Wave power unit, a use of a such and a method of producing electric energy

Abstract

The invention relates to a wave power unit with a floating body (1), a submerged station (2) and flexible connection means (3) connecting the floating body (1) to the submerged station (100). The submerged station (100) has a stator 5 (5) and a moving part (6). According to the invention the flexible connection means (3) is provided with a damper (12). The damper (12) is arranged to absorb tensile forces in the flexible connection means (3). The invention also relates to a use of such a wave power unit and to a 10 method for producing and supplying electric energy.

Claims

1. A wave power unit which comprises: a floating body arranged for floating on a sea surface, a tensile force-absorbing damper which includes a housing defined by parallel upper and lower end walls and a side wall between the upper and lower end walls, a movable wall inside the housing which is parallel to the upper and lower end walls and is movable towards and away from the upper and lower end walls, and a compressible component positioned between the movable wall and the lower end wall, said housing being an integral part of said floating body, a submerged station which includes a generator having a stator and a movable part, and a flexible connection means which defines a first end that is connected to said movable part of said generator and an opposite second end which is connected to said movable wall of said damper via an attachment device that extends through an opening in the lower end wall of the housing and connects to said movable wall of said damper, said damper absorbing tensile forces in the flexible connection means during use of the wave power unit.

2. The wave power unit according to claim 1, wherein the generator comprises a linear generator and the moving part comprises a linearly reciprocating translator.

3. The wave power unit according to claim 1, including a second damper at flexible connection means forming a security device connecting the at least one floating body to a stationary part of the submerged station.

4. The wave power unit according to claim 3, wherein the second damper is located between the stationary part of the submerged station and the flexible connection means forming a security device.

5. The wave power unit according to claim 1, wherein the compressible component includes a plurality of elastic disc-shaped bodies arranged in a stack and a rigid disc-shaped member between each pair of adjacent elastic disc-shaped bodies.

6. The wave power unit according to claim 5, wherein the number of flexible disc-shaped bodies is in the range of 5-15.

7. A wave power plant, wherein the wave power plant includes a plurality of wave power units according to claim 1.

8. An electrical network, wherein the network includes a wave power unit according to claim 1.

9. A wave power unit which comprises: a floating body arranged for floating on a sea surface, a submerged station which includes a generator having a stator and a translator movable relative to the stator, a tensile force-absorbing damper which includes a housing defined by parallel upper and lower parallel end walls and a side wall between the upper and lower end walls, a movable wall inside the housing which is parallel to the upper and lower end walls and is movable towards and away from the upper and lower end walls, and a compressible component positioned between the movable wall and the upper end wall, said housing being an integral part of said translator, and a flexible connection means which defines a first end that is connected to said movable wall of said damper via an attachment device that extends through an opening in the upper end wall of the housing and connects to said movable wall of said damper and an opposite second end which is connected to said floating body, said damper absorbing tensile forces in the flexible connection means during use of the wave power unit.

10. The wave power unit according to claim 9, wherein the compressible component includes a plurality of elastic disc-shaped bodies arranged in a stack and a rigid disc-shaped member between each pair of adjacent elastic disc-shaped bodies.

11. The wave power unit according to claim 9, wherein the generator comprises a linear generator and the translator comprises a linearly reciprocating translator.

12. The wave power unit according to claim 9, including a second damper at flexible connection means forming a security device connecting the at least one floating body to a stationary part of the submerged station.

13. The wave power unit according to claim 12, wherein the second damper is located between the stationary part of the submerged station and the flexible connection means forming a security device.

14. A wave power unit which comprises: a floating body arranged for floating on a sea surface, a submerged station which includes a base foundation, a tensile force-absorbing damper which includes a housing defined by parallel upper and lower end walls and a side wall between the upper and lower end walls, a movable wall inside the housing which is parallel to the upper and lower end walls and is movable towards and away from the upper and lower end walls, and a compressible component positioned between the movable wall and the upper end wall, said housing being an integral part of the base foundation of the submerged station, and a flexible connection means which defines a first end that is connected to said movable wall of said damper and an opposite second end which is connected to said floating body.

