DE20007642U1 - Floating bucket wheel aerator, rotary drive for this as well as pivot bearing, housing ventilation and bucket wheel - Google Patents

Description

Floating paddle wheel aerator. Rotary drive for this and rotary bearing. Housing ventilation and paddle wheel

The innovation relates to a floating paddle wheel aerator for aerating water and sewage treatment tanks, with a frame, floats connected to the frame, a shaft mounted on parts of the frame and connected to a rotary drive, and blades mounted on the shaft, of which the floats float on the surface of the water or sewage treatment tank when the aerator is in operation, the shaft rotates above the water or sewage treatment tank level and parts of the rotating blades reach below this level; as well as a rotary drive in the form of an electric motor with a housing, a suitable rotary bearing with an inner ring and an outer ring for swinging the shaft and housing vents with an air hole in the housing for the passage of air, which are suitable for such paddle wheel aerators or other devices located in the splash water area. The innovation also relates to a paddle wheel for a floating paddle wheel aerator, the paddle wheel having blades arranged in a star shape.

The paddle wheel aerators are used to stir up the water surface, for example in marine fish, crab and mussel farms or other aquatic cultures, but also in sewage treatment tanks, with the help of paddles that hit the water. The aerator floats back and forth over the surface of the body of water to be aerated according to a plan, or is anchored in a stationary location.

Known models of such paddle wheel aerators have three parallel floats that are bridged by a frame. The frame carries a mostly electric drive motor with a gear above the central float, which in the known paddle wheel aerators is a worm gear and reduces the speed considerably, and from this gear shafts run on both sides in the direction of the edge floats, which carry parallel rings of paddle wheels arranged in a star shape in radial planes. In order to enable certain mutual movements of the floats, the shafts on both sides, which are each mounted on the edge float with the help of a hydrostatic bearing, are connected to the output shafts of the gearbox via cardan joints or Hardy disks.

These well-known paddle wheel aerators have a relatively complex structure and are themselves relatively short-lived due to the short lifespan of some of their components. In particular, the gear in the gear box and the shaft suspensions including the hydrostatic bearings, which are plastic bearings with water sliding surfaces, have a short service life. The function of the motor and gear in particular is impaired by water penetrating and remaining in the housing, especially sea water. Parts of the spun water penetrate both through the bearings and through the air holes that are intended to allow the interior of the housing to breathe, and lead to accelerated corrosion. Due to its design, the worm gear has a relatively shorter service life due to higher friction of the moving parts and a lower efficiency than other gears such as spur gears.

The innovation is intended to avoid these disadvantages and, in particular, to increase the useful life of the device. This is achieved through various measures that improve the situation individually or in combination and some of which are also suitable and used for other applications.

The innovative floating jschau1teli«adb'eTu.fter is characterized by,

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that the shaft is mounted on the frame via rotary bearings with a degree of freedom of pivoting of the shaft relative to the frame within a given solid angle, and/or in that the rotary drive is located at one end of the shaft and has a torque support against the frame, or in that the rotary drive is located at one end of the shaft and is arranged together with the gear, in particular a spur gear, in a housing with a spherical outer surface, which in turn is mounted in a counter bearing with a corresponding spherical recess on the frame, in particular a float, so that its position can be changed. The rotary drive can be a motor, preferably an electronically controlled electric motor with a control unit which is encapsulated on the inside of the motor housing, and in particular a brushless slow-running disk rotor motor with a permanent magnet rotor which drives the shaft directly due to its low speed.

The solid angle can, for example, have an intersection angle of 10°. This allows for distortions within the frame due to waves as well as discrepancies between the shaft bearings in terms of axial direction and angle due to manufacturing tolerances or due to later harsh operating conditions.

Various designs are possible for the degree of freedom of the pivot bearings, but it is preferred that the pivot bearings each have an outer ring that can be rotated relative to the frame within the given solid angle, for example due to a ball bearing-like holder. For example, the outer ring can have an outer surface in the form of a right circular cylinder onto which a ball zone ring is mounted, or the outer ring itself can have a ball zone outer surface that can be rotated in a ball inner surface of a bearing block. However, the use of an elastic intermediate ring is also possible. This design with an outer ring that cannot be pivoted relative to the shaft has the advantage of making it easier to seal the pivot bearing against the rotating shaft, as the sealing ring that rests on the shaft sits on parts connected to the outer ring of the pivot bearing that cannot be pivoted relative to the shaft. Otherwise, the sealing rings must be made of a material with very high compressibility in order to maintain the sealing effect in the event of pivoting.

