Over-speed braking apparatus for vertical axis wind turbine

Abstract

Provided is an over-speed braking apparatus for a vertical axis wind turbine. The over-speed braking apparatus comprises: a fan, having multiple blades; and an over-speed spoiler control unit, disposed in the blades and having an over-speed spoiler. When a rotation speed of the fan is greater than a rated rotation speed, the over-speed spoiler partially extends beyond the blades, and when the rotation speed of the fan is less than the rated rotation speed, the over-speed spoiler automatically retracts into the blades. By means of the design of providing an over-speed spoiler control unit in blades of a wind turbine, the over-speed spoiler control unit can automatically regulate and reduce the rotational speed of the wind turbine at a high wind speed, such that a vertical axis wind turbine can continuously output a power generation capacity close to a rated power generation capacity at high wind speeds, so as to realize a large increase in the effective power generation capacity of the vertical axis wind turbine.

Description

Overspeed braking device for vertical axis wind turbine Technical Field

[0001] This invention relates to vertical axis wind turbines (VAWT), and more particularly to an overspeed braking device for a vertical axis wind turbine. Background Technology

[0002] The blade yaw or pitch control design of horizontal axis wind turbines (HAWT) has proven highly successful in commercial operation over the past 20 years. This design has significantly increased the power generation of HAWT turbines. However, vertical axis wind turbines (VAWT) operate differently from HAWT turbines. VAWT turbines cannot employ the adjustable blade angle control functionality of HAWT turbines to control blade speed. Therefore, VAWT turbines remain at the stage of traditional additional unloading or braking shutdown to protect the turbine system. Many VAWT turbine patents claim to use similar blade pitch control design concepts to achieve high wind speed power generation, but all these designs have proven to be failures, mainly due to excessively weak mechanical strength or overly complex control systems.

[0003] Currently, large horizontal axis wind turbines employ blade control mechanisms with overspeed control, as shown in Figure 1A, achieved through yaw or pitch control, with pitch control technology achieving optimal performance. Its basic mechanism is shown in Figure 1B. This involves adjusting the windward angle of the wind turbine blades 101 to optimize power generation at high wind speeds. All wind turbines 100 should operate at their optimal power generation efficiency during rated power generation. When the wind speed continues to increase, causing the wind turbine 100's rotational speed to reach a pre-set limit, the blade pitch control mechanism 102 will activate, adjusting the windward angle of the blades 101 to an angle with lower aerodynamic efficiency. If the wind speed continues to increase, the blade pitch control mechanism 102 will further adjust the windward angle of the blade 101 to a worse aerodynamic angle. This situation continues until the wind speed reaches about 25 m / s, at which point the windward angle of the blade 101 is perpendicular to the wind direction at 90 degrees. At this point, the aerodynamic efficiency of the blade 101 is zero, and the wind turbine 100 stops operating.

[0004] In theory, the overspeed blade pitch control mechanism of the horizontal axis wind turbine 200 can operate effectively mainly due to two characteristics of its operation: (1) When the horizontal axis is running, all its blades 201 are aligned with the same wind direction at the same angle, as shown in Figure 2A. This eliminates the complexity of adjusting the different angles of attack for each blade 201 individually. (2) The horizontal axis wind turbine 200 maintains a constant angle of attack with the wind during operation. Therefore, there is no need to constantly change the angle of attack while the wind turbine is running. Therefore, the horizontal axis wind turbine 200 is well-suited for overspeed blade pitch control technology.

[0005] Conversely, the operating characteristics of the vertical axis wind turbine 300 are quite different from those of the horizontal axis wind turbine 200. The vertical axis wind turbine 300 encounters the following problems when using blade pitch control: (1) At the same time, the windward angles of all vertical axis blades 301A, 301B, and 301C facing the wind are completely different, as shown in Figure 2B. Therefore, in order to maintain a fixed and identical windward angle at the same time, each blade 301A, 301B, and 301C must have an independent windward angle control system. (2) When the vertical axis wind turbine 300 is running, as the wind turbine rotates, the individual windward angles of blades 301A, 301B, and 301C facing the wind are different at the same instant. Therefore, the three blades 301A, 301B, and 301C must be controlled separately. When a wind turbine completes one revolution, the angles of blades 301A, 301B, and 301C also change by exactly 360 degrees. This means that the angles of blades 301A, 301B, and 301C must be controlled at every moment of rotation. Therefore, if the blade pitch control technology of the horizontal axis wind turbine 200 is applied to the vertical axis wind turbine 300, each blade 301A, 301B, and 301C of the wind turbine needs to be controlled separately, and the angles need to be changed in a timely manner at every point in time. At high wind speeds, the rotational speed makes instantaneous angle changes even more difficult. Therefore, the operating characteristics of the vertical axis wind turbine 300 are clearly unsuitable for using blade pitch control.

