JPH033459B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotor for an induction motor, and particularly to a rotor suitable for an induction motor driven by a distorted wave power source such as an inverter output.

[Conventional technology]

In general, induction motor rotors are roughly divided into three types: wound type, squirrel cage type, and block type. Of these, squirrel cage type rotors are the most widely used because they are robust, inexpensive, and have good electrical characteristics. It is used. However, this squirrel cage rotor has the drawback of high electromagnetic vibration noise. This is because, as shown in FIG. 1, the spatial harmonic magnetic flux generated by the slot of the stator 1 and the arrangement of the primary winding 2 wound within the slot enters the rotor 4 via the air gap 3. However, a harmonic current is induced in the rotor conductor 5 in the slot provided on the outer periphery of the rotor, and the resulting harmonic magnetic flux and the harmonic magnetic flux generated by the rotor slot generate harmonic electromagnetic flux on the stator side. This is because it acts as a force. Conventionally, as a means to suppress this electromagnetic force, the rotor conductor was skewed to cancel out the spatial harmonic magnetic flux that most affects electromagnetic vibration noise. However, in recent years, the speed of induction motors has come to be controlled by variable frequency power sources such as inverters. Since an inverter power supply is usually constructed from a semiconductor circuit, the output voltage or current is a non-sinusoidal wave. For this reason, the magnetic flux of an induction motor that uses this output has more harmonics than a sine wave power supply, and the traditional method of skewing the rotor conductor can only cancel out specific harmonics. Since the level of harmonic magnetic flux remains, electromagnetic vibration noise increases.

On the other hand, since the block type rotor does not have slots on the rotor's outer periphery, harmonic magnetic flux is not generated by the slots, and the entire rotor serves both as an iron core for passing magnetic flux and as a conductor for passing current. Since the surface serves as a current path, harmonic current flows to cancel the harmonic magnetic flux from the stator. Tests have confirmed that the electromagnetic vibration noise is extremely low even when actually driven by an inverter power source. However, the block-shaped rotor has the disadvantage that its electrical characteristics are inferior to that of the squirrel-cage rotor. Because the block-shaped rotor is made of a single material, the magnetic permeability in the radial and circumferential directions of the iron core is the same, and the magnetic flux does not penetrate deeply in the radial direction, but instead flows in the circumferential direction of the rotor surface through the shortest distance. It is for flowing. As a result, the cross-sectional area of the core conductor that intersects with the magnetic flux becomes narrower, increasing the current density, generating heat due to resistance loss in that area, increasing the effective resistance, and decreasing the output due to the decrease in rotor current. It becomes.

For this reason, a rotor as shown in FIG. 2 has been proposed which incorporates only the advantages of the squirrel cage and block type rotors. This has an inner shell 6 that allows only magnetic flux to pass through,
The rotor is composed of an outer skin 7 which is an effective part that generates tonk.

Although the inner shell 6 is simply made of thin magnetic iron plates laminated in the axial direction, the outer shell 7 is unique. The outer skin 7 has a large number of magnetic fine wires 8 made of iron or the like with a diameter of about 0.5 mm arranged approximately radially around the entire circumference of the rotor, and a highly conductive material 9 such as aluminum is placed in the gaps between the magnetic fine wires 8. Pour and form into a cylindrical shape.
As a result, the magnetic flux incident on the rotor is
Since the conductive material 9 can be guided by the conductive material 9 and penetrate deeply into the inner shell 6, the cross-sectional area of the conductive material 9 interlinked with the magnetic flux becomes large, and electrical characteristics close to those of a squirrel cage rotor can be obtained.

[Problem to be solved by the invention]

However, this type of rotor has the following problems in manufacturing. This is because the melted conductive material 9 is poured into a narrow space between a large number of magnetic fine wires 8, so that "s" are likely to be formed everywhere. Therefore, there was a drawback that the electrical resistance of the conductive portion increased and the electrical characteristics deteriorated. Furthermore, since the conductor is exposed on the surface of the outer skin, harmonic eddy current loss due to magnetic flux such as magnetomotive force of the stator winding and slot ripple is large, resulting in a reduction in efficiency.

It is an object of the present invention to provide a rotor for an induction motor of this type in which no holes are formed in the conductor part, that is, no increase in electrical resistance and no eddy current loss occurs on the surface of the outer skin as in the conventional case. be.

[Means to solve the problem]

To achieve this objective, the present invention provides a cylindrical effective portion, for example, the outer skin, with a large number of magnetic thin wires extending in the radial direction, a large number of highly conductive thin wires extending in the axial direction, and each of these thin wires. It is characterized in that it is composed of a binding material that connects the fine wires together.

