GB2387880A - A liquid driven generator comprising a body which reciprocates in a liquid containing vessel - Google Patents

Abstract

A liquid-driven apparatus comprises a source 19 of liquid for driving the apparatus, a vertically disposed vessel 2, a means 6a for charging and discharging liquid from the source 19 into and out of the vessel 2 so as to cause the level of liquid to rise and fall in a cyclic manner, and a body 3 provided in a close fit with vessel 2 for vertical upward and downward movement in the vessel. A shaft or other connector is mounted on the body, the combination of the body and connector per se being such that when the body is submerged in said liquid there is net downward force on the combination. A force applying means 15 is operatively associated with the connector for applying a net upward force when the body 3 is submersed in said liquid but there is a net downward force on the combination when the body is not so submersed. There is a means for generating energy from the body 3 as it descends in the vessel 2 when discharged of liquid.

Description

1 2387880

LIQUID DRIVEN APPARATUS

The present invention relates to a liquid driven apparatus, for use in providing work or other form of energy.

The invention relates more particularly to such an apparatus in which a body is provided in an outer, vertical cylinder (or similar vessel) into and from which liquid is alternately (and repeatedly) charged and discharged so as to cause the body cyclically to rise and fall in the cylinder, useful work or other form of energy being derived during at least the downward movement of the body. Thus for example, the body may be arranged to drive a generator for the purposes of providing electricity.

Typically the liquid that is used to drive the engine is water obtained form a natural source thereof which provides a sufficient head of pressure to fill the cylinder and thus allow the body to rise in the cylinder prior to the water being discharged (e.g. to drain) to allow the body to descend with the generation of useful work or other desired form of energy. Such apparatus is of course particularly useful for generating work from a "free energy source", e.g. a natural body of water providing a suitable head of pressure, and finds particular (but not exclusive) applications in locations where electrical power is not readily available.

Various examples of such engines are already disclosed in the literature and many rely on the use of bodies which, if placed in a sufficient volume of water will naturally float. One example of such apparatus is disclosed in GB-A-2 231 368 (J.S.

Ferguson) in which the body is chargeable with the liquid (to contribute weight to the body) and has a wall structure which provides buoyancy for the body. One example of body disclosed in GB-A-2 231 368 has a wall structure comprised of inner and outer sheets of water-impervious plastics material with the intervening space (between the sheets) being filled with a low density material such as foamed plastics. In the preferred constructions of engine disclosed in GB-A-2 231 368 two such bodies are used each working within a respective cylinder and being mounted at opposite ends of a medially pivoted beam. In operation, the engine undergoes repeated cycles in which one cylinder is filled with liquid (e.g. water) whilst the other is exhausted thus

imparting a rocking movement to the beam from which work or other for of energy may be derived.

We have however found that for the engine disclosed in GB-A-2 231 368 there is a reduction in power generated as the float nears the top of its upward stroke, resulting in an overall reduction in performance of the device.

It is therefore an object of the present invention to obviate or mitigate the abovementioned disadvantage.

According to the present invention there is provided liquid-driven apparatus comprising (i) a source of liquid for driving the apparatus; (ii) a vertically disposed vessel connected to said source of liquid; (iii) means for charging and discharging liquid from said source into and out of said vessel so as to cause the level of said liquid therein to rise and fall in a cyclical manner; (iv) a body provided as a close fit in said vessel for vertical upward and downward movement therein; (v) a shaft or other connector mounted on the body, the combination of said somebody and connector per se being such that when the body is submerged in said liquid there is net downward force on the combination; (vi) force applying means operatively associated with said connector for applying to said combination a net upward force when the body is submersed in said liquid but with there being a net downward force on the combination when the body is not so submersed; and (vii) means for generating work or other form of energy from the body as it descends in the vessel when the latter is discharged of liquid.

Thus in accordance with the invention the body is caused cyclically to rise and fall in the liquid that is supplied to, and exhausted from, the vessel to drive the apparatus. In more detail, the body is associated with a connector, e.g. a shaft which

in turn is associated with the force applying means (vii) to which reference is made above. The combined weight of the connector and body is such that when the body is submerged in the liquid there is a net downward force on the combination (i.e. connector and body). Put simply, the body (with attached connector) "sinks".

Charging the vessel with liquid causes the combination of the body and the connector to undergo a sufficient loss of apparent weight that the combination is caused to rise by the force applying means which is capable of applying to the combination an upward force of sufficient magnitude to overcome the aforementioned net downward force on the combination so that the latter rises. Put another way, the density of the combination of the connector and the body becomes less than that of the liquid and the body rises. It will be appreciated that the magnitude of the upward force required is dependent on the apparent weight of the combination with the body immersed in liquid, thus being somewhat less than the absolute weight of the combination (i.e. its weight when the body is not immersed). Since the force applying means are not of themselves sufficient to raise the combination with the body is not submerged, draining of the vessel causes the combination to descend so that useful work may be generated during this downward movement.

