JP7840323B2 - Axial gap motor, and method for manufacturing an axial gap motor - Google Patents

Description

This disclosure relates to an axial gap motor and a method for manufacturing an axial gap motor.
This application claims priority under Japanese Patent Application No. 2021-086466, dated May 21, 2021, and incorporates all the provisions of the said Japanese application.

The axial gap type rotating electric machine described in Patent Document 1 comprises a case, a stator, a rotor, a shaft, and bearings, as shown in Figure 10 of Patent Document 1. The case comprises a cylindrical peripheral wall and a pair of disc-shaped plates. The pair of plates are attached to both ends of the peripheral wall. A through hole is formed in the center of the pair of plates. A shaft is provided in the through hole. The stator and rotor are arranged facing each other in the axial direction of the shaft within the case. The stator is positioned on the plates. The rotor is provided with a gap between it and the stator. The shaft is the axis of rotation of the rotor. The bearings rotatably support the shaft.

Japanese Patent Publication No. 2020-108323

The axial gap motor of this disclosure is
Rotor and,
A stator is positioned with a gap of design length in the direction of rotation of the rotor,
The shaft which is the rotation axis of the rotor,
The first bearing rotatably supports the aforementioned shaft,
A case having a first plane on which the stator is mounted,
The system comprises an adjusting member that supports the first bearing,
The adjustment member has a screw thread that is screw-connected to the case,
The first bearing moves in the axial direction of the shaft due to the rotation of the adjusting member.

The method for manufacturing an axial gap motor according to this disclosure is:
The process of preparing the parts for the axial gap motor,
The process includes assembling the aforementioned parts,
The aforementioned parts are,
Rotor and,
stator and,
The shaft which is the rotation axis of the rotor,
A bearing that rotatably supports the aforementioned shaft,
A case having a first plane on which the stator is mounted,
The case includes an adjustment member that supports the bearing by being screw-connected to the case,
The stator is,
A stator core having a yoke and multiple teeth,
Each of the plurality of teeth has a coil,
In the process of assembling the aforementioned parts, the adjustment member is rotated relative to the case, causing the shaft to be raised and lowered via the bearing, thereby setting the length of the gap between the rotor and the stator to the design length.
The amount of rotation of the adjustment member is determined based on the induced voltage value generated in the coil.

Figure 1 is a schematic cross-sectional view showing the outline of an axial gap motor according to Embodiment 1. Figure 2 is a schematic cross-sectional view showing an enlarged view of region A in Figure 1. Figure 3 is a schematic cross-sectional view showing an enlarged example of another region A in Figure 1. Figure 4 is a schematic cross-sectional view showing an enlarged view of region B in Figure 1. Figure 5 is a schematic cross-sectional view showing an enlarged view of region C in Figures 2 and 3. Figure 6 is a schematic cross-sectional view illustrating the manufacturing method of an axial gap motor according to Embodiment 1. Figure 7 is a graph showing the changes in the induced voltage value. Figure 8 is a graph showing the changes in the induced voltage value. Figure 9 is a schematic cross-sectional view illustrating a modified method for manufacturing an axial gap motor. Figure 10 is a schematic plan view showing the general layout of a circuit board. Figure 11 is a schematic cross-sectional view showing an enlarged portion of the axial gap motor according to Embodiment 2.

[Issues this disclosure aims to address]
There is a need to improve the manufacturability of axial gap motors, which offer superior assembly precision.

One of the objectives of this disclosure is to provide an axial gap motor with excellent assembly precision. Another objective of this disclosure is to provide a method for manufacturing the above-mentioned axial gap motor with excellent manufacturability.

[Effects of this disclosure]
The axial gap motor disclosed herein offers excellent assembly precision.

The method for manufacturing the axial gap motor of this disclosure offers excellent manufacturability for the axial gap motor of this disclosure.

Description of Embodiments in this Disclosure
An axial gap motor is manufactured through two assembly processes: a preliminary assembly and a final assembly of the axial gap motor parts. The reason for the preliminary assembly is that it is difficult to determine the design length of the gap between the stator and rotor with only one assembly. The design length of the gap is the target value of the gap length determined based on the specifications of the axial gap motor. Therefore, the gap length of the axial gap motor manufactured through the preliminary assembly is measured. The difference between the measured gap length and the design length of the gap is calculated. After determining the measured gap length, the axial gap motor is disassembled.

The parts are assembled using a shim with the same thickness as the above difference. The shim is placed between the bearing and the plate. The placement of the shim causes the bearing to move away from the plate by the thickness of the shim. This shift in the bearing's position causes the shaft supported by the bearing to shift in the axial direction of the shaft. This shift causes the rotor to move away from the stator. This shift in the rotor causes the gap length to become longer than the measured length. In other words, the gap length becomes longer than the measured length by the thickness of the shim. Since the thickness of the shim is the same as the above difference, the gap length can be set to the design length.

The manufacturing method described above involves two assembly steps for the parts, making the manufacturing process more complicated. Furthermore, this method increases the number of parts due to the shims. Additionally, the use of shims may increase mechanical losses due to increased bearing preload.

The inventors diligently studied methods for manufacturing axial gap motors without using shims. As a result, the inventors have developed a manufacturing method that allows the gap length between the stator and rotor to be substantially the same as the design length by assembling the parts only once. The embodiments of this disclosure will be described first.

(1) An axial gap motor according to one aspect of the present disclosure is
Rotor and,
A stator is positioned with a gap of design length in the direction of rotation of the rotor,
The shaft which is the rotation axis of the rotor,
The first bearing rotatably supports the aforementioned shaft,
A case having a first plane on which the stator is mounted,
The system comprises an adjusting member that supports the first bearing,
The adjustment member has a screw thread that is screw-connected to the case,
The first bearing moves in the axial direction of the shaft due to the rotation of the adjusting member.

The above axial gap motor offers excellent assembly precision. During the manufacturing process, rotating the adjustment member relative to the case moves the first bearing in the axial direction of the shaft. Since the shaft is supported by the first bearing, the axial movement of the first bearing moves the shaft in the axial direction. As the shaft is the rotation axis of the rotor, the axial movement of the shaft moves the rotor in the axial direction. In other words, the rotor can be easily moved to a position where the gap length is equal to the design length. Since the adjustment member and the case are screw-connected, the rotor will not move in the axial direction unless the adjustment member is rotated. Therefore, the rotor is positioned at a position where the gap length is equal to the design length.

