HK1163642B

HK1163642B - Elevator car positioning using a vibration damper

Info

Publication number: HK1163642B
Application number: HK12104340.5A
Authority: HK
Inventors: Randall Keith Roberts; Leandre Adifon
Original assignee: Otis Elevator Company
Filing date: 2008-12-05
Publication date: 2017-03-31

Description

Elevator car positioning using vibration dampers

Background

Elevator systems include, for example, an elevator car that moves between multiple landings to provide elevator service to different levels within a building. The machine includes a motor and brake for selectively moving the elevator car to a desired position and thereafter holding 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 the selected landing in a known manner.

One challenge associated with elevator systems is maintaining the car at a suitable height relative to the landing to facilitate simple passage between the elevator car and the doorway where the elevator car resides. Ideally, the car floor remains flush with the landing floor to simplify movement of passengers between the doorway and the elevator car while reducing the chance of someone tripping over. Existing elevator codes define a displacement threshold that establishes the maximum gap allowed between the landing floor and the elevator car floor. When the distance exceeds the encoding threshold, the elevator system must re-level or correct the position of the elevator car.

Conventional elevator re-leveling measures include sensing the amount of car displacement to the ground. This is typically accomplished by using an encoder on the primary position sensor or other rotating component associated with the elevator car. When the displacement exceeds a set threshold, the re-leveling process is started. The machine controller makes a determination regarding the weight of the car and pre-torques the motor used to lift the car before releasing the machine brake. The motor current is then controlled using a fixed gain feedback compensator for the position error.

Conventional measures for re-leveling elevator cars perform well in most cases. For example, in some high-rise buildings above 120m, conventional measures may not provide satisfactory results. This occurs in part because the effective stiffness of the elevator roping members decreases proportionally with their length. Thus, a longer elevator roping arrangement allows the amount of static deformation to be increased in response to varying loads on the elevator car due to, for example, passengers entering or leaving the car. Additionally, there is a time lag between motor actuation, car reaction, and position sensor response. Such hysteresis introduces potential stability problems in the position feedback logic associated with conventional approaches. Another problem is that the reduced roping arrangement stiffness reduces the resonance frequency associated with the elevator car bouncing caused by load variations on the car. This lower frequency resonance places a limit on the conventional control logic gain, which limits the bandwidth and therefore performance.

Disclosure of Invention

An exemplary method of controlling elevator car position includes determining that an elevator car needs to be re-leveled and determining whether a vibration damper is activated. If the vibration damper is activated, a gain for re-leveling for controlling operation of a motor responsible for moving the elevator car is adjusted.

An exemplary elevator system includes a vibration damper configured to resist vertical movement of an associated elevator car. A controller device controls a motor configured to move an associated elevator car. The controller means comprises a velocity servo system having a gain with a set reference value. The controller device is configured to selectively adjust the gain of the velocity servo system from the set reference value during re-leveling of the associated elevator car if the vibration damper is activated.

The various features and advantages of this invention 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.

Drawings

Figure 1 schematically illustrates selected portions of an example elevator system.

Fig. 2 schematically illustrates an exemplary vibration damper arrangement.

FIG. 3 schematically illustrates another example vibration damper.

FIG. 4 schematically illustrates another example vibration damper.

Fig. 5 schematically illustrates an exemplary elevator control arrangement.

Detailed Description

Fig. 1 schematically illustrates selected portions of an exemplary elevator system 20. The elevator car 22 is supported for movement along guide rails 24 in response to operation of an elevator machine 26. In this example, the elevator machine 26 is responsible for controlling movement of the roping arrangement 28 that supports the weight of the elevator car 22 and the counterweight 29. The roping arrangement can include any known roping ratio, such as a conventional 1: 1 or 2: 1 roping system, for example. The motors and brakes of the machine 26 operate in response to the elevator machine controller 30 to achieve the desired movement and positioning of the elevator car 22.

