WO1997047877A1

WO1997047877A1 - Hydraulic buoyancy engine

Info

Publication number: WO1997047877A1
Application number: PCT/GB1997/001623
Authority: WO
Inventors: Alister Ure Reid
Original assignee: Alister Ure Reid
Priority date: 1996-06-14
Filing date: 1997-06-16
Publication date: 1997-12-18
Also published as: GB9612532D0; AU3101397A

Abstract

The present invention relates to an engine (9) comprising a chamber (13), a float (12) reciprocable in the chamber (13), supply means (34) for supplying a liquid to the chamber (13) from a head of liquid, outlet means (35) for receiving liquid from the chamber (13), inlet valve means (11) for controlling the flow of liquid into the chamber (13), outlet valve means (10) for controlling flow of liquid out of the chamber and power output means (78) connected to the float (12) to convert motion of the float to a power output for the engine (9). In use of the engine (9), the inlet (11) and outlet (10) valve means respectively and successively admits liquid into the chamber (13) from the supply means (34) and allows flow of liquid out of the chamber (13) to the outlet means (35) in order to cause the float (12) to reciprocate in the chamber (13). The present invention provides: an improved control mechanism for controlling opening and closing of the inlet (11) and outlet (10) valve means; an improved power output means with a rotatable shaft driven to rotate in one sense only; improved power output means with a hydraulic piston and cylinder arrangement; a method of manufacture and installation of the engine (9); an engine (9) with an integral discharge surge compartment; an engine (9) with removable inlet (11) and outlet (10) valve means; an engine (9) with a linear generator (1000); and an engine with seals of hollow cross section.

Description

HYDRAULIC BUOYANCYENGINE

The present invention relates to an engine of the kind having a float reciprocable vertically in a chamber, means to supply liquid to the chamber from a head of liquid to raise the float and means to allow the water to exhaust from the chamber to lower the float. Such an engine is typically a water engine.

An early example of water engine can be found in GB-A-1484721. The water engine described in this specification is designed to be constructed on a relatively large scale; the example is given with a chamber measuring 150 ft and 40 ft wide. The specification also discloses use of a concrete float weighing 500 tonnes. In the specification, there is described use of the water engine to extract energy in a tidal barrage scheme or in a low head run-off-river scheme, say 5 ft head or less. In all embodiments shown the power take off mechanism requires a rack mounted on the top of the float, which engages a quadrant gear. In all embodiments the power output mechanism is designed to provide reciprocating vertical motion, which can be used, for instance, to drive a piston in a water pump.

GB-A-1517643 discloses a further water engine of large scale: the embodiment described has a piston of a diameter of 20 feet. The output from the engine is a hydraulic output in the form of fluid pressurised by a ram.

A development of the water engine is described in GB-B-2138509. This water engine has at least two floats and chambers and the power output mechanism comprises a pivotally mounted beam which is connected to two separate floats so that the beam oscillates with motion of the floats. The engine described is designed to be constructed on quite a large scale, as a barrier in a water channel. The power take off provided to the engine is hydraulic power take off, the oscillating beam of the engine compressing water or other fluid in two hydraulic rams.

EP-B-0 058 542 shows a further large scale water engine with a power take-off which provides compressed hydraulic fluid and with a gate valve operating mechanism which uses a hydraulic ram to open and close the gate valves.

The present invention provides in various different aspects engines as described in the claims 1, 19, 31, 36, 49, 52, 56 and 60 attached, methods of and use of engines as described in claims 44 and 57 and methods of manufacture and installation as claimed in claims 38 and 47. Preferred features of the engines and the method are given in the dependent claims.

Preferred embodiments of the present invention will now be described with reference to the accompanying drawings, in which:

Figure 1 is a schematic drawing of a first embodiment of water engine;

Figures 2 and 3 are detail views of the water engine of Figure 1;

Figure 4 is a plan view of the water engine of Figure 1 in use connected to receive water from and output water to a stream; Figures 5a and 5b are detail views of the water engine of Figure 1;

Figure 6 is a side view of the water engine of Figure 1; Figure 7 is a plan view of the water engine of Figure 1;

Figures 8a) , b) and c) are detail views of the water engine of Figure 1;

Figure 9 is an exploded view showing the components of the water engine of Figure 1;

Figures 10, 11, 12, 13,14 a) ,b) and c) and 15a), b) and c) illustrate the construction and operation of gate valves of the water engine of Figure l;

Figures 16, 17, 18, 19, 20 , 21, 22, 23a) and 23b) illustrate a control mechanism for controlling the gate valves of the water engine of Figure 1;

Figure 24 illustrates an adjustment mechanism in a power output drivetrain of the water engine cf Figure 1; Figures 25, 26 and 27 illustrate a first embodiment of power output drivetrain of the water engine of Figure 1;

Figures 28, 29a) and 29b) illustrate a second embodiment of power output drivetrain of the water engine of Figure 1;

Figures 30, 31a) and 31b) illustrate a third embodiment of power output drivetrain of the water engine of Figure 1;

Figures 32 and 33 show graphically variation in length of a lever arm in the power output drivetrains of Figures 28, 29a), 29b), 30, 31a) and 31b);

Figures 34a, 34b, 34c, 35a, 35b, 35c and 36 show a modification to the control mechanism for controlling the gate valves which is illustrated in Figures 16, 17, 18, 19, 20, 21, 22, 23a) and 23b); Figure 37 shows a cross-section of a fourth embodiment of power output drivetrain of the water engine of Figure 1 in a first position, taken along the line A-A of Figure 39 in the direction of the arrows;

Figure 38 shows the same cross-section as Figure 37 but with the power output drivetrain in a second position;

Figure 39 is a plan view of the power output drivetrain of Figure 37 in the position of Figure 37; and

Figure 40 is a plan view of the power output drivetrain of Figure 38 in the position of Figure 38;

Figure 41 is a detail view of a water engine; Figures 42, 43, 44, 45, 46, 47, 48, 49a), 49b) are schematic views of a further embodiment of water engine;

Figures 50, 51, 52, 53, 54, 55 are schematic views of an additional embodiment of water engine; Figure 56 is a schematic view of a simplified gate valve control mechanism; and

Figure 57 is a schematic view of an engine with a linear generator. The operation and construction of water engines according to the invention will now be discussed. The general principle of operation of a water engine 9 is that the opening and closing of two gate valves 10 and 11 (see Figure 1) causes a float 12 to rise and fall in a float chamber 13 which actuates a quadrant gear

14 and two (fixed but adjustable) crank arms ( 15 only shown in figure 1) linked to an output drive mechanism. For a flow of water of 0.03 cumecs the stroke time for the float 12 will be about 2 seconds. Such a flow is available from a small stream. 100% of the energy in the flow of water through the engine 9 at the stated operating head is available for extraction because the height of the float 12 is at least twice the design operating head and the float 12 is ballasted to float at half the height of the float 12. In accordance with the Principle of Archimedes, the force exerted on the quadrant gear 14 by the float 12 reduces to zero while the float 12 descends into or rises out of the water in the chamber 13 but this reducing force is converted into a steady force acting alternately on the output power mechanism, because the effective lever arm of the rod connecting the crank arm 15 to the output mechanism also reduces to zero during each power output stroke as illustrated by Figures 32 and 33.

The water engine 9 can be moved from site to site or delivered as a package for assembly and installation at a permanent site. Accordingly, the engine 9 is to be fabricated in four main parts, (or any other suitable number of integers) light enough to be easily carried by hand from site to site and then assembled and strong enough to withstand rough handling in transit. They must be able to resist pressures when installed in the ground.

