Patent Description:
Commercial elevator systems may use belt sheaves as part of a driving system to operate an elevator car. Belt-driven escalator systems have also been proposed. In passenger conveyor systems, drive sheaves are used to both drive and guide a belt. Deflector or idler sheaves may be located at various positions in the system (e.g. between the drive sheave and the elevator car, at the elevator car or at a counterweight) and may be used to maintain proper alignment, roping configuration and tension of belts during operation. Belt sheaves may have belt receiving grooves with a convex (i.e. "crowned") profile contour that restricts sideways wandering motion of belts to ensure alignment. Depending on the material of the sheave compared to the outer material of the belt, the belt groove may need to be machined and/or its surface treated in order to achieve a desired level of friction. Typically many belt sheaves are made of steel with the belt groove being roughened during production to fulfil friction requirements for a belt having a polymeric jacket. Manufacturing of belt sheaves, in particular idler sheaves, may be costly and require many processing steps.

<CIT> discloses a resin pulley. The resin composition includes <NUM> to <NUM> mass % of a phenolic resin as a base resin, <NUM> mass % or more of acrylonitrile butadiene rubber, <NUM> to <NUM> mass % of an inorganic fiber and <NUM> to <NUM> mas % of an inorganic powder. The resin further comprises a polyester acrylate.

<CIT> discloses a method of making a wheel assembly such as a pulley with a bearing. The wheel is molded from a material that shrinks when its temperature falls. The wheel has a circular opening at its center suitable for holding a circular bearing. A bearing is positioned inside the opening when the wheel is at a temperature above <NUM> degrees F. The wheel is cooled to room temperature and shrinks around the bearing, thereby fixing the bearing to the wheel.

<CIT> also discloses relevant prior art.

According to a first aspect of the present invention, there is provided a cylindrical sleeve for a sheave for a passenger conveyor system according to claim <NUM>. Disc gate injection moulding has been found to be a particularly beneficial technique for manufacturing a cylindrical sleeve for use as a sheave, i.e. including a groove arranged to receive a belt in a passenger conveyor system. This manufacturing technique is detectable in the cylindrical sleeve e.g. due to the absence of weld lines and/or the resultant fibre orientation, as will be described in more detail below.

The inventors have surprisingly found that manufacturing the cylindrical sleeve via disc gate injection moulding provides a cylindrical sleeve that is substantially free of weld lines and thus has an improved tensile strength (e.g. load-carrying capacity) and increased values of stress and strain at failure. Furthermore, the inventors have found that injection moulding a long (e.g. glass, e.g. carbon) fibre reinforced polymer using a disc gate mould injection process results in improved (e.g. glass, e.g. carbon) fibre orientation in a direction substantially parallel to the inner and outer surfaces of the cylindrical sleeve. The improved orientation has been found to further improve the tensile strength of the cylindrical sleeve, e.g. when compared to a component comprising randomly oriented (e.g. glass, e.g. carbon) fibres dispersed within a polymer matrix.

In particular, the inventors have surprisingly found that manufacturing the cylindrical sleeve by injection moulding through a disc gate provides a material structure that comprises a higher weight percent of the polymer matrix (and a lower weight percentage of (e.g. glass, e.g. carbon) fibre) present at the outer surface of the cylindrical sleeve. As such, disc gate moulding helps to provide a cylindrical sleeve with a smooth outer surface (e.g. low roughness) whilst reducing the requirement for additional machining, such as polishing or sanding. Providing a smooth surface is important because it helps to reduce damage to belts when the belts come into contact with the groove surface. Furthermore, the inventors have surprisingly found that the surface layers help to minimise the generation of electrostatic charges on the surface of the belt and/or sheave which may contribute to degradation or wear of the belt when present. This contrasts to sheaves made of steel which often require multiple post-production steps (e.g. machining steps such as polishing, e.g. coating steps to provide additional layers of material on the surfaces) in order to provide a surface which is suitable (e.g. sufficiently smooth with minimised charge generation) for use as a sheave for engagement with a belt in an elevator system.

In some examples the core comprises substantially all of the (e.g. glass, e.g. carbon) fibres present within the cylindrical sleeve, e.g. the core comprises substantially all of the between <NUM> wt. % to <NUM> wt. % (e.g. long) (e.g. glass, e.g. carbon) fibres dispersed within the polymeric material of the entire cylindrical sleeve. For example, the core may comprise between <NUM> wt. % to <NUM> wt. % (e.g. long) (e.g. glass, e.g. carbon) fibres, e.g. between <NUM> wt. % to <NUM> wt. % (e.g. long) (e.g. glass, e.g. carbon) fibres, e.g. between <NUM> wt. % to <NUM> wt. % (e.g. long) (e.g. glass, e.g. carbon) fibres dispersed within the polymeric material of the entire cylindrical sleeve. In some examples, the core comprises between <NUM> wt. % to <NUM> wt. % (e.g. long) (e.g. glass, e.g. carbon) fibres dispersed within the core polymeric matrix. For example, the core may comprise between <NUM> wt. % to <NUM> wt. % (e.g. long) (e.g. glass, e.g. carbon) fibres, e.g. between <NUM> wt. % to <NUM> wt. % (e.g. long) (e.g. glass, e.g. carbon) fibres, e.g. between <NUM> wt. % to <NUM> wt. % (e.g. long) (e.g. glass, e.g. carbon) fibres dispersed within the polymeric matrix of the core.

In some examples, the (e.g. two) surface layers comprise less than <NUM> wt. % (e.g. glass, e.g. carbon) fibre reinforcement, e.g. less than <NUM> wt. % (e.g. glass, e.g. carbon) fibre reinforcement, e.g. less than <NUM> wt. % (e.g. glass, e.g. carbon) fibre reinforcement, e.g. less than <NUM> wt. % (e.g. glass, e.g. carbon) fibre reinforcement, e.g. less than <NUM> wt. % (e.g. glass, e.g. carbon) fibre reinforcement, e.g. less than <NUM> wt. % (e.g. glass, e.g. carbon) fibre reinforcement, e.g. less than <NUM> wt. % (e.g. glass, e.g. carbon) fibre reinforcement.

