GB2237330A - Wind motor or hydraulic turbine - Google Patents

Abstract

A machine for utilising the energy in fluid flows comprises a support (21), Fig 9, and central drive shaft (22), Fig 9, connected to a support arm 23, each arm 23 carrying at least one vane (24), 25, 26, (27), Fig. 11. The vanes can pivot on bearing rods (28), Fig 12, and may be flexible so that they can present the most advantageous profile to the fluid flow as the support arms rotate about the central drive shaft 22. More than one such machine may be situated in a pipe (37), Fig 27, through which fluid flows. <IMAGE>

Description

"Drag Machine" This invention relates to a drag machine and in particular a drag machine for utilizing the energy available in winds, rivers and tides and currents.

Man has since ancient times tried to harness the power of wind, river and tide, for raising water, grinding corn, and now generating electricity. At present the main source of electricity is the burning of fossil fuels. However, fossil fuels will not last forever and have been associated with pollution problems such as acid rain and the greenhouse effect. Nuclear power, which is the main alternative to fossil fuel at present, is potentially disastrous and produces serious waste disposal problems.

Consequently, the use of renewable energy sources must be maximised in order to overcome these pollution and waste disposal problems.

One of the largest renewable energy sources is tides, which remain largely unused. However, in France tides have recently been harnessed by building a large barrage across an estuary, then feeding the tidal flow through turbines.

This is a very complex and expensive engineering project.

The applications for the electricity produced by drag machines are extremely wide ranging from being the energy source of hydroponic plants and market gardens to meeting the needs of the domestic user in remote or isolated locations.

Existing machines which extract energy from wind, tide, rivers and waves, all suffer from one major problem; they must be engineered to survive conditions well in excess of their working parameters. In other words they must be strong enough to survive the storm which occurs say once in ten years, which might otherwise destroy them. The fluid pump solves this problem by being situated under water, deep enough not to be affected by surface agitation ie storms, yet still within the range of air-breathing divers, where the tidal flow is predictable.

The design of the drag machine is based on the vertical axis mills, the origins of which go back to vertical axis machines used in Tuscany and Asia in ancient times. The need for one side of a drag machine to present a barrier to the moving fluid and the other side to present as little resistance as possible has been well documented. "The advantages and disadvantages of vertical and horizontal windmills" by Robert Beatson published in 1798 lays down the requirements for a vertical axis drag machine and describes a design which incorporates movable vanes. Patent Specification No 1,508,796 by L C Hill published April 1978 describes a rotary apparatus with movable vanes similar to Beatson's design except that the movable vanes have been turned through 90 and have a vertical turning axis instead of a horisontal one.US Patent 4,346,305 by F B White and B S Dak published in August 1982 describes a similar machine which incorporates a feathering system. The drag machine does not need a feathering system as it can be engineered to suit known maximum tidal flow rates.

Drag machines suffer from bending forces acting on the drive shaft due, in part, to the vertical axis low tower design used in their manufacture to date.

There now follows a description of the basic principle upon which the drag machines is based, with reference to the accompanying drawings Figs. 1-8.

An omnidirectional tide pump comprises a vertical shaft held in bearings and able to rotate. Mounted on top of this shaft are three equi-spaced horizontal arms, having four vertical bearing rods mounted on them. Vanes are fitted over the outer three bearing rods on each arm. The vanes are so arranged that they are opened and closed by the moving fluid, in such a manner that the force on them starts from zero, rises to a maximum and returns to zero, over 180 degrees of revolution. During the remaining 180 degrees of revolution the vanes are opened by the moving fluid in such a manner that the vanes provide as little resistance as possible to the moving fluid. Each of the arms is identical.

Fig. 1 shows, in elevation, the vertical shaft held in bearings, the three arms, and the vertical rods; Fig. 2 shows, in plan, the three arms, and the vertical bearing rods; Fig. 3 shows, in elevation and plan, the vane; Fig. 4 shows how a vane is fitted over bearings rod and the vanes possible movement; Fig. 5 shows how all the vanes are fitted in a no fluid movement situation; and Figs. 6, 7 and 8 show direction of rotation, fluid movement direction, and twelve different arm positions for one complete revolution, each position being lettered in sequence from 'A' to 'L'.

Referring to Figs. 1, 2, 3, 4 and 5 of the drawings, the drag machine comprises a central vertical shaft 10 and arms 11 with bearing rods 12 mounted on them. Vanes 13 are fitted over the bearing rods 12.

Referring to Figs. 6, 7 and 8 of the drawings, direction of rotation is shown by arrow 14. Direction of fluid movement is shown by arrow 15. Twelve different positions of arm, are shown lettered 'A' to 'L' in sequence for one revolution of drag machine.

