Motor

Abstract

An electric machine comprises: a stator (1) having a stator body (25) supporting an electric stator (3); and a rotor (5). The rotor (5) is supported by means of a bearing comprising a radial bearing section (17) forming a radial gas bearing and an axial bearing section (12) forming an axial gas bearing, the stator side parts of these bearing sections being a stator side radial bearing section and a stator side axial bearing section rigidly connected to each other and jointly forming a stator bearing structure. The stator side radial bearing section is a bushing (18) and is radially surrounded by a cooling body (71), and the bushing (18) is connected to the cooling body (71) by an elastic support member comprising a heat conductive filler (23).

Description

Technical Field

[0001] The present invention relates to the field of motors, in particular to a high-speed motor with a gas bearing. Background Art

[0002] An electric motor typically includes a rotor and a stator including a stator body that supports and houses the electric stator and bearings. The position of the bearings relative to the stator body may be defined by a bearing flange of the stator body. Typically, there are two journal bearings, typically located at opposite sides of the stator, such as Figure 1a The arrangement shown in FIG. 1 is shown in FIG. 1 (in which the stator body is not shown). In this case, the alignment accuracy of the bearing is mainly defined by the machining accuracy of the bearing flange and the stator body. For fluid films, and especially for gas bearings, accurate alignment is critical, and the arrangement generally requires special measures such as self-aligning or compliant bushing installation, or machining such as reaming of the bearing pair after assembly. Alternatively, the journal bearings can be arranged on the same side of the stator. This arrangement is often referred to as an overhung motor design ( Figure 1b ). With an overhang design, the two journal bearings can be integrated into a single part, so it is easier to achieve precise bearing alignment. However, this approach usually results in a longer rotor and therefore a more critical dynamic behavior of the rotor. In addition, windage losses caused by air resistance increase, negatively affecting overall motor efficiency.

[0003] US 3'502'920 discloses a slotted electric machine with an air-gap bearing, in which a bushing is located in the magnetic gap between the stator and the rotor. The bushing can be suspended elastically relative to the stator. It defines a radial bearing on the one hand and can include a centrally located thrust bearing or thrust block as an axial bearing. In order to assemble the machine, the rotor needs to be separated in the axial direction. This design is not suitable for high-speed motors.

[0004] WO 03 / 019753 A2 shows a spindle motor in which a rotor rotates in a stator within a thin layer of epoxy resin which forms a cylindrical through hole in the stator and serves to define both radial and axial bearing surfaces. The thin layer of epoxy resin is directly coupled to the stator housing and any thermally induced deformation of the housing immediately affects the bearing geometry.

[0005] US 2006 / 0061222 A1 and US 2006 / 0186750 A1 show conventional air bearings.

[0006] WO 2017 / 202941 A1 discloses an electric machine and an associated rotor, which solve the above problems by supporting the rotor with the help of radial bearing segments forming radial gas bearings and axial bearing segments forming axial gas bearings, the stator side parts of these bearing segments being stator side radial bearing parts and stator side axial bearing parts rigidly connected to each other and jointly forming a stator bearing structure. The stator side radial bearing part or the stator side axial bearing part is rigidly mounted to other parts of the stator, and the corresponding other parts are elastically supported or not supported at all. All or part of the radial bearing segment is located in the magnetic gap between the electric stator and the rotor. It is obvious that it is necessary to transfer heat from windage losses (caused by the relative movement of the rotor in the stator bore and by the relative movement of the bearing surface and the air in the air bearing) and electromagnetic losses, for example, out of the rotor and the bearings. Summary of the invention

[0007] One possible object of the present invention is therefore to create an electric machine of the above-mentioned type that overcomes the above-mentioned disadvantages.

[0008] Another possible object of the invention is to simplify the design of an electric machine of the initially mentioned type. This can improve mechanical stability, manufacturability and machine quality.

[0009] At least one of these objects is achieved by an electric machine described below.

