DE102022207116A1 - Sheet metal package for an electric machine and method for joining sheet metal lamellas to a sheet metal package - Google Patents

Abstract

The present invention relates to a sheet metal stack (100) for an electric machine, comprising a plurality of sheet metal lamellas along a stacking direction (102), the sheet metal lamellas being welded together in the stacking direction by means of X-shaped weld seams (104).

Description

The present invention relates to laminated cores for electrical machines (electric machines) and in particular to a joining concept for a plurality of laminated metal lamellas to form a laminated core.

The power-generating components of an electric machine, i.e. rotor and stator, are usually assembled from sheet metal packages. Compared to a solid material construction, laminated cores have the advantage that they prevent eddy currents and can thus increase efficiency. When assembling the sheets into packages, it is important to avoid short circuits. The individual sheets or sheet metal lamellas are therefore usually coated with an insulator. They can be made from electrical steel. These can be sheets made of a steel containing silicon, which has improved magnetic properties. The sheet metal stacks are manufactured in several steps: cutting out the sheets, stacking them, permanently joining them and reworking them.

Various technical solutions are known from the prior art for assembling a laminated core. After the individual sheets have been stacked to form a sheet metal package, they can be assembled into a package using either (stamping) packaging, clamps, screws, rivets, baking varnish (over the entire surface), spot or full-surface gluing, or welding.

Using baking varnish to join the sheet metal stacks has proven to be a good, but cost-intensive solution. The full-surface baking varnish process can produce a very homogeneously rigid sheet metal package. However, this rigidity can lead to acoustic abnormalities in the overall assembly (connection of the electric motor to the transmission housing) (e.g. resonance-sensitive vibration amplitudes, etc.)

It is also known to weld sheet metal packages. During welding, the sheets aligned in a sheet stack are typically pressed together in the axial direction and connected by laser welding or by another suitable welding method, with one or more welds being placed along the outer edges of the sheet stack. Fusion welding processes are preferably used, in which the base material of the sheets is melted. The welded connection produced in this way connects the sheet metal lamellas firmly together. Packages that come with, for example, in the US2018269731 , JP2017108578 , US2011248596 The weld seam formations already described are generally resistant to shear and deformation. This elasticity (softness) can occur to a greater extent in assembled stators (ZSB stators, stator laminated cores), which are mounted directly into a gearbox housing without an additional stator carrier, fixed and then screwed several times.

A shear-resistant configuration is also necessary to ensure stabilization in mounting holes for screwing into the gearbox housing. If this is not the case, these and possibly other fixing and mounting holes could not align with one another, making assembly of the ZSB stator into the housing more difficult and leading to air gap inhomogeneities due to, for example, local deformations.

In addition, due to the lack of a shape-stabilizing stator carrier, there is no additional support for the laminated core. There is no surrounding support surface, so the load on the laminated core is higher and it can fan out.

One object of the present invention is to provide a joining process for laminated cores, which forms a dimensionally stable laminated core, for example in the case of stators with direct fastening (for example screwing) into a gearbox housing.

The task is solved by devices and methods according to the independent patent claims. Advantageous further training is the subject of the dependent claims.

According to a first aspect of the present invention, a laminated core for an electric machine is proposed. The laminated core comprises a plurality of laminated metal lamellas along a stacking direction. The sheet metal slats are welded together in the stacking direction using X-shaped weld seams. Studies have shown that an X-arrangement of weld seams can meet the desired requirements for stiffness and dimensional stability of the laminated core. The X-weld seam arrangement allows twice as many weld seams to form force-resulting force components over the same arc length or in a laminated core sector.

In the present case, “along the stacking direction” means that the weld seams have a directional component corresponding to the stacking direction and thus extend over the laminated core in or along the stacking direction. The X-shaped weld seams each also have a further directional component perpendicular to the stacking direction (for example circumferential direction), so that the weld seams are oblique to the stacking direction extend. “X-shaped” in this case means that two weld seams cross each other in an X-shape along the stacking direction at an intersection point, i.e. each weld seam forms an X-strand.

