JP2005278372A - Rotor for induction motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotor for an induction motor which efficiently disperses a centrifugal load generated at a secondary conductive portion of the rotor to a core of the rotor while restraining degradation in electrical characteristics and performance of the motor and an increase in material cost, and facilitates the realization of high-speed rotation driving. <P>SOLUTION: The rotor for the induction motor has: a rotor core 11 having a plurality of slots 12 made of electromagnetic steel material and partitioned around the axial core to be extended along the axial core; and the secondary conductive portion 14 formed by performing die-cast forming for a conductive material at the slots 12. The rotor is rotated by a relative effect between a rotary field generated at the surrounding and an induction current generated at the secondary conductive portion 14 by the rotary field, and provided with recess portions 12r at both the side surfaces of teeth 11T for partitioning the respective slots 12 respectively. The recess portions 12r are alternately disposed at the side surface of the teeth 11t facing each other. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  In the present invention, a plurality of slots extending along the axial center of the core made of a magnetic material are provided, and a conductive material is die-cast in these slots to form a secondary conductor portion. The present invention relates to a rotor of an induction motor that rotates by the interaction between a rotating magnetic field that is generated and an induced current that is generated in a secondary conductor by the rotating magnetic field.

  FIG. 6A is a schematic cross-sectional view illustrating the rotor of the induction motor. The rotor 30 has a plurality of slots 32 extending around the axis O of a core 31 made of a magnetic material (hereinafter referred to as “rotor core”) 31, and rotates the slots 32. This is called a closed slot which is spatially closed by a skin portion (hereinafter referred to as “bridge”) 31B on the outer peripheral portion of the child core 31, and a conductive material such as aluminum is poured into these slots 32 to obtain a secondary conductor portion 34. Is die-cast. In particular, in order to improve the motor characteristics, as shown in the sectional view of the main part in FIG. 6B, what is called an open slot in which a slit (space) 31s is provided in the bridge 31B is used.

The secondary conductor portion is provided with two slots in the upper and lower radial directions of the rotor core for the purpose of limiting the starting current or increasing the starting torque, and these slots are connected by elongated connecting slots to form double slots. There is a so-called double squirrel-cage conductor in which aluminum is poured into the double slot and a secondary conductor part composed of an upper part, a lower part and a bent part is die-cast (see, for example, Patent Document 1).
JP-A-7-163106

  On the other hand, with regard to special applications such as a drive source for automobiles, in recent years, there has been a demand for miniaturization and high output, and motors inevitably tend to require high-speed rotation.

  However, when an induction motor is used for high-speed rotation, there is hardly any sticking effect or adhesive effect by die casting between the slot and the secondary conductor, and the slot has a diameter of the rotor core. Since it has a shape that extends radially in the direction or a shape that extends in parallel, the centrifugal load of the secondary conductor portion caused by the rotating operation is concentrated on the bridge 11B, and particularly in the open slot shown in FIG. In the induction motor using the rotor, it is necessary to give the bridge 11B sufficient strength against the centrifugal load received from the secondary conductor 12.

  Therefore, measures against centrifugal loads include increasing the radial dimension (thickness) of the bridge 11B of the rotor core 11 or configuring the rotor core 11 with a high-strength material. In the case of countermeasures, inconveniences such as a decrease in motor characteristics accompanying an increase in the thickness of the bridge 11B and an increase in material cost due to the use of a high-strength material for the rotor core occur. In addition, induction motors used in general industrial applications are often operated at a rotational speed of about 1500 rpm to 3000 rpm, and the centrifugal load applied to the secondary conductor is sufficiently small, which may cause the above-described problems. There wasn't.