In some examples, each surface layer has a thickness of less than <NUM>% the maximum thickness of the sheave, e.g. less than <NUM>%, e.g. less than <NUM>%, e.g. less than <NUM>%, e.g. less than <NUM>% the maximum thickness of the sheave. In some examples, each surface layer has a thickness of greater than <NUM>% the maximum thickness of the sheave, e.g. greater than <NUM>%, e.g. greater than <NUM>%, e.g. greater than <NUM>%, e.g. greater than <NUM>%, e.g. greater than <NUM>%, e.g. greater than <NUM>%, e.g. greater than <NUM>%, e.g. greater than <NUM>%, e.g. greater than <NUM>%, e.g. greater than <NUM>% the maximum thickness of the sheave.

In some examples, each surface layer has a thickness of less than <NUM>, e.g. less than <NUM>, e.g. less than <NUM>, e.g. less than <NUM>, e.g. less than <NUM>, e.g. less than <NUM>, e.g. less than <NUM>, e.g. less than <NUM>, e.g. less than <NUM>, e.g. less than <NUM>, e.g. less than <NUM>, e.g. less than <NUM>, e.g. less than <NUM>, e.g. less than <NUM>. In some examples, each surface layer has a thickness of greater than <NUM>, e.g. greater than <NUM>, e.g. greater than <NUM>, e.g. greater than <NUM>, e.g. greater than <NUM>, e.g. greater than <NUM>, e.g. greater than <NUM>, e.g. greater than <NUM>, e.g. greater than <NUM>, e.g. greater than <NUM>, e.g. greater than <NUM>, e.g. greater than <NUM>, e.g. greater than <NUM>.

In some examples, the core further comprises an outer portion, an inner portion and a central portion sandwiched between the outer and inner potions. The outer and inner portions include (e.g. glass, e.g. carbon) fibres that are predominantly aligned in parallel with the outer and inner surfaces of the cylindrical sleeve respectively. The central portion, sandwiched therebetween, includes (e.g. glass, e.g. carbon) fibres that are predominantly randomly orientated. In such examples, alignment of the (e.g. glass, e.g. carbon) fibres in parallel with the inner and outer surface helps to improve the mechanical properties, such as the tensile strength, of the cylindrical sleeve such that the sheave is able to withstand the high loads required for use within elevator systems whilst improving resistance to stress fractures or breakage.

For example, the cylindrical sleeve or its core comprises an outer portion wherein the (e.g. glass, e.g. carbon) fibre reinforcement is predominantly aligned with the outer surface, a central portion radially inward of the outer portion wherein the (e.g. glass, e.g. carbon) fibre reinforcement is predominantly arranged randomly, and an inner portion radially inward of the central portion wherein the (e.g. glass, e.g. carbon) fibre reinforcement is predominantly aligned with the inner surface.

In some examples, the surface layers are positioned to be radially outward of the outer portion and inner portion such that the surface layers form the outer surface and inner surface of the cylindrical sleeve.

In some examples, the cylindrical sleeve further comprises at least one annular rib extending from the inner surface towards the sheave axis. The annular rib(s) may divide the inner surface of the cylindrical sleeve into a first and second (e.g. axially spaced apart) portions. The annular rib may be formed as an artefact of a disc gate injection moulding process but then exploited to separate a pair of bearings held side-by-side within the cylindrical cavity.

In some examples, the sheave may comprise a first bearing held within the cylindrical cavity of the first portion and a second bearing held within the cylindrical cavity of the second portion.

In some examples, the annular rib has a width parallel to the sheave axis, wherein the width may be between <NUM> and <NUM>, e.g. between <NUM> and <NUM>, e.g. between <NUM> and <NUM>, e.g. between <NUM> and <NUM>, e.g. between <NUM> and <NUM>, e.g. approximately <NUM>.

The rolling elements, between the inner race and the outer race of the bearing, may be arranged such that the rolling elements form an annular row within the sheave. In some examples, the rolling elements are selected to be one of ball bearing, cylindrical rollers, spherical rollers, tapered rollers, or needle rollers. In some examples, the rolling elements are ball bearings arranged between the inner race and the outer race of the bearing such that the ball bearings form an annular row within the sheave. In some examples, the annular row is centred on the sheave axis such that rotation of the ball bearing, and corresponding rotation of the sheave, is centred on the sheave axis.

In some examples, the sheave comprises two (or more) annular rows of ball bearing. For example, the sheave may comprise two bearings (e.g. each comprising an inner race, an outer race, and an annular row of ball bearings disposed therebetween), wherein the two bearings (and thus annular rows of ball bearings) are arranged in parallel, centred on the sheave axis.

In some examples, the two (or more) bearings are engaged with different (e.g. axially spaced apart) portions of the inner surface of the cylindrical sleeve. For example, in examples comprising two (or more) annular rows within a single bearing, the two (or more) annular rows may be respectively seated on axial left (distal) and right (proximate) sides of radial inner ball seating grooves. For example, in examples comprising two (or more) annular rows in two (or more) bearings, the bearings may be respectively seated on axial left (distal) and right (proximate) sides of the (e.g. radial) annular rib on the inner surface.

According to a second aspect of the present invention, there is provided a method of manufacturing a sheave for a passenger conveyor system according to claim <NUM>.

It has been recognised that contraction of the polymeric material upon cooling can create the engagement between an outer surface of the outer race and the inner surface of the cylindrical sleeve. In the absence of the outer race comprising any protrusions, the shrinkage of the cylindrical sleeve may result in a press fit engagement between the outer race of the bearing and the inner surface. This means that the bearing is held within the cylindrical cavity once the manufacturing method is complete.

Examples according to this second aspect of the invention use a disc gate injection moulding process as already described above for injecting the polymer-based composite material into a mould.

