Centrifugal pump for conveying a fluid

Abstract

The invention relates to a centrifugal pump (10) for pumping a fluid, comprising a pump housing (16) forming a pump chamber (14), an impeller (17) provided in the pump chamber (14) for pumping the fluid, a suction opening (26) provided in the pump housing (16) for drawing the fluid through the impeller (18) into the pump chamber (14), and a check valve (52) provided in the pump housing (16) behind the impeller (18) with respect to the suction opening (26), which closes when fluid enters the pump chamber and / or when air pressure prevails in the pump chamber (14) and allows air to escape from the pump chamber (14) when open.

Description

Technical area

[0001] The invention relates to a centrifugal pump for conveying a fluid, comprising a pump housing forming a pump chamber, an impeller provided in the pump chamber for conveying the fluid, a suction opening provided in the pump housing for sucking the fluid through the impeller into the pump chamber, and a vent opening provided in the pump housing behind the impeller relative to the suction opening. Background of the invention

[0002] Centrifugal pumps are known from the prior art and are used to pump a fluid by means of the rotating movement of an impeller. The fluid to be pumped enters a pump chamber of the centrifugal pump through a suction opening, is captured by the rotating impeller, and then transported into a pipe section, also known as the discharge pipe.

[0003] Due to their robustness against fluids containing solids, centrifugal pumps are used as wastewater pumps, particularly in wastewater lifting stations, where the wastewater is usually collected in a tank for temporary storage. To ensure that the fluid can flow into the pump chamber after each pumping cycle and the centrifugal pump can pump with high efficiency, the centrifugal pump must be vented. For this purpose, it is common practice to provide vent openings in the pump chamber through which the air can escape. The vent opening is usually located at the highest point of the pump chamber; in vertically mounted centrifugal pumps, it is above the impeller.

[0004] When the centrifugal pump is operating, a fluid leakage occurs through the vent opening due to the pressure difference between the higher pressure inside the pump chamber and the lower pressure on the side of the vent opening facing away from the pump chamber. This leakage is typically diverted away from the pump via a vent line or, in the case of wastewater lifting stations, back into the collection tank. However, this leakage has a negative impact on the pump's performance curve.

[0005] FR 1 101 771 A describes a suction and re-suction device for centrifugal pumps, which essentially consists of a vent taken from the medium-pressure zone of the pump body.

[0006] DE 42 06 907 A1 describes a device for removing air for submersible centrifugal pumps having a cavity which is connected to the interior of the pump housing through an opening and to the exterior of the pump housing through an opening, wherein the cavity contains a movable part which is designed as a membrane fastened to the pump housing and which can be made of a plastic film.

[0007] DE 19 14 798 A1 describes a submersible motor pump with a suction or cooling jacket surrounding the motor arranged below the pump and a spring-loaded check valve arranged in the pressure line of the pump.

[0008] GB 2 138 888 A describes a passage connecting the outlet side of an impeller pump to the valve body 1, which is then connected via the passage to an air extraction device.

[0009] EP 3 839 260 A1 describes a centrifugal pump for conveying a fluid with a pump housing forming a pump chamber, wherein an impeller is provided in the pump chamber, and a suction opening is provided in the pump housing for sucking the fluid into the pump chamber. Description of the invention

[0010] Based on this situation, it is an object of the present invention to improve a centrifugal pump and a lifting system of the type mentioned above in such a way that the centrifugal pump or lifting system has an improved characteristic curve

[0011] The object of the invention is achieved by the features of the independent claims. Advantageous embodiments are specified in the subclaims.

[0012] Accordingly, the task is solved by a centrifugal pump for conveying a fluid with a pump housing forming a pump chamber, an impeller provided in the pump chamber for conveying the fluid, a suction opening provided in the pump housing for sucking the fluid through the impeller into the pump chamber, and a check valve provided in the pump housing behind the impeller in relation to the suction opening, which closes when the fluid enters the pump chamber and / or when an air pressure prevailing in the pump chamber and, when opened, allows air to escape from the pump chamber, wherein the check valve is made of a buoyant material and is fastened to the pump housing at its end facing the impeller.