[0010] According to a first aspect of the present invention, an electric machine comprises: a stator having a stator body supporting an electric stator; and a rotor. The rotor is supported by means of a bearing comprising a radial bearing section forming a radial gas bearing and an axial bearing section forming an axial gas bearing, the stator side parts of the bearing sections being a stator side radial bearing section and a stator side axial bearing section rigidly connected to each other and jointly forming a stator bearing structure. The stator side radial bearing section is a bushing, and the bushing is radially surrounded by a cooling body, and the bushing is connected to the cooling body by an elastic support comprising a heat conductive filler.

[0011] Typically, the heat-conducting filler is in contact with both the bushing and the cooling body along the section of the axial length of the bushing where the radial bearing section is present.

[0012] This allows efficient transfer of heat out of the stator bearing structure, in particular out of the bushing.The elastic support allows compensating possible deformations of the stator parts, for example by thermal expansion, and improves the vibration characteristics.

[0013] Thermal coupling of the bushing to the stator can be achieved by using O-rings, which serve both as flexible support elements and for sealing a thermally conductive filler placed between the O-rings. As in a squeeze film damper, the filler can have a damping effect, depending on its viscosity.

[0014] Thermally conductive fillers are usually deformable materials, especially,

[0015] Solids, such as silicone or silicone foam; or

[0016] Fluid or flowable materials, such as pastes or gels; in particular

[0017] • Liquids, such as oils with additives.

[0018] The thermally conductive filler may absorb relative movements between the bushing and the cooling body, and / or compensate for possible deformations of the parts, while maintaining physical contact and providing a thermally conductive connection between the bushing and the cooling body.

[0019] In the present context, thermal conductivity means a thermal conductivity of at least 0.5 W / °K / m or at least 1 W / °K / m or at least 2 W / °K / m or at least 4 W / °K / m.

[0020] In an embodiment, the bushing is radially surrounded by the cooling body and is thermally coupled to the cooling body via the heat-conducting filler over at least 20% or 40% or 60% or 80% of the axial length of the bushing.

[0021] The heat-conducting filler is usually arranged in the gap between the cooling body and the bushing.

[0022] In an embodiment, the stator bearing structure extends from a first end to a second end in the axial direction of the motor, and the stator bearing structure is rigidly supported by other parts of the stator near one of the two ends and is elastically supported or not supported at all near the other end.

[0023] Therefore, the above-mentioned “other parts” may be the stator body itself, or an assembly including the electric stator and the carrier, the assembly being elastically supported by the stator body.

[0024] The axial direction corresponds to the axis of rotation of the rotor and shall also be referred to as longitudinal direction.

[0025] In an embodiment, the stator bearing arrangement is mounted to other parts of the stator by a stator-side axial bearing part, in particular an axial bearing assembly, which is rigidly mounted to these other parts.

[0026] As a result, the stator bearing structure is suspended at one end by the axial bearing portion, and the remainder of the stator bearing structure is elastically suspended (which eliminates or reduces mechanical stresses), but is still thermally coupled to the cooling body.

[0027] Journal bearings can be integrated into a single section, so precise alignment is easier to achieve than with journal bearings on separate sections.

[0028] In an embodiment, the radial bearing segment extends in the longitudinal direction of the rotating shaft and all bearing elements of the radial bearing segment and the mating rotor bearing surface are located outside the magnetic gap between the electric stator and the rotor.

[0029] In other words, this means that the electric machine is of the overhung type, that is to say that, viewed from the longitudinal axis of the machine, the journal bearings or bushings and the cooling body are located at a different position than the electric stator and the permanent magnets, respectively.

[0030] In an embodiment, the radial bearing segment extends in the longitudinal direction of the rotating shaft and at least 60% or 70% or 80% or 90% of the radial bearing segment is located outside the magnetic gap between the electric stator and the rotor.

[0031] Here and throughout this document, the terms “rigid” and “fixed” are used instead of “elastic.” An elastic connection has a spring stiffness or Young's modulus that is at least, for example, 100 or 10,000 or 1,000,000 times greater than a rigid connection.

[0032] A rigid connection is a connection designed so that the connected parts do not move relative to each other during normal operation of the machine. Thus, a rigid connection can be established by screwing the parts together or by pressing the parts against each other with a spring. In this case, the spring is not part of the rigid connection, but provides a force that keeps the connection rigid.

