WO2012031968A1 - Electrical generator and rotor blade assembly - Google Patents

Abstract

The invention relates to a vertical rotor blade assembly (20) which comprises a cylinder (22) and at least two rotor blades (24, 25, 26, 44, 45) which are mounted perpendicularly to the circular plane of the cylinder on the circumference of the cylinder (22), wherein the edge of each rotor blade surface (24, 25, 26, 44, 45) bears directly against the cylinder (22).

Description

 Electric generator and rotor blade assembly

The invention relates to an electric generator for wind power and other flow power plants. Furthermore, the invention relates to a rotor blade arrangement for wind power and other flow power plants.

PRIOR ART Today's wind turbines mostly use rotor heads mounted on a high tower with vertically mounted rotor blades. Most systems operate on the flow principle, so with rotor heads or turbines, which is traversed by air or other fluids. Such plants currently achieve efficiencies of about 40%. A large part of the impinging flow energy can therefore not be exploited.

Of course, the goal in all generator sets is to convert the energy used into electricity as efficiently as possible. It must also be considered that at times only very low wind / flow velocities can be present or that at different heights differently strong currents can exist, or that currents can even run in different directions. This applies to wind turbines as well as other plants, such as tidal or hydroelectric power plants.

Generators are known from the prior art, in which instead of rotor and stator two opposing coaxial rotors are used to increase the effective speed of the generator. However, these generators can only work in opposite directions. In addition, the associated drive rotors are included When using these generators, wind turbines are usually mounted one behind the other in the flow, so that only an attenuated flow can be utilized at the second rotor. Such a system is described for example in the application DE 10 2008 053 012.

Summary of the invention

According to a first embodiment of the invention, there is disclosed a generator comprising: at least one flat fixed stator; at least two disc-shaped planar rotors, wherein a rotor is mounted above and a rotor below the stator substantially parallel to the stator, wherein the rotors are rotatably mounted about a common axis of rotation, wherein the rotors are drivable in the same direction or in opposite directions. In one embodiment, the generator comprises at least one additional planar stator, which is mounted above and / or below the rotors, wherein the at least one additional stator is optionally switchable. Each rotor may be provided with at least two permanent magnets, and the stators or the stator may be provided with windings which are suitable for the induction of an electrical voltage.

According to a further embodiment of the invention, a vertical rotor blade assembly is disclosed, comprising a cylinder, and at least two rotor blades, which are mounted perpendicular to the circular plane of the cylinder on the circumference of the cylinder. The rotor blades are mounted so that an edge of the rotor blade surface in each case completely and directly adjoins the cylinder. In one embodiment, the cylinder diameter is at least 2/3 of the overall diameter of the assembly. The cylinder may be formed as a hollow cylinder or solid cylinder. The rotor blades may extend in an exemplary embodiment substantially over the entire length of the cylinder. According to a further embodiment of the rotor blade assembly, each rotor blade is divided over the length of the cylinder into at least two parts, wherein the rotor blade parts are mounted offset on the cylinder circumference. Alternatively, the cylinder may be divided into at least two parts, which are arranged axially offset. The rotor blades may be flat, curved or formed as a spherical shell section.

According to a further embodiment, there is disclosed a turbofan plant comprising a generator as described above and two rotor blade assemblies as described which are connected to the generator so that each one rotor of the generator can be driven by a rotor blade assembly.

With such rotor blade assemblies, which operate vertically according to the backflow principle instead of the flow-through principle, more energy can be generated with much smaller plants. Shadow and background noise are reduced by the design.

Short description of the drawing

In the following, exemplary embodiments of the description will be described in more detail with reference to the figures.

It shows

 1 shows a cross section of a generator according to an embodiment of the invention, FIG. 2 shows a cross section of a further generator according to an embodiment of the invention with additional stators,

 Figure 3 shows an exemplary rotor blade assembly according to the invention in cross-section (Figure 3a) and longitudinal section (Figure 3b).

 FIG. 4 a further exemplary rotor blade arrangement with three-part, offset rotor blades in an oblique view,

 5 shows a further rotor blade arrangement with offset cylinder sections in an oblique view,

Figure 6 shows an exemplary wind turbine with tower and two separate Rotor blade assemblies in cross section, and

 Figure 7 shows another exemplary wind turbine with two opposing rotor blade assemblies with curved rotor blades in plan view and oblique view.

