EP3945218B1 - Centrifugal pump - Google Patents

Description

Technical area

The invention relates to a centrifugal pump with a motor housing with a drive motor arranged in the motor housing and a pump housing arranged on the motor housing forming a pump chamber with an impeller arranged in the pump chamber and drivable by the drive motor for conveying a fluid, wherein the motor housing is coaxially surrounded on the outside by a cooling jacket forming a cooling jacket chamber, which cooling jacket chamber has a cooling jacket inlet opening out of the pump chamber into the cooling jacket chamber, through which fluid conveyed by the impeller can flow into the cooling jacket chamber. The invention further relates to a use of the centrifugal pump as a dirty water and/or waste water submersible pump or in a lifting system.

Background of the invention

Waterproof submersible motors are used in particular in dirty water and/or sewage submersible pumps or in lifting systems. In contrast to standard motors, waterproof submersible motors of this type do not have simple active cooling using an air flow. The power loss of the submersible motor is usually dissipated by passive cooling via the surrounding medium. Installing the submersible motor in air therefore requires short operating times or power outputs or a relatively high use of active materials such as copper or iron. In order to generate economical solutions under these aspects, oil-filled motors, oil-filled motors with internal cooling or dry motors with external, closed circulation cooling or open sheath flow cooling are used.

With jacket flow cooling, the entire volume flow or only a partial volume flow is introduced into the cooling jacket to cool the motor, but this can lead to problems and in particular to a reduction in operational reliability. This is because solids conveyed through the cooling jacket space can lead to sedimentation in the cooling jacket space over time, particularly in the case of waste water pumps.

The CN 105 673 574 A describes a liquid-cooled low-noise multistage centrifugal pump. The liquid-cooled low-noise multistage centrifugal pump includes a pump body, a liquid-cooled motor, a pump shaft encased with a shaft sleeve and a spacer ring, a journal bearing connected outside the shaft sleeve in an encasement mode, a coupling connected to the pump shaft, a motor that drives the pump shaft to rotate through the coupling, an impeller connected on the pump shaft in an insert mode, and a plurality of guide vanes fixed by steel bands and matched in a mutual cascade connection mode.

The EN 10 2005 034 341 A1 describes a submersible motor pump with a pump housing, an impeller arranged therein and an electric drive motor connected to it, on the motor housing of which a cooling jacket is arranged, whereby a fluid conveyed by an impeller flows through the cooling jacket. The impeller is provided with a known relief device in the form of a pressure-side throttle gap arranged on a smaller impeller diameter and pressure relief of the relief space enclosed by the throttle gap takes place via the space of the cooling jacket.

The JP 2001 304 197 A describes a submersible pump which can prevent a reduction in cooling efficiency by ensuring a good passage of the coolant by preventing deposition of small solid foreign matters such as sand mixed with a natural water such as rainwater and a muddy water serving as a cooling medium on a hollow coolant passage part. To this end, a hollow coolant passage is provided so as to surround a motor frame on a motor casing, with an inlet for the coolant opened at an upper portion of the hollow coolant passage and an outlet for the coolant opened at a lower end. The inlet of the coolant is communicated with a rear space of an impeller via a coolant supply pipe provided on the outside of the hollow coolant passage and a coolant supply passage provided on a casing cover.

Description of the invention

Based on this situation, it is an object of the present invention to provide a centrifugal pump which is characterized by improved operational reliability.

The object of the invention is solved by the features of the independent claim. Advantageous embodiments are specified in the subclaims.

• das Motorgehäuse koaxial außen von einem einen Kühlmantelraum ausbildenden Kühlmantel umgeben ist, welcher Kühlmantelraum einen aus dem Pumpenraum in den Kühlmantelraum mündenden Kühlmanteleinlass aufweist, durch welchen von dem Laufrad gefördertes Fluid in den Kühlmantelraum einströmbar ist, und
• der Kühlmantelraum einen innerhalb des Pumpengehäuses und außerhalb des Pumpenraums mündenden Kühlmantelauslass aufweist, durch welchen das Fluid aus dem Kühlmantelraum ausströmbar ist.

