Method for determining the braking state of an elevator

Abstract

The application discloses a kind of judging methods of elevator brake state, including the following steps, determine brake normal operation, adjust the gap of brake shoe and brake wheel, paste strain gauge on the surface of brake shoe, and set collector collection frequency;Make elevator under different load run down to uniform speed state after power off, the collector collects time domain signal and analyzes, obtains several groups corresponding different load under the time interval t of elevator from brake power off to brake shoe contact brake wheel, and the contact time T of brake shoe and brake wheel;According to the time interval t from brake power off to brake shoe contact brake wheel, whether the distance of brake shoe and brake wheel changes is judged;According to the contact time T of recorded brake shoe and brake wheel, generate fitting curve, compare the contact time T of brake shoe and brake wheel when actual emergency brake of the elevator to be detected with fitting curve, and the working state and fault condition of brake can be judged, simple operation, lower cost, high accuracy.

Description

Technical Field

[0001] This invention relates to the field of elevator braking technology, and more specifically to a method for determining the braking state of an elevator. Background Technology

[0002] The elevator braking system is an important component in ensuring the safe operation of elevators. Most of the elevator's operation control and safety protection rely on the action of the braking system to stop the elevator and ensure its safe operation.

[0003] During the daily operation of elevators, if the stiffness of the brake spring in the elevator safety system buffer deteriorates, or if the gap between the brake shoe and the brake wheel is unreasonable, causing the brake's safety function to fail, it often leads to serious accidents such as elevator falls, overshooting, or shearing, posing unacceptable risks to elevator operation safety and a huge threat to the lives and property of passengers. Therefore, timely inspection and maintenance of the elevator braking system are necessary. Currently, domestic and international research on elevators often uses computer vision and pneumatic devices to determine the working status of elevator brakes, which is relatively cumbersome and costly to install.

[0004] Typically, elevator braking systems are friction brakes, utilizing a self-compressing spring to press friction pads against the brake wheel, thereby increasing friction between the pads and the wheel to stop the elevator. When the elevator power is cut off, the brake applies emergency braking, clamping the brake wheel and changing the geometry of the brake shoe's back. When the elevator stops, the brake shoe stops deforming. The braking state of the brake can be determined by observing the time it takes for the brake shoe to deform. This invention aims to provide a method for determining the working state of a brake based on the braking time. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a simple, reliable and low-cost method for determining the working state of a brake based on braking time.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] A method for determining the braking state of an elevator includes the following steps:

[0008] S1: Confirm that the brake is operating normally, adjust the gap between the brake shoe and the brake wheel, attach strain gauges to the surface of the brake shoe, and set the acquisition frequency of the data acquisition device.

[0009] S2: After the elevator runs downwards to a constant speed under different loads, the power is cut off. The collector collects and analyzes the time domain signal to obtain several sets of corresponding times t from the time the power is cut off to the time the brake shoe contacts the brake wheel under different loads, and the contact time T between the brake shoe and the brake wheel.

[0010] S3: Determine whether the distance between the brake shoe and the brake wheel has changed according to the time interval t from when the brake is de-energized to when the brake shoe contacts the brake wheel;

[0011] S4: Generate a fitting curve based on the recorded contact time T between the brake shoe and the brake wheel, and compare the contact time T between the brake shoe and the brake wheel during the actual emergency braking of the elevator to be detected with the fitting curve to determine the working state and fault condition of the brake.

[0012] Furthermore, in step S1, the gap between the brake shoe and the brake wheel is adjusted to 0.2 - 0.7 mm.

[0013] Furthermore, in step S1, the strain gauge is a BX120 - 3AA strain gauge, and the collector is a JINGYAN - SG04 collector.

[0014] Furthermore, in step S2, the different loads of the elevator include 0 load, rated load, 1.25 times the rated load, and N times the load, where 0 < N < 1.25 and N is not equal to 1.

[0015] Furthermore, in step S3, record the minimum and maximum values of the measured time interval t as the judgment interval, and determine whether the distance between the brake shoe and the brake wheel has changed.

[0016] Furthermore, if the time interval t is less than the minimum value of the judgment interval, the distance between the brake shoe and the brake wheel is too small; if the time interval t is greater than the maximum value of the judgment interval, the distance between the brake shoe and the brake wheel is too large.

