WO2009075661A1

WO2009075661A1 - Methods and apparatuses for detecting degradation of a non-metallic, elastically deformable buffer

Info

Publication number: WO2009075661A1
Application number: PCT/US2007/025251
Authority: WO
Inventors: David Wayne Mckee; Mark S. Thompson; Brad Guilani; Nigel Morris; Anthony Cooney
Original assignee: Otis Elevator Company
Priority date: 2007-12-11
Filing date: 2007-12-11
Publication date: 2009-06-18

Abstract

An elevator safety apparatus includes a deformable member (18) configured to buffer a mass (14, 26) in a hoistway (12) of an elevator system (10) and one or more sensors (20) configured to sense degradation of the deformable member (18).

Description

METHODS AND APPARATUSES FOR DETECTING DEGRADATION OF A NON- METALLIC, ELASTICALLY DEFORMABLE BUFFER

BACKGROUND The present invention relates to elevator safety systems. In particular, the present invention relates to methods and apparatuses for detecting degradation of a deformable buffer used to buffer a mass in an elevator system.

Safety buffers are required on elevator systems. Safety buffers are commonly arranged in the bottom of a hoistway, sometimes referred to as the "pit," and are configured to decelerate and stop masses (for example elevator cars or counterweights) in the system, during an overrun condition of either of the masses due to a system malfunction. Deformable safety buffers, such as, for example, polyurethane foam buffers, are acceptable in several countries for use in some elevator system configurations, for example, systems having elevator car speeds at or below 1.0 meters/second. The use of deformable buffers provides significant space and cost savings over other buffer arrangements. Prior deformable buffer arrangements and elevator systems including such buffers lack an objective method and apparatus for detecting degradation of the deformable buffer. Prior deformable buffer inspection methods include visual inspection of the buffer to identify patent defects. Prior methods are subjective and labor intensive and require access to the pit. Additionally, prior deformable buffer arrangements do not include an apparatus configured to positively sense degradation of the deformable buffer without the need for direct visual inspection.

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

SUMMARY

Embodiments of the present invention include an elevator safety apparatus comprising a deformable member configured to buffer a mass in a hoistway of an elevator system and one or more sensors configured to sense degradation of the deformable member. Embodiments of the present invention also include a method of inspecting a deformable member configured to buffer a mass in an elevator system, which method includes providing the deformable member, which includes at least one degradation sensor, in a hoistway of the elevator system and sensing degradation of the deformable member. 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 an elevator system including an embodiment of a deformable buffer according to the present invention.

FIGS. 2A and 2B are detail section views of a deformable buffer degradation sensor used in conjunction with the buffer shown in FIG. 1.

FIGS. 3A and 3B are detail views of an elevator system with the deformable buffer of FIG. 1 compressed by an elevator car.

FIGS. 4A and 4B are detail views of an elevator system including an alternative embodiment of a deformable buffer deflected by an elevator car.

FIG. 5 is a detail view of the elevator system of FIGS. 4A and 4B including an alternative sensor arranged adjacent the deformable buffer in the elevator hoistway.

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 an elevator system 10 including a hoistway 12, a car 14, drive members 16, deformable members 18 (also called a "buffer"), a sensor

20, a control system 22, a hoist machine 24, and a counterweight 26. The car 14 may be configured to move up and down the hoistway 12 via the drive members 16. The drive members 16 may be, for example, cables as shown in FIG. 1, or alternatively belts, that are connected by way of the hoist machine 24 to a counterweight 26. The deformable members 18, which may in some embodiments be formed of polyurethane foam, may be arranged toward the bottom of the hoistway 12, for example, in the pit of the hoistway 12. The sensor 20, which in some embodiments of the present invention may include one or more sensors per deformable member 18, is attached to the deformable member 18. The sensor 20 may be attached to a surface of the deformable members 18, or alternatively may be embedded into the deformable members 18. As shown in FIG. 1, the deformable member 18 may be generally tubular or cylindrical in shape (of course, other shapes that have, e.g., rectangular cross-sections may also be employed) and the sensor 20 may be embedded into the deformable member 18. In embodiments where the sensor 20 includes one or more sensors attached to the deformable member 18, the one or more sensors 20 may be, for example, attached to both interior and exterior surfaces of the deformable member 18.

