engineer, like a server computer or desktop PC, smart phone or tablet PC. Alternatively, the communication unit can change a priority bit or value for a maintenance service call, based on the evaluation result.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects, features and advantages of the invention are understood within the context of the Detailed Description, as set forth below. The Detailed Description is understood within the context of the accompanying drawings, which form a material part of this disclosure, wherein:

FIG. 1 shows an embodiment of the elevator control system according to the invention, by way of a block diagram.

FIG. 2 shows an embodiment of the method according to the invention, by way of a flow diagram.

DETAILED DESCRIPTION

The elevator system schematically shown in FIG. 1 includes an elevator cabin 100 arranged in an elevator shaft 105. The elevator cabin 100 is depicted in a front view in order to better illustrate an underlying elevator car door mechanism including two elevator doors 110, 115 in the present embodiment. Of course, the present invention can also be applied to an elevator system or corresponding door drive mechanism for operating only one door or even more than two doors. In addition or alternatively, the present invention can also be applied to a door drive mechanism or operator being arranged at each of the floors of an underlying building.

The operation of the shown door drive mechanism for operating the two elevator doors 110, 115, is controlled by an elevator control unit 120, which in the present embodiment is arranged on side of the shown elevator cabin 100. However, the control unit 120 can also be arranged at a wall of the elevator shaft 105, or a main control room residing e.g. on the top of the shaft 105. The control unit is connected to two electrical motor drives 125, 130 via respective control or communication lines 135, 136. The communication lines 135, 136 serve for the provision or transmission of actual electric current values from the two electrical motor drives 125, 130 to the elevator control unit 120. The electrical motor drives 125, 130, as part of the mentioned door drive mechanism or operator, serve for the opening and closing movements of the elevator doors 110, 115.

The communication lines 135, 136 shown, as indicated by the dotted lines, can be implemented either using known wired or wireless communication technologies. The control unit 120, as depicted in its enlarged view right-hand, according to its present function as an evaluation unit, includes a local data storage 160 in which detected or measured electric current values for opening and for closing of each of the two elevator doors 110, 115 are stored. In addition, the control unit 120 includes a digital comparator 165, which compares the difference of electric current values recently stored in the data storage 160 with a predetermined, e.g. previously and empirically determined, threshold value 170. The comparator 165, in particular, checks whether the difference between these two current values decreases below the threshold value 170. If this is the case, then it is concluded that the respective electrical motor drive 125, 130 of the door opener/closer is degraded or even broken or inoperable.

The output signal or information 175 delivered by the comparator 165 is utilized after that to increase the priority for planning of the maintenance of the door drive mechanism or to trigger an according maintenance service, which is accomplished in the control unit 120 in the present embodiment.

In a further embodiment, the comparator 165 can compare an electrical current difference value with two or even more existing threshold values, wherein each of these threshold values relates e.g. to a specific priority level for planning the maintenance. Hereby, the planning of the maintenance can be implemented much more easily, or with much lower implementation and cost efforts, respectively.

The control unit 120 of the elevator system shown in FIG. 1 is connected with a (herein not shown) remote maintenance center by means of a communication unit 180. The transmission 185 of the information 175 delivered by the control unit 120 to the remote maintenance center is effected using known transmission protocols based on a telephone line or any wired or wireless connection.

When information is sent from the control unit 120 to the remote maintenance center for analysis of such information, the data can be transmitted e.g. in connection with a test call on an emergency telephone line. Since the information 175 is transmitted 185 only when the described difference values are below a mentioned threshold limit, according data traffic is saved considerably.

It has to be mentioned that, according to an alternative embodiment, the evaluation of the measured electric current values can also be accomplished on the side of the (not shown) remote maintenance center. In such an embodiment, the evaluation unit 120 and its comparator have to be arranged on side of the maintenance center in order to perform the described data comparisons with corresponding threshold values. Therefore, in such an embodiment, the control unit 120 can be a common control unit as known in the art, which then only transmits measured or gathered electric current values on a temporal basis to the remote maintenance center, which evaluates the transmitted current values on site.

Based on the results of the evaluation of the electric current values, the need for maintenance is determined, either on side of the elevator system or on side of the remote maintenance center. Based on the determined need for maintenance, a servicing date, i.e. a date by which the doors of the underlying elevator system should be serviced, is determined. This prevents malfunctions and guarantees an acceptable level of performance and safety of the elevator system.

The determined servicing date can also be compared with a preliminary servicing visit schedule stored in a database arranged on side of the remote maintenance center. If necessary, an earlier date is assigned for a scheduled servicing visit. For the servicing visit, instructions regarding the relevant doors are generated from the evaluation results, as to which parts of the door mechanism need servicing.

In the procedure shown in FIG. 2 it is assumed that after an opening or closing operation of the two doors 110, 115 depicted in FIG. 1 always an opposite movement of the doors 110, 115 occurs, namely a closing or opening operation. According to the shown procedure, it is therefore first checked or detected 200 whether an opening or a closing operation occurred. This distinction can be made e.g. by the control unit 120 shown in FIG. 1 or by means of an additional sensor system, e.g. a sensor being used for checking whether the doors are already closed completely before the elevator car or cabin is set in motion.

It has to be mentioned hereby that the electrical current signals transmitted via the communication lines 135, 136 shown in FIG. 1 are gathered either continuously or only during a pending door movement operation. According to the latter option, the control unit 120 depicted in FIG. 1 can trigger the gathering of the according data only when a door movement occurs, so that the total amount of gathered data is limited considerably.

In the now assumed case of e.g. a detected opening operation of the two doors 110, 115, in the next step 205 the corresponding two electrical currents of the electrical motor drives 125, 130 of the two doors 110, 115 during the opening movement are gathered from the two electrical motor drives 125, 130, or be provided by the control unit 120. The gathered two electric current values are then (digitized and) stored 210 at least temporarily.

In step 215 it is further checked whether there have been gathered at least two electrical current data or values, namely for the opening and for the closing door operation. If the recently stored data only related to one of these two operation modes, then the procedure jumps back to the beginning, i.e. to step 200. Otherwise, if the recently stored data cover both the opening and the closing operation, then the procedure continues with step 220 where for these two data or values a difference value is calculated or determined.

In the further checking step 225, the calculated difference value or data is compared with an empirically predetermined threshold value 230. If the comparison 225 reveals that the difference value does not fall below the threshold value 230, it is jumped back to the beginning of the procedure, namely before step 200.

Otherwise, if the difference value falls below the threshold value 230, then it is concluded 235 that the underlying electrical motor drive 125 or 130 is degraded or even broken or inoperable. As a consequence, a higher priority of the maintenance plan for the underlying elevator system and/or for the underlying door drive mechanism is set.

According to the following optional (dotted line) step 240, the concluded 235 degradation results can either be output to a local service technician via an in-car display of the underlying elevator system or be transmitted to a remote maintenance center, as already described in connection with FIG. 1.