Drum-type washing machine

Abstract

To provide a drum type washing machine which enhances detection accuracy of unbalance when clothing weight of one piece of clothing reduces, which suppresses increase in operation time due to reduction in retry, which prevents dewatering from being finished incomplete, and which can suppress increase in vibration at the time of unbalance determination.SOLUTION: A drum type washing machine includes: a housing; an outer tub; a drum; a motor; a water supply valve; a vibration sensor; and a control device which controls the motor so as to retry dewatering when unbalance of clothing in the drum is detected by rotation pulsation determination or vibration determination in a dewatering step. The rotation pulsation determination is the determination which detects unbalance when rotation pulsation of the drum has surpassed a first threshold value. The vibration determination is the determination which detects unbalance when vibration of the outer tub when the rotational frequency of the drum is resonance rotational frequency of the outer tub has surpassed a second threshold value. The first threshold value is changed into a smaller threshold value as the rotational frequency of the drum is higher when the vibration of the outer tub has surpassed the second threshold value.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a drum-type washing machine that dehydrates wet clothes and the like after washing by rotating a drum at high speed.

Background Art

[0002] As a document related to the dehydration process of a drum-type washing machine, there is Patent Document 1. In this document, it is utilized that the pulsation of the drum rotation speed (hereinafter, may also be referred to as "rotation variation" following Patent Document 1) and the vibration of the outer tub are proportional to the magnitude of the imbalance (hereinafter, referred to as "unbalance") of clothes and the like in the drum, and dehydration is carried out while gradually correcting the unbalance in the following procedure (paragraphs 0032 to 0039 of the same document, FIG. 3, etc.).

[0003] First, the drum rotation speed is increased to a first rotation speed (ω1) such that the wet clothes stick to the inner peripheral surface of the drum by centrifugal force (205 in FIG. 3 of the same document). When the drum rotation speed reaches the first rotation speed (ω1), the rotation speed is maintained for a predetermined time (206 in FIG. 3 of the same document), and a first unbalance determination based on the magnitude of the rotation variation is carried out (207 in FIG. 3 of the same document). When the rotation variation at this time is greater than the first threshold value, it is considered that the unbalance is in a large state due to either the clothes not spreading evenly in the drum or the clothes overlapping each other. Therefore, the drum rotation is temporarily stopped, the clothes sticking to the drum are once dropped (215 in FIG. 3 of the same document), and the loosening operation of the dropped clothes is performed to eliminate the unevenness and entanglement of the clothes, thereby correcting the unbalance (201 in FIG. 3 of the same document).

[0004] Also, when the rotation variation in the first unbalance determination (207 in FIG. 3 of the same document) is smaller than the first threshold value, a second unbalance determination based on the magnitude of the rotation variation is carried out (208 in FIG. 3 of the same document). When the rotation variation at this time is greater than the second threshold value (a threshold value smaller than the first threshold value), it is considered that the unbalance is caused by a part of the clothes overlapping. Therefore, the drum rotation speed is set to a rotation speed higher than the rotation speed (ω0) during reverse rotation and lower than the first rotation speed (ω1) (ωn By reducing the pressure (i.e., using a different method than when detecting imbalance in the first imbalance judgment), the areas where the clothing overlaps are moved to correct the imbalance (Figure 3, 213 of the same document).

[0005] Furthermore, if the rotational fluctuation in the second unbalance determination is smaller than the second threshold, the drum rotation speed is further increased (Figure 3, 209 in the same document), and a third unbalance determination is performed based on the magnitude of the outer drum vibration (Figure 3, 210 in the same document). If the outer drum vibration at this time is greater than the third threshold, the drum rotation is temporarily stopped, similar to when an unbalance is detected in the first unbalance determination, to allow the clothes that were stuck to the drum to fall (Figure 3, 215 in the same document), and the unbalance is corrected by loosening the fallen clothes and eliminating any unevenness or tangling of the clothes (Figure 3, 201 in the same document).

[0006] As described above, Patent Document 1 evaluates the imbalance that occurs during the dewatering process based on a determination based on the rotational fluctuations of the drum in the low-speed rotation range (first and second imbalance determinations that detect relatively large imbalances), or based on a determination based on the vibration of the outer tub in the high-speed rotation range (third imbalance determination that detects relatively small imbalances). If an imbalance is found, the dewatering process is repeated (hereinafter referred to as "retry") while correcting the imbalance by stopping the rotation of the drum. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 2018-149219 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] Here, let's consider the spin-drying process performed after washing a single garment. In the following, a garment washed individually will be referred to as a "single garment." When a single garment is a relatively small garment with high water absorption, such as jeans or a bath mat, even if the drum is rotated at the spin-drying speed, the garment is not large enough to adhere uniformly to the inner surface of the drum. Therefore, the imbalance tends to be greater compared to when multiple garments are spin-dried simultaneously (hereinafter referred to as "normal spin-drying"). Consequently, retries were more likely to occur in the early stages of the spin-drying process for single garments, and repeated retries accelerated the spin-drying process, resulting in significant changes in the imbalance even in the early stages of the spin-drying process.

