GB2375043A - Inflatable article - Google Patents

Abstract

An inflatable cushion is formed from two layers of material that are seam-welded together. The seam is provided with a local weakness such that upon a predetermined excess internal pressure of the cushion over the ambient pressure, the cushion deflates in a controlled manner. The cushion may be divided into two communicating compartments, and finds particular application as a neck support or as foot-exercising cushion for use in pressurised aircraft.

Description

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Inflatable Article This invention relates to an inflatable article, and finds particular, though not exclusive, application to an inflatable cushion.

Inflatable articles find use in a variety of applications, and the present invention is particularly concerned with articles that are to be used in a pressurised environment, such as that found in the cabin of an aircraft. Although, for convenience, reference will be made specifically to the article being a cushion, it will be appreciated that the invention has broader applications.

When travelling in an aircraft, an inflatable cushion is often used, for example to provide support for the neck whilst a passenger is reading, or sleeping, as a back support, or as a foot support. Typically, such cushions are formed from two layers of material that are welded together at least around their periphery, and one of the layers is provided with an inflating tube so that the cushion may be inflated by mouth, the tube then being closed by a captive stopper. During a flight, the cabin of the aircraft is pressurised, typically to 8.5 p. s. i. , and, under normal circumstances, this causes no problem with an inflatable cushion. However, in certain circumstances the air in the aircraft cabin may be subject to decompression. This need not be catastrophic to the extent that it could endanger the safety of the aircraft, but even in less dramatic circumstances, inflatable cushions can be subject to a pressure differential whereby the air therewithin exceeds the then ambient pressure by up to 9 p. s. i. When conventional inflatable cushions are subject to such a differential air pressure, they can expand significantly and then explode. The effects of this can be harmful to passengers, especially where the cushion is of the neck support kind. It will be appreciated that expansion of such a cushion can cause restriction of the neck, and its bursting can generate a peak sound level of up to 145 db. Sudden impulse sounds of this level can result in rupture of the ear drum ; disruption of the ossic1es/cochlea, leading to temporary, persistent, or even permanent hearing loss; disturbance of the vestibular apparatus, leading to dizziness; and non-auditory stress effects, which can include a peripheral vaso-constriction, increased blood pressure, increased respiratory rate, and

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increased heart rate. The sudden and unexpected sound can give rise to acute stress, even if there is no hearing damage, and could be serious (and potentially fatal) for someone with a pre-existing cardiovascular or coronary disease. The dizziness or imbalance, which could be caused at sound levels below that which could cause physical hearing damage, could have serious impairment on the ability of passengers to evacuate the aircraft quickly, should the situation in fact necessitate that. It will be appreciated that these effects would be present, although perhaps to a lesser degree, in cushions that are used other than in close proximity to the passengers'heads.

It is one object of the present invention to provide an inflatable article, for example a cushion, which may be used in pressurised environments, such as those in a cabin of an aircraft, whereby the above-mentioned disadvantages are obviated, or at least reduced.

In accordance with one aspect of the present invention, there is provided an inflatable article having a predetermined region of weakness arranged to allow gradual deflation of the article upon the pressure within the article exceeding the external pressure by a predetermined amount.

Where the article is provided with a seam, then the region of weakness can conveniently be formed as part of that seam. For example, a seam may be made by high frequency welding, and the welding tool, or the electrode, may be provided with a local high spot, so that overwelding, or alternatively underwelding, at that location would lead to the seam failing there preferentially, and gradually. Thus, the air would be allowed to escape gradually from the article, thus avoiding any explosive effect with its attendant disadvantages.

Advantageously, the region of weakness is arranged such that the inflatable article will gradually deflate when the pressure differential reaches around 2 p. s. i.

In a preferred form, the article is provided as a cushion, which may be of substantially U-shape for convenient use as a neck support. In another preferred embodiment, the cushion may comprise two compartments that are interconnected by a restrictive

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passageway, which may contain a two-way valve. In the latter embodiment, the cushion can conveniently be used as an exercising device so that passengers can place their feet on respective ones of the compartments and by"walking"can pump air to and fro between the two compartments, thereby improving blood circulation and possibly obviating potential problems of deep vein thrombosis, which can effect passengers, for

example vulnerable airline passengers, who remain seated for long periods of time.

, The cushion may be made of polymeric or other suitable material. Inflatable articles, in accordance with the present invention, will now be described, by way of example, with reference to the accompanying drawings, in which :Figure 1 is plan view of a first embodiment in the form of an inflatable neck cushion; Figure 2 is a plan view of a second embodiment in the form of an inflatable foot cushion; and Figure 3 is an isometric view of a high frequency welding tool or electrode for use in the production of the inflatable article.

Referring to Figure 1, an inflatable cushion 2 is of generally U-shape so as to fit around a person's neck to provide support for the head. Such a neck cushion is of the sort typically used in aircraft, for example.

