DE102017206759A1 - ROTOR FOR AN ELECTRIC MOTOR WITH A SPECIALLY SHAPED RECYCLING ELEMENT AND METHOD OF MANUFACTURING THEREOF - Google Patents

Abstract

A rotor for an electric motor comprises a motor gap (40), comprising: a plurality of permanent magnets (11, 12, 13, 14) attached to each other, each permanent magnet having a side (15c) facing the motor gap; wherein the rotor is configured as an external rotor rotor, and an annular magnetic return element (202), wherein the magnetic return element (202) has a first region (202a), a second region (202b) and a third region (202c), wherein the first region (202a) has a first inner diameter, wherein in the second region (202b) the plurality of permanent magnets (14) is arranged, and wherein the second region has a second inner diameter, wherein the third region has a third inner diameter, and wherein the second inner diameter is larger is the first inner diameter and the third inner diameter, and wherein the third inner diameter is larger than the first inner diameter, and wherein the third inner diameter is larger than an outer diameter of a stator (200) for the electric motor

Description

The present invention relates to electric motors, and more particularly to rotors for such electric motors. The electric motors can be used universally. However, special attention is drawn to the use in a heat pump.

The EP 2 549 113 A2 discloses a magnetic rotor and a rotary pump with a magnetic rotor. The rotor is for driving a fluid in a pump housing within a stator of the rotary pump magnetically non-contact drivable and storable. In addition, the rotor is encapsulated by means of an outer encapsulation comprising a fluorinated hydrocarbon. Within the encapsulation, the rotor comprises a permanent magnet encased in a metal jacket. The rotary pump includes a pump housing having an inlet for supplying a fluid and an outlet for discharging the fluid. The fluid is, for example, a chemically aggressive acid with a proportion of a gas, e.g. As sulfuric acid with ozone. To convey the fluid, a magnetic rotor is magnetically non-contact in the pump housing. The rotor is further provided with a magnetic drive having electric coils. The stator is formed with laminated iron, which is in magnetic operative connection with the permanent magnet of the rotor. The drive is designed as a bearingless motor in which the stator is designed as a bearing stator and drive stator at the same time. The rotor is designed as a pancake, wherein the axial height of the rotor is less than or equal to half the diameter of the rotor.

The dissertation ETH No. 12870, "The bearingless disk motor", N. Barletta, 1998, discloses magnetically levitated disk motors. Magnetic bearings work completely free from contact, wear, maintenance and lubricant. For the active stabilization of a degree of freedom, two controllable electromagnets including electronic control are required. The bearingless disc motor is used within a bearingless blood pump as a bearingless disc motor with active axial bearing, as a miniature disc motor, or as a bearingless bioreactor. By a combination of passive reluctance magnetic bearings and bearingless motor, it is possible to completely support a disc rotor with only two actively stabilized radial degrees of freedom. Requirements for a large air gap, which is necessary in hermetic systems, are met by the choice of a bearingless permanent magnetically excited synchronous motor. A bearingless disc motor suitable for driving an axial pump for cardiac assist is designed for speeds of 30,000 revolutions per minute, resulting in a smaller size.

Commercial electric disc motors are also known by the name "Pan Cake Motor" ("pancake motor"). The engine concept illustrated in the two preceding references is characterized in that the stator extends around the rotor. Such engines are also referred to as internal rotor.

In the case of the internal rotor concept, there is the problem that the stator always has to be larger than the rotor, that is, the size and design of the rotor is always limited by the stator housing or that the rotor dominates the formation of the stator. Thus, the field of application of such a disc motor, which is designed as an internal rotor, limited.

In addition, disk motors generally have the problem that the rotor, regardless of whether it is designed as an internal rotor or external rotor, pressure differences or pressures in certain directions is exposed. These pressures cause a bearing to be loaded in the direction of pressure acting on the rotor, thus increasing wear, or, if rotor deflection is allowed, the rotor is deflected in that direction and thus leeway for this deflection must be provided. In particular, when the pump is used to pump a medium from a pressure area at a first pressure to a pressure area at a second pressure, or to generate such a pressure difference at all, complex design measures must be taken to either a required To achieve wear resistance, or to provide a margin for an occurring deflection.

A disadvantage of electric motors and in particular electric motors that are operated in warm environments or to provide high performance, is the ubiquitous heat development. High temperatures in the electric motor on the one hand affect the typically arranged on the rotor permanent magnet. Thus, if the stator of an engine is too warm, the heat is transmitted via the motor gap to the rotor and the permanent magnets present there with all the associated problems. On the other hand, the heating of the stator itself is critical. The stator is typically provided with coils. Heating the coils can lead to high thermal stress. This high thermal stress in the coils can lead to fatigue of the coil wire insulation in the longer term. In addition, problems may occur with respect to a delamination of the sheet metal body, ie the stator body, which consists of a sheet metal body. In addition, due to elevated temperatures or high thermal fatigue deformations or Faults in the stator cause the engine is not as running as it should or could run.

Especially with high-speed motors with speeds over 30,000 revolutions per minute, even if there is a lower pressure in the engine gap compared to the ambient pressure, the friction with the gas located there is still so great that the permanent magnets of the rotor, which are arranged directly in the motor gap , are exposed to this high friction energy in the motor gap and thus the heat generated there. Permanent magnets have the characteristic that when they get too hot they lose their functionality / magnetization. This damage is in some cases even irreversible and can lead to complete failure of the entire electric motor. But even in the operation of the electric motor, it is of great importance for all parameters that the permanent magnets are kept in an optimal temperature range, which is not ensured due to the high heat generation due to the friction in the motor gap.

The EP 2 975 731 A2 discloses a pancake for an electric machine having a circular or annular disk-like rotor body and permanent magnets arranged circumferentially adjacent to each other on the rotor body. In particular, the rotor body comprises a first material for dissipating heat in the radial direction and further comprises a second electrically non-conductive material in the region of the permanent magnets. Further, in order to hold the permanent magnets reliably on the support member, the support member is provided with a peripheral edge on which the permanent magnets can be supported to the outside. This edge is just like the area in which the permanent magnets are used, formed of a thermally highly conductive material, such as aluminum.

