This invention relates to windmills.

Windmills can be constructed in various ways, for instance it is customary to use a wheel with radial angularly disposed blades on it operating about a horizontal axis and geared through suitable crank mechanism to the pump rod of for instance a bore or well pump.

It is also known to use windmills in which the blades operate about a vertical axis, in which case the blades are shaped so that they have a higher wind resistance when facing windward and a lesser wind resistance when returning into the wind.

Amongst this latter type are those devices which have sails positioned outwardly from a vertical shaft and carried on a frame and provided with mean ^' s whereby the sails are positioned to exert a driving force during part of the revolution and to feather during the remaining part of the revolution, and this type of windmill, like the normal windmills which operate about a horizontal axis, require a tail or mechanism to hold the sails correctly into their power position as well as their feathering position.

The present invention relates to a windmill of that type which operates about a vertical spindle and has outwardly projecting blades which are arranged in the nature of scoops so that when in one position in relation to the wind direction they offer a sub¬ stantial resitance and in the other opposite direction a lesser resistance whereby the blades rotate around the central axis by the differential wind pressure on the blades according to their position.

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Problems with this type of windmill in the past have been to achieve an effective type of blade which will give an efficient action, and a further problem has been to provide an effective drive to a pump rod from such windmills. It is an object of the present invention to provide an improved form of device in which previous disabilities will be overcome.

The windmill according to this invention comprises a member such as a vertical shaft adapted to be supported on a suitable tower and on this shaft is a rotatable frame which has projecting outwardly from it a series of spaced generally radially disposed blades shaped to have a greater wind resistance on one side than the other, characterised in that the blades are shaped as wind scoops but with at least one aperture through the wall of the scoop covered by a flap arranged to close the aperture when wind pressure is directed into the blade but to open the aperture when the scoop returns into the wind.

• When used for pumping water a cam on the rotatable frame reciprocates a water-transmitting follower connected to the pump rod.

^* In order however that the invention may be fully understood an embodiment thereof will now be described with reference to the accompanying drawings in which:

FIG. 1 is a part sectional front elevation of the windmill as applied to actuate a pump rod, omitting the forwardly projecting blades,

FIG. 2 is a plane of same.

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FIG. 3 is an enlarged sectional elevation of the- head showing one blade and the cam which actuates the pump rod through a follower arranged in the form of a bell-crank,

FIG. 4 is a section through the cam and supporting shaft for the head as on line 4-4 of FIG. 3, and

FIGS. 5 and 6 are respectively sections on a blade on line 5-5 of FIG. _. 3, FIG. 5 showing the blade when its hollow is directed into the wind with the flap closing the aperture, FIG. 6 showing the blade when presenting its back to the wind with the flap open.

The windmill as illustrated comprises a vertical shaft 1 mounted on a stub tower 2 and onto the shaft 1 of the tower is sl ^' id a spacer 3 which locates a thrust bearing 4 at the lower end of the spacer, and a normal bearing 5 at the top of the spacer, these bearings supporting a rotatable tubular frame 6 which extends downwardly and to the lower part of which a cam 7 is fitted, the tubular frame 6 having on it a series of flanges 8 to which blades 9 which form the power means of the windmill are attached by means of stub shafts 10 engaged in sockets 11 formed in the flanges, to project outwardly from the flanges ^" 8.

The blades 9 themselves are in the form of scoops and in the form shown are arranged in three vertical rows, but the number of rows may be varied depending on the number and position of the blades to be used. By having a bore on each flange, which bores 12 engage the tubular frame 6, the number of flanges

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and hence the number of rows in which blades are positioned can be varied, as can their vertical separation as the bores 12 can be locked to the tubular frame at different spacings.

The blades are provided with apertures 14 over which are placed flaps 15 which are so arranged that the flaps shut when the blades move with the wind and open when they move against the wind, the purpose of this being to reduce drag and ensure more efficient operation.

It should be appreciated that a blade in the form of a scoop, while absorbing considerable power from the wind when it faces windward, still has considerable resistance when the blade is being returned against the wind during a cycle, the resistance of course being reduced by the curvature of the blade when it is in scoop form. The blades preferably taper to a larger width outwardly and have the aperture toward the outer end of the blades.

The purpose of the flaps, which open when the blades are returning against the wind, is to allow air flow into the inwardly dished parts of the scoops to counteract vortex formation which otherwise takes place behind the blades as they are returning into the wind. I have found that by using this construction a much greater amount of power is extracted from the wind than was possible with blades used heretofore. The wind flow is shown by full-line arrows in FIGS. 5 and 6, the dotted-line arrows showing direction of travel, in relation to the wind, of the scoop-shaped blades.

In this specification the expression "scoop-shaped" is defined as having a hollow or concave surface

on one side and a convex or medially outwardly curved surface on the other side.

The blades are staggered upwardly in rows to ensure that they present the best arrangement to achieve maximum drive, and it will be noted that the upper and lower rows are angled to prevent shielding of blades.

It should be understood however that the number of blades in a row, and the number of rows, and the vertical spacing of the rows, can be varied, and by using a rotational tubular frame 6 as illustrated the flanges 8 and the number ^' of flanges used can readily be selected to suit any particular condition and a windmill of the present invention is thus flexible and can be added to or blades or rows removed to suit power requirements.

The cam at the base of the tubular frame 6 can be of any required form and can be shaped to ensure that the power is directly applied to the pump rod 17, the cam in the illustrated embodiment being in the form of a channel which is off-centre in relation to the axis of rotation and this channel is engaged by a cam follower 18 which is in the nature of a bell-crank and is hingedly carried by the frame of the tower 2 through the hinge pin 19 and is coupled to the windmill pump rod 17 by the hinge pin 20 to give the required up and down motion, the cam as said being arranged to give the maximum effect, such as a slow lift and quick return of the pump rod. The dotted arrow in FIG. 4 shows the direction of rotation of the cam.

A cam used in this way. makes it possible to

vary the irate of motion of the pump rod on the up or down stroke or to increase or decease either of these strokes according to requirements, but while the form shown is a useful one it should be realised that other forms of cam can be used, and also the type of cam follower can be varied to suit the applica¬ tion to which the windmill is to be put.

Also, it is not always necessary to use a cam and follower as the windmill can be put to uses other than actuating a pump rod.

The arrangement outlined gives a highly effective windmill in that firstly the scoop-shaped blades which are used are of a more effective nature and secondly the rotational power which is generated as the blades are driven by the wind can be varied by an appropriate selector of the form of the device.

Referring to FIG. 2 it will be noted that with four blades in each vertically spaced row, each row is rotated in relation to each other row by an amount such that in plan a uniformly spaced pattern of all blades is presented.

This, together with the angling of the blades by having the blades of the upper row upwardly inclined outwardly and the blades of the lower row downwardly inclined outwardly or by further separating the rows vertically, ensures that there is minimum wind interception by forwardly positioned blades during rotation so that rearwardly positioned blades are still effectively driven.

This assembly allows the new windmill to be attached to existing towers, if that is required,

permits a selection of the number of blades or scoops which are used and their spacing around the axis because of the existence of a series of flanges, and in the case of application to a well pump, ensures that the pump rod is actuated at the best possible rate during each part of the pump stroke.

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