Arrangement for converting energy of water waves into rotational motion

Abstract

An arrangement for converting the energy of wa¬ ter waves into rotational motion, comprising a body (2) arranged to roll in accordance with the motion of the water waves, at least one elongated rotator shaft (3), which is supported on the body (2) to rotate around its longitudinal axis (L). Two rotator elements (4, 5) are arranged on the rotator shaft (3), which are located in the longitudinal direction of the rotator shaft (3) at a distance from each other and their centers of gravity being located on opposite sides of the longitudinal axis (L) in relation to the direction of rotation of the rotator shaft (3). The rotator shaft (3) is oriented in the direction of its longitudinal axis (L) on average parallel to the vertical plane passing through the direction of the motion of propagation (W) of water waves. The rotator shaft (3) swings back and forth with the body (2) on the vertical plane on average passing through the direction of the motion of propagation (W) of water waves. The swinging of the rotator shaft (3) forces the rotation of the centers of gravity of the rotator elements (4, 5) around the rotator shaft (3).

Description

[0001] Arrangement for converting energy of water waves into rotational motion

[0002] The object of the invention is an arrangement for converting the energy of water waves into rotational motion, comprising a body arranged to roll ac- cording to the movement of water waves, an etongated rotator shaft, which is supported on the body to rotate around its longitudinal axis.

[0003] The problem with well-known wave power plants in particular is the irregular motion of the waves, the variation in the size of the waves and wave period. It has been difficult to transform this reciprocating motion into a rotational motion or other motion with high efficiency. Such a wave power plant is known, for example, from publication US 4,266,143.

[0004] Often also the functional parts of such systems are in direct contact with the swell itself, usually beneath the surface, creating a significant disadvantage, for example corrosion. This leads to rapid wear of components and further frequent maintenance procedures.

[0005] To some extent, attempts to reduce these problems have been made, for example, with the solution according to reference publication FI 122615 B related to a wave power plant, where a gyration shaft connected to the body is arranged to rotate by means of devices arranged around the power plant body and create a gyratory motion of the body. Achieving a gyratory motion, however, requires a moderately complex structure, and the rotational motion achieved in this way is not very effective in terms of power generation and uniformity.

[0006] The problem with both of these prior art technologies is the imbalance result- ing from the moving single mass (for example, the rotator 6 shown in FI 122615 B) of the arrangement. This leads to problems especially at shallow waves, because the individual weights (masses) that may tilt the body re- quire a relatively large force to initiate rotation, which will not be provided by shallow waves.

[0007] The object of the invention is to provide a new type of arrangement in which the aforementioned problems have been eliminated or substantially reduced so that the reciprocating motion of waves can be converted directly into a continuous rotational motion.

[0008] This object is achieved by the invention based on the characteristics dis- closed in the attached claim 1.

[0009] Preferred embodiments of the invention are disclosed in the dependent claims. They show embodiments in which the arrangement according to the body and rotator shaft is applied to be placed directly in the swell and as part of the wave power plant.

[0010] The basic idea of the invention is to bring a body equipped with a rotator shaft, which is novel to the prior art, into a rolling motion in accordance with water waves, which in turn puts the rotator shaft into a rotating motion. This solution avoids the prior art disadvantages, where the components producing motion are in contact or at least exposed to waves, in most cases sea water. The arrangement according to the invention can also be applied in such a way that the body with its rotor shafts can be placed, for example, in the interior of a watercraft (boat or ship), for example on a deck or floor, where the body moves according to the movement of water waves. In addition, complex structures according to the prior art are avoided, because the rotor shaft according to the invention only requires a reciprocating motion in the plane of the propagation of the water waves to rotate, and for example, means for gyratory motion are not separately needed. With the arrangement according to the invention, an arrangement functioning with good efficiency is achieved, in which the rotational motion of the rotator shaft is implement- ed efficiently and uniformly even with a slight movement of water waves or at a small wave height. With the arrangement according to the invention, a constantly balanced body is also achieved, because the rotator elements are arranged in such a way that no imbalance according to the prior art is able to take place. In this case, rotation of the rotator shaft is also effected in shal- low waves.

[0011] It is also possible to use the rotator system according to the invention in a gyrating device. In this case, the rotator shaft is placed essentially parallel to the gyration axis.

[0012] In the following, the invention is illustrated with the help of exemplary em- bodiments by referring to the attached drawing, in which

[0013] Figure 1 schematically shows an arrangement according to one preferred embodiment of the invention for half of the body part, and

[0014] Figure 2 schematically shows an arrangement according to another pre- ferred embodiment of the invention.

