JP2013240224A - Built-in magnetization method of permanent magnet type motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a built-in magnetization method of a permanent magnet type motor which can reduce damage on an insulating film of a coil surface and facilitate temperature management in built-in magnetization in which a magnetization current is reduced by utilizing a phenomenon in which a saturation magnetization magnetic filed is reduced when a rare earth magnet is at the high temperature.SOLUTION: In a built-in magnetization method of a permanent magnet type motor which includes: a rotor 1 having a shaft 5 which is rotatably supported and a plurality of rare earth magnets 6 on an outer peripheral side; and a stator 2 arranged so as to oppose to the outer side of the rotor 1 with a predetermined gap 20 and having a coil 11, a through hole 12 in a shaft direction is provided in the shaft 5 in advance, the rotor 1 is heated by circulating a heat medium from one end of the through hole 12 to the other end in a motor assembling process and magnetization is made by flowing a current to the coil 11 in the state where the rare earth magnets 6 are at the temperature higher than the room temperature.

Description

  The present invention relates to a built-in magnetization method for a permanent magnet type motor.

  In recent years, the performance of rare earth magnets has advanced rapidly, and magnets with higher magnetic coercive force and higher coercive force have been developed and appeared one after another. Adoption of these magnets is indispensable for improving the performance of motors. However, when a magnet piece pre-magnetized outside the motor is incorporated in or on the surface of the field core, it is difficult to handle due to its high magnetic force. Yes, productivity is reduced. As a means to solve this problem, the magnet is incorporated in the field core in an unmagnetized state, and the magnet is attached by passing a large current (magnetization current) through the armature winding when the rotor and stator are assembled. So-called built-in magnetization that magnetizes is effective.

  However, as the magnetism of rare earth magnets increases and the coercivity increases, the required magnetizing current is also increasing, and there are problems such as increasing the size of the magnetizing power supply and increasing damage to the insulation film of the armature winding. is there. In order to solve this problem, a built-in magnetization method that reduces the magnetization current by utilizing the fact that the saturation magnetization magnetic field of a rare earth magnet decreases at a high temperature is disclosed.

  In Patent Document 1, Claim 2 discloses a method of performing built-in magnetization in a state where the permanent magnet is at a high temperature using a drying process inside the motor (which can be interpreted as the inside of the frame according to the description of the embodiment). In claim 3, a method is disclosed in which built-in magnetization is performed in a state where the permanent magnet is at a high temperature by using a baking coating process on the outer periphery of the motor (which can be interpreted as the outer surface of the frame according to the description of the embodiment). .

  Patent Document 2 discloses a method for performing built-in magnetization in a high-temperature state using the time when the rotor and the shaft are fixed by shrinkage fitting.

JP-A-6-178507 JP-A-6-315252

  However, in the prior art described in Patent Document 1, not only a rotor in which a permanent magnet is incorporated, but also a stator that does not need to be brought to a high temperature state during magnetization is heated. When the stator winding becomes hot, the winding resistance rises, so the voltage required to pass a predetermined magnetizing current increases, and the damage to the insulation film on the winding surface increases due to the high temperature and high voltage. There's a problem. Further, when the temperature of the motor once decreases due to a trouble in the production line immediately after the drying process or the baking coating process, there is a problem that the entire motor needs to be separately heated again. In addition, it is difficult to apply to motors that do not have a drying process or baking coating process.

  Further, the conventional technique described in Patent Document 2 has a problem that temperature management is difficult. The temperature of the rotor is decreasing due to heat dissipation, and the speed depends on the environment such as the temperature and humidity of the atmosphere. Once the optimal temperature is missed, it is difficult to reproduce the same temperature state.

  The present invention has been made in view of the above, and in the built-in magnetization for reducing the magnetizing current by utilizing the fact that the saturation magnetization magnetic field of a rare earth magnet is lowered at a high temperature, the insulating film on the surface of the winding is applied. An object of the present invention is to provide a built-in magnetizing method for a permanent magnet motor that reduces the damage given and makes temperature management easy.

