JP2017135857A - Manufacturing method for motor rotor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a motor rotor, by which coercive field strength is ensured with respect to a reverse magnetic field and a loss resulting from eddy current is reduced, the rotor having three magnetic slots for each magnetic pole.SOLUTION: A manufacturing method for a rotor motor comprises the step of: manufacturing a modified permanent magnet 1; dividing the modified permanent magnet 1 into three in a widthwise direction along a lengthwise direction, thereby producing a central separate magnet 2 and two outside separate magnets 3; and producing a motor rotor, which is a rotor 10 comprising three magnet slots (a central slot 11 and right and left slots 12, 13 with the central slot 11 between them) for one magnetic pole opening in the rotor 10, the central slot 11 being disposed on the further outer periphery side of the rotor 10 than the right and left slots 12, 13, by inserting the two outside separate magnets 3 into the central slot 11, inserting the outside separate magnets 3 into the right and left slots 12, 13 on the rotor outer periphery sides, and inserting the central separate magnets 2 into the right and left slots on the rotor central side.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method of manufacturing a magnet-embedded motor rotor.

  Among various motors including a brushless DC motor, a motor (IPM motor) having a permanent magnet embedded rotor in which a plurality of permanent magnets are embedded in a rotor core is well known. For example, the above-described IPM motor is used as a drive motor for a hybrid vehicle.

  By the way, a coil is formed in the stator teeth by concentrated winding or distributed winding, and a magnetic flux is generated by passing a current through the coil to generate a magnetic torque and a reluctance between the permanent magnet and the magnetic flux. Torque is generated.

  In the case of this distributed winding coil, the number of teeth per pole is larger than in the case of concentrated winding coils, and therefore the magnetic flux (or change in magnetic flux) entering the permanent magnet of the rotor from the teeth side when the rotor rotates. ) Is relatively continuous. Therefore, the change of the magnetic flux density at the time of rotor rotation is relatively small.

  On the other hand, in the case of the concentrated winding coil, the change in the magnetic flux density is relatively large, so the eddy current generated in the permanent magnet becomes a loss and reduces the driving efficiency of the motor. Furthermore, the permanent magnet generates heat due to the generation of eddy current, and irreversible thermal demagnetization is caused, so that the magnetic characteristics of the permanent magnet itself are deteriorated.

  Speaking of drive motors used in recent hybrid vehicles and electric vehicles, for example, the number of revolutions and the number of poles have been increased while the improvement in motor output performance has been pursued. Due to the increase or the like, the number of fluctuations per unit time of the magnetic field acting on the magnet is increased, and as a result, the eddy current is easily generated.

  The loss due to the eddy current reduces the driving efficiency of the motor, and the heat generation due to the eddy current leads to thermal demagnetization of the magnet, which reduces the motor performance and improves the durability of the motor. There is a problem that it leads to a decrease.

  In order to prevent the generation of eddy currents and the resulting induction of thermal demagnetization, in an IPM motor, a permanent magnet is formed from a plurality of divided magnets, and the divided magnets are bundled into a magnet slot. Measures to install are taken.

  In addition, the permanent magnet inserted and installed in the magnet slot has a coercive force by diffusing and infiltrating the modified alloy from the surface of the permanent magnet in order to cope with demagnetization due to the reverse magnetic field entering from the stator side. A device to raise is made.

  In addition to heavy rare earth elements such as Dy and Tb, this modified alloy includes alloys of heavy rare earth elements and light rare earth elements such as Nd, alloys of heavy rare earth elements and transition metal elements composed of Cu, Al, etc., light rare earth elements And transition metal element alloys are applied.

  When the modified alloy is diffused and penetrated from the surface of the permanent magnet, a concentration distribution is generally formed in which the concentration of the modified alloy gradually decreases from the surface of the permanent magnet toward the center.

  In this way, by dividing the permanent magnet in which the modified alloy is diffused and permeated, machining a plurality of divided magnets and inserting the plurality of divided magnets into one magnet slot ensures a coercive force against a reverse magnetic field. In addition, it is possible to manufacture a motor rotor with reduced loss due to eddy current.

