Embedded magnet type rotor

Abstract

To increase the number of revolutions of a rotor while suppressing loss.SOLUTION: The rotor 20 includes the rotor core 21 having the plurality of magnet insertion holes 22 that are formed at predetermined intervals in the circumferential direction and into which the magnets Z are inserted, and the cavity portions 24 that communicate with one end of each of the plurality of magnet insertion holes 22, the yokes 242 that are provided inside the plurality of cavity portions 24 so as to be movable in the radial direction of the rotor core 21, and the elastic members 243 that are provided inside the plurality of cavity portions 24 and press the yokes 242 in the radial direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an interior permanent magnet rotor. [Background technology]

[0002] The rotor of the interior permanent magnet synchronous motor of Patent Document 1 has holes that prevent short-circuiting of magnetic flux from the circumferential ends of the holes in which the magnets are embedded to the bridges on the outer periphery, preventing magnetic short-circuiting of the rotor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-87074 Summary of the Invention [Problem to be solved by the invention]

[0004] The narrower the radial width of the bridge in the rotor, the less magnetic flux from the magnets leaks into the rotor, allowing more magnetic flux to interlink with the coil. However, induced voltage occurs in the coil, making it difficult to pass current. One solution to this problem is to use field-weakening control, but if field-weakening control is used to increase the rotor rotation speed, the amount of current that does not affect rotor rotation increases, resulting in greater loss (copper loss).

[0005] The present invention has been made in consideration of these points, and has an object to increase the rotation speed of the rotor while suppressing losses. [Means for solving the problem]

[0006] An embedded magnet rotor according to one aspect of the present invention comprises a rotor core having a plurality of magnet insertion holes formed at predetermined intervals in the circumferential direction and into which magnets are inserted, and a void portion communicating with one end of each of the plurality of magnet insertion holes; a yoke disposed inside each of the plurality of void portions so as to be movable radially of the rotor core; and an elastic member disposed inside each of the plurality of void portions and pressing the yoke radially.

[0007] The yoke may have a first yoke portion located closer to the magnet insertion hole portion in the circumferential direction, and a second yoke portion located farther from the magnet insertion hole portion in the circumferential direction and longer than the first yoke portion in the radial direction, and the elastic member may be provided between the end face of the gap portion and the first yoke portion along the radial direction.

[0008] The gap portion has a first gap portion located on the side closer to the magnet insertion hole portion in the circumferential direction, where the first yoke portion is movable in the radial direction and the elastic member is expandable and contractable, and a second gap portion located on the side farther from the magnet insertion hole portion in the circumferential direction, where the second yoke portion is movable in the radial direction, and the first yoke portion and the second yoke portion pressed by the elastic member may be in contact with the radially inner end face of the gap portion.

[0009] The second yoke portion may approach the radially outer end surface of the second gap portion when the elastic member contracts.

[0010] The second yoke portion may be located at a position where it does not come into contact with the radial end surface of the second gap portion when the elastic member is fully compressed.

[0011] The cross-sectional area of ​​the second yoke portion when cut along a plane perpendicular to the radial direction may decrease as it approaches the radially outer end face of the second gap portion.

[0012] When the rotation speed of the rotor core exceeds a base rotation speed, the elastic member may be pushed by centrifugal force acting on the yoke and contract more as the rotation speed increases.

[0013] The magnet may further include a support portion made of a non-magnetic material that is provided between the magnet and the elastic member inside each of the plurality of gap portions and prevents the elastic member from moving toward the magnet. [Effects of the Invention]

[0014] According to the present invention, it is possible to suppress losses while increasing the rotation speed of the rotor. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a diagram showing an overview of a motor 1 according to an embodiment of the present invention. [Figure 2] 3A and 3B are diagrams showing the configuration of a gap portion 24. FIG. [Figure 3] 10 is a diagram showing the configuration of the gap 24 when the elastic member 243 is in the most contracted state. FIG. [Figure 4] FIG. 10 is a view showing a second yoke portion 242b that does not contact the end surface S3. [Figure 5] FIG. 10 is a diagram showing a second yoke portion 242b having a small area in contact with the end surface S3. DETAILED DESCRIPTION OF THE INVENTION

[0016] <Motor 1 Overview> Fig. 1 is a diagram showing an overview of a motor 1 according to this embodiment. Fig. 1 shows a cross-sectional view cut along a plane perpendicular to the axial direction of the rotating shaft of the motor 1. The motor 1 is an embedded magnet synchronous motor, and includes a rotating shaft 10, a stator 11, coils 12, and a rotor 20.

