WO2004005710A1

WO2004005710A1 - Device and method for generating lifting force

Info

Publication number: WO2004005710A1
Application number: PCT/SE2003/001155
Authority: WO
Inventors: Lars ÖSTHOLM
Original assignee: Oestholm Lars
Priority date: 2002-07-09
Filing date: 2003-07-03
Publication date: 2004-01-15
Also published as: SE524227C2; AU2003244288A1; SE0202154L; SE0202154D0

Abstract

The invention relates to a device for generating a lifting force for extraction of energy from a medium flowing by, comprising an elongated body (11) having an outer surface (12) for affecting a first medium flowing by, a first end (13) connected to an underlayer through a bearing (19) and a free second end (14), wherein the elongated body (11) is arranged pivotally around at least one portion of the bearing (19). The elongated body (11) comprises a plurality of slits (25) for a second medium flowing out through the slits (25), wherein the second medium flows out towards the outer surface (12) to affect the first medium flowing by the outer surface (12) while generating a lifting force. Further, the slits (25) are adjustable, wherein a direction of the second medium flowing out is adjustable for alternating a direction of the lifting force while bringing the elongated body (11) around the bearing (19).

Description

Device and method for generating lifting force.

FIELD OF THE INVENTION The present invention relates to a device and a method for generating a lifting force for extraction of energy from a medium flowing by the device. Particularly the present invention relates to a wind power plant or a water power plant and a method for such power plant for generation of lifting force for extraction or conversion of energy from an air flow or a water flow flowing by the device. This type of devices is commonly used for transformation of wind power or water power to electric energy and can be used by industry, such as electric power companies and other producers of electric power, as well as users, such as domestic establishments and other consumers.

PRIOR ART

A plurality of devices for extraction of energy from a bypassing air flow or water flow, such as different types of wind power plants and water power plants, are described in the prior art. One common type of wind power plants comprises a wind turbine arranged in a top portion of a tower. The wind turbine comprises a horizontally arranged shaft and a plurality of turbine blades, or rotor blades, arranged around the shaft, which turbine blades are brought to rotate around the horizontal shaft by means of an air flow flowing by the wind power plant, wherein wind energy is transformed into electric power by means of a generator. Common wind power plants of this type further comprise a toothed transmission gear to increase the rotation speed so that this fits standard type generators. To direct the wind turbine towards the wind an electric or hydraulic yaw machinery is commonly used. For example, the running operation is handled automatically by means of computers, which start the wind power plant when the wind is sufficient and stop it if a storm or error should occur. To stop the wind turbine a combination of mechanical and aerodynamic braking is often used.

Another type of devices for conversion of wind power to electric power of prior art is the so called Darrieus turbine. It comprises one or more elon- gated and arched rotor blades connected in both ends to a vertical shaft, such as a vertically arranged tower or similar. The rotor blades are arranged so that they can rotate around the vertical shaft, wherein wind energy can be transformed into electric energy by means of a generator. Usually this type of wind power plant comprises two or three rotor blades, which are flexible and carried in a bearing in an axial direction to the vertical shaft. Due to centrifugal force the ends of the rotor blades are compressed along the vertical shaft when operated, wherein the swept area varies depending on the rate of rotation. One problem with this type of wind power plants is that they are costly and require large plants to keep the costs for electric power production low. Consequently, wind power plants of prior art can hardly be used for the production of domestic electricity, for example directly at the location of the user or consumer. Further one problem with prior art wind power plants is that they can cause negative environmental effects due to that they are visible from a large distance and, consequently, result in a disturbing element in the landscape. This type of wind power plants further cause environmental effects in the form of noise. It is not unusual that prior art wind power plants are heard from a distance of several hundred meters.

One drawback with such prior art wind power plants is that they are provided with a complicated structure having a plurality of moving parts, which leads to low reliability in operation and less cost-effective mounting and maintenance. Further one drawback with wind power plants comprising a Darrieus turbine is the low efficiency.

