DE102021105732A1 - Gas-bearing micro-turbo machine - Google Patents

Abstract

The micro-turbo machine with a rotor (1), at least one impeller (4) and a thrust bearing disc (5) is characterized in that the overall rotor consists of several partial shaft elements, which comprise the impeller (1), the thrust bearing disc (5) and the E-rotor (1) and is assembled by means of a concentric self-centering connection, the entire rotor having gas/air bearings and in a housing which is axially divided into several housing parts and the housing parts containing the bearing points by means of concentric self-centering connections (9), (10). Figure 1 is suggested as a drawing for the summary.

Description

The invention relates to a micro-turbomachine with a shaft constructed from a plurality of partial shaft elements, the partial shaft elements being connected to one another in a self-centering manner.

The self-centering function takes place by means of conical multi-wedge profiles. The conical multi-spline profiles are pronounced over the entire circumference or in segments on the front connecting surface of the individual partial shaft elements.

A partial shaft element contains the impeller of the turbomachine. At least one other shaft element is designed as a thrust bearing disk for axial storage. A third partial shaft element can contain an e-rotor as a motor or generator, or an additional impeller. Additional shaft elements can be designed for additional impellers or other functional elements, such as radial or axial bearings.

The invention relates to a micro-turbomachine that functions as a compressor and is driven by an electric motor seated on a common overall rotor composed of several partial shaft elements. A drive is also possible via a turbine wheel seated on the entire rotor.

The drive can only be provided by the electric motor or only via the turbine impeller or together by the electric motor and turbine.

The microturbomachine can also function as a turbine, with a generator rotor acting as a brake on the assembled overall rotor. A compressor impeller or a combination of compressor impeller and generator rotor can also be used as a brake.

The invention relates to a micro-turbo machine whose overall rotor composed of several shaft elements is mounted in two or more radial gas bearings. The radial gas bearings can be designed as gas-dynamic bearings or as static gas bearings or a gas-dynamic - gas-static combination.

The shaft is supported axially by means of a gas bearing, which is designed to be gas-dynamic, gas-static or a combination of gas-dynamic and gas-static.

The axial bearing can also be implemented as an active or passive magnetic bearing.

The invention relates to a micro-turbomachine whose housing parts, which contain bearing points and any housing parts lying in between, are connected to one another with self-centering, conical multi-spline profiles on the face side. The conical multi-wedge profiles are pronounced over the entire circumference or in segments on the front connecting surfaces of the individual housing parts and can contain a double wedge profile and a double wedge gap profile in the counterpart.

State of the art

1. Micro-turbomachines with dynamic, static or combined dynamic/static gas or air bearings are used for very high-speed turbomachines, e.g. In the case of fuel cell systems, these are usually film bearings or so-called herringbone bearings (groove bearings).

The latter place high demands on the manufacture and precision of the components, since these bearings work with small bearing gaps. However, this makes it possible for the flow-guiding components such as impellers to work with small gaps. As a result, microturbines achieve very good volumetric efficiencies.

2. High-speed microturbo compressors with herringbone bearings are known, in which the rotor consists of a shaft or two materially connected shaft elements and is mounted radially in two dynamic gas bearings. The components such as the impeller and other parts are heat shrunk onto the shaft. Due to the high speeds and existing shrinkage stresses, the components are exposed to very high stresses. Deformations and high stresses during operation can destabilize the bearing or lead to the impeller failing in terms of strength. Furthermore, the integral connection of two shaft elements places further increased demands on production in order to produce a connection that is flawless in terms of strength.

Assembly is complex, disassembly is even more difficult, and the manufacture of the complete rotor, including the bearing, requires a great deal of effort. Rotors or turbo machines for very high speeds must also be very well balanced so that harmful imbalance forces are avoided or reduced as far as possible. In the case of very high-speed turbomachines, it is recommended to balance the entire rotor, i.e. the shaft together with the components or masses on the shaft, such as impellers, thrust bearing disc and e-rotor. This requires an assembly and subsequent disassembly of the entire rotor unit. Shrinking an impeller onto the shaft thus makes it more difficult to reproduce the state of balance during subsequent final assembly.