Accordingly, the object is achieved by a centrifugal pump with a motor housing with a drive motor arranged in the motor housing and a pump housing arranged on the motor housing forming a pump chamber with an impeller arranged in the pump chamber and drivable by the drive motor for conveying a fluid, wherein

• the motor housing is coaxially surrounded on the outside by a cooling jacket forming a cooling jacket chamber, which cooling jacket chamber has a cooling jacket inlet opening from the pump chamber into the cooling jacket chamber, through which fluid conveyed by the impeller can flow into the cooling jacket chamber, and
• the cooling jacket chamber has a cooling jacket outlet opening inside the pump housing and outside the pump chamber, through which the fluid can flow out of the cooling jacket chamber.

An essential point of the invention is therefore that the fluid after flowing through the cooling jacket space after cooling the drive motor does not flow into the pump space, for example not into a space behind the impeller and/or an edge side space of the impeller as known from the prior art, but outside the pump space. A cooling jacket return flow therefore takes place back in front of a suction mouth of the centrifugal pump, for example into a suction basket of the centrifugal pump in front of the pump space. The proposed return of the fluid as a cooling volume flow from the pump space effectively minimizes the entry of solids into the edge side space and thus significantly increases the operational reliability of the centrifugal pump, since blocking of the impeller is reduced in this way. At the same time, sedimentation of the cooling jacket space over time is reduced or even completely avoided, since solids conveyed through the cooling jacket space can be conveyed through the cooling jacket outlet, in particular into the suction mouth of the centrifugal pump.

Especially in the case of sewage pumps, safe operation with a cooling jacket chamber cooling system is only guaranteed if an air-water mixture is always returned to the pump chamber. If the return of the fluid as a cooling medium is designed in such a way that only air is initially pressed into the pump chamber after the drive motor is switched on, a fluid flow can break off. This break off occurs particularly when the air in the cooling jacket is compressed by the incoming fluid and then suddenly escapes into the pump chamber. The proposed solution eliminates this problem by ensuring that the fluid from the cooling jacket does not escape into the pump chamber but rather outside it. In other words, the fluid return is designed in such a way that the impeller is always supplied with sufficient fluid and a sudden ingress of air is avoided.

A centrifugal pump is generally a fluid machine that uses rotary motion and dynamic forces to pump liquids, primarily as a fluid. In addition to a tangential acceleration of the fluid, also called the medium, centrifugal force occurring in radial flow is used for pumping, so that centrifugal pumps are also called centrifugal pumps. During regular operation of the centrifugal pump, the motor housing is preferably arranged above the pump housing, fixed to it and/or designed as a single piece. The fluid preferably comprises water or another liquid medium such as waste water. The fluid can comprise solids such as contaminants of any kind, in particular feces, sediment, dirt, sand, or even smaller pieces of wood, brushwood, textiles or rags or the like. The impeller is preferably arranged completely in the pump chamber.

The motor housing and/or the cooling jacket can have a cylindrical shape which can taper away from the pump housing. The motor housing and/or the cooling jacket space is preferably made of metal, in particular of stainless steel, and/or the pump housing is made of plastic. The cooling jacket space preferably surrounds the motor housing at least partially and in particular completely, particularly preferably along a jacket surface of the motor housing. The cooling jacket inlet is preferably arranged in a pressure outlet of the pump housing and/or in the pump housing in such a way that a rotational movement of the impeller allows fluid to flow into the cooling jacket space and/or pumps it. The cooling jacket space is preferably closed in a fluid-tight manner except for the cooling jacket inlet and the cooling jacket outlet.

According to a preferred development, the cooling jacket outlet opens into an intake area of the impeller in front of the pump chamber and/or the cooling jacket outlet opens on the upstream side in front of the pump chamber. The fluid is therefore not returned behind the impeller as in the designs known from the prior art, but in any case outside of the pump chamber having the impeller, in particular as proposed by the further development in front of the pump chamber, which eliminates or at least noticeably reduces the risk of the fluid flow breaking off.

