JP2013081543A - Vertical type washer - Google Patents

Abstract

An object of the present invention is to obtain a position of a rolling element for balance provided so as to be movable in a circumferential direction with respect to a rotating shaft of a drum in a state where the drum is rotating at a low speed before exceeding a resonance rotational speed. Provided is a vertical washing machine capable of greatly reducing vibrations generated when exceeding a resonance rotational speed.
A drum 1 that is rotatably supported around a vertical axis and receives an eccentric load due to bias of laundry W accommodated therein, an electric motor 3 that rotationally drives the drum 1, and the drum 1 or a plurality of balancing rolling elements 21 which are attached to 1 in a circumferentially movable manner and move in a direction to cancel out the unbalance due to the eccentric load, and a rotation which drives the electric motor to control the rotation speed of the drum A vertical washing machine having a control unit 4, wherein the rotation control unit 4 maintains a first rotation speed that is slightly lower than a resonance rotation speed of the drum 1 for a predetermined time, and then the resonance. It was configured to increase the rotational speed higher than the rotational speed.
[Selection] Figure 2

Description

  The present invention relates to a vertical washing machine including a ball balancer for reducing imbalance in a drum and reducing vibration of the drum.

  For example, in the washing machine dewatering process, the individual laundry is often placed in a non-uniform or unbalanced state along the inner circumference of the drum. As a result, a biased force is applied to the rotating shaft during dehydration, and vibration is generated. The amplitude of vibration increases in proportion to the square of the rotational speed of the rotating drum, and the vibration causes problems such as the washing machine itself moving or being unable to operate at a certain rotational speed or higher. Occur.

  Therefore, the vertical washing machine disclosed in Patent Document 1 is configured to reduce the unbalance of the laundry in the drum during rotation by providing a ball balancer at the upper circumferential end of the drum. More specifically, in the ball balancer, a plurality of balls having a degree of freedom in the rotational direction (circumferential direction) are arranged in a tubular race portion attached to the inner periphery of the drum, and at a speed higher than the resonance rotational speed. The balance device utilizes a dynamic phenomenon in which a ball automatically moves to an opposite phase position with respect to an unbalanced body (in this case, a laundry (cloth)) that generates an eccentric load by rotating.

  By the way, when the rotational speed of the drum is shifted from a low rotational speed to a high rotational speed in a dehydration process or the like, if the laundry is unbalanced in the drum, the resonant rotational speed When the frequency exceeds 1, vibration with a very large amplitude is generated as compared with when no imbalance occurs, and noise and the like become a problem. If the laundry in the drum and each ball constituting the ball balancer are in the same phase position on the same side, the unbalance amount of the drum is the largest, so the amplitude generated when the resonance rotational speed is exceeded is also the maximum. End up.

  However, in the ball balancer provided in the conventional vertical washing machine, the position of the laundry in the drum and the ball balancer ball are previously set before the drum exceeds the resonance rotation speed in order to reduce the vibration at the resonance rotation speed. The position of was not changed to the reciprocal position. This is because the ball balancer used in the vertical washing machine and configured to be movable in a horizontal plane is considered to have the characteristics described below.

  First, in the case of a ball balancer attached to an oblique drum or a horizontal drum, when the drum is stopped as shown in FIG. 6, the balls are gathered downward by gravity. Therefore, since the initial position of each ball is clear, it is possible to accurately grasp the position of each ball with respect to the unbalance of the laundry or the like even in a low speed range that does not exceed the resonance rotational speed.

  On the other hand, when a ball balancer is used in a vertical washing machine, each ball is in a horizontal plane as shown in FIG. 6, so when the drum is stopped, the position of each ball is uniquely determined. Indefinite. In other words, as long as the initial position of each ball is not known, even if there is a method of changing the position of each ball, how much each ball should be moved before the drum exceeds the resonance rotational speed, I don't know if it will be in an unbalanced or anti-phase position.

