Squirrel cage rotor and induction motor

Abstract

To improve a support structure of an end ring of an induction motor.SOLUTION: A squirrel cage rotor has a rotor core, a shaft extending along a rotation axis of the rotor core and penetrating a center of the rotor core in an axial direction, a plurality of rotor bars penetrating the rotor core in the axial direction, an end ring arranged on one side of the axial direction of the rotor core and electrically connecting the plurality of rotor bars, a first support member arranged on one side of the axial direction of the end ring and supporting the end ring, and a second support member arranged on the other side of the axial direction of the end ring and supporting the end ring. The first support member and the second support member support so as to regulate a movement to the outside in a radial direction of the end ring.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a squirrel cage rotor and an induction motor. [Background technology]

[0002] Conventionally, induction motor rotors have used squirrel cage rotors formed by assembling squirrel cage conductors to a rotor core made of laminated steel plates. The squirrel cage conductors include a number of rotor bars that are inserted into slots in the rotor core and extend in the axial direction, and a pair of end rings that are disposed on both ends of the rotor core and electrically connect the ends of the rotor bars.

[0003] For example, when the induction motor is applied to an electric vehicle or the like, there is a strong demand for increasing the rotation speed of the induction motor to achieve higher output. However, the end rings may be damaged or deformed due to centrifugal force, particularly during high-speed rotation.

[0004] Patent Document 1 proposes a configuration in which a reinforcing ring is provided that fits onto the outer diameter portion of the end ring and the outer diameter portion of the rotating shaft, thereby suppressing deformation of the end ring. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2007-202235 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, the structure disclosed in Patent Document 1 has a problem in that stress concentration may occur at the contact portion between the reinforcing ring and the end ring. If stress concentration occurs, the reinforcing ring or the end ring may be damaged. In addition, no consideration was given to axial runout of the end ring.

[0007] For this reason, there has been room for improvement in the support structure for the end rings of conventional induction motors.

[0008] The present invention aims to improve the support structure of the end rings of an induction motor. [Means for solving the problem]

[0009] A squirrel-cage rotor according to one embodiment of the present invention comprises a rotor core, a shaft extending along the rotation axis of the rotor core and axially penetrating the center of the rotor core, a plurality of rotor bars axially penetrating the rotor core, an end ring arranged on one axial side of the rotor core and electrically connecting the plurality of rotor bars, a first support member arranged on one axial side of the end ring and supporting the end ring, and a second support member arranged on the other axial side of the end ring and supporting the end ring, wherein the first support member and the second support member support the end ring so as to restrict radial outward movement of the end ring.

[0010] In the squirrel cage rotor according to the above aspect, the first support member and the second support member support the end rings radially inwardly of the radially outer ends of the end rings.

[0011] In the squirrel cage rotor according to the above aspect, the first support member and the second support member support the end ring in an L-shape.

[0012] In the squirrel-cage rotor according to the above aspect, the first support member and the second support member support the end rings so as to restrict movement of the end rings in the axial direction.

[0013] An induction motor according to one aspect of the present invention includes the above-described squirrel cage rotor and a stator. Effect of the Invention

[0014] According to one aspect of the present invention, the support structure of the end rings of an induction motor can be improved. [Brief description of the drawings]

[0015] [Figure 1] 1 is a perspective view showing one axial side of a rotor according to a first embodiment of the present invention. [Diagram 2] 2 is a perspective view showing a rotor core and a second support member in the rotor shown in FIG. 1. [Diagram 3] 1 is a side cross-sectional view of a rotor according to a first embodiment of the present invention. [Figure 4] FIG. 11 is a side cross-sectional view of a rotor according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the embodiment, in order to make the description easier to understand, structures and elements other than the main parts of the present invention will be described in a simplified or omitted manner. In addition, in the drawings, the same elements are given the same reference numerals. Note that the shapes, dimensions, etc. of each element shown in the drawings are shown diagrammatically and do not represent the actual shapes, dimensions, etc.

[0017] In the drawings, the rotating shaft of the induction motor, i.e., the rotating shaft of the rotor core, is indicated by the symbol AX as necessary. In the following description, the direction parallel to the rotating shaft AX is referred to as the axial direction, the circumferential direction centered on the rotating shaft AX is simply referred to as the circumferential direction, and the radial direction centered on the rotating shaft AX is simply referred to as the radial direction. In the axial direction, the side indicated by the arrow on the rotating shaft AX is referred to as the one axial side, and the opposite side is referred to as the other axial side. In the radial direction, the side closer to the rotating shaft AX is referred to as the radial inner side, and the side farther from the rotating shaft AX is referred to as the radial outer side.

