JP2004350345A - Permanent magnetic motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a permanent magnet motor in which torque pulsation can be reduced without lowering the torque and low vibration low noise can be realized when the permanent magnet motor is built in an apparatus. <P>SOLUTION: In the permanent magnet motor embedded with magnets, permanent magnet embedding holes 13 are made to penetrate a rotor core 16 laminating stator cores 12 in the axial direction. Permanent magnets 14 corresponding in number to that of P poles are then embedded in the circumferential direction and an air layer region is formed by a slit 15 at the q-axis flux region part of a pole on the outer circumferential side of the permanent magnet 14. Effective quantity of flux intersecting a stator 18 is regulated by the air layer at the q-axis flux region part thus reducing torque pulsation. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a permanent magnet motor having a permanent magnet in a rotor, a compressor equipped with the motor, and various devices such as an air conditioner, a fuel cell or an actuator equipped with the compressor.
[0002]
[Prior art]
FIG. 4 shows a rotor configuration of a conventional electric motor. The rotor 11 of the conventional electric motor is designed so that the magnetic pole iron core on the outer peripheral side of the permanent magnet 14 is widened, the magnetic flux path is enlarged, and a large amount of magnetic flux can pass therethrough (for example, see Patent Document 1).
[0003]
Further, there has been an electric motor in which a plurality of elongated slits are formed in a magnetic pole core on the outer peripheral side of a permanent magnet of a rotor in a normal direction (for example, see Patent Document 2).
[0004]
[Patent Document 1]
JP-A-11-122852 [Patent Document 2]
JP-A-2001-37186 [0005]
[Problems to be solved by the invention]
However, in an electric motor designed to have a wide magnetic pole core on the outer peripheral side of the above-described conventional permanent magnet and to increase a magnetic flux path and allow a large amount of magnetic flux to pass, in order to achieve the maximum torque, the permanent magnet outer peripheral side is required. Is designed so that the q-axis flux region of the magnetic pole is widened, the torque pulsation rate is about 21%. Therefore, when the motor is assembled at a high speed of 3000 r / min or more and 15000 r / min or less after being assembled, the vibration of the 18th and 36th order components of the mechanical rotation speed increases in the case of 6 poles, resulting in noise. Has also been a problem.
[0006]
Further, in the electric motor in which a plurality of elongated slits are formed in the normal direction on the magnetic pole core on the outer peripheral side of the permanent magnet of the rotor, a plurality of elongated slits are formed in the normal direction in order to suppress the above-described noise. However, there is a problem that the maximum torque is reduced by about 13% in order to block the magnetic flux passing through the q axis on the outer peripheral side of the permanent magnet.
[0007]
The present invention has been made in view of such problems, and by providing an air layer region by slits in each magnetic pole on the outer peripheral side of the permanent magnet of the rotor core, reducing torque pulsation without lowering the maximum torque. It is another object of the present invention to provide a motor capable of realizing low vibration and low noise when incorporated in a device.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, the present invention is to provide an air layer region by a slit in a q-axis flux region of each magnetic pole on the outer peripheral side of a permanent magnet of a rotor core.
[0009]
As a result, it is possible to obtain an electric motor capable of reducing torque pulsation without lowering the maximum torque and realizing low vibration and low noise when incorporated in a device.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
An invention according to claim 1 of the present invention is a rotor of an adduction type electric motor that rotates rotatably to the inside diameter of the stator, wherein the rotor has a plurality of holes that accommodate permanent magnets. An air layer region is provided by a slit in the q-axis flux region portion of each magnetic pole on the outer peripheral side of the permanent magnet, which is constituted by a rotor core in which steel plates are stacked, and a plurality of the permanent magnets housed in the rotor core. When the maximum distance in the normal direction from the outermost periphery of the rotor core to the permanent magnet is Lm and the length of the slit in the radial direction is Ls, 0.3Lm <Ls <0.75Lm. It is a permanent magnet motor characterized in that when punching out the rotor core with a mold, it can be punched with high accuracy, reducing torque pulsation while ensuring high reliability at high speed rotation of the rotor. Can .
[0011]
According to a second aspect of the present invention, in the permanent magnet electric motor according to the first aspect, when the number of slots of the stator is S, the center position of the slit in the rotation direction is 360 ° with respect to the center line of the magnetic pole of the permanent magnet. / S is a permanent magnet electric motor characterized by being present in an area within / S, and can reduce torque pulsation without lowering the maximum torque.
[0012]
According to a third aspect of the present invention, in the permanent magnet electric motor according to the first aspect, the maximum distance in the normal direction from the outermost periphery of the rotor core to the permanent magnet is Lm, and the length of the slit in the radial direction is Ls. , 0.3Lm <Ls <0.75Lm, and assuming that the number of slots of the stator is S, the center position of the slit in the rotation direction is within 360 ° / S with respect to the center line of the magnetic pole of the permanent magnet. A permanent magnet electric motor characterized in that the rotor core can be punched with high precision when punching the rotor core with a mold, and the maximum torque can be ensured while ensuring high reliability at high speed rotation of the rotor. Torque pulsation can be reduced without reducing the torque pulsation.
