JPH0546782B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a rotor for an induction motor.

[Technical background of the invention and its problems]

The rotor core of an induction motor is generally made of laminated thin iron plates, but when the circumferential speed of the rotor is high as in ultra-high speed motors, the strength of the laminated iron core against centrifugal force is is insufficient, and a rotor with a block core is required. When a block iron core is used in an induction motor, there are the following two drawbacks.

(1) In principle, it is impossible for the rotor of an induction motor to rotate at a synchronous speed, and the rotation speed of the rotor lags behind the rotation speed of the magnetic flux. Therefore, the rotor is always interlinked with alternating current magnetic flux, and eddy currents are generated on the rotor surface, and the resulting resistance loss greatly deteriorates the efficiency of the motor compared to a laminated iron core. Furthermore, since the air gap between the stator and rotor is small in an induction motor, the eddy current due to slot ripple is also large. Eddy current is the seventh
As shown by arrow A in the figure, the current flows in the axial direction of rotor B, but at the end of the rotor it has no choice but to flow in the circumferential direction, and all the current is concentrated at the end of the rotor and generated in this part. The loss will be greater.

(2) The rotor of a squirrel-cage-wound motor has a conductor rod inserted into a slot in the iron core.It is best to place this conductor rod as close to the rotor surface as possible to reduce slot leakage reactance and improve motor characteristics. This is preferable in terms of improving. In the case of a rotor with a laminated core, the rotor core is formed by punching thin iron plates and laminating them to form the rotor core, so the slots can be made into a relatively arbitrary shape and have low leakage reactance. You can easily get slots. However, punching the core of a block core rotor is impossible, and it is difficult to create slots of arbitrary shapes.
Therefore, in the case of a block core, the shapes of the slot 1 shown in FIGS. 8 and 9 are conceivable. FIG. 8 shows a round slot that is penetrated in the axial direction of the iron core 2 with a drill or the like. This round slot 1 is relatively easy to manufacture, but in order to pass a drill through it, the bridge part 2a of the slot 1 must have a certain thickness for manufacturing purposes, so it should be made as thin as a laminated core. It is difficult to do this, the leakage reactance increases, and the motor characteristics deteriorate compared to the laminated core type. Furthermore, in the case of a large-capacity machine, the length of the iron core becomes long, making it difficult to penetrate the slot accurately, which causes rotor vibration during high-speed rotation, and in some cases makes operation impossible. Figure 9 shows that in order to reduce leakage reactance, the slot 1 is a round hole with a semi-opening part 1a cut from the surface of the core 2, but during high-speed rotation, a semi-opening part 1a is formed in the semi-opening part 1a. Due to the vortex of refrigerant,
Mechanical losses increase. Therefore, the next consideration is an open type slot 1 used in a cylindrical synchronous machine as shown in FIG. After the conductor rod 3 is housed in the slot 1, it is fixed with a wedge 4.
Since this slot 1 is formed by cutting from the surface of the iron core 2, the machining accuracy is good and the balance during high speed rotation is good. However, in order to withstand the centrifugal force acting on the conductor rod 3, the wedge 4 becomes thicker, so that the conductor rod 3 separates from the surface of the iron core 2, increasing leakage reactance and deteriorating the motor characteristics. Therefore, it is not preferable to use slot 3 in FIG. 10 as is.

[Purpose of the invention]

The present invention improves the characteristics of the motor by reducing the slot leakage reactance, and provides a block iron core rotor for induction motors that rotates at high speed with good balance, does not generate vibrations, and has less mechanical loss due to refrigerant vortices. The purpose is to provide.

[Summary of the invention]

In the present invention, in a block core rotor of an induction motor in which a squirrel cage winding is provided on a block core, the slot for storing the conductor rod of the cage winding is an open slot, and the upper part of the conductor rod is inserted into a wedge of the electric conductor. By fixing the wedge at By positioning a certain wedge at the slot opening, leakage reactance is reduced, mechanical loss due to refrigerant vortices is prevented, machinability is improved, and vibrations are prevented.

