Laminated core, in particular for stator of electric machine, and method for producing such laminated core

Abstract

The invention relates to a laminated core (3) and to a method for producing a laminated core, in particular for a stator of an electric machine. The laminated core (3) has a plurality of layers (3a, 3b, 3c, 3d) arranged one on top of the other, each layer being formed from a single plate (2) or from a plurality of plates (2a, 2b, 2c) arranged adjacent to one another, and each plate (2, 2a, 2b, 2c) having a projection (9a, 9b), the layers (3a, 3b, 3c, 3d) engaging with one another via the projections (9a, 9b), and the laminated core (3) having a centrally located longitudinal axis (L). In order to be able to withstand high hydraulic pressures, for example as a result of the liquid cooling of the laminated core (3), it is proposed that the projections (9a, 9b) are designed so as to entirely surround the longitudinal axis (L) of the laminated core (3) for the case where a layer (3a, 3b, 3c, 3d) is formed on an individual sheet metal part (2), or that the projections (9a, 9b) are designed so as to entirely surround the longitudinal axis (L) of the laminated core (3) for the case where a plurality of sheet metal parts (2a, 2b, 2c) are arranged adjacent to one another and form layers (3a, 3b, 3c, 3d). The projections of the plates (2a, 2b, 2c) are designed to jointly completely surround the longitudinal axis (L) of the laminated core (3).

Description

Technical Field

[0001] The invention relates to a laminated core, in particular a laminated core for an electric motor stator, and a method for producing such a laminated core, the laminated core having a plurality of layers stacked one on top of another, wherein each layer is formed by a separate sheet metal part or a plurality of sheet metal parts arranged adjacent to one another, and each sheet metal part has projections, via which the layers engage one another, and the longitudinal axis of the laminated core extends through the center of the laminated core. Background Art

[0002] For the lamination stack, the reduction in size and the increase in power density require flushing with coolant - which requires no gaps between the layers of stacked plates. For this purpose, it is known, for example, to use a hot-melt adhesive lacquer layer between the plates to bond the stacked plates together under pressure. However, due to parameter fluctuations in the stacking process for producing the lamination stack, undesirable adverse effects on the performance at the hot-melt adhesive layer cannot be completely avoided or gaps are formed at the lamination stack due to other negative influences - especially when the fluid pressure at the lamination stack is high. Therefore, such lamination stacks are usually not used in high-power areas with strong cooling requirements.

[0003] Furthermore, laminated cores are known (US Pat. No. 4,578,853) in which embossed reliefs are provided on the sheet metal part, by means of which reliefs the relevant layers of the laminated core engage with one another. Summary of the invention

[0004] The object of the present invention is therefore to modify the structure of a laminated core of the type mentioned at the outset so that it can be cooled by a liquid having a high hydraulic pressure and can therefore be used universally.

[0005] The invention solves this problem by the features of claim 1 .

[0006] If the protrusions on a single plate forming a layer are designed to completely surround the longitudinal axis of the laminate stack, the stability of the laminate stack against liquid penetration between the layers can be improved. Alternatively, when multiple plates forming a layer are arranged adjacent to each other, the protrusions of these plates are designed to completely surround the longitudinal axis of the laminate stack together, which can improve the stability of the laminate stack against liquid penetration between the layers.

[0007] These projections, which are designed in both variants to completely surround the longitudinal axis of the lamination stack (e.g. the central longitudinal axis), ensure that there are no gaps in these areas when the plates are stacked. In addition, this forms a barrier between the layers at the lamination stack - this also ensures that the gap-free lamination stack can withstand higher hydraulic pressures, which is necessary for external cooling of the stator lamination stack in the high-performance area.

[0008] Such a projection can also advantageously be produced on the laminated core using known methods, such as are known from crimping, for example.

[0009] Preferably, each layer of the laminated core has a sheet metal element, which always ensures a continuous, completely circumferential projection of the layer, in particular without gaps, compared to segmented layers, i.e. layers formed from a plurality of sheet metal elements arranged adjacent to one another and abutting one another. Thus, the highest pressure resistance can be achieved with laminated cores whose layers consist of a single sheet metal element.

