CLAIMS
1. An oil boom (1, 12) comprising elongated float portion (2, 14) and skirt portion (3, 16) connected thereto and hanging from the float portion in the water when the oil boom is in use, thereby supporting the oil boom in the upright position, the float portion comprising a jacket (5, 13) made from a flexible material impermeable to air, and expanding means for expanding the jacket and at the same time filling it with air which flows into the jacket via an air link arranged in the jacket, characteri zed in that the expanding means comprises
- two substantially straight and rigid support structures (6, 8, 17) provided in the jacket (5, 13) and extending longitudinally in the cross-sectional plane of the float portion (2, 14), and
- a spring member (7, 18) connecting one heads of the support structures, allowing the support structures to be pressed towards each other and, when free from pressure, being adjusted to bend the support structures away from each other up to the angle defined by the circumference of the jacket (5, 13) and the lengths of the support structures, in order to form a float portion which has substantially a triangular profile.
2. The oil boom (1, 12) in accordance with claim 1, characterized in that the support structure comprises an arm portion (6, 17) .
3. The oil boom (1, 12) in accordance with claim 1 or 2, characterized in that the support structure comprises a flat sheet (8) which ex- tends in the longitudinal direction of the float portion.
4. The oil boom (1, 12) in accordance with claim 3, characterized in that the sheet (8) is made from foamed plastic or other similar material which is lighter than water in order to promote buoy- ancy of the float portion (2, 14).
5. The oil boom (1, 12) in accordance with any one of claims 1 - 4, characterized in that the spring member is a bending stress spring type coil spring (7) . 6. The oil boom (1, 12) in accordance with any one of claims 1 - 5, characterized in that the spring member (7, 18) is coupled to the jacket (5, 13) on the side opposing the skirt portion (3, 16) of the oil boom, such that when the oil boom is in use, the float portion (2, 14) has a profile substantially shaped as an upward-pointing triangle.
7. The oil boom (1, 12) in accordance with any one of claims 1 - 5, characterized in that the spring member (7, 18) is coupled to the jacket (5, 13) on the side of the skirt portion (3, 16) of the oil boom, such that when the oil boom is in use, the float portion (2, 14) has a profile substantially shaped as a downward-pointing triangle. |
OIL BOOM TECHNICAL FIELD
The invention relates to an oil boom for preventing oil or other impurity, which floats on the surface of the water, from spreading. Specifically, the invention relates to an air-filled float portion which is part of the oil boom construction and opens by itself when the oil boom is taken to use.
BACKGROUND OF THE INVENTION
A wide variety of oil boom constructions provided with a self-inflating float portion are known in prior art. One thing they have in common is that they comprise opening means arranged in the float portion which is designed to float on the surface of the water, in order to open a jacket which forms the float portion and thereby to force air to flow into the float portion. The float portion is typically divided into separate partitions in the longitudinal direction of the boom, the partitions possibly being linked together by means of air passages.
