DE102019120943A1 - Method for coating a component of an electrical machine - Google Patents

Abstract

The invention relates to a method for coating a component of an electrical machine, the component being a stator or a rotor, the component having a base body and a wire winding, the base body having a plurality of radially extending teeth , whereby a recess is formed between two adjacent teeth, a wire winding being arranged in the respective recess, the wire winding and the base body being electrically isolated from one another. The method comprises the following method steps: - providing the component, - providing a spray device for Applying a coating material to the component, applying a first electrical potential to the base body, applying a second electrical potential to the wire winding, the first electrical potential and the second electrical potential being different, applying e a third electrical potential on the spray device such that the coating material sprayed by means of the spray device is electrically charged, - application of the coating material to the component by means of the spray device. This method enables a defined paint profile to be generated within the recesses.

Description

The invention relates to a method for coating a component of an electrical machine, the component being a stator or a rotor.

The stator and / or the rotor of a conventional electrical machine for higher voltages has a plurality of radially extending teeth, with a recess being formed between each two adjacent teeth. A wire winding is arranged in the respective recess. The wire winding and the base body are electrically isolated from one another.

The pamphlets US 2003/0113441 A1 , US 2006/0177593 A1 and WO 2016/124523 A1 each disclose a method for powder coating a stator of an electrical machine with an electrically insulating material.

In the US 2002/0182311 A1 describes a method for manufacturing electromagnetic components by means of powder coating.

The US 2008/0152786 A1 discloses a method for powder coating of winding wire ends of an electrical machine by means of powder coating.

The object of the present invention is to develop a method of the type mentioned at the beginning, which has the features of the preamble of claim 1, in such a way that a defined lacquer profile can be generated within the recesses.

The object is achieved by a method which has the features of claim 1.

The invention thus proposes a method for coating a component of an electrical machine. This component is a stator or a rotor. The component has a base body and a wire winding. The main body has a plurality of radially extending teeth.

A recess is formed between two adjacent teeth. The wire winding is arranged in the respective recess. The wire winding and the base body are electrically isolated from one another. In this method for coating the component of the electrical machine, the component and a spray device for applying a coating material to the component are provided. A first electrical potential is applied to the base body and a second electrical potential is applied to the wire winding. The first electrical potential and the second electrical potential are different. A third electrical potential is applied to the spray device in such a way that the coating material sprayed by means of the spray device is electrically charged. The coating material is applied to the component by means of the spray device.

Three electrical potentials are thus used to set the coating, namely the electrical potential of the base body, the electrical potential of the wire winding and the electrical potential of the spray device. At least two of the three elements are charged accordingly by voltage sources, the third element can be connected to earth. The charged particles of the coating material are attracted accordingly by the wire winding and the base body. The arrangement used in the method makes use of the fact that the wire winding is electrically insulated from the base body, in particular insulated for a voltage in the order of magnitude of several kilovolts, and can accordingly be charged differently. If the voltage difference between the spray device and the wire winding is increased, a larger part of the coating material is also deposited there. In order to increase this effect, the stator or the rotor can even be charged in opposite directions in order to even repel the coating material, in particular a paint mist or paint dust. Coating profiles can be generated in particular under the aspect that the coating material has aerosol droplets, for example in the case of liquid paint or particles of powder paint. The aerosol droplets are mainly influenced by three forces in their path, namely their weight forces, acting electrostatic forces and an air flow. If the voltages are sufficiently high and there is hardly any air flow, the droplets or particles largely follow the electric field lines. By suitable selection of the charging voltages of the wire winding and the base body, field profiles can be set that lead to a desired thickness profile. For a layer thickness increasing towards the edges of the recesses, it is necessary to set the field in such a way that the voltage difference between the spray device and the base body is greater than that between the spray device and the wire winding. In this case, a large amount of coating material also collects accordingly on the surface of the stator or rotor facing the air gap between stator and rotor. This may then have to be removed to prevent the rotor and stator from grinding when the electrical machine is in operation.

