DE102020210694A1 - Electrical machine and method for its manufacture - Google Patents

Abstract

The invention relates, among other things, to an electrical machine with a stator, a rotor shaft (10) and a machine element (30) placed on the rotor shaft (10). According to the invention, at least in the area between the rotor shaft (10) and the machine element (30) a metal coating (20) is applied to the rotor shaft (10), the machine element (30) or to both of the parts mentioned, which forms an intermediate metal layer between the rotor shaft (10) and the machine element (30) and prevents overload-related relative rotation between the machine element (30) and the rotor shaft (10), the material of the metal coating (20) differing both from the material of the rotor shaft (10) and from the material of the machine element (30).

Description

The invention relates to electrical machines with a stator, a rotor shaft and a machine element placed on the rotor shaft.

Such machines are used, for example, as drive motors in railway vehicles. In the case of drive motors in railroad vehicles, there is the problem that high torque peaks, so-called short-circuit torques, can occur if the drive motors are controlled by converters in the event of semiconductor faults. These load peaks are undesirable for the drive train of the railroad vehicles.

The invention is based on the object of specifying an electrical machine in which the described problem of load peaks is reduced.

According to the invention, this object is achieved by an electrical machine having the features according to patent claim 1 . Advantageous configurations of the electrical machine are specified in the dependent claims.

According to the invention, it is provided that at least in the area between the rotor shaft and the machine element, a metal coating is applied to the rotor shaft, the machine element or to both of the parts mentioned, which forms an intermediate metal layer between the rotor shaft and the machine element and prevents overload-related relative rotation between the machine element and of the rotor shaft, the material of the metal coating differing both from the material of the rotor shaft and from the material of the machine element.

A major advantage of the electric machine according to the invention is that the metal coating helps avoid the occurrence of high torque peaks by allowing overload-related relative rotation between the machine element and the rotor shaft, i.e. slipping, due to its positioning between the machine element and the rotor shaft. At the same time, the risk of cold welding or seizure between the machine element and the rotor shaft is reduced by the metal coating, since the metal coating structurally separates the machine element and rotor shaft.

Another significant advantage of the electrical machine according to the invention or the metal intermediate layer provided according to the invention is that it does not form a separate or additional component that would have to be installed, but is installed together with the machine element or the rotor shaft without additional effort due to the design as a metal coating .

Yet another essential advantage of the electrical machine according to the invention or the intermediate metal layer provided according to the invention is that the intermediate metal layer can be applied using a simple coating process. It is also possible to specifically adjust the surface quality of the metal intermediate layer, the layer thickness of the metal intermediate layer and/or the diameter (inner diameter or outer diameter) of the coated component (rotor shaft or machine element) using standard processes (e.g. turning, polishing, etc.) so that very tight tolerances can be achieved with little effort. For example, much tighter tolerances can be achieved than would be possible if an intermediate sleeve were used as a separate component between the rotor shaft and the machine element. By adhering to particularly tight tolerances, the behavior of the overload protection can in turn be adjusted in a targeted manner, for example with regard to the torque at which the metal intermediate layer should allow a relative rotation between the rotor shaft and the machine element.

Yet another significant advantage of the electrical machine according to the invention or the intermediate metal layer provided according to the invention is that the thickness of the separating layer between the rotor shaft and the machine element can be selected to be much smaller than the wall thickness of an intermediate sleeve if one is used as a separate component between the rotor shaft and the machine element would use; because an intermediate sleeve would normally have to have a wall thickness in the millimeter range with regard to production, handling and assembly, whereas the metal intermediate layer according to the invention can manage with wall thicknesses of less than 0.1 millimeters depending on the machine dimensions. The metal coating according to the invention thus saves space and weight in comparison with a separate intermediate sleeve.

The metal coating can be applied in any way, for example by flame spraying, thermal spraying processes for metallic materials or build-up welding. However, with a view to minimal heat input into the component to be coated, ie rotor shaft and/or machine element, it is considered particularly advantageous if the metal coating is a sprayed-on cold gas spray layer formed by spraying on powder material.

With regard to possible configurations of cold gas spraying or the production of cold gas spray layers, reference is made to the literature, for example to "Review on Cold Spray Process and Technology Part I - Intellectual Property" (Irissou et al., Journal of Thermal Spray Technology, 17, 4, pp. 495-516, 2008).

The metal coating preferably has a layer thickness of less than 100 μm.

The material of the metal coating is preferably selected in such a way that the metal coating has a lower tendency to seizure and seizing than a metal coating consisting of the material of the rotor shaft or the machine element.

