Horizontal Windmill

Abstract

Multiple radial beams extend horizontally for rotation about a vertical axis, and support at their outboard ends vertical, aerodynamic sails which pivot about vertical axes. Cams and cam followers pivot trim tabs at the downstream ends of the sails which shifts the main body of the sail to produce additive lift forces for sustained rotation in a desired direction, while weather cocking the sail as the arms move to right angle positions with respect to the wind.

Description

BACKGROUND OF THE INVENTION

1. FIELD OF THE INVENTION

This invention relates to windmills and more particularly to a windmill whose driving surfaces are fully controllable with respect to the wind direction.

2. DESCRIPTION OF THE PRIOR ART

Most windmills in use during the past centuries have employed a horizontal rotational axis with the vanes of the windmill being radially disposed to that axis which requires extensive horizontal support and results in force imbalance acting on the rotary vane array.

SUMMARY OF THE INVENTION

The present invention concerns the type of windmill which the sails are vertically oriented, are of aerodynamic cross section similar to the vertical stabilizers in airplane tail sections, and are mounted for pivoting about a vertical axis at the outboard ends of respective beams which form a radial array, are circumferentially spaced equally and are mounted for rotation about a vertical axis at the beam intersection point. The improvement resides in automatic means to set the angle of attack of the sails and to control the speed. Shut-off is accomplished by neutralizing the control surfaces and letting the sails weather cock or align themselves into the wind for minimum drag.

It is, therefore, a primary object of the invention to provide a windmill which os fully controllable within a wide range of wind speed and having configuration involving a vertical output shaft so that any machinery driven by the shaft may be placed out of the slipstream of the wind passing over the sails and protected from the weather.

A further object of the present invention is to provide a windmill that is both economical to build and rugged in its resistance to the elements. This results in low initial and minimum maintenance costs, and prevents the windmill from being blown away or heavily damaged by periodic storms which pass its way.

A further object of this invention is to provide sails to a windmill that offer a minimum resistance to the winds along its path as compared to the useful torque produced and sails which generate forces which are added to each other and one wherein the forces being exerted by the sails through the respective cross arms to the central take-off shaft balance out each other, do not overload the tower supporting the same, and permit each of the sails to provide additive torque for rotation of the shaft in a given direction.

A further object of this invention is to provide a windmill whose sails have low resistance to the wind when it is shut down or running at light load in a relatively high wind.

A further object of this invention is to provide a windmill of this type which has low inertia to accommodate changes both to alterations in directions of the wind and in velocity of the same, while exposing as little area as possible to the vertical components of wind gusts.

It is further object of the present invention to employ a design which is esthetically appealing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of one embodiment of the vertical sail, windmill of the present invention.

FIG. 2 is a top plan view of the windmill of FIG. 1.

FIG. 3a is a top plan view, partially in section, of a portion of one beam of the windmill of FIG. 2 and the sail carried thereby, with the lower sail pointing toward the pivot axis of the windmill, with the control arm in the high eccentric position relative to the sail support shaft axis.

FIG. 3b is a similar view to that of FIG, 3a, with the cam shifted to the low eccentric position.

FIG. 3c is a similar view to that of FIGS. 3a and 3b with the cam shifted to full eccentric position opposite to that of FIG. 3a.

FIG. 4 is a side view of the windmill showing the actuating means for the sail assemblies.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The windmill indicated generally at 10 comprises, in one form, a tower 12 formed by four upwardly and inwardly inclined posts 14 which fixedly and commonly support at their upper ends a collar assembly 16 which rotatably supports a vertical, power take-off shaft 18 which has coupled thereto at its upper end a cross arm mounting hub 20. Extending outwardly from the hub 20 are a plurality of horizontal beams 24, preferably, in even number, spaced equi-distantly in a circumferential direction with respect to each other and rotating within a horizontal plane. The beams 24 rotate with the hub 20 and with the power take-off shaft 18. At the outer end of each beam 24, there is provided a vertical pivot shaft 26 which is fitted into a guide and thrust bearing (not shown) located in the beam, it being necessary for the shaft 26 to be free to rotate but being fixed vertically, that is, it may not move up and down with respect to beam 24. The shafts 26 pivotably support sail assemblies 28a, 28b, 28c and 28d on respective beams. For each sail assembly such as sail assembly 28a, FIG. 4, there is provided an upper sail 30 and a lower sail 32 which are fixed to the shaft 26 and both rotate with that shaft. Both sails are aerodynamically configured, that is, they are streamlined and are shaped so as to provide aerodynamic lift depending upon their angle of attack with respect to the wind. In cross section, they are quite similar in configuration to that of a conventional aircraft wing. The pivot shaft 26 supports the upper sail 30 and the lower sail 32 such that the center of lift of each sail 30 and 32 is slightly behind the shaft 26, relative to the direction from which the wind emanates. With the pivot axis slightly in front of the center of lift, the upper sail 30 and lower sail 32 will naturally try to weather cock or align themselves with the wind at its minimum lift and drag angle.