The problem with this concept, however, is that the rotor is effectively used to cool the motor gap. The heat of the motor gap is transmitted by the edge of thermally well conductive material directly to the permanent magnets. Although the permanent magnets are in turn arranged on a thermally highly conductive material, such as aluminum. However, a large amount of heat energy dissipated from the motor gap passes through the permanent magnets. The permanent magnets are therefore constantly exposed to thermal stress. The higher the engine speed, the higher the thermal stress becomes. H. the higher the friction in the motor gap becomes.

Another problem is the design of the magnetic return element. One way to provide the magnetic return element on which permanent magnets are arranged is to use a circular return element or an annular return element depending on the external rotor or inner rotor implementation. However, the problem is the stability of the entire arrangement. In particular, for an external rotor rotor, the distance of the return element from the axis of rotation is so large that considerable centrifugal forces act on the return element, especially when very high speeds are desired, such as over 20,000 U / min. In such a case, the magnetic return element is very susceptible to destruction, which would immediately lead to destruction of the entire motor. In addition, the mass of the magnetic return element, which is due to the fact that it is located on the outside of the permanent magnet, and thus far away from the axis of rotation, to the fact that when the return element is not perfectly symmetrical, imbalances can immediately arise , On the other hand, a certain mass of return element is necessary to fulfill the actual function, namely to provide the inference for the magnetic field lines.

The object of the present invention is to provide an improved concept for a rotor of an electric motor.

This object is achieved by a rotor for an electric motor according to claim 1, a method for producing the rotor according to claim 26, an electric motor according to claim 27 or a heat pump according to claim 31.

The present invention according to one aspect is based on the finding that optimum protection of the permanent magnets with respect to the resulting heat in the motor gap is achieved in that the permanent magnets are not provided with a good heat conducting material to the motor gap out, but with a material with poor thermal conductivity, ie with a heat shielding functionality. This ensures that the heat remains in the motor gap and is hardly introduced from there into the rotor with the sensitive permanent magnet, but is either discharged directly from the motor gap or is led from the motor gap via the stator and from there to a heat sink. Thus, the heat-sensitive component of the entire electric motor, namely the plurality of permanent magnets, which are arranged on the rotor, secured against the heat in the motor gap. Further, if the stator is insufficiently cooled, there may be the case that even the stator gives off heat to the motor gap. Due to the heat shield on the permanent magnet towards the motor gap, however also ensures that this heat is transferred as little as possible to the rotor.

The rotor for an electric motor comprises a plurality of permanent magnets fixed to each other, wherein each permanent magnet has a side facing the motor gap. Further, as a heat shield, a first coating is disposed on the sides of the permanent magnets facing the motor gap, wherein the first coating has a first, low thermal conductivity. In addition, a second coating is provided which is in contact with a respective other side of the plurality of permanent magnets, wherein the second coating has a second thermal conductivity that is greater than the first thermal conductivity. This second coating ensures that even the low heat that is introduced into the permanent magnets via the first coating with the low thermal conductivity is immediately dissipated by them. In addition, since the second coating is arranged on the permanent magnet, on a side which is not in contact with the first coating, it can even be ensured that heat which nevertheless dissipates via the first coating does not pass through the permanent magnet or so is dissipated as little as possible by the permanent magnet, but by the second good thermal conductivity coating.

Depending on the embodiment, the two coatings are formed of different materials or of the same base material, wherein the different thermal conductivities of the different layers are achieved by a number of packing in the second good thermal conductivity coating is greater than the number of packing in the first coating. For example, epoxy resin itself is relatively poor in heat conductivity, so it is well suited for heat shielding on the permanent magnet. However, a filling with metallic packing significantly increases the thermal conductivity of the epoxy resin. Preferably, therefore, the first coating used is epoxy resin without filler or with a very small number of random packings, while the second coating used is an epoxy resin coating with a high number of random packings, which in any case is greater than the number of random packings in the first coating. It should be noted, however, that different materials with different thermal conductivities can be used.

Preferably, furthermore, the plurality of permanent magnets are mounted on a magnetic return element which, in regions adjacent to the permanent magnets, ie regions which are laterally with respect to the motor gap, defines a space which is filled by the second coating.

It is further preferred that the first coating is arranged continuously above the second coating, so that the motor gap and also the adjacent lateral regions with respect to the motor gap has a continuous surface on the rotor. Thus, the friction is kept as small as possible, because no rough surfaces or surfaces with depressions exist, but a smooth surface of the first coating, which is in the region of the permanent magnet directly on the permanent magnet, and in the area next to the permanent magnet on the second good heat conducting coating is arranged, the completion of the rotor defined towards the motor gap. This ensures, on the one hand, that due to the heat shielding, as little heat as possible reaches the permanent magnets, while the second good heat-conducting coating, which is under the heat shield in the area adjacent to the permanent magnets, ensures that dissipated heat nevertheless dissipates as well as possible is, without permanently exposing the permanent magnets too much thermal stress.

According to another aspect of the present invention, the rotor is formed as an external rotor rotor, in which the permanent magnets define a ring with an inner diameter, in which the stator of the motor, on which the coils are located, is arranged. The permanent magnets are further applied to an annular magnetic return element, said magnetic return element a first lower portion, a second, z. B. middle area and a third, z. B. upper area. The first and lower regions include a first lower inner diameter, the second central region carries the plurality of permanent magnets, and the second central region further has a second or inner inner diameter. In addition, an upper inner diameter or third inner diameter is also present in the upper region. The second inner diameter is further larger than the first inner diameter and the third inner diameter is larger than the first inner diameter. In addition, the third inner diameter is larger than an outer diameter of a stator for the electric motor.

