Magnetic coupling pump arrangement comprising a can, and method for producing the can
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- KSB SE & CO KGAA
- Filing Date
- 2024-07-03
- Publication Date
- 2026-05-27
AI Technical Summary
Conventional magnetic coupling pump arrangements face issues with eddy current losses and reduced torque transfer due to thick containment shells, leading to inefficiencies and potential leakage, especially when handling dangerous media, as existing solutions either incur high costs or compromise safety and efficiency.
The containment shell is designed with a large number of obliquely arranged elevations and channel-like cavities to minimize eddy current losses and enhance leak detection, allowing for improved safety and efficiency without compromising stability, using a 3D printing process for production.
This design significantly reduces eddy current losses and heat dissipation, enhances leak detection, and ensures increased safety by preventing medium leakage into hazardous areas, while maintaining the containment shell's stability and reducing material costs.
Smart Images
Figure EP2024068679_23012025_PF_FP_ABST
Abstract
Description
[0001] Description
[0002] Magnetic coupling pump arrangement with containment shell and method for producing the containment shell
[0003] The invention relates to a magnetic coupling pump assembly comprising an interior space formed by a pump housing of the pump assembly, a containment shell with a central longitudinal axis, which hermetically seals a chamber enclosed by it from the interior space formed by the housing, an impeller shaft rotatably driven about a rotational axis, an impeller arranged at one end of the impeller shaft, an inner rotor arranged at the other end of the impeller shaft, and an outer rotor arranged on a drive shaft and interacting with the inner rotor. The invention further relates to a method for producing a containment shell of such a magnetic coupling pump assembly.
[0004] Such sealless pumps are used in particular for pumping dangerous or toxic media in order to prevent leakage, since, depending on the medium, even small quantities of the pumped medium can have life-threatening consequences.
[0005] In sealless pumps, especially magnetically driven pumps, the containment shell is the weak point, as it is designed with minimal wall thickness due to power loss and torque transmission. The problem with conventional containment shells is that their condition cannot be monitored, or only to a limited extent. If, for example, impurities are present in the pumped medium, the containment shell can be worn through, and the potentially hazardous medium can flow into the lantern or the bearing support of the outer rotor.
[0006] Typically, or in conventional solutions, a leakage monitor in the form of a level gauge is installed in the lantern / bearing support area. The problem here is that at least the area in the lantern and the bearing support is contaminated and poses a potential hazard. Furthermore, with such solutions, leakage of the pumped medium through the bearing cannot be ruled out. Therefore, a secondary protective layer cannot be assumed here.
[0007] A secondary protective enclosure can be achieved, for example, by using a second containment shell, which is mounted above the first and is statically sealed. The area between the containment shells can be monitored using various sensors.
[0008] There are currently two variants for using a second containment shell. The use of a metallic containment shell as the primary protective shell in conjunction with a ceramic containment shell mounted above it as the secondary protective shell is known from EP 0 286 822 A2. The problem here is the resulting overall thickness of the two containment shells, as ceramic shells require a greater wall thickness to withstand the pressure. This variant does not result in any additional eddy current losses. However, the problem is that with increasing wall thickness the transmittable torque decreases compared to a single-walled containment shell. To compensate for this, larger magnetic couplings must be installed, which, in conjunction with the more expensive ceramic containment shell, results in high costs. In addition, ceramic is a brittle material that can fail suddenly under mechanical stress.
[0009] The second variant is the use of two containment shells mounted one above the other, as known from WO 2014 / 032816 A1. Here, the resulting intermediate gap is monitored by sensors, as in the previous variant. The problem here is that eddy currents are induced in a metallic / conductive material / containment shell by the magnetic coupling, which are dissipated in the form of heat due to the material resistance. The increased eddy current losses and thus the lower efficiency of the pump are the first negative aspect. The second negative point is that the heat generated in the second containment shell can only be transferred with difficulty or to a limited extent to the inner containment shell, where the heat is transferred to the pumped medium. This leads to the outer containment shell heating up even more, which can cause expansion and grinding of the outer rotor.On the other hand, the high temperatures limit the usability of the magnetic drive pump, as high surface temperatures negatively impact explosion protection (ATEX classes). For these reasons, double-walled metal containment shells are considered impractical and of only limited use.
