HK1175450B - Elevator system with magnetic braking device - Google Patents

Description

Elevator system with magnetic braking device

Background

Elevator systems include a variety of devices for controlling the speed of movement of an elevator car. The elevator machine operates in response to a controller that dictates the speed of movement of the car. The elevator machine brake applies a braking force at the machine location, e.g. to decelerate the car and keep the car stable at the landing. An additional braking device is provided on the elevator car.

In some situations, the elevator car may move at a speed that exceeds a desired limit. In such an overspeed condition, a braking device on the car is activated to stop the car. Such braking devices typically include friction pads that engage guide rails along which the elevator car travels. One drawback associated with such braking devices is that the engagement between the friction pad and the rail tends to cause surface deformation along the corresponding portion of the rail. Any variations on the surface of the guide rails tend to introduce vibrations and potential noise during subsequent elevator operation, thereby reducing ride quality.

SUMMARY

An exemplary elevator system includes an elevator car positioned to move along at least one guide rail. At least one braking device is supported for movement with the elevator car. The braking device includes a plurality of magnet members and a plurality of cooperating members. The cooperating member is selectively movable relative to the magnet member between a first position and a second position. In the first position, the elevator car is allowed to move along the guide rails. In the second position, the magnet member and the cooperating member cooperate to cause an electromagnetic interaction between the braking device and the guide rail to inhibit movement of the elevator car along the guide rail.

Various features and advantages of the disclosed example embodiments 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 Drawings

Figure 1 schematically illustrates selected portions of an elevator system designed according to one embodiment of this invention.

FIG. 2 schematically illustrates an example brake configuration.

FIG. 3 is an end view schematically illustrating an example brake device embodiment.

Fig. 4A and 4B schematically illustrate an example brake device in two different operating conditions.

Fig. 5A and 5B schematically illustrate another example brake device in two operating conditions.

Fig. 6A and 6B schematically show another brake arrangement in two operating conditions.

Fig. 7A, 7B, and 7C schematically illustrate another example brake arrangement.

FIG. 8 schematically illustrates another example brake arrangement.

FIG. 9 schematically illustrates another example brake arrangement.

Detailed Description

Fig. 1 schematically illustrates selected portions of an example elevator system 20. An elevator car assembly 22 is positioned for movement along guide rails 24. The car assembly 22 includes an elevator car 26 and a braking device 30 supported for movement with the elevator car 26 along the guide rails 24. The braking device 30 utilizes the electromagnetic response in the guide rails 24 to apply a braking force to prevent movement of the elevator car 26 along the guide rails 24.

Fig. 2 shows an example braking device 30 that includes a mounting plate 32 secured to an appropriate portion of the elevator car 26, such as the car frame. A first support bracket 34 is secured to the mounting plate 32. The plurality of magnet members 36 are supported on a first backing plate 38, the first backing plate 38 being secured to the support 34. In one example, magnet component 36 comprises a permanent magnet and backing plate 38 comprises iron or another ferromagnetic material.

The other bracket 40 supports a slide 42, which slide 42 is selectively movable relative to the bracket 40. In this example, a linear bearing 44 is provided to facilitate linear movement of the slider 42 relative to the bracket 40 in a direction parallel to the vertical path followed by the elevator car. A plurality of cooperating members 46 are supported on a second backing plate 48, the second backing plate 48 being attached to the slide 42. The cooperating member 46 is selectively movable relative to the magnet member 36 when the slide 42 moves linearly relative to the bracket 40.

As can be appreciated from fig. 3, for example, the guide rails 24 each comprise a fin 50, the fin 50 being received between the magnet part 36 and the co-acting part 46 such that there is a gap 51 between them. In this orientation, the brake 30 is able to move along the rail 24 without any contact with the surface on the fin 50.

When the cooperating member 46 is in the first position relative to the magnet member 36, the brake device 30 is in the inactive state when the brake device 30 is not being used to apply a braking force. In other words, when the cooperating member 46 is in the first position relative to the magnet member 36, the elevator car 26 is permitted to move along the guide rail 24.

When the cooperating member 46 is moved to a second position relative to the magnet member 36, the magnet member 36 and the cooperating member 46 cooperate to cause an electromagnetic interaction between the guide rail and the braking device to inhibit movement of the elevator car along the guide rail. The electromagnetic response in the guide rails 24 generates an electric braking force that resists movement of the elevator car 26 along the guide rails 24. In one example, the electromagnetic response includes eddy currents induced in the fins 50 of the rail 24.

The rail 24 comprises an electrically conductive material to facilitate application of a braking force by the braking device 30. In one example, the rails 24 comprise aluminum. One feature of using aluminum for the guide rails is that it allows for a lighter weight material (e.g., aluminum is lighter than iron), which provides savings during installation compared to conventional elevator arrangements. Lighter rails facilitate cheaper installation. A lighter material such as aluminum can be used in this arrangement because no frictional engagement is required between the brake 30 and the rail surface for inhibiting movement of the elevator car 26 under selected conditions. If friction is to be used, the aluminum rail may include a hardened surface for durability.

