Method for testing safety properties of an elevator

Abstract

A method for testing safety properties of an elevator comprises performing a balance check of the elevator upon request.

Description

Technical Field

[0001] This invention relates to a method for testing the safety characteristics of elevators. Background Technology

[0002] An elevator may include a car, shaft, hoisting mechanism, 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 a drive unit, an electric motor, a traction sheave, and a mechanical brake. The hoisting mechanism allows the elevator car to move up and down within the shaft. The mechanical brake stops the rotation of the traction sheave, thereby stopping the elevator car's movement.

[0004] The car frame can be connected to the counterweight via ropes through a traction sheave. The car frame can also be supported by a sliding device on guide rails extending vertically within the shaft. The guide rails can be attached to the side wall structure of the shaft using fastening brackets. As the car moves up and down within the shaft, the sliding device holds the car in a horizontal position. The counterweight can be supported on the guide rails, which are attached to the shaft wall structure, in a corresponding manner.

[0005] The elevator car can transport people and / or goods between floors 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 two electromechanical brakes. The brake serves as a safety device to apply braking force to the traction sheave or the rotating shaft of the traction mechanism to prevent movement of the traction mechanism, thereby also preventing movement of the elevator car. The mechanical brake should be sized to conform to EN81-20:2014 so as to bring the elevator machinery to a stop when the car is traveling downwards at rated speed and with a 25% overload (i.e., 125% load) of rated load. If one brake fails, the other brake should still be able to decelerate, stop, and keep the elevator car stationary at rated load (i.e., 100% load).

[0007] Due to its nature as a safety device, the operating condition of the mechanical brake must be checked.

[0008] EP1701904B1 discloses a method for testing the condition of elevator brakes. According to this method, one brake is raised while the other brake, the engaged brake, is subjected to a test load for testing braking torque. If movement of the traction sheave is detected during the test, the brake is considered faulty.

[0009] EP1915311B1 discloses a method for ensuring operational safety in an elevator system. According to this method, only one brake is engaged at the end of elevator operation, while the other brake is engaged with a delay. When the first brake is engaged, the torque of the drive motor is removed. If movement of the traction sheave is detected on it, the brake is considered faulty. Summary of the Invention

[0010] Existing technological methods for monitoring elevator brakes may have problems.

[0011] This issue relates to improper balance in the elevator. Improper balance can lead to an incorrect (insufficient) test load being applied to the brake during braking tests. Therefore, when insufficient load is applied to the brake during testing, the braking test will effectively become invalid.

[0012] This situation can be illustrated with an example. In an elevator with a rated load of 1000 kg and a balance ratio of 50%, the counterweight should correspond to the weight of the empty elevator car plus 500 kg. If the elevator's balance ratio is incorrectly set to 30% instead of the expected 50%, a test load of 300 kg will be applied to the lifting mechanism during brake testing, instead of the expected 500 kg. Therefore, when the brake can withstand a test load of 300 kg, it will pass the braking test, which is only 60% of the expected test load of 500 kg.

[0013] An incorrect balance ratio can cause the elevator car to operate using brakes that fail to properly stop its movement. Incorrect brake test results can also cause this problem. Due to the imbalance, the mass to be decelerated may be greater than the expected mass. This is especially true for a fully loaded elevator car moving downwards.

[0014] The elevator's balance may be unexpectedly altered in connection with maintenance or renovation work. For example, the interior decor of the car may be changed. Furthermore, during special elevator operations, such as operations during temporary construction periods, (temporary) balance changes may occur.

[0015] This invention relates to an improved method for testing the safety characteristics of elevators.

[0016] Claim 1 defines a method for testing the safety characteristics of an elevator according to the present invention.

[0017] This invention will increase elevator safety. The brake will be tested using a test load that corresponds to the actual test load calculated based on a balance check, rather than a calculated test load based on the elevator's assumed balance.

