Patent Application
20080230326
The present invention relates to elevator systems. In particular, the present invention relates to a system for monitoring the operational condition of elevators.
An elevator system is an electromechanical assembly of equipment that contains many movable and rotating parts, which are subjected to wear and failures during the operation of the elevator system. Also, the actuators controlling the movable and rotating parts as well as the electric components and sensors connected to the said actuators are subjected to wear and failures in long-time operation of the elevator system. A failure may also be caused by unexpected external factors, such as e.g. a violent impact against the elevator door or as a result of vandalism perpetrated on the elevator. However, it is of primary importance for the operation of elevator systems that the elevator system should work correctly and above all safely in all operational conditions. Therefore, elevator systems are serviced regularly to guarantee safe operation and sufficient riding comfort. If the elevator is not serviced in time, the elevator may fail so that either passengers can not use the elevator at all or the quality of operation of the elevator deteriorates significantly. Before an actual failure, the elevator may become noisy, there may appear unpleasant vibrations of the elevator car, the stopping accuracy of the elevator car at landings may deteriorate or some other corresponding feature of the operation of the elevator may be impaired, indicating a future failure in advance. The scheduling of maintenance of elevators has traditionally been implemented either via regular maintenance according to a fixed calendar-based schedule and/or on the basis of the intensity of operation (operating history) of the elevator. The intensity of operation again depends on the place of installation of the elevator, causing individual needs regarding maintenance arrangements. If a need for maintenance is not detected until one of the actuators controlling the operation of the elevator suddenly fails and prevents preparation of the elevator, this may result in a service advice made by the client, causing extra expenses to the party responsible for the operation of the elevator. One method of eliminating or at least reducing the number of unscheduled maintenance visits is to provide the elevator with a condition monitoring system. The function of a condition monitoring system is to observe the operation of the elevator and to generate parameters representing its operational condition, on the basis of which it is possible to estimate the current operational condition of the elevator and to predict its future operational condition to enable mapping of the need for preventive maintenance. The condition monitoring system generally connects to signals indicative of the operation of the elevator, on the basis of which the system calculates parameters descriptive of the operational condition of the elevator. A sufficiently large deviation or trend of change of a parameter in relation to defined reference values produces a particular alarm about an acute or anticipated failure. The alarm information is often transmitted from the condition monitoring system to a maintenance center responsible for the maintenance of the elevator system, where the decisions regarding the required maintenance operations and their scheduling are made. For example, the systems disclosed in patent U.S. Pat. No. 4,512,442 Moore et al. keep count of how many times the doors have been opened and closed and send the count to a maintenance center for maintenance scheduling. Scheduling based on intensity of operation can be made more accurate by taking the type of the building into account. Certain more advanced prior-art systems additionally use operating history data of elevators for condition monitoring.
Prior-art condition monitoring systems have considerable drawbacks and deficiencies. The signals indicative of the operation of the elevator are often difficult to obtain, which is why installing and connecting the condition monitoring system to the elevator system is difficult and time-consuming. Some of the signals needed in condition monitoring may be located at a long distance from each other, for example in a control panel in the elevator machine room while some other signals are located in the elevator car. In this case it is necessary to have an extra car cable between the elevator car and the machine room to provide the wiring for the required signals to the condition monitoring system, involving a sharp increase in installation costs and time. In prior-art solutions, making a connection to the signals to be measured generally requires a galvanic connection between the condition monitoring system and the elevator control system, and often also changes in the cabling of the elevator, causing unnecessary installation work and extra costs. The galvanic connection method involves the risk of causing interference with the operation of the elevator system signals used for condition monitoring, thus producing a safety hazard. For this reason, an elevator often has to be subjected for approval by authorities supervising elevator safety to check the operation of the safety equipment after the installation of a condition monitoring system.
A further problem with prior-art solutions is that elevator systems differ significantly from each other in both electrical and functional respects. The condition monitoring system has to take into account, among other things, the current and voltage levels of the signals used in the elevator to be monitored, the timing of the signals and other elevator-specific circumstances. Condition monitoring systems implemented according to prior-art technology are therefore generally applicable only in connection with certain elevator types, but installing them in old elevators may be impossible or the required installation, modification and configuration work may become a significant cost factor.
The object of the present invention is to overcome some of the above-described drawbacks and deficiencies encountered in prior-art solutions and to achieve a completely new type of solution for monitoring the condition of an elevator. An additional object of the invention is to achieve one or more of the following aims:
The condition monitoring system of the invention is characterized by what is disclosed in the characterization part of claim 1. Other embodiments of the invention are characterized by what is disclosed in the other claims. Inventive embodiments are also presented in the description part and drawings of the present application. The inventive content disclosed in the application can also be defined in other ways than is done in the claims below. The inventive content may also consist of several separate inventions, especially if the invention is considered in the light of explicit or implicit sub-tasks or in respect of advantages or sets of advantages achieved. In this case, some of the attributes contained in the claims below may be superfluous from the point of view of separate inventive concepts. Within the framework of the basic concept of the invention, features of different embodiments of the invention can be applied in conjunction with other embodiments.