Thus, a cross-sectionally U-shaped magnetic return element is obtained, which on the one hand provides a good magnetic inference, which is essential for the functionality of the electric motor. On the other hand, it is ensured by the formation of the magnetic return element that as much material as possible in the smallest possible distance is arranged to the central axis of rotation. The closer a material of the magnetic return element is arranged on the axis of rotation, the closer the center of gravity of the magnetic return element is arranged in total on the axis of rotation. This is particularly important for an external rotor rotor, because the centrifugal forces acting on all elements of the external rotor rotor, the larger, the farther the corresponding material portion of the rotary shaft is removed. Thus, a much more stable construction can be obtained, compared to a return element which is simply arranged as a ring behind the permanent magnets.

However, in order to enable assembly by simple means, according to this aspect of the present invention, an inner diameter, namely, the third inner diameter will be larger than an outer diameter of a stator of the electric motor, so that the stator and the rotor can be assembled with each other without the magnetic return element perform multi-part, which in turn could bring stability problems with it, especially at very high speeds over z. B. 30,000 to 50,000 revolutions per minute. However, such speeds are required for particular magnetically mounted disc motors for heat pumps to achieve a heat pump with high space efficiency, ie with a good efficiency based on the smallest possible space consumption of the compressor of the heat pump. But also for applications other than heat pumps, a space efficiency, ie a small space requirement with high efficiency is useful.

Characterized in that the first inner diameter is smaller than the third inner diameter, it is ensured that on the other side of the return element, ie on the side through which the stator is not mounted, as much material of the magnetic return element is arranged as close to the axis of rotation in such a way that field lines see a conclusion, but this inference brings about no or only greatly reduced mechanical problems with regard to the stability of the magnetic return element and the entire arrangement due to the intelligent placement of the return material. Further, it is preferable to attach to the portion of the magnetic return element having the smallest inner diameter a portion of the rotor to be rotated, such as a radial wheel using the example of a turbo-engine or a compressor motor for a heat pump. The provision of a return element with a very large surface and thus a very small inner diameter allows that a good attachment between the return element and the element to be rotated is possible, so that a high surface is provided, which can be used constructively to the return element and in order to position the permanent magnets which are decisive for the motor on the element to be rotated.

In preferred embodiments of the magnetic return element aspect, the first and second coatings are further applied to shield the heat from the permanent magnet and dissipate the heat passing through the shield. It should be noted, however, that the aspect of the heat shield can also be used for other motor concepts with other magnetic return elements. Similarly, the aspect of the magnetic return element, which is equipped with different inner diameters and thus in cross-section U-shaped, can also be used directly, ie without heat shield or even, as in the prior art, with a thermally conductive coating, ie a thermally conductive edge. These applications for such implementations arise when the thermal problems are not so great or when the environment in which the engine is running in total, is very cold and thus automatically prevails a situation in which thermal problems are not present.

In particularly preferred embodiments, however, both aspects are combined, ie the U-shaped magnetic return element together with the heat-shielding coating on the permanent magnet and the heat conductive coating next to the permanent magnet. The second thermally conductive coating next to the permanent magnets can namely be used there in particular in the region of the U-shaped magnetic return element, which is arranged next to the permanent magnet.

Furthermore, it is preferable to further structure the cross section of the magnetic return element, that is to say to provide it with transition regions which are arranged between the second or central region in which the magnets are arranged and the upper or lower region. For reasons of structural stability and improved magnetic return, the cross-section in the transition element is continuously increasing. The continuous increase may have a non-linear shape, such as a sine or cosine shape, or a circular or cubic shape, or any other non-linear shape. Due to the ease of manufacture and, as has been found, optimal functionality for the magnetic inference, however, it is preferred that the course of the cross-sectional increase or the decrease in cross-section in the transition region is linear.

Furthermore, it is preferred that in the middle region in which the permanent magnets are arranged, upwards or downwards with respect to the permanent magnets, ie adjacent to the permanent magnets, a free area with a height on each side, which is at least greater than one millimeter. For more precise placement of the permanent magnets, the area next to the permanent magnets can furthermore have a slightly smaller inner diameter than the area in which the permanent magnets are arranged directly. Then, an accurate placement of the permanent magnets can be achieved. On the other hand, it can be ensured by the regions above and below the permanent magnets, which are still formed with almost or identically large inner diameter of the magnetic return element, that the magnetic return element, which so to speak, extends over the motor gap or over the permanent magnets, does not lead to a magnetic short circuit, but only the Rückschlussfunktionalität satisfied and at the same time contributes to the mechanical stabilization of the return element. Likewise, this height is well filled with the second coating so that a highly effective heat sink is formed around the permanent magnets to dissipate the heat as quickly as possible into the already highly thermally conductive magnetic return element, while still providing this heat sink, the second coating is at least significantly thermally insulated by the first coating from the motor gap.

• 1 eine schematische Draufsicht auf einen Elektromotor mit Rotor und Stator in Außenläuferkonstruktion;
• 2 eine schematische Seitenansicht eines Elektromotors mit Rotor und Stator gemäß dem ersten Aspekt der thermischen Abschirmung;
• 3 eine schematische Darstellung der Ausführung der ersten und zweiten Beschichtung aus einem gleichen Grundmaterial und unterschiedlicher Füllkörperdichte;
• 4 eine schematische Schnittdarstellung eines Rotors in Außenläuferkonstruktion mit einem U-förmigen magnetischen Rückschlusselement;
• 5 eine schematische Schnittdarstellung eines Rotors für einen Elektromotor mit thermischer Abschirmung gemäß dem ersten Aspekt und U-förmigem magnetischen Rückschlusselement gemäß dem zweiten Aspekt in Kombination zueinander;
• 6 eine perspektivische schematische Darstellung eines Rotors für einen Elektromotor gemäß dem zweiten Aspekt mit U-förmigem magnetischen Rückschlusselement ohne Verwendung der wärmeabschirmenden Beschichtung;
• 7 eine schematische Darstellung eines Magnetlagers am Beispiel eines Innenläufers mit außenliegendem Stator und Permanentmagneten am innenliegenden Rotor; und
• 8 einen schematischen Querschnitt für eine Wärmepumpe mit einem Elektromotor, der den erfindungsgemäßen Rotor aufweist.

