Patent Application
20190248625
The invention concerns in general the technical field of an elevator technology. Especially, the invention concerns solutions for preventive maintenance of an elevator movement sensor system.
An elevator comprises typically an elevator car and a hoisting machine configured to drive the elevator car in an elevator shaft between the door zones. For safety reasons the vertical position of the elevator car inside the elevator shaft in relation to the door zones, i.e. absolute positioning, may be needed to be defined under certain conditions. In some circumstances the absolute position information may need to be known with an accuracy of approximately 10 mm. Examples of that kind of conditions may be elevators having reduced stroke buffers or in elevators used in a certain geographical location. Furthermore, the absolute positioning may be useful when implementing some safety functions of an elevator. In order to enhance the safety of an elevator system, the absolute positioning may be implemented to be independent from a drive control system of the elevator.
Preferably, the absolute positioning may be implemented by means of a component that fulfills the accuracy requirements. A Safety Integrity Level (SIL) may be used to indicate a tolerable failure rate of a particular safety function, for example a safety component. SIL is defined as a relative level of risk-reduction provided by the safety function, or to specify a target level of risk reduction. SIL has a number scheme from 1 to 4 to represent its levels. The higher the SIL level is, the greater the impact of a failure is and the lower the failure rate that is acceptable is.
Accordingly, there is a need to ensure operating condition of the absolute positioning solutions in an elevator system.
An objective of the invention is to monitor operating condition of the elevator speed sensor system to ensure continuous operation without elevator service interruptions.
A first aspect of the invention is a method for preventive maintenance of an elevator speed sensor system comprising at least a first and a second sensor, which are independent of each other, the method comprising: determining a reference distance for an elevator car travel between a first door zone and a second door zone. During an elevator car travel between a first door zone and a second door zone, defining continuously a first elevator car speed information from the first sensor and a second elevator car speed information from the second sensor, calculating a cumulative sensor system error by integrating the difference between the first elevator car speed information and the second elevator car speed information, dividing the cumulative sensor system error with the reference distance to obtain a sensor system performance indicator.
This can mean that operating condition of a speed sensor system (which preferably also acts as an absolute positioning sensor system of an elevator) can be monitored and maintenance can be performed to calibrate or repair the sensor system before it fails. A defective absolute positioning sensor system would mean that elevator has to be taken out of service, thus causing service interruption and therefore discomfort to elevator passengers.
A second aspect of the invention is an elevator system comprising an elevator car, a hoisting machine with a hoisting motor to drive the elevator car and a speed sensor system comprising at least a first sensor and a second sensor for measuring movement of the elevator car. The elevator system further comprises: an elevator control apparatus, which elevator control apparatus is connected to the first sensor and the second sensor, and which elevator control apparatus has a remote connection interface to the maintenance server. The elevator control apparatus is configured to perform a method according to the first aspect of the invention for preventive maintenance of the elevator system.
According to an embodiment of the first aspect of the invention: obtaining supply frequency of elevator hoisting motor during the elevator car travel continuously from motor controller of the elevator hoisting machine and defining a third elevator car speed information therefrom, comparing the first elevator car speed information and the second elevator car speed information with the third elevator car speed information, and based on the comparison, adding a sensor identification to the sensor system performance indicator. This can mean that the particular sensor needing maintenance (for example calibration or moderate repair work) may be identified and the established service request may include identification of this sensor, thereby facilitating the maintenance work.
According to an embodiment of the first aspect of the invention: transmitting the sensor system performance indicator to a maintenance server, in the maintenance server, establishing a service request based on a sensor system performance indicator or on a sequence of sensor system performance indicators, the service request being established before the speed sensor system is considered as defective, and transmitting the service request to a maintenance service unit.
According to an embodiment of the first aspect of the invention: calculating statistics information from a set of performance indicators, transmitting the statistics information to a maintenance server, in the maintenance server, establishing a service request based on the statistics information, the service request being established before the speed sensor system is considered as defective, and transmitting the service request to a maintenance service unit. This can mean that statistics information can be generated on elevator site and transmitted to a maintenance server only periodically, thus reducing data transfer between elevator and maintenance server. Further, it is possible to use several consecutive pieces of statistics information to detect trend(s) in sensor system operating condition, which improves sensor system diagnostics and helps in scheduling the service requests.