Preferably the body has a density of 0.8 to 1.2, more preferably 0.9 to 1. 1, times that of the liquid. It is particularly preferred that the body has "neutral buoyancy" by which we mean that the density of the body is substantially equal to (e.g. 0.95 to 1.05 times) that of the liquid used for powering the apparatus.

Thus apparatus of the invention utilises a body (preferably a "neutrally buoyant" body) which may be of significant weight (in absolute terms) yet nevertheless appears to have a considerably reduced weight when submersed in the liquid that is used to drive the apparatus. Thus the body can be caused to rise relatively easy in said liquid by a low force provided by the force generating means so as to move to its uppermost position. However once the liquid is removed from the vessel, the relatively large absolute weight of the body causes the latter to descend under gravity with considerable force and generate useful work.

The liquid used for driving the apparatus is preferably water. The water should be supplied from a source thereof which provides a sufficient head of pressure to allow the vessel to be filled ideally without the need for supplementary pumping which would reduce the overall energy generating efficiency of the apparatus. The water source may for example be a river, stream, lake or other natural body of water.

We do not however preclude the possibility that some other liquid may be used for driving the apparatus.

If the liquid driving the apparatus is water then the body most preferably has a density of O.9S-1.05 g cm3. Most conveniently the body comprises a water-filled, solid walled shell of a plastics material having a density of O.9S g cm3 to l.OS g emu, preferably 1 g cm3. The wall thickness of the shell will be dependent on the nature of the plastics material and/or overall size of the body, although should be the minimum possible taking these factors into account. The material of the shell may be rigid or flexible. If thin and flexible then the body may, if necessary, be pressurised.

Conveniently the shell comprises polypropylene (having a density of about 1 g cm3).

The means for deriving work or other form of energy from the downward movement of the body may for example be an electrical generator (e.g. a dynamo), e.g. driven during downward movement of the body by an appropriate mechanical connection. Altematively the energy may be provided by a turbine driven by discharge of liquid from the vessel.

The means for applying a force to assist rising movement of the body (when submersed in the liquid) may take a number of forms. In one preferred embodiment of the invention there is used a counterweight associated with the body in such a way that once the body is surrounded by sufficient liquid, the counterweight is able to move downwardly by means of gravity with an upward force then being applied to the body to assist rising movement thereof.

Conveniently, the counterweight is mounted on one run of a vertically disposed endless chain, belt or the like positioned above the vessel in which the body

s is provided, and the body is mounted on a shaft which in turn is directly or indirectly connected to the other run of the vertically disposed chain, belt or the like. Once sufficient water has been introduced into the vessel, the counterweight is able to move downwards under gravity so as to drive the chain, belt or the like such that an upward force is applied to the body to cause it to rise in its vessel.

The endless chain, belt or the like may be arranged to drive an electrical generator to provide electricity as the energy derived from the downward movement of the body. The apparatus may be such that the generator is only driven during the downward movement of the body. In a preferred embodiment of the invention, at least the apparatus are provided and arranged to operate in tandem so that the generator is continuously driven.

In an advantageous embodiment of the invention, the body is associated with a piston or the like which works within a cylinder that is coaxial with the vessel in which the body is provided but separated therefrom in a liquid type manner. Means are provided to enable said cylinder to be charged with liquid when the piston is at its upper position. With the cylinder so-charged with liquid, the body is retained at its upper position even when the liquid surrounding the body is drained from the vessel.

The body moves downwardly when liquid is discharged from the cylinder. This discharged liquid may be used to drive means (e.g. a turbine) for providing energy.

This energy may be additional or alternative to that provided by an electrical generator which is mechanically coupled to the body as described above.

The invention will be further described by way of example only with reference to the accompanying drawings, in which: Fig 1 is a part cutaway elevation of a first embodiment of apparatus in accordance with the invention; Fig 2 is a view (to a reduced scale) of the apparatus of Fig 1 looking in the direction of arrow A thereof;

Fig 3 schematically illustrates To apparatus of the type shown in Figs 1 operating in tandem; Fig 4 illustrates a second embodiment of the invention; Fig 5 illustrates the water supply arrangement for the apparatus illustrated in Fig 4; Fig 6 illustrated a third embodiment of apparatus in accordance with the invention; and Fig 7 illustrates a water supply arrangement for the apparatus of Fig 6.

