The invention relates to preventing the unintended movement of an elevator car and more particularly to preventing the drifting of an elevator car away from the stopping floor.
An elevator hoisting machine comprises one or more machinery brakes, which when activated lock the hoisting machine in position when the elevator stops at a stopping floor. When the elevator is stopped the doors of the elevator car as well as the doors on the stopping floor are opened, in which case passengers are able to leave the elevator car and also to move into the elevator car. In addition, so-called advance opening functions are known in the art, wherein the doors start to be opened immediately when the elevator car arrives in the door zone of the stopping floor, while the elevator car is still moving.
Malfunction of the machinery brakes might cause a dangerous situation for the users of the elevator. A particularly dangerous situation arises if the elevator car drifts from the stopping floor, e.g. due to failure of a machinery brake, exactly when a passenger moving into the elevator car or exiting the elevator car is in the area between the stopping floor and the elevator car.
Publication WO 2007020325 A2 presents a solution to the problem, wherein the operation of the machinery brakes is monitored by activating the brakes sequentially such that initially only the first brake is activated, and the other brakes are activated with a delay. The operating condition of the first brake is monitored by measuring the movement status of the elevator when only the first brake is activated. The solution therefore enables regular and automatic monitoring of the operating condition of the brakes.
Although the aforementioned solution does improve the monitoring of the operating condition of the brakes, and thereby reduces the risk of the drifting of an elevator car away from the stopping floor, other issues relating to the operation of an elevator at the stopping floor must also be addressed. One such issue that must be addressed is a control error of the machinery brake and/or of the elevator motor. This type of control error could be a consequence e.g. of a drive malfunction or of an operating malfunction. Experts subordinate to, and under the direction of, the applicant are thus continuously striving to analyze elevator operation and to make elevators even safer in operation.
The object of the invention is to provide a solution to the problem of the drifting of an elevator car away from the stopping floor and for preventing the dangerous situation caused by this. To achieve this aim the invention discloses a method and an arrangement for suppressing the drifting of an elevator car away from the stopping floor. The preferred embodiments of the invention are described herein.
In relation to the characteristic attributes of the invention, reference is made to the claims.
In the solution according to the invention the drifting of an elevator car away from the stopping floor is prevented a) by monitoring the operating condition of one or more machinery brakes of the hoisting machine of the elevator regularly; b) by stopping the elevator car leaving the door zone of the stopping floor when the door of the elevator car and/or the landing door is/are open by using the aforementioned one or more machinery brakes of the hoisting machine; c) by preventing the starting of the next run of an elevator car that has left the door zone of the stopping floor when the door of the elevator car and/or the landing door is/are open; and d) by recording information about the drive prevention in the non-volatile memory of the elevator control unit. By regularly monitoring the operating condition of one or more machinery brakes of the hoisting machine of an elevator it is endeavored to ensure that the aforementioned one or more machinery brakes of the hoisting machine of the elevator are in good operating condition in order to prevent the drifting of an elevator car away from the stopping floor in a situation, in which the elevator car is detected leaving the door zone of the stopping floor when the door of the elevator car and/or the landing is/are open. Furthermore, by preventing the starting of the next run of an elevator car that has left the door zone of the stopping floor it can be ensured that the elevator car is no longer able to continue its travel away from the stopping floor. This is important because movement of the elevator car might, if it continued, cause a shearing hazard to an elevator passenger who has remained between the stopping floor and the elevator car. When information about the drive prevention is also recorded in the non-volatile memory of the elevator control unit, a dangerous situation that would be caused by loss of the drive prevention data when the memory resets, e.g. owing to an electricity outage, can be prevented. This prevention of the resetting of the memory is possible because non-volatile memory retains its data also over an electricity outage. These types of non-volatile memories are e.g. flash EEPROM memory and also e.g. RAM memories with battery backup.
In a preferred embodiment of the invention braking force is exerted on the hoisting machine with at least one, preferably two or more, machinery brakes, which braking force is dimensioned to stop an essentially empty or fully loaded elevator car leaving the door zone of the stopping floor within a stopping distance, which stopping distance is essentially shorter than the length of the entrance of the elevator car in the direction of movement of the elevator car. When the operating condition of the aforementioned one or more machinery brakes is also monitored regularly, it can be ensured that after the movement of an elevator car that has left the door zone of the stopping floor when the door of the elevator car and/or the landing door is/are open has been stopped, there is still sufficient space between the stopping floor and the door opening of the elevator car for an elevator passenger that has possibly remained between the stopping floor and the door opening of the elevator car.
The solution according to the invention can be implemented fully, or at least in large part, with the existing components in elevators. Therefore the solution can be taken into use easily in both new and also old elevators, for instance in connection with a modernization of an elevator.
By means of the invention the possibility of an elevator car drifting away from the stopping floor and/or the danger caused to the passengers of an elevator by the drifting from the stopping floor can be further reduced.
The aforementioned 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.
