Rotating electric machine and coil fixing method for rotating electric machine

Abstract

A dynamo-electric machine in which a coil wrapped in an insulating sheet is fixed to a slot provided to an iron core, wherein: the insulating sheet has a porous structure; the coil and the insulating sheet, and the insulating sheet and the iron core, are fixed by an insulating varnish dispersed by ultrasonic irradiation; and, a mixed layer in which the insulating varnish and the insulating sheet are mixed is formed by permeation by the insulating varnish to a prescribed extent in the insulating sheet at least from the surface layer to the interior.

Description

[Technical field]

[0001] The present invention relates to a rotating electric machine and a coil fixing method for the rotating electric machine. [Background technology]

[0002] In a rotating electric machine having an iron core, a coil inserted into a slot provided in the iron core, and an insulating sheet interposed between the iron core and the coil, it is known that the coil is hardened with varnish to improve insulation performance and suppress deformation or movement of the coil. JP2020-150611A describes that the varnish is impregnated into the slot through the gaps in the coil windings, so that the varnish also permeates the insulating sheet made of paper or cloth, and further the varnish is filled between the insulating sheet and the stator. Summary of the Invention

[0003] Incidentally, varnish contains fillers for improving insulating and adhesive properties, and these fillers have the property of easily agglomerating. The agglomeration increases the apparent particle size of the varnish. Therefore, even if the varnish is impregnated through the gaps in the windings of the coil as in the above document, the varnish does not penetrate into the insulating sheet, and there is a risk that sufficient adhesive strength is not obtained. Furthermore, there is a risk that peeling occurs at the interface between the varnish and the insulating sheet due to vibration or input of external force, causing the coil to move.

[0004] In view of the above problems, the present invention has an object to provide a rotating electric machine and a coil fixing method that are configured to suppress deformation and movement of the coil.

[0005] According to one aspect of the present invention, there is provided a rotating electric machine having a coil wrapped in an insulating sheet fixed in a slot provided in an iron core, in which the insulating sheet has a porous structure, the coil and the insulating sheet, and the insulating sheet and the iron core are fixed by an insulating varnish that has been dispersed by ultrasonic irradiation, and a mixed layer in which the insulating varnish and the insulating sheet are mixed is formed by permeating the insulating sheet at least in a predetermined range from the surface layer to the inside.

[0006] According to another aspect of the present invention, there is provided a coil fixing method for a rotating electric machine, in which a coil wrapped in an insulating sheet is fixed in a slot provided in an iron core, in which an insulating varnish is dispersed by irradiating ultrasonic waves, and then the dispersed insulating varnish is impregnated into the insulating sheet and the coil inserted in the slot, and the insulating varnish that has impregnated the insulating sheet and the coil is cured. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram of a rotor of a rotating electric machine. [Diagram 2] FIG. 2 is an enlarged cross-sectional view of a portion of the rotor. [Diagram 3] FIG. 3 is a diagram showing the configuration of an apparatus for impregnating a coil with insulating varnish. [Figure 4] FIG. 4 is an enlarged cross-sectional view of the rotor impregnated with insulating varnish. [Diagram 5] FIG. 5 is an enlarged cross-sectional view of a comparative rotor. [Figure 6] FIG. 6 is a diagram showing a method for evaluating the torsional strength. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0009] 1 is a schematic diagram of a rotor 1 of a rotating electric machine according to this embodiment. In this embodiment, a rotating electric machine used as a drive source for a vehicle is assumed, but is not limited to this.

[0010] The rotor 1 includes a rotor shaft 2 as a rotating shaft, an iron core 3 fixedly supported by the rotor shaft 2, and a coil 4 fixedly supported by the iron core 3. Note that an insulating sheet 5 (see FIG. 2) wrapping the coil 4 is omitted in FIG. 1.

[0011] The core 3 is a laminate of disk-shaped steel plates and has a plurality of teeth 3A extending radially from the rotation axis. A space between adjacent teeth 3A is called a slot 3B.

[0012] The coils 4 are formed by winding a wire coated with enamel or the like around the teeth 3A. Although only one coil 4 is shown in Fig. 1, the coils 4 are formed in the same manner on all the teeth 3A. In other words, a coil 4 is disposed in each slot 3B.

[0013] Each coil 4 is electrically connected to the outside via a slip ring.