Variations of the most typical self-inflating oil boom construction have been disclosed for example in patent specifications WO 9627711 Al, WO 9518267 Al, US 3901753 A, and SE 340594 B. The disclosed constructions share the characteristic of the opening means comprising a framework which covers the entire profile of the float portion and consists of at least two, as in the solution described in specification SE 340594 B, but most often of four parts pivotally connected to each other. When the oil boom is stowed away, the framework can be compressed such that its sides are pressed towards each other. In order to open the framework, there are one or more vertical springs ar- ranged in the construction, which springs tend to draw the upper and lower parts of the sides of the frame-
work towards each other, such that the framework which consists of articulated parts expands laterally, thereby opening the jacket and forming an inflated float portion. Due to the prior art described above, the known oil boom constructions are complex. In particular the joints of the framework are prone to malfunction, especially during long-term storage. Also the coil spring, which is kept in the stretched position during storage of the oil boom, gradually loses its flexibility, causing the construction to not necessarily open properly when put into use. The spring which is positioned inside the compressed frame also requires space during storage of the oil boom, thereby constraining the compression of the frame. The rigid frames with their relatively large springs and joints also inevitably make the apparatus rather large and heavy. In order to hold the oil booms in the right position in the water, a weight must often be coupled to the float portion, which weight tends to drag the boom partly under the water. Depending on the geometry of the profile of the float portion, the oil boom solutions of the prior art may require the use of rather large weights, with the result that the floating depth of the float portion and fluctuations thereof, for example in the case of surging of the waves, are great. When the floating depth fluctuates in the longitudinal direction of the boom, air flows through the air passages from the partitions of the boom which are deeper in the water into the partitions which are nearer to the surface, which intensifies the fluctuations in the floating depth even more. In this case, some partitions may fall entirely under the water, thereby weakening the reliability of the oil boom functioning. Furthermore, if the air passages between the partitions operate in such a way that the air inside is only able to flow in one direction, then an overpres-
sure of such degree may form in some partitions that they might explode .
OBJECTIVE OF THE INVENTION The objective of the invention is to alleviate the problems of the prior art- referred to above and to disclose a novel oil boom which is light, simple, reliable, and inexpensive.
SUMMARY OF THE INVENTION
The oil boom in accordance with the invention is characterized by what has been presented in claim 1.
The oil boom of the invention comprises an elongated float portion and a skirt portion attached thereto, which skirt portion is also elongated and hangs in the water from the float portion when the oil boom is in use, supporting the oil boom in the upright position. The float portion comprises a jacket made from a flexible material which is impermeable to air, for example rubber or PVC, and expanding means for expanding the jacket and at the same time filling it with air which flows into the jacket via an air link arranged therein. In other words, filling the float does not necessitate blowing air into the float; instead when the float is opened with the expanding means, air is forced to flow into the float due to low pressure.
In accordance with the invention, the expand- ing means comprises two substantially straight and rigid support structures, provided in said jacket and extending longitudinally in the cross-sectional plane of the float portion, and a spring member which connects one heads of the support structures, allowing the support structures to be pressed towards each other, and, when freed from pressure, being adjusted to bend the support structures away from each other up
to the angle defined by the circumference of the jacket and the lengths of the support structures. In accordance with the invention, the float portion has, when free from the pressure of the spring member, a profile of substantially a triangular shape, such that the exact shape of the side of the jacket which is free from the support structures depends on the position of the float, on the mass of the skirt and of the weight which is possibly coupled thereto, and on the coupling point.
Unlike the solutions in accordance with the prior art, wherein the opening means comprises a circular construction which extends around the entire jacket or over the inner surface thereof, the support structures in the expanding means in accordance with the invention cover only part of the circumference of the opened float. In this way, the number of both the support structures of the opening means, and in particular of the joints which connect the support struc- tures and constitute potential points of malfunction, is reduced as compared to the solutions of the prior art. Furthermore, as the only joint which pivotally connects the support structures together at the one heads is realized by means of a spring member that can be realized as a very reliable construction, the possibilities of malfunction are significantly reduced with respect to the known solutions . As the spring member is attached to the one heads of the support structures, the area between the support structures remains free, so that the oil boom can be packed to form a very thin construction for storage. The exact shape of the triangular profile of the float portion can be selected as desired by choosing suitable lengths for the support structures, circumference for the jacket and mass for the skirt and for the weight which is possibly attached thereto.
In one preferred embodiment of the invention, the support structure comprises an arm portion, which may be a simple elongated object made from any sufficiently rigid material. The arm portion may be, for example, a bar which has a circular or rectangular profile, or even a substantially flat strip of material .
In order to provide an oil boom construction which is as light and as affordable as possible, the jacket of the float portion may be made for example from PVC fabric or other such thin and flexible material. In this case, for stiffening the float portion in its longitudinal direction, the support structure shall preferably comprise a flat sheet which extends in the longitudinal direction of the float portion. Preferably, the sheet is made from foamed plastic or other such material which is lighter than water, to promote buoyancy of the float portion.
