JP2787984B2 - Rotor for squirrel-cage induction motor - Google Patents

Description

The present invention relates to a squirrel-cage induction motor, and more particularly to a rotor suitable for use in a squirrel-cage induction motor.

(Prior Art) Conventionally, in a squirrel-cage induction motor of this type, a disc-shaped electromagnetic steel sheet and a disc-shaped high-strength steel sheet are alternately laminated in a cylindrical shape, and each of the shaft holes is formed in the cylindrical laminated steel sheet. It is conceivable to employ a rotor constituted by press-fitting a rotating shaft coaxially through the shaft (see Japanese Patent Application Laid-Open No. 59-83827).

(Problems to be Solved by the Invention) In such a configuration, the mechanical strength of the high-strength steel sheet is much higher than the mechanical strength of the electromagnetic steel sheet. At the time of press fitting,
Even if the magnetic steel sheet yields and it is no longer possible to properly maintain the interference with respect to the rotating shaft, the high-strength steel sheet properly maintains the interference with the rotating shaft due to its high mechanical strength.
Therefore, even when the rotor rotates at a very high speed, the cylindrical laminated steel plate always rotates integrally with the rotating shaft.

However, since the high-strength steel sheet is a non-magnetic material, the magnetic properties of the above-described cylindrical laminated steel sheet are reduced by the number of laminated high-tensile steel sheets, compared to the case where the entire cylindrical laminated steel sheet is formed only of magnetic steel sheets. As a result, there arises a problem that the output efficiency of the induction motor is greatly reduced.

On the other hand, as shown in Japanese Utility Model Application Laid-open No. Sho 58-9045, the entire laminated steel sheet of the rotor is made of an amorphous magnetic material having both high mechanical strength and high magnetic properties. It is also conceivable to use a steel plate.

However, the magnetic properties of the amorphous magnetic material are significantly reduced when the amorphous magnetic material is strained. In addition, there is a problem that both the longitudinal elastic coefficient and the heat resistance of the amorphous magnetic material are low. Further, since the perpendicular bending strength of the amorphous magnetic material is low, there is a problem that a steel plate made of such a material is easily broken. Moreover, since the thickness of the steel sheet is as thin as several tens (μm), it is very difficult to handle.

However, due to the various disadvantages of the amorphous magnetic material described above, when pressing the rotating shaft into the cylindrical laminated steel plate made of the amorphous magnetic material, the interference of each steel plate is required for ultra-high-speed rotation. Even if it tries to secure as much as possible, each steel plate is subjected to a right-angle bending action by the press-fitting allowance, and is sheared without plastic deformation. Accordingly, cracks and the like remain inside each steel plate, which causes a problem that the cylindrical laminated steel plate is broken at a much lower rotation speed before reaching ultrahigh-speed rotation.

Accordingly, the present invention provides a squirrel-cage induction motor in which a rotor formed by effectively utilizing both characteristics of a material having a high magnetic property and a material having a high tension property in order to cope with the above. It is something to offer.

(Means for Solving the Problems) In solving the problems, the structural features of the present invention include a squirrel-cage induction motor comprising a rotating shaft which is coaxially fitted to the rotor body by press-fitting the rotor body. A plurality of disc-shaped magnetic steel sheets made of a high-strength magnetic material selected from a high-silicon magnetic steel sheet material containing about 6.5% by weight of an amorphous magnetic material or silicon. Along with coaxially laminating a plurality of disc-shaped high-tensile steel plates made of a high-strength material that can be press-fitted to a rotating shaft and having a higher perpendicular bending strength than the magnetic material, the coaxially mixed lamination was performed. The high-tensile steel plate is disposed at both ends, and short-circuit rings are further disposed on both outer sides thereof. The inner diameter of the magnetic steel plate is a (μm), and the outer diameter of the rotating shaft is b. (Μm) and the high-tensile steel plate When the inner diameter was c (μm), b + 10 (μm) ≧ a
Each dimension is set so that the relationship of ≧ b−10 (μm)> c holds.
a, b, c are defined.

(Function and Effect) By configuring the present invention as described above, it is possible to press-fit the rotating shaft into the rotor main body accurately while securing the original mechanical strength and high magnetic properties of each magnetic steel sheet. The rotor body is connected to the rotating shaft with a required interference only with each of the high-tensile steel plates,
Enables ultra-high speed rotation of the rotor.

