Axial flux motor and rotary machine

Abstract

To provide an axial gap type motor capable of reducing magnetic attraction force while maintaining desired torque.SOLUTION: The axial gap type motor includes a rotor 1 provided with a permanent magnet 5, and a stator 6 opposed to the rotor 1 with a gap in the direction in which the rotary shaft of the rotor 1 extends. The stator 6 includes a stator core 6A provided with a plurality of teeth 6Aa and a stator coil 6B wound around each of the teeth 6Aa, and a relationship of 0.2 <θ t / θ s <0.8 is satisfied between a tooth width angle θ t indicating a center-to-center distance between the teeth 6Aa and a slot angle θ s indicating a center-to-center distance between the adjacent teeth 6Aa.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an axial gap motor in which a rotor and a stator are arranged with a small gap in the direction in which the rotation axis of the rotor extends (axial direction), and further to a rotating machine equipped with such an axial gap motor. [Background technology]

[0002] Recently, axial gap motors have been attracting attention due to their thin design and high torque density. An axial gap motor has a rotor equipped with a permanent magnet and a stator that faces the rotor with a small gap (also called an air gap) in the direction of the rotor's rotation axis. Such axial gap motors are also called axial flux motors.

[0003] Axial gap motors have the advantage of being able to easily generate the desired torque without taking up much space, and so rotating machines equipped with axial gap motors (see, for example, Patent Document 1) have come into widespread use. Examples of rotating machines equipped with axial gap motors include fan devices, pump devices, blower devices, and compressor devices. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-13040 A Summary of the Invention [Problem to be solved by the invention]

[0005] When a strong magnetic attraction force is generated between the stator and rotor during operation of an axial gap motor, this magnetic attraction force acts on the components of the rotating machine, such as bearings, causing damage to these components and shortening their lifespan. In particular, if the bearings are sliding bearings, there is a risk that the bearings will not be able to support the magnetic attraction force, and the strong magnetic attraction force may also cause vibration and noise from the rotating machine.

[0006] To address this issue, various measures have been considered to reduce the magnetic attraction force between the stator and rotor, such as selecting permanent magnets with low residual magnetic flux density or reducing the volume of the permanent magnets. However, these measures reduce not only the magnetic attraction force but also the torque, which could result in the rotating machine being unable to generate the desired torque.

[0007] Therefore, an object of the present invention is to provide an axial gap motor that can reduce the magnetic attractive force while maintaining a desired torque, and to provide a rotating machine equipped with such an axial gap motor. [Means for solving the problem]

[0008] In one aspect, an axial gap motor is provided, comprising: a rotor provided with a permanent magnet; and a stator facing the rotor with a gap in the direction of extension of the rotor's rotation axis, wherein the stator comprises a stator core provided with a plurality of teeth and a stator coil wound around each of the plurality of teeth, and wherein a tooth width angle θt indicating the center-to-center width of each tooth and a slot angle θs indicating the center-to-center distance between adjacent teeth satisfy the relationship 0.2<θt / θs<0.8.

[0009] In one embodiment, the circumferential length of the inner circumferential edge of the tooth is shorter than the circumferential length of the outer circumferential edge of the tooth. In one embodiment, the teeth have flanges formed at their tips, and the face width angle θt corresponds to the center-to-center distance of the flanges. In one embodiment, the relationship between the face width angle θt and the slot angle θs is 0.25<θt / θs<0.6. In one embodiment, the relationship between the width angle θt and the slot angle θs is 0.25<θt / θs<0.4.

[0010] In one aspect, there is provided a rotary machine comprising a main shaft, a bearing that rotatably supports the main shaft, and an axial gap motor that rotates the main shaft, wherein the axial gap motor is the axial gap motor described above.

