Hybrid vertical axis wind turbine

Abstract

Disclosed is a Hybrid Vertical Axis Wind Turbine. The present invention pertains to the field of renewable energy technologies, specifically focusing on wind power generation. More particularly, the invention relates to hybrid vertical-axis wind turbines that incorporates an active blade adjustment mechanism to optimize performance based on varying wind conditions. The blade adjustment mechanism is controlled by a control arm (30), which is linked to the blades (20) with a specific linkage arrangement (40, A, D, 32, 34, C, B, E, 36, 38, F). The invention uses both lift and drag type forces that combine to produce a large torque, allowing operation at lower rotation speeds than prior art solutions.

Description

[0001] Hybrid Vertical Axis Wind Turbine

[0002] FIELD OF THE INVENTION

[0003] The present invention pertains to the field of renewable energy technologies, specifically focusing on wind power generation. More particularly, the invention relates to hybrid vertical-axis wind turbines that incorporates an active blade adjustment mechanism to optimize performance based on varying wind conditions.

[0004] BACKGROUND OF THE INVENTION

[0005] Wind turbines which convert the kinetic energy of wind into electrical power are broadly categorized based on the orientation of their rotational axis: horizontal-axis wind turbines (HAWTs) and vertical-axis wind turbines (VAWTs). Furthermore, wind turbines can be classified based on the aerodynamic forces they harness: dragforce turbines and lift-force turbines. Lift-type turbines, including HAWTs, Darrieus- type, H-type VAWTs, use aerofoil shaped blades to generate lift, enabling them to achieve greater efficiency by converting lift into relatively high rotational motion and torque, particularly when their blades move rapidly relative to the wind.

[0006] Within the category of VAWTs, there are two primary types: lift-type turbines, such as H-rotors, helical rotors, and Darrieus turbines, and drag-type turbines, like the Savonius model.

[0007] VAWTs offer several key advantages over their horizontal counterparts. One of the most notable is their ability to capture wind from any direction without the need for a yaw mechanism, which is a common failure point in HAWTs. Additionally, VAWTs are particularly well-suited for residential areas, especially in regions where turbines are installed at lower elevations. In such environments, wind conditions tend to be more variable and less consistent, and VAWTs' ability to operate efficiently in turbulent, shifting winds makes them a more effective choice. However, VAWTs are not without challenges. The cyclic forces and centrifugal forces applied on the blades during operation create significant structural challenges, which can lead to reduced durability and a shorter operational lifespan for the turbine.

[0008] To enhance the low starting torque and efficiency of VAWTs, particularly under low wind conditions, variable pitch mechanisms have been developed. These mechanisms allow the turbine blades to adjust their angle relative to the wind, optimizing performance across different wind speeds and directions. Variable pitch systems can be broadly categorized into two types: active and passive. Active pitch control systems rely on predefined kinematic mechanisms to achieve specific blade angles depending on the rotor's azimuthal position. On the other hand, passive systems automatically adjust the blade angles using a vane, or based on aerodynamic and inertial forces without the need for external power or control inputs.

[0009] Various mechanical arrangements have been developed for control of blade angles.

[0010] One typical design uses a gear linkage system for pitch control. This mechanism uses an inner gear attached to the turbine's rotating shaft, complemented by three outer gears to facilitate the pitching motion of the blades. One example of this arrangement is known from the patent US8602719. A gear-based arrangement has the drawback that they tend to be noisy.

[0011] Patent application US20130017084 discloses a cam track arrangement which can provide any angle for the blades. Such an arrangement has certain drawbacks: they are noisy, sliding arrangements are prone to wear over time, and they are quite vulnerable to freezing conditions.

[0012] Patent US8410622 uses electrical blade actuators i.e. electric motors to turn each blade. While such an arrangement allows provision of completely adjustable angles at any point in the rotation, such an arrangement is quite complicated and expensive.

