JPH10304614A - Rotating electric machine and insulation sheet for electrical apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve heat resistance and ease of machine insertion of a slot insulation by using an insulation sheet formed by affixing a polyethylene naphthalate film on both surfaces of a polyethylene terephthalate film as the slot insulation. SOLUTION: As an insulation sheet used for a slot insulation 10 and an insulating wedge 12, one formed by affixing polyethylene naphthalate films on both surfaces of a polyethylene terephthalate film with an adhesive is used. As a result, the rigidity of the whole insulation sheet can be increased appropriately, and it is possible to improve the ease of machine insertion into a slot 9. The polyethylene naphthalate film itself has characteristic of heat resistance, and the deterioration of an inner layer due to oxidation can be prevented by covering both sides of the polyethylene terephthalate film, thus it is possible to improve the characteristic of heat resistance of the whole insulation sheet 13, and satisfy heat resistance of F-class insulation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotating electric machine and an insulating sheet for electric equipment, and more particularly to a rotating electric machine such as a squirrel-cage induction motor suitable for class F (155.degree. C.) insulation, and to such a rotating electric machine. The present invention relates to an insulating sheet for electric equipment suitable for use.

[0002]

2. Description of the Related Art FIG. 5 shows an example of a rotating electric machine, for example, a general-purpose cage induction motor.

In FIG. 5, reference numeral 1 denotes a housing, which is also called a frame or a frame. The housing 1 is made of a cast iron, a steel plate, or the like and has a substantially cylindrical shape, and constitutes an outer cover of the electric motor.
Reference numerals 2 and 3 denote end brackets, which are also called bearing brackets. The bearings 4 and 5 are housed in the end brackets. Reference numeral 6 denotes a stator, which is a stator core 6a made of a laminate of silicon steel plates.
And a stator winding 6b wound around a number of slots provided on the inner periphery of the stator core 6a. Reference numeral 7 denotes a rotor, and a rotor core 7a made of a laminated body of silicon steel plates, and a cage-type rotor winding (consisting of a conductive bar and an end ring) formed by aluminum die-casting on the rotor core 7a. 7b and a cooling blade 7c, and is attached to the rotating shaft 8. In this figure,
Only the end ring portion of the car rotor winding 7b appears. The rotating shaft 8 is rotatably held by bearings 4 and 5 of the end brackets 2 and 3.
Thus, the rotor 7 is configured to rotate at a position facing the stator 6.

[0004] Further, as shown in FIG.
Is formed by winding a synthetic resin enameled wire 11 in a slot 9 provided on the inner peripheral portion of the stator core 6a through a slot insulator 10 having a substantially U-shaped cross section, for example, by a winding machine. Then, an arc-shaped insulating wedge 12 is driven into the opening of the slot 9 to form the stator winding 6b.
In the slot and insulation treatment for the stator core 6a. Further, an insulating varnish is impregnated into the inside of the slot 9 and the winding end protruding outside the slot 9, and is heat-hardened to be integrally fixed. ing.

[0005] Slot insulator 10 and insulating wedge 12
For example, an aromatic polyamide (Dupont: Nomex: registered trademark) sheet alone or a polyethylene terephthalate sheet alone is used.
For example, an ester imide wire or a polyester amide imide wire is used. As the insulating varnish, for example, a solvent-type insulating varnish containing an organic solvent such as styrene, toluene, or xylene, or a non-solvent-type insulating varnish is used.

On the other hand, JP-A-59-4002 and JP-A-59-4002
JP-A-4003 and JP-A-59-63944 each disclose an F-type insulated electric winding for a general-purpose motor by combining an insulating sheet and a water-soluble insulating varnish.

In JP-A-59-4002, a laminated polyester sheet and an ethylene tetrafluoride sheet are used as an insulating sheet. In JP-A-59-4003, a polyester sheet and a polypropylene sheet are used. A laminated sheet is used, and in JP-A-59-63944, a polyester sheet coated with an aramid resin and baked is used.

