JP2013074694A - Permanent magnet buried electric motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a permanent magnet buried electric motor in which magnetic flux leakage and stress concentration on a steel plate constituting a rotor core can be suppressed.SOLUTION: A cavity 22 formed between a support Y and a permanent magnet is configured to connect edges 22A, 22B in a curved surface shape by an edge 22C parallel to an axis D. Therefore, an area of the cavity 22 can be formed widest and a magnetic flux leakage suppressing function can be improved. On the other hand, stress for the load caused by a centrifugal force in a core area X is generated in the support Y during rotation of a rotor. By forming the edges 22A and 22B of the cavity 22 in the curved surface shape, however, the risk of concentrating the stress to a specific spot is eliminated and there is an advantage that strength design of the support Y is facilitated. In particular, by forming the edge 22C parallel to the axis D in the cavity 22, the edges 22A, 22B can be formed into curved surface having a large curvature radius, thereby more improving stress dispersion effects.

Description

  The present invention relates to a permanent magnet embedded electric motor in which a permanent magnet is embedded in a rotor.

  Patent Document 1 discloses an invention that aims to provide a permanent magnet embedded rotary electric machine that can improve magnetic characteristics while ensuring strength. In the rotor disclosed in Patent Literature 1, two permanent magnets arranged so as to spread toward the outside of the rotor are used as one pole, and a plurality of poles are embedded inside the rotor. Moreover, the rotor which embeds a permanent magnet is the structure which laminated | stacked two types of 1st and 2nd laminated steel plates with different structures alternately.

  That is, the first laminated steel sheet includes two first holding holes for holding two permanent magnets, two first cavities disposed between the two first holding holes, two permanent magnets, and A plurality of poles are formed with two second cavities arranged between two other adjacent permanent magnets as one pole. The second laminated steel plate includes two second holding hole portions for holding two permanent magnets, two third cavity portions arranged between the two second holding hole portions, and a second of the first laminated steel plate. A plurality of poles are formed with two notches that are arranged so as to overlap the cavity and communicate with the outer edge of the rotor as one pole. The iron core of the rotor is configured by alternately laminating a first laminated steel plate and a second laminated steel plate. Moreover, the magnetic flux short circuit in an outer edge part is reduced by presence of a 2nd laminated steel plate.

JP 2011-4480 A

  In the configuration of the second laminated steel sheet, the iron core portion surrounded by the two permanent magnets and the outer edge of the rotor is located between the two permanent magnets described as the central support portion due to the presence of the two notches. Supported by the core part. Therefore, the central support portion has a problem that stress concentration due to a load caused by the centrifugal force of the rotor occurs, and the central support portion is easily damaged. For this reason, it is necessary to increase the area of the central support portion and increase the strength, but conversely, if the central support portion is widened, there is a problem that magnetic flux leakage is likely to occur.

  The present invention provides a permanent magnet embedded electric motor that can suppress magnetic flux leakage and stress concentration in a steel plate constituting a rotor core.

  The first aspect includes a rotor having a rotating shaft and a stator having a coil, and the rotor is constituted by a rotor core formed by laminating a plurality of steel plates in the axial direction of the rotating shaft and a permanent magnet embedded in the rotor core. In the permanent magnet-embedded electric motor, at least one of the steel plates has a plurality of pairs of magnet insertion holes drilled so as to spread toward the outer edge, and at the end of the magnet insertion hole on the q-axis side. Is connected to a notch that opens to the outer edge, a gap exists at the d-axis side end of the magnet insertion hole, and a pair of the magnet insertion hole and the notch are provided on the outer edge of the steel plate. Is formed between the pair of gaps, and a support part for supporting the core area is formed between the pair of gaps, and the edges at both ends in the d-axis direction of the gaps are curved away from the d-axis. It is specially formed To.

  According to the first aspect of the present invention, the gap is formed between the pair of permanent magnets and the support portion, thereby suppressing the leakage of magnetic flux, and the both ends of the support portion sandwiched between the gap portions are curved. Made it possible to suppress concentration.

