JP7240872B2 - Linear motors, electromagnetic suspensions and washing machines - Google Patents

Description

The present invention relates to linear motors, electromagnetic suspensions and washing machines.

Linear motors and linear actuators (hereinafter collectively referred to as linear motors) are known as electric machines that move linearly. A linear motor has a structure in which a rotating machine is linearly cut open, and a magnetic force acting between magnetic poles formed on each of a stator and a mover generates a thrust force on the mover. In addition, studies are underway to utilize linear motors as electromagnetic suspensions. For example, Patent Literature 1 and Patent Literature 2 describe techniques for applying an electromagnetic suspension having a linear motor as a suspension for a washing machine.

JP 2017-200336 A JP 2011-106571 A

A mover of the linear motor disclosed in Patent Documents 1 and 2 is equipped with a plurality of magnets along the movement direction so that the magnetization directions are alternately reversed. If the number of magnets increases in this way, there is a problem that the assembly becomes complicated and the cost increases.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a linear motor, an electromagnetic suspension, and a washing machine that can be realized at low cost.

In order to solve the above problems, the linear motor of the present invention has a stator having an armature core and an armature winding, a first surface and a second surface facing the stator, a mover that moves relative to the stator along a predetermined moving direction, wherein the armature core includes first magnetic teeth facing the first surface; a second magnetic tooth facing the surface and adjacent to the first magnetic tooth along the direction of movement; a third magnetic tooth facing the second surface; and a third magnetic tooth facing the second surface. and a fourth magnetic tooth adjacent to the third magnetic tooth along the direction of movement, wherein the mover is positioned between the center of the first magnetic tooth and the center of the second magnetic tooth. When the distance in the movement direction of the magnetic tooth pitch is the magnetic tooth pitch, the first surface is the S pole or the N pole over a section longer than 0.8 times the magnetic tooth pitch along the movement direction. The second surface is magnetized to the other pole, either the S pole or the N pole, over a section longer than 0.8 times the magnetic tooth pitch along the moving direction. The mover has an S pole surface magnetized to the S pole over a distance longer than 0.8 times the magnetic tooth pitch along the moving direction, and a magnetic tooth pitch longer than 0.8 times the magnetic tooth pitch. a plate-shaped magnet having an N pole surface magnetized to the N pole over a long distance, and a frame formed of a material having a lower magnetic permeability than the magnet and holding the magnet, A position in which one end of the magnet reaches the outer end of the first magnetic tooth is defined as a first position, and a position in which the other end of the magnet reaches the outer end of the second magnetic tooth in the moving direction is defined as a second position. , the width of each of the first to fourth magnetic teeth is longer than the range length, which is the moving distance of the mover from the first position to the second position. and

According to the present invention, a linear motor, an electromagnetic suspension, and a washing machine can be realized at low cost.

BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional perspective view of the linear motor which concerns on 1st Embodiment of this invention. FIG. 2 is a schematic cross-sectional view taken along line II-II of FIG. 1; FIG. 2 is a schematic cross-sectional view taken along line III-III in FIG. 1; It is an exploded perspective view of a mover in a 1st embodiment. FIG. 4 is an operation explanatory diagram of the linear motor according to the first embodiment; It is a schematic diagram of the linear motor by 1st Embodiment and a modification. FIG. 5 is a thrust characteristic diagram of the linear motors according to the first embodiment and a modified example; It is a schematic diagram of the linear motor by a modification. FIG. 5 is a perspective view of an electromagnetic suspension according to a second embodiment of the invention; FIG. 10 is a perspective view of a washing machine according to a third embodiment of the present invention; It is a longitudinal cross-sectional view of the washing machine by 3rd Embodiment. It is a block diagram of the damping apparatus applied to 3rd Embodiment. It is a block diagram of the principal part of the vibration damping apparatus applied to 3rd Embodiment. It is a figure which shows the rotation speed of a washing-tub, and the displacement of the outer tub 37 in a comparative example. It is a figure which shows the rotation speed of a washing-tub, and the displacement of the outer tub 37 in 4th Embodiment.

[First embodiment]
<Configuration of the first embodiment>
FIG. 1 is a cross-sectional perspective view of a linear motor 10 according to a first embodiment of the invention. The linear motor 10 is applied, for example, to an electromagnetic suspension 100 (see FIG. 9) of another embodiment described later, and the electromagnetic suspension 100 is applied, for example, to suppress vibration of the washing machine W (see FIG. 10). be.
The x-, y-, and z-axes are defined as indicated by x, y, and z in FIG. FIG. 1 shows a bird's-eye view of the appearance of the linear motor 10, and shows the internal structure by cutting 1/4 of it. The linear motor 10 includes a stator 11 which is an armature, a plate-like mover 12 extending in the z-axis direction, and rollers 13 supporting the mover 12 so as to be slidable in the z-axis direction. .

The stator 11 is formed in a substantially cylindrical shape along the z-axis direction, and a rectangular plate-like mover 12 is loosely inserted in the hollow portion thereof. The linear motor 10 changes the relative position between the stator 11 and the mover 12 in the z-axis direction by magnetic attraction and repulsion acting between the stator 11 and the mover 12, that is, thrust force. . When the linear motor 10 is applied to the electromagnetic suspension 100, the mover 12 is coupled to a damping object. In the example shown in FIG. 1, the outer tub 37 (see FIG. 10) of the washing machine W is the object to be damped, and the mover 12 is coupled to the outer tub 37 .

The stator 11 includes a core 11a (armature core) and windings 11b (armature winding). The core 11a is formed by stacking electromagnetic steel sheets in the z-axis direction, and includes a magnetic tooth 151 (first magnetic tooth) and a magnetic tooth 152 (second magnetic tooth) protruding toward the mover 12 adjacent to each other along the z-axis direction. 2 magnetic teeth); Further, as shown in FIG. 5, the core 11a has a magnetic tooth 153 (a magnetic tooth 153 ( a third magnetic tooth) and a magnetic tooth 154 (fourth magnetic tooth).

The winding 11b is wound around these magnetic teeth 151-154. The core 11a also has a commutating pole portion 160 between the magnetic teeth 151 and 152, on which no winding is wound. The commutating pole portion 160 has commutating pole teeth 162 and 164 at positions facing each other with the mover 12 interposed therebetween (see FIG. 3).
The mover 12 also includes a frame 122 made of nonmagnetic material and a magnet 124 fitted in the frame 122 .