The pivot bearing on the side of the motor can be equipped in a conventional manner if the motor as a whole is arranged rotatably on the frame together with, for example, a spherical housing.

The preferred configuration is that the shaft is supported by one of these pivot bearings at each end and carries the blades between its bearings, in particular with two floats on which the frame sits in the area of one of the supported ends of the shaft. This results in a relatively light, robust, torsion-resistant and durable construction.

The bearings are preferably supplemented by a water removal installation for axial and radial water removal from a housing surrounding the rotary bearing, firmly connected to a frame with at least one ring disk directed towards the shaft, concentrically surrounding it, which is arranged between or adjacent to rotating ring elements sitting on the shaft, namely centrifugal disks and/or axial conveyors, leaving a gap between them. With these measures, water accumulation in the area of the bearings can be prevented in the case of paddle wheel aerators and other devices that work in the water spray area.

The service life of paddle wheel fans and other devices in the splash water area is also limited by water that penetrates through the air hole in the motor and gear housing. Due to temperature changes, however, an exchange of air with the outside air is necessary in these housings. The penetration of water through the air holes is now prevented by an expansion vessel of variable volume that is closed to the outside and is connected to the air hole on the outside of the housing. The expansion vessel can be a flexible bellows or an expandable balloon, for example, and can also be connected to the air hole via a long air line in order to be able to arrange such sensitive parts in a protected location.

Further details, advantages and developments of the innovation emerge from the following description of a preferred embodiment with reference to the drawing. They show:

Fig. 1 A perspective view of a paddle wheel aerator according to the invention;

Fig. 2 is a perspective view of a paddle wheel aerator modified in detail, seen from the other side;

Fig. 3 is a schematic side view of a paddle wheel shaft of the paddle wheel aerator in a slightly bent state, and its bearings;

Fig. 4 shows a section through an embodiment of a ball bearing mounted rolling bearing;

Fig. 5 is a section through an embodiment of an elastically suspended rolling bearing;

Fig. 6 shows a section through a shaft bearing which can be used in a paddle wheel aerator with measures for expelling water;

7-9 Partial sections of a detail corresponding to Fig. 6, each of a modified design;

Fig. 10 is a section through a further embodiment of a shaft bearing usable in a paddle wheel aerator with a further embodiment of measures for expelling water;

Fig. 11 is a schematic section through a slow-speed motor which can be used in a paddle wheel aerator;

Fig. 12 is a partially sectioned side view of an engine with closed ventilation;

Fig. 13 is an end view of a motor with closed ventilation according to a modified embodiment;

Fig. 14 is a schematic, perspective side view and top view of a motor together with a gearbox within a common housing which is mounted on a float, as well as a perspective view of the housing bearing;

Fig. 15 is a perspective view of a paddle wheel with star-shaped blades;

Fig. 16 is a perspective view of a float with a device for arranging a counterweight.

A paddle wheel aerator according to Fig. 1 and 2 has a more or less rigid, defining a horizontal plane parallel to the water surface.

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Frame 1, which in the illustrated embodiment consists of two profile bars 2 and two floats 3, which together form approximately a rectangle. The distance between the two floats, which are opposite each other as rectangular sides, is bridged, with the floats in a central position and parallel to the profile bars 2, by a paddle wheel shaft 4, which in the form of four parallel paddle wheels carries blades 5 arranged in a star shape, which, when the paddle wheel aerator is in operation, reach below the water level as they rotate and keep the water moving and ventilate it by stirring and spraying it.

The shaft 4 is driven by an electric motor 10, which may be connected to a gearbox, at a speed preferably in the order of between 100 and 180 revolutions per minute. For this purpose, the floating paddle wheel aerator hangs from a cable pulled through or over the water. The electric motor 10 sits on the end of the shaft 4 and has a torque support with a lot of play in relation to the frame 1. Such an electric motor 10 can, if necessary, be supported only by the shaft. In Fig. 1, the electric motor is not visible because it is covered by a protective housing 11. In Fig. 2, however, it is visible in the form of its motor housing 12. The torque support can also be seen there, consisting of a vane 13 which is rigidly connected to the motor housing 12 on the one hand and which lies at a certain distance between two rubber blocks 14 which are seated on flanges 15 which are rigidly connected to the frame 1. According to a simplified embodiment, the wing 13 is supported against the frame 1 in the manner described only in one direction of rotation, namely in the direction of rotation opposite to the drive direction.

