WO2010086632A1

WO2010086632A1 - Shower tray

Info

Publication number: WO2010086632A1
Application number: PCT/GB2010/000179
Authority: WO
Inventors: Bruce Hutchon
Original assignee: Polyformers Limited
Priority date: 2009-02-02
Filing date: 2010-02-02
Publication date: 2010-08-05
Also published as: GB0901636D0

Abstract

A shower tray comprising an upper tray portion and a lattice support on a back of the upper tray portion, wherein the upper tray portion has a top layer that forms an external surface of the tray, and a base. The lattice defines a plurality of spaces that may be in filled with a material selected to strengthen the tray.

Description

Shower Tray

Field of the Invention

The present invention relates to a shower tray and method of manufacturing such a tray.

Background of the Invention

There are four basic manufacturing methods for making different types of shower tray depending on the durability, finish and cost the customer is looking for. Currently, the most popular is the acrylic tray. This is made using a sheet of acrylic material that is heated until soft and then clamped onto a mould in the shape of a tray. A vacuum is applied through the tray mould and the sheet is sucked onto the mould and sets in the desired shape. The manufacturer then adds a layer of fibreglass or wood on the inside to give some minimal strength and then makes a wooden or steel frame for the tray to sit on. This is the cheapest and fastest way to make a shower tray.

Another tray type is the ABS capped resin tray. To make this type of tray, a sheet of ABS / Acrylic plastic approx. 4mm to 6mm thick and slightly bigger than the area of the tray required is heated in a flat oven until it is pliable and soft and it is then placed on a vacuum mould in the shape of the tray desired. The edges of the sheet are then clamped to the edges of the mould or the structure of the moulding machine and a vacuum is created by sucking air through small holes in the tray mould. This has the effect of forcing the soft acrylic sheet onto the mould and cooling it down. When the sheet is cooled enough it sets hard and the clamps are removed and the vacuum turned off. The moulded tray shape is then placed in a metal support mould that has a shape that is exactly opposite to the shape of the tray to provide full support to all parts of the acrylic moulded sheet. The moulded tray in its metal support is then moved onto on a flat conveyor belt system. At this point a glue or adhesive is sprayed onto the underside of the tray to help the resin adhere to the plastic and the resin / ash mixture is poured into the void on the underside of the tray. This filled tray is then allowed to sit until the resin / ash mixture has hardened and the tray is then put through the final process step.

Another example is the gel coated resin tray. To make this, a mould is manufactured from aluminium or steel and a resin and filler mix is poured in and allowed to set. Once this is done, the set material removed from the mould, the material being set in a tray shape. The external surface of the material is then painted with epoxy type gel paint and allowed to set. Resin trays of this type are by far the most common available. However, they suffer from a number of problems. For example, once installed if a tray is not bedded in and supported properly its base can crack. Also, the colour of the tray is applied as a thin layer of paint, which, if scratched, is extremely difficult to repair.

As a development of the more conventional resin type trays, acrylic capped resin trays are becoming more popular. These combine the rigidity of the stone resin tray, but have the added advantage of being capped in acrylic. This produces a surface that is more resistant to impact and can be polished if scratched. They are however more costly to produce and as such are not available in the same number of sizes as stone resin trays.

Solid ceramic trays and the Aluminium / Steel trays are also available, but these tend to be made for industrial and public uses as they are the most durable but also the most expensive.

Summary of the Invention According to the present invention, there is provided a shower tray comprising an upper tray portion and a lattice support on a back of the upper tray portion, wherein the upper tray portion has a top layer that forms an external surface of the tray, and a base.

The top layer and the base of the upper tray portion may be injection moulded. Ideally the base provides structural strength. The top layer may have a colour that is temperature sensitive.

The top layer may be made of one or more of Styrene Acrylonitrile (SAN) / Polycarbonate (PC) / Acrylonitrile butadiene styrene (ABS), and preferably a combination of all of these, and / or the base may be made of one or more of. a polymer; plastic; rubber, wherein at least one of these may be recycled. The lattice may be in-filled with a filler material. The filler material may comprise one or more of. resin; plastic; rubber; ash. All or part of the filler material may be recycled.

One or more adjustable supports may be provided for adjusting the height of and/or for levelling the tray.

According to another aspect of the invention, there is provided a shower tray comprising an upper tray portion and a lattice support attached to a back of the upper tray portion, wherein a filler material in-fills all or part of the lattice support.

The upper tray portion may have a top layer that forms an external surface of the tray, and a base. The top layer and the base of the upper tray portion may be injection moulded. Ideally the base provides structural strength. The base may be made of one or more of: a polymer; plastic; rubber. The top layer may have a colour that is temperature sensitive.

The lattice may be bonded to the upper tray portion. The lattice support may be injection moulded onto the upper tray portion.

