JP2010125236A - Washing machine having ball balancer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a ball balancer system surely operate even if an eccentric load changes at a high rotating speed while having a simple and inexpensive constitution in a washing machine or the like which is constituted in such a manner that the eccentric load applied to a drum may be negated by using a ball balancer system. <P>SOLUTION: In the water repulsion process, a controlling means 8 raises the rotating speed of the drum 3 to a second rotating speed which exceeds the resonance rotating speed by a certain degree or higher, and then, makes the rotating speed of the drum 3 to a first rotating speed in a vicinity of the resonance rotating speed of the drum 3. After keeping the first rotating speed for a specified period of time, the rotating speed is raised again. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a washing machine having a ball balancer system capable of suppressing drum vibration during dehydration.

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

  Conventionally, a liquid balancer has been used to correct this imbalance. However, since the liquid has a small specific gravity and its effect is limited, this liquid balancer is a ball balancer in which the cancel range of unbalance is expanded by replacing the liquid with a metal ball having a large specific gravity (Patent Document 1).

Such a ball balancer system (see FIG. 1) is an imbalance that generates an eccentric load by arranging a plurality of balls having degrees of freedom in the rotational direction (circumferential direction) in a tubular race portion attached to the inner periphery of the drum. This is a system that uses a dynamic phenomenon in which a ball automatically moves to an opposing position with respect to a body (here, laundry (cloth)). FIG. 1 shows an example of a double ball balancer in which rolling elements such as a plurality of metal balls (hereinafter also referred to as balls) are arranged at two locations on the front end portion and the rear end portion of the drum. In addition, a single ball balancer in which a metal ball is arranged at one place on the drum is also known, and these are the same in principle. That is, the ball balancer system is characterized in that a plurality of balls can change their positions and automatically correct the imbalance in response to the cloth imbalance amount that changes with time during the dehydration process.
JP 10-43475 A

  By the way, the ball balancer system has a disadvantage that the automatic unbalance correction function is lost when the rotational speed exceeds a certain upper limit value. In other words, when the frictional force due to the centrifugal force increases and reaches a rotational speed at which the ball is stopped in the race member, the position of the ball cannot be changed, and the ball balancer system does not function.

  Therefore, normally, it is set so that the ball reaches the unbalance correction position before the rotation speed reaches the upper limit value. If there is an imbalance, such as a disk drive device, but it is fixed depending on the mechanism and does not change over time, if it is set in this way, it will be corrected temporarily Later, even if the rotational speed further increases and exceeds the upper limit, there is no inconvenience because the unbalance has already been corrected.

  However, the situation is different when this ball balancer system is applied to a washing machine. In a washing machine, in the process of dehydrating a water-containing cloth, the water content varies depending on the quality of the cloth, so the amount of imbalance changes with the passage of time and usually increases. For example, it is the most extreme example when synthetic fibers and cotton are attached to the counter electrode in the circumferential direction. Because the amount of dehydration from the cotton is large, the balance is lost over time. In addition to the above-described difference in the dehydration rate, for example, an unbalanced change in the amount of unbalance can sufficiently occur even when the laundry is moved unexpectedly.

  As a result, when the rotation speed for dehydration is higher than the upper limit value at which the ball balancer system functions, even if the balance is compensated by the ball balancer system at the initial stage, the balance described above during dehydration The ball balancer system cannot respond to changes. This is because the rotational speed is higher than the upper limit value at this time, and the function is stopped. Therefore, there is a problem that a phenomenon that the dehydration vibration becomes large from the middle or the magnitude of the vibration varies occurs. This problem can also occur with a single dehydrator.

  The present invention has been made in view of such problems, and in a washing machine or the like configured to cancel the eccentric load acting on the drum using a ball balancer system, while having a simple and inexpensive configuration, Even if the eccentric load changes at a high rotation speed, the ball balancer system can be reliably operated.

