JP6877263B2 - Linear actuator and vibration damping device for washing machines using it - Google Patents

Description

The present invention relates to a linear actuator that suppresses vibration generated in a vibration damping object, and a vibration damping device for a washing machine provided with the linear actuator.

Linear motors and linear actuators are being studied as electric machines that move linearly. Compared to a circular rotary motor that is geometrically symmetrical, a linear motor that is linear and has ends has a large number of parts and is complicated to assemble. Patent Document 1 describes a method for improving the productivity of a linear motor by linearly connecting the component parts (first magnetic teeth) of an armature molded into the same shape in advance. Further, there is also described an example in which a component is assembled without winding the first magnetic tooth and used as a magnetic tooth (second magnetic pole tooth) as a complementary pole.
Further, Patent Document 2 describes a structure in which a linear motor that can be vertically divided around a mover has an auxiliary pole.

Japanese Unexamined Patent Publication No. 2007-185033 Japanese Unexamined Patent Publication No. 2016-101019

The problem with linear motors is that they are larger in size and more expensive than rotary motors. Therefore, there are actuators on the market that perform linear motion by combining gears with a small, low-cost rotary motor. That is, it is cheaper to attach mechanical parts such as gears to an inexpensive rotary motor, and the physique may be smaller.

However, the technique described in Patent Document 1 targets a three-phase motor, and the magnetic teeth need to be arranged in multiples of 3 (FIG. 9), and the size is still large and the cost is high. Furthermore, even if the magnetic tooth is used as a complementary electrode, if the magnetic tooth is complemented as it is without winding, the cogging and torque ripple reduction effect is limited. Furthermore, since it is difficult to achieve magnetic balance with a three-phase motor, it has been shown that a third magnetic tooth is placed on both sides of the connecting component of the first magnetic tooth and the second magnetic tooth, and as a result, the number of components increases. It is a high-cost motor that is complicated to assemble (Fig. 11).

Further, even if the auxiliary poles (first auxiliary magnetic poles in FIG. 3) described in Patent Document 2 are arranged one above the other (FIG. 1), the magnetic flux vectors collide with each other in the auxiliary pole member, which affects the torque characteristics of the linear motor. I will not give it. That is, it depends on the auxiliary pole. Furthermore, the correlation between the magnet position, which is the detent source, and the mover position is insufficiently examined, and the detent pulsates positively and negatively across 0, and its reduction effect is limited (Fig. 7).

Further, in order to apply a linear motor / linear actuator for a vibration damping device, it is required to have extremely low cogging and low torque ripple within the movable range so that the motor does not become a vibration source. However, Patent Document 1 does not describe the use, and only vaguely describes a list of general theories that reduce cogging by supplementary poles. Patent Document 2 has a description for a compressor, which is different from that for damping. Therefore, the allowable detent torque ripple amount differs.

Therefore, the present invention provides a linear actuator that secures characteristics without increasing the size of the linear actuator and is excellent in economy. Furthermore, it is an object of the present invention to provide a damper and a vibration damping instruction mechanism using this linear actuator to household electric appliances such as a washing machine to improve the vibration damping property.

In order to solve the above problems, as an example in the present invention, in the linear actuator comprising a movable member which moves in opposition to the stator and the stator, the stator having a field coil, the field coil An auxiliary pole is provided between the magnetic teeth around which the stator is wound, the stator has a permanent magnet, and the stator has an annular portion in a longitudinal view and has an annular portion constituting a magnetic circuit. in the moving range of the movable element of the annular portion is the mover moves, a configuration poles of the permanent magnet facing the auxiliary electrode is constant.

According to the present invention, it is possible to provide a small-sized, low-cost, low-detent, low-torque ripple linear actuator. Further, the vibration damping device to which the linear actuator is applied can appropriately suppress the vibration of the vibration damping object with easy control and low cost. Further, by applying the vibration damping device to the vibration damping support mechanism of white goods such as a washing machine, it is possible to provide white goods and the like at low cost and excellent in vibration damping.

