Motors and washing machines

Abstract

To provide a slim axial gap motor a magnetic characteristic of which can be easily adjusted, and a washing machine having the motor.SOLUTION: A motor includes a rotor and a stator. The rotor rotates about a center axis. The stator faces the rotor with a gap disposed therebetween in an axial direction of the center axis. The rotor has a plurality of magnets. The plurality of magnets are arranged in the circumferential direction, and each have a magnetic pole direction in the axial direction. The stator has a back yoke, a plurality of coils, and a core part. The back yoke extends along a plane that is orthogonal to the axial direction. The plurality of coils are arranged in the circumferential direction in the back yoke, and face the magnets in the axial direction so as to form magnetic poles. The core part is positioned, in the back yoke, on an inner diameter side of the coil, and is formed of a magnetic material in which magnetism circulation is caused with the back yoke.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a motor and a washing machine. [Background technology]

[0002] Conventionally, development of washing machines that employ an axial gap type motor to reduce the overall thickness has been progressing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-011086 Summary of the Invention [Problem to be solved by the invention]

[0004] The problem to be solved by the present invention is to provide a thin axial gap motor whose magnetic characteristics can be easily adjusted, and a washing machine having such a motor. [Means for solving the problem]

[0005] The motor of the embodiment has a rotor and a stator. The rotor rotates about a central axis. The stator faces the rotor with a gap in the axial direction of the central axis. The rotor has multiple magnets and a rotor holder. The multiple magnets are arranged circumferentially, with the axial direction being the magnetic pole direction. The rotor holder has a first opposing surface facing the stator and holds the multiple magnets. The stator has a back yoke, multiple coils, a core, and a stator holder. The back yoke is aligned along a plane perpendicular to the axial direction. The multiple coils are arranged circumferentially on the back yoke and face the magnets in the axial direction to form magnetic poles. The core is located on the inner diameter side of the coils on the back yoke and is made of a magnetic material that magnetically circulates with the back yoke. The stator holder has a second opposing surface facing the rotor and holds the multiple coils. The multiple magnets are held by the rotor holder flush with the first opposing surface. The multiple coils are held by the stator holder flush with the second opposing surface. The rotor is disposed outside the water receiving tub in a washing machine that includes a spinning tub and a water receiving tub that houses the spinning tub. The stator holder is an insert-molded body that embeds part of the bottom of the water receiving tub. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a schematic cross-sectional view of a washing machine having a motor according to an embodiment; [Figure 2] FIG. 1 is a schematic cross-sectional view of a motor according to an embodiment. [Figure 3] FIG. 2 is a cross-sectional view of the rotor taken along a plane perpendicular to the central axis. [Figure 4] 1 is a cross-sectional schematic view of a motor according to a first embodiment taken along a plane including a central axis line. [Figure 5] FIG. 3 is a cross-sectional view of the stator taken along a plane perpendicular to the central axis. [Figure 6] FIG. 10 is a diagram showing the relationship between radial position and magnetic distribution. [Figure 7] FIG. 4 is a cross-sectional schematic view of a motor according to a second embodiment taken along a plane including a central axis line. [Figure 8] FIG. 10 is a diagram showing the relationship between radial position and magnetic distribution in the second embodiment. [Figure 9] FIG. 10 is a cross-sectional schematic view of a motor according to a third embodiment taken along a plane including a central axis line. [Figure 10]FIG. 11 is a diagram showing the relationship between radial position and magnetic distribution in the third embodiment. [Figure 11] FIG. 11 is a diagram showing the relationship between radial position and magnetic distribution in the third embodiment. [Figure 12] FIG. 10 is a cross-sectional schematic view of a motor according to a fourth embodiment taken along a plane including a central axis line. [Figure 13] FIG. 11 is a diagram showing the relationship between radial position and magnetic distribution in the fourth embodiment. [Figure 14] FIG. 10 is a cross-sectional schematic view of a motor according to a fifth embodiment taken along a plane including a central axis line. [Figure 15] FIG. 13 is a diagram showing the relationship between radial position and magnetic distribution in the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, a motor and a washing machine according to an embodiment will be described with reference to the drawings. In the following description, components having the same or similar functions will be denoted by the same reference numerals. Duplicate descriptions of those components may be omitted.