[0011] In one embodiment, the bearing is a plain bearing. [Effects of the Invention]

[0012] According to the above-described embodiment, the spacing between adjacent teeth is set so that the value of θt / θs, which indicates the relationship between the tooth width angle θt and the slot angle θs, is between 0.2 and 0.8. This results in a significantly smaller tooth cross-sectional area than that of conventional axial gap motors. As a result, the magnetic attraction force acting between the stator and rotor can be significantly reduced. Meanwhile, the desired torque can be maintained by appropriately adjusting or selecting the amount of winding and / or the type and thickness of the winding of the stator coil. Furthermore, the manufacturing cost of the pump device can be reduced depending on the tooth cross-sectional area. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view showing a rotary machine according to one embodiment. [Figure 2] FIG. 2 is a diagram showing a bearing assembly. [Figure 3] FIG. 3 is a top view schematically showing a stator core according to one embodiment. [Figure 4] FIG. 4 is a graph showing the results of a simulation showing the relationship between the torque generated in the rotor and the value of θt / θs. [Figure 5]FIG. 5 is a graph showing the simulation results showing the relationship between the magnetic attractive force generated between the rotor and the stator and the value of θt / θs when a simulation is performed under the same conditions as the simulation shown in FIG. [Figure 6] FIG. 6 is a graph showing the relationship between the torque shown in FIG. 4 and the magnetic attraction force shown in FIG. [Figure 7] FIG. 7 is a top view that schematically shows an example of a stator core when the value of θt / θs is 0.2. [Figure 8] FIG. 8 is a top view schematically showing another example of a stator core when the value of θt / θs is 0.8. [Figure 9] FIG. 9(a) is a top view showing a stator core according to another embodiment, and FIG. 9(b) is a cross-sectional view schematically showing teeth of the stator core shown in FIG. 9(a). DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Fig. 1 is a cross-sectional view showing a rotary machine according to one embodiment. The rotary machine shown in Fig. 1 is a pump device with an integrated motor and pump. Note that, although an example in which the rotary machine is a pump device will be described below, the rotary machine is not limited to this example. The rotary machine may be, for example, a fan device, a blower device, a compressor device, or the like.

[0015] The pump device shown in Fig. 1 includes a motor pump in which a motor and a pump are integrated. The motor pump shown in Fig. 1 is a canned motor pump equipped with an axial gap motor (more specifically, an axial gap PM motor). As shown in Fig. 1, the motor pump includes an impeller 1 in which a plurality of permanent magnets 5 are embedded, a stator 6 that generates a magnetic force acting on these permanent magnets 5, a pump casing 2 that houses the impeller 1, a motor casing 3 that houses the stator 6, and a bearing assembly 10 that supports the radial load and thrust load of the impeller 1. In this embodiment, the impeller 1 in which the permanent magnets 5 are embedded functions as the rotor of the axial gap motor.

[0016] The stator 6 and the bearing assembly 10 are disposed on the suction side of the impeller 1. In this embodiment, a plurality of permanent magnets 5 are provided, but the configuration of the permanent magnets 5 is not limited to the example of this embodiment. For example, the motor pump may have a single permanent magnet with multiple magnetized poles. More specifically, the motor pump may have a single annular permanent magnet with multiple magnetic poles, with south poles and north poles magnetized alternately.

[0017] An O-ring 9 is provided as a sealing member between the pump casing 2 and the motor casing 3. By providing the O-ring 9, it is possible to prevent liquid from leaking between the pump casing 2 and the motor casing 3.

[0018] A suction port 15 having a suction port 15a is connected to the motor casing 3. This suction port 15 has a flange shape and is connected to a suction line (not shown). Liquid flow paths 15b, 3a, and 10a are formed in the center of the suction port 15, motor casing 3, and bearing assembly 10, respectively. These liquid flow paths 15b, 3a, and 10a are connected in a line to form a single liquid flow path extending from the suction port 15a to the liquid inlet of the impeller 1. The liquid flow paths 15b, 3a, and 10a are connected to the liquid inlet of the impeller 1.

[0019] The motor pump according to this embodiment is a canned motor pump equipped with an axial gap type motor in which the permanent magnet 5 and the stator 6 are arranged along these liquid flow paths 15b, 3a, and 10a.

[0020] A discharge port 16 having a discharge port 16a is provided on the side of the pump casing 2, and the liquid pressurized by the rotating impeller 1 is discharged through the discharge port 16a. The motor pump according to this embodiment is a so-called end-top type motor pump, in which the suction port 15a and the discharge port 16a intersect at right angles.

[0021] The impeller 1 is made of a non-magnetic material that is slippery and resistant to wear. Suitable non-magnetic materials include resins such as PTFE (polytetrafluoroethylene) and PPS (polyphenylene sulfide), and ceramics. The pump casing 2 and motor casing 3 can also be made of the same material as the impeller 1.

