Power plants – Pressure fluid source and motor – Utilizing natural energy or having a geographic feature
Reexamination Certificate
2000-05-19
2001-07-10
Ryznic, John E. (Department: 3745)
Power plants
Pressure fluid source and motor
Utilizing natural energy or having a geographic feature
C060S496000
Reexamination Certificate
active
06256985
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a device for energy conversion from wave movement in water, comprising a frame connectable to a seabed, a container for containing a gas, which container is formed by at least two parts, a first part connected to the frame and a second part displaceable in vertical direction relative to the first container part for varying the working volume of the container, and energy converting means for energy conversion from the displacement of the second container part.
2. Description of the Prior Art
There exist wave energy converters which have a gas-filled container which is situated below the water surface. Due to wave movements on the water surface pressure differences will occur periodically under the water surface. The pressure differences result in vertical movement of the gas-filled container, which movement can for instance be converted to drive a generator. Such an apparatus is disclosed in GB 1 604 372 with a first tank member which moves relative to a second buoyant tank member. The tank members cooperate in a gas tight manner such that compressed gas or partial vacuum may be used as a source of power. The existing wave energy converters are optimized for energy conversion at a determined, frequently occurring wavelength which is generally local. When wavelengths differ, the efficiency of energy conversion is considerably lower than at the wavelength for which the converter has been optimized.
SUMMARY OF THE INVENTION
The present invention has for its object to provide a wave energy converter of which the adjustment can be optimized for varying wavelengths. In addition, the device must have a simple construction.
The invention provides for this purpose a device for energy conversion from wave movement in water according to the type disclosed above, characterized in that, the device also comprises means for changing the range of the working volume of the container. The working volume of the gas-filled part of the container is varied by mutual movement of the parts of the gas-filled container. The range of the working volume of the gas-filled space thus determines at least partially the spring curve of the device. This spring curve can be influenced by changing the range of the working volume of the gas-filled part of the container. The desired oscillation frequency is thereby variable and the optimal adjustment of the device can be varied for diverse wavelengths. The efficiency of this device is considerably greater than the efficiency of existing devices for wave energy conversion, particularly in an environment in which wavelengths of diverse lengths occur. Another advantage of the device is that it can be placed in solitary disposition, which makes the device useful for applications in which only a limited amount of energy is required. Yet another advantage is that structurally the device can be embodied in very simple manner.
Also GB 1 589 286 discloses a compression device using vertical motion of water according to the type disclosed above. The device includes a float chamber with a movable float so that when the float is acted upon the rise and fall of water motion the volume of the further chamber changes. The device according this patent also lacks means to vary the oscillation frequency.
The means for changing the range of the working volume of the container can be formed in a preferred embodiment by a conduit system with pump with which liquid can be pumped in and out of the container. The range of the working volume of the gas-filled part of the container is varied by feeding respectively draining liquid into and out of the container. The oscillation frequency of the device can thus be influenced in simple manner.
In another preferred embodiment the means for changing the range of the working volume of the container is formed by a displaceable wall part. This displaceable wall part is preferably connected to a cylinder for placing thereof in position as required. This displaceable wall part can be formed for instance by a plunger. The range of the working volume of the container available for gas is variable with such a displaceable wall part. It should be noted here that the displaceable wall part must connect gas-tightly, or at least close-fittingly, onto the inner side of the container since the working volume of the part of the container available for gas is otherwise not varied by displacement of the displaceable wall part. A simple solution herefor lies in a plunger construction, wherein a part of the container forms a cylinder wall onto which the plunger must connect in gastight manner. It will be apparent that the displaceable wall part has to be fixable in different positions to thus enable fixing of the part of the container intended for gas in the desired setting. Displacement of the displaceable wall part and fixing thereof can both take place using a cylinder.
The frame of the device is for instance connectable fixedly to the bottom. It is also possible however to connect the frame flexibly to the bottom. A fixed connection to the bottom has the advantage that the exact position of the device on the bottom is known. This is possible for instance by providing the frame with a heavy concrete socle. A lighter construction can suffice when the frame is connected flexibly to the bottom. What should be envisaged here is an anchoring in the bottom which connects to the frame with flexible elements. The advantage of such a construction is that it can take a lighter form.
A simple construction of the device is obtained when the container is formed by a vertically displaceable hood opened on the underside and a stationary lower container part which connects onto the opened side of the hood. A water barrier is preferably arranged between hood and lower container part. This water barrier can for instance be formed by a rolling membrane. When a water barrier is present, it is possible using this relatively simple construction to prevent uncontrolled change in the range of the working volume of the container available for gas. Account must be taken here not only of liquid flowing in and out of the container but also of evaporation which may be involved here.
The energy converting means consists in a preferred embodiment of at least one hydraulic cylinder, the liquid from which drives an electric generator. The hydraulic cylinder can be placed between the two container parts movable relative to each other such that the hydraulic system is activated at each mutual displacement of the container parts. Electricity for instance can hereby be generated in relatively simple manner. It is noted that the hydraulic cylinder is also a significant factor in effecting a determined amplitude of the oscillation. Further options for adjusting the oscillation frequency result by for instance arranging a mechanical spring or other spring between the container parts displaceable relative to each other.
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patent: 875042 (1907-12-01), Bissell
patent: 4207741 (1980-06-01), Rainey
patent: 4208878 (1980-06-01), Rainey
patent: 4284901 (1981-08-01), Giguere
patent: 4363213 (1982-12-01), Paleologos
patent: 4598211 (1986-07-01), Koruthu
patent: 4603551 (1986-08-01), Wood
patent: 5426332 (1995-06-01), Ullman et al.
patent: 1292638 (1991-12-01), None
patent: 1589256 (1981-05-01), None
patent: 1604372 (1981-12-01), None
patent: 9517555 (1995-06-01), None
Gardner Fred Ernest
Van Schie Rudolfus Gerardus
A.W.S.B.V.
Ryznic John E.
Webb Ziesenheim & Logsdon Orkin & Hanson, P.C.
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