Magnet-included synchronous machine and rotor thereof

Abstract

To increase the torque of a motor using a rare-earth anisotropic bond magnet and simplify a production process.SOLUTION: A rotor 1 of a magnet-included synchronous machine includes a main body having an internal part consisting of a stainless magnetic plate 10 and consisting of a cavity equally disposed around a rotation center axis. The internal part is filled with a rare-earth anisotropic bond magnet. The rotor has a non-magnetic part formed by reforming an unmagnetized stainless magnetic plate in an outer periphery region extending from one end part of a permanent magnet M to the other end part of an adjacent permanent magnet.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an internal magnet type synchronous machine that contains a rare earth bonded magnet and a rotor thereof. [Background technology]

[0002] There are various types of electric motors (including generators, simply called "motors"). Recently, with the development of inverter control and the widespread use of rare earth magnets with high magnetic properties, synchronous machines, which are energy-saving, highly efficient, and capable of high torque or output, have been attracting attention.

[0003] A synchronous machine is a motor that has a permanent magnet for the field in its rotor and an armature winding (coil) in its stator; it is an AC motor that rotates by generating a rotating magnetic field in the stator when polyphase alternating current (AC) is supplied to the armature winding. Synchronous machines are broadly divided into surface permanent magnet motors (SPM), in which permanent magnets are arranged on the surface of the rotor, and interior permanent magnet motors (IPM), in which permanent magnets are embedded inside the rotor; IPMs, which are highly reliable and prevent magnets from scattering, are currently becoming mainstream. Furthermore, efforts are being made to increase the rotation speed in order to increase the output of IPM motors. Currently, neodymium sintered magnets are the most commonly used permanent magnets, but as rotation speeds increase, heat generation becomes a serious problem, and a change to rare earth bonded magnets is being considered.

[0004] Another problem with sintered Nd magnets is that conventional IPMs are constructed by inserting sintered magnets that have been cut and ground to a specified size and magnetized to saturation into slots (contained parts) in the rotor. However, when inserting a strong magnetized rare earth sintered magnet into a slot, the magnet is prone to damage. Therefore, Patent Document 1 discloses replacing conventional sintered magnets with injection-molded rare earth bonded magnets, in which molten strands made of rare earth magnets and resin are injected into rotor slots in a magnetic field and then cooled and solidified. For these reasons, in order to increase the rotation speed and output of IPM motors, the adoption of injection-molded rare earth bonded magnets, which are a replacement for Nd sintered magnets, is being considered. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-206075 [Patent Document 2] Patent No. 4626683 [Patent Document 3] JP 2013-1433791 A [Patent Document 4] Patent No. 6868174 [Patent Document 5] Patent No. 7125684 Summary of the Invention [Problem to be solved by the invention]

[0006] However, Patent Document 1 merely proposes replacing the rare earth sintered magnets of IPM with rare earth bonded magnets, and makes no mention of rotor or slot configurations suitable for injection molding of rare earth bonded magnets in a magnetic field.

[0007] Patent Document 2 proposes providing a non-magnetic part in a part of the rotor, which is an iron core. This reduces leakage flux and can increase the effective flux (flux linkage) that contributes to the motor output. However, such non-magnetic parts are merely arranged with attention paid to the magnetic circuit formed between the rotor and stator when the motor is in operation, and are not related to the aligning magnetic field during injection molding of rare earth bonded magnets, as described below.

[0008] Patent Document 3 describes how the rare earth anisotropic magnet particles that make up rare earth bonded magnets, regardless of composition, have much higher magnetic flux density and coercive force than the commonly used ferrite magnet particles, and therefore require a higher aligning magnetic field for orientation during injection molding than ferrite magnet particles. Therefore, in order to efficiently produce high-performance IPMs, a method is disclosed in which the aligning magnetic field applied during injection molding of the rare earth anisotropic bonded magnet is effectively applied to the slots of the rotor core in which the bonded magnets are housed. The non-magnetic parts are modified by laser welding, which transfers alloy elements, but the modified parts are very uneven and the shape changes, so the post-modification processing, such as surface grinding and shape correction, is complicated and not practical. In fact, this application was abandoned without a request for examination. Naturally, it is not used industrially. However, rare earth bonded magnets are inferior in magnetic performance to sintered neodymium magnets, and so tend to result in reduced motor torque, so measures to increase torque are desired.

