Water storage tank and pump with said tank
Patent Information
- Authority / Receiving Office
- US · United States
- Patent Type
- Applications(United States)
- Current Assignee / Owner
- TREVITECH SRL
- Filing Date
- 2023-12-20
- Publication Date
- 2026-07-23
Smart Images
Figure US20260210094A1-D00000_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present invention relates to the field of hydraulic fluid management, and more in particular to a water storage tank to be used preferably, but not exclusively, with hydraulic pumps.
[0002] The invention also relates to a hydraulic pump with said water storage tank.BACKGROUND ART
[0003] “Pressure tank” hydraulic pumps, i.e., systems for increasing the pressure of drinking water with respect to the distribution network (or to a vessel), allowing the delivery of water to consumers at greater heights or far away, have been known for many years now.
[0004] A pressure tank system thus comprises a hydraulic pump, generally a centrifugal pump and, at the delivery end thereof, a water storage tank. A pressure switch that controls pump switch-on or switch-off at given delivery water pressures, or the pressure downstream of the pump, towards consumers, is also associated with the pump.
[0005] The storage tank is merely a vessel divided into two parts by membrane; the lower part of the vessel contains water at the delivery pressure of the pump, while the upper part contains air at a given pressure, which acts as elastic spring for the water on the delivery side. With the system at operating pressure, in the case of a small pressure drop detected by the pressure switch (for example caused by small leaks in the system or very brief use by a consumer) below a threshold value, the pump is operated to restore the delivery (or system) pressure to a pre-set optimal value (in practice, the operating pressure of the system), upon reaching which the pump is deactivated once again. This makes it possible to prevent continuous “starts and stops” of the pump for small pressure drops between the pre-set optimal value and the threshold value of the pressure at the delivery side of the pump.
[0006] When the pump is operating, to restore the pressure in the system (consumers closed), the membrane of the tank deforms, allowing expansion of the volume of the lower part of the vessel, filling it with water at the delivery pressure. When a small pressure drop occurs, the air acts as a spring, deforming the membrane in the opposite direction, or contracting the volume occupied by the water.
[0007] For larger calls for water by the consumer, for example managed by pressure switches, flow switches or pressure flow switches, or for more abrupt and larger pressure drops, the pump is operated until the consumers close.
[0008] A problem linked to known pumps with storage tank comprises the fact that the air chamber of the tank must be calibrated for each specific use in order to allow the correct operating range of the pump.
[0009] FIG. 1 shows a graph of the hydraulic head of the pump as a function of the flow rate, relating to the characteristic curve n of a pressure tank pump on which the storage tank is mounted. Take for example the case of a pump that requires to operate at around 4.5 bar (around 45 metres of hydraulic head). The storage tank of the pressure tank must operate, for example, in a pressure range between P1 equal to 3.5 bar (around 35 metres of hydraulic head) and P2 equal to 5.2 bar (around 52 metres of hydraulic head), where P1 is the pressure value below which the pressure switch of the pump activates rotation of the pump impeller and P2 is the operating pressure value of the storage tank, upon reaching which the pump stops pumping. After installing the pump, the installer must calibrate the amount of air in the tank between the membrane and the vessel, so that the latter can operate within this range.
[0010] As can be seen from the characteristic curve of FIG. 1, the pump can also operate for hydraulic head ranges other than the one indicated. Each time a pump is installed in a system, the installer must adjust the amount of air in the tank to allow the desired resistance of the membrane within the vessel. This adjustment inevitably lengthens the installation time of the pump.
[0011] Moreover, air can escape from in the vessel over time, decalibrating the operating range of the pump. Therefore, action must be taken at regular intervals to recalibrate the correct amount of air in the tank.
[0012] Furthermore, these vessels are oversized in order to withstand water hammering that occurs in the system.
[0013] Moreover, the water stored in these vessels tends not to drain completely, and therefore a certain amount of water remains in the vessel, creating possible problems of bacterial proliferation.
[0014] Not least, the use of these vessels also leads to system configurations that are usually very bulky.
[0015] To overcome these problems, the patent application EP4015826 describes a hydraulic pump provided with an integrated storage tank comprising a plurality of storage chambers, wherein each chamber has a storage volume that can expand based on the pressure value of the liquid stored and wherein each chamber is provided with an elastic spring device that contrasts expansion of the chamber. The stiffness of the springs in the chambers is different from chamber to chamber and therefore the chambers expand differently. For this reason, it is possible to use the pump in a variety of different work situations. In fact, each storage chamber, having its own expansion contrast device with its own stiffness, allows the pump to operate in a given range of pressures. In practice, the pump comprises storage tanks (chambers) already calibrated (during assembly, or design, of the pump) and therefore the pump merely requires to be positioned in the system without adjusting any element of the tank.
[0016] The solution described is particularly advantageous, but does not lend itself to possible improvements, in particular linked to the possibility of further reducing the size of the various components.SUMMARY
[0017] The aim of the present invention is therefore to provide a storage tank that can be integrated in a hydraulic pump and that can solve the problems linked to installation and use of the pump in systems to increase the pressure of drinking water with respect to the distribution network or to a vessel.
[0018] Within this aim, an important object of the present invention is to produce a storage tank that can be easily installed, for example in a pump for a system for increasing the pressure of the drinking water.
[0019] Another important object of the present invention is to produce a storage tank that makes regulation of the tank during installation unnecessary.
[0020] Another important object of the present invention is to produce a storage tank that makes it possible to limit maintenance of the pump.
[0021] Yet another important object of the present invention is to produce a storage tank that is particularly compact.
[0022] These and other objects, which will be more apparent below, are achieved with a water storage tank comprising at least one first and at least one second portion of storage chamber placed at the same pressure of the storage liquid and defining respective elastically variable storage volumes and wherein a first elastic contrast device to the expansion of the respective storage volume is associated with said first portion of storage chamber, and a second elastic contrast device to the expansion of the respective storage volume is associated with said second portion of storage chamber, whereby an increase in the pressure of the liquid in the tank corresponds to an expansion of the storage volumes overcoming the contrast of the respective elastic contrast devices, while a decrease in the pressure of the liquid in the tank corresponds to a contraction of said storage volume, and wherein each said elastic contrast device has a main direction of contrast to the expansion, wherein said two elastic contrast devices are arranged opposite each other, so that the respective main directions of contrast to the expansion have opposite directions. The fact that the water storage tank comprises at least one first and at least one second portion of storage chamber placed at the same pressure of a storage liquid, substantially means that the at least one first and at least one second portion of storage chamber are adapted to contain storage liquid and in these portions of chamber the liquid contained is at the same pressure.
[0023] According to one aspect, the invention relates to a water storage tank, comprising at least one first and at least one second storage chamber placed at the same pressure of a storage liquid and defining respective elastically variable storage volumes and wherein a first elastic contrast device to the expansion of the respective storage volume is associated with the first storage chamber, and a second elastic contrast device to the expansion of the respective storage volume is associated with the second storage chamber, whereby an increase in the pressure of the liquid in the tank corresponds to an expansion of the storage volumes overcoming the contrast of the respective elastic contrast devices, while a decrease in the pressure of the liquid in the tank corresponds to a contraction of said storage volume, and wherein each said elastic contrast device has a main direction of contrast to the expansion; the tank is characterized in that the two elastic contrast devices are arranged opposite each other, so that the respective main directions of contrast to the expansion have opposite directions. The fact that the first and the second chamber are placed at the same pressure of the storage liquid substantially means that this first and second storage chamber are adapted to contain a storage liquid and in these chambers the liquid contained is at the same pressure.
