Abstract:
In a device ( 1 ) for treating waters in a basin, an operating group ( 8 ) is immersed in the water, being supported by two upper floats ( 3 ) or simply resting on the bottom of the basin. The operating group ( 8 ) has, defined inside it, a chamber inside which it is possible to create a pressure drop by means of a propeller ( 10 ) rotating outside the chamber. Two suction pipes ( 6 ), which lead to the chamber, emerge at the top above the free surface of the water. The operating group ( 8 ) is attached to a base structure ( 12 ) which is able to rest on the bottom of the basin. The device ( 1 ) may be used in particular to aerate and/or oxygenate (by means of movement) the waters contained in a basin, such as for example a tank for aquiculture, a fish-farming basin or an aeration tank of water purification plants.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a device for treating water in a basin. 
     More specifically, but not exclusively, the invention is advantageously used in different types of basins, such as, for example, tanks for aquiculture, fish-farming basins, aeration tanks of water purification plants, lakes undergoing reclamation, etc. The device in question may be used in particular for aerating and/or oxygenating the water, but it may also serve for other types of water treatment, such as, for example, stirring, degassing, destratification, de-icing, remixing, etc. 
     2. Description of the Prior Art 
     Various types of apparatus which perform the abovementioned tasks are already known; some of these are illustrated, for example, in the following patent publications: DE 3,417,039, EP 0,088,850, U.S. Pat. No. 4,157,304, U.S. Pat. No. 4,409,107, U.S. Pat. No. 4,514,343, U.S. Pat. No. 4,732,682, U.S. Pat. No. 4,741,825, U.S. Pat. No. 4,882,099, U.S. Pat. No. 4,954,295 and U.S. Pat. No. 5,118,450. 
     In particular the present invention refers to a device provided with an operating group immersed in the water and comprising a decompression chamber, a rotating propeller and a motor for driving the propeller. The decompression chamber has an inlet communicating with a suction duct which emerges above the free surface of the water, and an outlet immersed in the water; the propeller is situated outside the decompression chamber in the vicinity of the outlet. During use, operation of the propeller empties the decompression chamber of the water and causes, via the suction duct, sucking-in of air which is mixed with the water in the basin. 
     A device of this type is already known from the European publication EP 0,562,314 which illustrates a floating structure made of plastic material and comprising two parallel, hollow, floating cables underneath which the operating group is located. This device has, however, certain drawbacks. 
     Firstly, in the case where the level of the water inside the basin falls, the operating group may touch the bottom, with the consequent incorrect operation or breakdown of the device. 
     Secondly, when the device is outside the water—for example so that operations such as storage, transportation, checking, maintenance, etc., may be performed—the motor is exposed to accidental knocks with the risk of damage. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is that of providing a device which is able to overcome the abovementioned drawbacks. 
     One advantage of the invention in question is that of providing a device which is particularly stable both inside and outside the water. 
     Another advantage is that, even when the device is outside the water, the operating group is protected against accidental knocks. 
     A further advantage is that of eliminating the risk that, in the event of a considerable drop in the level of the water inside the basin, the operating group may touch the bottom of the basin itself. 
     Yet another advantage is that, in a device constructed in accordance with the invention, it is possible to adjust easily, and over a wide range, the arrangement of the axis of rotation of the propeller; in particular, the device may selectively operate with the axis of the propeller horizontal, vertical or inclined at different angles. 
     A final advantage consists in the fact that the device is able to operate also without the aid of a floating structure, when it is simply rested on the bottom of the basin. 
     These objects and advantages are achieved by the invention in question, as is characterized by the claims indicated below. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is described below in detail with reference to the accompanying figures, which illustrate a preferred embodiment thereof. 
