WO2010086997A1

WO2010086997A1 - Stator and motor

Info

Publication number: WO2010086997A1
Application number: PCT/JP2009/051591
Authority: WO
Inventors: 竹内誉人
Original assignee: トヨタ自動車株式会社
Priority date: 2009-01-30
Filing date: 2009-01-30
Publication date: 2010-08-05

Abstract

Disclosed is a stator in which an insulator superior in crack resistance is integrally formed around teeth while it is superior in radiation property and is thin as much as possible by setting securing of insulation property as assumption. Also disclosed is a motor having the stator. The stator (division core (10)) is formed of a yoke (12) whose plane view is in an almost circular shape, the teeth (11) projected inward in a radial direction from the yoke (12), and a slot formed between the adjacent teeth (11) and (11). The integrally formed insulator (20) is arranged at a periphery of a side (11') confronted with the slot of the teeth (11) and a top face (11”) which is not confronted with the slot. A concave groove (11a) extending in a height direction of the teeth (11) is formed in a root part (X2) of the teeth (11). A projected bar (20a) of the insulator (20) is formed inside the concave groove (11a).

Description

Stator and motor

The present invention relates to a stator including an insulator formed integrally around at least a tooth, and a motor including the stator.

In the automobile industry, with the aim of further improving the running performance of hybrid cars and electric cars, developments for drive motors with higher output, lighter weight, and smaller size are being made every day. In addition, home appliance manufacturers have no choice but to develop further miniaturization and higher performance of motors incorporated in various home appliances.

The stator core constituting the motor (electric motor) is generally composed of the following two forms. One of them is formed from a steel plate laminate in which steel plates each having an annular yoke, a plurality of teeth projecting radially inward from the yoke, and a slot formed between adjacent teeth are laminated. Is. The other is to form a stator core from a powder magnetic core obtained by pressure-molding magnetic powder, a high-density powder magnetic core (HDMC), or the like.

In the above-described stator core, for example, a coil in which an enamel insulating film is formed around a copper conductive wire is wound around a tooth while being inserted into a slot defined between the teeth. ing. Here, there are a concentrated winding method and a distributed winding method for winding the conductive wire for the coil. Of these, the concentrated winding method is a form in which a conductive wire is wound for each tooth, and the distributed winding method is a form in which a conductive wire is wound across a plurality of teeth. Distributed winding coils are generally applied. In either concentrated winding or distributed winding, slot insulating paper is interposed between them from the viewpoint of ensuring insulation between the slot surface of the stator core and the coil. However, when the insulation paper is used to insulate the coil and the core, it cannot be avoided that an air layer (air gap) is formed between the insulation paper and the core. In order to increase it, it becomes a big cause to reduce the heat dissipation to the core of Joule heat generated in the coil when the motor is driven.

Therefore, by forming the insulator by integrally molding the resin of the insulating material around the teeth, for example, measures can be taken to ensure the adhesion between the insulator and the core and not to form an air layer between the two. is there. A split stator core in which an insulator is formed by this integral molding is disclosed in Patent Document 1, and in this split stator core, a guide groove for guiding a coil is provided on the teeth base end side of the yoke.

From the viewpoint of miniaturization of the motor and heat dissipation, the integrally molded insulator described above is preferably as thin as possible on the premise of ensuring insulation, but for example, in order to improve heat dissipation, If an insulator is to be injection-molded, filling failure (resin fluidity failure) at the time of injection molding is likely to be difficult to mold. Regarding the poor fluidity, the problem of poor fluidity becomes more conspicuous when the resin contains an inorganic filler in order to improve heat dissipation. Furthermore, not only the integrally molded insulator but also the insulator that is molded separately and fitted to the teeth in a later process, the linear expansion coefficient of the resin insulator is naturally higher than that of the stator core. Therefore, there is a problem that cracks due to temperature stress are likely to occur depending on the use environment. For example, the linear expansion coefficient of iron is about 12 × 10 ⁻⁶ / ° C., whereas the linear expansion coefficient of polystyrene (PS) or polyphenylene ether (PPE) is about 60 × 10 ⁻⁶ / ° C., polypropylene. The linear expansion coefficient of (PP) is about 100 × 10 ⁻⁶ / ° C., which is considerably higher than that of iron (including magnetic steel sheets). Therefore, the amount of deformation during temperature change ( (Expansion amount, contraction amount) are greatly different.