With a view to the transmission of high torques in normal operation and efficient overload protection in the event of short-circuit torques, it is considered advantageous if the rotor shaft and the machine element are made of steel and the metal coating is an alloy other than steel.

In a preferred embodiment it is provided that the metal coating is a copper layer or contains copper.

In another preferred embodiment it is provided that the metal coating is a layer of brass or bronze or contains brass or bronze.

With a view to efficient overload protection in the event of short-circuit torques, it is considered advantageous if the metal coating has a coefficient of elasticity that deviates by a maximum of ±10% from the coefficient of elasticity of the machine element and the rotor shaft.

In a preferred embodiment, it is provided that the outer surface of the rotor shaft is conical in the area of the machine element and the inner surface of the machine element is also conical there.

In another preferred embodiment, it is provided that the outer surface of the rotor shaft is cylindrical in the area of the machine element and the inner surface of the machine element is also cylindrical there.

The electrical machine is preferably a drive motor for a railway vehicle. In view of the problems mentioned at the outset with regard to torque peaks in drive motors, the invention also relates to a railroad vehicle which is equipped with an electric machine. In this regard, according to the invention, the machine is configured as described above.

With regard to the advantages and advantageous configurations of the railway vehicle according to the invention, the above statements apply accordingly in connection with the machine according to the invention and its advantageous configurations.

The invention also relates to a method for producing an electrical machine, in particular a machine of a railroad vehicle, with a rotor shaft being non-rotatably connected to a machine element in the method. According to the invention, before the rotor shaft and machine element are connected, a metal coating is applied to the rotor shaft, the machine element or to both of the parts mentioned, and the rotor shaft and the machine element are connected to one another after the metal coating has been applied, with the metal coating having an intermediate metal layer between of the rotor shaft and the machine element and allows an overload-related relative rotation between the machine element and the rotor shaft and the material of the metal coating differs from both the material of the rotor shaft and the material of the machine element.

With regard to the advantages and advantageous configurations of the method according to the invention, the above statements apply accordingly in connection with the machine according to the invention and its advantageous configurations.

It is advantageous if the metal coating is applied by spraying on powder material, in particular cold gas spraying.

The metal coating is preferably applied with a layer thickness of less than 100 μm.

It is also advantageous if the metal coating has a coefficient of elasticity that deviates from the coefficient of elasticity of the machine element and the rotor shaft by a maximum of ±10%.

Particularly suitable materials for the metal coating are copper, brass and bronze.

After the metal coating has been applied to the machine element or rotor shaft, the metal coating will preferably be on the outside tig removed, preferably by a machining process such as turning, whereby the outside diameter of the coated rotor shaft is reduced or the inside diameter of the coated machine element is increased.

• 1-5 ein Ausführungsbeispiel für ein Verfahren zum Herstellen einer Welle-Nabe-Verbindung mit einer Metallschicht als Zwischenschicht zum Überlastschutz und zur Reibschweißvermeidung, wobei die Welle an einem Wellenende zylindrisch ist und die Nabe durch ein Zahnrad gebildet wird und wobei die Zwischenschicht auf dem zylindrischen Wellenende aufgebracht wird,
• 6-10 ein Ausführungsbeispiel für ein Verfahren zum Herstellen einer Welle-Nabe-Verbindung mit einer Metallschicht als Zwischenschicht zum Überlastschutz und zur Reibschweißvermeidung, wobei die Welle an einem Wellenende konisch ist und die Nabe durch eine Hülse mit Flansch gebildet wird und wobei die Zwischenschicht auf dem konischen Wellenende aufgebracht wird,
• 11-15 ein Ausführungsbeispiel für ein Verfahren zum Herstellen einer Welle-Nabe-Verbindung mit einer Metallschicht als Zwischenschicht zum Überlastschutz und zur Reibschweißvermeidung, wobei eine Bohrung der Nabe zylindrisch ist und die Nabe durch ein Zahnrad gebildet wird und wobei die Zwischenschicht auf der zylindrischen Bohrung aufgebracht wird,
• 16-20 ein Ausführungsbeispiel für ein Verfahren zum Herstellen einer Welle-Nabe-Verbindung mit einer Metallschicht als Zwischenschicht zum Überlastschutz und zur Reibschweißvermeidung, wobei eine Bohrung der Nabe konisch ist und die Nabe durch eine Hülse mit Flansch gebildet wird und wobei die Zwischenschicht auf der konischen Bohrung aufgebracht wird, und
• 21-22 Ausführungsbeispiele für Welle-Nabe-Verbindungen mit Zwischenschichten auf Nabe und Welle.

