A centrifugal pump assembly

Abstract

Described and claimed is a centrifugal pump assembly comprising a motor housing and a pump housing. The motor housing encapsulates an electric motor driving a drive shaft that is rotatable about a drive axis and further includes a coolant line for guiding pump liquid past the electric motor. The pump housing defines a pump chamber with one or more impellers which are attached to the drive shaft. The drive axis extends through a coolant divider formed between the pump chamber and the motor housing defining an inlet opening for receiving pump liquid from the pump chamber and an outlet opening for dispensing pump liquid into the pump chamber. A radial distance of the inlet opening from the drive axis exceeds a radial distance of the outlet opening from the drive axis. The coolant divider further defines a feed conduit enabling a flow of pump liquid from the inlet opening to the coolant line and a return conduit enabling a flow of pump liquid from the coolant line to the first outlet opening.

Description

[0001] Description

[0002]

[0001] The present invention is directed to a centrifugal pump assembly comprising a motor housing and a pump housing. The motor housing encapsulates an electric motor driving a drive shaft that is rotatable about a drive axis. The pump housing defines a pump chamber. One or more impellers are located in the pump chamber. The one or more impellers are attached to the drive shaft and are rotatable about the drive axis.

[0003]

[0002] Electric motors used for driving the impellers of pump assemblies are oftentimes cooled using fans blowing air around the motor. However, the fan increases the outer dimensions of the centrifugal pump assembly and the operation of the fans creates noise. In other examples, the electric motors are cooled using an external liquid coolant medium. The coolant is driven by a dedicated coolant pump through coolant lines in the electric motor. Liquid cooled motors are commonly deemed less noisy due to the lack of an open fan. However, the need for a dedicated coolant pump increases the outer dimension of the pump assemblies. Also, the design of the pump and its maintenance are more complex due to the additional coolant pump.

[0004]

[0003] In view of the above, it can be considered an object of the present invention to provide a centrifugal pump assembly with an improved way of cooling the electric motor of the pump assembly.

[0005]

[0004] The object is solved by a centrifugal pump assembly according to claim 1 . Preferred embodiments of the pump assembly are the subjectmatter of the dependent claims.

[0005] The invention is directed to a centrifugal pump assembly comprising a motor housing and a pump housing. The motor housing encapsulates an electric motor driving a drive shaft that is rotatable about a drive axis. The motor housing includes a first coolant line for guiding pump liquid past the electric motor. The first coolant line extends between a feed section and a return section. The pump housing defines a pump chamber. One or more impellers are located in the pump chamber and attached to the drive shaft and are rotatable about the drive axis. The drive axis extends through a coolant divider delimiting the pump chamber towards the motor housing. The coolant divider defines at least a first inlet opening for receiving pump liquid from the pump chamber and at least a first outlet opening for dispensing pump liquid into the pump chamber. A radial distance of the first inlet opening from the drive axis exceeds a radial distance of the first outlet axis from the drive axis. The coolant divider further defines a first feed conduit enabling a flow of pump liquid from the first inlet opening via a first feed opening of the coolant divider to the feed section of the first coolant line and a return conduit enabling a flow of pump liquid from the return section of the first coolant line via a first return opening of the coolant divider to the first outlet opening.

[0006]

[0006] In other words, the present invention is directed to a centrifugal pump assembly that uses pump liquid from the pump chamber for cooling the electric motor. To this end, the motor housing which encapsulates the electric motor includes at least one first coolant line. The first coolant line is provided for directing pump liquid past the electric motor so that the electric motor is cooled. The coolant line may have a variety of different shapes. For example, the first coolant line may be essentially U- shaped or may be spiraling around the motor or parts thereof.

[0007]

[0007] The electric motor may, for example, be a permanent magnet synchronous motor. The rotor of the electric motor is attached to a drive shaft that rotates about a drive axis. The electric motor could be a dryrunning electric motor or a wet-running electric motor. During operation of the pump the drive axis may, for example, extend vertically or horizontally depending on the configuration of the pump.