It is a vertical sectional perspective view of the linear actuator provided in the vibration damping device which concerns on 1st Embodiment of this invention. It is the end view of the arrow of the line II-II of FIG. It is the end view of the arrow of line III-III of FIG. It is a vertical sectional front view of the linear actuator included in the vibration damping device which concerns on 1st Embodiment of this invention. It is a vertical sectional front view of the linear actuator included in the vibration damping device which concerns on 1st Embodiment of this invention. It is an experimental result which shows the thrust characteristic of the linear actuator which concerns on embodiment of this invention. It is a figure which shows the relationship between the width of the auxiliary pole CP of the linear actuator which concerns on embodiment of this invention, and torque ripple. It is a contour figure which shows the in-machine magnetic flux density of the linear actuator which concerns on embodiment of this invention. It is an experimental result of the coil interlinkage magnetic flux of the linear actuator which concerns on embodiment of this invention. It is a perspective view of the vibration damping device which concerns on 1st Embodiment of this invention. It is a perspective view of the washing machine provided with the vibration damping device which concerns on 1st Embodiment of this invention. It is a vertical sectional view of the washing machine provided with the vibration damping device which concerns on 1st Embodiment of this invention. It is a block diagram of the vibration damping device which concerns on 1st Embodiment of this invention. It is a block diagram including the inverter included in the vibration damping device which concerns on 1st Embodiment of this invention. This is an experimental result showing changes in the rotation speed of the rinser and the displacement of the outer tank in a comparative example using an oil damper having a constant viscosity coefficient. In the embodiment of the present invention, it is an experimental result showing the change of the rotation speed of the washing tub and the displacement of the outer tub.

In each of the following embodiments, as an example, a configuration in which vibration of the washing machine W (see FIG. 10) is suppressed by a linear actuator 10 (see FIG. 1) will be described.

<< First Embodiment >>
FIG. 1 is a vertical cross-sectional view of a linear actuator 10 included in a vibration damping device.
As shown in FIG. 1, the xyz axis is defined. Further, in FIG. 1, half of the linear actuator 10 is shown in the x direction, but the configuration of the linear actuator 10 is symmetrical with respect to the yz plane.
The linear actuator 10 uses a magnetic attraction / repulsive force (that is, thrust) between the stator 11 which is an armature and the plate-shaped mover 12 extending in the z direction, thereby causing the stator 11 and the mover. It is an actuator that linearly changes the position relative to 12 in the z direction. As shown in FIG. 1, the linear actuator 10 is connected to the outer tub 37 (vibration damping object) of the washing machine W (see FIG. 11). Specifically, the mover 12 of the linear actuator 10 is connected to the outer tank 37.

As shown in FIG. 1, the linear actuator 10 includes a stator 11 and a mover 12. The stator 11 does not have a core 11a in which electromagnetic steel sheets are laminated in the z direction, a winding 11b wound around the magnetic pole teeth T of the core 11a, and a winding 11b wound around a convex portion of the core 11a. It has a complementary pole CP.

FIG. 2 is an end view taken along the line II-II of FIG. Note that FIG. 2 shows the entire linear actuator 10 instead of half of the linear actuator 10 in the x direction (see FIG. 1).
As shown in FIG. 2, the core 11a of the stator 11 includes an annular portion S1 and magnetic pole teeth T and T.
The annular portion S1 has an annular shape (rectangular frame shape) in a vertical cross-sectional view, and the annular portion S1 constitutes a magnetic circuit. The pair of magnetic pole teeth T, T extend inward in the y direction from the annular portion S1 and face each other. The distance between the magnetic pole teeth T and T is slightly longer than the thickness of the plate-shaped mover 12. Windings 11b are wound around the magnetic pole teeth T and T, respectively. By energizing the winding 11b, the stator 11 functions as an electromagnet.
The flow of magnetic flux generated from the electromagnet in the annular portion S1 and the permanent magnet (see FIG. 1) of the mover 12 is annular as shown by an arrow in the figure.

FIG. 3 is an end view taken along the line III-III of FIG. Note that FIG. 3 shows the entire linear actuator 10 instead of half of the linear actuator 10 in the x direction (see FIG. 1).
As shown in FIG. 3, the core 11a of the stator 11 includes an annular portion S2 and auxiliary pole teeth TCP and TCP.
The annular portion S2 has an annular shape (rectangular frame shape) in a vertical cross-sectional view, and the annular portion S2 constitutes a magnetic circuit. The pair of auxiliary pole teeth TCP and TCP extend inward in the y direction from the annular portion S2 and face each other. The distance between the auxiliary pole teeth TCP and TCP is slightly longer than the thickness of the plate-shaped mover 12. The winding 11b is not wound around the auxiliary pole teeth TCP and TCP.
The flow of magnetic flux generated from the mover 12 (not shown) in the annular portion S2 is annular as shown by a one-point arrow in the figure.
That is, the characteristics of the linear actuator 10 are determined by the sum of the magnetic flux vectors passing through the annular portion S1 of FIG. 2 and the annular portion S2 of FIG. That is, if you want to reduce the detent and torque ripple, you can optimize the sum of the magnetic flux vectors to meet the desired specifications.

