JP2013143791A - Magnet-inclusion type synchronous machine and rotor thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotor of a magnet-inclusion type synchronous machine which includes a rare earth anisotropic bond magnet of a high orientation.SOLUTION: A rotor (1) of a magnet-inclusion type synchronous machine includes: main bodies (11) which consist of a soft magnetic material and include inclusion parts (12) evenly arranged in the periphery of a rotation center axis and consisting of gaps; and permanent magnets (M1) disposed in the inclusion parts. An outer peripheral side region from an outer peripheral side end of the permanent magnet to an outer peripheral end of the main body is a low magnetic part having magnetic permeability lower than that of the soft magnetic material. The permanent magnet is composed of a rare earth anisotropic bond magnet formed by injection molding in the inclusion part in which an orientation magnetic field is effectively formed. The low magnetic part is constituted, for example, by reforming a structure of a part of a laminated electromagnetic steel plate into an austenitic structure. By providing the low magnetic part, the orientation magnetic field at the time of injection molding is effectively distributed to the inclusion part, and the rare earth anisotropic bond magnet of the high orientation can be efficiently formed in the inclusion part.

Description

  The present invention relates to an internal magnet type synchronous machine including a rare earth anisotropic bonded magnet and a rotor thereof.

  There are various types of electric motors (simply called “motors” including generators). Recently, with the development of inverter control and the widespread use of rare earth magnets with high magnetic properties, attention has been focused on synchronous machines that can save power, have high efficiency, and expect high torque or high output.

  The synchronous machine is a motor having a permanent magnet for a field in a rotor (rotor) and an armature winding (coil) in a stator (stator), and a multiphase alternating current ( The AC motor rotates by generating a rotating magnetic field in the stator by supplying (AC). Synchronous machines are roughly classified into a surface magnet type motor (SPM) in which permanent magnets are arranged on the surface of the rotor and an embedded magnet type motor (IPM) in which permanent magnets are embedded in the rotor. Highly reliable IPM that can prevent scattering of magnets is becoming the mainstream.

  A conventional IPM is configured by inserting a sintered magnet cut or polished to a predetermined size into a slot provided in a rotor. However, when a magnetized strong rare earth sintered magnet is inserted into the slot, the magnet is easily damaged. Therefore, in Patent Document 1 below, a melted strand made of rare earth magnet powder and resin is injected and filled into a slot of a rotor in a magnetic field, cooled and solidified, and a rare-earth bonded magnet after replacement is replaced with a conventional sintered magnet. Propose to do.

Japanese Patent Application Laid-Open No. 11-206075 Japanese Patent No. 4626683

  However, Patent Document 1 merely suggests replacing the rare earth sintered magnet of IPM with a rare earth bonded magnet, and does not mention anything about the configuration of a rotor or a slot suitable for injection molding of a rare earth bonded magnet in a magnetic field. Not.

  Further, in Patent Document 2, it has been conventionally proposed to provide a nonmagnetic portion in a part of a rotor that is an iron core. Thereby, the leakage magnetic flux is reduced, and the effective magnetic flux (linkage magnetic flux) contributing to the motor output can be increased. Of course, such a low magnetic part is provided only by paying attention to a magnetic circuit formed between the rotor and the stator during motor operation, and injection of a rare earth anisotropic bonded magnet as described later. It is not directly related to the orientation magnetic field during molding.

  By the way, rare earth anisotropic magnet particles constituting rare earth anisotropic bonded magnets have much higher coercive force as well as magnetic flux density than commonly used ferrite magnet particles regardless of composition. For this reason, an orientation magnetic field higher than that of the ferrite magnet particles is required for orientation during injection molding. Therefore, in order to efficiently produce a high-performance IPM, it is important how to effectively apply an orientation magnetic field applied during injection molding of a rare earth anisotropic bonded magnet to a slot of a rotor core in which the bonded magnet is accommodated. Become.

  The present invention has been made in view of such circumstances, and provides an encapsulated magnet type synchronous machine that encloses an efficiently oriented rare earth anisotropic bonded magnet in a rotor and the rotor. Objective.

  As a result of extensive research and trial and error, the present inventor has made non-magnetic a specific region of the rotor core to control the magnetic flux density distribution in the rotor core caused by the orientation magnetic field during injection molding. I came up with that. Then, the magnetic flux density in the slot of the rotor core was efficiently increased, and a rotor including a rare-earth anisotropic bonded magnet having a higher orientation than before was successfully obtained. By developing this result, the present invention described below has been completed.

《Rotator of internal magnet type synchronous machine》
(1) The rotor of the internal magnet type synchronous machine of the present invention is provided with a main body having an internal part made of a soft magnetic material and having an air gap part (equally) arranged around the rotation center axis, and the internal part. A permanent magnet, and a magnetic permeability higher than that of the soft magnetic material in an outer peripheral region extending from an outer peripheral end of the permanent magnet to an outer peripheral end of the main body. The permanent magnet is made of a rare earth anisotropic bonded magnet injection-molded in the inner part to which an orientation magnetic field is applied.

(2) The rotor of the present invention has an efficiently oriented permanent magnet (rare earth anisotropic bonded magnet), and contributes to high performance of the internal magnet type synchronous machine. The reason is considered as follows. First, in the rotor of the present invention, the outer peripheral side region extending from the outer peripheral side end of the permanent magnet housed in the inner packet part and reaching the outer peripheral end of the main body (rotor core) has a low magnetic permeability lower than that of the soft magnetic material. Has become a department. When an orientation magnetic field is applied to the inner part (slot) with the outer peripheral side region at the time of injection molding, the orientation magnetic field does not concentrate in the outer peripheral side region having a low magnetic permeability, and the orientation of the rare earth anisotropic magnet powder Leakage magnetic flux that does not contribute to is greatly reduced.