  By the way, there are various forms of magnet slots per magnetic pole established in the rotor, one magnet slot having its longitudinal direction oriented in the circumferential direction of the rotor, and two magnet slots having their longitudinal directions. A configuration in which the direction is arranged in a substantially V shape with the direction directed to the radial direction of the rotor is common.

  Here, in Patent Document 1, a sintered magnet in which a heavy rare earth element is segregated at a grain boundary near the surface is perpendicular to the magnetization direction with respect to two magnet slots arranged in a substantially V shape. There is disclosed a permanent magnet motor in which two sintered magnet segments obtained by dividing a surface are arranged so that a surface with a relatively high concentration of heavy rare earth elements is located on the outer peripheral surface side of the rotor. Yes.

JP2011-229329A

  According to the permanent magnet motor described in Patent Document 1, two sintered magnet segments are arranged in an effective manner against a reverse magnetic field with respect to two magnet slots arranged in a substantially V shape. Is done.

  By the way, the present inventors are not two magnet slots arranged in a substantially V shape in this way, but three magnet slots per one magnetic pole, which are located in the center and in the circumferential direction of the rotor. A central slot in which the longitudinal direction of the slot is oriented, and two left and right slots sandwiching the central slot, the left and right slots both oriented in the radial direction of the rotor. Thus, a motor rotor has been proposed in which the coercive force of a permanent magnet is ensured against a reverse magnetic field and the loss due to eddy current is reduced.

  The present invention has been made in view of the above-described problems, and relates to a rotor having three magnet slots per magnetic pole, which ensures coercivity of a permanent magnet against a reverse magnetic field and is caused by eddy currents. An object of the present invention is to provide a method for manufacturing a rotor for a motor with reduced loss.

  In order to achieve the above object, according to the method of manufacturing a rotor for a motor according to the present invention, a modified alloy is diffused and penetrated from the surface of a rectangular parallelepiped permanent magnet, and the concentration of the modified alloy gradually decreases from the surface of the permanent magnet toward the inside. A first step of manufacturing the modified permanent magnet, wherein the modified permanent magnet is divided into three in the width direction along the longitudinal direction to produce a centrally divided magnet and two outer divided magnets; The second step of manufacturing the two central divided magnets and the four outer divided magnets by dividing the two modified permanent magnets, three magnets per magnetic pole established in the rotor A central slot located in the center and oriented in the longitudinal direction of the slot in the circumferential direction of the rotor, and two left and right slots sandwiching the central slot, both in the radial direction of the rotor Longitudinal direction Left and right slots facing each other, with respect to the rotor in which the central slot is disposed on the outer peripheral side of the rotor as compared to the left and right slots, the two outer divided magnets are inserted into the central slot, This comprises a third step of manufacturing a motor rotor by inserting the outer divided magnet into the rotor outer peripheral side of each of the left and right slots and inserting the central divided magnet into the rotor central side of each of the left and right slots.

  The method for manufacturing a rotor for a motor according to the present invention is such that a divided magnet formed by dividing a permanent magnet in which a modified alloy is diffused and permeated into three slots for a magnet per magnetic pole is preferably disposed. It is a method of manufacturing.

  In the first step, the modified alloy is diffused and infiltrated from the surface of the rectangular parallelepiped permanent magnet, and a modified permanent magnet in which the concentration of the modified alloy gradually decreases from the surface of the permanent magnet toward the center is manufactured.

  Here, a rare earth magnet etc. can be mentioned as a permanent magnet.

  In addition to steel sheet laminates made by laminating electromagnetic steel sheets, the rotor is a magnetic material in which soft magnetic metal powders such as iron and iron-silicon alloys and soft magnetic metal oxide powders are coated with a resin binder such as silicone resin. It is formed from a green compact made of powder.

  Furthermore, the modified alloys that are diffused and penetrated from the surface of the permanent magnet include heavy rare earth elements such as Dy and Tb, alloys of heavy rare earth elements and light rare earth elements, alloys of heavy rare earth elements and transition metal elements, and light rare earth elements. And transition metal element alloys are applied.