The above axial gap motor does not have shims, thus suppressing an increase in the number of parts. Furthermore, because the above axial gap motor can suppress an increase in the preload of the first bearing, it can suppress an increase in mechanical losses.

(2) In the axial gap motor described in (1) above,
The pitch of the threads of the adjusting member may be 2.5 mm or less.

The above-mentioned axial gap motor offers excellent assembly precision because the gap length can be easily adjusted using the adjustment member.

(3) In the axial gap motor described in (1) or (2) above,
The shaft is rotatably supported, and a second bearing is positioned opposite the first bearing with the rotor in between,
The system may also include an elastic member that presses the second bearing toward the first bearing.

The above-mentioned axial gap motor makes it easier to suppress play in the screw-connected portion between the case and the adjustment member.

(4) In any of the axial gap motors described in (1) to (3) above,
The first bearing is a radial bearing having an inner race and an outer race.
The adjusting member may support the outer race without contacting the inner race.

The above-described axial-gap type motor can suppress the increase in mechanical losses. This is because friction does not increase since the adjustment member does not come into contact with the inner race.

(5) In the axial gap motor described in (4) above,
A washer may be placed between the outer race and the adjustment member.

In the above-described axial gap motor, the washer is positioned between the outer race and the adjustment member, making it easier for the adjustment member to support the bearing. Furthermore, the adjustment member in the above-described axial gap motor can also be made of a solid body. This is because even if the adjustment member is made of a solid body, the washer can prevent contact between the adjustment member and the inner race. Therefore, even if the adjustment member in the above-described axial gap motor is made of a solid body, an increase in mechanical loss can be suppressed.

(6) In any of the axial gap motors described in (1) to (5) above,
The stator is,
A stator core having a yoke configured in the shape of an annular plate, and a plurality of teeth provided to protrude from the yoke,
Each of the plurality of teeth has a coil,
The stator core may be fixed to the first plane.

The above-mentioned axial gap motor offers superior assembly precision for both double-stator, single-rotor and single-stator, single-rotor motors.

(7) In the axial gap motor described in (6) above,
The stator core may be made of a compacted powder body.

The above-mentioned axial gap motor exhibits superior assembly precision even when equipped with a stator core made of a compacted powder molded body, which has lower dimensional accuracy than a stator core made of electromagnetic steel sheet.

(8) In any of the axial gap motors described in (1) to (6) above,
The number of stators and rotors may each be one.

The above axial gap motor is a single-stator, single-rotor type. The above axial gap motor boasts excellent assembly precision.

(9) A method for manufacturing an axial gap motor according to one aspect of the present disclosure is:
The process of preparing the parts for the axial gap motor,
The process includes assembling the aforementioned parts,
The aforementioned parts are,
Rotor and,
stator and,
The shaft which is the rotation axis of the rotor,
A bearing that rotatably supports the aforementioned shaft,
A case having a first plane on which the stator is mounted,
The case includes an adjustment member that supports the bearing by being screw-connected to the case,
The stator is,
A stator core having a yoke and multiple teeth,
Each of the plurality of teeth has a coil,
In the process of assembling the aforementioned parts, the adjustment member is rotated relative to the case, causing the shaft to be raised and lowered via the bearing, thereby setting the length of the gap between the rotor and the stator to the design length.
The amount of rotation of the adjustment member is determined based on the induced voltage value generated in the coil.

The above-described method for manufacturing an axial gap motor allows the rotor position to be adjusted by raising and lowering the shaft using an adjustment member. Therefore, with this method, the gap length can be set to the designed length by assembling the parts only once. Thus, this method for manufacturing an axial gap motor offers excellent manufacturability for axial gap motors with superior assembly precision, even without using shims.

Details of the embodiments of this disclosure
The embodiments of this disclosure are described below. The same reference numerals in the figures indicate the same parts.

Embodiment 1
[Axial gap motor]
The axial gap motor 1 of Embodiment 1 will be described with reference to Figures 1 to 5. Figure 1 is a cross-sectional view of the axial gap motor 1 cut by a plane parallel to the axial direction of the shaft 4. Figure 1 illustrates a single-stator, single-rotor type axial gap motor 1. A single-stator, single-rotor type axial gap motor 1 is a motor in which there is one stator 2 and one rotor 3. The axial gap motor 1 is a motor in which the stator 2 and rotor 3 face each other with a gap in the axial direction of the shaft 4.

The axial gap motor 1 of this embodiment comprises a stator 2, a rotor 3, a shaft 4, a first bearing 51, and a case 7. The axial gap motor 1 has the stator 2, rotor 3, and shaft 4 housed within the case 7. The stator 2 and rotor 3 within the case 7 face each other with a gap in the axial direction of the shaft 4. The length of this gap along the axial direction satisfies the design length G1. The design length G1 is a target value for the design gap length determined based on the specifications of the axial gap motor 1. The design length G1 has a certain tolerance. One of the features of the axial gap motor 1 of this embodiment is the inclusion of an adjustment member 6 screw-connected to the case 7.

[Stata]
As shown in Figure 1, the stator 2 is positioned on the first plane 71f of the case 7. As shown in Figure 1, the stator 2 comprises a stator core 21 and a plurality of coils 25.

(Stator core)
The stator core 21 comprises an annular plate-shaped yoke 22 and a plurality of columnar teeth 23.

<yoke>
The yoke 22 magnetically connects adjacent teeth 23 among the teeth 23 arranged in the circumferential direction of the yoke 22. As shown in Figure 2, the yoke 22 has a planar first surface 22f, a planar second surface 22s, an outer surface, and an inner surface. The first surface 22f and the second surface 22s are surfaces that connect the outer surface and the inner surface. The first surface 22f is in contact with the first plane 71f. The second surface 22s is a surface that connects to the side surface of the teeth 23.

