Method of testing a mechanical brake in an elevator
By monitoring changes in motor drive torque and drop delay during elevator operation, the problem of the inability to dynamically test elevator mechanical brakes in existing technologies has been solved. This enables real-time diagnosis and dynamic monitoring of the brakes, improving the comprehensiveness and accuracy of the test.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- KONE OYJ
- Filing Date
- 2021-08-10
- Publication Date
- 2026-06-23
AI Technical Summary
Existing technologies cannot effectively monitor the dynamic torque and drop delay of elevator mechanical brakes during testing, and the test requires the car to be stationary, making it impossible to conduct a comprehensive inspection under dynamic conditions.
By generating brake drop commands during elevator operation, monitoring the change pattern of motor drive torque, recording motor current and drop delay, and using speed controller and main controller for real-time diagnosis, the system ensures that the brake works normally under dynamic conditions.
It enables real-time monitoring of the dynamic torque and drop delay of the elevator mechanical brake, ensuring that the brake works normally under dynamic conditions, improving the comprehensiveness and accuracy of the test, and reducing additional wear on the brake.
Smart Images
Figure CN114074870B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for testing mechanical brakes in elevators. Background Technology
[0002] An elevator may include a car, shaft, hoisting mechanism, hoisting ropes, and counterweight. A separate or integrated car frame may surround the car.
[0003] The hoisting mechanism can be positioned within a shaft. It may include an electric drive, a traction pulley, and a mechanical brake. The electric drive may include an electric motor and a drive unit that controls the motor. The car frame may be connected to the counterweight via the traction pulley and hoisting ropes. The electric motor causes the traction pulley to rotate, moving the car up and down within the shaft. The mechanical brake stops the rotation of the traction pulley, thereby stopping the elevator car's movement.
[0004] The car frame can be supported by a guiding device on guide rails extending vertically within the shaft. The guide rails can be attached to the side wall structure within the shaft using fastening brackets. As the car moves up and down within the shaft, the guiding device holds the car in the appropriate position in the horizontal plane. Counterweights can be supported accordingly on the guide rails attached to the wall structure of the shaft.
[0005] The elevator car can transport people and / or goods between platforms of a building. The shaft can be configured such that the wall structure is formed of solid walls, or that the wall structure is formed of open steel structures.
[0006] A mechanical brake may consist of at least one electromechanical brake. The mechanical brake constitutes a safety device for the elevator. It applies braking force to the traction pulley or the rotating shaft of the hoisting mechanism to stop the movement of the hoisting mechanism, thereby also stopping the movement of the elevator car. A mechanical brake may include at least two brakes, such as two, three, or four. The dimensions of the mechanical brake shall conform to EN 81-20:2014, enabling it to stop the elevator machinery when the car is traveling downwards at rated speed and rated load plus a 25% overload (i.e., 125% load). If one brake fails, the other brake shall still be able to decelerate, stop, and hold the elevator car stationary at rated load (i.e., 100% load). As a safety device in the elevator, the mechanical brake should therefore be tested periodically to ensure its proper functioning.
[0007] An electromagnetic brake may include a frame portion and an armature portion movably attached to the frame portion. A spring device may be arranged to operate between the frame portion and the armature portion to push the armature portion away from the frame portion when the mechanical brake is actuated. A brake shoe acting on a rotating braking surface may be attached to the armature portion. The rotating braking surface may be connected to a traction pulley. When the mechanical brake is actuated, the brake shoe is pushed against the rotating braking surface. An electromagnetic device may be further arranged in the frame portion. The magnetic field of the electromagnetic device overcomes the force of the spring device to pull the armature portion toward the frame portion. When the electromagnet is activated, the mechanical brake is deactivated, i.e., the brake shoe is pulled away from the braking surface. Conversely, when the electromagnet is deactivated, the mechanical brake is activated, i.e., the brake shoe is pushed toward the braking surface. The mechanical brake may be a shoe brake, a drum brake, a disc brake, or any corresponding mechanical brake.
[0008] Existing braking tests are based on the principle that one of the mechanical brakes is engaged when the car stops at the platform. Therefore, the remaining brakes in the mechanical brake system will be subjected to forces originating from gravity (the imbalance between the car and the counterweight) or from a combination of gravity and additional forces generated by the motors in the hoisting mechanism. Monitoring is based on detecting the movement of the hoisting mechanism under these conditions. Each brake in the mechanical brake system can be tested simultaneously. Summary of the Invention
[0009] The purpose of this invention is to provide an improved method for testing mechanical brakes in elevators.
