Water engine, method for operating a water engine, and use of a water engine

Abstract

The present invention relates to a water turbine (1) with a water wheel (2), wherein the water wheel (2) comprises a core body (3) and a plurality of blades (4). The water turbine (1) also comprises at least one spacer (5) defining a minimum distance between the water wheel (2) and the bottom (6) of a body of water (7) at a location (8) where the water turbine (1) is to be used, and an energy converter (9) for processing the rotational energy of the water wheel (2). Furthermore, the invention relates to a method for operating a water turbine (1) comprising a water wheel (2), at least one first spacer (5), a first buoyancy body (10), and an energy converter (9), and to the use of a water turbine (1).According to the invention, the water turbine (1) is characterized in that the core body (3) of the water wheel (2) comprises a first buoyancy body (10), wherein the first buoyancy body (10) and the spacer (5) are dimensioned such that the water turbine (1) rests on the bottom (6) of the body of water (7) at a mean water level (MW) at the place of use (8), where the water turbine (1) is arranged in its intended use, and is buoyant at a water level above the mean water level (MW).

Description

[0001] The present invention relates to a hydropower machine with a waterwheel, wherein the waterwheel comprises a core body and a plurality of blades. Furthermore, the hydropower machine comprises at least one spacer that defines a minimum distance between the waterwheel and the bottom of a body of water at a location where the hydropower machine is used, and an energy converter for processing the rotational energy of the waterwheel. Furthermore, the invention relates to a method for operating a hydropower machine comprising a waterwheel, at least one first spacer, a first buoyancy body, and an energy converter, and to a use of a hydropower machine.

[0002] Such a hydropower machine is disclosed, for example, in DE 28 37 186 A1. The hydropower machine disclosed therein is operated by floating means. Floating hydropower machines, for example, have long been known under the term "ship mills." They typically consist of two floating bodies on which a waterwheel with a horizontal shaft is mounted. In the past, these ship mills, as the name suggests, served to drive mills located either on the structure itself or on the shore. More recent developments, usually known as "floating waterwheels" or "floating hydroelectric power plants," are based on the principle of these ship mills, but are usually used to generate electrical energy using a power generator.

[0003] These floating waterwheels utilize only the kinetic energy of flowing water, which causes the waterwheel to rotate due to the water flowing through the blade area. Consequently, the amount of energy that can be generated depends primarily on the flow velocity of the water. For economic reasons, the application of these floating waterwheels is limited to river sections with high flow velocities. These floating waterwheels usually have floats attached to the sides, which requires a particularly stable construction and results in a considerably higher weight.

[0004] The object of the present invention is to improve the known hydropower machines of this type, in particular to eliminate the disadvantages listed.

[0005] The problem is solved by a hydropower machine, a method for operating a hydropower machine and a use of a hydropower machine having the features of the independent patent claims.

[0006] The proposed hydropower machine comprises a water wheel, the water wheel having a core body and a plurality of blades, at least one spacer defining a minimum distance between the water wheel and the bottom of a body of water at a location where the hydropower machine is used, and an energy converter for processing the rotational energy of the water wheel. According to the invention, the hydropower machine is characterized in that the core body of the water wheel comprises a first buoyancy body, the first buoyancy body and the spacer being dimensioned such that the hydropower machine rests on the bottom of the body of water at an average water level at the location where the hydropower machine is arranged during intended use, and is buoyant at a water level above the average water level.

[0007] By locating the first float in the core of the water wheel, lateral floats are eliminated. This makes the construction lighter and more stable. The basic design is similar to the self-supporting body currently used in automobile construction.

[0008] In contrast to the previously described known floating hydropower machines, the hydropower machine according to the invention normally utilizes additional potential energy from the water body by operating on the bottom. This improves the hydropower machine's efficiency in energy conversion.

[0009] Only at higher water levels, when the water is floating, is the kinetic energy of the water body essentially utilized. This improves the efficiency of the hydropower machine in energy conversion. The hydropower machine is dimensioned in terms of its own weight and buoyancy forces so that it floats above a certain water level. The water body can, in principle, be any body of water with a current. However, the hydropower machine according to the invention is particularly suitable for use in rivers.