In particular, from a magnetic point of view, the coating material applied to the component by means of the spray device should be thinner in the center of the recess, which is usually a groove, than at the edges. This prevents a magnetically highly conductive path from forming for a transverse field from one tooth to the next tooth of one component, in particular of the stator, which would magnetically short-circuit the teeth and thus prevent the desired path via the other component, i.e. the rotor would. Instead, leakage fluxes from the poles of the other component, i.e. the rotor poles, which could otherwise run into the open slot and the conductors, are deflected more quickly to the edges of the recess in the base body due to the higher magnetic conductivity and thus prevented from flowing eddy currents in the conductors produce. Due to the profile, the short-circuited transverse path through the coating material not only has a higher resistance, but also tends to lead to magnetic saturation due to a higher flux density in the thinner area, whereby the effective μ there drops and the magnetic path is further weakened significantly.

In the method, the electrical potentials are thus selected in particular in such a way that a defined coating profile is generated.

In particular, the base body, the wire winding and the sprayed coating material are electrostatically charged.

In particular, it is provided here that the base body and the sprayed coating material are charged differently, preferably oppositely charged.

In particular, the potential difference between the spray device and the base body is smaller than a potential difference between the spray device and the wire winding.

The recesses, in particular grooves, are designed in particular such that they have an opening in the radial direction.

The wire winding is designed in particular in such a way that it has a plurality of winding phases, an electrical potential that is different from another winding phase being applied to one winding phase.

The coating material is preferably a powder coating or a liquid coating.

The coating material is in particular a soft magnetic material or has a soft magnetic material.

The coating material is in particular ferrimagnetic or has ferrimagnetic material.

The soft magnetic particles can for example be ferrimagnetic (more typically ferrimagnetic materials, for example ferrites such as iron oxides), which offer the advantage of a lack of electrical conduction and a relatively high magnetic conduction. Paramagnetics, which have a lower magnetic conductivity, can be used less advantageously.

Alternatively, ferromagnetic materials can also be used, but these are mostly electrically conductive (elementary ferromagnetic materials Fe Ni Co) and should therefore be individually coated with an insulating coating before they are embedded in the coating material, especially in the paint matrix.

For example, the ferromagnetic particles can be small enough to have a superparamagnetic effect and thus not form more than one Weiss area at normal operating temperatures.

The magnetic permeability of the coating material, in particular paint, is selected in particular so that it is lower than that of solid silicon steel, as is usually used for the stator iron. A lower permeability can be very advantageous in the present case, because the coating material or the lacquer should only effect a field formation of the stator field in the air gap and a shielding of the rotor field, but not a magnetic short circuit for the stator field from tooth to tooth past the rotor.

• - magnetische Permeabilität µ_r des Beschichtungsmaterials bzw. Lackes
• - Sättigungsflussdichte des Beschichtungsmaterials bzw. Lackes,
• - Dicke der Schicht des Beschichtungsmaterials bzw. Lacks,
• - bei Verwendung von Flüssiglack: Ausnutzung von Kapillarwirkung über Oberflächenspannung für eine zur Mitte jeder Aussparung bzw. Nut abnehmenden Dicke,
• - bei Verwendung von Pulverlack: jeweilige Spannungen der Drahtwicklung und des Statorstahls, um unterschiedliche elektrostatische Anziehung des Pulvers durch die Aussparung bzw. Nut, die Ränder der Aussparung und den Grundkörper bzw. das Eisen einzustellen.

Under the aspect of these developments of the invention, there are several degrees of freedom for the coating:

• - Magnetic permeability µ _{r of} the coating material or lacquer
• - saturation flux density of the coating material or lacquer,
• - thickness of the layer of coating material or lacquer,
• - when using liquid varnish: use of capillary action via surface tension for a thickness that decreases towards the center of each recess or groove,
• - when using powder coating: respective voltages of the wire winding and the Stator steel in order to set different electrostatic attraction of the powder through the recess or groove, the edges of the recess and the base body or the iron.