Fig 1 illustrates details of a water-driven apparatus 1 we have constructed for generating electricity. The apparatus 1 comprises a cylinder 2 in which is provided a body 3 mounted on a shaft 4. The vessel 2 has a lower inlet/outlet port 5 connected to a pipe 6 which is associated with a three-way valve 6a.

Body 3 is comprised of a water-filled polypropylene shell, the polypropylene having a density of about 1 g cm3. The body 3 is a relatively close fit within the cylinder 2 with there being a small clearance between the outer surface of the body 3 and the inner surface of cylinder 2 which provides sufficient clearance to avoid unwanted capillary effects and/or undue manufacturing tolerances.

Provided above the vessel 2 (on an appertured cover 7 thereof) is a frame 8 provided with upper and lower rotary shafts 9 and 10 respectively on which are mounted sprocket wheels 11 and 12. The mounting of sprocket wheels 11 and 12 on their shafts 9 and 10 is by means of a ratchet arrangement (not shown) whereby anti-

clockwise rotation of sprocket wheels 11 and 12 (as viewed in Fig 1) effects corresponding anti-clockwise rotation of shafts 9 and 10 whereas with sprockets 11 and 12 rotating clockwise they "free wheel" on their respective shafts and do not effect rotation thereof.

A vertically disposed, endless drive chain 13 extends around the sprocket wheels 11 and 12. To one run of the chain 13 is attached an arm 14 which is fixed to the upper end of the shaft 4. Provided on the other run of the drive chain 13 is a counterweight 15. The arrangement of arm 14 and the counterweight 15 is such that the arm is in the its lower most position when the counterweight 15 is in its uppermost position (see Fig 1) and vice versa. The weight of the counterweight is such that with the body 3 immersed in water, the counterweight is able to descend and cause the body 3 to rise.

By way of example, the body 3 may be generally cylindrical and have a height of 500mm, diameter of 300mm, a wall thickness of 2.5mm, and a weight (when filled with water) of 30kg. The cylinder 2 may have a height of lOOOmm and an inner diameter of 315mm. The shaft 4 may have a weight of lkg and the counterweight 15 may have a weight of 4kg.

An electricity generator 16 is provided for operation by rotation of the lowermost rotary shaft 10. The- frame 8 is further provided with upper and lower microswitches 17 and 18 respectively that are actuated by the block 16 and are operatively connected to valve 6a by a control arrangement (not shown) for the purposes to be described.

The three-way valve 6a serves to connect the vessel 2 selectively either to a head of water referenced for convenience by the numeral 19 or to a drain referenced as 20. Conveniently the head of water is provided by a natural body such as a lake, river or the like.

In the condition illustrated in Fig l, the vessel 2 is being charged with water from the supply 19 (for which purpose valve 6a is in the appropriate position to allow water from that supply to pass along pipe 6 and through port 5. As the water level in vessel 2 rises, the body 3 becomes immersed in water. As a result the counterweight

15 is now able to descend under gravity and assist the body 3 (with its attached shaft 4) to rise.

As the body rises, sprocket wheels 11 and 12 are caused to rotate in a clockwise (as viewed in Fig 1) direction but because of the aforementioned ratchet arrangement they (i.e. the sprocket wheels) do not act to effect rotation of shafts 9 and 10. Water continues to fill the vessel 2 until the body 3 has risen to a point such that the arm 14 actuates microswitch 17. At this point, the valve 6a is switched so that water from vessel 2 passes to drain 19.

With vessel 2 being exhausted of liquid, body 3 is able to move downwardly under gravity thus causing counterweight 15 to move back to its uppermost position.

The torque to be "extracted" from shaft 10 at least partially determines the rate at which body 3 descends. During the downward movement of the body 3, the sprocket wheels 11 and 12 are rotated anticlockwise (as viewed in Fig 1) and effect rotation of shafts 9 and 10, the latter serving to drive the generator 16 to produce electricity. It is possible, for example, for the descent of the body 3 to be relatively slow so that it is not immersed in liquid at all during at least part of its descent.

It will be appreciated from the above description that the apparatus as

described only drives the generator 16 during the downward movement of body 3. It is however possible to have two apparatus of the type described for Fig 1 operating side-by-side with their sprocket wheels 12 mounted on a common shaft 10. Such an arrangement schematically illustrated in Fig 3 in which the common shaft 10 drives a flywheel 21 connected to gear box 22 and generator 23. The two apparatus 1 are arranged to operate 180 out of phase with each other such that when the body 3 of one apparatus is at its uppermost position the body 3 of the other apparatus is at its lowermost position. Thus as one body 3 rises (so that its associated sprocket wheel 12 does not contribute to rotation of shaft 10) the other body is descending to effect

rotation of shaft 10 and drive the flywheel 21. Consequently with such an arrangement the drive to the generator 23 is continuous.