The cushion 2 comprises two layers of polymeric material, only the upper layer 6 being shown. The two layers are welded together at high frequency, typically at radio frequency in the range 3 to 30MHz, to form a peripheral seam 8. The welding equipment is ranged so as provide a region of weakness 10 along a portion only of the seam, and this can conveniently be achieved by providing a high point on either the welding tool or on the electrode of the welding apparatus, as will be described, for example, with reference to the embodiment of Figures 2 and 3.

The cushion 2 is also provided with an inflating arrangement 12, which comprises a short length of tubing that can be closed by a captive stopper.

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In operation, the cushion 2 is inflated by mouth through the arrangement 12 to the pressure required by the user and then closed off. Should the differential in pressure between the air inside the cushion 2 and the surrounding environment be such that the strength of the seam 8 at its weak point 10 is exceeded, then the seam 8 will fail gradually in the region 10, thus allowing the cushion 2 to deflate gently. Thus, in an envisaged application of the cushion 2 as a neck support cushion in the cabin of an aircraft, should there be depressurisation of the cabirl such that there is a pressure differential in excess of 2 p. s. i. , the consequent inflation of the cushion 2 will be insignificant before the seam 8 parts at the region 10. Thus, any adverse reaction from the cushion on the neck 4 of the user will be avoided.

Figure 2 shows a particularly advantageous form of inflatable foot cushion 20 which is divided into two compartments 22,24 that are in communication with one another through a passageway 26. The cushion 20 is provided with an inflating arrangement 28, similar to the arrangement 12 described above with respect to Figure 1.

The foot cushion 20 is of generally rectangular configuration, and is formed from two overlying sheets of polymeric material, only the upper 30 of which is shown in the Figure. The two sheets are welded together by means of a high frequency welding tool 32 (Figure 3) which simultaneously forms a substantially rectangular peripheral seam 34 and a pair of inwardly-directed, U-shaped seams 36 which define the passageway 26 between the two compartments 22 and 24.

As can be seen in Figure 3, the metal welding tool 32 is not only shaped to provide the peripheral seam 34 and the inner seams 36, but is also provided with a projection 38 extending down therefrom that acts as a high spot so as to concentrate heating of the peripheral seam 34 in a region 40 to provide a point of weakness.

The foot cushion 20 is provided as an exercise cushion, which may assist in the alleviation of problems arising from deep vein thrombosis in users, for example aircraft passengers, who tend to sit still for long periods of time. In operation, the cushion 20 is put under the passenger's feet so that they rest on respective ones of compartments 21

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and 24. Alternate depression of the compartments by the passenger's legs against the force of the restricting effect of the passageway 26 then transfers air from one compartment to the other.

Should the pressure of the air within the cushion 20 exceed that of the environment by more than an predetermined amount, say by more than about 2 p. s. i, then the provision of the region of weakness 40 allows the seam 34 to part'gradually so as safely to release the air from within the cushion 20 without any explosive effect.

It is envisaged that features of the embodiments disclosed may be combined with each other as appropriate. For example, a generally U-shaped neck cushion, as exemplified in Figure 1, may be divided into two interconnecting compartments, as exemplified in Figure 2, to produce an inflatable article that can not only serve as a neck, or a foot, support, but also as a leg exercising device.

It will be appreciated that an inflatable article in accordance with the invention may be formed in ways other than by high frequency welding so as to have a point of weakness that will allow it to deflate gradually and safely.

It will be appreciated that cushions in accordance with the invention other than in the form of a neck cushion may be used in environments where the ambient pressure can fluctuate, and seat or back cushions and, foot cushions, for example may also be provided.

It is to be understood that the inflatable article will be arranged to withstand any internal excess pressure that would be expected to arise in normal usage. In conditions where an abnormal pressure differential arises, and particularly where explosive bursting of the article could have disadvantageous effects on people or on the surrounding environment, the region of weakness is preferentially arranged to produce a gradual and substantially harmless deflation of the article.

Claims (10)

1. Claims 1. An inflatable article having a predetermined region of weakness arranged to allow gradual deflation of the article upon the pressure within the article exceeding the external pressure by a predetermined amount.
2. 2. An article according to claim 1, wherein the region of weakness is, or forms a part of, a seam of the article.
3. 3. An article according to claim 1 or claim 2, wherein the region of weakness is formed by a welding process, preferably a high frequency welding process.
4. 4. An article according to claim 1, comprising two overlying layers of material that are welded together to form a seam, and wherein the region of weakness is formed in a portion only of the seam.
5. 5. An article according to any one of the preceding claims, wherein the predetermined pressure differential is approximately 2 p. s. i.
6. 6. An article according to any one of the preceding claims, comprising a cushion.
7. 7. An article according to claim 6, when the cushion is arranged to support a person's neck, the cushion preferably being of substantially U-shape.
8. 8. An article according to any one of the preceding claims, comprising an integral inflating tube that is arranged to be closed by a stopper.
9. 9. An article according to any one of the preceding claims, comprising two inflatable compartments with a restrictive passageway therebetween.
10. 10. An inflatable article substantially as hereinbefore described with reference to the accompanying drawings.