The lattice support and the upper tray portion may both be injection moulded. The lattice support and the upper tray portion may be injection moulded together using a single mould. Thus a one piece shower tray can be formed. Alternatively, the lattice support and the upper tray portion may be injection moulded in separate stages.

The lattice geometry may be square or rectangular or triangular or circular.

The lattice may extend across the whole of the upper tray portion to the edges of the tray.

A generator may be positioned in-line with a water inlet, wherein movement of water past the generator causes electricity generation. The generator may be connected to one or more lights and/or a temperature sensor.

One or more lights may be embedded within the tray. According to another aspect of the present invention, there is provided a method of making a shower tray comprising providing an upper tray portion and attaching a lattice support on its underside.

Brief Description of the Drawings

Various aspects of the invention will now be described by way of example only and with reference to the accompanying drawings, of which:

Figure 1 (a) shows a top view of a shower tray; Figure 1 (b) shows a top perspective view of the shower tray of Figure 1 (a);

Figure 1(c) shows a perspective view of the underside of the shower tray of Figure 1(a);

Figure 1 (d) shows two different geometries for the lattice shown on the underside of the shower tray in Figure 1(c); Figure 2 shows various views of another shower tray;

Figure 3 shows various views of yet another shower tray; Figure 4 shows a lattice of interconnecting blocks for use in a shower tray of the invention;

Figure 5 shows various steps in a method for making a shower tray that has a two layer top shell;

Figure 6(a) shows an injection mould machine for injection mounding of a part that has an internal void;

Figure 6(b) is a cross section through a shower tray in which selected spaces defined by the lattice are in-filled with a strengthening material; Figure 7 shows various steps in a method for making a shower tray that has a top shell that is back-filled with a filler material;

Figure 8 shows another method for making a shower tray that has a top shell that is back-filled with a filler material;

Figure 9(a) shows a cross section through a very thin shower tray made in accordance with the invention;

Figures 9(b) shows a photograph of the thin tray of Figure 9(a); Figure 10 is a plan view of a lattice for an underside of a show tray, the latter comprising multiple interlocking parts;

Figure 11 shows various views of a shower tray that is mounted directly onto a surface, such as a floor, using one or more levelling spacers; Figure 12 shows an off-floor mount shower tray that has a levelling system that has one or more height adjustable supports;

Figure 13 shows various views of another off-floor mount shower tray with a levelling system that has one or more height adjustable supports; and Figure 14 shows various views of another off-floor mount shower tray.

Detailed Description of the Drawings

Figure 1 shows a shower tray 1 that has a top or upper shell 2 made from an ABS sheet that is vacuum formed. The top shell 2 is substantially square in shape and has a hollow 8 formed in its upper face, as is commonplace, which is shaped to direct water to a drain hole 10. On the underside 4 of the top shell is a lattice type frame 6 that gives strength and durability, but with a significantly reduced weight relative to conventional trays. In Figure 1(c), the lattice 6 defines an array of squares 12, but other geometries are possible, for example circular 14 or triangular 16 arrangements, as shown in Figure 1(d). The lattice 6 can be made of any suitable material, such as any plastic, for example, polypropylene.

Although the tray 1 of Figure 1 is generally square shaped, it will be appreciated that any desired shape can be made, such as shown in Figures 2 and 3, where like parts are numbered the same as in Figure 1

The shower tray 1 can be formed using various techniques. In one case, the upper shell 2 is vacuum moulded and the lattice frame 6 is injection moulded onto the underside. In this case, the upper shell 2 is positioned in an injection moulding machine and the lattice formed directly onto its rear surface. In another example, the lattice frame 6 could be formed separately from the shell 2 and bonded onto it using a suitable bonding agent, for example an adhesive. Alternatively, the upper shell 2 may be injection moulded in a first process and then a second injection moulding process used to form the lattice. This can be done using multi stage injection moulding heads or two or more injection moulding machines. Alternatively, a two-stage process can be done in a single injection-moulding machine.

As yet another option, the shower tray 1 , including the upper shell 2 and the lattice 6 can be injection moulded using a single injection mould, so that whole tray can be made in a single process. In this case, the whole tray is typically made from a single material, for example ABS or polycarbonate, although a mould release agent or other additives may be added to help the mould come off and give a polished finish on the surface. This process results in a wholly integrally formed product. Blended polymers, for example, ABS/polycarbonate blends may also be employed in manufacture of the shower trays of the invention.

In all of the methods described above, the top shell may have two parts: a base section and a top layer. A structural plastic / polymer can be used to make the base part. This is designed for strength and durability and also stiffness to retain the flat shape and give more stability when a person is standing on the tray. The top layer is formed over the base part to provide the external surface of the tray. The top layer may be a plastic / polymer designed for surface properties such as brightness or scratch resistance or colourfastness etc but which might be quite pliable and "soft". It is also possible to use a semi-permeable top layer plastic such as HDPE if the base layer is completely water proof or vice versa. Using a double layered top shell, additives can be used in either the top or base layer to make the tray more forgiving of temperature and weight changes meaning a stronger overall tray and longer lasting structure. By working with multiple plastics and varied additives a better tray can be produced using better suited polymers.

