Slow-running wind turbine rotor

Abstract

Wind turbine rotor 1 with a vertical axis of rotation 2 and at least 3 rotor arms 3 arranged offset by 120 degrees, on which rotor blades 4 are pivotably mounted about a range limited by first and second stops 6, 7 via a blade axis 5 running parallel to the rotor axis 2, wherein the rotor blades 4 have an aerodynamic profile and, when exposed to wind on the side 8 facing away from the direction of rotation, so-called downwind run 12, are oriented essentially parallel to the associated rotor arms 3 and bear against the stop 6 and, when exposed to wind on the front side 9, so-called upwind run 13, assume a position in which their air resistance is reduced to a minimum, characterized in thatthat the aerodynamic profile of the rotor blades 4 is formed from a curved leading edge 9 and a substantially flat trailing edge 8, and that the blade axis 5 is arranged off-center with respect to the cross-section of the blade profile, specifically in the radially outer third of the blade profile, and that the first stop 6 on the rotor arm 3 is arranged at its radially outer end and limits the pivoting of the rotor blade 4 during downwind operation 12 to a position parallel to the rotor arm 3, while the second stop 7 on the rotor blade 4 is arranged between the blade axis 5 and the stop 6 such that, during headwind operation 13, it limits the inward pivoting of the rotor blade 4 with its leading edge 9 to approximately 90 degrees with respect to the rotor arm 3, and that each rotor arm 3 is arranged offset in a different plane in the vertical direction so that mutual shading of the rotor blades 4 is largely excluded.

Description

[0001] The invention relates to a slow-running wind turbine rotor with a vertical axis of rotation and adjustable rotor blades

[0002] A large number of such wind turbine rotors are known from the prior art, as shown and described, for example, in the documents DE 27 18 608 A1, DE 100 44 147 A1, US 2004 0057830 A1, US 2012 0301297 A1, WO 2009 086648 A2 and DE 3108 945 C2.

[0003] US 6,688,842 B2 discloses a wind turbine rotor with a vertical axis of rotation, the blades 14 of which are symmetrically designed like airfoils, and in which the lift forces on both sides cancel each other out. The pivoting range is limited by first and second stops 18, 19, which are arranged in such a way that the blades 14 assume a flow-obstructing position ( Fig. 4 and Fig. 6) take.

[0004] In the rotor known from DE 10 2008 003 003 A1, the rotor blades 2 have an aerodynamic profile which favours a system in the pressure wind position, but they are pivoted by up to 180 degrees during rotation and, in addition, must be held in a most favourable position or released from this position by a control device 4.

[0005] From DE 20 2019 002 224 U1, an H-Darrieus double rotor is known, the rotor arms of which are telescopic against spring tension and are arranged in one plane and which has a spring-loaded blade adjustment mechanism.

[0006] From US 2016 / 022943 A1 a wind turbine is known whose rotor has a circular frame 12 ( Fig. 1), which connects rotor arms 18, to the ends of which sail-like rotor surfaces 26 are pivotally attached, held by cords 32. According to Fig. 4 and Fig. 5, instead of rigid rotor arms, telescopic sections 74 AD can be provided, which are connected to a frame 114 divided into movable sections 68 AH.

[0007] A windmill with rigid, vertically offset curved rotor surfaces is known from US 300 932S.

[0008] US Pat. No. 2,038,467 discloses a windmill whose rotor blades 14 are limited in their pivoting range by stops 20, 21. Both stops are part of lower and upper plates 12, 15 in which the rotor blades 14 are mounted and are located radially inward (20) and outward (21) with respect to the pivot axes 16 of the rotor blades 14. The rotor blades 14 do not have an aerodynamically effective shape.

[0009] The wind turbine rotor known from US 7 258 527 B2 is comparable to that according to DE 82 28 078 U1, wherein the stop 522 limiting the pressure wind position is designed as an elastic elongated elevation on the rotor arm 52, while the second stop 54 has an evasive and resettable safety function against over-rotation of a rotor blade in the opposite direction beyond the stop 522.

[0010] The wind turbine rotor according to US 2012 / 0207601 A1 has freely pivoting rotor blades with an aerodynamically effective profile attached to the ends of rotor arms 21. The rotor blades 22 have a pivoting range of 180° between the pressure wind phase and the headwind phase.

[0011] In the wind turbine rotor according to DE 82 28 078 U1, the end faces of a cylindrical body, designed as discs 2, 3, assume the function of the rotor arms according to the application, with both the stops for pressure wind travel 23 to 26 and the stops for headwind travel being arranged on these discs 2, 3. The aerodynamic profile is designed such that, when airflow strikes the end face, it does not generate lift but rather offers the lowest possible drag. The pivoting range limited by the stops 31 to 34 is significantly more than 90 degrees, which results in a correspondingly larger return travel.

[0012] The wind turbine rotor known from EP 1205 661 A1 has aerodynamically shaped blades designed solely to reduce air resistance. Furthermore, in the pressurized position, they are limited by a single stop, formed as a web 16 between the upper and lower rotor arms 10, 12, which represents a fluidic obstacle. The pivoting range is greater than 90°, and a second stop is not provided.

[0013] The wind turbine rotor known from US 6 779 966 B2 does have a lift-enabling profile of the rotor blades 110, which are limited in their pivotability by a stop 160 when traveling in a pressure wind, but which must pivot by 180 when transitioning to traveling in a headwind in order to finally return to the radially inward position on the rotor arm 130.

[0014] The invention is therefore based on the object of providing a slow-running, wind direction-independent wind turbine rotor which has a high degree of efficiency with a small pivoting range of the rotor blades, low wear and low noise, and can be manufactured using technically simple means.

[0015] This object is achieved by a wind turbine rotor having the features of claim 1.

[0016] The wind turbine rotor according to the invention is suitable for effectively utilising even low airflow speeds because its blade profiles support the rotational movement through their airfoil effect. As a result, the blades come into contact with the rotor arm at the latest when a rotor arm is aligned parallel to the wind direction. On the face of a clock, this would be at 6 and 12 o'clock. If you look at an individual rotor blade, the lift force decreases from the 6 o'clock position and the wind pressure acting on the back of the blade profile increases, so-called pressure wind travel, and decreases again from around 9 o'clock, with the proportion of lift force gradually increasing again. In the 12 o'clock position, the blade profile is at its maximum lift speed and from then on begins to avoid the wind pressure acting on it by pivoting its front side inwards. In the headwind range, its air resistance is at its lowest.

[0017] The wing-like shape of the rotor blades and their pivoting range, which is limited by stops, not only enables a reduction in air resistance when flying against the wind, but also leads to a contact with the rotor arm as the angle between the rotor blade and the rotor arm becomes more acute, in which the lift force supports the rotational movement of the rotor.

[0018] The small swivel range of the rotor blades of approximately 90 degrees and the relatively slow rotation speed of the rotor have a positive effect on wear and noise.

[0019] Telescopically adjustable rotor arms allow for self-regulation, i.e., a change in the rotor speed to adapt to the wind speed. The length change can occur as the speed increases, either against the action of a force accumulator, such as tension springs, or arbitrarily via adjusting devices.

[0020] The wind turbine rotor according to the invention can be constructed using relatively simple technical means. For example, the blade profile can be made from the wall of a cylindrical tube, container, or the like, cut lengthwise to one-third the diameter.

[0021] To achieve optimal utilization of the wind force acting on the blade profiles, the rotor arms are arranged at different levels, thus preventing leeward blade profiles from being shaded by windward ones. Impairment of the lift effect of blade profiles located in the 12 o'clock area due to slipstream or turbulence from the rotor axis or hub can be counteracted by a slim or open design.

[0022] The hub of the wind turbine rotor can consist of a type of cylindrical cage, which is rotatably mounted on bearings readily available from the automotive industry. The wind turbine rotor rods, like the rotor arms, can be braced with wire to prevent warping. Telescoping square tubes can be used for the rotor arms.

[0023] It is a matter of craftsmanship to also make the rotor hub closed in order to avoid wind noise caused by wires and rods.

[0024] A wind turbine rotor manufactured in this way is particularly interesting for areas with weak infrastructure, such as developing countries. Small wind turbines constructed according to the invention can provide significant utility value there, either for generating electrical energy or directly driving water pumps, for example. Their efficient design makes them attractive for use on ships and in the maritime sector in general. Fig. 1 Top view of a three-armed rotor with length-adjustable rotor arms Fig. 2 Top view of a rotor blade and side view Fig. 3 Eight-armed rotor with phase-dependent position of the rotor blades Fig. 4 Side view of a three-arm wind turbine rotor with vertically offset rotor arms

[0025] The wind turbine rotor according to the invention is described below using the Fig. 1 to 4 described.

[0026] In Fig. 1 shows a plan view of a right-turning three-armed wind turbine rotor 1, the rotor blades 4 of which are in Fig. 1 in the 12 o'clock position in upwind travel 11, in the 4 o'clock position in downwind travel 13 and in the 8 o'clock position in pressure travel 12.

