Field of the Invention

[0001] The present invention relates to wind rotors and is particularly concerned with drag type wind rotors. Background of the Invention

[0002] When a rotor is designed as a "drag" device to operate behind the wind, then the orientation (i.e, angle to the wind), the speed of the wind and the shape of the wind rotor mean that the drag coefficient (i.e. a dimensionless quantity which is used to quantify the drag or resistance of an object in a fluid environment such as air or water) becomes a major factor and can vary from 0.01 up to 2.5. The following are sample drag coefficients for some well known structures.

[0003] Conversely to "lift type" rotors, tile maximum efficiency of a drag rotor is obtained when the drag coefficient is as large as possible. With a drag type wind rotor, using a vertical axis maximizes the drag coefficient and the conversion of the wind force as a torque results in the direct application of the drag equation: F _D = - pu ² C _D A, where:

FD is the force of drag, which is by definition the force component in the direction of the flow velocity;

p is the mass density of the fluid;

u is the velocity of the object relative to the fluid;

A is the reference area; and

CD is the drag coefficient— a dimensionless constant.

[0004] When perpendicular to the wind, certain shapes produce higher drag coefficients than others, see Fig. 1:

[0005] Wind Rotors function as transformers of the kinetic wind power into rotational motion and may have horizontal or vertical axes. Drag Rotors generating up to 1 mW, not having to convert perpendicularly the direction of the wind flow to generate a rotary motion, are superior as they may collect about twice the energy contained in the wind than HAWT (Horizontal Axis Wind Turbine) using a propeller. Also, they are able to work at slower speeds.

[0006] With conventional three blade wind rotors (called 'Lift Type' Rotors), the propellers use the "lift" effect to make the blades turn, and therefore only the "induced lift drag" may improve the rendering ratio of the device, while any other form of drag impedes performance and should be reduced as much as possible, (see Fig. 2)

[0007] Furthermore, conventional three blade wind rotors face additional problems because they generally have a horizontal axis and being lift type, they deflect the wind, even before the wind reaches the totor plane, (see Fig. 3)

[0008] Therefore they are inefficient in capturing the energy in the wind, due to: • several laws of physics (i.e. Betz law which reduces their capacity to collect the power of the wind at only 16/27); the fact they convert the wind energy into a perpendicularly rotary motion, which divides the collectable results by one half (See Fig. 4); and their design and weight means that they do not even start to turn until wind speeds of 4.5 to 5 meters per second (m/s), and do not produce any significant power until wind speeds of 8 to 12 m/s are raised, and by design of conventional wind technology do not capture additional, usable wind energy with winds over 12.5 m/s.

[0009] Fig. 5 illustrates a Darrieus model, which is a vertical axis wind tutbine (VAWT). [0010] The Savonius wind rotors, illustrated in Fig, 6 are a type of VAWT, used for converting the power of the wind into torque on a vertical rotating shaft. Aerodynamically, they are also drag-type devices, consisting of two or three scoops.

[0011] Fig. 7 shows a plan view a Savonius Rotor from above, a two-scoop machine would look like an "S" shape in cross section. Because of the curvature, the scoops experience less drag when moving against the wind (i.e. drag coefficient Cd2 = 1.2) than when moving with the wind (i.e, drag coefficient CdI*= 2.3). The differential drag being positive, it causes Savonius turbines to spin. Because they are limited by such differential, Savonius turbines extract less of the wind's power than other similarly-sized lift-type turbines but work better with low wind speeds, [0012] Systems and methods disclosed herein provide a wind rotor to obviate or mitigate at least some of the aforementioned disadvantages.

Summary of the Invention

[0013] An object of the present invention is to provide an improved wind rotor.