Reference is now made to the apparatus 101 illustrated in Fig 4 of the drawings which comprises upper and lower coaxial cylinders 102 and 104, the interiors of which are separated from each other by a divider arrangement 105.

Provided in the upper cylinder 102 is a body 103 (similar to the body 3 as described for Fig 1) mounted on a vertical shaft 106 which, on the one hand, extends downwardly through a central basal aperture (provided with a liquid tight seal 107) of the vessel 102 and, on the other hand, upwardly out of the top of vessel 102. At the lower end of shaft 106 is a piston-type arrangement 108 which incorporates a flexible seal 109 slideable on the inner surface of cylinder 104 Divider arrangement 105 incorporates air passageways 110 and spaced pins l l l which allow air flow in the direction of the double headed arrows either into or out of the vessel 104 depending on the direction movement of piston 108.

Although not illustrated in Fig 4, the upper end of shaft 106 is associated with a similar arrangement of components 9-15, 17 and 18 as illustrated in Fig 1 of the drawings for raising the body 103 when vessel 102 is charged with liquid. In the present embodiment, there is not a generator 16.

Referring now to Fig 5 it will be seen that there are two reservoirs 113 and 114 which are illustrated schematically and, in practice, would be at higher levels than depicted.. Reservoir 1 13 has an inlet 1 15 connected to a natural head of water and has an outlet 1 16 associated with a threeway valve 1 17 which, in one position allows water to be supplied from reservoir 113 to vessel 102 via its inlet/outlet port 118 and, in another position, allows water to be supplied from vessel 102 to reservoir 114. This latter reservoir has an outlet 119 connected via a valve 120 to an inlet port 121 of vessel 104. The vessel 104 has an outlet 122 connected via a valve 123 to a line 124

in which is provided a turbine arrangement 125. Additionally vessel 102 has an outlet 126 connected via a valve 127 to the line 124.

Assume initially that reservoirs 113 and 114 are both charged with water and that all valves are closed. To operate the apparatus, valve 117 is operated to allow water from reservoir 113 to enter the vessel 102 and simultaneously valve 120 is operated to provide for filing of vessel 104. As a result, the body 103 rises in exactly the same way as described for the apparatus of Fig 1, i.e. with the assistance of the counterweight (not illustrated in Figs 4 and 5). This rising movement of the body also causes the piston 108 to be raised to an upper position, with air from behind the piston 108 being exhausted via the ports 110 and spaces between the pins 111.

Valve 120 is then closed and valve 117 moved to a position to allow vessel 102 to drain into reservoir 114. The body 103 is however retained at its upper position due to the water (to the level of piston 108) in the vessel 104.

Valve 117 is then closed to allow reservoir 113 to be replenished.

Valve 123 can now be open so that, with downward movement of the body 103, water is forced from vessel 104 through turbine 125 to generate electricity.

Valve 123 is subsequently closed and the cycle may then be repeated.

It will be appreciated that two of the apparatus may be coupled together to work in tandem so as to provide for continuous operation of the turbine 125.

Normally the valve 127 remains closed through the entire cycle of operation of the apparatus 101 so that water originally contained in vessel 102 may be used to charge reservoir 114 which in turn supplies vessel 104. In certain circumstances however valve 127 may be opened to allow vessel 102 to be emptied via valve 127 should this be necessary.

Reference is now made to Fig 6 which illustrates a third embodiment of the invention. In many respects, the apparatus 200 of Fig 6 is similar to that illustrated for Fig 4 save for that the body 203 (equivalent to body 3 and 103) is provided in a lower vessel 202 and the piston 208 (equivalent to piston 108) with its seal 209 is provided in an upper vessel 204.

Body 203 is mounted on a shaft 205 associated with the same arrangement of components 8 to 15, 17 and 18 as illustrated in Fig 1 (but not shown in Fig 6) for the purposes of raising body 203 when vessel 202 is charged with water. Thus, the apparatus of Fig 6 does not include a generator 15.

Vessels 202 and 204 have water inlets 210 and 211 respectively and have water outlets 212 and 213 respectively. Vessel 202 has facility 214 to allow air to enter into, or be discharged from, vessel 102 as necessary. Similarly vessel 204 has a facility 215 to allow air to enter into, or be exhausted from vessel 204. The facilities 214 and 215 may, for example be ports or may be valves.