  A second aspect of the present invention is characterized in that the edge of the gap portion other than both ends in the d-axis direction is configured by a straight line parallel to the d-axis. According to the second aspect, the gap region can be formed most widely while maintaining the necessary width in terms of the strength of the support portion, and the leakage magnetic flux can be reduced more effectively.

  According to a third aspect of the present invention, in the state where the permanent magnet is inserted into the magnet insertion hole, the d-axis side end portion of the permanent magnet is chamfered. According to the third aspect, since the end of the permanent magnet can be inserted into the gap, the width of the magnet can be substantially increased. For this reason, motor efficiency can be raised without enlarging a rotor core, and the operating efficiency of an electric motor can be raised.

  A fourth aspect of the present invention is characterized in that the notch is bent and extended from the magnet insertion hole to the d-axis side and opens at an outer edge of the steel plate. According to claim 4, the area of the core region can be made as small as possible. For this reason, the centrifugal force of a core area | region can be made small and the stress concerning a support part can be made smaller.

  The present invention can suppress magnetic flux leakage in the rotor core and suppress stress concentration that occurs during rotation of the rotor.

It is a side view of the rotor and stator of the electric motor which shows 1st Embodiment. It is a side view which shows the steel plate which makes a rotor core. It is the elements on larger scale of the steel plate which makes a rotor core. It is the elements on larger scale of the steel plate which embed | buried the permanent magnet. It is the elements on larger scale of the steel plate which embed | buried the permanent magnet which shows 2nd Embodiment. It is the elements on larger scale of the steel plate which embed | buried the permanent magnet which shows 3rd Embodiment.

(First embodiment)
1st Embodiment shows the example which implemented this invention to the permanent-magnet embedded electric motor mounted in a vehicle, and demonstrates based on FIGS. 1-4. In FIG. 1, a permanent magnet embedded electric motor 1 includes a rotor 2 and a stator 3 disposed on the outer periphery of the rotor 2. The rotor core 4 constituting the rotor 2 is configured by laminating a plurality of steel plates made of a magnetic material. A rotating shaft (not shown) is inserted into the rotating shaft hole 5 formed at the center of the rotor core 4 and fixed by press fitting or appropriate means such as an adhesive or a key. The d-axis shown in FIGS. 1 to 4 is a virtual axis that passes through the center between a pair of permanent magnets 30 described later (the same applies to other pairs of permanent magnets) and intersects the center of the rotary shaft hole 5. . The q-axis is a virtual axis that passes through the center between permanent magnets 30 having different magnetic poles, which will be described later, and intersects the center of the rotation shaft hole 5. The d-axis and the q-axis are widely used in the performance evaluation of permanent magnet embedded electric motors. The stator 3 is wound with a coil 3A.

  In the steel plate forming the rotor core 4, as shown in FIG. 2, a pair of two magnet insertion holes 6 are arranged so as to be symmetrical with respect to the d axis, and spread in a V shape toward the outer edge 4A of the steel plate. So that it is drilled. Eight pairs of magnet insertion holes 6 to 13 are formed in the entire area of the rotor core 4 so as to be evenly arranged. At the end on the q-axis side, the pair of magnet insertion holes 6 are extended so as to be bent at a predetermined angle, and are connected to form a pair of two notches 14 opened at the outer edge 4A. . Similarly, a pair of notch portions 15 to 21 having the same shape as the notch portion 14 are connected to the other seven pairs of magnet insertion holes 7 to 13, respectively.

  The pair of magnet insertion holes 6 are formed with a pair of two gaps 22 formed on the opposite side (d-axis side end) from the notch 14. Similarly, a pair of gap portions 23 to 29 having the same shape as the gap portion 22 are connected to the other seven pairs of magnet insertion holes 7 to 13, respectively. The gap 22 is formed on the edge 22A connected to the edge 6A of the magnet insertion hole 6 located on the outer edge 4A side (outside in the d axis) of the rotor core 4 and on the rotating shaft hole 5 side (inside in the d axis) of the rotor core 4. An edge portion 22B connected to the edge portion 6B is provided, and the edge portions 22A and 22B at both ends in the d-axis direction are formed in a curved shape so as to be separated from the d-axis. Further, the edges 22A and 22B other than both ends in the d-axis direction are connected by an edge 22C formed by a straight line parallel to the d-axis. The formation of the edge 22C parallel to the d-axis allows the widest region in which the gap 22 is formed while ensuring the minimum strength compared to the case where the edge 22C is not parallel to the d-axis. It is.