FIG. 2 is a schematic cross-sectional view taken along line II-II of FIG. However, the 1/4 portion cut in FIG. 1 is not cut in FIG.
As shown in FIG. 2 , the core 11 a of the stator 11 has an annular portion 156 and magnetic teeth 151 and 153 .
The annular portion 156 has an annular shape, that is, a substantially rectangular frame shape when viewed in longitudinal section, and the annular portion 156 constitutes a magnetic circuit. A pair of magnetic teeth 151 and 153 extend inward along the y-axis direction from the annular portion 156 and face each other. The gap between the magnetic teeth 151 and 153 is slightly wider than the thickness of the plate-shaped mover 12 .

A magnetic flux ΦA indicated by a solid line arrow is a magnetic flux generated by the mover 12 . Windings 11b are wound around the magnetic teeth 151 and 153, respectively. The magnetic teeth 152 and 154 (see FIG. 5) are constructed similarly to the magnetic teeth 151 and 153. As shown in FIG. An inverter (for example, an inverter 40 in FIG. 13, which will be described later) is connected to the winding 11b. When the winding 11b is energized by the inverter, the stator 11 functions as an electromagnet.

FIG. 3 is a schematic cross-sectional view taken along line III--III in FIG. However, the 1/4 portion cut in FIG. 1 is not cut in FIG.
As shown in FIG. 3 , the commutating pole portion 160 of the core 11 a includes an annular portion 166 and commutating pole teeth 162 and 164 .
The annular portion 166 has an annular shape, that is, a substantially rectangular frame shape when viewed in longitudinal section, and the annular portion 166 constitutes a magnetic circuit. Commutating pole teeth 162 and 164 extend inward in the y-axis direction from annular portion 166 and face each other. The gap between the commutating pole teeth 162 and 164 is slightly wider than the thickness of the plate-like mover 12 . However, the commutating pole teeth 162 and 164 are not wound with windings. A magnetic flux ΦB indicated by a dashed arrow is a magnetic flux generated by the mover 12 .

4 is an exploded perspective view of the mover 12. FIG. As described above, mover 12 includes frame 122 and magnet 124 . The frame 122 is made of a non-magnetic material and shaped like a rectangular frame. A rectangular through-hole 122h is formed in the frame 122 so as to penetrate the front surface 122f (first surface) and the rear surface 122r (second surface). The magnet 124 is formed integrally with the through hole 122h and in a rectangular plate shape having substantially the same dimensions, and is mounted in the through hole 122h.

Further, in order to improve the responsiveness of the linear motor 10, it is desirable that the mover 12 be lightweight. Therefore, it is conceivable to use a lightweight material such as plastic or aluminum as the non-magnetic material forming the frame 122 . Also, a lightweight and high-strength composite material such as carbon fiber reinforced plastic may be applied. That is, the material of the frame 122 may be arbitrarily selected according to the required strength and specifications of the linear motor 10 .

Also, the magnet 124 is magnetized in the y-axis direction. That is, the magnet 124 has an S pole surface 124S, which is one surface thereof, magnetized to the S pole, and an N pole surface 124N, which is the rear surface of the S pole surface 124S, is magnetized to the N pole. When the magnet 124 is fitted into the frame 122, the S pole surface 124S of the magnet 124 is exposed from the surface 122f side of the through hole 122h, and the N pole surface 124N of the magnet 124 is exposed from the rear surface 122r side of the through hole 122h.

As the magnet 124, it is desirable to use a samarium-iron-nitrogen based magnet. Specific ratios (% by weight) of the raw materials of the magnet 124 are, for example, iron: approximately 73%, samarium: approximately 24%, and nitrogen: approximately 3%. Among the raw materials mentioned above, the rare earth element is samarium. On the other hand, in conventional neodymium magnets, iron: about 65%, neodymium: about 28%, dysprosium: about 5%, and boron: about 2% were often used. Among the raw materials mentioned above, the rare earth elements are neodymium and dysprosium. Therefore, since the samarium-iron-nitrogen based magnet 124 has a smaller ratio of rare earth elements than the conventional neodymium magnet, it is less susceptible to market trends and can improve productivity.

Furthermore, unlike conventional neodymium magnets and ferrite magnets, the samarium-iron-nitrogen magnet 124 can be kneaded into resin and molded. Therefore, the machining accuracy of the magnet 124 can be improved and the dimensional variation can be reduced compared to the conventional art. In addition, even if a wasteful portion of the raw material remains in molding the magnet 124, it can be reused. The shape of the magnet 124 is not limited to the rectangular plate shape described above, but it is desirable to adopt a simple shape that is easy to mold, such as a rectangular parallelepiped shape or a flat plate shape other than a rectangle. In particular, if the flat plate shape shown in FIG. 4 is adopted as the shape of the magnet 124, high efficiency can be realized in that the magnetic pole area can be increased while reducing the amount of magnet used.

5A and 5B are operation explanatory diagrams of the linear motor 10. FIG.
States P1, P2 (first position), and P3 (second position) shown in FIG. In FIG. 5 , the solid-line thick arrow indicates the direction of the magnetic flux generated by the magnet 124 , and the broken-line thick arrow indicates the direction of the magnetic flux generated by the stator 11 . In any of the states P1 to P3, the magnetic teeth 151 and 152 face the front surface 122f of the frame 122, and the magnetic teeth 153 and 154 face the back surface 122r of the frame 122. FIG.

The width of each magnetic tooth 151 to 154 in the z-axis direction is the same, and this width is called "magnetic tooth width TL (width)". Also, the center positions of the magnetic teeth 151 and 152 in the z-axis direction are referred to as center positions 151c and 152c. The center positions 151c and 152c are also equal to the center positions of the magnetic teeth 153 and 154 in the z-axis direction. Here, the distance between the center positions 151c and 152c is called "magnetic tooth pitch TP". Also, the length of the magnet 124 in the z-axis direction is called magnet length ML.

In state P1 of FIG. 5, the stator 11 does not generate magnetic flux because the winding 11b is not energized. Further, the center (no sign) of the stator 11 in the z-axis direction coincides with the center (no sign) of the mover 12 . Also, when a current is passed through the winding 11b, the magnetic teeth 151 to 154 can be magnetized according to the direction of the current. In the state P1, magnetizing the magnetic teeth 151 and 154 to the north pole and magnetizing the magnetic teeth 152 and 153 to the south pole, similar to the symbols "N" and "S" shown in the state P2, magnetizes the magnet 124 are attracted to magnetic teeth 151 and 153 and repelled to magnetic teeth 152 and 154 .