  That is, the washing machine according to claim 1 of the present invention is configured to be capable of rotating in the circumferential direction around the drum, which is configured to store and rotate the laundry around a predetermined rotation axis, the electric motor that rotates the drum, and the drum. One or a plurality of balancing rolling elements that are attached and move in a direction to cancel the unbalance due to the laundry, and a control means that drives the electric motor to control the rotational speed of the drum, It further comprises vibration detecting means for detecting the vibration of the drum, and in the dehydration step, when the control means increases the rotational speed of the drum to exceed the resonance rotational speed above a certain value, the vibration detecting means performs a certain value or more. Is detected, the drum rotation speed is lowered to a first rotation speed that is close to the resonance rotation speed, the first rotation speed is maintained for a certain period of time, and then the rotation speed is again detected. It is characterized in that the raising.

  According to a second aspect of the present invention, there is provided a washing machine comprising: a drum that stores and rotates laundry around a predetermined rotation axis; an electric motor that rotationally drives the drum; and a drum that is rotatable in the circumferential direction. One or a plurality of balancing rolling elements that are attached and move in a direction to cancel the unbalance due to the laundry, and a control means that drives the electric motor to control the rotational speed of the drum, In the dehydration step, the control means increases the rotation speed of the drum to a second rotation speed that exceeds the resonance rotation speed by a certain amount, and then decreases the rotation speed to a first rotation speed that is in the vicinity of the resonance rotation speed of the drum. The first rotation speed is maintained for a certain time, and then the rotation speed is increased again.

  If this is the case, even if an imbalance occurs at the second rotational speed at which the rolling element cannot move, the rotational speed of the drum is reduced to the first rotational speed in the vicinity of the resonant rotational speed without greatly reducing the rotational speed of the drum. Thus, the rolling element can be moved to the balance compensation position using the vibration at that time to return to the balance state.

  A dehydrator according to a third aspect of the present invention is a drum that accommodates and rotates an object to be dehydrated around a predetermined rotation axis, an electric motor that rotationally drives the drum, and a drum that is rotatably attached to the drum. And one or a plurality of balancing rolling elements that move in a direction to cancel the unbalance due to the object to be dehydrated, and a control means that drives the electric motor to control the rotational speed of the drum, It further comprises vibration detecting means for detecting the vibration of the drum, and in the dehydration step, when the control means increases the rotational speed of the drum to exceed the resonance rotational speed above a certain value, the vibration detecting means performs a certain value or more. Is detected, the rotational speed of the drum is lowered to a first rotational speed that is close to the resonant rotational speed, the first rotational speed is maintained for a certain period of time, and then the rotational speed is again measured. It is characterized in that the raising.

A dehydrator according to a fourth aspect of the present invention is a drum that accommodates and rotates an object to be dehydrated around a predetermined rotation axis, an electric motor that rotationally drives the drum, and a drum that is rotatably mounted on the drum. And one or a plurality of balancing rolling elements that move in a direction to cancel the unbalance due to the object to be dehydrated, and a control means that drives the electric motor to control the rotational speed of the drum, In the dehydration step, the control means increases the rotation speed of the drum to a second rotation speed that exceeds the resonance rotation speed by a certain amount, and then decreases the rotation speed to a first rotation speed that is in the vicinity of the resonance rotation speed of the drum. The first rotation speed is maintained for a certain time, and then the rotation speed is increased again.
Even with such a dehydrator, the same action as the washing machine can be achieved.

According to the washing machine or the dehydrator according to the present invention configured as described above, as described above, at the second rotation speed at which the rolling element cannot move, for example, a change in the balance state due to the dehydration occurs, and an unexpected imbalance occurs. Even if the rotation speed of the drum is not lowered significantly, it is only lowered to the first rotation speed that is close to the resonance rotation speed, and the rolling element is moved to the balance compensation position using the vibration at that time. It can be returned to the state.
Therefore, not only noise and vibration can be suitably suppressed, but also when maintaining the balance state during dehydration, the rotational speed is not greatly reduced, so that it does not take a long time for acceleration and deceleration, and There is no major obstacle to the dehydration function.

  Furthermore, since the parameter for suppressing vibration and noise can be limited to only the rotational speed, this can be realized only by setting the rotational speed profile. In other words, it can be easily realized with the existing equipment configuration using low-cost control means without requiring dedicated equipment such as new sensors or complicated software, so as to suppress the increase in price as much as possible. Can do.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 2 is a longitudinal sectional view showing a schematic internal structure of the drum type washing machine 100 according to the present embodiment. In the figure, reference numeral 1 denotes a hollow body, and on the use end side (hereinafter also referred to as the front side) of the body 1, an insertion port 11 for introducing laundry 9 (shown in FIG. 3), An openable / closable lid 12 is provided for closing the insertion port 11. Further, a water tank 2 is disposed inside the body 1, and a drum 3 is provided further inside the water tank 2.