[0008]

However, since all of the prior arts use a water-soluble insulating varnish, it takes a long time to heat and cure the varnish, and there is a possibility that moisture may remain after the heat and curing. This is particularly problematic for hermetic motors in which residual moisture is difficult to escape.

In order to reduce the size and weight of the rotating electric machine,
It is necessary to improve the space factor of the winding in the slot and to reduce the radius of curvature at the end of the winding, but with this, the enamel wires 11 and the slot insulator 10 of the enamel wire 11 are required.
If the sliding is poor, the enamel wire is liable to be damaged by being rubbed by the slot portion at the time of winding, and it is difficult to insert the enamel wire, resulting in poor workability.

Further, when an aromatic polyamide sheet alone is used as the slot insulator 10 and the insulating wedge 12, there is no problem in heat resistance, but the rigidity is relatively low, so that the mechanical insertability into the slot is poor. In addition, there is a problem that the material cost is high, and when a polyethylene terephthalate sheet alone is used, the mechanical insertability into the slot is good, but the heat resistance is limited to B-class insulation.

Accordingly, a first object of the present invention is to provide a rotating electric machine capable of improving the heat resistance and mechanical insertability of a slot insulator.

A second object of the present invention is to provide a rotating electric machine capable of improving heat resistance and mechanical insertability of a slot insulator and reducing damage to a coating of an electric wire constituting a stator winding. It is in.

A third object of the present invention is to provide a rotating electric machine that can improve the heat resistance and mechanical insertability of a slot insulator and the heat resistance and crack resistance of an insulating varnish. .

A fourth object of the present invention is to provide a rotating electric machine which can improve the heat resistance and machine insertability of a slot insulator, improve heat dissipation from a housing, and reduce the size and weight of a machine. Is to provide.

Still another object of the present invention is to provide an insulating sheet which is excellent in heat resistance and rigidity and is used for electric equipment such as a rotary electric machine.

[0016]

In order to solve the problems, the present invention uses an insulating sheet having a polyethylene terephthalate film bonded to both sides of a polyethylene terephthalate film as a slot insulator. Insulators whose overall thickness is between 0.05 and
0.55 mm, and the thickness of the polyethylene terephthalate film is set to be 56 to 85% of the thickness of the entire sheet, and the stator winding is constituted by a self-lubricating enameled wire. It is characterized by that
As the insulating varnish, using unsaturated polyester resin or unsaturated epoxy ester resin, more preferably, the cured product of the insulating varnish, a glass transition temperature of 120 ° C. or less, the linear expansion coefficient of 7.0 × 10 ~ ⁵ / C. or lower and an initial elastic modulus at room temperature is 100 to 350 kg / mm ² , furthermore, the housing is made of aluminum alloy die-cast, The sheet was constituted by laminating a polyethylene naphthalate film on both sides of a polyethylene terephthalate film.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will now be described with reference to FIGS.
This will be described with reference to FIGS.

The configuration of a rotating electric machine to which the present invention is applied, for example, a general-purpose squirrel-cage induction motor is almost the same as the configuration of the conventional general-purpose squirrel-cage induction motor shown in FIGS.
They differ in the following points.

That is, in the embodiment shown in FIG. 1, the insulating sheet 1 used for the slot insulator 10 and the insulating wedge 12 is used.
As shown in FIG. 2, a polyethylene terephthalate film 14 is used in which a polyethylene naphthalate film is bonded to both sides of the polyethylene terephthalate film 14 with an adhesive.

