Technical field of the Invention

The present invention relates generally to an application for handling liquid, more specifically to a pump station especially suitable for wastewater. In particular the present invention according to a first aspect relates to a pump station comprising a tank with a base and an enclosing wall extending axially from said base. According to a second aspect, the present invention relates to an insert for such a pump station.

Background of the Invention

Pump stations according to prior art generally comprises a tank, also called a sump, and at least one pump arranged in said tank. The pump is of submersible type, i.e. arranged to be submerged into the liquid that flows into the tank and later being pumped away from the tank by means of the pump. In order to lower the pump into, and hoist the pump up from, the tank the pump is in general guided by means of a guiding element, wherein automatic connection of the pump with an outlet pipe via an outlet connection, and disconnection of the pump from the outlet connection, respectively, is

performed. This requires complicated and expensive extra equipment, in addition to the pump and the outlet pipe.

Moreover, it shall be pointed out that the pump is

transported to the pump station as a separate unit and must be connected to a control unit/power box by a certified electrician on site. Thus, it is not known if the system/pump station functions properly, i.e. the pump and the control unit communicates, and if the pump and the outlet pipe are correctly connected to each other, before the installation is accomplished and the pump is tested.

The pumped waste water, i.e. treated in the pump station, is generally disgusting and can furthermore be unhealthy for humans, the above disclosed arrangement entail that it is unnecessary for service personal to be in the tank during connection, and disconnection/connection of the pump from/to the outlet pipe, respectively. However, the problem that the submersible pump is still covered by the content of the waste water when the submersible pump is hoisted up for service remains .

A well-known problem, or whish, within the field of waste water treatment is to minimize the rest volume of waste water that remains in the tank when the pump is not able to tran ^¬ sport more liquid from the pump station. By minimizing the rest volume, as much as possible of the liquid and the solid matter that can be found in the waste water is transported from the pump station to the sewage treatment plant. If the rest volume allowed in the tank is too large, a large amount of solid matter is accumulated in the pump station, which over time might disturb or prevent the pump station from correct operation. A limitation of the installations of today is that the inlet of the pump must be at a minimum distance from the bottom of the tank in order for liquid and solid matter without disturbances to enter the pump for further transportation during normal operation, this causes a

considerable rest volume in the tank for installations of today and has not been minimized to the desired extent.

Object of the Invention

The present invention aims at obviating the aforementio ^¬ ned disadvantages and failings of previously known pump stations, and at providing an improved pump station. A primary object of the present invention is to provide an improved pump station of the initially defined type, which causes the rest volume of the pump station to be considerable smaller compared to previously known pump stations. It is another object of the present invention to provide a pump station, where the pump, the control unit and the outlet pipe are connected and tested before they are delivered to the site for installation/operation of the pump station. On site, the insert is lowered into the tank of the pump station, the power cable is connected to the power grid and the pump station is ready for use. It is another object of the present invention to provide a pump station, in which the outside of the pump is clean even if the pump is submerged in the tank of the pump station. It is yet another object of the present invention to provide a pump station of a modular construction and wherein the number of pumps can be easily varied.

Summary of the Invention

According to the invention at least the primary object is attained by means of the initially defined pump station and insert, having the features defined in the independent claims. Preferred embodiments of the present invention are further defined in the dependent claims.

According to a first aspect of the present invention, there is provided a pump station of the initially defined type, which is characterized in that the pump station

comprises an insert arrangement with at least one insert being releasable anchored in said tank, wherein said at least one insert comprises a container with a liquid tight shell and at least one pump installed in said container, wherein an inlet of said at least one pump is in fluid tight connection with a through hole in the shell of the container.

According to a second aspect of the present invention, there is provided an insert, which is characterized in that the insert is arranged to be releasable anchored to a tank of the pump station, wherein said insert comprises a container with a liquid tight shell and at least one installed pump in said container, wherein an inlet of said at least one pump is in fluid tight connection with a through hole in the shell of the container.

Thus, the present invention is based on the insight that by placing the pump in an insert that is lowerable into the tank of the pump station, a robust design that can be tested in advance and without complex/expensive extra equipment for installation/submersing the pump in the pump station is obtained, at the same time as the rest volume of the tank can be minimized and the number of pumps in the pump station can be easily varied.