[0017] The stator 11 is located on the outer diameter side of the rotor 20 and is a cylindrical stator formed by laminating annular soft magnetic material in the axial direction. A plurality of teeth are formed on the inner circumference of the stator 11, and a coil 12 is wound around each of the plurality of teeth. In FIG. 1, as an example, a coil 12 is wound around each of 12 teeth. By winding the coils 12 around the inner circumference of the stator 11 in this way, a magnetic field is generated inside the stator 11.

[0018] The rotor 20 is a rotor located on the outer diameter side of the rotating shaft 10 and on the inner diameter side of the stator 11, and is an embedded magnet rotor with multiple magnets Z embedded in it. The rotor 20 has a rotor core 21, and the rotor core 21 has multiple magnet insertion holes 22, multiple flux barriers 23, and multiple gaps 24. In FIG. 1 , only one of the multiple magnet insertion holes 22, one of the multiple flux barriers 23, one of the multiple gaps 24, and one of the multiple magnets Z are labeled with a reference symbol.

[0019] The rotor core 21 is formed into a cylindrical shape by laminating annular magnetic material in the axial direction, and is provided to be rotatable in the rotation direction (circumferential direction) of the rotating shaft 10. A plurality of magnet insertion holes 22 are formed at predetermined intervals in the circumferential direction, and magnets Z are inserted into them. Each magnet insertion hole 22 is filled with a magnet Z of the same shape and size as the magnet insertion hole 22. The magnet insertion holes 22 are formed so as to extend in the axial direction as a rectangle that is long in the circumferential direction of the rotor 20, and one of the two end portions is closer to the center of the motor 1 than the other end portion.

[0020] The flux barrier 23 is formed to extend radially inward from one of both ends of the magnet insertion hole 22 that is closest to the center of the motor 1. The closer the flux barrier 23 is to the center of the motor 1, the larger the cross-sectional area of ​​the flux barrier 23 when cut along a plane perpendicular to the radial direction. The flux barrier 23 is formed to penetrate the rotor 20 in the axial direction, and the inside of the flux barrier 23 is, for example, an air gap.

[0021] The voids 24 are formed to extend radially inward and outward from one of the ends of the magnet insertion hole 22 that is farthest from the center of the motor 1. The area of ​​the radially inner end face of the void 24 is larger than the area of ​​the radially outer end face of the void. Each of the multiple voids 24 communicates with one end of each of the multiple magnet insertion holes 22, and each of the multiple flux barriers 23 communicates with the other end of each of the multiple magnet insertion holes 22. The voids 24 are formed to penetrate the rotor 20 in the axial direction. The internal structure of the cavity 24 will be described in detail below.

[0022] <Configuration of the gap 24> Fig. 2 is a diagram showing the configuration of the gap portion 24. Fig. 2 is an enlarged view of portion E of the motor 1 shown in Fig. 1. Fig. 2 shows magnetic flux M1 and magnetic flux M2 generated radially outward from the magnet Z. Magnetic flux M1 is magnetic flux that passes through the surface of the rotor 20 and interlinks with the coil 12, while magnetic flux M2 is magnetic flux that passes near the outer peripheral surface of the rotor 20 and advances radially inward from the magnet Z (so-called "leakage magnetic flux").

[0023] The gap 24 has a first gap portion 24a, a second gap portion 24b, and a third gap portion 24c. In the gap 24, the third gap portion 24c, the first gap portion 24a, and the second gap portion 24b are connected in this order from the side closer to the magnet insertion hole 22 in the circumferential direction.

[0024] The first gap portion 24a is a rectangular gap portion whose longitudinal direction is along the radial direction of the rotor 20, and is located closer to the magnet insertion hole 22 than the second gap portion 24b in the circumferential direction.