  Conversely, the orientation magnetic field applied from the outside to the rotor during injection molding is distributed with high density in the inner part of the rotor, and the effective magnetic flux contributing to the orientation of the rare earth anisotropic magnet powder is greatly increased. To increase. Therefore, the rare earth anisotropic bonded magnet according to the present invention is injection-molded in a state in which an orientation magnetic field acts efficiently and becomes highly oriented. Although it depends on the magnitude of the applied orientation magnetic field, the rare earth anisotropic bonded magnet is molded with a high magnetic field applied from the outside. It is possible to eliminate the need for magnetization after injection molding (post-magnetization). This is effective in the case of a rare earth anisotropic bonded magnet made of rare earth anisotropic magnet powder (for example, Nd-Fe-B magnet powder or the like) which is a hardly oriented magnet powder.

  Of course, in the present invention, since the permanent magnet included in the rotor is a bonded magnet, there are many advantages compared to the case where a sintered magnet is embedded. For example, the amount of rare and expensive rare earth used can be suppressed. In addition, when using a sintered magnet, processing such as cutting and polishing is required to be housed in the slot, but when using a bonded magnet, such processing is not necessary. In addition, since no processing waste is generated, rare and expensive rare earths are not wasted.

  Furthermore, when using a sintered magnet, a chip | tip etc. will be produced when inserting in a slot, a clearance gap will be produced between slots, or the adhesive agent fixed in a slot will be needed. However, a bonded magnet integrally formed in the slot does not have the disadvantages of a sintered magnet because it is naturally firmly fixed in the slot.

  Furthermore, during operation of the synchronous machine, a large iron loss (eddy current loss and hysteresis loss) can occur in the sintered magnet, but the bonded magnet is in a state where each magnet particle is insulated by a binder resin which is an insulator. Therefore, the resulting iron loss is very small. Therefore, a synchronous machine including a rotor including a bond magnet is efficient. Moreover, since the bonded magnet is in a state where each magnet particle is coated with a binder resin, the bonded magnet has high oxidation resistance without performing surface treatment or the like.

<Internal magnet type synchronous machine>
(1) The present invention can be grasped not only as the rotor described above but also as an internal magnet type synchronous machine using the rotor. That is, the present invention includes the above-described rotor, and a stator having a coil (equally) disposed on the outer periphery of the rotor and a yoke that forms a magnetic circuit on the outer peripheral side of the coil. An internal magnet type synchronous machine characterized by the above may be used. As appropriate, the yoke includes a tooth in the coil.

(2) The synchronous machine basically rotates based on an attractive force and a repulsive force generated by a magnetic pole formed by a permanent magnet provided on the rotor and a rotating magnetic field formed by the stator on the outer periphery of the rotor. Force (magnet torque) is generated. However, unlike a surface magnet type synchronous machine, in the case of an embedded magnet type (internal magnet type) synchronous machine, a difference is easily generated between the inductance (Ld) generated in the magnetic pole and the inductance (Lq) generated between the magnetic poles. Reluctance torque based on force is also often generated in the rotor. In particular, when Ld <Lq, the reluctance torque and the magnet torque are in the same direction, and the output torque can be increased.

  Therefore, the rotor according to the present invention also adjusts the shape and arrangement of the permanent magnet (inner part) in the rotor, for example, between the adjacent magnetic poles formed by the permanent magnet and the magnet torque generated by this magnetic pole. It is preferable to have salient poles that generate reluctance torque acting in the same direction.

<< Method for manufacturing rotor of internal magnet type synchronous machine >>
Further, the present invention can be grasped not only as the above-described inner magnet type synchronous machine and its rotor, but also as a method of manufacturing the rotor. That is, the present invention relates to an internal magnet-type synchronous machine including a main body having an internal part made of a soft magnetic material and having a gap that is (equally) arranged around a rotation center axis, and a permanent magnet provided in the internal part. A method for manufacturing a rotor, wherein the binder resin is melted into the inner envelope portion having a low magnetic portion having a lower magnetic permeability than the soft magnetic material in an outer peripheral side region extending from an outer peripheral end to the outer peripheral end of the main body. An encapsulated magnet comprising an injection molding step of molding a rare earth anisotropic bonded magnet to be a permanent magnet by injection filling a molten mixture in which rare earth anisotropic magnet powder is dispersed in an oriented magnetic field It can also be grasped as a method of manufacturing a rotor of a synchronous machine.

<Others>
(1) The internal magnet type synchronous machine of the present invention includes not only an electric motor but also a generator, and the electric motor (motor) in this specification includes a generator (generator) unless otherwise specified. The internal magnet type synchronous machine of the present invention includes a Hall element in addition to the original synchronous machine in which the rotation speed changes in synchronization with the frequency of the alternating current supplied to the coil (armature winding) provided in the stator Also included is a brushless direct current (DC) motor that generates a rotating magnetic field on the stator side based on the position of the rotor detected by a detecting means such as a rotary encoder or resolver. Incidentally, since the brushless DC motor can change the rotation speed by changing the DC voltage supplied to the inverter, it is excellent in controllability like a normal DC motor.

(2) In this specification, the side close to the rotation center of the main body is referred to as “inner side” while the object or target part is viewed relatively, and the side far from the center of rotation is referred to as “outer side”. . Further, in the object or the target portion, a portion closest to the rotation center is referred to as an “inner peripheral end”, and a portion farthest from the rotation center with respect to a certain direction is referred to as an “outer peripheral end”. For example, in the case of the main body (object), if the outer peripheral shape is a complete circular shape, the arc portion becomes the “outer peripheral end” when viewed from any direction. However, if the outer peripheral shape is uneven, the “outer peripheral edge” varies depending on the viewing direction, and the outer peripheral side of the top of the convex portion may be the “outer peripheral end”, or the outer peripheral side of the bottom of the concave portion may be the “outer peripheral end”. ". Of these “outer peripheral ends”, the one farthest from the center of rotation is referred to as the “outermost end”.