<Teeth>
As shown in Figure 1, each tooth 23 is provided with a coil 25. There are multiple teeth 23. Each tooth 23 is arranged at a predetermined interval in the circumferential direction of the yoke 22. Each tooth 23 protrudes perpendicularly to the second surface 22s of the yoke 22, as shown in Figure 2. In this embodiment, each tooth 23 and the yoke 22 are made from a single compacted molded body. Each tooth 23 has the same shape and size. Each tooth 23 is either prismatic or cylindrical. Each tooth 23 has a side surface and an end surface 23a. The side surface is the surface connected to the second surface 22s of the yoke 22. The end surface 23a is the surface connected to the side surface. The end surface 23a faces the magnet 35 of the rotor 3, which will be described later.

<Hole>
As shown in Figure 1, the stator core 21 has a hole. A fastening member 91 is provided in this hole. The fastening member 91 fixes the stator core 21 to the first plane 71f. The fastening member 91 suppresses misalignment between the stator 2 and the first plane 71f. An example of the fastening member 91 is a screw or a bolt. The hole is formed extending from the first surface 22f to the middle of the teeth 23. The number of holes may be less than the number of teeth 23, or it may be the same as the number of teeth 23.

<Materials>
The compacted powder body that constitutes the stator core 21 is composed of an aggregate of multiple coated particles 24 as shown in Figure 4. The coated particles 24 have metal particles 241 and an insulating coating 242.

• Metal particles The metal particles 241 are composed of a soft magnetic material. The soft magnetic material is pure iron or an iron-based alloy.

Pure iron is defined as having a purity of 99% or higher. That is, pure iron is defined as having an iron (Fe) content of 99% by mass or more. The saturation magnetic flux density of pure iron is higher than that of iron-based alloys. Therefore, if the metal particles 241 of a powder compact are composed of pure iron, the saturation magnetic flux density of the powder compact tends to improve. Furthermore, pure iron has superior formability compared to iron-based alloys. Therefore, if the metal particles 241 of a powder compact are composed of pure iron, the relative density of the powder compact tends to increase.

An iron-based alloy is a material containing additive elements, with the remainder being Fe and unavoidable impurities. Iron-based alloys contain the most Fe. An iron-based alloy is, for example, at least one selected from the group consisting of Fe-Si (silicon) alloys, Fe-Al (aluminum) alloys, Fe-Si-Al alloys, and Fe-Ni (nickel) alloys. An example of an Fe-Si alloy is silicon steel. An example of an Fe-Si-Al alloy is Sendust. An example of an Fe-Ni alloy is permalloy. The electrical resistance of an iron-based alloy is greater than that of pure iron. Therefore, iron-based alloys easily reduce iron losses such as eddy current losses. Thus, if the metal particles 241 of the compacted body are composed of an iron-based alloy, the losses of the compacted body are easily reduced. The compacted body may contain both metal particles 241 composed of pure iron and metal particles 241 composed of an iron-based alloy.

- Insulating coating The insulating coating 242 covers the metal particles 241. The insulating coating 242 can reduce iron losses such as eddy current losses. A compacted molded body equipped with an insulating coating 242 is more prone to loss reduction. The material of the insulating coating 242 is, for example, an oxide. Examples of oxides include phosphate, silica, magnesium oxide, or aluminum oxide. Phosphates have excellent adhesion to the metal particles 241 and also have excellent deformability. Therefore, if the insulating coating 242 is composed of phosphate, the insulating coating 242 is more likely to deform in accordance with the deformation of the metal particles 241 during the manufacturing process of the compacted molded body. Thus, the insulating coating 242 is less prone to damage. Because the insulating coating 242 is less prone to damage, the loss of the compacted molded body is more easily reduced.

<Relative density>
The relative density of the compacted body may be 90% or higher. Compacted bodies with a relative density of 90% or higher tend to have improved saturation magnetic flux density. Compacted bodies with a relative density of 90% or higher tend to have improved mechanical properties such as strength. The relative density may be 93% or higher, and even 95% or higher. The relative density may be 99% or lower. Compacted bodies with a relative density of 99% tend to have stable induced voltage values when measured in the manufacturing method described later.

The "relative density of a compacted material" refers to the ratio (%) of the actual density of the compacted material to its true density. That is, the relative density of a compacted material is calculated as [(actual density of the compacted material / true density of the compacted material) × 100]. The actual density of a compacted material can be determined by immersing it in oil to impregnate it, and then calculating [oil-impregnated density × (mass of the compacted material before oil impregnation / mass of the compacted material after oil impregnation)]. The oil-impregnated density is (mass of the compacted material after oil impregnation / volume of the compacted material after oil impregnation). That is, the actual density of a compacted material can be calculated as (mass of the compacted material before oil impregnation / volume of the compacted material after oil impregnation). The volume of the compacted material after oil impregnation can typically be measured by the liquid displacement method. The true density of a compacted material is the theoretical density assuming no internal voids.

(coil)
Each coil 25 has a cylindrical portion. The cylindrical portion is constructed by winding a wire spirally. The coil 25 in this embodiment is an edgewise wound coil. Coated flat wire is used for the winding of the coil 25. Each coil 25 is arranged on the outer circumference of the side surface of the teeth 23. The cross-sectional shape of the cylindrical portion of each coil 25 corresponds, for example, to the cross-sectional shape of the teeth 23. The axial length of the cylindrical portion is slightly shorter than the length of the teeth 23. Note that in Figure 1, only the cylindrical portion is shown, and both ends of the winding are omitted from the illustration.

[Rota]
The rotor 3 is provided with a gap between it and the stator 2. The rotor 3 comprises a rotor body 31 and at least one magnet 35.

(Rotor body)
The rotor body 31 is rotatably supported relative to the case 7 by the shaft 4. The rotor body 31 is an annular member. The rotor body 31 has a through hole in the center. The third shaft portion 43 of the shaft 4, which will be described later, is provided in this through hole. In this embodiment, the rotor body 31 and the shaft 4 are assembled by press-fitting the shaft 4 into the through hole. Because it is press-fitted, the runout of the rotor 3 tends to be small. The position of the rotor body 31 along the axial direction of the shaft 4 is determined by the rotor body 31 abutting against the second end face 42s of the second shaft portion 42, which will be described later.