[0010] In Germany, for example, the mean water level (MW) of bodies of water is defined by the Federal / State Working Group on Water (LAWA). The water level is averaged over a certain period of time. This period can range from a few months to several years. Similar definitions probably exist for most countries in the world. However, it is also possible to determine a mean water level independently of official institutions using the method described above. A reasonable averaging period is at least 12 months to account for seasonal fluctuations.

[0011] The hydropower machine is dimensioned so that at the average water level at the installation site it rests on the waterbed with at least one spacer, for example, and the water surface is slightly below the lower edge of the first buoyancy body. This reduces unwanted escape of water volumes below the hydropower machine. When the water wheel is in operation, a damming effect is created, which increases the water level at the inlet. This must be taken into account when dimensioning the hydropower machine so that the damming effect alone does not prevent the hydropower machine from floating up. When the water level rises, for example after rainfall, the hydropower machine lifts off the waterbed and floats up, depending on the buoyancy forces of the first buoyancy body.

[0012] The spacer ensures that the hydropower machine maintains a defined distance from the waterbed, even at low water levels. The hydropower machine preferably has two spacers arranged to the side of the waterwheel. The hydropower machine can also, for example, include at least one support edge that rests on the waterbed.

[0013] The energy converted by the hydropower machine is then used for its intended purpose by the energy converter mounted on the hydropower machine. A generator, for example, can generate electrical energy, which can be transmitted, particularly via a connecting line, to the waterfront and used there. Alternatively, the mechanical energy of the waterwheel can be used directly, for example, for water or air pumps. The energy converter can therefore be designed, in particular, as a generator, water pump, or air pump.

[0014] For the hydropower machine, it is advantageous if the core body has a polygonal cross-section, preferably with at least 12 lateral surfaces. A polygonal core body is, on the one hand, more stable, and in particular, stiffer, than the cylindrical core bodies of known hydropower machines. Overall, a larger length-to-diameter ratio is possible. Furthermore, it is simpler and more cost-effective to manufacture such a polygonal core body. The cross-section of the core body is, in particular, a polygon that approximates a circle. 12 lateral surfaces have proven to be a good compromise between manufacturing effort and stability. The lateral surfaces can, for example, be aligned perpendicular to a connecting line with a common center point. The center point lies, in particular, on a rotational axis of the water wheel.

[0015] A polygonal core body of the waterwheel is advantageous regardless of the dimensions of the first buoyancy body and the spacer of the hydropower machine. Even with essentially floating hydropower machines, a polygonal core body can achieve advantages in terms of stability and manufacturing costs, for example. For an essentially floating hydropower machine, a spacer may not be necessary.

[0016] It is also extremely advantageous if the core body is produced by bending, in particular folding, one or more metal sheets. This is a particularly efficient production method for the core body, in particular because no machining of the material is necessary. Sheets are laser cut, for example, and folded into a polygon. The core body can, for example, be divided lengthwise and consist in particular of at least two parts. With a larger cross-section, several parts are also conceivable. The parts can be connected to one another in a form-fitting manner, for example by means of tabs, and / or in a force-fitting manner, for example by screws or rivets. The core body is preferably made of aluminum. However, other materials such as steel or plastic are also conceivable.

[0017] It is also advantageous if the hydropower machine comprises a second buoyancy body, which is preferably arranged at an inlet of the water wheel. This prevents twisting and submersion of the parts located in front of the water wheel due to torque when the hydropower machine is in the floating state. If the hydropower machine comprises a first and a second buoyancy body, the first buoyancy body, the second buoyancy body and the spacer must be dimensioned such that the hydropower machine rests on the bottom of the body of water at an average water level at the location where the hydropower machine is arranged during intended use, and is floatable at a water level above the average water level. The second buoyancy body is in particular positioned and dimensioned such that the water level is slightly below the lower edge of the second buoyancy body during normal operation.