According to an embodiment of the first aspect of the invention, the first sensor is a first pulse sensor unit providing a pulse position information of the traction sheave of the hoisting machine of the elevator car, the first pulse sensor unit comprising: at least one magnetic sensor measuring magnetic field variation from a rotating magnet ring arranged in the traction sheave of the hoisting machine.
According to an embodiment of the first aspect of the invention, the second sensor is a second pulse sensor unit providing a pulse position information of the elevator car, the second pulse sensor unit comprising: at least one quadrature sensor measuring incremental pulses from a rotating magnet ring arranged in an overspeed governor arranged in the elevator shaft.
According to an embodiment of the first aspect of the invention, the floor number, identification code, magnet type, and the linear position of the elevator car within the door zone is obtained from at least one door zone sensor unit comprising at least one Hall sensor and a RFID reader.
According to an embodiment of the first aspect of the invention, calculating a reference distance for an elevator car travel between a first door zone and a second door zone comprises: obtaining and storing a pre-information about at least one door zone magnet at a door zone of each floor of an elevator shaft during a setup run, the pre-information comprising the following: floor number, identification code, magnet type, pulse position information, linear position information, and calculating the reference distance between the door zones by using the pre-information.
The exemplary embodiments of the invention presented in this patent application are not to be interpreted to pose limitations to the applicability of the appended claims. The verb “to comprise” is used in this patent application as an open limitation that does not exclude the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated.
The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objectives and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
The embodiments of the invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings.
Furthermore, the elevator system 100 comprises at least one door zone magnet 114a-114n at a door zone of each floor of the elevator shaft. The at least one door zone magnet 114a-114n is fixed to the elevator shaft. Preferably, the at least one magnet 114a-114n may be fixed to a landing door frame in the elevator shaft. The door zone may be defined as a zone extending from a lower limit below floor level 116a-116n to an upper limit above the floor level 116a-116n in which the landing and car door equipment are in mesh and operable. The door zone may be determined to be from −400 mm to +400 mm for example. Preferably, the door zone may be from −150 mm to +150 mm. Alternatively or in addition, the elevator system 100 according to the invention may comprise at least one terminal magnet at least at one terminal floor of the elevator shaft. The at least one terminal floor may be the top or the bottom floor. Each magnet may comprise at least one passive RFID tag. The at least one RFID tag comprises unique identification code (UID) and type code of the magnet.
Additionally, for safety reasons elevator system may comprise an overspeed governor (OSG) 112 arranged in the elevator shaft to stop the movement of the elevator car 102, if the elevator car 102 speed meets a predefined speed limit. The OSG 112 may comprise a sheave 113 rotated by a governor rope (not shown in
A schematic example of the safety control unit 104 according to the invention is disclosed in
The processor 402 of the safety control unit 104 is at least configured to implement at least some method steps as described. The implementation of the method may be achieved by arranging the at least one processor 402 to execute at least some portion of computer program code 405a-405n stored in the memory 404 causing the one processor 402, and thus the safety control unit 104, to implement one or more method steps as described. The processor 402 is thus arranged to access the memory 404 and retrieve and store any information therefrom and thereto. For sake of clarity, the processor 402 herein refers to any unit suitable for processing information and control the operation of the safety control unit 104, among other tasks. The operations may also be implemented with a microcontroller solution with embedded software. Similarly, the memory 404 is not limited to a certain type of memory only, but any memory type suitable for storing the described pieces of information may be applied in the context of the present invention.
As described the pulse position information of the elevator car 102 may be obtained from the pulse sensor unit 108. A schematic example of the pulse sensor unit 108 according to the invention is disclosed in
The processor 501 of the pulse sensor unit 108 is at least configured to obtain the quadrature signal from the at least one quadrature sensor, define the pulse position information based on the quadrature signals and to store the defined pulse position information into the memory 503. The processor 502 is thus arranged to access the memory 504 and retrieve and store any information therefrom and thereto. For sake of clarity, the processor 501 herein refers to any unit suitable for processing information and control the operation of the pulse sensor unit 108, among other tasks. The operations may also be implemented with a microcontroller solution with embedded software. Similarly, the memory 503 is not limited to a certain type of memory only, but any memory type suitable for storing the described pieces of information may be applied in the context of the present invention. The pulse sensor unit 108 may be a separate unit communicatively coupled to the safety control unit 104. Alternatively, the pulse sensor unit 108 may be implemented as part of the safety control unit 104 or the pulse sensor unit may be implemented as an additional circuit board operating as an interface between the at least one quadrature sensor 504 and the safety control unit 104.
