Patent Application
20110003646
The invention relates to a drive device for immersed operation below a surface of a liquid, in particular for the immersed operation in a clearing basin.
In accordance with the prior art, agitator devices are used to circulate waste water received in a clearing basin. In this connection, one distinguishes between vertical agitator devices wherein, for example, a hyperboloid-like designed agitator body is rotated via a vertical drive shaft. In this connection, an electric motor that drives the drive shaft can either be attached above or below the surface of the liquid. Moreover, so-called horizontal agitator devices are known wherein an electric motor which is usually attached under the surface of the liquid rotates a propeller.
With agitator devices with a drive device attached below the surface of the liquid, it is necessary to seal the drive shaft which is guided out of a housing of the drive device in such a manner that no liquid can penetrate the housing. For this purpose, the drive shaft is usually guided through a sealing chamber on whose inlet a shaft seal is provided and on whose outlet which is facing the liquid an slide-ring seal is provided. An oil supply is usually received in the sealing chamber to lubricate the slide-ring seal.
In actual practice, the slide-ring seal must be maintained at regular intervals and, if necessary, must be replaced. This involves a significant amount of work since, in this case, the agitator device must usually be lifted out of the clearing basin and must be taken apart.
An object of the invention is to eliminate the disadvantages in accordance with prior art. In particular, a drive device is to be specified with which an immersed operation with an improved service life is possible. In accordance with another goal of the invention, maintenance of the drive device is to be as simple as possible and, in particular, damage in the area of the seal is to be easy to recognize.
This object is solved by the features of claims 1 and 11. Useful embodiments of the invention result from the features of claims 2 to 10 as well as 12 and 13.
According to the invention, it is provided that a line for receiving an oil supply is connected to the sealing chamber and is guided above the surface of the liquid. —With this, the service life of a drive device operated below a surface of a liquid can be significantly increased in a surprisingly simple way. By providing the sealing chamber with an oil supply that reaches up to above the liquid, it can be easily ensured that the sealing chamber is completely filled with oil at all times. The oil level in the sealing chamber can be easily checked. An impermissibly rapid decrease in the oil supply in the line indicates a defect in the slide-ring seal. Thus a repair of the slide-ring seal can be limited to the cases in which it is actually damaged. A further essential advantage of the invention is that a hydrostatic pressure is exerted on the oil received in the sealing chamber due to the oil supply reaching to above the surface of the liquid. With this, the oil in the sealing chamber is under a greater pressure than the liquid in the vicinity of the drive shaft. With this, an undesired penetration of liquid into the area of the slide-ring seal can be prevented. It can be ensured that the axial seal face is supplied with oil at all times.
According to an advantageous embodiment, the line is designed as transparent at least in a section located above the surface of the liquid. This makes a visual check simple and quick. With this, it can be immediately determined whether there is still enough oil in the line.
According to a further advantageous embodiment of the invention, the line is connected with a source of pressure for producing an overpressure exceeding the liquid pressure surrounding the sealing chamber. In this connection, the source of pressure is preferably provided above the surface of the liquid. That makes repairs and maintenance easier. The source of pressure is usefully a source of compressed air which is connected to the oil supply.
The source of pressure can also be a compressed air line. Particularly for sewerage treatment plants, such compressed air lines are positioned in the area of the agitator devices to aerate the clearing basin. Such a compressed air line is usually guided down to the bottom of the clearing basin and subjected to a pressure which enables air to exit in the area of the bottom of the clearing basin against the active pressure of the liquid. In contrast, the oil-filled sealing chamber of the drive device is immersed less deep in the liquid so that the pressure of the liquid in the vicinity of the sealing chamber is less than the air pressure in the compressed air line. Thus a connection of the line to the compressed air line provides a simple way to produce an overpressure in the sealing chamber which prevents an undesired penetration of liquid into the sealing chamber at all times. The line is advantageously guided over an essential part of its length essentially vertically, i.e., at an incline of more than 40°, along the compressed air line. Particularly in such a vertical section, it is connected with the compressed air line. In this connection, a connection location of the line on the compressed air line is usefully located at a height of 10 cm to 200 cm, preferably approximately 50 cm to 100 cm, above a level of the liquid.
