WO2010098756A1

WO2010098756A1 - Elevator inspection system

Info

Publication number: WO2010098756A1
Application number: PCT/US2009/035245
Authority: WO
Inventors: Ryuji Onoda; Hirohumi Otoyo
Original assignee: Otis Elevator Co
Current assignee: Otis Elevator Co
Priority date: 2009-02-26
Filing date: 2009-02-26
Publication date: 2010-09-02
Anticipated expiration: 2011-08-26

Abstract

A device for detecting defects in a moving elevator traction member includes an eddy current sensor configured to be arranged adjacent the moving traction member, and a controller configured to calibrate the sensor and interpret signals received from the sensor as the traction member moves by the sensor.

Description

U72 500-72

ELEVATOR INSPECTION SYSTEM

BACKGROUND

The methods and devices disclosed herein relate to elevator inspection systems, in particular, systems for inspecting elevator traction members for defects.

A typical traction elevator system includes an elevator car and a counterweight, each suspended on opposite ends of traction members, such as belts or ropes (also known as cables), in an elevator hoistway. The elevator car may be attached to a car frame to which the traction members are attached. The elevator car and frame are pulled up and let down the hoistway by the traction members, which are looped around a sheave driven by a hoist machine. The drive sheave and hoist machine are commonly located in the machine room near the top of the hoistway. Different roping arrangements may be employed in elevator systems to increase mechanical advantage, and thereby increase the duty of the elevator car without increasing the number or size of the traction members. For example, in an elevator system employing a 2:1 roping arrangement, instead of terminating at the car and counterweight, the traction members loop around idler sheaves on one or both of the car (or car frame) and the counterweight and terminate toward the top of the hoistway.

Elevator traction members may be made up of one or more steel ropes. Each steel rope typically includes multiple cords which, in turn, include a number of strands made up of individual steel wires. Deterioration of a multi-strand or multi-cord elevator rope may adversely affect the tensile strength of the rope. The tensile strength of a rope is dependent upon various parameters including cross-sectional area. When portions of a steel rope crack, tear or plastically deform, the effective tension-bearing cross-sectional area of the rope is reduced and thereby portions of the rope may be disabled or weakened as load bearing members. Elevator rope deterioration can occur through normal wear and tear, impact, fatigue, and corrosion.

Because elevator ropes are relatively long and are made up of many individual wires and strands, it is impractical to visually inspect the rope. A principal problem with visual inspection is that only a small fraction of the tension-bearing cross- sectional area on the outer surface of the rope can be seen. Also, it is difficult to visually inspect an entire length of rope installed in an elevator system. Finally, visual inspections are commonly conducted at relatively large time intervals, such as six or twelve months, which increases the risk of unsafe rope deterioration between inspections. It has therefore been common to substantially overdesign elevator ropes to allow for a large margin of deterioration without a large risk of failure.

To save on material and labor costs from rope overdesign and visual inspection, and to increase inspection quality, various inspection devices have been proposed for detecting defects in elevator ropes. For example, resistance based inspection

(RBI) and magnetic flux leakage are two common methods used to detect defects in elevator ropes. However, both RBI and magnetic flux leakage have disadvantages. RBI requires applying an electrical current to the elevator rope to measure the resistance from end-to-end. In some applications, such as where the rope is unshielded by an electrical insulator, it may be undesirable to run an electrical current throughout the elevator rope.

Magnetic flux leakage detection devices require permanent magnets, which may significantly increase the cost of the device, and may only be used to measure traction members moving at relatively slow speeds. The speed limitation of magnetic flux detection may completely foreclose inspection of some elevator systems, or require taking the elevator out of service for a special test run at lower speeds.

In light of the foregoing, the present invention aims to resolve one or more of the aforementioned issues that can affect elevator systems.

SUMMARY A device for detecting defects in a moving elevator traction member includes an eddy current sensor configured to be arranged adjacent the moving traction member, and a controller configured to calibrate the sensor and interpret signals received from the sensor as the traction member moves by the sensor.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the present invention will become apparent from the following description, appended claims, and the accompanying exemplary embodiments shown in the drawings, which are hereafter briefly described.

FIG. 1 is a perspective view of a traction elevator system. FIGS. 2A and 2B are orthogonal views of an embodiment of a traction member inspection device according to the present invention.

FIG. 3 is a schematic view of the inspection device of FIGS. 2A and 2B.