Furthermore, very high-speed microturbomachines are designed to be as short as possible and with only two radial bearing points with regard to rotor dynamics and to avoid passing through the first bending-critical speed or natural frequency of the rotor. This severely limits the constructive possibilities for the design of such a rotor and thereby also limits certain performance-related designs to lower speeds.

Extremely high-speed gas-bearing turbomachines with a central housing part are often designed in such a way that, if possible, both radial bearings are integrated into this housing part in order to ensure good alignment of the bearing bores. This further restricts the structural designs and mounting options.

• • EP-B1 3 008 344 : Turbo-Expander/Kompressor-Welle mit Hirth-Verzahnung,
• • DE-C1 41 28 673 : Strömungsmaschine mit zentrierenden Stirnverzahnungen zwischen Rotorteilen und Laufrädern,
• • DE-A1 10 2010 040 288: Rotor mit Hirth-Verzahnung zwischen Welle und Laufrad,
• • EP-B1 2 872 744 : Radialkompressor-Rotor mit Hirth-Verzahnung,
• • DE-B 11 99 545 : Naben-Wellen-Zentrierung (insb. Für Turbomaschinen) durch Hirth-Verzahnung,
• • DE-C2 30 21 318 : Pumpenwelle mit selbstzentrierender Stirnverzahnung für Laufrad und Spurscheibe,
• • EP-A1 3 579 390 Turbo-Kompressor mit dynamischem bzw. statischem Gaslager,
• • EP-A1 775 830 Turbo-Kompressor mit dynamischen Gaslagern und Spiralrillen,
• • US-B2 88 27 634 : Turbo-Kompressor mit Folien-Gaslager.

3. The state of the art is also mentioned:

• • EP-B1 3 008 344 : turbo expander/compressor shaft with Hirth gearing,
• • DE-C1 41 28 673 : turbomachine with centering spur gears between rotor parts and impellers,
• • DE-A1 10 2010 040 288: Rotor with Hirth serration between shaft and impeller,
• • EP-B1 2 872 744 : centrifugal compressor rotor with Hirth gearing,
• • DE-B 11 99 545 : hub-shaft centering (esp. for turbo machines) by Hirth gearing,
• • DE-C2 30 21 318 : Pump shaft with self-centering spur gearing for impeller and track disc,
• • EP-A1 3 579 390 Turbo compressor with dynamic or static gas bearing,
• • EP-A1 775 830 Turbo compressor with dynamic gas bearings and spiral grooves,
• • US-B2 88 27 634 : Turbo compressor with foil gas bearing.

Object and solution of the invention

Object of the invention: The disadvantages of the prior art mentioned above are to be avoided.

In a micro-turbomachine of the type mentioned at the outset, this object is achieved according to the invention in that the shaft is divided into at least three or more shaft elements which are each assembled at the end by a conical self-centering connection. This multiple-split overall rotor contains at least a first part-shaft element, which is designed as an impeller, a second shaft element with a second impeller or a thrust bearing disk, and a third shaft element contains an E-rotor, with the assembled overall rotor being divided into two or more than two radial gas or .Air bearings.

Housing parts that contain radial bearing points are assembled with other housing parts via end face conical self-centering connections.

Advantages of the Invention

• Großen Einfluss auf die Rotordynamik und eine stabile Lagerung des Gesamtrotors für sehr hohe Drehzahlen haben hier die Teilwellenelemente wie Laufrad (4), Spurlagerscheibe (5) als auch der E-Rotor sowie deren Anordnung und die Anordnung der Radiallager innerhalb des Gesamtrotors sowie andere Elemente.

Among other things, the following advantages are achieved:

• The partial shaft elements such as impeller (4), thrust bearing disc (5) and the electric rotor as well as their arrangement and the arrangement of the radial bearings within the overall rotor as well as other elements have a great influence on the rotor dynamics and a stable bearing of the entire rotor for very high speeds.

A conical self-centering connection of the individual partial shaft elements is immanently important here in order to avoid displacements and deformations in connection with high operating speeds and temperatures and to achieve reliable reproducibility of the balancing state. A planar multi-spline connection (7) analogous to a Hirth toothing ensures maximum flank and self-centering due to the conical inward spline.

The e-rotor partial shaft element (1) with two radial gas or air bearings (2) can thus be manufactured separately and precisely and then connected to other partial shaft elements to form an overall rotor. In addition, assembly is very simple, since the individual shaft elements can be connected with low axial forces. The positional fixation is ensured at all times by the conical keyways, so that assembly and disassembly do not affect the concentricity with the gas or air bearings 2 .

