Laminated core with at least one overmoulded collar

Abstract

The invention relates to a laminated core in the form of a rotor or stator for an electrical machine having a plurality of laminations stacked in the axial direction, wherein the laminated core comprises at least one winding space and at least one overmoulding, wherein the wall of the laminated core has an insulation layer in the direction of each of the winding spaces, wherein at least one overmoulded collar is arranged in each wall of the laminated core in the direction of a winding space and is communicatively operatively connected to the respective insulation layer and the at least one overmoulding, wherein the overmoulded collar is formed by at least one overmoulded collar lamination.

Description

[0001] Disc pack with at least one injection collar

[0002] Description

[0003] The invention relates to a lamination pack designed as a rotor or stator for an electrical machine having a plurality of laminations stacked in the axial direction, wherein the lamination pack comprises at least one winding space and at least one injection molding, wherein the wall of the lamination pack has an insulation layer in the direction of the winding spaces.

[0004] Electrical machines have long been state-of-the-art in a wide range of applications and diverse designs. In addition to the categorization into stationary, i.e., static electrical machines, and rotating, dynamic machines, a multitude of different designs are known within the dynamic category, for example, grouped according to the type of current used, such as direct current, alternating current, and three-phase alternating current, and various winding arrangements for generating a rotating magnetic field. Different operating modes of the machines can be realized using commutator machines, asynchronous machines, and synchronous machines.

[0005] Electrical machines have variously arranged wire coils through which electric current flows. The resulting magnetic flux is guided in a targeted manner within an iron core, also known as a magnetic circuit. This core consists of materials that can conduct magnetic flux well, for example, a plurality of stacked electrical sheets, also known as lamination packs. These stacked or layered lamination packs are used within dynamic electrical machines as stators or rotors, also known as armatures. The stacking, together with the one-sided insulation of the lamination packs, serves to suppress eddy currents.

[0006] In dynamic machines, plate packs, designed as stators or rotors, are primary components and have a significant influence on the machine's properties and efficiency. The magnetic fields generated in electrical machines cause the forces they generate to move the machine parts against each other, usually in a rotational manner. Electrical machines have insulation zones to electrically insulate the current-carrying parts from each other and from the external environment.

[0007] Insulation zones for electrical insulation are required, for example, between the winding zones and the laminar packs. Depending on the design of the laminar packs, such as stators or rotors, insulation is applied using insulating paper, plastic sheathing, or plastic overmolding on the inner surfaces of the laminar packs and on the pole slots. Polymers, for example, are used for insulation zones made of plastic. If the insulation zones are implemented using plastic overmolding, the polymers are preferably injection-moldable thermosets or thermoplastics and form insulation layers in the form of winding supports around the individual laminar pack poles, which serve to accommodate the stator coils or rotor coils.

[0008] The insulation zones of such electrical machines are subject to a number of sometimes contradictory requirements and constraints, as they have a significant impact on the costs and properties of the electrical machines, including the required material usage, installation space requirements, processability, the respective processing method, and material properties. To promote the winding fill ratio of the winding zones in the pole slots on the one hand, and to maximize the material wall thicknesses of the lamination packs to support the required magnetic flux in the lamination packs on the other, it is desirable to minimize the wall thicknesses of the insulation zones. From the perspective of the insulating effect of the insulation zones and implementation within the limits of processing, the insulation wall thicknesses cannot be reduced arbitrarily.

[0009] When manufacturing insulation areas of electrical machines, a common problem associated with plastic injection molding processes, due to the design and geometry, is that the overmolding cannot always be completed completely due to the flow behavior of plasticized plastics and the existing flow gap cross-sections. This can also lead to the formation of cavities in the form of air pockets and / or cold welds (also known as weld lines) in the form of adjacent plastic flow fronts when subjected to high pressure and forced into the flow gaps. This can cause the sheathing to exhibit discontinuities, resulting in insufficient insulation points leading to short circuits.

[0010] To solve the flow gap problem by reducing the flow gap length, i.e., reducing the flow gap distance that the plastic must travel during the injection molding process, DE 10 2017 102 255 A1 proposes segmenting a stator in the axial direction and equipping the stator segments separately with insulation areas. The teaching presented here recognizes the main problem with plastic overmolding of plate packs with a large axial extension as being that long flow paths must be covered in the area of ​​the slots in the overmolding tool during the injection cycle and that greater plastic insulation wall thicknesses are required for the seal feed. This reduces the available winding space and thus the copper filling, resulting in reduced magnetic efficiency of the electrical machine.

[0011] The solution approach of DE 102017 102 255 A1 comprises a plate pack constructed from several individually overmolded plate pack segments, each of which has a shortened axial extension and is modularly assembled to form a complete plate pack. After being separately overmolded, the individual modular plate segment packs are assembled axially in series using connecting elements, preferably integrated into the plate segment packs. In this way, the total flow gap length of the plate pack can be reduced to the axial extension of the plate segment packs, thus reducing the insulation wall thickness.