[0013] Another mechanism for adjusting blade angles is presented in the conference publication by C.M. Xisto et al, "Wind energy production using an optimized variable pitch vertical axis rotor", Proceedings of the ASME 2014 International Mechanical Engineering Congress and Exposition IMECE2014 November 14-20, 2014, Montreal, Quebec, Canada. This publication describes an arrangement, where the trailing edges of the blades are connected by a link to an off-axis crank. This arrangement makes the blades turn during rotation of the rotor, and the direction and amount of turn is controlled by the angle of the crank.

[0014] A similar approach is described by patent application US20190153998 which discloses a vertical axis wind turbine with moving blades. This patent application describes an arrangement where the length of the crank is controlled by an electrical motor, and the blades are connected to the crank by a linkage arrangement. While this arrangement provides certain freedoms in controlling the blade angles, the arrangement is quite heavy and complicated. In this arrangement, the motor and sliding mechanism rotate along with the turbine, introducing significant mechanical challenges. The rotation of these components with the rotor leads to severe imbalance issues, making it difficult to maintain the rotor's balance. Additionally, balancing such a mechanism further complicates the structure, increasing its complexity, cost and maintenance requirements. Furthermore, this complexity makes the system unsuitable for harsh climate conditions, where reliability and simplicity are important. This arrangement is a Darrieus-type turbine using lift forces, whereby must rotate at high speeds, even above 200 rotations per minute (RPM), to compensate for low torque and generate a meaningful amount of electricity. However, this fast rotation, combined with varying blade angles, induces significant vibrations and mechanical challenges, compromising the turbine's structural integrity and operational stability.

[0015] Despite continuous advancements in VAWTs, several challenges persist that limit their widespread adoption and efficiency. Variable pitch turbines, while offering improved performance, still face significant structural challenges due to the highspeed operation required to generate substantial electricity. The cyclic and centrifugal forces exerted on the blades during high speed rotation create considerable stress, leading to increased vibration and a shortened operational lifespan. Additionally, the current variable pitch designs often struggle to achieve the desired blade pitch angle relative to the azimuthal position of the rotor, resulting in limited efficiency.

[0016] Specifically, there is a need for a design that can: (I) maximize driving force in low- speed wind conditions, (II) minimize resistance forces, (III) adapt to harsh climate environments, and (IV) remain affordable to manufacture with a low levelized cost of energy (LCOE). The start-up performance of a turbine, which is heavily influenced by resistance forces, is another critical aspect that current designs have not fully addressed. Although variable pitch systems have made strides in improving start-up speeds, the existing solutions still rely on high-speed conditions to generate adequate electricity.

[0017] SUMMARY OF THE INVENTION

[0018] The problems of prior art are alleviated by using a rotor structure as described in the characterising part of claim 1 .

[0019] The invention provides a novel hybrid wind turbine. This hybrid design incorporates principles from two vertical wind turbines: a lift-type wind turbine and a Savonius drag-type wind turbine, combining the use of both drag and lift forces. By combining these two types, the configuration not only eliminates resistive forces on the negative wind side and generates additional drag forces on the positive wind side, but also generates positive lift force on the negative wind side. This results in a high torque, low-speed configuration that significantly reduces structural challenges and enhances the turbine's lifespan. This invention introduces a hybrid VAWT that effectively overcomes the inherent drawbacks of traditional VAWT designs, offering improved performance and durability, but also offers improved reliability and efficiency, particularly in variable and low wind conditions.

[0020] The present invention takes advantage of an innovative combination of a crank- rocker-coupler mechanism to integrate both lift and drag types of VAWTs, resulting in a hybrid design. This mechanism actively adjusts the pitch angle of the blades, thereby optimizing the angle of attack under varying wind conditions. This approach enables the VAWT to effectively combine the benefits of both drag- and lift-type turbines while addressing and overcoming the inherent drawbacks associated with each.