  Furthermore, in the case of a ball balancer provided on an oblique drum or a horizontal drum, if the drum is rotated at a constant speed lower than the resonance rotation speed, the circumference of each ball and the laundry is shown in the graph of FIG. Gravity affects the rotational speed in the direction, and each rotational speed is slightly different. In other words, relative movement occurs between the laundry and each ball simply by moving the drum at a constant speed lower than the resonance rotational speed. Can be moved to the opposite phase position.

  On the other hand, in a ball balancer used in a vertical washing machine, the influence of gravity does not occur on the circumferential movement. Since the relative speed in the circumferential direction does not occur between the balls and the laundry, the balls are substantially synchronized with each other, so that each ball cannot be moved to the opposite phase position with respect to the laundry. That is, in the conventional vertical washing machine, vibration when the drum rotation speed exceeds the resonance rotation speed cannot be sufficiently reduced.

  By the way, as one method for solving the problem that the initial position of the ball balancer used in the vertical washing machine is indefinite, it is sufficiently lower than the resonance rotational speed of the drum as shown in the graph of FIG. There is a method of collecting the laundry and each ball in the same phase position while maintaining the rotation speed. With this method that has been used in the past, the initial position of each ball can be specified before the drum exceeds the resonance rotational speed, but each ball is fixed at a position farthest from the reciprocal position. Therefore, even if there is a means for moving each ball, the amount of movement becomes large, and for example, it takes a long time for each ball to reach the opposite phase position. Furthermore, in the case of a ball balancer used in a vertical washing machine as shown in Patent Document 2, each ball and laundry can be used at any speed as long as the speed is lower than the resonance rotational speed. Because the position was thought to be in phase, it was impossible to accurately grasp the position of each ball close to the antiphase position before it greatly exceeded the resonant rotation speed. It was thought to be.

  As described above, in the ball balancer used in the conventional vertical washing machine, it is considered that the position of each ball cannot be grasped without using a sensor or the like while the drum rotates at a low speed. Furthermore, no effective moving method has been found in which each ball is moved before the resonance rotational speed is exceeded and the laundry and each ball are in opposite positions.

JP 2005-21505 A JP 2010-125083 A

  Therefore, the present invention has been made in view of the above-described problems, and is provided so as to be movable in the circumferential direction with respect to the rotation axis of the drum in a state where the drum is rotating at a low speed before exceeding the resonance rotational speed. It is a first object to grasp the position of the balance rolling element substantially accurately. Furthermore, the present invention is based on the fact that the laundry and the ball are moved to the opposite phase positions based on the grasped position of the balancing rolling element, and the vibration generated when the drum exceeds the resonance rotational speed is greatly reduced. Let it be the second issue. And it aims at providing the vertical washing machine which can solve these subjects.

  That is, a drum that is supported rotatably around a vertical axis and is subjected to an eccentric load due to bias of the laundry accommodated therein, an electric motor that rotationally drives the drum, and a circumferential rolling on the drum A vertical type equipped with one or a plurality of balancing rolling elements that are attached so as to move in a direction to cancel the unbalance due to the eccentric load, and a rotation control unit that drives the motor to control the rotation speed of the drum. In the washing machine, the rotation control unit maintains a first rotation speed that is slightly lower than the resonance rotation speed of the drum for a certain period of time, and then increases the rotation speed to a rotation speed higher than the resonance rotation speed. It is comprised by these.

  As a result of intensive studies by the inventors of the present invention, the configuration of the present invention has been kept constant at a low-speed rotation sufficiently away from the resonance rotational speed in the case of a balancing rolling element used in a vertical washing machine. In this case, the position of the laundry and the position of the rolling element for balancing are in the same phase position, and even if the rotation speed is lower than the resonance rotation speed, the rotation speed in the vicinity of the resonance rotation speed is kept constant. It was made for the first time by finding out that the position of the rolling elements for balancing gathered at a position shifted from the in-phase position to the opposite-phase position side. In other words, in the case of the conventional fixed concept, in the case of a rolling element for rotational movement in a horizontal plane such as that used in a vertical washing machine, even if it is kept constant at any rotational speed lower than the resonant rotational speed, It was thought that it could only be collected in the same position as the laundry. For this reason, in order to prevent the maximum vibration due to the laundry and the balancing rolling elements gathering in the same phase position in the vicinity of the resonant rotational speed, it is sufficiently separated from the resonant rotational speed to collect the balancing rolling elements. In the past, it was thought that there was no choice but to collect at low speed. The present inventor has been able to conceive a configuration opposite to the conventional configuration only based on the new knowledge as described above.