According to a further embodiment of the invention, it is provided that the line is guided along the compressed air line at least in sections to the sealing chamber. The compressed air line is usually much more stable in design than the line. Damage or undesired tensile forces can be avoided by fixing the line to the compressed air line.
The line can be guided at least in sections along a cable providing the electric motor with current. Also in this case, an improved protection of the line against damages is achieved.
In the sense of this invention, the term “drive device” is to be understood as a general term. In this connection, it can be an electric motor. In this case, the drive shaft is part of the electric motor. The drive device can also be combined with a gear unit. In this case, the drive shaft is part of a gear unit driven by the electric motor.
The sealing chamber is usefully sealed with a shaft seal surrounding the drive shaft on a second side facing the electric motor or the gear unit. In this connection, this can be a conventional shaft seal, for example, a rotary shaft seal or similar, with which oil under overpressure is effectively prevented from leaving the sealing chamber.
In particular in the aforementioned case, the sealing chamber, the slide-ring seal and the shaft seal can be part of a sealing device designed as a mounting unit. Replacing such a sealing device is easy and quick. Separate disassembly of the seals received inside which is time-consuming and expensive is avoided.
According to further provisions of the invention, an immersible agitator is provided on which an inventive drive device is attached to a frame and wherein the drive shaft is connected to an agitator body. The agitator body can be a propeller or a hyperboloid agitator body. The drive shaft can be positioned horizontally or vertically with respect to a liquid surface. The frame can be part of a ventilation device and be connected with a compressed air line. In other words, the frame can be at least in sections designed as hollow so that compressed air can be guided down to the vicinity of the bottom of a clearing basin, for example.
The invention will now be described in more detail using an exemplary embodiment based on an agitator device. It is shown:
A compressed air hose 7 is attached to the frame 1 made of hollow pipes, in particular square pipes. Located below the agitator element 6 is a ring line 8 which is also connected to the frame 1 which ring line is provided with ventilation openings (not shown here). Air can thus be moved through the compressed air hose 7 through the frame 1 to the ring line 8 and from there through the ventilation openings to an area below the agitator element 6. The compressed air hose 7 can also be directly connected to the ring line 8 or to another suitable aerating element. In other words, the frame 1 does not have to be part of a ventilation device.
A cable 9 connected to the electric motor 3 is guided in sections along the compressed air hose 7 and is connected to the compressed air hose 7 in this section.
The function of the drive device is as follows:
The sealing chamber 10 being sealed by the slide-ring seal 12 and by the shaft seal 11 is filled with an oil, preferably a biologically degradable oil. The line 22 leading away from the sealing chamber 10 is also filled with oil. The oil received the line 22 represents an oil supply. The amount of oil supply received in the line 22 can be readily checked visually from the outside when the line is designed as transparent. For this purpose, the section of the line 22 located above the surface of the liquid F can be provided with a marking.
The oil supply and thus also the oil in the sealing chamber 10 is subjected to an overpressure by connecting the line 22 to the pressure hose 7 using the second connection element 23. The overpressure is greater than a pressure of a liquid acting on the slide-ring seal 12. Due to this, a small amount of oil continuously escapes through the slide-ring seal 12 in the direction of the surrounding liquid. With this, it is ensured at all times that no liquid, in particular no dirty liquid, can penetrate the slide-ring seal 12 and cause wear to same.
The inventive drive device was described before based on an immersible agitator. Naturally, the suggested inventive drive device can also be used for other purposes.
A connection of the line 22 to the compressed air hose 7 was described for simplicity's sake as a source of pressure in the present exemplary embodiment. Naturally, it is also possible to use other sources of pressure to produce an overpressure in the pressure chamber 10. For example, the overpressure can also be produced via a compressor or similar.
In the present exemplary embodiment, a volume given by the line 22 was described as the oil supply. Naturally, it is also possible to connect the line 22 to a supply tank or to provide a supply tank in the line 22.
The mounting unit described advantageously as a sealing device 9 in the present exemplary embodiment can also be part of a gear unit housing or a motor housing. In other words, it does not have to be designed as a mounting unit.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2007 013 630.9 | Mar 2007 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2008/002124 | 3/18/2008 | WO | 00 | 10/7/2009 |