The deformable members 18 are configured to buffer the car 14 and the counterweight 26 in the hoistway 12. For example, in the event of a malfunction of the drive members 16 or the machine to which the drive members 16 are attached, the car 14 may be subjected to an uncontrolled overrun in the hoistway 12. The deformable member 18 may be arranged toward the bottom of the hoistway 12 to buffer the uncontrolled overrun of the car 14, and/or the counterweight 26, and thereby substantially reduce the force of impact of the car 14 or counterweight 26 in the pit of the hoistway 12. Embodiments of the present invention also include elevator systems with multiple deformable members that correspondingly buffer more than one mass, as shown in FIG. 1, or multiple deformable members that buffer a single mass. For example, three buffers may be provided, two of which buffer the car 14 and the other of which buffers the counterweight 26.

To monitor the ability of the deformable member 18 to buffer the impact of the car 14, the sensor 20 attached to the deformable member 18 is configured to sense degradation of the deformable member 18. The sensor 20 may be configured to sense degradation of the deformable member 18 by sensing, for example, an inherent strength of the deformable member 18, without a mass load applied thereon. The sensor 20 may be configured to apply a test force to a portion of the deformable member 18 during normal operation of elevator system 10 where the car 14 does not load the deformable member 18. The sensor 20 may be mechanically actuated when the deformable member 18 fails to withstand the applied test force, thereby indicating degradation of the deformable member 18.

For example, FIGS. 2A and 2B are detail section views of the sensor 20, which includes a plunger 20a, a cylinder 20b, a spring 20c, and a first switch lead 2Od. The sensor 20 is embedded in the deformable member 18 by, for example, molding the sensor 20 into the deformable member 18. In FIG. 2A, the plunger 20a includes a body 2Oe, barbs 2Of, and a second switch lead 2Og. Both of the switch leads 2Od, 2Og are connected (wired or wirelessly) to a controller 22.

The body 2Oe of the plunger 20a may be displaced through cylinder 20b and sunken into the deformable member 18. The barbs 2Of catch on a portion the deformable member 18 between the barbs 2Of and the end of the cylinder 20b. The strength of the deformable member 18 may act to resist the force created by the spring 20c, which is placed under compression by the displacement of the plunger 20a when the sensor 20 is molded to the buffer 18. The strength of a structurally sound deformable member 18 will act to hold the plunger 20a in place, as shown in FIG. 2A, against the compressive force of the spring 20c. Once the strength of the deformable member 18 degrades beyond a particular value, the force created by compression of the spring 20c overcomes the strength of deformable member 18. The deformable member 18 releases the barbs 2Of of the plunger 20a, which acts under the force of the spring 20c to bring the second switch lead 2Og into contact with the first switch lead 2Od, thereby closing an electric circuit with the controller 22. When the electric circuit is closed, an error or alarm protocol may be implemented. For example, the controller 22 could be programmed, upon closing of the electric circuit, to activate a siren or to produce a warning light. Similarly, in embodiments in which the controller 22 is connected to a network, the controller 22 could send an electronic message to, for example, a building owner or a service provider, which message would indicate that the deformable buffer member 18 should be replaced. As shown in FIGS. 2A and 2B, the sensor 20 may be configured to signal degradation of the deformable member 18 by tying the mechanical actuation of plunger 20a to an electrical switch. As the sensor 20 is connected to the control system 22, the sensor 20 may be configured to communicate data related to the degradation of the deformable member 18 to the control system 22, thereby substantially removing the need to directly inspect signals from the sensor 20 in, for example, the pit of the hoistway 12. The elevator control system 22 may be located, for example, in the hoistway 12 or the machine room of the elevator system 10. In another embodiment of the present invention, the control system 22 may be located remotely from the site of the elevator system 10. FIGS. 3 A and 3B are detail views of the elevator system 10 including an alternative sensor 28 configured to sense degradation of the deformable member 18 by sensing compression of the deformable member 18 under the load of the car 14. The sensor 28 includes a connector 28a, a displacement rod 28b, and a switch 28c. The connector 28a is connected to the deformable member 18. The displacement rod 28b is connected to the connector 28a and movably connected to the switch 28c. The switch 28c is connected to the deformable member 18 and may be, for example, a magnetic switch. In FIG. 3 A, the deformable member 18 is compressed by the static load of the car 14. The sensor 28 senses a first compression of the deformable member 18, as compression of the deformable member 18 causes connector 28a to displace rod 28b which displacement may act to create an electrical signal from magnetic switch 28c. The compression of the deformable member 18 in FIG. 3 A may, for example, correspond to a compression range that indicates the deformable member 18 is in condition for continued use as a buffer for the car 14 in the elevator system 10. In FIG. 3B, the car 14 is statically loaded on top of the deformable member 18 and the sensor 28 senses a second compression of the deformable member 18, which may, for example, correspond to a compression range that indicates the deformable member 18 is no longer in condition for use as a buffer of the car 14 in the elevator system 10. In both FIGS. 3A and 3B, the sensor 28 may be configured to communicate with the elevator control system 22, thereby substantially removing the need for direct inspection of the sensor 28 or the deformable member 18 in the hoistway 12.