In some examples, the melting temperature to which the material is heated is to a temperature above the melting temperature of the polymer-based matrix material (e.g. the polymer into which the (e.g. glass, e.g. carbon) fibres are dispersed) but below the melting temperature of the (e.g. glass, e.g. carbon) fibres dispersed therein such that the glass fibres remain in (e.g. solid) fibre form before, during and after the injection steps. Thus, the polymer-based composite material is the temperature at which the polymer matrix melts (e.g. transitions from a solid state to a liquid state) such that the polymer matrix with the (e.g. glass, e.g. carbon) fibres dispersed therein may be injected into the mould, via a disc injection gate.

In some examples, the preparing step comprises heating the polymer-based composite material to a temperature above <NUM>, e.g. above <NUM>, e.g. above <NUM>, e.g. above <NUM>, e.g. above <NUM>, e.g. between <NUM> and <NUM>.

In some examples, the step of combining (e.g. mixing, e.g. dispersing) the (e.g. glass, e.g. carbon) fibre with the polymer-based material occurs before the polymer-based material (that forms the polymer matrix) is heated to a temperature above the polymer-based material's melting temperature. For example, the (e.g. glass, e.g. carbon) fibre and the polymer-based material are combined when the polymer-based material is substantially a solid (e.g. in granular form or the like).

In some examples, the step of combining (e.g. mixing, e.g. dispersing) the (e.g. glass, e.g. carbon) fibre with the polymer matrix occurs after the polymer-based material (that forms the polymer matrix) has been heated to a temperature above the polymer-based material's melting temperature. For example, the (e.g. glass, e.g. carbon) fibre and the polymer-based material are combined when the polymer-based material is substantially a liquid.

In some examples, the step of combining (e.g. mixing, e.g. dispersing) the (e.g. glass, e.g. carbon) fibre within the matrix occurs as the polymer-based material (that forms the polymer matrix) is being heated to a temperature above the polymer-based material's melting temperature. For example, the (e.g. glass, e.g. carbon) fibre and the polymer-based material are combined when the polymer-based material is transitioning from a solid to a liquid state.

In some examples, the inner surface of the cylindrical sleeve comprises a first dimension (e.g. diameter). For example, the cylindrical cavity may have a first diameter when the cylindrical sleeve is in an expanded state. The expanded state may be provided when the cylindrical sleeve (e.g. the material making the cylindrical sleeve) is at an elevated temperature during the injection moulding step. Following injection moulding of a polymeric material or a polymer-based composite material, the elevated temperature may be a temperature above the material's glass transition temperature (Tg), e.g. above <NUM>, e.g. above <NUM>, e.g. above <NUM>, e.g. above <NUM>).

In some examples, the bearing is inserted into the cylindrical cavity when the cylindrical cavity comprises the first dimension (e.g. the cylindrical cavity is provided in an expanded state). For example, the bearing may be inserted into the cylindrical cavity (with or without the application of pressure) when the material of the cylindrical sleeve is at any elevated temperature (e.g. above the material's glass transition temperature), e.g. above <NUM>, e.g. above <NUM>, e.g. above <NUM>, e.g. above <NUM>, with subsequent cooling of the cylindrical sleeve to ambient temperature then creating an engagement between an outer surface of the outer race and the inner surface of the cylindrical sleeve. The subsequent cooling of the cylindrical sleeve to ambient temperature may result in the cylindrical cavity comprising a second dimension that is less than the first dimension (e.g. the cylindrical cavity cools to a contracted state). Thus the cylindrical cavity contracts around the bearing to create the engagement therebetween.

The subsequent cooling may take place naturally. In some examples, the method further comprises a step of cooling the cylindrical sleeve, after the bearing has been inserted, to a cooled temperature (e.g. below the material's glass transition temperature) e.g. below <NUM>, e.g. below <NUM>, e.g. to substantially room temperature.

In some examples, the second diameter of the cylindrical cavity is between <NUM> and <NUM>, e.g. between <NUM> and <NUM>, e.g. between <NUM> and <NUM>, e.g. between <NUM> and <NUM>, e.g. between <NUM> and <NUM>, e.g. between <NUM> and <NUM>.

In some examples, the contraction of the polymeric material of the cylindrical sleeve results in a press fit engagement between the outer race of the bearing and the inner surface such that the bearing is held within the cylindrical cavity via friction. This can be achieved without the outer race of the bearing comprising any protrusions.

In some examples, the outer race of the bearing is substantially plain (e.g. comprising a flat curved surface) such that the (e.g. press fit) engagement is formed between the (e.g. plain) outer race and the inner surface of the polymeric cylindrical sleeve by virtue of the outer race of the bearing having a diameter which is greater than or equal to a dimension (e.g. diameter) of the inner surface, with reference to the (second) diameter of the inner surface following cooling, i.e. the contracted state of the cylindrical sleeve described above. Within the meaning of the present disclosure, the dimension (e.g. diameter) of the outer race may be considered to be the linear measurement from one side of the outer race external surface to the other, passing through the sheave axis.

In other examples, the bearing may comprise protrusion(s), such that the protrusion(s) hold the bearing within the cylindrical cavity due to engagement between the protrusion(s) and the inner surface of the cylindrical sleeve. For example, the protrusion(s) comprise a longitudinal axis perpendicular to the outer race and the sheave axis. It will be appreciated that the protrusion(s) may have any suitable and/or desired height (e.g. distance over which the protrusion extends away from the surface of the outer race). The protrusion(s) may have a height between <NUM> and <NUM>, e.g. between <NUM> and <NUM>, e.g. between <NUM> and <NUM>. It will be appreciated that the protrusions may have any suitable and/or desirable shape.

Regardless of whether the outer race comprises protrusions or is plain, the equal or greater (e.g. effective) diameter of the outer race relative to the inner surface of the cylindrical cavity results in contact pressure at the interface between the outer race (e.g. plain outer race, e.g. protrusions) and the inner surface of the cylindrical sleeve in the contracted state, such that the contact pressure holds the bearing and cylindrical sleeve together (e.g. via friction) and they are substantially immovable with respect to each other. The bearing is thus held within the cylindrical cavity due to frictional engagement between the outer race (e.g. plain or comprising protrusion(s)) and the inner surface of the cylindrical sleeve.