In the example shown in FIG. 1, in the z direction (moving direction of the mover 12), two pairs of magnetic pole teeth T and a pair of auxiliary pole CPs are provided between the magnetic teeth T. In order to reduce the size of the linear actuator 10, it is preferable that the length of the auxiliary pole CP in the z direction is shorter than the length of the magnetic tooth T. Further, the winding 11b wound around each of the two pairs of magnetic pole teeth T forms one winding, and both ends thereof are connected to the output side of the inverter 40 (see FIG. 12) described later. ing.

The mover 12 shown in FIG. 1 penetrates the annular core 11a and extends in the z direction. Further, as shown in FIG. 1, the mover 12 includes a plurality of metal plates 12a extending in the z direction and permanent magnets 121b, 122b, 123b installed on the metal plates 12a at predetermined intervals in the z direction. It has. A plurality of permanent magnets may be attached to one metal plate, or a plurality of permanent magnets may be embedded in one metal plate.

The permanent magnets 121b, 122b, 123b shown in FIG. 1 are magnetized in the y direction. More specifically, the permanent magnets magnetized in the positive direction of the y direction (for example, permanent magnets 121b and 123b) and the permanent magnets magnetized in the negative direction of the y direction (for example, the permanent magnets 122b) are They are arranged alternately in the z direction. Then, a thrust in the z direction acts on the mover 12 by the attractive force and the repulsive force of the mover 12 and the stator 11 that functions as an electromagnet. The "thrust" is a force that changes the relative positions of the mover 12 and the stator 11.

Further, it is desirable to use samarium-iron-nitrogen permanent magnets as the permanent magnets 121b, 122b, 123b. The specific ratios (% by weight) of the raw materials of the permanent magnets 121b, 122b, 123b are, for example, iron: about 73%, samarium: about 24%, and nitrogen: about 3%. Among the above-mentioned raw materials, the rare earth element is samarium.

On the other hand, in the conventional neodymium magnets, iron: about 65%, neodymium: about 28%, dysprosium: about 5%, and boron: about 2% were often used. Among the above-mentioned raw materials, rare earth elements are neodymium and dysprosium. Therefore, the samarium-iron-nitrogen permanent magnets 121b, 122b, and 123b have the advantage that they are less affected by market trends and lead to improved productivity because the proportion of rare earth elements is smaller than that of conventional neodymium magnets. ..

Further, unlike the conventional neodymium magnets and ferrite magnets, the samarium-iron-nitrogen permanent magnets 121b, 122b, and 123b can be kneaded into a resin and molded. Therefore, the processing accuracy of the permanent magnets 121b, 122b, 123b can be improved and the dimensional variation thereof can be reduced as compared with the conventional case. Further, since the waste portion of the raw material remains in the mold molding, it can be reused, so that the loss of the raw material is eliminated and the manufacturing cost can be reduced.

The length of the permanent magnet 122b shown in FIG. 1 in the z direction is set to be larger than the sum of the length of the movable range X of the mover 12 and the length of the auxiliary pole CP in the z direction. As a result, the polarity of the permanent magnet 122b facing the auxiliary pole CP becomes constant. That is, unlike a general linear actuator, the polarity of the permanent magnet facing the auxiliary pole CP does not change from N pole, S pole ... N pole.

4-1 and 4-2 are vertical sectional front views of the linear actuator 10 included in the vibration damping device.

The description will be described in detail with reference to FIGS. 4-1 and 4-2. In the linear actuator 10 shown in FIG. 4-1 (a), the length in the z direction is such that the length TL of the magnetic tooth T is longer than the movable range X of the mover 12, and the length ML of the permanent magnet 122b is magnetic. It is preferably larger than the tooth pitch TP. FIG. 4-1 (b) is an example of the direction of the magnetic flux when the coil is energized (the mover 12 is not shown for explanation). The magnetic pole arrangement when the winding 11b is energized so that the core 11a becomes a magnetic pole is shown. Each magnetic tooth T has an N pole and an S pole, respectively, but the auxiliary pole CP is neutral because the energization directions of adjacent coils are the same. Further, FIG. 4-1 (c) shows a case where the winding 11b is energized in the opposite direction of FIG. 4-1 (b), and each magnetic tooth T can be inverted to the S pole and the N pole. FIG. 4-2 (d) is an example of the direction of the magnetic flux of the permanent magnet. The linear actuator 10 of this embodiment controls the attractive force of the magnetic force and generates thrust by switching the direction of the current of the winding 11b. FIG. 4-2 (e) shows the left end of the movable range of the linear actuator 10, and FIG. 4-2 (f) shows the right end. In this embodiment, both the two pairs of magnetic teeth T and the auxiliary pole CP face the permanent magnet 122b even at the left end and the right end of the moving range of the mover 12. As a result, even if the coil is not energized (Fig. 4-2 (d)), even if the mover is at the left end and the magnetic flux of the permanent magnetic flux and the magnetic flux of the electromagnet have the same vector (Fig. 4-2 (e)). Even if the mover is at the right end and the magnetic flux of the permanent magnetic flux and the magnetic flux of the electromagnet are inverse vectors (Fig. 4-2 (f)), they are in the same direction as the auxiliary pole CP (solid line downward in the figure). It is a magnetic path of magnetic flux (arrow).

