Patent Application
20060230512
The present invention relates to covers for areas of exposed liquid surfaces such as, for example, swimming pools, reservoirs, water or oil tanks. More particularly, the present invention relates to a sealing plug for liquid-tight, e.g. watertight, sealing of hollow flotation elements forming strips of which a cover for a liquid surface, e.g. of liquid-filled container, is made.
Swimming pool covers offer numerous benefits for swimming pool owners. The use of a swimming pool cover is important for reducing heat loss from the swimming pool as well as for reducing fouling by blown leaves and other debris. The use of a swimming pool cover prevents the waste of energy gains, such as for example sunlight, by preventing evaporation. The swimming pool cover converts the swimming pool into a highly efficient energy storage system.
Covers for swimming pools have been widely described over the past years. Most of the described swimming pool covers are formed of polyvinyl chloride (PVC) and comprise a plurality of hollow elements which in general have a substantially rectangular or square shape in cross-section. The hollow elements are filled with air and closed with buttons or sealing plugs, and float on the water of the swimming pool. In most cases, the swimming pool covers serve as protection means and as means for isolating the water from the atmosphere. They provide reduction of consumption of energy necessary for warming up the water.
A problem that arises is that swimming pools are not of standard width. This means that the cover must be cut to length. If hollow flotation elements are used, these will need to be sealed. The seals have to be made easily and reliably and preferably at the place where the strips are stored, i.e. not necessarily at the place of manufacture of the strips.
It is known in the prior art to seal plugs into the hollow flotation elements by gluing them with, for example, silicone or any other suitable gluing material. However, a drying period of about 5 days is required and hence, due to the long drying period, a lot of storage place is necessary, which is known to be a problem.
FR-A-2 747 717 describes a sealing plug which can be inserted into a strip comprising a number of hollow flotation elements. The sealing plug comprises an end plate and protrusions extending from the end plate. Each protrusion comprises tongues or spines. It is a disadvantage of the disclosed sealing plug that it does not liquid-tightly seal the hollow flotation elements.
It is an object of the present invention to provide a sealing plug for use with hollow flotation elements which form the strips of a cover for a liquid surface, e.g. a liquid-filled container, such as, for example, a swimming pool, a reservoir or a water or oil tank. The sealing plug is able to close off reliably and in a substantially liquid-tight, e.g. substantially watertight way the hollow flotation elements and it also does not require long storage time once sealed into the hollow flotation elements. If less storage time is needed, less storage space is needed for storing product until it is ready for shipping and/or use.
The above objective is accomplished by a device according to the present invention.
The present invention provides a sealing plug for liquid-tight, e.g. watertight, sealing of a strip, whereby a plurality of interconnected strips form a cover of a liquid-filled container. The interconnections of the strips are preferably such that they allow at least a limited rotation of one strip with respect to another. The interconnections are also preferably such that the cover can be rolled up for shipping or storage purposes. The liquid-filled container may for example be, but is not limited to, a swimming pool, a reservoir or a water or oil tank. Each strip comprises at least one or at least two hollow flotation elements. The sealing plug according to the present invention comprises:
In a preferred embodiment, the liquid surface may be formed on the surface of a liquid-filled container, e.g. a swimming pool.
An advantage of the sealing plug according to the present invention is that, because of the at least two lips completely encircling the protrusion, the sealing plug provides a liquid-tight, e.g. watertight, sealing of the hollow flotation elements.
A further advantage of the sealing plug according to the invention is that, even if it is not, in addition to being introduced into the hollow flotation elements, sealed to the hollow flotation elements, it will not release automatically, without forces being exerted to it. And even with forces being exerted to the sealing plug according to the invention, it will not be easily released from the hollow flotation elements, due to the presence and the orientation of the lips. Furthermore, the orientation of the lips according to the invention prevent the sealing plug from being released from the hollow flotation elements due to e.g. increase of relative pressure inside the hollow flotation elements resulting from e.g. increase of temperature. Thus, according to the invention, the hollow flotation elements are provided with a static lip seal.
In one embodiment according to the invention, the protrusions have a free extremity oriented away from the end plate and may comprise a calibration part at its free extremity. A function of this calibration part, made from hard material, is to remove little parts, burrs for example, inside the hollow flotation elements which have not been completely removed during the production process of these hollow flotation elements. This removal of e.g. burrs while introducing the protrusions of a sealing plug into the corresponding hollow flotation elements of a strip prevents the damage of lips present on the protrusions and which are made of softer material than the protrusions, in particular of softer material than the calibration parts.
The protrusions may, in an embodiment according to the invention, have a circular shape in cross section. In an embodiment according to the invention, the at least two lips present at the protrusions may have a decreasing height with the highest lip being positioned closest to the end plate and the shortest lip being positioned farthest away from the end plate.
The end plate may be L-shaped or inversely L-shaped in cross-section, or at least in a part of its cross-section.
According to an embodiment of the invention, the L-shaped or inversely L-shaped end plate may comprise at least one, preferably a plurality of upstanding legs and a back plate.
The end plate and the at least two protrusions may be formed of a first material and the lips may be formed of a second material. The first and second material may be different from each other and the first material may be harder than the second material. The calibration part of the protrusions may also be made of the first material. According to embodiments of the invention, the first material may be one of polyvinyl chloride (PVC), nylon or polycarbonate. The second material may be a material with a hardness between 40 ShoreA and 90 ShoreA, and may preferably be a material with a hardness between 70 ShoreA and 80 ShoreA. The second material may for example be one of rubber, thermoplastic elastomer (TPE), ethylene propylene diene monomer (EPDM) rubber or silicone rubber. Optionally, the second material may have a compression set, determined according to a standard ASTM D-395 test method at 23° during 72 hours, of less than 50%, preferably less than 30% and more preferably less than 20%.
Preferably, according to the invention, a TPE material may be used as the second material. Examples of TPE materials are Block or Segmented Copolymers such as e.g. Styrene Triblock Copolymers (e.g. Y-SBR, resp. SBS; Y_-IR, resp. SIS), Thermoplastic Polyurethanes (TPE-U, resp. TPU), Thermoplastic Copolyesters (TPE-E), Polyether/Polyamide Block Copolymers (PEBA, resp. TPE-A) or Blends of Elastomers and Thermoplastics such as e.g. EPDM/PP Blends (TPE-O, resp. TPO), NBR/PP Blends (TPE-NR), NBR/PVC Thermoplastics Blends or Thermoplastic Elastomers based on Halogen Containing Polyolefins (e.g. Alcryn®). Other examples of TPE materials can be found in ‘Rubber Technology Handbook’, Werner Hofmann, Hanser Publishers, 1989, reprint 1996.
According to an embodiment of the invention, at least part of the back plate of the L-shaped or inversely L-shaped end plate may be covered with a layer of the second material. This prevents the edges of the liquid-filled container to be damaged when the cover is being rolled up or down, or when an unrolled cover moves up and down on the liquid due to liquid movement.
In an embodiment according to the invention, at least one upstanding leg, e.g. a first upstanding leg of a plurality of upstanding legs, may comprise a first bulge outwardly oriented with respect to the sealing plug in a first direction, and at least one upstanding leg, e.g. a second upstanding leg of a plurality of upstanding legs, may comprise a second bulge outwardly oriented with respect to the sealing plug in a second direction opposite to the first direction. In case the end plate comprises only one upstanding leg, the first and the second upstanding leg may be the same, but in general the first and the second upstanding legs will be different legs. The first bulge and the second bulge may be different from each other. The second bulge of a first strip may fit to the first bulge of a second strip for better closing of the liquid-filled container.
According to an embodiment of the invention, the strip may comprise e.g. four hollow flotation elements.