[0008]

[0008] The drive shaft of the electric motor is attached to one or more impellers depending on the number of stages of the pump assembly. For example, the pump assembly may be configured as a single stage centrifugal pump where only a single impeller is attached to the drive shaft. Alternatively, the pump may also be configured as a multi-stage centrifugal pump with multiple impellers attached to the drive shaft. In case the pump is configured as a multi-stage pump, all impellers but the impeller of the final stage are surrounded by an impeller chamber. Each impeller chamber comprises guide vanes directing the flow of pump fluid created by the respective impeller back towards the drive shaft and towards the next impeller stage. The flow of pump fluid generated by the impeller of the final stage may, for example, be redirected by guide vanes towards a pressure-side outlet of the pump assembly.

[0009]

[0009] Between the pump chamber and a rotor chamber of the motor housing a coolant divider is formed. The object of the coolant divider is to redirect or retrieve pump liquid from the pump chamber so that it can be used as coolant in the first coolant line. The coolant divider may be formed as a separate element that is placed between the pump housing and the motor housing but could also be part of, for example, a top cover of the pump housing which closes the pump housing off towards the motor.

[0010]

[0010] The coolant divider has at least one inlet for taking up pump liquid from the pump chamber and at least one outlet through which pump liquid can be fed back into the pump chamber. The first inlet opening is connected via a first feed conduit and a first feed opening to a feed section of the first coolant line. Hence, the feed section through which the pump liquid flows into the first coolant line is connected via the first inlet opening, the first feed conduit and the first feed opening to the pump chamber. Preferably, the first inlet opening is formed in a surface that is directly in contact with the pump liquid in the pump chamber. After flowing through the first coolant line, the pump liquid can flow back into the pump chamber via the first return opening, the first return conduit and the first outlet opening. Again, the first outlet opening is preferably directly in contact with the pump liquid that is circulating or flowing in the pump chamber so that there are no additional conduits between the first outlet opening and the pump chamber.

[0011]

[0011] The flow of the pump liquid through the coolant divider and the first coolant line is driven by the distance of the respective openings from the drive axis. Concretely, the first inlet opening is positioned further away in a radial direction from the drive axis as the first outlet opening. Since the pressure in the pump liquid increases with the distance from the drive axis, positioning the inlet opening further away from the drive axis as the outlet opening results in a pressure difference in the pump liquid between the inlet opening and the outlet opening. Hence, the pressure of the pump liquid is higher at the position of the inlet opening than at the position of the outlet opening.

[0012]

[0012] The pressure difference drives the flow of pump liquid through the coolant divider and the coolant line. Thus, a coolant flow is achieved without having to install an additional pump for the coolant medium. Further, by placing the coolant divider between the impeller chamber and the motor housing it is also directly adjacent to the final stage impeller of the centrifugal pump. Here, the highest pressure is provided by the pump and already comparatively small differences in the radial distances from the drive axis may cause a sufficiently high flow of pump liquid or coolant.

[0013] The rate of flow of the pump liquid through the coolant line can be controlled by the difference in the radial distance of the respective openings from the drive axis. The greater the difference in the distance, the higher the pressure difference and, therefore, the higher the flow of pump liquid through the coolant line. Thus, when a pump assembly is dimensioned for a specific purpose and the approximate temperature of the pump liquid as well as the maximum required flow rates and pump head are known, the necessary amount of coolant can be provided by selecting the position of the inlet openings and the outlet openings in the coolant divider.

[0013]

[0014] For the sake of completeness, it is noted that for two openings being at different radial distances from the drive axis, the two openings do not have to be aligned in a radial direction. Rather, the two openings can be placed at arbitrary angles about the drive axis. They do not even have to be formed in the same radial plane, where a radial plane extends perpendicular to the drive axis.

[0014]

[0015] In a preferred embodiment, the motor housing further includes a second coolant line for guiding pump liquid past the electric motor. The second coolant line extends between a feed section and a return section. The coolant divider defines a second inlet opening for receiving pump liquid from the pump chamber and a second outlet opening for dispensing pump liquid into the pump chamber. A radial distance of the second inlet opening from the drive axis exceeds a radial distance of the second outlet opening from the drive axis. The coolant divider further defines a second feed conduit enabling a flow of pump liquid from the second inlet opening via a second feed opening of the coolant divider to the feed opening a second coolant line and a second return conduit enabling a flow of pump liquid from the return section of the second coolant line via a second return opening of the coolant divider to the second outlet opening.