According to another preferred development, the cooling jacket inlet is arranged in an overpressure area of the pump chamber and/or the cooling jacket outlet is arranged in a negative pressure area of the pump housing. The overpressure area is preferably provided behind the impeller in the so-called edge side space of the pump chamber. The negative pressure area is preferably provided in an intake area of the pump housing in front of the pump chamber. Due to a differential pressure between the cooling jacket inlet, at which overpressure is created due to the rotational movement of the impeller, and the cooling jacket outlet, with a lower negative pressure, fluid flows through the cooling jacket from the cooling jacket inlet to the cooling jacket outlet to cool the drive motor.

According to a further preferred embodiment, the pump housing has a suction basket provided on the upstream side in front of the pump chamber, wherein the cooling jacket outlet is covered by the suction basket. The suction basket can be designed as a grid-like design and be provided below a base plate of the pump housing, be part of the base plate and/or the pump housing and/or be designed in one piece with them. In this way, the suction basket is located in the suction area and/or vacuum area of the centrifugal pump.

According to another preferred development, the centrifugal pump has a pipe provided in the cooling jacket space, which on the one hand opens into the cooling jacket outlet at a first end of the cooling jacket space, extends axially parallel to an axis of the impeller to a second end of the cooling jacket space opposite the first end, and on the other hand opens into the cooling jacket space at the second end. The pipe is preferably bent at the second end to form a circular flow, for example with a radius of 28 mm over 15, 30 or 45 degrees or more. The pipe is preferably made of metal, in particular stainless steel. The first end preferably forms the cooling jacket outlet. The pipe preferably has a diameter of 8, 10 or 12 mm. In regular operation, the first end preferably faces the motor housing at a lower edge of the cooling jacket and the second end preferably faces away from the motor housing at an upper edge of the cooling jacket. The cooling jacket outlet and pipe can be formed as one piece. The cooling jacket outlet can also be inserted into the pump housing, for example by milling, into which the pipe can be inserted.

Furthermore, a cooling jacket inlet pipe can be provided in the cooling jacket space, which on the one hand opens into the cooling jacket inlet at a first end of the cooling jacket space, extends axially parallel to an axis of the impeller to a second end of the cooling jacket space opposite the first end, and on the other hand opens into the cooling jacket space at the second end. The cooling jacket inlet and cooling jacket inlet pipe can be formed as one piece. The cooling jacket inlet can also be inserted into the pump housing, for example by milling, into which the cooling jacket inlet pipe can be inserted. According to a further preferred embodiment, the pipe has a first vent opening at the first end in the cooling jacket space. Solids of greater density and/or weight can be discharged through the first vent opening. Furthermore, the operational reliability of the centrifugal pump is improved by the first vent opening, since air cannot suddenly escape into the pump housing due to the first vent opening. The first vent opening preferably has a diameter of 3, 4, 5, 6, 7 or 8 mm. The tube further preferably has two first vent openings provided opposite one another at the first end. The first vent opening can be designed as a transverse bore.

According to the invention, the pipe is bent at the second end, extends parallel to the axis back to the first end and opens into the cooling jacket space at the first end. The pipe is preferably bent at the second end by 180 degrees or approximately 180 degrees. At the first end, the pipe is preferably bent to form a circular flow, for example with a radius of 28 mm over 15, 30, 45 or 60 degrees. The pipe can also extend approximately parallel to the axis, for example pivoted by a few degrees, back to the first end.

According to a further preferred embodiment, a second vent opening is provided in the curved area. Solids of lower density and/or weight can be removed through the second vent opening. Furthermore, the cooling jacket can be reliably vented through the second vent opening and it can be prevented that the cooling jacket is not sucked dry via the cooling jacket outlet when the fluid level in the cooling jacket drops. The second vent opening preferably has a diameter of 3, 4, 5, 6, 7 or 8 mm. The second vent opening can be designed as a transverse bore. The tube also preferably has two second vent openings provided opposite one another.

