KR970001865Y1 - Rotor of an induction motor - Google Patents

Abstract

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Description

Rotor of induction motor

1 is a schematic diagram showing a conventional induction motor structure.

2 is a cross-sectional view showing a state in which an aluminum conductor is cast on a laminated core of a rotor.

3 is a plan view showing an outermost core sheet having exhaust holes according to the present invention.

4 is an enlarged cross-sectional view of a core sheet exhaust hole for explaining the operation of the present invention.

5 is a plan view showing another embodiment of the outermost core sheet having the exhaust hole according to the present invention.

6 is a plan view showing a core sheet having a gas passage according to the present invention.

* Explanation of symbols for main parts of the drawings

20: conductor (of rotor) 22: lamination core (of rotor)

32, 42: core sheet

24: exhaust hole (of core sheet) 44: gas passage (of core sheet)

The present invention relates to a rotor of an induction motor, and more particularly to a rotor having a laminated core having an exhaust hole for discharging gas therefrom during casting of an aluminum conductor.

The rotor of a conventional induction motor is composed of a plurality of disk-shaped laminated cores having a plurality of holes and constituting a closed furnace, and an aluminum conductor for applying power to the outside of the laminated core is cast by a die casting casting method. do. However, it has been found that the aluminum conductor of the rotor produced by die casting has a large blow hole, a small pin hole, and shrinkage holes formed during solidification, which adversely affect the quality of the product. These increase the electrical resistance to increase the operating temperature when the motor is running, as well as problems such as excessive noise and poor vibration due to the radial weight asymmetry of the rotor.

In other words, when aluminum is dissolved, gas (H ₂ ) inevitably melts in the molten metal and aluminum oxide is mixed, and these gases are eluted again during solidification to form a pinhole in the product, and the oxide only reduces the flow of the molten metal. Rather, it remains inside the casting, reducing its electrical resistance and mechanical strength.

These pores occur because the gas does not completely escape during filling of the cavity of the die in the melt filling phase of casting. Analysis of the finished aluminum conductor found that many defects occurred in the thickest part of the casting. For example, in the case of an ideal die design, an exhaust hole through which gas can escape should be formed, and the formation position will be most suitable between each component constituting the die. However, it is virtually impossible to form an exhaust hole by the joining of both the laminated core of the rotor and the conductor, which is an aluminum casting, which causes a large number of defects due to the gas gathered therein. Thus, there is a need to form exhaust holes between the laminated core and the aluminum conductor. This problem occurs more seriously in the production of large motors, it is difficult to use the die casting casting method for the formation of conductors in the production of large motors.

Accordingly, an object of the present invention is to provide a rotor having a laminated core having exhaust holes capable of eliminating defects generated during casting of an aluminum conductor.

Another object of the present invention is to provide a rotor having good conductivity by eliminating defects formed in an aluminum conductor and reducing noise generated by vibration.

Another object of the present invention is to provide a rotor that can use a die casting casting method in the production of a large motor by using a laminated core having an exhaust hole.

Objects of the present invention as described above are an induction motor including a laminated core composed of a plurality of core sheets laminated, a conductor molded by casting around the laminated core, and a rotating shaft fixed to the center of the laminated core. In the rotor, a plurality of rectangular exhaust holes penetrating the upper and lower surfaces are formed in two core sheets respectively located on the upper and lower outermost sides of the laminated core, and each of the two core sheets located inside and in contact with the two core sheets. The core sheet is in fluid communication with the exhaust holes of the two outermost core sheets, respectively, and a plurality of gas passages extending from the inner circumferential surface of each core sheet to the outer circumferential surface side are arranged in a radial manner so that the gas generated at the time of casting of the conductor is formed. Month by the rotor of the induction motor, characterized in that configured to be discharged to the atmosphere It is.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

Referring to FIG. 1, a schematic diagram of a typical induction motor 10 is shown. An induction motor is a typical AC motor, and only one of the rotor 12 or the stator 14 is connected to the power supply, and the other is operated by induction. The motor as shown is a three-phase induction motor, three windings 16 are fixedly installed around the stator 14, and have a laminated core (not shown) configured by stacking a plurality of core sheets. The rotor 12 is installed to rotate with it around the rotating shaft 18, and the conductor 20 which consists of aluminum is formed around the rotor 12 by the die-casting casting method.

