JPH10216391A - Drum type washing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lessen unbalance of clothing which causes vibration and to realize reduction of vibration by providing plural steps of rotating a drum at a rotating speed lower than the rotating speed for dewatering before the drum reaches a designated rotating speed for dewatering, and controlling in such a manner that in one step among the above, the rotating speed becomes lower than that in the preceding step. SOLUTION: As shown in a timechart of the figure, before reaching a designated rotating speed N0 for dewatering, a spinning tub repeats normal rotation at 50rpm, stopping, reversion and stopping several times, and then rotates at such a rotating speed N1 that washing sticks to the inner peripheral surface thereof. Next, the rotating speed is reduced to such a rotating speed N2 that the centrifugal force is balanced with the center of gravity in inner peripheral radius position of washing put in the ideal state of uniformly sticking to the inner peripheral surface. Thus, washing in the unbalanced part has a smaller radius of rotation, so that only the washing of the unbalanced part drops repeatedly, thereby untangling the washing. Finally the radius of rotation balancing with the center of gravity can be attained to uniform the washing. After the rotation at the rotating speed N2 for designated time, it transits to designated rotating speed N0 for dewatering.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drum type washing machine, and more particularly to a technique for reducing imbalance of laundry during a spin-drying process.

[0002]

2. Description of the Related Art As a conventional drum type washing machine, for example, there is one as shown in FIG. In FIG. 1, reference numeral 1 denotes an outer box, and a water tank 2 supported by a suspension 4 is provided in the outer box 1, and a washing and dewatering drum 3 rotatably supported on a horizontal axis is provided in the water tank 2. Is provided. Aquarium 2
A drive motor 5 is attached to the lower side, and the rotation of the drive motor 5 is transmitted to the washing and dewatering drum 3 via a pulley, a belt, and the like (not shown).

During the spin-drying operation, the washing and spinning drum 3 is rotated at a predetermined spinning speed N ₀ by the drive motor 5, and the laundry 6 is washed by the centrifugal force.
Dewatering is performed by pressing against the inner peripheral surface of the. At this time,
It is rare that the laundry 6 is uniformly distributed on the inner peripheral surface of the washing and dewatering drum 3, and the laundry 6 causes an unbalance portion. The centrifugal force of the unbalanced portion causes vibration, the water tank 2 vibrates, and the main body vibrates through a vibration transmission path such as the suspension 4. As described above, in the drum type washing machine in which the washing and dewatering drum 3 rotates about the horizontal axis with respect to the floor surface 7, when the imbalance of the laundry 6 occurs during dehydration, the water tub 2 is perpendicular to the floor surface 7. Vibrates in plane. For this reason, compared with a washing machine in which a dehydration tub rotates around a vertical axis (a two-tub washing machine, a spiral type fully automatic washing machine, etc.), the vibration transmitting force to the floor 7 is large, and a drum washing machine is used. May require floor reinforcement. In addition, low vibration has been raised as one of the important issues of the drum type washing machine, for example, the body becomes large due to large vibration, and the body weight is increased to suppress vibration. As the most effective means for reducing the body vibration, a predetermined dehydration rotation speed N ₀
It is conceivable to minimize the imbalance of the laundry 6 that causes vibration before reaching.

On the other hand, there is a conventional technique disclosed in FIGS. 9 and 10 and Japanese Patent Application Laid-Open No. 54-18163. Explaining this prior art, when the washing and dewatering drum 3 before the dehydration rotation is stopped, as shown in FIG. 9, the laundry 6 is in a state of being accumulated below, and the predetermined dehydration rotation speed N ₀ is maintained as it is. , The laundry 6 is likely to remain in an unbalanced state, resulting in a large imbalance. Therefore, as shown in the time chart of FIG. 10, a loosening process is provided. First, in order to loosen the entanglement of the laundry 6, the washing and dewatering drum 3 is repeatedly rotated forward, inverting and stopping several times at about 50 rpm. Next, the washing and dewatering drum 3 is rotated at a rotation speed N _P at which the centrifugal acceleration (= R · ω ² ) substantially balances the gravity, and after a predetermined time, the washing and dewatering rotation speed N ₀ is reached, and a predetermined dehydration rotation is performed. Before reaching, the imbalance of the laundry 6 is minimized.