FIG. 5 is an experimental result showing the thrust of the linear actuator according to this embodiment. The horizontal axis shows the movement range of the mover 12, and the vertical axis shows the thrust. Conventionally, the thrust changes as the mover moves. The maximum thrust is 180N when the mover 12 is at the center (displacement 0 mm), while the minimum thrust is 40N when the mover is at the left end. That is, 140 N of torque ripple is generated with respect to the movement of the mover 12. That is, it is difficult to control because the characteristics of the linear actuator differ greatly depending on the position of the mover, and the linear actuator itself is the vibration source. In this embodiment, the fluctuation of the thrust is small with respect to the movement of the mover 12, and the maximum value is 180N and the minimum value is 160N and 20N. Therefore, it is a quiet linear actuator that is easy to control. At this time, the length of the stator 11 in the z direction is 80 mm, the length of the magnetic tooth T is 20 mm, and the length of the auxiliary pole CP is 10 mm.

FIG. 6 is a diagram showing the relationship between the width of the auxiliary pole CP of the linear actuator and the torque ripple according to this embodiment.
The horizontal axis shows the ratio of complementary poles, and the vertical axis shows the ratio of torque ripple. The ratio of the complementary pole was (length of complementary pole CP) / (length of magnetic tooth T) × 100 (%). The ratio of torque ripple was (torque ripple) / (maximum thrust) × 100 (%). In the above case, the ratio of complementary poles is 50% and the ratio of torque ripple is 11%.
When the compensating pole CP was changed constantly for the magnetic tooth T, it was found that the torque ripple could be reduced even if the commutating pole ratio was 10%. That is, even if the width of the auxiliary pole CP is small, it is effective, and the thrust characteristics of the linear actuator 10 can be made constant without increasing the overall length of the stator 11.

Further, the auxiliary pole is a press-molded product of an electromagnetic steel plate as shown in FIG. 3. For example, when the width of the auxiliary pole CP is 2 mm (corresponding to 10% of the above), a commercially available 0.50 mm thick electromagnetic steel plate is used. If you use it, you only need to stack 4 more sheets. In other words, the material cost and processing cost are insignificant, and there is a linear actuator without increasing the cost. For example, the thrust characteristics of 10 could be improved.

FIG. 7 is a contour diagram showing the in-machine magnetic flux density of the linear actuator according to this embodiment. In order to confirm the effect of the auxiliary pole CP, the analysis result of the magnetic flux density in the machine is shown. Since the magnetic flux cannot be visualized, simulation analysis was used. Commercially available magnetic field analysis software (JMAG-Designer manufactured by JSOL Corporation) was used for the simulation.

FIG. 7 (a) is a model without the auxiliary pole CP of the conventional example, and FIG. 7 (b) is a model with the auxiliary pole of the present embodiment. The analysis model is unified in order to eliminate the difference in the analysis conditions such as the number of meshes. That is, in the auxiliary pole portion of FIG. 7 (a), the material is changed to air (no auxiliary pole) for analysis.
Further, these contour diagrams show a case where the displacement -10 mm in FIG. 5, that is, the mover 12 in FIG. 4 is at the left end.
In FIG. 7A, the magnetic flux densities of the annular portion S of the stator 11 are different on the left and right (the portion circled in the figure). That is, the annular portion S on the side where the magnetic flux of the field magnet and the magnetic flux match the magnet (right side in the figure) is magnetically saturated, and the annular portion on the side where the magnetic flux of the field magnet and the magnetic flux of the magnet cancel each other (left side in the figure). S is not magnetically saturated, indicating that the magnetic flux density distribution in the machine is non-uniform.
On the other hand, in FIG. 7B, the magnetic flux densities of the annular portion S of the stator 11 are substantially the same. It can also be confirmed that the magnetic flux passes through the annular portion S of the auxiliary pole TS. In other words, it was confirmed that the magnetic flux density distribution in the machine was made uniform by the action of the auxiliary pole CP.

