JP4489119B2 - Impeller wheel - Google Patents

Description

  The present invention relates to a pump impeller, and more precisely to a pump impeller of a centrifugal or half axial pump that pumps a fluid holding contaminants.

  There are numerous types of pumps and pump impellers for this purpose described above in the literature, all of which have certain disadvantages. In particular, this relates to wear, clogging and low efficiency issues.

  Sewage holds a number of different types of pollutants, the amount and composition of which depends on the season and the type of area from which the water is drained. In cities, plastic materials, hygiene articles, fibers, etc. are common, while in industrial areas, wear particles will be generated. Experience has shown that the most problematic are rags and the like that adhere to the leading edge of the vane and wrap around the impeller hub. As a result of this situation, repairs are required at frequent intervals, thus reducing efficiency.

  In the agriculture and pulp industry, different types of specialized pumps are used that handle straw, grass, leaves and other types of organic materials. For this purpose, the leading edge of the vane is swept backward so that contaminants do not adhere to the edge and are supplied outward towards the periphery.

  Different types of separation means are often used to cut the material and make flow easier. Examples are shown in SE-435 952, SE-375 831 and US Pat. No. 4,347,035.

  In the literature, the design of the pump impeller is described very roughly, especially with regard to the sweep of the leading edge of the open impeller wheel. Attempts to define a leading edge sweep for an open impeller wheel are described, for example, in European Patent Specification 0916851 and European Patent Specification 0916852.

  For example, closed pump impellers are often used during pumping where high heads are required in mines. That is, since these types of impellers reduce the axial load on the pump compared to the open type impeller, such a pump having two cover discs, an upper disc and a lower disc, and an intermediate vane is used. Has been. On the other hand, a closed impeller has a small penetration, which means that there is a high risk of clogging.

  With respect to closed impeller wheels, these impeller wheels are generally designed with a leading edge located at the central inlet to be generally straight when viewed in the flow direction. In use, it has been found that the leading edge of the vane wears significantly, especially when the liquid retains a significant amount of abrasive contaminants. In addition, there is a risk that contaminants such as rags, plastic bags and other elongated objects may adhere to the leading edge, which necessitates cleaning of the pump.

  The object of the present invention is to eliminate the above-mentioned problems, in particular the problems associated with closed impeller wheels.

This object is solved according to the main form of the invention, which is the feature of claim 1. Preferred embodiments of the invention form the independent claims.
In accordance with the main form of the present invention, the present invention is a centrifugal or semi-shaft type impeller wheel used in a pump for pumping liquid, the impeller being arranged with one or several vanes, Is attached to the cover disc at each side, and in the impeller wheel forming a so-called closed impeller wheel, the vane's leading edge is swept backward at one inlet opening of the impeller cover disc The above-mentioned impeller wheel.

According to a further aspect of the invention, the leading edge is characterized by cooperating with cutting means located in the central inlet opening of the pump.
Preferably, the leading edge projects somewhat outwardly from the inlet opening, and the cutting means constitutes at least one narrow portion of the gap between the central inlet opening of the pump and the leading edge of the impeller Thus, during operation, when the leading edge sweeps these parts, a cutting action is realized between them.

  It has been found that by designing the leading edge so that the leading edge of the vane is swept back significantly, the wear on these edges is dramatically reduced. This design will also reduce the risk of material sticking to the edge. Such material is supplied towards the periphery.

  Nevertheless, the material that tends to adhere to the edge at the inlet opening of the impeller is cut by the cutting means. In one preferred embodiment, the leading edge of the vane cooperates with two narrow portions of the pump housing inlet opening.

  The sweep angle α is in the range of 40-60 °, and the leading edge sweep generally follows a logarithmic spiral curvature in order to obtain excellent performance in terms of pump function and transport of material toward the periphery. can do.

All impeller wheels provide improved performance and wear resistance, and increase the operating cycle during maintenance and repair.
These and other aspects and advantages of the present invention will become apparent from the following detailed description and accompanying drawings.

  In the following detailed description of the invention, reference will be made to the accompanying drawings.