[0025] The second gap portion 24b is a rectangular gap portion whose longitudinal direction is along the radial direction of the rotor 20 and is in parallel communication with the first gap portion 24a. The inner circumferential surface of the second gap portion 24b on the radially central side is located at the same position as the inner circumferential surface of the first gap portion 24a on the central side. On the other hand, the inner circumferential surface of the second gap portion 24b on the radially outer side is located outward from the inner circumferential surface of the first gap portion 24a on the outer side. Therefore, the second gap portion 24b is longer in the radial direction than the first gap portion 24a.

[0026] The third gap portion 24c is located between the magnet insertion hole 22 and the first gap portion 24a in the circumferential direction, and is curved so as to connect the magnet insertion hole 22 and the first gap portion 24a. Here, the third gap portion 24c has a fan shape.

[0027] A support portion 241, a yoke 242, and an elastic member 243 are provided in the cavity 24, and the yoke 242 has a first yoke portion 242a and a second yoke portion 242b. In the first cavity portion 24a, the first yoke portion 242a is movable in the radial direction and the elastic member 243 is expandable and contractible, and in the second cavity portion 24b, the second yoke portion 242b is movable in the radial direction. The support portion 241 is located in the third cavity portion 24c.

[0028] The support portion 241 is provided in each of the multiple third gap portions 24c so as to fill the third gap portion 24c, and is formed so as to curve from the end face of the magnet Z to the elastic member 243. Here, the support portion 241 has a fan shape. The support portion 241 is provided between the magnet Z and the elastic member 243 inside each of the multiple gap portions 24 (i.e., the third gap portion 24c), and prevents the elastic member 243 from moving toward the magnet Z. The support portion 241 is formed of a non-magnetic material, and prevents the magnetic flux M2 generated radially outward from the magnet Z from passing between the magnet Z and the elastic member 243 without detouring around the side farther from the second gap portion 24b in the circumferential direction (so-called "short circuit").

[0029] The yoke 242 is made of a magnetic material and is provided inside each of the plurality of gaps 24 so as to be movable in the radial direction of the rotor core 21. Since centrifugal force generated by the rotation of the motor 1 acts on the yoke 242 from the radially inner side to the radially outer side, the yoke 242 moves in the radial direction by pushing against or being pushed by the elastic member 243 depending on the magnitude of the centrifugal force.

[0030] The yoke 242 has a first yoke portion 242a located closer to the magnet insertion hole 22 in the circumferential direction and a second yoke portion 242b located farther from the magnet insertion hole 22 in the circumferential direction and longer than the first yoke portion 242a in the radial direction. In FIG. 2, the boundary between the first yoke portion 242a and the second yoke portion 242b is indicated by a dashed line. The first yoke portion 242a is located closer to the magnet insertion hole 22 in the circumferential direction from the dashed line, and the second yoke portion 242b is located farther from the dashed line in the circumferential direction from the dashed line. The first yoke portion 242a is connected to the second yoke portion 242b so that its radially central end face is flush with the radially central end face of the second yoke portion 242b. The radial length of the second yoke portion 242b is greater than the radial length of the first gap portion 24a.

[0031] The elastic member 243 is a compression spring that presses the yoke 242 radially inside each of the multiple gaps 24. As shown in Fig. 2, the elastic member 243 is provided radially between the end surface S1 of the gap 24 and the first yoke portion 242a. The elastic member 243 is made of a non-magnetic material and prevents short-circuiting of the magnetic flux M2 generated radially outward from the magnet Z.

[0032] The elastic member 243 is pushed radially outward by the first yoke portion 242a as centrifugal force generated by the rotation of the motor 1 acts on the yoke 242. When the rotation speed of the motor 1 is equal to or lower than the base rotation speed, the elastic force of the elastic member 243 is greater than or equal to the centrifugal force, so the elastic member 243 does not shrink even when pushed by the yoke 242. The base rotation speed is the rotation speed at which the rotor 20 can rotate without executing field-weakening control, and is a fixed value between 3000 rpm and 5000 rpm, for example. Therefore, as shown in FIG. 2, the first yoke portion 242a and the second yoke portion 242b pushed by the elastic member 243 are in contact with the radially inner end surface S2 of the gap 24.

[0033] As described above, when the rotation speed of the motor 1 is equal to or lower than the base rotation speed, the elastic member 243 presses the yoke 242, forming a gap region R1 in the second gap portion 24b where the second yoke portion 242b is not present, preventing the passage of the magnetic flux M2 and preventing a short circuit of the magnetic flux M2. As a result, the amount of the magnetic flux M2 is small and the amount of the magnetic flux M1 is large, so that the motor 1 can increase the amount of the magnetic flux that interlinks with the coil 12 during low rotation.

