JPH10234166A - Rotor for induction motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rotor for induction motor, having low secondary resistance and good characteristics by coupling a bind bar, in which copper and aluminum are bonded through a reactive layer, with an end ring through aluminum diecast to form a secondary conductor, thereby surely bonding copper and aluminum. SOLUTION: End rings 9 are formed at the opposite ends of a squirrel-cage rotor 5, comprising a rotor core 6 fixed with a central shaft 8 and having slots 7 in which bind bars 1 of secondary conductor, are formed. The bind bar 1 is made of a copper 2 in the shape of the slot 7 which is applied with an aluminum coating 3, and a reaction layer 4 to the copper 2 is formed on the inner circumferential surface of the aluminum coating 3. The end ring 9 is formed by an aluminum diecast, while setting the bind bar 1 in the slot 7. According to the structure, the copper 2 and the aluminum coating 3 can be bonded firmly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor for an induction motor, and more particularly to a rotor for an induction motor suitable for improving characteristics.

[0002]

2. Description of the Related Art Induction motors are rugged and maintenance-free, and are therefore widely used, from small ones for home appliances to large ones for industrial use. These induction motors are still desired to be inexpensive and have high performance, and various studies have been made. In the cage rotor of an induction motor, it is common to form a secondary conductor consisting of a bar and an end ring by aluminum die casting in terms of price, but from a performance standpoint, it is desirable to form a secondary conductor by copper and die casting. It is desirable to form a conductor. However, copper and die casting are disclosed in
As described in Japanese Patent Publication No. 16, since the melting temperature of copper is high, changes in production equipment and changes in the characteristics of iron core materials pose problems. On the other hand, Japanese Utility Model Application Laid-Open No. 58-22833,
Although the characteristics are lower than those of the cage rotor provided with the aluminum die-casting described in Japanese Patent No. 978, a combined die-cast using both copper and aluminum has been proposed as described in Japanese Patent Application Laid-Open No. H8-223978.

[0003]

The above prior art has been noted that the combined use of copper and aluminum can reduce the secondary resistance of the secondary conductor. However, although the copper-aluminum bondability is good, No consideration was given to the bonding with aluminum die casting. That is, the inventors have experimentally confirmed that copper and aluminum are not bonded depending on a bonding method such as aluminum die casting.

[0004] A first object of the present invention is to provide a rotor for an induction motor having good characteristics with small secondary resistance by reliably coupling copper and aluminum.

A second object of the present invention is to provide a rotor for an induction motor, which reliably couples copper and aluminum and does not reduce the starting torque.

[0006]

To achieve the first object, a rotor of an induction motor according to the present invention has a cage shape in which a secondary conductor is formed by aluminum die casting on a rotating core having a plurality of slots. In a rotor of an induction motor having a rotor, a bar of the secondary conductor of the cage rotor is
A copper bar is provided in the slot, the outer periphery of the copper is covered with aluminum, and the copper and aluminum are combined via a reaction layer to form a bind bar. The bind bar and the end ring are made of aluminum. The secondary conductor is formed by being connected by die casting.

A bar of the secondary conductor of the cage rotor is a bind bar that is disposed in the slot, covers the outer periphery of copper with aluminum, and connects the copper and aluminum via a reaction layer. And forming a slot area at both axial ends of the rotating core larger than a central slot area, and connecting the bind bar and the end ring by aluminum die casting to form a secondary conductor. It is characterized by having been formed.

In order to achieve the second object, the rotor of the induction motor according to the present invention is characterized in that the aluminum coating on the outer peripheral side of the slot is formed thicker than the inner peripheral side.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a perspective view showing the shape of a bar of a rotor of a squirrel-cage induction motor of the present embodiment, and FIG.
FIG. 3 is a longitudinal sectional view showing an axial section of a rotor of the squirrel-cage induction motor of the present embodiment, and FIG. 3 is a sectional view taken along line AA of FIG.

As shown in FIGS. 1 to 3, the cage rotor 5 of this embodiment has a secondary conductor bind bar 1 in a slot 7 formed in a rotor core 6 to which a central shaft 8 is attached. Are formed at both ends thereof.
Is formed. The bind bar 1 has an aluminum coating 3 on copper 2 formed in the shape of a slot 7.
Has been given. That is, after the oxide film is removed by applying a plast to the surface of the copper 2 previously formed into the shape of the slot 7, aluminum is mechanically bound to the outer peripheral surface of the copper 2, and a temperature of 500 ° C. to 700 ° C. The heat treatment is performed in the range, the aluminum coating 3 is fixed on the outer peripheral surface of the copper 2, and the reaction layer 4 with the copper 2 is formed on the inner peripheral surface of the aluminum coating 3. The end ring 9 is formed by placing the bind bar 1 in the slot 7 and performing aluminum die casting. Since the bind bar 1 and the end ring 9 are formed in this manner, the reaction layer 4 formed on the outer peripheral surface of the copper 2 and the inner peripheral surface of the aluminum coating 3 has a relatively high resistance, and 2, the current flowing through the end ring 9 flows from the end ring 9 to the copper 2 via the aluminum coating 3 and the reaction layer 4 as shown by the arrow 11.
Here, the copper loss of the reaction layer 4 is determined by the reaction layer 4 and the end ring 9.
The copper loss is negligibly small because the reaction layer 4 is thin. The resistance of the end ring 9 is about 10% of the resistance of the bind bar 1. As described above, in the squirrel-cage rotor of this embodiment, the secondary resistance is determined by the portion of copper 2 and can be reduced to about 1 / 2.5 as compared with the case of aluminum. Further, from the viewpoint of reliability, the aluminum of the end ring 9 and the bind bar 1 are firmly bonded, and the aluminum coating 3 of the bind bar 1 and the copper 2 are firmly bonded by the reaction layer 4. Even if a centrifugal force acts on the end ring 9 during operation of the induction motor, mechanical strength can be maintained. In addition, since it is formed as described above, the variation is small, and a better assurance of the actual machine can be obtained.