With respect to the lower sail 32, this sail is provided with a trim tab 34 coupled to the lower sail 32 by way of a hinge joint, formed by a hinge pivot pin 36 at the trailing edge of the same, the trim tab 34 acting to form a control surface, that is, a means for shifting the sail assembly about the pivot axis as defined by shaft 26 relative to the wind direction depending upon which side of the longitudinal axis of the sail assembly, the trim tab 34 is displaced.

By further reference to FIG. 2, the improvement provided by the windmill of the present invention resides in the means for automatically displacing the trim tabs 34 of respective sail assemblies 28a, 28b, 28c and 28d as the sail assemblies cause beams 24 to rotate in unison about the pivot axis as defined by power take-off shaft 18. As is seen by arrow 38, continuous counterclockwise rotation occurs by controlling the position of the trim tabs 34. When the beams 24 are generally in alignment with the wind indicated by the three arrows 40, the sails and the trim tabs of those sail assemblies are moved to non-aligned positions, while when the beams 24 are generally at right angles to the direction of the wind, those sail assemblies are permitted to weather cock, that is, to move to a position of alignment with the wind. Thus, when the trim tab 34 is pivoted to the right of the longitudinal axis of downwind sail assembly 28c, the trim tab 34 develops a trim lift to the left indicated by arrow 42, this shifts the trailing edge of the sail to the left and air flow over the main body of the sail which is of aerodynamic configuration, now produces a much larger lift 44 of the sail assembly 28c to right and tends to rotate the beam to the right or counterclockwise about the pivot axis of shaft 18 as viewed from above as identified by arrows 38. With respect to sail assembly 28d, since its beam 24 is at right angles to the direction of the wind, the sail assembly 28d at the outer end of that arm is permitted to remain in neutral or to weather cock into the wind and produce minimum drag, since they are at zero advantage with respect to the driving of the windmill. Further, as indicated in FIG. 2, the upwind sail assembly 28a has its trim tab 34 pivoted to the left, producing a trim lift to the right as indicated by arrow 46, the upper and lower sails 30 and 32 pivot such that the trailing edge of the sail moves to the right and the leading edge to the left and the air flow over the main body of the sail assembly produces much larger lift to the left as indicated by arrow 48 tending also to rotate its support beam 24 counterclockwise about the pivot axis of shaft 18. Thus, the driving force exerted by the wind on sail assembly 28a is additive to that force produced on sail assembly 28c. Meanwhile, at this point in the cycle, the sail assembly 28b weather cocks in the identical manner to sail assembly 28d for minimum drag.

This type of interaction with the wind results in a very high torque being produced as compared to the drag and weight which would load the supports in comparison to the windmill of the known prior art.