According to some exemplary embodiments, an angle between an axial end face of the laminated core and an X-strand (weld seam) of the X-shaped weld seams is in the range of 30 to 60 °. It has been shown that the optimal angle between the axial end face of the laminated core and each

According to some exemplary embodiments, each X-strand (weld seam) of the X-shaped weld seams extends over an entire axial length of the laminated core. This means that each X-strand (weld seam) can be welded completely in the axial direction over the entire height or length of the laminated core, so that the two weld seams of an

According to some exemplary embodiments, the X-shaped weld seams are located on a radial outer circumference (on a lateral surface) of the laminated core. Access is particularly easy there after the sheet metal slats have been stacked.

According to some exemplary embodiments, two X-shaped weld seams form an X-shaped weld seam pair. The sheet metal lamellae of the sheet metal stack can be welded together in the stacking direction using several pairs of weld seams. This results in so-called XX or multi-X arrangements for dimensional stability and rigidity.

According to some exemplary embodiments, the X-shaped weld seam pairs are arranged evenly distributed in the circumferential direction over an outer circumference of the laminated core. The laminated core can have a plurality of outer circumferential regions in the circumferential direction, with adjacent outer circumferential regions being separated by fastening tabs and/or punched packet studs distributed evenly over the outer circumference. Each outer peripheral area can have at least one X-shaped pair of weld seams (X arrangement). According to some exemplary embodiments, each outer peripheral region has at least two pairs of X-shaped weld seams that are adjacent in circumferential view (XX arrangement).

The fastening tabs and/or punching stacking knobs can therefore be positioned on the outer circumference of the laminated core between two adjacent X or XX arrangements. Due to plasticization effects, this decoupling can reduce springback of individual slat areas in the area of the weld seams and thus increase the surface pressure between the insulating varnish-coated slats. A variant of this would be to position the stamping package studs in the circumferential direction so that they overlap the node or intersection area of an X-weld seam.

Some embodiments also provide weld seam combinations of multi-X weld seams together with intermediate weld seam designs (e.g. single or multi-row, alternating). In a circumferential view, at least one axially extending weld seam can additionally be arranged between adjacent X-shaped pairs of weld seams.

According to some exemplary embodiments, the laminated core has thicker end disks at both axial ends compared to the laminated metal lamellas, which are welded to the laminated metal lamellas by means of the X-shaped weld seams. This can have the advantage that, in addition to the possibility of increasing the stacking factor due to higher preload forces, waviness of the slats on both end sides can also be reduced at the same time.

According to a further aspect of the present invention, a method for joining or connecting sheet metal lamellas to form a sheet metal package is proposed.

The method includes arranging a plurality of sheet metal lamellas along a stacking direction and welding the sheet metal lamellas using X-shaped weld seams. The welding can include applying the X-shaped weld seams to an outer circumference of the laminated core.

Individual embodiments of the present invention are described below using the figures as examples.

• 1 ein erstes Ausführungsbeispiel eines Blechpakets mit am Außenumfang X-förmig verschweißten Blechlamellen;
• 2 ein zweites Ausführungsbeispiel eines Blechpakets mit am Außenumfang X-förmig verschweißten Blechlamellen;
• 3 ein drittes Ausführungsbeispiel eines Blechpakets mit am Außenumfang X-förmig verschweißten Blechlamellen;
• 4 ein viertes Ausführungsbeispiel eines Blechpakets mit am Außenumfang X-förmig verschweißten Blechlamellen;
• 5 ein fünftes Ausführungsbeispiel eines Blechpakets mit am Außenumfang X-förmig verschweißten Blechlamellen;
• 6 ein sechstes Ausführungsbeispiel eines Blechpakets mit am Außenumfang X-förmig verschweißten Blechlamellen;
• 7 ein siebtes Ausführungsbeispiel eines Blechpakets mit am Außenumfang X-förmig verschweißten Blechlamellen;
• 8 ein achtes Ausführungsbeispiel eines Blechpakets mit am Außenumfang X-förmig verschweißten Blechlamellen;
• 9 ein neuntes Ausführungsbeispiel eines Blechpakets mit am Außenumfang X-förmig verschweißten Blechlamellen;
• 10 ein zehntes Ausführungsbeispiel eines Blechpakets mit am Außenumfang X-förmig verschweißten Blechlamellen;
• 11 ein elftes Ausführungsbeispiel eines Blechpakets mit am Außenumfang X-förmig verschweißten Blechlamellen; und
• 12 ein zwölftes Ausführungsbeispiel eines Blechpakets mit am Außenumfang X-förmig verschweißten Blechlamellen.