[0022] 2 is a diagram showing a bearing assembly 10. The impeller 1 is rotatably supported by a single bearing assembly 10. This bearing assembly 10 is a sliding bearing (hydrodynamic bearing) that uses the dynamic pressure of a liquid. This bearing assembly 10 includes a fixed-side bearing 12, a rotating-side bearing 11 that is arranged around the fixed-side bearing 12, and an intermediate bearing 17 that is rotatably arranged between the fixed-side bearing 12 and the rotating-side bearing 11.

[0023] The fixed-side bearing 12 has a cylindrical fixed-side radial surface 12a and a fixed-side thrust surface 12b located radially outward of the fixed-side radial surface 12a. The rotating-side bearing 11 has a cylindrical rotating-side radial surface 11a surrounding the fixed-side radial surface 12a and a rotating-side thrust surface 11b located radially outward of the rotating-side radial surface 11a. The rotating-side bearing 11 is arranged to surround the fixed-side bearing 12. The intermediate bearing 17 is arranged between the rotating-side thrust surface 11b of the rotating-side bearing 11 and the fixed-side thrust surface 12b of the fixed-side bearing 12.

[0024] The rotating-side bearing 11 is fixed to the impeller 1 and is arranged to surround the liquid inlet of the impeller 1. The fixed-side bearing 12 is fixed to the motor casing 3 and is arranged on the suction side of the rotating-side bearing 11.

[0025] The rotating-side radial surface 11a and the fixed-side radial surface 12a are radial surfaces that support the radial load of the impeller 1, and the rotating-side thrust surface 11b and the fixed-side thrust surface 12b are thrust surfaces that support the thrust load of the impeller 1. The rotating-side radial surface 11a and the fixed-side radial surface 12a are parallel to the axis of the impeller 1, and the rotating-side thrust surface 11b and the fixed-side thrust surface 12b are perpendicular to the axis of the impeller 1. The rotating-side radial surface 11a and the rotating-side thrust surface 11b are perpendicular to each other, and the fixed-side radial surface 12a and the fixed-side thrust surface 12b are perpendicular to each other. The shapes of the rotating-side bearing 11 and the fixed-side bearing 12 are not limited to the example in FIG. 2, and the rotating-side bearing 11 and the fixed-side bearing 12 may have tapered surfaces.

[0026] 2, the bearing assembly 10 further includes a stopper 19 having a stopper end face 19b that protrudes outward from the fixed-side radial surface 12a. The stopper 19 is disposed between the rotating-side thrust surface 11b and the fixed-side thrust surface 12b. The fixed-side radial surface 12a and the fixed-side thrust surface 12b are connected to each other via the stopper 19.

[0027] The stopper 19 may have an annular shape or may be made up of a plurality of members arranged at equal intervals along the circumferential direction of the fixed-side radial surface 12 a. In this embodiment, the stopper 19 is integrally formed with the fixed-side bearing 12.

[0028] Intermediate bearing 17 has an annular shape and has a first bearing end face 17a that contacts fixed-side thrust surface 12b of fixed-side bearing 12, a second bearing end face 17b that contacts rotating-side thrust surface 11b of rotating-side bearing 11, and an inner surface 17c that connects first bearing end face 17a and second bearing end face 17b. Rotating-side bearing 11, fixed-side bearing 12, and intermediate bearing 17 are arranged concentrically with one another.

[0029] The intermediate bearing 17 is disposed around the stopper 19. More specifically, the inner surface 17c of the intermediate bearing 17 faces the outer surface 19a of the stopper 19. The stopper 19 is located between the rotating-side thrust surface 11b of the rotating-side bearing 11, the fixed-side thrust surface 12b of the fixed-side bearing 12, and the inner surface 17c of the intermediate bearing 17. However, the positional relationship between the intermediate bearing 17 and the stopper 19 is not limited to this embodiment. In one embodiment, the stopper 19 may be disposed outside the intermediate bearing 17 in the direction perpendicular to the axis of the impeller 1. In other words, the intermediate bearing 17 may be disposed toward the center of the fixed-side bearing 12, and the stopper 19 may be disposed outside the intermediate bearing 17.