As shown in Figure 2, the rotor body 31 has a first surface 31f, a second surface 31s, an inner circumferential surface, and an outer circumferential surface. The first surface 31f and the second surface 31s connect the inner circumferential surface and the outer circumferential surface. The first surface 31f is the surface facing the stator 2. The second surface 31s is the surface facing the second bearing 55 shown in Figure 1. The second bearing 55 will be described later. In this embodiment, a recess 32 is provided on the first surface 31f. The recess 32 opens toward the stator 2. A magnet 35 is fixed to the bottom surface 32a of the recess 32. The inner circumferential surface of the rotor body 31 is in contact with the third shaft portion 43 of the shaft 4. As shown in Figure 1, the outer circumferential surface of the rotor body 31 is not in contact with the inner circumferential surface of the peripheral wall portion 73 of the case 7. A gap is provided between the outer circumferential surface of the rotor body 31 and the inner circumferential surface of the peripheral wall portion 73 of the case 7.

(magnet)
The magnet 35 is fixed to the rotor body 31. As shown in Figure 2, adhesive 38 is used to fix the magnet 35. There may be one magnet 35 or multiple magnets. If there is one magnet 35, the number of parts is fewer compared to when there are multiple magnets 35, making it easier to manufacture the rotor 3. Therefore, it is easier to improve the manufacturability of the axial gap motor 1. Moreover, it is easier to manufacture an axial gap motor 1 with excellent assembly precision.

When there is only one magnet 35, the shape of the magnet 35 is annular. The single magnet 35 has alternating south and north poles arranged in the circumferential direction. When there are multiple magnets 35, the specific number of magnets 35 is the same as the number of teeth 23. Multiple magnets 35 are arranged at equal intervals in the circumferential direction of the rotor body 31. The shape of each magnet 35 is, for example, a flat plate. The planar shape of each magnet 35 is, for example, the same as the planar shape of the end face 23a of the teeth 23. Each magnet 35 is magnetized in the axial direction of the rotation axis of the rotor 3. The magnetization directions of adjacent magnets 35 in the circumferential direction of the rotor body 31 are opposite to each other. The rotor 3 rotates as the magnets 35 repeatedly attract and repel each tooth 23 due to the rotating magnetic field generated by the stator 2.

Magnet 35 is a permanent magnet. Specific examples of permanent magnets include ferrite magnets, neodymium magnets, samarium-cobalt magnets, or bonded magnets. Neodymium magnets and samarium-cobalt magnets, in particular, have strong magnetic forces.

[shaft]
The shaft 4 is the axis of rotation of the rotor 3. The shaft 4 is made of a solid round rod. As shown in Figure 1, the shaft 4 has multiple shaft portions with different outer diameters. The multiple shaft portions are integrally formed. In this embodiment, the shaft 4 has, in order from the first plate portion 71 toward the second plate portion 72 of the case 7, a first shaft portion 41, a second shaft portion 42, a third shaft portion 43, a fourth shaft portion 44, and a fifth shaft portion 45.

As shown in Figure 1, the first shaft portion 41 is provided inside the first bearing 51. As shown in Figure 2, the outer circumferential surface of the first shaft portion 41 is in contact with the inner circumferential surface of the inner race 52 of the first bearing 51.

As shown in Figure 1, the second shaft portion 42 has a larger diameter than the first shaft portion 41. As shown in Figure 2, the second shaft portion 42 has a first end face 42f and a second end face 42s. The first end face 42f is in contact with the first end face 52f of the inner race 52. The first end face 42f is not in contact with the outer race 53 of the first bearing 51. The second end face 42s is in contact with the first surface 31f.

As shown in Figure 1, the third shaft portion 43 is provided in the through hole of the rotor body 31. As shown in Figure 2, the outer circumferential surface of the third shaft portion 43 is in contact with the inner circumferential surface of the rotor body 31. As shown in Figure 1, the third shaft portion 43 has a smaller diameter than the diameter of the second shaft portion 42. As shown in Figure 2, the third shaft portion 43 has an end face 43a. The end face 43a is in contact with the first end face of the inner race 56 of the second bearing 55.

As shown in Figure 1, the fourth shaft portion 44 is provided within the second bearing 55. The outer circumferential surface of the fourth shaft portion 44 is in contact with the inner circumferential surface of the inner race 56. The fourth shaft portion 44 has a smaller diameter than the third shaft portion 43.

The fifth shaft portion 45 is provided within the through hole 72h. The through hole 72h is provided in the second plate portion 72, which will be described later. The outer circumferential surface of the fifth shaft portion 45 is not in contact with the inner circumferential surface of the second plate portion 72. The fifth shaft portion 45 has a smaller diameter than the diameter of the fourth shaft portion 44.

[First bearing, second bearing]
The first bearing 51 and the second bearing 55 rotatably support the shaft 4. The first bearing 51 is mounted on the first shaft portion 41. The second bearing 55 is mounted on the fourth shaft portion 44. The configurations of the first bearing 51 and the second bearing 55 may be the same or different.

The first bearing 51 is a radial bearing having an inner race 52 and an outer race 53, as shown in Figures 2 and 3. The radial bearing in this embodiment is a ball bearing in which balls 54 are arranged between the inner race 52 and the outer race 53. The inner circumferential surface of the inner race 52 is in contact with the outer circumferential surface of the first shaft portion 41. The outer circumferential surface of the outer race 53 is in contact with the first projection 71a, which will be described later.

The inner race 52 has a first end face 52f and a second end face 52s. The outer race 53 has a first end face 53f and a second end face 53s. The first end face 52f is in contact with the first end face 42f. The second end face 52s is not in contact with the case 7 or the adjustment member 6, which will be described later. In this embodiment, the second end face 52s is in contact with a fixing member, which is not shown. This fixing member mechanically fixes the first bearing 51 and the first shaft portion 41. An example of this fixing member is a retaining ring or a shaft nut. When a shaft nut is used as the fixing member, it is preferable to form a threaded portion on the outer circumferential surface of the first shaft portion 41. This fixing member is not required. In that case, the inner race 52 and the first shaft portion 41 are fixed by fitting them together. The first end face 53f is not in contact with the shaft 4. The second end face 53s is in contact with the adjustment member 6.

Figure 2 shows an example where the first end face 52f and the first end face 53f are not misaligned along the axial direction of the first bearing 51. Figure 3 shows an example where the first end face 52f and the first end face 53f are misaligned along the axial direction of the first bearing 51. The first end face 52f and the first end face 53f may also be misaligned along the axial direction of the first bearing 51.