[0008] The configuration of the washing machine will be described below. FIG. 1 is a cross-sectional view of a washing machine having a motor according to this embodiment. In the following description, the side of the installation surface of the washing machine, i.e., the vertically lower side, is referred to as the lower side of the washing machine, and the opposite side of the installation surface, i.e., the vertically upper side, is referred to as the upper side of the washing machine. Furthermore, left and right are defined based on the direction in which the washing machine is viewed from a user standing in front of the washing machine. Furthermore, the side closer to the user standing in front of the washing machine as viewed from the washing machine is defined as the "front," and the side further away is defined as the "rear." In this specification, the "width direction" refers to the left-right direction defined above. In this specification, the "depth direction" refers to the front-to-back direction defined above. In the drawings, the +X direction is the right direction, the -X direction is the left direction, the +Y direction is the rear direction, the -Y direction is the front direction, the +Z direction is the up direction, and the -Z direction is the down direction.

[0009] In the following description, the axial direction of the central axis J will be simply referred to as the "axial direction." In this embodiment, the central axis J is disposed so as to tilt downward from the front to the rear. Of the two sides of the axial direction, the direction facing forward and diagonally upward may be referred to as the "one axial side D1," and the direction facing rearward and diagonally downward may be referred to as the "other axial side D2." Furthermore, the radial direction centered on the central axis J may be simply referred to as the "radial direction." Furthermore, the circumferential direction centered on the central axis J may be simply referred to as the "circumferential direction."

[0010] The washing machine 1 has a housing 2, a door 2a, a water receiving tub 3, a drum (rotating tub) 4, a motor 10, a water injection pipe 5, and a drain pipe 6. The washing machine 1 of this embodiment is a drum type washing machine.

[0011] The housing 2 is made of, for example, steel plate and has an overall rectangular box shape. The housing 2 houses a water receiving tub 3, a drum 4, a motor 10, a water inlet pipe 5, and a drain pipe 6. The housing 2 forms the exterior of the washing machine 1. An entrance 2b is provided in a side wall panel located in the front of the housing 2. A door 2a is attached to the entrance 2b. The door 2a covers the entrance 2b.

[0012] The door 2a can be operated from the front by a user to either a closed state or an open state. When the door 2a is in the closed state, the entrance 2b is closed. When the door 2a is in the open state, the entrance 2b is open.

[0013] Water receiving tub 3 is fixed to the inner surface of housing 2 via a suspension or the like. Water receiving tub 3 is cylindrical and disposed about central axis J. Water receiving tub 3 is disposed in an inclined state, descending from the front to the rear.

[0014] The water receiving tub 3 has a cylindrical portion 3d centered on the central axis J, and a bottom portion 3e that covers an opening on the other axial side D2 of the cylindrical portion 3d. In other words, the water receiving tub 3 is a bottomed cylinder that opens on one axial side D1. A drum 4 is housed in the internal space of the water receiving tub 3. A stator 30 of the motor 10 is fixed to the surface of the bottom portion 3e of the water receiving tub 3 facing the other axial side D2. The opening on the one axial side D1 of the water receiving tub 3 is closed by a door 2a that can be opened and closed.

[0015] The drum 4 has a drum cylindrical portion 4d centered on the central axis J, and a drum bottom portion 4e covering an opening on the other axial side D2 of the drum cylindrical portion 4d. That is, the drum 4 is a bottomed cylindrical body that opens on one axial side D1. A rotating shaft 40 extending from the rotor 20 of the motor 10 is fixed to the drum bottom portion 4e. That is, the drum 4 is connected to the rotor 20. This allows the drum 4 to rotate around the central axis J.

[0016] An opening on one axial side D1 of the drum 4 faces the entrance 2b. When the door 2a is open, the interior of the drum 4 is open to the front through the entrance 2b. Laundry is thrown into the drum 4 through the entrance 2b.

[0017] A plurality of through holes 4b are formed in the drum cylindrical portion 4d. The internal space of the drum 4 is connected to the external space of the drum 4 through the plurality of through holes 4b. Water introduced into the water receiving tank 3 enters the interior of the drum 4 through the through holes 4b.

[0018] A plurality of baffles 4a are fixed to the inner surface of the drum cylindrical portion 4d. Each of the baffles 4a moves in the circumferential direction about the central axis J as the drum 4 rotates. The laundry inside the drum 4 moves in the circumferential direction while being caught by each of the baffles 4a, and then falls due to gravity, thereby being agitated.

[0019] The water filling pipe 5 is disposed above the water receiving tank 3. The water filling pipe 5 is connected to a water faucet via a water supply valve or the like. The water filling pipe 5 fills water into the water receiving tank 3. The drain pipe 6 is disposed at the very bottom of the water receiving tank 3. A drain valve is provided on the drain pipe 6. The drain pipe 6 drains the water stored in the water receiving tank 3.