[0013] A key point of the invention is that the pump chamber can be vented through the check valve, which increases efficiency and improves the pump characteristic. On the other hand, after air in the pump chamber has escaped through the check valve, the pump chamber is closed by the check valve when a fluid flow is generated in the pump chamber due to operation of the impeller and / or air pressure is generated in the pump chamber. The proposed solution prevents fluid leakage through a vent opening closed by the check valve, so that the pump characteristic curve increases while the motor power remains the same. Likewise, the risk of a vent channel adjoining the check valve downstream of the vent opening becoming blocked by solids in the fluid, particularly in wastewater, is reduced to a minimum, since no fluid flows through the vent channel during operation.Finally, an increased noise level known from the state of the art is also reduced by such a loss flow in pumps with a vent opening.

[0014] As a result, the proposed centrifugal pump can be used, for example, as a submersible wastewater pump in shafts, enabling pumping to very low water levels without any loss of head and / or a reduction in the pumping curve. This broadens the application range of the centrifugal pump, as the proposed solution also allows residual volume in shafts, including sedimentation, to be pumped much further and deeper. In other words, the proposed solution consists in equipping an otherwise regularly present venting channel with a check valve. This check valve allows air to be evacuated from the pump chamber to pass through, but closes as soon as the fluid to be pumped reaches the check valve.

[0015] In this respect, compared to pumps without a check valve, the hydraulic efficiency of the proposed centrifugal pump is consistently high, even at low discharge heads and high volume flows of the fluid to be pumped. Furthermore, unwanted noise is avoided, enabling quiet pump operation. The centrifugal pump is preferably used for a building's hydraulic system, for example, in a wastewater lifting station. Accordingly, the fluid may also contain solids, which may include contaminants of any kind, such as dirt, paper, feces, or the like.

[0016] In a centrifugal pump, the fluid is transported by the rotation of the impeller. In this context, it is preferably provided that the impeller is connected to a drive motor via a motor shaft extending in the axial direction. During operation, the fluid flows from outside the pump through the suction opening in the pump housing into the pump chamber where the rotating impeller is located. To transport the fluid, a centrifugal force occurring in the radial direction is used in addition to a tangential acceleration of the fluid, so that centrifugal pumps are also referred to as centrifugal pumps. From the pump chamber, the fluid is preferably transported into a line section, which is also referred to as the pressure pipe. For the purpose of venting the pump chamber, the centrifugal pump has a check valve as a vent opening behind the impeller in relation to the suction opening. The check valve is preferably located at the highest point in the pump chamber.The air escaping through the check valve may contain a fluid component. The check valve is preferably provided in a wall of the pump chamber. The check valve or the vent opening can be connected to the vent channel, which can open outside the pump chamber, the centrifugal pump, and / or into a collecting tank.

[0017] In many cases, the suction opening of the centrifugal pump is located at the lowest point of the pump housing so that the centrifugal pump can pump the fluid as far as possible without leaving large amounts of residual fluid below the suction opening. In such vertically installed centrifugal pumps, the axial direction of the motor shaft corresponds to the vertical direction. In vertically installed centrifugal pumps, the check valve as a vent opening is preferably above the height at which the impeller is attached to the motor shaft. However, other designs and installations of the centrifugal pump are also possible in which the motor shaft extends horizontally. In horizontal installation, the suction opening is usually not located at the lowest point of the pump housing.When installed horizontally, the check valve as a vent opening is preferably located next to the impeller's fastening point on the motor shaft and on the side of the impeller facing away from the suction opening.