[0018] Methods for testing the safety characteristics of an elevator include performing a balance check on the elevator according to a predetermined schedule. The imbalance calculated based on the balance check results is compared with the elevator's balance and rated load values ​​specified in its basic characteristics. The elevator's basic characteristics can be stored in an electronic log.

[0019] The balance check should be performed using an empty car. Before performing the test, the load weight information should provide near-zero load information. Failure to detect a near-zero load in the car within a predetermined time period may be due to additional trim added to the car. This new load value can be defined as the new calibration zero load.

[0020] Modifying the zero-load setting, if the counterweight remains unchanged, will typically cause a change in balance. The new zero-load setting, the actual balance after setting the new zero-load, and the elevator's relevant original basic characteristics (such as rated load and balance) can be reported to the cloud. Information from the elevator controller can be transmitted to the cloud via wired or wireless communication.

[0021] The schedule for balance checks can be based on a timeline. Additionally or alternatively, the schedule must include a time window from the date the request is received for the balance checks to be performed. This request can be generated by a remote entity such as a remote server or cloud service.

[0022] If the balance check is not performed according to the predetermined schedule, normal elevator operation may be prevented.

[0023] The results of the balance check can be compared with predetermined standards.

[0024] Predetermined criteria can be based on log values ​​collected during earlier testing.

[0025] If the results of the balance check meet the predetermined criteria, then the braking test can be permitted.

[0026] If the balance check results do not meet the predetermined standards, the elevator may be prevented from operating normally.

[0027] When determining whether the balance meets predetermined criteria, at least one balance error tolerance may be used. The balance error tolerance may be defined as a% of the rated load, a defined constant value, or a combination of both. A first balance error tolerance may be defined such that if this first balance error tolerance is exceeded, the elevator is stopped from service. A second balance error tolerance may be defined such that if this second balance error tolerance is exceeded, a warning code is issued.

[0028] Furthermore, degraded elevator operation is permitted if the second balance tolerance is exceeded. During degraded elevator operation, the maximum permissible load on the car can be reduced. The reduction in the maximum load on the car can be determined based on the results of a balance check. The car load can be measured during degraded operation, for example, using a load cell. If the measured load on the car exceeds the reduced maximum load, elevator operation can be refused.

[0029] After the balance check is performed, the mechanical brakes of the elevator can be tested.

[0030] Braking tests of mechanical brakes can be motor-assisted braking tests. Attached Figure Description

[0031] The present invention will now be described in more detail with reference to the accompanying drawings and preferred embodiments, wherein...

[0032] Figure 1 A side view of the elevator is shown.

[0033] Figure 2 A side view of the elevator's mechanical braking system is shown.

[0034] Figure 3 A flowchart for testing the safety features of an elevator is shown. Detailed Implementation

[0035] Figure 1 A side view of the elevator is shown.

[0036] An elevator may include a car 10, an elevator shaft 20, a hoisting mechanism 30, ropes 42, and a counterweight 41. A separate or integrated car frame 11 may surround the car 10.

[0037] The hoisting mechanism 30 can be positioned within the shaft 20. The hoisting mechanism may include a drive 31, a motor 32, a traction sheave 33, and a mechanical brake 100. The hoisting mechanism 30 can move the elevator car 10 upwards and downwards in the vertical direction Z within the vertically extending elevator shaft 20. The mechanical brake 100 can stop the rotation of the traction sheave 33, thereby stopping the movement of the elevator car 10.

[0038] The car frame 11 can be connected to the counterweight 41 via a rope 42 through a traction sheave 33. The car frame 11 can also be supported by a sliding device 27 on a guide rail 25 extending vertically within the shaft 20. The sliding device 27 may include a roller that rolls on the guide rail 25 or a sliding shoe that slides on the guide rail 25 as the car 10 moves up and down within the elevator shaft 20. The guide rail 25 can be attached to a side wall structure 21 within the elevator shaft 20 using a fastening bracket 26. As the car 10 moves up and down within the elevator shaft 20, the sliding device 27 holds the car 10 in a horizontal position. The counterweight 41 can be correspondingly supported on the guide rail, which is attached to the wall structure 21 of the shaft 20.