[0009] As described above, Patent Document 1 provides thresholds for each of the first to third unbalance judgments, but these thresholds are not designed for a single garment where the weight of the garment may be significantly reduced and the unbalance state may change due to retries in the initial stages of the spin-drying process. Therefore, the drum-type washing machine described in Patent Document 1 may have the following problems when spin-drying a single garment.

[0010] First, in the low-speed rotation range, even if the unbalance is corrected by retrying by making one garment lighter, if that garment is unevenly stuck to the inner surface of the drum, the drum's rotational fluctuation may exceed the first or second threshold, potentially resulting in an unbalance being detected. In that case, even though the dehydration state should transition to the high-speed rotation range, unnecessary retries may be repeated, or the dehydration process may abnormally stop due to frequent retries in the low-speed rotation range.

[0011] Furthermore, in the high-speed rotation range, the third threshold used for unbalance detection based on outer tub vibration is constant. Therefore, when an unbalance of a single garment that has been lightened through previous retries is detected, the drum rotation speed must be considerably high, resulting in a problem of considerable outer tub vibration and noise.

[0012] Therefore, the present invention aims to provide a drum-type washing machine that appropriately performs unbalance detection based on drum rotation fluctuations in the low-speed rotation range and unbalance detection based on outer tub vibration in the high-speed rotation range, even when spinning a single garment, thereby suppressing problems such as an increase in the number of retries, abnormal stoppage of the spinning process, and excessive vibration and noise of the outer tub. [Means for solving the problem]

[0013] To achieve the above objective, the drum-type washing machine of the present invention comprises a housing, an outer tub installed inside the housing, a drum rotatably installed inside 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 vibrations of the outer tub, and a control device that controls the motor to retry the spin-drying process when an imbalance in the clothes inside the drum is detected by a rotational pulsation determination that determines whether or not there is an imbalance based on the rotational pulsation of the drum, or by a vibration determination that determines whether or not there is an imbalance based on the vibration of the outer tub, wherein the rotational pulsation determination is a determination that detects an imbalance when the rotational pulsation of the drum exceeds a first threshold, and the vibration determination is a determination that detects an imbalance when the vibration of the outer tub exceeds a second threshold when the rotational speed of the drum is the resonant rotational speed of the outer tub, and the first threshold is changed to a smaller threshold as the rotational speed of the drum when the vibration of the outer tub exceeds the second threshold increases. [Effects of the Invention]

[0014] According to the drum-type washing machine of the present invention, even when spinning a single garment, it is possible to appropriately perform unbalance detection based on drum rotation fluctuations in the low-speed rotation range and unbalance detection based on outer tub vibration in the high-speed rotation range, thereby suppressing problems such as an increase in the number of retries, abnormal stoppage of the spin-drying process, and excessive vibration and noise of the outer tub.

[0015] Other issues, configurations, and effects not mentioned above will be clarified by the following description of the embodiments. [Brief explanation of the drawing]

[0016] [Figure 1] Perspective view of the drum washing machine according to Embodiment 1. [Figure 2] Cross-sectional view of the internal structure of the drum washing machine of FIG. 1 as viewed from the right side. [Figure 3A] Diagram showing the drum rotation operation in the dehydration process when unbalance is not detected. [Figure 3B] Diagram showing the drum rotation operation in the dehydration process when unbalance is detected. [Figure 4] Flowchart diagram of unbalance determination according to Embodiment 1. [Figure 5] Flowchart diagram of unbalance determination according to Embodiment 2. [Figure 6A] Diagram showing the drum rotation operation according to Embodiment 2. [Figure 6B] Diagram showing the drum rotation operation according to Embodiment 2. [Figure 6C] Diagram showing the drum rotation operation according to Embodiment 2. [Figure 7] Flowchart diagram of unbalance determination according to Embodiment 3.

Mode for Carrying Out the Invention

[0017] Hereinafter, embodiments of the drum washing machine according to the present invention will be described with reference to the drawings. Note that the drum washing machine of the present invention includes a drum washing and drying machine having a drying function.

Embodiment

[0018] First, the drum washing machine 100 according to Embodiment 1 of the present invention will be described with reference to FIGS. 1 to 4.

[0019] Figure 1 is a perspective view of the 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, viewed from the right side. As shown in both figures, the outer casing of the drum-type washing machine 100 is covered by a housing 1, which consists 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 tap to the drum-type washing machine 100.