The adhesive used here may be a non-solvent type or a solvent type of polyurethane resin, epoxy resin, imide resin and amide imide resin. However, considering the heat resistance of the adhesive and the workability of laminating the adhesive. Curable solvent-based adhesives are preferred. As an example, a polyurethane resin-based adhesive may be used. Generally, a commercially available polyurethane-based adhesive may be used, but isocyanate (preferably aromatic isocyanate) is used in advance from the viewpoint of heat resistance.
A polyurethane-based adhesive comprising an isocyanate prepolymer prepared by reacting a prepolymer with polypropylene glycol, polyester, or the like, and the prepolymer and polypropylene glycol, polyester, polyol, or the like is preferable. The prepolymer and polypropylene glycol, polyester, polyol and the like are uniformly mixed in an organic solvent such as ethyl acetate and butyl acetate to form an adhesive solution. In addition, an inorganic or organic additive such as a flame retardant may be added to the adhesive to such an extent that the adhesiveness is not impaired.

The insulating sheet 13 having such a configuration has good compatibility with an insulating varnish described later, and the characteristics are not deteriorated by heat deterioration. This is because initially, the insulating sheet 13 has good chemical resistance to styrene and the like in the insulating varnish, and
Since the polyethylene naphthalate films 15 on both sides of the polyethylene terephthalate film 14 moderately increase the rigidity of the entire insulating sheet 13, the mechanical insertability into the slot 9 is good, and the polyethylene naphthalate film 15 itself has heat resistance. By covering both sides of the terephthalate film 14, the heat resistance of the entire insulating sheet 13 is improved in order to prevent oxidative deterioration of the inner layer,
A sheet satisfying the heat resistance of class F insulation can be obtained as the insulating sheet 13 as a whole.

As the enamel wire 11, for example, a self-lubricating enamel wire in which a lubricant is applied to the surface or a lubricant is contained in the coating so that the lubricant oozes out on the surface is used. By using such a self-lubricating enameled wire, slippage between the enameled wires 11 and the slot insulating sheet 13 is improved, damage to the coating of the enameled wire 11 is reduced, and winding workability is also improved. Preferably, the self-lubricating enameled wire is excellent in heat resistance, chemical resistance, surface lubrication and abrasion resistance, and is suitable for class F insulation excellent in mechanical insertability into the slot 9.

Further, as an insulating varnish impregnating the inside of the slot 9 and the winding end protruding to the outside of the slot 9, an unsaturated epoxy ester resin or an unsaturated epoxy resin having excellent adhesive strength, crack resistance, chemical resistance and the like is excellent. Polyester resin is used. Among the mechanical forces acting on the stator winding 6b, particularly important stress during operation is considered. Stress caused by heat cycle at start and stop (due to difference in thermal expansion between conductor and insulating layer) and electromagnetic force. Force, and vibrational force due to the rotation of the rotor. The use of an insulating varnish is sufficient for the wear and separation of the insulating layer of the stator winding 6b due to these stresses. can get. The insulating varnish is impregnated into the stator winding 6b or the like, and is cured by heating to obtain a cured insulating varnish having a glass transition temperature of 120 ° C. or less and a linear expansion coefficient of 7.0 × 10 3.
^{~ 5} / ℃ or less and the initial elastic modulus at room temperature is 10
0 to 350 kg / mm ² is selected to further reduce the thermal stress generated during the heat cycle of the stator winding 6b treated with the insulating varnish, and achieve the heat resistance of the class F insulation. Can be.

Further, the housing 1 is made of cast iron or steel plate or aluminum alloy die-cast as in the prior art. When the housing is made of an aluminum alloy die-cast, the heat dissipation (thermal conductivity) is better than when a housing made of cast iron or a steel plate is used. Insulation can be used, and downsizing can be achieved. In addition, if it is made of die-casting, thin and thick parts as designed can be formed with high precision, so there is no need for much machining or the like, and the manufacturing process can be shortened. Since the specific gravity is smaller than that of cast iron or the like, the weight can be reduced.

