JP2013165625A - Method of manufacturing rotor for ipm motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a rotor for an IPM motor capable of preventing the generation of eddy current loss at least caused by tight adhesion between divided magnets.SOLUTION: Provided is a method of manufacturing a rotor 100 for an IPM motor in which two divided magnets 4 whose planar shape is rectangular are buried in a slot 2 for a magnet. The planar shape of the slot 2 for a magnet is such a shape that a rectangle having a long side and a short side and a convex shape protruding outside the rectangle are combined. When a length of the long side of the slot 2 for a magnet is defined as t1, and a length of a long side of the divided magnet 4 corresponding to the long side of the slot 2 for a magnet is defined as t2, a relation of t1>2t2 is satisfied. The divided magnets 4 are freely movable in a rectangular region in the slot 2 for a magnet. The method includes the steps of: preparing a rotor core 10 and the divided magnets 4; and arranging the two divided magnets 4 in the slot 2 for a magnet in an attitude that a gap G is provided therebetween, and injecting a mold resin material 5 into the gap G to fix the divided magnets 4 by the mold resin in an attitude that the divided magnets 4 and 4 are not contacted with each other.

Description

  The present invention relates to a method of manufacturing a rotor for an IPM motor with a built-in magnet.

  Among various motors including a brushless DC motor, a motor (hereinafter referred to as an 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 reduces the thermal demagnetization of the magnet, which reduces the motor performance and reduces the durability of the motor. The problem that it leads to is generated.

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

  Here, with reference to FIGS. 8 and 9, an example of a method for fixing the divided magnets in the magnet slots provided in the conventional rotor core will be outlined.

  FIG. 8 is a plan view of the rotor core RC constituting the rotor for the IPM motor. The rotor core RC is configured by laminating electromagnetic steel plates to a desired height, for example, and a rotary shaft shaft slot SSL is opened in the center in the rotor axial direction. Two magnet slots SL opened in a V shape form one set, and a plurality of sets (a radix corresponding to the magnetic pole) are provided in the circumferential direction.

  FIG. 9a is an enlarged plan view of the magnet slot SL. The illustrated magnet slot SL includes a rectangular area SL1 having a long side and a short side at the center, and two short sides thereof. It has a planar shape consisting of convex regions SL2 and SL3 that are convex outward.

  The shape of the convex regions SL2 and SL3 is such that leakage flux that can be generated from the end of the permanent magnet can be reduced as much as possible when the permanent magnet is fixed in the magnet slot SL. . As described above, the convex regions SL2 and SL3 not only suppress the leakage magnetic flux from the permanent magnet, but also insert the mold resin material for fixing the magnet after the permanent magnet is inserted into the magnet slot SL. It also serves as an injection site for injection into the SL. That is, as shown in FIG. 9b, after the two divided magnets M and M are inserted into the rectangular region SL1 of the magnet slot SL, the molding resin material R is set with the convex regions SL2 and SL3 as injection starting points. Since the injected mold resin material R flows into the rectangular region SL1 from the convex regions SL2 and SL3 (Y direction), it is fixed in the slot with the two divided magnets M and M in close contact with each other. May be.

  However, since the split magnets M and M are fixed in the magnet slot SL in a manner as shown in FIG. 9b, the two split magnets M and M are inherently reduced in order to reduce the eddy current loss of one permanent magnet. Despite being divided into M, when the divided magnets M and M are brought into close contact with each other, both are brought into a conductive state, resulting in an increase in eddy current loss.

  Furthermore, the closely divided magnets M and M are in close contact with either one of the two long sides in the rectangular region SL1 constituting the magnet slot SL, and between the split magnets M and M and the rotor core RC. , The eddy current loss further increases.

  Here, in Patent Document 1, when two divided magnets are inserted into a magnet slot having a rectangular planar shape, a foamed resin sheet is interposed between them, and the sheet is thermally expanded in the magnet slot. Thus, a technique for fixing the divided magnets in the magnet slots is disclosed.

  According to this method, the split magnet can be firmly fixed in the magnet slot, and therefore, it is possible to suppress the split magnet from rattling due to vibration and the occurrence of cracks and chips. However, when the sheet is heated in the magnet slot, the divided magnets are also heated, which may affect the magnetic characteristics thereof, and thus is not a preferable method. In addition, since a foamed resin sheet is used, the manufacturing cost is higher than injecting a conventional mold resin, and further, a step of interposing the foamed resin sheet and a step of heat-treating it are required. Manufacturing man-hours also increase, which can significantly reduce manufacturing efficiency.