Preferred embodiments of the present invention will be explained below in detail with reference to the accompanying drawings. Show it:

• 1 a schematic plan view of an electric motor with rotor and stator in external rotor design;
• 2 a schematic side view of an electric motor with rotor and stator according to the first aspect of the thermal shield;
• 3 a schematic representation of the execution of the first and second coating of a same base material and different packing density;
• 4 a schematic sectional view of a rotor in outer rotor design with a U-shaped magnetic yoke element;
• 5 a schematic sectional view of a rotor for a thermal shielding electric motor according to the first aspect and U-shaped magnetic return element according to the second aspect in combination with each other;
• 6 a perspective schematic representation of a rotor for an electric motor according to the second aspect with U-shaped magnetic return element without using the heat-shielding coating;
• 7 a schematic representation of a magnetic bearing on the example of an internal rotor with external stator and permanent magnets on the inner rotor; and
• 8th a schematic cross section for a heat pump with an electric motor having the rotor according to the invention.

1 shows a rotor 1 and a stator 200 between which a motor gap 40 is arranged. In particular, the rotor comprises 1 a plurality of permanent magnets attached to each other 11 . 12 . 13 . 14 , Each permanent magnet of the plurality of permanent magnets 11 . 12 . 13 . 14 has a north pole and a south pole. In particular, in the in 1 shown four permanent magnets arranged, in such a way that the motor gap towards the north pole and south pole of the annular permanent magnets or the circular sector-shaped permanent magnets alternate, as shown schematically in FIG 1 is marked with N for north and S for south. The stator 200 lies over the engine gap 400 opposed to the permanent magnet, but with the heat-shielding first coating 20 is arranged on the sides of the permanent magnets facing the motor gap, this heat-shielding first coating having a first (low) thermal conductivity.

2 shows a cross section through the arrangement of 1 in a schematic manner, wherein in particular the permanent magnet 14 is cut. It is specifically stated that the heat-shielding first coating 20 on the permanent magnet 14 is arranged and this from the engine gap 40 thermally insulated. In addition, a second coating 30 disposed in contact with a respective other side of the plurality of permanent magnets. In particular, the second coating has a thermal conductivity that is greater than the first thermal conductivity. The other side of the plurality of permanent magnets is in the in 2 shown embodiment, the upper flat side 15a or the lower flat side 15b , Preferably, the permanent magnet 14 embedded so that the side facing the motor gap 15c surrounded by the first coating is that the upper and lower small side 15b are embedded in the second coating or are touched by the second coating, and that the fourth side 15d of the permanent magnet rests on a support structure, such as a magnetic return element 202 , Furthermore, the support structure in addition to the magnetic return element 202 another bandage, such as a carbon bandage 203 include in 2 not shown, however, in 5 or 8th is shown.

The first coating has a low thermal conductivity, such as a thermal conductivity of λ = 0.25 watts / Km. In contrast, the second coating has a higher thermal conductivity, such as a four times as large thermal conductivity of λ = 2 W / Km. However, it is already achieved a positive effect in that the low thermal conductivity of the first coating is less than 1 W / Km, and that the high thermal conductivity is greater than 1.1 W / Km. The greater the difference between the thermal conductivities, and the smaller the total value of the thermal conductivity of the first coating, the better the heat shield on the one hand and the dissipation of the heat still passed through the first coating on the other hand from the permanent magnets 14 be.

Furthermore, in the in 2 schematically shown a coil 16 indicated in cross-section, around a pole foot 17 of the stator 200 is wound and together with the permanent magnet 14 and of course together with the other permanent magnets 14 and the other coil provides the electric motor effect.

3 shows a preferred embodiment for the preparation of the two layers 20 . 30 , Both layers 20 . 30 are preferably formed of the same basic material. In the first coating 20 However, there are no or only a very small number of thermally conductive fillers. In the second coating 30 In contrast, there are a larger number or a very large number of thermally conductive fillers. Thus, the heat from the motor gap from the permanent magnet 14 kept away, by the action of the first coating 20 while the heat is optimal from the permanent magnet 14 through the second coating 30 is led away. The base material used is preferably epoxy resin, which, without a special filling, has a relatively low thermal conductivity. The relatively low thermal conductivity of epoxy resin in the range of 0.25 W / Km can be increased by introducing conductive fillers, such as ferritic powder, so that the thermal conductivity of the second coating 30 can be brought into ranges of 2 W / Km.

One way of making the two coatings in 3 begins with the attachment of non-magnetized permanent magnets 14 on a return element 200 , The magnets 14 For example, on the return element 202 be glued, preferably with good thermal conductivity adhesive and of course with a material that is magnetically conductive. Then the layer of epoxy resin is applied, with a relatively uniform distribution of the packing 25 in the layer. Then an external magnetic field is applied by the return element, sector by sector, around the individual permanent magnets 14 to magnetize. As a result of the magnetic fields applied to magnetize the permanent magnets, the ferritic, but also magnetically well-conducting filling bodies are now drawn toward the inference element. Due to the toughness of the base material, the filler gradually migrates towards the return element due to the externally applied magnetic field, resulting in a distribution of packing in the base material. The result is an area with a small number of packing away from the return element, which is the first coating 20 represents, while many fillers close to the inference element 202 are arranged to form the second good thermal conductivity coating. At the end of this manufacturing process, both the packing is properly placed and has the magnetization of the permanent magnets 14 occurred. Once the resin material has fully cured, the first and second coatings are 20 . 30 completed. It can be seen that between the first and the second coating one or more further layers can be, or a continuous transition of the materials and properties can be.

