NL2037122B1 - Anchor line guiding means - Google Patents

Abstract

Apparatus for converting energy from waves in a body of water, the apparatus comprising a main structure having a water resistance surface with a height and a width, said width substantially defining the length of the main structure, the main structure further comprising floating means arranged at both sides of the water resistance surface enabling the main structure to float onto the water with the water resistance surface in a substantially upright position, the apparatus further comprising an anchor line extending at both sides of the water resistance surface, the anchor line being adapted, at both sides of the water resistance surface, to be anchored to a bottom of the body of water and the anchor line being connected to anchor line holding means provided at the main structure, the main structure further comprising conversion means connected to the anchor line holding means and adapted to convert a movement of the anchor line holding means into another form of energy, wherein the main structure further comprises anchor line guiding means provided at both sides of the water resistance surface, each anchor line guiding means being located, when in use, such that a perpendicular projection of each anchor line guiding means onto a plane wherein the water resistance surface extends lays in a central upright area of said plane and wherein each anchor line guiding means is located at a distance from the water resistance surface. Figure 1

Description

Anchor line guiding means

The present invention relates to an apparatus for converting energy from waves in a body of water, the apparatus comprising a main body adapted to float onto the water; anchor lines adapted to be anchored to the bottom of the body of water; and conversion means to convert movement energy into another form of energy. Such an apparatus is also called an anchorable wave energy convertor.

An anchorable wave energy convertor of this kind is known from EP3019738. This wave energy convertor has the drawback that the apparatus has a complex build and is therefore expensive and hard to control during operation.

It is an object of the invention to provide an anchorable wave energy convertor that is cheaper, less complex and easier to use.

To this end, the invention relates to an apparatus for converting energy from waves in a body of water, the apparatus comprising a main structure having a water resistance surface with a height and a width, said width substantially defining the length of the main structure, the main structure further comprising floating means arranged at both sides of the water resistance surface enabling the main structure to float onto the water with the water resistance surface in a substantially upright position, the apparatus further comprising an anchor line extending at both sides of the water resistance surface, the anchor line being adapted, at both sides of the water resistance surface, to be anchored to a bottom of the body of water and the anchor line being connected to anchor line holding means provided at the main structure, the main structure further comprising conversion means connected to the anchor line holding means and adapted to convert a movement of the anchor line holding means into another form of energy, wherein the main structure further comprises anchor line guiding means provided at both sides of the water resistance surface, each anchor line guiding means being located. when in use, such that a perpendicular projection of each anchor line guiding means onto a plane wherein the water resistance surface extends lays in a central upright area of said plane and wherein each anchor line guiding means is located at a distance from the water resistance surface.

The apparatus of the invention has a simple and straightforward build with a water resistance surface and, at both sides, floating means. Basic operation of the apparatus can be explained as follows. Waves in a body of water induce a forward and backward movement of the water. The apparatus of the invention comprises a water resistance surface extending in an upright position. The forward and backward movement of the water will act upon the water resistance surface to force the apparatus in a related backward and forward movement. The apparatus is anchored, via anchor lings, to the bottom of the body of water. Obviously, the bottom of the body of water stands still and does not make a backward and forward movement along with the water. In this context, it is noted that any rigid structure having a significantly larger mass than the apparatus of the invention may function and therefore be considered as bottom of the body of water, even if this large mass technically floats in the water. This results in a movement of the apparatus with respect to the anchor lines, which movement can be converted into another form of energy, for example electric energy. Theoretically, the optimal angular position of the apparatus with respect to the backward and forward movement of the water is the position wherein the water moves perpendicular to the water resistance surface. When the backward and forward movement of the water would be parallel to the water resistance surface, the water will not act onto the water resistance surface and the apparatus would make no significant movement with respect to the bottom of the body of water and consequently no significant energy is converted. Therefore, since the apparatus optimally operates in a single wave-direction, it is called a unidirectional wave energy convertor. In this context, it is noted that in many places around the world, there is one main direction where waves are coming from.

The invention is based on the insight that the simplicity of a unidirectional wave energy convertor is highly beneficial since it makes building and operating the apparatus cheap and simple. However the apparatus will have a tendency to rotate into an angular position further away from the optimal angular position. The invention is further based on the insight that such undesired rotation of the apparatus in the water can be counteracted by connecting the anchor lines in a predetermined manner. This counteraction occurs without active control. In particular, by providing anchor line guiding means at a distance form the water resistance surface, at both sides thereof, a rotational force will be induced by the anchor lines onto the apparatus counteracting the rotation of the apparatus. In this manner, the apparatus will be held in or at least close to its optimal angular position.

Preferably, each anchor line guiding means comprises a roller for guiding the corresponding anchor line. A roller minimizes friction between the anchor line guiding means and the anchor line when the anchor line moves relative to the anchor line guiding means. In this context, it will be clear that the forward and backward movement of the water induces a forward and backward movement of the apparatus with respect to the anchor lines. Thus the anchor lines will move relative to the apparatus which comprises the anchor line guiding means, such that the anchor lines also move relative to the anchor line guiding means. To minimize friction, rollers are provided.

Preferably, each anchor line guiding means is hingeably mounted to the main structure enabling a rotation of the anchor line guiding means with respect to the main structure.

