CN112654742A

CN112654742A - Washing machine and control method thereof

Info

Publication number: CN112654742A
Application number: CN201980056555.9A
Authority: CN
Inventors: 金宰铉; 金城均; 林明训; 金佳妍; 李顶勋; 郑还镇; 禹景喆
Original assignee: LG Electronics Inc
Current assignee: LG Electronics Inc
Priority date: 2018-08-30
Filing date: 2019-08-21
Publication date: 2021-04-13
Also published as: WO2020045888A1; JP2021534897A; EP3845696A1; EP3845696A4; AU2019329626A1; US20210355622A1

Abstract

The present invention relates to a washing machine formed such that a cylindrical drum formed by processing a metal sheet is rotated about a horizontal axis, wherein the washing machine includes a plurality of protrusion portions extending in a longitudinal direction and spaced in a circumferential direction on an inner circumferential surface of the drum, and the protrusion portions protrude toward an inside of the drum by a height of 2.0% to 6.0% of a diameter of the drum.

Description

Washing machine and control method thereof

Technical Field

The present disclosure relates to a washing machine having a drum rotating about a horizontal axis, and more particularly, to a washing machine having a height of a protrusion structure formed on an inner circumferential surface of the drum less than 40 mm.

Background

Washing machines configured with a drum carrying laundry, rotating about a horizontal axis, are well known. For example, in the washing machine disclosed in korean patent application No. 10-2011-0022359, the lifter disposed in the inner circumferential surface of the drum lifts the laundry when the drum rotates.

In such a washing machine provided with a lifter installed in the drum, the laundry is lifted up to a certain height by a physical force applied by the lifter and then dropped, or friction is caused between the lifter and the laundry. Therefore, it is possible to secure a certain degree of washing force, which is less affected by the amount of water filled in the drum, the amount of laundry (amount of laundry), and the rotation speed (RPM) of the drum, compared to the structure without the lifter.

Meanwhile, in the case of the drum without the lifter, the centrifugal force generated by the rotation of the drum becomes a driving force to lift the laundry. In this case, when the rotation speed of the drum is equal to or higher than a laundry attachment speed at which a centrifugal force exerted on the laundry is equal to gravity, the laundry is rotated while being attached to the inner circumferential surface of the drum. Although the diameter of the drum varies, the laundry attachment speed is 90rpm to 110 rpm.

Meanwhile, when the lifter is installed in the drum, not only the centrifugal force but also more force of the lifter lifting the laundry is applied. Therefore, even if the rotation speed of the drum is lower than 90rpm, the laundry may be rotated while being adhered to the drum. In a conventional washing machine, a lifter of about 40mm in height is applied. In this case, when the rotation speed of the drum reaches about 55rpm, the laundry is rotated while being adhered to the drum.

That is, such a conventional washing machine must limit the rotation speed of the drum to about 55rpm or less so that the laundry is lifted by the lifter and then dropped. However, there are various factors that affect the washing power. For example, various factors include friction between the drum and the laundry, impact force applied to the laundry by the lifter, bending and stretching of the laundry, and dropping of the laundry by the lifter. In particular, since these factors are closely related to the rotation speed of the drum, it is required to design a method that can rotate the drum at a higher speed than the conventional drum while dropping the laundry.

Disclosure of Invention

Technical problem

The present disclosure is made in view of the above problems, and provides a washing machine that increases an upper limit of a drum rotation speed, which may cause laundry to fall due to rotation of a drum, and cause the laundry to flow, compared to the related art.

The present disclosure also provides a washing machine that forms protrusions for lifting laundry on an inner circumferential surface of a drum, and appropriately designs the height of the protrusions so that the laundry may flow in the drum without adhering to the drum even if the rotation speed of the drum is 60rpm or more.

Technical scheme

The present disclosure relates to a washing machine configured to have a drum for loading laundry and rotating about a horizontal axis. A plurality of protrusions are provided on an inner circumferential surface of the drum. The protrusions extend in the front-rear direction, and the plurality of protrusions are spaced in the circumferential direction.

The protrusions protrude inwardly into the drum to a height of 2.0% to 6.0% of the diameter of the drum. Alternatively, the height at which the protrusions protrude inwardly into the drum is 10mm to 30 mm.

