ELEVATOR SYSTEM WITH MULTIPLE CARS IN A HOISTWAY

1. Field of the Invention This invention generally relates to elevator systems. More particularly, this invention relates to an elevator system having more than one car in a hoistway.

2. Description of the Related Art

Many elevator systems include a car and counterweight coupled together by a rope or other load bearing member. A machine controls movement of the car to service passengers between various levels in a building, for example. As known, the counterweight and car typically move in opposite directions within a hoistway.

It has been proposed to include multiple elevator cars within a single hoistway. Such an arrangement provides advantages for increased or improved passenger service, for example. Example patents pertaining to elevator systems having multiple cars within a hoistway include U.S. Patent Nos. 1,837,643; 1,896,776; 5,419,414; 5,584,364; and the published application U.S. 2003/0075388. Each of these shows a different arrangement of components within such an elevator system.

There are various challenges presented when trying to provide multiple cars in a hoistway. For example, it is necessary to control movement of the system components to avoid collisions between the elevator cars. It is also a challenge to arrange the counterweights and the load bearing members extending between the counterweights and the cars in a manner that efficiently uses hoistway space and does not require special modifications or undesirably large amounts of additional space. This invention provides several techniques for arranging elevator system components to accommodate multiple cars in a hoistway.

SUMMARY OF THE INVENTION

One example elevator system designed according to this invention includes a first elevator car and a first counterweight in a hoistway. A first load bearing member has a first length and couples the first elevator car to the first counterweight. A second elevator car is in the hoistway below the first elevator car. A second

counterweight is in the hoistway above the first counterweight. A second load bearing member has a second length and couples the second elevator car to the second counterweight. The lengths of the load bearing members (i.e., the first and second lengths) permit contact between the first and second counterweights but prevent contact between the first and second elevator cars.

By strategically selecting the lengths of the load bearing members and considering a counterweight buffer stroke plus an expected dynamic jump of the elevator cars, it is possible to avoid contact between elevator cars by always maintaining a spacing between them. In some examples, the dimensions of the counterweights and buffers associated with the counterweights are also selected to control the spacing between the elevator cars.

Another example elevator system includes a first elevator car, a first counterweight, a second elevator car and a second counterweight. The second elevator car is below the first elevator car. The second counterweight is above the first counterweight. Load bearing members coupling the respective elevator cars and counterweights have associated roping ratios that are different.

In one example, the first load bearing member that associates the first elevator car and first counterweight has an associated roping ratio of 1: 1. The second load bearing member has an associated roping ratio of 2:1. In another example elevator system designed according to this invention, the elevator car positioned above other elevator cars has at least one passage within an envelope of the cab portion through which at least a portion of the load bearing member associated with a lower elevator car passes.

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.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 schematically illustrates selected components of an elevator system having more than one elevator car in a hoistway.

Figures 2A and 2B schematically illustrate one example elevator system configuration.

Figures 3A and 3B schematically illustrate two roping strategy examples. Figures 4A and 4B schematically illustrate another example elevator system configuration.

Figures 5A and 5B schematically illustrate another elevator system configuration.

Figures 6A and 6B schematically illustrate another example elevator system configuration.

Figures 7A-7C schematically illustrate another example elevator system configuration. Figures 8A-8C schematically illustrate another example elevator system configuration.

Figures 9A-9C schematically illustrate another example elevator system configuration.

Figures lOA-lOC schematically illustrate another example elevator system configuration.

Figures 1 IA-11C schematically illustrate an elevator cab feature used in conjunction with one example roping strategy.

Figure 12 schematically shows somewhat more detail of one example arrangement consistent with the embodiment of Figures 1 IA-11C.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figure 1 schematically shows selected portions of an elevator system 20. A first elevator car 22 is coupled with a first counterweight 24 for movement within a hoistway 26. Although not shown in Figure 1, the first elevator car 22 is coupled to the first counterweight 24 by a plurality of ropes or belts as known. For purposes of this description, "a load bearing member" should be understood to mean one or more ropes or belts. A second elevator car 32 is positioned below (according to the drawing) the first elevator car 22. The second elevator car 32 is associated with a second counterweight 34 by a load bearing member (not shown) so that both move within the hoistway 26 as known.

