FLUID-DRIVEN POWER PLANT
A fluid-driven power plant for harnessing power from a fluid flowing in a preselected direction has a shaft mounted for rotation about a primary axis substantially perpendicular to the preselected direction and at least three blades attached to the shaft, each of the blades having a frame and at least one panel hingedly attached to the frame, with no more than two of the blades attached to the shaft at any particular axial position along the shaft. In specific embodiments, each of the at least three blades is attached to its frame at a location radially outwardly from the shaft for rotation about an axis substantially parallel to the primary axis. Two of the blades may be attached to the shaft at a first axial location along the shaft and two other blades may be attached to the shaft at a second axial location along the shaft.
This application claims priority to U.S. Provisional Application Ser. No. 61/009,232, filed on Dec. 27, 2007, the entire content of which is hereby incorporated by reference for all purposes.
FIELD OF THE INVENTIONThe invention is directed to a power plant that harnesses kinetic energy of a moving fluid to rotate a shaft.
BACKGROUND OF THE INVENTIONThe technique of harnessing the energy of a moving fluid to rotate a shaft is known. In some power plants, a vertical shaft is rotated by the action of fluid impinging on blades vertically attached to the shaft. Such a device rotates when fluid resistance on one side of the axis of rotation exceeds the fluid resistance on the other side. Fluid resistance of the device increases with exposed blade area. In devices with solid, flat blades, the fluid resistance on each side is equal, so in a uniform fluid flow the device will not spin. Some known designs addressing this issue use blades that automatically change configuration during the rotational cycle to maximize the difference in fluid resistance between opposite sides of the device. One example of this is disclosed in U.S. Pat. No. 17,168 to R. Nutting.
A device having only two such blades situated 180° from each other may become stationary when both blades are parallel to the fluid flow. Devices such as these depend on inertia to carry the blades through this “dead zone” in the cycle, but starting the device from the “dead zone” position or operating the device in slow fluid flow is difficult. To address this issue, some devices have more than two blades so that there is always at least one blade receiving some force from the impinging fluid. Such a device is disclosed in U.S. Pat. No. 611,874 to W. Turner. A disadvantage of this design is that the blades partially shield each other from the impinging fluid, thereby limiting efficiency. For example, in a device with four evenly spaced blades, a blade in a “positive” position may experience the force of the fluid flow across the entire area of its face, and move accordingly, thus rotating the entire device. A blade perpendicular to the fluid flow such that it receives the maximum force from the water may be considered to be in the “positive” position for these purposes. However, once the device rotates even slightly, an adjacent blade begins to shield the first blade, so only a fraction of the available area of the first blade is exposed to the fluid flow. In addition, some devices of this type depend on forces from the fluid itself to automatically change the blade configuration throughout a cycle. In such devices, the shielding effect from adjacent blades may adversely affect this automatic adjustment.
SUMMARY OF THE INVENTIONOne embodiment of the invention is a power plant having a vertical shaft with blades hinged to provide maximum exposed blade area while in the positive position. The blades switch automatically to a configuration with minimal exposed blade area when moving against the current to complete a cycle or revolution. In one embodiment, at least three blades are positioned on the shaft such that there are at most two blades at any attachment point on the shaft. In the case of two blades at a single attachment point, the blades are situated 180° from each other. Having only single blades or pairs of blades at each attachment point ensures that each blade receives the full force of the impinging fluid flow since the blades do not shield each other. The other blades are displaced axially along the shaft and are offset from the first group such that the shaft always has at least one blade in a position to receive force from the impinging fluid without a “dead zone.”
