JP4451533B2 - Electric motor rotor and method of manufacturing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rotor for an electric motor, and more particularly to an electric motor rotor for reducing eddy currents generated in a plurality of secondary conductors formed in a rotor core and a method for manufacturing the same.
[0002]
[Prior art]
FIG. 12 shows a rotor core of a conventional induction motor, and particularly shows one of a plurality of rotor cores 1,..., 1 constituting the rotor core.
[0003]
As shown in FIG. 12, each of the plurality of rotor cores 1,..., 1 stacked in the axial direction has a plurality of secondary conductor formation holes 2, each having a “slip shape” on its circumference. ..., 2 are drilled at predetermined intervals. After the plurality of rotor cores 1,..., 1 are stacked, the secondary conductor forming holes 2,..., 2 are filled with liquid aluminum, and the aluminum secondary conductor is formed by solidifying the filled aluminum. (Aluminum die cast).
[0004]
In the example of FIG. 12, 22 rod-shaped conductors are embedded as secondary conductors in the rotor core, and both ends in the axial direction are short-circuited by end rings (not shown). After the rotor shaft (not shown) is press-fitted into the shaft hole 6, the rotor core is loosely inserted into a stator core (not shown) provided with a three-phase winding.
[0005]
In the induction motor having the above configuration, when a three-phase alternating current is passed through the stator winding, a rotating magnetic field is formed, and an induced current flows through the secondary conductor. Due to the interaction between this current and the original rotating magnetic field, rotational torque is generated in the rotor.
[0006]
FIG. 13 is a cross-sectional view of one of the secondary conductors 3,..., 3 cut along a plane including the rotation axis. When the illustrated magnetic flux φ passes through the conductor, a circulating current I is generated inside the conductor. To do. Although this circulating current I does not contribute to torque generation (currents having the same magnitude and opposite direction act on magnetic flux in the same direction, the torque is canceled), but Joule loss occurs. There is a problem of causing a reduction in efficiency of the electric motor.
[0007]
On the other hand, Japanese Patent Laid-Open No. 57-28557 discloses an induction motor rotor that reduces harmonic secondary loss by changing the shape of the secondary conductor and improves the efficiency of the motor. .
[0008]
More specifically, a plurality of protrusions are formed in the secondary conductor formation hole of each rotor core, and the protrusions are spirally formed by sequentially laminating each of the plurality of rotor cores. Is arranged. In this rotor, a spiral secondary conductor is formed in the axial direction by aluminum die casting.
[0009]
In this configuration, the harmonic current (secondary current) induced in the upper part of the secondary conductor formation hole flows in a spiral, and the current flow range becomes the entire circumference of the secondary conductor formation hole, and the cross-sectional area increases. The reduction in efficiency is suppressed by reducing the equivalent resistance.
[0010]
[Problems to be solved by the invention]
However, in the rotor of the induction motor disclosed in Japanese Patent Application Laid-Open No. 57-28557, compared with the case where no protrusion is formed, the configuration in which only the path through which the harmonic current flows is changed, and there is a slight loss reduction effect. Was recognized, but there was still room for improvement.
[0011]
The present invention has been made in view of such problems of the prior art, and is inexpensive and reliable that can improve motor efficiency by reducing eddy currents generated in a plurality of secondary conductors. It aims at providing a high rotor and its manufacturing method.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, a rotor for an electric motor according to claim 1 of the present invention includes a plurality of rotor cores laminated in the axial direction and having a plurality of openings for forming a secondary conductor, and A rotor of an electric motor provided with a secondary conductor formed by filling a secondary conductor forming opening with aluminum, and the plurality of openings of each rotor core are arranged at predetermined intervals in the circumferential direction. Each of the plurality of openings formed by a plurality of holes separated by a partition provided in the rotor core, and each of the secondary conductors by a plurality of parts separated by the partition. The angle formed by the center line of the partition part with respect to a line connecting the center of each rotor core and the center of the partition part is different between the rotor cores adjacent in the axial direction, and the secondary Displace the multiple parts of each conductor in the axial direction of the secondary conductor Characterized in that it was.