The shaft 4 is supported in the area of its two ends on parts of the frame, namely with bearings 20 and 21, of which, for example, the bearing 21 closer to the motor 11 can be a fixed bearing and the bearing 20 facing away from the motor 10 can be a floating bearing. The use of two floating bearings and an axial fixation of the shaft in some other way could also be considered, or the use of two fixed bearings, one of which sits in a bearing block with a certain axial degree of freedom.

These bearings 20, 21 each have an inner ring and an outer ring. They are characterized

by the ability to twist or bend the axis of the shaft 4 relative to the frame 1 by a certain solid angle α (Fig. 3), which is, for example, 10°, so that the shaft 4 can be inclined by an amount of 5° with respect to the straight connection between the bearings. This allows the shaft to bend slightly, which prevents extreme bearing pressure from occurring when the frame is twisted, for example in the case of waves or due to manufacturing tolerances. The shaft 4 therefore does not contribute anything to stabilizing the shape of the frame 1, which avoids increased bearing pressure or the need for universal joints, etc. along the shaft. This is shown schematically in Fig. 3. Because one of the bearings is designed as a floating bearing, such bends do not create any significant tensile forces in the axial direction on the bearing.

The measures with regard to the possibility of rotation within the solid angle can basically be provided between the shaft 4 and the bearing 20, 21, within this bearing or between the bearing and a surrounding bearing block 22 fixed to the frame. The bearing block can also be integrated into one of the floats 3. However, for reasons of sealing the bearing area by means of sealing rings within which the shaft slides, it is preferred that the measures are provided between the bearing 20, 21 and the bearing block 22. Figs. 3 to 6 show examples of corresponding measures.

Each of the bearings has an outer bearing ring 23 and an inner bearing ring 24, between which balls 25 roll in the roller bearings shown. Instead of roller bearings, plain bearings can also be used in the same way. According to Fig. 4, the outer bearing ring 23 has a spherical outer surface 31, i.e. an annular spherical zone surface, which is opposite a corresponding inner surface 32 of the bearing block 22. The radii of curvature of the surfaces 31 and 32 are coordinated with one another in such a way that the surface 31 can slide within the surface 32, in the manner of a ball joint. The inner bearing ring 24 and thus the shaft 4 can also be pivoted like a ball joint with the outer bearing ring 23. The bearing 20 or 21 comprising the bearing rings 23 and 24 is initially installed transversely until it is erected in the cavity between the annular, curved inner surface 32.

Fig. 4 also illustrates measures for sealing the bearing 20. While it is sealed by a plate 33 on the side of the shaft end, a sealing ring arrangement 34 is firmly connected to the outer bearing ring 23 on the side facing the blades 5. Since the axes of the shaft 4 and the bearing ring 23 cannot pivot relative to one another, the sealing ring arrangement 34 can lie tightly and precisely on the shaft 4.

In cases where sealing of the bearing is not necessary at this point, or in cases where large-volume sealing rings with high compressibility are permissible, so that the shaft 4 and the sealing ring arrangement 34 do not always have to be coaxial with one another, the pivotability provided by the surfaces 31, 32 can also be created at another point, for example by a spherical zone ring surface on the shaft and an inner bearing ring arranged above it, in two parts for assembly reasons, with a corresponding concave inner surface. Another alternative with an outer bearing ring that can pivot against the shaft 4 is the well-known self-aligning ball bearing or a ball bearing with a spherical outer ring.

Fig. 5 shows a modified bearing arrangement in which the outer bearing ring 23 has a right circular cylindrical surface on the outside, but an elastic ring body 38 is inserted between the bearing ring 23 and the bearing block 22, the design of which is such that the pivoting of the shaft 4 is absorbed by the elastic deformability of this ring body 38.

In Fig. 6, the bearing 20 is again shown with the outer bearing ring 23 and the inner bearing ring 24, which is a commercially available ball bearing with a cylindrical outer bearing surface, as in Fig. 5. However, a ball zone ring body 40 is mounted on this, which has an outer surface on its outside that corresponds to the outer surface 31 of Fig. 4 and can slide on the inner surface 31 of the bearing block 22.

