GB2509892A

GB2509892A - Concentric paddle wheel with speed matching gearing at both ends to prevent blades twisting

Info

Publication number: GB2509892A
Application number: GB1219804.0A
Authority: GB
Inventors: Hugh Malcolm Ian Bell
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-11-03
Filing date: 2012-11-03
Publication date: 2014-07-23
Anticipated expiration: 2032-11-03
Also published as: GB2509892B; GB201219804D0

Abstract

An undershot waterwheel or paddle wheel comprises at least two sets of concentric blades 31, 32 supported to be driven by fluid flow. The blades supported at a smaller diameter rotate faster so each blade set rotates at a different rate. Gears 109, 110, 121, 122 are provided at both ends of the rotors, and there is a connection e.g. shaft 100 between the two ends, to ensure that the blade supports 34, 35, 36 at each end move together to prevent twisting of the rotor blades 31, 32.

Description

Improvements in or relating to Turbines

FIELD OF THE INVENTION

The present invention relates to turbines and turbine systems, such as waterwheels, of the type where blades or paddles are supported for rotation about an axis.

BACKGROUND OF THE INVENTION

Waterwheels or paddle wheels have been known for centuries and enable rotational kinetic energy to be derived from a flow of water.

A waterwheel consists of a large wooden or metal wheel, with a io number of blades or buckets arranged on the outside rim forming the driving surface. Most commonly, the wheel is mounted vertically on a horizontal axle. Vertical wheels can transmit power either through the axle or via a ring gear and typically drive belts or gears; horizontal wheels usually directly drive their load.

Waterwheels were still in commercial use well into the 20th century, but they are no longer in common use. Prior uses of water wheels include milling flour in gristmills and grinding wood into pulp for papermaking, but other uses include hammering wrought iron, machining, ore crushing and pounding fibre for use in the manufacture of cloth. Similar systems are presently being developed to obtain energy from water currents which can be utilised to create electrical energy through the use of electrical generators connected to the water wheel. GB2445284, in the name of Bell is an example of such.

In these systems, the waterwheel comprises at least one rotor at each end of a blade, which rotor is arranged to rotate about an common axis. A plurality of blades are angularly separated about each rotor. GB2445284 provides a particular arrangement wherein there are three sets of blades or paddles (these shall be referred to hereinafter as blades), supported by corresponding rotors, as can be seen from Figure 1. The physical configuration of the rotors means that each waterwheel comprises a first rotor, a second rotor and blades connecting the first rotor to the second rotor; that is to say, the rotors otherwise move independently, but are connected to each other by the blades. With specific reference to Figure 1, rotors 24, 23 and 22 rotate about a central axis A and support blades 30, 31 and 32 for rotation about said axis, via arms 33, 34 and 35 extending form hub elements 26, 27 and 28. Figure 2 show the three sets of blades of Figure 1 from another aspect.

Traditional waterwheels have extended over widths not very much more than a metre or so with the world's largest water wheel being of 1.83m in width (six foot) and are made with substantial steel beams that are either welded or bolted to the blades, manufacture accordingly being costly and the product unwieldy to transport and mount, once in place. It will be appreciated that water wheels which are used to generate electricity are becoming seen as a more acceptable renewable energy source than wind turbines; there is a requirement for such wheels to become larger, so that the energy derived from each wheel is increased.

It is also to be noted that the net energy in a tidal stream can be very large. To extract a significant amount of energy from this relatively slow moving body of water, a large cross-section of the tidal stream needs to be harnessed. However, a force acting on one end rotor may be significantly different to a force acting upon the other end rotor. To make the blades strong enough to withstand torsional forces over large distance compared with their width would be expensive and increase the mass and weight of each blade, making the water wheel inefficient, at best.

Waterwheels having a single set or arrangement of blades between a pair of rotors can have a shaft that rotates and ensures that both rotors rotate at the same speed, ensuring no torsional stresses.

Waterwheels having a plurality of sets of blades cannot benefit from the structural integrity. Notwithstanding this, a waterwheel having a single set of blades will have a central shaft connecting the rotors provides a central barrier, which when sufficiently massive in the case of a wheel being over 2m in width, would in operation cause cavitation and disturb the flow of water driving the blades. The waterwheel structure needs also to contend with surface conditions such as floating debris and slab ice -in cold environments.

Wind mills have been known for centuries to derive kinetic energy from the wind to provide energy to mill grain to produce flour. If the mechanical energy is used to drive machinery, such as for pumping water, the device is called a wind pump. If the mechanical energy is used to produce electricity, the device may be called wind turbine or wind power plant and can be connected to an electrical distribution grid or can be connected to electrical energy storage cells or batteries to charge the same. A wind turbine is a device that converts kinetic energy from the wind, also called wind energy, into mechanical energy. The concept of a plurality of blade sets can also be extended to wind turbines, where there are coaxial blade sets, similar to the patent mentioned above, except that the fluid flow is coaxial.