[0013]
The invention according to claim 2 is characterized in that the axial sectional areas of the plurality of parts are set to be substantially constant.
[0014]
Furthermore, the invention described in claim 3 is characterized in that the dislocation angle of each part is set to an integral multiple of 180 °.
[0015]
The invention described in claim 4 is characterized in that a plurality of permanent magnets are embedded inside the secondary conductor.
[0016]
In the invention according to claim 5, the center line of each of the secondary conductors is inclined with respect to a line connecting the centers of shaft holes formed at the centers of the rotor cores in the axial direction. Features.
[0017]
In the invention according to claim 6, the distance between adjacent openings is τ1, the width of the partition is τ2, the distance of the opening from the center of the shaft hole is R, and the number of the openings is Nr. , Where t is the thickness of each of the plurality of rotor cores,
τ1 ≧ 2πR / (4Nr)
t / 2 ≦ τ2 ≦ 2t
It is characterized by being set to.
[0018]
Furthermore, in the method for manufacturing an electric motor rotor according to claim 7, the secondary conductor forming openings each having a plurality of holes separated by a partitioning portion in each of the plurality of rotor cores are arranged at predetermined intervals in the circumferential direction. The angle formed by the center line of the partition part with respect to the line connecting the center of each rotor core and the center of the partition part is different between the rotor cores adjacent in the axial direction. The plurality of rotor cores are sequentially stacked, and the secondary conductor forming opening is filled with liquid aluminum and solidified to form a plurality of secondary conductors composed of a plurality of parts displaced in the axial direction. It was made to do.
[0019]
According to an eighth aspect of the present invention, as the plurality of rotor cores, a plurality of rotor cores having the same shape having a partition portion in which the angle gradually changes in the circumferential direction are prepared, and adjacent to each other in the axial direction. The rotor cores that are to be stacked are sequentially stacked while being shifted by at least one pitch of the opening for forming the secondary conductor.
[0020]
According to the ninth aspect of the present invention, after the rotor cores adjacent in the axial direction are shifted by at least one pitch , the center lines of the secondary conductors are rotated each time by shifting the rotor core by a predetermined distance in the circumferential direction. The center of the shaft hole formed in the center of the child core is inclined with respect to a line connecting in the axial direction .
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 shows a rotor core of an induction motor according to a first embodiment of the present invention, and particularly shows one of a plurality of rotor cores 1,..., 1 constituting the rotor core.
As shown in FIG. 1, each of a plurality of rotor cores 1,..., 1 stacked in the axial direction has a plurality of secondary conductor forming circular openings 2,. Are formed at predetermined intervals, and each secondary conductor forming opening 2 is composed of two adjacent semicircular holes 2a and 2b divided by a partition 1a of the core 1.
[0022]
Here, in the secondary conductor forming openings 2,..., 2 formed in each rotor core 1, the center of a rotating shaft (not shown) press-fitted into the shaft hole 6 and the center of the partition portion 1 a are formed. The angle θ formed by the center line of the partition portion 1a with respect to the connecting line is set so as to gradually change according to the position in the circumferential direction.
[0023]
When the secondary conductor is formed by aluminum die casting, a plurality of rotor cores 1 having the above-described shape are prepared, and adjacent rotor cores 1 are arranged in the circumferential conductors with secondary conductor forming openings 2,. Laminate by sequentially shifting the pitch or several pitches. Next, when the secondary conductor forming openings 2,..., 2 are filled with liquid aluminum and solidified, the aluminum secondary conductor 3 comprising two parts 3a and 3b separated from each other as shown in FIG. Are formed at predetermined intervals.
