JP5693521B2 - Permanent magnet embedded motor - Google Patents

Description

  The present invention relates to a rotor structure of a magnet embedded type permanent magnet embedded electric motor in which a sintered ferrite magnet is embedded in a rotor core.

  In recent years, with increasing awareness of energy saving, many permanent magnet embedded motors have been proposed that achieve high efficiency by using rare earth magnets with high coercivity for the rotor. However, since rare earth magnets are expensive and increase the cost of the electric motor, a sintered ferrite magnet is used instead of the rare earth magnet in the rotor of a conventional general permanent magnet embedded electric motor. Thus, when a sintered ferrite magnet is used instead of the rare earth magnet, the residual magnetic flux density indicating the magnitude of the magnetic force is reduced to about 1/3. In order to compensate for the decrease in magnetic force, it is necessary to arrange a sintered ferrite magnet having a volume as large as possible on the rotor.

  For example, in a rotor of a permanent magnet embedded motor shown in Patent Document 1 below, a receiving hole for inserting a magnet is provided in the rotor core, and a focal point of magnetic orientation in each magnetic pole of the magnet is provided outside the rotor. It is configured. With this configuration, the gap magnetic flux density between the rotor and the stator is large at the magnetic pole center (the center of the magnet with respect to the circumferential direction of the rotor), and the magnetic pole end (the rotor circumference). Therefore, the distribution is close to a sine wave, and the cogging torque is reduced, and vibration and noise are also reduced.

  Further, in the rotor shown in Patent Document 1 below, the radius of the arc of the curved convex surface formed on the inner diameter side of the magnet is larger than the radius of the arc of the curved convex surface formed on the outer diameter surface side of the magnet. By making it smaller, the compression direction at the time of magnet molding and the direction of the magnetic flux are approximately equal, and a decrease in residual magnetic flux density is suppressed. Thus, since the magnet can be manufactured without reducing the residual magnetic flux density, the problem that the motor efficiency is reduced is solved.

  On the other hand, the permanent magnet embedded type electric motor shown in Patent Document 2 below is an electric motor that uses a torque obtained by adding a magnet torque and a reluctance torque smaller than the magnet torque. Divided into two or more layers in the radial direction, each end of each magnet is configured to extend to a position close to the outer peripheral surface of the rotor, and is generated by q-axis inductance by providing a magnetic flux path between each magnet By increasing the reluctance torque to be generated, the total torque generated by adding the magnet torque and the reluctance torque is maximized, and the demagnetization resistance is improved to achieve higher torque and higher output.

Japanese Patent No. 4598343 (FIG. 2 etc.) Japanese Patent No. 2823817 (FIG. 1 etc.)

  However, the permanent magnet embedded motor shown in Patent Document 1 is formed such that the radial thickness at the magnetic pole central portion is larger than the radial thickness at the magnetic pole end. Due to the extremely small size of the magnetic pole end relative to the size of the magnetic pole center, there is a difference in the shrinkage rate in the sintering process during magnet production, which not only deteriorates the productivity of the magnet, There is a problem that the orientation is deteriorated and sufficient magnetic force cannot be generated. In order to increase the output, it is necessary to increase the size of the ferrite magnet. However, due to the above manufacturing reasons, a large-size ferrite magnet cannot be manufactured, and there is a limit to increasing the output of the motor. .

  The embedded permanent magnet electric motor shown in Patent Document 2 has a structure in which the reluctance torque generated by the q-axis inductance is increased by providing a magnetic flux path between the magnets, resulting in increased torque ripple and vibration and noise. There was a problem that increased.

  The present invention has been made in view of the above, and an object of the present invention is to obtain an embedded permanent magnet electric motor that can suppress vibration and noise by reducing torque ripple while ensuring a sufficient magnetic force.

  In order to solve the above-described problems and achieve the object, the present invention provides a permanent magnet embedded electric motor in which a rotor core formed by laminating a plurality of electromagnetic steel plates is disposed in a stator, Magnets constituting the magnetic poles of the rotor core include a first magnet provided on the outer peripheral side of the rotor core and arranged in a number corresponding to the number of poles in the circumferential direction of the rotor core, and the first magnet Second rotor magnets disposed on the inner diameter side of the rotor core, and the rotor core has a thin outer periphery formed between an outer peripheral surface of the rotor core and an outer diameter side surface of the first magnet. An iron core portion and a magnet interlayer iron core portion formed between the inner diameter side surface of the first magnet and the outer diameter side surface of the second magnet are provided, and the radial thickness of the outer peripheral thin-walled iron core portion is It is 1/3 or less of the thickness in the circumferential direction center part of a 1st magnet, It is characterized by the above-mentioned.