In addition, since the high-tensile steel plates are arranged on both end sides that are coaxially mixed and laminated, and short-circuit rings are further arranged on both outer sides thereof, when the short-circuit rings are thermally joined by welding or the like. Or at the time of mechanical joining by caulking or the like, without causing crystallization due to high temperature of the material forming each magnetic steel sheet, or without giving mechanical strain to each magnetic steel sheet,
High magnetic properties unique to the material of each magnetic steel sheet can be effectively secured.

(Embodiment) Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an example of a rotor according to the present invention applied to a squirrel-cage induction motor, and the rotor has a cylindrical shape. The rotating shaft S is concentrically fitted into the center of the rotor main body R by press fitting. The rotor body R includes a plurality of annular plate-like high-tensile steel plates 10a,..., 10h made of a high-tensile material, and a plurality of annular plate-like magnetic steel plates 20a,.
, 20h, and these steel plates 10a, ..., 10h and 20a, ..., 20h are arranged in the order shown in Figs.
They are alternately coaxially and cylindrically stacked.

In such a case, the steel plates are alternately stacked in the order shown in FIGS. 1 to 3 for the following reason.

(1) In order to increase the output efficiency of the induction motor, the density of magnetic flux flowing from the stator of the induction motor into the rotor main body R should be maximized at the axial center of the rotor main body R in the coaxial direction. At the center, four magnetic steel plates 20c,..., 20f are arranged, and the remaining magnetic steel plates 20a, 20b, 20g, 20h are alternately axially respectively with the tensile steel plates 10c, 10d, 10e, 10f. They were arranged symmetrically.

(2) The amorphous magnetic material is weak to heat and crystallizes at a high temperature of 400 ° C. or higher. Therefore, as will be described later, the high temperature generated when the plurality of conductor rods 30,... 30, and both shorting rings 40, 50 are alternately joined by welding or brazing, etc., is generated by the magnetic steel sheets 20a,. And when using a mechanical joining method such as caulking, each magnetic steel sheet 20a,
In order to prevent the deterioration of the magnetic characteristics due to the distortion of 20h, a pair of high-tensile steel plates 10a, 10b, and 10g, 10h are respectively arranged at both axial ends of the rotor body R. did.

In addition, when the rotating shaft S is press-fitted into the rotor main body R, the shearing of the magnetic steel plates 20a,..., 20h predicted to occur due to the low right-angle bending strength of the magnetic steel plates 20a,. Each magnetic steel sheet to prevent fracture and residual strain stress
The inner diameter of 20a,..., 20h was determined as follows. Also,
Assuming this inner diameter dimension, each high-tensile steel plate 10a,.
・ The inner diameter of 10h was also determined as follows.

(1) If the inner diameter of each magnetic steel plate 20a,..., 20h is a (see FIG. 3) and the outer diameter of the rotating shaft S is b (see FIG. 1), a = b ± The inner diameter of each magnetic steel plate 20a,..., 20h is finished so as to be 10 (μm).

(2) Assuming that the inner diameter of each of the high-tensile steel plates 10a,..., 10h is c (see FIG. 3), each of the high-tensile steel plates 10a,. In order that the rotor main body R does not relatively rotate with respect to the rotation axis S even if the inner diameter increases, the inner diameter dimension c is set so as to secure a sufficient margin for the rotation axis S of each of the high-tensile steel plates 10a,. It is designed to be smaller than the outer diameter dimension b. In such a case, the inner diameter dimension c is obtained by subtracting from the outer diameter dimension b of the rotating shaft S the expansion allowance due to the centrifugal force determined based on the specific gravity, the Young's modulus, the outer diameter dimension, and the rotation speed of each of the high-tensile steel plates 10a,. Value.

, 10h, 20a,..., 20h (in FIG. 4, the respective insertion holes 11,.
, 30 are inserted through the respective conductor rods 30,..., 30 as shown in FIG. 1 and FIG.
As shown in FIGS. 1 to 3, short-circuit rings 40 and 50 are joined and connected to both ends of the 30 by welding, brazing, or the like while sandwiching the laminated steel sheet.