[0014] In accordance with an aspect of the present invention there is provided a wind rotor comprising a frame, a first drag rotor rotatably coupled to the frame at a first axis, a second drag rotor rotatably coupled to the frame at a second axis, and a deflector positioned between the first and second drag rotors for deflecting wind to a portion of the first and second rotors, each drag rotor having a hub, a stator spaced from the hub and a plurality of sails coupled to the hub on a first edge and slidably coupled to the stator at a second edge. {0015] In accordance with an aspect of the present invention there is provided a wind rotor comprising a frame, a drag rotor rotatably coupled to the frame at an axis and a deflector positioned adjacent the drag rotor for deflecting wind to a portion thereof, the drag rotor having a hub, a stator spaced from the hub and a plurality of sails coupled to the hub on a first edge and slidably coupled to the stator at a second edge. Brief Description of the Drawings

[0016] The present invention will be further understood from the following detailed description with reference to the drawings in which:

Fig. 1 illustrates wind eddies and turbulent flow created by various shaped bodies;

Fig. 2 illustrates the forces acting on an airfoil;

Fig, 3 illustrates the effect a propeller type wind turbine has on air velocity;

Fig. 4 illustrates the effect a propeller type wind turbine has on air flow;

Fig. 5 illustrates a known Darrieus model wind turbine;

Fig. 6 illustrates a known Savonius wind rotor;

Fig. 7 shows a plan view of a Savonius rotor;

Fig. 8 illustrates, in a perspective view, a wind rotor in accordance with an embodiment of the present invention;

Fig.9a illustrates, in a plan view, the wind rotor of Fig. 8;

Fig. 9b illustrates, in a front elevation view, the wind rotor of Fig. 8;

Figs. 10 to 14 illustrate plan views showing the operation of the wind rotor of Fig. 8;

Fig, 15a and 15b illustrate, in an elevation view, sails of the wind rotor of Fig. 8;

Fig. 16 illustrates, in a perspective view, a portion of the frame of the wind rotor of Fig. 8;

Fig. 17 illustrates, in a perspective view, the frame of the wind rotor of Fig, 8;

Fig. 18 illustrates, in a perspective view, a sail frame of the wind rotor of Fig. 8;

Fig. 19 illustrates, in a three dimensional rendering, a wind rotor in accordance with an embodiment of the present invention; Fig. 20 graphically illustrates the efficiency of the wind rotor of Fig. 8 under various conditions; and

Fig. 21 illustrates a roof edge installation of wind rotors in accordance with embodiments of the present invention.

Detailed Description of the Preferred Embodiment

[0017] Referring to Fig. 8 there is illustrated in a perspective view, a wind rotor in accordance willi an embodiment of the present invention, A drag rotor may have either a horizontal or vertical shaft, however a frame based on a vertical double drag model (coupling two vertical axis rotors) is more particularly described hereunder. The wind rotor 80 includes a frame 82 upon which are rotatably mounted two drag type rotors 84, each having a cylindrical core 86 and a plurality of sails 88 attached to the cylindrical hub 86. The wind rotor 80 also includes stators 90 in the form of hoops attached to the frame 82 above and below each rotor 80 for providing a track for the outer edge of the sails, A deflector 92 having two planar surfaces forming a V-shape is mounted on the frame to block the inner sails of the adjacent rotors 84, The frame 82 is mounted on a main mast 94 for pivotal movement and in addition is supported by two secondary masts % which are wheeled for movement on a flat surface such as a flat roof.

[0018] According to embodiments of the present invention specially designed "Double Drag Rotors" whose sails are made of lighter and different materials (e.g. Dacron, Kevlar or Mylar) are provided that optimize torque and operate at much lower wind speeds than other rotors. The design improves performance by exploiting torque rather than velocity, while based on drag factors rather than lift effect.

[0019] With this design the creation of torque by kinetic power is more important than the rotary speed transferred from the wind rotor to a downstream engine shaft. By contrast, with conventional horizontal wind turbines (or Darrieus turbines), the velocity that the wind may give to the propellers is more important. [0020] Conceptually, any design and type of rotor may be used as long as it produces a torque to turn a shaft connected to the rotor, so that the shaft actuates the downstream application (e.g. high torque with slow rotational speed rather than smaller torque with high rotary motion, as with Savonius Rotors). [0021] In aerodynamics, the "Lift" force is defined to be the component of the force exerted on a body by a fluid flowing past its surface, which is perpendicular to the oncoming flow direction. With conventional wind rotors, made of propellers, the blades' airfoil is a streamlined shape that is capable of generating significantly more lift than drag, This contrasts with "Drag" (sometimes called air resistance or fluid resistance) which refers to forces that oppose the relative motion of an object through a fluid (a liquid or gas, including air). Drag forces act in a direction opposite to the oncoming flow velocity. Unlike other resistive forces such as dry friction, which is nearly independent of velocity, drag forces depend only on wind velocity.