[0018] First Embodiment FIG. 1 is a perspective view showing one axial side of a rotor according to a first embodiment of the present invention. The rotor 100 has a rotor core 110, a rotor bar 121 (see FIG. 3), an end ring 122, a first support member 170, and a second support member 150. The rotor 100 is an example of a squirrel-cage rotor. The rotor 100 constitutes a motor. This motor is an example of an induction motor. This motor has the rotor 100, a shaft 130 (see FIG. 3) that is a rotating shaft fixed to the rotor 100, and a stator disposed radially outside the rotor 100 with a gap therebetween. This stator is an example of a stator of an induction motor. The first support member 170 and the second support member 150 support the end ring 122.

[0019] The other axial side of the rotor 100 has the same configuration as the one axial side of the rotor 100, and therefore description thereof will be omitted. The present invention is not limited to both the one axial side and the other axial side of the rotor 100 having the same configuration, and only one side may have the configuration shown in FIG.

[0020] The rotor core 110 is formed by laminating a plurality of electromagnetic steel plates, such as disk-shaped silicon steel plates, in the axial direction. The rotor core 110 is formed into a cylindrical shape by laminating the electromagnetic steel plates. The rotor core 110 is an example of a rotor core. The shaft 130 extends along the rotation axis AX and passes through the center of the rotor core 110 in the axial direction. The shaft 130 is fixed to the rotor core 110 by shrink fitting or the like. The motor case that houses the stator and the rotor core 110 has bearings fixed to one axial side and the other axial side of the rotor core 110. The shaft 130 is rotatably supported by this pair of bearings.

[0021] Fig. 2 is a perspective view showing the rotor core 110 and the second support member 150 of the rotor 100 shown in Fig. 1. Fig. 2 shows a state in which the first support member 170 and the end ring 122 have been removed from the rotor 100 in Fig. 1.

[0022] The rotor core 110 has slots 110a which are through holes penetrating in the axial direction. The rotor core 110 has a plurality of slots 110a arranged at equal intervals in the circumferential direction. A rotor bar 121 which penetrates the rotor core 110 and extends in the axial direction is inserted into each of the plurality of slots 110a. The rotor bar 121 is made of a conductive metal such as aluminum or copper, and passes an induced current (secondary current) due to a rotating magnetic field. The cross-sectional shape of the rotor bar 121 may be circular or rectangular. In this embodiment, the cross-sectional shapes of the slots 110a and the rotor bar 121 are elliptical. The slots 110a and the rotor bar 121 may be arranged in a skew shape, inclined obliquely with respect to the axial direction.

[0023] The end rings 122 are made of a conductive metal such as aluminum, and are arranged in pairs at both axial ends of the rotor core 110. The end rings 122 are annular members that face at least the slots 110a of the rotor core 110 in the axial direction and are arranged radially outward of the shaft 130. The end rings 122 are joined to the axial ends of each of the multiple rotor bars 121 by, for example, brazing or welding. Each of the pair of end rings 122 electrically connects the multiple rotor bars 121 that are arranged in a ring shape around the rotor core 110. By joining the rotor bars 121 and the end rings 122, a so-called cage conductor is formed in the rotor 100.

[0024] The end rings 122 and the rotor bars 121 may be joined by other methods. For example, after the rotor bars 121 are inserted into the slots 110a of the rotor core 110, a die, for example, is attached to the end of the rotor core 110 to form the end rings 122. Then, the material of the end rings 122 (for example, aluminum) is cast into the die to produce the end rings 122 joined to the rotor bars 121. The die is removed after the end rings 122 are produced.

[0025] Fig. 3 is a side cross-sectional view of the rotor according to the first embodiment of the present invention. Fig. 3 is a cross-sectional view taken along a plane passing through the rotation axis AX and parallel to the rotation axis AX. Fig. 3 shows one axial side of the rotor 100, and the upper half of the rotation axis AX.

[0026] The end ring 122 is disposed on one axial side of the rotor core 110. The second support member 150 is disposed on the other axial side of the end ring 122. The second support member 150 is an annular member disposed on the radially outer side of the shaft 130. The second support member 150 is formed of a metal material having higher rigidity than the end ring 122, such as stainless steel or titanium. The first support member 170 is disposed on one axial side of the end ring 122. The first support member 170 is an annular member disposed on the radially outer side of the shaft 130. The first support member 170 is formed of a metal material having higher rigidity than the end ring 122, such as stainless steel or titanium.