[0024]
When the rotor core 1 of FIG. 1 is used, 22 rod-shaped conductors 3,..., 3 are embedded as secondary conductors in the rotor core, and both ends in the axial direction are end rings (not shown). Are all short-circuited. After the rotor shaft (not shown) is press-fitted into the shaft hole 6, the rotor core is loosely inserted into a stator core (not shown) provided with a three-phase winding.
[0025]
FIG. 3 is a cross-sectional view of one of the aluminum secondary conductors 3,..., 3 cut at a predetermined interval perpendicular to the axis, and it can be seen that the angle of the partition portion 1a gradually changes.
[0026]
4 is a cross-sectional view of one of the aluminum secondary conductors 3,..., 3 cut along a plane including an axis.
[0027]
As shown in FIG. 4, when the magnetic flux φ passes through the parts 3a and 3b of the secondary conductor 3, circulating currents I ₁ and I ₂ flow inside the parts 3a and 3b, respectively. Since it does not flow beyond the slit, it becomes a local flow path. Therefore, the eddy current is greatly reduced, and the efficiency of the electric motor is improved.
[0028]
The present invention is characterized in that, in the above configuration, each secondary conductor 3 is separated into two parts 3a and 3b. In other words, two semicircular holes 2a and 2b are independently provided at adjacent positions as the openings 2 for forming each secondary conductor, and each of the two holes 2a and 2b is separated by A partition 1 a is formed on the rotor core 1. If the distance between the two holes 2a and 2b is large, the number of secondary conductors is simply increased. Therefore, the width of the partitioning portion 1a is narrowed, and each secondary conductor 3 2 is positioned at a position of substantially the same magnetic flux density level. Two parts 3a and 3b are arranged.
[0029]
As a result of the studies conducted so far by the inventors, the separation distance between the adjacent openings 2,..., 2 is τ1, the width of the partition portion 1a is τ2, and the center of the shaft hole 6 of the openings 2,. When the distance is R and the number of openings 2,..., 2 is Nr (see FIG. 5), the following results are obtained.
[0030]
(1) The openings 2,..., 2 may be of a unit functioning as a secondary conductor by aluminum die casting,
τ1 ≧ 2πR / (4Nr)
Is preferred.
(2) In order to reduce the number of magnetic fluxes passing through the partition 1a,
τ2 ≦ 2t (t: thickness of each rotor core 1)
Is preferred.
(3) The width of the partition part 1a is to ensure the strength during aluminum die casting.
τ2 ≧ t / 2
And more preferably
τ2 ≧ t
Should be.
[0031]
Next, the rotation angle of the partition part 1a will be considered.
Assuming that θ _TOTAL is the axial integral value (degree of twist or transition from the lowest to the highest in the axial direction) of the rotation angle of partition 1a, eddy current is reduced by making θ _TOTAL a multiple of 180 degrees. The larger the multiple, the smaller the amount of local flow. Moreover, when the shift of the rotation angle of the partition portion 1a when the rotor cores 1,..., 1 stacked in the axial direction are advanced is δθ,
δθ = (k × 180 / Nr) °
k: any integer,
If so, it can be realized by sequentially laminating a plurality of rotor cores manufactured by one mold. In this case, since only one mold is required, it is very advantageous in terms of equipment. However, if each of the secondary conductor forming openings 2 is individually processed, the dislocation is performed at an arbitrary pitch without any restriction. (With a twist).
[0032]
In addition, in the rotor core 1 shown in FIG. 1, the deviation of the rotation angle of the adjacent partition part 1a is
δθ = (1 × 180/22) ° = 8.18 °
(Dislocation (twist) angle: 180 °).
[0033]
Further, in the rotor core 1 shown in FIG. 6, k = 2 is set, and the deviation of the rotation angle of the adjacent secondary conductor partition 1a is
δθ = (2 × 180/22) ° = 16.36 °
(Dislocation angle: 360 °).
[0034]
Embodiment 2. FIG.
FIG. 7 shows the secondary conductor 3A of the induction motor according to the second embodiment of the present invention when the rotor is skewed.
