JP6906329B2 - Manufacture method of stator, rotary electric machine, stator, and manufacturing method of rotary electric machine - Google Patents

Description

The present invention relates to a stator, a rotary electric machine, a method for manufacturing a stator, a method for manufacturing a rotary electric machine, and a coil wire used for the stator.

Rotating electric machines, which are closely related to industry and daily life, are the basic equipment that supports modern society. In particular, from the viewpoint of protecting the global environment, hybrid vehicles and electric vehicles are becoming widespread. In these automobiles, the motor of the power source is required to be smaller and lighter from the viewpoint of securing the installation space and improving the fuel efficiency by reducing the weight.

The insulator of the stator slot of the power motor used in hybrid vehicles and electric vehicles is the insulating paper (slot liner) inserted between the stator core / coil and the out-of-phase coil, and the coil and insulating paper that fill the gaps between them. It is composed of a fixing varnish that fixes the core to the core (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2013-9493

In order to reduce the size of the power motor, it is conceivable to increase the drive voltage or increase the coil current density. However, since either means leads to an increase in the load in the insulating portion of the coil in the stator, it is necessary to design an insulating structure for miniaturization.

In the case of using a means for increasing the drive voltage, in order to deal with it as an extension of the conventional technique, the thickness of the insulating paper is increased and the insulation distance corresponding to the working voltage is secured. However, in this method, the coil space factor in the slot is lowered, and the coil current is lowered. To compensate for this point, it is necessary to increase the coil current density, and the temperature rise of the coil is unavoidable.

When another means for increasing the coil current density is used, the temperature of the coil rises as in the above case, which is an obstacle when miniaturizing the power motor used for the hybrid vehicle or the electric vehicle. ..

In the insulating portion of the conventional stator, a thermosetting resin is used as the fixing varnish so that the fixing force does not decrease even if the temperature rises due to the operation of the motor. In order to firmly fix the constituent members in the slot, a resin having a low viscosity is used in consideration of the permeability into the voids between the constituent members.

In general, it is difficult to improve the heat resistance of a thermosetting resin having low viscosity, and the temperature rise of the coil due to the increase in coil current density causes the insulation reliability due to the thermal deterioration of the fixed resin in the insulating portion of the slot. It causes a decrease in.

An object of the present invention is to prevent thermal deterioration of the fixing resin and improve the insulation reliability of the stator when the temperature of the stator coil rises and a high voltage is applied to the stator coil.

The stator of the present invention comprises a core having a core back and teeth, a conductor coated with an insulating layer, and an electric wire containing a first resin covering the outer surface of the insulating layer, and is a bundle of electric wires. A second resin is provided on at least the corners of adjacent electric wires on the outer surface of the segment coil.

According to the present invention, when the temperature of the stator coil rises and a high voltage is applied to the stator coil, resin cracks caused by thermal deterioration of the fixed resin are prevented, and a decrease in the partial discharge start voltage caused by the resin cracks is prevented. It is possible to improve the insulation reliability of the stator.

It is a front view which shows the stator core cut out for the insulation model assembly used in an Example and a comparative example. It is a perspective view which shows the assembled insulation model. It is sectional drawing which shows the assembled insulation model. It is an enlarged cross-sectional view which shows a part of the simulated coil of an Example. It is an enlarged cross-sectional view which shows a part of the simulated coil of an Example after performing a thermosetting treatment. It is a schematic perspective view which shows the resin crack after thermal deterioration of the comparative example. It is a partially enlarged cross-sectional view which shows the detailed structure of the simulated coil of Example 1 after the thermosetting treatment. It is a flow chart which shows the example of the manufacturing method of the stator of an actual machine. It is sectional drawing which shows the rotary electric machine provided with the stator of this invention. It is a perspective view which shows the state before inserting a stator into a housing. It is a schematic cross-sectional view which shows the example of the coil electric wire of this invention.

The present invention relates to a stator, a rotary electric machine, a method for manufacturing a stator, a method for manufacturing a rotary electric machine, and a coil wire used for the stator. Rotating electric machines are applied to electric vehicles and the like.

