[0001] The present invention refers to a vortex impeller, able to be used on centrifugal
fluid-dynamic pumps operating horizontally, vertically and submersible.
[0002] Centrifugal fluid-dynamic pumps are the pumps most commonly used both in industry
and in civil applications. A centrifugal pump usually consists of a body on which
an intake mouth for the liquid to be pumped and a delivery mouth for conveying the
liquid in output are made, with a single impeller (single-stage pumps) or with many
impellers arranged in series (multi-stage pumps) .
[0003] The impeller, which constitutes the main element of a centrifugal pump, is nothing
other than a bladed wheel normally fitted onto a shaft actuated by a motor, generally
electric. The function of the impeller is to convert the energy developed by the motor
into kinetic energy for the liquid to be pumped.
[0004] When the liquid enters inside the pump body, the impeller projects such a liquid
to the periphery of the body itself and through the centrifugal force produced by
the rotation speed the liquid stores a potential energy in the form of pressure and
then changed into kinetic energy, in other words the maximum head of the liquid pumped
as well as generating a flow rate, i.e. the amount of liquid moved in a unit of time.
Moreover, such centrifugal movement simultaneously causes a depression capable of
sucking in the liquid to be pumped and connecting the pump with a delivery pipe, the
liquid shall be easily channelled and pushed to the outside of the pump itself.
[0005] The impeller of a centrifugal fluid-dynamic pump can be made according to many constructive
variants. Indeed, there are open impellers, closed impellers, semi-open impellers,
single-channel impellers, multi-channel impellers, axial impellers, semi-axial impellers,
spiral impellers, vortex recessed impellers, etc.
[0006] In the civil and industrial field pumps with open and semi-open recessed impellers
operating upon the principle of the liquid vortex, also known as hydraulic joint,
are widely used. This type of impeller is particularly suitable for pumping and transferring
dirty liquids, loads containing solids in suspension, muds also containing gases from
purification processes, industrial wastewater, rainwater and sewage water.
[0007] In literature and on the market there are numerous types of vortex recessed impellers,
equipped with open or half-open blades with a straight or curved profile. All known
vortex impellers of the aforementioned type share the characteristic of having a constantly
increasing area and section of the channel, in other words the substantially concave
zone shaped like a "pie-wedge" portion of a circle that is formed between one blade
and the next blade, starting from the starting point of the blades, arranged at the
eye of the impeller. Indeed, the area and section of the channel progressively increase
towards the outside in the radial direction, until the maximum outlet size of the
channel itself is reached at the outer circumferential edge of the impeller.
[0008] Whilst it has numerous advantages for the applications and services described above,
all open or semi-open vortex recessed impellers according to the prior art do, however,
suffer from a low hydraulic yield, especially compared to other types of single-channel
and multi-channel centrifugal impellers. This is because the particular configuration
of the blades and the position inside the pump body are such as to avoid to the greatest
possible extent the blocking due to the type of filled liquids to be pumped.
[0009] The general purpose of the present invention is therefore to make a vortex recessed
impeller for centrifugal fluid-dynamic pumps capable of achieving higher yields, in
terms of flow rate and head and for the same power of the pump on which it is installed,
with respect to all known vortex impellers, especially in the pumping of liquids with
a high impurity content and/or containing a large amount of solid residue.
[0010] Another purpose of the present invention is to make a vortex impeller for centrifugal
fluid-dynamic pumps that is simple and cost-effective to manufacture, as well as particularly
functional and adaptable to different types of centrifugal pumps present on the market.
[0011] In view of the aforementioned purposes, according to the present invention, it has
been thought of to make a vortex impeller for centrifugal fluid-dynamic pumps having
the characteristics outlined in the attached claims.
[0012] The structural and functional characteristics of the present invention and its advantages
compared to the prior art shall become even clearer from an examination of the following
description, referring to the attached drawings, which show a vortex impeller for
centrifugal fluid-dynamic pumps according to the innovative principles of the invention
itself.
[0013] In the drawings:
figures 1 to 4 are plan views of vortex impellers with known blade profiles;
figure 4B is a section view obtained along the line A-A of figure 4;
figure 5 is a plan view of a vortex impeller for centrifugal pumps according to the
present invention;
figure 5B is a section view obtained along the line A-A of figure 5;
figure 6 is a perspective view of the vortex impeller of figure 5; and
figures 7 and 8 show characteristic curves relative to different known impellers mounted
on pumps of equal power, compared with the characteristic curve (10) relative to the
use of a vortex impeller according to the present invention.