  In contrast to the modified permanent magnet manufactured in the first step, in the second step, the modified permanent magnet is divided into three in the width direction along the longitudinal direction, and a central divided magnet and two outer divided magnets are formed. Two centrally divided magnets and four outer divided magnets are manufactured by manufacturing and performing this on two modified permanent magnets.

  Here, the rotor has a plurality of magnetic poles, and three magnet slots are opened corresponding to the magnetic poles. Therefore, in the second step, two central divided magnets and four outer divided magnets are prepared for each magnetic pole.

  When the permanent magnet after modification is divided into three in the width direction along its longitudinal direction, the central divided magnet having a rectangular cross section has two surfaces with the modified alloy diffused and infiltrated, while Since the outer divided magnet has three surfaces on which the modified alloy is diffused and permeated, the central divided magnet has a relatively high concentration region of the modified alloy, and the outer divided magnet has a modified alloy concentration. High areas are relatively large. Further, the outer corners of the outer divided magnet are portions where the modified alloy concentration is high and the coercive force is particularly high because the modified alloy diffuses from the two outer surfaces.

  Next, in the third step, a motor rotor is manufactured by appropriately disposing a central divided magnet and an outer divided magnet in each of three magnet slots per magnetic pole provided in the rotor.

  Here, the three slots for magnets are a central slot located in the center and the longitudinal direction of the slot faces the circumferential direction of the rotor, and two left and right slots sandwiching the central slot, both in the radial direction of the rotor. And left and right slots in which the longitudinal direction of the slot faces. The central slot is disposed on the outer peripheral side of the rotor as compared with the left and right slots.

  In other words, the central slot is arranged at the center position of the two left and right slots having a substantially V shape and on the outer peripheral side (stator side) of the rotor.

  Here, the “circumferential direction of the rotor” means that the longitudinal direction of the central slot of the rectangular shape in plan view is oriented in a direction perpendicular to an arbitrary radius of the rotor, and is disposed outside the rotor. This means that the longitudinal direction of the slot faces the end face of the stator teeth.

  Since the central slot is located on the stator side as compared to the left and right slots, the reverse magnetic field incident from the stator side is also relatively large, so the central slot has two regions with a high concentration of the modified alloy. Insert the outer split magnet. At this time, since the corner portion of the central slot has a large reverse magnetic field, the corner portion having a high modified alloy concentration in the outer divided magnet is inserted so as to be positioned at the corner portion of this slot. That is, the outer divided magnets are combined in a direction in which the cut surfaces of the outer divided magnet and the central divided magnet are matched.

  On the other hand, among the left and right slots, the rotor outer peripheral side has a relatively large reverse magnetic field incident from the stator as compared with the rotor central side. Insert an outer divided magnet with more area. Then, a centrally divided magnet with many regions having a low concentration of the modified alloy is inserted into the center side of the rotor in the left and right slots.

  Thus, according to the method for manufacturing a rotor for a motor of the present invention, two modified permanent magnets are divided into three in the width direction along the longitudinal direction of the rotor having three magnet slots per magnetic pole. The number of split magnets (six) into which the permanent magnets after splitting are divided and the number of split magnets to be inserted into the magnet slots by making two central split magnets and four outer split magnets (Six) are arranged, and these six divided magnets can be optimally arranged in each magnet slot.

  In a preferred embodiment of the method for manufacturing a rotor for a motor according to the present invention, the second step is a step of forming a chamfered portion at a corner portion of the outer divided magnet on the central divided magnet side, or The central divided magnet has at least one of steps of forming chamfered portions at two corners on the left and right outer divided magnets.

  In the outer divided magnet, a chamfered portion is formed at the corner portion on the center divided magnet side, and in the central divided magnet, a chamfered portion is formed at the two corner portions on the left and right outer divided magnet sides. The discrimination between the magnet and the outer divided magnet is easy and clear. That is, when the chamfered portion is formed on the outer divided magnet, there is a chamfer at one location on the central divided magnet side, and the central divided magnet has no chamfered portion or two chamfered portions. The magnet can be identified. As a result, it is ensured that an appropriate divided magnet is inserted into an appropriate position when being inserted into the magnet slot.