The inner surface of the cylindrical sleeve in the contracted state may be moulded around the outer race (e.g. plain, e.g. comprising protrusions) of the bearing such that the shape of the inner surface of corresponds to the shape of the outer race. For example, if the second diameter of the cylindrical sleeve in the contracted state is smaller than the diameter of the (e.g. plain) outer race, it may be appreciated that, in the contracted state the inner surface may comprise an annular indentation (corresponding to the shape of the plain or flat outer race) into which the outer race engages. In such examples, the bearing is held by the press fit engagement between the outer race and the annular indentation on the inner surface of the cylindrical sleeve.

Preferably, the outer race comprises a (plurality of) indentation(s), preferably wherein each indentation is non-annular in shape (e.g. the indentation(s) do not extend annularly around the sheave axis along the circumference of the inner surface). In such examples, if the second diameter of the cylindrical sleeve in the contracted state is smaller than the effective diameter of the outer race comprising protrusion(s), the contraction of the cylindrical sleeve forms a (plurality of) indentation(s) (e.g. corresponding to the shape of a protrusion(s) on the surface of the outer race as described above) on the inner surface of the cylindrical sleeve as the inner surface contracts and moulds itself around the outer race comprising protrusions. The engagement between the protrusion(s) and the indentation(s) may thus comprise both a lock and key fit and a pressure fit.

In such examples, the bearing is held by the press fit engagement between the (e.g. at least one side of the) protrusion(s) of the outer race and the (e.g. at least one side of the) indentation(s) on the inner surface of the cylindrical sleeve, as well as being constrained from radial movement (e.g. around the sheave axis) due to engagement between the protrusion(s) and the indentation(s).

In some examples, the method comprises inserting a bearing while the cylindrical sleeve is still at an elevated temperature resulting from the injecting step. It will be appreciated that this elevated temperature may be lower than the injection temperature. The cylindrical sleeve may be allowed to at least partially cool before or during removal from the mould, i.e. before inserting the bearing.

However, in some other examples the cylindrical sleeve is allowed to completely cool following removal from the mould. In some examples, the method further comprises cooling the cylindrical sleeve, e.g. to a temperature below the material's glass transition temperature, e.g. below <NUM>, before the bearing is inserted into the cylindrical cavity. The bearing may then be inserted in a later manufacturing step that involves re-heating to an elevated temperature. In such examples of the third aspect, the method further comprises a secondary heating step (e.g. re-heating) wherein the cylindrical sleeve (e.g. after it has been allowed to cool following injection moulding) is heated to an elevated temperature, e.g. a temperature above <NUM>, e.g. a temperature above <NUM>, e.g. a temperature above <NUM>. The elevated temperature at which the bearing is inserted into the cylindrical cavity can be any temperature that enables subsequent cooling to create an engagement with the bearing.

The material is a polymer-based composite material, for example a polymeric (e.g. thermoplastic) matrix with fibre reinforcement dispersed therein. The polymer matrix may comprise a homopolymer, a heteropolymer, a block co-polymer (e.g. di-block polymers, e. g tri-block polymers), or any suitable and/or desirable blend or mixtures thereof. In some examples the polymers forming the polymer matrix may be natural or synthetic. Preferably the (e.g. blend of) polymer(s) forming the polymer matrix comprise thermoplastic polymer(s) suitable for use in an injection moulding process for the manufacture of the cylindrical sleeve.

In some examples the polymeric matrix comprises a polyamide (e.g. aliphatic polyamide, polyphthalamide and/or aramid) or a polyacrylamide. In some examples, the polymeric matrix comprises Nylon <NUM> and/or Nylon <NUM>.

In some examples, the polymer-based composite material comprises a (e.g. thermoplastic) polymer matrix including (e.g. glass, e.g. carbon) fibre reinforcement. In some examples, the polymeric material may be a carbon fibre reinforced polymer. In some examples, the polymeric material is a carbon fibre reinforced polyamide or polyacrylamide. For example, the polymeric material may be carbon fibre reinforced Nylon <NUM> or glass fibre reinforced Nylon <NUM>, or combinations and blends thereof.

In some examples, the polymeric material may be a glass fibre reinforced polymer (GFRP). In some examples, the polymeric material is a glass fibre reinforced polyamide or polyacrylamide. For example, the polymeric material may be glass fibre reinforced Nylon <NUM> or glass fibre reinforced Nylon <NUM>, or combinations and blends thereof. In some examples, the glass fibres comprise or consist of silicon dioxide (SiO<NUM>).

The inventors have recognised that disc gate injection moulding may be well-suited to moulding a polymer-based composite sheave containing long fibre reinforcement and/or a relatively high proportion of fibre reinforcement. Thus, the injecting step comprises injecting the polymer-based composite material into the mould via a disc gate.

In some examples, the (e.g. glass, e.g. carbon) fibre reinforcement comprises long (e.g. glass, e.g. carbon) fibres, e.g. (e. g glass, e.g. carbon) fibres comprising a length (e.g. an end to end length) of between <NUM> and <NUM>. In some examples, the (e.g. glass, e.g. carbon) fibre reinforcement is predominantly all long (e.g. glass, e.g. carbon) fibres, e.g. more than <NUM> wt. % of the (e.g. glass, e.g. carbon) fibre reinforcement is long (e.g. glass, e.g. carbon) fibres, e.g. more than <NUM> wt. % of the (e.g. glass, e.g. carbon) fibre reinforcement is long (e.g. glass, e.g. carbon) fibres, e.g. more than <NUM> wt. % of the (e.g. glass, e.g. carbon) fibre reinforcement is long (e.g. glass, e.g. carbon) fibres.

In some examples, the polymeric material comprises between <NUM> wt. % to <NUM> wt. % (e.g. long) (e.g. glass, e.g. carbon) fibres (e.g. wherein the (e.g. glass, e.g. carbon) fibre is dispersed within the polymer matrix). For example, the polymeric material may comprise between <NUM> wt. % to <NUM> wt. % (e.g. long) (e.g. glass, e.g. carbon) fibres, e.g. between <NUM> wt. % to <NUM> wt. % (e.g. long) (e.g. glass, e.g. carbon) fibres, e.g. between <NUM> wt. % to <NUM> wt. % (e.g. long) (e.g. glass, e.g. carbon) fibres.

