EP2921713B1

EP2921713B1 - Pump with a protection unit against water hammer

Info

Publication number: EP2921713B1
Application number: EP15159250.8A
Authority: EP
Inventors: Giuliano Matteazzi
Original assignee: Calpeda SpA
Current assignee: Calpeda SpA
Priority date: 2014-03-17
Filing date: 2015-03-16
Publication date: 2021-02-17
Anticipated expiration: 2035-03-16
Also published as: ES2867675T3; EP2921713A1; PL2921713T3

Description

The invention regards a pump with a protection unit against water hammer.
It is known that the term water hammer indicates a hydraulic phenomenon which is generated in a conduit traversed by a flowing liquid when the flow is suddenly interrupted by the sudden closure of a valve.
Similarly, water hammer also occurs when a valve present in the conduit is suddenly opened to create a liquid flow.
Substantially, water hammer consists in a pressure wave which is generated by the inertia of the fluid column flowing along the conduit when the flow, as mentioned, is suddenly interrupted or opened.
The maximum pressure value generated by the pressure wave can even reach very high levels and such to even seriously damage the conduits and the hydraulic apparatus that are upstream of the closed valve.
For example, in case of systems and hydraulic circuits in which there are hydraulic machines, for example pumps, the water hammer affects the pumping unit and can damage it, especially when the pumping unit is made of plastic material EP 2 366 906 A2 discloses a pump according to the preamble of claim 1.
Devices and systems are known for protecting systems, hydraulic circuits and hydraulic machines against water hammer which are mainly based on the use of deformable chambers, check valves or expansion chambers which absorb the pressure wave during the propagation thereof upstream of the area in which it was produced, preventing the energy thereof from propagating to the vital and weaker parts of the systems, hydraulic circuits and/or hydraulic machines.
Though being efficient, such devices reveal however the drawback of being rather expensive and they also often lead to an increase of the overall dimensions.
As a matter of fact, such devices are aggregated to the systems or hydraulic circuits or hydraulic machines and thus constitute elements which integrate them and which are also subjected to periodic maintenance and/or replacement operations.
The present invention aims at eliminating these drawbacks.
In particular, the first object of the invention is to provide a pump provided with a protection unit against water hammer arranged inside the pump and constituting a structural element of the pump.
Another object of the invention is to provide a pump with smaller overall dimensions with respect to the equivalent pumps without protection against water hammer.
Another object of the invention is to provide a pump with considerably lower production costs with respect to those of the equivalent pumps without protection against water hammer.
The aforementioned objects are attained by the pump of the invention whose characteristics are described in the appended claim 1.
Further characteristics of the invention are described in the dependent claims. Advantageously, given that in the pump of the invention the protection unit against water hammer is integrated in the structure of the pump, specific periodic maintenance is not required, excluding normal maintenance operations to which the pump should be subjected.
In addition, advantageously, the protection unit against water hammer that is the subject of the invention may be applied on a standard pump with the aim of modifying it and thus making it suitable to be protected against water hammer.
The aforementioned objects and advantages will be more apparent from the description of a preferred embodiment of the invention provided hereinafter, by way of non-limiting example, with reference to the attached drawings wherein:

fig. 1 represents the pump of the invention in longitudinal section;
figs. 2 to 5 represent details of the pump of fig. 1.

