WO2021010371A1 - Rotary electric machine - Google Patents

Abstract

A rotary electric machine (11, 64) comprises: a stator (14, 65) including a stator core (16, 51, 61) with a plurality of winding wires (17) wound thereon; a fixing member (12, 13, 63) to which the stator core is fixed; and a rotor (15, 67) disposed opposite the stator core and rotatably supported. The stator core includes a soft magnetic plate material (41, 54, 62) having a saturated magnetic flux density of not less than 2.0 Tesla. The stator core is provided in such a way that the soft magnetic plate material is subjected to a tensile force.

Description

Rotating electric machine Cross-reference of related applications

This application is based on Japanese Application No. 2019-130937 filed on July 16, 2019, and the contents of the description are incorporated herein by reference.

This disclosure relates to a rotary electric machine.

Conventionally, as a rotary electric machine, for example, a fixing member having a cylindrical portion, a stator in which a winding is wound around a stator core fixed inside the fixing member, and a stator inside in the radial direction of the stator core. Some are provided with a rotatably supported rotor (see, for example, Patent Document 1). The stator core of such a rotary electric machine is generally held by press fitting or press fitting to the inner peripheral surface of the fixing member.

JP 2015-186322A

In recent years, while using permanent magnets for rotors as strong neodymium magnets, etc., by using permendur plates, etc., which have a higher saturation magnetic flux density than general silicon steel plates, as materials for stator cores, It is considered to improve efficiency and eventually increase output.

However, it is known that a plate material made of permendur having a high saturation magnetic flux density significantly deteriorates magnetic properties such as magnetic permeability when a large compressive force is applied. For example, if it is fixed by pressure contact with a fixing member simply by shrink fitting or press fitting, a large compressive force is applied, the magnetic characteristics are significantly deteriorated, and there is a problem that a highly efficient rotary electric machine cannot be obtained.

The purpose of this disclosure is to provide a rotary electric machine that enables high efficiency.

In the first aspect of the present disclosure, the rotary electric machine faces a stator in which a plurality of windings are wound around a stator core, a fixing member to which the stator core is fixed, and the stator core. Includes rotors arranged and rotatably supported. The stator core includes a soft magnetic plate material having a saturation magnetic flux density of 2.0 tesla or more. The stator core is provided so that a tensile force is applied to the soft magnetic plate material.

According to the same configuration, since the stator core contains a soft magnetic plate material having a saturation magnetic flux density of 2.0 tesla or more, for example, a general soft magnetic plate material such as a silicon steel plate having a saturation magnetic flux density of less than 2.0 tesla. It is possible to obtain a rotating electric machine with higher efficiency than the one configured with only. A soft magnetic plate material having a saturation magnetic flux density of 2.0 tesla or more is significantly improved in magnetic properties such as magnetic permeability when a tensile force is applied. From this, it is possible to improve the magnetic characteristics of the stator core by providing the stator core so that a tensile force is applied to the soft magnetic plate material. Therefore, it is possible to obtain a highly efficient rotary electric machine.

The above objectives and other objectives, features and advantages of the present disclosure will be clarified by the following detailed description with reference to the accompanying drawings. The drawing is
FIG. 1 is a cross-sectional view of a rotary electric machine according to an embodiment. FIG. 2 is a partial plan view of the stator in one embodiment. FIG. 3 is a partial plan view of the rotor in one embodiment. FIG. 4 is a circuit diagram showing a circuit configuration in one embodiment. FIG. 5 is a partial cross-sectional view of the rotary electric machine according to the embodiment. FIG. 6 is a plan view of the stator in one embodiment. FIG. 7 is a plan view of the housing (fixing member) in one embodiment. FIG. 8 is a magnetic field strength-magnetic flux density characteristic diagram of the soft magnetic plate material obtained from the experimental results. FIG. 9 is a plan view of the stator in another example. FIG. 10 is a partial plan view of the stator in another example. FIG. 11 is a partial cross-sectional view of a rotary electric machine in another example. FIG. 12 is a partial cross-sectional view of the stator in another example.

Hereinafter, an embodiment of the rotary electric machine will be described with reference to FIGS. 1 to 8.