[0035]
Skew means that the axis of rotation and the center line of the secondary conductor are not parallel, but are inclined at a certain angle. Specifically, each core constituting the rotor core is sequentially shifted in the circumferential direction. However, it is realized by stacking. This type of electric motor has an effect of suppressing torque pulsation during operation, but conversely has a drawback of a reduction in efficiency due to an increase in leakage current, and is used exclusively in small machines.
[0036]
When the secondary conductor is formed by aluminum die casting, a plurality of rotor cores 1 shown in FIG. 1 are prepared, and adjacent rotor cores 1 are sequentially shifted in the circumferential direction by one pitch or several pitches, and each rotation The child cores 1 are stacked while being shifted by a predetermined distance in the circumferential direction. Next, when the secondary conductor forming opening is filled with liquid aluminum and solidified, a plurality of aluminum secondary conductors 3A as shown in FIG. 7 are formed at predetermined intervals.
[0037]
FIG. 8 shows only two adjacent layers in the secondary conductor 3A shown in FIG. 7, so that two independent secondary conductors are not short-circuited (contacted). ), The skew angle and the size of the gap are set appropriately.
[0038]
In the first and second embodiments, each of the secondary conductors 3 and 3A is divided into two parts. However, the present invention is not limited to two parts and can be divided into two or more parts. However, in order to make the resistance of each of the parts divided into a plurality of parts substantially constant, the cross-sectional area in each cross section in the axial direction is made substantially constant.
[0039]
FIG. 9 shows a cross-shaped partition 1b formed on each rotor core 1 and each secondary conductor 3B divided into four parts. As the number of divisions increases in this way, eddy current reduction is more effective, but it is necessary to pay attention to the fact that the conductor cross-sectional area decreases because the volume of the partition portion 1b also increases.
[0040]
Furthermore, in the said embodiment, although the cross-sectional shape of each secondary conductor 3,3A, 3B was circular, shapes other than circular can also be employ | adopted.
[0041]
In FIG. 10, the cross-sectional shape of each secondary conductor 3C is not a circle but an ellipse. In this example, in order to set the cross-sectional area of the secondary conductor 3C cut along a plane perpendicular to the axis to be equal, the width of the partition portion 1c is increased as the length of the partition portion 1c is shortened. Thus, by elongating each secondary conductor 3C, the width of the magnetic path portion of the iron core can be increased, and the characteristics of the motor are improved.
[0042]
As a matter of course, it is also possible to adopt the “slack type” cross-sectional shape shown in FIG.
[0043]
Furthermore, in the said embodiment, although the example of the electric motor which functions as an induction machine in the whole operation area | region was shown, this invention is not limited to an induction motor, It is employable also to a synchronous motor.
[0044]
FIG. 11 shows one of a plurality of rotor cores 1,..., 1 stacked on an induction starting permanent magnet synchronous motor, and a plurality of circular secondary conductor forming openings on the circumference thereof. Portions 2, ..., 2 are formed at predetermined intervals. Each secondary conductor forming opening 2 is composed of two adjacent semicircular holes 2 a and 2 b divided by the partition 1 a of the core 1. Four permanent magnet insertion holes 7,..., 7 are formed in the periphery of the shaft hole 6 inside the secondary conductor forming openings 2,. One permanent magnet 4 is inserted into the.
[0045]
Since the process of forming the secondary conductor by aluminum die casting or the shape of the secondary conductor is the same as in the first or second embodiment, description thereof is omitted.
[0046]
In the above embodiment, when the plurality of rotor cores 1,..., 1 are stacked, the adjacent rotor cores 1 are sequentially shifted by at least one pitch in the circumferential direction. It may be shifted. That is, several identical rotor cores 1 (for example, three) are laminated, and then several pieces that are shifted by at least one pitch are similarly laminated. Thereafter, after a predetermined number of rotor cores are similarly laminated, a secondary conductor is formed by aluminum die casting.