  According to the present invention, since the difference between the thickness of the magnetic pole center portion and the thickness of the magnetic pole end portion of each magnet provided in two layers in the radial direction is reduced, torque ripple is ensured while ensuring a sufficient magnetic force. This reduces the vibration and noise.

FIG. 1 is a sectional view of an embedded permanent magnet electric motor according to an embodiment of the present invention. FIG. 2 is a cross-sectional view centered on a magnet housing hole formed in the rotor core shown in FIG. FIG. 3 is a cross-sectional view of the rotor in a state where magnets are arranged in the magnet accommodation holes shown in FIG. FIG. 4 is a cross-sectional view showing the dimensional relationship of the rotor. FIG. 5 is a diagram showing an example of the magnetic orientation of the magnet. FIG. 6 is a diagram for explaining the distribution of the gap magnetic flux density by the magnet. FIG. 7 is a view showing a modification of the magnet accommodation hole shown in FIG. FIG. 8 is a cross-sectional view of the rotor in a state where magnets are arranged in the magnet accommodation holes shown in FIG.

  Embodiments of an embedded permanent magnet electric 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.
FIG. 1 is a cross-sectional view of a permanent magnet embedded electric motor according to an embodiment of the present invention, and FIG. 2 is a magnet formed on a rotor core (hereinafter simply referred to as “iron core”) 12 shown in FIG. FIG. 3 is a cross-sectional view centering on the housing hole 13, FIG. 3 is a cross-sectional view of the rotor 100 in a state where the magnet 14 is disposed in the magnet housing hole 13 shown in FIG. 2, and FIG. FIG. 5 is a diagram showing an example of the magnetic orientation of the magnet 14, and FIG. 6 is a diagram for explaining the distribution of the gap magnetic flux density by the magnet 14.

  In FIG. 1, an embedded permanent magnet electric motor according to an embodiment of the present invention includes a stator 1 and a rotor 100. The stator 1 includes an annular stator core 2, a plurality of teeth 3 formed at equiangular pitches in the circumferential direction (rotation direction of the rotor 100) in the inner peripheral portion of the stator core 2, and each tooth. 3 and a coil 4 wound around 3. A rotor 100 is rotatably disposed on the inner peripheral side of the stator 1, and a gap 5 is formed between the outer peripheral surface 10 of the rotor 100 and the teeth 3. The stator 1 shown in FIG. 1 is a distributed winding stator as an example, but may be a concentrated winding stator as will be described later.

  FIG. 2 shows the structure of the iron core 12 before the magnet is inserted. The rotor 100 shown in FIG. 2 mainly includes a rotary shaft 11 for transmitting rotational energy and the rotary shaft 11. It has the iron core 12 provided in the outer peripheral part. The iron core 12 and the rotating shaft 11 are connected by, for example, shrink fitting and press fitting.

  The iron core 12 is produced by laminating a plurality of silicon steel plates called iron core punched with a die in the extending direction of the rotating shaft 11 (the back side in FIG. 2). And the outer peripheral surface 10 of the iron core 12 is formed in the cylindrical shape. The iron core 12 is formed with a magnet accommodation hole 13 provided on the same circumference along the circumferential direction. The magnet housing hole 13 is divided in the radial direction to form a two-layer structure, and is disposed on the outer peripheral side of the iron core 12 and formed in a lens shape extending in the circumferential direction. It is comprised by the 2nd magnet accommodation hole 13b arrange | positioned at the rotating shaft side.

  The iron core 12 includes an outer peripheral thin core portion 6 formed between the outer peripheral surface 10 of the iron core 12 and the outer diameter side surface 14a1 of the first magnet 14a, the inner diameter side surface 14a2 of the first magnet 14a, and the second magnet. A magnet interlayer iron core portion 7 formed between the outer diameter side surface 14b1 of 14b is provided. In addition, the hole formed between the rotating shaft 11 and the 2nd magnet accommodation hole 13b is for a refrigerant | coolant and refrigerator oil to pass through.