In a preferred embodiment of the present invention, the shell of the container comprises a bottom and a wall axially extending from said bottom, wherein the inlet of said at least one pump is in fluid tight connection with a through hole in the wall of the shell. In this way, the inlet of the pump is not risked to be blocked when the bottom of the insert is standing on the base of the tank.

According to a preferred embodiment of the present invention, the insert comprises a control unit arranged in the container and operatively connected to said pump. This entail that a certified electricity technician is not

required for connecting the pump to the control unit, instead the power cable of the control unit is connected to a mains connection and the pump station is ready for use.

According to a preferred embodiment of the present invention, the bottom of the insert comprises at least one recess. This prevents solid material that might be in the tank during lowering of the insert from preventing correct installation of the insert in the tank.

According to a preferred embodiment of the present invention, the base of the tank comprises a funnel and a seat, wherein the funnel in an upper end is connected to the wall of the tank and in the lower end is connected to said seat, and wherein said at least one insert is connected to said seat, and wherein the lower end of the funnel of the base is placed in flush with a lower edge of the through-hole in the wall of the container when the insert is in engagement with said seat. In this way the rest volume of the tank is minimized.

In another preferred embodiment, the inlet of the pump station opens in the funnel of the base. The incoming flow to the pump station contributes to prevent sedimentation of solid matter. Further advantages and features of the invention will be apparent from the other dependent claims as well as from the following detailed description of preferred embodiments.

Brief description of the drawings

A more complete understanding of the abovementioned and other features and advantages of the present invention will be apparent from the following detailed description of preferred embodiments with reference to the appended draw ^¬ ings, wherein:

Fig. 1 is a schematic partially cut-open perspective view from above of a pump station according to the invention,

Fig. 2 is a schematic partially cut-open perspective view

from above of a pump station according to Fig. 1, wherein certain details are removed,

Fig. 3 is a schematic cut-open side view of the tank,

Fig. 4 is a schematic cut-open side view of the tank and two inserts lowered into the tank,

Fig. 5 is a schematic cut-open cross sectional side view of a half pump station according to an alternative embodiment,

Fig. 6 is a schematic perspective view from below of an

insert according to a first embodiment of the invention,

Fig. 7 is a schematic perspective view from above of the

insert according to Fig. 6,

Fig. 8 is a schematic perspective view from below of an

insert according to a second embodiment of the invention,

Fig. 9 is a schematic perspective view from above of the

insert according to Fig. 8,

Figs. lOa-f are schematic plan views from above of the tank and one or more inserts, which disclose alternative compositions of inserts in one and the same pump station . Detailed description of preferred embodiments of the inven ^¬ tion

Initially, reference is made to figures 1 and 2, which schematically disclose a preferred embodiment of a pump station according to the invention, generally designated 1, which is especially suitable for waste water. Such pump stations 1 typically has a diameter approximately in the range of 3-4 meter and a height approximately in the range of 6-8 meter.

The pump station 1 comprises a tank, generally designated 2, which is the border of the pump station 1 toward the surroundings (see also figure 3, which only disclose said tank 2) . The tank 2 comprises a base 3 and a circumferential wall 4 axially extending from said base 3. The pump station 1 further comprises a lid (not shown) being fully or at least partly removable/openable in order to allow access to the inside of the pump station 1. The purpose of the lid is to prevent living creatures from falling into the tank 2 by mistake, and hurt themselves, and to prevent evil smelling gases from spreading from the pump station 1. Preferably, the tank 2 has a circular cross section, seen in a radial plane, but the cross section of the tank 2 may present other forms, for example a polygonal shape such as a tetragonal or a hexagonal shape. The wall 4 of the tank 2 is vertical and preferably exhibits a uniform cross section in each radial plane along the axial extension of the wall 4.

In a typical installation the tank 2 is buried in the ground and only the lid or eventually an upper end of the tank 2 is visible, the base 3 of the tank 2 rests on the ground and carries the rest of the pump station 1.

