JP2024074341A - Drum type washing machine - Google Patents

Abstract

To provide a drum-type washing machine capable of increasing the accuracy of detecting imbalance when the weight of a single piece of clothing is reduced, suppressing an increase in operating time due to a reduction in retries, preventing termination of spin-drying before completion, and suppressing an increase in vibration when an imbalance is determined.
[Solution] A drum-type washing machine comprising a housing, an outer tub, a drum, a motor, a water supply valve, a vibration sensor, and a control device that controls the motor to retry spin-drying when an imbalance of clothes in the drum is detected by rotational pulsation judgment or vibration judgment during the spin-drying process, wherein the rotational pulsation judgment is a judgment that detects imbalance when the rotational pulsation of the drum exceeds a first threshold, and the vibration judgment is a judgment that detects imbalance when the vibration of the outer tub when the drum rotational speed is the resonant rotational speed of the outer tub exceeds a second threshold, and the first threshold is changed to a smaller threshold the higher the drum rotational speed when the vibration of the outer tub exceeds the second threshold.
[Selected figure] Figure 4

Description

The present invention relates to a drum-type washing machine that spins the drum at high speed to dehydrate wet clothes after washing.

Patent Document 1 is a document related to the spin-drying process of drum-type washing machines. In this document, the pulsation of the drum's rotation speed (hereinafter, sometimes referred to as "rotation fluctuation" following Patent Document 1) and the vibration of the outer tub are proportional to the degree of uneven distribution of clothes and other items inside the drum (hereinafter, referred to as "imbalance"), and spin-drying is performed while gradually correcting the imbalance using the following procedure (paragraphs 0032-0039, Figure 3, etc. of the document).

First, the drum rotation speed is increased to a first rotation speed (ω ₁ ) at which the wet clothes stick to the inner peripheral surface of the drum due to centrifugal force (205 in FIG. 3 of the same document). Then, when the drum rotation speed reaches the first rotation speed (ω ₁ ), the rotation speed is maintained for a predetermined time (206 in FIG. 3 of the same document), and a first imbalance determination is performed based on the magnitude of the rotation fluctuation (207 in FIG. 3 of the same document). If the rotation fluctuation at this time is greater than the first threshold, it is considered that the imbalance is large because the clothes are not evenly spread inside the drum or the clothes are overlapped. Therefore, the drum rotation is temporarily stopped, and the clothes stuck to the drum are dropped (215 in FIG. 3 of the same document), and the dropped clothes are loosened to eliminate the unevenness and tangles of the clothes, thereby correcting the imbalance (201 in FIG. 3 of the same document).

Furthermore, if the rotational fluctuation in the first imbalance determination (207 in FIG. 3 of the same document) is smaller than the first threshold, a second imbalance determination based on the magnitude of the rotational fluctuation is performed (208 in FIG. 3 of the same document). If the rotational fluctuation at this time is larger than the second threshold (a threshold smaller than the first threshold), it is considered that the imbalance is caused by overlapping parts of the clothes. Therefore, the drum rotation speed is reduced to a rotation speed (ω _n ) that is higher than the rotation speed during reverse rotation (ω ₀ ) and lower than the first rotation speed (ω ₁ ) (i.e., using a method different from that used when detecting an imbalance in the first imbalance determination), and the overlapping parts of the clothes are moved to correct the imbalance (213 in FIG. 3 of the same document).

Furthermore, if the rotational fluctuation in the second imbalance judgment is smaller than the second threshold, the drum rotation speed is further increased (209 in FIG. 3 of the same document), and a third imbalance judgment based on the magnitude of the outer tub vibration is then performed (210 in FIG. 3 of the same document). If the outer tub vibration at this time is greater than the third threshold, the drum rotation is temporarily stopped, and the clothes stuck to the drum are dropped (215 in FIG. 3 of the same document), just as when an imbalance is detected in the first imbalance judgment, and the dropped clothes are loosened to eliminate any unevenness or tangles in the clothes, thereby correcting the imbalance (201 in FIG. 3 of the same document).

As described above, in Patent Document 1, imbalances that occur during the spin-drying process are evaluated based on the rotational fluctuations of the drum at low rotation speeds (first and second imbalance judgments that detect relatively large imbalances) or based on the vibrations of the outer tub at high rotation speeds (third imbalance judgment that detects relatively small imbalances), and if an imbalance is found, the spin-drying process is repeated (hereinafter referred to as a "retry") while correcting the imbalance by, for example, stopping the rotation of the drum.

Patent No. 2018-149219

Now consider the spin-drying process that is performed after washing a single piece of clothing. In the following, a single piece of clothing that is washed will be referred to as a "single piece of clothing." If the single piece of clothing is a relatively small, highly absorbent piece of clothing, such as jeans or a bath mat, even if the drum is rotated at the spin-drying speed during spin-drying, the single piece of clothing is not large enough to stick evenly to the inner surface of the drum, and the imbalance is likely to be greater than when multiple pieces of clothing are spin-dryed at the same time (hereinafter referred to as "normal spin-drying"). For this reason, in the past, retries were likely to occur early in the spin-drying process for a single piece of clothing, and repeated retries accelerated the spin-drying process, which could result in significant changes in the imbalance state even in the early stages of the spin-drying process.