[0009] The present invention was made in consideration of these circumstances, and aims to change the rotor body material from a magnetic material to a stainless steel magnet, thereby increasing torque while at the same time making it possible to perform non-magnetic modification through a simple process. [Means for solving the problem]

[0010] The inventors disclosed the invention of a stainless steel magnet in 2019 (Patent Document 4). Furthermore, as shown in Patent Document 5, based on their experience of changing the plate components of a magnetic denture attachment from a magnetic material to a stainless steel magnet and finding that the adhesive force increased by 50%, and noting that the resistivity of a stainless steel magnet is 72 μΩcm, more than twice the 32 μΩcm of the 3% silicon steel plate used as the magnetic material in IPM motors, the inventors considered changing the magnetic material of the rotor of an IPM motor to a stainless steel magnet. After much trial and error, they found that by changing the structure of Ni-based stainless steel from 100% austenite to one with 80% or more martensite to create a semi-hard magnetic material, and by adopting a stainless steel magnet with a saturation magnetization of 12,000 to 16,000 G, a coercive force of 80 to 300 Oe, a residual magnetism Br of 6,000 to 8,000 G, and a maximum energy product of 0.2 to 4 MGOe at room temperature, and by making specific areas of the rotor core non-magnetic through modification, they were able to increase the motor torque by 30% or more compared to a rotor whose main body material has not been modified to be non-magnetic with a magnetic material. Moreover, they confirmed that by heating the non-magnetic areas to 900°C or more using a laser or high-frequency heating method, the austenite phase can be restored and modified to be non-magnetic without changing the shape of the outer periphery.

[0011] <Rotor of encapsulated magnet type synchronous machine> (1) The rotor of the encapsulated magnet type synchronous machine of the present invention comprises a main body made of a stainless steel magnet and having an encapsulated portion consisting of gaps arranged axially symmetrically around the central axis of rotation, and a permanent magnet provided in the encapsulated portion. In the rotor, magnet end regions extending from each end of the permanent magnet to the outer circumferential edge of the rotor body are made of nonmagnetic parts. Alternatively, the magnet end outer circumferential edge region of the body, which is made up of a magnet end region extending from one end of one permanent magnet to the outer circumferential edge of the rotor body, a magnet end region extending from the other end of an adjacent permanent magnet to the outer circumferential edge of the rotor body, and a connecting region connecting the magnet ends, is made of nonmagnetic parts. The permanent magnets consist of rare earth bonded magnets that are injection molded within an envelope that has an aligning magnetic field applied to it.

[0012] (2) The rotor of the present invention is made of efficiently oriented permanent magnets (rare earth bonded magnets) and stainless steel magnet parts that are efficiently oriented and magnetized in the same way, which contributes to improving the performance of encapsulated magnet type synchronous machines. The reasons for this are thought to be as follows.

[0013] First, in the rotor of the present invention, as shown in Figure 4(b), there is a case where the non-magnetic part extends from the end of the permanent magnet stored in the internal portion to the outer peripheral end of the main body (referred to as the non-magnetic part of the magnet end region), and as shown in Figure 4(c), there is a case where the outer peripheral side region extending from the end of the permanent magnet stored in the internal portion to the outer peripheral end of the main body (rotor core) and extending from the end of another adjacent permanent magnet to the outer peripheral end of the main body is a non-magnetic part (referred to as the non-magnetic part of the magnet end outer peripheral side region). When an aligning magnetic field is applied to an inner encapsulation portion with such a non-magnetic outer peripheral region during injection molding, the aligning magnetic field flows from the inner magnetic pole portion of the permanent magnet to the outer magnetic pole portion, and then flows from the outer magnetic pole portion of the adjacent permanent magnet to the inner magnetic pole portion. However, if there were no nonmagnetic portion at the end of the magnet, a large leakage magnetic flux would flow directly from the inner magnetic pole to the outer magnetic pole of the permanent magnet, which would not contribute to the alignment of the rare earth anisotropic magnet powder, weakening the aligning magnetic field. Conversely, if there is a non-magnetic portion at the end of the magnet, the leakage flux is drastically reduced and the aligning magnetic field is strengthened. Also, if there is a non-magnetic portion at the outer peripheral region of the end of the magnet, the large leakage flux that flows directly from the inner magnetic pole to the outer magnetic pole of the permanent magnet is further reduced, so the aligning magnetic field becomes even stronger.