In this way, due to the attractive force and the repulsive force acting between the stator 11 and the mover 12, a relative thrust force acts on the stator 11 and the mover 12 along the z-axis direction. The “thrust force” is a force that changes the relative position between the mover 12 and the stator 11 . Therefore, as shown in state P2, for example, the mover 12 is biased relative to the stator 11 in the z-axis plus direction (leftward direction in the figure) and moves.

Conversely, in state P1, similarly to the symbols "N" and "S" shown in state P3, if the magnetic teeth 151 and 154 are magnetized to the south pole and the magnetic teeth 152 and 153 are magnetized to the north pole, , magnet 124 is repelled by magnetic teeth 151 and 153 and attracted to magnetic teeth 152 and 154 . Therefore, as shown in state P3, for example, the mover 12 is biased relative to the stator 11 in the negative direction of the z-axis (to the right in the figure) and moves.

In state P2, the left end 124a (one end) of the magnet 124 and the left end 151a (outer end) of the magnetic tooth 151 are aligned in the z-axis direction. In state P3, the right end 124b (other end) of the magnet 124 and the right end 152b (outer end) of the magnetic tooth 152 are aligned in the z-axis direction. The moving range of the mover 12 from the state P2 to the state P3 is called the "normal range", and the length of the normal range is called the "normal range length UL (range length)". It should be noted that the stator 11 and the mover 12 can be moved relative to each other beyond the normal use range, but if the normal use range is exceeded, the linearity deteriorates and the control becomes complicated. Therefore, in this embodiment, it is assumed that the linear motor 10 is mainly driven in the normal range.

Here, as shown in FIG. 5, the magnet 124 is desirably composed of one integrally molded magnet, the magnetic tooth width TL is longer than the normal use range length UL, and the magnet length ML is equal to the magnetic tooth pitch. It is desirable to make it longer than TP. With this configuration, all of the magnetic teeth 151 to 154 and the commutating pole portion 160 can face the magnet 124 within the range of normal use.

As in Patent Documents 1 and 2 described above, in a generally known linear motor, a plurality of magnets are attached to the mover along the movement direction so that the magnetization directions are alternately reversed. Then, the state of magnetic transfer between the magnetic teeth, the commutating poles, the magnets, and the like changes every moment, so the thrust pulsates and becomes difficult to control. In contrast, according to the structure of the linear motor 10 of the present embodiment, the magnetic transfer relationship between the magnetic teeth 151 to 154, the commutating pole portion 160, and the magnet 124 within the normal use range of the mover 12. can be stabilized and constant, high robustness can be achieved.

FIG. 6 is a schematic diagram of the linear motor 10 of the present embodiment and linear motors 10A and 10B of modifications.
As described with reference to FIG. 5, the linear motor 10 of the present embodiment has a magnetic tooth width TL longer than the normal range length UL, a magnet length ML longer than the magnetic tooth pitch TP, and a single magnet 124. It has the characteristic of

On the other hand, in the linear motor 10A of the modified example, the magnet length ML is substantially the same as the magnetic tooth pitch TP (more precisely, the magnet length ML is slightly longer than the magnetic tooth pitch TP). Other configurations of the linear motor 10A are the same as those of the linear motor 10. FIG. Therefore, the linear motor 10A has the characteristics that "the magnetic tooth width TL and the normal range length UL are substantially the same, the magnet length ML and the magnetic tooth pitch TP are substantially the same, and the number of the magnets 124 is one." have.

Also, in the linear motor 10B of another modified example, the magnet length ML is approximately 0.8 times the magnetic tooth pitch TP. Other configurations of the linear motor 10B are the same as those of the linear motor 10. FIG. Therefore, the linear motor 10B has characteristics that "the magnetic tooth width TL is shorter than the normal range length UL, the magnet length ML is shorter than the magnetic tooth pitch TP, and the number of magnets 124 is one."

FIG. 7 is a thrust force characteristic diagram of the linear motor 10 of the present embodiment and linear motors 10A and 10B of modifications.
The horizontal axis of FIG. 7 represents the position of the mover 12, with one end of the normal use range (the position shown in FIG. 6) of each linear motor 10, 10A, 10B being -100%, and the other end of the normal use range being +100%. , and the intermediate position (for example, state P1 in FIG. 5) is set to 0%.

The vertical axis in FIG. 7 is the thrust of the linear motors 10, 10A, and 10B, and the thrust FC1 in the figure is the target thrust. Within the normal use range, the flatter the thrust characteristic, the higher the controllability of the linear motor 10 . Further, the range of thrust FC1±ΔFC has a deviation of ±20% from the target thrust FC1. When applying the linear motor 10 to an electromagnetic suspension 100 (see FIG. 9), which will be described later, it is preferable to suppress the deviation of the thrust force FC within the range of ±ΔFC.

A thrust characteristic Q indicated by white circles and a dashed line in FIG. 7 is the thrust characteristic of the linear motor 10 of the present embodiment. According to the thrust force characteristic Q, the thrust force FC can be kept within the range of FC1±ΔFC within the normal use range, and the thrust force FC is substantially constant. Therefore, it can be seen that the linear motor 10 of this embodiment is easy to control and suitable for application to an electromagnetic suspension.

A thrust characteristic QA indicated by black circles and a solid line in FIG. 7 is the thrust characteristic of the linear motor 10A of the modified example shown in FIG. According to the thrust characteristic QA, similarly to the thrust characteristic Q of this embodiment, the thrust FC can be kept within the range of FC1±ΔFC within the normal range, and the thrust FC is substantially constant. Therefore, it can be seen that the linear motor 10A of this modified example is also easy to control and suitable for application to an electromagnetic suspension.

A thrust characteristic QB indicated by white triangles and a solid line in FIG. 7 is the thrust characteristic of the linear motor 10B of another modified example. According to the thrust characteristic QB, the thrust FC is lower than FC1-ΔFC when the position of the mover 12 is around ±100%. The shape of the thrust characteristic Q3 is also distorted in the vicinity of ±80% to ±100%. For this reason, the linear motor 10B is sufficiently practical, but if it is applied to an electromagnetic suspension, the control may become somewhat complicated.

