JP2000278895A - Rotor of motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To install skew to reduce cogging torque and acoustic vibration by changing the positions of magnetic flux shielding sections continuously with respect to the axis along with core elements are stacked to form the magnetic flux shielding sections aslant axially. SOLUTION: A pair of flux barriers (magnetic flux shielding section) 15, 16 which do not transmit magnetic flux are formed in the peripheral part of a rotor core outside in the circumferential direction of each permanent magnet 14. Each of the magnetic flux shielding sections 15, 16 consists of a first barrier section 15a, 16a which changes its position nearly in the diametric direction (the barrier position varies in the circumferential direction) and second barrier sections 15b, 16b which are fixed adjacent to an end face in the circumferential direction of the permanent magnet 14. The second barrier sections 15b, 16b are extended parallelly with respect to the axial direction in which silicon steel plates 11 are stacked just as the permanent magnets 14. However, the first barrier sections 15a, 16a are changed in their positions continuously in one direction from one end face of the rotor core 12 to the opposite end face with respect to the axial direction. As a result the skew can be installed and cogging torque and acoustic vibration can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a rotor of a motor in which a permanent magnet is embedded in a rotor, and more particularly to a structure in which a so-called flux barrier is provided with skew (inclination) to reduce cogging torque. is there.

[0002]

2. Description of the Related Art As a magnet type synchronous motor (electric motor), there is an IPM motor (embedded magnet type motor) having a permanent magnet embedded in a rotor. Since this motor has features of high efficiency, downsizing, and high rotation, it is currently widely used as a motor suitable for electric vehicles and the like.

[0003] However, in a motor using such a permanent magnet, the attraction force between the stator and the rotor fluctuates in accordance with the reluctance change due to the iron core, and this fluctuation causes a change in angular velocity called cogging torque or torque ripple. A periodic torque fluctuation (hereinafter referred to as cogging torque) occurs. This cogging torque impairs the smoothness of rotation and causes vibration and abnormal noise.

[0004] For this reason, various devices have been conventionally devised to reduce cogging torque. One of them is to provide a skew (inclination) for the magnetic poles (permanent magnets) of the magnet rotor (for example, JP-A-63-140645). Japanese Patent Application Laid-Open (JP-A) No. 5-168181 discloses a technique in which the magnetizing direction of a permanent magnet is inclined to bring about a skew effect on a rotor.

[0005]

However, in the method of providing skew on the magnetic poles of the magnet rotor,
For example, it is necessary to divide the laminated rotor core in the laminating direction together with the permanent magnets, insert the permanent magnets into the divided rotor cores, and then attach the permanent magnets to the shaft in a stepwise manner by a certain angle, thereby increasing the number of work steps. However, there is a problem that the labor and time required for the production increase, leading to an increase in cost. In addition, the method of making the magnetizing direction of the permanent magnet oblique to have a skew effect also requires a special process for making the magnetizing direction oblique, which also requires time and effort for manufacturing. is there.

SUMMARY OF THE INVENTION The present invention has been made in view of such problems of the prior art, and has an electric motor that requires a small number of work steps, is easy to manufacture, is inexpensive, and can reduce cogging torque and sound vibration. The object of the present invention is to provide a rotor.

[0007]

The above object of the present invention is achieved by the following means.

(1) In the rotor of the electric motor according to the present invention, a permanent magnet is arranged inside a rotor core formed by laminating cores alone in an axial direction, and a magnetic flux blocking portion is provided outside the permanent magnet in a circumferential direction. In the rotor of the electric motor, the position of the magnetic flux interrupting portion is continuously changed in the axial direction.

(2) The position of the magnetic flux interrupting portion continuously changes in one direction from one end face of the rotor core to the opposite end face in the axial direction.

(3) The position of the magnetic flux interrupting portion continuously changes symmetrically from the axial center position of the rotor core toward both end faces of the rotor core with respect to the axial direction.

(4) In another rotor of the electric motor according to the present invention, a permanent magnet is arranged inside a rotor core formed by laminating cores alone in an axial direction, and a magnetic flux interrupting portion is provided outside the permanent magnet in a circumferential direction. Wherein the position of the magnetic flux interrupting portion changes stepwise in the axial direction.

(5) The position of the magnetic flux interrupting portion changes stepwise in one direction from one end face of the rotor core to the opposite end face with respect to the axial direction.

(6) The position of the magnetic flux interrupting portion is repeatedly changed stepwise in the axial direction.