As described above, in Patent Document 1, threshold values are provided for each of the first to third imbalance determinations, but these threshold values are not intended for a single piece of clothing, where the weight of the clothing may be significantly reduced by a retry at the beginning of the spin cycle, causing the imbalance state to change. Therefore, in the drum-type washing machine in Patent Document 1, the following problems are conceivable when spin-drying a single piece of clothing.

First, in the low-speed rotation range, even if a retry reduces the weight of one piece of clothing and improves the imbalance, if that piece of clothing is unevenly attached to the inner surface of the drum, the fluctuation in drum rotation may exceed the first or second threshold, and the imbalance may be determined. In that case, even though the spinning state is such that a transition to a spinning in the high-speed rotation range is required, unnecessary retries may be repeated, or the spinning process may abnormally stop due to frequent retries in the low-speed rotation range.

In addition, in the high-speed rotation range, the third threshold value used to determine imbalance based on outer tub vibration is a constant value, so when imbalance is detected for a single piece of clothing that has been lightened by accelerated dehydration in a previous retry, the drum rotation speed will have increased considerably, resulting in considerable outer tub vibration and noise.

The present invention aims to provide a drum-type washing machine that appropriately performs unbalance judgment based on the rotational fluctuation of the drum at low rotation speeds and on the vibration of the outer tub at high rotation speeds, even when spinning one piece of clothing, and suppresses problems such as an increase in the number of retries, abnormal stops in the spin-drying process, and excessive vibration and noise of the outer tub.

In order to achieve the above object, the drum-type washing machine of the present invention is a drum-type washing machine that includes a housing, an outer tub installed in the housing, a drum that is rotatably installed in the outer tub and capable of storing clothes, a motor that rotates the drum, a water supply valve that supplies water to the drum, a vibration sensor that detects the vibration of the outer tub, and a control device that controls the motor to retry dehydration when an imbalance of clothes is detected in the drum during the dehydration process by a rotation pulsation judgment that determines the presence or absence of imbalance based on the rotation pulsation of the drum, or a vibration judgment that determines the presence or absence of imbalance based on the vibration of the outer tub, the rotation pulsation judgment is a judgment that detects an imbalance when the rotation pulsation of the drum exceeds a first threshold value, the vibration judgment is a judgment that detects an imbalance when the vibration of the outer tub exceeds a second threshold value when the rotation speed of the drum is the resonant rotation speed of the outer tub, and the first threshold value is changed to a smaller threshold value as the rotation speed of the drum when the vibration of the outer tub exceeds the second threshold value is higher.

The drum-type washing machine of the present invention can appropriately determine imbalance based on the rotational fluctuation of the drum at low rotation speeds and on the vibration of the outer tub at high rotation speeds, even when spinning one piece of clothing, and can suppress problems such as an increase in the number of retries, abnormal stops in the spin-drying process, and excessive vibration and noise of the outer tub.

Problems, configurations, and advantages other than those described above will become clear from the description of the embodiments below.

1 is a perspective view of a drum type washing machine according to a first embodiment. 2 is a cross-sectional view of the internal structure of the drum type washing machine of FIG. 1 as viewed from the right side. FIG. 13 is a diagram showing the drum rotation operation in the dehydration process when unbalance is not detected. FIG. 13 is a diagram showing the drum rotation operation in the dehydration process when an imbalance is detected. FIG. 4 is a flowchart of an imbalance determination process according to the first embodiment. FIG. 11 is a flowchart of an imbalance determination process according to the second embodiment. 13A to 13C are diagrams illustrating a drum rotating operation according to the second embodiment. 13A to 13C are diagrams illustrating a drum rotating operation according to the second embodiment. 13A to 13C are diagrams illustrating a drum rotating operation according to the second embodiment. FIG. 11 is a flowchart of an imbalance determination process according to the third embodiment.

The following describes an embodiment of a drum-type washing machine according to the present invention with reference to the drawings. Note that the drum-type washing machine according to the present invention also includes a drum-type washer-dryer equipped with a drying function.

First, a drum-type washing machine 100 according to a first embodiment of the present invention will be described with reference to Figures 1 to 4.

Figure 1 is a perspective view of a drum-type washing machine 100 of this embodiment, and Figure 2 is a cross-sectional view of the internal structure of the drum-type washing machine 100 of this embodiment, seen from the right side. As shown in both figures, the outer shell of the drum-type washing machine 100 is covered by a housing 1, which is composed of left and right side panels 1a, a front cover 1b, a rear cover 1c, a top cover 1d, and a bottom cover 11. The top cover 1d is provided with a water supply hose connection port 30 for supplying water from a water faucet to the drum-type washing machine 100.

