The present invention relates to air mats, in particular air mats containing down or synthetic insulated filling.

Air mats containing down or synthetic insulated filling are known, examples of such mats are described in US Patent Publication No. 2005/0188466. These down or synthetic insulated filling containing air mats had as their object reducing heat loss through convection and radiation during use.

Air mats are generally comprised of at least one air chamber. The chamber is filled with air when in use . Heat loss through convection occurs when air is free to circulate in a chamber. It was envisaged that presence of down or synthetic insulated filling in the air chambers of air mats would reduce free air circulation and as a result reduce heat loss through convection.

The presence of down or synthetic insulated filling in a mat also affects heat loss by radiation: by putting solid objects between the heat source and the cold environment this heat loss is reduced. Heat loss by radiation is also affected by the relative sizes of the solid surfaces which the radiation hits: infrared wavelengths and those which transfer heat interact most with objects of similar size . Down and synthetic insulated filling diameters closely match the wavelengths of infrared light.

However, in the existing down or synthetic insulated filling containing air mats a common problem is movement of the down or synthetic insulated filling within the air chambers, for example the down or synthetic insulated filling is known to move during inflation and use. This results in much or all of the down or synthetic insulated filling being concentrated in one area of the chamber leaving other areas unfilled. Clearly in the areas of the chamber in which there is little, or no, down or synthetic insulated filling the air is free to circulate meaning that there is little, or no, reduction in heat loss through convection. Furthermore in the areas of the chamber in which there is little, or no, down or synthetic insulated filling there is little, or no, reduction in heat loss by radiation. There is therefore still a need for an air mat which reduces heat loss through convection and radiation.

The present invention relates to an air mat comprising an air chamber containing down or a synthetic insulated filling, the air chamber is provided with means to reduce movement of the down or synthetic insulated filling within the air chamber.

Reducing movement, or put another way increasing stability, of the down or synthetic insulated filling leads to increase in thermal resistance and reduced heat loss due to convection and radiation. These improved thermal properties also enable reduction in mass of insulation (down or synthetic insulated filling) required in the air mat. This in turn allows the total mass and size of a back pack in/on which the mat is to be carried to be reduced. The air chamber preferably extends along the length of the air mat. The air chamber preferably has a length, a width and a depth. The length of the air chamber may be coextensive with the length of the air mat.

The means to reduce movement of the down or synthetic insulated filling may be a baffle positioned inside the air chamber.

The baffle may be elongate. The baffle may extend from one part of the inside of the air chamber to another part of the inside of the air chamber. The baffle may extend along all or part of the length of the air chamber, or along all of part of the width of the air chamber, or along all or part of the depth of the air chamber or in a diagonal across all or part of the air chamber.

The baffle typically extends along all or part of the length of the air chamber.

The baffle may extend along all of the length of the air chamber.

The baffle may have a first end and a second end and the first and second ends are secured to the inside of the air chamber. The baffle may have a first end secured to a first end of the air chamber and a second end secured to a second end of the chamber.

The first and second ends of the baffle may be secured to the air chamber by any suitable means such as high frequency welding, adhesive, bonding, laminating or sewing.

The baffle is preferably twisted along its length. The baffle may have between one and 100 twists along its length. The baffle may have between 1 and 90, or 1 and 80, or 1 and 75, or 1 and 70, or 1 and 60, or 1 and 55, or 1 and 50, or 1 and 40, or 1 and 35, or 1 and 30, or 1 and 25, or 1 and 20, or 1 and 15, or 1 and 10, or 2 and 8, or 3 and 7, or 4 and 6, or 5 twists along its length.

In this way, a spiral with a repeat unit of length from 5 cm to 200 cm is created. The spiral may more preferably have a repeat unit of length between 5cm and 150cm, or between 5cm and 125cm, or between 5cm and 100cm, or between 8cm and 75cm, or between 10 cm and 50cm, more preferably yet between 25cm and 40cm.

