DE102021100910A1 - Process for stacking electrical steel sheets and electrical machine - Google Patents

Abstract

The invention relates to a method for stacking electrical steel sheets (1), in particular for use in electrical machines (2) in hybrid or all-electric drive trains (3) of motor vehicles (4), comprising the following steps: providing an electrical steel sheet (1), Providing a free-flowing pressure-sensitive adhesive (5), coating at least a first metal sheet side (6) of the electrical steel sheet (1) with the pressure-sensitive adhesive (5) at a temperature of the electrical steel sheet (1) between 10°C-80°C, preferably 10°C-45 °, particularly preferably at room temperature, assembling the electrical sheets (1) to connect them via the adhesive (5) at a temperature of the electrical sheets (1) between 10 ° C-80 ° C, preferably 10 ° C-45 °, particularly preferably at Room temperature, pressing of the electrical laminations (1) to form an electrical laminations (7) at a temperature between 10° C.-80° C., preferably 10° C.-45°, particularly preferably at room temperature.

Description

The present invention relates to a method for stacking electrical laminations, in particular for use in electrical machines in hybrid or all-electric drive trains in motor vehicles, and an electrical machine.

It is known from the prior art that stators and/or rotors of electrical machines comprise stacks of laminations which, compared to a solid material, have the advantage of preventing eddy currents and thus increasing the efficiency of the electrical machine.

Laminated cores of this type are formed from a plurality of laminated individual laminations, which are generally made from electrical steel sheet and are stacked and packaged one on top of the other to form a stack, the so-called laminated core. The individual laminations can then remain held together in the laminated core by gluing, welding or wedging or screwing or the like.

When gluing electrical laminations, there is the problem that the adhesive usually requires some time to harden, which limits the process or production speed of such laminated cores. Thermal measures or UV light are often used to support the curing of the adhesive, which is comparatively energy-intensive and therefore expensive and undesirable from an environmental point of view.

It is therefore the object of the present invention to provide a method for stacking electrical laminations that overcomes the limitations mentioned and increases the process speed in the manufacture of electrical laminations and reduces the energy consumption in the manufacturing process. It is also the object of the invention to realize an electrical machine which has an optimized laminated core.

• • Bereitstellen eines Elektroblechs,
• • Bereitstellen eines fließfähigen Haftklebstoffs,
• • Beschichtung wenigstens einer ersten Blechseite des Elektroblechs mit dem Haftklebstoff bei einer Temperatur des Elektroblechs zwischen 10°C-80°C, bevorzugt 10°C-45°, insbesondere bevorzugt bei Raumtemperatur,
• • Zusammenfügen der Elektrobleche zum Verbinden dieser über den Haftklebstoff bei einer Temperatur der Elektrobleche zwischen zwischen 10°C-80°C, bevorzugt 10°C-45°, insbesondere bevorzugt bei Raumtemperatur,
• • Verpressen der Elektrobleche zu einem Elektroblechpaket bei einer Temperatur zwischen 10°C-80°C, bevorzugt 10°C-45°, insbesondere bevorzugt bei Raumtemperatur.

This object is achieved by a method for stacking electrical steel sheets, in particular for use in electrical machines in hybrid or all-electric drive trains of motor vehicles, comprising the following steps:

• • Provision of an electrical sheet,
• • providing a free-flowing pressure-sensitive adhesive,
• • Coating of at least a first metal sheet side of the electrical steel sheet with the pressure-sensitive adhesive at a temperature of the electrical steel sheet between 10° C.-80° C., preferably 10° C.-45° C., particularly preferably at room temperature,
• • Assembling the electrical sheets to connect them via the adhesive at a temperature of the electrical sheets between between 10 ° C-80 ° C, preferably 10 ° C-45 °, particularly preferably at room temperature,
• • Pressing the electrical laminations to form an electrical laminations at a temperature between 10° C.-80° C., preferably 10° C.-45°, particularly preferably at room temperature.

It has been shown that the use of a pressure-sensitive adhesive makes it possible to join the electrical steel sheets with very short pressing strokes. In particular, a curing time within the manufacturing process does not have to be taken into account. The manufacturing process can thus be designed much faster. There is also no need for thermal post-treatments, such as are necessary when using baked lacquer, so that the method according to the invention can also be carried out in a significantly more energy-efficient manner. Consequently, the process according to the invention also requires fewer or no investments in plant parts that provide thermal aftertreatment.

It is particularly preferred if the pressure-sensitive adhesive is not electrically conductive. As a result, a separate insulation layer for the electrical steel sheets can then be dispensed with, for example. In principle, it is of course possible for the electrical steel sheets to have an insulating layer, to which the pressure-sensitive adhesive is then applied.

