METHOD FOR MANUFACTURING A STATOR OF A DYNAMOELECTRIC MACHINE

Description

[0001] The invention relates to a method for impregnating a stator of a dynamo-electric machine, a device for carrying out the method, a stator of a dynamo-electric machine and a dynamo-electric machine.

[0002] Dynamoelectric machines have a winding system in slots of a stator which, when energized, generates a magnetic field and, due to electromagnetic interaction with a rotor, causes a rotational movement of a shaft that is non-rotatably connected to the rotor.

[0003] The winding system, d.h. The motor winding in the stator slots is insulated from the stator core by slot insulation, specifically a slot box, and covered by a cover plate towards the slot slot or air gap of the dynamo-electric machine. The slot insulation primarily covers the slot sides and bottom.

[0004] The fill level of a groove with z.B. The proportion of copper wires to the total slot cross-section in a stator lamination stack is approximately 80%.

[0005] Due to the mechanical internal stress in the winding wire and irregularities in the wire routing within the groove, the cover slide, which is inserted last, is generally pushed radially away from the bottom of the groove, creating empty spaces between the winding wires. These undesirable gaps or cavities occur between the groove side wall and the groove box insulation, between the groove box insulation and the winding wire, between individual winding wires, and between the winding wire and the cover slide.

[0006] These cavities reduce the fill level of the groove, which reduces the efficiency of a dynamo-electric machine.

[0007] Furthermore, these cavities or air inclusions in the winding system in the area of ​​the slot reduce the dielectric strength of the winding in the slot area during operation of the dynamo-electric machine.

[0008] According to this, short circuits in the winding system, as a cause of failure in a winding system, occur predominantly in the slot area.

[0009] Furthermore, especially external cavities, i.e. cavities in the area of ​​the slot side walls, hinder the heat dissipation from the winding wire or from the winding system to the stator lamination.

[0010] To reliably prevent cavities in the winding systems in the area of ​​the stator slots of a dynamoelectric machine, technically and time-consuming impregnation processes, such as z.B. Vacuum potting was used.

[0011] In addition to vacuum potting, there are u.a. The immersion impregnation process. When immersing a winding system of a dynamo-electric machine, air inclusions are almost unavoidable. The aim is to fill these cavities with impregnating resin as much as possible. This is only partially successful and results in higher resin consumption. Furthermore, increased resin absorption can only be achieved with higher temperatures and longer process times, or with "faster" impregnating resins. However, this leads to the formation of unwanted resin layers on the outer diameter of the lamination stack, in the stator bore, and drips at the winding head. This excess resin then requires time-consuming removal.

[0012] The winding system in the slots and / or winding heads is filled or coated with insulating resin and then cured. This impregnation fills voids in the dielectric and in the heat flow paths. This prevents glow discharges and reduces thermal resistance. The impregnation also provides mechanical strengthening.

[0013] In the production of a low-voltage electric motor (industrial motors or e-mobility motors up to 1 kV), impregnation with liquid reactive resin and subsequent curing is a very time-consuming and costly process compared to other manufacturing steps such as winding, insertion, and phase separation. This often involves large immersion impregnation stations. The impregnation process itself is an integrated process, with many shaft heights and sizes undergoing a dipping and / or temperature profile. Therefore, it is virtually impossible to individually optimize the impregnation parameters for a specific motor type.

[0014] Also known is the so-called trickle impregnation method, an impregnation technique for highly defined processes. In this method, liquid resin is applied to the rotating stator using highly precise dosing systems. Preheating the stator reduces the viscosity of the resin, thereby promoting the capillary effect and allowing the stator groove to gradually fill with resin.

[0015] When applying the resin to the rolling stator, several parameters must be considered to ensure optimal and, above all, sufficient resin flow into the slots. It is therefore essential to ensure that the impregnating medium flows to the axial slot center point, even with axially longer lamination stacks, and only gels there.

[0016] This is particularly relevant when using two-component liquid resins, which have a relatively fast gel time. This means that even at low temperatures, a viscosity limit is exceeded within a short time, significantly reducing the substance's flowability. While this effect is desirable for achieving a drip-free stator in the short term, it places particularly high demands on the resin's flowability and the stator's absorption capacity.

[0017] Due to the high variance of low-voltage motors (different shaft heights, shaft lengths, winding types, wire diameters, etc.), the trickling jet of a trickling system encounters a wide variety of substrates and conditions within the slot, all of which must meet these minimum requirements for absorption capacity in order to ultimately ensure sufficient operational reliability of the dynamoelectric machines.

