WO2004033354A1

WO2004033354A1 - Elevator safety device

Info

Publication number: WO2004033354A1
Application number: PCT/US2002/032249
Authority: WO
Inventors: Luis Marti; Fernando Santos
Original assignee: Otis Elevator Company
Priority date: 2002-10-09
Filing date: 2002-10-09
Publication date: 2004-04-22
Also published as: AU2002343491A1

Abstract

An elevator system (20) includes a safety device (30) for controlling movement of an elevator car (22) as needed. The inventive safety device (30) includes movable members (34) that support rollers (44) for selectively moving the rollers (44) into engagement with corresponding surfaces (48) on guide rails (24). Brake pads (50) apply a braking force to side surfaces (52) of the rollers (44). The braking force in the inventive arrangement is applied in a direction generally parallel to an axis of rotation of the rollers and is not applied directly to the guide rail surfaces.

Description

ELEVATOR SAFETY DEVICE

Technical Field

This invention generally relates to safety devices for elevator systems. More particularly, this invention relates to an elevator safety device having rollers that engage a guide rail as needed where a braking force is applied to the rollers and not directly to the guide rail.

Description of the Prior Art

Elevator systems typically include a car that moves along guide rails within a hoistway between different levels in a building. A variety of arrangements are known for causing the desired movement of the elevator car. Conventional systems also include safety devices for stopping the car from moving in the event that the normal drive system does not operate as required. A variety of governors or safety brakes are known. There are several shortcomings and drawbacks associated with conventional arrangements. One major issue is that the conventional arrangements depend upon friction against the guide rail. One concern associated with such arrangements is that lubricant, moisture, contaminants, rust, etc. can adversely impact the performance of the safety system when the guide rail surface is not conducive to the desired amount of friction. Further, use of such safety devices typically changes or damages the guide rail surface. The same guide rail surface is typically used for rollers that guide the car during elevator system operation, and, therefore, any changes to the guide rail surface tends to introduce noise or vibration during subsequent car movement, which reduces elevator ride quality. Another significant drawback associated with conventional arrangements is that common friction materials, such as those used for automotive brake pads, typically cannot be used in elevator safety systems. The extreme working conditions required and the high amount of friction energy dissipated between the friction material and the guide rail typically requires the use of metallic alloys. These materials introduce additional cost and complexity into elevator system safety devices. Another drawback associated with some conventional arrangements is that a spring typically moves the braking elements into engagement with the guide rail surface. The compression stroke necessary to achieve the desired braking force typically requires a relatively large spring, which introduces additional mass and material cost. It is desirable to be able to reduce costs and to minimize the size of elevator system components to conserve hoistway space, for example.

This invention provides a unique safety device arrangement that avoids the shortcomings and drawbacks of the prior art.

SUMMARY OF THE INVENTION

In general terms, this invention is a safety device for use in an elevator system that utilizes a braking force that is not applied directly to the elevator system guide rails. Instead, braking members engage the guide rails and a braking force is applied directly to the engaging members so that more reliable interaction between the braking members and the guide rail is achieved.

One example device designed according to this invention includes a base member that is adapted to be supported for movement with an elevator car. A movable member is supported on the base member to be selectively movable relative to the base member. A roller is supported on the movable member such that the roller is rotatable relative to the movable member. The roller has a rail engaging surface that is adapted to engage one surface on a rail in the elevator system when the movable member moves into a rail engaging position. The roller has side surfaces between the rail engaging surface and a center of the rail. A brake that is supported by the movable member engages at least one of the side surfaces of the roller to apply a braking force against the side surface of the roller to resist rotation of the roller and thereby cause the elevator car to stop.

In one example arrangement, the movable member comprises a lever having two arms between which the rail is received. A plurality of brake pads are supported on the lever arms so that the brake pads engage side surfaces of the roller to resist rotation of the roller. A variety of brake pad materials may be used in a device designed according to this invention. In one example, the roller has a guide rail engaging surface that is a knurled, hardened metal. The knurled surface provides sufficient engagement between the roller and guide rail without causing deformation of the guide rail surface.

The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 schematically illustrates selected components of an elevator system incorporating a safety device designed according to this invention.

Figure 2 schematically illustrates an example safety device designed according to this invention in a first position.

Figure 3 is a partial cross sectional view of the embodiment of Figure 2 taken along the lines 3-3 in Figure 2.

Figure 4 shows the example embodiment of Figure 2 in a second operating position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Selected portions of an elevator system 20 are schematically shown in

Figure 1. An elevator car 22 moves along guide rails 24 in a hoistway between different levels within a building, for example. Conventional components are used to cause the desired movement of the elevator car 22 within the hoistway.