The following is an insulation model in which a simulated coil and slot insulating paper are incorporated into a core cut out from a stator core having an outer diameter of 245 mm, an inner diameter of 200 mm, a number of slots of 72, and a core thickness of 94 mm, and the components inside the slots are fixed in each resin configuration. An embodiment of the present invention will be described with reference to the result of measuring the partial discharge start voltage. The examples and comparative examples described later are partial models of the stator of the rotary electric machine, but as is obvious from the following explanation, they are equivalent to the stator of the actual rotary electric machine.

FIG. 1 shows the shape of the stator core cut out for assembling the insulation model.

In this figure, the core 1 is formed by cutting a substantially cylindrical stator core into a fan shape having a central angle of 5 °, and is composed of a core back 16 and teeth 17a and 17b. One slot 2 is provided between the teeth 17a and 17b.

The shape of the slot 2 is a substantially rectangular shape having a constant width, the width thereof is 4.2 mm, and the depth of the parallel portion is 12.1 mm. A punched electrical steel sheet equivalent to 35A300 (JIS C 2552) is used for the core 1. The electromagnetic steel plates constituting the core 1 are laminated and fixed by welding the outer peripheral surface of each electrical steel plate.

FIG. 2 is a perspective view showing the assembled insulation model. Further, FIG. 3 is a cross-sectional view showing an assembled insulation model.

As shown in these figures, in the insulation model, four copper conductors (coil wires) are stacked to form a simulated coil 4 (segment coil), and the central portion of the simulated coil 4 is wrapped with slot insulating paper 5, and these are wrapped. It has a configuration inserted into the slot of the core 1. Each simulated coil 4 is formed of a flat enamel insulated wire. The simulated coil 4 (segment coil) can also be called a bundle of electric wires.

The length of the simulated coil 4 is 160 mm. The simulated coil 4 protrudes 33 mm evenly from both ends of the slot. The flat-angle enamel-insulated wire is obtained by coating the surface of a flat-angle copper conductor (copper wire) with a polyimide insulating layer having a thickness of 0.05 mm. The cross-sectional dimensions of the flat enamel insulated wire are a short side of 2.89 mm, a long side of 3.42 mm, and a corner chamfer radius of 0.5 mm.

As the slot insulating paper 5, a three-layer laminated paper in which 0.18 mm thick aramid paper / PET / aramid paper is adhered with a urethane adhesive is used. The length of the slot insulating paper 5 is 100 mm, and the slot insulating paper 5 protrudes 3 mm from both ends of the slot.

With the above insulation model as a common condition, in the examples, the surface of the flat enamel insulated wire was spray-coated with the following diluent to form a first resin layer.

The diluent is a mixture of 100 parts by mass of a phenol novolac type epoxy resin, which is a polyfunctional epoxy resin, 90 parts by mass of an acid anhydride-based curing agent, and 2 parts by mass of an imidazole-based curing accelerator, and is dissolved in acetone. It was produced by.

Therefore, in the simulated coil 4 of the embodiment, the first resin layer is formed on the surface of the flat enamel insulated wire. Here, the coating thickness of the first resin layer was set to about 0.05 mm.

Further, in order to completely fix the constituent material in the slot, a second resin layer was formed and subjected to a thermosetting treatment.

FIG. 4 is a cross-sectional view showing a part of the simulated coil of the embodiment.

In this figure, the state before the thermosetting treatment is shown. The copper conductor 11 is covered with a polyimide insulating layer 12, and the outside thereof is further covered with a first resin layer 13. The two adjacent copper conductors 11 are surrounded by a second resin layer 14. In other words, the second resin layer 14 is applied to the voids formed between the two adjacent copper conductors 11. The second resin layer 14 is provided at least at the corners (corners) of the two adjacent copper conductors 11. The first resin layer 13 covering each of the two copper conductors 11 is in contact with each other but has a boundary.

FIG. 5 is a cross-sectional view showing a part of the simulated coil of the embodiment after the thermosetting treatment.

