EP2916008A1

EP2916008A1 - Improved electric pump particularly suitable for pumping liquids containing solid impurities

Info

Publication number: EP2916008A1
Application number: EP15158048.7A
Authority: EP
Inventors: Giuliano Matteazzi; Fiorenzo Zamberlan
Original assignee: Calpeda SpA
Current assignee: Calpeda SpA
Priority date: 2014-03-07
Filing date: 2015-03-06
Publication date: 2015-09-09
Anticipated expiration: 2035-03-06
Also published as: EP2916008B1

Abstract

Electric pump (1) comprising: a tubular jacket (2) developing according to a longitudinal direction (X), provided with an inlet mouth (3) and an outlet mouth (4) for the passage of a liquid; a multistage pumping device (15) arranged in the tubular jacket (2) and delimited by a tubular casing (6) separated from the tubular jacket (2) by means of an interspace (9), the tubular casing (6) being provided with a suctioning mouth (7) communicating with the inlet mouth (3) and a delivery mouth (8) communicating with the interspace (9), the pumping device (15) being actuated by a driving device (16) arranged in the tubular casing (6) for pumping the liquid from the suctioning mouth (7) towards the delivery mouth (8); sealing means (10) arranged in the interspace (9) in intermediate position between the suctioning mouth (7) and the delivery mouth (8) for preventing the liquid from flowing from the delivery mouth (8) towards the suctioning mouth (7), the sealing means (10) being arranged between the diffuser unit and the delivery mouth (8) according to the longitudinal direction (X).

Description

The present invention regards an electric pump particularly suitable for pumping liquids containing solid impurities.
Electric pumps of the type comprising a tubular jacket provided with an inlet mouth and an outlet mouth for the liquid to be pumped are known.
The tubular jacket encloses a pumping unit for suctioning the liquid from the inlet mouth and conveying it towards the outlet mouth, which has the opposite ends constrained to the tubular jacket so as to prevent the axial movement thereof.
The pumping unit is delimited by a tubular casing, in which an electric motor and one or more rotors, mutually connected by means of a shaft, are arranged. The tubular casing is arranged coaxially to the aforementioned tubular jacket and separated therefrom by means of an interspace.
In addition, the tubular casing is provided with a suctioning mouth communicating with the inlet mouth of the tubular jacket and a delivery mouth communicating with the aforementioned interspace.
Thus, the pumped liquid flows along the interspace and cools the electric motor.
The pumping unit is configured so that it can be inserted into the tubular jacket along its longitudinal axis and constrained at the two opposite ends of the tubular jacket, so as to prevent the axial displacement.
The aforementioned configuration allows assembling the electric pump.
In addition, the electric pump comprises sealing means arranged in the interspace, having the function of preventing the liquid exiting from the delivery mouth from returning towards the suctioning mouth along the interspace, thus reducing the efficiency of the electric pump.
According to the prior art, the aforementioned sealing means are arranged at the end of the tubular casing facing towards the inlet mouth of the tubular jacket, so as to be able to use the element for connecting the tubular casing to the tubular jacket also as a support for the sealing means.
The electric pump of the type described above is generally used for suctioning liquids from wells or vats and it is arranged with the inlet mouth facing downwards, so as to be directly submerged in the liquid.
The aforementioned electric pump reveals a drawback lying in the fact that, in presence of liquids containing solid impurities, the latter tend to sediment in the interspace area which, during use, is arranged further below, i.e. the area comprised between the delivery mouth of the tubular casing and the aforementioned sealing means.
More precisely, during operation, the interspace is filled with the pumped liquid, which is kept in movement by the outflow of the fluid through the delivery mouth of the tubular casing as long as the pumping unit is running.
When the electric pump is stopped, the liquid stops, allowing the sedimentation of the residual impurities in the interspace, the impurities progressively filling the lower area of the interspace.
After a given number of consecutive starts and stops, the lower area of the interspace is entirely filled with sediments which tend to solidify forming scales over time.
The aforementioned scales cause the drawback of complicating or, even, preventing the disassembly of the electric pump, for example required for maintenance.
As a consequence, there arises the drawback lying in the fact that some components of the electric pump may be damaged during the disassembly operation, requiring the replacement thereof. In the worst cases, it may be impossible to disassemble the electric pump and thus there arises the need to entirely replace it.
The aforementioned drawbacks are particularly frequent in the typical uses of the electric pumps of the type described above, given that the water suctioned from the wells may contain mud, while the re-circulated industrial liquids, for example oil for machine tools, often contain metal processing residues. The present invention has the object of overcoming the aforementioned drawbacks of the electric pumps of the known type.
In particular, an object of the present invention is to provide an electric pump of the type described above which may be easily disassembled even after a long period of use in presence of liquids containing solid impurities.
In particular, an object of the present invention is to prevent the formation of scales deriving from the sedimentation of the impurities.
The aforementioned drawbacks are attained by an electric pump obtained according to the main claim.
Further detailed characteristics of the electric pump of the invention are outlined by the relative dependent claims.
Advantageously, the prevention of the scales prevents both the damaging during the disassembly operations, thus reducing the need of replacing the relative components, and the need of replacing the entire electric pump like in the case of the electric pumps of the prior art.
The aforementioned objects and advantages, alongside others to be mentioned hereinafter, shall be outlined during the description of a preferred embodiment of the invention provided, by way of non-limiting example, with reference to the following attached drawings, wherein:

fig. 1 represents the electric pump of the invention, in sectional view according to a longitudinal plane;
fig. 2 represents an enlarged detail of fig. 1.

The electric pump of the invention, represented, in figure 1 with reference 1 is particularly suitable for pumping liquids containing solid impurities which tend to sediment, thus generating scales.
Therefore, the electric pump 1 is particularly suitable to be used in wells, or for the re-circulation of industrial liquids, or similar applications.
The electric pump 1 comprises a tubular jacket 2 developing according to a longitudinal direction X, provided with an inlet mouth 3 and an outlet mouth 4 for the liquid to be pumped.
A pumping unit 5, which is delimited by a tubular casing 6 developing according to the longitudinal direction X of the tubular jacket 2 is arranged in said tubular jacket 2.
The aforementioned tubular casing 6 is separated from the tubular jacket 2 by means of an interspace 9 and it is provided with a suctioning mouth 7, communicating with the inlet mouth 3 of the tubular jacket 2, and a delivery mouth 8, communicating with the interspace 9.
The pumping unit 5 is adapted to pump the liquid from the suctioning mouth 7 towards the delivery mouth 8 and thus from the inlet mouth 3 to the outlet mouth 4 of the tubular jacket 2.
The electric pump 1 further comprises sealing means 10 configured so as to prevent the liquid in the interspace 9 from flowing from the delivery mouth 8 towards the suctioning mouth 7.
Therefore, the aforementioned sealing means 10 prevent the pumped liquid from returning towards the suctioning mouth 7 due to the pressure difference, thus causing loss of efficiency of the electric pump 1.
According to the invention, the aforementioned sealing means 10 are arranged in the interspace 9, in intermediate position between the suctioning mouth 7 and the delivery mouth 8 of the tubular casing 6.
The arrangement of the sealing means 10 described above differs from that of the previously described electric pumps of the known type, wherein the sealing means are arranged at the suctioning mouth of the pumping unit.
It is observable that the sealing means 10 arranged as described above limit the width of the lower portion of the interspace 9 where the solid impurities of the pumped liquid may sediment.
Actually, the aforementioned impurities cannot drop below the sealing means 10 in any case.
Thus, the electric pump described above attains the object of limiting the formation of scales.
As a consequence, advantageously, the electric pump 1 is particularly suitable for pumping the liquids containing solid impurities.
Preferably, the sealing means 10 are arranged in proximity of the delivery mouth 8, so that the entire area of the interspace 9 communicating with the delivery mouth 8 and adjacent to the sealing means 10 is affected by the flow of the fluid exiting from the delivery mouth 8.
In this way, the aforementioned area of the interspace 9 adjacent to the sealing means 10 is washed by the liquid during the operating steps of the electric pump 1.
Thus, possible deposits of impurities that may form in such area during the previous stop step are removed by the flow of the liquid, thus preventing the formation of scales.
Preferably and as observable more in detail in fig. 2, the aforementioned sealing means 10 comprise an annular gasket 11, preferably of the "O-ring" type.
Even more preferably, the aforementioned annular gasket 11 is housed in an annular groove 12 defined on the outer surface of the tubular casing 6. Advantageously, the aforementioned annular groove 12 allows making the position of the annular gasket 11 stable.
Preferably, the tubular jacket 2 internally defines an annular recess 13 arranged in contact with said annular gasket 11.
Advantageously, the aforementioned annular recess 13 can be easily obtained by deep-drawing on the tubular jacket 2.
Preferably, the pumping unit 5 is constrained to the tubular jacket 2 by means of connection means 14 which connect each of the opposite ends 23, 24 of the tubular casing 6 to the tubular jacket 2 so as to prevent the displacement of the pumping unit 5 along the longitudinal direction X.