[0027] The end ring 122 is joined to the rotor bar 121 on the radially outer side. The end ring 122 has a protruding portion 122a on the radially inner side that protrudes from the surface on the other axial side to the other axial side. The protruding portion 122a protrudes to the other axial side over the entire circumferential circumference. The protruding portion 122a protrudes to the other axial side radially inward from the radially outer end of the end ring 122. The end ring 122 has a protruding portion 122b on the radially inner side that protrudes to the one axial side from the surface on one axial side. The protruding portion 122b protrudes to the one axial side over the entire circumferential circumference. The protruding portion 122b protrudes to the one axial side radially inward from the radially inner end of the rotor bar 121. The radially outer surface of the protruding portion 122a is located radially inner than the radially outer surface of the protruding portion 122b.

[0028] The first support member 170 has a base 170a having a surface perpendicular to the axial direction, and a protruding portion 170b protruding from the surface of the base 170a on the other axial side radially outside the base 170a to the other axial direction side. The base 170a has a ring-like shape when viewed from the axial direction, and has a through-hole at its center through which the shaft 130 passes. The protruding portion 170b protrudes in the other axial direction around the entire circumferential circumference of the base 170a. The first support member 170 is manufactured by, for example, injection molding.

[0029] The first support member 170 may be fixed to the shaft 130 by, for example, shrink fitting or screwing. The surface on the other axial direction side of the protruding portion 170b of the first support member 170 is located on the other axial direction side of the surface on one axial direction side of the protruding portion 122b of the end ring 122. The radially inner surface of the protruding portion 170b of the first support member 170 contacts the radially outer surface of the protruding portion 122b of the end ring 122. The first support member 170 may be fixed to the end ring 122 by, for example, shrink fitting or screwing.

[0030] At least one of the other axial surface of the protruding portion 170b of the first support member 170 and the other axial surface of the base portion 170a contacts the end ring 122.

[0031] The second support member 150 has a base 150a having a surface perpendicular to the axial direction, and a protruding portion 150b protruding from a surface on one axial side of the base 150a on the radially outer side of the base 150a in the axial direction. The base 150a has a ring-like shape when viewed from the axial direction, and has a through-hole at its center through which the shaft 130 passes. The protruding portion 150b protrudes in the axial direction on one side around the entire circumferential circumference of the base 150a. The second support member 150 is produced by, for example, injection molding.

[0032] The second support member 150 may be fixed to the shaft 130 by, for example, shrink fitting or screwing. A surface on one axial side of the protruding portion 150b of the second support member 150 is located on one axial side of a surface on the other axial side of the protruding portion 122a of the end ring 122. A radially inner surface of the protruding portion 150b of the second support member 150 contacts a radially outer surface of the protruding portion 122a of the end ring 122. The second support member 150 may be fixed to the end ring 122 by, for example, shrink fitting or screwing.

[0033] The other axial surface of the base portion 150a of the second support member 150 contacts the one axial surface of the rotor core 110. At least one of the one axial surface of the protruding portion 150b of the second support member 150 and the one axial surface of the base portion 150a contacts the end ring 122.

[0034] According to this embodiment, by arranging a first support member 170 on one axial side of the end ring 122 and arranging a second support member 150 on the other axial side of the end ring 122, axial vibration of the end ring 122 can be suppressed.

[0035] According to this embodiment, an L-shaped support structure is used in which the protrusions 122a and 122b of the end ring 122 are supported by the L-shaped first support member 170 and second support member 150. Therefore, when the centrifugal force generated by the rotation of the motor is applied to the end ring 122, the second support member 150 and the first support member 170 are located on the shortest path along which the force acts.

[0036] According to this embodiment, it is possible to minimize the radially outward stretch of the end rings 122 by utilizing the mechanical characteristics (rigidity) of the first support member 170 and the second support member 150. Furthermore, according to this embodiment, by holding the end rings 122 with the first support member 170 and the second support member 150 on the radially inner side of the rotor core 110, it is possible to eliminate the points where stress was concentrated in the past, suppress the runout of the end rings 122 in the radial and axial directions, and alleviate the stress concentration occurring in the end rings 122 near the rotor core 122.