  Further, the “inner peripheral end side” means the inner peripheral side of the above “inner peripheral end”. “Outer peripheral side” means the outer peripheral side of the above “outer peripheral end”. In addition, the shape of the “end” in this specification may be linear or planar, and “end” means the vicinity of the “end”.

(3) Unless otherwise specified, “x to y” in this specification includes a lower limit value x and an upper limit value y. Any numerical value included in various numerical values or numerical ranges described in the present specification can be newly established as a range such as “ab” as a new lower limit value or upper limit value.

It is principal part sectional drawing of the synchronous motor which is 1st Example of this invention. It is a top view of the electromagnetic steel plate which comprises the rotor core. It is a magnetic flux density distribution figure which shows the mode of the orientation magnetic field applied to the rotor. It is a principal part enlarged view of the magnetic flux density distribution figure. It is a magnetic flux density distribution figure which shows the mode of the orientation magnetic field applied to a rotor without a modification part. It is a principal part enlarged view of the magnetic flux density distribution figure. It is a top view of the rotor which concerns on the 2nd Example of this invention. It is a top view of the rotor which concerns on the 3rd Example of this invention. It is a top view of the rotor which concerns on 4th Example of this invention. It is a top view of the rotor which concerns on 5th Example of this invention. It is the elements on larger scale which show the modification of the bridge | crosslinking part of a rotor core, and the modification part provided in the bridge | crosslinking part. It is the elements on larger scale which show the modification of the modification part. It is the elements on larger scale which show the other modification of the modification part. It is the elements on larger scale which show another modification of the modification part.

  The contents described in this specification can be applied not only to the internal magnet type synchronous machine (hereinafter also simply referred to as “synchronous machine”) of the present invention but also to a rotor or the like used therefor. Matters related to the manufacturing method can also be components related to products if understood as product-by-process. And one or two or more arbitrarily selected from the matters described in the present specification can be added to the above-described components of the present invention. Which embodiment is the best depends on the target, required performance, and the like.

《Rotator of internal magnet type synchronous machine》
(1) Main body The main body of the rotor is made of a soft magnetic material, and is usually made of a laminated body of electromagnetic steel sheets with insulation coating on both sides, a dust core formed by press-molding insulation-coated metal particles, or the like. The soft magnetic material may be any material, but is preferably an iron-based material such as pure iron, silicon steel, or alloy steel.

(2) Inner part The inner part of the rotor is provided in the main body and includes a gap for disposing a permanent magnet. There are at least two inner inclusions for containing the permanent magnets serving as magnetic poles, and these are usually arranged evenly around the rotation center axis of the main body.

  Regardless of the shape of the inner packet part, it is appropriately adjusted according to the specifications of the synchronous machine. For example, the inner packet part may be a radial inner packet part that extends linearly from the center in the radial direction, or may be a convex inner packet part that is convex toward the inner periphery. It is preferable that the convex inclusion portion has a smooth curved shape because a high orientation magnetic field can be uniformly applied to the entire inclusion portion. For example, a curved inner part (including a U-shaped inner part, a V-shaped inner part, a J-shaped inner part, etc.) that is gently curved toward the inner peripheral side is preferable. From the same viewpoint, it is preferable that the inner packet part has a uniform groove width. In other words, it is preferable that there is no sudden shape change or dimensional change in which the applied orientation magnetic field tends to concentrate locally.

  Furthermore, the inner packet part may be a multi-layered inner packet part in the radial direction. When the multi-layered inner part is used, the reluctance torque can be increased. The number of layers of the multilayer-type inclusion is not limited, but two or three layers are preferable for achieving both the characteristics of the synchronous machine and the productivity.

  In the present invention, since the permanent magnet is made of an injection-molded rare earth anisotropic bonded magnet (also simply referred to as “bonded magnet”), the permanent magnet has the shape of the inner envelope portion regardless of the shape of the inner envelope portion. Is basically in line with However, since it is possible to perform injection molding by interposing a spacer or the like in the inner packet part, the shape of the inner packet part may not match the shape of the permanent magnet. In addition, as will be described later, when both end portions in the longitudinal direction of the inner packet part are low magnetic parts (particularly, complementary parts) made of gaps, the shapes of the permanent magnet and the inner packet part may not match.

(3) Low magnetic part The low magnetic part does not ask | require the specific magnetic permeability, as long as the magnetic permeability is lower than the soft magnetic material which comprises a main body. For example, a void portion (a portion including air), a filling portion in which the void portion is filled with a resin having a low magnetic permeability (appropriately referred to as “non-magnetic”), and a soft magnetic material constituting the rotor body are partially The low magnetic part is constituted by the modified part, the replacement part obtained by partially replacing the soft magnetic material with a nonmagnetic material, and the like.

  Here, the soft magnetic material can be modified, for example, by changing a ferrite structure or a martensite structure having ferromagnetism into a nonmagnetic austenite structure. Such a modification can be performed, for example, by partially dissolving, dissolving, or diffusing a modifying material (austenite stabilizing element) containing Ni, Cr, or the like into an iron-based soft magnetic material.

  Further, ferromagnetic martensitic stainless steel, cold-worked metastable austenitic stainless steel, or the like may be modified by locally heating to transform it into a nonmagnetic austenitic structure. Note that local heating can be performed by irradiation with a laser or an electron beam, high-frequency induction heating, or the like.

