GB2215057A - Pressure sensor in an inflatable article - Google Patents

Abstract

An inflatable article has a warning device (121) mounted in one wall (10) for indicating when the pressure inside the article is too large for the article to withstand, to prevent the article from being broken at its seals because of over-inflation. The warning device is made of a pressure-sensitive material and when a predetermined pressure is reached, is pushed outwardly. To make it more noticeable it is mounted near the air inlet (11) of the article. The article may be a toy lilo, boat or swimming pool. The device may comprise a spring loaded piston, may be incorporated in the air inlet valve or combined with pressure relief means. <IMAGE>

Description

PRESSURE SENSOR IN AN INFLATABLE ARTICLE The invention relates to an inflatable article, which has a device capable of indicating the pressure inside the article.

A typical inflatable article is made from a number of sheets of plastic sealed at their edges by a high-frequency sealing method. When the article is inflated, it takes on a different shape due to the air inside the article. The air can be released after the article has been used and this allows for easy storage of the article. When such an article is inflated, it can float on water, and this enables such articles to be used as children's toys and swimming aids such as inflatable lilos. However, all inflatable articles have the serious defect that they are easily damaged by over-inflation to a pressure greater than the sealing can withstand. This makes inflatable articles unreliable, so making them unpopular with consumers not only because of their short life but also because it makes them dangerous to use.Damage to an inflatable article which is a childs toy only spoils the enjoyment of the child concerned. A swimmer, however, who uses an inflatable article as a support may find himself in a very dangerous position if the support fails.

In spite of manufacturers warnings in the manuals, which advise the customer not to over-inflate the article, very few people use a pressure gauge, and therefore few customers can be sure whether or not the pressure inside the article exceeds the maximum pressure which the seals can withstand. It is possible to test the pressure of the article by hand, by pressing down on the surface of the article; however this method lacks accuracy. Another problem is that, in use, the weight of the customer on the article increases the pressure inside the article. If this increased pressure is larger than the maximum pressure which the seals can withstand, then the inflated article may be damaged while it is being used. The use of a pressure gauge to measure the pressure inside the article is expensive, and also inconvenient for the customer to use.The present invention seeks to provide a safe inflatable article with an increased life span.

According to the present invention there is an inflatable article having a warning device sensitive to air pressure. If the pressure inside the inflatable article rises above the maximum which the seals of the article can withstand, then the device will undergo a change due to the pressure, and display this condition so that the user can be made aware of the situation and stop inflating the article.

Embodiments of the invention will now be described, by way of example, and with reference to the accompanying drawings, in which: Figs. 1 and la show a first version of a warning device for use in an inflatable article according to the present invention; Figs. 2 and 2a show a second version of a warning device for use in an inflatable article according to the present invention; Fig. 3 shows a third version of a warning device for use in an inflatable article according to the present invention; Fig. 3a shows a fourth version of a warning device for use in an inflatable article according to the present invention; Fig. 4 shows a first version of a combined one-way valve and warning device for use in an inflatable article of the present invention;; Fig. 5 shows a second version of a combined one-way valve and warning device for use in an inflatable article according to the present invention; and Fig. 6 is a detail of the warning device in Figs. 4 and 5.

Referring first to Fig. 1, which shows a first advanced warning device which may be used in the present invention (which is the most simple and effective). The inflatable article 10 has an air inlet 11, and a warning device 12 mounted near the air inlet 11. The warning device 12 has a detecting means 121 which has the form of a dish. When the bottom 122 of the detecting means 121 is in its normal position (having a convex shape), as shown in Fig. la, this indicates that the pressure inside the inflatable article 10 is below the maximum level which the seals of the inflatable article 10 can withstand.When the bottom 122 of the detecting means 121 is forced to project outward from the surface (i.e. adopt a concave shape) by the pressure inside the inflatable article 10, as shown in Fig. ib, this indicates that the pressure inside the inflated article 10 is above the maximum level which the seals of the inflated article 10 can withstand. In this state, if the user continues to inflate the article, it will be damaged (due to the high pressure inside the article). Therefore, when the bottom 122 of the detecting means 121 projects outward from the surface of the article, the user should stop inflating the article 10 at once, and then release some of the air from inside the article until the bottom 122 returns to its original position as shown in Fig. la.

