JP2023117963A - Linear motor, electromagnetic suspension, and washing machine - Google Patents

Abstract

To provide a linear motor that suppresses an eddy current generated in a mover frame of a linear motor and prevents damage when a magnet is inserted.SOLUTION: In a linear motor including a stator having an armature core and an armature winding, a plurality of permanent magnets 124 having a first surface (front surface 124f) and a second surface (back surface 124r) facing the stator, and a mover 12 that moves relative to the stator, the mover 12 includes a frame portion 121 and a plurality of bar portions 122, and the plurality of permanent magnets 124 and the plurality of bar portions 122 are inserted and fixed along groove portions 121b provided inside the frame portion 121, and the frame portion 121 and the bar portion 122 are in contact with each other at contact surface 122c, and the bar portion 122 is provided between the permanent magnets 124.SELECTED DRAWING: Figure 3

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 motors for linear motion. 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 describes a technique of applying an electromagnetic suspension having a linear motor as a suspension for a washing machine. In Patent Document 1, a mover is configured by fitting a magnet into a rectangular plate-shaped frame. On the other hand, in Patent Document 2, a magnet piece is attached to a cylindrical magnet holding frame that is open at one end in the axial direction, and a ring-shaped holder is attached to the open end.

Japanese Patent Application Laid-Open No. 2021-85442 JP-A-2000-228855

In the linear motor disclosed in Patent Document 1, a rectangular plate-shaped frame of the mover is provided with a rectangular hole, and the outer periphery of the frame is integrally formed. If the frame is a metal frame, since there are armature single poles on the upper and lower sides of the frame, there is a risk that alternating magnetic fields will interlink in the loops on the outer circumference of the frame and a large eddy current will be generated on the outer circumference of the frame.

As a countermeasure against eddy currents flowing in the frame, in Patent Document 2, the frame (magnet holding frame) is divided, and a ring-shaped holder is attached after the magnet is inserted. However, after inserting the first magnet, when inserting a second magnet having a polarity different from that of the first magnet, a strong magnetic attraction force acts between the magnets, and there is a risk of damage due to collision.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a linear motor that suppresses eddy currents generated in the mover frame of the linear motor and prevents damage during insertion of magnets.

In order to achieve the above object, a linear motor of the present invention comprises a stator having an armature core and armature windings, and a first surface and a second surface facing the stator. A linear motor comprising a mover that has a plurality of permanent magnets and moves relative to the stator, wherein the mover includes a frame portion and a plurality of bar portions, and the plurality of and the plurality of bar portions are inserted and fixed along a groove provided inside the frame portion so that the frame portion and the bar portion are in contact with each other at the contact surface, and the plurality of permanent magnets The bar portion is provided between the magnets. Other aspects of the present invention are described in embodiments below.

According to the present invention, eddy currents generated in the mover frame of a linear motor can be suppressed, and damage during magnet insertion can be prevented.