[0022] In aerodynamics, two types of drag must be considered for wind rotors:

• "lift-induced drag", which is a drag force that occurs whenever a moving object redirects the airflow coming at it; and

"form drag", which arises because of the form of the object (see Fig. 1),

[0023] Referring to Fig. 9a there is illustrated in a plan view, the wind rotor of Fig. 8. Fig. 9a shows the double drag rotor 80 with optional hydraulic generators (pumps) 100 coupled to each of the hubs 86 of rotors 84. This would be used in an application where the wind power was used to pump water. Fig. 9b illustrates a front elevation view the wind rotor of Fig, 9a.

[0024] Referring to Figs. 10 to 14 there is illustrated in a plan view, the operation of the wind rotor of Fig. 8. The preferred embodiment of the drag rotor 80 uses sails shaped like an arc of cylinder or using a spiral spine, with an off-centered axis of the central rotor hub 86 versus the external circle. One side of the sail is guided alongside the external circle of the statoτ 90 while the other side swivels while turning with the central rotor hub 86 (See Fig. 11).

[0025] In operation, as shown in Fig. 12, deflectors 92 direct wind toward outer sails 88a and 88b, while blocking inner sails 88c and 88d. Adjusting the offset of the hub 86 along line 102 increases or decreases the amount of sail exposed for the outer sails with the converse effect on the inner sails, as shown in see Figs. 10 and 11 , This "off-centered" motion enables each sail Io turn separately and differently from the others according to its position with the rotor's shaft.

[0026] The drag rotors 82 use swϊveling and sliding rotary curved sails 88 instead of blades, and therefore work more like boat-sails or Savonius scoops than the wings or blade propellers of the conventional wind industry, which are based principally on the lift effect Drag rotors are 'drag devices' because both types of drag are exploited when the wind hits the sails while passing through the two rotors (i.e. form drag and induced lift drag) to convert as torque a maximum of the collected energy which results from the volume and speed of the wind stream. (See Fig, 10)

The frame and positioning of the sails are designed to optimize exploitation of these drag phenomena, which include but are not limited to;

• Coupling two rotors, assembled together in opposite direction for limiting negative drag impediments (See Fig. 12)

Using so-called "double drag" sails (arc of cylinder or spiral spine) because their shape enables both 'form drag' and 'induced BfI drag' to better increase the quantity of energy collected from the wind stream velocity. (See Fig. 11 )

• Off-centering the axle of the rotors to enable the angle of the sails versus the wind stream to vary while the rotor turns (See Fig. 13), enhancing the sail efficiency to the drag when positioned to work as positive drag sail on the windward side and reversely reducing the drag effect, on the leeward side and therefore • The sails 88 are sliding and guided alongside the stator 90 while they turn around the rotor axle where they are swiveh ^' ng, so that they offer as much as possible a better induced downwash angle and may work better regardless of their position,

• Because of the angle formed by the sail 88 versus the rotor hub 86, the push force of the wind becomes effective only when the sail retrieves its position of "positive drag sail" and transmits the power collected from the wind to the rotor 84, (see Fig, 12) [0027] Using deflectors 92 enables protecting the sails from being submitted to negative drag (see Fig. 4), so that any negative drag is minimized almost to become insignificant. Because of the deflectors 92, the wind pushes on the sails (88a and 88b) only on the external half side of the rotor and there is almost no affect of the wind on the sails (88c and 88d) while turning around the rotor to come back to the front, where sails could be called "negative drag sails".