[0020] (First embodiment) A first embodiment of the motor 10 will now be described. FIG. 2 is a schematic cross-sectional view of the motor 10 of this embodiment. As shown in FIG. 2 , motor 10 of this embodiment is an axial gap motor. Generally, motors for rotating the drum of a washing machine are radial gap motors, in which a coil and a magnet are radially opposed. In radial gap motors, reducing the axial dimensions of the coil and magnet to achieve a thinner design reduces the opposing area between the coil and magnet, making it difficult to achieve sufficient rotational speed and rotational torque. In contrast, axial gap motors make it easy to ensure a large opposing area between the coil and magnet, making it easy to increase the rotational speed and torque of the motor even when the motor is thinned. According to this embodiment, by employing an axial gap motor as motor 10 for rotating drum 4 of washing machine 1, motor 10 can be thinned while still ensuring sufficient rotational speed and torque. Thinning motor 10, which is located behind water receiving tub 3, reduces the space behind water receiving tub 3, allowing washing machine 1 to be more compact in the front-to-rear direction.

[0021] The motor 10 comprises a rotor 20 that rotates around a central axis J, a rotating shaft 40 connected to the rotor 20, a stator 30 that faces the rotor 20 via a gap in the axial direction of the central axis J, and a bearing 5p.

[0022] The configuration of the rotor 20 will be described below. The rotor 20 is fixed to a rotating shaft 40. The rotating shaft 40 extends about a central axis J. The rotating shaft 40 is fixed to the rotor 20 and rotates together with the rotor 20 about the central axis J. The rotating shaft 40 passes through a through hole 3h provided in the center of the bottom 3e of the water receiving tub 3. A seal structure (not shown) is provided between the through hole 3h and the rotating shaft 40. The rotating shaft 40 is rotatably supported by the stator 30 via a bearing 5p. The rotating shaft 40 is fixed to the drum bottom 4e of the drum 4 at an end on one axial side D1. That is, the rotor 20 is fixed to the drum bottom 4e of the drum 4 via the rotating shaft 40. Torque of the rotor 20 is transmitted to the drum 4 via the rotating shaft 40.

[0023] The rotor 20 has a back yoke 21, a plurality of magnets 24, and a rotor holding portion 29. The rotor 20 is annular in shape and has a center on a central axis J. The back yoke 21 is located on the other axial side D2 of the magnets 24. The rotor 20 is fixed to a rotating shaft 40 at the back yoke 21.

[0024] The rotor holding portion 29 is formed by insert molding, in which the back yoke 21 and the plurality of magnets 24 are embedded. The rotor holding portion 29 holds the back yoke 21 and the plurality of magnets 24. The rotor holding portion 29 is formed, for example, from an electrically insulating resin material.

[0025] The multiple magnets 24 are arranged in a circumferential direction centered on the central axis J. The axial direction of the magnets 24 is the magnetic pole direction. The multiple magnets 24 arranged in the circumferential direction are arranged with their north and south poles alternately reversed. The magnets 24 are held by a rotor holding portion 29.

[0026] In this embodiment, the magnet 24 is a ferrite magnet, but the magnet 24 may also be another type of magnet (for example, a rare earth magnet such as a neodymium magnet).

[0027] The magnet 24 may be an anisotropic magnet or an isotropic magnet. When the magnet 24 is an anisotropic magnet, the easy axis of magnetization of the magnet 24 is set in the axial direction, thereby increasing the overall magnetic force of the magnet 24 in the axial direction. On the other hand, when an isotropic magnet is used as the magnet 24, the rotor 20 can be manufactured more inexpensively than when an anisotropic magnet is used. Figure 3 is a cross-sectional view of the rotor 20 taken along a plane perpendicular to the central axis J. As an example, the multiple magnets 24 have an isosceles trapezoidal shape when viewed from the axial direction.

[0028] The configuration of the stator 30 will be described below. Stator 30 is located on one axial side D1 of rotor 20. As described above, stator 30 is fixed to bottom 3e of water receiving tub 3. Drum bottom 4e of drum 4, bottom 3e of water receiving tub 3, stator 30, and rotor 20 are arranged in this order from one axial side D1 to the other axial side D2.

[0029] The stator 30 includes a stator core 31, a plurality of coils 35, a bearing holder 36, and a stator holding portion 39. The stator 30 has an annular shape with a central axis J as its center.