1 is a perspective view of an electromagnetic suspension according to a first embodiment; FIG. 1 is a perspective sectional view of a linear motor according to a first embodiment; FIG. 3 is an exploded perspective view of the mover according to the first embodiment; FIG. It is a perspective view of a mover of a linear motor of a comparative example. It is a comparison of the inductance of 1st Embodiment and a comparative example. FIG. 5 is an explanatory diagram of a mover of a comparative example; It is explanatory drawing of the mover of 1st Embodiment. FIG. 11 is a cross-sectional view perpendicular to the z-axis direction of the mover according to the second embodiment; It is the figure seen from the y-axis direction of the movable child which concerns on 3rd Embodiment. It is a thrust waveform when a direct current is applied to the windings of the linear motor according to the third embodiment, and the mover is moved ±25 mm in the z-axis direction. It is the figure seen from the y-axis direction of the mover concerning 4th Embodiment. It is a thrust waveform when a direct current is applied to the windings of the linear motor according to the fourth embodiment, and the mover is moved ±25 mm in the z-axis direction. It is a perspective view of the electromagnetic suspension which concerns on 5th Embodiment. It is a perspective view of the washing machine which concerns on 6th Embodiment. It is a longitudinal section of the washing machine concerning a 6th embodiment. It is a lineblock diagram of a damping device applied to a 6th embodiment. It is a block diagram which shows the principal part of a damping device. It is an experimental result showing changes in the rotational speed of the washing tub and the displacement (vibration) of the washing machine W in Comparative Example 1 using an oil damper with a constant viscous damping coefficient. It is an experimental result which shows the change of the rotation speed of a washing tub, and the displacement (vibration) of a washing machine in the state which applied the electromagnetic suspension of a comparative example to 7th Embodiment. It is an experiment result which shows the change of the rotation speed of a washing tub, and the displacement (vibration) of a washing machine in the state which applied the electromagnetic suspension in 5th Embodiment to 7th Embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In a plurality of embodiments and modified examples of each embodiment, the same constituent elements are denoted by the same reference numerals, and descriptions thereof are omitted.
<First Embodiment>
A linear motor according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 7. FIG. FIG. 1 is a perspective view of an electromagnetic suspension according to the first embodiment. The linear motor 10 is applied, for example, to an electromagnetic suspension 100 (see FIG. 13) of another embodiment described later, and the electromagnetic suspension 100 is applied, for example, to suppress vibration of the washing machine W (see FIG. 14). be.

As indicated by symbols x, y, and z in FIG. 1, the x-axis, y-axis, and z-axis are determined (the z-axis is the traveling direction of the linear motor). FIG. 1 illustrates the appearance of an electromagnetic suspension 100. As shown in FIG. Electromagnetic suspension 100 includes linear motor 10 .

[Structure of Electromagnetic Suspension 100]

The electromagnetic suspension 100 is fixed between a pair of opposed shafts 21 connecting between the shaft fixing metal fittings 23 (fixing metal fittings), a stator 11 having an armature core and an armature winding, and the shaft fixing metal fittings 23, and is fixed. A magnet or magnetic body having a first surface (e.g., front surface 124f in FIG. 3) facing child 11 and a second surface (e.g., rear surface 124r in FIG. and an elastic body 20 mounted on the shaft and contracted between one of the shaft fixing metal fittings 23 and the arm portion 111 of the stator 11 .

Two shafts 21 and two elastic bodies 20 are positioned parallel to the mover 12 of the linear motor 10 and the propelling direction (the z-axis direction in the drawing). The shaft 21 penetrates the elastic body 20 . Further, the shaft 21 slides in the moving direction of the mover 12 via the stator 11 of the linear motor 10 and a bearing (not shown). In this embodiment, as the bearing, a sliding bearing having a resin surface lubricated is used.

[Configuration of linear motor 10]
FIG. 2 is a perspective sectional view of the linear motor 10 according to the first embodiment. FIG. 2 shows a bird's-eye view of the appearance of the linear motor 10, and cuts a half of it to show the internal structure. The linear motor 10 includes a stator 11, which is an armature, and a plate-shaped mover 12 extending in the z-axis direction.

The stator 11 is formed in a substantially prismatic shape extending in the z-axis direction, and a rectangular plate-shaped mover 12 is loosely inserted in the hollow portion of the stator 11 . 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 applying the linear motor 10 to the electromagnetic suspension 100, the stator 11 or the mover 12 is coupled to the damping object Dt (see FIG. 13). In the example shown in FIG. 1, outer tub 37 (see FIG. 15) of washing machine W is damping object Dt, and stator 11 or mover 12 is coupled to outer tub 37 . Here, the outer tub 37 of the washing machine W is described as the damping object Dt, but the connection destination is changed if the structure of the washing machine is changed. In other words, it may be arbitrarily connected to the components of the washing machine W so as to enhance the damping effect of the washing machine W.

The stator 11 includes a core 11a (armature core) and windings 11b (armature winding). The core 11a is made by laminating electromagnetic steel sheets in the z-axis direction and is integrated by caulking or welding. The core 11a also has teeth 11a2 that protrude toward the mover 12. As shown in FIG. The winding 11b is wound around these teeth 11a2. A known insulating treatment such as a bobbin 11b2 (or insulating resin/insulating paper) is applied between the winding 11b and the tooth portion 11a2.

