LU102802B1 - glandless pump - Google Patents

Abstract

The invention relates to a glandless pump (1) with an electric motor (2) driving a pump impeller (4), comprising a stator (10) with a stator core and a rotor (17), which are separated from one another by a can (7) which is formed under an air gap (18) from the stator (10), the rotor, the can (7) and the pump impeller (4) forming a cartridge (5). The can (7) has resilient elevations (13) with which the cartridge (5) is fixed centered on the inside of the stator core. This avoids vibrations in the cartridge (5) and consequently noise emissions caused by vibrations.

Description

WI 810021LU B1u102802

10.5.2021

WILO SE Wilopark 1 44263 Dortmund Wet-running pump The invention relates to a wet-running pump with an electric motor driving a pump impeller, comprising a stator with a stator core and a rotor, which are separated from one another by a can which is spaced apart from the stator to form an air gap, the rotor the can and the pump impeller form a cartridge. Wet rotor pumps are well known. They are characterized by the fact that the rotor rotates inside the cartridge or its can in a liquid, which is usually the liquid conveyed by the pump. The stator essentially consists of a laminated stator core and several stator windings, which are mounted as lap 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 stack which is connected to it in a torque-proof manner and which is usually equipped with permanent magnets. The motor shaft is mounted radially in plain bearings. The rotor is arranged inside the cartridge, which ensures hermetic separation from the stator and the environment. The cartridge forms an assembly that is pushed axially into the stator. On the pump side, this assembly has an end shield, which is integral with the can or firmly connected thereto, which is attached to the motor housing in the manner of a flange or clamped between the motor and pump housing. At the end facing away from the pump, the cartridge, more precisely the can, can be closed by a one-piece bottom, thus forming a can, or be closed by a separate element. The floor or the separate element can form a bearing support and accommodate the rear sliding bearing.

The stator and rotor are manufactured as separate assemblies and then joined together axially.

In order to facilitate axial joining, there is a radial air gap of a few tenths of a millimeter between the cartridge and the stator or its stator core when assembled.

This means that there is no press fit, so that the cartridge protrudes into the stator so that it can move freely radially.

There is also no radial attachment or support at the end facing away from the pump.

Investigations have shown that glandless pumps of this type tend to produce increased noise emissions at certain speeds, which can be attributed to vibrations in the cartridge excited by the rotor, since the cartridge can oscillate relative to the stator.

It is the object of the present invention to minimize vibrations of the cartridge and thereby reduce the noise emissions from glandless pumps.

This problem is solved by a glandless pump with the features of claim 1 .

Advantageous developments are specified in the dependent claims and are explained below.

According to the invention, resilient elevations are provided in the can, with which the cartridge is fixed in a centered manner on the inside of the stator core.

The elevations protrude from the outer surface of the rest of the can and bridge the gap to the stator.

The cartridge is fixed radially in the stator and also centered by the installation of the elevations, which have a spring effect, on the stator core.

This effectively reduces cartridge vibrations relative to the stator and other components of the glandless pump.

The cartridge retains this safe and reliable fixation due to the spring-loaded elevations on the can in all possible operating states of the glandless pump throughout its service life, especially in the event of temperature and/or pressure fluctuations and vibrations.

In addition to the rotor, the 1Lu102802 can and the pump impeller, the cartridge attached to the stator as an assembly also includes other components in a known manner, such as one or two plain bearings that support the motor shaft, which in turn carries the rotor, an axial bearing and/or an end shield , which is arranged in the manner of a flange at the end of the can on the impeller side, possibly even being in one piece with the can.

The surface contour of at least some of the elevations or all elevations can be bumpy or spherical in one embodiment.

In other words, these elevations have such an outer contour that is circular or oval when viewed in section with a plane offset parallel to a plane tangential to the jacket of the can.

In other words, the contact of the stator with the elevations is approximately punctiform.

This has several advantages.

On the one hand, it causes the stresses to be evenly distributed within the individual elevations.

This avoids local stress peaks which, depending on the geometry of the elevations, can lead to damage to the can. Furthermore, this bulge-like or spherical surface contour of the elevations facilitates the axial joining of the cartridge in the stator, since the elevations rise flush from the outer surface of the can and do not protrude stepwise.

The axial joining is also facilitated by a lower expenditure of force, which is due to the comparatively small dimensions of the elevations in the axial direction and in the circumferential direction.

Depending on the material and the type of manufacture of the can, the elevations can be manufactured and designed differently.

If the can is made of plastic, for example, e.g. injection molded, the elevations can be formed during production, e.g. by appropriate shaping in the injection molding tool.