The merging of, in particular, gas-dynamic herringbone bearings in connection with a planar multi-spline connection allows for a simple structure and precise manufacture of the entire rotor, the reliable reproducibility of the balancing quality required for functionality at very high speeds and is therefore very well suited for the production of large quantities. A double-tooth profile or wedge on one end face and a double-tooth gap profile on the counterpart can increase the reliability for the reproducibility of the balance state for series production for assembly and disassembly.

The most important thing is the self-centering, conical multiple spline profile for the direct connection of the individual partial shaft elements, especially for an air-bearing e-rotor with the partial shaft elements impeller and thrust bearing or additional bearing points. This ensures easy assembly and reproduction of the state of balance, immediate high acceleration or deceleration by an electric motor/generator or by means of a turbine in combination with the particularly gas-dynamic bearing of the entire rotor and high-speed operation without the risk of an impeller bore or the like widening and the associated problems risks.

The overall rotor, which is composed of several hollow and/or solid shaft elements by means of a self-centering conical splined connection, opens up more freedom in the rotordynamic design of the overall rotor, among other things because the partial shaft elements can be made of a wide variety of materials, such as steel, titanium or aluminum alloys, CFRP or plastic and much more . For example, not only the partial shaft element of an impeller, but also the partial shaft element of the thrust bearing disc can be made of other materials, in particular the thrust bearing disc made of high-strength plastic or CFRP, which allows larger diameters, e.g. for an axial gas or air bearing or even higher speeds be able.

Furthermore, this also enables the possibility of additional radial bearing points in a simple manner, in particular with a gas-dynamic bearing for very high-speed applications.

Due to the above-mentioned advantages of using different materials for the shaft elements, in particular for the impeller shaft element and for the thrust bearing shaft element and the possibility of additional radial bearing points, for the rotordynamic design of the entire rotor, operation of the microturbomachine in the subcritical range, i.e. below the first natural bending frequency, can be significantly improved be realized more easily. This applies in particular to the realization of greater performance at comparably high speeds, which is otherwise only found with lower performance.

Furthermore, more design freedom is possible due to the subdivision into several partial shaft elements and the ability to combine a wide variety of diameters of these shaft elements while still being able to assemble them.

The use of conical, self-centering multi-wedge connections for housing components on the face side simplifies manufacture and improves the alignment of the bearing bores with one another. The segmented design of the multi-wedge connection (9) or the design with a double wedge profile (10) combined with a double gap profile on the counterpart also simplify reliable assembly and disassembly, especially in series production.

In developing the micro-turbomachine according to the invention, the inventors have overcome the following technical difficulties in a way that is not obvious.

A possibility was sought to subdivide an overall rotor into several partial shaft elements that can be easily connected or separated again and an E-rotor (1) as well as the sampling (grooving) for gas-dynamic radial bearings, at least one impeller (4) and a thrust bearing disc ( 5) include.

In this way, a simplification of a high-precision production necessary for gas-dynamic bearings should be achieved. At the same time, a reliable centering assembly / disassembly with reproducibility of the balancing condition and the reliable connection of the individual partial shaft elements should be guaranteed even at high speeds and temperature differences.

Furthermore, the possibility of greater design freedom with regard to the rotordynamic design and the use of different materials should be created.

Another task was to produce the housing parts containing the bearing points / bores as simply as possible and at the same time to achieve very good alignment of the bearing points in the housing components to be connected in order to ensure or improve the functionality of the gas bearing.

It is known that Hirth couplings for large rotors can meet these requirements. However, the requirements there are not as high, since the rotors are usually filled with liquid lubricated bearings are mounted and larger tolerances are allowed here.

It should also be emphasized here, among other things, that self-centering conical multiple spline connections analogous to Hirth toothing are usually only used for shaft diameters of 50 mm and above. However, shaft diameters of very high-speed microturbo machines often have shaft diameters of less than 50 mm. With today's modern production possibilities, the production of such conical multi-wedge connections is possible without any problems and enables an overall rotor divided several times in the longitudinal direction, in particular for very high-speed microturbomachines designed with dynamic gas bearings.

