Rotor and switched reluctance motor

Abstract

The goal is to reduce rotor iron loss while minimizing cost increases and torque density decreases. [Solution] The rotor 3 is rotatably arranged around a rotation axis 2 and includes a rotor core 10 made of a first magnetic material, first salient poles 21 made of the first magnetic material formed at predetermined intervals in the circumferential direction of the rotor core 10 on the outer circumferential surface of the rotor core 10, second salient poles 22 made of a second magnetic material having less iron loss than the first magnetic material and provided radially outward of the rotor core 10 on the first salient poles 21, and a stopper 23 made of an insulating material that engages with the first salient poles 21 and the second salient poles 22.

Description

Technical Field

[0001] The present invention relates to a rotor and a switched reluctance motor.

Background Art

[0002] The switched reluctance motor (hereinafter referred to as "SR motor") of Patent Document 1 has a stator formed in a cylindrical shape by laminating annular electromagnetic steel sheets, and a rotor formed in a cylindrical shape and disposed inside the stator in the radial direction. The stator has a plurality of stator teeth formed on its inner circumference, and the rotor has a plurality of rotor teeth formed on its outer circumference.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the SR motor, torque is generated by the rotation of the rotor so that the reluctance of the coil corresponding to the excited phase among the coils wound around each stator tooth becomes small. Since the poles at the time of magnetization of each stator tooth are fixed, the poles of each rotor tooth change according to the poles of the stator tooth to which the rotor tooth is close. As a result, the hysteresis loss (so-called iron loss) of the rotor increases. On the other hand, a measure of forming the rotor using a material with low iron loss can be taken, but in the rotor using this material, the cost is high or the torque density decreases.

[0005] Therefore, the present invention has been made in view of these points, and an object thereof is to reduce the iron loss of the rotor while suppressing an increase in cost and a decrease in torque density.

Means for Solving the Problems

[0006] A rotor according to a first aspect of the present invention is rotatably arranged around a rotation axis and comprises a rotor core made of a first magnetic material, first salient poles made of the first magnetic material and formed at predetermined intervals in the circumferential direction of the rotor core on the outer circumferential surface of the rotor core, second salient poles made of a second magnetic material having less iron loss than the first magnetic material and provided radially outward of the rotor core at the first salient poles, and a stopper made of an insulating material that engages with the first salient pole and the second salient pole.

[0007] The first salient pole has a wedge-shaped projection formed on a surface along the radial direction of the rotor core, and the stopper may be engaged with the projection.

[0008] The second salient pole is shorter the further it is from the outer surface of the rotor core in the circumferential direction, and the stopper may engage with the radially aligned surface of the rotor core at the second salient pole.

[0009] The first salient pole may have a wedge-shaped projection formed on the surface that contacts the second salient pole, and the second salient pole may have a wedge-shaped recess formed on the surface that contacts the first salient pole, with the recess of the second salient pole fitting with the projection of the first salient pole.

[0010] The first salient pole may have a wedge-shaped recess formed on the surface that contacts the second salient pole, and the second salient pole may have a wedge-shaped protrusion formed on the surface that contacts the first salient pole, and the protrusion of the second salient pole may be fitted into the recess of the first salient pole.

[0011] The stopper may be provided so as to contact two opposing surfaces of adjacent first salient poles, two opposing surfaces of adjacent second salient poles provided radially outward of the first salient poles, and the outer circumferential surface between adjacent first salient poles.

[0012] The stopper may fill the space between adjacent first salient poles and between adjacent second salient poles.

[0013] A switch reluctance motor according to a second aspect of the present invention is a switch reluctance motor including a rotor and a stator, wherein the rotor is rotatably arranged about a rotation axis and includes a rotor core made of a first magnetic material, first salient poles made of the first magnetic material and formed at predetermined first intervals in the circumferential direction of the rotor core on the outer circumferential surface of the rotor core, second salient poles provided radially outward of the rotor core at the first salient poles and made of a second magnetic material having less iron loss than the first magnetic material, and stoppers made of an insulating material that engage with the first and second salient poles, wherein the stator includes a stator core arranged on the outer diameter side of the rotor, and teeth portions formed at predetermined second intervals in the circumferential direction of the stator core on the inner circumferential surface of the stator core, each of which has a winding of one of a plurality of phase windings wound around it. [Effects of the Invention]

[0014] According to the present invention, the effect of reducing rotor iron loss is achieved while suppressing increases in cost and decreases in torque density. [Brief explanation of the drawing]

[0015] [Figure 1] This is a diagram showing the overview of motor 1. [Figure 2] This is an enlarged view of section P of the cross-sectional view of rotor 3. [Figure 3] This figure shows a stopper 23 filling the space between adjacent salient poles 20. [Modes for carrying out the invention]

[0016] <Overview of Motor 1> Figure 1 is a diagram illustrating the overview of motor 1. Figure 1 shows a cross-sectional view of motor 1 cut by a plane perpendicular to the axial direction of the rotation shaft 2. Motor 1 is a switched reluctance motor (SR motor) and comprises a rotation shaft 2, a rotor 3, and a stator 4.