  Furthermore, the inventor of the present application has also found that as the rotational speed of the drum maintained at a constant speed is made closer to the resonant rotational speed, the position where the balancing rolling elements gather linearly changes to the opposite phase position side. Accordingly, the rotation control unit is configured to keep the drum at a first rotation speed that is slightly lower than the resonance rotation speed for a certain period of time. It is possible to easily grasp the accurate position from the characteristic that the position also changes linearly. That is, according to the present invention, it is possible to accurately grasp the initial position of the balancing rolling element, which has been difficult in the conventional vertical washing machine, and to make the initial position close to the opposite phase position. It is also possible to move the balance rolling element to the opposite phase position with high accuracy in a short time. Therefore, it is possible to exceed the resonance rotational speed in a state where the amplitude of vibration is the smallest, and vibration can be greatly reduced.

  In order to move the balance rolling elements collected at the initial position to the opposite phase position in a short time without causing a large vibration in the drum, the rotation control unit sets the rotation speed of the drum at the first rotation speed. After maintaining for a certain time, the rotation speed of the drum is a second rotation speed that is lower than the resonance rotation speed, and a third rotation speed that is near or higher than the resonance rotation speed. The number of times the rotation speed of the drum is changed to the third rotation speed after the rotation speed of the drum is maintained at the first rotation speed for a certain period of time. In this case, it may be set based on the initial position which is the position of the balance rolling element with respect to the laundry.

  If this is the case, it is difficult to move the drum from the initial position to the opposite phase position even when the drum is rotated at a speed lower than the resonance rotational speed. By alternately changing the position, the balance rolling element can be gradually shifted to the opposite phase position side by the inertial force when the rotation speed is changed. Furthermore, since the third rotation speed is set to be close to the resonance rotation speed or higher than the resonance rotation speed, the amount of movement of the rolling elements for balancing can be increased, and the anti-phase can be achieved in a short time. It can be moved to a position. In addition, since the initial position of the balancing rolling element is accurately grasped, the number of times required to move the balancing rolling element to the opposite phase position can be accurately calculated, and the balance is accurately placed in the opposite phase position. The rolling element can be moved.

  To collect the rolling elements for balancing as close as possible to the opposite phase position, absorb the difference in resonance rotational speed due to machine manufacturing errors, etc., and prevent resonance from occurring when the first rotational speed is set. The first rotation speed may be set to 65% or more and 95% or less of the resonance rotation speed of the drum.

  An example of the more specific first rotation speed at which the effects as described above can be obtained includes one in which the first rotation speed is set to 28 rpm or more and 41 rpm or less.

  In order to move the balance rolling element to the opposite phase position in the shortest time while making the minimum number of speed changes, the circumferential direction of the balance rolling element when the rotation speed of the drum is the third rotation speed The number of times is set so that the product of the moving distance to the third rotational speed is approximately equal to the circumferential distance between the laundry and the balancing rolling element at the initial position. Anything is acceptable.

  In order to move the balancing rolling element to the opposite phase position so that the drum does not vibrate significantly when it is raised to the third rotational speed, the third rotational speed is What is necessary is just to set so that the vibration which arises may become below an allowable amplitude.

  Further, in order to reduce the vibration generated in the drum, the time for continuing the third rotation speed may be set so that the vibration generated in the drum is less than the allowable amplitude.