Figure 5a shows the float 12 in the float chamber 13 with three guide strips 17, 18, 19 or blocks to maintain the gap between the float 12 and the chamber wall. The interaction of a rack 20 attached to the float 9 and the quadrant gear 14 produces a reaction force between the float 12 and the chamber wall directly opposite the rack/quadrant gear. The guide block 18 at this location is shown in Figure 5b moving in a guide channel 21 to prevent rotation of the float 12 about the axis of the float 12, which would otherwise cause the rack 20 and the quadrant gear 14 to disengage. If this arrangement and the forces acting thereon cause excess friction between the guide blocks and the guide channel then rollers or wheels can be mounted above and below the float.

The four major parts of the engine 9 (i.e. the base unit 22, the float chamber housing 23, the power take off unit 24 and the intake surge chamber 25) are shown in Figure 7. Figures 8a and 8b show lug fittings 26 as a means to fix the float chamber housing 23 to the base unit 22 without the need for nuts and bolts which can be lost in transit. After being turned into the fixed position, the float chamber housing 23 is secured at the top with a strap 27 bolted at one side of the power take off unit (see Figure 6) and fastened to a ring 28 fixed at the other side of the power take off unit 24 and the strap adjustment 29 is then tightened. In transit the strap 27 is secured to a second ring fixing 30. The float chamber housing 23 is connected to the base unit 22 by means of lugs 998 and 997 engaging suitable recesses defined in the base unit 22 as shown in Figure 8c. A plan view of the engine 9 with the surge chamber 25 detached is shown in Figure 9.

In assessing the overall height for the engine 9 the starting point is the assumed water level in the stream at the point where the intake is to be placed, referred to as the upstream (U/S) water level. The engine as shown is designed to operate where the water level in the stream at the discharge pipe (the downstream (D/S) water level) is 0.5m below the U/S water level. The upstream water level is to be marked permanently on the side of the float chamber housing 23 as a reference mark 999 for men when setting the engine in position at the side of a stream; a stream 31 is shown in Figures 1 and 4.

Variation in the water levels is not critical to the working of the engine. The engine 9 will continue to work at various heads within limits, but the operating efficiency and the output power is dependent on the head and flow of water that is available at any particular time.

Figure 3 shows the float 12 with dimensions at 0.5m diameter and lm high and ballasted to float when freely immersed in water at 0.5m above the base. In this condition, the float 12 is shown with the mid point of the height at the line of the U/S water level. The diameter of the float chamber 13 is selected to provide a gap round the float 12 of about 10 mm or a gap sufficiently wide to accommodate the guide blocks 17,18,19 attached to the side of the float 12.

The design stroke for the float 12 is 0.5m so that the height of the float chamber 13 is 1.5m plus an allowance for overshoot before the float 12 hits a stop 32 attached to the underside of a cover 33 to the float chamber 13. Thus the top of the float chamber 13 above the top water level is 0.5m plus the overshoot distance plus the stop.

The rack 20 fixed to the side of the float 12 connected to the float 12 (or via a cable connection) engages with the teeth cut in the quadrant gear 14 which is mounted in the power take off unit 24. The quadrant gear 14 turns through a design angle of 60 degrees during a float stroke of 0.5m and the effective radius of the quadrant gear is 0.47m. With allowances for overshoot up and down of the float 12, the quadrant gear 14 should provide for a turn of say 80 degrees (60 degrees plus 10 degrees at the end of the upstroke and the down stroke) otherwise the quadrant gear 14 would disengage from the rack 20 during an overshoot.

In order to achieve the changing geometry of the headgear already mentioned above, it is essential that the float 12, the rack 20, the quadrant gear 14 and output power mechanism are set and remain in the correct relative positions during each stroke of the float 12 without any disengagement.

The height of the base unit 22 is determined by the space required for the gate valves 10 and 11. The overall length of the base unit 22 is dependent on the space required for the power take off mechanism housing 24, the float chamber housing 23, and the intake gate valve 11.

The intake surge chamber 25 has a push fit joint with the base unit 22 and suitable fixings are provided the float chamber housing 23 and power take off housing 24 which are fixed on top of the base unit 22.

All moving parts are to be designed for continuous working over long periods measured in years with minimal maintenance. In particular, the gate valve bearings and other bearings in the gate valve operating mechanism must be able to work in dirty water or water with suspended sediments or other abrasive material. Consideration should be given to the use of tufnol bearings or other similar materials and the bearings should be designed for ease of replacement.

Mild steel is to be avoided if possible in the fabrication of the engine.

Studs and other projections from the structure are to be avoided because of possible damage during storage and transit when used as a moveable power source.

Tolerances for the float 12 and chamber 13 walls and the overall dimensions of the engine are not critical.

Good robust engineering joints between the four main parts of the engine are required but absolute water tightness at the joints is not essential.

A supply pipe 34 and a discharge pipe 35 with minimum diameters of 250 mm are push-fitted at the intake surge chamber 25 and at an output surge chamber 94 the base unit 22. Spigot and socket joints are not required. Extra ports in the base unit 22 and surge chamber 25 (to provide for supply and discharge pipes in all directions) , are to be fitted with blank covers (e.g. 36, 37, 38, 39, see Figure 4).

The power take off mechanism is connected to an output electrical generator rated at lOOw. The details of the gate valves 10 and 11 are shown in Figures 10 to 15. Each gate valve 10, 11 is a plate of robust firm plastic or similar light material fixed to an axle 40, 41 mounted on bearings attached to a stiff frame 42A and 42B that is inserted, complete and ready for use, through the top of the base unit 22 and secured in position. Detachable gate covers 991 and 992 are provided to permit this (see Figure 9) . Crank arms 43, 44 are fitted to the gate valves 10, 11 as part of the mechanisms to open and close the valves 10, 11. The effective gate valve opening is 250mm x 600mm (see Figure 15) but the gate will be wider at say 300mm to allow the gate valves to make contact with side seals 45, 46, 47, 48 and with upper and lower seals 200, 201, 202, 203.

There are two saddle fixings over the axles 40, 41 for each gate valve 10, 11 in addition to the crank arm fixings on the gate valves 10,11 at approximately the centre of the gate opening.

Each upper and lower water seal 200, 201, 202, 203 is formed (see Figures 14 a) , b) , c) with a strip of rubber 49 or similar material folded along the long dimension and held in position with a keeper plate 50 fixed to a gate jamb 51 such that a tube is offered for contact with the gate 10 when in the closed position.

The edges of the gate jamb plate 51 and the keeper plate 50 are rounded where there is contact with the rubber 49 to avoid wear and tear, see Figure 14c) .

Instead of the arrangement of Figures 14a) , 14b) , 14c) an arrangement as shown in Figure 41 can be used where a rubber strip 300 with a predefined cross- section is used instead of the strip of folded rubber 49. The strip 300 has a hollow cross-section to allow for compliance of the strip 300.

The gate valve seals 45, 46, 47, 48, 200, 201, 202, 203 are set before the frame assembly 42A, 42B is placed in position in the base unit 22. With each gate valve 10, 11 held firmly in the vertical position in the frame, each section of water seal 200, 201, 202, 203 is eased forward under a loosened keeper plate (e.g. 50) until the arc shape of the rubber strip 49 or 300 is then tightened down to hold the strip 49 firmly in place. There are eight points where there is discontinuity of seal, two points at each end bearing and at each of the four corners of the gate valve 10, 11 where extra attention should be made to minimise the leakage.

After the gate valves 10, 11 have been placed in position and connected up, the length of a rod 52 (see Figure 10) connecting the push/pull operating mechanism in the headgear to the D/S gate valve 10 and a rod 53 connecting the two gate valves 10, 11 are adjusted so that each gate valve 10, 11 is in the closed position respectively when the rod 52 is in its uppermost and lowermost positions. A manually operated adjustment mechanism 89 is shown in Figure 10.