Reference is now made to Fig 7 showing the water supply arrangement for the apparatus of Fig 6.

The operation of the arrangement shown in Fig 7 will now be described on the basis that all valves are initially closed and reservoirs 216 and 218 are charged with water. Valves 217 and 219 are switched to a position to allow vessels 202 and 204 to be filled with water from reservoirs 216 and 218 respectively.

As a result, body 203 rises in exactly the same way as described for bodies 3 and 103. This rising movement of the body 203 also causes the piston 208 to be raised to an upper position.

Valves 217 and 219 are now closed.

Valve 220 is now opened to allow water to drain from vessel 202. The water discharge may be passed through turbine 221. Valve 220 is then closed.

It will be appreciated that body 203 is still at its upper position due to the presence of water in vessel 204.

Valve 222 is now opened to allow body 203 to descend under gravity and the water in vessel 204 to be forced through the turbine 221.

As with the embodiment of Figs 4 and 5, electricity is generated during the downward stroke of the body 203 by operation of the generator 16. As with previous embodiments, it will be appreciated that more than one apparatus 201 may operate in tandem so that there is continuous operation of turbine 221.

Claims (18)

1. A liquid-driven apparatus comprising (i) a source of liquid for driving the apparatus; (ii) a vertically disposed vessel connected to said source of liquid; (iii) means for charging and discharging liquid from said source into and out of said vessel so as to cause the level of said liquid therein to rise and fall in a cyclical manner; (iv) a body provided as a close fit in said vessel for vertical upward and downward movement therein; (v) a shaft or other connector mounted on the body, the combination of said shaft body and connector per se being such that when the body is submerged in said liquid there is net downward force on the combination; (vi) force applying means operatively associated with said connector for applying to said combination a net upward force when the body is submersed in said liquid but with there being a net downward force on the combination when the body is not so submersed, and (vii) means for generating work or other from of energy form the body as it descends in the vessel when the latter is discharged of liquid.

2. Apparatus as claimed in claim 1 wherein the body has a density of 0.8 to 1.2 times that of the liquid.

3. Apparatus as claimed in claim 2 wherein the body has a density of 0.9 to l.l times that of the liquid.

4. Apparatus as claimed in claim 3 wherein the body has neutral buoyancy in the liquid.

5. Apparatus as claimed in claim 1 wherein the liquid used for driving the apparatus is water.

6. Apparatus as claimed in claim 5 wherein the water is supplied from a natural source thereof.

7. Apparatus as claimed in claim 6 wherein said source is a river, stream, lake or other natural body of water.

8. Apparatus as claimed in any one of claims 5 to 7 wherein the body has a density of 0.95 to 1.05 g cm3.

9. Apparatus as claimed in claim 8 wherein the body comprises a waterfilled, solid walled shell of a plastics material having a density of 0. 95 to 1.05 g cm3.

10. Apparatus as claimed in claim 9 wherein the shell comprises polypropylene having a density of about 1 g cm3.

11. Apparatus as claimed in any one of claims 1 to 10 wherein the means for deriving work or other form of energy from the downward movement of the body is an electrical generator.

12. Apparatus as claimed in any one of claims 1 to 11 wherein the means for deriving work or other form of energy from the downward movement of the body comprises a turbine.

13. Apparatus as claimed in any of claims 1 to 11 wherein the means for applying a force to assist rising movement of the body comprises a counterweight.

14. Apparatus as claimed in claim 13 wherein the counterweight is associated with the body wherein the counterweight is mounted on one run of a vertically disposed endless chain, belt or the like positioned above the vessel in which the body is provided, and the connector is directly or indirectly connected to the other run of the vertically disposed chain belt or the like.

IS. Apparatus as claimed in any one of claims 1 to 14 wherein the body is associated with a piston or the like which works within a cylinder that is coaxial with the vessel in which the body is provided but separated therefrom in a liquid type manner, means being provided to enable said cylinder to be charged with liquid when the piston is at its upper position to retain the body at its upper position when the vessel in which it is provided has been drained of liquid, and means also being provided to derive energy from discharge of the liquid in the cylinder as the body moves downwardly.

16. Apparatus as claimed in claim 15 wherein said means for deriving energy from liquid discharged from the cylinder is a turbine.

17. Apparatus as claimed in claim 16 wherein liquid discharged from the vessel in which the body is provided may also be used to drive said turbine.

18. Liquid driven apparatus substantially as herein before described with reference to Figs 1 and 2, or Fig 3 or Figs 4 and 5 or Figs 6 and 7 of the accompanying drawings.