  FIG. 1 shows a closed impeller wheel mounted in a pump with a drive shaft 10 connected to an electric motor (not shown) that drives the pump. A pump impeller 12 including an upper cover disc 14, a lower cover disc 16, a vane 18, and a rear vane 19 is attached to the lower end of the shaft. The components described above are mounted in a pump housing 20 having a bottom wall 22, an inlet 24 and an outlet 26. The pump impeller 12 is mounted as follows, that is, there is a gap 28 between the peripheral surface of the lower cover disk 16 and the inner wall of the pump housing 20 in the pump housing, and the lower disk. There is a space 29 between the bottom wall and the bottom wall, and a space 30 is provided between the lower surface of the lower cover disk 16 and the upper surface of the bottom wall 22.

According to the principle of the centrifugal pump, liquid is sucked axially through the inlet 24 and exits the pump through the outlet 26 according to the flow arrows A, B, C.
In accordance with the present invention, the vane 18 is designed such that the leading edge 40 is swept backwards significantly in the impeller wheel inlet opening 42 with respect to the direction of rotation R. The sweep angle can be increased from the hub and outward. The leading edge sweep can be defined by a logarithmic spiral, where the sweep angle α is π / 2-β when β is the logarithmic spiral angle. Preferably, the sweep angle is in the range of 40 to 60 °.

  At the impeller inlet opening, the leading edge is generally arranged in a plane perpendicular to the impeller axis of rotation 10. An advantageous effect of this design is that it ensures that the contaminants do not adhere to the edge but slide towards the periphery. It has further been found that when the impeller has this configuration rather than a conventional design, leading edge wear is reduced.

  Furthermore, the leading edge protrudes somewhat outward from the central opening of the impeller, see FIG. The edge portion 44 of the vane protruding beyond the bottom surface of the lower cover disc 16 can be arranged to cooperate with the edge portion 46 of the stationary inlet 24 of the housing located on the bottom plate 22. Thus, the circular inlet is arranged to have two oppositely arranged linear portions 50, so that the air gap between the vane and the inlet edge portion is very small. Elongated contaminants such as rags, plastic bags and the like attached to the leading edge of the vane will now be cut.

  Overall, a leading edge design that is swept and protrudes somewhat and that cooperates with the opening in the bottom plate will reduce the risk of contaminant deposition and reduce leading edge wear. .

  It should be understood that the embodiments described above and shown in the drawings are to be regarded as non-limiting examples of the invention and can be modified within the scope of the claims.

1 is an axial sectional view of a pump according to the present invention. 2a is a perspective view seen from above the impeller wheel constituting the present invention. 2b is a view from below corresponding to FIG. 2a. It is the figure seen from the downward direction of the impeller wheel of FIG. FIG. 2 is a view of the bottom plate mounted in the pump and cooperating with the impeller wheel according to FIG. 1.

Claims (7)

  A centrifugal or semi-shaft type impeller wheel (12) used in a pump for pumping liquid, the impeller being arranged with one or several vanes (18), with the vanes on each side In the impeller wheel (12), which is attached to the cover disk (14, 16) to form a so-called closed impeller wheel, the vane front edge (40) has an impeller cover circle with respect to the rotational direction (R). Swept backward at one inlet opening (42) of the plate (16), the leading edge (40) is perpendicular to the rotational axis (10) of the impeller (12) at the inlet opening (42). An impeller wheel characterized by being arranged in a flat plane as a whole.   The impeller wheel according to claim 1, wherein the leading edge (44) protrudes somewhat outwardly from the inlet opening (42) and is arranged with cutting means (50) arranged in the central inlet opening of the pump and Impeller wheel that can cooperate with the cutting means.   3. The impeller wheel according to claim 2, wherein the cutting means constitutes at least one narrow portion of the gap between the central inlet opening of the pump and the leading edge (40) of the impeller.   4. The impeller wheel according to claim 1, wherein the leading edge is swept according to a logarithmic spiral as a whole.   5. The impeller wheel according to claim 4, wherein the sweep angle ([alpha]) of the leading edge (40) is [pi] / 2- [beta] where [beta] is a logarithmic spiral angle.   The impeller wheel according to any one of claims 1 to 5, wherein the sweep angle (α) of the leading edge (40) is in the range of 40 to 60 °.   A pump comprising the impeller wheel according to any one of claims 1 to 3.

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