WO2009110907A1

WO2009110907A1 - Secondary elevator car leveler

Info

Publication number: WO2009110907A1
Application number: PCT/US2008/056163
Authority: WO
Inventors: Randall Keith Roberts; Daniel Rush
Original assignee: Otis Elevator Company
Priority date: 2008-03-07
Filing date: 2008-03-07
Publication date: 2009-09-11

Abstract

An exemplary device for use in an elevator system (20) includes a leveler (40) that is configured to move into and selectively maintain a vertical position in an elevator hoistway. A controller (48) is configured to determine a desired vertical position of the leveler (40) based upon a corresponding intended position of an elevator car (22). The controller (48) is configured to adjust a vertical position of the leveler (40) responsive to a difference between an actual vertical position of the leveler and the desired vertical position.

Description

SECONDARY ELEVATOR CAR LEVELER

BACKGROUND

[0001] Elevator systems include an elevator car that moves between various landings to provide elevator service to different levels within a building, for example. A machine includes a motor and brake for selectively moving the elevator car to a desired position and then maintaining the car in that position. A machine controller controls operation of the machine to respond to passenger requests for elevator service and to maintain the elevator car at a selected landing in a known manner. [0002] One challenge associated with elevator systems is maintaining the car at an appropriate height relative to a landing to facilitate easy passage between the elevator car and a lobby where the elevator car is parked. The car floor is ideally kept level with the landing floor to make it easy for passengers to move between the lobby and the elevator car while minimizing the possibility of someone tripping. Current elevator codes define a displacement threshold that establishes a maximum difference that is allowable between the landing floor and the elevator car floor. When that distance is above the code threshold, the elevator system must re-level or correct the position of the elevator car.

[0003] The conventional elevator re-leveling approach includes sensing the amount of car-to-floor displacement. This is typically accomplished using an encoder on the primary position transducer or governor associated with the elevator car. When the displacement exceeds a set threshold, a re-leveling process begins. The machine controller makes a determination regarding the weight of the car and pre- torques the motor for lifting the car before releasing the machine brake. The motor current is then controlled using an inner velocity servo loop that has an outer position loop using a fixed gain on the position error.

[0004] The conventional approach to re-leveling an elevator car works well in most situations. In high rise buildings and ultra high rise buildings, the conventional approach may not provide satisfactory results. This occurs, in part, because the effective stiffness of elevator roping members decreases proportionally with their length. Accordingly, a longer elevator roping arrangement allows for increased amounts of static deflection responsive to changing loads on the elevator car, which results from passengers entering or exiting the car, for example. Additionally, there is time delay between motor action, car reaction and position transducer response that increases linearly with the height of the hoistway. Such a delay introduces potential stability issues in the position feedback logic associated with the conventional approach. Another issue is that the reduced stiffness of the roping arrangement reduces the resonant frequency associated with elevator car bounce resulting from changes in the load on the car. The lower frequency resonance creates a limitation on traditional control logic gains, which limits bandwidth and, therefore, performance.

SUMMARY [0005] An exemplary device for use in an elevator system includes a leveler that is configured to move into and selectively maintain a vertical position in an elevator hoistway. A controller is configured to determine a desired vertical position of the leveler based upon a corresponding intended position of an elevator car. The controller is configured to adjust a vertical position of the leveler responsive to a difference between an actual vertical position of the leveler and the desired vertical position.

[0006] An exemplary method of controlling the position of an elevator car includes determining an intended position of the elevator car. The elevator car is moved to the intended position using a machine controller that is configured to control a position of the elevator car. A leveler that is at least selectively associated with the elevator car is moved into a desired vertical position corresponding to the intended position of the elevator car. The leveler provides support for maintaining the elevator car in the intended position. A vertical position of the leveler is selectively adjusted responsive to a difference between the desired vertical position and an actual position of the leveler.

[0007] The various features and advantages of the disclosed examples will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 schematically illustrates selected portions of an elevator system.

[0009] Figure 2 schematically illustrates an example leveler. [00010] Figure 3 schematically illustrates another example leveler configuration.

[00011] Figure 4 schematically illustrates another example leveler configuration. [oooi2] Figure 5 schematically illustrates another example leveler configuration.

DETAILED DESCRIPTION

[oooi3] Figure 1 schematically illustrates selected portions of an elevator system 20. An elevator car 22 is moveable within a hoistway along guide rails 24. An elevator machine 26 includes a motor and brake that controls movement of a roping arrangement 28 to control the movement and position of the elevator car 22. A machine controller 30 controls operation of the elevator machine 26 responsive to passenger requests for elevator service and other control parameters in a generally known manner.