  In order to solve the above-described problems and achieve the object, a built-in magnetizing method for a permanent magnet type motor according to the present invention includes an annular rotor core and a plurality of magnet insertion holes provided on the outer peripheral side of the rotor core. A rotor having a plurality of rare earth magnets mounted on the shaft and a shaft that is rotatably supported by being fitted into a central hole of the rotor core, and an annular ring disposed opposite to the outside of the rotor with a gap. An embedded magnetizing method for a permanent magnet type motor comprising a stator having a stator core and a winding wound around the stator core, and a frame for accommodating the rotor and the stator and supporting the shaft. The shaft is provided with an axial through hole in advance, the stator is fixed inside the frame, the rotor is arranged inside the stator, and the rotor is placed in the frame. A step of heating the rotor by circulating a heat medium through the through hole, and passing a current through the windings when the rare earth magnet has reached a predetermined temperature higher than room temperature. And magnetizing the rare earth magnet.

  According to the present invention, by heating only the rotor, damage to the insulating film on the surface of the winding can be reduced, and temperature adjustment can be performed by controlling the heating and cooling of the heating medium and the flow rate. It has the effect of becoming easy.

1 is a cross-sectional view showing a schematic configuration of a permanent magnet motor according to Embodiment 1. FIG. FIG. 2 is a flowchart showing a built-in magnetization method of the permanent magnet motor according to the first embodiment. FIG. 3 is a cross-sectional view showing a schematic configuration of the permanent magnet motor according to the second embodiment. FIG. 4 is a diagram showing a cross-sectional configuration of the rotor in the third embodiment. FIG. 5 is a diagram showing an image when the contact cross section of the fitting portion in the rotor iron core of the shaft is viewed microscopically in the fourth embodiment.

  Embodiments of a built-in magnetizing method for a permanent magnet motor according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a cross-sectional view showing a schematic configuration of a permanent magnet type motor according to the present embodiment. As shown in FIG. 1, the permanent magnet motor according to the present embodiment (hereinafter simply referred to as “motor”) includes a rotor 1, a stator 2, and a frame 3. FIG. 1 shows the configuration of the motor at the time of magnetization, and the motor is assembled in a state constituted by the rotor 1, the stator 2, and the frame 3.

  The rotor 1 includes a rotor iron core 4, a shaft 5, a rare earth magnet 6, and an end plate 7. The rotor core 4 is formed, for example, by laminating and fixing a plurality of electromagnetic steel plates punched into a predetermined shape. The shape of the rotor core 4 is, for example, a substantially annular shape. The rotor core 4 has magnet insertion holes 30 provided on the outer peripheral side in the circumferential direction, for example, by the number of poles at substantially equal intervals. Each magnet insertion hole 30 extends in the axial direction, and the rare earth magnet 6 is inserted and mounted therein. End plates 7 for preventing the rare earth magnet 6 from coming off in the axial direction are attached to the rotor core 4 at both end surfaces in the axial direction. A shaft 5 is fitted into a shaft fitting hole provided in the center of the rotor core 4, and the shaft 5 is rotatably supported by the frame 3 via a bearing 8. A wave washer 9 for preloading is laid on the bearing surface of the bearing 8. The shaft 5 has a circular cross section, for example, and the shaft fitting hole has a corresponding circular shape.

  The stator 2 includes a stator iron core 10 and a winding 11. The stator core 10 is formed, for example, by laminating and fixing a plurality of electromagnetic steel plates punched into a predetermined shape. The shape of the stator core 10 is, for example, a substantially annular shape. The stator core 10 is provided with a plurality of teeth (not shown), for example, at substantially equal intervals in the circumferential direction on the inner peripheral side, and a winding 11 is wound around these teeth via an insulator (not shown). Be dressed. The stator 2 is fixed to the inner side of the frame 3 by a method such as shrink fitting, for example, and is installed facing the outer side of the rotor 1 with a predetermined gap 20 therebetween. The shaft 5 is provided with an axial through hole 12.