[0016] Thus, in the preferred embodiment a second coolant line is provided through the electric motor. Having a second coolant line may have a variety of advantages such as a better distribution of the coolant in the motor and, thus, a more homogenous cooling thereof. However, this may also be achieved by a differently shaped coolant line. The second coolant line and the connection to the pump liquid in the pump chamber provided by the coolant divider are formed in essentially the manner as the connection to the first coolant line. Therefore, for the sake of brevity a repetition of the previous description of the details is omitted.

[0015]

[0017] Preferably, the second outlet opening is formed by the first outlet opening and the second return conduit is at least partially formed integrally with the first conduit. The second inlet opening is formed, however, separately from the first inlet opening and the second feed conduit is preferably formed separately from the first feed conduit. Hence, in the preferred embodiment there are two separate inlet openings, one for each coolant line but there is only one combined outlet openings for both coolant lines. The two inlet openings are connected via separate feed conduits to the respective coolant lines. On the return side of the coolant circuit, the return flows from the two coolant lines are combined in the coolant divider at a point where the two return conduits merge into a single return conduit which terminates in a single outlet opening.

[0016]

[0018] By keeping the inlet openings and inlet conduits separate, the inflow or feed of the coolant can be better controlled. It is, in particular, ensured that the intended amount of pump liquid flows into each of the coolant lines since the amount is largely driven by the pressure difference between the radial position of the respective inlet opening and the outlet opening. If the two coolant lines were supplied with pump liquid through a single inlet opening, the flow characteristics in the at least partly combined feed conduit would strongly affect the distribution of the pump liquid flow towards the coolant lines. This could result in an unintended distribution of coolant among the coolant lines and, therefore, negatively affect the motor temperature.

[0017]

[0019] On the return side this problem does not exist and combining the two return flows in a single return conduit in the coolant divider simplifies the design of the coolant divider which is preferential.

[0018]

[0020] In a preferred embodiment the first inlet opening and / or the second inlet opening extend generally perpendicular to the drive axis. In other words, the first inlet opening and, if present, the second inlet opening are formed in a surface that extends in a plane which is perpendicular to the drive axis.

[0019]

[0021] In another preferred embodiment, the first outlet opening and / or the second outlet opening are formed in a cylindrical surface extending parallel to the drive axis and facing towards the drive axis. Thus, the first outlet opening and, if available, the second outlet opening do not extend perpendicular to the drive axis as the inlet openings in the preferred embodiment. Instead, the outlet openings face towards the drive axis and are formed on a surface that extends circumferentially about the drive axis.

[0020]

[0022] In a preferred embodiment, the first feed opening and the first return opening are located at a same radial distance from the drive axis. Alternatively or additionally, the second feed opening and, if available, the second return opening are located at the same radial distance from the drive axis. Hence, in the preferred embodiment the distance of the first feed opening and the corresponding first return opening where the coolant divider is connected to the first coolant line are formed at the same radial distance from the drive axis. The difference in radial distance and position from the drive axis as compared to the inlet opening and outlet opening is bridged by the respective feed conduits and return conduits in the coolant divider. The same applies to the position of the second feed opening and the second return opening.

[0021]

[0023] By placing the feed opening and the return opening at the same radial distance from the drive axis, a symmetrical arrangement of the coolant line in the pump motor can be achieved. This is preferable as it allows for a homogeneous cooling of the electric motor. Further, the minimum distance of the coolant line from the drive axis is limited by the fact that the coolant line needs to run outside of the rotor chamber. Also, it may be beneficial to guide the coolant line sufficiently far away from the drive axis that the coolant does not only reduce the temperature of the motor but could also be used to cool the housing of the motor and parts connected thereto.

[0022]

[0024] In a preferred embodiment, the coolant divider supports a shaft seal surrounding the drive shaft. The shaft seal prevents liquid from the pump chamber from leaking along the drive shaft into the rotor chamber of the electric motor. Placing the shaft seal inside the coolant divider allows for more compact design of the centrifugal pump assembly, since the length of the centrifugal pump assembly along the drive axis can be reduced as compared to a configuration in which the shaft seal would be placed in a separate plane since the latter would increase the distance between the pump chamber and the motor.

[0023]

[0025] In another preferred embodiment the pump chamber comprises a suction opening opposite the coolant divider. The suction opening is aligned with the drive axis.