[0014] 2 is an enlarged cross-sectional view of a portion of the cross section of the iron core 3 and the coil 4 along a plane perpendicular to the rotor shaft 2. As shown in the figure, an insulating sheet 5 is disposed between the iron core 3 and the coil 4. The outer periphery of the coil 4 is also covered with the insulating sheet 5. In other words, the portion of the coil 4 located within the slot 3B is wrapped in the insulating sheet 5. This provides insulation between the iron core 3 and the coil 4, and between adjacent coils 4. Note that for the portion of the coil 4 protruding from the iron core 3 in the direction of the rotation axis, the insulating sheet 5 is only interposed between the iron core 3 and the coil 4.

[0015] The insulating sheet 5 used in this embodiment has a porous structure. For example, it is a so-called mesh-like sheet such as a sheet of nonwoven fabric, paper, or felt formed by intertwining fibrous members, or a sheet of knitted fabric formed by knitting fibrous members. The insulating sheet 5 used in this embodiment has a mesh diameter larger than the particle diameter of the insulating varnish 30 in a dispersed state described later.

[0016] During operation of the rotating electric machine, an external force such as centrifugal force acts on the coil 4. It is desirable that the coil 4 is not deformed or misaligned with respect to the iron core 3 even when this external force acts on it. In addition, if the windings rub against each other due to vibrations that occur during operation of the rotating electric machine, the coating such as enamel may be damaged.

[0017] In this embodiment, therefore, in order to prevent deformation and displacement of the coil 4 and to improve insulation, the gaps between the windings and the gaps between the coil 4 and the iron core 3 are filled with insulating varnish 30 (see FIG. 4) and mechanically fixed together. Note that the insulating varnish 30 used in this embodiment may be any varnish generally used for insulating coils of rotating electrical machines, and may be of any type, be it solvent type, non-solvent type, or water-soluble type. A method of fixing using insulating varnish will be described below.

[0018] In this embodiment, the rotor 1 with the coils 4 and insulating sheets 5 arranged in the slots 3B is immersed in liquid insulating varnish 30, thereby impregnating the gaps with the insulating varnish 30. As a result, the coils 4 and insulating sheets 5 are fixed to the iron core 3 using the insulating varnish 30. In the following description, impregnating the gaps with the insulating varnish 30 may also be referred to as "impregnating the coils 4 with the insulating varnish 30."

[0019] FIG. 3 is a diagram showing the configuration of an apparatus for impregnating the coil 4 with the insulating varnish 30. As shown in FIG.

[0020] The insulating varnish 30 is automatically or manually charged into the supply tank 11. The insulating varnish 30 in the supply tank 11 is sent from there to the ultrasonic processor 12 by the main pump 16, and is supplied to the main tank 13 after ultrasonic treatment. The ultrasonic treatment will be described later.

[0021] The insulating varnish 30 in the main tank 13 is supplied to the dipping tank 15 by the circulation pump 17, supplied from the dipping tank 15 to the reverse tank 14, and returned from the reverse tank 14 to the main tank 13 by the reverse pump 18, and this process is repeated. Note that, although four dipping tanks 15 are shown in FIG. 3, the number of dipping tanks 15 is not limited to this.

[0022] In addition, the main tank 13 is provided with a pipe 21 for returning the insulating varnish 30 to the supply tank 11, and by opening a valve 28 installed in the pipe 21, the insulating varnish 30 in the main tank 13 can be returned to the supply tank 11.

[0023] In the dipping tank 15, an impregnation step is performed in which the coil 4 is impregnated with the insulating varnish 30 by a so-called dipping method. Specifically, the rotor shaft 2 of the rotor 1 is rotatably supported at a position higher than the liquid level of the insulating varnish 30 in the dipping tank 15, and each coil 4 is sequentially dipped in the liquid insulating varnish 30 by rotating the rotor shaft 2. By performing this rotation for a predetermined time, the coil 4 can be impregnated with the insulating varnish 30. The "predetermined time" here is set appropriately depending on the shape of the coil 4, the number of turns and density of the winding, the components of the insulating varnish 30 used, etc. After the impregnation step is completed, the rotor 1 is removed from the apparatus, and the liquid insulating varnish 30 is cured.

[0024] The present apparatus also includes a cooling system that suppresses the temperature rise of the insulating varnish 30. The cooling system includes a coolant tank 23, a cooling pump 25 that circulates the coolant, a heat exchanger 27 that exchanges heat with the ultrasonic processor 12, a radiator 24 that cools the coolant whose temperature has risen due to the heat exchange, and a cooling water temperature sensor 26 that detects the temperature of the cooling water. In this embodiment, the heat exchanger 27 is disposed so as to surround the ultrasonic processor 12, and a configuration is adopted in which cooling is performed during ultrasonic processing, but this is not limited to this. For example, a configuration in which cooling is performed between the end of ultrasonic processing and the start of the impregnation process may be used.