[0021] The inventive vertical-axis wind turbine introduces a simplified blade pitch control mechanism that eliminates the need for complex moving pairs such as gears, belts, cams, sliding, and timing components. This simplification enhances the adaptability of the turbine to harsh climate environments and contributes to its overall robustness.

[0022] BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Various embodiments of the invention will be described in detail below, by way of example only, with reference to the accompanying drawings, of which

[0024] Figure 1 illustrates schematically the inventive blade control mechanism according to an embodiment of the invention,

[0025] Figure 2 illustrates a top view of the blade control mechanism of one blade according to an embodiment of the invention,

[0026] Figure 3 shows a perspective view of the mechanism of figure 2,

[0027] Figure 4 shows an exploded view of the embodiment illustrated in figures 2 and 3,

[0028] Figure 5 shows the control mechanisms of eight blades according to an embodiment of the invention,

[0029] Figure 6 shows how the inventive blade control mechanism positions the blades relative to the wind in an embodiment of the invention, Figure 7 illustrates how the inventive blade control mechanism can adjust the blade angles in order to partially brake the rotation of the turbine rotor according to an embodiment of the invention,

[0030] Figure 8 illustrates how the inventive blade control mechanism can adjust the blade angles in order to strongly brake or even stop the rotation of the turbine rotor according to an embodiment of the invention,

[0031] Figure 9 illustrates an isometric view of a turbine with eight blades 20 according to an embodiment of the invention, and

[0032] Figure 10 illustrates a wind generation system according to an embodiment of the invention.

[0033] DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

[0034] The following embodiments are exemplary. Although the specification may refer to "an", "one", or "some" embodiment(s), this does not necessarily mean that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Features of different embodiments may be combined to provide further embodiments.

[0035] In the following, features of the invention will be described with a simple example of a blade angle control mechanism with which various embodiments of the invention may be implemented. Only elements relevant for illustrating the embodiments are described in detail. Details that are generally known to a person skilled in the art may not be specifically described herein.

[0036] Figure 1 illustrates schematically the inventive blade control mechanism according to an embodiment of the invention. Figure 1 shows the location A of the center of the rotation axis of the turbine, the arm 30 of a control crank, one blade 20, and various elements connecting the blade 20 and the arm 30 of the control crank. For clarity and ease of understanding the blade control mechanism, figure 1 only shows the mechanism controlling one blade 20.

[0037] The arm 30 of the control crank is arranged to be rotated by an axle that is in this embodiment located inside the central shaft of the turbine coaxially within the shaft such that the arm can be rotated independently of the turbine rotor using the control crank axle while the turbine rotor rotates around its own shaft.

[0038] As is known to a man skilled in the art, although having a central shaft or axle is common in various turbine structures, some turbine structures do not comprise a central shaft or axle. For example, a turbine can be connected to a bearing hub or a bearing arrangement that carries the weight of the rotating turbine while allowing the turbine to rotate and while transferring the rotating torque to a generator for generating electricity. In such a turbine structure, the control crank axle can be arranged in the middle of the bearing arrangement in order to allow turning of the control crank axle independent of the rotation of the turbine.

[0039] In addition to arm 30 and blade 20, figure 1 illustrates a first link 32, a rocker 34, a second link 36, and a second arm 38. The first link 32 connects point D at end of arm 30 and point C of rocker 34. Rocker 34 is rotatably connected to the body of the turbine rotor at point B. The second link 36 connects point E of the rocker 34 to point F of the second arm 38. The second arm 38 is connected in a fixed way to blade 20, so that any movement of arm 38 induced by link 36 turns the blade 20. Connections at points D, C, E and F allow rotational movement at that point. Point G indicates the rotational axis of the blade 20. When the arm 30 of the control crank moves, it moves point D, which in turn moves the first link 32, which in turn rotates the rocker 34 around point B. Rotational movement of rocker 34 moves point E and therefore the second link 36, which in turn rotates the second arm 38 which rotates the blade 20.