[0010] When using segmented layers, a sealing material, advantageously a resin-based sealing material, may be provided on the abutment surfaces between the plates arranged adjacent to each other, which may, for example, further increase the pressure resistance.

[0011] The laminated core according to the invention is therefore not only robust for liquid cooling and can be universally used even at high hydraulic pressures, but can also be produced inexpensively and reproducibly.

[0012] Preferably, the projections are arranged in the outer third of the lamination stack to be able to withstand high hydraulic pressures, for example when the lamination stack is externally cooled. Thus, the lamination stack according to the invention can be used stably even in high-performance areas with strong cooling requirements.

[0013] This is particularly true when the projections are arranged in the region of the outer periphery of the laminated core, for example by providing a maximum distance of 10 mm between the projections and the outer periphery. This allows the risk of potential influence of the magnetic properties of the laminated core by the projections engaging one another to be kept low.

[0014] The design of the laminated core can be made even easier if the projections are each formed by a step in the sheet metal, and wherein each outer edge of the sheet metal forms a step base of the step.

[0015] Alternatively, it is conceivable that the projections in the plate are each formed by a flange, in particular a circular flange. This can also ensure a sufficiently high barrier effect against liquid penetration - even when relatively high hydraulic pressures are applied.

[0016] It is also conceivable that the protrusions each have a protrusion height in the range of greater than or equal to 0.5 times to less than or equal to 2 times (in particular less than or equal to 1 times) the thickness of the plate. In addition, the protrusions formed in this way can be relatively easily arranged on the plate. The plate can, for example, have a thickness of 0.1 mm to 1 mm (in particular 0.2 mm to 0.5 mm).

[0017] The invention is particularly advantageous in the case where the lamination stack is bonded. The sheet metal parts forming the layer are bonded together by an adhesive layer provided on the sheet metal parts, in particular a heat-curing hot-melt adhesive lacquer (eg baking lacquer). Preferably, the adhesive is provided on the entire surface of the sheet metal parts.

[0018] When the plates are stacked, these projections ensure that the adhesive is under pressure in several directions and not just in the stacking direction - this reliably avoids the formation of air bubbles between the layers. The bonded laminated core is therefore particularly suitable for liquid cooling and ensures high stability even at relatively high hydraulic pressures. Such a laminated core therefore excels, for example, when used in high-performance applications with high cooling requirements.

[0019] The object of the present invention is also to create a method for reproducibly producing a liquid-cooled laminated core.

[0020] The invention solves the stated problem by means of the features of claim 8 .

[0021] By forming the protrusions in the plate or plate-like strip or in the plate parts by forming the plate material and stacking the plate parts so that in the case of a single plate part in the relevant layer, the protrusions on the single plate part are designed to completely surround the longitudinal axis of the laminate stack, or in the case of multiple plates arranged adjacent to each other in the relevant layer, the protrusions on these plate parts together form a complete loop around the longitudinal axis of the laminate stack, a particularly strong barrier to prevent liquid penetration can be repeatedly formed on the laminate stack.

[0022] Furthermore, by means of relatively simple shaping methods known from the crimping process, this method step can be easily provided when stacking the laminated core, which also brings advantages to the method in terms of operation. Thus, by means of the method according to the invention, laminated cores can be produced repeatedly without significant additional effort, which can stably withstand liquid cooling with relatively high hydraulic pressures.

[0023] Preferably, the projections are introduced and the sheet metal parts are stacked such that the projections are arranged in the outer third of the laminated core, so that in particular a barrier is produced which is assigned to the outer shell of the laminated core.

[0024] For example, the arrangement of the projections in the outer peripheral region of the laminated core can further reduce the manufacturing costs in the process, since the projections arranged in the outer peripheral region of the laminated core have a wider size than the projections located inside the laminated core. The reproducibility of the process can be further increased if the projections are at a maximum distance of 10 millimeters from the outer periphery. This is because, when producing projections that engage one another without short circuits, the risk of influencing the magnetic properties of the laminated core due to manufacturing tolerances can be further reduced.

