Sectional vane for vertical axis wind power generator

A sectional vane for vertical axis wind power generator includes a frame unit and a plurality of vane units. The frame unit is fixedly mounted to a main shaft of the wind power generator, and includes an upper frame member and at least one lower frame member. The upper and lower frame members are provided on inner side with an upper and a lower guide rail, respectively. The vane unit includes a vane body having an upper and a lower guide channel provided on a top and a bottom, respectively, corresponding to the upper and the lower guide rail. The vane units are assembled to the frame unit between the upper and the lower frame member through engagement of the guide channels with the guide rails. The sectional vane can be varied in height and area by providing different numbers of lower frame members and vane units.

RELATED APPLICATIONS

This application claims priority to Chinese Application Serial Number 200910008504.7, filed Jan. 23, 2009, which is herein incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to a vane structure, and more particularly to a sectional vane structure for vertical axis wind power generator.

BACKGROUND OF THE INVENTION

Generally, a vertical axis wind power generator utilizes a plurality of vanes to intercept the flow of air currents and according the wind force, so as to drive a main shaft of the wind power generator to rotate for generating electric power. For the purpose of intercepting a large amount of air currents, the vanes of the vertical axis wind power generator usually have a considerably large area and a length as long as 10 to 15 meters. However, it is very troublesome and time-consuming to manufacturing vanes with so large area and length. Also, it is very inconvenient to install and maintain or repair these large vanes.

A vertical axis wind power generator has a vertical main shaft, on which a plurality of vanes are mounted to space from one another along a circumferential surface of the main shaft. Each of the vanes has a front side and a rear side that are generally two corresponding outward curved face and inward curved face, respectively. The inward curved face of the vane is located against the wind to intercept the flow of air currents and accordingly the wind force, so that the vane is push by the wind to thereby drive the main shaft to rotate. Then, the rotating force of the main shaft is transmitted to a plurality of power generator sets for generating electric power.

Since the vanes of the vertical axis wind power generator are sequentially circumferentially spaced around the main shaft, the inward curved rear face of a preceding vane is oriented toward the outward curved front face of a following vane. When the wind blows against the inward curved rear face of one vane, it also blows against the outward curved front face of another diametrically opposite vane. That is, only the wind blowing to the inward curved rear face of the vane is useful to effectively rotate the main shaft, while the wind blowing to the outward curved front face of the vane simply forms a resistance to the rotation of the main shaft.

It is noted the vanes for the conventional vertical axis wind power generator all are a complete plate without any opening formed thereon. When the wind blows to the outward curved front face of the vane, the outward curved front face functions to guide the wind to outer sides of the vane to thereby reduce the air resistance thereto. Nevertheless, the relatively large area of the vane would still block the wind to thereby reduce the overall push produced by the wind against the inward curved rear faces of other vanes. Since the wind force capable of driving the main shaft to rotate is reduced, the effect of wind power generation is disadvantageously reduced accordingly.

SUMMARY OF THE INVENTION

A primary object of the present invention is to provide a sectional vane for vertical axis wind power generator to enable easy manufacturing, assembling, installation and maintenance of the vane.

Another object of the present invention is to provide a sectional vane for vertical axis wind power generator, which, on the one hand, reduces air resistance thereto and, on the other hand, allows effective interception of the wind force for driving the main shaft of the wind power generator to rotate.

To achieve the above and other objects, the present invention provides a plurality of sectional vanes for mounting around and spacing along a main shaft of a vertical axis wind power generator. According to a preferred embodiment of the present invention, each of the sectional vanes includes a frame unit and a plurality of vane units. The frame unit includes a root section for fixedly mounted to an outer periphery of the main shaft of the vertical axis wind power generator, an inner end plate for mounting to a free end of the root section, an outer end plate, an upper frame member connected at two opposite ends to and between upper portions of the inner and the outer end plate, and at least one lower frame member connected at two opposite ends to and between lower portions of the inner and the outer end plate. The upper frame member is provided on one side facing toward the lower frame member with a longitudinally extended upper guide rail, and the lower frame member is provided on one side facing toward the upper frame member with a longitudinally extended lower guide rail corresponding to the upper guide rail. Each of the vane units includes a vane body, which is provided on a top and a bottom with an upper and a lower guide channel, respectively, and is slidably assembled to and between the upper and the lower frame member through engagement of the upper and the lower guide channel with the upper and the lower guide rail, respectively. The number of vane units that are to be assembled to the frame unit is determined depending on the length of the upper and lower frame members and the number of the lower frame members. Therefore, the sectional vane according to the present invention can be varied in length and area according to actual need.