[0034] Because the centrifugal force acting on yoke 242 increases as the rotation speed of rotor core 21 increases, the centrifugal force when the rotation speed of rotor core 21 exceeds the base rotation speed becomes greater than the elastic force of elastic member 243 as the rotation speed increases. Therefore, when the rotation speed of rotor core 21 exceeds the base rotation speed, the higher the rotation speed, the more elastic member 243 is pushed and contracted by the centrifugal force acting on yoke 242. When elastic member 243 contracts, second yoke portion 242b approaches radially outer end surface S3 of second gap portion 24b.

[0035] 3 is a diagram showing the configuration of gap 24 when elastic member 243 is in its most compressed state. When the rotation speed of motor 1 is high (for example, 15,000 rpm) or higher than the base rotation speed, elastic member 243 is pushed and compressed by the centrifugal force acting on yoke 242, and second yoke portion 242b comes into contact with end surface S3, as shown in FIG.

[0036] As described above, when the rotation speed of motor 1 is equal to or greater than the base rotation speed, the elastic member 243 contracts more as the rotation speed increases, and as a result, in second air gap portion 24b, the air gap region R1 becomes smaller and air gap region R2 is formed and increases as the rotation speed increases. Furthermore, the smaller the air gap region R1, the more easily magnetic flux M2 passes through second yoke portion 242b and advances radially inward of magnet Z. This increases the amount of magnetic flux M2 while decreasing the amount of magnetic flux M1. As a result, in motor 1, the amount of magnetic flux M2 (leakage magnetic flux) increases as the rotation speed of motor 1 increases. Therefore, even if the execution of field-weakening control is suppressed, the rotation speed of motor 1 can be increased, and suppressing the execution of field-weakening control can reduce loss (copper loss).

[0037] When the second yoke portion 242b and the end face S3 come into contact with each other, leakage magnetic flux traveling from the radially outer side of the end face S3 to the second yoke portion 242b enters in a direction perpendicular to the end face S3. Therefore, even if the rotation speed of the motor 1 decreases, magnetic flux continues to pass through the contact surface between the second yoke portion 242b and the end face S3, generating a force in the opposite direction to the elastic force of the elastic member 243, making it difficult for the yoke 242 to move radially inward. Therefore, the second yoke portion 242b may be positioned so as not to come into contact with the radial end face S3 of the second gap portion 24b when the elastic member 243 is most compressed.

[0038] FIG. 4 is a diagram showing the second yoke portion 242b not in contact with the end surface S3. FIG. 4 shows the elastic member 243 in its most compressed state. As shown in FIG. 4, even when the elastic member 243 is in its most compressed state, the end surface S3 and the second yoke portion 242b do not come into contact, forming a gap region R3. This configuration prevents magnetic flux from entering the second yoke portion 242b from the radially outer side in a direction perpendicular to the end surface S3. As a result, when the rotation speed of the motor 1 decreases, the yoke 242 can move radially inward in accordance with the rotation speed.

[0039] Furthermore, even when the second yoke portion 242b and the end face S3 come into contact with each other, the area of ​​the second yoke portion 242b that comes into contact with the end face S3 may be reduced. As an example, the cross-sectional area of ​​the second yoke portion 242b when cut along a plane perpendicular to the radial direction of the second yoke portion 242b may be reduced toward the radially outer end face S3 of the second gap portion 24b. FIG. 5 is a diagram showing the second yoke portion 242b with a small area of ​​contact with the end face S3. FIG. 5 shows the elastic member 243 in its most compressed state.

[0040] As shown in FIG. 5, the cross-sectional area of ​​the second yoke portion 242b, when cut along a plane perpendicular to the radial direction, decreases radially outward. Even when the elastic member 243 is fully compressed, a gap region R4 is formed between the end face S3 and the second yoke portion 242b. This configuration prevents magnetic flux from entering the second yoke portion 242b from the radially outer side in a direction perpendicular to the end face S3. Therefore, when the rotation speed of the motor 1 decreases, the yoke 242 is more likely to move radially inward in response to the rotation speed. Furthermore, the circumferential side of the second yoke portion 242b closest to the magnet Z comes into contact with the end face S3, which increases the amount of magnetic flux M2.

