System for detecting abnormal conditions during elevator operation

Abstract

The invention relates to a method, system and computer program for monitoring the operation of a rope interconnecting a car and a counterweight of an elevator and detecting an abnormal operating condition during the drive of a traction sheave intended to move together with the car and the counterweight by means of said rope. The rope travels in its course from the car to the traction sheave via at least one pulley and in its course from the counterweight to the traction sheave via at least one pulley, wherein the rotation of said at least two pulleys is monitored by sensing their rotation. Then, these rotation data are analyzed in terms of a mutual correlation indicating a synchronous operation of the rope on either side of the traction sheave, and an abnormal condition is detected in consequence of detecting the absence of such a correlation.

Description

Technical Field

[0001] This invention relates to the field of elevator technology, and more specifically to a detection system for monitoring abnormal movement of an elevator car and / or counterweight. Background Technology

[0002] One of the most popular elevator designs remains the rope-driven elevator. In current versions of this type, the car is connected to a counterweight via suspension ropes that are guided in a loop on a traction sheave, which is driven by an electric motor to move the car up or down. The counterweight moves in the opposite direction, meaning that as the car moves down, the counterweight rises, and vice versa. The ropes can be round or flat. Regarding the counterweight, its weight is essentially the same as that of an empty car at 40% of its rated capacity. In other words, when the car is 40% full (on average), the counterweight and the car are perfectly balanced. This balance aims to conserve energy and ensure sufficient friction between the suspension ropes and the traction sheave. With equal loads on both sides of the sheave, only a small force is needed to tip the balance in one direction or another. In other words, the balance maintains a near-constant potential energy level throughout the system. The friction between the ropes and the traction sheave is crucial in this elevator. Under normal operating conditions, the friction between the rope and the traction sheave is large enough to ensure that the elevator moves up and down in a predictable and reliable manner when the motor operates the traction sheave.

[0003] If the car or counterweight gets stuck during its downward movement, a special abnormal situation may occur. This can happen, for example, due to a guide shoe malfunction. This is called "stalling." If the friction between the suspension rope and the traction sheave is high enough, slack rope can accumulate above the stuck object. This is due to further rotation of the running traction sheave to lift the main body located on the other side of the traction sheave along the required path. This slack in the suspension rope can cause inconvenience and even safety risks: for example, the loss of traction after the slack rope has accumulated on the counterweight side for a period of time can cause the elevator car to freefall, which could be due to the suspension rope becoming taut on the slack side or the elevator overspeed regulator and safety devices abruptly stopping the car—the former placing a huge load on the suspension rope, and both causing great inconvenience and even danger to the passengers in the car. Another example of stalling is when the counterweight or elevator car descends onto the buffer at the bottom of the shaft while the hoist continues to lift the opposite side—causing the main body on the opposite side to collide with the shaft ceiling. In summary, "stall" refers to a situation where the counterweight or elevator car does not continue to move downwards, which is what the hoist should aim to achieve through rotation. In this case, the elevator should be stopped as soon as possible after such a stall is detected.

[0004] In existing technologies, stall detection is based on monitoring the current demand of the hoisting mechanism of the traction sheave or the torque generated by the elevator hoisting mechanism. To this end, EP 2 865 629 B1 by the same applicant discloses such a solution. When a rapid change in torque is detected, a stall condition is suspected. However, a drawback of these solutions is that an indirect threshold is required to characterize the situation as an anomalous condition. Whether stall conditions are identified by motor current or torque, both parameters do indeed have values ​​under normal operating conditions. Therefore, the threshold must be defined by the magnitude of its value to characterize situations exceeding this normal range.