BRIEF DESCRIPTION OF THE INVENTION One object of the present invention is to negate above mentioned disadvantages and problems of prior art devices for extraction of energy, such as wind power plants. The invention provides a cost effective device and method, which is suitable for domestic use as well as for large scale producers of electric power. Further a more reliable and environment friendly device is provided, not disturbing the landscape due to that a less conspicuous elongated body of pendulum-type is used instead of rotor blades. One draw- back with prior art devices is that the rotating movement draws attention to the device, which can result in a negative environmental influence. One additional object of the present invention is to provide a device and a method for generating a lifting force for extraction of energy. Further one object of the present invention is to provide a device and method for generating a lifting force for extraction of energy from a gaseous medium flowing by, such as air. Further one object of the present invention is to provide a device and method for generating a lifting force for extraction of energy from a liquid medium flowing by, such as water. Yet another object of the present invention is to provide an effective alternation of the direction of the lifting force. Further one object of the present invention is to utilize the elongated body for extraction of energy. According to prior art devices a tower is used to raise the wind turbine or rotor blades above ground level, wherein only a small portion of the structure of known wind power plants is used for extraction of energy. This is obtained by the invention provided with the features of claim 1 and 7. The device according to the invention comprises an elongated body having an outer surface for affecting a first medium flowing by, a first end connected to an underlayer through a bearing and a second end projecting from the first end, wherein the elongated body is arranged pivotally around at least one portion of the bearing. The device may be arranged as a pendulum wind power plant, wherein the first medium flowing by is air flowing by. Alternatively, the device is arranged as a water power plant, wherein the first medium flowing by is water. The device may comprise conventional transmission, such as hydraulic cylinders or similar, for transformation of kinetic energy to, for example, electric energy. Hence, the first medium flows against the elongated body and is forced around its circumference.

The device comprises an elongated body connected to a counterweight and a bearing, wherein the elongated body can swing around the bearing. The elongated body comprises a first end connected to an under- layer through the bearing and a free second end. The device can further comprise supports connected to the bearing and a turning foundation so that the device can be turned according to the direction of the medium flowing by. For example, the device comprises a conventional yaw machinery so that the device can be turned according to the direction of the medium flowing by. For example, the foundation is connected to underlying ground.

The elongated body comprises a plurality of slits for a second medium flowing out through the slits. The slits are arranged so that the second medium flows out towards the outer surface to affect the first medium flowing by while generating a lifting force. For example, the second medium flows through the elongated body and out through the slits. For example, the second medium flows in a space inside the elongated body. Hence, the elongated body may be hollow or may comprise a passage for the second medium. Alternatively, the elongated body may comprise, or may be connected to, one or more passages or tubings for conducting the second medium flowing out to the slits.

The elongated body may further comprise, or may be connected to, a device for improving the flow of the second medium to the slits. For example, a fan or similar may be arranged in one portion of the elongated body to pro- vide or improve the flow of the second medium. Alternatively, a pump or similar may be arranged in the elongated body to provide or improve the flow of the second medium. Alternatively, the device for improving the flow of the second medium to the slits can comprise a space, a passage, a tubing or similar for conducting the second medium inside the elongated body and/or to the slits. For example, the elongated body can comprise one or more inlets for the second medium so that the second medium can be brought to the slits through passages or similar.

Also the second medium can be a gaseous or liquid medium, such as air or water or similar. For example, the second medium is the same medium as the first medium, wherein the second medium flowing out is brought from the same source as the first medium flowing by. Hence, one portion of the medium flowing by can be brought into an inlet in the elongated body and be conducted to the slits through passages or similar, wherein the second medium flowing out is provided.

The slits are suitably distributed around the elongated body and may extend in the longitudinal direction of the elongated body. Alternatively, the slits are formed as a plurality of aligned apertures. For example, the slits are arranged as a perforation or a plurality of perforations. The slits may be arranged in an inclined angle towards the elongated body so that the second medium flows out substantially tangentially around the circumference of the elongated body. Hence, a lifting force is generated by that the first medium flowing by is affected and follows the second medium flowing out. The device can be arranged so that the lifting force is generated substantially perpendicular to the direction of the first medium flowing by.

The slits are adjustable so that a direction of the second medium flowing out is adjustable, wherein a direction of the lifting force can be alternated. Hence, a lifting force is generated in a direction perpendicularly to the direction of the medium flowing by so that the elongated body is brought in the direction of the lifting force. Then, the direction of the second medium flowing out is alternated so that the direction of the lifting force is alternated while bringing the elongated body around the bearing. Thus, an effective pendulum movement of the elongated body is provided so that energy can be extracted.