[0018] It is also advantageous if the blades of the water wheel are trapezoidal. Straight blades aligned perpendicular to the direction of flow have the disadvantage that they have to be thicker in order to absorb the surface loads that occur during operation without permanent deformation. Furthermore, the simultaneous immersion of the entire width of the blade in the water leads to unfavorable fluctuations in the generated torque and pounding noises. The trapezoidal blade, for example, is curved in such a way that three surfaces are created which, when viewed from above, form a trapezoid. In this case, two surfaces of equal size converge at the same angle towards a smaller surface located in the center. The central surface, for example, runs radially to the core body of the water wheel. When the water wheel rotates, one edge of the central surface, for example, breaks through the water surface first.

[0019] It is advantageous if the blades of the water wheel have at least one radial bending edge. Bending edges increase the rigidity of the blades and allow for a thinner design, resulting in material and weight savings. Radial bending edges can be located between the blade surfaces already described. Additional bending edges can also be located in an outer region of the blades, where the blades have attachment areas for attachment to the water wheel.

[0020] It is also advantageous if the water wheel blades have at least one axial bending edge. Axial bending edges can also improve the rigidity of the blades. An axial bending edge can be located, for example, on the central surface of the blade described above.

[0021] It is particularly advantageous if the water wheel blades have one or more tabs for a positive connection to the core body. This allows the blades and core body to be easily connected. The tab can be located on the previously described central surface of the blade and connected to it via an axial bending edge. The core body can have corresponding openings to accommodate the tabs.

[0022] It is also advantageous if the water wheel has a first side disc, a second side disc, and at least one intermediate disc, with a plurality of blades arranged both between the first side disc and the intermediate disc and between the second side disc and the intermediate disc. The side discs can serve to stabilize the blades. The blades can be connected to the side discs by means of fastening areas. The side discs can, for example, cover the end faces of the core body. The core body, the blades, the side discs, and the intermediate disc can, for example, be made of the same material.

[0023] It is particularly advantageous if the first buoyancy body and / or the second buoyancy body are filled with a material that has a lower density than water, are filled with one or more hollow bodies, and / or are airtight. This provides the necessary buoyancy for the water wheel to float. The buoyancy bodies can be filled, for example, with a water-repellent foam. Alternatively or additionally, the buoyancy bodies can be filled, for example, with hollow plastic bodies.

[0024] Furthermore, it is advantageous if the waterwheel and the energy converter are connected via a multi-stage gear transmission. The naturally very low speed of the rotor is increased by using a transmission, allowing energy converters such as power generators, pumps, or other devices for harnessing the energy to be dimensioned more effectively. A multi-stage transmission can reduce the load on each individual stage. Energy losses between the stages can also be reduced. A stage, for example, is the interaction between two gears. The transmission can, for example, be two-stage, in particular with a gear ring on the waterwheel, an intermediate gear, and a pinion on the energy converter.

[0025] It is also advantageous if the gear train has several gears made of plastic, particularly using a 3D printing or injection molding process. Conventional gear trains have steel gears that must be protected from moisture and are therefore usually housed in a housing. These gear trains require oil lubrication for operation. To prevent potential environmental damage from leaking oil, the gear trains are therefore usually housed in a housing with a collecting basin. By using plastic gear trains, the hydropower machine according to the invention can dispense with both oil lubrication and separate housing. The gear train can be attached directly to the hydropower machine.

[0026] Depending on the required quantity, gear rims and gearwheels can be manufactured using either 3D printing or injection molding. For larger hydropower machines, it is advantageous to construct at least the gear rim in multiple segments. If a gear rim is mounted directly on the waterwheel, this allows for the replacement of defective gear rim segments without dismantling the entire waterwheel.

[0027] It is also advantageous for the hydropower machine to comprise at least two water wheels arranged side by side, which are connected by a common gear mechanism. This tandem design of the hydropower machine allows for a wider design and thus a greater coverage of the water body by the hydropower machine. The use of a common gear mechanism eliminates the additional components of another gear mechanism. In this case, the hydropower machine comprises, for example, two separately mounted and unconnected core bodies. An intermediate gear of the gear mechanism can be wider than before in order to absorb the rotational energy of both water wheels. The torque transmission of the core bodies can be coupled via the common intermediate gear mechanism. Gear rings of the gear mechanism can be arranged on the sides of the water wheels where they are adjacent, i.e. centrally in relation to the entire hydropower machine.