[0040] Since crank arm 30 does not rotate with the turbine rotor, the crank arm and the linkage mechanism causes each blade to go through a sequence of angles during one rotation of the turbine rotor. Examples of these sequences of angles are shown in figures 6, 7, and 8 which are discussed later in this specification. The position of the crank arm 30 therefore does not change the sequence itself, but it does determine the phase of the sequence i.e. at which point of the rotation each sequence angle does happen. This allows control of the turbine in varying wind directions and speeds.

[0041] Figure 2 illustrates a top view of the blade control mechanism of one blade according to an embodiment of the invention. For clarity, only one blade and the mechanism associated with that blade is shown in figure 2. Reference numbers and letters relate to the same elements as in Figure 1 .

[0042] Figure 2 shows a body part 22 of the turbine rotor, a blade 20, and a supporting arm 23. The supporting arm 23 is fixedly connected to the body part 22, and the blade 20 is rotatably connected to the other end of supporting arm 23 at point G.

[0043] Figure 2 shows the crank arm 30. The crank arm 30 is fixed at point A to the crank arm axle. The crank arm 30 is rotatably connected to the first link 32 at point D. The first link 32 is rotatably connected to the rocker 34, 34a, 34b at point C. The rocker 34, 34a, 34b is rotatably connected to body part 22 at point B. The rocker 34, 34a, 34b is rotatably connected to the second link 36 at point E. The second arm 36 is connected to the second arm 38 at point F. The second arm 36 is fixedly connected to blade 20 in order to rotate the blade.

[0044] In the example of figure 2, the rocker 34, 34a, 34b comprises two arms 34a and 34b which are fixedly connected to each other so that when the first link 32 pushes the rocker at point C, the rocker pushes the second link 36 at point E. This arrangement of two arms fixed to each other is only a possible example of a mechanical structure for the rocker. In the example of an embodiment illustrated in figure 2 this structure is merely a result of mechanical design allowing implementation of control mechanisms for eight blades in a single turbine rotor.

[0045] Exact dimensions of these elements depend on requirements of any particular implementation and the environment such an implementation is designed for. For example, an optimal size of the turbine rotor and number as well as size of blades depend on wind conditions and environmental conditions at the installation site, as well as output power requirements. A man skilled in the art can optimise these dimensions and details in order to provide a turbine suitable for requirements of a particular application of the invention. Consequently, these dimensions and details are not discussed in any further detail in this specification.

[0046] Figure 2 illustrates that in this embodiment, the rotation axis G of the turbine blade 20 coincides with the middle plane 20a of the blade. However, in other embodiments of the invention, the rotation axis G may be offset from the middle plane 20a of the blade 20.

[0047] Figure 2 illustrates that in this embodiment, the rotation axis G of the turbine blade is located roughly in the middle of the blade. However, in other embodiments of the invention, the rotation axis G may be located at other points such as in the front of the leading edge, behind the trailing edge, or at any point inbetween. In other words, the rotation axis G may be offset from the middle of the blade and / or the middle plane 20a of the blade.

[0048] Figure 3 shows an isometric view of the mechanism of figure 2, illustrating the control mechanism of a single blade 20.

[0049] Figure 3 shows a body part 22 of the turbine rotor, a blade 20, and a supporting arm 23. The supporting arm 23 is fixedly connected to the body part 22, and the blade 20 is rotatably connected to the other end of supporting arm 23.

[0050] Figure 3 shows the crank arm 30. The crank arm 30 is fixed to the crank arm axle. The crank arm 30 is rotatably connected to the first link 32. The first link 32 is rotatably connected to the rocker 34. The rocker 34 is rotatably connected to body part 22. The rocker 34 is rotatably connected to the second link 36. The second arm 36 is connected to the second arm for rotating the blade 20. Due to the perspective view of figure 3, the second arm 38 is not readily visible in figure 3.

