washing machine

Abstract

To provide a washing machine capable of preventing bubble generation during dewatering operation.SOLUTION: The dewatering operation of the present washing machine includes the steps of full-scale dewatering (S3) for rotating a rotary tub at a high-speed pre-set revolution, pre-dewatering (S1) for rotating the rotary tub at a revolution lower than that during full-scale dewatering, which is performed before the full-scale dewatering, and draining (S2) for draining water from a water tank while stopping the rotation of the rotary tub, which is performed between the pre-dewatering and the full-scale dewatering.SELECTED DRAWING: Figure 1

Description

Technical Field

[0006]

[0001] The present invention relates to a washing machine.

Background Art

[0002] The washing tub in a washing machine has a double structure of a water tank for storing water during washing and a rotating tub disposed inside the water tank. In recent drum-type washing machines and the like, in order to achieve miniaturization, there may be a design that reduces the diameter difference between the water tank and the rotating tub (the outer surface of the drum is brought closer to the inner surface of the water tank). In this case, the problem of foam generation during the dehydration operation becomes prominent.

[0003] At the initial stage of the dehydration operation, a large amount of washing water (water containing detergent components) is wrung out from the laundry. At this time, if the drainage of the washing water from the water tank cannot keep up and the washing water comes into contact with the rotating tub, a large amount of foam may be generated in the washing tub. Then, the foam existing between the water tank and the rotating tub becomes a rotational resistance, and a situation where it is difficult to increase the rotational speed of the rotating tub occurs. Note that such a problem of foam generation exists not only in drum-type washing machines but also in vertical-type washing machines.

[0004] Patent Document 1 discloses detecting foam generation based on the rotational speed of the rotating tub, and when foam generation is detected, performing a process of eliminating the foam (such as temporarily stopping dehydration and performing soaking and rinsing).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the above Patent Document 1, it is difficult to eliminate the generation of foam itself, and there is a problem that it takes time to eliminate the foam when it occurs.

[0007] This invention has been made in view of the above problems, and aims to provide a washing machine that can prevent foam generation during the spin-drying operation. [Means for solving the problem]

[0008] To solve the above problems, the present invention provides a washing machine having a double-layered washing tub comprising a water tank for storing water during washing and a rotating tub disposed inside the water tank, characterized in that the dewatering process includes: a main dewatering process in which the rotating tub is rotated at a first set rotation speed; a pre-dewatering process performed before the main dewatering process in which the rotating tub is rotated at a second set rotation speed which is lower than the first set rotation speed; and a draining process performed between the pre-dewatering process and the main dewatering process in which the rotation of the rotating tub is stopped and water is drained from the water tank.

[0009] With the above configuration, by performing a pre-dewatering process and a draining process before the main dewatering process, it is possible to reliably prevent the generation of foam during the dewatering operation.

[0010] Furthermore, the washing machine may be configured to check the drainage environment of the washing machine at the start of the spin-drying operation, and if it is determined that the drainage environment is poor, it will perform the pre-spin-drying process, the drainage process, and the main spin-drying process. If it is determined that the drainage environment is good, it will perform only the main spin-drying process.

[0011] With the above configuration, the pre-dewatering process (and drainage process) is performed only when there is a possibility of foam generation (situations with poor drainage environment), and the pre-dewatering process can be omitted when there is no possibility of foam generation (situations with good drainage environment), thus avoiding an undesirable increase in the time required for dewatering operation.

[0012] Furthermore, the washing machine may be configured to check the amount of laundry at the start of the spin-drying cycle, and if it is determined that the amount of laundry is greater than or equal to a predetermined amount, it may perform the pre-spin-drying step, the draining step, and the main spin-drying step. If it is determined that the amount of laundry is less than a predetermined amount, it may perform only the main spin-drying step.

[0013] With the above configuration, the pre-spinning process (and draining process) is performed only when there is a possibility of foam generation (when there is a large amount of laundry), and the pre-spinning process can be omitted when there is no possibility of foam generation (when there is a small amount of laundry), thus avoiding an undesirable increase in the time required for the spinning operation.

[0014] Furthermore, the washing machine may be configured such that, during the pre-spinning process, if the detected water level in the washing tub reaches a predetermined level, the pre-spinning process is interrupted and a draining process is performed. If the pre-spinning process is completed without the detected water level in the washing tub reaching a predetermined level, the draining process is omitted and the main spinning process is performed.