As described above, the apparatus has a tendency to rotate into an angular position further away from the optimal angular position, which tendency is counteracted by the anchor line guiding means. To ensure optimal guiding of the anchor line when the apparatus is rotated out of its optimal angular position, the anchor line guiding means are hingeably mounted. In this manner, the anchor line guiding means can hinge depending on the angular position of the apparatus.

Preferably, each roller is mounted to the main structure via a flexible interconnection element. The flexible interconnection element such as a rope, a line or a chain, which are non-limiting examples, is easy to connect to the apparatus, is reliable and allows for a complex rotation of the roller relative to the apparatus thereby automatically also incorporating the above described hinging functionality.

In an alternative preferred embodiment, each roller comprises a pair of rollers. The pair of rollers are preferably shaped complementary, more preferably as a combination of a convex and a concave roller. The pair of rollers is preferably mounted to the main structure via an upright rotational shaft such that the pair of rollers can rotate relative to the main structure.

Preferably, each roller of the anchor line guiding means is located at a height below the rotation means and preferably at a height below the floating means. Tests and simulations have shown that this is an optimal height for the anchor line guiding means.

Preferably, the anchor line comprises a first set of anchor lines extending to one of the sides of the water resistance surface and comprises a second set of anchor lines extending to another of the sides of the water resistance surface. Each set may comprise one or more anchor lines. By providing different sets of anchor lines extending to the two different sides of the water resistance surface, the connecting of the anchor lines to the apparatus in order to convert energy becomes more simple.

Preferably, the anchor line holding means comprise rotation means. Rotation means provide a simple mechanism to hold an anchor line and to capture a movement of such anchor line. Furthermore, a rotation means can be easily connected to an energy convertor.

Preferably, each of the anchor lines of the first set and the second set is adapted to be rolled up and unrolled from the rotation means. In operation, the first set of lines is rolled onto the rotation means while the second set of lines is unrolled from the rotation means and vise versa.

The back and forth movement of the apparatus in the water induces an alternating clockwise and counterclockwise rotation of the rotation means which may be converted into another form of energy by the conversion means.

Preferably, the rotation means comprises rotation segments for each anchor line.

By providing a rotation segment for each anchor line, each anchor line can be separately rolled onto and unrolled from the rotation means. Further preferably, the rotation segments are connected to a single rotation shaft. This simplifies the construction.

Preferably, the first set of anchor lines comprises at least two anchor lines and wherein the second set of anchor lines comprises at least two anchor lines. Using two anchor lines at each side further improves the stability of operation of the apparatus. These two anchor lines induce a rotation counteracting the tendency of the apparatus to rotate into an angular position further away from the optimal angular position. Furthermore, the two anchor lines allow a symmetrical connection to the apparatus, which is better to avoid unwanted rotation of the apparatus.

Preferably. the anchor line holding means and conversion means are located above the water resistance surface. Preferably, the combination of the water resistance surface and the anchor line holding means are symmetrical about an upright plane transverse to the water resistance surface. A symmetrical structure simplifies the construction and optimizes the operation of the apparatus. In this context it is noted that preferably only one of the first set of anchor lines and second set of anchor lines comprises an uneven number of anchor lines. The one set of anchor lines comprising the uneven number may be connected centrally to the apparatus. The skilled person understands that only one anchor line can be connected centrally to the apparatus.

Preferably, the water resistance surface has a dynamic surface area such that a transverse load onto the water resistance surface changes the surface area of the water resistance surface.

A challenge in building an apparatus for converting energy from waves is that 1t has to be able to work efficiently in calm water conditions and cope with and survive stormy water conditions . In the prior art, multiple solutions have been provided. In the present invention, the water resistance surface is made dynamic meaning that the surface area changes then the load onto the surface increases. As described above, the water resistance surface catches the forward and backward movement of the water thereby forcing the apparatus to move along with this water movement. By making the surface area dynamic. in stormy water conditions, the water tends to push hard against the water resistance surface. As a result, the water resistant surface area becomes smaller and/or more hydrodynamic thereby protecting the apparatus agamst overload. Also, in calm water conditions, the water pushes gently against the water resistance surface. As a result, the water resistant area is large thereby still developing enough power from the movement of the water. The skilled person understands that with the dynamic surface area, varying water conditions can be at least partially normalized.

Preferably. the water resistance surface comprises a flexible sheetlike material and wherein the water resistance surface comprises a frame, wherein the flexible sheetlike material is tensioned within the frame and/or with support of the frame. In one embodiment, the frame is at least partially formed of elastic material enabling a deformation of the frame under load. A deforming frame, even when the surface structure in the frame does not shrink, reduces the projected surface area which is the surface area of the water resistance surface that bears the load.

In such embodiment, the water resistance surface is also considered having a dynamic surface area.

In another embodiment, the flexible sheetlike material is mounted to the frame via elastic connectors allowing deformation of the flexible sheetlike material relative to the frame. A deformable connection between the frame and the sheetlike material stretched within the frame also results in a dynamic surface area. The skilled person will understand that these embodiments may be combined. 5 Preferably, the flexible sheetlike material comprises multiple segments. Preferably, the multiple segments are interconnected via elastic interconnection means. According to another preferred embodiment, the multiple segments comprise complementary magnets enabling disconnection of the segments upon exertion of a predetermined load. Both elastic interconnection means as well as magnets enabling disconnection of segments result in a dynamic surface area. As an alternative embodiment, instead of magnets any grip and release type mechanism that behaves like magnets may be used, such as compliant mechanisms that deform and then release the hold on the sheet, electromagnets, which can be triggered to release, or a material that breaks on purpose under a max load, making sure this breaks instead of the apparatus.