So far, these clutches have not been used for the micro-turbo machine sector.

The use of this type of connection for housing components to ensure the necessary good alignment of bearing points is also not known in the field of micro-turbomachines.

A high-precision, concentric, self-centering connection with the shaft elements for a gas-dynamic bearing could be created by means of a conical multi-wedge profile on the planar shaft ends to be connected. At the same time, a very good alignment of the bearing bores could be achieved by using this connection on the housing components.

In addition, the solution described above opens up a whole range of new possibilities in terms of construction and design for gas-bearing micro-turbomachines.

Advantageous developments of the invention are specified in the subclaims.

• - dass die konzentrische selbstzentrierende Verbindung als eine planare Vielkeilprofilverbindung (7) ausgebildet ist zur Verbindung von mindestens drei Teilwellenelementen
• - dass die planare Vielkeilverbindungen zum Zusammenbau der Teilwellenelemente auf einer Stirnseite einen Doppelkeil beinhaltet und das entsprechende Gegenstück eines zweiten Teilwellenelementes eine passende Doppellücke aufweist
• - dass der aus Teilwellenelementen zusammengesetzte Gesamtrotor in zwei oder mehr radialen Gas/Luftlagern gelagert wird
• - dass die radialen dynamischen Gas/Luftlager (2) als Folienlager oder Fischgräten-Lager ausgebildet sind
• - dass die radialen Gas/Luftlager (2) als statisches oder als Kombination statischer / dynamischer Gaslager ausgebildet sind
• - dass die Axiallagerung ebenfalls als dynamisches Gaslager ausgebildet ist
• - dass die Axiallagerung als statisches oder als Kombination statischer / dynamischer Gaslager ausgebildet ist
• - dass die Axiallagerung als aktives Magnetlager ausgebildet ist
• - dass die Axiallagerung als passives Magnetlager ausgebildet ist
• - dass die Teilwellenelemente aus unterschiedlichen Materialien ausgeführt sind
• - dass ein Wellenelement einen E-Rotor (Motor oder Generator) beinhaltet und sich der E-Rotor auf einem Wellenelement aus Stahl, vorzugsweise aus ferromagnetischem Stahl ausgeführt ist
• - dass mindestens ein Teilwellenelement ein Laufrad beinhaltet
• - dass das laufradbeinhaltende Wellenelement aus einer hochfesten Aluminium- oder Titanlegierung besteht
• - dass das laufradbeinhaltende Wellenelement aus einem Kunststoff besteht
• - dass das laufradbeinhaltende Wellenelement aus CFK besteht
• - dass das laufradbeinhaltende Wellenelement aus einer Materialmischung besteht, beispielsweise aus einer tragenden Struktur eines hochfesten Werkstoffes welche mit Kunststoff umspritzt oder 3D gedruckt wird
• - dass mindestens ein Teilwellenelement eine Spurlagerscheibe beinhaltet
• - dass das Teilwellenelement, welches eine Spurlagerscheibe beinhaltet, aus einer hochfesten metallischen Legierung besteht
• - dass das Teilwellenelement, welches eine Spurlagerscheibe beinhaltet, aus einem Kunststoff besteht
• - dass das Teilwellenelement, welches eine Spurlagerscheibe beinhaltet, aus CFK besteht
• - dass Gehäusebauteile, die Lagerstellen bzw. entsprechende Bohrungen für die Radiallager beinhalten, stirnseitig mit einer konzentrisch selbstzentrierenden planaren Vielkeilprofilverbindung ausgeführt sind
• - dass die planaren Vielkeilverbindungen zum Gehäusezusammenbau segmentweise ausgeführt werden
• - dass die planare Vielkeilverbindungen auf einer Stirnseite einen Doppelkeil beinhaltet und das entsprechende Gegenstück eines zweiten Gehäusebauteils eine passende Doppellücke aufweist
• - dass die planaren Vielkeilverbindungen zum Gehäusezusammenbau segmentweise ausgeführt werden und ein Segment einen Doppelkeil beinhaltet und das entsprechende Gegenstück eines zugepaarten Gehäusebauteils ein Segment mit einer passenden Doppellücke aufweist