The trim tabs 34 are automatically controlled in response to the angular position of the arms supporting the respective sail assemblies as derived from a cam and follower arrangement associated with the beams 24 and thier sail assemblies. Reference to FIG. 3a, 3b and FIG. 4 illustrate the make-up of the control mechanism and its nature of operation. For each sail assembly, a circular cam 50 is provided with an elongated slot or hole 52, through which passes the pivot shaft 26 of the sail assembly which of course is pivotably mounted to the outer end of a given beam 24. The circular cam 50 may be conveniently mounted between the beam 24 and the lower sail 32 as shown in FIG. 4 and the hole 52 is elongated in the direction of the longitudinal axis of the beam 24 such that the circular cam 50 shifts longitudinally relative to the axis of the beam 24 under control of a cam shift control rod 54. The control rod 54, in each case, is pivotably coupled to the cam 50 and extends radially inwardly toward the hub 20. The outer end of the control rod 54 is pivoted at 56 to the upper face of the circular cam 50. The inner end of the control rod 54 is pivotably coupled to one end of connecting rod 60 at 58 and the control rod 54 is spring biased by coil spring 62 having one end fixed to the pivot connection between connecting rod 60 and the inner end of rod 54 and the other end secured by way of mounting screw 64 to the reduced diameter portion 66 of hub 20. A cam follower 68 in the form of an oblong circle having a minor internal diameter equal to the diameter of the circular cam 50 and a major internal diameter which is at least equal to the diameter of the circular cam 50 plus the length of the longitudinal elongated slot 52 within that cam minus the diameter of the shaft 26. The cam follower surrounds the cam, and has extending longitudinally therefrom along the minor axis, a connecting rod 70, including a straight portion which is slidably restrained by a pair of inverted U-shaped clamps 72 mounted to the upper face 74 of the lower sail 32. The connecting rod 70 terminates in a laterally offset portion 76 which is pin coupled to bell crank 78 by way of a pivot pin 80. The inner end of the bell crank 78 is fixed to trim tab 34 at a right angle to the major axis of said trim tab at a point near to the pivot pin 36, such that axial shifting of the connecting rod 70 affects shifting of the trim tab 34 from a position to the left of the longitudinal axis as seen from the trailing end of sail assembly, FIG. 3a; through a position where the trim tab 34 is in axial alignment with the sails 30 and 32, as when the effective cam surfaces are at equal distances from the center of shaft 26, and as shown in FIG. 3b; to the position as shown in FIG. 3c when the connection rod 70 is at its most outward position and the sail is pointed away from the center of the rotating assembly. The shifting of cam 50 relative to the shaft 26 such that the shaft 26 occupies the proximate end of the elongated hole 52 rather than the distal end, causes cam follower 68 to shift along with the connecting rod 70 in longitudinal direction, to a position where its cam surfaces are concentric with shaft 26 and the trim tab 34 will be in neutral position with respect to the sail 32 at all positions of the sail with respect to the supporting beam 29. It is important only to realize that the cam 50 may be shifted with respect to shaft 26 such that the cam occupies a position coaxial therewith with the shaft centered within the elongated slot 52, or position in which the shaft is either at the proximate or distal end of the slot or hole with respect to the pivot axis at the center of the windmill.

The mechanism for achieving shifting of rods 54 comprises upright pins 84 which are fixed at their bottom ends to lower axially movable collar 86 slidably positioned on hub 20. The pins 84 pass through openings of slightly larger diameter within an upper fixed collar 88. The pins 84 are pivotably coupled to respective connecting rods 60 at pivot pin connection 90. Thus, by shifting collar 86 axially with respect to collar 88, the rods 54 are moved outwardly against the bias of springs 62 or moved inwradly to shift the cams and force the cam followers to follow to pivot the trim tabs to the desired position. Once the control rods 54 are set, the trim tabs 34 will take the desired position automatically as the hub rotates, that is, the cams by be set such that the trim tab 34 of a given sail assembly is inclined to the right as the sail is in its downward position as is sail assembly 28c, and in general alignment with the direction of the wind. The opposite is true when a sail assembly occupies the position of sail assembly 28a in its full upwind position and in general alignment therewith.

Since the sails pivot along with vertical shaft 26 as the beams rotate, the cam follower rotates about the cam 50. When the beams reach positions generally transverse to the axis of the wind, the major axis of the cam permits the bell crank to move such that the trim tabs 34 occupy in line or feathered position with the wind moving along both sides of the sail assembly, the trim tabs 34 are at neutral positions and the sail assemblies weather cock. It may be seen that axially sliding or moving collar 86 up or down relative to fixed collar 88 causes identical shifting axially of control rods 54 and equal positioning of the cams 50 relative to their shafts 26 passing therethrough.

To summarize, with the control rods 54 preset, such that the cam is at its radially inboard position with reference to the cam follower 68, the spring 62 pulls the connecting rod 70 in on the cam and working through the bell crank 78 will displace the trim tab 34 to the right of the longitudinal axis looking in the direction of the wind. However, this same sail assembly, when in the upwind position, will be facing radially outward on its beam 24 corresponding to the position of sail assembly 28a, and the cam follower 68 will be on the high part of the cam 50 and will displace the trim tab 34 to the left as is required for cumulative counterclockwise rotation. By putting the bell cranks 70 on the other side of the beam axis, the action of the cam and cam follower and the connecting rods 70 would effect reverse rotation to the trim tabs for the sail assemblies at upwind and downwind positions and reverse the direction of rotation of the windmill.

The sails to the left and the right of the wind are aligned across the beam having their cam followers at the normal height of the cam and the trim tabs will automatically move to neutral position.

The cams 50 and the operating rods 70 are made of heavy material and the rotation of the beams 24 produce centrifugal forces tending to stretch the springs 62, allowing the cams 50 to move towards their most concentric position relative shaft 26, that is, the shaft will be centered relative to the elongated hole with the cam follower following the movement of the cam. In the concentric position, the trim tabs 34 are at neutral at all positions around the shaft and the windmill will be shut off. When this action results from centrifugal force acting on the springs 62, the windmill may not be completely shut off, but will reducce its speed to that which will produce the torque necessary to sustain a relatively constant speed. Thus, the present invention uses the springs 62 to control the shifting of the control rod and the position of the cams 50 relative to the shafts 26 passing therethrough to insure reduction in effort and a limit on the speed to compensate for changes in the force of the wind over a wide range of wind conditions.