[Configuration of mover 12]
FIG. 3 is an exploded perspective view of the mover 12 according to the first embodiment. The mover 12 includes a frame portion 121 made of a nonmagnetic material, a bar portion 122 made of a nonmagnetic material, and permanent magnets 124a and 124b having different polarities. The frame portion 121 has a pair of frame arm portions 121a extending in the z-axis direction, and groove portions 121b are provided along the z-axis direction on the mutually facing surfaces of the frame arm portions 121a. In the frame portion 121, these parts are inserted in the order of the permanent magnet 124a, the bar portion 122, the permanent magnet 124b, and the bar portion 122 in the groove portion 121b. The bar portion 122 has contact surfaces 122c (contact portions) that contact the frame portion 121 at both ends in the longitudinal direction (x-axis direction). The contact surface 122c is a portion that makes surface contact with a predetermined portion of the frame portion 121 . Most of the contact surface 122c may be out of contact with the frame portion 121 .

[Configuration of mover of comparative example]
FIG. 4 is a perspective view of a mover of a linear motor of a comparative example. The mover 12 of the linear motor of the comparative example is formed of a non-magnetic material in a rectangular frame shape, and includes a frame 121 having two through holes (windows into which permanent magnets are fitted) and permanent magnets 124a and 124b having different polarities. and two through holes (windows) are fitted with one permanent magnet each.

[Comparison between the first embodiment and the comparative example]
FIG. 5 is a comparison of inductance between the first embodiment and a comparative example. The vertical axis indicates the inductance of the linear motor, and the horizontal axis indicates the frequency of energizing the linear motor. The inductance of the comparative example is equivalent to that of the present embodiment on the low frequency side, but it drops significantly as the frequency rises, and drops to less than half on the high frequency side.

FIG. 6 is an explanatory diagram of a comparative example, and FIG. 7 is an explanatory diagram of the first embodiment. When the mover of the comparative example is constructed with an integrated metal frame, when it receives an alternating magnetic field generated by the armature, an eddy current is generated in the frame to counteract it, greatly reducing the inductance of the linear motor. Ta. On the other hand, since the mover frame of this embodiment is divided into the frame portion 121 and the bar portion 122, the electrical resistance of the contact portion (for example, the contact surface 122c) is large, and the eddy current is greatly reduced. Therefore, the inductance on the high frequency side is less likely to decrease. When the inductance on the high frequency side decreases, the impedance to the high frequency switching voltage of PWM (Pulse Width Modulation) decreases, current harmonics increase in the linear motor, and the efficiency of the linear motor decreases. According to this embodiment, it is possible to suppress a decrease in efficiency of the linear motor.

[Other effects of the first embodiment]
Permanent magnets 124a and 124b are fitted and inserted into groove 121b. Since the permanent magnets 124a and 124b have different polarities, when they approach each other, a strong magnetic attractive force is generated between them, and there is a risk of collision and damage. In this embodiment, as shown in FIG. 3, after inserting the permanent magnet 124a, after inserting the bar portion 122, the permanent magnet 124b is inserted. Therefore, by securing the distance between the permanent magnets 124a and 124b by the bar portion 122, it is possible to suppress the mutual collision and breakage due to the strong magnetic attraction force. By making the bar portion 122 of a relatively soft material such as resin (for example, polytetrafluoroethylene resin), it is possible to obtain an effect as a cushioning material against the magnetic attraction force when the magnet is inserted.

Moreover, since the bar portion 122 is provided between the permanent magnets 124a and 124b, the strength against the torsional force that the mover 12 receives can be improved.