4 shows a cross section through a rotor 1 according to the second aspect, ie the U-shaped magnetic return element. The magnetic return element 202 is at the in 4 shown embodiment designed as an external rotor rotor element and is in particular annular, as it is z. In 2 can be seen, but also in 6 , The magnetic return element comprises a first region a with a first inner diameter, a second region 202b with a second inside diameter and a third area 202c with a third inner diameter. In the second area 202b is the majority of permanent magnets 14 . 11 . 12 . 13 from 1 arranged. As it is in 4 is shown, is the second inner diameter of the second region 202b larger than the first inner diameter of the first region 202a and larger than the third inner diameter of the third region 202c , In addition, the third inner diameter is in the third range 202c larger than the first inner diameter in the first area 202a , This ensures that as much material as possible of the magnetic return element is as close as possible to a rotation axis which is in 4 at 206 is shown is arranged. It should be noted that the schematic representation in FIG 4 should represent a schematic cross section, the axis of rotation 206 is symmetrical. However, it is essentially the left part of the cross section in FIG 4 shown. However, the right part of the cross section would be a mirror image. Further, the inner diameters D1 . D2 . D3 drawn, wherein the inner diameter D2 the largest is, and where the inner diameter D1 the smallest is on the side of the magnetic return element 202 at which the area to be rotated 105 how the radial wheel is arranged, for example.

This ensures that as much material as possible of the magnetic return element, as in 4 can be seen, as far as possible inside, so close to the axis of rotation 206 is arranged. At the same time, however, is due to the smaller diameter D3 ensures that the rotor can still be mounted without the magnetic return element 202 to carry out in several parts. For this purpose, the rotor can be moved from bottom to top to align the stator with the permanent magnet, or it can be used from above into the rotor from the stator to the stator 200 as it is in 4 is shown with the permanent magnets, such as the magnet 14 align to the engine gap 40 to build.

5 shows a preferred embodiment of the present invention, wherein the first aspect with respect to the coatings with heat-shielding material on the one hand and thermally conductive material on the other hand with the cross-sectionally U-shaped return element 202 combined. At the in 5 illustrated embodiment can be seen that the central region 202b has a height that is around a certain free height 207 is greater than a height of the permanent magnet 14 , Preferably, the free height 207 above and below the permanent magnet 0.75 mm upward with respect to the central area 202b and down with respect to the middle area 202b trained as it is through 207 is shown.

In particular, the plurality of permanent magnets are so in the middle region 202b arranged so that the central region extends at least 0.5 mm on each of the two sides beyond the permanent magnet of the plurality of permanent magnets. In one implementation, the middle range is 202b furthermore, as at 209 in 5 is shown formed such that a small cross-sectional crack 209 is arranged. This is the permanent magnet 14 inserted a little deeper into the magnetic recoil element as the dimension in the free height 207 is trained. In particular, in the second region of the permanent magnet is disposed in a region in which the inner diameter is larger by at least 0.1 mm than the inner diameter of the second region above and below the permanent magnet, as in the two central regions 207 , As an alternative for the cross-section jump 209 could also be provided a cross-sectional difference of greater than 0.5 mm or perhaps even 1 mm, depending on the embodiment.

Furthermore, the magnetic return element is 202 as it is in 5 shown with a bandage 203 provided to achieve further stabilization against the high centrifugal forces, which act when the rotor at high angular velocity about the axis of rotation 206 rotates.

In addition, at the in 5 shown preferred embodiment of the magnetic return element, a first transition region 202d and / or a second transition area 202e intended. The first transition area is between the first area 202a and the second area 202b intended. The second transition area 202e is between the middle and second area 202b and the third or upper area 202c intended. The first transition area 202d and the second transition area 202e each have a continuously decreasing inner diameter from the second inner diameter to the first inner diameter for the first transition region 202d or from the second inner diameter to the third inner diameter for the second transition region 202e , As it is in 5 is shown, it is preferred that the continuously decreasing inner diameter decreases linearly, both in the second transition region 202e as well as in the first transitional area 202d , Other nonlinear inner diameter decreases and a linear inner diameter decrease in the second transition region and a nonlinear inner diameter decrease in the first transition region may also be used, but the linear inner diameter decreases are preferred.

As it is in 5 Further, the first coating is shown 20 again on the permanent magnet 14 arranged and shields this from the engine column 40 or from the heat present therein. In addition, the second coating 30 now arranged such that they the region in the second transition region and in the central region between the first coating and the magnetic return element 202 fills. This is the second coating 30 , which has a high thermal conductivity, even in good contact with the upper side surface 15a and the lower side surface 15b of the permanent magnet and thus can heat, despite the first coating in the magnet 14 has been introduced to the magnetic return element 202 Derive, which represents a relatively good heat sink, because it out ferromagnetic material, such as iron is formed.

Furthermore, it is off 5 can be seen that the first coating is continuous, so that the rotor through a smooth surface to the motor gap 40 is delimited.

Further, it is preferable that between the permanent magnet 14 and the first coating 20 no second coating is arranged, but that the second coating is adjacent to the permanent magnet and there under the first coating. Further, it is preferable that at least on the lower portion 202a neither a first nor a second coating is applied. In addition, also in the upper area 202c a first coating 20 be arranged. In one implementation, however, no first coating may be disposed even in the upper region if the upper region is far enough away from the motor gap 40 is removed, so that a heat input into the magnetic return element 202 does not take place or is uncritical.

In addition, it is preferred that just the inner diameter of the lower portion 202a of the magnetic return element is the smallest inner diameter, so that the surface of the magnetic return element, on the region to be rotated, ie on the Radialrad 105 is set as large as possible in order to achieve a good attachment. Further, as also shown in the figures, the inner diameter is in the first region 202a definitely smaller than the outer diameter of the stator 200 , This is not a problem because the third inner diameter is larger than the outer diameter of the stator, so that rotor and stator can still be mounted without the magnetic return element 202 would have to be executed in several parts, which is not favorable for reasons of stability. Moreover, it is preferred that the first inner diameter be at least 10% smaller than the second inner diameter, although smaller first inner diameters may be used for the magnetic return element, depending on the embodiment.