If the can is made of metal, at least some of the elevations or all of the elevations can be made by deforming the material.

This can be done, for example, in that a stamp presses against the inside of the can, for example at a point, and thereby presses the can jacket outwards.

In this way, the elevations are particularly easy to produce.

The use of a can made of metal, in particular made of stainless steel, is a preferred variant, since a plastic can with the same pressure stability requires a greater wall thickness than a can made of metal and also tends to relax in the long run, so that a formerly held firmly in the stator The cartridge can loosen over time as a result of the reduction of internal stresses, and on the other hand it cannot develop a spring effect due to its high brittleness.

The wall thickness of the can in the area of the elevations is preferably essentially the same as the wall thickness of the can beyond the elevations.

In other words, the elevations are not formed by material thickening.

This has the advantage that the elevations have a spring effect and can therefore function as axial damping elements.

This cushions pressure surges from the hydraulics or mechanical shocks on the pump or motor housing.

It makes sense for at least some of the elevations, preferably all elevations, to protrude a maximum of 0.2 mm from the outer casing of the can further than the width of the air gap, so that the axial force required for axial insertion of the cartridge into the stator and the stresses introduced radially into the can remain low , but at the same time the cartridge is radially well fixed.

If the air gap is 0.2mm, for example, the elevations can protrude by up to 0.4mm.

With regard to the number of elevations and their distribution, it has been shown that three elevations, or in other words at least three points at which the cartridge is supported on the stator, are sufficient to effectively reduce vibrations.

However, with three elevations, depending on the angular position of the cartridge relative to the stator during axial joining, there is a risk that they will all be in the gaps or in the gaps.

Slots end up between the stator teeth and thus there is no fixation, especially when the number of slots is a multiple of three, which is regularly the case with a 3-phase motor.

On the other hand, with only three elevations, the deformation of the can between the elevations is comparatively large, with the result that the elevations no longer act as spring elements.

Around

To overcome disadvantages, the three lobes may be circumferentially elongate lobes, for example, versus a spherical shape, or more than three lobes may be used, e.g., 5 or 7. To keep the cartridge centered in the stator, the lobes along distributed equidistantly around the circumference of the can.

With three elevations, these can consequently be offset from one another by 120° in each case, with five elevations by 72° in each case.

The elevations can lie together on one circumference or be axially offset from one another, i.e. lie on different circumferences.

In the stator, the slots are open toward the can, with a stator tooth, which is formed by a peripheral section of the stator core, lying in a known manner between two slots that are adjacent in the circumferential direction.

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.

An odd number of elevations distributed equidistantly in the circumferential direction is preferably selected.

This takes into account the fact that the number of poles 2p of the stator (number of stator teeth) is even, and an even number of elevations, in particular a number of elevations corresponding to the number of poles of the stator, could lead, depending on the angular alignment of the can relative to the stator, that two axially opposite elevations, or in the worst case all elevations in the case of a number of elevations corresponding to the number of poles of the stator, lie between two poles (between two stator teeth) and are therefore not supported on the stator.

An odd number of elevations distributed equidistantly in the circumferential direction prevents this.

Preferably, at least part of the projections is axially offset to another part of the projections.

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 offset axially but merely distributed circumferentially, preferably equidistantly.

For example, there can be three, five or seven elevations on each of two circumferences, i.e. a total of 6, 10 or 14 elevations.

Alternatively, three

Circumferential circles with three, five or seven elevations each exist, i.e. a total of 9, LU102802 or 21 elevations.

If elevations that were axially offset relative to one another were to be arranged along a surface line of the can that is parallel to the axis, there would be a risk that all of these elevations would be directed into the same slot and consequently could not be supported on the stator.

The cartridge would therefore not be arranged exactly centered in the stator.

In order to avoid this, it makes sense if two elevations that are axially offset relative to one another are also offset relative to one another at a circumferential angle.

It is thus ensured that even if an elevation should be opposite a groove, the axially next elevation or at least the next but one elevation is again opposite a stator tooth.

If the elevations are arranged equidistantly along two or more circumferential circles, it makes sense if these circles, i.e. all elevations on these circles, are offset from one another at a circumferential angle.

Even if one of the ridges may be opposite a slot, the circumferential angular offset ensures that the axially adjacent ridge rests against a stator tooth.

Further features, properties, effects and advantages of the invention are explained in more detail below using exemplary embodiments and the attached figures.

The reference symbols contained in the figures retain their meaning from figure to figure.