[0017] The rotor 3 is a rotor located on the outer diameter side of the rotating shaft 2 and the inner diameter side of the stator 4, and has a rotor core 10, a plurality of salient poles 20, and a plurality of stoppers 23. In Figure 1, only one of the plurality of salient poles 20 is labeled with a reference numeral, and only the stopper 23 that is in contact with the labeled salient pole 20 is labeled with a reference numeral. The rotor core 10 is rotatably mounted in the rotational direction (circumferential direction) of the rotating shaft 2, and is formed in a cylindrical shape by stacking annular magnetic material in the axial direction, for example. The salient poles 20 have a first salient pole 21 and a second salient pole 22, and protrude radially from the outer circumference of the rotor core 10. The salient poles 20 are made of a magnetic material, and the first salient pole 21 is formed integrally with the rotor core 10. The stoppers 23 are made of an insulating material and engage the first salient pole 21 and the second salient pole 22.

[0018] The stator 4 is a stator located on the outer diameter side of the rotor 3 and has a stator core 30, a plurality of teeth 40, and a plurality of coils 50. In Figure 1, only one of the plurality of teeth 40 and one of the plurality of coils 50 are labeled with reference numerals.

[0019] The stator core 30 is located on the outer diameter side of the rotor 3 and is formed in a cylindrical shape by, for example, stacking annular magnetic material in the axial direction. The teeth 40 are made of magnetic material and are formed on the inner circumferential surface of the stator core 30 at predetermined intervals in the circumferential direction of the stator core 30. The predetermined interval is the interval at which multiple teeth 40 are formed at equal intervals in the circumferential direction. Each tooth 40 has a coil 50 of one of the multiple phases of coil 50 wound around it. In Figure 1, six phases are shown as multiple phases: phase A, phase B, phase C, phase D, phase E, and phase F, and the tooth 40 labeled with a reference numeral has a coil 50 of phase A wound around it.

[0020] The motor 1 generates torque by rotating the rotor 3 so that the reluctance of the coil 50 corresponding to the excited phase (the phase with a large reluctance) among the coils 50 wound around each tooth portion 40 becomes small. In the motor 1, the driving circuit (not shown) excites the phase with a large reluctance, which changes as the rotor 3 rotates, so that the rotor 3 continues to rotate.

[0021] In the motor 1, since the rotor 3 rotates, an alternating magnetic field is generated in the rotor 3 and the stator 4, resulting in iron loss (hysteresis loss, eddy current loss). In the stator 4, since the poles (S pole or N pole) of each tooth portion 40 are fixed, hysteresis loss occurs due to the repetition of the non-magnetized state and the magnetized state. On the other hand, in the rotor 3, since the poles of the salient poles 20 change according to the poles of the adjacent tooth portions 40, hysteresis loss occurs due to the repetition of the magnetized state of the S pole and the magnetized state of the N pole, and this hysteresis loss is larger than the hysteresis loss generated in the stator 4. Furthermore, since the frequency of the alternating magnetic field in the rotor 3 is higher than the frequency of the alternating magnetic field in the stator 4, the iron loss in the rotor 3 is larger than the iron loss in the stator 4.

[0022] In contrast, a strategy can be taken to form the rotor 3 from a low-iron-loss material with low iron loss, such as a silicon steel sheet of a thin plate (for example, with a plate thickness of 100 μm or less), an amorphous crystalline metal, or a powder material in which the surface of each metal powder is coated with resin. However, the silicon steel sheet of a thin plate and the amorphous crystalline metal are more costly than the silicon steel sheet, which is not a thin plate and is a conventional material for forming the conventional rotor 3 and stator 4. In addition, the rotor 3 made of a powder material has insufficient strength against the force applied by rotation, so the rotational speed of the rotor 3 cannot be increased. Furthermore, the low-iron-loss material may have a lower torque density due to a lower saturation magnetic flux density than the conventional material.