So it is suggested

• - That the concentric self-centering connection is designed as a planar multi-spline connection (7) for connecting at least three partial shaft elements
• - That the planar splined connection for assembling the partial shaft elements includes a double wedge on one end face and the corresponding counterpart of a second partial shaft element has a matching double gap
• - that the entire rotor composed of partial shaft elements is mounted in two or more radial gas/air bearings
• - That the radial dynamic gas / air bearings (2) are designed as foil bearings or herringbone bearings
• - That the radial gas / air bearings (2) are designed as a static or as a combination of static / dynamic gas bearing
• - That the axial bearing is also designed as a dynamic gas bearing
• - That the axial bearing is designed as a static gas bearing or as a combination of static/dynamic gas bearings
• - That the axial bearing is designed as an active magnetic bearing
• - That the axial bearing is designed as a passive magnetic bearing
• - That the partial wave elements are made of different materials
• - That a shaft element includes an E-rotor (motor or generator) and the E-rotor is carried out on a shaft element made of steel, preferably ferromagnetic steel
• - That at least one partial wave element includes an impeller
• - that the shaft element containing the impeller consists of a high-strength aluminum or titanium alloy
• - That the shaft element containing the impeller consists of a plastic
• - that the shaft element containing the impeller is made of CFRP
• - That the shaft element containing the impeller consists of a material mixture, for example a supporting structure of a high-strength material which is overmoulded with plastic or 3D printed
• - That at least one partial wave element includes a thrust bearing disc
• - That the partial shaft element, which includes a thrust bearing disc, consists of a high-strength metallic alloy
• - That the partial shaft element, which includes a thrust bearing disc, consists of a plastic
• - That the partial shaft element, which includes a thrust bearing disc, is made of CFRP
• - That housing components, which contain bearing points or corresponding bores for the radial bearings, are designed on the front side with a concentric self-centering planar splined connection
• - that the planar multi-wedge connections for assembling the housing are carried out in segments
• - That the planar multi-wedge connection includes a double wedge on one end face and the corresponding counterpart of a second housing component has a matching double gap
• - That the planar splined connections to the housing assembly are carried out segment by segment and one segment contains a double key and the corresponding counterpart of a mating housing component has a segment with a matching double gap

example

An exemplary embodiment of the invention is described in more detail below with reference to drawings. In all drawings, the same reference numbers have the same meaning and are therefore only explained once where appropriate.

• 1 eine perspektivische Darstellung eines erfindungsgemäßen Ausführungsbeispiels eines Rotorsystems, bestehend aus Motorrotor mit Groove-Luftlagern (Fischgrätenbemusterung), welches über ein planares Vielkeilprofil mit Laufrad und Spurlager verbunden ist,
• 2 eine perspektivische Darstellung des erfindungsgemäßen Motorrotors mit Groove-Luftlagern (Fischgrätenbemusterung) und planaren Vielkeilprofilen links und rechts,
• 3 den Aufbau des Vielkeilprofils stark vergrößert und
• 4 Gehäusebauteil mit segmentweise angeordneten Vielkeilprofilen sowie mit einem Doppelkeil

Show it

• 1 a perspective view of an exemplary embodiment of a rotor system according to the invention, consisting of a motor rotor with groove air bearings (herringbone pattern), which is connected to the impeller and thrust bearing via a planar multi-spline profile,
• 2 a perspective view of the motor rotor according to the invention with groove air bearings (herringbone pattern) and planar multi-spline profiles left and right,
• 3 the structure of the multi-wedge profile greatly enlarged and
• 4 Housing component with multi-wedge profiles arranged in segments and with a double wedge

Structure of the micro turbomachine

In 1 is a rotor system according to the invention with the motor rotor 1 with groove air bearings 2, the planar multi-wedge profiles 3 for the connections of the impeller 4 and the thrust bearing 5 is shown.

2 shows the drive part, namely the motor rotor 1 with the groove air bearings 2 and the planar multi-spline profiles 3.

In 3 the multi-wedge profile 3 is shown greatly enlarged.

4 shows a housing component which contains the stator of the electric motor and is provided with multiple spline profiles 9 arranged in segments on the end face. A double wedge 10 is also shown here.