Of interest in the construction of Fig. 6 is an outer, approximately barrel-shaped bearing housing 44 with measures that serve the continuous drainage of the area of the bearing 20. For this purpose, the bearing housing 44 has a drainage channel 45 at the bottom, which

is open towards the inside of the housing 44. A collecting channel 46 is arranged in the housing 44, which runs inside around the circumference of the housing, outwards, i.e. towards the housing wall and all the way around, is open on the side facing away from the bearing, and closed towards the axis. In its lower, inverted configuration it also overflows the drainage channel 45 and drains into it. Close to the open edge of the channel 46 there is a centrifugal disk 47 which is mounted on the shaft 4 and rotates with it, and which is followed in the axial direction, facing away from the channel 46, by a separating ring disk 49 which projects inwards from the housing, leaving an annular gap 48 free. An annular gap 50 remains between the disk 49 and the shaft 4 for air to pass through, and in turn in the axial direction this disk 49 is followed by a fan wheel 51 which is mounted on the shaft 4. This arrangement means that air, which flows into the housing 44, for example through the channel 45 or through special ventilation openings, is constantly sucked out via a labyrinth-like arrangement in which the water that has penetrated is thrown off or runs off and reaches the drainage channel 45. This constant water drainage is particularly important in the case of seawater, which attacks metals more quickly.

In Fig. 7, parts 46 and 47 are shown in a modified form, namely with a cranked centrifugal disk 47; comparable to Fig. 8, where the centrifugal disk 47 is conical. Fig. 9 again shows the entire system of the parts used for water removal, but here the impeller 51 has been moved to the other side so that it presses the air enriched with water against the components 46, 47 and 49, where it is then drained.

Fig. 10 shows a further embodiment of a shaft bearing with a further embodiment of measures for expelling water. A rotary bearing 20, 21 is equipped with an inner ring 24 and an outer ring 23 for supporting the shaft 4, the inner ring consisting, for example, of a stainless steel bushing that wraps around the shaft and the outer ring 23 is equipped with a spherical outer surface that is mounted in a corresponding recess within the housing. To facilitate assembly and final assembly of this outer ring with its spherical outer surface, this spherical outer surface has a flattening at two opposite points. The rest of the outer surface is

spherical. This flattening of the spherical surface is shown in Fig. 10. Furthermore, a ball bearing 25 is arranged between the inner ring 24 and the outer ring 23. To seal the structure against the ingress of water, shaft seals 58, a circlip 59 and a V-ring 59a, for example made of rubber, are arranged for axial shaft sealing. The means for axially removing water consist of a housing 44, a centrifugal disk 52, a collecting channel 46 and an opening 54 within the housing in the lower part. Water which has penetrated into the device as far as the actual rotary bearing is thus thrown by the centrifugal disk, which is firmly connected to the shaft, onto the radial outer wall of the centrifugal disk and runs along this radial outer wall to the end of this outer wall, where it drips onto the collecting channel 46. The water then runs in a circular pattern along the outer surface of this collecting channel due to gravity up to the height of the shaft and is then drained along a web 55 attached to the collecting channel on the inside into the lower part of the collecting channel, where the water drips between the web 55 and the outer wall of the housing into the lower part of the housing and then escapes to the outside through an opening 54. The centrifugal disk 56 also has a protective effect against water that has penetrated into the space between the centrifugal disk and the housing, viewed in the direction of the impellers. This means that water that has penetrated into this space cannot even reach the actual rotary bearing. The centrifugal disk 52 also has a radially extending wall 56 that can be extended in a radial direction by means of a comb 57 that rests in a ring on a shoulder on this surface. This also prevents unwanted water flows on the outer wall of the centrifugal disk.

For example, the drive of shaft 4 is an electric motor with a gear that reduces the motor speed to the order of 120 revolutions per minute. Depending on the environmental conditions and the requirements of the device, however, other speeds are also conceivable, such as half or double the speed of 120 revolutions per minute. As an alternative to this, Fig. 11 shows a schematic of a slow-running disk rotor motor with electronic control. The disk rotor runs in a known manner between windings in which

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the current is controlled by an electronic control device 70. The motor housing 12 of the motor described is made of metal and the electronic control device 70 is embedded in the metal housing so that it is safely protected from splashing or seeping water. The control is integrated in the motor housing.