Detailed description of exemplary embodiments

FIG. 1 shows a cross section of a generator 1 according to an exemplary embodiment. Rotors and stators are inventively disc-shaped. In the example, a fixed stator 2 in the form of a surface or disc between two rotatable disc-shaped rotors 4, 6 is arranged. The two rotors 4, 6 are independently rotatable and arranged substantially parallel to the stator 2. A rotor 4 is located above, the other 6 below the stator 2. Rotor and stator are at a small distance from each other, but do not touch. The two rotors 4, 6 can rotate at different speeds in the same or opposite direction. The rotors are arranged substantially coaxially. The drive shafts 7, 8 of the rotors 4, 6 may be designed so that a first shaft 7 extends inside the hollow second shaft 8. Stator and rotors may be surrounded by a generator housing 9, as shown by way of example in the figure. At the contact points between the stator and shaft or between the first and second rotor shaft bearing elements 5 are respectively provided, which allow a loss-free as possible rotation of the shafts / rotors, such as radial bearings of any embodiment.

The generator may be provided with sliding contacts or brushes or be designed as a brushless generator. In this case, the voltage can be indexed either in the rotor 4, 6 or in the stator 2. In an exemplary embodiment, a magnetic field is provided by the rotors, which is achieved for example by permanent magnets, which are arranged in each case alternately on the circular rotor surface 4, 6. In this case, magnets may be mounted on both sides of the rotor or individual magnets may be mounted in through openings of the disc; Similarly, the magnets may be mounted only on one surface of the rotor. In practical embodiments, a large number of magnets may be used, which are arranged along the circumference of the rotor. When Material can be used for example ferrite magnets or rare earth magnets.

Alternatively, electrically driven induction loops for generating the magnetic field may be used in the rotors instead of permanent magnets. The advantage of such a design, especially in large systems is that a force-dependent control is possible. Thus, the magnetic field strength at low wind speeds or when starting the generator can be kept lower and increased later. In this way, the entire system can be variably adapted to different flow forces, for example, to keep the starting resistance low. Since the two rotors are independent of each other, the magnetic field strengths in this case can also be adjusted separately for each rotor. In systems with permanent magnets, especially in small systems, a similar control can be achieved easily by regulating the distance between the rotor and stator. For example, the rotors may be movably mounted in the axial direction.

The stator 2 may be provided with windings in which a voltage is indicated during operation of the generator. For example, the windings may be flat, copper or aluminum wire windings embedded parallel to the rotor plane, but also printed windings on the stator plate surface. In an exemplary embodiment, the stator surface may be provided with regularly arranged through openings into which finished windings can then be inserted. Thus, a variable construction is achieved, and windings can be easily replaced or changed. In other embodiments, the stator may be provided with integrally formed or attached projections around which the windings pass. Also, baked enameled wire or similar materials can be used to make iron-free self-supporting coils in disc form. The current induced in the coils can be dissipated by a commutator. The remaining details of a generator plant for the use of induced currents and disc rotors are known in the art and can be applied here in the usual way. In an optional embodiment, the stator 2 may be insulated in cross-section so that the two surfaces of the stator are electromagnetically shielded from each other. In this case, separate windings may be disposed on both the upper and lower surfaces of the stator. Thus, a voltage is induced independently on both sides of the stator. The resulting separate generator elements, once with rotor 4 and once with rotor 6, can be connected in parallel or in series depending on the application. Similarly, optionally, the rotors 4, 6 could include an insulating layer. Depending on the design of the generator, this can help to avoid undesired interactions such as eddy currents during induction due to different directions of rotation and speeds of the two rotors.

FIG. 2 shows a further exemplary embodiment of a generator according to the invention. In this embodiment, two additional stators 12, 13, respectively above and below the rotor-stator arrangement of Figure 1 are shown. Likewise, only one of the additional stators 12 or 13 could be present. Thus, the rotor disk 4 is now between the stator surfaces 2 and 12, while the rotor disk 6 between the two stator 2 and 13. As in the original case of Figure 1, a voltage can be induced in the additional stators by the rotation of the rotor disks. As an optional variant, the additional stators could be flexibly connected as needed or disconnected from the system to reduce or increase the voltage yield depending on the flows utilized. In this way, without significant structural change, only by the additional stators, the efficiency of the generator can be increased. The generator according to the invention could also be designed so that a voltage is induced in windings of the rotors, while the magnetic field is built up by permanent magnets on the stator. In this case, however, brushes or sliding contacts are needed to remove the tension. The above statements on windings and magnetic field means are equally applicable here. Another option is a structure in which the permanent magnets together with the windings on the stator are provided, while the rotors are designed as field closing means, for example as a massive iron disc. For this purpose, the rotor disk can be structured so that it is provided on the circular surface with regular elevations, so that at these points the air gap to the stator is minimal and the magnetic field is controlled accordingly. For example, radial struts could be evenly spaced on the plate, with the number of struts corresponding to the number of permanent magnets.