The third inner diameter in the third upper area 202c is at least 3% smaller than the second inner diameter. Depending on the implementation, the thickness in the cross section of the first region, that is, between the first coating, is thus also 20 and the right edge of the bandage 203 in 5 greater than a thickness in the cross section of the magnetic return element in the second region plus a thickness in the cross section of the permanent magnet of the plurality of permanent magnets. Although in 5 In the case where the thickness in the third region is approximately equal to the thickness in the cross section of the magnetic return element plus the permanent magnet, it is preferred in other embodiments that the third upper region is also slightly above the permanent magnet 14 protrudes.

Further, in a preferred embodiment, the first thickness of the first coating is 20 on the side facing the engine gap side of the plurality of permanent magnets between 1 micron and 100 microns thick. Alternatively or additionally, the second thickness of the second coating 30 greater than the first thickness and less than or equal to the thickness in cross section, the permanent magnet of the plurality of permanent magnets. As it is in 5 is shown, the thickness of the second coating in the central region and in particular in the "free height" of the central region 207 slightly smaller than the thickness of the permanent magnet because the permanent magnet is somewhat inserted due to the stepped cross section, as in 209 is shown. If this depression at 209 is not present, then the thickness of the second coating would be 30 in the middle free area 207 equal to the thickness of the permanent magnet.

In one implementation, the number of permanent magnets is an even number greater 2 , in which in 6 shown embodiment, a total of four permanent magnets are arranged, but also with arrangements 6 . 8th . 10 . 12 . 14 . 16 , etc. permanent magnets can also be used, with the correspondingly increased number of coils on the pole feet of the stator. Moreover, it is preferable to uniformly arrange the permanent magnets over the circular ring such that each permanent magnet is formed in a circular arc, and that the magnetization directions of adjacent permanent magnets are opposite to each other.

Furthermore, it is preferred that the height of the magnetic return element is between 3 and 5 cm, or that a diameter of the motor gap 40 between 6 and 10 cm.

6 shows a schematic view of the element to be rotated 105 on which the magnetic return element 202 is arranged, which of the bandage 203 is secured. In addition, circular arc-shaped permanent magnets 11 . 12 . 13 shown, wherein the rotor together with rotating section in 6 is cut for illustrative purposes, such that on the cut side of the fourth permanent magnet 14 would be arranged. Furthermore, in 6 to see that the inner diameter of the upper area 202c , the middle area 202b and the lower part 202a are different from each other, and that the permanent magnets in the middle area are arranged. In addition, the transition areas are also 202d and 202e in 6 can be seen in which the inner diameter continuously merge into one another. In addition, it is also shown that in the middle region, the "free height 207" above and below the plurality of permanent magnets are present, so that the magnetic return element does not lead to a magnetic short circuit.

While at the 1 to 6 an external rotor is shown 7 an implementation of the present invention as an internal rotor. There are the stator 200 outside and the rotor 1 formed inside, being between the two elements of the motor gap 40 is arranged.

Preferably, the rotor is supported relative to the stator by a magnetic bearing, as exemplified in US Pat 7 is shown. In 7 the two directions are axial 250 and radial 260 located. There is again a motor with a motor gap 40 and the rotor is held axially with respect to the stator due to the permanent magnets on the side of the rotor and the electrical coils on the side of the stator and not specifically regulated. Furthermore, in 7 a radial detection device 270 and a radial control device 280 intended. The radial detection device 270 includes the position of the rotor with respect to the stator and vice versa via detection lines 271 , The result of the radial detection is via a sensor line 272 the radial control / regulation device 280 communicated. This generates correspondingly the actuator signals via Aktorsignalleitungen 273 on the rotor or the stator depending on the implementation. However, it is preferred to drive only the rotor to position it relative to the stator due to the actuator signal, such that the motor gap 40 around the entire rotor has a similar size and the rotor does not touch the stator.

At the in 7 embodiment shown is the rotor 1 inside and is the stator 200 arranged outside. This is thus an internal rotor in contrast to, for example 3 . 4 , or 5. The appropriate control / regulation by the elements 270 . 280 . 271 . 272 . 273 However, this can also happen with an outrunner. In principle, however, the magnetic bearing on the example of in 7 In both cases, the reluctance bearing shown similar in that an axial control does not take place, while a radial control by the radial detection means 270 and the radial controller 280 takes place.

8th shows a preferred application of the pancake motor on the example of a heat pump. The heat pump includes an evaporator 300 , a compressor 400 and a liquefier 500 , where the compressor 400 having the electric pancake motor, the reference to the 1a to 5 has been described.

In addition to the elements of the pancake motor illustrated, for example, with reference to one of the preceding figures, the compressor further comprises a void space 410 which is arranged radially to that of the element to be moved 105 funded working steam coming from the evaporator 300 has been sucked in, further and finally the pressure to the required pressure in the condensation zone 510 in the condenser 500 to increase.

Liquid to be cooled passes through an evaporator inlet 302 in the evaporator. Cooled working fluid passes through an evaporator outlet 304 again from the evaporator. To make sure the radial wheel 105 only steam and not water drops in addition to the steam sucks, is also a mist eliminator 306 intended. Due to the low pressure in the evaporator 300 becomes part of the over the evaporator feed 302 in the evaporator 300 brought working fluid evaporated and through the mist eliminator 306 through the second page 105b of the radial wheel 105 sucked and conveyed up and then into the Leitraum 510 issued. From the Leitraum 510 becomes compressed working steam in the condensation zone 510 brought. The condensation zone 510 is also via a condenser feed 512 supplied to be heated working fluid, which is heated by the condensation with the heated steam and a condenser 514 is dissipated. Preferably, the condenser is designed as a condenser in the form of a "shower", so that via a distribution device 516 a liquid distribution in the condensation zone 510 is reached. Thus, the compressed working steam is condensed as efficiently as possible and the heat contained in it is transferred into the liquid in the condenser.