On the inner peripheral surface of the drum, there is no projection structure higher than any of the plurality of projections between a pair of adjacent projections arbitrarily selected from among the plurality of projections.

The drum further includes a plurality of bosses located on the inner peripheral surface, formed to be lower than any one of the plurality of protrusions, and on the inner peripheral surface of the drum, there is no protrusion structure other than at least one of the plurality of bosses between a pair of adjacent protrusions arbitrarily selected from among the plurality of protrusions. The height of the bosses is less than 5 mm.

Between a pair of adjacent protrusions arbitrarily selected from the plurality of protrusions, there is no protrusion structure on the inner circumferential surface of the drum, or there is only at least one of the plurality of embossments.

The protrusion includes: a first side surface portion forming a positive first angle with respect to the inner circumferential surface at a first point on the inner circumferential surface of the drum when viewed from the front; and a second side surface portion that forms a negative second angle with respect to the inner peripheral surface at a second point on the inner peripheral surface that is circumferentially spaced from the first point when viewed from the front. At least one of the first angle and the second angle is 17.5 degrees or less.

The length from the front end to the rear end of the protrusion is 50% to 100% of the length of the drum. The drum has a front end belt portion and a rear end belt portion which are flat and formed in a front end and a rear end, respectively, and the projection is disposed between the front end belt portion and the rear end belt portion.

The protrusion is integrally formed with the drum. The drum is manufactured by processing a metal sheet made of stainless steel, and has a thickness of 0.4mm to 0.6 mm.

Alternatively, the protrusion is made of synthetic resin and coupled with the drum.

The drum may have a diameter of 484mm, and the height of the protrusion protruding toward the inside of the drum may be 10.0mm to 30.0 mm.

The diameter of the drum may be 515mm, and the height of the protrusion protruding toward the inside of the drum may be 10.6mm to 30.9 mm.

The diameter of the drum may be 575mm, and the height of the protrusion protruding toward the inside of the drum may be 11.8mm to 34.5 mm.

The diameter of the drum may be 590mm, and the height of the protrusion protruding toward the inside of the drum may be 12.1mm to 35.4 mm.

A control method of a washing machine of the present disclosure controls a drum to continuously rotate one or more turns in one direction at a set speed between 60rpm and 90rpm so that laundry is raised to a certain height by a protrusion and then dropped at least once.

Advantageous effects

According to the washing machine of the present disclosure, even if the drum is rotated at a higher speed than the related art, laundry is not adhered to the drum but may flow in the drum, thereby improving washing power.

In particular, even if the rotation speed of the drum is 60rpm or more, the laundry does not adhere to the drum but flows in the drum, thereby increasing the laundry adhesion speed by about 18% compared to the related art.

In addition, since the laundry flows inside the drum even though the drum rotates at a higher speed than the related art, a frictional force between the laundry and the drum is increased, thereby enhancing a frictional effect.

Drawings

Fig. 1 is a side cross-sectional view of a washing machine according to one embodiment of the present disclosure;

fig. 2 schematically illustrates a cross-section of the washing outer tub shown in fig. 1;

fig. 3 schematically illustrates a longitudinal section of the washing outer tub shown in fig. 1;

FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 3;

FIG. 5 is a graph showing a clothes attachment speed according to a protrusion height;

FIG. 6 is a graph for explaining the correlation between the protrusion height and the side surface angle; and

fig. 7 illustrates the flow of laundry according to the rotation speed of the drum.

Detailed Description

Advantages and features of the present disclosure and methods of accomplishing the same will become apparent from the following detailed description of embodiments with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The present disclosure is to be limited only by the scope of the following claims. Like reference numerals refer to like elements throughout the specification.

Referring to fig. 1, a washing machine according to an embodiment of the present disclosure may include: a housing 1 forming an outer shape; a water storage tank 3 disposed in the housing 1 and storing washing water; a washing tub 4 rotatably installed in the water storage tank 3 and loaded with laundry; and a motor 9 for rotating the washing tub 4.