[0015] With the above configuration, if there is a possibility of foam generation due to the continuation of the pre-dewatering process, foam generation can be reliably prevented by interrupting the pre-dewatering process and performing the drainage process. If the pre-dewatering process is completed normally without the possibility of foam generation, the drainage process can be omitted, thereby shortening the dewatering operation time. [Effects of the Invention]

[0016] The washing machine of the present invention has the effect of reliably preventing the generation of foam during the spin cycle by performing a pre-spin cycle and a draining cycle before the main spin cycle. [Brief explanation of the drawing]

[0017] [Figure 1] This is a flowchart showing the control of the spin-drying operation of the washing machine in Embodiment 1. [Figure 2] This is a flowchart showing the control of the spin-drying operation of the washing machine in Embodiment 2. [Figure 3]It is a flowchart showing the control of the dehydration operation of the washing machine in Embodiment 3. [Figure 4] It is a flowchart showing the control of the dehydration operation of the washing machine in Embodiment 4.

Modes for Carrying Out the Invention

[0018] 〔Embodiment 1〕 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is particularly suitable for application to a drum-type washing machine in which the diameter difference between the water tank and the rotary tub (drum) is reduced. However, the present invention is not limited to drum-type washing machines and can also be applied to vertical washing machines.

[0019] The washing machine according to the present invention (hereinafter, this washing machine) is characterized in that it performs control for preventing the generation of bubbles during the dehydration operation. FIG. 1 is a flowchart showing the control of the dehydration operation of the washing machine in Embodiment 1. As shown in FIG. 1, the dehydration operation in this washing machine is performed in a procedure consisting of three steps: a pre-dehydration step, a drainage step, and a main dehydration step.

[0020] The pre-dehydration step (S1) is the step performed first in the dehydration operation, and the rotary tub of this washing machine is rotated at a relatively low speed (for example, the set rotation speed (the second set rotation speed) is 400 rpm). At the initial stage of the dehydration operation, a large amount of washing water is squeezed out from the laundry. However, in the pre-dehydration step, by keeping the rotation speed lower (than the main dehydration step described later), it is possible to suppress the discharge of a large amount of washing water in a short period of time. As a result, it is possible to avoid a situation where the drainage from the washing tub cannot keep up with the washing water discharged from the laundry. That is, during the pre-dehydration step, it is possible to avoid (or significantly suppress) the contact of the washing water with the rotary tub, and prevent the generation of bubbles.

[0021] The pre-dehydration process ends when the rotating tank reaches the set rotation speed or after a certain period of time (preferably, a time sufficient to deem that the rotation speed has reached the set rotation speed). After the pre-dehydration process ends, the rotation of the rotating tank is terminated temporarily, and a drainage process (S2) is performed to drain all the drained washing water from the washing tank. The drainage process ends when the water level sensor provided in the washing tank detects that the water level in the washing water is at the no-water level.

[0022] Thus, by ending the pre-dehydration process based on predetermined conditions (rotation speed or time), the generation of bubbles during the pre-dehydration process can be surely prevented. That is, if the drainage environment from the washing tank is extremely poor, by continuing the pre-dehydration process for a long time, there is a possibility that the washing water contacts the rotating tank during the pre-dehydration process and bubbles are generated. In contrast, if the pre-dehydration process is ended based on predetermined conditions, it is possible to avoid the contact of the washing water with the rotating tank during the pre-dehydration process. And by draining in the drainage process, the generation of bubbles in the subsequent main dehydration process can also be prevented.

[0023] After the drainage process ends, the main dehydration process (S3) is performed. In the main dehydration process, the rotating tank of this washing machine is rotated at a higher speed than during the pre-dehydration process (for example, the set rotation speed (the first set rotation speed) is 1000 rpm). In the main dehydration process, since the amount of washing water contained in the laundry has decreased, even if the rotating tank is rotated at a high speed, a large amount of washing water will not be discharged in a short period of time, and the generation of bubbles can also be prevented.

[0024] Incidentally, the set rotation speed of the rotating tank during the dehydration operation is usually set to be increased step by step at a preset timing. For example, in this main dehydration process, the set rotation speed is sequentially increased to 400 rpm, 600 rpm, 800 rpm, and 1000 rpm. Therefore, the above-mentioned first set rotation speed (1000 rpm) of the main dehydration process refers to the final set rotation speed.

[0025] 〔Embodiment 2〕 Embodiment 1 described a control method that prevents foam generation by performing a pre-dehydration step before the main dehydration step during the dehydration operation. However, foam generation during the dehydration operation does not necessarily occur simply because the pre-dehydration step is not performed. For example, if the washing machine has sufficient drainage capabilities, foam may not normally be generated even without a pre-dehydration step, but foam may be generated only if the drainage environment is poor for some reason. For example, in a drum-type washing machine, the drainage environment deteriorates due to the accumulation of lint in the lint filter. In such cases, if a pre-dehydration step is performed when the drainage environment is good and there is no possibility of foam generation, the time required for the dehydration operation will increase undesirably.

