JP4631361B2 - Embedded magnet type rotor, manufacturing method thereof, and motor using the embedded magnet type rotor - Google Patents

Description

  The present invention relates to a low iron loss embedded magnet rotor attached to a motor used in various industrial applications and consumer applications, a method for manufacturing the same, and a motor whose efficiency is increased by using the embedded magnet rotor. is there.

  In general, motors are roughly classified into synchronous motors and induction motors. The structure of the rotor (so-called rotor) attached to the motor differs depending on the type of motor. Examples of the rotor of the synchronous motor include a rotor having a permanent magnet embedded therein (hereinafter referred to as an embedded magnet type rotor), a rotor having a permanent magnet attached to the surface thereof (hereinafter referred to as a surface magnet type rotor), and the like.

  In the surface magnet type rotor, the permanent magnet may be peeled off during rotation and the rotation of the rotor may be unstable, and if the peeled permanent magnet is scattered, it causes a serious equipment failure. Therefore, it is necessary to fix the permanent magnet using a glass fiber-containing tape, a stainless steel tube, or the like to prevent the permanent magnet from peeling off.

  On the other hand, in the embedded magnet type rotor, as disclosed in Non-Patent Document 1, a permanent magnet is disposed inside the rotor. Therefore, the permanent magnet does not peel off, and high-speed and stable rotation can be obtained. Moreover, since it is not necessary to use glass fiber-containing tape or stainless steel tubes for fixing the permanent magnets, the distance between the stator (so-called stator) and the rotor (hereinafter referred to as the gap) can be reduced, and the efficiency of the motor is increased. be able to.

  Furthermore, since the embedded magnet type rotor does not use a glass fiber-containing tape or a stainless steel tube, the rotor core is exposed to the gap side. Therefore, there is a difference in inductance between the vertical direction (so-called d-axis) in the central portion of the embedded permanent magnet and the vertical direction (so-called q-axis) in the central portion of the gap between the permanent magnets. A reluctance torque is generated due to such a difference in inductance. Therefore, the embedded magnet type rotor can increase the efficiency of the motor by utilizing the reluctance torque in addition to the torque generated by the permanent magnet.

However, in the embedded magnet type rotor, the magnetic flux distribution in the rotor is complicated and the fluctuation of the magnetic flux is large, so that the iron loss of the rotor increases.
"Design and Control of Embedded Magnet Synchronous Motor" Ohm Corporation 2001

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems and to provide a low iron loss embedded magnet type rotor, a method for manufacturing the same, and a motor with improved efficiency by using the embedded magnet type rotor.

  The present inventors investigated the cause of iron loss in an embedded magnet type rotor. As a result, it has been found that eddy current is generated between the permanent magnet embedded in the rotor and the surface exposed to the gap side (that is, the surface facing the stator), and iron loss occurs. Furthermore, it has been found that eddy current can be reduced by applying plastic strain to the corresponding part. The present invention has been made based on these findings.

That is, the present invention is an embedded magnet type rotor in which a permanent magnet is embedded in a rotor disposed in a motor, and the rotor is formed by stacking iron cores obtained by punching a thin steel plate into the shape of the rotor, A recess for reducing eddy current is provided between the embedded position of the permanent magnet in the iron core and the surface facing the stator and spaced from the embedded position of the permanent magnet, and is calculated by the following equation (1). An embedded magnet type rotor having a deformation region having a plastic strain of 0.1 to 3%.
Record
Plastic strain (%) = 100 x h / t (1)
h: Depth of recess (mm)
t: Iron core thickness (mm)

Further, the present invention provides a method for manufacturing an embedded magnet type rotor in which a permanent magnet is embedded in a rotor disposed in a motor, and a thin steel plate is punched into the shape of the rotor, and the permanent magnet provided inside the rotor is manufactured. A plastic strain of 0.1 to 3% calculated by the following equation (1) by providing a recess for reducing eddy current between the embedding position and the surface facing the stator and in a region separated from the embedding position of the permanent magnet. Is provided, and then the iron core is laminated, and the permanent magnet is embedded in the embedded position.
Record
Plastic strain (%) = 100 x h / t (1)
h: Depth of recess (mm)
t: Iron core thickness (mm)

  Further, the present invention is a motor having the above-described embedded magnet type rotor and a stator disposed around the embedded magnet type rotor.