[0015] Accordingly, shown in Figure 1 is an arrangement according to a preferred embodiment of the invention, where the energy of water waves is converted into rotational motion. Here, the arrangement includes body 2 intended to float along with the water waves, of which body approximately half is thus shown in the longitudinal direction of body 2. Body 2 thus forms a float or pontoon, on which the other elements belonging to the arrangement can be placed in the manner shown below. By way of example, the average water plane (i.e. not the surface of the wave) is marked in Figure 1 with reference A. Instead of water, body 2 can be placed inside a vessel (boat, ship) on the water, however, in such a way that the operating conditions described below are fulfilled. Rotator shaft 3 is supported on body 2. In the embodiment according to Fig- ure 1, there is one rotator shaft 3 arranged in support 6, which is arranged to be immovable with respect to the outer jacket of body 2 and is thus part of the body. Here, rotator shaft 3 and support 6 are located in the center of body 2 in the longitudinal direction of the body. As such, support 6 can form a frame, which can, for example, be placed on a platform arranged in a ship to swing according to the movement of the water waves.

[0016] The arrangement according to the invention can comprise also several rota- tor shafts 3 and supports 6 placed at a distance from each other along the length of body 2. For example, body 2, which is 50 meters long, can have 2 to 10 rotator shafts 3 per body.

[0017] Arranged in support 6 are bearings 6a, 6b, 6c and 6d or similar support ele- ments, the number thereof here being four. The number of these can vary as needed. Rotator shaft 3 is arranged on these bearings 6a, 6b, 6c and 6d to rotate around its longitudinal axis L. This rotation is illustrated with double arrow R. Rotator shaft 3 can therefore rotate in either direction. Support 6 is arranged in space S delimited by the outer jacket of body 2, whereby rotator shaft 3, support 6 and all other associated functional components are sepa- rated from the water forming the waves and the unfavorable effects caused thereby, such as corrosion.

[0018] Two rotator elements 4 and 5 are arranged on the rotator shaft 3 according to the invention, which are located at a distance from each other in the lon- gitudinal direction of rotator shaft 3 (in the direction of longitudinal axis L). They are placed on the outer circumference of rotator shaft 3 in such a way that their centers of gravity are located in respect of the direction of rotation of rotator shaft 3, i.e. in the direction of the circumference of rotator shaft 3, on opposite sides of the longitudinal axis L. The shape of rotator element 4 and 5 can be chosen according to the purpose, having regard to, for exam- ple, the surrounding space and their desired mass. Shown in Figure 1 are rotator elements 4 and 5, which form a fan-like widening part on the circum- ference of rotator shaft 3. Consequently, their centers of gravity are located in the radial direction of rotator shaft 3 outside the rotator shaft and on op- posite sides of the longitudinal axis L. There can be several rotator elements per rotor shaft, in any case an even number so that the position of the final center of gravity is maintained as mentioned above. With several rotator el- ements, if desired, the eccentricity of the shaft can, however, be adjusted by placing part of the rotor element in different positions in relation to the shaft and to each other.

[0019] In the arrangement according to the invention, rotator shaft 3 is directed in the direction of its longitudinal axis L, on average parallel to the vertical plane passing through direction of the motion of propagation W of water waves. In the embodiment according to Figure 1, it is preferred that body 2 is an elongated floating body in a direction transverse to the direction of the motion of propagation W of water waves. The cross-section of the wall of body 2 is preferably oval or substantially oval in shape. However, the part above the water can have a flat surface, for example, to facilitate the move- ment of maintenance personnel. The long axis of the oval is preferably at the height of the water plane (average water plane A) or substantially at that height. Body 2 is thus ideally directed perpendicularly in the transverse direc- tion to the direction of propagation W, but can thus turn to some extent back and forth from this. For example, the turning angle can deviate and vary in respect of the perpendicular transverse direction of propagation W by 1-40 degrees in either direction. Body 2 can also be permanently installed at a somewhat tilted angle, for example 1-40 degrees, whereby the varying hori- zontal suction of the different phases of the wave causes a reciprocating back and forth rotation of the body around the vertical axis. This varying ro- tation acts on the rotator (the shaft must be horizontal in this application) in a manner similar to that of the swaying of the body, contributing to support- ing the rotation and providing energy to the system. In Figure 1, rotator shaft 3 is fitted to body 2 so that the nominal direction of its longitudinal axis L is horizontal, i.e. in the direction of the average water plane A. In this case, rotator shaft 3 swings back and forth on both sides of the horizontal plane along with body 2, on average in the vertical plane pass- ing through the direction of propagation of the water waves. The extent of this reciprocating motion depends on the height and amplitude of the water waves. As a result, the rotator elements 4 and 5, with the above disclosed location of their centers of gravity as a prerequisite, acquire a "pulsatingly" accelerating rotary motion R with the waves around longitudinal axis L of rotator shaft 3, applying a turning torque to rotator shaft 3. This arrange- ment enables the alternative placing of rotator shaft 3 in body 2 so that it swings back and forth with body 2 with the nominal direction in the vertical direction or in a direction that is between the horizontal direction and the vertical direction in the average vertical plane passing through the direction of the motion of propagation W of water waves.