Below are definitions of the meaning of some terms used in the text:
The invention concerns an elevator condition monitoring system which comprises at least a control unit and a sensor arrangement connected to the control unit. The elevator comprises an elevator car, an elevator drive machine and a control system, including the required safety circuit and actuators. According to the invention, the control unit of the condition monitoring system and the sensor arrangement connected to the control unit are fitted in conjunction with the elevator car, and the said sensor arrangement comprises at least a sensor measuring the current of the elevator safety circuit, said sensor being galvanically separated from the elevator safety circuit and connected to the safety circuit without interrupting the safety circuit wiring. The control unit and the sensor arrangement are preferably fitted on the top of the elevator car.
In an embodiment of the invention, in addition to the sensor measuring the safety circuit current, the sensor arrangement connected to the control system comprises one or more of the following sensors:
In an embodiment of the invention, the condition monitoring system produces one or more of the following derived quantities:
In an embodiment of the invention, utilizing derived quantities, the condition monitoring system determines one or more result quantities, which indicate:
In an embodiment of the invention, the condition monitoring system comprises a memory device for the storage of derived quantities and/or result quantities for later use.
In an embodiment of the invention, the condition monitoring system comprises a data transfer connection for the transmission of derived quantities and/or result quantities and/or alarms indicative of the operational condition of the elevator to a remote monitoring system.
In an embodiment of the invention, the condition monitoring system has been fitted to send information stored on the memory device to the remote monitoring system at predetermined points of time.
In an embodiment of the invention, the condition monitoring system comprises a memory device with one or more derived quantity threshold values stored on it for the detection of failure situations and/or a need for preventive maintenance.
In an embodiment of the invention, one or more threshold values and/or setting parameters have been determined by performing at least one test run of the elevator.
In an embodiment of the invention, the condition monitoring system has been fitted to determine threshold values and/or setting parameters on the basis of statistical and/or other corresponding analyses.
The condition monitoring system of the present invention has several advantages as compared to prior-art solutions. The condition monitoring system is easy and quick to install, because its control unit and the sensors connected to it are placed in conjunction with the elevator car. To connect the sensors, no extra car cable is needed between the elevator car and the elevator control system. The sensors required in condition monitoring are also easy to install as retrofits in conjunction with the elevator car because their placement in conjunction with the elevator car is nearly freely selectable and the existing cabling of the elevator car need not necessarily be modified. As it uses sensors galvanically separated from the control unit of the elevator system, the system of the invention causes no safety risk in the operation of the elevator system. Especially making a connection to the safety circuit of the elevator system involves no problems because the connection does not form a galvanic connection between the condition monitoring system and the elevator safety circuit and it does not require interruption of the safety circuit (e.g. disconnection of a safety circuit conductor from a connector), and therefore also extra inspections by authorities after installation of the system are avoided. To allow faster installation, configuration of the system can be executed automatically. Using the system of the invention, it is also possible to collect information about the use of the elevator system and to measure the performance of the elevator system. The data produced by the system can be transferred to a remote maintenance system for the preparation of statistical and other corresponding analyses concerning e.g. the operational condition, use and/or performance of the elevator system.
In
By determining the states of the safety circuit in the above-described manner in different operating situations of the elevator, the condition monitoring system is able to determine the operational condition of the elevator safety circuit and of the actuators influencing the state of the safety circuit.
The car door, the landing doors and the door operator mounted on the car form a door mechanism, the condition of which is monitored by means of an acceleration sensor attached to a car door leaf to measure the acceleration adoor of the horizontal motion of the door leaf. To obtain a more accurate determination of the operational condition of the door mechanism, it is also possible to measure door leaf accelerations perpendicular to the aforesaid motion. The acceleration adoor is used as a means of observing the motion components of the door leaf during a door operation, such as e.g. instantaneous acceleration, speed, position and/or vibration spectrum of the door leaf. From the door leaf motion components, it is further possible to infer door status data (states and their mutual timing). Possible door states are: closed, opening, opened, closing, reopening, nudging. In the solution illustrated in
For monitoring of the condition of the elevator drive machine, the elevator is provided with an acceleration sensor 62 mounted on the car to measure the vertical acceleration acar of the elevator car. To obtain a more accurate determination of the operational condition, it is also possible to measure car accelerations perpendicular to the vertical motion. Vertical motion components of the elevator car, such as e.g. instantaneous acceleration, speed, location in the elevator shaft and/or vibration spectrum, are calculated from the acceleration acar by known mathematical methods. From the car motion components, it is further possible to infer car status data. The car status may be one of the following: standing, accelerating, constant speed, decelerating, creeping, releveling. Changes in the motion components and/or status data of the elevator car indicate wear, soiling and/or an electrical or mechanical fault of the drive machine. The condition of the drive machine can also be monitored by means of a microphone 264 mounted on the elevator car by analyzing the frequency spectrum of the noise Ncar produced during the various stages of operation of the elevator. An increase in the amplitude of the noise at the frequencies considered indicates changes, such as e.g. wear, taking place in the drive machine.