[0018] Various types and quantities of sheet insulating materials (e.g., phase separators) within the groove can create barriers that prevent the resin from flowing optimally into the winding. These sheet insulating materials (e.g., Nomex papers, multilaminates made of PET film and aramid fabric) are flat sheets that the resin cannot penetrate, forcing the resin to flow around them. This effect also slows down the penetration into the groove and, in the worst case, even prevents the groove from being completely filled.

[0019] Poor flow behavior into the groove can currently be reduced by adjusting the resin. The resin chemistry can be modified to create a more fluid material, which may also have a delayed gelation point, allowing the material to flow more quickly around flow barriers and along long winding sections or grooves.

[0020] However, reducing viscosity is often no longer achievable from a chemical or technical perspective, as it is no longer desirable or even permitted under health regulations. Lower viscosities can often only be achieved with shorter molecular chain lengths and / or reactive diluents.

[0021] A delayed gel point of an impregnating resin is technically possible, but counterproductive from an economic point of view, as this increases the cycle times in the manufacturing process of a stator and / or the energy costs for curing the resin.

[0022] Impregnation methods for dynamoelectric machines are known from US 2005 / 280321 A1 and JP S61 247256 A.

[0023] Based on this, the invention aims to improve the impregnation of a winding system in the slots of a stator under the parameters mentioned above and to provide a stator and a dynamoelectric machine with reliable impregnation.

[0024] The problem is solved by a method for manufacturing a stator of a dynamoelectric machine according to claim 1.

[0025] The problem can also be solved by a device for manufacturing a stator of a dynamoelectric machine according to claim 6.

[0026] In the inventive method, resin is first trickled onto the winding heads of the dynamoelectric machine. Due to its low viscosity, the resin capillarizes into the slot area. This is followed by the gelation phase, during which the viscosity increases. In this phase, pressure is applied radially from the inside – i.e., from the direction of the slot – to the cover slide towards the bottom of the slot, thus compacting the slot contents. Voids are eliminated. The introduced impregnating resin distributes itself evenly and, due to the compaction, also fills areas within the winding that are difficult to fill. The pressure applied radially towards the bottom of the slot to the cover slide is exerted and maintained until, due to the resin beginning to solidify, the cover slide is prevented from springing back after pressure release. The cover slide is radially displaced from its initial position towards the bottom of the slot and is then positioned and fixed in place.

[0027] This is made possible by a type of lamellar press that applies radial pressure to the cover slide of all slots of the stator simultaneously along the entire length of the slot. This pressure acts in a pulsating manner to increase functionality.

[0028] Another compaction method can be achieved using a wheel or roller that exerts pressure radially towards the bottom of the slot while moving axially back and forth along the length of the slot, also in a pulsating manner according to the invention. This preferably occurs simultaneously in all slots of a stator to achieve sufficient compaction of the winding in the respective slots before gelation.

[0029] This radial pressure exerted during gelation ensures an even distribution of the impregnating resin throughout the groove and around the winding wires.

[0030] This process continues until the cover slide remains in its pressurized position in the groove.

[0031] In contrast to conventional dip impregnation methods, this process compacts the groove contents, particularly during the gelling phase, making the compaction especially effective. The cover plate adheres to the compressed winding wires via the impregnating resin and is not fixed by the core wire as is usually the case.

[0032] According to the invention, there are no air inclusions in the winding system in the slot. This increases the dielectric strength of the stator winding system while simultaneously reducing its susceptibility to vibration.

[0033] By compacting the winding wires in the stator slot, the winding wires make better contact with the slot box. This creates comparatively good thermal contact with the slot side walls, thereby increasing heat dissipation from the winding system in the slot area to the stator sheet by up to 10-15%.

[0034] Furthermore, the compaction of the winding wires increases the vibration resistance and / or dielectric strength of a drip impregnation winding.

[0035] The position of the cover slide is therefore offset towards the bottom of the groove compared to conventional methods.

[0036] The term "cover slide" refers to a surface insulating material, which is designed as a strip, particularly in the case of trickle windings, is arranged in the area of ​​the slot of a groove and positions the winding in the grooves.

[0037] When the winding is inserted into the laminated core, sheet insulation is also placed in the slots. A so-called slot box serves as the slot lining. This is a folded sheet insulation material whose cross-sectional shape is ideally adapted to the contour of the slot and rests against the slot wall. The slot lining thus forms an additional, flat electrical barrier between the winding system, in particular the copper winding made of enameled wire, and a magnetically conductive body, such as a laminated core.