Within the process, the electrical sheets can be actively tempered to the specified temperature intervals in one or all of the process steps. However, it is also possible and also preferred for the electrical steel sheets to have the temperature of the process environment.

It is of course also possible for the first side of the metal sheet and a second side of the metal sheet opposite the first side of the metal sheet to be coated with the pressure-sensitive adhesive, as a result of which the adhesive effect of the pressure-sensitive adhesive can be further improved.

In principle, it is possible for the electrical laminations to be punched before coating and/or before joining. Stamping can in particular bring about the formation of grooves distributed over the circumference and running parallel to the rotor shaft of an electrical machine, or circumferentially closed recesses which can accommodate the stator winding or parts of the stator winding.

The coating of the electrical sheets with the pressure-sensitive adhesive can take place in the direction of gravity and/or counter to the direction of gravity. special Particularly preferred is the coating of the electrical sheets with the pressure-sensitive adhesive in the direction of gravity.

According to an advantageous embodiment of the invention, it can be provided that the pressure-sensitive adhesive is essentially free of solvent. The advantage of this configuration is that the adhesion and the environmental compatibility of the pressure-sensitive adhesive are improved.

According to a further preferred further development of the invention, it can also be provided that the pressure-sensitive adhesive contains a polyvinyl butyral, which has been shown to be particularly advantageous with regard to the adhesion effect and coatability.

Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that the pressure-sensitive adhesive has a viscosity of 0.2-100 mPa*sec at room temperature. The advantageous effect of this configuration is based on the fact that the pressure-sensitive adhesive can be applied to the electrical laminations in a particularly advantageous manner in order to form the coating.

According to a further particularly preferred embodiment of the invention, it can be provided that the pressure-sensitive adhesive has a glass transition temperature of <−10° C., so that this results in a particularly good adhesion effect of the pressure-sensitive adhesive.

Furthermore, the invention can also be further developed such that the coating by means of the pressure-sensitive adhesive has an average layer thickness of 1-20 μm, preferably 2-7 μm, as a result of which a particularly advantageous compromise between adhesive effect, adhesive consumption and process speed can be achieved.

In a likewise preferred embodiment variant of the invention, provision can also be made for the pressure-sensitive adhesive to be applied at least in sections to at least the first metal sheet side of the electrical steel sheet by means of a spraying process. Pressure atomizers can preferably be used for spraying on the pressure-sensitive adhesive, which apply the pressure-sensitive adhesive using a compressor using the low-pressure (0.5-0.7 bar), high-pressure (1-8 bar) or airless method (60-250 bar).

It can also be advantageous to further develop the invention in such a way that the pressure-sensitive adhesive is applied at least in sections to at least the first metal sheet side of the electrical steel sheet by means of a printing process. The printing process can be selected from the group consisting of pad printing, stamp printing, embossing, screen printing, inkjet printing or the like.

According to a further preferred embodiment of the subject matter of the invention, it can be provided that the pressure-sensitive adhesive is applied at least in sections to at least the first metal sheet side of the electrical steel sheet by means of a rolling or brushing process.

Of course, it is also possible for the coating to be produced by using a combination of the above application methods, which is carried out at the same time or at different times.

It is particularly advantageous that the method is carried out in such a way that the pressing lasts between 1/60-1/800 min, preferably 1/200-1/600 min, particularly preferably 1/150-1/400 min, whereby an extremely faster production process for stacking of electrical sheets can be realized.

Finally, the invention can also be implemented in an advantageous manner such that the pressing of the electrical laminations to form an electrical laminations takes place at pressures of between 0.5-5 MPa.

The object of the invention is also achieved by an electrical machine, in particular for use in hybrid or all-electric drive trains of motor vehicles, comprising a stator and a rotor, the stator having a stacked electrical lamination stack with a plurality of electrical lamination sheets, at least one of which is located opposite one another Electrical laminations has a coating with a pressure-sensitive adhesive and/or the rotor has a stacked electrical laminations with a plurality of electrical laminations, wherein at least one of opposite electrical laminations has a coating with a pressure-sensitive adhesive.

The stator of an electrical machine is particularly preferably constructed cylindrically. The stator has a stator body which generally consists of electrical laminations which are electrically insulated from one another and are constructed in layers and packaged to form laminations. This structure keeps the eddy currents in the stator caused by the stator field low. Distributed over the circumference, grooves or peripherally closed recesses are let into the electrical lamination running parallel to the rotor shaft and accommodate the stator winding or parts of the stator winding. Depending on the construction towards the surface, the slots can be closed with locking elements such as locking wedges or covers or the like in order to prevent the stator winding from being detached.