[0014] Conversely, the aligning magnetic field applied externally to the rotor during injection molding becomes distributed at high density within the rotor's internal cavity and in the stainless steel magnet section, greatly increasing the effective magnetic flux that contributes to the alignment of the rare earth anisotropic magnet powder. Therefore, the rare earth anisotropic bonded magnet of the present invention can be injection molded with an aligning magnetic field of 1 T or more acting on it.

[0015] Furthermore, when an aligning magnetic field of 1T or more is applied, the rare earth bonded magnet is molded in a saturated magnetized state. The saturated magnetized state is maintained even after injection molding is completed, so magnetization after injection molding (post-magnetization) may not be necessary. This is particularly effective in the case of rare earth anisotropic bonded magnets made from rare earth anisotropic magnet powder (such as Nd-Fe-B magnet powder), which is a difficult-to-align magnet powder that requires a magnetizing magnetic field of about 3T in the post-magnetization process.

[0016] At the same time, the stainless steel magnet material of the rotor is magnetized from its semi-hard magnetic properties to oriented saturation by the oriented magnetic field from the north pole to the south pole of the rare earth magnet, and becomes a permanent magnet, and the magnetic flux emanating from the rotor's magnetic poles increases by about 10% by changing the rotor's main body material from a magnetic material to a stainless steel magnet, which increases the motor torque by about 10%.

[0017] Furthermore, by demagnetizing the magnet end region that extends from the end (end face) of the permanent magnet, which is the different magnetic pole face, to the outer circumferential edge of the rotor body (as shown in FIG. 4(b)), or by demagnetizing the magnet end outer circumferential region consisting of the magnet end region that extends from the end (end face) of the permanent magnet, which is the different magnetic pole face, to the outer circumferential edge of the rotor body, another magnet end region that extends from the end (end face) of the other permanent magnet, which is the different magnetic pole face, to the outer circumferential edge of the rotor body, and a connecting region that connects these two magnet end regions (as shown in FIG. 4(c)), the magnetic flux can be increased by about 30%. This increases the motor torque by about 30%.

[0018] Of course, in the present invention, the permanent magnets contained in the rotor are bonded magnets, which has many advantages over embedding sintered magnets. For example, it is possible to reduce the use of rare and expensive rare earths. Furthermore, when using sintered magnets, such processing is not necessary. In addition, no processing waste is generated, so rare and expensive rare earths are not wasted.

[0019] On the other hand, when using sintered magnets, adhesive is required to fix the sintered magnet inside the containment part (slot) when inserting it into the containment part, which results in a non-magnetic gap between the magnet and the magnetic material of the rotor, increasing the magnetic resistance and impairing the flow of magnetic flux.In addition, the permanent magnet needs to be magnetized to saturation before being installed inside the containment part, which can cause problems such as collisions between the permanent magnet and the magnetic material of the rotor, resulting in damage. However, bonded magnets, which are integrally molded within the encapsulation portion, are naturally firmly fixed within the slot, so they do not have the drawbacks of sintered magnets.

[0020] Also, during the operation of a synchronous machine, large iron losses due to eddy currents can occur in the sintered magnet. As the rotational speed increases, the eddy current loss increases quadratically, and accordingly, the magnet heats up, the coercive force decreases, and finally, the magnet is demagnetized by the demagnetizing field from the electromagnet. On the other hand, since each magnet particle of the bonded magnet is insulated by a binder resin which is an insulator, the iron loss due to the generated eddy currents is extremely small. Therefore, a synchronous machine composed of a rotor incorporating the bonded magnet is efficient. Also, since each magnet particle of the bonded magnet is coated with a binder resin, it has high oxidation resistance without the need for surface treatment or the like.

[0021] <Embedded Magnet Type Synchronous Machine> (1) The present invention can be understood not only as the rotor described above but also as an embedded magnet type synchronous machine using the rotor. That is, the present invention may be an embedded magnet type synchronous machine including the rotor described above, a stator having a coil evenly disposed around the outer periphery of the rotor, and a yoke that forms a magnetic circuit on the outer peripheral side of the coil. Note that, as appropriate, the yoke includes teeth within the coil.