[0005]

However, in such a conventional method of controlling dehydration of a drum type washing machine,
At the rotation speed N _P , the laundry 6 is
The rotation of the laundry 6 upward and downward is greatly different because the load of the drive motor 5 when rotating the laundry 6 upward and downward is large. For this reason, the rotation speed (rotational angular velocity ω _1U ) when rotating the laundry 6 upward is slightly lower than the rotation speed (rotational angular velocity ω _1D ) when rotating the laundry 6 downward (ω _1U <ω <ω _1D). ), The centrifugal acceleration tends to be smaller than gravity. Further, as shown in FIG. 9, since the laundry 6 is collected below, the centrifugal acceleration due to the rotation of the washing and dewatering drum 3 is small near the center of the laundry 6, and the laundry is not lifted upward. It only rotates below the dewatering drum 3. From the above, the laundry 6 does not stick to the inner peripheral surface of the washing and dewatering drum 3 even though the rotation speed is such that the centrifugal acceleration due to the rotation of the washing and dewatering drum 3 and the gravity are balanced. 1
In the state shown in FIG. 1A, the imbalance of the laundry 6 in the portion A is likely to occur at a predetermined spinning speed N ₀ . Also, when the rotation speed is N _{P, the} laundry 6 is washed and the dehydration drum 3 is washed.
In order for the laundry 6 to be stuck to the inner peripheral surface, the rotation speed N _P needs to be set to a rotation speed having a centrifugal acceleration larger than gravity due to the above-mentioned phenomenon when the laundry 6 is accumulated below. And a radius Ri ₂ shown in FIG.
, The centrifugal acceleration and gravity balance (Ri ₂ · ω ² = g).
Problems result, that since the laundry 6 in radius Ri ₂ or more is the distribution as shown in Figure stick to the inner peripheral surface of the washing and dewatering drum 3 11 (b), the unbalance portion such as a B section remains There was a point.

[0006] The present invention has been made in view of the above,
An object of the present invention is to provide a drum-type washing machine capable of reducing the unbalance of laundry, which causes vibration, and realizing low vibration before the spinning process at a predetermined spinning speed.

[0007]

According to a first aspect of the present invention, there is provided a washing and dewatering drum, which is designed so that when the laundry is dehydrated in a washing and dehydrating drum, the rotation of the laundry before reaching a predetermined dehydration speed is performed. A plurality of stages each of which is rotated at a rotation speed lower than the dehydration rotation speed of the dehydration rotation speed, and at least one of the plurality of stages is controlled to have a stage in which the rotation speed is lower than the rotation speed of the previous stage. It is the gist to have. With this configuration, if there is an unbalanced portion of the laundry stuck to the inner peripheral surface of the washing and dewatering drum at the rotation speed in the previous stage, the laundry in the unbalanced portion will rise upward at the rotation speed in the stage where the rotation speed decreases. Rise and fall repeatedly. By repeating this, the unbalanced laundry is loosened,
Before the spinning operation at a predetermined spinning speed, the laundry can be washed and stuck uniformly on the inner peripheral surface of the spinning drum to reduce the unbalanced portion.

According to a second aspect of the present invention, in the drum type washing machine according to the _{first aspect} , the rotational speed at the preceding stage is N ₁ , the rotational speed at the stage at which the rotational speed decreases is N ₂ , and the rotational speed is N ₂ . The centrifugal force at the average inner radius of the laundry stuck to the inner peripheral surface of the washing and dewatering drum at ₁ o'clock was CF ₁ , and the laundry was stuck to the inner peripheral surface of the washing and dewatering drum at the rotation speed N ₂ . Assuming that the centrifugal force at the average inner radius of the laundry is CF ₂ and the gravity constant is G, CF ₁ > 1 G and CF ₂ ≦ 1 G
The gist is that With this configuration, the rotation speed N ₁
Sometimes the laundry is stuck to the inner peripheral surface of the washing and dewatering drum, and if there is an unbalanced portion of the laundry in this stuck state, only the unbalanced portion of the laundry at the rotation speed N ₂ has a gravity near the upper portion. Fall under the influence. As a result, the laundry is uniformly attached to the inner peripheral surface of the washing and dewatering drum, and the unbalanced portion is reduced.