As described at least the linear position information of the elevator car 102 may be obtained from at least one door zone sensor unit 106. Preferably, one door zone sensor unit 106 may be provided for each elevator car door. A schematic example of the at least one door zone sensor unit 106 according to the invention is disclosed in
The processor 602 of the door zone sensor unit 106 is at least configured to provide at least the following door zone information within the door zone of each floor: floor number, magnet type, identification code of the magnet, linear position of the elevator car, speed of the elevator car. The at least one Hall sensor 610 of the door zone sensor unit 106 is configured to obtain the strength of magnetic field as the elevator car 102 bypassing the at least one door zone magnet 114a-114n at the door zone. Based on the obtained magnetic field strength at least the linear position and the speed of the elevator car 102 within the door zone may be defined. For example, the speed of the elevator car 102 may be defined from a rate of change of the linear position of the elevator car 102 defined from the obtained strength of magnetic field as the elevator car 102 bypasses the at least one door zone magnet 114a-114n at the door zone. The number of Hall sensors 610 may be determined based on the number of the door zone magnets 114a-114n at the door zone of each floor 116a-116n. The RFID reader 612 of the door zone sensor unit 106 is configured to obtain at least the floor number, magnet type and identification code of the magnet from the RFID tag of the at least one door zone magnet 114a-114n. The door zone information may be obtained only within the door zone of each floor of the elevator shaft.
The processor 602 is arranged to access the memory 604 and retrieve and store any information therefrom and thereto. For sake of clarity, the processor 602 herein refers to any unit suitable for processing information and control the operation of the door zone sensor unit 106, among other tasks. The operations may also be implemented with a microcontroller solution with embedded software. Similarly, the memory 604 is not limited to a certain type of memory only, but any memory type suitable for storing the described pieces of information may be applied in the context of the present invention.
The absolute position information of the elevator car 102 may be defined substantially accurately by means of the method, safety control unit and elevator system as described above. Alternatively or in addition, the absolute position information of the elevator car 102 may be defined at two channels in order to certainly meet the SIL3 level accuracy requirements. In order to define two-channel absolute position information the pulse position information and door zone information may be obtained at two channels. The two-channel pulse position information may be obtained from of the pulse sensor unit 108 comprising one quadrature sensor and at least one processor at each channel. Furthermore, the two-channel door zone information may be obtained from the door zone sensor unit 106 comprising at least one Hall sensor and at least one processor at each channel. The above presented method safety control unit, and elevator system may be implemented for two channels similarly as described above for one channel.
Turning to
The first sensor is a pulse sensor unit 121 providing a pulse position information of the traction sheave of the hoisting machine 120 of the elevator car. The pulse sensor unit 121 comprises a magnetic sensor 122 measuring magnetic field variation from a rotating magnet ring 123 arranged in the traction sheave of the hoisting machine.
The first sensor 121 and the second sensor 108 are independent of each other, which means that failure of one sensor does not directly affect the other sensor. Thus, a reciprocal comparison of sensor readings of the separate sensors 121, 108 may provide information about operating condition of the sensor(s) 121, 108.
The elevator system 100 further comprises a drive unit 125, which is configured to supply electric power to the hoisting motor to drive elevator car 102. The elevator system 100 also has an elevator control unit 124, which is responsible of receiving car calls from elevator passengers and which also commands drive unit 124 such that elevator car can serve the generated car calls. Therefore elevator control unit 124 also monitors elevator car movement in elevator shaft. Accordingly, elevator control unit is connected to the pulse sensor units 108, 121.
