Method and system for testing brakes of an elevator hoist

Abstract

The invention relates to a method of testing the hoist machine (10) brakes (7, 7') of an elevator (100) with a preselected test load TL. The method comprises: confirming an empty elevator car (2) in a test position S test ; obtaining information of the elevator balance B; obtaining information of the elevator friction Fr at the test position S test ; determining a required test torque T M of the hoist machine motor (5) based on the test load TL, the balance B and the friction Fr; opening one of the brakes (7, 7') while keeping the rest of the brakes engaged in a braking position; applying a torque with the motor (5) up to at most the required test torque T M ; measuring the movement of the elevator car and if the movement of the elevator car is detected, generating a signal indicating the degraded state of one or more hoist machine brakes.

Description

TECHNICAL FIELD

[0001] The invention relates to a method for testing an elevator hoisting machine brake and a system for implementing the method. In general, the invention relates to ensuring sufficient braking force of a hoisting machine brake. BACKGROUND

[0002] Elevators have an electromechanical hoisting machine brake as a safety device to apply a braking force to the traction sheave or rotating shaft of the elevator hoisting machine. There are usually at least two independent brake units, for example two, three or four units. Their size should be such that an overloaded elevator car stops and remains stationary. If one brake unit fails, the remaining brake units should still stop and hold the elevator car with an appropriate safety margin for safety reasons.

[0003] Due to its properties as an elevator safety device, the operating condition of the hoisting machine brake should be confirmed.

[0004] A confirmation method is disclosed in EP 1915311 B1. According to the method, only one holding brake of the elevator hoisting machine is engaged at the end of the elevator run, and the motor torque is removed. If the traction sheave starts to move due to the effect of gravity, the holding brake is considered to have failed.

[0005] There is a need to improve the testing method to accurately test the brake over its entire working range. SUMMARY

[0006] The object of the invention is to introduce a method that enables sufficient testing of the braking effect, in particular the braking torque of an elevator hoisting machine brake, by using a test load with improved accuracy.

[0007] It is advantageous to establish the test load by supplementing the load caused by elevator unbalance with an auxiliary motor torque of the elevator hoisting machine.

[0008] The auxiliary motor torque comprises components selected to compensate for the imperfections of a real-life elevator system. Thus, the auxiliary motor torque provides an accurate test of the hoisting machine brake.

[0009] The object is to introduce a solution by which one or more of the above-mentioned problems of the prior art and / or the drawbacks discussed or suggested elsewhere in the description can be solved. The object is especially to introduce a solution by which the testing of a hoisting machine brake can be accurately and simply provided.

[0010] A new method is presented for testing an elevator hoisting machine brake with a preselected test load TL, which method comprises:

[0011] - confirming an empty elevator car located in a test position Stest,

[0012] obtaining information of an elevator balance B,

[0013] obtaining information of a friction Fr of the elevator at a test position Stest,

[0014] determining a required test torque T of the hoisting motor based on the test load TL, the balance B and the friction Fr M (an auxiliary motor torque),

[0015] opening one of the hoisting brakes while keeping the remaining brakes engaged in a braking position,

[0016] applying a torque with the motor of the elevator hoisting machine up to at most the required test torque T M ,

[0017] measuring a movement of the elevator car, and

[0018] generating a signal indicating a degraded condition of one or more of the hoisting brakes upon detecting a movement of the elevator car.

[0019] Preferred further details of the method are outlined in the following.

[0020] According to some embodiments, the method is repeated for each hoisting brake by keeping each hoisting brake open while keeping the remaining brakes engaged in a braking position.

[0021] According to some embodiments, the test load TL corresponds to a preselected overload, which is indicated by a factor OL as follows: TL = OL * N, where N is the rated load N of the elevator car and OL is preferably selected from the range of 101%... 130%, more preferably 105%... 120%, most preferably OL = 110%.

[0022] Preferably, the elevator comprises:

[0023] an elevator car, a counterweight and an elevator rope movably arranged within a hoistway, wherein the elevator car and the counterweight are at least partially supported by the elevator rope; and

[0024] a hoisting machine comprising:

[0025] a motor and a traction sheave connected to the motor for moving the elevator car and the counterweight via the elevator rope; and

[0026] at least two brakes arranged to stop and prevent movement of the elevator car when the elevator is stopped.

[0027] According to some embodiments, the movement of the elevator car is measured by measuring the rotation of the elevator hoisting machine, preferably the movement of the motor or of a traction sheave connected to the motor and supporting the elevator ropes for moving the elevator car. The movement information of the elevator car of the drive unit can be obtained from a rotation sensor or resolver connected to the motor or from a positioning device connected to the elevator car or located in the hoistway.