Various materials can be used for the structural base part of the top shell. In a preferred embodiment, recycled plastic or rubber is used. This is possible, because the base is not seen by the purchaser / user, and so the lower grade finish that results from using such material is not visible. This provides significant cost and environmental benefits. Coloured or off white recycled (post consumer) / virgin (not post consumer) plastic can be used allowing the use of plastics that have superior structural properties but may be naturally coloured after manufacture. Lighter trays can be made by selecting a stronger base plastic that has no surface properties. As less of it is needed to provide the required strength, this would reduce cost, increase production speed, reduce warpage and benefit the environment by reducing the oil needed for production and also the weight of the product in transport and the fuel needed.

Various materials can be used for the top layer of the top shell. In a preferred embodiment, the material used for the top layer is any one or more of Styrene Acrylonitrile (SAN) / Polycarbonate (PC) / Acrylonitrile butadiene styrene (ABS). Additives can be included in the top layer to provide, for example, a non-slip upper surface or temperature sensitive indicators indicative of water temperature. Additives can also be added to help the final shape and improve the colour / light fastness. These are important for the shower tray because the surface must be perfectly smooth and flat on the outside rim to give a correct seal against the wall tiles and also the inside walls and slope must be perfect with no sagging so that the water runs away to the drain and does not pool inside the tray. Colourfastness is important because the tray must colour and shade match the tiles and the other ceramics in the bathroom and so must not fade over time. The additives must also give the surface strength and scratch / impact resistance to maintain the life of the tray and allow scrubbing and abrasive cleaning to treat mould and hard to remove deposits like scale and calcium.

Filler can be inserted into some or all of the spaces in the lattice. To do this, a pump activated filler with a control valve can be used the filler. Typically the filler is resin based. Pure resin can be used, but typically another material is used to bulk out and reduce the cost of the volume needed. Many materials can be used and examples would be paper, all plastics (except polystyrene), material such as cloth, fibreglass and glass, carbon fibre, stones, aggregate, concrete, wood, sawdust and sand. The most useful materials that can be used as the filler are, for example, a resin and ash mixture or a rubber and resin mixture. This latter option has the advantage of providing some elasticity and cushioning properties, which may prevent the surface cracking or wearing. Reaction promoters can be added to speed up setting or the resin and increase production speed and throughput. Examples of suitable promoters include cobalt salts / complexes, cobalt octoate and organic nitrogen compounds or potassium compounds. These improve the setting and curing time by producing free radicals at ambient and low temperatures in much greater numbers.

Fill and measurement of the resin / filler application may be by volumetric or sensor control - volumetric by pre set vessel or syringe type and then poured or pumped into the mould at set points within the structure or by weight or light sensor. The pump / valve is shut off when a pre set weight or increase in weight from the fill is reached or a light sensor at the side of the tray is set at a pre determined angle to the tray and when the tray is filled the light reflection angle changes - when the desired level is reached the reflection will hit a receptor that is light sensitive triggering the pump or valve to close. All or a selected few of the spaces can be filled to provide additional strength at points on the tray where there is extra weight or wear. In this way, a tray could be made with less plastic knowing that it was too weak in certain areas such as the middle where people stand, but then reinforced with resin underneath to prevent flexing and failure and give additional strength and weight.

There are a number of possible techniques for making a tray in accordance with the invention. In a first method, two separate machines are used side by side with a single screw feed. Alternatively, one machine may be used with a single screw feed and a change of mould after enough bases have been made. In either case, two moulds are used and the base is made using the first mould and the top layer is formed using a second mould. Where two machines are used, the second mould may be provided on the second machine and the base moved to fit onto it or where a single machine is used, the first mould is removed and replaced with the second mould. In any case, the base is fitted into the second mould and the top layer of plastic injected to fill the void between the inside of the second mould and the top surface of the base tray.

To avoid leaving a nipple or injection mark on the surface of the tray, the top layer is injected from the back side of the second mould. To do this, injection holes have to be provided on the base. To this end, the first mould has removable / screw in cylindrical sections at various points. When the first moulding is made, these cylinders are screwed in and sit proud of the rest of the mould half and touch the front half of the mould. This means that when the plastic is injected into the mould through the front or the back halves of the mould it leaves circular holes 401 in the surface of the base 402 where the cylinders were, as shown in Figure 4(a). These can then be used to inject the material for the top layer through, thereby to form the two layer top shell, as shown in Figure 4(b), where 404 is the top layer.