  As can be understood from the above description, according to the method for manufacturing a motor rotor of the present invention, a permanent magnet in which a modified alloy is diffused and penetrated into three magnet slots per magnetic pole is divided into three. In the rotor having three magnet slots per magnetic pole, the coercive force of the permanent magnet against the reverse magnetic field is ensured and the eddy current is generated. A rotor for a motor with reduced loss can be efficiently manufactured.

It is the schematic diagram explaining the 1st step of Embodiment 1 of the manufacturing method of the rotor for motors of this invention. It is the schematic diagram explaining the 2nd step of Embodiment 1 of a manufacturing method. It is the schematic diagram explaining the 3rd step of Embodiment 1 of the manufacturing method. It is the schematic diagram explaining the 2nd step of Embodiment 2 of the manufacturing method of the rotor for motors of this invention. It is the schematic diagram explaining the 3rd step of Embodiment 2 of the manufacturing method.

  Embodiments of a method for manufacturing a rotor for a motor according to the present invention will be described below with reference to the drawings. The rotors shown in FIGS. 3 and 5 are shown by extracting only the area corresponding to one magnetic pole for the sake of easy explanation. However, in the entire rotor, a divided magnet is provided for a magnet slot having a desired number of magnetic poles. Of course, it is inserted and installed.

(Embodiment 1 of manufacturing method of motor rotor)
1 to 3 are flowcharts of the embodiment of the method for manufacturing a motor rotor of the present invention in that order. More specifically, FIG. 1 is a schematic diagram illustrating a first step of the first embodiment of the method for manufacturing a rotor for a motor of the present invention, and FIG. 2 is a second view of the first embodiment of the manufacturing method. FIG. 3 is a schematic diagram illustrating the third step of the first embodiment of the manufacturing method.

  First, the magnet raw material is strip cast, pulverized to produce magnetic powder, and sintered in a magnetic field and then sintered to produce a permanent magnet. As shown in FIG. 1, the concentration of the modified alloy gradually decreases from the surface of the permanent magnet toward the center by diffusing and infiltrating the modified alloy from the surface of the permanent magnet. The modified permanent magnet 1 is manufactured (first step).

  In FIG. 1, the outside of the cross section is a high concentration region A1 of the modified alloy, the inside thereof is a medium concentration region A2 of the modified alloy, and the center side of the cross section is the low concentration region A3 of the modified alloy. Note that there are various methods for determining such a density region, and it may be divided into four or more appropriate regions.

  Here, examples of the permanent magnet include a rare earth magnet, a ferrite magnet, and an alnico magnet. As the rare earth magnet, a ternary neodymium magnet obtained by adding iron and boron to neodymium, and a two-component system composed of samarium and cobalt. Examples include samarium cobalt magnets made of alloys.

  In addition to the heavy rare earth elements such as Dy and Tb, the modified alloys diffused and penetrated from the surface of the permanent magnet include alloys of heavy rare earth elements and light rare earth elements, alloys of heavy rare earth elements and transition metal elements, and light rare earth elements. And transition metal element alloys are applied.

  These light rare earth elements include Nd and Pr, and transition metal elements include Cu, Mn, In, Zn, Al, Ag, Ga, and Fe. These alloys include Nd-Cu alloys, Pr- There are Cu alloy, Nd-Pr-Cu alloy, Nd-Al alloy, Pr-Al alloy, Nd-Pr-Al alloy and so on.

  Next, as shown in FIG. 2, the modified permanent magnet 1 manufactured in the first step is divided into three in the width direction along the longitudinal direction, and the central divided magnet 2 and the two outer divided magnets. 3 is produced.

  Then, by performing this on the two modified permanent magnets 1, two central divided magnets 2 and four outer divided magnets 3 are manufactured (second step).

  Here, as a method of dividing the modified permanent magnet 1, there is a method of dividing by splitting in addition to cutting by a cutter.