According to an advantageous development of the method, it is provided that after the coating material has been applied to the component, the coating material is cured and / or crosslinked and / or sintered by means of the supply of heat. In particular, it can be provided that the heat is supplied at least partially in that the wire winding is subjected to an electrical current.

In particular, non-hardened and / or non-crosslinked and / or non-sintered coating material is removed from the component.

The end faces of the teeth of the coated component are preferably free of a coating. The tooth crowns are therefore bare.

From the aspect of coating the component with the supply of heat, it is considered particularly advantageous if the heat required for crosslinking is generated by current flow in the motor winding. This means that the coating material that is located near the wire winding heats up significantly further and is particularly strong. With a suitable choice of the ambient temperature and, if necessary, a targeted air flow and the current intensity through the wire winding, it can be set that only the coating material in the recess or groove has sufficient temperature or activation energy for crosslinking. The uncured coating material, in particular uncured paint or powder, can then be brushed off, washed off or otherwise removed.

The coating is formed by applying the coating material to the component.

In particular, it is provided that the coating is applied in such a way that the coating applied in the region of the recess covers the wire winding arranged in the recess in the radial direction.

In particular, a layer thickness of the coating applied in the area of the recess has a greater layer thickness in an edge area adjoining the teeth than in a central area.

Further features of the invention emerge from the subclaims, the attached drawing and the exemplary embodiments reproduced in the drawing, without being restricted thereto.

• 1 in stark vereinfachter Darstellung eine Anordnung zur Durchführung des Verfahrens bei einer ersten Verfahrensweise,
• 2 in stark vereinfachter Darstellung eine Anordnung zur Durchführung des Verfahrens bei einer zweiten Verfahrensweise,
• 3 in stark vereinfachter Darstellung eine Anordnung zur Durchführung des Verfahrens bei einer dritten Verfahrensweise,
• 4 in schematischer Darstellung eine Anordnung des verfahrensrelevanten Bereichs einer elektrischen Maschine.

It shows:

• 1 in a greatly simplified representation, an arrangement for carrying out the method in a first method,
• 2 in a greatly simplified representation an arrangement for carrying out the method in a second method,
• 3 in a greatly simplified representation an arrangement for carrying out the method in a third method,
• 4th a schematic representation of an arrangement of the process-relevant area of an electrical machine.

Figure description

4th shows a sub-area of an electrical machine relevant to the description of the method according to the invention 1 which is used in particular to drive a partially or exclusively electrically powered vehicle, in particular a passenger vehicle. Two components of the electrical machine are shown 1 , namely a stator 2 and a rotor 3 , each for a sub-area in the stator 2 and rotor 3 when a small air gap is formed 4th opposite. Here the invention is only related to the stator 2 illustrated. Accordingly, the invention can also or only in the area of the rotor 3 be realized.

The stator 2 has a base body 5 with a plurality of radially extending teeth 6 on. Between two adjacent teeth 6 , 6 is each a recess 7th designed in the form of a groove. In the respective recesses 7th is a wire winding 8th arranged. This and the main body 5 are electrically isolated from each other.

The respective recess is closed 7th by means of a coating 9 . This covers the area of the recess 7th applied coating 9 those in the recess 7th arranged wire winding 8th in the radial direction, towards the rotor 3 down, down. The layer thickness, thus radial thickness, that in the area of the recess 7th applied coating 9 is in one to the teeth 6 adjacent edge area is designed so that it has a greater layer thickness than in a central area between the teeth 6 . Is shown in 4th that the coating 9 also in the area of the end faces 10 the teeth 6 extends. It is preferred if these end faces 10 the teeth 6 free from the coating 9 are, thus the frontal bare teeth 6 directly to the air gap 4th adjoin.