[0018] The check valve is preferably designed such that it naturally tends towards an open position, for example, is de-energized in the open position. This means that the check valve preferably opens when the fluid in the pump chamber drops and / or the air pressure in the pump chamber drops, for example, below a threshold value. Likewise, the check valve can close when the air pressure in the pump chamber rises above the threshold value. In this respect, the check valve can be designed as a self-opening check valve. Entry of the fluid into the pump chamber means in particular that the check valve closes when the pump chamber is almost completely, preferably completely, filled with fluid and / or the pump chamber on the side of the impeller facing away from the suction opening is filled with fluid. Likewise, entry of the fluid into the pump chamber can mean that the check valve closes above a certain fill level.The same applies to the air pressure prevailing in the pump chamber, namely that the check valve closes when a predefined air pressure is exceeded. In other words, the fluid in the pump chamber and / or the air pressure in the pump chamber acts on the check valve and causes it to close when a certain fill level and / or such an air pressure is exceeded. The check valve preferably tends toward the open position due to gravity. In other words, the check valve preferably opens due to gravity.

[0019] According to a preferred development, the check valve is designed as a check valve, a flap valve, and / or a ball valve. According to a further preferred embodiment, the check valve is designed to close when the fluid and / or air pressure in the pump chamber increases. Preferably, the check valve closes when the fluid and / or air pressure in the pump chamber has exceeded the threshold value and / or opens when the pressure falls below the threshold value.

[0020] According to another preferred embodiment, the check valve is made of a plastic, an elastomer, a fluorinated elastomer or rubber.

[0021] The check valve preferably undergoes a shape change for closing and opening. For example, an upper part can close off the flow of air through the check valve, while a lower part is attached to the pump housing, and a middle part connecting the upper and lower parts is flexibly designed to pivot the upper part relative to the lower part. To support the pivoting, a diameter or material thickness of the middle part can be smaller than that of the upper and / or lower parts. Further preferably, the check valve is designed like a tab or lip and is particularly preferably attached to the pump housing at its lower end.

[0022] In this respect, it has proven advantageous if the check valve is made of an elastomer. In particular, rubber, particularly preferably fluororubber (FKM), has proven to be suitable. Alternatively, it is also possible to use other fluorinated elastomers, such as perfluororubber (FFKM), tetrafluoroethylene / propylene rubber (FEPM), and / or fluorinated silicone rubber (FVMQ). These materials have the advantage of being particularly resistant to chemicals, which is particularly beneficial for wastewater lifting stations due to the fecal matter. Furthermore, the mechanical properties, in particular the deformability and processability of the materials, are particularly suitable for manufacturing the check valve. The elastomer can also be made of other elastic materials.

[0023] According to a further preferred embodiment, an annular space is formed behind the impeller relative to the suction opening, defined by the impeller and the pump housing, in which the check valve is provided. The annular space can extend circumferentially around the motor shaft and / or be formed above the impeller during operation.

[0024] According to another preferred embodiment, the centrifugal pump has a vent channel connected to the check valve, leading away from the pump chamber, and an automatic valve provided on the vent channel, which allows air to escape from the pump chamber and prevents air from entering the pump chamber. The automatic valve allows unhindered passage of air via the vent channel. When the automatic valve is open, air can escape from the pump chamber via the vent opening and the vent channel, which leads to the venting of the pump chamber. When the automatic valve is closed, no air can pass through the automatic valve and enter the pump chamber via the vent opening.

[0025] For the purposes of the invention, an automatic valve is understood in particular to be a valve that opens and closes automatically without auxiliary energy. In other words, the opening and closing process of the automatic valve is not made possible by electrical energy, but by mechanically provided energy. The mechanical energy for opening and closing the automatic valve can be provided by the valve itself and / or by the medium flowing through the automatic valve. The automatic valve is preferably designed such that it opens and / or closes based on pressure differences between a valve inlet side and a valve outlet side. In this case, the valve inlet side is the side of the automatic valve towards the interior of the pump chamber at the vent opening.

[0026] The self-acting valve allows air to escape from the pump chamber, which means the centrifugal pump can properly vent the pump chamber so that fluid can flow into the pump chamber through the suction port after each pumping cycle. Thus, the self-acting valve allows air to flow from the valve inlet side to the valve outlet side. The self-acting valve ensures that the centrifugal pump can pump with high hydraulic efficiency. Furthermore, the self-acting valve prevents air from flowing in the opposite direction, i.e., from outside the pump through the vent port into the pump chamber. In other words, the valve prevents air from flowing from the valve outlet side to the valve inlet side.