The inventive system includes a safety device 30 that is selectively used to stop movement of the car 22 in the event of a failure in the normal drive or braking system, for example. The illustrated example in Figure 1 shows the safety device 30 supported directly on a portion of the elevator car 22. The invention is not so limited and the safety device 30 may be mounted on one or more brackets associated with the car as will be appreciated by those skilled in the art. The safety device 30 is supported for movement with the elevator car 22 so that the safety device 30 is capable of selectively engaging the guide rails 24 as needed. As best appreciated from Figures 2 and 3, the safety device 30 includes a base member 32 that is adapted to be supported such that the safety device 30 moves with the elevator car 22. Movable members 34 are supported by the base 32 such that the movable members are movable relative to the base as needed. In the illustrated example, mounting members 36 provide pivot axes about which the movable members 34 are movable as shown by the arrows 38. Figure 2 illustrates the safety device 30 in a first operating condition where the safety device does not engage the guide rails 24. In this position, support members 39 keep the moveable members 34 in a desired ready position. As best seen in Figure 3, the example movable members 34 comprise levers that include two arms 40 and 42.

Rollers 44 are supported by the movable members 34 so that the rollers 44 are rotatable relative to the movable members. Each roller includes a guide rail engaging surface 46 that is adapted to selectively engage a corresponding surface 48 on an associated guide rail 24. In the illustrated example, the guide rail engaging surface 46 comprises a knurled, hardened metal. A variety of surface treatments or surface characteristics may be used in safety devices designed according to this invention. A knurled surface is used in the illustrated example to provide the desired amount of frictional engagement between the knurled engaging surface 46 and the corresponding guide rail surface 48. The knurled surface is preferred in the illustrated example because it provides the desired amount of friction without introducing an undesirably high likelihood for damaging or deforming the surface 48 on the guide rail 24.

The base 32, moveable members 34, the rollers 44 and the other components of the safety device may comprise various materials that are able to withstand the forces associated with stopping the car 22 from moving. Those skilled in the art who have the benefit of this description will be able to select appropriate materials.

The inventive device includes applying a braking force to the rollers 44 instead of applying a braking force directly to the guide rails. As best appreciated from Figure 3, a plurality of brake pads 50 are positioned to engage side surfaces 52 on the rollers 44. In one example, the side surfaces 52 have a generally planar contour extending between the rail engaging surface 46 and an opening through the center of the roller. The inventive arrangement provides a significant advantage in that the braking force is applied to the side surfaces of the rollers to resist rotation of the rollers. With such an arrangement, the energy dissipation occurs between the brake pads and the rollers and not between the rollers and the guide rail. This greatly reduces the likelihood of causing distortion or damage to the surface of the guide rails, which enhances the quality of elevator system performance over the life of the system.

Another significant advantage to the inventive arrangement is that a variety of brake pad materials may be used. In one example, conventional brake pad materials, such as those used in automotive braking applications, is used for the brake pads 50. Those skilled in the art who have the benefit of this description will be able to select an appropriate braking material from among commercially available materials.

In the illustrated example, the rollers 44 are rotatable about support members 56 associated with the movable members 34. The braking force in the illustrated example is applied to the rollers 44 in a direction that is parallel to the axis of rotation 54.

The movable members 34 are movable from a non-engaging position as shown in Figure 2, to a roller engaging position as shown in Figure 4. In this position, the rail engaging surfaces 46 on the rollers 44 engage the corresponding surfaces 48 on the guide rails 24. The brake pads 50 resist rotation of the rollers and, therefore, the safety device 30 operates to stop movement of the elevator car 22 relative to the guide rails 24.

Another advantage of this invention is that it reduces the size of a safety device. The inventive arrangement does not rely upon large moving springs to achieve a compressive braking force and, therefore, space savings are achieved. In one example, the arms 40 and 42 are secured in place by securing members

58 and 60 so that the brake pads 50 are in the desired amount of engagement with the side surfaces 52 on the rollers 44. In the example of Figure 3, the support members 56 comprise a bolt having a head 58 with an opposite end 60 secured to the arm 42. A Belleville washer 62 serves as a biasing member to bias the arms 42 and 40 together so that the desired engagement between the brake pads 50 and the side surfaces 52 of the rollers 34 is maintained during the expected lifetime of the safety device 30. The biasing member 62 of this invention differs from the moving springs used in conventional arrangements in that it is far more compact and does not require a lengthy compression stroke to achieve the desired effect. A variety of elastic or compressive materials may be used for the biasing member 62. The illustrated example includes a Belleville washer. As the brake pads 50 wear, the biasing member 62 tends to urge the arms 40 and 42 together, which continues to urge the brake pads 50 into engagement with the side surfaces 52 of the roller 44.

