Wind turbine

Abstract

The invention relates to a wind turbine comprising a number of airfoil-type drive blades (10-a to 10-j) which are guided in a circulating manner on a continuous guide track (12) and which can be positioned with respect to the direction of the wind (W) such that the drive blades exert, on a force transmission element (20) that is drivingly connected to a machine (28) to be driven, a propulsive aerodynamic force which acts in a consistent circulating direction. The invention is characterized in that the guide track (12) has two main branches (14, 16) which can be positioned obliquely to the direction of the wind (W) in opposite directions and which are connected together at both ends via a respective connecting branch (18), and in that the drive blades extend transversely to the guide track (12) at least on the main branches (14, 16) and, depending on their current position on the guide track, can be adjusted between two angular positions which are rotated relative to each other about an axis running in the direction of movement of the drive blades.

Description

[0001] WIND TURBINE

[0002] The invention relates to a wind turbine with a number of wing-like drive blades which are guided in rotation on an endless guideway and which can be adjusted with respect to the wind direction in such a way that they exert an aerodynamic propulsive force acting in a uniform direction of rotation on a power transmission element which is in driving connection with a machine to be driven.

[0003] An example of a wind turbine of this type is described in US Pat. No. 6,072,245 A. In this known wind turbine, the guideway has an ascending main branch and a parallel descending main branch. On the ascending main branch, the drive blades are positioned so that their leading edge is higher than the trailing edge, so that the wind pressure generates an upward force component.

[0004] Propulsion blades have an airfoil that is more curved on the upper side than on the underside. Therefore, the Bernoulli effect increases the upward force on the ascending branch. On the descending branch, the propulsion blades are angled so that the leading edge is lower than the trailing edge, so that the wind pressure creates a downward force, i.e. a force that is also directed forward in the direction of rotation of the propulsion blades. However, the Bernoulli effect here creates an upward component, with the result that the propulsive force on the descending branch is smaller than on the ascending branch. In principle, it is possible to turn the propulsion blades at the reversal points of the guideway so that the more curved side of the propulsion blades is always on the correct side. However, the solutions known to date require a complex and failure-prone turning mechanism.

[0005] The object of the invention is to create a wind turbine operating according to the principle described above, which achieves high efficiency with a simplified control mechanism for the drive blades.

[0006] This object is achieved according to the invention in that the guideway has two main branches which can be adjusted in opposite directions obliquely to the wind direction and which are connected to one another at both ends via a respective connecting branch, and in that the drive blades extend at least on the main branches transversely to the guideway and, depending on their current position on the guideway, can be adjusted between two angular positions which are rotated relative to one another about an axis running in the direction of movement of the drive blades.

[0007] Since the two main branches run in opposite directions at an angle to the wind direction, an optimal adjustment of the drive blades is achieved on each main branch. However, the two main branches must be offset from each other in the direction perpendicular to the wind direction and perpendicular to the main branches so that the drive blades moving on one main branch do not collide with the other main branch. If the drive blades were rigidly mounted on the power transmission element, e.g. a drive belt, the aforementioned offset between the main branches would result in the drive blades having to move along a curve on the connecting branches and then, when they rejoin the main branch, would no longer be correctly oriented relative to the wind direction. This problem is solved according to the invention in that the drive blades are adjustable about an axis running in their direction of movement.For example, if the drive blades move along a 90° arc on each connecting branch, they would be aligned approximately parallel to the wind direction upon re-entering the main branch. By then rotating the drive blades 90° around the axis running in the direction of movement, the orientation perpendicular to the wind direction can be restored.

[0008] Adjusting the drive blades relative to the power transmission element thus involves a simple rotation around an axis defined by the path of the power transmission element's guideway, eliminating the need for complex control mechanisms. The rotatable arrangement of the drive blades on a fixed axis relative to the power transmission element also enables stable mounting of the drive blades, which can withstand even high wind loads and avoids high bending moments of the drive blades.

[0009] Advantageous embodiments of the invention are specified in the subclaims.

[0010] In the following, an embodiment example is explained in more detail using the drawing.

[0011] They show:

[0012] Fig. 1 is a schematic side view of a wind turbine according to the invention, which has a guideway for drive blades; Fig. 2 is an isometric view of the guideway;

[0013] Fig. 3 the guideway in plan view,

[0014] Fig. 4 the guideway in a view in the direction of arrows IV-IV in

[0015] Fig. 3;

[0016] Fig. 5 the guideway in a view along the arrows VV in Fig. 3; and

[0017] Fig. 6 shows a guide track according to another embodiment.