FIG. 4 is a schematic view of the inspection device of FIGS. 2A-3 connected to an output device.

FIG. 5A is a schematic view of the elevator system of FIG. 1 including the inspection device of FIGS. 2A-4.

FIG. 5B is a schematic view of the inspection device of FIGS. 2A-5A communicating traction member defects to an elevator system controller. FIG. 6 is a schematic view of an embodiment of an elevator system according to the present invention, which elevator system includes two inspection devices arranged in series in the elevator system of FIG. 1.

FIG. 7 is an orthogonal view of multiple inspection devices employed in parallel to inspect multiple traction members. DETAILED DESCRIPTION

Efforts have been made throughout the drawings to use the same or similar reference numerals for the same or like components.

FIG. 1 is a perspective view of elevator system 10 including car 12, counterweight 14, traction members 16, such as ropes or belts (hereinafter collectively "ropes 16"), drive machine 18, sometimes referred to as a hoist machine, and hoistway 20.

In FIG. 1, car 12 and counterweight 14 are connected to drive machine 18 by ropes 16.

Drive machine 18 includes motor 22 and drive sheave 24. Elevator system 10 employs a

2:1 roping arrangement in which the ends of ropes 16 terminate toward the top of hoistway

20 after looping under idler sheaves 12a and 14a on car 12 and counterweight 14 respectively. Ropes 16 wrap around drive sheave 24 between idler sheaves 12a on car 12 and idler sheave 14a on counterweight 14. Motor 22 of drive machine 18 is powered to turn drive sheave 24, which engages ropes 16 to move car 12 (and thereby counterweight 14) up and down hoistway 20. Counterweight 14 is configured to counterbalance the weight of car

12, which in turn reduces the torque required by drive machine 18 to raise and lower car 12. Additionally, counterweight 14 contributes to maintaining the tension in ropes 16 necessary to allow drive sheave 24 to drive car 12 without slipping.

Elevator traction members, e.g. ropes 16, may develop defects during elevator operation. For example, normal service wear, impact loading, fatigue, and corrosion may generate cracks, tears, or plastic deformation in one or more portions of the traction members. Embodiments of the present invention therefore provide methods and devices for inspecting in service elevator traction members to detect defects therein using eddy current sensors. Devices and methods according to the present invention may be used in relatively high speed elevator applications, e.g. up to 2.5 m/s (approximately 8.2 ft/s), and may detect surface and internal defects in traction members without contacting the traction members, without using permanent magnets, and without passing current throughout the traction members.

FIGS. 2 A and 2B are orthogonal views of an embodiment of an inspection device 30 according to the present invention. The inspection device 30 engages rope 16 and includes bracket 32, eddy current sensor 34, controller 36, rope guides 38, and handles 40. In FIGS. 2A and 2B, bracket 32 is a channel or U-shaped member to which eddy current sensor 34, rope guides 38, and handles 40 are connected. Sensor 34 is arranged adjacent to one side 16a of rope 16 such that when rope 16 is in motion, such as during operation of elevator system 10 of FIG. 1, successive portions of rope 16 pass by sensor 34. Controller 36 is communicatively connected to device 30 and configured to calibrate sensor 34 and interpret signals received from sensor 34 as rope 16 moves by sensor 34. Rope guides 38 are configured to position rope 16 as it moves by sensor 34.

An eddy current sensor, generally speaking, is a coil of wire through which alternating current is passed. Passing alternating current through the coil generates a magnetic field in and around the coil. The magnetic field in and around the sensor coil will change with the magnitude of the alternating current flowing through the coil. If the sensor is brought in close proximity to a conductive material, such as steel, the sensor's changing magnetic field induces current flow in the material. The induced current, i.e. eddy current, flows in closed loops in planes perpendicular to the magnetic flux produced by the sensor coil. The eddy currents produce their own magnetic fields that interact with the primary magnetic field of the sensor coil. By measuring changes in the resistance and inductive reactance of the sensor coil, information can be gathered about the test material. For example, the amount of material cutting through the sensor coil's magnetic field (e.g. the cross-sectional area of a steel rope), and the condition of the material (e.g. whether it contains cracks or other defects) may be measured by the eddy current sensor.