Fig. 2 shows the detecting means 121 connected to a releasing means 14, which is a stick 141 connected to the bottom 122 of the article and a cup 142 mounted on the other end of the stick 141. The surface of the inflated article 10 nearest to the stick 141 and inside the cup 142 has at least one hole 101 which the air can pass through.

When the pressure inside the article 10 is below the critical level, the periphery 143 of the cup 142 will be firmly in contact with the surface of the inflated article 10, and no air can be released through the hole 101, as is shown in Fig. 2a. If, however, the pressure inside the article 10 becomes greater than the maximum pressure which the seals of article can withstand then the bottom 122 of the detecting means 121 projects upwards. This will cause the stick 141 to be raised as well, and as shown in Fig.

2b, the air inside the article 10 may flow out through the hole 101 of the article 10 until the pressure inside the article returns to below the critical level. An air inlet may be mounted on the cup 142 to enable the user to inflate the article 10. With this arrangement, the user can easily see if the pressure rises above the critical level.

The embodiments described above are suitable for an inflatable article of small size. If the inflatable article is large, for example, a boat or a swimming pool, then the embodiments described above may not be suitable.

Fig. 3 shows a warning device in the wall of an inflatable article 10, mounted on a circular base 15 which has a hole 151 in the middle, through which air can flow in and out.

Around the hole 151 a wall 152 extends upwardly. This tubular wall 152 has a screw-thread 153 at its top. An Oring 154 is mounted on the circular base 15 and a pressing plate 155 is mounted upon the O-ring 154. This stops air from flowing out of the article. An indicating tube 156 is mounted upon the pressing plate 155; the indicating tube 156 can be moved by the air when the pressure in the article is too high. Because the height of the tube 156 is the same as the height of the wall 152, movement of the tube 156 due to the air pressure in the article may easily be seen. A spring 157 is sleeved on the indicating tube 156 and abuts a cover 158 which has an opening 159 to allow the tube to project outwards. The diameter of the opening 159 is larger than the diameter of the indicating tube 156, but is smaller than the diameter of the coil spring 157.

In this version of the device, the stiffness rating of the spring 157 may be used to regulate the pressure inside the inflatable article. If the pressure inside the inflatable article 10 is normal, the indicating tube 157 will not move out. When the indicating tube 156 moves, this signifies that the pressure in the article is above the critical level which the seals of the article 10 can withstand. The user should then stop inflating and release some air from the article. A one-way valve 160 may be mounted on the pressing plate 155, to enable this embodiment to be used as an air inlet.

Fig. 3a shows a similar device to that shown in the embodiment of Fig. 3. Inside the circular wall 152 a frame 153' has passages 154' and an O-ring 155' mounted upon the frame 153'. A piston 156' is also mounted on the frame.

The piston 156' has a spring 157' sleeved thereon to bias the piston 156' toward the O-ring 155' to prevent air from flowing out of the hole 151 in the circular base 151. The piston 156' also has a bottom 158'. In this embodiment the rim of the wall 152 has two different heights on different sides A and B. When the user turns the bottom 158' and rotates the piston 156' through 90 degrees, the piston 156' is held in a position in which there is clearance between the piston 156' and the O-ring 155'. The air can then flow out continually from inside the article. As described above, the spring 157' could be used to regulate the pressure inside the article. The tubular wall 152 may also have a cover 158' to protect it. Figs. 4 and 5 show two embodiments which can be used as a warning device, and also as air inlet/outlet devices which enables the air to be released quickly.