In another technique, a single metal mould fixed on one machine is used. After the base is made, the whole mould moves or rotates on the machine to then present the second injection holes to a second injection screw fitted to the same machine. The top injection is then made through the holes to create the top surface. The back of the mould is motorised to create the second injection void after the first injection stage. With this process, production is faster and more efficient, and because only one machine is powered up and heated rather than two, energy is reduced and wear and tear / maintenance is halved. In the methods described above, if the materials for the base and top layers used are very similar then it is preferable to inject the top layer onto the still warm or semi set base and cool them together, as doing so reduces the shrinkage and mould time and the part comes out with less internal stress. If the parts are very different materials or have a large difference in melting / setting temperature or shrinkage rate then the first plastic needs to have set before the second can be injected.

Yet another technique uses a single screw feed chamber that positions a first molton material inside a second material. In the present case, the base material, which is provided for strength would be the internal material, and the top later material, which determines the look and feel of the tray would be the second external material. The molten blob is injected into a single mould 50 and makes the tray in single step. This process is illustrated in Figure 5. In this case, the base material 51 , for example recycled plastic, is forced along the outer section of the screw 52 between its outer and inner walls, as shown in Figure 5 (a). Then the plastic for the top layer 53 begins its journey along the inner tube or screw to reach the gate at the front of the barrel, see Figure 5 (b). Both plastics reach the gate at the head of the screw, Figure 5 (c). The middle barrel and outer barrel points retract to create the "shot" that goes into the mould, as shown in Figure 5 (d). The gate on the barrel opens and forces the plastic into the mould together - with the virgin plastic 53 entering first. Recycled plastic 51 follows the virgin plastic 53 into the mould and sits in the middle of the "shot". In this case, even though the base material 51 may be made of recycled material the end product looks as if it is made entirely from virgin plastic whilst having a centre of recycled plastic. There are numerous benefits of this process. For example, there is less chance of warpage and the cost and complexity of multiple moulds, machines, screw feeds or moulds can be avoided.

In all of the methods described above, the material used for the base is selected for its strength. Since its external surface is completely covered by the top layer, its appearance does not matter. Because of this, the base may be made from materials such as plastic and rubber. In contrast the top layer has to be made from material with good quality external properties. As a specific example, the base may be made of recycled material and the top layer may be made from virgin plastic. This could give a tray that has recycled plastic in the base of approx. 5 kg and virgin plastic on the surface that is approx. 3.4 kg for a 900mm x 900mm quadrant shaped tray.

The weights of the top shell can be varied, as can the materials. For the base, one option is a blend of PP (polypropylene) + PC (polycarbonate) + ABS (Acrylonitrile butadiene styrene) + PVC (polyvinylchloride) and PS (polysulphones). For the top surface, a blend of SAN + PC + ABS and a plasticiser / rubberiser may be used to improve its flexibility, so that when this is applied and it contracts over the base it does not contract so strongly that it warps the tray. When it contracts it stretches to cover the surface. A benefit of using a rubber mix is that the hardness is reduced of the top surface making it more comfortable to stand on. Also, the material provides increased grip with reduced slippiness making it safer. The types of chemicals used for this surface plastic are commonly described as - TPO(thermoplastic olefin), TPV(thermoplastic vulcanizate), SBC(styrenic block copolymer blend), TPE or TPU(thermoplastic urethane elastomer), COPE(co-polyester elastomer), SEBS(styrene-ethylene/butylene-styrene block copolymer), POE(polyolefin elastomer), SBC(styrenic block copolymer),SBS(styrene-butadiene-styrene), SIS(styrene- isoprene-styrene), COPA( co-polyamide elastomer).

Another production method that could be used for making the tray is to co-inject plastic and nitrogen gas into a mould at the same time. This is illustrated in Figure 6. Plastic is fed into the mould to make the moulded tray part, in this case by a co-injection process that uses two injection screws 60. After the mould has made the part, a section within the mould is retracted whilst the main outer parts of the mould stay in place and the seal from the outside atmosphere is maintained. This creates a small void space in the enclosed mould. An injector lance 61 is fed into the void space by a motor (not shown) and when positioned within the plastic of the base section of the part nitrogen gas or another gas is forced into the mould. This has the effect of "blowing up" the plastic section like a balloon and creating a gas space 62 the same shape as the void created by the retraction of the mould part. When the plastic reaches the new void limits, it stops expanding. This void space volume can be calculated in advance and the exact amount of gas equal to this new volume injected or an excess of gas can be added to create a space with higher pressure and therefore more resistance to shock or heavy weight bearing. This can have the effect of producing a stronger tray and also one with more cushioning effect for the user. If a further step of filling the underside voids with resin is to be done then it also benefits the cost of producing the tray and the manufacturing time by reducing the amount resin needed and also the setting time of this resin.