  By the way, the low magnetic part according to the present invention is provided in the outer peripheral region so that a high orientation magnetic field is uniformly induced to the part (all or part of the inner part) where the bonded magnet is injection-molded. It's enough. Therefore, the entire outer peripheral region need not be the low magnetic part, and only a part thereof may be the low magnetic part.

  However, the low magnetic part is preferably continuous from the outer peripheral side end of the permanent magnet (bonded magnet) to the outer peripheral end of the main body. Thereby, the orientation magnetic field applied from the outside of the main body does not contribute to the orientation of the bonded magnet, but is concentrated on a specific portion (for example, a bridge portion described later) in the outer peripheral side region and is prevented from passing through in a short circuit.

  Moreover, the low magnetic part does not need to be homogeneous or homogeneous as a whole, and may be a combination of the above-described void part, filling part, reforming part and the like as appropriate. For example, consider a case where the main body has a bridging portion (a part of the main body) made of a soft magnetic material extending in the circumferential direction in the outer peripheral region and a void portion on the inner peripheral side of the bridging portion. By providing the reforming part at least in part of the bridging part, the low magnetic part according to the present invention is constituted by the reforming part and a void formed on the inner peripheral side of the bridging part. .

In the present specification, the above-described gap formed on the inner peripheral side of the bridging portion and the filling portion formed by filling the gap with a nonmagnetic material or the like are referred to as a complement portion. As described above, the complementary portion can also constitute a part of the low magnetic portion according to the present invention. By this complementary portion, the distortion of the alignment magnetic field generated on the inner peripheral end side of the bridging portion is absorbed, and the alignment magnetic field aligned in the target direction on the inner peripheral side of the complementary portion (that is, the portion where the molten mixture is injected and filled) is generated. Can be formed. Thereby, the fall of the orientation degree of the outer peripheral edge part of a bond magnet can be suppressed. In addition, the complementary portion prevents the orientation magnetic field during injection molding from being concentrated in a short-circuit manner at the outer peripheral end of the bonded magnet.
Further, the complementing unit can increase the effective magnetic flux (linkage magnetic flux) when the synchronous machine is operated.

  Furthermore, the modified part provided in the bridging part is provided so as to penetrate the bridging part in the radial direction (the direction in which the inner packet part extends to the outer peripheral side) or the bridging part has a high magnetic resistance so that the magnetic flux of the orientation magnetic field does not concentrate It is preferable to be provided as follows. This bridging portion may be provided at the outermost peripheral end portion of the main body, or may be provided at the inner peripheral side thereof. In any case, by providing the reforming portion that penetrates the bridging portion in the radial direction, a low magnetic portion that is continuous from the outer peripheral end of the bonded magnet to the outer peripheral end of the main body can be easily formed as described above.

  In addition, when a bridge | crosslinking part is provided in the inner peripheral side rather than the outermost periphery end of a main body, the outermost periphery end of a bridge | crosslinking part becomes a bottom position slightly dented with respect to the assumed outermost diameter of a main body. Arranging the bridging portion in this way is advantageous because even when the outer circumferential end surface is bulged or distorted when the bridging portion is modified, the outermost diameter of the rotor is not affected.

  The low magnetic part is not limited to the outer peripheral region, and may be provided in another region where the orientation magnetic field can be effectively induced to the injection molding portion of the bonded magnet. For example, in order to secure the strength of the main body and the like, when providing a connecting portion that connects the outer peripheral side and the inner peripheral side of the curved inner envelope portion described above, the connecting portion is a low magnetic portion having a lower magnetic permeability than a soft magnetic material ( Low magnetic coupling part).

<Rare earth anisotropic bonded magnet>
(1) Raw material A rare earth anisotropic bonded magnet basically comprises a rare earth anisotropic magnet powder and a binder resin. The kind of rare earth anisotropic magnet powder is not particularly limited, and examples thereof include Nd—Fe—B magnet powder, Sm—Fe—N magnet powder, and Sm—Co magnet powder. These rare earth anisotropic magnet powders may be composed of not only one type but also a plurality of types. Incidentally, the plurality of types of magnet powders are not limited to those having different component compositions but may have different particle size distributions. For example, a combination of coarse powder and fine powder of Nd-Fe-B magnet powder or a combination of coarse powder of Nd-Fe-B magnet powder and fine powder of Sm-Fe-N magnet powder may be used. By using such rare earth anisotropic magnet powder, the filling rate of the magnet powder in the bonded magnet can be improved, and a bonded magnet exhibiting a high magnetic flux density can be obtained. Furthermore, various isotropic magnet powders, ferrite magnet powders, and the like may be mixed in the rare earth anisotropic magnet powder.

  As the binder resin, known materials including rubber can be used. For example, polyethylene, polypropylene, polystyrene, acrylonitrile / styrene resin, acrylonitrile / butadiene / styrene resin, methacrylic resin, vinyl chloride, polyamide, polyacetal, polyethylene terephthalate, ultrahigh molecular weight polyethylene, polybutylene terephthalate, methylpentene, polycarbonate, polyphenylene sulfide, It is preferable to use a thermoplastic resin such as polyetheretherketone, liquid crystal polymer, polytetrafluoroethylene, polyetherimide, polyarylate, polysulfone, polyethersulfone, and polyamideimide. Also, thermosetting resins such as epoxy resin, unsaturated polyester resin, amino resin, phenol resin, polyamide resin, polyimide resin, polyamideimide resin, urea resin, melamine resin, urea resin, direal phthalate resin, polyurethane, etc. should be used as appropriate. Can do.