Preferably, the aforementioned connection means 14 are at least partly removable, so as to advantageously allow the slipping off of the pumping unit 5 from the tubular jacket 2 along said longitudinal direction X whenever there arises the need to perform the maintenance operations on the electric pump 1. Preferably, the aforementioned connection means 14 comprise two abutment rings 25, 26 arranged on the corresponding opposite ends 21, 22 of the tubular jacket 2, which are arranged in contact with the two opposite ends 23, 24 of the tubular casing 6.
Preferably, one of the two abutment rings 25 is rigid, while the other abutment ring 26 is adjustable, for example through screw means, so as to allow adjusting the axial constraint force to which the pumping unit 5 is subjected. Preferably, variant embodiments of the invention may provide for constraining the pumping unit 5 to the tubular jacket 2 by means of any other constraint means of the known type.
As regards the pumping unit 5, it comprises a pumping device 15 and a driving device 16 which actuates the pumping device 15, both being housed in the tubular casing 6.
The pumping device 15 comprises a mechanical sealing configured to prevent the pumped fluid from flowing towards the driving device 16.
Preferably, the pumping device 15 and the driving device 16 are mutually fixed, for example through screw means, so that they can be slipped off from the tubular jacket 2 as a single body.
Preferably, the driving device 16 comprises a shaft 17 with axis parallel to the aforementioned longitudinal direction X and a motor 18 which drives the shaft 17 in rotation and, preferably, it is electrical.
As regards the pumping device 15, preferably it comprises one or more rotors 19 fixed to said shaft 17.
Preferably, if the pumping device 15 comprises more than one rotor 19, it comprises a diffuser unit made up of a plurality of stages, each containing a respective rotor 19, stacked on each other according to the longitudinal direction X.
Each stage of the diffuser unit comprises a corresponding first cylindrical body, shaped so as to convey the fluid exiting from the respective rotor 19 towards the opening of the rotor 19 of the subsequent stage.
The delivery mouth 8 is obtained on a second cylindrical body, stacked on said diffuser unit, which preferably also serves as a support for the aforementioned mechanical sealing.
Advantageously, the aforementioned configuration is modular and thus allows obtaining different models of the electric pump, differing from each other due to the number of stages and thus the obtainable prevalence, using a limited number of different components.
In particular, the sealing means 10 are arranged between the aforementioned diffuser unit and the delivery mouth 8, so as to be in a position as close as possible to the latter.
Preferably, the sealing means 10 are associated to the outer surface of the aforementioned second cylindrical body.
Preferably, the pumping device 15 is interposed between the inlet mouth 3 of the tubular jacket 2 and the driving device 16, so as to be arranged at a high position during the operating step.
Advantageously, said arrangement allows arranging the inlet mouth 3 of the tubular jacket 2 directly facing the suctioning mouth 7 of the tubular casing 6, to the advantage of pumping efficiency.
In addition, said arrangement facilitates the electrical connection of the driving device 16.
As regards the delivery mouth 8 of the tubular casing 6, it preferably comprises a plurality of holes 20 arranged according to a ring orthogonal to the longitudinal direction X of the tubular jacket 2.
In addition, preferably, the inlet mouth 3 of the tubular jacket 2 is arranged at an end 21 of the tubular jacket 2.
The aforementioned configuration is particularly suitable for the use of the electric pump 1 in a well or for suction from a vat, in that it ensures that the inlet mouth 3 is arranged at the lowest point of the electric pump 1 and thus completely submerged in the liquid.
In the light of the above, it is observable that the electric pump of the invention attains the object of limiting, or even eliminating, the unwanted effects caused by the sedimentation of the solid impurities contained in the pumped liquid.
As a matter of fact, the particular position of the sealing means is such that the aforementioned impurities are mainly arranged along the path of the pumped liquid and, thus, they are removed from the flow of the liquid.
As a consequence, the formation of scales in the interspace is reduced or eliminated and thus the electric pump may be disassembled more easily with respect to the electric pumps of the known type, even after an extended period of operation.