[0030] 2, a first axial gap G1 is formed between the rotating-side bearing 11 and the stopper 19, and a second axial gap G2 is formed between the impeller 1 and the motor casing 3, with the first axial gap G1 being smaller than the second axial gap G2. Hereinafter, the first axial gap G1 may be simply referred to as the first gap G1, and the second axial gap G2 may be simply referred to as the second gap G2. In this specification, the term "axial direction" refers to a direction parallel to the direction in which the rotation axis of the impeller 1, which is rotatably supported by the bearing assembly 10, extends.

[0031] The impeller 1 and the motor casing 3 face each other via a second gap G2, and the impeller 1 rotates when the rotating magnetic field generated by the stator 6 acts on the permanent magnets 5. It is preferable that the second gap G2 between the impeller 1 and the motor casing 3 is as small as possible without causing them to come into contact with each other.

[0032] A portion of the liquid discharged from the impeller 1 is guided to the bearing assembly 10 through a small gap G2 between the impeller 1 and the motor casing 3. When the rotating-side bearing 11 rotates together with the impeller 1, dynamic pressure of the liquid is generated between the rotating-side bearing 11 and the intermediate bearing 17 and / or between the intermediate bearing 17 and the fixed-side bearing 12, and as a result, the impeller 1 is supported by the bearing assembly 10 without contact. With this configuration, tilting of the impeller 1 is restricted by the bearing assembly 10.

[0033] As shown in Figure 1, the pump device further includes an inverter device 26 that supplies current to the stator 6. The stator 6 has a stator core 6A provided with a plurality of teeth 6Aa and a plurality of stator coils 6B wound around each of the teeth 6Aa. The plurality of teeth 6Aa and the stator coils 6B are arranged in an annular shape. The impeller 1 and the stator 6 are arranged concentrically with the bearing assembly 10 and the suction port 15a.

[0034] The stator coil 6B is connected to an inverter device 26 via lead wires 25. This inverter device 26 supplies current to the stator coil 6B of the stator 6, causing the stator 6 to generate a rotating magnetic field. This rotating magnetic field acts on the permanent magnets 5 embedded in the impeller 1, driving the impeller 1 to rotate. The torque of the impeller 1 depends on the magnitude of the current supplied to the stator 6. As long as the load on the impeller 1 is constant, the current supplied to the stator 6 is approximately constant while the impeller 1 is rotating at a predetermined speed.

[0035] As the impeller 1 rotates, liquid is introduced into the liquid inlet of the impeller 1 from the suction port 15a. The liquid is pressurized by the rotation of the impeller 1 and is discharged from the discharge port 16a. While the impeller 1 is transporting the liquid, the back surface of the impeller 1 is pressed against the suction side (i.e., toward the suction port 15a) by the pressurized liquid. The bearing assembly 10 is disposed on the suction side of the impeller 1, and therefore supports the thrust load of the impeller 1 from the suction side.

[0036] In order for the pump device to achieve the desired performance, the impeller 1, which functions as the rotor of the axial gap motor, needs to be rotated with the desired torque. However, if a strong magnetic attraction force is generated between the stator 6 and the impeller 1, the magnetic attraction force may act on the components of the pump device, such as the bearing assembly 10, which is a sliding bearing, and may cause damage to the components of the pump device or shorten their lifespan. Furthermore, in this embodiment, because the bearing assembly 10 is a sliding bearing, there is a risk that the magnetic attraction force may not be supported by the bearing assembly 10. In addition, the strong magnetic attraction force may cause vibration and noise to be generated from the pump device.

[0037] Therefore, the inventors have found a new and original configuration for the stator 6 that can reduce the magnetic attractive force while maintaining the desired torque required by the pump device, and have completed the present invention. The detailed configuration of the stator 6 will be described below.

[0038] Fig. 3 is a top view schematically showing a stator core according to one embodiment. The stator core 6A shown in Fig. 3 has six teeth 6Aa. Note that Fig. 3 does not show the stator coils 6B wound around each tooth 6Aa, and only the stator core 6A of the stator 6 is depicted. In the stator core 6A shown in Fig. 3, the teeth 6Aa have the same shape and are arranged at equal intervals in the circumferential direction of the stator core 6A.