Preferably, there is a plurality of lower frame members being parallelly spaced below the upper frame member. In this case, the lower frame members are respectively provided on each of two opposite sides thereof with a longitudinally extended guide rail. The vane units can be slidably engaged with and guided by the guide rails to thereby be assembled to and between the parallelly spaced lower frame members. Therefore, the sectional vane according to the present invention can be varied in area by providing different numbers of lower frame members and vane units.

According to an embodiment of the vane unit for the sectional vane of the present invention, the vane unit includes a vane body, a first arcuate guide bar, an openwork screen, and a first movable baffle assembly. The vane body has a body portion that defines a rearward recess, and includes a front plate portion, on which a through hole is formed. The first arcuate guide bar is located in the rearward recess, and has a first end and an opposing second end; the second end is fixedly connected to the body portion and the first end is located at a center of the through hole. The openwork screen is fitted in the through hole and connected to the first end of the first arcuate guide bar. The first movable baffle assembly is located in the rearward recess and slidably fitted around the first arcuate guide bar, and is pivotally turnably connected to the front plate portion via a baffle support bar, such that the first movable baffle assembly openably covers the openwork screen from one side adjacent to the rearward recess. When the rearward recess of the vane is located against the wind, the first movable baffle assembly is blown by the wind to cover the openwork screen and accordingly closes the through hole on the front plate portion for the rearward recess of the vane body to effectively intercept the wind. On the other hand, when the rearward recess of the vane is located before the wind, the first movable baffle assembly naturally opens the through hole on the front plate portion to reduce the air resistance to the rotation of the vane. That is, the vane of the present invention with the rearward recess located against the wind can effectively utilize the wind force without being adversely affected by an opposing vane that has a rearward recess located before the wind at the same time. Thus, the main shaft of the wind power generator can be more easily driven by the vanes to rotate.

Preferably, the front plate portion has an outward curved front surface, and an area of the outward curved front surface surrounding the through hole is formed into a bell-shaped sunken portion. The outward curved front surface can advantageously guide air currents to outer sides of the vane body, and the sunken portion can advantageously guide part of the air currents through the through hole to outer sides of the vane body.

Preferably, the openwork screen has a sleeve portion and a screen body connected to and located around the sleeve portion. The sleeve portion is fitted around the first end of the first arcuate guide bar. The screen body is provided with a plurality of openings and is fixedly connected at an outer periphery thereof to an inner peripheral wall of the through hole. Therefore, the openwork screen is fitted in the through hole and supported by the first arcuate guide bar.

Preferably, the first movable baffle assembly includes a first sleeve and a first movable baffle connected to and located around an end of the first sleeve. The first sleeve is slidably fitted around the first arcuate guide bar, and the first movable baffle normally covers the openwork screen from one side adjacent to the rearward recess. Thus, the first movable baffle assembly openably covers the openwork screen and is supported and guided by the first arcuate guide bar to move between an opened position and a closed position to open and cover the openwork screen, respectively.

Preferably, a first buffer spring is provided between the openwork screen and the first movable baffle assembly, and a first and a second magnetic ring having the same polarity are provided on the first buffer spring and the first movable baffle assembly at contact faces thereof to buffer the impact between the first movable baffle assembly and the openwork screen and accordingly, avoid damaged parts and noise caused by such impact.

Preferably, the vane unit further includes a stop assembly, which includes a stop ring fixedly mounted to the first arcuate guide bar near the second end thereof, and a stop spring arranged on the first arcuate guide bar to one side of the stop ring facing toward the first end. The stop ring functions to limit a maximum angle by which the first movable baffle assembly can be pivotally turned open. Therefore, the first movable baffle assembly is protected against damage due to an exceeded open angle caused by an extremely strong wind. The stop spring can buffer the impact between the first movable baffle assembly and the stop ring.