[0038] After the winding is inserted, the slot is closed with a cover slide according to the invention, which also consists of a folded sheet insulating material and has two important functions. Firstly, this creates the necessary air and creepage distances, as the cover slide and slot box overlap at the edges. Secondly, the slot box wedges itself against the slot and thus mechanically fixes the winding in the slot, preventing individual wires from slipping back through the slot into the area of ​​the air gap or the rotor.

[0039] Together with the groove box, the cover slide forms a main channel for each groove, which is supplied with impregnating resin during the impregnation process and contains the winding, in particular copper winding.

[0040] In one version, the cover slide can also be double-layered to create a secondary channel for the impregnating resin. The two layers are separated from each other. This provides multiple efficient flow channels for the incoming impregnating resin in each groove.

[0041] The flow tubes within the two layers are formed by a corrugation of one layer, and / or perforations are present in one layer - on the layer facing the winding system - which ensure or at least support a predetermined distribution of the resin within the axial length of the groove.

[0042] In this design, a double layer of the cover slide creates a flow channel, with openings at the axial groove exit. The inner layer of the cover slide can be perforated, i.e., provided with outlet holes, or split into two parts with a non-flush joint in the center of the sheet. The cover slide itself could be grooved on one side in the longitudinal or axial direction, creating a well-defined flow channel, particularly towards the center of the groove.

[0043] The insertion of single- or double-layered cover slides into long sheet metal stacks is typically a manual manufacturing process. Therefore, inserting a double-layered cover slide does not represent a significant additional manufacturing time and can thus be implemented cost-effectively.

[0044] During impregnation, the winding system is filled or coated with insulating resin in the slots and / or winding heads and then cured. Impregnation fills voids in the dielectric and heat flow paths, preventing glow discharges and reducing thermal resistance. Impregnation also contributes to mechanical hardening. The additional radial pressure applied by a lamellar press or rollers further reduces thermal resistance and improves hardening.

[0045] The inventive method reduces the impregnation times of the stator and also creates a high-quality impregnation of the stator and thus of a dynamoelectric machine, which can ensure reliable operation of the dynamoelectric machine.

[0046] Such a method can be implemented, for example, by a device according to the invention for manufacturing a stator of a dynamoelectric machine. In this process, a magnetically conductive body, in particular a laminated core, is positioned in a holding device. This core has a winding system arranged in substantially axially extending slots. This stator winding system forms winding heads on the end faces of the magnetically conductive body. During a rotating and / or wobbling motion of the holding device and thus of the magnetically conductive body, impregnating resin is applied, in particular trickled, to these winding heads.During and / or immediately after the dripping process, auxiliary devices attached to the holding device, which have rotating and / or wobbling means, apply radial pressure to all grooves simultaneously in order to radially compress the respective groove contents of the magnetically conductive body during an impregnation process. Pressure on the cover slide achieves a distribution of the impregnating resin and compression of the winding in the groove.

[0047] The invention and further advantageous embodiments of the invention are explained in more detail in the following schematic drawings. These show: FIG 1 a longitudinal section of an electrical machine shown in principle, FIG 2 a cross-section of a groove, FIG 3, 4 a cross-section of a groove during compression, FIG 5 axial stroke towards the center under radial pressure.

[0048] FIG 1 Figure 1 shows a longitudinal section of a dynamoelectric machine 1, representing the basic structure. The machine has a stator 2 with axially extending slots 7 in which a winding system 19 is arranged. Across an air gap 20, the energized winding system 19 of the stator 2 magnetically interacts with a rotor 3, which causes the shaft 4 to rotate about an axis 5. The dynamoelectric machine 1 is enclosed in a housing (not shown in detail) which is supported on the shaft 4 by bearings.

[0049] When the winding system 19 is inserted into the slots 7 of a stator stator core 9, or even before this process, sheet insulation is also introduced into the slots 7. The slot lining is the so-called slot box 11, which is a folded sheet insulation material whose cross-sectional shape ideally conforms to the contour of the slot 7 and rests against the slot side wall 21 and the slot bottom 13. Different types and quantities of sheet insulation (e.g., phase separators) can create barriers that prevent the resin from flowing optimally into the winding system 5, a problem that is avoided by the method described below.

[0050] These sheet insulating materials (e.g., Nomex papers, multilaminates made of PET film and aramid fabric) are flat sheets that cannot be penetrated, but rather force the resin to flow around them. The method described below is used to accelerate this potentially necessary flow.

[0051] The slot lining or slot insulation 11 forms an additional planar electrical barrier between the winding system 19, in particular a copper winding implemented as enamelled wire, and a magnetically conductive body, for example a laminated core 9 of the stator. 2.