[0039] In this embodiment, the stator core 6A of the stator 6 is formed so that the relationship between the face width angle θt, which indicates the center-to-center width of each tooth 6Aa, and the slot angle θs, which indicates the center-to-center distance between adjacent teeth 6A, satisfies 0.2<θt / θs<0.8. Here, in this embodiment, the face width angle θt is defined as the angle between points 6Aa1 and 6Aa2 at which an imaginary circle VC (see the dashed-dotted line in FIG. 3 ), which is centered on the axis CP1 of the stator core 6A and passes through the center CP2 of the tooth 6Aa, contacts the side of the tooth 6Aa. Furthermore, the slot angle θs is defined as the angle between the contact points 6Aa1 and 6Aa2 of adjacent teeth 6Aa.

[0040] The center CP2 of the tooth 6Aa is the center between the inner peripheral edge 6Aa3 and the outer peripheral edge 6Aa4 of the tooth 6Aa, as viewed in the radial direction of the stator core 6A. In other words, as viewed in the radial direction of the stator core 6A, the distance from the inner peripheral edge 6Aa3 of the tooth 6Aa to the center CP2 is equal to the distance from the center CP2 to the outer peripheral edge 6Aa4 of the tooth 6Aa. Furthermore, as viewed in the radial direction of the stator core 6A, the distance from a contact point 6Aa1 located on the imaginary circle VC to the inner peripheral edge 6Aa3 is equal to the distance from the contact point 6Aa1 to the outer peripheral edge 6Aa4, and the distance from a contact point 6Aa2 located on the imaginary circle VC to the inner peripheral edge 6Aa3 is equal to the distance from the contact point 6Aa2 to the outer peripheral edge 6Aa4.

[0041] FIG. 4 is a graph showing the simulation results of the relationship between the torque generated in the rotor and θt / θs, and FIG. 5 is a graph showing the simulation results of the relationship between the magnetic attractive force generated between the rotor and the stator and θt / θs when simulated under the same conditions as the simulation shown in FIG. 4. FIG. 6 is a graph showing the relationship between the torque shown in FIG. 4 and the magnetic attractive force shown in FIG. 5. In the graph shown in FIG. 4, the vertical axis represents torque, and the horizontal axis represents the value of θt / θs. In the graph shown in FIG. 5, the vertical axis represents magnetic attractive force, and the horizontal axis represents the value of θt / θs. In the graph shown in FIG. 6, the vertical axis represents torque, and the horizontal axis represents magnetic attractive force.

[0042] In this simulation, the desired torque required of the impeller 1 (the rotor) to achieve the desired performance of the pump device was set to approximately 2.2 Nm (see dotted line TL in FIG. 4). Furthermore, the lower limit of the torque that is expected to achieve the desired torque by appropriately adjusting or selecting the amount of winding and / or the type and thickness of the winding of the stator coil 6B is approximately 1.9 Nm (see dotted line LL in FIG. 4).

[0043] As is clear from FIG. 4, when the value of θt / θs is between 0.2 and 0.8, the desired torque required of the impeller 1 for the pump device to exhibit the desired performance can be generated. On the other hand, as shown in FIG. 5, when the value of θt / θs is less than 0.2, the magnetic attractive force increases rapidly as the value of θt / θs increases (see the slope of the approximate line SL1 in FIG. 5). However, when the value of θt / θs is 0.2 or greater, the rate of increase in the magnetic attractive force with an increase in the value of θt / θs decreases significantly compared to when the value of θt / θs is less than 0.2 (see the slope of the approximate line SL2 in FIG. 5). Note that, from the perspective of the efficiency of the axial gap motor, it is not preferable to manufacture the stator core 6A so that the value of θt / θs is less than 0.2. Therefore, by manufacturing the stator core 6A so that the value of θt / θs in the stator core 6A is in the range of 0.2 to 0.8, it is possible to suppress the increase in the magnetic attractive force while maintaining the desired torque.

[0044] Fig. 7 is a top view schematically showing an example of a stator core when the value of θt / θs is 0.2, and Fig. 8 is a top view schematically showing another example of a stator core when the value of θt / θs is 0.8. Note that θt / θs of the stator core 6A shown in Fig. 3 is set to 0.26.

[0045] In axial gap motors, magnetic flux can generally be effectively utilized by increasing the surface area of ​​the permanent magnet and the cross-sectional area of ​​the stator core teeth. Therefore, conventional axial gap motors have not been designed with large spacing between adjacent teeth, as shown in FIGS. 3, 7, and 8. In other words, since torque acting on the rotor is more easily generated when the surface area of ​​the permanent magnet and the cross-sectional area of ​​the stator core teeth are large than when they are small, axial gap motor designs typically attempt to increase the cross-sectional area of ​​the stator core teeth. In other words, those skilled in the art of axial gap motors do not envision a stator as shown in FIGS. 3, 7, and 8. Rather, if the stator core 6Aa shown in FIGS. 3, 7, and 8 exists, they typically attempt to add additional teeth between adjacent teeth 6Aa or increase the cross-sectional area of ​​each tooth 6Aa.