  On the other hand, as described above, the double squirrel-cage rotor is employed in a motor that requires a large torque at the time of start-up by commercial frequency drive for industrial use, and at the moment when the commercial frequency (for example, 50 Hz) is applied, The object is to efficiently convert the current concentrated in the vicinity of the outer surface of the upper portion of the secondary conductor portion into torque by the skin effect caused by the high frequency magnetic flux intersecting the secondary conductor portion in the vicinity of the rotor surface. . In the induction motor using this double squirrel-cage rotor, the range of the operating rotational speed is not high as in the case of general industrial induction motors, and it corresponds to a large centrifugal load generated in the secondary conductor. It was not structured.

  Further, in the case of the conventional double cage type rotor described above, the side wall of the connecting slot that connects the upper and lower slots protrudes into the slot as compared to the side wall of the upper and lower slots, so that a step formed between the upper and lower slots and the connecting slot. Although it is possible to receive the centrifugal load of the secondary conductor part at the part, since the cross-sectional area of the secondary conductor part is relatively reduced compared to the case of the rotor that is not a double cage type, the secondary resistance is increased. As a result, motor loss increases, efficiency decreases, and motor characteristics such as heat generation decrease. Further, when the induction motor is driven by an inverter, it can be driven at an optimum frequency for generating the maximum torque, and therefore it is not necessary to adopt a double squirrel-cage rotor.

  The problem to be solved by the present invention has been made in view of the above-mentioned facts, and from the secondary conductor portion of the rotor to the rotor core while suppressing a decrease in electric characteristics and performance of the motor and an increase in material cost. It is an object of the present invention to provide a rotor for an induction motor that can effectively disperse a centrifugal load applied to the motor and can easily realize a high-speed rotation operation.

  In the rotor of the induction motor according to the present invention, a plurality of slots extending along the axis of the core made of a magnetic material are provided, and a conductive material is die-cast into these slots to form a secondary conductor portion. The rotor of the induction motor thus configured is characterized in that recesses are provided on both side surfaces of the teeth partitioning each slot, and the recesses are alternately arranged on the side surfaces of the teeth facing each other.

  In this invention, the cross-sectional shape of the recessed part provided in the said tooth | gear can be made into the shape which consists of circular arc shape, a square shape, a triangle, or these combination. In the present invention, the teeth are provided on the other side surface opposite to the one side surface provided with the concave portion and provided with a convex portion at a position concentrically with the concave portion.

  According to the present invention, since the recesses are provided on both side surfaces of the teeth that partition the slots of the core made of the magnetic material, the protrusions that engage with the recesses are formed on the secondary conductor portion. The centrifugal load applied to the core from the secondary conductor portion can be effectively dispersed without changing the thickness of the bridge that causes an increase in material cost. Further, according to such a configuration, since there is no element that reduces the cross-sectional area of the secondary conductor portion, it is possible to prevent a decrease in electrical characteristics of the rotor and a local decrease in strength of the secondary conductor portion. Furthermore, according to the present invention, the concave portions provided in the teeth are alternately arranged on the side surfaces of the teeth facing each other, so that the concave portions are shifted from each other in the radial direction of the core. Even if the recess is provided, the magnetic flux path formed along the teeth is sufficiently secured.

  That is, according to the present invention, it is possible to effectively disperse the centrifugal load applied to the core from the secondary conductor of the rotor while suppressing the decrease in the electrical characteristics and performance of the rotor and the increase in the material cost. High-speed rotation operation can be easily realized.

  Further, in the present invention, if the cross-sectional shape of the recess provided in the teeth is an arc shape, since there is no edge in the recess, the distance between the recesses, that is, the tooth width is compared with the case where the edge exists. growing. For this reason, the depth (height) of the recess can be made larger than in the case of the recess having an edge, and a high centrifugal strength can be obtained, and the magnetic flux path of the teeth, that is, the electrical characteristics of the rotor can be improved. It can be secured easily.

  In the present invention, if the cross-sectional shape of the concave portion provided in the tooth is square, the strength of the convex portion on the secondary conductor side (the concave portion in the slot) in the centrifugal direction can be sufficiently secured, and the strength Since it is easy to secure, the depth (height) of the concave portion (the convex portion on the secondary conductor portion side) can be kept small. It is possible to minimize the decrease of the magnetic flux path in the rotor, that is, the deterioration of the electrical characteristics of the rotor.