The twisting of the baffle creates a helical shape of varying pitch and number of nodes. The helical shape created reduces air flow and movement of the down or synthetic insulated filler within the air chamber.

The baffle may be a strip of any suitable material.

The strip may have a width of 3 to 10cm measured when the strip is planar. The width may be 3 to 8cm, or 3 to 6cm, or 3 to 4cm, for example 3.5cm measured when the strip is planar.

The strip may have a length of 80 cm to 220 cm measured when the strip is planar. The length may be 100cm to 200cm, or 120cm to 180cm, or 140cm to 160cm measured when the strip is planar.

The baffle may be a strip of a suitable fabric. The baffle may comprise any fabric which adheres to down and/or synthetic insulated filler. The fabric could be made from a natural fibre. More preferably the fabric is made from a synthetic fibre, for example nylon, polyester or polypropylene.

The fabric could be wadding, nonwoven stripping, woven or knitted fabric. More preferably the fabric is spunbond-meltblown-spunbond, spunbond-meltblown- meltblown-spunbond, or another combination of spunbond and meltblown fibres, or a knitted or mesh fabric.

The fibre or fabric could be coated or treated to increase or decrease hydrophobicity, affect surface tension, or could be metallised to change radiative properties.

The fabric and/or the coating or lamination used can assist in reducing movement of the down or synthetic insulated filler by causing at least a portion of the down or filler to adhere to it. The air mat may comprise more than one air chamber. The air chambers may be secured to each other by any suitable means such as welding or adhesive. Alternatively the air mat may be of unitary construction and comprising more than one air chamber. One or more of the air chambers may be provided with means to reduce movement of the down or synthetic insulated filling within the air chamber according to the invention.

One or more of the air chambers may be provided with more than one means to reduce movement of the down or synthetic insulated filling according to the invention.

There may be 4 to 10 air chambers, for example 5 to 9, or 6 to 9, or 7 to 9, or 8 air chambers. The air chambers may have a width of from 5 to 10 cm, for example 5 to 9 cm or 6 to 8 cm, or 6cm or 7cm or 8 cm.

The depth of the air chambers may be from 2 to 7cm, for example 3 to 6cm, or 3 to 5cm or 4 cm. The means to reduce movement of the down or synthetic insulated filling within the air chamber may be body mapped within one or more of the air chambers to increase or decrease the degree of insulation in parts of the mat.

The air mat may be provided with an inflation chamber in communication with an air inlet and one or more of the air chambers. The inflation chamber and air chamber may be separated by a wall. The wall may comprise an aperture allowing communication between the inflation chamber and the air chamber. The aperture may be sized to allow passage of air into the air chamber at a rate that is less than that of passage of air in through a valve . The aperture may be provided with a mesh or foam covering to further reduce rate of passage of air into the air chamber.

A valve may be provided to allow air into the inflation chamber. The valve may be closable .

The air mat may be made from any suitable synthetic fabric, for example Nylon or polyester. The fabric may be coated or laminated with thermoplastic polyurethane (TPU) or polyurethane (PU).

The length of the air mat may be from 100 cm to 250 cm, more preferably from 170 to 200 cm.

The width of the air mat may be from 50 to 200 cm, more preferably from 54 to 120 cm. The thickness of the air mat may be from 5 to 30 cm, or 5 to 25cm, or 5 to 20cm, or 5 to 15cm, more preferably 7 to 9 cm.

The synthetic insulated filling may be a loose filing such as fibre balls, staple fibres, nonwoven fibre strips, a blend or mixture of the aforementioned.

The down should preferably be washed and cleaned according to methods known by someone skilled in the art.

Typically the fill power of the washed down when measured by IDFB testing following steam conditioning should be in excess of 300 cubic inches per ounce, more preferably in excess of 500 cubic inches per ounce, and more preferably yet equal to or in excess of 700 cubic inches per ounce.