An effective direction of the slits can be fixed or adjustable. Slits having a fixed effective direction can be activated and closed depending on desired direction of the lifting force. For example, the device comprises one set of slits arranged in an inclined angle towards a circumference of the elongated body so that the second medium flowing out is brought to flow in a clockwise direction along the outer surface of the elongated body and at least one set of slits arranged in an inclined angle towards a circumference of the elongated body so that the second medium flowing out is brought to flow in a counter-clockwise direction along the outer surface of the elongated body. For example, the clockwise slits are activated when a lifting force in one direction is desired, wherein the counter-clockwise slits are closed. When lifting force in the opposite direction is desired, the counter-clockwise slits are acti- vated, wherein the clockwise slits are closed. The activation and the closing of the slits can be accomplished by connecting them to and separating them from, respectively, the second medium flowing inside the elongated body. For example, dampers can be arranged along at least one portion of each slit. Hence, a single leaf damper or slide damper or similar can be arranged just inside the slit and along its entire length. For example, the slits can be made openable, wherein they function both as slit and damper. Hence, a rapid alternation of the lifting force is obtained. Alternatively, the dampers and the slits can be arranged forming a distribution space, such as a passage, wherein a damper can serve one or more slits and the positioning of the dampers is more independent. Slits having adjustable effective direction can be activated at all times. Instead the direction of the slits can be alternated by means of a mechanism suitable for the purpose.

The alternation of the slits can be designed in a plurality of manners. For example, the device can comprise one pivotal means or a plurality of pivotal means, opening and closing the slits. The pivotal means can be formed as a damper allowing opening and closing of the slits. The dampers can be arranged in the form of a single leaf damper or a slide damper. Alternatively, the pivotal means can be arranged in the form of a pivoted wall element hav- ing a hinge means arranged in a centre portion thereof, wherein the slits can be opened and closed by turning the wall element. For example, the passage inside the elongated body can be divided by dividing walls so that the second medium can be brought to a set of slits or individual slits to control the direction of the second medium flowing out. Alternatively, the slits can be provided by means of hinged plates or plate elements, wherein slits can be opened and closed. The elongated body can comprise two sets of slits, one of which sets is directed so that the second medium flowing out flows in a clockwise direction and the other set is directed so that the second medium flows in a counter-clockwise direction around the elongated body. By bringing the sec- ond medium to flow out through one set of slits at a time the pendulum movement is obtained. Alternatively, all of the slits can be pivotally arranged, wherein all of the slits are directed in a clockwise direction to generate lifting force in one direction and counter-clockwise to generate lifting force in the opposite direction, respectively. However, it is obvious to a person skilled in the art that the slits can be formed in a plurality of ways within the scope of the present invention.

The elongated body can be arranged symmetric to provide a uniform distribution of the lifting force. Hence, the device has no typical angle of incidence, which is the case in conventional wind power plants. For example, the elongated body is formed as a cylinder, wherein a larger lifting force per unit of surface is obtained compared to conventional wing profiles. For example, the elongated body is formed as a circular cylinder. The elongated body fur- ther results in a lifting force within a large range of angles of incidence and the direction of the lifting force can be altered by alternating the slits.

The method according to the invention comprises the steps of bringing a second medium to flow through the slits and out towards the outer surface of the elongated body to affect the first medium flowing by the outer surface while generating a lifting force, and alternate a direction of the second medium flowing out through adjustment of the slits to alternate a direction of the lifting force while bringing the elongated body around the bearing. Hence, the pendulum movement is obtained in an effective manner for further extraction and conversion of energy. Additional features and advantages of the present invention are evident from the description below, enclosed drawings and independent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail by means of exemplary embodiments and with reference to the accompanied drawings, of which

Fig. 1 is a schematic side view of the device according to one em- bodiment of the invention,

Fig. 2 is a schematic front view of the device according to Fig. 1 , Fig. 3 is a schematic side view of the device according to Fig. 1 and Fig. 2, illustrating the pendulum movement of the elongated body, Fig. 4 is a schematic cross section side view of one portion of the device according to the invention, illustrating the inside of one portion of the elongated body and one portion of the transmission of the device,

Fig. 5 is a schematic view from above of the device according to the present invention,

Fig. 6 is a schematic cross section view of the elongated body according to a first embodiment of the present invention,

Fig. 7 is a schematic cross section view of the elongated body according to Fig. 6, illustrating the generation of lifting force in one direction, Fig. 8 is a schematic cross section view of the elongated body according to Fig. 6, illustrating the generation of lifting force in the opposite direction,

Fig. 9 is a schematic side view of one portion of the device according to one embodiment of the present invention, illustrating the slits of the elon- gated body,

Fig. 10 is a schematic cross section view of the elongated body according to a second embodiment of the present invention,

Fig. 11 is a schematic cross section view of the elongated body according to a third embodiment of the present invention, Fig. 12 is a schematic cross section view of the elongated body according to a fourth embodiment of the present invention,