In FIGS. 2A and 2B, alternating current may be passed through a coil in eddy current sensor 34 as electrically conductive elevator rope 16 moves by sensor 34. The alternating current passing through sensor 34 generates a magnetic field in and around sensor 34, which magnetic field in turn induces eddy currents in rope 16. The induced eddy currents in rope 16 generate magnetic fields that interact with the primary magnetic fields in sensor 34. Sensor 34 may then generate signals by measuring changes in, for example, the resistance and inductive reactance in sensor 34 caused by the interaction between the eddy current magnetic field in rope 16 and the magnetic field in and around sensor 34. The signals generated by sensor 34 may then be sent to controller 36.

In practice, inspection device 30 may be employed manually by an operator or automatically by fixing device 30 adjacent rope 16 in elevator hoistway 20 and configuring device 30 to communicate information to a local or remote location. In manual operation, an operator may use inspection device 30 by entering hoistway 20 and positioning device 30 adjacent rope 16 using handles 40. In particular, the operator may position bracket 32 so that rope 16 passes through the channel of bracket 32 and thereby moves by sensor 34. As elevator rope 16 moves by sensor 34, eddy current sensors 34 generate signals that may be sent to controller 36.

As discussed above, controller 36 is configured to calibrate sensor 34 and interpret signals received from sensor 34 as rope 16 moves by sensor 34. In the schematic view of inspection device 30 of FIG. 3, controller 36 includes rope speed dial 36a, adjustable filters 36b, and severity level indicator 36c. Controller 36 may calibrate sensor 34 based on, for example, the speed and diameter of rope 16. For example, controller 36 includes rope speed dial 36a to calibrate sensor 34 to the particular speed of the rope being inspected. Controller 36 also includes adjustable filters 36b, e.g. low and high pass filters, configured to filter ambient noise present in the elevator hoistway from sensor 34. Controller 36 may also be configured to adjust the phase and sensitivity of sensor 34. In addition to calibrating signals received from sensor 34, controller 36 may also interpret the signals received from sensor 34 to detect defects in rope 16. Controller 36 may include severity level indicator 36c to provide a visual indication of defects detected in rope 16 by interpreting the signals received from sensor 34. As shown in FIG. 3, severity level indicator 36c may be a visual display with one or more colors and sectors by which the occurrence and severity of defects detected in rope 16 are indicated by controller 36.

In an additional embodiment, controller 36 may be connected to an external device to communicate defects detected in rope 16 by interpreting the signals from sensor 34. In the schematic view of inspection device 30 of FIG. 4, device 30 includes controller 36 communicatively (e.g., a wired connection, a wireless connection, a corporate LAN or WAN connection, an internet connection, a modem connection, etc.) connected to monitor 42. Controller 36 may interpret signals received from eddy current sensor 34 to determine the presence and severity of defects in rope 16. Controller 36 may then transmit the signals to monitor 42 to display the interpreted signals on, for example, a graph. In addition to monitor 36, controller 36 may be connected to other devices, such as printers, computers, or equivalent devices configured to output data representative of defects detected in rope 16.

FIG. 5A is a schematic of inspection device 30 employed in an automatic mode in elevator system 10. In FIG. 5, inspection device 30 is fixed in elevator hoistway 20 adjacent rope 16. Inspection device 30 may be fixed in any way appropriate for supporting device 30 and arranging device 30 such that rope 16 moves by sensor 34. For example, device 30 may connected to a stanchion positioned in the machine room of system 10 toward the top of hoistway 20. In order to inspect as much of rope 16 as possible, it will be advantageous to position device 30 in relatively close proximity to drive sheave 24 as shown in FIG. 5A. In the automatic operation mode, inspection device 30 may be configured to communicate defects detected in rope 16 to a local or remote location away from hoistway 20 in which device 30 is fixed. For example, as illustrated in FIG. 5B, inspection device 30 may detect defects by controller 36 interpreting signals from sensor 34. Controller 36 may be configured to then send the rope degradation information over network 44 to, for example, a remote call center or a local or remote field engineer 46. A Remote Elevator Monitoring (REM) system may be connected to network 44 and may be configured to receive and route control information, such as the rope degradation information sent by controller 36 from the elevator system 10, to call center/field engineer 46. After controller 36 transmits the rope degradation information to call center/field engineer 46, the receiving device or personnel may automatically or manually remotely shut down operation of elevator system 10 based on the presence and severity of defects in rope 16 as represented by the rope degradation information. Network 44 may include one or more public or private network infrastructures, such as a corporate LAN or WAN, the public telephone network (POTS), the Internet, and/or other communication protocol(s). The information sent over network 44 may be transmitted via wired, such as Ethernet, ISDN, or Tl, or wireless, such as Wi-Fi or satellite, transport mediums.