(7) The position of the magnetic flux blocking portion is changed in the circumferential direction.

(8) The position of the magnetic flux interrupting part moves in parallel in the width direction of the permanent magnet.

(9) The permanent magnet is a plate-like magnet.

(10) The magnetic flux blocking portion is a through hole.

(11) The permanent magnet is a fan-shaped magnet, and the core alone has an arc-shaped magnet insertion hole whose circumferential length is longer than the fan-shaped magnet. The blocking portion is a gap formed when the permanent magnet is inserted into the magnet insertion hole after the cores are stacked while changing the position of the magnet insertion hole in the circumferential direction.

[0019]

According to the present invention, the magnetic flux interrupting portion is formed obliquely with respect to the axial direction so that the position of the magnetic flux interrupting portion changes continuously or stepwise with respect to the axial direction in which the cores are laminated. Therefore, the magnetic flux generated by the permanent magnet becomes oblique with respect to the axial direction, so that the skew can be provided without disposing the permanent magnet itself or the magnetizing direction of the magnet as in the related art, Cogging torque and sound vibration can be reduced. In addition, ordinary operations are sufficient for operations other than changing the position of the magnetic flux interrupting portion, so that the number of operation steps is smaller than in the conventional art, the production is easy, and the cost is low.

In particular, when the position of the magnetic flux interrupting portion continuously and symmetrically changes from the axial center position of the rotor core toward both end faces of the rotor core, the magnetic flux interrupting portion is positioned at the axial center position of the rotor core. , No axial load acting in the axial direction is generated.

Further, when the position of the magnetic flux interrupting portion is repeatedly changed stepwise in the axial direction, the thrust load acting in the axial direction is reduced.

Further, since a plate-shaped or fan-shaped magnet can be used as the permanent magnet, it is easy to manufacture and inexpensive from this point as well.

When the magnetic flux blocking portion is a part of a through hole or a magnet insertion hole, it is sufficient to prepare a predetermined die for punching, and the operation is simple.

[0024]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a perspective view showing an example of a rotor of a motor of the present invention.

This motor is a four-pole (two-pole pair) IPM motor (embedded magnet type motor) in which four permanent magnets are embedded in the rotor 10. The rotor 10 is made of a thin (for example, 0.5 mm thick) circular silicon steel plate (core unit) 11
Core 12 formed by laminating a plurality of sheets in the axial direction
A motor shaft (not shown) press-fitted into a shaft hole 13 at the center of the rotor core 12;
2 and four permanent magnets 14 arranged at equal intervals in the circumferential direction of the outer peripheral portion. As the permanent magnet 14, an ordinary plate magnet which is easy to manufacture and inexpensive is used.

Further, a pair of flux barriers (magnetic flux blocking portions) 15 and 16 that do not allow magnetic flux to pass therethrough are provided on the outer periphery of the rotor core on the outer side in the circumferential direction of each permanent magnet 14. Here, each of the flux barriers 15, 16 is provided on the first barrier portions 15 a, 16 a whose position is substantially variable in the radial direction (as will be described later, the barrier position changes in the circumferential direction) and on the circumferential end surfaces of the permanent magnets 14. An adjacent position-fixed second barrier portion 15b,
16b. 2nd barrier part 15b, 16b
Extends in a direction parallel to the axial direction in which the silicon steel plates 11 are laminated, like the permanent magnet 14, but the first barrier portion 15
The positions of a and 16a continuously change in one direction from one end face of the rotor core 12 to the opposite end face in the axial direction. The flux barriers 15 and 16 are through holes, and as described later, particularly the second barrier portions 15b and 16b.
The through hole 16b is punched out integrally with the magnet insertion hole 17 for inserting the permanent magnet 14 by using a common mold.
In the longitudinal direction (that is, the laminating direction or the axial direction).

FIG. 2 is a drawing showing the shape of the flux barriers 15, 16 for each process. Here, (A) shows the basic die-cutting shape, (B) shows the barrier die-cutting shape, and (C) shows the corresponding magnet shape.

In this embodiment, the flux barriers 15,
16 (especially, the first barrier portions 15a, 16a) continuously changes in one direction from one end face of the rotor core 12 to the opposite end face in the axial direction while changing in the circumferential direction. .