     FIG. 1 shows a schematic, partial, vertical elevation view of an example of embodiment of the device in question; 
     FIG. 2 shows, on a larger scale, a cross-section along the horizontal plane indicated by II—II in FIG. 1; 
     FIG. 3 shows, on a smaller scale, a cross-section along the plane indicated by III—III in FIG. 2; 
     FIGS. 4 and 5 show two different operating configurations of the device, with the operating group differently oriented; 
     FIG. 6 shows a detail of FIG. 3, on a larger scale and cross-sectioned; 
     FIG. 7 shows the device according to FIG. 3, slightly modified and in a different operating condition (tipped over), and resting on the bottom of the basin. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to the abovementioned Figures,  1  denotes in its entirety a device, constructed in accordance with the present invention, for treating a mass of water contained in a basin. 
     The device  1  comprises a floating structure  2  comprising two hollow, parallel and spaced floats  3  which are made of a plastic material and joined together by a horizontal flat element  4 . The latter is made of plastic material and formed as one piece with the floats  3 . The floating structure  2  has two sliding guides  5  with a vertical sliding axis. Each guide  5  is integral with a respective float  3 . Two respective pipes  6  with a vertical axis are slidably coupled with the sliding guides  5 . At the top, each pipe  6  terminates in an inlet mouth which is covered by a dome-shaped protection piece  7  which is open at the bottom. Each protection piece  7  prevents the entry, from above, of objects into the inlet mouth and at the same time allows the entry of air into the respective pipe  6  via the mouth itself, passing through an annular opening defined between the pipe and the associated protection piece, as indicated by the arrows F. Locking means, which are known and not shown, are provided for selectively fixing in position the pipes  6  with respect to the sliding guides  5 . 
     The floating structure  2  was immersed in the water, an operating group indicated in its entirety by  8 . The operating group  8  comprises at least: a decompression chamber  9 , a rotating propeller  10  and a motor (known and not shown) for driving the propeller. 
     The device  1  also comprises a base structure  12  which is immersed in the water and to which the operating group  8  is attached. The bottom ends of the pipes  6  are rigidly engaged with the base structure  12 . 
     Said structure  12  may be made of plastic material, for example the same material from which the floats  2  are made. The base structure  12  consists in the case in question in two lateral support elements  13  which are arranged alongside each other and substantially extend in a vertical plane and are specularly symmetrical. 
     These elements  13  are internally hollow, are parallel and spaced from one another and are joined together by one or more horizontal cross-pieces  14 . Each support element  13  has in a central zone a weight-reducing opening  15 , so that overall the shape of each element  13  is substantially annular. The operating group  8  is arranged in the space between the two support elements  13 . 
     This base structure  12  is provided with at least three bottom resting points which are located underneath the operating group  8  and by means of which the device  1  may be rested on top of an external solid surface. 
     Each support element  13  is provided at the base with two support feet  17 , the bottom surface of which is relatively wide and has at least one of the abovementioned resting points  16 . Therefore, in the case in question, the base structure  12  has four support feet  17  with which at least one possible bottom resting point  16  is associated. 
     Externally, the base structure  12  is provided with at least three lateral resting points  18  which are situated alongside the operating group  8  and by means of which the structure  12  may be laid with one side on top of an external solid surface, as illustrated in FIG.  7 . In this particular case, there are at least four lateral resting points  18 , two of which are arranged on the side surface of two bottom support feet  17 ; another two lateral resting points  18  are arranged on another two further support feet  19  which are located laterally on the top zone of the two support elements  13 . The abovementioned lateral resting points  18  are situated on the opposite side to the propeller  10 . 
     The operating group  8  has at least two ends  20 ,  21  which are joined to the base structure  12 . In the particular case, a first end  20  is rotatably coupled to the base structure  12 , with the axis of rotation x—x preferably horizontal, and a second end  21  can be positioned on the base structure. In particular the second end  21  is removably fixed to one of the cross-pieces  14  which join the two support elements  13 . The position of this cross-piece  14  and the second end  21  of the operating group associated with it is adjustable: for this purpose, the opposite ends of this cross-piece  14  may be fixed to the support elements  13  in a plurality of different positions: in fact, a plurality of fastening points  22  are positioned on an arc of a circle, with which points the ends of the cross-piece  14  may be engaged. These fastening points  22  are present on both the support elements  13  and are arranged circumferentially around the axis of rotation x—x of the operating group  8 . 