Eddy currents concentrate near the surface adjacent to the sensor coil and their strength decreases exponentially with distance from the coil. This phenomenon is known as the skin effect. The skin effect arises because eddy currents near the surface essentially shield the coil's magnetic field, thereby weakening the magnetic field at greater depths and reducing induced eddy currents. Because the skin effect may preclude inspecting the entire cross-section of rope 16 in some applications, an elevator system may include two inspection devices 30 in series as shown in the schematic view of elevator system 10 in FIG. 6. In FIG. 6, elevator system 10 includes two inspection devices 30 fixed in elevator hoistway 20 adjacent rope 16. Inspection devices 30 are arranged in series adjacent opposite sides 16a, 16b of rope 16. Devices 30 are therefore arranged such that one eddy current sensor 34 is adjacent to one side 16a of rope 16 and a second sensor 34 is arranged adjacent to an opposite side 16b of rope 16. Employing two inspection devices 30 and thereby two eddy current sensors 34 effectively cuts in half the cross-sectional area of rope 16 that would otherwise need to be inspected by a single sensor 34. In this way, embodiments according to the present invention are capable of inspecting substantially all of the cross-section of rope 16 to detect surface, as well as internal defects in rope 16. Although the above discussion is made with reference to inspecting a single traction member, additional embodiments may inspect multiple traction members simultaneously. For example, multiple traction member inspection devices could be employed in parallel to inspect multiple traction members as shown in FIG. 7. Additionally, a single device may be configured with multiple eddy current sensors respectively arranged adjacent multiple traction members. The eddy current sensors could be connected to a single controller or each sensor may be connected to a distinct controller. Finally, multiple serial pairs of inspection devices such as the pair shown in FIG. 6 may be employed in parallel to inspect multiple traction members.

In addition to traction member inspection devices and elevator systems including such devices, embodiments of the present invention include methods of detecting defects in a moving elevator traction member, which methods include sensing physical variations in the moving traction member with an eddy current sensor to detect defects in the traction member, and transmitting the defects detected in the moving traction member to an output device. Sensing physical variations in the traction member may include, for example, applying an alternating electrical current to a metallic coil in the eddy current sensor, arranging the metallic coil adjacent the moving traction member, measuring electrical current induced in the moving traction member by magnetic fields generated in and around the metallic coil, and interpreting the measured induced current to detect defects in the moving traction member. The output device to which the detected defects are transmitted may be one of, for example, a defect severity level indicator, a printer, a monitor, or a computer.

Embodiments of the present invention provide several advantages over prior traction member inspection systems. Embodiments of the present invention provide methods and devices for inspecting in-service elevator traction members to detect defects using eddy current sensors. Devices and methods according to the present invention may be used in relatively high speed elevator applications, e.g. up to 2.5 m/s (approximately 8.2 ft/s), and may detect surface and internal defects in traction members without contacting the traction members, without using permanent magnets, and without passing current throughout the traction members. Depending on the application, a single inspection device or a pair of inspection devices in series may be employed to inspect a traction member. Additionally, pairs of serial inspection devices may be employed in parallel to inspect several traction members simultaneously. Finally, embodiments of the present invention may be employed manually by an operator or automatically by fixing an inspection device adjacent a traction member in the elevator hoistway and configuring the device to communicate information to a local or remote location. Methods and devices according to the present invention therefore provide cost effective inspection techniques adaptable to a wide variety of elevator system applications to reduce system material and maintenance costs and increase safety.

The aforementioned discussion is intended to be merely illustrative of the present invention and should not be construed as limiting the appended claims to any particular embodiment or group of embodiments. Thus, while the present invention has been described in particular detail with reference to specific exemplary embodiments thereof, it should also be appreciated that numerous modifications and changes may be made thereto without departing from the broader and intended scope of the invention as set forth in the claims that follow.

The specification and drawings are accordingly to be regarded in an illustrative manner and are not intended to limit the scope of the appended claims. In light of the foregoing disclosure of the present invention, one versed in the art would appreciate that there may be other embodiments and modifications within the scope of the present invention. Accordingly, all modifications attainable by one versed in the art from the present disclosure within the scope of the present invention are to be included as further embodiments of the present invention. The scope of the present invention is to be defined as set forth in the following claims.