Fig. 13 is a schematic cross section view of the elongated body according to a fifth embodiment of the present invention,

Fig. 14 is schematic cross section views in series of the elongated body according to a sixth embodiment of the present invention,

Fig. 15 is schematic cross section views in series of the elongated body according to a seventh embodiment of the present invention, and

Fig. 16 is schematic cross section views in series of the elongated body according to an eighth embodiment of the present invention. THE INVENTION

In reference to Fig. 1 and Fig. 2 a device 10 for generating a lifting force for extraction of energy from a first medium flowing by according to the present invention is illustrated schematically. The device 10 is, for example, arranged as an energy conversion device or energy extraction device for conversion or extraction of energy from the first medium flowing by. For example, the first medium flowing by is an air flow, such as wind, wherein the device 10 is arranged in the form of a pendulum wind power plant for extrac- tion of energy through generation of a lifting force. The device 10 is, for example, arranged for conversion of wind energy to electric energy. Alternatively, the first medium flowing by is water, wherein the device 10 is arranged as a water power plant.

The device 10 comprises an elongated body 11 having an outer sur- face 12 for affecting the first medium flowing by, wherein the first medium flowing against the elongated body 11 is forced around the outer surface 12 of the elongated body 11 to pass by before it continues in its original direction. Hence, the first medium flows around a circumference of the elongated body 11. The elongated body 11 further comprises a first end 13 and a second end 14. The first end 13 is arranged in a lower portion of the elongated body 11 and the second end 14 is arranged in an upper portion thereof. The first end 13 is connected to the underlayer 15 through a foundation 16 and a bearing 19 arranged in a first support 17 and a second support 18. The first end 13 is also connected to a counterweight 20. Hence, the elongated body 11 is connected to the underlayer 15 through the bearing 19, wherein the elongated body 11 is arranged pivotally around at least one portion thereof. The bearing 19 can be arranged differently, which is obvious for a person skilled in the art. Suitably, the counterweight 20 is arranged with an over- weight compared to the elongated body 11 so that the elongated body can swing around the bearing 19. Suitably, the underlayer 15 is fastened in the underlaying ground so that the device 10 is secured when the elongated body 11 swings. The first support 17 and the second support 18 are connected to the foundation 16 in a lower portion, wherein an upper portion projects in a vertical direction up- wards. The supports 17, 18 are, for example, arranged in parallel, forming a space for the lower portion of the elongated body 11 and the counterweight 20. Suitably, the bearing 19 is arranged in the upper portion of the supports 17, 18 and above the counterweight 20 so that the elongated body 11 is brought to a vertical position when it is not affected by the first medium flow- ing by. The bearing 19 is, for example, formed as a shaft arranged through the supports 17, 18 and the lower portion of the elongated body 11. The second end 14 is a free end, or arranged projecting from the first end 13 and the underlayer 15.

In reference also to Fig. 3 the pendulum movement of the elongated body 11 is illustrated. The device 10 is arranged so that the elongated body 11 can be pivoted around at least one portion of the bearing 19, wherein a pendulum movement can be obtained. This is illustrated by means of the arrow A. In Fig. 3 the elongated body 11 is illustrated in a first end position where it has been turned in a clockwise direction, while bringing the counter- weight along therewith. Further, the elongated body 11 is illustrated in a vertical position and in a second end position, where it has been turned in a counter-clockwise direction due to the first medium flowing by, by means of dash and dot lines. The device 10 is arranged to generate a lifting force perpendicularly to the first medium flowing by, wherein the elongated body 11 is brought to turn around a portion of the bearing 19. When the elongated body 11 cross a predetermined limit position the direction of the lifting force is altered so that the elongated body 11 is brought to accelerate in the opposite direction and, consequently, to turn at a desired end position. Hence, a pendulum movement of the elongated body 11 is obtained, wherein energy can be extracted from the first medium flowing by and be converted to, for example, electric energy. The energy conversion is, for example, obtained by conventional means, such as hydraulics, a generator and similar. Suitably, the elongated body 11 is arranged symmetrically to facilitate the turning in opposite directions around the bearing 19 and to obtain a uniform pendulum movement. For example, the elongated body 11 is arranged in the form of a circular cylinder. Alternatively, the elongated body 11 is ar- ranged with an elliptic cross section or similar.