Once the top shell is prepared, the lattice is attached as described previously either as a separate step of as part of the same injection process used to form the top shell. If desired the spaces in the lattice may be infilled with filler, such as a resin. Normally the resins used for this type of process are Unsaturated Polyester resins with a small ammount of styrene. The resin is polymerised by use of free radicals from metal salts of carboxylic acids and peroxides. Accelerators and promotors from cobalt complexes, cobalt octoate and organic nitrogen compounds improve the setting and curing time by producing the required free radicals at ambient and low temperatures in much greater numbers. Figure 6(b) shows an example of a tray that has a double layer top shell 64 and a lattice 66 that has selected spaces 68 in-filled.

To in-fill the lattice, the tray 70 is removed from the moulding machine 71 and taken to a filling machine 72, as shown in Figure 7. In this case, the thickness of the top shell has to be sufficient to support the weight of the filler material without warping or distorting. To achieve this, the wall thickness would have to be around 8 to 10mm. The tray is filled to the desired level (for example to completely fill the underside of the tray) whilst being vibrated on a vibrating pad 73 or filled and then placed on a vibrating pad. This can either be part of a long conveyor system straight from the filling station or a separate unit. The vibration removes air pockets and ensure that the resin reaches every point and has good contact with the inside surface of the tray and provides a perfectly flat surface at the base (top as it is upside down) of the tray so that no grinding is required as a secondary step when the resin is set. The trays would then be placed or continue on the conveyor to a drying tunnel 74 that heats and sets the resin 75. The dried and finished tray appears from the end of the tunnel. The tray is polished and then placed in a box ready for shipment.

The whole process can be automated by using robotic arms to remove the tray from the injection mould machine and place this on a moving conveyor which then moves to the resin filling point. The resin would be located in a tank or vessel above or beside the conveyor and be released or pumped into the mould. One or more sensors could be used to detect the resin reaching the top of the mould by light refraction / back pressure or by pre set weight (having weight sensors under the conveyor) - this can also be done by a volumetric calculation and the resin delivered by pre set syringe / vessel type arrangement. The conveyor then moves on and enters the heat tunnel which can be speed controlled or length / temperature controlled to a set speed and then automatically packed and stacked at the end when cooled.

Figure 8 shows another method for making shower trays. In this case, rather than using a standard injection moulding barrel, which is horizontally positioned, the injection barrel 80 is located vertically above the mould 81. Plastic is inserted into the barrel 80 as normal. Friction and pressure increases as the plastic progresses along the barrel and with some additional heat from outside the barrel with jacket heaters the plastic melts and is under great pressure when it reaches the thin end of the screw. At the end of the barrel 80 is a gate valve which leads to the mould. When the gate between the barrel and the mould is opened this allows the plastic to flow into the mould and take up the shape of the void within the mould 81. This injection process can be used to form the top and base layers, as well as the lattice. The tray 82 still in its mould 81 is then moved along a conveyor belt to a filling location 83 where it is filled with resin. Because the moulded plastic is not removed from the mould, sufficient support is provided to allow the thickness to be relatively low, for example 3 to 4mm.

Once filled, the tray 82 is moved onto a vibrating table. As before, this can either be part of a long conveyor system straight from the filling station or a separate unit. The vibrations cause any air pockets to be removed and ensure that the resin reaches every point of the inside of the tray and provides a perfectly flat surface at the base of the tray so that no grinding is required as a secondary step when the resin is set. The trays are then placed or continue on the conveyor to a drying tunnel 84 that heats and sets the resin more quickly under that action of a resin setting chemical promoter. The dried and finished tray emerges from the end of the tunnel. The tray is polished and placed in a box ready for shipment.

This production process is very fast as the bottom half of the mould 81 that holds the tray 82 can be made over and over again with only one top half 85 needed attached to the injection barrel. The bottom parts of the mould 81 that holds the shape of the tray are placed in a line before the barrel and are conveyed to the barrel one after another so when the front mould is filled with the tray skin and moves to the filling point, the next mould is placed under the barrel and the process is repeated. When the tray is finished and the mould no longer needed it is returned for re-use manually or automatically by conveyor.

For a shower tray to be sold as a certified disabled / easy access tray for wheelchair users and also for the elderly / infirm, it has to have a frame that is only 25mm high (or less), as shown in Figure 9(a). To allow the manufacture of a thin, but strong tray, the upper tray is formed of two layers, as described above, with a lattice support on its back surface. In this case, the lattice extends across the whole of the under surface of the tray to provide additional strength, as shown in Figure 9(b). The edges of the tray are also strengthened by increasing the thickness of the outer top surface and also the vertical tray wall beyond the standard thickness from maybe 5mm to 10 or 12mm or any suitable thickness though.