Alternatively, the dynamic surface could be formed using multiple rigid strips that are each mounted rotateably about their own axis such that in a first angular position, the strips together form a surface that resists the water and in a second angular position, typically about 90 degrees from the first angular position, water is allowed to pass through or between the multiple rigid strips.

These and other aspects and advantages of the present invention will be further clarified by reference to the attached non-limiting figures, in which:

Figure 1 shows a schematic top view of an apparatus according to a first embodiment of the invention;

Figure 2 shows a schematic side view of an apparatus according to another embodiment of the invention;

Figure 3 shows a schematic front view of an apparatus according to yet another embodiment of the invention;

Figure 4 shows a schematic side view of an apparatus according to yet another embodiment of the invention;

Figure 5 shows a perspective view of a water resistance surface according to a first embodiment;

Figure 6 shows a front view and a side view of a water resistance surface according to a second embodiment;

Figure 7 shows a front view of a water resistance surface according to a third embodiment;

Figure 8 shows a further embodiment of an apparatus of the invention;

Figure 9 shows a preferred embodiment of an anchor line guiding means; and

Figure 10 shows a side view of the embodiment of figure 9.

Throughout the figures, like numerals are used to refer to like elements. For efficiency, recurring elements will not be explicitly described for each embodiment.

The parts of the apparatus of the invention are in the figures not necessarily scale displayed.

Figure 1 illustrates an apparatus 1 according to a first embodiment of the invention. The apparatus comprises a main structure with a water resistance surface 2 and, at both sides of the water resistance surface 2, floating means 3. The main structure comprises the water resistance surface 2 and the floating means 3 and interconnects them in any way conceivable by the skilled person. Basic mechanical structures can be used to interconnect these elements. Since these mechanical structures are well known to the skilled person and do not form part of the gist of the invention, these structures are not shown nor explained in detail.

The main structure comprises the water resistance surface 2 and the floating means 3 is constructed such that when the main structure is placed into the water, the water resistance surface 2 extends substantially upright. The water resistance surface 2 has a height and a width. The height of the water resistance surface 2 is measured in the above-mentioned upright direction and the width of the water resistance surface 2 is measured in the laying direction. This orientation of the water resistance surface 2 has as a result that a horizontal water movement substantially perpendicular to, or with a component perpendicular to the water resistance surface 2 will exert a force or load onto the water resistance surface 2. This exerted force will induce a movement of the apparatus 1, which is indicated with arrow 15 in figures 1 and 2. The term water resistance surface 2 is defined as a surface which resists movement of the water through the surface. According to this definition, an open surface such as an open net would not be considered water resistance surface 2 since water can pass through the net without significant resistance. In this context, it is noted that holes may be provided in the water resistance surface 2 and the water resistance surface may be formed as a net as long as the resistance against water moving through the surface is significant. The first intention of the term water resistance surface 2 is not to relate to surface properties such as water repellency since a skilled person can understand that an open net can be made of water repellent material but still would not resist water passing through the open net. A water resistance surface 2 as defined in this text may or may not be water repellent.

The floating means 3 are formed of materials that are suitable for floating in water, particularly sea water. In an example, the floating means 3 are made entirely from a plastic foam- like material, or from a closed air-holding vessel. In the shown embodiments, the floating means 3 are formed by two separate elements, each element extending at a different side of the water resistance surface 2. In another embodiment, not shown, a single floating element is provided which is designed to be located with one part at one end and with another part at the other end of the water resistance surface 2. Such single floating element will also be considered as floating means arranged at both sides of the water resistance surface.

Wave energy in a body of water is characterized by water making a reciprocal horizontal movement. Waves may have other characteristics, but the reciprocal horizontal movement is the primary movement which is captured by the apparatus 1 of the invention to convert into another form of energy. The primary function of the water resistance surface 2 is to catch this reciprocal horizontal movement of the water thereby forcing the apparatus 1 in a corresponding reciprocal movement 15.

The apparatus 1 further comprises anchor lines 5. Anchor lines 5 connect the apparatus 1 to a bottom (not shown) of the body of water. The bottom can be a natural bottom of the body of water, or a frame or anchor structure that is mounted to that bottom.

In the embodiment of figure 1, four anchor lines 5a, 5b, 5c and 5d are provided.

Anchor lines may have different shapes and materials. For example, anchor lines can be formed by metal chains. synthetic ropes, flat bands or combinations thereof. In one embodiment, the section of the anchor line which is connected to the bottom of the body of water is formed by a chain whereas the section of the anchor line which is connected to the apparatus is formed by a rope or flat band. The skilled person can determine which anchor line is suitable depending on the specific circumstances. The connection of anchor lines 5 with the bottom (not shown) is formed in a conventional manner. Pins, poles, drag embedment anchors and other foundation structures can be placed in the bottom substrate, or anchors that remain on the bottom due to their weight can be used.