[0010] One approach to solving the problems listed above is known from WO 2020 / 212250 A1, in which a containment shell for a magnetic coupling is equipped with a cylindrical, one-piece shell region and a base region adjoining a first end of the shell region, wherein at least the shell region has an inner wall and an outer wall enclosing the inner wall, wherein the inner and outer walls are spaced apart from one another in the radial direction by a gap, and the inner wall is integrally connected to the outer wall by a plurality of webs.
[0011] The object of the present invention is to provide a pump arrangement, in particular a magnetic coupling pump arrangement, in which the eddy current losses in the containment shell are minimized without reducing the stability of the containment shell.
[0012] The object of the invention is achieved by providing the outer surface of the containment shell, in particular the base body and base, with a plurality of elevations, which reduce eddy current losses and reduce the heating of the containment shell. It has proven particularly advantageous if the elevations are arranged at least partially at an angle. The angled arrangement of the elevations further reduces the resulting losses and temperatures.
[0013] In a further embodiment, channel-like cavities extend through the elevations, allowing the containment shell arranged on the housing or on a component assigned to the housing, e.g. the housing cover, to be tested for leaks. The cavities can have a defined internal pressure, i.e. overpressure or underpressure. The cavities can be under a vacuum or filled with a gas. If parts of the elevations are damaged, the outside of the containment shell is damaged and a sensor monitoring the cavities detects that the vacuum in the cavities no longer exists or that the gas has escaped from the cavities. If the inside of the containment shell is damaged, the sensor detects that the channels are filled with the pumped medium. In both cases, the pump can be shut down.
[0014] In both cases, no pumped fluid has yet leaked into the lantern area. This represents a significantly increased level of safety for such magnetic-drive pump arrangements. The raised areas and cavities extend both in the area of the base body and in the area of the containment shell.
[0015] Advantageously, the shape of the cavities essentially corresponds to the shape of the elevations, with the elevations or cavities being triangular, elliptical, circular, semi-elliptical, semicircular, trapezoidal, or having another polygonal configuration. The geometry, adapted to the respective requirements, significantly reduces the resulting losses and temperatures.
[0016] The elevations are designed in a screw-like or spindle-like manner with respect to the center line of the containment shell, whereby the elevations are arranged obliquely with respect to an imaginary line extending parallel to the center longitudinal axis of the containment shell on the outer surface, wherein the elevations and the line enclose an angle in a range from greater than 0° to less than 90°, whereby the powdery material remaining in the cavities during production can be removed from the channels.
[0017] Advantageously, the angle is in a range of 30° to 70°.
[0018] It has proven particularly advantageous when the included angle is between 40° and 55°. This reduces the weight of the containment shell, reduces electromagnetic losses, and improves heat dissipation during operation.
[0019] In a further advantageous embodiment, the inclined elevations are interrupted by a plurality of axially extending elevations, with channel-like cavities extending through the axial elevations and connected to the cavities of the inclined elevations. This further reduces electromechanical losses. Furthermore, during the manufacture of the containment shell, it is possible to easily remove the metal powder remaining in the channel-like cavities during 3D printing.
[0020] In a further advantageous embodiment of the containment shell, the elevations have axially extending sections at at least one of their end regions. The advantage of this is that the cavities in the base body and the base of the containment shell can be better connected.
[0021] In a special embodiment, the inclined elevations extending between the axial sections undergo a reversal of direction approximately in the middle of the containment shell's base body, resulting in a substantially mirrored configuration of the elevations. The advantage of this is that the powder trapped in the cavities during production can be removed from the channels via shorter paths. A method according to the invention provides for the outer surface of the containment shell to be provided with a plurality of elevations.
[0022] In order to realize defined and desired microstructures, the containment shell is preferably manufactured using a process in which the containment shell with the elevations and the cavities is created by the selective action of energetic radiation on powder layers applied in layers.
[0023] Embodiments of the invention are illustrated in the drawings and are described in more detail below.
