JPS6252545B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a double cage cast aluminum rotor for an induction motor.

For conventional double cage induction motors, the following methods are available to increase the ratio of starting torque to starting current, that is, starting efficiency. For example, as shown in Fig. 1, which is an enlarged front view of the main part of the punched fully closed groove double cage rotor core, the cross-sectional area of the upper conductor formed in the upper groove 1 is made smaller so that the secondary side at startup Increase the resistance or
Alternatively, the magnetic permeability is selected to be large by narrowing the width H of the slit connecting the upper groove 1 and the lower groove 3 or by increasing the height of the slit 2. Especially for models with 2-pole or 4-pole medium or large-capacity induction motors, the upper groove 1 is
It is necessary to have a cross-sectional area of several to more than ten mm ² and a slit width H of about 1 mm. However, even if molten aluminum is poured into the grooves of such a double-cage rotor core, the laminated central part of the rotor core, as shown by the cutout diagonal lines in the side view of the upper half of the cast rotor core in FIG. There is a tendency for molten aluminum to be difficult to be poured into the slit 2 portion in the vicinity.

If there is no aluminum in this slit 2, the following problems will occur. That is, the aluminum in the slit 2 constitutes a part of the upper conductor as a conductor,
When the induction motor is started, a starting current naturally flows through the conductor within this slit 2. For this reason, slit 2
This is because if the aluminum (conductor) inside is missing, the upper conductor will be subjected to a higher load and the heat capacity will be insufficient, and if the number of activations increases, there is a risk that the aluminum of the upper conductor will melt and wear away.

On the other hand, the reason why it is difficult to cast is that the flow of molten aluminum during casting is as shown by the arrow from the sprue 4 to the end ring 5, 5a where the flow resistance is lowest, and then to the lower groove 3.
The lower conductor is formed by casting, and the molten aluminum flows from both ends of the rotor core toward the center of the core, filling the upper grooves 1 and slits 2. However,
Among 2-pole and 4-pole, high-capacity induction motor models have a large rotor core length L, so the lower groove 3 and upper groove 1
While passing through the rotor core, the molten aluminum is absorbed by the rotor core and solidifies. In particular, the molten aluminum passing through the short-circuit ring 5a on the opposite side of the sprue has a large wetted edge (the length of the wall in contact with the fluid) with the walls of the lower groove 3, upper groove 1, slit 2, etc., which are the runners, so the flow resistance is The pressure decreases greatly, and the temperature also decreases sharply, making it difficult to pour molten aluminum into the slit 2 near the center of the rotor core.

The range in which molten aluminum can be cast into the slits 2 of the rotor core is investigated using a certain casting machine in terms of the relationship between the slit width H and the core length L, as shown in FIG. In the figure, the castable area is indicated by O, the uncastable area is indicated by N, and the boundary area line is indicated by R.According to research, the narrower the slit width H and the larger the core length L, the greater the uncastable area. These are the experimental results, and the cast-in rotor core that we developed this time corresponds to that.

The present invention has been made in view of the above circumstances, and an object of the present invention is to manufacture a casting rotor that is capable of casting molten aluminum into the narrow and vertically long slits of a double cage aluminum casting rotor. do.

An embodiment of the present invention will be described below with reference to FIGS. 1, 4, and 5.
This will be explained with reference to Figures A and B. Fig. 1 is an enlarged front view of the essential parts of a fully closed groove double cage type rotor iron plate, Fig. 4 is a side view of the upper half of the rotor core showing an embodiment of the present invention, and Fig. 5A is a top view of the rotor iron plate. FIG. 5B is an enlarged cross-sectional view of a fully closed deep groove having triangular parts and a generally rhombic shape as a whole, and FIG. 5B is an enlarged cross-sectional view of a substantially rectangular groove having a triangular head. Note that parts that are the same as those in the prior art will be explained using the same reference numerals. In the figure, a prescribed number of completely closed groove double cage rotor iron plates 10 (hereinafter referred to as iron plates 10) shown in FIG. 1 are laminated. Then, between these laminated layers, Figure 5 a, b
A rotor core 14 is formed by inserting a laminated body 13 in which a specified number of iron plates 12 having fully closed deep groove grooves 11 shown in FIG. Subsequently, this rotor core 14 is fitted into a casting mold (not shown) to cast molten aluminum (at one location approximately in the center in FIG. 4).