[0024]

[0026] In another preferred embodiment the coolant divider is formed as a separate part mounted between the pump chamber and a rotor chamber, where a rotor of the electric motor is located. Hence, in the preferred embodiment, the coolant divider is provided separately from other parts of the centrifugal pump assembly and, in particular, the pump housing defining the pump chamber and the motor housing. Providing the coolant divider as a separate part has the benefit that the coolant divider can be easily adapted to different required flows of coolant. By changing the difference in the radial distance of the first and second inlet opening from the drive axis and of the first and second outlet opening from the drive axis, the coolant flow can be adapted. Hence, by simply exchanging the coolant divider, the cooling flows can be modified without having to change other parts of the pump. This may be required for adapting the pump for different temperatures of the pump liquid or for when the pump is used in different operating scenarios. Thus, pump can be easily reconfigured if needed.

[0025]

[0027] It is further preferred, if the coolant divider comprises a first part and a second part. The first part faces the pump chamber and defines at least the first inlet opening and at least the first outlet opening. The second part faces the motor housing and defines at least the first feed opening and the first return opening. At least the first feed conduit and the second return conduit are formed between the first part of the cooling divider and the second part of the cooling divider.

[0026]

[0028] Splitting the cooling divider into two parts has several benefits. First, when moulding the coolant divider the feed conduits and / or return conduits can be easily molded. Further, going back to the benefit of having a separate part as a cooling divider in the first place, in case the cooling divider is made up from a first part and a second part as in the present preferred embodiment, it is sufficient for modifying the flow of pump fluid to only exchange the first part of the cooling divider as only the first part of the cooling divider defines the position of the inlet openings and the outlet openings.

[0029] In a preferred embodiment, the first coolant line and / or the second coolant line extend through a stator of the electric motor. Alternatively or additionally, it is preferred for the first cooling line and the second cooling line to be formed integrally with parts of the motor housing. It is in particular preferred, that the first coolant line and / or the second coolant line are moulded or cast integrally with parts of the motor housing. However, the coolant lines could also be formed as separated parts installed in a motor housing. For example, the motor housing could be made from aluminum using high pressure die casting and the first and / or second coolant line could be made from stainless steel pipes integrated into the aluminum mold. Hence, in the preferred embodiment the coolant lines are an integral part of the motor design and extend right through the stator. The coolant lines can, in particular, be directly integrated into the parts of the stator which support the stator windings.

[0027]

[0030] In a preferred embodiment, the pump assembly further comprises an electronics housing at least partially surrounding electronics unit. The first coolant line is further configured for guiding a pump liquid past a heat sink of the electronics unit. The heat sink is preferably formed by the motor housing. Hence, in the preferred embodiment, the at least first cooling line is not only used for cooling the electric motor itself but also the electronics unit. To this end, the electronics unit of the pump assembly is preferably mounted or attached to the motor housing which thus serves as a heat sink.

[0028]

[0031] Finally, it is preferred for the flow of the pump liquid from the first inlet opening to the first outlet opening via a first coolant line to be solely driven by a pressure differential in the pump fluid in the pump chamber between the position of the first inlet opening and the first outlet opening. Likewise, it is preferred for the flow of the pump liquid from the second inlet opening to a second outlet opening via the second coolant line being solely driven by a pressure differential in the pump liquid in the pump chamber between the position of the second inlet opening and the second outlet opening. Thus, in the preferred embodiment, it is emphasized that only the pressure differential in the pump chamber between the inlet openings and the respective outlet opening is used for driving the flow of pump fluid through the coolant lines. This precludes the use of any additional means fordriving the flow of pump fluid through the coolant lines.

[0029]

[0032] The present will subsequently be described in more detail with reference to the drawings which show an exemplary embodiment of a centrifugal pump assembly and an exemplary embodiment of a coolant divider, wherein

[0030] Fig. 1 . shows a perspective view of an exemplary embodiment of a centrifugal pump assembly,

[0031] Fig. 2 shows a side view of the exemplary embodiment of Fig. 1 ,

[0032] Fig. 3 shows a cut through the exemplary embodiment of Fig. 2 along the line - B,

[0033] Fig. 4 shows another cut through the exemplary embodiment of Fig. 2 along the line A-A,

[0034] Fig. 5 shows a side view of an exemplary embodiment of a cooling divider,

[0035] Fig. 6 shows a bottom view of the exemplary embodiment of Fig. 5,

[0036] Fig. 7 shows a cut through the embodiment of Fig. 5 along the line

[0037] B / B,

[0038] Fig. 8 shows a cut through the embodiment of Fig. 5 along the line A-A,

[0039] Fig. 9 shows a cut through the embodiment of Fig. 6 along the line C-C, and

[0040] Fig. 10 shows a cut through the motor housing and the electronics housing of the exemplary embodiment of Fig. 1 .

