Technical field of the Invention

The present invention relates generally to an application for handling liquid, more precisely a pump station especially suitable for wastewater. According to a first aspect, the present invention relates to a pump station comprising a tank with a base and a circumferential 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

Known pump stations generally comprise a tank, also called a sump, and at least one pump arranged in said tank. The pump is of a submersible type, i.e. arranged to be submersed 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 generally is 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 must 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 is

connected correctly to each other, before the installation is completed and the pump is tested.

The pumped waste water, i.e. treated by 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

transport 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 works. If the allowed rest volume 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 to enter the pump without

disturbances 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

aforementioned 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. In theory the rest volume will be zero.

It is another object of the present invention to provide a pump station, where the pump, the control unit and the outlet tube 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 .

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 same comprises at least one insert arranged in said tank and arranged axially displaceable in said tank between the lower rest position and a floating position in the 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.

According to a second aspect of the present invention, there is provided an insert, which is characterized in that the same is arranged to be a axially displaceable in a tank of the pump station between a lower rest position and a floating position in the 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.

Thus, the present invention is based on the insight that by placing the pump in a floating insert that follows the level of the liquid in the tank of the pump station, a robust construction that can be tested in advance and without need for complex/expensive extra equipment for installation/ submerging the pump in the pump station at the same time as the rest volume in the tank can be minimized, is obtained.

In a preferred embodiment of the present invention, the insert comprises a control unit arranged in the container and operatively connected to said pump. This means that a

certified electrician is not needed 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, the shell of said container comprises a bottom and a wall axially extending from said bottom, wherein the through-hole of the shell is arranged in the bottom of the shell. Thereby a region around the inlet of the pump is achieved, that with margin is free from obstacles when the insert is floating in the tank.

In yet another preferred embodiment, the inlet of the pump comprises an inlet pipe that protrudes relative the bottom of the shell, wherein the inlet tube preferably is arranged to engage the base of the tank when the insert is in the lower resting position. This means that the rest volume in the tank is more or less equal to zero, and this is due to the pump that continuous to pump in practice until air is sucked into the inlet pipe, and this occurs after the liquid level of the tank is below the mouth of the inlet pipe. Preferably, the pump station has an inlet that opens into the base of the tank, to prevent incoming liquid to enter the insert from above.

It is preferred that the pump station comprises guiding means arranged between the wall of the tank and the shell of the container, in order to prevent a jamming drawer effect between the insert and the tank.

Further advantages with 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 accompanying drawings, in which:

Fig. 1 is a schematic cut open cross sectional side view of an inventive pump station comprising an inventive insert,

Fig. 2 is a schematic cut open side view of the insert

floating in the tank,

Fig. 3 is a schematic cut open side view of the insert in a resting position,

Fig. 4 is a schematic perspective view from above of the

insert,

Fig. 5 is a schematic perspective view from below of the

insert,

Fig. 6 is a magnified schematic cut-open side view of a part of the insert according to a first embodiment,

Fig. 7 is a magnified schematic cut-open side view of a part of the insert according to a second embodiment, and Fig. 8 is a schematic cut-open side view of an alternative embodiment of the tank and the insert.

Detailed description of preferred embodiments of the inven ^¬ tion

Initially, reference is made to figure 1, which

schematically shows a pump station, generally designated 1, especially suitable for waste water, as well as the

parts/details of the pump station.

The pump station 1 comprises a tank, generally designated 2, and a removable cover 3 that belongs to the tank 2. The purpose of the cover 3 is to prevent living creatures from falling into the tank 2 and hurt themselves, and to prevent stinking gases from spreading. The cover 3 is preferably shaped as a plug being insertable into the tank 2, whereon a radially extending flange 4 of the cover 3 rests against an upper edge 5 of the tank 2 of the pump station 1. It shall be mentioned that the cover 3 in an alternative embodiment, not shown, may comprise a foldable cover allowing access to the inner of the pump station 1, with the advantage that it is not necessary to remove the whole cover 3 in order to allow access to the inside of the pump station.