At the in 8th embodiment shown is also a motor housing 110 located at the same time, the upper housing part of the condenser or condenser 500 forms. In addition, a connection cable 80 for the coils of the stator 200 with a controller 600 connected to perform the appropriate speed controls and at the same time the active storage on a preferably used magnetic bearing, as shown by 7 has been described. The controller thus also provides the functions of radial detection 270 and the radial control / regulation 280 ready.

In addition, in 8th an implementation shown in which the pancake motor a firmly potted block 602 made of potting material, which has a sealing ring 603 with respect to the motor housing 110 is sealed so that a pressure-tight separation between the exterior and the interior takes place. Both the bobbin holder and the coils are surrounded by an encapsulation material that is in 8th as integral with the solid block 602 is shown formed. However, this does not necessarily have to be the case. However, it is preferable to cause separation by the encapsulant material extending in the motor gap, so that the coils are not disposed in the low pressure area provided inside the motor housing.

Furthermore, in the in 8th shown embodiment, the stator disposed in a recess which through an upper side 105a is defined. In other embodiments, however, the rotor may be formed without a recess, so that the region of magnet 201 , Return element 202 and bandage 203 as he is in 8th is shown, is placed on a top flat shaped radial wheel.

Out 8th It can also be seen that the element to be moved, with the rotor 10 is connected, the radial wheel or impeller 105 that is there to work in conjunction with the route 410 To compress and heat the working steam conveyed by the evaporator so that heat is pumped from the evaporator to the condenser.

Hereinafter special embodiments are summarized in particular for a two-part stator, but also for a one-piece stator.

Although certain elements are described as device elements, it should be understood that this description is likewise to be regarded as a description of steps of a method and vice versa.

It should also be noted that a control, for example, by the element 600 in 8th can be implemented as software or hardware. The implementation of the controller may be on a non-volatile storage medium, digital or other storage medium, in particular a floppy disk or CD with electronically readable control signals that may interact with a programmable computer system to perform the corresponding method of operating a heat pump. In general, the invention thus also comprises a computer program product with a program code stored on a machine-readable carrier for carrying out the method when the computer program product runs on a computer. In other words, the invention can thus also be realized as a computer program with a program code for carrying out the method when the computer program runs on a computer.

LIST OF REFERENCE NUMBERS

1

rotor

11

permanent magnet

12

permanent magnet

13

permanent magnet

14

permanent magnet

15a

Top of the permanent magnet

15b

Bottom of the permanent magnet

15c

to the motor gap facing side of the permanent magnet

15d

from the motor gap facing away from the permanent magnet

16

Kitchen sink

17

pole foot

20

first coating

25

filler particles

30

second coating

40

motor gap

105

area to be turned (e.g., radial wheel)

200

stator

201

permanent magnet

202

magnetic return element

202a

first area

202b

second area

202c

third area

202d

first transition area

202e

second transition area

203

bandage

207

free height

209

gradation

250

axially

260

radial direction

270

Radial detector

271

sense line

272

control line

273

actuator cable

280

Radial-control / regulation device

300

Evaporator

302

evaporator feed

304

evaporator flow

306

Droplet

400

compressor

410

route

500

condenser

510

condensation zone

512

Verflüssigerzulauf

514

Verflüssigerablauf

516

Verflüssigerverteiler

600

control

602

stator block

603

sealing ring

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 2549113 A2 [0002]
• EP 2975731 A2

Claims (29)