[0046] As a result of extensive research into the structure of the stator core, the inventors arrived at the configuration of this embodiment, which allows for a reduction in the magnetic attractive force generated between the rotor and the stator while maintaining the desired torque required of the rotor by increasing the spacing between adjacent teeth so that the value of θt / θs is between 0.2 and 0.8. The configuration of this embodiment of the stator core 6A is a new and innovative idea that breaks the conventional wisdom of stator design.

[0047] As described above, the torque of the impeller 1 depends on the magnitude of the current supplied to the stator 6. Therefore, even if the slot angle θs is increased (or the tooth width angle θt is reduced) as in the stator core 6A shown in FIGS. 3, 7, and 8, the desired torque required by the rotary machine can be maintained by increasing the current supplied to the stator coil 6B (see FIG. 1). Instead of or in addition to increasing the current supplied to the stator coil 6B, the torque generated in the rotor of the rotary machine can be adjusted by changing the type and thickness of the winding of the stator coil 6B, or by increasing or decreasing the amount of winding. In this embodiment, the stator coil 6B wound around the teeth 6Aa can have a maximum winding amount of approximately half the slot angle θs on one side.

[0048] Furthermore, the simulation results shown in FIG. 6 show that the relationship between torque and magnetic attractive force forms an upward convex curve. In other words, it was found that there is an upper limit to the torque acting on the rotor, regardless of the magnitude of the magnetic attractive force. Here, from FIG. 6, the magnetic attractive force is 150 N when the desired torque of 2.2 Nm is exerted on the impeller 1 (the rotor). From FIG. 5, it can be seen that the value of θt / θs when the magnetic attractive force is 150 N is approximately 0.6. From FIG. 4, it can be seen that when the value of θt / θs is 0.6, the impeller 1 can rotate while fully exerting the desired torque. Furthermore, from FIG. 4, it can be seen that when the value of θt / θs is less than 0.25, the torque generated in the impeller 1 becomes lower than the desired torque. Therefore, it is more preferable to form the stator core 6A of the stator 6 so that the relationship between the face width angle θt and the slot angle θs satisfies 0.25<θt / θs<0.6.

[0049] Furthermore, Fig. 6 shows that the torque generated in the impeller 1 (rotor) is maximum when the magnetic attractive force is 125 N, and Fig. 5 shows that the value of θt / θs is 0.4 when the magnetic attractive force is 125 N. Fig. 4 shows that when the value of θt / θs is 0.4, the impeller 1 can rotate while fully exerting the desired torque. Therefore, it is most preferable to manufacture the stator core 6A so that the value of θt / θs is in the range of 0.25 to 0.4.

[0050] As shown in Figures 3, 7, and 8, the circumferential length (arc size) of the inner peripheral edge 6Aa3 of each tooth 6Aa is shorter than the circumferential length (arc size) of the outer peripheral edge 6Aa4 of each tooth 6Aa.

[0051] With this configuration, the magnetic attraction force acting between the stator 6B and the impeller 1 can be significantly reduced simply by significantly reducing the cross-sectional area of ​​the teeth 6Aa in the direction perpendicular to the rotation axis of the impeller 1, which functions as a rotor. Furthermore, the torque required for the pump device can be generated by adjusting the manufacturing conditions of the stator coil 6B. Furthermore, since the size of the permanent magnet 5 can be reduced according to the cross-sectional area of ​​the teeth 6Aa, the manufacturing cost of the pump device can also be reduced.

[0052] Fig. 9(a) is a top view showing a stator core according to another embodiment, and Fig. 9(b) is a cross-sectional view showing a schematic view of the teeth of the stator core shown in Fig. 9(a). The configuration of this embodiment that is not particularly described is the same as the above-described embodiment, and therefore, redundant description thereof will be omitted.