In Fig. 4, the warning device is manufactured as an air inlet 20, and a one-way valve 201 is mounted inside the upper portion 200 of the air inlet 20; the air inlet 20 has holes 203 in the wall. A rubber O-ring 204 is mounted outside the holes 203 to stop the air from being released from inside the article. The rubber O-ring 204 performs the same function as the springs, that is to say its stiffness can be used to define the critical level of the air pressure inside the article 10 above which air should be released. While inflating the article 10, the excess air can be released through holes 203, as the rubber 204 expands due to air pressure inside the article 10 above the critical level. This air inlet 20 also has a cup 205, the cup 205 can be screwed onto the air inlet 20 to protect the air inlet 20. Between the air inelt 20 and the cup 205, an O-ring 206 is mounted as a seal.In this embodiment, the air inlet 20 cannot move relative to the article 10, and it takes time to release the air. But this problem can be easily resolved by the following device.

In the device shown in Fig. 5, the warning device is an air inlet 20' as in Fig. 4. However, the air inlet 20' is screwed onto the circular base 15 so that, if the user wants to release air from inside the article, he must unscrew the air inlet 20' from the circular base 15. The air inside the article 10 can then be easily released. It takes only a short time to release the air.

In both the above embodiments, the O-ring 204 has a natural position which represents a pressure below the critical threshold. This can be seen by looking at Fig. 6 which shows a section through an O-ring 204, adjacent a hole 203; the natural position is defined by the solid lines. When the O-ring 204 adopts the position shown by the dotted line, air is being released due to pressure inside the article above the critical level. By observing the O-ring during inflation the user has an indication of whether or not the pressure is above the critical level.

Claims (17)

1. An inflatable article having an over-pressure warning device mounted in a wall thereof, the device having a movable part activatable when the pressure within the article exceeds a predetermined amount, to move from a first position to a second position, the second position corresponding to over-pressure of the article.

2. An article according to claim 1, wherein the device comprises a flexible part sealed to the wall.

3. An article according to claim 2, wherein the flexible part of the device is a curved film movable between a concave position and a convex position.

4. An article according to any one of the preceding claims, wherein the device includes means for releasing air from the article when the pressure exceeds the predetermined amount.

5. An article according to claim 4, wherein the air release means is activatable by the movement of the movable part.

6. An article according to claim 5, wherein the air release means comprises a hole in the surface of the article and a releasable seal for that hole, the seal being connected to the flexible part.

7. An article according to claim 6, wherein the seal is connected to the flexible part through a further hole in the surface of the article, the flexible part sealing the further hole.

8. An article according to claim 1, having a housing projecting from a wall thereof, the interior of the housing being in communication with the interior of the rest of the article, and the device comprising a piston at least partially within the sleeve.

9. An article according to claim 8, wherein the piston is resiliently biased towards the base of the housing adjacent the said wall.

10. An article according to claim 8 or claim 9, wherein the piston has an end surface adjacent the base of the housing, that end surface containing a one-way valve to permit air to enter the article.

11. An article according to claim 10, wherein the end surface of the piston, when in its first position, is sealed to the said wall of the article, within the housing by an O-ring.

12. An article according to claim 8 or claim 9, wherein the piston has an end surface which, in the first position of the indicator, seals an opening in the housing remote from the said wall.

13. An article according to claim 12, wherein the end of the housing remote from the said wall has a projecting rim extending around part of its circumference, the rim engaging the end surface of the piston, whereby a gap is formed between the end of the housing and the end surface of the piston, other than at the engagement of the end surface and the rim, when the piston is in the second position.

14. An inflatable article according to claim 1, wherein the device has a one-way valve mounted on the inflatable particle, the one-way valve having holes in a wall thereof the holes being covered by an O-ring, forming the movable part.

15. An inflatable article according to claim 1, wherein the device comprises: a base having a hole therein which is sealed to the surface of the inflatable article, the base having a tubular wall mounted thereon, the tubular wall having a one way valve therein, wherein the movable part is an O-ring mounted over the one-way valve.