The invention is explained in more detail below using exemplary embodiments; show examples

• 1-5 an embodiment of a method for producing a shaft-hub connection with a metal layer as an intermediate layer for overload protection and to avoid friction welding, the shaft being cylindrical at one shaft end and the hub being formed by a gear and the intermediate layer being applied to the cylindrical shaft end ,
• 6-10 an embodiment of a method for producing a shaft-hub connection with a metal layer as an intermediate layer for overload protection and to avoid friction welding, the shaft being conical at one shaft end and the hub being formed by a sleeve with a flange and the intermediate layer on the conical shaft end is raised,
• 11-15 an embodiment of a method for producing a shaft-hub connection with a metal layer as an intermediate layer for overload protection and to avoid friction welding, wherein a bore of the hub is cylindrical and the hub is formed by a gear and the intermediate layer is applied to the cylindrical bore,
• 16-20 an embodiment of a method for producing a shaft-hub connection with a metal layer as an intermediate layer for overload protection and friction welding prevention, wherein a bore of the hub is conical and the hub is formed by a sleeve with a flange and the intermediate layer is applied to the conical bore will, and
• 21-22 Examples of shaft-hub connections with intermediate layers on hub and shaft.

In the figures, the same reference numbers are always used for identical or comparable components.

the 1 shows a schematic cross section of a cylindrical section 11 of a rotor shaft 10 of an electrical machine, not shown in detail, before the application of a metal coating, which performs an overload protection function during subsequent operation of the electrical machine.

the 2 shows the cylindrical portion 11 of the rotor shaft 10 according to FIG 1 during the application of a metal coating or a metal layer 20, which is applied or deposited by means of cold gas spraying KGS and is therefore a cold gas spraying layer. The thickness of the sprayed metal layer 20 is preferably less than 100 μm.

the 3 FIG. 1 shows the coated cylindrical section 11 of the rotor shaft 10 according to FIG 2 during the post-processing NB of the surface of the sprayed metal layer 20. As part of the post-processing NB, for example, the surface can be polished to enable the overload protection to be triggered even at small torque peaks, or roughened to allow the overload protection to be triggered only at larger torque peaks .

As an alternative or in addition, the diameter of the coated section 11 can be set to a specified target dimension as part of the post-processing NB—for example by turning using a lathe—with very narrow tolerances being able to be maintained.

the 4 shows the reworked section 11 of the rotor shaft 10 with the reworked metal layer 21.

the 5 shows a machine element 30 in a schematic cross section, which has a cylindrical bore 31 and with this on the reworked section 11 of the rotor shaft 10 according to 4 has been postponed or forced on. During subsequent operation of the electrical machine, the metal layer 21 performs an overload protection function by acting as a kind of “slip layer” and enabling relative rotation between the machine element 30 and the rotor shaft 10; at the same time, it prevents or at least delays friction welding between the machine element 30 and the rotor shaft 10 in the event of relative rotation.

Connections between shafts and machine elements in the form shown are also technically referred to as shaft-hub connections, with the hub in 5 is formed by a gear 32.

In the embodiment according to 5 the machine element 30 can be uncoated on the inside 31a of the cylindrical bore 31 itself, as in FIG 5 shown; alternatively, the inside 31a of the cylindrical bore 31 can also be coated. In the latter execution tion form results in an arrangement with two metal layers in the 21 1 and identified by reference numerals 20a and 21a.

A screw connection 40 can also be provided for the axial fastening of the machine element 30, as shown in FIG 5 shown.

the 6 shows a schematic cross section of a conical section 12 of a rotor shaft 10 of an electrical machine, not shown in detail, before the application of a metal coating, which performs an overload protection function during subsequent operation of the electrical machine.

the 7 shows the conical section 12 of the rotor shaft 10 according to FIG 6 during the application of a metal layer 20 in the form of a cold spray layer by means of cold spray KGS. The thickness of the sprayed metal layer 20 is preferably less than 100 μm.

the 8th shows the coated conical section 12 of the rotor shaft 10 according to FIG 7 during the post-processing NB of the surface of the sprayed metal layer 20. As part of the post-processing NB, for example, the surface can be polished to enable the overload protection to be triggered even at small torque peaks, or roughened to allow the overload protection to be triggered only at larger torque peaks .

As an alternative or in addition, the diameter of the coated section 12 can be set to a predetermined target dimension as part of the post-processing NB—for example by turning using a lathe—with very narrow tolerances being able to be maintained.

the 9 shows the reworked section 12 of the rotor shaft 10 with the reworked metal layer 21.

the 10 shows a machine element 30 in a schematic cross section, which has a conical bore 31 and with this on the reworked section 12 of the rotor shaft 10 according to FIG 9 has been postponed or forced on. In the embodiment according to 10 forms the machine element 30, which is formed by a sleeve 33 with a flange 34, the hub of a shaft-hub connection.