[0018] The wind turbine shown in Fig. 1 has a number of wing-like working blades 10-a to 10-j, which are guided circumferentially on an endless guideway 12. The guideway 12 has two main branches 14, 16, which are inclined in opposite directions—in the example shown, by the same angle—against the wind direction W. For example, the wind turbine can be installed so that the main branch 14 is an ascending branch and the main branch 16 is a descending branch. At the ends, the two main branches are connected to each other by connecting branches 18, 18'. The guideway can be formed, for example, by a square tube or a round tube, which accommodates a power transmission element 20 in the form of an endless traction cable, of which only a portion is indicated here by dashed lines.The drive blades are each connected to the power transmission element 20 by a holder 22 in the area of ​​their rounded leading edge and by a holder 24 in the area of ​​their trailing edge. Due to the inclined position of the main branches of the guideway—and in the example shown, also due to the inclined position of the drive blades relative to the guideway—the drive blades are always oriented such that the wind pressure generates an upward force on the ascending branch and a downward force on the descending branch. This force is transmitted via the power transmission element 20 and a cable pulley 26 to a machine 28, for example, a generator for generating electricity. Alternatively, the guideway can also be a generator for generating electricity designed like a linear motor.

[0019] The two main branches 14 and 16 are offset from each other in the direction perpendicular to the plane of the drawing in Fig. 1 so far that the rotating worksheets do not coincide with the

[0020] guideway or collide with each other.

[0021] Fig. 2 shows the guideway 18 in an isometric view. To clarify the geometry of the guideway, a cuboid 30 is also shown. The two main branches 14 and 16 are located in parallel side surfaces of the cuboid 30, while the connecting branches 18, 18' are located in the top surface and bottom surface of the cuboid, respectively.

[0022] Fig. 3 shows a plan view of the guide track 12. This shows the upper connecting branch 18, the right-hand end of which in Fig. 3 adjoins the upper end of the ascending branch 14. However, only the lower end of this ascending branch is visible in Fig. 3, as the remainder of this branch is concealed by a leg of the connecting branch 18. This leg of the connecting branch merges via a 90° bend 32 into another leg, which bends downwards at the opposite end and merges into the descending branch 16. This descending branch 16 bends back into the horizontal plane at the lower end and merges with a further 90° bend 34 into a leg of the lower connecting branch 18'. At the other end, this leg merges into another 90° bend 36 into another leg, which at the end bends upwards again and merges into the ascending branch 14.

[0023] Fig. 4 shows the guide track 12 in the same view as Fig. 1. In the view in Fig. 5, the offset of the two main branches 14, 16 can be clearly seen. The descending branch 16 appears rounded at the ends because the arcs with which it merges into the upper and lower connecting branches 18, 18' lie in planes perpendicular to the direction of view, namely in the left and right side surfaces of the cuboid 30 in Fig. 2. The ends of the ascending branch 14, on the other hand, do not appear rounded because the arcs with which this branch merges into the connecting branches lie in a plane parallel to the direction of view.

[0024] In Fig. 1, the drive blades 10-a and 10-b move upward on the ascending branch 14. The angle of attack at which the air flows against these drive blades is determined by the vectorial superposition of the wind speed vector with the vector of the drive blades' proper motion. At this angle of attack, the air passes over the curved airfoil profiles in such a way that the Bernoulli effect generates a force perpendicular to the surface of the drive blade. Due to the inclined position of the ascending main branch 14, this force has a vertical component that supports the upward movement of the drive blade. The drive blade 10-c is just transitioning into the upper connecting branch 18, and the drive blade 10-d is located on the first leg of this connecting branch. The drive blade 10-e has passed through the 90° bend 32 (Fig. 3) and is now located on the second leg of the connecting branch 18.Due to the 90° rotation, this drive blade is seen from the front in Fig. 1. The drive blade 10-f has entered the descending main branch 16 and was rotated during the transition into this main branch so that the view now looks at the concave side of this drive blade. To ensure the correct angle of attack to the...

[0025] To restore the wind direction to the west, this drive blade is rotated 90° around the longitudinal axis of the main branch 16. In the case of the drive blade 10-g, this rotation has already occurred, so that the curved surface is again on the leeward side. Due to the inclined position of this main branch 16, a downward force is now generated, which is again supported by the Bemoulli effect.