In some examples, the polymeric material is selected from the Ultramid® range manufactured by BASF Chemical Company Group (Germany), for example, glass fibre reinforced Ultramid®.

One or more parameters of the injection moulding process may be varied so as to produce a cylindrical sleeve according to the examples below.

In some examples, the core comprises substantially all of the (e.g. glass, e.g. carbon) fibres present within the cylindrical sleeve, e.g. the core comprises substantially all of the between <NUM> wt. % to <NUM> wt. % (e.g. long) (e.g. glass, e.g. carbon) fibres dispersed within the polymeric material of the entire cylindrical sleeve. For example, the core may comprise between <NUM> wt. % to <NUM> wt. % (e.g. long) (e.g. glass, e.g. carbon) fibres, e.g. between <NUM> wt. % to <NUM> wt. % (e.g. long) (e.g. glass, e.g. carbon) fibres, e.g. between <NUM> wt. % to <NUM> wt. % (e.g. long) (e.g. glass, e.g. carbon) fibres dispersed within the polymeric material of the entire cylindrical sleeve. In some examples, the core comprises between <NUM> wt. % to <NUM> wt. % (e.g. long) (e.g. glass, e.g. carbon) fibres dispersed within the core polymeric matrix. For example, the core may comprise between <NUM> wt. % to <NUM> wt. % (e.g. long) (e.g. glass, e.g. carbon) fibres, e.g. between <NUM> wt. % to <NUM> wt. % (e.g. long) (e.g. glass, e.g. carbon) fibres, e.g. between <NUM> wt. % to <NUM> wt. % (e.g. long) (e.g. glass, e.g. carbon) fibres dispersed within the core polymeric matrix.

In some examples, the (e.g. two) surface layers comprise less than <NUM> wt. % (e.g. glass, e.g. carbon) fibres, e.g. less than <NUM> wt. % (e.g. glass, e.g. carbon) fibres, e.g. less than <NUM> wt. % (e.g. glass, e.g. carbon) fibres, e.g. less than <NUM> wt. % (e.g. glass, e.g. carbon) fibres, e.g. less than <NUM> wt. % (e.g. glass, e.g. carbon) fibres, e.g. less than <NUM> wt. % (e.g. glass, e.g. carbon) fibres, e.g. less than <NUM> wt. % (e.g. glass, e.g. carbon) fibres.

In some examples, the core further comprises an outer portion, an inner portion and a central portion sandwiched between the outer and inner portions. The outer and inner portions include (e.g. glass, e.g. carbon) fibres that are predominantly aligned in parallel with the outer and inner surfaces of the cylindrical sleeve respectively. The central portion, sandwiched therebetween, includes (e.g. glass, e.g. carbon) fibres that are predominantly randomly orientated. In such examples, alignment of the (e.g. glass, e.g. carbon) fibres in parallel with the inner and outer surface helps to improve the mechanical properties, such as the tensile strength, of the cylindrical sleeve such that the sheave is able to withstand the high loads required for use within elevator systems whilst improving resistance to stress fractures or breakage.

For example, the injecting step produces a cylindrical sleeve comprising an outer portion wherein the (e.g. glass, e.g. carbon) fibres are predominantly aligned with the outer surface, a central portion radially inward of the outer portion wherein the (e.g. glass, e.g. carbon) fibres are predominantly arranged randomly, and an inner portion radially inward of the central portion wherein the (e.g. glass, e.g. carbon) fibres are predominantly aligned with the inner surface.

Within the meaning of the present disclosure, the glass transition temperature (Tg) of a material is intended to define the temperature at which a polymeric material (or polymer-based composite material) transitions from a hard or brittle state to a soft or rubber state. Similarly, the melting temperature of a material is intended to define the temperature at which a material transitions from a "solid" to a liquid state. It will be appreciated that the melting temperature for a polymeric material will be at a temperature above the glass transition temperature and thus the "solid" state of the polymer before melting may be soft or deformable. The glass transition temperature and melting temperature are well known in the art and may be measured via a number of industry standard techniques as described below:.

The present disclosure as defined by any of the aspects described above and/or the appended claims thus provides a number of advantages over conventionally available (e.g. steel) sheaves. For example, this disclosure provides a sheave with mechanical properties (e.g. tensile strength) suitable for use in an elevator system at a lower cost than corresponding steel sheaves. For example, the disclosed sheaves and manufacturing methods help to minimise the number of manufacturing steps required and thus reduce the costs associated with the component manufacture, without negatively impacting the mechanical strength, durability or safety of the component when in use.

The sheaves disclosed herein are for use in a passenger conveyor system, such as an elevator system, escalator system, moving walkway or the like. The sheaves may be particularly suitable for use as a deflector sheave in an elevator system.

Some examples of the present disclosure as defined by the appended claims are illustrated further by way of the following non-limiting examples and the accompanying figures, in which:.

<FIG> shows a sheave <NUM> comprising a cylindrical sleeve <NUM> and two bearings 120a, 120b, all centred on a sheave axis <NUM> such that the sheave rotates about the sheave axis <NUM>. <FIG> shows an exploded view of the sheave <NUM>. The cylindrical sleeve <NUM> includes an outer surface <NUM> and an inner surface <NUM>. The outer surface <NUM> includes a groove <NUM> which is arranged to receive a belt (not shown) in use. The inner surface <NUM> defines a cylindrical cavity <NUM> which is centred on the sheave axis <NUM>. It can be seen that the right hand bearing 120a includes an outer race 125a, an inner race 130a and a plurality of rolling elements 135a arranged between the outer race 125a and the inner race 130a. The left hand bearing 120b has the same structure. The bearing 120a, 120b is held within the cylindrical cavity <NUM>, against the inner surface <NUM> of the cylindrical sleeve <NUM>. The outer race 125a is shown in this example to comprise a plurality of protrusions <NUM>, distributed evenly around the outer race 125a and having a substantially trapezoidal first cross-sectional shape. <FIG> shows a perspective view of the cylindrical sleeve <NUM>. It can be seen that the inner surface <NUM> of the cylindrical sleeve <NUM> comprises indentations <NUM> arranged to engage with the protrusions <NUM>. In this example, the indentations <NUM> have a shape corresponding to a negative shape of the protrusions <NUM>.