[0017] Furthermore, in step S4, the method for generating the fitting curve includes the least squares method, Gauss elimination method, or cubic spline curve fitting method to obtain the fitting curve of the contact time T between the brake shoe and the brake wheel during emergency braking under normal operation of the brake.

[0018] Furthermore, if the contact time T between the brake shoe and the brake wheel during the actual emergency braking of the elevator to be detected deviates upward too much from the fitting curve, the braking torque is too small; if the contact time T between the brake shoe and the brake wheel during the actual emergency braking of the elevator to be detected deviates downward too much from the fitting curve, the braking torque is too large.

[0019] Compared with the prior art, the method for judging the braking state of the elevator provided by the present invention has the following beneficial effects:

[0020] This invention acquires time-domain signals by installing strain gauges on the brake shoes, obtaining the time interval from brake de-energization to brake shoe contact with the brake wheel and the contact time between the brake shoes and the brake wheel under different loads. The minimum and maximum values ​​of the measured time interval from brake de-energization to brake shoe contact with the brake wheel are used as judgment intervals to determine whether the distance between the brake shoes and the brake wheel has changed. A fitting curve is generated based on the contact time between the brake shoes and the brake wheel. By comparing the actual contact time between the brake shoes and the brake wheel during emergency braking of the elevator under test with the fitting curve, the working status and fault condition of the brake can be determined. The invention is simple to operate, low in cost, and highly accurate. Furthermore, since the data used to generate the fitting curve comes entirely from the elevator under test, the resulting fitting curve is highly specific and can accurately assess the elevator's operating status. Attached Figure Description

[0021] Figure 1 This is a flowchart of the steps for determining the elevator braking state in an embodiment of the present invention. Detailed Implementation

[0022] To clearly illustrate the objectives, technical solutions, and advantages of this invention, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this invention. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0023] This invention provides a method for determining the working state of a brake, such as... Figure 1 As shown, the method mainly includes the following steps:

[0024] S1. Confirm that the brake is operating normally, adjust the gap between the brake shoe and the brake wheel, attach strain gauges to the surface of the brake shoe, and set the acquisition frequency of the data acquisition device.

[0025] The specific steps are as follows:

[0026] S11: Adjust the gap between the brake shoes and the brake wheel according to the requirements of GB10060-88 Elevator Installation and Acceptance Standard. GB10060-88 stipulates that when the brake is released, both brake shoes should separate simultaneously, and the gap should not exceed 0.7mm, generally 0.2-0.7mm. In this embodiment, the adjusted gap between the brake shoes and the brake wheel is 0.7mm.

[0027] S12: Apply adhesive to the brake shoe to attach the strain gauge. Press the strain gauge with your finger until the adhesive cures and then release it, so that the strain gauge is fixedly attached to the surface of the brake shoe.

[0028] The adhesive is H-610 strain gauge adhesive, the strain gauge is BX120-3AA strain gauge, and the strain gauge is used to detect the deformation of the brake shoe.

[0029] S13: Apply insulating tape to the brake shoe at the position corresponding to the strain gauge lead wire to insulate the lead wire from the brake shoe. Weld a terminal to the free end of the lead wire. Use a multimeter to check if the resistance between the two leads of the strain gauge is good. If there are defects such as poor soldering, perform repair soldering.

[0030] S14: Connect the lead wire to the data acquisition instrument. In this embodiment, the data acquisition instrument is a JINGYAN-SG04 data acquisition instrument. Connect the lead wire to the end with the terminal block and connect it correctly to the data acquisition instrument. Adjust the data acquisition instrument to strain mode and set the acquisition frequency to 1000Hz.

[0031] S2. After the elevator runs downwards to a constant speed under different loads, the power is cut off. The data acquisition device collects and analyzes the time domain signal to obtain the time interval t from the power cut-off of the brake to the contact of the brake shoe with the brake wheel, and the contact time T between the brake shoe and the brake wheel.

[0032] Among them, the most dangerous elevator braking is to take emergency braking when it is going down. Emergency braking when going up is safer than emergency braking when going down. Therefore, the present invention uses the elevator to run down to a constant speed under different loads and then cuts off the power to obtain the data signal of emergency braking under normal operation of the elevator brake.