  In the present invention, if the cross-sectional shape of the concave portion provided in the tooth is triangular, if the cross-sectional shape of the concave portion provided in the tooth is square, the portion of the convex portion on the secondary conductor side (the concave portion in the slot) is centrifuged. The strength in the direction can be sufficiently secured and the strength can be easily secured, so that the depth (height) of the concave portion (the convex portion on the secondary conductor side) can be kept small. The decrease in the magnetic flux path in the teeth, that is, the decrease in the electrical characteristics in the rotor due to the concave portions provided on both side surfaces of the teeth can be minimized.

  Further, in the present invention, if the teeth are on the other side opposite to the one side where the recess is provided and a convex part is provided at a position concentrically with the recess, the teeth in the direction around the axis of the tooth are provided. Since the width does not need to be reduced by the concave portions provided on both side surfaces, the influence on the magnetic flux path in the teeth, that is, the influence on the electrical characteristics of the rotor hardly occurs. The centrifugal load to be distributed can be effectively dispersed in the core.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view of an essential part of an embodiment of an induction motor (hereinafter referred to as “motor”) 100 that employs a rotor 10 according to the present invention.

  The motor 100 is a so-called three-phase AC motor, and has a shaft S rotatably supported by a bearing B in a case C, and is provided integrally with the shaft S on the same axis (axial center O). A squirrel-cage rotor 10 and stators 20 arranged at intervals of 180 ° around the axis O so as to surround the squirrel-cage rotor 10 are provided, and these stators 20 have a phase difference of 120 °. By supplying a phase alternating current, a rotating magnetic field can be generated around the rotor 10 in the case C.

  The squirrel-cage rotor 10 has a rotor core 11 formed by laminating a plurality of electromagnetic steel plates 11a along an axis O, and a short-circuit ring 13 disposed on the front and rear end faces of the rotor core 11 is provided with a plurality of secondary cores. The conductors 14 are connected.

  FIG. 2 is a front view of the electromagnetic steel sheet 11a forming the rotor core 11. As shown in FIG.

  The electromagnetic steel plate 11a has a disk shape having an opening H for fixing the shaft S and a plurality of slots 12 around its axis O. The electromagnetic steel plate 11a is formed along the shaft S as shown in FIG. By laminating a plurality, the rotor core 11 having a plurality of slots 12 which are partitioned around the axis O and extend along the axis O is formed. The slot 12 is a closed slot sealed inside by a bridge 11B.

  The secondary conductor portion 14 is connected to the short-circuit ring 13 by die-casting a conductive material such as aluminum in each of the slots 12 extending along the axis O after arranging the short-circuit ring 13 on the front and rear end faces of the rotor core 11. Do it. As a result, the cage rotor 10 has a mutual relationship between the rotating magnetic field B generated around the rotor 10 by the alternating current flowing through each stator 20 and the induced current I generated in the secondary conductor portion 14 by the rotating magnetic field B. The shaft S rotates around the axis O by the action.

  By the way, in this embodiment, as shown by the one-dot chain line in FIG. 2, the rotor core 11 is provided with recesses 12r on both side surfaces of the teeth 11T partitioning the slots 12, and the recesses 12r face each other. They are staggered on the sides. As a result, as shown in FIG. 3A, the secondary conductor portion 14 has a substantially trapezoidal external shape similar to that of the slot 14, and each contact surface with the teeth 11T is convex around the axis O. Since the convex portion 14p is formed, the concave portion 12r engaged with the convex portion 14p receives the centrifugal load of the secondary conductor portion 14.

