JP2009044819A - Rotor for magnet-embedded motor and its manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a rotor for a magnet-embedded motor which can effectively prevent an eddy current loss, and can significantly reduce rotor manufacturing cost. <P>SOLUTION: The manufacturing method of the rotor for the magnet-embedded motor having a plurality of permanent magnets 2 embedded in a rotor core 1 includes a first process for inserting the permanent magnets 2 into magnet insertion slots 12 of the rotor core 1, and a second process for dividing the permanent magnets 2 into a plurality of permanent magnet divided bodies 2a, by pressing the permanent magnets by using upper and lower end plates 3, 3 in such an attitude that the permanent magnets 2 inserted into the slots 12. Grooves 21 are formed at both ends of the permanent magnets 2; protrusions 31 are formed in positions corresponding to the grooves 21 on the end plates 3; and the permanent magnet divided bodies are formed with high accuracy due to the effect that the protrusions 31 are pressed into the grooves 21, in an attitude where the protrusions are being fitted into the grooves. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a magnet embedded motor rotor and a method of manufacturing the same.

  Among various types of motors including a brushless DC motor, a 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, a motor having a magnet-embedded rotor as described above is used as a motor for a hybrid vehicle.

  By the way, a coil is formed in the stator teeth by concentrated winding or distributed winding. A magnetic flux is generated by applying a current to the coil, and magnet torque and reluctance are generated between the stator teeth and the magnetic flux. Torque is generated. In the case of this distributed winding coil, the number of magnetic poles is larger than in the case of the concentrated winding coil. Therefore, the magnetic flux (or change in magnetic flux) that enters the permanent magnet of the rotor from the teeth side when the rotor rotates is relative. Has continuity. 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 concentrated winding coils, the change in magnetic flux density is relatively large, so eddy currents are likely to be generated in the permanent magnets. The generation of eddy currents causes the permanent magnets to generate heat, and irreversible thermal demagnetization occurs. Inviting the magnetic properties of the permanent magnet itself will be reduced.

  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. As a result, the fluctuation rate of the magnetic field acting on the magnet increases due to an increase, and as a result, the eddy current is likely to be generated. The problem that it leads to is generated.

  In order to prevent the generation of the eddy current and the induction of thermal demagnetization due to it, in a motor provided with a permanent magnet embedded rotor, the permanent magnet is formed from a plurality of divided pieces. Measures have been taken to bundle the divided pieces and insert them into the insertion groove of the rotor (for example, see Patent Documents 1 and 2).

JP 2006-136130 A JP 2000-324736 A

  In order to effectively prevent the generation of eddy currents that can occur in the permanent magnet, it is an effective method to manufacture the permanent magnet from a plurality of divided pieces. However, in comparison with manufacturing a solid permanent magnet, the manufacturing method of dividing this into a plurality of divided pieces and bundling them is currently very low in manufacturing efficiency, which greatly increases the manufacturing cost. In addition, when the divided pieces are bonded to each other or the mold body is manufactured, a new problem has arisen that the manufacturing cost is further increased due to an increase in manufacturing steps and manufacturing labor.

  The present invention has been made in view of the above-described problems, and in a permanent magnet embedded in a rotor for a magnet-embedded motor, eddy current loss is effectively prevented and the rotor manufacturing cost is greatly reduced. An object of the present invention is to provide a method for manufacturing a rotor for a magnet-embedded motor that can be used, and a rotor for a magnet-embedded motor manufactured by the manufacturing method.

  In order to achieve the above object, a method for manufacturing a rotor for a magnet-embedded motor according to the present invention is a method for manufacturing a rotor for a magnet-embedded motor in which a plurality of permanent magnets are embedded in a rotor core. A first step of inserting the permanent magnet into the slot for insertion, and a second step of dividing the permanent magnet into a plurality of pieces in the posture in which the permanent magnet is inserted into the slot. To do.

  The method for manufacturing a rotor for a magnet-embedded motor according to the present invention can be performed by dividing a single permanent magnet after inserting it into a rotor slot, or by dividing a plurality of magnets after inserting a plurality of magnet divided bodies into the slot. The present invention relates to a method for manufacturing a rotor that can improve the manufacturing efficiency of a permanent magnet, and thus the manufacturing efficiency of a rotor, by forming a body.

