WO2010058869A1

WO2010058869A1 - Washing machine and dehydrating method of the same

Info

Publication number: WO2010058869A1
Application number: PCT/KR2008/006894
Authority: WO
Inventors: Young-Jong Kim; Soon-An Park; Sang-Jun Lee
Original assignee: Lg Electronics Inc.
Priority date: 2008-11-21
Filing date: 2008-11-21
Publication date: 2010-05-27

Abstract

Disclosed are a washing machine and a dehydrating method of the same. The dehydrating method of a washing machine comprising: a casing that forms an appearance; an outer tub installed in the casing; an inner tub rotatably installed in the outer tub; and a motor for rotating the inner tub, comprises: preventing foam occurrence by non-consecutively increasing an rpm of the motor in an initial dehydration process; and when the motor rpm reaches a maximum rpm, maintaining the maximum rpm for a predetermined time. Foam occurrence at a low rpm region is reduced by removing water and detergent remaining on laundry by increasing an rpm of a motor step by step at the time of the initial dehydration process.

Description

WASHING MACHINE AND DEHYDRATING METHOD OF THE SAME

TECHNICAL FIELD

The present invention relates to a washing machine, and more particularly, to a washing machine capable of reducing foam occurrence at a low rpm region by removing water and detergent remaining on laundry by increasing an rpm of a motor step by step at the time of an initial dehydration process, and a dehydrating method of the same.

BACKGROUND ART

Generally, a washing machine uses an electric motor as a main driving force, and performs washing, rinsing, and dehydrating processes so as to remove contaminants on clothes by using water and detergent. The washing machine is composed of an electric motor serving as a driving apparatus, a mechanical part to transmit energy to laundry, a controller to control washing processes, a water supply apparatus to supply water, and a drain apparatus to drain water.

The washing machine is classified into a cylinder type, an agitator type, and a pulsator type based on a washing method. According to the agitator type, a wing-shaped agitator protruding from the center of a washing tub is rotated in right and left directions, thereby performing a washing process. According to the pulsator type, a washing process is performed by using water current occurring from rotation of a disc-shaped pulsator. And, according to the cylinder type, water, detergent and laundry are put in a drum having a plurality of protrusions, and then are horizontally rotated in a low speed, thereby performing a washing process by using an impact occurring as the laundry is lifted and dropped by the protrusions.

FIG. 1 is a sectional view schematically showing a part of a washing machine in accordance with the conventional art.

Referring to FIG. 1 , the conventional washing machine 10 comprises a casing 11 that forms an external shape of the washing machine 10, an outer tub 17 accommodated in the casing 11 , an inner tube 18 accommodated in the outer tub 17, and a suspension 19 having one end connected to an upper inner circumferential surface of the casing 11 , and having another end connected to a lower outer circumferential surface of the outer tub 17, for supporting the outer sub 17.

The washing machine 10 further comprises a door 14 disposed at an upper side of the washing machine 10 for opening and closing openings of the inner tub 18 and the outer tub 19, a water supply valve 16 disposed at one side of the casing 11 for supplying washing water to the inner tub 18 and the outer tub 17, a detergent box 13 disposed below the water supply valve 16 for supplying detergent, and a detergent box housing 12.

The water supply valve 16 is connected to the end of a water supply hose 15 connected to a faucet, and supplies washing water into the detergent box housing 12. Then, the washing water supplied into the detergent box housing 12 melts detergent contained in the detergent box 13, and then is supplied into the inner tub 18 and the outer tub 17 together with the detergent. FIG. 2 is a graph showing a relation between time and an rpm of a motor in a dehydration process of the washing machine of FIG. 1.

The conventional washing machine 10 has a problem that foam occurs in a dehydration process. Referring to FIG. 2, while consecutively increasing a rotation speed and an rpm of the inner tub 18 in a dehydration process after a washing process (refer to 'A' of FIG. 2), foam occurs due to a relative motion between the inner tub 18 and the outer tub 17. This causes a motor (not shown) to be restricted.

