GUM PUMP

Description

[0001] The invention relates to a wet rotor pump with an electric motor driving a pump impeller comprising a stator with a stator package and a rotor, which are separated from each other by a can which is spaced from the stator to form an air gap, wherein the rotor, the can and the pump impeller form a cartridge.

[0002] Glandless pumps are well known. They are characterized by the rotor rotating within the cartridge or its can in a fluid, which is usually the fluid pumped by the pump. The stator essentially consists of a laminated stator core and several stator windings, which are mounted as loop windings in slots of the stator core or as concentrated windings on the stator teeth of the stator core. The rotor comprises the motor shaft and a rotor core connected to it for rotation, which is usually equipped with permanent magnets. The motor shaft is mounted radially in plain bearings. The rotor is located within the cartridge, which ensures hermetic separation from the stator and the environment.

[0003] The cartridge forms an assembly that is inserted axially into the stator. On the pump side, this assembly, either integral with the can or firmly connected to it, has a bearing plate that is attached to the motor housing like a flange or clamped between the motor and pump housings. At the end facing away from the pump, the cartridge, or more precisely the can, can be closed by a one-piece base, thus forming a containment shell, or can be closed by a separate element. The base or the separate element can form a bearing carrier and accommodate the rear plain bearing. The stator and rotor are manufactured as separate assemblies and then joined axially. To facilitate axial joining, a radial air gap of a few tenths of a millimeter exists between the cartridge and the stator or its stator package in the assembled state. This meansThere is no interference fit, so the cartridge protrudes into the stator, virtually free to move radially. There is also no radial fastening or support at the end facing away from the pump.

[0004] Studies have shown that wet rotor pumps of this type tend to produce increased noise emissions at certain speeds, which are due to vibrations of the cartridge excited by the rotor, as the cartridge can oscillate relative to the stator.

[0005] US 8 696 333 B2 discloses a wet rotor pump according to the preamble of claim 1.

[0006] The object of the present invention is to minimize vibrations of the cartridge and thereby reduce the noise emission of wet-running pumps.

[0007] This object is achieved by a wet-running pump having the features of claim 1. Advantageous further developments are specified in the subclaims and are explained below.

[0008] According to the invention, resilient protrusions are provided on the can, which center the cartridge on the inside of the stator core. These protrusions protrude from the outer surface of the remaining can and bridge the gap to the stator. By applying the resilient protrusions to the stator core, the cartridge is radially fixed in the stator and also centered. This effectively reduces vibrations of the cartridge relative to the stator and other components of the wet-running pump.

[0009] This secure and reliable fixation of the cartridge is ensured by the spring-loaded protrusions on the can in all possible operating conditions of the wet-running pump throughout its entire service life, particularly in the event of temperature and / or pressure fluctuations as well as vibrations.

[0010] In addition to the rotor, the can and the pump impeller, the cartridge, which is attached to the stator as an assembly, also includes other components such as one or two plain bearings that support the motor shaft, which in turn supports the rotor, an axial bearing and / or a bearing shield that is arranged in the manner of a flange at the impeller-side end of the can, and may even be integral with the can.

[0011] The surface contour of at least some or all of the elevations can be bulge-like or spherical in one design variant. In other words, these elevations have an outer contour that is circular or oval when viewed in section with a plane parallel to a tangential plane on the casing of the can. In other words, the contact of the elevations with the stator is almost point-like. This has several advantages. Firstly, it ensures that the stresses are distributed evenly within the individual elevations. This avoids local stress peaks which, depending on the geometry of the elevations, could lead to damage to the can. Furthermore, this bulge-like or spherical surface contour of the elevations facilitates the axial joining of the cartridge into the stator, since the elevations rise flush from the casing surface of the can and do not protrude in a step-like manner.Axial joining is also facilitated by the lower effort required due to the comparatively small dimensions of the elevations in the axial and circumferential directions.

[0012] Depending on the material and manufacturing method of the split tube, the raised portions can be manufactured and designed differently. For example, if the split tube is made of plastic, e.g., injection-molded, the raised portions can be formed during production, e.g., by appropriate shaping in the injection molding tool.

[0013] If the can is made of metal, at least some or all of the raised portions can be created by material deformation. This can be achieved, for example, by applying a stamp to the inside of the can, for example, in a point-like manner, thereby pushing the can casing outward. This makes the raised portions particularly easy to produce.