  On the outer edge 4 </ b> A side of the steel plate, a core region X is formed which is divided by the formation of the pair of notch portions 14 and is surrounded by the pair of magnet insertion holes 6, and between the pair of gap portions 22, that is, the pair of gap portions 22. A support portion Y having a width L1 is formed between the respective edge portions 22C. The support portion Y supports the core region X, and becomes a position where all the loads associated with the centrifugal force of the core region X are applied when the rotor 2 rotates. For this reason, the width L <b> 1 of the support portion Y is set to a size that can handle the load caused by the centrifugal force of the core region X. In addition, the core area | region X and the support part Y are similarly formed also in the magnet insertion holes 7-13 which make each other pair, the notch parts 15-21, and the space | gap parts 23-29.

  As shown in FIG. 4, in each pair of magnet insertion holes 6 to 13, a flat permanent magnet 30 made of a rare earth magnet such as a neodymium magnet is embedded. The pair of two permanent magnets 30 embedded in the pair of magnet insertion holes 6 constitute one pole, and the rotor core 4 has eight pairs of permanent magnets 30 embedded therein to form eight poles. The permanent magnet 30 is not limited to a rare earth magnet, and other magnets such as an alloy magnet and a ferrite magnet can be used. Further, the magnet insertion holes 6 to 13 described in the specification and claims of the present application are a space portion having a width corresponding to the width L2 of the contact area between the permanent magnet 30 and the steel plate when the permanent magnet 30 is embedded. Shall point to. In this case, the width L2 refers to a direction extending in a V shape toward the outer edge 4A of the steel plate.

  The configuration in which the pair of magnet insertion holes 6 are extended to form the pair of notches 14 is formed between the pair of permanent magnets 30 and the adjacent permanent magnets 30 having different magnetic poles (q-axis) on the outer edge 4A side of the steel plate. ) Has an advantage of suppressing magnetic flux leakage. As shown in FIG. 3, the configuration in which the pair of notches 14 bend from the pair of magnet insertion holes 6 and open to the outer edge 4 </ b> A of the rotor core 4 has the pair of notches 14 as the pair of magnet insertion holes 6. The area of the core region X can be made as small as possible as compared with the configuration formed on the linear extension line. For this reason, it is possible to reduce the centrifugal force of the core region X and to further reduce the stress applied to the support portion Y.

  When the region of the support portion Y becomes large, a short circuit of the magnetic flux via the support portion Y is likely to occur between the pair of permanent magnets 30 and the magnetic flux leakage increases. However, since the gap portions 22 to 29 formed between the support portion Y and the permanent magnet 30 are configured to connect the curved edge portions 22A and 22B by the edge portion 22C parallel to the d axis, the gap portions 22 to Each region of 29 can be formed most widely, and the function of suppressing magnetic flux leakage can be further enhanced. Therefore, suppression of magnetic flux leakage increases motor efficiency and enables efficient operation of the permanent magnet embedded electric motor 1.

  On the other hand, during the rotation of the rotor 2, stress due to a load accompanying the centrifugal force of the core region X is generated in the support portion Y. However, this stress is such that each edge 22A and each edge 22B of the gaps 22 to 29 are both curved, so there is no risk of stress concentration at a specific location, and the support portion Y breaks. There is an advantage that the risk of motor failure is reduced.

  The present invention is not limited to the configuration of each of the embodiments described above, and various modifications are possible within the scope of the gist of the present invention, and can be implemented as follows.