The misalignment between the first end face 52f and the first end face 53f is caused by the load acting on the inner race 52 due to the weight of the shaft 4 and rotor 3, and the load acting on the inner race 52 due to the attractive force of the magnet 35 toward the stator 2. Further misalignment is caused by the load acting on the inner race 52 due to the weight of the second bearing 55, and the load acting on the inner race 52 due to the pressing force of the elastic member 8 pressing the second bearing 55 toward the first bearing 51.

The inner race 52 is subjected to loads primarily from the weight of the shaft 4 and rotor 3, and from the attractive force of the magnet 35 toward the stator 2. The inner race 52 is also subjected to at least one of the following: the weight of the second bearing 55, and the pressing force exerted by the elastic member 8 pressing the second bearing 55 toward the first bearing 51. Depending on the magnitude of these loads, the first end face 52f may shift relative to the first end face 53f. In particular, the shift of the first end face 52f is greatly influenced by the attractive force of the magnet 35. That is, the stronger the magnetic force of the magnet 35, the greater the shift of the first end face 52f.

The configuration of the second bearing 55 is the same as that of the first bearing 51. That is, as shown in Figures 2 and 3, the second bearing 55 is a radial bearing having an inner race 56 and an outer race 57. The inner circumferential surface of the inner race 56 is in contact with the outer circumferential surface of the fourth shaft portion 44. The outer circumferential surface of the outer race 57 is in contact with the inner circumferential surface of the recess 72a. The recess 72a is provided in the second plate portion 72. Each of the inner race 56 and the outer race 57 has a first end face and a second end face. The first end face of the inner race 56 is in contact with the end face 43a. The second end face of the inner race 56 is not in contact with the elastic member 8 and the case 7, which will be described later. The second end face of the inner race 56 may or may not be in contact with a fixing member similar to that of the first bearing 51. This is because the outer race 57 is pressed in the direction toward the rotor 3 by the elastic member 8. The first end face of the outer race 57 is not in contact with the rotor 3 and the shaft 4. The second end face of the outer race 57 is in contact with the elastic member 8 shown in Figure 1.

Unlike this embodiment, at least one of the first bearing 51 and the second bearing 55 may be an angular contact ball bearing.

[Elastic material]
The elastic member 8 presses the second bearing 55 toward the rotor 3. The elastic member 8 makes it easier to suppress rattle between the second protrusion 71b and the adjustment member 6. The elastic member 8 is positioned between the outer race 57 and the bottom of the recess 72a. An example of the elastic member 8 is a spring washer, a disc spring washer, a corrugated washer, or a rubber O-ring.

[case]
Case 7 houses the stator 2, rotor 3, part of the shaft 4, the first bearing 51, and the second bearing 55. Case 7 comprises a first plate portion 71, a second plate portion 72, and a peripheral wall portion 73.

In this embodiment, the peripheral wall portion 73 and the second plate portion 72 are integrally constructed. In this embodiment, the peripheral wall portion 73 and the first plate portion 71 are separate components. Unlike this embodiment, the peripheral wall portion 73 and the first plate portion 71 may be integrally constructed, while the peripheral wall portion 73 and the second plate portion 72 may be separate components. Also, unlike this embodiment, the peripheral wall portion 73, the first plate portion 71, and the second plate portion 72 may be separate components. In this embodiment, the peripheral wall portion 73 and the first plate portion 71 are fixed to each other by a fastening member 92. An example of the fastening member 92 is a screw or a bolt, similar to the fastening member 91.

The peripheral wall portion 73 surrounds the outer circumference of the stator 2 and rotor 3. A hole is provided at the end face of the peripheral wall portion 73. A fastening member 92 is provided in this hole.

The first plate portion 71 has a first flat surface 71f, a second flat surface 71s, a first protrusion 71a, a second protrusion 71b, a first through hole, a second through hole, and a third through hole.

The first plane 71f is located inside the case 7. The stator 2 is positioned on the first plane 71f. The second plane 71s is located outside the case 7. The second plane 71s is located on the opposite side from the first plane 71f.

The first projection 71a is provided between the stator 2 and the first bearing 51. The shape of the first projection 71a is, for example, cylindrical. The first projection 71a is connected to the first plane 71f. The outer circumferential surface of the first projection 71a may or may not be in contact with the inner circumferential surface of the yoke 22. The inner circumferential surface of the first projection 71a is connected to the inner circumferential surface of the second projection 71b. The inner circumferential surface of the first projection 71a is in contact with the outer circumferential surface of the outer race 53. The first projection 71a can be used for positioning the first bearing 51.

The shape of the second projection 71b is cylindrical. The outer circumferential surface of the second projection 71b is connected to the second plane 71s. The inner circumferential surface of the second projection 71b is connected to the inner circumferential surface of the first projection 71a. As shown in Figure 5, a threaded portion 711 is provided on the inner circumferential surface of the second projection 71b. An adjustment member 6 is screw-connected to the inner circumferential surface of the second projection 71b.

A portion of the first shaft portion 41 is provided in the first through-hole. A fastening member 91 is provided in the second through-hole. The second through-hole is provided in a location corresponding to the hole in the stator core 21. A fastening member 92 is provided in the third through-hole. The third through-hole is provided in a location corresponding to the hole in the peripheral wall portion 73.

The second plate portion 72 has a recess 72a in the center. A through hole 72h is provided at the bottom of the recess 72a. The fifth shaft portion 45 is provided inside the through hole 72h. The inner diameter of the through hole 72h is larger than the outer diameter of the fifth shaft portion 45. Therefore, the shaft 4 rotates without the inner circumferential surface of the through hole 72h coming into contact with the fourth shaft portion 44.

[Adjustment component]
The adjustment member 6 supports the first bearing 51. The shape of the adjustment member 6 in this embodiment is cylindrical. The inner dimensions of the adjustment member 6 in this embodiment are greater than the outer diameter of the inner race 52 and less than or equal to the inner diameter of the outer race 53. The inner dimensions refer to the diameter of the inscribed circle on the inner circumferential surface of the adjustment member 6.

The adjustment member 6 has a first end face 61f, a second end face 61s, an inner circumferential surface, and an outer circumferential surface. The first end face 61f is in direct contact with the second end face 53s. The first end face 61f is not in contact with the second end face 52s. Therefore, an increase in mechanical loss can be suppressed. This is because friction does not increase since the adjustment member 6 is not in contact with the inner race 52. The second end face 61s is not in contact with the first end face 61f and the first plate portion 71.

