A magnetically coupled pump device equipped with a can, and a method for manufacturing a can.
The innovative can design for magnetically coupled pumps, featuring protrusions and cavities, addresses eddy current losses and leak detection, enhancing efficiency and safety by minimizing heat and preventing leaks.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- KSB SE & CO KGAA
- Filing Date
- 2024-07-03
- Publication Date
- 2026-07-23
AI Technical Summary
Conventional magnetically coupled pumps face issues with eddy current losses and heat generation due to conductive can walls, leading to reduced torque transmission and increased costs, while secondary protective jackets complicate leak detection and pose safety hazards.
The can design incorporates protrusions and channel-type cavities on the outer surface, arranged diagonally or spirally, to minimize eddy current losses and facilitate leak detection through pressure monitoring, using 3D printing for manufacturing.
This design reduces electromagnetic losses, enhances heat dissipation, and improves safety by preventing leaks into the lantern area, ensuring reliable operation and compliance with explosion protection standards.
Smart Images
Figure 2026524696000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a magnetic coupling pump device, comprising an internal chamber formed by a pump casing of the pump device, a can having a longitudinal central axis, the can sealing the chamber surrounded by the can airtightly with respect to the internal chamber formed by the casing, a can, an impeller shaft that can be rotationally driven about a rotation axis, an impeller disposed at one end of the impeller shaft, an internal rotor disposed at the other end of the impeller shaft, and an external rotor disposed on a drive shaft and interacting with the internal rotor. The present invention further relates to a method for manufacturing a can of this type of magnetic coupling pump device.
Background Art
[0002] Such pumps without a shaft seal are used particularly for delivering dangerous or toxic media, and for some media, even a small amount of the delivered media can pose a life-threatening risk, so they are designed to eliminate leaks.
[0003] In the case of pumps without a shaft seal, particularly magnetic coupling pumps, the cans are embodied with the smallest possible wall thickness for power loss and torque transmission, which creates weaknesses. The problem with conventional cans is that their condition can only be monitored within a limited range or not at all. For example, if contaminants are present in the pumped medium, the can may wear and penetrate, allowing the hazardous medium to flow into the "lantern" of the external rotor or the bearing bracket.
[0004] In typical or conventional solutions, a leak monitoring system in the form of a level meter is mounted in the lantern / bearing bracket area. The problem here is that at least this area within the lantern and bearing bracket becomes contaminated, posing a potential hazard. Furthermore, such solutions cannot prevent leakage of the pumped medium through the bearing assembly. Therefore, in this case, proceeding based on a secondary protective jacket is not feasible.
[0005] A secondary protective jacket is achieved, for example, by using a second can mounted on top of the first can and statically sealed. The gap between the cans can be monitored using various sensors.
[0006] When using the second can, there are currently two variations. It is known from Patent Document 1 that a metal can is used as the primary protective jacket, and a ceramic can mounted on top of it is used as the secondary protective jacket. Here, the resulting total thickness of the two cans becomes an issue because the ceramic can requires a greater wall thickness to withstand the pressure. In this variation, there are no additional eddy current losses. However, the problem is that with increasing wall thickness, the transmittable torque decreases compared to a single-wall can. To compensate for this, a larger magnetic coupling must be installed, which results in higher costs in combination with the more expensive ceramic can. Furthermore, ceramic is a brittle material and can suddenly break under mechanical load.
[0007] A second modification, as known from Patent Document 2, involves using two cans mounted vertically. Here, as with the previous modification, the gap formed is monitored by a sensor.
[0008] The problem here is that eddy currents are induced in the metal / conductive material / can by magnetic coupling, and these manifest as heat due to the resistance of the material. Increased eddy current losses, and therefore lower pump efficiency, are the first negative aspects. The second negative is that the heat generated in the second can can be transferred with difficulty, or only to a limited extent, to the inner can where the heat is released to the pumping medium. This leads to the constantly increasing heating of the outer can, which can lead to expansion and friction against the outer rotor. On the other hand, high surface temperatures negatively affect explosion protection (ATEX class), thus limiting the usefulness of magnetically coupled pumps. For these reasons, metal double-walled cans are classified as impractical and usable only in limited applications.