[0010] The method for testing mechanical brakes in elevators according to the present invention is defined in claim 1.
[0011] An elevator includes a car that is movable in a shaft, an electric motor for moving the car, a drive unit for controlling the electric motor, and a mechanical brake for braking and holding the car.
[0012] Methods for testing mechanical brakes include
[0013] By adjusting the drive torque of the electric motor using a drive unit, the car is moved using the electric motor according to the drive curve.
[0014] A command is generated to deactivate the mechanical brakes while the car is moving.
[0015] Monitor the drive torque of the electric motor, and
[0016] During the predetermined time period from the generation of the mechanical brake to the brake deactivation command, if the drive torque of the motor does not follow the expected drive torque variation pattern, it indicates that the mechanical brake is not working properly; otherwise, it indicates that the mechanical brake is working properly.
[0017] The drive unit can calculate the drive curve of the car moving between platforms in a building. The drive unit may include a speed controller. The speed controller can adjust the drive torque of the electric motor to achieve the drive curve of the car.
[0018] The mechanical brakes may include at least two brakes, such as two, three, or four brakes. The mechanical brakes should be sized to stop the elevator machinery when the car is traveling downwards at rated speed and rated load plus a 25% overload (i.e., 125% load). If one brake fails, the other brake should still be able to decelerate and stop the elevator car at rated load (i.e., 100% load) and keep the elevator car stationary. Methods for testing the functionality of the mechanical brakes can be stored in the memory of the elevator controller.
[0019] Therefore, a brake-down command is sent to the mechanical brake while the elevator car is running. The drive torque of the motor can be monitored. If the mechanical brake is functioning correctly, it will abut against the traction pulley of the hoisting mechanism after a specific braking delay and begin braking the movement of the hoisting mechanism. Simultaneously, the speed controller of the drive unit attempts to maintain the current speed conditions by increasing the drive torque. The drive torque or drive torque reference can be monitored. If the drive torque or drive torque reference forms an increasing pattern consistent with the expected braking torque of the mechanical brake, it can be concluded that the mechanical brake is functioning correctly. Otherwise, if the drive torque does not increase as expected within a predetermined time period, it can be concluded that the mechanical brake is not functioning correctly. In the latter case, the elevator may be taken out of service and / or a maintenance request may be generated for a remote service center.
[0020] Braking tests can be performed while the elevator car is traveling in the light direction. The light direction refers to the car traveling upwards in the shaft with the car empty and downwards with the car fully loaded. The car speed during the braking test can be the car's nominal speed or some other lower test speed.
[0021] The weight of the elevator ropes may not be compensated, causing the degree of elevator imbalance to vary in different parts of the shaft. Therefore, the car's position and the motor torque just before the mechanical brake engages during braking testing can be recorded. This makes it possible to determine the elevator's imbalance during testing. The test can be conducted at locations in the shaft where the elevator imbalance is at its minimum and at locations where the imbalance is at its maximum during elevator startup.
[0022] During a single test drive, one or more brakes of the mechanical brake system can be tested. When a brake under test passes the test, the control system pulls up the brake (deactivates the brake) and lowers it (activates) the next brake. There is no need to stop the elevator between tests. In some other embodiments, a subset of brakes can be tested simultaneously, i.e., more than one but less than all brakes in a set of brakes.
[0023] If the mechanical brake consists of two brakes, the two brakes can be tested alternately during a single elevator run, so that a brake-down command is issued to the brake under test while the other brake in the mechanical brake remains open.
[0024] Measurement results and acceptable limits can be transmitted to a cloud server. Therefore, trends can be observed from the data in the cloud server using algorithms, and the correct timing for maintenance actions can be determined.
[0025] In modern vector control electric drives, the motor current, or motor current reference, is proportional to the motor's drive torque, especially in the case of permanent magnet motors. Therefore, the motor current, or motor current reference, is a parameter that can actually be monitored.
[0026] During the same test, the activation delay (deactivation delay) of the mechanical brake can also be measured. This is done by measuring the time delay from the moment the brake deactivation command is issued to the moment the change pattern of drive torque is detected. The time delay of engaging the mechanical brake should not be too long. Therefore, if the measured time delay exceeds a given threshold, an indication of abnormal mechanical brake operation should be issued.
[0027] Once the braking test is successfully completed, the elevator can continue to run uninterrupted to the destination platform.