A threaded portion 611 is provided on the outer circumferential surface of the adjustment member 6. The outer circumferential surface of the adjustment member 6 is screw-connected to the inner circumferential surface of the second projection 71b. The pitch of the threads of the threaded portion 611 can be selected as appropriate. The smaller the pitch, the easier it is to finely adjust the gap length using the adjustment member 6 during the manufacturing process. The pitch may be, for example, 2.5 mm or less. The pitch may be further 1.5 mm or less, and especially 1.0 mm or less. The lower limit of the pitch may be, for example, 0.5 mm. That is, the pitch may be 0.5 mm or more and 2.5 mm or less, and further 0.5 mm or more and 1.5 mm or less, and especially 0.5 mm or more and 1.0 mm or less.

A tool is fitted onto the inner circumferential surface of the adjustment member 6. The tool rotates the adjustment member 6 during the manufacturing process. The inner circumferential surface of the adjustment member 6 is configured in a polygonal shape. If the inner circumferential surface of the adjustment member 6 is configured in a hexagonal shape, for example, a hexagonal wrench can be used as the tool.

The axial gap motor 1 of this embodiment offers excellent assembly precision. During the manufacturing process, rotating the adjustment member 6 relative to the second projection 71b allows the first bearing 51 to move in the axial direction of the shaft 4. Because the first end face 52f and the first end face 42f are in contact, the axial movement of the first bearing 51 allows the shaft 4 to move in the axial direction. Because the second end face 42s and the first face 31f are in contact, the axial movement of the shaft 4 allows the rotor 3 to move in the axial direction. That is, the rotor 3 can be easily moved to a position where the gap length is the design length. Since the adjustment member 6 and the second projection 71b are screw-connected, the rotor 3 will not move in the axial direction unless the adjustment member 6 is rotated. Therefore, the rotor 3 is positioned at a location where the gap length is the design length G1.

[Manufacturing method for axial gap motors]
The manufacturing method of the axial gap motor of Embodiment 1 will be described mainly with reference to Figures 6 to 8. The manufacturing method of the axial gap motor of this embodiment comprises steps A and B.
Step A involves preparing the parts for the axial gap motor.
Step B involves assembling the parts.

[Process A]
The parts prepared in step A are the parts of the axial gap motor 1 described above, with reference to Figure 1. In this embodiment, the parts include the stator 2, rotor 3, shaft 4, first bearing 51, second bearing 55, adjustment member 6, case 7, elastic member 8, fastening member 91, and fastening member 92.

[Process B]
In assembly process B, each component is fixed in its designated position. By going through process B, an axial gap motor 1 as shown in Figure 1 is manufactured. The order in which the parts are assembled is, for example, from process B1 to process B7 below.

In step B1, the second protrusion 71b of the first plate portion 71 and the adjustment member 6 are screw-connected. By rotating the adjustment member 6 relative to the second protrusion 71b, the position of the first end face 61f of the adjustment member 6 can be adjusted. The position of the first end face 61f will be described later.

In step B2, the first plate portion 71 and the stator 2 are fixed together, and the first bearing 51 is positioned. The order of the above fixing and positioning does not matter. The above fixing is performed as follows: The stator 2 is positioned on the first plane 71f of the first plate portion 71. Next, the fastening member 91 is tightened between the second through hole of the first plate portion 71 and the hole of the stator 2. The above positioning is performed as follows: The first bearing 51 is fitted into the first protrusion 71a of the first plate portion 71. Then, as shown in Figure 2, the second end face 53s of the outer race 53 of the first bearing 51 is brought into contact with the first end face 61f of the adjustment member 6.

In step B3, the first shaft portion 41 of the shaft 4 is placed inside the first bearing 51. A rotor assembly, consisting of the rotor 3 and shaft 4, is prepared in advance. In step B3, the first shaft portion 41 of the rotor assembly is placed inside the first bearing 51. In this case, step B4 is skipped and step B31 is skipped. If the rotor assembly is not prepared and the rotor 3 and shaft 4 are prepared separately, step B31 is skipped before step B4. Step B31 involves fitting the rotor 3 onto the shaft 4, which has the first shaft portion 41 placed inside the first bearing 51.

In step B4, the second bearing 55 is fitted onto the fourth shaft portion 44 of the shaft 4.

In step B5, the elastic member 8 is placed on top of the second bearing 55.

In step B6, the through hole 72h of the second plate portion 72 is fitted into the fifth shaft portion 45 of the shaft 4, and the end face of the peripheral wall portion 73 and the first plate portion 71 are brought into contact. Then, the first plate portion 71 and the peripheral wall portion 73 are fixed together with fastening members 92. The fastening members 92 are provided in the third through hole of the first plate portion 71 and the aforementioned hole in the peripheral wall portion 73.

In step B1, the position of the first end face 61f of the adjustment member 6 is set such that, after going through step B6, the gap length is greater than the design length G1 or the gap length is less than the design length G1. Figure 6 shows the state in which the adjustment member 6 is positioned so that the gap length is greater than the design length G1.

In process B7, the gap length is set to the design length G1. In process B7, steps 1 and 2 are performed in order.

Step 1 involves rotating the adjustment member 6 relative to the second projection 71b. A tool (not shown) is fitted into the adjustment member 6. The tool is rotated. As shown by the arc-shaped white arrow in Figure 6, the rotation of the tool causes the adjustment member 6 to rotate relative to the second projection 71b. As shown in Figure 2, the contact between the first end face 61f and the second end face 53s causes the rotation of the adjustment member 6 to move the first bearing 51 in the axial direction of the shaft 4. The contact between the first end face 52f and the first end face 42f causes the axial movement of the first bearing 51 to move the shaft 4 in the axial direction of the shaft 4. The contact between the first face 31f and the second end face 42s causes the axial movement of the shaft 4 to move the rotor 3 in the axial direction of the shaft 4. The axial movement of the rotor 3 changes the gap length between the end face 23a and the first end face 35f. The amount of rotation of the adjustment member 6 in Step 1 can be selected as appropriate.