[0024] Fig. 1 shows the longitudinal section through a magnetic coupling pump arrangement according to the prior art,
[0025] Fig. 2 shows the three-dimensional representation of a first embodiment of the containment shell according to the invention in an enlarged view,
[0026] Fig. 3 shows the side view of the can according to the invention according to Fig. 2,
[0027] Fig. 4 shows a section of the can according to the invention according to Fig. 2,
[0028] Fig. 5 shows a section of the can according to the invention according to another
[0029] Design of the containment shell,
[0030] Fig. 6 shows a section of the containment shell according to the invention according to a further embodiment of the containment shell,
[0031] Fig. 7 shows the side view of the can according to the invention according to a further embodiment,
[0032] Fig. 8 shows a section of the containment shell according to the invention according to Fig. 7 Fig. 9 shows a partial view of a further embodiment of the containment shell,
[0033] Fig. 10 shows a schematic representation of a further embodiment of the containment shell according to the invention and
[0034] Fig. 11 shows a schematic representation of a further embodiment of the containment shell according to the invention.
[0035] Fig. 12 a first view of the cavity contour of the containment shell according to Fig. 1
[0036] Fig. 13 a second view of the cavity contour of the containment shell according to Fig. 1
[0037] Figure 1 shows an example of a pump assembly 1 in the form of a magnetic coupling pump assembly, as is known from the prior art. The pump assembly 1 has a multi-part pump housing 2 of a centrifugal pump, which comprises a hydraulic housing 3 designed as a spiral housing, a housing cover 4, a bearing support lantern 5, a bearing support 6, and a bearing cover 7.
[0038] The hydraulic housing 3 has an inlet opening 8 for sucking in a pumped medium and an outlet opening 9 for expelling the pumped medium. The housing cover 4 is arranged on the side of the hydraulic housing 3 opposite the inlet opening 8. The bearing support lantern 5 is attached to the side of the housing cover 4 facing away from the hydraulic housing 3. The bearing support 6 is attached to the side of the bearing support lantern 5 opposite the housing cover 4. The bearing cover 7 is in turn attached to the side of the bearing support 6 facing away from the bearing support lantern 5.
[0039] A containment shell 10 is attached to the side of the housing cover 4 facing away from the hydraulic housing 3 and extends at least partially through an interior space 11 defined by the pump housing 2, in particular by the housing cover 4, by the bearing support lantern 5, and by the bearing support 6. The containment shell 10 hermetically seals a chamber 12 enclosed by it from the interior space 11. An impeller shaft 13, rotatable about a rotational axis A, extends from a flow chamber 14 defined by the hydraulic housing 3 and the housing cover 4 through an opening 15 provided in the housing cover 4 into the chamber 12.
[0040] An impeller 16 is attached to one end of the impeller shaft 13 located within the flow chamber 14. An inner rotor 17 is arranged within the chamber 12 at the opposite end of the shaft. The inner rotor 17 is equipped with several magnets 18, which are arranged on the side of the inner rotor 17 facing the containment shell 10.
[0041] Between the impeller 16 and the inner rotor 17 there is arranged a bearing arrangement 19 which is operatively connected to the impeller shaft 13 which can be driven to rotate about the axis of rotation A.
[0042] A drive motor (not shown), preferably an electric motor, drives a drive shaft 20. The drive shaft 20, which can be driven rotatably about the axis of rotation A, is arranged essentially coaxially with the impeller shaft 13. The drive shaft 20 extends through the bearing cover 7 and the bearing bracket 6 and is mounted in two ball bearings 21, 22 accommodated in the bearing bracket 6. An outer rotor 24 carrying a plurality of magnets 23 is arranged at the free end of the drive shaft 20. The magnets 23 are arranged on the side of the outer rotor 24 facing the containment shell 10. The outer rotor 24 extends at least partially over the containment shell 10 and interacts with the inner rotor 17 in such a way that the rotating outer rotor 24 also sets the inner rotor 17 and thus the impeller shaft 13 and the impeller 16 in a rotational movement by means of magnetic forces.
[0043] The containment shell 10, shown enlarged in Figures 2 and 3, is intended for installation in the pump assembly 1 shown in Fig. 1 as an example of various magnetic coupling pump assemblies. The containment shell 10 has a substantially cylindrical base body 25 with a central longitudinal axis B arranged substantially coaxially to the axis of rotation A according to Fig. 1. The base body 25 is open on one side and closed on the side opposite the open side by means of a substantially curved base 26. Arranged on the open side is an annular connecting flange 27 which is formed integrally with the base body 25.