The door 2 is for closing an opening (not shown) for putting in and taking out clothes, which is located approximately in the center of the front cover 1b, and is supported so as to be openable and closable by a hinge (not shown) provided on the front cover 1b. The door 2 opens when the door opening handle 2a is pulled to release a locking mechanism (not shown), and closes when the door 2 is pressed against the front cover 1b, locking the locking mechanism. The front cover 1b has a circular opening 1ba for putting in and taking out clothes, which is approximately concentric with the opening 9a of the front stay 9 and the opening 17a of the outer tub 17.

The operation/display panel 3 provided on the top of the housing 1 includes a power switch 4 and an operation switch 5. The operation/display panel 3 is electrically connected to a control device 13 provided inside the housing 1.

An outer tub 17 for storing water is provided inside the housing 1. The lower part of the outer tub 17 is supported in an anti-vibration manner by a total of four suspensions: suspensions 26a fixed to the left and right sides of the front of the lower cover 11, and suspensions 26b fixed to the left and right sides of the rear of the lower cover 11. The upper part of the outer tub 17 is connected to the upper stay 7 by a suspension device 12, so that the outer tub 17 is supported in a suspended state on the housing 1. The suspension device 12 is composed of, for example, a coil spring.

The outer tub 17 contains a drum 21 for storing clothes. A motor 22 for rotating the drum 21 is disposed behind the outer tub 17. The motor 22 has a shaft 22a, which serves as a rotation axis, penetrating the outer tub 17 and connected to the drum 21. The motor 22 also has a Hall element for detecting the motor rotation speed, and outputs the motor rotation speed detected by the Hall element to the control device 13.

A vibration sensor 28 is fixed to the bottom of the outer tub 17 to detect vibrations of the outer tub 17. This vibration sensor 28 is a three-axis vibration sensor, and outputs the detected three-axis vibrations to the control device 13.

The control device 13 appropriately controls the opening and closing of the water supply valve 31, the opening and closing of the drain valve 34a, the rotation of the motor 22, the heat generation of the heater (not shown), etc., according to commands input by the user via the operation and display panel 3, the detection values of various sensors, the control program, etc., to carry out each process such as washing, rinsing, spin-drying, and drying. Of these processes, the spin-drying process according to the present invention will be described in detail later. Based on the motor rotation speed input from the motor 22, the control device 13 calculates the number of rotations of the drum 21 corresponding to that motor rotation speed, and the pulsation (rotation fluctuation) of the drum rotation speed. Based on the three-axis vibration value input from the vibration sensor 28, the control device 13 also calculates the outer tub vibration value in any direction.

When the motor 22 is driven, the drum 21 is driven to rotate in both forward (clockwise when viewed from the front of the drum-type washing machine 100) and reverse (counterclockwise when viewed from the front of the drum-type washing machine 100). The rotation axis Az of the drum 21 is horizontal from the front to the rear of the drum-type washing machine 100, or is inclined so that the back side is downwards. Figure 2 shows a state in which it is inclined so that the back side is downwards.

The drum 21 is provided with a number of dewatering holes 21b for draining the wash water in the drum 21 into the outer tub 17, and is provided with a number of baffles 23 (only one is shown in FIG. 2) on its inner circumferential surface. The baffles 23 are spaced apart around the circumference of the drum 21 and lift up the clothes placed in the drum 21 as the drum 21 rotates. The baffles 23 extend in the front-to-rear direction of the drum 21.

A cylindrical fluid balancer 21c is provided at the front end (front side) of the drum 21. The outer tub 17 is an approximately cylinder with an opening at the front and a closed rear, with a bottom. The opening of the outer tub 17 and the loading port of the housing 1 are connected by a bellows 19 that easily expands and contracts in the front-to-rear direction. The bellows 19 is made of a ring-shaped elastic material, and the drum 21 is sealed with water when the door 2 is closed. The loading port of the housing 1, the opening of the outer tub 17, and the opening of the drum 21 are connected, and clothes can be put in and taken out of the drum 21 by opening the door 2. The outer tub 17 can be divided into a side including the opening and a side to which the motor 22 is attached.

A water supply valve 31 is disposed below the water supply hose connection port 30. One end of a water supply pipe 32 for supplying water to the outer tub 17 is connected to the water supply valve 31. When the water supply valve 31 is opened, water flows from the water supply hose connection port 30 through the water supply pipe 32 to the detergent container 33, and water is supplied into the outer tub 17 from the front water supply hose 35 or the rear water supply hose 36.

A drain valve 34a is provided in the drain path of the drain hose 34 provided at the bottom of the outer tub 17. When the drain valve 34a is closed, the water supplied to the outer tub 17 accumulates in the outer tub 17, and when the drain valve 34a is opened, the washing water in the outer tub 17 is drained from the drain hose 34 to the outside of the drum-type washing machine 100.

<Basic Operation of Drum Type Washing Machine 100>
Next, a basic operation of the drum type washing machine 100 will be described. First, the user presses the power switch 4 to start the drum type washing machine 100. The user then pulls the door opening handle 2a to open the door 2 and places clothes in the drum 21. After closing the door 2, the user operates the operation switch 5 to set up the operation and start the operation.