[0047]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
According to the invention described in claim 1 among the present invention, each of the plurality of secondary conductor forming openings is constituted by a plurality of holes separated by the partition portion of the rotor core, and each of the secondary conductors Since each part is displaced in the axial direction, the circulating current flows only locally even if the magnetic flux passes through each part. Therefore, eddy currents generated in the plurality of secondary conductors are reduced, and the motor efficiency can be improved.
[0048]
According to the invention described in claim 2, since the axial cross-sectional areas of the plurality of parts are set to be substantially constant, the resistance of each part becomes substantially constant, and the eddy current can be reduced more effectively. .
[0049]
Furthermore, according to the invention described in claim 3, since the dislocation angle of each part is set to an integral multiple of 180 °, the eddy current generated in each part can be canceled efficiently.
[0050]
According to the invention described in claim 4, since a plurality of permanent magnets are embedded inside the secondary conductor, the present invention is applied not only to the induction motor but also to the synchronous motor for induction start. Can do.
[0051]
Further, according to the invention described in claim 5, since each of the secondary conductors is inclined with respect to the shaft hole, it is possible to suppress torque pulsation during motor operation and to improve reliability. Can do.
[0052]
According to the invention described in claim 6, the distance between adjacent openings is τ1, the width of the partition is τ2, the distance from the center of the shaft hole of the opening is R, the number of openings is Nr, a plurality Where t is the thickness of each of the rotor cores
τ1 ≧ 2πR / (4Nr)
t / 2 ≦ τ2 ≦ 2t
Therefore, it is possible to form a predetermined number of secondary conductors without unnecessarily increasing the number of secondary conductors, reduce the number of magnetic fluxes passing through the partition, and ensure strength during aluminum die casting. be able to.
[0053]
Furthermore, according to the invention described in claim 7, a plurality of openings having a plurality of holes separated by the partitioning portions are formed in each rotor core, and the inclination angles of the partitioning portions of the adjacent rotor cores are different. In this way, the rotor cores are sequentially laminated, and the secondary conductor composed of a plurality of parts displaced in the axial direction is formed by filling and solidifying the liquid aluminum in the openings. Even if the magnetic flux passes, the circulating current flows only locally, eddy currents generated in the secondary conductor are reduced, and the motor efficiency can be improved.
[0054]
Further, according to the invention described in claim 8, a plurality of identically shaped rotor cores having partition portions whose inclination angles gradually change in the circumferential direction are prepared, and adjacent rotor cores are formed as secondary conductors. Since the openings are sequentially shifted by at least one pitch, only one mold is required, and the rotor can be manufactured at low cost.
[0055]
According to the invention of claim 9, since each of the secondary conductors is inclined with respect to the shaft hole by shifting the adjacent rotor cores by at least one pitch and further shifting by a predetermined distance, Torque pulsation during operation of the electric motor can be suppressed, and reliability can be improved.
[Brief description of the drawings]
FIG. 1 is a plan view of a rotor core of an electric motor according to a first embodiment of the present invention.
FIG. 2 is a perspective view of a secondary conductor formed on the rotor core of FIG.
3 is a cross-sectional view of the secondary conductor of FIG. 2 cut at a predetermined interval perpendicular to the axis, and (a) to (l) show how the inclination angle of the partitioning portion gradually changes, respectively. Yes.
4 is a partial cross-sectional view of the secondary conductor of FIG. 2 cut along a plane including an axis.
5 is a partially enlarged plan view for explaining the size, the separation distance, and the like of a plurality of openings formed in the rotor core of FIG. 1; FIG.
FIG. 6 is a plan view of a modification of the rotor core of FIG. 1;
FIG. 7 is a perspective view of a secondary conductor formed in the rotor of the induction motor according to the second embodiment of the present invention.
8 is a perspective view showing only two adjacent layers in the secondary conductor of FIG. 7. FIG.