<FIG> shows an example of a disc gate injection mould <NUM> used to make a cylindrical sleeve <NUM>. The mould <NUM> comprises an outer casting component <NUM> and an inner casting component <NUM>. The outer casting component <NUM> includes the negative impression of the outer surface <NUM> of the cylindrical sleeve <NUM> such that when a polymer-based composite material is introduced into the outer casting component <NUM>, the outer surface <NUM> of the cylindrical sleeve <NUM>, including the groove <NUM>, is formed.

As shown in <FIG>, the outer casting component <NUM> may be made of multiple segments 202a, 202b which fit together to provide the mould for the outer surface <NUM>. Preferably, when fitted together, the outer casting component segments 202a, 202b provide a continuous surface such that there is substantially no meld line on the outer surface <NUM> of the cylindrical sleeve <NUM> after moulding has occurred by the disc gate injection of molten material. It will be appreciated that the outer casting component <NUM> may be formed of any desired number of segments, e.g. one, two, three, four and so on. The number of segments may be selected based on economic principles (e.g. cost effectiveness of producing the mould and/or using the mould) as well as practicality (e.g. such as the ease of removing the cylindrical sleeve <NUM> from the mould <NUM>).

<FIG> shows the cross-section of the inner casting component <NUM> shown in <FIG> in a plane parallel to the sheave axis <NUM>, after removal of the outer casting component <NUM> to leave the exposed outer surface <NUM> of the moulded cylindrical sleeve <NUM>.

As shown in <FIG>, the inner casting component <NUM> is provided within the outer casting component <NUM> such that the inner casting component <NUM> and the outer casting component <NUM> form a mould cavity that, when filled with the injected material, produces the shape of the cylindrical sleeve <NUM>. The inner casting component <NUM> thus provides the negative mould of the shape of the inner surface <NUM> of the cylindrical sleeve <NUM>. As shown in <FIG>, the inner surface <NUM> in the example shown includes two annular rib(s) <NUM> and thus the inner casting components 204a and 204b include the negative imprint of said annular rib(s) <NUM> such that they are formed on moulding. The inner casting component <NUM> is preferably made from at least two segments 204a, 204b separated by a disc gate <NUM> which is used to inject the material into the mould cavity.

The mould <NUM> shown in <FIG> thus allows the cylindrical sleeve <NUM> to be manufactured as a unitary (e.g. single) piece from material injected therein via a disc gate injection system <NUM>. For example, polymeric material may be heated and then injected, through disc gate injection system <NUM> into the disc gate <NUM> which provides the polymeric material to the mould <NUM> such that material is provided evenly to all radial positions of the mould cavity.

The inventors have found that, through use of a disc gate <NUM>, a cylindrical sleeve <NUM> may be produced that has improved physical properties (e.g. tensile strength, surface roughness, durability) which make the cylindrical sleeve <NUM> suitable for use in a sheave <NUM> for an elevator system or other passenger conveyor system.

<FIG> shows an example of manufacturing a cylindrical sleeve via an injection moulding process that uses a four point injection gate comprising four runners <NUM> that input the material into the mould at four radial positions. As can be seen from <FIG>, injection of the material in this manner results in the spreading of material radially around the mould (for example the mould <NUM> shown in <FIG>) from four epicentres <NUM> corresponding to the four injection site positions. This results in a knit, or meld, line <NUM> where the front of material radiating outwards from different epicentres <NUM> meet. As seen in <FIG>, the fibres are randomly oriented (as represented by the darkest colour) only at the epicentres <NUM>. As uniformity of the material at the meld line (e.g. the orientation of (e.g. glass, e.g. carbon) fibres) may be disrupted, this may result in unfavourable physical properties in the moulded component at the site of the meld, e.g. unfavourable surface defects or reduced tensile strength leading to breakage at lower loads.

<FIG> shows the resultant fibre orientation when a long (e.g. glass, e.g. carbon) fibre reinforced polymer is injected into the mould <NUM> (shown in <FIG>) via the four site injection gate shown in <FIG>. The results clearly show that at positions <NUM> corresponding to the epicentres <NUM> the fibre orientation is substantially uniform with a value of between <NUM> and <NUM>. In contrast, at the meld line <NUM> the fibre orientation reaches the undesirable value of <NUM>, representing a directional alignment.

In contrast, the inventors have found these unfavourable characteristics are improved by use of disc gate injection as shown in <FIG>.

In addition to the improvements described above, disc gate injection moulding helps to provide the unexpected result that, when the polymeric material injected via the disc gate comprises long (e.g. glass, e.g. carbon) fibres, the long (e.g. glass, e.g. carbon) fibres exhibit unique and advantageous alignment properties in the cylindrical sleeve.

<FIG> shows a cross-sectional view of the groove <NUM> in a plane parallel to the width of the groove. As shown in <FIG>, the groove <NUM> is formed between the outer casting component <NUM> and the inner casting component <NUM> of a mould where, in the example shown, the outer casting component <NUM> provides for a crowned (e.g. curved) surface <NUM> across the width of the groove <NUM>.

As shown in <FIG>, across the thickness of the groove (e.g. in the direction extending from the inner surface <NUM> of the cylindrical sleeve to the groove surface <NUM>) there are several zones or regions of (e.g. glass, e.g. carbon) fibre alignment. In particular, <FIG> shows that the cylindrical sleeve (represented by the groove <NUM>) includes a first surface layer <NUM> proximate to the outer surface <NUM> formed by the outer casting component <NUM>, a second surface layer <NUM> proximate to the inner surface <NUM> formed by the inner casting component <NUM> and a core region, wherein the core region comprises an outer portion <NUM> proximate to the first surface layer <NUM>, an inner portion <NUM> proximate to the second surface layer <NUM> and a central portion <NUM> sandwiched between the outer portion <NUM> and inner portion <NUM>. The first surface layer <NUM>, second surface layer <NUM>, outer portion <NUM>, inner portion <NUM> and the central portion <NUM>, as shown in <FIG>, all exhibit different (e.g. glass, e.g. carbon) fibre polymer characteristics and properties.

