Patent Description:
For many years, roping in elevator systems included round steel ropes. More recently, flat belt technologies were developed that provided advantages over traditional, round steel rope arrangements. Even with the advancement, those skilled in the art have been striving to improve elevator load bearing member technology.

<CIT> (which forms prior art according to Art. <NUM>(<NUM>) EPC) and <CIT> disclose tension elements of an elevator system comprising first and second fibers.

In a first aspect, a load bearing member including a unidirectional weave is provided as claimed in claim <NUM>.

In an example embodiment having at least the features of the elevator load bearing member of the previous paragraph, the first material comprises a first type of polymer, the second material comprises a second type of polymer, at least some of the load bearing fibers comprise the first type of polymer and at least some others of the load bearing fibers comprise the second type of polymer.

In an example embodiment having one or more features of the elevator load bearing member of any of the previous paragraphs, at least some of the load bearing fibers comprise the first material and the second material.

In an example embodiment having one or more features of the elevator load bearing member of any of the previous paragraphs, the coating comprises a j acket that defines a traction surface of the elevator load bearing member.

In an example embodiment having one or more features of the elevator load bearing member of any of the previous paragraphs, the jacket comprises a thermoplastic material and the coating comprises an adhesive between the thermoplastic material and at least some of the load bearing fibers.

In an example embodiment having one or more features of the elevator load bearing member of any of the previous paragraphs, a ratio of the first material to the second material is <NUM>:<NUM>.

In an example embodiment having one or more features of the elevator load bearing member of any of the previous paragraphs, the first material comprises at least one of carbon, liquid crystal polymer, aramid, polyhydroquinone-diimidazopyridine, polybenzimidazole, polypyridobisimidazole and polybenzoxazole.

In a second aspect, a method of making an elevator load bearing member including a unidirectional weaving is provided as claimed in claim <NUM>.

In an example embodiment having at least the features of the method of the previous paragraph, the first material comprises a first type of polymer, the second material comprises a second type of polymer, at least some of the load bearing fibers comprise the first type of polymer, and at least some others of the load bearing fibers comprise the second type of polymer.

In an example embodiment having one or more features of the method of any of the previous paragraphs, at least some of the load bearing fibers comprise the first material and the second material.

In an example embodiment having one or more features of the method of any of the previous paragraphs, the coating comprises applying a jacket onto the load bearing fibers and the jacket defines a traction surface of the elevator load bearing member.

In an example embodiment having one or more features of the method of any of the previous paragraphs, the jacket comprises a thermoplastic material and the coating comprises applying an adhesive onto the load bearing fibers between the thermoplastic material and at least some of the load bearing fibers.

In an example embodiment having one or more features of the method of any of the previous paragraphs, the bonding comprises heating and applying pressure to the load bearing fibers.

In an example embodiment having one or more features of the method of any of the previous paragraphs, the heating includes exposing the load bearing fibers to a temperature that is at least as high as the melting point of the second material and below the melting point of the first material.

In an example embodiment having one or more features of the method of any of the previous paragraphs, the bonding comprises pressing the load bearing fibers between first rollers that are heated and pressing the load bearing fibers between second rollers that are not heated.

In an example embodiment having one or more features of the method of any of the previous paragraphs, a ratio of the first material to the second material is between <NUM>: <NUM> and <NUM>: <NUM>.

In an example embodiment having one or more features of the method of any of the previous paragraphs, the ratio is <NUM>: <NUM>.

In an example embodiment having one or more features of the method of any of the previous paragraphs, the first material comprises at least one of carbon, liquid crystal polymer, aramid, polyhydroquinone-diimidazopyridine, polybenzimidazole, polypyridobisimidazole and polybenzoxazole.