[0027] According to a preferred development, the automatic valve is designed as a self-closing flap valve, as a duckbill valve and / or as a tubular valve with two lobes which are placed against one another in the event of backflow and / or are placed against one another in the event of backflow into the pump chamber.

[0028] The self-closing flap valve is preferably at least partially open when the pressure on the valve inlet side corresponds to the pressure on the valve outlet side. It is further preferably possible for a flap of the flap valve to be opened further by the air passing from the valve inlet side to the valve outlet side when the pump is vented and / or by the fluid passing through as a leakage flow during operation of the pump. If, for example, when the pump is operated in the right-hand characteristic curve range, i.e. with a low delivery head and large volume flows of the fluid to be pumped, a situation arises in which the pressure on the valve inlet side is lower than on the valve outlet side, the volume flow is briefly reversed, which leads to the flap valve closing. The flap valve preferably has a dimensional rigidity such that the flap valve opens completely when the pressure upstream and downstream of the flap valve is the same.The self-closing flap valve has the advantage that it is very robust due to its simple design and can be produced without great effort.

[0029] The duckbill valve is preferably a check valve made of elastic material, the shape of which resembles a duck's beak. The end of the duckbill valve corresponding to the valve inlet side preferably has a shape corresponding to the vent opening. The other end of the duckbill valve, i.e. the end corresponding to the valve outlet side, preferably has a flattened shape. The duckbill valve is preferably designed such that it allows unrestricted air flow from the pump chamber through the vent opening. If, however, a flow reversal occurs, so that air briefly flows from outside the pump through the vent opening into the pump chamber, the valve closes and thus prevents the backflow of both fluid, possibly contaminated with solids, and air into the pump chamber.The duckbill valve has the advantage that it closes even at very small pressure differences between the valve inlet and outlet sides and has a very short response time.

[0030] The tubular valve with two lobes preferably has a tubular shape at one end corresponding to the valve inlet side and two lobes at one end corresponding to the valve outlet side. The lobes are preferably two opposing lobe-like end pieces of the hose jacket. The tubular valve is preferably closed by the lobes of the tubular valve coming together in the event of backflow, thus closing a cross-section of the hose. The lobes remain together in the event of backflow, and the cross-section is closed, so that the tubular valve prevents air from flowing into the pump chamber when the pressure conditions are reversed. The tubular valve has the advantage that it responds even with very small pressure differences between the valve inlet side and the valve outlet side and closes the cross-section very quickly.

[0031] Centrifugal pumps are generally suitable for pumping any fluid. Due to their robustness against solids and chemicals, they are particularly suitable for use as submersible dirty water and / or wastewater pumps. Submersible dirty water and / or wastewater pumps are used primarily for pumping contaminated water, for example, from floods, flooded excavations, laundry rooms, muddy pits, biotopes and / or garden ponds, from drainage shafts, and in basements, and especially for pumping water with various levels of contamination, such as stones, mud, debris, or feces. The proposed application ensures quiet operation and reliable ventilation of the pump chamber of the submersible dirty water and / or wastewater pump.In addition, the centrifugal pump can also be used for heating with radiators, radiator heating, underfloor heating, ceiling cooling, water circulation in a drinking water system or a drinking water system with a storage charging system, whereby the above list is not exhaustive, but may include other types of systems not mentioned here.

[0032] Furthermore, the object is achieved by a lifting system comprising a collecting tank and a centrifugal pump as described above, wherein the suction opening of the centrifugal pump faces the interior of the collecting tank. In principle, it is possible for the collecting tank of the lifting system to have an opening that corresponds to the pump housing. The opening of the collecting tank can be closed by applying the centrifugal pump to the opening, wherein the suction opening of the centrifugal pump advantageously faces the interior of the collecting tank.