[0039] The elevator car 10 can transport people and / or goods between floors 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.

[0040] Figure 2 A side view of the elevator's mechanical braking system is shown.

[0041] The car 10 can be attached to a first side of the traction sheave 33, while the counterweight 41 can be attached to the opposite second side of the traction sheave 33. The lifting rope 42 can travel from the car 10 through the traction sheave 33 to the counterweight 41. The traction sheave 33 can be driven by an electric motor 32, which can be a permanent magnet synchronous motor. The mechanical brake 100 can include two electromagnetic brakes 110 and 120 acting on the traction sheave 33. The electromagnetic brakes 110 and 120 can be controlled by a mechanical brake controller 200. The electric motor 32 can be driven by a drive 31, such as a converter. The elevator, the drive 31, and the brake controller 200 can be controlled by a main controller 300. The traction sheave 33 can be equipped with a motion measuring device 130, which can be, for example, a tachometer.

[0042] As a first alternative, mechanical brakes 110 and 120 can be tested by braking tests according to the method in EP1701904.

[0043] The method in the EP patent includes the following steps.

[0044] A predefined test load is set to be applied to the elevator's drive mechanism. This can be done by loading a test load onto the elevator car whose weight is reliably known. The weight of the test load depends on the amount of overload the mechanical brakes need to withstand. When the mechanical brakes are required to withstand a 25% overload, or 125% of the load, the test load must be 75% of the elevator's nominal load. If the mechanical brakes are required to withstand a P% overload, the test load must be 50% + P%. Alternatively, the test load can be provided by the torque of the drive motor without additional weight in the car.

[0045] The motor torque is then increased until the car begins to move. The motor torque value that initiates the movement is measured and stored in memory. This torque value is represented as the first torque value.

[0046] Then close at least one mechanical brake.

[0047] Then, the empty elevator car is driven upwards with the first torque value.

[0048] Then check the movement of the car.

[0049] If movement of the car is detected, the at least one mechanical brake is considered defective.

[0050] As a second alternative, mechanical brakes 110 and 120 can be tested by braking tests according to the method in EP1915311.

[0051] The method in the EP patent includes the following steps.

[0052] When the elevator operation ends, only one mechanical brake engages, while the other mechanical brakes engage with a delay.

[0053] Monitor the elevator's movement and any slippage of the mechanical brake when it is engaged.

[0054] If mechanical brake slippage is detected in the previous step, the elevator is prevented from starting.

[0055] EP2774885B1 discloses a method for performing a balance check on an elevator. The balance check determines the elevator's counterweight difference. The counterweight difference is the difference between the weight of the empty elevator car and the elevator's counterweight.

[0056] The method in the EP patent includes the following steps.

[0057] Establish a power model for the elevator, which includes the power fed to the motor (PM), the power parameters of the motor, and the power parameters of the moving parts in the shaft (PK, PP, PFR, PCu, PFE).

[0058] Conduct elevator test runs.

[0059] Determine intermediate power values ​​for the car in the upward (PME, middle, upper) and downward (PME, middle, lower) directions, wherein the intermediate power values ​​include the power fed to the motor only when the car moves at a constant speed through the middle of the elevator car's travel path in the upward and downward directions.

[0060] Calculate the power difference between the intermediate power values ​​in the upward and downward directions.

[0061] The balance power difference (mB) is calculated based on the power difference between the intermediate power values ​​in the upward and downward directions.

[0062] Elevator balance checks can be performed using a simplified power model that includes the motor power (PM) fed to the motor, the motor's power parameters, and the power parameters (PK, PP, PFR, PCu, PFe) of the moving parts in the shaft. Using such a model, the behavior of the elevator system can be simplified to easily obtain the balance weight difference (the weight difference between the car and the counterweight).