The first and second surface layers <NUM>, <NUM> comprise a low (e.g. glass, e.g. carbon) fibre content, such that the outer surface <NUM> and inner surface <NUM> of the cylindrical sleeve are polymer-rich with substantially no (e.g. glass, e.g. carbon) fibre content by weight. This helps to provide the advantage that the generation of electrostatic charges on the surface of the belt and/or sheave (which may contribute to degradation or wear of the belt if present) is minimised without the need of costly or time consuming post production steps (such as polishing). Another advantage of the absence of fibre reinforcement in the surface layers <NUM>, <NUM> is that the outer surface <NUM> and inner surface <NUM> can be smooth (e.g. glossy) without any fibres interrupting the smooth surface finish. This can be desirable for belt traction.

The outer and inner portions <NUM>, <NUM> in comparison to the first and second surface layers <NUM>, <NUM> comprise a high percentage by weight of (e.g. glass, e.g. carbon) fibres. Furthermore, the long (e.g. glass, e.g. carbon) fibres present in the outer and inner portions <NUM>, <NUM> are highly oriented in parallel with the outer surface <NUM> and inner surface <NUM>. This high degree of orientation has been shown to improve the physical properties, such as the strength and load capacity, of the sheave such that the sheave, comprising the polymeric cylindrical sleeve, is suitable for use within an elevator system.

The central portion <NUM>, sandwiched between the outer and inner portions <NUM>, <NUM>, includes (e.g. glass, e.g. carbon) fibres that are predominantly randomly orientated and, in combination with the outer and inner portions <NUM>, <NUM> contribute to the overall physical and mechanical properties of the cylindrical sleeve such that the sheave is able to withstand the high loads required for use within elevator systems whilst improving resistance to stress fractures or breakage.

<FIG> shows some exemplary methods <NUM> of manufacturing a sheave which will be discussed with reference to <FIG>, <FIG> and <FIG>.

The material used to make the cylindrical sleeve of the sheave is a polymer-based composite material.

The method <NUM> first requires the material to be prepared at step <NUM> for moulding. The preparing step <NUM> for a polymer-based composite material includes heating the material to a temperature above the melting point of the polymer. The preparing step <NUM> optionally includes adding a fibre reinforcement in advance of the moulding step <NUM>. Once heated, the material is introduced (e.g. injected) at step <NUM> into the mould <NUM> (arranged to produce the cylindrical sleeve <NUM> described herein) via a disc gate <NUM> as seen in <FIG> or via another suitable moulding process. The moulding step <NUM> optionally includes adding a fibre reinforcement. Once the material has been injected within the mould, the material is allowed to partially cool to a temperature below the material's melting temperature before removing at least the inner casting component <NUM> at step <NUM>. By allowing the material to partially cool, it is ensured that the material substantially retains the shape of the mould cavity to provide the desired shape of the cylindrical sleeve <NUM>. Step <NUM> relates to this partial cooling which makes it possible to remove at least part of the mould.

After the inner casting component <NUM> has been removed at step <NUM>, the cylindrical sleeve may be allowed to cool (or actively cooled) at step <NUM> before the bearing(s) 120a, 120b, 820a, 820b are inserted into the cylindrical cavity <NUM> at step <NUM>. In such embodiments, the outer race 125a, 125b of the bearings 120a, 120b, 820a, 820b comprise protrusions <NUM>, 840a, 840b as shown in <FIG>, <FIG>, <FIG>, 8A and 8B, such that when the bearing is inserted (e.g. upon the application of pressure) the protrusions form a press fit engagement between the outer race 125a, 125b, <NUM>, <NUM> of the bearings 120a, 120b, 820a, 820b and the inner surface <NUM>. The application of pressure when inserting the bearings 120a, 120b, 820a, 820b may further form indentations on the inner surface <NUM> (e.g. the inner surface <NUM> of the cylindrical sleeve plastically deforms upon the application of the pressure required to insert the bearings 120a, 120b, 820a, 820b) such that the protrusions and indentations form a lock and key fit between the protrusions <NUM> and the indentations <NUM>.

Alternatively, the bearings 120a, 120b, 820a, 820b, 820c may be inserted into the cylindrical cavity <NUM> at step <NUM> whilst the cylindrical sleeve is at an elevated temperature, e.g. a temperature above the glass transition temperature Tg for a polymeric material or a temperature slightly below the melting temperature for a metallic material. The cylindrical sleeve <NUM> is then allowed to finally cool at step <NUM> to an ambient temperature such that the inner surface <NUM> of the cylindrical sleeve <NUM> contracts in size and moulds (or deforms) around the outer race <NUM> of the bearing 120a, 120b, 820a, 820b, 820c. Thus contraction of the cylindrical sleeve <NUM> results in a press fit engagement between the outer race <NUM>, <NUM>, <NUM>, <NUM> and the inner surface <NUM> of the cylindrical sleeve <NUM>.

When the outer race 125a, 125b, <NUM>, <NUM> comprises protrusions <NUM>, 840a, 840b as shown in <FIG>, <FIG>, <FIG>, <FIG>, the contraction of the cylindrical sleeve <NUM> on cooling (e.g. below the glass transition temperature) forms indentations <NUM> on the inner surface <NUM> of the cylindrical sleeve <NUM>, resulting in a press fit engagement between the outer race 125a, 125b, <NUM>, <NUM> of the bearings 120a, 120b and the inner surface <NUM> that includes a lock and key fit between the protrusions <NUM>, 840a, 840b and the indentations <NUM>.