[0028] Preferably, the hoisting machine motor is a synchronous permanent magnet motor.

[0029] A new system for implementing the method of the application is also proposed. The system can be part of an elevator drive unit or provided separately. The system can be implemented in hardware and / or software modules of an elevator drive unit and / or in an elevator maintenance or installation tool for installing or servicing an elevator.

[0030] According to one embodiment, the elevator drive unit comprises an elevator hoisting motor, preferably a synchronous permanent magnet motor, and a frequency converter configured to drive the motor.

[0031] According to some embodiments, the system has an input for the motor current fed to the motor and an input for the car position, which inputs are connectable to an elevator drive unit. BRIEF DESCRIPTION OF DRAWINGS

[0032] In the following, the application will be described in more detail by way of example and with reference to the accompanying drawings, in which:

[0033] Figure 1 An embodiment of an elevator system comprising at least two brakes is schematically shown,

[0034] Figure 2 An example of the preferred method is shown, and

[0035] Figure 3 A substantially constant relationship between the motor current and the motor torque in a synchronous permanent magnet motor is shown. DETAILED DESCRIPTION

[0036] Figure 1 An elevator 100 is shown, which has an elevator car 2 and a counterweight 3 movably arranged inside a hoistway 1. The elevator car 2 and the counterweight 3 are supported at least partly by means of elevator ropes 4. The elevator car 2 and the counterweight 3 are driven by a motor 5 of a hoisting machine 10. In addition to the motor, the hoisting machine comprises a traction sheave 6 connected to the motor for moving the elevator car and the counterweight via the elevator ropes. The hoisting machine 10 comprises at least two brakes 7, 7', for example two, three or four brakes 7, 7', which are arranged to stop and prevent the movement of the elevator car when the elevator is stopped.

[0037] The traction sheave 6 can be integrated into the motor 5 or connected to the motor 5 in a suitable manner. Preferably, the motor 5 is a synchronous permanent magnet motor. Preferably, the brakes 7, 7' are electromagnetic brakes, arranged, for example, to press the brake shoe against a braking surface connected to or separated from the traction sheave 6.

[0038] like Figure 1 As shown, the drive unit 15 can be used to control the movement of the motor. Figure 1 As shown, the braking control system used to test the adequacy of the braking effect can be implemented in the hardware and / or software module 16 of the elevator drive unit 15, and optionally in the elevator maintenance or installation tool 17. Preferably, the system has inputs for feeding motor current to the motor 5 and inputs for the position of the car 2, which can be connected to the elevator drive unit 15.

[0039] like Figure 2 As shown, a method is provided for testing the brake 7.7' of the hoist 10 using a pre-selected test load TL. The system used to implement the method for testing the adequacy of the braking effect can be part of the elevator drive unit 15, or provided separately, and can be... Figure 1 It is part of the elevator system 100.

[0040] The test load TL can be selected based on the environment of the specific elevator facility. Preferably, the test load TL corresponds to a pre-selected overload, which is represented by a factor OL. Preferably, the overload is selected as OL = 110%, that is, the load is 10% higher than the rated load N of the elevator car.

[0041] TL=OL*N, preferably TL=110%*N (1)

[0042] The method includes confirming that the empty elevator car 2 is located at the test position Stest, such as the lowest or highest floor in the elevator shaft 1.

[0043] The method also includes collecting information on the elevator's balance B and friction Fr at the test location Stest.

[0044] Balance B can be a parameter registered in the elevator control system. Balance B can also be checked, for example, from equation (5) in WO2014135408 A1, which is called the balance weight m. B In the equation m B =[(P ME，mid，up -P ME，mid，dn ) / 2*g*v nom In ], m B v represents the difference in equilibrium weight in kilograms. nom The value represents the elevator's nominal speed, and g represents the acceleration due to gravity, 9.81 m / s². 2According to the equation, during constant speed operation, the motor current is determined by which the upward and downward direction copper losses are removed, and the difference is divided by the nominal speed and g, and the balance at the middle position of the shaft is obtained.

[0045] The balance check determines the balance weight difference of the elevator. The balance weight difference is the difference between the weight of the empty elevator car 2 and the weight of the elevator counterweight 3. Furthermore, the balance B can be the nominal balance B N , or it can also contain a position-dependent non-compensation term U in addition to the nominal balance B N

[0046] B = B N + U (2)

[0047] The non-compensation is a position-dependent compensation error caused by moving parts, such as the suspension ropes, hoisting ropes or compensation ropes of the elevator. It can be considered to vary linearly as a function of the elevator car position s, so that, for example, the nominal balance B N is reached in the middle of the elevator shaft 1. Typically, this test method can be implemented at any floor or test position, but if the method is implemented at the top and / or top floor of the elevator shaft, no compensation is required.