<Second embodiment>
A linear motor according to the second embodiment will be described with reference to FIG. FIG. 8 is a sectional view perpendicular to the z-axis direction of the mover according to the second embodiment. Assuming that the distance between the surfaces of the frame arms 121a facing each other is A, and the length of the bar portion 122 in the x-axis direction is B, the relationship A>B gives a gap of AB in the x-axis direction inside the groove portion 121b. is made. Therefore, the contact area between the frame arm portion 121a and the bar portion 122 is reduced, the eddy current flowing in the frame is reduced, the eddy current loss in the frame and the current harmonics of the linear motor are reduced, and the efficiency of the linear motor is improved. can improve. Furthermore, by filling the gap between the frame arm portion 121a and the bar portion 122 with a non-conductive material (for example, adhesive), the insulation for suppressing the eddy current in the frame is strengthened and the mover Strength can be improved.

<Third Embodiment>
A linear motor according to a third embodiment will be described with reference to FIGS. 9 to 10. FIG. FIG. 9 is a view of the mover according to the third embodiment viewed from the y-axis direction. In this embodiment, the permanent magnets 124a and 124b are each divided into two, and the bar portion 122 is also provided between the divided permanent magnets. By providing a large number of bar portions, it is possible to improve the strength against the torsional force that the mover 12 receives.

FIG. 10 shows thrust waveforms when a direct current is applied to the windings 11b of the linear motor 10 according to the third embodiment, and the mover 12 is moved ±25 mm in the z-axis direction. Passing a positive current will generate a positive thrust, and passing a negative current will generate a negative thrust. As shown in FIG. 9, when the divided permanent magnets have the same length in the z-axis direction, the added bar portion 122 reduces the thrust in the vicinity of the position 0 mm. When the width of the bar portion 122 in the z-axis direction is increased, the degree of reduction in thrust increases, and the thrust amplitude at the central portion decreases. Therefore, it is desirable to reduce the width of the added bar portion 122 .

<Fourth Embodiment>
A linear motor according to a fourth embodiment will be described with reference to FIGS. 11 and 12. FIG. FIG. 11 is a view of the mover according to the fourth embodiment as seen from the y-axis direction. In this embodiment, each of the permanent magnets 124a and 124b is divided into two, and the bar portion 122 is also provided between the divided permanent magnets. Here, the z-axis direction lengths of the divided permanent magnets are a:b:b:a in order from the left.

FIG. 12 shows thrust waveforms when a direct current is applied to the windings 11b of the linear motor 10 according to the fourth embodiment, and the mover 12 is moved ±25 mm in the z-axis direction. Passing a positive current will generate a positive thrust, and passing a negative current will generate a negative thrust. As shown in FIG. 11, when the lengths of the divided permanent magnets in the z-axis direction are varied, the position at which the thrust decreases due to the added bar portion 122 is differentiated between the positive thrust and the negative thrust. be able to. Therefore, it is possible to suppress the decrease in thrust amplitude and improve the thrust amplitude in all regions.

Although the example of FIG. 11 shows the case where each of the permanent magnets 124a and 124b is divided into two, the present invention is not limited to this. That is, each of the permanent magnets 124a and 124b may be divided into three, and the bar portion 122 may be provided between the divided permanent magnets. Here, the z-axis direction lengths of the divided permanent magnets are a:b:c:c:b:a in order from the left.

<Fifth Embodiment>
[Configuration of the fifth embodiment]
FIG. 13 is a perspective view of the electromagnetic suspension 100 according to the fifth embodiment. In the following description, parts corresponding to those in the first embodiment described above are denoted by the same reference numerals, and description thereof may be 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. 14).

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 the fifth embodiment, a coil spring made of metal is applied as the elastic body 20 . Here, the elastic body 20 imparts elastic force to the stator 11 and is interposed between the stator 11 and the shaft fixture 23 . As shown in FIG. 13 , the mover 12 penetrates the stator 11 and also penetrates the elastic body 20 . Note that the elastic body 20 may bias the mover 12 .

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 .

In the fifth embodiment, two electromagnetic suspensions are used, but any number of suspensions may be used. Also, although this is an example in which only the electromagnetic suspension is supported, a combination of one hydraulic suspension and one electromagnetic suspension may be used. Furthermore, it may be combined with an actuator having a damping force other than a hydraulic damper.