Claims

CLAIMS:

1. A device for detecting defects in a moving elevator traction member comprising: an eddy current sensor configured to be arranged adjacent the moving traction member; and a controller configured to calibrate the sensor and interpret signals received from the sensor as the traction member moves by the sensor.

2. The device of claim 1 further comprising a bracket to which the sensor is connected.

3. The device of claim 2 further comprising a guide connected to the bracket and configured to position the traction member as the traction member moves by the sensor.

4. The device of claim 2 further comprising a handle connected to the bracket and configured to allow an operator to manually inspect the moving traction member for defects.

5. The device of claim 1, wherein the controller is configured to calibrate the sensor based on one or both of a speed and a size of the moving traction member.

6. The device of claim 1, wherein the controller is connected to an external device to communicate defects detected by interpreting the signals received from the sensor.

7. The device of claim 6, wherein the external device is selected from a group of devices comprising printers, monitors, and computers.

8. The device of claim 1, wherein the controller communicates defects detected by interpreting the signals received from the sensor to one or more of a remote call center, a field engineer, and Remote Elevator Monitoring system.

9. The device of claim 1, wherein the controller comprises a visual display configured to indicate the occurrence and severity of defects detected by interpreting the signals received from the sensor.

10. An elevator system comprising: a traction member; and a first inspection device configured to detect defects in the traction member, the first inspection device comprising: an eddy current sensor configured to be arranged adjacent the traction member; and a controller configured to calibrate the sensor and interpret signals received from the sensor as the traction member moves by the sensor.

11. The system of claim 10, wherein the first inspection device further comprises a bracket to which the sensor is connected.

12. The system of claim 11 further comprising a guide connected to the bracket and configured to position the traction member as the traction member moves by the sensor.

13. The system of claim 11 further comprising a handle connected to the bracket and configured to allow an operator to manually inspect the moving traction member for defects.

14. The system of claim 10, wherein the controller is configured to calibrate the sensor based on one or both of a speed and a material of the moving traction member.

15. The system of claim 10, wherein the controller is connected to an external device to communicate defects detected by interpreting the signals received from the sensor.

16. The system of claim 15, wherein the external device is selected from a group of devices comprising printers, monitors, and computers.

17. The system of claim 10, wherein the controller communicates defects detected by interpreting the signals received from the sensor to one or more of a remote call center, a field engineer, and Remote Elevator Monitoring system.

18. The system of claim 10, wherein the controller comprises a visual display configured to indicate the occurrence and severity of defects detected by interpreting the signals received from the sensor.

19. The system of claim 10 further comprising: a drive machine configured to receive and drive the traction member inside a hoistway, wherein the inspection device is arranged proximate to the drive machine.

20. The system of claim 19, wherein the drive machine and the inspection device are arranged in a machine toward a top of the hoistway.

21. The system of claim 10 further comprising: a second inspection device configured to detect defects in the traction member and arranged in series with the first inspection device.

22. The system of claim 21, wherein the first and the second inspection devices are respectively arranged adjacent first and second opposite sides of the traction member.

23. The system of claim 10 further comprising: a second traction member; and a second inspection device configured to detect defects in the second traction member, the second inspection device comprising a second eddy current sensor configured to be arranged adjacent the second traction member.

24. The system of claim 23, wherein the controller is configured to calibrate the second sensor and interpret signals received from the second sensor as the second traction member moves by the second sensor.

25. A method of detecting defects in a moving elevator traction member of an elevator, the method comprising: sensing physical variations in the moving traction member with an eddy current sensor to detect defects in the traction member; and transmitting the defects detected in the moving traction member to an external device.

26. The method of claim 25, wherein sensing physical variations in the traction member comprises: applying an alternating electrical current to a metallic coil in the eddy current sensor; arranging the metallic coil adjacent the moving traction member; measuring electrical current induced in the moving traction member by magnetic fields generated in and around the metallic coil; and interpreting the measured induced current to detect defects in the moving traction member.

27. The method of claim 25, wherein the external device is one of a defect severity level indicator, a printer, a monitor, or a computer.

28. The method of claim 25, wherein the external device is associated with one of a call center, a field engineer, and a Remote Elevator Monitoring system.

29. The method of claim 25 further comprising ceasing operation of the elevator based on one or more of a number and severity of the defects detected in the moving traction member.