In this case, first, the basic die-cut shape is shown in FIG.
As shown in (A), the rectangular magnet insertion hole 17 and the second barrier portions (through holes) 15b, 16b adjacent to the circumferential end face of the magnet insertion hole 17 are integrally formed by one common mold. It is formed by punching. This basic die-cutting shape is realized in the same manner in common for all the silicon steel sheets 11 to be laminated. In order to increase the efficiency of the work, it is preferable to arrange the four dies at predetermined positions so that one punching operation may be performed for each sheet or for a plurality of sheets.

Next, as shown in FIG. 2 (B), the barrier die-cut shape is a substantially radial first barrier portion (through hole) 15.
a and 16a are formed by punching with a single mold. At this time, one of the silicon steel plates 11 and the mold is rotated so that the barrier position changes in the circumferential direction (A direction in this example) for each of the silicon steel plates 11 to be laminated, and the barrier position changes relatively by one. All the sheets (N
), Ie, from the silicon steel plate 11-1 on one end of the rotor core 12 to the silicon steel plate 11-N on the other end.
Punch through. At this time, the fixed angle rotated one by one is preferably the rotor core 12
Of the stator (not shown) from one end face (silicon steel sheet 11-1) to the other end face (silicon steel sheet 11-N). Accordingly, the positions of the first barrier portions 15a and 16a continuously change in one direction from one end face of the rotor core 12 to the opposite end face in the axial direction while changing in the circumferential direction. The skew of the flux barriers 15, 16 (especially, the first barrier portions 15a, 16a) is formed as shown by broken lines in FIG. Also in this case, in order to increase the efficiency of the operation, it is preferable that eight (= 2 × 4) dies are arranged at predetermined positions so that one punching operation can be performed for each sheet. .

At this time, as the permanent magnet 14, as shown in FIG. 2C, an ordinary plate magnet which is easy to manufacture and inexpensive can be used.

On the other hand, although not shown, a stator is arranged around the rotor 10, a plurality of teeth are formed on the stator so as to face the rotor 10, and slots are formed between the teeth. A coil is inserted into the slot. In this manner, a rotating magnetic field is generated by passing a current through the coil wound around the stator, and a repulsive force and an attractive force are generated between the stator and the rotor 10 by the rotating magnetic field, so that the rotor 10 rotates. . The torque generated at this time is the magnet torque caused by the repulsion and attraction of the stator coil and the permanent magnet 12 of the rotor 10, and the torque generated by the stator coil and the iron (rotor core 1
1) and the reluctance torque generated by the attraction.

The method of laminating the rotor cores, in other words, the method of providing the skew with respect to the flux barrier is not limited to the embodiment shown in FIG. 1, but various other embodiments are conceivable. FIG. 3 shows three more embodiments as examples. Here, the shape of the flux barrier is the same as that shown in FIGS. 1 and 2. Further, common members are denoted by the same reference numerals.

(Embodiment 2) The rotor 10a shown in FIG.
Then, the positions of the flux barriers 15, 16 (particularly, the first barrier portions 15a, 16a) change stepwise in one direction from one end face of the rotor core 12a to the opposite end face with respect to the axial direction while changing in the circumferential direction. Is changing. Here, for example, the two stages are shifted by one slot of the stator (not shown). The boundary positions of the stages are preferably
This is the axial center position M of the rotor core 12a. In this case, the barrier die-cutting shape punches out the silicon steel sheets 11 of the total number to be laminated while shifting in the direction A by a certain angle each time the stage changes (see FIG. 2). This allows
A skew is formed on the stacked rotor cores 12a as indicated by broken lines in FIG. In the case of this rotor core laminating method, the number of changing stages may be three or more.

(Embodiment 3) The rotor 10b shown in FIG.
Then, the positions of the flux barriers 15, 16 (especially, the first barrier portions 15a, 16a) change in the circumferential direction from the axial center position M of the rotor core 12b to the both end surfaces of the rotor core 12b with respect to the axial direction. And continuously changing symmetrically. Again, preferably, the amount of displacement in the axial direction is one slot of the stator (not shown). In this case, the barrier die-cut shape is shifted in the direction A by a constant angle for each sheet up to the center position M.
After passing through the center position M, the silicon steel sheets 11 are punched out for all the sheets to be laminated while being shifted in the opposite direction B by a constant angle for each sheet (see FIG. 2). As a result, a skew as shown by a broken line in FIG.

When such a lamination method (skew method) is employed, the flux barriers 15, 16
Since the (first barrier portions 15a, 16a) are symmetrical with respect to the axial center position M of the rotor core 12b, there is an advantage that no axial thrust load is generated.