[0022] Basically, a synchronous machine generates a rotational force (magnet torque) based on the attractive force and repulsive force generated by the magnetic poles formed by the permanent magnets provided on the rotor and the rotating magnetic field formed around the outer periphery of the rotor by the stator. However, in the case of an embedded magnet type (embedded magnet type) synchronous machine, different from a surface magnet type synchronous machine, a difference is likely to occur between the inductance (Ld) generated in the magnetic poles and the inductance (Lq) generated between the magnetic poles. Therefore, the reluctance torque based on the attractive force often occurs 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 increase.

[0023] Therefore, it is preferable that the rotor according to the present invention also has salient poles that adjust the shape, arrangement, etc. of the permanent magnets (embedded portions) in the rotor, and generate a reluctance torque that acts in the same direction as the magnet torque generated by the magnetic poles, for example, between adjacent magnetic poles formed by the permanent magnets. Since the output of a synchronous machine is proportional to the rotation speed, it is desirable to increase the rotation speed. In the case of sintered Nd magnets, the faster they rotate, the more heat they generate, making it difficult to increase the rotation speed to 30,000 RPM or more. Therefore, this invention, which uses rare earth injection molded bonded magnets, is more suitable for synchronous machines with a rotation speed of 30,000 RPM or more.

[0024] <Manufacturing method for encapsulated magnet type synchronous machine> Furthermore, the present invention can be understood not only as the above-mentioned encapsulated magnet type synchronous machine and its rotor, but also as a manufacturing method for the rotor. That is, the present invention can be understood as a manufacturing method for a rotor of an encapsulated magnet type synchronous machine having a main body made of stainless steel magnets and having an encapsulated part consisting of gaps arranged axially symmetrically around the rotation center axis, and a permanent magnet provided in the encapsulated part, characterized in that it includes an injection molding process in which a molten mixture in which rare earth anisotropic magnet powder is dispersed in a molten binder resin is injected and filled into the encapsulated part having a non-magnetic part in the above-mentioned intermediate region or outer peripheral region in an aligning magnetic field to mold a rare earth anisotropic bonded magnet that becomes a permanent magnet. Effect of the Invention

[0025] According to the present invention, in an IPM motor having a rotation speed of 30,000 RPM or more, the motor torque can be increased by 30% or more, and the outer peripheral region of the rotor made of stainless steel magnet can be easily demagnetized by a simple process. [Brief description of the drawings]

[0026] [Figure 1] 1 is a cross-sectional view of a main portion of a synchronous motor according to the present invention; [Diagram 2] FIG. 2 is a plan view of the semi-hard magnetic material, the encapsulated portion, and the non-magnetic portion that constitute the rotor preform. [Diagram 3] FIG. 2 is a plan view of the stainless steel magnets, permanent magnets, and non-magnetic parts that make up the rotor. [Figure 4] 1A is a partial view of a rotor preform, showing (a) a punched material with an inner encapsulation portion formed therein, (b) a non-magnetic portion only in the magnet end region, and (c) a plan view showing the non-magnetic portion in the outer peripheral region of the magnet end. BEST MODE FOR CARRYING OUT THEINVENTION

[0027] The rotor of the encapsulated magnet synchronous machine of the present invention is A rotor body made of stainless steel magnets and having an even number of encapsulation portions each having an air gap arranged axially symmetrically around a central axis of rotation; An even number of permanent magnets provided in the inner container; A rotor of an internal magnet type synchronous machine comprising: a magnet end region extending from an end of the permanent magnet to an outer circumferential end of the rotor body is made of a non-magnetic portion; The permanent magnet is characterized in that it is made of a rare earth anisotropic bonded magnet that is injection molded within the inner container to which an aligning magnetic field is applied.

[0028] In addition, the rotor of the encapsulated magnet type synchronous machine is A rotor body made of stainless steel magnets and having an even number of encapsulation portions each having an air gap arranged axially symmetrically around a central axis of rotation; An even number of permanent magnets provided in the inner container; A rotor of an internal magnet type synchronous machine comprising: a magnet end outer circumferential side region including a magnet end region extending from one end of the permanent magnet to the outer circumferential edge of the rotor body, a magnet end region extending from the other end of another permanent magnet adjacent to the permanent magnet to the outer circumferential edge of the rotor body, and a connecting region connecting the magnet end regions, is made of a nonmagnetic portion; The permanent magnet is characterized in that it is made of a rare earth anisotropic bonded magnet that is injection molded within the inner container to which an aligning magnetic field is applied. Hereinafter, a detailed explanation will be given with reference to FIG. 1 to FIG.

