The invention relates to solutions for monitoring the operation of a safety device of an elevator.
An elevator comprises safety devices, the purpose of which is to prevent dangerous situations related to use of the elevator. This type of safety device is e.g. an electromagnetic brake of an elevator, such as the machinery brake of the hoisting machine of the elevator or a guide rail brake of an elevator car.
Activation of the brake occurs by dropping out the brake by disconnecting the current supply to the magnetizing coil of the electromagnet of the brake. The current traveling in the magnetizing coil decreases with a time constant, the magnitude of which is usually at least some hundreds of milliseconds. The time constant is determined on the basis of, inter alia, the inductance of the magnetizing coil. After the current has decreased sufficiently, the force of the thruster spring in the electromagnetic brake exceeds the force of attraction with which the electromagnet pulls the surfaces of the brake that are on opposite sides of the air gap against each other, after which the brake shoe of a machinery brake or the prong of a guide rail brake starts to move towards the braking surface on a rotating part of the hoisting machine or towards the braking surface on a guide rail of the elevator car. The brake activates when the brake shoe/prong strikes against the braking surface to brake the movement of the hoisting machine/elevator car.
Fast and correctly-timed operation of a brake is important for, inter alia, preventing the drifting of an elevator car away from the stopping floor, because an elevator car drifting away from the stopping floor might cause a shearing hazard for a passenger remaining between the elevator hoistway entrance and the elevator car.
By means of fast and correctly-timed operation of the brake it can also be ensured that the elevator car is not able to collide with the end buffer of the elevator hoistway at an excessive speed. Implementing this is extremely challenging in elevators having a reduced end buffer e.g. owing to shallow top clearances or bottom clearances of the elevator hoistway with respect to the run speed of the elevator car. In this case the brake of the elevator must be activated to brake the speed of an elevator car approaching the end of the elevator hoistway sufficiently early and at precisely the correct moment in order for the speed of the elevator car to have time to decrease to the permitted buffer collision speed before a possible collision with a reduced end buffer. A polyurethane buffer, inter alia, is used as a reduced end buffer, which polyurethane buffer has a rather limited shock absorbing capability and which is also damaged by the force of even a rather small impact.
The operation of the brake can be accelerated by adding a special quenching circuit to the breaker circuit of the current supply, via which quenching circuit the current of the magnetizing coil of the electromagnet of the brake travels during disconnection of the current supply. A quenching circuit comprises one or more components, such as resistors or capacitors, which component(s) receive(s) the energy stored in the inductance of the magnetizing coil while simultaneously accelerating disconnection of the current of the magnetizing coil.
Activation of the brake might be slowed down e.g. owing to failure of the quenching circuit. The activation function of the brake might also be slowed down or even completely prevented as a consequence of, inter alia, a failure of an electronic or electromechanical component of the brake control circuit or of a short-circuit occurring in the brake control circuit, or, for instance, as a consequence of an earth fault of the brake control circuit.
The aim of the present invention is to solve the aforementioned problems as well as the problems relating to improving the safety of an elevator that are disclosed in the description of the invention below, by disclosing an improved solution for monitoring the operating capability of a drop-out safety device of an elevator. To achieve this aim the invention discloses a monitoring arrangement, according to claim 1, of an elevator and also a method, according to claim 15, for monitoring an elevator. The preferred embodiments of the invention are described in the dependent claims. Some inventive embodiments and also some inventive combinations of the various embodiments are also presented in the descriptive section and in the drawings of the present application.
The monitoring arrangement of an elevator according to the invention comprises a drop-out safety device of the elevator, an elevator component, which is in operational connection with the drop-out safety device of the elevator, a measuring device, with which the operation of the aforementioned elevator component is measured, and also a monitoring unit. The monitoring unit comprises an input for the measuring data of the aforementioned measuring device as well as a memory for setting one or more boundary conditions to be connected to the safe operation of the elevator component. The monitoring unit is configured to receive measuring data from the aforementioned measuring device and also to determine that the operating safety of the drop-out safety device of the elevator is endangered, if the measuring data received does not fulfill the boundary conditions set for the safe operation of the elevator component. When it determines that the operating safety of the drop-out safety device of the elevator is endangered, the monitoring unit is configured to form a monitoring signal for preventing a dangerous situation of the elevator. The measuring data does not fulfill the boundary conditions set for the safe operation of the elevator component e.g. when/if the measuring data received/some of the measuring data received is missing and/or the values, or at least some of the values, received by the measuring data deviate from the permitted values. In one preferred embodiment of the invention the aforementioned elevator component belongs to the drop-out apparatus with which a safety device of the elevator is dropped out.