When operation begins, the drum 21 rotates under the control of the control device 13, and the laundry volume before water is poured is calculated. The laundry volume is calculated based on the current value of the motor 22 when it is rotated. At this time, the greater the laundry volume, the greater the load on the motor 22 and the greater the current value, so the laundry volume can be determined from the current value. Then, the amount of detergent to be dispensed is displayed on the operation and display panel 3 based on the laundry volume. At this time, the greater the calculated laundry volume, the greater the amount of detergent to be dispensed. The user checks the display on the operation and display panel 3 and pours a specified amount of detergent into the detergent container 33. The control device 13 then starts the washing process.

During the washing process, the control device 13 opens the water supply valve 31 and supplies water supplied from the water supply hose connection port 30 into the outer tub 17 together with detergent via the water supply hose 32, detergent container 33, and front water supply hose 35 or rear water supply hose 36. At this time, the larger the calculated laundry volume, the greater the amount of water supplied during the washing process. After performing this operation for a predetermined time, a washing operation is performed for a predetermined time in which the drum 21 is rotated forward, stopped, reversed, and stopped repeatedly. At this time, the laundry is lifted up by the baffle 23 and dropped repeatedly, thereby enhancing the cleaning power of the clothes.

After the washing process, the control device 13 executes the spin-drying process. In the spin-drying process, the drum 21 is rotated at a low rotation speed at which the clothes do not stick to the drum 21. At the low rotation speed, the clothes that have absorbed water in the washing process are lifted by the baffle 23 as the drum 21 rotates, and are spread on the inner surface of the drum 21 as the clothes fall. When the clothes start to spread, the rotation speed of the drum 21 is gradually increased to make the clothes stick to the drum 21. When the clothes stick to the drum 21, the rotation speed of the drum 21 is increased and the clothes are allowed to pass through the resonant rotation speed range of the outer tub 17, and are allowed to reach a steady rotation speed, thereby centrifugal dehydrating the water contained in the clothes. The resonant rotation speed of the outer tub 17 is the natural frequency (Hz) at which the outer tub 17 resonates, converted into rotation speed (rpm), and the outer tub 17 in this embodiment has three resonant rotation speeds r1, r2, and r3.

After the spin cycle, the control device 13 executes the rinsing cycle. In the rinsing cycle, the water supply valve 31 is opened, and water supplied from the water supply hose connection port 30 is supplied into the outer tub 17 via the water supply hose 32, detergent container 33, and front water supply hose 35 or rear water supply hose 36. As with the washing cycle, the greater the calculated laundry volume, the greater the amount of water supplied. In the rinsing cycle, as with the washing cycle, the drum 21 is repeatedly rotated forward, stopped, reversed, and stopped. At this time, an agitation operation is performed for a predetermined period of time, in which the clothes lifted by the baffle 23 fall.

The control device 13 then repeats the spin-drying and rinsing processes a predetermined number of times and moves on to the final spin-drying process.

If the drum-type washing machine has a drying function, the control device 13 executes the drying process after the final spin-drying process. The rotation speed of the drum 21 during the drying process is set to an even slower speed than during the washing process. During the drying process, the drum 21 rotates at a slow speed while a blower unit (not shown) blows warm air onto the clothes in the drum 21, drying the clothes while reducing wrinkles.

<How to determine imbalance>
Before describing the details of the spin-drying process of this embodiment, the method of determining the imbalance of this embodiment will be described. As described above, the spin-drying process is a process in which the rotation speed of the drum 21, which is stopped after the washing process or the rinsing process, is gradually increased to a steady rotation speed, and the high steady rotation speed is maintained for a predetermined time, thereby spinning out wet clothes, etc. In the region where the rotation speed of the drum 21 and the resonant rotation speed of the outer tub 17 match, the vibration of the outer tub 17 is amplified. Therefore, if there is an imbalance in the arrangement of clothes, etc. in the drum 21 during the spin-drying process, not only will excessive outer tub vibration and noise be generated, but the outer tub 17 may also collide with the housing 1.

Therefore, when the control device 13 detects an imbalance in the early stages of the spin-drying process before the drum rotation speed exceeds the outer tub resonance rotation speed range (the shaded area in Figure 3A), it temporarily stops the rotation of the drum 21, performs a loosening operation at low speed, and then controls the rotation of the motor 22 to increase the rotation speed of the drum 21 again and retry spin-drying.

Therefore, the control device 13 of this embodiment uses a method of determining the presence or absence of imbalance based on the rotational pulsation of the drum 21 (hereinafter simply referred to as "rotational pulsation determination") in combination with a method of determining the presence or absence of imbalance based on the detection value of the vibration sensor 28 (hereinafter simply referred to as "vibration determination") to determine the presence or absence of imbalance at an early stage of the spin-drying process, and when an imbalance is detected, the imbalance is corrected by a retry before the drum rotation speed is increased to the steady-state rotation speed.

The rotational pulsation judgment is a judgment method used when the rotational speed of the drum 21 is relatively low (for example, 100 rpm or less), and judges whether there is a relatively large imbalance caused mainly by the unevenness or overlap of clothes stuck to the inner surface of the drum 21. In this rotational pulsation judgment, it is judged that an imbalance has occurred when the rotational pulsation of the drum 21 calculated based on the output of the Hall element of the motor 22 is equal to or greater than a predetermined threshold value Ta.

