Prime-mover dynamo plants – Electric control – Fluid-current motors
Reexamination Certificate
1999-11-16
2001-06-05
Ponomarenko, Nicholas (Department: 2834)
Prime-mover dynamo plants
Electric control
Fluid-current motors
C290S055000
Reexamination Certificate
active
06242818
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to wind turbines for generating electrical power, particularly to vertical axis wind turbines, and more particularly to such turbines having means for preventing catastrophic failures in high winds.
2. Brief Description of the Prior Art
Wind Turbines provide a source of electrical power as an alternative to fossil fuels to help reduce gaseous emissions and other environmental problems. Wind turbines also provide electrical power in remote areas where power lines have not been strung. Accordingly, numerous wind turbines have been installed in high wind areas in the United States and other countries.
Wind turbines have either horizontal axes or vertical axes of rotation, with each type having different advantages and disadvantages. Vertical axis turbines have, among other advantages, little or no need for a tower on which to mount the turbines. The turbine, gearing electrical generators and the like can generally be mounted at ground level.
Most wind turbines are subject to possible damage from excessively high winds. Vertical axis turbines are less vulnerable to damage from high winds because such turbines are not usually mounted on towers that can be blown over. However, high winds can damage vertical axis turbines by causing them to run at excessively high speeds (RPM), which can cause catastrophic failure of the rotor, gearing, etc.
It is known to provide speed limiters or governors for wind turbines to reduce the risk of damage from high winds and excessively high speed rotation of the turbines. For example, U.S. Pat. No. 5,425,619 to Aglor discloses a horizontal axis turbine having spring-loaded gate flaps which open responsive to predetermined levels of air pressure to spill air through outlets instead of across the air-engaging blades in the turbine. U.S. Pat. No. 3,856,432 discloses a vertical axis turbine having leaves made of resilient material which are unfolded by centrifugal forces at predetermined rotational speeds to interfere with air that would otherwise cause the rotor to speed out of control. U.S. Pat. Nos. 591,962; 1,586,914 and 4,004,861 also disclose systems for controlling the speed of wind turbines.
An improved means is needed for reducing the risk to vertical axis wind turbines from high winds.
A low cost, reliable wind turbine is desired which includes means for reducing the possible risk of excessively high speed operation.
A vertical axis wind turbine is needed that will not destroy itself in high winds.
A wind turbine is also desired that is economical to manufacture.
SUMMARY OF THE INVENTION
This invention satisfies all the above needs for an improved wind turbine. The invention provides a vertical axis wind turbine having a means for automatically maintaining the turbine speed or possibly shutting the turbine down if its rotational speed reaches a predetermined RPM in excessively high winds. This invention also provides a wind turbine that includes electrical power generating means inside the turbine.
This invention has a rotor with a plurality of blades on the rotor and a pivotable door associated with each blade to block or partially block the wind from the blade when the rotor rotates at potentially damaging speeds. The pivot axis for each door is inclined outwardly with respect to the vertical axis of the turbine from the top to the bottom of the turbine so gravitational forces on the door pulls it to an open position that permits the wind to act on the blade. Each door is also responsive to wind forces that push it toward the open position and centrifugal forces that pull it toward a closed position. The turbine is designed to balance the three forces acting on the doors so that the centrifugal forces exceed the sum of the wind forces and gravitational forces when the speed of the rotor approaches potentially damaging RPMs. When the rotor slows, the sum of the gravitational and wind forces exceed the centrifugal forces so that the doors move to or toward the open position to again permit the wind to drive the turbine blades. This invention may further have coils in the rotor and on the support column within the rotor for generating electrical power when the rotor turns in the column.
Accordingly, an object of this invention is to provide a vertical axis wind turbine having a mechanical speed control system.
Another object is to provide a wind turbine having electrical power generating means inside the turbine.
The above and other objects and advantages of this invention will be more fully understood by reference to the following description and the drawings attached hereto.
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Brownlee David W.
Eckert Seamans Cherin & Mellott , LLC
Ponomarenko Nicholas
Radack David V.
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