Each blade is composed of a frame and at least one pivoting panel. The frame may be attached vertically to the shaft. The panel is attached to the outer vertical edge of the frame with a hinge, allowing the panel to swing up to 180° away from the frame. In the positive position, the panel is fully closed such that the force of the impinging fluid holds the panel flush against the frame. As the blade moves with the fluid flow and the shaft rotates, the inside edge of the panel catches the fluid flow, which swings the panel away from the frame. By the time the blade moves 90° from the positive position, the panel has moved 180° away from the frame under the influence of the fluid and is then parallel to the fluid flow. The panel stays parallel to the fluid flow until the blade points directly upstream. At this time, the panel is once again flush against the frame and remains in this configuration by the force of the impinging fluid while the power plant moves through the positive position of the panel. The freely-swinging panel allows for significantly less drag as the blade moves upstream to complete a given cycle (or revolution) since the fluid resistance comes only from the frame which has a significantly smaller area than the panel. The large difference in fluid resistance between panels on opposite sides of the device greatly increases the efficiency of the apparatus.
More specifically, a fluid-driven power plant according to the invention for harnessing power from a fluid flowing in a preselected direction has a shaft mounted for rotation about a primary axis substantially perpendicular to the preselected direction and at least three blades attached to the shaft, each of the blades having a frame and at least one panel hingedly attached to the frame, with no more than two of the blades attached to the shaft at any particular axial position along the shaft. In specific embodiments, each of the at least three blades is attached to its frame at a location radially outwardly from the shaft for ratation about an axis substantially parallel to the primary axis. Two of the blades may be attached to the shaft at a first axial location along the shaft and two other blades may be attached to the shaft at a second axial location along the shaft.
The present invention is directed to a power plant for harnessing the energy of a moving fluid to rotate a shaft, the device having high efficiency and a simple design. As complicated devices have more opportunities for failure, a simple design is especially advantageous for applications such as fluid-driven power plants, where the blades may be difficult to access for repair. Furthermore, any downtime in operation affects the operability of other devices that depend on the power plant for energy.
One embodiment of the invention uses water as the driving fluid. Moving water naturally occurs in many forms, including ocean currents, ocean waves, stream currents and tidal flows. Harnessing the energy in moving water is an efficient and environmentally-sustainable method of generating power. Other driving fluids include air streams such as wind, or water jets in air such as waterfalls or blowholes.
The rotating shaft of the power plant may be connected to any of a variety of different devices to harness the kinetic energy of the fluid flow. For example, connecting the power plant to a generator or alternator converts the rotational energy of the shaft into electricity. Coupling the shaft to a mechanical device using gears or belts harnesses the kinetic energy to drive the device. Attaching a reciprocating pump to transport a fluid against gravity converts the kinetic energy into potential energy. Because the power output may be adjusted by changing the number and size of the blades, a fluid-driven power plant such as the present invention is adaptable to a wide variety of applications.
Referring now specifically to
The plurality of blades 18 are divided into groups 22 of one or two blades each, with only one group 22 being attached to any one vertical (or axial) section of the shaft 10. In the case of 2 blades 18 per group 22, the blades 18 are displaced 180° apart about the primary axis of the shaft 10. Each subsequent group 18 is attached to a different vertical (or axial) position on the shaft 10, and is offset angularly from at least one other group 18. When considering all of the blades 18, the largest gap between any two blades 18 rotating about the axis 10 should be less than 180°. This requires a minimum of 3 blades 18 in at least 2 vertically-stacked groups 22. In this embodiment, no blade 18 is shielded by another and the device as a whole then does not have a “dead zone.” In one particular embodiment, the blades 18 of one group 22 may be displaced 90 degrees from the blades 18 of an adjoining group 22, as illustrated in
Radial symmetry allows the device to operate in the same manner regardless of the direction of fluid flow 20, as long as the fluid flow is substantially perpendicular to the primary axis 10a of the shaft 10. For example, if the device is situated below the surface of the ocean in a location to take advantage of wave energy, the device spins in a clockwise direction when the wave comes in to shore, as well as when the wave retreats. Because the change in configuration of the blade 18 is determined by the fluid forces on the panel 14, the device adjusts automatically to changes in the direction of the fluid flow 20.