Here, the rotational pulsation is the difference between the maximum and minimum rotational speeds when the drum 21 rotates once. The threshold value Ta is a value selected from a plurality of values (e.g., Ta1, Ta2, Ta3 (where Ta1>Ta2>Ta3)) pre-registered in the control device 13. The initial value Ta1 of the threshold value Ta is the largest threshold value, and is replaced by smaller threshold values Ta2 or Ta3 depending on the situation.

Vibration judgment is an imbalance judgment method used in the high-speed rotation range where the rotation speed of the drum 21 is relatively high, and judges whether or not there is a relatively small imbalance. In this vibration judgment, it is judged that an imbalance has occurred when the outer tub vibration value detected by the vibration sensor 28 is equal to or greater than a predetermined threshold value Tb. The threshold value Tb used here is a value determined according to the specifications of the outer tub 17, and the control device 13 has multiple threshold values Tb (e.g., Tb1, Tb2, Tb3) pre-registered that are switched according to the rotation speed of the drum 21.

The reason for switching the threshold value Tb according to the rotation speed of the drum 21 is as follows. That is, the outer tub 17 has a characteristic that the direction in which it is most likely to shake differs for each resonant rotation speed. Therefore, when performing vibration judgment in this embodiment, the control device 13 calculates the amount of outer tub vibration in the direction in which it is most likely to shake at the current rotation speed of the drum 21 based on the three-axis vibration value input from the vibration sensor 28, and compares this with the threshold value Tb for that vibration direction, thereby efficiently judging the occurrence of imbalance.

<Dehydration process>
Next, the specific rotational operation of drum 21 in the dewatering step will be described with reference to FIGS. 3A and 3B.

When there is no imbalance, in the spin-drying process of this embodiment, as shown in FIG. 3A, the rotation speed of the drum 21 is increased in stages until it passes through a resonant rotation speed range (e.g., 100 to 400 rpm) where the vibration displacement of the outer tub 17 increases, and then the drum is operated at a steady rotation speed (e.g., 900 rpm) for a predetermined time (e.g., 80 seconds) until spin-drying is complete.

In this example, the rotational pulsation detected in the rotational pulsation judgment section below 100 rpm was smaller than the predetermined threshold value Ta, so the imbalance was not detected by the rotational pulsation judgment, and the drum rotation speed was moved to the vibration judgment section without retrying. Also, in the resonant rotation speed range included in the vibration judgment section, the detection value of the vibration sensor 28 at each resonant rotation speed was smaller than the predetermined threshold value Tb, so the imbalance was not detected by the vibration judgment, and the drum rotation speed was increased to the normal rotation speed without retrying, and the spin-drying process was then terminated.

On the other hand, if there is an imbalance, in order to prevent the outer tub 17 from colliding with the housing 1 and to prevent an increase in vibration and noise at the steady rotation speed, in the dehydration process of this embodiment, as illustrated in FIG. 3B, two retries are performed to improve the imbalance, and then the drum rotation speed is increased to the steady rotation speed. Specifically, since the rotation pulsation detected in the rotation pulsation judgment section of 100 rpm or less was greater than a predetermined threshold value Ta, the imbalance is detected by the rotation pulsation judgment, and the first retry is performed to improve the imbalance. Also, in the resonant rotation speed range of the outer tub 17, the detection value of the vibration sensor 28 at a certain resonant rotation speed was greater than a predetermined threshold value Tb, so the imbalance is detected by the vibration judgment, and the second retry is performed to further improve the imbalance. After the second retry, the imbalance has been sufficiently improved, so the dehydration process can be terminated by the same procedure as in the example of FIG. 3A.

Here, we consider the significance of the threshold value Ta for determining rotational pulsation and the threshold value Tb for determining vibration.

Immediately after the start of dehydration, clothes contain a lot of water and are heavy, so the weight of the clothes is likely to be unevenly distributed (unbalanced) inside the drum 21. If a strict imbalance determination were made in this state, it could be easily determined that there is an imbalance and lead to repeated retries. Therefore, the initial value (Ta1) of the threshold value Ta for determining rotation pulsation is set to a large value, so that dehydration can continue with a relatively slow drum rotation speed unless there is a severe imbalance.

On the other hand, even if the imbalance is small enough to pass the rotational pulsation judgment section, if the imbalance is not suitable for high-speed rotation at the resonant rotation speed and is overlooked, there is a risk that the outer tank 17 and the housing 1 may collide, or that vibration and noise may increase, so it is necessary to detect even minor imbalances without fail and perform appropriate retries. For this reason, the threshold value Tb for the vibration judgment section is set small so that imbalances that are not suitable for high-speed rotation at the resonant rotation speed can be properly detected.