[0041] <Effects of Rotor 20> As described above, the rotor 20 (embedded magnet rotor) has a rotor core 21 having a plurality of magnet insertion holes 22 formed at predetermined intervals in the circumferential direction and into which magnets Z are inserted, and voids 24 communicating with one end of each of the plurality of magnet insertion holes 22, a yoke 242 provided inside each of the plurality of voids 24 so as to be movable radially of the rotor core 21, and an elastic member 243 provided inside each of the plurality of voids 24 and pressing the yoke 242 radially.

[0042] With the rotor 20 configured in this manner, when the rotation speed of the motor 1 is low, below the base rotation speed, the elastic member 243 presses against the yoke 242, forming a gap region R1 that prevents the passage of the magnetic flux M2. This increases the amount of magnetic flux M1. On the other hand, when the rotation speed of the motor 1 is high, above the base rotation speed, the centrifugal force acting on the yoke 242 causes the elastic member 243 to contract, reducing the gap region R1. This reduces the amount of magnetic flux M1 and increases the amount of magnetic flux M2. As a result, the motor 1 can increase the amount of magnetic flux M1 that interlinks with the coil 12 at low rotation speeds and increase the magnetic flux M2 at high rotation speeds, thereby increasing the rotation speed of the motor 1 and reducing losses even when suppressing field-weakening control.

[0043] The present invention has been described above using embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. For example, all or part of the device can be configured by functionally or physically distributing or integrating any unit. Furthermore, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effects of the new embodiments resulting from the combination also have the effects of the original embodiments. [Explanation of symbols]

[0044] 1 motor 10 Rotation axis 11 Stator 12 coils 20 rotors 21 Rotor core 22 Magnet insertion hole 23 Flux Barrier 24 Cavity 24a 1st cavity part 24b 2nd cavity part 24c 3rd cavity part 241 Support part 242 York 242a First yoke part 242b Second yoke part 243 Elastic Members

Claims

1. a rotor core having a plurality of magnet insertion holes formed at predetermined intervals in the circumferential direction and into which magnets are inserted, and a gap portion communicating with one end of each of the plurality of magnet insertion holes; a yoke provided in each of the plurality of gaps so as to be movable in a radial direction of the rotor core; an elastic member provided in each of the plurality of gaps and pressing the yoke in the radial direction; An embedded magnet rotor having:

2. the yoke has a first yoke portion located closer to the magnet insertion hole in the circumferential direction, and a second yoke portion located farther from the magnet insertion hole in the circumferential direction and longer than the first yoke portion in the radial direction, The elastic member is provided between the end surface of the gap portion and the first yoke portion along the radial direction. The interior permanent magnet rotor according to claim 1 .

3. the gap portion has a first gap portion located on a side closer to the magnet insertion hole portion in the circumferential direction, in which the first yoke portion is movable in the radial direction and the elastic member is expandable and contractable, and a second gap portion located on a side farther from the magnet insertion hole portion in the circumferential direction, in which the second yoke portion is movable in the radial direction, the first yoke portion and the second yoke portion pressed by the elastic member are in contact with the radially inner end surface of the gap portion; The interior permanent magnet rotor according to claim 2 .

4. When the elastic member contracts, the second yoke portion approaches the radially outer end surface of the second gap portion. The embedded magnet rotor according to claim 3 .

5. the second yoke portion is located at a position where it does not come into contact with the end surface of the second gap portion in the radial direction when the elastic member is fully compressed. The embedded magnet rotor according to claim 3 .

6. a cross-sectional area of ​​the second yoke portion when cut along a plane perpendicular to the radial direction is smaller as it approaches the radially outer end surface of the second gap portion; The embedded magnet rotor according to claim 3 .

7. When the rotation speed of the rotor core exceeds a base rotation speed, the elastic member is pushed by a centrifugal force acting on the yoke and contracts more as the rotation speed increases. The interior permanent magnet rotor according to claim 1 .

8. The magnet further includes a support portion made of a non-magnetic material, the support portion being provided between the magnet and the elastic member in each of the plurality of gaps and preventing the elastic member from moving toward the magnet. The interior permanent magnet rotor according to claim 1 .

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