JP2016135055A - Rotor core for reluctance motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotor core which prevents deformation with respect to a rotational centrifugal force load while maintaining reluctance torque.SOLUTION: A rotor core 1 is rotated while utilizing reluctance torque by including a plurality of magnetic flux barrier slits 2, 3 and 4 which are provided in a radial direction to be protrusive for a rotation center axis α for each pole. Among the plurality of magnetic flux barrier slits 2, 3 and 4, the magnetic flux barrier slits 3 and 4 include a plurality of bridges 3c, 3d, 4c and 4d for suppressing radial expansion caused by a centrifugal force. When a linear direction passing a center G of gravity in an area within one pole closer to an outer circumference than the magnetic flux barrier slit 4 at an innermost circumferential side among the plurality of magnetic flux barrier slits 2, 3 and 4 and orthogonal to the rotation center axis α is defined as a center-of-gravity direction, the plurality of bridges 3c, 3d, 4c and 4d are spread over the magnetic flux barrier slits 3 and 4 in the center-of-gravity direction and the deformation with respect to the rotational centrifugal force load is prevented while maintaining the reluctance torque.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a rotor core that rotates using reluctance torque.

  Conventionally, as a rotor core for a reluctance motor, there are a plurality of magnetic flux barrier slits provided in a radial direction so as to be convex on the rotation center axis per pole, so that a magnetic flux easily flows and a magnetic flux hardly flows. The structure which rotates using the reluctance torque formed in the middle is known (for example, refer patent document 1, 2).

However, in recent years, the demand for high-speed rotation of the rotor core due to the demand for high-speed reluctance motors has been increasing, and the configuration with only the conventional magnetic flux barrier slits is a deformation to the rotational centrifugal force load during high-speed rotation of the rotor core. It has become difficult to respond.
Therefore, a configuration in which the mechanical strength is increased to cope with the deformation of the rotor core with respect to the rotational centrifugal load during high-speed rotation is known (for example, see Patent Documents 3 and 4).
In these configurations, by providing a bridge straddling the magnetic flux barrier slit, the mechanical strength against the rotational centrifugal force load is increased and the deformation of the rotor core is suppressed.

However, in the configuration of the bridge arrangement of Patent Document 3, the number of bridges arranged in each magnetic flux barrier slit is only one, the mechanical strength is not sufficient, and the bridge arrangement is also long. In this arrangement, not only the tensile stress generated in the vertical direction but also the bending stress generated in the width direction of the bridge can be generated. For this reason, it is necessary to resist bending stress, and it is difficult to reduce the width of the bridge.
A wide bridge width is not preferable because it reduces the salient pole ratio of the rotor core and causes a decrease in reluctance torque.

  In addition, in the arrangement configuration of the bridge in Patent Document 4, only the innermost magnetic flux barrier slit has a plurality of bridges and the mechanical strength is ensured, but the innermost magnetic flux is disclosed. Increasing the strength of the barrier slit is not sufficient, and no detailed description of the arrangement of the plurality of bridges in the magnetic flux barrier slit is given.

JP 2013-172559 A JP 2002-10594 A JP 2001-258222 A JP-A-10-257700

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a rotor core that prevents deformation due to a rotating centrifugal force load while maintaining reluctance torque.

According to the first invention of the present application, the rotor core has a plurality of magnetic flux barrier slits provided in the radial direction so as to be convex on the rotation center axis per pole, so that the magnetic flux easily flows and the magnetic flux hardly flows. Rotate using the reluctance torque formed between the two.
Then, both end portions of the plurality of magnetic flux barrier slits are closed by an outer peripheral bridge that forms an outer peripheral edge.
In addition, at least one of the plurality of magnetic flux barrier slits has a plurality of bridges that suppress expansion in the radial direction due to centrifugal force.
Then, among the plurality of magnetic flux barrier slits, a linear direction that passes through the center of gravity of the region within one pole on the outer peripheral side from the innermost magnetic flux barrier slit including the innermost magnetic flux barrier slit is orthogonal to the rotation center axis. Assuming the direction of the center of gravity, the plurality of bridges straddle the magnetic flux barrier slit in the direction of the center of gravity.

Thereby, it has a some bridge | bridging in a magnetic flux barrier slit, and can suppress the expansion | swelling of the radial direction by centrifugal force.
Further, since the plurality of bridges straddle the magnetic flux barrier slit in the center of gravity direction, each of the plurality of bridges is configured to generate only tensile stress generated in the length direction of the bridge. Even when it is deformed, the bending stress generated in the width direction of the bridge can be suppressed. For this reason, the width | variety of each bridge | bridging can be narrowed, the reduction | decrease of a salient pole ratio can be suppressed, and a reluctance torque can be maintained.
As a result, it is possible to provide a rotor core that prevents deformation due to rotational centrifugal force load while maintaining reluctance torque.