  Here, the permanent magnet is a ternary neodymium magnet obtained by adding iron and boron to neodymium, a samarium cobalt magnet made of a binary alloy of samarium and cobalt, a ferrite magnet mainly composed of iron oxide powder, An appropriate magnet can be applied in consideration of cost and magnetic characteristics, such as an alnico magnet made of aluminum, nickel, cobalt, or the like. Among them, it is preferable to apply a neodymium magnet having a high maximum energy product and relatively inexpensive.

  As one embodiment of the manufacturing method of the present invention, protrusions are formed on the two non-magnetic end plates attached to both end faces of the rotor, and the protrusions are formed on the end faces of the permanent magnets inserted into the slots. There is a form in which the permanent magnet is divided by abutting and pressing the end plate.

  Here, examples of the non-magnetic material for the end plate include aluminum and its alloys, copper and its alloys, and the like.

  Here, it is preferable that grooves are formed at both end surfaces of the permanent magnet at positions corresponding to the protrusions of the end plate, and the end plate is pressed in a posture in which the protrusions are positioned in the grooves. In this case, it is desirable that the grooves formed on both end faces of the permanent magnet facing both end faces of the rotor are formed at corresponding positions, for example, three grooves are formed at corresponding positions on the upper and lower end faces. As a result, the magnets can be easily divided along the dividing line (the slot insertion direction or substantially the insertion direction of the permanent magnet) that connects the grooves at the corresponding positions.

  As another embodiment of the manufacturing method of the present invention, grooves are formed on both end faces of the permanent magnet, and an expansion piece made of a material having a larger linear expansion coefficient than the permanent magnet is formed in the groove. In the second step, there is also a mode in which the expansion piece is expanded by heating the permanent magnet and the permanent magnet is divided.

  Here, the expansion piece to be used has only to have a shape and a size that can enter at least a part of the groove, and does not necessarily have a shape and a size that match the groove shape. In addition, the linear expansion coefficient is at least larger than that of the permanent magnet, and when heated, the material has a linear expansion coefficient and hardness that can divide the permanent magnet by relatively increasing the amount of thermal deformation of the expansion piece. That's fine. Examples of such materials include fluororesin and polyamide.

  In another embodiment of the manufacturing method of the present invention, first grooves are formed at positions corresponding to the protrusions of the end plate on both end faces of the permanent magnet, and the slot insertion direction of the permanent magnet A plurality of second grooves are formed on both end faces of the magnet, and expansion pieces made of a material having a larger linear expansion coefficient than the permanent magnet are disposed in the second grooves. In the second step, the permanent magnet is divided in the slot insertion direction by pressing the end plate in a posture in which the protrusion is positioned in the first groove, and the permanent magnet is heated by heating the permanent magnet. There is also a form in which the expansion piece is expanded and the permanent magnet is divided in a direction perpendicular to the slot insertion direction.

  In the present embodiment, the permanent magnet inserted into the rotor slot is divided into two directions, that is, a slot insertion direction (or substantially insertion direction) and a direction orthogonal to this (or substantially orthogonal direction). Generation of eddy currents can be further suppressed by increasing the number of divided bodies (number of divisions) in the rotor.

  Here, in addition to the method of heating the rotor core and the permanent magnet with an arbitrary heating device, the permanent magnet is heated by driving the motor to actively generate eddy currents in the permanent magnets. May generate heat. In this embodiment, a vortex loss occurs only at the initial stage of motor driving, but a rotor and a motor with no vortex loss or reduced vortex loss as much as possible after the permanent magnet is divided can be obtained.

  In addition to the flat plate shape or the flat rod shape, a curved permanent magnet can be used as the previously divided permanent magnet, and in this case, a groove is formed at least on the concave surface side. A permanent magnet is inserted into the slot while being stacked in the slot insertion direction.

  When the concave side of the curved shape becomes the tension side when pressed, and becomes the starting point of division, at least one groove or grooves are formed on the concave side. Of course, grooves may be formed at corresponding positions on the convex and concave surfaces of the curved shape.

  Furthermore, as another embodiment of the manufacturing method of the present invention, in the first step, the permanent magnets are stacked in the slot insertion direction, and grooves are formed at corresponding positions on the opposing surfaces of adjacent permanent magnets. There is also a form in which the spacer is inserted into the slot with a spacer interposed between the grooves, and the permanent magnet is pressed by an end plate or the like in this state.

  Here, the spacer used is formed of a material having a high hardness such as ceramics, and the permanent magnet is moved up and down in a posture in which the spacer is disposed in a groove formed in the upper and lower permanent magnet divided bodies. The permanent magnet is divided in the slot insertion direction. Furthermore, the spacer having high hardness is interposed in the divided gap portion in the slot insertion direction, and a permanent magnet divided body in which the predetermined gap is held by the spacer can be formed in the slot.