  According to such a configuration, the concave portions 12r are provided on both side surfaces of the teeth 11T that partition the slots 12 of the rotor core 11, so that the convex portions 14p that engage with the concave portions 12r as shown in FIG. 3A. Is formed on each of the circumferential side surfaces of the secondary conductor portion 14, so that the rotor core can be removed from the secondary conductor portion 14 without changing the thickness L1 of the bridge 11B, which increases motor characteristics and material costs. The centrifugal load applied to 11 can be dispersed effectively. In addition, according to such a configuration, as shown in FIG. 3A, the convex portion 14p is formed on the side surface in the circumferential direction of the secondary conductor portion 14, thereby increasing the cross-sectional area as the secondary conductor portion 14. This is advantageous for the electrical characteristics of the rotor 10 because of the direction. Furthermore, according to such a configuration, the concave portions 12r provided in the teeth 11T are alternately arranged on the side surfaces of the teeth 11T facing each other, so that the concave portions 12r are displaced from each other in the radial direction R of the rotor core 11. Therefore, even if the recesses 12r are provided on both side surfaces of the tooth 11T, the magnetic flux path ΦL formed along the tooth 11T is sufficiently secured as shown by the broken line in FIG.

  That is, according to the present invention, the centrifugal load applied to the bridge 11B from the secondary conductor 14 of the rotor 10 is effectively dispersed while suppressing the deterioration of the electrical characteristics and performance of the rotor 10 and the increase in material cost. And high-speed rotation operation can be easily realized.

  Further, in the present invention, if the cross-sectional shape of the recess 12r provided in the tooth 11T is an arc, there is no edge in the recess 12r. Therefore, the distance of the recess 12r, that is, the width of the tooth 11T (the teeth 11T The radial width L2 at the axis O is larger than when there is an edge. For this reason, the depth (height) of the recess 12r can be made larger than in the case of the recess having an edge, and a high centrifugal strength can be obtained, and the magnetic flux path Φ of the teeth 11T, that is, the rotor 10 Electrical characteristics can be easily secured. Note that the number of recesses 12r is not limited to one, and a plurality of recesses 12r can be provided, and FIG. 3B shows an example thereof. However, in this case, it is not necessary to have the same number of the recesses 12r on the side surfaces of the teeth 11T facing each other with the recesses 12r provided in each tooth 11T.

  The dimension range of the recesses provided in the teeth 11T can be changed in various ways. In particular, the centrifugal load received by the bridge 11B of the rotor core 11, that is, the range of motor rotation speed during operation (high rotation speed). The sectional shape of the recess can also be changed according to the motor size (the outer dimension of the rotor 10 and the radial dimension of the rotor of the slot 12). For example, each side surface of the tooth 11T has a square section. A recess 12s having a shape may be provided. FIG. 4A is an example thereof, and the recess 12s has a rectangular cross-sectional shape extending in the radial direction. According to such a configuration, the strength of the convex portion 14p of the secondary conductor portion 14 (the concave portion 12s in the slot 12) in the centrifugal direction can be sufficiently secured, and the strength can be easily secured. Since the depth (height) of the convex portion 14p) can be kept small, the magnetic flux path ΦL in the tooth 11T is reduced by providing the concave portions 12s on both side surfaces of the tooth 11T, that is, the electricity in the rotor 10 The degradation of the mechanical characteristics can be minimized. The number of recesses 12s is not limited to one, and a plurality of recesses 12s can be provided, and an example is shown in FIG.

  When a plurality of recesses are provided, as shown in FIG. 5A, it is also possible to combine an arc-shaped recess 12r and a square recess 12s. According to such a configuration, the arcuate recess 12r with a small amount of biting into the tooth 11T and the square recess 12s with emphasis on the strength of the secondary conductor 14 are provided side by side, whereby the width L3 (see FIG. This is effective when there is a restriction on the arrangement of the recesses, for example, when it is not possible to ensure sufficient.

