JPS604896B2 - electric motor rotor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a squirrel-cage rotor for an electric motor whose squirrel-cage winding is made of a novel aluminum-based alloy that has a low electrical resistivity, an even lower temperature coefficient of electrical resistance, and is suitable for die casting. .

Conventionally, aluminum has been used for the rotor conductor of induction motors.

However, pure aluminum has an electrical resistance temperature of 4.9 x 10-3 °C/°C at 200 oo, and the electrical resistance increases greatly as the temperature rises. For this reason, the temperature of the electric motor increases during operation due to Joule heat generation in the rotor conductor. Generally, electric motors are designed with a temperature increase in mind, and this temperature increase reaches a certain temperature when Joule heat generation during operation and heat radiation from the surroundings are balanced. Furthermore, if this temperature rise becomes too high, problems such as insulation will occur, so the motor body itself is designed to be large in order to increase heat radiation and keep the temperature rise as low as possible. Although the temperature rise of the electric motor is designed to be about 20,000 ℃ or less, it is obvious that simply increasing the size of the electric motor is not a good idea. From the above,
As a conventional rotor conductor member, it is important to treat pure A resin in some way to reduce its temperature coefficient of resistance as much as possible.

However, the electrical resistivity (hereinafter abbreviated as resistivity) of a conductor member with an improved temperature coefficient of resistance as described above is significantly higher than that of pure aluminum, and therefore, since the current flowing is constant, the Joule heat value increases, and the electric motor The rising temperature is 20
000, resulting in deterioration of the insulator used. Therefore, even if the temperature coefficient of resistance is small, a material with a large specific resistance results in a high level of temperature rise, which is not desirable. In other words, the improved conventional A〆 alloy has a relatively small resistance temperature coefficient, and has a relatively low temperature coefficient of resistance.
．． Examples include 8% Mg alloy and A-1.25% Mn alloy.

However, these resistivities are 30% higher than that of pure A or 5% higher than that of pure A.
The increase was 0%, and the temperature rise was large. An object of the present invention is to provide a squirrel-cage rotor for an electric motor with a low temperature rise, the squirrel-cage winding being made of an aluminum-based alloy that has a low resistivity, a low temperature coefficient of resistance, and is suitable for die casting. . In the present invention, it has been found that by adding 0.05 to 2.5% by weight of rare elements to aluminum, the temperature coefficient of resistance can be reduced without increasing the specific resistance, and this alloy can be used to die-cast squirrel cage windings. By doing this, we were able to obtain a squirrel cage rotor for an electric motor with a small temperature rise.

That is, it is clear that the temperature rise of the electric motor is largely related to the specific resistance of the rotor conductor, but it has been found that the temperature in particular is determined by the temperature coefficient of the specific resistance. Therefore, when comparing alloys having the same specific resistance at high temperatures, the smaller the temperature coefficient of resistance, the smaller the temperature rise, and the lower the temperature rise. The present inventors have focused on the fact that rare elements have the smallest temperature coefficient of resistance among metal elements.

As a result, the resistance temperature could be lowered by solidly dissolving the rare earth element in A. However, the amount of rare elements in solid solution is small compared to that of Al. For example, Ce is as small as 0.05% by weight at most. As a result of various studies, it was found that rare elements can be dissolved in supersaturated solid solution when molten metal is rapidly solidified as in die casting. Rare elements include: Ce, Pr, Nd, Pm, Sm
, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb,
Both of these were effective for the temperature coefficient of resistance. In addition, as a result of experiments with various contents, A
It has been found that when the finish contains 0.3 to 1.5% by weight of at least one of Ce, La, pr, Zd, etc., the temperature coefficient of resistance becomes 4.0 lower than that of pure A. 0.3%
At less than 100%, no significant solid solution effect of the rare elements was observed, and the change in the temperature coefficient of resistance was small.

Moreover, if it exceeds 1.5%, a large amount of eutectic intermetallic compounds of A and rare elements will crystallize in the structure, and the area of primary crystals (A solid solution) will decrease, resulting in a temperature coefficient of resistance. does not become smaller. In particular, a range of 0.3 to 1.5% by weight is extremely effective because the temperature coefficient of resistance is lowest. In addition,
In the case of compound addition, Mitsushmetal (I,
A similar effect can be obtained even if it is added to A in the form of a mixture of Ce, Nd, P, etc.

As a result, misch metal (La32.9%, Ce47
．． 1%, Nd 15%, Pr 5%), the amount added is 0.
It has become clear that 5 to 1.5% is appropriate. The alloy of the present invention has the above characteristics in a die-cast state.

The fluidity within the above composition range was almost the same as that of pure A powder, and the die-castability was also good.