JP 2010-141989

  The present invention has been made in view of the above-described problems, and improves the conventional method of fixing a divided magnet by injecting a mold resin material into a slot for a magnet without reducing the production efficiency. An object of the present invention is to provide a method of manufacturing a rotor for an IPM motor capable of eliminating the occurrence of eddy current loss caused by at least the divided magnets closely contacting each other without increasing the manufacturing cost.

  In order to achieve the above object, a method for manufacturing a rotor for an IPM motor according to the present invention includes a rectangular slot having two planar shapes each having a length in the rotor axis direction in a magnet slot provided in a direction along the rotor axis. A method of manufacturing a rotor for an IPM motor in which a magnet is embedded, wherein the planar shape of the slot for a magnet is a combination of a rectangle having a long side and a short side and a convex shape protruding outward from each of the two short sides. When the length of the long side of the magnet slot is t1, and the length of the long side of the divided magnet corresponding to the long side of the two divided magnets is t2, t1 First, a rotor core having a slot for magnets and a split magnet are prepared, the two split magnets being movable within a rectangular area of the magnet slots, and having a relationship of> 2t2. Step, two split magnets in the magnet slot Place in a position with a gap between them, inject mold resin material for fixing the divided magnet into the gap, and mold the two divided magnets in the magnet slot in a position where at least the divided magnets do not contact each other This consists of a second step of fixing with resin.

  The method for manufacturing a rotor for an IPM motor according to the present invention has a rectangular shape in which two convex regions for suppressing leakage magnetic flux and two divided magnets are inserted between them as in the conventional magnet slot. And two divided magnets are inserted into the rectangular area of the magnet slot in a posture with a gap between them, or the two divided magnets are inserted into the magnet slot. After being inserted into the gap, a gap is formed between the two, and then a mold resin material for fixing the divided magnet is injected into the gap. The mold resin material injected into the gap first fills the gap and presses both divided magnets against the opposing short sides of the rectangular area, and the injected mold resin material fills other parts of the rectangular area. Furthermore, it flows so as to fill two convex regions. As a result, at least the divided magnets can be fixed in the magnet slot without contacting each other, and an increase in eddy current loss that can occur when the divided magnets are in close contact with each other and in a conductive state is effectively suppressed. be able to.

  In addition, as described above, since it is essential to provide a gap between the two divided magnets, the length of the long side in the region where the planar shape constituting the magnet slot is a rectangular region is t1, Among the divided magnets, when the length of the long side of the divided magnet corresponding to the long side is t2, the lengths of both long sides are set so as to have a relationship of t1> 2t2.

  Here, the planar shape of the divided magnets arranged in the rectangular region where the planar shape constituting the magnet slot may be either rectangular (rectangular) or square, but the mold resin material injected into the gap In the split magnet, the length of the side corresponding to the short side of the rectangular region of the magnet slot is the short side of the rectangular region. It is set to be shorter than the side length.

  Further, the applied divided magnet includes a rare earth magnet, a ferrite magnet, an alnico magnet, and the like. As the rare earth magnet, a ternary neodymium magnet in which iron and boron are added to neodymium, samarium and cobalt are used. A samarium cobalt magnet made of a binary alloy can be used.

  The rotor core that constitutes the rotor is not only a steel plate laminate formed by laminating electromagnetic steel plates, but also a soft magnetic metal powder such as iron, iron-silicon alloy, or a soft magnetic metal oxide powder is a resin binder such as a silicone resin. It may be a green compact formed of a coated magnetic powder or the like.

  According to the method for manufacturing a rotor for an IPM motor of the present invention described above, a conventional general mold resin material is injected without interposing other members between two divided magnets as in the method disclosed in Patent Document 1. However, since the split magnets are fixed by an extremely simple process improvement of changing the injection location, the manufacturing cost is not increased at all.