[0028] In this design, the second buoyancy body can be continuous across the entire width of the hydropower machine and offer greater stability against deflection. The hydropower machine can have additional spacers, particularly with additional support points for the bottom of the body of water. An additional support point can, for example, be located centrally on the hydropower machine between the water wheels. This design is particularly suitable for shallow and wide flowing waters.

[0029] In all designs, the hydroelectric machine can be anchored using flexible parts, such as ropes, or rigid parts. These are designed so that the hydroelectric machine can adapt to different water levels and floats at higher water levels, but is not drifted away by the current. Anchoring points on the bank must be installed high enough so that they are above the attachment points of the hydroelectric machine's components, even during floods. This ensures that the machine can adapt to the water level in all circumstances, and the anchoring prevents the hydroelectric machine from being forced below the water surface.

[0030] In the method according to the invention for operating a hydropower machine comprising a water wheel, at least one first spacer, a first buoyancy body, and an energy converter, a location of the hydropower machine in a body of water is first identified. Subsequently, an average water level at the location is determined, and the first buoyancy body and the spacer are dimensioned such that the hydropower machine rests on the bottom of the body of water at the average water level at the location and floats at a water level above the average water level.

[0031] As already described in detail, this allows not only the kinetic energy of a body of water to be used, but also the potential energy. When the water level is high, the hydroelectric machine is not flooded, but floats on the water surface. When the hydroelectric machine is in floating operation, the kinetic energy of the water body can still be used. The buoyancy also ensures that possible sediment deposits are eroded, particularly during floods, and that flotsam can pass through the hydroelectric machine. The hydroelectric machine does not pose a significant obstacle for fish either, as they can pass through the hydroelectric machine on at least one side in all operating modes. The hydroelectric machine can also specifically influence the water level in the inlet of the hydroelectric machine by deliberately blocking the water wheel.

[0032] The average water level can be determined as described above. In particular, the average water level for locations in Germany can be obtained from the data provided by the Federal / State Working Group on Water. Water level measurements can also be carried out by the user and / or manufacturer of the hydropower machine themselves. The first buoyancy body is dimensioned, for example, by adjusting its volume. The spacer is dimensioned, for example, by adjusting the height of the spacer or by adjusting the distance between a water wheel bearing and a lower edge of the spacer, which rests on the bottom of the body of water when the hydropower machine is used as intended.

[0033] In order to optimise energy conversion by the hydropower machine, obstacles can be provided in the water body to the side of the hydropower machine, which direct the flow preferentially towards the water wheel or which obstruct the free flow and thus direct more water through the hydropower machine.

[0034] The invention also provides for the use of a hydropower machine, in particular a hydropower machine according to the preceding description, at a location in a body of water with a defined mean water level, wherein a first buoyancy body and a spacer of the hydropower machine are dimensioned such that the hydropower machine rests on the bottom of the body of water at the mean water level at the location of use and floats at a water level above the mean water level. The previously described physical features of the hydropower machine can be implemented individually or in any combination. This results in the advantages already discussed in detail compared to exclusively floating uses of hydropower machines.

[0035] The hydropower machine according to the invention, as well as the method and use thereof, have the additional advantages of providing the greatest possible permeability for fish and other aquatic life, avoiding the deposits of suspended matter caused by dams, and allowing the use of environmentally friendly and easily recyclable materials. For example, the hydropower machine can be made of aluminum with over 90% of its weight, making it largely pure and recyclable with almost no sorting. The development of new recycling processes, such as those required for the disposal of wind turbine rotor blades, is completely eliminated with the invention presented here.

[0036] Furthermore, the hydroelectric machine can be used even at low flow velocities and does not require complex and therefore expensive redesign of the surrounding area by damming the water. It allows the use of hydropower in places where dams are not possible for geological reasons (e.g., earthquake zones). It also allows the influence of the discharge behavior of the watercourse during low and high water levels (to a limited extent).

[0037] In addition to pure electricity generation, the hydroelectric machine can also be used for pond aeration, for example. For this purpose, it is installed in the outlet of a fish pond. Using an air compressor, compressed air is generated and blown into the pond at one or more points.