[0063] The power model can be defined in the following ways:

[0064] PM = PK + PP + PFR + PCu + PFE

[0065] Where PM = power fed to the elevator, PK = kinetic power of the moving elevator components, PP = potential power of the moving elevator components, PFr = frictional loss of the elevator components, PCu = internal loss of the motor winding resistance, and PFe = internal iron loss of the motor.

[0066] The power model simplifies the elevator system by modeling the power flow in the system. Necessary information for balance checks can be retrieved through a test run in which the car is driven in at least one closed loop to the upper and lower ends of the car's travel path.

[0067] The power difference between the upward and downward directions of the car can be determined at a point where the elevator travels at a constant speed. This allows the kinetic power PK of the system to be neglected. Kinetic power PK = mi * v * a, where mi is the mass of the moving parts of the elevator system, v is the speed of the car, and a is the acceleration of the car. When the elevator is running at a constant speed, the acceleration of the car is zero.

[0068] Consider only the power difference in the upward and downward directions in the middle of the travel path. Apart from the car and counterweight, all moving elevator components are balanced in the middle of the travel path where the car is located next to the counterweight. The weight of these components can therefore be ignored in the middle of the travel path. These components include, for example, suspension ropes, hoisting ropes, or compensating ropes. Therefore, the remaining relevant components for balance checks are the car and counterweight, which are the basic weight components for performing the balance check.

[0069] Therefore, the power model can be greatly simplified. All acceleration-based components can be ignored. All components independent of the direction of travel, such as frictional losses and iron losses, will cancel each other out because the difference between the stated values ​​in the upward and downward directions is used in the calculation.

[0070] In the middle of the elevator car's travel path, the kinetic energy power PK is zero.

[0071] The power parameters of copper losses can be easily calculated from the motor current IM and the motor winding resistance RS (PCu = IM). 2 *RS). These copper losses can be subtracted from the motor input power by PME = PM - Pcu. PME represents the corrected motor power reduction due to copper losses in the windings.

[0072] The power model can therefore be simplified to the following model:

[0073] PME = PP + PFR + PFE

[0074] Then the difference between the motor's power values ​​in the upward and downward directions can be determined. Further assuming that frictional loss PFR and iron loss PFe are independent of the elevator's direction of travel, the difference between the power values ​​is:

[0075] PME (top) PME (bottom) = PP (top) PP (bottom)

[0076] Therefore, the power difference in the upward and downward directions depends only on the potential power parameter. The potential power parameter includes all elevator components that move vertically in the elevator shaft, such as the car, counterweight, hoisting ropes, suspension ropes, and compensating ropes.

[0077] Only for the middle of the car's travel path, where the elevator car is positioned next to the counterweight, i.e., at the same level, is the power difference considered. The weight of all moving elevator components other than the car and counterweight is balanced in the middle of the travel path. These other moving components are formed, for example, by hoisting ropes, suspension ropes, and compensating ropes. Therefore, only the weight of the car and counterweight is significant in the middle of the travel path.

[0078] The difference between the power values ​​in the middle of the travel path can then be calculated in the following way:

[0079] PME(middle, top)PME(middle, bottom)=mB*g*Vnom-mB*g*(-Vnom)

[0080] Where mB is the balance weight difference or balance of the elevator system (in kilograms), Vnom is the nominal speed of the elevator, and g is the acceleration due to gravity g = 9.81 m / s². 2 .

[0081] The balance weight difference mB can therefore be calculated using the following formula:

[0082] mB = (PME, middle, upper PME, middle, lower) / (2 * g * Vnom)

[0083] Therefore, the drive unit can calculate the elevator system balance at the midpoint of the shaft by calculating the motor current during uniform speed operation (with the copper loss of the winding removed) and dividing the difference by the denominator = 2 multiplied by g multiplied by the elevator's nominal speed.

[0084] Instead of using a single power value from the middle of the elevator shaft, the average of several test runs can be used. Then, the arithmetic mean of the test runs can be used.

[0085] Figure 3 A flowchart for testing the safety features of an elevator is shown.

