EP1634985A1

EP1634985A1 - Washing machine

Info

Publication number: EP1634985A1
Application number: EP05103537A
Authority: EP
Inventors: Chang Joo Park; Hyun Bae Kim; Chang Hyun Kim
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2004-09-08
Filing date: 2005-04-28
Publication date: 2006-03-15
Also published as: KR20060023067A; US20060048548A1; JP2006075587A

Abstract

A washing machine for minimizing damage to laundry and enabling effective washing of the laundry. The washing machine includes a water tub, a drum and a control unit. The drum is installed in the water tub so as to rotate in a forward and/or a reverse direction. The control unit controls the rotation directions and angles of the rotation of the drum to cause an asymmetric swing motion of the drum.

Description

The present invention relates to a method of controlling a washing machine comprising a water tub to contain water and a drum rotatably installed in the water tub to contain laundry, the method comprising the steps of alternately rotating the drum in opposing first and second directions by predetermined angles so as to create a swing motion of the drum.
A conventional drum type washing machine includes a water tub installed in a machine body to contain wash or rinsing water and a rotatable drum installed in the water tub. A driving force is supplied to the drum by a motor so that the drum can carry out laundry wash and spin-dry cycles. The drum is perforated with a plurality of small holes which allow the wash or rinsing water to flow between the drum and the water tub and in the spin-dry cycle, to centrifugally drain water from laundry, the water discharged into a space between the drum and the water tub through the small holes.
In the drum type washing machine described above, the laundry in the drum is raised by the rotation of the drum along an inner peripheral wall surface of the drum and then dropped from the vicinity of the apex of the drum, so that the laundry is agitated and washed by way of force and friction generated by dropping.
However, the aforementioned manner of washing in a drum type washing machine has a disadvantage that the laundry, specifically silk or wool laundry, is vulnerable to damage by force or friction. In order to eliminate this problem, Japanese Patent Laid-Open Publication Nos. H09-276582 and H09-248395 disclose methods of controlling drum type washing machines which will be explained hereafter.
Japanese Patent Laid-Open No. H09-276582 describes a method of minimizing damage to the laundry by rotating the drum such that it has a swinging manner within a set range so that movement of the laundry is prevented. In this case, however, a two-revolution operation of the drum is added in the course of laundry soak and wash cycles to overturn the laundry, resulting in a limited reduction in laundry damage.
In Japanese Patent Laid-Open No. H09-248395, the wash cycle of the laundry is divided into two portions periods. During a first period, wash water is supplied to the water tub to provide a first water level and the drum is rotated by a first rotation angle, causing the laundry to be dropped and turned. Subsequently, during a second period, wash water is supplied to the water tub to maintain a second water level which is higher than the first level and the drum is rotated by a second angle of rotation smaller than the first angle of rotation. This allows the laundry to be swung whilst completely immersed in the wash water so as to reduce laundry damage. However, in order to sufficiently douse the laundry with the wash water at a low level in the laundry douse cycle, the laundry must be dropped from a high angle of the drum. This may cause damage to the laundry.
Furthermore, although the swing angle of the drum must be kept at 120°C in the wash cycle, such a swing angle is insufficient to turn the laundry and hence prevents complete dousing of the laundry with the wash water and even washing of the laundry. Therefore, this increases wash water usage deteriorating a water saving advantage of the drum type washing machine.
The present invention seeks to provide a drum type washing machine which overcomes or substantially alleviates the problems discussed above and in which the washing machine minimizes damage to laundry during washing and enables effective washing of the laundry.
A drum type washing machine according to the present invention is characterised in that the angle of rotation in the first direction is less than the angle of rotation in the second opposing direction.
Preferably, the difference between the first and second angles of rotation is 15 degrees.
In a preferred embodiment, the angle of rotation of the drum in the first direction is 45 degrees and the angle of rotation in the second direction is 60 degrees.
The motion of the drum may cause the continuous overturn of the laundry in the drum.
A washing machine according to the invention is characterised in that the control unit controls the angle of rotation of the drum such that the angle of rotation in the first direction is less than the angle of rotation in the second direction.
Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a drum type washing machine in accordance with the present invention;
Figure 2 is a block diagram illustrating a control system of the washing machine shown in Figure 1;
Figure 3 is a diagrammatic view illustrating a drum and water tub of the washing machine shown in Figure 1;
Figures 4A and 4B are diagrammatic views illustrating the asymmetric swing motion of the drum;
Figure 5 is a diagrammatic view illustrating the gradual forward rotation of the drum caused by the asymmetric swing motion;
Figure 6 is a graph explaining the concept of the gradual forward rotation of the drum shown in Figure 5; and
Figure 7 is a flow chart illustrating a control method of the washing machine.