[0026] In the washing machine according to this second embodiment, a pre-spinning process is performed according to the drainage environment of the washing machine. Figure 2 is a flowchart showing the control of the spinning operation of the washing machine in this second embodiment.

[0027] In this flow, the drainage environment of the washing machine is checked at the start of the spin cycle (S11). In washing machines, water is drained both before the spin cycle and after the rinse cycle. Therefore, the drainage environment can be determined by measuring the drainage time after the wash or rinse cycle. For example, if the drainage time is less than a predetermined time, it can be determined that the drainage environment is good, and if the drainage time exceeds the predetermined time, it can be determined that the drainage environment is poor.

[0028] During the dewatering operation, if it is determined that the drainage environment is poor (YES in S11), the three steps (S1-S3) described in Embodiment 1—the pre-dewatering step, the drainage step, and the main dewatering step—are performed. On the other hand, if it is determined that the drainage environment is good (NO in S11), the pre-dewatering step and the drainage step described in Embodiment 1 are omitted, and only the main dewatering step (S3) is performed.

[0029] This allows the pre-spinning process (and draining process) to be performed only when there is a possibility of foam generation, and the pre-spinning process can be omitted when there is no possibility of foam generation, thus avoiding an unwanted increase in the time required for the spin-drying operation. In other words, this washing machine can improve the overall operational efficiency by performing the pre-spinning process only when necessary.

[0030] Furthermore, if multiple spin-drying cycles are performed in a single wash cycle, the S11 judgment only needs to be made during the first spin-drying cycle, and subsequent spin-drying cycles shall be performed in the same manner as the first spin-drying cycle. In other words, if a pre-spin-drying process is performed during the first spin-drying cycle, the pre-spin-drying process shall also be performed during subsequent spin-drying cycles, and if the pre-spin-drying process is omitted during the first spin-drying cycle, the pre-spin-drying process shall also be omitted during subsequent spin-drying cycles.

[0031] [Embodiment 3] This third embodiment shows a modified control in which the pre-dehydration process is performed only when there is a possibility of foam generation. Figure 3 is a flowchart showing the control of the dehydration operation of this washing machine in this third embodiment.

[0032] In this flow, the amount of laundry is checked at the start of the spin cycle (S21). Automatic washing machines automatically determine the amount of water and detergent to be added, so the weight of the laundry is measured before the wash cycle starts. In this washing machine, it is possible to determine whether the amount of laundry is above a predetermined amount by measuring the weight of the laundry.

[0033] During the spin-drying operation, if it is determined that "the amount of laundry exceeds a predetermined amount" (YES in S21), the three steps (S1-S3) described in Embodiment 1—the pre-spin-drying step, the draining step, and the main spin-drying step—are performed. In other words, when there is a large amount of laundry, a large amount of wash water is squeezed out of the laundry in the initial stages of spin-drying, increasing the likelihood of foam generation. The pre-spin-drying step prevents foam generation.

[0034] On the other hand, if it is determined that the amount of laundry is less than a predetermined amount (NO in S21), the pre-spinning and draining processes described in Embodiment 1 are omitted, and only the main spinning process (S3) is performed. In other words, when the amount of laundry is small, the amount of wash water contained in the laundry is also small, so a large amount of wash water is not squeezed out of the laundry in the initial stages of spinning, and the possibility of foam generation is reduced. For this reason, if the amount of laundry is less than a predetermined amount and it can be considered that there is no possibility of foam generation, the pre-spinning process can be omitted.

[0035] As a result, the pre-dewatering process is performed only when there is a possibility of foam generation, and the pre-dewatering process can be omitted when there is no possibility of foam generation, thus avoiding an undesirable increase in the time required for dewatering. Furthermore, the control according to this third embodiment can also be performed in conjunction with the control according to the second embodiment. In this case, both the S11 step in Figure 2 and the S21 step in Figure 3 are checked, and if a YES check is made in either step, the pre-dewatering process and drainage process are performed. It is sufficient to perform the three steps (S1 to S3) of the initial dehydration process and the main dehydration process. If the result is NO in both steps, only the main dehydration process (S3) needs to be performed.

[0036] [Embodiment 4] In the control mechanisms described in embodiments 1 to 3 above, a draining step is performed before the main dewatering step when a pre-dewatering step is carried out. This is a measure to prevent foam from being generated during the pre-dewatering step due to an excess of wash water being squeezed out. However, if the amount of wash water squeezed out during the pre-dewatering step is within the expected range, the draining step can be omitted.