A first set of two anchor lines 5a, Sb extend to one end of the water resistance surface 2, being the left end in the figure 1, while a second set of two anchor lines 5c, 5d extend to another end of the water resistance surface 2. being the right end in figure 1. The skilled person understands that other configurations with less or more than four anchor lines are possible. In one embodiment, not shown, a single anchor line is provided, connected at both ends to the bottom of the body of water and connected to the apparatus 1 in a central zone. When the apparatus reciprocally moves in the water, the anchor line will move through or along the apparatus in such a manner that part of the anchor line that is taken at one side of the water resistance surface 2, will substantially be given at the other side. This movement of the anchor line 5 relative to the apparatus is captured and converted into another form of energy as will be described hereunder in more detail.

The apparatus comprises anchor line holding means 6. In the shown embodiment, the anchor line holding means 6 are formed as rotation means 6. The anchor lines 5 and rotation means 6 are compatible allowing the rotation means 6 to roll up and unroll the anchor lines 5 onto and from the rotation means 6. In particular, the rolling up direction of the first set of anchor lines

Sa and 5b is opposite to the rolling up direction of the second set of anchor lines 5c and 5d. The sections onto which each of the anchor lines 5 is rolled up, are interconnected onto a single shaft.

This has as a result that when the first set of anchor lines 3a, 5b is rolled up, the second set of anchor lines 5c, 5d is unrolled and vise versa. When the apparatus | would reciprocally move in the water, the rotation means 6 will rotate alternatingly clockwise and counterclockwise, which alternating rotation can be transferred to a conversion means 7.

When working with flat ropes and multiple sections on the rotation means are used for rolling up and unrolling ropes from different sets of anchor lines, following effect is obtained.

When a large horizontal movement is made, one section will be substantially uncoiled while the other section will be substantially coiled, creating a difference in diameter of the coils. The tension on the anchor lines, as a result of the buoyant force, is substantially equal, but the diameter of the coils are not equal. As a result, a torque is exerted on the rotation means 6 that forces the apparatus towards a central position with respect to the anchor lines, so that drift of the apparatus towards an anchor line end is limited. A pretension on the anchor lines in the neutral position of the apparatus

I5 is preferred.

The conversion means 7 may be formed as a generator. The generator implements a resistance against the rotation of the rotation means 6, and in that manner energy can be caught.

The skilled person understands how electric energy can be generated in such a context. Figure 1 illustrates how a power chord 8 may be provided to connect the apparatus 1 to an electric power end. It will be clear for the skilled person that the conversion means 7 could also convert to other forms of usable energy such as pressurized gas or liquid, heat, chemical energy, hydrogen, desalinized water and the like.

In another embodiment, not shown, the anchor line holding means 6 are formed as moveable connector, which is able to move transverse to the water resistance surface 2. In such embodiment, the conversion means may be formed as an actuator which is actuated by the moveable connector. Such actuator may in this way generate hydraulic energy, which may be directly used. stored or converted into another form of energy. The skilled person understands that different solutions exist for extracting energy out of a reciprocal movement and converting this energy into another form of energy.

The anchor lines 3 are guided, between the anchor line holding means and the bottom of the body of water, by anchor line guiding means 9. The anchor line guiding means 9 form part of the apparatus 1 and serve in a preferred embodiment multiple purposes. A first purpose is to guide the anchor lines 5 towards the anchor line holding means 6. This also means to route the anchor lines 5 around the floating means, depending on how the floating means 3 are shaped. Figure 2 shows an example of how the anchor line guiding means 9 route the anchor lines 5 around the floating means 3. The skilled person understands that in another embodiment, floating means 3 are shaped to allow a substantially straight passing of the anchor lines 5 so that this functionality of the anchor line guiding means 9 is unnecessary.

A second purpose of the anchor ling guiding means 9 is to allow the apparatus to rotate relative to the bottom of the body of water, such that the anchor lines 5 approach the apparatus from a different angle, while enabling an optimal connection to the anchor line holding means 6. Particularly when the anchor line holding means 6 are formed as rotation means, it is advantageous when the anchor lines 5 approach the rotation means substantially perpendicular to the rotation axis since this facilitates a straight rolling and unrolling onto/from the rotation means.

The anchor ling guiding means 9 are, for its second purpose, preferably hingeably connected to the apparatus 1. In the embodiments of figures 1 and 2, the anchor line guiding means 9 are connected to the apparatus | via flexible interconnection elements 13. Examples of flexible interconnection elements 13 are ropes, chains, bands and the like. Due to their flexibility, the anchor line guiding means 9 can hinge relative to the apparatus 1. This hinging of the anchor line guiding means 9 enables the latter to take the position where the anchor line is optimally guided in a turn around the anchor line guiding means, at one end of the turn the anchor line goes straight to the anchor line holding means 6 and at the other end of the turn the anchor line goes straight to the bottom of the water.

In an alternative preferred embodiment, each roller comprises a pair of rollers. The pair of rollers are preferably shaped complementary, more preferably as a combination of a convex and a concave roller. The pair of rollers is preferably mounted to the main structure via an upright rotational shaft such that the pair of rollers can rotate relative to the main structure. An alternative anchor line guiding means 9 is described hereunder with reference to the figures 9 and 10.

A third purpose of the anchor line guiding means 9 is to induce a counter-rotation when the apparatus rotates in the body of water out of its optimal angular position. The optimal angular position is the position where the anchor line, considered in the top view, runs in a straight line from a first anchoring point at the bottom of the body of water, through the apparatus 1, to a second anchoring point at the bottom of the body of water. In this angular position of the apparatus 1, the anchor line, considered in the top view, extends perpendicular to the water resistance surface 2. Any rotation of the apparatus 1 away from this optimal angular position reduces the efficiency of the apparatus 1.

