JPH0681456B2 - Insulation method for stator of rotating electric machine - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a direct electromagnetic forced external force in order to reduce vibration and noise at the time of resonance between the natural frequency of the stator core of a rotating electric machine and the frequency of electromagnetic force waves. The present invention relates to a method of insulating a stator for a rotary electric machine, which reduces vibration and noise by giving a large vibration damping effect to a stator core that receives the heat.

[Technical Background of the Invention and Problems Thereof] AC motors are widely used because they can easily convert electrical energy into mechanical energy, and in recent years, various machines using AC motors as drive sources perform speed control using an inverter. There are many things going on. However, in the speed control by the inverter, the voltage and current waveforms are distorted, magnetic flux harmonics are generated in the stator and rotor of the AC motor, and the electromagnetic force thereof causes vibration and noise. Furthermore, in a fixed frequency electric motor, resonance with the frequency of the electromagnetic force wave was avoided by avoiding the natural frequency of the stator core, but this is difficult because the frequency is variable in speed control using an inverter. is there. Conventionally, as a means for absorbing such vibration, it has been considered that the stator core of the electric motor is elastically supported on the stator frame by an elastic beam, but an elastic support material that effectively absorbs vibration is obtained. Didn't. In order to elastically support it, it is necessary to interpose an elastic member, so that the rotary electric machine itself has a large volume, and there is a drawback that the cost is considerably increased due to an increase in material cost and manufacturing man-hours.

[Object of the Invention] An object of the present invention is to provide a method for insulating a stator of a rotating electric machine, which can reduce vibration and noise by imparting a large vibration damping characteristic to a stator core that is directly subjected to an electromagnetic external force. To do.

SUMMARY OF THE INVENTION According to the present invention, a winding wound by random winding and accommodated in a slot of a stator core is subjected to varnish impregnation treatment at least twice, and in this case, the first impregnation treatment step has high flexibility and permeability. It is characterized by using a varnish and a varnish having a hardness higher than that of the first one in the second impregnation treatment step, which gives a large vibration damping characteristic to the stator core, and a considerably effective vibration. The noise reduction effect can be expected.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an electric motor 1 to which the present invention is applied. In FIG. 1, 2 is a stator frame that supports a stator core 3, 4 is a rotor, and a rotary shaft 5 of the rotor 4 is supported by a bracket 7 on the stator frame 2 side through a bearing 6. ing. A winding 8 is wound around the stator core 3 by, for example, random winding, and a coil end 8a thereof projects relatively long due to the random winding. This winding 8 is specifically the second
As shown in the figure, the slot 9 is housed in the slot 9 through a U-shaped slot insulator 10, and the slot wedge 11 prevents the escape.

As described above, the winding 8 is subjected to varnish impregnation treatment twice in a state of being wound around the stator core 3. That is,
In the first impregnation process, a rubber-based silicone varnish with high flexibility and permeability is used, with an average of 0.010 mm.
Process to a film thickness of the order. In this case, as the varnish, those having a Shore hardness (however, according to the type A tester, the same hereinafter in this specification) of 50 or less can be used, and in this example, a Shore hardness of 50 was used. After that, in the second impregnation treatment step, for example, an epoxy varnish having a higher hardness than that used in the first impregnation treatment step is used. In this case, as the varnish, one having a Shore hardness of 200 or more can be used, and one having a Shore hardness of 200 was used in this example.

As a result, since the low hardness varnish having high flexibility and permeability is used in the first impregnation treatment step, this varnish is used between the laminated steel sheets of the stator core 3, the slot 9 surface, the slot insulator.
10 and between the three members of the winding 8 and between the wires of the winding 8 are sufficiently penetrated. As a result, a soft insulating layer of varnish is formed on the surface of the winding wire 8 and between the wires of the winding wire 8. Therefore, when an electromagnetic force is directly applied to the side of the stator core 3, friction occurs in the soft insulating layer due to the varnish that has penetrated between all the members as described above due to relative displacement between the members via the soft insulating layer, resulting in a vibration damping effect. Exert. In the second impregnation process, a hard insulating layer made of hard varnish is formed on the surface of the winding 8 (soft insulating layer) and between the winding 8 and the slot 9. As a result, the insulation and heat resistance of the winding wire 8 are improved, the mechanical strength is improved, the winding wire 8 is fixed to the stator core 3, and the surface of the winding wire 8 is protected.

FIG. 3 shows an example of measurement of vibration response characteristics of a single stator, in which the horizontal axis represents frequency λ and the vertical axis represents α / F (F is force, α
Is the vibration acceleration). In FIG. 3, (A)-
(C) is an example in which the varnish impregnation treatment is performed only once. Particularly, (A) shows the case where the hardness of the varnish used is "high", (B) shows "medium", and (C) shows "low" ( However, the shore hardness is 50 or less), and (D) also shows the case where the varnish impregnation treatment is performed twice with different hardness as in the above-mentioned embodiment of the present invention. As is apparent from FIG. 3, it can be seen that the insulation treatment method according to the present invention provides a high vibration damping effect.

In order to achieve this, no special elastic member is required, and the volume of the electric motor 1 does not increase, so that the production cost is low.

In particular, it is useful for reducing vibration and noise of electric motors that use a variable frequency power supply such as an inverter and whose resonance point cannot be avoided.

[Effects of the Invention] According to the present invention, as described above, the varnish impregnation treatment of the stator winding is performed with the varnish having high flexibility and permeability and low hardness at the first time, and with the varnish having high hardness at the second time. As a result, it is possible to provide a method for insulating a stator of a rotary electric machine, which is expected to have a high vibration damping effect.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an electric motor that implements the method of the present invention,
2 is an enlarged vertical sectional view taken along the line II-II of FIG. 1, and FIG. 3 is a vibration response characteristic diagram of the stator. In the figure, 2 is a stator frame, 3 is a stator core, 4 is a rotor, 8
Is a winding.

Claims (1)

[Claims] 1. A method for performing insulation treatment by impregnating varnish on a winding for a rotating electric machine, the winding being formed by random winding and being housed in a slot of a stator iron core. A first impregnation treatment step of forming a soft insulating layer between the surface of the winding and the wires of the winding by impregnating a varnish having a Shore hardness of 50 with high flexibility and permeability. A second step of impregnating the winding with a varnish having a Shore hardness of 200 after the impregnation treatment step to form a hard insulating layer between the surface of the winding and the winding and the slot;
And an impregnation treatment step.