Manufacture of the micro-turbomachine

• Schritt 1: Das Antriebsteil Motorrotor 1 mit Groove-Luftlagern 2 und planaren Vielkeilprofilen 3 an den Enden wird separat hergestellt und kann auch separat erprobt werden.
• Schritt 2: Bauteile wie Laufrad 4 und Spurlager 5 werden an den Motorrotor angedockt und bilden so ein variables Rotorsystem.
• Schritt 3: Die Bauteile Laufrad 4 und Spurlager 5 werden jeweils über eine Schraube axial mit dem Motorrotor 1 verspannt und zentrieren sich selbsttätig über die Flanken 8 des Keilprofils.
• Schritt 4: Nun kann der Gesamtrotor als eine Einheit ausgewuchtet werden. Nach dem Auswuchten kann der Gesamtrotor für die anschließende Montage des kompletten Turbokompressors wieder demontiert und bei der Montage wieder in einzelnen Schritten zusammen mit den Gehäusebauteilen montiert werden. Dabei wird zuerst der Motorrotor 1 in das Gehäusebauteil (4) eingeführt. Anschließend kann das Laufrad 4 mit dem Motorrotor 1 axial über die selbstzentrierende planare Keilverbindung verschraubt werden. Danach ist die Montage des hinteren Lagerflansches, welcher ebenfalls eine planare und segmentweise angeordnete Keilprofile enthält, mit dem den Motorstator beinhalteten Gehäusebauteil (4) verbunden werden. Dabei kann auf Grund der Doppelkeillücke, welche das Gegenstück des Doppelkeils (10) darstellt, der Lagerflansch (hier nicht dargestellt) nur in einer definierten Position mit dem Motorstatorgehäuse verbunden werden. Danach kann dann die Spurlagerscheibe mit dem Motorrotor zum Gesamtrotor verbunden werden.

The production of the micro-turbomachine according to the invention is explained in detail below:

• Step 1: The motor rotor drive part 1 with groove air bearings 2 and planar multi-spline profiles 3 at the ends is manufactured separately and can also be tested separately.
• Step 2: Components such as the impeller 4 and thrust bearing 5 are docked onto the motor rotor and thus form a variable rotor system.
• Step 3: The components impeller 4 and thrust bearing 5 are each clamped axially to the motor rotor 1 via a screw and center themselves automatically via the flanks 8 of the wedge profile.
• Step 4: Now the entire rotor can be balanced as a unit. After balancing, the entire rotor can be dismantled again for the subsequent assembly of the complete turbo compressor and reassembled in individual steps together with the housing components during assembly. First the motor rotor 1 is inserted into the housing component ( 4 ) introduced. The impeller 4 can then be screwed axially to the motor rotor 1 via the self-centering planar spline connection. Then the assembly of the rear bearing flange, which also contains a planar wedge profile arranged in segments, with the housing component containing the motor stator ( 4 ) get connected. Due to the double wedge gap, which represents the counterpart of the double wedge (10), the bearing flange (not shown here) can only be connected to the motor stator housing in a defined position. Then the thrust bearing disc can be connected to the motor rotor to form the overall rotor.

Reference List

1

motor rotor

2

Groove Air Bearings

3

planar splined profiles

4

Wheel

5

track bearing

6

stub shaft

7

conical wedge profile

8th

flanks of the wedge profile

9

Planar conical multi-spline profiles arranged in segments

10

double wedge profile

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was 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.

Patent Literature Cited

• EP 3008344 B1 [0017]
• DE 4128673 C1 [0017]
• EP 2872744 B1 [0017]
• DE 1199545 B [0017]
• DE 3021318 C2 [0017]
• EP 3579390 A1 [0017]
• EP 775830 A1 [0017]
• US 8827634 B2 [0017]

Claims (35)