As shown in FIG. 1, the rotary electric machine 11 has a pair of housings 12 and 13 facing in the axial direction as fixing members, a substantially cylindrical stator 14 fixed to the housings 12 and 13, and a stator 14. It includes a rotor 15 rotatably supported inside in the radial direction.

The housings 12 and 13 have substantially disk-shaped disk portions 12a and 13a and cylindrical portions 12b and 13b extending in the axial direction from the outer edges of the disk portions 12a and 13a, and are at the tip portions of the cylindrical portions 12b and 13b. The stator 14 is fixed while sandwiching the stator 14.

As shown in FIGS. 1 and 2, the stator 14 has a plurality of windings 17 wound around the stator core 16. Specifically, as shown in FIG. 2, the stator core 16 has an annular yoke portion 16a and a plurality of tooth portions 16b extending inward in the radial direction from the yoke portion 16a and arranged along the circumferential direction. The winding 17 is a conductor 17a made of copper, aluminum, or the like with an enamel coating 17b applied. The windings 17 are arranged in parallel between the tooth portions 16b in the radial direction, and are held in such a manner that they are covered with the insulating paper 18.

As shown in FIG. 1, the rotor 15 has a rotating shaft 20 rotatably supported by a pair of bearings 19 fixed to the shaft centers of the pair of housings 12 and 13, and a rotation fixed to the rotating shaft 20. A child core 21 and a permanent magnet 22 fixed to the outer surface of the rotor core 21 are provided. The permanent magnet 22 is arranged so as to face the stator core 16 in the radial direction.

As shown in FIG. 3, a neodymium magnet and a Halbach array are adopted for the permanent magnet 22 of the present embodiment. The arrow shown in FIG. 3 indicates the magnetization direction of the permanent magnet 22, the base point side of the arrow corresponds to the S pole, and the end point side of the arrow corresponds to the N pole.

As shown in FIG. 4, in the plurality of windings 17, U-phase, V-phase, and W-phase windings 17 are Y-connected, and a control device 31 is connected to the terminals of the windings 17 of each phase. ing.

The control device 31 is 1) one or more processors that execute various processes according to a computer program (software), 2) an integrated circuit (ASIC) for a specific application, or the like that executes at least a part of the various processes. It can be configured as a circuitry containing one or more dedicated hardware circuits, or 3) combinations thereof. The processor includes a CPU and a memory such as a RAM and a ROM, and the memory stores a program code or an instruction configured to cause the CPU to execute a process. Memory or computer-readable media includes any available medium accessible by a general purpose or dedicated computer.

The control device 31 includes a three-phase inverter circuit 32 for generating three-phase drive power having a phase difference of 120 degrees from the DC power of the DC power source E. The three-phase inverter circuit 32 is a bridge circuit having three pairs of MOSFETs 33a, 33b, 33c, 33d, 33e, 33f connected in series between the high potential side power supply line L1 connected to the DC power supply E and the ground line GND. It is composed of. Reflux diodes D1 to D6 are connected to each of the MOSFETs 33a, 33b, 33c, 33d, 33e, and 33f, respectively.

The output terminal Su between the U-phase MOSFETs 33a and 33b is connected to the terminal of the U-phase winding 17, and the output terminal Sv between the V- phase MOSFETs 33c and 33d is connected to the terminal of the V-phase winding 17. The output terminal Sw between the W- phase MOSFETs 33e and 33f is connected to the terminal of the W-phase winding 17.

Further, the control device 31 includes a current command unit 34, and the current command unit 34 receives, for example, a command signal S from a higher-level control unit (not shown) and a rotation detection signal P of the rotor 15, respectively, of the MOSFETs 33a and 33b. Control signals are output to the gates Ga to Gf of 33c, 33d, 33e, and 33f to perform PWM control.

Here, as shown in FIGS. 1 and 5, the stator core 16 of the present embodiment is formed by laminating a soft magnetic plate material 41 having a saturation magnetic flux density of 2.0 tesla or more. The stator core 16 is provided so that a tensile force is applied to the soft magnetic plate material 41.

