GB2302142A

GB2302142A - Hydroelectric generating device; water wheel

Info

Publication number: GB2302142A
Application number: GB9612364A
Authority: GB
Inventors: Frederick Arthur Dennis
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-06-13
Filing date: 1996-06-13
Publication date: 1997-01-08
Anticipated expiration: 2016-06-13
Also published as: GB9512004D0; GB2302142B; GB9612364D0

Abstract

A hydroelectric generating device for converting fluid motion into rotary power comprises a circulating body, e.g. a roller 9, having pivotally attached blades 1, with means 4, 5 to limit the pivoting in one direction, but, in the other direction, the blades fold against the circulating body so as to maximise the driving forces and minimise drag. As shown, the device comprises a water wheel. It may be adapted for tidal flow (fig 4), may comprise an endless belt (fig 5), and/or may have blades (35, fig 11) with an extension (37) at an angle. It may also comprise a disc (40, fig 12) having axially extending blades so that it will also operate effectively when the current is reversed.

Description

Device for Hydroelectric Generation The present invention relates to devices for turning the motion of fluid into rotary power, more particularly but not exclusively to water wheels, rollers or endless belts for hydroelectric generation and more especially to such devices having flexibly mounted blades or like means for trapping water to cause rotation.

It has long been known to use the flow of water as a source of power, be it the current due to the natural flow of a river, due to an artificial head being created, for example by a dam, or even tidal flow.

In all these cases the flow of water has been used to rotate a body and the rotation of the body, for example a water wheel or a water turbine, has been used, either to operate machinery directly or to generate electricity. The flow of water can be transferred to motion of the body by means of protrusions, for example blades, spoon shaped protrusions or even buckets located on the outside of the body and so positioned as to obstruct the flow.

Efficiency of the energy transfer process depends on the ability of the protrusions to trap the flow combined with a minimisation of drag forces. In an example in which the body is essentially a barrel fixed horizontally and afloat in the water or submerged, drag occurs principally during that part of the motion when the blade is moving at right angles to the direction of flow.

Various ways of shaping the blades etc to minimise drag are known but the effectiveness of these is reduced by the inability to effectively remove drag at these critical points in the rotation of the body.

A recent innovation for a hydroelectric generating body which consists of an endless belt on rollers, is known. In this example the blades themselves are hinged and are anchored, by a pivotally mounted rod, to a point further along the belt in a direction opposite to that of the flow. The blade is thus forced to bend as the straight line distance between the base of the rod and the base of the blade changes where the belt curves. Thus the blade bends at the crucial draginducing parts of the motion but does not retract fully. Drag is reduced but is still present.

An object of the present invention is to improve on the way in which drag forces are dealt with so as to provide an economical way to utilise the flow of water to provide power.

In accordance with the present invention there is provided a device for converting the motion of fluid into rotary power, the device including a circulating body for immersion in a fluid, and having projections extending from the circulating body into the fluid to translate fluid flow into motion of the body, wherein the projections are pivotally attached to the body and the device further includes means for limiting the extent of pivoting of the projections in one direction, the extent of pivoting of the projections in the other direction not being limited by the said limitingmeans.

In use the circulating body is placed in the fluid such that the flow pushes the blades against the means for limiting. Thus the means for limiting serves to transmit the energy of the flow to the body.

Where the device is partially submerged, such an arrangement allows the projection or blade to be retracted when entering the water on the downstroke and, on the upstroke, to take an intermediate position between the flow and drag forces so that no net drag is transmitted to the body.

In an embodiment the projections are blades and they may be attached by hinges to the body. The circulating body may be a rotary drum with the blades attached to the curved surface. The limiting means may be a semicircular fin projecting outwards from the body at right angles to the blade and fitting into a slot in the blade. It may include a protrusion extending outwardly from the fin to block further rotation of the blade. The limiting means may be fixedly mounted.

Alternatively the limiting means may be adjustable.

The fin may, for example, have a series of holes, through one of which a peg may be inserted to serve as the limiting means. As another alternative the fin may be dispensed with altogether and a strap or rope may be used to anchor the blade. This latter alternative is particularly appropriate when the circulating body is an endless belt.

The circulating body may instead be a rotating disc. The blades may be pivotally attached to one or both of the flat surfaces of the disc. The limiting means may again be a fin with a protrusion.

Alternatively a second disc or flange, coaxial with the first disc and located at a predetermined, and perhaps adjustable, distance therefrom, may provide the limiting means. Again a strap or any other arrangement known to the skilled man may be equally appropriate.

Two such discs may be placed back to back.

Spacing means may be provided between the discs. The device may be submerged totally in the water and the disc may be orientated horizontally or vertically or at any intermediate orientation.

The blades may be flat. Alternatively they may be curved in such a way as to maximise the effect of the flow on the body. In a preferred embodiment they are curved to the same extent that the body itself is.

Only thus can the blades ever be fully retracted.

Channel means may be used to channel water past the device and such a means may comprise a sluicing arrangement.