[0009] One approach to solving the problems described above is known from Patent Document 3, in which a can for magnetic coupling comprises a cylindrical, integrated shell region and a bottom region adjacent to a first end of the shell region, wherein at least the shell region has an inner wall and an outer wall surrounding the inner wall, the inner and outer walls being separated by a radial gap, and the inner wall being integrally connected to the outer wall by a plurality of webs. [Prior art documents] [Patent Documents]
[0010] [Patent Document 1] European Patent Application Publication No. 0286822 [Patent Document 2] International Publication No. 2014 / 032816 [Patent Document 3] International Publication No. 2020 / 212250 [Overview of the project]
[0011] Herein, the object of the present invention is to provide a pump device, in particular a magnetically coupled pump device, that minimizes eddy current losses within a can without reducing the stability of the can.
[0012] The object of the present invention is achieved by providing numerous protrusions on the outer sides of the can, particularly on the body and bottom, thereby reducing eddy current losses and ensuring that the can is not heated in a concentrated manner.
[0013] It has been found to be particularly advantageous when at least some of the protrusions are arranged diagonally. The diagonal arrangement of the protrusions further reduces the losses and temperatures that occur.
[0014] As a further development, channel-type cavities extend through ribs, thereby allowing cans located on or on components related to the casing, such as the casing cover, to be checked for leaks. The cavities can have a specified internal pressure, i.e., an elevated or reduced pressure. The cavities can be under vacuum or filled with gas. If some of the ribs are damaged, and therefore there is damage to the outside of the can, a sensor monitoring the cavities will detect that the vacuum inside the cavities is no longer present or that gas has leaked out of the cavities. If the inside of the cans is damaged, the sensor will detect that the channels are filled with the medium being delivered. In either case, the pump can be stopped.
[0015] Therefore, in either case, the pumped medium has not yet leaked into the lantern area. This represents a significantly improved level of safety for this type of magnetically coupled pump device. The protrusions and cavities extend into both the body and bottom areas of the can.
[0016] In an advantageous manner, the shape of the cavity substantially corresponds to the shape of the protrusion, and the protrusion and cavity are designed as triangular, elliptical, circular, semi-elliptical, semi-circular, or trapezoidal shapes, or have some other polygonal configuration. The resulting losses and temperatures are significantly reduced by the geometric shape that suits the respective requirements.
[0017] In relation to the can's centerline, the ribs are spiral or spindle-shaped in design, and as a result, the ribs are positioned obliquely to a virtual line extending parallel to the longitudinal central axis of the can on the outer surface, and the ribs and lines form angles in the range of greater than 0° and less than 90°, thereby allowing powdery material remaining in the cavity during manufacturing to be removed from the channel.
[0018] The angle is advantageously in the range of 30° to 70°.
[0019] It has been found to be particularly advantageous when the angle formed is between 40° and 55°. As a result, the weight of the can is reduced, electromagnetic losses are reduced, and heat dissipation during operation is particularly good.
[0020] In another advantageous embodiment, the obliquely extending ribs are interrupted by a number of axially extending ribs, and channel-shaped cavities connected to the cavities of the obliquely extending ribs extend through the axial ribs. This makes it possible to further reduce electromechanical losses and, in addition, makes it possible to remove metal powder remaining in the channel-shaped cavities during 3D printing from the channels in a simple manner during can manufacturing.
[0021] In another advantageous embodiment of the can, the projections have portions that extend axially to at least one of their end regions. The advantage here is that the cavities within the body and bottom of the can can be better connected.
[0022] In one particular embodiment, in this context, it is assumed that diagonally extending ridges extending between axial portions undergo a reversal of direction approximately at the center of the can body, resulting in the presence of a substantially mirrored pattern of ridges. The advantage here is that powder present in the cavity during manufacturing can be removed from the channel via a shorter path.
[0023] The method according to the present invention assumes that a number of protrusions are provided on the outer side surface of the can.
[0024] To obtain the specified desired structure, the cam is preferably manufactured by a method in which a cam having ridges and cavities is manufactured by the selective action of energy radiation on a powder layer applied layer by layer.
[0025] Exemplary embodiments of the present invention are shown in the drawings and will be described in more detail below.