Preferably, the base comprises a bottom plate 5 which rests on the ground, wherein the contact area, to the ground, of the bottom plate 5 is approximately equal to the maximum radial cross-sectional area of the tank 2.

The base 3 of the tank 2 may be pre-fabricated as a single unit, whereon one or more tubes of standard type, made of for example plastic or the like, is placed on the base 3 and constitutes the wall 4 of the tank 2. Alternatively, the whole tank 2 may be pre-fabricated in one piece. In another embodiment the base 3 of the tank 2, and eventually the wall 4 of the tank 2, may be casted directly on the installation site. In the shown embodiment the base 3 of the tank 2 has an upper rim 6, wherein the wall 4 is telescopically lowerable inside said rim 6 and rests against a step 6' of the rim 6. Preferably, a seal is arranged at the interface between the wall 4 and the base 3 to ensure that no leakage from the pump station occurs.

The pump station 1 comprises an outlet 7, preferably arranged in the region of the upper end of the wall 4. The outlet 7 extends in the radial direction from the wall 4 of the tank 2 and is arranged to be connected to a waste water pipe system (not shown) that extends to a sewage treatment plant. Furthermore, the pump station 1 comprises an inlet 8 that preferably opens into the base 3 of the tank 2. It is also possible that the inlet 8 of the pump station 1 opens into the region of the lower end of the wall 4 of the tank 2. The inlet 8 extends in the radial direction from the tank 2.

Reference is now primary made to figure 3. The base 3 preferably comprises a funnel, generally designated 9, and a seat 10. The upper end of the funnel 9 is connected to the wall 4 of the tank 2 and the lower end of the funnel is connected to said seat 10. In the disclosed embodiment the seat 10 is essentially limited by vertical walls 11 and a planar bottom area 12 of the base 3, wherein the bottom area 12 is adjacent the bottom plate 5 of the base 3. Preferably, the funnel 9 of the base 3, seen in an axial cross-section, has a straight upper part 13 and a curved lower part 14, which are connected to each other. The angle (a) between the upper part 13 of the funnel 9 and a horizontal plane is preferably larger than 45 degrees and less than 70 degrees. The inlet 8 of the pump station 1 preferably opens into the funnel 9 of the base 3, and most preferably in the curved lower part 14. The straight upper part 13 of the funnel 9 of the base 3 is adjacent the wall 4 of the tank 2 and the curved lower part 14 of the funnel 9 of the base 3 is

adjacent the seat 10 of the base 3. The curved lower part 14 of the funnel 9 has an essentially axial tangent in connection to the straight upper part 13 of the funnel 9 and an essentially radial tangent in connection to the seat 10 of the base 3. It shall be pointed out that it is the shape of the inner surface of the funnel 9 that is referred to above, and it shall also be pointed out that the outer surface of the base 3 not necessarily must mirror the inner surface of the base 3 as shown in the figures, but it is preferred if the base 3 for example is made of plastic, glass fibers, or the like.

Reference is now also made to figure 4. It is essential for the present invention that the pump station 1 comprises an insert arrangement with at least one insert, generally designated 15, being releasable anchored/connectable to the tank 2 of the pump station 1. By releasable anchored/connect ^¬ able it is meant that the insert 15 is stationary/immobile in the tank 2 when the pump station 1 is ready for operation, and that the insert 15 thereto can be released and removed from the tank 2 in connection with for example maintenance. Preferably, the insert arrangement of the pump station 1 comprises two or more inserts 15, other compositions of the insert arrangement will be described in more detail below.

The insert 15 comprises a container 16 with a liquid tight shell. Preferably, the shell of the container 16 comprises a bottom 17 and a wall 18 axially extending from said bottom 17.

The insert 15 is arranged to be lifted out and lowered into the tank 2 as a complete unit. The inlet 8 of the pump station 1 shall mouth at a level below the upper edge of the insert 15 to prevent incoming waste water from entering the container 16.