OBJECT TO THE INVENTION

The present invention seeks to address some of the problems encountered by multiple blade set axial flow and cross flow turbines such as waterwheel assemblies and the like. In particular the present invention seeks to provide a turbine system such as a waterwheel or wind turbine with multiple sets of blade with improved efficiency.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the invention, there is provided a cross flow turbine, such as an undershot waterwheel, having at least two sets of blades for rotation about an axis of rotation across the turbine; wherein each set of blades is supported by first and second rotors at first and second positions of support to define, in use, non-overlapping concentric paths; wherein, for each of the first to and second positions of support, the rotors associated with the separate sets of blades are coupled to an output shaft by gearing, the gearing enabling the rotors to rotate at different rotational speeds whereby to compensate for a radial distance of the blade to the axis of rotation; and, wherein the output shafts of the first and second positions of support are mechanically connected whereby to ensure that first and second rotors of each set of blades rotate at the same rotational speed about the said axis of rotation.

In accordance with a second aspect of the invention, there is provided an axial flow turbine, having at least two sets of blades for rotation about an axis of rotation across the turbine; wherein each set of blades is supported by first and second rotors at first and second positions of the turbine to define, in use, non-overlapping concentric flow paths; wherein, for each of the first and second positions of support, the rotors associated with the separate sets of blades are coupled to an output shaft by gearing, the gearing enabling the rotors to rotate at different rotational speeds whereby to compensate for a radial distance of the set of blades to the axis of rotation; and, wherein the output shafts of the first and second support positions are mechanically connected whereby to ensure that first and second rotors of each set of blades rotate at the same rotational speed about the said axis of rotation.

An advantage of the present invention is that it can assist in a reduction of the effect of differing forces that may affect different parts of a turbine blade. For example, if a turbine blade upon rotor is subject to different forces at opposite ends of the blade, the loads are resisted through the gear train and are not borne by blade itself and both rotors at each end of the blade rotate in unison save for any stress and backlash factors. Without the resistive force of the gearing mechanism in water wheels, the blades would be subject to very high distributive loads. It will be appreciated that the longer/wider the blades are, then the greater the differences in forces that could be experienced.

In accordance with a third aspect of the invention, there is provided Is a method of using a turbine, said turbine having at least two sets of blades for rotation about an axis of rotation across the turbine; wherein each set of blades is supported by first and second rotors at first and second positions of support of the turbine to define, in use, non-overlapping concentric paths; wherein, for each of the first and second positions of support, the rotors associated with each set of blades are coupled to an output shaft by gearing, the gearing enabling each set of blades and rotors to rotate at different rotational speeds, whereby to compensate for a radial distance of said each set of blades to the rotational axis; and, wherein the output shafts of the first and second positions of support are mechanically connected for rotation; said method comprising the steps of enabling a flow of fluid to bear against the respective blades of the turbine, causing respective first and second rotors of each blade to rotate, the gearing enabling rotors of each position of support to rotate, by virtue of the mechanical connection to ensure, in use, that first and second rotors of each set of blades rotate in unison about the said axis.

The mechanical connection can comprise a shaft connecting the output shafts of the first and second positions of support. The output shaft of the first and second shafts may comprise the same shaft. The output shaft of each side may drive a series of gears whereby to enable a shaft to drive an offset shaft parallel with the axis of rotation. The output shafts of first and second positions of support may be connected by a train of gear wheels.

to The output shaft of each position of support may drive a sprocket which is connected with a cooperating sprocket via a chain drive to drive an offset shaft parallel with the axis of rotation. The cooperating sprockets may, via suitable 900 drive systems enable further chains to be employed, said further chains being arranged in parallel fashion with respect to the axis of rotation. The mechanical connection can comprises first and second pulley wheels connected by a notched v-belt, which drive a shaft offset and parallel to said axis of rotation. Indeed, the mechanical connection can comprises first and second pulleys connected by a continuous notched v-belt, which drive, via 90° drive systems with pulleys enable a further notched v-belt to be employed, said further notched v-belt being arranged in parallel fashion with respect to the axis of rotation.

The synchronisation may also be performed by hydraulics.

In use, the first and second plurality of blades are attached to a common shaft via gearing whereby the first and second sets of blades can travel at a speed approaching the speed of the fluid in the flow volume associated with each set of blades; each set of blades rotating at different rotational speeds, the gearing enabling an optimisation of relative blade velocity to the fluid velocity for each turbine assembly to maximise efficiency for a particular set of conditions. By utilising a synchronising gear-train, each pair of rotors at the ends of each set of blades move in unison.