16. A device according to claim 15, where said one-way valve has holes in the wall thereof and said holes are covered by the O-ring.

17. A device according to any one of claims 14 to 16 further comprising a cover to protect the one-way valve.

17. A device according to any one of claims 14 to 16, further comprising a cover to protect the one-way valve.

18. An inflatable article having an over-pressure warning device substantially as herein described with reference to and as illustrated in Figs. 1 and la or Figs. 2 and 2a, or Fig. 3, or Fig. 3a, or Fig. 4, or Fig. 4a of the accompanying drawings.

Amendments to the claims have been filed as follows 1. An inflatable article having an over-pressure warning device mounted in a wall thereof, the device having a flexible part adapted to deform, only where the pressure difference across the two sides of the wall exceeds a predetermined amount, from a first shape to a second shape, the second shape corresponding to over-pressure of the article, to remain in that second shape whenever the pressure difference is greater than the predetermined amount and to return to its first shape when the pressure difference becomes less than the predetermined amount.

2. An article according to claim 1, wherein the flexible part of the device is a curved film deformable between a first concave shape and a second convex shape.

3. An article according to any one of the preceding claims, wherein the device includes means for releasing air from the article when the pressure difference exceeds the pre-determined amount.

4. An article according to claim 3, wherein the air release means is activatable by the movement of the flexible part.

5. An article according to claim 4, wherein the air release means comprises a hole in the surface of the article and a releasable seal for that hole, the seal being connected to the flexible part.

6. An article according to claim 5, wherein the seal is connected to the flexible part through a further hole in the surface of the article, the flexible part sealing the further hole.

7. An inflatable article having an over-pressure warning device mounted in a wall thereof, the device having a housing projecting from the wall with the interior of the housing being in communication with the interior of the article, a piston within the housing biased by a resilient means towards the base of the housing adjacent the wall, so that the piston is moved in the housing to indicate the pressure difference on the two sides of the wall, and an 0ring is adapted in the housing for the sealing between the piston and the housing.

8. An article according to claim 7 wherein the end surface of the piston has a one-way valve adapted as an air inlet.

9. An article according to claim 7 or claim 8 wherein the end surface of the piston seals an opening in the housing when the piston is biased to its end position toward the wall.

10. An article according to claim 9, wherein the end of the housing remote from the said wall has a projecting rim extending around part of its circumference, the rim engaging the end surface of the piston, whereby a gap is formed between the end of the housing and the end surface of the piston, when the piston is moved outwardly from the housing by the pressure within the article when that pressure exceeds a predetermined amount.

11. A pressure indicating and auto-releasing device for an inflatable article including: a one-way valve mounted in a wall of the article, the valve having at least one hole on its wall; and an O-ring is adapted to cover the hole on the one-way valve; the O-ring being arranged so that the part of the 0ring covering the hole is deformed when the pressure difference on two sides of the wall of the article exceeds a predetermined amount thereby to release the article.

12. A device according to claim 11, further comprising a cover for protecting the one-way valve.

13. An inflatable article having an over-pressure warning device substantially as herein described with reference to and as illustrated in Figs. 1 and la or Figs. 2 and 2a, or Fig. 3, or Fig. 3a, or Fig. 4 or Fig. 4a of the accompanying drawings.

14. An inflatable article according to claim 1, wherein the device has a one-way valve mounted on the inflatable article, the one-way valve having holes in a wall thereof the holes being covered by an O-ring, forming the movable part.

15. An inflatable article according to claim 1 wherein the device comprises a base having a hole therein which is sealed to the surface of the inflatable article, the base having a tubular wall mounted thereon, the tubular wall having a one way valve therein, wherein the moveable part is an O-ring mounted over the one way valve.

16. A device according to claim 15, where said one-way valve has holes in the wall thereof and said holes are covered'by the O-ring.