[0024] Preferably, the main directions of contrast to the expansion of the opposite elastic contrast devices substantially coincide in a single axis of action, with opposite directions.
[0025] According to preferred embodiments, the first contrast device associated with the first storage chamber is arranged at least partly within the second contrast device associated with the second storage chamber.
[0026] According to preferred embodiments, each elastic contrast device comprises
[0027] a movable element adapted to move, at least in part, from a first position corresponding to a minimum volume that can be occupied by the liquid in the chamber, to a second position corresponding to a maximum volume that can be occupied by the liquid in the chamber, and
[0028] an elastic contrast body adapted to generate an elastic contrast to the movement of the movable element from the first position to the second position
[0029] Preferably, the elastic contrast body is arranged externally to the storage chamber, between the movable element and an abutment stop, and is configured to compress in the direction from said movable element to said abutment stop.
[0030] According to preferred embodiments, the elastic contrast body of the first elastic contrast device associated with the first storage chamber is mainly arranged within the space occupied by the elastic contrast body of the second elastic contrast device associated with the second storage chamber; preferably, the elastic contrast bodies are axial springs, preferably helical, preferably cylindrical.
[0031] According to preferred embodiments, the movable element of the first elastic contrast device is adapted to slide within an axial channel defined within the movable element of the second elastic contrast device, or vice versa the movable element of the second elastic contrast device is adapted to slide within an axial channel defined within the movable element of the first elastic contrast device.
[0032] According to preferred embodiments, at least one movable element is integral with, or forms, a wall portion of a storage chamber, and the movement of at least part of the movable element allows expansion of the volume of the storage chamber; preferably, the movement direction of at least part of said movable element is coincident with the main direction of contrast to the expansion of the respective storage chamber.
[0033] According to preferred embodiments, each storage chamber has a first chamber part with a fixed volume and a second chamber part with a variable volume defined by the movement of the movable element of the respective elastic contrast device.
[0034] Preferably, the movable element comprises a membrane connected, with seal, to the first chamber part; preferably, a slider is fixed to this membrane, adapted to interact with the elastic contrast body to allow movement of part of the membrane in order to vary the volume of the chamber.
[0035] According to preferred embodiments, an outer casing defining a central housing is present, wherein respective closing lids are fixed to two opposite ends of said housing, whereby said first and said second storage chamber are defined at said closed ends, and wherein the first and the second elastic contrast devices are arranged in the central housing, adapted to act in contrast according to an opposite direction.
[0036] According to preferred embodiments, for each chamber the respective lid defines the first chamber part, and at least one passage is defined on the lid for entry and / or exit of the storage liquid and wherein the passages of the first and second chambers are at the same pressure.
[0037] Preferably the tank comprises a modular structure, provided with at least one module, wherein each module comprises one said central housing with two said storage chambers at the opposite ends, and wherein, in the case of at least two modules, the housings of said modules have respective central axes which are parallel and are placed side by side; preferably, adjacent storage chambers of two adjacent modules comprising the same lid.
[0038] According to preferred embodiments, for a given pressure value in the storage chambers, said at least one first elastic contrast device is associated with a first volume variation of at least one respective first storage chamber, and said at least one second elastic contrast device is associated with a second volume variation of said at least one respective second storage chamber, and wherein said first and second volume variations are different from each other, i.e. the at least one first elastic contrast device and the at least one second elastic contrast device are configured to allow different storage volumes for said at least one first and at least one second storage chamber; preferably, for a given pressure value, said elastic contrast devices are configured to allow different storage volumes in all the storage chambers.
[0039] According to preferred embodiments, at least two elastic contrast devices comprise a different elastic stiffness to each other.
[0040] According to preferred embodiments, the storage chambers all have the same minimum volume and maximum volume that can be occupied by the liquid.
[0041] According to preferred embodiments, the at least two storage chambers, and preferably all said storage chambers, have a first chamber part with a fixed volume and a second chamber part with a variable volume defined by the movement of said movable element, wherein the fixed volume of said first chamber part is the same for at least two said storage chambers, and wherein said at least two storage chambers are associated with elastic contrast bodies with different stiffnesses which allow different expansions of said chambers, whereby, with the same pressure of the liquid in the at least two said storage chambers, said chambers have different volumes.
[0042] According to another aspect, the invention relates to a hydraulic pump comprising a path for the liquid from at least one suction inlet of the liquid in the pump to a delivery outlet of the liquid from the pump and, along said path,
[0043] downstream of said inlet, a pressure section configured to increase the pressure of the liquid,
[0044] downstream of said pressure section, a storage tank for pressurized liquid according to one or more of the preceding claims,wherein said separate liquid storage chambers are all placed at the same liquid delivery pressure.
[0045] Preferably, the hydraulic pump comprises an outer casing within which said path for the liquid is defined, there being provided in said casing
[0046] a bay for containing at least one impeller of the pump,
[0047] a compartment for the liquid at the delivery pressure of the pump being configured on one side of said bay, so as to develop approximately following the development of the axis of rotation of said at least one impeller,and wherein said storage chambers of the tank are in direct communication with said compartment; preferably, the direction of action of said elastic contrast devices being orthogonal to the axis of the pump motor; preferably, a baseplate for the pump is provided on the opposite side of the bay, whereby said compartment is arranged above said bay; preferably, the delivery outlet of the liquid being provided on said compartment.
[0048] According to another aspect, the hydraulic pump is a submersible pump with axial development and at least one tank is arranged within the casing of the pump, with the axis of action of the elastic contrast devices that develops parallel to the axis of axial development of the submersible pump.
[0049] The hydraulic pump can comprise an electronic control device, operatively connected to which is an electric drive motor of the pressure member of the pressure section of the pump and a pressure gauge, preferably a pressure switch, adapted to gauge the pressure in the area between the delivery section and the delivery outlet of the liquid, whereby said electric motor is adapted to operate said pressure member upon reaching a first pressure value measured by said pressure gauge, and is adapted to interrupt the operation of said pressure member upon reaching a second pressure value measured by said pressure gauge, greater than said first value.BRIEF DESCRIPTION OF THE DRAWINGS
[0050] The invention will be better understood by following the description and the accompanying drawings, which illustrate some non-limiting examples of embodiment of the invention. More in particular, in the drawing:
[0051] FIG. 1 shows a hydraulic head / flow rate graph with characteristic curve of a generic hydraulic pump with expansion tank according to the prior art in which the pressure range within which the pump operates is highlighted;
[0052] FIG. 2 represents a schematic view of a pump according to the invention, sectioned along a longitudinal axis;
[0053] FIG. 3 represents a top view of the pump of FIG. 2, in which the storage tank is sectioned along a horizontal plane passing through the axis of tank;
[0054] FIG. 4 represents a schematic axial sectional view of the tank of FIG. 3 according to the invention;
[0055] FIG. 5 represents a schematic view of a variant of pump, with a tank equipped with two modules according to the invention, sectioned along a horizontal axis passing through the axes of the two modules;
[0056] FIG. 6 represents a top view of a variant of pump according to the invention, in which the storage tank, varied with respect to the examples of the preceding figures, is sectioned along a horizontal plane passing through the axis of the tank, with the tank in the phase of minimum, or no, expansion;
[0057] FIG. 7 represents the tank of FIG. 6, sectioned along a horizontal plane passing through the axis of the tank with the tank in the phase of maximum expansion;
[0058] FIG. 8 shows a hydraulic head / flow rate graph with characteristic curve of a hydraulic pump according to the invention;
[0059] FIG. 9 represents a schematic view of a submersible pump with axial development containing a tank according to the invention.DETAILED DESCRIPTION OF EMBODIMENTS
[0060] With reference to the aforesaid figures, a hydraulic pump with tank according to the invention is indicated as a whole with the number 100.