  ADVANTAGE OF THE INVENTION According to this invention, the iron loss of an embedded magnet type | mold rotor can be reduced. Therefore, the efficiency of the motor can be increased by using the embedded magnet type rotor of the present invention.

  FIG. 1 is a plan view schematically showing an example of an embedded magnet type rotor of the present invention. In manufacturing the embedded magnet type rotor 1, first, punching is performed to process a thin steel plate (for example, an electromagnetic steel plate) into the shape of the iron core 2. Next, a deformation region 5 having plastic strain is provided between the embedded position of the permanent magnet 3 and the surface facing the stator. Although the stator is not shown in FIG. 1, it goes without saying that the stator is disposed outside the rotor.

  In the deformation region 5, plastic strain can be applied by pressing the iron core 2 and providing a recess as shown in FIG. 2. The plastic strain is a value calculated by the following equation (1).

Plastic strain (%) = 100 x h / t (1)
h: Depth of recess (mm)
t: Iron core thickness (mm)
The inventors conducted experiments by varying the amount of plastic strain applied to the deformation region 5 and investigated the relationship between plastic strain and motor efficiency. The motor has a capacity of 750 W, 12 rotor poles and 24 status lots. The material was JIS standard 35A360. The result is as shown in FIG. The motor efficiency is a value calculated by the following equation (2).

Motor efficiency _{(%) = 100 × P out} / P in ··· (2)
P _out : Mechanical output P _in : Electrical input As is clear from FIG. 3, the efficiency of the motor is improved when the plastic strain is in the range of 0.1 to 3%. If the plastic strain is less than 0.1%, the effect of preventing eddy currents is insufficient, so the iron loss increases and the efficiency of the motor decreases. On the other hand, when the plastic strain exceeds 3%, the hysteresis loss increases due to the strain, and the efficiency of the motor decreases. Accordingly, the plastic strain applied to the deformation region 5 needs to satisfy the range of 0.1 to 3%.

  Thus, after providing the deformation region 5 which has a plastic strain of 0.1 to 3% in the iron core 2, the iron core 2 is laminated | stacked, and also the permanent magnet 3 is embed | buried in an embedding position, The embedded magnet type of a low iron loss The rotor 1 can be manufactured. Furthermore, the efficiency of the motor is improved by attaching the embedded magnet type rotor 1 to the motor.

  The deformation region 5 is provided between the embedding position of the permanent magnet 3 and the surface facing the stator, but is preferably provided close to the surface facing the stator.

  FIG. 1 shows an example in which four permanent magnets 3 are arranged. However, in the present invention, the number of permanent magnets 3 embedded in the iron core 2 is not limited. However, it is desirable that the number of permanent magnets 3 is smaller when used for applications requiring high-speed rotation. On the other hand, when used for applications requiring smooth rotation, it is desirable that the number of permanent magnets 3 be large.

  That is, the number of permanent magnets 3 embedded in the iron core 2 may be set as appropriate according to the application of the motor to which the embedded magnet type rotor 1 is attached, the dimensions of the permanent magnets 3 and the like. However, since the combination of the N pole and the S pole must be arranged as a pair, it goes without saying that the number of the permanent magnets 3 is an even number.