[0020] Door 2 is for closing the opening (not shown) for loading and unloading 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. Door 2 opens when the door release handle 2a is pulled, disengaging the locking mechanism (not shown), and closes when it is pressed against the front cover 1b, locking the mechanism. The front cover 1b has a circular opening 1ba for loading and unloading clothes, which is approximately concentric with the opening 9a of the front stay 9 and the opening 17a of the outer tub 17.

[0021] The operation / display panel 3, located on the top of the enclosure 1, is equipped with a power switch 4 and an operation switch 5. The operation / display panel 3 is electrically connected to the control device 13 located inside the enclosure 1.

[0022] The housing 1 contains an outer tank 17 for holding water. The lower part of the outer tank 17 is vibration-damped and supported 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 tank 17 is connected to the upper stay 7 by a suspension device 12, so that the outer tank 17 is suspended from the housing 1. The suspension device 12 is composed of, for example, coil springs.

[0023] The outer tub 17 contains a drum 21 for storing clothes. A motor 22 for rotating the drum 21 is located at the rear of the outer tub 17. The motor 22 has a shaft 22a, which is the axis of rotation, that passes through the outer tub 17 and is connected to the drum 21. The motor 22 is also equipped with 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.

[0024] A vibration sensor 28 is fixed to the lower part of the outer tank 17 to detect vibrations of the outer tank 17. This vibration sensor 28 is a 3-axis vibration sensor and outputs the detected 3-axis vibrations to the control device 13.

[0025] 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 heating of the heater (not shown), etc., in accordance with commands input by the user via the operation / display panel 3, detected values ​​from various sensors, control programs, etc., and performs each process such as washing, rinsing, dewatering, and drying. Of these processes, the details of the dewatering process according to the present invention will be described later. The control device 13 calculates the rotation speed of the drum 21 corresponding to the motor rotation speed input from the motor 22, as well as the pulsation (rotational fluctuation) of the drum rotation speed. The control device 13 also calculates the vibration value of the outer tub in any direction based on the 3-axis vibration value input from the vibration sensor 28.

[0026] When the motor 22 is driven, the drum 21 rotates in both forward (clockwise when viewing the drum-type washing machine 100 from the front) and reverse (counterclockwise when viewing the drum-type washing machine 100 from the front). The rotation axis Az of the drum 21 is horizontal from the front to the rear of the drum-type washing machine 100, or inclined so that the rear side is downward. Figure 2 shows the state inclined so that the rear side is downward.

[0027] The drum 21 is provided with multiple drainage holes 21b for draining the wash water inside the drum 21 into the outer tub 17, and multiple baffles 23 (only one is shown in Figure 2) are provided on its inner circumferential surface. The multiple baffles 23 are spaced apart in the circumferential direction of the drum 21 and lift the clothes placed inside the drum 21 as the drum 21 rotates. The baffles 23 extend in the front-to-back direction of the drum 21.

[0028] A cylindrical fluid balancer 21c is provided at the front end (front side) of the drum 21. The outer tub 17 is a roughly cylindrical shape with a bottom, open at the front and closed at the rear. The opening of the outer tub 17 and the input port of the housing 1 are connected by a bellows 19 that expands and contracts in the front-to-back direction. The bellows 19 is made of an annular elastic member and seals the drum 21 with water when the door 2 is closed. The input port of the housing 1, the opening of the outer tub 17, and the opening of the drum 21 are in communication with each other, and clothes can be loaded and unloaded into the drum 21 by opening the door 2. The outer tub 17 can be divided into the side including the opening and the side to which the motor 22 is attached.

[0029] A water supply valve 31 is located below the water supply hose connection port 30. One end of a water supply pipe 32 for supplying water to the outer tank 17 is connected to the water supply valve 31. By opening the valve of the water supply valve 31, water flows from the water supply hose connection port 30 through the water supply pipe 32 to the detergent container 33, and is supplied into the outer tank 17 through the front water supply hose 35 or the rear water supply hose 36.

[0030] A drain valve 34a is provided in the drainage path of the drain hose 34 located at the bottom of the outer tub 17. When the drain valve 34a is closed, the water supplied to the outer tub 17 accumulates inside the outer tub 17, and when the drain valve 34a is opened, the wash water in the outer tub 17 is drained out of the drum-type washing machine 100 through the drain hose 34.

[0031] <Basic Operation of 100 Drum-Type Washing Machines> Next, the basic operation of the drum-type washing machine 100 will be explained. In the drum-type washing machine 100, the user first presses the power switch 4 to start the machine. Then, the user pulls the door opening handle 2a to open the door 2 and puts clothes into the drum 21. After closing the door 2, the user operates the operation switch 5 to set the operation and start the machine.