In the invention operational connection of an elevator component to a drop-out safety device of the elevator means that a change in the operation of the elevator component causes a detectable change in the operation/response of the drop-out safety device and/or that a change in the operation of the drop-out safety device causes a detectable change in the operation/response of the elevator component. The invention enables improvement of the safety of an elevator by enhancing the efficiency of the monitoring of the operating capability of a safety device/safety devices of an elevator. The invention also enables the raising of the safety classification of present-day safety devices of an elevator, in which case an existing safety device/existing safety devices can be used in a new way or in a new context for ensuring the safety of an elevator. On the other hand, according to the invention it is also possible to take into use a completely new types of safety devices and/or safety arrangements of an elevator or to use those types of elevator components as safety devices of an elevator that have earlier only been used in connection with the normal functions of an elevator that are not safety-critical.
In the invention a drop-out safety device means the type of safety device that as a result of a drop-out procedure activates to ensure the safety of an elevator. A drop-out procedure is started if e.g. the safety circuit of the elevator has detected a dangerous situation or when some other event is detected that requires activation of a safety device for ensuring the safety of the elevator. In some cases also the control of the elevator can start a drop-out procedure; this type of control method can be necessary e.g. for testing the operating capability of a safety device of the elevator or otherwise when using a safety device of the elevator during normal operation of the elevator.
In a preferred embodiment of the invention the monitoring unit is configured to receive measuring data from the aforementioned measuring device in a drop-out situation of a safety device of the elevator. Consequently, by means of the invention the operating capability of a safety device/safety devices can be monitored in a drop-out situation of the safety device, which is often the most critical phase of all from the viewpoint of the operation of a safety device.
In one preferred embodiment of the invention the aforementioned elevator component is an electronic elevator component. In some embodiments the aforementioned elevator component is an electromechanical elevator component. In the invention, the term elevator component means an individual component, such as an electronic or electromechanical component; on the other hand, in the invention an elevator component can also mean a bounded functional entity formed from two or more components, such as from electronic and/or electromechanical components, such as e.g. a circuit card comprising electronic and/or electromechanical components, which circuit card can be treated as a single component in connection with, inter alia, servicing, installation and modernization of an elevator.
In one preferred embodiment of the invention one or more limit values commensurate with the measuring data of the aforementioned elevator component are recorded in the memory of the monitoring unit, which limit value(s) demarcate(s) a value plurality of permitted values for the measuring data, and the monitoring unit is configured to compare the received measuring data of the elevator component to the aforementioned value plurality of permitted values for measuring data and also to determine that the operating safety of a drop-out safety device of the elevator is endangered, if the value(s) of the received measuring data differ(s) from the value plurality of permitted values.
In one preferred embodiment of the invention the aforementioned safety device is an electromagnetic brake and the aforementioned elevator component is a brake control circuit.
In some embodiments the aforementioned safety device is an electrically activated overspeed governor and the elevator component is an activation circuit of an overspeed governor.
In one preferred embodiment of the invention the brake control circuit is configured for supplying current to the magnetizing coil of the electromagnetic brake of the elevator.
In one preferred embodiment of the invention the brake control circuit comprises a current quenching circuit for accelerating disconnection of the current of the magnetizing coil, and the monitoring unit is configured to determine the operating condition of the current quenching circuit.
In one preferred embodiment of the invention the aforementioned brake control circuit is configured for connection between a current source and the electromagnetic brake of an elevator. The monitoring arrangement comprises measuring means for measuring the fault current of the brake control circuit and also a limit value for the fault current of the brake control circuit. The monitoring unit is configured to compare the measuring data of the fault current being received from the aforementioned measuring means to the aforementioned limit value for fault current of the brake control circuit, and also to determine that the operating safety of a drop-out safety device of the elevator is endangered, if the magnitude of the measured fault current exceeds the magnitude of the aforementioned limit value for fault current.
In one preferred embodiment of the invention the monitoring arrangement is arranged to limit the operation of the elevator on the basis of a monitoring signal.