(1) The gaps 22 to 29 in the first embodiment can be changed to the second embodiment shown in FIG. In the second embodiment, the gaps 42 to 49 (only a part of the pair of gaps 42 and the pair of gaps 43 and 49 are shown in FIG. 5) have a width L1 of the support Y. The curved surface connected to the edge 50 parallel to the d-axis and the edge located on the outer edge 4A side (outside in the d-axis) and the rotating shaft hole 5 side (inside in the d-axis) of the steel plate in the magnet insertion holes 6-13. Edge portions 51 and 52. The curved edge 52 on the rotating shaft hole 5 side is formed so as to swell in the width direction of the magnet insertion holes 6 to 13 as in the first embodiment, but is curved on the outer edge 4A side. The edge portion 51 is formed so as to swell in the thickness direction of the magnet insertion holes 6 to 13. The curved edge portions 51 and 52 may be formed in a direction opposite to the example of FIG. 5 in the bulging direction, or may be formed in a direction intersecting the width direction of the magnet insertion holes 6 to 13. . Even if the gaps 42 to 49 are formed as in the second embodiment, magnetic flux leakage and stress concentration in the support portion Y can be suppressed as in the first embodiment.

(2) The permanent magnet 30 in the first embodiment can be changed to the third embodiment shown in FIG. The permanent magnet 64 in the third embodiment is inserted into the magnet insertion holes 6 to 13 (FIG. 6 shows only a part of the pair of magnet insertion holes 6 and the pair of magnet insertion holes 7 and 13). At this time, the corner portions 65 and 66 located at the end on the d-axis side are chamfered. Since the permanent magnet 64 in the third embodiment has a shape in which the corners 65 and 66 are chamfered, a part of the permanent magnet 64 can enter the space of the gaps 22 to 29, and the width of the permanent magnet 64 can be reduced. Can be made substantially longer. Therefore, the motor efficiency can be increased without increasing the size of the rotor core 4, and the operation efficiency of the permanent magnet embedded electric motor 1 can be increased. The shape of the corner portions 65 and 66 is not limited to chamfering, and can be processed into a curved surface such as an arc surface or other shapes.

(3) The gaps 22 to 29 and 42 to 49 shown in the respective embodiments can be configured by filling a resin. The filled resin can suppress a short circuit of magnetic flux between a pair of adjacent permanent magnets 30 and 64, and reduce magnetic flux leakage. Moreover, resin can acquire the function which fixes the permanent magnets 30 and 64 to the magnet insertion holes 6-13.

(4) Although the rotor core 4 is configured by laminating a plurality of steel plates made of a magnetic material, the rotor core 4 is not limited to a structure in which only the steel plates having the shapes shown in the embodiment are laminated, and a permanent magnet can be inserted. If present, steel plates of other shapes may be mixed and laminated.

DESCRIPTION OF SYMBOLS 1 Permanent magnet buried type electric motor 2 Rotor 3 Stator 4 Rotor core 4A Outer peripheral surface 6-13 Magnet insertion hole 6A, 6B, 22A, 22B, 22C, 50, 51, 52, 61 Edge part 14-21 Notch part 22-29 , 42 to 49 Cavity 30, 64 Permanent magnet 65, 66 Corner L1 Support width L2 Permanent magnet width X Core region Y Support Z Z Center line

Claims (4)

A rotor having a rotating shaft and a stator having a coil, wherein the rotor includes a rotor core formed by laminating a plurality of steel plates in the axial direction of the rotating shaft, and a permanent magnet embedded type constituted by a permanent magnet embedded in the rotor core. In the electric motor,
At least one of the steel plates has a plurality of pairs of magnet insertion holes formed so as to spread toward the outer edge, and a notch portion that opens to the outer edge at the q-axis side end of the magnet insertion hole Are connected, and there is a gap at the d-axis side end of the magnet insertion hole, and on the outer edge side of the steel plate, a core region surrounded by a pair of the magnet insertion hole and the notch is formed, A support portion that supports the core region is formed between the pair of gap portions, and edges at both ends in the d-axis direction of the gap portion are formed in a curved shape so as to be separated from the d-axis. A permanent magnet buried type electric motor.   2. The permanent magnet-buried electric motor according to claim 1, wherein edges of the gap portion other than both ends in the d-axis direction are configured by straight lines parallel to the d-axis. The permanent magnet according to claim 1 or 2, wherein a chamfering process is applied to a d-axis side end portion of the permanent magnet in a state where the permanent magnet is inserted into the magnet insertion hole. Buried electric motor.   The permanent magnet embedding according to any one of claims 1 to 3, wherein the notch is bent and extended from the magnet insertion hole to the d-axis side and opens at an outer edge of the steel plate. Type electric motor.

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