[0053] As shown in FIGS. 9(a) and 9(b), each tooth 6Aa of the stator core 6A may have a flange 6Aa6 at its tip. More specifically, the tooth 6Aa of the stator core 6A shown in FIGS. 9(a) and 9(b) includes a tooth body 6Aa5 and a flange 6Aa6 formed at the tip of the tooth body 6Aa5. In this embodiment, the flange 6Aa6 of the tooth 6Aa is formed integrally with the tooth body 6Aa5. The stator coil 6B is wound around the tooth body 6Aa5, and the flange 6Aa6 prevents the stator coil 6B from falling off the stator core 6A.

[0054] 9(a), when a tooth 6Aa of a stator core 6A has a flange 6Aa6, points 6Aa1 and 6Aa2 at which an imaginary circle VC centered on the axis CP1 of the stator core 6A and passing through the center CP2 of the tooth 6Aa contacts the side surface of the tooth 6Aa are provided on the side surface of the flange 6Aa6. In other words, a tooth width angle θt indicating the center-to-center width of each tooth 6Aa is the angle between the contact points 6Aa1 and 6Aa2 provided on the side surface of the flange 6Aa6, and a slot angle θs indicating the center-to-center distance of adjacent teeth 6Aa is the angle between the contact points 6Aa1 and 6Aa2 provided on the side surface of the flange 6Aa6 of adjacent teeth 6Aa.

[0055] With this configuration, the amount of winding that can be wound around the stator coil 6B can be increased, thereby effectively increasing the torque generated in the impeller 1 while reducing the magnetic attraction force between the impeller 1, which functions as a rotor, and the stator 6.

[0056] The above-described embodiment is an axial gap motor of the so-called "one stator, one rotor type" that includes one stator 6A and one rotor 1. However, the above-described embodiment may also be applied to the stator of an axial gap motor of the so-called "one stator, two rotor type" that includes one stator and two rotors, or to the stator of an axial gap motor of the so-called "two stator, one rotor type" that includes two stators and one rotor.

[0057] Furthermore, in the above-described embodiment, the stator core 6A has six teeth 6Aa, but the number of teeth 6Aa is not limited to 6. The number of teeth 6Aa may be more or less than 6 as long as the value of θt / θs is in the range of 0.25 to 0.8.

[0058] The above-described embodiments have been described for the purpose of enabling a person of ordinary skill in the art to practice the present invention. Various modifications of the above-described embodiments would be obvious to a person skilled in the art, and the technical concept of the present invention may be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is to be interpreted in the broadest scope in accordance with the technical concept defined by the claims. [Explanation of symbols]

[0059] 1 Impeller (rotor) 2 Pump casing 3 Motor casing 5. Permanent magnets 6 Stator 6A stator core 6Aa tooth 6Aa1 contact 6Aa2 contact 6Aa3 Inner edge 6Aa4 outer edge 6Aa5 Tooth body 6Aa6 Tsuba 6B stator coil 10 Bearing assembly 11 Rotating side bearing 15 Suction port 16 Discharge port 17 Intermediate bearing 19 Stopper 26 Inverter device

Claims

1. a rotor provided with a permanent magnet; a stator facing the rotor with a gap in a direction in which the rotation axis of the rotor extends, The stator includes: a stator core provided with a plurality of teeth; a stator coil wound around each of the plurality of teeth, An axial gap motor in which the relationship 0.2<θt / θs<0.8 holds between the tooth width angle θt, which indicates the center-to-center width of each tooth, and the slot angle θs, which indicates the center-to-center distance of adjacent teeth.

2. 2. The axial gap motor according to claim 1, wherein the circumferential length of the inner circumferential edge of the tooth is shorter than the circumferential length of the outer circumferential edge of the tooth.

3. The teeth have flanges formed at their tips, 2. The axial gap motor according to claim 1, wherein the tooth width angle θt corresponds to a distance between centers of the flanges.

4. 4. The axial gap motor according to claim 1, wherein the tooth width angle θt and the slot angle θs satisfy the relationship 0.25<θt / θs<0.

6.

5. 5. The axial gap motor according to claim 4, wherein the relationship between the tooth width angle θt and the slot angle θs is 0.25<θt / θs<0.

4.

6. The main axis and a bearing that rotatably supports the main shaft; an axial gap type motor that rotates the main shaft, The rotary machine, wherein the axial gap motor is the axial gap motor according to claim 1 .

7. The rotary machine according to claim 6 , wherein the bearing is a plain bearing.

Images