Here, the suitability of applying the linear motors 10, 10A, and 10B to the electromagnetic suspension will be further examined. Ideally, the characteristic of the thrust FC is desired to achieve a flat characteristic equal to or greater than the target thrust FC1 in the normal use range. However, unlike a continuous track rotary motor, an electromagnetic suspension having ends tends to exhibit different characteristics at the left end, center, and right end of its movable range. The thrust characteristics Q, QA, and QB shown in FIG. 7 are also lower at the left and right ends than at the center.

When the linear motors 10, 10A, 10B are applied to an electromagnetic suspension, the linear motors 10, 10A, 10B urge the mover 12 in a direction that suppresses vibration of the mover 12. As shown in FIG. At both ends of the vibration range, the speed of the mover 12 instantaneously becomes zero and the direction of movement is switched. In the electromagnetic suspension, the control at the moment of switching the biasing direction is emphasized. Therefore, if the thrust characteristics change sharply before and after the timing of switching the biasing direction, it becomes complicated to appropriately control the electromagnetic suspension.

In general, an electromagnetic suspension or the like is designed to allow an error of about ±20% in thrust or the like in order to ensure versatility. For example, even if the temperature of the linear motor is 20° C. when the linear motor starts to be used, the temperature may rise to about 80° C. due to heat generation such as copper loss when the linear motor is used for a long time. When the winding material is copper, the resistance at 80°C is about 1.23 ((234.5+80)/(234.5+20) compared to the resistance at 20°C. = 1.23). Therefore, as described above, the linear motors 10, 10A, and 10B are often designed taking into consideration the likelihood of about ±20% with respect to assumed disturbance factors. Also, when the cost and accuracy of the linear motor are important, it may be preferable to set the likelihood to be small, such as about ±10%.

In FIG. 7, the thrust force characteristic Q of the linear motor 10 of the present embodiment has no sharp change in the thrust force FC, and achieves a thrust force equal to or greater than the target thrust force FC1 over the entire normal use range. Further, in the thrust force characteristic QA by the linear motor 10A of the modified example, there is no sharp change in the thrust force FC, but the thrust force FC is slightly below the target thrust force FC1 when the position of the mover 12 is near 100%. However, since this error is within the range of ±20%, it is considered that the linear motor 10A can be controlled similarly to the linear motor 10 of this embodiment.

On the other hand, the thrust characteristic QB by the linear motor 10B of another modified example has a sudden change, and the thrust near both ends of the normal range is 20% or more lower than the target thrust. Therefore, the control of the linear motor 10B of the modified example may be slightly more complicated than the linear motor 10 of the present embodiment. However, even the linear motor 10B having the thrust characteristic QB is sufficiently practical in applications where linearity is not required so much. Even if the magnetic tooth pitch TP>the magnet length ML or the magnetic tooth width TL<the normal range length UL, if it is possible to keep the thrust FC within the range of FC1±ΔFC with respect to the target thrust FC1, As a linear motor for an electromagnetic suspension, practicality can be further enhanced.

According to FIG. 7, like the linear motor 10B in FIG. 6, it is preferable to set the magnet length ML of the magnet 124 to 0.8 times or more the magnetic tooth pitch TP. Further, if the magnet length ML of the magnet 124 is set to 0.9 times or more the magnetic tooth pitch TP (not shown), the shape of the thrust characteristic becomes even more flat, which is more preferable. Furthermore, as in the linear motor 10A of FIG. 6, if the magnet length ML of the magnet 124 is substantially the same as the magnetic tooth pitch TP, the shape of the thrust characteristic becomes even more flat, which is more preferable. Furthermore, as in the linear motor 10 of the present embodiment, if the magnet length ML of the magnet 124 is made larger than the magnetic tooth pitch TP, the shape of the thrust characteristics becomes even more flat, which is even more preferable.

FIG. 8 is a schematic diagram of the linear motor 10A of the modified example described above and the linear motor 10C of another modified example. In another modified linear motor 10C, the magnetic tooth width TL of the magnetic teeth 151 to 154 is narrower than that of the linear motor 10A. Other configurations of the linear motor 10C are similar to those of the linear motor 10A. In the illustrated state, the mover 12 of the linear motor 10A is positioned at the left end of the normal range, as in FIG. Further, the position of the mover 12 of the linear motor 10C of the modified example is the same as that of the mover 12 of the linear motor 10A.

Both the linear motors 10A and 10C have the same magnet length ML and magnetic tooth pitch TP. However, in the linear motor 10C of the modified example, the magnetic tooth width TL is shorter than the normal range length UL. Therefore, the magnet 124 of the linear motor 10C does not face the magnetic teeth 152, 154 in the illustrated state. Then, the thrust applied to the magnet 124 by the magnetic teeth 152 and 154 is reduced, so the thrust applied to the mover 12 is also reduced.

In the example shown in FIG. 8, the position of the mover 12 is near -100% (see FIG. 7), but the same is true even if the position of the mover 12 is near 100% on the opposite side (see FIG. 7). thrust decreases. Therefore, in order to suppress fluctuations in thrust accompanying movement of the mover 12, it is desirable that all the magnetic teeth 151 to 154 and the magnet 124 are always close to each other within a normal range. Furthermore, it is most desirable that all the magnetic teeth 151-154 and the magnet 124 always face each other within the range of normal use.

<Effect of the first embodiment>
As described above, according to the linear motor (10) of the present embodiment, the armature core (11a) includes the first magnetic teeth (151) facing the first surface (122f) and the first surface ( 122f) and adjacent to the first magnetic tooth (151) along the movement direction (z-axis direction), and a third magnetic tooth (152) facing the second surface (122r). and a fourth magnetic tooth (154) facing the second surface (122r) and adjacent to the third magnetic tooth (153) along the movement direction (z-axis direction); , and the mover (12) defines the distance in the moving direction (z-axis direction) between the center of the first magnetic tooth (151) and the center of the second magnetic tooth (152) as the magnetic tooth pitch (TP) , the first surface (122f) is magnetized to either the S pole or the N pole over a section longer than 0.8 times the magnetic tooth pitch (TP) along the moving direction, The second surface (122r) is magnetized to the other pole, S pole or N pole, over a section longer than 0.8 times the magnetic tooth pitch (TP) along the movement direction.

