JP2005151684A - Stator for rotary electric machine and sealed-type compressor using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stator for a rotary electric machine capable of suppressing the occurrence of cracks and layer exfoliation during formation and insertion or the like of an insulating film or buckling during automatic insertion in slot insulation of the stator for a rotary electric machine. <P>SOLUTION: The stator for a rotary electric machine is composed of a stator iron core having a plurality of slots and a field coil wound around the iron core via a slot insulating film. The slot insulating film having the following characteristics is used. The thickness of the insulating film is in the range of 50-400 μm. Rupture elongation at a room temperature is 30-180 %. A tensile elastic modulus is 3.8-5.5 GPa. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a rotating electric machine stator and a hermetic compressor using the same.

  In refrigerant systems used for applications such as air conditioning, refrigeration, and refrigeration, chlorofluorocarbon has been used as a refrigerant. However, replacement with an alternative refrigerant that does not contain chlorine element has been promoted from the viewpoint of global environmental problems of ozone layer destruction. . As an alternative refrigerant, HFC-based alternative chlorofluorocarbons made of carbon, hydrogen, and fluorine are used. Recently, natural refrigerants such as carbon dioxide and ammonia, and hydrocarbon refrigerants such as isobutane and propane have been studied and gradually put into practical use as refrigerants having a lower global warming potential from the viewpoint of global warming.

  In the case of a rotating machine, a plastic film is used as a member for electrical insulation in slot insulation, slot spacers, wedges, etc. of a slot insulating part between an iron core and a field coil, and a film covering insulating part that covers the exterior of the rotating machine. . Conventionally, a polyester film such as polyethylene terephthalate (PET) has been widely used as this film from the viewpoint of insulation performance, mechanical properties, heat resistance, workability, cost, and the like.

  However, with the change of the refrigerant as described above, the demand for the characteristics of the electrical insulating film used in the system has also changed. In addition to stability against refrigerants and refrigerating machine oil, improvement in heat resistance and hydrolysis resistance associated with an increase in operating temperature is also required. Components extracted by the refrigerant, such as oligomers, also contribute to clogging of the capillaries.

  Since polyethylene terephthalate film, which has been widely used in the past, has high heat resistance and a continuous use allowable temperature of 120 ° C, and has high hydrolyzability, it can control moisture in the system. is important. Moreover, since the production | generation of an oligomer is seen, it is necessary to use it, fully examining the influence.

  Therefore, as films having higher heat resistance than polyethylene terephthalate, Patent Document 1 (Japanese Patent Publication No. 53-35280), Patent Document 2 (Japanese Patent Publication No. 54-1920), and Patent Document 3 (Japanese Patent Laid-Open No. 48-43198). Publication), Patent Document 4 (Japanese Patent Laid-Open No. 62-115609), and the like have proposed biaxially stretched polyethylene naphthalate films. Polyethylene naphthalate has a glass transition temperature (Tg) higher than that of polyethylene terephthalate, and the allowable continuous use temperature is 155 ° C. It is actually used in systems that require higher heat resistance than polyethylene terephthalate film. However, when polyethylene naphthalate film is applied to a rotating machine, etc., it is likely to cause cracking and delamination when cutting and forming into a slot or wedge and inserting it into a rotating machine, or when forming a coil. Since this may occur, there is room for improvement in terms of productivity.

  As a processing method of polyethylene naphthalate film, it is possible to crack at the time of processing by adjusting the temperature during processing to 25 to 80 ° C., adjusting the radius of curvature of the punch tip at the time of wedge molding or the clearance between the punch wall surface and the die. And a method for preventing delamination. However, in this case, a heating device is required, which leads to an increase in device cost and processing cost. In addition, since the punch curvature radius and clearance are limited, the film size itself and accuracy are limited, and it is not possible to sufficiently meet various demands for rotating electrical machine stators that are miniaturized and refined.