Furthermore, once the inner tub 18 reaches a maximum rotation speed, it takes about 10 seconds to maintain the maximum rotation speed or rpm (refer to 'B' of FIG. 2). This causes a difficulty in removing detergent from laundry. As a result, a rinsing process after the dehydration process is not smoothly performed due to the remaining detergent.

DISCLOSURE OF THE INVENTION Therefore, it is a first object of the present invention to provide a washing machine capable of reducing foam occurrence at a low rpm region by removing water and detergent by increasing an rpm of a motor step by step at the time of an initial dehydration process, and a dehydrating method of the same. It is a second object of the present invention to provide a washing machine capable of reducing vibration or noise occurring in a dehydration process by shortening time taken to maintain a motor rpm when the motor rpm that increases step by step reaches a resonant rpm, and a dehydrating method of the same. It is a third object of the present invention to provide a washing machine capable of enhancing a rinsing performance by removing water and detergent remaining on laundry after a rinsing process by sufficiently rotating a motor at a maximum rpm, and a dehydrating method of the same.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a dehydrating method of a washing machine comprising: a casing that forms an appearance; an outer tub installed in the casing; an inner tub rotatably installed in the outer tub; and a motor for rotating the inner tub, the method, comprising: preventing foam occurrence by non-consecutively increasing an rpm of the motor in the initial dehydration process; and when the motor rpm reaches a maximum rpm, maintaining the maximum rpm for a predetermined time.

In the step of preventing foam occurrence, the motor rpm is increased step by step. In the initial dehydration process after starting a dehydration process, the motor rpm is increased not consecutively but non-consecutively or step by step, thereby preventing foam occurrence between the inner tub and the outer tub.

In the step of preventing foam occurrence, the motor rpm is set to increase by at least ten steps. As the rpm or rotation speed of the motor is set to increase by a plurality of steps, foam occurrence is prevented, and dehydration effects are enhanced. Preferably, the ten-step speed profile is set to have a rotation speed that increases step-by-step.

In the step of preventing foam occurrence, the motor rpm is maintained for a predetermined time, and then is increased step by step into a larger level. When the motor rpm reaches a resonant rpm, time taken to maintain the resonant rpm is set to be shorter than time taken to maintain other rpm.

Here, the resonant rpm includes a first resonant rpm resulting from a horizontal motion of the washing machine, and a second resonant rpm resulting from a conical motion of the washing machine. Once the motor rpm reaches a resonant rpm, time taken to maintain the resonant rpm is set to be shorter than time taken to maintain other rpm.

This reduces vibration or noise that may occur during a dehydration process.

If the motor is rotated for a long time at the resonant rpm, resonance occurs to damage the washing machine. The motor is rotated at a maximum rpm for at least five minutes. As the time taken to rotate the motor at a maximum rpm is longer than that of the conventional art, detergent melted in dehydrating water is effectively discharged. Accordingly, a rinsing performance is enhanced.

According to another aspect of the present invention, there is provided a washing machine, comprising: a casing that forms an appearance; an outer tub installed in the casing; an inner tub rotatably installed in the outer tub; and a motor for rotating the inner tub, wherein an rpm of the motor is increased step by step in the initial dehydration process so as to prevent foam occurrence. Once the motor rpm reaches a maximum rpm, the motor is rotated at a maximum rpm for at least five minutes.

As aforementioned, the present invention provides a dehydrating method of a washing machine, in which the motor rpm is increased step by step in the initial dehydration process. This allows water and detergent remaining after a rinsing process to be effectively removed, and reduces foam occurrence at a low rpm region.

The present invention also provides a washing machine and a dehydrating method of the same capable of reducing vibration or noise, in which when the motor rpm reaches a resonant rpm, an rpm maintaining time of the motor is reduced so that the motor can be quickly out of the resonant region.