FIG. 8 shows the experimental results of the coil interlinkage magnetic flux of the linear actuator according to this embodiment. The horizontal axis shows the movement range of the mover 12, and the vertical axis shows the interlinkage magnetic flux. The difference between the conventional example and this embodiment is small when no power is applied (at DC0A). However, when energized (when DC1A is energized), it can be seen that in the conventional example, as the displacement advances in the positive direction, the displacement deviates from the straight line and becomes saturated. On the other hand, in the present invention, the interlinkage magnetic flux of the coil changes substantially linearly according to the movement of the mover. That is, it means that various characteristics such as the induced voltage of the linear actuator of the present invention change at a substantially constant rate with the movement of the mover. This indicates that the correlation can be calculated if either the position of the mover or the behavior of the linear actuator is known. In other words, it is not necessary to control using the position sensor of the mover of the invented linear actuator, and the position of the mover can be estimated from physical quantities such as the induced voltage generated by the movement of the mover, resulting in a so-called sensorless linear actuator. ing.

FIG. 9 is a perspective view of the vibration damping device 100 including the linear actuator 10.
The vibration damping device 100 is an electromagnetic suspension including the linear actuator 10 and the spring 20 described above, and is a vibration of the outer tub 37 which is a “vibration damping object” (that is, vibration of the washing machine W: see FIG. 11). It has a function of suppressing.

As shown in FIG. 9, one end of the mover 12 of the linear actuator 10 is connected to the outer tub 37 of the washing machine W (see FIG. 11), and the other end is connected to the fixing jig J. Further, although the stator 11 of the linear actuator 10 is not shown, its movement is restricted by another fixing jig (not shown). Therefore, when the outer tub 37 of the washing machine W vibrates in the z direction, the mover 12 reciprocates in the z direction, and the relative positional relationship between the mover 12 and the stator 11 changes. There is.

The spring 20 is a spring that applies an elastic force to the stator 11, and is interposed between the stator 11 and the fixing jig J. As shown in FIG. 9, the mover 12 penetrates the stator 11 and also the spring 20.

FIG. 10 is a perspective view of the washing machine W provided with the vibration damping device 100.
Since the vibration damping device 100 is installed inside the washing machine W (see FIG. 11), the vibration damping device 100 is not shown in FIG.
The 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 the vibration damping device 100 (see FIG. 11), a base 31, a housing 32, a door 33, an operation / display panel 34, and a drain hose H.

The base 31 supports the housing 32.
The housing 32 includes left and right side plates 32a and 32a, a front cover 32b, a back cover 32c (see FIG. 11), and a top cover 32d. A circular input port h1 (see FIG. 11) for taking in and out clothes is formed near the center of the front cover 32b.
The door 33 is an openable / closable lid provided at the inlet h1 described above.

The operation / display panel 34 is a panel provided with an electric switch, an operation switch, a display, and the like, and is installed on the upper surface cover 32d.
The drain hose H is a hose for draining the washing water of the outer tub 37 (see FIG. 11), and is connected to the outer tub 37.

FIG. 11 is a vertical cross-sectional view of the washing machine W provided with the vibration damping device 100.
In addition to the above-described configuration, the washing machine W includes a washing tub 35, a lifter 36, an outer tub 37, a drive mechanism 38, and a blower unit 39.
The washing tub 35 accommodates clothes and has a bottomed cylindrical shape. The washing tub 35 is contained in the outer tub 37 and is rotatably supported on the same axis as the outer tub 37. The peripheral wall and bottom wall of the washing tub 35 are provided with a large number of through holes (not shown) for water passage and ventilation. Further, the opening h2 of the washing tub 35 faces the closed door 33 together with the opening h3 of the outer tub 37.

In the example shown in FIG. 11, the rotation center axis 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 rotation center axis of the washing tub 35 may be in the horizontal direction or in the vertical direction.
The lifter 36 lifts and drops 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 bottomed cylindrical shape. As shown in FIG. 5, the outer tub 37 includes a washing tub 35. Linear actuators 10 (stator 11 and mover 12) and springs 20 are installed on the left and right sides of the outer tank 37, respectively. Note that FIG. 5 shows one of the left and right linear actuators 10.

Further, a drainage hole (not shown) is provided at the lowermost part of the bottom wall of the outer tank 37, and a drainage hose H is connected to this drainage hole. Then, the washing water is stored in the outer tub 37 in a state where the drain valve (not shown) provided in the drain hose H is closed, and the washing water is discharged by opening the drain valve. It has become 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 38b (see FIG. 7) included 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 blows warm 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 to the washing tub 35 by the fan. As a result, the clothes containing water are gradually dried in the washing tub 35.