[0014] The use of a metal can, particularly stainless steel, is a preferred design variant, since a plastic can requires a greater wall thickness than a metal can for the same pressure stability and, furthermore, it tends to relax over time, so that a cartridge that was previously held firmly in the stator can loosen over time as a result of the reduction of internal stresses, and, secondly, it cannot develop a spring effect due to its high brittleness.

[0015] Preferably, the wall thickness of the can in the area of ​​the raised portions is essentially the same as the wall thickness of the can beyond the raised portions. In other words, the raised portions are not formed by thickened material. This has the advantage that the raised portions have a spring effect and can thus act as axial damping elements. Pressure surges from the hydraulic system or mechanical shocks to the pump or motor housing are thus cushioned.

[0016] It is advisable for at least some of the raised portions (preferably all raised portions) to protrude from the outer surface of the can by a maximum of 0.2 mm further than the air gap width. This minimizes the axial force required for axial insertion of the cartridge into the stator and the radial stresses introduced into the can, while simultaneously ensuring the cartridge is well secured radially. For example, if the air gap is 0.2 mm, the raised portions can protrude up to 0.4 mm.

[0017] Regarding the number of protrusions and their distribution, it can be seen that just three protrusions, or in other words at least three points where the cartridge rests on the stator, are sufficient to effectively reduce vibrations. However, with three protrusions, depending on the angular position of the cartridge relative to the stator during axial joining, there is a risk that they will all end up in the gaps or grooves between the stator teeth and thus no fixation is achieved, especially if the number of grooves is a multiple of three, which is regularly the case with a 3-phase motor. Secondly, with only three protrusions, the deformation of the can between the protrusions is comparatively large, which means that the protrusions no longer function as spring elements.To overcome these disadvantages, the three elevations can be designed as elongated elevations in the circumferential direction, for example, as opposed to a spherical shape, or more than three elevations can be used, e.g. 5 or 7.

[0018] To keep the cartridge centered in the stator, the protrusions can be distributed equidistantly along the circumference of the can. With three protrusions, these can be offset by 120° from each other, and with five protrusions, by 72° from each other. The protrusions can be located together on one circumferential circle or axially offset from each other, i.e., on different circumferential circles.

[0019] In the stator, the slots are open toward the can, with a stator tooth formed by a circumferential section of the stator core being located between two circumferentially adjacent slots in a known manner. The number of poles (2p) of the motor determines how many stator teeth and slots the stator has. The slots and stator teeth extend parallel to the axis. Preferably, an odd number of elevations distributed equidistantly in the circumferential direction is selected.This takes into account the fact that the stator's pole number 2p (number of stator teeth) is even, and an even number of protrusions, especially a number corresponding to the stator's pole number, could, depending on the angular orientation of the can relative to the stator, result in two axially opposing protrusions, or, in the case of a number corresponding to the stator's pole number, in the worst case, all protrusions, being located between two poles (between two stator teeth) and thus not being supported on the stator. An odd number of protrusions distributed equidistantly in the circumferential direction prevents this.

[0020] Preferably, at least some of the elevations are axially offset from another part of the elevations. For example, a first part of the elevations can be arranged along a first circumferential circle and a second part of the elevations can be arranged along a second circumferential circle offset from the first. The elevations lying within the same circumferential circle are then not axially offset, but merely distributed circumferentially, preferably equidistantly. For example, there can be three, five or seven elevations on each of two circumferential circles, i.e. a total of 6, 10 or 14 elevations. Alternatively, there can also be three circumferential circles, each with three, five or seven elevations, i.e. a total of 9, 15 or 21 elevations.

[0021] If axially offset elevations were arranged along an axially parallel surface line of the can, there would be a risk that all of these elevations would be directed into the same groove and thus unable to support themselves on the stator. The cartridge would therefore not be precisely centered in the stator. To avoid this, it is advisable for two axially offset elevations to also be offset at a circumferential angle. This ensures that even if one elevation is opposite a groove, the axially next elevation, or at least the one after that, is opposite a stator tooth.

[0022] If the elevations are arranged equidistantly along two or more circumferential circles, it is advisable for these circles, i.e., all elevations on these circles, to be offset from each other at a circumferential angle. Even if one of the elevations is opposite a slot, the circumferential angle offset ensures that the axially adjacent elevation rests against a stator tooth.

[0023] Further features, properties, effects, and advantages of the invention are explained in more detail below with reference to exemplary embodiments and the accompanying figures. The reference symbols contained in the figures retain their meaning from figure to figure. In the figures, reference symbols always designate the same or equivalent components, areas, directions, or locations.

