JP2008017645A - Permanent magnet embedded motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small, high output and high efficiency permanent magnet embedded motor by providing a second rotor core where a second permanent magnet is magnetized axially so that the same magnetic pole as that of a first rotor core is located on the rotor core side on the end face side of the first rotor core having a first permanent magnet opposing the stator core through an air gap, thereby eliminating an influence of magnetic saturation on the outer circumference of the rotor at an overhang portion. <P>SOLUTION: A permanent magnet embedded motor 1 comprising a stator 2 having an annular yoke and a plurality of teeth formed radially at an interval in the circumferential direction and becoming wiring slots, and a rotor opposing the stator 2 through a small air gap and generating a field with a permanent magnet embedded in the stator core held to rotate freely is further provided with a second rotor 6, having second permanent magnets 7 magnetized in the axial direction so that the same magnetic pole as that on the outer circumference of the first rotor is located on the first rotor core side on the end face side of the first rotor core 4 having first permanent magnets 5 opposing the stator core through an air gap. The second permanent magnet 7 is arranged to substantially oppose the first permanent magnet 5 and the rotor core on the outer circumferential side thereof. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electric motor that is required to be small and highly efficient, such as a compressor, an electric vehicle, a hybrid vehicle, and a fuel cell vehicle, which require a small and highly efficient characteristic, particularly in an embedded permanent magnet electric motor.

  In recent years, awareness of coexistence with the global environment and energy saving has increased, and electric motors installed in electric devices such as compressors used in air conditioners and refrigerators, electric motors installed in electric vehicles, hybrid vehicles, fuel cell vehicles, etc. Even small size and high efficiency are required.

  Generally, the stator winding axial length L2 of a motor having a stator winding arranged in a stator and having a rotor in the radial direction via a magnetic gap is effective as a stator core axial length L1 as a magnetic path. In addition, the length of the stator winding end, that is, the so-called coil end height is required. On the other hand, the rotor core axial length of the rotor without the stator winding is a portion that is effective as a magnetic path opposite to the stator core via the magnetic gap, and is the axial direction of the stator core and the rotor core. The length is almost equal. Therefore, the total length L2 of the stator tends to be longer than the total length of the rotor.

  It is effective to increase the magnetic flux of the permanent magnet interlinked from the rotor to the stator to increase the torque of the electric motor using the permanent magnet, and effectively use the space generated by the difference between the total length L2 of the stator and the total length of the rotor. If it can be increased, the motor can be shortened accordingly, and a small high-efficiency motor can be realized.

  Reference numeral 104 denotes a permanent magnet. Reference numerals 110a and 110b denote overhang portions, which overhang at both ends of the stator core axial length L1. Reference numeral 109 denotes a stator winding. The length of the rotor core in the axial direction is longer than the axial length L2 of the stator core, and the axial length of the permanent magnet also overhangs, thereby increasing the magnetic flux and increasing torque (for example, Patent Document 1). reference).

FIG. 8 shows a perspective view and a longitudinal sectional view of a rotor of a conventional permanent magnet motor. The main permanent magnet 6-4 oriented in the axial direction perpendicular to the rotating shaft 1A and the auxiliary permanent magnet 20-4 arranged on the end surface of the main permanent magnet and oriented in the rotating shaft direction are used to generate the end magnetic flux of the main permanent magnet. By repelling, the leakage magnetic flux is reduced, and the effective magnetic flux is increased to reduce the size (for example, see Patent Document 2).
JP 2000-116044 A JP 59-144350 A

  FIG. 7 is a diagram illustrating an example of the effective magnetic flux and the overhang length of the permanent magnet motor. The effective magnetic flux can be increased by making the axial length of the rotor core longer than the axial length of the stator core. However, if the overhang is a certain length, the magnetic saturation of the outer periphery of the rotor core As a result, the effective magnetic flux amount is saturated, and even if the amount of magnet used is increased, the torque cannot be increased, and the motor cannot be reduced in size.

The present invention solves such a conventional problem, and a first rotor is provided on an end face side of a first rotor core having a first permanent magnet facing the stator core via a gap. The outer periphery of the rotor core in the overhang portion is provided by having a second rotor core in which a second permanent magnet, which is magnetized in the axial direction so that the same magnetic pole as that of the iron core is located on the first rotor core side, is disposed. It is an object of the present invention to provide a permanent magnet embedded type electric motor that eliminates the influence of magnetic saturation in the section and is small and has high output and high efficiency.

