Wave action energy converter uses float connected to electric generator, which is anchored on sea bed

Office for the © 1016103

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© Patent application: 1016103 © Filed: 05.09.2000 © lnt.CI.⁷

E02B9 / 08, F03B13 / 18, F03B13 / 10

<td>@ Signed up:</td><td>© Patent holder (s):</td>

<td>07.03.2002 IE 2002/05</td><td>First Design BV in Enschede.</td>

<td>@ Date:</td><td>© Inventor (s):</td>

<td> 07.03.2002</td><td>Hans Georg Jerie in Enschede</td>

<td>© Published:</td><td>® Authorized representative:</td>

<td>01.05.2002 IE 2002/05</td><td>Ir. BJ 't Jong et al. At 2502 EN The Hague.</td>

© Device for generating electricity from wave movements.

The invention relates to a device for generating electricity from energy of wave motion of a water body, comprising: an anchoring; a pressure chamber with gas therein, wherein the device in use is at least partly immersed in the water body and experiences an upward force, which pressure chamber comprises two chamber parts movable relative to each other and connected in airtight and watertight manner, such as a cylinder and a piston placed therein, wherein a first of the chamber parts is connected to the anchor and a second of the chamber parts is movable to and from the first of the chamber parts in use of the device under the influence of the wave energy; and a generator arranged to generate electricity from relative movement of the chamber parts, further comprising: arresting means which, for a period of time, maintain the first and second chamber parts at least approximately in a relative position corresponding to an extreme of a wave movement, in essentially until a next, opposite extreme of the wave movement reaches the device.

NL C 1016103

The contents of this patent correspond to the original filed description with claim (s) and any drawings.

Apparatus for generating electricity from wave movements

The present invention relates to a device for generating electricity from energy of wave motion of a water body. Such a device, as it is known, comprises an anchoring; a pressure chamber with gas therein, wherein the device in use is at least partially immersed in the water body and experiences an upward force, which pressure chamber comprises two chamber parts movable relative to each other and connected in airtight and watertight manner, such as a cylinder and a piston placed therein , wherein a first of the chamber parts is connected to the anchor and a second of the chamber parts is movable to and from the first of the chamber parts in use of the device under the influence of the wave energy; and a generator arranged to generate electricity from relative movement of the chamber parts.

The drawbacks of the existing devices are that, as a result of the waves imposed by them ......

motion, which is approximately a harmonic motion, have a more or less oscillating motion pattern, which requires the property vibration of the device to be adapted to the wavelength of the waves. This means either that the existing devices have an optimal operation at one specific wavelength (of course the most common wavelength) and yield a lower efficiency at other wavelengths, or that a costly and / or technically complex control is required to achieve the dynamic properties of adapt the device to the instantaneous wavelength. According to patent NL 1006933, the latter is realized by the volume of the

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make the gas-filled space variable, so that the spring constant of the system can be changed.

In normal use, i.e., power generation, it is desirable that the device operate as close as possible below the liquid surface since the pressure differences due to the hydrostatic pressure differences close to the surface are greatest; as the depth increases, the pressure differences due to the waves will be less present. However, this cannot be achieved in practice, because close to the liquid surface there is also the potentially harmful force of wave action during storms. For this reason, the known devices are either placed deeper below the surface, resulting in a lower efficiency, or very heavy and strong, with a negative cost effect.

The positioning of such a known device at sea is not only determined by its favorable location relative to the prevailing waves and the required minimum depth, but also by the possibility of building a foundation in the sea on site. This also means that a trade-off must always be made between non-optimal returns and high costs for difficult construction sites. For the regular maintenance that every mechanical system needs, divers must be underwater ......

provide access to the facility, or in some cases the facility itself is towed back to shore, with all associated costs.

The object of the present invention is to solve or at least alleviate the above-mentioned problems of the known device, for which purpose a device according to the present invention is provided, which is distinguished by arresting means which, for a period of time, at least approximately the first and second chamber parts maintain a relative relative to an extreme of a wave movement, mainly until before a next one, opposite extreme of the wave movement reaches the device.