Referring to the drawings, there is shown in Figure 1 a drum type washing machine including a water tub 102 to contain wash or rinsing water installed in a machine body 100. A rotatable drum 108 is installed in the water tub 102 and is adapted to carry out laundry wash and spin-dry cycles. A motor 110 supplies a driving force to rotate the drum 108. The peripheral walls of the drum 108 are perforated with a plurality of small holes allowing the wash or rinsing water to flow between the drum 108 and the water tub 102 and, in the spin-dry cycle, water centrifugally drained from laundry to be discharged into a space between the drum 108 and the water tub 102 through the small holes.
In the aforementioned drum type washing machine, when the drum 108 rotates, the laundry in the drum 108 is elevated upwards along an inner circumferential surface of the drum 108 and then dropped from the vicinity of the drum apex (i.e. the highest point) so that the laundry is washed by way of force and friction generated by dropping.
Referring to Figures 1 and 2, the washing machine according to the present invention includes a control unit 202, a water level sensor 204, and an input unit 206. The control unit 202 controls the general operation of the washing machine including douse, wash, rinse, spin-dry and dehydration (drying) of clothes. The water level sensor 204 detects the level of the wash water supplied in the water tub 102 and delivers the detected water level value to the control unit 202. The input unit 206 enables a user to select a desired wash mode and transmits the selected wash mode to the control unit 202.
The drum type washing machine according to the present invention also includes a drive unit 210 to drive the motor 110, a drain pump 116, a dehydration heater 216 and a display device 218. In the wash or rinsing cycle, the motor 110 rotates the drum 108 in forward or reverse directions for specified periods, and in the spin-dry cycle, rotates the drum 108 at a high speed. The drain pump 116 forcibly discharges the wash water from the water tub 102 and the dehydration heater 216 heats air introduced into the water tub 102 causing dehydration (drying) of the laundry using the heated air. The display device 218 indicates the operation state of the washing machine to a user.
In the washing machine described above, if the user selects a swing mode suitable to minimize damage to the laundry, the drum 108 carries out an asymmetric swing motion, rather than a continuous rotating motion, during the laundry douse or wash cycle. As can be seen from Figures 4A and 4B in the swing mode according to the present invention, the forward rotation angle is larger than the reverse rotation angle. For example, the drum 108 rotates in a reverse direction CW by an angle of 45° as shown in Figure 4A and then rotates in a forward direction CCW by an angle of 60° resulting in the net forward rotation of the drum by 15°. This means that due to the difference between the forward and reverse rotation angles as stated above, that by alternately rotating the drum 108 in the forward direction CCW and the reverse direction CW, the net effect is that drum 108 gradually rotates in the forward direction CCW by increments of 15° according to the progress of the swing motion. Consequently, laundry 402 contained in the drum is rotated in the forward direction CCW by increments of 15°.
A diagrammatic view illustrating the gradual forward rotation of the drum 108 caused by the asymmetric swing motion of the washing machine is shown in Figure 5. When the swing mode begins, the drum 108 firstly rotates in the reverse direction CW by a specified angle to set an initial position (as indicated by an arrow O in Figure 5). Then, starting from the initial position, the drum 108 alternately rotates in the forward direction CCW (as indicated by arrows 1, 3 and 5) and in the reverse direction CW (as indicated by arrows 2 and 4) carrying out the asymmetric swing motion. In this case, as a result of the difference between the forward and reverse rotation angles, the drum 108 gradually rotates in the forward direction CCW by an increment of 15° as explained in conjunction with Figures 4A and 4B. That is, the drum 108 simultaneously carries out both a swing motion and a gradual forward rotation.
In the graph shown in Figure 6, the x-axis represents time, and the y-axis represents a velocity command. After the drum 108 is initialised into position by rotating in the reverse direction (as indicated by reference numeral 0), it alternately carries out forward rotations (as indicated by reference numerals 1, 3 and 5) and reverse rotations (as indicated by reference numerals 2 and 4). Although the velocity commands (amplitudes) of the forward and reverse rotations are the same as each other, the forward rotation angle is larger than the reverse rotation angle since the forward rotation time is longer than the reverse rotation time. Therefore, it will be appreciated that, even though the drum 108 continuously swings in the swing mode, the average of such forward and reverse rotations, indicated by a dashed-line 602, is biased in the forward direction CCW. This means that the drum 108 has a net forward rotation across the entire swing mode.
As shown in Figure 7, the desired wash mode is initially set (operation 702). In this case, it is determined whether the wash mode selected by the user is the swing mode suitable to protect the laundry from excessive shock and friction generated by the rotation of the drum or not (operation 704). If not, the corresponding wash mode is carried out (operation 706).
If the swing mode is selected, the drum initially rotates in the reverse direction by the specified angle and subsequently the drum is controlled in a rotational direction such that it alternately rotates in forward and reverse direction by the specified forward and reverse rotation angles (operation 708). After the lapse of a predetermined time, the swing mode ends (operation 710).
As is apparent from the above description, the present invention seeks to provide a drum type washing machine which can minimize damage to laundry, specifically silk, or wool laundry vulnerable to shock or friction caused during washing, by carrying out an asymmetric swing motion of a drum thereof. Further, according to the aforementioned embodiment of the present invention, since the drum simultaneously swings and gradually rotates forward, laundry can be easily overturned even by rotation of the drum across a small angle, resulting in a reduction of douse or wash time and enabling effective washing of the laundry. The gradual forward rotation, furthermore, enables continuous overturn of the laundry.
Although an embodiment of the invention has been shown and described, it will be appreciated by those skilled in the art that changes may be made to this embodiment without departing from the principles of the invention, the scope of which is defined by the claims and their equivalents and the foregoing description should be regarded as a description of a preferred embodiment only.

