Impeller assembly for centrifugal pumps

Abstract

The present invention relates to an impeller assembly for centrifugal pumps, comprising a first disk-like element, operatively arranged towards a coaxial inlet, facing a second disk-like element with a smaller diameter, operatively arranged towards the outlet; this second disk-like element is rigidly connected to the first disk-like element through a set of angularly spaced blades, and is centrally provided with fastening means for fastening to a drive shaft. The distinctive feature of the present invention is that the blades comprise appendices, in flat sheet form, adjacent to the second disk-like element, which are essentially located in correspondence with areas subject to lesser axial thrust.

Claims

1. An impeller assembly for centrifugal pumps, comprising a first disk-like element, operatively arranged towards a coaxial inlet of a pump and facing a second disk-like element, the second disk-like element having an outer diameter smaller than an outer diameter of the first disk-like element, the second disk-like element being operatively arranged towards a delivery of said pump; said second disc-like element being rigidly connected to said first disk-like element through a set of angularly spaced blades, and being centrally provided with a hub configured to fasten to a drive shaft; wherein the set of angularly spaced blades comprise appendices, in flat sheet form, adjacent to said second disk-like element, each appendix is constituted by a folded portion of the corresponding blade; said folded portion extends transversally to the corresponding blade substantially in correspondence of a fold line at an edge of the corresponding blade, said appendices and said second disk-like element are coplanar.

2. An impeller assembly, according to claim 1, wherein each appendix is in one piece with the corresponding blade.

3. An impeller assembly, according to claim 1, wherein each appendix is delimited by at least a first side defined by said fold line, by at least a second side adjacent to a peripheral edge of said second disk-like element, and by at least a shaped side joined to said first and second sides.

4. An impeller assembly, according to claim 3, wherein said shaped side comprises at least two segments; said segments being consecutive and transverse to each other.

5. An impeller assembly, according to claim 3, wherein said shaped side comprises a succession of substantially straight segments.

6. An impeller assembly, according to claim 1, wherein the appendices are located radially outwardly of the second disk-like element.

7. A centrifugal pump comprising a substantially hollow body which accommodates at least one impeller assembly fastened to a transmission shaft which is rotatable about a rotation axis; said transmission shaft being rotated by a motor; the at least one impeller assembly comprising a first disk-like element, operatively arranged towards a coaxial inlet of said pump and facing a second disk-like element, the second disk-like element having an outer diameter smaller than an outer diameter of the first disk-like element, the second disk-like element being operatively arranged towards a delivery of said pump; said second disc-like element being rigidly connected to said first disk-like element through a set of angularly spaced blades, and being centrally provided with a hub configured to fasten to said transmission shaft; wherein the set of angularly spaced blades comprise appendices, in flat sheet form, adjacent to said second disk-like element, each appendix is constituted by a folded portion of the corresponding blade; said folded portion extends transversally to the corresponding blade substantially in correspondence of a fold line at an edge of the corresponding blade, said appendices and said second disk-like element are coplanar.

8. An impeller assembly, according to claim 7, wherein the appendices are located radially outwardly of the second disk-like element.

9. An impeller assembly for centrifugal pumps, comprising a first disk-like element, operatively arranged towards a coaxial inlet of a pump and facing a second disk-like element with a smaller diameter, operatively arranged towards a delivery of said pump; said second disc-like element being rigidly connected to said first disk-like element through a set of angularly spaced blades, and being centrally provided with a hub configured to fasten to a drive shaft; wherein the set of angularly spaced blades comprise appendices, in flat sheet form, adjacent to said second disk-like has been changed to element, wherein each appendix is constituted by a folded portion of the corresponding blade; said folded portion extends transversally to the corresponding blade substantially in correspondence of a fold line at an edge of the corresponding blade, wherein each appendix is delimited by at least a first side defined by said fold line, by at least a second side adjacent to a peripheral edge of said second disk-like element, and by at least a shaped side joined to said first and second sides, said shaped side comprises a curved portion having a concavity facing the outside of said second disk-like element.

10. An impeller assembly for centrifugal pumps, comprising a first disk-like element, operatively arranged towards a coaxial inlet of a pump and facing a second disk-like element with a smaller diameter, operatively arranged towards a delivery of said pump; said second disc-like element being rigidly connected to said first disk-like element through a set of angularly spaced blades, and being centrally provided with a hub configured to fasten to a drive shaft; wherein the set of angularly spaced blades comprise appendices, in flat sheet form, adjacent to said second disk-like element, wherein each appendix is constituted by a folded portion of the corresponding blade; said folded portion extends transversally to the corresponding blade substantially in correspondence of a fold line at an edge of the corresponding blade, wherein each appendix is delimited by at least a first side defined by said fold line, by at least a second side adjacent to a peripheral edge of said second disk-like element, and by at least a shaped side joined to said first and second sides, said shaped side comprises a curved portion having a convexity facing the outside of said second disk-like element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further features and advantages will become apparent from the detailed description of the preferred embodiments of an impeller assembly according to the invention, illustrated in the attached drawings, where:

(2) FIG. 1 is a front view of an impeller assembly according to the invention;

(3) FIG. 2 is an enlarged perspective view of a detail of the impeller assembly of the previous figure;

(4) FIG. 3 is a front view of an impeller assembly according to a further aspect of the invention;

(5) FIG. 4 is a front view of an impeller assembly according to still a further aspect of the invention.

DESCRIPTION OF THE EMBODIMENTS

(6) With reference to FIGS. 1 and 2, an impeller assembly for centrifugal pumps, according to the invention, is generally indicated with the reference number 1.