Brief Description of the Drawings
[0026] [Figure 1] It is a longitudinal sectional view through a magnetic coupling pump device according to the prior art. [Figure 2] It is an enlarged view showing a three-dimensional representation of a first embodiment of a cam according to the present invention. [Figure 3] It is a side view of a cam according to the present invention shown in FIG. 2. [Figure 4] It is a detailed view of a cam according to the present invention shown in FIG. 2. [Figure 5] It is a detailed view of a cam according to the present invention according to another embodiment of the cam. [Figure 6] It is a detailed view of a cam according to the present invention according to another embodiment of the cam. [Figure 7] It is a side view of a cam according to the present invention according to another embodiment. [Figure 8] It is a detailed view of a cam according to the present invention shown in FIG. 7. [Figure 9] It is a partial view of another embodiment of the cam. [Figure 10] It is a schematic view of another embodiment of a cam according to the present invention. [Figure 11] It is a schematic view of another embodiment of a cam according to the present invention. [Figure 12] It is a first view of the cavity contour of the cam shown in FIG. 1. [Figure 13] It is a second view of the cavity contour of the cam shown in FIG. 1.
Modes for Carrying Out the Invention
[0027] Figure 1 shows, as an example, a pump device 1 in the form of a magnetically coupled pump device of a type known from the prior art. Pump device 1 has a multi-component pump casing 2 of a centrifugal pump, which comprises a hydraulic casing 3 designed as a volute casing, a casing cover 4, a bearing bracket lantern 5, a bearing bracket 6, and a bearing cover 7.
[0028] The hydraulic casing 3 has an inlet opening 8 for taking in the pumped medium and an outlet opening 9 for discharging the pumped medium. The casing cover 4 is located on the side of the hydraulic casing 3 opposite to the inlet opening 8. The bearing bracket lantern 5 is fixed to the side of the casing cover 4 that does not face the hydraulic casing 3. The bearing bracket 6 is attached to the side of the bearing bracket lantern 5 that does not face the casing cover 4. The bearing cover 7 is also fixed to the side of the bearing bracket 6 that does not face the bearing bracket lantern 5.
[0029] The can 10 is fixed to the side of the casing cover 4 that does not face the hydraulic casing 3 and extends at least partially through the internal chamber 11, which is partitioned by the pump casing 2, particularly by the casing cover 4, the bearing bracket lantern 5, and the bearing bracket 6. The can 10 hermetically seals the chamber 12 enclosed by the can from the internal chamber 11.
[0030] The impeller shaft 13, which is rotatable around the rotation axis A, extends from the flow chamber 14, which is partitioned by the hydraulic casing 3 and the casing cover 4, through an opening 15 provided in the casing cover 4 into the chamber 12.
[0031] The impeller 16 is fixed to the shaft end of the impeller shaft 13 located inside the flow chamber 14, and the internal rotor 17, located inside the chamber 12, is positioned at the opposite shaft end. Multiple magnets 18 are attached to the internal rotor 17, and these are positioned on the side of the internal rotor 17 facing the can 10.
[0032] A bearing assembly 19, operably connected to an impeller shaft 13 that can be rotated around axis A, is located between the impeller 16 and the internal rotor 17.
[0033] A drive motor (not shown), preferably an electric motor, drives the drive shaft 20. The drive shaft 20, which can be rotated around a rotation axis A, is positioned substantially coaxially with the impeller shaft 13. The drive shaft 20 extends through a bearing cover 7 and a bearing bracket 6 and is supported by two ball bearings 21, 22 housed in the bearing bracket 6. An external rotor 24 holding a plurality of magnets 23 is positioned at the free end of the drive shaft 20. The magnets 23 are positioned on the side of the external rotor 24 facing the can 10. The external rotor 24 extends at least partially through the can 10 and interacts with the internal rotor 17 by magnetic force such that the rotating external rotor 24 imparts rotational motion to the internal rotor 17, and thus to the impeller shaft 13 and the impeller 16.
[0034] The can 10, shown in enlarged scale in Figures 2 and 3, is provided for attachment to the pump device 1, which is shown in Figure 1 as an example of various magnetically coupled pump devices. The can 10 has a substantially cylindrical body 25 having a longitudinal central axis B substantially coaxial with the rotation axis A according to Figure 1. The body 25 is open on one side and closed on the opposite side by a substantially arched bottom 26. An annular connecting flange 27 is located on the open side, which is integrally designed with the body 25.