With regard to this crack, according to the knowledge of the present inventors, in a general cylindrical insulator, deformation of the insulator is constrained at the corner portion, and in the central portion (for example, the portion corresponding to the central portion of the tooth side surface) Since the amount of deformation is relatively large, the temperature stress increases in the vicinity of the corner portion of the insulator, more specifically, the portion slightly entering the central portion from the corner portion, and the protruding direction of the teeth. It has been specified that cracks extending in the (radial direction) are likely to occur in this insulator region.

This will be described with reference to FIG. FIG. 7 shows an insulator b integrally formed around a tooth a1 of a split core a (consisting of a steel plate laminate of electromagnetic steel plates a ′) forming a split stator core and a surface facing the slot s of the yoke a2. Shows things. In the same figure, the insulator b around the teeth is formed of a side surface b1 facing the slot s and a top surface b2 not facing the slot s, and the corner portion G composed of the side surface b1 and the top surface b2 It is highly rigid compared with the part. Therefore, when the illustrated split core a is assembled to form a split stator core, when a motor including the split core undergoes a cooling cycle between a high temperature atmosphere during driving and a low temperature or normal temperature atmosphere during non-driving. Is a crack c extending in the radial direction in the vicinity of the corner G of the side surface b1 of the insulator b. In addition, according to the present inventors, when analyzing the temperature stress at the time of this thermal cycle, it has been specified that relatively large temperature stress is generated in this corner portion and its vicinity, Correlate with the cracks that occur.

In this way, when forming an insulator by integrally molding a resin around the teeth, a material that satisfies all the elements of high thermal conductivity, good filling based on high fluidity, and high strength (crack resistance) at the same time Since the approach from the aspect is extremely difficult, it is one of the urgent issues in the technical field to effectively solve all of these problems by the approach from the structural aspect of the stator. . Note that even the split stator core disclosed in Patent Document 1 cannot effectively solve all of the above problems.
JP-A-11-332138

The present invention has been made in view of the above-mentioned problems, and an insulator excellent in heat resistance and as thin as possible on the premise of ensuring insulation, is integrally molded around the teeth while being excellent in crack resistance. An object of the present invention is to provide a stator and a motor including the stator.

In order to achieve the above object, a stator according to the present invention is a stator comprising a substantially annular yoke in plan view, teeth projecting radially inward from the yoke, and slots defined between adjacent teeth. An insulator formed integrally is provided at least around the side surface facing the slot of the tooth and the top surface not facing the slot, and the tooth is provided from the radial tip to the yoke. The width of the teeth increases toward the root portion to be connected, and a groove extending in the height direction of the tooth is formed in the root portion of the tooth, and the protrusion of the insulator is formed in the groove. It is what.

In the stator according to the present invention, the insulator is integrally formed by injection molding or the like around at least the teeth, and the width of the teeth increases from the radial tip to the root connected to the yoke. In the present invention, a groove extending in the height direction of the tooth is formed in the root portion of the tooth, and the protrusion of the insulator is formed in the groove, so that the tooth is moved in the height direction. This is a stator that can be reinforced with the protrusions and can effectively suppress the occurrence of cracks that may occur in the vicinity of the corners. Furthermore, since the above-mentioned concave groove is formed at the root of the tooth, this concave groove becomes a resin flow path at the time of injection molding, so that sufficient resin flow is compensated by this concave groove. The stator is capable of forming a thin-layer insulator around the teeth.

Here, the “root portion” is a portion connected to the yoke in the tooth, and the portion where the groove is formed is the root portion and either one or both sides of the tooth. However, it suffices if a groove is formed in the root portion, and it is not excluded that a groove is formed in a tooth portion other than this.

