Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
  • F03B—MACHINES OR ENGINES FOR LIQUIDS
  • F03B13/00—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates
  • F03B13/12—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy
  • F03B13/14—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using wave energy
  • F03B13/16—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using wave energy using the relative movement between a wave-operated member, i.e. a "wom" and another member, i.e. a reaction member or "rem"
  • F03B13/18—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using wave energy using the relative movement between a wave-operated member, i.e. a "wom" and another member, i.e. a reaction member or "rem" where the other member, i.e. rem is fixed, at least at one point, with respect to the sea bed or shore
  • F03B13/1845—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using wave energy using the relative movement between a wave-operated member, i.e. a "wom" and another member, i.e. a reaction member or "rem" where the other member, i.e. rem is fixed, at least at one point, with respect to the sea bed or shore and the wom slides relative to the rem
  • F03B13/1865—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using wave energy using the relative movement between a wave-operated member, i.e. a "wom" and another member, i.e. a reaction member or "rem" where the other member, i.e. rem is fixed, at least at one point, with respect to the sea bed or shore and the wom slides relative to the rem where the connection between wom and conversion system takes tension only
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
  • F05B2240/00—Components
  • F05B2240/40—Use of a multiplicity of similar components
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
  • F05B2260/00—Function
  • F05B2260/40—Transmission of power
  • F05B2260/406—Transmission of power through hydraulic systems
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/30—Energy from the sea, e.g. using wave energy or salinity gradient

Definitions

• This patent application presents a design of a winch based wave energy absorbing buoy, where a self-tightening winch, mounted on or otherwise connected to the buoy, serves as anchoring system, and at the same time provide energy absorption.
• the system also comprises an overload protection strategy based on the simple principle of not letting more energy into the system than the system itself can handle.
• the self-tightening-mechanism of the winch is furthermore integrated in the energy-conversion and power-take-off system, which helps to lower the design costs of the wave power plant.
• the invention comprises the following elements and subsystems: a wave energy absorbing floating body or buoy, a winch, well known hydraulic components and standard means for converting hydraulic flow and pressure into electricity, among others. But the system assembly has certain characteristics, which the parts and subsystems do not have separately.
• the fundamental principle of overload protection provided with the invention is about limiting power through-put by simply "letting go” and not absorbing more energy from the waves when maximum power input limit has been reached, so that the amount of energy conducted into the system never will become excessive.
• This fundamental principle has never elsewhere been described as part of a winch- anchored buoy-based ocean wave power absorption- and power conversion system's survivability strategy in extreme waves.
• One of the overload protection means described in this document, to execute this principle in practice, involves a slip clutch 16 which is disengaged when the amount of energy per time unit transferred from the buoy 23 via the wire 14 and the winch 12 through the winch axle 18 has reached a certain upper limit.
• slip clutches in wave-power plants is mentioned in DE 2850293, WO 96/30646 and US 4228360. But these lack the necessary characteristics in order for a wave-power plant, without incurring unreasonably large design costs, to be capable of surviving the encounter with the at times extreme forces of the ocean waves in the event of storms and hurricanes.
• Figure 1 shows one example embodiment of a system for energy conversion, energy storage and power-take-off according to the invention.
• Figure 2 shows a cross section side view of one embodiment of the wave-power plant, where the winch 12 is placed inside the buoy 23.
• Figure 3 is a bottom view of the wave-power plant in the embodiment corresponding to figure 2.
• Figure 4 shows a winch 12 with a slightly conical cable drum.
• Figure 5 shows another example embodiment of the system for energy conversion, energy storage and power-take-off according to the invention.
• the device according to the invention comprises a wave energy absorbing floating buoy with energy absorption- and conversion system connected to a generator, which may be placed inside the buoy.
• Figures 1, 2, 3, 5 and 6 illustrate the principle of the device according to the invention.
• a floating buoy 23 (fig. 2) acts as absorption element. This buoy is connected to a winch 12 with a winch wire 14.
• the buoy 23 and the winch 12 with the winch ,wire 14 are connected in such a manner that the winch is forced to rotate when the wave forces move the buoy 23 in the winch wire's longitudinal direction.
• the winch and the winch wire interconnect the buoy and a reference body below the waves of the ocean surface.
