Field of the I nvention

This invention relates generally to an escalator truss. Background of the I nvention

Escalators or moving walkways are well known and in widespread use. Such devices typically comprise a conveyor belt, in the form of a stepped belt or transporting belt, arranged inside a truss or frame which defines the configuration of the escalator or moving walkway within the building or structure. The truss is essentially a supporting structure for the conveyor belt and other elements of the device, and is formed as a lattice structure and assembled from a plurality of longitudinal, vertical and/or diagonal bars which are typically formed of steel. Such assembly is performed prior to transport to the building or structure in which it is to be installed. For example, when a new escalator is installed in an underground system such as a subway or tube station, it is common practice to remove the mechanical elements from the truss, and then, either remove the existing truss altogether by dry cutting it into sections and moving it from the site or, as a less expensive option, place a second, smaller truss inside the original one, thereby avoiding the expense of removing the existing truss.

In both cases, however, the process entails very lengthy and expensive civil works for the surrounding structure. The new truss is delivered as a single assembled steel section which often requires demolition of part of the platform and station to deliver and position the new truss, and also closure of the track whilst a specialist flatbed train is used to deliver the new truss and throughout the time it takes to complete the works. If the original truss is being left in place, the new truss still needs to be delivered and positioned. In view of the typical construction of escalator trusses of this type, they must be delivered in as few sections as possible to ensure structural integrity when in place, and the size of these sections once again requires demolition of parts of the surrounding structure and the use of heavy lifting equipment to position and fix the new truss within the existing truss assembly.

There is a need to provide a new truss and truss assembly that is easier and quicker to deliver and install, and that does not require demolition of parts of the surrounding structure or unnecessary disruption to local services, and aspects of the present invention seek to address at least some of these issues. Summary of the Invention

In accordance with an aspect of the present invention, there is provided a modular escalator or moving walkway truss, comprising a plurality of truss sections connected together end-to-end, each truss section comprising a base portion and a pair of side portions all formed of a fire resistant composite material. The composite material can comprise a fire resistant reinforced thermoplastic material. The base portion and side portions of each truss section can be integrally formed by a moulding process, for example, compression moulding or resin transfer moulding.

The truss can comprise at least three truss sections connected together end-to-end by mechanical fixtures and/or chemical adhesion or bonding, for example. In the case of an escalator truss, the truss can comprise a first end truss section shaped and configured to define an angular incline relative to an upper position above, at least one middle truss section defining a substantially straight path along the angular incline, and a second end truss section defining a return from the angular incline to a substantially horizontal orientation at the upper position.

The middle truss section can comprise a substantially rectangular planar frame defining elongate side edges and opposing orthogonal end edges, and a plurality of elongate struts arranged in parallel and spaced apart arrangement between the side edges. An end truss section can comprise a base portion comprising a frame defining a generally rectangular footprint and comprising a first, planar section and an integral second section extending at an angle to the first section. Each truss section can have a length of no more than 5 metres, or no more than 3 metres. Each truss section can comprise one or more fixture portions configured to enable the truss to be attached to a fixed structure.

In accordance with another aspect of the present invention, there is provided a kit of parts for assembling a truss for an escalator or moving walkway, comprising a plurality of truss sections, each truss section comprising a base portion and a pair of side portions all formed of a fire resistant composite material.

According to another aspect of the present invention, there is provided a truss section for the above-described kit of parts, the truss section comprising a base portion and a pair of side portions all formed of a fire resistant composite material.

In accordance with another aspect of the present invention, there is provided a method of forming a truss for a moving walkway, the method comprising the steps of providing a plurality of individual truss sections, each truss section comprising a base portion and a pair of side portions all formed of a fire resistant composite material, and connecting the truss sections together end-to-end.

These and other aspects of the present invention will be apparent from the following detailed description. Brief Description of the Drawings

Embodiments of the present invention will now be described, by way of examples only, and with reference to the accompanying drawings, in which:

Figure la is a schematic perspective view of a flat base portion of a truss section according to an embodiment of the present invention; Figure lb is a schematic perspective view of an angled base portion of a truss section according to an embodiment of the present invention;

Figure lc is a schematic perspective view of a straight side portion of a truss section according to an embodiment of the present invention;

Figure Id is a schematic perspective view of an angled side portion of a truss section according to an embodiment of the present invention;

Figure 2 is a schematic side perspective view of an escalator truss according to an embodiment of the present invention;

Figure 3a is a schematic perspective view of an escalator truss according to an embodiment of the present invention;

Figure 3b is a schematic side perspective view of an escalator including the truss of Figure 3a;

Figure 3c is a front perspective view of the escalator of Figure 3b;

Figure 3d is a schematic rear view of the escalator of Figure 3b;

Figure 4 is a schematic illustration of a vacuum bagging method suitable for use in manufacturing truss sections according to an embodiment of the present invention; Figure 5 is a schematic illustration of a compression moulding method; and

Figure 6 is a schematic illustration of a resin transfer moulding process.