A main factor influencing the effect of the third purpose induced by the anchor line guiding means 9 on the apparatus is the distance between the anchor line guiding means 9 and the water resistance surface. In this context, the distance between the anchor line guiding means 9 and the water resistance surface is defined as the perpendicular distance between the plane in which the water resistance surface extends in a neutral state. A neutral state is a state wherein no extemal forces or loads are applied to the water resistance surface causing a deformation of the latter.

The anchor line guiding means 9 of the embodiments of figure 1 and figure 2 are held at a distance from the water resistance surface 2 by means of the flexible interconnection elements 13. The skilled person understands that in the shown embodiments, the distance depends on a combination of multiple factors including the length of the anchor lines 5, the height of the apparatus 1 relative to the bottom of the body of water, the buoyant force and the length of the flexible interconnection elements 13.

Figure 1 illustrates how the distance between the anchor ling guiding means 9 and the water resistance surface 2 induces a counter-rotation, also known as a yaw rotation of the apparatus. At both sides of the water resistance surface 2, the anchor lines apply a pulling force to the apparatus. These pulling forces are indicated with arrows with reference numbers 11. When these pulling forces are equal, no translational resulting force acts on the apparatus 1 as a result of these pulling forces. However, when these pulling forces are not aligned, as is the case in the shown embodiment, a rotational force is induced onto the apparatus which is illustrated with arrow 12, also known as a yaw rotation. This rotational force induces the apparatus 1 to rotate towards its optimal rotational position. In figure 1, the anchor line guiding means 9 are located at a distance that is greater than the distance between the furthest part of the floating means 3 from the water resistance surface 2. In other embodiments, as is shown in the other figures, this distance is smaller. Preferably, this distance is larger than 10cm, more preferably, this distance is larger than 10% of the width of the water resistance surface 2, even more preferably, this distance is larger than 20% of the width of the water resistance surface 2, most preferably, this distance is larger than 30% of the width of the water resistance surface 2.

In the claims, the position of the anchor line guiding means 9 relative to the water resistance surface is defined as: when in use, such that a perpendicular projection of each anchor line guiding means onto a plane wherein the water resistance surface extends lays in a central upright area of said plane and wherein each anchor line guiding means is located at a distance from the water resistance surface. It is evident that “in use’ means in normal operational use of the apparatus 1 and that any abuse or abnormal use of the apparatus 1 is excluded. Examples of normal operation use of the apparatus 1 are illustrated in the figures. The plane wherein the water resistance surface extends is explained above in relation to its neutral state. The perpendicular projection of the anchor line guiding means 9 lays in a central upright area 10. Figure 7 shows the central upright area 10 on an embodiment of the water resistance surface 2. The term central in the expression ‘central upright area’ relates to the horizontal position of the area relative to the apparatus, the water resistance surface and the plane. Because the area is central, it is located in the middle of the apparatus. This means, considering the total length of the apparatus, determined by or at least related to the width of the water resistance surface, that the area spans maximum 1/3 of the total length of the apparatus, preferably maximum 1/4 of the total length of the apparatus,

more preferably maximum 1/5 of the total length of the apparatus and most preferably maximum 1/6 of the total length of the apparatus. The term upright in the expression “central upright area’ relates to the direction in which the area extends, which is the upright direction. In other words, it is less relevant at which height the projection of the anchor line guiding means 9 is located since the area is upright and the projection has to be in the area. Furthermore, since the plane in which the water resistance surface extends is larger, since it is imaginary, than the water resistance surface itself, the projection does not necessarily fall within the water resistance surface, but may fall above or below this surface within the upright area. An example thereof is shown in figure 4.

To further improve the operation of the apparatus 1, the majority of parts of the apparatus 1 is symmetrical about an upright plane transverse to the water resistance surface 2. In particular, the water resistance surface 2, floating means 3, anchor line holding means 6, anchor line guiding means 9 and flexible interconnection elements 13 are symmetrical about an upright plane transverse to the water resistance surface 2. This is shown in figure 1 and 3. In figure 3. the symmetry plane is illustrated with reference number 20.

In figure 1, two possibilities are shown to practically connect multiple anchor line guiding means 9 at each side of the water resistance surface 2. In the possibility shown on the left side of the figure, the anchor line guiding means 9a are formed as a single block wherein multiple anchor lines 3a, 5b can be guided. This single block is connected via flexible interconnection clements 13 to the apparatus 1. The angular orientation of the single block serves and routs the two anchor lines 5a and 5b. In the possibility shown on the right side of the figure, the anchor line guiding means 9b, 9c are formed as separate blocks each guiding a single respective anchor line 5e, 5d. These separate blocks are each individually connected via flexible interconnection elements 13 to the apparatus 1. The angular orientation of each separate block depends on the direction of that particular anchor line and serves and routs that single anchor line.