[0086] Step 501 includes performing a balance check according to a predetermined schedule.

[0087] Step 502 includes comparing the results of the balance check with predetermined criteria.

[0088] Step 503 includes proceeding to step 505 if the balance meets a predetermined criterion, otherwise proceeding to step 504.

[0089] Step 504 includes preventing normal elevator operation.

[0090] Step 505 includes permitting the execution of a braking test.

[0091] 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 counterweights. The counterweight can be located on any side wall, either side wall, or the rear wall of the elevator shaft. The drive unit, motor, traction sheave, and mechanical brake can be located in the machine room or somewhere in the elevator shaft. The car guide rails can be located on opposite side walls or the rear wall of the shaft in a so-called rack-mounted elevator.

[0092] 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 the safety characteristics of an elevator, the elevator comprising a car (10), a counterweight (41), and a rope (42) extending from the car (10) through a traction pulley (33) to the counterweight (41), the method comprising: When the car is empty, upon request to perform a balance check, the car is driven to perform a test run, which includes at least one closed motion cycle to the upper and lower ends of the car's travel path in the elevator's upward and downward directions to perform a balance check on the elevator. as well as Based on the results of the balance check, the operation of the elevator can be adjusted and controlled, the adjustable control including: selectively performing one of the following operations based on comparing the results of the balance check with a predetermined standard: Prevent the elevator from operating normally. Operate the elevator according to the downgraded elevator operation, or Based on the test load calculated according to the results of the balance check, the elevator is operated to perform a braking test on the elevator's mechanical brake.

2. The method according to claim 1, wherein, The request to perform the balance check was generated by the remote entity.

3. The method according to claim 1, wherein, The request to perform a balance check is based on a predetermined schedule.

4. The method according to claim 1, wherein, The request to perform the balance check is based on a schedule.

5. The method of claim 3, further comprising preventing normal operation of the elevator in response to determining that the balance check has not been performed according to the predetermined schedule.

6. The method according to claim 1, wherein, The predetermined criteria are based on log values ​​collected during earlier testing periods.

7. The method according to claim 1, wherein, The ability to adjustably control the operation of the elevator includes operating the elevator to perform a braking test of the mechanical brake in response to determining that the result of the balance check meets the predetermined criteria.

8. The method according to claim 1, wherein, The balance error tolerance is used to determine whether the result of the balance check meets the predetermined criteria.

9. The method according to claim 1, wherein, The ability to adjustably control the operation of the elevator includes preventing normal elevator operation in response to determining that the result of the balance check does not meet the predetermined standard.

10. The method according to claim 1, wherein, The ability to adjustably control the operation of the elevator includes operating the elevator according to a degraded elevator operation in response to determining that the result of the balance check does not meet the predetermined criteria.

11. The method according to claim 10, wherein, Operating the elevator according to the degraded elevator operation includes reducing the maximum load on the car.

12. The method of claim 1, further comprising performing the balance check, which includes: A power model for the elevator is established, which includes the motor power fed to the elevator motor, the motor power parameters, and the power parameters of the moving parts in the elevator shaft. Perform a test run on the elevator. Determine the intermediate power values ​​for the elevator in the upward and downward directions. These intermediate power values ​​are defined as the motor power fed to the motor only when the car moves at a constant speed through the middle of its travel path in both the upward and downward directions. Calculate the power difference between the intermediate power values ​​in the upward and downward directions. The balance weight difference is calculated based on the power difference.

13. The method according to claim 1, wherein performing a braking test on the mechanical brake of the elevator includes performing a motor-assisted braking test on the mechanical brake.

14. The method according to claim 2, wherein, The remote entity is a cloud service or a remote server.

15. The method according to claim 1, wherein, Performing the balance check includes: In response to determining that the measured load of the car is not zero within a specific time period, the measured load is defined as a new calibration zero load, and Based on the new calibration zero load, the balance weight difference between the weight of the car and the weight of the counterweight when the car is empty is determined.

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