Position 'A' shows vanes having just closed under action of moving fluid. As drag machine rotates, pressure on vanes builds up form zero, at position 'A', to a maximum at position 'D' and back to zero at position 'G'. Between positions 'G' to 'H' pressure builds up on opposite sides of vanes causing them to open out until in position shown in position 'H'. From position 'H' to 'A' vanes are open and cause as little resistance as possible to moving fluid.

An object of the present invention is to improve the design of presently available drag machine so as to reduce both the drag on the vanes and the bending force on the central shaft.

According to the present invention there is provided a fluid pump comprising a substantially vertical tower support, a shaft rotatably mounted in a bearing arrangement carried by the tower support and connected via a second bearing arrangement to a plurality of equally spaced support arms which extend radially outwards from the central shaft, each support arm carrying at least one substantially vertical bearing rod having a vane pivotally attached thereto, the support arms being so arranged that any force acting on a vane will cause the support arm to process about the central shaft with the plane of maximum force lying in the plane containing the bearing arrangement.

Preferably, each support arm comprises a single member which is positioned substantially horizontally with respect to the central shaft.

Each arm may have one or more vanes spaced along the length of the arm, each vane extending equidistantly above and below the support arm.

Alternatively, each arm may have one or more pairs of vanes spaced along the length of the arm, each pair comprising a first vane positioned above and a second vane positioned below the support arm.

In another arrangement, the support arm may bifurcate in a vertical plane symmetrically with respect to the horizontal plane containing the second bearing arrangement.

Preferably, each support arm comprises a substantially vertical bearing rod attached between the branches of the arm, near the end of the support arm.

Preferably, each bearing rod is positioned so as to allow the attached vane to lie in contact with the arm along the whole length of the vane and to rotate in a horizontal plane about the bearing rod, under external force.

Preferably, the support arms are connected, in series, to each other with tensioning wire to improve the structural strength of the drag machine.

Further according to the present invention there is provided a semi-flexible vane for use with tide pumps, comprising a quadrilateral of material formed so that the vane is rigid in a first plane and flexible in a second plane substantially-orthogonal to the first plane.

Preferably the vane is formed from a plurality of rigid strips flexible connected in series along their length.

Alternatively, the vane may be formed by encasing a plurality of rigid rods or strips between sheets of flexible material.

Still further according to the present invention there is provided a drag machine as hereinbefore described comprising a plurality of semi-flexible vanes as defined above.

Preferably, the support arms each comprise a means of preventing a vane from rotating round the end of the arm and being located on the opposite side of the arm.

Preferably, the support arm is extended beyond the position of the vane pivot to prevent the vane from rotating round the end of the arm.

Alternatively, an elliptical member may be located at the end of the arm to prevent the vane from rotating round the end of the arm; or a semi-elliptical member may be located at the end of the arm, pointing towards the side of the arm to which the vane is connected to prevent the vane from rotating around the end of the arm.

Yet still further according to the present invention there is provided a drag machine adapted for use within a conduit, the drag machine comprising a central shaft having a bearing arrangement positioned at one end of the shaft, a plurality of equally spaced support arms extending radially outwards from the central shaft, each arm support carrying at least one substantially vertical bearing rod having a vane pivotally attached thereto, the support arms being so arranged that any force acting on a vane will cause the support arm to process about the central shaft with a plane of maximum force lying in the plane containing the bearing arrangement.

Preferably the bearing arrangement is recevied within one of the walls of a conduit with which the drag machine is used.

Preferably, a pair of drag machines, as described above, may be used to facilitate the generation of energy from diffeent sides of a fluid flow within a conduit by rotation in opposite directions.

Preferably, each drage machine comprises three support arms.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings in which: Fig. 9 illustrates a tower support tall enough to support a bearing arrangement which lies on the centre line of the force applied to the vane in accordance with the present invention; Fig. 10 illustrates a drag machine comprising one vane above and one vane below a radial support arm; Fig. 11 illustrates a drag machine comprising one vane which extends below and above the radial support arm; Fig. 12 illustrates the pivot points at the side of the support arm; Figs. 13 and 14 illustrate the opening movement of a vane; Fig. 15 illustrates a semi-flexible vane;; Fig. 16 illustrates a vane shaped to provide a uniform force along the vane and support armt Fig. 17 illustrates a drag machine where one vane has flipped round the wrong side of the support arm; Figs. 18 and 19 illustrate methods of preventing a vane from flipping round and becoming trapped on the wrong side of the support arm; Fig. 20 illustrates a bifurcated support arm; Fig. 21 illustrates the support arm linked together with tensioning wire; Fig. 22 illustrates a bearing arrangement design; Figs. 23, 24 and 26 illustrate methods of preventing a vane form flipping round and becoming trapped on the wrong side of a bifurcated support arm; and Fig. 25 illustrates the shape of a vane used in conjunction with the support arms as illustrated in Figs. 24 and 26.