[0033] Figs. 1 and 2 show an exemplary embodiment of a pump assembly 1 comprising a pump housing 3, a motor housing 5 and an electronics housing 7. The pump housing 3 surrounds a plurality of impellers (not shown in Figs. 1 and 2). It defines a suction-side inlet or suction opening 9 where the fluid to be pressurized by the pump assembly 1 is ingested into the pump housing 3. The pressurized pump fluid is ejected from the pump housing 3 through a pressure-side outlet 1 1 . The suction-side inlet 9 is coaxially aligned with a drive axis 13 (only shown in Fig. 2) of the electric motor located inside the motor housing 5. The pressure-side outlet 1 1 extends perpendicular to the suction-side inlet 9 and radially away from the drive axis 13. Hence, the pump housing 3 is used for an end-suction pump assembly 1. However, the pump housing 3 could also be configured differently with the suction-side inlet 9 pointing radially away from the drive axis 13 so that the pump assembly 1 is an in-line pump. Also, other configurations are possible.

[0041]

[0034] Figs. 3 and 4 show two sectional cuts through the pump assembly 1 of Figs. 1 and 2. The cut shown in Fig. 3 is taken along the line B-B depicted in Fig. 2, whereas the cut shown in Fig. 4 is taken along the plane A-A shown in Fig. 2. The drive axis 13 extends horizontally in the plane of the drawing shown in Fig. 4.

[0042]

[0035] The pump assembly 1 is a centrifugal pump assembly 1 with three pump stages. The three impellers 15a, 15b, 15c of the three impeller stages are located in a pump chamber 21 of the pump housing 3. All three impellers 15a, 15b, 15c are mounted on a drive shaft 17 that is rotatably driven by the electric motor 19 about the drive axis 13. The impellers 15a, 15b of the first two pump stages are further surrounded by impeller chambers 23a, 23b which are placed inside the pump chamber 21. The impeller chambers 23a, 23b comprise a guide surface 25a, 25b redirecting the flow of a pump fluid accelerated by the respective impeller 15a, 15b towards the impeller 15bm 15c of the subsequent pump stage. The flow of a pump fluid created by the final impeller 15c is redirected by a guide surface 27 formed at the pump top 29 towards the pressure-side outlet 1 1 of the pump housing 3. The pump top 29 delimits the pump chamber 21 at an opposing end from the suction-side inlet 9. Each of the guide surfaces 23a, 23b, 27 comprises guide vanes 31 a formed for redirecting the respective spiraling pump flows.

[0043]

[0036] The drive shaft 17 is attached to a rotor 33 of an electric motor 19. It is further supported by two bearings 35 located in the pump housing 5. The electric motor 19 further comprises a stator 37 and two coolant lines 39a, 39b for guiding pump fluid from the pump chamber 21 as coolant through the pump housing 5. In Figs. 3 and 4 only a first coolant line 39a of the two coolant lines 39a, 39b is visible. Each coolant line 39a, 39b comprises a feed section 41 through which pump liquid flows from the pump chamber into the coolant line 39a, 39b. The coolant lines 39a, 39b further comprise a return section 43 through which the pump liquid serving as coolant flows back from the coolant line 39a, 39b into the pump chamber 21. The feed section 41 and the return section 43 are in fluid communication in a part not shown in Figs. 3 and 4. As can be seen in particular in Fig. 3, the first coolant line 39a is integrated into the motor housing 5 when the motor housing 5 is produced. The second coolant line 39b is formed identically. The motor housing 5 could, for example, be formed from aluminum using high pressure die casting and the coolant lines 39a, 39b could be formed by molding stainless steel pipes into the aluminum.

[0044]

[0037] Pump fluid is supplied to the coolant lines 39a, 39b from the pump chamber 21 using a coolant divider 45. The coolant divider 45 is positioned or arranged between the pump housing 3 and the motor housing 5. In other words, the coolant divider 45 is placed between the pump chamber 21 and a rotor chamber 47 in which the rotor 33 of the electric motor 19 is placed. Details of the coolant divider will now be described with reference to Figs. 5 to 9.

