JPH0118269B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a propeller-type wind turbine with a wind direction plate that automatically changes propeller pitch according to wind speed fluctuations.

In recent years, wind turbines have been reconsidered from the standpoint of energy conservation, and various types of wind turbines are being built, but propeller-type wind turbines are the mainstream because of their simple structure and high efficiency.

This propeller-type wind turbine has a pitch angle at which efficiency is best depending on the circumferential speed ratio, and this best pitch angle changes depending on the circumferential speed ratio. Therefore, for propeller-type wind turbines, a variable pitch type that controls the pitch angle of the blades by the circumferential speed ratio is preferable, but for small wind turbines, it is generally preferable to use a fixed pitch type to avoid a complicated pitch control mechanism. is common, and in that case, the actual situation is that it is used in a low efficiency state when the wind speed is other than the design standard wind speed. On the other hand, large wind turbines are usually equipped with a pitch control mechanism due to the effectiveness of their use.Pitch control mechanisms can be roughly divided into those that use a mechanical speed control mechanism that uses centrifugal force, etc., and those that use a mechanical speed control mechanism that uses centrifugal force etc. There is an electronically controlled type that detects the pitch angle and changes the pitch angle using a servo mechanism. However, the former has a complex structure and the inertia of the entire wind turbine is high, making it difficult to match the speed governing mechanism with the wind turbine's rotation speed, which can lead to uneven rotation or even excessive rotation, leading to accidents. The drawback is that there are not many examples. Furthermore, the latter method requires various sensing elements, computers, etc., and therefore has the drawback of being expensive.

The present invention was made in order to improve the above-mentioned current situation, and an object of the present invention is to provide a propeller-type wind turbine with a wind direction plate that can control the pitch angle based on aerodynamic principles or automatically provide the best pitch angle. do.

According to the present invention, the above object is to install a wind direction plate, which corresponds to the tail of an airplane, behind the blades of a wind turbine, and to use the aerodynamic force of the wind direction plate to control the angle of attack of the blades with respect to the combined speed of the wind and the wind turbine rotation flow. Alternatively, this can be achieved by secondarily controlling the angle of attack of the blades by changing the relative angle of the wind direction plate to the blades according to the wind speed or wind turbine rotation speed.

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, a radial bearing part 3 is provided on a boss part 2 coupled to a wind turbine rotating shaft 1, and a blade 5 is fixed to a shaft 4 rotatably supported by the bearing part 3.
On the other hand, the shaft 4 may be fixed to the boss portion 2 and the blade 5 may be freely rotatably supported with respect to the shaft 4.

When the blades 5 rotate in the direction of the arrow ω, in the present invention, a support 6 is provided on each blade 5 to protrude rearward in the direction of rotation and toward the leeward side, and a wind direction plate 7 is fixed to the tip of the support support 6.

The action of the wind direction plate 7 will be explained with reference to FIG. The rotation axis 0 of the blade 5 is the aerodynamic center of the airfoil of the blade 5 (in a normal airfoil, it is approximately 25% of the chord length from the leading edge of the blade).
) and the center of wind pressure at the selected angle of attack α, and the wind direction plate 7 is located in a direction parallel to the rotation axis 0.

In Figure 2, blade 5 is moving from the left to
Assuming that the blade 5 is moving upward at a speed U while receiving the wind of Vw, the blade 5 is also receiving the wind of the wind speed U from above, so in the end, the blade 5 is moving upward at a speed of Vw.
This means that the wind has a combined velocity W of (1-a) and U(1+b). Here, a and b are called an axial flow interference coefficient and a rotational flow interference coefficient, respectively, and can be calculated from propeller theory. Wind direction board 7
acts in the direction of the airflow W in the same way as the tail of an airplane and maintains the assembly of the blade 5 and the wind direction plate 7 in a constant posture. It is known from wind turbine theory that if the angle between the chord line of the blade 5 and W at this time, that is, the angle of attack α, becomes the angle αm that maximizes the lift-drag ratio of the airfoil, the efficiency of the wind turbine will be the best. Therefore, if the shape, posture, etc. of the wind direction plate 7 are determined so that the angle of attack is αm, the blades 5 will always have the best efficiency with respect to the axis 0, no matter what direction the wind turbine receives the combined speed W. Rotates to follow the rotation position.
That is, the blade pitch can be automatically changed to provide the best efficiency for changing wind speeds.

Note that the shape of the cross section of the wind direction plate 7 is preferably an airfoil shape in order to reduce the increase in rotational resistance due to the wind direction plate 7.

As is clear from the above explanation, the relative angle β of the wind direction plate 7 with respect to the blade 5 influences the angle of attack α of the blade 5, so it is possible to control the angle of attack α by making the relative angle β variable. .

In general, wind energy conversion devices such as generators and heat generators have limited capacity, and their structure and
From the viewpoint of strength, it is common to set a maximum rotation speed limit. In the embodiment shown in FIGS. 3 and 4, the wind direction plate 7 is
This figure shows an over-rotation prevention device that controls the rotational position of the motor using centrifugal force. FIG. 3 shows the cross-sectional shape of an assembly of the blade 5 and the wind deflector 7, which is similar to FIG. , an arm 8 protruding from the wind direction plate 7 and a rod 9 protruding from the blade 5 are connected at point Q.