Fig. 27 illustrates a pair of drag machines situated within a conduit so as to utilise energy from different sides of the fluid flow.

With reference to the drawings Fig. 9 illustrates a tower support 21 and central drive shaft 22 connected to a support arm 23 in which the support arm 23 is connected to a plurality of vanes 24. Fig. 10 illustrates the same system whrein the plurality of vanes 24 has been replaced by a single vane 25 above and another single vane 26 below and the support arm 23. Fig. 11 further illustrates the system wherein the vanes 24, 25 and 26 have been replaced by a single vane 27 per support arm 23.

Fig. 12 illustrates the position of bearing rods 28 on the support arm 23, so that the pivot point 29 is near the edge of the support arm 23. This positioning of the pivot point 29 allows the vane 27 to lie along, and in contact with, the support arm 23 for the whole of the length of the vane 27.

Fig. 15 illustrates a semi-flexible vane 27, which can flex in the plane parallel to the support arm 23 thus reducing the pressures and consequent drag, on the vane 27.

Fig. 22 shows a possible top bearing arrangement, it utilizes taper roller 30 and needle roller 31 bearings.

Fig. 23 shows how the bearing arrangement 32 shown in Fig.

22 can be used to improve arm structure. The round guide 33 shown at the end of the arm 23 can be simplified, as shown in Fig. 24 the guide lies on the central axis of the arm 23, and also supports the vane 27.

The vane support 37 shown in Fig. 24 are held together by a pin passing through the holes in the arm and vane. This pin should be able to be fixed to the arm 23 in the three support positions.

The shape of the guide 33 will be designed according to a combination of two factors, one is the vane 27 length, the other is the path the vane 27 follows as it moves from the fully closed to the fully open position. The vane path will depend upon rotational speed of the drag machine and the fluid velocity.

The teardrop shape of the guide 33 shown in Fig. 26 defers to both factors.

In use the greatest output from the drag machine will be obtained when the drag machine is situated in the greatest tidal current flow. Mouths of sea lochs and fjords should be used to advantage.

Table 1 illustrates the power produced by a im vane 27 for different flow rates.

Fouling may be a problem in these locations and the arms 23 and vanes 27 should be anti-foul coated.

The drag machine in action will use the energy of the moving tide to drive a pump which will pump sea water onto the shore where the sea water is used to drive a generator for producing electricity, the exhausted sea water is either run off back into the sea or used for marine fish farming on land. One pipe is the only connection between the fluid pump and the shore based generator.

Because of the corrosive properties of sea water it may be advantageous to supply fresh water to the drag machine from a reservoir. The fresh water would then be used to drive a generator or to be allowed to rise up and into the reservoir of an already existing hydro-electric scheme; in which two pipes would be required from shore to drag machine.

For wind applications the drag machine will be directly geared to an electric generator.

TABLE ONE Energy available per square metre in water.

Flow Rate (knots) Velocity Power kw metre/second metre/second 1 0.515 0.068 2 1.03 0.56 3 1.544 1.87 4 2.059 4.36 5 2.55 8.29 6 3.088 14.7 7 3.6034 23.4 8 4.1182 34.9 9 4.6325 49.7 10 5.147 68.2 For tide applications the drag machine will be coupled to a water pump. Water will be pumped ashore to a land based electric generator. Vanes 27 and arms 23 should be engineered to be neutrally bouyant, that is they neither float nor sink, relieving some of the pressure on the bearings 30 and 31. The drag machine should be engineered so that the arms 23 and vanes 27 can be removed/refitted without disturbing the tower bearings 30 and 31 nor the water pump, as shown in Fig. 22. The water pump and the tower should be able to be removed from the foundations while leaving the pipework intact.

Potentially catastrophic forces are imposed upon each arm 23 in turn as the vanes 27 move from the closed position to the open position Fig. 14 shows a vane 27 in the act of opening. Arrow 34 shows direction of rotation. Arrow 35 shows direction of fluid movement. As the arm 23 pulls the vane 27 through the fluid in direction of arrow 34. High pressure builds up at arrows 'A' and 'B'. If arrows 'A' are considered to be a fulcrum then forces at arrows 'B' will need to be balanced by a force at arrow 'C'. This force at arrow 'C' is the force which the arm 23 must exert on the vane 27 in order to drag it through the fluid. An equal and opposite force to the force at arrow 'C' is shown at arrow 'D'. This force at 'D' can be thought of as being the drag as the vane 27 opens.