[0048] The friction Fr can be measured by moving the elevator car 2 very slowly up and down at the test position Stest and measuring the motor drive current in both directions. The force / current generated by the shaft friction (friction of the moving parts in the elevator shaft) is calculated from (upward current - downward current) / 2.

[0049] Since the aforementioned components have been determined, the test torque TM of the elevator hoisting motor 5, in other words the auxiliary test torque, is determined on the basis of said components TL, B and Fr:

[0050] TM→ (OL - B) * N + Fr (3)

[0051] In the above equation 3, the balance B is expressed as a percentage of the nominal load N.

[0052] The hoisting machine brakes 7, 7' are tested by opening one brake at a time while keeping the rest of the brakes engaged, i.e. in their braking position. Then a torque is applied, for example the torque is raised up to the required test torque T M ​At the same time the movement state of the hoist 10 is observed, for example the movement of the traction sheave 6 is observed. If a rotation of the hoist 10 is observed, a signal is generated which indicates an operational anomaly of the brake or brake system. This indication, preferably with a more precise case analysis of at least one of the following: failed brake combination; statistical information, which torque values lead to a rotation, etc., can be transmitted to, for example, a service technician, a remote monitoring center and / or a cloud network for diagnosing brake problems and scheduling maintenance.

[0053] Preferably, the motor current I M corresponding to the required test torque T M is determined as described below. All hoist brakes 7, 7’ are opened, the hoist motor 5 is activated and the motor current Ig required to keep the elevator car 2 stationary with the brakes open is recorded. Then, the required test current I M can be determined from the current Ig, the test load TL, the balance B and the friction Fr as shown below:

[0054] I M → I g * [(OL-B)*N / (B*N-F r )-1] (4)

[0055] This equation can be used when there is a linear relationship between the motor current and the motor torque. This is especially the case when the hoist motor is a synchronous permanent magnet motor. Figure 3 An example related to a synchronous permanent magnet motor is shown, where the linear relationship is represented by a parameter k between the motor current I and the motor torque T, i.e. a change in the motor current ΔI will cause a change in the motor output torque ΔT. Optionally, the ratio of current to torque can be learned by the drive.

[0056] Then, up to the current I of the motor current I M is provided to the winding of the hoist motor 5 to produce the required auxiliary test torque T M ; thereafter, for the other brakes of the hoist 10, the test procedure continues in the same manner as for the disclosure above.

[0057] According to the first example, the method is implemented in the following cases:

[0058] - rated load N = 1000 kg, overload factor OL = 110%

[0059] -> preselected test load TL = 1100 kg

[0060] - balance B = 50%

[0061] - the elevator car 2 is empty

[0062] - test position test S test - without compensation error U

[0063] - shaft friction Fr = 0

[0064] - parameter k = constant.

[0065] The brake test load to be verified is: 110% x 1000 kg - 50% x 1000 kg = 600 kg. If one brake group 7, 7' fails, the remaining brake groups should be able to hold and decelerate 110% of the load. The drive unit 15 measures the current Ig required to hold the car 2 stationary when the brakes are not engaged. This current Ig represents the force to hold 500 kg stationary. Then, one brake group remains open and the other brake groups are closed. The drive unit 15 increases the current of the motor by 0.1 x Ig, which corresponds to the required test force.

[0066] Required test force <-> I M = 1.2 x Ig

[0067] Required motor assistance force = 600 kg - 500 kg = 100 kg <-> 0.2 x Ig

[0068] I M -> I g * [(OL - B) * N / (B * N - F r - 1] <-> I g * [(110 - 50) * 1000 / (0.5 * 1000 - 1] = I g * 0.2

[0069] If no movement on the motor traction sheave 6 is detected when the test torque is applied, the test is passed. The remaining brake group combinations are tested according to the same procedure.