A centrifugal force type over-rotation prevention device 10 is provided in each blade 5 as a wind direction plate rotation control device for moving the rod 9 forward and backward to rotate the wind direction plate 7 with respect to the blade 5. That is, the bracket 1 fixed to the blade 5
A rod 12 is slidably guided and supported in the axial direction by 1a and 11b, a weight 13 is attached to the outer end of the rod 12, and an inner end of the rod 12 is connected to the rod 9 via a bell crank 14. A compression spring 16 is interposed between the stopper 15a fixed to the bracket 11a and the stopper 15a, so that the stopper 15a is normally brought into contact with the upper surface of the bracket 11b. At this time, the rotational speed of the wind turbine increases and the rod 12 remains stationary until the centrifugal force generated by the weight 13 reaches the initial compressive force F of the spring 16. is unchanged, and the angle of attack of the blade 5 at this time is set to αm, for example. If the windmill rotation speed at which the centrifugal force of the weight 13 is equal to the initial compression force F is defined as the limit start rotation speed, when the rotation speed is exceeded, the rod 12 moves upward while the stopper 15a compresses the spring 16. Move Rod 9 to the left. As a result, the wind direction plate 7 rotates in the direction in which the angle of attack α of the blade 5 becomes smaller.

When the rotational speed further increases and the stopper 15b comes into contact with the lower surface of the bracket 11b, the upward movement of the rod 12 stops and the angle of attack becomes minimum. If this minimum angle of attack is set to the value αo at which the lift force of the blade becomes zero, then
The wind turbine will not speed up any further, and this rotation speed will be the maximum rotation speed limit.

In a normal airfoil, the difference between the angle of attack αo at which the lift force is zero and the angle of attack αm at which the lift-drag ratio is maximum is several degrees, so the amount of movement of the rod 12 during this period is small, and the limit starting rotation is The difference between the number and the maximum rotational speed limit can be set relatively small. This is advantageous in keeping the upper limit of the wind turbine rotation speed substantially constant.

In general, when the maximum wind speed during wind speed fluctuations, including typhoons, can be predicted, the minimum angle of attack is set so that the wind turbine rotation speed that increases due to the maximum wind speed is less than the maximum allowable rotation speed determined by the wind energy conversion device etc. In this case, the lift force of the blade 5 is generally not zero, but since it is often difficult to predict the maximum wind speed, it is safe to set the angle of attack αo at which the lift force is zero as described above. It is.

Although it is possible to set the minimum angle of attack to a value at which the lift is negative in order to speed up the response, this is not preferable because hunting tends to occur.

As shown in FIG. 4, when the over-rotation prevention device 10 is provided on each blade 5, the dead weight of the weight 13 is superimposed on the centrifugal force, and the angle of attack changes depending on the vertical position of the blade. Due to positional adjustment, variations in the characteristics of the springs 16, etc., the attack angles α of the blades 5 may become uneven, which may cause harmful vibrations. In order to prevent such a situation, it is preferable to provide each blade 5 with an attack angle interlocking mechanism.

FIG. 5 shows an example of an angle of attack interlocking mechanism. The blade 5 is rotatably supported by a bearing 17 on a tube shaft 4 fixed to the boss portion 2.
As in the figure, brackets 11a, 11b,
Stoppers 15a, 15b and a spring 16 are provided. The outer end of the rod 12A is guided and supported by the bracket 11a or 11b so as to be able to slide in the axial direction, and the inner end is connected to a link 18 provided within the boss portion 2.

Inside the boss part 2, a short shaft 21 is slidably fitted into a cylinder 20 fixed to a boss part base plate 19 concentrically with the rotating shaft 1, and a circular shape is provided at the tip of the short shaft 21 and the tip inside the boss part 2. A link mechanism 23 is provided for each blade between the connecting seat 22, and a lever 25 is provided for each blade, the tip of which is connected to the outer surface of the boss portion 2, and a weight 24 attached to the rear end. It will be done.
The link mechanism 23 and lever 25 are provided in the same plane as the rod 12A. The link mechanism 23 has a tip connected to the circular connecting seat 22 and a middle portion connected to the rod 12A.
A link 18 that passes through the boss portion 2 and connects to the inner end of the
A link 26 that connects to the rear end, and a link 27 that connects the inner end of the link 26 to the outer circumference of the tip of the short shaft 21.
It consists of. The link 26 is in a direction substantially perpendicular to the rotation axis 1, and the link 27 is in a direction substantially parallel to the rotation axis 1.

When the weight 24 moves in the direction of the arrow due to centrifugal force, the rod 12A is moved upward via the links 26 and 18, pulling the rod 9 to the left and pulling the blade 5.
In this case, the inner end of the link 26 moves the short axis 21 in the direction of the arrow via the link 27. Since the short shaft 21 is also connected to the link mechanism 23 of the other blades 5, the angle of attack of each blade 5 changes simultaneously by an angle corresponding to the length of the movement of the short shaft 21, and the unevenness of the attack angles is eliminated. It doesn't happen.

FIG. 6 shows another embodiment of the angle-of-attack-linked over-rotation prevention device that directly detects wind speed. The blade 5 is rotatably supported on the tube shaft 4 as in FIG. 5, and the rod 12B inserted through the tube shaft 4 is
The outer end is supported by a bracket within the blade 5 and is connected to the rod 9 via a bell crank 14. A sliding shaft 2 in the central axis direction supported by the boss part 2
A resistance disk 29 is fixed to the tip of the rod 12B, and the sliding shaft 28 and the inner end of the rod 12B are connected by a link 30 that is diagonal to the shaft 28.
The rear surface of B is guided and supported by rollers 31. A spring 3 in a cylinder 32 fixed to the boss portion 2 is attached to the sliding shaft 28.
3, and a stopper 34b that determines the forward position of the sliding shaft 28 so as to apply an initial compressive force F to the spring 33 are fixed.

The sliding shaft 28 remains stationary until the wind pressure acting on the resistance disk 29 reaches the initial compressive force F, and the blade angle of attack at this time is set to αm. When the wind speed increases and the wind pressure on the resistance disk 29 exceeds the initial compressive force F, the sliding shaft 28 retreats and moves the rod 12B upward via the link 30, thereby reducing the angle of attack. The wind speed further increases and the stopper 34a closes to the cylinder 3.
2, the blade 5 becomes the angle of attack αo with zero lift or a set angle of attack close to this, and limits the wind turbine rotation speed to the set upper limit value.

In addition to the above-mentioned embodiment, the angle of attack interlocking mechanism for each blade may include a mechanism in which the movement of the sliding shaft 28 is changed to the rotation of the main gear by a cam, and the child gears attached to each rod 12A, 12B, etc. are meshed with the main gear. It is also possible to collectively control the angle of attack of all blades (Japanese Patent Application No. 55-158185).

As described above, the present invention rotatably supports the blades on the boss part of a propeller-type wind turbine, and changes the blade pitch angle using the aerodynamic force of the wind direction plate attached to the rear of each blade, thereby enabling efficient operation of the wind turbine. As a result, pitch angle control of wind turbines does not require complicated and expensive mechanical governor mechanisms or electronic control devices with servo mechanisms, making it possible to control pitch angles at low cost. Since wind turbines can be operated with maximum efficiency, wind turbines can be used economically. Furthermore, even when the wind turbine rotation speed is controlled by rotating the wind direction plate, the rotation of the wind direction plate can be performed by a wind direction plate rotation control device that responds to the wind speed or the wind turbine rotation speed. It has the effect of being able to be constructed at low cost. A servo mechanism may be used to rotate the wind direction plate, but in that case, the blade pitch angle is determined by the aerodynamic force of the wind direction plate, so the servo mechanism only needs to have a small capacity to rotate the wind direction plate, and the blade pitch angle cannot be directly adjusted. Compared to the case where control is performed using a servo mechanism, the capacity of the servo mechanism is significantly smaller. Therefore, the present invention is of great benefit in adapting small wind turbines to a wide range of applications economically and easily.

[Brief explanation of drawings]

Fig. 1 is an elevational view of an embodiment of the present invention, Fig. 2 is a sectional view taken along line A-A in Fig. 1, Fig. 3 is a side view schematically showing the rotating mechanism of the wind direction plate, and Fig. 4. is an elevational view of a centrifugal over-rotation prevention device provided on the blade, FIG. 5 is a longitudinal sectional view of one embodiment of the angle-of-attack interlocking mechanism, and FIG. 6 is a partial longitudinal sectional view of another embodiment of the angle-of-attack interlocking mechanism. It is a front view. DESCRIPTION OF SYMBOLS 1... Wind turbine rotating shaft, 2... Boss part, 4... Radial axis, 5... Blade, 7... Wind direction plate, 10...
...Wind direction plate rotation control device.

Claims (1)

[Scope of Claims] 1. In a propeller-type wind turbine in which the blades are rotatably supported around a radial direction axis on a boss portion fixed to the wind turbine rotating shaft, each blade is provided with a wind direction plate located at the rear in the rotational direction of the blade. In addition to being rotatable around an axis parallel to the direction axis, a wind direction plate is attached to the blade or wind turbine rotating boss via a rod that slides in the radial direction within each blade due to wind pressure or centrifugal force of a weight. A wind direction plate is provided with a rotation control device for rotating the wind direction plate, and the wind direction plate controls the angle of attack of the blade with respect to the direction of the combined velocity of the wind and the rotational flow by the aerodynamic force accompanying the rotation. Propeller type windmill. 2. The propeller-type wind turbine with a wind direction plate according to claim 1, wherein the angle of attack of the blade is an angle of attack at which the lift-drag ratio of the blade is maximized. 3. The wind direction plate rotation control device maintains the angle of attack of the blade at a value that maximizes the lift-drag ratio of the blade when the number of rotations is below a predetermined number, and controls the angle of attack so that the lift force of the blade decreases when the number of rotations exceeds the predetermined number of rotations. A propeller-type wind turbine with a wind direction plate according to claim 1, which is an over-rotation prevention device.