JP2024066911A - Axial gap motor and air gap adjustment method - Google Patents

Abstract

[Problem] To improve air gap adjustment in an axial gap motor with a double rotor/single stator structure. [Solution] An axial gap motor having a stator, a first rotor axially facing the stator on one axial side of the stator, and a second rotor axially facing the stator on the other axial side of the stator, the motor having a reference member whose axial position relative to the stator is fixed and which rotates together with the first and second rotors, and an adjustment member capable of adjusting the axial position of the reference member relative to at least one of the first and second rotors. [Selected Figure] Figure 1

Description

The present invention relates to an axial gap motor and an air gap adjustment method.

In an axial gap motor, the stator and rotor are arranged to face each other in the axial direction with an air gap between them. The size of the air gap, which is the distance between the stator and rotor, is set to a length that allows the axial gap motor to achieve the desired performance.

However, because there are individual differences in the components that make up an axial gap motor, the size of the air gap varies from one motor to another, so it is desirable to provide a mechanism for adjusting the size of the air gap.

Patent Document 1 discloses a mechanism that can adjust the air gap between the rotor and stator in an axial gap motor with a single rotor/double stator structure, in which one rotor is sandwiched between two stators, by pushing the stator from the outside to the inside. In this adjustment mechanism, the stator uses the case that houses the stator as a reference, and adjusts the space between the stator and the case to adjust the air gap.

JP 2021-164217 A

By the way, an axial gap motor can adopt a double rotor/single stator structure, which is made up of one stator sandwiched between two rotors. With a double rotor/single stator structure, it is expected that the output will be improved more than with a single rotor/double stator structure.

However, in the case of a double rotor/single stator structure, the stator is sandwiched between two rotors, so the mechanism of Patent Document 1, which adjusts the air gap by pushing the stator from the outside, cannot be used.

It would be possible to push the rotor in from the outside, but since the case is fixed and the rotor rotates, the rotor cannot be pushed in using the case as a reference point.

In addition, if the rotor is pressed in unevenly, the rotor will become eccentric, causing vibrations during rotation. For this reason, an adjustment mechanism to eliminate eccentricity is also required.

Furthermore, if the stator is moved in the axial direction, in the case of a double rotor, the stator position will fluctuate relative to both rotors, making adjustments time-consuming.

For this reason, in the past, axial gap motors with a double rotor/single stator structure had the problem that it was difficult to adjust the air gap.

The present invention aims to improve air gap adjustment in axial gap motors with a double rotor/single stator structure.

An axial gap motor according to one aspect of the present invention is an axial gap motor having a stator, a first rotor axially facing the stator on one axial side of the stator, and a second rotor axially facing the stator on the other axial side of the stator, and also having a reference member whose axial position relative to the stator is fixed and which rotates together with the first rotor and the second rotor, and an adjustment member capable of adjusting the axial position of the reference member relative to at least one of the first rotor and the second rotor.

In one embodiment of the axial gap motor described above, the motor has bolts that fix the first rotor and the second rotor to the reference member, and the adjustment member is an adjustment screw that increases the distance between the first rotor and the second rotor and the reference member against the fixation by the bolts.

In the axial gap motor of the above embodiment, the adjustment screws are provided in multiple locations in the circumferential direction.

The axial gap motor of one embodiment described above has a shaft whose circumferential position relative to the stator is fixed, and a bearing that supports the reference member relative to the shaft.

The axial gap motor of one embodiment described above has a connecting shaft that is arranged coaxially with the shaft and can output the rotation of the first rotor and the second rotor to the outside.

An air gap adjustment method for an axial gap motor according to one aspect of the present invention is a method for adjusting an air gap of an axial gap motor having a stator, a first rotor axially facing the stator on one axial side of the stator, and a second rotor axially facing the stator on the other axial side of the stator, in which the axial gap motor has a reference member whose axial position relative to the stator is fixed and which rotates together with the first rotor and the second rotor, and the air gap is adjusted by adjusting the relative axial position of at least one of the first rotor and the second rotor and the reference member.