  In the first magnet housing hole 13a, the outer peripheral surface 10 side surface (outer diameter side surface 13a1) is formed in a curved convex shape along the outer peripheral surface 10, and the rotation shaft 11 side surface (inner diameter side surface 13a2) is the rotation shaft 11. A curved convex shape is formed on the side. That is, the 1st magnet accommodation hole 13a is formed in the lens shape which the both sides of an outer peripheral surface and an internal peripheral surface swell.

The second magnet housing hole 13b is formed in a reverse arc shape whose center of curvature is located on the radially outer side of the rotor 100, and has a surface on the outer peripheral surface 10 side (outer diameter side surface 13b1) and a surface on the rotating shaft 11 side. Both (inner diameter side surface 13b2) are formed in a curved convex shape toward the rotating shaft 11 side. The end portion (circumferential end portion 13b3) of the second magnet housing hole 13b and the outer diameter side surface 13a1 of the first magnet housing hole 13a are located on a concentric circumferential line.

  In FIG. 3, the first magnet accommodation hole 13a described above accommodates the first magnet 14a, and the second magnet accommodation hole 13b accommodates the second magnet 14b. That is, the magnets 14 constituting the magnetic poles of the iron core 12 are separated from the first magnets 14 a arranged in a number corresponding to the number of poles in the circumferential direction of the iron core 12 on the outer peripheral side of the iron core 12 by the magnet interlayer iron core portion 7. And a second magnet 14b disposed on the inner diameter side of the first magnet 14a.

  In FIG. 4, A is the radial thickness at the central portion in the circumferential direction of the first magnet 14a, C is the radial thickness of the outer thin-walled iron core portion 6, and t is the thickness of each electromagnetic steel sheet constituting the iron core 12. ), In consideration of the punchability and magnetic resistance of the iron core punching plate, C is preferably t or more and sufficiently smaller than A (for example, 1/3 or less of A). For example, when t is 0.5 mm and A is 4 mm, C is 0.5 mm or more and 1.3 mm or less.

  Unlike the patent document 2 provided as a magnetic flux path for positively utilizing the reluctance torque, the magnet interlayer iron core portion 7 serves as a reinforcing member that can withstand high-speed driving. Therefore, the thickness dimension in the radial direction of the magnet interlayer core 7 only needs to ensure a minimum dimension that can provide sufficient strength. When the thickness in the radial direction of the magnetic interlayer iron core portion 7 is D, it is desirable that D is a dimension that is equal to or larger than t and sufficiently smaller than A, like the outer thin-walled iron core portion 6. For example, when t is 0.5 mm and A is 4 mm, D is 0.5 mm or more and 1.3 mm or less.

  The outer edge shape of the first magnet 14a is substantially similar to the inner edge shape of the first magnet housing hole 13a. The circumferential end 14a3 of the first magnet 14a is appropriately chamfered to avoid local partial demagnetization. Similarly, the outer edge shape of the second magnet 14b is substantially similar to the inner edge shape of the second magnet housing hole 13b, and the circumferential end 14b3 of the second magnet 14b is chamfered. Each magnet 14 is magnetized so that N poles and S poles alternate with respect to the radial direction of the rotor 100.

  In FIG. 5, the first magnet 14 a is arranged so that the focal point 16 of the magnetic orientation 15 a is on the line connecting the center of the rotor 100 and the magnetic pole central portion of the first magnet 14 a and outside the rotor 100. Magnetized. The second magnet 14b is magnetized so that the focal point 16 of the magnetic orientation 15b is on the line connecting the center of the rotor 100 and the magnetic pole central portion of the second magnet 14b and outside the rotor 100. Has been.

  With this configuration, the gap magnetic flux density by the magnet between the rotor 100 and the stator 1 (gap 5) is large at the magnetic pole center and small at the magnetic pole end. Therefore, the gap magnetic flux density has a distribution close to a sine wave as shown in FIG. 6, and accordingly, the cogging torque is reduced, and vibration and noise are reduced. FIG. 5 shows an example in which the focal points 16 of the respective magnets are located at the same position as an example, but the focal points 16 of the respective magnets only need to be outside the rotor 100. Even if the focal position of the magnetic orientation 15a of the second magnet 14a is different from the focal position of the magnetic orientation 15b of the second magnet 14b, the same effect is obtained. In other words, the focal point 16 of each magnet is not necessarily on the line connecting the center of the rotor 100 and the magnetic pole center of the magnet 14.