In a further embodiment of the invention, a protrusion may furthermore comprise a sealing section suitable for being connected onto a hollow flotation element by sealing. Using this sealing section for being sealed to the second softer material rather than gluing plugs into hollow flotation elements leads to reduced storage time of the covers necessary for drying. This reduces the need for storage place.
The above and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. This description is given for the sake of example only, without limiting the scope of the invention. The reference figures quoted below refer to the attached drawings.
In the different figures, the same reference signs refer to the same or analogous elements.
The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes. The dimensions and the relative dimensions may not correspond to actual reductions to practice of the invention.
Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.
It is to be noticed that the term “comprising”, used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression “a device comprising means A and B” should not be limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.
The invention will now be described by a detailed description of several embodiments of the invention. It is clear that other embodiments of the invention can be configured according to the knowledge of persons skilled in the art without departing from the true spirit or technical teaching of the invention, the invention being limited only by the terms of the appended claims.
The present invention provides a sealing plug 22 for liquid-tight, e.g. watertight sealing of hollow flotation elements 21, 21a-d forming a hollow strip profile for a cover of a liquid-filled container 43, as is illustrated in cross-section in
In
The number of strips 20a-d required to form cover 10 depends on the width of the strips 20a-d, i.e. their dimension in a direction substantially perpendicular to the longitudinal length, in the horizontal direction in the drawing of
Each strip 20a-d of the cover 10 is in the form of a continuous membrane, the membrane having a first major surface 40 and a second major surface 41 and a plurality of longitudinal hollow flotation elements 21a-d depending from the second major surface 41. The term “in the form of” does not limit the cover 10 to any method of manufacture but just describes the apparent outer form. The strips 20a-d, when interconnected, are rotatably connected to each other. Between any two neighbouring hollow flotation elements 21a-d of a same strip 20a-d there is a fluid accessible pathway extending away from the second major surface 41 of the membrane to beyond the two neighbouring hollow flotation elements 21a-d.
An example of a strip 20 with a plurality of hollow flotation elements 21a-d is illustrated in
The hollow flotation elements 21a-d in a strip 20 may be connected to each other such that neighbouring hollow flotation elements 21a-d do not directly contact each other. As can be seen from
Because the flotation elements 21a-d are hollow, air is present inside these hollow flotation elements 21a-d. The air inside the hollow flotation elements 21a-d may be heated because of e.g. sunray radiation. The heat inside the hollow flotation elements 21a-d may then be transferred from the air in the hollow flotation elements 21a-d through the wall of the hollow flotation elements 21a-d to the water of the swimming pool or to the liquid of the liquid filled container 43 by conduction.
The hollow flotation elements 21a-d may be formed of a quite flexible material. For example, the hollow flotation elements 21a-d may be formed of polyvinyl chloride (PVC), polyethylene (PE), polycarbonate (PC), a mixture of PVC and poly(methyl methacrylate) (PMMA) or of a mixture of PVC and acrylonitrile butadiene styrene copolymer (ABS).
According to an embodiment of the present invention, the hollow flotation elements 21a-d may be closed at their longitudinal ends, i.e. at the ends at either side in the longitudinal direction of the hollow flotation elements 21a-d, with a sealing plug 22 so that no water can flow into the hollow flotation elements 21a-d. This is important to prevent loss of floating ability of the hollow flotation elements 21a-d.
A sealing plug 22 according to an embodiment of the present invention is illustrated in FIGS. 4 to 6, which show a perspective view of the upper side (
The sealing plug 22 comprises a number of protrusions 24, the number of protrusions 24 being equal to the number of hollow flotation elements 21a-d on a single strip 20. In the example given, the sealing plug 22 comprises four protrusions 24. The protrusions 24 have the same shape in cross-section as the shape in cross-section of the hollow flotation elements 21a-d. Thus, in the example given, for a strip 20 with four hollow flotation elements 21a-d with a circular shape in cross-section, as illustrated in
At their free extremities, the protrusions 24 may comprise a calibration part 25, as illustrated in
According to the invention, each protrusion 24 comprises at least two lips 26, preferably at least three lips 26, which will be described further in the description and which are formed of the second, softer material.