The tank 2 comprises a base, generally designated 6, and a circumferential wall 7 axially extending from said base 6. In a typical installation, the tank 2 is buried in the ground, wherein only the cover 3, and eventually an upper end of the tank 2 is visible, whereon the base 6 rests against a ground and carries the pump station 1. Preferably, the base 6 has a bottom surface 8 and a surface 9 inclined towards the bottom surface 8. The angle a between the inclined surface 9 and a horizontal plane is preferably larger than 45° and less than 70°. Preferably the base 6 is funnel shaped, or with other words exhibits the shape of an upside-down truncated cone, i.e. the bottom surface 8 is surrounded by the inclined surface 9 on all sides, where the bottom surface 8 is

planar/horizontal. Preferably, the tank has a circular cross- section, seen in a radial plane, the cross section of the tank 2 may exhibit other shapes, for example the shape of a polygon such as a quadrangle or a hexagonal. The wall 7 of the tank 2 is vertical and exhibits an equal cross-section in each radial plane along the axial extension of the wall 7.

The base 6 of the tank 2 may be prefabricated as a single unit whereon one or several standard tubes, manufactured by concrete or plastic, or the like is placed on the base 6 and forms the wall 7 of the tank 2, alternatively the whole tank 2 may be prefabricated in one piece. In yet another

embodiment may the base 6 of the tank 2 be casted directly on the installation site.

The wall 7 comprises, preferably in the region of the upper end of the wall 7, an outlet 10 from the pump station

1. The outlet 10 extends in a radial direction from the wall 7 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. The pump station 1 also comprises in the region of the upper end of the wall 7 a spillway overflow to prevent overflow of the pump station 1. The spillway overflow 11 extends in a radial direction from the wall 7 of the tank

2. The spillway overflow 11 is arranged at a level below the outlet 10 of the pump station 1.

Furthermore, the pump station 1 has an inlet 12 that preferably opens into the base 6 of the tank 2, most

preferably in the inclined surface 9 of the base 6. It is also possible that the inlet 12 of the pump station 1 opens into the region of the lower end of the wall 7 of the tank 2. The inlet 12 protrudes in a radial direction from the tank 2.

It is essential for the present invention that the pump station 1 comprises at least one insert, generally designated 13, which is arranged in the tank 2 of the pump station 1. The insert 13 is arranged to be axially displaceable in said tank 2 between a lower resting position and a floating position in the tank 2. The insert 13 is arranged to be lifted out of the tank 2 and lowered into the tank 2 as a single unit. During operation, the insert 13 is arranged in the tank 2 and is axially displaceable by floating on the liquid in the tank 2, and when the liquid level in the tank 2 is changed the insert 13 is displaced jointly. The inlet of the pump station 1 shall open at a level below the upper edge of the insert 13 when the insert is in the resting position.

Reference is now also made to figure 2-5, which discloses the insert 13 according to a preferred embodiment, where figure 2 disclose the insert 13 positioned in the floating position and figure 3 disclose the insert 13 in the resting position .

The insert 13 comprises a container with a liquid tight shell, generally designated 14, and at least one pump 15 installed in said container. The pump 15 comprises an inlet 16 in fluid tight connection with a through hole 17 in the shell 14. Accordingly, the pump 15 is arranged on one side of the shell 14 and sucks liquid into the pump 15 from the opposite side of the shell via the inlet 16. During operation of the pump 15 the insert 13 sinks in the tank 2, and when the pump 15 is inactive the insert 13 rises in the tank 2. According to an alternative embodiment, the inlet 16 of the pump 15 is in fluid tight connection to two or more through- holes in the shell 14. In the shown embodiments, the pump is arranged in a standing position, other positions are

possible, such as lying down or inclined.

The pump station 1 may comprise one or more inserts 13, each comprising one or more pumps 15. According to the most preferred embodiment the pump station 1 comprises an insert 13 with one or two pumps 15. According to the embodiment shown in the enclosed drawings the pump station 1 comprises one insert 13 having one pump 15. In the situation where the pump station 1 comprises several inserts 13 these are arranged beside each other, and in the situation where an insert 13 comprises several pumps 15, each pump has an inlet in fluid tight connection with a respective through hole in the shell. It shall be pointed out that the alternation between which of the inserts 13 and/or pumps 15 that is operative is performed in a conventional manner. According to an alternative embodiment, where the insert 13 comprises several pumps 15, the inlets of two or more pumps 15 are in fluid tight connection with a common through hole in the shell 14. The insert 13 and the tank 2 are in the shown embodiment arranged concentric. Preferably, the insert 13 is rotatable in relation to the tank 2 around an axially

extending geometric axis.