[Effect]

By employing the above configuration, it is possible to suppress an increase in the electrical resistance of the conductive portion due to the "s" that tend to be formed on the outer skin of the rotor.

In other words, in addition to the conductive part that may become a resistance, a large number of fine conductive wires extending in the axial direction are provided, so that the induced current generated by the magnetic flux is
It flows through the fine conductive wire.

〔Example〕

Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

FIG. 3 is a cutaway perspective view of a main part of a rotor according to an embodiment of the present invention, and 7 in the figure is an outer skin. This outer skin 7
A thin magnetic wire 8 made of iron or the like with an outer diameter of about 0.5 mm extending in the radial direction and a fine conductive wire 10 made of copper or the like with an outer diameter of about 0.5 mm extending in the axial direction are attached to the entire outer shell. A large number of wires are arranged around the circumference, and a bonding material 11 such as a synthetic resin is injected into the gap between the thin wires 8 and 10 to form them integrally. Short-circuiting rings 12 are attached to both ends of the fine conductive wire 10 to electrically short-circuit them over the entire circumference.

Here, the fine wires 8 and 10 are as shown in FIG. 4a,
The wires are assembled in a lattice shape so that the fine conductive wires 10 are arranged in the axial direction and the magnetic fine wires 8 are arranged in the radial direction. The fine conductive wire 10 is bent many times in the direction of the thin wire 10 and arranged in the circumferential direction of the outer skin. 6 is the inner shell, which is made of thin magnetic iron plates laminated in the axial direction. The outer skin 7 and the inner shell 6 are tightly fitted, and the inner shell 6 is fixed to the shaft 13 at its axial center.

In the rotor of the present invention constructed in this way, the group of fine conductive wires acts as a conductor for guiding the induced current flowing on the surface of the rotor. ” is suppressed,
Consequently, there is no increase in electrical resistance, and a decrease in output can be prevented.

Although the outer diameter of the fine wires 8 and 10 is described here as approximately 0.5 mm, it is of course possible to make the wires even thinner within the range of manufacturing possible without being forced to stick to this outer diameter. .

Further, although the thickness h of the outer skin 7 is not specified here, it should be selected within a range that provides sufficient electrical characteristics in steady state.

Next, when forming a wire assembly of fine wires 8 and 10 shown in FIG. Either the upper part, that is, the outer peripheral side of the rotor is denser than the lower part, that is, the inner peripheral side, or the fine wire 10 of the upper part A is made of brass, and the fine wire 1 of the lower part B is made denser.
By arranging fine conductive wires 10 with high resistivity toward the upper layer, as in the case of arranging copper wires 10, starting characteristics can be improved.

〔Effect of the invention〕

As explained above, according to the present invention, the cylindrical effective part, that is, the part that becomes the conductor, has a
It is possible to obtain a rotor for an induction motor of this type, which does not cause any increase in electrical resistance and does not cause eddy current loss on the surface of the outer skin, unlike conventional ones.

[Brief explanation of the drawing]

Fig. 1 is a schematic development view showing a rotor of a conventional induction motor, Fig. 2 is a cutaway perspective view of a main part of a rotor of a recently proposed induction motor, and Fig. 3 is a diagram showing an embodiment of the present invention. A cutaway perspective view of the main parts of the rotor of an induction motor,
Figures 4a and 4b are diagrams showing an example of a fine wire set used in the rotor according to the present invention and an explanatory diagram of its manufacture;
The figure is a diagram showing another embodiment of the fine wire set used in the rotor according to the present invention. 6... Inner cylinder, 7... Outer cover, 8... Magnetic fine wire, 10...
Good conductive thin wire, 11...Binding material, 12...Short ring.

Claims (1)

[Claims] 1. A cylindrical effective portion having magnetism and conductivity, an inner body disposed inside the cylindrical effective portion and made of a magnetic material, and an inner body electrically connected to the cylindrical effective portion. In the device with a short-circuited portion at both ends, the cylindrical effective portion is formed by a large number of magnetic thin wires extending in the radial direction, a large number of highly conductive thin wires extending in the axial direction, and each of these thin wires. A rotor for an induction motor, characterized in that it is composed of a binding material that is integrally joined. 2. Claim 1 provides that the large number of fine electrically conductive wires are arranged so that the electrical resistance in the axial direction of the cylindrical effective portion is greater on the outer circumferential side than on the inner circumferential side. Characteristic induction motor rotor. 3. The guide according to claim 1, wherein the large number of fine electrically conductive wires are arranged densely on the inner circumferential side of the cylindrical effective part and sparsely on the outer circumferential side. rotor of an electric motor.