Furthermore, the sealing plug 22 has an end plate onto which the protrusions 24 are attached. In a preferred embodiment, as illustrated in
In case a plurality of upstanding legs are present at the end plate, the two outer upstanding legs 28 of one sealing plug 22, i.e. in the example illustrated in the drawings the first and the fourth upstanding leg 28a respectively 28d, furthermore each comprise an outward-oriented bulge 31a respectively 31b. In case only a single upstanding leg is present at the end plate (not represented in the drawings), the upstanding leg having a width which is substantially equal to the width of a strip, bulges 31a and 31b may be provided at either side in the direction of the width of the upstanding leg. The bulges 31a and 31b are different from each other, i.e. they are from a first type and a second type respectively, so that they are made to make a bulge 31a of the first type co-operate with a bulge 31b of the second type. For example, bulge 31a may positioned so as to be sidewardly and outwardly oriented at the lower side of the first upstanding leg 28a, while bulge 31b may be positioned so as to be sidewardly and outwardly oriented at the upper side of the last, in the example given the fourth, upstanding leg 28d, as can be clearly seen from
An important function of the optional bulges 31a and 31b is to prevent neighbouring strips 20a-d from being shifted towards each other at the position of the region 38 where two neighbouring strips 20a-d are hingedly connected together (
Furthermore, the shape of the bulges 31a and 31b illustrated in the drawings is selected so as to ensure a fluent movement of the strips 20a-d in an up- and downward direction with respect to each other, i.e. so as to ensure blocking of the hinging connection between two neighbouring strips 20a-d as soon as a certain reference angle (in positive or in negative direction) between both neighbouring strips 20a-d is reached. This is illustrated in
Furthermore, a notch 39 is formed in the sealing plug 22, as is schematically illustrated in
Furthermore, the bulges 31a and 31b may be positioned such that the sealing plugs 22 of two neighbouring strips 20a-d fit to each other as illustrated in
In an embodiment of the invention, at least a part of the end plate, and in particular the part intended to be used in a substantially horizontal direction when covering the liquid-filled container, e.g. back 29 of the inversely L-shaped end plate 27, preferably at least its free extremity, indicated in the figures by reference number 29a, is preferably furthermore covered with a layer of the second material, which is softer than the first material. The second, softer material may, according to the present invention, be a material with a hardness of higher than 40 ShoreA and smaller than 90 ShoreA, preferably a material with a hardness of between 70 and 80 ShoreA. Examples of suitable materials may be rubber, thermoplastic elastomer (TPE), Ethylene Propylene Diene Monomer (EPDM) rubber, silicone rubber, or any other material with a suitable hardness. Optionally, the second material may have a compression set, determined according to a standard ASTM D-395 test method at 23° during 72 hours, of less than 50%, preferably less than 30% and more preferably less than 20%.
Preferably, according tot he invention, a TPE material may be used as the second material. Examples of TPE materials are Block or Segmented Copolymers such as e.g. Styrene Triblock Copolymers (e.g. Y-SBR, resp. SBS; Y_-IR, resp. SIS), Thermoplastic Polyurethanes (TPE-U, resp. TPU), Thermoplastic Copolyesters (TPE-E), Polyether/Polyamide Block Copolymers (PEBA, resp. TPE-A) or Blends of Elastomers and Thermoplastics such as e.g. EPDM/PP Blends (TPE-O, resp. TPO), NBR/PP Blends (TPE-NR), NBR/PVC Thermoplastics Blends or Thermoplastic Elastomers based on Halogen Containing Polyolefins (e.g. Alcryn®). Other examples of TPE materials can be found in ‘Rubber Technology Handbook’, by Werner Hofmann, Hanser Publishers, 1989, reprint 1996.
The hardness and compression set properties for Alcryn® TPE materials, obtainable from Distrupol (www.distrupol.com), are summarised in table 1. This is only by means of an example and is not limiting to the invention.