More specifically, first, as the soft magnetic plate material 41 constituting the stator core 16, a plate material having a permendur having a saturation magnetic flux density of about 2.3 Tesla is adopted. An insulating member made of a polyamide film, polymer paper, or the like is sandwiched between the soft magnetic plate members 41.

As shown in FIG. 5, the stator core 16 has a plurality of iron core holes 16c that penetrate in the axial direction and are arranged along the circumferential direction. The iron core hole 16c is formed in a bulging portion 16d that bulges outward in the radial direction from the yoke portion 16a of the stator core 16. Eight bulging portions 16d and iron core holes 16c of the present embodiment are formed at equal angular intervals in the circumferential direction.

Further, as shown in FIG. 7, the housings 12 and 13 have a plurality of fixing holes 12c and 13c that penetrate in the axial direction and are arranged along the circumferential direction. Eight fixing holes 12c and 13c are formed in the disk portions 12a and 13a of the housings 12 and 13 at equal angular intervals in the circumferential direction.

Then, as shown in FIG. 1, the stator core 16 is fixed to the housings 12 and 13 by the fixing holes 12c and 13c and the through bolts 42 inserted into the iron core holes 16c. The through bolt 42 of the present embodiment penetrates one fixing hole 12c and the iron core hole 16c and is screwed into a female screw formed on the inner surface of the other fixing hole 13c to form the stator core 16. It is fixed to the housings 12 and 13. Further, the through bolt 42 of the present embodiment is made of a material containing a metal having an elastic modulus higher than that of steel having an elastic modulus of about 200 GPa, and specifically, is made of molybdenum having an elastic modulus of about 320 GPa.

Then, as shown in FIGS. 5 to 7, in a state where the stator core 16 and the housings 12 and 13 are not fixed, the distance between the axis center Z of the rotor 15 and the axis center of the iron core hole 16c A certain iron core hole radius R1 is set to be smaller than the fixed hole radius R2, which is the distance between the axial center Z of the rotor 15 and the axial centers of the fixing holes 12c and 13c. Then, in a state where the stator core 16 is fixed to the housings 12 and 13 by the through bolts 42 inserted into the fixing holes 12c and 13c and the iron core holes 16c, the core holes 16c of the stator core 16 are pulled outward in the radial direction. Therefore, it is said that a tensile force is applied to the stator core 16 and the soft magnetic plate material 41. In the present embodiment, when the housings 12 and 13 made of an aluminum-based material are cooled and shrunk, the through bolt 42 is inserted into the fixing holes 12c and 13c and the iron core hole 16c, and the housings 12 and 13 return to room temperature. Since the fixed hole radius R2 is larger than the iron core hole radius R1, a tensile force is applied to the soft magnetic plate material 41.

Next, the operation of the rotary electric machine 11 configured as described above will be described.

When a three-phase drive current is supplied from the control device 31 to the winding 17 of the stator 14, a rotating magnetic field is generated in the stator 14 to rotationally drive the rotor 15. A strong neodymium magnet is used for the permanent magnet 22, but a soft magnetic plate 41, which is a plate made of permendur having a saturation magnetic flux density of 2.0 tesla or more, is used as the material of the stator core 16. Therefore, magnetic saturation can be avoided, a flow of magnetic flux without stagnation can be ensured, and the rotor 15 is rotationally driven with high efficiency.

Next, the advantages of the above embodiment will be described below.

(1) Since the stator core 16 includes a soft magnetic plate material 41 having a saturation magnetic flux density of 2.0 tesla or more, for example, only a general soft magnetic plate material such as a silicon steel plate having a saturation magnetic flux density of less than 2.0 tesla. It is possible to obtain a rotary electric machine 11 having higher efficiency than that configured in. The soft magnetic plate material 41 having a saturation magnetic flux density of 2.0 tesla or more is significantly improved in magnetic properties such as magnetic permeability when a tensile force is applied. FIG. 8 is a magnetic field strength-magnetic flux density characteristic diagram obtained from the experimental results, and the characteristic X1 of the soft magnetic plate material 41 to which the compressive force is applied is based on the characteristic X2 of the soft magnetic plate material 41 to which the compressive force is not applied. However, the magnetic flux density is significantly reduced, and the characteristic X3 of the soft magnetic plate material 41 to which a tensile force is applied indicates that the magnetic flux density is significantly improved as compared with the characteristic X2. Therefore, by providing the stator core so that a tensile force is applied to the soft magnetic plate material 41, it is possible to improve the magnetic characteristics of the stator core 16. Therefore, it is possible to obtain a highly efficient rotary electric machine 11.