[0033] The elastic support may be an O-ring, usually made of (synthetic) rubber or a metal spring.

[0034] The term "high speed motor" is used to cover machines suitable for speeds above 100,000 revolutions per minute.

[0035] The gas of the gas bearing may be any gas in which the machine operates, such as air, coolant, natural gas, etc. The gas bearing may be a passive or active gas bearing.

[0036] The bushing can be made of a ceramic material or another material that provides sufficient mechanical stiffness and does not affect the magnetic field in the magnetic air gap. The advantage of ceramic materials is that they are suitable both for gas bearings and can be placed in a magnetic air gap where the ceramic material is penetrated by the magnetic field that generates the torque. Typically, electrical insulators or materials with low electrical conductivity such as ceramics, glass ceramics or industrial glass, plastics, composite materials, mineral materials, etc. can be used to avoid excessive eddy current losses caused by the alternating air gap magnetic field.

[0037] In an embodiment, the electric machine is of the slotless type. In other words, the electric stator comprises air gap windings instead of slot windings. In other embodiments, the electric machine is of the slotted type.

[0038] In an embodiment, the cooling body comprises coolant channels for carrying a coolant medium to transfer heat out of the cooling body. The coolant medium is typically a fluid, such as a gas or a liquid.

[0039] According to a second aspect of the invention, which can be realized independently or in combination with one or more other aspects, the cooling body is radially surrounded by a stator flange (which is also called a "stator cooling jacket"), and the stator body and the stator flange are manufactured as a single part or are bonded to each other in terms of material. This allows both the stator body and the cooling body to be thermally coupled and thus the stator body to be cooled via the cooling body.

[0040] Typically, the stator body houses the electric stator. "Material bonding" (also called "substance-to-substance bonding") is typically accomplished by welding or brazing.

[0041] In an embodiment, the stator flange forms at least a part of a wall of the coolant channel. This allows the coolant to effectively cool both the stator body and the cooling body.

[0042] In an embodiment, the stator body comprises a coolant channel, the coolant channel being arranged in a region radially surrounding the electric stator.It may be the case that the stator body comprises an outer stator body radially surrounding an inner stator body, wherein the coolant channel is arranged between the outer stator body and the inner stator body.

[0043] According to a third aspect of the invention, which can be implemented independently or in combination with one or more other aspects, a heat transfer wall is arranged axially adjacent to the electric stator, and an electrically non-conductive and thermally conductive gap tube is attached to the stator radially adjacent to the rotor at a location where the rotor includes permanent magnets, and the heat transfer wall is thermally coupled to the gap tube. This allows cooling of the air gap of the motor via the heat transfer wall and other parts of the stator body.

[0044] The terms “axially adjacent” and “radially adjacent” are understood to mean “adjacent when viewed in the direction of the axis of rotation” and “adjacent when viewed in the radial direction”, respectively.

[0045] In an embodiment, the heat transfer wall is arranged between the electric stator and the cooling body. This may be the case when the electric stator and the cooling body, as seen in the axial direction, are located in different regions along the axis separated by the heat transfer wall.

[0046] In an embodiment, the cooling body is arranged around the electric stator when viewed in radial direction.The heat transfer wall may be arranged to be located on one side of both the electric stator and the cooling body and to form a heat bridge therebetween for transferring heat from the electric stator to the cooling body.

[0047] In an embodiment, instead of a gap tube, there is a gap rod as an elongated element or rod. The gap rod can be arranged in a slot of the slotted motor.

[0048] Thus, the gap tubes or gap rods are arranged at least at the locations where the permanent magnets are present, as viewed in the axial direction along the longitudinal axis of rotation.

[0049] Typically, the can is arranged in the magnetic gap between the stator and the rotor of the electric machine.

[0050] The thermal coupling of the heat transfer wall to the gap tube or gap rod can be accomplished, for example, by force fit (such as press fit) or material fit. In particular, an adhesive, for example, a heat-conducting adhesive, can be used.