[0029] <Rotor of encapsulated magnet type synchronous machine> (1) Main unit The rotor body 11 is made of stainless steel magnets 10, and although the material is not critical, it is preferably an iron-based material such as Cr-Ni stainless steel or Mn non-magnetic steel, which is a semi-hard magnetic material that is in a non-magnetic austenite phase at room temperature and becomes a magnetic martensite phase after cold working. The shape is usually a laminate of thin plates with insulating coating on both sides. This makes it possible to easily form a nonmagnetic portion by partial modification through local heating.

[0030] (2) Inner capsule The encapsulation portions 12, 121-126 of the rotor 11 are provided in the main body 11 and consist of gaps for disposing permanent magnets. There are at least two encapsulation portions 12, 121-126, each of which encapsulates a permanent magnet that serves as a magnetic pole, and these are usually arranged symmetrically around the central axis of rotation of the main body.

[0031] The shape of the inner packet part is a convex shape that is convex on the inner circumference so that a strong aligning magnetic field can be applied uniformly throughout the entire inner packet part, and is formed into a smooth curved shape. The shape of the inner encapsulation part is adjusted appropriately depending on the specifications of the synchronous machine. For example, in the case of six magnetic poles, the inner encapsulation part 12, 121-126 may be a radial inner encapsulation part (12, 121-126) that extends linearly from the center in the radial direction. It is also preferable that the inner encapsulation part has a uniform groove width. Conversely, it is preferable that there is no sudden change in shape or size that would cause the applied aligning magnetic field to concentrate locally.

[0032] Furthermore, the encapsulation section may be a multi-layered encapsulation section with multiple layers in the radial direction. A multi-layered encapsulation section can increase the reluctance torque. The number of layers in the multi-layered encapsulation section is not important, but two or three layers are preferable in terms of achieving both the characteristics and productivity of the synchronous machine.

[0033] In the present invention, the permanent magnet is made of an injection-molded rare earth bonded magnet (hereinafter referred to as a bonded magnet), so regardless of the shape of the contained part, the permanent magnet will basically conform to the shape of the contained part. However, since it is possible to injection mold the contained part with a spacer or the like interposed therebetween, the shape of the contained part and the shape of the permanent magnet may not match. There are two types of bonded magnets: isotropic and anisotropic, and it is preferable to use the anisotropic type. This eliminates variations in the rotor's magnetic field distribution and localized heat generation, enabling the rotor to rotate at high speeds and increasing the output of the IPM motor.

[0034] (3) Non-magnetic part The non-magnetic portions 14 are locations where the magnetic permeability is 1.2 or less. The non-magnetic portions 14, 141 to 146 are formed by modifying portions obtained by partially modifying the semi-hard magnetic material of the stainless steel magnets 10 that constitute the rotor body 11 before the semi-hard magnetic material is saturation magnetized. This makes it possible to make the magnetic circuit more efficient, and is expected to result in a 30% increase in motor torque.

[0035] The modification of the semi-hard magnetic material can be achieved by restoring the ferromagnetic martensite structure to a non-magnetic austenite structure. Such modification can be stably achieved by localized heating at 900°C or higher, irradiation with a laser or electron beam, high-frequency induction heating, etc.

[0036] The formation of the non-magnetic portion will be explained with reference to FIG. 4, which is a partial view of six magnetic poles. (a) Punched material forming the inner packet A rotor preparatory body (preparatory main body) 110 is produced by punching out a thin plate of a semi-hard magnetic material 111. The outer periphery of the rotor preparatory body (preparatory main body) is designated as an outer periphery end 111e. Each of inner packet part 121 and adjacent part 122 has two end faces (end parts), one end face being 121a and the other end faces being 121b and 122a, 122b. The region extending from end 121a of inner packet part 121 to outer circumferential edge 111e is referred to as magnet end region 121am. Similarly, the region extending from an end of the inner packet part to the outer circumferential edge will hereinafter be referred to as magnet end region.

