JPH03183343A - rotating electric machine - Google Patents

Abstract

PURPOSE:To enable high-speed operation by putting the dimension of the inside diameter of a rotor, which is made by setting a winding where aluminum alloy is die-casted in each slot of an iron core where silicon steel plates are stacked, to the 50% or less of the outside diameter. CONSTITUTION:Silicon steel plates are stacked to constitute a rotor iron core 11. To the outside diameter of the rotor iron core 11, the inside diameter for insertion of a rotary shaft 14 is made 50% or more of the outside diameter. Moreover, an inslot conductor is constituted by die-casting aluminum alloy, and at both ends are fused together short-circuit rings 13. For the in-slot conductor 12, the bottom 12a is positioned at the place several mm apart in outside diameter direction from the inside periphery of the iron core 11, and the circumferential width is extended in the circumferential direction as far as possible to enlarge the slot area. Hereby, a dynamo-electric machine, which withstands high-speed rotation and is firm and of high output, is manufactured at good yield rate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a rotating electric machine having a cage-shaped mass rotor, and is particularly effective in terms of mechanical strength when used in a high-frequency mode that rotates at high speed.

[Technology coming to i]

In the conventional rotor, the conductor and the short-circuit ring were die-cast by using an alloy of aluminum and magnesium for the conductor poured into the rotor slot.

On the other hand, the laminated core is made of silicon steel plate with a tensile strength of 55 kg/mm2 and carbon tool steel (S
K 5 ) thin plates were used, and each steel plate was stacked alternately. The purpose of this is to create a composite structure by stacking thin steel plates with high tensile strength alternately and die-casting, which combines the tensile strength of the art materials.
The object of the invention was to provide a rotation 'f having a tensile strength at least greater than the tensile strength of the attachment. Generally, it is desired that the inner diameter of the high frequency mode C) trochanter core be as large as possible. The reason for this is that the rotor shaft is made as thick as possible to provide a rotor with high shaft rigidity. Therefore, in the prior art, the rotor was designed so that the inner diameter was 50% or more of the outer diameter. If you look at the ratio of the inner diameter to the outer diameter of the rotors that have been manufactured so far, you will find that the inner diameter is at least 50% of the outer diameter.
% or more. In general, the critical speed for shaft deflection depends on the rigidity of rotating body components such as the shaft, bearings, and shaft support brackets, and the bearing span, but when considering the rigidity of the rotor itself excluding these components, the above 50%
The above ratio is an important technology that guarantees stable high-speed operation. However, even using this conventional technique, it was not possible to rotate the rotor at a peripheral speed exceeding 180 m/j due to the mechanical strength limitations of the iron core material and die-cast material that constitute the rotor.

[Problem to be solved by the invention]

i, ″fL The previous technology had the following problems.

(1) If the inner diameter of the rotor is increased to 50% or more of the outer diameter, the circumferential speed cannot exceed 1BOn per second, and therefore it has not been possible to meet market needs.

(2) Since the structure is complex, consisting of lamination of different types of steel plates, the lamination work is not simple and the work is not rational.

(3) Carbon tools require hardening to obtain tensile strength and are expensive.

(4) Is the carbon tool used to obtain strength?i
5 Li! compared to silicon steel plate! There were problems such as poor air characteristics, increased iron loss due to high frequencies, poor efficiency, and increased rotor temperature.

(5) During die-casting, pressure is applied to the stacked N core in the stacking direction, but since different materials with different tensile strengths are alternately combined, when the pressure is applied, the reaction force acting on the drawing materials is different. A gap was created between the bars, which caused the problem of bar breakage in which the slot conductor was cut.

(6) Conventional aluminum and magnesium alloys have the disadvantage that their tensile strength rapidly decreases as the temperature rises, and for this reason, it has been impossible to manufacture high-output rotating electric machines in which the rotor temperature inevitably increases.

(7) On the other hand, this aluminum and magnesium alloy has excellent mechanical strength below a certain temperature, but this property manifests itself in poor circulation of the metal, making it easy for casting cavities to occur, resulting in defective cavities and poor yields. Ta.

An object of the present invention is to solve the problems of the prior art and provide a rotating electric machine that rotates stably at high speed and has high output.

[Means to solve the problem]

In order to achieve the above object, the present invention is designed such that the inner diameter of the rotor is at least 50% of the outer diameter.

Furthermore, since the rotor circumferential speed exceeds 180 m/s and reaches 200 m/s, the rotor core and zero winding are made of the following materials.

(1) Silicon steel plates with higher tensile strength than conventional technology were used for the laminated core.

(2) For the winding, a die-cast material with tensile strength comparable to or higher than that of the conventional technology, with little loss of strength due to a 7g increase, and with good castability is used.

If the tensile strength of the silicon steel plate is increased, the magnetic properties will be lower than in the prior art, and the efficiency of the rotating electric machine will be lowered. Furthermore, since the material having the above property (2) has a slightly high specific resistance, this drawback can be solved by making the area of the rotor slot larger than in the prior art so as to reduce the secondary resistance.

[Effect]

(1) In order to maintain rotor rigidity equal to or higher than that of the prior art, it is a necessary condition that the ratio of the rotor inner diameter to outer diameter be 50% or more. If the ratio is lowered in order to increase the circumferential speed, the rotor critical speed will decrease and the objective cannot be achieved. Therefore, in order to increase the circumferential speed while maintaining the above ratio, a silicon steel plate having a tensile strength 1.36 times higher than that of the conventional technique was used.

(2) Instead of laminating two types of thin steel plates with different tensile strengths, one type of silicon steel plate with a constant tensile strength was used to obtain fJI/l.

(3) To improve efficiency, the width of the slot in the circumferential direction was increased to increase the slot area.