According to one aspect of the present invention, it is possible to improve the adjustment of the air gap in an axial gap motor with a double rotor/single stator structure.

1 is a perspective view of a motor according to a first embodiment of the present invention; 2 is a perspective view showing the motor 10 of FIG. 1 excluding the connecting shaft 50, the bolt 50a, the second rotor core 31, the bolt 33a, and the adjustment screw 34a. FIG. 2 is a perspective view of a second rotor core 31 as viewed from one axial side. 2 is a perspective view of a rotor core fixing member 80. FIG. 2 is a side cross-sectional view of the motor 10 of FIG. 1 taken along a plane perpendicular to the X-axis and passing through the central axis J. 2 is a side cross-sectional view of the motor 10 in FIG. 1 taken along a plane that is parallel to the central axis J and passes through the central axis J and the axial center of a bolt 33. 2 is a side cross-sectional view of the motor 10 in FIG. 1 taken along a plane that is parallel to the central axis J and passes through the central axis J and the axial center of an adjustment screw 34. 2 is a sectional side perspective view of the motor 10 of FIG. 1 , taken along a plane parallel to the central axis J and passing through the central axis J and the axial center of an adjustment screw 34. FIG.

Below, an axial gap motor according to an embodiment of the present invention will be described with reference to the drawings. Note that in the drawings, the scale and number of components may differ from the actual structure in order to make each component easier to understand.

In addition, in the drawings, an XYZ coordinate system is appropriately shown as a three-dimensional Cartesian coordinate system. In the XYZ coordinate system, the Z-axis direction is the direction parallel to the axial direction of the central axis J shown in FIG. 1, i.e., the direction in which the central axis J extends. The Y-axis direction is the vertical direction in FIG. 1, among the radial directions relative to the central axis J. The X-axis direction is the direction perpendicular to both the Z-axis direction and the Y-axis direction. In each of the X-axis, Y-axis, and Z-axis directions, the side indicated by the arrow in the drawing is the + side, and the opposite side is the - side.

In the following description, the positive side in the Z-axis direction (+Z side) is called "one side", and the negative side in the Z-axis direction (-Z side) is called "the other side". Note that one side and the other side are names used simply for the purpose of description, and do not limit the actual positional relationship and direction. Unless otherwise specified, the direction parallel to the central axis J (Z-axis direction) is simply called "axial direction", the radial direction centered on the central axis J is simply called "radial direction", and the circumferential direction centered on the central axis J, i.e., around the axis of the central axis J, is simply called "circumferential direction". The side approaching the central axis J in the radial direction is called the "radial inner side", and the side moving away from the central axis J is called the "radial outer side". In the circumferential direction, the clockwise side when looking from the +Z side to the -Z side is called the "circumferential one side", and the counterclockwise side is called the "circumferential other side".

In this specification, "extending in the axial direction" includes not only extending strictly in the axial direction (Z-axis direction), but also extending in a direction tilted by less than 45° with respect to the axial direction. In this specification, "extending in the radial direction" includes not only extending strictly in the radial direction, i.e., in a direction perpendicular to the axial direction (Z-axis direction), but also extending in a direction tilted by less than 45° with respect to the radial direction. In addition, "parallel" includes not only strictly parallel, but also tilted by an angle of less than 45°. In addition, "expanding in a direction perpendicular to the axial direction" includes not only strictly expanding in a direction perpendicular to the axial direction (Z-axis direction), but also expanding in a direction tilted by less than 45° with respect to the direction perpendicular to the axial direction (Z-axis direction).

First Embodiment
Fig. 1 is a perspective view of a motor according to a first embodiment of the present invention. The motor 10 in Fig. 1 is an example of an axial gap motor. The motor 10 has a shaft 71 (see Fig. 5) extending along a central axis J, a stator 20, a first rotor 40 disposed on one axial side of the stator 20, and a second rotor 30 disposed on the other axial side of the stator 20.