• This reference body may be a pelagic anchor plate, an anchor 19 at the seabed as shown in figure 2, an expansion bolt in the rock of the seabed, or a different anchoring device.
• the winch is in the buoy. But the winch may also, instead of being integrated in the buoy, be placed elsewhere, for example at the seabed or in a pelagic anchoring device.
• the energy absorbed from the waves when the winch is forced to rotate, is transmitted in the form of rotating motion from the winch axle 18 to a mechanical energy conversion subsystem 20, powering a hydraulic subsystem 21.
• the absorbed energy is converted into hydraulic potential energy in the form of p • V (pressure multiplied by volume) inside an accumulator 8, where a compressible fluid serves as energy storage medium.
• the accumulator powers a hydraulic motor 10, which in turn runs an electric generator 28.
• the accumulator also powers the winch-tightening mechanism which is integrated with the mechanical energy conversion subsystem and the hydraulic subsystem, ie. that the mechanical energy conversion subsystem and the hydraulic subsystem comprises functionality which inherently provides winch tightening.
• the fundamental functionality of this integration is that spooling- in the winch wire a certain length requires lesser volume of fluid to flow out of the accumulator, than the volume of fluid which is pumped into the accumulator when the winch wire is pulled out an equal length.
• the hydraulic subsystem and possibly parts of the mechanical energy conversion system may be assembled in such a manner that the displacement of the pump(s) is higher on outward rotations of the winch than on inward rotations.
• the term 'displacement' refers to pump volume capacity per revolution of the pump shaft. This may be accomplished by means of a variable displacement pump and a governing system which alters the displacement of the pump according to the direction of the hydraulic flow at any given moment, or by a system assembly like the one exemplified in figure 1, where instead of one pump, two pumps are connected to the mechanical energy conversion system; smaller pump 11 with a relatively lower displacement and a larger pump 3 with a relatively higher displacement. Both pumps may draw fluid from the same atmospheric pressure fluid reservoir 1.
• both pumps pump fluid under high pressure into the hydraulic accumulator 8.
• the smaller pump 11 also acts in the opposite direction as a motor, powered by the accumulator, forcing the winch to wind in, when the forces that pull the wire out drop sufficiently.
• the larger pump 3 is disengaged due to check valve 7, preventing fluid from flowing from the accumulator 8 through pump 3 back into the fluid reservoir 1, and a one way clutch 29 mounted on the shaft connecting the mechanical machinery 20 to the pump 3.
• a mechanical gear transfer system may be applied, that alters the gear ratio to provide a higher rotational speed of the pump(s) compared to the rotational speed of the winch axle 18, on outward rotations of the winch, than on spooling in.
• a mechanical gear transfer system may for example be an assembly of gears and clutches, like the one exemplified in figure 5, where the clutches arrange for the transfer of rotational motion to be channelled through a gear path with a higher gear ratio on outward rotations than the gear path through which the rotational motion is channelled on inward rotations.
• the mechanical energy conversion subsystem The mechanical energy conversion subsystem
• the mechanical energy conversion system 20 converts mechanically the rotational energy from the winch 12, and transfers that rotational energy to the hydraulic subsystem 21.
• the main purpose of the mechanical energy conversion system is to ensure that the mechanical energy transferred to the hydraulic subsystem has the qualities necessary to make the hydraulic subsystem function optimally with the highest possible efficiency.
• An additional purpose of the mechanical energy conversion system is to provide for winch tightening in co-operation with the hydraulic subsystem, as explained further down.
• the mechanical energy conversion subsystem comprises the following parts: • a shock absorbing rubber link 13 in the extension of the winch axle 18
• the slip clutch 16 is further connected via an axle 25 to the first overrunning clutch 29, which is connected via an axle 27 to gear transmission systems 17 and 33, where the rotational motion is geared up and transferred — on outward rotations of the winch — to a gear-penetrating axle 26 which is also connected directly to axle 35 through the second overrunning clutch 34.
• Both gear transmission systems 17, 33 must be of the same type with regards to rotational direction of the output shaft in relation to the input shaft's rotational direction: Either none of them must cause direction reversal, or both have to cause direction reversal, in order to provide that the output axle 26 from gear transmission system 33 and the output axle 35 from gear transmission system 15 run in the same direction.
• the two overrunning clutches are coupled so they work in each other's reverse directions.