Resin may be added to the outer rim of the tray where the tray is flat before it drops down to the standing area and a non-slip material is added to the surface. In addition, a hard resin compound may be used to in-fill the underside of the tray (not shown) and all the squares / circles etc making up the lattice support. Reaction promoters can be used to speed up setting or the resin and increase production speed and throughput. Examples of suitable promoters include cobalt salts / complexes, cobalt octoate and organic nitrogen compounds or potassium compounds. These improve the setting and curing time by producing free radicals at ambient and low temperatures in much greater numbers. Using a resin as a solid fill avoids the problem of uneven distribution of weight causing cracks and marks and injection moulded caps to get the surfaces and edges to line up and allow the tray to sit flat and the water to run away effectively.

Where the lattice 6 is made separately and attached to the top shell, it may be formed as a single unit or may be built up from multiple inter connecting blocks 18 (as shown schematically in Figure 10). An advantage of using interconnecting blocks 18 is that only two or three plastic moulds would be needed for all design options rather than a new mould for each design and shape. In practice, this results in significant savings in terms of both time and resources. All but one of the blocks shown in Figure 10 are generally square in shape and so can form a generally square or rectangular shaped lattice support. They interlock by means of corresponding slots 19 and projections 20 of adjacent blocks 18. Appropriately curved blocks 21 (one example shown in Figure 10) can be provided to correspond to the shape of a tray, see for example Figure 2. The blocks may be formed to interlock ("clip") securely together to form the lattice 6. If desired they may be bonded together for additional strength and rigidity.

A lighting system may be added to the tray, for example light emitting diodes or any other suitable light source of any colour or size. The lights may be moulded into the base and powered by a small turbine fitted in line to the cold or hot water feed pipe leading to the shower valve. When the shower is turned on rotation of the turbine blades causes generation of a small amount of electricity, sufficient to turn the lights on. The lights can be used for illumination or can be arranged for use as a temperature gauge. In the latter case, a temperature sensor would be provided for sensing the temperature of the water. The sensor is linked to a controller that controls the lights depending on the sensed temperature. The sensor is linked to a controller that controls the lights depending on the sensed temperature. This would have the safety benefit of warning the user of the shower of any sudden changes in the temperature of the water travelling to the shower head and enable the user to remove themselves from the shower stream before the varied temperature water reached them.

Figure 11 shows a shower tray 110 that is fitted with a generator 111 that is connected in-line with the water supply (not shown) for the shower. Connected to the generator 111 is a controller 112 that is connected to a temperature sensor 113 and a plurality of lights 114 arranged in a column. The lights 114 may be of any colour but in a preferred embodiment the lower third are blue to indicate that the water is cold; the middle third are green to indicate that the water is at a comfortable temperature and the top third are red to indicate that the water is hot. When the water is turned on the generator 111 generates power, which powers up the controller 112, which in turn activates the temperature sensor 113. The sensor 113 sends information on the temperature to the controller 112 which causes the appropriate light 114 to be illuminated. In this way a visible indication of the water temperature is automatically provided. The lights can be in any colour, shape or pattern and can also be controlled to flash in sequence or when a sudden change in temperature is detected. The temperature lights can also be placed within the tray, on the tray surface or on the wall or shower column next to the tray. To simplify the shower tray installation process, a number of levelling techniques are proposed. Figure 12a shows the underside of a shower tray 1 of the invention, Figure 11b shows the tray 1 in plan view and Figure 12c a schematic cross section along the line BB of Figure 12b. In this example the tray 1 is secured directly to the floor using levelling spacers 22, These comprise thin discs 24 of plastic of any suitable shape and/or size that in this example have an adhesive surface 25 on one side, this initially being protected by a piece of plastic coated paper until needed. Each disc 24 may be 1 to 4 mm thick. As shown in Figure 12c the discs 24 may be secured to the floor 26 by means of a screw fixing 28. Alternatively an adhesive may be employed.

Fitting the tray in place may be carried out as follows. When the tray 1 is placed in position on the floor 26, the installer takes an initial reading of the level of the tray and then attaches discs 24 on the underside of the tray 1 at points where the floor 26 is low until the tray 1 is supported at all necessary points. This is achieved by means of sticking the discs 24 to the tray by removing the plastic paper and exposing the adhesive surface 25. If multiple discs were needed to achieve a desired thickness the installer would attach the discs to each other first to build up a taller block.

Figure 13 shows an alternative arrangement for mounting on the floor 26. Figure 13a shows the underside of a shower tray 1 of the invention fitted with height adjustable supports 30. Figure 13b shows the same tray 1 in plan view and Figure 13c shows in elevation a detail of the tray 1 with two of the height adjustable supports 30 fitted. In this case, height adjustable supports 30, typically made of plastic, are used.