Another embodiment of the present invention will be described with reference to FIGS. 4 is a longitudinal sectional view showing a radial section of the rotor of the squirrel-cage induction motor of the present embodiment, FIG. 5 is a sectional view taken along line AA of FIG. 4, and FIG. 6 is a sectional view taken along line B of FIG. It is -B sectional drawing.

As shown in FIGS. 4 to 6, the squirrel-cage rotor of the present embodiment is constructed in the same manner as the embodiment shown in FIGS. 1 to 3, but in this embodiment, the size of the slot 7 is reduced. Are formed differently at both ends and the center side of the rotor core 6. That is, a slot 71 having a small slot area is provided in the rotor core 61 on the center side and the rotor core 62 on both ends.
Is formed with a slot 71 having a larger slot area than the slot 71. When formed in such a shape, the bind bar 1 is set in the slots 71 and 72 and subjected to aluminum die casting to form the end ring 9.
When the end ring 1 is formed, a part of the end ring 91 enters the slot 72 of the rotor core 62, so that the end ring 1
2 are formed. Thereby, even if a centrifugal force acts on the end ring, the mechanical strength can be improved.

Another embodiment of the present invention will be described with reference to FIG. FIG. 7 is a longitudinal sectional view showing a radial section of the rotor of the squirrel-cage induction motor of the present embodiment.

The squirrel-cage rotor of the present embodiment is also constructed in the same manner as the embodiment shown in FIGS. 1 to 3, but in this embodiment,
The cross-sectional area of the copper 21 is smaller than that of the copper 2 shown in FIG. For this reason, the thickness of the aluminum coating 31 on the outer peripheral side of the rotor of the slot 7 increases. In general, when the secondary conductor is formed of copper, the secondary resistance decreases and the starting torque decreases,
In this embodiment, since the aluminum layer can be formed thick on the outer peripheral side of the slot 7, the secondary resistance can be reduced without lowering the starting torque, and an induction motor with good characteristics can be obtained.

[0015]

As described above, according to the present invention,
Since the copper bar is coated with aluminum and heat-treated to form a reaction layer between copper and aluminum to form the bind bar, the copper and aluminum coating can be firmly bonded. Also, since the above-described bind bar is arranged in the slot and subjected to aluminum die casting to form an end ring, the secondary resistance can be made smaller than aluminum, and an induction motor with good characteristics can be provided. It can be firmly connected to the end ring. Thereby, even if centrifugal force acts by operating the induction motor, the mechanical strength can be improved.

Further, when slots having a large slot area are formed at both ends of the rotor core, the end rings can enter the slots and the mechanical strength of the end rings can be improved. Further, by increasing the thickness of the aluminum coating on the outer peripheral side of the slot of the bind bar, it is possible to provide an induction motor having good characteristics without reducing the starting torque.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a shape of a bar of a rotor of a squirrel-cage induction motor according to one embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing an axial section of a rotor of the squirrel-cage induction motor of the present embodiment.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a longitudinal sectional view showing a radial section of a rotor of a cage induction motor according to another embodiment of the present invention.

FIG. 5 is a sectional view taken along line AA of FIG. 4;

6 is a sectional view taken along the line BB in FIG. 4;

FIG. 7 is a longitudinal sectional view showing a radial section of a rotor of a cage induction motor according to another embodiment of the present invention.

[Explanation of symbols]

1 ... bind bar, 2 ... copper, 3 ... aluminum coating, 4
... reaction layer, 5 ... cage rotor, 6 ... rotor core, 7 ... slot, 8 ... shaft, 9 ... end ring.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mika Takahashi 7-2-1, Omika-cho, Hitachi City, Ibaraki Pref. Hitachi, Ltd. Power & Electricity Development Division (72) Inventor Keiji Arai Omika, Hitachi City, Ibaraki Prefecture 7-2-1, Machi-cho, Hitachi, Ltd. Power and Electricity Development Division (72) Inventor Shoji Senoo 7-1-1, Higashi-Narashino, Narashino-shi, Chiba Pref. Hitachi, Ltd. Industrial Equipment Division (72) Inventor Sato Kazuo Hitachi 1-1, Narashino-shi, Chiba

Claims (4)

[Claims] 1. A rotor of an induction motor having a cage rotor in which a secondary conductor is formed by aluminum die casting on a rotary core having a plurality of slots, wherein a bar of the secondary conductor of the cage rotor is: A copper bar is provided in the slot, the outer periphery of the copper is covered with aluminum, and the copper and aluminum are combined via a reaction layer to form a bind bar. The bind bar and the end ring are made of aluminum. A rotor of an induction motor, wherein a secondary conductor is formed by die casting. 2. A rotor of an induction motor having a cage rotor in which a secondary conductor is formed by aluminum die casting on a rotary iron core having a plurality of slots, wherein a bar of the secondary conductor of the cage rotor is: The outer periphery of copper is disposed in the slot, the outer periphery of copper is covered with aluminum, and the copper and aluminum are formed of a bind bar joined via a reaction layer. An induction motor rotor having an area larger than a central slot area, and a secondary conductor formed by connecting the bind bar and the end ring by aluminum die casting. 3. The induction motor rotor according to claim 1, wherein a cross-sectional shape of the bind bar is substantially the same as a cross-sectional shape of the slot. 4. The induction motor rotor according to claim 1, wherein an aluminum coating on an outer peripheral side of the slot is formed thicker than an inner peripheral side.