[0028] Alternatively, upon detecting a desired change in drive torque, the drive torque can be interrupted, causing the mechanical brakes to bring the car to a stop. The car's stopping distance can be recorded. Additional diagnostic data for the mechanical brakes can be obtained by verifying that the car's stopping distance is within the desired limits.
[0029] The brake drop command signifies the activation of the mechanical brake. The mechanical brake can be activated by disabling the electromagnet within it, i.e., by cutting off the current supply to the electromagnet. The spring mechanism in the mechanical brake then presses one or more brake shoes against the rotating braking surface, thereby braking the movement of the lifting machinery. In place of the shoe brake, a drum brake, disc brake, or any corresponding mechanical brake can be used.
[0030] Existing brake testing techniques do not measure the drop delay of mechanical brakes. Novel brake testing methods make it possible to measure the drop delay or activation delay of mechanical brakes. It is important to monitor the drop delay of mechanical brakes to ensure they function properly under all conditions.
[0031] Existing braking tests measure braking force under static conditions, where the lifting mechanism is stationary during the test. However, the torque generated by the brake under dynamic conditions may differ from that generated under static conditions. This novel braking test makes it possible to measure the dynamic torque of a mechanical brake.
[0032] Contaminants can accumulate on the friction surfaces of brake shoes in mechanical brakes. At the onset of a braking event, these contaminants can affect brake characteristics. During novel braking tests, contaminants will have time to wear away from the friction surfaces of the brake shoes.
[0033] The novel braking test can also eliminate additional wear on the brakes because it can be performed at lower test speeds. Attached Figure Description
[0034] The invention will now be described in more detail with reference to the accompanying drawings and preferred embodiments, wherein...
[0035] Figure 1 A side view of the elevator is shown.
[0036] Figure 2 A side view of the elevator's mechanical braking system is shown.
[0037] Figure 3 A flowchart is shown for testing the mechanical brake of an elevator. Detailed Implementation
[0038] Figure 1 A side view of the elevator is shown.
[0039] An elevator may include a car 10, an elevator shaft 20, a hoisting mechanism 30, hoisting ropes 42, and a counterweight 41. A separate or integrated car frame 11 may surround the car 10.
[0040] The hoisting mechanism 30 can be located within the shaft 20. The hoisting mechanism may include electric actuators 31 and 32, a traction pulley 33, and a mechanical brake 100. The electric actuators 31 and 32 may include a motor 32 and a drive unit 31 that controls the motor 32. The motor 32 may be a permanent magnet motor, and the drive unit 31 may be a frequency converter. The drive unit 31 controls the motor 32, and the motor 32 causes the traction pulley 33 to rotate. The car frame 11 can be connected to the counterweight 41 via the traction pulley 33 and a hoisting rope 42. The rotation of the traction pulley 33 caused by the motor 32 will cause the car 10 to move upward and downward in the vertically extending elevator shaft 20 in the vertical direction Z. The mechanical brake 100 can stop the rotation of the traction pulley 33, thereby stopping the movement of the elevator car 10.
[0041] The car frame 11 can be supported by a guide device 27 on a guide rail 25 extending vertically in the shaft 20. The guide device 27 may include rollers that roll on the guide rail 25 or sliding shoes that slide on the guide rail 25 as the car 10 moves up and down in the elevator shaft 20. The guide rail 25 can be attached to the side wall structure 21 in the elevator shaft 20 by means of a fastening bracket 26. As the car 10 moves up and down in the elevator shaft 20, the guide device 27 holds the car 10 in place in the horizontal plane. The counterweight 41 can be supported in a corresponding manner on the guide rail attached to the wall structure 21 of the shaft 20.
[0042] The elevator car 10 can transport people and / or goods between platforms of a building. The elevator shaft 20 can be configured such that the wall structure 21 is formed of a solid wall, or such that the wall structure 21 is formed of an open steel structure.
[0043] The elevator can be controlled by the main controller 300.
[0044] Figure 2 A side view of the elevator's mechanical braking system is shown.
[0045] The car 10 can be suspended on the first side of the traction pulley 33, while the counterweight 41 can be suspended on the opposite second side of the traction pulley 33. The lifting rope 42 can travel from the car 10 through the traction pulley 33 to the counterweight 41. The traction pulley 33 can be driven by an electric motor 32. The electric motor 32 can be a synchronous permanent magnet motor. The electric motor 32 can be controlled by a drive unit 31. The drive unit 31 can be a frequency converter.