The described generators according to the invention can be installed in all variants with any equipment in which two separate rotor blade assemblies are present. Conceivable are both horizontal and vertical rotor blade assemblies. The rotor blade assemblies can be arranged one behind the other in the same flow path or in different flow paths. In each case, a rotor blade assembly for driving a rotor of the generator is provided. Whether the rotors are driven in the same or in the opposite direction can be determined by the design of the rotor blade assemblies. For example, two separate but similar rotor blade assemblies could be arranged so that the second rotor blade assembly would be mounted in exactly the opposite way. In this way, an opposing drive is automatically realized. FIG. 3 shows a rotor blade arrangement 20 with a vertical axis of rotation according to the invention in cross-section (FIG. 3a) and longitudinal section (FIG. 3b). In this example, three rotor blades 24, 25, 26 are mounted at preferably uniform spacing on a central closed cylinder 22. Depending on the embodiment, only two rotor blades or more than three rotor blades may be attached to the cylinder 22. It is a rotor blade assembly according to the resistance principle, wherein in addition the reverse flow principle is utilized. Inflowing air impinges on the rotor blade 24, 25, 26, which is moved by the flow pressure according to the Wider stand principle; However, the air also flows back along the cylinder surfaces and generates there a negative pressure or overpressure, which causes a rotation of the cylinder. The rotor blades may have a flat or curved shape, such as in the form of cylindrical sections or spherical shells. The The axis of rotation is usually vertical in the flow, ie in the wind.

Preferably, the cylinder diameter is about 2/3 of the total diameter of the rotor blade assembly in cross section, so that the rotor blades 24, 25, 26 have a width of about 1/3 of the radius, as indicated in Figure 3a. In this way, the backflow forces can be optimally utilized on each individual sheet. The coaxial cylinder 22 may be made solid or hollow; For reasons of weight, a hollow cylinder is preferred. Depending on the structure of the overall construction, however, a higher internal weight may be desired in order to influence the center of gravity or the rotational behavior of the system. It is clear to the person skilled in the art that the internal structure of the cylinder can be designed as desired, depending on the requirements. For example, struts could be provided for reinforcement, the cylinder could be attached to the rotor head at one or more points on the shaft, and the cylinder could be made open and / or closed at the bottom or closed. As can also be seen from FIG. 3, the rotor blades 24, 25, 26 may be curved or shaped in a similar manner to a spherical shell-shaped cutout. Advantageously, the rotor blades are mounted so that all curvatures point in the same direction. Even with flat rotor blades, the corners can be rounded both at the outer edge and in the contact area with the cylinder in order to improve the flow characteristics. This embodiment is outlined in Figure 4 as a dashed line. Depending on the application, however, a flat shape of the rotor blades may also be desirable.

The rotor blades may be connected to the cylinder in any suitable manner; For example, they can be welded, screwed or plugged into the cylinder. The person skilled in the corresponding production methods and suitable materials are known, such as metals or plastics that can withstand the acting flow forces.

In a further embodiment of the rotor blade assembly according to the invention, the rotor blades can be divided in the vertical direction into several parts, which are arranged slightly offset around the cylinder 22 around. Such an arrangement is outlined in FIG. In In this example, each rotor blade 33, 34, 35 is divided into three parts 33a, 33b, 33c, 34a, b, c, 35a, b, c. The staggered arrangement of the rotor blades ensures a more uniform absorption of the flow forces and thus less imbalance in operation, so that the load on the components is in turn substantially reduced.

In an alternative embodiment, not only the rotor blades, but the entire rotor blade assembly including the central cylinder are divided into three and offset around the axis of rotation around. Rotor blades of different widths are therefore attached to each cylinder section. In Figure 5, this example is outlined in an oblique view. This arrangement also has the advantage that the currents are absorbed better and the loads are better distributed over the entire arrangement. Both in the embodiment of Figure 4 and in that of Figure 5, the rotor blades may turn be formed flat or curved; Similarly, the corners may be rounded, which is not shown in the figures for simplicity.

According to one embodiment of the invention, a wind turbine can be equipped with a generator as in Figures 1 or 2 and two rotor blade assemblies as in Figure 3 (or following). FIG. 6 shows such a wind turbine according to an exemplary embodiment of the invention. Two rotor blade assemblies with a vertical axis of rotation are mounted one above the other on a tower or mast 50. In the upper part of the mast is the generator 1, which can convert the rotational movement of the two rotor blade assemblies by induction into electricity. The generator could be a generator 1 according to the invention as described in FIGS. 1 and 2; but any other suitable generator can alternatively be used. From the generator 1 extend the two drive axles 7, 8 of the rotors (not visible), which are each connected to a rotor blade assembly 20. The axles may extend over the entire length of the rotor blade assembly or may be attached only to a portion thereof. The system shown is gearless. In the example shown, in both rotor blade arrangements, the cylinder 22 is designed as a hollow cylinder, on whose outer circumference the rotor blades 24, 25 extend over the entire length. The two free-running rotor heads 20 act in this construction in opposite directions, since the second rotor head and the second rotor blade assembly is disposed relative to the first rotor head simply in the opposite direction. The opposing rotation neutralizes the moments of inertia, which normally act as static loads on one side of the overall structure. The opposite rotation of the two superimposed rotor blade assemblies in this example thus improves the statics of the entire system and ensures less material stress for less failure. Each of the two superposed rotor blade assemblies is in this case responsible for the operation of one of the two rotors. However, it is also conceivable to combine the generator according to the invention with disc-shaped stators and rotors with other rotor blade arrangements or turbines, for example with rotor heads with a horizontal axis. Likewise, the rotor blade assembly according to the invention with any generators can be combined, for example, with a conventional generator with two counter-rotating rotors without additional stator.