  As described above, according to the vertical washing machine of the present invention, before the drum is rotated at high speed, the drum is kept constant at a rotational speed slightly lower than the resonant rotational speed before rotating the drum at a rotational speed higher than the resonant rotational speed. In this state, the position of the rolling elements for balancing can be collected not at the in-phase position but at a position shifted from the in-phase position to the opposite-phase position side, and the position can be grasped substantially accurately. Accordingly, the balance rolling element can be started to move from a position close to the opposite phase position, and the amount of movement necessary to move the balance rolling element to the opposite phase position can be accurately determined, so that vibration is generated. Thus, the balance rolling element can be moved in a short time.

The schematic diagram which shows the vertical washing machine which concerns on one Embodiment of this invention. The schematic diagram which shows the change of the speed command profile and vibration amplitude of the rotation control part in the embodiment. The graph which shows the relationship between the magnitude | size of the 1st rotation speed in the same embodiment, and the phase difference of a laundry and a ball | bowl. The graph which shows the detail of the speed command and actual speed of the 3rd rotational speed in the embodiment. The graph which shows the comparison of the maximum amplitude of the transient vibration in the embodiment and a prior art example. The schematic diagram explaining the position where each ball | bowl gathers at the time of the stop in the ball balancer provided in the diagonal drum, and the ball balancer provided in the vertical drum. The schematic diagram which shows the movement aspect of each ball | bowl when a drum is rotated at the fixed rotational speed in the washing machine provided with the conventional diagonal drum. The graph which shows the profile of the drum rotational speed command in the conventional vertical washing machine.

  An embodiment of the present invention will be described with reference to the drawings.

  The washing machine of this embodiment is a vertical washing machine 100 in which the rotation axis of the drum 1 in which the laundry W is accommodated is set vertically as shown in FIG. When listing members related to the present invention, a motor, which is an electric motor for rotationally driving the drum 1, is provided at the lower part of the drum 1. A ball balancer 2 is provided that includes a ball 21 that moves in a direction to cancel the imbalance when an imbalance due to the bias of the laundry W occurs in the drum 1. The washing machine also includes a control mechanism for switching each selection process and controlling the rotation speed of the electric motor. The control mechanism is, for example, a so-called computer or microcomputer including a CPU, a memory, an input / output interface, and the like, and is configured to exhibit at least a function as the rotation control unit 4 for controlling the rotation speed of the drum 1. It is.

  Each part will be described in detail.

  The drum 1 has a substantially hollow cylindrical shape with an open upper surface, and its rotation axis (center axis) is set to be vertical. When washing or dehydration is performed by rotating the drum 1, the laundry W accommodated in the drum 1 may be biased. As a result, an eccentric load acts on the drum 1 and the drum 1 is swung around, which may increase vibration. The ball balancer 2 to be described later is for balancing the eccentric load applied to the drum 1 so as to reduce the whirling and suppress the vibration.

  The ball balancer 2 includes a substantially ring-shaped rail having a hollow inside formed at the upper surface side end portion of the drum 1 and a plurality of balls 21 (balance balance members) accommodated in the rail so as to be able to roll in the circumferential direction. Rolling elements). Since each ball 21 is configured to move only in the horizontal plane along the rail, the initial position of each ball 21 is not determined when the drum 1 is stopped. These balls 21 naturally move in a direction to cancel the unbalance due to the eccentric load, for example, by changing the rotation speed of the drum 1. In the present embodiment, each ball 21 not only waits for natural movement to the opposite phase position of the laundry W but also forcibly moves it.

  The said rotation control part 4 controls the rotational speed of the said drum 1 in a washing process or a spin-drying | dehydration process, for example. In particular, the rotation control unit 4 of the present embodiment can reduce vibration of the drum 1 by speed control when the drum 1 is shifted from a low rotation speed to a high rotation speed exceeding the resonance rotation speed of the drum 1. It is configured. More specifically, the rotation control unit 4 performs speed control by appropriately changing a speed command input to the electric motor, and changes the speed of the drum 1 from a low rotation speed to a high rotation speed. When changing, as shown in FIG. 3, the speed is changed in order in four modes of a low speed range speed increasing mode, a ball position estimation mode, a ball reciprocal position movement mode, and a high speed range speed increasing mode. It is.

  Hereinafter, the configuration and operation of the rotation control unit 4 in each mode will be described in detail.