The stator body can be made in one piece or in several pieces.

A one-piece stator body is characterized in that the entire stator body is formed in one piece, viewed circumferentially. The stator body is generally formed from a large number of stacked, laminated electrical laminations, with each of the electrical laminations being closed to form a circular ring.

A segmented stator body is characterized in that it is made up of individual stator segment parts. The stator body can be made up of individual stator teeth or stator tooth groups, with each individual stator tooth or each individual stator tooth group being formed from a large number of stacked, laminated electrical laminations, with each of the electrical laminations being designed as a stator segment sheet metal part.

A rotor is the spinning (rotating) part of an electrical machine. In particular, one speaks of a rotor when there is also a stator.

In the context of the invention, a rotor body is understood to mean the rotor without a rotor shaft. The rotor body is composed in particular of the laminated rotor core and the magnetic elements introduced into the pockets of the laminated rotor core or fixed circumferentially to the laminated rotor core and any axial cover parts present for closing the pockets and the like.

A laminated rotor core is understood to be a plurality of laminated individual laminations or rotor laminations, which are generally made of electrical steel sheet and are stacked and packaged one on top of the other to form a stack, the so-called laminated rotor core.

The invention will be explained in more detail below with reference to figures without restricting the general inventive idea.

• 1 ein Ablaufdiagram für ein Verfahren zum Paketieren von Elektroblechen,
• 2 ein Kraftfahrzeug mit einem vollelektrischen und einem hybriden Antriebsstrang,

Show it:

• 1 a flowchart for a process for packaging electrical steel sheets,
• 2 a motor vehicle with an all-electric and a hybrid powertrain,

the 1 shows a schematic flowchart of a method for packaging electrical steel sheets 1, in particular for use in electrical machines 2 in hybrid or all-electric drive trains 3 of motor vehicles 4, as an example in FIG 2 is shown.

1. (A) Bereitstellen eines Elektroblechs 1,
2. (B) Bereitstellen eines fließfähigen Haftklebstoffs 5,
3. (C) Beschichtung wenigstens einer ersten Blechseite 6 des Elektroblechs 1 mit dem Haftklebstoff 5 bei einer Temperatur des Elektroblechs 1 zwischen 10°C-80°C, bevorzugt 10°C-45°, insbesondere bevorzugt bei Raumtemperatur,
4. (D) Zusammenfügen einer Mehrzahl der Elektrobleche 1 zum Verbinden dieser über den Haftklebstoff 5 bei einer Temperatur der Elektrobleche 1 zwischen 10°C-80°C, bevorzugt 10°C-45°, insbesondere bevorzugt bei Raumtemperatur,
5. (E) Verpressen der Elektrobleche 1 zu einem Elektroblechpaket 7 bei einer Temperatur zwischen 10°C-80°C, bevorzugt 10°C-45°, insbesondere bevorzugt bei Raumtemperatur.

The procedure in the 1 includes the following steps:

1. (A) providing an electrical steel sheet 1,
2. (B) providing a free-flowing pressure-sensitive adhesive 5,
3. (C) Coating of at least a first metal sheet side 6 of the electrical steel sheet 1 with the pressure-sensitive adhesive 5 at a temperature of the electrical steel sheet 1 between 10° C.-80° C., preferably 10° C.-45° C., particularly preferably at room temperature,
4. (D) joining together a plurality of the electrical sheets 1 to connect them via the pressure-sensitive adhesive 5 at a temperature of the electrical sheets 1 between 10° C.-80° C., preferably 10° C.-45°, particularly preferably at room temperature,
5. (E) Pressing the electrical laminations 1 to form an electrical laminations 7 at a temperature between 10° C.-80° C., preferably 10° C.-45°, particularly preferably at room temperature.

The pressure-sensitive adhesive 5 used in process steps (A)-(E) contains a polyvinyl butyral and has a viscosity of 0.2-100 mPa*sec at room temperature.

The coating applied in process step (C) using the pressure-sensitive adhesive 5 has an average layer thickness of 1-20 μm, preferably 2-7 μm.

The pressure-sensitive adhesive 5 can be applied to at least the first metal sheet side 6 of the electrical steel sheet 1 by means of a spraying method, a printing method or a rolling or brushing method. In particular, it is possible for the pressure-sensitive adhesive 5 to be applied before and/or in a tool in the direction of gravity and/or counter to the direction of gravity.

After the electrical steel sheet 1 coated with pressure-sensitive adhesive 5 has been punched out—which can take place between method steps (C) and (D)—this is held in the tool die of the punching tool, so that the next electrical steel sheet 1 is pressed onto the electrical steel sheet clamped underneath during punching. Due to this joining force, the two electrical steel sheets 1 stick together and have a handling strength that is sufficient for the further work steps. The laminated core 7 manufactured in this way is passed on to the subsequent processes.