[0051] Figure 4 shows an exploded view of the embodiment illustrated in figures 2 and 3. Figure 4 shows a body part 22 of the turbine rotor, and supporting structure 19A of the whole turbine arrangement as well as a mast 19B to which the turbine has been installed. For clarity, the entire supporting arm 36, the second arm 38 and the blade 20 are not illustrated in figure 4.

[0052] Figure 4 shows the crank arm 30. The crank arm 30 is fixed to the crank arm axle 40. The crank arm 30 is rotatably connected to the first link 32. The first link 32 is rotatably connected to the rocker 34, 34a, 34b. The rocker 34, 34a, 34b is rotatably connected to the second link 36.

[0053] Figure 4 illustrates a part of the crank control mechanism which is not readily visible in figures 2 and 3. Figure 4 illustrates the crank axle 40, as well as an electric motor 42 and a gear arrangement 43. The electric motor 42 and the gear arrangement 43 are arranged to rotate the crank axle 40 and crank arm 30. The electric motor 42 and the gear arrangement 43 are fixed to the supporting structure 19A,19B so that the crank axle and arm can be rotated independent of the rotation of the whole turbine rotor arrangement. For clarity, the shaft of the turbine rotor as well as the generator and any gear arrangements for generating electricity are not illustrated in figure 4.

[0054] Figure 5 shows the control mechanisms of eight blades according to an embodiment of the invention. As figure 5 illustrates, the mechanism can become quite complex when there are many blades in the rotor. This is the reason why figures 1 to 4 illustrate the mechanism of only one blade.

[0055] Figure 5 illustrates a body part 22 of the turbine rotor. The crank arm 30 is barely visible under a number of first links 32. However, connection point D at end of the crank arm, to which all first links 32 are rotatably connected, is shown in figure 5. Each of the first links 32 is rotatably connected to a rocker 34a, 34b, each of which is rotatably connected to a second link 36. For clarity, not all of the first links 32, rockers 34a, 34b and second links 36 are denoted by a reference number in figure 5.

[0056] Despite the appearance of complexity in figure 5, the mechanism controlling movement of each blade is quite simple in construction. Figure 6 shows how the inventive blade control mechanism positions the blades relative to the wind in an embodiment of the invention.

[0057] Figure 6 illustrates the top view of the blade angles at an optimal position. For clarity, figure 6 illustrates two blades 20 and their control mechanisms.

[0058] Figure 6 illustrates how the inventive blade control mechanism adjusts the angle of the blades so that the turbine takes advantage of both lift and drag type driving forces simultaneously.

[0059] In this specification, we use the term positive torque to denote torque rotating the turbine in the desired rotation direction i.e. power producing direction, and the term negative torque for any torque opposing that direction.

[0060] In figure 6, the wind comes from the left side as indicated by the arrows 100, and the turbine rotor rotates in the anticlockwise direction. The blade 20 on the top in figure 6 travels against the wind, and generates a lift-type driving force producing a positive torque at least part of the way while travelling against the wind. The blade 20 on the bottom in figure 6 travels in the direction of the wind, generating a dragtype driving force producing a positive torque at least part of the way while travelling in the direction of the wind. These driving forces combine to produce torque rotating the turbine, i.e. each blade generates positive torque from both drag and lift forces during a single revolution of the turbine. In other words, the inventive turbine comprises a mechanism arranged to control the blade angles to cause each blade to generate a drag force producing positive torque at least a part of the way while travelling in the direction of the wind and a lift force producing positive torque at least a part of the way while travelling against the wind.

[0061] Taking advantage of both lift and drag type driving forces increases the rotational regions where each blade produces a positive torque driving the turbine rotor, and allows the inventive turbine construction to provide a high enough torque for starting in very low winds, and a high torque to produce energy at much lower rotational speeds than prior art turbines. Figure 7 illustrates how the inventive blade control mechanism can adjust the blade angles in order to partially brake the rotation of the turbine rotor in an embodiment of the invention. Braking of the rotor may be necessary in high winds.