[0032] When operation begins, the control device 13 controls the rotation of the drum 21 to calculate the amount of laundry before water is added. The amount of laundry is calculated based on the current value of the motor 22 when it is rotated. At this time, the larger the amount of laundry, the greater the load on the motor 22 and the larger the current value, so the amount of laundry can be determined by the current value. Then, the amount of detergent to be added is displayed on the operation / display panel 3 based on the amount of laundry. At this time, the larger the calculated amount of laundry, the more detergent to add. The user checks the display on the operation / display panel 3 and adds the predetermined amount of detergent to the detergent container 33. After that, the control device 13 starts the washing process.

[0033] 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 to the outer tub 17 along with detergent via the water supply hose 32, detergent container 33, and either the front water supply hose 35 or the rear water supply hose 36. At this time, the larger the calculated laundry capacity, the greater the amount of water supplied during the washing process. After performing this operation for a predetermined time, the drum 21 is rotated forward, stopped, reversed, and stopped repeatedly for a predetermined time. During this time, the washing power of the clothes is enhanced as the clothes are repeatedly lifted and dropped by the baffles 23.

[0034] After the washing process, the control device 13 executes the dewatering process. In the dewatering process, the drum 21 is initially rotated at a low speed so that the clothes do not stick to it. At the low speed, the clothes that have absorbed water in the washing process are lifted by the baffles 23 as the drum 21 rotates, and spread out on the inner surface of the drum 21 as they fall. Once the clothes begin to spread out, the rotation speed of the drum 21 is gradually increased to make the clothes stick to the drum 21. Once the clothes are stuck to the drum 21, the rotation speed of the drum 21 is increased, passing through the resonant rotation speed range of the outer tub 17, and reaching a steady rotation speed to centrifugeally dewater the water contained in the clothes. The resonant rotation speed of the outer tub 17 is the value obtained by converting the natural frequency (Hz) at which the outer tub 17 resonates into rotation speed (rpm), and in this embodiment, the outer tub 17 is assumed to have three types of resonant rotation speeds r1, r2, and r3.

[0035] After the dewatering process, the control device 13 executes the rinsing process. In the rinsing process, 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, the detergent container 33, and the front water supply hose 35 or the rear water supply hose 36. Also, as with the washing process, the amount of water supplied increases as the calculated amount of clothing increases. In the rinsing process, as with the washing process, the drum 21 repeats the operation of forward rotation, stopping, reverse rotation, and stopping. At this time, an agitation operation is performed for a predetermined time in which the clothing lifted by the baffle 23 falls.

[0036] Subsequently, the control device 13 repeats the dewatering and rinsing processes described above a predetermined number of times, and then proceeds to the final dewatering process.

[0037] If the drum-type washing machine has a drying function, the control device 13 performs 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 lower speed than during the washing process. During the drying process, while the drum 21 rotates at a low speed, warm air is blown onto the clothes inside the drum 21 from a blower unit (not shown) to dry the clothes while reducing wrinkles.

[0038] <Method for determining imbalance> Before describing the details of the dewatering process in this embodiment, we will now explain the method for determining imbalance in this embodiment. As described above, the dewatering process is a process in which the rotation speed of the drum 21, which has stopped after the washing and rinsing processes are completed, is gradually increased to a steady rotation speed, and the high-speed steady rotation speed is maintained for a predetermined time to dewater wet clothes, etc. In the region where the rotation speed of the drum 21 and the resonant rotation speed of the outer tub 17 coincide, 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 dewatering process, not only will excessive outer tub vibration and noise occur, but there is also a risk that the outer tub 17 may collide with the housing 1.

[0039] Therefore, if the control device 13 detects an imbalance in the early stages of the dewatering process, before the drum rotation speed exceeds the outer tub resonant rotation speed range (shaded area in Figure 3A), it controls the rotation of the motor 22 to temporarily stop the rotation of the drum 21, perform a loosening operation at a low speed, and then increase the rotation speed of the drum 21 again to retry the dewatering process.

[0040] Therefore, the control device 13 in this embodiment uses a method to determine whether or not there is an imbalance based on the rotational pulsation of the drum 21 (hereinafter simply referred to as "rotational pulsation determination") and a method to determine whether or not there is an imbalance based on the detected value of the vibration sensor 28 (hereinafter simply referred to as "vibration determination") in combination to determine whether or not there is an imbalance at the initial stage of the dewatering process. If an imbalance is detected, the device corrects the imbalance by retrying the process and then increases the drum rotation speed to a steady rotation speed.

[0041] Rotational pulsation detection is a detection method used in the low-speed rotation range where the rotational speed of the drum 21 is relatively low (for example, 100 rpm or less), and mainly determines whether there is a relatively large imbalance caused by the uneven distribution or overlapping of clothing stuck to the inner surface of the drum 21. In this rotational pulsation detection, an imbalance is determined to have occurred when the rotational pulsation of the drum 21, calculated based on the output of the Hall element of the motor 22, is greater than or equal to a predetermined threshold Ta.