[0012] Another solution for reducing the flow gap length is proposed by WO 2019 / 120354 A1 in that, in the assembled state of the lamination pack, at least one continuous flow channel running in the axial direction is present in the region of at least one winding space, which is in communication with the plastic layer of the insulating wall and via which the plastic is injected to produce the plastic layer on the inner wall of the winding space.

[0013] This approach is further developed by the teaching of WO 2020 / 083418 A1, which proposes that the injection of at least one axially extending, continuous flow channel in the region of at least one winding space is not located at the end of the plate pack, but rather is arranged centrally or in a central region in the axial direction. In this way, one plane of the injection channels is realized in a central region, with the result that the plasticized plastic flow fronts flow axially in two directions from this plane, and the flow gap length is reduced.

[0014] The solutions available in the state of the art effectively reduce the flow gap length, thus supporting the improvement of the plastic overmolding of plate packs. However, the spreading behavior of the plastic melt within the flow gap remains problematic, as known solutions only reduce the flow gap length, and the plastic melt spreading within the flow gap must flow in both radial and axial directions to fill the flow gap. A multitude of influencing factors and injection molding parameters are relevant here, such as the viscosity of the plastic material, the geometry of the flow gap, the temperature of the plastic melt and the material temperatures adjacent to the flow gap, as well as their thermal conductivity and the plastic flow front velocity.

[0015] The expansion of the plastic melt within the flow gap occurs uncontrolled under the influence of various factors based on pressure distribution and flow resistance in the axial and radial directions starting from the injection point. The direction-dependent flow front velocities and flow front distances develop depending on the geometry and resistance and can hardly be influenced by changes in the injection molding parameters of pressure and temperature relative to each other.

[0016] This can result in discontinuous filling behavior of the plastic melt in some areas, and air pockets and / or weld lines (cold welds) caused by converging flow fronts of the plastic melt can partially impair the insulation effect. Such insulation weaknesses promote breakdowns and increase the risk of ground faults, resulting in electrical machine failure and potentially personal injury.

[0017] The object of the invention is to improve the reliability of the insulation coating of lamination packs of electrical machines produced by overmolding and to at least partially reduce the disadvantages of known solutions.

[0018] To solve this problem, the invention proposes an injection collar extending from at least one injection point, extending in the radial direction of the lamination pack and bordering the winding space defined by the teeth of the lamination pack. The invention recognizes that the injection collar is suitable for significantly increasing the reliability of the insulation coating of lamination packs by ensuring continuous flow of the plastic melt, thus avoiding air pockets and / or weld line formation, thus reducing insulation weak points. To this end, the injection collar guides the plastic melt during the plastic injection molding process in such a way that the previously uncontrolled expansion of the plastic melt is directed into the flow gap.

[0019] Essentially, the injection collar influences the sequence of movements and initially guides the plastic melt largely in a radial direction within the injection collar and then supports the spread of the plastic melt in an axial direction.

[0020] To achieve the objective of the movement sequence consisting of radial plastic melt spread in the injection collar followed by radial plastic melt spread into the flow gap, which forms the insulation sheath of the lamination pack adjacent to the winding space, the invention provides a cross-sectional area of ​​the injection collar that is as small as possible due to installation space constraints, but as large as possible to reduce flow resistance for the required radial plastic melt spread. To ensure the constant and uniform distribution of the plastic insulation material, the required pressure distribution and the flow behavior of the plastic melt can also be influenced by a coordinated area ratio of the injection cross-sectional area and the injection collar cross-sectional area. In principle, it is advantageous if the injection cross-sectional area is larger than or equal to the injection collar cross-sectional area.

[0021] The cross-sectional area ratio of the injection collar and the flow gap of the insulation layer also has a particularly strong influence on the flow direction sequence of the plastic melt in the radial and axial directions. In addition to influencing the flow direction sequence, this also influences the holding pressure time (pressurization of the plastic melt after injection into the cavity) and the solidification behavior of the plastic insulation material, thus further improving homogeneity and reducing the risk of defects in the plastic insulation layer.

[0022] The injection-molded collar according to the invention is preferably designed as a square or rectangular cross-section and represents a section of a flow gap adjacent to a winding space. After the plastic insulation coating has been completed by the plastic injection-molded process, the flow gap, together with the at least one injection-molded collar, forms the insulation coating between the winding in the winding space and the lamination stack region surrounding the winding space.

[0023] Depending on the geometric situation and dimensional conditions, one or more levels of injection molding combined with radially extending injection collars can be provided for the insulation coating of the laminated core adjacent to the winding space. It is also possible to use multiple injection collars starting from a single injection molding and an axially extending injection channel.

