WO2005071258A1

WO2005071258A1 - Arrangement for utilizing wave power

Info

Publication number: WO2005071258A1
Application number: PCT/FI2005/000050
Authority: WO
Inventors: Esko Raikamo
Original assignee: Esko Raikamo
Priority date: 2004-01-27
Filing date: 2005-01-26
Publication date: 2005-08-04
Also published as: FI20040111A0; FI20040111A

Abstract

An arrangement for utilizing wave power. The arrangement (1) comprises means (4, 4a, 4b, 29a, 29b) for converting the kinetic energy of water into a reciprocating rotary motion. The arrangement (1) comprises a conversion unit (8, 8a, 8b) of rotary motion that is arranged to convert the reciprocating rotary motion into a substantially continuous and unidirectional rotary motion, and a power take-off (18) for transferring the unidirectional and substantially continuous rotary motion. The arrangement (1) is arranged to be substantially entirely below the surface of water.

Description

ARRANGEMENT FOR UTILIZING WAVE POWER [0001] The invention relates to an arrangement for utilizing wave power, the arrangement comprising means for converting the kinetic energy of water into a reciprocating rotary motion. [0002] It has been estimated that by using the wave power of the seas in the world, it would be possible to satisfy the current energy demand of the entire human kind multifold. Wave power is, however, still a mainly unutilized energy source. For the purpose of recovering and utilizing wave power, numerous different wave power plant solutions have been presented to provide electric energy from the movement of the waves. Some such wave power plants are based on items or structures floating on the surface of water and moving or oscillating by the force of the waves. The movement is usually transmitted to a hydraulic pump and the pressure fluid pressure provided by the pump is arranged to rotate an electric generator. Wave power plant solutions are also known in which the structures moved by the waves are sunk substantially entirely below the surface of water. In these wave power plants, too, wave energy is converted to conventional hydraulic pressure prior to transforming it into electric energy. [0003] The above-mentioned wave power plants have some problems that are mainly caused by the multiphase transformation of wave energy into electric energy. In particular, a rather low efficiency and a complex and thus expensive and fault-sensitive structure of the plants should be mentioned herein. [0004] It is an object of the present invention to provide a novel and improved arrangement for utilizing wave power, which avoids the drawbacks mentioned above. [0005] The arrangement of the invention for utilizing wave power is characterized in that the arrangement comprises a conversion unit of rotary motion, which is arranged to convert the reciprocating rotary motion caused by the movement of waves into a substantially continuous and unidirectional rotary motion, and a power take-off for transferring the unidirectional and substantially continuous rotary motion, and that said means and conversion unit are arranged to be substantially entirely below the surface of water. [0006] The essential idea of the invention is that the energy generated by the surge of water is recovered under water as a reciprocating rotary motion that is immediately converted into a mechanical unidirectional rotary motion that in turn is transmitted to rotate an electric generator, a pump, or a corresponding power unit. [0007] The invention provides the advantage that wave energy is converted in a simple and energy-efficient way into a continuous unidirectional rotary motion. The system of the invention is applicable in a versatile manner to different operating conditions: the means used to transform the kinetic energy of water into a reciprocating rotary motion can for instance be pendulum plates that are fastened tumably to their base and turn back and forth relative to their base by the motion of water, or propellers, or turbines, or the like. The system is not only applicable to produce electricity to an electric network, but also to navigation marks, sea route lights, buoys, beacons, or other corresponding electrically driven units, either alone or together with solar cells or wind power. Further, the system can be applied to the electrification of islands to which it is not economical to build an electric line. [0008] A further advantage is that the reciprocating rotary motion generated by the above-mentioned means can be utilized efficiently and even in the case that the force or frequency of water movement change irregularly. Because the arrangement is arranged entirely under water, the freezing of the water system will not cause problems. [0009] Yet another advantage is that, with the arrangement, it is possible to utilize underwater water motion whose energy is considerably greater than the wave motion on the surface. [0010] The idea of a preferred embodiment of the invention is that a generator, preferably a permanent magnet generator, is connected directly without a gear system to the conversion unit of rotary motion. The advantage is that the transformation of wave energy