Preferably, the stop assembly further includes a holding device, which is pivotally turnably connected to one lateral side of the stop ring. The holding device includes a control lever and a hook connected to the control lever. And, the first movable baffle assembly is provided at positions corresponding to the control lever and the hook with a push bar and a retaining ring, respectively. When the first movable baffle assembly is blown open by a strong wind and stopped by the stop ring from turning any further, the push bar will strike against the control lever of the holding device at the same time, bringing the hook to engage with the retaining ring. Thus, the first movable baffle assembly is held to the fully opened position, allowing the vane to rotate at a reduced speed to avoid damaged parts of the vane due to undesirable quick rotation of the vane under extremely strong wind.

Preferably, the holding device further includes an outward projected release lever for disengaging the hook from the retaining ring.

Preferably, an electromagnetic valve is provided above the control lever for disengaging the hook from the retaining ring.

According to another embodiment of the vane unit for the present invention, the vane unit includes a vane body, a first arcuate guide bar, an openwork screen, a first movable baffle assembly, and a second movable baffle assembly. The vane body has a body portion that defines a rearward recess and includes a front plate portion, on which a through hole is formed. The first arcuate guide bar is located in the rearward recess, and has a first end and an opposing second end. The second end is fixedly connected to the body portion and the first end is located at a center of the through hole. The openwork screen is fitted in the through hole and connected to the first end of the first arcuate guide bar. The first movable baffle assembly has openings formed thereon and is located in the rearward recess of the vane body behind the openwork screen. The first movable baffle assembly includes a second arcuate guide bar in the form of a sleeve slidably fitted around the first arcuate guide bar, and is connected to the front plate portion of the vane body via a pivot point on a baffle support bar, so that the first movable baffle assembly is turnable about the pivot point to openably cover the openwork screen from one side adjacent to the rearward recess. The second arcuate guide bar has a proximal end and a distal end, and a radially outward extended flange formed around the distal end. The second movable baffle assembly is located in the rearward recess of the vane body behind the first movable baffle assembly, and is slidably fitted around the second arcuate guide bar to openably cover the first movable baffle assembly from one side adjacent to the rearward recess. When the rearward recess of the vane body is located against the wind, the first and the second movable baffle assembly on the vane body are located at a closed position to cover the openwork screen and the through hole, allowing the rearward recess to effectively intercept the wind force; and when the rearward recess of the vane body is located before the wind, the first and the second movable baffle assembly are naturally opened, allowing the wind to quickly move through the through hole to outer sides of the vane body without producing an increased air resistance to the rotating vane body. That is, the vane with the rearward recess located against the wind can effectively utilize the wind force without being adversely affected by an opposing vane that has the rearward recess located before the wind at the same time. Thus, the main shaft of the wind power generator can be more easily driven by the vanes to rotate.

Preferably, a second buffer spring is provided between the first and the second movable baffle assembly to buffer the impact therebetween, so as to avoid damaged parts and noise caused by such impact.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described with some preferred embodiments thereof. For the purpose of easy to understand, elements that are the same in the illustrated preferred embodiments are denoted by the same reference numerals.

Please refer toFIG. 1that is a fragmentary perspective view showing a plurality of sectional vanes according to the present invention is mounted around and spaced along a main shaft3of a wind power generator, and toFIG. 2that is an exploded perspective view showing one of the sectional vanes ofFIG. 1.

As shown, the sectional vane for vertical axis wind power generator according to a first embodiment of the present invention includes a frame unit1and a plurality of vane units2. The frame unit1is fixedly mounted to a main shaft3of the wind power generator, and the vane units2are removably assembled to the frame unit1.

In practical implementation, the frame unit1includes a root section11, an inner end plate12, an outer end plate13, an upper frame member14, and at least one lower frame member15. In the embodiment illustrated inFIGS. 1 and 2, there is shown only one lower frame member15.