[0014] It should be specified that, in the following description and in the various figures
of the attached drawings, elements that are the same or equivalent to one another
are represented with the same reference numerals.
[0015] With reference to figures 1 to 4 of the attached drawings, some example embodiments
of vortex impellers known in the state of the art are shown.
[0016] In particular, figure 1 shows an impeller with open blades having a straight profile
orientated according to the spokes of the impeller itself, figure 2 shows an impeller
with open blades having a straight profile inclined tangentially with respect to the
eye of the impeller itself, figure 3 shows an impeller with open blades having a curved
profile according to a single predetermined arc of circumference, whereas figure 4
shows an impeller with half-open blades, i.e. with blades provided with a lip (see
the section view of figure 4B) and half-closed channels, again with a curved profile
according to a single predetermined arc of circumference.
[0017] In all of the known embodiments illustrated here, both the vortex impellers 1 with
straight blades, i.e. consisting of a straight segment (figures 1 and 2), and the
vortex impellers 1 with curved blades, consisting of an arc of circumference (figures
3 and 4) and provided or not with a lip for partially covering the channels between
the blades, share the characteristic of having the area A and the section S or width
of the channel 2 that is formed between one blade 3 and the next blade 4 that constantly
increase. Indeed, starting from the starting point 5 of each blade, arranged at the
central eye 6 of the impeller 1, and progressively moving towards the outer circumferential
edge 7 of the impeller 1 itself, the width S of each channel 2 shall take on ever
increasing values (S
1, S
2, ..., S
n) until the maximum size S
max is reached right at the outer edge 7 of the impeller 1, or output edge of each channel
2.
[0018] Now with reference to figures 5 and 6 of the attached drawings, a vortex impeller
for centrifugal pumps according to the present invention is shown, wholly indicated
with reference numeral 10 and able to be made from metallic material (cast iron, steel,
bronze) or else plastic.
[0019] The vortex impeller 10 is provided with a plurality of blades 12, 12' having respective
starting points 14, 14' arranged at the central eye 16 of the impeller 10 itself.
The impeller 10 also has an outer circumferential edge 18 at which the output profiles
20, 20' respectively of each blade 12, 12' are located. Each pair of contiguous blades
12, 12' thus defines an area 22 arranged between them, called the channel of the impeller
10.
[0020] According to the invention, each blade 12, 12' has a profile in plan consisting of
a plurality of arcs of circumference 24, 24', 24" arranged in sequence and joined
together, pairs of consecutive arcs of circumference 24, 24' or 24', 24" having different
bending radii.
[0021] Such a profile for the blades 12, 12' of the impeller 10, equipped with a particular
progressive inclination, makes it possible to obtain a section or size S of each channel
22 that does not constantly increase towards the outside, in other words towards the
edge 18 of the impeller 10 itself, as does on the other hand occur for known vortex
impellers (figures 1-4), where the maximum size S
max of the section of each channel 2 can be substantially defined at the outer edge 7
of the impeller 1.
[0022] On the other hand, in the vortex impeller 10 according to the present invention the
maximum size S
max of the section of each channel 22 or, in other words, the maximum linear distance
between pairs of blades 12, 12' contiguous to one another is reached in an intermediate
point P situated between the starting point 14, 14' of each blade 12, 12' and the
outer circumferential edge 18 of the impeller 10 itself. From such an intermediate
point P, the size of the section thus starts to decrease both in the direction of
the edge 18 (note for example the size S
2, smaller than the size S
max) and in the direction of the eye 16 of the impeller 10, until a size value S
3, measured at the output profile 20, 20' of each blade 12, 12', substantially equal
or close to the size value S
1 measured at the starting points 14, 14' of each pair of contiguous blades 12, 12'
is reached. In particular, in the illustrated example embodiment, the size values
S
1 and S
3 also coincide with the minimum width of each channel 22 measured outside of the eye
16 of the impeller 10.