The sensor 28 used in embodiments of the present invention to sense compression of the deformable member 18 may include known linear displacement sensors, such as linear variable differential transformers and linear variable inductive transducers. In an alternative embodiment of the present invention, a sensor configured to sense degradation of the deformable member 18 by sensing compression of the deformable member 18 under the load of the car 14 may also include coating the deformable member 18 with an inherently conducting polymer, such as polypyrrole (PPy), which coated deformable member 18 may exhibit a measurable linear relationship between conductance and applied stress. A sensor, or sensors, may also sense compression of the deformable member 18 indirectly by, for example, measuring the position of the car 14 in the hoistway 12. For example, elevator systems are commonly equipped with an elevator car position reference system, which senses and communicates the position of the car in the hoistway. The car position system may be used to sense compression of the deformable member 18 under the load of the car 14 by measuring the position of the car 14 in the hoistway away from a reference position, for example, the top of the deformable member 18 without a mass load applied. FIGS. 4 A and 4B are detail views of the elevator system 10 including an alternative sensor 30 configured to sense deflection of the deformable member 18. The deformable member 18 may comprise, for example, a substantially incompressible material such as polyurethane and therefore may only deflect, as opposed to compress, under a load applied by the car 14. In some embodiments of the present invention, the sensor 30 may be configured to sense degradation of the deformable member 18 by sensing deflection of the deformable member 18 under the load of the car 14 as illustrated in FIGS. 4A and 4B. In FIG. 4A, the car 14 is statically loaded on top of the deformable member 18 and the sensor 30 senses a first deflection of the deformable member 18, which may, for example, correspond to a deflection range that indicates the deformable member 18 is in condition for continued use as a buffer for the car 14 in the elevator system 10. In FIG. 4B, the car 14 is statically loaded on top of the deformable member 18 and the sensor 30 senses a second deflection of the deformable member 18, which may, for example, correspond to a deflection range that indicates the deformable member 18 is no longer in condition for use as a buffer of the car 14 in the elevator system 10. In both FIGS. 4A and 4B, the sensor 30 may be configured to communicate with the elevator control system 22, thereby substantially removing the need for direct inspection of the sensor 30 or the deformable member 18 in the hoistway 12. Sensor 30 may be, for example, a ring shaped member arranged around the perimeter of the deformable member 18 as illustrated in FIGS. 4 A and 4B. The ring shaped sensor 30 may be configured to deform upon deflection of the deformable member 18, which deformation of the sensor 30 may be correlated to the deflection of the deformable member 18. The sensor 30 may include, for example, a strain gage. In other embodiments the sensor may be in the form of a stretchable, conductive tape that will rupture when stretched beyond a predetermined threshold; when the tape ruptures, an electric circuit may be opened, thereby signaling to the controller that the deformable member 18 should be replaced.

FIG. 5 is a detail view of elevator system 10 including an alternative sensor 32 arranged in the hoistway 12 adjacent the deformable member 18. The sensor 32 may be, for example, an optical array sensor 32 including an emitter 32a, which emits a light curtain 32b to be received by a collector 32c. The sensor 32 may be arranged such that a particular amount of growth in the perimeter of the deformable member 18 causes the light curtain 32b to be interrupted by the deformable member 18. The interruption of the light curtain 32b may cause the collector 32c to signal the deflection in the deformable member 18 to, for example, the elevator control system 22. In another embodiment of the present invention, the sensor 32 may include mechanical indicators, such as pins or fingers, instead of an optical curtain. The mechanical indicators may be arranged adjacent the deformable member 18 and configured to be displaced by the deformable member 18 as the deformable member 18 deflects under the load of the car 14. Displacement of the mechanical indicators may then be correlated to the amount the deformable member 18 deflects or the mechanical indicators may activate a switch to signal the amount of deflection of the deformable member 18 to, for example, the control system 22.