According to the second invention of the present application, the width of the outer peripheral bridge of the magnetic flux barrier slit provided with the plurality of bridges is smaller than the width of the outer peripheral bridge of the magnetic flux barrier slit provided with the plurality of bridges.
As a result, the slit area of the magnetic flux barrier slit provided with a plurality of bridges can be increased by the area of the plurality of bridges, so that the reduction of the salient pole ratio can be further suppressed and the reluctance torque is further maintained. be able to.

According to the third invention of the present application, there are a plurality of magnetic flux barrier slits provided with a plurality of bridges, and the bridges provided in different magnetic flux barrier slits are arranged on a straight line in the center of gravity direction.
Thereby, since the bridge | bridging provided in the different magnetic flux barrier slit exists on a straight line, mechanical strength can be raised more and the deformation | transformation with respect to a rotational centrifugal force load can be suppressed more.

It is explanatory drawing of a rotor core (1st Example). It is a comparison figure with the prior art example of generated stress (1st Example). (A) It is explanatory drawing of a rotor core, (b) It is a comparison figure with 1st Example of generated stress (2nd Example). It is explanatory drawing of the gravity center direction in the case of low symmetry (modified example). It is an example of the number of other bridges in the magnetic flux barrier slit on the innermost circumference side (modified example). It is an example of the other shape of a magnetic-flux barrier slit (modification).

  Hereinafter, modes for carrying out the invention will be described based on examples.

[Example 1]
A rotor core 1 according to a first embodiment of the present invention is shown in FIG. FIG. 1 shows only one pole portion of the rotor core 1. Hereinafter, unless otherwise specified, the rotor core 1 will be described by showing only one pole portion.
The rotor core 1 is obtained by laminating a plurality of disk-shaped core sheets having the same shape made of a high permeability material made of an electromagnetic steel plate or the like in the direction of the rotation center axis α.
The rotor core 1 has a plurality of magnetic flux barrier slits 2 to 4 provided in a radial direction so as to protrude on the rotation center axis α per pole, so that the magnetic flux flows between the direction in which the magnetic flux easily flows and the direction in which the magnetic flux does not easily flow. Rotates using the reluctance torque formed in

Here, the plurality of barrier slits 2 to 4 have an arc shape centered on an axis β different from the rotation center axis α, and are arranged in the order of the barrier slits 2, 3, 4 from the outer peripheral side.
Then, both end portions of the plurality of magnetic flux barrier slits 2 to 4 are closed by outer peripheral bridges 2a, 2b, 3a, 3b, 4a, and 4b that form outer peripheral edges.

Moreover, two magnetic flux barrier slits 3 and 4 on the inner peripheral side among the plurality of magnetic flux barrier slits 2 to 4 have a plurality of bridges 3c, 3d and 4c and 4d that suppress expansion in the radial direction due to centrifugal force. Yes.
Then, among the plurality of magnetic flux barrier slits, including the magnetic flux barrier slit 4 on the innermost peripheral side and passing through the center of gravity G of the region within one pole on the outer peripheral side from the magnetic flux barrier slit 4 on the innermost peripheral side, orthogonal to the rotation center axis α Assuming that the straight line direction is the center of gravity direction, the plurality of bridges 3c, 3d and 4c, 4d straddle the magnetic flux barrier slits 3 and 4 in the center of gravity direction, respectively.

  Also, the width of the outer peripheral bridges 3a, 3b and 4a, 4b of the magnetic flux barrier slits 3 and 4 provided with the plurality of bridges 3c, 3d and 4c, 4d is equal to the outer periphery of the magnetic flux barrier slit 2 provided with no plural bridges. It is smaller than the width of the bridges 2a and 2b.

  Further, in the magnetic flux barrier slits 3 and 4 provided with the plurality of bridges 3c, 3d and 4c and 4d, the bridges 3c, 4c and 3d and 4d provided in the different magnetic flux barrier slits 3 and 4 exist on a straight line in the center of gravity direction. Is arranged.

Furthermore, the plurality of magnetic flux barrier slits 2 to 4 may be hollow or may be embedded with a magnetic material such as a permanent magnet.
In addition, when the magnetic body is embedded in the magnetic flux slits 2-4, even if the magnetic body is embedded in all the magnetic flux barrier slits 2-4, at least one magnetic flux barrier slit of the plurality of magnetic flux barrier slits 2-4. The magnetic body may be embedded in 2-4.