In this example, the counterweights 24 and 34 travel along common guiderails 36. In other words, the counterweights 24 and 34 share the same guiderails.

Another feature of the system 20 schematically shown in Figure 1 is that at least one buffer 38 is supported on at least one of the counterweights 24 and 34 to absorb impact associated with the counterweights contacting each other. The buffer

38 in one example is partially supported within the envelope of the counterweight. A set of relatively smaller bumpers 39 are provided on at least one of the cars 22, 32.

Various features of such an elevator system are described in connection with the various example embodiments described below. For example, load bearing members, such as ropes or belts couple the elevator cars and counterweights, respectively. One feature of one example system designed according to this invention includes selecting lengths of the load bearing members and considering a buffer stroke of the counterweight buffer 38 and an expected dynamic jump of the elevator cars 22 and 32 to allow contact between the counterweights or associated buffers within the hoistway and to prevent contact between the elevator cars. The resulting difference in car and counterweight separation distances is greater than the counterweight buffer stroke plus the expected dynamic jump of the elevator cars. Given this description, those skilled in the art will realize how car speeds, buffer strokes, component sizes, etc., will combine to meet their particular needs. In some examples, the lengths of the load bearing members and their association with the elevator system components ensure that the elevator cars will never contact each other under normal system operating conditions. Such an arrangement also provides, for example, for adequate overhead clearance above a car that is positioned beneath another car for maintenance or inspection procedures.

In the event that counterweight jump or overspeed conditions result in contact between the cars 22 and 32, the buffers 39 absorb some of the energy associated with such an impact.

Another feature of an example elevator system designed according to this invention is that a first roping ratio for one elevator car and counterweight is different than a second roping ratio for the other elevator car and counterweight. Depending on the selection of roping ratios, different features may be incorporated into an elevator system designed according to this invention. Such features will be described in connection with corresponding examples to be discussed below.

In some example systems designed according to this invention, the roping placement strategy includes allowing for some of the load bearing members to pass through a passage associated with at least an upper elevator car. Such passages allow for using various roping ratios, for example, while still maintaining space limitations on a hoistway.

A variety of combinations of such features may be used depending on the needs of a particular situation. Given this description, those skilled in the art will be able to determine how best to combine the disclosed features to meet the needs of their particular situation. Figures 2A and 2B schematically show one example elevator system configuration. In this example, the first elevator car 22 is coupled to the first counterweight 24 by a load bearing member 40. A drive sheave or traction sheave 42 causes movement of the load bearing member 40 to cause the desired movement of the elevator car 22 in a known manner. Deflector sheaves 44 and 46 are included in the illustration to show how the load bearing member 40 is routed within the hoistway to accommodate both elevator cars and to achieve a desired angle of wrap around the drive sheave 42.

The second elevator car 32 is coupled to the second counterweight 34 by a load bearing member 50. A separate drive sheave 52 and deflector sheaves 54 are included for routing the second load bearing member 50.

As can be appreciated from Figure 2A, both of the load bearing members 40 and 50 have an associated roping ratio that is 1:1. In this example, the length of the first load bearing member 40 is selected based upon the combined length of the second load bearing member 50 and the second counterweight 34 so that the counterweights 24 and 34 will contact each other before the elevator cars 22 and 32 are able to contact each other. In other words, the length of the first load bearing member 40 is selected to prevent contact between the elevator cars 22 and 32. In one example, the length of the load bearing member 40 will be less than a combined length of the second load bearing member 50 and a distance between a bottom of the counterweight 34 and a termination of the load bearing member 50 associated with the counterweight 34. Where a buffer 38 is included between the counterweights, the

size or stroke length of the buffer is also considered when selecting the length of the load bearing member 40.

Figure 2A shows this example arrangement from the side while Figure 2B shows the arrangement from the front (focusing only on the elevator cars 22 and 32). The counterweights 34 and 24 are behind the cars 22 in this example.