The motor 10 has a bracket 70 that covers the first rotor 40 from one axial side of the first rotor 40. The first rotor 40 is covered by the bracket 70 and is not exposed in FIG. 1. The bracket 70 is a substantially disk-shaped member that is coaxial with the central axis J.

The first rotor 40 has a first rotor core 41 (see FIG. 5) and a first rotor magnet 42 (see FIG. 5). The first rotor core 41 is a substantially disk-shaped member coaxial with the central axis J. One axial side surface of the first rotor core 41 faces the other axial side surface of the bracket 70. The first rotor magnet 42 is fixed to the other axial side surface of the first rotor core 41, for example, by adhesive. The other axial side surface of the first rotor magnet 42 faces the one axial side surface of the stator 20. The first rotor magnet 42 is configured by arranging multiple magnets in the circumferential direction, each of which has a sector-shaped surface perpendicular to the axial direction and a thickness in the axial direction.

The second rotor 30 has a second rotor core 31 and a second rotor magnet 32 (see FIG. 2). The second rotor core 31 is a substantially disk-shaped member coaxial with the central axis J. The other axial side surface of the second rotor core 31 is exposed on the other axial side. The second rotor magnet 32 is fixed to the one axial side surface of the second rotor core 31, for example, by adhesive. The one axial side surface of the second rotor magnet 32 faces the other axial side surface of the stator 20.

The motor 10 has a stator case 60 that houses the stator 20. The stator case 60 has a first stator case 61 that covers the stator 20 from the circumferential outside. The first stator case 61 is a substantially cylindrical member that is coaxial with the central axis J. The first stator case 61 has a through hole 61a that penetrates in the Y-axis direction on the vertical upper side. The stator 20 is cooled by a refrigerant, such as cooling oil, that is supplied into the stator case 60 through the through hole 61a.

The stator case 60 has a second stator case 63 that covers the stator 20 from one axial side. The second stator case 63 is a substantially disk-shaped member that is coaxial with the central axis J. The second stator case 63 has multiple holes that penetrate in the axial direction so that one axial end of the stator core 21 is exposed to one axial side.

The stator case 60 has a third stator case 62 that covers the stator 20 from the other axial side. The third stator case 62 is a substantially disk-shaped member that is coaxial with the central axis J. The third stator case 62 has multiple holes that penetrate in the axial direction so that the other axial end of the stator core 21 is exposed to the other axial side.

The stator case 60 has a fourth stator case 64 (see FIG. 5) that covers the stator 20 from the circumferential inside. The fourth stator case 64 is a substantially cylindrical member that is coaxial with the central axis J.

The motor 10 has a rotor core fixing member 80 (see FIG. 4). The rotor core fixing member 80 will be described in detail later. The motor 10 has bolts 33 and adjustment screws 34. A plurality of bolts 33 are provided at equal intervals in the circumferential direction coaxial with the central axis J. The bolts 33 extend in the axial direction and fix the second rotor core 31 and the rotor core fixing member 80. The bolt 33a is one of the plurality of bolts 33. The adjustment screw 34 extends in the axial direction and adjusts the distance between the second rotor core 31 and the rotor core fixing member 80. The adjustment screw 34a is one of the plurality of adjustment screws 34. The following description of the bolts 33a and the adjustment screws 34a also applies to the other bolts 33 and the other adjustment screws 34.

The motor 10 has a connecting shaft 50 and bolts 50a. A plurality of bolts 50a are provided at equal intervals in the circumferential direction coaxial with the central axis J. The connecting shaft 50 is a substantially disk-shaped member coaxial with the central axis J. The connecting shaft 50 is fixed to the rotor core fixing member 80 by the bolts 50a.

Figure 2 is a perspective view of the motor 10 in Figure 1 excluding the connecting shaft 50, bolt 50a, second rotor core 31, bolt 33a, and adjustment screw 34a. The second rotor magnet 32 is fixed to the second rotor core 31 with adhesive or the like, but in Figure 2, only the second rotor core 31 is shown removed so that the second rotor magnet 32 can be seen. The second rotor magnet 32 is composed of multiple magnets arranged in the circumferential direction.