Preferably, the pump 15 is dry installed in said

container, i.e. the pump 15 is surrounded by air/gas and comprises an internal cooling system, and is cooled during operation by means of the pumped liquid passing through the pump 15. According to an alternative embodiment, the insert 13 may in the lower part of the liquid tight shell 14 comprise an automatic one-way valve that drains the container from any liquid collected in the container, when the insert 13 is in the resting position. As an alternative to a dry installed pump the container may comprise a cooling liquid that surrounds the pump 15, the cooling liquid is separated from the pumped liquid. The cooling liquid is in its turn cooled via the shell 14 of the insert 13 by the pumped liquid in the tank 2.

Preferably, the insert 13 comprises a control unit 18 (see figure 2) arranged in the container and operatively connected to the pump 15. The control unit 18 may be arranged on the inside of the shell 14 of the container, and thereby achieve in-direct cooling from the liquid in the tank 2. The insert 13 also comprises in the shown embodiment an outlet pipe 19 connected to the pump 15 and releasable connected to the outlet 10 of the pump station 1. The free end of the outlet pipe 19 preferably comprises a check valve 20 (see figure 1) connected to the outlet 10 of the pump station 1. When the pump station 1 is operable the outlet pipe 19 is connected to the outlet 10 of the pump station 1. The outlet pipe 19 is flexible along the whole length or a part of its length, whereon the inlet pipe 19 may be packed/wired into the insert 13 when the insert 13 is displaced upward. During installation the insert 13 is lowered into the tank 2 and thereafter the outlet pipe 19 is connected, more precisely the check valve 20, to the outlet 10 of the pump station 1 and a power cable 21 of the insert 13 is connected to the power grid. It shall be pointed out that in the shown

embodiment the control unit 18 arranged on the outlet pipe 19 and thereby obtains cooling by means of the pumped liquid that flows through the outlet pipe 19 during operation of the pump 15.

The shell 14 of the container comprises a bottom 22 and a wall 23 axially extending from said bottom 22. The inlet 16 of the pump 15, more precisely the through-hole 17 of the shell 14, is preferably arranged in the bottom 22 of the shell 14.

In the shown embodiment the bottom 22 of the shell 14 has a bottom surface 24 and a surface 25 inclined towards the bottom surface 24, wherein the through hole 17 of the shell 14 is preferably arranged in the bottom surface 24 of the shell 14. The angle β between the inclined surface 25 and a horizontal plane is less than the above-mentioned angle a, and preferably more than 30° and less than 40°.

According to the shown embodiment the bottom 22 of the shell 14 is funnel shaped, i.e. exhibits the shape of an upside-down truncated cone, i.e. the bottom surface 24 is surrounded by the inclined surface 25 on all sides, where the bottom surface 24 is planar/horizontal. Preferably, the shell 14 of the insert 13 has a circular cross-section, seen in a radial plane, the cross section of the shell 14 may exhibit other shapes, such as for example the shape of a polygon such as a quadrangle or hexagonal.

Preferably, the insert 13 and the tank 2 exhibits

corresponding/equal cross-sections, seen in a radial plane, among other things to reduce the cross-sectional area of the radial gap found between the wall 7 of the tank 2 and the wall 23 of the insert 13.

Reference is now also made to figures 6 and 7. The inlet 16 of the pump 15 comprises an inlet pipe 26, that in the shown embodiment is constituted by a single part connected to the pump house of the pump 15, but may alternatively be a part of the pump house of the pump 15. The inlet pipe 26 is arranged to protrude through the through-hole 17 of the shell 14, when the pump 15 is mounted in the container. In the embodiment shown in figure 6, the inlet pipe 26 protrudes from the bottom 22 of the shell 14, when the pump 15 is mounted in the container, and according to the embodiments in figure 7 the bottom 22 of the shell 14 comprises a protruding collar 27 whereon the inlet pipe 26 is inserted into the collar 27. A seal 28 is arranged between the bottom 22 of the shell 14 and the inlet pipe 26 in order to achieve a fluid tight connection between the inlet 16 of the pump 15 and the through-hole 17 of the shell 14.