[0006] Summary of the Invention

[0007] To address the challenge of high-wind-speed power generation in vertical-axis wind turbines, this invention provides an overspeed braking device for vertical-axis wind turbines, aiming to achieve automatic and self-controlled blade speed adjustment so as to enable continuous power generation of the wind turbine at high wind speeds.

[0008] The present invention provides an overspeed braking device for a vertical axis wind turbine that can solve the above-mentioned problems.

[0009] To achieve the aforementioned objective, the present invention provides an overspeed braking device for a vertical axis wind turbine, comprising: a wind turbine having multiple blades; and an overspeed turbulence control unit disposed within the blades and having an overspeed turbulence baffle. When the wind turbine's rotational speed is greater than its rated rotational speed, the overspeed turbulence baffle will partially extend beyond the blades, and when the wind turbine's rotational speed is less than its rated rotational speed, the overspeed turbulence baffle will automatically retract into the blades.

[0010] The advantages of this invention are as follows: By incorporating an overspeed turbulence control unit within the wind turbine blades, this unit can automatically adjust and reduce the wind turbine's rotational speed at high wind speeds. This allows the vertical axis wind turbine to continuously output power close to its rated capacity at high wind speeds, extending the effective operating wind speed of the vertical axis wind turbine and significantly increasing its effective power generation. Specifically, when the wind turbine's rotational speed exceeds its rated speed, the overspeed turbulence deflector partially extends beyond the blade, creating a drag-type negative force. The higher the wind speed and the faster the wind turbine's rotational speed, the greater the height the overspeed turbulence deflector extends due to centrifugal force, resulting in a greater negative force. This effectively regulates the rotational speed and power generation of the vertical axis wind turbine. When the wind turbine's rotational speed is below its rated speed, the overspeed turbulence deflector automatically retracts into the blade and no longer extends beyond the blade surface, thus restoring the blade's original streamlined shape and ensuring optimal power generation efficiency below the rated speed.

[0011] Preferably, the overspeed spoiler extends from the surface of the blades using the centrifugal force of the fan during rotation.

[0012] Preferably, the extent to which the overspeed spoiler extends from the blade surface is proportional to the fan speed.

[0013] Preferably, the overspeed spoiler control unit further comprises a base plate, two lever arms, a spring preload seat, and two spring assemblies; the base plate is fixed inside the blade; each of the two lever arms has a first pivot portion pivotally mounted on the base plate and a second pivot portion pivotally mounted on the overspeed spoiler opposite to the first pivot portion; the spring preload seat is fixed on the base plate and has a spring preload portion; the two spring assemblies are respectively disposed between the two lever arms and the spring preload portion of the spring preload seat; therefore, when the fan speed is greater than the rated speed, the centrifugal force generated by the overspeed spoiler is greater than the preload force of the spring assemblies, causing the overspeed spoiler to partially extend outside the blade; when the fan speed is less than the rated speed, the centrifugal force generated by the overspeed spoiler is less than the preload force of the spring assemblies, and the overspeed spoiler will automatically retract into the blade.

[0014] Preferably, after the first pivot of each lever arm pivots, the end of the first pivot moves linearly a first distance toward the base plate, and the second pivot moves linearly a second distance away from the base plate, the second distance being at least twice the first distance.

[0015] Preferably, each of the spring groups has a first spring and a second spring with different elastic coefficients; the first spring has a first spring portion provided on the lever arm and a second spring portion provided on the spring preload portion; the second spring has a third spring portion provided on the lever arm and a fourth spring portion provided on the spring preload portion.

[0016] Preferably, the first spring and the second spring are compression springs.

[0017] Preferably, it also includes a variable resistor and a wind power controller. The variable resistor is fixed on the base plate and has a resistance value sensing part connected to the overspeed spoiler. The resistance value is measured by the distance of linear displacement of the resistance value sensing part driven by the overspeed spoiler. The wind power controller is communicatively connected to the variable resistor to receive the resistance value and record and analyze it.

[0018] Preferably, the fan includes a vertically arranged rotating shaft, a plurality of arm assemblies disposed on the rotating shaft, and a plurality of blades disposed on the arm assemblies.

[0019] Preferably, the blade of the wind turbine is a lift-type blade. Attached Figure Description

[0020] Figure 1A is a perspective view showing a horizontal axis wind turbine with a yaw axis or blade variable blade control mechanism.

[0021] Figure 1B is a schematic diagram showing the operating state of the blade pitch control mechanism of a horizontal axis wind turbine.

[0022] Figure 2A is a schematic diagram showing the relationship between wind direction and the windward angle of the horizontal axis wind turbine blades.

[0023] Figure 2B is a schematic diagram showing the relationship between wind direction and the windward angle of the vertical axis wind turbine blades.

[0024] Figure 3 is a perspective view showing the state of the overspeed turbulence control unit installed inside the blades of the wind turbine.

[0025] Figure 4 is a schematic diagram showing the cross-sectional state of the overspeed turbulence control unit.

[0026] Figure 5A is a three-dimensional cross-sectional view showing the extended state of the overspeed spoiler.