[Effect of the fifth embodiment]
As described above, the electromagnetic suspension 100 of the fifth embodiment includes the linear motor 10 of the first embodiment and the elastic body 20 that biases the stator 11 or the mover 12 in the moving direction (z-axis direction). have. In particular, elastic body 20 includes a metallic coil spring. 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 can be prevented from passing through.

<Sixth Embodiment>
[Configuration of the sixth embodiment]
(overall structure)
FIG. 14 is a perspective view of the washing machine W according to the sixth embodiment. A washing machine W shown in FIG. 14 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 fifth embodiment.

The housing 32 includes left and right side plates 32a, 32a, a front cover 32b, a rear cover 32c (see FIG. 15), and a top cover 32d. The base 31 supports the housing 32 . A circular slot h1 (see FIG. 15) 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.

FIG. 15 is a longitudinal sectional view of washing machine W according to the sixth embodiment. The washing machine W includes a washing tub 35 for storing clothes, a lifter 36, a drive mechanism 38, and a blower unit 39, in addition to the configuration described above. 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. 15, 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. 15 , the outer tub 37 contains the washing tub 35 .

Further, as shown in FIG. 14, 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 . The rotating shaft of the motor provided in the drive mechanism 38 penetrates 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. 15 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. 16 is a configuration diagram of a vibration damping device 200 applied to the sixth embodiment. In FIG. 16, 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 addition, in the sixth embodiment, the damping object G is the outer tub 37 of the washing machine W (see FIGS. 14 and 15).

In FIG. 16, 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. 17 is a configuration diagram showing 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. 17, 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. 15 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 drive mechanism 38 that rotates the washing tub 35 (see FIG. 15). there is

The inverter 40 converts the DC voltage applied from the rectifier circuit 70 into two systems of single-phase AC voltages, and these two systems of single-phase AC voltages are applied 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. 17, the inverter 40 includes a first leg including switching elements SW1 and SW2, a second leg including switching elements SW3 and SW4, 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 using one inverter 40 in common for the left and right linear motors 10L and 10R instead of providing separate 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 currents supplied to 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. 16 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. 16, the thrust force adjustment unit 60 has a function of adjusting the thrust force 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. 15), 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 sixth embodiment]
As described above, the washing machine W of the sixth embodiment includes the electromagnetic suspensions 100L and 100R according to the fifth embodiment, the inverter 40 that supplies alternating current to the armature winding (winding 11b), and the armature winding a current detector 50 for detecting a current flowing through the linear motor 10;

Thus, the current detector 50 can detect the current flowing through the armature winding, and the thrust of the linear motor 10 can be adjusted so as to suppress the relative motion between the stator 11 and the mover 12 .

Furthermore, the washing machine W of the sixth embodiment includes a washing tub 35 for storing clothes, an outer tub 37 for enclosing the washing tub 35, and a drive mechanism 38 for rotating the washing tub, and includes electromagnetic suspensions 100L and 100R. suppresses the vibration of the outer tub 37 .

Thus, according to the sixth embodiment, vibration of the outer tub 37 can be suppressed with a relatively simple configuration. Further, according to the sixth 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 the mover 12, which are components of the linear motors 10L and 10R, are hardly damaged or worn, the durability of the electromagnetic suspensions 100L and 100R can be enhanced.

Further, according to the sixth 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 and 10R, eight switching elements are required. Therefore, according to the sixth embodiment, it is possible to reduce the cost of the washing machine W compared to a configuration in which separate inverters are provided corresponding to the left and right linear motors 10L and 10R.

<Seventh Embodiment>
Next, a washing machine according to a seventh embodiment will be described. The configuration and operation of the washing machine of the seventh embodiment are the same as those of the sixth embodiment (see FIGS. 14 to 17). However, in the seventh embodiment, the thrust force adjustment unit 60 (see FIG. 16) 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 the inverter 40 is adjusted according to the vibration frequency. is different in that it changes the output current of

First, in the sixth 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 sixth embodiment. On the other hand, in the seventh embodiment, the viscous damping coefficient C [Ns/m] is changed according to the vibration frequencies of the linear motors 10L and 10R. Details thereof will be described below.