(2) Injection molding The rare earth anisotropic bonded magnet according to the present invention is formed by injection-filling a molten mixture obtained by heating and melting the pellets made of the above-described raw material into an inner part to which an orientation magnetic field is applied, and then solidifying by cooling. Is done. Each condition of the injection molding is appropriately adjusted in consideration of the characteristics of the raw material, the filling amount, the cooling property of the inner packet part, and the like. For example, the heating temperature (temperature of the molten mixture) during injection molding is preferably less than the Curie point of the rare earth anisotropic magnet powder.

  In addition, the orientation magnetic field needs to be applied before the molten mixture is solidified, but may start from the beginning of injection molding or from the middle of injection molding. For example, when a permanent magnet is used for the orientation magnetic field source, it may be from the beginning of injection molding, and when an electromagnet is used, it may be from the middle of injection molding. The application mode of the orientation magnetic field (distribution of magnetic flux density formed in the rotor) is appropriately adjusted according to the shape of the inner packet part and the specifications of the synchronous machine.

《Use of internal magnet type synchronous machine》
The internal magnet type synchronous machine of the present invention may be used for any purpose. For example, a motor for a vehicle driving motor used in an electric vehicle, a hybrid vehicle, a railway vehicle or the like, a motor for home appliances used in an air conditioner, a refrigerator, a washing machine, or the like. It is suitable for such as.

The present invention will be described more specifically with reference to examples.
<< Internal magnet type synchronous machine: First embodiment >>
FIG. 1A shows a cross-sectional view of the stator S and the rotor 1 of the synchronous motor SM1, which is an embodiment of the internal magnet type synchronous machine of the present invention. The synchronous motor SM1 shown in FIG. 1A is a 6-pole 18-slot type. The synchronous motor SM1 is used as a motor for driving a car, a motor for home appliances, or the like. Hereinafter, the stator S and the rotor 1 will be described in detail.

(1) Stator The stator S is composed of laminated electromagnetic steel plates, and includes an annular yoke Sa, teeth Sb that protrude evenly from the yoke Sa toward the center, and slots Sc formed between adjacent teeth Sb. Each slot Sc accommodates an electromagnetic coil (not shown) distributed around the teeth Sb. By supplying inverter-controlled three-phase alternating current to each electromagnetic coil, a rotating magnetic field having a synchronous speed corresponding to the frequency and the number of poles is generated in the stator S.

(2) Rotor As shown in FIG. 1B, the rotor 1 includes a center hole 191 and six equal-width long grooves 121 that are uniformly arranged around the center and penetrated in a curved shape (convex shape) on the inner peripheral side. A disk-shaped electromagnetic steel plate 111 (soft magnetic material) having By laminating the electromagnetic steel plates 111, a substantially cylindrical rotor core 11 (main body) extending in the rotation center axis direction (direction perpendicular to the paper surface of FIG. 1A) is formed, and a permanent magnet M1 described later is injected into the long groove 121. A slot 12 (inner part) extending in the same direction is formed, and the center hole 191 becomes a shaft hole 19 extending in the same direction in which a shaft (not shown) of the synchronous motor SM1 is inserted.

  The outer peripheral side end of the slot 12 is a modified part 141 (low magnetic part) obtained by modifying the outer peripheral end (bridged part) of the rotor core 11 made of a soft magnetic material (laminated magnetic steel sheet) into a nonmagnetic austenite structure. It has become. This reforming process was performed by arranging a Ni—Cr wire at the outer peripheral end of the rotor core 11 which is a processing target part, and irradiating it with a carbon dioxide gas laser to cause partial melting (Japanese publication). (Patent publication: JP-A-6-79483).

  A permanent magnet M1 made of a rare earth anisotropic bonded magnet was formed by injection molding in a magnetic field in the slot 12 having the modified portions 141 on the outer peripheral sides at both ends. Specifically, first, the rotor core 11 is set in a magnetic field injection filling device (not shown), and an orientation magnetic field (see FIGS. 2A and 2B) in which polarities are alternately different between adjacent slots 12 is supplied to each slot 12. Apply toward.

  These slots 12 are injected and filled with a molten mixture obtained by heating and melting pellets made of Nd—Fe—B based anisotropic magnetic powder, Sm—Fe—N based magnetic powder and polyphenylene sulfide resin (binder resin). Thereafter, the molten mixture in the slot 12 was solidified by cooling in the mold of the injection filling apparatus in the magnetic field, and the permanent magnet M1 integrally formed in the slot 12 was formed. Thus, the rotor 1 was obtained in which the permanent magnet M1 curved toward the inner peripheral side was annularly included.

  In this example, an orientation magnetic field was applied to the slot 12 from the start of filling of the molten mixture to the end of filling. At this time, the orientation magnetic field was 0.7 T, the temperature of the molten mixture was 300 ° C., the injection pressure was 80 MPa, and the injection speed was 80 mm / sec.

  As a result, the magnet particles in the permanent magnet M1 are not only oriented during injection molding in a magnetic field, but are also magnetized at the same time, and the permanent magnet M1 has already exhibited a high magnetic flux density. For this reason, in this embodiment, there was no need to separately perform post-magnetization.

(3) Motor A shaft (not shown) is fitted and attached to the shaft hole 19 of the rotor 1 including the permanent magnet M1. The rotor 1 is rotatably disposed in the stator S. At this time, the gap formed between the outer peripheral end face of the rotor 1 and the inner end face of the teeth Sb was made constant. Thus, the synchronous motor SM1 was obtained. When this synchronous motor SM1 is connected to an inverter-controlled power supply and a rotating magnetic field is generated in the stator S, the rotor 1 rotates in synchronization therewith.

  In the synchronous motor SM1, the inductance Lq1 in the q-axis direction shifted by π / 2 (electrical angle) from the d-axis direction is larger than the inductance Ld1 in the d-axis direction passing through the center of the permanent magnet M1. For this reason, not only the magnet torque Tm1 by the permanent magnet M1 but also the reluctance torque Tr1 based on the inductance difference (Lq1-Ld1) is generated in the synchronous motor SM1 in the same direction as the magnet torque Tm1. Therefore, the synchronous motor SM1 exhibits a larger output torque. In the following examples, the definitions of the d-axis and the q-axis are the same.