Fig. 4A schematically illustrates one example arrangement of the braking device 30. In this example, the plurality of magnet members 36 are all arranged on one side of the fin 50 of the guide rail 24. In the present example, the co-acting part 46 comprises a permanent magnet. The rail fin 50 is positioned in the gap between the magnet part 36 and the permanent magnet cooperating part 46. The magnetization or polarization directions of the magnets in fig. 4A are opposite to each other on opposite sides of the orbiting fin 50. This is schematically shown by arrow 52. The first position of the cooperating member 46 shown in fig. 4A corresponds to the deactivated state of the braking device 30 when the elevator car 26 is permitted to move along the guide rails 24.

Fig. 4B schematically shows the example of fig. 4A in an activated state. For example, an active brake application state is useful during an elevator overspeed condition. The slide 42 and the co-operating member 46 have been moved as schematically indicated by arrow 53 (i.e. to the left according to the drawing). In the second position shown in fig. 4B, the permanent magnet cooperating part 46 has a magnetization direction that is aligned with the magnetization direction of the magnet part 36 directly opposite the rail fin 50. In this position, the electromagnetic interaction between the guide rails 24 and the braking device 30 generates a braking force that resists movement of the elevator car 26. In the second position of fig. 4B, the magnet assemblies are positioned relative to each other such that their aligned polarizations force the magnetic field flow across the gap between them through the guide rail fins 50. The penetrating magnetic field excites eddy currents in the rail, thereby generating high electrodynamic braking forces. The way in which eddy currents excited in the rail generate an electric braking force is known.

By selectively controlling when the slide 42 and cooperating member 46 move to the second position shown in fig. 4B, the braking device 30 selectively applies a braking force to prevent movement of the elevator car 26.

One feature of the example shown in fig. 4A and 4B is that even in the non-activated state when the cooperating member 46 is in the first position shown in fig. 4A, a small portion of the magnetic field (e.g., the stray field) penetrates the rail fin 50 and generates a relatively small drag force during elevator operation. Such a drag force may be about three percent of the force associated with blocking movement of the elevator car when the cooperating member 46 is in the second position. This small drag force can be used as a damping force to minimize vertical vibration of the elevator car 26. Furthermore, the leakage magnetic field penetrating the rails provides lateral stability or centering forces during elevator operation when the cooperating member 46 is in the first position. In other words, the arrangement schematically shown in fig. 4A and 4B provides a vibration reduction feature that improves elevator ride quality despite not using the braking device 30 to slow down the elevator car.

Fig. 5A and 5B schematically illustrate another example brake apparatus 30. In the present example, the co-acting member 46 comprises a pole shoe made of ferromagnetic material. The slider 42 and pole shoe cooperating member 46 are on the same side of the rail fin 50 as the magnet member 36. In this example, a return iron shim plate 48 is provided on the opposite side of the rail fin 50.

When the pole-piece cooperating member 46 is in the first position shown in fig. 5A, the magnetic field of the magnet member 36 is substantially constrained to one side of the rail fin 50. In this first position, the pole shoe cooperating members 46 are at least partially aligned with the spaces 56 between the magnet members 36. The present example also includes spaces 58 between the pole shoe cooperating members 46.

As shown in fig. 5B, the slide 42 is movable as schematically shown by arrow 60 to position the pole shoe cooperating member 46 in a second position relative to the magnet member 46. In this position, the pole shoe cooperating members 46 are aligned with the magnet members 36, allowing the magnetic field to penetrate the rail fins 50 in a manner that excites eddy currents in the rail fins 50 to generate a sufficiently high electric braking force to resist movement of the elevator car 26. In the position shown in fig. 5B, the magnetic field of the magnet flows from the magnet assembly 36 through the rail fin 50 to the iron shim plate 48 on the opposite side of the rail fin 50 and back to the magnet assembly 36.

By selectively controlling the position of the slide 42 and the pole shoe cooperating member 46, the braking device 30 selectively applies a braking force to resist movement of the elevator car 26. In the example shown, the magnet members 36 each have a width. The spacing 56 between magnet features 36 and the width of each magnet feature 36 collectively establish a pole pitch 61. The dimensions of the cooperating members 46 and the spaces 58 therebetween are selected such that in the second position shown in figure 5B, the spaces 58 are aligned with the spaces 56 and the pole shoe cooperating members 46 are aligned with the magnet members 36. Between a first position shown in fig. 5A and a second position shown in fig. 5B, slide 42 has moved a distance corresponding to half of pole pitch 61.