  Here, the difference between the permanent magnet embedded electric motor according to the present embodiment and the prior art will be described. In the prior art disclosed in Patent Document 1, the thickness of the magnetic pole end becomes extremely smaller than the thickness of the magnetic pole central portion, and the shrinkage rate of the magnetic pole central portion and the shrinkage of both ends of the magnetic pole in the sintering process at the time of magnet manufacture. The difference with rate increases. Therefore, not only the productivity of the magnet is deteriorated, but also the orientation of the magnet is deteriorated. More specifically, when the shrinkage rate at both ends of the magnetic pole is larger than the shrinkage rate at the center of the magnetic pole in the sintering process at the time of magnet manufacture, the magnetic orientation at both ends of the magnetic pole is changed to the rotor 100 as shown in FIG. Therefore, the gap magnetic flux density becomes large at both the magnetic pole central part and the magnetic pole end part, and the distribution is close to a rectangle. Therefore, it has been difficult for the prior art disclosed in Patent Document 1 to meet the need for further reduction of cogging torque, vibration, and noise.

  On the other hand, in the prior art disclosed in Patent Document 2, since a magnetic flux path is formed between the divided magnets, the reluctance torque generated by the q-axis inductance is increased, and the torque between the magnet torque and the reluctance torque is increased. Due to the torque generated by happiness, there is a problem that torque ripple increases and vibration and noise increase.

  In the rotor 100 according to the present embodiment, each magnet 14 is accommodated in each magnet accommodation hole 13, so that the difference between the thickness of the magnetic pole center portion of each magnet 14 and the thickness of the magnetic pole end portion becomes small. Therefore, the difference between the contraction rate of the magnetic pole central portion and the contraction rate of both end portions of the magnetic pole in the sintering process at the time of magnet manufacture can be reduced. That is, since the compression density at the time of magnet forming becomes small, manufacturing defects such as cracks and chips can be reduced, and the productivity of the magnet 14 can be improved. In addition, since the magnetic orientation at both ends of the magnetic pole can be directed to the vicinity of the line connecting the center of the rotor 100 and the central portion of the magnetic pole, the gap magnetic flux density becomes large at the central portion of the magnetic pole and It becomes smaller and has a distribution close to a sine wave. As a result, it is possible to reduce the cogging torque, vibration, and noise as compared with the prior art.

  Further, in the rotor 100 according to the present embodiment, the first magnet 14a is formed in a curved convex shape on the outer peripheral surface 10 side of the rotor 100, and the thickness C of the outer peripheral thin-walled iron core portion 6 is formed thin. Therefore, the q-axis inductance can be reduced. Therefore, the difference between the q-axis inductance and the d-axis inductance is reduced, and the reluctance torque generated with the same current is reduced. Therefore, compared with the prior art of Patent Document 2, torque ripple caused by an increase in reluctance torque is reduced, and vibration and noise can be reduced.

  In this embodiment, an example in which a distributed winding stator is used as an example of the stator 1 has been described. However, a similar effect can be obtained by using a concentrated winding stator instead of a distributed winding stator. It is done.

  In addition, when an electric motor using a sintered ferrite magnet is used in a low temperature environment (for example, −20 ° C. or lower), when a reverse magnetic field is applied to the sintered ferrite magnet by a current flowing through the coil 4 of the stator 1, the magnet May demagnetize and the motor may become inoperable. This reverse magnetic field is more easily received by the magnet arranged on the outer diameter side of the rotor 100 and demagnetizes the magnet. As such a measure, the first magnet 14a is made of a material having a coercivity higher than that of the second magnet 14b, so that the ratio of being affected by the reverse magnetic field in the first magnet 14a is small. Thus, demagnetization due to application of a reverse magnetic field to the magnet can be suppressed, and the demagnetization resistance is improved. As a result, it is possible to suppress the amount of expensive high coercivity magnets used and to obtain a permanent magnet embedded type electric motor having excellent reliability against demagnetization.

  The demagnetization resistance can also be increased by making the radial thickness A at the circumferential central portion of the first magnet 14a larger than the radial thickness B (see FIG. 4) at the circumferential central portion of the second magnet 14b. It is possible to improve.

  Further, the demagnetization of the sintered ferrite magnet in a low temperature environment is likely to occur when the motor (magnet) is started from a sufficiently cooled state. This is because a large starting current is required when starting the electric motor. As a measure for improving the demagnetization proof strength, when starting the motor in a low temperature environment, it is desirable to start the motor after preheating the motor and raising the temperature of the magnet. As a method for preheating the motor, for example, an iron loss is generated in the iron core 12 by applying a high frequency current of several kHz or more to the coil 4 of the stator 1 using an inverter circuit (not shown). The temperature of the sintered ferrite magnet can be raised.