The stroke of the rod 52 in the gate operating mechanism and the radii of the crank arms 43, 44 are designed to turn the gate valves through 90 degrees. It is important that the adjustment procedure does not bring either closed gate valve into contact with the keeper plates 50 holding the rubber strips 49, 300 and the water seals 45, 46, 47, 48, 200, 201, 202, 203 in position. With the push/pull rod 52 at the end of the travel both up and down, the closed gate valve 10, 11 should cause the arc of the rubber strip (49, 300) to deform to the same extent as when the seal 45, 46, 47, 48, 200, 201, 202, 203 were originally set in position, otherwise the constant slamming shut of the gate valve 10, 11 against the water seals 45, 46, 47, 48 would cause damage to the rubber strips and the keeper plate fixings.

The holes for the fixing bolts in axle blocks 54, 55 and the gate valve plates 10, 11 are to be elongated so that each axle 40, 41 can be raised above the centre line of the gate opening (downstream gate valve) or lowered (upstream gate valve)to provide excess area of gate on the side of the axle 40, 41 that tends to keep the gate in the closed position when water pressure is applied, see the offset illustrated in figures 15b) and 15c) . The final settings will be determined by trial and error.

The rod 52 connecting the push/pull mechanism and the D/S gate valve 10 is 'hooked' to avoid contact with the gate valve 10 when in the open position.

The engine has a gate change over mechanism shown in Figures 16 to 24. The rod 52 shown in figures 10 and 11 is pivotally mounted on a block 56 (see Figure 23a) ) which is fixed to a rod 57 that is rectangular in cross-section (see figure 23b) ) The rod 57 is rectangular to prevent any turn about the axis of the rod 57. The rod 57 is constrained to move up and down because it passes through the two bearing blocks 58 and 59 set vertically apart and the spacing of the bearing blocks 58 and 59 determines the maximum stroke of the rod 57 and thus the stroke available to operate the gate valves 10 and 11.

The timing of the stroke of the rod 52 is controlled by the position of a control island 60 during the stroke of the float 12. This island 60 is made up of two parts 60A and 60B (see Figure 18) ,respectively mounted on sectors 61, 62 which can be rotated relative to each other about the axle of the quadrant gear 14 before being fixed in position by fixing bolts 63, 64 projecting from the side of the quadrant gear 14. The two parts 60A, 60B of the control island 60 must be able to "telescope¹ while being adjusted for the correct position so as to present a continuous inner and outer arc.

The two sections 60A and 60B are fixed relative to the quadrant gear 14 in use in order to ensure correct opening and closing of the gate valves 10, 11. A follower arm 65 is connected to a block 66 mounted on the rod 57 (see figure 23a)) so that the rod 57 moves with the follower arm 65.

The operation of the mechanism will now be described. When the follower arm 65 is at point "A', see figure 18, the follower 65 drops down vertically under the action of a counterweight 67 attached to the block 66 (see Figures 16 and 17) and this action closes the up stream gate valve 11 and opens the down stream valve 10. At this point, the float 12 starts the down stroke and the side of the control island "AB' (see Figure 18) is not radial to allow the float 12 to start this movement.

During the down stroke of the float 12 the quadrant gear 14 turns in a clockwise direction and the follower 65 is held in the down position during the stroke because the control island 60 prevents any upward movement of the follower 65 during the stroke. When point ~C on the island is reached the follower is free to rise up to the point ~D' under the action of the energy stored in a spring 68 which connects the top of the rod 57 to the quadrant gear 14, The spring 68 is fully extended by the movement of the quadrant gear 14 during the down stroke of the float 12.

The release of the stored energy in the spring 68 lifts the follower 65 which closes the down stream gate valve 10 and opens the up stream valve 11. the side of the control island "CD' is not radial so that the float 12 is able to start the upstroke immediately after the gate valve change over. The inner arc "DA¹ of the control island 60 prevents the follower 65 and the control rod 57 from moving in a downwards direction during the upstroke of the float 12 and the anti-clockwise movement of the quadrant gear 14.

The counterweight 67 is sufficient to act against the spring 68 in a partially extended condition and to change the gates over with a smooth and crisp action. The spring 68 must be strong enough to act against the counterweight 67 and the dead weight of the rod 57 and change the gates over with a crisp action. The mass of the counterweight 67 and strength of the spring 68 are to be determined by trial and error. In figures 34a, 34b, 34c, 35a, 35b, 35c and 36 there is shown an alternative arrangement for change over using two springs 69, 70 acting on the rod 57. Energy is stored in the respective springs 69, 70 during each stroke of the float 12 by a cam arrangement 71 with the energy released in a manner similar to that already described for the counterweight and spring arrangement. A follower arm 971 is fixedly attached to the control rod 57 and moves around a cam track 971 to control the movement of control rod 57 in the same way that the follower arm 65 controls motion as described above. A second follower arm 970 is provided which is slidably mounted on the control rod 70 and which moves in a track 973. The follower arm 970 acts to compress in turn an upper spring 69 which acts between the follower arm 970 and a shoulder 974 on the control rod 57 and a lower spring 70 which acts between the follower arm 970 and a shoulder 975 on the control rod 57. The energy stored by the compressed upper spring 69 (see Figure 34b and Figure 36) can cause rapid upward movement of the control rod 57 to cause a gate valve changeover and energy stored by the compressed lower spring 70 (see Figure 35b) can cause a rapid downward movement of the control rod 57 to cause a gate valve changeover. A latch 960 is provided to be engageable with a notch 961 at the top of the control rod 57 to stop the operation of the engine.

Sectors 71A and 7IB of the cam arrangement 71 are adjusted and fixed in order to place the two points "A' and "C in the optimum positions for the gate change over to take place, the adjustments to be made by trial and error. Returning to the mechanism of Figures 16 to 24, the figure 16 shows a latch 73 mounted at the top of a gate change over mechanism frame 74. The engine is immobilised when the latch 73 is engaged in a notch 75 at the top of the rod 57 and no water, other than leakage, flows through the engine in this condition because the downstream gate valve 10 is always closed.

The ballasted mass of the float 12 is approximately 100 kg at the beginning of the down stroke after the water level in the float chamber 13 falls to the lower water level, which produces a resultant downward force of 1000N acting on the quadrant gear 14 causing the quadrant gear 14 to move through an angle of 60 degrees while exerting a steady force " f on output connecting rod 53, initially at a lever arm ~a 0' (the variation in the lever arm of quadrant gear 14 is illustrated graphically in figure 32 and 33 in which the circle 880 is the effective radius of the crank arm, B0 to B6 give connecting rod positions and 90 to 96 give the lever arms for the different connecting rod positions and Figure 32 shows a push-push action and the Figure 33 showing a pull/pull action - see later) . At the end of the 0.5m down stroke the system is back in equilibrium when the float is buoyant at the lower water level with nil force acting on the quadrant gear 14. After the change over of the gate valves 10, 11, the water level in the float chamber 13 rises almost instantaneously to the upper water level and the upwards force on the quadrant gear 14 is again 1000N acting on the quadrant gear 14 causing it to move back through 60 degrees. Again, the driving force acting on the quadrant reduces to zero at the end of the up stroke of the float when the system is in equilibrium and the float is buoyant at the top water level. Again, the steady force ~f initially at a lever arm "a 0' acts on connecting rod 52 during the up stroke.

The force ~f is dependent on the selected effective radius of the crank arms 15, 16. The greater the radius, the lower the force acting on joints and other components and a greater radius results in an increased stroke length acting on an output gear or on hydraulic rams (see later) . However, the radius is limited by the space available within the power take off housing 24 and in this context, the dimensions of the four major parts of the engine and thus the overall dimensions of the engine are to be kept to a minimum in order to facilitate easy carriage. A generator 76 is shown in Figure 27 to the left of the quadrant gear 14 for clarity but there could be scope for a more compact layout to achieve the aim of reduced overall dimensions.

A pull/pull action, where the crank arms 15, 16 turn away from driven wheels 77, 78 is provided in the working of the direct drive of figures 1 and 27 where motion is transmitted from the float 12 via the rack 20, the quadrant gear 14, the crank arms 15 and 16, sprung connecting rods 52 and 53 and a ratchet or clutch arrangement 79 to a pulley wheel 80 and then to the generator 76.