Example 1 For melting, heat a graphite crucible to about 500 qo in an electric furnace, charge A-grade metal special 1 (99.90%), melt the ingot, raise the temperature to 800 qo, and then Cerium was added as an element by wrapping it in aluminum foil and held for 10 minutes, and then it was poured at 700:00 and die-casting was performed.

Similarly, conventional pure A-Mg-A-Mn alloys were melted and die cast. Table 1 shows the chemical composition (% by weight) of each alloy. The die casting properties of these alloys were as good as that of pure A alloys. Table 1, Figure 1 shows No. It shows a specific resistance (20°C) of 1 to 6.

The specific resistance gradually increases with Ce content;
85% is about 3〃○・佽. In addition, as mentioned above, the specific resistance of conventional alloys 7 and 9 is 31 Q·skin or more. Figure 2 shows the temperature at 20°C for each alloy shown in Table 1.
These are the results of measuring the temperature change in specific resistance from 220°C to 220°C.

No. 1 is Jun A Yu, No. 2, 3, 4, 5, 6 are A and -
It is a Ce alloy. Also, No. 7 is A Yuichi 0.8% Mg
, 8 is AZ-1.25**%Mn, 9 is A〆-3.5%
It is an Mg alloy.

As a result, No. 2, 6, 7, 8, 9 are NO. It is almost parallel to 1 pure A Yu. Compared to these conventional alloys, the alloy No. of the present invention. It can be seen that 5 has a clearly less complicated slope than the conventional one. Table 2 shows the specific resistance (20℃) and temperature coefficient of resistance (20~2
00oo).

As a result, it is clear that the temperature coefficient of resistance of alloys 4 and 5 of the present invention is as small as approximately 80% of that of pure A. Second
Table 3 shows the relationship between the temperature coefficient of resistance and specific resistance at 200° C. determined for each alloy from FIG. 2.

Invention alloy No. 4 and 5 are both conventional alloy No. 7
, 8, 9, and pure A when compared at the same specific resistance, it is clear that the temperature coefficient of resistance is smaller. This can clearly reduce the temperature rise of the squirrel cage motor.
Example 2 La was added as a rare element by the same melting method as in Example 1.
, Pr, Nd, Sm, and Yb.

Table 3 shows the chemical composition (wt%) of these alloys.The die-casting properties of these alloys were as good as that of pure A.Table 3 shows the temperature coefficient of resistance of these alloys as in Example 1. As a result of measuring, the specific resistance at 20℃ is 2.96
~2.95 French ○ skin, and resistance temperature coefficient is 3.82~3
．． It was 91 mm○ skin/00×10-3.

Example 3 Composite addition of rare earth elements was investigated using the same melting method and die casting as in Example 1.

The composite addition is misch metal (La32.9%, Ce47
．． 1%, Nd 15%, Pr 5%). Fourth
The table shows the chemical composition (% by weight) of these alloys. The die casting properties of these alloys were as good as that of pure A alloys. Table 4 Measure the specific resistance and temperature coefficient of resistance in the same manner as in Example 1,
The results are shown in Table 5.

As shown in the table, No. 1 of the invention alloys in Table 5. Nos. 15 to 17 all have a resistance temperature coefficient of 4.0 without increasing the specific resistance.
Since the temperature is as low as 14 x 10-3 or less, the temperature rise of the electric motor can be significantly reduced.

Example 4 Table 6 shows the invention alloy No. 5 shows the temperature characteristics of an electric motor using pure A at 200°C.The temperature rise of the motor of the present invention is 150°C, which is clearly 50°C lower than that of the conventional motor.

It is clear that reducing the temperature rise from 200 qo to 150 qo allows for miniaturization and increased output.
Note that it is clear that the present invention will exhibit similar effects even when A contains metals such as Mg, Mn, and Ti.

As shown in Table 6 and above, the present invention reduces the temperature rise of the electric motor by appropriately blending rare elements, and casts the squirrel cage winding using the above-mentioned alloy, which has excellent die-casting properties, resulting in high productivity.
It also has an excellent effect leading to a long lifespan.

[Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between the amount of cerium and resistivity, Figure 2 is a diagram showing the relationship between resistivity and temperature for various alloys, and Figure 3 is a diagram showing the relationship between resistivity and temperature coefficient of resistance for various alloys. A diagram showing the relationship and FIG. 4 is a diagram showing the relationship between the amount of cerium and the temperature coefficient of resistance. Nozomizu Shimuzu Bootsuzu 3rd illustration

Claims (1)

[Claims] 1 The total amount of one or more rare earth elements is from 0.3 to
A rotor for an electric motor, characterized in that a rotor conductor is cast from an alloy consisting essentially of 1.5% by weight and the remainder aluminum.