  Hereinafter, an example in which the shapes of the first magnet housing hole 13a and the first magnet 14a shown in FIGS. 1 to 5 are modified will be described. FIG. 7 is a view showing a modification of the first magnet accommodation hole 13a shown in FIG. 2, and FIG. 8 shows a state in which the magnet 14-1 is arranged in the magnet accommodation hole 13-1 shown in FIG. It is sectional drawing of the rotor 100-1. In the following, the same parts as those in FIGS. 1 to 5 are denoted by the same reference numerals, and the description thereof is omitted.

  The difference between the iron core 12-1 shown in FIG. 7 and the iron core 12 shown in FIG. 2 is the shape of the first magnet housing hole 13a-1, and the outer diameter side surface of the first magnet housing hole 13a-1. A straight cut portion is formed on 13a1-1. Therefore, the 1st magnet accommodation hole 13a-1 has comprised D shape which notched a part of outer periphery. In addition, A is the radial thickness at the central portion in the circumferential direction of the first magnet 14a-1, C is the radial thickness of the outer thin-walled iron core portion 6-1, and t is the thickness of each electromagnetic steel plate constituting the iron core 12. In consideration of punchability and magnetic resistance of the iron core punching plate, C is a dimension not less than t and sufficiently smaller than A (for example, not more than 1/3 of A) like the thickness C shown in FIG. Is desirable.

  In FIG. 8, a first magnet 14a-1 is accommodated in the first magnet accommodation hole 13a-1, and a second magnet 14b is accommodated in the second magnet accommodation hole 13b. The outer edge shape of the first magnet 14a-1 is substantially similar to the inner edge shape of the first magnet housing hole 13a-1. The circumferential end 14a3 of the first magnet 14a-1 is appropriately chamfered to avoid local partial demagnetization. And each magnet (14a-1, 14b) is magnetized so that N pole and S pole may become alternate with respect to the radial direction of the rotor 100-1. The first magnet 14a-1 is magnetized in the same manner as the first magnet 14a shown in FIG.

  Even in the case of such a configuration, the difference between the thickness of the magnetic pole center portion and the thickness of the magnetic pole end portion of each magnet (14a-1, 14b) becomes small as in the rotor 100 shown in FIGS. Therefore, compared with the case where each magnet is integrally molded, the difference between the contraction rate of the magnetic pole center and the contraction rate of both ends of the magnetic pole in the sintering process at the time of magnet manufacture can be reduced, and magnet productivity is increased. It is possible. Moreover, each magnet (14a-1, 14b) is magnetized so that it may become the magnetic orientation similar to the rotor 100 shown by FIGS. 1-5, and the magnetic orientation in a magnetic pole both ends is the rotor 100-1. Can be directed to the vicinity of the line connecting the center of the magnetic pole and the center of the magnetic pole. For this reason, the gap magnetic flux density increases at the magnetic pole central portion and decreases at the magnetic pole end portion, resulting in a distribution close to a sine wave. As a result, it is possible to reduce the cogging torque, vibration, and noise as compared with the prior art. Moreover, since the rotor 100-1 shown by FIG. 7 and FIG. 8 is formed thinly in the outer periphery thin core part 6, q-axis inductance can be made small. Therefore, the reluctance torque generated with the same current is reduced by reducing the difference between the q-axis inductance and the d-axis inductance. Therefore, compared with the prior art of Patent Document 2, torque ripple caused by an increase in reluctance torque is reduced, and vibration and noise can be reduced. Also, since the outer diameter side surface 14a1-1 of the first magnet 14a-1 is provided with a straight cut surface, it is easy to determine the reference during assembly, the motor assembly accuracy is improved, and vibration and noise are reduced. it can.