The insert 15 comprises at least one pump 19 installed in said container 16. The pump 19 comprises an inlet 20 being in fluid tight connection with a through hole 21 in the shell of the container 16. Thus, the pump 19 is arranged on one side of the shell of the container 16 and suck liquid into the pump 19 from the opposite side of the shell via the inlet 20 and the through-hole 21 of the shell of the container 16. Preferably, the inlet 20 of the pump 19 is in fluid tight connection with a through-hole 21 in the wall 18 of the container 16, as shown in figure 4. In the shown embodiment the pump 19 is arranged horizontally, other positions are possible, such as standing or inclined. In an alternative embodiment, the inlet 20 of the pump 19 is in fluid tight connection with two or more through holes in the shell of the container 16.

It shall be pointed out that each insert 15 may comprise one or more pumps 19, the insert 15 according to the most preferred embodiment comprises only one pump 19, and in the situation when each insert 15 comprises several pumps 19, each pump has an inlet that is in fluid tight connection with a respective through hole in the shell of the container.

According to an alternative embodiment, the insert 15

comprises several pumps 19, the inlets of two or more pumps 19 are in fluid tight connection with one through hole in the shell of the container. Preferably, the pump 19 is connected to the shell of the container 16, the wall 18 in figure 4, by means of being bolted to the inside of the shell of the container 16, preferably by means of screws from the outside of the container 16.

Furthermore, it is preferred that the pump 19 is dry installed in said container 16, i.e. the pump 19 is

surrounded by air/gas and comprises an internal cooling system, and thereby during operation the pump 19 is cooled by means of the pumped liquid that passes through the pump 19. According to an alternative embodiment, the insert 15 may in the lower end of the shell of the container 16 comprise an automatic check valve that drains the container from possible liquid, collected in the container, when the pump 19 has pumped out liquid and stopped. As an alternative to a dry installed pump the container 16 may comprise a cooling liquid surrounding the pump 19, which cooling liquid is separated from the pumped liquid/waste water. The cooling liquid is cooled by means of the shell of the insert 15 and the pumped liquid within the tank 2. Preferably the insert 15 also comprises a control unit 22 arranged in the container 16 and operatively connected to the pump 19. The control unit 22 may for example be arranged on the inside of the wall 18 of the container 16, and thereby be cooled indirectly by means of the liquid in the tank 2. In an alternative embodiment the pump station 1 comprises a central control unit (not shown) which is operatively connected to all pumps 19 in the pump station 1. In the shown embodiment the insert 15 also comprises an outlet pipe 23 connected to the pump 19 and releasably connected to the outlet 7 of the pump station 1. The free end of the outlet pipe 23 preferably comprises a check valve 24 being connectable to the outlet 7 of the pump station 1. When the pump station 1 is operative the outlet pipe 23 of the insert 15 is thus directly or indirectly connected to the outlet 7 of the pump station 1. The upper end of the outlet pipe 23, for example the check valve 24, is preferably arranged in the region of an open upper end of the container 16 of the insert 15.

During installation (or replacement of the insert) the insert 15 is lowered into the tank 2, whereby the insert 15 is engaging the seat 10 of the base 3. More precisely, the bottom 17 of the insert 15 is placed standing on the bottom surface 12 of the seat 10, and the lower end of the wall 18 of the insert 15 is surrounded by vertical walls 11 of the seat 10. It is preferred when the insert 15 is connected to the tank 2 that the lower end of the funnel 9 of the base 3 is in flush with a lower edge of the through-hole 21 in the wall 18 of the container 16. In this way the curved lower part 14 of the funnel 9 functions as a curved inlet pipe in the axial plane intersecting the inlet 20 of the pump 19. If the curved lower part 14 is arranged too close to the

through-hole 21 in the wall 18 of the container 16 the ability of the pumps to suck liquid and solid matter of the liquid, is limited. The inclination of the upper part 13 and the arcuate shape of the curved lower portion 14 causes solid matter in the waste water to slide down to the circular channel 25 formed by the outside of the wall 18 of the container 16 and the inside of the curved shaped lower portion 14 of the funnel 9. The inlet 20 of the pump 19 may have an angle different from the angle of 90 degrees shown in the figures relative the wall 18 of the container 16, in order to achieve a flow along said channel 25 with the purpose to amplify the transport of solid matter towards the inlet 20 of the pump 19. The inlet 8 of the pump station 1 shall preferably not be in line with the inlet 20 of the insert 15, in order to prevent that a stiff oblong object enters the pump chamber of the pump 19 and blocks the