Show it:

• 1 a first exemplary embodiment of a laminated core with metal lamellas welded in an X shape on the outer circumference;
• 2 a second exemplary embodiment of a laminated core with sheet metal lamellas welded in an X shape on the outer circumference;
• 3 a third exemplary embodiment of a laminated core with sheet metal lamellas welded in an X shape on the outer circumference;
• 4 a fourth exemplary embodiment of a laminated core with sheet metal lamellas welded in an X shape on the outer circumference;
• 5 a fifth exemplary embodiment of a laminated core with sheet metal lamellas welded in an X shape on the outer circumference;
• 6 a sixth exemplary embodiment of a laminated core with sheet metal lamellas welded in an X shape on the outer circumference;
• 7 a seventh embodiment of a laminated core with sheet metal lamellas welded in an X-shape on the outer circumference;
• 8th an eighth embodiment of a laminated core with sheet metal lamellas welded in an X shape on the outer circumference;
• 9 a ninth exemplary embodiment of a laminated core with sheet metal lamellas welded in an X shape on the outer circumference;
• 10 a tenth exemplary embodiment of a laminated core with sheet metal lamellas welded in an X shape on the outer circumference;
• 11 an eleventh exemplary embodiment of a laminated core with sheet metal lamellas welded in an X shape on the outer circumference; and
• 12 a twelfth exemplary embodiment of a laminated core with sheet metal lamellas welded in an X shape on the outer circumference.

The 1 shows a schematic top view of a substantially ring-shaped laminated core 100 for an electric machine. The laminated core 100 is a stator laminated core. However, it will be clear to a person skilled in the art that the inventive concept presented here can in principle also be applied to rotor lamination stacks for electric machines. The electric machine can be, for example, an asynchronous machine or a synchronous machine.

The laminated core 100 is formed by stacking a plurality of sheet metal lamellas (electrical sheets) along a stacking direction 102, each of which can be obtained by punching out a desired shape from a steel sheet starting material. The sheet metal slats are not explicitly shown individually in the figure. The stacking direction 102 is also referred to as the axial direction because it corresponds to a stator or rotor axis. A material of the sheet metal slats can be, for example, silicon steel or Armco iron. Each of the plurality of sheet metal slats can be covered with an insulating coating so that adjacent sheet metal slats are insulated from one another when the plurality of sheet metal slats are stacked. The sheet materials can be uncoated or coated on one/two sides and/or made of different material types/types of steel (e.g. additional end/balancing disks or cooling baffles, etc.).

Like it in 1 can be seen schematically, the stacked annular sheet metal lamellas are welded together in the stacking direction 102 by means of X-shaped weld seams 104 to form the sheet metal stack 100. “X-shaped” here means that the weld seams 104 each run obliquely to the stacking direction 102 (axial direction) and cross each other at a weld seam intersection 106. The welds 104 of the 1 So have directional components n stacking direction 102 and in the circumferential direction (tangential direction). In the exemplary embodiment shown, the weld seam crossing 106 is located axially in the middle of the laminated core 100. However, weld seam crossings outside the axial center are also possible (see 8-12 ). An X arrangement of welds thus includes a first oblique weld 104-1 that forms a first 106 crosses. The welds 104-1, 104-2 form an x-shaped pair of welds. The weld seams 104 can each extend over the entire axial length of the laminated core 100 in order to connect all of the laminated metal lamellas to one another.

• • Laserschweißen
• • Metall-Aktivgasschweißen
• • Wolfram-Inert-Gasschweißen
• • Lichtbogen-Handschweißen
• • Widerstands-Punktschweißen.

The following exemplary welding processes can be considered for sheet metal stack production:

• • Laser welding
• • Metal active gas welding
• • Tungsten inert gas welding
• • Manual arc welding
• • Resistance spot welding.

In the exemplary embodiment shown, the 0) can be produced.

It is also conceivable that the weld seams run on a radial inside (inner circumference), or on side surfaces of radially inwardly projecting teeth for windings of the laminated core.

An angle α between an axial end face 108 of the laminated core 100 and an X-strand of the X-shaped weld seams 104 is advantageously in a range of 30° to 60°. The respective angles of the two X-strands 104-1, 104-2 can be identical in magnitude, which is the case With regard to the axial direction 102, this leads to a symmetrical weld seam arrangement. However, asymmetrical embodiments are also conceivable in which the respective weld seam angles of the two X-strands 104-1, 104-2 are different.