Fig. 13 shows a vane 27 in the act of opening. As the arm 23 drags the vane 27 through the fluid, low pressure is generated at position 'X' and to a lesser extent at 'Y'.

These areas of low pressure cause vortices to be formed as indicated by arrows 35. These vortices cause the vane 27 to take more time to open fully, and hence extend the vortex influence on the level of vane 27 opening drag. As the magnitude of the drag force can be related to the volume of -fluid which is either changed in direction or velocity it can be seen that the formation of vortices causes a large amount of drag. The formation of vortices must be kept to a minimum.

The drag forces caused by the vane 27 acting like a lever (Fig. 14) and the formation of vortices (Fig. 13) can be eliminated by making the vane 27 flexible in one axis and rigid in the other.

Fig. 15 shows the semi-flexible vane 27 in which the flexibility allows the vane 27 to flap in the moving fluid.

Thus the vane 27 is able to equilize the pressure on each side of itself, eliminating the formation of vortices as the flexible vane 27 cannot act as a lever. The rigidity still allows the vane 27 to act as a large flat surface in the driving half of its movement.

When moving the part of the vane 27 closest to the centre of the drag machine will move slower than the part of the vane 27 furthest from the centre, relative to the moving fluid.

Therefore, the pressure on the vane 27 will not be uniform along the length of the arm 23. Greatest pressure is exerted upon that part of the vane 27 closest to the centre of drag machine rotation. Pressure drops as the radius from the centre increases. This will be one of the limiting factors on maximum drag machine diameter. This pressure difference along the length of the arm/vane could be viewed as being beneficial, however if uniform force is desired along the length of the arm/vane, then the vane 27 shoald be shaped as shown in Fig. 16. The height 'H' of the vane 27 at any given point on the vane 27 will be related to the radius from the drag machine axis, and the desired force on the arm 23 at that radius.

The design so far will cope with a continuous fluid movement as in rivers, but when the fluid stops and starts in winds and tides a major problem could arise as the fluid starts to move.

Fig. 17 shows a situation where a vane 27 has flipped round to the wrong side of the arm 23 and is acting as a large flat surface on the side of the drag machine which should cause as little resistance as possible to the moving fluid.

Two vanes 27 are in direct opposition to each other and catastrophic failure is imminent. This situation must be avoided. An easy solution would be to make the arm 23 longer so that it stops the vane 27 from being able to swing round to the opposite side. This increases the drag machine diameter by quite a large margin as illustrated in Fig. 18.

The quadrilateral vane 27 shown in Fig. 17 can be used to advantage by making the arm 23 long enough to allow only part of the flexible vane 27 the possibility of getting to the opposite side of the arm 23. The moving fluid would then impinge upon part of the vane 27 and restore it to its proper working position. The vane 27 in the position shown in Fig. 18 causes problems because it is doubled back on itself. The part of the vane 27 on the opposite side of the arm 23 is being forced against the arm 23 by the moving fluid. It will take quite large forces, to drag it back to its proper position, which will need to be transmitted along the length of the vane 27.These vane 27 "drag back" forces can be reduced by adding a round or ellipitical guide 33 to the end of the arm 23 as shown in Fig. 19 this makes it impossible for the vane 27 to become stuck" round the wrong side of the arm 23 while keeping the drag machine diameter to a minimum.

The cirucumference of the round or elliptical guide 33 will be related to the length of the vane 7. If an elliptical guide 33 is used then the minor axis of the ellipse should be in line with the arm 23 axis.

When the drag machine is under load, large forces act upon the vane 27, these forces severely challenge the vanes 27 rigidity, because the vane 27 is only supported along its centre line where it meets the arm 23 it is liable to be bent over the arm 23. Redesigning the arm 23 as shown in Fig. 20 will alleviate this problem and give better support to the vane 27 pivot point fixings 29. When it is structurally desirable to link the arms 23 together with tensioned wire 36 then the fixing points should be as shown in Fig. 21. These wires 36 will be above and below the arms.

A drag machine as described herein does not need a barrage and can be engineered to suit the needs of a single croft or an island community. Anyone living near the sea could benefit from the electricity produced by the fluid pump.

Current problems associated with marine fish farming could be solved by utilizing the drag machine because not only does the drag machine produce electricity but also a continuous flow of sea water which would make marine fish farming on land in tanks a viable proposition. The fouling of the sea bed under fish farm nets would then be alleviated. The treating of the fish stock for parasitic attack such a sea lice and diseases would be made simpler and more effective. Environments for other species eg lobster, crab, scallops, mussels and oysters would be simpler to create and maintain. The working environment for the men who have to go out in all weathers to service fish farms would be improved and would be considerably safer.