[0023] From experimental tests, as can be seen from the head and flow rate characteristic
curved of figures 7 and 8, it has been found that, for the same power delivered and
size of the delivery mouth, centrifugal pumps equipped with a vortex impeller 10 according
to the present invention are able to reach yields about 20% รท 40% higher than when
they operate, in the same operating conditions, with the known vortex impellers currently
proposed on the market by the largest manufacturing firms. Although the comparison
has been carried out using submersible centrifugal pumps, incremental values similar
or equal to those displayed above can be reached by using the impeller 10 according
to the invention even on surface pumps, whether they operate horizontally or vertically.
[0024] Nevertheless, it should be understood that although the particular profile of the
blades of the impeller 10 according to the present invention has been illustrated
and described relative to a completely open impeller, it is also possible to apply
the same principle to half-open impellers, in other words of the type illustrated
in figures 4 and 4B, in which there is a lip formed in a single piece with each blade
that at least partially covers each channel.
[0025] From what has been described above with reference to the figures it is clear how
a vortex impeller for centrifugal pumps according to the invention is particularly
useful and advantageous. The purposes mentioned in the preamble of the description
are thus achieved.
[0026] In particular, the purpose of obtaining greater yields, in terms of flow rate and
head, compared to all known vortex impellers is accomplished, whereas in the pumping
of liquids with high impurity content and/or containing a large amount of solid residues
there is:
- the possibility of pumping liquids containing a substantial amount of gas without
cavitation phenomena occurring;
- the possibility of pumping liquids containing coarse solids and long fibres with less
risk of clogging;
- less wear; and
- lower axial thrust, with consequent reduction in the stress on mechanical support
and sealing parts on the shaft of the pump.
[0027] Of course, the shapes and sizes of the vortex impeller for centrifugal pumps according
to the invention can be different to the one shown as a nonlimiting example in the
drawings, just as the materials used can also be different.
[0028] The scope of protection of the invention is therefore defined by the attached claims.
1. Vortex impeller (10) for centrifugal fluid-dynamic pumps, provided with a central
eye (16), an outer circumferential edge (18) and a plurality of blades (12, 12') having
respective starting points (14, 14') arranged at said eye (16) of the impeller (10),
each pair of contiguous blades (12, 12') defining a channel (22) arranged between
them, characterised in that each of said blades (12, 12') has a profile in plan consisting of a plurality of
arcs of circumference (24, 24', 24'') arranged in sequence and joined together, pairs
of consecutive arcs of circumference (24, 24'; 24', 24") having different bending
radii.
2. Vortex impeller (10) according to claim 1, characterised in that the output profiles (20, 20') of each of said blades (12, 12') are located at said
outer circumferential edge (18) of the impeller (10).
3. Vortex impeller (10) according to claim 2, characterised in that the maximum linear distance between pairs of blades (12, 12') contiguous to one another,
equal to the maximum size (Smax) of the section of each of said channels (22), is reached in an intermediate point
(P) situated between said starting point (14, 14') of each blade (12, 12') and said
outer circumferential edge (18) of the impeller (10).
4. Vortex impeller (10) according to claim 3, characterised in that the size (S) of the section of each of said channels (22) decreases, starting from
said intermediate point (P), both in the direction of said outer circumferential edge
(18) of the impeller (10) and in the direction of said eye (16) of the impeller (10).
5. Vortex impeller (10) according to claim 3, characterised in that the size (S3) of the section of each of said channels (22) measured at said output profile (20,
20') of each of said blades (12, 12') is substantially equal or close to the size
(S1) of the section of each of said channels (22) measured at said starting points (14,
14') of each pair of blades (12, 12') contiguous to one another.
6. Vortex impeller (10) according to claim 5, characterised in that said size (S3) and said size (S1) coincide with the minimum width of each of said channels (22), measured outside
of said eye (16) of the impeller (10).
7. Vortex impeller (10) according to any one of claims 1 to 6, characterised in that it is an open impeller.
8. Vortex impeller (10) according to any one of claims 1 to 6, characterised in that it is a semi-open impeller, provided with a plurality of lips formed in a single
piece with each of said blades (12, 12') to at least partially cover each of said
channels (22).
9. Centrifugal fluid-dynamic pump operating horizontally, vertically and/or submersible,
characterised in that it comprises at least one vortex impeller (10) according to any one of the previous
claims.