Claims

Electric pump (1), of the type comprising:
- a tubular jacket (2) developing according to a longitudinal direction (X), provided with an inlet mouth (3) and an outlet mouth (4) for the passage of a liquid;

- a pumping unit (5) arranged in said tubular jacket (2), delimited by a tubular casing (6) developing according to said longitudinal direction (X) and which is separated from said tubular jacket (2) by means of an interspace (9), said tubular casing (6) being provided with a suctioning mouth (7) communicating with said inlet mouth (3) and a delivery mouth (8) communicating with said interspace (9), said pumping unit (5) being adapted to pump said liquid from said suctioning mouth (7) towards said delivery mouth (8);

- sealing means (10) configured so as to prevent said liquid from flowing along said interspace (9) from said delivery mouth (8) towards said suctioning mouth (7),
said sealing means (10) being arranged in said interspace (9), in intermediate position between said suctioning mouth (7) and said delivery mouth (8);
said pumping unit (5) comprising a pumping device (15) and a driving device (16) for the actuation of said pumping device (15), both arranged in said tubular casing (6);
said driving device (16) comprising a shaft (17) with axis parallel to said longitudinal direction (X) and a motor (18) for driving said shaft (17) in rotation; said pumping device (15) comprising a diffuser unit made up of a plurality of stages stacked on each other according to said longitudinal direction (X) and each containing a corresponding rotor (19) fixed to said shaft (17); characterised in that said sealing means (10) are arranged between said diffuser unit and said delivery mouth (8) according to said longitudinal direction (X).
Electric pump (1) according to claim 1, characterised in that said delivery mouth (8) is obtained on a cylindrical body stacked on said diffuser unit and in that said sealing means (10) are associated to the outer surface of said cylindrical body.
Electric pump (1) according to claim 2, characterised in that it comprises a mechanical sealing supported by said cylindrical body.
Electric pump (1) according to any one of the preceding claims, characterised in that said sealing means (10) are arranged in proximity of said delivery mouth (8) so that the entire area of said interspace (9) communicating with said delivery mouth (8) and adjacent to said sealing means (10) is affected by the flow of said fluid exiting from said delivery mouth (8).
Electric pump (1) according to claim 4, characterised in that said sealing means (10) comprise an annular gasket (11).
Electric pump (1) according to claim 5, characterised in that said tubular casing (6) externally defines an annular groove (12) adapted to house said annular gasket (11).
Electric pump (1) according to any one of claims 5 or 6, characterised in that said tubular jacket (2) internally defines an annular recess (13) arranged in contact with said annular gasket (11).
Electric pump (1) according to any one of the preceding claims, characterised in that it comprises connection means (14) for connecting each opposite end (23, 24) of said tubular casing (6) to said tubular jacket (2) so as to prevent the displacement of said pumping unit (5) along said longitudinal direction (X).
Electric pump (1) according to claim 8, characterised in that said connection means (14) are at least partly removable, so as to allow the slipping off of said pumping unit (5) from said tubular jacket (2) along said longitudinal direction (X).
Electric pump (1) according to any one of the preceding claims, characterised in that said driving device (16) comprises a shaft (17) having axis parallel to said longitudinal direction (X) and a motor (18) adapted to drive said shaft (17) in rotation, said pumping device (15) comprising one or more rotors (19) fixed to said shaft (17).
Electric pump (1) according to any one of the preceding claims, characterised in that said pumping device (15) is interposed between said inlet mouth (3) and said driving device (16).
Electric pump (1) according to any one of the preceding claims, characterised in that said delivery mouth (8) comprises a plurality of holes (20) arranged according to a ring orthogonal to said longitudinal direction (X).
Electric pump (1) according to any one of the preceding claims, characterised in that said inlet mouth (3) is arranged at an end (21) of said tubular jacket (2).