[0027] Figure 5B is a schematic diagram showing the gas flow state when the overspeed spoiler is extended.

[0028] Figure 5C is a three-dimensional cross-sectional view showing the retracted state of the overspeed spoiler.

[0029] Figure 5D is a schematic diagram showing the gas flow state when the overspeed spoiler retracts.

[0030] Figure 6 is a schematic diagram showing the principle of lever arm operation of the overspeed turbulence control unit.

[0031] Figure 7 is a schematic diagram showing the dimensional relationship between the lever arm and the two spring groups at the starting point.

[0032] Figure 8 is a schematic diagram showing the dimensional relationship between the lever arm and the overspeed spoiler at the starting point.

[0033] Figure 9 is a schematic diagram showing the dimensional relationship between the lever arm and the two spring groups when the lever arm moves to its maximum extension point.

[0034] Figure 10 is a schematic diagram showing the dimensional relationship between the lever arm and the overspeed spoiler when the lever arm moves to its maximum extension point.

[0035] Figure 11 is a schematic diagram showing the state with a variable resistor and a wind power controller.

[0036] Figure 12 is a graph showing the state of increased power generation during the operation of the present invention.

[0037] Figure 13 is a schematic diagram showing the state of the overspeed spoiler on the slide rail. Detailed Implementation

[0038] Referring to Figures 3 to 5D, the overspeed braking device for a vertical axis wind turbine provided in this embodiment of the invention mainly consists of a wind turbine 1 and an overspeed turbulence control unit 400, wherein:

[0039] The fan 1 has multiple blades 2. In this embodiment, the fan 1 includes a vertically arranged rotating shaft 3, multiple support arm assemblies 4 disposed on the rotating shaft 3, and three blades 2 disposed on the support arm assemblies 4. Each blade 2 has an accommodating space 21, and the blade 2 is a lift-type blade, such as a Darius blade, but not limited thereto. Since the fan 1 is an existing component, and its operation method is the same as existing components, and is not the focus of this invention, the detailed structure and operation method of the component will not be described in detail.

[0040] The overspeed turbulence control unit 400 is located within the accommodating space 21 of the blade 2 and in region 5 as shown in Figure 3. The overspeed turbulence control unit 400 includes an overspeed turbulence plate 6, a base plate 9, two lever arms 8a and 8b, a spring preload seat 11, and two spring groups 10.

[0041] The overspeed spoiler 6 extends partially beyond the blade 2 when the fan 1's rotational speed is greater than its rated speed, and automatically retracts into the blade 2 when the fan 1's rotational speed is less than its rated speed. In this embodiment, referring to Figure 13, the overspeed spoiler 6 is mounted on a linear sliding rail 14, which slides on a slider 15 fixed to the base plate 9. The rail 14 provides a smooth and precise linear movement. The overspeed spoiler 6 extends from the surface of the blade 2 using the centrifugal force of the fan 1's rotation and slides along the guide rail to contact the airflow. The degree to which the overspeed spoiler 6 extends from the surface of the blade 2 is proportional to the fan 1's rotational speed. It is worth mentioning that the upper edge of the overspeed spoiler 6 is designed with a dust cover 61 to reduce the impact of the environment on the overspeed spoiler control unit 400, that is, to prevent dust and rainwater in the outside environment from entering the blade 2, so as to ensure the long-term stability of the overspeed spoiler control unit 400.

[0042] The base plate 9 is bolted to the surface of the blade 2 receiving space 21. The strong bolts ensure that the invention remains stable under the huge centrifugal force generated during high-speed rotation.

[0043] The lever arms 8A and 8B each have a first pivot portion 81A and 81B pivotally mounted on the base plate 9 and adjacent to each other, and a second pivot portion 82A and 82B pivotally mounted on the overspeed spoiler 6 opposite to the first pivot portion 81A and 81B. In this embodiment, the first pivot portion 81A and 81B are pivotally mounted on the base plate 9 using a self-lubricating bearing 71A and 71B, and the ends 83A and 83B of the first pivot portion 81A and 81B are rounded so that each lever arm 8A and 8B can easily pivot around the first pivot portion 81A and 81B without interfering with other components. The second pivot portion 82A and 82B are also pivotally mounted on the overspeed spoiler 6 using the self-lubricating bearing 72A and 72B.

[0044] The spring preload seat 11 has two spring preload sides 11A that are fixed to the base plate 9 by hexagonal bolts, and a spring preload part 11B that connects the two spring preload sides 11A. The spring preload part 11B corresponds to the two lever arms 8A and 8B and can form a specific distance with the two lever arms 8A and 8B.