Fig. 6A and 6B show another example arrangement in which magnet members 36 are provided on both sides of the rail fin 50, and pole shoe cooperating members 46 are associated with respective sets of magnet members 36. In the first position shown in fig. 6A, the magnetic field of the magnet assembly 36 does not penetrate the rail fin 50. In the second position shown in fig. 6B, after the cooperating member 46 has moved in a straight line as schematically shown by arrow 62, the magnetic field of the magnet member 36 penetrates the rail fin 50 in a manner that excites eddy currents in the rail fin 50 to generate an electrodynamic braking force.

Fig. 7A-7C schematically illustrate another example embodiment. In this example, the guide rail 24 comprises two rail fin portions 50, and the braking device 30 is arranged to interact with both of them. The use of two rail fins 50 increases the surface area of the conductive material within which eddy currents may be induced. The configuration including two rail fins 50 also reduces the impedance along the eddy current path. One feature of this arrangement is that it allows the size of the rail fin 50 to be reduced in the direction extending from the hoistway wall toward the center of the elevator car 26. For example, reducing the size of the rail fins required allows for increasing the amount of space available for the elevator car within the hoistway or for reducing the amount of hoistway space required for a particular elevator car capacity.

Fig. 7B shows the co-acting part 46 in a first position relative to the magnet part 36. In this example, the slider 42, the cooperating member 46 and the magnet member 36 are all positioned in the space between the two rail fins 50. A return iron shim plate 38 is provided on the opposite side of each rail fin 50. In the present example, the co-acting part 46 comprises a permanent magnet. The magnet assemblies 36 are spaced apart with the pole pieces 66 between the magnet assemblies 36. The permanent magnet parts 46 are spaced apart by pole pieces 68 between the permanent magnet co-acting parts 46. In the arrangement of fig. 7B, the magnetization or polarization directions of the magnet feature 36 and the immediately adjacent or aligned magnet cooperating feature 46 are arranged such that they are in opposite directions as schematically shown by arrows 70. In this position, substantially all of the magnetic fields of the magnet assembly 36 and cooperating magnet assembly 46 are confined within the space between the two rail fins 50. This allows the elevator car to move along the guide rails 24.

When it is desired to apply the brake, the slide 42 is moved as schematically shown by arrow 72 to move the magnet cooperating member 46 linearly relative to the magnet member 36 to the second position shown in fig. 7C. In this position, the magnetization directions of the magnet member 36 and the immediately adjacent or directly aligned magnet cooperating member 46 are the same as schematically shown by arrow 70. This orientation of the magnetization directions and the presence of the pole members 66 and 68 therebetween allows the magnetic fields of the magnets to penetrate the rail fins 50, thereby exciting eddy currents in them to generate an electrodynamic braking force.

One feature of electric braking force as used in the above example is that the amount of force is proportional to the speed at which the magnet member 36 and cooperating member 46 move relative to the rail fin 50. The braking force is greatest at the highest movement speed and decreases as the elevator car 26 slows. In some examples, the braking device 30 does not rely solely on the electric braking force described above to completely stop the elevator car 26. In situations where the hoistway friction system forces are less than the gravitational and inertial forces that tend to push the elevator car 24, additional frictional braking may be desired to stop the elevator car at a desired location.

One example allows the use of the structure of the brake device 30 to apply additional frictional braking force. Fig. 8 schematically shows an arrangement in which the magnet assembly 36 includes a braking material 76 supported on the magnet assembly and facing the rail fin 50. Once the electrical braking force has been used to sufficiently slow the elevator car, the back pad component 38 and the magnet component 36 are moved toward the rail fins 50 such that the braking material 76 contacts the rail fins 50 to provide additional frictional braking force to completely stop the elevator car 26.

Fig. 9 schematically shows another arrangement in which the brake pad 78 is arranged adjacent the magnet assembly 36. The brake pads 78 are selectively moved into engagement with the rail fins 50 to fully stop the elevator car under selected conditions.

In one example, the movement of the braking material 76 or braking pad 78 into engagement with the rail fin 50 is due to a magnetic force between the magnet member 36 and the cooperating member 46. In other words, the magnetic attraction (or repulsion) between portions of the example braking device 30 can be used to move the friction stop member into engagement with the rail fin 50 to prevent any movement of the elevator car.

In one example, the manner in which the magnet members 36, the cooperating members 46, or both are supported allows the material to deflect such that, under selected conditions, the corresponding member moves toward the rail fin 50 to eliminate a gap between the rail fin 50 and the corresponding friction braking member. In another example, suitable portions of the brake device 30 are configured to allow corresponding portions of the device 30 to move laterally to allow the friction braking components to selectively engage the rail fins 50.

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 scope of legal protection given to this invention, which can only be determined by studying the following claims.