The body itself may normally be expected to be linked, by a transmission system including drive shafts, gears, belts and pulleys, to a generator. An effective arrangement for the transmission system is important for the efficient utilisation of the power obtained and in particular the skilled man will take care with the arrangement bearing in mind that the body may be floating. The body may for example rise and fall with the tide.

For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, purely by way of example, to the accompanying drawings in which: Figure 1 shows the mounting of the blade in a first embodiment of the invention, Figure 2 shows the mounting of the blade in a second embodiment, Figure 3 shows the blade of Figure 1 mounted on a first variant of a water wheel, Figure 4 shows the variant of Figure 3 adapted for tidal flow, Figure 5 shows a second variant of a water wheel, Figure 6 shows how a part of Figure 5 may be linked mechanically to external machinery, Figure 7 shows a linkage mechanism for the variant of Figure 3, Figure 8 is another view of the linkage mechanism shown in Figure 7, Figure 9 shows another variant of the device, Figure 10 is a perspective view of te device of Figure 9 with details of the latching mechanism shown, Figure 11 shows a variant of the blade attached to a roller, Figures 12 to 14 are another embodiment of the invention, Figure 15 is a variant of the embodiment of Figures 12 to 14, and Figure 16 shows a device according to the invention placed in a sluice gate.

Figure 1 illustrates in conceptual form a first embodiment of the mounting of a blade 1 on a surface 2 which may be the surface of a water wheel.

The blade 1 is attached at one end to the surface 2 via a hinge 3 so that it is fully rotatable against the surface.

The centre of the blade 1 has a slot through which a semi-circular fin 4, fixedly mounted on the surface 2, fits. The fin 4 has a series of holes through any one of which a rod or pin 5 may be fitted. Once fixed the rod 5 serves to limit the rotation of the fin because the rod as it extends from the fin cannot fit through the slot.

In an embodiment it is possible to dispense with the slots and the rod and simply have a permanent protrusion extending from the fin 4. This would serve to make manufacture and use easier but would remove the option of being able to adjust the power output of the water wheel.

In use the useful, power generating water flow comes from the direction of the arrow 6 and drag forces from that of the arrow 7. Thus the useful flow serves to open the blade 1 and push it against the rod 5.

Power is transferred from the rod 5 to the water wheel.

However, when drag forces predominate, as they do when the blade is at or near the vertical parts of the rotation, the blade takes up an intermediate position between the useful and drag forces and no net drag is transmitted to the water wheel because there is no means of transmitting any force in the direction of the arrow 7 to the water wheel.

In Figure 2 an alternative embodiment for anchoring the blade is disclosed. In this embodiment a flexible strap 8 is used for limiting the rotation of the blade in the direction of flow 6. Again, because the strap 8 is flexible, forces in the direction of the arrow 7 cannot be transmitted to the water wheel.

Suitable materials for the strap 8 may include rope, leather or synthetic materials which are strong, flexible and will maintain their properties in water.

Figure 3 shows how the blades 1 may be mounted on a practical water wheel 9 or drum rotating in the direction of arrow 20. In this embodiment the blades are curved for efficiency in capturing the flow. The blade limiting means of Figure 1 is shown here although that of Figure 2 is also applicable. As an alternative a simple stop means built into the hinge may be considered but due to leverage considerations it is not preferred as it must be strong enough to transmit the force of the flow to the wheel.

Four blades, la-ld, are shown at different stages of the circulatory cycle. Blade la is folded against the water wheel body due to gravity and, if submerged, due to fluid flow. Blade lb is beginning to open out as it enters the water. The drag force caused as water attempts to enter behind the blade as it opens is not transmitted to the water wheel. Blade ic is fully extended against the limiting means as the flow gets behind it and blade ld is shown folding as it rises out of the water. Again the drag forces which arise when a fixed blade tries to lift the water above it and when water is sucked out from beneath it, are eliminated.

Figure 4 shows an embodiment of a water wheel designed for dealing with tidal flow. The wheel 9 is designed to float. An axle of the wheel 9 extends outwardly and terminates in a bearing 10 which fits into a channel in a fixed vertical post 11. As the water level changes with the tide the wheel 9 rides up and down the post.

Figure 5 shows an embodiment in which the blades 1 are attached to a circulating body in the form of an endless belt 12. The endless belt runs over a series of rollers 16 one of which is connected to a drive shaft 13. In this case the strap shown in Figure 2 is the most appropriate means of arresting the rotation of the blades.

Figure 6 shows how the shaft 13 may be linked by a drive belt 14 to a generator 15 or the like.

Figure 7 shows how two wheels of the type shown in Figure 3 may be linked by a drive chain 17 to operate a cog wheel 18 leading to a generator.

The drive chain passes through a jockey pulley 19 arranged to compensate for changes in level of the water and take up any slack on the drive chain.

Figure 8 is a view from behind of the way in which the wheels are linked to a generator.

The wheel 9, having collapsible blades 3, is supported by floating outriggers 25 so that it rides up and down with the water level in a frame 26 which includes the vertical posts 11.