When spin-drying a single piece of clothing, which is highly absorbent and relatively small and therefore prone to large imbalances, there is a characteristic that even if the clothing passes through the rotation pulsation judgment section using a larger threshold value Ta, it is likely that imbalance detection (and subsequent retries) will be repeated in the vibration judgment section using a smaller threshold value Tb. If retries are repeated, the weight of the clothing will be significantly reduced in the early stages of the spin-drying process compared to before spin-drying, so the significance of setting a larger threshold value Ta for spin-drying pulsation judgment will gradually decrease, and instead the disadvantages of not making strict imbalance judgments in the rotation pulsation judgment section (for example, prolonged spin-drying process or abnormal stoppage due to frequent retries in the vibration judgment section) will become greater.

Therefore, in this embodiment, the threshold value Ta for determining rotational pulsation is gradually lowered according to the progress of the spin cycle before a retry, so that when the spin cycle for one piece of clothing is retried, the presence or absence of imbalance can be more appropriately determined using the lowered threshold value Ta.

<<Flowchart>>
Next, the procedure of the spin-drying process of this embodiment will be described in detail with reference to the flow chart of FIG. 4, on the premise that one piece of laundry with a large imbalance is to be spin-dried.

First, in step S11, the control device 13 controls the rotation speed of the motor 22 to gradually increase the rotation speed of the drum 21.

Next, in step S12, the control device 13 performs an imbalance determination based on whether the rotational pulsation of the drum 21 in the rotational pulsation determination section is smaller than the threshold value Ta for determining rotational pulsation. If the requirement is met, the process proceeds to step S15, and if the requirement is not met, the process proceeds to step S13. Note that the initial value of the threshold value Ta is threshold value Ta1, which is the largest of the multiple threshold values Ta prepared.

In step S13, the control device 13 stops the rotation of the motor 22 and also stops the rotation of the drum 21. This causes the clothes stuck to the inner surface of the drum 21 to fall due to centrifugal force.

In step S14, the control device 13 controls the rotation of the motor 22 to perform a loosening operation and correct the imbalance. After that, the rotation speed of the drum 21 is increased again (step S11).

On the other hand, in step S15, the control device 13 controls the rotation speed of the motor 22 to gradually increase the rotation speed of the drum 21 toward the first resonant rotation speed r1 (e.g., 180 rpm) of the outer tank 17.

In step S16, the control device 13 performs an imbalance determination based on whether the vibration value of the outer tank 17 before reaching the first resonant rotation speed r1 is smaller than the threshold value Tb1 for vibration determination. If the requirement is met, the process proceeds to step S17, and if the requirement is not met, the process proceeds to step S13. Note that the vibration value used in this step is the vibration value in the direction in which the outer tank 17 is most likely to shake at the first resonant rotation speed r1, and the threshold value Tb1 is a threshold value prepared as the threshold value Tb for that direction.

In step S17, the control device 13 controls the rotation speed of the motor 22 to gradually increase the rotation speed of the drum 21 toward the second resonant rotation speed r2 (e.g., 240 rpm) of the outer tank 17.

In step S18, the control device 13 performs an imbalance determination based on whether the vibration value of the outer tank 17 before reaching the second resonant rotation speed r2 is smaller than the threshold value Tb2 for vibration determination. If the requirement is met, the process proceeds to step S1a, and if the requirement is not met, the process proceeds to step S19. Note that the vibration value used in this step is the vibration value in the direction in which the outer tank 17 is most likely to shake at the second resonant rotation speed r2, and the threshold value Tb2 is a threshold value prepared as the threshold value Tb for that direction.

In step S19, the control device 13 reduces the threshold value Ta for judging rotational pulsation from the initial value Ta1 to Ta2 (where Ta1>Ta2), and then proceeds to step S13. As a result, the threshold value Ta2, which is smaller than the threshold value Ta1, is used for subsequent rotational pulsation judgments.

In step S1a, the control device 13 controls the rotation speed of the motor 22 to gradually increase the rotation speed of the drum 21 toward the third resonant rotation speed r3 (e.g., 360 rpm) of the outer tank 17.

In step S1b, the control device 13 performs an imbalance determination based on whether the vibration value of the outer tank 17 before reaching the third resonant rotation speed r3 is smaller than the threshold value Tb3 for vibration determination. If the requirement is met, the control device 13 proceeds to step S1d, and if the requirement is not met, the control device 13 proceeds to step S1c. Note that the vibration value used in this step is the vibration value in the direction in which the outer tank 17 is most likely to shake at the third resonant rotation speed r3, and the threshold value Tb3 is a threshold value prepared as the threshold value Tb for that direction.

In step S1c, the control device 13 lowers the threshold value Ta for judging rotational pulsation from the previous one to Ta3 (where Ta1>Ta2>Ta3), and then proceeds to step S13. As a result, the threshold value Ta3, which is smaller than the threshold value Ta1 and the threshold value Ta2, is used for subsequent rotational pulsation judgments.

In step S1d, the control device 13 controls the rotation speed of the motor 22 to gradually increase the rotation speed of the drum 21 toward a steady rotation speed (e.g., 900 rpm). Then, after continuing dehydration at the steady rotation speed for a predetermined period of time, the dehydration operation is terminated.