[0023] Therefore, the rotor 3 has a first salient pole 21 made of a conventional material formed on the outer circumferential surface of the rotor core 10, and a second salient pole 22 made of a low iron loss material provided radially outward from the rotor core 10 at the first salient pole. With this configuration, the rotor 3 has the second salient pole 22 made of a low iron loss material at a position where iron loss is large (a position where the teeth portion 40 and the salient pole 20 are close together), thus suppressing iron loss. Furthermore, since the rotor core 10 and the first salient pole 21 of the rotor 3 are formed using conventional materials, the increase in cost and decrease in torque density can be suppressed compared to constructing the entire rotor 3 from a low iron loss material. In addition, the stopper 23 engages the first salient pole 21 and the second salient pole 22, preventing the second salient pole 22 from separating from the first salient pole 21 even when centrifugal force and magnetic stress due to the rotation of the rotor 3 act on the second salient pole 22. The configuration of rotor 3 will be explained in detail below.

[0024] <Configuration of Rotor 3> As shown in Figure 1, the rotor 3 has a rotor core 10, a plurality of salient poles 20, and a plurality of stoppers 23, with each salient pole 20 having a first salient pole 21 and a second salient pole 22, and stoppers 23 are provided between adjacent salient poles 20. The rotor core 10 is rotatably arranged around the rotation axis 2 and is made of a first magnetic material. The first magnetic material is a conventional material such as a silicon steel sheet that is not a thin sheet.

[0025] The first salient poles 21 are formed on the outer circumferential surface of the rotor core 10, made of a first magnetic material, at predetermined intervals in the circumferential direction of the rotor core 10. The predetermined intervals are such that multiple first salient poles 21 are formed at equal intervals in the circumferential direction of the rotor core 10. The first salient poles 21 protrude radially from the outer circumferential surface of the rotor core 10, and wedge-shaped protrusions are formed on the radial surface and the top surface. The rotor core 10 and the first salient poles 21 are formed as a single unit. As described above, by having a rotor core 10 and first salient poles 21 made of a first magnetic material, the rotor 3 can suppress increases in cost and decreases in torque density.

[0026] The second salient pole 22 is provided radially outward from the rotor core 10 in the first salient pole 21 and is made of a second magnetic material that has lower iron loss than the first magnetic material. The second salient pole 22 is in contact with the top surface of the second salient pole 21, and a wedge-shaped recess is formed on the surface in contact with the top surface. The second magnetic material is, for example, a thin silicon steel sheet, an amorphous crystalline metal, or a powder material with low iron loss. With the second salient pole 22 configured in this way, the rotor 3 can be provided with the second salient pole 22 made of a low iron loss material in a position where the teeth portion 40 and the salient pole 20, which have high iron loss, are close together. As a result, the rotor 3 can suppress iron loss.

[0027] The stopper 23 is made of an insulating material and engages with the first salient pole 21 and the second salient pole 22. The insulating material forming the stopper 23 is a non-magnetic and insulating material, such as a ceramic or resin material. The stopper 23 engages with the two first salient poles 21 and the two second salient poles 22 that are in contact with each other in the circumferential direction of the rotor core 10. With the stopper 23 configured in this way, even if centrifugal force and magnetic stress due to the rotation of the rotor 3 act on the second salient poles 22, it is possible to prevent the second salient poles 22 from separating from the first salient poles 21. The configurations of the first salient pole 21, the second salient pole 22, and the stopper 23 will be described in detail below.

[0028] Figure 2 is an enlarged view of a portion P of the cross-sectional view of the rotor 3 shown in Figure 1. In the following explanation, we will focus on the configuration of salient pole 20a shown in Figure 2, among the multiple salient poles 20 of the rotor 3, and the configuration of stopper 23a shown in Figure 2, among the multiple stoppers 23 of the rotor 3. Note that the configuration of salient poles 20 other than salient pole 20a is the same as the configuration of salient pole 20a, and the configuration of stopper 23 other than stopper 23a is the same as the configuration of stopper 23a.

[0029] As shown in Figure 2, the first salient pole 21a has a wedge-shaped first protrusion 211a formed on the surface S1a that contacts the second salient pole 22a. Surface S1a is the top surface of the first salient pole 21a. The second salient pole 22a has a wedge-shaped recess 222a formed on the surface S2a that contacts the first salient pole 21a, and the recess 222a is fitted with the first protrusion 211a. The lengths of the first protrusion 211a and the recess 222a in the circumferential direction of the rotor core 10 are formed to become longer the further they are from the rotor core 10. With this configuration, even if centrifugal force and magnetic stress due to the rotation of the rotor 3 act on the second salient pole 22, the second salient pole 22 is less likely to separate from the first salient pole 21.