According to the present inventors, in a form in which the width of the teeth increases from the radial tip to the root connected to the yoke, a concave groove bulging inside the teeth is provided, for example, on both sides of the root. Even so, it has been demonstrated that the torque reduction rate of the motor including the stator having the teeth is extremely small. In other words, heat dissipation performance can be improved by integrally forming a thin insulator while minimizing the reduction rate of torque that can be reduced by providing grooves in the teeth as much as possible. The crack resistance of the insulator can be improved by the protrusion of the insulator that is filled and hardened inside. In addition, in the form in which the insulator is fitted to the teeth in a later process, it is extremely difficult to form the protrusions of the insulator (for example, to fit) in the concave groove at the root of the teeth (when fitting). Insulator breaks or cracks occur), the tooth has a groove at its root, and the insulator is integrally formed to automatically form a protrusion in the groove. There is an extremely high phase from the viewpoint of manufacturability and manufacturability.

In addition to the stator integrally formed in an annular shape, the stator described above has a split core composed of an arc-shaped yoke in plan view and teeth projecting radially inward from the yoke in the circumferential direction. The outer periphery includes both divided stators that are fastened by, for example, a cylindrical body. Furthermore, in addition to those formed from a steel sheet laminate formed by laminating electromagnetic steel sheets, those formed from a powder magnetic core, a high-density powder magnetic core (HDMC), etc. formed by pressure-forming magnetic powder are included. Here, as the magnetic powder, iron, iron-silicon alloy, iron-nitrogen alloy, iron-nickel alloy, iron-carbon alloy, iron-boron alloy, iron-cobalt alloy, iron-phosphorus Examples thereof include soft magnetic metal powders such as iron alloys, iron-nickel-cobalt alloys and iron-aluminum-silicon alloys, or soft magnetic metal oxide powders coated with a resin binder such as a silicone resin.

Therefore, the groove formed in the root portion of the stator core is formed with a notch (concave groove) having a desired shape and size in the root portion of each steel plate when the stator core is made of a steel plate laminate. Thus, a concave groove having a desired planar shape and planar dimension can be formed in the height direction of the teeth. Also, when the stator core consists of a dust core, the base of the teeth is automatically formed when the mold is opened by pressing and forming the grooves on the cavity side of the mold. A groove having a desired shape and size can be formed by, for example, a method of cutting after pressure molding.

The above-mentioned concave groove is formed in the root portion of the tooth, and the insulator is provided with a protrusion (rib) formed in the concave groove, whereby the molded insulator has the protrusion extending in the height direction. By the high-rigidity part which consists of the corner part (corner part formed by the slot side side and top face of teeth) of the both ends, and the ridge which connects these corner parts, The crack resistance of the inner side is greatly improved. It should be noted that an insulator having a conventional structure constitutes the stator of the present invention, whereas when it is thermally expanded or contracted, high temperature stress sites are likely to concentrate only at the corners at both ends, and cracks are likely to occur. Insulators also generate relatively large temperature stresses in high-rigidity parts reinforced with ridges, and this also has the effect of dispersing and mitigating temperature stresses that tend to concentrate at the corners at both ends. From this viewpoint, the crack resistance is improved.

Therefore, in the insulator that constitutes the stator of the present invention, the problem that occurred in the case of the conventional insulator having no protrusion described above, that is, excessive temperature stress is generated at the corners at both ends, resulting in this. Thus, the problem of cracking is effectively eliminated.

Further, the insulator to be injection-molded is preferably molded not only on the teeth but also on the surface facing the slot of the yoke. In this case, in the injection molding, the surface around the teeth and the surface facing the slot of the yoke are preferably formed. The insulator is molded simultaneously and integrally.

Further, it is desirable that the above-mentioned concave groove is formed outside the tooth with respect to the projected portion when the radial tip portion of the tooth is projected onto the root portion. If the concave groove is formed to the inside of the teeth from the projected portion, the flow of magnetic flux from the teeth to the yoke is obstructed, and the torque performance of the motor equipped with this stator is greatly reduced. is there. Further, from the verification by the present inventors, it is desirable that the concave groove is formed only in the teeth, and therefore the concave groove is not formed from the root portion of the tooth to the yoke.

Further, in addition to the above-described concave groove, a concave groove extending in the radial direction is further formed on the side surface facing the slot of the tooth, and a separate ridge of the insulator is also formed in the concave groove. Form may be sufficient. This is because the insulator has a ridge extending in the height direction of the teeth and a ridge extending perpendicularly to the teeth in the radial direction, and the high rigidity portion is further increased. The rigidity is further increased.