Detailed Description

Thus, the present invention provides a method of assembling and installing an escalator truss, and the individual components required in such a method. Referring to Figures la to Id of the drawings, an escalator truss according to an embodiment of the present invention is assembled in situ using a plurality of individual elements. Thus, referring to Figure la of the drawings, a plurality of base sections 10 can be provided, each base section comprising a substantially rectangular frame 10a spanned by a plurality of spaced apart elongate bars 10b arranged in parallel . Referring to Figure lb of the drawings, an alternative base section 10' can be provided that still has a generally rectangular footprint but includes a bend 100 to accommodate an upward or downward bend in the assembled escalator truss, typically at the top or bottom of the structure.

Referring to Figure lc of the drawings, a plurality of side sections 12 can be provided, one for each elongate side edge of each rectangular base section, each side section comprising a generally rectangular frame 12a having a length equal to that of an associated base section 10, and having at least one strengthening member 12b extending laterally between the side edges of the frame 12a. In the embodiment illustrated, the strengthening member extends between diagonally opposing corners of the rectangular side section. Referring to Figure Id of the drawings, an alternative side section 12' can be provided comprising a frame 12a' comprised of two opposing parallel side edges, a first end edge that extends substantially orthogonally to the side edges, and a second end edge that comprises a first angled portion to correspond with a bend in a base section 10' and a second angled portion to match an angled joint between it and the rectangular side section, the two angled portions meeting at an off-centre point along the second end edge. In this case, a pair of strengthening members extends in a substantially V- shaped configuration between the two side edges.

The base sections 10, 10' and the side edges 12, 12' are selected to define any desired configuration to match the requirements of the building or structure in which the truss is to be installed. For example, referring to Figure 2 of the drawings, an escalator truss

14 is illustrated schematically, which comprises four rectangular base sections 10, and associated side sections 12, a first, angled base section 10' and associated side sections 12', at the base of the truss 14 (to define the upward slope of the truss) and a second, angled base section 10' and associated side sections 12' at the top of the truss (to define a return to horizontal at the upper end of the truss).

Base sections and associated side sections, together forming a truss section, can be made to accommodate any desired configuration of any desired length. Each base section can have a length of around 3 metres or less.

Each section of a truss, comprising a base section and a pair of opposing side sections, can be assembled prior to delivery to the installation location, or this can be done as part of the installation process. Thus, each truss section 16 comprises a base section having a longitudinal axis, with each corresponding side section being affixed at right angles to a longitudinal side edge thereof. The side and base sections can be so connected together by mechanical fixtures or chemical bonding, for example, or they could be formed as an integral structure comprising the base and side sections.

The base and/or side sections are provided with the required flanges and dedicated fixing points to enable the escalator mechanics to be attached to the assembled truss.

Each modular truss according to an embodiment of the invention can be walked in through the door of a building or delivered on a standard maintenance carriage (in a railway scenario) because the base and side sections can be no more than, say, 3 metres in length, and also because they can be formed of a very lightweight composite material, such as a fire rated reinforced thermoplastic composite material, examples of which include polyetherimide (PEI), Polyphenylene Sulfide (PPS), polyetheretherketone

(PEEK) and polyetherketoneketone (PEKK). In an embodiment, the base and/or side sections can be formed of a laminated structure comprising a pair of composite skins having therebetween a foam, honeycomb or corrugated structure. The composite skins can, for example, comprise a reinforced thermoplastic material such as fire rated reinforced thermoplastic composite material, examples of which include polyetherimide (PEI), Polyphenylene Sulfide (PPS), polyetheretherketone (PEEK) and polyetherketoneketone (PEKK). The intermediate material between the skins can comprise a thermoplastic, thermoplastic composite, paper, pressboard or aluminium, and can be bonded to adjacent surfaces of the skins by means of an adhesive, such as an epoxy resin adhesive. The use of a laminated material comprising skins of fire resistant composite material with a fire resistant foam or honeycomb core, not only enables the truss sections to be significantly lighter than if a traditional material such as steel were to be used, but also enables the assembled truss to be structurally efficient and surpass the current statutory fire regulations. A vacuum bagging technique can be used to further improve the quality of a composite material produced by a wet lay-up method.

Referring to Figure 4 of the drawings, in a vacuum bagging technique, sheet of material 31, such as a fire rated reinforced thermoplastic composite laminate having a foam or honeycomb core of a similar fire rated reinforced thermoplastic composite, is placed on a release film 30 positioned on the tool base 32 between two blocks of sealant 34.