As a result, the linear motor (10) can be realized with a small number of parts, and the linear motor (10) can be constructed at low cost.
More specifically, according to this embodiment, the amount of magnets (124) used in the linear motor (10) can be reduced, and the linear motor (10) has a substantially constant amount of power regardless of the position of the mover (12). of thrust can be generated. As a result, the weight of the mover (12) is lightened, the response is improved, and the controllability is improved. Furthermore, cost reduction is possible by reducing the number of magnets. Moreover, it is sufficient to set one magnet (124) in the mover (12), and workability can be improved.

In addition, the mover (12) has an S pole surface (124S ) and a north pole face (124N) magnetized to the north pole over a distance (ML) longer than 0.8 times the magnetic tooth pitch (TP); and a frame (122) made of a material having a lower magnetic permeability than the magnet (124) and holding the magnet (124).
Thus, by attaching the magnet (124) to the frame (122), the mover (12) can be configured, and the linear motor (10) can be configured at a lower cost.

Further, in the present embodiment, the first position (state P2), and the second position (state P3) is the position in which the other end (124b) of the magnet (124) reaches the outer end (152b) of the second magnetic tooth (152) in the moving direction (z-axis direction). Then, the width (TL) of each of the first to fourth magnetic teeth (151 to 154) is the width of the mover (12) from the first position (state P2) to the second position (state P3). longer than the range length (UL), which is the distance traveled.
This allows the linear motor (10) to generate substantially constant thrust regardless of the position of the mover (12).

In addition, the frame (122) has a through hole (122h) through which the first surface (122f) and the second surface (122r) are inserted. ).
Thus, by mounting the magnet (124) in the through hole (122h), the mover (12) can be configured, and the linear motor (10) can be configured at a lower cost.

The magnet (124) is a samarium-iron-nitrogen based magnet. As a result, the magnets (124) can be kneaded into resin and molded, and the linear motor (10) can be constructed at a lower cost.

Also, the magnet (124) has a rectangular plate-like or rectangular parallelepiped shape.
As a result, the shape of the magnet (124) can be simplified, and the linear motor (10) can be constructed at a lower cost. Furthermore, by forming the magnet (124) into a rectangular plate shape, the magnetic pole area can be increased while reducing the amount of magnet used.

Moreover, according to this embodiment, the magnet (124) can be prevented from being exposed outside the stator (11) in the normal use range shown in FIG. Furthermore, the magnet (124) can always be opposed to any one of the first to fourth magnetic teeth (151 to 154) and the commutating pole teeth 162 and 164 in the normal range. This makes it very unlikely that the magnet (124) will be left without an opposing magnetic object. Therefore, according to this embodiment, the permeance coefficient can be improved, and the robustness of the demagnetization resistance can be enhanced.

[Second embodiment]
<Configuration of Second Embodiment>
FIG. 9 is a perspective view of an electromagnetic suspension 100 according to a second embodiment of the invention. In addition, in the following description, the same code|symbol may be attached|subjected to the part corresponding to each part of 1st Embodiment mentioned above, and the description may be abbreviate|omitted.
The electromagnetic suspension 100 includes the linear motor 10 and the elastic body 20 according to the first embodiment. One end of the mover 12 of the linear motor 10 is connected to a damping object. Here, the object to be damped is an object whose vibration is to be suppressed by the electromagnetic suspension 100. In the illustrated example, the object to be damped is the outer tub 37 of the washing machine W (see FIG. 10).

Also, the other end of the mover 12 is fixed to a fixing jig J. As shown in FIG. Further, the movement of the stator 11 of the linear motor 10 is restricted by another fixture (not shown). Therefore, when the outer tub 37 of the washing machine vibrates in the z-axis direction, the movable element 12 reciprocates along the z-axis direction, and the relative positional relationship between the movable element 12 and the stator 11 changes.

In addition, in this embodiment, a coil spring made of metal is used as the elastic body 20 . Here, the elastic body 20 applies elastic force to the stator 11 and is interposed between the stator 11 and the fixing jig J. As shown in FIG. As shown in FIG. 9, the mover 12 penetrates the stator 11 and also penetrates the elastic body 20 .

The elastic body 20 has a spring force capable of holding the outer tub 37 at a predetermined position in the washing machine even when the linear motor 10 is not energized. As a result, even if the mover 12 nearly penetrates upward in the z-axis due to a control error, the weight of the outer tank 37 and the spring force of the elastic body 20 will push back the mover 12 . Similarly, when the mover 12 is about to penetrate downward in the z-axis, the spring force of the elastic body 20 pushes it back. That is, the elastic body 20 ensures the fail-safe property of control, and the robustness can be enhanced without arranging members such as stoppers at both ends of the mover 12 .

<Effect of Second Embodiment>
As described above, the electromagnetic suspension (100) of this embodiment urges the linear motor (10) and the stator (11) or mover (12) in the moving direction (z-axis direction) according to the first embodiment. and an elastic body (20) for In particular, the elastic body (20) comprises a coil spring made of metal.
As a result, even when the linear motor (10) is not energized, the linear motor (10) can be held at a predetermined position, and even when the linear motor (10) is operating, the mover (12) is prevented from passing through. can be done.

[Third embodiment]
<Configuration of the third embodiment>
(overall structure)
FIG. 10 is a perspective view of a washing machine W according to a third embodiment of the invention.
A washing machine W shown in FIG. 10 is a drum-type washing machine and also has a function of drying clothes. The washing machine W includes a base 31, a housing 32, a door 33, an operation/display panel 34, an outer tub 37, a pair of electromagnetic suspensions 100L and 100R, and a drain hose H. Here, the electromagnetic suspensions 100L and 100R are configured similarly to the electromagnetic suspension 100 in the second embodiment.

The housing 32 includes left and right side plates 32a, 32a, a front cover 32b, a rear cover 32c (see FIG. 11), and a top cover 32d. The base 31 supports the housing 32 . A circular slot h1 (see FIG. 11) for loading and unloading clothes is formed near the center of the front cover 32b.
A door 33 is an openable and closable lid provided at the input port h1.

11 is a longitudinal sectional view of the washing machine W. FIG.
The washing machine W includes a washing tub 35, a lifter 36, a drive mechanism 38, and a blower unit 39 in addition to the above-described configuration. The washing tub 35 accommodates clothes and has a cylindrical shape with a bottom. The washing tub 35 is contained in an outer tub 37 and is rotatably supported coaxially with the outer tub 37 . The peripheral wall and the bottom wall of the washing tub 35 are provided with a large number of through holes (not shown) for water and ventilation. The opening h2 of the washing tub 35 and the opening h3 of the outer tub 37 face the door 33 in the closed state.