During normal operation of the apparatus 1, when waves in the body of water act on the water resistance surface 2, the apparatus 1 is moved reciprocally as illustrated with arrow 15. Anchor lines are, as explained above, connected to a bottom of the body of water. As a result, anchor lines, in contrast to the apparatus. do not reciprocally move in the water but the anchor lines remain stationary. As a result of this reciprocal movement of the apparatus and the anchor lines being stationary, in the embodiment of the figures, the anchor lines 5 extending at one end of the water resistance surface 2 will roll up while the anchor lines extending at the other end of the water resistance surface 2 will unroll and vice versa. This movement of the anchor lines relative to the apparatus 1 is facilitated by providing the anchor line guiding means 9 with rollers 14. As explained above, this rolling and unrolling of the anchor lines on/from the rotation means 6 may be resisted by the conversion means to extract energy from the movement.

Figure 2 shows a schematic side view of the apparatus of the invention 3. The explanation above is analogue for the embodiment shown in figure 2. This figure shows that the floating means 3 keep the apparatus 1 floating onto the water surface 4 of the body of water.

Because the floating means 3 are located at both sides of the water resistance surface 2, the floating means 3 keep the water resistance surface 2 upright in the water. Figure 2 also shows that the center of gravity of the apparatus 1, due to the water resistance surface 2 extending downward from the floating means 3, is located below the floating means 3 such that, even when waves act against the water resistance surface 2, the apparatus tends to bring itself into the upright position meaning the position wherein the water resistance surface 2 extends upright. The device will still stay upright if the center of gravity is above the center of buoyancy, because of the floaters are placed horizontally apart.

Figure 2 illustrates how the anchor line holding means 6 and the conversion means 7, not shown in figure 2 but located adjacent to and connected to the anchor line holding means, are arranged above the water resistance surface 2. When the apparatus 1 is floating, as in the illustrated embodiment, the anchor line holding means 6 and the conversion means 7 are preferably situated above the water surface 4. This however is not necessary and anchor line holding means 6 and the conversion means 7 could be located under the water line. The anchor line guiding means 9 comprise rollers 14. The position of the anchor line guiding means 9 is such that the anchor lines 5 are routed from the anchor line holding means 6, underneath the floating means 3, towards anchor point (not shown) located at the bottom of the body of water. The distance between the anchor points (not shown) located at the bottom of the body of water is preferably at least 10 times the width of the water resistance surface 2, more preferably at least 15 times the width of the water resistance surface 2, most preferably at least 20 times the width of the water resistance surface 2.

Alternatively or additionally, the distance between anchor points is preferably more than 6 times the water depth and up to 14 times the water depth. The weight of the anchor lines 5 as well as the tension on the anchor lines 5 pull the apparatus 1 downward in the body of water. Figure 2 shows that the anchor lines 5, and therefore also the anchor line forces, are directed slightly downward since the anchor lines 5 go to anchor points at the bottom of the body of water. The buovant force of the floating means 3 keep the apparatus 1 floating. This interaction creates a tension on the anchor lines 5 which can be used to keep the apparatus in or close to its optimal angular position, as is explained above. Figure 2 also illustrates how this tension on the anchor lines 5 keep the anchor line guiding means 9. when they are connected to the apparatus via flexible interconnection elements 13, in the operational position.

Based on figure 2, the skilled person is able to deduce how a reciprocal movement 15 of the apparatus would induce a rolling and unrolling of the anchor lines 5 onto/from the rotation means 6. As explained above, this can be converted into another form of energy, for example electric energy.

Figure 3 illustrates a front view of an apparatus 1 of a further embodiment of the invention. In the figure, floating means are omitted for clarity purposes since they would obstruct the view of the majority of elements shown. Furthermore, anchor lines and elements acting thereupon are only drawn on one side of the water resistance surface 2 to reduce the complexity of the figure. The skilled person understands that technical principles are shown and will have no problems applying these principles in an apparatus of the invention.

In figure 3, the water resistance surface 2 is tensioned in a frame 16. The options and embodiments to construct the water resistance surface 2 will be further explained hereunder. In figure 3, the frame 16 is integrally formed with the main structure of the apparatus |. Elements such as the anchor ling holding means 6, the conversion means 7 as well as the anchor line guiding means are connected, directly or indirectly, to the main structure.

Figure 3 shows an embodiment wherein the water resistance surface 2 is only formed at a bottom part of the apparatus and wherein the anchor line guiding means 9 are arranged at a height which is above the water resistance surface 2. In this embodiment, when a perpendicular projection would be made of the anchor line guiding means 9 onto the plane including the water resistance surface, this projection would be located above the water resistance surface 2. The same is true for the embodiment of figure 4.

The anchor line guiding means 9 are connected to an upper beam of the frame 16.

The anchor line guiding means may be connected to the apparatus via a hinge with a substantially upright hinging axis. Alternatively, the anchor line guiding means 9 may be connected to the apparatus via a ball hinge. The hinge or ball hinge may be connected directly to the frame 16 or may be connected on an arm as illustrated in figure 4. Further alternatively, the anchor line guiding means 9 may be connected to the apparatus via a flexible interconnection element. In this embodiment, which is different from the embodiment shown in figures 1 and 2, the length of the flexible interconnection element is considerably shorter such that the distance between the anchor line guiding means 9 and the plane in which the water resistance surface 2 extends is rather small.

As explained above, however, this distance is preferably at least 10 cm and more preferably at least 10% of the width of the water resistance surface 2.