[0030] The stator core 31 has a back yoke 32 and a plurality of core portions 33. The back yoke 32 is disk-shaped and has a center on a central axis J along a plane perpendicular to the axial direction. A through hole 31h is provided in the center of the back yoke 32. A bearing holder 36 is fixed in the through hole 31h.

[0031] The bearing holder 36 has a cylindrical shape centered on the central axis line J. The bearing holder 36 holds the bearing 5p on its inner circumferential surface. The bearing holder 36 is fixed to the through hole 31h of the stator core 31.

[0032] Stator holding portion 39 is made of an electrically insulating resin material. Stator holding portion 39 is formed by insert molding, embedding stator core 31, multiple coils 35, bearing holder 36, and part of bottom 3e of water receiving tub 3. As a result, stator holding portion 39 holds stator core 31, multiple coils 35, and bearing holder 36, and also firmly fixes stator 30 to bottom 3e of water receiving tub 3.

[0033] According to this embodiment, the stator core 31 of the stator 30 contacts the bottom 3e of the water receiving tank 3. This allows heat generated by the stator 30 to be transferred to the water receiving tank 3. The water receiving tank 3 is made of a metal material and has a large heat capacity, and is cooled by water stored inside. According to this embodiment, by bringing the stator 30 into contact with the water receiving tank 3, the heat of the stator 30 is transferred to the water receiving tank 3, cooling the stator 30 and enabling stable operation of the stator 30.

[0034] According to this embodiment, stator 30 is fixed to the surface on the other axial side of bottom 3e of water receiving tub 3. Therefore, stator 30 and bottom 3e of water receiving tub 3 can be configured integrally in the axial direction, and motor 10 and water receiving tub 3 can be made smaller as a whole.

[0035] According to this embodiment, stator holding portion 39 embeds and holds at least a portion of stator 30 and at least a portion of bottom portion 3e of water receiving tub 3. This allows stator 30 and water receiving tub 3 to be handled as a single component, simplifying the assembly process.

[0036] Back yoke 32 is provided with a plurality of fixing holes 32h aligned in the circumferential direction. Fixing holes 32h pass through back yoke 32 in the axial direction. Fixing screws 34 are inserted into fixing holes 32h. Fixing screws 34 are also inserted into threaded holes 3f provided in bottom 3e of water receiving tub 3. In this way, stator core 31 is fixed to the surface of bottom 3e of water receiving tub 3 facing the other axial side.

[0037] FIG. 4 is a schematic cross-sectional view of motor 10 taken along a plane including central axis J. In FIG. 4, the other axial side D2 is the upper side, and one axial side D1 is the lower side. That is, in FIG. 4, rotor 20 is disposed on the upper side, and stator 30 is disposed on the lower side. Only one radial side of motor 10 from central axis J is shown schematically in FIG. 4.

[0038] As shown in Fig. 4, the multiple core portions 33 protrude toward the other axial side D2 from a surface of the back yoke 32 facing the other axial side D2. Fig. 5 is a cross-sectional view of the stator 30 taken along a plane perpendicular to the central axis J. As shown in Fig. 5, the multiple core portions 33 are arranged at equal intervals along the circumferential direction of the central axis J. As an example, the core portions 33 have an isosceles trapezoidal shape when viewed from the axial direction. When viewed from the axial direction, two parallel sides of the core portions 33 extend perpendicular to the radial direction of the central axis J.

[0039] The core portion 33 is located on the inner diameter side of the coil 35 in the back yoke 32. The core portion 33 protrudes toward the other axial side D2 from the surface of the back yoke 32 facing the other axial side D2. The core portion 33 extends toward the other axial side D2 along the inner diameter of the coil 35. An end face of the core portion 33 on the other axial side D2 faces the magnet 24 in the axial direction. The end face of the core portion 33 is flush with the end face of the coil 35 on the other axial side D2 and the end face of the stator holding portion 39 on the other axial side D2.

[0040] The core portion 33 is formed of a magnetic material that magnetically circulates with the back yoke 32. As an example, the back yoke 32 is formed of electromagnetic steel plates laminated in the axial direction. As an example, the core portion 33 is formed of a material having the same magnetic permeability as the back yoke 32. The core portion 33 is formed of the same material as the back yoke 32. As an example, the core portion 33 is formed by fixing a core member 33A, which is formed separately from the back yoke 32 and made of a material having the same magnetic permeability as the back yoke 32, to the back yoke 32 by gluing or fitting by crimping or the like. It is also possible to form the core portion 33 and the back yoke 32 by cutting out a single piece of metal material.