[0051] In order to make the gap tubes or gap rods electrically non-conductive and thermally conductive, they can be made of a ceramic material (such as aluminum nitride or silicon carbide or certain grades of silicon nitride) with high thermal conductivity (for example, higher than 20 W / °K / m or 40 W / °K / m or 60 W / °K / m or 100 W / °K / m or 140 W / °K / m).

[0052] In an embodiment, the heat transfer wall comprises radial slots for reducing eddy currents in the heat transfer wall caused by nearby permanent magnets of the rotor. In an embodiment, there are at least 6 or 12 or 18 slots. The slots may be equidistant.

[0053] In an embodiment, the heat transfer wall and the gap tube form part of the airtight spacing between the electric stator and the rotor. This allows to separate the air bearing, which is sensitive to contamination by small particles, from the space inside the stator body, which is usually susceptible to contamination.

[0054] In an embodiment, the motor comprises a heat transfer flange thermally coupled to the gap tube at a distal end opposite to the proximal end of the gap tube, at which a heat transfer wall is arranged. The heat transfer flange may include a coolant channel. This allows heat to be removed from both ends of the gap tube and thereby better cool the gap tube.

[0055] According to a fourth aspect of the invention, which can be realized independently or in combination with one or more of the other aspects, the axial bearing assembly is compressed in the axial direction by an elastic element, wherein the elastic element acts as a disc spring and in turn serves as a wall of the flow path of the compressor driven by the motor, in particular as a wall of the diffuser of a centrifugal compressor. This allows saving space and simplifies the construction of the combination of motor and compressor.

[0056] Typically, a disc spring or Belleville washer (also called a conical disc spring, conical spring washer, leaf spring, Belleville spring or cup spring washer) is generally a conical housing that can be statically or dynamically loaded along its axis (either in a loaded state or in an unloaded state).

[0057] In an embodiment, the disc spring is compressed in the axial direction by a compressor housing part, preferably by a spiral shell of the compressor.This allows to further simplify the construction of the combination of motor and compressor.

[0058] The compressor housing generally comprises a plenum and optionally at least one wall opening into the plenum. The wall may be formed as a single part with the rest of the housing, or as a separate part.

[0059] In an embodiment, the first stator disk and the second stator disk of the axial bearing assembly and the spacing element arranged between the two stator disks are pressed against each other by means of a disk spring.

[0060] In an embodiment, the first stator disc is integrally formed with the bushing. In other words, the first stator disc and the bushing of the axial bearing assembly are manufactured as a single piece or part.

[0061] A thrust bearing or axial bearing generally comprises a rotor disk in the rotor; and, on each side of the rotor disk, an adjacent stator disk on the stator as viewed in the axial direction. The two stator disks are separated by a spacer or a spacing element, so that a well-defined gap is formed between the rotating and fixed parts of the thrust bearing. The stator disk, the spacer and the connecting element together form an axial bearing assembly.

[0062] In an embodiment, the stator disc and the bushing of the axial bearing assembly each comprise an axial facing surface as an axial reference surface, and the two axial reference surfaces are placed against each other.Thereby, they ensure that the rotation axis is perpendicular to the bearing surface of the axial bearing assembly.

[0063] In an embodiment, the stator disk and the bushing, which are placed against each other (if they are not formed in one piece), are pressed against each other by elastic elements, in particular disc springs.

[0064] Other embodiments will be apparent. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] The subject matter of the invention will be explained in detail below with reference to exemplary embodiments illustrated in the accompanying drawings, which show:

[0066] Figure 1a - b is a longitudinal section through a prior art machine with a gas bearing;

[0067] Figure 2 is an embodiment of a motor;

[0068] Figure 3 is an exploded view of a similar embodiment;

[0069] Figure 4 is the stator body, showing the arrangement of the slots; and

[0070] Figure 5 are cross-sectional views of details of further embodiments.