[0025] The main pump 16, the circulation pump 17, the reverse pump 18 and the ultrasonic processor 12 are controlled by a controller 22 based on the detection values ​​of a flow meter 19 etc. The controller 22 also controls a cooling pump 25 based on the detection values ​​of a temperature sensor 20 and a cooling water temperature sensor 26.

[0026] Here, the reason for subjecting the insulating varnish 30 to ultrasonic treatment and its effects will be described.

[0027] Fillers for improving insulation and adhesiveness are added to the insulating varnish 30, and these fillers need to be sufficiently dispersed (also called a "dispersed state") in order to achieve the desired performance. However, the smaller the particle size of the filler, the more likely it is that the fillers will aggregate with each other, making it difficult to achieve a dispersed state.

[0028] When the filler particles aggregate, the apparent particle size of the insulating varnish 30 increases, making it difficult for the filler particles to penetrate into the gaps between the windings and the insulating sheet 5.

[0029] If the insulating varnish 30 does not penetrate into the gaps between the windings, the gaps will become voids after the insulating varnish 30 hardens. The more voids there are, the lower the strength of the coil 4 after the insulating varnish 30 hardens. In other words, if an insulating varnish 30 that is not in a dispersed state is used, there is a risk that the effect of suppressing deformation of the coil 4 when an external force is applied will not be obtained.

[0030] Furthermore, if the insulating sheet 5 is not permeated with the insulating varnish 30, the adhesive strength between the coil 4, insulating sheet 5, and iron core 3 will be lower than if the insulating sheet 5 is permeated (this will be described later). In other words, if insulating varnish 30 that is not in a dispersed state is used, there is a risk that the effect of suppressing displacement of the coil 4 when an external force is applied will not be obtained.

[0031] Therefore, in this embodiment, in order to put the insulating varnish 30 into a dispersed state, ultrasonic treatment is performed on the insulating varnish 30 by irradiating it with ultrasonic waves. If only considering putting the insulating varnish 30 into a dispersed state, ultrasonic treatment may be performed on the insulating varnish 30 in the dipping tank 15 in the above-mentioned impregnation step. In this case, however, the windings constituting the coil 4 vibrate due to the irradiation of ultrasonic waves, and the windings rub against each other, deteriorating the insulating coating. In contrast, in this embodiment, ultrasonic treatment is performed before impregnation into the coil 4, so deterioration of the insulating coating of the windings can be suppressed.

[0032] Furthermore, when ultrasonic waves are applied, the particles in the insulating varnish 30 vibrate, causing the temperature of the insulating varnish 30 to rise. Since a rise in temperature leads to accelerated deterioration of the insulating varnish 30, in this embodiment, the above-mentioned cooling system is used to suppress the temperature rise of the insulating varnish 30. However, if the temperature of the insulating varnish 30 is lower than the appropriate range, impregnation of the coil 4 becomes insufficient. Therefore, the controller 22 detects the temperature of the insulating varnish 30 using the temperature sensor 20, and controls the cooling pump 25 according to the detection result. The above-mentioned appropriate range is determined by the type, components, etc. of the insulating varnish 30 used.

[0033] Next, the effect of impregnating with insulating varnish 30 that has been subjected to ultrasonic treatment will be described. Fig. 4 is an enlarged cross-sectional view of a part of rotor 1 in which coil 4 is impregnated with insulating varnish 30 that has been subjected to ultrasonic treatment. The part referred to here is region A in Fig. 2. Fig. 5 is an enlarged cross-sectional view of a part of rotor 1 that has been impregnated with insulating varnish 30 that has not been subjected to ultrasonic treatment, which is a comparative example.

[0034] As shown in FIG. 4, the insulating varnish 30 that has been subjected to ultrasonic treatment permeates the gaps between the windings of the coil 4 and the gaps between the coil 4 and the iron core 3. In addition, a mixed layer ML in which the permeated insulating varnish 30 and the insulating sheet 5 are mixed is formed in a predetermined range from the surface layer to the inside of the insulating sheet 5. This is because the insulating varnish 30 is in a dispersed state by the ultrasonic treatment. The "predetermined range" here is determined according to the dispersed state of particles in the insulating varnish 30, which is determined by the ultrasonic treatment and the temperature of the insulating varnish 30 when the ultrasonic treatment is performed. In other words, the more dispersed the particles are, the easier it is for the insulating varnish 30 to permeate the insulating sheet 5, and therefore the larger the "predetermined range".