According to another preferred development, the centrifugal pump has a second pipe provided in the cooling jacket space, which opens into the cooling jacket outlet on the one hand and into the cooling jacket space on the other hand at the first end of the cooling jacket space. The second pipe is preferably designed as one piece with the cooling jacket outlet. For this purpose, two cooling jacket outlets can be provided, which can be arranged next to one another. The second pipe can also be designed so that it can be inserted into the cooling jacket outlet. The second pipe can be used to remove particles of greater density in the lower region of the cooling jacket. The second pipe also improves the operational reliability of the centrifugal pump, since the second pipe prevents air from suddenly escaping into the pump housing. The second pipe is preferably designed to be shorter than the first pipe. The second pipe preferably has a diameter of 8, 10 or 12 mm.

According to a preferred development, the centrifugal pump is designed as a submersible pump or as a lifting system. A submersible pump is understood to be a portable or stationary centrifugal pump that is immersed in the liquid to be pumped as a fluid. Submersible pumps are used in particular in water supply and wastewater disposal. Submersible pumps are used, among other things, to pump heavily contaminated fluids, such as wastewater or dirty water in particular, but also for other fluid media with a high solids content such as stones, rubble and the like. The impeller shapes used in particular are free-flow impellers, single-channel impellers, multi-channel impellers, diagonal impellers, helical impellers and propeller impellers. Lifting systems are understood to be automatically operating systems that drain wastewater that accumulates below a backflow level in a backflow-safe manner or pump it to a higher level. The wastewater lifting system is usually installed at the lowest point in a basement, either freely or in a pit, or in a shaft, a so-called pump sump.

The object of the invention is further achieved by using a centrifugal pump as described above as a dirty water and/or waste water submersible pump or in a lifting system. In addition, the centrifugal pump can also be used for a drinking water system or other fluid-conveying applications, whereby types of systems not mentioned here may be included. Dirty water and/or sewage submersible pumps are used in particular for pumping out dirty water, for example from floods, in flooded construction pits, in laundry rooms, in muddy pits, in biotopes and/or from garden ponds, from drainage shafts and in cellars, and in particular for pumping fluids such as water with various degrees of contamination such as stones, mud or rubble.

In particular, the entry of stones as solids into the edge side space can lead to frequent blocking of the impeller in dirty water pumps known from the state of the art and significantly reduce operational reliability. The proposed use ensures a high level of efficiency of the dirty water and/or waste water submersible pump in the long term, as the aforementioned problem is eliminated, as is the case with a lifting system. In a lifting system, the proposed solution makes it possible to dispense with the vent lines known from the state of the art outside the cooling jacket and to vent the cooling jacket using the proposed solution.

Short description of the drawings

The invention is explained in more detail below with reference to the accompanying drawings using preferred embodiments.

• Fig. 1 eine schematische teilgeöffnete Seitansicht einer Kreiselpumpe als Schmutzwasserpumpe gemäß einem bevorzugten Ausführungsbeispiel der Erfindung,
• Fig. 2 eine Schnittansicht eines unteren Teils der Kreiselpumpe gemäß Fig. 1 ,
• Fig. 3 links eine schematische teildursichtige Kreiselpumpe als Teil einer Hebeanlage sowie rechts eine Schnittansicht der Kreiselpumpe als Teil einer Hebeanlage gemäß einem weiteren bevorzugten Ausführungsbeispiel der Erfindung, und
• Fig. 4 eine Schnittansicht eines unteren Teils einer Kreiselpumpe als Abwasserpumpe gemäß einem weiteren bevorzugten Ausführungsbeispiel der Erfindung.

In the drawings show

• Fig.1 a schematic partially opened side view of a centrifugal pump as a dirty water pump according to a preferred embodiment of the invention,
• Fig.2 a sectional view of a lower part of the centrifugal pump according to Fig.1 ,
• Fig.3 on the left a schematic partially transparent centrifugal pump as part of a lifting system and on the right a sectional view of the centrifugal pump as part of a lifting system according to a further preferred embodiment of the invention, and
• Fig.4 a sectional view of a lower part of a centrifugal pump as a sewage pump according to another preferred embodiment of the invention.