[0061] This pump 100 comprises an outer casing 101 on which the suction inlet 102 of the liquid in the pump, and the delivery outlet 103 of the liquid from the pump are defined.
[0062] Within the casing 101 a path P is provided for the liquid, which stretches from the suction inlet 102 to the delivery outlet 103 (schematized by dashed lines in FIG. 2).
[0063] Along the path P, within the casing, downstream of the suction inlet 102A, a pressure section 104 is present, configured to increase the pressure of the liquid. Therefore, the pump comprises, in succession, a suction section, in which the inlet 102, is present, the pressure section 104, and the delivery section in which the outlet 103 is present.
[0064] In particular, in this example, the pump is a multistage centrifugal pump (in other examples the pump can be single stage or not of centrifugal type) and therefore the pressure section 104 has a plurality of impellers, indicated as a whole with 105, mounted on a shaft with axis of rotation X.
[0065] More in particular, the casing 11 comprises a first bay 106, wherein the impellers 105 are arranged, and a second bay 107, in succession with respect to the first bay 106 along the axis X, wherein an electric motor 108 is provided to rotate the impellers 105.
[0066] On an outer side of the casing 101, a baseplate 101.1 is provided for the pump, so that the latter preferably operates with the axis of rotation X parallel (or almost parallel) to the surface on which the baseplate of the pump rests. The pump can also operate arranged on a supporting surface so that its axis X is orthogonal, or almost orthogonal, to this surface, in practice being able to operate with any positioning in space.
[0067] Along the path P, downstream of the pressure section 104 (and naturally upstream of the delivery outlet 103), a compartment 109 is present wherein the liquid is substantially at the same pressure as the outlet 103, or the delivery pressure.
[0068] In particular, for example, this compartment 109 is provided on a side of the first bay 106 opposite the side of said first bay on which the baseplate 101.1 is provided, so that the compartment 109 is arranged above the first bay 106.
[0069] It should be noted that this compartment 109 has, for example, a greater longitudinal development so as to follow the development of the axis of rotation X of the impellers. In other embodiments, the compartment 109 can be replaced by one or more channels, all at the same delivery pressure as the outlet 103.
[0070] Along the path P, downstream of the pressure section 104, a storage tank 10 of pressurized liquid is also present, which has an elastically variable storage volume and an elastic contrast system to the expansion of the storage volume when the pressure in the tank increases.
[0071] Advantageously, this storage tank 10 has, for example, a modular structure, wherein each module M has a first and a second portion of liquid storage chamber which, in this embodiment, consist of two distinct opposite liquid storage chambers 20 and 30. FIGS. 2 and 3 show the case of a single module M. FIG. 5 shows the case of two modules side by side, for a total of four storage chambers. FIGS. 6 and 7 show a second embodiment, wherein each module has a single storage chamber formed by a first and a second portion of storage chamber, opposite each other, as better explained below.
[0072] Returning to the case of FIGS. 2 to 5, the storage chambers 20 and 30 are all placed at the same pressure of the storage liquid corresponding to the delivery pressure of the pump 100 (this applies both to the case of a single module M with two chambers, and to the case of several modules M with multiples of two chambers).
[0073] Each storage chamber 20, 30 defines a respective elastically variable storage volume and is associated with a respective elastic contrast device to the expansion of the respective storage volume.
[0074] In particular, a first elastic contrast device 21 to the expansion of the respective storage volume is associated with the first storage chamber 20, and a second elastic contrast device 31 to the expansion of the respective storage volume, which is arranged opposite the first elastic contrast device 21, is associated with the second storage chamber 30.
[0075] Advantageously, the first and the second elastic contrast device 21, 31 have coincident main directions of contrast that lie on the same axis of action K, but have opposite directions of contrast. Preferably, the direction coincident with the axis of action K is orthogonal to the axis of rotation X of the impellers that forms the pressure section 104 of the pump.
[0076] In practice, the expansions (directions of expansion indicated by the arrows h1 and h2 respectively, in FIG. 3) of the two chambers 20 and 30 are directed toward each other and the directions of contrast to the expansion are opposite each other.
[0077] From a practical point of view, an increase in the pressure of the liquid in the tank corresponds to an expansion of the storage volumes of both the first and the second chamber 20, 30, overcoming the contrast of the respective elastic contrast devices 21, 31, while a decrease in the pressure of the liquid in the tank corresponds to a contraction of the storage volumes.
[0078] Each elastic contrast device is independent and autonomous with respect to the other elastic contrast devices, or is able to contrast the expansion of the volume only of the chamber with which it is associated.
[0079] Advantageously, the first contrast device 21 associated with the first storage chamber 20 is arranged at least partly within the second contrast device 31 associated with the second storage chamber 30, as better described below.
[0080] For example, each module of the storage tank 10 comprises an outer casing 40, defining a central housing 41, for example at least partly cylindrical, and wherein a first membrane 22 and a second membrane 32 and, respectively, a first closing lid 23 and a second closing lid 33 are fixed at two opposite ends of the central housing 41. The central portions of the membranes are movable in the direction of the axis K, as better explained below. The spaces between the membranes 22,32 and the respective lid 23,33 define the first and the second storage chamber 20, 30. The membranes are deformable and made, for example, of rubber, for example of EPDM.
[0081] In practice, each storage chamber 20, 30 has a first chamber part 20.1, 30.1 with a fixed volume (the part near to the respective closing lid, which corresponds to the minimum volume that can be occupied by the liquid, or when there is no expansion of the chamber by the liquid, as shown in FIG. 4) and a second chamber part with a variable volume 20.2, 30.2 defined by the movement of the membrane (whose maximum size is determined by the maximum amount of liquid that can be housed in the chamber, or the maximum expansion of the chamber, as shown in FIG. 3).
[0082] In these examples, each membrane 22, 32 is connected, with hydraulic seal, along its edge, between the respective closing lid 23, 33 and the end of the casing 40.
[0083] The first elastic contrast device 21 comprises a first movable element 24 adapted to move from a first position corresponding to a minimum volume that can be occupied by the liquid in the first storage chamber 20 (and corresponding to the fixed part of storage chamber, FIG. 4), to a second position corresponding to a maximum volume that can be occupied by the liquid in the storage chamber 20 (i.e., to the maximum volume of the second chamber part with a variable volume, FIG. 3), and a first elastic contrast body 25 adapted to generate an elastic contrast to the movement of the movable element 24 from the first position to the second position.
[0084] The first movable element 24 has a fixing assembly 24.1 to the first membrane 22 and a first rod 24.2 integral with the first fixing assembly 24.1, adapted to translate along the movement direction coincident with the axis of action K (the axis of the rod coincides with the axis K), so that the movement of the first rod 24.2 causes the movement of the first fixing assembly 24.1 and consequently of the portion of the first membrane 22 in the movement direction, thereby allowing the volume variation of the first storage chamber 20.
