IE53045B1 - Energy conversion apparatus - Google Patents

Description

This invention relates to energy conversion apparatus, suitable for conversion of the energy in waves in a body of liquid into a more readily usable form. In particular, the invention concerns the utilisation of a flexible bag device, used in a particular fashion to give good energy conversion characteristics.

The flexible bag essentially is located to one side of a reaction member, herein referred to as a spine, against which wave forces are exerted. The flexible bag is located between the reaction member and the oncoming waves so that it will be cyclically compressed and expanded. Utilisation is made of this cyclical compression and expansion in order to pump fluid, such as air, within the bag in order to drive a.prime mover,, such as a turbine. -- - The present invention is concerned with the mounting and design of the bag in such a system and although specifically single bags are described hereinafter, in a practical arrangement, the spine will carry a plurality of said bags with the bags fluidically interconnected.

The design of bag and its mounting on the reaction member is, as can be appreciated, extremely important and critical. As the bag will be required to flex many times, and in all types of conditions, it is important that the bag design avoids high stress areas, and also that there should be as little as possible abrading contact between the flexibility bag and the spine, as the latter will probably be constructed of concrete.

In accordance with the invention there is provided an energy conversion apparatus for location in a body of water to extract and convert energy of waves in said body of water, said apparatus comprising a reaction spine for location in the body of water in a predetermined in use position, and at least one flexible bag which has passage means for the intake and expulsion of fluid into and out of the bag, and wherein the bag is mounted to a side of the spine so as to 10 collapse and expand under the influence of the waves whereby fluid can be driven from and induced into the bag through said passage means and such fluid movement can be used to drive a suitable prime mover,· and wherein the bag has a front side for facing oncoming waves and a rear side which faces the spine, the rear side being sufficiently free of the spine so that in use water of the body of water can locate behind the rear side and the spine surface keeping the rear side out of contact with the spine, so that by compression of the bag by an oncoming wave meeting the front side, the fluid in the bag is forced out of the bag by virtue of the reaction of the volume of wetter between the rear side and the spine.

Preferably, there is a common passageway from the top end of the flexible bag which serves as an inlet and an outlet ao that the passageway can couple with a conduit containing a uni-directional self-rectifying turbine, such as is disclosed in our co-pendingr^application No. 8216727, for the provision of shaft energy by virtue of the forward and rearward flow of fluid through the conduit by virtue of the compressing and relaxing of the flexible bag due to the wave forces.

Preferably, the single passageway is located at a position such that the bag experiences minimum folding during compression and relaxation, and to this end the passageway is at one of the top corners of the bag with a dummy passageway at the other corner, whereby the need to fabricate the top corners of flexible material is removed. Fabricated top corners are areas of 5 potential failure in use because the material at such corners folds or tends to fold in use.

The inlet and outlet passageways may be defined by a conduit which leads to a module comprising a sleeve containing the uni-directional turbine, the sleeve being coupled to a chamber inside the spine. When there are two of said passageways, the second passageway may be defined by a rigid, but blanked off conduit so that it is a dummy conduit. The bag I5 corners wrap round the conduits, which will be round in section, whereby folding of the bag material in use can be avoided.

The said module and bag may be located outside the spine and may be removable for repair and replacement.

Preferably, there will be a plurality of said bags, each with its own module and each communicating through its module with the said chamber.

Each bag preferably comprises a front panel, a rear panel, the front and rear panels being connected together along the bottom edge of the bag, sides of semi-conical shape and a top of semi-cylindrical shape, 30 the passageways being connected with the bag at the corners and the tops of the sides and the ends of the top being wrapped around the conduits forming the passageway. The said conduits may be rigid or may be of the same flexible material as the bag.

In an alternative arrangement, the flexible bag may be held in suspended position by being mounted on a support arrangement connected to the top corners of the bag and mounted on the spine. The support arrangement may be constructed so as to be adjustable and by suitable adjustment, it may be arranged that the bag rear side is kept out of contact with the spine during operation, for normal wave conditions.

In the alternative arrangement the bag may be generally pillow-shaped, with one of the longer edges forming the said bottom edge and as regards the longer edge forming the upper edge, in the centre of this edge there may be an Integral common inlet and outlet constructed of flexible material of the same material as the front and rear sides of the bag.