[0033] The collected time-domain signal is divided into two parts based on the elevator's braking time from start to stop. The first part is the time interval t from when the brake is de-energized to when the brake shoe contacts the brake wheel, i.e., the time when the brake shoe moves towards the brake wheel; the second part is the contact time T between the brake shoe and the brake wheel, i.e., the time when the brake engages and brakes the elevator.

[0034] Before contacting the brake wheel, the brake shoe is only driven by the brake arm, so its deformation is uniform and gradually increases. After contacting the brake wheel, the brake shoe is constrained by the brake wheel and a braking torque is applied at the same time. The increase in deformation decreases and more obvious fluctuations occur, which are obvious changes in the time domain diagram. This is used to distinguish the two time periods and obtain the corresponding time intervals.

[0035] Specifically:

[0036] S21: The elevator is unloaded and moves downwards to a constant speed, then the power is cut off; at the moment of power failure, the elevator brakes urgently. By analyzing the time domain signal collected by the JINGYAN-SG04 data acquisition instrument, the time interval t1 from the power failure of the brake to the contact of the brake shoe with the brake wheel, and the contact time T1 between the brake shoe and the brake wheel are obtained.

[0037] S22: Load the elevator with its rated load and run it downward until it reaches a uniform state, then cut off the power supply; at the moment of power cut-off, the elevator makes an emergency brake. By analyzing the time-domain signals collected by the JINGYAN-SG04 collector, obtain the time interval t2 from the moment the brake is powered off to when the brake shoe contacts the brake wheel, and the contact time T2 between the brake shoe and the brake wheel.

[0038] S23: Load the elevator with 1.25 times its rated load and run it downward until it reaches a uniform state, then cut off the power supply; at the moment of power cut-off, the elevator makes an emergency brake. By analyzing the time-domain signals collected by the JINGYAN-SG04 collector, obtain the time interval t3 from the moment the brake is powered off to when the brake shoe contacts the brake wheel, and the contact time T3 between the brake shoe and the brake wheel.

[0039] Among them, in accordance with the requirements of the Second Amendment of the "Rules for Elevator Supervision Inspection and Periodic Inspection - Traction and Forced Drive Elevators" TSGT7001-2009, a braking test at the rated speed with the car (passenger elevator) carrying 125% of the rated load shall be carried out during elevator inspection.

[0040] S24: Load the elevator with N times its rated load and run it downward until it reaches a uniform state, then cut off the power supply, where 0 < N < 1.25 and N is not equal to 1; at the moment of power cut-off, the elevator makes an emergency brake. By analyzing the time-domain signals collected by the JINGYAN-SG04 collector, obtain the time interval tn from the moment the brake is powered off to when the brake shoe contacts the brake wheel, and the contact time Tn between the brake shoe and the brake wheel.

[0041] S25: Repeat step S24 to obtain several sets of time intervals t from the moment the brake is powered off to when the brake shoe contacts the brake wheel and contact times T between the brake shoe and the brake wheel of the elevator under different load weights.

[0042] It should be noted that there is no strict requirement for the order of the above steps S21 - S25, and appropriate adjustments or replacements can be made to achieve the purpose of obtaining several sets of time intervals t from the moment the brake is powered off to when the brake shoe contacts the brake wheel and contact times T between the brake shoe and the brake wheel of the elevator under different load weights.

[0043] S3: Judge whether the distance between the brake shoe and the brake wheel has changed according to the time interval t from the moment the brake is powered off to when the brake shoe contacts the brake wheel;

[0044] For the time interval t from the moment the brake is powered off to when the brake shoe contacts the brake wheel, it is the time for the brake shoe to move closer to the brake wheel under the driving force of the brake arm. The distance between the brake shoe and the brake wheel is relatively small, so the change in the time interval t from the moment the brake is powered off to when the brake shoe contacts the brake wheel is also relatively small. Record the minimum and maximum values of the measured time interval t as the judgment interval for judging whether the distance between the brake shoe and the brake wheel has changed.

[0045] In actual testing, if the detected time interval t is less than the minimum value of the judgment interval, the distance between the brake shoe and the brake wheel is too small, and the brake shoe is prone to rubbing against the brake wheel during operation; if the detected time interval t is greater than the maximum value of the judgment interval, the distance between the brake shoe and the brake wheel is too large, the reaction time during braking will be longer, and there is a risk of untimely braking.