  Next, as shown in FIG. 3, in the third step, appropriate divided magnets are inserted into the three magnet slots 11, 12, 13 per magnetic pole established in the rotor 10.

  First, the rotor 10 is composed of a steel plate laminate in which electromagnetic steel plates are laminated to a desired height along the rotor axial direction, and a slot for a rotating shaft shaft is opened at the center 10b, and an end region thereof. The three magnetic slots 11, 12, and 13 per one magnetic pole are opened in the circumferential direction by a predetermined number of magnetic poles, and the whole is generally configured. In addition, the rotor 10 includes iron, iron-silicon alloy, iron-nitrogen alloy, iron-nickel alloy, iron-carbon alloy, iron-boron alloy, iron-cobalt in addition to the illustrated steel plate laminate. Magnets in which soft magnetic metal powders such as iron alloys, iron-phosphorus alloys, iron-nickel-cobalt alloys and iron-aluminum-silicon alloys, or soft magnetic metal oxide powders are coated with a resin binder such as silicone resin You may comprise from the compacting body which consists of powder.

  The three magnet slots 11, 12, and 13 are arranged in such a manner that the central slot 11 is located in the center and the longitudinal direction of the slot faces the circumferential direction (L1 direction) of the rotor 10, and the central slot 11 is sandwiched between the two slots. The left and right slots are composed of a left slot 12 and a right slot 13, both of which are oriented in the radial direction (L2 direction) of the rotor 10.

  Further, the central slot 11 is disposed on the outer periphery 10 a side of the rotor 10 as compared with the left slot 12 and the right slot 13.

  As for the method of inserting the divided magnets into the slots, two outer divided magnets 3 are inserted into the central slot 11, and the outer divided magnets 3 are inserted into the outer peripheral sides of the respective rotors for the left slot 12 and the right slot 13. Insert the central divided magnet 2 into the center of each rotor.

  Since the central slot 11 is located on the stator side (not shown) as compared with the left slot 12 and the right slot 13, the reverse magnetic field incident from the stator side is also relatively larger than that of the left slot 12 and the right slot 13. Accordingly, the two outer divided magnets 3 having a high concentration region A1 of the modified alloy are inserted into the central slot 11.

  On the other hand, of the left slot 12 and the right slot 13, the rotor outer peripheral side has a relatively large reverse magnetic field incident from a stator (not shown) as compared with the rotor center side. The outer divided magnet 3 having a high concentration region A1 of the modified alloy is inserted on the rotor outer peripheral side. Then, the central divided magnet 2 having a large amount of the low concentration region A1 of the modified alloy is inserted in the rotor central side of the left slot 12 and the right slot 13.

  Thus, according to the method for manufacturing the motor rotor shown in the figure, two post-reform permanent permanents are provided for the rotor 10 having three magnet slots (central slot 11, left slot 12, and right slot 13) per magnetic pole. The magnet 1 is divided into three along the longitudinal direction, and two central divided magnets 2 and four outer divided magnets 3 are manufactured. The number of divided magnets to be inserted into the slots is uniform, and these six divided magnets can be optimally arranged in each magnet slot.

(Embodiment 2 of manufacturing method of motor rotor)
Next, a second embodiment of the manufacturing method will be described. In the second embodiment of the manufacturing method, the first step is the same as that of the first embodiment of the manufacturing method, and thus the description thereof is omitted.

  As in the first embodiment of the manufacturing method, as shown in FIG. 2, after the modified permanent magnet 1 is divided into three along the longitudinal direction thereof, the central divided magnet 2 and the two outer divided magnets 3 are manufactured. 4, the outer divided magnet 3 has a chamfered portion 3 a at the corner portion on the center divided magnet side, and the center divided magnet has a chamfered portion on the two corner portions on the left and right outer divided magnet sides. 2a is formed (second step).

  Here, as the chamfering method described above, there are C chamfering and R chamfering, either by forming a groove along the planned dividing line and then dividing it, or after dividing and chamfering by machining. There may be.