<FIG> schematically shows selected portions of an elevator system <NUM> including an elevator car <NUM> and counterweight <NUM>. A traction sheave <NUM> associated with a machine (not specifically illustrated) selectively controls movement of a load bearing member <NUM>, which suspends the elevator car <NUM> and counterweight <NUM>, to control the movement or position of the elevator car <NUM>. For illustration purposes, a single load bearing member <NUM> is represented in <FIG>. Multiple load bearing members would be included in many embodiments.

<FIG> schematically illustrates an example load bearing member <NUM>. A plurality of load bearing fibers <NUM> serve as the primary load bearing components of the load bearing member <NUM>. The load bearing fibers <NUM> are woven into a unidirectional weave. The load bearing fibers <NUM> are arranged as warp fibers extending in a length direction L of the load bearing member <NUM>. In a non-claimed embodiment, a unidirectional weave has fibers extending in a single direction and does not include weft fibers that would be parallel to a width direction W of the load bearing member.

In the claimed embodiments, the unidirectional weave includes some weft fibers transverse to the single direction of the warp fibers but such weft fibers are far fewer in number than the warp fibers and are not considered significant to the load bearing performance of the unidirectional weave. Any such weft fibers may serve a limited purpose during manufacturing, for example.

Weaving the load bearing fibers into a unidirectional weave avoids any braiding of the fibers and, therefore, provides improved strength characteristics compared to other types of weaves. A unidirectional weave of load bearing fibers <NUM> also provides improved flexibility characteristics.

In the embodiment shown in <FIG>, the load bearing fibers <NUM> are arranged or grouped as cords <NUM> and the cords <NUM> are woven into the unidirectional weave. In the embodiment shown in <FIG>, the load bearing fibers <NUM> are individually woven into the unidirectional weave, which effectively forms a layer or sheet <NUM>.

The load bearing fibers <NUM> include at least two different types of material. Some embodiments include at least one polymer and another type of material such as carbon or another organic material. One of the materials is selected to at least partially melt for bonding the load bearing fibers <NUM> together. The material that provides the bonding has properties including a melting point that allows for at least partially melting that material without compromising the mechanical properties of another material that at least some of the other load bearing fibers <NUM> are made.

For discussion purposes, the illustrated example embodiment includes a first type of polymer material and a second type of polymer material that have different melting points. The first type of polymer material has a higher melting point than the melting point of the second type of polymer material. Including different types of polymer with different melting points allows for bonding the load bearing fibers <NUM> of the unidirectional weave together in a way that preserves the mechanical properties of the fibers made of the first type of polymer and maintains the configuration of the unidirectional weave. For example, the plurality of load bearing fibers <NUM> are bonded together by at least some of the second type of polymer that is at least partially melted without melting any of the first type of polymer material.

In some embodiments each of the load bearing fibers <NUM> comprises only one type of polymer. For example, some of the fibers <NUM> are made of the first type of polymer while others are made of the second type of polymer. In other embodiments at least some of the fibers <NUM> include more than one material and may include multiple polymers or at least one type of polymer and another type of material.

The unidirectional weave of fibers <NUM> includes a ratio of the first type of polymer to the second type of polymer (e.g., higher melting point polymer to lower melting point polymer) in a range from <NUM>:<NUM> to <NUM>:<NUM>. Some embodiments include a ratio of the first type of polymer to the second type of polymer of <NUM>:<NUM>. An example embodiment includes a ratio of <NUM>: <NUM>. In preparation of the multi-polymer composite, the ratio of high melt point fibers to low melting point fibers depends on the processing and linear density of the fibers.

The unidirectional woven fibers are consolidated under a selected pressure at the specific temperature that the second or low melting point polymer material melts and forms a hot fluid that adheres the higher melting point fibers together. On cooling from the consolidated high temperature, the low melting point polymer fibers recrystallize, which forms a resin matrix in composite. The original mechanical properties of the low melting point polymer fibers will change because they are at least partially melted. Including the higher melting point material allows for preserving the mechanical properties of the higher melting point fibers. The final property of the composite provides the necessary characteristics for elevator system operation when there are enough higher melting point fibers, such as having more higher melting point fibers than lower melting point polymer fibers.