[0013]
According to a fourth aspect of the present invention, there is provided the permanent magnet motor according to any one of the first to third aspects, wherein a cross-sectional shape of the slit is configured by a round hole, and a die is punched. Punches can be easily made to facilitate maintenance.
[0014]
According to a fifth aspect of the present invention, there is provided the permanent magnet motor according to any one of the first to third aspects, wherein a cross-sectional shape of the slit is formed by an elongated hole, thereby achieving the maximum torque. And low vibration and low noise can be easily balanced.
[0015]
According to a sixth aspect of the present invention, there is provided the permanent magnet motor according to any one of the first to third aspects, wherein the slit has a polygonal cross-sectional shape, and achieves the maximum torque. The degree of freedom of design can be widened when balancing low vibration and low noise.
[0016]
According to a seventh aspect of the present invention, there is provided an apparatus equipped with the permanent magnet motor according to any one of the first to sixth aspects, wherein the high-speed apparatus has a high speed of 3000 r / min or more and 15000 r / min or less. , The air conditioner and the fuel cell can have low vibration and low noise.
[0017]
The invention according to claim 8 is a moving body characterized in that the device according to claim 7 moves, and reduces vibration and noise even when an external force acts on the electric motor due to vibration or the like accompanying the movement. Can be realized.
[0018]
【Example】
Hereinafter, specific examples of the present invention will be described with reference to the drawings.
[0019]
(Example 1)
The adduction type permanent magnet motor is mainly composed of a stator and a rotor rotatably held on the inner diameter of the stator via a gap.
[0020]
FIG. 1 shows a configuration of a stator and a rotor of a permanent magnet motor, showing one embodiment of the present invention.
[0021]
As shown in FIG. 1, a stator 18 of a permanent magnet motor includes a yoke 20, a tooth 21, and a slot 19 formed between adjacent teeth, and a plurality of high-permeability thin iron plates are stamped and laminated by a press. In this case, the coil of each phase is inserted into the slot 19 with one coil (not shown) per slot in this case.
[0022]
On the other hand, the rotor 11 of the permanent magnet motor includes a rotor core 16 formed by stamping and laminating a rotor core 12 made of a plurality of high-permeability thin iron plates having a hole 13 for accommodating a permanent magnet 14, and a rotor core 16. , A plurality of permanent magnets 14 housed and held in an axial direction, an end plate (not shown) arranged in the axial direction, a caulking pin 17 for fastening the rotor core 16 and the end plate, and the like.
[0023]
In the illustrated example, the number of pole pairs P of the rotor is 6, and the number of slots S of the stator is 18, but other combinations are also applicable.
[0024]
The rotor has six permanent magnets disposed in permanent magnet embedding holes of the rotor core, and is rotatably held on the inner diameter of the stator via a gap. Generally, in order to achieve the maximum torque if the number of poles and the rotor outer diameter are determined, the width of the permanent magnet is widened and the q-axis flux region of the magnetic pole on the outer peripheral side of the permanent magnet is designed to be wide. In this case, the torque pulsation rate is about 21%. In this embodiment, the torque pulsation can be reduced by about 30% by providing the air layer region by the slit in the q-axis flux region of the outer peripheral magnetic pole of each permanent magnet.
[0025]
Assuming that the maximum distance in the normal direction from the outermost periphery of the rotor core to the permanent magnet is Lm and the length of the slit in the radial direction is Ls, 0.3Lm <Ls <0.75Lm. When the motor is an electric motor, if Ls is 0.3 or less, the amount of magnetic flux flowing along the q-axis and linking the coil does not change, so that torque pulsation does not decrease. On the other hand, if Ls exceeds 0.75, the distance between the permanent magnet and the slit, and the distance between the outer periphery of the rotor and the slit becomes small, so that the die cannot be punched accurately when pressed with a mold, or when the motor is rotated at high speed. Cracks. Ls is preferably 0.4 to 0.5 in order to realize the maximum torque and the low torque pulsation. By doing so, the rotor core can be punched with high precision when punching with a mold, and torque pulsation can be reduced while ensuring high reliability at the time of high-speed rotation of the rotor.
[0026]
Assuming that the number of slots of the stator is S, the center position of the slit in the rotation direction exists in an area within 360 ° / S with respect to the center line of the magnetic pole of the permanent magnet. If it exceeds this range, the effective magnetic flux flowing through the q-axis flux region and flowing into the teeth does not change, so that the torque pulsation does not change. In the present embodiment, the center position in the rotation direction of the slit is made to coincide with the center line of the magnetic pole. By doing so, torque pulsation can be reduced without lowering the maximum torque.
[0027]
FIG. 2 shows the results of torque analysis performed by the permanent magnet motor according to the present embodiment, and shows comparison results depending on the presence or absence of the slit on the outer peripheral portion of the permanent magnet. FIG. 2A shows a comparison result of the torque analysis, and FIG. 2B shows a comparison result of the torque pulsation rate.