The down may be down feathers, flight feathers, or a mixture thereof. Down may be of goose, duck or eider origin. Down: flight feather ratios of 10: 90 to 100: 0 may be used, or 10: 90 to 97: 3, or 30: 70 to 95 : 5, or 50: 50 to 94:6, but most preferably from 80:20 to 93 : 7 should be used.

The down or synthetic insulated filling may be coated or otherwise, for example with the intention of increasing water resistance, reduce static build-up, or to increase antibacterial properties. Insulation fill weight should be from 10 grams to 500 grams, more preferably from 60 grams to 300 grams, and more preferably yet from 100 to 150 gramsin a whole mat of 'regular' dimensions: i.e. a mat 185 cm long, 54 cm wide, 7 cm thick.

The air mat may be provided with one or more valves for allowing air into and out of the or each chamber.

Experimental

Experiments on an air sleeping mat according to the invention were carried out using a tog testing rig according to a modified version of Standard BS4745 : 2005 ("Determination of the thermal resistance of textiles — Two-plate method: fixed pressure procedure, two-plate method: fixed opening procedure, and single-plate method") . Using the method above the result was:

Down mat: 8.8 togs ( 1 tog = 0.1 m ² K W ^"1 ) The mat according to the invention that was tested used 120 g of down in a regular ( 185x54x7 cm) mat. In the mat tested the baffles were elongate baffles running along the length of the inside of each air chamber.

This compares very favourably with an existing commercially available down filled sleeping mat, Downmat 7M from Exped AG which has R value 5.9 for same approximate thickness as mat of the invention that was tested and uses 170 g of down. Because the mat of the invention used so much less down than the commercially available mat it is clear that the mat of the invention will be warmer than the commercially available mat it was compared with. An embodiment of the invention will now be described by reference to the figures in which:

Figure l a and 1 b show top and bottom views respectively of an air mat according to the invention;

Figure 2 shows an expanded bottom view of an air mat as shown in figure lb; Figure 2a shows expanded detail of various features; Figure 3 shows an expanded bottom view of an air mat as shown in figure lb; Figure 3a shows expanded detail of various features;

Figure 4 shows a cut away bottom view of an air mat s shown in the earlier figures;

Figures 4a and 4b show expanded detail of various features;

Figure 5 shows a cut away bottom view of an air mat s shown in the earlier figures; Figure 5a shows expanded detail of various features;

Figure 6 shows a cut away bottom view of an air mat s shown in the earlier figures; and Figure 6a shows expanded detail of various features;

In figure la a top view of an air mat 1 according to the invention is provided and in figure lb a bottom view of the air mat 1 is provided. The air mat is made from Nylon or polyester and coated or laminated with TPU or PU. The air mat 1 comprises eight elongate air chambers 2 separated by internal walls indicated at 3. The air chambers 2 contain down or synthetic insulated filling, not shown. A valve 5 is provided through which air can be introduced to the air chambers 2 or allowed to escape from the chambers. The valve 5 is positioned in an inflation chamber 6 which runs across the width of the air mat 1 and into which the air flows before entering or exiting the air chambers 2. The air chambers 2 are positioned transvers to and extending from the insulation chamber 6.

The inflation chamber 6 and valve 5 are provided at the foot end of the air mat.