By covering part 29a of the back plate 29 of the inversely L-shaped end plate 27 with the second, softer material, the borders of the swimming pool or liquid-filled container 43 may be prevented from being damaged by the edges of the cover 10, for example, when the cover 10 is being rolled up or down, or when the cover 10 hits the borders due to movement of the liquid, e.g. water. Furthermore, when the edges of the end plate, e.g. part 29a of the back plate 29 of the inversely L-shaped end plate 27, are covered with a layer of the second material, rolling up or down the cover 10 will make less annoying noise.
The end plate, in a particular embodiment back plate 29 of the inversely shaped end plate 27, may, in an embodiment according to the present invention and as illustrated in
The sealing plug 22 according to the invention furthermore comprises, as already stated hereinabove, around the protrusions 24, e.g. in between the end plate and the calibration part 25 of the protrusions 24, at least a first and a second lip 26, positioned adjacent each other in the longitudinal direction of the protrusions 24. However, in other embodiments, the protrusions 24 may be surrounded by more than two lips 26. In the example given and illustrated in the drawings, each protrusion 24 of the sealing plug 22 comprises four lips 26. A cross-section of the sealing plug 22, according to this specific example, at the position of a protrusion 24 is shown in
According to the invention, at least one and preferably each of the at least first and second sealing lip 26 completely encircle the protrusion 24. By completely encircling the protrusion 24 the at least first and second sealing lips 26 allow liquid-tight, e.g. watertight, sealing off the hollow flotation elements 21a-d by means of the sealing plug 22 according to the present invention.
In embodiments according to the invention the at least two lips 26 positioned on each of the protrusions 24 preferably may all have the same height. However, in other embodiments, the first lip 26a which is positioned the closest to the end plate 27 is preferably slightly higher than the second lip 26b, which in turn is higher than the third lip 26c, etc, the shortest lip 26d being positioned the closest to the free extremity of the protrusion 24. The differences in height of subsequent lips 26 on a protrusion 24 may depend on the number of lips 26 present and the manufacturing tolerance in diameter of the hollow flotation elements 21a-d and preferably are smaller than 2 mm. Hence, according to the invention, the lips 26 on the protrusions 24 are built up with decreasing height in a direction from the end plate 27 towards the free extremity of the protrusion 24.
The hollow flotation elements 21a-d are thus provided with a static lip seal. Because of the above-described orientation of the lips 26 on the protrusions 24 of the sealing plug 22 according to the invention, the sealing plug 22 will, once introduced, e.g. pushed, into the hollow flotation elements 21a-d of a strip 20a-d, seal the hollow flotation elements 21a-d in a reliable way. The sealing plug 22 will not release automatically, without forces being exerted to it and even with forces being exerted to the sealing plug 22 it will not be easily released from the hollow flotation elements 21a-d. Furthermore, the orientation of the lips 26 according to the invention prevents the sealing plug 22 from being released from the hollow flotation elements 21a-d due to increase of pressure inside the hollow flotation elements 21a-d, e.g. resulting from increase of temperature inside the closed-off hollow flotation elements 21a-d.
Furthermore, in particular embodiments of the present invention, the sealing plug 22 may be connected to the hollow flotation elements 21a-d of a strip 21a-d by sealing it with a combination of the second, soft material and ultrasonic butt welds. Using only the second, soft material to seal off the longitudinal ends of the hollow elements 21a-d by means of the sealing plugs 22 may not be satisfying for some kinds of second material, in particular when the second, soft material, e.g. rubber, shows ageing. This means that after a certain period of time and in some particular cases, the second, soft material may degenerate such that the sealing plug 22 does not seal the hollow elements 21a-d for 100% any more, through which, in particular cases, liquid may flow into the hollow element 21a-d which may cause e.g. loss of flotation ability and/or formation of algae inside the hollow elements 21a-d. For sealing the sealing plug 22 to the hollow flotation elements 21a-d the sealing plug 22 according to an embodiment of the invention furthermore may comprise a sealing section 34 in between the upstanding leg 28a-d of the inversely L-shaped end plate 27 and the at least first and second lip 26, the sealing section 34 lying in a plane substantially parallel to the plane of the calibration part 25 of the protrusions 24. The sealing section 34 comprises a small upstanding edge 35 which is oriented substantially perpendicular to the plane of the sealing section 34. This upstanding edge 35 may be used for sealing the sealing plug 22 onto a hollow flotation element 21a-d. The sealing section 34 and its edge 35 are made from the first material, which in this case should be a material which can be connected to the material of the flotation elements 21a-d by welding.