[0025] If the projection is introduced as a step or a ledge, the reproducibility of the process can be further increased.

[0026] The process can be made easier if the outer edge of the plate or plate-like strip or plate part is deep-drawn to form a step.

[0027] The protrusions may be produced in a more reproducible manner by stamping a sheet or plate-like strip or plate to form a flange, in particular a circular flange.

[0028] In order to ensure that the plates are firmly embedded in each other when stacked, it would be advantageous if the protrusions are formed in the plates or plate-like strips respectively and the protrusion height is in the range of greater than or equal to 0.5 times the thickness of the plate to less than or equal to 2 times (especially 1 times) the thickness of the plate.

[0029] By providing a sheet or sheet-like strip with a particularly thermosetting hot-melt adhesive lacquer (especially a baking lacquer), the method enables a liquid-tight laminate stack to be achieved in a particularly reproducible manner, wherein the hot-melt adhesive lacquer is activated and thereby the layers consisting of the sheet parts are connected together in a material-fitting manner.

[0030] Preferably, the sheet or sheet-like strip is provided with a hot-melt adhesive lacquer, in particular a thermosetting one, in particular a baking varnish, the adhesive layer being provided on both flat sides of the sheet or sheet-like strip. Preferably, the hot-melt adhesive lacquer or adhesive layer is provided over the entire surface of the sheet. Preferably, the hot-melt adhesive lacquer is activated when the sheets are stacked and the layers consisting of the sheets are connected together in a material-fitting manner, in order to further accelerate the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The subject matter of the invention is illustrated in more detail, for example, by means of several embodiment variants in the drawings.

[0032] in:

[0033] Figure 1 shows a schematic diagram of an apparatus for producing a lamination stack,

[0034] Figure 2a Shown according to Figure 1 Enlarged partial view of the produced lamination stack,

[0035] Figure 2b shows an enlarged partial view of a lamination stack according to a second embodiment,

[0036] Figure 3a Shown according to Figure 2a A top view of the lamination stack.

[0037] Figure 3bA plan view of a laminated core segmented in layers (ie in the case of a plurality of sheet metal elements arranged next to one another forming a layer) according to a third embodiment is shown. DETAILED DESCRIPTION

[0038] according to Figure 1 , schematically shows an apparatus 1 for carrying out the method according to the invention. The apparatus 1 is used to stack punched sheet metal parts 2 to form a laminated core 3. For this purpose, a sheet-like strip 5, i.e. an electrical steel strip (or in the case of sheet metal, an electrical steel sheet), is unwound from a coil 4, which sheet-like strip 5 has a full-surface adhesive layer 8, i.e. a thermosetting hot-melt adhesive layer, such as a baking varnish, on one of the two flat sides 6, 7. It is conceivable that a full-surface adhesive layer 8, i.e. a thermosetting hot-melt adhesive layer, such as a baking varnish, is applied to both flat sides 6 and 7 - but this is not shown in the figure.

[0039] The plate-shaped strip 5 has a strip thickness or thickness d of 0.3 mm (millimeters).

[0040] By means of a punching tool 11, in this embodiment a sequential punching tool, a plurality of sheet metal parts 2 are separated, more specifically punched out, from the sheet-like strip 5 coated with adhesive. As generally mentioned, this punching out can be cutting, severing, shearing, trimming, splitting by pressing, etc.

[0041] from Figure 1 As can be seen in FIG, the punching tool 11 cuts with a plurality of strokes 12. To this end, the cutting tools 13a, 13b in the upper tool 11a of the punching tool 11 cooperate with the corresponding dies 14a, 14b of the lower tool 11b of the punching tool 11, thereby forming two punching stages 15a, 15b in the punching tool 11.

[0042] By means of the first cutting tool 13a of the upper tool 11a, a notch 16 is formed (i.e. punched out) in the plate-like strip 5, which can be obtained from Figure 1 The punched out residual part 17 can be seen in FIG.