[0028]
As is apparent from the figure, if the maximum distance in the normal direction from the outermost periphery of the rotor core to the permanent magnet is Lm and the length of the slit in the radial direction is Ls, then 0.3Lm <Ls <0.75Lm. Assuming that the number of slots of the stator is S, the center position of the slit in the rotation direction is within 360 ° / S with respect to the center line of the magnetic pole of the permanent magnet, so that the average torque is substantially reduced. And torque pulsation can be reduced by about 30%.
[0029]
In the present embodiment, the cross-sectional shape of the slit is set to a round hole, and a punch for punching a die can be easily formed to facilitate maintenance.
[0030]
(Examples 2 and 3)
Next, a second embodiment of the permanent magnet motor of the present invention will be described with reference to FIG. The description of the same components as those in the first embodiment will be omitted, and only different points will be described. In the first embodiment, the cross-sectional shape of the slit is a round hole. FIG. 3A shows the second embodiment, and FIG. 3B shows the third embodiment. A similar effect can be obtained by forming the cross-sectional shape of the slit as a long hole as shown in FIG. Further, it is possible to easily achieve the balance between achieving the maximum torque and reducing the vibration and the noise. By configuring the cross-sectional shape of the slit as a polygon as shown in FIG. 3 (b), it is possible to expand the degree of freedom in designing when achieving the maximum torque and reducing the vibration and noise.
[0031]
The permanent magnet electric motor having the rotor of the present invention realizes low vibration and low noise even in a high-speed rotation driving state of 3000 r / min or more, or when traveling while mounted on a moving body (vibration is generated by traveling). Can be.
[0032]
Devices used in such a situation include an electric compressor mounted on a vehicle, an air conditioner equipped with the compressor, or a blower fan for the air conditioner, a fan for cooling a radiator, and a fan used for an electric vehicle. Fuel cells (electric motors are used for supplying hydrogen and oxygen) and the like, and moving bodies include automobiles, electric bicycles, and vacuum cleaners (used while moving with people).
[0033]
Note that many of the moving objects are driven by a battery. In such a case, the efficiency of the electric motor is high, so that the power consumption of the battery can be reduced.
[0034]
【The invention's effect】
As described above, according to the present invention, torque pulsation can be reduced without reducing the maximum torque. When the rotor core is punched with a mold, the rotor core can be punched with high accuracy, and high reliability can be secured when the rotor rotates at high speed. Further, it is possible to easily achieve the balance between the achievement of the maximum torque and the low vibration and low noise, and it is possible to widen the degree of freedom of design.
[0035]
Further, even if the motor is driven at a high speed of 3000 r / min or more, a motor with low vibration and low noise can be obtained.
[0036]
Further, by mounting the electric motor on a device or a moving body, a moving body with low vibration and low noise can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a stator and a rotor of a motor of the present invention. FIG. 2 is a view showing a comparison result by torque analysis of the motor of the present invention. FIG. FIG. 4 is a sectional view showing a configuration of a rotor of a conventional electric motor.
DESCRIPTION OF SYMBOLS 11 Rotor 12 Rotor core 13 Permanent magnet embedding hole 14 Permanent magnet 15 Slit 16 Rotor core 17 Caulking pin 18 Stator 19 Slot 20 Yoke 21 Teeth 22 Stator core 23 Stator core

Claims (8)

A stator, a rotor of an adduction type electric motor rotatably rotating to the inside diameter of the stator, wherein the rotor has a rotor core in which a plurality of steel plates having holes for accommodating permanent magnets are stacked, A permanent magnet motor, comprising a plurality of permanent magnets and the like housed in a core iron, wherein an air layer region is provided by a slit in a q-axis flux region of each magnetic pole on the outer periphery side of the permanent magnet. Assuming that the maximum distance in the normal direction from the outermost periphery of the slave core to the permanent magnet is Lm, and the length of the slit in the radial direction is Ls, 0.3Lm <Ls <0.75Lm. Electric motor. In the permanent magnet electric motor according to claim 1, when the number of slots of the stator is S, the center position of the slit in the rotation direction is within 360 ° / S with respect to the center line of the magnetic pole of the permanent magnet. A permanent magnet motor. 3. The permanent magnet motor according to claim 1, wherein Lm is the maximum distance in the normal direction from the outermost periphery of the rotor core to the permanent magnet, and Ls is the length of the slit in the radial direction. 75Lm, wherein the number of slots in the stator is S, and the center position of the slit in the rotational direction is within 360 ° / S with respect to the center line of the magnetic pole of the permanent magnet. Permanent magnet motor. The permanent magnet motor according to any one of claims 1 to 3, wherein the cross-sectional shape of the slit is a round hole. The permanent magnet motor according to any one of claims 1 to 3, wherein the slit has a cross-sectional shape formed by an elongated hole. The permanent magnet motor according to any one of claims 1 to 3, wherein the slit has a polygonal cross section. An apparatus comprising the electric motor according to any one of claims 1 to 6. A moving body, wherein the device according to claim 7 moves.

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