[0027] In Fig. 2 shows a rotor blade 4 in cross-section and in a view of its rear side 8. The rotor blade 4 has an airfoil-like profile with a substantially flat rear side 8 and a curved front side 9. The rotor blade 4 is pivotally mounted on a rotor arm 3 by means of a blade axis 5. In an orientation parallel to the rotor arm 3, the pivoting of the rotor blade 4 is limited by a first stop 6, which is part of the rotor arm 3 and is attached to its radially outer end. The pivoting of the rotor blade 4 away from this orientation is limited by a second stop 7 attached to the rotor blade 4 at an angle of approximately 90 degrees to the rotor arm 3. The front side 9 then points in the direction of the rotor axis 2. Due to the arrangement of the blade axis and stops 6, 7, the movement of the rotor blade 4 is similar to that of a seesaw.

[0028] In Fig. 3 illustrates the changing positions of the rotor blades using the example of an 8-arm wind turbine rotor 1. In the 12 and 6 o'clock positions, the lift travel area 11, the inner or outer end faces 10 of the rotor blades 4 are blown by the wind, causing the rotor blades 4 to align parallel to the rotor arms 3 and their further pivoting to be limited by the first stops 6. With further clockwise rotation, the wind pressure on the front side 9 of the rotor blades 4 increases, causing the rotor blades to transition to the headwind travel position 13, thus offering the lowest possible air resistance at approximately 3 o'clock. From there, the lift effect gradually sets in, reaching a maximum again as the lift travel 11 at the 6 o'clock position, which transitions into the pressure travel 12, which has its maximum at 9 o'clock.

[0029] The forces causing rotational movement on the rotor arms 3 are thus composed of lift forces and pressure forces of varying strength, which are counteracted by air resistance, primarily in the area between approximately 1 and 2 o'clock.

[0030] In Fig. Figure 4 shows a three-arm wind turbine rotor 1 with vertically offset rotor arms 3. This design has the advantage of avoiding shading of the leading rotor arm 3, resulting in better utilization of the wind power. For the reasons mentioned above, the rotor axis 2 is designed as an open cage. The Fig. 1 and Fig. 3 The rotor axes 2 shown in plan view only reflect the principle but in practical implementation must be designed in such a way that they do not have any flow-hindering effect on the rotor blades 4. List of reference symbols 1 wind turbine rotor 2 Rotor axis or hub 3 Rotor arm 4 rotor blades 5 wing axis 6 first attack 7 second attack 8 Back of 4 9 Front of 4 10 front side of 4 11 Buoyancy ride 12 printing runs 13 Headwind riding

Claims

[1] Wind turbine rotor 1 with a vertical axis of rotation 2 and at least 3 rotor arms 3 arranged offset by 120 degrees, on which rotor blades 4 are pivotably mounted about a blade axis 5 running parallel to the rotor axis 2 about a range limited by first and second stops 6, 7, wherein the rotor blades 4 have an aerodynamic profile and, when exposed to wind on the rear side 8 in the direction of rotation, so-called pressure travel 12, are aligned substantially parallel to the associated rotor arms 3 and rest against the stop 6 and, when exposed to wind on the front side 9, so-called headwind travel 13, assume a position in which their air resistance is reduced to a minimum, characterized bythat the aerodynamic profile of the rotor blades 4 is formed from a curved front side 9 and a substantially flat rear side 8 and the blade axis 5 is arranged off-center with respect to the cross-section of the blade profile, specifically in the radially outer third of the blade profile, and that the first stop 6 is arranged on the rotor arm 3 at its radially outer end and limits the pivoting of the rotor blade 4 during pressure travel 12 to a position parallel to the rotor arm 3, while the second stop 7 is arranged on the rotor blade 4 between the blade axis 5 and the stop 6 in such a way that it limits pivoting of the rotor blade 4 with its front side 9 inwards to approximately 90 degrees with respect to the rotor arm 3 when traveling against a headwind 13, and that each rotor arm 3 is arranged in a different plane offset in the vertical direction in such a way that mutual shading of the rotor blades 4 is largely excluded. [2] Wind turbine rotor according to claim 1 characterized by that the rotor arms 3 are designed to be telescopically adjustable in length in order to enable a change in the speed of the rotor to adapt to the wind speed as a self-regulation. [3] Wind turbine rotor according to claim 2 characterized by that in the length-adjustable rotor arms 3 energy accumulators, preferably tension springs, are provided, which counteract the centrifugal force that increases with increasing speed. [4] Wind turbine rotor according to claim 2 characterized by that the change in length of the rotor arms is achieved by randomly acting adjusting means.

Images