The controller 30 uses information regarding the operation of the machine 26 and information regarding the position of the elevator car 22 to determine how to control the machine 26 to achieve the desired elevator system operation. The example of fig. 1 includes a primary position sensor 32 that provides information to the controller 30 regarding the position of the elevator car 22. For example, the primary position sensor 32 includes a code wheel and a rope or belt that moves with the elevator car 22 such that the code wheel provides information to the controller 30 indicative of the current position of the elevator car. The information regarding the position of the elevator car 22 may be determined in any known manner.

Controller 30 includes a speed servo system for controlling the operation of the motors of machine 26. The speed servo system has a re-leveling gain (K) that controls a motor torque signal provided to a motor of the machine 26_rl) And ratio (K)_p) Integral (K)_i) And (4) gain. The speed servo gain is set in a known manner in most cases to provide the desired elevator system performance.

In some situations, the elevator car 22 will have to be re-leveled when the elevator car 22 stops at a landing. In the case of a high-rise building, the extended haul arrangement 28 length introduces additional control challenges when the elevator car 22 is at a relatively low landing, as previously described. The exemplary controller 30 utilizes the adjusted speed servo gain to achieve the desired re-leveling performance when the elevator car 22 is at a landing that may not provide the desired results with conventional re-leveling techniques alone.

The illustrated example includes at least one vibration damper 40 supported for movement with the elevator car 22. The vibration dampers 40 in this example are supported on each side of the elevator car 22. The vibration damper 40 is configured to engage a stationary surface when the elevator car 22 is stopped at a landing to inhibit vertical movement of the elevator car 22 under such conditions. In the depicted example, the vibration dampers 40 are used during a re-leveling procedure. For such purposes, the vibration damper 40 is considered a leveling vibration damper because it dampens vibrations during elevator car leveling.

Fig. 2 schematically illustrates an exemplary vibration damper configuration. The vibration dampers 40 in this example are activated in response to the elevator car doors 42 moving from a closed position (shown in phantom) to an open position. A triggering mechanism 44, such as a switch or detector, provides an indication when the elevator car door 42 is moved to the open position. There are known techniques for determining when an elevator door is open, and some examples use such techniques. This open elevator car door is interpreted as an indication that the elevator car 22 is at a landing, when it is desired to at least temporarily hold the elevator car. In some cases, it may be advantageous to also require the inclusion of a ground landing detection signal in the vibration damping control system logic so that it is only used at the lowest floors in a high-rise elevator system, where extended rope lengths between the car and the machine near the top of the hoistway compromise traditional re-leveling control system performance. In one such example, the door detection device 44 and the ground detection device must both be activated to enable engagement of the vibration damper.

The actuator 46 moves the friction member 48 into engagement with the surface on the guide rail 24 in response to an indication that the elevator car door 42 is open (and that the ground detector is activated if utilized). In one embodiment, the frictional engagement between the friction members 48 and the guide rails 24 serves to resist vertical movement of the elevator car 22 when the elevator car 22 is resting at a landing. Resisting vertical movement in this example is distinguished from stopping all such movement. For example, the vibration dampers 40 reduce vibrations associated with load changes in the elevator car 22 during loading or unloading of passengers. The reduction in vibration in this example has no effect of securing the elevator car 22 to the landing or rail 24 during loading and unloading of passengers.

Fig. 3 diagrammatically illustrates an exemplary vibration damper 40. In this example, mounting brackets 50 and 52 are provided for securing the vibration damper 40 in a selected position relative to the elevator car 22. The actuator 46 controls movement of the arm 54 to selectively move the friction member 48 into and out of engagement with a stationary surface, such as a corresponding surface of the rail 24. In the illustrated example, the friction member 48 is pivotally supported relative to the arm 54 such that it can pivot about a pivot axis 56. The pivotal movement of the friction member 48 compensates for any misalignment between the engaging surface of the friction member 48 and the orientation of the surface on the rail 24 engaged by the friction member 48.

The present example also includes a mechanical spring 58 for controlling the amount of pressure applied by the friction member 48 to the guide rail surface. Exemplary actuators 46 include solenoids and motors. The size of the spring 58 and the force provided by the actuator 46 provide sufficient frictional engagement between the friction member 48 and the stationary surface to provide sufficient vertical damping force for resisting vertical movement of the elevator car 22. The actuator 46 in one example comprises a screw that is movable in a linear direction in response to a rotational motion.