The motor 10 has bolts 62a and bolts 62b. A plurality of bolts 62a are provided at equal intervals in the circumferential direction coaxial with the central axis J. A plurality of bolts 62b are provided at equal intervals in the circumferential direction coaxial with the central axis J. The third stator case 62 is fixed at its radial outer side to the other axial side of the first stator case 61 by bolts 62a. The third stator case 62 is fixed at its radial inner side to the other axial side of the fourth stator case 64 by bolts 62b.

The rotor core fixing member 80 has an end 81 at the other axial end. The rotor core fixing member 80 has a small diameter portion 82 on one axial side of the end 81. The outer diameter of the small diameter portion 82 is larger than the outer diameter of the end 81. The small diameter portion 82 has a bolt hole 82a on the surface on the other axial side that forms a step with the end 81. Multiple bolt holes 82a are provided at equal intervals in the circumferential direction coaxially with the central axis J.

The connecting shaft 50 has a hollow on the radially inner side on one axial side. The connecting shaft 50 fits onto the other axial side of the rotor core fixing member 80 so that the end 81 of the rotor core fixing member 80 is accommodated in the hollow on the radially inner side. The bolt 50a passes axially through the connecting shaft 50 and fits into the bolt hole 82a of the rotor core fixing member 80, fixing the connecting shaft 50 to the rotor core fixing member 80.

The rotor core fixing member 80 has a second large diameter portion 83 on one axial side of the small diameter portion 82. The outer diameter of the second large diameter portion 83 is larger than the outer diameter of the small diameter portion 82. The second large diameter portion 83 has a bolt hole 83b that penetrates in the axial direction on a surface 83a on the other axial side that is a step with the small diameter portion 82. A plurality of bolt holes 83b are provided at equal intervals in the circumferential direction coaxial with the central axis J. In addition, the second large diameter portion 83 has an abutment portion 83c on the surface 83a. A plurality of abutment portions 83c are provided at equal intervals in the circumferential direction coaxial with the central axis J.

The bolts 33 pass through the second rotor core 31 in the axial direction and fit into the bolt holes 83b of the rotor core fixing member 80, fixing the second rotor core 31 to the rotor core fixing member 80. The adjustment screws 34 pass through the second rotor core 31 in the axial direction and abut against the abutment portion 83c, as described in detail below, to adjust the distance between the rotor core fixing member 80 and the second rotor core 31, thereby adjusting the air gap.

Figure 3 is an oblique view of the second rotor core 31 as seen from one axial side. The second rotor core 31 has a housing portion 31a on one axial side in which the second rotor magnet 32 is bonded and housed.

The second rotor core 31 has a protruding portion 31b on its radially inner side that protrudes further axially than the surface on one axial side of the accommodating portion 31a. The protruding portion 31b has bolt holes 31c that pass through in the axial direction and through which bolts 33 pass. A plurality of bolt holes 31c are provided at equal intervals in the circumferential direction coaxial with the central axis J. The protruding portion 31b has screw holes 31d that pass through in the axial direction and through which adjustment screws 34 pass. A plurality of screw holes 31d are provided at equal intervals in the circumferential direction coaxial with the central axis J.

The adjustment screw 34 is an example of an adjustment member that can adjust the relative axial position of the second rotor 30 and the rotor core fixing member 80. As will be described in detail later, the adjustment screw 34 is fitted into the threaded hole 31d of the second rotor core 31 and pushed axially to one side, widening the gap between the second rotor 30 and the rotor core fixing member 80.

The first rotor 41 has the same configuration as the second rotor core 31, except that the second rotor core 31 is inverted on one side and the other side in the axial direction, so a detailed explanation is omitted.

