JP2010178520A - Stator and motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stator, along with a motor equipped with the stator, in which an insulator that is excellent in heat radiation property and excellent in anti-cracking property, being a thinnest layer to assure insulation property, is integrally molded around teeth. <P>SOLUTION: The stator (split core 10) includes yoke 12 which is annular in top view, teeth 11 protruding inward in radial direction from the yoke 12, and a slot defined between adjoining teeth 11 and 11. At least around a side surface 11' facing the slot of the teeth 11 and a top surface 11'' not facing the slot, an insulator 20 that is integrally molded is provided. A groove 11a extending radially is formed on the side surface 11' facing the slot of the teeth 11, and a ridge 21a of the insulator is formed in the groove 11a. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  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 driving motors with higher output, lighter weight, and smaller size are in progress 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.

  In general, a stator core constituting a motor (electric motor) has the following two formation modes. 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 is 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. In addition, 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 ( The amount of expansion and contraction is 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. 5 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, the divided core a shown in the figure is assembled to form a divided stator core, and the motor including the same is subjected to a thermal cycle between a high temperature atmosphere during driving and a non-driving time (for example, in a cold region). In this case, a crack c extending in the radial direction is generated in the vicinity of the corner portion G on 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 around at least the side surface facing the slot of the tooth and the top surface not facing the slot, and the side surface facing the slot of the tooth includes A groove extending in the radial direction is formed, and the protrusion of the insulator is formed in the groove.

  In the stator of the present invention, the insulator is integrally formed by injection molding or the like around at least the teeth, and a concave groove extending in the radial direction is formed on a side surface facing the slot of the teeth. Since the protrusion of the insulator is formed in the concave groove, the corner of the insulator and the rib (rib) shorten the unrestrained region span of the insulator, thereby causing excessive stress in the corner. It is a stator that can effectively prevent the occurrence of cracks by concentrating the cracks.

  Here, the concave groove is formed on the side surface facing the slot of the tooth, or one or two or more, and one concave groove is a single continuous concave groove in the longitudinal direction. Alternatively, it may be a concave groove extending intermittently in the longitudinal direction. In addition, “a groove extending in the radial direction” means a groove extending in parallel to the radial direction (a groove extending in a direction perpendicular to the rotation axis of the rotor disposed in the teeth), as well as from the parallel. It is meant to include a concave groove in a slightly inclined direction (a direction inclined toward the top surface side of the stator). Since the insulator is integrally formed by injection molding or the like, the resin is filled and cured in the above-described concave groove at the time of injection molding, and the shape and dimension (cross-sectional rigidity) corresponding to the concave groove are projected. Articles will be formed.

  In addition to the stator core integrally formed in an annular shape, the stator core is assembled with a split core composed of an arc-shaped yoke and teeth projecting radially inward from the yoke in the circumferential direction, and the outer periphery of the stator core is a cylindrical body. It includes both of the divided stator cores that are fastened together. 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 silicone resin.

  Therefore, the concave groove formed on the side surface of the stator core has a desired groove depth by making the steel plate width of the teeth where the concave groove is formed small as desired when the stator core is made of a steel plate laminate. Can be formed. When the stator core is made of a powder magnetic core, a groove for forming a concave groove is provided on the side surface of the cavity of the mold so that it is automatically recessed on the side surface of the tooth when the mold is pressed and opened. A desired number of concave grooves can be formed in a desired shape by a method of forming a groove or a method of cutting after pressure forming.

  The above-mentioned concave groove is formed on the side surface of the teeth on the slot side, and the insulator is provided with a protrusion (rib) formed in the concave groove, so that the insulator to be molded is In addition to the corners at the ends (the corners formed by the side surface and the top surface of the teeth on the slot side), a high-rigidity portion reinforced by one or more protrusions is provided. In this structure, since the insulator is divided into a plurality of spans at the reinforcing portions between the corners at both ends, if the insulator expands due to a temperature change, the high temperature stress part is at the corners at both ends. As a result, the temperature stress at the corners is also alleviated.

  Therefore, the problem that has occurred in the case of an insulator having a conventional structure in which the above-described reinforcing member does not exist, that is, the problem that an excessive temperature stress is generated at the corners of both ends and a crack is caused due to this, is effective. It will be resolved. Actually, the deformation of the insulator is defined by the span between the corner and the ridge, and the span between the ridge and the ridge, which are shorter than the span length between the two corners. As a result, the amount of linear expansion determined by the linear expansion coefficient and the length of the linear expansion span becomes smaller, resulting in the occurrence of cracks that can occur in the insulator itself even if there is a difference in the linear expansion coefficient between the insulator and the core. Is deterred.