[0045]

[0038] The coolant divider 45 comprises a first part 49 and a second part 51 . The first part 49 is placed adjacent to the pump chamber 21 in the pump housing 3. The second part 51 is placed adjacent to the rotor chamber 47 in the motor housing 5. The first part 49 and the second part 51 are separated from each other along a plane that extends perpendicularly to the drive axis 13. The first and second part 49, 51 are tightly attached to one another and to the motor housing 5 using screws 53 which are only shown in Fig. 4.

[0046]

[0039] The coolant divider 45 comprises two inlet openings 55a, 55b which are formed in a surface 57 that extends generally perpendicular to the drive axis and is in direct contact with pump liquid in the pump chamber 21 during operation of the pump assembly 1. The two inlet openings 55a, 55b thus also extend generally perpendicular to the drive axis 13 and the flow through the inlet openings 55a, 55b is about parallel to the drive axis 13. The two inlet openings 55a, 55b can be seen best in Fig. 6. Each of the inlet openings 55a, 55b is connected to a feed conduit 59a, 59b that is formed between the first part 49 and the second part 51 of the coolant divider 45.

[0047]

[0040] The feed conduits 59a, 59b each terminate in a feed opening 61 a, 61 b where the coolant divider 45 is connected to the respective feed sections 41 of the coolant lines 39, 39b. The coolant divider 45 thus comprises a first flow part formed by the first inlet opening 55a, the first conduit 59a and the first feed opening 61 a for supplying the first coolant line 39a with coolant in the form of pump liquid. Similarly, the coolant divider 45 comprises a second flow part formed by the second inlet opening 55b, the second feed conduit 59b and the second feed opening 61 b for suppling the second coolant line 39b with coolant in the form of pump liquid. By forming a separate supply flow path or feed flow path for each of the coolant lines 39a, 39b it is ensured that each coolant line is supplied with all pump fluid that is pushed through the respective inlet opening 55a, 55b from the pump chamber 21 into the feed conduits 59a, 59b.

[0048]

[0041] On the return side, the coolant flows from the coolant lines 39a, 39b via two return openings 63a, 63b back into the coolant divider 45. The return openings 63a, 63b merge into a combined return conduit 65 which is in fluid communication with the pump chamber 21 via a combined outlet opening 67. The outlet opening 67 is formed in a cylindrical surface 69 which extends circumferentially about the drive axis 13. Thus, any pump fluid flowing back from either of the coolant lines 39a, 39b is combined in the single return conduit 65, which, thus, serves both as a first return conduit 65 and second return conduit 65. The fluid is then dispersed vertically through the outlet opening 67 into the pump chamber 21 . Due to the position of the outlet opening 67, the returning coolant or pump fluid flows towards the drive axis 13.

[0049]

[0042] The flow of the pump fluid or coolant through the coolant lines 39a, 39b is driven by a pressure differential that is caused by the radial distance of the inlet openings 55a, 55b and the outlet opening 67 from the drive axis 13. Since the inlet openings 55a, 55b are further away from the drive axis 13 than the outlet opening 67, the pressure in the spiraling flow of pump fluid created by the final impeller 15c is higher at the position of the inlet openings 55a, 55b than at the position of the outlet opening 67. The pressure difference generates a sufficiently high flow of a pump fluid through the feed conduits 59a, 59b, the coolant lines 39a, 39b and the return conduit 65. By changing the relative radial distance of the inlet openings 55a, 55b and the outlet opening 67 from the drive axis 13 the flow of pump fluid can be adapted for different temperatures of the pump fluid or different requirements in the coolant flow. Thus, by replacing the coolant divider 45 the flow of coolant can be adapted to different requirements.

[0050]

[0043] Since the coolant divider 45 is advantageously formed from two different parts 49, 51 , it is even sufficient to replace only the first part 49 in which the inlet openings 55a, 55b and the outlet opening 67 are formed to change the pressure difference between the inlet openings 55a, 55b and the outlet opening 67 and, thereby, the flow of pump fluid through the coolant lines. The second part 51 which provides, in particular, the connection to the coolant lines 39a, 39b does not have to be modified. Also, it is not necessary to adapt the coolant lines 39a, 39b or their position in case the coolant flow needs to be adapted.