In addition, in the example shown in FIG. 11, the central axis of rotation of the washing tub 35 is inclined so that the opening side is higher, but the present invention is not limited to this. That is, the central axis of rotation of washing tub 35 may be horizontal or vertical. The lifter 36 lifts and drops the clothes during washing and drying, and is installed on the inner peripheral wall of the washing tub 35 . The outer tub 37 stores washing water and the like, and has a cylindrical shape with a bottom. As shown in FIG. 11 , the outer tub 37 contains the washing tub 35 .

Further, as shown in FIG. 10, the electromagnetic suspensions 100L and 100R are arranged on the left and right sides of the outer tank 37, but only the left electromagnetic suspension 100L is shown in FIG. A drain hole (not shown) is provided at the lowest portion of the bottom wall of the outer tank 37, and a drain hose H is connected to this drain hole. Washing water is stored in the outer tub 37 while a drain valve (not shown) provided on the drain hose H is closed, and the washing water is discharged by opening the drain valve. It's like

The drive mechanism 38 is a mechanism for rotating the washing tub 35 and is installed outside the bottom wall of the outer tub 37 . A rotating shaft of a motor 38 b (see FIG. 13 ) provided in the drive mechanism 38 passes through the bottom wall of the outer tub 37 and is connected to the bottom wall of the washing tub 35 . The blower unit 39 is for sending hot air into the washing tub 35 and is arranged above the washing tub 35 . The blower unit 39 includes a heater (not shown) and a fan (not shown). Then, the air heated by the heater is sent into the washing tub 35 by the fan. As a result, the wet clothes are gradually dried in the washing tub 35 .

Here, the vibration of the outer tub 37, that is, the vibration of the washing machine W will be briefly described. During washing, rinsing, and drying, the drive mechanism 38 shown in FIG. 11 rotates the washing tub 35 at a low speed, and the lifter 36 lifts and drops the clothes accumulated at the bottom of the washing tub 35, repeating the tumbling action. Further, during dehydration, the washing tub 35 rotates at high speed, and centrifugal dehydration is performed in which the moisture of the clothes is pushed out by the centrifugal force generated by the rotation.

In the conventional washing machine, during washing, rinsing, and drying, the amplitude of the vibration of the washing tub 35 often increases due to the reaction force of the falling clothes. In addition, in conventional washing machines, vibration and noise often occur in the washing machine W due to the uneven position of the clothes during dehydration. In this manner, the manner of vibration of the washing machine W changes from moment to moment depending on various conditions such as washing, rinsing, drying, dehydration, etc. in addition to the amount and position of the clothes in the washing tub 35, moisture content, and the like. The vibration propagates to the outer tub 37 .

(Configuration of damping device 200)
FIG. 12 is a configuration diagram of a vibration damping device 200 applied to this embodiment.
12, the vibration damping device 200 includes an inverter 40, a current detector 50, a thrust adjustment section 60, a rectifier circuit 70, and left and right electromagnetic suspensions 100L and 100R. The damping device 200 suppresses the vibration of the object G to be damped. In this embodiment, the damping object G is the outer tub 37 of the washing machine W (see FIG. 11).

In FIG. 12, the left and right electromagnetic suspensions 100L and 100R are represented by one frame. Also, the linear motors 10 included in the electromagnetic suspensions 100L and 100R are called linear motors 10L and 10R, respectively. Similarly, the elastic bodies 20 included in the electromagnetic suspensions 100L and 100R are called elastic bodies 20L and 20R.

The rectifier circuit 70 rectifies the AC voltage applied by the AC power supply E and applies the DC voltage to the inverter 40 . It should be noted that the AC power supply E and the rectifier circuit 70 may be considered together as a DC power supply. Inverter 40 converts the DC voltage applied from rectifier circuit 70 into a single-phase AC voltage based on voltage command V* from thrust adjustment unit 60, and this single-phase AC voltage is applied to the windings of linear motors 10L and 10R. 11b (see FIG. 2). In other words, inverter 40 has a function of driving linear motors 10L and 10R based on voltage command V*.

FIG. 13 is a configuration diagram of a main part of the vibration damping device 200. As shown in FIG. The rectifier circuit 70 is a well-known voltage doubler rectifier circuit that converts an AC voltage applied from the AC power supply E into a DC voltage. As shown in FIG. 13, the rectifier circuit 70 includes a diode bridge circuit 72 formed by bridge-connecting diodes D1 to D4, and two smoothing capacitors 74 and 76 connected in series. Further, the drive mechanism 38 shown in FIG. 11 includes an inverter 38a and a motor 38b, as shown in FIG.

The voltage (DC voltage including pulsating current) generated by the diode bridge circuit 72 is smoothed by the smoothing capacitors 74 and 76 to generate a DC voltage approximately twice the voltage of the AC power supply E. The rectifying circuit 70 is connected to the inverter 40 via a positive wire k1 and a negative wire k2, and is also connected to the inverter 38a of the driving mechanism 38 that rotates the washing tub 35 (see FIG. 11). there is

The inverter 40 converts the DC voltage applied from the rectifier circuit 70 into two systems of single-phase AC voltages, and applies these two systems of single-phase AC voltages to the windings 11b (see FIG. 2) of the linear motors 10L and 10R, respectively. It is an inverter to apply.
As shown in FIG. 13, the inverter 40 includes a first leg including switching elements SW1 and SW2, a second leg including switching elements SW3 and SW4, and a third leg including switching elements SW5 and SW6. are connected in parallel. IGBTs (Insulated Gate Bipolar Transistors), for example, can be used as these switching elements SW1 to SW6. A free wheel diode D is connected in antiparallel to each of the switching elements SW1 to SW6.

A connection point of the switching elements SW1 and SW2 is connected to the winding 11b (see FIG. 2) of the linear motor 10L through the wiring k3. That is, the leg corresponding to one phase of the three-phase inverter 40 is connected to the left linear motor 10L. A connection point of the switching elements SW5 and SW6 is connected to the winding 11b (see FIG. 2) of the linear motor 10R through the wiring k5. That is, another leg corresponding to one phase of the three-phase inverter 40 is connected to the right linear motor 10L.

The connection point of the switching elements SW3 and SW4 is connected to the winding 11b (see FIG. 2) of the linear motor 10L via the wiring k4, and is also connected to the winding 11b of the linear motor 10R via the wiring k4. It is connected. That is, the remaining legs of the three-phase inverter 40 are connected to the left and right linear motors 10L and 10R.