According to a third aspect of the present invention, in the drum-type washing machine according to the first or second aspect, the rotational speed N _{1 in the} preceding stage and the rotational speed N _{2 in the} stage in which the rotational speed decreases are set to the values of the laundry. The gist is to determine the amount. With this configuration, the inner radius of the laundry when the laundry is uniformly attached to the inner peripheral surface of the washing and dewatering drum varies depending on the amount of the laundry. When the amount of laundry is large, the inner radius is small, and when the amount of laundry is small, the inner radius is large. Therefore, when the amount of the laundry is large, the rotation speeds N ₁ and N ₂ are increased by an amount corresponding to the small inner radius of the laundry so as to balance the gravity at the inner radius position, and when the amount of the laundry is small, Conversely, the rotational speeds N ₁ and N ₂ are reduced. Thereby, it is possible to stably reduce the imbalance of the laundry.

According to a fourth aspect of the present invention, in the drum-type washing machine according to the first or second aspect, the rotational speed N _{1 in the} preceding stage and the rotational speed N _{2 in the} stage in which the rotational speed decreases are set to the values of the laundry. The gist is to determine according to the fabric quality. With this configuration, the inner radius of the laundry when the laundry is uniformly attached to the inner peripheral surface of the washing and dewatering drum is different depending on the quality of the laundry. The harder the cloth, the smaller its inner radius, and the softer the cloth, the larger its inner radius. Therefore, when the laundry is hard, the rotation speeds N ₁ and N ₂ are increased by an amount corresponding to the small inner radius of the laundry so that the inner radius position of the laundry is balanced with gravity, and the laundry is soft. At times, the rotation speeds N ₁ and N ₂ are reduced. Thereby, it is possible to stably reduce the imbalance of the laundry.

According to a fifth aspect of the present invention, in the drum type washing machine according to the first or second aspect, a load torque of a motor for driving the washing and dewatering drum at a rotation speed N ₂ at a stage where the rotation speed decreases. Accordingly, the gist of the present invention is to detect the imbalance of the laundry in the washing and dewatering drum. With this configuration, if the laundry unbalance is large, the rotation unevenness in one rotation of the washing and dewatering drum becomes large, and the load torque of the drive motor differs between a large unbalanced state and a small unbalanced state. Therefore, it is possible to reliably detect a state in which the laundry is unbalanced by the load torque of the drive motor.

According to a sixth aspect of the present invention, in the drum type washing machine according to the first or second aspect, the rotation speed N ₁ at the preceding stage and the rotation speed N ₂ at the stage at which the rotation speed decreases are respectively described. The gist of the present invention is to detect the imbalance of the laundry in the washing and dewatering drum based on the difference in the load torque of the motor that drives the washing and dewatering drum. With this configuration, the load torque of the drive motor at the rotation speed N ₁ and
When comparing the load torque of the drive motor o'clock rotational speed N _2, towards the load torque of the rotational speed N ₂ o'clock drive motor falling laundry if unbalanced condition occurs it is increased. Therefore, the difference in load torque o'clock rotational speed N ₁ and the rotational speed N ₂ o'clock drive motor, a state unbalance is larger laundry makes it possible to detect more surely.

According to a seventh aspect of the present invention, in the drum type washing machine according to the fifth or sixth aspect, the stages of the number of revolutions N ₁ and the number of stages of the number of revolutions N ₂ are performed until a predetermined imbalance is achieved. The point is to repeat. With this configuration, the unbalanced state of the laundry can be reliably reduced to a predetermined amount or less by repeating the operation at the rotation speeds N ₁ and N ₂ .

According to an eighth aspect of the present invention, there is provided the drum type washing machine according to the seventh aspect, wherein the rotation speed N ₁ and the rotation speed N are set when the predetermined imbalance is not achieved.
₂ is increased by a predetermined amount, and the predetermined spin speed N ₀ is reduced by a predetermined amount. With this configuration, by increasing the rotation speeds N ₁ and N ₂ , the inner radius of rotation of the laundry, which is in proportion to gravity, becomes smaller, and the laundry is pressed more strongly against the inner peripheral surface of the washing and dewatering drum, and a predetermined dehydration is performed. By reducing the number of revolutions N ₀ , the occurrence of vibrations is suppressed, and the situation where the imbalance does not fall below the predetermined imbalance can be better solved.