The root section11is fixedly connected at an end to an outer periphery of the main shaft3. The inner end plate12is connected to a free end of the root section11. The upper frame member14is connected to and between upper portions of the inner end plate12and the outer end plate13. The lower frame member15is connected to and between lower portions of the inner end plate12and the outer end plate13. The upper frame member14is provided on one side facing toward the lower frame member15with a longitudinally extended upper guide rail141, and the lower frame member15is provided on one side facing toward the upper frame member14with a longitudinally extended lower guide rail151corresponding to the upper guide rail141. The upper frame member14and the lower frame member15are spaced from each other by a predetermined distance, which is just large enough for installing the vane units2between the upper and the lower frame member14,15.

The vane unit2includes a vane body21, which is provided on a top and a bottom with an upper guide channel21aand a lower guide channel21b, respectively.

The vane units2(three are shown inFIGS. 1 and 2) can be slidably assembled to the frame unit1between the upper and the lower frame member14,15through engagement of the upper and the lower guide channel21a,21bwith the upper guide rail141of the upper frame member14and the lower guide rail151of the lower frame member15, respectively. Then, the outer end plate13is covered onto an outer lateral side of the outermost vane unit2to complete the assembly of the vane units2to the frame unit1and provide a complete sectional vane of the present invention.

In practical implementation, the guide rails141,151can be dovetail slides and the guide channels21a,21bcan be dovetail grooves to provide increased stability in the engagement of the guide rails141,151with the guide channels21a,21b

With the above arrangements, the sectional vane of the present invention provides the following advantages: (1) parts and components for forming the vane units2and the frame unit1can be made of an aluminum material through extrusion, allowing the vane units2and the frame unit1to be mass-produced; (2) the length and size of the sectional vane can be changed simply by changing the length of the upper and lower frame members14,15and the number of the vane units2, allowing easy and convenient production and assembling of the sectional vane; and (3) any damaged part or component can be separately replaced without the need of changing the whole vane, allowing easy and convenient maintenance of the vane.

The vane unit2for the sectional vane of the present invention is provided with a movable baffle structure to close and open a through hole formed on the vane body21of the vane unit2. Please refer toFIGS. 3 to 5, in which the structure of a first embodiment of the vane unit2is shown.

As shown, the vane unit2according to the first embodiment thereof includes a vane body21, a first arcuate guide bar22, an openwork screen23, and a first movable baffle assembly24.

The vane body21includes a body portion210that defines a rearward recess219. In practical implementation, the body portion210includes a front plate portion211, an upper plate portion212and an opposing lower plate portion213extended from an upper and a lower edge of the front plate portion211, and a left plate portion214and an opposing right plate portion215extended from a left and a right edge of the front plate portion211. The rearward recess219is formed between the front, the upper, the lower, the left and the right plate portion211,212,213,214,215to effectively intercept the flow of air currents and wind force.

The front plate portion211is provided with a through hole216, and has an outward curved front surface217with an area surrounding the through hole216formed into a substantially bell-shaped sunken portion218. That is, the through hole216is formed on the front plate portion211at a bottom of the sunken portion218.

The first arcuate guide bar22is located in the rearward recess219, and has a first end221and an opposing second end222. The second end222is fixedly connected to a predetermined position on the body portion210, such as the upper plate portion212. The first end221, is located at a center of the through hole216on the body portion210.

The openwork screen23is mounted in the through hole216on the body portion210and connected to the first end221of the first arcuate guide bar22. In practical implementation, the openwork screen23includes a sleeve portion231and a screen body232connected to and located around the sleeve portion231. The sleeve portion231is fitted around the first end221of the first arcuate guide bar22, and the screen body232is fixedly connected at an outer periphery thereof to an inner peripheral wall of the through hole216. On the screen body232, there is provided a plurality of openings2321. With the above arrangements, the openwork screen23is fitted in the through hole216.