[0071] In principle, identical parts or parts having a similar function are provided with the same reference symbols in the figures. DETAILED DESCRIPTION

[0072] Figure 1a A prior art electric machine with air or gas bearings is schematically shown. Therein, a stator body (not shown) carries an electric stator 3 with coils 31 and a core 32, and further carries an axial bearing section 12 and a radial bearing section 17, wherein a rotor 5 with a shaft 51 and permanent magnets 52 is arranged to rotate. Individual bearing elements 19 constituting the radial bearing section 17 are arranged at opposite ends of the electric machine, with the electric stator 3 located between them. Figure 1b The same elements are shown in a prior art overhang arrangement, wherein the respective bearing elements 19 are arranged at the same end of the electric machine at the same side of the electric stator 3 .

[0073] Here and in other arrangements, a fan 6 or impeller driven by an electric motor operating as a motor is shown as an example of application of the machine. Naturally, any other terminal equipment, especially terminal equipment requiring high-speed drive, can be arranged to be driven by an electric motor.

[0074] Figure 2 An embodiment is schematically shown, wherein the elements already mentioned are present, but in a different arrangement. Furthermore, a stator 1 is shown, comprising a stator body 25 which serves as a housing and supports the electromagnetic components of the stator 1 , namely the coils 31 and the core 32 .

[0075] The parts of the axial bearing segment 12 and the radial bearing segment 17 attached to the stator opposite to the rotor form a stator bearing structure. The stator bearing structure includes the stator-side bearing surfaces of the axial bearing segment 12 and the radial bearing segment 17 and defines the relative positions of these surfaces. The stator bearing structure is designed to be rigid in itself, easy to assemble and align to achieve high precision.

[0076] The axial bearing section 12 or thrust bearing section on a portion of the rotor comprises a generally disc-shaped thrust plate or rotor disc 54 extending outwardly from the outer peripheral surface of the shaft 51 near one end of the rotor 5. The rotor disc 54 has two opposite axially facing surfaces which cooperate with two stator discs 14c, 14d between which the rotor disc 54 is arranged to rotate to form an axial bearing.

[0077] The axial bearing segment 12 on a part of the stator comprises these stator discs 14c, 14d, namely a first stator disc 14c and a second stator disc 14d, which are part of an axial bearing assembly 11. The axial bearing assembly 11 further comprises a spacing element 15, typically a washer, which defines the distance between the axially facing surfaces of the stator discs 14c, 14d facing each other.

[0078] The radial bearing section 17 or journal bearing section on a part of the rotor comprises at least a part of the outer peripheral surface of the shaft 51. This part serves as a rotor bearing surface 53, which cooperates with the bushing 18 to form a radial bearing with a bearing air gap 7. The outer side of the rotor bearing surface 53 may have a radially outwardly protruding section 19a. In this case, the inner side of the bushing 18 may have a constant inner diameter. Alternatively or additionally, the bushing 18 may have a bearing element in the form of a radially inwardly protruding section located at a separate area along the inner side of the bushing 18.

[0079] The radial bearing section 17 on a part of the stator comprises the bushing 18. In this embodiment, the first stator disc 14c and the bushing 18 are formed integrally.

[0080] The stator disks 14c, 14d and the spacer element 15 can be clamped together by means of the disk spring 14b, in particular by applying a force in the axial direction. The force applied by the disk spring 14b can also clamp the first stator disk 14c against the heat sink 71.

[0081] The coil spring 14b also serves as the wall of the diffuser of the compressor driven by the motor. The compressor is a centrifugal compressor having a centrifugal impeller 6, which includes a set of rotating blades (or blades) that gradually increase the energy of the working gas from the inlet 76. Downstream of the impeller 6 in the flow path, the diffuser 77 converts the kinetic energy (high speed) of the gas into pressure by gradually slowing down (diffusing) the gas speed. The gas is discharged from the diffuser into a plenum 78 (also called a volute or vortex).

[0082] The plenum 78 and one wall of the diffuser 77 are formed as part of the compressor housing 14a. The compressor housing or spiral casing 14a is rigidly attached to the cooling body 71 and thereby clamps or compresses the disc spring 14b against the first stator disc 14c.