(4) Low Magnetic Part By the way, when the molten mixture was injected and filled into the slot 12, spacers made of a nonmagnetic material (resin or the like) were interposed on both inner end sides of the slot 12. For this reason, complementary portions 142 formed of gaps are formed on both ends of the permanent magnet M1 formed in the slot 12 (between the outer peripheral side end M1a of the permanent magnet M1 and the inner peripheral side end 141a of the reforming portion 141). It was done.

  Similar to the above-described reforming unit 141, the complementing unit 142 is a part having a magnetic permeability that is orders of magnitude smaller than that of the rotor core 11. Therefore, the complementing part 142 can also constitute the low magnetic part of the present invention, like the reforming part 141. Therefore, the reforming unit 141 and the complementing unit 142 are collectively referred to as a low magnetic unit 14 as appropriate.

  The distribution (magnetic flux density distribution) of the orientation magnetic field at the time of injection molding in the rotor core 11 having the low magnetic part 14 was simulated. The result is shown by magnetic field lines in FIG. 2A. FIG. 2B shows an enlarged view of the periphery (part □ shown in FIG. 2A) of the slot 12 (particularly, the low magnetic portion 14). At this time, the orientation magnetic field is supplied from the permanent magnet Da provided in the injection filling apparatus in the magnetic field toward the slot 12 via the yoke Db. The permanent magnet Da and the yoke Db are appropriately referred to as an orientation magnetic field source D as appropriate.

  A similar simulation was performed for the rotor core 11 ′ in which the reforming portion 141 was not provided in the rotor core 11, and the results are shown in FIGS. 3A and 3B.

  As is apparent from both simulation results, by providing the reforming portion 141, the leakage magnetic flux passing through the outer peripheral end portion (bridge portion) of the rotor core 11 without passing through the slot 12 is greatly reduced. Conversely, the orientation magnetic field passing through the slot 12 increased overall. For example, due to the magnetic field supplied from the orientation magnetic field source D, the magnetic field in the slot 12 was 0.5 T in the rotor core 11 ′ but 0.7 T in the rotor core 11.

  Accordingly, as described above, it is effective to simply provide the complementary portions 142 at both ends of the slot 12, but by providing the reforming portion 141, the orientation magnetic field is more effective in the slot 12 in which the permanent magnet M1 is injection molded. Was found to be formed.

<< Second Example >>
FIG. 4 shows a rotor 2 which is another embodiment of the rotor of the internal magnet type synchronous machine of the present invention. The rotor 2 includes a first slot 22 and a second slot 23 obtained by dividing the slot 12 of the rotor 1 and the permanent magnet M1 into two radial layers, and a first permanent magnet M21 and a second permanent magnet M22 in the rotor core 21. Have. Also in the rotor 2, the amount of Nd—Fe—B based anisotropic magnet powder used was the same as that in the rotor 1. Accordingly, each of the first slot 22 and the second slot 23 formed in the rotor 2 has a thickness in the radial direction of about half that of the slot 12 of the rotor 1. Similarly, the first permanent magnet M21 and the second permanent magnet M22 that are injected into the first slot 22 and the second slot 23 in a magnetic field and integrally formed also have a radial thickness of the permanent magnet M1 of the rotor 1, respectively. It is about half of.

  On the outer peripheral side of the first slot 22 and the second slot 23, similarly to the reforming part 141 and the complementing part 142 of the rotor 1, the reforming part 241 and the complementing part 242 (both are referred to as the low magnetic part 24). Then, the reforming part 251 and the complementing part 252 (both are referred to as the low magnetic part 25) were formed. For this reason, the point that the orientation magnetic field is effectively applied to the slots 22 and 23 by the low magnetic portions 24 and 25 is the same as in the case of the rotor 1.

  By inserting a shaft (not shown) into the shaft hole 29 of the rotor 2 and attaching it to the stator S, the synchronous motor SM2 (not shown) can be obtained. Unlike the synchronous motor SM1, the synchronous motor SM2 has a magnetic path 217 made of a soft magnetic material (laminated magnetic steel sheet) between the first slot 22 and the second slot 23. For this reason, the inductance Lq2 in the q-axis direction of the present embodiment is larger than the inductance Lq1 described above. On the other hand, since the magnet amounts of the first permanent magnet M21 and the second permanent magnet M22 are substantially the same as the permanent magnet M1, the inductance Ld2 is not much different from the inductance Ld1. As a result, the synchronous motor SM2 can generate a reluctance torque larger than that of the synchronous motor SM1.

  The total amount of the first permanent magnet M21 and the second permanent magnet M22 is equal to that of the permanent magnet M1, but if the total amount is larger than that of the permanent magnet M1, the synchronous motor SM2 is larger than the synchronous motor SM1. Torque can also be generated.

《Third embodiment》
FIG. 5 shows a rotor 3 that is another embodiment of the rotor of the internal magnet type synchronous machine of the present invention. The rotor 3 has a loose substantially V-shaped slot 32 and a permanent magnet M3 in the rotor core 31 in which the slot 12 and the permanent magnet M1 of the rotor 1 are protruded larger toward the inner peripheral side. Only the reforming portion 34 similar to the reforming portion 114 is formed at the outer peripheral end portion of the slot 32 (the outer peripheral end portion / bridging portion of the rotor core 31). The point that the orientation magnetic field is efficiently applied to each slot 32 by the reforming part 34 (low magnetic part) is the same as in the case of the rotor 1.