[0030] The first salient pole 21a has a wedge-shaped second protrusion formed on a surface along the radial direction of the rotor core 10, and the stopper 23 engages with this second protrusion. Specifically, the first salient pole 21a has a wedge-shaped second protrusion 213a formed on surface S3a and a wedge-shaped second protrusion 214a formed on surface S4a.

[0031] The second protrusion 213a is formed so as not to include the end of the radial surface S3a of the rotor core 10, and the second protrusion 214a is formed so as not to include the end of the radial surface S4a of the rotor core. The second protrusions 213a and 214a protrude more in the circumferential direction of the rotor core 10 the further they are from the top surface of the first salient pole 21. The second protrusions 213a and 214a may be formed such that the position where they protrude most significantly in the circumferential direction of the rotor core 10 (i.e., the tip) is closest to the rotor core 10.

[0032] Furthermore, stopper 23a engages with the second protrusion 213a, and stopper 23c engages with the second protrusion 214a. With this configuration, even if centrifugal force and magnetic stress due to the rotation of rotor 3 act on stopper 23, stopper 23 is less likely to come off radially outward from rotor core 10.

[0033] The second salient pole 22a is formed such that its circumferential length relative to the rotor core 10 decreases as it moves further away from the outer surface of the rotor core 10. Specifically, the second salient pole 22a has a tapered shape. The stopper 23a engages with the surface S5a of the second salient pole 22a that is aligned with the radial direction of the rotor core 10, and the stopper 23c engages with the surface S6a of the second salient pole 22a that is aligned with the radial direction of the rotor core 10. With this configuration, even if centrifugal force and magnetic stress due to the rotation of the rotor 3 act on the second salient pole 22, the second salient pole 22 is less likely to separate from the first salient pole 21.

[0034] The stopper 23 is provided so as to contact two opposing faces of adjacent first salient poles 21, two opposing faces of adjacent second salient poles 22 provided radially outward of the first salient poles 21, and the outer circumferential surface between adjacent first salient poles 21. The two opposing faces of adjacent first salient poles 21 are, for example, face S3a of the first salient pole 21a and face S4b of the first salient pole 21b. The two opposing faces of adjacent second salient poles 22 are, for example, face S5a of the second salient pole 22a and face S6b of the second salient pole 22b. The outer circumferential surface between adjacent first salient poles 21 is, for example, the outer circumferential surface R.

[0035] As an example, as shown in Figure 2, the stopper 23a is provided so as to contact surfaces S3a, S4b, S5a, S6b and the outer peripheral surface R, and has a U-shaped cross-section perpendicular to the axial direction of the rotation axis 2. With this configuration, recesses are formed on the contact surfaces with surface S3a and S4b of the stopper 23a, so that it fits into the second protrusion 213a and the wedge-shaped second protrusion 214b formed on the surface of the rotor core 10 along the radial direction of the first salient pole 21b. As a result, even if centrifugal force and magnetic stress due to the rotation of the rotor 3 act on the stopper 23a, it is possible to prevent the stopper 23a from coming off radially outward of the rotor core 10.

[0036] The stopper 23 shown in Figures 1 and 2 has a U-shaped cross-section perpendicular to the axial direction of the rotation axis 2, but is not limited to this. The stopper 23 may fill the space between adjacent first salient poles 21 and between adjacent second salient poles 22. Figure 3 shows a stopper 23 that fills the space between adjacent salient poles 20. As shown in Figure 3, the stopper 23a may be formed to fill the space between the first salient pole 21a and the first salient pole 21b and the space between the second salient pole 22a and the second salient pole 22b. This configuration increases the rigidity of the stopper 23, making it easier to form the stopper 23 using an insulating material with low strength.

[0037] <First variation> In the above explanation, the configuration is illustrated as an example where motor 1 is a 10-saliency pole, 12-slot SR motor, but it is not limited to this. Motor 1 may be an SR motor other than the 10-saliency pole, 12-slot type (for example, an 8-saliency pole, 12-slot SR motor).

[0038] <Second variation> In the above description, an example configuration was given in which the first salient pole 21 has a wedge-shaped protrusion on the surface that contacts the second salient pole 22, and the second salient pole 22 has a wedge-shaped recess on the surface that contacts the first salient pole, but the invention is not limited to this configuration. The first salient pole 21 may have a wedge-shaped recess formed on the surface that contacts the second salient pole 22, and the second salient pole 22 may have a wedge-shaped protrusion formed on the surface that contacts the first salient pole 21, with the protrusion of the second salient pole 22 fitting into the recess of the first salient pole 21. With this configuration, the rotor 3 can have a larger volume of the second salient pole 22 made of low iron loss material than the rotor 3 shown in Figure 1. As a result, it becomes easier to reduce the iron loss caused by the rotation of the rotor 3.