  In order to solve the above-described problems, the present invention provides a stator in which a plurality of teeth are radially formed with a circumferential interval between an annular yoke and a winding groove, and a small gap between the stator and the stator. In a motor provided with a rotor that generates a field with a permanent magnet embedded in a rotor core that is opposed and rotatably supported, a first permanent that faces the stator core via a gap A second permanent magnet that is magnetized in the axial direction so that the same magnetic pole as the magnetic pole on the outer periphery of the first rotor is located on the first rotor core side is disposed on the end face side of the first rotor core having a magnet. This is a permanent magnet embedded electric motor having a second rotor.

  Further, the number of poles P, the outer diameter D of the rotor, and the axial length A of the rotor core without the permanent magnet of the first rotor core satisfy the condition of A ≦ πD / 4P. is there.

  In addition, a magnetic material is disposed on the rotor end face.

  In addition, the same magnetic pole as the magnetic pole of the approximately rotor core is axially attached to the end surface side of the first rotor core having the first permanent magnet facing the stator core via a gap so as to be on the rotor core side. This is characterized in that a non-magnetic material is arranged on the outer periphery of the permanent magnet of the second rotor in which the magnetized second permanent magnet is arranged.

  By the above means, it is possible to eliminate the influence of magnetic saturation on the outer peripheral portion of the rotor core in the overhang portion, and to provide a small permanent magnet with a high output and high efficiency.

According to the first aspect of the present invention, the second rotor core overhanging on the end face side of the first rotor core having the permanent magnet facing the stator core via the gap is axially magnetized. By arranging the permanent magnet so as to substantially face the first permanent magnet and the rotor core on the outer peripheral side thereof, the influence of magnetic saturation on the outer periphery of the rotor core in the overhang portion is eliminated, and the small and high output is achieved. An efficient permanent magnet embedded motor can be provided.
According to the invention described in claim 2, the first permanent magnet is arranged so that the center of the magnetic pole is convex toward the center side. The area of the permanent magnet can be widened, the magnetic flux of the end face magnet can be used effectively, a high torque can be realized, and a small, high output and highly efficient embedded permanent magnet electric motor can be provided.
According to the third aspect of the present invention, since the magnetic body is arranged on the end face of the permanent magnet of the overhanging rotor, the amount of magnetic flux can be significantly increased with a slight increase in the axial dimension, and a small high output Thus, a highly efficient permanent magnet embedded motor can be provided.

  According to the invention of claim 4, the number of poles P, the outer diameter D of the rotor, and the axial length A of the first rotor core without permanent magnets is A ≦ πD / 4P. Thus, it is possible to provide a permanent magnet embedded electric motor that is particularly effective for reducing the amount of permanent magnets by effectively utilizing the magnetic flux of the permanent magnets on the end face, and that is small and has high output and high efficiency.

  According to the fifth aspect of the present invention, the nonmagnetic material is disposed and fixed on the outer peripheral portion of the permanent magnet axially magnetized so that the same magnetic pole as that of the overhanging almost rotor core is located on the rotor core side. As a result, it is possible to provide a small and highly efficient permanent magnet embedded type electric motor that can withstand high-speed rotation and has higher output.

  According to the sixth aspect of the present invention, the degree of freedom increases in the shape of the rotor core by using the rotor core by powder sintering, and the magnetic flux of the permanent magnet can be optimally introduced into the stator core. A small-sized, high-output and high-efficiency permanent magnet embedded motor can be provided.

  According to the seventh to eighth aspects of the present invention, a compressor, an electric vehicle, a hybrid vehicle, and a fuel cell vehicle can be contributed to a small size and high efficiency by mounting the permanent magnet embedded type electric motor of the present invention.

  The present invention has a stator in which a plurality of teeth are radially formed at circumferential intervals to be an annular yoke and a winding groove, and is opposed to the stator via a slight gap so as to be rotatable. An end face of a first rotor core having a first permanent magnet opposed to the stator core via a gap, the rotor having a permanent magnet embedded in the held rotor core and generating a magnetic field Embedded with a permanent magnet having a second rotor in which a second permanent magnet, which is magnetized in the axial direction so that the same magnetic pole as the magnetic pole on the outer periphery of the first rotor is located on the first rotor core side, is disposed on the side In the type electric motor, the second permanent magnet is disposed so as to substantially face the first permanent magnet and the rotor core on the outer peripheral side thereof.