(Embodiment 4) The rotor 10c shown in FIG.
In the example, the positions of the flux barriers 15, 16 (especially, the first barrier portions 15a, 16a) are repeatedly changed stepwise in the axial direction while changing in the circumferential direction. Here, for example, it changes twice in two stages for one slot of a stator (not shown). In the barrier die-cutting shape in this case, the silicon steel plates 11 of the total number to be laminated are punched out while being shifted in the direction A by a certain angle every time the stage is changed for each repeating unit (see FIG. 2). As a result, a skew as shown by a broken line in FIG. In the case of this rotor core laminating method, the number of changing stages may be three or more, and the number of repetitions may be three or more.

When such a lamination method (skew method) is employed, there is an advantage that the thrust load acting on the rotor 10c in the axial direction is reduced.

(Embodiment 5) FIG. 4 is a view showing another example of the shape of the flux barrier for each process. Here, as in FIG. 2, FIG. 2A shows the basic die cut shape, FIG. 2B shows the barrier die cut shape, and FIG. 2C shows the corresponding magnet shape. In addition, members common to FIGS. 1 to 3 are denoted by the same reference numerals.

In this embodiment, the flux barrier 25,
Reference numeral 26 has an L-shape, and its position is translated in the width direction of the permanent magnet 14. Although FIG. 4B shows a case where the rotor core laminating method (skew method) shown in FIG. 1 is applied, the present invention is not limited to this, and is shown in FIGS. 3A to 3C. Of course, the method is also applicable.

In this case, first, the basic die-cut shape is as shown in FIG.
As shown in (A), the rectangular magnet insertion hole 27 is formed by punching out with one mold. As shown in FIG.
This corresponds to the magnet insertion hole 17 in FIG. The basic die-cutting shape is the same as that of the silicon steel sheets 11a
Are commonly implemented in the same manner. As in the case shown in FIG. 2, in order to improve the work efficiency, the four dies are arranged at predetermined positions so that one punching operation can be performed for each sheet or a plurality of sheets at once. Is preferred.

Next, as shown in FIG. 4B, the barrier die-cut shape is formed by punching out the L-shaped flux barriers 25 and 26 with one die. At this time, while either the silicon steel plate 11a or the mold is moved in parallel and relatively shifted so that the barrier position moves parallel to the permanent magnet 14 (in this example, the direction C), the total number of sheets to be stacked ( N
) Of the rotor core, that is, from the silicon steel plate 11a-1 on one end surface of the rotor core to the silicon steel plate 11a on the other end surface.
Punch up to -N. In this case, as described above, the rotor core laminating method (skew method) in various modes as shown in FIG. 1 and FIGS. The barrier punching operation according to the mode will be performed.

Also at this time, the permanent magnet 14 is
As shown in (C), an ordinary plate magnet which is easy to manufacture and inexpensive can be used.

(Embodiment 6) FIG. 5 is a drawing showing still another example of the shape of the flux barrier by process. Here, as in FIGS. 2 and 4, FIG. 2A shows the basic die cut shape, FIG. 2B shows the barrier die cut shape, and FIG. 2C shows the corresponding magnet shape. 1 to 4
The same reference numerals are given to members in common with.

In the present embodiment, a flux barrier is formed using a magnet insertion hole, and the flux barrier is skewed by changing the position of the magnet insertion hole. That is, as shown in FIG. 5C, a fan-shaped magnet 34 is used as the permanent magnet, and each silicon steel plate 11b is used.
Has an arc-shaped magnet insertion hole 37 whose circumferential length is longer than the sector magnet 34. The flux barrier is a gap formed when the permanent magnet 34 is inserted into the magnet insertion hole 37 after laminating the silicon steel plates 11b having the magnet insertion hole 37 while changing the position of the magnet insertion hole 37 in the circumferential direction. Therefore, no flux barrier type is required. The permanent magnet 34 inserted is fixed after lamination.
The gap (functioning as a flux barrier) formed when the magnet is inserted is filled with a predetermined resin (for example, a heat-resistant epoxy resin). FIG. 5B shows a case where the rotor core laminating method (skew method) shown in FIG. 1 is applied. However, the present invention is not limited to this, and it is needless to say that FIGS. The method shown in FIG.

In this case, first, the basic die-cut shape is as shown in FIG.
As shown in (A), the arc-shaped magnet insertion hole 37 whose circumferential length is longer than the sector magnet 34 is formed by punching with one mold. This basic die-cutting shape is realized in the same manner in common for all the silicon steel sheets 11b to be laminated. As in the case of FIGS. 2 and 4, in order to improve the work efficiency, four punches are arranged at predetermined positions, and only one punching operation may be performed for each sheet or for a plurality of sheets. It is preferable to do so.