FIG. 12 is a configuration diagram of the vibration damping device 100. In FIG. 12, one of the two left and right linear actuators 10 is illustrated, and the other is omitted. The vibration damping object G shown in FIG. 6 is the outer tub 37 (see FIG. 11) of the washing machine W (see FIG. 11).
The vibration damping device 100 includes an inverter 40, a current detector 50, and a thrust adjusting unit 60, in addition to the above-described configuration (linear actuator 10 and spring 20: see FIG. 9).

The inverter 40 converts the DC voltage applied from the rectifying circuit F into a ^{single-phase AC voltage based on the voltage command V *} from the thrust adjusting unit 60, and converts this single-phase AC voltage into the winding 11b (winding 11b) of the linear actuator 10. It is a power converter applied to (see FIG. 2). That is, the inverter 40 has a function of driving the linear actuator 10 based on the ^{voltage command V * described above.}
The "DC power supply" that applies a DC voltage to the inverter 40 includes an AC power supply E and a rectifier circuit F.

FIG. 13 is a configuration diagram including an inverter 40 included in the vibration damping device 100.
In FIG. 13, the linear actuator on the left side is referred to as “linear actuator 10L”, and the linear actuator on the right side is referred to as “linear actuator 10R”.
The rectifier circuit F shown in FIG. 13 is a well-known voltage doubler rectifier circuit that converts an AC voltage applied from an AC power supply E into a DC voltage. As shown in FIG. 7, the rectifier circuit F includes a diode bridge circuit F1 in which diodes D1 to D4 are bridge-connected, and two smoothing capacitors C connected in series.

Then, the voltage applied from the diode bridge circuit F1 (DC voltage including pulsating current) is smoothed by the smoothing capacitor C, and a DC voltage corresponding to approximately twice the voltage of the AC power supply E is generated. ing.
The rectifier circuit F is connected to the inverter 40 via the wiring k1 on the positive side and the wiring k2 on the negative side, and is also connected to the inverter 38a of the drive mechanism 38 that rotates the washing tub 35 (see FIG. 10). There is. The drive mechanism 38 includes an inverter 38a and a motor 38b.

The inverter 40 converts the DC voltage applied from the above-mentioned "DC power supply" into a single-phase AC voltage, and applies this single-phase AC voltage to the windings 11b (see FIG. 2) of the linear actuators 10L and 10R. It is a full bridge inverter.
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. As these switching elements SW1 to SW6, for example, an IGBT (Insulated Gate Bipolar Transistor) can be used. A freewheeling diode D is connected in antiparallel to each of the switching elements SW1 to SW6.

Further, the connection points of the switching elements SW1 and SW2 are connected to the winding 11b (see FIG. 2) of the linear actuator 10L via the wiring k3. That is, the leg corresponding to one phase of the three-phase inverter 40 is connected to the linear actuator 10L on the left side (one side).

Further, the connection points of the switching elements SW5 and SW6 are connected to the winding 11b (see FIG. 2) of the linear actuator 10R via the wiring k5. That is, another leg corresponding to one phase of the three-phase inverter 40 is connected to the linear actuator 10L on the right side (the other side).

Further, the connection points of the switching elements SW3 and SW4 are connected to the winding 11b (see FIG. 2) of the linear actuator 10L via the wiring k4, and also to the winding 11b of the linear actuator 10R via the wiring k4. It is connected. That is, the remaining legs of the three-phase inverter 40 are connected to the linear actuator 10L on the left side (one side) and the linear actuator 10R on the right side (the other side).

In this way, the cost of the inverter 40 can be reduced by sharing the left and right as one inverter 40 instead of separately providing the inverters corresponding to the left and right linear actuators 10L and 10R. Then, by controlling the on / off of the switching elements SW1 to SW6 based on PWM control (Pulse Width Modulation), a single-phase AC voltage is applied to the windings 11b (see FIG. 2) of the linear actuators 10L and 10R. It has become so.

The current detector 50 detects the current applied to the linear actuators 10L and 10R, and is provided in the wiring k4. That is, the current detector 50 detects the current flowing through the windings 11b (see FIG. 2) of the linear actuators 10L and 10R.

Although not shown, the thrust adjusting unit 60 shown in FIG. 6 includes electronic circuits such as a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and various interfaces. Then, the program stored in the ROM is read out and expanded in the RAM, and the CPU executes various processes.

The thrust adjusting unit 60 has a function of adjusting the thrust of the linear actuator 10 by driving the inverter 40 based on the current i detected by the current detector 50. ^{That is, the thrust adjusting unit 60 generates a predetermined voltage command V *} based on the current i described above, and switches the switching elements SW1 to SW6 on and off based on the voltage command V ^*. Details will be described later, but when the relative positions of the mover 12 and the stator 11 change due to the vibration of the outer tank 37 (see FIG. 5), the thrust adjusting unit 60 cancels this change with the linear actuator 10. It is designed to adjust the thrust of.