[oooi4] The illustrated example includes a primary position transducer (PPT) 32 that provides position feedback information to the machine controller 30 regarding the position of the elevator car 22. In this example, the PPT 32 includes an encoder wheel and a rope or tape that operate in a known manner for providing position information to the machine controller 30.

[oooi5] A leveler 40 is at least selectively associated with the elevator car 22 to facilitate maintaining the elevator car at an intended position within the hoistway when the elevator car is stopped at a landing. In one example, the elevator system 20 is within a high rise building and the length of the roping arrangement 28 introduces challenges associated with maintaining the elevator car 22 at an intended vertical position especially when the elevator car 22 is at lower levels of the high rise building. The leveler 40 provides additional leveling control that enhances position control of the elevator car at an intended position for maintaining a desired alignment between a floor of the elevator car 22 and a corresponding landing floor. [00016] Figure 2 schematically illustrates an example leveler 40. In this example, the leveler comprises a rigid beam 42 that supports various components of the leveler 40. A rail climber arrangement 44 includes rollers in this example that are configured to move along the guide rails 24 so that the position of the leveler 40 is selectively adjustable relative to the guide rails 24. In this example, motors 46 provide a motive force for moving the rail climbers 44 and the leveler 40 along the guide rails 24. A controller 48 controls operation of the motors 46 to move the leveler 40 into a desired vertical position.

[oooi7] The controller 48 determines a desired position of the leveler 40 based upon an intended position of the elevator car 22 at a particular landing, for example. The controller 48 in one example communicates with the machine controller 30 to receive an indication of the intended vertical position of the elevator car 22. The controller 48 is suitably programmed to determine a corresponding desired position of the leveler 40 so that the leveler 40 can be moved into a position to facilitate maintaining the elevator car 22 at the selected position.

[00018] The illustrated example of Figure 2 includes a brake device 50 controlled by the controller 48.

[oooi9] In one example, the brake device 50 is utilized for selectively preventing movement of the leveler 40 relative to the guide rails 24. In such an example, the leveler 40 remains fixed in a desired position to provide a fixed support of the elevator car 22 to maintain the car in a corresponding desired position. In one such example, the motors 46 are controlled to prevent the rail climbers 44 from moving to provide a braking function.

[00020] In another example, the leveler 40 does not necessarily remain in a fixed position but, instead, moves to adjust the level of the elevator car 22 responsive to changes in the load on the car as passengers enter or leaver the car, for example. In such an example, the brake device 50 is used to reduce the duty cycle of the motors 46 by introducing a dead-band in the re-leveling logic.

[00021] The illustrated example includes a position detector 52 that provides position information to the controller 48 regarding a current vertical position of the leveler 40. The position detector 52 may take various forms. One example includes an encoder and tape or rope that operate similar to the PPT 32 of the example of Figure 1. Another example includes an optical detector that detects visible indicators along a guide rail 24 or another stationary element within a hoistway. The visible indicators are interpreted by the detector 52, the controller 48 or both for making a determination regarding an actual vertical position of the leveler 40. Given this description, those skilled in the art will realize how to arrange a controller and position detecting arrangement to meet the needs of their particular situation for obtaining position information regarding the leveler 40. [00022] The illustrated example includes resilient members 54 supported on the rigid beam 42 for engaging a portion of the frame of the elevator car 22. In this example, the leveler 40 is positioned within the hoistway to be underneath the elevator car 22 to provide support beneath the load on the elevator car for maintaining an intended position of the elevator car 22 so that a desired amount of correspondence between the elevator car floor and a landing floor can be maintained.

[00023] In one example, the resilient members 54 are stiff and have a low amount of resilience. In such an example the leveler 40 may be able to remain in one location while maintaining the elevator car 22 at a desired level. [00024] In another example, the resilient members 54 are compliant and have a relatively higher amount of resilience. In such an example, the resilient members 54 are more able to absorb loading associated with engagement between the leveler 40 and the car 22. in such an example , the detector 52 is configured to detect a position of the elevator car 22 and the controller 48 controls vertical motion of the leveler 40 to actively respond to changes in elevator car position responsive to any elevator car movement due to load changes.