The pressing of the electrical laminations 1 to form an electrical laminations 7 in process step (E) can take place at pressures between 0.5-5 MPa.

The pressing lasts between 1/60-1/800 min, preferably 1/200-1/600 min, particularly preferably 1/150-1/400 min.

The laminated cores 7 resulting from the method described can be used in particular for an electric machine 2, in particular for use in hybrid or fully electric drive trains 3 of motor vehicles 4. The electrical machine 2 comprises a stator and a rotor, the stator having the stacked electrical lamination stack 7 with a plurality of electrical lamination sheets 1, at least one of the opposing electrical lamination stacks 1 having a coating with a pressure-sensitive adhesive 5 and/or the rotor having a stacked electrical lamination stack 7 having a plurality of electrical laminations 1, wherein at least one of opposite electrical laminations 1 has a coating with a pressure-sensitive adhesive 5.

The invention is not limited to the embodiments shown in the figures. The foregoing description is therefore not to be considered as limiting but as illustrative. The following patent claims are to be understood in such a way that a mentioned feature is present in at least one embodiment of the invention. This does not exclude the presence of other features. If the patent claims and the above description define 'first' and 'second' feature, this designation serves to distinguish between two similar features without establishing a ranking.

Reference List

1

electrical sheets

2

electric machine

3

powertrain

4

motor vehicle

5

pressure sensitive adhesive

6

sheet metal side

7

electrical laminated core

Claims (12)

Method for stacking electrical sheets (1), in particular for use in electrical machines (2) in hybrid or all-electric drive trains (3) of motor vehicles (4), comprising the following steps: • Providing an electrical sheet (1), • providing a free-flowing pressure-sensitive adhesive (5), • Coating of at least a first sheet metal side (6) of the electrical steel sheet (1) with the pressure-sensitive adhesive (5) at a temperature of the electrical steel sheet (1) between 10° C.-80° C., preferably 10° C.-45° C., particularly preferably at room temperature, • Assembling the electrical steel sheets (1) to connect them via the pressure-sensitive adhesive (5) at a temperature of the electrical steel sheets (1) between 10° C.-80° C., preferably 10° C.-45° C., particularly preferably at room temperature, • Pressing the electrical laminations (1) to form an electrical laminations (7) at a temperature between 10° C.-80° C., preferably 10° C.-45°, particularly preferably at room temperature. procedure after claim 1 , characterized in that the pressure-sensitive adhesive (5) is essentially free of solvent. Method according to one of the preceding claims, characterized in that the pressure-sensitive adhesive (5) contains a polyvinyl butyral. Method according to one of the preceding claims, characterized in that the pressure-sensitive adhesive (5) has a viscosity of 0.2 - 100 mPa*sec at room temperature. Method according to one of the preceding claims, characterized in that the pressure-sensitive adhesive (5) has a glass transition temperature of <-10°C. Method according to one of the preceding claims, characterized in that the coating by means of the pressure-sensitive adhesive (5) has an average layer thickness of 1-20 µm, preferably 2-7 µm. Method according to one of the preceding claims, characterized in that the pressure-sensitive adhesive (5) is applied at least in sections to at least the first metal sheet side (6) of the electrical steel sheet (1) by means of a spraying process. Method according to one of the preceding claims, characterized in that the pressure-sensitive adhesive (5) is applied at least in sections to at least the first metal sheet side (6) of the electrical steel sheet (1) by means of a printing process. Method according to one of the preceding claims, characterized in that the pressure-sensitive adhesive (5) is applied at least in sections to at least the first sheet metal side (6) of the electrical steel sheet (1) by means of a rolling or brushing method. Method according to one of the preceding claims, characterized in that the pressing of the electrical laminations (1) to form an electrical laminations (7) takes place at pressures of between 0.5-5 MPa bar. Method according to one of the preceding claims, characterized in that the pressing between 1/60-1/800 min, preferred 1/200-1/600 min, particularly preferably 1/150-1/400 min. Electrical machine (2), in particular for use in hybrid or all-electric drive trains (3) of motor vehicles (4), comprising a stator and a rotor, characterized in that the stator has a packetized laminated core (7) with a plurality of laminated cores (1st ), wherein at least one of the opposing electrical laminations (1) has a coating with a pressure-sensitive adhesive (5) and/or the rotor has a stacked electrical laminations (7) with a plurality of electrical laminations (1), with at least one of the opposing electrical laminations (1) has a coating with a pressure-sensitive adhesive (5).

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