In the figures, reference symbols always denote the same or equivalent components, areas, directional or locational information.

It should be pointed out that, in the context of the present description, the terms “have”, “comprise” or “contain” in no way exclude the presence of other features.

Furthermore, the use of the indefinite article with an object does not exclude its plural form.

They show: FIG. 1: an exploded view of a glandless pump according to the prior art

Fig. 2: a perspective view of an LU102802 according to the invention

can 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 by means of an elevation shown in the stator Figure 1 shows an exploded view of a glandless pump 1 comprising a pump unit, of which here only the impeller 4 is shown, an electromotive drive unit 2 that drives it, and control electronics 3 for controlling the drive unit 2. The drive unit 2 consists of the stator assembly 6 and a further assembly known as a cartridge 5, which contains the rotor and is inserted axially into the stator assembly 6 is inserted or is.

The control electronics 3 are mounted axially on the stator assembly 6 .

The stator assembly 6 includes the motor housing 9, in the interior of which the stator 10 is accommodated.

The stator 10 consists of a laminated stator package comprising radially inwardly directed stator teeth 11, which are connected to one another via a magnetic yoke ring, and windings 12 mounted on the stator teeth 11. The electromotive drive unit 2 is here a brushless, electronically commutated synchronous motor, for example with three Phases and two windings per phase, so that six stator teeth 11 or 6 windings 12 exist, which are energized by the control electronics 3.

The cartridge 5 comprises a can 7 separating the rotor from the stator 10, at the impeller-side axial end of which an end shield 8 is arranged, e.g. fastened or is integral with it, with the interior of the can 7 being filled with the pumped liquid rotor chamber, in which the rotor is arranged is.

The rotor comprises the motor shaft and a rotor core 17 (see Fig. 4) with permanent magnets which is connected to it in a torque-proof manner, the motor shaft being mounted radially in plain bearings, of which a first plain bearing is arranged approximately at the axial height of the end shield 8 or in front of it on the rotor chamber side, and a second sliding 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 includes the LU102802 motor shaft, at the end of which the impeller is fixed in a rotationally fixed manner, as well as the slide bearings.

In the assembled state of the glandless pump 1, the cartridge 5 with its can 7 extends axially into the motor housing 9 or the stator 10, forming a radial air gap 18 (see FIG. 4) to the stator core or to the stator teeth 11.

In other words, this cartridge 5 is not radially supported, which is why it can oscillate relative to the stator 10 when the glandless pump 1 is in operation.

Figures 2 and 3 show a can 7 according to the invention, which overcomes this disadvantage.

For this purpose, it has elevations 13 that extend radially from its lateral surface or

Outer jacket 15 protrude, for example by 0.3 mm.

The cartridge 5 rests with the elevations 13 formed on the can 7 on the stator 10 , more precisely on the stator teeth 11 .

The elevations 13 thus form mechanical support points that hold the cartridge radially firmly in the stator 10 via the can 7 .

The outer contour of the elevations 13 is bumpy or spherical, so that the contact surface with the stator 10 is essentially punctiform.

The transition from the elevations 13 to the outer jacket 15 is kink-free, so that the forces absorbed by the elevations 13 are diverted to the rest of the can 7 .

The can 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 .

Figure 3 shows this clearly.

The elevations 13 are thus represented as bulges of the can 7.

The elevations 13 are produced by material deformation, in that a stamp, e.g. a round, in particular spherical stamp, presses the can 7 radially outwards from its inside at the locations of the elevations 13 to be produced.

The can 7 carries a total of fifteen elevations 13, with five of the elevations 13 being arranged equidistantly along three parallel circumferential circles 14.

Since there are six slots between the stator teeth 11,

this odd number of elevations 13 per circumference 14 ensures that | u+102802 no two or more elevations 13 of a respective circumferential circle 14 accidentally lie between the stator teeth 11 due to a corresponding angular position of the can 7 relative to the stator 10.

The circumferential circles 14 are axially offset from one another in such a way that a first, central circumferential circle 14 with elevations 13 is located approximately in the axial center of the can 7, and the two other circumferential circles are arranged approximately at the same distance axially in front of and behind the central circumferential circle 14.

Figure 2 also illustrates an angular misalignment between the ridges 13 of adjacent circumscribed circles.

In relation to the central circumferential circle 14, the elevations 13 of the second circumferential circle 14 close to the impeller are offset by an angle a1 in one circumferential direction and the elevations 13 of the third circumferential circle 14 remote from the impeller are offset by an angle «2 in the opposite circumferential direction.