     The operating group  8  comprises a cylindrical part  23  which is sealingly closed with respect to the exterior and contains a known motor  23 ′ which can be of the electric or fluid-operated type. The decompression chamber  9  is defined by the walls of a casing  24 . This chamber  9  has at least one inlet  25  and at least one outlet  26 . In the case in question the chamber  9  has two opposite side inlets  25 . 
     Each side inlet  25  communicates with a suction duct  28  comprising a channel  29  formed inside a respective support element  13 . Each channel  29  has an end communicating with the decompression chamber  9  and an opposite end communicating with one of the two vertical pipes  6  which emerge above the free surface of the water. The bottom end of each pipe  6  is attached to a respective support element  13  and has a mouth communicating with the channel  29  inside said element. Therefore the suction ducts  28  are formed, at least partly, inside the base structure  12 . 
     A water-tight container  11  contains electrical power supply terminals of the electric cable  30  which penetrates inside the casing  24  of the motor by means of the sealed connector  27 . 
     The outlet  26  of the decompression chamber is immersed in the water. The rotating propeller  10  is situated completely outside the decompression chamber  9  in the vicinity of the outlet  26 . The side inlets  25  of the decompression chamber are situated in the vicinity of the axis x—x about which the operating group  8  is able to rotate. The propeller  10  is connected to the motor by means of a shaft  31  which passes through the decompression chamber  9 . 
     One end  32  of the shaft  31  is integrally joined, by means of keying, to a hub  33  which carries the propeller  10  and which is situated opposite the outlet  26  of the decompression chamber. This end  32  of the shaft has a sealed-closing cap  34  which is housed inside a cavity of the hub  33  and is designed to prevent infiltration of water into the space between the joining surfaces of the shaft  31  and the hub  33 . The latter has, inside it, channels  35  with their axis parallel to the axis of rotation of the propeller  10  and arranged circumferentially about said axis. These channels  35  connect the decompression chamber  9  to an air outlet opening  36  which is formed centrally inside the hub  33 . 
     The shaft  31  has a first section  37  which is surrounded by an annular chamber  38  sealingly closed and delimited by walls of the casing  24 . The annular chamber  38  is intended to contain a lubricating fluid (oil). The shaft  31  also has a second section  39  which acts as a pivot for rotation and which has, coupled to it, a rolling support  40  consisting for example of a conventional ball-bearing system. The first section  37  of the shaft is located between the end  32  with the hub  33  and the second section  39  with the rolling support  40 . The first section  37  has, mounted on it, first sealing means  41  which are designed to close off sealingly the annular chamber  38  full of oil both from the decompression chamber  9  and from the rolling support  40 . The decompression chamber  9  has, arranged inside it, second sealing means  42  which are designed to close off further in a sealing manner the connection between the annular chamber  38  and the decompression chamber  9 . 
     The first sealing means  41  comprise: a first annular gasket  43  which is made of elastomeric material, is fixed and has an L-shaped cross-section and is seated so as to make contact with the shoulder of the casing  24 ; a first ring  44  which is made of ceramic material, is fixed and seated in the cavity of the first annular gasket  43 ; a first annular sealing member  45  which is made of graphite, is rotationally integral with the shaft  31  and is intended during use to form a sliding-contact seal against the first ring  44 . The first sealing means  41  also comprise a group of elements which is composed of a second annular gasket  46 , a second ring  47  and a second annular sealing member  48  which are identical and symmetrical with respect to the similar elements  43 ,  44 ,  45  indicated previously. A resilient member  49  (spring) and a sleeve  50  made of elastomeric material are arranged between the two groups of elements. The resilient member  49  ensures the sliding contact between the rings  44 ,  47  made of ceramic material and the annular sealing members  45 ,  48  made of graphite. The resilient sleeve  50  surrounds coaxially a section of the shaft  31 . A tubular-shaped lining sheath  51 , made of nylon, snugly lines the external surface of a portion of the shaft  31 . 