• the axle 26 may be described as a fast-rotating axle, whilst the axle 35 may be described as a slowly- rotating axle, due to the fact that axle 26 rotates faster than axle 35 on outward rotations of the winch, because: on outward rotations, the first overrunning clutch 29 is engaged, directing rotational power through gear transmission systems 17 and 33, whilst the second overrunning clutch 34 is disengaged. On spooling in the winch, the two axles rotate at the same speed, because then they are interconnected directly by the second overrunning clutch 34, which now is engaged, whilst the first overrunning clutch 29 is disengaged.
• Gear transmission system 33 may be omitted, thereby improving the efficiency of the mechanical energy transmission- and conversion system in cases where the extra gear transmission system 33 is considered unnecessary, provided that the rotary direction of the output shaft 24 of gear transmission system 17 is not reversed.
• the transmission of rotational power from axle 24 to axle 26 could then be achieved by a belt drive or a chain drive.
• a drive may be omitted, and the axles 24 and 26 merged into one, provided that axles 35, 25 and 27 with the gear transmission system 17 and the corresponding slip clutch 16 and overrunning clutches are designed and arranged so that the axles 24 and 35 are aligned with their centre line along the same line. This could be accomplished by using an epicyclic gear system and by employing hollow axle-cylinders and having axles enclosed in each other.
• the hydraulic subsystem The hydraulic subsystem
• the hydraulic subsystem 21 comprises in the embodiment of figure 1 the parts listed below.
• the parts are coupled together by hydraulic pipes or hoses, arranged as shown in the hydraulic diagram of figure 1 :
• an accumulator 8 containing a compressible fluid (e.g. nitrogen gas) which cannot escape the accumulator, so that that compressible fluid is forced to be compressed when fluid is pumped into the accumulator.
• a pressure limiting valve 6 which under normal circumstances is closed, so that fluid pumped by pump 3 or pump / motor 11 cannot escape anywhere but through the hydraulic power-take-off motor 10, but which opens when the pressure in accumulator 8 increases to a certain level, then allowing fluid pumped by the pumps to bypass the hydraulic power-take-of motor, conducting the pumped fluid straight back into the fluid reservoir 1.
• a flow control 31 between the accumulator 8 and the smaller pump / motor 11 that can be used to control the flow of fluid from accumulator 8 to pump / motor 11 when pump / motor 11 acts as a motor
• a check valve 32 allowing fluid pumped from pump / motor 11 to bypass flow control 31 when pump / motor 11 acts as a pump.
• a sequence valve 30 blocking fluid from flowing from the accumulator 8 and/or the pumps 3 and 11 into power-take-off motor 10 at pressure below a certain minimum threshold, but allowing it to flow at pressures above that threshold.
• a flow control 9 providing for a smooth and constant flow of fluid into the power take off motor, and also allowing the flow of fluid into the power-take-off motor to be regulated externally, manually or automated.
• a level/temperature gauge 2 • an atmospheric pressure fluid reservoir 1 supplying pump 3 and 11 with fluid when pumps are activated
• the hydraulic subsystem contains fewer parts: there is only one pump 22, with a larger displacement, like pump 3 in the embodiment according to figure 1.
• the pump 22 is connected to the output shaft 26 of the mechanical energy conversion subsystem, according to figure 5.
• the pump 22 also serves as a motor, winding in and tightening the winch, like pump / motor 11 in the embodiment according to figure 1.
• the mechanical energy conversion system now contains a variable gear transmission mechanism with two reversely coupled overrunning clutches 29 and 34 and a step-up gear system 17, 33 functional only on outward rotations of the winch, the effect of the pump 22 acting as a motor when spooling in the winch wire, is as though it had a lower displacement.
• a double-pipeline with a flow control 31 in one of the courses and a check valve 32 in the other course mounted in the same direction as check valve 7 in the embodiment according to figure 1, may optionally be included between the pump 22 and the accumulator 8 to control the activity of pump 22 when operating as a motor.
• the hydraulic subsystem powers a generator 28.
• One of the problems of exploiting wave energy is that the energy is unevenly distributed over short periods of time.
• a buoyancy body can only absorb energy in a part of the wave cycle.
• a generator needs a steady and invariable power input, in order to function optimally and to be able to generate electric power at required quality.
• a steady power input to the generator is provided by the accumulator 8 and optionally the flow control 9.
• the accumulator temporarily stores energy from the waves, so that it can be produced as a steady stream of fluid by the power-take-off motor 10.
• the accumulator inherently helps to equalize the differences.
• a flow control 9 can be employed to stabilize the speed of the power-take-off motor further.
• Stabilizing the speed of the power-take-off motor regardless of the pressure in the accumulator may be accomplished by using a variable displacement motor as the power-take-off motor 10, where the displacement is controlled and adjusted by mechanical, hydraulic or electronic feed-back-mechanisms based on measuring the speed of the generator 28, by means well known to engineers.
• the power-take-off motor and the generator together will have great flexibility to drain out a wide range of power rates from the accumulator 8. This may make the system efficient in a wide range of different wave conditions.
• the winch in the invention described herein is self- tightening.
• the arrangement of hydraulic and mechanical components provides for this.
• the accumulator 8 maintains a certain minimum pressure thanks to sequence valve 30.
• the pressure from the accumulator will power the smaller hydraulic pump / motor 11, now acting as a motor, causing the winch 12 to rotate inwards, tightening the wire.
• Due to the one-way clutch 29, the larger pump 3 will, unlike the smaller pump / motor 11, not rotate inwards with the winch.
• the winch When the wave forces are strong enough to overcome the spool-in force from the pump / motor 11, the winch will rotate outwards, causing both the larger pump 3 and the smaller pump / motor 11 to rotate with the winch, pumping fluid from fluid reservoir 1 into the accumulator 8.
• the smaller pump / motor 11 preferably has a lower displacement than the larger pump 3.
• the basic principle for protecting the plant, and the parts and subsystems contained in it, against overload, is simple: When the amount of wave energy per time unit which encounters the buoy is excessive, the buoy simply does not absorb that energy. This is made possible by designing an energy conversion and absorption system which inherently limits the amount of energy per time unit that can be channelled into the system.
• the wave- power plant should be capable of withstanding the worst extreme waves because it does not try to resist the waves when the wave forces therein become too great, but instead gives way and allows most of the power in the extreme waves, the destructive energy peaks, to pass and remain in the sea.
• the proposed overload protection mechanism is engaged by a hydraulic pressure- limiting valve 6 in the hydraulic subsystem.
• the pressure limiting valve 6 will open, allowing the pump(s), 3 and 11, or 22, to discard the extra energy input which otherwise could damage the wave-power plant, by directing the flow of fluid from the pump(s) straight back into the reservoir 1, bypassing the power-take- off pump 10.
• the pipeline(s) or hose(s) leading from the pump(s), 3 and 11, or 22, through the pressure-limiting valve 6 to the reservoir 1, and the pressure-limiting valve itself, have to be sufficiently wide, to accomplish this.
• the hydraulic overload protection arrangement described above will set a maximum limit for how of high pressure the hydraulic system can be exposed to, provided that the check valve 7, the pressure limiting valve 6 and the pipes or hoses leading from the pumps 3 and 11 back into the reservoir 1 are dimensioned correctly.
• This arrangement will, however not limit the speed which the pumps 3 and 11 and the mechanical energy conversion subsystem 20 and the components in it, may be exposed to, caused by the wave motions.
• a mechanical slip clutch 16 can be applied. This slip clutch is set to slip if the rotational speed or the torque transferred through it becomes to high. The slip clutch may be disengaged in events of extreme waves to protect the internal system from excessive speed, excessive forces and excessive energy input. Cone shaped winch cable drum
• the winch tightening system should ensure that the winch wire 14 is tight at all times. However: during operation, special events may occur, which make the winch wire slow. This may for example happen when the buoy finds itself on top of a breaking barnwave followed by another sympatheticwave. A slow wire is a problem. The wire is likely to wind in on the winch in a messy way in situations like that, and this may lead to greater wear and tear. To ensure that the wire is arranged properly again on the winch cable drum, after it has become disorganized by sympathetic waves slowing the wire, a conical winch cable drum, as shown in figure 4, may be applied.

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• 2008
  • 2008-10-17 NO NO20084372A patent/NO329152B1/no not_active IP Right Cessation
• 2009
  • 2009-10-12 EP EP09737187A patent/EP2347120A2/de not_active Withdrawn
  • 2009-10-12 WO PCT/NO2009/000355 patent/WO2010044674A2/en active Application Filing

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