Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2000-01-14
2001-02-20
Mullins, Burton (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S179000, C310S215000
Reexamination Certificate
active
06191508
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
The present application is based on and claims priority from Japanese Patent Applications Hei 11-9043 filed Jan. 18, 1999, and Hei 11-222389 filed Aug. 5, 1999, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a stator insulation structure of a rotary electric machine and, particularly, of a stator winding having connection portions covered by insulation-resin-coating.
2. Description of Related Art
It is known that a stator of a vehicle AC generator has a stator winding formed of a plurality of conductor segments which are welded to one another. For example, JP-A-62-272836 or JP-A-63-274335 discloses such an armature coil. Such an armature coil is formed of conductor segments, which are welded to one another at their ends in a wave-wound type. The coil ends are covered with and supported by resin coating.
Because muddy water may get into the inside of the AC generator when the vehicle is driven on a rough road, it is necessary that insulation resin coating is coated after conductor segments are welded to one another at their ends. However, the above disclosed armature coil only has only support coating that covers conductor members of coil ends. There is no detailed explanation about the insulation performance. Because the support coating needs a certain hardness, gaps may be formed between conductor members and the resin coating. Therefore, muddy water or other electrolyte may get into the inside of the generator to cause an insulation failure. Therefore, it is necessary to tightly cover connection portions.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above problems and has an object to provide an insulation structure of a stator of rotary electric machine, which includes a vehicle AC generator.
In the insulation structure of a rotary electric machine according to the invention, the modulus of elasticity of the insulation resin coating is so small that the insulation resin coating will not peel off from the connection portions. It has been found that the allowable value of the modulus of elasticity changes according to the thickness of said insulation resin coating. A shearing force to peel off the insulation resin coating changes due to the material of the stator winding. The maximum allowable modulus of elasticity changes as thickness of the insulation resin coating changes. Accordingly, insulation resin coating having a modulus of elasticity that is less than the maximum allowable modulus of elasticity can prevent the insulation resin coating from peeling off. The insulated connection portions endure well.
In particular, it is preferable that the thickness of the insulation resin coating is 0.5 mm, and the stator winding is made of copper. In a vehicle AC generator, gaps between connection ends are mostly about 0.5 mm and the stator winding is made of copper. These limitations decide the shearing force of peeling off the insulation resin coating. Thus, the maximum allowable modulus of elasticity is decided according to the thickness of the insulation resin coating. Therefore, the insulation resin can be easily selected from various materials.
If silicone contains a certain amount of oxidant inhibitor, it becomes resistant to thermal shock cycles. Therefore, silicone can be used as the insulation resin coating.
If epoxy resin contains coefficient-of-expansion adjusting material, it can reduce the shearing force. Therefore, epoxy resin can be suitable as the insulation resin coating.
The percentage content of the oxidant inhibitor is preferably between 0.01% and 5.0%. On the other hand, the percentage content of the coefficient-of-expansion adjusting material is preferably between 0.01% and 70%.
The vehicle AC generator's stator according to a preferred embodiment of the invention includes a stator core having a plurality of slots and a stator winding having a plurality of conductor segments which are disposed in the plurality of slots and are connected with one another at ends thereof. The connection portions of the stator winding are covered with the above stated insulation resin coating. The vehicle AC generator is always exposed to muddy water or the like that may cause insulation failure. However, the above stated insulation resin coating covers the connection portions completely and would not peel off, so that the connection portions can be completely prevented from short-circuiting with other parts.
REFERENCES:
patent: 4562164 (1985-12-01), Miyazaki et al.
patent: 5097167 (1992-03-01), Kanayama et al.
patent: 62-272836 (1987-11-01), None
patent: 63-274335 (1988-11-01), None
Aoki Takashi
Kato Mitsuru
Matsubara Shinichi
Sato Kazuhide
Denso Corporation
Mullins Burton
Pillsbury Madison & Sutro LLP
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