  In the low speed region speed increase mode, the rotation control unit 4 until the rotation speed of the drum 1 reaches a first rotation speed that is a rotation speed slightly lower than the resonance rotation speed of the drum 1 (lower by a predetermined value). The rotational speed is increased substantially linearly. When the drum 1 is started, the position of each ball 21 is not fixed as shown in FIG. This is because each ball 21 is attached so as to be movable in a horizontal plane and is not affected by gravity with respect to the direction of motion, so that there is no bias.

  In the ball position estimation mode, the rotation control unit 4 is configured to maintain the rotation speed of the drum 1 at the first rotation speed for a predetermined time. As described above, when the first rotation speed, which is a speed in the vicinity of the resonance rotation speed, is maintained for a certain period of time, the balls 21 do not gather at the in-phase position with the laundry W as conventionally considered. The inventor of the present application has found that the light gathers at a position slightly shifted to the opposite-phase position side. Furthermore, as a result of earnest examination, as shown in the graph of the vibration phase representing the phase difference between the laundry W and the position of the ball 21 in FIG. 3, the position of each ball 21 movably attached in the horizontal plane is The position of the balls 21 gathers gradually from the in-phase position to the opposite-phase position side from a certain rotation speed, rather than discontinuously changing the position at the resonance rotation speed as previously considered. I found out. As can be seen from the graph of FIG. 3, the change in the position of the ball 21 changes approximately linearly within a predetermined speed range with respect to the magnitude of the rotational speed to be kept constant, and is set based on this graph and an expression representing the vibration phase. The set position of the balls 21 corresponding to the rotating speed can be calculated on a one-to-one basis. The position (phase difference) of the collection position of each ball 21 with respect to the laundry W is calculated in advance for each rotational speed, for example, and the position data is stored in a memory or the like in the control mechanism. The position of each ball 21 may be estimated by measuring the speed at which the drum 1 is actually rotating and sequentially calculating the position of each ball 21 based on the measured speed.

  In the present embodiment, the first rotation speed that is kept constant in the ball position estimation mode includes a speed at which a phase difference between the laundry W and each ball 21 starts to occur (20 rpm in the graph of FIG. 3), and a resonance rotation speed. (The speed is 43 rpm in the graph of FIG. 3). More precisely, the first difference between the speed at which the phase difference between the laundry W and each ball 21 is greater than or equal to a predetermined amount (20 ° or more in the graph of FIG. 3) (25 rpm in the graph of FIG. 3) and the resonance rotational speed. One rotation speed is set. The first rotation speed allows the variation of the resonance point due to a difference in the weight of the laundry W, a manufacturing error of each vertical washing machine 100, and the like so as not to exceed the resonance rotation speed. A rotational speed lower by a predetermined speed than the rotational speed is set. More specifically, in order to set a preferable first rotation speed regardless of the weight of the drum 1 or the laundry W, the first rotation speed is set to 65% or more and 95% or less of the resonance rotation speed. do it. In the present embodiment, it is preferable to set the first rotation speed at 28 rpm or more and 41 rpm or less. Note that when the first rotational speed is made as close as possible to the resonance rotational speed, the gathering position of the balls 21 gathers in a place close to the reciprocal position. The time taken to complete the process can be further reduced.

  In the ball reciprocal position movement mode after the balls 21 are gathered at a predetermined gathering position, the rotation control unit 4 applies a roughly pulse-like speed change to the drum 1 as shown in FIG. The position of the ball 21 is configured to move gradually to the opposite phase position. More specifically, the rotation control unit 4 sets the rotation speed of the drum 1 to a second rotation speed that is lower than the resonance rotation speed, and the vicinity of the resonance rotation speed or the resonance rotation speed. The third rotational speed, which is a rotational speed higher by a predetermined value, is alternately changed. Here, the second rotational speed is set to a rotational speed that is lower than the first rotational speed by a predetermined value. Further, the rotation control unit 4 is configured to input a pulse-shaped speed command to the electric motor so as to be the third rotation speed, and is generated when the rotation speed of the drum 1 approaches the resonance rotation speed. The number of pulses of the speed command and the pulse width are set so that the vibration has an allowable amplitude.