(7) The impeller assembly 1 is designed for a multi-stage centrifugal pump; however, it is evident for any person skilled in the art that the impeller assembly of the present invention is also suitable for other types of pumps.

(8) The multistage centrifugal pump, which is per se known and is not shown in the figures, comprises a substantially hollow body which accommodates in its interior a set of impellers, made according to the present invention, and coaxially mounted on a drive shaft rotating by motor means.

(9) The impeller assembly 1 comprises a first disk-like element 2, operatively arranged at the pump inlet side, and a second disk-shaped element 3, operatively arranged at the pump delivery side.

(10) The diameter of the second disk-like element 3 is smaller than the diameter of the first disk-like element 2.

(11) The two disc-like elements 2 and 3 are coaxial to a rotation axis 1000, and are facing each other in such a way as to form a cavity of a substantially cylindrical shape.

(12) Blades 4 are arranged inside the cavity. Each blade 4 is substantially flat and oblong and rigidly connects the first disk-like element 2 to the second disk-like element 3.

(13) The blades 4 are angularly distributed around the rotation axis 1000, extending from the center to the peripheral area of the two disk-like elements 2 and 3.

(14) The blades 4 are arranged following a substantially spiral arcuate profile, without jutting out the first disk-like element 2, in such a way as to form radially arranged divergent ducts.

(15) Advantageously, the second disk-like element 3 is provided with fastening means to a drive shaft, not shown in the figures, which is rotatable about the rotation axis 1000.

(16) In the illustrated example, the fastening means are essentially constituted by a hub 5 in the middle of the second disk-like element 3.

(17) Opposed to hub 5, a through hole 6 is centrally formed on the first disk-like element 2 and has a larger diameter than that of the drive shaft.

(18) The through hole 6 in fact constitutes the suction inlet of the impeller assembly 1.

(19) According to the present invention, each blade 4 comprises an appendix 7, in flat sheet form, placed at its edges.

(20) Advantageously, the appendix 7 is in one piece with the corresponding blade 4, and consists of a shaped portion of the blade 4, that is folded along a fold line 8.

(21) The folds are made in such a way that each appendix 7 extends transversally to the corresponding blade 4.

(22) In practice, when the blades 4 are mounted on the impeller assembly 1, the appendices 7 are parallel and coplanar to the second disk-like element 3.

(23) Each appendix 7 has a side 9 resting on the second disk-like element 3, and extends inside of a circular crown coplanar to the second disk-like element 3; the circular crown is comprised within circumferences having diameters respectively coincident with those of the two disk-like elements 2 and 3.

(24) It should be noted that the appendices 7 are placed substantially in correspondence of the areas subject to lesser axial thrust inside the aforesaid circular crown.

(25) Each appendix 7 is also delimited by a shaped side that joins to the side coinciding with the fold line 8 and the side 9 which rests on the edge of the second disk-like element 3.

(26) In the embodiment shown in FIGS. 1 and 2, the shaped side is constituted by a pair of segments 10a and 10b, consecutive and transverse between them.

(27) In practice, the perimeter of each appendix 7 substantially has the shape of a circular crown sector.

(28) However, as will appear evident to person skilled in the art, the aforementioned appendices may vary in size and in shape, without departing from the scope of the invention.

(29) In fact, for example, FIG. 3 shows an impeller assembly, generally indicated with reference number 101, substantially similar to impeller assembly 1, but in which each appendix 107 is provided with a shaped side consisting of two segments 110a and 110b, that follow each other with a different angle.

(30) It should also be noted that the shaped side may be discretized into a set of consecutive segments, differently positioned between them, which, at the limit, may also have the appearance of a curved portion.

(31) FIG. 4, for example, shows an impeller assembly, generally indicated with reference number 201, substantially similar to impeller assemblies 1 and 101, where however the appendices 207 are equipped with a shaped side including a straight portion 210a and a curved portion 210b, with the concavity facing outside of the second disk-like element 3.

(32) According to another embodiment, not illustrated in the figures, the shaped side includes a convex portion.

(33) It is clear how the appendices may vary in a manner substantially equivalent in shape, size and proportions, without departing the scope of the invention.

(34) In the embodiments shown in FIGS. 3 and 4, the elements corresponding to those already described with reference to the embodiment shown in FIGS. 1 and 2 have been identified with the same reference numbers.

(35) The impeller assembly, according to the invention, can be manufactured using various techniques, using metallic materials such as, for example, steel, stainless steel and similar, or other materials having the required technical features.

(36) Regarding the operation of the impeller assembly according to the present invention, experimental tests and a careful analysis of resulting data have revealed that the presence of these appendices implies a greater fluid dynamic performance and a good prevalence, given the same axial thrusts reduction.

(37) In practice, it has been observed that the impeller assembly according to the invention fully achieves the intended aim, reducing the axial thrusts and at the same time ensuring maximum efficiency and prevalence.

(38) This is achieved by having the appendices covering only the areas subject to lesser axial thrust, relative to the circular crown coplanar to the second disk-like element, and corresponding to circumferences with diameters respectively coincident with those of the two disk-like elements.

(39) The one piece construction of the appendices and blades allows to use two disk-like elements which do not need to be installed in precise reciprocal angular positions.

(40) This allows to simplify and speed up the manufacturing process of the impeller assembly according to the invention, making it clearly more advantageous also from a merely economical point of view.

(41) In practice, materials employed, so long as compatible with the specific use, as well as the contingent size and shapes, can be any according to the requirements and the state of the art.

(42) This application claims the priority of Italian Patent Application No. 102015000013754, filed on 4 May 2015, the subject matter of which is incorporated herein by reference.