Figure 4 is a perspective view of the rotor core fixing member 80. The rotor core fixing member 80 has a hollowed-out portion 84 on one axial side of the second large diameter portion 83. The rotor core fixing member 80 has a first large diameter portion 85 on one axial side of the hollowed-out portion 84. The outer diameter of the first large diameter portion 85 is the same as the outer diameter of the second large diameter portion 83. The rotor core fixing member 80 may have a configuration in which the first large diameter portion 85 to the second large diameter portion 83 have the same diameter continuously and do not have the hollowed-out portion 84. The hollowed-out portion 84 is a portion that has been hollowed out so that it has a smaller diameter than the first large diameter portion 85 and the second large diameter portion 83. The rotor core fixing member 80 is lightened by having the hollowed-out portion 84. The rotor core fixing member 80 is an example of a reference member whose axial position relative to the stator 20 is fixed and which rotates together with the first rotor 40 and the second rotor 30.

The first large diameter portion 85 has a bolt hole 85a that penetrates in the axial direction. A plurality of bolt holes 85a are provided at equal intervals in the circumferential direction coaxial with the central axis J. The first large diameter portion 85 also has an abutment portion 85b on a surface on one axial side. A plurality of abutment portions 85b are provided at equal intervals in the circumferential direction coaxial with the central axis J.

Figure 5 is a side cross-sectional view of the motor 10 in Figure 1 cut along a plane perpendicular to the X-axis and passing through the central axis J. Figure 6 is a side cross-sectional view of the motor 10 in Figure 1 cut along a plane parallel to the central axis J and passing through the central axis J and the axial center of the bolt 33.

The shaft 71 is a substantially cylindrical member coaxial with the central axis J. The motor 10 has bolts 70a. A plurality of bolts 70a are provided at equal intervals in the circumferential direction coaxial with the central axis J. The shaft 71 is fixed to the surface on the other axial side of the bracket 70 by the bolts 70a. In this embodiment, the shaft 71 does not rotate.

The motor 10 has bolts 70b. A plurality of bolts 70b are provided at equal intervals in the circumferential direction coaxial with the central axis J. The bolts 70b pass through the bracket 70 and the second stator case 63 in the axial direction, and fix the bracket 70 and the second stator case 63 to one axial side of the first stator case 61.

The stator 20 has a stator core 21 and a stator coil 22. A plurality of stator cores 21 are provided at equal intervals in the circumferential direction coaxial with the central axis J. One axial end of each of the plurality of stator cores 21 is exposed to one axial side from a hole penetrating the second stator case 63 in the axial direction, and faces the other axial side surface of the first rotor magnet 42 in the axial direction. The other axial end of each of the plurality of stator cores 21 is exposed to the other axial side from a hole penetrating the third stator case 62 in the axial direction, and faces the one axial side surface of the second rotor magnet 32 in the axial direction.

The rotor core fixing member 80 is supported by the shaft 71 via the bearings 71a and 71b. The rotor core fixing member 80 can rotate with respect to the shaft 71 around the central axis J as the rotation axis. As shown in FIG. 6, the rotor core fixing member 80 is fixed to the second rotor core 31 by the bolts 33. The rotor core fixing member 80 is also fixed to the first rotor core 41 by the bolts 43. Therefore, when the first rotor 40 and the second rotor 30 rotate relative to the stator 20, the rotor core fixing member 80 also rotates relative to the stator 20. Since the connecting shaft 50 is fixed to the rotor core fixing member 80, when the rotor core fixing member 80 rotates relative to the stator 20, the connecting shaft 50 also rotates. The motor 10 can output the rotation of the first rotor 40 and the second rotor 30 to the outside by the rotation of the connecting shaft 50.

Figure 7 is a side cross-sectional view of the motor 10 in Figure 1 cut along a plane parallel to the central axis J and passing through the central axis J and the axial center of the adjustment screw 34. Figure 8 is a side cross-sectional perspective view of the motor 10 in Figure 1 cut along a plane parallel to the central axis J and passing through the central axis J and the axial center of the adjustment screw 34.