(2) In a state where the housings 12 and 13 and the stator core 16 are not fixed, the iron core hole radius R1 which is the distance between the axis center Z of the rotor 15 and the axis center of the iron core hole 16c is the rotor. It is set smaller than the fixed hole radius R2, which is the distance between the shaft center Z of 15 and the shaft centers of the fixing holes 12c and 13c. Therefore, in a state where the stator core 16 is fixed to the housings 12 and 13 by the through bolts 42 inserted into the fixing holes 12c and 13c and the iron core holes 16c, the core holes 16c of the stator core 16 are pulled outward in the radial direction. As a result, a tensile force is applied to the stator core 16 and the soft magnetic plate material 41. With such a configuration, it is possible to easily and surely maintain a state in which a tensile force is applied to the soft magnetic plate material 41.

(3) Since the through bolt 42 contains a metal having a higher elastic modulus than steel having an elastic modulus of about 200 GPa and is made of molybdenum in the present embodiment, the through bolt 42 is made of steel as compared with the one made of steel. It is possible to apply a strong tensile force to the soft magnetic plate material 41, and it is possible to maintain a strong tensile force.

The above embodiment can be modified and implemented as follows. Further, the present embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.

-In the above embodiment, the stator core 16 is provided so as to apply a tensile force to the soft magnetic plate material 41 by the through bolt 42 in a state of being fixed to the housings 12 and 13, but the present invention is not limited to this and is fixed. If the saturation magnetic flux density of the soft magnetic plate material constituting the child core is 2.0 tesla or more and the stator core is provided so that a tensile force is applied to the soft magnetic plate material, the above embodiment is changed to another configuration. You may.

For example, it may be changed as shown in FIGS. 9 and 10. That is, in this example, the stator core 51 includes an annular yoke member 52 and a teeth member 53. The teeth member 53 is engaged with the yoke member 52 and extends radially inward from the yoke member 52, and the plurality of teeth portions 53a arranged along the circumferential direction and the radial inner ends of the teeth portions 53a are arranged in the circumferential direction. It has a connecting portion 53b to be connected. The yoke member 52 and the tooth member 53 are engaged with each other so that a tensile force is applied to the soft magnetic plate member 54. Specifically, first, in this example, the tooth member 53 is formed by laminating a soft magnetic plate material 54 such as permendur having a saturation magnetic flux density of 2.0 tesla or more. The yoke member 52 of this example is made by laminating a general soft magnetic plate material such as a silicon steel plate. A plurality of tab tail recesses 52a are formed inside the yoke member 52 in the radial direction at equal angular intervals in the circumferential direction. On each radial outer side of the tooth portion 53a, a tab tail convex portion 53c is formed which engages so as to be fitted into the corresponding tab tail concave portion 52a so as to restrict the movement in the radial direction. The tab tail concave portion 52a and the tab tail convex portion 53c have a substantially trapezoidal shape when viewed from the axial direction, and the tab tail convex portion 53c from the tab tail concave portion 52a is formed by engaging the inclined surfaces inclined in the radial direction with each other. Movement inward in the radial direction is restricted. The dimensions of the yoke member 52 and the tooth member 53 are set so that a tensile force is applied to the soft magnetic plate member 54 constituting the tooth member 53 in a state where the tab tail concave portion 52a and the tab tail convex portion 53c are engaged with each other. Has been done. That is, in this example, each tooth portion 53a is assembled to the yoke member 52 by fitting the tab tail convex portion 53c into the tab tail concave portion 52a while pulling each tooth portion 53a including the tab tail convex portion 53c radially outward. Each dimension is set so that a tensile force is applied to the soft magnetic plate member 54 constituting the tooth member 53 in this assembled state.