[0028] Also, because sails 88 are not rigid, but use material made of cloth like boat sails (including for example, Nylon, Mylar, Kevlar, Dacron or similar materials), and possibly battens (see Fig. 15a) that enables the installation of mechanisms for automatically reducing the sails surface in case of storms or very high winds, as shown Fig. 15b, This not only enables protecting the device from eventual damage, but facilitates the adaptation of the amount of power collected to the needs of the downstream equipment. This is possible either by adding a mechanism which enables dropping the sails or integrating rollers in the sails' frame (e.g. on the rotor's side). The system of rolling furlers should be preferred as it enables automatically to regulate the foil surface of the sail by comparison with the rotational speed of the rotor, while using springs on the stator side for keeping the sail open as much as needed. Doing so, the drag rotor 80 becomes a "variable turbine" which enables control of the volumes of water flow handled downstream without use of a gearbox and other τegulatory mechanisms, which generally result in major losses of energy inefficiencies.

(0029] As shown in Figs. 15a and 15b, the sails are terminated with slides or rollers 134, which may or may not have bearings and/or low-friction surfaces such as Teflon. These slides or rollers 134 mate with the rotor 82 and stator 90.

[0030] Referring to Fig. 16 there is illustrated in a perspective view a portion of the frame of the wind rotor of Fig 8. The frame portion 120 includes stators 90, a ring 122 for receiving the main mast 94 and bracing 124. Two such frame portions 120 are assembled into the complete frame 82 as shown in Fig. 17.

[0031] Referring to Fig. 17 there is illustrated in a perspective view, the frame of the wind rotor of Fig, 8. The complete frame 82 comprises two frame portions 120 joined by elongate spacers 130, main mast 94 and secondary masts 96. The frame 82 is mounted on three masts, thereby forming a tripod. The main mast 94 in front is dedicated to support the weight of the structure and to bring resistance to the frame for standing up. Also, as it may rotate, it enables the entire frame to turn around. The two other supports are made of the shafts, called secondary masts 96 of the drag rotor 80 and each is mounted on a wheel 132 (see Fig. 19). Because the rotors offer a resistance to the wind push, these secondary masts 96 automatically roll behind the main mast 94 to optimally orient the drag rotor to lace the wind. The counter-rotating rotors 84 beneficially cancel net torque that could skew the presentation of the drag rotor to the wind.

(0032] The rotor frame 82 generally is made of a tube. This enables capturing better the wind in the vanes that are formed with the sails, the space between two sails shaping a kind of a paddle. Otherwise, the rotor frame 82 may be made of two wheels fixed at the top and the bottom of the sails, In this model, the shape of the sails generally is simplified as a simple arc of cylinder as shown in Fig 18. However, here the sails do not create a closed space working like a paddle. Instead, the wind hitting the sails is redirected to the center of the Rotor and then hits the other sails, creating a "Savonius" effect. The advantages of either solution will be apparent to one with skill in the art upon examination of the requirements resulting from the wind conditions where the drag rotors should be installed,

[0033] Using two opposite rotors in a common frame enables significantly improving the reduction of negative drags. The pair of deflectors may work by redirecting on both directions all the wind which would affect "negative drag sails". This enables each rotor to capture one half of the overall foil surface, including the deflectors area.

[0034] Efficiency is improved when the drag differential of opposing sails of a rotor is the greatest possible. Therefore, different principles were applied when designing the Drag Rotor, with swiveling / sliding sails and deflectors:

Reducing the negative drag applicable to less than 1/8 of each rotor o by using deflectors to redirect part of the wind to the working airfoils o by reducing the airfoil and angle of the sails whose position would submit them to negative drag ^• Increasing the airfoil submitted to the "form drag" (i.e. the drag which arises because of the form of the object - CDf) o by grouping a maximum of working sails in the stream of the wind - CDi o by orientating the sails so that they are the most perpendicular to the wind direction ^• Developing the "induced lift drag" factor (i.e. drag force that occurs when an object redirects the airflow coming at it - CDi - See Fig. 14) o by organizing a depression area at the rear of the Drag Rotor where o the stream of air passing through the device, and so being slowed down, is submitted to a suction phenomenon (= induced lift drag) due to the suction generated by the wind deflected around the device.