Detailed description of the implementation examples

Fig.1 shows a schematic partially opened side view in the transverse direction of a centrifugal pump as a dirty water pump according to a preferred embodiment of the invention.

The centrifugal pump has a motor housing 1 made of stainless steel, which is placed on a pump housing 2 made of plastic. In the motor housing 1 there is a drive motor 3, in Fig. 3 shown, which has a Fig. 3 The vertical shaft shown drives an impeller 5 provided in a pump chamber 4 formed by the pump housing 2 for conveying water as a fluid. The cylindrical motor housing 1 is coaxially surrounded on the outside of its jacket surface by a cylindrical cooling jacket 7 forming a cooling jacket chamber 6. The cooling jacket 7 is shown open in the middle of the drawing plane in order to allow a partial view into the cooling jacket chamber 6.

On the one hand, a tubular cooling jacket inlet 8 is provided in the cooling jacket chamber 6, which opens from the pump chamber 4 into the cooling jacket chamber 6. The cooling jacket inlet 8 opens into a so-called edge side chamber 9 in the pump chamber 4 in an overpressure area of the pump chamber 4, so that the impeller pumps fluid through the cooling jacket inlet 8 into the cooling jacket chamber 6 when it rotates. The tubular cooling jacket inlet 8 continues via a stainless steel pipe 10 from the pump chamber 4, initially vertically upwards in the plane of the drawing into the pump chamber 4, and bends in the cooling jacket chamber 6 towards its end with a radius of 28 mm, bent over 60°, to form a circular flow.

On the other hand, a cooling jacket outlet 11 is provided for returning the fluid thus conveyed into the cooling jacket chamber 6, which extends in the cooling jacket chamber 6 parallel to the stainless steel pipe 10 or the tubular cooling jacket inlet 8. The cooling jacket outlet 11 opens inside the pump housing 2 but outside the pump chamber 4, namely in a suction area of the impeller 4 on the upstream side and thus in a negative pressure area in front of the pump chamber 4. A suction basket 12 provided on the upstream side in front of the pump chamber 4 covers the cooling jacket outlet 11, as can also be seen from the a sectional view in the longitudinal direction of a lower part of the centrifugal pump according to Fig.1 showing Fig.2 is evident. Through the By returning the fluid out of the pump chamber 4, the entry of solids into the peripheral side chamber 9 is minimized and the operational reliability of the centrifugal pump is improved.

As particularly on Fig.1 As can be seen, a pipe 13, also made of stainless steel, is provided in the cooling jacket space 6, which opens into the cooling jacket outlet 11 at a first end of the cooling jacket space 6 or continues from the cooling jacket outlet 11 into the cooling jacket space 6. The pipe 13 extends in the cooling jacket space 6 axially parallel to an axis of the impeller 4 in the plane of the drawing vertically upwards to a second end of the cooling jacket space 6 opposite the first end and opens into the cooling jacket space 6 at the second end. The pipe 13 also bends at the second end with a radius of 28 mm over 60 degrees. At the first end, the pipe 13 has a first vent opening 14 with a diameter of 6 mm for removing solids of greater density and/or weight.

Fig.3 shows on the left a schematic, partially transparent centrifugal pump as part of a lifting system and on the right a sectional view of the centrifugal pump as a lifting system according to another preferred embodiment of the invention. As can be seen in the figure on the left, the pipe 13 is bent by 180 degrees at the second end and extends parallel to the axis back to the first end. At the first end, the pipe 13 opens into the cooling jacket space 6 and again bends over 60 degrees with a radius of 28 mm. A second vent opening 15 is provided in the bent area for removing solids of low density and/or weight.

Finally, Fig.4 a sectional view of a lower part of a centrifugal pump as a waste water pump according to a further preferred embodiment of the invention. In addition to the pipe 13, a second pipe 16 is provided in the cooling jacket space, which opens at the first end of the cooling jacket space 6 on the one hand into the cooling jacket outlet 11 and on the other hand into the cooling jacket space 6. The second pipe 16 extends parallel to the pipe 13, but is shorter. A respective cooling jacket outlet 11 is provided for the pipe 13 and the second pipe 16. Sufficient fluid is pumped back into the pump housing 2 through the shorter second pipe 16, so that the risk of a sudden interruption of the fluid flow in the pump space 4 is averted. The stainless steel pipe, the pipe 13 and the second pipe 16 each have a diameter of 8 mm.