• - Bereitstellen der Komponente 2 bzw. 3, wobei die Komponente 2 bzw. 3 den Grundkörper 5 mit der Vielzahl von sich radial erstreckenden Zähnen 6 aufweist, wobei zwischen zwei benachbarten Zähnen 6 jeweils die eine Aussparung 7 ausgebildet ist, wobei in der jeweiligen Aussparung 7 die Drahtwicklung 8 angeordnet ist, wobei die Drahtwicklung 8 und der Grundkörper 5 voneinander elektrisch isoliert sind,
• - Bereitstellen einer Sprühvorrichtung 11 zum Aufbringen eines Beschichtungsmaterials 12 auf die Komponente 2 bzw. 3,
• - Anlegen eines ersten elektrischen Potentials an dem Grundkörper 5,
• - Anlegen eines zweiten elektrischen Potentials an der Drahtwicklung 8, wobei das erste elektrische Potential und das zweite elektrische Potential unterschiedlich sind,
• - Anlegen eines dritten elektrischen Potentials an der Sprühvorrichtung 11 derart, dass das mittels der Sprühvorrichtung 11 versprühte Beschichtungsmaterial 12 elektrisch geladen wird,
• - Aufbringen des Beschichtungsmaterials 12 auf die Komponente 2 bzw. 3 mittels der Sprühvorrichtung 11.

The process for coating the component, be it for the electrical machine 1 according to 4th who have made the coating 9 of the stator 2 shows, or for the coating of the rotor 3 includes the following process steps, as described with reference to the parts required to carry out the process in the 1 to 3 illustrated is:

• - Deploy the component 2 or. 3 , where the component 2 or. 3 the main body 5 with the plurality of radially extending teeth 6 having, between two adjacent teeth 6 each one recess 7th is formed, in the respective recess 7th the wire winding 8th is arranged, the wire winding 8th and the main body 5 are electrically isolated from each other,
• - Provision of a spray device 11 for applying a coating material 12 on the component 2 or. 3 ,
• - Applying a first electrical potential to the base body 5 ,
• - Applying a second electrical potential to the wire winding 8th , where the first electrical potential and the second electrical potential are different,
• - Applying a third electrical potential to the spray device 11 such that that by means of the spray device 11 sprayed coating material 12 is electrically charged,
• - Application of the coating material 12 on the component 2 or. 3 by means of the spray device 11 .

The electrical potentials are selected in such a way that a defined coating profile is generated.

The basic body 5 who have favourited Wire Wrapping 8th and the sprayed coating material 12 are electrostatically charged. The basic body 5 and the sprayed coating material 12 are charged differently, preferably oppositely charged. A potential difference between the spray device 11 and the main body 5 is smaller than a potential difference between the spray device 11 and the wire winding 8th .

The recesses 7th have an opening in the radial direction.

With the coating material 12 it is a powder coating or a liquid coating. The coating material is a soft magnetic material or has soft magnetic material. The coating material 12 is ferrimagnetic or has ferrimagnetic material.

The wire winding 8th has several strands of winding 13 on, being on a winding strand 13 a different potential from another winding phase is applied.

After applying the coating material 12 on the component 2 or. 3 becomes the coating material 12 cured and / or crosslinked and / or sintered by means of heat supply. The heat is supplied at least in part by the wire winding 8th is applied with an electric current. Uncured and / or not crosslinked and / or not sintered coating material 12 is from the component 2 or. 3 away. In particular, the end faces 10 the teeth 6 the coated component 2 or. 3 free of any coating.

In the embodiments in the 1 , 2 and 3 illustrated is the wire winding 8th each applied to a constant relative potential, in this case to earth. To the main body 5 and to the spray device 11 are potentials that deviate from this earth potential, specifically different potentials.

In the embodiment according to 1 tells the spray device 11 applied electrical potential has a greater potential difference to earth than that to the base body 5 applied electrical potential and there are different voltage levels of wire winding 8th and base body 5 . This is when the coating material is applied 12 a coating 9 in the area of the open end of the recess 7th formed according to the in 1 coating shown 9 is trained.