[0005] Therefore, the object of the present invention is to show a direct and more reliable method and system for monitoring elevator ropes and detecting stall conditions. Summary of the Invention

[0006] The basic idea of ​​this invention is to monitor and detect stall conditions by sensing the operation of at least two pulleys that guide the suspension rope in the hoistway, one pulley being located on the elevator car and the other not positioned relative to the car. The pulley not on the car can be a drive pulley or a pulley located on the counterweight. The pulley at the car (through which the suspension rope runs) should rotate at the same circumferential speed as any other pulley through which the suspension rope runs. The monitored pulley is equipped with a sensing system to detect its rotation. When these sensing data are received from the pulley sensors at the car and counterweight, the rope travel on both sides of the traction sheave can be evaluated and compared with each other. This travel data of the pulleys indeed indicates whether the compared pulleys have delivered the same length of rope over those distances indicating the correct travel of both the car and the counterweight. Once a discrepancy is found between these rotation data of the pulleys, an anomaly can be suspected. The discrepancy in the rotation of the sensor-equipped pulleys can be calculated based on the characteristics of each pulley. The sensing system conveniently includes a speed sensor, such as an encoder, which transmits speed data to a control unit that processes the data. If the pulley's size data is stored in the control unit's memory, various other information, such as the pulley's rotational distance over time, can be obtained from it.

[0007] Additionally, this analysis can be enhanced by including rotational data from the traction sheave itself or data from the machine driving the traction sheave. Such data could include the rotational speed of the traction sheave, its power consumption, or its torque.

[0008] When the elevator operates under the command of the drive unit to move the car or counterweight in the upward or downward direction, the movement of the car and counterweight can be determined by the output of a sensing system in the pulleys of the car and counterweight. Since these pulleys move simultaneously while the elevator is running, their rotational data can be used to monitor for stall. If one pulley stops moving or slows down while the other continues to move, it indicates that a stall has occurred.

[0009] Alternatively, a limit value indicating the maximum permissible speed difference can be set, such that once this limit is exceeded, an emergency situation can be defined and the elevator can be stopped. Therefore, the elevator drive can be disabled by switching the elevator to fault mode.

[0010] Therefore, an advantage of the invention is that stall conditions can be identified by making the car and counterweight independent of each other and independent of the operation of the hoist. In other words, an advantage of the invention is that it can detect stall conditions in situations where conventional methods simply cannot solve the problem, such as by implementing torque or current thresholds through a single entity (i.e., the traction sheave of the motor).

[0011] Furthermore, when handling stall control according to the present invention, elevator designers have greater freedom in selecting frictional characteristics for the ropes and traction sheaves. This can even provide better functionality.

[0012] Another advantage of this invention is that it provides better passenger safety. When the elevator car begins to stall, meaning it is temporarily stopped for a short period due to an undesirable defect, the car will freefall for a short distance until the slack in the ropes is eliminated and the ropes are tightened again. This inevitably causes a shock to passengers, which is not only uncomfortable but can also be dangerous. With this invention, stalling can be detected more quickly, allowing the elevator to be stopped before dangerous rope slack occurs. This prevents risks or inconveniences for passengers in the elevator car. Correspondingly, a stalling condition in the counterweight can cause risks or inconveniences.

[0013] This invention applies to all elevators where there is a risk of the elevator car or counterweight being pulled upwards independently of other components. It is further applicable to all elevators with traction sheaves, relating to suspension systems including common twisted-pair steel wire ropes, high-friction coated ropes, toothed belts, etc. When a stall is suspected, the elevator can be stopped or an alarm can be triggered.

[0014] According to the present invention, the following options exist for implementing the monitoring of the operating speed of the suspension rope:

[0015] The rotational speed is measured by a sensor using one or more of the following:

[0016] Steering pulley

[0017] Roller guide shoe or

[0018] The overspeed adjuster pulley on the car side where the suspension rope is located, and

[0019] The rotational speed is measured by a sensor using one or more of the following:

[0020] Steering pulley

[0021] Roller guide shoe or

[0022] The overspeed adjuster pulley on the counterweight side of the suspension rope.

[0023] In addition, a motor encoder sensor that measures the rotational speed of the traction rope sheave can be added to further include that speed for speed comparison.