A motion equation of the electromagnetic suspension 100 is represented by Equation (1). Note that FD [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 for the thrust of the linear motor 10 is represented by Equation (2). Note that FL [N] is the thrust force of the linear motor 10 and Ke [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 FD 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 .

Here, the gravitational energy (external force seen from the electromagnetic suspension) of the damping object Dt will be roughly calculated. According to the product catalog (Hitachi Global Life Solutions Co., Ltd. washing machine and clothes dryer general catalog 2019-summer), the mass of the drum washing machine with a maximum washing amount of 12 kg is 82 kg. Roughly speaking, the mass of mechanical parts such as the outer tub 37, the washing tub 35, and the driving mechanism 38 is about 70 kg. Also, assuming that about 40 L of water is poured into 12 kg of laundry, there is a total mass of 122 kg, and the gravitational energy is 1.2 kN. In other words, when two electromagnetic suspensions are applied, with a load of about 600 N/strain applied at the start of washing, the electromagnetic suspensions apply external force not only in the z-axis direction in FIG. receive. Furthermore, the electromagnetic suspension continues to generate a force that offsets these external forces from moment to moment.

Further, during dehydration, it is necessary to damp the centrifugal force caused by rotational imbalance that occurs when laundry containing residual moisture is biased in the washing tub 35 . During this period, the electromagnetic suspension receives external forces not only in the z-axis direction of FIG. 13 but also in the x-axis and y-axis directions.

FIG. 18 shows experimental results showing changes in the rotational speed of the washing tub 35 and the displacement (vibration) of the washing machine W in Comparative Example 1 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 washing machine W as a relative value when the rotation speed is zero. In the experiment shown in FIG. 18, the washing tub 35 was rotated with 1 kg of clothes placed at a predetermined position in the washing tub 35 (the same applies to FIG. 19, which will be described later).

As shown in FIG. 18, in the configuration of the comparative example, the amplitude of the washing machine W 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 washing machine W at a rotation speed of about 10%. The amplitude suddenly increases and reaches the maximum amplitude. In addition, the amplitude of the washing machine W increases at the rotation speed of 10 to 17 [%], and in the range of 20 [%] or more, the amplitude of the washing machine W decreases as the rotation speed of the washing tub 35 increases. there is

FIG. 19 shows experimental results showing changes in the rotational speed of the washing tub 35 and the displacement (vibration) of the washing machine W when the conventional electromagnetic suspension is applied to the seventh embodiment. In the experiment in FIG. 19, the duty ratio of the inverter 40 was adjusted so that the higher the rotational 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. 19, the maximum amplitude of the washing machine W when the rotation speed of the washing tub 35 is approximately 10 [%] is approximately 5 [PU], and the maximum amplitude of Comparative Example 1 shown in FIG. [PU]). Further, in the region where the rotation speed of the washing tub 35 is 50 [%] or more, the amplitude of the washing machine W is about 1 [PU]. Thus, according to the seventh embodiment, by variably controlling the viscous damping coefficient C, the vibration of the washing machine W is more effectively suppressed than in the comparative example using the oil damper with a constant viscous damping coefficient C. can.

FIG. 20 shows experimental results showing changes in the rotational speed of the washing tub 35 and the displacement (vibration) of the washing machine W when the electromagnetic suspension of the fifth embodiment is applied to the seventh embodiment. In the experiment in FIG. 20, the duty ratio of the inverter 40 was adjusted so that the higher the rotational 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.

The waveform of FIG. 20 clearly has a smaller amount of displacement of the outer tank than those of FIGS. Moreover, the effect is exhibited at all rotational speeds. As described above, according to the washing machine W to which the electromagnetic suspension 100 of the seventh embodiment is applied, it is possible to provide a washing machine with high damping properties.

[Modification]
The present invention is not limited to the embodiments described above, and various modifications are possible. The above-described embodiments are exemplified 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. 3, the mover 12 is configured by fitting two rectangular plate-like permanent magnets 124a and 124b into one frame portion 121. As shown in FIG. However, one magnet may be attached to one frame portion 121 . Also, a plurality of magnets may be attached to each of a plurality of frames. Further, the shapes of the frame portion 121 and the permanent magnets 124 are not limited to rectangular plate shapes, and various shapes can be adopted.