[0062] In figure 7, the wind comes from the left side as indicated by the arrows 100, and the turbine rotor rotates in the anticlockwise direction. The blade 20 on top in figure 7 travels against the wind, but is now at such an angle that it provides little or no lifttype driving force, and is close to start generating a drag type force opposing the rotation. The blade 20 on bottom of figure 7 travels in the direction of the wind, generating drag-type force. In the example of figure 7, the blades in combination still produce a driving torque, but less than in the example of figure 6. Figure 7 thus illustrates a control crank position suitable for high winds, where limiting the rotation speed of the rotor is desirable.

[0063] Figure 8 illustrates how the inventive blade control mechanism can adjust the blade angles in order to strongly brake or even stop the rotation of the turbine rotor according to an embodiment of the invention. Braking or even stopping the rotor may be necessary in very high winds e.g. in a storm in order to avoid damaging the turbine due to overspeeding.

[0064] In figure 8, the wind comes from the left side as indicated by the arrows 100, and the turbine rotor rotates in the anticlockwise direction.

[0065] The blade 20 on top in figure 8 travels against the wind, but is now at such an angle that it generates a drag type force opposing the rotation. The blade 20 on bottom of figure 8 travels in the direction of the wind but is aligned in the wind direction, generating a very small drag force driving the rotation. In combination these two blades produce a force that strongly brakes and may even stop the rotation of the turbine rotor. Figure 8 thus illustrates a control crank position suitable for storm conditions, where strong braking or even stopping the rotor is desirable to avoid damage due to overspeeding. Figures 6, 7 and 8 illustrate how the rotation of the turbine rotor is controlled by adjusting the angle of the control crank arm 30 relative to the wind direction. The inventive mechanism creates certain profile of blade angles which each blade goes through during each rotation of the turbine rotor, which is illustrated by the blade positions in figures 6, 7 and 8. The direction of the control crank arm 30 determines how these angles meet the wind, and whether the blades in combination generate a maximal or optimal rotating torque, a non-optimal or partially braked torque, or a strongly limited or zero rotating torque.

[0066] Figure 9 illustrates an isometric view of a turbine with eight blades 20 according to an embodiment of the invention. Figure 9 illustrates for clarity a complete turbine rotor. Most of the mechanism for controlling blade angles as described previously in this specification is located below a cover 101 . This cover protects the mechanism from weather, avoiding any problems with water or freezing conditions. Figure 9 also illustrates such an embodiment of the invention in which the turbine rotor comprises a central rotor 120. In the example of figure 9, the central rotor comprises four fixed blades. Such an embodiment has various advantages. Such a central rotor may provide a small torque to increase the torque output of the turbine rotor. Further, such a central rotor 120 may also at least partially block the wind from blades in position opposite to the wind direction, and thereby reduce drag forces caused by blades at that position.

[0067] In an embodiment of the invention the control crank and the control crank arm 30 are controlled by a wind vane. In such an embodiment a wind vane is mechanically linked to the control crank axle to keep the control crank axle at an optimal position in any wind direction.

[0068] Figure 10 illustrates a wind generation system according to an embodiment of the invention. In this embodiment, the control crank is driven by an electric motor, which in turn is controlled by a control unit. The control unit is connected to at least one wind sensor for determining the wind direction and speed. Figure 10 illustrates a turbine rotor 10 with a plurality of blades 20. The rotor comprises a blade angle control mechanism 11. The blade angle control mechanism 11 can be for example a mechanism according to any of the previous figures.

[0069] Figure 10 also illustrates the turbine shaft 124 rotated by the turbine rotor. A gear mechanism 120 is connected to the shaft 124, and a generator 122 is connected to the gear mechanism for producing electric power from the rotational energy produced by the turbine rotor. Figure 10 further illustrates the control crank axle 40, which is driven by an electric motor 42 and a gear arrangement 43. The motor 42 is controlled by a control unit 130. The control unit is arranged to receive measurement results from at least one wind sensor 132, and control the position of the control crank based at least in part on the measurement results.