Further, the insulating sheet 13 shown in FIG.
It can be used not only for the slot insulator 10 and the insulating wedge 12 but also for the insulation of other electric devices. When widely used for electric devices, the polyethylene naphthalate film 15 on both sides of the polyethylene terephthalate film 14 can be used. Moderately increase the rigidity of the entire insulation sheet,
In addition, the polyethylene naphthalate film 15 itself has heat resistance, and covers both surfaces of the polyethylene terephthalate film 14 to prevent oxidative deterioration of the inner layer and increase the heat resistance of the entire insulating sheet. Excellent heat resistance.

Example 1 A heat insulating polyethylene terephthalate film 14 having a thickness of 125 μm and an insulating sheet 13 having a polyethylene naphthalate film 15 having a thickness of 50 μm bonded to both sides thereof were formed into a substantially U-shape.
0 is provided in the slot 9 of the stator core 6a.

A winding 6 b made of a self-lubricating amide imide overcoat ester imide wire (manufactured by Hitachi Cable: 1AI-EIW-E: trade name) 11 is inserted inside the slot insulator 10. Is inserted into the slot 9 and the ends of the windings with an unsaturated epoxy ester varnish (Nitto Denko: NV-5502: trade name). By heating and curing at ~ 160 ° C, the stator 6 was integrally fixed to the stator core 6a to produce the stator 6. Further, the rotor 7 is manufactured by integrally forming the cage-shaped rotor winding 7b and the cooling blade 7c on the rotor core 7a by an aluminum die casting method.

Next, the stator 6 is inserted into the heat-expanded cast housing having an outer diameter of 250 mm, and the rotor 7 is assembled using the end brackets 2 and 3 and the bearings 4 and 5 to build a 3.7 kW motor. Completed a 4-pole squirrel-cage induction motor.

The insulating sheet 13 (50 μm on both sides of a 125 μm-thick polyethylene terephthalate film 14)
(A configuration in which a polyethylene naphthalate film 12 of μm was laminated) was subjected to an insulating varnish treatment under the same conditions as those of the squirrel-cage induction motor, thereby producing a test piece for a tensile test.

As a typical example of the thermal deterioration characteristic of the tensile strength of the insulating sheet 13, the characteristic at 210 ° C. is shown as a characteristic A in FIG. 3, and it becomes 50% of the initial tensile strength at each thermal deterioration temperature of 165 to 210 ° C. FIG. 4 shows an Arrhenius plot as the characteristic A in the case where the life is the time until.

As shown by the characteristic A in FIG. 3, the reduction in strength is remarkably improved as compared with Comparative Example 1 described later, and the heat resistance temperature corresponding to 20,000 hours in FIG. It was confirmed to have.

Note that the tensile test of the insulating sheet 13 was performed with a width 1
A test piece of 5 mm x 200 mm in length was supplied to Shimadzu DSS-
Using a 5000 type autograph, the distance between chucks is 100
mm and a pulling speed of 200 mm / min. In the thermal deterioration test, the test pieces were suspended in hot-air circulating thermostats at temperatures of 210 ° C., 180 ° C., and 165 ° C., taken out after a predetermined time, and subjected to a tensile test. The tensile test was performed at 25 ° C.
And the average value of the five test specimens.

[Example 2] An insulating film prepared in the same manner as in Example 1 except that an insulating sheet 13 in which a 25 µm polyethylene naphthalate film 15 was bonded to both surfaces of a 188 µm thick heat-resistant polyethylene terephthalate film 14 was used. A characteristic at 210 ° C. is shown as a characteristic B in FIG. 3 as a typical example of the thermal deterioration characteristic of the tensile strength of the sheet. Also,
The characteristic A in FIG. 4 shows an Arrhenius plot when the life until the initial tensile strength at each thermal deterioration temperature of 165 to 210 ° C. becomes 50% is taken as the life.

As can be seen from the characteristic B in FIG. 3, the decrease in strength is significantly improved as compared with Comparative Example 1 described later, and the heat-resistant temperature corresponding to 20,000 hours in FIG. It was confirmed that it had heat resistance.