  Regarding the pulse width when the rotation control unit 4 inputs a speed command corresponding to the third rotation speed to the electric motor, the distance from the position of each ball 21 to the opposite phase position estimated in the ball position estimation mode. Is set to the number of times divided by the amount of movement of each ball 21 per pulse of the speed command. More specifically, since the equation of motion of each ball 21 is described as Equation (1), the movement amount per one pulse can be expressed as Equation (2).

Here, C: viscosity coefficient, τ: motor torque, I _b : inertia of the ball 21, t: pulse width, ω ₀ : initial rotation speed.

  The pulse height and pulse width of the speed command corresponding to the third rotation speed are set so that the actual speed of the drum 1 exceeds the resonance rotation speed for a very short time as shown in FIG. . More specifically, the pulse height of the speed command corresponding to the third rotation speed is set so that the actual rotation speed of the drum 1 is about ± 5% of the resonance rotation speed. The pulse width of the speed command is set so that the time during which the actual speed is within the resonance band is about 100 to 1000 msec. In this way, the rotational speed of the drum 1 can be adjusted so as to momentarily exceed the resonant rotational speed, and it is possible to prevent a large vibration from occurring.

  Further, the pulse interval of each pulse of the speed command corresponding to the third rotational speed is within 5% (in this example, within 2 rpm) of the difference between the actual rotational speed of the drum 1 and the speed command corresponding to the second rotational speed. Now, a speed command pulse corresponding to the next third rotational speed is given. The reason why pulses are applied in this manner is that each ball 21 cannot move when the interval is short, and a speed difference is generated between the leading ball 21 and the rear ball 21 and the balls 21 are scattered. In other words, after inputting a speed command pulse corresponding to the third rotational speed, by keeping constant at a second rotational speed lower than the resonant rotational speed, a new one is again made after each ball 21 has completely moved. It is possible to move the balls 21 in a state where the balls 21 are hardened by inputting various pulses. That is, each ball 21 can be moved to the opposite phase position in a state where the balls 21 are hardened, and the unbalance can be eliminated in a shorter time.

  Due to the rotation speed control of the drum 1 in the ball reciprocal position movement mode by the rotation control unit 4 as described above, the balls 1 are gathered between the laundry W and the reciprocal position in the ball position estimation mode as shown in FIG. Each ball 21 can be collected at the opposite phase position. That is, before the resonance frequency is constantly exceeded, the unbalance in the drum 1 can be eliminated.

  Finally, in the high speed range speed increasing mode, the rotation control is configured to linearly accelerate the rotation speed of the drum 1 from the second rotation speed to the target high speed rotation speed as shown in FIG. It is. In other words, after the unbalance of the eccentric load of the drum 1 is eliminated, the rotational speed of the drum 1 is increased by normal acceleration.

  The effect of reducing transient vibration, which is vibration generated when accelerating beyond the resonance rotational speed in the vertical washing machine 100 of the present embodiment configured as described above, will be described with reference to FIG. In FIG. 5, the maximum amplitude in the transient vibration of the present embodiment is indicated by a solid line, and as a comparative example, the maximum amplitude of the transient vibration in a conventional washing machine that does not perform the rotational speed control as in the present embodiment is indicated by a dotted line. In FIG. 5, the horizontal axis indicates the weight of the laundry W accommodated therein, and the vertical axis indicates the maximum amplitude in the transient vibration.

  As apparent from FIG. 5, when the present invention is used, the maximum amplitude of the transient vibration can be reduced to about 1/3 times regardless of the amount of the laundry W accommodated. As described above, before the resonance rotational speed is exceeded, each ball 21 is arranged in a reciprocal position with respect to the laundry W and is in the most balanced state. This is because the swing around can be reduced. In addition, when the quantity of the laundry W is 0, the difference does not appear because the ball balancer 2 itself is unbalanced in both washing machines when there is no opposite laundry W, and there is no difference. .