  As described above, the permanent magnet embedded type electric motor according to the present embodiment is configured by arranging the rotor cores (12, 12-1) formed by stacking a plurality of electromagnetic steel plates in the stator 1. A permanent magnet embedded type electric motor, wherein magnets 14 constituting a magnetic pole of a rotor core are provided on the outer peripheral side of the rotor core and are arranged in a number corresponding to the number of poles in the circumferential direction of the rotor core. Magnets (14a, 14a-1) and second magnets 14b disposed on the inner diameter side of the first magnet, respectively, and the rotor core includes the outer peripheral surface 10 of the rotor core and the first magnet. The outer peripheral thin-walled iron core portion (6, 6-1) formed between the outer diameter side surfaces (14a1, 14a1-1) of the magnet, the inner diameter side surface 14a2 of the first magnet, and the outer diameter side surface 14b1 of the second magnet. Thickness between the outer peripheral thin-walled iron core portion 6 is provided. Is configured to be equal to or less than 1/3 of the thickness A at the circumferential central portion of the first magnet, so that the difference between the thickness of the magnetic pole central portion of each magnet 14 and the thickness of the magnetic pole end portion is reduced. Compared with the case where the magnets 14 are integrally formed, the difference between the contraction rate of the magnetic pole center and the contraction rate of both ends of the magnetic pole in the sintering process at the time of magnet manufacture can be reduced. Can be directed to the vicinity of the center of the rotor 100, so that the gap magnetic flux density increases at the magnetic pole center and decreases at the magnetic pole end, resulting in a distribution close to a sine wave. As a result, it is possible to reduce the cogging torque, vibration, and noise as compared with the prior art. Further, since the thickness C in the radial direction of the outer thin core portion 6 is formed to be 1/3 or less of the thickness A in the central portion in the circumferential direction of the first magnet, the q-axis inductance can be reduced. . Therefore, the difference between the q-axis inductance and the d-axis inductance is reduced, and the reluctance torque generated with the same current is reduced. Therefore, compared with the prior art of Patent Document 2, torque ripple caused by an increase in reluctance torque is reduced, and vibration and noise can be reduced.

  Further, the first magnet 14a according to the present embodiment has a lens shape extending in the circumferential direction, the outer diameter side surface 14a1 is formed in a curved convex shape toward the outer peripheral surface 10 side of the rotor core 12, and the inner diameter side surface 14a2. Is formed in a curved convex shape toward the rotating shaft 11, the second magnet 14 b is formed in a reverse arc shape with the center of curvature positioned radially outward, and both the outer diameter side surface 14 b 1 and the inner diameter side surface 14 b 2 are the rotating shaft 11. Since the circumferential end 14b3 extends to the outer peripheral surface 10 side of the rotor core 12, the center of the arc formed by the outer diameter side surface 14a2 of the first magnet 14a, The center of the arc formed by the outer diameter side surface 14b2 of the second magnet 14b and the center of the magnetic orientation (15a, 15b) of each magnet 14 are in the same direction (outside the rotor 100), and compression during magnet molding The direction and the magnetic flux direction are the same. As a result, since the residual magnetic flux density of the magnet does not decrease, the motor efficiency does not deteriorate.

  Further, the first magnet 14a-1 according to the present embodiment has a D shape with a part of the outer peripheral edge cut out, the outer diameter side surface 14a1-1 is formed flat, and the inner diameter side surface 14a2 is a rotation axis. The second magnet 14b is formed in a reverse arc shape with the center of curvature positioned radially outward, and both the outer diameter side surface 14b1 and the inner diameter side surface 14b2 are curved toward the rotating shaft 11 side. Since it is formed in a convex shape and the circumferential end 14b3 extends to the outer peripheral surface 10 side of the rotor core 12-1, the compression direction and the magnetic flux direction at the time of magnet molding are the same as described above, and at the time of assembly This makes it easy to set the standard, improves the motor assembly accuracy, and reduces vibration and noise.

  Further, in the embedded permanent magnet electric motor according to the present embodiment, the radial thickness at the circumferential central portion of the first magnet (14a1, 14a-1) is A, and the circumferential central of the second magnet 14b is A. When the thickness in the radial direction at the part is B, the thickness in the radial direction of the outer thin core part 6 is C, the thickness in the radial direction of the magnet interlayer core part 7 is D, and the thickness of the electrical steel sheet is t, B < Since the relationship of A, t <C <1 / 3A, t <D <1 / 3A is satisfied, the strength is reduced while maintaining the strength in the outer peripheral thin core 6 and the magnetic interlayer core 7 that can withstand high-speed driving. It is possible to improve the magnetic strength.

  Moreover, since the embedded permanent magnet electric motor according to the embodiment is configured such that the coercive force of the first magnet (14a, 14a-1) is higher than the coercive force of the second magnet 14b, The proportion of the first magnet that is affected by the reverse magnetic field is reduced, demagnetization due to application of the reverse magnetic field to the magnet can be suppressed, and the demagnetization resistance is improved. As a result, it is possible to suppress the amount of expensive high coercivity magnets used and to obtain a permanent magnet embedded type electric motor having excellent reliability against demagnetization.