[0083] At the first and second ends of the bushing 18, it is supported by means of an elastic support 21 (e.g. an O-ring) via the cooling body 71. This suppresses mechanical vibrations that could otherwise occur at the free end of the bushing 18. The elastic support together with the gap between the bushing 18 and the cooling body 71 allow possible deformations of the stator parts to be compensated, for example by thermal expansion. The gap between the bushing 18 and the cooling body 71 can be filled with a thermally conductive filler 23. This allows heat to be dissipated from the bushing 18 to the cooling body 71.

[0084] The bushing 18 is usually completely or mostly located outside the magnetic (air) gap separating the electric stator 3 and the rotor 5 and / or the volume through which the magnetic flux of the drive motor passes. This is usually also the case for the outwardly protruding section 19a and / or the bearing element 19 (if present), as well as the cooperating rotor and stator bearing surfaces of the radial bearing section 17.

[0085] As viewed in the axial or longitudinal direction, the radial bearing section can also be located in the same region as the electric stator. In this case, the heat-conducting filler is arranged between the bushing and the electric stator.

[0086] The position of the bushing 18 relative to the axial bearing assembly 11 is rigidly constrained by only one mechanical link. This link is defined by the bushing 18 and the first stator disc 14c of the stator bearing structure 11, which are formed integrally, or, if not, by axial reference surfaces on one of the bushing 18 and stator discs 14 where the bushing and stator disc are clamped against each other.

[0087] The only other mechanical links between the bushing 18 and the axial bearing assembly 11 (via the cooling body 71) are elastic or resilient, since they extend via the elastic supports 21 and the thermally conductive fillers 23. In this way, the relative position of these parts and in particular the bushing 18 with respect to the stator disk 14 is not overly constrained. Therefore, by precision machining the integral bushing 18 and the first stator disk 14c or the axial reference surface, the alignment accuracy of the axial and radial bearing sections is easily achieved and can be maintained under thermal and mechanical stresses.

[0088] In other words, the axial bearing assembly 11 and the bushing 18 together form a stator bearing structure, and the rotor 5 can be part of one or more kinematic circuits, each of which includes at least one elastic element. In contrast, the axial bearing assembly 11 and the bushing 18 are not part of an overly constrained circuit or arrangement.

[0089] Furthermore, the position of the bushing 18 and therefore the axis of rotation is constrained by the position of the cooling body 71 in a fixed manner with no more than one mechanical linkage, i.e.

[0090] Attachment to the cooling body 71 via the axial bearing assembly 11 .

[0091] Attachment to the cooling body 71 via the bushing 18 .

[0092] The stator flange 28 is formed integrally with the stator body 25. The stator flange 28 is a hollow cylinder which radially at least partially surrounds a cooling body 71, in particular a part of an actively cooled cooling body. Between the cooling body 71 and the stator flange 28, a coolant channel 75 is arranged. Figure 2 and Figure 3The coolant channels 75 are shown as being formed in the cooling body 71 , but they can alternatively or additionally be formed in the stator flange 28 .

[0093] The stator body 25 comprises a heat transfer wall 27 arranged between the cooling body 71 and the electric stator 3. The heat transfer wall 27 extends in a radial direction from the peripheral portion of the stator body 25, where it is coupled to the stator flange 28, to the inner section, where it is coupled to the gap tube 29. The gap tube 29 is a hollow cylinder arranged in the air gap 7a (motor air gap) of the electric machine and is made of a material that is heat-conductive but not electrically conductive. The heat transfer wall 27 is arranged to conduct heat away from the gap tube 29 and thus away from the air gap of the electric machine. The heat transfer wall 27 is thermally coupled to the gap tube 29 at its first end close to the bushing 18.

[0094] The heat transfer wall 27 includes radial gaps 24 to reduce eddy currents generated in the heat transfer wall 27 by the alternating magnetic field of the permanent magnets 52 of the rotor 5. The radial gaps 24 may extend all the way through the heat transfer wall 27, in which case the gaps may be filled with a non-conductive material to keep the heat transfer wall 27 airtight. Alternatively, the radial gaps 24 are left in a thin section of the heat transfer wall 27 to keep the heat transfer wall 27 airtight.