Micro-turbo machine, consisting of an overall rotor composed of several partial shaft elements, characterized in that at least one partial shaft element is an impeller (4), a second partial shaft element is a thrust bearing (5) and a third partial shaft element is an electric rotor (1) and/or another Impeller includes, the partial shaft elements connected to each other with a concentric self-centering connection and that the assembled total rotor in gas - or air bearings (2) is stored. micro-turbomachine claim 1 , characterized in that the concentric self-centering connection is designed as a planar splined connection (7). micro-turbomachine claim 2 , characterized in that the planar multi-spline profile connection is pronounced over the entire circumference on the front connecting surface of the individual partial shaft elements. micro-turbomachine claim 2 , characterized in that the planar multi-spline profile connection is formed in segments on the end-side connection surface of the individual partial shaft elements. Micro turbomachine according to the above claims 2 until 4 , characterized in that the planar splined connection contains a double wedge and the counterpart a corresponding double gap micro-turbomachine claim 1 , characterized in that the gas / air bearings (2) are designed as dynamic gas / air bearings. micro-turbomachine claim 6 , characterized in that the radial dynamic gas/air bearings are designed as foil bearings or herringbone bearings, in particular groove bearings. micro-turbomachine claim 1 , characterized in that the gas / air bearings are designed as static gas / air bearings. micro-turbomachine claim 1 , characterized in that the gas / air bearings are designed as a combination of static and dynamic gas / air bearings. Micro turbomachine according to the above claims 1 and 6 - 9 , characterized in that the radial bearings are designed as gas / air bearings and the axial bearing as a magnetic bearing. micro-turbomachine claim 10 , characterized in that the axial bearing is designed as an active magnetic bearing. micro-turbomachine claim 10 , characterized in that the axial bearing is designed as a passive magnetic bearing. micro-turbomachine claim 1 and/or the other aforementioned claims, characterized in that the partial wave elements are made of different materials. micro-turbomachine Claim 13 , characterized in that a part-shaft element includes an E-rotor (motor or generator) and the E-rotor is located on a part-shaft element (1) made of steel, preferably of ferromagnetic steel. micro-turbomachine Claim 13 , characterized in that at least one partial shaft element includes an impeller (4). micro-turbomachine claim 15 , characterized in that the impeller-containing partial shaft element (4) consists of a high-strength aluminum or titanium alloy. micro-turbomachine claim 15 , characterized in that the part-shaft element (4) containing the impeller consists of a plastic. micro-turbomachine claim 15 , characterized in that the part-shaft element (4) containing the impeller consists of CFRP. micro-turbomachine claim 15 , characterized in that the impeller-containing partial shaft element (4) consists of a material mixture, for example a supporting structure of a high-strength material which is overmoulded with plastic or 3D printed. micro-turbomachine claim 1 , characterized in that at least one partial shaft element includes a thrust bearing disc (5). micro-turbomachine claim 20 , characterized in that the partial shaft element, which includes a thrust bearing disc (5), consists of a high-strength metallic alloy. micro-turbomachine claim 20 , characterized in that the partial shaft element, which includes a thrust bearing disc (5), consists of a plastic. micro-turbomachine claim 20 , characterized in that the partial shaft element, which includes a thrust bearing disc (5), consists of CFRP. micro-turbomachine claim 1 , 20 until 23 , characterized in that at least one partial shaft element contains a thrust bearing disc (5) which acts on two sides. Micro-turbomachine according to the preceding claims, characterized in that at least one rear side of an impeller is designed as a counter-surface for the axial bearing. micro-turbomachine claim 1 , characterized in that housing components ( 4 ), which contain bearing points or corresponding bores for the radial bearings, are designed on the face side with a concentric self-centering planar splined connection. micro-turbomachine Claim 26 , characterized in that the planar splined connections for housing assembly are frontal on the full circumference. micro-turbomachine Claim 26 , characterized in that the planar splined connections for assembling the housing are carried out in segments (9) over the end circumference. micro-turbomachine Claim 26 , 27 and 28 , characterized in that the planar multi-wedge connections contain a double wedge (10) on one end face and the corresponding counterpart of a second housing component has a matching double gap. micro-turbomachine claim 1 , for mobile applications. micro-turbomachine claim 1 , for stationary applications. micro-turbomachine claim 1 , 30 and 31 , characterized in that at least one impeller is designed as a compressor impeller (1) and the electric rotor is designed as an electric motor. micro-turbomachine claim 1 , 30 and 31 , characterized in that at least one impeller is designed as a turbine impeller and the electric rotor as an electric generator. micro-turbomachine claim 1 , 30 and 31 , characterized in that an impeller is designed as a compressor impeller and a second as a turbine impeller and the electric rotor as an electric motor. micro-turbomachine claim 1 , 30 and 31 , characterized in that a partial shaft segment is designed as a compressor impeller and a second partial shaft segment is designed as a turbine impeller instead of as an electric rotor.

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