As illustrated by figure 32 and 33 the output force "f is steady during the stroke of the float 12 but the rate of linear change of the stroke at the output end of the connecting rods 52, 53 decrease during the stroke of the float 12. To partially overcome this condition the connecting rods 52 and 53 are spring loaded with the rating of the spring set so as to allow the float 12 to move faster at the beginning of each stroke when the spring becomes partly energised and for additional force to be available at the end of the stroke when the stored energy is released and continues the drive the output gearing even when the movement of the connecting rod has ceased. The rating of the springs is to be determined by trial and error.

The positions of the crank arm 15 and 16 relative to the axle of quadrant gear 14 are adjustable so as to be able to accommodate pull/pull and push/push action in horizontal working and in vertical working, all as shown in figure 24. With the float 12 at the upper end of the stroke, in theory the crank arm 15 should be horizontal but in practice the crank arm 15 should be set at up to say 5 degrees above the horizontal. In this way, the effective lever arm of the crank arm 15 reaches zero before the force exerted by the float 12 becomes zero at the end of the stroke causing the velocity of the float 12 to increase slightly before becoming buoyant again with a resultant shortening of the cycle time. The disadvantage is that the stroke of the output force on the ratchet or clutch driven wheel is reduced thus reducing the work done during the stroke but the power tends to increase with the faster working of the engine. Likewise, the crank arm 16 should be set at up to 5 degrees below the horizontal when the float is at the lower end of the stroke. Adjustment is brought about by the provision of bolts 81 which locate in slots 82 (or 83 if a push/push arrangement is used) in back plates 84 or 85 which are secured to the axle 301 of quadrant gear 14 (the crank arms 15 and 16 are secured to the axle 301 only via the back plates 84 and 85) .

In order to achieve the possibility of operating and testing the engine with different settings of the crank arms 15, 16 in either of the two modes of pull/pull or push/push, it is recommended that the crank arms 15, 16 should be mounted outside the supports for the quadrant axle bearings 86, 87, see figure 22. If placed "inside' the supports, the rods 52, 53 connecting the crank arms 15, 16 to the output power mechanism would need to be "hooked¹ to avoid contact with the axle at the end of each power stroke when operated in the pull/pull mode.

As an alternative to the direct drive to the generator 76, figures 28 to 31 show two versions of a hydraulic power take off with the head gear connected to pairs of ram pumps 88, 89 or 90, 91 supplying high pressure water to a Pelton wheel 92.

The output rams 88,89 are shown in figures 28, 29a and 29b with fixed cylinders and the output rams 90, 91 are shown in figures 30, 31a and 31b with trunnion mounted cylinders. The trunnion mounted cylinders have a better output performance because, as shown, the force in a connecting rod 93 of the fixed cylinder arrangement acts at an angle to the line of action of the ram 89 at the beginning of the output stroke with a resultant reduction in the effective force on the piston head.

Suitable filters are required in the supply of water to the rams 88, 89 or 90, 91 from an output surge chamber 94 (see figure 1) . Flexible hoses are required where the trunnion mounted rams 90, 91 are used.

A fixed weir 95 is shown in the downstream output surge chamber 94 (figure 1) with sliding shutter 96. when the shutter 96 is closed, water passes over the fixed crest so preserving a water level in the surge chamber 94 as a source of water for the pumps 88,89 or 90, 91 and also to prevent the float 12 from continuously striking a lower "stop' 97 at the end of the down stroke when the downstream water level is well below normal. The crest of the fixed weir should be set at 600mm below the level of the quadrant axle. The weir 95 could be made adjustable to adjust the lower level of water in the chamber 13.

The rams 87,88 or 90, 91 in Figures 28, 29a and 29b draw water from the water in the surge chamber 94 and pressurise the water to a design output pressure of 100 psi. The Pelton wheel 92 is driven by the output water and is connected to the generator 98 mounted in a watertight box. A needle valve 99 controlling the flow of water to the Pelton wheel 92 could be adjusted or stopped by a hand control connected to the needle valve or by a cable. The engine is self-starting and selfstopping with the system pressure maintained while the engine is stopped. A flywheel 100 is shown mounted on the gear train to smooth the output power.

In order to keep the system as simple as possible, a hydraulic accumulator is not included in the high pressure output line. Consequently, the electrical output will dip at the changeover of the gate valves which is acceptable provided the output power is used for battery charging or similar use. (The inclusion of an accumulator in the high pressure line would provide good quality power in terms of frequency control for a stand alone electricity generating plant) .

A push/push action would have the advantage that a non return valve on the delivery line can be mounted on the lower side of a ram but the disadvantage is that the changing geometry gives a slightly reduced efficiency because of the variation in change in the lever arm during the stroke of the float. A pull/pull arrangement has an almost perfect change in the lever arm during the stroke of the float but this arrangement requires a non return valve t be mounted in the head of a ram and thus a water tight joint on the shaft of the piston of the ram because there is high pressure water above the ram.

The efficiency of the engine with the various systems shown in Figures 28 to 31 will be less than the best performance achieved for other versions of the engine but the maximum continuous output power will exceed lOOw hydraulic power or more than 50w electrical power at 0.03 cumecs water supply. The power output would be increased with a square or rectangular base for the float.

A branch tapping is to be included in the high pressure line for a hose connection to supply linear or rotary power for equipment or machinery separately located.

In Figures 37, 38, 39 and 40 a further embodiment of power output drive train can be seen. In the figures the sprung connecting rods 52 and 53 are connected to a crankshaft 101, which is mounted in bearings 102 and 103 and which drives an output pulley wheel 104 (which will typically be connected by a belt to a generator) . A cam 106 is also mounted on the crankshaft 101 and the cam 106 controls a gate valve control mechanism such as that described in figures 16, 17, 18. 19, 20, 21, 22, 23a) and 23b); the cam 106 taking the place of the control island 60 appearing in the figures and the cam being engaged by a modified version of the follower member 65.

In the embodiment of Figures 37 to 40 the need for a clutch or ratchet mechanism is dispensed with since the drive mechanism is configured to allow continuous rotation in one sense of the crankshaft 101. This is done by adjusting the relative position of the crank arms 15 and 16 to the quadrant gear 14 carefully using bolts 81 and backplates 84 and 85 (as described earlier with reference to figures 24a) and 24b) ) . The positioning of the crank arms is adjusted so that figure 37 shows A as the position in which the U/S gate valve is closed and the D/S gate valve is opened, i.e. the quadrant gear 14 is at or near its uppermost point and a downstroke of the float 12 is about to commence. During the downstroke of the float 12 the quadrant gear 14 moves in the direction of the arrow shown in figure 37 and the crank arm transmits a push motion to the crank shaft 101 via the connecting rod 52. The spring in the connecting rod 52 enables energy to be stored at the beginning of the downstroke for subsequent release (and the length of the connecting rod 52 must in any case be variable to cope with varying geometry) . As can be seen from figure 37 the connecting rod 53 is at or near horizontal and acts through or nearly through the axis of the crankshaft 101 and thus the rod cannot apply a great torque to the crankshaft 101 and does not interfere unduly with the pushing action of the rod 52.

In figure 38 the drivetrain is shown in its configuration for an upstroke of the float 12. The figure 38 shows the position where the D/S gate valve 10 is just shut and the U/S gate valve 11 is just opened and the float 12 commences its upstroke. The connecting rod 53 at the end of the downstroke described above has been brought into the position shown in figure 38 and can now apply a pull on the crankshaft 101 as the quadrant gear 14 moves in the direction of the arrow shown in figure 38. Initially the connecting rod 52 does not apply any torque (or applies only a little) on the crankshaft 101 because there is no lever arm between the axis of the crankshaft 101 and the connecting rod 53. The spring in the connecting rod 53 stores energy at the commencement of the stroke for later use and permits the length of the connecting rod 53 to vary.