Rotor for an electric motor with a motor gap (40), having the following features: a plurality of permanent magnets (11, 12, 13, 14); and an annular magnetic yoke element (202), wherein the rotor is designed as an external rotor rotor, wherein the magnetic return element (202) has a first region (202a), a second region (202b) and a third region (202c), the first region (202a) having a first inner diameter, wherein in the second region (202b) the plurality of permanent magnets (14) is arranged, and wherein the second region has a second inner diameter, wherein the third region has a third inner diameter, and wherein the second inner diameter is larger than the first inner diameter and the third inner diameter, and wherein the third inner diameter is larger than the first inner diameter, and wherein the third inner diameter is larger than an outer diameter of a stator (200) for the electric motor. Rotor after Claim 1 in that the central region (202b) has a height which is at least 1.5 mm greater than a height of a permanent magnet (11-14), wherein the plurality of permanent magnets are arranged in the middle region (202b) such that the central region extends at least 0.5 mm on each of two sides (207) beyond a permanent magnet (11-14) of the plurality of permanent magnets, or in which the second region (202b) is in the region in which the permanent magnets are arranged , an inner diameter that is less than one mm larger (209) than the inner diameter of the second region above or below (207) of the plurality of permanent magnets (14). Rotor after one of Claims 1 or 2 wherein the magnetic return element has a first transition region (202d) between the second region (202b) and the first region (202a) or a second transition region (202e) between the second region (202b) and the third region (202c) the first transition region or the second transition region has a continuously decreasing inner diameter from the second inner diameter to the first inner diameter and the third inner diameter, respectively. Rotor after Claim 3 in which the continuously decreasing inner diameter decreases linearly. Rotor according to one of the preceding claims, further comprising: a first coating (20) disposed on the sides (15c) of the permanent magnets (11-14) facing the motor gap (40), the first coating (20) having a first thermal conductivity; and a second coating (30) in contact with a respective other side (15a, 15b) of the plurality of permanent magnets (11-14), the second coating (30) having a second thermal conductivity greater than the first thermal conductivity , Rotor after one of Claims 1 to 5 in which the second coating (30) is arranged in the second region (202b) next to the permanent magnets of the plurality of permanent magnets (11-14) and in the first or second transition region (202d, 202e), and in which the first coating (202) 20) is continuous and is arranged on the side of the permanent magnet facing the motor gap and on the second coating (30). Rotor after Claim 6 in which no second coating (30) is applied to the third region (202c) or the first region (202a). Rotor after one of Claims 1 to 7 wherein the first portion (202a) of the magnetic return element (202) is connected to a portion (105) of the rotor (1) to be rotated, and wherein the first inner diameter of the first portion (202a) is smaller than an outer diameter of a stator (200) ) for the electric motor and is at least 10% smaller than the second inner diameter. Rotor after one of Claims 1 to 8th in which the third inner diameter is at least 3% smaller than the second inner diameter or has a thickness in cross section greater than a thickness in the cross section of the magnetic return element (202) in the second region plus a thickness in the cross section of a permanent magnet (14) the plurality of permanent magnets (11-14). Rotor after one of Claims 1 to 9 in which a first thickness of the first coating (20) on the side of the plurality of permanent magnets facing the motor gap (40) is between 1 μm and 100 μm or a second thickness of the second coating (30) is greater than the first thickness or is less than or equal to the thickness in the cross section of the permanent magnets of the plurality of permanent magnets. Rotor after one of Claims 5 to 10 in which between the first coating (20) and the Plurality of permanent magnets (14) no second coating (30) is arranged. Rotor according to one of the preceding Claims 1 in that the plurality of permanent magnets (11-14) are arranged so that the sides (15c) facing the motor gap (40) provide a circular space in which a stator can be mounted to between the stator (200) and the stator Rotor (1) to form the motor gap (40) with an annular shape. A rotor as claimed in any one of the preceding claims, wherein the second coating (30) is disposed between the other side (15a, 15b) of the permanent magnet and a surface of the magnetic return element (202), the other side (15a, 15b) of the other Permanent magnet is a third or a fourth side of the permanent magnet, which is not the side facing the motor gap and not the side facing away from the motor gap of the permanent magnet. Rotor according to one of the preceding claims, wherein the magnetic return element (202) is annular and has an annular recess (202b) on an inner side in which the plurality of permanent magnets (11-14) are disposed, with a lower (202a) or upper (202c) boundary the recess extends beyond the side of the permanent magnet associated with the motor gap, and wherein the recess (202b) is dimensioned such that between the upper boundary of the recess or between the lower boundary of the recess and a corresponding permanent magnet, the second coating (30) is arranged. Rotor after one of Claims 5 to 14 in which the first coating (20) is additionally arranged on the second coating (30), and further in the region of the respective other side (15a, 15b) of the plurality of permanent magnets, or in which the first coating (20) is so is designed to have a thermal conductivity less than 0.9 W / Km or the second coating is formed so that it has a thermal conductivity greater than 1.1 W / Km. Rotor after one of Claims 5 to 15 in which the first coating (20) and the second coating (30) are formed from the same base material, wherein in the first coating, no or a first number of thermally conductive filler bodies (20) is arranged and in the second coating, a second number of thermally conductive Fillers (25) is arranged, wherein the second number is greater than the first number or greater than zero, or wherein a density of packing in the first coating is smaller than a density of packing in the second coating, and wherein a thermal conductivity of the filling material is greater than a thermal conductivity of the base material. Rotor after Claim 16 in which the base material is a resin material and the filler bodies (25) comprise a powder of a material which has a higher thermal conductivity than the base material, or in which the powder (25) comprises a ferritic material. Rotor according to one of the preceding claims, wherein the magnetic return element has a third thermal conductivity, which is greater than the first thermal conductivity and / or greater than the second thermal conductivity. A rotor as claimed in any one of the preceding claims, wherein the magnetic return element (202) is surrounded by a circumferential stabilizing bandage (203) on a side where the plurality of permanent magnets are not disposed. Rotor according to one of the preceding claims, wherein the magnetic return element (202) is connected at a first end to a portion (105) of the rotor to be rotated, the first end projecting beyond the plurality of permanent magnets (11-14), and wherein a second end of the magnetic return element (202) is dimensioned such that an inner diameter of the magnetic return element is larger than an outer diameter of a stator (200) for the electric motor. Rotor after Claim 20 wherein a distance that the magnetic return element projects beyond the plurality of permanent magnets in the first region (202a) is greater than or equal to a thickness of the first coating (20) on the plurality of permanent magnets. A rotor according to any one of the preceding claims, wherein a number of the permanent magnets (11-14) is an even number greater than 2, each permanent magnet being arcuate in shape and having a direction of magnetization on the side facing the motor gap that faces a magnetization direction of an adjacent permanent magnet the opposite side of the motor gap is directed. Rotor according to one of the preceding claims, wherein the first coating (20) so is formed such that a surface of the first coating towards the motor gap (40) is a smooth surface. A rotor according to any one of the preceding claims, wherein a height of the magnetic return element (202) is between 3 and 5 cm or a diameter of the motor gap (40) is between 6 and 10 cm. Method for producing a rotor for an electric motor with a motor gap (40), comprising the following steps: Producing an annular magnetic return element (202), wherein the magnetic return element (202) has a first region (202a), a second region (202b) and a third region (202c), wherein the first region (202a) has a first inner diameter, wherein the second region has a second inner diameter, the third region having a third inner diameter, wherein the second inner diameter is greater than the first inner diameter and the third inner diameter, wherein the third inner diameter is greater than the first inner diameter, and wherein the third inner diameter is larger as an outer diameter of a stator (200) for the electric motor; and Arranging the plurality of permanent magnets in the second region (202b). is, wherein the rotor is designed as an external rotor rotor, Electric motor comprising: a stator (200); and a rotor (1) according to one of Claims 1 to 24 which opposes the stator via a motor gap (40). Electric motor after Claim 26 in which the rotor (1) is actively magnetically supported radially with respect to a rotational axis of the rotor, or in which the rotor is axially magnetically passive with respect to a rotational axis of the rotor. Electric motor after Claim 26 or 27 wherein the rotor (1) is integrally formed or connected to a member to be moved, wherein the member (105) to be moved is a radial wheel with vanes, the vanes being configured to receive gas from an area upon rotation of the radial wheel To promote lower pressure in an area with a higher pressure. Heat pump having the following features: an evaporator (300); a compressor (400); and a condenser (500), wherein the compressor (400) comprises an electric motor according to any one of Claims 26 to 28 having.

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