[0070] In this embodiment, the control unit is arranged to rotate the control crank to an optimal position at low wind speeds, and gradually to a more and more non-optimal position if wind increases above a predefined normal operating range. The control unit is arranged to move the control crank to a fully braking or completely stopping position, if the wind increases above a predefined storm limit. In this embodiment, the control unit is arranged to maintain the control crank at the desired position relative to wind direction if the wind direction varies, while the wind speed determines whether that position should be an optimal, braking or a stopping position.

[0071] In a further embodiment of the invention, said control unit 130 is arranged to maintain the control crank arm at a predefined first angle relative to the wind direction, when wind speed is below a first predetermined limit. In this embodiment, this first predetermined limit is the upper wind speed limit for normal i.e. optimal operation.

[0072] In a further embodiment of the invention said control unit 130 is arranged to maintain the control crank arm at a predetermined second angle relative to the wind direction, when wind speed is between said first predetermined limit and a second predetermined limit. In this embodiment, this first predetermined limit is the upper wind speed limit for normal i.e. optimal operation, this second predetermined limit is the wind speed limit for storm conditions, and this predetermined second angle corresponds to a partially braking position of the crank arm 30.

[0073] In a further embodiment of the invention said control unit 130 is arranged to maintain the control crank arm at a predetermined third angle relative to the wind direction, when wind speed is above said second predetermined limit. In this embodiment this second predetermined limit is the wind speed limit for storm conditions, and this predetermined third angle corresponds to a maximally braking position of the crank arm 30.

[0074] In various embodiments of the invention, the control unit 130 may be implemented using a computing device comprising one or more processors and a memory unit comprising executable program code causing said one or more processors to perform the actions described in the previous paragraphs. A man skilled in the art knows many different ways to implement a control unit using a computing device, whereby the invention is not limited to any specific arrangement of a control unit.

[0075] CERTAIN BENEFITS OF THE INVENTION

[0076] The invention has several advantages.

[0077] The inventive blade control mechanism is simple and therefore economical to produce. The inventive blade control mechanism is also light in weight compared to many prior art solutions, which reduces mechanical forces experienced by the whole arrangement.

[0078] Further, the inventive blade control mechanism allows hybrid operation i.e. taking advantage of both lift and drag type forces from startup to full speed operation. The hybrid operating principle maximises torque created by the wind, which allows the inventive turbine to be self-starting. Further, the high torque produced by the inventive turbine allows operation of the turbine at much lower rotational speeds than prior art solutions. This is a considerable benefit, as higher rotational speeds naturally require a sturdier construction as the forces acting on the turbine structure are higher in high rotational speeds. Consequently, the inventive turbine structure can be built with thinner and lighter materials than prior art solutions, reducing construction costs. Lighter weight also reduces the required strength of the support structures of the turbine, reducing cost even further. Lower rotational speeds and rotational forces also reduce wear and tear on the turbine, increasing the lifetime of the inventive turbine structure. This is a great benefit for construction of blades, as lower rotational speeds require slower changes in the angles, reducing rotational accelerations and forces experienced by the blades. This further increases the lifetime of the blades and their control mechanisms.

[0079] Low rotational speeds also reduce noise created by the blades of the turbine in the wind as well as the blade angle control mechanism. The inventive blade control mechanism is also very quiet in itself, as there are only rotating links between the elements adjusting the blade angles without need of belts or gears.

[0080] Low rotational speeds also cause less vibrations, therefore causing less vibrational noise and decreasing the risk of metal fatigue in various components of the mechanism.

[0081] The simple structure of the inventive blade control mechanism greatly enhances tolerance of harsh climate environments, ensuring optimal functionality even in the most challenging weather conditions.