[0044] The connecting flange 27 has a plurality of bores 28 extending parallel to the central longitudinal axis B, through which screws (not shown) can be pushed and screwed into corresponding threaded bores in the housing cover 4 according to Fig. 1.
[0045] The base 26 is formed by a substantially spherical segment-shaped dome region 29 and an outer rim region 30 forming the transition region between the base body 25 and the dome region 29.
[0046] As can be seen in conjunction with Fig. 3 and Fig. 4, the base body 25 has an outer surface 31 with a plurality of elevations 32. The outer surface 31 is essentially wave-shaped, each with a plurality of wave peaks 33 and wave troughs 34. The elevations 32 are screw- or spindle-shaped, i.e., the elevations 32 are arranged obliquely with respect to an imaginary line L extending parallel to the central longitudinal axis B on the outer surface 31. In the embodiment shown, the elevations 32 and the line L form an angle α of 45°. The angle α can range from greater than 0° to less than 90°. Preferably, the angle α is in a range from 30° to 70°. Channel-like cavities 35 extend through the elevations 32.
[0047] While Fig. 4 shows triangular elevations 32 with triangular cavities 35, Fig. 5 shows elliptical elevations 32 with elliptical cavities 35 formed on the outer surface 31 of the containment shell 10. Further configurations of the elevations 32 are possible. These can have a semicircular or semi-elliptical configuration, as shown in Fig. 6, or a trapezoidal or other polygonal configuration. Fig. 7 in conjunction with Fig. 8 shows a further embodiment of the containment shell.
[0048] 10 for use in a magnetic coupling pump arrangement. In the embodiment shown, the inclined elevations 32 formed on the base body 25 are interrupted by a plurality of elevations 32' extending in the axial direction, i.e., parallel to the central longitudinal axis B. Channel-like cavities 35' extend through the axial elevations 32' and are connected to the cavities 35 of the inclined elevations 32. The design of the elevations 32' can correspond to the design of the elevations 32, but it is also conceivable for the elevations 32' to differ from the design of the elevations 32.
[0049] Fig. 9 shows a further variant of the containment shell 10. The obliquely extending elevations 32 run from one elevation 32' extending parallel to the central longitudinal axis B of the containment shell 10 to the next elevation 32' extending parallel to the central longitudinal axis B of the containment shell 10 at a specific angle α with respect to an imaginary line L extending parallel to the central longitudinal axis B on the outer surface 31. The subsequent elevations 32 extending from the elevations 32' are arranged at an angle α' with respect to the line L which essentially corresponds to 360°-α, thereby creating a herringbone-like configuration.
[0050] Fig. 10 schematically shows a further embodiment of the elevations 32 on the outer surface 31 of the containment shell. The elevations 32 can have axially extending sections 38 and 39, respectively, at at least one of their end regions 36, 37, i.e., parallel to the rotational axis A. These sections are also provided with the channel-like cavities described in the previous figures. The shape of the elevations 32 and the cavities can be selected accordingly.
[0051] A further, alternative design of the elevations 32 is shown schematically in Fig.
[0052] 11. The obliquely extending elevations 32 extending between the axial sections undergo a reversal of direction approximately in the middle of the base body 25, such that an essentially mirrored course of the elevations 32 is created. The axial sections 38, 39 of an elevation 32 lie essentially in one plane. It is clear that axial sections can be dispensed with, and the elevations 32 can have an oblique course from their beginning to their end with respect to an imaginary line L, as shown in Fig. 3.
[0053] The described embodiments show that the containment shell is designed as a homogeneous component. It is manufactured using a 3D printing process.
[0054] Fig. 12 in conjunction with Fig. 13 shows the cavity contour or the course of the cavities 35 in the containment shell 10, in particular the surfaces of the cavities according to Fig. 2 and Fig. 3. The metallic material is, so to speak, hidden. It can be seen that an annular space 40 is formed on the side of the base body 25 opposite the open side, from which annular space 40 the cavities 35 extend towards the open side and finally open into a first half-ring-shaped cavity 41 or a second half-ring-shaped cavity 42. A first connecting channel 43 extends from the first half-ring-shaped cavity 41 through the connecting flange 27 shown in Fig. 2. The first connecting channel 43 is also shown in Fig. 1. A second connecting channel 44 extends from the second half-ring-shaped cavity 42 through the connecting flange 27.