Fig. 27 illustrates a further embodiment of the drag machine wherein the drag machine is used to generate energy from the fluid flow within a conduit or pipe. The drag machine comprises a central shaft 38 connected to three support arms 40 each of which is pivotally connected to a vane 41. The central shaft 38 further includes a bearing arrangement 42 at the base and at the top of the shaft 38 so as to enable rotation of the shaft 38. One or both of the ends of the shaft 38 may be attached to an external shaft 43 which enables removal of energy from the drag machine.

The vanes 41 only receive a force from the fluid which aids in the rotation of the drag machine when each vane 41 lies against its support arm 40. Thus as each vane 41 only lies against its support arm 40 for half of its rotation only half of the available force from the fluid is utilised.

This situation can be overcome by employing two counter processing drag machines, each of which utilises the force applied by half of the fluid, as illustrated in Fig. 27.

Modifications and improvements may be incorporated without departing from the scope of the invention.

Claims (19)

1. A drag machine in the form of a fluid pump comprising a substantially vertical tower support, a shaft rotatably mounted in a bearing arrangement carried by the tower support and connected via a second bearing arrangement to a plurality of equally spaced support arms which extend radially outwards from the central shaft, each support arm carrying at least one substantially vertical bearing rod having a vane pivotally attached thereto, the support arms being so arranged that any force acting on a vane will cause the support arm to process about the central shaft with the plane of maximum force lying in the plane containing the bearing arrangement.

2. A drag machine as claimed in Claim 1, wherein each support arm comprises a single member which is positioned substantially horizontally with respect to the central shaft.

3. A drag machine as claimed in Claim 1 or 2, wherein each arm has one'or more vanes spaced along the length of the arm, each vane extending equidistantly above and below the support arm.

4. A drag machine as claimed in Claim 1 or 2, wherein each arm has one or more pairs of vanes spaced along the length of the arm, each pair comprising a first vane positioned above and a second vane positioned below the support arm.

5. A drag machine as claimed in Claim 1, wherein the support arm bifurcates in a vertical plane symmetrically with respect to the horizontal plane containing the second bearing arrangement.

6. A drag machine as claimed in Claim 5, wherein each support arm includes a substantially vertical bearing rod attached between the branches of the arm, near the end of the support arm.

7. A drag machine as claimed in Claim 6, wherein each bearing rod is positioned so as to allow the attached vane to lie in contact with the arm along the whole length of the vane and to rotate in a horizontal plane about the bearing rod, under external force.

8. A drag machine as claimed in any one of the preceding Claims, wherein the support arms are connected, in series, to each other with tensioning means to improve the structural strength of the drag machine.

9. A semi-flexible vane for use with tide pumps, comprising a quadrilateral of material formed so that the vane is rigid in a first plane and flexible in a second plane substantially orthogonal to the first plane.

10. A vane as claimed in Claim 9, formed from a plurality of rigid strips flexibly connected in series along their length.

11. A vane as claimed in Claim 9, formed by encasing a plurality of rigid rods or strips between sheets of flexible material.

12. A drag machine as claimed in any one of Claims 1 to 8 and including a plurality of semi-flexible vanes as claimed in any one of Claims 9 to 11.

13. A drag machine as claimed in Claim 12, wherein the support arms each include means for preventing a vane from rotating round the end of the arm and being located on the opposite side of the arm.

14. A drag machine as claimed in Claim 13, wherein the support arm extends beyond the position of the vane pivot to prevent the vane from rotating round the end of the arm.

15. A drag machine as claimed in Claim 13, wherein an elliptical or semi-elliptical member is located at the end of the arm to prevent the vane from rotating round the end of the arm.

16. A drag machine adapted for use within a conduit, the drag machine comprising a central shaft having a bearing arrangement positioned at one end of the shaft, a plurality of equally spaced support arms extending radially outwards from the central shaft, each arm support carrying at least one substantially vertical bearing rod having a vane pivotally attached thereto, the support arms being so arranged that any force acting on a vane will cause the support arm to process about the central shaft with a plane of maximum force lying in the plane containing the bearing arrangement.

17. A drag machine as claimed in Claim 16, wherein the bearing arrangement is received within one of the walls of a conduit with which the drag machine is used.

18. A drag machine substantially as hereinbefore described, with reference to and as shown in the accompanying drawings.

19. A semi-flexible vane for use in a drag machine substantially as hereinbefore described with reference to and as shown in the accompanying drawings.