Embodiments of the present invention will now be described by way of example and with reference to the accompanying drawings, wherein:Fig. 1 is a side view of a flexible bag and spine section of an energy conversion apparatus; Figs. 2, 3 and 4 are respectively a sectional side elevation taken on the lines A-A of Fig. 1; a plan view of the section of apparatus shown in Fig. 1; and a fragmentary sectional view taken on the line B-B of Fig. 1; Fig. 5 is a diagrammatic perspective elevation of a section of spine showing two flexible bags each according to the invention, and each mounted on a spine according to the invention; and Fig. 6 is a diagrammatic sectional elevation of one of the flexible bags shown in Fig. 5, the section being taken on the line II-II in Fig. 5.

Referring to Figs. 1 to 4 of the drawings, an elongated hollow concrete member 10, hereinafter referred to as a spine forms a support structure for a number of flexible bags 12, of which only one is shown in the drawings, each being filled with air. The bags are generally pillow shaped, with the longer dimension running in the direction of the length of the spine, and the lower edge 14 of each bag is connected to the lower edge 16 of the spine 10 as shown clearly in Fig. 2. Each bag 12 comprises a front panel 18 and a rear panel 20 connected by semi-conical sides 22 and a semicylindrical top 24, thereby to form an enclosure for the pumping fluid, which in this case will be air. The said panels may be sewn or otherwise connected together or alternatively the whole bag may be moulded in one piece.

This embodiment of the invention is advantageous in the design of the corners 26 of the bag 12, and their connections to rigid conduits 28. Conduits 28 are of L-shape in side view as shown in Fig. 1, and have an outlet 30 which is coupled to a turbine generator module 32 containing a uni-directional self-rectifying turbind, for example the type disclosed in our copending British patent application No. 8216727 and from the module 32, an elbow pipe 34 connects to a chamber 36 in the spine 10. The said chamber 36 in fact forms a common manifold aerodynamically coupling the interiors of all of the bags 12, through the associated turbine generator modules 32.

Because in the region 26 of the corners of the bag 12 which are connected to the rigid conduits 28, a semiconical side meets a semi-cylindrical end 24, by appropriate positioning of the conduit and by dimensioning of same, the said side 22 and semicylindrical top 24 can be wrapped round the conduit 28 with minimum stress on the flexible fabric of the bag 12 so that in use, during the flexing of the bag, there will be no creasing or folding of the flexible material in the region 26 of the corners, which is usually a 5 problem with bag design. Suitably, the conduit 28 will meet the bag corner at an angle intersecting the semi-conical and semi-cylindrical side and top 22, 24 in a section which is a semi-circle, or is very near a semi-circle so that the said side and top of the bag 1° will wrap round the conduit 28, which will be a circular section of the same diameter, with minimum or no stress. If there is any tendency of the corner to crease in use of the apparatus, then such tendency can be counteracted by the flexibility of the fabirc by slightly stretching the bag corner around the rigid conduit.

As each bag 12 is to be associated with its own turbine and generator module 32, then one of the outlets at one 20 of the corners will in fact be a dummy and will be blanked off, for example by means of a blanking plate 38.

The said conduits 28 at the corners of the bag 12 serve 25 a number of functions including that they also serve to support the flexible bag 12 outwardly of the spine as shown in Fig. 2, so that there will be no abrading contact between the rear 20 of the bag and the spine surface 40 as the bag compresses and expands in use, 20 and furthermore the utilisation of the rigid support conduits enables the utilisation, of turbine/generator modules 32 which can be located outside the spine 10, (in contradistinction to the embodiment of Figs. 5 and 6) and therefore can be easily removed and replaced, simplifying maintenance of the apparatus considerably. Heretofore, it has always been thought necessary- to embody the prime mover and energy conversion unit such as the generator and turbine inside the spine for protective purposes.

Although it is desirable to use rigid conduits for coupling to the corners of the bag, it is to be stressed that this is not necessary and is possible to use flexible conduits. Similar advantageous results are achieved using flexible conduits in that creasing of the bag is limited or prevented at the corners by providing conduits thereat.