Patent Document 5 (Japanese Patent Laid-Open No. 59-4002) is a laminate of a polyester sheet and an ethylene tetrafluoride sheet. Patent Document 6 (Japanese Patent Laid-Open No. 59-4003) is a polyester sheet and polypropylene. A laminated sheet, Patent Document 7 (Japanese Patent Laid-Open No. 59-63944) is a polyester sheet coated and baked with an aramid resin, Patent Document 8 (Japanese Patent Laid-Open No. 5-115142) is a polyester film and There have been proposed a laminate of aromatic polyamide paper and a laminate of polyethylene terephthalate film and polyethylene naphthalate film. These have the characteristics of each film, but all have advantages and disadvantages in terms of heat resistance and cost.
Japanese Patent Publication No.53-35280 Japanese Patent Publication No.54-1920 JP-A 48-43198 JP-A-62-115609 JP 594002 A Japanese Unexamined Patent Publication No. 59-4003 JP 59-63944 A JP-A-5-115142

  The slot insulation of the rotating electric machine stator as described above has inherent problems such as cracking and delamination during molding and insertion, and waist folding during automatic insertion.

  An object of the present invention is to provide a slot insulating film capable of solving such problems and to apply it to a rotating electric machine stator.

  As a result of diligent studies to solve the above-mentioned problems, special conditions such as heating were applied during cutting, molding, slot insertion, etc. by adjusting the mechanical properties of the slot insulation film, especially the elongation at break and tensile elastic modulus. Rotating electrical machine stators that do not cause cracking or delamination without being placed underneath, and that do not cause hip folding even when automatically inserted by a machine, and can produce a film that does not cause productivity reduction due to good workability It was found that can provide.

  When the slot insulating film has a thickness of 50 to 400 μm, a breaking elongation at room temperature of 30 to 180%, and a tensile elastic modulus of 3.8 to 5.5 GPa, an appropriate waist and hardness are obtained. Therefore, the occurrence of cracks, delamination, and hip breakage during molding and insertion is reduced. Therefore, if the film having the above mechanical properties is used, the workability problem is reduced. Therefore, the film is considered in consideration of other required properties, heat resistance, hydrolyzability, surface slipperiness, electrical properties, cost, etc. The material can be determined. Preferred materials include polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polyether ether ketone, polyether imide, polyimide, polyamide imide, polyether sulfone, aromatic polyamide, and copolymers composed of two or more of these. Is mentioned. Of course, depending on the material, it may be difficult to create a film having the above elongation at break and tensile modulus only by adjusting the film production conditions. In this case, adjust the film by providing a gap in the film. Is preferred. Of course, good effects can be obtained even if these films are used in a laminated manner instead of a single substance.

  The above invention is summarized as follows.

  According to a first aspect of the present application, there is provided a rotating electric machine stator including a stator iron core having a plurality of slots and a field coil wound around the iron core via a slot insulation film. In the range of 50 to 400 μm, the elongation at break at room temperature is 30 to 180%, and the tensile modulus is 3.8 to 5.5 GPa.

  According to a second invention of the present application, in the first invention, the slot insulating film is made of polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polyether ether ketone, polyether imide, polyimide, polyamide imide, poly A rotating electrical machine stator characterized by being a slot insulating film selected from ether sulfone, aromatic polyamide, and a copolymer comprising two or more thereof.

  The third invention according to the present application is characterized in that, in the rotary electric machine stator according to the second invention, the slot insulating film includes a gap in at least a part thereof.

  A fourth invention according to the present application is characterized in that, in the rotating electric machine stator according to the second invention or the third invention, at least two slot insulating films are superposed.

  A fifth invention according to the present application is a hermetic compressor equipped with the rotating electric machine stator of the first invention, the second invention, the third invention, or the fourth invention.

  Further, a sixth invention according to the present application is the above-mentioned fifth invention, wherein at least one refrigerant selected from HFC, HCFC, carbon dioxide, ammonia, isobutane, and propane is used. Type compressor.