Furthermore, the present invention also provides a washing machine and a dehydrating method of the same capable of effectively removing water and detergent remaining on laundry after a rinsing process, and capable of enhancing a rinsing performance and a dehydration performance by sufficiently rotating a motor at a maximum rpm.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view schematically showing a part of a washing machine in accordance with the conventional art;

FIG. 2 is a graph showing a relation between time and an rpm of a motor in a dehydration process of the washing machine of FIG. 1 ;

FIG. 3 is a sectional view schematically showing a washing machine according to a first embodiment of the present invention; FIG. 4 is a flowchart showing a dehydrating method of the washing machine of FIG. 3; and

FIG. 5 is a graph showing a relation between time and an rpm of a motor in a dehydration process of the washing machine of FIG. 3.

MODES FOR CARRYING OUT THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

Hereinafter, a structure and operation of a washing machine and a dehydrating method according to a first embodiment of the present invention will be explained in more detail.

Explanations about the conventional well-known functions or configurations will be omitted so as to clarify the present invention.

FIG. 3 is a sectional view schematically showing a washing machine according to a first embodiment of the present invention.

Referring to FIG. 3, a washing machine 100 according to a first embodiment of the present invention comprises a casing 110 that forms an appearance, an outer tub 170 installed in the casing 110, an inner tub 180 rotatably installed in the outer tub 170, a detergent box 130 disposed above the casing 110 for accommodating detergent, and a motor 230 for rotating the inner tub 180.

A balancer 200 for balancing the inner tub 180 is disposed on an upper edge of the inner tub 180. And, a pulsator 220 for providing a rotating water current to washing water is rotatably installed at a bottom surface of the inner tub 180.

There is also provided a suspension 190 having a damper 210 to absorb vibration of the outer tub 170 at the end thereof, for supporting the outer tub 170 so as to be suspended in the casing 110. The motor 230 is installed below the outer tub 170, and provides a rotation force to the inner tub 180 and the washing blade 220. The washing machine further comprises a control panel 261 disposed at an upper front side of the casing 110, and having a controller 260 therein to control the operation of the washing machine 100.

At one side of the casing 110, provided is a water supply valve 160 for supplying cool water or hot water into the inner tub 180 and the outer tub 170 by a control signal from the controller 260. A detergent box housing 135 for accommodating the detergent box 130 is disposed below the water supply valve 160. The water supply valve 160 is supplied with hot water or cool water from a water supply hose 150 connected to the washing machine 100. One or more legs 240 for horizontally mounting the washing machine

100 above the ground are provided at a bottom surface of the casing 110.

An outer tub cover 171 having an approximate ring shape is formed at an upper end of the outer tub 170, thereby covering the balancer 200.

In order to prevent foam occurrence in a dehydration process, the motor 230 is configured so that its rotation speed can be increased step by step in the initial dehydration process. Once the motor 230 reaches a maximum rotation speed or a maximum rpm, the motor 230 is rotated at the maximum rpm for at least five minutes.

The dehydrating method of the washing machine according to the first embodiment of the present invention will be explained.

FIG. 4 is a flowchart showing a dehydrating method of the washing machine of FIG. 3, and FIG. 5 is a graph showing a relation between time and an rpm of a motor in a dehydration process of the washing machine of FIG. 3.

In order to perform a washing process using the washing machine 100, a user opens a door 140, puts laundry into the inner tub 180, and then closes the door 140.

Then, a suitable detergent is put into the detergent box 130 according to the type and amount of laundry introduced into the inner tub 180. Once the washing machine 100 is operated, a washing course, a washing time, a rinsing time, a dehydrating time, a water supply level, etc. are set according to the amount of laundry introduced into the inner tub 180. And, the washing machine 100 is operated according to the set washing method.

That is, water is supplied to the detergent box 130 through the water supply hose 150 and the water supply valve 160. And, the detergent put into the detergent box 130 is supplied to the inner tub 180 with a mixed state with the supplied water.