[0046] S4. Generate a fitting curve based on the recorded contact time T between the brake shoe and the brake wheel. Compare the fitting curve with the actual contact time T between the brake shoe and the brake wheel during emergency braking of the elevator under test to determine the working status and fault condition of the brake.

[0047] Curve fitting is performed on the contact time T between the brake shoe and the brake wheel. Methods for generating the fitted curve include least squares method, Gaussian elimination method, and cubic spline curve fitting. In this embodiment, due to its relatively small computational load and the near-uniform deceleration of the elevator's descent, the relationship between braking time and load is relatively linear, making fitting easier. Therefore, the least squares method is preferred for curve fitting. The horizontal and vertical axes are set as the car load and braking time, respectively, to obtain the fitted curve. This fitted curve is the fitted curve of the contact time T between the brake shoe and the brake wheel during emergency braking under normal brake operation.

[0048] During actual testing, the contact time T between the brake shoe and brake wheel during the actual emergency braking of the elevator under test is compared with the fitted curve to determine the working status of the brake and whether a fault has occurred. If the contact time T deviates too much upward from the fitted curve, the braking torque is too small, and there is a risk of failure to brake on time; if the contact time T deviates too much downward from the fitted curve, the braking torque is too large, which will accelerate the wear of the brake wheel and brake shoe and shorten the service life of the brake.

[0049] The above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A method for determining the braking state of an elevator, characterized in that, It includes the following steps: S1: Ensure the normal operation of the brake, adjust the gap between the brake shoe and the brake wheel, mount strain gauges on the surface of the brake shoe, and set the acquisition frequency of the collector; S2: Make the elevator run downward at different loads until it reaches a uniform speed and then cut off the power. The collector collects the time-domain signal and analyzes it to obtain several sets of corresponding times t from when the brake power is cut off to when the brake shoe contacts the brake wheel under different loads, and the contact time T between the brake shoe and the brake wheel; S3: Determine whether the distance between the brake shoe and the brake wheel has changed according to the time interval t from when the brake power is cut off to when the brake shoe contacts the brake wheel; S4: Generate a fitting curve based on the recorded contact time T between the brake shoe and the brake wheel, and compare the contact time T between the brake shoe and the brake wheel during the actual emergency braking of the elevator to be detected with the fitting curve to judge the working state and fault condition of the brake; 2. The method for determining the braking state of an elevator according to claim 1, characterized in that, In step S1, the gap between the brake shoe and the brake wheel is adjusted to 0.2 - 0.7 mm.

3. The method for determining the braking state of an elevator according to claim 1, characterized in that, In step S1, the strain gauge is a BX120 - 3AA strain gauge, and the collector is a JINGYAN - SG04 collector; 4. The method for determining the braking state of an elevator according to claim 1, characterized in that, In step S2, the different loads of the elevator include 0 load, rated load, 1.25 times the rated load, and N times the load, where 0 < N < 1.25 and N is not equal to 1; 5. The method for determining the braking state of an elevator according to claim 1, characterized in that, In step S3, record the minimum and maximum values of the measured time interval t as the judgment interval, and determine whether the distance between the brake shoe and the brake wheel has changed; 6. The method for determining the braking state of an elevator according to claim 5, characterized in that, If the time interval t is less than the minimum value of the judgment interval, the distance between the brake shoe and the brake wheel is too small; if the time interval t is greater than the maximum value of the judgment interval, the distance between the brake shoe and the brake wheel is too large; 7. The method for determining the braking state of an elevator according to claim 1, characterized in that, In step S4, the method for generating the fitting curve includes the least squares method, Gauss elimination method, or cubic spline curve fitting method to obtain the fitting curve of the contact time T between the brake shoe and the brake wheel during emergency braking under normal operation of the brake; 8. The method for determining the braking state of an elevator according to claim 7, characterized in that, If the contact time T between the brake shoe and the brake wheel during the actual emergency braking of the elevator to be detected deviates upward too much from the fitting curve, the braking torque is too small; if the contact time T between the brake shoe and the brake wheel during the actual emergency braking of the elevator to be detected deviates downward too much from the fitting curve, the braking torque is too large.

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