JP6164093B2 - Method for manufacturing permanent magnet - Google Patents

Description

  The present invention relates to a method for manufacturing a permanent magnet embedded in a rotor of a permanent magnet type rotating electrical machine.

  Conventionally, a permanent magnet type rotating electrical machine has been used as a drive source for railway vehicles and electric vehicles. As is well known, a plurality of permanent magnets are embedded in a rotor of a permanent magnet type rotating electrical machine. When the rotary electric machine is driven, a strong magnetic flux generated by the stator coil penetrates the permanent magnet, so that a large eddy current is generated in the permanent magnet. As a result, there is a problem that not only the loss of the rotating electrical machine is increased and the efficiency is lowered, but also the demagnetization of the permanent magnet occurs due to heat generation.

  As a countermeasure, a plurality of insulated permanent magnet pieces are combined to form a permanent magnet. The eddy current generated in the permanent magnet is reduced while reducing the eddy current generated in the permanent magnet. Has been done to reduce.

  For example, in Patent Document 1, a plurality of permanent magnet pieces are each covered with an insulating film, and the plurality of permanent magnet pieces are joined to manufacture a permanent magnet that can be handled as a member made of a plurality of permanent magnet pieces. Techniques to do this are disclosed. In Patent Document 1, in order to ensure the dimensions of the finally obtained permanent magnet, the permanent magnet pieces are joined to obtain one permanent magnet, and then the permanent magnet is ground to a specified dimension by grinding or the like. After that, covering the entire surface of the permanent magnet with an insulating film is also disclosed.

JP 2003-134750 A

  According to such a technique of Patent Document 1, problems such as generation of eddy currents, and consequently reduction in efficiency of the rotating electrical machine and demagnetization of the permanent magnets can be reduced. However, the technique of Patent Document 1 has a problem in that the processing cost increases because it is necessary to perform coating processing on each of the plurality of permanent magnet pieces and joining processing of the plurality of magnet pieces. In addition, since a single permanent magnet is formed by joining a plurality of permanent magnet pieces, it is difficult to maintain the dimensions and the yield is deteriorated. Then, an object of this invention is to provide the manufacturing method which can manufacture a permanent magnet more simply.

The method for producing a permanent magnet according to the present invention is a method for producing a permanent magnet embedded in a rotor of a permanent magnet type rotating electrical machine, wherein a slit for dividing is formed in a magnet base material, and the slit is formed. A step of coating the entire outer surface of the magnet base material with an insulating coating having elasticity, and an external impact is applied to the magnet base material coated with the insulating coating, and only the magnet base material in the insulating coating is applied. And a step of dividing.

  According to the present invention, it is only necessary to coat the magnet base material, and a step of joining the divided magnet pieces is not necessary, so that a permanent magnet can be manufactured more easily.

It is a figure which shows the manufacturing process of the permanent magnet which is embodiment of this invention. It is a figure which shows an example of the rotary electric machine to which a permanent magnet is applied.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a manufacturing process of a permanent magnet 10 according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of a permanent magnet type rotating electrical machine 100 to which the permanent magnet 10 is applied.

  First, the permanent magnet type rotating electrical machine 100 will be briefly described with reference to FIG. The rotating electrical machine 100 includes an annular stator 110 and a columnar rotor 120 disposed coaxially with the stator 110. The stator 110 includes a stator core 111 and a plurality of coils 112, and the plurality of coils 112 are accommodated in slots formed at equal angular intervals on the same circumference around the rotation shaft 123. .

  The rotor 120 includes a rotor core 121, a rotating shaft 123 that rotates integrally with the rotor core 121, and a plurality of permanent magnets 10. The plurality of permanent magnets 10 are equally formed around the axis O in the circumferential direction. In the slot. In addition, although the form which arrange | positions the permanent magnet 10 of a top view rectangle in a substantially V shape is illustrated in FIG. 1, the shape of the permanent magnet 10 is not restricted to a rectangle, An arc shape may be sufficient. Further, the permanent magnets 10 may be arranged at intervals in the same circumference instead of being V-shaped.

  When such a rotating electrical machine 100 is driven, a strong magnetic flux generated by the stator coil 112 penetrates the permanent magnet 10, so that a large eddy current is generated in the permanent magnet 10. As a result, there is a problem that not only the loss of the rotating electrical machine 100 is increased and the efficiency is lowered, but also the permanent magnet 10 is demagnetized due to heat generation.

  As a countermeasure, a permanent magnet 10 is configured by combining a plurality of magnet pieces that have been conventionally insulated, thereby reducing the generated eddy current and retaining the eddy current in each magnet piece. It has been proposed to reduce the eddy currents that occur. According to such a technique, eddy currents generated in the magnet pieces can be reduced by staying in the individual magnet pieces. The dividing direction of the permanent magnet 10 may be the axial direction as in the laminated steel plate, or may be the circumferential direction.