[0024] To implement the at least one injection collar, the invention provides that the injection collar lamellae forming these regions have notched areas in the injection collar plane of the lamella pack, which define the injection collar width. The injection collar height is determined by the number of stacked injection collar lamellae with notched areas.

[0025] The invention is explained in more detail below using an exemplary embodiment in conjunction with the figures. In the figures:

[0026] Fig. 1 a perspective partial section of the plate pack with injection collar and

[0027] Fig. 2 a three-dimensional detailed view of the plate pack with injection collar in a sectional view of the injection collar plane and

[0028] Fig. 3 a perspective axial section of the disk pack and

[0029] Fig. 4 a 3D detailed view of the winding space with adjacent insulation layer and abstracted plastic flow fronts and

[0030] Fig. 5 a perspective and abstracted detailed view of the insulation layer adjacent to the winding space and

[0031] Fig. 6 is a plan view of a lamella of the lamella pack for levels outside the injection collar level and Fig. 7 is a plan view of a gating lamella of the lamella pack for the injection level and, or the injection collar level and

[0032] Fig. 8 a plan view of a gate collar lamella of the lamella pack for the gate collar level and

[0033] Fig. 9 a sectional plan view of the plate pack in the injection collar plane and

[0034] Fig. 10 a sectional top view of the plate pack outside the injection collar plane.

[0035] Figure 1 illustrates a perspective partial section of the lamination pack 1 with injection collar 10. The lamination pack 1 is constructed from a plurality of layered laminations 2 outside the plane of the injection collar 10. The injection collar 10 is formed in the injection collar plane of the lamination pack 1 by a plurality of stacked injection collar laminations 11. The partial section shown shows two lamination pack teeth, which together form a winding groove 41 and delimit a winding space 40 (the winding is not shown). Between the wall formed by the lamination pack teeth in the direction of the winding space 40, an electrically non-conductive insulation layer 30' is required, the subsequent wall thickness of which is defined by the flow gap width bf during the injection molding process. This means that the flow gap width bf is not absolutely identical due to the shrinkage of the plastic during cooling, but is approximately equal to the insulation layer width.

[0036] Figure 2 shows a three-dimensional detailed view of the lamination pack 1 with injection collar 10 in a sectional view of the injection collar plane. To construct the injection collar 10, injection collar laminations 11 are used, each of which has a notch area, thus creating space for the injection collar. The notch area defines the injection collar width b and is geometrically designed such that the injection collar 10 is arranged in regions circumferential to the adjacent winding space 40. Channels are connected between the injection collar 10 and the gate 20, allowing plastic melt to flow from the gate 20 into the injection collar 10.

[0037] Figure 3 includes a perspective axial section of the plate pack 1 and shows the radial extension of the injection collar 10 starting from a gate 20. While the injection collar width b is defined by the notch area of ​​the injection collar plate 11, the injection collar height h is determined by the number of injection collar plates 11 used. Thus, the injection collar height h is a multiple of the sheet thickness of a injection collar plate 11 and can be adjusted as desired by the number used.

[0038] Figure 4 shows a 3D detailed view of the winding chamber 40 with the adjacent insulation layer 30' and abstractly depicted plastic flow fronts 31. The individual plastic flow front 31, which flows largely parallel in the axial direction (indicated here by the parallel double arrows), is the result of a largely axial propagation direction with little or no radial propagation movement. This largely axial propagation direction is functionally achieved by the injection collar 10 in that the plastic melt is first introduced into the injection collar 10 via the gate 20 and then spreads radially within the injection collar 10.

[0039] After the injection collar 10 is largely filled with plastic melt, the pressurization of the plastic melt during the injection molding process results in a largely axially directed flow movement of the plastic melt, starting from the injection collar 10 into the flow gap 30, which forms the subsequent insulation layer 30' and defines its insulation layer width. This means that the injection gate 20 and the injection collar 10, as well as the insulation layer 30' formed by the flow gap 30, are in a communicating, operative connection such that a plastic melt introduced under pressure via the injection gate 20 into the injection collar 10 initially largely fills the injection collar volume and then flows into the flow gap 30.

[0040] The injection collar 30 acts on the movement sequence and equalizes the movement directions of the plastic melt away from a combined radial and axial movement direction towards a largely directed spreading behavior, first in the radial direction within the injection collar 10 and then in the axial direction within the flow gap 30.

[0041] This functional effect of the invention utilizes the flow properties of the plasticized plastic, which depend significantly on the viscosity and thus the melt flow index. The flow direction of the plastic melt depends on the flow resistance, which is influenced by the cross-sections through which it flows and their geometric shape. The initially largely radial spreading movement of the plastic melt in the injection collar 10 is caused by the fact that the dimensioning and shape of the injection collar 10 offers the plastic melt a lower flow resistance than the flow gap 30. Once the injection collar volume is filled with plastic melt due to its radial movement, the movement occurs axially into the flow gap 30 under the pressure applied to the plastic melt during the injection molding process.

