Pump impeller with mixer

Abstract: The invention concerns a device for a pump provided with a mixing means (5). The driving shaft (3) of a pump impeller (4) is extended beyond the impeller and supports the mixer (5) at its end. In order to minimize the risk for extensive damages if the mixer should hit a solid body, the shaft (6) of the mixer is very slim and manufactured of an elastic material such as spring steel.

Description: The invention concerns a device for a pump according to the pre-characterizing part of Claim 1 and as disclosed in the document FR-A-2 470 268. When pumping liquids containing larger amounts of pollutions, certain problems arise. The pump impeller must be so designed that the pollutions do not clog the impeller and in addition the impeller as well as the surrounding housing must be manufactured of a material that can stand wear. This is especially important when pumping in mines where the water contains large amounts of wearing particles. When pumping in mines it also often occurs that the pollutions have settled and form a layer of a relatively solid consistence at the bottom. This layer cannot be pumped with conventional means, but must be transformed into a solution in one way or another. This may for instance be achieved by help of some sort of mixer. In order to eliminate the need for a separate mixer, there exist solutions where a pump is provided with an integrated mixer beyond the pump impeller and on the same shaft. The intention is that the mixer shall wreck the layer and make it to mix with the liquid above and thus make it possible to pump. Such a device has a good function as long as the sediment is not too solid or non-uniform. If this is the fact, the mixer shaft will be deflected when it hits harder material or lumps. If such deflections become too big, the shaft and its bearings might get damaged and cause expensive repair works. The purpose of this invention is to diminish the risks for damages which are difficult to repair. The characteristics are stated in the claims. The invention is described more closely below with reference to the enclosed drawing. In the drawing 1 stands for a driving unit and 2 a pump housing with a rotating pump impeller 4 on a shaft 3. 5 stands for a mixing means on a shaft 6 surrounded by a pipe 7. 8 stands for a bearing and 9 a fastening means for the shaft 6. The device according to the invention is thus arranged on a pump of centrifugal type and includes a pump housing 2 with a pump impeller 4 rotating therein. The shaft 3 of the impeller is supported by a lower bearing 8. Beneath the impeller 4 the shaft is provided with an extension 6 with a mixing means 5 formed like a number of blades on the shaft end. The shaft 6 is attached to the shaft 3 by help of the fastening means 9 in the area of the pump impeller 3 thus also serving as a fastening screw for the latter. The shaft 6 is very slim as compared to the shaft 3 and is manufactured of a steel having elastic qualities. The advantage is that the shaft 6 may be deflected when the mixing means 4 hits a solid body, without the bearing 8 for the shaft 3 being damaged. If the stress should be too strong, only the lower shaft 6 will be damaged. By designing its attachment 9 to the shaft 3 with a notch and by making it easy to demount, a replacement can be made without extensive costs. In order to maximize the deflection of the shaft 6, a pipe 7 is arranged around the shaft and attached to the shaft 3. As there is a certain play between the shaft and the pipe, the latter will not be influenced until the deflection reaches a certain value. If this should occur, the pipe will protect the other parts of the pump so that only the easily replaceable shaft 6 will be damaged.

Claims: A device for submersible pumps comprising a driving unit (1) and a pump housing (2) containing a rotating pump impeller (4) connected to the driving unit by a shaft (3) and a mixing means (5) beyond said impeller (4) and corotating with it, said mixing means being attached to the shaft (3) via an elastic shaft (6) having a diameter less than the shaft (3), characterized in that the shaft (6) is supported only at its end adjacent to the impeller and in that a part of the shaft (6) is surrounded by a pipe (7) with a play there between, which pipe is also attached to the shaft (3), said pipe preventing deflection of the shaft (6) exceeding a certain value depending on the play between the shaft (6) and the pipe (7), thus diminishing the risk for damaging other parts of the pump such as shaft (3), bearing (8) or impeller (4) when the shaft (6) deflects. A device according to claim 1, characterized in that the shaft (6) is attached to the shaft (3) by help of fastening means (9) in the area of the pump impeller (4), which means (9) is easy to demount, making a replacement possible without extensive costs.

Inventors: UVEMA PETER, UVEMA, PETER
Applicants: FLYGT AB ITT, ITT FLYGT AB
Application year: 1991
Main classification: F04D7
IPC codes: B01F7, F04D29, F04D7