In this figure, the first resin layer 13 in FIG. 4 is changed to the first cured resin layer 113, and the second resin layer 14 is changed to the second cured resin layer 114. In FIG. 5, the first resin layer 13 between the two copper conductors 11 is melted, thermoset, and integrated. Therefore, the boundary shown in FIG. 4 has disappeared. The second cured resin layer 114 is provided at least at a corner portion (corner portion) of two adjacent copper conductors 11.

By using the above-mentioned stator, it is possible to manufacture a rotary electric machine that can withstand a high driving voltage without increasing the thickness of the slot insulating paper.

Next, the resin composition used for forming the second resin layer will be described.

In Example 1, a resin composition prepared by mixing 100 parts by mass of a bisphenol A type epoxy resin with 80 parts by mass of an acid anhydride-based curing agent and 1 part by mass of an imidazole-based curing accelerator was prepared. A second resin layer was formed by pouring it into the voids of the constituent material in the slot. Then, it was thermoset and the constituent material in the slot was fixed.

In Example 2, a resin composition prepared by mixing 2 parts by mass of a peroxide-based curing agent having a half-temperature of 125 ° C. for 1 hour with 100 parts by mass of an unsaturated polyester resin was prepared in the same manner as in Example 1. , A second resin layer was formed by pouring into the voids of the constituent material in the slot. Then, it was thermoset and the constituent material in the slot was fixed.

(Comparison example)
In the comparative example, the configuration shown in FIGS. 2 and 3 was adopted in a state where the first resin layer was not formed, and the resin composition used for the second resin layer of Example 1 was used as a gap in the constituent material in the slot. A second resin layer was formed by pouring into. After that, it was thermoset to obtain an insulation model equivalent to the conventional technique.

The conditions for thermosetting in Examples and Comparative Examples were 160 ° C. × 1 hour. By this thermosetting treatment, the first resin layer and the second resin layer were cured at the same time.

Table 1 shows the configurations of the insulation models in Examples and Comparative Examples. Here, the resin material constituting the first resin layer is referred to as a first resin, and the resin material constituting the second resin layer is referred to as a second resin.

Next, the thermal deterioration of the fixed resin of the insulating model manufactured as an example and a comparative example will be described.

For the purpose of thermal deterioration of the fixed resin (cured resin product), heat treatment was performed at 220 ° C. for 960 hours, and the partial discharge start voltage before and after the thermal deterioration treatment was measured.

Table 2 shows the measurement results of the partial discharge start voltage. The numerical values in the table are shown by the average value of the partial discharge start voltage between each adjacent coil electric wire (3 sets / insulation model). The partial discharge start voltage was a voltage at which the amount of discharge charge reached 100 pC, and the applied voltage frequency was 50 Hz.

From Table 2, both Examples and Comparative Examples show the same partial discharge start voltage before thermal deterioration. Specifically, it is 1.89 to 2.02.

In Example 1, what was 1.95 before the heat deterioration became 1.97 after the heat deterioration.

In Example 2, what was 2.02 before the heat deterioration became 1.85 after the heat deterioration.

On the other hand, in the comparative example, what was 1.89 before the thermal deterioration decreased to 0.72 after the thermal deterioration.

Therefore, in Examples 1 and 2, the partial discharge start voltage does not decrease even after thermal deterioration, and the effect of the present invention can be confirmed. However, in the comparative example, it can be seen that the partial discharge start voltage drops significantly after thermal deterioration.

Here, when the insulation model after thermal deterioration was disassembled and the state of the fixed resin was observed, it was found that resin cracks were generated in the comparative example.

FIG. 6 is a perspective view schematically showing the state of the resin crack in the comparative example.

As shown in this figure, in the case of the comparative example, the copper conductor 11 is covered with the polyimide insulating layer 12, and the second cured resin layer 114 is formed in the gap formed between the two adjacent copper conductors 11. Has been done. Large resin cracks 15 are generated in the second cured resin layer 114.

The partial discharge start voltage after thermal deterioration in the comparative example is substantially equal to the partial discharge start voltage between the lines measured by a model (back-to-back model) in which the planes of two flat enamel insulated wires of the simulated coil are simply combined. Therefore, when the resin crack 15 generated in the comparative example reaches the polyimide insulating layer 12 of the simulated coil, it can be inferred that a gap connecting the adjacent simulated coils is formed and the state is equivalent to that of the back-to-back model.