[0041] The coils 35 are wound around the core portions 33. As shown in FIG. 5, the coils 35 are attached to the multiple core portions 33, respectively. The multiple coils 35 are arranged in the circumferential direction. Ends of the coils 35 are drawn out from the stator 30 and connected to a power supply. This allows current to flow through the coils 35. Each coil 35 is wound around an axis parallel to the central axis J. Therefore, when a current is passed through the coils 35, they form magnetic poles in the axial direction. That is, the coils 35 form magnetic poles on the rotor 20 side, which faces them in the axial direction.

[0042] The coil 35 may be wound around the core portion 33 via an insulator (not shown). The insulator (not shown) may be, for example, bobbin-shaped and made of an electrically insulating resin material. The coil 35 may be covered with an electrically insulating resin material when it is insert-molded into the stator holding portion 39.

[0043] According to this embodiment, the core portion 33, which is formed of a magnetic material that magnetically circulates with the back yoke 32, is located on the inner diameter side of the coil 35 on the back yoke 32. FIG. 6 is a diagram showing the relationship between radial position and magnetic distribution. The radial position R1 in FIG. 6 is the radially inner position of the core portion 33 shown in FIG. 4. The radial position R2 in FIG. 6 is the radially outer position of the core portion 33. The magnetic distribution M1 in FIG. 6 is the magnetic distribution when the core portion 33 is provided. By arranging the magnetic material connected to the back yoke 32 on the inner diameter side of the coil 35, the magnetic return flow to the magnet 24 is strengthened. Therefore, according to this embodiment, by providing the core portion 33 as shown in FIG. 6, the magnetic distribution M1 can be adjusted to be larger than the magnetic distribution when the core portion 33 is not provided in the stator 30.

[0044] (Second embodiment) A second embodiment of the motor 10 will be described below with reference to FIGS. In these figures, the same elements as those in the first embodiment shown in FIGS. 1 to 6 are denoted by the same reference numerals, and the description thereof will be omitted.

[0045] 7 is a schematic cross-sectional view of the motor 10 of the second embodiment taken along a plane including the central axis J. As shown in FIG. 7, the motor 10 of the second embodiment has a back yoke 32 provided with a plurality of core portions 33B.

[0046] The core portion 33B protrudes toward the other axial side D2 from a surface of the back yoke 32 facing the other axial side D2. The core portion 33B is located on the inner diameter side of the coil 35 in the back yoke 32. The core portion 33B is formed of a magnetic material having a different magnetic permeability from the material forming the back yoke 32. Specifically, the core portion 33B is formed of a material having a higher magnetic permeability than the material forming the back yoke 32. The other configurations are the same as those of the first embodiment.

[0047] FIG. 8 is a diagram showing the relationship between radial position and magnetic distribution in the second embodiment. Magnetic distribution M2 in FIG. 8 is the magnetic distribution when core portion 33B is provided. According to this embodiment, core portion 33B, which is formed of a material having a higher magnetic permeability than the material forming back yoke 32, is provided on the inner diameter side of coil 35. Therefore, the magnetic return flow to magnet 24 is stronger than when core portion 33 having the same magnetic permeability as back yoke 32 is provided. Therefore, as shown in FIG. 8, by providing core portion 33B having a higher magnetic permeability than the material forming back yoke 32, magnetic distribution M2 can be adjusted to be stronger than magnetic distribution M1 when core portion 33 is provided. In other words, by using a ferromagnetic material for core portion 33B, a stronger magnetic field can be generated.

[0048] In the second embodiment, the core portion 33B is formed of a material having a higher magnetic permeability than the material forming the back yoke 32. However, the core portion 33B may be formed of a material having a lower magnetic permeability than the material forming the back yoke 32. When this configuration is adopted, it becomes possible to adjust the magnetic distribution to be smaller than the magnetic distribution M1 when the core portion 33 is provided. When the core portion 33B is formed of a magnetic material having a lower magnetic permeability than the magnetic material forming the back yoke 32, the core portion 33B can be formed of a dust core. When the core portion 33B is formed of a dust core, simple shapes as well as any complex shape can be easily manufactured.

[0049] (Third embodiment) A third embodiment of the motor 10 will be described below with reference to FIGS. In these figures, the same elements as those in the second embodiment shown in FIGS. 7 and 8 are denoted by the same reference numerals, and the description thereof will be omitted.