In one preferred embodiment of the invention the monitoring arrangement is arranged to prevent the next run of the elevator on the basis of a monitoring signal.
In one preferred embodiment of the invention the elevator comprises a safety circuit. In one preferred embodiment of the invention the safety circuit of the elevator comprises an input for receiving a monitoring signal. In a preferred embodiment of the invention the safety circuit of the elevator is configured to activate a machinery brake and also to disconnect the power supply to the elevator motor on the basis of a received monitoring signal.
In one preferred embodiment of the invention the drop-out of a safety device is arranged to be started on the basis of an activation signal for the safety device formed by the safety circuit of the elevator.
In one preferred embodiment of the invention the monitoring arrangement is configured to generate a defect notification on the basis of a monitoring signal.
In one preferred embodiment of the invention the monitoring arrangement is configured for sending a defect notification to a service center.
In the method according to the invention for monitoring an elevator, an elevator component is fitted into operational connection with a drop-out safety device of the elevator, one or more boundary conditions for safe operation are set for the elevator component, the operation of the elevator component is measured and also it is determined that the operating safety of the drop-out safety device of the elevator is endangered, if the measuring data does not fulfill the boundary conditions set for the safe operation of the elevator component.
In one preferred embodiment of the invention a safety device of the elevator is dropped out and the operation of an elevator component is measured in the drop-out situation of the safety device of the elevator.
In one preferred embodiment of the invention a monitoring signal is formed for preventing a dangerous situation of the elevator when determining that the operating safety of an elevator component is endangered.
The invention also relates to a method for monitoring the condition of the current quenching circuit of the magnetizing coil of an electromagnetic brake. In the method, one or more limit values are set to determine the permitted voltage range for the voltage over the current quenching circuit during a drop-out situation of the brake, the voltage over the current quenching circuit in a drop-out situation of the brake is measured, and it is deduced that the current quenching circuit has failed if the measured voltage deviates from the permitted voltage range.
The preceding summary, as well as the additional features and additional advantages of the invention presented below, will be better understood by the aid of the following description of some embodiments, said description not limiting the scope of application of the invention.
More detailed description of preferred embodiments of the invention
Instead of a permanent-magnet motor, also e.g. a squirrel-cage motor or reluctance motor can be used as an elevator motor 24. On the other hand, the elevator system can also comprise separate ropes/belts for the suspension and for the driving of the elevator car 25. In one alternative embodiment of the invention, the elevator car and also the counterweight are suspended in the elevator hoistway with one or more ropes or belts, which travel via a diverting pulley fixed, in a manner allowing rotation, to the top part of the elevator hoistway. In addition to this, the elevator comprises one or more separate traction belts, preferably a toothed belt, which is fixed in connection with the elevator car and the counterweight and which travels via a traction sheave of a hoisting machine disposed in the bottom end zone of the elevator hoistway. The traction belt is tensioned to be taut so that the elevator car is driven with the elevator motor by rotating the traction sheave of the hoisting machine.
According to the embodiment of
Activation of the brake 1 occurs by dropping out the brake 1 by disconnecting the current supply to the magnetizing coil 15 of the electromagnet of the brake. Disconnection of the current supply occurs by opening at least one of the two switches 32A, 32B in the brake control circuit 5. If the switch 32A is opened but the switch 32B is kept conductive, the current (I′,
For accelerating the activation of the brake 1, in the brake control circuit 5 a current quenching circuit 13, 14 according to
Failure of the current quenching circuit 13, 14, such as a short-circuit of the varistor 14, results in the energy of the magnetizing coil 15 of the brake no longer being converted into heat in the current quenching circuit 13, 14 in the same way as earlier, and disconnection of the current of the magnetizing coil 15 slows down. At the same time activation of the brake 1 in connection with accelerated disconnection of the current also slows down.