[0052] In the manufacture of such a low-voltage electric motor, as typical industrial motors or e-mobility motors up to 1kV, the impregnation of the winding system 19 with liquid reactive resin and the subsequent hardening of the same is a very time-consuming and costly process compared to the other manufacturing steps of the winding system 19 such as winding, drawing in, phase separation, etc.

[0053] In order to obtain a defined, time-compact impregnation process of the winding system 19, the trickling method is used, among other things, whereby a liquid impregnating resin is applied to the stator 2, which rolls by means of a device, by means of highly precise dosing systems.

[0054] An optional preheating of the stator 2 reduces the viscosity of the impregnating resin, thereby promoting the capillary effect of the impregnating resin into the slot 7 and into the cavities 22 between the winding wires 10 of a slot 7, and thus the slot 7 of the stator 2 gradually fills with resin.

[0055] When applying the resin, especially to a rolling stator 2, several parameters must be considered to ensure optimal and, above all, sufficient resin flow into the slots 7. In other words, it must be ensured that the impregnating medium flows to the axial and / or radial center of the slot 7, even with axially longer lamination stacks 9, and only then gels.

[0056] This is particularly important when using two-component liquid resins, which have a comparatively short gel time, as this means that even at low temperatures a viscosity limit is exceeded within a short time and thus the flowability of the substance, i.e. the impregnating resin, is significantly reduced.

[0057] FIG 2 Figure 1 shows a cross-section of a slot 7 of the dynamo-electric machine 1, which has a winding system 19 formed from a plurality of round wires 10. Other electrical conductors with different cross-sections can also be inserted in the slot 7. The slot side wall 21 and the slot bottom 13 are provided with slot insulation 11. The cavities 22, which, among other things, reduce the fill level of the slot 7, are visible.

[0058] A cover slide 15 covers the groove 7 towards the air gap 20. In this phase of the stator 2 manufacturing process, the cover slide 15 is positioned directly at the slot 14 and points towards the air gap 20 of the dynamo-electric machine 1. An overlap is formed with the groove insulation 11, such that the cover slide 15 is located at least partially within the groove insulation 11.

[0059] FIG 3 Figure 1 shows the basic process of radial pressure applied by a lamellar press 16 in a groove 7. After the resin is dripped onto the winding heads 6 and capillaries into the groove area due to its low viscosity, the gelation phase follows, during which the viscosity increases. In this phase, radial pressure is applied from the inside, i.e., from the direction of the groove slot 14, to the cover slide 15 towards the groove bottom 13, thus compacting the groove contents. Voids 22 are eliminated. The introduced impregnating resin spreads evenly and, due to the compaction, also fills areas within the winding system 19 in the groove area that are difficult to fill. The radially applied pressure towards the groove bottom 13 on the cover slide 15 is maintained until the resin begins to solidify, preventing springback after pressure release.The cover slide 15 is radially displaced from its initial position towards the bottom of the groove 13 and is positioned and fixed there.

[0060] This is made possible by a type of lamellar press 16, which radially exerts pressure on the cover slide of all slots of the stator 2 along the entire axial length of the groove 7. To increase functionality, this pressure acts pulsatingly from the lamellar press 16 onto the cover slide.

[0061] Another way to compact the material is by using a wheel or roller. FIG 4 This occurs when pressure is exerted radially on the cover slide 15 towards the bottom of the slot 13, while the slide moves axially back and forth along the slot length, and according to the invention, also radially pulsating. This preferably occurs simultaneously on all slots 7 of a stator 2 in order to achieve sufficient compaction of the winding in the respective slots 7 before gelling.

[0062] FIG 5Another version shows two rollers per groove which, during gelation, brush the resin towards the center while exerting radial pressure on the cover slide 15 and thus on the winding wires 10.

[0063] All the compression measures shown ensure a uniform distribution of the impregnating resin throughout the entire groove 7 and around the winding wires 10.

[0064] This process of radial compression continues until the cover slide 15 remains in its pressurized position in the respective groove 7.

[0065] In contrast to conventional immersion impregnation methods, this method compacts the groove contents, i.e., the winding wires 10 of the winding system 19, particularly during the gelation phase, making the compaction especially effective. The cover slide 15 adheres to the compressed winding wires 10 by means of impregnating resin and is not fixed by the slot 12 as is usually the case.

[0066] According to the invention, no air inclusions are present in the winding system 19 in the slot 7. This increases the dielectric strength of the winding system 19 while reducing its susceptibility to vibration.