impeller of the pump 19. When the insert 15 is lowered into the tank 2 the outlet pipe 23 is connected to the outlet 7 of the pump station 1. In the shown embodiment the pump station 1 comprises an outlet manifold, generally designated 26, which is arranged between the outlet pipe 23 of the insert 15 and the outlet 7 of the pump station 1. The outlet manifold 26 is arranged to connect several outlet pipes of several inserts with the outlet 7 of the pump station 1. The outlet manifold 26 according to the shown embodiment also comprises a stop valve 27. The outlet manifold 26 is arranged to be customized for a varying number of inserts 15 in the pump station 1. Thereafter a power cable 28 of the insert is connected to the power mains and the insert 15 is ready for use. It shall be pointed out that in the shown embodiment the control unit 22 is arranged on the outlet pipe 23 and thereby obtains cooling from the pumped liquid flowing through the outlet pipe 23, during operation.

Thereto, the insert 15 is secured to the tank 2 in order to prevent the insert 15 from floating and tilting when wastewater is filled in the tank 2. Preferably, an anchoring element 29 is used, placed between the insert 15 and the tank 2, and the anchoring element in the shown embodiment

surrounds the insert arrangement and rests on protrusions 13 extending in a radial direction from the wall 18 of the insert 15, the anchoring element 29 is connected to the wall 4 of the tank 2 in a suitable manner. Thus, the shown

anchoring element is lowered into the tank 2 after the insert arrangement. In an alternative, not shown, the anchoring element 29 is arranged in the tank 2 before the insert 15 is lowered into the tank 2, whereon the insert 15, when the same is placed on the bottom surface 12 of the seat 10, in a suitable manner is connected to the anchoring element 29. In the shown embodiment the anchoring element 29 carries a walking bridge 31, which is provided for use by a service technician during installation and maintenance. It shall be pointed out that in an alternative embodiment the walking bridge and the anchoring element 29 may be the same unit.

Furthermore, the pump station 1 comprises at least one liquid level sensor (not shown) which is arranged to

determine the liquid level in the tank 2 with the purpose of controlling the activation/deactivation of the pump 19. In the preferred embodiment the insert 15 comprises a pressure sensor (not shown) arranged in connection with the pump chamber of the pump 19. Thus, the pressure sensor measure the liquid pressure in the pump 19 caused by the liquid in the tank 2. When the liquid level in the tank 2 reaches a

predetermined, or in another way determined, position the pump 19 is activated for pumping away the wastewater.

Preferably, the pump 19 stops when the liquid level in the tank 2 is lowered so low that air is sucked into the inlet 20 of the pump 19, i.e. slurps. The remaining rest volume of liquid is in this position minimal and occupies only a part of the circular channel 25. Alternatively, the pump 19 may be stopped when the liquid level is at a predetermined position, or in another way determined position.

Preferably, each insert 14 has its own liquid level sensor. In an alternative embodiment, the insert 15 may comprise one or a plurality of continuous or discrete liquid level sensors arranged on the wall 18 of the container 16. In yet another embodiment, the pump station 1 may comprise one or several continuous or discrete liquid level sensors arranged in the tank 2.

Reference is now made to figure 5, which discloses an alternative embodiment of a pump station 1 (only one half of the pump station is shown) . Same or like elements also shown in figure 4 has the same reference number, and only differences in the embodiment according to figure 5 from the embodiment according to figure 4 will be described.

In this embodiment the inlet 20 of the pump 19 is in fluid tight connection with a through hole 21 in the bottom 17 of the container 16, whereon the base 3 of the tank 2 is

arranged to guide the pumped liquid in the tank 2 under the insert 15, via at least one channel extending to the region of the inlet 20 of the pump 19. In the shown embodiment the seat 10 of the tank 2 consists only of the bottom surface 12. It shall be pointed out that in a not shown alternative to this embodiment of the pump station 1, the arched lower part of the funnel 9 of the base 3 may be dispensed, whereon the straight upper part 13 of the funnel 9 forms the whole funnel

9 and extends between the wall 4 of the tank 2 and the seat

10 of the base 3.