  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.

  After the insulator is formed at least around the teeth, the stator of the present invention is formed by forming the coil 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, in the cooling cycle of the motor, even when there is a large linear expansion coefficient divergence between the core and the insulator, one or more protrusions (high rigidity portion) are formed at a desired portion of the insulator, It is possible to prevent the temperature stress from concentrating only on the corners of the insulator and to disperse the stress, thereby effectively avoiding the occurrence of cracks that may occur in the insulator.

  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. It is the III-III arrow line view of FIG. 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 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.

  Embodiments of the present invention will be described below 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. Further, 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 coil with a circular cross section. From the viewpoint of the space factor, it is preferable to apply a rectangular wire.

  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 side surface of the teeth of the split core 10, more specifically, the side surface 11 ′ facing the slot defined between the teeth when the split cores 10 are assembled in the circumferential direction, extends in the radial direction. A concave groove 11a is formed, and in the illustrated example, three concave grooves 11a are formed at a predetermined interval.

  FIG. 2 shows a state in which the resin-integrated insulator 20 is formed around the teeth 11 and on the side surface 12 ′ on the slot side of the yoke 12 in the split core 10 shown in FIG. 1.

  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.

  And in this injection molding, the injection resin is also filled into the concave groove 11a of the tooth 11, and this is cured to form a protrusion 21a having a shape and dimension (cross-sectional rigidity) corresponding to the concave groove 11a. .

  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 sectional view taken along the line III-III in FIG. 2 and is an enlarged cross-sectional view of the teeth 11 and the insulator 20 formed therearound.
As is apparent from the figure, the protrusion 21a of the insulator 20 is formed in the concave groove 11a formed in the tooth 11, so that the total length L1 of the insulator 20 is a corner portion composed of a top surface and a side surface. G is divided into a section length L2 of the adjacent ridge 21a and a section length L2 of the adjacent ridges 21a and 21a (in the illustrated example, the total length L1 is divided into four section lengths L2. )

  In addition to the vicinity of the corner portion G, the vicinity of the protrusion 21a has higher rigidity than the other regions of the insulator 20 due to the cross-sectional rigidity of the protrusion 21a. Therefore, even when the insulator 20 undergoes thermal expansion or thermal contraction that is larger than that of the split core 10 under the cooling / heating cycle, the deformation occurs within the high rigidity section length: L2. This leads to the fact that the amount of thermal deformation generated in the insulator 20 is divided according to the number of sections, and accordingly, concentration of temperature stress on the corner portion G is suppressed. That is, the amount of thermal deformation of the insulator 20 is defined by its linear expansion coefficient and the total length of linear expansion, but since this total length is divided into four sections by the highly rigid protrusion 21a (because it is dispersed), Only relatively small thermal deformation occurs in each divided section. Therefore, excessive temperature stress is not generated in the corner portion G as in the case of the conventional structure, and the crack c as shown in FIG. 5 near the corner portion G is effectively eliminated. is there.

FIG. 4 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.

  In the illustrated IPM motor, since the insulator 20 is integrally formed around the teeth 11 of the stator core, an air gap does not occur between the two, and thus has high heat dissipation performance.

  In addition, since the protrusions 21a described above are formed on the insulator 20, it is avoided that excessive temperature stress is generated in the corner portion G of the insulator 20, and thermal stress is dispersed as a result. The occurrence of cracks due to this is effectively suppressed, resulting in a highly durable motor.

  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.

DESCRIPTION OF SYMBOLS 1 ... Electromagnetic steel sheet, 10 ... Split core, 11 ... Teeth, 11 '... Side surface facing teeth slot, 11 "... Top surface not facing teeth slot, 11a ... Groove, 20 ... Resin integral molding insulator, 21 Side surface facing the slot of the insulator, 21a ... Projection, 22 ... Top surface not facing the slot of the insulator, 23 ... Side surface facing the slot of the insulator, 100 ... Stator, 200 ... Rotor, 300 ... Permanent magnet, G ... Corner

Claims (3)

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 teeth and the top surface not facing the slot, an integrally molded insulator is provided,
A stator in which a groove extending in the radial direction is formed on a side surface facing the slot of the tooth, and a protrusion of the insulator is formed in the groove.   The stator according to claim 1, wherein a rectangular wire including 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.   A motor comprising the stator according to claim 2 and a rotor rotating inside the stator.

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