Eventually at the end of the upstroke illustrated in figure 38 the mechanism reaches the position of figure 37 and the process starts again.

A flywheel 105 is used to ensure that the crankshaft 101 keeps rotating in portions of the upstroke and downstroke of the float 12 in which little torque is applied to the crankshaft 101.

The use of the arrangement of Figures 37 to 40 does away with the need for a ratchet or a clutch mechanism, both of which are prone to wear, and makes the water engine more robust.

The water engine of the present invention can be used in the following manner: the base unit 22, the float chamber housing 23, the power take off unit 24, the intake surge chamber, the supply pipe 34 and the discharge pipe can be carried separately (for instance by hand) to the side of a small stream, as illustrated in figure 4 ; a hole is dug in the bank of the stream; the water engine is assembled by fixing the float chamber housing 23 to the base unit 24 using the lug fixings 26, by strapping the power take off unit 22 to the float chamber housing 23 and by push fitting the intake surge chamber 25 onto the base unit 22; the water engine is placed in the hole; a supply trench is dug to connect the water engine to the stream and the supply pipe 34 is laid in the trench and connected to the intake surge chamber 24 by push fixing in an aperture provided (after removal of a blank cover) ; a discharge trench is dug to connect the water engine to a point in the stream downstream of the inlet to the supply pipe 34 and the discharge pipe 35 is laid in the discharge trench and connected to the base unit 22 by push fitting in an aperture provided (after removal of a blank cover) ; a barrier is constructed in the stream between the supply pipe 34 and the discharge pipe 35 out of materials available on site (e.g. large stones, mud from a bank etc) in order to create a 0.5m operating head for the water engine; the generator of the water engine is connected to a battery to keep the battery charged.

The above method can include the steps of adjusting the gate valve control mechanism and the power output drivetrain in order to assure good operation of the engine (as described above) .

From the above method it must be appreciated that the water engine can be used to provide electrical power where no other power source is available.

Instead of being built into a bank beside a stream, the water engine could be installed next to a weir or a lock in order to keep charged a battery for operating water level control apparatus of the weir or the lock or as a power source to open and close lock gates or adjust the setting of sluice gates or other similar installations, where small amounts of power are required which can be extracted from a flow of water in a stream at a low operating head. In the control of sluice gates the engine would supply pressurised fluid to a piston and cylinder arrangement. The piston and cylinder arrangement would push and pull the rack of a rack and pinion arrangement. The pinion of the rack and pinion arrangement would be connected to a gear train for moving the sluice valve. This arrangement could ensure that the sluice gate cannot over a period of time move under its own weight and that motion would be possible only with operation of the piston and cylinder arrangement.

A further embodiment of engine is shown with references to Figures 42 to 53. In Figure 42 there can be seen a float 500 which is reciprocal in a chamber 501. The float 500 is connected to a lever arm 502 which is mounted on a shaft 503. A second lever arm 504 is also mounted on the shaft 503 and the lever arms 502 and 504 are connected to move together. The lever arm 504 is connected by a connecting rod 505 to a crankshaft 506. The crankshaft is then connected to the power output for the engine. The lever arm 502 forms with a pivotal link 507 a parallelogram movement arrangement for the float 500.

The arrangement is a simple arrangement by which the reciprocation of the float 500 is converted into a rotation of the crankshaft 506.

The engine shown in Figure 42 is in fact manufactured in two parts as can be seen in Figure 43, the top part having a housing 510 and the bottom part having a housing 511. The plan views of the engine at the levels 1, 2, 3, 4 indicated in Figure 43 are respectively shown in Figures 44, 45, 46 and 47. A plan view is given in Figure 48, a partial side elevation of the top part 510 in Figure 49a and a side elevation of the bottom part 511 in Figure 49b.

It can be seen in Figure 42 that a cam surface 599 is provided on the crankshaft 506 and this cam surface is used to control the timing of the opening and closing of gate valves in the engine.

A modification of the engine of Figures 42 to 47 is shown in Figures 50 to 55. This engine is modified by having a single housing, in which various components are slidably located. This can be seen clearly in Figure 51 where a first component 600, comprising a float 601, a chamber 602 and a power take-off mechanism 603 (this mechanism being as described in Figure 42) are provided in one integer 600, which can be slidably located in the slots 604, 605 which are defined on the sides of the housing. Furthermore, the gate valves are provided in gate frames 606 and 607, which are themselves slidably located in slots 608 and 609 (see Figure 53 and figure 54) . In Figure 52 the integer 600 can be seen in detail.

In Figure 55 it can be seen that the engine is preferably located in concrete 610 and rag bolts, e.g. 611, are fitted through the housing wall to secure the engine in the concrete surround.

In Figure 50 a part of the control mechanism of the invention can be shown and it can be seen that a follower arm 620 follows the cam 699 provided on the crankshaft. The follower arm 620 is linked by a link 621 to a pivot arm 622 which is pivotally mounted in the housing and which has a weight 623 at one end.

The arm 622 is then connected to the actual mechanism for changing the gate valves, which is not shown in the Figure but which is similar to the mechanisms previously shown. A roller 624 on the follower arm 620 follows the cam surface 607 up until the abrupt end of the cam surface, when the follower arm then drops down due to gravity. This dropping motion causes the arm 622 to pivot the weight 623 upwardly and thereby cause a change in the valve mechanism. The weight 623 is kept in its upward position by a detente on a surface 630 shown in the Figure. An abutment member 631 is provided on the shaft 640 which is connected to the lever arm 641 which is in turn pivotally connected to the float 642. When the abutment member 631 hits the panel 650 attached to the surface 630, the weight 623 is released to drop downwardly and cause a change over in the valve mechanism.

A very simple gate valve switch-over mechanism is shown in Figure 56 schematically where a float 700 is reciprocal in a chamber (not shown) . On top of the float 700 there is a spring 701 mounted on a suitable rod 702. Similarly extending from the bottom of the float 700 there is a spring 703 mounted on a suitable rod 702. The springs 701 and 703 can engage arms 704,705 mounted on a vertically extending rod 706 which is connected to the gate valve change-over mechanism (not shown for reasons of simplicity) . When the float 700 moves upwards in the chamber then the spring 701 is compressed until such time as the spring 701 has stored enough energy to overcome resistance to motion of the rod 706. When the resistance to motion has been overcome then the spring 701 relaxes and pushes the rod upwardly. In a similar fashion, the spring 703 is compressed when the float 700 moves downwardly and when sufficient energy is stored in the spring 703 then the spring is able to overcome the resistance to motion of the rod 706, which then moves under the action of the spring.

Figure 57 shows a modification of the Figure 1 engine in which the majority of the components are the same and thus will not be described. In this embodiment the float 12 is connected directly a reciprocal armature of a linear electricity generator 1000 to produce electricity. A quadrant gear 14 is still used to engage the float 12 but this is used solely to control opening and closing of the gates 10 and 11 (as described previously) rather than to provide power take off. Since the linear generator 1000 only requires linear rather than rotational motion a simple direct connector is possible.

The engines described above are ideally suited for use in the control of sluice gates used in the control of water flow (e.g. at locks, in canals or in rivers) . Such sluice gates are typically quite isolated and it is difficult to run an electricity supply from the mains to them. The sluice gates are not moved often and not rapidly. They are always used where there is a head of water. Thus the present invention is ideally suited to use in generating electricity to power an electric motor which moves a sluice gate. Probably an accumulator would be used which is continuously charged by the engine of the invention and which supplies power to the electric motor. Alternatively, the engine of the invention could be simply used to supply pressurised fluid for use in driving a rack of a rack and pinion arrangement connected to a sluice gate. The use of a rack and pinion arrangement for the sluice gate is preferred since it can be constructed such that the sluice gate can only move when powered to do so and not under gravity.