In an alternative embodiment of the preceding paragraph, the higher melting point fibers are replaced with fibers which cannot be melted and have a decomposition temperature, the decomposition temperature being higher than the melting point of the second polymer material.

Example higher melting point, or if the first material cannot be melted, example higher decomposition temperature, and high strength polymers include liquid crystal polymer, aramid, polyhydroquinone-diimidazopyridine, polybenzimidazole, polypyridobisimidazole and polybenzoxazole. The lower melting point and high strength polymers comprise at least one of ultrahigh molecular weight polyethylene and ultrahigh molecular weight polypropylene.

A jacket <NUM> covers the load bearing fibers in each of the illustrated example embodiments. The jacket <NUM> comprises a material that is suitable for establishing the desired traction with the traction sheave <NUM> to achieve the desired traction for controlling movement of the elevator car <NUM>. Example materials that are useful include compressible materials, such as a thermoplastic material or an elastomer. In some embodiments the jacket <NUM> comprises a thermoplastic polyurethane material.

<FIG> schematically illustrates an example method of making the disclosed load bearing member embodiments. The plurality of polymer load bearing fibers <NUM> are introduced or fed into unidirectional weaving equipment <NUM> where the fibers <NUM> are woven into the unidirectional weave. Then the woven fibers <NUM> are heated and pressed together by bonding equipment <NUM>. For example, the bonding equipment <NUM> includes heating elements that subject the woven fibers <NUM> to a temperature that is at least as high as the melting point of the second type of polymer and less than the melting point of the first type of polymer. Such heating at least partially melts at least some of the second type of polymer without melting any of the first type of polymer. Any fibers composed of only the first type of polymer are not melted or altered during such heating.

In the illustrated example arrangement the unidirectionally woven fibers <NUM> are fed through and pressed between heated rollers <NUM>. At least the rollers <NUM> heat the woven fibers <NUM> to a temperature sufficient to at least partially melt at least some of the second type of polymer. That melted polymer bonds the woven fibers <NUM> together.

In <FIG>, the bonding equipment <NUM> includes cooling rollers <NUM> to facilitate shaping or maintaining the shape of the unidirectional weave of fibers <NUM> while any melted polymer recrystallizes.

Once the unidirectional weave is at a suitable temperature it is coated by coating equipment <NUM>. In the illustrated example arrangement, the coating equipment <NUM> includes an adhesive applicator <NUM> that applies an adhesive coating onto the polymer load bearing fibers <NUM>. A jacket application device <NUM>, such as an extruder, applies the material of the jacket <NUM>.

A load bearing member including a multi-polymer unidirectional weave of load bearing fibers as disclosed above provides improved strength characteristics compared to traditional elevator roping or belts that rely on steel wires as the primary load bearing components. Additionally, load bearing members consistent with the example embodiments of this disclosure are lighter weight and provide cost savings compared to previous configurations.

Claim 1:
An elevator load bearing member (<NUM>), comprising:
a unidirectional weave of a plurality of load bearing fibers (<NUM>) including at least a first material and a second material, and a coating over the plurality of load bearing fibers (<NUM>);
wherein a melting point of the first material is higher than a melting point of the second material, or, where the first material is a material that cannot be melted and has a decomposition temperature, the decomposition temperature of the first material is higher than the melting point of the second material;
wherein the plurality of load bearing fibers (<NUM>) are bonded together by at least some of the second material that is at least partially melted; and
wherein, in said unidirectional weave, the load bearing fibers (<NUM>) are arranged as warp fibers extending in a length direction of the load bearing member (<NUM>) and some weft fibers transverse to the single direction of the warp fibers, but such weft fibers are far fewer in number than the warp fibers and are not considered significant to the load bearing performance of the unidirectional weave;
characterized in that the second material comprises at least one of ultrahigh molecular weight polyethylene and ultrahigh molecular weight polypropylene.