into electric energy is very efficient. [0011] The idea of a second preferred embodiment of the invention is that the arrangement is arranged to a wind power plant. The advantage is that, this way, the wave power plant and wind power plant can utilize common hardware and systems with which electric energy can be produced and forwarded on. At the same time, the energy production of the wind power plant can be ensured and more energy generated even though the wind was too weak to turn the rotor of the wind power plant, or the rotor was made stationary due to too high winds. [0012] The invention is described in more detail in the attached drawings, in which Figure 1 is a schematic partly sectional side view of an arrangement of the invention, Figure 2 is a schematic front view of the arrangement of Figure 1 , Figure 3 is a schematic view of a rotary motion conversion unit of the arrangement of the invention in partial cross-section level with its power take-off shaft, Figure 4 is a schematic partly sectional top view of a second arrangement of the invention, Figure 5 is a schematic view of a second rotary motion conversion unit of the arrangement of the invention, Figure 6 is a schematic side view of a third arrangement of the invention, and Figures 7a to 7c are schematic views of a third rotary motion conversion unit of the arrangement of the invention. [0013] Figure 1 is a schematic partly sectional side view of an arrangement of the invention for utilizing wave power, and Figure 2 is a schematic front view of the arrangement of Figure 1. [0014] The components of the arrangement 1 are mainly arranged on the top surface of a submarine base 3 of a wind power plant 2. Said base 3 may either be fixed to the sea bed or it may be movable from one site to another depending on the need. It should be noted that the arrangement 1 can naturally be implemented without the wind power plant 2, for example by fastening it directly to the sea bed or to a fixed or movable artificial support structure arranged below the surface of the sea. [0015] The arrangement 1 comprises several pendulum plates 4 that are at their bottom edge fastened stationary to a lay-shaft 5. The lay-shaft 5 is in turn fastened rotatably to fastening elements 6 that are fastened stationary to the base 3 of the wind power plant. The lay-shaft 5 and the pendulum plate 4 fastened thereto can swing or turn back and forth relative to the fastening elements 6 and the base 3 of the wind power plant with the lay-shaft 5 acting as the centre point of the movement. In Figure 1 , the turning movement is indicated by arrow M. [0016] The movement generated by the surge of water W causes pressure differences on different sides of the pendulum plate 4, which push the pendulum plate 4 off balance. An air space 7 is arranged in the top section of the pendulum plate 4. The buoyancy caused by the air space 7 endeavours to turn the pendulum plate 4 tilted by the water movement back to the vertical balance position, in which it is shown in Figure 1. The air space 7 is, however, not essential for the implementation of the invention. [0017] As the pendulum plate 4 turns as shown by arrow M, the lay- shaft 5 also turns with it. The lay-shaft 5 is connected to a conversion unit 8 of rotary motion, which is fastened to the base 3 of the wind power plant. The structure of the conversion unit is described in more detail below. [0018] The lay-shaft 5 turns the power take-off shaft of the conversion unit. The reciprocating rotary movement of the power take-off shaft is converted in the conversion unit 8 into a unidirectional rotary motion of the output shaft of the unit. The unidirectional rotary motion is transmitted from the power take-off of the conversion unit to a drive shaft of an electric generator 9 connected directly thereto. The power take-off and the drive shaft of the electric generator 9 are connected to each other to rotate at the same rotation rate. The electric generator 9 is preferably a permanent magnet generator that generates usable electric energy even at low rotation rates. The electric energy generated by the electric generator 9 is transmitted by means of an electric cable 10 to the electric system of the wind power plant 2 and onwards for utilization. [0019] The unidirectional rotary motion provided by the conversion unit 8 can naturally also be transmitted through a suitable gear system or power transmission system to the electric generator. [0020] The arrangement shown in Figures 1 and 2 comprises several pendulum plates 4, each with a conversion unit 8 and electric generator 9 connected thereto. The arrangement of the invention can also be implemented to comprise only one pendulum plate 4 with a conversion unit 8 and electric generator 9 connected thereto. [0021] Two or more pendulum plates 4 can also be connected together and to the same conversion unit 8 and electric generator 9. [0022] Instead of the electric generator 9, the conversion unit 8 can also be connected to drive a hydraulic pump that converts the rotational energy into pressure fluid energy, a pneumatic pump that converts the rotational energy into pressurized gas energy, or