[0042] Here, rotational pulsation is the difference between the maximum and minimum rotational speeds when the drum 21 completes one rotation. The threshold value Ta is a value selected from a set of values ​​pre-registered in the control device 13 (for example, Ta1, Ta2, Ta3 (where Ta1 > Ta2 > Ta3)). Note that Ta1, which is the initial value of the threshold value Ta, is the largest threshold value and may be replaced with smaller threshold values ​​such as Ta2 or Ta3 depending on the situation.

[0043] The vibration detection method is an unbalance detection method used in the high-speed rotation range where the rotation speed of the drum 21 is relatively high, and it determines whether or not there is a relatively small unbalance. In this vibration detection, it is determined that an unbalance has occurred when the outer tank vibration value detected by the vibration sensor 28 is equal to or greater than a predetermined threshold Tb. The threshold Tb used here is a value determined according to the specifications of the outer tank 17, and the control device 13 has multiple thresholds Tb (for example, Tb1, Tb2, Tb3) that are switched according to the rotation speed of the drum 21 pre-registered.

[0044] The reason for switching the threshold Tb according to the rotational speed of the drum 21 is as follows: The outer tub 17 has the characteristic that the direction in which it is most prone to vibration differs for each resonant rotational speed. Therefore, when performing vibration determination in this embodiment, the control device 13 calculates the amount of outer tub vibration in the direction in which it is most prone to vibration at the current rotational speed of the drum 21, based on the three-axis vibration values ​​input from the vibration sensor 28, and compares it with the threshold Tb for that vibration direction, thereby efficiently determining the occurrence of an imbalance.

[0045] <Dehydration process> Next, the specific rotational movement of the drum 21 during the dewatering process will be explained with reference to Figures 3A and 3B.

[0046] If there is no imbalance, in the dewatering process of this embodiment, as illustrated in Figure 3A, the rotational speed of the drum 21 is gradually increased to pass through a resonant rotational speed range (e.g., 100-400 rpm) where the vibrational displacement of the outer tub 17 increases, and then the dewatering is determined to be complete when the drum is operated at a steady rotational speed (e.g., 900 rpm) for a predetermined time (e.g., 80 seconds).

[0047] In this example, the rotational pulsation detected in the rotational pulsation detection section below 100 rpm was smaller than a predetermined threshold Ta. Therefore, no imbalance was detected by the rotational pulsation detection, and the process moved to the drum rotation speed in the vibration detection section without retrying. Furthermore, in the resonant rotation speed range included in the vibration detection section, the detected value of the vibration sensor 28 at each resonant rotation speed was smaller than a predetermined threshold Tb. Therefore, no imbalance was detected by the vibration detection, and the drum rotation speed was increased to the steady-state rotation speed without retrying, after which the dewatering process was terminated.

[0048] On the other hand, if there is an imbalance, in order to prevent collision between the outer tub 17 and the housing 1, and to prevent an increase in vibration and noise at steady rotation speeds, in the dewatering process of this embodiment, as illustrated in Figure 3B, two retries are performed to improve the imbalance, and then the drum rotation speed is increased to steady rotation speed. Specifically, since the rotational pulsation detected in the rotational pulsation judgment section below 100 rpm was greater than a predetermined threshold Ta, an imbalance is detected by rotational pulsation judgment, and the first retry is performed to improve the imbalance. In addition, in the resonant rotation speed range of the outer tub 17, the detected value of the vibration sensor 28 at a certain resonant rotation speed was greater than a predetermined threshold Tb, so an imbalance is detected by vibration judgment, and the second retry is performed to further improve the imbalance. After the second retry, since the imbalance has been sufficiently improved, the dewatering process can be completed using the same procedure as in the example in Figure 3A.

[0049] Here, we consider the significance of the threshold Ta for rotational pulsation detection and the threshold Tb for vibration detection.

[0050] Immediately after the start of the spin cycle, the clothes are heavy and contain a lot of water, making it easy for the weight distribution of the clothes in the drum 21 to become uneven (unbalanced). If a strict unbalance detection is performed in this state, it may be easily judged as unbalanced, potentially leading to repeated retries. Therefore, the initial value of the threshold Ta for rotational pulsation detection (Ta1) is set to be relatively high, allowing the spin cycle to continue at a relatively low drum rotation speed unless the unbalance is severe.

[0051] On the other hand, even if the unbalance is small enough to pass through the rotational pulsation detection section, if an unbalance that is unsuitable for high-speed rotation at the resonant rotational speed is overlooked, there is a risk that the outer tank 17 and the housing 1 may collide, or that vibration and noise may increase. Therefore, it is necessary to detect even minor unbalances without fail and to perform appropriate retries. For this reason, the threshold Tb for the vibration detection section is set to be small so that unbalances unsuitable for high-speed rotation at the resonant rotational speed can be detected appropriately.