[0050] FIG. 9 is a cross-sectional schematic diagram of a motor 10 according to a third embodiment taken along a plane including the central axis J. As shown in FIG. 9, in the motor 10 according to the third embodiment, a plurality of first core portions 33C and a plurality of second core portions 33D are provided in the back yoke 32. The first core portions 33C are axially shaped and extend in the axial direction on the inner diameter side of the coils 35. The first core portions 33C are formed of a magnetic material having a first magnetic permeability. The first magnetic permeability is the same as the magnetic permeability of the magnetic material forming the back yoke 32. The first core portions 33C are formed of the same magnetic material as the magnetic material forming the back yoke 32.

[0051] The second core portion 33D is disposed annularly around the first core portion 33C on the inner diameter side of the coil 35. The end faces of the tips of the first core portion 33C and the second core portion 33D on the other axial side D2 are planes parallel to a plane perpendicular to the central axis J. The end faces of the tips of the first core portion 33C and the second core portion 33D on the other axial side D2 are flush with each other. The end faces of the first core portion 33C and the second core portion 33D on the other axial side D2 are flush with the end face of the coil 35 on the other axial side D2 and the end face of the stator holding portion 39 on the other axial side D2. The second core portion 33D is formed of a magnetic material having a second magnetic permeability. The second magnetic permeability is smaller than the first magnetic permeability. That is, the second core portion 33D is a weakly magnetic material relative to the first core portion 33C and the back yoke 32. The second core portion 33D is a dust core fixed to the back yoke 32. When the second core portion 33D is formed of a dust core, it is possible to easily manufacture not only simple shapes but also any complex shape. The other configurations are the same as those of the second embodiment.

[0052] 10 and 11 are diagrams showing the relationship between radial position and magnetic distribution in the third embodiment. Radial position R11 in FIGS. 10 and 11 is the radially inner position of the first core portion 33C shown in FIG. 9. Radial position R12 in FIG. 9 is the radially outer position of the first core portion 33C. Radial position R1 in FIGS. 10 and 11 is the radially inner position of the second core portion 33D shown in FIG. 9. Radial position R2 in FIGS. 10 and 11 is the radially outer position of the second core portion 33D shown in FIG. 9.

[0053] 10 , according to this embodiment, when a strong current is supplied to the coil 35, the stator 30 can be adjusted to a large magnetic distribution M1 between radial positions R11 and R12 where the first core portion 33C is located. When a strong current is supplied to the coil 35, the stator 30 can be adjusted to a magnetic distribution M3, which is smaller than the magnetic distribution M1, between radial positions R1 and R11 and between positions R12 and R2 where the second core portion 33D is located. In other words, according to this embodiment, when a strong current is supplied to the coil 35, the magnetic field can be adjusted to a drum-shaped magnetic field in which both radial sides of the magnetic distribution M1 become magnetic distribution M3, which is smaller than the magnetic distribution M1, at positions on the inner diameter side of the coil 35. Therefore, the magnetic distribution on the stator 30 side can be adjusted to a substantially sinusoidal wave.

[0054] 11 , according to this embodiment, when a weak current is supplied to the coil 35, the magnetic distribution can be adjusted to M1 only between radial positions R11 and R12 where the first core portion 33C is located in the stator 30. The influence of the magnetic distribution between radial positions R11 and R11 where the second core portion 33D is located and between positions R12 and R2 is negligibly small. Therefore, by switching the power supply to the coil 35 between a strong current and a weak current, it is possible to switch between a drum-shaped magnetic distribution having magnetic distributions M1 and M2 and a locally protruding magnetic distribution having the magnetic distribution M1.

[0055] Therefore, in the washing machine 1 equipped with the motor 10 of the third embodiment, it is easier to generate large power during washing, which requires high torque, and during spin-drying, which requires high rotation speed, the back electromotive force is suppressed, making it easier to generate high rotation speed.

[0056] In the third embodiment described above, a configuration in which the first core portion 33C and the second core portion 33D are provided on the inner diameter side of the coil 35 is exemplified, but this configuration is not limiting. For example, a configuration in which one or more core portions are further provided in a ring shape around the second core portion 33D may be adopted. When this configuration is adopted, it is preferable to make the magnetic permeability of the core portions located outside the second core portion 33D sequentially smaller than the second magnetic permeability. This allows the magnetic distribution having a drum-shaped step portion to be adjusted to a more sinusoidal wave shape.

[0057] (Fourth embodiment) A fourth embodiment of the motor 10 will be described below with reference to FIGS. In these figures, the same elements as those in the third embodiment shown in FIGS. 9 to 11 are denoted by the same reference numerals, and the description thereof will be omitted.