From this, it is expected that if the thermal deterioration further progresses, the polyimide insulating layer 12 of the simulated coil will deteriorate, leading to dielectric breakdown at an early stage.

Similarly, when the insulation models of Examples 1 and 2 after thermal deterioration were disassembled and investigated, cracks were generated in the second resin layer as in the comparative example, but the degree was minor and the first It was confirmed that the crack growth stopped near the interface with the resin layer, and the effect of arranging the polyfunctional epoxy resin having high heat resistance as the fixing resin in the simulated coil corner portion as the first resin layer was confirmed.

By the way, in Examples 1 and 2, the materials used for forming the second resin layer are different. Therefore, as shown in Table 2, although there is no difference in the partial discharge start voltage after thermal deterioration, there is a possibility that the partial discharge start voltage will be morphologically different.

Therefore, the vicinity of the interface between the first cured resin layer and the second cured resin layer of Examples 1 and 2 was investigated in detail. As a result, it was found that in Example 1, a mixed layer of both resins was formed between the first cured resin layer and the second cured resin layer.

FIG. 7 shows a cross section including the above mixed layer.

As shown in this figure, in Example 1, the mixed layer 116 is formed between the first cured resin layer 113 and the second cured resin layer 114. The mixed layer 116 is a region in which the components of the first cured resin layer 113 and the components of the second cured resin layer 114 are mixed. In the case of Example 1, since both the first resin and the second resin are epoxy resins, they are easy to mix. The mixed layer 116 has a component close to the component of the first cured resin layer 113 in the portion in contact with the first cured resin layer 113, and the second cured resin in the portion in contact with the second cured resin layer 114. It has components close to those of layer 114. In other words, the mixed layer 116 has a concentration gradient. Therefore, the physical properties of the mixed layer 116 are smoothly changed. As a result, it is considered that the growth of cracks in the second cured resin layer 114 is further suppressed, and the partial discharge start voltage after thermal deterioration is maintained higher than in Example 2.

In the examples, a trifunctional phenol novolac type epoxy resin was used as the first resin, but a polyfunctional epoxy resin such as a cresol novolac type epoxy resin, a glycidyl amine type epoxy resin, or a glycidyl ether type epoxy resin could be used alone or. It is also possible to mix and apply. Further, a resin composition obtained by mixing a bifunctional epoxy resin such as bisphenol A type and the above-mentioned polyfunctional epoxy resin is also applicable.

In the present invention, an acid anhydride-based curing agent is used as the curing agent for the first resin, but a curing agent generally used as an epoxy resin curing agent such as amine-based, polyamide-based, and dicyandiamide can be applied. It is important to select a curing agent that can impart high heat resistance to the cured epoxy resin.

By the way, in the embodiment, the flat enamel insulated wire was separately coated with the first resin to produce an insulating model. However, when the stator of the actual machine is manufactured by the present invention, it is not a good idea to coat the coil with the first resin by the same method as in the embodiment in terms of manufacturing cost. Therefore, a method of forming a stator coil using a flat enamel insulated wire to which a resin for forming a first resin layer is previously applied is desirable as a method for manufacturing a stator.

FIG. 8 is a flow chart showing an example of a method for manufacturing a stator of an actual machine.

As shown in this figure, the segment coil (coil wire) used for the stator is molded (S101), and the segment coil (one coil wire) is coated with the first fixed varnish containing the first resin. (S102). Then, the slot insulating paper is inserted into the slot, and the segment coil (coil electric wire) is inserted into the space inside the slot insulating paper in the slot (S103). After that, the segment coil is bent (S104), and the segment coil is welded (S105). Then, a second fixing varnish containing the second resin is applied or impregnated into the segment coil (S106), and a thermosetting treatment is performed (S107).

Hereinafter, examples of a rotary electric machine and a stator will be described.

FIG. 9 is a cross-sectional view showing a rotary electric machine provided with the stator of the present invention.

In this figure, the rotary electric machine 200 includes a rotor 210, a stator 220, and a housing 251.