[0045] The two spring groups 10 are respectively disposed between the two lever arms 8A and 8B and the spring preload portion 11B of the spring preload seat 11; in this embodiment, each spring group 10 has a first spring 10A and a second spring 10B with different elastic coefficients, and both the first spring 10A and the second spring 10B are compression springs, but the number and shape are not limited thereto; the first spring 10A has a first spring portion 101A fixed to the lever arms 8A and 8B and adjacent to the first pivot portions 81A and 81B, and a second spring portion 102A opposite to the first spring portion 101A and fixed to the spring preload portion 11B; the second spring 10B has a third spring portion 101B fixed to the lever arms 8A, 8B and adjacent to the second pivot portions 82A, 82B, and a fourth spring portion 102B opposite to the third spring portion 101B and fixed to the spring preload portion 11B; therefore, when the speed of the fan 1 is greater than the rated speed, the centrifugal force generated by the overspeed spoiler 6 is greater than the preload force of the spring assembly 10, causing the overspeed spoiler 6 to partially extend beyond the blade 2. When the speed of the fan 1 is less than the rated speed, the centrifugal force generated by the overspeed spoiler 6 is less than the preload force of the spring assembly 10, and the overspeed spoiler 6 will automatically retract into the blade 2.

[0046] It is worth noting that the first spring 10A and the second spring 10B included in each spring assembly 10 are selected with different elastic coefficient characteristics. They are cleverly designed through calculation to achieve the purpose of spring deflection, so as to cooperate with the action of the lever arms 8A and 8B being pushed out of the overspeed spoiler 6 by centrifugal force. At the same time, the spring preload seat 11 preloads the load force of each spring assembly 10 according to the pre-calculated centrifugal force of the fan 1 at the rated speed, so that the load force is equal to the centrifugal force of the fan 1 at the rated speed.

[0047] The above describes the configuration of the main components in the embodiments of the present invention. The operation and effects of the present invention are explained below.

[0048] Referring to Figures 4 to 5B, when the speed of the fan 1 exceeds the rated speed, the centrifugal force generated by the total mass of the overspeed spoiler 6 and related connecting components exceeds the load force originally designed to be preloaded in the spring assembly 10. Therefore, the overspeed spoiler 6 pulls the second pivots 82A and 82B of each lever arm 8A and 8B, and the self-lubricating bearings 72A and 72B thereon, causing displacement. This, in turn, pulls the two lever arms 8A and 8B, and each lever arm 8A and 8B then moves towards the first pivot 81A. The pivoting motion (or warping offset) is generated by the self-lubricating bearings 71A and 71B as fulcrums, causing uneven force on each spring assembly 10 and resulting in the skewed movement of each lever arm 8A and 8B. This pushes the overspeed spoiler 6 out of the blade 2. The overspeed spoiler 6 extends precisely out of the surface of the blade 2 along the guide rail on the base plate 9. The extended part of the overspeed spoiler 6 forms a drag-type aerodynamic effect on the surface of the blade 2, which is the opposite force to the original lift-type positive force effect of the blade 2, resulting in significant braking deceleration and reduced power generation efficiency.

[0049] Referring to Figures 4, 5C, and 5D, when the speed of the fan 1 drops below the rated speed, the centrifugal force of the overspeed spoiler 6 decreases accordingly. Since the present invention has pre-compressed the load force of each spring assembly 10 to be equal to the centrifugal force of the fan 1 at the rated speed, when the generated centrifugal force is less than the pre-compression force of the spring assembly 10, the spring assembly 10 will automatically return to its original state and extend, thereby driving each lever arm 8A and 8B to pivot in the opposite direction and pull the overspeed spoiler 6 back to its original starting point, so that the blade 2 returns to a streamlined blade surface with good aerodynamic efficiency.

[0050] Therefore, by incorporating an overspeed turbulence control unit 400 within the blades 2 of the wind turbine 1, this control unit 400 can automatically adjust and reduce the rotational speed of the wind turbine 1 at high wind speeds. This allows the vertical axis wind turbine to continuously output power close to its rated capacity at high wind speeds, thereby extending the effective operating wind speed of the vertical axis wind turbine and significantly increasing its effective power generation. In other words, when the wind turbine 1's rotational speed exceeds its rated speed, the overspeed turbulence deflector 6 will partially extend beyond the blades 2, thus preventing damage to the original lift-type blades. In addition to improving aerodynamic efficiency, it also creates a drag-type negative force. As the wind speed increases and the turbine 1 rotates faster, the overspeed spoiler 6 extends to a greater height as the centrifugal force increases, resulting in a greater negative force that disrupts aerodynamic lift efficiency. This effectively controls the rotational speed and power generation of the vertical axis wind turbine. When the turbine 1 rotates below its rated speed, the overspeed spoiler 6 automatically retracts into the blade 2 and no longer extends beyond the surface of the blade 2, thus restoring the original streamlined shape of the blade 2 and ensuring that the turbine 1 has the best power generation efficiency below its rated speed.