The amount of rotation of the adjustment member 6 is determined based on the induced voltage value generated in the coil 25. The induced voltage value can be measured by the voltmeter 110. The induced voltage value decreases as the gap length increases and increases as the gap length decreases. The design voltage value is defined as the target value of the induced voltage value determined based on the specifications of the axial gap motor 1. The design voltage value has a certain tolerance range. The gap length based on this design voltage value is the design length G1. That is, if the measured induced voltage value satisfies the design voltage value, it can be seen that the gap length satisfies the design length G1.

Step 2 involves measuring the induced voltage. The induced voltage may be measured after the adjustment member 6 has finished rotating, or while the adjustment member 6 is rotating. The induced voltage is measured without exciting the coil 25.

Steps 1 and 2 are repeated until the measured induced voltage value meets the design voltage value.

The graphs in Figures 7 and 8 show an example where steps 1 and 2 are performed four times. The induced voltage value (V) on the left vertical axis in Figures 7 and 8 is the induced voltage value when the rotor 3 is moved to the predetermined position by step 1. The gap length on the right vertical axis in Figures 7 and 8 is the gap length when the rotor 3 is moved to the predetermined position by step 1. The number of times on the horizontal axis in Figures 7 and 8 is the number of times steps 1 and 2 are performed. Figure 7 shows an example where, starting from a position where the adjustment member 6 is set to a position where "gap length > design length G1" as shown in Figure 6, steps 1 and 2 are repeated to gradually shorten the gap length to the design length G1. Although not shown in Figure 8, it shows an example where, starting from a position where the adjustment member 6 is set to a position where "gap length < design length G1", steps 1 and 2 are repeated to gradually lengthen the gap length to the design length G1.

In Figure 7, the induced voltage value increases with each additional time Step 1 is performed. This is because the gap length is gradually decreasing. On the other hand, in Figure 8, the induced voltage value decreases with each additional time Step 1 is performed. This is because the gap length is gradually increasing. As shown in Figures 7 and 8, the induced voltage value does not meet the design voltage range when Steps 1 and 2 are performed one to three times. After performing Steps 1 and 2 for the fourth time, the induced voltage value meets the design voltage range. That is, in the examples shown in Figures 7 and 8, the gap length becomes the design length G1 after performing Steps 1 and 2 four times.

When measuring the induced voltage value while rotating the adjustment member 6, the induced voltage value does not rise or fall in steps as shown in Figure 7 or Figure 8, but rather rises or falls continuously.

Process B7 may be performed between processes B4 and B5.

In this embodiment, the manufacturing method of the axial gap motor allows the position of the rotor 3 to be adjusted by the adjustment member 6 after the parts have been assembled. Alternatively, the manufacturing method of the axial gap motor in this embodiment allows the position of the rotor 3 to be adjusted by the adjustment member 6 while the parts are being assembled. Therefore, in this embodiment, the manufacturing method of the axial gap motor allows the gap length to be set to the design length G1 by assembling the parts only once. Thus, in this embodiment, the manufacturing method of the axial gap motor in this embodiment offers excellent manufacturability for an axial gap motor 1 with excellent assembly accuracy, even without using shims.

Variant form
A modified axial gap motor will be described with reference to Figures 9 and 10. The axial gap motor in this example uses a circuit board 120, a sensor 130, a magnet 140, and a cover 160, as shown in Figure 9.

The circuit board 120 is for supplying the appropriate current size at the appropriate timing to each coil 25 when using the axial gap motor. The circuit board 120 is mounted on the second plane 71s. The shape of the circuit board 120 is annular. As shown in Figure 10, the circuit board 120 has a waveform conversion element group 121, a waveform control IC (Integrated Circuit) 122, and a phase detection circuit 123.

The waveform conversion element group 121 is connected to a power supply (not shown) and the coil 25 shown in Figure 9. The waveform conversion element group 121 converts the power supply waveform into an arbitrary drive waveform. Examples of drive waveforms are three-phase sinusoidal, square, full-wave, and half-wave waveforms. The power supply is either a DC power supply or a single-phase AC power supply. The waveform control IC 122 receives signals from external devices indicating the rotational speed of the rotor 3 and the torque of the axial gap motor 1, and controls the amplitude and frequency of the waveform of the current or voltage flowing to the coil 25. Examples of external devices are resolvers, Hall sensors, and rotary encoders. The waveform control IC 122 is connected to the waveform conversion element group 121 and the phase detection circuit 123. The phase detection circuit 123 detects the rotational position of the rotor 3 and controls the phase timing of the waveform of the current or voltage flowing to the coil 25. The phase detection circuit 123 is connected to the sensor 130.

The sensor 130 is positioned to face the magnet 140. One example of the type of sensor 130 is a Hall sensor.

The magnet 140 is attached to the outer surface of the jig 141. The jig 141 is attached to the end face of the first shaft portion 41. Therefore, when the shaft 4 rotates, the jig 141 rotates as well. The shape of the jig 141 is cylindrical. The shape of the magnet 140 is cylindrical, and the magnet 140 has alternating south poles and north poles in the circumferential direction.

The cover 160 protects the circuit board 120. The cover 160 comprises a plate portion 161 and a peripheral wall portion 162. The plate portion 161 and the peripheral wall portion 162 are integrally formed. The plate portion 161 is positioned facing the second plane 71s, sandwiching the circuit board 120. The plate portion 161 covers the circuit board 120. The shape of the plate portion 161 is annular. A through hole is provided in the center of the plate portion 161. The inner diameter of the plate portion 161 is greater than the inner diameter of the adjustment member 6. Therefore, it is easy to insert a tool into the through hole of the plate portion 161. Thus, it is easy to rotate the adjustment member 6 with a tool. The shape of the peripheral wall portion 162 is cylindrical. The peripheral wall portion 162 is provided on the outside of the outer surface of the circuit board 120. The peripheral wall portion 162 is attached to the second plane 71s.

The axial gap motor in this example, like that in Embodiment 1, exhibits excellent assembly accuracy even without the use of shims.

Embodiment 2
The axial gap motor of Embodiment 2 has a washer 65, as shown in Figure 11. The washer 65 is positioned between the second end face 53s and the first end face 61f. The inner diameter of the washer 65 is greater than the outer diameter of the inner race 52 and less than or equal to the inner diameter of the outer race 53. The washer 65 makes it easier for the adjustment member 6 to support the outer race 53. An example of the type of washer 65 is a flat washer or a disc spring washer. A flat washer improves the fit between the second end face 53s and the first end face 61f. A disc spring washer makes it easier to prevent loosening of the adjustment member 6 against the second projection 71b.