Figure 2 shows a bottom view of an air mat as described in figure lb above . Figure 2a shows the inside of the air mat 1 and in particular shows the insulation chamber 6 and its interaction with the air chambers 2. The insulation chamber 6 is formed at an end of the air mat 1 by a wall 7 extending across the width of the air mat 1. The wall 7 is secured all around its edges to the inside of the air mat. The wall 7 is made from a thermoplastic polyurethane film to which a 5 mm thick foam 8 is bonded. The foam 8 is bonded to the wall 7 facing into the inflation chamber 6. The wall 7 is provided with four holes 9 of 5mm diameter leading into each air chamber 2. The foam 8 is not provided with any holes. The purpose of the inflation chamber 6 is to prevent the influx of air causing extensive movement of the down or synthetic insulated filler. Air must enter the inflation chamber 6 and then pass through the foam 8 before entering the air chambers 2 through the holes 9 in the wall 7. Figure 2a also shows the walls 3 separating the air chambers 2 from each other. The walls 3 are formed from thermoplastic polyurethane film and have a depth of 4cm. The walls 3 are secured to the wall 7 at one end and are secured to inner top and bottom surfaces of the air mat along their length. Figure 3 shows a bottom view of an air mat as described in figure lb above . Figure 3a shows the inside of the air mat 1 and in particular shows the foam block 4 and its interaction with the walls 3 forming chambers 2. The foam block 4 is formed at an end of the air mat 1 extending across the width of the air mat 1 . The foam block 4 is secured around its edges to the inside of the air mat. The foam block 4 allows air to flow from one air chamber 2 to another but controls this air flow so that shift of the down or synthetic insulated filler is reduced.

The walls 3 between air chambers 2 are received by the foam block and secured in place.

Figure 4 shows the provision of elongate baffles in the form of strips of fabric 10 extending along the length of the inside of each of the air chambers 2. The fabric is a 70 g m ^"2 nylon mesh.

Each strip of fabric 10 is twisted five times along its length, as shown in figure 4a.

Each strip of fabric 10 has a width of 3.5cm and for an air mat 1 of length 185 cm each strip of fabric 10 has a length when in planar form of 185 minus the width of the foam block used to stop down migration, as shown in figure 4b.

Each strip of fabric 10 is secured at one end 10a to the foam block 4 and at the other end 10b to the wall 7 of the insulation chamber 6. The strip 10 is not secured to the air chamber at any other point.

The presence of the fabric strip and in addition its shape and the material from which it is made assist in reducing the movement of the down or synthetic insulated filling within the air chambers 2. Figure 5 shows a cut away bottom view of an air mat as described in figure 4 above.

Figure 5a shows the inside of the air mat 1 and in particular shows the wall 7 of the insulation chamber 6 and its interaction with the strips of fabric 10. The strips of fabric 10 are secured to the wall 7 by means of an additional piece of TPU 1 1. The strips of fabric 10 are directly bonded to a strip of TPU 1 1 , and then that TPU strip 1 1 is bonded to wall 7. In effect, the TPU strip is used like double-sided tape to hold the fabric 10 to wall 7. The ends 10b of the strips of fabric 10 are secured to the wall 7 such that the ends of the strips are transverse to the longitudinal axis of the wall. Figure 6 shows a cut away bottom view of an air mat as described in figure 4 above.

Figure 6a shows the inside of the air mat 1 and in particular shows the foam block 4 and its interaction with the strips of fabric 10. The ends 10a of the strips of fabric 10 are secured on one side to the foam block 4 by means of an additional piece of TPU 12. The strips of fabric 10 are directly bonded to a strip of TPU 1 1 , and then that TPU strip 1 1 is bonded to block 4. In effect, the TPU strip is used like double-sided tape to hold the fabric 10 to block 4. The ends 10a of the strips of fabric 10 are secured to the foam block such that the ends of the strips are parallel to the longitudinal axis of the block.

In use the air mat 1 is rolled out and inflated by inlet of air through valve 5 into the inflation chamber 6. The air then moves steadily into the air chambers 2 through the foam 8 and apertures 9 inflating the air chambers without causing shift of the down or synthetic insulated filling within the air chambers.

The mat is then slept on before being deflated by forcing air out of the air chambers 2 through apertures 9, foam 8 and valve 5 in the insulation chamber 6. The mat can then be rolled for transportation or storage . The presence of the strips of fabric 10 within the air chambers 2, together with one or both of their shape and the material they are made from, ensure that during inflation, use and deflation of the air mat 1 the down or synthetic insulated filling remains distributed throughout the air chamber 2 and does not end up concentrated in one area. This reduced movement of the down or synthetic insulated filling improves the insulation properties of the mat, particularly reducing heat loss through convection.