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Fluid-driven power plantFluid-driven power plant description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20090169382, Fluid-driven power plant. Brief Patent Description - Full Patent Description - Patent Application Claims
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. The invention is directed to a power plant that harnesses kinetic energy of a moving fluid to rotate a shaft. The 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. One 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. Continue reading about Fluid-driven power plant... Full patent description for Fluid-driven power plant Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Fluid-driven power plant patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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