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 washing tub 35 is rotated at a low speed by the drive mechanism 38 shown in FIG. 5, and the tumbling operation of lifting and dropping the clothes collected on the bottom of the washing tub 35 by the lifter 36 is repeated. Further, during dehydration, the washing tub 35 rotates at high speed, and centrifugal dehydration is performed to push out the moisture of the clothes by the centrifugal force due to the rotation.

In a conventional washing machine, the amplitude of vibration of the washing tub 35 often increases due to the reaction force of falling clothes during washing, rinsing, and drying. Further, in the conventional washing machine, vibration and noise are often generated in the washing machine W due to the bias of the position of clothes during dehydration. In this way, the way the washing machine W vibrates changes from moment to moment depending on various conditions such as washing, rinsing, drying, and dehydration, in addition to the amount and position of clothes in the washing tub 35 and the water content. The vibration propagates to the outer tank 37.

<Effect>
According to the first embodiment, the thrust adjusting unit 60 generates a thrust so as to cancel the vibration of the outer tank 37 based on the current i flowing through the linear actuator 10. As a result, the vibration damping device 100 can appropriately suppress the vibration of the outer tank 37 by a relatively simple method.

Further, according to the first embodiment, it is not necessary to provide a position sensor for detecting the position of the mover 12, so that the cost of the washing machine W can be reduced. Further, since the linear actuator 10 hardly causes damage or wear of its components (stator 11 and mover 12), the durability of the vibration damping device 100 can be improved.

Further, the single-phase AC voltage applied to the left and right linear actuators 10L and 10R (see FIG. 7) is generated by one inverter 40. Therefore, the cost of the washing machine W can be reduced as compared with the configuration in which the inverters are separately provided corresponding to the left and right linear actuators 10L and 10R.

Further, by using the Samalium-iron-nitrogen permanent magnets 121b, 122b, 123b (see FIG. 1), as described above, the permanent magnets 121b, 122b, 123b can be compared with the conventional technique using the neodymium magnet. Cost reduction can be achieved. Therefore, the manufacturing cost of the washing machine W can be reduced.

<< Modified example of the first embodiment >>
In the first embodiment, the current proportional gain Kp in the thrust adjusting unit 60 has been described as being constant, but by changing the magnitude of the current proportional gain Kp, the viscosity coefficient C [Ns / m] of the linear actuator 10 is changed. May be changed. A method of changing the viscosity coefficient C will be described.

The equation of motion of the vibration damping device 100, which is an electromagnetic suspension, is expressed by the following equation (1). Incidentally, _F D [N] shown in equation (1) is a force generated by the vibration damping device 100 (i.e., the thrust of the linear actuator 10). Further, x [m] is the position of the mover 12.

The equation of motion of the thrust of the linear actuator 10 is expressed by the equation (2). _FL [N] is the thrust of the linear actuator 10, and Ke [N / A] is the motor constant of the linear actuator 10. Further, I [A] is a current flowing through the winding 11b (see FIG. 2), and V [V] is a voltage applied to the winding 11b. Further, R [Ω] is the resistance of the winding 11b, and φ [T] is the magnetic flux generated in the winding 11b.

Here, the force _{F D} of the formula (1), since the thrust _{F L} of formula (2), are equivalent, the following equation (3) is derived. C [Nm / rad] is the viscosity coefficient of the linear actuator 10.

FIG. 14A is an experimental result showing changes in the rotation speed of the washing tub 35 and the displacement (vibration) of the outer tub 37 in a comparative example using an oil damper having a constant viscosity coefficient C.
In the experiment of FIG. 14A, the washing tub 35 was rotated with 1 kg of clothes placed in a biased predetermined position in the washing tub 35 (the same applies to FIG. 14B).

As shown in FIG. 14A, 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 50 [min -1 ], and at a rotation speed of about 100 [min -1} ]. The amplitude of the outer tank 37 suddenly increases to the maximum amplitude. Further, the amplitude of the outer tub 37 increases at a rotation speed of 105 to 170 [min ^{-1 ], and in the region of 200 [min -1} ] or more, the amplitude of the outer tub 37 increases as the rotation speed of the washing tub 35 increases. Is getting smaller.