[0051] It is worth noting that each spring assembly 10 selects appropriate spring characteristics to determine its installation position and ensure that each component can cooperate with each other. This process is very important because when the centrifugal force of the overspeed spoiler 6 exceeds the preset load of the first spring 10A and the second spring 10B, the two lever arms 8A and 8B need to pivot around the first pivots 81A and 81B (i.e., the self-lubricating bearings 71A and 71B) as pivot points. This design allows the second pivots 82A and 82B of each lever arm 8A and 8B to have a displacement distance several times that of the first pivots 81A and 81B. As shown in Figures 4 and 6, after the first pivots 81A and 81B (i.e., self-lubricating bearings 71A and 71B) of each lever arm 8A and 8B pivot, the ends 83A and 83B of the first pivots 81A and 81B are linearly displaced a first distance in the direction of the base plate 9, and the second pivots 82A and 82B are linearly displaced a second distance in the direction away from the base plate 9. The second distance is five times the first distance, but is not limited to this.

[0052] The primary function of each spring assembly 10 is to withstand the centrifugal force generated by the overspeed spoiler 6 when the fan 1 reaches the rated speed required by the design, and to fix the overspeed spoiler 6 at the origin. Therefore, when the fan 1's speed is below the rated speed, the total centrifugal force of the overspeed spoiler 6 and its related components is lower than the preload value originally designed for the spring assembly 10, and each spring assembly 10 remains stationary. When the fan 1's speed exceeds the rated speed, the total centrifugal force of the overspeed spoiler 6 and its related components is higher than the preload value originally designed for the spring assembly 10, and each spring assembly 10 begins to be compressed and displaced. That is, the overspeed spoiler 6 will pull the two lever arms 8A and 8B, and cause the two lever arms 8A and 8B to be at the first pivot 8. 1A and 81B (i.e., self-lubricating bearings 71A and 71B) act as pivot points to generate pivoting linkage. When the lever arms 8A and 8B pivot, they will simultaneously compress the first spring 10A and the second spring 10B. The first spring 10A is closer to the first pivot 81A, so it is compressed and displaced less. The second spring 10B is relatively farther from the first pivot 81A, so it is compressed and displaced more. Therefore, in the design of each spring group 10, the first spring 10A must have stronger resistance than the second spring 10B, so that the total extension distance of the overspeed spoiler 6 will be related to the characteristics of the first spring 10A and the second spring 10B, the total length of the two lever arms 8A and 8B, and the thickness of the blade 2.

[0053] Referring to Figure 6, the invention utilizes the unique mechanical advantages of lever arm 8B. The second pivot 82B of lever arm 8B is pivotally mounted on the overspeed spoiler 6 using a self-lubricating bearing 72B. The end of the first pivot 81B at the other end of lever arm 8B is rounded, allowing the end 83B of the first pivot 81B to move freely. Simultaneously, the ratio of the distance between the first pivot 81B and the second pivot 82B to the distance between the ends 83A and 83B and the first pivot 81B is 5:1. Therefore, when the end 83B of the first pivot 81B of lever arm 8B pivots downwards by 1mm, the overspeed spoiler 6 is pushed out by 5mm, producing a 5 (outer):1 (inner) multiple extension effect, thus fully utilizing the limited internal space of the blade 2.

[0054] Referring to Figure 7, which shows how the present invention selects a type of spring with suitable characteristics to achieve the following as defined in the present invention: when the fan 1 reaches its rated speed, when one end of each lever arm 8a and 8B displaces by 1 mm, the overspeed spoiler 6 displaces by 5 mm; when the fan 1 rotates faster, the overspeed spoiler 6 extends proportionally; conversely, when the fan 1 rotates slower, each spring group 10 pulls the overspeed spoiler 6 back to its original position proportionally by a multiple of its original value, and it no longer extends.

[0055] It is worth noting that the design of each spring assembly 10 in this invention is cleverly coordinated with the lever arms 8A and 8B to achieve the function of tilting outwards by a multiple (e.g., 5 times) around the first pivot points 81A and 81B as the fulcrum center when the lever arms 8A and 8B are subjected to force. Therefore, the elastic coefficient (K10A) of the first spring 10A selected in this invention must be larger than that of the second spring 10B. This is because when the springs are subjected to force and displacement occurs, the first spring 10A experiences a smaller displacement and a significantly smaller force than the second spring 10B. The selection of the first spring 10A and the second spring 10B is explained in the following steps.

[0056] Step 1: When each lever arm 8A and 8B is at the origin, determine the preload of the total spring.

[0057] As shown in Figure 7, the first step in the design is to determine the preload applied to the lever arms 8A and 8B by the first spring 10A and the second spring 10B. This preload must be equal to the centrifugal force generated by the total mass of the overspeed spoiler 6 and its related connections when the fan 1 reaches its rated speed. This state is referred to as the design starting point of the lever arms 8A and 8B. As shown in Figure 7, the total length of the first spring 10A and the second spring 10B before preloading is X. After preloading, the lengths of the first spring 10A and the second spring 10B are X1 and X2, respectively. The lengths of the first spring 10A and the second spring 10B after preloading are based on the total height inside the Darrieus blade 2. Therefore: the compression length of the first spring 10A = (X - X1); the compression length of the second spring 10B = (X - X2).