Claims

CLAIMS 1. An engine comprising: a chamber, a float reciprocable in the chamber, supply means for supplying a liquid to the chamber from a head of liquid, outlet means for receiving liquid from the chamber, inlet valve means for controlling flow of liquid into the chamber, outlet valve means for controlling flow of liquid out of the chamber, and power output means connected to the float to convert motion of the float to a power output for the engine, wherein in use of the engine the inlet and outlet valve means respectively and successively admit liquid into the chamber from the supply means and allow flow of liquid from the chamber to the outlet means in order to cause the float to reciprocate in the chamber, and a control mechanism is provided to control the opening and closing of the inlet and outlet valve means, in timed relationship to movement of the float in the chamber, characterised in that the control mechanism comprises: first biasing means for biasing the control mechanism into a first operating condition in which the outlet valve means is closed and the inlet valve means is open, second biasing means for biasing the control mechanism into a second operating condition in which the inlet valve means is closed and the outlet valve means is open, a timing mechanism which controls when the first and second biasing means bias the control mechanism into the first and second operating conditions, the timing mechanism being linked to the float in order to control the action of the first and second biasing means in timed relationship to the motion of the float, and means for converting motion of the float to stored potential energy in the first and second biasing means.

2. An engine as claimed in claim 1 wherein the means for converting motion of the float to stored potential energy converts the motion of the float to stored potential energy cyclically in one of the first and second biasing means and then the other biasing means.

3. An engine as claimed in claims 1 or claim 2, wherein the timing mechanism and the means for converting motion of the float to stored potential energy are provided by an arrangement comprising a follower member abuttable with a profiled control surface movable relative to the follower member, the follower member being connected to the inlet and outlet valve means and the control surface being provided on a member which is mechanically linked to and which moves in timed relationship with the float.

4. An engine as claimed in claim 3 wherein during the operation of the engine the motion of the follower member and the profiled control surface relative to each other has at least the following four phases: a first phase during which abutment of the follower member with the profiled control surface prevents the first biasing means from biasing the inlet and outlet valve means to the first operating condition and during which potential energy is stored in the first biasing means, a second phase during which the follower member is permitted to move under the action of the first biasing means, the first biasing means releasing the potential energy stored in the first phase to bring the inlet and outlet valve means to the first operating condition; a third phase during which abutment of the follower member with the profiled control surface prevents the second biasing means from biasing the inlet and outlet valve means to the second operating condition and during which potential energy is stored n the second biasing means; and a fourth phase during which the follower member is permitted to move under the action of the second biasing means, the second biasing means releasing the potential energy stored in the third phase to bring the inlet and outlet valve means to the second operating condition.

5. An engine as claimed in claim 3 or claim 4 wherein the profiled control surface is provided on a cam which is mechanically linked to the float and which rotates continuously in one direction during reciprocation of the float in the chamber.

6. An engine as claimed in claim 4 wherein the profiled control surface is provided by a land which is provided on a lever arm which is in turn pivotally mounted on a shaft mechanically linked to the float, the reciprocal motion of the float in the chamber causing the lever arm to rotate back and forth in an oscillatory fashion.

7. An engine as claimed in claim 6 wherein the follower member directly engages the land and the land has at least two distant profiled control surfaces: a first surface which faces inwardly towards the shaft and which is abutted by the follower member during the said first phase of relative motion, the follower member travelling along the first surface by virtue of the rotation of the lever arm in a first sense; and a second surface which faces outwardly away from the shaft and which is abutted by the follower member during the said third phase of relative motion, the follower member travelling along the second surface by virtue of rotation of the lever arm in a second sense opposite to the said first sense, the second surface being radially spaced apart from the first surface at a greater distance from the shaft; and wherein in use of the engine: the follower member on reaching the end of the first surface is forced away from the shaft by the first biasing means to a radial distance from which the follower member can be brought into abutment with the second surface by the second biasing means, the follower member on reaching the end of the second surface is forced towards the shaft by the second biasing means to a radial distance from which the follower member can be brought into abutment with the first surface by the first biasing means.

8. An engine as claimed in claim 6 or claim 7 wherein the land is provided by a member which stands proud of the lever arm.

9. An engine as claimed in claim 6 or claim 7 wherein the land is defined by a grooved channel in the lever arm .

10. An engine as claimed in claim 7 wherein the land is formed of first and second parts movable relative to each other to permit the length of the first and second surfaces to be adjusted and locking means is provided to secure the first and second parts relative to each other once adjustment has been effected.

11. An engine as claimed in any one of the preceding claims wherein one of the first and second biasing means comprises a mass and potential energy is stored in the first biasing means by raising the mass from a lower to a higher position.

12. An engine as claimed in any one of the preceding claims wherein the second biasing means comprises a spring and potential energy is stored in the spring by compressing the spring.

13. An engine as claimed in any one of claims 1 to 10 wherein one of the first and second biasing means comprises a spring and potential energy is stored in the spring by compressing the spring.

14. An engine as claimed in claim 4 wherein the first biasing means is a mass connected to the follower member, and the profiled control surface is profiled in such a way that during the said first phase of relative motion the mass is held in a raised position by abutment of the follower member with the profiled control surface and during the said second phase of relative motion the weight of the mass causes the follower member to fall downwardly under the action of gravity .

15. An engine as claimed in claim 14 wherein latch means is provided which can secure the mass in the uppermost position thereof and thereby stop operation of the engine.

16. An engine as claimed in any one of claims 4, 14 or 15, wherein the second biasing means comprises spring means connected between the follower member and a lever arm mechanically linked to the float which rotates back and forth about a pivot axis in an oscillatory manner as the float reciprocates in the chamber, the profiled control surface being profiled in such a way that the spring means is extended during the said third phase of relative motion.

17. An engine as claimed in claim 1 or claim 2 wherein the turning mechanism and the means for converting motion of the float to stored potential energy as provided by an arrangement comprising a first follower member abuttable with a first profiled control surface movable relative the first follower member and a second follower member abuttable with a second profiled control surface movable relative to the second follower member, the first and second follower members being connected to the inlet and outlet valve means and the first and second control surfaces being provided on one or more members mechanically linked to the float which move in timed relationship with the float.

18. An engine as claimed in claim 17 wherein the first biasing means comprises a first spring connected between the first follower member and a fixed point and a second spring connected between the second follower member and a fixed part, the first and second profiled surfaces being arranged such that when the float moves downward in the chamber one of the first and second springs is compressed and when the float moves upward in the chamber the other of the first and second springs is compressed.

19. An engine comprising: a chamber, a float reciprocable in the chamber, supply means for supplying a liquid to the chamber from a head of liquid, outlet means for receiving liquid from the chamber, inlet valve means for controlling flow of liquid into the chamber, outlet valve means for controlling flow of liquid out of the chamber, power output means connected to the float to convert motion of the float to a power output for the engine, wherein in use of the engine the inlet and outlet valve means respectively and successively admit liquid into the chamber from the supply means and allow flow of liquid from the chamber to the outlet means in order to cause the float to reciprocate in the chamber, and control means is provided to control the opening and closing of the inlet and outlet valve means in timed relationship to movement of the float in the chamber, and the power output means comprises a mechanical linkage connecting the float to the power output means characterised in that the power output means which comprises a rotatable shaft and the mechanical linkage means converts the reciprocal motion of the float into a rotation of the shaft and operates to rotate the shaft in one rotational sense only.

20. An engine as claimed in claim 19 wherein the mechanical linkage does not use hydraulic fluid to transmit motion from the float to the power output means.

21. An engine as claimed in claim 19 or claim 20 wherein the mechanical linkage comprises: a rack attached to the float which reciprocates linearly with reciprocal motion of the float, first gear means engaging the first rack, and a first shaft connected to the first gear means, a first lever arm which extends radially from the first shaft in a first radial direction, a second lever arm which extends radially from the first shaft in a second radial direction different to the first radial direction, a crankshaft connected to the output shaft, a first connecting rod connecting the first lever arm to a first crank arm of the crankshaft, and a second connecting rod connecting the second lever arm to a second crank arm of the crankshaft, wherein as the float reciprocates in the chamber the reciprocal motion is relayed via the rack and the first gear means to the first shaft which is thereby driven to oscillate back and forth and the first and second connecting rods then relay the oscillatory - 38 -

motion to the crankshaft, which rotates in one direction.