[0038] Further advantages of the invention are described in the following exemplary embodiments. They show, schematically: Figure 1A hydropower machine according to the invention in an isometric view, Figure 2a water wheel of the hydropower machine in the view from Figure 1 , Figure 3 a blade of a water wheel of the hydropower machine, Figure 4 a first embodiment of a gear of the hydropower machine, Figure 5 a tandem design of the hydropower machine in an isometric view, Figure 6 an enlarged view of the gear from Figure 5 , Figure 7 the hydropower machine at the place of use at medium water level in a side view, Figure 8 the hydropower machine at the place of use during flooding, Figure 9 a power characteristic curve of the hydropower machine, and Figure 10 the hydropower machine at the place of use in a schematic plan view.

[0039] In the following description of the figures, identical reference numerals are used for identical and / or at least comparable features in the various figures. The individual features, their design, and / or mode of operation are usually only explained in detail when first mentioned. If individual features are not explained in detail again, their design and / or mode of operation correspond to the design and mode of operation of the features with the same or identical functions already described.

[0040] Figure 1 shows a hydropower machine 1 according to the invention in an isometric view. The hydropower machine 1 comprises a water wheel 2, wherein the water wheel 2 comprises a core body 3 and a plurality of blades 4. In addition, the hydropower machine 1 has a spacer 5, which ensures a minimum distance between the water wheel 2 and a bottom 6 of a body of water 7 at a location 8 of the hydropower machine 1 (see Fig. 7 ). The hydropower machine 1 also includes an energy converter 9 for processing the rotational energy of the water wheel 2. In this example, the energy converter 9 is designed as a generator.

[0041] The core body 3 of the water wheel 2 comprises a first buoyancy body 10. If the core body 3 of the water wheel 2 is designed to be airtight, for example, the core body 3 itself can serve as the first buoyancy body 10. The first buoyancy body 10 and the spacer 5 are dimensioned such that the hydropower machine 1 at an average water level MW (see Figure 7) at the location 8 where the hydropower machine 1 is located during intended use, rests on the bottom 6 of the body of water 7 and is floatable at a water level above the mean water level MW. In the present example, the hydropower machine 1 has two spacers 5 arranged to the side of the water wheel 2. These rest on the bottom 6 of the body of water 7 at the mean water level MW, with the movable / rotating part of the hydropower machine 1 being at a distance from the body of water bed 6 so that the mobility of the movable part is guaranteed even at low water levels. Essential for these properties is the distance 11 between a support edge 12 or support surface of the spacers 5 and a bearing 13 of the water wheel 2.According to the invention, a distance between the water wheel 2 and the water bed 6 is kept as small as possible in order to keep evasive currents below the water wheel 2 as small as possible and thus to better utilize the energy available in the water body 7.

[0042] A second buoyancy body 15 is arranged on an inlet side 14 of the hydroelectric machine 1. When the water level rises, this absorbs the torque generated by the water wheel 2 and is intended to prevent the hydroelectric machine 1 from twisting toward the riverbed 6. The second buoyancy body 15 at the inlet 14 can also be designed to improve the inflow angle to the blades 4. This improves the flow conditions and thus the energy yield, while simultaneously reducing the tensile force component in any anchoring 16, which can be implemented, for example, with cables. The energy converter 9 is arranged, for example, on the second buoyancy body 15.

[0043] Figure 2 shows the water wheel 2 of the hydropower machine 1 in the isometric representation of Figure 1The water wheel 2 and in particular the core body 3 are designed similarly to the self-supporting body commonly used in automobile construction. In the present exemplary embodiments, the core body 3 consists in cross-section of a polygon with at least 12 outer surfaces 17 and is preferably made of sheet metal, thus possessing a very high section modulus against torsion and bending. This allows it to be made thin and from a lightweight material such as aluminum. The interior of this core body 3 contains a buoyancy-generating material, for example a rigid foam. As already described, an alternative embodiment of the core body 3 is also conceivable, the water displacement of which generates the buoyancy. As a further alternative, it is also possible to equip the interior with shaped, airtight, slightly water-pressure-stable hollow bodies (for example, blow-molded plastic parts).