The condition of the drive machine can also be monitored by means of a door zone sensor 266 mounted on the elevator car. The sensor detects the entry and exit of a reference mounted at each floor level into/from the detection field of the sensor as the elevator is moving in the elevator shaft. By combining the door zone reference detection data Pdzone and the location data derived from the acceleration acar of the elevator car, it is possible to determine the exact stopping distance of the elevator car relative to the edge of the reference detected and thus to monitor the stopping accuracy of the elevator car at different landings. Variation in the stopping accuracy of the car indicates changes in the elevator drive machine, such as e.g. in the brake of the drive machine.
In
To monitor the illumination of the elevator car, the condition monitoring system measures the current Ilight consumed by the lighting by means of a current sensor 264. When the lighting current is reduced in relation to the reference value of the current, it is possible to infer the number of defective light sources. If the current becomes pulsating, this indicates a future failure of a light source.
Besides the above-described data associated with condition monitoring of the elevator, the system also produces information relating to the use and performance of the elevator. Utilizing the measured signals and the status data derived from the signals, it is possible to determine the times of activity of the various actuators comprised in the elevator as well as the numbers of actions, such as e.g. the number of door operations, duration of the stages of door operations, the number of departures and stops of the elevator at each floor, traveling times of the elevator between different floors. Thus, the system can produce information for the calculation of the performance and operating history of the elevator.
The data collected on the memory device 210 is transferred from the control unit to the remote monitoring system 105 over the data transfer connection 106 in periods of defined time intervals. The data received in the remote monitoring system is stored in a database 271, where the data can be further used for statistical analyses, calculation of operating intensity of the elevator (operating history of the elevator) and/or performance of the elevator.
The sensor arrangement 250 consists of a number of sensors, one or more of which are galvanically separated from the elevator control system. The elevator car has to be retrofitted with sensors unless it is already provided with sensors ready for connection to the remote monitoring system. ‘Sensor’ also refers to measuring points (e.g. connectors) which already exist in conjunction with the elevator car and to which the condition monitoring system can be connected directly by conductors. In such cases, the sensor producing the signal to be measured may also be located elsewhere in the elevator system than on the elevator car, where the sensor signal has already been wired as an implementation comprised in the elevator system. The current sensors used for the current measurement are e.g. ferrite core sensors based on induction, the core structure of which can be opened so as to allow threading of the current conductor to be monitored into the passage formed by the sensor core without breaking the conductor. In conjunction with these sensors it is advantageous to compensate the frequency response and/or temperature creep of the sensor by using a suitable compensating connection to improvemeasured acceleration ad the measuring accuracy. For detection of the door zone reference, the elevator car is provided with an proximity sensor 266, which may be any contactless proximity sensor suited for the purpose, such as e.g. an inductive, optical or capacitive proximity sensor. The proximity sensor identifies the reference mounted at each landing, e.g. bar-like object made of magnetic material or a luminescent elongated sticker.
To determine the threshold values and setting parameters used by the condition monitoring system, one or more test runs are performed on the elevator after the installation of the system. Based on the information collected during the test runs, the condition monitoring system determines at least some of the threshold values and/or setting parameter values automatically. During operation of the elevator system, the condition monitoring system collects data about the elevator system and updates the aforesaid values by known statistical methods. Thus, the condition monitoring system is self-learning and is able to automatically adapt itself to changing conditions.
In the case of an elevator system with a multi-deck elevator, wherein two or more elevator cars have been fitted in the same car frame, one or more condition monitoring systems are installed to monitor the operational condition of the elevator in question.
It is obvious to the person skilled in the art that the invention is not limited to the embodiments described above, in which the invention has been described by way of example, but that different embodiments of the invention are possible within the scope of the inventive concept defined in the claims presented below.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20050361 | Apr 2005 | FI | national |
| 20060277 | Mar 2006 | FI | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/FI06/00106 | Apr 2006 | US |
| Child | 11902354 | US |