Example 3 An insulating film produced in the same manner as in Example 1 except that an insulating sheet 13 in which a 16 μm polyethylene naphthalate film 15 was bonded to both surfaces of a 188 μm thick heat-resistant polyethylene terephthalate film 14 was used. The characteristic at 210 ° C. is shown as a characteristic C in FIG. 3 as a typical example of the thermal deterioration characteristic of the tensile strength of the sheet. Also,
The characteristic A in FIG. 4 shows an Arrhenius plot when the time until the initial tensile strength at each thermal deterioration temperature of 165 to 210 ° C. becomes 50% is taken as the life.

As can be seen from the characteristic C in FIG. 3, the strength greatly decreases, and the heat resistant temperature corresponding to 20,000 hours in FIG.
° C, and it was confirmed that it had sufficient heat resistance of class F insulation.

[Comparative Example 1] An insulating film produced in the same manner as in Example 1 except that an insulating sheet 13 in which a 9 µm polyethylene naphthalate film 15 was bonded to both surfaces of a heat-resistant polyethylene terephthalate film 14 having a thickness of 188 µm was used. The characteristic at 210 ° C. as a typical example of the thermal deterioration characteristic of the tensile strength of the varnish-treated insulating sheet is shown as characteristic D in FIG. The characteristic A in FIG. 4 shows an Arrhenius plot in which the time until the initial tensile strength at each thermal deterioration temperature of 165 to 210 ° C. reaches 50% is defined as the life.

As can be seen from the characteristic D in FIG. 3, the decrease in the tensile strength was large, and the heat resistance temperature corresponding to 20,000 hours in FIG. 4 was 136 ° C., and it was confirmed that it did not have the heat resistance of class F insulation. .

Example 4 An insulating film produced in the same manner as in Example 1 except that an insulating sheet 13 in which a 75 μm polyethylene naphthalate film 15 was bonded to both surfaces of a heat-resistant polyethylene terephthalate film 14 having a thickness of 75 μm was used. A characteristic at 210 ° C. is shown as a characteristic E in FIG. 3 as a typical example of the thermal deterioration characteristic of the tensile strength of the sheet. Also, 1
The characteristic E in FIG. 4 shows an Arrhenius plot in which the life until the initial tensile strength reaches 50% of the initial tensile strength at each heat deterioration temperature of 65 to 210 ° C. is taken as the life.

As can be seen from the characteristic E in FIG. 3, the decrease in strength is significantly improved as compared with Comparative Example 1 described later, and the heat resistance temperature corresponding to 20,000 hours in FIG. It was confirmed that it had heat resistance.

Embodiment 5 An insulating polyester varnish impregnated into the slot 9 of the stator core 6a and the winding end portion of FIG. 1 and heated and cured is an unsaturated polyester varnish (manufactured by Hitachi Chemical Co., Ltd.).
WP-435H: trade name), and the thermal deterioration characteristics of the tensile strength of the insulating sheet produced in the same manner as in Example 1 were measured.

The tensile strength of this example was less than that of Comparative Example 1 at each deterioration temperature, and the time until the tensile strength at each heat deterioration temperature reached 50% of the initial value was defined as the life, and the tensile strength was determined by an Arrhenius plot. The heat resistance temperature of 20,000 hours is 1
60 ° C.

Example 6 In order to measure the crack resistance of a stator winding conductor treated with an insulating varnish due to thermal stress generated during a heat cycle, a self-lubricating amideimide overcoat esterimide wire (Hitachi Cable) Made: 1AI
-EIW-E: trade name), a bifilar coil was produced, and an unsaturated epoxy ester varnish (Nitto Denko: NV-5502: trade name) was impregnated with the coil, and 150 ° C.
For 2 hours.

Five cycles of a heat cycle test were performed using the bifarer coil as one cycle of 155 ° C./2 hours ℃ −40 ° C./2 hours. As a result, no crack was observed in any of the bifilar coils.

