JP2002176754A - Insulation coating method for rotor and insulation coating thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the natural frequency of a conductor bar from decreasing under a high-temperature environment by applying highly heat-resistant varnish to a clearance between a slot groove and the conductor bar, and miniaturize a rotor. SOLUTION: With the highly heat-resistant liquid varnish 11 fully charged into the slot groove 2, the conductor bar 3 is pressed into the slot groove 2, the conductor bar 3 presses the liquid varnish 11, and the liquid varnish 11 is forcibly pressed into the slot groove 2 and a recessed section formed in the conductor bar 3, so that a varnish layer 11A is formed which is uniform with few air-gaps and has high mechanical strength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulating coating for a rotor and a method for filling a varnish between a plurality of slots of a rotor core and a conductor bar.

[0002]

2. Description of the Related Art FIGS. 3 and 4 are sectional views of a rotor core 1 of a squirrel-cage induction motor comprising a rotor core and a conductor bar, and FIG. 5 is an assembly configuration diagram using the iron core. This is an example. In the drawing, 1 is a rotor core, 2 is a slot groove provided at equal intervals on the circumference of the rotor core 1, 3 is a conductor bar inserted into the slot groove 2 of the rotor core 1, and 4 is a conductor bar. Is a short-circuit ring in which is short-circuited.

[0003] The rotor core 1 is formed by laminating electromagnetic steel sheets formed by punching into a disk shape. Rotor core 1
Has a slot groove 2 for inserting a conductor bar 3,
This slot groove 2 is formed simultaneously with the punching process. The cage type conductor is formed by driving the conductor bar 3 into the slot groove 2 and short-circuiting both ends of the plurality of conductor bars 3 with the short-circuit ring 4.

In order to insert the conductor bar 3 into the rotor core 1, the width of the slot groove 2 must be larger than the width of the conductor bar 3. Therefore, a minute gap 5 is generated between the slot groove 2 and the conductor bar 3. However, in the state where the gap 5 is present, the conductor bar 3 is not sufficiently restrained by the rotor core 1, so that the natural frequency is low, and the conductor portion that resonates may be damaged by fatigue. Therefore, conventionally, the gap 5 is filled with varnish, and the restrained state of the conductor bar 3 is made closer to an ideal fixed end.

Japanese Patent Application Laid-Open No. 58-157355 discloses that a thin insulating layer is formed inside a slot groove by injecting a varnish into the slot groove in advance and then removing the varnish. I have. For example, in the case of aluminum die-casting, a thin insulating layer is formed by injecting a varnish into a slot groove and removing the varnish, and then casting the aluminum.

[0006]

(1) A method of controlling the number of revolutions of an induction motor by controlling the power supply frequency by an inverter and controlling the output of the motor has become general.
Induction motors are becoming faster and smaller. But,
The resonance frequency is complicated by the inverter of the power supply and the rotation speed of the induction motor, and a design for increasing the natural frequency of the rotor is required. (2) Further, the downsizing of the electric motor causes an increase in the maximum temperature of the rotor. In general, varnish is affected by heat, for example, elastic modulus, mechanical strength decreases with increasing temperature,
Exposure to a prolonged high temperature environment causes the varnish to thermally decompose and reduce its volume. It is known that these effects increase with increasing temperature. (3) A decrease in the elastic modulus of the varnish directly contributes to a decrease in the natural frequency of the conductor bar, and a decrease in the mechanical strength and a decrease in the volume of the varnish decrease the natural frequency of the conductor bar through an increase in the gap 5. Contribute. (4) In the method of immersing the rotor in the varnish, it is impossible to fill the varnish with high density (80%) while keeping the viscosity high. Therefore, by increasing the temperature of the varnish, the viscosity of the varnish is reduced. Before immersing the rotor.
This is applicable only to varnishes having a minimum viscosity of not more than the impregnable viscosity (for example, 0.1 Pa.s in the case of epoxy resin), and not applicable to varnishes having high viscosity. It suggests. (5) In a method of inserting a conductor bar after forming an insulating layer by injecting a varnish into a slot in advance and then curing the varnish as in an aluminum die-cast rotor, the conductor bar is inserted without a gap. In order to insert the conductor bar, the conductor bar must be inserted while shaving off the insulating layer fixed to the inner edge of the slot. As a result, the operation time of the conductor bar insertion step increases, and problems such as bending of the conductor bar and bending of the rotor during insertion occur.

An object of the present invention is to provide a method of insulatingly coating a rotor, which can uniformly fill a high heat-resistant varnish between a conductor bar and a slot groove.

[0008]

In order to achieve the above object, a rotor press-fits a conductor bar into a slot groove in a state where a liquid varnish is filled in the slot groove, and heats and cures the liquid varnish. It is to form a gap varnish layer between the slot groove and the conductor bar.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. FIG. 1 shows an example of a method for filling a varnish of a rotor according to the present invention. The rotor core 1 has a slot groove 2, a wind hole 1A and a shaft hole 1B. Wind hole 1
A, the temporary shaft 8 is inserted into the shaft hole 1B, the lower part of the air hole 1A and the shaft hole 1B is closed by the head 8A of the temporary shaft 8, and the jig 9 is attached to the end of the upper temporary shaft 8.
To close the upper air hole 1A and the shaft hole 1B. The rotor core 1 is inserted into a container 6 for filling. A protective sheet 7 is provided on the bottom surface of the filling container 6 facing the slot groove 2. The rotor core 1 is pressed from above by the press 10 through the jig 9 so that the conductor bar 3 is not shaken when the rotor core 1 is driven into the rotor core 1.