A stator 220 is fixed to the inner peripheral side of the housing 251. A rotor 210 is rotatably installed on the inner peripheral side of the stator 220. The housing 251 is formed into a cylindrical shape by cutting an iron-based material such as carbon steel, casting a cast steel or an aluminum alloy, or pressing, and constitutes an outer cover of an electric motor. The housing 251 is also referred to as a frame or frame.

A liquid-cooled jacket 230 is fixed to the outer peripheral side of the housing 251. A refrigerant passage 253 for a liquid refrigerant RF such as oil is provided between the inner peripheral wall of the liquid-cooled jacket 230 and the outer peripheral wall of the housing 251. The refrigerant passage 253 is formed so as not to leak liquid. The liquid-cooled jacket 230 houses bearings 244 and 245, and is also called a bearing bracket.

In the refrigerant RF, the liquid accumulated in the refrigerant (oil) storage space 250 passes through the refrigerant passage 253 and flows out from the refrigerant outlets 254 and 255 toward the stator 220 to cool the stator 220.

The stator 220 includes a stator core 232. The stator core 232 is a laminated thin plate of silicon steel plate. The stator core 232 is provided with a stator coil (reference numeral 260 in FIG. 10 described later). The stator coils are wound in a large number of slots provided on the inner peripheral portion of the stator core 232. The heat generated from the stator coil is transferred to the liquid-cooled jacket 230 via the stator core 232 and dissipated by the refrigerant RF circulating in the liquid-cooled jacket 230.

The rotor 210 is composed of a rotor core 212 and a shaft 213. The rotor core 212 has a structure in which thin plates of silicon steel plates are laminated. The shaft 213 is fixed to the center of the rotor core 212. The shaft 213 is rotatably supported by bearings 244 and 245 attached to the liquid-cooled jacket 230, and rotates at a predetermined position in the stator 220. Further, the rotor 210 has a permanent magnet 218. The rotor 210 rotates due to the magnetic action of the stator 220 that generates a rotating magnetic field.

A conductor 240 for neutral point connection is drawn out from one coil end 261 of the stator coil. The coil end 262 is welded.

The liquid-cooled jacket 230 is composed of an engine case, a transmission case, and the like.

The rotary electric machine 200 is a three-phase synchronous motor with a built-in permanent magnet. The rotary electric machine 200 operates as an electric machine for rotating the rotor 210 by supplying a three-phase AC current to the stator coil wound around the stator core 232. Further, when the rotary electric machine 200 is driven by an engine, it operates as a generator and outputs three-phase alternating current generated power. That is, the rotary electric machine 200 has both a function as an electric motor that generates rotational torque based on electric energy and a function as a generator that generates electric power based on mechanical energy, depending on the running state of the automobile. The above functions can be selectively used.

FIG. 10 is a perspective view showing a state before the stator is inserted into the housing.

In this figure, the housing 251 and the stator 220 of the rotary electric machine are shown.

The housing 251 is formed in a cylindrical shape by drawing a steel plate (high-strength steel plate or the like) having a thickness of about 2 to 5 mm. The housing 251 is provided with a plurality of flanges 315 for fixing the liquid-cooled jacket. The plurality of flanges 315 are provided on the peripheral edge of one end surface of the cylindrical housing 251 toward the outside in the radial direction.

The stator 220 has a stator coil 260 and a cylindrical stator core 232 to which the stator coil 260 is mounted.

The stator core 232 is a laminated thin plate (thickness of about 0.05 to 1.0 mm) of a silicon steel plate (electromagnetic steel plate). A welded portion 270 is provided on the outer peripheral portion of the cylindrical stator core 232 in parallel with the axial direction of the stator core 232. Since the welded portion 270 is formed in a semicircular weld groove provided in advance on the outer peripheral portion of the stator core 232, the welded portion 270 does not protrude outward in the radial direction of the stator core 232. The welded portion 270 is formed by TIG welding, laser welding, or the like.

The stator core 232 has a core back 342 and teeth 395.

In the stator coil 260, a total of 6 systems (U1, U2, V1, V2, W1, W2) of coils are mounted in close contact with the stator core 232. The six coils constituting the stator coil 260 are arranged by slots at appropriate intervals.