Moving the movable members 36 from the position illustrated in Figure 2 to the position illustrated in Figure 4 can be accomplished in a variety of ways. In the illustrated example, a governor rope 66 is associated with a linkage 68 that is connected to the movable members 36 for causing the desired movement into a guide rail engaging position as needed. The illustrated example includes link members 70 and 72 that facilitate symmetric activation of the device 30 by the governor rope 66. Known techniques for engaging or operating a safety device using a governor rope are applicable to the inventive arrangement. The illustrated example includes stop members 78 associated with the base member 32 to prevent the movable members 34 from moving beyond the position illustrated in Figure 4 where the rollers 44 engage the guide rail as needed to stop the elevator car from moving.

In another example, one of the rollers 44 is replaced with a non-rolling braking member that engages one surface 48 on a guide rail and a roller 44 engages the oppositely facing surface 48. A variety of other modifications to a device designed according to this invention may become apparent to those skilled in the art based upon this description.

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

CLAIMSWe claim:

1. A safety braking device (36) for use in an elevator system (20), comprising: a base member (32) adapted to be supported for movement with an elevator car (22); a moveable member (34) supported on the base member to be selectively moveable relative to the base member; a roller (44) supported on the moveable member such that the roller is rotatable relative to the moveable member, the roller having a rail engaging surface

(46) that is adapted to engage one surface (48) on a rail (24) in the elevator system when the moveable member moves into a rail engaging position, the roller having side surfaces (52) between the rail engaging surface and a center of the roller; and a brake (50) supported by the moveable member and engaging at least one of the roller side surfaces to apply a braking force against the side surface to resist rotation of the roller.

2. The device of claim 1, including a brake pad (50) rigidly supported on the moveable member on each side of the roller such that the brake engages two side surfaces (52) on the roller (44).

3. The device of claim 1, wherein the moveable member (34) comprises a lever that is pivotally supported to pivot relative to the base member from a first position where the roller (44) does not engage a rail surface (48) to a second position where the roller (44) engages the rail surface (48).

4. The device of claim 1, including a stop (78) supported on the base member (32) to prevent the moveable member (34) from moving beyond a selected position where the roller engages the rail surface.

5. The device of claim 1, including a biasing member (62) that biases the brake toward the roller side surface.

6. The device of claim 1, wherein the moveable member (34) comprises two arms (40, 42), the roller (44) is received between the arms (40, 42) and the brake (50) is supported between at least one of the arms and the roller.

7. The device of claim 6, including a biasing member (62) that biases the arms toward each other and biases the brake toward the roller side surface.

8. The device of claim 1, including a second moveable member (34) supported on the base member (32), a second roller (44) supported by the second moveable member (34) and a brake (50) associated with the second roller and wherein the moveable members are positioned on the base member such that the rollers are adapted to engage oppositely facing surfaces (48) on a rail (24) when the moveable members move into an engaging position.

9. The device of claim 1, wherein the roller rail engaging surface (46) comprises a hardened, knurled metal.

10. The device of claim 1, wherein the braking force is applied perpendicular to the rail engaging surface (46).

11. An elevator system (20), comprising: a car (22); a guide rail (24) that guides movement of the car; a moveable member (34) supported for movement with the car (22), the moveable member being moveable between first and second positions; a roller (44) supported on the moveable member, an outer surface (46) on the roller engaging a selected surface (48) on the guide rail (24) when the moveable member moves into the second position; and a brake (50) that engages a side surface (52) on the roller (44) to apply a braking force to resist rotation of the roller and movement of the cab relative to the guide rail when the roller engages the rail.

12. The system of claim 11, including a brake pad (50) on oppositely facing side surfaces (52) of the roller (44) that apply a braking force in a direction that is parallel to an axis of rotation of the roller.

13. The system of claim 11, including a stop member (78) that prevents the moveable member from moving beyond the second position.

14. The system of claim 11, including a second moveable member (34) supported for movement with the car (22), a second roller (44) supported by the second moveable member and a brake associated with the second roller and wherein the moveable members are positioned on opposite sides of the rail such that the rollers engage oppositely facing surfaces on the rail when the moveable members move into the second position.

15. The system of claim 11, including a biasing member (62) that biases the brake into the roller side surface.

16. The system of claim 11, wherein the moveable member (34) comprises two arms (40, 42), the roller (44) is received between the arms and the brake (50) is supported between at least one of the arms and the roller.

17. The device of claim 16, including a biasing member (62) that biases the arms (40, 42) toward each other and biases the brake (50) toward the roller side surface (52).