On its outer circumference, the laminated core 100 shown has fastening tabs and/or stamped package studs 110 evenly distributed over the outer circumference. In the exemplary embodiment shown, there are three fastening tabs and/or punching package studs 110 at an angular distance of 120°. The fastening tabs and/or stamping package studs 110 delimit adjacent outer peripheral regions 112-1, 112-2, 112-3 of the laminated core 100. In the exemplary embodiment shown, each outer peripheral region 112-1, 112-2, 112-3 has two X-shaped pairs of weld seams adjacent in the circumferential direction on (XX arrangement), so that there are a total of six X-shaped pairs of weld seams distributed over the outer circumference. One X-shaped weld pair 104-1, 104-2 (X arrangement) per outer peripheral area 112-1, 112-2, 112-3 would also be possible, as would three or more Arrangement).

Between the X-shaped weld seam pairs of an outer peripheral region 112 arranged adjacently in the circumferential direction, as in 1 shown, further weld seams 114 running in the axial direction 102 may be provided, which can take on various shapes. In the 1 and 2 Axial weld seams 114 shown run in two axial rows adjacent in the circumferential direction. While the in 2 axial weld seams 114 shown run continuously between both axial ends of the laminated core 100, which run in 1 axial weld seams 114-1, 114-2 shown are each axially interrupted according to a dashed line. The respective interruptions of the adjacent axially extending weld seams 114-1, 114-2 are at different axial positions (axially offset from one another), so that all sheet metal lamellas are still welded together by the axial weld seams 114-1, 114-2.

At the in 3 and 4 In the exemplary embodiments shown, exactly one axial weld seam 114 runs between the circumferentially adjacent X-shaped weld seam pairs of an outer peripheral region 112. While the in 4 shown axial weld seam 114 runs continuously between both axial ends of the laminated core 100, which runs in 3 shown axial weld seam 114 between both axial ends of the laminated core 100 is axially interrupted according to a dashed line.

In the embodiment of the 5 no additional weld seam is provided between the X-shaped weld seam pairs adjacent in the circumferential direction. In the embodiment of the 6 two adjacent axial weld seams 114-1, 114-2 run in the circumferential direction adjacent to the two X-shaped pairs of weld seams of an outer peripheral region 112. In the embodiment of 7 Only one X-shaped pair of weld seams 104-1, 104-2 is provided per outer peripheral region 112. In the circumferential direction adjacent to this, two interrupted axial weld seams 114-1, 114-2 run in the outer peripheral region 112 according to a dashed line.

With those in the 8th until 12 In the embodiments shown, the weld seam intersections 106 of the X-shaped weld seam pairs are not in the axial center of the laminated core 100, but offset (to the left). This can be achieved by appropriately selected angles α between the axial end face 108 of the laminated core 100 and the X-strands of the X-shaped weld seams 104.

As part of the present invention, a large number of different weld seam designs were tested with regard to dimensional stability and rigidity and compared with the classic baking varnish solution. Arrangements of the weld seams that were already known from the prior art were compared. Another type of weld seam that was included in the investigations is the X or XX design of the weld seam presented here.

The investigations have shown that the X, XX or multi-X arrangement can meet the desired requirements for stiffness and dimensional stability. It is irrelevant whether the weld seam on the laminated core was raised, embedded (recessed) or lying on the periphery of the circle (e.g. outside 0). Weld seam combinations of multi-X weld seams can also be combined and produced together with or without intermediate weld seam designs (e.g. single or multi-row, alternating).

Through various simulations such as modal analyses, natural frequency analyzes and the like, resonance-sensitive vibration amplitudes can be localized for each laminated core design. In these areas, a lower stiffness is sought in order to actively dampen resonance phenomena there. It is therefore suggested to use a specific weld seam arrangement with damping properties at the critical positions (e.g. number and angular shape of the X-strands).

The X-weld seam arrangement allows twice as many weld seams to form force-resulting force components over the same arc length or in a laminated core sector. It has been shown that the optimal weld seam angle between the axial end face of the core and each

Each

Furthermore, thicker end disks could be provided on the two end sides and welded together with the functional slats. This has the advantage that, in addition to the possibility of increasing the stacking factor due to higher preload forces, the waviness of the slats on both end sides can also be reduced at the same time.