Embodiments of the present invention have been described with reference to four different general types of sensors, the embodiments of FIGS. 1-2B, FIGS. 3A-3B, FIGS. 4A-4B, and FIG. 5 respectively, used separately to sense degradation of the deformable member. However, the present invention also includes embodiments employing different types of sensors in combination to sense degradation of the deformable member. For example, the present invention includes embodiments having a deformable member with sensors configured to sense compression of the deformable member and sensors configured to sense deflection of the deformable member. Additionally, the present invention includes embodiments having sensors attached to or embedded in the deformable member and sensors merely adjacent the deformable member in the elevator hoistway.

Embodiments of the present invention also include a method of inspecting a deformable member configured to buffer a mass in an elevator system, which method includes positioning the deformable member, which includes at least one degradation sensor, toward an end of a hoistway of the elevator system and sensing degradation of the deformable member. The deformable member may be positioned, for example, toward the bottom of the hoistway in the "pit," toward the top of the hoistway, or mounted on the car or the counterweight. Sensing degradation of the deformable member may include, for example, sensing compression and deflection of the deformable member statically loaded with the mass. Additionally, sensing degradation of the deformable member may include sensing an inherent strength of the deformable member without a mass load applied to the deformable member. In addition to positioning the deformable member and sensing degradation of the deformable member, the inspection method may also include communicating with an elevator control system, for example over wired or wireless connections, upon sensing degradation of the deformable member. Methods and apparatuses according to the present invention have several advantages over prior systems including deformable buffers and methods of inspecting such buffers. Embodiments of the present invention provide a positive and simple way to detect degradation of deformable buffers used in elevator systems without the need for direct inspection of the buffer. Additionally, the present invention includes methods for inspecting deformable buffers positioned in an elevator hoistway by sensing degradation of the buffer. Positively detecting the degradation of deformable buffers and configuring embodiments of the present invention to communicate with an on or off-site elevator control system increases the reliability of the buffers and decreases maintenance costs and safety risks by removing the need for direct inspection of the buffers in the hoistway pit.

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. For example, although electrical, mechanical, and optical sensors have been described the sensors could be electro-mechanical, pneumatic, hydraulic, magnetic, electromagnetic, etc. 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. An elevator safety apparatus comprising: a deformable member configured to buffer a mass in a hoistway of an elevator system; and one or more sensors configured to sense degradation of the deformable member.

2. The apparatus of claim 1 , wherein one or more of the one or more sensors are configured to sense degradation of the deformable member by sensing a compressive force in the deformable member when statically loaded by the mass.

3. The apparatus of claim 1, wherein one or more of the one or more sensors are configured to sense degradation of the deformable member by sensing lateral deflection of the deformable member when statically loaded by the mass.

4. The apparatus of claim 1, wherein one or more of the one or more sensors are configured to sense degradation of the deformable member by sensing vertical deflection of the deformable member when statically loaded by the mass.

5. The apparatus of claim 1, wherein one or more of the one or more sensors are configured to sense degradation of the deformable member by sensing an inherent strength of the deformable member without a mass load applied to the at least one deformable member.

6. The apparatus of claim 5, wherein the one or more sensors are configured to apply one or more forces to one or more portions of the deformable member and to be mechanically actuated when the deformable member fails to withstand one or more of the one or more applied forces.

7. The apparatus of claim 1, wherein the one or more sensors are selected from a group of sensors comprising electrical, mechanical, electro-mechanical, magnetic, electromagnetic, pneumatic, hydraulic and optical sensors.

8. The apparatus of claim 1, wherein one or more of the one or more sensors are attached to one or more surfaces of the deformable member.

9. The apparatus of claim 1, wherein one or more of the one or more sensors are embedded in the deformable member.

10. The apparatus of claim 1, wherein the apparatus is configured to be mounted in a pit of the hoistway of the elevator system.

11. The apparatus of claim 1, wherein the apparatus is configured to be mounted toward a top of the hoistway of the elevator system.

12. The apparatus of claim 1, wherein the apparatus is configured to be mounted on a car in the hoistway of the elevator system.

13. The apparatus of claim 1 , wherein the apparatus is configured to be mounted on a counterweight in the hoistway of the elevator system.

14. The apparatus of claim 1, wherein one or more of the one or more sensors are configured to communicate with an elevator control system upon sensing degradation of the deformable member.

15. The apparatus of claim 14, wherein the one or more sensors are configured to communicate with the elevator control system over one or more wired connections between the one or more sensors and the elevator control system.