[0035] The connecting flange 27 has a plurality of holes 28 extending parallel to the longitudinal central axis B, through which screws (not shown) can be inserted and screwed into the corresponding screw holes of the casing cover 4 as shown in Figure 1.
[0036] The bottom 26 is formed by a cup region 29 that is substantially in the form of a ball-shaped cutout, and an outer rim region 30 that forms a transition region between the main body 25 and the cup region 29.
[0037] As can be seen in relation to Figures 3 and 4, the body 25 has an outer surface 31 having a number of protrusions 32. The outer surface 31 is substantially corrugated in design, each having a number of wave crests 33 and wave troughs 34. The protrusions 32 are helical or spindle-shaped in design, i.e., the protrusions 32 are positioned obliquely to a virtual line L extending parallel to the longitudinal central axis B on the outer surface 31. In the illustrated embodiment, the protrusions 32 and line L form an angle α of 45°. The angle α can vary in the range greater than 0° and less than 90°. The angle α is preferably in the range of 30° to 70°. A channel-shaped cavity 35 extends through the protrusions 32.
[0038] Figure 4 shows a triangular projection 32 having a triangular cavity 35, while Figure 5 shows an elliptical projection 32 having an elliptical cavity 35, both formed on the outer surface 31 of the can 10. Other configurations of the projection 32 are possible. These can have a semicircular or semi-elliptical configuration, or a trapezoidal or some other polygonal configuration, as shown in Figure 6. Figure 7, together with Figure 8, shows another embodiment of the can 10 for use in a magnetically coupled pump device. In the illustrated embodiment, the obliquely extending projection 32 formed on the body 25 is interrupted by a number of projections 32' extending axially, i.e., parallel to the longitudinal central axis B. Channel-shaped cavities 35' connected to the cavities 35 of the obliquely extending projection 32 extend through the axial projections 32'. The configuration of the projections 32' can correspond to the configuration of the projection 32, but the projections 32' may also differ from the configuration of the projection 32.
[0039] Figure 9 shows another modification of the can 10. The diagonally extending protrusions 32 extend at a specific angle α with respect to a virtual line L extending parallel to the longitudinal axis B on the outer surface 31, from one protrusion 32' extending parallel to the longitudinal axis B of the can 10 to the next protrusion 32' extending parallel to the longitudinal axis B of the can 10. The subsequent protrusions 32 extending from the protrusion 32' are positioned at an angle α with respect to line L that substantially corresponds to 360°-α, creating a herringbone configuration.
[0040] Figure 10 schematically shows another configuration of the projection 32 on the outer surface 31 of the can. The projection 32 may have portions 38 and 39 extending axially, i.e., parallel to the axis of rotation A, at least one of their end regions 36, 37, and these portions may also be provided with channel-type cavities as described with reference to the previous figures. The shapes of the projection 32 and the cavities can be selected accordingly.
[0041] Another alternative configuration of the projection 32 is schematically shown in Figure 11. The diagonally extending projection 32, which extends between the axial portions, undergoes a reversal of direction approximately at the center of the body 25, resulting in the formation of a substantially mirrored pattern of the projection 32. In this case, the axial portions 38 and 39 of the projection 32 are substantially coplanar. It is possible to omit the axial portions, and it is clear that the projection 32 can have a pattern oblique to a virtual line L from their start to end, as shown in Figure 3.
[0042] The described embodiments show that the can is designed as a homogeneous component. The can is manufactured by 3D printing.
[0043] Figure 12, in conjunction with Figure 13, shows the cavity contour or profile of the cavity 35 within the can 10, particularly the surface of the cavity shown in Figures 2 and 3. The metallic material appears to have been removed. It is clear that an annular space 40 is formed on the side of the body 25 opposite to the open side, and that the cavity 35 extends from this annular space toward the open side, ultimately opening into the first semi-annular cavity 41 or the second semi-annular cavity 42. The first connecting channel 43 extends from the first semi-annular cavity 41 through the connecting flange 27 shown in Figure 2. The first connecting channel 43 is also shown in Figure 1. The second connecting channel 44 extends from the second semi-annular cavity 42 through the connecting flange 27.