^• Using torque as great as possible (see Fig. 17) o by using a design where dimensions of the frame are calculated to offer the best Rotor's diameter versus the height with the required foil surface. Also, making the frame wider than taller means that the Rotor will turn slower and may work with larger range of wind speed. o A slower rotation with a more important torque improves the possible transfer of energy to the Hydraulic Generator actuated by the Rotor (see Hydraulic Generator Patent, Canadian Patent Application Serial No. 2,677,002), especially when normal wind speed average to exploit is low.

[0035] Referring to Fig. 19 there is illustrated in a three dimensional rendering, a wind rotor in accordance with an embodiment of the present invention.

[0036] Referring to Fig, 20 there is graphically illustrated the efficiency of the wind rotor of Fig, 8 under various conditions.

[0037] Referring to Fig. 21 there is illustrated a roof edge installation of wind rotors in accordance with embodiments of the present invention, In this example, a single rotor design is used, with a horizontal axis, A single deflector is also used, to deflect wind that would otherwise be directed towards the negative side of the sails.

[0038] Installing Drag Rotors does not require any special infrastructure such as foundations, road constructions, telephone and cabling at the site or prior to transportation to the site as required by conventional wind turbines.

10039) Also, Drag Rotors more easily meet environmental regulations than conventional wind turbines and rotors.

[0040] Using a Drag Rotor optimizes the torque exploited by the downstream application and operates at much lower wind speeds than other rotors, [0041] The table below shows the power contained in the wind compared to its speed and the maximum recoverable power for conventional wind rotors and Savonius Rotors compared to the Drag Rotor:

[0042] The Kinetic Power in the wind for an airfoil A (in m2), with a wind speed u (in m/s) and a density p (in kg/m3) is given by:

Where p = ± 1.23 kg/m ³ at 15 ⁰ C and with atmospheric pressure of 1.0132 bar.

[0043] The maximum recoverable power for a conventional wind rotoτ (with propeller) is:

Where the Betz factor = 16/27, K represents the Rendering Ratio of the propeller's shape (considered here as 80%) and Cp = Efficiency Coefficient of the propeller < 0.5 JW = 0.« * 0.296 P _Kin

[0044] For Savonius rotors, considering the drag coefficient differential of a hollow semi- cylinder facing an opposite stream, an ideal rotor would recover;

Py _« = PKm * ΔC _D = 16/27 * (2.3 - 1 2) * P _Km

PM«* = 0.65 P _m [0045] Double Drag Rotors cumulate both 'form drag' and 'induced lift drag' coefficients for the airfoil facing the wind stream (which represents 2/3 of the area) and are reduced by 1/4 of the area submitted to a drag coefficient opposite the wind stream:

PH* = Pκ» * (Cpf+ C _D ) = {2/3 * 16/27 * (2.3 + 0.6) - 1/4 * 16/27 * 1.2} *P _Km Because the deflectors, which are part of the airfoil of Drag Rotors, are not exploited and part of the wind is therefore deflected outside the device before hitting the rotors, this phenomenon must be computed as reducing 10 - 15 % the maximum power that may be collected, i.e. PM.* = ± 0 ^, 8 Pκ,n [0046] By using a Drag Rotor:

the power collected from the wind per square meter of the Drag Rotor is greater than that collected per square meter of a conventional wind rotor;

the rendering ratio for wind power collection is over 80% compared to less than 30% with propellers of conventional wind turbine rotors;

the foil surface area of the drag rotor may be less than the rotor of a conventional wind turbine to collect the same amount of wind energy;

the overall height of the Drag Rotor can be lower and thereby easier to protect against storms;

- drag rotors can be lighter thereby enabling turning, initiating turning and creating the requisite torque at slower wind speeds than conventional wind rotors;

the drag rotor is less sensitive to potential turbulences due to surrounding terrain and wind shear (e.g. agricultural land with some houses and sheltering hedgerows with some 500 m intervals means that heights of only 10 meters above the ground are sufficient for a drag type collector, whereas heights of greater than 80 meters generally are required for conventional wind turbines); and

drag rotor produces less noise than conventional wind turbines and rotors.