[0067] By compacting the winding wires 10 in the slot 7, the winding wires 10 also make better contact in the area of ​​the slot box. This creates comparatively good contact with the slot side walls 21, thereby increasing the heat dissipation from the winding system 19 in the area of ​​the slot 7 to the stator sheet 2 by 10-15%.

[0068] This ensures that a sufficient amount of resin is obtained in the winding system 19, particularly in the central area of ​​the groove 7. This is especially advantageous when using a two-component liquid resin, which has a relatively short gel time. Even at low temperatures, the viscosity limit is not exceeded as quickly according to the invention, thus increasing the flow range.

[0069] The position of the cover slide 15 in the groove 7 is offset towards the bottom of the groove 13 compared to conventional methods, which benefits, among other things, axial air cooling in the area of ​​the air gap 20.

[0070] It is advantageous if this method of impregnating a stator 2 is carried out by means of a device to which the necessary auxiliary devices can be attached modularly and adjusted accordingly via a control system.

[0071] A dynamoelectric machine 1 equipped with such a stator 2 exhibits reliable impregnation, which ensures reliable operation of the machine 1, enabling its use even in demanding drive applications. This includes, among other things, reduced glow discharge and improved heat dissipation from the stator winding system.

[0072] Thus, such dynamoelectric machines 1 are used in industrial environments, among other things, as drives for conveyor belts, compressors, pumps, as well as in mobile drives.

Claims

1. Method for producing a stator (2) of a dynamoelectric machine (1): - providing a magnetically conductive body of a stator (2) of a dynamoelectric machine (1) with substantially axially running slots (7), in particular a hollow-cylindrical laminated core (9), wherein the slots (7) have a slot opening (14), slot side walls (21) and a slot base (13), wherein slot teeth (12) are formed between the slots (7), - inserting a winding system (19) into the slots (7), wherein winding overhangs (6) are formed on the end faces of the magnetically conductive body, wherein the winding system (19) has electrical conductors formed as winding wires (10), - inserting a cover slide (15) onto each winding of a slot (7) on the side facing toward a slot opening (14), as a radial end of the windings toward the slot opening (14), - applying, in particular trickling, impregnating resin onto the winding overhangs (6), at least on one end face of the magnetically conductive body, wherein the impregnating resin, due to the comparatively low viscosity, capillates substantially axially into the slot area between the winding wires (10), - exerting a radial pressure on the cover slides (15) of the respective slot (7), such that the slot content - i.e. the individual winding wires (10) of this slot (7) - is compressed and condensed during the gelling phase of the impregnating resin, until the cover slides (15) remain in their pressurized position in the respective slot (7) and / or the impregnating resin is distributed homogeneously in the respective slot (7), characterized in that the radial pressure is effected by a laminating press or rollers and acts on the cover slide (15) in a pulsating manner.

2. Method for producing a stator (2) of a dynamoelectric machine (1) according to Claim 1, characterized in that the radial pressure is effected by means of a laminating press (16), which presses on the cover slides (15) of the slots (7) simultaneously, during or after the trickling process of the impregnating resin onto the winding overhang (6) of the stator (2).

3. Method for producing a stator (2) of a dynamoelectric machine (1) according to Claim 1, characterized in that the radial pressure is effected by means of a roller which runs axially to and fro in the respective slot openings (14) and which in each case exert radial pressure on the cover slides (15) of the slots (7) simultaneously, during or after the trickling process of the impregnating resin onto the winding overhang (6) of the stator (2).

4. Method for producing a stator (2) of a dynamoelectric machine (1) according to Claim 1, characterized in that the radial pressure is effected by means of two rollers which run from the end face and which sweep under pressure to the centre of the respective slot (7).

5. Method for producing a stator (2) of a dynamoelectric machine (1) according to any one of the preceding claims, characterized in that the impregnating resin is applied to the winding overhang or overhangs (6) of a rolling, in particular obliquely rolling or wobbling, stator (2).

6. Device for producing a stator (2) of a dynamoelectric machine (1) by means of the method according to Claim 1, with at least one holding device of a magnetically conductive body of the stator (2), with a winding system (19) arranged in slots (7) with an in slots of the magnetically conductive body, wherein the holding device allows a rotating and / or tumblingly rolling movement of the magnetically conductive body, wherein, during this movement, impregnating resin can be applied to a winding overhang (6) of the winding system (19) of the magnetically conductive body, wherein the device comprises an auxiliary device, which can be attached to the holding devices and which has at least one laminating press or roller which rotates and / or tumblingly rotates therewith in order to compress a respective slot content of the magnetically conductive body in a radially pulsating manner during an impregnation process.