The tray of Figure 13 is an "off-floor" mount shower tray that has a high level tray that would be used with a front panel (not shown). This configuration is used where the installer cannot get easily under the floor to run the pipework for the tray 1 or the customer wants a higher height tray for aesthetic or practical reasons. For this, the tray is installed on levelling / adjustable legs and the installer puts a covering front panel below the tray front edge to cover the gap between the floor and the underside of the tray.

The height adjustable supports 30 are sized to fit into gaps in the lattice support 6 in this example. The supports 30 are tubular and have a top cap 32 and a lower mounting foot 34 that is screw fitted into the cap 32. This gives a height adjustable support or leg that fits inside the space between the plastic grids. Specific, predetermined spaces in the lattice may be marked and strengthened for receiving one of the height adjustable supports 30. Alternatively, where the lattice 6 and top shell 2 are strong enough, any spaces may be used.

On the underside of the moulding, at least one fixing element 36 is provided to receive a top cap 32 (a "can") and fix it to the underside of the tray 1 so it does not move once it is installed. Ideally, a fixing element 36 is provided at every corner of the tray. Once the lower mounting feet 34 have been fitted and adjusted to level the tray 1 , the tray is secured to the floor 26, for example by using an adhesive and paper peel off system similar to that described above. Alternatively, the supports 30 may merely be glued to the floor. A typical range of adjustment for the height adjustable supports 30 of Figure 6 may be of the order of 80-115mm.

Figure 14 shows another off-floor mount shower tray that has a high level tray 1 that would be used with a front panel (not shown). Figure 14a shows a plan view of the underside, Figure 14b an end elevation and Figure 14c shows in perspective a detail of the height adjustable supports 30.

The height adjustable supports 30 may be constructed out of plastic or metal or a combination of both. The top cap 32 or section of the supports 30 fixes onto the lattice 6 at the corners / meet points of each square / triangle etc. in this example using the pre-applied adhesive technique described above for the discs 24 of Figure 12. It will be appreciated that the top caps may be attached by other means, for example by a separately supplied adhesive, by clips or other mechanical fixings such as screws secured to an appropriately formed portion of the tray 1 (top shell 2 or lattice 6).

Outside the top caps 32 the lower mounting feet 34 are fitted, either by being screwed in or fixed in by means of receiving fins or clips on the inside of the top caps 32. The installer adjusts the height of the supports 30 (legs) until the tray is level and of the correct overall height to receive the front panel. This is normally around 100mm but it can vary according to the design. As shown in Figure 14b the length of the supports 30 is sufficient to allow routing of the pipe connection 35 above the floor 26. Another method is illustrated in Figure 15. This uses height adjustable supports 30, similar to those described above for Figure 13, for the four outside levelling points and a single / or multiple (for bigger trays) adjustable large support 38 leg in the middle of the tray. This has the benefit of spreading the weight over a wider area and also is simpler for the installer as only one support or leg requires adjustment in the (difficult to reach) centre underneath of the tray when levelling. As shown in the perspective view of Figure 15a the underside of the shower tray 1 has four height adjustable supports 30 around its periphery. In the centre a single large support leg 38 is fitted. This has an adjustable (screw threaded) large foot 40 which screws in to a large pedestal 42 which spreads the load across the centre portion of the tray and is fitted with reinforcing fins 44 for additional strength and rigidity (see the cross section elevation of Figure 15b).

To help the installation, the shower tray may be accompanied by with an exact paper profile of the underside shape and design of the tray as if it were traced out or done via a brass rubbing type process. On this diagram the best places to place discs or supports (legs) and/ or the location of pre-strengthened points on the tray where the supports or levelling discs should go are marked. The installer uses the diagram by taping / putting this on the floor where the tray will sit and uses it to mark the points on the floor where they need to place / screw the supports, discs or legs to the floor. The installer levels the supports in position using the diagram and a spirit level before the tray is put down and fixed into position. This can be easier than trying to level the supports or legs when the tray is on top. This is particularly the case with regard to reaching all the adjustment points underneath the tray from the front.

A skilled person will appreciate that variations of the disclosed arrangements are possible without departing from the invention. For example it will be appreciated that the height adjustable supports 30 of Figures 13, 14 and 15 can also be used with an "on-floor" shower tray arrangement such as that shown in Figure 12. The height adjustable supports 30 replace the discs 24 of Figure 12 but are shorter in length to allow the tray 1 to rest on the floor 20. For use with a typical on-floor tray the range of adjustment would typically be 25mm to 40mm. Also grooves may be incorporated into the plastic under the tray top shell to leave space for routing the cold water pipes supplying the shower. The cold water flowing through the pipes can then be pre-heated by the hot water from the shower running across the tray that has already been used by the person showering. This heat exchange can allow the hot water volume / flow to be reduced and save energy. In a further variation, wires or capillary pipes can be built into the top surface to recover the heat from the shower water to preheat the cold water going to the shower and save energy. Accordingly, the above description of specific embodiments is made by way of example only and not for the purposes of limitations. It will be clear to the skilled person that minor modifications may be made without significant changes to the operation described.