[0046] The mechanical brake 100 may include two electromagnetic brakes 110 and 120 acting on the traction pulley 33. The electromagnetic brakes 110 and 120 may be controlled by the mechanical brake controller 200.
[0047] The elevator, drive unit 31, and brake controller 200 can be controlled by the main controller 300. The traction pulley 33 may be equipped with a motion measuring device 130. The motion measuring device 130 may be formed by a tachometer.
[0048] Figure 3 A flowchart is shown for testing the mechanical brake of an elevator.
[0049] Step 501 involves moving the car using the motor according to the drive curve by adjusting the drive torque of the motor. The motor can be controlled by a drive unit. The drive unit can be controlled by the elevator's main controller.
[0050] Step 502 includes generating a brake drop command for the mechanical brake. The brake drop command may be generated by the mechanical brake controller and / or the main controller.
[0051] Step 503 involves monitoring the drive torque of the electric motor. This can actually be done by monitoring the motor current. In modern vector control electric drives, the motor current is proportional to the motor's drive torque, especially in the case of permanent magnet motors.
[0052] Step 504 includes determining whether the drive torque of the electric motor follows a desired variation pattern during a predefined time period from the generation of the mechanical brake to the start of the brake drop command.
[0053] Step 505 includes instructing the mechanical brake to operate normally if the answer to step 504 is yes.
[0054] Step 506 includes indicating that the mechanical brake is not functioning properly if the answer to step 504 is no.
[0055] The application of this invention is not limited to the elevator disclosed in the accompanying drawings. This invention can be used with any type of elevator, such as elevators with or without a machine room, and elevators with or without a counterweight. The counterweight can be positioned on any side wall, either side wall, or the rear wall of the elevator shaft. The drive unit, motor, traction pulley, and mechanical brake can be positioned in the machine room or at a location within the elevator shaft. The car guide rails can be positioned on opposite side walls or the rear wall of the shaft in a so-called ruck-sack elevator.
[0056] It will be apparent to those skilled in the art that the concept of this invention can be implemented in various ways as technology advances. The invention and its embodiments are not limited to the examples described above, but can be varied within the scope of the claims.
Claims
1. A method for testing a mechanical brake in an elevator, the elevator comprising a car (10) movably arranged in a shaft (20), an electric motor (32) for moving the car (10), a drive unit (31) for controlling the electric motor (32), and a mechanical brake (100) for braking and holding the car (10), the method comprising By adjusting the driving torque of the motor (32) using the drive unit (31), the car (10) is moved using the motor (32) according to the drive curve. A brake-down command is generated to the mechanical brake (100) while the car (10) is moving. Monitor the drive torque of the electric motor (32), and During the predetermined time period from the generation of the brake drop command of the mechanical brake (100), if the drive torque of the motor (32) does not follow the expected drive torque change pattern, it indicates that the mechanical brake is not working properly; otherwise, it indicates that the mechanical brake (100) is working properly.
2. The method of claim 1, wherein, The elevator car (10) moves in the light direction of the elevator car (10) according to the drive curve using an electric motor (32).
3. The method of claim 1 or 2, wherein, The mechanical brake (100) includes at least two brakes (110, 120), which are tested in turn such that a brake drop command is issued to the brake under test (110, 120), while the other brakes remain open.
4. The method according to any one of claims 1 to 3, wherein, The brake drop delay is measured, which starts from the moment the brake drop command is issued and continues until the moment the drive torque change pattern is detected, and if the brake drop delay exceeds a predetermined threshold, it indicates an operational abnormality of the mechanical brake (100).
5. The method according to claim 4, wherein, When the desired driving torque change pattern is detected, the driving torque is interrupted, the resulting stopping distance of the car (10) is measured, and the stopping distance of the car (10) is verified to be within the desired limit.
6. The method according to any one of claims 1 to 5, wherein, The desired drive torque variation pattern is based on the desired increase in drive torque and / or the desired rate of increase.
7. An elevator comprising a car (10) movably arranged in a shaft (20), an electric motor (32) for moving the car (10), a drive unit (31) for controlling the electric motor (32), a mechanical brake (100) for braking and holding the car (10), a mechanical brake controller (200) for controlling the mechanical brake (100), and a main controller (300), wherein, The main controller (300) controls the elevator according to any one of claims 1-6.
8. A computer program product comprising program instructions that, when run on a computer, cause the computer to perform the method as described in any one of claims 1-6.