[0037] (b) Non-magnetic part of the magnet end region The magnet end regions 121a, 121b, 122a, and 122b made of a semi-hard magnetic material are locally heated to change the martensite structure to an austenite structure, thereby forming the non-magnetic portions 141a, 141b, 142a, and 142b. The non-magnetic portions formed by this modification are formed at two locations, at both ends of each inner part.

[0038] (c) Non-magnetic area on the outer periphery of the magnet end Since one end 121a of the inner part 121 and the other end 122b of the inner part 122 are adjacent to each other, the three regions consisting of the magnet end region 121am of the inner part 121, the adjacent magnet end region 122b (numeral omitted in the figure) of the inner part 122, and the connecting region connecting the two magnet end regions are treated as the magnet end outer periphery side region and modified by a single local heating to form the non-magnetic portion 141. This method makes it possible to form one non-magnetic portion in one inner capsule part, thereby reducing the number of times local heating is performed by half.

[0039] The non-magnetic portion 14 according to the present invention is formed by heating and modifying the martensite structure in the outer peripheral region between adjacent permanent magnets (bonded magnets) so that a high aligning magnetic field is uniformly induced in the portion (encapsulated portions 121-126) where the bonded magnet is injection molded, to form a non-magnetic portion. This makes it possible to drastically reduce the leakage magnetic flux that flows directly from the inner magnetic pole to the outer magnetic pole via a specific part of the outer peripheral region of the end in the flow of the aligning magnetic field applied from outside the body, thereby strengthening the aligning magnetic field that contributes to the alignment. The non-magnetic part in Figure 4(c) is preferable to Figure 4(b) because it can reduce the leakage magnetic flux even more.

[0040] The non-magnetic portion is made of Cr-Ni stainless steel or the like, has excellent mechanical properties, and has only been modified by localized heating, so the precision at the time of manufacturing the rotor body is maintained, making it suitable for high-speed rotation of the rotor.

[0041] <Rare earth anisotropic bonded magnet> (1) Raw materials Rare earth anisotropic bonded magnets are basically made of rare earth anisotropic magnet powder and binder resin. The rare earth anisotropic magnet powder is not particularly limited in type, and examples include Nd-Fe-B magnet powder, Sm-Fe-N magnet powder, Sm-Co magnet powder, etc. These rare earth anisotropic magnet powders may be one type or multiple types.

[0042] The binder resin may be any known material including rubber. For example, it is preferable to use thermoplastic resins such as polyethylene, polypropylene, polyamide, liquid crystal polymer, and polyamide-imide. In addition, it is also possible to appropriately use thermosetting resins such as epoxy resin, netic resin, melamine resin, and polyurethane.

[0043] (2) Injection molding The rare earth anisotropic bonded magnet according to the present invention is formed by heating and melting pellets or the like made of the above-mentioned raw materials, injecting the molten mixture into an encapsulating part to which an aligning magnetic field is applied, and then cooling and solidifying the mixture. The conditions for injection molding are appropriately adjusted taking into consideration the characteristics of the raw materials, the filling amount, the cooling properties of the encapsulating part, etc. For example, the heating temperature during injection molding (the temperature of the molten mixture) is preferably lower than the Curie point of the rare earth anisotropic magnet powder.

[0044] The aligning magnetic field must be applied before the molten mixture solidifies, but it may be applied from the beginning of injection molding or in the middle of injection molding. For example, if a permanent magnet is used as the aligning magnetic field source, it may be applied from the beginning of injection molding, and if an electromagnet is used, it may be applied in the middle of injection molding. The application form of the aligning magnetic field (distribution of magnetic flux density formed in the rotor) is appropriately adjusted according to the shape of the encapsulation part and the specifications of the synchronous machine.

[0045] <Enclosed magnet type synchronous machines and their applications> The present invention is suitable for application to an internal magnet type synchronous machine (IPM motor) having a rotation speed of 30,000 RPM. Its applications include vehicle drive motors used in electric automobiles, hybrid vehicles, and railroad cars, and motors for home appliances used in air conditioners, refrigerators, washing machines, etc. However, it is not limited to the above applications. EXAMPLES

[0046] An embodiment of an internal magnet type synchronous machine of the present invention will be described with reference to Figs. FIG. 1 shows a cross-sectional view of a key portion of a synchronous motor SM, FIG. 2 shows a plan view of the semi-hard magnetic material, encapsulated portion, and non-magnetic portion that constitute the rotor preform, FIG. 3 shows a plan view of the stainless steel magnets, permanent magnets, and non-magnetic portions that constitute the rotor, and FIG. 4 is a partial view of the rotor preform of FIG. 3, showing (a) the punched material that forms the encapsulated portion, (b) the non-magnetic portion in the magnet end region, and (c) the non-magnetic portion in the outer circumferential region of the magnet end. The synchronous motor SM shown in FIG. 1 is a 6-pole, 18-throttle type. The stator S and the rotor 1 will be described in detail below.