  The water tank 2 has a substantially cylindrical shape in which the rear end surface is closed by the bottom plate 21 and the front end portion is open. The center axis C is inclined from the horizontal or horizontal, and the front side is slightly higher than the rear side. The damper D and the elastic body S are supported so as to be swingable.

  The drum 3 has a cylindrical shape that is slightly smaller than the water tank 2. Like the water tank 2, the rear end face is closed by the bottom plate 31 and the front end face is open. The drum 3 is provided with a large number of holes 33 penetrating in the thickness direction, so that water can enter the drum 3 from the water tank 2 through the holes 33.

  A ball balancer system 7 is added to the front end portion and the rear end portion of the drum 3. The ball balancer system 7 includes a tubular guide member 71 that is mounted around the side periphery of the drum 3 and a plurality of rolling elements that are fitted into the guide member 71 without rolling and are rolled. It consists of a metal ball 72. As shown in FIG. 3, a viscous fluid 73 such as oil for suppressing a rapid movement of the ball 72 is stored inside the guide member 71.

  On the outside of the bottom plate 21 in the water tank 2, for example, an electric motor 4 for rotationally driving the drum 3 is attached. A rotating shaft 41 of the electric motor 4 passes through the bottom plate 21 through a bearing 42, and the drum 3 The bottom plate 32 is fixed.

  In addition, the code | symbol 5 shown in FIG. 2 is the water supply mechanism 5 which supplies wash water, and the code | symbol 6 is a drainage mechanism for discharging the wash water in the water tank 2 and the drum 3 outside.

  In addition to these configurations, the washing machine 100 controls the rotational speed of the electric motor 4 and the like, and calculates the weight of the laundry 9 in the drum, thereby automatically performing the washing process and the dehydrating process. 8 is provided at an appropriate location inside the body 1.

  This control means 8 is an electric circuit having a CPU, a memory, an I / O channel, an AD converter, various driver circuits, and the like as a hardware configuration, and the CPU and peripheral devices are in accordance with a program stored in the memory. Various functions are demonstrated by cooperation.

  The feature of this embodiment lies in the control of the rotational speed of the drum in the dehydration process by the control means 8. The control operation will be described below.

  The control means 8 first calculates the resonance rotational speed of the drum 3. The resonance rotational speed can be calculated by a known mathematical formula from the drum weight, the drum inner diameter, the spring constant, the damper constant, and the like. In addition, transient vibration occurs in a rotation speed region over a certain vertical range in the vicinity of the theoretical resonance rotation speed obtained by the above formula. Therefore, the control means 8 also determines the transient vibration rotation speed region by adding a vertical width to the theoretical resonance rotation speed. This region width is determined in advance so that the vibration obtained in advance by experiments and simulations is a region width that is not less than the vibration that cannot be ignored in the product specifications. Such a resonance rotation speed and transient vibration rotation speed region may be calculated separately and stored in the memory in advance, instead of being calculated by the control means 8.

  When the dehydration process is started, the control means 8 gradually increases the rotation speed of the drum 3 from the stopped state, and increases it to a higher predetermined second rotation speed beyond the transient vibration rotation speed region. The rotation speed is obtained by an output from a rotation speed sensor (not shown) attached to the electric motor 4, for example. This rotational speed sensor uses, for example, a Hall IC, but other methods may be used.

  Next, the rotational speed of the drum 3 is decreased from the second rotational speed to a first rotational speed that is slightly higher than the resonant rotational speed, specifically, the upper limit rotational speed in the transient vibration rotational speed region, and the first rotational speed is reduced. After maintaining for a certain time, the rotational speed is increased again to the final dehydrating rotational speed.

As a result, the vibration of the drum 3 in the dehydration process, in particular, the unexpected vibration generated at the rotational speed exceeding the transient vibration rotational speed region can be suppressed as much as possible.
Next, the reason will be described in detail.