[0095] The main structural components, in particular the compressor housing 14 a , the cooling body 71 and the stator body 25 including the stator flange 28 , are usually made of a metal with good thermal conductivity, in particular aluminum or an aluminum alloy.

[0096] Figure 3 Show Figure 2 An exploded view of the multiple components of the Figure 4 A view showing a separate stator body 25 (with external geometric features similar to those of Figure 2 ), the arrangement of the radial slots 24 is shown.

[0097] Figure 5 A cross-sectional view with details of another embodiment is shown. Therein, the stator body 25 comprises coolant channels 75a. These coolant channels 75a can be formed by a stator body 25 comprising separate parts, the outer stator body 25a radially surrounding the inner stator body 25b. The coolant channels 75a are then formed at the outer side of the inner stator body 25b and / or at the inner side of the outer stator body 25a, wherein these inner and outer sides are in contact. The inner and outer stator bodies are rigidly attached to each other.

[0098] Alternatively, the coolant passage 75 a may be formed by manufacturing the stator body 25 through an additive manufacturing process, forming the coolant passage 75 a when the stator body 25 is produced.

[0099] The spacer tube 29 is shown thermally coupled to the heat transfer flange 27a at a second or distal end.

[0100] Although the heat transfer wall 27 is coupled to the gap tube 29 at the periphery of the gap tube 29, the heat transfer flange 27a may be coupled to the gap tube 29 at the inner side and / or the periphery of the gap tube 29. The heat transfer flange 27a includes a coolant passage 75b. The heat transfer flange 27a is rigidly attached to the stator body 25, or it may be a part of the stator body 25, particularly the inner stator body 25b.

[0101] The thermal coupling of the heat transfer wall 27 and / or the heat transfer flange 27 b to the intermediate tube 29 can be achieved, for example, by means of a heat conductive filler placed between O-rings, by means of a heat conductive glue or by press fitting.

[0102] Where reference is made to coolant passages 75, 75a, 75b, it should be understood that there are other conduits for supplying and removing coolant medium.

Claims

1. A motor, comprising: A stator (1) having a stator body (25) supporting an electric stator (3); and a rotor (5) supported by means of a bearing comprising a radial bearing segment (17) forming a radial gas bearing and an axial bearing segment (12) forming an axial gas bearing, the stator-side parts of these bearing segments being a stator-side radial bearing segment and a stator-side axial bearing segment which are rigidly connected to each other and together form a stator bearing structure, Wherein, the stator-side radial bearing portion is a bushing (18), The invention is characterized in that the bushing (18) is radially surrounded by a cooling body (71), the bushing (18) is connected to the cooling body (71) by an elastic support member, and a heat conductive filler (23) is arranged between the bushing (18) and the cooling body (71); The heat conductive filler (23) is in contact with both the bushing (18) and the cooling body (71) along a section of the axial length of the bushing (18) where the radial gas bearing is present.

2. The motor according to claim 1, wherein: The bushing (18) is radially surrounded by the cooling body (71) and is thermally coupled to the cooling body (71) via the heat conductive filler (23) over at least 20% of the axial length of the bushing (18).

3. The motor according to claim 1 or 2, wherein: The stator bearing structure is mounted to the other part of the stator (1) by the stator-side axial bearing part, and the stator-side axial bearing part is rigidly mounted to the other part, wherein the other part is the stator body itself, or an assembly including the electric stator and a carrier, and the assembly is elastically supported by the stator body.

4. The motor according to claim 3, wherein: The stator bearing structure is mounted to the rest of the stator (1) by an axial bearing assembly (11).

5. The motor according to claim 1 or 2, wherein: The radial bearing section (17) extends in the longitudinal direction of the rotating shaft, and all bearing elements of the radial bearing section (17) and the mating rotor bearing surface are located outside the magnetic gap between the electric stator (3) and the rotor (5).

6. The motor according to claim 1 or 2, wherein: The cooling body (71) comprises a first coolant channel (75) for carrying a coolant medium to transfer heat out of the cooling body (71).

7. The motor according to claim 1, wherein: The bushing (18) is radially surrounded by a cooling body (71), and the cooling body (71) is radially surrounded by a stator flange (28), and the stator body (25) and the stator flange (28) are manufactured as a single part or are materially bonded to one another.