[0020] It is preferred that body 2 is anchored in place with the intended anchoring or fastening means 2a, 2a'. Anchoring means 2a, 2a' are preferably anchor- ing chains or ropes 2a or the like, which are attached from the top to at- tachment points 2a' arranged in the rear part 2' of the body. The rear part 2' of the body refers to the part of body 2 that is behind the direction of the motion of propagation W of water waves. Consequently, the front part 2" of the body refers to the part of body 2 that is towards the direction of the mo- tion of propagation W of water waves. In other words, the water waves mov- ing in the direction of propagation W will first hit the front part 2" of the body. The anchoring chains or ropes or the like 2a are attached at their low- er end to the seabed or to another fixed platform arranged therein (not shown). The anchoring means 2a, 2a' arranged in this way enable the recip- rocating rolling movement of body 2 (indicated by the double arrow R2) in a controlled manner and thus a controlled or at least significantly more con- trolled rotation of rotator elements 4 and 5 or the phase angle, the position of centers of gravity and acceleration (and rotation speed) in respect of the characteristics of the waves, such as amplitude and height. Such an anchor- ing arrangement contributes to increasing the energy production of the sys- tem. Anchoring means 2a can preferably be adjusted according to the pre- vailing conditions so that rotator shaft 3 according to the arrangement will rotate optimally.

[0021] In addition to this, other types of arrangements can be implemented in this kind of hollow body 2, allowing an adaptation of the arrangement according to the invention to factors changing in the environment, mainly to the above- mentioned characteristics of the waves. One such arrangement is additional tanks 2b, 2b* arranged on the inside, outside and / or part of the outer shell of body 2, which can be filled with water. In addition to or instead of this, addi- tional tanks 2b, 2b' can be permanently filled with water, in which case it is possible to transfer water between the additional tanks. In addition to their task of changing the weight of body 2 and of this arrangement in general, the additional containers 2b are placed in such positions of body 2 where they can influence the distribution of the added weight within body 2. By adjusting the weight distribution in this way, it is also possible to influence the tilt angle of body 2, i.e. the angle at which body 2, and thus also rotator shaft 3, is tilted from the horizontal plane, for example in relation to the wa- ter plane of calm water or the direction of the motion of propagation (W) of water waves. In other words, this serves to affect the angle at which (on average) the rotator shaft 3 is in the vertical plane passing through the direc- tion of the motion of propagation W of water waves.

[0022] This tilt angle and the changed inertia caused by the displacement of the internal mass affect the hydrodynamic properties and characteristic frequen- cy of the body. This is especially true with body shapes where the intersec- tion between the body and the water plane, especially the surface area, changes with different tilt angles of the body. The oval body shape shown in the figures is a preferred example of this. By adjusting the tilt angle in this way, body 2 can be made to resonate with waves of different lengths as needed (changing average amplitude of the waves). The change in the tilt angle of body 2 here serves to affect the length of the body in the direction of wave propagation W, which in turn affects the characteristic frequency of the body and the aforementioned resonance. In other words, by adjusting the tilt angle of body 2, the arrangement according to the invention can be adapted to changing waves in such a way that it resonates with the wave and is thus able to maximize energy production.

[0023] Shown in Figure 1 is only a schematic example of the additional tanks 2b and 2b' located on one side of the support 6. The placement of the additional tanks 2b and 2b* can be implemented in many ways depending on the final size and location of body 2. In Figure 1, an additional tank 2b is arranged in the bottom area of body 2, and an additional tank 2b' is arranged on the side of the body, on the same side as the attachment point of anchoring means 2a. It is, however, important that the additional tank can be filled and emp- tied completely or partially according to the conditions. Water can also be transferred internally from one additional tank to another, as already men- tioned above.