Thus, the cost of the inverter 40 can be reduced by sharing the left and right as one inverter 40 instead of separately providing inverters corresponding to the left and right linear motors 10L and 10R. By controlling the on/off of the switching elements SW1 to SW6 based on PWM (Pulse Width Modulation) control, a single-phase AC voltage is applied to the windings 11b (see FIG. 2) of the linear motors 10L and 10R. It has become so.
The current detector 50 detects the current flowing through the linear motors 10L and 10R, and is inserted in the wiring k4. That is, the current detector 50 detects the current flowing through the windings 11b (see FIG. 2) of the linear motors 10L and 10R.

(Thrust adjustment unit 60)
Although not shown, the thrust adjustment unit 60 shown in FIG. 12 includes electronic circuits such as a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and various interfaces. . Then, the program stored in the ROM is read out and developed in the RAM, and the CPU executes various processes.

In FIG. 12, the thrust adjusting section 60 has a function of adjusting the thrust of the linear motors 10L and 10R by driving the inverter 40 based on the current i detected by the current detector 50. FIG. That is, the thrust adjustment unit 60 detects the polarity of the current i flowing through the current detector 50 during the dead time of the inverter 40 . The polarity of the current i indicates the moving direction of the linear motors 10L and 10R.

Therefore, the thrust force adjustment unit 60 generates a voltage command V* for suppressing the movement of the linear motors 10L and 10R, and switches ON/OFF of the switching elements SW1 to SW6 based on this voltage command V*. As a result, when the relative position between the mover 12 and the stator 11 changes due to the vibration of the outer tank 37 (see FIG. 11), the thrust adjusting unit 60 adjusts the thrust of the linear motors 10L and 10R so as to cancel this change. has a function to adjust

<Effect of the third embodiment>
As described above, the washing machine (W) of the present embodiment includes the electromagnetic suspensions (100L, 100R) according to the second embodiment, the inverter (40) that supplies alternating current to the armature winding (11b), the electric A current detector (50) that detects the current flowing through the child winding (11b), and the thrust of the linear motor (10) by controlling the inverter (40) based on the current detected by the current detector (50). and a thrust adjustment unit (60) that adjusts the
As a result, the current detector (50) can detect the current flowing through the armature winding (11b), and the linear motor ( 10) thrust can be adjusted.

Furthermore, the washing machine (W) of the present embodiment includes a washing tub (35) containing clothes, an outer tub (37) containing the washing tub (35), and a driving mechanism (38) for rotating the washing tub. , and the electromagnetic suspensions (100L, 100R) suppress the vibration of the outer tank (37).
Thus, according to the present embodiment, vibration of the outer tub (37) can be suppressed with a relatively simple configuration. Moreover, according to this embodiment, since it is not necessary to provide a position sensor for detecting the position of the mover (12), the cost of the washing machine (W) can be reduced. Further, since the stator (11) and mover (12), which are the components of the linear motors (10L, 10R), are hardly damaged or worn, the durability of the electromagnetic suspensions (100L, 100R) can be increased. can.

Further, according to this embodiment, the single-phase AC voltage applied to the left and right linear motors (10L, 10R) can be generated by one inverter 40 having six switching elements. If separate inverters are provided for the left and right linear motors (10L, 10R), eight switching elements are required. Therefore, according to this embodiment, the cost of the washing machine (W) can be reduced as compared with a configuration in which separate inverters are provided corresponding to the left and right linear motors (10L, 10R).

[Fourth Embodiment]
Next, a washing machine according to a fourth embodiment of the present invention will be described. The configuration and operation of the washing machine of the fourth embodiment are the same as those of the third embodiment (see FIGS. 10 to 13).
However, in this embodiment, the thrust force adjustment unit 60 (see FIG. 12) detects the vibration frequency of the left and right linear motors 10L and 10R based on the output signal of the current detector 50, and adjusts the inverter 40 according to the vibration frequency. The difference is that the output current is changed.

First, in the third embodiment described above, the output current of the inverter 40 is not changed based on the vibration frequencies of the linear motors 10L and 10R. That is, when the linear motors 10L and 10R are considered as "dampers", the viscous damping coefficient C [Ns/m] of the dampers is constant regardless of the vibration frequency in the third embodiment. On the other hand, in this embodiment, the viscous damping coefficient C [Ns/m] is changed according to the vibration frequency of the linear motors 10L and 10R. Details thereof will be described below.

The equation of motion of the electromagnetic suspension 100, which is an electromagnetic suspension, is represented by the following equation (1). Note that F _D [N] shown in Equation (1) is the force generated by the electromagnetic suspension 100 (that is, the thrust force of the linear motor 10). Also, x[m] is the position of the mover 12 .

Also, the equation of motion of the thrust of the linear motor 10 is represented by the following equation (2). Note that _FL [N] is the thrust force of the linear motor 10 and K _e [N/A] is the motor constant of the linear motor 10 . I[A] is the current flowing through the winding 11b (see FIG. 2), and V[V] is the voltage applied to the winding 11b. Also, R [Ω] is the resistance of the winding 11b, and φ [T] is the magnetic flux generated in the winding 11b.

Here, since the force F _D in the formula (1) and the thrust _FL in the formula (2) are equivalent, the following formula (3) is derived. Note that C [N·m/s] is the viscous damping coefficient of the linear motor 10 .

FIG. 14 shows experimental results showing changes in the rotational speed of the washing tub 35 and the displacement (vibration) of the outer tub 37 in a comparative example using an oil damper with a constant viscous damping coefficient C. FIG. The x-axis indicates the range of the rotation speed of the washing machine W from zero to the maximum rotation speed in percent. The y-axis indicates the displacement (vibration) of the outer tub 37 as a relative value when the rotation speed is zero.
In the experiment shown in FIG. 14, the washing tub 35 was rotated with 1 kg of clothes placed at a predetermined uneven position in the washing tub 35 (the same applies to FIG. 15, which will be described later).