FIG. 14B is an experimental result showing changes in the rotation speed of the washing tub 35 and the displacement (vibration) of the outer tub 37 in the second embodiment.
In the experiment shown in FIG. 14B, 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 viscosity coefficient C of the linear actuator 10.
As shown in FIG. 14B, the maximum amplitude of the outer tub 37 when the rotation speed of the washing tub 35 is about 100 [min ^-1 ] is about 5 mm, which is the maximum amplitude (about 10 mm) of the comparative example shown in FIG. 12A. It is about half. Further, in the region where the rotation speed of the washing tub 35 is 500 [min ^-1 ] or more, the amplitude of the outer tub 37 is about 1 mm. As described above, according to the second embodiment, by variably controlling the viscosity coefficient C, the vibration of the outer tank 37 can be suppressed more effectively than in the first embodiment.

Further, in each embodiment, the configuration in which the spring 20 is provided between the stator 11 (see FIG. 9) and the fixing jig J has been described, but the present invention is not limited to this. For example, instead of the spring 20, a mechanism using rubber or hydraulic pressure may be applied.

Further, in each embodiment, the configuration in which the mover 12 is connected to the outer tank 37, which is the vibration damping target, has been described, but the present invention is not limited to this. That is, one of the stator 11 and the mover 12 may be connected to the vibration damping object, and the relative positions of the stator 11 and the mover 12 may be changed by a magnetic attraction / repulsion force.

Further, in each embodiment, the configuration in which the washing machine W is vibration-damped by the vibration-damping device 100 or the like has been described, but the present invention is not limited to this. For example, in addition to home appliances such as air conditioners and refrigerators, each embodiment can be applied to railway vehicles, automobiles, and the like.
Further, in each embodiment, the configuration for driving the linear actuator 10 with single-phase AC power has been described, but for example, the linear actuator 10 may be driven with three-phase AC power.

Further, the embodiments are described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those including all the configurations described. Further, it is possible to add / delete / replace a part of the configuration of the embodiment with another configuration.
In addition, the above-mentioned mechanism and configuration show what is considered necessary for explanation, and do not necessarily show all the mechanisms and configurations in the product.

100 Vibration damping device 10 Linear actuator 10L Linear actuator (one linear actuator)
10R linear actuator (the other linear actuator)
11 Stator 12 Movable elements 121b, 122b, 123b Permanent magnet 20 Spring 35 Washing tub 37 Outer tub (vibration damping object)
38 Drive mechanism 40 Inverter 50 Current detector 60, Thrust adjustment unit G Vibration control target W Washing machine CP Auxiliary pole

Claims (7)

In a linear actuator including a stator and a mover that moves in opposition to the stator.
The stator has a field coil , an auxiliary pole is provided between the magnetic teeth around which the field coil is wound, and the mover has a permanent magnet .
The stator exhibits an annular shape in a vertical cross-sectional view, has an annular portion constituting a magnetic circuit, and is permanently opposed to the auxiliary pole in the movement range of the actuator in which the mover moves in the annular portion. A linear actuator characterized in that the magnetic poles of a magnet are constant. In the linear actuator according to claim 1,
_{The length TL} of the magnetic tooth portion into which the field coil is wound is longer than the movable range X of the linear actuator.
Linear actuator length M _L of the permanent magnet is equal to or larger than the pitch T _P of the magnetic teeth. The linear actuator according to claim 1 or 2 is provided.
The linear actuator is connected to the vibration damping object and
The inverter that drives the linear actuator and
A current detector that detects the current applied to the linear actuator, and
Based on the current detected by the current detector
By driving the inverter
A vibration damping device including a thrust adjusting unit that adjusts the thrust of the linear actuator. Equipped with the pair of linear actuators driven by single-phase AC power,
The inverter is a three-phase full bridge inverter.
The leg corresponding to one phase of the three-phase full bridge inverter is connected to one of the linear actuators.
The vibration damping device according to claim 3, wherein a leg corresponding to one phase of the three-phase full-bridge inverter is connected to one and the other linear actuator. The permanent magnet of the linear actuator
The vibration damping device according to claim 1, wherein the permanent magnet is a samarium-iron-nitrogen system. The vibration damping device according to claim 1, further comprising the linear actuator and an elastic body. A washing tub for storing clothes and
An outer tub containing the washing tub and
The drive mechanism that rotates the washing tub and
A linear actuator connected to the outer tank, which is a vibration damping object, is provided.
The linear actuator comprises a stator and a mover that moves against the stator.
The stator has a field coil , an auxiliary pole is provided between the magnetic teeth around which the field coil is wound, and the mover has a permanent magnet .
The stator exhibits an annular shape in a vertical cross-sectional view, has an annular portion constituting a magnetic circuit, and is permanently opposed to the auxiliary pole in the movement range of the mover in which the mover moves in the annular portion. A washing machine characterized in that the magnetic poles of magnets are constant.

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