[0052] Incidentally, when spinning a single garment, which is highly absorbent and relatively small, and therefore prone to large imbalances, even if it can pass through the rotational pulsation detection section using a larger threshold Ta, it has the characteristic of being prone to repeated unbalance detection (and subsequent retries) in the vibration detection section using a smaller threshold Tb. As retries are repeated, the weight of the garment decreases significantly in the initial stages of the spinning process compared to before spinning, diminishing the significance of setting a larger threshold Ta for rotational pulsation detection. Instead, the disadvantages of not performing strict unbalance detection in the rotational pulsation detection section (for example, prolonged spinning process or abnormal shutdown due to frequent retries in the vibration detection section) become more pronounced.

[0053] Therefore, in this embodiment, the threshold Ta for determining rotational pulsation is gradually lowered according to the progress of the dewatering process before the retry. This allows for a more appropriate determination of whether or not there is an imbalance when retrying the dewatering process for a single garment, using the lowered threshold Ta.

[0054] <<Flowchart>> Next, using the flowchart in Figure 4, we will explain in detail the procedure of the dewatering process in this embodiment, assuming that one garment with a large imbalance is being dewatered.

[0055] First, in step S11, the control device 13 controls the rotational speed of the motor 22 to gradually increase the rotational speed of the drum 21.

[0056] Next, in step S12, the control device 13 performs an unbalance determination depending on whether the rotational pulsation of the drum 21 in the rotational pulsation determination section is smaller than the threshold Ta for rotational pulsation determination. If the requirement is met, the device proceeds to step S15; otherwise, it proceeds to step S13. The initial value of the threshold Ta is threshold Ta1, which is the largest of the multiple thresholds Ta provided.

[0057] In step S13, the control device 13 stops the rotation of the motor 22 and also stops the rotation of the drum 21. As a result, the clothes that have stuck to the inner surface of the drum 21 due to centrifugal force fall off.

[0058] 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).

[0059] Meanwhile, in step S15, the control device 13 controls the rotational speed of the motor 22 to gradually increase the rotational speed of the drum 21 toward the first resonant rotational speed r1 (e.g., 180 rpm) of the outer tank 17.

[0060] In step S16, the control device 13 determines whether the vibration value of the outer tank 17 before reaching the first resonant rotational speed r1 is smaller than the vibration determination threshold Tb1. If the requirement is met, the device proceeds to step S17; otherwise, it proceeds to step S13. The vibration value used in this step is the vibration value in the direction in which the outer tank 17 is most likely to vibrate at the first resonant rotational speed r1, and the threshold Tb1 is a threshold value prepared as the threshold Tb for that direction.

[0061] In step S17, the control device 13 controls the rotational speed of the motor 22 to gradually increase the rotational speed of the drum 21 toward the second resonant rotational speed r2 (e.g., 240 rpm) of the outer tank 17.

[0062] In step S18, the control device 13 determines whether the vibration value of the outer tank 17 before reaching the second resonant rotational speed r2 is smaller than the vibration determination threshold Tb2. If the requirement is met, the process proceeds to step S1a; otherwise, the process proceeds to step S19. The vibration value used in this step is the vibration value in the direction in which the outer tank 17 is most likely to vibrate at the second resonant rotational speed r2, and the threshold Tb2 is a threshold value prepared as the threshold Tb for that direction.

[0063] In step S19, the control device 13 lowers the threshold Ta for rotational pulsation determination from the initial value Ta1 to Ta2 (however, Ta1 > Ta2), and then proceeds to step S13. As a result, a threshold Ta2 smaller than the threshold Ta1 is used for subsequent rotational pulsation determination.

[0064] In step S1a, the control device 13 controls the rotational speed of the motor 22 to gradually increase the rotational speed of the drum 21 toward the third resonant rotational speed r3 (e.g., 360 rpm) of the outer tank 17.

[0065] In step S1b, the control device 13 determines whether the vibration value of the outer tank 17 before reaching the third resonant rotational speed r3 is smaller than the vibration determination threshold Tb3. If the requirement is met, the device proceeds to step S1d; otherwise, it proceeds to step S1c. The vibration value used in this step is the vibration value in the direction in which the outer tank 17 is most likely to vibrate at the third resonant rotational speed r3, and the threshold Tb3 is a threshold value prepared as the threshold Tb for that direction.

[0066] In step S1c, the control device 13 lowers the threshold Ta for rotational pulsation determination from the previous value to Ta3 (however, Ta1 > Ta2 > Ta3), and then proceeds to step S13. As a result, a threshold Ta3, which is smaller than thresholds Ta1 and Ta2, is used for subsequent rotational pulsation determination.

[0067] In step S1d, the control device 13 controls the rotational speed of the motor 22 to gradually increase the rotational speed of the drum 21 toward a steady rotational speed (e.g., 900 rpm). Then, after continuing dewatering at the steady rotational speed for a predetermined time, the dewatering operation is terminated.