In the use, the apparatus will of course be located in a body of liquid in which there are waves, the apparatus being located so that the waves approach in the direction indicated in Fig. 2 by arrow 41. The bags 12 are filled with air at a predetermined pressure in order that they will take up a particular shape, as shown in Fig. 2. Because the bags are spaced by an interval 42 as shown in Fig. 1, the water of the body of liquid gets behind the bag in the region 44 shown in Fig. 2, and when an oncoming wave meets a bag, it flattens as indicated by dotted lines 43 in Fig. 2, thereby forcing the air out of the bag and out of the outlet 28, through the associated turbine generator module and into the interior of the spine. The movement of the air through the turbine generator module 32 drives the turbine, which in turn drives the generator to produce electrical energy. When the wave recedes, and the bag once more takes up the shape shown in full lines in Fig. 2, air is induced back or forced (by other bags exhausting into the spine), into the bag, and again the turbine is driven, in the same direction as it is uni-directional, continuing the output of electrical energy.

The bags exhaust into and draw from the interior of the spine cyclically in sympathy with the wave forces, and β as the waves will inevitably be out of phase along the length of the spine, at any one time some bags will be charging air into the manifold, whilst others will be drawing air therefrom, but the net result will be aggregated electrical energy from all modules 32.

Figure 4 shows a view in the direction of the arrows BB, to indicate how the bag side and top wrap round the conduit in a minimum stress fashion.

A considerable advantage of this embodiment of the invention is that each bag can be constructed from flat sheets of flexible material and it is not necessary to form any pre-formed curved shapes. Clearly the semicylindrical top and the semi-conical sides can be constructed from flat sheet material in addition to the front and rear of the bag. However, in larger versions of the bag it may be desireable to avoid joins in the material and mould the bags in one piece using fibre reinforced fabric.

The conduits may be of steel and form the sole upper anchor points for the bag, the holding taking place at the points of least stress on the bag during an operational cycle.

Referring now to Figs. 5 and 6 of the drawings, in Fig. 1 there is shown a section of an elongated spine 110 which is for positioning in a body of water such as the sea. The spine, in a practical example, may be of the order of 15 metres deep by 10 metres wide, and may be of a nature to be buoyantly supported by the sea, or it may be mounted in fixed position by a suitable supporting means extending from the sea bed. The spine is shown as being generally rectangular, with the longer sides vertical, and mounted on one of the vertical faces, the face which locks into the oncoming waves whose direction is indicated by arrow 112, are mounted a plurality of independent flexible bags 114, each shaped generally like a pillow and comprising (Fig. 6) a front face 18 and rear face 120. The 5 bottom edge 122 of the bag is firmly connected to the lower portion of the spine as shown, whilst the upper edge has centrally thereof and integral therewith a single outler/inlet pipe 122 which couples to a conduit 124 inside the spine, such conduit 124 containing a 10 self-rectifying uni-directional turbine 126 which may be of a nature as set forth in our co-pendingy®1”^’5^1 application No. 8216727;. Conduit 126 connects with a common manifold 127.

The bag is of a flexible material such as a reinforced rubber, and the pipe 123 is integral therewith and of the same material.

The principle of operation is quite simple and is 20 described with reference to Figs. 1 to 4 in that as the waves meet the flexible bags 114, they deflect same compressing the bag and forcing the fluid contained therein, which will normally be air, from the interior of the bag through pipe 122, conduit 124 and past turbine 126 which is driven to provide shaft energy, and that shaft energy can be converted to electrical energy by suitable electrical conversion means connected to the turbine shaft. As the wave recedes, air is drawn or is forced back (by virtue of the 20 fluidic coupling of all the bags) through the turbine 126, which continues its rotation in the same direction because of its design, from the common manifold 127 inside the spine which links all of the flexible bags.

This embodiment also provides a novel bag design and mounting.