[0044] Since the largest part of the required lift volume is integrated into this construction, no additional lateral floats are required. The bearing 13 of the water wheel 2 can therefore also be made smaller and therefore lighter. The blades 4 are located on the lateral surfaces 17 of the polygon. The blades 4 are attached to the lateral surfaces 17 of the core body 3 as well as to an intermediate disk 18 and a first side disk 19a and a second side disk 19b. The attachment of the blades 4 to the polygon supports them with regard to the surface load occurring during operation and thus reduces the required sheet thickness of the blades 4. The attachment to the core body 3 can, for example, be via tabs 20 on the blades 4 (see Fig. 3) and corresponding openings 21 on the core body 3. Alternatively, the blades 4 can be secured with force-fitting screws or rivets. A gear ring 22 for a gear transmission 23 is provided on at least the first side disc 19a.

[0045] Figure 3shows a single blade 4 of the hydropower machine 1. The blade 4 is trapezoidal in shape, with several surfaces 24 separated from one another by radial bending edges 25a. Two outer surfaces 24 converge at the same angle to a centrally arranged surface 24. The middle surface 24 is connected via an axial bending edge 25b to a tab 20, which, as already described, serves for attachment to the core body 3. Via two further radial bending edges 25a, the outer surfaces 24 are connected to attachment areas 26, which serve to attach the blade 4 to the side disks 19a,b and the intermediate disk 18. Due to the trapezoidal design of the blade 4, the edges of the blade 4 do not dip into the water simultaneously when the water wheel 2 rotates. The bending edges 25 ensure increased rigidity of the blade 4.

[0046] Figure 4shows a transmission of the hydropower machine 1, which connects the waterwheel 2 to the energy converter 9. In this example, the transmission is designed as a multi-stage gear transmission 23 with several gears 27. Through the previously described gear ring 22, the first side disc 19a of the waterwheel 2 forms a gear 27 of the transmission. The waterwheel 2 is connected to a pinion of the energy converter via an intermediate gear. The gears 27 and the gear ring 22 can be made of plastic, for example.

[0047] Figure 5shows a tandem design of the hydropower machine 1, wherein two water wheels 2 are arranged side by side and connected by a common gear transmission 23. The second buoyancy body 15 is, for example, designed as a continuous unit and extends across the entire width of the hydropower machine 1. This design is particularly suitable for wide and shallow bodies of water 7. The shared transmission eliminates the need for additional components and the associated costs.

[0048] Figure 6 shows an enlarged section of the gear transmission 23 of the tandem device from Figure 7 Here, each side disc 19 of the water wheels 2 is provided with a gear ring 22. The intermediate gear and the pinion of the energy converter 9 are each wider than before in order to absorb the torque of both water wheels 2.

[0049] Figures 7 and 8show the hydropower machine 1 at its location 8 in a body of water 7 in a schematic side view. The body of water 7 is, for example, a river, the direction of flow of which is indicated by an arrow. In the example of the Figure 7 The hydropower machine 1 rests on the bottom 6 of the body of water 7. The water level corresponds to the average water level MW at this location 8. This corresponds, for example, to the definition of the Federal / State Working Group on Water.

[0050] The water level in front of the water wheel 2 results from a damming effect of the hydropower machine 1. The water level shown, for example, results from the maximum power 28 of the hydropower machine 1 (see Fig. 9 ) when the energy converter 9 is switched on and the flow resistance of the water wheel 2 is thus increased. The usable potential energy can be derived from the difference in the water level before and after the hydropower machine 1.

[0051] The hydroelectric machine 1 is dimensioned so that, at MW, it rests on the riverbed 6 with the spacers 5, and the water level in front of the waterwheel 2 is slightly below the lower edge of the second buoyancy body 15 at the inlet 14. This reduces undesirable water flow below the waterwheel 2. The design adapts the weight and buoyancy forces to the local operating conditions so that the water volumes, which fluctuate throughout the year, can be used as optimally as possible. The water level at the outlet of the waterwheel changes slightly when the energy converter 9 is switched on, depending on the shape of the water cross-section in the direction of flow after the waterwheel 2.