a corresponding power unit. [0023] The pendulum plates 4 of the system 1 are arranged below the surface of water such that their top edge is at depth D from the water surface. If the system is at a latitude, where the water surface may freeze, depth D is preferably so deep that the pendulum plate 4 still remains in free water. Ice formation or movement then do not damage the system 1. [0024] Figure 3 is a schematic view of a rotary motion conversion unit of the arrangement of the invention in partial cross-section level with its power take-off shaft. The conversion unit 8 can for instance be used in the arrangement shown in Figures 1 and 2 to utilize wave power. [0025] The power take-off shaft 15 of the conversion unit 8 rotates back and forth into a first direction A and a second direction B. The power take-off shaft 15 is at one end mounted by a bearing 16 to a mantle 17 that is fastened coaxially to the power take-off 18 shaft 19. At its opposite end, the power take-off shaft 15 is connected to the lay-shaft 5 providing reciprocating movement, which is not shown in Figure 3 to simplify the presentation. A first gearwheel 22a belonging to reversing means 21 and a second freewheel clutch 25 are fastened with fastening elements 20 to the power take-off shaft 15. A sleeve 24 is arranged on a power take-off shaft 26 to rotate freely relative to it, and a third gearwheel 22c of the reversing means 21 and a first freewheel clutch 23 are fastened to the sleeve. The locking direction of the freewheel clutches 23 and 25 is shown by arrow L in the figure. A second gearwheel 22b of the reversing means 21 is arranged on the shaft 26 at substantially right angle with the first and third gearwheel 22a, 22c. The outer rims of the freewheel clutches 23 and 25 are fixed to the mantle 17. The power takeoff 18 and reversing means 21 are preferably arranged inside a watertight protective cover 28. [0026] When the power take-off shaft 15 turns into the first direction A, the rotary motion is transmitted in the reversing means 21 as a reverse motion to the first freewheel clutch 23 in its locking direction L, so the rotary motion is transmitted through it to the mantle 17 and the shaft 19 acting as power take-off 18 in the turning direction shown by arrow A. The reciprocating rotary motion of the power take-off shaft 15 is thus received at the power take-off as a unidirectional rotary motion shown by arrow A. [0027] When the power take-off shaft 15 turns into the second direction B - i.e. when for instance the swing direction of the pendulum plate 4 or the rotation direction of a propeller changes - the rotary motion is transmitted through the second freewheel clutch 25 to the mantle 17 and on to power takeoff 18 in the rotating direction shown by arrow A. The first gearwheel 22a of the reversing means 21 fastened to the power take-off shaft 15 also naturally turns with the shaft 15 into the second direction B. In the reversing means 21 , the direction of the rotary motion reverses so that the third gearwheel 22c, the sleeve 24 fastened to it, and the first freewheel clutch 23 turn into the first direction A. This movement does not, however, proceed from the first freewheel clutch 23, because the movement is in its free direction. [0028] Thus, the power take-off shaft 19 always turns in direction A, whether the power take-off shaft turns in direction A or B. Therefore, the rotor of the electric generator 9 also always turns in the same direction. The turning direction or rate of the power take-off shaft 19 is independent of the frequency of the turning direction change of the power take-off shaft 15 or of the size of its rotation angle in one direction. [0029] An actuator utilizing the rotary motion can be connected to the power take-off 18; the actuator can be a mill for grinding grain, wood, or the like, or a sawing machine, such as a portable sawmill. [0030] Figure 4 is a schematic partly sectional top view of a second arrangement of the invention. [0031] The arrangement 1 comprises two pendulum plates, namely a first pendulum plate 4a and a second pendulum plate 4b, the structure of which resembles the pendulum plates 4 shown in the previous figures. [0032] A first lay-shaft 5a is connected to the first pendulum plate 4a and, correspondingly, a second lay-shaft 5b is connected to the second pendulum plate 4b to turn with the corresponding pendulum plates. The lay-shafts 5a, 5b thus turn back and forth in accordance with the movement of the corresponding pendulum plate 4a, 4b. [0033] Further, the first lay-shaft 5a is connected to the first conversion unit 8a of rotary motion, to its power take-off shaft 15, to be more precise, and correspondingly, the second lay-shaft 5b is connected to the power takeoff shaft 15 of the second conversion unit 8b of rotary motion. It should be noted that the structure of the conversion units 8a, 8b is shown in more detail in Figure 5. [0034] The conversion units 8a, 8b of rotary motion have a common power take-off shaft 19 that always rotates in one and the same direction. [0035] Figure 5 is a schematic view of rotary motion conversion units of the arrangement of Figure 4 