[00025] In the example of Figure 2, the leveler 40 is moveable independently of the elevator car 22. The controller 48 in this example is configured to determine the position of the leveler 40, a desired position of the leveler 40 and to control operation of the motors 46, rail climbers 44 and brake device 50 to selectively move the leveler 40 as needed and to selectively maintain a vertical position of the leveler 40.

[00026] In one example, the machine controller 30 and the elevator machine 26 are responsible for the primary positioning of the elevator car 22. Known elevator car position techniques are used for directing the elevator car to an appropriate landing and parking the car at that landing in an intended position where the elevator car floor is expected to be appropriately aligned with the landing floor. The controller 48 and the leveler 40 are responsible for a secondary leveling or positioning function by determining an actual position of the leveler 40 when it is appropriately engaged with the elevator car 22. When the actual vertical position of the leveler 40 deviates from a desired position that corresponds to the intended position of the elevator car 22, the vertical position of the leveler 40 is selectively adjusted so that the position of the elevator car 22 can be adjusted when needed. The controller 48 in one example is programmed to know or determine the desired position of the leveler 40, which will have an expected relationship with the intended position of the elevator car based upon the configuration of the leveler and elevator car components, for example.

[00027] The leveler 40 and the controller 48 have a faster response time to changes in the car position compared to that of the machine controller 30 and the elevator machine 26. The controller 48 repeatedly determines the actual vertical position of the leveler 40 and determines whether that deviates from the desired position at a faster rate than the elevator machine controller 30 makes such a determination regarding the actual position of the elevator car 22 relative to the intended car position. The controller 48 has the ability to make such a determination more frequently to address potential changes in the position of the elevator car responsive to changes in the load on the car, for example, at lower levels of a high rise building. Additionally, the controller 48 and the leveler 40 are capable of making position adjustments with greater accuracy and within tighter tolerances compared to what may be possible if only using the machine controller 30 and the machine 26. The capability of the machine controller 30 and the machine 26 to maintain accurate elevator car position is compromised, in part, because of the extended length of the roping arrangement 28 as described above. With the leveler 40 and the controller 48, however, it is possible to more consistently maintain an intended position of the elevator car 22 at a landing. [00028] Figure 3 schematically shows another example arrangement of a leveler 40. In this example, a rope climbing arrangement is used for vertically moving the leveler 40 and for controlling the vertical position of it. In this example, climbing ropes 60 are secured in a selected position within a hoistway relative to the guider rails 24 so that the leveler 40 can be moved into selective engagement with the elevator car 22 as needed. This example includes wheels or sheaves 62 that are driven by motors 46 to cause the leveler 40 to ascend or descend along the climbing ropes 60. Otherwise, the example of Figure 3 operates consistent with the operation of the example of Figure 2.

[00029] The example of Figure 4 has a rail climber arrangement 44 similar to that of the example of Figure 2. A difference between the example of Figure 4 and Figure 2 is that instead of resilient members 54, this example includes locking members 70 that selectively lock the leveler 40 to the elevator car 22 so that they remain fixed relative to each other. In this example, the controller 48 controls the locking members 70 to lock onto an appropriate portion of the elevator car frame so that the leveler 40 remains fixed relative to the elevator car at least while the elevator car 22 is at a landing. When the elevator car 22 will travel to higher levels within a building where the secondary leveling function is not required, the locking members 70 are disengaged and the leveler 40 is independently moveable into a desired position. Otherwise, the example of Figure 4 operates like the example of Figure 2 for purposes of maintaining an intended vertical position of the elevator car 22.

[00030] In the examples of Figures 2-4, the leveler 40 is at least selectively moveable relative to the elevator car 22 independent of the elevator car 22. In such examples, the leveler 40 may be parked within an elevator pit or otherwise out of the way of desired movement of the elevator car 22 when not in use.

[00031] Figure 5 shows another example where the leveler 40 is supported on the structure of the elevator car 22. In this example, the leveler 40 is not moveable independent of the elevator car 22. Instead, it remains with the elevator car 22 throughout movement of the elevator car 22 along the guide rails 24. In this example, a rail climber arrangement 44 is used to provide a secondary leveling function for adjusting the position of the elevator car 22 as needed to maintain a desired alignment between the elevator car floor and a landing floor.