[0044] As can be seen from Figure 13, the first semi-annular cavity 41 has a first inclined region with a chamfered portion 45 and a second inclined region with a chamfered portion 46, which merge at point 47. The second semi-annular cavity 42 has a first inclined region with a chamfered portion 48 and a second inclined region with a chamfered portion 49, which merge at point 50.
[0045] When the open side of the can is facing downwards, the first connection channel 43 and the second connection channel 44 are located at the lowest points of the cavity 41 and cavity 42, respectively.
[0046] This allows loose powder remaining in cavities 35, 35', 40, 41, and 42 during 3D printing to gradually exit these cavities through the area of the bottom 26, through the area of the main body 25, through the area of the connecting flange 27, and finally through the first connecting channel 43 and the second connecting channel 44, respectively, or to be blown out of these cavities.
Claims
1. A magnetically coupled pump device, The pump casing (2) of the pump device forms an internal chamber (11), A can (10) having a longitudinal central axis (B), the can (10) hermetically seals the chamber (12) enclosed by the can to the internal chamber (11) formed by the pump casing (2), An impeller shaft (13) that can be rotated around a rotation axis (A), An impeller (16) positioned at one end of the impeller shaft (13), An internal rotor (17) is positioned at the other end of the impeller shaft (13), An external rotor (24) is positioned on the drive shaft (20) and interacts with the internal rotor (17), Equipped with, A magnetic coupling pump device characterized in that a number of protrusions (32, 32') are provided on the outer side surface (31) of the can (10).
2. The magnetic coupling pump device according to claim 1, characterized in that a number of protrusions (32, 32') are provided on the outer side surface (31) of the can (10), and at least some of them are arranged at an angle.
3. The magnetic coupling pump device according to claim 1 or 2, characterized in that a channel-shaped cavity (35, 35') extends through the protrusion (32, 32').
4. The magnetic coupling pump device according to claim 3, characterized in that the shape of the cavity (35, 35') substantially corresponds to the shape of the protrusion (32, 32'), and the protrusion (32, 32') and the cavity (35, 35') are designed to be triangular, elliptical, circular, semi-elliptical, semi-circular, or trapezoidal, or have some other polygonal configuration.
5. The magnetic coupling pump device according to any one of claims 1 to 4, characterized in that the projection (32) is spiral or spindle-shaped.
6. The magnetic coupling pump device according to any one of claims 1 to 5, characterized in that the protrusion (32) is positioned diagonally with respect to a virtual line (L) extending parallel to the longitudinal central axis (B) on the outer side surface (31), and the protrusion (32) and the line (L) form an angle (α) in the range of greater than 0° and less than 90°.
7. The magnetic coupling pump device according to claim 6, characterized in that the angle (α) is in the range of 30° to 70°.
8. The magnetic coupling pump device according to claim 6 or 7, characterized in that the angle (α) is 45°.
9. The magnetic coupling pump device according to any one of claims 1 to 8, characterized in that the diagonally extending protrusion (32) is interrupted by a number of axially extending protrusions (32').
10. A magnetic coupling pump device according to any one of claims 1 to 9, characterized in that a channel-shaped cavity (35') connected to the cavity (35) of the diagonally extending protrusion (32) extends through the axial protrusion (32').
11. The magnetic coupling pump device according to any one of claims 1 to 10, characterized in that the projection (32) has portions (38, 39) that extend axially to at least one of their end regions (36, 37).
12. A magnetic coupling pump device according to any one of claims 1 to 11, characterized in that the diagonally extending protrusions (32) extending between the axial portions undergo a reversal of direction at approximately the center of the body (25) such that a substantially mirrored pattern of the protrusions (32) exists.
13. A method for manufacturing a can for a magnetic coupling pump, characterized in that a number of protrusions (32, 32') are provided on the outer side surface (31) of the can (10).
14. The method according to claim 13, characterized in that the can (10) having the protrusions (32, 32') and the cavities (35, 35') is manufactured by a method in which the can is manufactured by the selective action of energy radiation on powder layers applied layer by layer.