Patent CA-2158491-A1 (CA)
Title: Vertical axis wind turbine
Inventor: YEARWOOD WILLIAM A
IPC: F03D7/06
Filed: 1995-09-18
Abstract: A vertical axis wind turbine apparatus, for converting the kinetic energy of the wind into usable force in a rotary manner as to turn a mill or drive a generator suitable for the home or business. The turbine apparatus consists of three fixed flat vanes, mounted vertically between two flat horizontal discs. The vanes are bent at both ends, at precise angles and different locations from their respective ends. There are three movable control vanes which are mounted 15 degrees behind the fixed vanes in a clockwise rotation. The movable or adjustable vanes are controlled by vertical shafts which can be adjusted to various positions while the turbine is in operation. Adjusting the movable vanes affects the pressure and velocity within the turbine, causing changes in the turbine's speed. The fixed vanes are positioned at 120 degree intervals in rotation from each other and 55 degrees off centre to the turbines pivot point. The vanesare all positioned so as to allow the wind constant flow through the turbine at all times, even when stopped. The adjustable vanes, when in the working mode, will increase the wind velocity and at the same time direct the force towards the vanes that are ahead in rotation and are moving out of the wind's direct force. The adjustable vanes cause a nozzle effect on the blind vanes for up to an additional 90 degrees in the null area ofrotation. From that point there is some negative or reverse effect, but only on the fixed vanes since at that point the adjustable vanes are shielded. Because the area of wind contact on the rear of the fixed vanes is 20% of the area in contact with the wind on the front or positive side of the vanes, the negative effect is overwhelmed and the turbine keeps on turning. To control the adjustable vanes, a worm gear device with links and arms turns the shafts supporting the adjustable vanes from above the turbine. Power to operate this device is fed through carbon brushes and slip rings from below the turbine. Very low current is used to reduce wear on the slip rings and brushes. The adjustable vanes can be positioned to cause a perfect balance of wind pressure on both sides of the turbine, in order to bring the rotation to a complete stop. In the event of mechanism failure, the adjustable vanes will act from centrifugal force to limit the turbine's speed. The turbine is fitted with a centre hub that must be of a specific dimension in order to form a nozzle area in combination with the two vanes. (see specifications.) Two sealed ball bearings are fitted in the hub, one each at the top and bottom. The complete assembly is then mounted on a hollow axle which extends below the turbine and slip rings into an adapter bracket. The complete assembly is mountedon a suitable tower. The drive is taken from the top of the turbine via a drive flange and drive shaft. The drive flange is bolted through the upper disc and into the centre hub. The drive shaft is keyed to the drive flange and extends down through the hollowaxle to the load below the turbine. A centering bearing is fitted in the bottom of the support bracket, in order to keep the drive shaft in alignment with the load.     In areas where the wind direction is constant within 30 degrees this turbine can be mounted horizontally, on the crest of a beach or hill where the wind speed is usually higher. With the use of aluminum sheets and/or honeycomb panels, this turbine will be very simple to construct. Needing only close radius bends on flat sheets, with standard size ball bearings, and the use of a metal turning lathe, a 2 kilowatt unit can be built for $800.00 Cdn. An old TV antenna tower will serve as a suitable tower for the turbine. This turbine will not harm migratory birds, as they will be deflected or simply pass through the turbine. The speed of the turbine will be between 600 and 1,000 RPM. The rotor is designed to start with only a 7 MPH wind, and noise levels will be nearly zero.