After the dehydration process proceeds and passes through the resonance rotational speed of the rotating system, the ball 72 naturally moves to the position opposite to the laundry 9 which is an unbalanced body for the purpose of mechanical stability (basic operation of the ball balancer). ). However, due to the rolling friction moment (M _r ) of the ball 72, the movement of the ball 72 may stop without moving to the ideal unbalanced opposing position. The condition for preventing such a stop and urging the movement is when the equation (Equation 1) is established in relation to the axial displacement amount H of the speed.
The left side of this equation is a rolling friction moment, and the right side is a movement moment that promotes movement.

The axial displacement amount H is a function of the speed (ω), and the resonance rotational speed (ω _n ) is _expressed by the equation (Equation 2).
FIG. 4 is a graph showing the change in the value of H.

Since the rolling friction moment _Mr is a function of the centrifugal force, the equation (Equation 3) is obtained.

Therefore, Expression (Expression 4) is derived from Expression (Expression 1), (Expression 2), and (Expression 3).

Encouraging the movement of the ball 72 is to increase the right side of the equation (Equation 4), that is, the value of H. As shown in FIG. 4, the rotational speed (ω) is changed to the resonant rotational speed (ω _n ). To get closer. However, if the rotational speed (ω) is too close to the resonant rotational speed (ω _n ) and lowered to the transient vibration rotational speed region, vibration in this transient region becomes significant, which is preferable in terms of product specifications. is not.

  Ultimately, the target rotational speed to be decelerated in order to promote the movement of the ball 72, that is, the first rotational speed is most preferably slightly higher than the resonance rotational speed, more specifically, just above the upper limit of the transient vibration rotational speed region. It will be.

  The first rotational speed is determined as described above, and the dehydration maintenance speed immediately before that is determined by the intermediate speed of the process and the rotational speed at which the dehydration rate reaches 60 to 80% and the maintenance time thereof. That's fine.

It is not necessary to decelerate regardless of the balance at the second rotational speed, so decelerate after detecting whether the vibration level at this speed is above a certain level determined from the product specifications. Alternatively, it may be determined whether to decelerate. The vibration detection means for this purpose is as follows.
1) An acceleration sensor directly attached to the drum 3 or the water tank 2 or the like.
2) Means for detecting the current of the drive motor and estimating and detecting torque vibration from the torque current calculated from the current.
3) Means for detecting from the magnitude of vibration obtained by time differentiation of the speed calculation result of the rotation speed sensor.

Next, FIG. 5 shows an example of a velocity profile for suppressing steady vibration.
Here, the drum rotation speed is maintained at 500 rpm exceeding the transient vibration rotation speed region for about 40 seconds, and immediately after the dehydration rate reaches 60 to 80%, the unbalance amount is determined by the vibration sensor, motor drive current, motor speed. If it is detected based on the amplitude of the vibration and judged to be unacceptable vibration, it is decelerated to the first rotation speed (speed 280 rpm slightly higher than the resonance rotation speed in the figure) and maintained for 10 seconds, and the operation for correcting the imbalance is performed ing.

  The first rotational speed is a speed having a vibration displacement that allows the ball 72 to move most as described above. FIG. 6 shows the relationship between various target deceleration speeds (first rotation speeds) and vibrations. In this example, the resonance region (transient vibration rotation speed region) is widened to 205 to 240 rpm, and the deceleration speed is set to 270 to 360 rpm on the resonance region and compared. It can be seen from FIG. 6 that the movement cannot be sufficiently promoted. Therefore, a conclusion of 300 rpm or less is derived in this example.

  After that, the normal dehydration process is entered as shown in FIG. 5, but when the change before and after the magnitude of vibration is compared at 500 rpm in the middle, the vibration width is about as apparent from the Lissajous figure described above. It turns out that it is about 1/4. Thus, the imbalance that changes every moment depending on the cloth quality can be canceled in the region of 500 rpm or less.

  That is, according to the present embodiment, even if the balance state changes due to, for example, dehydration at the second rotational speed, and the unexpected unbalance occurs, the rotational speed of the drum 3 is not greatly reduced. The ball 72 can be moved to the balance compensation position and returned to the balance state by using the vibration at that time simply by dropping to the first rotation speed that is in the vicinity.

  Therefore, not only noise and vibration can be suitably suppressed, but also when maintaining the balance state during dehydration, the rotational speed is not greatly reduced, so that it does not take a long time for acceleration and deceleration, and There is no major obstacle to the dehydration function.