[0051]

[0044] It should be noted that a shaft seal 71 preventing flow of pump fluid the pump chamber 21 to the rotor chamber 47 is supported in the coolant divider 45. Also, for the completeness it is pointed out that the pump top 29 is not closed and its end facing towards the electric motor 19 so that the pump fluid can reach the surface 57 of the coolant divider 45 and also flow back from the outlet opening 67 to the pump chamber 21.

[0052]

[0045] Finally, Figure 10 shows a cut through the motor housing 5 and the electronics housing 7 of the pump assembly 1 shown in Figure 1 . The drive axis 13 extends through the cut shown in Figure 10. However, the drive shaft and the coolant divider are not depicted.

[0053]

[0046] As can be seen in Figure 10, the coolant lines 39a, 39b are integrally formed in the motor housing 5. Thus, the coolant running through the coolant lines 39a, 39b essentially cools the motor housing 5 and the motor housing 5 takes up the heat generated by the electric motor 19.

[0047] The motor housing 5 further comprises a projection 73 protruding into the electronics housing 7. The projection 73 forms a heat sink 75 for an electronics module 77 located inside the electronics housing 7. The heat sink 75 dissipates the heat generated inside the electronics hous- ing 7. The coolant line 39a guides pump liquid directly past the projection 73 forming the heat sink 75 and, thus, supports cooling the electronics module 77.

[0054] Reference numerals pump assembly pump housing motor housing electronics housing suction-side inlet, suction opening pressure-side outlet drive axis impeller drive shaft electric motor pump chamber impeller chamber guide surface guide surface pump top guide vanes rotor bearing stator coolant line feed section return section coolant divider rotor chamber first part second part screws inlet opening surface feed conduit feed opening return opening return conduit outlet opening cylindrical surface shaft seal projection heat sink electronics module

Claims

Claims1. A centrifugal pump assembly (1 ) comprising a motor housing (5) and a pump housing (3), wherein the motor housing (5) encapsulates an electric motor ( 19) driving a drive shaft ( 17) that is rotatable about a drive axis ( 13) and wherein the motor housing (5) includes at least a first coolant line (39a, 39b) for guiding pump liquid past the electric motor (19), the first coolant line (39a, 39b) extending between a feed section (41 ) and a return section (43), wherein the pump housing (3) defines a pump chamber (21 ), wherein one or more impellers (15a, 15b, 15c) are arranged in the pump chamber (21 ), attached to the drive shaft ( 17) and rotatable about the drive axis (13), wherein the drive axis (13) extends through a coolant divider (45) formed between the pump chamber (21 ) and the motor housing (5), the coolant divider (45) defining at least a first inlet opening (55a, 55b) for receiving pump liquid from the pump chamber (21 ) and at least a first outlet opening (67) for dispensing pump liquid into the pump chamber (21 ) , wherein a radial distance of the first inlet opening (55a, 55b) from the drive axis (13) exceeds a radial distance of the first outlet opening (67) from the drive axis (13), and wherein the coolant divider (45) further defines a first feed conduit (59a, 59b) enabling a flow of pump liquid from the first inlet opening (55a, 55b) via a first feed opening (61 a, 61 b) of the coolant divider (45) to the feed section (41 ) of the first coolant line (39a, 39b) and a return conduit (65) enabling a flow of pump liquid from the return section (43) of the first coolant line (39a. 39b) via a first return opening (63a, 63b) of the coolant divider (45) to the first outlet opening (67).

2. Centrifugal pump assembly (1 ) according to claim 1 , wherein the motor housing (5) further includes a second coolant line (39a, 39b) for guiding pump liquid past the electric motor (19), the second coolant line (39a, 39b) extending between a feed section (41 ) and a return section, wherein the coolant divider (45) defines a second inlet opening (55a, 55b) for receiving pump liquid from the pump chamber (21 ) and a second outlet opening (67) for dispensing pump liquid into the pump chamber (21 ), wherein a radial distance of the second inlet opening (55a, 55b) from the drive axis (13) exceeds a radial distance of the second outlet opening (67) from the drive axis (13), and wherein the coolant divider (45) further defines a second feed conduit (59a, 59b) enabling a flow of pump liquid from the second inlet opening (55a, 55b) via a second feed section (41 ) of the coolant divider (45) to the feed opening (61 a, 61 b) of the second coolant line (39a, 39b) and a second return conduit (65) enabling a flow of pump liquid from the return section (43) of the second coolant line (39a, 39b) via a second return opening (63a, 63b) of the coolant divider (45) to the second outlet opening (67).