[0055] As can be seen from Fig. 13, the first semi-annular cavity 41 has a first ramp-shaped region with a slope 45 and a second ramp-shaped region with a slope 46, which meet at a point 47. The second semi-annular cavity 42 has a first ramp-shaped region with a slope 48 and a second ramp-shaped region with a slope 49, which meet at a point 50.
[0056] The first connecting channel 43 and the second connecting channel 44 are arranged at the lowest point of the cavity 41 and the cavity 42, respectively, when the open side of the containment shell is oriented downwards.
[0057] This makes it possible for the loose powder remaining in the cavities 35, 35', 40, 41 and 42 during production by means of 3D printing to trickle out of these cavities from the area of the bottom 26 via the area of the base body 25 and via the area of the connecting flange 27 and finally via the first connecting channel 43 or the second connecting channel 44, or to be conveyed out of these cavities by blowing out.
Claims
Patent claims 1. Magnetic coupling pump arrangement with - an interior space (11) formed by a pump housing (2) of the pump arrangement, - a containment shell (10) with a central longitudinal axis (B), which hermetically seals a chamber (12) enclosed by it from the interior space (11) formed by the pump housing (2), - an impeller shaft (13) rotatably driven about an axis of rotation (A), - an impeller (16) arranged at one end of the impeller shaft (13), - an inner rotor (17) arranged at the other end of the impeller shaft (13), - an outer rotor (24) arranged on a drive shaft (20) and cooperating with the inner rotor (17), characterized in that the outer circumferential surface (31) of the containment shell (10) is provided with a plurality of elevations (32, 32').
2. Magnetic coupling pump arrangement according to claim 1, characterized in that the outer circumferential surface (31) of the containment shell (10) is provided with a plurality of elevations (32, 32') which are arranged at least partly obliquely.
3. Magnetic coupling pump arrangement according to claim 1 or 2, characterized in that channel-like cavities (35, 35') extend through the elevations (32, 32').
4. Magnetic coupling pump arrangement according to claim 3, characterized in that the shape of the cavities (35, 35') substantially corresponds to the shape of the elevations (32, 32'), wherein the elevations (32, 32') or the cavities (35, 35') are triangular, elliptical, circular, semi-elliptical, semi-circular, trapezoidal or have another polygonal configuration.
5. Magnetic coupling pump arrangement according to one of the preceding claims, characterized in that the elevations (32) are screw-like or spindle-like.
6. Magnetic coupling pump arrangement according to one of the preceding claims, characterized in that the elevations (32) are arranged obliquely with respect to an imaginary line (L) extending parallel to the central longitudinal axis (B) on the outer circumferential surface (31), the elevations 32 and the line L enclosing an angle (α) in a range from greater than 0° to less than 90°.
7. Magnetic coupling pump arrangement according to claim 6, characterized in that the angle (a) lies in a range of 30° to 70°.
8. Magnetic coupling pump arrangement according to claim 6 or 7, characterized in that the angle (a) is 45°.
9. Magnetic coupling pump arrangement according to one of the preceding claims, characterized in that the obliquely extending elevations (32) are interrupted by a plurality of elevations (32') extending in the axial direction.
10. Magnetic coupling pump arrangement according to one of the preceding claims, characterized in that channel-like cavities (35') which are connected to the cavities (35) of the obliquely extending elevations (32).
11. Magnetic coupling pump arrangement according to one of the preceding claims, characterized in that the elevations (32) have axially extending sections (38, 39) on at least one of their end regions (36, 37).
12. Magnetic coupling pump arrangement according to one of the preceding claims, characterized in that the obliquely extending elevations (32) extending between the axial sections undergo a reversal of direction approximately in the middle of the base body (25) such that a substantially mirrored course of the elevations (32) is present.
13. Method for producing a containment shell of a magnetic coupling pump, characterized in that the outer circumferential surface (31) of the containment shell (10) is provided with a plurality of elevations (32, 32').
14. The method according to claim 13, characterized in that the containment shell (10) is produced by a method in which the containment shell with the elevations (32, 32') and the cavities (35, 35') is produced by selective exposure of energetic radiation to powder layers applied in layers.