Figure 4 illustrates another embodiment of the invention. In figure 4, compared to the embodiments of figures 1, 2 and 3, the rolling direction of the anchor lines onto the rotation means 6 is reversed so that the anchor lines cross the center of the apparatus before rolling onto the rolling means 6. This setup allows a more compact construction of the apparatus 1. It also allows fora less steep angle between anchor line guiding means 9 and anchor line holding means 6, which reduces wear on the anchor line 5. Figure 4 shows that in such configuration, the anchor lines 5 remain further away from the floating means compared to, for example, the embodiment in figure 2.

Figure 4 further shows that the anchor line guiding means 9 are connected above the water resistance surface 2 and at a distance of the plane wherein the water resistance surface 2 extends. In the embodiment of figure 4, the anchor line guiding means 9 are arranged on an arm extending from the central part of the main structure of the apparatus 1. In the shown embodiment, the arm is rather short, however the arm could alternatively be significantly longer and extend for example further outward than the floating means 3. In the shown embodiment, the arm is connected to the upper beam of the frame of the water resistance surface 2. However alternatively, the arm could be mounted to other parts of the main structure of the apparatus, for example close to the anchor line holding means 6.In yet another example. not shown, the anchor line guiding means 9 are connected to or integrated in the floating means 3.

Figures 5, 6 and 7 relate to the aspect of the apparatus where the surface area of the water resistance surface 2 is dynamic. Figures 5, 6 and 7 show different embodiments and examples to obtain such dynamic surface area. A dynamic surface area is defined as a surface area that changes under influence of external load. More specifically and preferably, a dynamic surface area is defined as a surface area that becomes smaller when external load increases and that returns to its original size when external load decreases to zero. In this context, the surface area does not need to gradually change nor should there be a constant in the change.

In figure 3, the water resistance surface 2 comprises a frame 16 in which a flexible sheetlike material 17 is stretched. Examples of flexible sheetlike material are plastic sheeting, fabric, fiberglass cloth and the like. These materials can be coated to make them water impermeable or to give other characteristics. Flexible sheetlike material does not require the material to be stretcheable, but to be flexible meaning it can be rolled and/or folded.

The flexible sheetlike material in figure 5 comprises two segments 17a and 17b.

The flexible sheetlike material is preferably connected to the frame using elastic connectors 18.

The elastic connector 18 will tend to stretch when load is applied to the flexible sheetlike material 17 such that the frontal surface of the flexible sheetlike material becomes smaller when load is increased. This is a first embodiment of a dynamic surface area. The skilled person understands that it is not required to have two segments for this effect to arise. The skilled person also understands that more than two segments can be provided to further increase the effect of the surface area reduction under load. In this context, the elastic connector between the segments of the flexible sheetlike material. indicated with reference number 18°, may be of different type than the elastic connector 18 between the frame 16 and the flexible sheetlike material 17.

Figure 6 shows another example of a water resistance surface 2 with a dynamic surface area. Figure 6a shows a front view while figure 6b shows a side view of the water resistance surface 2 under load. In the embodiment of figure 6, the frame elements 16 are bendable or elastic. This is schematically illustrated with taper-shaped frame elements illustrating that the bendability increases towards the tip of the frame element. The skilled person understands that there are many ways to implement this in a practical situation which may look totally different from what is illustrated in figure 6. For example, the skilled person may form a frame with rigid frame elements interconnected with bendable connectors such as springs.

Figure 6 shows how the flexible sheetlike material 17 1s firmly connected to the frame elements. In the figure, the lower end of the flexible sheetlike material 17 is a free end. In another embodiment, a frame part is provided to support and hold the lower end of the flexible sheetlike material 17. When the frame bends, as illustrated in figure 6b, the frontal surface area decreases, which is also considered to be a smaller surface area hence a dynamic surface area.

Figure 7 shows vet another embodiment of a water resistance surface 2 with a dynamic surface area. Figure 7 shows, similar to the embodiment of figure 5, a flexible sheetlike material 17 having two segments 17a and 17b, which segments are stretched in a frame 16. The two segments 17a and 17b each have a border side with which they lay against each other. At the border sides of the two segments 17a and 17b, complementary magnets are provided. One advantage of working with magnets in this context is that the magnetic pull force, also known as the releasing force of the magnets, is known in advance such that it is easy to determine in advance at which external load a magnet is to release. The skilled person understands from the figure and the explanation above that the magnets can be selected such that, when a predetermined external load is applied to the water resistance surface 2, one or more magnets are released to reduce the surface area of the water resistance surface 2. The magnets are illustrated with reference number 19 and 19°.

The skilled person understands that technical elements from the embodiments of figures 5, 6 and 7 may be combined. Alternatively, not shown, an actuator may be provided to control the surface area of the water resistance surface 2.

Figure 8 illustrates an embodiment where two apparatuses 1 as described above are interconnected via a further water resistance surface 21. The further water resistance surface 21 is formed in a similar manner as the water resistance surface 2 of the apparatus 1. The further water resistance surface 21 comprises a further frame 22 in which a further sheetlike material 24 is stretched. The further frame 22 keeps the two apparatuses at a predetermined distance from one another. The embodiment of figure 8 allows to use the apparatus of the invention in an environment where the wave energy is low. By providing two apparatuses and interconnecting them with a further water resistance surface 21, the total surface area of the water resistance surfaces 2 of the apparatuses and the further water resistance surface allows to generate a significant amount of energy even in waves with low energy.