[0085] The first fixing assembly 24.1 comprises, for example, two discs fixed on the first rod 24.2 which block a portion 22.1 of membrane 22 in the manner of a sandwich. A first disc is provided within the chamber 20, while the second disc is provided externally to the chamber 20. Naturally, the membrane can be connected to the rod in a different way, in the most convenient manner.
[0086] In practice, the first movable element 24 comprises the first membrane 22 which is connected, with seal, to the first lid (in practice the first chamber part) of the first chamber and a slider (the two discs fixed to the first rod) is fixed to said membrane 22, adapted to interact with the elastic contrast body 25 to allow movement of part of the membrane in order to vary the volume of the chamber.
[0087] As said, the first elastic contrast device 21 comprises a first elastic contrast body 25 adapted to generate an elastic contrast to the movement of the first rod 24.2, or of the first fixing assembly 24.1, i.e., of the first membrane 22 from the first position to the second position.
[0088] In practice, the first movable element comprises the first membrane 22 which is connected, with seal, to the first chamber part and a slider (the two discs fixed to the first rod) is fixed to this membrane 22, adapted to interact with the elastic contrast body 25 to allow movement of part of the membrane in order to vary the volume of the chamber.
[0089] Toward the end of the central housing 41 corresponding to the first chamber 20, said housing is closed by a dividing body 42, the which has a bowl portion 43 developing within the housing 41 toward the second chamber 30. This bowl portion 43 is open toward the first chamber 20 and has a bottom 44. The length of this bowl portion is such as to reach with its bottom 44 preferably an intermediate axial position of the central housing 41. The first elastic contrast device 21 is arranged, at least in part, within the space defined by the bowl portion 43.
[0090] In practice, the first elastic contrast body 25 is arranged between the bottom 44 of the bowl portion 43 and the second disc of the first fixing assembly 24.1. The first rod 24.2 is adapted to translate at least in part within the bowl portion 43.
[0091] In this example, the first elastic contrast body 25 is a cylindrical helical spring which rests with one end thereof on the bottom of the bowl portion 43 and which surrounds the first rod 24.2 (the rod is inserted into the cylindrical space of the spring); preferably, the axis of the spring and the axis of the rod are coincident with each other and with the axis K.
[0092] It is clear that in other embodiments the first elastic contrast body (and also the second elastic body which will be described below) can also be formed by elements other than helical springs, for example by elastic elements of different shape, or also by elastomeric elements, or by gas springs, etc.
[0093] In general, in the present invention, the term “elastic” is meant as a component that, if stressed in one direction, tends to become deformed and, when no longer stressed, the component returns to the initial configuration. Therefore, the term elastic can mean purely elastic, quasi-elastic, viscoelastic, nonlinear elastic behaviours, etc.
[0094] Preferably, the dividing body 42 produces a limit stop for the first movable element 24, for example defining an abutment for the second disc of the first fixing assembly 24.1 (corresponding to the maximum volume of the first storage chamber 20).
[0095] Similarly to the case of the first elastic contrast device 21, the second elastic contrast device 31 comprises a second movable element 34 adapted to move from a first position corresponding to a minimum volume that can be occupied by the liquid in the second storage chamber 30 (and corresponding to the fixed part of storage chamber, FIG. 4), to a second position corresponding to a maximum volume that can be occupied by the liquid in the second storage chamber 30 (i.e., to the maximum volume of the second part of chamber with a variable volume, FIG. 3), and a second elastic contrast body 35 adapted to generate an elastic contrast to the movement of the second movable element 34 from the first position to the second position.
[0096] Similarly to the first movable element, the second movable element 34 has a second fixing assembly 34.1 to the second membrane 32 and a second rod 34.2 integral with the second fixing assembly 34.1 (rod and fixing assembly are not hatched, for graphic clarity), adapted to translate along the movement direction coincident with the axis of action K (the axis of the rod coincides with the axis K), so that the movement of the second rod 34.2 causes the movement of the second fixing assembly 34.1 and hence of the portion of second membrane 32 in the movement direction, thereby allowing the volume variation of the second storage chamber 30.
[0097] Similarly to the first assembly, the second fixing assembly 34.1 comprises, for example, two discs fixed on the second rod 34.2 which block a portion 32.1 of membrane 32 in the manner of a sandwich. A first disc is provided within the second chamber 30, while the second disc is provided externally to this chamber. Naturally, the membrane can be connected to the rod in a different way, in the most convenient manner.
[0098] As said, the second elastic contrast device 31 comprises a second elastic contrast body 35 adapted to generate an elastic contrast to the movement of the second rod 34.2, or of the second fixing assembly 34.1, i.e., of the second membrane 32 from the first position to the second position.
[0099] In practice, the second movable element comprises the second membrane 32 which is connected, with seal, to the first chamber part and a slider (the two discs fixed to the second rod) is fixed to this membrane 32, adapted to interact with the second elastic contrast body 35 to allow movement of part of the membrane in order to vary the volume of the chamber.
[0100] The second elastic contrast body 35, for example a cylindrical helical spring, rests with one end thereof against the dividing body 42 of the housing 41, surrounding the bowl portion 43 and the opposite end is in contact with the second disc of the second fixing assembly 34.1.
[0101] The part of the bottom 44 of the bowl portion 43 that faces the second chamber 30 acts as limit stop for the second movable element 34. It should be noted that in this example, the movable element 34 also comprises a spacer bushing 34.3, for example fixed at the second disc of the second fixing assembly 34.1 and which surrounds the second rod 34.2.
[0102] A guide system along the axis K is associated with the first and with the second movable element 24, 34. For example, this guide system comprises a hole 45, passing through the bottom 44 of the bowl portion 43 and coaxial to the axis K. The wall of this hole 45 guides, for example, the outside of the second rod 34.2 along the direction defined by the axis K, so that the rod enters the bowl portion 43, within the space delimited by the first spring 25.
[0103] In this example, the second rod 34.2 is axially hollow and open at one end, thereby defining an axial channel 34.4 within which the first rod 24.2 is arranged slidingly, so that this first rod is guided within the second rod.
[0104] It is understood that in other examples the first rod 24.2 could have a larger diameter than the second rod 34.2, and be axially hollow to define a channel for sliding and guiding of the second rod 34.2, with the hole 45 that directly guides the first rod 24.2.
[0105] A damping element 46, such as a pair of opposite Belleville washers that surround the second rod 24.2, which can also be useful to eliminate water hammering, can be present on the part of the bottom 44 of the bowl portion 43 that acts as limit stop for the second movable element 34.
[0106] The elastic contrast bodies 25, 35 are arranged externally to the respective storage chambers on which they act, between the movable elements 24, 34 and the respective abutment stops 42, 44, and are configured to compress in the direction from the respective movable elements to said abutment stops.
[0107] It should be noted that the first elastic contrast body 25 of the first elastic contrast device 21 associated with the first storage chamber 20 is arranged mainly within the space of the second elastic contrast body 35 of the second elastic contrast device 31 associated with the second storage chamber 30.
[0108] It should be noted that the movable elements 24, 34 can be integral with, or form, a respective portion of the wall of a respective storage chamber 20, 30, and the movement of at least part of the respective movable element 24, 34 allows expansion of the volume of the storage chamber.
[0109] Each chamber 20, 30 has at least one passage 27, 37 for entry and, preferably, for exit of the liquid into / from the chamber. Preferably, said passage is provided on the closing lid 23, 33.