  When a shaft (not shown) is fitted and attached to the shaft hole 39 of the rotor 3, a synchronous motor SM3 (not shown) is obtained. When a rotating magnetic field is generated in the stator S, the rotor 3 rotates in synchronization therewith. It becomes like this.

  In the synchronous motor SM3 of the present embodiment, since the permanent magnet M3 penetrates deeply in the center direction, the inductance Lq3 in the q-axis direction is smaller than the inductance Lq1 and the like. On the other hand, since the radial width of the permanent magnet M3 is substantially the same as that of the permanent magnet M1, the inductance Ld3 is not much different from the inductance Ld1 and the like. For this reason, the reluctance torque Tr3 generated in the synchronous motor SM3 is smaller than the reluctance torque Tr1 of the synchronous motor SM1. However, since the magnet surface area of the permanent magnet M3 is larger than that of the permanent magnet M1, the magnet torque Tm3 of the synchronous motor SM3 is larger than the magnet torque Tm1 of the synchronous motor SM1.

<< 4th Example >>
FIG. 6 shows a rotor 4 which is another embodiment of the rotor of the internal magnet type synchronous machine of the present invention. The rotor 4 includes a first slot 42 and a second slot 43 obtained by dividing the slot 32 and the permanent magnet M3 of the rotor 3 into two symmetrical with respect to the radius, and a first permanent magnet M41 and a second permanent magnet M42. In the rotor core 41.

  A reforming portion 44 and a reforming portion 45 are formed at the outer peripheral side end portions (bridge portions) of the first slot 42 and the second slot 43, respectively. The point that the orientation magnetic field is effectively applied to the slots 42 and 43 by these reforming portions 44 and 45 is the same as in the case of the rotor 3.

  The connecting portion 47 located between the inner peripheral side of the first slot 42 and the second slot 43 functions to connect the inner peripheral side and the outer peripheral side of the rotor core 47 divided by the slots 42 and 43. By providing this connecting portion 47, the strength of the rotor core 47 and thus the rotor 4 (particularly the strength in the radial direction) can be significantly improved.

  When the connecting portion 47 is made of a soft magnetic material, an orientation magnetic field at the time of injection molding can leak through the connecting portion 47. For this reason, the magnetic flux density in the vicinity of the inner peripheral ends of the slots 42 and 43 can be lowered. However, since the connecting portion 47 is deep on the inner peripheral side of the rotor core 47 and has a narrow width, the decrease in the orientation magnetic field is not so great. If a decrease in the orientation magnetic field becomes a problem, the connecting portion 47 may be made non-magnetic by modification or the like. Thereby, the leakage magnetic flux in the connection part 47 is remarkably reduced, and the orientation magnetic field can be effectively applied to the entire slots 42 and 43. Thus, according to the present embodiment, the strength of the rotor core 47 can be significantly improved while suppressing a decrease in the orientation magnetic field applied to the slots 42 and 43.

<< 5th Example >>
FIG. 7 shows a rotor 5 which is another embodiment of the rotor of the internal magnet type synchronous machine of the present invention. The rotor 5 includes six linear slots 52 arranged radially and permanent magnets M5 integrally formed in the slots 52 by injection molding in the rotor core 51.

  A reforming portion 54 is formed at the outer peripheral end of the rotor core 51. Further, a non-magnetically modified annular reforming portion 57 is also formed at the inner peripheral end of the rotor core 51. The reforming part 57 is formed so as to surround the shaft hole 59, and the inner peripheral side end of each slot 52 is connected to the reforming part 57. The point that the orientation magnetic field is effectively applied to the slot 52 by the reformers 54 and 57 is the same as in the other embodiments.

  The portion related to the reforming portion 57 may be replaced with a low magnetic member made of nonmagnetic austenitic stainless steel or the like. At this time, a portion corresponding to the reforming portion 57 may be replaced with another member made of a low magnetic member, or a shaft having a low magnetic member at least in the corresponding portion may be fitted into the rotor core 51.

  When the rotor 5 fitted with a shaft (not shown) fitted into the shaft hole 59 is rotatably disposed in the stator S, a synchronous motor SM5 (not shown) is obtained. Since this synchronous motor SM5 has a small difference between the inductance Ld5 in the d-axis direction and the inductance Lq5 in the q-axis direction, the reluctance torque generated in the synchronous motor SM5 is much smaller than in the other embodiments.

  As described above, the synchronous motor SM3, the synchronous motor SM4, and the synchronous motor SM5 having a small reluctance torque are used at a relatively low rotational speed, and a motor such as an electric power steering (EPS) that requires a small cogging torque and torque ripple. It is suitable for.

<Sixth embodiment>
Various examples in which the rotor core 11 and the low magnetic part 14 (particularly the modified part 141) according to the first example are changed are shown in FIGS. 8A to 8D. In each figure, the outer peripheral side region E and the vicinity thereof of a permanent magnet M6 having the same form as the permanent magnet M1 are shown enlarged. In addition, the same code | symbol was attached | subjected to the part which is common between each figure.

(1) The rotor core 61 shown in FIG. 8A has a virtual outer periphery in which the outermost peripheral end of the rotor core 11 formed with the reforming portion 141 shown in FIG. 1A is slightly extended to the inner peripheral side (the circumferential direction of the rotor core 61). It has a bridging portion 640 moved to the inner peripheral side from the end l and a gap portion 642 formed on the inner peripheral side. FIG. 8A shows a modified portion 641 in which a part of the bridging portion 640 is uniformly nonmagnetically modified in the circumferential direction.

  The entire bridging portion 640 may be non-magnetically modified. However, if the width of the remaining portion that has not been non-magnetically modified is narrowed as shown in FIG. 8A, the magnetoresistance of that portion is increased. it can. If it does so, it can avoid that the magnetic flux of an orientation magnetic field concentrates on the bridge | crosslinking part 640, and can induce a high orientation magnetic field to the permanent magnet M6 effectively.