In reference to Fig. 4 a portion of the device 10 is illustrated partially in cross section. The elongated body 11 comprises a passage 21 for conducting a second medium inside the elongated body 11. For example, the elongated body 11 is hollow so that a second medium, such as air or water, can flow along the extension of the elongated body 11. In the embodiment shown, a device for improving the flow of the second medium is arranged in the passage 21. In the embodiment of Fig. 4 a fan 22 is arranged in the passage 21 to provide or improve the flow of the second medium inside the passage 21. The fan 22 is, for example, arranged in the lower first portion of the elongated body 11. Alternatively, a pump or similar is arranged in the passage 21 to improve the flow of the second medium.

In Fig. 4 the transmission of the device 10 according to one embodiment of the present invention is illustrated schematically, which transmission is arranged for converting the energy from the pendulum movement to, for example, electric energy. The device 10 comprises a first hydraulic cylinder 23 connecting the counterweight 20 and the support 17, 18 and a second hydraulic cylinder 24 connecting the counterweight 20 and the support 17, 18. Alternatively, the hydraulic cylinders 23, 24 are connected to the elongated body 11 and the foundation 16 or in a similar manner so that the hy- draulic cylinders 23, 24 are compressed and pulled apart when the elongated body pendulates. For example, hydraulic cylinders are arranged correspondingly on the opposite side of the device 10, wherein the device 10 comprises four hydraulic cylinders. The hydraulic cylinders 23, 24 are connected to a generator or similar, not illustrated in the drawings, so that the energy can be converted to electric energy or any other form of energy. The transmission of the device 10 is, for example, arranged conventionally. In reference to Fig. 5 the device 10 is illustrated from above. The foundation 16 is connected to the underlayer 15 through a joint means, not illustrated in the drawings, so that the foundation 16 can be pivoted in a horizontal direction. This is illustrated by means of the arrow B in Fig. 5. Hence, the foundation can be pivoted while bringing the supports 17, 18 and the elongated body 11 along therewith, wherein the elongated body 11 can be set according to the direction of the first medium flowing by. Accordingly, the device 10 is adjustable to the direction of the wind so that the elongated body can pendulate perpendicular to the direction of the wind independent of its direction. Alternatively, the device 10 is adjustable according to the direction of a flowing liquid, such as water, so that the elongated body can pendulate perpendicular to it independent of its direction. For example, the device 10 comprises a motor for pivoting the foundation 15 around the joint means. For example, the joint means and the motor are arranged conventionally and is not described any further.

Fig. 6 is a cross section view of the elongated body 11 according to a first embodiment of the present invention. The elongated body 11 comprises a plurality of slits 25 for a second medium flowing out through the slits 25. The second medium flows out towards the outer surface 12 to affect the first medium flowing by, while generating a lifting force. For example, the slits are arranged as a plurality of apertures, such as one or more perforations. The slits 25 connect the passage 21 and the outer surface 12 of the elongated body 11. Thus, the slits 25 are arranged for conducting the second medium flowing inside the elongated body 11 to the outer surface 12. Due to that the first medium flowing by follows the second medium flowing out a lifting force is generated perpendicular to the direction of the first medium flowing by, wherein the elongated body is brought to turn around the bearing 19 in the direction of the lifting force. Suitably, the elongated body 11 is provided with a closing or a cover or similar so that the second medium is forced out through the slits.

The slits 25 are distributed around a circumference of the elongated body 11 to allow generation of lifting force in opposite directions to obtain the pendulum movement. The slits 25 are distributed symmetrically around the elongated body 11 to obtain a uniform pendulum movement. In the embodiment of Fig. 6 of the present invention the device 10 comprises a first set of slits for generation of lifting force in one direction and a second set of slits for generation of lifting force in the opposite direction. The first set of slits is in- dined to a radial direction of the elongated body 11 , wherein the second medium flowing out flows along the outer surface 12 in the direction of the first medium flowing by. Thus, the slits 25 are inclined to the elongated body 11 so that the second medium flows tangentially with the outer surface 12. This is illustrated by means of the arrows C. The second set of slits is arranged correspondingly, which is illustrated by means of the arrows D. The device 10 is arranged so that the direction of the lifting force can be alternated, which is described in more detail below. Alternatively, the slits are arranged with a bend or similar so that the second medium flowing out follows the outer surface 12 or envelope surface of the elongated body 11. For example, the elongated body 11 comprises reinforcements 26 or a frame structure or similar to stabilize the elongated body. The reinforcements 26 are, for example, arranged conventionally.