Reference is now primarily made to the figures 6-9.

Figures 6 and 7 disclose an insert 15 according to a semi circle embodiment, and figures 8 and 9 disclose an insert 15 according to a quarter circle embodiment. These inserts 15 are equal in function but different in how much of the insert arrangement they form. As shown in the figures, the bottom 17 of the container 16 comprises at least one recess 32, or a cavity open downwardly. In the shown embodiments the insert 15 comprises a series of parallel recesses 32 which are divided by ridges 33. When the insert 15 is lowered into the tank 2, solid matter may be found in the seat 10, and the purpose of the recess 32 is that the solid material shall be accommodated in the recess 32 and thereby correct engagement between the insert 15 and the seat 10 of the tank 2 is not prevented. In an alternative embodiment the bottom 17 of the container 16 comprises several legs (not shown) which are arranged to be placed on the bottom surface 12 of the seat 10.

In the shown embodiment, the insert 15 comprises a

distance means 34 on the outside of the wall 18 of the container 16 arranged to abut against a corresponding

distance means of the nearby inserts 15 in order to prevent sticking/adhesion of the inserts 15. Reference is now made to figures lOa-f, which discloses different compositions of insert arrangement of the pump station 1, the shown configurations shall not be considered to be an exhaustive list of possible combinations.

Preferably, the insert arrangement has a circular cross- section seen in a radial plane, the cross-sections of insert arrangements may exhibit other shapes, for example a shape of a polygon such as a quadrangle or a hexagonal. It is also preferred that the tank 2 of the pump station 1 and the insert arrangement of the pump station 1 are arranged

concentric. The tank 2 of the pump station 1 and the insert arrangement of the pump station 1 may not necessarily exhibit corresponding cross-sections.

In figures 10a and 10b the pump station 1 comprises a pump 19. In figure 10a the pump station comprises an insert 15 that forms the whole insert arrangement. It shall be pointed out that this insert 15 may comprise one or several pumps 19. In figure 10b the insert arrangement of the pump station 1 comprises an inventive insert 15 having a semicircular shape comprising a pump 19 and a semicircular shaped dummy insert 15' that consists solely of an empty container.

In figure 10c the insert arrangement of the pump station 1 comprises two inventive semicircular inserts 15, each

comprising one pump 19.

In figures lOd and lOe, the pump station 1 comprises three pumps 19. In figure lOd the pump station 1 comprises three inventive quarter-circle shaped inserts 15 and a quarter- circle shaped dummy insert 15' that consists solely of a container. In figure lOe, the insert arrangement of the pump station 1 comprises an inventive semicircular insert 15 and two inventive quarter-circle shaped inserts 15, each

comprising one pump 19.

In figure lOf, the insert arrangement of the pump station 1 comprises four inventive quarter-circle shaped inserts 15, each comprising one pump 19.

It shall be pointed out that the alternation between the inserts 15, i.e. which pump 19 or which pumps 19 that are operable, is performed in a conventional manner. Preferably, an insert 15 may be disconnected from the tank 2 and lifted out, and be replaced without interrupting the operation of the pump station. A great advantage with the invention is that the same pump station 1 may be upgraded to include less/more pumps 19 in the event that the conditions for the inflow of wastewater to the pump station 1 change.

Feasible modifications of the Invention

The invention is not limited only to the embodiments described above and shown in the drawings, which primarily have an illustrative and exemplifying purpose. This patent application is intended to cover all adjustments and variants of the preferred embodiments described herein, thus the present invention is defined by the wording of the appended claims and thus, the equipment may be modified in all kinds of ways within the scope of the appended claims.

It shall also be pointed out that all information about/concerning terms such as above, under, upper, lower, etc., shall be interpreted/read having the equipment oriented according to the figures, having the drawings oriented such that the references can be properly read. Thus, such terms only indicates mutual relations in the shown embodiments, which relations may be changed if the inventive equipment is provided with another structure/design.

It shall also be pointed out that even thus it is not explicitly stated that features from a specific embodiment may be combined with features from another embodiment, the combination shall be considered obvious, if the combination is possible.