22. An engine as claimed in claim 21 wherein the mechanical linkage comprises a clutch mechanism which acts between the first and second crank arms and the crankshaft and ensures that only rotation of only one sense is transmitted to the crankshaft.

23. An engine as claimed in claim 21 wherein the mechanical linkage comprises a ratchet mechanism which acts between the first and second crank arms and the crankshaft and ensures that only rotation of one sense is transmitted to the crankshaft.

24. An engine as claimed in any one of claims 21 to 23 wherein both of the first and second connecting rods are variable-length connecting rods which include spring means which can be compressed to store potential energy and which can relax to release stored energy to the crankshaft.

25. An engine as claimed in claim 19 or claim 20 wherein the mechanical linkage means comprises: a first lever arm pivotally connected to the float and mounted to extend from a first shaft in a first radial direction, a second lever arm extending from the first shaft in a second radial direction different to the first radial direction, a crankshaft connected to the output shaft, a connecting rod connecting the second lever arm to a crank arm of the crankshaft, wherein reciprocation of the float in the chamber causes the first lever arm to rock back and forth in an oscillatory fashion which in turn causes the first shaft and then thereby the second lever arm to rock back and forth in an oscillatory fashion, and the oscillating motion of the second lever arm is relayed by the connecting rod to the crankshaft which is rotated in one direction.

26. An engine as claimed in claim 25 wherein the first lever arm is connected to a top portion of the float and a third lever arm is connected between a bottom portion of the float and a fixed reference, the first and third lever arms forming a parallelogram pivot arrangement for the float.

27. An engine as claimed in any one of claims 19 to 25 wherein the power output means comprises an electrical generator with a rotor drive to rotate by the engine and electrical connector means which enable connection of the electrical generator to a load.

28. An engine a claimed in any one of claims 19 to 27 comprising additionally a flywheel in the power output means.

29. An engine as claimed in any one of the claims 19 to 28 wherein all components of the engine are located in a housing and the power output means and the linkage means are located in a compartment alongside the chamber.

30. An engine as claimed in any one of claim 21 to 24 wherein the rack is attached to the side of the float.

31. An engine comprising: a chamber, a float reciprocable in the chamber, supply means for supplying a liquid to the chamber from a head of liquid, outlet means for receiving liquid from the chamber, inlet valve means for controlling flow of liquid into the chamber, outlet valve means for controlling flow of liquid out of the chamber, power output means connected to the float to convert motion of the float to a power output for the engine, wherein in use of the engine the inlet and outlet valve means respectively and successively admit liquid into the chamber from the supply means and allow flow of liquid from the chamber to the outlet means in order to cause the float to reciprocate in the chamber, and control means is provided to control the opening and closing of the inlet and outlet valve means in a timed relationship to movement of the float in the chamber, characterised in that the power output means comprises: a hydraulic piston and cylinder arrangement which is driven by the engine to compress liquid, a nozzle through which the compressed liquid is forced as a jet and a Pelton wheel driven to rotate by the jet of compressed liquid.

32. An engine as claimed in claim 31 wherein the Pelton wheel drives an output shaft.

33. An engine as claimed in claim 32 wherein the output shaft is connected to a rotor of an electrical generator and the engine comprises electrical connection means which enables the electrical generator to be connected to a load.

34. An engine as claimed in claim 32 or claim 33, wherein the Pelton wheel is connected to a flywheel.

35. An engine as claimed in any one of claims 31 to 33 wherein the nozzle is adjustable and flow rate of the jet of liquid can thereby be adjusted.

36. An engine comprising: a chamber, a float reciprocable in the chamber, supply means for supplying a liquid to the chamber from a head of liquid, outlet means for receiving liquid from the chamber, inlet valve means for controlling flow of liquid into the chamber, outlet valve means for controlling flow of liquid out of the chamber, power output means connected to the float to convert motion of the float to a power output for the engine, wherein in use of the engine the inlet and outlet valve means respectively and successively admit liquid into the chamber from the supply means and allow flow of liquid from the chamber to the outlet means in order to cause the float to reciprocate in the chamber, and control means is provided to control the opening and closing of the inlet and outlet valve means in timed relationship to movement of the float in the chamber, characterised in that the power output means comprises: a rack which reciprocates linearly with reciprocation of the float in the chamber, first gear means which engages the rack, a first float connected to the first gear means, a first lever arm connected to the first shaft and extending from the first shaft in a first radial direction, a first hydraulic piston and cylinder arrangement pivotally connected to a fixed point in the engine, and a first connecting rod connecting the first lever arm to the piston of the first hydraulic piston and cylinder arrangement, whereby when the float reciprocates in the chamber, the reciprocal motion is conveyed via the first gear means to the first shaft which is rotated back and forth in an oscillatory manner, thereby causing the first lever arm to rotate back and forth, and the motion of the first lever arm is transmitted by the first connecting rod to cause relative motion between the piston and cylinder of the first piston and cylinder arrangement which is driven to draw liquid into the piston and cylinder arrangement and compress the liquid for subsequent output, the piston and cylinder arrangement pivoting during operation to align the axis of the cylinder of the arrangement with the axis of the fist connecting rod.

37. An engine as claimed in claim 36 comprising additionally a second lever arm connected to the first shaft which extends from the first shaft in a second radial direction different to the first radial direction and a second piston and cylinder arrangement connected by a second connecting rod to the second lever arm, the second piston and cylinder arrangement being pivotally connected to a fixed point of the engine, whereby when the float reciprocates in the chamber the oscillating rotation of the first shaft causes the second lever arm to rotate back and forth and the motion of the second lever arm is transmitted to the second hydraulic piston and cylinder arrangement to cause relative motion between the piston and the cylinder of the second hydraulic piston and cylinder arrangement, which is driven to draw liquid into the piston and cylinder arrangement and compress the liquid for subsequent output, the second piston and cylinder arrangement pivoting during operation to align the axis of the cylinder thereof with the second connecting rod, the fist and second lever arm being arranged such that when the first piston and cylinder arrangement is drawing in liquid, the second piston and cylinder arrangement is compressing liquid and vice versa .

38. A method of manufacture and installation of an engine which comprises: a chamber, a float reciprocable in the chamber, supply means for supplying a liquid to the chamber from a head of liquid, outlet means for receiving liquid from the chamber, inlet valve means for controlling flow of liquid into the chamber, outlet valve means for controlling flow of liquid out of the chamber, power output means connected to the float to convert motion of the float to a power output for the engine, wherein in use of the engine the inlet and outlet valve means respectively and successively admit liquid into the chamber from the supply means and allow flow of liquid from the chamber to the outlet means in order to cause the float to reciprocate in the chamber, control means is provided to control the opening and closing of the inlet and outlet valve means in timed relationship to movement of the float in the chamber, the method including the step of part assembling the engine to form a plurality of separate integers each comprising a housing, transporting the plurality of separate integers to a site where the engine is to be used and then assembling the integers together to form the complete engine.

39. A method as claimed in claim 38 wherein the engine is part assembled into: a first integer having a housing in which are provided a top part of the chamber, the power output means and a part of the control means, and a second integer having a housing in which are provided the remainder of the chamber, the inlet valve means, the outlet valve means, and the remainder of the control means.

40. A method as claimed in claim 39 wherein the housing of the first integer is push fitted into the housing of the second integer to assemble the engine on site .

41. A method as claimed in claim 38 wherein the engine is part assembled into: a first integer which is a base unit and which has a housing in which there are provided the inlet valve means, the outlet valve means, part of the control means and a bottom portion of the chamber, a second integer which has a housing in which the remainder of the chamber is defined, and a third power take off integer which has a housing in which there are provided the power output means and the remainder of the control means, and in which the first, second and third integers are assembled by hand or by using hand tools using connection means provided on the housings of the first, second and third integers, the user during final assembly connecting the power output means to a float inserted in the chamber.