  According to the rotor manufacturing method of the present invention described above, one permanent magnet can be divided in the rotor slot, or a plurality of permanent magnet divided bodies can be divided into more divided bodies in the rotor slot. The manufacturing efficiency of the motor can be significantly improved.

  The rotor manufactured by the method for manufacturing a rotor according to the present invention is suitable for a drive motor of a hybrid vehicle or an electric vehicle, which has recently been mass-produced and is expected to have high output performance.

  As can be understood from the above description, according to the method for manufacturing a rotor for a magnet-embedded motor of the present invention, a permanent magnet divided body can be efficiently obtained, and the manufacturing efficiency of the rotor and the motor can be improved. In addition, it is possible to manufacture a high-performance rotor and motor in which the occurrence of thermal demagnetization is reduced.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view for explaining a rotor manufacturing method of the present invention, and FIG. 2 is a longitudinal sectional view showing an embodiment of a permanent magnet divided body in a rotor slot. FIG. 3 is a diagram for explaining the groove depth range of the permanent magnet, FIG. 3a is a front view thereof, and FIG. 3b is a graph showing the relationship between the groove depth and the pressing force. FIG. 4 is a diagram for explaining another embodiment of the permanent magnet divided body. FIG. 4a shows the permanent magnet in a state before the division, and FIGS. 4b and 4c both show the permanent magnet divided body. FIG. FIGS. 5 to 8 are diagrams for explaining still another embodiment of the permanent magnet divided body, in which FIG. 5a shows the permanent magnet before being divided, and FIG. 5b shows the permanent magnet divided body. FIG.

  FIG. 1 is an exploded perspective view of a rotor for an embedded magnet motor. In this rotor, a permanent magnet 2 is inserted and fixed in a slot 12 formed in a rotor core 1 in which a silicon steel plate 11 is laminated and fixed at a predetermined height, and nonmagnetic material made of aluminum, copper or the like is formed at both ends of the rotor core 1. End plates 3 and 3 are mounted.

  The permanent magnet 2 is divided into a plurality of permanent magnet divided bodies after being inserted into the slot 12. Specifically, a predetermined number of grooves 21 are formed at both end portions facing the rotor end portions of all the permanent magnets 2, and these permanent magnets 2 are respectively inserted into the corresponding slots 12. Next, the end plates 3 and 3 having the protrusions 31 are mounted at positions corresponding to the grooves 21 at the end of the permanent magnet 2 when mounted on the end of the rotor core 1. Next, by pressing these from above and below, the permanent magnet 2 is divided into a plurality of permanent magnet divided bodies extending in the slot insertion direction by a pressing force (compression force) acting from the projection 31 fitted in the groove 21. It is.

  FIG. 2 is a longitudinal sectional view showing the permanent magnet divided body 2a formed in the slot 12 by the above method. In the illustrated example, three grooves 21, 21, 21 are formed at equal intervals, and four permanent magnet divided bodies 2a having the same width are formed. When the permanent magnet divided body 2a is formed, the groove 31 of the end plate 3 enters between the permanent magnet divided bodies 2a and 2a on both sides to form the air gap G and hold it. The protrusion 31 has a protruding wedge shape on the groove side, but is not limited to the illustrated form.

[Experiment and results for determining the depth range of the permanent magnet end]
The present inventors tried an experiment for setting the depth range of the groove formed at the end of the permanent magnet. In this experiment, as shown in FIG. 3A, the height of the permanent magnet piece is H (= 6.5 mm), the height of the grooves formed on the upper and lower ends is h (= 1 to 2 mm), and the groove height with respect to the total height H is shown. Test pieces were prepared by changing the ratio of the length h in various ways, and the quality of formation of the permanent magnet divided body was verified by pressing each end piece with an end plate from both ends. The result is shown in FIG.

As a result of the experiment, when h is less than 1 / 10H (A1 region in FIG. 3b), the permanent magnet cannot penetrate through the top and bottom, for example, the whole permanent magnet breaks, and the formability is not good. It was.
Further, when h exceeds 1 / 3H (A3 region in FIG. 3b), there is a problem that it becomes easy to break at the stage before pressing with the end plate, for example, at the slot insertion stage, and the insertion work is hindered.