[0024] It should be noted that, in the context of this description, the terms "have," "comprise," or "include" in no way exclude the presence of other features. Furthermore, the use of the indefinite article for an object does not exclude its plural form. The following show: Fig. 1: an exploded view of a wet-running pump according to the prior art Fig. 2: a perspective view of a can according to the invention Fig. 3: a section of an axial cross section through the can according to the invention Fig. 4: a section of an axial cross section through the cartridge centered and fixed in the stator by means of a shown elevation

[0025] Figure 1shows an exploded view of a wet-running pump 1 comprising a pump unit, of which only the impeller 4 is shown here, an electromotive drive unit 2 driving the impeller, and control electronics 3 for controlling the drive unit 2. The drive unit 2 consists of the stator assembly 6 and a further assembly referred to as a cartridge 5, which contains the rotor and is or is inserted axially into the stator assembly 6. The control electronics 3 is mounted axially on the stator assembly 6.

[0026] The stator assembly 6 comprises the motor housing 9, in the interior of which the stator 10 is housed. The stator 10 consists of a laminated stator core comprising radially inwardly directed stator teeth 11, which are connected to one another via a magnetic return ring, and windings 12 mounted on the stator teeth 11. The electromotive drive unit 2 here is a brushless, electronically commutated synchronous motor, for example with three phases and two windings per phase, so that there are six stator teeth 11, or six windings 12, which are powered by the control electronics 3.

[0027] The cartridge 5 comprises a can 7 separating the rotor from the stator 10, at the impeller-side axial end of which a bearing plate 8 is arranged, for example, attached or integral with it, wherein inside the can 7 there is a rotor chamber filled with the conveying liquid, in which the rotor is arranged. The rotor comprises the motor shaft and a rotor package 17 connected thereto in a rotationally fixed manner (see Fig. 4) with permanent magnets, wherein the motor shaft is radially mounted in plain bearings, of which a first plain bearing is arranged approximately at the axial height of the bearing plate 8 or in front of it on the rotor chamber side, and a second plain bearing is arranged in a bearing carrier which closes the can 7 on the axial end facing away from the impeller 4. The cartridge 5 thus also comprises the motor shaft, to the end of which the impeller is non-rotatably attached, as well as the plain bearings. In the assembled state of the wet rotor pump 1, the cartridge 5 extends with its can 7 forming a radial air gap 18 (see Fig. 4 ) to the stator package or to the stator teeth 11 axially into the motor housing 9 or the stator 10. In other words, this cartridge 5 is not radially supported, which is why it can oscillate relative to the stator 10 during operation of the wet rotor pump 1.

[0028] Figures 2 and 3show a can 7 according to the invention that overcomes this disadvantage. It has elevations 13 that protrude radially from its outer surface or outer casing 15, for example, by 0.3 mm. The cartridge 5 rests against the stator 10, more precisely, against the stator teeth 11, with the elevations 13 formed on the can 7. The elevations 13 thus form mechanical support points that hold the cartridge radially firmly in the stator 10 via the can 7.

[0029] The outer contour of the elevations 13 is bump-like or spherical, so that the contact surface to the stator 10 is essentially point-shaped.

[0030] The transition of the elevations 13 into the outer casing 15 is kink-free, so that the forces absorbed by the elevations 13 are diverted into the remaining can 7.

[0031] The gap tube 7 is made of metal, in particular stainless steel, and has a uniform wall thickness, which is also essentially constant in the area of ​​the elevations 13. This allows Figure 3 clearly visible. The elevations 13 thus represent bulges in the can 7. The elevations 13 are produced by material deformation, in which a punch, e.g., a round, particularly spherical punch, presses the can 7 radially outward from its inner side at the locations where the elevations 13 are to be produced.

[0032] In total, the can 7 carries fifteen elevations 13, with five of the elevations 13 being arranged equidistantly along three parallel circumferential circles 14. Since there are six grooves between the stator teeth 11, this odd number of elevations 13 per circumferential circle 14 ensures that two or more elevations 13 of a respective circumferential circle 14 do not accidentally lie between the stator teeth 11 due to a corresponding angular position of the can 7 relative to the stator 10.

[0033] The circumferential circles 14 are axially offset from one another in such a way that a first, central circumferential circle 14 with elevations 13 lies approximately in the axial center of the can 7, and the two other circumferential circles are arranged at approximately the same distance axially in front of and behind the central circumferential circle 14. Figure 2also illustrates an angular offset between the elevations 13 of adjacent circumferential circles. Thus, relative to the central circumferential circle 14, the elevations 13 of the second circumferential circle 14 near the impeller are offset by an angle α1 in one circumferential direction, and the elevations 13 of the third circumferential circle 14 far from the impeller are offset by an angle α2 in the opposite circumferential direction. Reference numeral 16 indicates the longitudinal axis of the can. The angular offset α1, α2 ensures that, even if an elevation 13 of a circumferential circle 14 is directed into a stator slot, the adjacent elevation 13 of the adjacent circumferential circle 14 is again opposite a stator tooth 11 and is supported on it.