The metal coating exercises in the arrangement according to 10 during subsequent operation of the electric machine, it performs an overload protection function by acting as a kind of "slip layer" and enabling relative rotation between the machine element 30 and the rotor shaft 10; at the same time, it prevents or at least delays friction welding between the machine element 30 and the rotor shaft 10 in the event of relative rotation.

The machine element 30 according to 10 can be uncoated in the area of the conical bore 31 itself, as in 10 shown; alternatively, the machine element 30 can also be coated with a metal coating in the area of the conical bore 31 . In the latter embodiment, there is an arrangement with two metal layers in the 22 are shown and identified by the reference numerals 20a and 21a.

A screw connection 40 can be provided for the axial fastening of the machine element 30, as in 10 shown.

the 11 shows a schematic cross section of a cylindrical bore 31 of a machine element 30 of an electrical machine, not shown in detail, before the application of a metal coating, which performs an overload protection function during subsequent operation of the electrical machine. The machine element 30 can be a gear wheel 32, for example.

the 12 shows the cylindrical bore 31 according to FIG 11 during the application of a metal coating in the form of a metal layer 20a, which is applied or deposited by means of cold gas spraying KGS, in other words is a cold gas spraying layer. The thickness of the sprayed metal layer 20a is preferably less than 100 μm.

the 13 shows the coated bore 31 according to FIG 12 during the post-processing NB of the surface of the sprayed metal layer 20a. As part of the post-processing NB, for example, the surface can be polished to enable the overload protection to be triggered even at small torque peaks, or roughened to allow the overload protection to be triggered only at larger torque peaks.

As an alternative or in addition, the diameter of the coated section 11 can be set to a specified target dimension as part of the post-processing NB—for example by turning using a lathe—with very narrow tolerances being able to be maintained.

the 14 shows the hole 31 with the post-processed metal layer 21a after completion of the post-processing NB.

the 15 shows in a schematic cross section the reworked machine element 30 according to FIG 14 after it has been slid or pressed onto a rotor shaft 10 . The post-processed metal layer 21a exerts an overload protection function during later operation of the electrical machine by acting as a kind of “slip layer” and enabling relative rotation between the machine element 30 and the rotor shaft 10; at the same time, it prevents or at least delays friction welding between the machine element 30 and the rotor shaft 10 in the event of relative rotation.

In the embodiment according to 15 the rotor shaft 10 itself can be uncoated, as in 15 shown; Alternatively, the rotor shaft 10 can also be coated, for example, as in connection with 1 until 5 explained above. In the latter embodiment, there is an arrangement with two metal layers in the 21 are shown and identified by the reference numerals 20a and 21a.

A screw connection 40 can be provided for the axial fastening of the machine element 30, as in 15 is shown.

the 16 shows a schematic cross section of a conical bore 31 of a machine element 30 of an electrical machine, not shown in detail, before the application of a metal coating, which performs an overload protection function during subsequent operation of the electrical machine. The machine element 30 can be, for example, a sleeve 33 with a flange section 34 .

the 17 shows the conical bore 31 according to FIG 16 during the application of a metal coating in the form of a metal layer 20a, which is applied or deposited by means of cold gas spraying KGS, in other words is a cold gas spraying layer. The thickness of the sprayed metal layer 20a is preferably less than 100 μm.

the 18 shows the coated bore 31 according to FIG 17 during the post-processing NB of the surface of the sprayed metal layer 20a. As part of the post-processing NB, for example, the surface can be polished to enable the overload protection to be triggered even at small torque peaks, or roughened to allow the overload protection to be triggered only at larger torque peaks.

As an alternative or in addition, the diameter of the coated section 11 can be set to a specified target dimension as part of the post-processing NB—for example by turning using a lathe—with very narrow tolerances being able to be maintained.

the 19 shows the hole 31 with the post-processed metal layer 21a after completion of the post-processing NB.

the 20 shows in a schematic cross section the reworked machine element 30 according to FIG 19 after it has been slid or pressed onto a rotor shaft 10 . The post-processed metal layer 21a exerts an overload protection function during later operation of the electrical machine by acting as a kind of “slip layer” and enabling relative rotation between the machine element 30 and the rotor shaft 10; at the same time, it prevents or at least delays friction welding between the machine element 30 and the rotor shaft 10 in the event of relative rotation.

In the embodiment according to 20 the rotor shaft 10 itself can be uncoated, as in 20 shown; Alternatively, the rotor shaft 10 can also be coated, for example, as in connection with 1 until 5 explained above. In the latter embodiment, there is an arrangement with two metal layers in the 22 are shown and identified by the reference numerals 20a and 21a.