[Embodiments of the invention]

Embodiment 1 A first embodiment of the present invention will be described below with reference to FIGS. 1 to 3. Slot 1 is an open slot similar to that shown in FIG. A first squirrel cage winding 6 is formed by connecting end rings 5 to both ends of the conductor rod 3 housed in the slot 1. The conductor rod 3 is fixed to the surface of the iron core 2 with an electric conductor wedge 4. Both ends of the block iron core 2 are connected to conductor rods 3
A step 9 is provided by lowering the height to the height of the outer diameter side surface of the step 9, and a wedge end ring 7 of an electric conductor is fitted here. Both ends of the wedge 4 are connected to the wedge end ring 7 to form a second squirrel cage winding 8.
form.

Next, the effect will be explained.

Since the wedge 4 corresponding to the conductor rod of the second squirrel cage winding 8 is located at a position that coincides with the surface of the iron core 2,
Leakage reactance is reduced, motor characteristics are improved, and mechanical loss due to refrigerant vortex generation is also prevented. Furthermore, since the slot 1 can be manufactured by cutting from the surface of the massive iron core 2, the dimensional accuracy is long, the rotor is well balanced during high speed rotation, and the problem of vibration generation is eliminated. Since the wedge end ring 7 of the electrical conductor is fitted to the end of the rotor core where all the eddy current generated on the rotor surface is concentrated, no current flows through the end of the block core 2, and the wedge end Current flows through the loop ring 7, and compared to a general block core rotor, resistance loss at the rotor end is significantly reduced, improving motor efficiency.

Embodiment 2 Next, a second embodiment will be described with reference to FIGS. 4 to 6. This is because the wedge 4, which is the conductor rod of the second squirrel-cage winding 8, extends outward from the iron core 2 and is connected to the wedge end ring 7, and the first squirrel-cage winding 6
This embodiment differs from the first embodiment in that an insulator 10 is interposed between the conductor rod 3 and the wedge 4, and the rest is the same as the first embodiment.

In this way, most of the eddy current that is about to flow to the end of the block core 2 bypasses the wedge end ring 7, so in addition to having the same effect as in the first embodiment, the wedge 4
The brazing connection between the end ring 7 and the wedge end ring 7 becomes easy. In addition, since the insulator 10 is interposed between the conductor bar 3 and the wedge 4, when the insulator 10 is not present, the conductor bar 3 and the wedge 4
Sparks are generated due to contact and separation between the conductor rod 3 and the wedge 4.
It has the effect of increasing safety by preventing accidents that may cause damage.

Note that interposing the insulator 10 in the first embodiment may be applied.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to obtain a block iron core rotor for an induction motor that has low eddy current loss, low mechanical loss during high-speed rotation, and is well-balanced and generates little vibration.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional perspective view showing a main part of a first embodiment of a block core rotor for an induction motor according to the present invention, FIG. 2 is a vertical cross-sectional view of a main part of FIG. 1, and FIG. of-
4 is a cross-sectional perspective view showing the main parts of the second embodiment, FIG. 5 is a longitudinal sectional view of the main parts of FIG. 4, and FIG. 6 is a cross-sectional view taken along the - line in FIG. FIG. 7 is an explanatory diagram showing eddy currents in a conventional example, and FIGS. 8 to 10 are perspective views showing slot portions in different conventional examples. 1...Slot, 2...Iron core, 3...Conductor rod,
4... Wedge, 5... End ring, 6... First squirrel cage winding, 7... End ring for wedge, 8... Second squirrel cage winding, 9... Stage, 10... …Insulator.

Claims (1)

[Scope of Claims] 1. In a block core rotor of an induction motor in which a squirrel cage winding is provided on a block core, the slot for storing the conductor rod of the cage winding is an open slot, and the upper part of the conductor rod is an electric conductor. A block iron core rotor for an induction motor, characterized in that a second squirrel cage winding is formed by fixing the rotor with a wedge, and connecting both ends of the wedge with an end ring for the wedge. 2. A block core rotor for an induction motor according to claim 1, wherein the wedge end ring is fitted into a lower end of the block core. 3. A block iron core rotor for an induction motor according to claim 1 or 2, characterized in that an insulator is interposed between the conductor rod and the wedge.