[0024] Suitablely, the speed difference detection between the steering pulley and the traction sheave described above can operate in parallel with a slack rope detection system present in the rope end, such as the system shown in document WO 2007 / 144456. In such a system, a detector is used to sense the tensile stress in the rope. The most feasible system can then be used to detect counterweight jamming by detecting slack rope at the counterweight-side end and car jamming by detecting the speed difference between the car pulley and the traction sheave. Attached Figure Description

[0025] The invention will now be described in more detail with reference to the accompanying drawings. In which, Figure 1 The inventive concept is shown. Detailed Implementation

[0026] The elevator system shown includes an elevator car 10 suspended by a rope 13, which is guided on a traction sheave 14 to reach and suspend a counterweight 12. The rope is guided on pulleys 16 and 17, both belonging to the elevator car, and another pulley 18, belonging to the counterweight. Each pulley 16, 17, and 18 inherently exhibits a rotation associated with the movement as the rope moves to raise or lower the car. This means that each pulley 16, 17, and 18 exhibits a characteristic angular distance each time the rope travels on a pulley. In other words, the speed of pulley 16 is v1, the speed of pulley 17 is v2, and the speed of pulley 18 is v3. Although depending on the size of the individual pulleys, the individual travel values ​​can be compared between all these pulleys, so that in normal operation, specific data must be obtained from each pulley to understand the correct movement of the rope. This means that, assuming all pulleys—pulley one, pulley two, and pulley three—are of the same size, all pulleys must have the same speed and the same rotation angle distance, provided the elevator is operating correctly. A stall condition can be identified once the match between the pulley speeds or rotation distances can no longer be determined, indicating that the car or counterweight is not moving forward freely.

[0027] Therefore, an emergency can be triggered by activating an alarm or even by stopping the elevator.

[0028] At the very least, the rotation of the traction sheave 14 can be included in the comparison process by assessing whether the current required to add to its torque or energy consumption is necessary for normal operation.

[0029] Figure Labels

[0030] 10 elevator cars

[0031] 12 counterweights

[0032] 13 ropes

[0033] 14 traction rope reel

[0034] 16 pulleys one

[0035] 17 Pulley Two

[0036] 18 pulleys

Claims

1. A method for monitoring the operation of a rope (13) interconnecting a car (10) and a counterweight (12) of an elevator and detecting an abnormal operating condition during driving of a drive pulley (14) intended to move together with the car and the counterweight by means of the rope, wherein, The rope (13) travels along its path from the car (10) to the drive pulley (14) via at least one steering pulley (16, 17) and along its path from the counterweight (12) to the drive pulley (14) via at least one steering pulley (18). The feature is that the rotation of at least two of the pulleys (14, 16, 17; 18) is monitored by sensing their rotation, wherein rotation data is analyzed taking into account the mutual correlation of the unobstructed movement of the car (10), and an anomaly is detected when the absence of such correlation is detected, wherein a loose rope detection system is provided for the counterweight side terminal, which senses the tensile tension in the rope by a detector to detect counterweight jamming.

2. The method according to claim 1, characterized in that In response to an anomalous difference in the relative rotation data, the elevator operation is stopped.

3. The method according to claim 1 or 2, characterized in that It also includes issuing alarms in response to detected abnormal operating conditions.

4. A computer-readable medium comprising a computer program adapted to perform the method according to any one of claims 1-3 on a data processing system.

5. A system for monitoring the operation of a rope (13) connecting a car (10) and a counterweight (12) of an elevator, and for detecting abnormal operating conditions during the driving of a drive pulley (14) intended to move together with the car and the counterweight via said rope, the system comprising - At least one steering pulley (16, 17), a drive pulley (14), and at least one steering pulley (18) connected to the car are connected to the counterweight, wherein at least two pulleys (14, 16, 17, 18) are each equipped with a sensor to sense their rotation. - The control unit is configured to receive sensor data and analyze the sensor data by monitoring cross-correlation, which indicates the unobstructed movement of the car (10). - A loose rope detection system for the counterweight side end, which detects counterweight jamming by sensing the tensile tension in the rope through a detector.

6. The system of claim 5, wherein, The system is configured to stop elevator operation in response to the detection of abnormal differences in cross-correlation.

7. The system of claim 5 or 6, wherein, The system is configured to issue an alert in response to abnormal differences in detected cross-correlation.

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