At least after the insulator is formed around the teeth, the coil of the present invention is formed by concentrated winding or distributed winding. Here, in order to increase the space factor of the coil, a rectangular wire including a rectangular conductor having a substantially rectangular cross-sectional view and an insulating film formed on the outer periphery of the rectangular conductor is wound around the insulator. Is preferred.

According to the stator of the present invention, the insulator is integrally formed at least around the teeth by injection molding or the like, so that the air gap that may be generated between the core and the insulator is in close contact with each other, and the coil to the core is removed. Heat dissipation performance can be improved. In addition, even in the case where there is a large linear expansion coefficient divergence between the core and the insulator in the cooling cycle of the motor, the insulator is reinforced by a highly rigid protrusion that extends in the height direction. Generation of cracks that can occur can be effectively avoided. In addition, since a groove extending in the height direction is formed at the root of the teeth, this promotes the resin flow and allows the resin to be spread all around the teeth. Insulating thin layers of insulators can be integrally formed, so that an insulator with extremely high heat dissipation performance can be formed. In addition, since the flow is compensated by the resin flow promoting effect by the concave groove even when the inorganic filler described above is contained in the resin to be used, the improvement of the heat radiation performance due to the inclusion of the inorganic filler is also expected. Is possible.

A motor comprising the above-described stator of the present invention and a rotor rotatably disposed in the stator is such that the insulator formed around the teeth is as thin as possible, and the insulator and the core are in close contact with each other. In addition, the insulator does not crack or is hardly cracked, and the motor is as small as possible, excellent in heat dissipation, and excellent in crack resistance (or durability). Therefore, the motor including the stator according to the present invention has been recently produced, and a hybrid vehicle and an electric vehicle that require further compactness, high durability, and high heat dissipation especially for a drive motor mounted on a vehicle. It is suitable for.

As can be understood from the above description, according to the stator of the present invention and the motor including the stator, the stator as small as possible, excellent in heat dissipation, and excellent in crack resistance (or durability) A motor having this can be obtained.

It is the perspective view which showed the split core which consists of a steel plate laminated body. It is the perspective view which showed the division | segmentation core in which the resin integral molding insulator was formed in the side of the slot side of a yoke circumference and a yoke. FIG. 3 is a view taken in the direction of arrows III-III in FIG. 2. (A) is the schematic diagram of the ditch | groove and protrusion shown in FIG. 2, (b), (c) is the schematic diagram which showed other embodiment of the ditch | groove and protrusion. It is the perspective view which showed the motor which consists of the stator by which the division | segmentation core shown in FIG. 2 was assembled | attached to the circumferential direction, and a rotor. It is the figure which showed the result (magnetic flux density contour) of the magnetic field analysis, (a) is the result of the comparative example 1, (b) is the result of the comparative example 2, (c) is the result of the comparative example 3. Yes, (d) is the result of the example. It is the schematic diagram explaining the state which the crack has arisen in the conventional division | segmentation core in which the resin integral molding insulator was formed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electromagnetic steel plate, 10 ... Divided core, 11 ... Teeth, 11 '... Side surface which opposes slot of teeth, 11 "... Top surface which does not oppose slot of teeth, 11a, 11b, 11c ... Groove, 20 ... Resin integral Molded insulators, 20a, 20b, 20c ... ridges, 21 ... side faces facing the slots of the insulators, 22 ... top faces not facing the slots of the insulators, 23 ... side faces facing the slots of the insulators, 100 ... stators, 200 ... rotors , 300 ... Permanent magnet, X1 ... Radial tip, X2 ... Root, G ... Corner

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Although the illustrated example shows a split core, it is needless to say that a general stator integrally formed in an annular shape may be used. In the illustrated example, the coil formed around the teeth is not shown, but this coil may be either a flat wire or a general cross-section coil. However, it is preferable to apply a rectangular wire from the viewpoint of the space factor. Further, the illustrated example shows a concave groove extending in the height direction of the tooth and a protrusion of the insulator formed in the concave groove. In addition to the concave groove and the protrusion, the groove faces the tooth slot. A concave groove extending in the radial direction may be further formed on the side surface, and a protrusion of a separate insulator may be formed in the concave groove.