The second load bearing member 50 is effectively "split" and some belts or ropes are provided on one side of the car 32 while other belts or ropes are provided on another side of the car 32. In the example of Figure 2B, the load bearing members 50 are on the outside of the elevator car 22. Figures 3A and 3B schematically show two strategies for routing load bearing members where some of them are one side of an elevator car and others are on an opposite side. In the example of Figure 3A, a single drive machine 60 is associated with drive sheaves 52 to cause desired movement of the load bearing member 50 and the elevator car 32. In the example of Figure 3B, independent drive machines (not illustrated) operate drive sheaves 52 to cause desired car movement.

Figures 4A and 4B show another example elevator system where the load bearing members 40 and 50 each have an associated roping ratio of 1:1. In this example, the counterweights 24 and 34 are positioned along the side of the elevator cars 22 and 32. The illustration of Figure 4A is a front view while the illustration of Figure 4B is a side view (showing only the cars and portions of the load bearing members). In this example, the deflector sheaves 54 and 56 are only used for some of the second load bearing member belts or ropes 50 (i.e., those extending from the right side of the car 32 according to the drawing). This allows for routing the load bearing members around the elevator car 22 to achieve the side-positioned counterweight arrangement.

Figures 5A and 5B schematically show another elevator system configuration where the load bearing members 40 and 50 each have an associated roping ratio of 2:1. Figure 5A is a side view while Figure 5B is a front view. The counterweights 24 and 34 are located behind the cars 22 and 32 in this example. One feature of an arrangement where the first load bearing member 40 has a

2: 1 roping ratio is that it is possible to have the load bearing member 40 outside of oppositely facing surfaces on the second counterweight 34. In this example, a

deflector sheave 62 travels with the second counterweight 34 through the hoistway. Another deflector sheave 64 travels with the first counterweight 24. In this example, a diameter of the deflector sheave 64 is selected to be larger than an outside dimension of the second counterweight 34 such that the load bearing member 40 is guided outside of the oppositely facing surfaces (i.e., the right and left sides of the counterweight 34 in Figure 5A). Such an arrangement is possible whenever the first load bearing member 40 coupling the first elevator car 22 to the first counterweight 24 has associated roping ratio of 2:1. Such an arrangement is possible regardless of whether the second load bearing member 50 has an associated roping ratio of 2:1. Another feature of the example in Figures 5A and 5B is that deflector sheaves

66 that travel with the second elevator car 32 are positioned relative to the car so that the load bearing member 50 is entirely on one side of a car guiderail 68. In this example, the car guiderail 68 is aligned offset from the center of gravity of the elevator cars 22 and 32. It may not be possible to center the car guiderail 68 in such an arrangement. Both of the sets of ropes or belts of the load bearing member 50 are behind the rail 68 in the illustration. The example of Figure 2A, by contrast, may have one of the sides of the load bearing member 50 (i.e., the rope or belt associated with one side of the car 32) positioned on one side of the car guiderail with the others (i.e., those associated with an opposite side of the car 32) positioned on an opposite side of the car guiderail. Such a roping arrangement makes it easier to have the car guiderail centered relative to the center of gravity of the elevator cars.

Figures 6A and 6B schematically illustrate another elevator system configuration where both load bearing members 40 and 50 have an associated 2:1 roping ratio. In this example, the counterweights 34 and 24 are supported on the side of the cars 22 and 32.

Whenever at least one of the load bearing members has a 2: 1 roping ratio, it is possible to position the drive sheaves, drive machines or both at the same vertical position or height in a hoistway or machine room.

Figures 7A-7C schematically show another example elevator system configuration. In this example, the load bearing member 50 associated with the second elevator car 32 and the second counterweight 34 has an associated roping ratio that is 1: 1. The first load bearing member 40 has a roping ratio of 2:1. In this

example, the roping ratios of the load bearing members are different. It can be appreciated from Figure 7 A, for example, that the use of a sufficiently large deflector sheave 64 associated with the counterweight 24 allows for the load bearing member 40 to be on the outside of oppositely facing outside surfaces of the second counterweight 34. In this example, some of the ropes or belts for the load bearing member 50 travel about deflector sheaves 54 and 56 while others do not. This allows for routing the belts or ropes around the outside of the first elevator car 22. The counterweights 34 and 24 are on the side of the elevator cars 22 and 34.