The housing 12 of the electric motor 10 and, if present, the gearbox housing require ventilation so that the thermally induced volume changes of the air in the housing can be compensated. An air hole 72 is used for this purpose, but to prevent water from entering, a closed expansion vessel is placed on top of this, which is a bellows 73 according to Fig. 12. According to Fig. 13, this is an expandable balloon 74, which is not located directly on the air hole 72, but is connected to it via an air line 75. The balloon 74 itself is housed in a small protective housing 76 attached to the underside of the motor housing 12, where it is protected against attacks by animals as well as against dangers from rough operating conditions. This design is also indicated in Fig. 2. If a motor housing and a gearbox housing are present, the two air holes can also be connected to a common expansion vessel via separate air lines.

Fig. 14 shows a side view and a top view of a motor together with a gear box within a common housing, this housing having a spherical outer surface. The spherical outer surface of the housing 16 is mounted in a recess 17a with a matching counter bearing 17b, which is attached to a float of the device. This makes it possible for the motor and the gear box to flexibly undergo pivoting of the shaft relative to the frame within a given solid angle α together with the housing without distortion. In a further embodiment, which is not shown in the figures, it is possible to arrange the motor together with the gear box between two shells which have spherical inner surfaces and accommodate the motor with a spherical outer surface. In contrast to the embodiment using a housing 16, this is an open version of the motor mounting.

Fig. 15 shows a more detailed view of a single impeller with star-shaped

arranged blades 5, which are fastened to the impeller disk by means of profile arms 6. Such profile arms 6 can, for example, be iron profiles with an L shape or, in a double arrangement, with a T shape, which are arranged and fastened on both sides of the disk by means of screws, extending radially. At the open end of two such parallel T-irons, a blade 5 is arranged by means of screw connections. By using screw connections as fastening means, as opposed to welds, it is possible for significantly greater forces to act on the blades without causing the fastenings between the blade and the profile arm and/or the profile arm and the impeller disk to loosen. The blades themselves can be equipped with or without openings. Two profile arms, each extending radially in parallel, can be connected at their free ends with screws, in that the gap between two profile arms is filled by deep-drawing the profile arm at this screw connection point.

Fig. 16 shows a float with a device 60 for arranging a balancing weight, whereby such a balancing weight can have a variable volume. Such a device is, for example, a vessel that is closed by means of a cover and a seal arranged between the cover and the rest of the vessel and can optionally be filled with various materials, such as sand, water and other materials. Such a balancing weight is to be arranged on the float opposite the float on which the motor is arranged, since otherwise a horizontal position of the entire device would not be guaranteed. Due to the inclusion of various materials, it is possible that the materials are only filled on site during assembly and thus do not have to be supplied in the unassembled state, for example until delivery.

The measures described, when applied to a paddle wheel aerator, work together to protect against premature wear and corrosion and therefore contribute to an increased service life of the device. They can be applied together or individually. Some of the measures are also useful on devices other than paddle wheel aerators, whereby the protection is also claimed independently of the application described as an example.

Claims (31)