In the state shown in FIG. 1, a liquid varnish 11 is poured into a container 6 for filling. The above-mentioned temporary shaft 8 and jig 9 are for preventing the liquid varnish 11 from entering the air hole 1A and the shaft hole 1B. In this state, the slot groove 2 is filled with a sufficient liquid varnish 11.

Next, the conductor bar 3 inserted into the slot groove 2
And the conductor bar 3 is pressed into the slot groove 2 by a hammer from the upper end side. At the time of press-fitting, the lower end of the conductor bar 3 is driven into the protective sheet 7 with a hammer. Protective sheet 7
Functions to prevent the lower end of the conductor bar 3 and the container 6 from being damaged.

When the press-fitting of the conductor bar 3 into all the slot grooves 2 is completed, the load of the press 10 is released, the jig 9 is removed, and the rotor core 1 and the temporary shaft 8 are taken out of the container 6 using a crane or the like. After taking out, temporary shaft 8
The rotor core 1 with the conductor bar 3 is inserted into a heating furnace, the liquid varnish is heated and hardened, and a varnish layer 12A is formed in the gap 5 between the slot groove 2 and the conductor bar 3 shown in FIG.
To form Then, the conductor bar 3 is cleaned, and the conductor bar 3
The rotor is manufactured by attaching the short-circuit ring 4 between them and performing machining.

In this manufacturing method, while the slot groove 2 is filled with a sufficient liquid varnish 11, the conductor bar 3 inserted into the slot groove 2 is hammered into the slot groove 2 with a hammer. Press into. As a result, the conductor bar 3 presses the liquid varnish 11, and the liquid varnish 11 is forcibly pressed into the slot groove 2 and the concave portion formed in the conductor bar 3, thereby forming a uniform varnish layer 11A having a small gap. I do. Since the varnish layer 11A can increase the mechanical strength by the amount of pressing, it is difficult to cause dielectric breakdown, and the varnish layer 11A is densely filled in the gap 5, so that the natural frequency of the conductor bar can be increased. it can.

Further, according to the manufacturing method of the present invention, a high-viscosity high-heat-resistant varnish obtained by adding an inorganic filler such as alumina to a solvent-free liquid resin such as an epoxy resin or a silicone resin can be easily injected into the slot groove 2. Can be. For this reason, the heat resistance of the varnish layer 11A is increased, the current capacity of the conductor bar 3 is increased due to the fact that insulation breakdown is less likely to occur, and the rotor and the cage induction motor can be enlarged or reduced accordingly. . Furthermore, since a highly heat-resistant varnish can be used, the natural frequency of the conductor bar does not easily decrease even under a high temperature condition.

In the above embodiment, the container is filled with the liquid varnish. However, the conductor bar may be press-fitted into the slot groove 2 with the liquid varnish directly filled in the slot groove. Further, although the rotor of the cage type induction motor has been described, it is needless to say that the present invention can be applied to the rotor of another rotating electric machine.

[0016]

As described above, according to the present invention, the rotor and the squirrel-cage induction motor can be miniaturized. Further, since a varnish having high heat resistance can be used, it is possible to provide a rotor having a high natural frequency of the conductor bar even under a high temperature condition.

[Brief description of the drawings]

FIG. 1 is a sectional view of a container for explaining a method of manufacturing a rotor shown as an embodiment of the present invention.

FIG. 2 is a partial sectional view of a rotor core manufactured according to FIG. 1;

FIG. 3 is a plan view of a rotor core of a conventional cage-type induction motor.

FIG. 4 is a partial cross-sectional view of a rotor core used in FIG. 3;

FIG. 5 is a sectional view of a rotor of the cage induction motor used in FIGS. 3 and 4;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rotor core, 2 ... Slot groove, 3 ... Conductor bar, 4 ...
Short-circuit ring, 5: gap, 6: container.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H013 LL01 MM04 NN05 5H604 AA05 BB01 BB09 BB14 CC02 CC05 CC15 DB02 PB03 PE06 5H615 AA01 BB01 BB06 PP02 PP08 PP13 QQ12 RR07 SS05 SS10 SS19 SS24 SS44 TT31

Claims (4)

[Claims] 1. A rotor core having a plurality of slot grooves,
In a method of insulating coating a rotor, in which a conductor bar is inserted into these slot grooves and an insulating layer is formed in a gap between the slot groove and the conductor bar, a liquid insulator is filled in the slot groove, and the inside of the slot groove is filled. Pressurizing one end of the conductor bar inserted into the groove, press-fitting the conductor bar into a slot groove, heat-curing the liquid insulator in the gap to form an insulation layer, and forming an insulation layer on the rotor. Method. 2. The method according to claim 1, wherein a high heat-resistant varnish obtained by adding an inorganic filler to a high heat-resistant solventless liquid resin is used as the insulator. 3. An insulation coating for a rotor, wherein a gap between a slot groove of a squirrel-cage induction motor and a conductor bar is filled with a highly heat-resistant insulator. 4. The insulated cover of the rotor according to claim 3, wherein a varnish obtained by adding an inorganic filler to a solventless liquid resin is used as the high heat resistant insulator.