[Effect of Example 1]
The rotor core 1 according to the first embodiment has a plurality of magnetic flux barrier slits 2 to 4 provided in a radial direction so as to be convex to the rotation center axis α per pole, so that the magnetic flux easily flows and the magnetic flux does not easily flow. It rotates using the reluctance torque formed between the directions.
Then, both end portions of the plurality of magnetic flux barrier slits 2 to 4 are closed by outer peripheral bridges 2a, 2b, 3a, 3b, 4a, and 4b that form outer peripheral edges.

Moreover, two magnetic flux barrier slits 3 and 4 on the inner peripheral side among the plurality of magnetic flux barrier slits 2 to 4 have a plurality of bridges 3c, 3d and 4c and 4d that suppress expansion in the radial direction due to centrifugal force. Yes.
Then, among the plurality of magnetic flux barrier slits 2 to 4, the central axis of rotation passes through the center of gravity G of the region within one pole on the outer peripheral side from the innermost magnetic flux barrier slit 4 including the innermost magnetic flux barrier slit 4. Assuming that the linear direction orthogonal to α is the center of gravity direction, the plurality of bridges 3c, 3d and 4c, 4d straddle the magnetic flux barrier slits 3 and 4 in the center of gravity direction, respectively.

As a result, a plurality of bridges 3c, 3d and 4c, 4d are provided in the magnetic flux barrier slits 3 and 4, and radial expansion due to centrifugal force can be suppressed.
Further, since the plurality of bridges 3c, 3d and 4c, 4d straddle the magnetic flux barrier slits 3 and 4 in the center of gravity direction, the plurality of bridges 3c, 3d and 4c, 4d are respectively connected to the bridges 3c, 3d, 4c, Only the tensile stress generated in the length direction of 4d is generated, and even when the magnetic flux barrier slits 3 and 4 are deformed, the bending stress generated in the width direction of the bridges 3c, 3d, 4c and 4d is generated. Since it can be suppressed, the width of each of the bridges 3c, 3d, 4c, and 4d can be narrowed, the decrease in the salient pole ratio can be suppressed, and the reluctance torque can be maintained.
For this reason, the rotor core 1 which prevents the deformation | transformation with respect to a rotational centrifugal force load can be provided, maintaining a reluctance torque.

In the rotor core 1 according to the first embodiment, the width of the outer peripheral bridges 3a, 3b, 4a, and 4b of the magnetic flux barrier slits 3 and 4 provided with the plurality of bridges 3c, 3d and 4c and 4d is not provided with the plurality of bridges. The width of the outer peripheral bridges 2a and 2b of the magnetic flux barrier slit 2 is smaller.
As a result, the slit area of the magnetic flux barrier slits 3 and 4 provided with the plurality of bridges 3c, 3d and 4c and 4d can be enlarged by the area of the plurality of bridges 3c, 3d and 4c and 4d. The decrease in the ratio can be further suppressed, and the reluctance torque can be further maintained.

In the rotor core 1 according to the first embodiment, the magnetic flux barrier slits 3 and 4 provided with a plurality of bridges 3c, 3d and 4c and 4d have bridges 3c, 4c and 3d and 4d provided at different magnetic flux barrier slits 3 and 4 at the center of gravity. It is arranged so that it exists on a straight line in the direction.
As a result, the bridges 3c, 4c and 3d, 4d provided in the different magnetic flux barrier slits 3 and 4 are in a straight line, so that the mechanical strength can be further increased and the deformation against the rotational centrifugal force load can be further suppressed. Can do.

Moreover, in the rotor core 1 of Example 1, a magnetic body can be embedded in any of the plurality of magnetic flux barrier slits 2 to 4.
For this reason, when the magnetic body is embedded, the rotor core 1 can rotate using not only the reluctance torque but also the magnetic torque.
In this case, the center of gravity G is the position of the center of gravity including the embedded magnetic body.

The plurality of barrier slits 2 to 4 have an arc shape.
For this reason, when the magnetic material is embedded, the surface area of the magnetic material can be increased, and the magnetic torque when the magnetic material is embedded can be increased.