(4) On the other hand, as a die-casting material, we focused on aluminum alloy die-casting. This material has the property that its mechanical strength does not decrease much due to temperature rise, and it also has good castability.

The material also has a slightly lower electrical resistance (about 2%) than the conventional aluminum-magnesium alloy. In addition, by increasing the slot area in item (3) above, the secondary resistance becomes smaller.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS. 1 to 5.

FIG. 1 shows the rotation ff18! according to this embodiment. An example of applying this to a machine tool is shown below. In this embodiment, as a machine tool, the rotating electrical machine of this embodiment is embedded in the main shaft of an internal grinder that requires high-speed rotation.

1 is the main shaft body, 2 is the stator of the rotating electrical machine, 3 is the rotor of rotation 7, 4 is the shaft, 4a is the grindstone, 5 is the bearing, 6a, 6b are the brackets!・, 7 indicates preload splash.

The main shaft of the grinding machine has a built-in rotating electric machine (in this case, an induction motor) that directly drives the shaft 4.

The shaft 4 is mounted with an interference fit on the inner diameter of the rotor 3 according to the invention. Further, the shaft 4 is rotatably supported by a bearing 5, and a constant preload is constantly applied to the bearing by a preload spring 7 to increase its rigidity.

Is the critical speed for shaft deflection largely due to the rotor's inner diameter? The value increases in proportion to the square of the value. In other words, increasing the shaft diameter will increase the critical speed and widen the rotation range of the main shaft. On the other hand, the stress due to the centrifugal force acting on the rotor is larger at the inner circumference of the rotor, so if the inner diameter is increased, the critical speed increases, but the stress due to the centrifugal force increases, and in the conventional technology, the rotor The peripheral speed was limited to 180 m/sec due to the strength of the materials constituting it.

Figure 4 shows the relationship between the rotor inner diameter and the allowable rotation speed.

Shown in a'. Also, the relationship between rotor inner diameter and critical speed, b
' Shown in '. When a and b are according to this example, a" and b
' indicates the conventional one.

As shown in FIG. 4, it is best to select and use a rotor with an inner diameter that meets the allowable rotational speed and the critical speed for deflection of the shaft. According to this embodiment, the point where the allowable rotational speed intersects with the critical speed can be set higher than in the conventional case with the same inner diameter dimension.

In this embodiment, in order to provide a rotating electric machine as described above, a rotor is constructed by a method described in detail below.

Fig. 2 shows a cage-shaped mass rotor 3 of a rotating electric machine according to this embodiment.
shows. FIG. 3 shows a side cross section of the rotor.

11 is a rotor core, 12 is a conductor in the slot, 13 is a short circuit ring, and 14 is a rotor shaft. The iron core No. 11 is made of a laminated high tensile strength silicon steel plate whose inner diameter is at least 50% of the outer diameter of the rotor, and whose tensile strength is greater than that of the conventional technology. Rotor shaft J4 is connected to shaft 4.

In this example, the conventional technology 551 (g/mm2) is 751 (8 g/mm2).
A silicon steel plate with a tensile strength of / mm” was used.

The slot conductor 12 extends several rn from the inner periphery of the core in the outer radial direction.
The bottom 12a or 117 is placed at a distance of m, and the width in the circumferential direction is extended as much as possible in the circumferential direction, and the tooth width is reduced to the point where the magnetic flux density of the tooth is saturated fO. Next, for the conductor 2 in the slot, a material having a relationship between temperature and tensile strength as shown in FIG. 5 is used. In this example, aluminum alloy die casting was used.

According to FIG. 5, the conductor must be made of a material that exhibits almost no decrease in strength at temperatures up to 150°C. It is also necessary to have an appropriate TL resistance to generate torque as a rotor.

With the above configuration, it is possible to provide a durable and stable rotating electric machine even when the rotor rotates at a maximum circumferential speed of 9200 m/min.

〔Effect of the invention〕

According to the present invention, since the rotation speed is increased by 11% compared to the conventional technology, (1) it is possible to provide a highly reliable rotating electric machine that is robust, stable for a long period of time, even at a maximum circumferential speed of 200 m/s;

(2) Since the circumferential speed is increased, the size of the rotating electrical machine can be made larger than in conventional technology, resulting in high output (approximately 2 to 2
．． 5 times) rotating electric machines can be provided.

(3) Good castability during die casting eliminates the occurrence of casting cavities, eliminates manufacturing defects, and significantly improves yield.

(4) Since the iron core is constructed by laminating one type of silicon steel plate, the lamination work becomes simple and the cost becomes low.

(5) By stacking steel plates with different tensile strengths, the springback force generated is suppressed, so bar breakage does not occur and the yield is improved.

(6) When the rotating electric machine according to the present invention is used in a machine tool, a machine tool with good precision, high grinding speed, and increased grinding capacity can be provided.

(7) Since the allowable rotor temperature increases, the conventional rotor cooling stage (4) can be reduced and the air volume during operation can be reduced, contributing to energy saving.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the main shaft of an internal grinding machine to which a rotating electric machine according to an embodiment of the present invention is applied, FIG. 2 is a sectional view of a rotor according to this embodiment, and FIG. FIG. 4 is a characteristic diagram showing the internal diameter of the rotor and the rotation of the critical speed stage U'3'r, and FIG. 5 is a characteristic diagram showing the relationship between the growth and tensile strength of the rotor slot groove body. 11: Rotor core, 12 slotted conductor, 13th and black diagram 11 ◆ = 5L pregnant

Claims (1)

[Claims] 1. In a rotating electrical machine comprising an iron core formed by laminating steel plates, a winding die-cast from an aluminum alloy, and a rotor fitted to a rotor shaft, the rotor has an inner diameter. A rotating electrical machine characterized by being configured such that its dimensions are at least 50% or more of its outer diameter.