15. The wave power unit according to claim 14, wherein the compressible component includes a plurality of elastic disc-shaped bodies arranged in a stack and a rigid disc-shaped member between each pair of adjacent elastic disc-shaped bodies.

Description

SHORT DESCRIPTION OF THE DRAWINGS

(1) FIG. 1. Is a schematic side view of a wave power unit according to the invention.

(2) FIG. 2 in a similar view schematically illustrates various location of the damper.

(3) FIG. 3 is a longitudinal section through a damper in its released state.

(4) FIG. 4 is a section similar to that of FIG. 3 illustrating the damper in compressed state.

(5) FIG. 5 is an enlarged detail section of FIG. 3.

(6) FIG. 6 is an enlarged detail section of FIG. 4.

(7) FIGS. 7 and 8 in a similar section as in FIG. 3 illustrate two further examples of the damper.

(8) FIGS. 9 and 10 illustrate still further examples of the damper

(9) FIG. 11 schematically illustrates application of the damper in another example of the invention.

(10) FIG. 12 in a schematic view from above illustrates a wave power plant according to the invention.

DESCRIPTION OF EXAMPLES

(11) FIG. 1 is a schematically side view of a wave-power unit according to the invention at operation in the sea. A floating body 1 floats on the sea surface and is connected by a connection means 3 such as a cable, wire, rope, chain or the like, to a linear generator 2 anchored at the sea bed and which forms a part of a submerged station 100. In the figure the generator is attached at the sea bed by means of a base foundation 10. It is, however, to be understood that the generator can be located above the sea bed and be anchored in some other way.

(12) The linear generator 2 has a stator 5 with windings and a translator 6 with magnets. The translator 6 is able to reciprocate up and down within the stator 5 thereby generating current in the stator windings, which current by an electric cable 11 is transferred to an electrical network.

(13) The translator 6 is provided with a rod 7 to which the wire 3 is attached. Alternatively the wire 3 can be attached directly to the translator 6, either at the top thereof or at the bottom or somewhere in between. When the floating body 1 due to the wave movements of the sea surface is forced to move up, the floating body will pull the translator 6 upwards. When the floating body thereafter moves down the translator 6 will move down through gravity. Optionally, but preferably a spring (not shown) or the like acting on the translator 6 provides an additional force downwards.

(14) Since the generator 2 is anchored in the sea bed and the floating body 1 floats freely on the water surface, the floating body is free to move laterally in relation to the generator 2. Thereby the connection means 3 will become inclined.

(15) At the entrance of the connection means 3 into the housing 4 of the generator 2 there is provided a guiding device 9 that guides the connection means to move vertically below the guiding device 9 while allowing the connection means 3 that is above the guiding device to move in an inclined position. The guiding device 9 is attached to a conical construction 8 above the housing 4 of the generator and attached thereto.

(16) The guiding device 9 allows the connection means 3 to gradually change its direction when passing through guiding device 9, such that the wear of the connection means becomes limited.

(17) The wire 3 is provided with a damper 12 arranged to absorb snap loads when the wire 3 suddenly becomes tensioned after having been released. In this example the damper is provided between an upper section 3a and a lower section 3b of the wire 3.

(18) In FIG. 2 alternative positions of the damper are illustrated and marked with crosses. The position 12a corresponds to the example of FIG. 1. In the position 12b the damper is arranged between the wire 3 and the bottom end of the translator 6. In the position 12c the damper is arranged between the wire 3 and the floating body 1.

(19) The wave power unit may be provided with a security device as also illustrated in FIG. 2. The security device is a wire 31 attached at one end to the floating body 1 and at the other end to a stationary part of the submerged station, in this example to the base foundation 10 thereof. The security wire 31 is for the purpose of capturing the floating body 1 from drifting away in case the ordinary wire 3 should be broken. Thus during normal operation the security wire 31 is a passive component. The length of the security wire 31 is larger than the ordinary wire 3 such that the floating body can make limited lateral movements without tensioning the security wire 31. In order to keep control on the security wire, a float 32 is connected to a connection point 33 of the security wire. The excess length of the security wire 31 thereby forms a loop. 34.