[0042] Figure 5 comprises a perspective and abstracted detailed view of the insulation layer 30' adjacent to the winding space from the viewing direction of the gate 20. The gate collar 10 has a square or rectangular cross-section with a gate collar width b and a gate collar height h. It has been shown that a ratio of the gate collar width b and the gate collar height h in a range of 0.5 to 1 is well suited to initially guide the plastic melt radially in the gate collar 10, i.e. 0.5<=b / h<=1. To influence the plastic melt flow and the seal feeding of the flow gap, the cross-sectional ratios of the gate 20 and the gate collar 10 are matched to the cross-section of the flow gap 30. In a preferred

[0043] The cross-sectional area ratio of flow gap 30 and injection collar 10 is in a range from 0.5 to 1 and the cross-sectional area ratio of injection 20 and injection collar 10 is in a range from 1 to 1.4.

[0044] Figure 6 illustrates a plan view of a lamella 2 of the lamella pack for planes outside the injection collar plane.

[0045] Figure 7 shows a plan view of a gating lamella 21 of the lamella pack 1 for the gating plane and / or the gating collar plane.

[0046] Figure 8 shows a plan view of a gate collar lamination 21 of the lamination pack 1 for the gate collar plane. The gate collar 10 is formed by notched areas in the gate collar lamination 21 adjacent to the winding space 40. The gate collar is largely circumferential on the inner wall of the gate collar lamination 10 with gate collar outlets 12 adjacent to the winding groove 41.

[0047] Figure 9 shows a sectional top view of the lamination stack 1 in the injection collar plane. Several windings are schematically depicted within the winding space 40. In the final assembly situation, the winding space 40 is filled as completely as possible with windings and is electrically non-conductively insulated from the lamination stack 1 by the insulation layer 30'. In the area of ​​the injection collar 10, which runs partially and largely inside the winding space 40 adjacent to the lamination stack 1, the total width shown is equal to the injection collar width b plus the width of the flow gap width bf. The flow gap width bf of the flow gap 30 provided during injection molding defines the width of the insulation layer 30' outside the injection collar plane after production.

[0048] Figure 10 includes a sectional top view of the lamination stack 1 outside the injection collar plane, which is formed by the layering of laminations 2 and / or injection laminations 21. The flow gap width bf is largely constant adjacent to and largely continuous with the winding space 40, but can also vary. In the area of ​​the winding groove 41 and thus adjacent to the injection collar outlet 12, the insulation layer 30' can be thicker-walled due to an enlarged flow gap width bf and the design of the area.

[0049] The embodiment shown in the figures comprises lamination packs 1 with a plurality of winding spaces 40 bordered by tooth-shaped laminations 2. Likewise, the invention also includes embodiments based on laminations 2 with a tooth-shaped contour (“single tooth”).

Claims

Patent claims 1. A lamination pack (1) designed as a rotor or stator for an electrical machine, comprising a plurality of laminations (2) stacked in the axial direction, the lamination pack (1) comprising at least one winding space (40) and at least one injection molding (20), the wall of the lamination pack (1) having an insulation layer (30') in the direction of the winding spaces (40), characterized in that in each wall of the lamination pack (1) in the direction of a winding space (40) at least one injection molding collar (10) is arranged, which is in a communicating operative connection with the respective insulation layer (30') and the at least one injection molding (20), the injection molding collar (10) being formed by at least one injection molding collar lamination (11).

2. Laminated core (1) according to claim 1, characterized in that the at least one injection-molded collar (10) is arranged in regions circumferential to the adjacent winding space (40).

3. Disc pack (1) according to claim 1, characterized in that the at least one injection collar (10) has at least one injection collar outlet (12) in a region adjacent to the winding groove (41).

4. A lamination pack (1) according to claim 1, characterized in that the axial cross-sectional area ratio of the insulation layer (30') and the injection-molded collar (10) is in a range from 0.2 to 1.

5. Disc pack (1) according to claim 1, characterized in that the cross-sectional area ratio of the injection (20) and the injection collar (10) is in a range from 1 to 1.

4.

6. Disc pack (1) according to claim 1, characterized in that the injection collar width b is formed by a notch area in the injection collar disc (11).

7. A lamella pack (1) according to claim 1, characterized in that the injection collar height h is formed by the number of stacked injection collar lamellae (11).

8. Laminated section (1) according to claim 6 and 7, characterized in that the width ratio of the injection collar width b and the insulation layer width bf is in a range from 5 to 8.

9. Disc pack (1) according to claim 6 and 7, characterized in that the ratio of the injection collar width b and the injection collar height h is in a range of 0.5<=b / h<=1.

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