FIG. 4 diagrammatically illustrates another exemplary vibration damper 40. In this example, the actuator 46 moves the first arm 60. A pivot linkage 62 is coupled to the first arm 60. The pivot linkage 62 pivots about a pivot point 64, the pivot point 64 remaining stationary relative to the mounting bracket 50 in this example. The pivot point 64 is located near one end of the pivot link 62. The opposite end 66 of the pivot link 62 is coupled to the arm 54, which arm 54 is referred to in this example as the second arm.

As the actuator 42 moves the first arm 60, the pivot link 62 pivots, causing the second arm 54 and the friction member 48 to move into or out of engagement with a stationary surface, such as a surface on the rail 24. This example includes a mounting plate 68 and a guide surface 70 for guiding the movement of the friction member 48. In this example, the friction member 48 is supported for pivotal movement about a pivot axis 56. The pivot axis 56 moves with the plate 68 (e.g., from left to right in the figure) such that the friction member 48 moves with the plate 68 and relative to the plate 68.

The use of the pivot link 62 allows for increased movement of the damping pad available from operation of the actuator 42 without requiring an increase in the size or power of the actuator 42. The example of fig. 4 includes a return spring 72 that urges the second end 66 of the pivot link 62 in a direction to move the friction member 48 out of engagement with a respective one of the rails 24 when the actuator is closed or no force is applied to the first arm 60.

The example vibration dampers 40 may be used to dampen vertical movement or vibration of the elevator car 22 during a re-leveling run. The vibration dampers 40 allow for improved motor control to achieve improved re-leveling performance. For example, it is possible to use the increased gain for the motor torque command during the re-leveling procedure to control the operation of the motor 26. This allows increasing the bandwidth of the dynamic position control system. Without the vibration damper 40, the resonant frequency of the elevator roping arrangement 28 may be undesirably excited, for example, when increased gain for motor control is used. When the vibration dampers 40 are activated (i.e., the friction members 48 are moved into engagement with the guide rails 24), the example controller 30 adjusts the gains for motor control during re-leveling.

Fig. 5 schematically illustrates an exemplary elevator control arrangement, wherein a portion of controller 30 is schematically represented. In this example, conventional elevator motor control techniques are used to provide control signals to operate the motor of the machine 26 under most elevator system operating conditions. When re-leveling is required and the vibration dampers 40 are activated, the gains associated with the motor control are adjusted to provide the desired re-leveling performance.

In fig. 5, a desired elevator car position input 152 is compared to an actual elevator car position indication 154 using a comparator 156. The output of the comparator 156 (i.e., any difference between the actual and desired positions of the elevator car) is processed by a re-leveling gain module 158. In one example, the re-leveling gain is adjusted depending on whether the vibration dampers 40 are activated. The output of the re-leveling gain module 158 is compared to the primary speed sensor input 160 in a comparator 162.

The output of comparator 162 is provided to a velocity servo 166. If the vibration dampers 40 are activated, the control in this example adjusts the re-leveling gain and the velocity servo gain (K) for the motor torque signal_pAnd K_i) At least one of (a). In one example, the control increases at least one of the gains to a value higher than a set reference value of the gain. For example, in the illustrated example, all gains are added to improve re-leveling performance.

In one example, a first leveling gain value is used during a re-leveling procedure when the vibration dampers 40 are not activated, and a second, different leveling gain is used when the vibration dampers 40 are activated. In this example, the second gain is higher than the first gain.

In this example, these gains are increased when the vibration dampers 40 are activated to dampen vertical movement of the elevator car 22. This increased gain provides improved performance during re-leveling of the elevator car 22. The speed servo 66 provides a motor torque signal output 68 for controlling the motors of the machine 26 during re-leveling. For example, using a higher gain for motor torque allows for faster re-leveling. Another example improves re-leveling by achieving a reduced magnitude of vertical correction of elevator car position.