  In the present invention, two component magnets are inserted and fixed in the magnet slot. However, in the present invention, three or more segmented magnets are inserted and fixed in the magnet slot. It does not exclude anything to do. For example, when three divided magnets are used, when the length of the long side of the magnet slot is t1, and among the three divided magnets, the length of the long side of the divided magnet corresponding to the long side is t2. In addition, a configuration change such that t1> 3t2 has a relationship, a gap is formed between each of the three divided magnets (in this case, two gaps are formed), and a mold resin material is injected into these two gaps However, such a change in the configuration is included in the manufacturing method of the present invention described above.

  In a preferred embodiment of the method for manufacturing an IPM motor rotor according to the present invention, a convex portion is provided in the middle of the long side of the magnet slot, and the planar shape is 2 in a rectangular region. The dimension of the convex part is set so that the convex part wraps around the long side of each of the two split magnets when there are two split magnets, and the mold resin material injected into the gap in the second step is After the gap is filled, the gap passes between the long side of the divided magnet and the long side of the magnet slot through the convex portion to fill this gap.

  According to the manufacturing method of the present embodiment, of the magnet slots, convex portions having dimensions that straddle the two divided magnets are respectively provided in the middle positions of the two long sides of the rectangular region. Thus, the mold resin material injected into the gap between the divided magnets flows into the two convex portions after filling the gap, and flows along the long sides of the two divided magnets through the convex portions. Become. For this reason, the two split magnets maintain a posture separated from each other by the mold resin material, and both the split magnets are not in close contact with the long side constituting the rectangular region of the magnet slot, and the mold resin In-slot fixation for the magnet is achieved with a posture separated through the material.

  Accordingly, the two divided magnets are fixed in the magnet slots without contacting the divided magnets and without contacting the wall surfaces corresponding to the long sides of the divided magnets and the magnet slots. Are brought into close contact with each other, and an increase in eddy current loss due to close contact between the split magnets and the wall surfaces of the magnet slots can be effectively suppressed.

  Here, although the planar shape of the convex portion is not particularly limited, by applying a shape form such as a triangle, a semi-elliptical shape, a semi-circular shape, the mold resin material flowing out from the gap between the divided magnets is convex. It is preferable because it can be easily guided to the other regions and can easily flow to other regions.

  As can be understood from the above explanation, according to the method for manufacturing a rotor for an IPM motor of the present invention, two divided magnets are arranged in a magnet slot in a posture in which a gap is provided between the two magnets. An eddy current that can be generated in a conductive state by injecting a mold resin material for fixing a split magnet and fixing two split magnets in the magnet slot with a mold resin so that at least the split magnets do not contact each other The increase in loss can be effectively eliminated.

(A) is the figure explaining the 1st step of the manufacturing method of this invention, Comprising: It is a top view of the prepared rotor core, (b) is a bb arrow line view of (a). It is the top view to which the slot for magnets was expanded. It is a figure explaining the 1st step of a manufacturing method, Comprising: It is a perspective view of two division magnets prepared. (A) is the figure explaining the 2nd step of the manufacturing method, (b) is the figure which expanded the inside of the slot for magnets. (A) is the figure explaining the 2nd step of the manufacturing method following FIG. 4, (b) is a top view of the manufactured rotor. (A) is the top view which showed other embodiment of the slot for magnets with two division magnets, (b) is the figure explaining the flow of the mold resin material inject | poured into the clearance gap between division magnets. . (A), (b) is a top view of further another embodiment of the slot for magnets. It is a top view of the rotor core used with the conventional manufacturing method. (A) is the top view which expanded the slot for magnets, (b) is the figure explaining the flow of the mold resin material inject | poured in the slot for magnets.

  Embodiments of a method for manufacturing a rotor for an IPM motor according to the present invention will be described below with reference to the drawings. In the illustrated example, one magnetic pole is formed by two permanent magnets arranged in a substantially V shape. However, one magnetic pole is in a posture in which its longitudinal direction is directly opposed to the stator side. Of course, the form which a permanent magnet comprises may be sufficient.

(Embodiment of manufacturing method and embodiment 1 of slot for magnet)
1 to 5 are flowcharts of the method for manufacturing the rotor for the IPM motor of the present invention in that order. More specifically, FIG. 1a is a diagram illustrating the first step of the manufacturing method of the present invention, which is a plan view of a prepared rotor core, and FIG. 1b is a view taken along the line bb in FIG. 1a. FIG. 2 is an enlarged plan view of the magnet slot. FIG. 3 is a diagram illustrating a first step of the manufacturing method, and is a perspective view of two divided magnets to be prepared. FIG. 4A is a diagram illustrating a second step of the manufacturing method, and FIG. FIG. 4 is an enlarged view of the inside of a magnet slot. FIG. 5a is a view for explaining a second step of the manufacturing method subsequent to FIG. 4, and FIG. 5b is a plan view of the manufactured rotor.