1. Floating paddle wheel aerator for aerating water bodies and sewage treatment tanks, with a frame ( 1 ), floats ( 3 ) connected to the frame, a shaft ( 4 ) mounted on parts of the frame and connected to a rotary drive ( 10 ), and blades ( 5 ) seated on the shaft, of which the floats float on the surface of the water body or sewage treatment tank when the aerator is in operation, the shaft rotates above the water body or sewage treatment tank level, and parts of the co-rotating blades reach below this level, characterized in that the shaft ( 4 ) is mounted on the frame ( 1 ) via rotary bearings ( 20 , 21 ) with a degree of freedom of pivoting of the shaft relative to the frame within a given solid angle (α). 2. Paddle wheel aerator according to claim 1, characterized in that the rotary bearings ( 20 , 21 ) each have an outer ring ( 23 ) which is rotatable against the frame ( 1 ) within the given solid angle. 3. Paddle wheel aerator according to claim 2, characterized in that the outer rings ( 23 ) of the rotary bearings ( 20 , 21 ) are ball-bearing mounted in the frame ( 1 ). 4. Paddle wheel aerator according to claim 1, characterized in that the outer ring ( 23 ) and/or the inner ring ( 24 ) of the individual rotary bearing ( 20 , 21 ) is supported against the frame ( 1 ) or the shaft ( 4 ) via an elastic intermediate ring ( 38 ). 5. Paddle wheel aerator according to claim 1, characterized in that the shaft is ball-bearing mounted in the inner rings of the rotary bearings. 6. Paddle wheel aerator according to claim 1, characterized in that the rotary bearings are pendulum roller bearings. 7. Paddle wheel aerator according to one of claims 1 to 4, characterized in that sealing rings ( 34 ) of the rotary bearings ( 20 , 21 ) resting on the shaft ( 4 ) are seated on parts ( 23 ) of the rotary bearing which cannot be pivoted relative to the shaft. 8. Paddle wheel aerator according to one of claims 1 to 6, characterized in that the rotary bearings ( 20 , 21 ) have sealing rings made of a material of high compressibility. 9. Paddle wheel aerator according to one of claims 1 to 8, characterized in that the shaft ( 4 ) is mounted in the region of its ends with one of these rotary bearings ( 20 , 21 ) and carries the blades ( 5 ) between its bearings. 10. Paddle wheel aerator according to claim 9, characterized in that the frame ( 1 ) has an at least approximately rectangular basic configuration and comprises two floats ( 3 ) forming opposite rectangular sides, on each of which one of the mounted ends of the shaft ( 4 ) sits. 11. Paddle wheel aerator according to one of claims 1 to 10, characterized in that the shaft ( 4 ) is axially fixed at a maximum of one point ( 21 ) of its length. 12. Paddle wheel aerator for aerating water bodies and sewage treatment tanks, with a frame ( 1 ), floats ( 3 ) connected to the frame, a shaft ( 4 ) mounted on parts of the frame and connected to a rotary drive ( 10 ), and blades ( 5 ) seated on the shaft, of which the floats float on the water or sewage treatment tank surface when the aerator is in operation, the shaft rotates above the water or sewage treatment tank level, and parts of the co-rotating blades reach below this level, in particular according to one of claims 1 to 11, characterized in that the rotary drive ( 10 ) is seated on one of the shaft ends and has a torque support ( 13 , 14 , 15 ) against the frame ( 1 ). 13. Paddle wheel aerator according to claim 12, characterized in that the rotary drive ( 10 ) is an electric motor with a flanged gear housing containing a spur gear. 14. Paddle wheel aerator for aerating water bodies and sewage treatment tanks, with a frame ( 1 ), floats ( 3 ) connected to the frame, a shaft ( 4 ) mounted on parts of the frame and connected to a rotary drive ( 10 ), and blades ( 5 ) seated on the shaft, of which the floats float on the surface of the water body or sewage treatment tank when the aerator is in operation, the shaft rotates above the water body or sewage treatment tank level, and parts of the co-rotating blades reach below this level, in particular according to one of claims 1 to 11, characterized in that the rotary drive ( 10 ) is seated on one of the shaft ends and is arranged together with a gear inside a housing ( 16 ), the housing having a predominantly spherical outer surface. 15. Paddle wheel aerator according to claim 14, characterized in that the housing ( 16 ) of the rotary drive ( 10 ) is arranged in a recess ( 17a ) shaped to match the spherical outer surface of the housing, which is mounted on one of the floats ( 3 ), together with a matching counter bearing ( 17b ). 16. Rotary drive in the form of an electric motor ( 10 ) with a housing ( 12 ), for a floating paddle wheel aerator, in particular according to one of claims 1 to 12, characterized in that the rotary drive is an electronically controlled electric motor ( 10 ) with an electronic control device ( 70 ) which is encapsulated on the inside of the motor housing. 