In one preferred embodiment of the invention, the spring member is a bending stress spring type coil spring. This means herein a coil spring wherein the functional movement is realized substantially at the level of the coil by flexion of the one heads of the wire or the bar which forms the coil, as distinct from compression or extension springs wherein the functional movement of the spring is based on adjusting the length of the spring substantially in a perpendicular direction with respect to the coil level.
The opening means provided in the jacket may be positioned inside or outside the jacket which forms the float portion, or they may constitute part of the jacket itself. They may be, for example, loose inside the float portion or inserted into pockets designed for the opening means. However, in particular in oil boom constructions wherein the float portion comprises a plurality of successively positioned separate partitions, it is advantageous, especially when it comes to
packing of the oil boom, that all opening means of the oil boom is positioned in the same direction.
There are certain preferred options for the position of the float portion with regard to the water surface. Hence in one preferred embodiment of the invention the spring member is positioned on the side opposing the skirt portion of the oil boom so that, when the oil boom is in use, the profile of the float portion substantially forms an upward-pointing trian- gle and the support surface of the float portion is wide. This reduces the floating depth of the oil boom and fluctuations thereof, which in turn reduces air flow between the partitions, thereby increasing reliability of the functioning of the boom. Furthermore, the wide support surface keeps the float portion very firmly in the upright position. The attachment of the support structures, such as foamed plastic sheets, to the jacket may be realized for example by gluing. It is also possible to arrange pockets outside or inside the jacket for inserting the support structures therein. On the other hand, the support members per se do not necessarily need to be coupled to the jacket; instead it may be sufficient to only couple the spring member to the jacket, and then couple the support structures to the spring member.
In a second preferred embodiment of the invention, the spring member is positioned on the side of the skirt portion of the oil boom so that, when the oil boom is in use, the profile of the float portion substantially forms a downward-pointing triangle. In a construction such as this, the mass of the skirt portion and of the weight which is possibly attached thereto, as well as the buoyant force in the water produced by the float portion, can be adjusted such that the apex of the triangle settles at the desired depth in the water. This provides a float portion which is well able to hold its upright position and at
the same time has a tapered lower part, which may be advantageous in certain applications.
The lengths of the support structures and the circumference of the jacket can be dimensioned for the different optional use positions of the float portion, for example such that when the spring member is positioned on the side opposing the skirt, the support surface of the float portion against water becomes wide, and when the spring member is on the side of the skirt, the downward-pointing triangle in the water becomes, in turn, tapered.
Thanks to the characteristics described above, the oil boom in accordance with the invention, as compared to the solutions of the prior art, is very simple, light, inexpensive to produce, and reliable. Furthermore, the oil boom in accordance with the invention, as compared to the prior art, does not require much space when stowed away, so it suits well for use for example in ships, as easily moveable res- cue station equipment, and even in the protection of private coastlines.
DETAILED DESCRIPTION OF THE INVENTION
In the following section, the invention will be described with reference to the accompanying drawings, in which
Figs. Ia and Ib represent cross-sectional views of one oil boom in accordance with the invention in stowed away and use positions, Figs. 2a and 2b represent the oil boom shown in Figs. Ia and Ib as seen from the side and the top, and
Fig. 3 represents a cross-sectional view of one oil boom in accordance with the invention. The oil boom 1 of Figs. Ia and Ib comprises an inflatable float portion 2 and a curtain-like skirt
portion 3 attached to the lower edge of the float portion, with a weight 4 attached to the lower end of the skirt portion. The float portion is formed of a jacket 5, made from flexible plastic or plastic fabric, which is impermeable to air. Two rigid metal bars 6 are arranged inside the jacket in the direction of the cross-sectional plane of the float portion, with their one heads connected to the heads of a coil spring 7 which is coupled to the upper edge of the jacket, such that the spring tends to bend the bars away from each other in the cross-sectional plane of the oil boom. The bars are placed inside flat sheets 8 which are made from foamed plastic or other material which is lighter than water and extend in the longitudinal di- rection of the oil boom.