Next, the effects of the present invention will be explained.
The molten aluminum poured from the sprue 15 advances in the direction of the arrow a, forming a short-circuit ring 5 on the sprue side while being divided into the upper groove 1 and the lower groove 3 (most of it goes to the lower groove 3), and on the way it flows into the groove 11 of the laminate 13. While also being cast, the short circuit ring 5a on the side opposite to the sprue and the lower conductor are formed. During this process, molten aluminum is also cast into the upper grooves 1 and slits 2 near both ends of the rotor core 14.
On the other hand, since the grooves 11 of the laminate 13 have a larger area than the lower grooves 3 and the upper grooves 1, the flow resistance is smaller.
The molten aluminum separated from the groove 11 is indicated by the arrow C.
As shown in FIG.
The liquid flows inside the slit 2, joins the flow from both ends, and fills the slit 2 as well.

By arranging the laminated body 13 having this groove 11, the molten aluminum diverted from the lower groove 3 has fewer wetted edges than the molten aluminum flowing through the counter sprue, and the groove 11 has a larger area than the lower groove 3 and the upper groove 1. Therefore, the pressure drop and temperature drop are small, and the slit 2 near the center of the rotor core 14 can be completely filled. For this reason, the aluminum in the slit 2 acts as a conductor, increasing the heat capacity of the upper conductor, and even if the induction motor is started more frequently, there is no risk of the upper conductor being melted, and the reliability of the conductor allows it to rotate. As a result, the reliability of the induction motor improves.

The changes in the characteristics of the induction motor according to this example are as follows. That is, in this embodiment, unlike the intermediate short-circuit ring, the rotor conductors of each of the plurality of double cage grooves are independent from each other, the area of the groove 11 is large, and the length of the laminate 13 is short. Therefore, in this embodiment, the resistance and reactance of the rotor conductor are reduced, and the rotor core 14 is made long, so the influence thereof is small.

In addition, in the above embodiment, there is 1 in the center of the rotor core 14.
Although the example in which two laminates 13 are sandwiched has been described,
When the length of the rotor core 14 is large, the laminated bodies 13 are arranged at intervals such that the laminated length of the punched plates 10 is 150 to 200 mm.

As described above, according to the present invention, a laminate of punched iron plates having fully closed deep groove grooves is interposed between the fully closed groove double cage rotor cores, so that molten aluminum is transferred from the grooves into the upper groove. By casting and flowing the molten aluminum into both ends of the rotor core, the molten aluminum is smoothly cast and filled into the slits and the double basket-shaped grooves of the entire rotor core.

[Brief explanation of the drawing]

Figure 1 is an enlarged front view of the main parts of a fully closed groove double cage rotor core, Figure 2 is a cross-sectional side view of the upper half of a cast rotor core showing the conventional aluminum casting method, and Figure 3 is a slit-shaped rotor core. Boundary area diagram showing each of the castable and uncastable areas, FIG. 4 is an upper half cross-sectional side view of a cast rotor core showing an aluminum casting method showing an embodiment of the present invention, and FIG. 5A , B is an enlarged front view of the main part of the groove of the fully closed deep groove type. 1...Top groove, 2...Slit, 3...Bottom groove, 1
0...Fully closed groove double cage rotor iron plate, 11...Groove,
12... Iron plate, 13... Laminated body, 14... Rotor core.

Claims (1)

[Claims] 1 In the double cage cast rotor of an induction motor,
One laminate in which iron plates with fully closed deep groove grooves are laminated between the rotor cores, which are laminated with fully closed groove double cage rotor iron plates having narrow width and vertical slits connecting the upper and lower grooves. Or a rotor for an induction motor, characterized in that a plurality of rotors are inserted and molten aluminum is cast into each of the grooves and slits.