In the following, the invention will be described in more detail by the aid of some examples of its embodiments, which in themselves do not limit the scope of application of the invention, with reference to the attached drawings, wherein
Two electromagnetic machinery brakes 3, e.g. a drum brake or a disc brake, are fixed to the frame of the hoisting machine 2 of the elevator, which brakes when activated are connected to the drum brake or disc brake of a rotating part of the hoisting machine, depending on the operating method of the brake. When they engage, the machinery brakes 3 start to brake the movement of the elevator car 1.
The power supply to the hoisting machine occurs from the electricity network 33 with the drive unit 32 of the hoisting machine. The electricity supply to the electromagnets of the machinery brakes 3 occurs with a brake control unit 29. The machinery brakes 3 open when sufficient current is supplied to the electromagnets and activate when the flow of current in the electromagnets ceases.
The door zone 4 of the stopping floor 10 means the location of the elevator car 1 in the elevator hoistway 34, in which location the floor of the elevator car 1 is on essentially the same level with the floor of the stopping floor 10. The door zone can be set using e.g. the arrangement illustrated in
A control command for opening or for closing the brake is given to the brake control unit 29 with the drive unit 32 of the hoisting machine. The arrangement for preventing the drifting of an elevator car 1 away from the stopping floor comprises a monitoring part 16 of the operating condition of the machinery brake of the elevator, which part is fitted as a part of the software of the drive unit 32 of the hoisting machine.
In one embodiment of the invention a moment in the direction of the rotational movement of the hoisting machine is exerted on the hoisting machine 2 of the elevator, which moment essentially corresponds to the maximum permitted imbalance of the elevator. The elevator car 1 is in this case held in its position in the door zone 4 of the stopping floor when only the first of the machinery brakes 3 is activated and when the second of the machinery brakes is open. Movement of the hoisting machine 2 of the elevator car is determined with an encoder fitted co-axially with the axis of rotation to a rotating part of the hoisting machine, and possible slipping of the machinery brake is detected by examining the movement signal 12 received from the encoder. If it is detected that the machinery brake is slipping, it is deduced that the operating condition of the activated machinery brake in question has deteriorated and both machinery brakes 3 are immediately activated.
In a second embodiment of the invention the machinery brakes 3 of the hoisting machine are controlled and the operation of the machinery brakes 3 is measured with a microswitch 13 that is fitted between parts of the machinery brake that move with respect to each other, which microswitch changes its state when the machinery brake 3 activates/opens. If the state of the microswitch 13 does not change in a predetermined manner as a result of a control command of the machinery brake 3, it is deduced that the operability of the machinery brake 3 in question has deteriorated.
Regular monitoring of the operating condition of the machinery brakes 3 is necessary because the friction coefficient between the brake shoe and the brake drum or brake disc of the machinery brake can be reduced owing to, e.g. wear of the brake or some other reason. A contaminating substance such as oil or dirt can find its way onto the braking surface, or the brakes can be incorrectly adjusted.
When the operating condition of a machinery brake 3 is detected to have deteriorated, information about this is recorded in the non-volatile memory 9 of the elevator control unit 8, and the next run of the elevator is prevented.
The arrangement for preventing the drifting of an elevator car away from the stopping floor also comprises a monitoring part 17 of the movement of the elevator car. As presented in
The status information of the contactor 19 of the monitoring part 17 is transferred to the elevator control unit 8 with a conductor 22 between the supervision circuit 21 and the elevator control unit 8. On the basis of the status information of the contactor 19, the elevator control unit 8 detects whether the elevator car 1 has left the door zone 4 when the door 6 of the elevator car and/or the landing door 37 is/are open. If the elevator control unit 8 has detected that the elevator car 1 has left the door zone 4 when the door 6 of the elevator car and/or the landing door 37 is/are open, the elevator control unit 8 switches the elevator into a control mode, in which the starting of the next run of the elevator is prevented. Information about the drive prevention of the elevator is also recorded in the non-volatile memory 9 of elevator control unit 8. Non-volatile memory means the type of memory, in which the recorded data is retained also over an electricity outage. These types of memories are e.g. flash EEPROM memory and also RAM memory, the electricity supply of which is backed up with a separate accumulator or battery.
Drive prevention data can also, if necessary, be sent e.g. to the service center via a wireless link.
The elevator control unit 8 comprises a display 25, with which a defect notification is displayed about the elevator car 1 leaving the door zone 4 when the door 6 of the elevator car and/or the landing door 37 is/are open.
Deactivation of the drive prevention of an elevator requires that a serviceman visits the elevator when deactivating the drive prevention using the keyboard 11 of the elevator control unit 8. At the same time the serviceman can perform an inspection procedure and/or servicing procedure of at least one machinery brake 3 after reading the defect notification.
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 limited only to the embodiments described above, but that many other applications are possible within the scope of the inventive concept defined by the claims presented below.
Number | Date | Country | Kind |
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20090335 | Sep 2009 | FI | national |
This application is a continuation of PCT/FI2010/000055 filed on Sep. 8, 2010, which is an international application and claims priority from FI 20090335 filed on Sep. 16, 2009, the entire contents of each of which are hereby incorporated by reference.
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Number | Date | Country | |
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Parent | PCT/FI2010/000055 | Sep 2010 | US |
Child | 13421494 | US |