  On the other hand, in the range where h is 1 / 10H and 1 / 3H (A2 region in FIG. 3b), none of the above problems occurred, and a permanent magnet divided body having a desired quality could be obtained.

  FIG. 4 shows another embodiment of the permanent magnet divided body. In this embodiment, as shown in FIG. 4a, rectangular grooves 2A1 are formed in the upper and lower ends of the permanent magnet 2A, and the expansion piece 4 is disposed in the groove. Here, the expansion piece 4 has a linear expansion coefficient that is at least larger than that of the permanent magnet 2A. When the expansion piece 4 is heated or the like, the amount of thermal deformation of the expansion piece 4 becomes relatively large so that the permanent magnet 2A can be divided. A material having a linear expansion coefficient and hardness, for example, a fluororesin may be press-fitted at about 300 ° C.

  After this is inserted into the rotor slot, the expansion piece 4 is expanded by heating the permanent magnet 2A, whereby the permanent magnet 2A is made into a plurality of permanent magnet divided bodies 2A ′, and an air gap G can be formed (FIG. 4b). reference). Here, in addition to the method of heating the rotor core 1 and the permanent magnet 2A by an arbitrary heating device, the permanent magnet is heated by driving the motor to actively generate an eddy current in the permanent magnet 2A. There is also a method of causing the permanent magnet 2A to generate heat.

  Although FIG. 4 b divides the permanent magnet in the slot insertion direction, as shown in FIG. 4 c, the permanent magnet may be divided in a direction orthogonal to the slot insertion direction.

  FIG. 5 shows still another embodiment of the permanent magnet divided body. In this embodiment, as shown in FIG. 5a, grooves 2B1 are formed at corresponding positions on the upper and lower ends of the permanent magnet 2B, and separate grooves 2B2 are formed at corresponding positions on both the left and right ends of the permanent magnet 2B. In addition, the expansion piece 4 similar to the above is disposed in the groove 2B2.

  After this is inserted into the rotor slot, it is pressed by the end plates 3 and 3 and the permanent magnet 2B is heated (including heat generated by the eddy current), so that the central permanent magnet divided body 2B ′ and the left and right smaller areas can be obtained. A permanent magnet divided body composed of the divided permanent magnet divided body 2B ″ can be formed (see FIG. 5b).

  FIG. 6 shows still another embodiment of the permanent magnet divided body. In this embodiment, as shown in FIG. 6a, a permanent magnet divided body 2C1 having a curved shape and having a groove 2C11 formed at the center of the concave surface is inserted into the slot, and the divided bodies are stacked in the slot insertion direction. A permanent magnet divided body 2C2 that is further divided into small pieces is formed by pressing the upper and lower end plates 3 and 3 as shown in FIG. 6B.

  Compared with the embodiment shown in FIG. 6, FIG. 7 inserts a permanent magnet segment 2D1 having more grooves 2D11 in the center of the concave surface into the slot and laminates it to form a permanent magnet 2D. This is similarly pressed from above and below to form a permanent magnet divided body 2D2 that is further subdivided.

  FIG. 8 shows still another embodiment of the permanent magnet divided body. In this embodiment, as shown in FIG. 8a, two permanent magnet divided bodies 2E1 and 2E1 each having a flat plate shape, each having a groove 2E ′ formed at a corresponding position on the opposing surface of each divided body. Magnet division bodies 2E1 and 2E1 are prepared, laminated in a posture in which hard spacers 5 made of ceramics or the like are disposed in the grooves 2E ′ and 2E ′, and inserted into the rotor slot to end plate from above and below. 3 and 3 are pressed.

  When the end plates 3 and 3 are pressed, a dividing line is formed in the vertical direction from the groove 2E ′ as shown in FIG. 8B. Thus, when the spacer 5 enters the gap between the small divided bodies 2E2 and 2E2, a permanent magnet divided body as shown in FIG. 8b is formed.

  According to the above-described method for manufacturing a rotor for a magnet-embedded motor according to the present invention, it is possible to efficiently form a permanent magnet divided body in a rotor slot, and to secure an air gap between the divided bodies. Therefore, it is possible to increase the manufacturing efficiency and suppress the generation of eddy currents, thereby manufacturing a rotor and a motor excellent in output performance.

  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.