[0015]

FIG. 1 is a block diagram showing an embodiment of the present invention.
7 will be described with reference to FIG. In FIG. 1, components that are the same as or equivalent to those in FIG. 8 are denoted by the same reference numerals as those described above, and redundant description will be omitted. First, the configuration of a drum-type washing machine will be described with reference to FIG. 1. In the present embodiment, a control circuit as control means for controlling the number of revolutions of the washing and dewatering drum 3 is provided below the outer box 1. The drive motor 5 is provided with a rotation sensor (not shown) for detecting the rotation speed of the output shaft. In addition, a key input unit (not shown) for performing key input and the like described below, a display, and the like are provided on an upper portion of the front surface of the outer box 1. FIG. 2 shows a control system. The control circuit 10 includes a calculation unit 11, a storage unit 12, a control unit 13, and a counter unit 14; an input signal 15 for keys and switches; And a motor load current signal 17 are input. The control circuit 10
Controls the drive motor 5 via the drive circuit 18 and controls the display operation of the display 19.

Next, each control method and operation will be described in order.

Before reaching a predetermined dehydration rotation speed N ₀ , two stages of rotation speeds N ₁ and N ₁ lower than the dehydration rotation speed N _0.
2 (N ₁ > N ₂ ). As shown in the time chart of FIG. 3, before reaching the predetermined spin-drying speed N ₀ , the washing and spin-drying drum 3 is moved five times to loosen the entanglement of the laundry 6.
After the forward rotation / stop / reversal / stop is repeated several times at 0 rpm, the laundry 6 is rotated at a rotation speed N ₁ at which the laundry 6 can be stuck to the inner peripheral surface of the washing / dehydrating drum 3. For rotating at a rotational speed N ₁ from a state where the laundry 6 at stop is biased downward, it is necessary to exert a great centrifugal force sufficiently than gravity, as mentioned in the prior art, the rotational speed N ₁ Sometimes the laundry 6 has an unbalanced portion C as shown in FIG. Predetermined time at a rotational speed N ₁ (20sec~30sec)
By driving, the laundry 6 stuck to the inner peripheral surface of the washing and dewatering drum 3 is more strongly pressed against the inner peripheral surface of the washing and dewatering drum 3 by the dehydrating action as it is on the outer peripheral side. Next, as shown in FIG.
Of the laundry 6 in the ideal condition where the centrifugal force at the position of the inner circumferential radius Ri of the laundry 6 in the ideal state is uniformly attached to the inner circumferential surface of the washing and dewatering drum 3, and the number of rotations is about Ri · ω ² = g. drop in N _2. If the laundry 6 stuck to the inner peripheral surface of the washing and dewatering drum 3 is uniform at the rotation speed N ₂ , this state can be maintained, but if there is an unbalanced portion,
As shown in FIG. 4 (b), the radius of gyration Ri balanced with gravity.
Although the laundry 6 described above is governed by centrifugal force and adheres to the inner peripheral surface of the washing and dewatering drum 3, the laundry 6 in the unbalanced portion has a smaller turning radius Ra and therefore has a larger gravity, and Only the laundry 6 in the balance portion falls under the influence of gravity near the upper part. Washing 6 unbalanced portions during rotation of the rotational speed N ₂ rises to the upper, by repeating the dropping, the laundry has unbalanced 6 will unravel, finally turning radius that balances the gravitational force The laundry 6 is at least Ri, and the laundry 6 adheres to the inner peripheral surface of the washing and dewatering drum 3, so that the laundry 6 is uniform. After rotating the washing / dewatering drum 3 for a predetermined time (20 s to 30 s) at the rotation speed N ₂ , the operation shifts to a predetermined dehydration rotation speed N ₀ . Number of rotations N ₁ , N
₂ is the centrifugal force CF ₁ > 1 at N ₁ against the gravity constant G
Centrifugal force at G and N ₂ CF ₂ ≦ 1G and N ₁ > 80r
pm, N ₂ <80 rpm. For example,
Washing and dewatering drum 3 is 480mmφ, and laundry 6 is 3k
g, the rotation speed N ₁ is about 100 rpm, and the rotation speed N
₂ becomes about 72 rpm.