  However, many of the conventional techniques have a problem that it is necessary to coat each magnet piece with an insulating coating, which is costly. Moreover, in order to improve the insertability of the permanent magnet 10 into the slot, a technique for joining a plurality of magnet pieces to each other has also been proposed, but in this case, a joining process is separately required. In this case, there is a problem that not only the cost is high, but it is difficult to maintain the dimensions of the permanent magnet 10 because a single permanent magnet 10 is constituted by a plurality of magnet pieces.

  Therefore, in the present embodiment, the permanent magnet 10 is manufactured by a method that can reduce manufacturing costs and ensure dimensional accuracy. A method for manufacturing the permanent magnet 10 will be described with reference to FIG.

  When manufacturing the permanent magnet 10, the magnet base material 12 is prepared first (FIG. 1 (a)). The magnet base material 12 is made of a rare earth magnet or a ferrite magnet. The size of the magnet base material 12 is adjusted to be approximately the same as the size of the permanent magnet 10 to be finally obtained.

  Next, in order to cleave the magnet base material 12 into a plurality of magnet pieces 18, slits 14 are formed in advance in the part of the magnet base material 12 to be cleaved as shown in FIG. The shape of the slit 14 is not particularly limited, but is required to have such a depth and sharpness that the magnet base material 12 is cleaved when subjected to an external impact described later. The position of the slit 14 is not particularly limited, but in this embodiment, the slit is formed only on one side of the magnet base material 12. As a method of forming the slit, a method of providing in a molding process of the magnet base material 12 by a slit forming rib provided in a molding die of the magnet base material 12, a method by machining such as a dicer or a slicer, a method by laser beam irradiation, There is a method by wire cut electric discharge machining.

  If the slit 14 is formed, the entire surface of the magnet base material 12 is then covered with an insulating coating 16. The insulating coating 16 used here is made of a material having a certain degree of elasticity, such as a fluorine-based resin, so that it does not break even when subjected to an impact. The method for coating the insulating coating 16 is not particularly limited as long as it can be coated with a uniform thickness. Therefore, for example, the insulating coating 16 may be formed by spraying a fluorine-based resin on the entire surface of the magnet base material 12 and then baking it at a predetermined temperature.

  If the insulating coating 16 is formed, finally, an impact is applied to the coated magnet base material 12 from the outside, and the magnet base material 12 in the insulating coating 16 is cleaved into a plurality of magnet pieces 18. For example, it is conceivable that the impact is applied in the form of so-called three-point bending, in which the impact is applied to the opposite side surface of the slit 14 while both sides of the slit 14 are supported. Under such an impact, the magnet base material 12 is divided into a plurality of magnet pieces 18. However, since the insulating coating 16 has elasticity, it does not break even when subjected to an impact, and the plurality of magnet pieces 18 as a whole. Keep the state covered. In other words, the plurality of magnet pieces 18 can be handled as one component, the permanent magnet 10, covered with the insulating coating 16.

  By the way, the permanent magnet 10 obtained in this way is divided into a plurality of magnet pieces 18, and contact resistance is always generated between the magnet pieces 18. When this contact resistance is generated, eddy currents generated in the magnet pieces 18 remain in the individual magnet pieces 18 and are reduced, as in the case where an insulating material is sandwiched between the magnet pieces 18. As a result, effects such as loss reduction of the rotating electrical machine 100 and heat generation reduction are produced.

  By the way, although the permanent magnet 10 of the present embodiment is divided into a plurality of magnet pieces 18, the entire outer surface remains covered with the insulating coating 16. Can be easily maintained at the specified dimensions. As a result, the yield can be greatly improved.

  Further, in the conventional technique, each of the magnet pieces 18 after being cleaved is coated, and a plurality of times of coating are necessary for manufacturing one permanent magnet 10. On the other hand, in this embodiment, only the magnet base material 12 is cleaved after the entire surface of the magnet base material 12 before cleaving is covered with an insulating film. In other words, since only one coating process is necessary for manufacturing one permanent magnet 10, it is possible to greatly reduce the labor of the coating process compared to the conventional technique. Further, in the conventional technique, a joining step for joining the coated magnet pieces 18 to each other is necessary. However, in the present embodiment, since the plurality of magnet pieces 18 are integrated by the insulating coating 16, the joining is performed. A process becomes unnecessary. That is, according to the present embodiment, it is possible to reduce the labor and the number of processes necessary for manufacturing the permanent magnet 10, and it is possible to reduce the cost required for manufacturing.

  DESCRIPTION OF SYMBOLS 10 Permanent magnet, 12 Magnet base material, 14 Slit, 16 Insulating film, 18 Magnet piece, 100 Rotary electric machine, 110 Stator, 111 Stator core, 112 Coil, 120 rotor, 121 Rotor core, 123 Rotating shaft.

Claims (1)

A method of manufacturing a permanent magnet embedded in a rotor of a permanent magnet type rotating electrical machine,
Forming a slit for splitting in the magnet base material;
Covering the entire outer surface of the magnet base material in which the slit is formed with an insulating coating having elasticity;
Applying an external impact to the magnet base material covered with the insulating coating, and dividing only the magnet base material in the insulating coating;
A method for producing a permanent magnet, comprising: