Axial gap motor and air gap adjustment method

Abstract

To improve adjustment of an air gap in an axial gap motor having a double rotor / single stator structure.SOLUTION: An axial gap motor includes: a stator; a first rotor facing the stator in an axial direction at one axial side of the stator; and a second rotor facing the stator in the axial direction at the other axial side of the stator. The axial gap motor has: a reference member whose axial position relative to the stator is fixed and which rotates with the first rotor and the second rotor; and an adjustment member which may adjust a relative axial position between at least one of the first rotor and the second rotor and the reference member.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an axial gap motor and an air gap adjustment method.

Background Art

[0002] In an axial gap motor, a stator and a rotor are arranged so as to face each other in the axial direction through an air gap. The size of the air gap, which is the distance between the stator and the rotor, is set to a length at which the desired performance of the axial gap motor is exhibited.

[0003] However, due to individual differences in the components constituting the axial gap motor, etc., individual differences occur in the size of the air gap, so it is desired to provide a mechanism for adjusting the size of the air gap.

[0004] In Patent Document 1, in an axial gap motor having a single rotor - double stator structure in which one rotor is sandwiched between two stators, a mechanism capable of adjusting the air gap between the rotor and the stator by pushing the stator from the outside to the inside is disclosed. In this adjustment mechanism, the stator adjusts the air gap by adjusting the distance between the stator and the case that houses the stator, with the case as a reference.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Incidentally, an axial gap motor can employ a double-rotor, single-stator structure, which consists of a single stator sandwiched between two rotors. This double-rotor, single-stator structure is expected to provide better output than a single-rotor, double-stator structure.

[0007] However, in the case of a double rotor, single stator structure, the stator is sandwiched between the two rotors, so the mechanism described in Patent Document 1, which adjusts the air gap by pushing the stator from the outside, cannot be used.

[0008] One might consider pushing the rotor in from the outside, but since the case is fixed while the rotor is rotating, the rotor cannot be pushed in using the case as a reference point.

[0009] Furthermore, uneven pressure on the rotor can cause eccentricity, leading to vibrations during rotation. Therefore, an adjustment mechanism to eliminate eccentricity is also required.

[0010] Furthermore, if the stator is moved axially, in the case of a double rotor, the stator position will fluctuate relative to either rotor, making adjustment time-consuming.

[0011] Therefore, conventional axial gap motors with a double rotor and single stator structure have had the problem of being difficult to adjust the air gap.

[0012] The present invention aims to improve the adjustment of the air gap in an axial gap motor with a double rotor and single stator structure. [Means for solving the problem]

[0013] An axial gap motor according to one aspect of the present invention is an axial gap motor having a stator, a first rotor facing the stator in the axial direction on one axial side of the stator, and a second rotor facing the stator in the axial direction on the other axial side of the stator, wherein the axial gap motor has a fixed relative axial position to the stator and rotates together with the first rotor and the second rotor, and an adjustment member that can adjust the relative axial position between at least one of the first rotor and the second rotor and the reference member. Bolts for fixing the first rotor and the second rotor to the reference member, to have The adjustment member is an adjustment screw that widens the gap between the first rotor and the second rotor and the reference member against the fixing by the bolt. .

[0015] In the axial gap motor according to the above embodiment, the adjustment screws are provided in multiple locations in the circumferential direction.

[0016] In the axial gap motor according to one embodiment described above, the motor comprises a shaft whose relative circumferential position to the stator is fixed, and a bearing that pivotally supports the reference member with respect to the shaft.

[0017] In the axial gap motor according to one embodiment described above, there is a connecting shaft provided coaxially with the shaft, which is capable of outputting the rotation of the first rotor and the second rotor to an external source.

[0018] An air gap adjustment method for an axial gap motor according to one aspect of the present invention is an air gap adjustment method for an axial gap motor having a stator, a first rotor facing the stator in the axial direction on one axial side of the stator, and a second rotor facing the stator in the axial direction on the other axial side of the stator, wherein the axial gap motor has a reference member whose relative axial position with respect to the stator is fixed and which rotates together with the first rotor and the second rotor, bolts for fixing the first rotor and the second rotor to the reference member, and an adjustment member capable of adjusting the relative axial position between at least one of the first rotor and the second rotor and the reference member, wherein the adjustment member is an adjustment screw that widens the gap between the first rotor and the second rotor and the reference member against the fixing by the bolts. The aforementioned adjustment screwThe 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.

Advantages of the Invention

[0019] According to one aspect of the present invention, in an axial gap motor having a double rotor - single stator structure, the adjustment of the air gap can be improved.

Brief Description of the Drawings

[0020] [Figure 1] It is a perspective view of the motor according to the first embodiment of the present invention. [Figure 2] It is a perspective view showing the motor 10 of FIG. 1 excluding the splicing shaft 50, the bolt 50a, the second rotor core 31, the bolt 33a, and the adjustment screw 34a. [Figure 3] It is a perspective view of the second rotor core 31 seen from one axial side. [Figure 4] It is a perspective view of the rotor core fixing member 80. [Figure 5] It is a side cross - sectional view showing the motor 10 of FIG. 1 cut along a plane perpendicular to the X - axis and passing through the central axis J. [Figure 6] It is a side cross - sectional view showing the motor 10 of FIG. 1 cut along a plane parallel to the central axis J and passing through the central axis J and the axis center of the bolt 33. [Figure 7] It is a side cross - sectional view showing the motor 10 of FIG. 1 cut along a plane parallel to the central axis J and passing through the central axis J and the axis center of the adjustment screw 34. [Figure 8] It is a side cross - sectional perspective view showing the motor 10 of FIG. 1 cut along a plane parallel to the central axis J and passing through the central axis J and the axis center of the adjustment screw 34.

Embodiments for Carrying out the Invention

[0021] The following description of an axial gap motor according to an embodiment of the present invention will be made with reference to the drawings. Note that in the following drawings, the scale and number of components in each structure may differ from the actual structure in order to make the components easier to understand.

[0022] Furthermore, in the drawings, the XYZ coordinate system is shown as a three-dimensional Cartesian coordinate system where appropriate. In the XYZ coordinate system, the Z-axis direction is the direction of the central axis J shown in Figure 1, that is, the direction parallel to the direction in which the central axis J extends. The Y-axis direction is the radial direction relative to the central axis J, specifically the up and down direction in Figure 1. The X-axis direction is the direction perpendicular to both the Z-axis and Y-axis directions. In all 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.

[0023] Furthermore, in the following explanation, the positive side in the Z-axis direction (+Z side) will be referred to as "one side," and the negative side in the Z-axis direction (-Z side) will be referred to as "the other side." Note that "one side" and "the other side" are merely names used for explanatory purposes and do not limit the actual positional relationship or direction. Unless otherwise specified, the direction parallel to the central axis J (Z-axis direction) will be simply referred to as the "axis direction," the radial direction centered on the central axis J will be simply referred to as the "radial direction," and the circumferential direction centered on the central axis J, i.e., around the axis of the central axis J, will be simply referred to as the "circumferential direction." In the radial direction, the side approaching the central axis J will be referred to as the "inside radial direction," and the side moving away from the central axis J will be referred to as the "outside radial direction." In the circumferential direction, the clockwise side when viewed from the +Z side to the -Z side will be referred to as the "one side circumferential," and the counterclockwise side will be referred to as the "other side circumferential."

[0024] In this specification, "extending in the axial direction" includes not only cases where the extension is strictly in the axial direction (Z-axis direction), but also cases where the extension is inclined in a direction with an angle of less than 45° relative to the axial direction. Furthermore, in this specification, "extending in the radial direction" includes not only cases where the extension is strictly in the radial direction, i.e., perpendicular to the axial direction (Z-axis direction), but also cases where the extension is inclined in a direction with an angle of less than 45° relative to the radial direction. Furthermore, "parallel" includes not only cases where the extension is strictly parallel, but also cases where the angle between them is inclined in a range of less than 45°. Furthermore, "spreading in a direction perpendicular to the axial direction" includes not only cases where the extension spreads in a direction perpendicular to the axial direction (Z-axis direction), but also cases where the extension spreads in a direction with an angle of less than 45° relative to the direction perpendicular to the axial direction (Z-axis direction).

[0025] <First Embodiment> Figure 1 is a perspective view of a motor according to a first embodiment of the present invention. The motor 10 in Figure 1 is an example of an axial gap motor. The motor 10 includes a shaft 71 (see Figure 5) extending along a central axis J, a stator 20, a first rotor 40 positioned on one axial side of the stator 20, and a second rotor 30 positioned on the other axial side of the stator 20.

[0026] 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 not exposed in Figure 1 because it is covered by the bracket 70. The bracket 70 is a substantially disc-shaped member coaxial with the central axis J.

[0027] The first rotor 40 has a first rotor core 41 (see Figure 5) and a first rotor magnet 42 (see Figure 5). The first rotor core 41 is a substantially disc-shaped member coaxial with the central axis J. One axial surface of the first rotor core 41 faces the other axial surface of the bracket 70. The first rotor magnet 42 is fixed to the other axial surface of the first rotor core 41, for example, by adhesive. The other axial surface of the first rotor magnet 42 faces the one axial surface of the stator 20. The first rotor magnet 42 is constructed by arranging a plurality of magnets in the circumferential direction, each magnet having a fan shape on a surface perpendicular to the axial direction and thickness in the axial direction.

[0028] The second rotor 30 has a second rotor core 31 and a second rotor magnet 32 ​​(see Figure 2). The second rotor core 31 is a substantially disc-shaped member coaxial with the central axis J. The other axial surface of the second rotor core 31 is exposed on the other axial side. The second rotor magnet 32 ​​is fixed to one axial surface of the second rotor core 31, for example, by adhesive. The one axial surface of the second rotor magnet 32 ​​faces the other axial surface of the stator 20.

[0029] 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 outside in the circumferential direction. The first stator case 61 is a substantially cylindrical member 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 vertically upward side. The stator 20 is cooled by a coolant, such as cooling oil, supplied into the stator case 60 through the through hole 61a.

[0030] 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 disc-shaped member coaxial with the central axis J. The second stator case 63 has a plurality of holes that penetrate axially so that one axial end of the stator core 21 is exposed on that axial side.

[0031] 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 disc-shaped member coaxial with the central axis J. The third stator case 62 has a plurality of holes that penetrate axially so that the other axial end of the stator core 21 is exposed on the other axial side.

[0032] The stator case 60 has a fourth stator case 64 (see Figure 5) that covers the stator 20 from the inside in the circumferential direction. The fourth stator case 64 is a substantially cylindrical member coaxial with the central axis J.

[0033] The motor 10 has a rotor core fixing member 80 (see Figure 4). Details of the rotor core fixing member 80 will be described later. The motor 10 has bolts 33 and adjustment screws 34. Multiple bolts 33 are provided at equal intervals in the circumferential direction coaxial with the central axis J. The bolts 33 extend axially and fix the second rotor core 31 and the rotor core fixing member 80. Bolt 33a is one of the multiple bolts 33. The adjustment screws 34 extend axially and adjust the distance between the second rotor core 31 and the rotor core fixing member 80. Adjustment screw 34a is one of the multiple adjustment screws 34. The following descriptions of bolts 33a and adjustment screws 34a are also applicable to the other bolts 33 and adjustment screws 34.

[0034] The motor 10 has a connecting shaft 50 and bolts 50a. Multiple bolts 50a are provided at equal intervals in the circumferential direction coaxial with the central axis J. The connecting shaft 50 is a substantially disc-shaped member coaxial with the central axis J. The connecting shaft 50 is fixed to the rotor core fixing member 80 by bolts 50a.

[0035] 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 so that the second rotor magnet 32 ​​is visible. The second rotor magnet 32 ​​is constructed by arranging multiple magnets in the circumferential direction.

[0036] The motor 10 has bolts 62a and bolts 62b. Multiple bolts 62a are provided at equal intervals in the circumferential direction coaxial with the central axis J. Multiple bolts 62b are provided at equal intervals in the circumferential direction coaxial with the central axis J. The third stator case 62 is fixed to the other axial side of the first stator case 61 by bolts 62a on its radially outer side. The third stator case 62 is fixed to the other axial side of the fourth stator case 64 by bolts 62b on its radially inner side.

[0037] The rotor core fixing member 80 has an end portion 81 at the other end in the axial direction. The rotor core fixing member 80 has a small-diameter portion 82 on one side in the axial direction of the end portion 81. The outer diameter of the small-diameter portion 82 is larger than the outer diameter of the end portion 81. The small-diameter portion 82 has bolt holes 82a on the other side in the axial direction, which is a step between it and the end portion 81. Multiple bolt holes 82a are provided at equal intervals in the circumferential direction coaxial with the central axis J.

[0038] The connecting shaft 50 has a hollow radially inward side on one axial side. The connecting shaft 50 fits into the other axial side of the rotor core fixing member 80 so that the end portion 81 of the rotor core fixing member 80 is housed in the radially inward hollow of the connecting shaft 50. The bolt 50a passes through the connecting shaft 50 axially 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.

[0039] 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 bolt holes 83b that penetrate in the axial direction on the other axial side surface 83a, which is a step between it and the small diameter portion 82. Multiple bolt holes 83b are provided at equal intervals in the circumferential direction coaxial with the central axis J. The second large diameter portion 83 also has abutment portions 83c on the surface 83a. Multiple abutment portions 83c are provided at equal intervals in the circumferential direction coaxial with the central axis J.

[0040] The bolt 33 penetrates the second rotor core 31 axially and fits into the bolt hole 83b of the rotor core fixing member 80, thereby fixing the second rotor core 31 to the rotor core fixing member 80. The adjustment screw 34, as will be described in more detail later, penetrates the second rotor core 31 axially and abuts against the abutment portion 83c, adjusting the distance between the rotor core fixing member 80 and the second rotor core 31, thereby adjusting the air gap.

[0041] Figure 3 is a perspective view of the second rotor core 31 from one axial side. The second rotor core 31 has a housing portion 31a on one axial side for bonding and housing the second rotor magnet 32.

[0042] The second rotor core 31 has a projection 31b on its radially inward side that protrudes to one axial side beyond the axial side surface of the housing portion 31a. The projection 31b has a bolt hole 31c that penetrates axially and through which a bolt 33 passes. Multiple bolt holes 31c are provided at equal intervals in the circumferential direction coaxial with the central axis J. The projection 31b also has a screw hole 31d that penetrates axially and through which an adjustment screw 34 passes. Multiple screw holes 31d are provided at equal intervals in the circumferential direction coaxial with the central axis J.

[0043] The adjustment screw 34 is an example of an adjustment member that can adjust the relative axial position between the second rotor 30 and the rotor core fixing member 80. As will be described in more detail later, the adjustment screw 34 fits into the screw hole 31d of the second rotor core 31 and is pushed in one axial direction, thereby widening the gap between the second rotor 30 and the rotor core fixing member 80.

[0044] Since the first rotor 41 has the same configuration as the second rotor core 31 except that it is inverted on one axial side and the other side, a detailed explanation will be omitted.

[0045] Figure 4 is a perspective view of the rotor core fixing member 80. The rotor core fixing member 80 has a weight-reducing 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 weight-reducing 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 also have a configuration in which the first large diameter portion 85 to the second large diameter portion 83 are continuously the same diameter and do not have a weight-reducing portion 84. The weight-reducing portion 84 is a portion that has been reduced in diameter to be smaller than the first large diameter portion 85 and the second large diameter portion 83. The rotor core fixing member 80 is made lighter by having a weight-reducing portion 84. The rotor core fixing member 80 is an example of a reference member whose relative axial position to the stator 20 is fixed and which rotates together with the first rotor 40 and the second rotor 30.

[0046] The first large-diameter portion 85 has bolt holes 85a that penetrate in the axial direction. Multiple 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 abutment portions 85b on one side in the axial direction. Multiple abutment portions 85b are provided at equal intervals in the circumferential direction coaxial with the central axis J.

[0047] Figure 5 is a side cross-section of the motor 10 in Figure 1, cut by a plane perpendicular to the X-axis and passing through the central axis J. Figure 6 is a side cross-section of the motor 10 in Figure 1, cut by a plane parallel to the central axis J and passing through the axial centers of the central axis J and the bolt 33.

[0048] The shaft 71 is a substantially cylindrical member coaxial with the central axis J. The motor 10 has bolts 70a. Multiple bolts 70a are provided at equal intervals in the circumferential direction coaxial with the central axis J. The shaft 71 is fixed to the other axial side of the bracket 70 by the bolts 70a. In this embodiment, the shaft 71 does not rotate.

[0049] The motor 10 has bolts 70b. Multiple 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, fixing the bracket 70 and the second stator case 63 to one side of the first stator case 61 in the axial direction.

[0050] The stator 20 has a stator core 21 and a stator coil 22. Multiple 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 multiple stator cores 21 is exposed on one axial side through 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 multiple stator cores 21 is exposed on the other axial side through 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.

[0051] The rotor core fixing member 80 is pivotally supported on the shaft 71 via bearings 71a and 71b. The rotor core fixing member 80 is rotatable relative to the shaft 71 with its central axis J as the axis of rotation. As shown in Figure 6, the rotor core fixing member 80 is fixed to the second rotor core 31 by bolts 33. The rotor core fixing member 80 is also fixed to the first rotor core 41 by 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 this connecting shaft 50.

[0052] Figure 7 is a side cross-section of the motor 10 in Figure 1, cut by a plane parallel to the central axis J and passing through the axial centers of the central axis J and the adjustment screw 34. Figure 8 is a side cross-sectional perspective view of the motor 10 in Figure 1, cut by a plane parallel to the central axis J and passing through the axial centers of the central axis J and the adjustment screw 34.