[0043] The plate member 2 is separated from the plate-like strip 5 by means of the cutting tool 13 b.

[0044] A notch 16 is provided in the plate-shaped strip 5 for each separated sheet metal part 2, and the notch thus passes through the laminated core 3 as a receptacle 18 in the laminated core 3 (centrally in the present embodiment). The receptacle 18 is provided for receiving a portion of the electric machine 100 which is implicitly located in the laminated core 3. Figure 3a 1 and 2. The rotor R shown in FIG. 2 is opposite to the rotor R, in which the laminated core 3 is used as a stator.

[0045] Then, the sheet metal part 2 is punched out using the punching stage 15b, and the sheet metal part 2 is pressed into the stacking device 19 by the pressure of the upper tool 11a and stacked there. For this purpose, the stacking device 19 has a guide located in the lower tool 11b. The guide also provides Figure 1 The reaction holder 10 is partially shown in FIG.

[0046] The stacking device 19 is actively heated in order to activate the hot-melt adhesive layer of the plate elements 2 and to produce an adhesive or material-bonded connection between the plate elements 2. The laminated core 3 is laminated in this way.

[0047] In order to form a medium-tight lamination stack 3, projections 9a, 9b are formed in the sheet metal strip 3 by sheet metal forming. These projections 9a, 9b are stamped in the forming stage 21 using a punch 23a and a die 23b. Each plate 2 of the laminated core 3 has such protrusions 9a, 9b. The separated plate elements 2 are then stacked to form a laminated core 3 having a plurality of layers 3a, 3b, 3c, 3d, so that the plurality of layers 3a, 3b, 3c, 3d of the laminated core 3 are mutually engaged through the protrusions 9a, 9b of the plate elements 2 - as in particular in Figure 2a and Figure 2b Here it can be seen how each protrusion 9a, 9b on a plate 2 engages in a recess on an adjacent plate 2, preferably complementary thereto.

[0048] According to the invention, these projections 9a, 9b are specially designed - more specifically, the projections 9a, 9b are designed to completely surround the longitudinal axis L of the lamination stack 3 - as shown in Figure 2a , Figure 2b , Figure 3a and Figure 3b For this, see Figure 1 , Figure 2a and Figure 2b The layers 3a, 3b, 3c, 3d each have a separate plate 2. In the exemplary embodiment, the longitudinal axis L is the central longitudinal axis of the lamination stack 3, ie the longitudinal axis L extending through the center of the lamination stack 2. In the exemplary embodiment, this longitudinal axis L is also, for example, the axis of symmetry of the lamination stack.

[0049] If a plurality of plates 2a, 2b, 2c arranged adjacent to each other are provided to form a layer 3a, 3b, 3c, 3d, such as Figure 3b As shown in the figure with three plates 2a, 2b, 2c, the projections of these plates 2a, 2b, 2c together form the longitudinal axis L of the lamination stack 3 in a completely circumferential manner. In addition, a resin-based sealing material 24 is provided on the abutment surfaces between the plates 2a, 2b and 2c, which ensures a liquid-tight connection between the plates 2a, 2b and 2c.

[0050] The completely circumferential projections 9a, 9b in both embodiment variants and the interengagement of the layers 3a, 3b, 3c, 3d form a barrier that prevents the passage of liquid. As a result, the laminated core 3 can be stably cooled by liquid with relatively high hydraulic pressure (for example, using water). This makes the laminated core 3 particularly suitable for use as a stator, especially when small dimensions and high electrical power are required for the electric machine.

[0051] Since the projections 9a, 9b extend in the peripheral U region of the lamination stack 3, the lamination stack 3 is also particularly suitable for liquid cooling at the outer shell of the lamination stack 3. Figure 2a As shown, Figure 2a The distance A between the protrusion 9a and the outer peripheral edge U of the lamination stack 3 is at most 10 mm, and Figure 2b The protrusion 9b forms the outer edge of the plate 2.