As described above, according to the present control method, the unbalanced portion of the laundry 6 can be reduced before the dehydration process at the predetermined dehydration rotation speed N ₀ , and the vibration during the dehydration process is reduced. can do.

The rotation speeds N ₁ and N ₂ are determined based on the amount of laundry. The amount of the laundry 6 is detected, for example, by the load torque applied to the drive motor 5 at the time of starting. The size of the inner peripheral radius Ri of the laundry 6 in an ideal state in which the laundry 6 is uniformly stuck to the inner peripheral surface of the washing and dewatering drum 3 differs depending on the amount of the laundry 6, and the amount of the laundry 6 is reduced. When the amount is large, the inner radius Ri of the laundry 6 is small, and when the amount of the laundry 6 is small, the inner radius Ri of the laundry 6 is large. Therefore, the amount of the laundry 6 is detected before the dehydration process, and the number of rotations N ₁ , N
Change ₂ That is, when the amount of the laundry 6 is large, the rotation speeds N ₁ and N ₂ are set to be larger by the smaller the inner radius of the laundry 6 so as to balance the gravity at the inner radius position of the laundry 6.
When the amount of the laundry 6 is small, the rotation speeds N ₁ and N ₂ are reduced.

As described above, according to the present control method, the imbalance of the laundry 6 can be stably reduced by controlling the rotation speeds N ₁ and N ₂ according to the amount of the laundry 6. Can be.

The rotation speeds N ₁ and N ₂ are determined based on the quality of the laundry. The quality of the laundry 6 is detected, for example, by a change in load torque. Even when the weight of the laundry 6 is equal, the inner circumference radius Ri of the laundry 6 in the ideal state in which the laundry 6 is evenly stuck to the inner peripheral surface of the washing and dewatering drum 3 depending on the cloth quality of the laundry 6. The size of the laundry 6 is different, and the harder the cloth quality of the laundry 6 is, the smaller the inner radius Ri of the laundry 6 is, and conversely, the softer the cloth quality of the laundry 6 is, the larger the inner radius Ri of the laundry 6 is. Therefore, the cloth quality of the laundry 6 is detected before the dehydration process, and the rotation speeds N ₁ and N ₂ are changed based on the detection result. That is, when the cloth quality of the laundry 6 is hard, the rotation speeds N ₁ and N ₂ are increased by the small inner radius of the laundry 6 so that the inner radius of the laundry 6 is balanced with the gravity. When the fabric of _No. 6 is soft, the number of rotations N ₁ and N ₂ is reduced.

As described above, according to the present control method, the imbalance of the laundry 6 is stably reduced by controlling the rotation speeds N ₁ and N ₂ according to the quality of the laundry 6. be able to.

Detection of imbalance in the washing and dewatering drum 3 by the load torque of the drive motor 5 at the rotation speed N ₂ . A rotation speed of the drive motor 5 is detected by a rotation sensor, and a time variation rate of the detected rotation speed is calculated by the calculation unit 11 to detect a load torque of the drive motor 5. In the time chart of FIG. 3, the operation is performed at the rotation speeds N ₁ and N ₂ before reaching the predetermined dehydration rotation speed N ₀ . When the amount of unbalance of the laundry 6 as shown in FIG. 6A is large at the rotation speed N ₂ , the drive motor 5 is switched between when the unbalance portion is rotated upward and when it is rotated downward. The load torque is different. When rotating upward, the rotation of the washing and dewatering drum 3 is slow, and when rotating downward, the rotation of the washing and dewatering drum 3 is fast due to the inertia and gravity of the unbalanced portion, and the rotation is fast. As shown in FIG. 6 (b), not only the laundry 6 in the unbalanced portion but also the laundry 6 stuck uniformly other than the unbalanced portion of the laundry are different from the aforementioned control method. As shown in FIG. The load torque of the drive motor 5 is different between a state where the imbalance is large as shown in FIG. 6B and a state where the imbalance is small as shown in FIG. In contrast, the former is larger. Therefore, if the rotational speed of the variation rate is equal to or greater than the predetermined value of the rotational speed N ₂ at the detected drive motor 5 (unbalance detection), without entering the dehydrating operation, after the rotation at a rotational speed N ₁ again, the rotational speed N Rotate with ₂ to detect unbalance. The operation at the rotation speeds N ₁ and N ₂ is repeated until the imbalance disappears, and when the imbalance disappears, the process shifts to the dehydration process.