[0058] As shown in Figure 8, the second step in the design is to calculate the preload force of the springs when the lever arms 8A and 8B are at the starting point. This preload force can be calculated by multiplying the compression length of the first spring 10A and the second spring 10B in the spring assembly by the spring constant (K) of each spring.

[0059] The load force of the first spring 10A is F10A=-K*(X-X1);

[0060] The load force of the second spring 10B is F10B=-K*(X-X2);

[0061] Next, the torque required for each lever arm 8A and 8B to move from its starting point is calculated. Since the starting point of each lever arm 8A and 8B is subjected to a load force by the first spring 10A and the second spring 10B, the torque required for each lever arm 8A and 8B to move can be calculated by overcoming the load force preloaded by the first spring 10A and the second spring 10B, and thus the distances LA and LB to the lever fulcrum (i.e., the first pivots 81A and 81B) can be calculated.

[0062] Torque, τ=(F 10A *LA)+(F 10B *LB)

[0063] When the fan 1 rotates beyond its rated speed, the centrifugal force generated by the overspeed spoiler 6 causes the lever arms 8A and 8B to begin displaced from their starting point and warp along the lever fulcrum (i.e., the first pivots 81A and 81B). Since there are two sets of lever arms 8A and 8B, the lever torque is twice the rated torque. The total length of the lever arms is (L), and the total spring force is:

[0064] (Total spring force), F T =2*τ / L

[0065] Step 2: When lever arms 8A and 8B reach their maximum extension points, the total force on the springs can be calculated based on the respective spring groups 10.

[0066] First, it is necessary to determine the total deformation length of the first spring 10A and the second spring 10B when the lever arms 8A and 8B reach their maximum extension, as shown in Figure 9. This is the additional compression length of the first spring 10A and the second spring 10B when the lever arms 8A and 8B are initially pre-compressed on the lever arms 8A and 8B and reach their maximum extension point. The maximum extension of the lever arms 8A and 8B can then be used to calculate the additional compression lengths Z1 and Z2 of the first spring 10A and the second spring 10B after pre-compression using trigonometric functions. The total compression lengths X'1 and X'2 of the first spring 10A and the second spring 10B can be calculated from the additional compression length of the springs and the initial pre-compression lengths X1 and X2, respectively. When the lever arms 8A and 8B reach their maximum extension:

[0067] For the first spring 10A, the total compression length is X'1 = X1 - Z1

[0068] For the second spring 10B, the total compression length is X'2 = X2 - Z2

[0069] The total deformation of the first spring 10A and the second spring 10B can be obtained by subtracting the preload deformation X'1 and X'2 from the actual deformation X: Deformation of the first spring 10A = (X - X'1); Deformation of the second spring 10B = (X - X'2);

[0070] The next step is to calculate the resistance generated by the first spring 10A and the second spring 10B when the lever arms 8A and 8B reach their maximum extension, as shown in Figure 10. The resistance of each spring can be calculated by multiplying the total deformation length of the spring by the spring's deformation constant (K).

[0071] The resistance of the first spring 10A is F10A=-K*(X–X'1);

[0072] The resistance of the second spring 10B is F10B=-K*(X–X'2);

[0073] The next step is to calculate the torque when lever arms 8A and 8B reach their maximum extension point. At this point, the resistance of the first spring 10A and the second spring 10B acting on lever arms 8A and 8B during the initial preload must be considered. When lever arms 8A and 8B reach their maximum extension point, relative to the lever fulcrum (i.e., the first pivots 81A and 81B), denoted as LA and LB, the total torque of lever arms 8A and 8B is:

[0074] Torque,τ=(F 10A *LA)+(F 10B *LB);

[0075] When the speed of the fan 1 exceeds the rated speed, the overspeed spoiler 6 will cause the lever arms 8A and 8B to warp due to the centrifugal force, resulting in a multiple extension distance; the originally pre-compressed first spring 10A and second spring 10B are therefore compressed; the total force required for each lever arm 8A and 8B to reach its maximum extension point can be calculated by multiplying the torque of a lever by two and then dividing by the length of the lever (L).

[0076] Total spring force: F T =2*τ / L

[0077] Step 3; Determine the fan speeds of the overspeed spoiler 6 at the start-up extension point and the maximum extension point:

[0078] Centrifugal force is the main factor determining the maximum extension point of lever arms 8A and 8B. The calculation formula used is F = m * ω^2 * R, where F represents the sum of all spring forces in the spring assembly 10, m represents the sum of the mass of the overspeed spoiler 6 including the linked parts (including lever arms 8A, 8B, etc.), ω is the angular velocity of the fan 1, and R is the radius of the blades 2 of the fan 1. Using this formula, the rotational speed of the fan 1 at the maximum extension point of lever arms 8A and 8B can be calculated; because this point is the cut-out stopping speed set by the fan 1. Since the overspeed spoiler 6 connects lever arms 8A and 8B, when lever arms 8A and 8B are warped by force, the overspeed spoiler 6 extends its blades 2 outward into the gas dynamic field.