It will be noticed that the bag 114 is connected to the spine only at or along the bottom edge, and the rear side 120 at worst merely rests temporarily against the spine surface, and at best is kept out of contact with the spine surface throughout operation by suitable positioning of the support arrangement 130 for the top edge of the bag, such support arrangement comprising support struts 132 and 134 which are pivotally mounted at points 132A, 134A on the spine and which may be adjustable in length to position the top edge of the bag 114 in the.static position outwardly of the reaction face of the spine, such struts supporting rods 126 attached to the bag top corners. The rods 132 and 134 are connected by a slide block connection 135.

It has been found in testing a model of this embodiment that water locates behind the rear side 120 of the bag and in front of the spine face, and when an -oncoming wave meets the front side 118 of the bag 114, the effect is that the front and rear sides of the bag are pushed together by volumes of water on opposite sides, and the volume of water between the spine and rear face acts essentially as standing water and its level simply increases and fails as the bag expands and contracts.

Fig. 6 shows in dotted lines the position which the bag takes up under maximum compression, whilst the full line position'shows the bag in the most relaxed condition.

In setting up the apparatus for operation, the interior of the common conduit 127 is pressurised as described in relation to the Fig. 2 arrangement, so that the bags are also pressurised to a pre-set level which matches the most: common wave spectrum which will be expected of water in which the apparatus will be located.

Claims (12)

1. An energy conversion apparatus for location in a body of water to extract and convert energy of waves in said body of water, said apparatus comprising a reaction spine for location in the body of water in a 10 predetermined in use position, and at least one flexible bag which has passage means for the intake and expulsion of fluid into and out of the bag, and wherein the bag is mounted to a side of the spine so as to collapse and expand under the influence of the waves 15 whereby fluid can be driven from and induced into the bag through said passage means and such fluid movement can be used to drive a suitable prime mover, and wherein the bag has a front side for facing oncoming waves and a rear side which faces the spine, the rear 20 side being sufficiently free of the spine so that in use the water of the body of water can locate behind the rear side and the spine surface keeping the rear side out of contact with the spine, so that by* compression of the bag by an oncoming wave meeting the 25 front side, the fluid in the bag is forced out of the bag by virtue of the reaction of the volume of water between the rear side and the spine.

2. An apparatus according to Claim 1 wherein in the 30 in use position, the bag is connected to the spine along a lower edge thereof, and the said passage means is located at the top of the bag, so that as the fluid in the bag is forced out of the bag it is forced upwardly in that the volume of water between the rear 35 side of the bag and the spine increases in height rather than being expelled sideways from behind the bag.

3. An apparatus according to Claim 2, wherein the passage means comprises a common passageway from the top end of the flexible bag which serves aa an inlet ' 5 and an outlet and the passageway couples with a conduit containing a uni-directional turbine, for the provision of shaft energy by virtue of the forward and rearward flow of fluid through the conduit by virtue of the collapsing and expanding of the flexible bag.

4. An apparatus according to Claim 3, wherein the bag is included in a replaceable module located to the outside of the spine. 13

5. An apparatus according to Claim 4, wherein the module includes the uni-directional turbine and said conduit, of which the outlet is coupled to a chamber inside the spine. 20

6. An apparatus according to Claims 3, 4 or 5, wherein the bag is rectangular, pillow shaped, and is for use with its longer direction horizontal.

7. An apparatus according to Claim 6, wherein said 25 common passageway is at one of the upper corners of the • bag.

8. An apparatus according to Claim 7, wherein there is a dummy passageway at the other upper corner of the 30 bag.

9. An apparatus according to Claim 8, wherein the bag is made up of front and rear panels joined together at the lower side of the bag and joined at the sides by 35 semi-conical panels having the apices at the lower side of the bag, and by a semi-cylindrical panel at the upper side of the bag, the said common passageway or 530 45 each of the common passageway and dummy passageway being a rigid pipe around which an end of the semicylindrical panel and the adjacent large diameter and of the semi-conical panel are wrapped.

10. An apparatus according to Claim 8 or 9, wherein there are two or more of said modules, and as regards the bags of adjacent modules, the common passageway of one bag defined by a common L-shaped pipe containing a 10 blanking plate to make a section of the pipe the dummy passageway and the other section of the pipe is open to the associated module.

11. An energy conversion apparatus substantially as

12. 15 hereinbefore described with reference to the accompanying drawings.