[0110] These passages 27, 37 are operatively connected through respective ducts 47, with the compartment of the pump 109, wherein the liquid is substantially at the same pressure as the outlet 103, or the delivery pressure of the pump.
[0111] In preferred examples, the storage chambers present in the tank 10 are substantially the same, or all have the same (minimum and maximum) volume, therefore, what makes expansion of the chambers 20, 30 differ is the different stiffness value of the elastic contrast bodies 25, 35.
[0112] It is understood that in other embodiments, the stiffness of the two springs can be the same and expansion of the two chambers, i.e., the volume variation therein, can be the same (in practice, as if there were a single expansion chamber divided into two opposite sub-chambers).
[0113] For one module, for a given pressure value in the storage chambers 20, 30, a first volume variation of the first storage chamber 20 is associated with the first elastic contrast device and a second volume variation of the second storage chamber is associated with the second elastic contrast device, which differs from the first variation (the first elastic contrast device and the second elastic contrast device are configured to allow different storage volumes for the two storage chambers). In general, with several modules, it is preferable that for a given pressure value of the liquid, the elastic contrast devices are configured to allow different storage volumes in all the storage chambers.
[0114] The pump 100 further comprises an electronic control device 140 (for example, placed inside a box body 140A), to which the electric drive motor 108 of the impellers 105 is operatively connected, and a pressure gauge 141, preferably a pressure switch, adapted to gauge the pressure in the area between the delivery outlet 103 and the pressure section outlet, i.e., adapted to gauge the pressure in the delivery section of the pump downstream of the impellers (or the pressure gauge can be arranged downstream of the outlet 103), whereby the electric motor 108 is adapted to rotate the impellers upon reaching a first pressure value measured by the pressure switch 141, and is adapted to interrupt operation of the impellers upon reaching a second pressure value also measured by the pressure switch, greater than the first value, as better explained below.
[0115] When the pump is operating causing an increase in the pressure of the liquid to the delivery of the pump, this pressure increase also occurs in the storage chambers 20, 30 (they are all at the same pressure) which start to fill to a greater extent within the second chamber part 22.2, 32.2 deforming the membrane 22, 32 (expanding the volume of the chambers) and overcoming the elastic resistance of the springs 23, 33, which are compressed. On the contrary, a decrease in the pressure of the liquid at the delivery side of the pump, or in the storage chambers 20, 30, corresponds to a contraction of the storage volume previously subjected to expansion in the chamber 20, 30, or the membrane 22, 23 thrust by the spring 23, 33, returns toward the first chamber part 20.1, 30.1.
[0116] FIG. 5 shows the case of two modules, in which four chambers are present, respectively two first chambers 20 and two second chambers 30. In some examples of several modules M side by side, the closing lids 22 and 23 can be common for respective adjacent first chambers and adjacent second chambers.
[0117] Advantageously, the four elastic contrast bodies / springs associated with the four chambers all have different elastic stiffnesses. For example, a first elastic contrast body has an elastic stiffness K1, a second elastic contrast body has an elastic stiffness K2, with K2>K1, a third elastic contrast body has an elastic stiffness K3, with K3>K2, and a fourth elastic contrast body has an elastic stiffness K4, with K4>K3.
[0118] The storage chambers are substantially the same as each other, and in particular the membranes 23, 33 all have the same surface. Therefore, with the same increase in pressure in the storage chambers 20, 30 (they are always all at the same pressure) the expansion of their volume is differentiated based on the stiffness of the springs 23, 33. More in particular, the expansion in the chambers will be increasing as a function of the stiffness of the springs associated with the movement of the relative membrane (the greater the stiffness of the spring of the elastic contrast device, the smaller the movement of the movable element associated with the membrane, or the smaller the volume variation, or expansion of the chamber). The same arrangement of four expansible storage chambers with which four springs with different stiffnesses that contrast expansion of the chambers are associated is, for example, described in EP4015826. The same description of the general operation is integrated herein by incorporation.
[0119] The fact of having storage chambers that expand in a differentiated way makes it possible to use the pump in many different operating situations. In fact, each storage chamber, having its own contrast device to the expansion with its own stiffness, allows the pump to operate in a given range of pressures. In practice, the pump comprises storage tanks (chambers) already calibrated (during assembly, or design, of the pump) and therefore it is sufficient to position the pump in the system without regulating any element of the tank.
[0120] In fact, a first chamber can expand, for example, to a value Pa, value whereby the movable element of a first elastic contrast device reaches its limit stop (the membrane expands the chamber to its maximum and the first spring is compressed by a value W1). A second chamber can, for example, expand to a value Pb>Pa, value whereby the movable element of the second elastic contrast device reaches its limit stop (the membrane expands the second chamber to its maximum and the second spring is compressed by a value Wb<Wa). A third chamber can, for example, expand to a value Pc>Pb, value whereby the movable element of the third elastic contrast device reaches its limit stop (the membrane expands the third chamber to its maximum and the third spring is compressed by a value Wc<Wb). The fourth chamber can, for example, expand to a value Pd>Pc, value whereby the movable element of the fourth elastic contrast device reaches its limit stop (the membrane expands the fourth chamber to its maximum and the fourth spring is compressed by a value Wd<Wc).
[0121] The graph of FIG. 8 shows the hydraulic head / flow rate graph with the operating curve n of the pump. The graph highlights the four operating ranges of the pump Po-Pa-Pb-Pc-Pd (the limits of each range coincide with the lower and upper limits of the operating pressure of the tank in this range) linked to the stiffness of the springs of the four contrast devices, or to the different expansion capacities of the four storage chambers.
[0122] For example, if the pump requires to operate in a pressure range between the ambient pressure Po (for example, the pump draws water from a vessel that is not pressurized) and a hydraulic head value Pa of around 22 metres (equal to an increase of around 2.2 bar), once the pump has been connected to the system, with the system closed, the pump is operated, thereby pressurizing the system and the storage chambers to the pressure Pa. All four chambers are filled with liquid and all expand as a function of their expansion capacity, i.e., the first storage chamber expands to a greater degree than the second chamber, which expands to a greater degree than the third chamber, which expands to a greater degree than the fourth chamber.
[0123] A pressure drop at the delivery side of the pump generates a contraction of the volume in the storage chambers. If the pressure drops below the required threshold, the pump pressurizes the tank again, delivering new water to the storage chambers until reaching the operating pressure Pa of the tank.
[0124] If the same pump as the example cited above is installed in a system with an operating range, for example, between the hydraulic head values equal to Pb=35 m and Pc=52 m (around 3.5 bar and 5.2 bar), it is noted how no regulation of the storage tank is required. In fact, when the pump fills all the chambers 20 with water to the pressure Pb, upon reaching a first value Pa, the first storage chamber expands completely. The pressure continues to increase and upon reaching Pb, the second storage chamber expands completely. The pressure increases again and upon reaching Pc, or the maximum operating pressure, the third storage chamber expands substantially completely (or also not completely, depending on how the spring is configured). Upon reaching this pressure, the pump stops pumping. In the fourth chamber the membrane expands its volume by a fraction of its permissible volume, or the spring associated therewith is compressed by a value Wd′<Wd.
[0125] It should be noted that the remaining expansibility of the fourth chamber can be used to offset any pressure peaks caused by water hammering (naturally the fourth spring must be sized in terms of stiffness to allow these peaks to be absorbed).