The shape of the adjustment member 6 in this embodiment is cylindrical, similar to that of Embodiment 1. The lower limit of the inner dimension of the cylindrical adjustment member 6 can be set to be greater than or equal to the inner diameter of the inner race 52 and less than or equal to the outer diameter of the inner race 52. This is because the washer 65 prevents contact between the adjustment member 6 and the inner race 52. Therefore, in this embodiment, even if the inner dimension of the adjustment member 6 is greater than or equal to the inner diameter of the inner race 52 and less than or equal to the outer diameter of the inner race 52, the increase in mechanical loss can be suppressed in the axial gap motor.

Unlike this embodiment, the shape of the adjustment member 6 can also be cylindrical. This is because the washer 65 prevents contact between the adjustment member 6, which is a solid cylindrical object, and the inner race 52. Therefore, even if the shape of the adjustment member 6 is cylindrical, the axial gap motor of this embodiment can suppress an increase in mechanical loss. The cylindrical adjustment member 6 has a first recess. The first recess is into which a tool is fitted. The first recess is provided on the second end face of the adjustment member 6. As shown in Figure 11, when the first shaft portion 41 protrudes beyond the second end face 52s, the cylindrical adjustment member 6 has a second recess. The first shaft portion 41 is positioned in the second recess. The second recess is provided on the first end face of the adjustment member 6. The inner dimensions of the second recess are such that the inner circumferential surface of the second recess does not come into contact with the outer circumferential surface of the first shaft portion 41. The inner dimensions refer to the diameter of the inscribed circle of the inner circumferential surface of the second recess. The depth of the second recess is such that the bottom of the second recess does not come into contact with the end face of the first shaft portion 41. If the end face of the first shaft portion 41 and the second end face 52s are substantially flush and the first shaft portion 41 does not come into contact with the cylindrical adjustment member 6, then the second recess is not necessary.

The present invention is not limited to these examples, but is intended to include all modifications within the meaning and scope of the claims, as shown by the claims.

For example, the yoke may be constructed by connecting multiple fan-shaped yoke pieces in a ring shape. The number of teeth connected to each yoke piece may be one or more.

Furthermore, the axial gap motor may also be a double-stator, single-rotor type axial gap motor. A double-stator, single-rotor type axial gap motor is a motor with two stators and one rotor. In a double-stator, single-rotor type axial gap motor, one rotor is assembled to be sandwiched between the two stators.

1 Axial gap motor 2 Stator 21 Stator core 22 Yoke, 22f First face, 22s Second face 23 Teeth, 23a End face 24 Coating particles, 241 Metal particles 242 Insulating coating 25 Coil 3 Rotor 31 Rotor body, 31f First face, 31s Second face 32 Recess, 32a Bottom face 35 Magnet, 35f First end face 38 Adhesive 4 Shaft 41 First shaft section 42 Second shaft section, 42f First end face, 42s Second end face 43 Third shaft section, 43a End face 44 Fourth shaft section, 45 Fifth shaft section 51 First bearing 52 Inner race, 52f First end face, 52s Second end face 53 Outer race, 53f First end face, 53s Second end face 54 Ball 55 Second bearing 56 Inner race, 57 Outer race 6 Adjustment member 61f First end face, 61s Second end face, 611 Threaded part 65 Washer 7 Case 71 First plate part, 71f First plane, 71s Second plane 71a First projection, 71b Second projection, 711 Threaded part 72 Second plate part, 72a Recess, 72h Through hole 73 Peripheral wall part 8 Elastic member 91, 92 Fastening member 110 Voltmeter 120 Circuit board 121 Waveform conversion element group, 122 Waveform control IC, 123 Phase detection circuit 130 Sensor, 140 Magnet, 141 Jig 160 Cover, 161 Plate part, 162 Peripheral wall part A, B, C Area G1 Design length

Claims (9)

Rotor and,
A stator is positioned with a gap of design length in the direction of rotation of the rotor,
The shaft which is the rotation axis of the rotor,
The first bearing rotatably supports the aforementioned shaft,
The shaft is rotatably supported, and a second bearing is positioned opposite the first bearing with the rotor in between,
A case having a first plane on which the stator is mounted,
It supports the first bearing and includes an adjustment member for adjusting the length of the gap ,
The adjustment member has a screw thread that is screw-connected to the case,
The first bearing moves in the axial direction of the shaft by the rotation of the adjusting member.
Axial gap motor. The axial gap motor according to claim 1, wherein the pitch of the screw threads of the adjustment member is 2.5 mm or less. The axial gap motor according to claim 1 or claim 2, further comprising an elastic member that presses the second bearing toward the first bearing. The first bearing is a radial bearing having an inner race and an outer race.
The axial gap motor according to claim 1 or 2, wherein the adjusting member supports the outer race without contacting the inner race. The axial gap motor according to claim 4, further comprising a washer positioned between the outer race and the adjustment member. The stator is,
A stator core having a yoke configured in the shape of an annular plate, and a plurality of teeth provided to protrude from the yoke,
Each of the plurality of teeth has a coil,
The axial gap motor according to claim 1 or claim 2, wherein the stator core is fixed to the first plane. The axial gap motor according to claim 6, wherein the stator core is made of a compacted powder molded body. The axial gap motor according to claim 1 or claim 2, wherein the number of stators and the number of rotors are one each. The process of preparing the parts for the axial gap motor,
The process includes assembling the aforementioned parts,
The aforementioned parts are,
Rotor and,
stator and,
The shaft which is the rotation axis of the rotor,
A bearing that rotatably supports the aforementioned shaft,
A case having a first plane on which the stator is mounted,
The case includes an adjustment member that supports the bearing by being screw-connected to the case,
The stator is,
A stator core having a yoke and multiple teeth,
Each of the plurality of teeth has a coil,
In the process of assembling the aforementioned parts, the adjustment member is rotated relative to the case, causing the shaft to be raised and lowered via the bearing, thereby setting the length of the gap between the rotor and the stator to the design length.
The amount of rotation of the adjustment member is determined based on the induced voltage value generated in the coil.
A method for manufacturing an axial gap motor.