3. Centrifugal pump assembly (1 ) according to claim 2, wherein the second outlet opening (67) is formed by the first outlet opening (67) and wherein the second return conduit (65) is at least partially formed integrally with the first return conduit (65), while the second inlet opening (55a, 55b) is formed separately from the first inlet opening (55a, 55b) and the second feed conduit (59a, 59b) is formed separately from the first feed conduit (59a, 59b).

4. Centrifugal pump assembly ( 1 ) according to any of the preceding claims, wherein the first inlet opening (55a, 55b) and / or the secondinlet opening (55a, 55b) extend generally perpendicular to the drive axis (13).

5. Centrifugal pump assembly ( 1 ) according to any of the preceding claims, wherein the first outlet opening (67) and / or the second outlet opening (67) are formed in a cylindrical surface (69) extending around the drive axis (13) and facing towards the drive axis (13).

6. Centrifugal pump assembly ( 1 ) according to any of the preceding claims, wherein the first feed opening (61 a, 61 b) and the first return opening (63a, 63b) are located at a same radial distance from the drive axis ( 13), and / or wherein the second feed opening (61 a, 61 b) and the second return opening (63a, 63b) are located at a same radial distance from the drive axis (13).

7. Centrifugal pump assembly ( 1 ) according to any of the preceding claims, wherein the coolant divider (45) supports a shaft seal (71 ) surrounding the drive shaft (17).

8. Centrifugal pump assembly ( 1 ) according to any of the preceding claims, wherein the pump chamber (21 ) comprises a suction opening (9) opposite the coolant divider (45), wherein the suction opening (9) is aligned with the drive axis (13).

9. Centrifugal pump assembly ( 1 ) according to any of the preceding claims, wherein the coolant divider (45) is formed as a separate part mounted between the pump chamber (21 ) and a rotor chamber (47) where a rotor (33) of the electric motor (19) is located.

10. Centrifugal pump assembly (1 ) according to claim 9, wherein the coolant divider (45) comprises a first part (49) and a second part (51 ), wherein the first part (49) faces the pump chamber (21 ) and defines at least the first inlet opening (55a, 55b) and at least the first outlet opening (67), wherein the second part (51 ) faces the motor housing (5) and defines at least the first feed opening (61 a, 61 b) and the first return opening (63a, 63b), and wherein at least the first feed conduit (59a, 59b) and the second return conduit (65) are formed between the first part (49) of the coolant divider (45) and the second part (51 ) of the coolant divider (45).1 1 . Centrifugal pump assembly ( 1 ) according to any of the preceding claims, wherein the first coolant line (39a, 39b) and / or the second coolant line (39a, 39b) extend through a stator (37) of the electric motor (19).

12. Centrifugal pump assembly ( 1 ) according to any of the preceding claims, wherein the first coolant line (39a, 39b) and / or the second coolant line (39a, 39b) are formed integrally with parts of the motor housing (5).

13. Centrifugal pump assembly ( 1 ) according to any of the preceding claims, wherein the pump assembly (1 ) further comprises an electronics housing (7) partially surrounding an electronics module (77), wherein the first coolant line (39a, 39b) is further configured for guiding pump liquid past a heat sink (75) of the electronics module (77), wherein the heat sink (75) is preferably formed by the motor housing (5).

14. Centrifugal pump assembly ( 1 ) according to any of the preceding claims, wherein the flow of pump liquid from the first inlet opening (55a, 55b) to the first outlet opening (67) via the first coolant line(39a, 39b) is solely drive by a pressure differential in the pump fluid in the in the pump chamber (21 ) between the position of the first inlet opening (55a, 55b) and the first outlet opening (67) and / or wherein the flow of pump liquid from the second inlet opening (55a, 55b) to the second outlet opening (67) via the second coolant line (39a, 39b) is solely driven by a pressure differential in the pump fluid in the pump chamber (21 ) between the position of the second inlet opening (55a, 55b) and the second outlet opening (67).

Images