During use of the sheave <NUM>, stress relaxation of a polymeric cylindrical sleeve <NUM> can also result in the protrusions <NUM> becoming more embedded in the inner surface <NUM> by deepening the indentations <NUM>. This further ensures reliable performance without rotational sliding between the bearing <NUM> and the cylindrical sleeve <NUM>.

<FIG> show cross-sectional views of the sheave <NUM> (shown in <FIG>), a bearing outer race <NUM>, and a bearing <NUM>, respectively, in the plane perpendicular to the sheave axis <NUM>.

The cylindrical sleeve <NUM> comprises an outer surface <NUM> and an inner surface <NUM>, wherein the inner surface <NUM> is adjacent to the bearing <NUM>. The bearing <NUM> comprises an outer race <NUM>, an inner race <NUM> and a plurality of ball bearings <NUM> (or other rolling bearings) disposed therebetween. The outer race <NUM> includes a plurality of protrusions <NUM> having a substantially trapezoidal first cross-sectional shape such that the outer race <NUM> has a cogged surface shape. As shown in <FIG>, the protrusions <NUM> are received within indentations <NUM> having a corresponding shape such that the protrusions <NUM> engage the indentations <NUM> to provide a lock and key fit, as well as a press fit between the outer race <NUM> and the inner surface <NUM> due to its smaller diameter, to hold the bearing <NUM> within the cylindrical cavity <NUM>.

<FIG> and <FIG> show cross-sectional views of three different bearing examples 820a, 820b, 820c. All three examples shown have an outer race <NUM>, <NUM>, <NUM>, an inner race <NUM> and a plurality of ball bearing elements <NUM> disposed therebetween.

<FIG> show examples wherein the outer race <NUM>, <NUM> further comprises a plurality of protrusions 840a, 840b. The bearing 820a shown in <FIG> has four protrusions 840a arranged evenly around the outer race <NUM> (e.g. at <NUM> degrees relative to each other). The protrusions 840a have a substantially square first cross-sectional shape. The bearing 820b shown in <FIG> has three protrusions 840b arranged evenly around the outer race <NUM> (e.g. at <NUM> degrees relative to each other). The protrusions 840b have a substantially triangle first cross-sectional shape with a curved or rounded top corner (e.g. the corner pointing away from the sheave axis). It will be appreciated that by rounding the edges of the protrusions 840b, the concentration of stress will be minimised when the bearing engages the inner surface. Additionally, the rounded edge increases the surface area of the protrusion which in turn will increase the area over which friction arises between the outer race <NUM> and the inner surface <NUM> of the cylindrical sleeve <NUM> (e.g. as seen in <FIG>). <FIG> shows a bearing 820c wherein the outer race <NUM> is plain (e.g. flat) and does not comprise any protrusions.

<FIG> shows another method <NUM> of manufacturing a sheave which will be discussed with reference to all preceding figures.

The method <NUM> first requires a material to be prepared for the moulding process at step <NUM>, including heating the material to a temperature above the (matrix) material's melting point. Once heated, the material is introduced (e.g. injected) at step <NUM> into the mould <NUM> (arranged to provide the cylindrical sleeve <NUM> described herein). Once the material has been injected within the mould, the material is allowed to cool at step <NUM>, at least to a temperature below the material's melting temperature, but preferably to room temperature, before removing the mould. The sleeve may then be stored at step <NUM>.

The cylindrical sleeve <NUM> may then optionally be reheated at step <NUM> to provide the cylindrical sleeve at an elevated temperature (e.g. a temperature above the glass transition temperature Tg for a polymeric material). The bearings 120a, 120b, 820a, 820b, 820c are inserted at step <NUM> into the cylindrical cavity <NUM> whilst the cylindrical sleeve <NUM> is at an elevated temperature, e.g. a temperature above the glass transition temperature Tg for a polymeric material. The cylindrical sleeve <NUM> is then allowed to cool at step <NUM> (e.g. to ambient temperature, e.g. to a temperature below the glass transition temperature Tg) such that the inner surface <NUM> of the cylindrical sleeve <NUM> contracts in size and moulds (or deforms) around the outer race <NUM> of the bearing 120a, 120b, 820a, 820b, 820c.

The contraction of the cylindrical sleeve <NUM> on cooling forms a press fit between the outer race <NUM>, <NUM>, <NUM>, <NUM> of the bearings 120a, 120b, 820a, 820b, 820c and the inner surface <NUM> of the cylindrical sleeve <NUM>. This may form indentation(s) <NUM> on the inner surface <NUM> of the cylindrical sleeve <NUM> which correspond to the shape of any protrusions <NUM>, 840a, 840b, present on the outer race <NUM> such that the press fit engagement includes a lock and key fit between the protrusions <NUM>, 840a, 840b on the outer race and the corresponding indentations <NUM> on the inner surface <NUM> of the cylindrical sleeve. However, it will be appreciated that this method <NUM> may also be used to insert a bearing absent any protrusions.

Claim 1:
A cylindrical sleeve (<NUM>) for a sheave (<NUM>) for a passenger conveyor system, the cylindrical sleeve (<NUM>) comprising:
an outer surface (<NUM>, <NUM>) comprising a groove (<NUM>) arranged to receive a belt; and
an inner surface (<NUM>) defining a cylindrical cavity (<NUM>);
wherein the cylindrical sleeve (<NUM>) is substantially made of a polymer-based composite material including a polymeric material with fibre reinforcement, and wherein the cylindrical sleeve (<NUM>) is made by disc gate injection moulding; further wherein the cylindrical sleeve (<NUM>) comprises:
a core (<NUM>) made of the polymeric material with a first weight percentage of fibre reinforcement; and characterized in that the sleeve further comprises:
two surface layers (<NUM>, <NUM>) defining the outer surface (<NUM>, <NUM>) and the inner surface (<NUM>, <NUM>), respectively, wherein the surface layers (<NUM>, <NUM>) are made of the polymeric material with a second weight percentage of fibre reinforcement;
wherein the second weight percentage of fibre reinforcement is lower than the first weight percentage of fibre reinforcement.