The pump of the invention is represented in longitudinal section in fig. 1 where it is indicated as a whole with 1.
It should be observed that the pump is of the submerged type, but generally the description outlined hereinafter may refer to a pump of any type.
It comprises a pump body 2 in which it is possible to identify a suctioning mouth 3 and a delivery mouth 4, the latter belonging to a delivery head 5 connected to the pump body 2, on the opposite side of the suctioning mouth 3 in this specific case.
A tubular jacket 7 is arranged inside the pump body 2 and it is configured to contain an electric motor 8 and a pumping unit 9 which are connected to each other through a transmission shaft 10.
A sealing unit 11 is arranged in a position substantially intermediate to the transmission shaft 10, and it is contained in the tubular jacket 7 as well and positioned between the electric motor 8 and the pumping unit 9.
In this way, in the tubular jacket 7 it is defined a motor housing 8a in which it is contained the electric motor 8 and a pumping housing 9a in which it is contained the entire pumping unit 9 including a rotor 9b and a distributor 9c.
A cover 12 is applied on the tubular jacket 7 and it is comprised between the delivery head 5 and the electric motor 8.
In addition, there is an annular body 13 which is comprised between the cover 12 and the delivery head 5 so as to delimit a delivery chamber 15 communicating with the delivery mouth 4.
Between the pump body 2 and the tubular jacket 7 it is defined a tubular interspace 14 which communicates with the pumping housing 9a through a plurality of first flow ways 16 which, as can be observed, are made according to an annular crown in the tubular jacket 7.
In addition, a plurality of second flow ways 17 are made in the annular body 13 and they are configured to place the delivery chamber 15 in communication with the tubular interspace 14.
When the electric motor 8 drives the rotor 9b of the pumping unit 9 in rotation, the fluid, in particular water or any other fluid which can be pumped, is suctioned through the suctioning mouth 3 and, after traversing the pumping unit 9 according to the longitudinal axis Y, reaches the tubular interspace 14 through the first flow ways 16 and thus, passing through the second flow ways 17 obtained in the annular body 13, reaches the delivery chamber 15 and the delivery mouth 4 to be conveyed in the distribution network.
According to the invention, in the annular body 13 there are first connection means 18 which are configured to axially constrain the annular body 13 and the cover 12 to each other and second connection means 19 which are configured to axially constrain the annular body 13 and the delivery head 5 to each other.
As regards the first connection means 18, it should be observed, with particular reference to figs. 2 and 3, that they comprise a first annular edge 20 which is projecting towards the inside of the annular body 13 and it is configured to be arranged to cover the corresponding perimeter edge 12a of the cover 12 arranged at the level of the tubular jacket 7.
In this way, due to the presence of the first annular edge 20 which projects towards the inside of the annular body 13, the latter encloses the cover 12 therein constraining it stably.
In addition, there is an annular channel 21 which is defined between the cover 12 and the tubular jacket 7 and it is configured to receive the first annular edge 20 after being arranged adhering and covering the corresponding perimeter edge 12a of the cover 12.
As regards the second connection means 19, they comprise a second annular edge 22 which is projecting towards the outside of the annular body 13 and it has a substantially U-shaped profile.
This U-shaped profile identifies a concavity 23 facing towards the tubular interspace 14 when the second annular edge 22 is comprised between the cover 12, the pump body 2 and the delivery head 5.
In addition, in the second annular edge 22 there are through holes 24 which are configured to receive means 25 for fixing the annular edge 22 to the delivery head 5.
More precisely, the second annular edge 22 comprises a first surface 26 placed against the lateral surface 12b of the cover 12 and a second surface 27, faced and substantially parallel to the first surface 26, welded in axial head contact with the pump body 2.
Lastly, a third surface 28 is comprised between the first surface 26 and the second surface 27 and it is substantially orthogonal to both.
In the third surface 28 there are the through holes 24 that are used to house the fixing means 25 of the annular edge 22 against the delivery head 5.
The delivery head 5 in turn comprises through counter holes 29 which are arranged coaxial to the through holes 24 obtained in the second annular edge 22 and they are configured to receive the fixing means 25.
The latter, in particular, comprise a plurality of screws 30 each of which comprises a manoeuvring head 30a facing towards the outside environment and placed in contact with the delivery head 5 and a threaded shank 30b arranged passing through the through holes 24 and the through counter holes 29 coaxial to each other.
In addition, there are a plurality of holder nuts 31 each of which is housed in the concavity 23 of the second annular edge 22 and receives the coupling of the threaded shank 30b of a corresponding screw 30.
Each holder nut 31 is stably sealingly fixed in the concavity 23, preferably but not exclusively by welding.
At the joining edges of the elements forming the pump and along which the hydraulic sealing is obtained, there are gaskets suitably shaped according to the prior art.
In particular, a gasket of the O-ring type 32 is interposed between the cover 12 and the tubular jacket 7, as observable in the figures.
Operatively, when the pump 1 is assembled, the fastening of the screws 30 causes the axial compression of the annular body 13 since it is fastened between the delivery head 5, the cover 12 and the tubular jacket 7.
Upon completion of the assembly, the annular body 13 is thus subjected to the two fastening forces Fs and F's equal and opposite to each other observable in fig. 4, which axially compress the annular body 13 according to the longitudinal axis direction Y.
The same compression forces also act on the pumping unit 9 and the tubular jacket 7, still as observable in fig. 4, while the pump body 2 is stretched by the same forces Fs and F's opposite to each other.
When a pressure wave caused by water hammer acts with a force Fa on the cover 12, as observable in fig. 5, the force Fa, through the first annular edge 20, is transmitted by the cover 12 and by the tubular jacket 7 to the annular body 13 while the reaction thereof F'a is transmitted by the fluid present in the pumping housing 9a to the sealing unit 11.
In this way, as observable, the annular body 13 is generally discharged.
Thus, advantageously, the thrust Fa due to the water hammer and the reaction thereof F'a do not act on the pumping unit 9, as it otherwise occurs in the embodiments of the know type, but on the annular body 13 which is discharged.
Thus, it is obtained the object of protecting the internal members of the pump and particularly the pumping unit 9 through a protection unit against water hammer, in this case constituted by the annular body 13, which is arranged inside the pump and constitutes a structural element of the pump itself.
In addition, it should be observed that the area of the pump comprised between the cover 12 and the sealing unit 11 is subjected to the compression forces Fa and F'a opposite to each other due to water hammer and the annular body 13 is thus substantially floating inside the pump body 2.
Simultaneously, the thrust Fa due to water hammer compresses the sealing ring 32 arranged between the cover 12 and the tubular jacket 7, and this facilitates hydraulic sealing.
According to the above, it is thus clear that the pump of the invention, provided with a protection unit against water hammer, attains all the preset objects.
First and foremost, it is obtained the main object of the invention which consists in providing a pump provided with a protection unit against water hammer arranged inside the pump and which constitutes a structural element of the pump itself.
As a matter of fact, the annular body 13, which constitutes the protection unit against water hammer, is constrained between the delivery head 5 and the cover 12 associated to the tubular chamber which contains the electric motor 8 and the pumping unit 9.
It is also obtained the object according to which the pump of the invention provided with a protection unit against water hammer substantially has the same overall dimensions as the equivalent pumps without protection against water hammer.
Indeed, it has been observed that the annular body 13 has a small axial overall dimension such not to considerably modify the overall dimension of the pump. In addition, the annular body 13 is not subjected to wear or deformations during use and thus it does not require neither to be replaced over time nor to undergo maintenance operations.
Thus, the pump of the invention only requires to receive standard maintenance operations to which all prior art pumps are subjected to.
In addition, in presence of water hammer, the entire thrust does not weigh on the pumping unit 9 but discharges on the annular body 13 which even improves the operating conditions thereof since it is discharged by the axial force through which it had been pre-compressed when mounting the pump. As a consequence, in presence of water hammer the structural static conditions of the pump are even improved.
It is also clear that the annular body 13 may provide for annular edges delimiting it to be variously configured, so as to be stably joined to the delivery head and the cover of the tubular jacket containing the pumping unit of pumps with shapes different from each other, provided the shapes conform to claim 1, so as to transform any standard operating pump into a pump of the invention configured with a protection unit against water hammer.
In the construction stage, the pump of the invention with a protection unit against water hammer as defined by claim 1 may be subjected to modifications not described and not represented herein.
However, it shall be observed that any modifications, should they fall within the scope of the claims below, shall be deemed all protected by the present patent.