17. Rotary drive according to claim 16, characterized in that the electric motor ( 10 ) is a brushless slow-running disk rotor motor with a permanent magnet rotor ( 71 ). 18. Rotary drive according to claim 16 or 17, characterized in that the electric motor ( 10 ) is a brushless disk rotor motor without rotor position sensors. 19. Pivot bearing ( 20 , 21 ) with an inner ring ( 24 ) and an outer ring ( 23 ) for the pendulum mounting of a shaft ( 4 ), in particular for a floating paddle wheel aerator according to one of claims 1 to 15, characterized in that the outer ring ( 23 ) has an outer surface in the form of a right circular cylinder, onto which a ring ( 40 ) with the outer surface of a spherical zone containing a spherical diameter plane is mounted. 20. Pivot bearing ( 20 , 21 ) with an inner ring ( 24 ) and an outer ring ( 23 ) for the pendulum mounting of a shaft ( 4 ), in particular for a floating paddle wheel aerator according to one of claims 1 to 15, characterized in that the outer ring ( 23 ) has the outer surface of a spherical zone which contains a spherical diameter plane ( Fig. 4). 21. Pivot bearing ( 20 , 21 ) with an inner ring ( 24 ) and an outer ring ( 23 ) for the pendulum mounting of a shaft ( 4 ), in particular for a floating paddle wheel aerator according to one of claims 1 to 15, in particular according to claim 19 or 20, characterized in that it is supplemented by a water removal installation for axial water removal from a housing ( 44 ) surrounding the pivot bearing ( 20 ) and firmly connected to a frame ( 1 ) with at least one annular disk ( 49 ) directed against the shaft ( 4 ), concentrically surrounding it, which is arranged between or adjacent to rotating ring elements sitting on the shaft, namely centrifugal disks ( 47 ) and/or axial conveyors ( 51 ), leaving an intermediate gap ( 48 ). 22. Pivoting bearing ( 20 , 21 ) with an inner ring ( 24 ) and an outer ring ( 23 ) for the pendulum mounting of a shaft ( 4 ), in particular for a floating paddle wheel aerator according to one of claims 1 to 15, in particular according to claim 19 or 20, characterized in that it is supplemented by a water removal installation for axial water removal from a housing ( 44 ) surrounding the pivot bearing ( 20 ) and firmly connected to a frame ( 1 ), a centrifugal disk ( 52 ) arranged within the housing ( 44 ), which concentrically surrounds the shaft ( 4 ) and a collecting channel ( 46 ) arranged thereon, and an opening ( 54 ) arranged in the lower part of the housing ( 44 ) for the drainage of accumulated water. 23. Pivot bearing ( 20 , 21 ) according to claim 22, characterized in that the collecting channel ( 46 ) is arranged concentrically around a shaft and is designed such that in its upper half water flows off the outer surface of the collecting channel and in its lower half this water flows off an additionally attached web ( 55 ) in order to be transported away at the lowest part of this web ( 55 ) via the water drainage opening ( 54 ). 24. Pivot bearing ( 20 , 21 ) according to claim 22 or 23, characterized in that the centrifugal disk ( 52 ) terminates with a surface ( 56 ) extending radially away from the shaft and on this surface an annular ridge ( 57 ) is arranged which extends the radial extent of the surface ( 56 ). 25. Housing vents, in particular for motor and/or gear housings ( 12 ) of the rotary drive ( 10 ) of floating paddle wheel ventilators according to one of claims 1 to 15, with an air hole ( 72 ) located in the housing for the passage of air, characterized in that an expansion vessel ( 73 , 74 ) of variable volume, closed to the outside, is connected to the air hole ( 58 ) on the housing outside. 26. Housing vents according to claim 25, characterized in that the expansion vessel is a flexible bellows ( 73 ). 27. Housing vents according to claim 25, characterized in that the expansion vessel is an expandable balloon ( 74 ). 28. Housing ventilation according to one of claims 25 to 27, characterized in that the expansion vessel ( 73 , 74 ) is connected to the air hole ( 72 ) via an air line ( 75 ). 29. Paddle wheel with star-shaped blades ( 5 ) for arrangement on a shaft ( 4 ), in particular for a floating paddle wheel aerator according to one of claims 1 to 15, characterized in that the blades ( 5 ) are attached to the paddle wheel by means of profile arms ( 6 ) and screw connections ( 7 ). 30. Impeller according to claim 29, characterized in that the profile arms ( 6 ) represent at least two parallel, radially extending angle profiles, the profile arms having openings ( 7 ) outside the plane of the remaining angle profile for receiving screws. 31. Device ( 60 ) for arranging a counterweight, in particular for a floating paddle wheel aerator according to one of claims 1 to 15, characterized in that the device is a vessel ( 60 ) for filling a ballast material arranged in a float ( 3 ) opposite the motor.