In reference to Fig. 7 the direction of the lifting force and the first medium flowing by is illustrated when the second medium flowing out flows out from the first set of slits. The direction of the second medium flowing out is illustrated by means of the arrows C, the direction of the first medium flowing by is illustrated by means of the arrows E and the direction of the lifting force is illustrated by means of the arrow F.

In reference to Fig. 8 the direction of the lifting force and the first me- dium flowing by is illustrated when the second medium flowing out flows out from the second set of slits. The direction of the second medium flowing out is illustrated by means of the arrows D, the direction of the first medium flowing by is illustrated by means of the arrows E and the direction of the lifting force is illustrated by means of the arrow G. In reference to Fig. 9 a portion of the device 10 is illustrated perpendicular to the direction of the first medium flowing by. The slits 25 are arranged along the elongated body 11. Hence, the slits 25 extend from a lower portion to an upper portion of the elongated body 11 , or substantially from the first end 13 to the second end 14. Hence, the slits 25 divide the outer wall of the elongated body 1 into a plurality of wall elements. Alternatively, the slits are formed as a plurality of apertures arranged along the longitudinal direc- tion of the elongated body 11. The elongated body 11 comprises at least two slits arranged symmetrically around the circumference of the elongated body so that one slit is arranged on each side. For example, the elongated body comprises four or six slits 25. The slits 25 are distributed around the elongated body 11 to obtain a suitable angle of incidence, i.e. the angle between the direction of the first medium flowing by and each of the slits 25. Alternatively, the elongated body comprises more slits 25. For the stabilization of the elongated body 11 the device 10 comprises reinforcements 26 distributed along the length of the elongated body. Alternatively, the elongated body 11 comprises a frame structure or similar for the stabilization thereof. Fig. 10 is a cross section view of the elongated body 11 according to a second embodiment of the present invention. According to the second embodiment the elongated body comprises four slits 25. Two slits 25 are arranged at one side of the elongated body 11 to generate lifting force in one direction and two slits 25 are arranged at the opposite side of the elongated body 11 to generate lifting force in the opposite direction. The slits 25 are adjustable, wherein a direction of the second medium flowing out can be alternated. Dampers 27 are arranged at each of the slits 25 so that they are adjustable. In other respects the slits 25 are fixed. The dampers 27 are arranged to allow closing of the slits 25, wherein these can be opened and closed to control the direction of the lifting force. The dampers 27 are, for example, connected to the elongated body 11 through joint means or similar, wherein the dampers can be turned towards the slits 25 for closing thereof or from the slits 25 for opening thereof. Consequently, the second medium flowing out can be controlled regarding which slit 25 it should flow out from, wherein the direction of the lifting force is adjustable. In Fig. 10 a first set of slits 25 are open so that the second medium can flow out. This is illustrated by means of the arrows C. For example, the dampers 27 are connected to a conventional motor or similar for opening and closing thereof. Alternatively, the dampers 27 are arranged as slide dampers and the slits as a plurality of apertures arranged along the longitudinal direction of the elongated body 11 , not illustrated in the drawings. Such slide dampers comprise, for example, a plurality of openings separated by means of strips, wherein the slits can be opened and closed by displacement of the slide dampers. Hence, a slit is opened when the openings of the corresponding slide damper are arranged over the apertures of the slit.

Fig. 11 is a cross section view of one portion of the elongated body 11 according to a third embodiment of the present invention. According to the third embodiment the elongated body 11 comprises at least one pivoted wall element 28. The wall element 28 is arranged to allow opening and closing of the slits 25 by turning. The wall element 28 comprises a hinge means 29, wherein the wall element 28 can be turned around the hinge means 29. For example, the hinge means 29 is arranged at a centre portion of the wall ele- ment 28, wherein a slit 25 is opened at one end of the wall element 28 and closed at the opposite end thereof when turned. For example, wall portions arranged adjacent the pivoted wall element 28 comprises a portion 31 projecting towards the pivoted wall element 28. Hence, when the pivoted wall element 28 is turned one end of the pivoted wall element 28 contacts the pro- jecting portion 31 of an adjacent wall portion 30, while a slit is formed at the opposite end. In Fig. 11 the pivoted wall element 28 is turned in a counterclockwise direction. The direction of the second medium flowing out from the formed slit 25 is illustrated by means of the arrow C. For example, the pivoted wall element 28 is connected to a motor or similar for turning the wall element, not shown in the drawings.