     The second sealing means  42  comprise an annular element  52  which is preferably made of rigid plastic (Teflon) and which lines a part of the shaft  31  and is rotationally integral with the latter. One end  53  of the annular element  52  is gripped with contact between the hub  33  and the shaft  31 , while the opposite end has an annular lip  54  which makes sealing contact against a fixed surface of the casing  24 . A middle part  55  of the annular element  52  surrounds, with contact, an end part of the tubular lining sheath  51 . The cap  34  and the annular element  52  co-operate so as to protect the shaft  31  from contact with the water contained in the basin: it is possible to provide, as an addition or as an alternative, other means which are able to insulate, from the water, the end of the shaft which carries the propeller  10  and which passes through the decompression chamber  9 : it has been found that the use of insulating means reduces considerably corrosion phenomena affecting the shaft itself. 
     During use, the motor causes rotation of the propeller  10 , resulting in the water which initially fills the decompression chamber  9  being sucked out. The latter is emptied of the water. A drop in pressure occurs inside the chamber  9 , with the consequent suction of air (and/or oxygen and/other substances) from outside through the various suction ducts  6 ,  29 ,  30 . The sucked air, to which oxygen is added if necessary, is then sucked up through the channels  35  in the hub  35  and then mixed with the mass of water contained in the basin. 
     FIG. 7 shows a particular operational configuration of the device, in which the operating group  8  is arranged with the axis of rotation of the propeller  10  vertical: in this case the base structure  12  is rotated through 90° with respect to the configuration in FIG.  3  and is connected to the vertical suction pipes  6  by means of 90° elbow connectors  56  which can be removably fitted if required. 
     In the case where the water level in the basin drops considerably, the base structure  12  is able to rest, with its bottom support feet  17 , on the bottom of the basin, so that the operating group  8  never manages to touch the bottom itself, thus eliminating the risk of damage or malfunctions. It is also possible to use the device  1  without the need for a top floating structure  2 : in this case the base structure  12  is rested on the bottom of the basin and the operating group  8  is able to operate, since it is nevertheless located at a distance from the bottom itself. The motor is preferably mounted on supports made of elastomeric material, mainly with the aim of reducing the vibrations when the device, during operation, is not floating on the water, but is resting on a solid surface. 
     In the case where the operational configuration is the one tipped over on its side as shown in FIG. 7, the bottom support is provided by the resting points  18  which are situated laterally on the opposite side to the propeller  10 . 
     As is known, by sliding the pipes  6  along the respective guides, it is possible to adjust the depth at which the operating group  8  is located, while keeping the top end of the pipes themselves above the free surface of the water. It is also possible to adjust the orientation of the operating group  8  in a vertical plane: FIGS. 4 and 5 show, purely by way of example, two different possible orientations of the operating group  8  in a vertical plane. 
     The adjustment of the depth and the orientation of the operating group allow the device to be used to perform various functions such as, for example, aeration, degassing, circulation, destratification and de-icing. 
     Owing to the base structure  12 , the operating group  8  can be supported with a considerable degree of stability. The base structure  12 , moreover, being floating per se, helps lighten the weight of the device in the water. The base structure  12  also provides protection for the operating group  8  when the device is not in the water; in this connection it must be pointed out that the operating group  8  is enclosed within the dimensions of the base structure  12  both in the vertical and in the horizontal direction. 
     Finally, owing to the structure  12 , the operating group  8  is also able to function without the aid of the floats, when said structure is simply rested on the bottom, as for example shown in FIG.  7 . In this case, the suction ducts  28  may simply emerge slightly above the free surface of the water, without being attached to any floating structure. 
     Obviously the constructional details of the invention may be subject to numerous other modifications of a practical and applicational nature, without thereby departing from the protective scope of the inventive idea claimed below.