Separately, under the same curing conditions, NV-5
502 produced a resin plate. The resin plate is machined,
A test piece A of 8 mm square and 15 mm thick, and 4 mm wide x 1 thick
A test piece B of mm × 35 mm length was prepared. The glass transition temperature (Tg) and the coefficient of linear expansion (α) of Tg or lower of the test piece A were determined using a TMA-3000 thermophysical tester manufactured by Vacuum Riko.
Further, the tensile elastic modulus at room temperature of the test piece B was determined using a rheological viscoelasticity measuring device DVE-V4.

The Tg of the cured resin of this embodiment is 115 ° C.
α is 6.9 × 10 ^{~ 5} / ℃, tensile modulus at room temperature was 345 kg / mm ^2.

Example 7 An unsaturated polyester varnish (WP-435H, manufactured by Hitachi Chemical Co., Ltd.) was used as an insulating varnish to be immersed and impregnated in a bifilar coil.
A bifilar coil was prepared in the same manner as in Example 6, except that the composition was cured at 3 ° C. for 3 hours.
α and the tensile modulus at room temperature were measured. The results of the heat cycle test were good, with Tg of 66 ° C and α of 5.8.
× 10 ^{~ 5} / ° C, room temperature tensile modulus is 105kg / mm ²
Met.

Comparative Example 2 A bifilar coil was prepared in the same manner as in Example 6 except that an acid anhydride-cured epoxy varnish was used as an insulating varnish to be immersed and impregnated in the bifilar coil and cured at 150 ° C. for 1 hour. The heat cycle test, Tg, α and room temperature tensile modulus were measured.

As a result, in the heat cycle test, cracks occurred in two of the five bifilar coils at the fifth cycle. The Tg of the resin cured product of this comparative example was 1
At 25 ° C., α was 7.2 × 10 ⁵ / ° C., and the tensile modulus at room temperature was 370 kg / mm ² .

Comparative Example 3 The same procedure as in Example 1 was carried out except that a polyethylene terephthalate film alone was used as an insulating sheet constituting a slot insulator, and an esterimide wire was used as an enamel wire constituting a stator winding. A 3.7 kw 4-pole cage induction motor having a stator holding housing made of cast iron having an outer diameter of 223 mm was manufactured, and its weight and volume were measured. This was compared with Example 8 described later.

[Embodiment 8] A 3.7 kw 4-pole cage induction motor was manufactured in the same manner as in Embodiment 1 except that the housing for holding the stator was made of an aluminum alloy die-cast having an outer diameter of 223 mm. The volume was measured and compared with Comparative Example 3.

Assuming that the weight and volume of the comparative example 3 are 100, both the weight and the volume of this example were 70 and 89, respectively.

The aluminum alloy, which is the material of the housing, has higher thermal conductivity and lower density than cast iron.
Furthermore, in the aluminum alloy die-casting method, a molten aluminum alloy is injected into a mold at high pressure, so that voids in the product can be eliminated, and a product having sufficient strength even in a thin portion can be obtained. For this reason, aluminum alloy die-cast housings can be designed with high efficiency by eliminating unnecessary parts while maintaining strength by CAE (Computer Aided Engineering), and are smaller and lighter than cast iron housings. I was able to.

For the above reasons, the squirrel-cage induction motor of this embodiment using a housing made of an aluminum alloy die-cast is smaller and lighter than the squirrel-cage induction motor of Comparative Example 3 as described above.

Each of the embodiments is summarized as follows.
3 and 4, the heat resistance of the insulating sheet was improved as compared with Comparative Example 1 as shown in the characteristic diagram of FIG. Example 4
Is an insulation sheet having a large percentage of the thickness of the polyethylene naphthalate film, so that the heat resistance of the insulation sheet is improved as compared with Comparative Example 1. However, delamination occurs when the slot insulator is inserted into the slot in the machine. And workability was poor.

At a heat resistance temperature equivalent to 20,000 hours in Examples 1 to 4, an improvement of about 17 ° C. or more was observed as compared with Comparative Example 1, and F
The seed insulation was satisfied.