As shown in FIG. 14, in the configuration of the comparative example, the amplitude of the outer tub 37 changes as the rotation speed of the washing tub 35 increases. Specifically, when the rotation speed of the washing tub 35 is increased from zero, the amplitude of the outer tub 37 once decreases at a rotation speed of about 5 [%], and the amplitude of the outer tub 37 at a rotation speed of about 10 [%]. The amplitude suddenly increases and reaches the maximum amplitude. In addition, the amplitude of the outer tub 37 increases at a rotation speed of 10 to 17 [%], and in the region of 20 [%] or more, as the rotation speed of the washing tub 35 increases, the amplitude of the outer tub 37 decreases. there is

FIG. 15 shows experimental results showing changes in the rotational speed of the washing tub 35 and the displacement (vibration) of the outer tub 37 in the fourth embodiment. In the experiment in FIG. 15, the duty ratio of the inverter 40 was adjusted so that the higher the rotation speed of the washing tub 35 (that is, the higher the vibration frequency f of the outer tub 37), the smaller the viscous damping coefficient C of the linear motor 10. controlled.

As shown in FIG. 15, the maximum amplitude of the outer tub 37 when the rotation speed of the washing tub 35 is approximately 10 [%] is approximately 5 mm, and the maximum amplitude (approximately 10 [PU]) of the comparative example shown in FIG. is about half of Further, in a region where the rotation speed of the washing tub 35 is 50% or higher, the amplitude of the outer tub 37 is approximately 1 [PU]. Thus, according to the fourth embodiment, by variably controlling the viscous damping coefficient C, the vibration of the outer tub 37 can be suppressed more effectively than in the third embodiment.

[Modification]
The present invention is not limited to the embodiments described above, and various modifications are possible. The above-described embodiments are illustrated for easy understanding of the present invention, and are not necessarily limited to those having all the described configurations. Also, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Also, it is possible to delete part of the configuration of each embodiment, or to add or replace other configurations. Also, the control lines and information lines shown in the drawings are those considered to be necessary for explanation, and do not necessarily show all the control lines and information lines necessary on the product. In practice, it may be considered that almost all configurations are interconnected. Possible modifications to the above embodiment are, for example, the following.

(1) In each of the above-described embodiments, as shown in FIG. 4, one rectangular plate-shaped magnet 124 is fitted into one rectangular plate-shaped frame 122 to configure the mover 12 . However, one frame 122 may be equipped with a plurality of magnets. Also, a plurality of magnets may be attached to each of a plurality of frames. Further, the shapes of the frame 122 and the magnets 124 are not limited to rectangular plate shapes, and various shapes can be adopted.

(2) In FIG. 5, the magnetization directions of the S pole and N pole of the magnet 124 and the magnetic teeth 151 to 154 may be reversed.

(3) In addition, in the third and fourth embodiments, the electromagnetic suspension 100 is applied to damping the washing machine W, but the electromagnetic suspension 100 can , railway vehicles, automobiles, and the like.

(4) In each of the above-described embodiments, the linear motor 10 is driven with a single-phase alternating current, but the linear motor 10 may be driven with, for example, a three-phase alternating current.

10, 10A, 10B, 10C, 10L, 10R Linear motor 11 Stator 11a Core (armature core)
11b winding (armature winding)
12 Mover 20, 20L, 20R Elastic body 35 Washing tub 37 Outer tub 38 Drive mechanism 40 Inverter 50 Current detector 60 Thrust adjustment unit 100, 100L, 100R Electromagnetic suspension 122 Frame 122f Surface (first surface)
122h through-hole 122r rear surface (second surface)
124 magnet 124a left end (one end)
124b right end (other end)
124N N pole surface 124S S pole surface 151a Left end (outer end)
152b Right end (outer end)
151 magnetic tooth (first magnetic tooth)
152 magnetic tooth (second magnetic tooth)
153 magnetic tooth (third magnetic tooth)
154 magnetic tooth (fourth magnetic tooth)
P2 state (first position)
P3 state (second position)
TL Magnetic face width (width)
TP Magnetic tooth pitch UL Normal range length (range length)
W Washing machine z z-axis direction (moving direction)

Claims (8)

a stator having an armature core and an armature winding;
a mover having a first surface and a second surface facing the stator and moving relative to the stator along a predetermined movement direction;
The armature core includes a first magnetic tooth facing the first surface and a second magnetic tooth facing the first surface and adjacent to the first magnetic tooth along the movement direction. a tooth, a third magnetic tooth opposite the second surface, and a fourth magnetic tooth opposite the second surface and adjacent to the third magnetic tooth along the direction of movement; with
When the distance in the direction of movement between the center of the first magnetic tooth and the center of the second magnetic tooth is defined as the magnetic tooth pitch, the movable element has a magnetic tooth pitch of 0.00 of the magnetic tooth pitch along the movement direction. The first surface is magnetized to one of the south or north poles over an interval longer than 8 times the magnetic tooth pitch along the direction of movement. across, said second face is magnetized to the other of a south pole or a north pole;
The mover is
An S pole surface magnetized to the S pole over a distance longer than 0.8 times the magnetic tooth pitch along the movement direction, and an N pole surface magnetized to the S pole over a distance longer than 0.8 times the magnetic tooth pitch a plate-shaped magnet having a north pole face magnetized to
a frame that is formed of a material having a lower magnetic permeability than the magnet and holds the magnet,
A position where one end of the magnet in the moving direction reaches the outer end of the first magnetic tooth is defined as a first position, and a position where the other end of the magnet in the moving direction reaches the outer end of the second magnetic tooth. is the second position, the width of each of the first to fourth magnetic teeth is longer than the range length, which is the moving distance of the mover from the first position to the second position
A linear motor characterized by: the frame has a through-hole passing through the first surface and the second surface;
The linear motor according to claim 1, wherein the magnet is integrally formed and mounted in the through hole. 3. The linear motor according to claim 2 , wherein the magnet is a samarium-iron-nitrogen system magnet. The linear motor according to claim 3 , wherein the magnet has a rectangular plate shape or a cuboid shape. a linear motor according to any one of claims 1 to 4 ;
and an elastic body that biases the stator or the mover in the movement direction. The electromagnetic suspension according to claim 5 , wherein the elastic body includes a coil spring made of metal. an inverter that supplies alternating current to the armature winding;
a current detector that detects a current flowing through the armature winding;
7. The electromagnetic suspension according to claim 6 , further comprising a thrust adjusting section that adjusts the thrust of the linear motor by controlling the inverter based on the current detected by the current detector. an electromagnetic suspension according to claim 7 ;
a washing tub for storing clothes;
an outer tub containing the washing tub;
a driving mechanism for rotating the washing tub;
, wherein the electromagnetic suspension suppresses vibration of the outer tub.

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