Since correctly timed and rapid activation of the brake 1 is of essential importance from the viewpoint of the safety of the elevator, the elevator system of
The operating condition of the current quenching circuit 13, 14 is monitored by measuring the voltage over the series circuit of the diode 13 and the varistor 14 with a test amplifier 7. A graph of the measured voltage 20 is illustrated in
Since failure of the current quenching circuit 13, 14 means that the brake 1 will no longer activate as quickly as earlier, the microcontroller determines on the basis of the failure observation of the current quenching circuit 13, 14 that the operating safety of the brake 1 is endangered and forms a monitoring signal 18 relating to this for sending to the elevator control unit 36 and also to a service center 19 of the elevator via communication channels between the brake control circuit 5 and the elevator control unit 36/service center 19. The elevator control unit 36 takes into account the failure of the current quenching circuit 13, 14 by limiting the movement of the elevator car 25 in the elevator hoistway by reducing the maximum speed and/or the maximum acceleration/deceleration of the elevator car 25 and also by otherwise preventing operating situations that would require accelerated activation of the brake 1. Consequently, the elevator control unit 36 prevents, among other things, driving with the elevator when a landing door and car door are open, i.e. the advance opening function of the doors. The return of the elevator to a normal state requires that a serviceman visit the elevator, replacing the failed circuit card of the brake control circuit 5 with a new one.
In a second embodiment of the invention the software of the elevator control unit 36 switches into drive prevention mode after receiving a monitoring signal 18, in which case a normal run of the elevator is completely prevented and only service drive is permitted until the brake control circuit 5/current quenching circuit 13, 14 is/are repaired.
The elevator system of
The overspeed governor 51 measures the speed of the elevator car 25 e.g. with an encoder fitted to the rope pulley 38 of the overspeed governor.
The overspeed governor 51 activates the safety gear 3 by locking the movement of the rope pulley 38 of the overspeed governor with a solenoid 39. The solenoid 39 is movably supported on a frame part 40, which is attached to a stationary part of the overspeed governor, so that movement of the rope pulley 38 is prevented by allowing the solenoid 39 to press onto the rope pulley 38. The solenoid 39 comprises pushing means, such as pusher springs, which press the solenoid 39 against the rope pulley 38. Detaching the solenoid 39, and keeping it detached from the rope pulley 38, requires that current is supplied to the coil 41 of the electromagnet of the solenoid 39, which current brings about an attractive force opposing the pushing force of the pushing means. The overspeed governor 51 is therefore configured to activate the gripping function always when the current supply to the coil 41 of the electromagnet of the solenoid is disconnected. The current supply to the coil 41 of the electromagnet of the solenoid occurs via the controllable switch 42 in the current supply circuit 4 of the coil 41 of the solenoid, so that the current supply to the coil 41 of the electromagnet of the solenoid is disconnected by opening the aforementioned controllable switch 42. The switch 42 is controlled open in response to a control formed by the safety circuit 23 of the elevator.
Failure of the current supply circuit 4 of the coil of the solenoid, such as failure of the switch 42 into a short-circuit, causes the current of the coil 41 of the solenoid to not disconnect and the gripping function does not in this case activate. For this reason the elevator system of
In one embodiment of the invention the monitoring arrangement of the safety gear of embodiment 2 is fitted into an elevator system according to the embodiment of
In the elevator system of
In the monitoring arrangement presented in
Owing to an earth fault situation of the control circuit 5, 6, the electromagnetic brake 1, 2 does not necessarily activate properly, on the other hand an earth fault situation of the current supply circuit 4 of the overspeed governor could also prevent operation of the overspeed governor/safety gear. Consequently, when it detects an earth fault situation of the control circuit 4, 5, 6, the control unit 8, 43 of the control circuit deduces that the operating safety of the electromagnetic brake/overspeed governor is endangered and forms a monitoring signal 18 for sending to the elevator control unit 36 and also to a service center 19 via communication channels between the control circuit 4, 5, 6 and the elevator control unit 36/service center 19. The software of the elevator control unit 36 switches into drive prevention mode after receiving a monitoring signal 18, such that use of the elevator is completely prevented until the earth fault situation in the control circuit 4, 5, 6 is rectified.
The invention is described above by the aid of a few examples of its embodiment. It is obvious to the person skilled in the art that the invention is not only limited to the embodiments described above, but that many other applications are possible within the scope of the inventive concept defined by the claims.
Number | Date | Country | Kind |
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20115983 | Oct 2011 | FI | national |
This application is a continuation of PCT International Application No. PCT/FI2012/050957 which has an International filing date of Oct. 5, 2012, and which claims priority to Finnish patent application number 20115983 filed Oct. 7, 2011, the entire contents of both which are incorporated herein by reference.
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Number | Date | Country | |
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Number | Date | Country | |
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Parent | PCT/FI2012/050957 | Oct 2012 | US |
Child | 14220375 | US |