10047] With drag rotors, it is the creation of torque by the kinetic power of the wind that is important, to be exploited as a power source, Drag rotors may be dimensioned specially to fit better with the average wind speed where they are installed: how slow are the regular winds, how wide the foil surface should be versus limiting the height (while using the same foil surface). This can increase the torque sufficiently for reduced winds and enable the shaft to receive enough force for actuating the downstream device at slow levels.

[0048] The drag rotor can be sized so that the present invention can achieve 100% power production, and therefore capacity utilization, at a larger range of wind speeds whereas conventional wind turbine rotors are sized to achieve about 40% power production, and therefore capacity utilization, at wind speeds of 12.5 m/s.

[0049] Reducing significantly the costs for building, installing and maintaining a wind rotor, represents a major objective of the invention: A) There are no particular needs for drag rotors to be made out of expensive special materials, like a matrix of GRP (glass fiber reinforced polyester) as used for conventional wind propellers, so manufacturing costs can be significantly lower.

B) The frame can be entirely made of hollowed bars in metal. C) Their design makes it easy to specifically size a wide range of power collection thereby meeting the needs of the individual customer

D) Drag Rotors also are less expensive and easier to build, to fix and to maintain:

π AU of the equipment for collecting wind power is installed on the ground rather than on the top of the tower, so the tower can be lighter and cost a lot less.

D Manufacture, installation and operation requires less skilled labor than conventional wind turbines

D Assembly can be made without heavy equipment and cranes which are very expensive, therefore making Drag Rotors easier to install almost everywhere

0 This also can reduce the time from manufacture to installation (e.g. 90 to 180 days compared to more than up to 2 years for conventional wind power)

U Maintenance costs, including refurbishment and major overhauls, are reduced, because of the ease of accessing the equipment and lack of sensitive equipment comprising a conventional wind turbine

π Production costs are reduced because performance (see above) is improved. [0050] Other systems, methods, features and advantages of the invention will be, or will become, apparent Io one with skill in the art upon examination of the following figures and detailed description, It is intended that all such additional systems, methods, features and advantages be included within the description, be within the scope of the invention, and be protected by the claims. |0051] While embodiments of the invention are intended to be used first as drag rotors to run a generator better to produce electricity, it is designed more generally as a wind collector where the kinetic force of the wind, being converted as torque, can actuate any engine that requires such torque rather than velocity, This means that drag rotors may replace other types of wind turbines or wind mills for a number of uses, including:

o reverse osmosis;

o sewage;

o draining or pumping;

o energy storage using elevated containers;

o powering tools and/or industrial facilities; and

o production of electricity.

[0052] Primarily, the embodiments of the present invention intend to improve collection of medium range wind energy of 10 kilo Watts (kW) to 1 mega Watt (mW), by proposing a genuine design of a wind rotor, the drag rotor 80 based on the usage of drag forces.

{00S3J For improving maximum efficiency the drag rotor is:

o exploiting

drag forces rather than lift effect

• torque rather than velocity

o replacing

• thrust on spinning angular blades of a propeller by thrust on perpendicular foil of sails

• tall heavy structure by lower extra light frame

o coupling two rotors within Ae same frame:

means that the deflectors are protecting sails from negative drag.

• enables the Double Drag Rotors to exploit 100% of the foil surface,

o automatically oriented to work "under the wind".

o enabling operation as a "variable displacement" device by varying the foil surface of the sails according to the needs, and also reducing significantly the risks of damage with storm conditions.

(0054] Drag rotors enable 100% of production efficiency within a range of wind speed of 2-3 meters/second up to 22 meters/second, which represents 80% of the energy contained in the wind, whereas conventional wind turbines can only produce 40% at 12.5 meters/second with a valuable production efficiency limited from 8 m/s to 14 m/s,

[0055] Reducing the costs for building, installing and maintaining of a wind collector represents another major objective of the present drag rotor. [0056] The present invention has been described with regard to one or more embodiments. However, it will be apparent to persons skilled in the art that a number of variations and modifications can be made without departing from the scope of the invention as defined in the claims. All citations are hereby incorporated by reference.