Here, FIG. 2 shows a relative comparison of the magnitudes of bending stresses generated at positions I, II and III by simulation.
2A is the rotor core 1 of the first embodiment, FIG. 2B is the conventional rotor core, and FIG. 2C is the occurrence of the rotor core 1 of the first embodiment and the conventional rotor core at corresponding positions. The relative comparison figure of the magnitude of the bending stress to do is shown.
Further, the position of I corresponds to the position of the outer peripheral bridges 4a, II in FIG. 1 and the position of the bridge 3d, III in FIG. 1 corresponds to the bridge 4d in FIG. The example outer bridge and the bridge width are equal.

From FIG. 2C, the magnitude of the stress generated at the position I is 20% smaller in the first embodiment than in the conventional example, and the magnitude of the stress generated at the position II is the first embodiment. This is 9% smaller than the conventional example.
The magnitude of the stress generated at the position III is 5.5% smaller in the first embodiment than in the conventional example, and in the first embodiment, the first embodiment is at any position of I, II, and III. The magnitude of the stress generated from the conventional example is smaller.

[Example 2]
A rotor core 1 according to a second embodiment of the present invention is shown in FIG. The same functional components as those in the first embodiment are denoted by the same reference numerals.
In the rotor core 1 of the second embodiment, a plurality of bridges 4c and 4d are provided on the innermost magnetic flux barrier slit 4, and each of the plurality of bridges 4c and 4d of the innermost magnetic flux barrier slit 4 is Each of the bridges 4c and 4d supports the bridges 4c and 4d so as to straddle the magnetic flux barrier slit 4 in the direction of the center of gravity g of each region within one pole on the outer peripheral side.

Here, based on the analysis result of the simulation, the inventors, in the magnetic flux barrier slit 4 on the innermost peripheral side, the plurality of bridges 4c and 4d straddle the magnetic flux barrier slit 4 in the direction of the center of gravity g of each region from the direction of the center of gravity. It has been found that the bending stress generated in each of the bridges 4c and 4d is suppressed (see FIG. 3B).
Here, based on the result of detailed analysis by the inventors, the direction of the center of gravity g of each region within one pole on the outer peripheral side of each bridge 4c and 4d supported by each bridge 4c and 4d is the bridge 4c and This magnetic flux including the magnetic flux barrier slit 3 adjacent to the innermost magnetic flux barrier slit 4 is partitioned by a line segment in the center of gravity direction (hereinafter also referred to as a partition line segment) that is equidistant from the bridge 4d. The direction of the center of gravity of each region in one pole of the rotor core 1 on the outer peripheral side from the barrier slit 3 is set.
That is, the bridges 4c and 4d support the respective regions via the portion between the magnetic flux barrier slit 3 and the magnetic flux barrier slit 4.
Each area is indicated by hatching in the drawing.
The direction of the center of gravity g of each region is the direction of the center of gravity g of each region including the embedded magnetic body when the magnetic body is embedded in any of the magnetic flux barrier slits 2 to 4. Yes.

  Therefore, since the bending stress generated in the plurality of bridges 4c and 4d of the innermost magnetic flux barrier slit 4 can be suppressed by the configuration of the second embodiment, the plurality of bridges 4c of the innermost magnetic flux barrier slit 4 and The width of 4d can be narrowed, the reduction of the salient pole ratio can be further suppressed, and the reluctance torque can be further maintained.

[Modification]
Various modifications can be considered for the present invention without departing from the gist thereof.
In Example 1, the magnetic flux barrier slits 2 to 4 had a highly symmetric arrangement and a highly symmetric shape, but the magnetic flux barrier slits 2 to 4 were arranged asymmetrically as shown in FIG. Or it is good also as an asymmetrical shape.

For example, when the magnetic flux barrier slits 2 to 4 are arranged asymmetrically as shown in FIG. 4A, the direction of the center of gravity is the direction shown in the figure, and as shown in FIG. When the shape is asymmetric, the direction of the center of gravity is the direction shown in the figure.
Here, in Fig.4 (a), the magnetic flux barrier slits 2-4 are hollow, and in FIG.4 (b), the magnetic body is embedded in the magnetic flux barrier slits 2-4.
FIG. 4B shows a case where the specific gravity of the magnetic material to be embedded is larger than the specific gravity of the rotor core 1.
In FIG. 4B, when the specific gravity of the magnetic material is smaller than the specific gravity of the rotor core 1, the position of the center of gravity G changes, so that the direction of the center of gravity is naturally different.

In the second embodiment, the number of bridges provided in the innermost magnetic flux barrier slit 4 is two, but the number of bridges provided may be greater than two. For example, in FIG. 5, the number of bridges provided in the magnetic flux barrier slit 4 is 3 (see FIG. 5A), 4 (see FIG. 5B), and 5 (see FIG. 5C). Shows the case.
The dividing line segments in the respective cases of the number of bridges and the respective regions supported by the respective bridges are as illustrated.
Each area is indicated by hatching in the drawing.
Here, each segment line segment is a line segment in the center of gravity direction that is equidistant from adjacent bridges.