(2) In addition, in the sixth and seventh embodiments, the electromagnetic suspension 100 is applied to damping the washing machine W, but the electromagnetic suspension 100 can be It can also be applied to products, railway vehicles, automobiles, and the like.

(3) In each of the embodiments described above, 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.

(4) The material of the permanent magnet is assumed to be, for example, a rare earth sintered magnet. Other permanent magnets such as ferrite magnets may also be used. Alternatively, a reluctance motor or the like that does not use a permanent magnet may be used.

(5) The number of armatures is not limited to 1, but may be 3, 5, or any other odd number.

According to the present invention, the eddy current loss generated in the mover frame is reduced by reducing the eddy current in the mover frame (frame portion 121). Also, by reducing the magnetic attraction force when the magnet is inserted, damage to the magnet can be prevented.

10 linear motor 11 stator 11a core (armature core)
11a2 tooth portion 11b winding (armature winding)
12 mover 20, 20L, 20R elastic body 21 shaft 22 bearing 23 shaft fixture (fixing fixture)
31 base 32 housing 32a side plate 32b front cover 32c rear cover 32d top cover 33 door 34 operation/display panel 35 washing tub 36 lifter 37 outer tub 38 drive mechanism 38a inverter 38b motor 39 blower unit 40 inverter 50 current detector 60 thrust adjustment Section 70 Rectifier Circuit 72 Diode Bridge Circuit 74, 76 Smoothing Capacitor 100, 100L, 100R Electromagnetic Suspension 111 Arm 121 Frame 121a Frame Arm 121b Groove 122 Bar 122c Contact Surface 124, 124a, 124b Permanent Magnet 124f Surface (first side)
124r back surface (second surface)
200 damping device W washing machine

Claims (10)

a stator having an armature core and armature windings, a plurality of permanent magnets having first and second surfaces facing the stator, and facing the stator; In a linear motor comprising a mover that moves systematically,
The mover includes a frame portion and a plurality of bar portions,
the plurality of permanent magnets and the plurality of bar portions are inserted and fixed along grooves provided inside the frame portion so that the frame portion and the bar portion are in contact with each other at the contact surface; The linear motor, wherein the bar portion is provided between the permanent magnets. In the linear motor according to claim 1,
When the frame portion and the bar portion are made of a conductive material, the distance between the opposing surfaces of the frame arm portions having the grooves is A, and the length of the bar portion in the direction between the opposing surfaces is B. , A>B. In the linear motor according to claim 2,
A linear motor, wherein a gap formed between the frame arm portion and the bar portion is filled with a non-conductive material. In the linear motor according to claim 1,
A linear motor, wherein the bar portion between the plurality of permanent magnets is made of resin. In the linear motor according to claim 1,
A linear motor, wherein the plurality of permanent magnets are divided in the moving direction of the mover, and the bar portion is provided between the divided permanent magnets. In the linear motor according to claim 5,
The plurality of permanent magnets are divided into two in the movement direction of the mover, and the lengths of the two divided permanent magnets in the movement direction of the mover are symmetrical such as a:b and b:a. A linear motor characterized by: a pair of opposing shafts connecting the fixing brackets;
A linear motor according to any one of claims 1 to 6;
an elastic body mounted on the shaft and contracted between one of the fixing metal fittings and an arm of the stator, wherein the mover is fixed between the fixing metal fittings; suspension. In the electromagnetic suspension according to claim 7,
The electromagnetic suspension, wherein the elastic body is a coil spring made of metal. In the electromagnetic suspension according to claim 7,
an inverter that supplies alternating current to the armature winding;
a current detector that detects a current flowing through the armature winding;
and a thrust adjustment unit that controls the inverter based on the current detected by the current detector to adjust the thrust of the linear motor. an electromagnetic suspension according to claim 7;
a washing tub for storing clothes;
an outer tub containing the washing tub;
and a drive mechanism that rotates the washing tub,
The washing machine, wherein the electromagnetic suspension suppresses vibration of the outer tub.