[0039] <Effects of Rotor 3> As described above, the rotor 3 is rotatably arranged around the rotation axis 2 and includes a rotor core 10 made of a first magnetic material, first salient poles 21 made of the first magnetic material formed at predetermined intervals in the circumferential direction of the rotor core 10 on the outer circumferential surface of the rotor core 10, second salient poles 22 made of a second magnetic material having less iron loss than the first magnetic material and provided radially outward of the rotor core 10 on the first salient poles 21, and stoppers 23 made of an insulating material that engage with the first salient poles 21 and the second salient poles 22.

[0040] With the rotor 3 configured in this way, a second salient pole 22 made of a low-iron-loss material can be provided in a position where the teeth 40 and the salient pole 20 are close together, which tends to increase iron loss. Therefore, the rotor 3 can suppress iron loss. Furthermore, since the rotor core 10 and the first salient pole 21 can be formed from conventional materials that are less expensive than low-iron-loss materials and have a higher saturation magnetic flux density, an increase in cost and a decrease in torque density can be suppressed. In addition, by engaging the stopper 23 with the first salient pole 21 and the second salient pole 22, the second salient pole 22 can be prevented from separating from the first salient pole 21 even when centrifugal force and magnetic stress due to the rotation of the rotor 3 act on the second salient pole 22.

[0041] Although the present invention has been described above using embodiments, 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 its gist. For example, all or part of the apparatus can be configured by functionally or physically distributing and integrating in 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 combinations are combined with the effects of the original embodiments. [Explanation of Symbols]

[0042] 1 motor 2 rotation axes 3 rotors 4 stata 10 rotor cores 20 salient pole 20a salient pole 20b salient pole 21 1st salient pole 21a 1st salient pole 21b 1st salient pole 22 Second salient pole 22a 2nd salient pole 22b 2nd salient pole 23 Stopper 23a Stopper 23c Stopper 30 stator cores 40 Teeth section 50 coils 211a First protrusion 213a Second protrusion 214a Second protrusion 214b Second protrusion 222a Recess

Claims

1. A rotor core made of a first magnetic material is arranged to be rotatable around a rotation axis, On the outer circumferential surface of the rotor core, there are first salient poles made of the first magnetic material and formed at predetermined intervals in the circumferential direction of the rotor core, A second salient pole is provided radially outward from the rotor core in the first salient pole and is made of a second magnetic material having less iron loss than the first magnetic material, It has a stopper made of an insulating material that engages with the first salient pole and the second salient pole, Rotor.

2. The first salient pole has a wedge-shaped protrusion formed on the surface of the rotor core along the radial direction. The stopper engages with the protrusion. The rotor according to claim 1.

3. The second salient pole is shorter the further it is from the outer surface of the rotor core, as its circumferential length from the rotor core. The stopper engages with a surface of the rotor core along the radial direction in the second salient pole. The rotor according to claim 1.

4. The first salient pole has a wedge-shaped protrusion formed on the surface that contacts the second salient pole. The second salient pole has a wedge-shaped recess formed on the surface that contacts the first salient pole. The recess of the second salient pole is fitted with the protrusion of the first salient pole. The rotor according to claim 1.

5. The first salient pole has a wedge-shaped recess formed on the surface that contacts the second salient pole. The second salient pole has a wedge-shaped protrusion formed on the surface that contacts the first salient pole. The protrusion of the second salient pole is fitted into the recess of the first salient pole. The rotor according to claim 1.

6. The stopper is provided so as to contact two opposing surfaces of adjacent first salient poles, two opposing surfaces of adjacent second salient poles provided radially outward of the first salient poles, and the outer circumferential surface between adjacent first salient poles. The rotor according to claim 1.

7. The stopper fills the space between adjacent first salient poles and between adjacent second salient poles. The rotor according to claim 6.

8. A switched reluctance motor including a rotor and a stator, The rotor is A rotor core made of a first magnetic material is arranged to be rotatable around a rotation axis, On the outer circumferential surface of the rotor core, there are first salient poles made of the first magnetic material and formed at predetermined first intervals in the circumferential direction of the rotor core, A second salient pole is provided radially outward from the rotor core in the first salient pole and is made of a second magnetic material having less iron loss than the first magnetic material, It has a stopper made of an insulating material that engages with the first salient pole and the second salient pole, The stator is, A stator core positioned on the outer diameter side of the rotor, The inner circumferential surface of the stator core has teeth formed at predetermined second intervals in the circumferential direction of the stator core, each of which has a winding of one of the multiple phase windings wound around it. Switched reluctance motor.

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