The inlet tube 26 may be connected to the shell 14 by means of screws, or similar attaching elements, alternatively the pump 15 and the inlet pipe 26 may rest against the inside of the shell 14 and be held in place by means of its own weight .

The lower edge 29 of the inlet pipe 26, and/or the lower edge 30 of the collar 27, is arranged to engage the base 6 of the tank 2 when the insert 13 is in the lower resting

position. More precisely, the insert 13 shall rest against the bottom surface 8 of the tank 2 (stand) when the liquid level in the tank 2 is not sufficiently high to keep the insert 13 floating. In an alternative (not shown) embodiment, the inlet pipe 26 is arranged to be positioned in an axial recess/groove in the bottom surface 8 of the tank 2. Thus, when the insert 13 is in the lower resting position, the insert pipe 26 is at a distance from the bottom of the axial recess/groove, and instead the shell 14 of the insert 13 lies in an axial direction against the base 6 of the tank 2, either against the bottom surface 8 of the base 6 or against the inclined surface 9 of the base 6. An imaginary diameter in a radial plane of the recess/groove is preferably less than 1,5 times a corresponding diameter of the inlet pipe 26.

The lower edge 29 of the inlet pipe 26 may comprise recesses 31, and the lower edge 30 of the collar 27 may comprise corresponding recesses 32, for preventing the pump 15 to suck against the bottom surface 8 of the tank 2. The axial height of the recesses 31 determines the remaining liquid level (and thereby the rest volume) when the pump 15 no longer is able to pump liquid out from the pump station 1. A suitable axial height of the recesses 31 are up to 2 cm, even if larger heights are possible depending on the specific installation .

Preferably, the pump station 1 comprises means arranged to determine the position in axial direction of the insert 13 in relation to the tank 2, with the purpose of knowing how much liquid that remains in the tank 2 and when the pump 15 shall be activated for pumping out liquid from the pump station 1.

In the shown embodiment (see figure 1) the positioning means, or the level apparatus, is a so-called contact free positioning means. The positioning means comprises a light radar unit 33 (for example IR) being arranged in the insert 13 and cooperates with a reflector 34, arranged fixed in the pump station 1 for example radially extending from the inside of the wall 7 of the tank 2 or on the inside of the cover 3. The reflector 34 is arranged on a fixed height in the pump station 1, whereon the liquid level in the tank 2 can be derived from the position of the light radar unit 33 relative the reflector 34. This positioning means is synchronized by means of placing the insert 13 in the resting position, mounting the reflector 34 and thereafter measure the distance there between. The pumped liquid is not in contact with the positioning means and a result of that is that the pumped liquid and the solid matter therein, do not risk affecting the same negatively. According to an alternative embodiment, several level sensor organs (not shown) are arranged in the wall 7 of the tank 2 and when the upper edge of the insert 13 is in level with a respective level sensor organ the position in axial direction of the insert 13 may be determined in relation to the tank 2.

Preferably, the pump station 1 comprises guiding means (not shown) arranged between the inside of the wall 7 of the tank 2 and the outside of the shell 14 of the insert 13, to prevent the insert 13 from being jammed in the tank 2 above the liquid level or below the liquid level.

Preferably, the insert 13 comprises a flexible flange 35 radially extending and arranged to abut the inside of the wall 7 of the tank 2, in order to center the insert 13 in the tank 2 and scrape possible remaining fat from the inside of the wall 7 of the tank 2 when the insert 13 is displaced downwardly in connection with pumping out liquid from the pump station 1.

Reference is now made to figure 8 that disclose an alternative embodiment of the insert 13 and the tank 2. In the shown embodiment the bottom 22 of the insert 13 consists entirely of the bottom surface 24, and the base 6 of the tank 2 consists entirely of the bottom surface 8. It shall be realized that the base 6 of the tank 2 may exhibit the shape according to figure 8 simultaneously as the bottom 22 of the insert 13 exhibits the shape according to figure 3.

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.