One coil end 340 of the stator coil 260 has AC terminals 391 (U), 392 (V), and 393 (W), which are coil conductors for input and output of the stator coil 260 of each of the three UVW phases. The conductor 240 for connecting the sex points is pulled out.

In order to improve workability in assembling the rotary electric machine, the AC terminals 391 (U), 392 (V), and 393 (W) are projected outward from the coil end 340 in the axial direction of the stator core 232. Have been placed. Then, AC power is supplied to the stator 220 by being connected to a power conversion device (not shown) via the AC terminals 391 (U), 392 (V), and 393 (W). There is.

The stator coil 260 has a structure in which the outer periphery of the conductor is covered with an insulating film, and electrical insulation is maintained. If the dielectric strength is maintained by the insulating paper 380 in addition to the insulating film, the reliability can be further improved.

The insulating paper 380 contributes to maintaining the required dielectric strength even if the insulating film is damaged or deteriorated.

As shown in FIG. 10, the stator core 232 is fitted and fixed to the inside of the housing 251 by shrink fitting. As a specific assembly method, for example, first, a housing 251 whose inner diameter has been expanded by thermal expansion by heating in advance is fitted into the stator core 232. Next, the housing 251 is cooled to shrink the inner diameter, and the outer peripheral portion of the stator core 232 is tightened by the heat shrinkage.

Hereinafter, the coil electric wire which is a component of the stator will be described.

FIG. 11 is a schematic cross-sectional view showing an example of the coil electric wire of the present invention.

As shown in this figure, the coil electric wire is formed by providing a polyimide insulating layer 12 on the surface of a substantially rectangular copper conductor 11 and applying a first resin layer 13 on the outside thereof. The corners of the copper conductor 11 usually have a curvature.

Before producing the coil wire shown in this figure and performing the thermosetting treatment, it is wrapped in insulating paper and inserted into the slot of the stator core, and the second resin is poured into the gap in the slot, and then the thermosetting treatment is performed. By applying, the constituent materials in the slot are fixed. The coil wire is a component for that purpose. In other words, the coil electric wire is obtained by applying a first uncured resin (resin composition) to the surface of a flat enamel insulated wire.

By preparing a coil wire as shown in this figure in advance, cutting it to the required length, and using it, a part of the process in manufacturing the stator is performed externally, and the first resin is applied immediately before assembly. The step can be omitted.

1: Core, 2: Slot, 4: Simulated coil, 5: Slot insulating paper, 11: Copper conductor, 12: Polyimide insulating layer, 13: First resin layer, 14: Second resin layer, 15: Resin crack , 113: 1st cured resin layer, 114: 2nd cured resin layer, 116: mixed layer, 200: rotary electric machine, 210: rotor, 220: stator.

Claims (6)

With a core with a core back and teeth,
A conductor coated with an insulating layer and an electric wire containing a first resin covering the outer surface of the insulating layer are provided.
The wire has curved corners and has
The insulating layer is made of polyimide.
Wherein at least the angle portion of the wire adjacent one of the outer surface of the segment coils is a bundle of wires, the second resin is provided et al is,
The first resin is a polyfunctional epoxy resin.
The second resin is a stator , which is a bifunctional epoxy resin or an unsaturated polyester resin. A claim 1 Symbol mounting of the stator,
A stator in which a mixed layer containing the first resin and the second resin is formed between the first resin and the second resin. The stator according to claim 1 or 2.
The conductor is a stator having a substantially rectangular cross section. A rotary electric machine comprising the stator and rotor according to any one of claims 1 to 3. The method for manufacturing a stator according to any one of claims 1 to 3.
The step of inserting the electric wire into the slot formed between the teeth, and
A method for manufacturing a stator, which comprises a step of providing the second resin at least at the corners of adjacent electric wires. The method for manufacturing a rotary electric machine according to claim 4.
A step of inserting the electric wire into a slot formed between the teeth constituting the core of the stator, and
A method for manufacturing a rotary electric machine, which comprises a step of providing the second resin at least at the corners of adjacent electric wires.

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