Claims

1. A shower tray comprising an upper tray portion and a lattice support on a back of the upper tray portion, wherein the upper tray portion has a top layer that forms an external surface of the tray, and a base.

2. A shower tray as claimed in claim 1 wherein the top layer and the base of the upper tray portion are injection moulded.

3. A shower tray as claimed in claim 1 or claim 2 wherein the base of the upper tray portion provides structural strength.

4. A shower tray as claimed in any of the preceding claims wherein the base is made of one or more of: a polymer; plastic; rubber.

5. A shower tray as claimed in any of the preceding claims wherein the lattice is in-filled with a filler material.

6. A shower tray as claimed in claim 5 wherein the filler material comprises one or more of: resin; plastic; rubber; ash.

7. A shower tray as claimed in claim 5 or claim 6 wherein all or part of the filler material is recycled.

8. A shower tray as claimed in any of the preceding claims comprising one or more adjustable supports for adjusting the height of and/or for levelling the tray.

9. A shower tray as claimed in any of the preceding claims wherein the top layer is made of one or more of Styrene Acrylonitrile (SAN) / Polycarbonate (PC) / Acrylonitrile butadiene styrene (ABS)₁ and preferably a combination of all of these.

10. A shower tray as claimed in any of the preceding claims wherein the top layer is has a colour that is temperature sensitive.

11. A shower tray comprising an upper tray portion and a lattice support attached to a back of the upper tray portion, wherein a filler material in-fills all or part of the lattice support.

12. A shower tray as claimed in claim 11 wherein the upper tray portion has a top layer that forms an external surface of the tray, and a base.

13. A shower tray as claimed in claim 12 wherein the top layer and the base of the upper tray portion are injection moulded.

14. A shower tray as claimed in claim 12 and 13 wherein the base of the upper tray portion provides structural strength.

15. A shower tray as claimed in any of claims 11 to 14 wherein the base is made of one or more of: a polymer; plastic; rubber.

16. A shower tray as claimed in any of claims 11 to 15 wherein the top layer is made of one or more of Styrene Acrylonitrile (SAN) / Polycarbonate (PC) / Acrylonitrile butadiene styrene (ABS), and preferably a combination of all of these.

17. A shower tray as claimed in any of the preceding claims, wherein the lattice support is bonded or injection moulded to the upper tray portion.

18. A shower tray as claimed in any of the preceding claims, wherein the lattice extends across the whole of the upper tray portion to the edges of the tray.

19. A shower tray as claimed in any of the preceding claims, wherein the lattice is bonded or injection moulded to the upper tray portion.

20. A shower tray as claimed in any of the preceding claims, wherein the lattice support and the upper tray portion are both injection moulded.

21. A shower tray as claimed in claim 18, wherein the lattice support and the upper tray portion are injection moulded together using a single mould.

22. A shower tray as claimed in claim 21 , wherein the lattice support and the upper tray portion are injection moulded in separate stages.

23. A shower tray as claimed in any of the preceding claims, wherein the lattice geometry is square or rectangular or triangular or circular.

24. A shower tray as claimed in any of the preceding claims made from ABS or polycarbonate.

25. A shower tray as claimed in any of the preceding claims comprising a generator positioned in-line with a water inlet, wherein movement of water past the generator causes electricity generation.

26. A shower tray as claimed in claim 25 wherein the generator is connected to one or more lights and/or a temperature sensor.

27. A shower tray as claimed in any of the preceding claims wherein one or more lights are embedded within the tray.

28. A method of making a shower tray, the method comprising forming an upper tray portion that defines an external surface of the tray and a rear cavity, the upper tray portion having at least two layers; and attaching a lattice support on an underside of the upper tray portion within the rear cavity.

29. A method as claimed in claim 28 comprising in-filling one or more gaps defined by the lattice.

30. A method claimed in claim 28 or claim 29 wherein the top layer is made of one or more of Styrene Acrylonitrile (SAN) / Polycarbonate (PC) / Acrylonitrile butadiene styrene (ABS), and preferably a combination of all of these, and / or the base is made of one or more of: a polymer; plastic; rubber, where one or more of these may be recycled.

31. A method of making a shower tray, the method comprising forming an upper tray portion that defines an external surface of the tray and a rear cavity; attaching a lattice support on an underside of the upper tray portion within the rear cavity and in-filling one or more spaces defined by the lattice with a filler material.

32. A method as claimed in any of claims 28 to 31 comprising injection moulding the upper tray.

33. A method as claim in claim 32 comprising injection moulding the upper tray using at least one mould part; retaining the upper tray in the mould part and infilling the lattice whilst the upper tray is retained within the mould.