in partial cross-section. Herein, two reciprocating power take-off shafts, a first power take-off shaft 15a and a second power take-off shaft 15b, are connected to turn the shaft 19 acting as power take-off. [0036] The first power take-off shaft 15a is connected to a first lay- shaft 5a and through it to a first pendulum plate 4a. Correspondingly, the second power take-off shaft 15b is connected to a second lay-shaft 5b and through it to a second pendulum plate 4b. [0037] The rotary motion of the power take-off shafts 15a, 15b is transmitted to a second gearwheel of reversion means 21 and on to a first gearwheel 22a and a third gearwheel 22c. The first and second gearwheel 22a, 22c are connected in a corresponding order through first and second freewheel clutches 23, 25 to power take-off 18. The locking direction of the freewheel clutches 23, 25 is shown by arrow L in the figure. The rotary motion of the power take-off shaft 15 is transmitted depending on its direction through either the first or second freewheel clutch 23, 25 to the shaft 19 in the rotating direction shown by arrow A. In the figure, a support pinion 22d is arranged by way of example to the reversing means 21 connected to the rightmost power take-off shaft 15b, the pinion being fitted with a bearing 16 to the shaft 14. The support pinion 22d supports the reversing means 21 at high loads in particular. [0038] An advantage of the embodiment of Figure 5 is that two or more means used to convert kinetic energy into a reciprocating rotary motion can be connected to turn the same power take-off 18. The clearance of the pinions 22a, 22b, 22c of the reversing means 21 is very easy to adjust by setting the distance of the second pinion 22b as needed by moving the power take-off shaft in the direction of the power take-off shaft 15a, 15b. [0039] Figure 6 is a schematic side view of a third arrangement of the invention. Herein, the kinetic energy of water is converted into a rotary motion with a first and a second propeller unit 29a, 29b. The propeller units 29a, 29b are supported and fitted with bearings on frame elements 30a, 30b and further to the bottom. The propeller shafts rotated by the propeller units 29a, 29b are connected to the power take-off shafts 15a, 15b of the rotary motion converter 8, see Figures 7a to 7c. [0040] The rotating direction of the propeller units 29a, 29b may change as water flows change. In whichever direction the propeller units 29a, 29b turn, or even when they turn in opposite directions, the rotary motion converter 8 always produces a rotary motion in one specific direction. An electric generator 9 generating electric energy from rotary motion is directly connected without a transmission ratio to the rotary motion converter 8. When necessary, the frame elements 30a, 30b can also comprise a reducing/increasing gear with which the rotating rate of the propeller unit 29a, 29b is changed to a suitable rotating rate range. [0041] The propeller units are suitable for use especially in circumstances in which the movement of water W is in one and the same direction for a relatively long time and then reverses, such as in tidal areas. [0042] The propeller units can be arranged inside a turbine pipe 33, which is drawn with dashed lines in Figure 6. [0043] In Figure 6, the rotating shaft of the propeller units is arranged to be substantially horizontal. The rotating shaft of the propeller units can also be arranged in some other direction, such as in a substantially vertical direction. In this solution, the propeller unit blades rotating on one side of the plane going through the rotating shaft are arranged behind a suitable flow stop, such as a flow plate, away from the flowing water, and the propeller unit blades rotating on the other side of the plane are in the flowing water. This way, the propeller unit can rotate by the energy from the flowing water. [0044] Figures 7a to 7c are schematic views of the rotary motion conversion unit of the arrangement shown in Figure 6. [0045] Two propeller shafts 31a, 31 b are connected to the conversion unit 8 and can rotate in both directions A and B. The movement of the propeller shafts 31a, 31 b is transmitted to two power take-off shafts 15a, 15b, each connected to one propeller shaft. The propeller shafts 31a, 31 b generate in the power take-off shafts 15a, 15b a rotary motion in the direction of the circumference of the shaft, which direction is shown with arrows A, B in Figures 7a to 7c. [0046] There may be a phase difference between the propeller shafts 31a, 31 b and thus also between the power take-off shafts 15a, 15b so that the direction A, B of their back-and-forth movement changes at different times with respect to each other. In Figure 7a, both power take-off shafts 15a, 15b are turning in the first direction A. First locking elements 23a, 23b and second locking elements 25a, 25b, such as freewheel clutches, are arranged to both power take-off shafts 15a, 15b. [0047] The freewheel clutches have an outer rim and an inner rim and locking elements between them. The rims may rotate freely with respect to each other in one direction, but their rotation into the opposite