Further, concave portions 12t each having a triangular cross-sectional shape may be provided on both side surfaces of the teeth 11T. FIG. 5B is an example thereof, and the recess 12t includes a slope 12t _{1 that} is inclined toward the bridge 11B that receives a centrifugal load, and a vertical surface 12t ₂ that receives the centrifugal load. According to such a configuration, the strength of the convex portion 14p (the concave portion 12t in the slot 12) of the secondary conductor portion 14 in the centrifugal direction can be sufficiently secured, and the strength can be easily secured. Since the depth (height) of the convex portion 14p) can be kept small, the magnetic flux path ΦL in the tooth 11T is reduced by providing the concave portions 12t on both side surfaces of the tooth 11T, that is, the electricity in the rotor 10 The degradation of the mechanical characteristics can be minimized. The number of the recesses 12t is not limited to one, and a plurality of recesses can be provided. When a plurality of recesses are provided, the arc-shaped recess 12r and the square recess 12s can be combined.

  In the present invention, as illustrated in FIGS. 5C and 5D, the teeth 11T are on the other side opposite to the one side where the recesses 12r and 12s (12t) are provided, and the recesses 12r, Convex portions 12p having the same cross-sectional shape as the concave portions 12r and 12s (12t) may be provided at positions concentrically with 12s (12t) (see the dashed line in the figure). According to such a configuration, the width in the direction around the axis O of the tooth 11T does not need to be reduced by the recesses 12r and 12s (12t) provided on both side surfaces thereof, and therefore the influence on the magnetic flux path ΦL in the tooth 11T. That is, the centrifugal load generated in the secondary conductor portion 14 can be effectively dispersed in the rotor core 11 with almost no influence on the electrical characteristics of the rotor 10.

  Each form mentioned above can add various change. For example, although the present embodiment has been described with a closed slot rotor, the present invention is more effective when used in an open slot rotor or the like in which the strength of the bridge 11B is difficult to ensure.

It is one form of the induction motor which employ | adopts the rotor which concerns on this invention, Comprising: It is principal part sectional drawing which shows the side. It is a front view of the electromagnetic steel plate which forms the rotor core of the rotor in the same form. (a), (b) is principal part sectional drawing which shows the rotor of the same form, respectively, and principal part sectional drawing which shows the rotor which is a modification of the same form. (a), (b) is principal part sectional drawing which shows the rotor which is the other form of this invention, respectively, and principal part sectional drawing which shows the rotor which is a modification of the form. (a) is principal part sectional drawing which shows the modification of the rotor which combined FIG. 3, FIG. 4, (b), (c) is a principal part which shows the rotor which is another form of this invention, respectively. It is principal part sectional drawing which shows the rotor which is a fragmentary sectional view and the modification of the form, (d) is principal part sectional drawing which shows the rotor which is further another form of this invention. (a), (b) is the schematic cross section which illustrates the rotor of the conventional induction motor, respectively, and the principal part cross section of another rotor.

Explanation of symbols

10 rotor
11 Rotor core (core)
11B bridge
11T Teeth
12 slots
12r Arc-shaped recess
12s square recess
12t triangular recess
13 Short circuit ring
14 Secondary conductor

Claims (5)

In the rotor of the induction motor in which a plurality of slots extending along the axial center of the core made of a magnetic material are provided, and a secondary conductor is formed by die-casting a conductive material in these slots.
A rotor for an induction motor, wherein recesses are provided on both side surfaces of teeth separating each slot, and the recesses are alternately arranged on side surfaces of the teeth facing each other.   The rotor of the induction motor according to claim 1, wherein a cross-sectional shape of the concave portion is an arc shape.   The induction motor rotor according to claim 1 or 2, wherein the recess has a square cross-sectional shape.   The rotor of the induction motor according to any one of claims 1 to 3, wherein a cross-sectional shape of the concave portion is a triangle.   5. The induction motor according to claim 1, wherein the teeth are provided on the other side opposite to the side surface on which the concave portion is provided and are provided with a convex portion at a position concentrically with the concave portion. Rotor.

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