JP5429313B2 - Molded motor - Google Patents

Description

  The present invention relates to a bracket structure for a molded motor.

The bracket of a molded motor mounted on an electric device such as a small air conditioner has a structure in which a bearing holding portion is formed by a pressed product of a steel plate and is fixed to the molded stator side by, for example, press-fitting. Yes. (For example, see Patent Document 1)
FIG. 3 is a structural sectional view of a conventional molded motor. As shown in FIG. 3, the bracket 35 has a bearing holding portion formed by pressing a steel plate. The conventional mold motor 300 has a structure in which a bracket 35 is press-fitted and fixed to a stator final product in which a stator 33 in which a stator winding 32 is wound around a stator core 31 insulated with resin is molded with a mold resin 34. It has become. The rotor 39 is formed integrally with the shaft 30 and is rotatably arranged on the inner peripheral side of the stator 33. The shaft 30 is supported by a bearing A36 and a bearing B37, and the bearing A36 and the bearing B37 are fixed by a bearing holding portion of the bracket 35 and a bearing housing 38, respectively.

JP-A-9-154260

  The structure of the molded motor 300 having the above structure will be described with reference to FIG. As shown in FIG. 3, the bracket 35 of the mold motor 300 is close to the stator winding 32 via the mold resin 34. For this reason, a potential for driving the motor from the stator winding 32 is induced in the bracket 35, and a potential is generated between the bracket 35 and the shaft 30. And the electric current flows in bearing A36 with the electric potential, and an electric corrosion generate | occur | produces.

  As a measure against electric corrosion, it is necessary to use a ceramic bearing or a bearing using conductive grease, but there are problems such as an increase in cost or lack of reliability.

  The molded motor of the present invention is formed integrally with a stator in which a stator stator winding is wound around a stator core, a shaft passing through the center, and the shaft, and is rotatably arranged on the inner peripheral side of the stator A rotor, a bearing that supports the shaft, and a finished bracket that fixes the bearing. The stator is molded with mold resin. The finished bracket product has a bearing housing portion that holds the bearing, and a conductive bracket that opposes the stator winding via the molding resin and press-fits the finished bracket product into the molding resin. The bearing and the bracket are insulated by resin.

  With such a configuration, even if an electric potential is generated between the bracket and the shaft, no electric current flows in the bearing due to the electric potential, and electrolytic corrosion can be prevented.

FIG. 1 is a structural cross-sectional view of a molded motor according to Embodiment 1 of the present invention. FIG. 2 is a structural cross-sectional view of a molded motor according to Embodiment 2 of the present invention. FIG. 3 is a structural sectional view of a conventional molded motor.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the following embodiments.

(Embodiment 1)
Hereinafter, the structure of the finished bracket of the molded motor according to Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is a structural sectional view of a molded motor according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the molded motor 100 includes a stator 13, a shaft 20 penetrating the center, a rotor 19, a bearing A16 and a bearing B17 that support the shaft 20, and a finished bracket that fixes the bearing A16. 15. The bearing B17 is fixed by a bearing housing 18. The stator 13 is configured by winding a stator winding 12 around a stator core 11 insulated with resin. The rotor 19 is formed integrally with the shaft 20 and is rotatably arranged on the inner peripheral side of the stator 13. The stator 13 is molded with a mold resin 14 to form a stator final product.

  The finished bracket 15 is composed of a conductive bracket 15a formed of a steel plate (metal) and a bearing housing portion 15b formed of resin. The bracket finished product 15 is press-fitted and fixed to the stator finished product by press-fitting the bracket 15 a into the mold resin 14. With such a configuration, the bearing A16 and the bracket 15a are insulated by the resin forming the bearing housing portion 15b. The resin material forming the bearing housing portion 15b is preferably an unsaturated polyester resin from the viewpoint of strength.

  The relative dielectric constant of the resin forming the bearing housing portion 15b is preferably 3-5. When the relative dielectric constant of the resin is 3 to 5, insulation can be secured. If the relative dielectric constant of the resin is greater than 5, a resistance component often appears and it is difficult to ensure insulation. With such a configuration, a potential for driving the motor from the stator winding 12 is induced in the bracket 15a, but is insulated by the bearing housing portion 15b. For this reason, even if an electric potential is generated between the bracket 15a and the shaft 20, no electric current flows in the bearing A16 due to the electric potential, and electrolytic corrosion can be prevented.