[0079] In another embodiment, the present invention utilizes a variable resistor 12 and a signal line connected along the blade to a wind energy controller 13 to track the height of the overspeed brake baffle 6 extending beyond the blade 2. Referring to Figure 11, the variable resistor 12 is fixed on the base plate 9 and has a resistance value sensing unit 121 connected to the overspeed baffle 6. The resistance value is measured by the linear displacement of the resistance value sensing unit 121 caused by the overspeed baffle 6. The wind energy controller 13 is communicatively connected to the variable resistor 12 to receive, record, and analyze the resistance value. When the overspeed baffle 6 extends, the resistance value sensing unit 121 of the variable resistor 12 is simultaneously pulled, thus causing a change in the resistance ohm value. This change in resistance ohm value can be transmitted digitally to the wind energy controller 13 for interpretation via a sensor using wired or wireless means. The wind energy controller 13 can generally be remotely monitored using a commonly used computer or communication network.

[0080] Table 1 below shows the relationship between the variable resistor 12 selected in this invention and the sensor, which converts the distance the overspeed spoiler 6 moves linearly into an ohmic resistance value.

[0081] Table 1

[0082] The present invention also employs a variable resistor 12 containing a sensor to wirelessly transmit data, and uses a wireless transmitter to wirelessly transmit the extension distance of the overspeed spoiler 6 to the wind energy controller 13. This device design allows the dynamic displacement of the overspeed spoiler 6 in the blade 2 to be interpreted and monitored in real time in the static wind energy controller 13, and further realizes the function of remote monitoring via computer or communication network through the system of the wind energy controller 13.

[0083] Figure 12 shows the increased power generation effect during the operation of this invention. To discuss the efficiency of the wind turbine, it is essential to understand the relationship between the turbine's rotational speed, energy conversion efficiency, and wind speed. Increased wind speed directly causes changes in both turbine rotational speed and power generation efficiency. Initially, at low wind speeds, the turbine rotates slowly because there is insufficient force to drive the blades; therefore, the power generation efficiency constant (representing the constant for converting wind energy into electrical energy) is also low.

[0084] During low rotational speeds, the overspeed spoiler 6 remains in the closed position, thus preserving the original shape of the blade surface and maintaining optimal streamlined profile for the best aerodynamic efficiency. When the wind speed reaches the rated wind speed, both the rotational speed and power generation efficiency of the wind turbine reach their optimal values.

[0085] When the wind speed continues to increase beyond the rated wind speed, the fan speed will exceed the rated speed. When the fan speed exceeds the rated speed, the overspeed spoiler of this invention will start to extend its blades, thus disrupting the original streamlined shape of the blades and causing a decrease in aerodynamic efficiency. In addition, it also induces drag-type aerodynamic effects, causing the fan speed to decrease. The overspeed spoiler of this invention extends, thus reducing the fan speed and power generation when the wind speed exceeds the rated wind speed, preventing it from exceeding the design limits of the fan (design limits for speed and power generation), allowing the fan to generate electricity normally. As wind speed increases, resulting in higher turbine rotation speed, the overspeed spoiler of this invention extends further due to the increased centrifugal force caused by the increased rotation speed. This has a greater effect on reducing the turbine's rotation speed and power generation efficiency, while still maintaining the turbine's designed rotation speed and power generation limits. Therefore, the turbine can continue to generate electricity until the wind speed reaches extremely high levels. At this point, the overspeed spoiler of this invention has extended to its maximum value (limited by the limited space inside the Darrieus blades). However, when the reduced rotation speed and power generation exceed the turbine's designed limits, the turbine must be shut down. In this case, Figure 12 shows the operating range for power generation (A) without the overspeed spoiler of this invention and the increased operating range for power generation (B) with the overspeed spoiler of this invention. As shown in Figure 12, the area of ​​the operating range for power generation (B) with the overspeed spoiler of this invention is almost equal to the area with (A). Therefore, in high wind speed environments, the annual power generation of a turbine equipped with the overspeed spoiler of this invention will be more than double that of a turbine without the overspeed spoiler.

[0086] As can be clearly seen from the above detailed description of the invention, the overspeed spoiler of the present invention extends from the blade surface at high wind speeds to disrupt its aerodynamic efficiency, thereby reducing the rotational speed and power generation, and maintaining continuous power generation at high wind speeds. This method allows the wind turbine to regulate its rotational speed and power generation within the permissible operating range through a function similar to pneumatic braking, thus maintaining power generation. It is well known that the aerodynamic efficiency of blades is very sensitive to the streamline shape of the blade surface; even slight changes in the blade streamline shape can lead to significant changes in the aerodynamic effect. Therefore, the overspeed spoiler of the present invention effectively solves the obstacle of continuous power generation at high wind speeds in vertical axis Darrieus blade wind turbines. Furthermore, when the wind turbine's power generation capacity reaches 100kW or more, the internal space of the Darrieus blade will enable the overspeed spoiler of this invention to perform even greater functions. When the Darrieus blade space is large enough, the height of the overspeed spoiler extending beyond the Darrieus blade will be sufficient to completely destroy the aerodynamic efficiency of the Darrieus blade to zero. Therefore, the wind turbine will automatically shut down and generate zero power, without the need for external braking to cut out. This demonstrates the significant contribution of the overspeed spoiler device of this invention to vertical shaft wind turbines.