[0058] 12 is a schematic cross-sectional view of a motor 10 of the fourth embodiment taken along a plane including the central axis J. As shown in FIG. 12, in the motor 10 of the fourth embodiment, the end face of the tip of the second core portion 33D on the other axial side D2 is located closer to the one axial side D1 than the end face of the tip of the first core portion 33C on the other axial side D2. In other words, the distance from the back yoke 32 to the axial tip of the second core portion 33D is shorter than the distance from the back yoke 32 to the axial tip of the first core portion 33C. The rest of the configuration is the same as that of the third embodiment.

[0059] FIG. 13 is a diagram showing the relationship between radial position and magnetic distribution in the fourth embodiment. According to this embodiment, the distance from the back yoke 32 to the axial tip of the second core portion 33D is shorter than that of the second core portion 33D shown in Fig. 9, thereby suppressing magnetic reflux. Therefore, as shown in Fig. 13, the magnetic field can be adjusted to a drum-shaped magnetic distribution M4, which is smaller than the magnetic distribution M3 shown in Fig. 10, between radial positions R1 and R11 where the second core portion 33D is located and between positions R12 and R2. Therefore, the magnetic field can be adjusted to a substantially sinusoidal wave shape with a large difference in magnetic distribution.

[0060] When a weak current is supplied to the coil 35, as shown in FIG. 11, the magnetic distribution can be adjusted to M1 only between the radial positions R11 and R12 where the first core portion 33C is located in the stator 30.

[0061] In the above-described third embodiment, one end face of the tip of the second core portion 33D on the other axial side D2 is positioned closer to the first axial side D1 than the end face of the tip of the first core portion 33C on the other axial side D2. However, this configuration is not limited to this. For example, the end face of the tip of the second core portion 33D on the other axial side D2 may have multiple steps whose distance from the back yoke 32 gradually decreases with increasing distance from the first core portion 33C. With this configuration, magnetic return current is gradually suppressed with increasing distance from the first core portion 33C. Therefore, the magnetic distribution can be adjusted to a drum-shaped magnetic field that gradually decreases with increasing distance from the first core portion 33C.

[0062] (Fifth embodiment) A fifth embodiment of the motor 10 will be described below with reference to FIGS. In these figures, the same elements as those in the fourth embodiment shown in FIGS. 12 and 13 are denoted by the same reference numerals, and the description thereof will be omitted.

[0063] 14 is a schematic cross-sectional view of a motor 10 according to a fifth embodiment taken along a plane including the central axis J. The motor 10 according to the fifth embodiment differs from the motor according to the fourth embodiment in the shape of the tip of the second core portion 33D on the other axial side D2. As shown in FIG. 14, the tip of the second core portion 33D on the other axial side D2 has a base point at the edge of the tip of the first core portion 33C on the other axial side D2, and approaches the back yoke 32 as it moves away from the first core portion 33C. The tip of the second core portion 33D has an inclined surface that slopes toward the back yoke 32 as it moves away from the first core portion 33C.

[0064] FIG. 15 is a diagram showing the relationship between the radial position and the magnetic distribution in the fifth embodiment. According to this embodiment, the distance between the tip of the second core portion 33D and the back yoke 32 becomes shorter as the distance from the first core portion 33C increases. Therefore, as shown in Fig. 15, magnetic circulation is suppressed as the distance from the radial positions R11 and R12 where the first core portion 33C is located increases, and the magnetic distribution can be continuously reduced from M1 to M4. Therefore, the magnetic field can be adjusted to have a substantially sinusoidal shape in which the magnetic distribution changes continuously.

[0065] When a weak current is supplied to the coil 35, as shown in FIG. 11, the magnetic distribution can be adjusted to M1 only between the radial positions R11 and R12 where the first core portion 33C is located in the stator 30.

[0066] In the fifth embodiment, the tip of the second core portion 33D is an inclined surface that approaches the back yoke 32 as it moves away from the first core portion 33C, but the present invention is not limited to this configuration. The tip of the second core portion 33D may be an arc-shaped curved surface that approaches the back yoke 32 as it moves away from the first core portion 33C. By adopting this configuration, the magnetic field can be adjusted to a substantially sinusoidal shape in which the magnetic distribution changes continuously along the polar line.