A laminated core according to the invention can be pre-fixed at several points evenly distributed over the circumference using punched core connections.

The laminated core can also have fastening tabs distributed over the circumference, which are used for later screwing to a transmission housing. In the area of the screw tabs, additional punching stacking links can be positioned, the geometric extension direction of which differs by 90° from the other flow-optimized and tangentially aligned punching stackings and thus additionally improve the tangential shear stiffness of the laminated core over the entire height.

With regard to the proposed X-shaped design of the weld seams, it is also recommended to position the punch package between two adjacent XX arrangements. Due to plasticization effects, this decoupling can reduce springback of the individual lamella areas in the area of the weld seams and thus increase the surface pressure between the lamellae coated with insulating paint. A variant of this is to position the punch package overlapping the node area of an X-seam.

In order to ensure not only high rigidity of the laminated core, it is suggested to position the Multi-X welds near the fastening and fixing tabs. Since the requirements for stabilization are greatest here and the holes can therefore be made more aligned and stable.

Furthermore, the following claims are hereby incorporated into the detailed description, whereby each claim may stand on its own as a separate example. While each claim can stand on its own as a separate example, it should be noted that - although a dependent claim may refer to a particular combination with one or more other claims in the claims - other examples also include a combination of the dependent claim with the subject matter of each may include other dependent or independent claims. Such combinations are explicitly suggested here, unless it is stated that a particular combination is not intended. Furthermore, features of a claim should also be included for any other independent claim, even if that claim is not made directly dependent on the independent claim.

Reference symbols

100

Sheet metal package

102

Stacking direction

104

X strand of an X-shaped weld

106

Weld crossing

108

front side

110

Fastening tabs

112

Outer perimeter area

114

axially running weld seam

QUOTES INCLUDED IN THE DESCRIPTION

This list of 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.

Cited patent literature

• US 2018269731 [0005]
• JP 2017108578 [0005]
• US 2011248596 [0005]

Claims (12)

A sheet metal stack (100) for an electric machine, comprising a plurality of sheet metal lamellas along a stacking direction (102), the sheet metal lamellas being welded together in the stacking direction by means of X-shaped weld seams (104). Sheet metal package (100). Claim 1 , wherein a weld seam angle between an axial end face (108) of the laminated core (100) and an X-strand of the X-shaped weld seams (104) is in the range of 30 ° to 60 °. Laminated core (100) according to one of the preceding claims, wherein each X-strand of the X-shaped weld seams (104) extends over an entire axial length of the laminated core (100). Sheet metal package (100) according to one of the preceding claims, wherein the X-shaped weld seams (104) are located on an outer circumference of the sheet metal package (100). Sheet metal package (100) according to one of the preceding claims, wherein two X-shaped weld seams (104-1; 104-2) form an 2) are welded together. Sheet metal package (100). Claim 5 , wherein the weld seam pairs (104-1; 104-2) are arranged distributed in the circumferential direction on an outer circumference of the laminated core (100). Sheet metal package (100). Claim 5 or 6 , wherein the laminated core has a plurality of outer circumferential regions (112) in the circumferential direction, with adjacent outer circumferential regions (112) being separated by fastening tabs (110) and/or stamped stacking knobs evenly distributed over the outer circumference, and wherein each outer circumferential region (112) has at least one X-shaped pair of weld seams ( 104-1; 104-2). Sheet metal package (100). Claim 7 , wherein each outer peripheral region (112) has at least two X-shaped weld seam pairs (104-1; 104-2) which are adjacent in circumferential viewing. Sheet metal package (100). Claim 8 , wherein at least one axially extending weld seam (114) is arranged circumferentially between the adjacent X-shaped weld seam pairs (104-1; 104-2). Sheet metal package (100) according to one of the preceding claims, wherein the sheet metal package has thicker end disks at both axial ends compared to the sheet metal lamellas, which are welded to the sheet metal lamellas by means of the X-shaped weld seams (104). Method for joining sheet metal lamellas to a laminated core (100), comprising arranging a plurality of sheet metal lamellas along a stacking direction (102); and welding the sheet metal lamellas using X-shaped weld seams (104). Procedure according to Claim 11 , wherein the welding includes applying the X-shaped weld seams (104) to an outer circumference of the laminated core (100).

Images