[0047] (1) Stator As shown in FIG. 1, the stator S is made of laminated electromagnetic steel sheets and comprises an annular yoke Sa, teeth Sb protruding evenly toward the center from the yoke Sa, and slots Sc formed between adjacent teeth Sb. Each slot Sc houses an electromagnetic coil (not shown) that is wound around the teeth Sb. When inverter-controlled three-phase AC is supplied to each electromagnetic coil, a rotating magnetic field is generated in the stator S at a synchronous speed according to the frequency and number of poles.

[0048] (2) Spare rotor As shown in FIG. 2, the rotor spare body (spare main body) 110 is formed by laminating disc-shaped semi-hard magnetic material 111 having a central hole 151 and six internal portions 121-126 consisting of long grooves of equal width that penetrate the central hole 151 and have a curved (convex) shape toward the inner circumference and are arranged evenly and axially symmetrically around the center. By stacking this semi-hard magnetic material 111, a roughly cylindrical spare body 110 is formed extending in the direction of the central axis of rotation (perpendicular to the plane of the paper in Figure 2), with the internal portions 121-126 consisting of long grooves becoming penetrating internal portions extending in the same direction in which the permanent magnet M is injection molded, and the central hole 151 becoming a shaft hole 151 extending in the direction in which the shaft (not shown) of the synchronous motor SM is inserted.

[0049] The ends of the encapsulation part are modified parts 141-146 (non-magnetic parts) obtained by modifying the outer circumferential end of the spare body 110 made of a semi-hard magnetic material to a non-magnetic austenitic structure. This modification process was performed by localized heating, in which the outer circumferential region of the spare body 110, which is the part to be treated, is heated to 900°C or higher with a laser.

[0050] (2) Rotor body Within the encapsulation portion 12 (121-126) having the modified portions 141-146 on the outer periphery of both ends, permanent magnets M made of rare earth anisotropic bonded magnets were formed by injection molding in a magnetic field. Specifically, first, the spare body 110 is set in a magnetic field injection filling device (not shown), and an orienting magnetic field in which the polarity alternates between adjacent packet parts 12 is applied toward the packet parts 12 . Furthermore, at the same time as forming the permanent magnets M (121M to 126M), a preliminary body made of a semi-hard non-magnetic material was magnetized to saturation to form a stainless steel magnet. In this way, the rotor body 11 was produced.

[0051] That is, a molten mixture obtained by heating and melting pellets made of Nd-Fe-B anisotropic magnet powder, Sm-Fe-N magnet powder, and polyphenylene sulfide resin (binder resin) is injected and filled into these contained portions 12. After this, the molten mixture in contained portion 12 is solidified by cooling in a mold of a magnetic field injection filling device, and a permanent magnet M is formed integrally molded in contained portion 12. In this way, a rotor 1 was obtained that contains permanent magnets M curved on the inner circumference side in an annular and uniform manner.

[0052] In this embodiment, an aligning magnetic field was applied to the slot 12 from the start of filling the molten mixture to the end of filling. At this time, the aligning 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.

[0053] As a result, the magnetic particles in the permanent magnet M are not only oriented during injection molding in a magnetic field, but are also simultaneously magnetized, so that the permanent magnet M already exhibits a high magnetic flux density. For this reason, in this embodiment, there was no need to perform post-magnetization.

[0054] (3) Motor A shaft (not shown) is fitted into the shaft hole 19 of the rotor 1, which contains a permanent magnet M. The rotor 1 is rotatably disposed within the stator S. At this time, the gap formed between the outer peripheral end face of the rotor 1 and the inner end faces of the teeth Sb is set to be constant. This synchronous motor SM is obtained. When this synchronous motor SM is connected to an inverter-controlled power supply and a rotating magnetic field is generated in the stator S, the rotor 1 begins to rotate in synchronization with it.