A screw connection 40 can be provided for the axial fastening of the machine element 30, as in 20 is shown.

The in the 5 , 10 , 15 , 20 , 21 and 22 Arrangements shown preferably form components of an electrical machine not shown for reasons of clarity, for example a drive motor of a railway vehicle.

Although the invention has been illustrated and described in detail by means of preferred exemplary embodiments, the invention is not limited by the disclosed examples and other variations can be derived therefrom by a person skilled in the art without departing from the protective scope of the invention.

reference list

10

rotor shaft

11

cylindrical section

12

conical section

20

metal layer

20a

metal layer

21

finished metal layer

21a

metal layer

30

machine element

31

cylindrical bore

31a

inside

32

gear

33

sleeve

34

flange

40

screw connection

NB

post processing

KGS

cold gas spraying

Claims (15)

Electrical machine with - a stator, - a rotor shaft (10) and - a machine element (30) placed on the rotor shaft (10), characterized in that - at least in the area between the rotor shaft (10) and the machine element (30) on the A metal coating (20) is applied to the rotor shaft (10), the machine element (30) or to both of the parts mentioned, which forms an intermediate metal layer between the rotor shaft (10) and the machine element (30) and overload-related relative rotation between the machine element (30) and the rotor shaft (10), - the material of the metal coating (20) differing both from the material of the rotor shaft (10) and from the material of the machine element (30). Electric machine after claim 1 , characterized in that the metal coating (20) is a sprayed cold gas sprayed layer. Electrical machine according to one of the preceding claims, characterized in that the metal coating (20) has a layer thickness of less than 100 µm. Electrical machine according to one of the preceding claims, d characterized in that the material of the metal coating (20) has a lower tendency to friction welding or seizure with the material of the rotor shaft (10) and the material of the machine element (30) than a coating of the Material of the rotor shaft (10) or the machine element (30) would have. Electrical machine according to one of the preceding claims, characterized in that the rotor shaft (10) and the machine element (30) are made of steel and the metal coating (20) is an alloy other than steel. Electrical machine according to one of the preceding claims, characterized in that the metal coating (20) is a copper layer or contains copper. Electrical machine according to one of the preceding claims, characterized in that the metal coating (20) is a layer of brass or bronze or contains brass or bronze. Electrical machine according to one of the preceding claims, characterized in that the metal coating (20) has a coefficient of elasticity which deviates at most ± 10% from the coefficient of elasticity of the machine element (30) and the rotor shaft (10). Electrical machine according to one of the preceding claims, characterized in that - the outer surface of the rotor shaft (10) in the area of the machine element (30) is conical and the inner surface of the machine element (30) opposite the outer surface is also conical there or - the outer surface of the rotor shaft (10) is cylindrical in the area of the machine element (30) and the inner surface of the machine element (30) opposite the outer surface is also cylindrical. Railway rail vehicle with an electrical machine, characterized in that the machine is a machine according to one of the preceding claims. Method for producing an electrical machine, in particular a machine of a railroad vehicle, in which method a rotor shaft (10) is non-rotatably connected to a machine element (30), characterized in that - before the rotor shaft (10) and machine element (30) are connected a metal coating (20) is applied to the rotor shaft (10), the machine element (30) or to both of said parts, and - the rotor shaft (10) and the machine element (30) are connected to one another after the metal coating (20) has been applied - Wherein the metal coating (20) forms a metal intermediate layer between the rotor shaft (10) and the machine element (30) and a Überlastbe conditioned relative rotation between the machine element (30) and the rotor shaft (10) and - wherein the material of the metal coating (20) differs both from the material of the rotor shaft (10) and from the material of the machine element (30). procedure after claim 11 , characterized in that the metal coating (20) by spraying powder material, in particular cold gas spraying (KGS), is applied. Method according to any of the foregoing Claims 11 until 12 , characterized in that the metal coating (20) is applied with a layer thickness of less than 100 µm. Method according to any of the foregoing Claims 11 until 13 , characterized in that the metal coating (20) has a coefficient of elasticity which deviates from the coefficient of elasticity of the machine element (30) and the rotor shaft (10) by a maximum of ± 10%. Method according to any of the foregoing Claims 11 until 14 , characterized in that after the metal coating (20) has been applied to the machine element (30) or the rotor shaft (10), the metal coating (20) is removed on the outside, preferably by a machining process such as turning, with the outer diameter of the coated rotor shaft (10) is reduced or the inner diameter of the coated machine element (30) is increased.

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