[0024] Shown in Figure 2 is an exemplary embodiment in which several additional containers are arranged in body 2, such as in the rear part 2', front part 2" and upper and lower part of body 2. In this case, the change in the weight of body 2 and / or the above-mentioned tilt angle can be implemented more pre- cisely. Coordination with the anchoring and fastening means 2a, 2a' can also be implemented better. For example, filling the additional tanks of the front part 2" of body 2 with water (partially or completely) acts as a counterbal- ance to the tilting or pulling force that the anchoring and fastening means 2a, 2a' create on body 2. On the other hand, by filling the additional tanks of the upper part and the rear part 2' completely with water, the body's center of gravity can be raised, which slows down the body's characteristic frequen- cy. At the same time, when body 2 tilts towards the rear part 2', the righting arm of body 2 decreases. The body shown in Figure 2 can be formed as a steel structure or made of concrete.

[0025] It is also possible to use weights instead of or in addition to additional tanks, the position of which can be changed in relation to body 2 to achieve a dif- ferent weight distribution on the body. However, in this case, it is not possi- ble to influence the total mass of the arrangement.

[0026] Accordingly, the arrangement implements the rotation of rotator shaft 3 with a smooth and relatively small movement of rotator shaft 3 (which is parallel to the vertical plane passing through the direction of propagation of the mo- tion of the water waves (W)). In other words, the movement of rotator shaft 3 is realized even in a very small motion of water waves. For such an ar- rangement, it is very advantageous to equip the rotator shaft 3 with means for power take-off 7 and to form a wave power plant from the arrangement disclosed above. This is implemented here with generator 7 arranged on the rotator shaft 3 for power take-off. Here, generator 7 is fitted in the longitudi- nal direction L of rotator shaft 3 between rotator elements 4 and 5. Opera- tion of the generator, which is known in itself, is not presented in more detail here. It should, however, be mentioned that here the rotor of the generator is arranged to rotate with rotor shaft 3, and a stator surrounds the rotor of the generator. The stator is equipped with means known per se for transfer- ring the current generated by generator 7 to the desired object and / or for changing the properties as desired.

[0027] The torque of the generator is controlled by means of a special control pro- gram, where the position of the rotator elements (masses) is intended to be constantly brought to an optimal position in relation to the varying accelera- tion, by applying a changing speed target. When the acceleration is at its maximum, the rotator elements (masses) should ideally be located at an an- gle of 90 degrees in relation to the direction of the acceleration at the loca- tion of the rotator elements (mass).

Claims

Claims1. Arrangement for converting the energy of water waves into a rotational motion, comprising a body (2) arranged to roll in accordance with the motion of the water waves, at least one etongated rotator shaft (3), which is sup- ported on the body (2) to rotate around its longitudinal axis (L), character- ized in that two rotator elements (4, 5) are arranged on the rotator shaft (3), which are located in the longitudinal direction of the rotator shaft (3) at a distance with respect to each other and their centers of gravity being lo- cated on opposite sides of the longitudinal axis (L) in relation to the direction of rotation of the rotator shaft (3), that the rotator shaft (3) is oriented in the direction of its longitudinal axis (L) on average parallel to the vertical plane passing through the direction of the motion of propagation (W) of water waves, while the rotator shaft (3) is swinging back and forth with the body(2) in the vertical plane on average passing through the direction of the mo- tion of propagation (W) of water waves, which swinging of the rotator shaft(3) forces the rotation of the center of gravity of each rotator element (4, 5) around the rotator shaft (3).

2. The arrangement according to claim 1, characterized in that the body (2) is a tank or float formed to float on water waves, the rotator shaft (3) being arranged in a space (S) defined by the body walls.

3. The arrangement according to claim 1 or 2, characterized in that the rotator shaft (3) is arranged in a support (6) arranged in connection with the body (2).

4. The arrangement according to any of the preceding claims 1 to 3, char- acterized in that the rotator shaft (3) is equipped with means for power take-off.

5. The arrangement according to claim 4, characterized in that the means for power take-off comprise a generator arranged on the rotator shaft (3).

6. The arrangement according to any of the preceding claims 1 to 5, char- acterized in that additional tanks (2b, 2b') are arranged on the inside, out- side and / or part of the outer shell of the body (2), which tanks can be filled with water and / or where water can be transferred between the additional tanks.

7. The arrangement according to claim 6, characterized in that the addi- tional tanks (2b, 2b') are placed in the area of the bottom of the body (2) and on the side of the body in such a way that they can be applied to influ- ence the weight distribution within the body (2) so that the tilt angle of body (2) changes.

8. The arrangement according to any of the preceding claims 1 to 7, char- acterized in that the body (2) is anchored in place with the intended an- choring or fastening means (2a).

9. The arrangement according to claim 8, characterized in that the anchor- ing or fastening means (2a) are attached at their upper end to a part of the body 2, which is located on the side of the bearing (6a) or support element supporting the end of the rotator shaft (3).

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