Reference numeral 16 indicates the longitudinal axis of the can.

The angular offset a1, a2 ensures that, even if an elevation 13 of a peripheral circle 14 should be directed into a stator slot, the adjacent elevation 13 of the adjacent peripheral circle 14 is again opposite a stator tooth 11 and is supported on it.

The elevations 13 according to the invention ensure that the can 7 is held in a secure position in the stator 10 .

It is supported with its elevations 13 at certain points on the stator 10 and is therefore no longer able to perform any radial movement relative thereto.

A vibration of the cartridge 5 is thus effectively prevented.

Figure 4 shows a detail of an axial cross-section through the glandless pump 1 in the assembled state of the cartridge 5, the section running through an elevation 13 formed on the can 7, which rests against a stator tooth 11 of the stator core, centered around the cartridge 5 in the stator 10 to fix.

The height of the elevations 13 is selected such that there is a minimum overlap between elevations 13 and the stator tooth 11 in all possible operating conditions such as temperature/pressure fluctuations and vibrations throughout

| Lifetime is guaranteed, which means that the cartridge is no longer the source of LU102802 noise emissions. The height of the elevations 13 is chosen so that a minimum overlap between elevations 13 and the stator tooth 11 is guaranteed in all possible operating conditions such as temperature/pressure fluctuations and vibrations throughout the service life, as a result of which the cartridge 5 is no longer the source of noise emissions. It should be understood that the foregoing description is given by way of example for purposes of illustration and does not limit the scope of the invention in any way. Features of the invention indicated as "may", "exemplary", "preferred", "optional", "ideal", "advantageous", "if necessary", "suitable" or the like are to be considered purely optional and limiting also does not enter the scope of protection, which is defined solely by the claims. Insofar as elements, components, process steps, values or information are mentioned in the above description which have known, obvious or foreseeable equivalents, these equivalents are also included in the invention. The invention also includes any changes, alterations or modifications of exemplary embodiments which have the exchange, addition, alteration or omission of elements, components, method steps, values or information as their subject matter, as long as the basic idea according to the invention is retained, regardless of whether the change, alteration, or modifications improves or degrades an embodiment. Although the above description of the invention mentions a large number of physical, non-physical or procedural features in relation to one or more specific exemplary embodiments, these features can also be used in isolation from the specific exemplary embodiment, at least insofar as they do not necessarily require the presence of further features. Conversely, these features mentioned in relation to one or more specific exemplary embodiment(s) can be arbitrarily combined with one another and with further disclosed or non-disclosed features of exemplary embodiments shown or not shown

ZELL can be combined, at least insofar as the features are not mutually exclusive LU102802 or lead to technical incompatibilities. hey

Claims (1)

WI 810021LU C LU102802 5/10/2021 Claims 1. Wet-running pump (1) with an electric motor (2) driving a pump impeller (4) comprising a stator (10) with a stator core and a rotor (17), which are separated from one another by a can (7) which forms an air gap (18) is spaced from the stator (10), the rotor, the can (7) and the pump impeller (4) forming a cartridge (5), characterized in that the can (7) has resilient elevations (13) with which the cartridge (5) is centered on the inside of the stator core. 2. glandless pump (1) according to claim 1, characterized in that the surface contour of at least part of the elevations (13) is bumpy or spherical. 3. glandless pump (1) according to claim 1 or 2, characterized in that at least some of the elevations (13) are produced by material deformation. | 4. Wet-running pump (1) according to one of the preceding claims, characterized in that the can (7) consists of metal, in particular stainless steel. 5. glandless pump (1) according to any one of the preceding claims, characterized in that the wall thickness of the can (7) in the region of the elevations (13) is substantially equal to the wall thickness of the can (7) beyond the elevations (13). 6. Wet-running pump (1) according to one of the preceding claims, characterized in that at least some of the elevations (13) protrude a maximum of 0.2 mm from the outer casing (15) of the can (7) further than the air gap (18) is wide. 7. Wet-running pump (1) according to one of the preceding claims, characterized in that the elevations (13) are distributed equidistantly along the circumference of the can. 8. glandless pump (1) according to any one of the preceding claims, characterized in that at least part of the elevations (13) is axially offset to another part of the elevations (13). 9. glandless pump (1) according to any one of the preceding claims, characterized in that two axially offset elevations (13) are also offset in a circumferential angle to each other. 10. glandless pump (1) according to any one of the preceding claims, characterized in that the elevations (13) are arranged equidistantly along at least two circumferential circles (14), which are offset from each other at a circumferential angle.