  Furthermore, since the parameter for suppressing vibration and noise can be limited to only the rotational speed, this can be realized only by setting the rotational speed profile. In other words, it can be easily realized with the existing equipment configuration using low-cost control means without requiring dedicated equipment such as new sensors or complicated software, so as to suppress the increase in price as much as possible. Can do.

  The present invention is not limited to the illustrated example. For example, the present invention can be applied to a washing machine having a vertical drum (rotating axis is vertical), and the same effect can be obtained by applying the present invention to a dehydrator. In addition, it goes without saying that the present invention can be variously modified without departing from the spirit of the present invention.

The typical internal structure figure which shows an example of a ball balancer system. The typical longitudinal section showing the internal structure of the washing machine in one embodiment of the present invention. The typical internal structure figure seen from the axial direction which shows the ball balancer system in the embodiment. The analysis graph which shows the relationship between the vibration and rotation speed in the same embodiment. The speed profile example for suppressing the transient vibration in the embodiment. The correlation graph which shows the correlation of the rotational speed and vibration in the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Washing machine C ... Rotary shaft 3 ... Drum 4 ... Electric motor 71 ... Guide member 72 ... Rolling body for balance (ball)
8 ... Control means

Claims (4)

A drum that accommodates and rotates laundry around a predetermined rotation axis, an electric motor that rotationally drives the drum, and is attached to the drum so as to be able to roll in the circumferential direction, and moves in a direction to cancel the imbalance caused by the laundry. A washing machine comprising one or a plurality of balancing rolling elements and a control means for controlling the rotational speed of the drum by driving the electric motor,
Further comprising vibration detecting means for detecting vibration of the drum,
In the dehydration step, when the control means raises the rotational speed of the drum beyond the resonance rotational speed above a certain level, if the vibration detecting means detects a vibration above a certain level, the rotational speed of the drum is increased. The washing machine is characterized in that it is lowered to a first rotational speed that is in the vicinity of the resonant rotational speed, maintained at the first rotational speed for a certain period of time, and then the rotational speed is increased again. A drum that accommodates and rotates laundry around a predetermined rotation axis, an electric motor that rotationally drives the drum, and is attached to the drum so as to be able to roll in the circumferential direction, and moves in a direction to cancel the imbalance caused by the laundry. A washing machine comprising one or a plurality of balancing rolling elements and a control means for controlling the rotational speed of the drum by driving the electric motor,
In the dehydration step, the control means increases the rotation speed of the drum to a second rotation speed that exceeds the resonance rotation speed by a certain amount, and then decreases the rotation speed to a first rotation speed that is in the vicinity of the resonance rotation speed of the drum. The washing machine is characterized in that after maintaining the first rotation speed for a certain time, the rotation speed is increased again. A drum that accommodates and rotates a dewatering object around a predetermined rotation axis, an electric motor that rotates the drum, and a direction that is rotatably attached to the drum in a circumferential direction so as to cancel the imbalance due to the dewatering object A dehydrator comprising one or a plurality of balancing rolling elements that are moved to and a control means that drives the electric motor to control the rotational speed of the drum,
Further comprising vibration detecting means for detecting vibration of the drum,
When the control means increases the drum rotation speed exceeding the resonance rotation speed above a certain level, and the vibration detection means detects a vibration above a certain level, the rotation speed of the drum is changed to the resonance rotation speed. A dehydrator, wherein the dehydrator is lowered to a first rotation speed that is in the vicinity, maintained at the first rotation speed for a predetermined time, and then increased again. A drum that accommodates and rotates a dewatering object around a predetermined rotation axis, an electric motor that rotates the drum, and a direction that is rotatably attached to the drum in a circumferential direction so as to cancel the imbalance due to the dewatering object A dehydrator comprising one or a plurality of balancing rolling elements that are moved to and a control means that drives the electric motor to control the rotational speed of the drum,
The control means raises the rotational speed of the drum to a second rotational speed that exceeds the resonance rotational speed by a certain value, and then lowers it to a first rotational speed that is close to the resonant rotational speed of the drum. A dehydrator characterized by maintaining the rotation speed for a certain time and then increasing the rotation speed again.