[0035] In contrast, when the coil 4 is impregnated with insulating varnish 30 that has not been subjected to ultrasonic treatment, voids V are scattered in the gaps between the windings of the coil 4, as shown in Fig. 5. Furthermore, the insulating varnish 30 does not permeate the insulating sheet 5, and a mixed layer is not formed. This is because the insulating varnish 30 is not in a dispersed state and cannot permeate the gaps between the windings or the insulating sheet 5.

[0036] As described above, there are structural differences between the cases where ultrasonic treatment has been applied and those where it has not been applied, such as the number of gaps between the windings and the presence or absence of a mixed layer. Below, we will explain the differences in characteristics caused by these structural differences.

[0037] [About adhesive strength] First, a method for evaluating differences in characteristics will be described.

[0038] A coil 4 was cut out from a rotor 1 in which the coil 4 was impregnated with insulating varnish 30 that had been ultrasonically treated, and this was used as sample 1. The portion cut out was the portion along the teeth 3A within the slot 3B. A coil 4 was similarly cut out from a rotor 1 in which the coil 4 was impregnated with insulating varnish 30 that had not been ultrasonically treated, and this was used as a comparative sample.

[0039] Then, the state of the surface (also called the comparison surface) of Sample 1 and the comparative sample that faced the insulating sheet 5 was compared. In both Sample 1 and the comparative sample, the insulating sheet 5 was peeled off during the process of cutting them out from the rotor 1.

[0040] Next, the evaluation results will be described. A part of the insulating sheet 5 was confirmed on the comparison surface of Sample 1. This shows that in Sample 1, the insulating sheet 5 was destroyed when it was peeled off.

[0041] In contrast, the insulating sheet 5 was not observed on the comparative surface of the comparative sample. This shows that the insulating varnish 30 did not permeate the insulating sheet 5 in the comparative sample, and the interface between the insulating varnish 30 and the insulating sheet was destroyed when the insulating sheet 5 was peeled off.

[0042] In general evaluations of adhesive bonding surfaces, it is said that a bonding surface where the adherend is destroyed when an external force is applied has a higher adhesive strength than a bonding surface where the interface between the adherend and the adhesive is destroyed. From this, it can be said that sample 1 had a higher adhesive strength with the insulating sheet 5 than the comparative sample. Furthermore, the fact that the insulating varnish 30 and the insulating sheet 5 are firmly bonded also means that the coil 4 and the insulating sheet 5 are firmly bonded. It is also presumed that the adhesion between the insulating sheet 5 and the iron core 3 is similarly strong.

[0043] From the above, it can be seen that by using insulating varnish 30 that has been subjected to ultrasonic treatment, the iron core 3, coil 4 and insulating sheet 5 are firmly bonded together, and displacement of the coil 4 relative to the iron core 3 when an external force is applied is suppressed, compared to the case where insulating varnish 30 that has not been subjected to ultrasonic treatment is used.

[0044] [About torsional strength] Fig. 6 is a diagram showing a method for evaluating torsional strength. The above-mentioned sample 1 and comparative sample are used as evaluation samples. Both ends of the evaluation sample are held by fixed chuck 31 and rotating chuck 32, respectively, and the evaluation sample is twisted by rotating chuck 32. Then, the force required to twist the sample by a predetermined angle is measured, and this is used as an evaluation index for the torsional strength.

[0045] For more accurate evaluation, multiple samples of Sample 1 and comparative samples were prepared, and the above evaluation was carried out for all samples.

[0046] The evaluation results showed that Sample 1 had 2-2.5 times the torsional strength of the comparative sample. Compared to the insulating varnish 30 that was dispersed by ultrasonic treatment, the insulating varnish 30 that was not dispersed is less likely to penetrate into the gaps between the windings. For this reason, the comparative sample had more voids in the gaps between the windings than Sample 1. It is presumed that the difference in the number of voids is reflected in the difference in torsional strength mentioned above.

[0047] The higher the torsional strength, the smaller the amount of deformation when an external force is applied. Therefore, Sample 1 can suppress the deformation of the coil 4 more effectively than the comparative sample.

[0048] In this embodiment, the iron core 3, the coil 4, and the insulating sheet 5 of the rotor 1 have been described, but the present invention can also be applied to the stator core (iron core), the stator coil, and the insulating sheet of a stator in the same manner.