The panels 14 may be made of any rigid or semi-rigid material such as wood, metal, or plastic. A non-corroding material, stainless steel for example, is best for salt water applications. The panel 14 may be solid, or may contain one or more hinges to create a flexible structure. The pivot point hinge 16 may be at the outer edge of the blade 18, or may be located anywhere along the length of the blade 18, as long as that location is radially outwardly of the primary axis 10a of the shaft 10. The blade 18 may also have multiple panels 14 that behave in the same or similar manner as a larger single panel 14.
Referring to
Referring to
Thus, the disclosed structure can be configured to take full advantage of the water flow available. If a river, creek, aqueduct or other current is ten (10) feet deep, then five (5) rows of two (2) foot tall panels could be interconnected using the couplings 26 and the cage linkage mechanisms 28 to fully utilize the available water flow. A single generator, alternator, pump or other mechanism can then be positioned at one end of the shaft, typically the upper end, to convert the kinetic energy of the water flow to electricity or other suitable form of energy, as set forth in
Referring now to
Alternatively, as illustrated in
In another embodiment, the device is tilted slightly away from the primary direction of the fluid flow 20. This takes advantage of gravity to assist in keeping the panel 14 flush against the frame 12 from 6 o'clock to 12 o'clock in the first half rotation of the device. This is particularly helpful in slow fluid flow conditions where the panels 14 might otherwise have a chance to drift open during this portion of the cycle.
The foregoing description has provided by way of non-limiting examples a full and informative description of the exemplary embodiments of this invention. However, various modifications and adaptations may become apparent to those skilled in the relevant art in view of the foregoing description, when read in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications of the teachings of this invention will still fall within the scope of this invention. For example, the disclosed power plant may rotate about a non-vertical axis, if desired, and the rotatable blades may be mounted differently than disclosed, without deviating from the scope of the invention. Likewise, the number and arrangement of the blades, frames and coupling mechanisms may vary.
Claims
1. A fluid-driven power plant for harnessing power from a fluid flowing in a preselected direction, comprising:
- a shaft mounted for rotation about a primary axis substantially perpendicular to the preselected direction;
- at least three blades attached to the center shaft, each of the blades comprising a frame and at least one panel hingedly attached to the frame; wherein no more than two of the blades are attached to the shaft at any axial position along the shaft; and
- a structure for connecting to the center shaft.
2. The fluid-driven power plant of claim 1 wherein
- each of the at least three blades is attached to its frame at a location radially outwardly from the shaft for rotation about an axis substantially parallel to the primary axis.
3. The fluid-driven power plant of claim 2 further comprising at least four of the blades,
- two of the blades being attached to the shaft at a first axial location along the shaft; and
- two of the blades being attached to the shaft at a second axial location along the shaft.
4. The fluid-driven power plant of claim 3 wherein
- the two blades attached to the shaft at the first axial location are displaced 180 degrees from one another about the shaft.
5. The fluid-driven power plant of claim 4 wherein
- the two blades attached to the shaft at the second axial location are displaced 180 degrees from one another about the shaft and are displaced 90 degrees from the respective blades attached to the shaft at the first axial location.
6. The fluid-driven power plant of claim 1 further comprising
- a coupling mechanism on the shaft and configured to couple more than one fluid-driven power plant for common rotation.
7. The fluid-driven power plant of claim 6 wherein
- the coupling mechanism is configured to stack a plurality of fluid-driven power plants for rotation together about the primary axis.
8. The fluid-driven power plant of claim 1 further comprising
- a cage supporting the fluid-driven power plant.
9. The fluid-driven power plant of claim 8 further comprising
- a cage linkage mechanism configured to connect the cage of the fluid-driven power plant to the cage of another fluid-driven power plant.
10. The fluid-driven power plant of claim 1 wherein the primary axis of the fluid-driven power plant is tilted away from the preselected direction of fluid flow.
Type: Application
Filed: Dec 29, 2008
Publication Date: Jul 2, 2009
Inventor: Willis Bond (Pahrump, NV)
Application Number: 12/345,655
International Classification: F04D 29/24 (20060101);