Thus, for a given area through which there is a tidal or river current, the ability of a waterwheel to have sets of blades operable to be rotated at speeds generally corresponding to the actual flow speed of the water, enables the waterwheel to operate more efficiently.

Thus, for a given area through which there is a reliable source of wind energy, the ability of a turbine to have sets of blades operable to to be rotated at speeds generally corresponding to the actual flow speed of the wind, enables the turbine to operate more efficiently.

The waterwheel or turbine may be connected to an electricity generator, such as an alternator or dynamo. The waterwheel can be mechanically connected to the electrical generator. The waterwheel or turbine drives an output shaft which can transfer energy directly to an electrical generator or can be connected via a bevel gear assembly to provide rotational energy about an axis distinct from the rotor axis.

The present invention can operate with several sets of blades mounted upon rotors; three sets of blades can provide a reasonable degree of improvement in efficiency without providing unnecessary complication.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, reference will now be made, by way of example only, to the Figures as shown in the accompanying drawing sheets, wherein:-Figure 1 shows a waterwheel having three sets of blades of being mounted about a common axis; Figure 2 is a partial view of across three sets of blades of Figure 1; and, Figure 3 details how blades of the present invention enable connection to a common output shaft.

DETAILED DESCRIPTION OF THE INVENTION

In order to provide a better understanding of the present invention an embodiment of the invention will now be described. It will be apparent, however, to one skilled in the art, that the present invention may be practised without these specific details. This should not be construed to limit the present invention, but should be viewed merely as an example of a specific way in which the invention can be implemented. Well known features have not been described in detail so as not to obscure the present invention.

Referring now to Figure 3, there is shown a waterwheel with first and second positions of support, comprising first and second coaxial rotors at first and second sides, the two sets of rotors supporting two sets of blades. Central shaft 100 is mounted for rotation upon bearings 102 and is provided with gears 103 at first and second positions of support, the gears 103 being associated with meshing gears 111 connected to layshaft 108. Gears 109 & 110, at each side (or each position of support) are driven by the corresponding gears 121, 122 respectively associated with respective hubs 123, 124 of the rotors 35, 34, driven by blades 32, 31. Layshaft 108 is also mounted for rotation upon bearings (not shown) and gears 109 & 110 are fixed to the layshaft 108, for rotation therewith, whereby to transfer rotational energy via gear 111 to output shaft 100. This enables all rotor pairs 34 -34 and 35 -35 to move as one.

For clarity, if blade 31 on rotor 34 is subiect to different forces at areas indicated by arrows 126 & 127, the loads are resisted through the gear train and are not borne by blade 31 itself and both rotors at each end of the blade rotate in unison save for any stress and backlash factors. Without the resistive force of the gearing mechanism in water wheels, the blades would be subject to very high distributive loads. It will be appreciated that, in the case of an undercut waterwheel, the wider the blades are, then the greater the differences in forces that would be experienced.

Whilst Figure 3 shows a central drive shaft -and from which output drive can be obtained, at either or both ends -other types of drive can be employed. For example, the rotors may be mounted for separate rotation, without a central shaft, but can be linked by a number of alternative systems. For example, each side main bearing may drive a chain to an offset main shaft, preventing any disturbance a central shaft may provide. Pulleys may also be provided, but an indexing system with toothed belts would then be required. Equally, further gears could transfer output for rotation and synchronization, about an axis offset from axis of the rotors. A still further system could employ hydraulic fluids.

By having the two blades connected to a common output shaft through suitable gearing, the different sets of blades can rotate at different speeds relative to each other yet all contribute to rotation of a single output shaft. Moreover, the first and second rotors associated with each set of blades rotate at the same rotational speed, avoiding twisting and other forces which could otherwise prevent effective use of the turbine. Whilst the flow of water current through the waterwheel should be similar in cross-section, it will be realised, that the entry of blades into the water will affect water flow so that the extra turbulence will reduce current flow to an extent. However, suitable reduction in gearing will enable the innermost waterwheel to operate at a faster speed of rotation.

It will be realised that the blades must be shaped and dimensioned so as to allow passage of the moving blade, one with respect to the other and to the channel defined by the structure so that foreign bodies such as -in the case of a marine waterwheel -fish, seaweed, small stones and the like do not prevent movement. The shape of the blades need not necessarily be generally rectiplanar plates and may be generally cupped, for example, to maximise efficiency. Additionally, it may be prudent to have the blades arranged in a helical fashion, which in conjunction with an entry guide could reduce the problem of sea-weed in a marine waterwheel, but operating akin to a cylinder lawnmower.

In the case of a waterwheel, in order to maximise transfer of kinetic energy from the fluid flow, the blades will travel at a speed less than the speed of the fluid flow, since fluid flow energy is converted into rotational energy of the turbine, the smaller blades will operate at a greater rotational speed relative to the outermost blades.