  Further, the inside of the mold motor 100 has a stray capacitance of several tens pF to several hundred pF, and the bearing A16 also has a stray capacitance of about several pF to 100 pF. For example, the stray capacitance of the bearing A16 is 100 pF, and the stray capacitance of the insulating portion of the bearing housing portion 15b formed of resin is 10 pF. Assuming that the bearing A16 and the insulating portion are in series, assuming that the voltage applied to the bearing A16 when there is no insulating portion is 100, the magnitude of the voltage is about 10 by providing the insulating portion. Thereby, the voltage concerning bearing A16 can further be reduced and electrolytic corrosion can be prevented. Therefore, it is desirable that the stray capacitance of the insulating portion of the bearing housing portion 15b, that is, the electrostatic capacitance between the bearing A16 and the bracket 15a be 10 pF or less. The bearing housing 18 is also formed of resin in the same manner as described above.

(Embodiment 2)
Next, the molded motor in Embodiment 2 of this invention is demonstrated based on FIG. FIG. 2 is a structural cross-sectional view of the molded motor according to Embodiment 2 of the present invention. In addition, the same code | symbol is attached | subjected to the part same as Embodiment 1, and description is abbreviate | omitted.

The bracket finished product 25 of the molded motor 200 in the present embodiment is a steel plate (metal).
The bracket 25a formed from the above, the conductive bearing housing portion 25b formed from steel (metal), and the connection holding portion 25c formed from a resin that holds and connects the bracket 25a and the bearing housing portion 25b. Is provided. The bracket final product 25 is press-fitted and fixed to the stator final product by press-fitting the bracket 25 a into the mold resin 14. With such a configuration, the bearing A16 and the bracket 25a are insulated by the resin forming the connection holding portion 25c.

  Further, the relative dielectric constant of the resin forming the connection holding portion 25c is desirably 3 to 5 for the same reason as in the first embodiment. With such a configuration, a potential for driving the motor from the stator winding 12 is induced in the bracket 25a, but is insulated by the connection holding portion 25c formed of resin. For this reason, even if an electric potential is generated between the bracket 25a and the shaft 20, no electric current flows in the bearing A16 due to the electric potential, and electrolytic corrosion can be prevented. Further, since the bearing housing portion 25b is formed of a steel plate, deformation due to heat can be prevented and the bearing A16 can be fixed more firmly.

  Furthermore, for the same reason as in the first embodiment, it is desirable that the stray capacitance of the insulating portion of the connection holding portion 25c formed of resin, that is, the capacitance between the bearing A16 and the bracket 25a is 10 pF or less. Thereby, the voltage concerning bearing A16 can further be reduced and electrolytic corrosion can be prevented.

  As described above, the molded motor according to the present invention can be applied to applications such as a motor mounted on an electric device such as a small air conditioner.

11 Stator Iron Core 12 Stator Winding 13 Stator 14 Mold Resin 15 Bracket Finished Product 15a Bracket 15b Bearing Housing 16 Bearing A
17 Bearing B
18 Bearing housing 19 Rotor 20 Shaft 25 Finished bracket 25a Bracket 25b Bearing housing 25c Connection holding part

Claims (6)

A stator having a stator core wound with a stator winding;
A shaft passing through the center,
A rotor formed integrally with the shaft and rotatably arranged on the inner peripheral side of the stator; a bearing supporting the shaft;
A bracket finished product for fixing the bearing,
The stator is molded with a mold resin,
The bracket finished product has a bearing housing part that holds the bearing and the stator winding through the mold resin, and has a conductive bracket that press-fits the bracket finished product into the mold resin,
The bracket has a plate-like cross section, and the end of the bracket on the shaft side is orthogonal to the axial direction of the shaft and is opposed to the outer ring of the bearing in the radial direction.
A molded motor in which the bearing and the bracket are insulated by a resin. The molded motor according to claim 1, wherein the bearing housing portion is formed of resin. The finished bracket product further includes a connection holding portion for connecting and holding the bearing housing portion and the bracket, wherein the bearing housing portion is formed of metal, and the connection holding portion is formed of resin. Item 2. The molded motor according to Item 1. The molded motor according to any one of claims 1 to 3, wherein the resin has a relative dielectric constant of 3 to 5. 4. The molded motor according to claim 1, wherein a capacitance between the bearing insulated by the resin and the bracket is 10 p or less. 5. An electric device comprising the molded motor according to claim 1.