It has been realized with a device according to the present invention that its operation becomes independent of the wave characteristics of the harmonic movement of the wave movement of the water body. Namely, the harmonic characteristics of the wave movement are converted into a periodic, non-harmonic movement of the chamber parts relative to each other. Adjustment of the self-vibration of the device is hereby unnecessary and optimum efficiency is achieved for all occurring wave characteristics.

Moreover, a device according to the invention can be designed very simply and robustly, without the need for a heavy foundation to be built in the sea, whereby the device can be positioned close to the water surface of the water body in order to optimally influence the influence of the wave movement of experience the body of water. Preferably, the locking means give relative movement of the chamber parts rather shortly after the wave movement has passed the average water level height. This release point is expected to result in optimum efficiency in conjunction with the inertia of the system.

As the hydrostatic pressure differences increase, the pressure chamber is affected by this, tending to shrink oni, the chamber parts moving towards each other to reduce their volume. With the locking means the movement of the two chamber parts relative to each other is stopped or at least slowed down for a predetermined time. This increases the pressure difference between the internal pressure in the pressure chamber and the fluid pressure due to the wave movement. When the movement of the chamber parts relative to each other is released, this will take place with an increased force relative to the situation with known free-oscillating systems, so that a movement of the two chamber parts over a greater distance relative to each other and a higher returns can be achieved.

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In addition, the detent means are selectively actuable, preferably in a condition with the chamber members at an approximate maximum distance from each other to allow access to the pressure chamber for maintenance and / or inspection without risk. The detent means should then be insensitive to the waves and thus be energized more strongly and continuously instead of the above-described temporary braking application. The locking means can be designed jointly or separately for each of the above-described applications.

In a preferred embodiment, the device comprises pressure means connected to the interior of the pressure chamber, which are arranged to adjust the pressure in the pressure chamber in use. Although with the locking means according to the present invention the spring constant of the device determined by the pressure in the pressure chamber is considerably less relevant for achieving an optimum efficiency, which depends on the known devices of the relationship between this spring constant and the wave characteristics of the wave impact. of the water body, in some cases it may be desirable to set the internal gas pressure in the pressure chamber. This also to control the spring constant of the device according to the invention.

It may also be desirable to adjust the pressure in the pressure chamber when maintenance is desired or to adjust the pressure after changes have occurred, e.g., due to temperature changes. By increasing the pressure, the distance between the two chamber parts increases and the second of the chamber parts can be brought to the surface of the water body at a stationary first of the chamber parts. In addition or as an alternative to this embodiment, an entry and exit, such as a hatch, is provided for maintenance personnel near the top thereof, no divers need to be used to reach the device or the device need not be towed ashore to become. The second of the chamber parts is simply brought to the water surface, after which maintenance personnel can carry out maintenance by opening the hatch in the interior of the pressure chamber. After maintenance, the hatch can be closed and the pressure can be brought to a desired value to bring the chamber parts back together, the second of the chamber parts sinking again.

An apparatus with the aforementioned pressure means of the present invention may include an air conduit to the surface of the water body to control pressure within the pressure chamber in conjunction with the pressure means, e.g., a pump.

Particularly in connection with the ability to bring the second of the chamber parts to the water surface, it may be elongated and extend upward.

In one embodiment, the second chamber part can comprise a bellows construction, which is pliable and can in principle better absorb potentially harmful influence of the wave.

In a particularly favorable embodiment, as defined in claim 15, an optimum efficiency of the point-absorbing effect known in the art is obtained. The device can have a free stroke of 13 m and one with an internal volume of between 18 and 20 m³ have a consistent length per square meter of surface.

The invention will be further described by way of embodiments with the above and other properties, advantages and options thereof, as shown in the attached drawing, in which: Fig. 1 shows a partly cut-away perspective view of a first embodiment;

fig. 2 shows a partly cut-away perspective view of a detail from fig. 1;

Fig. 3 shows a schematic representation of the movement of a device according to the invention under the influence of wave action;

Fig. 4 shows another embodiment of a device according to the present invention;

Fig. 5 shows a view of an interior of a device with locking means according to the present invention; and fig. 6 shows a schematic top view of an interior with locking means in a device fig. 5.