  With such a configuration, it is possible to provide a small-sized, high-power and high-efficiency permanent magnet embedded motor that eliminates the influence of magnetic saturation on the outer periphery of the rotor core in the overhang portion.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view of an embedded permanent magnet motor according to a first embodiment of the present invention, and FIG. 2 is a plan view of the embedded permanent magnet motor according to the first embodiment of the present invention. Reference numeral 2 denotes a stator, and a plurality of teeth are radially formed at intervals in the circumferential direction to become an annular yoke and a stator winding groove. In FIG. 2, the stator winding 3 is arranged in the winding groove of the stator. The axial length of the stator is L2, and the axial length of the stator core is L1. The rotor faces the L1 portion of the stator core via a gap, and includes a first rotor core 4 having a first permanent magnet magnetized in the axial cross-section direction, and a first rotor core 4 approximately. The second rotor core 6 is provided with a second permanent magnet 7 that is magnetized in the axial direction so that the same magnetic pole as the first magnetic pole is located on the first rotor core side. A second rotor yoke 8 made of a magnetic material is provided outside the second rotor core. Note that the stator winding 3 and the second rotor yoke 8 are not shown in FIG. 2 for explanation.

  As shown in FIG. 2, the second permanent magnet is disposed on the outer peripheral side core portion of the first permanent magnet at the first rotating core end face. The second permanent magnet is arranged such that the same magnetic pole as the magnetic pole of the first permanent magnet is axially magnetized so as to be on the first rotor core side. Therefore, the magnetic flux of the second permanent magnet flows directly to the outer periphery of the first permanent magnet of the first rotor core, and the outer periphery of the permanent magnet of the rotor core in the overhang portion seen in the conventional example. The effect of saturation of the effective magnetic flux due to magnetic saturation on the side can be eliminated, and a small-sized, high-power and high-efficiency permanent magnet embedded motor can be provided.

  Since the second rotor yoke 8 disposed on the rotor end surface forms a magnetic path with the adjacent second permanent magnet, the axial length of the rotor is slightly longer, but the magnetic flux can be increased. It is valid.

In addition, although a present Example is an example of the embedded magnet type | mold electric motor of a 6 pole V-shaped magnet, the same effect is acquired even when the number of poles differs or a magnet shape becomes a flat plate or a circular arc shape. The larger the axial area on the outer peripheral side of the permanent magnet of the first rotor core, the more effective means. Even if the arrangement of the second permanent magnet partially overlaps the first permanent magnet, the second permanent magnet It suffices if the ratio of the axial cross-sectional area on the outer peripheral side of the permanent magnet of the first rotor core is large with respect to the axial cross-sectional area. The same effect can be obtained even if the second magnet is arranged only on one side, is not limited to all the magnetic poles, is arranged with one or more poles, or is composed of a single permanent magnet magnetized on a plurality of magnetic poles. can get.

  FIG. 3 is a plan view of an embedded permanent magnet electric motor rotor showing another example of the first embodiment of the present invention, and a part of the outer peripheral side of the permanent magnet 5 of the first rotor core. The second permanent magnet 7 is arranged at a position corresponding to the above, and the same effect can be obtained.

FIG. 4 is a schematic perspective view of a permanent magnet for explaining a second embodiment of the present invention. FIG. 4A shows a permanent magnet magnetized in the axial cross-sectional direction used for the first rotor core facing the stator core via a gap.
FIG. 4B shows an axially magnetized permanent magnet used for the second rotor disposed on the end face of the first rotor core. Here, the rotor radius is R, the rotor diameter is D, and the number of poles is P.
In Example 2, the axial direction dimensions of the first rotor core in which no permanent magnet is disposed are indicated by A1 and A2. In this embodiment, more preferable dimensions of A1 and A2 are described.
The following is a schematic calculation of the magnetic flux of the permanent magnet.

  From FIG. 4 (a), when the axial length of the first permanent magnet is A, to maximize the magnetic flux of the permanent magnet, the area indicated by the cross line is maximized, which is proportional to 2RA. To do. That is, it is proportional to DA. However, the thickness of the magnet and the shaft diameter of the rotor are ignored.

On the other hand, from FIG. 4B, in order to maximize the magnetic flux of the second permanent magnet magnetized in the axial direction, the area indicated by the cross line is maximized, which is proportional to πD ^ 2 / 4P. To do. When these two expressions are equal, the magnetic flux of the second permanent magnet is almost equal to the magnetic flux when the first permanent magnet is in the range of the axial dimension A of the first rotor core where no permanent magnet is disposed. Because there are cases,
By setting A ≦ πD / 4P, it is possible to provide a small-sized, high-output and high-efficiency permanent magnet embedded motor with a small amount of magnets.