A first cog-wheel 27 is attached to the axle 13 of the wheel 9 and is linked by the drive chain 17 to operate the cog wheel 18 which is linked to the generator 28.

An inlet valve 29 is located on each of the outriggers.

Figure 9 shows a variation of the device of Figure 8 in which the drum 9 is built in two sections, 9a and 9b. The blades in the respective sections are offset from one another.

Figure 10 is a perspective view of the variation of Figure 9. Here the roller 9 is shown in its two sections which are separated by discs 30, 31 and 32.

Holes 33 in the walls of the discs allow latches 34 to be placed to halt rotation of the blades.

In Figure 11 the roller 9 is shown with a blade 35 made up of a main section 36 and a fin-like extension 37 which protrudes at an angle. The angle is carefully chosen to maximise efficiency. Clearly it should allow water to enter the gap smoothly as the blade dips below the surface and it should not retain water as the blade rises.

In the above embodiments the fins have extended radially from the rotary drum. Such an arrangement is advantageous when the drum is partially submerged.

It will work if the drum is fully submerged because the blades fold for the return part of the stroke. Provided the device is fully submerged it will also work if the direction of the current changes, for example when using tidal power since the upper part of the stroke can also be used to transfer power.

Figures 12 to 15 show embodiments which are specifically intended to be fully submerged. Here the blades are arranged to extend axially from the rotating body which is in this case a disc.

In Figure 12 a rotary disc 40 rotates about a central shaft 41 which is itself supported by bearings 42. Two smaller discs 43 and 44 extend about the central shaft 41 on either side of the main disc 40.

The distance between the main 40 and the smaller discs 43 and 44 may be adjusted by means of adjustable pins 45. Blades 46 are pivotally attached to the flat surfaces on either side of the disc 40. They are able to open as far as the smaller discs 43, 44 which thereby act as regulators.

In use the device is placed in the water so that the shaft 41 is vertical. In a current the blades on one side of the disc will open and those on the other side will close. If the current changes direction the device continues to work just as efficiently as long as the current remains broadly within the horizontal plane.

The device can be placed in the water so that the main shaft 41 is horizontal. However such an arrangement is only appropriate when the only change in direction of the current is a full 1800 reversal.

In the drawing the blades 46 are shown as triangular. They are attached to the main disc by hinges 47. Those blades below the shaft 41 are shown as open and those above are closed. In the precise arrangement of Figure 12 this indicates a current heading into the paper.

Figures 13 and 14 are two variants of the device shown in Figure 12 in which the main disc is in two parts with a separator body 48 inbetween.

Figure 15 is a further variant in which the small outer discs are replaced by a fin 50 and a latch 51 fitted into a hole in the fin 50. The fin extends from the main disc 40 through a slot in the blade 46. The latch acts to limit the rotation of the blade.

The power output is improved if the power of the passing water is improved and one way of achieving this is to use a sluice.

Figure 16 shows the device of Figure 12 placed in front of a sluicing arrangement 60. The outer walls 61 of the sluice gate 60 concentrate the water so that more of it passes the device.

Claims

CLAIMS:

1. A device for converting the mot:ion of fluid into rotary power, the device including a circulating body for immersion in a fluid, having projections extending from the circulating body, wherein the projections are pivotally attached to the body, and wherein the device further includes limiting means for limiting the extent to which the projections are pivotable in one direction, the extent to which the projections are pivotable in the opposite direction not being limited by the said limiting means.

2. A device according to claim 1 wherein the circulating body is a rotatable drum and wherein the projections are blades attached to the curved surface of the drum.

3. A device according to claim 1, wherein the circulating body is an endless belt.

4. A device according to claim 1, wherein the circulating body is a disc and wherein the projections are blades each attached to either one of the flat surfaces of the disc.

5. A device according to claim 2 or claim 4, wherein the limiting means are fins extending from the circulating body through slots provided in the projections and having latching means extending perpendicularly from the fins in the vicinity of their outer ends to limit the rotation of the projections.

6. A device according to claim 4, wherein the limiting means is a second disc coaxial with the circulating means and placed at a predetermined distance therefrom.

7. A device according to claim 6, wherein the predetermined distance is adjustable.

8. A device according to claim 2, wherein the limiting means is a disc coaxial with the drum, having latching means placed in receiving means in the disc to protrude into the path of a blade to limit rotation of the blade.

9. A device according to claim 4, 6 or 7, or claims 4 and 5 combined, wherein both flat surfaces of the disc have blades attached.

10. A device according to any preceding claim wherein the projections are flat.

11. A device according to any one of claims 1 to 9, wherein the projections are curved.

12. A device according to any preceding claim linked via a transmission arrangement to an electrical generator.

13. A device according to any preceding claim when placed in the vicinity of the mouth of a sluicing arrangement.

14. A device for turning the motion of water into rotary power, substantially according to any one of the embodiments hereinbefore described with reference to the accompanying drawings.