As described above, according to the present control method, the state of the laundry 6 varies greatly depending on the amount of unbalance of the laundry 6, so that a state where the amount of unbalance is large can be reliably detected.

An imbalance in the washing and dewatering drum 3 is detected based on the difference between the load torque of the drive motor 5 at the rotation speed N ₁ and the rotation torque at the rotation speed N ₂ . The respective time fluctuation rates at the rotation speed N ₁ and the rotation speed N ₂ are calculated by the calculation unit 11, and the calculation results are stored in the storage unit 12 to obtain a difference between the two. Detecting a change rate [delta] ₁ rpm of the rotational speed N ₁ at the drive motor 5 to detect the change rate [delta] ₂ rotational speed of the drive motor 5 for the next time the rotation speed N _2. As mentioned above control method, the rotational speed N [delta] ₂ if unbalanced state at ₂ [delta]
_Greater than ₁ . For this reason, the difference between the two is calculated by the arithmetic unit 11.
The difference is equal to or greater than a predetermined value (imbalance detection)
If not enter the dehydrating operation, rotates again after the rotation at a rotational speed N _1, at a rotational speed N _2, performs unbalance detection. The operation at the rotation speeds N ₁ and N ₂ is repeated until the imbalance disappears, and when the imbalance disappears, the process shifts to the dehydration process.

As described above, according to the present control method, it is possible to reliably detect a state in which the amount of unbalance of the laundry 6 is large even if there is no information on the amount of the laundry 6 and the cloth quality.

The detection of the fluctuation rate of the rotation speed of the drive motor 5 is detected by the fluctuation rate of the load torque of the drive motor 5. The rotation speed of the drive motor 5 is detected by the rotation sensor, and the input voltage of the drive motor 5 is varied by the control circuit 10 so as to keep this rotation speed constant. Then, from the change in the input voltage of the drive motor 5, the calculation unit 11 calculates the time variation rate of the load torque of the drive motor 5 to detect the variation rate of the rotation speed of the drive motor 5. Therefore, even if this method is used, it is possible to detect the imbalance in the washing and dewatering drum 3 in the above-described control method or the above-mentioned control method.

[0028] until equal to or less than a predetermined imbalance, repeated the rotational speed _{N 1 → N 2 → N 1} → N 2, after the repeated increase the rotational speed N _1, N ₂ is also the time of unbalance, given dehydration rotation speed Lower N ₀ . A description will be given with reference to the flowchart of FIG. After rotating the time chart of FIG. 3, at a rotational speed N ₁ during rotation of the rotational speed N ₂ of (step 101) the unbalance detected (step 102) (control method or) performed (step 103), the laundry 6 when the sensed unbalanced amount is large, again raised to the rotational speed N _1, after a predetermined time, is rotated at a rotational speed N _2, performs unbalance detection (step 101 to 103). Even if the rotation speeds N ₁ and N ₂ are repeated a predetermined number of times (step 1
04), when it is detected that the unbalance amount of the laundry 6 is large, water is supplied once to loosen the entanglement of the laundry 6, and the number of times of forward rotation / stop / reversal / stop of the washing / dehydrating drum 3 is set to 50 rpm. And after draining (Steps 105 to 10)
9) The rotation of the number of revolutions N ₁ and N ₂ is performed again. Thereafter, similarly, when the imbalance is large even after repeating the predetermined number of rotations, the rotation speed N ₁ and the rotation speed N ₂ ,
By increasing the rotation speeds of the rotation speeds N ₁ and N ₂ , the inner rotation radius of the laundry 6 that balances with gravity is reduced, the unbalanced allowable range is widened, and the predetermined dehydration rotation speed N ₀ is reduced (step 110), a rotation process of the rotation speeds N ₁ and N ₂ (steps 111 and 112) and a predetermined dehydration rotation speed N ₀ process (step 113) are performed to complete the dehydration. Step 10
When the imbalance detection of No. 3 detects that the amount of imbalance is small, the process immediately shifts to the predetermined dehydration rotation speed N ₀ stroke (Step 114) without changing each rotation speed, and completes dehydration.