[0052] In extremely low water conditions, there is a risk that the water level may no longer be deep enough for fish and possibly other aquatic life. By deliberately slowing or stopping water wheel 2, the water level in front of water wheel 2 rises due to the reduced flow, forming a slightly deeper reservoir that can enable fish to survive until the next rainfall.

[0053] Figure 8shows the case when the water level rises, for example after rainfall, whereby the hydroelectric machine 1 lifts off the waterbed 6 and floats up, in accordance with the buoyancy forces of the first and second buoyancy bodies 10, 15. The water can therefore also flow beneath the waterwheel 2, resulting in a smaller level difference between the inlet 14 and outlet. The possible energy gain from potential energy is therefore lower than with the waterwheel 2 resting on the water. Depending on the cross-section of the waterway before, next to, and after the waterwheel 2, however, the flow velocity of the waterbody 7 can increase and thus increase the usable kinetic energy instead of the potential energy. The ratio of the buoyancy forces to the weight of the hydroelectric machine 1 determines up to what reservoir height the device will still rest on the water and at what point it will float up from the support edges 12.

[0054] Figure 9shows a schematic performance curve of hydropower machine 1. The load resistance through energy converter 9 is plotted on the abscissa axis. The power of hydropower machine 1 is plotted on the ordinate axis. In normal operation, waterwheel 2 is operated as close as possible to the maximum power point 28 (= maximum power point, MPP). This results from an optimal water level difference before and after hydropower machine 1 and thus optimal utilization of the potential energy. To the left of the maximum power point 28, hydropower machine 1 is in throughflow mode 29, and to the right of the maximum power point 28, it is in damming mode 30.

[0055] The damming operation 30 is characterized by an increase in the load resistance beyond the maximum power 28, which increases the flow resistance and raises the water level in front of the hydropower machine 1. This can be used to regulate the water level.

[0056] Figure 10 shows a schematic plan view of the position of the hydropower machine 1 in a flowing water body 7. It is attached to the bank via two anchoring points 16. The distance between these two points 16 is greater than the width of the hydropower machine 1, thus preventing lateral movement ("swaying").

[0057] A usable width 31 and a passage width 32 must be defined individually for the respective intended location of the hydropower machine 1. Their relationship to one another depends essentially on the size of the flowing water 7 and its use, for example by watercraft such as boats or canoes. The usable width 31 defines the usable volume flow 33 and the passage width 32 the freely flowing volume flow 34. Both are indicated by corresponding arrows. For smaller flowing waters 7 not used by watercraft, the passage width 32 is dimensioned similarly to a fish ladder. A suitable design of this area should enable fish to pass through even at low tide, indicated in the illustration by the freely flowing volume flow 34.

[0058] For larger waterways 7, the passage width 32 is adjusted to the type and size of the watercraft (canoes, boats, ships) and limits the usable width 31 available for the waterwheel 2. A fish ladder design is not necessary due to the significantly greater water depth. Of the total volume flow of a waterway 7, only the usable volume flow 33 is used for energy generation. The process described here is referred to as "partial flow utilization of waterways."

[0059] At low water levels, hydropower machine 1 is operated in damming mode 30 (see Figure 9); the power generated is lower than when operating at the MPP, and the increased flow resistance raises the water level. This provides aquatic life, primarily fish, with a place to survive during low water periods when they would otherwise die. In the event of heavy rain, the hydropower machine 1 can initially be switched to throughflow mode 29 to lower the water level. When the water surge arrives, the system is switched to impoundment mode 30 so that the flood wave is delayed and passed on in a dampened manner only after the buffer volume has been filled. List of reference symbols

[0060] 1Hydropower machine 2Waterwheel 3Core body 4Blades 5Spacer 6Ground / waterbed 7Waterbody 8Location 9Energy converter 10First buoyancy body 11Distance 12Support edge 13Bearing 14Inlet side / inlet 15Second buoyancy body 16Anchoring point / anchoring 17Shell surface 18Intermediate disc 19 a) First side disc b) Second side disc 20Tab 21Opening 22Gear ring 23Gear drive 24Surface 25 a) Radial bending edge b) Axial bending edge 26Fastening area 27Gear 28Maximum power 29Through operation 30Impounding operation 31Useful width 32Passage width 33Useful volume flow 34Freely flowing volume flow MWaverage water level