[0068] As described above, in this embodiment, the threshold value Ta used in subsequent rotational pulsation determination is gradually lowered according to the timing of detection of unbalance in the resonant rotational speed range (i.e., taking into account the amount of water removed in the dewatering process before the retry). As a result, if the threshold value Ta were constant, unbalances that could only be detected in the vibration determination section with high drum rotational speeds can now be detected earlier in the rotational pulsation determination section with low drum rotational speeds.

[0069] Therefore, according to this embodiment, by retrying, the accuracy of detecting unbalance in the low-speed rotation range for a single garment with reduced weight can be improved, and by performing dewatering when the unbalance is small, the increase in retries in the resonant rotation speed range of the outer tub 17 can be suppressed, preventing the operation from ending without completing dewatering. [Examples]

[0070] Next, a drum-type washing machine 100 according to Embodiment 2 of the present invention will be described using Figures 5, 6A, and 6B. Note that common points with Embodiment 1 will not be explained again.

[0071] This embodiment differs from Embodiment 1 in that, if an imbalance is detected by vibration judgment during the dewatering process before a retry, a period is provided during the retry in which the drum 21 is rotated at a speed lower than the resonant rotation speed at which an imbalance has been detected before.

[0072] The specific spin-drying operation of the drum-type washing machine 100 of this embodiment is shown in the flowchart of Figure 5. Note that the processes unique to this embodiment are steps S25-S26, S29-S2a, and S2e-S2f in Figure 5, while the other processes correspond to steps S11-S1d in Figure 4. Therefore, the significance of the processes unique to this embodiment will be explained in detail below.

[0073] Step S25 is a process performed if 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 Tb1 for the first resonant rotation speed r1 during the dewatering before the retry. If the requirements are met, the process proceeds to step S26; otherwise, the process proceeds to step S27 (corresponding to step S15).

[0074] In step S26, the control device 13 controls the rotational speed of the motor 22 to rotate the drum 21 for a certain period of time at a rotational speed lower than the resonant rotational speed r1 of the outer tub 17 (e.g., 180 rpm) (e.g., 160 rpm) (see Figure 6A). During this period, water is removed from the clothes, and the unbalance is reduced, making it more likely that the unbalance determination using the threshold Tb1 in step S28 (corresponding to step S16) will not detect an unbalance.

[0075] Furthermore, step S29 is a process that is performed if 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 Tb2 for the second resonant rotation speed r2 during the dewatering before the retry. If the requirements are met, the process proceeds to step S2a; otherwise, the process proceeds to step S2b (corresponding to step S17).

[0076] In step S2a, the control device 13 controls the rotational speed of the motor 22 to rotate the drum 21 for a certain period of time at a rotational speed lower than the resonant rotational speed r2 of the outer tub 17 (e.g., 240 rpm) (e.g., 220 rpm) (see Figure 6B). During this period, water is removed from the clothes, and the unbalance is reduced, making it more likely that the unbalance determination using the threshold Tb2 in step S2c (corresponding to step S18) will not detect an unbalance.

[0077] Furthermore, step S2e is a process that is performed if 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 Tb3 for the third resonant rotation speed r3 during the dewatering before the retry. If the requirements are met, the process proceeds to step S2f; otherwise, the process proceeds to step S2g (corresponding to step S1a).

[0078] In step S2f, the control device 13 controls the rotational speed of the motor 22 to rotate the drum 21 for a certain period of time at a rotational speed lower than the resonant rotational speed r3 of the outer tub 17 (e.g., 360 rpm) (e.g., 340 rpm) (see Figure 6C). During this period, water is removed from the clothes, and the unbalance is reduced, making it more likely that the unbalance determination using the threshold Tb3 in step S2h (corresponding to step S1b) will not detect an unbalance.

[0079] As described above, according to this embodiment, it is possible to check whether an unbalance has been detected in the resonant rotation speed range before retrying, and if an unbalance has been detected, the drum 21 is rotated for a certain period of time at a rotation speed lower than the resonant rotation speed at which the unbalance was detected, thereby promoting water removal from the clothes and reducing the unbalance, and thus suppressing the increase in vibration and noise at the resonant rotation speed during retrying. [Examples]

[0080] Next, a drum-type washing machine 100 according to Embodiment 3 of the present invention will be described using Figure 7. Note that common points with Embodiment 1 will not be explained again.

[0081] This embodiment differs from Embodiment 1 in that it switches the processing content performed before the loosening operation in step S35 (corresponding to step S14) depending on the timing of the detection of imbalance, and switches the length of the dewatering time at the steady rotation speed depending on whether or not an imbalance has been detected by vibration determination.

[0082] The specific spin-drying operation of the drum-type washing machine 100 in this embodiment is shown in the flowchart of Figure 7. Note that the processes unique to this embodiment are steps S33-S34 and S3g-S3i in Figure 7, while the other processes correspond to the processes in steps S11-S1d in Figure 4. Therefore, the significance of the processes unique to this embodiment will be explained in detail below.