direction is prevented with the locking elements. The locking direction of the freewheel clutches is shown by arrow L in the figure. Freewheel clutches are known per se and are, therefore, not described in more detail herein. The locking elements can be freewheel clutches or brakes or other stopping units that can be suitably locked and opened in an appropriate manner, for instance electrically, for the operation of the power transmission unit. [0048] In the figure, the locking direction of the first freewheel clutches 23a, 23b is such that when the power take-off shaft 15a, 15b turns in the first direction A, the first freewheel clutches 23a, 23b are locked and the rotary motion is transmitted to the reversing elements 21a, 21 b; the locking direction of the second freewheel clutches 25a, 25b is, however, opposite to that of the first freewheel clutches 23a, 23b, and the rotating direction of the shaft 15a, 15b is in their free direction, and the force of the shaft 15a, 15b is, therefore, not transmitted onwards through the second freewheel clutches 25a, 25b. In the embodiment of the invention, the reversing elements 21a, 21 b comprise three bevel gears 22a, 22b, 22c, of which the adjacent ones are in contact and substantially at a 90° angle to each other so that the first bevel gear 22a and the third bevel gear 22c are arranged coaxially with the power take-off shaft 15a, 15b. The second bevel gear 22b is fitted with bearings to the frame of the unit, which is not shown in the figure for the sake of clarity. The power take-off shaft 15a, 15b is arranged to run through the first and third bevel gears 22a, 22c and the reversing elements 21 a, 21b so that the power take-off shaft 15a, 15b rotates freely with respect to the bevel gears 22a, 22b, 22c and the reversing elements 21a, 21 b. The rotary motion is transmitted from the power take-off shaft 15a, 15b through the first freewheel clutch 23a, 23b to the first bevel gear 22a, second bevel gear 22b and on to the third bevel gear 22c of the reversing element 21a, 21 b, and the rotating direction of the third bevel gear 22c is opposite to that of the power take-off shaft 15a, 15b. [0049] The outer rim of the second freewheel clutch 25a, 25b is arranged to the third bevel gear 22c, and a gearwheel 32 is also arranged to the outer rim for power take-off. The rotating direction of the gearwheel 32 is shown with an arrow in the figure. The rotating direction of the gearwheel 32 is thus opposite to that of the power take-off shaft 15a, 15b, that is, to the first direction A. It is naturally possible to use some other elements than the gearwheel 32 for power take-off, such as belt pulleys, chain pulleys, angle transmission, or some other suitable element with which it is simple and easy to transmit power onwards. [0050] The rotating direction of the first power take-off shaft 15a in Figure 7b is still the first direction A, and it is not explained in any more detail herein, but the rotating direction of the second power take-off shaft 15b has reversed, that is, into the second direction B. Because the second power takeoff shaft 15b now rotates into the free direction of the first freewheel clutch 23b, the rotary motion is not transmitted to the second reversing element 21 b. Instead, the rotary motion of the second power take-off shaft 15b is in the locking direction of the second freewheel clutch 25b arranged on the shaft, and through the second freewheel clutch 25b, the rotary motion is transmitted to the gearwheel 32. Thus, the second power take-off shaft 15b and the gearwheel 32 have the same rotating direction. The rotary motion of the second power take-off shaft 15b is not only transmitted through the second freewheel clutch 25b to the gearwheel 32, but also to the reversing element 21 b that rotates in the same direction all the time whatever the rotating direction of the power take-off shaft 15b is. The rotary motion of the reversing element 21 b is not, however, transmitted through the first freewheel clutch 23b to the shaft 15b, because this rotary motion is in the free direction of the first freewheel clutch 23b. [0051] Figure 7c also shows the rotating direction of the first power take-off shaft 15a into the second direction B. The rotary motion of both power take-off shafts 15a, 15b is now transmitted to the gearwheel 32 in the manner shown in Figure 7b. Regardless of the rotating direction of the propeller shafts 31a, 31 b, the rotary motion of the gearwheel 32 is all the time and continuously in the same direction. [0052] The conversion unit 8 naturally also functions correctly when only one propeller shaft is connected to it, whereby the second power take-off shaft 15 and the machine elements related to it can naturally be left out of the structure. [0053] The drawings and the related description are only intended to illustrate the idea of the invention. The invention may vary in detail within the scope of the claims. Thus, in some embodiments, more than one power unit can be connected to the power take-off shaft of the conversion unit for rotary motion by means of gearwheels or corresponding transmission elements, for instance.