The following section focuses on the operation of the oil boom in accordance with Figs. Ia and Ib. The coil spring 7 allows the bars 6 and, at the same time, the sheets 8 to be pressed against each other in accordance with Fig. Ia. As compressed into such flat position, the oil boom may be stowed away, for example folded or rolled up. When the oil boom is taken into use and released from external pressure, the coil spring 7 expands the bars 6 and the sheets 8 away from each other, thereby opening the jacket. The opening forces air to flow into the thus formed volume via an air link (not shown in the figures) arranged in the jacket, such that an inflated float with substantially a triangular profile is formed, the float hold- ing the oil boom on the water surface in accordance with Fig. Ib. The exact shape of said substantially triangular profile of the float portion 2 is defined by the lengths of the bars 6 and the sheets 8 in the cross-sectional plane of the oil boom, by the circum- ference of the jacket 5, and by the mass of the skirt 3 and of the weight 4 which is possibly attached thereto. The mass of the skirt 3 and of the weight 4
determine the extent to which the profile of the float portion differs from a triangular shape, and the degree of the fourth angle, possibly formed on the coupling point of the skirt. When the oil boom is in the water, the skirt portion 3, which is coupled to the lower edge of the jacket, and the weight 4 drag the float portion 2 down, thereby keeping the oil boom in the upright position.
As shown in Figs. 2a and 2b, the float por- tion 2 of the oil boom is divided into partitions 9 in the longitudinal direction, the partitions being separated from each other by seams 10, formed by fusing or joining in some other way together the sides of the jacket. Each partition 9 has separate opening means attached to the upper edge of the jacket, the opening means comprising two flat sheets 8 and two pairs of bars 6 which are connected to the sheets, and springs 7 between the bars, for opening the partition to form an inflated float. The sheets 8 and the bars 6 can be placed in- or outside the jacket, into pockets 20 designed for them. Adjacent partitions are connected to each other by means of the air link 11 which passes through the seam between them. In this way, air can flow freely between the partitions, so that each par- tition does not need to be provided with a separate inflation link with a direct connection to the outside air. When the oil boom is taken to use, the jacket opens at each partition for the length defined by the sheets, to form a float. At the ends of the partition, the profile of the inflated float tapers towards the seam between the partitions, as shown in Fig. 2b.
The oil boom 12 of Fig. 3 is formed of an elongated, relatively thick and rigid strip 13 made from rubber. The upper edge of the strip is wrapped around the length 12 of the constructed oil boom, and the sides of the strip brought in this way against each other are connected together for a short section,
such that the wrapped portion of the strip forms the jacket which functions as the float 14 and encloses the air volume . The lower edge of the strip also comprises a volume formed in the corresponding manner, i.e. by wrapping the strip, but in a smaller scale. A metal chain 15 is placed into this volume to function as the weight for the skirt portion 16 of the oil boom, formed by the lower part of the strip. Inside the rubber strip 13 which forms the jacket are ar- ranged metal arms 17, one heads 18 of which are bent in a different direction from the rest of the arm and connected to each other for the bent section. The connection of the arms is positioned in the area of the joint 19 between the sides of said rubber strip. The bent heads 18 of the arms 17 as joined together form a spring-like member which tends to keep the arms at an angle to each other and therefore the jacket open in accordance with Fig. 3. The thick rubber strip in itself and the joint area 19 of the opposite sides of the wrapped strip function as a construction which stiffens the jacket in the longitudinal direction of the oil boom, so that any separate stiffening sheets are not required therein.
The invention is not limited to the examples referred to above; instead its embodiment may λra.xγ freely within the scope of the claims .
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