  As described above, according to the vertical washing machine 100 of the present embodiment, the balls 21 constituting the ball balancer 2 are placed between the in-phase position and the anti-phase position with respect to the laundry W in a state before exceeding the resonance rotational speed. Can be collected. In addition, the position of each collected ball 21 can be grasped substantially accurately based on the first rotational speed. For this reason, in the said ball reciprocal position movement mode, the movement amount which should move each ball | bowl 21 can be calculated correctly, and each ball | bowl 21 can be collected to a reciprocal position accurately in a short time. Furthermore, since each ball 21 can be collected in the opposite phase position with respect to the laundry W in a state before exceeding the resonance rotation speed, the resonance rotation speed can be exceeded in the state where the drum 1 is most balanced. The swing of the drum 1 can be dramatically reduced. Accordingly, the vibration amplitude and noise when shifting to high speed rotation can be greatly reduced as compared with the conventional vertical laundry.

  Other embodiments will be described.

  In the above embodiment, the balancing rolling element is a ball, but it may have any shape as long as it can roll in the circumferential direction. Further, in the rotation control, each ball is moved to the opposite phase position by inputting a pulsed speed command. However, a sudden speed change is generated in the drum by an input command having a remaining shape such as a triangular wave. It doesn't matter if you do. In addition to the above embodiment, a Hall IC for detecting the position of each ball, a MEMS sensor for detecting the magnitude of vibration, and the like may be provided. Control for suppressing vibration may be performed more strictly than when there is such a sensor, or for example, the magnitude of the first rotation speed may be appropriately tuned according to the output from each sensor. .

  In addition, various modifications and combinations of embodiments may be performed without departing from the spirit of the present invention.

100 ... vertical washing machine 1 ... drum 21 ... ball (rolling element for balance)
3 ... Electric motor (motor)
4 ... Rotation controller

Claims (7)

A drum that is rotatably supported around a vertical axis and is subjected to an eccentric load due to the bias of the laundry accommodated therein, an electric motor that rotationally drives the drum, and the drum can be rolled in the circumferential direction. A vertical washing machine comprising one or a plurality of balancing rolling elements that are attached and move in a direction that cancels the unbalance due to the eccentric load, and a rotation control unit that drives the electric motor to control the rotational speed of the drum Because
The rotation control unit is configured to increase a rotation speed higher than the resonance rotation speed after maintaining a first rotation speed that is slightly lower than the resonance rotation speed of the drum for a certain time. A vertical washing machine characterized by After the rotation control unit maintains the rotation speed of the drum at the first rotation speed for a certain period of time, the rotation speed of the drum is a second rotation speed that is lower than the resonance rotation speed, and the resonance It is configured to alternately change in the vicinity of the rotational speed or a third rotational speed that is a rotational speed higher than the resonance rotational speed,
The number of times the rotation speed of the drum is set to the third rotation speed is an initial position that is the position of the balancing rolling element with respect to the laundry after the drum rotation speed is maintained at the first rotation speed for a certain period of time. The vertical washing machine according to claim 1, wherein the vertical washing machine is set based on a position.   The vertical washing machine according to claim 1 or 2, wherein the first rotation speed is set to 65% or more and 95% or less of a resonance rotation speed of the drum.   The vertical washing machine according to claim 1, 2 or 3, wherein the first rotation speed is set to 28 rpm or more and 41 rpm or less.   The product of the movement distance in the circumferential direction of the rolling element for balancing when the rotation speed of the drum is the third rotation speed and the number of times to make the third rotation speed is the laundry and the laundry at the initial position. The vertical washing machine according to claim 4, wherein the number of times is set so as to be substantially equal to a circumferential distance of the balancing rolling element.   The vertical washing machine according to claim 4 or 5, wherein the third rotation speed is set so that vibrations generated in the drum are less than or equal to an allowable amplitude.   The vertical washing machine according to claim 4, 5 or 6, wherein time for continuing the third rotation speed is set so that vibration generated in the drum is less than or equal to an allowable amplitude.