[0082] The inventive blade angle control mechanism allows easy and accurate control of the turbine in varying wind conditions simply by rotating the control crank. This arrangement allows maintaining the blade angles at optimal positions for startup and operation within a normal wind speed operating range, while allows gradual braking and even stopping at high wind or storm conditions. This simple control allows the turbine to swiftly adjust the blade pitch angle in response to sudden changes in wind direction, thereby maximizing energy capture and efficiency. This design improves the start-up speed of vertical-axis wind turbines, enabling them to initiate power generation more rapidly and enhancing overall power output under average wind speeds.

[0083] Overall, the invention represents a substantial advancement in VAWT technology, offering enhanced performance, durability, and adaptability in a wide range of operating environments.

[0084] CERTAIN FURTHER OBSERVATIONS

[0085] In view of the foregoing description it will be evident to a person skilled in the art that various modifications may be made within the scope of the invention. While a preferred embodiment of the invention has been described in detail, it should be apparent that many modifications and variations thereto are possible, all of which fall within the true spirit and scope of the invention.

[0086] It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

[0087] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment.

[0088] As used herein, a plurality of items, structural elements, compositional elements, and / or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present invention may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention.

[0089] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the previous description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

[0090] While the foregoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.

Claims

CLAIMS1 . A vertical axis wind turbine, having a rotor body (22) and a plurality of blades (20) rotatably connected to the rotor body, characterised in that the turbine comprises at least a mechanism arranged to control the blade angles to cause each blade to generate positive torque from both drag and lift forces during a single revolution of the turbine, said mechanism comprising a control crank arm (30) connected to a control crank axle (40) at a first end (A) of said control crank arm, each blade being linked to the second end (D) of said control crank arm (30) with a mechanism comprising a first link (32) having a first end and a second end, said first end being rotatably connected to said second end (D) of said control crank arm (30), a rocker (34) having a first connection point (C) and a second connection point (B), whereby said second end of said first link (32) is rotatably connected to said first connection point (C) of said rocker, and said second connection point (B) of said rocker (34) is rotatably connected to the rotor body (22), said rocker (34) further comprising a third connection point (E), a second link (36) having a first end and a second end, whereby said first end of said second link (36) is rotatably connected to said third connection point (E) of said rocker (34), a second arm (38) fixedly connected to the blade (20), said second arm (38) having a connection point (F), whereby said second end of said second link (36) is rotatably connected to said connection point (F) of said second arm (38).

2. A vertical axis wind turbine according to claim 1, characterised in that the rotation axis (G) of each turbine blade is offset from the middle of the blade (20).

3. A vertical axis wind turbine according to claim 1, characterised in that it further comprises a central rotor (120) having fixed blades.

4. A vertical axis wind turbine according to claim 1, characterised in that it further comprises a wind vane mechanically connected to said control crank axle (40) for controlling the blade angles on the basis of wind direction.

5. A vertical axis wind turbine system, characterised in that it comprises at least a vertical axis wind turbine according to claim 1, an electric motor (42) for rotating the control crank axle (40), a wind direction sensor (132), a wind speed sensor (132), and a control unit (130) arranged to receive measurement results from said wind sensor and to control the rotation angle of the control crank arm (30) at least in part based on the wind direction and wind speed.

6. A vertical axis wind turbine system according to claim 5, characterised in that said control unit (130) is arranged to maintain the control crank arm at a predefined first angle relative to the wind direction, when wind speed is below a first predetermined limit.

7. A vertical axis wind turbine system according to claim 6, characterised in that said control unit (130) is arranged to maintain the control crank arm at a predetermined second angle relative to the wind direction, when wind speed is between said first predetermined limit and a second predetermined limit.

8. A vertical axis wind turbine system according to claim 7, characterised in that said control unit (130) is arranged to maintain the control crank arm at a predetermined third angle relative to the wind direction, when wind speed is above said second predetermined limit.

Images