[0083] Step S33 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 Embodiment 1, the control device 13 stops the rotation of the motor 22 and also stops the rotation of the drum 21. However, when this step is taken, unlike when step S3b, which is also a drum rotation stopping step, is taken, step S34 is performed before the loosening operation of step S35 (corresponding to step S14) is performed.

[0084] In step S34, the control device 13 opens the water supply valve 31 and pours water into the drum 21. If an imbalance is detected in step S32 or step S37 (i.e., if an imbalance is detected in a region where the rotation speed of the drum 21 is relatively low), the clothes have not been dewatered very far, so pouring water into the drum 21 at this point does not cause much disadvantage to subsequent dewatering. On the other hand, increasing the water content of the clothes makes it easier to move the clothes and untangle them during the loosening operation (step S35), which has the great advantage of making it easier to correct the imbalance.

[0085] Furthermore, if an imbalance is detected in step S39 (corresponding to step S18) or step S3d (corresponding to step S1b), step S34 (drum water filling) is skipped because, at the time of step S39 or step S3d, the clothes have already undergone considerable dewatering, and filling the drum 21 with water at this point would actually prolong the time required to complete the dewatering process.

[0086] In step S3g, the control device 13 determines whether it has previously detected an imbalance through vibration detection (steps S37, S39, S3d). If the requirements are met, it proceeds to step S3i; otherwise, it proceeds to step S3h.

[0087] In step S3i, the control device 13 changes the dewatering time at the steady speed from the normal setting (e.g., 80 seconds) to a shorter setting (e.g., 40 seconds), and terminates the dewatering operation once this changed setting time has elapsed. This is because repeated dewatering in the high-speed rotation range has already progressed the dewatering compared to when there were no retries, so shortening the dewatering time at the steady speed is thought to have little adverse effect on dewatering. Furthermore, if the dewatering time at the steady speed is not shortened, the time required to complete the dewatering operation may be significantly longer compared to when there are no retries.

[0088] In particular, when only one garment is being dewatered, it tends to stick to the inner surface of the drum 21, making it easier for centrifugal force to act on the garment and thus easier to dewater compared to normal washing. Therefore, when dewatering a single garment, sufficient dewatering can be achieved even if the operating time at a steady rotation speed is shortened, thereby suppressing an increase in the total dewatering time.

[0089] On the other hand, in step S3h, the control device 13 maintains the dewatering time at the steady rotation speed at a normal set value (for example, 80 seconds), and terminates the dewatering operation once this set time has elapsed.

[0090] As described above, according to this embodiment, by changing the method of correcting the unbalance based on the rotation speed of the drum 21 at which the unbalance is detected, the unbalance can be corrected according to the condition of a single garment, and the increase in operating time due to retries can be suppressed. [Explanation of symbols]

[0091] 100... Drum-type washing machine, 17...outer tank, 21... Drums, 22...motor, 28…Vibration sensor,

Claims

1. The casing and An outer tank installed inside the housing, A drum capable of storing clothes is rotatably installed inside the outer tank, A motor that rotates the drum, A water supply valve for supplying water to the drum, A vibration sensor for detecting vibrations of the outer tank, In the dewatering process, a control device controls the motor to retry the dewatering process when it detects an imbalance in the clothes inside the drum based on rotational pulsation determination, which determines whether or not there is an imbalance based on the rotational pulsation of the drum, or vibration determination, which determines whether or not there is an imbalance based on the vibration of the outer tub. A drum-type washing machine equipped with, The rotational pulsation determination is a determination that detects an imbalance when the rotational pulsation of the drum exceeds a first threshold. The vibration determination is a determination that detects an imbalance when the vibration of the outer tank exceeds a second threshold when the rotational speed of the drum is the resonant rotational speed of the outer tank. The drum-type washing machine is characterized in that the first threshold is changed to a smaller threshold as the rotational speed of the drum increases when the vibration of the outer tub exceeds the second threshold.

2. In the drum-type washing machine according to claim 1, The control device, when it detects an imbalance based on the vibration determination, is characterized in that, during a retry of the spin cycle, it rotates the drum for a predetermined time at a rotation speed lower than the rotation speed of the drum when the vibration of the outer tub exceeds the second threshold.

3. 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 an imbalance is detected, it supplies water to the drum and then retrys the spin cycle, and if the rotation speed of the drum is high when an imbalance is detected, it does not supply water to the drum and retrys the spin cycle.

4. In the drum-type washing machine according to claim 1, The control device is characterized in that, when an imbalance is detected by the vibration determination, it shortens the time the drum is rotated at a steady speed during a retry of the spin cycle compared to when an imbalance is not detected by the vibration determination.

Images