The second rotor core 31 of the second rotor 30 is fixed to the rotor core fixing member 80 by the bolts 33 so that the air gap between the second rotor magnet 32 and the stator core 21 is the minimum value of the adjustable range. For example, the second rotor core 31 and the rotor core fixing member 80 are fixed by the bolts 33 at a position where the surface 31ba, which is the surface on one axial side of the protruding portion 31b of the second rotor core 31, contacts the surface 83a, which is the surface on the other axial side of the second large diameter portion 83 of the rotor core fixing member 80.

When the adjustment screw 34 is screwed into the screw hole 31d, the adjustment screw 34 penetrates the protrusion 31b from the other axial side to one axial side, and the end of the adjustment screw 34 on one axial side abuts against the abutment portion 83c of the surface 83a.

When adjusting the air gap between the second rotor magnet 32 and the stator core 21, the adjustment screw 34 is screwed further into the screw hole 31d. As a result, one axial end of the adjustment screw 34 protrudes further to one axial side than the surface 31ba, and the distance between the surface 31ba and the surface 83a is increased in the axial direction against the fixation by the bolt 33. When the distance between the surface 31ba and the surface 83a in the axial direction is increased, the air gap between the second rotor magnet 32 and the stator core 21 becomes larger.

In this way, according to this embodiment, the air gap between the second rotor magnet 32 and the stator core 21 can be adjusted according to the amount of screwing of the adjustment screw 34. A plurality of adjustment screws 34 are provided in the circumferential direction, and by adjusting the amount of screwing of each of these plurality of adjustment screws 34, eccentricity of the rotor can be suppressed and vibrations due to eccentricity during rotation can be suppressed.

The above describes the adjustment of the air gap between the second rotor magnet 32 and the stator core 21, but the same applies to the adjustment of the air gap between the first rotor magnet 42 and the stator core 21. The adjustment of the air gap between the first rotor magnet 42 and the stator core 21 can be performed, for example, by adjusting the amount of screwing of the adjustment screw 44 before attaching the bracket 70.

As described above, according to this embodiment, in an axial gap motor with a double rotor/single stator structure, the air gap can be adjusted by pressing the rotor from the outside, using the rotor core fixing member 80 as a reference.

In addition, this embodiment allows the air gap to be adjusted on the rotor side, making it possible to adjust it to eliminate eccentricity. Also, since the air gap can be adjusted separately for each rotor of the double rotor, their relative positions do not shift at the same time, and adjustment work can be reduced.

The present invention is not limited to the above-described embodiment, and various improvements and design changes may be made without departing from the spirit of the present invention. In addition, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

10...motor, 20...stator, 30...second rotor, 40...first rotor

Claims (6)

An axial gap motor having a stator, a first rotor axially facing the stator on one axial side of the stator, and a second rotor axially facing the stator on the other axial side of the stator,
a reference member whose axial position relative to the stator is fixed and which rotates together with the first rotor and the second rotor;
an adjustment member capable of adjusting a relative axial position between at least one of the first rotor and the second rotor and the reference member;
An axial gap motor having a bolt for fixing the first rotor and the second rotor to the reference member;
2. The axial gap motor according to claim 1, wherein the adjustment member is an adjustment screw that increases the gap between the first rotor and the second rotor and the reference member against the fixation by the bolt. The axial gap motor according to claim 2 , wherein a plurality of the adjustment screws are provided in the circumferential direction. A shaft whose circumferential position relative to the stator is fixed;
2. The axial gap motor according to claim 1, further comprising a bearing that supports the reference member relative to the shaft. 5. The axial gap motor according to claim 4, further comprising a coupling shaft that is coaxial with the shaft and is capable of outputting the rotation of the first rotor and the second rotor to an outside. An air gap adjustment method for an axial gap motor having a stator, a first rotor axially facing the stator on one axial side of the stator, and a second rotor axially facing the stator on the other axial side of the stator, comprising:
the axial gap motor has a reference member whose axial position relative to the stator is fixed and which rotates together with the first rotor and the second rotor;
An air gap adjustment method for adjusting the air gap by adjusting a relative axial position between at least one of the first rotor and the second rotor and the reference member.

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