Claims

A method of controlling a washing machine comprising a rotatably mounted drum to receive laundry, the method comprising the steps of alternately rotating the drum through a predetermined angle in opposing first and second directions to create a swinging motion of the drum, characterised by the step of rotating the drum through a greater predetermined angle in the first direction than in the second direction.
A method of controlling a washing machine according to claim 1, including the step of rotating the drum in the first direction by an angle which is 15 degrees greater than the angle of rotation in the second direction.
A method of controlling a washing machine according to claim 2, including the step of rotating the drum through an angle of 60 degrees in the first direction and 45 degrees in the second direction.
A method of controlling a washing machine according to any preceding claim wherein the washing machine includes control means to enable one of a plurality of wash modes to be selected, only some of which include a swing cycle that causes the drum to rotate through a greater predetermined in the first direction than in the second direction, the method including the step of determining whether a wash mode including a swing cycle has been selected and performing said selected wash mode accordingly.
A method of controlling a washing machine according to any preceding claim including the step of performing a default wash mode if a wash mode without a swing cycle is selected.
A washing machine comprising a rotatably mounted drum to receive laundry and a control unit to control rotation of the drum through predetermined angles in opposing first and second directions, to create a swing motion of the drum, characterised in that the control unit controls the angle of rotation of the drum such that it rotates through a greater predetermined angle in the first direction than in the second direction.
A washing machine comprising a water tub, a drum in the water tub, the drum being rotatable in a forward rotation direction at a forward rotation angle and a reverse rotation direction opposite of the forward direction at a reverse rotation angle, and a control unit adapted to control the rotation directions and angles to yield asymmetric swing motion of the drum.
The machine according to claim 7 wherein the control unit controls the rotation angles so that the forward angle of the drum is greater than the reverse angle of the drum during the asymmetric swing motion.
A washing machine comprising a water tub, a drum in the water tub, the drum being rotatable in a forward direction and a reverse rotation direction opposite of the forward direction and a control unit adapted to control the rotation of the drum to yield an asymmetric swing motion of the drum, wherein during the asymmetric swing motion, the control unit controls forward and reverse rotation angles so that a reference position of the drum is displaced in the forward rotation direction.
The machine according to claim 9 wherein the control unit controls the rotation angles so that the forward angle is greater than the reverse rotation angle to cause gradual displacement of the reference position.
A washing machine control method comprising determining whether a set wash mode is an asymmetrical swing mode in which a drum is alternately rotated in a forward direction and a reverse direction by respective forward and reverse angles, asymmetrically swinging the drum when the set wash mode is the asymmetrical swing mode, so that the drum alternately rotates in the forward direction and the reverse direction by the respective forward and reverse rotation angles, the alternately rotating causing one of a net forward rotation of the drum and a net reverse rotation of the drum.
The washing machine control method of claim 11 wherein the forward rotation angle is 60° and the reverse rotation angle is 45°.
The washing machine control method of claim 11 wherein a difference between the forward and the reverse rotation angles is 15°.
The washing machine control method of claim 11 wherein the one of the rotation angles is greater than the other of the angles.
The washing machine control method of claim 11 wherein the alternately rotating yields continuous overturn of laundry in the drum.