The first movable baffle assembly24is located in the rearward recess219behind the openwork screen23and slidably fitted around the first arcuate guide bar22. The first movable baffle assembly24is connected to the front plate portion211of the vane body21via a pivot point2411on a baffle support bar241, so that the first movable baffle assembly24is turnable about the pivot point2411into the rearward recess219or toward the openwork screen23to openably close the through hole216and accordingly, the openwork screen23. In practical implementation, the first movable baffle assembly24includes a first sleeve242and a first movable baffle243connected to and located around an end of the first sleeve242. The first sleeve242is slidably fitted around the first arcuate guide bar22, and the first movable baffle243normally covers the openwork screen23from one side adjacent to the rearward recess219. That is, the first arcuate guide bar22is not only connected to the openwork screen23for supporting the same, but also functions to guide the first movable baffle assembly24to an opened position or a closed position while firmly supporting the first movable baffle assembly24thereon.

As can be seen fromFIG. 3, when the wind blows against the vane body21of the vane unit2from the side with the rearward recess219, the first movable baffle assembly24is blown toward the openwork screen23to thereby close the openings2321on the openwork screen23, allowing the rearward recess219of the vane body21of the vane unit2to effectively intercept the wind for driving the main shaft3to rotate.

While the wind blows against the rearward recess219of the above-mentioned vane unit2, it also blows against the outward curved front surface217of the front plate portion211of a diametrically opposing vane unit2, as shown inFIG. 4. At this point, while some part of the air currents of the wind is guided by the outward curved front surface217toward outer sides of the opposing vane unit2, other part of the air currents of the wind acting on the front plate portion211is guided into the sunken portion218to pass through the openings2321on the openwork screen23and blow against the first movable baffle assembly24, bringing the first movable baffle assembly24to turn about the pivot point2411of the baffle support bar241while being guided by the first arcuate guide bar22to move away from the openwork screen23to open the through hole216. At this point, with the through hole216on the opposing vane unit2in an opened state, the wind is no longer blocked by the opposing vane unit2but can pass through the openings2321on the openwork screen23and be guided to outer sides of the opposing vane unit2. As a result, the air resistance at the opposing vane unit2is reduced.

Thus, according to the first embodiment of the vane unit2for the present invention, when the wind force acts on the rearward recess219of one of the vane unit2on the main shaft3of the vertical axis wind power generator, a diametrically opposing vane unit2thereof can quickly remove the air resistance at the same time to thereby eliminate any significant obstruction to the wind force by the opposing vane unit2, allowing the sectional vanes to produce increased push for driving the main shaft3of the wind power generator to rotate.

A first buffer spring244is provided between the openwork screen23and the first movable baffle assembly24. When the first movable baffle assembly24is turned toward the openwork screen23to close the same, the first buffer spring244functions to buffer the impact of the first movable baffle assembly24against the openwork screen23and accordingly, avoid damaged parts and noise caused by such impact. Further, a first magnetic ring248and a second magnetic ring249that have the same polarity are respectively provided on the first buffer spring244and the first movable baffle assembly24at contact faces thereof, so that magnetic repulsion between the first and the second magnetic ring248,249further buffers the impact between the first movable baffle assembly24and the openwork screen23.

Please refer toFIGS. 3 to 5, particularlyFIG. 5. The first embodiment of the vane unit2for the present invention further includes a stop assembly25, which includes a stop ring251and a stop spring252. The stop ring251is fixedly mounted to the first arcuate guide bar22near the second end222, and the stop spring252is arranged on the first arcuate guide bar22to one side of the stop ring251facing toward the first end221. The stop ring251functions to limit a maximum angle by which the first movable baffle assembly24can be pivotally turned open. Therefore, the first movable baffle assembly24is protected against damage due to an exceeded open angle caused by an extremely strong wind, such as typhoon. The stop spring252can buffer the impact between the first movable baffle assembly24and the stop ring251.

The stop assembly25further includes a holding device253, which is pivotally turnably connected to one lateral side of the stop ring251. The holding device253includes a control lever2531and a hook2532connected to the control lever2531. And, the first movable baffle assembly24is provided at positions corresponding to the control lever2531and the hook2532with a push bar245and a retaining ring246, respectively. When the first movable baffle assembly24is blown open by a strong wind and stopped by the stop ring251from turning any further, the push bar245will strike against the control lever2531of the holding device253at the same time, bringing the control lever2531to pivotally turn upward and accordingly, bringing the hook2532to pivotally turn downward to engage with the retaining ring246. Thus, the first movable baffle assembly24is held to the fully opened position, allowing the sectional vane to rotate at a reduced speed and avoid damaged parts of the sectional vane due to undesirable quick rotation under extremely strong wind.