[Example 1]
A 0.35 mm thick electromagnetic steel sheet (equivalent to JIS standard 35A300) was punched into the shape of the stator and rotor, and two motors with a capacity of 500 W (12 slots, 4 poles) were produced. As shown in FIG. 1, one of the rotors includes four permanent magnets 3, and further includes four deformation regions 5 having plastic strain between the embedded position of the permanent magnets 3 and the surface facing the stator. An embedded magnet type rotor 1 provided at a location was used. As shown in FIG. 2, the deformation region 5 was subjected to press working and provided with a concave portion to give a plastic strain of 0.8%. The amount of plastic strain is a value calculated by equation (1). This is an invention example.

  On the other hand, as another comparative example, as a comparative example, the deformation region 5 was not provided, and four permanent magnets 3 were arranged to form an embedded magnet type rotor.

  The motors of the inventive example and the comparative example were operated at an output of 500 W, and the efficiency of the motor was investigated. The results are as shown in Table 1. The motor efficiency is the value calculated by equation (2). As is apparent from Table 1, the efficiency of the motor of the invention example was 94.6%, whereas the efficiency of the motor of the comparative example was 93.4%, and the efficiency of the invention example was higher.

[Example 2]
A 0.50 mm thick electromagnetic steel sheet (equivalent to JIS standard 50A470) was punched into the shape of the stator and rotor, and two motors (12 slots, 8 poles) with a capacity of 3 kW were manufactured. One of the rotors is an embedded magnet type rotor in which eight permanent magnets 3 are arranged and eight deformation regions 5 having plastic strain are provided between the embedded position of the permanent magnets 3 and the surface facing the stator. It was set to 1. As shown in FIG. 2, the deformation region 5 was subjected to press work and provided with a recess to give a plastic strain of 2.5%. The amount of plastic strain is a value calculated by equation (1). This is an invention example.

  On the other hand, as another comparative example, as a comparative example, the deformation region 5 was not provided, and eight permanent magnets 3 were arranged to form an embedded magnet type rotor.

  The motors of the inventive example and the comparative example were operated at an output of 3 kW, and the efficiency of the motor was investigated. The results are as shown in Table 2. The motor efficiency is the value calculated by equation (2). As apparent from Table 2, the efficiency of the motor of the invention example was 95.2%, whereas the efficiency of the motor of the comparative example was 94.1%, and the efficiency of the invention example was higher.

It is a top view which shows typically the example of the embedded magnet type | mold rotor of this invention. It is sectional drawing which shows typically the deformation | transformation area | region of the embedded magnet type | mold rotor of this invention. It is a graph which shows the relationship between the plastic strain provided to a deformation | transformation area | region, and the efficiency of a motor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Embedded magnet rotor 2 Iron core 3 Permanent magnet 4 Rotating shaft 5 Deformation area

Claims (3)

An embedded magnet type rotor in which a permanent magnet is embedded in a rotor disposed in a motor, wherein the rotor is formed by laminating an iron core obtained by punching a thin steel plate into the shape of the rotor, and the permanent core in the iron core A recess for reducing eddy current is provided between the magnet embedding position and the surface facing the stator , and in a region separated from the permanent magnet embedding position, and 0.1 to 3% calculated by the following equation (1) : An embedded magnet rotor comprising a deformation region having plastic strain.
Record
Plastic strain (%) = 100 x h / t (1)
h: Depth of recess (mm)
t: Iron core thickness (mm) In a manufacturing method of an embedded magnet type rotor in which a permanent magnet is embedded in a rotor disposed in a motor, a thin steel plate is punched into the shape of the rotor, and the embedded position of the permanent magnet provided in the rotor A recess for reducing eddy current is provided in a region separated from the embedding position of the permanent magnet and between the surface facing the stator and 0.1 to 3% of plastic strain calculated by the following equation (1). Then, the iron core is laminated, and then the permanent magnet is embedded in the embedded position.
Record
Plastic strain (%) = 100 x h / t (1)
h: Depth of recess (mm)
t: Iron core thickness (mm) A motor comprising the embedded magnet type rotor according to claim 1 and a stator disposed around the embedded magnet type rotor.

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