The embodiment of figure 8 should not be perceived as a single apparatus where the anchor line guiding means are not located, when in use, such that a perpendicular projection of each anchor line guiding means onto a plane wherein the water resistance surface extends lays in a central upright area. The embodiment of figure 8 should on the other hand be correctly perceived as two apparatus, where in each apparatus the anchor line guiding means are located, when in use, such that a perpendicular projection of each anchor line guiding means onto a plane wherein the water resistance surface extends lays in a central upright area. According to the correct perception, the embodiment of figure 8 does fall under the scope of the present claim. Even when the further frame elements 23 would be omitted and the flexible sheetlike material 17 and the further flexible sheetlike material 24 would be formed in one piece. still such perception can be maintained. In this manner, the apparatus 1 of the invention may be used separately or as building element in a larger construction.

Figure 9 shows a perspective view of a preferred embodiment of an anchor line guiding means © with the roller 14. Figure 10 shows a side view of the embodiment of figure 9. In the embodiment of figure 9, each anchor line guiding means 9 comprises a pair of rollers 14a and 14b. The pair of rollers 14a and 14b are held in a relative position with respect to each other using a roller frame 25. The roller frame 25 is connected to the main structure of the apparatus via an upright shaft 26, allowing the pair of rollers 14a, 14b to rotate relative to the main structure about the upright shaft 26. The pair of rollers comprises a distal roller 14a and a proximal roller 14b. The distal roller 14a is preferably concave and the proximal roller 14b is preferably convex. The shapes of the pair of rollers 14 is preferably complementary. The distal roller 14a is preferably located lower and further away from the main structure compared to the proximal roller 14b. The lower end of the proximal roller 14b is preferably located below the upper end of the distal roller 14a such that an anchor line coming from the bottom of the body of water is forced to extend at least partly downward after passing the distal roller 14a, before extending upward after the proximal roller 14b. Tests and simulations have shown that providing a convex and concave roller in the shown and described setup has a surprisingly positive effect on the guiding of the anchor lines.

In all embodiments, the dynamic surface area ensures that overload of the apparatus 1 is avoided, namely when the energy of the waves is too high, for example in stormy weather, the surface area decreases so that the effect of the waves on the apparatus is not proportional to the energy of the waves.

Although the invention has been described hereinabove with reference to particular exemplary embodiments, these embodiments should be considered to illustrate the invention, and not to limit it. The scope of the invention is determined by the attached claims and their equivalents, as appropriately interpreted in the light of the description.

Claims (15)

Conclusions 1. Device for converting energy from waves in a body of water. the apparatus comprising a main structure having a water drag surface having a height and a width, said width substantially defining the length of the main structure, the main structure further comprising buoyancy means provided on either side of the water drag surface to enable the main structure to float on the water with the water drag surface in a substantially upright position, the apparatus further comprising an anchor line extending on either side of the water drag surface, the anchor line being adapted, on either side of the water drag surface, to be anchored to a bottom of the body of water and the anchor line being connected to anchor line retaining means provided on the main structure, the main structure further comprising conversion means connected to the anchor line retaining means and adapted to convert a movement of the anchor line retaining means into another form of energy, the main structure further comprising anchor line guide means provided on either side of the water drag surface, each of the anchor line guide means being positioned, when in use, so that a perpendicular projection of each of the anchor line guide means onto a plane in which the water resistance surface extends lies in a central upward region of said plane and each of the anchor line guide means is spaced from said plane. 2. Apparatus according to the preceding claim, wherein each of the anchor line guide means comprises a roller for guiding the corresponding anchor line. Apparatus according to any one of the preceding claims, wherein each of the anchor line guide means is pivotally attached to the main structure to allow rotation of the anchor line guide means relative to the main structure. 4. Apparatus according to any preceding claim, wherein each of the anchor line guide means is attached to the main structure via a flexible connecting element. 5. Apparatus according to any one of the preceding claims, wherein each roller of the anchor line guide means is at a height below the anchor line holding means and preferably at a height below the floating means. 6. A device according to any preceding claim, wherein the anchor line comprises a first set of anchor lines extending on one side of the water resistance surface and a second set of anchor lines extending on another side of the water resistance surface. 7. Apparatus according to the preceding claim, wherein the anchor line holding means comprise rotation means and wherein each of the anchor lines of the first set and the second set are arranged to be rolled up and unrolled from the rotation means. 8. Device according to the preceding claim, wherein the rotation means comprise a rotation segment for each anchor line. 9. Device according to the preceding claim, wherein the rotation segments are connected to a single rotation axis. 10. Apparatus according to any one of the preceding claims 6 to 9, wherein the first set of anchor lines comprises at least two anchor lines and wherein the second set of anchor lines comprises at least two anchor lines. Device according to any of the preceding claims, wherein the anchor line retaining means and the conversion means lie above the water resistance surface. 12. Apparatus according to any one of the preceding claims, wherein the combination of the water resistance surface and the anchor line holding means are symmetrical about an upward plane transverse to the water resistance surface. Device according to any of the preceding claims, wherein the water resistance surface has a dynamic surface such that a transverse load on the water resistance surface changes the surface area of the water resistance surface. 14. Device according to the preceding claim, wherein the water resistance surface comprises a flexible sheet-like material and wherein the water resistance surface comprises a frame, wherein the flexible sheet-like material is tensioned in the frame. 15. The device of the preceding claim, wherein the flexible sheet-like material comprises a plurality of segments.