  The illustrated rotor core 10 is composed of a steel sheet laminate in which electromagnetic steel sheets 1 are laminated to a desired height s along the rotor axial direction L, and a rotary shaft shaft slot 3 is opened at the center thereof. In the end region, two magnet slots 2 and 2 opened in a substantially V shape are formed as a set along the circumferential direction. . The rotor core 10 may be 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.

  As shown in FIG. 2, the slot 2 for magnets (Embodiment 1) is a region 2a having a rectangular planar shape into which two divided magnets are inserted (the length of the long side is t1, the length of the short side is t3). ) And two convex regions 2b and 2c for suppressing leakage magnetic flux.

  As shown in FIG. 3, the magnet slot 2 has a rectangular area 2a in which the two planar shapes are rectangular magnets 4 and 4 (the length of the long side of the plane rectangle is t2 and the length of the short side is 2). The height t4 and the height s) of the rotor core 10 are inserted and fixed.

Here, the divided magnets 4 (permanent magnets) used include rare earth magnets, ferrite magnets, alnico magnets, etc., and the rare earth magnets are ternary neodymium magnets in which iron and boron are added to neodymium. And a samarium cobalt magnet and a samarium iron nitrogen magnet made of a binary alloy of samarium and cobalt. Among these, rare earth magnets have a higher maximum energy product (BH) _max compared to ferrite magnets and alnico magnets, and therefore are suitable for application to rotors for drive motors such as hybrid vehicles that require high output.

  The lengths of the two divided magnets 4 and 4 are such that t1> 2t2 and t3> t4 so that the planar shape can move within the rectangular region 2a in the magnet slot 2. Is set.

  As described above, the rotor core 10 and the divided magnets 4 of the radix obtained by multiplying the number of magnetic poles by four per one magnetic pole are prepared (first step).

  Next, as shown in FIG. 4 a, the two divided magnets 4, 4 are inserted into the rectangular area 2 a constituting each magnet slot 2. In the insertion of the divided magnets 4 and 4, as shown in FIG. 4b, the divided magnets 4 and 4 are inserted so as to form a gap G between them. That is, the split magnets 4 and 4 may be inserted in a state where the gap G is secured, or the gap G may be formed after the split magnets 4 and 4 are inserted in a contact posture.

  As described above, the gap G can be formed when both the magnet slot 2 and the segmented magnet 4 are manufactured so as to satisfy the relational expression of t1> 2t2.

  When the two divided magnets 4 and 4 are inserted in the magnet slot 2 in a posture having a gap G between them, as shown in FIG. 5a, the mold resin material 5 is injected using the gap G as an injection start point. .

  The mold resin material 5 injected with the gap G as an injection start point pushes the two divided magnets 4 and 4 to the left and right ends by filling the gap G, and the injected mold resin material 5 is further removed from the gap G. It flows out and flows into the other region of the slot 2 for magnets (X1 direction in FIG. 5a). The flow of the mold resin material 5 is made possible by making both the magnet slot 2 and the divided magnet 4 so as to satisfy the relational expression of t3> t4 as described above.

  The mold resin material 5 completely fills the gap G and the other area of the magnet slot 2 and hardens, so that the two divided magnets 4 and 4 are fixed in a position apart from each other in the magnet slot 2. Structure is formed.

  And the rotor 100 shown in FIG. 5 b is manufactured by forming this magnet slot internal structure in all the magnet slots 2.

  According to the rotor 100 shown in the figure, in the magnet slot 2, the two divided magnets 4, 4 are fixed in a posture separated from each other, so that the divided magnets 4, 4 are in contact with each other in the magnet slot. When fixed, problems such as an increase in eddy current loss due to the conductive state between both magnets are effectively solved.

(Embodiment 2 of slot for magnet)
FIG. 6 a is a plan view showing the magnet slot according to the second embodiment together with two divided magnets 4 and 4.