[0087] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0088] List of reference numerals

[0089] 100…wind turbine blades 101…

[0090] 102… Blade variable pitch control mechanism 200… Horizontal axis wind turbine

[0091] 201…blade 300…vertical axis wind turbine

[0092] 301…blade 400…overspeed turbulence control unit

[0093] 1…fan 2…blades

[0094] 21…accommodating space 3…rotation axis

[0095] 4… outrigger assembly 5… area

[0096] 6…overspeed spoiler 61…dust cover

[0097] 71A, 71B, 72A, 72B… Self-lubricating bearings

[0098] 8A, 8B… Lever arms 81A, 81B… First pivot

[0099] 82A, 82B… Second pivot 83A, 83B… End

[0100] 9…base plate 10…spring assembly

[0101] 10A…First spring 101A…First pivot

[0102] 102A…Second pivot 10B…Second spring

[0103] 101B…First Pivot 102B…Second Pivot

[0104] 11…Spring preload seat 11A…Spring preload side

[0105] 11B…Spring preload section 12…Variable resistor

[0106] 121…Resistance sensing unit 13…Wind power controller

[0107] 14… Slide rail 15… Slider.

Claims

1. An overspeed braking device for a vertical axis wind turbine, characterized in that, Include: A wind turbine having at least one blade; and An overspeed turbulence control unit is located inside the blade and has an overspeed turbulence baffle. When the fan speed is greater than the rated speed, the overspeed turbulence baffle will extend partially outside the blade. When the fan speed is less than the rated speed, the overspeed turbulence baffle will automatically retract into the blade.

2. The overspeed braking device for a vertical axis wind turbine according to claim 1, characterized in that, The overspeed spoiler extends from the surface of the blades using the centrifugal force generated when the fan is rotating.

3. The overspeed braking device for a vertical axis wind turbine according to claim 2, characterized in that, The extent to which the overspeed spoiler extends from the blade surface is proportional to the rotational speed of the fan.

4. The overspeed braking device for a vertical axis wind turbine according to claim 1, characterized in that, The overspeed turbulence control unit also includes a base plate, two lever arms, a spring preload seat, and two spring assemblies. The base plate is fixed inside the blade. Each of the two lever arms has a first pivot portion pivotally mounted on the base plate and a second pivot portion pivotally mounted on the overspeed turbulence plate opposite to the first pivot portion. The spring preload seat is fixed on the base plate and has a spring preload portion. The two spring assemblies are respectively disposed between the two lever arms and the spring preload portion of the spring preload seat. Therefore, when the fan speed is greater than the rated speed, the centrifugal force generated by the overspeed turbulence plate is greater than the preload force of the spring assemblies, causing the overspeed turbulence plate to partially extend outside the blade. When the fan speed is less than the rated speed, the centrifugal force generated by the overspeed turbulence plate is less than the preload force of the spring assemblies, and the overspeed turbulence plate will automatically retract into the blade.

5. The overspeed braking device for a vertical axis wind turbine according to claim 4, characterized in that, After the first pivot of each lever arm pivots, the end of the first pivot moves linearly a first distance toward the base plate, and the second pivot moves linearly a second distance away from the base plate, the second distance being at least twice the first distance.

6. The overspeed braking device for a vertical axis wind turbine according to claim 4, characterized in that, Each of the spring groups has a first spring and a second spring with different elastic coefficients; the first spring has a first spring portion disposed on the lever arm and near the first pivot, and a second spring portion disposed on the spring preload portion; the second spring has a third spring portion disposed on the lever arm and near the second pivot, and a fourth spring portion disposed on the spring preload portion.

7. The overspeed braking device for a vertical axis wind turbine according to claim 6, characterized in that, The first spring and the second spring are compression springs, and the elastic coefficient of the first spring is greater than that of the second spring.

8. The overspeed braking device for a vertical axis wind turbine according to claim 4, characterized in that, It also includes a variable resistor and a wind power controller. The variable resistor is fixed on the base plate and has a resistance value sensing part connected to the overspeed spoiler. The resistance value is measured by the distance of linear displacement of the resistance value sensing part driven by the overspeed spoiler. The wind power controller is communicatively connected to the variable resistor to receive the resistance value and record and analyze it.

9. The overspeed braking device for a vertical axis wind turbine according to claim 1, characterized in that, The fan includes a vertically arranged rotating shaft, multiple arm assemblies on the rotating shaft, and multiple blades on the arm assemblies.

10. The overspeed braking device for a vertical axis wind turbine according to claim 1, characterized in that, The blade of the wind turbine is a lift-type blade.

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