Once washing water is supplied to the inner tub 180 up to a set level, the inner tub 180 and the washing blade 220 are rotated by the motor 230, thereby performing a washing process. Once the washing process is completed, polluted washing water inside the inner tub 180 is discharged out through a drain pump 251 (refer to FIG. 3) and a drain hose 250 (refer to FIG. 3).

When a plurality of times of the rinsing process is completed, the inner tub 180 and the washing blade 220 are rotated by the motor 230 at a high speed in the same direction. As a result, moisture of laundry is completely centrifugal-dehydrated

The dehydration process may be performed between the washing process and the rinsing process, and may be performed while the rinsing process is repeatedly performed. As shown in FIG. 4, the dehydrating method of the washing machine 100 according to the first embodiment of the present invention comprises: preventing foam occurrence by non-consecutively increasing an rpm of the motor 230 in the initial dehydration process (S100); and when the motor rpm reaches a maximum rpm (RPMmax), maintaining the maximum rpm for a predetermined time (S200).

In the step of preventing foam occurrence (S 100), the rpm of the motor 230 is increased step by step.

As shown in ¹C of FIG. 5, in the initial dehydration process, the rpm of the motor 230 is increased step by step. Here, each rpm has to be maintained for a predetermined time. If each rpm is not maintained for a predetermined time, it may be consecutively increased to cause foam occurrence.

While performing the step of increasing the rpm of the motor 230 step by step (S100), if a resonant rpm exists (S110), the time taken to maintain the resonant rpm is set to be shorter than the time taken to maintain other rpm. Then, a step of maintaining the next larger rpm is performed (S120).

More concretely, once an rpm level of the motor 230 reaches a resonant rpm while the motor 230 has an rpm that increases step by step, time taken to maintain the resonant rpm of the motor 230 has to be shorter than time taken to maintain other rpm. Under a state that the rpm of the motor 230 has reached the resonant rpm, if the time taken to maintain the resonant rpm is not reduced, the washing machine 100 may resonate to cause severe noise and vibration.

The resonant rpm includes a first resonant rpm (R1) due to a horizontal motion of the washing machine 100, and a second resonant rpm (R2) due to a conical motion of the washing machine 100. The washing machine 100 may be modeled according to a mass and a spring. The mass (M) is composed of the inner tub 180, the outer tub 170, the casing 110, etc., and the spring is composed of the suspension 190, etc.

A resonant frequency in the case of modeling horizontal motions of the mass components is a first resonant frequency. When represented as an rpm, the first resonant frequency corresponds to a first resonant rpm (R1 ).

The suspension 190 is implemented to support the outer tub 170 and the inner tub 180 at four points. The outer tub 170 and the inner 180 supported by two pairs of the suspensions 190 symmetrical to each other are vertically moved with a slightly inclined state. That is, the inner tub 180 and the outer tub 170 are moved like a top.

A motion of the inner tub 180 and the outer tub 170 is called as a conical motion. A resonant frequency in the case of modeling the conical motion is a second resonant frequency. When represented as an rpm, the second resonant frequency corresponds to a second resonant rpm (R2).

When the rpm of the motor 230 is not the resonant rpm, time taken to maintain the rpm is not reduced, but is maintained to some degree. Then, a step of maintaining the next rpm is performed (S130).

That is, the rpm of the motor 230 is increased step by step until the number (N) of rpm steps exceeds 10 (S140).

When increasing the rpm of the motor 230 step by step, the number

(N) of the rpm steps is preferably set to be at least 10. As the number (N) of the rpm steps is sufficiently set, foam occurrence is reduced, and dehydrating effects are enhanced. When the number (N) of the rpm steps does not exceed 10, the rpm steps are continuously increased. However, when the number (N) of the rpm steps exceeds 10, the rpm of the motor 230 is consecutively increased (S150).