Even in this way, the state in which a tensile force is applied to the soft magnetic plate material 54 is maintained, the magnetic characteristics of the stator core 51 can be improved, and a highly efficient rotary electric machine can be obtained. Further, in this example, the tooth member 53 is made of a soft magnetic plate material 54 such as permendur having a saturation magnetic flux density of 2.0 tesla or more, and the yoke member 52 is made of a general soft magnetic plate material such as a silicon steel plate. .. Therefore, in this example, the soft magnetic plate material 54 having a saturation magnetic flux density of 2.0 tesla or more, which tends to be expensive, can be efficiently used for the teeth portion 53a to improve the efficiency of the rotary electric machine. Of course, the yoke member 52 may be made of a soft magnetic plate material other than a general soft magnetic plate material such as a silicon steel plate, or may be formed by laminating a soft magnetic plate material such as permendur.

Further, for example, the configuration shown in FIG. 11 may be adopted. That is, in this example, the stator core 61 has a cylindrical portion 61a and a plurality of teeth portions 61b extending radially outward from the cylindrical portion 61a and arranged along the circumferential direction, and has a saturation magnetic flux density of 2.0. A soft magnetic plate material 62 such as permendur of Tesla or higher is laminated. The cylindrical portion 61a of the stator core 61 is fixed to the outer periphery of the center piece 63 as a fixing member in a press-fitted state so that a tensile force is applied to the soft magnetic plate member 62. The rotary electric machine 64 of this example is an outer rotor type, and the rotor yoke 66 and the rotor 67 having a permanent magnet 22 can rotate outside the stator 65 having the stator core 61 and the winding 17 in the radial direction. It is provided in.

Even in this way, the state in which the pulling force is applied to the soft magnetic plate material 62 is maintained, the magnetic characteristics of the stator core 61 can be improved, and a highly efficient rotary electric machine 64 can be obtained.

-Although not particularly mentioned in the above embodiment, the soft magnetic plate material 41 in which the stator core 16 is laminated may be fixed in any axial direction.

For example, as shown in FIG. 12, the stator core 16 has a through hole 71 penetrating in the axial direction, and the magnetic powder 72 is filled in the through hole 71 in a compressed state to form a soft magnetic plate material. 41 may be fixed in the axial direction. The magnetic powder 72 preferably has an insulating film for each powder. In this way, it is possible to reduce the eddy current loss and improve the magnetic characteristics as compared with the case of fixing in the axial direction by, for example, caulking or welding. That is, when the soft magnetic plate members 41 are fixed to each other in the axial direction by, for example, caulking or welding, there is a possibility that an eddy current path is formed or the magnetic characteristics are deteriorated due to the application of compressive force. These can be avoided. Further, for example, especially when the soft magnetic plate material 41 is a pressed product, unevenness may occur on the inner surface of the through hole 71 due to burrs or sagging, but since the magnetic powder 72 also enters the gaps between them, it is soft. The magnetic plate material 41 is firmly fixed in the axial direction. Further, when the magnetic powder 72 also enters the gaps between the irregularities, the gaps are less likely to become magnetic resistance, and the magnetic characteristics of the stator core 16 are improved.

In the above embodiment, the through bolt 42 is inserted into the fixing holes 12c and 13c and the iron core hole 16c in a state where the housings 12 and 13 are cooled and contracted, and when the housings 12 and 13 return to room temperature, the fixing hole radius R2 becomes the iron core. A tensile force is applied to the soft magnetic plate material 41 by making the hole radius larger than R1, but the through bolt 42 may be inserted by another method.

In the above embodiment, the through bolt 42 penetrates one fixing hole 12c and the iron core hole 16c and is screwed into the female screw formed on the inner surface of the other fixing hole 13c to form the stator core 16. It is assumed that the housings 12 and 13 are fixed, but the present invention is not limited to this. For example, a female screw is not formed on the inner surface of the fixing hole 13c, and a nut may be used for fastening and fixing.