  As described above, according to the present invention, there is provided a rotating electric machine stator using an insulating film having a breaking elongation at room temperature of 30 to 180% and a tensile elastic modulus of 3.8 to 5.5 GPa. By doing so, it is possible to suppress the problems inherent to the slot insulation of the rotating electric machine stator, such as molding, cracking or delamination at the time of insertion, or buckling at the time of automatic insertion. Therefore, the defect rate can be reduced and the productivity can be improved, which is industrially effective.

(Embodiment)
Hereinafter, the present invention will be described in more detail.

  The insulating film of the present invention has a film thickness of 50 to 400 μm, a breaking elongation at room temperature of 30 to 180%, and a tensile modulus of 3.8 to 5.5 GPa. When the elongation at break is smaller than this, or when the tensile elastic modulus is large, the film becomes hard and cracks and delamination tend to occur. On the other hand, when the elongation at break is larger than this, or when the tensile elastic modulus is small, the film becomes soft and the rate of occurrence of waist break increases.

  In addition, when the film thickness is reduced, even when the elongation at break and the tensile modulus are within the above ranges, the occurrence of hip folding increases, and depending on the rotating electric machine stator applied, a sufficient insulation distance cannot be obtained, resulting in insulation failure. A case also comes out.

  On the contrary, when the film thickness is increased, the film is easily cracked and the space factor of the coil is relatively decreased, so that the motor efficiency may be decreased.

  When high heat resistance is not required, polyethylene terephthalate is most preferable as described above, but when higher heat resistance is required, polyethylene naphthalate, polyphenylene sulfide, aromatic polyamide and the like are preferable.

  Also, by providing voids in the film, pasting with other films, or coating the film surface, etc., the elongation at break and tensile modulus may be within the above ranges, and other characteristics may be improved. May be.

  In a hermetic compressor having a rotating electric machine stator, when at least one selected from HFC, HCFC, carbon dioxide, ammonia, and isobutane is used as a refrigerant, polyethylene terephthalate may differ depending on operating conditions, temperature, and oil that are different from conventional ones. When the film is difficult to use, it is effective to apply the film adjusted to the required characteristics and the elongation at break and tensile elastic modulus to be in the above ranges.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the examples.

  1. A method for producing an insulating film will be described.

  Although the thickness of the insulating film used by this invention is 50-400 micrometers, More preferably, it is 100-300 micrometers. As described above, when the film thickness is reduced, problems such as insufficient electrical insulation and folding back occur. On the other hand, when the film thickness is increased, there are problems of film cracking, delamination, and a decrease in space factor.

  Moreover, you may add additives, such as an inorganic particle and an organic lubricant, to the insulating film used by this invention as needed. Examples of inorganic particles include silicon oxide, calcium carbonate, alumina, zirconia, titanium oxide, mica, clay, and talc. Examples of the organic lubricant include amide compounds such as stearic acid amide and oleic acid amide. In addition, antioxidants, flame retardants, weathering agents and the like may be added.

  In addition, the insulating film used in the present invention can obtain a good effect even if it is stretched in the uniaxial or biaxial direction or unstretched as long as the elongation at break and the tensile modulus are within the above ranges. .

  An example of a method for producing an insulating film used in the present invention is shown below.

  Chip-like polyethylene naphthalate resin having an intrinsic viscosity of 0.60 dl / g was put into a single screw extruder, melted and kneaded at 300 ° C., and extruded from a die slit. The extruded molten resin was cooled and solidified on a cooling casting drum at 20 ° C. to obtain an unstretched film. Next, the sheet was first stretched in the longitudinal direction at 140 ° C., then stretched in the width direction at 145 ° C., and subjected to heat treatment in a temperature zone controlled at 230 ° C. to prepare a biaxially stretched film. By changing the draw ratio, several types of polyethylene naphthalate films having different elongation at break and tensile modulus were prepared.

  Moreover, the polymethylpentene fine particle was added to the said polyethylene naphthalate resin, it extruded similarly with the single screw extruder, and it extended | stretched and the biaxially stretched film containing the space | gap was also produced. Several types of polyethylene naphthalate films having different elongation at break and tensile modulus were prepared by changing the amount of polymethylpentene added and the draw ratio. Note that a film including voids can reduce the dielectric constant, and thus is an effective film in terms of electrical characteristics.

