CA1045038A

CA1045038A - Vertical axis wind turbine

Info

Publication number: CA1045038A
Application number: CA279,895A
Authority: CA
Inventors: James Cameron
Original assignee: Individual
Current assignee: Individual
Priority date: 1977-06-06
Filing date: 1977-06-06
Publication date: 1978-12-26

Abstract

ABSTRACT

Vertical axis wind turbines are known to have a number of vanes attached by horizontal arms extending from a central hub.
In this invention, the vanes are elastically pivoted on the arms in a tangential position allowing the combined effects of air pressure, elastic force and blade inertia to deflect the moving vanes to an aerodynamically efficient attitude.

Description

~45~31~
VERTICA~ AXIS WIND TURBINE

This invention relates to an apparatus for extracti-~g energy from wind.
It is common in vertical axis wind turbines to have a number of straight airfoil vanes vertically clisposed around and attached to a central spindle by means of radial, horizontal arms, or to have curved airfoil vanes, vertically disposed, extending radially in an arc from a central spindle. One problem encountered with these types of turbines is their incapacity to accelerate to an efficient rotational velocity without resort to additional starting vanes or rotors or to ex-ternal power sources apart from the wind. Another problem with these types of turbines is their tendency to accelerate, once rotating at an efficient rate, to a dangerous rotational velocity when the wind becomes excessive.
I have found that these disadvantages may be overcome by providing a central spindle having radial arms with straigh-t, vertically disposed airfoil vanes mounted at the tips of these arms by means of pivots which maintain the vanes parallel to the spindle but allow the vane a rotational movemen-t on a vertical axis passing through these pivots. The airfoil vane is pivoted ~àt a point on its chord near its leading edge and counter balanced so that its mass is equal both fore and aft of the pivot. An adjustable elastic device positions -the vane so that its leading and trailing edges are equidistant from the spindle except when the wind causes the vane to deflect from this position. ~his oapacity of each airfoil blade to be deflected from its normally tangential position is essential to the aerodynamic design of this invention. It allows each blade to assume independently a position of balance between the deflecting ef~ect of -the wind and the tension of the elastic device, thus maintaining -the airfoil vane, at any 30- point on its rotation about the spindle axis, at an advantageous angle of attack, thereby maximizing the aerodynamic lift of each vane.
The resul-tant rotational vectors of this aerodynamic lift is -the 4~

~04~03~3 essential propelling ~orce of this invention. Furthermore, by varying the tension of the elastic device, thus altering the angle of attack assumed by the vanes, this turbine can be adjusted to operate at optimum efficiency for any chosen wind speed, this e~ficiency decreasing at wind speeds both below and above that chosen.
It is therefore a feature of this invention to provide a wind turbine which will begin to revolve and accelerate to an efficient velocity without requiring the assistance of power sources other that the wind or the addition of vanes or rotors which are unrelated 10 -to the overall aerodynamic design of the turbine.
It is ano-ther fea-ture of this invention to provide a wind turbine which can be adjusted to operate efficiently at a chosen wind speed.
I-t is yet another feature of this invention to provide a wind turbine whose efficiency declines when the wind speed exceeds that for which the turbine has been adjusted.
In drawings which illustrate embodiments of the invention, Figure 1 is a top plan view of one embodiment, Figure 2 is an elevation o~ the embodiment, 20_ Figure 3 and 4 are top plan views of a section of a lower radial arm near the point where it coacts with an airfoil~vane.
Referring to Figure 1 and 2 there is shown a central spindle 1 mounted by means o~ suitable bearings on a -fixed axle 2. The spindle 1 is appropria-tely shaped to receive and hold ~irm the radial arms 3. The vertical airfoil vanes are shown in their tangential position with attached counterweights ~, the elastic tensioning device, in this case cornprising a lever 6, rigidly attached to the airfoil vane on the inside face, a spring 7 conn-ecting the tip of the lever 6 to an anchor 8 on the radial arm 3.
30--_The purpose of this elastic device 6,7, and 8 is to position the airfoil vane 4 to the radial arm 3.
Referring to Figures 3 and 4, there is shown an airfoil vane 4 attached by a pivot 9 to a lower radial arm 3. Figure 3 shows 104S~38 an angle of deflection from the tangential position a vane 4 may assume on the windward side of its revolution about the spindle axle 2. Figure 4 shows an angle of deflection it may assume on the leeward. In both figures the vane 4 is assumed to be moving in a clockwise direction around the spindle axle 2 as viewed from above.
Both Figures 3 and 4 show the attitude assumed by the elastic de--vice 6,7, and 8 and the extension of the spring 7. It is clear from Figures 3 and 4 how the tension of spring 7 opposes the ten-dency of the wind to deflect the vane 4 from its tangential position.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE

PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS

1. An apparatus for extracting energy from a moving fluid, comprising a number of airfoils, a said airfoil having a straight leading edge and a straight, parallel trailing edge, said airfoil being symmetrical about a plane intersecting said edges, said airfoil being attached to the ends of a respective pair of radially disposed support members extending from a central spindle, said spindle axis being disposed parallel to said edges, said attachment being by means of a pair of coaxial pivots, said pivots allowing for a free pivoting of said airfoil about a pivot axis disposed parallel to said edges and forward of the aerodynamic center of lift of said airfoil, a counterweight appended to said airfoil, causing the combined mass of said counterweight and said airfoil to be equally distributed about said pivot axis, an elastic member connecting said airfoil to a respective said radially disposed support member, said elastic member positioning said airfoil about said pivot axis such that said airfoil edges are equidistant from said spindle axis when said fluid is at rest, said elastic member allowing for a predetermined pivoting of said airfoil under the force of said moving fluid, said spindle axis being fixed perpendicular to the direction of said moving fluid, said apparatus revolving about said spindle axis at a predetermined rate under the force of said moving fluid.