In Examples 1 to 4, the heat resistance can be improved by laminating a polyethylene naphthalate film on both sides of a polyethylene terephthalate film for the following reasons.

The insulating sheets of Examples 1 to 3 each have a polyethylene terephthalate film as a core material, and a polyethylene naphthalate film is bonded to both surfaces thereof. Since there is a polyethylene naphthalate film in the surface layer, only the surface layer of the polyethylene naphthalate film is affected by an organic solvent such as styrene or water contained in the insulating varnish, and the polyethylene terephthalate film of the core material has these effects. Hard to receive. Also, the polyethylene naphthalate film itself has heat resistance,
By covering both sides of the polyethylene terephthalate film, the heat resistance of the entire insulating sheet is improved to prevent the inner layer from being oxidized and degraded, and the insulating sheet as a whole satisfies the heat resistance of class F insulation is obtained. Since the naphthalate film moderately increases the rigidity of the entire insulating sheet, the machine insertability into the slot can be improved. On the other hand, since the thickness of the polyethylene naphthalate film of the surface layer of the insulating sheet of Comparative Example 1 was small, the polyethylene terephthalate film of the core material was not affected by an organic solvent such as styrene or water contained in the insulating varnish. The insulating sheet cannot be sufficiently prevented from being oxidized and deteriorated, and the heat resistance of the entire insulating sheet cannot be improved. As described above, in Comparative Examples 1 to 3, the heat resistance of the polyethylene terephthalate film having low heat resistance is reduced to the same level as that of the polyethylene terephthalate film having low heat resistance while having a heat-resistant polyethylene terephthalate film as a constituent unit, and thus there is a practical problem. In Example 3, as shown by the characteristic E in the characteristic diagram of FIG. 4, the tensile strength of the insulating sheet was excellent without being relatively reduced by thermal degradation at 200 ° C., but the mechanical insertability of the slot insulator into the slot was excellent. Was bad. This is because the elastic modulus of the polyethylene naphthalate film is about 30% higher than that of the polyethylene terephthalate film, and it is weak against impact shear. Also, since the insulating sheet of Example 4 has a relatively high polyethylene naphthalate film ratio as compared with Examples 1 to 3, delaminating is performed by the impact shear force when the slot insulator is inserted into the slot.
Probably a chillon has occurred.

Regarding the thermal stress generated at the winding end portion and the like, as is apparent from the results of the heat cycle tests of Examples 6 and 7, the impregnated insulating varnish has a Tg of cured product.
There 120 ° C. or less, the linear expansion coefficient α at 7.0 × 10 ^{~ 5} / ℃ less, a tensile modulus of 100~350kg / mm ² at room temperature
By using such an insulating varnish, thermal stress can be reduced.

The mechanical insertability of the stator core into the slot was also equal to or greater than that of the case using the polyethylene terephthalate film alone for all the slot insulators using the insulating sheet of this embodiment.

Further, according to the eighth embodiment, a squirrel-cage induction motor in which a housing made of an aluminum alloy die-casting and the class F insulating material of the present embodiment is combined, a cast housing and a F-type housing of the present embodiment are combined.
Cage-shaped induction motors combined with various insulating materials
Comparing the capacity and weight, the cage induction motor using the aluminum alloy die-cast housing has a volume ratio of about 10% and a weight ratio of about 30% as compared with the cage induction motor using the cast housing. % Can be reduced.

[0062]

According to the present invention, an insulating sheet comprising a polyethylene terephthalate film laminated on both sides of a polyethylene terephthalate film is used as the slot insulator, so that the heat resistance of the slot insulator is improved and the polyethylene terephthalate is improved. It is possible to obtain almost the same mechanical insertability into the slot as when using a single film.

Further, since the stator winding is made of a self-lubricating enameled wire, slippage between the enameled wires and the slot insulator is improved, damage to the enameled wire coating is reduced, and winding workability is improved. Can be improved.