[0067] In the third to fifth embodiments, a configuration using a first core portion 33C having the same magnetic permeability as the magnetic material forming the back yoke 32 and a second core portion 33D having a magnetic permeability lower than that of the magnetic material forming the back yoke 32 was illustrated, but the present invention is not limited to this configuration. For example, a configuration using a first core portion 33C having a higher magnetic permeability than the magnetic material forming the back yoke 32 and a second core portion 33D having the same magnetic permeability as the magnetic material forming the back yoke 32 may be used. For example, a configuration using a first core portion 33C having a higher magnetic permeability than the magnetic material forming the back yoke 32 and a second core portion 33D having a lower magnetic permeability than the magnetic material forming the back yoke 32 may be used. Furthermore, for example, a configuration using a first core portion 33C and a second core portion 33D having a higher magnetic permeability than the magnetic material forming the back yoke 32 may be used. Furthermore, for example, a configuration using a first core portion 33C and a second core portion 33D having a lower magnetic permeability than that of the magnetic material forming the back yoke 32 may be used.

[0068] According to at least one of the embodiments described above, by having a plurality of coils 35 arranged circumferentially on back yoke 32 and facing magnet 24 in the axial direction to form magnetic poles, and core portion 33 located on the inner diameter side of coils 35 on back yoke 32 and formed of a magnetic material that magnetically circulates with back yoke 32, it is possible to easily adjust the magnetic characteristics in thin axial gap type motor 10 and washing machine 1.

[0069] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention described in the claims and their equivalents.

[0070] In the above embodiment, a drum-type washing machine is exemplified as a washing machine employing the configuration of the present invention. However, the configuration of the present invention may also be employed in a vertical washing machine. [Explanation of symbols]

[0071] 1... washing machine, 3... water receiving tub, 4... drum (rotating tub), 10... motor, 20... rotor, 24... magnet, 30... stator, 32... back yoke, 33, 33B... core portion, 33A... core member, 33C... first core portion, 33D... second core portion, 35... coil, J... central axis

Claims

1. a rotor that rotates about a central axis; a stator facing the rotor across a gap in the axial direction of the central axis; Equipped with The rotor is a plurality of magnets arranged along a circumferential direction and having magnetic poles in an axial direction; a rotor holding portion having a first opposing surface facing the stator and holding the plurality of magnets; and The stator includes: a back yoke along a plane perpendicular to the axial direction; a plurality of coils arranged along a circumferential direction on the back yoke and facing the magnet in an axial direction to form magnetic poles; a core portion located on an inner diameter side of the coil in the back yoke and formed of a magnetic material that magnetically circulates with the back yoke; a stator holding portion having a second opposing surface facing the rotor and holding the plurality of coils; and the plurality of magnets are held by the rotor holding portion so as to be flush with the first opposing surface, the plurality of coils are held by the stator holding portion so as to be flush with the second opposing surface, The rotor is disposed outside the water receiving tub in a washing machine including a rotatable tub and a water receiving tub that accommodates the rotatable tub, The stator holding portion is an insert-molded body in which a portion of the bottom of the water receiving tank is embedded.

2. At least a part of the core portion is formed of a magnetic material having a different magnetic permeability from that of the back yoke. The motor according to claim 1 .

3. The core portion is a dust core fixed to the back yoke or a core member fitted into the back yoke.

3. The motor according to claim 1 or 2.

4. The core portion has a first core portion having a first magnetic permeability and a second core portion having a second magnetic permeability smaller than the first magnetic permeability.

3. The motor according to claim 1 or 2.

5. The second core portion is a dust core fixed to the back yoke. The motor according to claim 4.

6. the first core portion has a shaft shape extending in the axial direction on the inner diameter side of the coil, The motor according to claim 4 or 5, wherein the second core portion is disposed annularly around the first core portion on an inner diameter side of the coil.

7. an axial end of the first core portion and an axial end of the second core portion are parallel to the plane, a distance from the back yoke to a tip of the second core portion in the axial direction is shorter than a distance from the back yoke to a tip of the first core portion in the axial direction; The motor according to claim 6.

8. The axial tip of the first core portion is a surface parallel to the plane, an axial tip of the second core portion approaches the back yoke as it moves away from the first core portion, with the edge of the tip of the first core portion as a base point; The motor according to claim 6.

9. The axial tip of the second core portion is an inclined surface or a curved surface. The motor according to claim 8.

10. A motor according to any one of claims 1 to 9; the rotating tub is cylindrical with a bottom that opens to one axial side of the central axis and is rotated by the motor; The water receiving tank accommodates the rotating tank, The rotor is connected to the rotary tub, The stator contacts the bottom of the water receiving tank. washing machine.

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