The laminate sheet 31 is located between a pair of dams 36, and a number of layers of sheet material are positioned over the exposed surface of the laminated sheet 31, as follows: a layer of peel ply 37, a bleeder layer 38, and a release film 40. A breather layer 42 extends over the upper release film 40 and extends between the two sealant blocks 34. A bagging film 44 extends over the breather layer 42 and is secured at the sealant blocks 34 by pressure sensitive tape 46. A vacuum hose 48, including a vacuum valve 50 extends into the bagging film 44 at one side of the laminate, between the inner surface of the bagging film and the adjacent breather layer 42. On the side at which the vacuum hose 48 is located, a portion of flash tape 52 extends between the side of the laminated sheet 31 and the inner surface of the breather Iayer 42.

Thus, essentially, a bagging film 44 is placed around a 'laid up' composite material and is secured to the tool surface with sealant. Air is then evacuated from the bag (via the vacuum hose 48) leaving the composite under a pressure of up to 1 atmosphere, thereby forcing resin into any remaining voids and helping to ensure an even distribution. Higher viscosity resins can be used in comparison to the wet lay-up technique. As stated above, it is envisaged that each truss section, including a base section and corresponding side sections can be formed as an integral structure. There are a number of methods of forming such an integral truss structure, however two methods of forming the integral truss sections using a composite material, for example of the type described above, will now be briefly described. Referring to Figures 5a and 5b of the drawings, compression moulding can be used to shape polymer matrix composites of the type considered suitable for use in an embodiment of the invention. As illustrated schematically in Figure 5a, the composite material or 'charge' 60 is placed between two steel platens defining, respectively, an upper (movable) mould 62 and a lower (fixed) mould 64. Referring to Figure 5b of the drawings, the upper mould 60a is brought down onto the charge 60 which is subsequently heated and cured under pressure. An ejector pin 66 can be used to remove the moulded component from the lower mould 62b once the upper mould 62a has been lifted. This technique produces components with a high quality surface finish, whilst having a relatively short cycle time, making it highly suitable for processes where a high throughput is required. However, for lower volume production, high machine costs can make this process prohibitively expensive. Referring now to Figure 6 of the drawings, in an alternative method for forming integral truss sections, a resin transfer moulding process can be used. A resin moulding apparatus is illustrated schematically, and comprises an upper mould 70a and a lower mould 70b which, when clamped together by clamps 72 together define a cavity shaped in the form required to be produced. A two-part resin is used in the process, with each of the two elements (namely a low viscosity resin and a catalyst) being separately stored in vessels 74, 76 respectively. In use, a dry woven roving is placed in the lower mould 70b and the upper mould 70a is fixed in place. The low viscosity resin and catalyst are together injected under pressure into the mould cavity via a resin injector device 78, and it permeates the fibres of the dry woven roving. The composite material cures whilst in the mould. This technique can, beneficially be used for low volume production.

Referring now to Figures 3a to 3d, in a method of installing a truss according to an embodiment, a plurality of truss sections 16 are delivered to the site and a truss 14 is constructed by assembling the truss sections 16 in an end-to-end configuration, with an angled section 16' at the base, one or more straight sections 16 extending toward the upper floor, and terminating with another angled section 16'. The truss 14 illustrated schematically in Figure 3a is shown with a single straight truss section 16 between the two angled sections 16', but it will be understood that in practice, the number of intermediate (straight) truss sections will be dependent on their length, the distance between the upper and lower floors, and the footprint available to accommodate the truss (which will dictate the angle defined by the angled sections 16' as well). During assembly, the truss sections are connected together, either by mechanical fixtures or chemical bonding, depending on their position within the structure configuration.

Referring now additionally to Figures 3b to 3d of the drawings, the assembled truss 14 can be provided with all of the required flanges and dedicated fixing points to enable efficient attachment of the escalator mechanics 20 (such as drives for moving the conveyor belt and handrail, shafts, gears, gearwheels, chains, rails, etc), and the conveyor belt 22 can be arranged inside the truss 14 to complete the basic structure. A handrail 24 is typically provided along the side edges of the conveyor belt 22.

Thus, an embodiment of the present invention provides a method of installing a new escalator or moving walkway truss having component parts that are small and light enough to enable relatively easy delivery options, whilst eliminating the need and inherent danger of heavy lifting apparatus. The modular nature of the component parts circumvents the need for expensive and time consuming civil works to the platforms or delivery routes of the building or structure whilst the truss is positioned and installed, as well as eliminating the need to demolish any part of the structure or building during the delivery process. This, in turn, eliminates the need for costly transport closures, for example, during the delivery process, not only underground to the track network in the case of an underground railway application, but also above ground in respect of the transport network on public highways. In addition to all of that, a significantly reduced time scale for installation is achievable.

It will be apparent to a person skilled in the art, from the foregoing description, that modifications and variations can be made to the described embodiments without departing from the scope of the invention as defined by the appended claims.