In the first and second embodiments, the magnetic flux barrier slits 2 to 4 have an arc shape, but the magnetic flux barrier slits 2 to 4 only have to be provided in the radial direction so as to be convex to the rotation center axis α. The magnetic flux barrier slits 2 to 4 may include a portion having a linear shape.
For example, as shown to Fig.6 (a), it may be comprised only from the part which exhibits a linear shape, and as shown to FIG.6 (b), as a structure which combined the part which exhibits a linear shape and circular arc shape. Also good.
In addition, about the part which exhibits a linear shape, it becomes easy to ensure processing accuracy.

In the first and second embodiments, the rotor core 1 is provided with three magnetic flux barrier slits 2 to 4 in the radial direction per pole. However, the number of magnetic flux barrier slits provided is limited to this number. Any number of magnetic flux barrier slits may be provided per pole as long as there are a plurality of them.
In the first and second embodiments, the configuration of the so-called four-pole rotor core 1 is shown. However, the number of poles of the rotor core 1 is not limited to this number, and the number of poles of the rotor core 1 is set to six, eight, etc. Also good.

1 Rotor core 2, 3, 4 Magnetic flux barrier slit 2a, 2b
2a, 2b, 3a, 3b, 4a, 4b outer bridge
3c, 3d, 4c, 4d Bridge α Rotation center axis G Center of gravity

Claims (6)

By having a plurality of magnetic flux barrier slits (2, 3, 4) provided in a radial direction so as to be convex to the rotation center axis (α) per pole, a direction in which the magnetic flux easily flows and a direction in which the magnetic flux does not easily flow are provided. In the rotor core (1) that rotates using the reluctance torque formed between
Both end portions of the plurality of magnetic flux barrier slits (2, 3, 4) are closed by outer peripheral bridges (2a, 2b, 3a, 3b, 4a, 4b) forming outer peripheral edges,
Among the plurality of magnetic flux barrier slits (2, 3, 4), at least one magnetic flux barrier slit (3, 4) has a plurality of bridges (3c, 3d, 4c, 4d) for suppressing radial expansion due to centrifugal force. Have
Among the plurality of magnetic flux barrier slits (2, 3, 4), the innermost magnetic flux barrier slit (4) is included, and the innermost magnetic flux barrier slit (4) is disposed within the one pole on the outer peripheral side. When the linear direction passing through the center of gravity (G) of the region and orthogonal to the rotation center axis (α) is the center of gravity direction,
The rotor core (1), wherein the plurality of bridges (3c, 3d, 4c, 4d) straddle the magnetic flux barrier slits (3, 4) in the center of gravity direction. Rotor core (1) according to claim 1,
The width of the outer peripheral bridges (3a, 3b, 4a, 4b) of the magnetic flux barrier slits (3, 4) provided with the plurality of bridges (3c, 3d, 4c, 4d) is set such that the plurality of bridges (3c, 3d, The rotor core (1) is smaller than the width of the outer peripheral bridge (2a, 2b) of the magnetic flux barrier slit (2) not provided with 4c, 4d). In the rotor core (1) according to claim 1 or 2,
There are a plurality of magnetic flux barrier slits (3, 4) provided with the plurality of bridges (3c, 3d, 4c, 4d), and bridges (3c, 4c, 3d, 4d) provided in different magnetic flux barrier slits (3, 4). The rotor core (1) is arranged so as to be on a straight line in the direction of the center of gravity. In the rotor core (1) according to any one of claims 1 to 3,
The plurality of bridges (4c, 4d) are provided in the innermost magnetic flux barrier slit (4),
Each of the plurality of bridges (4c, 4d) of the magnetic flux barrier slit (4) on the innermost peripheral side is the one on the outer peripheral side than the respective bridges (4c, 4d) supported by the respective bridges (4c, 4d). A rotor core (1) characterized by straddling the magnetic flux barrier slit (4) in the direction of the center of gravity (g) of each region in the pole. In the rotor core (1) according to any one of claims 1 to 4,
A rotor core (1), wherein a magnetic material is embedded in any of the plurality of magnetic flux barrier slits (2, 3, 4). In the rotor core (1) according to any one of claims 1 to 5,
The rotor core (1), wherein the plurality of magnetic flux barrier slits (2, 3, 4) have a circular arc portion.

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