Additionally, the windmill 10 may be shut down by outside action either manually, by means of the movement of collar 86 with respect to collar 88 as shown by arrow 100 or by automatic controls (not shown). Shut-off collar 86 in FIG. 4 is moved upward by any convenient means as by manual force application, forcing the pins 84 to shift upward and moving connecting rods 60 and moving in turn the operating rods 54 to shift the cams to their neutral position such that the trim tabs are positioned in alignment with the sails 30 and 32 of each sail assembly. With the sails weather cocking, no torque is produced and minimum drag is experienced by the windmill, thus preventing damage to the windmill in the case of storms with their resultant high velocity winds.

While the invention has been particularly shown and described with reference to a preferred embodiment therof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

Claims

What is claimed is:

1. In combination; a windmill comprising;

a plurality of vertical aerodynamic sail assemblies,

sail supporting means for maintaining said sail assemblies in positions for pivoting about a vertical pivot axis for each assembly with the center of lift of each sail being slightly behind the vertical pivot axis thereof and including at least one vertical aerodynamic sail in each assembly,

means permitting said sail assemblies to move in a closed circular path,

means for additively applying the torque output of the wind acting on the sails of said sail assemblies to provide output torque for said windmill,

a trim tab pivotably mounted to said at least one sail of each sail assembly such that the trim tab is disposed downwind from the trailing edge of said one sail,

control means responsive to movement of said sail assemblies about said closed circle for automatically pivoting said trim tabs to inclined positions relative to the longitudinal axis of the sails when said sail supporting means is rotated such that the sail axis, the circular path axis and the wind direction are substantially in line such that these sails provide additive forces tending to rotate said sail supporting means in the same direction, and for maintaining the sail assemblies that are generally at right angles to the circular path axis and the wind direction in weather cocked position;

whereby, said sail assemblies provide minimum drag in comparison with their useful additive torque output.

2. The windmill as claimed in claim 1, wherein said support means comprises a vertically supported hub mounted for rotation about its axis, said plurality of sail assemblies are mounted at circumferentially spaced positions radially outward from said hub.

3. The windmill as claimed in claim 2, wherein said trim tab control means comprises a cam operatively carried by said sail supporting means at each sail assembly position and a cam follower carried by each sail assembly, operatively positioned with respect to said cam and operatively coupled to said trim tab, such that upon rotation of said hub and said sail supporting means, said sail assemblies pivot to maintain positions in general alignment with the wind, and said cam followers in following the profile of the cam pivot said trim tabs to given inclined positions relative to the longitudinal axis of the sail assemblies when the sail assembly pivot and the hub of the sail supporting means are generally in line with the wind.

4. The windmill as claimed in claim 3, wherein; each cam is circular and includes an elongated slot intersecting its center, said sail is pivotably mounted to said sail supporting means by means of a shaft passing through the elongated slot and said windmill includes means carried by said sail supporting means for maintaining the elongation parallel to the radius of said support such that the rotation of said hub causes said cam follower to rotate about the sail pivot shaft such that said cam is eccentric to said cam follower when said sail axis, the hub axis and the wind direction are generally in line, with the sail assembly in a extreme downwind or extreme upwind position.

5. The windmill as claimed in claim 4, wherein said means for preventing rotation of said cam comprises a control rod mounted at one end to said cam parallel to the elongated hole within said cam, and extending radially inwardly from said cam towards said hub, and a biasing means yielding holding said control rod and said cam toward the radially proximate end of said elongated slot, and said biasing means allowing said control rod to yield to centrifugal force to limit the upper speed of the windmill to a given value.

6. The windmill as claimed in claim 5, further comprising: an upper collar fixed to said hub and rotatable therewith, a lower collar coaxially mounted beneath said upper collar on said hub and axially slidable toward and away from said upper collar, holes carried at circumferentially spaced positions within said upper collar corresponding to said control rods, pins fixed to and extending upwardly from said lower collar at circumferentially spaced positions corresponding to said holes, and received by the holes within said upper collar and connecting rods pivoted at one end to the ends of said pins projecting through said upper collar, and to the inboard ends of said control rod; whereby, axial shifting of said lower collar with respect to said upper collar shifts the cams relative to the sail pivot shafts to position the cams concentric to position either concentric with or eccentric to the sail pivot shafts.