Claims (19)

1. An elevator system comprising:

an elevator car;

at least one guide rail positioned to guide movement of the elevator car; and

at least one braking device supported on the elevator car for movement with the elevator car, the braking device including a plurality of magnet members adjacent the guide rail and a plurality of cooperating members adjacent the magnet members, the cooperating members being movable relative to the magnet members between a first position in which the braking device permits movement of the elevator car along the guide rail and a second position in which the magnet members cooperate with the cooperating members to cause an electromagnetic interaction between the guide rail and the braking device to inhibit movement of the elevator car along the guide rail;

wherein the magnet parts are arranged along a straight line with a first space between each magnet part and an adjacent magnet part;

the co-acting parts are arranged along a straight line with a second space between each co-acting part and an adjacent co-acting part;

the first position comprises the cooperating member at least partially aligned with the first space, and the magnet member at least partially aligned with the second space; and is

The second position includes the cooperating member aligned with the magnet member and the first space aligned with the second space.

2. The elevator system of claim 1, wherein the magnet component and the cooperating component are both on a single side of the guide rail.

3. The elevator system of claim 1, wherein the magnet component is on one side of the guide rail and the cooperating component is on a second side of the guide rail.

4. The elevator system of claim 1, wherein the detent includes a base on which the magnet component is supported and a slide on which the cooperating component is supported to slide between the first position and the second position.

5. The elevator system of claim 1, wherein the cooperating member moves from the first position to the second position in response to the elevator car moving at a speed that exceeds a selected threshold.

6. Elevator system according to claim 1,

the magnet part has a certain width and is provided with a magnet part,

the distance across one of the first spaces plus the width of one of the magnet parts is equal to a first pitch, and

the cooperating member moves a distance equal to half the first pitch when moving from the first position to the second position.

7. The elevator system of claim 1, wherein the cooperating member moves in a direction parallel to a direction of movement of the elevator car when the cooperating member moves between the first position and the second position.

8. Elevator system according to claim 1,

the at least one guide rail comprises two parallel rail fins, and

the braking device is at least partially between the parallel rail fins such that there is an electromagnetic interaction between the braking device and both of the parallel rail fins.

9. The elevator system of claim 8, wherein the magnet component and the cooperating component are disposed between the parallel rail fins.

10. Elevator system according to claim 1,

the magnet part is on one side of the guide rail,

the cooperating parts comprise magnets on opposite sides of the guide rail,

the first position comprises the magnet part and the co-acting part being aligned with each other such that the magnetization direction of the magnet part relative to the guide rail is opposite to the magnetization direction of the correspondingly aligned co-acting part, and

the second position comprises the magnet part and the co-acting part being aligned with each other such that the magnetization direction of the magnet part relative to the guide rail is the same as the magnetization direction of the correspondingly aligned co-acting part.

11. Elevator system according to claim 10,

the magnetization direction of each magnet part is opposite to the magnetization direction of an immediately adjacent one of the magnet parts, and

the magnetization direction of each cooperating part is opposite to the magnetization direction of an immediately adjacent one of said cooperating parts.

12. The elevator system of claim 1, wherein at least some of the magnet components are movable in a direction toward the guide rail to move braking material into engagement with the guide rail.

13. The elevator system of claim 1, comprising a friction braking member positioned between at least two of the magnet members to engage the guide rail.

14. The elevator system of claim 1, comprising a brake pad supported on a surface of at least some of the magnet components facing the guide rail to selectively engage the guide rail.

15. The elevator system of claim 1, wherein the cooperating component comprises a magnet.

16. The elevator system of claim 1, wherein the cooperating members comprise magnetic poles.

17. A method of controlling the speed of an elevator car having a detent supported on the elevator car for movement with the elevator car, the detent including a plurality of magnet members adjacent guide rails and a plurality of cooperating members proximate the magnet members, wherein the magnet members are arranged along a line with a first space between each magnet member and an adjacent magnet member and the cooperating members are arranged along a line with a second space between each cooperating member and an adjacent cooperating member, the method comprising the steps of:

holding the cooperating member in a first position relative to the magnet member such that the braking device allows movement of the elevator car along the guide rail, wherein the first position includes the cooperating member at least partially aligned with the first space and the magnet member at least partially aligned with the second space; and

selectively moving the cooperating member to a second position in which the magnet member and the cooperating member cooperate to cause an electromagnetic interaction between the guide rail and the detent to prevent movement of the elevator car along the guide rail when a reduction in elevator car speed is desired, wherein the second position includes the cooperating member aligned with the magnet member and the first space aligned with the second space.

18. The method of claim 17, wherein the method comprises: moving the cooperating member from the first position to the second position in response to the elevator car moving at a speed that exceeds a selected threshold.

19. The method of claim 17, wherein the method comprises: applying a frictional braking force after the electromagnetic interaction causes the elevator car to move below a selected threshold speed.