[0126] It should be noted how the concept of different expansion capacity, as well as with different stiffnesses of the elastic contrast elements associated with the chambers, can be used in a system that has the same stiffness, but different sizes (in terms of surface area) of the membrane in the chambers. In fact, with the same pressure, by increasing the area of the membrane, the elastic contrast force increases. Therefore, two chambers with membranes of different sizes, but associated with elastic contrast springs with the same stiffness, have a different expansion volume variation.
[0127] Compared to the case described in EP4015826, the solution according to the present invention has a particularly compact tank, as by using two elastic contrast devices arranged opposite each other, so that the respective main directions of contrast to the expansion have opposite directions, it is possible to position the expansion chambers axially in front of each other, optionally with part of the operating structure of a chamber within the operating structure of the other chamber, optimizing the spaces. In particular, the case in which the springs are placed one inside the other ensures a very compact distribution of the overall dimensions.
[0128] Being very compact, the tank thus structured can be used in many pump varieties.
[0129] As said, FIGS. 6 and 7 show a second embodiment of a tank module, indicated as a whole with 110. In this situation, the storage tank 110 comprises a single storage chamber A formed by a first portion of storage chamber 120, and a second portion of storage chamber 130. Each portion of storage chamber 120, 130 defines a respective elastically variable storage volume and is associated with a respective elastic contrast device to the expansion of the respective storage volume.
[0130] In particular, a first elastic contrast device 121 to the expansion of the respective storage volume is associated with the first portion of storage chamber 120, and a second elastic contrast device 131 to the expansion of the respective storage volume, which is arranged opposite the first contrast device 121, is associated with the second portion of storage chamber 130.
[0131] Advantageously, the first and the second elastic contrast device 121, 131 have coincident main directions of contrast that lie on the same axis of action K, but have opposite directions of contrast, similarly to the previous embodiment.
[0132] In practice, the expansions (directions of expansion indicated by the arrows h1′ and h2′ in FIG. 7) of the two chambers 20 and 30 are directed in opposite directions and the directions of contrast to the expansions are instead directed toward each other.
[0133] From a practical viewpoint, an increase in the pressure of the liquid in the tank corresponds to an expansion of the storage volumes of both the first and the second portion of chamber 120, 130, overcoming the contrast of the respective elastic contrast devices 121, 131, while a decrease in the pressure of the liquid in the tank corresponds to a contraction of the storage volumes.
[0134] Each elastic contrast device is independent and autonomous with respect to the other elastic contrast devices, or it is capable of contrasting the expansion of the volume only of the portion of chamber with which it is associated.
[0135] For example, each module of the storage tank 110 comprises an outer casing 140, defining a central housing 141, for example at least partly cylindrical, and wherein a first membrane 122 and a second membrane 132, respectively, and a first closing dome 123 and a second closing dome 133, respectively, are fixed at two opposite ends of the central housing 141. The central portions of the membranes are movable in the direction of the axis K, as better explained below. The spaces between the membranes 122,132 and a centreline plane W of the central housing 141 define the first and the second portion of storage chamber 120, 130. The membranes are deformable and made, for example, of rubber, for example of EPDM, as in the previous embodiment.
[0136] In practice, each portion of storage chamber 120, 130 has a first part 120.1, 130.1 of chamber portion with a fixed volume (the part near to the respective closing dome, which corresponds to the minimum volume that can be occupied by the liquid, i.e. when there is no expansion of the portion of chamber by the liquid, as shown in FIG. 6) and a second part of chamber with a variable volume 120.2, 130.2 defined by the movement of the membrane (the maximum size of which is determined by the maximum amount of liquid that can be housed in the portion of chamber, or the maximum expansion of the portion of chamber, as shown in FIG. 7).
[0137] In these examples, each membrane 122, 132 is connected, with hydraulic seal, along its edge, between the respective closing dome 123, 133 and the end of the casing 140, or the end of the central housing 141.
[0138] The first elastic contrast device 121 comprises a first movable element 124 adapted to move from a first position corresponding to a minimum volume that can be occupied by the liquid in the first portion of storage chamber 120 (and corresponding to the fixed part of portion of storage chamber, FIG. 6), to a second position corresponding to a maximum volume that can be occupied by the liquid in the portion of storage chamber 120 (i.e., to the maximum volume of the second portion of chamber part with a variable volume, FIG. 7), and a first elastic contrast body 125 adapted to generate an elastic contrast to the movement of the movable element 124 from the first position to the second position.
[0139] The first movable element 124 has a fixing assembly 124.1 to the first membrane 122 and comprises for example, two discs which block a portion 122.1 of membrane 122 in the manner of a sandwich. A first disc is provided within the first portion of chamber 120, while the second disc is provided externally to the portion of chamber 120. Naturally, the membrane can be connected to the rod in a different way, in the most convenient manner.
[0140] A first rod 124.2 is integral with the first fixing assembly 124.1, for example with the first disc. This first rod is adapted to translate along the movement direction coincident with the axis of action K (the axis of the rod coincides with the axis K). The movement of the first rod 124.2 corresponds to the movement of the first fixing assembly 124.1 (and vice versa) and hence of the portion of first membrane 122 in the movement direction, thereby allowing the volume variation of the first portion of storage chamber 120.
[0141] In practice, the first movable element 124 comprises the first membrane 122 which is connected, with seal, to the first closing dome (in practice, the first part of chamber portion) of the first portion of chamber and a slider (the two discs fixed to the second rod) is fixed to this membrane 122, adapted to interact with the elastic contrast body 125 to allow movement of part of the membrane in order to vary the volume of the portion of chamber.
[0142] In practice, the first elastic contrast body 125 is arranged between the bottom 123.1 of the dome 123, which forms an abutment stop for this first elastic contrast body 125, and an abutment on the second disc of the first fixing assembly 124.1. Preferably, a sleeve 123.2 which is surrounded by the elastic contrast body 125, develops from the bottom 123.1.
[0143] In this example, the first elastic contrast body 25 is a cylindrical helical spring that rests with one end thereof on the bottom of the dome 123 and which surrounds a sleeve 123.2 that develops from the bottom 123.1 of the dome 123.
[0144] It is clear that in other embodiments, the first elastic contrast body (and also the second elastic body which will be described below) can also be formed by elements other than helical springs, for example by elastic elements of different shape, or also by elastomeric elements, or by gas springs, etc.
[0145] In general, in the present invention, the term “elastic” is meant as a component that, if stressed in one direction, tends to become deformed and, when no longer stressed, the component returns to the initial configuration. Therefore, the term elastic can mean purely elastic, quasi-elastic, viscoelastic, nonlinear elastic behaviours, etc.
[0146] Similarly to the case of the first elastic contrast device 121, the second elastic contrast device 131 comprises a second movable element 134 adapted to move from a first position corresponding to a minimum volume that can be occupied by the liquid in the second portion of storage chamber 130 (and corresponding to the fixed part of portion of storage chamber, FIG. 6), to a second position corresponding to a maximum volume that can be occupied by the liquid in the second portion of storage chamber 130 (i.e., to the maximum volume of the second portion of chamber part with a variable volume, FIG. 7), and a second elastic contrast body 135 adapted to generate an elastic contrast to the movement of the second movable element 134 from the first position to the second position.
[0147] The second movable element 134 has a second fixing assembly 134.1 to the first membrane 132 and comprises, for example, two discs which block a portion 132.1 of membrane 132 in the manner of a sandwich. A first disc is provided within the second portion of chamber 130, while the second disc is provided externally to the portion of chamber 130. Naturally, the membrane can be connected to the rod in a different way, in the most convenient manner.