[0055] In the synchronous motor SM, the inductance Lq1 in the q-axis direction, which is shifted by π / 2 (electrical angle) from the d-axis direction, is larger than the inductance Ld1 in the d-axis direction that passes through the center of the permanent magnet M. Therefore, in the synchronous motor SM1, not only the magnet torque Tm1 due to the permanent magnet M1, but also the reluctance torque Tr1 based on the inductance difference (Lq1-Ld1) is generated in the same direction as the magnet torque Tm1. Therefore, the synchronous motor SM1 exerts a larger output. Note that the definitions of the d-axis and the q-axis are the same in the following examples. [Industrial Applicability]

[0056] The motors can be widely used as vehicle drive motors for electric vehicles, hybrid vehicles, and railroad cars, motors for home appliances for air conditioners, refrigerators, washing machines, and the like, and drive motors for various robot devices. [Explanation of symbols]

[0057] SM: Synchronous motor (enclosed magnet type synchronous machine) 1: Rotor 10: Stainless steel magnet (plate), 12: Inner part, 14: Non-magnetic part, 15: Shaft M: Permanent magnet (rare earth anisotropic bonded magnet) d: Axial direction passing through the center of permanent magnet M q: Axial direction shifted by π / 2 (electrical angle) from d-axis direction 2: Stator Sa: Annular yoke, Sb: Teeth, Sc: Slot

[0058] 110: Spare rotor body (spare body) 111: semi-hard magnetic material, 121 to 126: encapsulated portion, 141 to 146: non-magnetic portion, 151: Shaft hole

[0059] 11: Rotor (main body) 10: Stainless steel magnet (stainless steel magnet part) 110: Outer edge of the main body 121M~126M: Permanent magnet 121Ma: One end of a permanent magnet 122Mb: other end of permanent magnet 141~146: Non-magnetic part 151: Shaft hole

[0060] 30: Semi-hard magnetic material with inner container punched out 111: Semi-hard magnetic material (spare body) 111e: Outer edge of spare body 121~122: Inner part 121a: One end of the inner packet part 121 121am: magnet end region of inner container 121 121b: the other end of the inner packet part 121 122a: One end of the inner packet part 122 122b: the other end of the inner packet part 122 30A: Non-magnetic part of the magnet end area 121~122: Inner part 141a: Non-magnetic portion obtained by modifying the magnet end region 121am 141b: Non-magnetic portion obtained by modifying the magnet end region 121bm (no reference number in the figure) 142a: Non-magnetic portion obtained by modifying the magnet end region 122am (no reference number in the figure) 142b: Non-magnetic portion obtained by modifying the magnet end region 122bm (no reference number in the figure) 30B: Non-magnetic portion of the outer peripheral region of the magnet end region 121~122: Inner part 141: outer peripheral region of the magnet end region (121am, 122bm and the connecting region between the two) Non-magnetic parts 142: Non-magnetic portion of the outer peripheral region of the magnet end region 146: Non-magnetic portion of the outer peripheral region of the magnet end region

Claims

1. A rotor of an internal magnet type synchronous machine comprising: a rotor body having an even number of internally contained portions each consisting of a stainless steel magnet and an even number of gaps arranged axially symmetrically around a central axis of rotation; and an even number of permanent magnets provided in the internally contained portions, a magnet end region extending from an end of the permanent magnet to an outer circumferential end of the rotor body is made of a non-magnetic portion; 1 is a perspective view of a rotor of an internal magnet type synchronous machine according to the present invention;

2. A rotor of an internal magnet type synchronous machine comprising: a rotor body having an even number of internally contained portions each consisting of a stainless steel magnet and an even number of gaps arranged axially symmetrically around a central axis of rotation; and an even number of permanent magnets provided in the internally contained portions, a magnet end outer circumferential side region including a magnet end region extending from one end of the permanent magnet to the outer circumferential edge of the rotor body, a magnet end region extending from the other end of another permanent magnet adjacent to the permanent magnet to the outer circumferential edge of the rotor body, and a connecting region connecting the magnet end regions, is made of a nonmagnetic portion; 1 is a perspective view of a rotor of an internal magnet type synchronous machine according to the present invention;

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