  The frame 3 accommodates the rotor 1 and the stator 2. The frame 3 has, for example, a substantially cylindrical shape, and one end in the axial direction is opened to form a bowl shape, and the other end is provided with a bottom, but the bottom is provided with a hole 22 through which the shaft 5 passes. It has been. That is, in the present embodiment, the shaft 5 is pivotally supported by the frame 3 so as to penetrate the frame 3 in the axial direction.

  Next, a built-in magnetization method for the permanent magnet motor according to the present embodiment will be described with reference to FIGS. FIG. 2 is a flowchart showing a built-in magnetization method for the permanent magnet motor according to the present embodiment.

  The stator 2 is fixed inside the frame 3 by a method such as shrink fitting (S1). Subsequently, the rotor 1 is arranged inside the stator 2 and assembled to the frame 3 (S2). The shaft 5 is provided with an axial through hole 12 in advance. In this state, the motor has the configuration shown in FIG.

  Next, a tube (not shown) connected to a heat source such as a heater and a pump (not shown) is connected to both ends 12a and 12b of the through hole 12 provided in the shaft 5 (S3), and a heat medium is caused to flow through the through hole 12 (S4). ). In FIG. 1, the flow of the heat medium is indicated by solid arrows, and the heat medium flows in one direction from one end 12 a of the through hole 12 to the other end 12 b, for example. When the heat medium flows through the through hole 12, heat is transmitted in the order of the shaft 5, the rotor core 4, and the rare earth magnet 6, and the temperature of the rare earth magnet 6 rises. In FIG. 1, the heat transfer direction is indicated by a dotted arrow. The temperature of the rare earth magnet 6 may be measured directly by providing a small peephole in the end plate 7, or alternatively, the temperature of the surface of the end plate 7 may be measured. The rare earth magnet 6 is made to reach a predetermined temperature by controlling the heating and cooling of the heat medium and the flow rate based on the measured temperature. The temperature of the rare earth magnet 6 is set to be higher than at least room temperature.

  When the rare earth magnet 6 reaches a predetermined temperature, the rotor 1 is fixed at a predetermined angular position, the lead terminal of the winding 11 is connected to a magnetizing power source, and a magnetizing current is applied (S5). If multiple times of magnetization are required depending on the motor specifications, this process is repeated multiple times.

  When the magnetization is completed, the tube is removed from the through hole 12 (S6), and the rest of the motor is assembled (S7).

  In addition, as a substance utilized for a heat medium, water, oil, air, or water vapor | steam can be considered, for example, but oil is suitable in consideration of prevention of rust generation of the shaft 5 and heat conduction efficiency, and handling property is considered. Air is suitable.

  By the above method, only the rotor 1 can be heated without heating the stator 2 in the built-in magnetization for reducing the magnetizing current by utilizing the fact that the saturation magnetization magnetic field of the rare earth magnet 6 is lowered at a high temperature. Therefore, damage to the insulating film on the surface of the winding 11 can be reduced. Moreover, since temperature adjustment can be implemented by controlling the heating and cooling of the heat medium and the flow rate, temperature management is easy.

  Moreover, even if the temperature of the rotor 1 is once lowered due to a trouble in the production line, the heating can be repeated again and again.

  Strictly speaking, since heat is transferred from the outer peripheral surface of the rotor 1 in the order of the air gap 20, the stator core 10, the insulator, and the winding 11, the temperature of the winding 11 also rises. Insulators made of resin or paper have poor heat conductivity, and therefore the rate of temperature rise is very slow, and the temperature rise is not a problem in the magnetization process.

  Moreover, in this Embodiment, although it was set as the structure which provides the single through-hole 12 which flows a heat medium, the structure which provides this in multiple numbers may be sufficient.

Embodiment 2. FIG.
FIG. 3 is a cross-sectional view showing a schematic configuration of the permanent magnet motor according to the present embodiment. FIG. 3 shows the configuration of the motor at the time of magnetization, as in FIG. 1, and the motor is assembled in a state constituted by the rotor 1, the stator 2, and the frame 3.