FIG. 1 shows a split core 10 constituting a split stator of an IPM motor. The split core 10 includes a yoke 12 having a substantially arc shape in plan view and a tooth 11 protruding radially inward from the yoke 12 and is formed by laminating electromagnetic steel plates 1. In addition to the form in which the electromagnetic steel plates are laminated as shown in the illustrated example, it may be formed from a dust core, a high-density dust core (HDMC), or the like.

The teeth 11 of the split core 10 have a width that increases from the radial tip end portion X1 toward the root portion X2 connected to the yoke 12, and project on the both sides of the root portion X2 to the inside of the teeth 11.

Grooves

11a and 11a extending in the height direction of the teeth 11 are formed. The concave groove 11a is formed by forming a notch (concave groove) having a desired shape and size in the root portion X2 of each electromagnetic steel sheet 1 to thereby form the concave groove 11a having a desired planar shape and planar dimension. Can be formed in the height direction of the teeth.

FIG. 2 shows the divided core 10 shown in FIG. 1 around the teeth 11 (the side surface 11 ′ facing the tooth slot and the top surface 11 ″ not facing the tooth slot) and the side surface 12 ′ of the yoke 12 on the slot side. The state in which the resin integrated molded insulator 20 is formed is shown.

The insulator 20 accommodates the split core 10 in a mold (not shown) and injection-molds an appropriate thermosetting resin or thermoplastic resin into the mold, thereby forming the periphery of the teeth 11 and the side surface 12 ′ of the yoke 12. Specifically, the side surface 21 facing the slot of the insulator 20 on the outer periphery of the side surface 11 ′ facing the slot forming the tooth 11 is formed on the top surface 11 not facing the slot of the tooth 11. The top surface 22 that does not oppose the slot of the insulator 20 is formed on the outer periphery of the insulator 20, and the side surface 23 that opposes the slot of the insulator 20 is formed on the side surface 12 ′ that opposes the slot of the yoke 12.

In this injection molding, the injection resin is also filled into the concave groove 11a, and is cured to form a protrusion 20a having a shape and dimensions (cross-sectional rigidity) corresponding to the concave groove 11a.

In this injection molding, the concave groove 11a also serves as a resin flow path, and the resin filled in a molding die (not shown) flows in the height direction of the tooth 11 through the concave groove 11a. At a certain level, it can flow into the space between the cavity surface of the mold and the side surfaces of the teeth 11 and the yoke 12. Therefore, even when this space is narrow (and therefore the thickness of the insulator 20 is thin), the resin can be effectively distributed over the entire surface of the insulator 20, so that the thin-layer insulator 20 can be molded. Become.

In FIG. 2, the insulator 20 has a corner portion G and a ridge 20a that are higher in rigidity than other parts (side surface 21 and top surface 22). Compared with the insulator of the conventional structure which does not exist, the whole rigidity is remarkably high. As a result, the occurrence of cracks in the vicinity of the corner G as shown in FIG. It is to be noted that the presence of the high-rigid protrusions 20a alleviates the concentration of excessive temperature stress only in the vicinity of the corner portion G, so that the occurrence of the cracks is suppressed.

Actually, after the insulator 20 is formed into the split core 10, for example, a coil made of a rectangular wire (not shown) is formed around the teeth 11 (the surrounding insulator 20), and the split core 10 on which the coil is formed is formed. The split stator is formed by being assembled in the circumferential direction, and by further inserting the split core assembly unit into the nonmagnetic material cylinder and performing shrink fitting.

FIG. 3 is a view taken in the direction of arrows III-III in FIG. 2, and is a diagram illustrating in more detail the site where the protrusion 20a is formed in a plan view.

In the same figure, the formation part of the protrusion 20a (or the concave groove 11a) is a region A outside the tooth 11 with respect to the projection part when the radial tip part X1 of the tooth 11 is projected onto the root part X2. By forming the concave groove 11a and the protrusion 20a in the outer region A, the flow of magnetic flux flowing from the tooth 11 to the yoke 12 is minimized as much as possible. The torque reduction rate that can be reduced by forming the teeth 11 on the teeth 11 can be minimized.