FIG. 9 is a cross-sectional view perpendicular to the axis of a modified example of the secondary conductor.
FIGS. 10A and 10B are cross-sectional views perpendicular to the axis of another modified example of the secondary conductor, and FIGS. 10A and 10B respectively show portions separated in the axial direction. FIGS.
FIG. 11 is a plan view of another modification of the rotor core of FIG. 1;
FIG. 12 is a plan view of a rotor core of a conventional electric motor.
13 is a partial cross-sectional view of a secondary conductor formed in the rotor core of FIG. 12 cut along a plane including an axis.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rotor core, 1a Partition part, 2 Opening part for secondary conductor formation,
2a, 2b secondary conductor formation hole, 3, 3A, 3B, 3C secondary conductor,
3a, 3b Secondary conductor parts, 4 permanent magnets, 6 shaft holes,
7 Permanent magnet insertion hole

Claims (9)

An electric motor comprising: a plurality of rotor cores stacked in the axial direction and having a plurality of openings for forming a secondary conductor; and a secondary conductor formed by filling the opening for forming a secondary conductor with aluminum. A rotor,
The plurality of openings of each rotor core are formed at predetermined intervals in the circumferential direction, and each of the plurality of openings is constituted by a plurality of holes separated by a partition provided in the rotor core, Each of the secondary conductors is composed of a plurality of parts separated by the partition, and the center line of the partition forms a line connecting the center of each rotor core and the center of the partition. A rotor for an electric motor, wherein the rotor cores adjacent to each other in the axial direction have different angles, and the plurality of parts of each of the secondary conductors are displaced in the axial direction of the secondary conductor.   The electric motor rotor according to claim 1, wherein an axial sectional area of the plurality of parts is set to be substantially constant.   The electric motor rotor according to claim 1 or 2, wherein the dislocation angle of each of the parts is set to an integral multiple of 180 °.   The rotor for an electric motor according to any one of claims 1 to 3, wherein a plurality of permanent magnets are embedded inside the secondary conductor. 5. The center line according to claim 1 , wherein the center line of each of the secondary conductors is inclined with respect to a line connecting the centers of shaft holes formed at the centers of the rotor cores in the axial direction . Electric motor rotor. The separation distance between adjacent openings is τ1, the width of the partition is τ2, the distance from the center of the shaft hole of the opening is R, the number of openings is Nr, and the thickness of each of the plurality of rotor cores T
τ1 ≧ 2πR / (4Nr)
t / 2 ≦ τ2 ≦ 2t
The rotor for an electric motor according to any one of claims 1 to 5, wherein the rotor is set. A plurality of openings for forming a secondary conductor having a plurality of holes separated by a partition portion in each of a plurality of rotor cores are formed at predetermined intervals in the circumferential direction, and the center of each rotor core and the partition portion The plurality of rotor cores are sequentially laminated so that the angle formed by the center line of the partition portion with respect to the line connecting the centers of the two is different between the axially adjacent rotor cores to form the secondary conductor A method of manufacturing an electric motor rotor in which a plurality of secondary conductors composed of a plurality of parts displaced in the axial direction are formed by filling liquid aluminum in a working opening and solidifying. As the plurality of rotor cores, a plurality of rotor cores having the same shape having partition portions in which the angle gradually changes in the circumferential direction is prepared, and the rotor core adjacent in the axial direction is formed as a secondary conductor forming opening. The method of manufacturing an electric motor rotor according to claim 7, wherein at least one pitch of the parts is sequentially shifted and stacked. The rotor cores adjacent to each other in the axial direction are shifted by at least one pitch, and further , the center lines of the secondary conductors are shifted by a predetermined distance in the circumferential direction so that the center holes of the shaft holes formed at the centers of the respective rotor cores. The method for manufacturing an electric motor rotor according to claim 8, wherein the center is inclined with respect to a line connected in the axial direction .

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