FIG. 2 is a cross-sectional view of the aluminum conductor 20 of the rotor 12 in the state of die casting casting around the worm core 22. The conductor 20, which is an aluminum casting, is cast between the laminated core 22 and the die casting die 26, and a fixing member 28 is provided on the inner circumference of the laminated core 22 to prevent its radial movement. In general, in the case of die casting casting, an exhaust hole capable of discharging gas is formed, and in the related art, a plurality of exhaust holes 30 are formed to communicate with each other between the components constituting the die 26. However, as shown, the exhaust hole 30 is formed only between the components of the die 26, and the exhaust hole 30 is formed because both are bonded to each other between the aluminum conductor 20 and the laminated core 22. I could not.

Therefore, the pores 36 are generated in the aluminum conductor 20 because the gas of the portion is not discharged. In order to eliminate the pores 36, as illustrated in FIG. It may be the most effective way to form a plurality of exhaust holes 34 of a suitable size to allow gas to pass through the laminated core 22 but not to melt the aluminum so as to communicate with the 30.

On the other hand, the pressure of a press (not shown) transmitted to the portion of the pores 36 shown in FIG. 2 is Peff, and in the exhaust hole 30 of the die 26 for the flow of the molten aluminum (hereinafter, referred to as molten metal). The resistive force will be the sum of the frictional force, the shear force due to the viscous flow, and the surface tension between the interfaces. If the resistance to the flow of the molten metal is greater than the force by Peff, the molten metal cannot pass through the hole, and the gas in the cavity in the die 26 is pushed by the molten metal so that most of the gas passes through the exhaust hole 30. Will exit. The gas in the cavity can be discharged in this way, but it is a problem to discharge the gas surrounded by the melt inside the molten metal. If the flow of the melt is a laminar flow, the gas in the small bubble will not escape, but in the case of die casting, the speed of the melt flows through the cavity very quickly, so the flow of the melt becomes a turbulent flow, so the bubbles inside the melt The gas in it may exit through the vent hole 30 of the die 26 and the vent hole 34 of the laminated core 22.

3 shows a bore sheet 32 of a laminated core 22 having an exhaust hole according to the present invention. The core sheet 32 is located at the upper and lower ends of the laminated cores 22 shown in FIG. 2 and is the outermost core sheet 32 in direct contact with the aluminum conductor 20. As shown, a plurality of rectangular exhaust holes 34 penetrating the upper and lower sides of the laminated core 22 are appropriately arranged radially. Since the exhaust hole 34 has a portion where the molten aluminum is thickly formed near the outer circumference of the laminated core 22, it is preferable that the exhaust hole 34 is concentrated in the outer side of the core sheet 32.

On the other hand, the size of the exhaust hole 34 is the pressure Peff of the press, the area AP where the molten metal contacts the die 26, the friction force between the molten metal and the surface of the die 26, and the laminated core. It can obtain | require from the relationship of the contact area Af of the surface of (22), a molten metal, and the viscosity (micro: viscosity) of a molten metal.

Referring to FIG. 4, a process of obtaining the width W of the exhaust hole 34 of the core sheet 32 of the present invention will be described.

The force exerted by the press is PeffAp;

The force resisted by the exhaust hole 34 is

(i) friction between the surface of the laminated core 22 and the melt 24

Pfriction X contact area (A _f ) ₌ K ₁ A _f

Where K1: constant

: Coefficient of friction

(ii) Shear force due to viscosity (μ: viscosity) of the molten metal 24

K2 μ γ2AS

Where K2: Shape factor μ: Viscosity factor

AS: Shear Area γ: Shear Stress

(iii) surface tension between each interface

PS = γFe -A ℓ-(γFe -Gas + γAℓ-Gas Sin θ)

Thus, the balance of power becomes

Peff AP = K1 A _f + K2μ γ2AS + PS

Here, when analyzing the force of the exhaust hole 34, the length (l) is very long compared to the width (W) of the exhaust hole 34, but the effect on it is substantially the width (W) of the exhaust hole 34 Is determined by Therefore, it can be expressed as a function of the width W of the exhaust hole 34 per unit length (1 cm).