That is, according to the split core 10, the following effects can be expected by providing the concave groove 11a while minimizing the reduction rate of the motor torque when the concave groove 11a is formed. That is, it is formed in the concave groove 11a, such as ensuring the effective fluidity of the resin for integral molding, ensuring the moldability of the thin-layer integrally molded insulator resulting from this, and improving the heat dissipation performance resulting from this. This is an effect that the crack resistance of the insulator 20 is improved (durability is improved) by the protrusion 20a.

FIG. 4 is a schematic diagram showing various embodiments of the groove and the protrusion. Specifically, FIG. 4a shows a schematic diagram of the groove and protrusion shown in FIG. 2, and FIGS. 4b and 4c are schematic diagrams showing other embodiments.

FIG. 4a shows a ridge 20a corresponding to the shape and size of the groove 11a protruding into the tooth 11 in a triangular shape. On the other hand, in FIG. 4b, the groove 11b has a rectangular shape in plan view, and in FIG. 4c, the groove 11b having a rectangular shape in plan view is provided at the root portion X2, and a rectangular shape in plan view is separately provided at a midway position in the radial direction of the tooth 11. The protrusion 20c is provided. Thus, the shape of the grooves and ridges to be formed, and their radixes are not particularly limited, and are formed at least in the outer region A, and at least the root groove X2 of the teeth 11 and the grooves What has a protrusion is sufficient.

FIG. 5 is a perspective view showing an IPM motor including a stator in which the divided cores shown in FIG. 2 are assembled in the circumferential direction and a rotor.

Specifically, the stator 100 in which the split cores 10 are assembled in the circumferential direction, and the rotor 200 that is rotatably disposed inside the stator 100 and is formed by stacking disc-shaped electromagnetic steel plates. It is roughly structured. In the rotor 200, a rotor shaft 210 (drive shaft slot) is opened at the center position, and a magnet slot extending in a direction along the rotor shaft 210 in a predetermined number is opened in the peripheral portion. The permanent magnet 300 is inserted into the magnet slot and, for example, a fixing resin is filled between the slot and the permanent magnet 300 to compensate for the fixing of the permanent magnet 300 in the slot.

[Magnetic field analysis and results for Examples and Comparative Examples]
The inventors conducted a magnetic field analysis under the following conditions, and verified the degree of reduction of the magnetic flux density when the concave groove was provided at the root of the tooth as in the stator of the present invention.

First, a unit model of a stator and rotor (V-shaped permanent magnet embedded type) as shown in FIG. 6 is created in a computer, current value: 114 (A), advance angle: 38 (degrees), and rotation speed: 1000 (rpm), permanent magnet residual magnetic flux density (Br): 1.17 (T), recoil relative magnetic permeability: 1.05 (μr), a laminate of electromagnetic steel sheets having a thickness of 0.3 mm for both the stator core and the rotor core The analysis was performed as formed from

Here, the analysis model of Comparative Example 1 has a tooth (there is no groove at the base portion) whose width increases from the radial tip portion toward the root portion connected to the yoke, and the analysis model of Comparative Example 2 Has a tooth whose width is constant from the radial tip to the root connected to the yoke (no groove in the root), and the analysis model of Comparative Example 3 is connected from the radial tip to the yoke. Teeth whose width increases toward the root part, in which a relatively large concave groove is formed from the root part of the tooth to the yoke, the model of the embodiment is a concave as shown in FIG. It has a groove at the base of the tooth. The results of the magnetic field analysis are shown in FIG. 6 and Table 1 below. In Table 1, the torque reduction rates of Comparative Examples 2 to 3 and Examples are compared to the torque of Comparative Example 1 as a reference. Show.

It has been found that magnetic steel sheets tend to magnetically saturate at 1.5 T (Tesla), and therefore tend to have lower magnetic permeability at 1.5 T or higher. That is, the magnetic saturation causes the flux (magnetism) from the stator to be reduced at the same current, and as a result, the torque is reduced. Therefore, in the contour diagram of the magnetic flux density of the analysis result of FIG. 6, the region of 1.5 (T) or more is a magnetic saturation region, which is a region contributing to a reduction in motor torque.