Claims

CLAIMS 1. An arrangement for utilizing wave power, the arrangement comprising means (4, 4a, 4b, 29a, 29b) for converting the kinetic energy of water into a reciprocating rotary motion, the arrangement comprising a conversion unit (8, 8a, 8b) of rotary motion that is arranged to convert the reciprocating rotary motion caused by water movement into a substantially continuous and unidirectional rotary motion, and a power take-off (18) for transferring the unidirectional and substantially continuous rotary motion, and the means (4, 4a, 4b, 29a, 29b) and the conversion unit (8, 8a, 8b) are arranged substantially entirely below the surface of water, characterized in that the arrangement is arranged to a wind power plant (2).

2. An arrangement as claimed in claim 1, characterized in that the rotary motion conversion unit (8, 8a, 8b) comprises a power take-off shaft (15, 15a, 15b) turning back and forth around its longitudinal axis, reversing means (21, 21a, 21b) arranged between the power takeoff shaft (15, 15a, 15b) and the power take-off (18), a first locking element (23, 23a, 23b) and a second locking element (25, 25a, 25b), by means of which reversing means (21, 21a, 21b) and locking elements (23, 23a, 23b, 25, 25a, 25b) the reciprocating rotary motion of the power take-off shaft (15, 15a, 15b) is converted into a unidirectional rotary motion of power take-off (18), that the reversing means (21, 21a, 21b) and locking elements (23, 23a, 23b, 25, 25a, 25b) are arranged so that when the power take-off shaft (15, 15a, 15b) rotates in a first direction (A), the rotary motion is transmitted through the first locking element (23, 23a, 23b) to power take-off (18), and that when the power take-off shaft (15, 15a, 15b) rotates in a second direction (B), the rotary motion is transmitted through the second locking element (25, 25a, 25b) to power take-off (18).

3. An arrangement as claimed in claim 2, characterized in that the locking elements (23, 23a, 23b, 25, 25a, 25b) are freewheel clutches.

4. An arrangement as claimed in claim 2, characterized in that the locking elements (23, 23a, 23b, 25, 25a, 25b) are brake units.

5. An arrangement as claimed in any one of claims 2 to 4, c h a r - acterized in that the reversing means (21, 21a, 21b) comprise gearwheels (22a, 22b, 22c) in contact with each other.

6. An arrangement as claimed in any one of the preceding claims, characterized in that the means for converting the kinetic energy of water into a reciprocating rotary motion is a pendulum plate (4, 4a, 4b).

7. An arrangement as claimed in any one of claims 1 to 5, c h a r - acterized in that the means for converting the kinetic energy of water into a reciprocating rotary motion is a propeller unit (29a, 29b).

8. An arrangement as claimed in any one of the preceding claims, characterized in that an electric generator (9) is connected to power take-off (18).

9. An arrangement as claimed in claim 8, characterized in that the electric generator (9) is a permanent magnet generator.

10. An arrangement as claimed in claim 8 or 9, characterized in that power take-off (18) and the drive shaft of the electric generator (9) are directly coupled so that they rotate at the same rotating rate.

11. An arrangement as claimed in any one of the preceding claims, characterized in that at least two means (4, 4a, 4b, 29a, 29b) are connected to the rotary motion conversion unit (8, 8a, 8b) to convert the kinetic energy of water into a reciprocating rotary motion.