[0034] The elevations 13 according to the invention ensure a secure position of the can 7 in the stator 10. It rests on the stator 10 with its elevations 13 and is thus no longer capable of radial movement relative to it. Vibration of the cartridge 5 is thus effectively prevented.

[0035] The Figure 4shows a section of an axial cross-section through the wet-running pump 1 with the cartridge 5 installed, with the section passing through a protrusion 13 formed on the can 7, which rests against a stator tooth 11 of the stator core to fix the cartridge 5 centrally in the stator 10. The height of the protrusions 13 is selected such that a minimum overlap between the protrusions 13 and the stator tooth 11 is ensured under all possible operating conditions, such as temperature / pressure fluctuations and vibrations, throughout the entire service life, whereby the cartridge is no longer the source of noise emissions.

[0036] The height of the elevations 13 is selected such that a minimum overlap between elevations 13 and the stator tooth 11 is ensured under all possible operating conditions such as temperature / pressure fluctuations and vibrations throughout the entire service life, whereby the cartridge 5 is no longer the source of noise emissions.

[0037] It should be noted that the foregoing description is provided merely by way of example for illustrative purposes and in no way limits the scope of the invention. Features of the invention stated as "may," "exemplary," "preferred," "optional," "ideal," "advantageous," "optionally," "suitable," or the like are to be considered purely optional and do not limit the scope of protection, which is determined exclusively by the claims. To the extent that the foregoing description recites elements, components, method steps, values, or information that have known, obvious, or foreseeable equivalents, these equivalents are encompassed by the invention.Likewise, the invention includes any changes, variations or modifications of embodiments that involve the replacement, addition, change or omission of elements, components, method steps, values ​​or information, as long as the basic idea of ​​the invention is retained, regardless of whether the change, variation or modifications lead to an improvement or deterioration of an embodiment.

[0038] Although the above description of the invention mentions a multitude of physical, non-physical, or method-related features in relation to one or more specific embodiments, these features can also be used in isolation from the specific embodiment, at least as long as they do not require the mandatory presence of further features. Conversely, these features mentioned in relation to one or more specific embodiments can be combined with each other as desired, as well as with other disclosed or undisclosed features of shown or not shown embodiments, at least as long as the features do not exclude each other or lead to technical incompatibilities.

Claims

1. Wet rotor pump (1) with an electric motor (2) that drives a pump impeller (4), comprising a stator (10) with a stator assembly and a rotor (17) that are separated from each other by a can (7), which is at a distance from the stator (10) to form an air gap (18), in which the rotor, the can (7) and the pump impeller (4) form a cartridge (5), characterised in that the can (7) has resilient projections (13) that centre and secure the cartridge (5) inside the stator assembly.

2. Wet rotor pump (1) according to claim 1, characterised in that the surface contour of at least a part of the projections (13) is bulging or spherical.

3. Wet rotor pump (1) according to claim 1 or 2, characterised in that at least a part of the projections (13) is produced by the deformation of material.

4. Wet rotor pump (1) according to one of the preceding claims, characterised in that the can (7) is made of metal, notably stainless steel.

5. Wet rotor pump (1) according to one of the preceding claims, characterised in that the wall thickness of the can (7) in the area of the projections (13) is essentially equal to the wall thickness of the can (7) beyond the projections (13).

6. Wet rotor pump (1) according to one of the preceding claims, characterised in that at least a part of the projections (13) projecting from the outer casing (15) of the can (7) by a maximum of 0.2mm more than the width of the air gap (18).

7. Wet rotor pump (1) according to one of the preceding claims, characterised in that the projections (13) are distributed equidistantly along the circumference of the can.

8. Wet rotor pump (1) according to one of the preceding claims, characterised in that at least a part of the projections (13) is axially offset to the other part of the projections (13).

9. Wet rotor pump (1) according to one of the preceding claims, characterised in that two axially offset projections (13) are offset to each other at a circumferential angle.

10. Wet rotor pump (1) according to one of the preceding claims, characterised in that the projections (13) are arranged equidistantly along at least two circumferential circles (14) that are offset to each other at a circumferential angle.