[0037] <Second embodiment> Next, a second embodiment of the present invention will be described. FIG. 4 is a side cross-sectional view of a rotor according to a second embodiment of the present invention. FIG. 4 is a cross-sectional view showing a section cut along a plane passing through the rotation axis AX and parallel to the rotation axis AX, as in FIG. 3. FIG. 4 shows one axial side of the rotor 100 and the upper half of the rotation axis AX, as in FIG. 3. The second embodiment differs from the first embodiment in that it has a shaft 230 instead of the shaft 130 of the first embodiment, and has a first support member 270 instead of the first support member 170 of the first embodiment. The same reference numerals as those in FIG. 1 and FIG. 2 are used for the same configurations as in the first embodiment, and detailed description thereof will be omitted.

[0038] The shaft 230 of the second embodiment has a cylindrical base portion 230a extending in the axial direction, and a protruding portion 230b protruding radially outward from a radially outer surface on one axial side of the base portion 230a. The protruding portion 230b protrudes radially outward over the entire circumferential circumference.

[0039] The first support member 270 of the second embodiment is disposed on one axial side of the end ring 122. The first support member 270 is an annular member disposed radially outside the shaft 230. The first support member 270 is formed of a metal material having higher rigidity than the end ring 122, such as stainless steel or titanium.

[0040] The first support member 270 has a base 270a having a surface perpendicular to the axial direction, a protruding portion 270b protruding from the surface of the base 270a on the other axial side on the radial outer side of the base 270a to the other axial direction, and a protruding portion 270c protruding from the surface of the base 270a on the one axial side on the radial inner side of the base 270a to one axial direction. The base 270a has a ring-like shape when viewed from the axial direction, and has a through hole in the center through which the shaft 230 passes. The protruding portion 270b protrudes in the other axial direction around the entire circumferential circumference of the base 270a. The protruding portion 270c protrudes in the one axial direction around the entire circumferential circumference of the base 270a. The first support member 270 is manufactured by, for example, injection molding.

[0041] The first support member 270 may be fixed to the shaft 230 by, for example, shrink fitting or screwing. The surface on the other axial direction side of the protruding portion 270b of the first support member 270 is located on the other axial direction side of the surface on one axial direction side of the protruding portion 122b of the end ring 122. The radially inner surface of the protruding portion 270b of the first support member 270 contacts the radially outer surface of the protruding portion 122b of the end ring 122. The radially inner surface of the protruding portion 270c of the first support member 270 contacts the radially outer surface of the base portion 230a of the shaft 230. The first support member 270 may be fixed to the end ring 122 by, for example, shrink fitting or screwing.

[0042] At least one of the other axial surface of the protruding portion 270b of the first support member 270 and the other axial surface of the base portion 270a contacts the end ring 122.

[0043] A radially outer surface of the protruding portion 230b of the shaft 230 contacts a radially inner surface of the protruding portion 122b of the end ring 122. A surface on one axial side of the protruding portion 230b of the shaft 230 contacts a surface on the other axial side of the base portion 270a of the first support member 270.

[0044] According to this embodiment, the first support member 270 is structured to contact the protruding portion 230b of the shaft 230, so that the first support member 270 can be positioned with respect to the shaft 230. In addition, the movement of the first support member 270 is restricted by the protruding portion 230b, so that the stress concentration on the end ring 122 can be further alleviated.

[0045] The present invention is not limited to the above-mentioned embodiment, and various improvements and design changes may be made without departing from the spirit of the present invention. In addition, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0046] 100... rotor, 110... rotor core, 122... end ring, 150... second support member, 170... first support member

Claims

1. A rotor core; a shaft extending along a rotation axis of the rotor core and passing through a center of the rotor core in an axial direction; A plurality of rotor bars axially penetrating the rotor core; an end ring disposed on one axial side of the rotor core and electrically connecting the rotor bars; a first support member that is disposed on one axial side of the end ring and supports the end ring; a second support member that is disposed on the other axial side of the end ring and supports the end ring; having The first support member and the second support member support the end ring so as to restrict the end ring from moving radially outward. A cage rotor characterized by:

2. The first support member and the second support member support the end ring radially inward from a radially outer end of the end ring.

2. A squirrel cage rotor according to claim 1.

3. The first support member and the second support member support the end ring in an L-shape.

2. A squirrel cage rotor according to claim 1.

4. The first support member and the second support member support the end ring so as to restrict the end ring from moving in the axial direction.

2. A squirrel cage rotor according to claim 1.

5. A squirrel cage rotor according to claim 1; A stator and An induction motor characterized by:

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