Prime-mover dynamo plants – Fluid-current motors – Wind
Reexamination Certificate
2001-02-15
2002-10-15
Ponomarenko, Nicholas (Department: 2834)
Prime-mover dynamo plants
Fluid-current motors
Wind
C290S044000, C416S031000
Reexamination Certificate
active
06465901
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a pitch control system for controlling the pitch of one or more blades. The pitch control system of the present invention is useful in any device that uses or converts the power of a moving fluid, or any device that transfers energy to, or generates movement in, a fluid. Such devices include windmills, wind motors, wind machines, wind turbines, water turbines and the like. More particularly, the present invention relates to a device for using the power of a moving fluid or generating movement in a fluid (such as a windmill, a wind motor, wind machine or wind turbine, water turbine, etc.) having radially placed blades capable of being rotated, and having a pitch control system for regulating the pitch of the blades, wherein the pitch control system comprises a pitch change shaft, means for translating the pitch change shaft in a horizontal direction, and coupling means between the pitch change shaft and the blades, said coupling means effecting a change in the pitch of the blades upon translation of the pitch change shaft.
The present invention furthermore relates to a hub for a windmill, wind motor, wind machine, wind turbine, etc. comprising a pitch control system.
A typical windmill, wind motor, wind machine or wind turbine comprising a pitch change element is known from European patent application EP-A-21810. Such a known device comprises a pitch change shaft extending in a hub of the device. The change shaft extends horizontally, and a toggle means are attached to the pitch change shaft. A change in position of the change shaft changes the position of the toggle means, which causes an arm, attached at one end to the toggle means and at the other end to an axis of a blade, to move, thereby, rotating the axis of the blade. The efficiency on the pitch system and of the device as a whole is dependent on a number of factors, among which the precision in pitch angle control is an important factor. Wear and tear are also important since they influence, among others the down time of a system (time needed for repairs and thus improductive) and the life time of a device. Wear and tear furthermore may after some time, result is a loss of precision in pitch control.
In the known system the toggle means exert transversal forces at right angles to the axis of the pitch change shaft directly on the pitch change shaft. Transversal forces on the pitch change shaft have the effect that rather than a movement of the pitch change shaft causing a change in the pitch of the system, in seeking the path of least resistance, a movement of the pitch change shaft causes a twisting of the pitch change shaft. Such a twisting causes wear and tear on the pitch change shaft. Such wear and tear ultimately necessitates repair of the pitch change shaft and thereby reduces the efficiency of the device. The transversal forces may even lead to the destruction of the pitch change shaft system. Equally or even more important is the effect that this twisting has on the precision in pitch angle control. A movement of the pitch change shaft results in a twisting of the pitch change system or partially in a twisting of the pitch change system and partially in a pitch change of the blades. The relation between the position of the pitch change shaft and the pitch angle of the blades thus becomes less precise (or even imprecise) and consequently the pitch angle control is less precise. A less precise pitch angle control reduces the efficiency of the device.
It is remarked that U.S. Pat. No. 4,534,705, patent abstracts of Japan, vol. 009, No. 034, and the abstract of JP 59 176472 each show devices having sliding means that slide over a central common shaft and to which pivoting means, coupled to the blades are provided. A change in position of the sliding means relative to the central shaft changes the pitch of the blades. The toggle means exert, via the sliding means transversal forces on the central shaft.
U.S. Pat. No. 4,257,736 discloses a wind mill which also does not comprise, for each blade, either a guide shaft and guide shaft sliding means, or first and second sub-coupling means. The blades are pivotably connected between a pair of parallel spaced plates such that the blade angle is adjusted in accordance with the relative spacing of the plates. This known device can basically only operate at two biasing arrangements and has very limited pitch control.
French Patent application FR 2355179 discloses a wind machine having a central axis to which side bars are connected, the side bars being movable in a direction along the central axis. Movement of the side bars changes the position of the blades.
Accordingly, it is desirable to provide a more efficient pitch control system having improved pitch angle control and reduced wear and tear on the pitch change shaft.
The mentioned and further objects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.
SUMMARY OF THE INVENTION
The present invention provides pitch control systems, and devices using the same, having improved pitch angle control and reduced wear and tear on the pitch change shaft.
A device in accordance with the present invention includes coupling means comprising, for each blade, a guide shaft extending substantially parallel to each other and substantially parallel to the pitch change shaft. The coupling means further comprises first sub-coupling means coupling the pitch change shaft to the relevant guide shaft, said first sub-coupling means comprising guide shaft sliding means, and second sub-coupling means coupling the guide shaft sliding means to the relevant blade.
In a device in accordance with the present invention, the transversal forces exerted on the pitch change shaft perpendicular to the pitch change shaft axis are strongly reduced, due to the presence of the guide shafts extending substantially in parallel to the pitch change shaft. This enables better pitch control and reduces wear and tear. For a wind turbine this means better power control, for a wind machine this means stronger winds at the same power.
In one embodiment, the guide shafts are placed at substantially equal distances from the pitch change shaft, and arranged in a substantially symmetrical arrangement around the pitch change shaft. This provides for a symmetric pattern of reaction forces on the guide shaft, thus strongly reducing or even eliminating asymmetric loads on the central pitch change shaft.
The wear and tear on the guide shafts and any asymmetric forces the guide shafts exert on the pitch change shaft are also reduced and preferably minimised. To this end each guide shaft is preferably provided with adjustment means for adjusting the position and orientation of the said guide shaft. Such adjustment means enables the position of each guide shaft relative to the other guide shaft(s) and the pitch change shafts as well as their mutual parallelism to be controlled. The overall position of the guide shaft governs their mutual distances, whereas the orientation governs the (lack of) mutual parallelism. This allows for precision alignment of the guide shafts, which enables a further reduction or even elimination of internal hyperstatic reaction forces in the pitch system, enabling an improved pitch angle control and reduced wear and tear.
In one embodiment, the adjustment means comprises two or more adjustment sub-means separated from each other by some distance along the guide shaft. By using two or more adjustment sub-means separated some distance along the guide shaft the orientation (and thereby the mutual parallelism of the guide shafts) is more easily controllable.
In one embodiment, a first and a second adjustment sub-means are located at or near either end of each guide shaft. Such an arrangement provides for a large freedom in regulating/changing the orientations of the guide shafts, and furthermore the risk of interference with the sliding means is reduced. In one embodiment, each first and second adjustment sub-means includes
3
or more adjust
Ponomarenko Nicholas
Townsend and Townsend / and Crew LLP
Turbowinds N.V./S.A.
LandOfFree
Device for using wind power or generating wind and pitch... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Device for using wind power or generating wind and pitch..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device for using wind power or generating wind and pitch... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2928830