As described above, in this embodiment, the threshold value Ta used in subsequent rotation pulsation judgments is gradually lowered depending on the timing at which an imbalance is detected in the resonant rotation speed range (i.e., taking into account the amount of water spin-dried in the spin-drying process before a retry). As a result, if the threshold value Ta were constant, an imbalance that could only be detected in vibration judgment sections where the drum rotation speed is high can now be detected in advance in rotation pulsation judgment sections where the drum rotation speed is low.

Therefore, according to this embodiment, the accuracy of unbalance detection in the low rotation speed range for a single piece of clothing whose weight has been reduced by retrying can be improved, and by performing spin-drying when the unbalance is small, an increase in retries in the resonance rotation speed range of the outer tub 17 can be suppressed, and operation can be prevented from terminating before spin-drying is completed.

Next, a drum-type washing machine 100 according to a second embodiment of the present invention will be described with reference to Figures 5, 6A, and 6B. Note that a duplicated description of the points common to the first embodiment will be omitted.

This embodiment differs from the first embodiment in that if an imbalance is detected by vibration judgment during the spin cycle before a retry, during a retry, a period is provided in which the drum 21 rotates for a certain period of time at a lower rotation speed than the resonant rotation speed before the drum rotation speed reaches the resonant rotation speed at which the imbalance has been detected.

The specific spin-drying operation of the drum-type washing machine 100 of this embodiment is shown in the flowchart of FIG. 5. Note that the processing specific to this embodiment is steps S25 to S26, S29 to S2a, and S2e to S2f in FIG. 5. The other processing corresponds to steps S11 to S1d in FIG. 4, so the significance of the processing specific to this embodiment will be explained in detail below.

Step S25 is a process that is performed when the requirements of step S22 (corresponding to step S12) are met. In this step, the control device 13 determines whether an imbalance was detected by the threshold value Tb1 for the first resonant rotation speed r1 during spin-drying before the retry. If the requirements are met, the process proceeds to step S26, and if the requirements are not met, the process proceeds to step S27 (corresponding to step S15).

In step S26, the control device 13 controls the rotation speed of the motor 22 to rotate the drum 21 for a certain period of time at a rotation speed (e.g., 160 rpm) lower than the resonance rotation speed r1 (e.g., 180 rpm) of the outer tub 17 (see FIG. 6A). During this period, water is expedited from the clothes and the imbalance is reduced, increasing the possibility that the imbalance will not be detected in the imbalance determination using the threshold value Tb1 in step S28 (corresponding to step S16).

Step S29 is a process that is performed when the requirements of step S28 (corresponding to step S16) are met. In this step, the control device 13 determines whether an imbalance was detected by the threshold value Tb2 for the second resonant rotation speed r2 during spin-drying before the retry. If the requirements are met, the process proceeds to step S2a, and if the requirements are not met, the process proceeds to step S2b (corresponding to step S17).

In step S2a, the control device 13 controls the rotation speed of the motor 22 to rotate the drum 21 for a certain period of time at a rotation speed (e.g., 220 rpm) lower than the resonance rotation speed r2 (e.g., 240 rpm) of the outer tub 17 (see FIG. 6B). During this period, water is expedited from the clothes and the imbalance is reduced, so that the imbalance determination using the threshold value Tb2 in step S2c (corresponding to step S18) is more likely to not detect the imbalance.

Furthermore, step S2e is a process that is performed when the requirements of step S2c (corresponding to step S18) are met. In this step, the control device 13 determines whether an imbalance was detected by the threshold value Tb3 for the third resonant rotation speed r3 during spin-drying before the retry. If the requirements are met, the process proceeds to step S2f, and if the requirements are not met, the process proceeds to step S2g (corresponding to step S1a).

In step S2f, the control device 13 controls the rotation speed of the motor 22 to rotate the drum 21 for a certain period of time at a rotation speed (e.g., 340 rpm) lower than the resonance rotation speed r3 (e.g., 360 rpm) of the outer tub 17 (see FIG. 6C). During this period, water is expedited from the clothes and the imbalance is reduced, increasing the possibility that the imbalance will not be detected in the imbalance determination using the threshold value Tb3 in step S2h (corresponding to step S1b).

As described above, according to this embodiment, the system checks whether an imbalance has been detected in the resonant speed range before a retry, and if an imbalance has been detected, the drum 21 is rotated for a certain period of time at a speed lower than the resonant speed at which the imbalance was detected, thereby facilitating the draining of water from the clothes and reducing the imbalance, thereby suppressing an increase in vibration and noise at the resonant speed during a retry.

Next, a drum-type washing machine 100 according to a third embodiment of the present invention will be described with reference to FIG. 7. Note that a duplicate description of the points common to the first embodiment will be omitted.

This embodiment differs from the first embodiment in that the process performed before the loosening operation in step S35 (corresponding to step S14) is switched depending on the timing of the detection of the imbalance, and the length of the spin-drying time at the steady rotation speed is switched depending on whether or not an imbalance has been detected by vibration judgment.