(2) FIG. 8B shows a modified portion 741 that has been nonmagnetically modified so as to penetrate substantially the center of the bridging portion 640 of the rotor core 61 in the radial direction (the direction in which the permanent magnet M6 extends to the outer peripheral side). . In this case, the continuous low magnetic part 74 is formed in the range (outer peripheral region D) from the outer peripheral end M6a of the permanent magnet M6 to the outer peripheral end 640a of the bridging part 640 by the gap 642 and the modified part 741. . As a result, both sides of the rotor core 61 sandwiching the bridging portion 640 from the circumferential direction are substantially blocked by the continuous low magnetic portion 74. Thus, a highly oriented magnetic field can be more effectively induced to the permanent magnet M6.

(3) FIG. 8C shows a case where a triangular reforming portion 841 is provided in the approximate center of the bridging portion 640 of the rotor core 61. The apex portion of the modified portion 841 does not reach the inner peripheral end of the bridging portion 640. For this reason, a portion made of a soft magnetic material that has not been nonmagnetically modified remains continuously in the circumferential direction on the inner peripheral end side of the bridging portion 640. However, in this case as well, as in the case shown in FIG. 8A, the magnetic resistance increases in the vicinity of the apex of the reforming portion 841. For this reason, the magnetic flux of an orientation magnetic field does not concentrate on the bridge | crosslinking part 640, but a high orientation magnetic field is induced | guided | derived to the permanent magnet M6 effectively.

(4) FIG. 8D shows a case where triangular reforming portions 941 and 942 are juxtaposed in the circumferential direction on the bridging portion 640 of the rotor core 61. Also in the case of the modified portions 941 and 942, since the apex portions thereof do not reach the inner peripheral end of the bridging portion 640, the portion made of the soft magnetic material that is not non-magnetically modified is the inner circumference of the bridging portion 640. It remains continuously in the circumferential direction on the end side.

  However, in this case, the magnetic resistance in the circumferential direction of the bridging portion 640 becomes larger than in the case shown in FIG. 8C. Therefore, in the case of FIG. 8D, the magnetic flux of the orientation magnetic field is less likely to be concentrated by the bridging portion 640 than in the case of FIG. 8C, and the high orientation magnetic field is more effectively induced to the permanent magnet M6.

  Incidentally, by reducing the width (radial direction) of the portion made of the soft magnetic material in the bridging portion 640, the circumferential magnetic resistance of the bridging portion 640 can be increased, and the magnetic flux of the orientation magnetic field can be prevented from concentrating there. . However, in order to improve the strength of the rotor core 61, it is necessary to ensure an appropriate width for the bridging portion 640. Therefore, in consideration of the strength of the rotor core 61 and the magnetic flux density distribution of the bridging portion 640, the width of the bridging portion 640 and the shapes and sizes of the modified portions 641, 741, 841, 941, 942 may be appropriately determined. .

SM1 synchronous motor (internal magnet type synchronous machine)
S Stator M1 Permanent magnet (rare earth anisotropic bonded magnet)
1 Rotor 11 Rotor core (main body)
12 slots (inner part)
14 Low magnetic part 141 Modification part 142 Complement part

Claims (10)

A main body having an inner packet part made of a soft magnetic material and having a gap disposed around the rotation center axis;
A permanent magnet provided in the inner packet part;
A rotor of an internal magnet type synchronous machine comprising:
At least in the outer peripheral side region extending from the outer peripheral end of the permanent magnet to the outer peripheral end of the main body, has a low magnetic part having a lower magnetic permeability than the soft magnetic material,
The rotor of an internal magnet type synchronous machine, wherein the permanent magnet is a rare earth anisotropic bonded magnet injection-molded in the internal part to which an orientation magnetic field is applied.   The rotor of the internal magnet type synchronous machine according to claim 1, wherein the low magnetic part is continuous from an outer peripheral side end of the permanent magnet to an outer peripheral end of the main body.   The internal magnet according to claim 1, wherein at least a part of the low magnetic portion is a modified portion obtained by at least partially modifying a bridging portion extending in the circumferential direction of the main body in the outer peripheral region. Type synchronous machine rotor.   The rotor of an internal magnet type synchronous machine according to claim 3, wherein the reforming part is located on the inner peripheral side of the outermost peripheral end of the main body.   At least a part of the low magnetic part is filled with a low magnetic material having a lower magnetic permeability than the soft magnetic material in the gap formed in the outer peripheral side region or on the inner peripheral side of the bridging part. The rotor of the internal magnet-type synchronous machine according to claim 3 or 4, further comprising a complementary portion comprising a filled portion.   The rotor of the internal magnet type synchronous machine according to any one of claims 1 to 5, wherein the internal packet part is a curved internal packet part that is curved toward an inner peripheral side.   The rotor of an internal magnet type synchronous machine according to claim 6, wherein the main body has a connecting portion that connects an inner peripheral side and an outer peripheral side of the curved inner envelope portion.   The rotor of an internal magnet type synchronous machine according to claim 7, wherein the connecting portion is a low magnetic connecting portion having a lower magnetic permeability than the soft magnetic material. A rotor according to any one of claims 1 to 8,
A stator having a coil disposed on the outer periphery of the rotor and a yoke constituting a magnetic circuit on the outer peripheral side of the coil;
An internal magnet type synchronous machine comprising:   The internal magnet type synchronous machine according to claim 9, wherein the rotor has a salient pole that generates a reluctance torque that acts in the same direction as a magnet torque generated by the magnetic pole between adjacent magnetic poles formed by the permanent magnet. .