[0148] A second rod 134.2 is integral with the first fixing assembly 134.1, for example with the first disc. This second rod is adapted to translate along the movement direction coincident with the axis of action K (the axis of the rod coincides with the axis K). The movement of the second rod 134.2 corresponds to the movement of the second fixing assembly 134.1 (and vice versa) and hence of the portion of second membrane 132 in the movement direction, thereby allowing the volume variation of the second portion of storage chamber 130.
[0149] As said, the second elastic contrast device 131 comprises a second elastic contrast body 135 adapted to generate an elastic contrast to the movement of the second rod 134.2, or of the second fixing assembly 134.1, i.e., of the second membrane 132 from the first position to the second position.
[0150] In practice, the second movable element comprises the second membrane 132 which is connected, with seal, to the first chamber part 130 and a slider (the two discs fixed to the second rod) is fixed to the second membrane 132, adapted to interact with the second elastic contrast body 135 to allow movement of part of the membrane in order to vary the volume of the portion of chamber.
[0151] The second elastic contrast body 135, for example a cylindrical helical spring, rests with one end thereof against the bottom 133.1 of the second dome 133, which forms an abutment stop for the spring 135, and the opposite end is in contact with a abutment on the second disc of the second fixing assembly 134.1.
[0152] A sleeve 133.2, which is surrounded by the spring 135, develops from the bottom 133.1 of the second dome 133.
[0153] A guide system 144 along the axis K is associated with the first and with the second movable element 124, 134. For example, this guide system comprises a duct 145 coaxial to K, produced in the second rod 134.2 and open toward the first rod, with the first rod 124.2 which slides, at least for part of its travel, within the duct 145. A bushing 146 is slidingly coupled at one end with the outer surface of the second rod 134.2, and at the opposite end, with the outer surface of the first rod 124,2, so as to form a guide element when the two portions of chamber are at the maximum expansion, as shown in FIG. 7.
[0154] It is understood that, in other examples, the guide system could be made with the first and the second rod housed externally to the portions of chamber, for example within the respective domes 123,133, and guided within the sleeves 123.2, 133.2.
[0155] It is understood that in other embodiments, the guide system might not be present, with the discs that move as a result of the shape of the membranes 22, 122.
[0156] The single chamber A formed by the first and by the second portion of chamber 120, 130, has at least one passage 127 for entry and / or exit of the liquid into / from the chamber. Preferably, said passage 127 is provided on the side of the casing 140, for example at the height of the plane W.
[0157] This passage 127 is operatively connected, through a respective duct 147, with the compartment of the pump 109, in which the liquid is substantially at the same pressure as the outlet pressure 103, i.e., the delivery pressure of the pump.
[0158] Also in this example, just as in the example of the other FIGS. 2-5, the portions of storage chamber present in the tank 10 can be considered substantially the same, or all have the same (minimum and maximum) volume; therefore, what makes the expansion of the portions of chamber 120, 130 differ is the different stiffness value of the elastic contrast bodies 125, 135.
[0159] It is understood that in other embodiments, the stiffness of the two springs can be the same and the expansion of the two portions of chamber, i.e., the volume variation therein, can be the same.
[0160] For one module, for a given pressure value in the portions of storage chambers 120, 130, a first volume variation of the first portion of storage chamber 20 is associated with the first elastic contrast device and a second volume variation of the second portion of storage chamber is associated with the second elastic contrast device, which differs from the first variation (the first elastic contrast device and the second elastic contrast device are configured to allow different storage volumes for the two portions of storage chambers). In general, with several modules, it is preferable that for a given pressure value of the liquid, the elastic contrast devices are configured to allow different storage volumes in all the portions of storage chambers.
[0161] In substance, the liquid in the single storage chamber A, formed by the portions of chamber 120 and 130, expands or contracts the volume of the chamber A acting in a different way on the two membranes 122, 123, as a function of the stiffness of the elastic contrast element associated with the respective membrane. If a dividing partition were to be placed along W to divide the chamber A physically into two sub-chambers (corresponding in practice to the portions of chamber 120, 130) each with its own entry / exit (for example each with half of the passage 127), this would give a solution equivalent to the one described in example 1 of the present description (naturally with a different arrangement of the elastic contrast elements, or the springs), or, from a practical viewpoint, it would correspond to the case of two tanks as described in EP4015826 arranged opposite each other and with axis of action of the elastic contrast elements coaxial to each other.
[0162] Both for this example and for the previous example, distribution of the spaces around a central axis of two storage chambers allows a such tank to be used within submersible pumps, in which the size of the casing of the pump has a mainly axial dimension.
[0163] For example, FIG. 9 shows a diagram of submersible pump, wherein an impeller assembly 1005, a motor 1008, and a tank according to the invention are arranged along the main axis within an outer casing 1001 with prevalent axial development. In FIG. 9 the tank is that of the first example (i.e., relating to FIGS. 2-5, but also the tank of the second example, or a tank according to the invention with yet a further different embodiment from the one described above in detail, can equally be used. In practice, in this application, the tank is arranged within the casing and not on its outer edge, as in the examples described previously, with particularly limited overall dimensions.
[0164] It is understood that the description illustrated merely represents possible non-limiting embodiments of the invention, which can vary in forms and arrangements without departing from the concept on which the invention is based. Any reference numbers in the appended claims are provided purely to facilitate reading of the claims in the light of the description above and of the accompanying drawings and do not in any way limit the scope of protection.
Claims
1-28. (canceled)29. A water storage tank, comprising at least one first and at least one second portion of storage chamber adapted to contain storage water and wherein the water contained in said portions of storage chamber has the same pressure and defining respective elastically variable storage volumes and wherein a first elastic contrast device to the expansion of the respective storage volume is associated with said first portion of storage chamber, and a second elastic contrast device to the expansion of the respective storage volume is associated with said second storage chamber, whereby an increase in the pressure of the water in the tank corresponds to an expansion of the storage volumes overcoming the contrast of the respective elastic contrast devices, while a decrease in the pressure of the water in the tank corresponds to a contraction of said storage volume, and wherein each said elastic contrast device has a main direction of contrast to the expansion, wherein said two elastic contrast devices are arranged opposite each other, so that the respective main directions of contrast to the expansion have opposite directions, wherein each said elastic contrast device comprises:a movable element adapted to move, at least in part, from a first position corresponding to a minimum volume that can be occupied by the water in the chamber, to a second position corresponding to a maximum volume that can be occupied by the water in the chamber; andan elastic contrast body adapted to generate an elastic contrast to the movement of the movable element from the first position to the second position.
30. The tank according to claim 29, wherein the main directions of contrast to the expansion of said opposed elastic contrast devices substantially coincide in a single axis of action, with opposite directions.
31. The tank according to claim 29, wherein said elastic contrast body is arranged externally to said portion of storage chamber, between said movable element and an abutment stop, and is configured to compress in the direction from said movable element to said abutment stop.
32. The tank according to claim 29, wherein at least one said movable element is integral with, or forms, a wall portion of one said portion of storage chamber, and the movement of at least part of said movable element allows expansion of the volume of the portion of storage chamber.
33. The tank according to claim 29, wherein each portion of storage chamber has a first part of chamber portion with a fixed volume and a second part of chamber portion with a variable volume defined by the movement of the movable element of the respective elastic contrast device.