From the results of FIG. 6 and Table 1, compared to the comparative example 1 as a reference, the comparative example 2 in which the width of the teeth is constant reduces the torque by about 5%, changes the tooth width, and extends from the root portion to the yoke. In Comparative Example 3 in which a large concave groove was provided, it was specified that the torque was reduced by about 11%. Therefore, first, it is preferable that the width of the teeth is increased from the radial front end portion toward the root portion connected to the yoke, and the groove formed in the root portion of the teeth does not extend to the yoke. It has proven to be preferable.

On the other hand, compared with the comparative examples 2 and 3, the example is only 0.4% of torque reduction, and even when the groove is provided in the tooth, the groove forming portion is the root in the tooth. It is demonstrated that the motor torque can be reduced to a very small value when the size of the groove is such that the size of the groove does not hinder the flow of magnetic flux (for example, in the outer region A in FIG. 3). It was done.

Therefore, by providing the grooves shown in FIG. 3 etc. in the teeth and forming an integrally molded insulator around the teeth, the resin flow can be promoted by using the grooves while minimizing torque reduction. In particular, a thin-layer insulator can be formed, and high heat dissipation from the coil to the stator core via the insulator can be compensated.

[Cooling test and results]
The present inventors further prepared a stator 100 composed of the split core 10 with an insulator shown in FIG. 2 as an example, and a conventional structure in which the concave grooves 11a and the protrusions 20a were eliminated from the split core 10 shown in FIG. As a comparative example, a stator composed of a split core of the above is used as a comparative example. Temperature condition in a simulated cold region: −40 ° C., for example, a temperature condition assumed when a motor is driven and a maximum current is applied (maximum heat generation): 160 ° C. Until the occurrence of cracks (or growth of cracks) in which insulation could not be ensured was measured.

In each of the examples and comparative examples, five test specimens were easily prepared, and a total of five thermal tests were performed on each specimen to obtain an average.

As a result of the experiment, in the comparative example, it is measured 50 times, 50 times, 50 times, 100 times, and 300 times in order from the first time to the fifth time, and the average number of repetitions until the occurrence of a crack in which insulation cannot be secured is 110 times. Met.

On the other hand, in the examples, from the first time to the fifth time, the measurement is 100 times, 100 times, 100 times, 300 times, and 300 times in order, and the average number of repetitions until the occurrence of a crack in which insulation cannot be secured is 180 times. It was demonstrated that the number of repetitions can be improved by 60% or more as compared with the comparative example.

From the results of this experiment, as in the present invention, a groove is provided in the root of the tooth, and the protrusion of the insulator integrally formed in the groove is formed to reinforce the entire insulator, thereby providing crack resistance. It has been found that this is significantly improved as compared with an integrally molded insulator having a conventional structure.

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

Claims

A stator comprising a substantially annular yoke in plan view, teeth projecting radially inward from the yoke, and slots defined between adjacent teeth,
At least around the side surface facing the slot of the tooth and the top surface not facing the slot, an integrally molded insulator is provided,
The teeth have a larger width from the radial tip toward the root connected to the yoke,
A stator in which a groove extending in the height direction of the tooth is formed in the root portion of the tooth, and a protrusion of the insulator is formed in the groove.
A split core is formed from a yoke having an arc shape in plan view and teeth projecting radially inward from the yoke, and the split core is assembled in the circumferential direction to define a slot between adjacent teeth. A stator,
At least around the side surface facing the slot of the tooth and the top surface not facing the slot, an integrally molded insulator is provided,
The teeth have a larger width from the radial tip toward the root connected to the yoke,
A stator in which a groove extending in the height direction of the tooth is formed in the root portion of the tooth, and a protrusion of the insulator is formed in the groove.
3. The stator according to claim 1, wherein the concave groove is formed on an outer side of the tooth with respect to a projected portion when the radial tip portion of the tooth is projected on the root portion.
A rectangular wire comprising a rectangular conductor having a substantially rectangular cross-sectional view and an insulating film formed on an outer periphery of the rectangular conductor is wound around the insulator around the teeth. The stator according to any one of the above.
A motor comprising the stator according to any one of claims 1 to 4 and a rotor rotating inside the stator.