[0037] In the washing machine according to this fourth embodiment, the washing water squeezed out during the pre-spinning process is detected, and the draining process is omitted depending on the result. Figure 4 is a flowchart showing the control of the spinning operation of this washing machine in the fourth embodiment.

[0038] In this flow, during the pre-spinning process (S1), a water level sensor detects the water level in the washing tub. If the water level reaches a predetermined level (YES in S31), the pre-spinning process is interrupted and the draining process (S2) is performed. The predetermined water level here refers to the water level just before the washing water comes into contact with the rotating tub. This ensures that foam generation is reliably prevented by interrupting the pre-spinning process and performing the draining process when the detected water level in the washing tub reaches the predetermined level.

[0039] On the other hand, if the pre-dewatering process is completed without the water level reaching a predetermined level (NO in S31), the draining process (S2) can be omitted and the main dewatering process (S3) can be performed. In this case, the pre-dewatering process is completed when the rotating tank reaches a set rotation speed or after a certain period of time has elapsed, similar to Embodiment 1.

[0040] This ensures that if there is a possibility of foam generation due to the continuation of the pre-dewatering process, the pre-dewatering process can be interrupted and the draining process performed to reliably prevent foam generation. If the pre-dewatering process is completed normally without any possibility of foam generation, the draining process can be omitted to shorten the dewatering operation time. Furthermore, the control according to this embodiment 4 can also be implemented in conjunction with the control according to embodiments 2 and 3.

[0041] The embodiments disclosed herein are illustrative in all respects and are not intended to be restrictive. Therefore, the technical scope of the present invention is not construed solely by the embodiments described above, but is defined by the claims. This includes all modifications within the meaning and scope of the equivalents of the claims.

Claims

1. A washing machine having a double structure comprising a water tank for holding water during washing and a rotating drum disposed inside the water tank, As part of the dehydration process, This dewatering process involves rotating the aforementioned rotating tank at a first set rotation speed, A pre-dewatering step is performed before the main dewatering step, in which the rotating tank is rotated at a second set rotation speed which is lower than the first set rotation speed, The process includes a draining step performed between the pre-dewatering step and the main dewatering step, which stops the rotation of the rotating tank and drains water from the tank. At the start of the spin cycle, check the drainage environment of the washing machine. A washing machine characterized in that, if the drainage environment is determined to be poor, the pre-dehydration step, the drainage step, and the main dehydration step are performed, and if the drainage environment is determined to be good, only the main dehydration step is performed.

2. A washing machine having a double structure comprising a water tank for holding water during washing and a rotating drum disposed inside the water tank, As part of the dehydration process, This dewatering process involves rotating the aforementioned rotating tank at a first set rotation speed, A pre-dewatering step is performed before the main dewatering step, in which the rotating tank is rotated at a second set rotation speed which is lower than the first set rotation speed, The process includes a draining step performed between the pre-dewatering step and the main dewatering step, which stops the rotation of the rotating tank and drains water from the tank. Before starting the spin cycle, check the amount of laundry. A washing machine characterized in that, if the amount of laundry is determined to be greater than or equal to a predetermined amount, the pre-spinning step, the draining step, and the main spinning step are performed, and if the amount of laundry is determined to be less than a predetermined amount, only the main spinning step is performed.

3. A washing machine having a double structure comprising a water tank for holding water during washing and a rotating drum disposed inside the water tank, As part of the dehydration process, This dewatering process involves rotating the aforementioned rotating tank at a first set rotation speed, A pre-dewatering step is performed before the main dewatering step, in which the rotating tank is rotated at a second set rotation speed which is lower than the first set rotation speed, The process includes a draining step performed between the pre-dewatering step and the main dewatering step, which stops the rotation of the rotating tank and drains water from the tank. A washing machine characterized in that, during the execution of the pre-spinning process, if the detected water level in the washing tub reaches a predetermined water level, the pre-spinning process is interrupted and a draining process is performed, and if the pre-spinning process is completed without the detected water level in the washing tub reaching a predetermined water level, the draining process is omitted and the main spinning process is performed.

4. A washing machine having a double structure comprising a water tank for holding water during washing and a rotating drum disposed inside the water tank, As part of the dehydration process, This dewatering process involves rotating the aforementioned rotating tank at a first set rotation speed, A pre-dewatering step is performed before the main dewatering step, in which the rotating tank is rotated at a second set rotation speed which is lower than the first set rotation speed, The process includes a draining step performed between the pre-dewatering step and the main dewatering step, which stops the rotation of the rotating tank and drains water from the tank. A washing machine characterized in that the pre-dehydration step is omitted based on the possibility of foam generation.

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