Claims

Pump (1) comprising:
- a pump body (2) in which it is possible to identify a suctioning mouth (3) and a delivery mouth (4);

- a delivery head (5) connected to said pump body (2) and in which said delivery mouth (4) is obtained;

- a tubular jacket (7) arranged inside said pump body (2) and configured to contain an electric motor (8) and a pumping unit (9) connected through a transmission shaft (10);

- a sealing unit (11) arranged inside said tubular jacket (7) between said electric motor (8) and said pumping unit (9) to delimit a motor housing (8a) containing said electric motor (8) and a pumping housing (9a) containing said pumping unit (9);

- a cover (12) applied on said tubular jacket (7) and comprised between said delivery head (5) and said electric motor (8);

- an annular body (13) comprised between said cover (12) and said delivery head (5) to delimit a delivery chamber (15) communicating with said delivery mouth (4);

- a tubular interspace (14) defined between said pump body (2) and said tubular jacket (7);

- a plurality of first flow ways (16) made in said tubular jacket (7) and configured to place said pumping housing (9a) in communication with said tubular interspace (14);

- a plurality of second flow ways (17) made in said annular body (13) and configured to place said delivery chamber (15) in communication with said tubular interspace (14),
characterised in that in said annular body (13) there are:
- first connection means (18) configured to axially constrain said annular body (13) and said cover (12) to each other and comprising a first annular edge (20) projecting towards the inside of said annular body (13), said first annular edge being configured to be arranged to cover a corresponding perimeter edge (12a) of said cover (12) arranged at the level of said tubular jacket (7), and

- second connection means (19) configured to axially constrain said annular body (13) and said delivery head (5) to each other and comprising a second annular edge (22) projecting towards the outside of said annular body (13), said second annular edge (22) having a substantially U-shaped profile which identifies a concavity (23) facing towards said tubular interspace (14), said second annular edge (22) being comprised between said cover (12), said pump body (2) and said delivery head (5), said second annular edge (22) being provided with through holes (24) configured to receive means (25) for fixing said second annular edge (22) to said delivery head (5).
Pump (1) according to claim 1, characterised in that it comprises an annular channel (21) defined between said cover (12) and said tubular jacket (7) and configured to receive said first annular edge (20).
Pump (1) according to any one of the preceding claims, characterised in that said second annular edge (22) comprises:
- a first side (26) arranged against the lateral surface (12b) of said cover (12);

- a second side (27) faced and substantially parallel to said first side (26) welded in axial head contact with said pump body (2);

- a third side (28) comprised between said first side (26) and said second side (27) and substantially orthogonal to both, said third side (28) being provided with said through holes (24) to receive said means (25) for fixing said second annular edge (22) against said delivery head (5).
Pump (1) according to claim 3, characterised in that said delivery head (5) comprises through counter holes (29) coaxial to said through holes (24) and configured to receive said fixing means (25).
Pump (1) according to claim 4, characterised in that said fixing means (25) comprise:
- a plurality of screws (30) each of which comprises a manoeuvring head (30a) facing towards the outside and placed in contact with said delivery head (5) and a threaded shank (30b) arranged passing through said through holes (24) and said through counter holes (29);

- a plurality of holder nuts (31) each of which is housed in said concavity (23) of said second annular edge (22) and receives the coupling of the threaded shank (30b) of a corresponding screw (30).