It will also be realised that the principles of the undershot waterwheel can be transferred to derive energy from a flow of other fluid such as air, although it will be realised that the energy derivable from a wind-driven wheel of this "undershot configuration" would be less than that for a similarly sized water wheel.

The above description has been made with reference to an undershot waterwheel, where the axis of rotation is perpendicular to the water flow. It will be appreciated that the same principles can readily be extended to a fluid turbine, such as a wind turbine, where concentric sets of blades are arranged to rotate about an axis of rotation which corresponds with the fluid flow. It will be appreciated that a width of a blade in an undercut or cross flow water wheel will correspond to a length of a blade in an axial flow turbine.

Claims

CLAIMS1. A turbine, having at least two sets of blades for rotation about an axis of rotation across the turbine; wherein each set of blades is supported by first and second rotors at first and second positions of support of the turbine to define, in use, non-overlapping concentric paths; wherein, for each of the first and second positions of support, the rotors associated with each set of blades are coupled to an output shaft by gearing, the gearing enabling each set of blades and rotors to rotate at different rotational speeds whereby to compensate for a radial distance of said each set of blades to the rotational axis; and, wherein the output shafts of the first and second positions of support are mechanically connected by a mechanical connection whereby to ensure, in use, that first and second rotors of each set of blades rotate in unison about the said axis.
2. A turbine according to claim 1 wherein the turbine is a cross flow turbine, wherein the fluid flow is perpendicular to the axis of rotation of the turbine.
3. A turbine according to claim 1 wherein the turbine is an axial flow turbine, wherein the fluid flow is coaxial with the axis of rotation of the turbine.
4. A turbine according to any one of claims 1 -3, wherein the mechanical connection comprises a shaft connecting the output shafts of the first and second positions of support.
5. An undershot waterwheel according to claim 2, wherein the output shaft of the first and second positions of support comprise the same shaft.
6. A turbine according to any one of claims 1 -3, wherein the mechanical connection comprises a series of gears which mesh with an output shaft of each position of support, which drive a shaft offset and parallel to said axis of rotation.
7. A turbine according to any one of claims 1 -3, wherein the mechanical connection comprises a train of gears which enable the output shaft of a first position of support to mesh with the output shaft of the a second position of support.
8. A turbine according to any one of claims 1 -3, wherein the to mechanical connection comprises first and second sprockets connected by a continuous chain, which drive a shaft offset and parallel to said axis of rotation.
9. A turbine according to any one of claims 1 -3, wherein the mechanical connection comprises first and second sprockets connected by a continuous chain, which drive, via g0 drive systems with sprockets, a further chains to be employed in parallel with the axis of rotation.
10. A turbine according to any one of claims 1 -3, wherein the mechanical connection comprises first and second pulley wheels connected by a notched v-belt, which drive a shaft offset and parallel to said axis of rotation.
11. A turbine according to any one of claims 1 -3, wherein the mechanical connection comprises first and second pulleys connected by a continuous notched v-belt, which drive, via 900 drive systems with pulleys, a further notched v-belt to be employed in parallel with the axis of rotation.
12. A turbine according to any one of claims 1 -3, wherein the mechanical connection comprises first and second hydraulic drives which are linked so as to provide synchronous operation of respective first and second rotors of each set of blades.
13. An electrical generator comprising turbine in accordance of any one of claims 1 -12, wherein the turbine is connected, directly or indirectly, to an electrical generator.
14. An electrical generator in accordance with claim 13, wherein the electricity generator is one of an alternator or a dynamo.
15. A turbine in accordance with any one of claims 1 -14, wherein the number of sets of blades is between two and four.
16. A method of using turbine, having at least two sets of blades for rotation about an axis of rotation across the turbine; wherein each set of blades is supported by first and second rotors at first and second positions of support of the turbine to define, in use, non-overlapping concentric paths; wherein, for each of the first and second positions of support, the rotors associated with each set of blades are coupled to an output shaft by gearing, the gearing enabling each set of blades and rotors to rotate at different rotational speeds, whereby to compensate for a radial distance of said each set of blades to the rotational axis; and, wherein the output shafts of the first and second positions of support are mechanically connected for rotation; Said method comprising the steps of enabling a flow of fluid to bear against the respective blades of the turbine, causing respective first and second rotors of each blade to rotate, the gearing enabling rotors of each position of support to rotate, by virtue of the mechanical connection to ensure, in use, that first and second rotors of each set of blades rotate in unison about the said axis.
17. An apparatus substantially as described herein, with reference to any one or more of the accompanying Figures.s
18. The use of any one or more of the above apparatus substantially as described herein, with reference to any one or more of the accompanying Figures to generate rotational kinetic energy.
19. The use of any one or more of the above apparatus substantially as described herein, with reference to any one or more of the accompanying Figures to generate electricity.