  As shown in FIG. 3, the shaft 5 is provided with axial through holes 13 and 14 in advance. That is, the shaft 5 is provided with a pair of through holes 13 and 14 that are parallel to each other and penetrate in the axial direction. The mouths of the through holes 13 and 14 at one end of the shaft 5 are connected by, for example, a U-shaped pipe 15. The pipe 15 is connected by a method such as brazing. Thereby, the pipe 15 connects the mouths of the through holes 13 and 14 closely.

  The frame 3 has, for example, a substantially cylindrical shape, and one end in the axial direction is opened to form a bowl shape, and the other end is provided with a bottom. In the present embodiment, unlike the first embodiment, one end of the shaft 5 does not penetrate the frame 3. That is, the end of the shaft 5 on the side where the pipe 15 is mounted is present inside the frame 3 and faces the bottom surface 25 thereof. The other configuration of the present embodiment is the same as that shown in FIG.

  Next, a built-in magnetization method for the permanent magnet motor according to the present embodiment will be described. The flowchart in this case is the same as that in FIG. 2, but the specific contents of S3 and S4 are different from those of the first embodiment. The shaft 5 is provided with axial through holes 13 and 14 in advance, and the stator 2 is shrink fitted (S1) and the rotor 1 is assembled (S2). In this state, the motor has the configuration shown in FIG. Next, a tube (not shown) connected to a heat source such as a heater and a pump is connected to the through holes 13 and 14 with one of the through holes 13 and 14 provided in the shaft 5 as an inlet and the other as an outlet, respectively. The medium is washed away. In the illustrated example, for example, one end 13a of the through hole 13 is used as an inlet, and one end 14a of the through hole 14 is used as an outlet. And after the heat medium which flowed in via the tube connected to the one end 13a of the through-hole 13 flows through the through-hole 13, the pipe 15, and the through-hole 14, the tube connected to the one end 14a of the through-hole 14 is used. Spills through. In FIG. 3, the flow of the heat medium is indicated by solid arrows. When the heat medium flows through the through holes 13 and 14, heat is transmitted in the order of the shaft 5, the rotor core 4, and the rare earth magnet 6, and the temperature of the rare earth magnet 6 rises. In FIG. 3, the heat transfer direction is indicated by a dotted arrow. The temperature of the rare earth magnet 6 may be measured directly by providing a small peephole in the end plate 7, or alternatively, the temperature of the surface of the end plate 7 may be measured. The rare earth magnet 6 is made to reach a predetermined temperature by controlling the heating and cooling of the heat medium and the flow rate based on the measured temperature. The temperature of the rare earth magnet 6 is set to be higher than at least room temperature. The subsequent steps are the same as S5 to S7 in FIG.

  As described above, in the present embodiment, the shaft 5 is provided with the axial through holes 13 and 14, and one end of the through hole 13 and one end of the through hole 14 on the same side are closely connected to each other by the pipe 15. Since the heating medium is passed through the through holes 13 and 14 and only the rotor 1 is heated, damage to the insulating film on the surface of the winding 11 can be reduced. Moreover, since temperature adjustment can be implemented by controlling the heating and cooling of the heat medium and the flow rate, temperature management is easy.

  Further, according to the present embodiment, the heat medium can be circulated even when one end of the shaft 5 cannot be taken out of the frame 3.

  A plurality of pairs of through holes 13 and 14 may be provided. Other configurations, operations, and effects of the present embodiment are the same as those of the first embodiment.

Embodiment 3 FIG.
FIG. 4 is a diagram showing a cross-sectional configuration of the rotor in the present embodiment. The shaft 5 has an axial through hole 12 as in the first embodiment. However, in the present embodiment, the outer shape of the shaft 5 is not a simple circle but a cross-sectional shape having a plurality of irregularities 16 in the circumferential direction. The shape of the shaft fitting hole is also the same shape as the outer shape of the shaft 5.