In the figures illustrating various embodiments of devices according to the present invention, like or like components are designated by like reference numbers.

Fig. 1 shows a device 1 according to the invention. The device 1 comprises a cylinder 2 with a piston 3 movably arranged therein. The cylinder 2 and the piston 3 form respectively. one of the chamber parts of the pressure chamber, which is enclosed by the cylinder 2 and the piston 3.

In this pressure chamber 4 enclosed by the cylinder 2 and the piston 3, gas is brought under a certain pressure. This gas can be, for example, outside air, which pressure medium is formed in the piston 3 via an air line 6 arranged on a buoy 5, not as, for example, a pump (not shown). With such a pump (not shown), the pressure in the pressure chamber can be set, not only during installation, inspection or inflation from the safe storm position, in which cylinder 2 is withdrawn as far as possible from the potentially harmful influence of the water surface, but also to compensation of, for example, pressure changes caused by temperature variations.

In the embodiment shown here, the piston 3 is stationary and connected to an anchor cable 7, which is connected at the end opposite the device 1 to an anchor designed as a weighted 8.

As also shown in Figs. 2, 5 and 6, a number of, here four, rack tracks 9 are arranged in the interior of the cylinder 2, along which, for example, gears 10 coupled together with cardan shafts 28 to the piston 3 run during an up and down movement. / or downward movement of the cylinder 2 relative to the piston 3. The gears 10 or the cardan shafts 28 are connected via a belt 11 or, for example, a chain to a flywheel 12 comprising generator 13.

Additionally or alternatively, chains can be used to couple the gears 10 to the generator 13. Other gears and generators can also be used to control the relative movement of the cylinder 2 - the second of the chamber parts - and the piston - the first of the chamber parts - convert into electrical energy.

Figures 2 and 5 show side views of an exemplary embodiment of the drive of the actual generator 18, in which flywheels 12 comprising an assembly is coupled to the belt 11 or to a chain connected to the sprockets 10, which assembly is provided with a actual generator 18 connected drive shaft 19. The flywheels 12 are aligned with a shaft 20.

Fig. 6 shows a top view of an interior of the device 1 shown in FIG. 5 along line VI-VI and in assembled condition.

Fig. 2 also shows a seal 21 for an airtight and watertight seal or water barrier between the cylinder 2 and the piston 3, which is designed as a rolling membrane 21.

Fig. 3 schematically shows the course of movement 23 of a cylinder 2 with respect to a piston 3 in the configuration of the device according to Figs. 1 and 2 under the influence of a wave movement 22. It appears clearly that with the locking means to be described below the cylinder 2 has a delay in reaching the extreme position relative to the piston 3.

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especially up to point 24 along the course of the movement

23. This applies both to the upward and downward movement of the cylinder 2 relative to the piston 3. A movement course 23 is thus obtained, which is not harmonious, but is at least approximately periodic. Because the cylinder 2 does not follow the harmonic of the wave movement 22 closely, but distils the periodic characteristics from it by the action of the locking means, the inherent vibration of the device 1 does not have to be accurately tuned to the wave characteristics of a wave movement prevailing at a given moment to obtain an optimal return.

It is noted that in Fig. 3 the relationship between the wave movement 22 and the movement course 23 of the device is only schematically shown.

It can be clearly seen from Fig. 3 that near the extremes in the course of movement 23 of the device according to the invention no or very little movement can be detected in the device for a certain period of time. In order to ensure that the actual generator 18, as shown in Fig. 2, is also driven during these dead times, the flywheels 12 are provided.

The devices can be positioned side by side. The establishments operate independently .....

each other and can be placed at any distance and position from each other. The electrical conductors 25 in Figs. 1 and 4 can then be led to a common node, from which the electricity generated by the individual devices 1 is fed, for example, via a common conductor to the shore.

Fig. 1 and 2 schematically show embodiments of a device according to the invention, in which an inlet and outlet designed as hatch 26 is arranged on the top of cylinder 2. By increasing the pressure in the pressure chamber 4, it is possible for the cylinder 2 to rise relative to the piston 3 to a mutual positioning, the hatch being above the water surface of the water body. A person can then open the airtight and watertight sealed hatch 26 for maintenance or inspection at a pressure in the pressure chamber 4 at an equal value to the outside world. Therefore, the device does not need to be towed ashore for maintenance and no divers are required. Preferably, the detent means are then energized to avoid risks of the device moving while a person is inside.

It should be noted that in the foregoing the piston 3 in each case remained substantially stationary with respect to the reciprocating cylinder 2. It should be noted that this division of tasks can also be easily reversed, for example by forming a separate pressure chamber in the cylinder . Completely different configurations of the pressure chamber are also possible, for instance one, in which piston 3 continues in a movement opposite to that of cylinder 2. Thus, further in fig. 4 a configuration with a bellows 27 is shown. Here, a rack and pinion track 32 fixedly connected to the top of the bellows extends through the interior of the bellows 27 and, when the top of the bellows 27 moves up or down, the flywheels are driven, to which end the shaft 20, which is between the flywheels 12 run, for example, is a keyway on which the rack and pinion track 32 engages. The flywheels, in turn, are connected to the actual generator 18, with which electricity can be generated to be discharged through the electrical conductors 25.

Figures 5 and 6 schematically show an interior of a device according to the invention, with locking means for realizing the operation shown diagrammatically in Figure 3.

To this end, lock 29 is provided, which in this exemplary embodiment is a disc 30 of a disc brake 31. The disc 30 is mounted on the cardan shaft 28, and the rest of the disc brake 31 is attached to the piston 3 for movement of cylinder 2 and piston 3 relative to to arrest each other. Alternatively, an electric motor with a gear wheel can be used, which directly engages rack and pinion track 9 of cylinder 2 or acts on one of the gear wheels.

The lock 29 fixes cylinder 2 and piston 3 during a portion of the up and down strokes of the wave movement as shown in Fig. 3., and provides movement of cylinder 2 and piston 3 relative thereto before reaching of a next extreme in the wave movement, free. The block 29 with disc brake 30, 31 or an electric motor (not shown) can be supplied with electricity by generator 18.

Alternatively, a resilient mechanical element from piston 3 can engage cylinder 2, or vice versa, to lose engagement and release movement when exceeding a force corresponding to the hydrodynamic pressure. Thus it appears that the skilled person will, after taking note of the foregoing in connection with the invention, recognize many alternative or additional embodiments for the locking means, without having to perform any inventive work himself.

The design of the device, in contrast to the existing techniques, allows a simple and cheap installation. The devices float in the sea, so they can be towed, while the sinking can be done by temporarily adding extra ballast. Since no foundation is needed but only an anchor or counterweight, no underwater construction activities are required. The anchor can be sunk and then filled with sand, rubble or scrap.

To enable a simple and cost-conscious installation, the following preferred procedure for installing one or more wave energy converters should be used:

1. Determine the approximate location for the establishment on the map (one or more establishments).

2. Find the right place at sea by searching for the correct depth by means of sonar.

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3. The correct location is determined by coordinates, for example using GPS.

4. A cable / chain of the correct length for attaching the device is attached to the anchor / counterweight to be used. A buoy is fitted to give the cable / chain buoyancy.

5. The anchor / counterweight has sunk in the intended position of the device in the previous step, and is then (if necessary) weighted. This anchor / counterweight is itself preferably a light, open box, which, once in place, is weighted with debris, scrap, etc.

6. Provisions for taking off electricity generated by the establishment are provided.

7. The device is now maneuvered above the anchor, and then temporarily weighted with ballast, so that the device will sink slowly.

8. Once the device has fallen to the correct depth, a diver attaches the cable / chain to the device, as well as the electrical connection.

9. The temporary ballast of the device can now be removed, as well as the buoy attached to cable 7.

10. The device is now ready for use.