  When these chamfered portions 2a and 3a become too large, the demagnetizing field becomes large. Therefore, when the height of each divided magnet is t and the chamfer width is s, s / t is less than 0.3. It is desirable to adjust the size of the chamfered portions 2a and 3a.

  Next, as shown in FIG. 5, in the third step, appropriate divided magnets are inserted into the three magnet slots 11, 12, and 13 per magnetic pole established in the rotor 10.

  When the outer divided magnet 3 is inserted into the central slot 11 and the central divided magnet 2 and the outer divided magnet 3 are inserted into the left slot 12 and the right slot 13, two chamfered portions 2a are formed in the central divided magnet 2. Since the chamfered portion 3a is formed in one place on the outer divided magnet 3, the central divided magnet 2 and the outer divided magnet 3 can be easily and clearly distinguished from each other, and the central slot 11, the left slot 12, and the right slot 13 can be distinguished. It is ensured that an appropriate segmented magnet is inserted into an appropriate position when inserting the magnet.

(Analysis and results for verifying that the arrangement of the three slots for magnets in the manufacturing method of the present invention is the optimum configuration)
In order to verify that the arrangement form of the three magnet slots in the manufacturing method of the present invention is the optimum form, the present inventors have conducted an analysis for obtaining a reverse magnetic field in the magnet slot. The reverse magnetic field here is the maximum reverse magnetic field under the maximum torque condition in each element.

  Table 1 below shows the reverse magnetic field in a size obtained by dividing the manufactured modified permanent magnet into three parts in the width direction along the longitudinal direction and further dividing into five parts at equal intervals in the longitudinal direction.

[Table 1]

  From Table 1, there is a possibility that the magnet is greatly demagnetized by the reverse magnetic field on the rotor center side of the left and right slots. On the other hand, according to the arrangement form of the three slots for magnets in the present invention, the coercive force is sufficiently high on the rotor center side, so that the optimum divided magnet arrangement is difficult to demagnetize.

  Further, according to the manufacturing method of the present invention, the modified permanent magnet is divided into three along the longitudinal direction thereof, so that the required size of the magnet can be easily obtained, and finish polishing on the cut surface can be eliminated.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Permanent magnet after modification | reformation, 2 ... Center division magnet, 3 ... Outer division magnet, 2a, 3a ... Chamfer part, 10 ... Rotor, 10a ... Outer periphery, 10b ... Center, 11 ... Center slot, 12 ... Left slot, 13 ... right slot, A1 ... high concentration region of the modified alloy, A2 ... medium concentration region of the modified alloy, A3 ... low concentration region of the modified alloy, L1 ... circumferential direction, L2 ... radial direction

Claims (2)

A first step of diffusing and infiltrating the modified alloy from the surface of the rectangular parallelepiped permanent magnet, and producing a modified permanent magnet in which the concentration of the modified alloy gradually decreases from the surface of the permanent magnet toward the inside;
The modified permanent magnet is divided into three in the width direction along the longitudinal direction to produce a center divided magnet and two outer divided magnets, and the three divisions are performed on the two modified permanent magnets. A second step of fabricating the two central split magnets and the four outer split magnets;
Three slots for one magnet per magnetic pole provided in the rotor, the central slot located in the center and facing the longitudinal direction of the slot in the circumferential direction of the rotor, and the two left and right slots sandwiching the central slot A rotor having left and right slots, both of which are longitudinally oriented in the radial direction of the rotor, the central slot being disposed on the outer peripheral side of the rotor as compared to the left and right slots. On the other hand, the two outer divided magnets are inserted into the central slot, the outer divided magnets are inserted into the rotor outer circumferences of the left and right slots, and the central divided magnets are inserted into the rotor central sides of the left and right slots. A method for manufacturing a motor rotor, comprising a third step of manufacturing a motor rotor. The second step includes
A step of forming a chamfered portion at a corner portion of the outer divided magnet on the central divided magnet side, or
Forming chamfered portions at two corners on the left and right outer divided magnets in the central divided magnet;
The manufacturing method of the rotor for motors of Claim 1 which has at least one of these.

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