Next, as shown in FIG. 5 (B), the total number (N) of the silicon steel plates 11 in which the magnet insertion holes 37 are formed are shown.
b are sequentially rotated (in the E direction in this example) from the silicon steel plate 11b-1 on one end surface of the rotor core to the silicon steel plate 11b-N on the other end surface of the rotor core. In this case, as described above, in this case as well, FIG. 1 and FIGS.
Since the rotor core laminating method (skew method) of various modes as shown in FIG.

At this time, as described above, the permanent magnet 34
Can use a fan-shaped magnet as shown in FIG. 4C, and it is easy to manufacture and inexpensive.

Therefore, according to each of the above embodiments, the flux barriers 14, 15 (especially, 14a, 15
a); The positions of 25, 26; 35, 36 are changed continuously or stepwise in the axial direction, and these flux barriers are formed obliquely to the axial direction.
The magnetic flux generated by the permanent magnets 14 and 34 becomes oblique with respect to the axial direction, and skew can be provided without disposing the permanent magnets themselves or making the magnetizing direction of the magnets oblique as in the related art. Cogging torque and sound vibration (generation of vibration and abnormal noise) are reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a rotor of an electric motor of the present invention.

FIG. 2 is a view showing a shape of a flux barrier of FIG. 1 for each process.

FIG. 3 is a perspective view corresponding to FIG. 1, showing another rotor core laminating method.

FIG. 4 is a view showing another example of the shape of the flux barrier for each process.

FIG. 5 is a view showing another example of the shape of the flux barrier for each process.

[Explanation of symbols]

10, 10a, 10b, 10c: rotor, 11, 11a, 11b: silicon steel plate (core alone) 12, 12a, 12b, 12c: rotor core, 14, 34: permanent magnet, 15, 16, 25, 26, 35, 36: flux barrier (magnetic flux cut-off part)

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yuka Yoshimura 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. F-term (reference) 5H622 AA02 CA02 CA07 CA10 CA13 CB04 CB05 PP03 PP10 PP11 QB03

Claims (11)

[Claims] 1. A rotor for an electric motor comprising: a rotor core formed by laminating cores alone in an axial direction; a permanent magnet disposed inside a rotor core; and a magnetic flux blocking portion provided on a circumferentially outer side of the permanent magnet. The position of a part changes continuously with respect to an axial direction, The rotor of an electric motor characterized by the above-mentioned. 2. The rotor according to claim 1, wherein the position of the magnetic flux interrupting portion continuously changes in one direction from one end face of the rotor core to the opposite end face in the axial direction. Electric motor rotor. 3. The rotor according to claim 1, wherein a position of the magnetic flux blocking portion continuously changes symmetrically from an axial center position of the rotor core toward both end surfaces of the rotor core with respect to the axial direction. Item 2. A rotor for an electric motor according to item 1. 4. A rotor for an electric motor in which permanent magnets are arranged inside a rotor core formed by laminating cores alone in an axial direction, and a magnetic flux interrupting portion is provided on the outer side in the circumferential direction of the permanent magnets. The position of a part changes stepwise with respect to an axial direction, The rotor of an electric motor characterized by the above-mentioned. 5. The position of the magnetic flux cut-off portion changes stepwise in one direction from one end face of the rotor core to the opposite end face with respect to the axial direction. Electric motor rotor. 6. The rotor for an electric motor according to claim 1, wherein the position of the magnetic flux cut-off portion repeatedly changes stepwise in the axial direction. 7. The electric motor rotor according to claim 1, wherein the position of the magnetic flux interrupting portion changes in a circumferential direction. 8. The apparatus according to claim 1, wherein the position of the magnetic flux blocking portion is moved in parallel in a width direction of the permanent magnet.
Or the rotor of the electric motor according to 4. 9. The motor rotor according to claim 7, wherein the permanent magnet is a plate-shaped magnet. 10. The electric motor rotor according to claim 7, wherein the magnetic flux blocking portion is a through hole. 11. The permanent magnet is a fan-shaped magnet, and the core unit has an arc-shaped magnet insertion hole whose circumferential length is longer than the fan-shaped magnet, The portion is a gap formed when the permanent magnet is inserted into the magnet insertion hole after the cores are stacked while changing the position of the magnet insertion hole in the circumferential direction, and the core is alone. Electric motor rotor.