  With such a configuration, the contact area between the shaft 5 and the rotor core 4 is increased and the heat transfer is improved, so that the heating time of the rare earth magnet 6 is shortened.

  Other configurations, operations, and effects of the present embodiment are the same as those of the first embodiment. Further, the present embodiment can be applied to the second embodiment.

Embodiment 4 FIG.
FIG. 5 is a diagram showing an image when the contact cross section of the fitting portion in the rotor core 4 of the shaft 5 is viewed microscopically. As shown in FIG. 5, it is better to apply thermal conductive grease 17 to the fitting portion between the shaft 5 and the shaft fitting hole of the rotor iron core 4. Since the surface of the shaft 5 and the rotor iron core 4 has many irregularities 18 microscopically, the true contact area is very small compared to the apparent contact area. By applying the heat conductive grease 17, the gap 19 between the irregularities 18 can be filled.

  With such a configuration, the gap 19 between the projections and recesses 18 of the shaft 5 and the rotor iron core 4 when viewed microscopically is filled with the heat conductive grease 17 to improve the heat transfer, thereby increasing the rare earth magnet 6. Warm time is even shorter.

  In addition, the other structure of this Embodiment, an effect | action, and an effect are the same as that of Embodiment 1-3.

  The present invention is suitable as a built-in magnetizing method for a permanent magnet motor, particularly as a built-in magnetizing method.

DESCRIPTION OF SYMBOLS 1 Rotor 2 Stator 3 Frame 4 Rotor core 5 Shaft 6 Rare earth magnet 7 End plate 8 Bearing 9 Wave washer 10 Stator core 11 Winding 12, 13, 14 Through hole 15 Pipe 16, 18 Concavity and convexity 17 Heat conduction grease 19 Gap 20 Gap 22 Hole 25 Bottom 30 Magnet insertion hole

Claims (7)

An annular rotor core, a plurality of rare earth magnets mounted in a plurality of magnet insertion holes provided on the outer peripheral side of the rotor core, and a shaft that is rotatably supported by being fitted into the shaft fitting hole of the rotor core And a stator having an annular stator iron core disposed opposite to the outside of the rotor with a gap and a winding wound around the stator iron core; A built-in magnetization method of a permanent magnet type motor including a frame for supporting a shaft,
An axial through hole is provided in advance in the shaft, the stator is fixed inside the frame, the rotor is arranged inside the stator, and the rotor is assembled to the frame;
Circulating a heating medium through the through hole to heat the rotor;
Magnetizing the rare earth magnet by passing a current through the winding while the rare earth magnet has reached a predetermined temperature higher than room temperature;
A built-in magnetizing method for a permanent magnet motor. The through hole is a single hole that penetrates the shaft in the axial direction;
2. The built-in magnetizing method for a permanent magnet motor according to claim 1, wherein the heat medium flows in one direction from one end to the other end of the through hole.   The permanent magnet motor built-in magnetization method according to claim 2, wherein the shaft passes through the frame. The through hole is composed of a pair of holes penetrating the shaft in the axial direction,
The mouths of the pair of holes at one end of the shaft are connected by a pipe,
The heat medium flowing in from one of the pair of holes at the other end of the shaft flows through one of the pair of holes, the pipe, and the other of the pair of holes, and the pair at the other end of the shaft. 2. The built-in magnetizing method for a permanent magnet motor according to claim 1, wherein the second magnet flows out from the other opening of the hole.   5. The built-in magnetization method for a permanent magnet motor according to claim 4, wherein one end of the shaft on the side to which the pipe is connected is disposed in the frame.   The built-in magnetization method for a permanent magnet motor according to any one of claims 1 to 5, wherein the outer shape of the shaft is a shape having a plurality of irregularities in the circumferential direction.   The permanent magnet motor according to any one of claims 1 to 6, wherein thermally conductive grease is applied to a fitting portion between the shaft and a shaft fitting hole of the rotor iron core. Magnetization method.

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