The holding device253also includes an outward projected release lever2533. When the strong wind is no longer a problem, the release lever2533can be manually pulled to disengage the hook2532from the retaining ring246. At this point, the first movable baffle assembly24is not bound to the stop assembly25but can freely pivotally turn between the fully opened position and the fully closed position in response to different wind directions to open or close the openwork screen23.

Alternatively, the holding device253can be electrically controlled to release the hook2532from the retaining ring246. In this case, an electromagnetic valve2534is mounted on the first arcuate guide bar22to locate above the control lever2531. When the strong wind is no longer a problem, the electromagnetic valve2534can be electrically controlled to strike the control lever2531downward, so that the hook2532is brought to turn reversely and thereby disengage from the retaining ring246.

To ensure stable rotation of the sectional vanes, a steel cable4is connected to and between each of the upper frame member14and the main shaft3, and any two adjacent outer end plates13, as can be seen inFIG. 1.

FIGS. 6,7and8are sectioned side views of a second embodiment of the vane unit2for the present invention. The second embodiment of the vane unit2is generally structurally similar to the first embodiment; except for a second movable baffle assembly26for openably covering the first movable baffle assembly24. That is, the vane unit2according to the second embodiment thereof includes two overlapping movable baffle assemblies to reduce the air resistance as quick as possible when the outward curved front surface of the vane unit faces against the wind.

The portions of the vane unit2of the second embodiment that are different from the vane unit of the first embodiment will now be described in more details. In the vane unit2of the second embodiment, the first movable baffle assembly24has openings formed thereon, and is located in the rearward recess219of the vane body21behind the openwork screen23. The first movable baffle assembly24includes a second arcuate guide bar247, which is in the form of a sleeve slidably fitted around the first arcuate guide bar22. As in the vane unit2of the first embodiment, the first movable baffle assembly24is connected to the front plate portion211of the vane body21via a pivot point2411on a baffle support bar241, so that the first movable baffle assembly24is turnable about the pivot point2411into the rearward recess219or toward the openwork screen23to openably close the through hole216. As can be seen inFIG. 6, the second arcuate guide bar247has a proximal end2471and a distal end2472, and a radially outward extended flange2473is formed around the distal end2472.

In practical implementation, the first movable baffle assembly24includes a first sleeve242located around the proximal end2471of the second arcuate guide bar247, and a first movable baffle243connected to and located around an end of the first sleeve242. The first movable baffle243normally covers the openwork screen23from one side adjacent to the rearward recess219, and is provided with a plurality of openings2431.

The second movable baffle assembly26is located in the rearward recess219of the vane body21and slidably fitted around the second arcuate guide bar247. The second movable baffle assembly26normally openably covers the first movable baffle assembly24from one side adjacent to the rearward recess219. In practical implementation, the second movable baffle assembly26includes a second sleeve261and a second movable baffle262connected to and located around the second sleeve261. The second sleeve261is slidably fitted around the second arcuate guide bar247, and the second movable baffle262normally closes the openings2431on the first movable baffle assembly24from one side adjacent to the rearward recess219.

As shown inFIG. 6, when the rearward recess219on the vane unit2is located against the wind, the second movable baffle assembly26is blown by the wind toward the first movable baffle assembly24to close the openings2431, and the first movable baffle assembly24is also blown by the wind toward the openwork screen23to close the openings2321, making the whole vane unit2a complete plate without any opening. At this point, the rearward recess219can effectively intercept the wind force to thereby drive the main shaft3to rotate.

Please refer toFIG. 7. While the wind blows against the rearward recess219of the above-mentioned vane unit2, it also blows against the outward curved front surface217of the front plate portion211of an opposing vane unit2that is located diametrically opposite to the above-mentioned vane unit2. At this point, while some part of the air currents of the wind is guided by the outward curved front surface217toward outer sides of the opposing vane unit2, other part of the air currents of the wind acting on the front plate portion211is guided into the sunken portion218to pass through the openings2321on the openwork screen23and blow against the first movable baffle assembly24, bringing the first movable baffle assembly24to turn about the pivot point2411of the baffle support bar241while being guided by the first arcuate guide bar22to move away from the openwork screen23to an opened position. Meanwhile, the wind passes through the openings2431on the first movable baffle assembly24to act on the second movable baffle assembly26, bringing the second movable baffle assembly26to move away from the first movable baffle assembly24while sliding along the second arcuate guide bar247.

At this point, with the through hole216and the first and the second movable baffle assembly24,26on the opposing vane unit2in an opened state, the wind is no longer blocked by the opposing vane unit2but can pass through the openings2321on the openwork screen23and the openings2431on the first movable baffle assembly24to be guided to outer sides of the opposing vane unit2. As a result, the air resistance at the opposing vane unit2is reduced.

A second buffer spring263is provided between the first movable baffle assembly24and the second movable baffle assembly26. When the second movable baffle assembly26is moved toward the first movable baffle assembly24to close the same, the second buffer spring263functions to buffer the impact of the second movable baffle assembly26against the first movable baffle assembly24. Therefore, damaged parts and noise caused by such impact can be avoided.

Similarly, a stop assembly25is provided on the first arcuate guide bar22near the second end222thereof. The stop assembly25includes a stop ring251and a stop spring252, which provide the same functions as in the first embodiment. And, the stop assembly25further includes a holding device253, which is pivotally turnably connected to one lateral side of the stop ring251. The holding device253includes a control lever2531and a hook2532connected to the control lever2531. However, in the second embodiment of the vane unit2, the push bar245and the retaining ring246corresponding to the control lever2531and the hook2532, respectively, are provided on the flange2473of the second arcuate guide bar247of the first movable baffle assembly24. When the first movable baffle assembly24and the second movable baffle assembly26are blown open by a strong wind, they can still be held to the stop assembly25through engagement of the hook2532of the holding device253with the retaining ring246, just the same as in the first embodiment of the vane unit2.

Similarly, the holding device253further includes an outward projected release lever2533and an electromagnetic valve2534is provided to locate above the control lever2531, both of which can be used to release the hook2532from the retaining ring246.

With the vane unit of the present invention, when the rearward recess219of the vane unit2is located against the wind, the movable baffle assembly or assemblies24,26on the vane unit2are located at a closed position to close the openwork screen23and the through hole216, allowing the rearward recess219to effectively intercept the wind force; and when the rearward recess219of the vane unit2is located before the wind, the movable baffle assembly or assemblies24,26are naturally moved to an opened position, allowing the wind to quickly move through the through hole216on the vane unit2to outer sides of the vane unit2without producing an increased air resistance to the rotating vane. Further, since the movable baffle assemblies24,26are supported and guided by the arcuate guide bars22,247while they are blown to the closed position or the opened position, the movable baffle assemblies24,26can maintain firm structure and stable operation. Moreover, with the stop assembly25, the sectional vane can be protected against exceeded turning angle under strong wind, and accordingly, the wind power generator is protected against damage possibly caused by the excessively turned vanes.

It is noted the lower frame member15is not limited to one in number. Instead, the sectional vane according to the present invention can have a plurality of lower frame members15being parallelly spaced below the upper frame member14. In a second embodiment of the present invention as shown inFIGS. 9 and 10, there are two lower frame members15parallelly spaced below the upper frame member14. In this case, a part of the lower frame members15that is located between the upper frame member14and the lowest one of the lower frame members15are respectively provided on an upper side thereof with a longitudinally extended lower guide rail151and on a lower side thereof with a longitudinally extended upper guide rail141. Thus, a plurality of vane units2can be assembled to the frame unit1between the upper frame member14and the lower frame member15directly below the upper frame member14, as well as between any two adjacent lower frame members15through engagement of the upper and the lower guide channels21a,21bwith corresponding upper guide rails141and lower guide rails151, respectively. Thus, the sectional vane according to the present invention can be varied in height and in area by providing different numbers of lower frame members15and vane units2, and accordingly, has very good applicability.