Furthermore, since an unsaturated polyester resin or an unsaturated epoxy ester resin is used as the insulating varnish, it has good compatibility with the above-mentioned slot insulator and enameled wire, and can improve the heat resistance and crack resistance thereof. it can.

Furthermore, since the housing is made of an aluminum alloy die-cast, the heat dissipation is good and the insulation can be made compact, so that the rotating electric machine can be miniaturized and each part of the housing can be formed accurately. Therefore, the manufacturing process can be shortened without requiring much machining or the like, and the rotating electric machine can be reduced in weight as compared with a cast iron or the like.

Further, the insulating sheet for electric equipment, which is constituted by laminating a polyethylene naphthalate film on both sides of a polyethylene terephthalate film, is characterized in that the polyethylene naphthalate film of the surface layer is an organic solvent such as styrene or water contained in the insulating varnish. And the like, and the polyethylene terephthalate film as the core material is less susceptible to these effects. In addition, the polyethylene naphthalate film itself of the surface layer has heat resistance, and by covering both sides of the polyethylene terephthalate film, the heat resistance of the entire insulating sheet is improved to prevent oxidation deterioration of the inner layer. A product satisfying the heat resistance was obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a stator inner circumferential slot portion of a cage induction motor.

FIG. 2 is a cross-sectional view showing an insulating sheet used in the present invention.

FIG. 3 is a graph showing thermal degradation characteristics of tensile strength of an insulating sheet.

FIG. 4 is a characteristic diagram obtained by Arrhenius plotting the life characteristics of the insulating sheet at each deterioration temperature.

FIG. 5 is a front view of the squirrel-cage induction motor, which is cut along the upper half thereof.

[Explanation of symbols]

1 ... flange, 6a ... stator core, 6b ... stator winding,
9: slot, 10: slot insulator, 11: enameled wire, 12: insulating wedge, 13: insulating sheet, 14: polyethylene terephthalate film, 15: polyethylene naphthalate film.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shoji Senoo 7-1-1, Higashi Narashino, Narashino-shi, Chiba Industrial Equipment Division, Hitachi, Ltd. (72) Inventor Keisuke Yamanaka 7-1-1, Higashi-Narashino, Narashino-shi, Chiba No. Hitachi Keiyo Engineering Co., Ltd.

Claims (7)

[Claims] 1. A stator, comprising: a housing to which the stator is fixed; and a rotor rotatably held by the housing via bearings, wherein the stator has an iron core having a plurality of slots. In a rotating electric machine comprising a winding housed in a slot of the iron core via a slot insulator, and impregnating the slot insulator and the winding with an insulating varnish and heat-curing, polyethylene as the slot insulator A rotating electric machine using an insulating sheet in which a polyethylene naphthalate film is attached to both sides of a terephthalate film. 2. The insulating sheet according to claim 1, wherein the insulating sheet has a total thickness of 0.05 to 0.50 mm, and the polyethylene terephthalate film has a thickness of 56 to 0.5 times the total thickness of the insulating sheet. A rotating electric machine that is 85%. 3. The stator according to claim 1, wherein the winding of the stator is
A rotating electric machine composed of self-lubricating enameled wire. 4. The rotating electric machine according to claim 1, wherein said insulating varnish is an unsaturated polyester resin or an unsaturated epoxy ester resin. 5. The cured product of claim 4, wherein the cured product of the insulating varnish has a glass transition temperature of 120 ° C. or less, a coefficient of linear expansion of 7.0 × 10 ⁵ / ° C. or less, and an initial elastic modulus at room temperature. Is 100 to 350 kg / mm ² . 6. A rotating electric machine according to claim 1, wherein said housing is made of an aluminum alloy die-cast. 7. An insulating sheet for electric equipment comprising a polyethylene terephthalate film and a polyethylene naphthalate film bonded to both sides.