In the present embodiment configured as described above, as described above, as the laminated steel sheets of the rotor main body R, each of the high-strength steel sheets 10a,... Each of the magnetic steel plates 20a,..., 20h is adopted.
The inner diameter of a,..., 20h is substantially equal to the outer diameter of the rotating shaft S, and the inner diameter of each high-strength steel plate 10a,. In order not to cause relative rotation between the rotor body R and the rotation axis S even under the base centrifugal force, the press-fitting allowance of the high-strength steel plates 10a,. Therefore, each magnetic steel plate 20a,
.., The rotating shaft S can be properly press-fitted into the rotor main body R without incurring the disadvantages inherent in the material forming 20h.
As a result, the rotor body R is made of the high-tensile steel plates 10a,.
Only at 0h, the shaft is connected to the rotating shaft S with a required interference, and as a result, the rotor can be rotated at a very high speed.

Further, since the number of magnetic steel plates disposed at the axial center portion of the rotor main body R is increased as described above, the magnetic flux flowing into the rotor main body R from the stator of the induction motor is reduced by the axial center of the rotor main body R. As a result, the output as an induction motor can be appropriately secured in combination with the high magnetic characteristics inherent to the amorphous magnetic material. In such a case, the steel plate at the position where the short-circuit rings 40 and 50 are joined, respectively,
Each of the high-strength steel plates 10a, 10b, and 10g, 10h is used.
At the time of thermal joining by welding or the like or mechanical joining by caulking or the like, the material forming each magnetic steel sheet 20a,..., 20h does not cause crystallization due to high temperature, or each magnetic steel sheet 20a,. It is possible to effectively secure the high magnetic properties unique to the material of each magnetic steel plate 20a,..., 20h without giving any mechanical strain to 20h.

In practicing the present invention, the magnetic steel sheets 20a, 20a, and the like are not limited to the amorphous magnetic material, but may be, for example, a high silicon magnetic steel sheet material in which the magnetic material contains silicon at a content of about 6.5%. , 20h, the same effect as in the above embodiment can be achieved.

Further, in implementing the present invention, each magnetic steel sheet 20a,.
.., 20h, the arrangement position in relation to each of the high-tensile steel plates 10a,..., 10h may be appropriately changed as necessary.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG.
FIG. 3 is a perspective view of the laminated steel sheet in FIG. 3, FIG. 3 is a sectional view of the rotor main body in FIG. 1, and FIG. 4 is an exemplary perspective view of the magnetic steel sheet in FIG. Description of symbols R: rotor main body, S: rotary shaft, 10a, 10h
High-strength steel plate, 20a, ..., 20h ... magnetic steel plate, 30 ... conductor bar, 40, 50 ... short-circuit ring.

Continuation of front page (56) References JP-A-1-122333 (JP, A) JP-A-60-77267 (JP, U) JP-A-62-101349 (JP, U) JP-A-61-180562 (JP, U.S.A.) , U) (58) Fields surveyed (Int. Cl. ⁶ , DB name) H02K 17/16 H02K 1/00-1/16 H02K 1/18-1/26 H02K 1/28-1/34 H02K 15 / 00-15/02

Claims (1)

(57) [Claims] 1. A rotor for a cage-type induction motor comprising a rotor main body and a rotary shaft coaxially fitted into the rotor main body by press-fitting, wherein the rotor main body is made of an amorphous magnetic material or About 6.5 silicon
A plurality of disc-shaped magnetic steel sheets made of a high-strength magnetic material selected from high-silicon electromagnetic steel sheet materials containing a weight percent, and a high-tensile material that has a right-angle bending strength higher than that of the magnetic material and can be press-fitted to a rotating shaft. And a plurality of disc-shaped high-tensile steel sheets are coaxially co-laminated, and the high-tensile steel sheets are arranged on both ends of the coaxially co-mixed lamination, and short-circuit rings are arranged on both outer sides thereof. When the inner diameter of the magnetic steel sheet is a (μm), the outer diameter of the rotating shaft is b (μm), and the inner diameter of the high-strength steel sheet is c (μm), b + 10 (Μm) ≧
A rotor for a squirrel-cage induction motor, wherein the dimensions a, b, and c are defined so that the relationship a ≧ b−10 (μm)> c is satisfied.