[0053] The second rotor core 31 of the second rotor 30 is fixed to the rotor core fixing member 80 by bolts 33 such that the air gap between the second rotor magnet 32 ​​and the stator core 21 is at the minimum value within the adjustable range. For example, the second rotor core 31 and the rotor core fixing member 80 are fixed by bolts 33 at a position where the surface 31ba, which is the axial side surface of the protruding portion 31b of the second rotor core 31, is in contact with the surface 83a, which is the axial side surface of the second large diameter portion 83 of the rotor core fixing member 80.

[0054] 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 the one axial side, and the axial end of the adjustment screw 34 abuts against the abutment portion 83c of the surface 83a.

[0055] When adjusting the air gap between the second rotor magnet 32 ​​and the stator core 21, the adjustment screw 34 is further screwed into the screw hole 31d. This causes one axial end of the adjustment screw 34 to protrude axially beyond the surface 31ba, widening the gap between the surface 31ba and the surface 83a in the axial direction against the fixing by the bolt 33. As the axial gap between the surface 31ba and the surface 83a widens, the air gap between the second rotor magnet 32 ​​and the stator core 21 increases.

[0056] As described above, 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 the adjustment screw 34 is screwed in. Multiple adjustment screws 34 are provided in the circumferential direction, and by adjusting the amount each of these adjustment screws 34 is screwed in, rotor eccentricity can be suppressed and vibrations caused by eccentricity during rotation can be reduced.

[0057] The adjustment of the air gap between the second rotor magnet 32 ​​and the stator core 21 has been described above, but the same procedure applies to adjusting the air gap between the first rotor magnet 42 and the stator core 21. The air gap between the first rotor magnet 42 and the stator core 21 can be adjusted, for example, by adjusting the amount the adjustment screw 44 is screwed in before attaching the bracket 70.

[0058] As described above, according to this embodiment, in an axial gap motor with a double rotor and single stator structure, the air gap can be adjusted by pushing the rotor from the outside with the rotor core fixing member 80 as a reference.

[0059] Furthermore, according to this embodiment, by enabling adjustment of the air gap on the rotor side, it becomes possible to adjust to eliminate eccentricity. In addition, since the air gap can be adjusted individually for each rotor of the double rotor, their relative positions do not shift simultaneously, thus reducing the effort required for adjustment.

[0060] The present invention is not limited to the embodiments described above, and various improvements and design modifications may be made without departing from the spirit of the invention. In addition, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the above description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0061] 10...Motor, 20...Stator, 30...Second rotor, 40...First rotor

Claims

1. An axial gap motor having a stator, a first rotor facing the stator in the axial direction on one axial side of the stator, and a second rotor facing the stator in the axial direction on the other axial side of the stator, A reference member whose relative axial position to the stator is fixed and which rotates together with the first rotor and the second rotor, An adjustment member capable of adjusting the relative axial position between at least one of the first rotor and the second rotor and the reference member, Bolts for fixing the first rotor and the second rotor to the reference member, It has, The adjustment member is an adjustment screw that widens the distance between the first rotor and the second rotor and the reference member against the fixing by the bolt. Axial gap motor.

2. Multiple adjustment screws are provided in the circumferential direction. The axial gap motor according to claim 1.

3. A shaft whose relative circumferential position to the stator is fixed, The bearing that pivotally supports the reference member with respect to the shaft The axial gap motor according to claim 1.

4. The connecting shaft is provided coaxially with the aforementioned shaft and is capable of outputting the rotation of the first rotor and the second rotor to an external source. The axial gap motor according to claim 3.

5. A method for adjusting the air gap of an axial gap motor having a stator, a first rotor facing the stator in the axial direction on one axial side of the stator, and a second rotor facing the stator in the axial direction on the other axial side of the stator, The axial gap motor includes a reference member whose axial position relative to the stator is fixed and which rotates together with the first rotor and the second rotor, Bolts for fixing the first rotor and the second rotor to the reference member, An adjustment member capable of adjusting the relative axial position between at least one of the first rotor and the second rotor and the reference member, It has, The adjustment member is an adjustment screw that widens the distance between the first rotor and the second rotor and the reference member against the fixing by the bolt, The air gap is adjusted by adjusting the relative axial position between at least one of the first rotor and the second rotor and the reference member using the adjustment screw. How to adjust the air gap.

Images