8. The motor according to claim 7, wherein: The cooling body (71) comprises a first coolant channel (75) for carrying a coolant medium for transferring heat out of the cooling body (71), and wherein the stator flange (28) forms at least a part of a wall of the first coolant channel (75).

9. The electric machine according to claim 7 or 8, wherein: The stator body (25) comprises a second coolant channel (75a) which is arranged in a region radially surrounding the electric stator (3).

10. The electric machine according to claim 9, wherein: The stator body (25) comprises an outer stator body (25a) radially surrounding an inner stator body (25b), and wherein the second coolant passage is arranged between the outer stator body (25a) and the inner stator body (25b).

11. The electric machine according to claim 1, wherein: The stator (1) comprises a heat transfer wall (27) which is arranged axially adjacent to the electric stator (3), and an electrically non-conductive and thermally conductive gap tube (29) is attached to the stator (1) radially adjacent to the rotor (5) at a location where the rotor (5) comprises permanent magnets (52), and the heat transfer wall (27) is thermally coupled to the gap tube (29).

12. The electric machine according to claim 11, wherein: The heat transfer wall (27) is arranged between the electric stator (3) and the cooling body (71).

13. The electric machine according to claim 11 or 12, wherein: The heat transfer wall (27) comprises radial slots (24) for reducing eddy currents in the heat transfer wall (27) caused by nearby permanent magnets (52) of the rotor (5).

14. The electric machine according to claim 11 or 12, wherein: The heat transfer wall (27) and the gap tube (29) form part of the gas-tight interval between the electric stator (3) and the rotor (5).

15. The electric machine according to claim 11 or 12, comprising a heat transfer flange (27b) thermally coupled to the gap tube (29) at a distal end opposite to a proximal end of the gap tube (29), at which the heat transfer wall (27) is arranged.

16. The electric machine according to claim 15, wherein: The heat transfer flange (27b) includes a third coolant channel (75b).

17. The electric machine according to claim 1, wherein: The stator bearing structure is mounted to the other part of the stator (1) by the stator-side axial bearing part, the stator-side axial bearing part is rigidly mounted to the other part, wherein the other part is the stator body itself, or an assembly including the electric stator and a carrier, the assembly being elastically supported by the stator body; The axial bearing assembly (11) is compressed in the axial direction by an elastic element, wherein the elastic element acts both as a disc spring (14b) and as a wall of a flow path of a compressor driven by the motor.

18. The electric machine according to claim 17, wherein: The stator bearing structure is mounted to the rest of the stator (1) by an axial bearing assembly (11).

19. The electric machine according to claim 17, wherein: The disc spring (14b) is compressed in the axial direction by a compressor housing (14a) of the compressor.

20. The electric machine according to any one of claims 17 to 19, wherein: The first stator disc (14c) and the second stator disc (14d) of the axial bearing assembly (11) and a spacing element (15) arranged between the two stator discs (14c, 14d) are pressed against each other by the disc spring (14b).

21. The electric machine according to claim 20, wherein: The first stator disc (14c) is formed integrally with the bushing (18).

22. The electric machine according to claim 1, wherein The bushing (18) is radially surrounded by the cooling body (71) and is thermally coupled to the cooling body (71) via the heat conductive filler (23) over at least 40% of the axial length of the bushing (18).

23. The electric machine according to claim 1, wherein The bushing (18) is radially surrounded by the cooling body (71) and is thermally coupled to the cooling body (71) via the heat conductive filler (23) over at least 60% of the axial length of the bushing (18).

24. The electric machine according to claim 1, wherein The bushing (18) is radially surrounded by the cooling body (71) and is thermally coupled to the cooling body (71) via the heat-conducting filler (23) over at least 80% of the axial length of the bushing (18).

25. The electric machine according to claim 17, wherein: The elastic element is used as a wall of a diffuser of a centrifugal compressor.

26. The electric machine according to claim 19, wherein The disc spring (14b) is compressed in the axial direction by a spiral housing of the compressor.

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