-In the above embodiment, the through bolt is made of molybdenum, but the present invention is not limited to this, and for example, the through bolt may be made of tungsten having an elastic modulus of about 340 GPa. Even in this way, the same effect as the effect (3) of the above embodiment can be obtained. Further, of course, the through bolt may be made of general steel.

-In the above embodiment, the soft magnetic plate material 41 is a plate material having a permendur having a saturation magnetic flux density of about 2.3 tesla, but the present invention is not limited to this, and the saturation magnetic flux density is 2.0 tesla or more. It may be changed to a plate material of another material.

-In the above embodiment, the permanent magnet 22 is assumed to be a neodymium magnet, but the present invention is not limited to this, and for example, other rare earth magnets or ferrite magnets may be used. Further, in the above embodiment, the permanent magnet 22 adopts the Halbach array, but the arrangement is not limited to this, and other arrangements may be used. Further, the permanent magnet 22 may be provided by being embedded in the rotor core 21. That is, the rotor 15 may be a surface magnet type or an embedded magnet type.

-The control device 31 of the above embodiment may be changed to another configuration, and may be, for example, a control device using an IGBT instead of the MOSFETs 33a, 33b, 33c, 33d, 33e, 33f.

-Although this disclosure has been described in accordance with the examples, it is understood that the disclosure is not limited to the examples and structures. The present disclosure also includes various modifications and modifications within an equal range. In addition, various combinations and forms, as well as other combinations and forms that include only one element, more, or less, are also within the scope of the present disclosure.

Claims (7)

1. A stator (14, 65) in which a plurality of windings (17) are wound around a stator core (16, 51, 61), and a stator (14, 65).
   Fixing members (12, 13, 63) to which the stator core is fixed, and
   A rotary electric machine (11,64) provided with a rotor (15,67) rotatably supported and arranged to face the stator core.
   The stator core contains a soft magnetic plate material (41, 54, 62) having a saturation magnetic flux density of 2.0 tesla or more.
   The stator core is a rotary electric machine provided so as to apply a tensile force to the soft magnetic plate material.
2. The fixing members (12, 13) have a plurality of fixing holes (12c, 13c) penetrating in the axial direction and lining up along the circumferential direction.
   The stator core (16) has a plurality of iron core holes (16c) penetrating in the axial direction and arranged along the circumferential direction.
   The stator core (16) is fixed to the fixing member by the fixing hole and a through bolt (42) inserted into the iron core hole.
   In a state where the stator core and the fixing member are not fixed, the core hole radius (R1), which is the distance between the axial center of the rotor and the axial center of the iron core hole, is the axis of the rotor. The rotary electric machine according to claim 1, wherein the rotary electric machine is set to be smaller than the fixed hole radius (R2), which is the distance between the center and the axial center of the fixed hole.
3. The rotary electric machine according to claim 2, wherein the through bolt contains a metal having a higher elastic modulus than steel.
4. The stator core (51) includes an annular yoke member (52), a plurality of teeth portions (53a) that are engaged with the yoke member, extend radially from the yoke member, and are arranged along the circumferential direction. Includes a teeth member (53) having a connecting portion (53b) that connects the teeth portions in the circumferential direction.
   The rotary electric machine according to claim 1, wherein the yoke member and the tooth member are engaged with each other so that a tensile force is applied to the soft magnetic plate material (54).
5. The rotary electric machine according to claim 4, wherein the teeth member includes a plurality of the soft magnetic plate materials having a laminated saturation magnetic flux density of 2.0 tesla or more.
6. The stator core (61) has a cylindrical portion (61a) and a plurality of teeth portions (61b) extending radially outward from the cylindrical portion and arranged along the circumferential direction.
   The rotary electric machine according to claim 1, wherein the cylindrical portion of the stator core is fixed to the outer periphery of the fixing member (63) in a press-fitted state so that a tensile force is applied to the soft magnetic plate material (62).
7. The stator core has a through hole (71) penetrating in the axial direction, and the soft magnetic plate material is axially filled by filling the through hole with the magnetic powder (72) in a compressed state. Fixed,
   The rotary electric machine according to any one of claims 1 to 6, wherein the magnetic powder has an insulating film for each powder.

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