[0070] According to a second example, the method is implemented in the following cases:

[0071] - rated load N = 1000 kg, overload factor OL = 110%

[0072] -> preselected test load TL = 1100 kg

[0073] - balance B = 40%

[0074] - elevator car 2 is empty

[0075] - test position test S test - without compensation error U

[0076] - shaft friction Fr = 10 kg

[0077] - parameter k = constant

[0078] The brake test load to be verified is: 110% x 1000 kg - 40% x 1000 kg = 700 kg. If one brake group 7, 7' fails, the remaining brake groups should be able to hold and decelerate 110% of the load. The drive unit 15 measures the current Ig required to hold the car 2 stationary when the brakes are not engaged. This current Ig represents the force to hold 400 kg stationary minus the friction force Fr of 10 kg. Then, one brake group remains open and the other brake groups are closed. The drive unit 15 increases the current of the motor by 0.41 x Ig, which corresponds to the required test force.

[0079] Required test force < I M = 1.79 x Ig

[0080] Required motor assistance force = 700 kg - 390 kg = 310 kg < 0.79 x Ig

[0081] I M → I g * [(OL-B) * N / (B * N - F r - 1] <→ I g * [(110 - 40) * 1000 / (0.4 * 1000 - 10) - 1] = I g * 0.79

[0082] If no movement of the elevator car is detected when the test torque is applied, the test is passed. The remaining brake group combinations are tested according to the same procedure.

[0083] In this application, several details of the arrangement have been given preferably. This means that they are preferred, however they should not be understood as being essential, since the arrangement can also be implemented without them.

[0084] It should be understood that the above description and the drawings are only intended to illustrate the present application. It will be apparent to a person skilled in the art that changes and modifications can be made to the present application without departing from the scope of the present application.

Claims

1. A method of testing an elevator (100) hoist machine (10) brake (7, 7') with a preselected test load TL, comprising: - confirming the presence of the empty elevator car (2) in the test position S test , - obtaining information of the elevator balance B, - obtaining information of the friction Fr of the elevator at the test position S test , - determining a required test torque T of the hoist motor (5) based on the test load TL, the balance B and the friction Fr M , - opening one of the brakes (7, 7') while keeping the rest of the brakes engaged in the braking position, - applying up to the required test torque T with the hoist motor (5) a torque of at most M Tmax. - measuring the movement of the elevator car, and - generating a signal indicating the degraded state of one or more hoist brakes if movement of the elevator car is detected.

2. The method of claim 1, wherein, The method is repeated for each hoist brake (7, 7') by keeping it open while keeping the rest of the brakes engaged in the braking position.

3. The method of claim 1, wherein, The test load TL corresponds to a preselected overload, which is represented by a factor OL as follows: TL = OL * N, where N is the rated load N of the elevator car (2).

4. The method of claim 3, wherein, OL is selected from the range 101%... 130%.

5. The method of claim 4, wherein, OL is selected from the range 105%... 120%.

6. The method of claim 5, wherein, OL = 110%.

7. The method of any one of claims 1 to 6, wherein, The elevator (100) comprises: - an elevator car (2), a counterweight (3) and an elevator rope (4) movably arranged inside a hoistway (1), wherein the elevator car and the counterweight are supported at least partly by means of the elevator rope; and - a hoist machine (10) comprising: - a hoist machine motor (5) and a traction sheave (6) connected to the motor for moving the elevator car and the counterweight via the elevator rope; and - at least two brakes (7, 7') arranged to stop the elevator car and prevent the elevator car from moving when the elevator is stopped.

8. The method of any one of claims 1 to 6, wherein, Measuring the movement of the elevator car (2) is achieved by measuring the rotation of the elevator hoist machine (10).

9. The method of claim 8, wherein, Measuring the movement of the elevator car (2) is achieved by measuring the movement of the motor (5) or the traction sheave (6) for moving the elevator car via the elevator rope.

10. The method of any one of claims 1 to 6, wherein, The movement information of the elevator car is obtained from a rotation sensor or resolver connected to the motor; or from a positioning device connected to the elevator car or located in the hoistway.

11. The method of any one of claims 1 to 6, wherein, The hoist machine motor (5) is a synchronous permanent magnet motor.

12. A system for implementing the method according to any of the preceding claims.

13. The system according to claim 12, which is part of an elevator drive unit (15).

14. The system of claim 13, wherein, The system is implemented in hardware and / or software modules (16) of the elevator drive unit (15) and / or in an elevator maintenance or installation tool (17).

15. The system of claim 13 or 14, wherein, The elevator drive unit (15) comprises an elevator hoist machine motor (5) and a frequency converter configured to drive the motor.

16. The system of claim 15, wherein, The elevator hoist motor is a synchronous permanent magnet motor.

17. The system of claim 13 or 14, wherein, The system has an input for the motor current fed to the hoist machine motor (5) and an input for the car (2) position s, which inputs are connectable to the elevator drive unit (15).

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