As described above, according to the present control method, the amount of unbalance of the laundry 6 is detected, and when the amount of unbalance is large, the process shifts to the step of reducing the amount of unbalance again, and the amount of unbalance cannot be reduced. In some cases, the predetermined dehydration rotation speed N ₀ can be reduced, and the dehydration can be completed without generating large vibration.

[0030]

As described above, according to the first aspect of the present invention, during the dehydration operation of the laundry in the washing and dewatering drum, the predetermined dehydration rotation speed is reached before reaching the predetermined dehydration rotation speed. A plurality of stages of rotating at a lower rotation speed than each, and at least one of the plurality of stages has a control means for controlling so as to have a stage where the rotation speed is lower than the rotation speed of the previous stage, Before the dehydration process at a predetermined dehydration rotation speed, the laundry is uniformly attached to the inner peripheral surface of the washing and dehydrating drum so that the unbalanced portion can be reduced,
Vibration during the dehydration process can be reduced.

According to the second aspect of the present invention, the rotational speed at the preceding stage is N ₁ , and the rotational speed at the stage at which the rotational speed is decreased is N _1
2. The centrifugal force at the average inner radius of the laundry stuck to the inner peripheral surface of the washing and dewatering drum at the rotation speed N _{1 is} represented by C
F ₁ , when the centrifugal force at the average inner radius of the laundry stuck on the inner peripheral surface of the washing and dewatering drum at the rotation speed N ₂ is CF ₂ , and the gravitational constant is G, CF ₁ > 1 G; C
Since F ₂ ≦ 1 G, the laundry is uniformly stuck to the inner peripheral surface of the washing and dewatering drum, and the unbalanced portion is reduced, so that vibration during the dehydration process can be reliably reduced.

According to the third aspect of the present invention, the rotation speed N _{1 in the} preceding stage and the rotation speed N _{2 in the} stage in which the rotation speed decreases.
Is determined based on the amount of the laundry, so that even if the amount of the laundry changes, the imbalance of the laundry can be stably reduced.

According to the fourth aspect of the present invention, the rotation speed N _{1 in the} preceding stage and the rotation speed N _{2 in the} stage in which the rotation speed decreases.
Is determined based on the cloth quality of the laundry, so that even if the cloth quality of the laundry changes, the imbalance of the laundry can be stably reduced.

According to the fifth aspect of the present invention, the load of the laundry in the washing and dewatering drum is increased by the load torque of the motor for driving the washing and dewatering drum at the rotation speed N ₂ at the stage when the rotation speed decreases. Since the unbalance is detected, the load torque of the drive motor differs between a state where the imbalance is large and a state where the imbalance is small.
A state where the amount of unbalance of the laundry is large can be reliably detected.

According to the sixth aspect of the present invention, the rotational speed N _{1 in the} preceding stage and the rotational speed N _{2 in the} stage in which the rotational speed decreases are described.
Since the imbalance of the laundry in the washing and dewatering drum is detected by the difference in the load torque of the motor that drives the washing and dewatering drum at each time,
Since towards the load torque of the rotational speed N ₂ o'clock drive motor falling laundry if unbalanced condition occurs is increased, the state unbalance amount is large laundry can be detected more reliably.

According to the invention of claim 7, wherein, until below a predetermined imbalance, because you to repeat the steps of the rotational speed N ₁ and stage of the rotational speed N _2, the laundry during spin-drying operation The uniformity is improved, and the vibration can be further reduced.

According to the eighth aspect of the present invention, when the imbalance does not fall below the predetermined imbalance, the rotation speed N ₁ and the rotation speed N ₂ are respectively increased by predetermined amounts, and the predetermined dehydration rotation speed N ₀ is increased. Since the predetermined amount is lowered, the state where the imbalance does not become less than the predetermined unbalance can be better solved, and the dehydration can be completed without generating large vibration.