FIG. 5 is a plan view of a permanent magnet embedded motor rotor showing a third embodiment of the present invention. The top view of the 2nd rotor core is shown, and the 2nd rotor yoke is not illustrated. The first permanent magnet is indicated by a two-dot chain line, 7 is a second permanent magnet by an oblique line, and 10 is a permanent magnet holding ring by a cross line. The permanent magnet holding ring 10 is made of non-magnetic material, and prevents a short circuit of the magnetic flux between adjacent magnetic poles.
The second permanent magnet 7 may be fixed to the first rotor by adhesion or the like, but by using the permanent magnet holding ring 10 as in this embodiment, it can be fixed more firmly, Reliability at high-speed rotation is improved, and a small, high-power and high-efficiency permanent magnet embedded motor that can rotate at higher speed can be provided.

  In addition, the use of a rotor core formed by powder sintering increases the degree of freedom in the shape of the rotor core, and can provide a permanent magnet-embedded electric motor that is smaller and has higher output and higher efficiency.

  Moreover, by mounting the permanent magnet embedded electric motor of the present invention, a compressor, an electric vehicle, a hybrid vehicle, and a fuel cell vehicle can be contributed to small size and high efficiency.

The present invention can realize a small, high-output, high-efficiency electric motor with a simple configuration, and thus is useful as a permanent magnet embedded electric motor for compressors, electric vehicles, hybrid vehicles, fuel cell vehicles, and the like.

1 is a cross-sectional view of a permanent magnet embedded motor showing a first embodiment of the present invention. 1 is a plan view of a permanent magnet embedded motor showing a first embodiment of the present invention. 1 is a plan view of an embedded permanent magnet motor rotor showing another example of the first embodiment of the present invention. (A) is a schematic perspective view of the 1st permanent magnet which shows the 2nd Example of this invention, (b) is a schematic perspective view of the 2nd permanent magnet. Plane view of embedded permanent magnet motor rotor showing a third embodiment of the present invention Vertical section of a conventional permanent magnet embedded motor The figure which shows an example of the effective magnetic flux and overhang part length of a permanent magnet motor A perspective view and a longitudinal sectional view of a conventional permanent magnet type electric motor rotor

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Embedded permanent magnet motor 2 Stator 3 Stator winding 4 1st rotor 5 1st permanent magnet 6 2nd rotor 7 2nd permanent magnet 8 2nd rotor yoke
10 Permanent magnet retaining ring 11 Color made of non-magnetic material

Claims (8)

A stator in which a plurality of teeth are radially formed at circumferential intervals to be an annular yoke and a winding groove, and a rotation that is rotatably held facing the stator through a slight gap. A rotor that generates a field with a permanent magnet embedded in the core of the core, and has a first permanent magnet facing the stator core through a gap, on the end face side of the first rotor core. In a permanent magnet embedded type electric motor having a second rotor in which a second permanent magnet is arranged in the axial direction so that the same magnetic pole as the magnetic pole on the outer periphery of the first rotor is located on the first rotor core side, An embedded permanent magnet electric motor, wherein a second permanent magnet is disposed so as to substantially face the first permanent magnet and the rotor core on the outer peripheral side thereof. 2. The embedded permanent magnet motor according to claim 1, wherein the first permanent magnet is disposed so that the center of the magnetic pole is convex toward the center. 3. A permanent magnet embedded type electric motor according to claim 1, wherein a magnetic body is disposed on an end face of the rotor.
The number of poles P, the outer diameter D of the rotor, and the axial length A of the rotor core without permanent magnets of the first rotor core satisfy the condition of A ≤ πD / 4P. The permanent magnet embedded type electric motor described in 1. The same magnetic pole as the magnetic pole of the rotor core is axially magnetized on the end face side of the first rotor core having the first permanent magnet facing the stator core via a gap so as to be on the rotor core side. The embedded permanent magnet electric motor according to claim 1, wherein a nonmagnetic material is disposed on the outer periphery of the permanent magnet of the second rotor in which the second permanent magnet is disposed.
6. A permanent magnet embedded type electric motor according to claim 1, wherein a rotor core formed by powder sintering is used.
A compressor equipped with the interior permanent magnet motor according to claim 1. An electric vehicle, a hybrid vehicle, and a fuel cell vehicle equipped with the interior permanent magnet motor according to claim 1.

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