2 shows a modification to 1 in that, by applying an opposite voltage, the coating material is repelled 12 from the main body 5 he follows.

The embodiment according to 3 illustrates that to the spray device 11 applied electrical potential has a greater potential difference to earth than that to the base body 5 applied electrical potential. Thus, a reduced thickness of the coating 9 in a central area of the coating 9 or a central area of the respective recess 7th between adjacent teeth 6 can be generated.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed 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

• US 2003/0113441 A1 [0003]
• US 2006/0177593 A1 [0003]
• WO 2016/124523 A1 [0003]
• US 2002/0182311 A1 [0004]
• US 2008/0152786 A1 [0005]

Claims (16)

Method for coating a component (2, 3) of an electrical machine (1), the component (2, 3) being a stator (2) or a rotor (3), the component (2, 3) has a base body (5) and a wire winding (8), the base body (5) having a plurality of radially extending teeth (6), a recess (7) being formed between two adjacent teeth (6, 6), the wire winding (8) being arranged in the respective recess (7), the wire winding (8) and the base body (5) being electrically isolated from one another, characterized by the following method steps: - providing the component (2, 3), - providing a spray device (11) for applying a coating material (12) to the component 2, 3), - applying a first electrical potential to the base body (5), - applying a second electrical potential to the wire winding (8), the first being electrical potential and the second electrical potential are different, - application of a third electrical potential to the spray device (11) such that the coating material (12) sprayed by means of the spray device (11) is electrically charged, - application of the coating material (12) to the component ( 2, 3) by means of the spray device (11). Procedure according to Claim 1 , characterized in that the base body (5), the wire winding (8) and the sprayed coating material (12) are electrostatically charged. Procedure according to Claim 2 , characterized in that the base body (5) and the sprayed coating material (12) are charged differently. Procedure according to Claim 3 , characterized in that the base body (5) and the sprayed coating material (12) are charged in opposite directions. Method according to one of the Claims 1 to 4th , characterized in that a potential difference between the spray device (11) and the base body (5) is smaller than a potential difference between the spray device (11) and the wire winding (8). Method according to one of the Claims 1 to 5 , characterized in that the recesses (7) have an opening in the radial direction. Method according to one of the Claims 1 to 6 , characterized in that the coating material (12) is a powder coating or a liquid coating. Method according to one of the Claims 1 to 7th , characterized in that the coating material (12) is a soft magnetic material or has soft magnetic material. Method according to one of the Claims 1 to 8th , characterized in that the coating material (12) is ferrimagnetic or comprises ferrimagnetic material. Method according to one of the Claims 1 to 9 , characterized in that the wire winding (8) has a plurality of winding strands (13), an electrical potential that is different from another winding strand (13) being applied to one winding strand (13). Method according to one of the Claims 1 to 10 , characterized in that after the coating material (12) has been applied to the component (2, 3), the coating material (12) is cured and / or crosslinked and / or sintered by means of supply of heat. Procedure according to Claim 11 , characterized in that the heat is supplied at least partially in that the wire winding (8) is subjected to an electrical current. Procedure according to Claim 11 or 12 , characterized in that uncured and / or not crosslinked and / or not sintered coating material (12) is removed from the component (2, 3). Method according to one of the Claims 1 to 13 , characterized in that the end faces (10) of the teeth (6) of the coated component (2, 3) are free of a coating. Method according to one of the Claims 1 to 14th , characterized in that the coating (9) is applied in such a way that the coating (9) applied in the region of the recess (7) covers the wire winding (8) arranged in the recess (7) in the radial direction. Method according to one of the Claims 1 to 15th , characterized in that a layer thickness of the coating (7) applied in the region of the recess (7) has a greater layer thickness in an edge region adjoining the teeth (6) than in a central region.

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