  The magnet slot 2A shown in the figure is provided with a convex portion 2d having a triangular planar shape in the middle of the long side of the region 2a having a rectangular planar shape constituting the slot. Then, when there are two divided magnets 4 and 4 in a region 2a having a rectangular planar shape, the convex portion 2d is set to a dimension that wraps around the long side of each of the two divided magnets 4 and 4. Yes.

  6b, when the mold resin material 5 is injected into the gap G between the divided magnets 4 and 4, the mold resin material 5 flows into the two convex portions 2d and 2d after filling the gap G (in the X2 direction). ), And flows between the long sides of the two divided magnets 4 and 4 and the slot wall surface of the rectangular region 2a through the convex portion 2d, and further flows into the convex regions 2b and 2c on the side. For this reason, the two divided magnets 4 and 4 maintain a posture separated from each other by the mold resin material 5, and the two divided magnets 4 and 4 both have a rectangular area 2 a of the magnet slot 2 </ b> A. Magnet inner slot fixing (fixing at the center position of the magnet slot) can be achieved in a posture separated via the molding resin material 5 without being in close contact with the long side to be configured.

  As a result, the two divided magnets 4 and 4 do not come into contact with each other, and the divided magnets 4 and 4 do not come into contact with the wall surfaces corresponding to the long sides of the divided magnet 4 and the magnet slot 2A. Eddy current loss due to the divided magnets 4 and 4 being brought into close contact with each other and brought into a conductive state, and further, the wall surfaces of the divided magnets 4 and the magnet slot 2A being brought into close contact and brought into a conductive state. Can be effectively deterred. That is, an even higher eddy current loss suppression effect can be expected as compared with the magnet slot 2 (Embodiment 1).

(Embodiments 3 and 4 of slot for magnet)
FIG. 7A is a plan view showing a third embodiment of the magnet slot, and FIG. 7B is a plan view showing a fourth embodiment of the magnet slot.

  The magnet slot 2B according to the third embodiment has a convex portion 2e having a semicircular planar shape, and the magnet slot 2C according to the fourth embodiment has a convex portion 2f having a semi-elliptical planar shape. It is what you have.

  The convex portions 2d, 2e, and 2f, including the triangular convex portion 2d, smoothly guide the mold resin material that has flowed from the gaps between the divided magnets to other regions by the wall surfaces of the convex portions that form these shapes. Therefore, it is possible to effectively flow the mold resin material between the long side of the rectangular region of the magnet slot and the long side of the divided magnet.

  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 ... Magnetic steel sheet, 2, 2A, 2B, 2C ... Magnet slot, 2a ... Rectangular area (planar shape), 2b, 2c ... Convex area, 2d, 2e, 2f ... Convex part, 3 ... Rotating shaft Slot for shaft, 4 ... split magnet, 5 ... mold resin material, 10 ... rotor core, 100 ... rotor, G ... gap

Claims (3)

A method for manufacturing a rotor for an IPM motor in which two magnets having a rectangular shape in a planar shape having a length in the rotor axial direction are embedded in a magnet slot provided in a direction along the rotor axis,
The planar shape of the magnet slot is a combination of a rectangle having a long side and a short side, and a convex shape protruding outward from each of the two short sides, and the long side of the magnet slot is long. When the length is t1 and the length of the long side of the divided magnet corresponding to the long side is t2, the relationship of t1> 2t2 is established, and the two divided magnets are magnets. A first step of preparing a rotor core having a magnet slot and a split magnet, the planar shape being movable within a rectangular region among the slots for use;
Two split magnets are arranged in a magnet slot in a posture with a gap between them, and a mold resin material for fixing the divided magnet is injected into the gap so that at least the divided magnets do not come into contact with each other. A method for manufacturing a rotor for an IPM motor comprising a second step of fixing two divided magnets in a slot for molding with a mold resin. Of the magnet slot, a convex portion is provided in the middle of the long side, and when there are two divided magnets in a region where the planar shape is a rectangle, the convex portion is the length of each of the two divided magnets. The dimension of the convex part is set to wrap around the side,
The mold resin material injected into the gap in the second step fills the gap, and then enters the gap between the long side of the split magnet and the long side of the magnet slot through the convex portion. The manufacturing method of the rotor for IPM motors of Claim 1 to fill.   The method for manufacturing a rotor for an IPM motor according to claim 2, wherein a planar shape of the convex portion is any one of a triangle, a semi-elliptical shape, and a semi-circular shape.

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