If the gain(s) are increased without the vibration dampers 40 being activated to resist vertical movement of the elevator car 22, it will be possible to excite the resonant frequency of the elevator roping arrangement 28, which will introduce vibrations or bouncing of the elevator car, for example. The use of the vibration dampers 40 during the re-leveling procedure allows the re-leveling gain and the velocity servo gain to be adjusted to provide improved re-leveling performance while avoiding energizing hoistway components. The additional elevator car position control provided by the vibration dampers 40 effectively reduces excitation of elevator vertical vibration modes while still allowing higher speed servo gain and improved re-leveling.

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

1. A method of controlling elevator car position, comprising:

determining that the elevator car needs to be re-leveled from a current vertical position to a desired vertical position;

determining whether a vibration damper is activated; and

adjusting a gain for the re-leveling for controlling operation of a motor responsible for moving the elevator car vertically along a hoistway if the vibration damper is activated.

2. The method of claim 1, comprising

Generating a motor torque signal for controlling the motor for moving the elevator car using the adjusted gain to accomplish the re-leveling.

3. The method of claim 1, comprising

Using the adjusted gain when moving the elevator car during re-leveling; and

different default gains are used during other elevator operating conditions.

4. The method of claim 1, comprising

Using a first gain if the vibration damper is not activated; and

a different second gain is used if the vibration damper is activated.

5. The method of claim 4, wherein the second gain has a value higher than the first gain.

6. The method of claim 1, wherein the adjusted gain is at least one of a re-leveling gain or a proportional-integral gain of a speed servo associated with the motor.

7. The method of claim 1, comprising

The vibration damper is activated in response to the elevator car door opening.

8. The method of claim 7, wherein the vibration damper includes an actuator and a friction member movable by the actuator to a position engaging a stationary surface to limit an amount of vertical movement of the elevator car during the re-leveling.

9. The method of claim 8, wherein the actuator moves the friction member in a first direction and the friction member is supported for pivotal movement relative to the first direction.

10. The method of claim 8, wherein the vibration damper comprises:

a first arm moved by the actuator;

a pivot link coupled to the first arm to pivotally move about a pivot axis near one end of the pivot link in response to movement of the first arm; and

a second arm coupled to the pivot link near an opposite end of the pivot link such that the second arm moves in response to movement of the pivot link, the friction member being supported for movement with the second arm and for pivotal movement relative to a direction of movement of the second arm.

11. An elevator positioning system comprising:

a vibration damper configured to resist vertical movement of an associated elevator car; and

a controller device for controlling a motor configured to move the associated elevator car vertically along a hoistway, the controller device having a gain with a set point, the controller device configured to selectively adjust the gain from the set point during re-leveling of the associated elevator car from a current vertical position to a desired vertical position if the vibration damper is activated.

12. The elevator positioning system of claim 11, wherein the controller device increases the gain to a second recalibration value that is higher than the set value if the vibration damper is activated.

13. The elevator positioning system of claim 11, wherein the controller means generates a motor torque signal using the adjusted gain.

14. The elevator positioning system of claim 13 wherein the controller means generates a motor torque signal using an adjusted gain for re-leveling an elevator car if the vibration damper is activated and otherwise uses the set point for gain.

15. The elevator positioning system of claim 11, wherein the gain is at least one of a re-leveling gain or a proportional-integral gain of a velocity servo.

16. The elevator positioning system of claim 11, wherein the vibration damper is configured to be activated in response to opening of a door of the associated elevator car.

17. The elevator positioning system of claim 11, wherein the vibration damper comprises:

an actuator;

a friction member supported for movement by the actuator in a first direction to a position of engagement with a stationary surface, the friction member supported for pivotal movement relative to the first direction.

18. The elevator positioning system of claim 17, wherein the vibration damper comprises:

a first arm moved by the actuator;

19. The elevator positioning system of claim 11, comprising:

an elevator car having the vibration damper supported on a portion of the elevator car;

a roping arrangement secured to the elevator car; and

a motor for moving the roping arrangement such that the elevator car moves in response to the controller device.