Further, data received from the pulse sensor units 108, 121, it processed and memorized in the elevator control unit 124 for maintenance purposes. As pictured in
As mentioned above, elevator control unit 124 receives pulse position information during elevator travel continuously from the pulse sensor units 108, 121. A reference distance xref for an elevator car travel between different door zones is calculated and memorized during setup run. The setup run is performed before the elevator car 102 may be taken into actual operation. During the setup run the elevator car 102 may be configured to drive first either at the top floor or at the bottom floor and then the elevator car 102 is configured to drive the elevator shaft from one end to the other end. The setup run may comprise obtaining and storing pre-information about the at least one door zone magnet 114a-114n at the door zone of each floor of the elevator shaft. The pre-information may be stored in a non-volatile memory of the safety control unit. The pre-information may comprise at least the following: floor number, identification code, magnet type, pulse position information, linear position information. The linear position information of the elevator car within the door zone, the floor number, identification code, and magnet type may be obtained from the door zone sensor unit 106 comprising at least one Hall sensor and RFID reader as will be described later. The pulse position information may be obtained from the pulse sensor unit 108 as will be described later. The pulse position information and linear position information may be obtained at mid-point of each door zone magnet.
The reference distance xref is calculated from the pre-information as a distance between consecutive door zones in the shaft.
During an elevator car travel between a first and a second selected door zones, a first elevator car speed information v1 is determined continuously from the pulse position information of the first pulse sensor unit 121 and a second elevator car speed information v2 is determined continuously from the pulse position information of the second pulse sensor unit 108. This may be done by measuring number of pulses in a certain time interval or by measuring time difference between consecutive pulses, for example.
A cumulative sensor system error is calculated by integrating the difference between the first elevator car speed information v1 and the second elevator car speed information v2. This cumulative sensor system error is further divided with the reference distance xref to obtain a sensor system performance indicator Kp as a relative value, which is easier to process in the data analytics in the maintenance server 127. The sensor system performance indicator Kp calculation process may be represented with an equation as follows:
In first embodiment, the calculated sensor system performance indicators Kp are first memorized in the elevator control unit 124. In selected time intervals, e.g. once a day, the performance indicators Kp are transferred to the maintenance server 127. In the maintenance server, a sequence of consequent performance indicators is processed to identify e.g. growing trends which would give an indication of maintenance need of the pulse sensor system 108, 121. When maintenance need is determined, service request is established in the maintenance server 127, preferably already before the pulse sensor system is considered as defective. The service request scheduled and transmitted to a suitable maintenance unit (having required knowledge and a corresponding geographical location) such that maintenance can be done before the pulse sensor system fails.
In a second embodiment, statistics information is calculated in the elevator control unit 124 from the sensor system performance indicators Kp before they are sent to the maintenance server 127. In the maintenance server, the statistics information is then used instead of (or in addition to) the separate performance indicators to determine maintenance need. This may be advantageous such that non-relevant variation between separate sensor system performance indicators Kp may be omitted.
In some refinements, elevator control unit 124 also reads during elevator car travel continuously the supply frequency of the elevator hoisting motor of the hoisting machine 120 from the drive unit 125 and defines a third elevator car speed information therefrom. By comparing the first elevator car speed information v1 from the first pulse sensor unit 121 and the second elevator car speed information v2 from the second pulse sensor unit 108 with the third elevator car speed information, it is possible to define which sensor 108, 121 is defective and add this sensor identification information to the sensor system performance indicator Kp.
The present invention as hereby described provides great advantages over the prior art solutions. For example, the present invention improves at least partly the safety of the elevators. The present invention enables implementation of diagnosis and preventive maintenance of an absolute positioning by using already existing door zone sensor unit, elevator control unit and safety control unit together with additional substantially inexpensive components, such as magnet ring in OSG, and a pulse sensor unit comprising at least one quadrature sensor. The total costs of the additional components may be substantially less than the total costs of the prior art solutions. Moreover, in the present invention the travelling height is not limited, because the absolute position information may be defined continuously regardless of the place of the elevator car in the elevator shaft without any expensive magnetic tape or similar extending from end to end of the elevator shaft. Furthermore, the present invention enables two-channel absolute positioning for SIL3 safety integrity level that may be required for many safety functions in an elevator system.
The verb “meet” in context of an SIL3 level is used in this patent application to mean that a predefined condition is fulfilled. For example, the predefined condition may be that the SIL3 level accuracy limit is reached and/or exceeded.
This invention is also useful for many different kind of elevators, such as counterweightless elevators, multicar elevators, high-rise elevators, elevators propelled with linear motors, et cetera.
The specific examples provided in the description given above should not be construed as limiting the applicability and/or the interpretation of the appended claims. Lists and groups of examples provided in the description given above are not exhaustive unless otherwise explicitly stated.
| Number | Date | Country | Kind |
|---|---|---|---|
| 18156867.6 | Feb 2018 | EP | regional |