Claims

1. Hydropower machine (1) with - a water wheel (2), wherein the water wheel (2) comprises a core body (3) and a plurality of blades (4), - at least one spacer (5) which defines a minimum distance between the water wheel (2) and a bottom (6) of a body of water (7) at a location (8) of use of the hydropower machine (1), and - an energy converter (9) for processing the rotational energy of the water wheel (2) characterized by that the core body (3) of the water wheel (2) comprises a first buoyancy body (10), wherein the first buoyancy body (10) and the spacer (5) are dimensioned such that the hydropower machine (1) rests on the bottom (6) of the body of water (7) at an average water level (MW) at the location (8) at which the hydropower machine (1) is arranged during intended use, and is buoyant at a water level above the average water level (MW).

2. Hydropower machine (1) according to the preceding claim, characterized in that the core body (3) has a polygonal cross-section, preferably with at least 12 lateral surfaces (17).

3. Hydropower machine (1) according to the preceding claim, characterized in that the core body (3) is produced by bending, in particular folding, one or more sheets.

4. Hydropower machine (1) according to one of the preceding claims, characterized by a second buoyancy body (15), which is preferably arranged at an inlet (14) of the water wheel (2).

5. Hydropower machine (1) according to one of the preceding claims, characterized in that the blades (4) of the water wheel (2) are trapezoidal.

6. Hydropower machine (1) according to one of the preceding claims, characterized in that the blades (4) of the water wheel (2) have at least one radial bending edge (25a).

7. Hydropower machine (1) according to one of the preceding claims, characterized in that the blades (4) of the water wheel (2) have at least one axial bending edge (25b).

8. Hydropower machine (1) according to one of the preceding claims, characterized in that the blades (4) of the water wheel (2) have at least one tab (20) for positive connection to the core body (3).

9. Hydropower machine (1) according to one of the preceding claims, characterized in that the water wheel (2) has a first side disc (19a), a second side disc (19b) and at least one intermediate disc (18), wherein a plurality of blades (4) are arranged both between the first side disc (19) and the intermediate disc (18) and between the second side disc (19) and the intermediate disc (18).

10. Hydropower machine (1) according to one of the preceding claims, characterized in thatthe first buoyancy body (10) and / or the second buoyancy body (15) is filled with a material which has a lower density than water, is filled with one or more hollow bodies and / or is airtight.

11. Hydropower machine (1) according to one of the preceding claims, characterized in that the water wheel (2) and the energy converter (9) are connected to each other via a multi-stage gear transmission (23).

12. Hydropower machine (1) according to the preceding claim, characterized in that the gear transmission (23) has a plurality of gears (27) which are made of plastic, in particular in a 3D printing or injection molding process.

13. Hydropower machine (1) according to one of the preceding claims, characterized by at least two water wheels (2) arranged next to one another, which are connected to a common gear (23, 28).

14. Method for operating a hydropower machine (1) which comprises a water wheel (2), at least one first spacer (5), a first buoyancy body (10) and an energy converter (9), wherein - a location (8) of the hydropower machine (1) in a body of water (7) is identified, - an average water level (MW) at the location (8) is determined, and - the first buoyancy body (10) and the spacer (5) are dimensioned such that the hydropower machine (1) rests on the bottom (6) of the body of water (7) at the average water level (MW) at the location (8) and floats at a water level above the average water level (MW).

15. Use of a hydropower machine (1), in particular a hydropower machine (1) according to one or more of the preceding claims, at a location (8) in a body of water (7) with a defined mean water level (MW), wherein a first buoyancy body (10) and a spacer (5) of the hydropower machine (1) are dimensioned such that the hydropower machine (1) rests on the bottom (6) of the body of water (7) at the mean water level (MW) at the location (8) and floats at a water level above the mean water level (MW).

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