42. A method as claimed in claim 41 wherein the engine is part assembled into a fourth integer which has a housing in which an intake surge compartment is defined, the intake surge compartment being capable of containing a head of liquid for supply to the chamber.

43. A method as claimed in any one of claims 38 to 42 in which the part-assembled integers are carried to the site of installation by hand.

44. A method of use of an engine as claimed in any one of claims 1 to 37 comprising the steps of: digging a hole in the bank of a waterway, locating the engine in the hole, connecting the supply means to a first point of the waterway, connecting the outlet means to a second point of the waterway downstream from the first point, and placing an obstruction in the waterway to create a head of water between the first and second point.

45. A method a claimed in claim 44 wherein a first pipe is used to connect the engine to the first point in the waterway and a second pipe is used to connect the engine to the second point in the waterway.

46. A method of use of an engine as claimed in any one of claims 1 to 37 wherein the power output means is used to supply an electric current to charge a battery.

47. A method of manufacture and installation of an engine which comprises: a chamber, a float reciprocable in the chamber, supply means for supplying a liquid to the chamber from a head of liquid, outlet means for receiving liquid from the chamber, inlet valve means for controlling flow of liquid into the chamber, outlet valve means for controlling flow of liquid out of the chamber, power output means connected to the float to convert motion of the float to a power output for the engine, wherein in use of the engine the inlet and outlet valve means respectively and successively admit liquid into the chamber from the supply means and allow flow of liquid from the chamber to the outlet means in order to cause the float to reciprocate in the chamber, and control means is provided to control the opening and closing of the inlet and outlet valve means in timed relationship to movement of the float in the chamber, the method including the step of assembling the chamber, the inlet valve means, the outlet valve means, the supply means, the outlet means, the power output means and the control means in a housing and then transporting the housing to a site where the engine is to be used and connecting the supply means to a supply of liquid and the outlet means to an outlet for liquid.

48. A method as claimed in claim 47 wherein the engine is secured in use by securing the housing to a concrete surround using bolts.

49. An engine comprising a housing in which are provided: a chamber, a float reciprocable in the chamber, supply means for supplying a liquid to the chamber from a head of liquid, outlet means for receiving liquid from the chamber, inlet valve means for controlling flow of liquid into the chamber, outlet valve means for controlling flow of liquid out of the chamber, power output means connected to the float to convert motion of the float to a power output for the engine, wherein in use of the engine the inlet and outlet valve means respectively and successively admit liquid into the chamber from the supply means and allow flow of liquid from the chamber to the outlet means in order to cause the float to reciprocate in the chamber, and control means is provided to control the opening and closing of the inlet and outlet valve means in timed relationship to movement of the float in the chamber, characterised in that the engine also comprises a discharge surge compartment in the housing which receives liquid output from the chamber.

50. An engine as claimed in claim 47 wherein an adjustable weir is provided in the discharge surge compartment which allows control of liquid level in the chamber during a downstroke of the float.

51. An engine as claimed in claim 49 or 50 wherein an intake surge compartment is provided in the housing which can contain a head of liquid.

52. An engine comprising: a chamber, a float reciprocable in the chamber, supply means for supplying a liquid to the chamber from a head of liquid, outlet means for receiving liquid from the chamber, inlet valve means for controlling flow of liquid into the chamber, outlet valve means for controlling flow of liquid out of the chamber, power output means connected to the float to convert motion of the float to a power output for the engine, wherein in use of the engine the inlet and outlet valve means respectively and successively admit liquid into the chamber from the supply means and allow flow of liquid from the chamber to the outlet means in order to cause the float to reciprocate in the chamber, and control means is provided to control the opening and closing of the inlet and outlet valve means in timed relationship to movement of the float in the chamber, characterised in that the inlet valve means and the outlet valve means are secured in position by securing means which permit removal of the inlet valve means and/or the outlet valve means from the engine for maintenance purposes.

53. An engine as claimed in claim 52 wherein the inlet valve means and the outlet valve means each comprise a gate valve rotatable in a frame and the securing means comprises slots into which the frames of the gate valves can be slid to secure the gate valves in operating positions and out of which the frames can be subsequently withdrawn for maintenance of the gate valves.

54. An engine as claimed in claim 52 or 53 wherein the chamber is at least partly defined by a wall member which is removably located in the engine so that the wall member can be withdrawn from the engine by a user to permit access to the inlet and outlet valve means.

55. An engine as claimed in claim 54 wherein the wall member has runners which are slid into slots to secure the wall member in place in the engine and the runners can be withdrawn from the slots to permit withdrawal of the wall member from the engine.

56. An engine comprising: a chamber, a float reciprocable in the chamber, supply means for supplying a liquid to the chamber from a head of liquid, outlet means for receiving liquid from the chamber, inlet valve means for controlling flow of liquid into the chamber, outlet valve means for controlling flow of liquid out of the chamber, power output means connected to the float to convert motion of the float to a power output for the engine, wherein in use of the engine the inlet and outlet valve means respectively and successively admit liquid into the chamber from the supply means and allow flow of liquid from the chamber to the outlet means in order to cause the float to reciprocate in the chamber, and control means is provided to control the opening and closing of the inlet and outlet valve means in timed relationship to movement of the float in the chamber, characterised in that the power output means comprises a linear generator of electricity powered by the motion of the float, the reciprocal motion of the float being transmitted by a mechanical linkage to a moving part of the linear generator.

57. A method of using an engine which comprises: a chamber, a float reciprocable in the chamber, supply means for supplying a liquid to the chamber from a head of liquid, outlet means for receiving liquid from the chamber, inlet valve means for controlling flow of liquid into the chamber, outlet valve means for controlling flow of liquid out of the chamber, power output means connected to the float to convert motion of the float to a power output for the engine, wherein in use of the engine the inlet and outlet valve means respectively and successively admit liquid into the chamber from the supply means and allow flow of liquid from the chamber to the outlet means in order to cause the float to reciprocate in the chamber, and control means is provided to control the opening and closing of the inlet and outlet valve means in timed relationship to movement of the float in the chamber, the method comprising using the engine to drive a sluice gate with the engine being powered by the head of liquid between the sides of the sluice gate.

58. A method as claimed in claim 57 wherein the driven sluice gate is the sluice gate of a lock.

59. A method as claimed in either of claims 57 or 58 wherein the power output means of the engine supplies pressurised fluid to a piston and cylinder arrangement, the piston and cylinder arrangement being used to drive a rack of a rack and pinion arrangement which is in turn connected by gear means to the sluice gate, whereby the sluice gate can only move when powered by the piston and cylinder arrangement and cannot move under gravity.

60. An engine comprising: a chamber, a float reciprocable in the chamber, supply means for supplying a liquid to the chamber from a head of liquid, outlet means for receiving liquid from the chamber, inlet valve means for controlling flow of liquid into the chamber, outlet valve means for controlling flow of liquid out of the chamber, power output means connected to the float to convert motion of the float to a power output for the engine, wherein in use of the engine the inlet and outlet valve means respectively and successively admit liquid into the chamber from the supply means and allow flow of liquid from the chamber to the outlet means in order to cause the float to reciprocate in the chamber, and control means is provided to control the opening and closing of the inlet and outlet valve means in timed relationship to movement of the float in the chamber, wherein each of the inlet valve means and outlet valve means comprises a valve member pivotable in an aperture and sealing means secured around the periphery of the aperture, the sealing means comprising an elastically resilient material, the sealing means being seals characterised in having a hollow cross-section whereby the compliance of the seals is enhanced.

61. An engine as claimed in claim 60 wherein the sealing means are made of rubber.

62. An engine substantially as hereinbefore described with reference to and as shown in the accompanying drawings.