Fig. 12 is a cross section view of the elongated body 11 according to a third embodiment of the present invention. According to the third embodiment the elongated body 11 comprises four slits 25. Two slits 25 are arranged at one side of the elongated body 11 to generate a lifting force in one direction and two slits 25 are arranged at the opposite side of the elongated body 11 to generate a lifting force in the opposite direction. A dividing wall is arranged across the passage 21 , wherein the second medium can be directed towards each of the slits 25 or each set of slits. For example, the elongated body 11 comprises a first dividing wall for separating the first set of slits from the second set of slits. Thus, the passage 21 is divided into two chambers for conducting the second medium to each set of slits. For example, the elongated body 11 also comprises a second dividing wall 33, wherein the flow of the second medium to each of the slits is adjustable. Thus, the passage 21 is divided into a first chamber 34, a second chamber 35, a third chamber 36 and a fourth chamber 37 for conducting the second medium to each of the slits 25. By conducting the second medium to each of the chambers 34-37 alternately the second medium flowing out can be controlled with reference to which slit 25 it should flow out from, wherein the direction of the lifting force is adjustable. In Fig. 12 the second medium is conducted to the first chamber 34 and the second chamber 35 so that the second medium can flow out through the slit 25 of the first chamber 34 and the slit 25 of the second chamber 35. This is illustrated by means of the arrows C. Fig. 13 is a cross section view of the elongated body according to a fourth embodiment of the present invention. According to the fourth embodiment the elongated body 11 comprises a plurality of pivoted slits 25, wherein the direction of the second medium flowing out is adjustable. Accordingly the second medium can be brought to flow tangentially along the outer surface 12 of the elongated body, both in a clockwise direction and a counterclockwise direction to alternate the direction of the lifting force. Accordingly, adjustable slits are provided, wherein the direction of the second medium flowing out is adjustable. In Fig. 13 the slits 25 are set so that the second medium flows in a clockwise direction around the elongated body 11 , which is illustrated by means of the arrows C. The direction of the first medium flowing by is illustrated by means of the arrows E and the direction of the lifting force is illustrated by means of the arrow F. The slits 25 may be arranged in a plurality of different manners to obtain the pivoted function and, hence, the alternation of the direction of the lifting force. For example, the elongated body 11 comprises pivoted plates for opening and closing the slits 25. Some examples are described below. The slits or the plates are, for example, connected to a motor or similar for turning thereof, which is not illustrated in the drawings. In reference to Fig. 14 a portion of the elongated body 11 is illustrated according to a fifth embodiment of the present invention. According to the fifth embodiment the elongated body 11 comprises pivoted plates for alternating the direction of the second medium flowing out. For example, the elon- gated body 11 comprises a pivoted first plate 38 and a pivoted second plate 39. Thus, the plates 38, 39 comprise a hinge element 40, around which the plates 39, 40 can be turned. The hinge element 40 is arranged at a first end of each plate 38, 39, wherein a slit can be formed or opened at the second end. The plates 38, 39 are turned to a position in which the second end of the second plate 39 projects outside and by the second end of the first plate 38 to obtain a slit 25 for providing a flow of the second medium in a counterclockwise direction. Hence, a space between the first plate 38 and the second plate 39 is formed. This is illustrated in the top figure in the series of figures. To alternate the direction of the second medium flowing out the first plate 38 is turned in a clockwise direction and the second plate 39 is turned in a counter-clockwise direction until the second end of the plates 38, 39 are directed towards each other. This position is illustrated by the centre figure of the series of figures. Then, the first plate 38 is turned in a counter-clockwise direction and the second plate 39 is turned in a clockwise direction so that the first plate 38 is positioned outside the second plate 39. The turning continues until the second end of the first plate 38 projects outside and by the second end of the second plate 39, which is illustrated in the bottom figure of the series of figures. Accordingly, adjustable slits are provided, wherein the direction of the second medium flowing out can be alternated. In reference to Fig. 15 a portion of the elongated body 11 is illustrated according to a sixth embodiment of the present invention. According to the sixth embodiment the elongated body 11 comprises a pivoted plate element 41 for alternating the direction of the second medium flowing out. The plate element 41 is arranged in a space between a first wall segment 43 and a second wall segment 44 of the elongated body 11. Suitably, a length of the plate element 41 is somewhat longer than the space between the wall segments 43, 44, wherein a first end portion 45 projects by one end of the first wall segment 43 and a second end portion 46 projects by one end of the second wall segment 44. The plate element 41 comprises a joint 42, around which the plate element 41 can be turned. The joint 42 is arranged in a centre portion of the plate element 41 , wherein a slit can be formed or opened at its end portions 45, 46. The plate element 41 is turned to a position in which the first end portion 45 projects outside and by the end of the first wall segment 43 and the second end portion 46 projects inside and by the end of the second wall segment 44 to provide a slit 25 for the outflow of the second medium in a counter-clockwise direction. Hence, a space is formed between the plate element 41 and each of the wall segments 43, 44. This is illustrated by the top figure in the series of figures. To alternate the direction of the second medium flowing out the plate element 41 is turned in a clockwise direction until the plate element 41 is arranged across the extension of the wall segments 43, 44. This position is illustrated by the centre figure in the series of figures. Then, the plate element 41 is turned in a clockwise direction until the first end portion 46 is positioned outside and by the end of the second wall segment 44 and the second end portion 46 is positioned inside and by the end of the first wall segment 43. This is illustrated in the bottom figure in the series of figures. Accordingly, adjustable slits are provided, wherein the direction of the second medium flowing out can be alternated. In reference to Fig. 16 a portion of the elongated body 11 is illustrated according to a seventh embodiment of the present invention. According to the seventh embodiment the elongated body 11 comprises two plate elements 41 for alternating the direction of the second medium flowing out, which plate elements 41 are arranged in parallel and pivoted by means of joints 42. One plate element 41 is arranged on the inside of the outer wall of the elongated body 11 and one plate element 41 is arranged on the outside thereof. Accordingly, both of the plate elements 41 are pivoted so that a slit can be formed in each direction. This is illustrated in the series of figures of Fig. 16.

