Helical rotor for wind turbines with increased efficiency

Abstract

2.1 Conventional drag rotors have convex or concave rotor blades. While the concave turbine parts generate torques acting in the direction of rotation, the convex turbine parts generate torques opposing the rotation. Since the torque responsible for rotation is the difference between the two, the efficiency of such wind turbines is low. The minimum wind speed required for reliable turbine rotation also presents a problem. The new device is intended to generate electrical energy with greater efficiency, even at low wind speeds. 2.2 The device comprises a helical turbine (2) connected to a generator (1). An air guide (5) on the windward side accelerates incoming air masses and, thanks to its rectangular shape, directs them to those blades (3) of the turbine (2) that move with the wind. This baffle prevents convex blades from being impacted by the incoming air. Additionally, outer baffle elements (8) are connected to their respective blades and exhibit a concave shape as they move with the wind direction. 2.3 Due to its vertical axis of rotation, the rotor can be used in small wind turbines for decentralized energy systems.

Description

[0001] The invention relates to a rotor for wind turbines with shields for the blades running against the wind, consisting of a helical wind turbine with a rotation axis that is essentially perpendicular to the wind direction or adjustable, as well as additional concave-shaped cladding elements at the ends of the blades.

[0002] Helical rotors and inlet funnels for wind turbines are known from the state of the art, see, among others, EP 1 925 819 A1, BE 1016069 A3, DE 29 31 983 A1.

[0003] For large-scale energy generation, uplift rotors with a predominantly horizontal axis of rotation are used. These are relatively efficient but have large diameters to harvest larger portions of the wind. This design, however, results in very high blade tip speeds. Wind turbines of this type are therefore only suitable for use outside of populated areas; they must be mounted on tall masts with expensive foundations, thus posing a danger to birds and other living creatures. These widespread wind turbines also pose a problem for many people due to their impact on the overall landscape. Added to this is the technical challenge that the generated electrical energy must be transported over long distances, which is fraught with losses, due to their location far from the households or industrial facilities that use it.

[0004] Therefore, for converting wind energy into electrical energy near built-up areas, systems with turbine axes essentially perpendicular to the wind direction are more suitable. Common wind turbines of this type are generally resistance rotors. They consist of rotor blades arranged offset from one another and moving in opposite directions. Common designs include those blades that rotate against the wind and are convex, while those that rotate with the wind are concave.

[0005] The concave parts of the turbine generate a torque that acts in the direction of the desired rotation, whereas the blades moving against the wind generate weaker torques that counteract the desired rotation. Since the torque responsible for rotation is the difference between the two, the efficiency of such wind turbines is relatively low. The minimum wind speed required to achieve reliable turbine rotation also presents a problem.

[0006] The invention presented here is based on the object of converting the flow energy of the wind into rotational energy with higher efficiency and even at very low wind speeds by means of a turbine whose axis is perpendicular to the wind direction, and into electrical energy by means of an integrated generator.

[0007] For this purpose, the portion of the incoming flow that hits the convex-shaped turbine parts and weakens the actual torque can be prevented from reaching the wind turbine. DE 30 45 826 A1 describes a Savonius rotor that shields the turbine side rotating against the wind by using so-called wind deflectors or wind inlet slopes. The effectiveness of such deflectors is limited to turbine shapes whose long sides of the blades run parallel to the axis of rotation. The turbine parts to be shielded are polygons, in the simplest case rectangles. However, such shapes only offer the wind a resistance surface temporarily during rotation, resulting in uneven running. With spiral rotor blades, as found in helical rotors, a permanent propulsive torque can be generated. However, here turbine surfaces whose shape changes during rotation must be shielded.This is not provided for in DE 30 45 826 A1.

[0008] According to the basic idea of ​​this invention, the object is achieved by a device which has a helical turbine (2) connected to a generator (1). An air guiding device (5) on the side facing the wind accelerates incoming air masses and, thanks to its rectangular shape and its position to one side of the rotational axis, guides them to those blade vanes (3) of the turbine (2) which move with the wind. This baffle prevents blade vanes moving against the direction of the wind from being hit by the incoming air. This prevents a braking torque, so that efficiency increases and even lower wind speeds allow the rotor to start up.

[0009] However, due to the helical shape of the blades, parts of the blades located within the flow window and convexly curved within the rectangular opening (4) of the air guiding device (5) are also impacted. These could exert a braking torque on the turbine if they did not have external shrouds (8). These rotor blade extensions are connected to their respective blades and exhibit a concave shape as they move with the wind direction. As a result, air masses in this surface area of ​​the flow window (4) can also contribute to the acceleration of the turbine (2).

[0010] The Fig. 1, Fig. 2 and Fig.3 show a preferred embodiment of the wind turbine (2) with additional concavely shaped facing elements (8) at the ends of the blade vanes (3) in various views. The wind inlet slopes (5) are designed here in the form of a three-dimensional flow funnel in order to concentrate the largest possible proportion of air mass onto the concave turbine sections. To maintain the flow velocity, the guide device is shaped as an enclosing hollow cylinder (6), on the leeward side of which a further window (7) is provided, which releases the air masses from the wind turbine. Due to the need to adapt the air guide device (5) to the current wind direction, the hollow cylinder (6) is mounted so as to be rotatable about a vertical axis that a weather vane (9) rigidly attached to it ensures automatic alignment.During rotation of the turbine (2), the concavely shaped facing elements (8) at the ends of the blade vanes assume propulsion precisely when one blade vane leaves the area of ​​the inflow window (4), while a following blade vane is not yet exposed to airflow at its concave blade portion (3). This ensures continuous drive of the helical turbine (2), allowing the generator (1) to achieve a higher average output over time. List of reference symbols 1 generator 2 wind turbines 3 blade vane 4 Air intake 5 Air guiding device 6 Veneer 7 Air outlet 8 veneer element 9 Wind vane

Claims

[1] Rotor for wind turbines with shields (5) for the blades running against the wind, consisting of a helical wind turbine (2) with an axis of rotation substantially perpendicular to the wind direction, wherein at least one blade (3) carries an outer covering element (8), characterized by that the outer facing elements (8) offer the oncoming wind a concavely curved attack surface at least temporarily during one rotation, while the blade vanes (3) have a convex shape in this direction, wherein during one rotation of the turbine (2) the concavely shaped facing elements (8) at the ends of the blade vanes take over the propulsion precisely when one blade vane is already leaving the area of ​​the inflow window (4), while the following blade vane (3) is not yet being flowed onto at its concave blade part (3). [2] Rotor for wind turbines according to claim 1, characterized bythat the shield (5) for the blade vanes running against the wind is designed as a three-dimensional flow funnel. [3] Rotor for wind turbines according to claim 1 or 2, characterized by that the shields (5) for the blade vanes running against the wind are designed as a hollow cylinder (6) enclosing the circumference with air inlets and outlets (4) and (7).

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