  The permanent magnet embedded electric motor according to the embodiment of the present invention is an example of the contents of the present invention, and can be combined with another known technique. Of course, it is possible to change and configure such as omitting a part without departing from the scope.

  As described above, the present invention is applicable to an embedded permanent magnet electric motor, and is particularly useful as an invention that can reduce noise and vibration.

DESCRIPTION OF SYMBOLS 1 Stator 2 Stator iron core 3 Teeth 4 Coil 5 Space | gap 6,6-1 Outer peripheral thin core part 7 Magnet interlayer core part 10 Outer peripheral surface 11 Rotating shaft 12, 12-1 Rotor core 13 Magnet accommodation hole 13a, 13a-1 1st magnet accommodation hole 13a1, 13a1-1, 13b1, 14a1, 14a1-1, 14b1 Outer diameter side surface 13a2, 13b2, 14a2, 14b2 Inner diameter side surface 13b Second magnet accommodation hole 13b3, 14a3, 14b3 Circumferential end 14 14-1 Magnet 14a, 14a-1 First magnet 14b Second magnet 15a, 15b Magnetic orientation 16 Focus 100, 100-1 Rotor

Claims (3)

A permanent magnet embedded electric motor in which a rotor core formed by laminating a plurality of electromagnetic steel plates is arranged in a stator,
Magnets constituting the magnetic poles of the rotor core are provided on the outer peripheral side of the rotor core and are arranged in a number corresponding to the number of poles in the circumferential direction of the rotor core, and the first magnet A second magnet disposed on the inner diameter side of the magnet,
In the rotor core,
Between the outer peripheral thin-film core portion formed between the outer peripheral surface of the rotor core and the outer diameter side surface of the first magnet, and between the inner diameter side surface of the first magnet and the outer diameter side surface of the second magnet. And a magnetic interlayer iron core formed on
The first magnet has a lens shape extending in the circumferential direction, an outer diameter side surface is formed in a curved convex shape toward the outer peripheral surface side of the rotor core, and an inner diameter side surface is formed in a curved convex shape toward the rotating shaft side. ,
The second magnet is formed in a reverse arc shape with the center of curvature positioned radially outward, both the outer diameter side surface and the inner diameter side surface are formed in a curved convex shape toward the rotation axis, and the circumferential end portion is rotated. Extending to the outer peripheral side of the core,
The relationship B <A is satisfied, where A is the radial thickness at the circumferential central portion of the first magnet and B is the radial thickness at the circumferential central portion of the second magnet. Permanent magnet embedded motor. A permanent magnet embedded electric motor in which a rotor core formed by laminating a plurality of electromagnetic steel plates is arranged in a stator,
Magnets constituting the magnetic poles of the rotor core are provided on the outer peripheral side of the rotor core and are arranged in a number corresponding to the number of poles in the circumferential direction of the rotor core, and the first magnet A second magnet disposed on the inner diameter side of the magnet,
In the rotor core,
Between the outer peripheral thin-film core portion formed between the outer peripheral surface of the rotor core and the outer diameter side surface of the first magnet, and between the inner diameter side surface of the first magnet and the outer diameter side surface of the second magnet. And a magnetic interlayer iron core formed on
The first magnet has a D-shape in which a part of the outer peripheral edge is notched, the outer diameter side surface is formed flat, the inner diameter side surface is formed in a curved convex shape toward the rotating shaft side,
The second magnet is formed in a reverse arc shape with the center of curvature positioned radially outward, both the outer diameter side surface and the inner diameter side surface are formed in a curved convex shape toward the rotation axis, and the circumferential end portion is rotated. Extending in the outer peripheral direction of the core,
The relationship B <A is satisfied, where A is the radial thickness at the circumferential central portion of the first magnet and B is the radial thickness at the circumferential central portion of the second magnet. Permanent magnet embedded motor. When front radial thickness of Kigai circumferential thin core portion is C, a radial thickness before Ki磁 stone interlayer core portion is D, the thickness of the electromagnetic steel sheet was t,
3. The embedded permanent magnet electric motor according to claim 1, wherein a relationship of t <C <1 / 3A and t <D <1 / 3A is satisfied.

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