[Brief description of the drawings]

FIG. 1 is a diagram showing an internal configuration of an embodiment of a drum type washing machine according to the present invention.

FIG. 2 is a block diagram illustrating a configuration of a control system according to the embodiment.

FIG. 3 is a time chart at the time of a dehydration process of the embodiment.

4 is a diagram for explaining the state of laundry in the washing and dewatering drum o'clock rotational speed N ₂ and at the rotational speed N ₁ in the above embodiment.

FIG. 5 is a view showing an ideal state in which laundry is uniformly attached to an inner peripheral surface of a washing and dewatering drum in the embodiment.

FIG. 6 is a view for explaining a state of the laundry in the washing and dewatering drum at the rotation speed N ₁ and the rotation speed N ₂ when the imbalance of the laundry is large in the embodiment.

FIG. 7 is a flowchart for explaining an example of operation control during a dehydration process in the embodiment.

FIG. 8 is a diagram showing an internal configuration of a conventional drum type washing machine.

FIG. 9 is a diagram showing a state of laundry when the washing and dewatering drum is stopped in the above-described conventional technology.

FIG. 10 is a time chart at the time of a dehydration process of the above-described conventional technique.

FIG. 11 is a view for explaining a state of laundry in a washing and dewatering drum at the time of a dewatering process according to the conventional technique.

[Explanation of symbols]

 Reference Signs List 3 washing and dewatering drum 5 drive motor 6 laundry 10 control circuit (control means) C unbalanced portion of laundry Ri inner radius of laundry

Claims (8)

[Claims] 1. A dehydrating operation of laundry in a washing and dehydrating drum, comprising a plurality of stages of rotating at a lower rotational speed than the predetermined dehydrating rotational speed before reaching a predetermined dehydrating rotational speed, A drum-type washing machine comprising control means for controlling so that at least one of the plurality of stages has a stage in which the number of revolutions is lower than the number of revolutions in the preceding stage. Wherein N ₁ the rotational speed of the previous step, the rotational speed of stage the rotation speed is lowered N _2, laundry stuck to the inner peripheral surface of the washing and dewatering drum of the temporary rotational speed N ₁ Is the centrifugal force at the average inner radius of CF ₁ , the centrifugal force at the average inner radius of the laundry stuck on the inner peripheral surface of the washing and dewatering drum at the rotation speed N ₂ is CF ₂ , and the gravity constant is G. _2. The drum type washing machine according to claim ₁ , wherein CF ₁ > 1 G and CF ₂ ≦ 1 G are satisfied. 3. The drum type washing machine according to claim 1, wherein the rotation speed N _{1 in the} preceding stage and the rotation speed N _{2 in the} stage in which the rotation speed decreases are determined according to the amount of the laundry. . 4. The drum-type washing machine according to claim 1, wherein the number of revolutions N _{1 in the} preceding stage and the number of revolutions N _{2 in the} stage of decreasing the number of revolutions are determined according to the quality of the laundry. Machine. By 5. A load torque of the motor for driving the washing and dewatering drum in at the rotational speed N ₂ of the rotation speed is lowered step, characterized by detecting the unbalance of the laundry in the washing and dehydrating the drum The drum type washing machine according to claim 1 or 2, wherein 6. The washing and dewatering is performed by a difference between a load torque of a motor for driving the washing and dewatering drum at a rotation speed N ₁ at the preceding stage and at a rotation speed N ₂ at a stage of decreasing the rotation speed. The drum type washing machine according to claim 1 or 2, wherein the imbalance of the laundry in the drum is detected. 7. The drum-type washing machine according to claim 5, wherein the steps of the number of revolutions N ₁ and the number of steps of the number of revolutions N ₂ are repeated until the imbalance becomes equal to or less than a predetermined imbalance. 8. If the unbalance is not less than the predetermined unbalance, the rotation speed N ₁ and the rotation speed N ₂ are respectively increased by a predetermined amount, and the predetermined spin speed N ₀ is reduced by a predetermined amount. The drum type washing machine according to claim 7.