[0033] Alternatively, it is possible for at least part of a container wall of the collecting container to be formed by the pump housing having the suction opening. In this case, the container wall can be shaped such that it forms a lower part of an at least two-part pump housing. The opening in the container wall is therefore the suction opening of the centrifugal pump. The venting channel preferably leads away from the venting opening to an outer side of the centrifugal pump, which is preferably also formed by the container wall.

[0034] According to a preferred development of the invention, a drive motor of the centrifugal pump is arranged at least partially outside the collecting tank. It has proven advantageous, particularly with regard to the maintenance of the lifting system, for the drive motor to be arranged at least partially outside the collecting tank. Preferably, the drive motor is positioned entirely outside the collecting tank.

[0035] Further embodiments and advantages of using the centrifugal pump and / or the lifting system will become apparent to the person skilled in the art in analogy to the centrifugal pump described above. Short description of the drawings

[0036] The invention is explained in more detail below with reference to the attached drawings using preferred embodiments.

[0037] The drawings show Fig. 1 is a schematic view of a centrifugal pump in a lifting station according to a preferred embodiment of the invention, and Fig. 1 is a further schematic view of the centrifugal pump in the lifting station according to the preferred embodiment of the invention. Detailed description of the implementation examples

[0038] Fig. 1 and 2 show a schematic sectional view of a centrifugal pump 10 in a lifting system 12 according to a preferred embodiment of the invention, which can be used as a dirty water and / or waste water submersible pump.

[0039] The centrifugal pump 10 has a pump housing 16 forming a pump chamber 14. An impeller 18 is arranged within the pump chamber 14. The impeller 18 is connected to a drive motor 24 of the centrifugal pump 10 via a motor shaft 22 extending in the axial direction. The pump housing 16 has a suction opening 26 concentric with the axis of the motor shaft 22, through which a fluid can flow into the pump chamber 14. Captured by the rotational movement of the impeller 18, the fluid is conveyed into a discharge nozzle 28 (shown only schematically). The suction opening 26 of the centrifugal pump 10 is located at the lowest point of the pump housing 16, and the axial direction of the motor shaft 22 corresponds to the vertical direction.

[0040] Furthermore, the pump housing 16 of the centrifugal pump 10 has a vent opening behind the impeller 18 in relation to the suction opening 26, which is designed in the form of a check valve 52. In the centrifugal pump 10 in Figure 1The check valve 52 is located at the highest point of the pump chamber 14 and above the height at which the impeller 18 is attached to the motor shaft 18. The check valve 52 is designed to close in response to the fluid and, when opened, to allow air to escape from the pump chamber 14, as described below.

[0041] The lifting system 12 further comprises a collecting tank 36, which can be connected to the centrifugal pump 10. To connect the centrifugal pump 10 to the collecting tank 36, a tank wall 38 of the collecting tank 36 has an opening that is designed to correspond to the pump housing 16. In the preferred embodiment here, the centrifugal pump 10 and the collecting tank 36 are connected such that the suction opening 26 of the centrifugal pump 10 faces an interior of the collecting tank 36. Specifically, a part of the tank wall 38 is formed by the pump housing 16 having the suction opening 26. The tank wall 38 is shaped such that it forms a lower part of the at least two-part pump housing 16.

[0042] The previously mentioned check valve 52 is provided behind the impeller 18 in relation to the suction opening 26 in an annular space 20 which is delimited by the impeller 18 and the pump housing 16 and through which the motor shaft 22 passes centrally. Specifically, the check valve 52 is designed as a check flap made of a buoyant, rubber-like material, in particular a fluorinated elastomer or rubber, and is attached to the pump housing 16 on its underside relative to the impeller 18. Thus, when the fluid in the pump chamber 14 rises, the check valve 52 pivots from its in Fig. 1 shown open position to the one in Fig. 2 shown closed position. Alternatively, the check valve 52 can be designed as a flap valve and / or a ball valve.

[0043] The check valve 52 is followed by a vent channel 50, which leads away from the annular space 20 in a horizontal direction in this case and is defined opposite the check valve 52 by an automatic valve 32. The automatic valve 32 allows air to escape from the pump chamber 14 while preventing air from entering the pump chamber 14. The automatic valve 32 is designed as a duckbill valve or tubular valve with two lobes that engage one another in the event of backflow and / or are positioned against one another in the event of backflow into the pump chamber 14.