Figures 7a and 7b show another exemplary embodiment of a wind turbine according to the invention with exemplary rotor blade assemblies. Figure 7a shows the system in an oblique view from below, while Figure 7b outlines the top view of the two rotor blade assemblies. Again, two rotor blade assemblies are mounted on a mast 50. In the mast run two internal shafts (not shown), which are each connected to a rotor blade assembly. Each rotor blade arrangement comprises a cylinder 22 and three rotor blades 44, 45, which are arranged regularly around its circumference and bear directly against the cylinder 22. In the case shown, the rotor blades 44, 45 are curved so that they correspond to open sections of a ball shell flattened on both sides or a hollow lentoid. The openings of the rotor blades 44 of a first rotor blade assembly are arranged opposite to the openings of the rotor blades 45 of the second rotor blade assembly, so that the two rotor blade assemblies 44, 45 will rotate in an impinging flow opposite to each other. Lie again the rotor blades with a peripheral edge completely on the inner cylinder 22 at. Below the mast, in turn, a generator 60 is mounted, by means of which the rotational movement of the two rotor blade assemblies is converted into electrical energy. It is obvious that the above-mentioned components can be used both for wind power plants and for other flow power plants. For example, tidal power plants or ocean current power plants can be equipped with generators and / or rotor blade assemblies according to the invention. Due to the vertical axis of rotation, the direction of flow plays no role, which is advantageous for tidal power plants, for example. Likewise, various flow forces, such as wind and ocean currents or wave power, could be exploited in combination by attaching one part of the plant with one rotor head above the water level and the other part of the plant below the water level. When using the generator according to the invention, both flows can nevertheless be converted into electrical power with a single generator. Since the two rotors rotate independently of each other, both the speed and the direction of two flows can be different, without negatively affecting the operation.

Other variations and combinations of the above examples will be apparent to those skilled in the art, which are also within the scope of the invention.

Claims

Claims: A vertical rotor blade assembly (20) comprising  a cylinder (22), and  at least two rotor blades (24, 25, 26, 44, 45) which are mounted perpendicular to the circular plane of the cylinder on the circumference of the cylinder (22),  wherein the edge of the rotor blade surface (24, 25, 26, 44, 45) in each case directly against the cylinder (22). 2. Rotor blade assembly according to claim 5, wherein the cylinder (22) is designed as a hollow cylinder. 3. Rotor blade assembly according to claim 5 or 6, wherein the rotor blades (24, 25, 26, 44, 45) extend substantially over the entire length of the cylinder (22). A rotor blade assembly according to any one of claims 5 to 7, wherein each rotor blade (33, 34, 35) extends across the length of the cylinder into at least two parts (33a, 33b, 33c, 34a, 34b, 34c, 35a, 35b, 35c). divided, and wherein the rotor blade parts are mounted offset on the cylinder circumference (22). 5. Rotor blade assembly according to one of claims 5 to 8, wherein the rotor blades are flat, curved or formed as a spherical shell portion. 6. generator (1) comprising  at least one flat fixed stator (2); at least two disc-shaped planar rotors (4, 6), wherein a rotor (4) above and a rotor (6) below the stator (2) substantially parallel to Stator is attached,  wherein the rotors (4, 6) are rotatably mounted about a common axis of rotation, wherein the rotors (4, 6) are drivable in the same direction or in opposite directions. 7. Generator according to claim 6, further comprising at least one additional planar stator (12, 13) which is mounted above (12) and / or below (13) of the rotors, wherein the at least one additional stator is optionally switchable. 8. Generator according to claim 6 or 7,  wherein each rotor (4, 6) is provided with at least two permanent magnets. 9. Generator according to claim 6 or 7, wherein the stator (2, 12, 13) is provided with windings, which are suitable for the induction of an electrical voltage. 10. flow power plant, comprising  a generator (1) according to any one of claims 6 to 9,  and two rotor blade assemblies (20) according to any one of claims 1 to 5, which are connected to the generator (1) such that each one rotor (4, 6) of the generator (1) can be driven by a rotor blade assembly (20).