(20) As shown, also the security wire 31 can be provided with a damper, either at the connection thereof to the floating body 1, position 12d, somewhere along the security wire 31, position 12e or at the connection thereof to the base foundation, position 12f.

(21) An example of the damper 12 is illustrated more in detail in FIG. 3-6. In FIG. 3 the damper is illustrated in an unloaded state. The damper 12 has a housing consisting of an upper end wall 16, a lower end wall 17 and a circumferential wall 15 extending therebetween. The upper end wall 16 is by a connection device 13 attached to an upper section 3a of the wire 3. The lower end wall 17 has a central opening 18, allowing passage of an attachment device 14 attached to a lower section 3a of the wire 3. The upper end of the attachment device 14 has a wall 20 attached thereto, which wall is able to move vertically within the housing 15, 16, 17.

(22) Between the lower end wall 17 of the housing and the movable wall 20 there is a compressible component 22, which is squeezed between a support surface 19 at the lower wall 17 and a support surface 21 at the movable wall 16. The movable wall 16 is vertically movable in relation to the housing 15, 16, 17 and is in FIG. 3 in its upper end position.

(23) Upon high tension in the wire 3, the movable end wall moves downwards in relation to the housing, whereby the compressible body component is compressed between the support surfaces 19 and 22. In FIG. 4 the damper is illustrated in the maximum compressed stage, at which the movable wall 20 is at a relatively short distance from the lower end wall 17 and the compressible component 22 is squeezed to a relatively small thickness. The spring characteristic of the compressible body is such that it requires a considerably strong tension force to reach the state shown in FIG. 4. Such strong forces occur as snap loads when the translator 6 is at its end positions and alter its direction of movement. The forces occurring during the movement of the translator 6 are of a much lower magnitude and will only marginally compress the compressible component 22.

(24) The compressible component 22 consists of a plurality of disc-shaped elastic bodies 23 of rubber or the like separated by rigid plates 24, e.g. of metal. This can be seen more in detail in FIG. 5 illustrating the uncompressed state and FIG. 6 illustrating the compressed state.

(25) FIG. 7 is an example with an alternative position of the damper, corresponding to position 12b in FIG. 2. Thus the damper 12 is arranged between the wire 3 and the translator 6, in the illustrated example at the lower end of the translator 6. The housing 15, 16, 17 of the damper 12 forms an integrated part of the translator 6. The wire 3 is attached to the movable wall 16, which in this fig. Is illustrated at the position when the damper is unloaded. The damper 12 is of the same kind as disclosed in FIG. 3-6, but is mounted upside down in relation to the example in those figures.

(26) The translator has a centrally arranged axial hole 26 therethrough, through which the wire 3, or alternatively a rod 7 such as in FIG. 1, reaches the bottom of the translator 6. The figure also shows the magnets 25 of the translator 6.

(27) FIG. 8 illustrates a further alternative position of damper corresponding to position 12c in FIG. 2. In this case the housing 15, 16, 17 of the damper forms an integral part of the floating body 1, and the movable wall 20 is attached to the upper end of the wire 3.

(28) An alternative example of the damper 121 is illustrated in FIG. 9. The damper 121 in this example differs from the one of FIG. 3 only in that the compression component 22 consists of one single elastic member, e.g. of rubber.

(29) A further alternative is depicted in FIG. 10, where the damper consists of a spiral tension spring 122. Whereas in the earlier examples the damper is compressed when high forces occur, the spring 122 will expand upon occurrence of tensile forces.

(30) The invention can also be applied to a wave power unit of the kind where the generator is a traditional generator, with a rotating rotor 61 and a surrounding stator 51 as shown in FIG. 11. A cylindrical body 62 is connected to the rotor 61 and rotates therewith. As the floating body moves up and down the wire is unwounded and wounded, respectively on the cylindrical body 62 for rotating the rotor 61. The damper 12 in this example performs the same function as the damper of the linear generator described above.

(31) FIG. 12 in a schematic view from above illustrates a wave power plant with a plurality of generators 2 of wave power units according to the invention. The generators 2 are connected to a submerged switchgear 30, which via a connection line 41 is connected to an electrical network 40, such as a grid. A control device controls the energy supply and measures the amount of electric energy supplied, e.g. for billing.