34. The tank according to claim 33, wherein said movable element comprises a membrane connected, with seal, to said first chamber part.
35. The tank according to claim 33, wherein a slider is fixed to said membrane, adapted to interact with said elastic contrast body to allow movement of part of the membrane in order to vary the volume of the chamber.
36. The tank according to claim 29, wherein, for a given pressure value in said portions of storage chambers, said at least one first elastic contrast device being associated with a first volume variation of at least one respective first portion of storage chamber, and said at least one second elastic contrast device being associated with a second volume variation of said at least one respective second portion of storage chamber, and wherein said first and second volume variations are different from each other, or said at least one first elastic contrast device and said at least one second elastic contrast device are configured to allow different expansion volumes for said at least one first and at least one second portion of storage chamber, said elastic contrast devices being configured to allow different expansion volumes in all the portions of storage chambers.
37. The tank according to claim 29, wherein at least two of said elastic contrast devices comprise a different elastic stiffness to each other.
38. The tank according to claim 29, wherein said portions of storage chambers all have the same minimum volume and maximum volume that can be occupied by the water.
39. The tank according to claim 29, wherein said at least two portions of storage chambers have a first part of chamber portion with a fixed volume and a second part of chamber portion with a variable volume defined by the movement of said movable element, wherein the fixed volume of said first part of chamber portion is the same for at least two said portions of storage chambers, and wherein said at least two portions of storage chambers are associated with elastic contrast bodies with different stiffnesses which allow different expansions of said portions of chambers, whereby, with the same pressure of the water in the at least two said portions of storage chambers, said portions of chambers have different volumes.
40. The tank according to claim 29, wherein said first and second portion of storage chamber form a single storage chamber.
41. The tank according to claim 40, wherein said single storage chamber comprises a central casing wherein at least part of said first and second portion of single chamber are defined, and on two open opposite sides of said casing and closed by two opposite domes facing each other with their concave parts, within which respective elastic contrast bodies are housed.
42. The tank according to claim 41, wherein the edges of said membranes are fixed, with seal, on the open end edge of the domes.
43. The tank according to claim 29, comprising at least one first storage chamber formed by said at least one first portion of storage chamber and at least one second storage chamber formed by said at least one second portion of storage chamber.
44. The tank according to claim 43, wherein the first contrast device associated with the first storage chamber is arranged at least partly within the second contrast device associated with the second storage chamber.
45. The tank according to claim wherein the elastic contrast body of the first elastic contrast device associated with the first storage chamber is mainly arranged within the space occupied by the elastic contrast body of the second elastic contrast device associated with the second storage chamber.
46. The tank according to claim 44, wherein the movable element of the first elastic contrast device is adapted to slide within an axial channel defined within the movable element of the second elastic contrast device, or vice versa the movable element of the second elastic contrast device is adapted to slide within an axial channel defined within the movable element of the first elastic contrast device.
47. The tank according to claim 29, comprising an outer casing defining a central housing and wherein respective closing lids are fixed to two opposite ends of said housing, whereby said first and said second storage chamber are defined at said closed ends, and wherein said first and second elastic contrast devices are arranged in said central housing, adapted to act in contrast according to an opposite direction.
48. The tank according to claim 47, wherein for each said chamber the respective lid defines part of said first chamber part and at least one passage is defined on said lid for entry and / or exit of the storage water and wherein the passages of said first and second chambers are at the same pressure.
49. The tank according to claim 47, comprising a modular structure, provided with at least one module, wherein each module comprises one said central housing with two said storage chambers at the opposite ends, and wherein, in the case of at least two modules, the housings of said modules have respective central axes which are parallel and are placed side by side.
50. The tank according to claim 29, wherein, for a given pressure value in said storage chambers, said at least one first elastic contrast device being associated with a first volume variation of at least one respective first storage chamber, and said at least one second elastic contrast device being associated with a second volume variation of said at least one respective second storage chamber, and wherein said first and second volume variations are different from each other, or said at least one first elastic contrast device and said at least one second elastic contrast device are configured to allow different expansion volumes for said at least one first and at least one second storage chamber, said elastic contrast devices being configured to allow different expansion volumes in all the storage chambers.
51. The tank according to claim 29, wherein at least two of said elastic contrast devices comprise a different elastic stiffness to each other.
52. The tank according to claim 29, wherein said portions of storage chambers or complete storage chambers all have the same minimum volume and maximum volume that can be occupied by the water.
53. The tank according to claim 29, wherein said at least two storage chambers have a first chamber part with a fixed volume and a second chamber part with a variable volume defined by the movement of said movable element, wherein the fixed volume of said first chamber part is the same for at least two said storage chambers, and wherein said at least two storage chambers are associated with elastic contrast bodies with different stiffnesses which allow different expansions of said chambers, whereby, with the same pressure of the water in the at least two said storage chambers, said chambers have different volumes.
54. A hydraulic pump comprising a path for the water from at least one suction inlet of the water in the pump to a delivery outlet of the water from the pump and, along said path, downstream of said inlet, a pressure section configured to increase the pressure of the water, downstream of said pressure section, a storage tank for pressurized the storage tank comprising at least one first and at least one second portion of storage chamber adapted to contain storage water and wherein the water contained in said portions of storage chamber has the same pressure and defining respective elastically variable storage volumes and wherein a first elastic contrast device to the expansion of the respective storage volume is associated with said first portion of storage chamber, and a second elastic contrast device to the expansion of the respective storage volume is associated with said second storage chamber, whereby an increase in the pressure of the water in the tank corresponds to an expansion of the storage volumes overcoming the contrast of the respective elastic contrast devices, while a decrease in the pressure of the water in the tank corresponds to a contraction of said storage volume, and wherein each said elastic contrast device has a main direction of contrast to the expansion, wherein said two elastic contrast devices are arranged opposite each other, so that the respective main directions of contrast to the expansion have opposite directions, wherein each said elastic contrast device comprising a movable element adapted to move, at least in part, from a first position corresponding to a minimum volume that can be occupied by the water in the chamber, to a second position corresponding to a maximum volume that can be occupied by the water in the chamber; and an elastic contrast body adapted to generate an elastic contrast to the movement of the movable element from the first position to the second position, wherein said at least one first and at least one second portion of water storage chamber are all placed at the same water delivery pressure.
55. A hydraulic pump according to claim 54, further comprising an outer casing within which said path for the water is defined, there being provided in said casinga bay for containing at least one impeller of the pump,a compartment for the water at the delivery pressure of the pump, said compartment being configured on one side of said bay, so as to develop approximately following the development of the axis of rotation of said at least one impeller,and wherein said portions of storage chamber of the tank are in direct communication with said compartment.
56. A hydraulic pump according to claim 54, wherein said pump is an submersible pump with axial development and at least one tank is arranged within the casing of the pump, with the axis of action of the elastic contrast devices that develops parallel to the axis of axial development of the submersible pump.
57. A hydraulic pump according to claim 54, comprising an electronic control device, to which an electric drive motor of the pressure member of the pressure section of the pump is operatively connected, and a pressure switch, adapted to gauge the pressure in the area between the delivery section and the delivery outlet of the water, whereby said electric motor is adapted to operate said pressure member upon reaching a first pressure value measured by said pressure gauge, and is adapted to interrupt the operation of said pressure member upon reaching a second pressure value measured by said pressure gauge, greater than said first value.