[0052] from Figure 2a and Figure 2b It can also be seen that the projections 9a, 9b can be designed differently.

[0053] according to Figure 2a The first protrusion 9a is designed as a flange 21, i.e. a circular flange as shown in the figure. The characteristic of this circular flange is that (compared with a box-shaped flange, a trapezoidal flange, etc.) it can apply pressure to the adhesive between the panels 2 more evenly when stacked.

[0054] according to Figure 2b , showing a second protrusion 9a, the second protrusion 9a is designed as a step portion 22, and the step base 22a of the step portion 22 corresponds to the outer edge of the layers 3a, 3b, 3c, 3d.

[0055] The structural design of the projections 9a, 9b has proven to be sufficient if the projections 9a, 9b each have a projection height h which is substantially equal to the thickness d of the sheet metal 2. In this case, the sheet metal 2 is at most engaged in the adjacent sheet metal 2 - this simplifies not only the lamination stack 3 but also the stacking process.

[0056] Figure 3a An electric motor 100 is also schematically shown. The electric motor has a stator with a laminated core 3 according to the invention, which has a radius r. In addition, the electric motor 100 is equipped with a cooling device 25, which guides a cooling liquid 26. The cooling device 25 applies the cooling liquid 26 directly to the outer shell M of the laminated core 3, so that it comes into contact with the layers 3a, 3b, 3c and 3d of the laminated core. The laminated core 2, which is dense due to the surrounding protrusions 9a, 9b, can withstand even high hydraulic pressure liquid cooling, thus allowing a high power density to be achieved with a small-sized electric motor 100.

[0057] Generally, it is noted that "particularly" can be translated into English as "more particularly". Features beginning with "particularly" should be considered as optional features that can be omitted, and therefore do not represent limitations on the claims, for example. The same applies to "preferably", which is translated into English as "preferably".

Claims

1. A laminated core, in particular for a stator of an electric motor, the laminated core having a plurality of layers (3a, 3b, 3c, 3d) arranged one above the other, wherein: Each layer is formed by a single plate (2) or by a plurality of plates (2a, 2b, 2c) arranged adjacent to each other, and each plate (2, 2a, 2b, 2c) has a projection (9a, 9b), the layers (3a, 3b, 3c, 3d) are mutually engaged via the projections (9a, 9b), and the laminated core (3) has a longitudinal axis (L) extending through the center of the laminated core (3), the laminated core being characterized in that: In the case of a single sheet (2) forming a layer (3a, 3b, 3c, 3d), the projections (9a, 9b) are designed to completely surround the longitudinal axis (L) of the lamination stack (3), or In the case where a plurality of plates (2a, 2b, 2c) are arranged adjacent to each other and form a layer (3a, 3b, 3c, 3d), the projections of the plates (2a, 2b, 2c) are designed to completely surround the longitudinal axis (L) of the lamination stack (3) together.

2. The lamination stack according to claim 1, characterized in that: The projections (9a, 9b) are arranged in the outer third of the laminated core.

3. The lamination stack according to claim 2, characterized in that: The projections (9a, 9b) are arranged in the region of an outer periphery (U) of the lamination stack (3), and in particular, the distance between the projections (9a, 9b) and the outer periphery (U) is at most 10 mm.

4. The lamination stack according to any one of claims 1 to 3, characterized in that: The protrusion (9b) is formed by a step portion (22) in each of the plate members (2), and the outer edges of the plate members (2) each form a step base (22a) of the step portion (22).

5. The lamination stack according to any one of claims 1 to 3, characterized in that: The protrusions (9a) are each formed by a flange (21) in the plate (2), and in particular, the flanges (21) are circular flanges.

6. The lamination stack according to any one of claims 1 to 5, characterized in that: Each of the protrusions (9a, 9b) has a protrusion height (h), and the protrusion height (h) is in the range of greater than or equal to 0.5 times the thickness (d) of the plate (2) to less than or equal to 2 times the thickness (d) of the plate (2). In particular, the protrusion height (h) is in the range of greater than or equal to 0.5 times the thickness (d) of the plate (2) to less than or equal to 1 times the thickness (d) of the plate (2).