Claims

1. A device for generating a lifting force for extraction of energy from a medium flowing by, comprising an elongated body (11) having an outer surface (12) for affecting a first medium flowing by, a first end (13) connected to an underlayer through a bearing (19) and a free second end (14), wherein the elongated body (11 ) is arranged pivotally around at least one portion of the bearing (19), c h a ra c t e ri s e d by

that the elongated body (11) comprises a plurality of slits (25) for a second medium flowing out through the slits (25), wherein the second medium flows out towards the outer surface (12) to affect the first medium flowing by the outer surface (12) while generating a lifting force, and

that the slits (25) are adjustable, wherein a direction of the second medium flowing out is adjustable for alternating a direction of the lifting force while bringing the elongated body (11) around the bearing (19).

2. A device according to claim 1 , wherein the elongated body (11 ) is symmetric for uniform distribution of the lifting force in alternating directions.

3. A device according to claim 2, wherein the elongated body (11 ) is arranged as a circular cylinder.

4. A device according to claim 1 , wherein the slits (25) are arranged in an inclined angle towards a circumference of the elongated body (11 ) so that the second medium flowing out is brought to flow tangentially along the outer surface (12) of the elongated body (11).

5. A device according to claim 1 , wherein the elongated body (11 ) comprises a fan (22) and a passage (21 ) arranged in at least one portion of the longitudinal direction of the elongated body for conducting the second medium from the fan to the slits (25) and wherein the slits (25) connects the passage (21 ) and the outer surface (12) of the elongated body (11 ).

6. A device according to claim 1 , wherein the elongated body (11 ) comprises a displaceable or pivoted means (27, 28, 38, 41 ) or a dividing wall (32, 33) for adjustment of a direction of the second medium flowing out.

7. A method for generation of lifting force for extraction of energy from a medium flowing by, comprising an elongated body (11 ) having an outer surface (12) for affecting a first medium flowing by, a first end (13) connected to an underlayer through a bearing (19) and a free second end (14), wherein the elongated body (11 ) is arranged pivotally around at least one portion of the bearing (19), comprising the steps of

bringing a second medium to flow through a plurality of slits (25) and out towards the outer surface (12) of the elongated body (11 ) to affect the first medium flowing by the outer surface (12) while generating a lifting force, and

adjusting a direction of the second medium flowing out through adjustment of the slits (25) to alternate a direction of the lifting force while bringing the elongated body (11 ) around the bearing (19).

8. A method according to claim 7, wherein the second medium flowing out is brought to flow tangentially along the outer surface (12) of the elongated body (11 ) by arranging the slits (25) in an inclined angle towards a circumference of the elongated body (11 ).

9. A method according to claim 7, wherein the second medium is brought to flow in a passage (21 ) arranged in at least one portion of the longitudinal direction of the elongated body (11 ) by means of a fan (22).

10. A method according to claim 7, wherein a direction of the second medium flowing out is adjusted by means of a displaceable or pivoted means (27, 28, 38, 39, 41 ) or a dividing wall (32, 33).