[00032] In the example of Figure 5, the rail climber arrangement 44 may be selectively disengaged from the guide rails 24 whenever the secondary leveling function is not required (e.g., while the elevator car 22 is traveling or positioned at a relatively high level within a building). In one example, the rail climber arrangement 44 is selectively engaged with the guide rails 24 while the elevator car 22 is moving and the motors 46 are used in a generator mode responsive to movement of rollers of the rail climber arrangement 44. Such an example allows for generating electrical power that may be used on board the elevator car 22, for example, or that may be stored to provide energy consumption savings as may be beneficial within the elevator system 20.

[00033] The various disclosed examples provide secondary or supplementary leveling control of an elevator car that facilitate maintaining an intended position of an elevator car to keep an elevator car floor aligned with a landing floor even within high rise or ultra high rise buildings.

[00034] The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this invention. The scope of legal protection given to this invention can only be determined by studying the following claims.

Claims

We claim: 1. A device for use in an elevator system, comprising: a leveler that is configured to move into and selectively maintain a vertical position in an elevator hoistway; a controller that is configured to determine a desired vertical position of the leveler based upon a corresponding intended position of an elevator car and configured to adjust a vertical position of the leveler responsive to a difference between an actual vertical position of the leveler and the desired vertical position.

2. The device of claim 1, wherein the leveler comprises a rail climber that is configured to move along a guide rail.

3. The device of claim 1, wherein the leveler comprises a roper climber that is configured to move along a rope.

4. The device of claim 1, wherein the leveler comprises at least one rigid beam.

5. The device of claim 4, comprising a resilient member supported on the rigid beam and positioned to engage an elevator car such that the resilient member is between the rigid beam and an elevator car.

6. The device of claim 5, wherein the resilient member comprises a coil spring.

7. The device of claim 1, comprising a locking member that is positioned to engage and lock onto an elevator car such that the leveler and the elevator car remain fixed relative to each other.

8. The device of claim 1, wherein the controller is configured to communicate with a machine controller that is responsible for controlling a position of an elevator car and determine the desired position of the leveler responsive to information from the machine controller.

9. The device of claim 8, comprising a detector that is configured to detect the actual position of the leveler and to provide an indication of the actual position to the controller, wherein the controller adjusts the position of the leveler responsive to a difference between the indicated actual position and the desired position.

10. The device of claim 1, comprising an elevator car; and a machine controller configured to control a position of the elevator car, the controller determining the desired position of the leveler based on an indication of the intended position of the elevator car from the machine controller and determining the actual position of the leveler independent of the machine controller.

11. The device of claim 10, wherein the leveler comprises a motor that generates a force for moving the leveler that is sufficient to move the elevator car with the leveler.

12. The device of claim 10, wherein the leveler is moveable relative to the elevator car for selectively engaging the elevator car.

13. The device of claim 12, wherein the leveler is positioned beneath the elevator car.

14. The device of claim 10, wherein the leveler is connected to a frame member of the elevator car such that the leveler moves with the elevator car.

15. A method of controlling a position of an elevator car in an elevator system including a machine controller configured to control a position of the elevator car and a leveler that is at least selectively associated with the elevator car, comprising the steps of: determining an intended position of the elevator car; moving the elevator car to the intended position using the machine controller; moving the leveler into a desired vertical position corresponding to the intended position where the leveler provides support for maintaining the elevator car in the intended position; and selectively adjusting a vertical position of the leveler responsive to a difference between the desired vertical position and an actual position of the leveler.

16. The method of claim 15, comprising positioning the leveler beneath the elevator car; and adjusting the position of the leveler using a force sufficient to lift the elevator car to the intended position as the leveler moves into the desired position.

17. The method of claim 15, comprising determining the actual position of the leveler independent of determining an actual position of the elevator car.

18. The method of claim 15, comprising periodically determining the actual position of the leveler more frequently than determining an actual position of the elevator car.

19. The method of claim 15, comprising updating the position of the elevator car at a first update rate using the machine controller responsive to a difference between an actual position of the elevator car and the intended position; and performing the adjusting of the position of the leveler at a second, faster update rate.

20. The method of claim 15, comprising coupling the leveler to the elevator car such that the leveler remains fixed relative to the elevator car.

21. An elevator system, comprising: a car; a roping arrangement secured to said car; a motor for moving said roping arrangement; and a leveler located adjacent said elevator car to relevel said elevator car.

22. The elevator system of claim 21, wherein said motor includes a controller to relevel said car

23. The elevator system of claim 22, wherein said controller provides primary relevel control.

24. The elevator system of claim 21, wherein said leveler is autonomous from said elevator car.

25. The elevator system of claim 21, wherein said leveler attaches to said elevator car.