Hence, independent from the fact whether the sealing plug 22 is sealed to the hollow flotation elements 21a-d or not, the sealing plug 22 according to embodiments of the present invention provides a reliable sealing of the hollow flotation elements 21a-d and hence leads to liquid-tight, e.g. watertight, sealed hollow flotation elements 21a-d and thus a high quality cover 10 for a liquid-filled container 43.
A further advantage of the present invention is that the time for drying of the cover 10 and thus the storage time can be reduced to 0 days if the sealing plug 22 is not being sealed to the hollow flotation elements 21a-d and to 1 day when the sealing plug 22 is sealed to the hollow flotation elements 21a-d with the method as described above. For prior art sealing plugs, 5 days of drying are required when, for example, silicone is used to seal the sealing plugs 22.
In
According to a preferred embodiment of the invention, the sealing plugs 22 and the hollow flotation elements 21a-d may be manufactured such that they have a constant design. This means that the sealing plugs 22 may be the same for both longitudinal ends, i.e. extremities, of the hollow flotation elements 21a-d.
Depending on the climate, an upper part, e.g. the upper half, of the hollow flotation elements 21a-d may be transparent or translucent or white. In case the upper part is transparent or translucent, sunlight is absorbed in the hollow flotation elements 21a-d where it heats the air present, and the heat of the sunlight is then transferred to the water of the swimming pool or to the liquid in the liquid-filled container 43. This may be applied in countries where no very high outside temperatures are reached, even in summer. In that way, sunlight may be used to warm up, for example, the water of the swimming pool. When, however, the upper part of the hollow flotation elements 21a-d is white, sunlight is reflected by the hollow flotation elements 21a-d and heat will not or not substantially be transferred to, for example, the water of the swimming pool or oil in an oil tank. The latter may, for example, be applied in southern countries having a warm climate, where it is not necessary to additionally warm up the water of a swimming pool, or when it is desired not to heat up liquids such as oil stored in a reservoir.
In embodiments of the invention, a lower part, e.g. the lower half, of the hollow flotation elements 21a-d may be made dark or infra-red radiation absorbing, e.g. it may be painted black, especially matt black, or dark blue. The dark colour may also be obtained during extrusion or co-extrusion. By doing so, the amount of sunlight that is able to reach the water of the swimming pool or the liquid in the liquid-filled container is reduced and therefore the development of algae in the water or liquid may be significantly reduced or may even be prevented because photosynthesis is no longer supported. Furthermore, heat transfer between the air inside the hollow flotation elements 21a-d and the water of the swimming pool or liquid in a liquid-filled container 43 may be enhanced, because the black painted material shows a higher adsorption for sunlight.
A cover 10 according to the invention, as already described above, comprises a plurality of strips 20a-d as described in the embodiments above. The number of strips 20a-d that are to be connected to each other to form the cover 10 depends on the length of the swimming pool or liquid-filling container 43 that has to be covered by the cover 10. The strips 20a-d may be connected to each other by means of a first and second interconnection means, e.g. female/male interconnection means 36 resp. 37 provided at transversal sides of the strips 20a-d. As can be seen from
It is to be understood that although preferred embodiments, specific constructions and configurations, as well as materials, have been discussed herein for devices according to the present invention, various changes or modifications in form and detail may be made without departing from the scope and spirit of this invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 04447230.6 | Oct 2004 | EP | regional |