[0049] As described above, in this embodiment, a rotating electric machine is provided in which the coil 4 wrapped in the insulating sheet 5 is fixed in the slot 3B provided in the iron core 3. The insulating sheet 5 has a porous structure, and the coil 4 and the insulating sheet 5, and the insulating sheet 5 and the iron core 3 are fixed by the insulating varnish 30 that is in a dispersed state by ultrasonic irradiation, and the insulating varnish 30 permeates at least a predetermined range from the surface layer to the inside of the insulating sheet 5 to form a mixed layer ML in which the insulating varnish 30 and the insulating sheet 5 are mixed. The insulating varnish in a dispersed state easily permeates the gaps between the windings of the coil 4. In addition, the formation of the mixed layer ML means that the adhesive strength of the insulating varnish 30 is high. Therefore, according to this embodiment, it is possible to suppress deformation and displacement of the coil 4 when an external force is applied.

[0050] In this embodiment, a coil fixing method for a rotating electric machine is provided, in which a coil 4 wrapped in an insulating sheet 5 is fixed to a slot 3B provided in an iron core 3. In this coil fixing method, an insulating varnish is dispersed by irradiating ultrasonic waves, and then the insulating sheet 5 and the coil 4 inserted in the slot 3B are impregnated with the dispersed insulating varnish 30, and the insulating varnish 30 impregnated in the insulating sheet 5 and the coil 4 is hardened. If ultrasonic treatment is performed at the same time as the process of impregnating the coil 4 with the insulating varnish 30, the coating of the winding constituting the coil 4 may rub against each other due to vibration caused by ultrasonic irradiation, and may be damaged. In contrast, in this embodiment, ultrasonic treatment is performed before impregnation, so that damage to the coating of the winding can be suppressed.

[0051] In this embodiment, the insulating varnish 30 is cooled before being impregnated into the insulating sheet 5 and the coil 4. The temperature of the insulating varnish 30 increases when ultrasonic waves are applied, but the increase in temperature leads to accelerated deterioration of the insulating varnish 30. In this regard, in this embodiment, the temperature increase can be suppressed, and therefore the deterioration of the insulating varnish 30 can be suppressed.

[0052] Although the embodiments of the present invention have been described above, the above-mentioned embodiments merely show some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above-mentioned embodiments.

Claims

1. In a rotating electric machine in which a coil wrapped in an insulating sheet is fixed in a slot provided in an iron core, The insulating sheet has a porous structure, the coil and the insulating sheet, and the insulating sheet and the iron core are fixed with insulating varnish, The insulating varnish contains at least one type of filler, and is subjected to ultrasonic treatment in which ultrasonic waves are irradiated to the insulating varnish while the insulating varnish contains the filler; A rotating electric machine in which the insulating varnish dispersed by the ultrasonic treatment penetrates into a predetermined area of ​​at least the surface layer and the interior of the insulating sheet, thereby forming a mixed layer in which the insulating varnish and the insulating sheet are mixed.

2. A coil fixing method for a rotating electric machine, in which a coil wrapped in an insulating sheet having a porous structure is fixed to a slot provided in an iron core, comprising the steps of: An insulating varnish containing at least one type of filler is subjected to ultrasonic treatment by irradiating ultrasonic waves, Then, the insulating varnish dispersed by the ultrasonic treatment is impregnated into the insulating sheet and the coil inserted into the slot, A coil fixing method for a rotating electric machine, comprising: hardening the insulating varnish impregnated into the insulating sheet and the coil, thereby forming a mixed layer in which the insulating varnish and the insulating sheet are mixed in a predetermined area from at least the surface to the inside of the insulating sheet.

3. 3. The coil fixing method for a rotating electric machine according to claim 2, The method for fixing a coil in a rotating electric machine further comprises cooling the insulating varnish before impregnating the insulating sheet and the coil.

4. 2. The rotating electric machine according to claim 1, The insulating sheet is a mesh-like sheet having a mesh diameter larger than the particle diameter of the insulating varnish in a dispersed state.

5. 2. The rotating electric machine according to claim 1, A rotating electric machine, wherein the predetermined range is determined according to a dispersion state of particles in the insulating varnish which is determined by the ultrasonic treatment and the temperature of the insulating varnish when the ultrasonic treatment is performed.

6. 3. The coil fixing method for a rotating electric machine according to claim 2, The method for fixing a coil of a rotating electric machine, wherein the insulating sheet is a mesh-like sheet having a mesh diameter larger than the particle diameter of the insulating varnish in a dispersed state.

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