7. The lamination stack according to any one of claims 1 to 6, characterized in that: The panels (2) forming the layers (3a, 3b, 3c, 3d) are connected to each other in a material-matched manner via an adhesive layer (8) arranged on the panels (2). In particular, the adhesive layer (8) is a thermosetting hot-melt adhesive lacquer, for example, the adhesive layer (8) is a baking lacquer.

8. Method for producing a laminate stack (3) according to any one of claims 1 to 7, wherein: Protrusions (9a, 9b) are formed in a sheet or a sheet-like strip (5) by sheet forming, sheet parts (2) are subsequently separated from the sheet or sheet-like strip (5), wherein a plurality of sheet parts (2) each have at least one protrusion (9a or 9b), and subsequently The separated plate elements (2) are stacked to form a laminated core (3), the laminated core having a plurality of layers (3a, 3b, 3c, 3d), the layers (3a, 3b, 3c, 3d) being stacked one above the other so that the plurality of layers (3a, 3b, 3c, 3d) of the laminated core (3) are engaged with each other via projections (9a, 9b) of the plate elements (2), The method is characterized in that The projections (9a, 9b) are formed in the sheet or sheet-like strip (5) or in the sheet element (2) by sheet forming, and the sheet elements (2) are stacked so that: In the case of a layer (3a, 3b, 3c, 3d) having a single sheet (2), the projections (9a, 9b) are designed to completely surround the longitudinal axis (L) of the lamination stack (3), or In the case of a layer (3a, 3b, 3c, 3d) having a plurality of plates (2a, 2b, 2c) arranged adjacent to one another, the projections of the plates (2a, 2b, 2c) are designed to completely surround the longitudinal axis (L) of the lamination stack (3) together.

9. The method according to claim 8, characterized in that The projections (9a, 9b) are formed and the metal sheets (2) are stacked such that the projections (9a, 9b) are arranged in an outer third of the laminated core.

10. The method according to claim 9, characterized in that The projections (9a, 9b) are arranged in the region of an outer circumference (U) of the laminated core (3), in particular, the projections (9a, 9b) are spaced apart from the outer circumference (U) by a maximum of 10 mm.

11. The method according to any one of claims 8 to 10, characterized in that The protrusions (9a, 9b) are formed as step portions (22) or flanges (21).

12. The method according to claim 11, characterized in that The plate or plate-shaped strip (5) is deep-drawn or the outer edge of the plate member (2) is deep-drawn to form the step portion (22).

13. The method according to claim 11, characterized in that The plate or plate-like strip (5) is molded or the plate member (2) is molded to form the flange (21), in particular, the plate or plate-like strip (5) is molded or the plate member (2) is molded to form a circular flange.

14. The method according to any one of claims 8 to 13, characterized in that Protrusions (9a, 9b) are formed in the plate or plate-like strip (5), wherein each of the protrusions has a protrusion height (h) ranging from greater than or equal to 0.5 times to less than or equal to 2 times the thickness (d) of the plate (2), in particular, the protrusion height (h) ranging from greater than or equal to 0.5 times to less than or equal to 1 times the thickness (d) of the plate (2).

15. The method according to any one of claims 8 to 14, characterized in that The plate or plate-like strip (5) is provided with a hot-melt adhesive lacquer, in particular, the molded or plate-like strip (5) is provided with a thermosetting hot-melt adhesive varnish, in particular, the molded or plate-like strip (5) is provided with a baking varnish, wherein the hot-melt adhesive lacquer is activated, in particular, when the plate parts (2) are stacked, and thus the layers (3a, 3b, 3c, 3d) composed of the plate parts (2) are connected to each other in a material-fitting manner.

16. An electric machine having a stator with a laminated core (3) according to any one of claims 1 to 7, and having a cooling device (26) which guides a cooling liquid (27) which acts directly on the outer shell (M) of the laminated core (3).

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