Preferably, the increasing the rpm of the motor 230 step by step (S 100) is performed until the rpm of the motor 230 reaches about 200 rpm. The reasons are as follows. When the motor 230 is out of a lower rpm region where foam mainly occurs, the motor 230 has to quickly reach a maximum rpm where a maximum dehydration function is implemented, with having its rpm consecutively increased. Since the rpm of the motor 230 where foam occurs in the initial dehydration process is in the range of 120-140 RPM, the rpm of the motor 230 may be consecutively increased when the motor 230 is out of the range.

The rpm of the motor 230 is increased until the motor 230 reaches a maximum rpm (RPMmax) (S160). Once the motor 230 is rotated at the maximum rpm, the maximum rpm is preferably maintained for a sufficient time so as to enhance a dehydration process or a rinsing process (S200).

With consideration of the entire washing time, power consumption, stability of the washing machine, etc., the maximum rpm is maintained for five minutes. That is, the motor 230 is set to rotate for at least five minutes at the maximum rpm (S210).

After water and detergent are sufficiently discharged out as the motor 230 rotates for at least five minutes at the maximum rpm, the dehydration process is ended.

Referring to FIG. 5, in the dehydrating method for the washing machine 100 according to the first embodiment of the present invention, the rpm of the motor is increased step by step in the initial dehydration process. And, when the motor reaches the first resonant rpm (R1 ) and the second resonant rpm (R2), the time taken to maintain the R1 and R2 is reduced to allow the motor to be quickly out of the range (refer to 'C of FIG. 5). Once the motor reaches a maximum rpm, the motor is rotated at the maximum rpm for at least five minutes, thereby enhancing a rinsing performance or a dehydration performance (refer to 'D' of FIG. 5. Here, the maximum rpm (RPMmax) of the motor 230 is preferably about 1000 rpm.

The above-mentioned washing machine is a top loading type one, i.e., a washing machine that a rotation shaft of an inner tub or an outer tub is perpendicular to the ground. However, the washing machine of the present invention may be applied to a front loading type one.

The washing machine and the dehydrating method of the same of the present invention have the following industrial applicability. Since water and detergent remaining on laundry are removed by increasing the rpm of the motor step by step in the initial dehydration process, foam occurrence at a low rpm region is reduced.

It will also be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

1. A dehydrating method of a washing machine comprising: a casing that forms an appearance; an outer tub installed in the casing; an inner tub rotatably installed in the outer tub; and a motor for rotating the inner tub, the method comprising: preventing foam occurrence by non-consecutively increasing an rpm of the motor in an initial dehydration process; and when the rpm of the motor reaches a maximum rpm, maintaining the maximum rpm for a predetermined time.

2. The method of claim 1 , wherein in the step of preventing foam occurrence, the motor rpm is increased step by step.

3. The method of claim 1 or 2, wherein in the step of preventing foam occurrence, the motor rpm is increased by at least ten steps.

4. The method of claim 1 or 2, wherein in the step of preventing foam occurrence, the motor rpm is maintained for a predetermined time, and then is increased step by step into a larger level, and wherein when the motor rpm reaches a resonant rpm, time taken to maintain the resonant rpm is set to be shorter than time taken to maintain other rpm .

5. The method of claim 4, wherein the resonant rpm comprises: a first resonant rpm resulting from a horizontal motion of the washing machine; and a second resonant rpm resulting from a conical motion of the washing machine.

6. The method of claim 3, wherein the motor is rotated at a maximum rpm for at least five minutes.

7. A washing machine, comprising: a casing that forms an appearance; an outer tub installed in the casing; an inner tub rotatably installed in the outer tub; and a motor for rotating the inner tub, wherein an rpm of the motor is increased step by step in an initial dehydration process so as to prevent foam occurrence.

8. The washing machine of claim 7, wherein when the motor rpm reaches a maximum rpm, the motor rotates at the maximum rpm for at least five minutes.