[0026] It is understood that the 90° rotation of the drive blades around the longitudinal axis of the guideway can already occur during the transition from the connecting branch 18 to the descending branch 16. For illustrative purposes only, the drive blade 10-f is shown in its original angular position in Fig. 1. The drive blade 10-h is approaching the lower end of the main branch 16. The drive blade 10-i has already entered the lower connecting branch 18' and has been rotated so that it is located on the upper side of the connecting branch, facing the rear side of the drive blade. When the drive blade 10-i then traverses the 90° bend 36 (Fig. 3), it subsequently has the same orientation relative to the guideway as the drive blade 10-j, which is already approaching the ascending main branch 14.When entering the ascending branch, the drive blade is then rotated by 180° so that it is again on the leeward side of the guideway (like blade 10-a).

[0027] The rotation of the drive blades around the axis parallel to the direction of movement can be controlled, for example, by the path of the slot in the guideway 18, in which the holders 22 and 24 move. If the movement path 18 is formed by a tube with a polygonal cross-section, this rotation can also be controlled by twisting this polygonal tube. The holders 22, 24 can then roll with low friction on the outer surfaces of the polygonal tube, for example, using rollers. Optionally, a slotted tube with an integrated ball chain system with mounts for the blade profiles can also be used.

[0028] In the example shown, the angle of attack of the drive blades relative to the horizontal roughly corresponds to the inclination of the main branches 14 and 16. By selecting this angle of attack, or rather the inclination of the main branches, the performance of the wind turbine can be optimized. An angle of attack in the range of 60° - 80° has proven to be favorable. Another favorable operating range is angles of attack between 30° and 40°.

[0029] Another way to optimize performance is to regulate the deceleration force exerted by the driven machine on the blades depending on the wind speed. This allows the rotational speed of the drive blades to be adjusted, which, together with the wind speed, determines the angle of attack at which the air flows against the blades. This allows the angle of attack to be optimized with regard to the current wind speed.

[0030] Fig. 6 shows a view analogous to Fig. 4 of a guide track 12' according to another exemplary embodiment. Here, the guide track is mounted with its lower connecting branch 18' on a turntable 38, so that the entire guide track can be rotated about a vertical axis and thus optimally aligned with the wind direction. In the example shown, a mast 40 protrudes centrally from the turntable 38, to which a sail 42 is rigidly attached. Due to the wind pressure acting on the sail, the guide track 12' is then always aligned so that the ascending main branch 14 is inclined against the wind direction and the descending main branch 16 is inclined in the wind direction.

Claims

PATENT CLAIMS 1. Wind turbine with a number of wing-like drive blades (10-a to 10-j) which are guided in a circumferential direction on an endless guide track (12; 12') and which can be adjusted with respect to the wind direction (W) in such a way that they exert an aerodynamic propulsive force acting in a uniform direction of rotation on a power transmission element (20) which is in driving connection with a machine (28) to be driven, characterized in that the guide track (12; 12') has two main branches (14, 16) which can be adjusted in opposite directions obliquely to the wind direction (W), which are connected to one another at both ends via a respective connecting branch (18, 18'), and in that the drive blades are arranged at least on the main branches (14, 16) transversely to the guide track (12;12') and, depending on their current position on the guideway, are adjustable between two angular positions which are rotated relative to each other about an axis running in the direction of movement of the drive blades.; 2. Wind turbine according to claim 1, wherein the ascending main branch (14) and the descending main branch (16) of the guideway (12; 12') lie in mutually offset vertical planes.

3. Wind turbine according to claim 2, wherein the main branches (14, 16) are inclined at the same angle to the vertical.

4. Wind turbine according to one of the preceding claims, in which each drive blade (10-a to 10-j) is held on at least one holder (22, 24) which is guided on the guide track (12; 12'), and in which the guide track and the holders are designed such that they together control the rotation of the drive blades about the axis running in the direction of movement.

5. Wind turbine according to claim 4, wherein each drive blade has at least two holders (22, 24), one of which is arranged in the region of the leading edge and the other in the region of the trailing edge of the drive blade.

6. Wind turbine according to claim 4 or 5, in which the guideway (12; 12') is designed as a tube, in the interior of which the power transmission element (20) designed as an endless belt runs, and in which the holders (22, 24) extend through slots in the wall of the tubular guideway and are connected to the power transmission element (20).

7. Wind turbine according to one of the preceding claims, wherein the angle of attack of the drive blades (10-a to 10-j) relative to the horizontal is between 60° and 80° when the drive blades are located on one of the main branches.

8. Wind turbine according to one of claims 1-6, wherein the angle of attack of the drive blades (10-a to 10-j) relative to the horizontal is between 30° and 40° when the drive blades are located on one of the main branches.

9. Wind turbine according to one of the preceding claims, wherein the guide track (12') is mounted on a turntable (38) and is rotatable about a vertical axis.

10. Wind turbine according to claim 9, with a sail (42) for aligning the guideway (12') into the wind.

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