The described return of the fluid from the pump chamber 4 reduces the entry of solids into the edge side chamber 6, which improves the operational reliability of the centrifugal pump, since blocking of the impeller 5 by solids that would otherwise be conveyed towards the impeller 5 is reduced. At the same time, sedimentation of the cooling jacket chamber 6 over time is reduced or even completely avoided, since solids conveyed through the cooling jacket chamber 6 can be conveyed through the cooling jacket outlet 11, in particular into a suction mouth of the centrifugal pump.

List of reference symbols

Engine housing

1

Pump housing

2

Drive motor

3

Pump room

4

Wheel

5

Cooling jacket space

6

Cooling jacket

7

Cooling jacket inlet

8th

Marginal side space

9

Stainless steel pipe

10

Cooling jacket outlet

11

Suction basket

12

Pipe

13

First vent opening

14

Second vent opening

15

Second pipe

16

Claims (9)

1. A centrifugal pump with a motor housing (1) having a drive motor (3) arranged in the motor housing (1) and a pump housing (2) arranged on the motor housing (1) and forming a pump chamber (4) with an impeller (5) arranged in the pump chamber (4) and drivable by the drive motor (3) for conveying a fluid, wherein

   the motor housing (1) is coaxially surrounded on the outside by a cooling jacket (7) forming a cooling jacket chamber (6),

   the cooling jacket chamber (6) has a cooling jacket inlet (8) opening from the pump chamber (4) into the cooling jacket chamber (6), through which fluid conveyed by the impeller (5) can flow into the cooling jacket chamber (6), and

   the cooling jacket chamber (6) has a cooling jacket outlet (11) which opens inside the pump housing (2) and outside the pump chamber (4) and through which the fluid can flow out of the cooling jacket chamber (6), wherein

   the centrifugal pump has a pipe (13) provided in the cooling jacket chamber (6), which pipe opens on the one hand at a first end of the cooling jacket chamber (6) into the cooling jacket outlet (11), extends axially parallel to an axis of the impeller (5) as far as a second end of the cooling jacket chamber (6) opposite the first end, the pipe (13) is bent at the second end, extends axially parallel back to the first end and opens into the cooling jacket chamber (6) in the region of the first end.
2. The centrifugal pump according to the preceding claim, wherein the cooling jacket outlet (11) opens in a suction region of the impeller (5) upstream of the pump chamber (4) and/or the cooling jacket outlet (11) opens upstream of the pump chamber (4).
3. The centrifugal pump according to any one of the preceding claims, wherein the cooling jacket inlet (8) is arranged in an overpressurized region of the pump chamber (4) and/or the cooling jacket outlet (11) is arranged in a negative pressurized region of the pump housing (2).
4. The centrifugal pump according to any one of the preceding claims, wherein the pump housing (2) has a suction strainer (12) provided upstream of the pump chamber (4) and the cooling jacket outlet (11) is covered by the suction strainer (12).
5. The centrifugal pump according to any one of the preceding claims, wherein the pipe (13) has a first vent opening (14) at the first end of the cooling jacket chamber (6).
6. The centrifugal pump according to any one of the preceding claims, wherein in a second vent opening (15) is provided in the bent region.
7. The centrifugal pump according to any one of the preceding claims, with a second pipe (16) provided in the cooling jacket chamber (6), which pipe opens at the first end of the cooling jacket chamber (6) into the cooling jacket outlet (11) on the one hand and into the cooling jacket chamber (6) on the other hand.
8. The centrifugal pump according to any one of the preceding claims, wherein the centrifugal pump is configured as a submersible pump or as a lifting system.
9. Use of a centrifugal pump according to any one of the preceding centrifugal pump claims as waste water and/or waste water submersible pump or in a lifting system.

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