  In all cases, the film thickness was 250 μm.

  2. The measurement of elongation at break and tensile modulus will be described.

  Measurement of the elongation at break and the tensile modulus of elasticity of the obtained film was in accordance with JIS-K-7127. The film was punched into a JIS No. 4 dumbbell piece, and a tensile test was performed with a tensile tester under conditions of a tensile speed of 50 mm / min and room temperature (25 ° C.).

  3. The processing characteristic evaluation will be described.

  The film was cut to 40 mm in the longitudinal direction and 20 mm in the width direction, and both end portions were folded back by 5 mm in parallel to the width direction to prepare a sample for motor insertion. This sample was automatically inserted into a rotating electric machine stator slot, and an enameled wire was wound. Next, the enameled wire portion was pressed and formed. Evaluation of occurrence of waist break during automatic insertion, cracking during enamel wire partial molding, or delamination.

  In addition, 120 sheets were evaluated for each film.

  4). The evaluation result will be described.

  (Table 1) shows the elongation at break, tensile modulus, number of waist breaks, number of cracks or delaminations in the longitudinal direction of various insulating films.

この結果より、破断伸度が小さく、引張弾性率が大きい場合、割れや層剥離の発生数が多くなる傾向にあり、逆に破断伸度が大きく、引張弾性率が小さい場合には、腰折れの発生が多くなることが判る。

From this result, when the elongation at break is small and the tensile modulus is large, the number of occurrences of cracks and delamination tends to increase, and conversely, when the elongation at break is large and the tensile modulus is small, hip breakage occurs. It turns out that outbreak increases.

  Therefore, it is necessary to use a film having an appropriate range of elongation at break and tensile elastic modulus in order to suppress the occurrence of cracks, delamination, and waist break.

  In the case of using a polyethylene naphthalate film as a slot insulating film, No. of this example. 5-No. 7, no. By using a film having a breaking elongation and a tensile elastic modulus such as 9, it is possible to obtain a rotating electrical machine stator that is less likely to crack or break.

  Therefore, for a hermetic compressor that requires higher heat resistance than polyethylene terephthalate, for example, a compressor having a high discharge temperature that uses carbon dioxide as a refrigerant, the rotating electric machine stator of the present embodiment described above is used. By applying, a hermetic compressor having processability similar to that of conventional polyethylene terephthalate can be provided.

  In this example, polyethylene naphthalate was used, but good effects can be obtained even with the above-described insulating film.

  Further, even if the mechanical characteristics are adjusted by including voids or overlapping two or more films as in this embodiment, a good effect can be obtained.

  The rotating electrical machine stator according to the present invention and the hermetic compressor using the same are inherent problems existing in the slot insulation of the rotating electrical machine stator, such as cracking or delamination at the time of molding, insertion, or automatic insertion. It is effective as a refrigerant system used for applications such as air conditioning, freezing, and refrigeration.

Claims (6)

In a rotating electrical machine stator comprising a stator core having a plurality of slots and a field coil wound around the core via a slot insulating film, the slot insulating film has a thickness of 50 to 400 μm at room temperature. A rotating electrical machine stator having a breaking elongation of 30 to 180% and a tensile elastic modulus of 3.8 to 5.5 GPa. The slot insulating film is made of polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polyether ether ketone, polyether imide, polyimide, polyamide imide, polyether sulfone, aromatic polyamide, and a copolymer comprising two or more thereof. The rotating electrical machine stator according to claim 1, wherein the stator is a slot insulating film. 3. The rotating electrical machine stator according to claim 2, wherein the slot insulating film includes a gap in at least a part thereof. 4. The rotating electrical machine stator according to claim 2, wherein at least two slot insulating films are superposed. A hermetic compressor equipped with the rotating electric machine stator according to any one of claims 1 to 4. 6. The hermetic compressor according to claim 5, wherein at least one refrigerant selected from HFC, HCFC, carbon dioxide, ammonia, isobutane, and propane is used.