Figures 8A-8C schematically illustrate another example elevator system configuration where the first load bearing member 40 has an associated roping ratio of

2:1 and the second load bearing member 50 has an associated roping ratio of 1:1. In the example of Figures 8A-8C, the counterweights 34 and 24 are located behind the elevator cars 22 and 32.

Figures 9A-9C schematically show another elevator system configuration. In this example, the first load bearing member 40 has an associated roping ratio of 1:1. The second load bearing member 50 has an associated roping ratio of 2:1.

Another feature of this example configuration is that the second counterweight

34 includes a passage 70, which comprises an opening through a central portion of the second counterweight 34 in this example. The passage 70 allows for the first loading bearing member 40 to pass through the second counterweight 34. Such an arrangement may provide space savings, for example.

In the examples of Figures 9A-9C, the counterweights 34 and 24 are located behind the elevator cars 22 and 32.

Another example arrangement where the first load bearing member 40 has a 1:1 roping ratio and the second load bearing member 50 has a 2:1 roping ratio is shown in Figures lOA-lOC. In this example, the second counterweight 34 and the first counterweight 24 are located on the side of the elevator cars 22 and 32. This example also includes a passage 70 through the second counterweight 34.

Configuring an elevator system as schematically shown in Figures lOA-lOC may be considered the most optimum solution for some situations because it requires the fewest number of sheaves near the top of the hoistway and it is possible to have the first load bearing member 40 pass through the passage 70 in the second

counterweight 34. Such an elevator system configuration may be preferred where space savings is a primary consideration, for example.

Figures 1 IA-11C schematically show another elevator system configuration. In this example, the first load bearing member 40 has an associated roping ratio of 1: 1. The second load bearing member 50 has an associated roping ratio of 2:1. The portion of the second load bearing member 50 belts or ropes that extend between the second elevator car 32 and a top of the hoistway 26 pass through passages 80 on the elevator car 22. In the illustrated example, the passages 80 have a dimension shown at 82 that is large enough for the belts or ropes of the second load bearing member 50 to be accommodated through the passage 80. In this example, the load bearing member 50 has an associated roping ratio of 2:1. Accordingly, whenever the first elevator car 22 is stationary, there is no relative movement between the load bearing member 50 within the passage 80 and the first elevator car 22 even when the second elevator car 32 is moving. Having passages 80 on an elevator car 22 allows for space savings within a hoistway because the ropes or belts of the load bearing member 50 need not be routed on the outside of the elevator car 22.

As can be appreciated from Figure HC, the passages 80 fit within an envelope of a passenger cab portion of the example first elevator car 22. Although not illustrated, the elevator cars include a frame and a cab portion supported on the frame in a known manner. The cab portion has an outside envelope and defines the space within which passengers are carried by the elevator system. In this example, the passages 80 preferably fit within the envelope of the elevator cab portion.

Figure 12 schematically shows one arrangement where the passages 80 are associated with a portion of the cab that normally accommodates an elevator car operating panel 90. In this example, at least one internal sidewall 92 of the elevator car supports the car operating panel 90, which includes a touch screen or buttons accessible by a passenger on one side of the sidewall 92. An opposite side of the sidewall 92 (i.e., an outwardly facing side relative to the interior of the cab) faces the interior of the passage 80. By accommodating the belts or ropes of the load bearing member 50 within a space adjacent to or associated with the space used to accommodate a car operating panel 90, space-savings within a hoistway can be

achieved without sacrificing a significant amount of additional capacity within the interior of the elevator car cab portion.

The various examples shown above illustrate elevator system configurations having strategically sized load bearing members, various combinations of roping ratios and various features for realizing optimum space usage, minimizing the number of components required or both. Given this description, those skilled in the art will be able to select what combination of features will work best for their particular situation.

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.