The specific spin-drying operation of the drum-type washing machine 100 of this embodiment is shown in the flowchart of FIG. 7. Note that the processing specific to this embodiment is steps S33 to S34 and S3g to S3i in FIG. 7, and the other processing corresponds to the processing of steps S11 to S1d in FIG. 4, so the significance of the processing specific to this embodiment will be explained in detail below.

Step S33 is a process that is performed when an imbalance is detected in step S32 (corresponding to step S12) or step S37 (corresponding to step S17). In this step, similar to step S13 in the first embodiment, the control device 13 stops the rotation of the motor 22 and also stops the rotation of the drum 21. However, when going through this step, unlike when going through step S3b, which is also a drum rotation stopping step, step S34 is performed before performing the loosening operation of step S35 (corresponding to step S14).

In step S34, the control device 13 opens the water supply valve 31 to pour water into the drum 21. If an imbalance is detected in step S32 or step S37 (i.e., if an imbalance is detected in an area where the rotation speed of the drum 21 is relatively low), the dehydration of the clothes has not progressed very far, so pouring water into the drum 21 at this point has little detrimental effect on subsequent dehydration. However, the increased moisture content of the clothes makes it easier to move the clothes and untangle them during the dehydration operation (step S35), which has the great advantage of making it easier to correct the imbalance.

When an imbalance is detected in step S39 (corresponding to step S18) or step S3d (corresponding to step S1b), step S34 (water injection into drum) is not performed because at the time of step S39 or step S3d, the laundry has already been substantially dehydrated, and injecting water into drum 21 at this point would actually increase the time required to complete the dehydration.

In step S3g, the control device 13 determines whether there is a history of detecting an imbalance through vibration determination (steps S37, S39, S3d). If the requirements are met, the process proceeds to step S3i, and if the requirements are not met, the process proceeds to step S3h.

In step S3i, the control device 13 changes the spin-drying time at the steady rotation speed to a shorter setting (e.g., 40 seconds) than the normal setting (e.g., 80 seconds), and ends the spin-drying operation when the new setting time has elapsed. This is because it is believed that the repeated spin-drying at the high rotation speed has led to more dehydration than would occur if there were no retries, and therefore shortening the spin-drying time at the steady rotation speed would have little adverse effect on the spin-drying, and also because if the spin-drying time at the steady rotation speed is not shortened, the time required to complete the spin-drying operation may be significantly longer than if there were no retries.

In particular, when a single piece of clothing is to be dehydrated, it tends to stick to the inner surface of the drum 21, so compared to normal washing, centrifugal force acts on the clothing, making it easier to dehydrate. Therefore, when dehydrating a single piece of clothing, sufficient dehydration can be achieved even if the operating time at the normal rotation speed is shortened, and it is possible to prevent an increase in the dehydration operating time.

On the other hand, in step S3h, the control device 13 keeps the spin-drying time at the steady rotation speed at the normal setting (e.g., 80 seconds) and ends the spin-drying operation when this setting time has elapsed.

As described above, according to this embodiment, the method of correcting the imbalance can be changed depending on the rotation speed of the drum 21 where the imbalance is detected, making it possible to correct the imbalance according to the condition of each piece of clothing, and suppressing the increase in operating time due to retries.

100... drum type washing machine,
17...Outer tank,
21...Drums,
22...Motor,
28...Vibration sensor,

Claims (4)

A housing and
An outer tank installed in the housing;
a drum that is rotatably installed in the outer tub and capable of storing clothes;
A motor for rotating the drum;
a water supply valve for supplying water to the drum;
a vibration sensor for detecting vibration of the outer tank;
a control device that controls the motor to retry dehydration when an imbalance of the clothes in the drum is detected during a dehydration process by a rotation pulsation determination that determines the presence or absence of imbalance based on the rotation pulsation of the drum or a vibration determination that determines the presence or absence of imbalance based on the vibration of the outer tub;
A drum type washing machine comprising:
The rotation pulsation determination is a determination for detecting an imbalance when the rotation pulsation of the drum exceeds a first threshold value,
The vibration determination is a determination for detecting an imbalance when a vibration of the outer tub exceeds a second threshold value when the rotation speed of the drum is a resonant rotation speed of the outer tub,
The drum-type washing machine, characterized in that the first threshold value is changed to a smaller threshold value as the rotation speed of the drum when the vibration of the outer tub exceeds the second threshold value is higher. In the drum type washing machine according to claim 1,
The control device, when detecting an imbalance through the vibration judgment, is characterized in that, when retrying dehydration, it rotates the drum for a predetermined time at a rotation speed lower than the drum rotation speed when the vibration of the outer tub exceeded the second threshold. In the drum type washing machine according to claim 1,
The control device is characterized in that if the rotation speed of the drum is low when the imbalance is detected, the control device supplies water to the drum and then retries spin-drying, and if the rotation speed of the drum is high when the imbalance is detected, the control device retries spin-drying without supplying water to the drum. In the drum type washing machine according to claim 1,
The drum-type washing machine is characterized in that, when an imbalance is detected by the vibration judgment, the control device shortens the time for which the drum is rotated at a steady rotation speed when retrying dehydration, compared to when an imbalance is not detected by the vibration judgment.

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