It is a disassembled perspective view explaining the manufacturing method of the rotor of this invention. It is the longitudinal cross-sectional view which showed one Embodiment of the permanent magnet division body in a rotor slot. It is the figure explaining the groove depth range of a permanent magnet, Comprising: (a) is the front view, (b) is the graph which showed the relationship between groove depth and pressing force. It is the figure explaining other embodiment of a permanent magnet division body, (a) has shown the permanent magnet of the state before a division | segmentation, (b), (c) showed the permanent magnet division body both FIG. It is the figure explaining other embodiment of a permanent magnet division body, Comprising: (a) has shown the permanent magnet of the state before a division | segmentation, (b) is the figure which showed the permanent magnet division body.

It is the figure explaining other embodiment of a permanent magnet division body, Comprising: (a) has shown the permanent magnet of the state before a division | segmentation, (b) is the figure which showed the permanent magnet division body. It is the figure explaining other embodiment of a permanent magnet division body, Comprising: (a) has shown the permanent magnet of the state before a division | segmentation, (b) is the figure which showed the permanent magnet division body. It is the figure explaining other embodiment of a permanent magnet division body, Comprising: (a) has shown the permanent magnet of the state before a division | segmentation, (b) is the figure which showed the permanent magnet division body.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Rotor core, 11 ... Silicon steel plate, 12 ... Slot, 2, 2A, 2B, 2C, 2D ... Permanent magnet, 2A ', 2B', 2B ", 2C1, 2C2, 2D1, 2D2, 2E1, 2E2 ... Permanent magnet division Body, 21, 2A1, 2B1, 2B2, 2C11, 2D11 ... groove, 3 ... end plate, 4 ... expansion piece, 5 ... spacer, G, G1, G2 ... air gap

Claims (9)

A method for manufacturing a rotor for a magnet-embedded motor in which a plurality of permanent magnets are embedded in a rotor core,
A first step of inserting the permanent magnet into the magnet insertion slot of the rotor;
And a second step of dividing the permanent magnet into a plurality of parts in a posture in which the permanent magnet is inserted into the slot. In the second step,
Protrusions are formed on the two non-magnetic end plates attached to both end faces of the rotor, and the protrusions are brought into contact with the end faces of the permanent magnets inserted into the slots, and the end plates are pressed. The method for manufacturing a rotor for an embedded magnet motor according to claim 1, wherein the permanent magnet is divided. In the manufacturing method of the rotor for magnet embedded motors of Claim 2,
Grooves are formed at positions corresponding to the protrusions of the end plate on both end faces of the permanent magnet, and the rotor for an embedded magnet motor presses the end plate in a posture in which the protrusions are positioned in the grooves. Manufacturing method. In the manufacturing method of the rotor for magnet embedded motors according to claim 1,
Grooves are formed on both end faces of the permanent magnet, and expansion pieces made of a material having a larger linear expansion coefficient than the permanent magnet are disposed in the groove,
In the second step, a method for manufacturing a rotor for a magnet-embedded motor, wherein the expansion piece is expanded by heating the permanent magnet to divide the permanent magnet. In the manufacturing method of the rotor for magnet embedded motors of Claim 2,
First grooves are formed on both end faces of the permanent magnet at positions corresponding to the protrusions of the end plate, and a plurality of second grooves are spaced at both end faces in the slot insertion direction of the permanent magnet. And an expansion piece made of a material having a larger linear expansion coefficient than the permanent magnet is disposed in the second groove,
In the second step, the permanent magnet is divided in the slot insertion direction by pressing the end plate in a posture in which the protrusion is positioned in the first groove, and the expansion piece is formed by heating the permanent magnet. A method for manufacturing a rotor for a magnet-embedded motor, which expands and divides a permanent magnet in a direction perpendicular to the slot insertion direction. In the manufacturing method of the rotor for magnet embedded motors according to claim 4 or 5,
The method of manufacturing a rotor for a magnet-embedded motor, wherein the heating of the permanent magnet is to drive a motor to generate an eddy current in the permanent magnet and to generate heat by the eddy current. In the manufacturing method of the rotor for magnet embedded motors according to claim 1,
In the first step, a permanent magnet having a curved permanent magnet and having a groove formed on the concave side thereof is inserted into the slot while being laminated in the slot insertion direction. Production method. In the manufacturing method of the rotor for magnet embedded motors according to claim 1,
In the first step, permanent magnets are stacked in the slot insertion direction, and grooves are formed at corresponding positions on the opposing surfaces of adjacent permanent magnets, and inserted into the slots with a spacer interposed between the grooves. A method of manufacturing a rotor for a magnet-embedded motor. A rotor for a magnet-embedded motor manufactured by the manufacturing method according to claim 1.

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