Ie A _P WX1cm Invar, A _P Since it becomes W, the width of the exhaust hole 34 W = (K1 A _f + K2μ γ ² As + Ps) / P _eff .

When the rough constants of various materials and the pressure of a general press are calculated by the above equation, the width W of the exhaust hole 34 is about 0.1 mm to 0.2 mm in the case of aluminum casting.

Meanwhile, another embodiment of the present invention is shown in FIG. 5, which is a configuration in which the plurality of exhaust holes 40 are formed in an arc shape and arranged along the circular direction of the core sheet 32 in the above-described embodiment of FIG. 3. to be. The exhaust hole 40 is also preferably concentrated in the outer portion of the core sheet 32 in which the conductor 20 is formed thick, and the width W is also based on the above equation.

The remaining task now is to take the gas that has passed through the outermost core sheet 32 into the atmosphere. This problem can be solved by placing the core sheets 42 as shown in FIG. 6 next to the outermost core sheet 32, respectively. As shown, the core sheet 42 next to the outermost core sheet 32 of the laminated core 22 is guided such that gas passing through the exhaust holes 34 and 40 of the outermost core sheet 32 is discharged. A plurality of gas passages 44 are arranged radially. The gas passage 44 preferably extends from the inner circumferential surface of the core sheet 42 to the outer circumferential surface side thereof so as to communicate with the exhaust holes 34, 40, from the inner circumferential surface of the core sheet 42 to the position where the exhaust holes 34, 40 are formed. The width is also based on the above equation.

Accordingly, the present invention provides the outermost core sheet of gas generated in the molten aluminum by placing the core sheets 42 as shown in FIGS. 3 or 5 and 6 on the outer sides of the laminated core 22, respectively. After passing through the exhaust holes 34 and 40 of 32, it is possible to discharge to the atmosphere through the gas passage 44 of the inner core sheet 42.

Claims (4)

(Correct) The rotor of an induction motor comprising a laminated core composed of a plurality of core sheets laminated, a conductor molded by casting around the laminated core, and a rotating shaft fixed to a center of the laminated core. A plurality of rectangular exhaust holes 34 and 40 penetrating the upper and lower surfaces are formed in two core sheets 32 respectively positioned at both outermost sides of the core 22, and are formed inside the two core sheets 32. In fluid communication with the exhaust holes 34 and 40 of the two outermost core sheets 32 respectively positioned and in contact with the two core sheets 42, from the inner circumferential surface of each core sheet 42 to the outer circumferential surface side thereof. A plurality of extending gas passages (44) are formed in a radial arrangement, the rotor of the induction motor, characterized in that configured to discharge the gas generated during the casting of the conductor (20) to the atmosphere. (Correction) The method according to claim 1, wherein the exhaust holes 34 and 40 of the two core sheets 32 are formed in a linear manner to be discharged radially or are formed in an arc shape and arranged in the circumferential direction thereof. Rotor of induction motor. (Correction) The width W of the exhaust holes 34 and 40 according to claim 1 or 2, wherein W = (K1 Af + K2μ γ ² As + Ps) / P _eff Where K1: constant : Coefficient of friction Af: Contact area (between laminated core surface and molten metal) K2: Shape Factor μ: viscosity of melt γ: shear stress AS: Shear Area PS: Surface tension (between each interface) Peff: Press Force The rotor of the induction motor, characterized in that can be obtained by. (Correction) The rotor of an induction motor according to claim 3, wherein when the conductor 20 is an aluminum casting, the width W of the exhaust holes 34 and 40 is approximately 0.1 mm to 0.2 mm. .