16. The apparatus of claim 14, wherein the one or more sensors are configured to communicate with the elevator control system over one or more wireless connections between the one or more sensors and the elevator control system.

17. The apparatus of claim 1, wherein the one or more sensors comprise: an elevator car position reference system configured to sense the position of an elevator car in the hoistway, wherein the elevator car position reference system senses degradation of the deformable member by sensing the position of the elevator car when the elevator car is statically loaded on the deformable member.

18. An elevator system comprising: a mass configured to move up and down in a hoistway; at least one deformable member configured to buffer the mass; and one or more sensors configured to sense degradation of the at least one deformable member.

19. The system of claim 18, wherein one or more of the one or more sensors are configured to sense degradation of the at least one deformable member by sensing a compressive force in at least one of the at least one deformable member when statically loaded by the mass.

20. The system of claim 18, wherein one or more of the one or more sensors are configured to sense degradation of the at least one deformable member by sensing lateral deflection of the at least one deformable member when statically loaded by the mass.

21. The system of claim 18, wherein one or more of the one or more sensors are configured to sense degradation of the at least one deformable member by sensing vertical deflection of the at least one deformable member when statically loaded by the mass.

22. The system of claim 18, wherein one or more of the one or more sensors are configured to sense degradation of the deformable member by sensing an inherent strength of the at least one deformable member without a mass load applied to the at least one deformable member.

23. The system of claim 22, wherein the one or more sensors are configured to apply one or more forces to one or more portions of the at least one deformable member and to be mechanically actuated when the at least one deformable member fails to withstand one or more of the one or more applied forces.

24. The system of claim 18, wherein the one or more sensors are selected from a group of sensors comprising electrical, mechanical, electro-mechanical, magnetic, electromagnetic, pneumatic, hydraulic and optical sensors.

25. The system of claim 18, wherein one or more of the one or more sensors are attached to one or more surfaces of the at least one deformable member.

26. The system of claim 18, wherein one or more of the one or more sensors are embedded in the at least one deformable member.

27. The system of claim 18, wherein one or more of the one or more sensors are configured to be mounted in the deformable member in a pit of the hoistway of the elevator system.

28. The system of claim 18, wherein one or more of the one or more sensors are configured to be mounted in the deformable member toward a top of the hoistway of the elevator system.

29. The system of claim 18, wherein one or more of the one or more sensors are configured to be mounted in the deformable member mounted on a car in the hoistway of the elevator system.

30. The system of claim 18, wherein one or more of the one or more sensors are configured to be mounted in the deformable member mounted on a counterweight in the hoistway of the elevator system.

31. The system of claim 18, wherein one or more of the one or more sensors are configured to communicate with an elevator control system upon sensing degradation of the at least one deformable member.

32. The system of claim 31, wherein the one or more sensors are configured to communicate with the elevator control system over one or more wired connections between the one or more sensors and the elevator control system.

33. The system of claim 31, wherein the one or more sensors are configured to communicate with the elevator control system over one or more wireless connections between the one or more sensors and the elevator control system.

34. The system of claim 18, wherein the mass comprises an elevator car.

35. The system of claim 18, wherein the mass comprises a counterweight.

36. A method of inspecting a deformable member configured to buffer a mass in an elevator system, the method comprising: positioning the deformable member, which includes at least one degradation sensor, toward an end of a hoistway of the elevator system; and sensing degradation of the deformable member.

37. The method of claim 36, wherein sensing degradation of the deformable member comprises sensing compression of the deformable member when statically loaded by the mass.

38. The method of claim 36, wherein sensing degradation of the deformable member comprises sensing lateral deflection of the deformable member when statically loaded by the mass.

39. The method of claim 36, wherein sensing degradation of the deformable member comprises sensing vertical deflection of the deformable member when statically loaded by the mass.

40. The method of claim 36, wherein sensing degradation of the deformable member comprises sensing an inherent strength of the deformable member without a mass load applied to the deformable member.

41. The method of claim 36, wherein sensing degradation of the deformable member comprises: sensing compression of the deformable member statically loaded by the mass; sensing deflection of the deformable member statically loaded by the mass; and sensing an inherent strength of the deformable member without a mass load applied to the deformable member.

42. The method of claim 36, further comprising: communicating with an elevator control system upon sensing degradation of the deformable member.

43. The method of claim 36, wherein sensing degradation of the deformable member comprises sensing the position of an elevator car when the elevator car is statically loaded on the deformable member.