[0044] The check valve 52 has an upper circular part, the diameter of which corresponds to the diameter of the vent channel 50. The upper circular part is attached to a lower, thicker part via a middle part of comparatively smaller thickness, with the three parts being constructed as a single piece. The latter lower part is attached to the pump housing, for example, by means of a screw connection or adhesive bond. Since the middle part is thinner than the other two parts, the middle part allows the pivoting of the flap-like check valve 52 between the open position and the closed position. When unloaded, the check valve 52 tends to move toward the open position. However, if the air pressure and / or the fluid in the pump chamber 14 rises above a threshold value, particularly in the annular space 20, the air pressure and / or the fluid causes the check valve 52 to close.

[0045] The described embodiments are merely examples which can be modified and / or supplemented in many ways within the scope of the claims. List of reference symbols

[0046] Centrifugal pump 10 Lifting system 12 Pump room 14 Pump housing 16 balance bike 18 Annular space 20 Motor shaft 22 drive motor 24 suction opening 26 pressure nozzle 28 valve 32 Collection container 36 container wall 38 ventilation duct 50 Check valve 52

Claims

1. A centrifugal pump (10) for conveying a fluid, comprising a pump housing (16) forming a pump chamber (14), an impeller (17) provided in the pump chamber (14) for conveying the fluid, a suction opening (26) provided in the pump housing (16) for suctioning the fluid through the impeller (18) into the pump chamber (14), and a non-return valve (52), which is provided in the pump housing (16) downstream of the impeller (18) relative to the suction opening (26) and closes owing to the fluid entering the pump chamber and / or from an air pressure prevailing in the pump chamber (14) and, when open, lets air out of the pump chamber (14), wherein the non-return valve (52) is made of a floating material and is fastened to the pump housing (16) at its end closest to the impeller.

2. The centrifugal pump (10) according to the preceding claim, wherein the non-return valve (52) is designed as a non-return flap, a flap valve, and / or a ball check valve.

3. The centrifugal pump (10) according to any one of the preceding claims, wherein the non-return valve (52) is designed to close when the fluid rises in the pump chamber (14).

4. The centrifugal pump (10) according to any one of the preceding claims, wherein the non-return valve (52) is made of a plastics material, an elastomer, a fluorinated elastomer, or rubber.

5. The centrifugal pump (10) according to any one of the preceding claims, wherein an annular space (20) which is delimited by the impeller (18) and the pump housing (16) and in which the non-return valve (52) is provided is formed downstream of the impeller (18) relative to the suction opening (26).

6. The centrifugal pump (10) according to any one of the preceding claims, comprising a venting duct (50) which is connected to the non-return valve (52) and leads away from the pump chamber (14) and a self-activating valve (32) which is provided on the venting duct (50), allows the air to escape from the pump chamber (14) and prevents air from penetrating into the pump chamber (14).

7. The centrifugal pump (10) according to the preceding claim, wherein the self-activating valve (32) is designed as a self-closing flap valve, a duckbill valve, and / or a tubular valve comprising two flaps, which press against one another in the event of a return flow and / or are pressed against one another in the event of backpressure in the pump chamber (14).

8. Use of a centrifugal pump (10) according to any one of the preceding claims as a dirty-water and / or wastewater immersion pump.

9. A pumping system (12) comprising a collection container (36) and a centrifugal pump (10) according to any one of the preceding centrifugal pump claims, wherein the suction opening (26) of the centrifugal pump (10) faces an interior of the collection container (36).

10. The pumping system (12) according to the preceding claim, wherein at least part of a container wall (38) of the collection container (36) is formed by the pump housing (16) comprising the suction opening (26).

11. The pumping system (12) according to any one of the preceding pumping system claims, wherein a drive motor (24) of the centrifugal pump (10) is arranged outside the collection container (36) at least in part.

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