The washing tub 4 includes: a front cover 41 having an opening for the entrance and exit of laundry; a cylindrical drum 42 arranged substantially horizontally such that a front end is coupled to the front cover 41; and a rear cover 43 coupled to a rear end of the drum 42. The rotation shaft of the motor 9 may be connected to the rear cover 43 by passing through the rear wall of the water storage tank 3. A through hole 42h may be formed in the drum 42 so that water may be exchanged between the washing tub 4 and the water storage tank 3.

The washing tub 4 rotates about a horizontal axis. Here, "horizontal" does not mean a geometric horizontal in a strict sense, even if the washing tub 4 is inclined at an angle with respect to the horizontal (as shown in fig. 1), which is closer to the horizontal than to the vertical. Therefore, it can be said that the washing tub 4 rotates about a horizontal axis.

In addition, the washing tub 4 includes a plurality of protrusions 20 provided on an inner circumferential surface of the drum 42. A plurality of projections 20 extend in the front-rear direction on the inner circumferential surface of the drum 42, and these projections 20 are spaced apart in the circumferential direction, preferably, arranged at a constant angle (equal angle) with respect to the center O of the drum 42.

There is no protrusion structure higher than any of the plurality of protrusions 20 between a pair of adjacent protrusions 20 arbitrarily (or randomly) selected from among the plurality of protrusions 20.

In other words, a pair of adjacent protrusions 20 is adopted anyway, and there is no protrusion structure between them that protrudes higher than the protrusions 20.

A plurality of bosses 425 may be provided on the inner circumferential surface of the drum 42. The bosses 425 have a protruding structure formed on the inner circumferential surface, and protrude into the drum 42 at a height lower than any one of the plurality of protrusions 20.

On the inner peripheral surface of the drum 42, there is no protrusion structure other than at least one of the plurality of bosses 425 between a pair of adjacent protrusions arbitrarily selected from among the plurality of protrusions 20.

The embossments 425 may be formed integrally with the drum 42, and the size and/or height of the plurality of embossments 425 need not be constant, as shown in fig. 3, a plurality of embossments 425 may be formed with a size gradually increasing or decreasing in the longitudinal direction of the drum 42.

The height of the bosses 425 is 5mm or less.

Meanwhile, the drum 42 is manufactured by processing a metal sheet made of stainless steel, and may have a thickness of 0.4mm to 0.6 mm. The cylindrical drum 42 may be formed by rounding a rectangular metal sheet and bonding (e.g., welding) both ends to each other. The metal sheets are preferably, but not necessarily limited to, the STS430 series.

A laundry loading port is formed in a front surface of the casing 1, and a door 2 for opening and closing the laundry loading port is rotatably provided in the casing 1. Inside the housing 1, a water supply valve 5, a water supply pipe 6, and a water supply hose 8 may be installed. When the water supply valve 5 is opened to supply water, the washing water passing through the water supply pipe 6 may be mixed with the detergent in the dispenser 14 and then supplied to the water storage tank 3 through the water supply hose 8.

An input port of the pump 11 is connected to the water storage tank 3 via a discharge hose 10, and a discharge port of the pump 11 is connected to a drain pipe 12. The water discharged from the water storage tank 3 via the discharge hose 10 is pumped by the pump 11 and flows along the discharge pipe 12, and then discharged to the outside of the washing machine.

Fig. 7 illustrates the flow of laundry according to the rotation speed of the drum. Referring to fig. 7, during the rotation of the drum 42, the force acting on the laundry introduced into the drum 42 may be a centrifugal force Fc generated by the rotation of the drum 42, a gravity Fg, and a lifting force Fn applied by the protrusion 20.

As shown in (a) of fig. 7, since the centrifugal force Fc is relatively small when the drum 42 is rotated at a low speed, the laundry is lifted to a certain height by the protrusion 20, and then the laundry is separated from the protrusion 20 and falls down when the sum of the centrifugal force Fc and the lifting force Fn cannot bear the weight Fg. Such a laundry flow is defined as a rolling motion.

Fig. 7 (b) shows a state in which the rotation speed of the drum 42 is higher than that of fig. 7 (a), and shows that the laundry is dropped after being lifted to a higher position. In particular, the rotation angle of the position where the laundry is dropped from the lowest point of the drum is equal to or greater than 90 degrees, and such laundry flow is defined as a tumbling motion.

If the rotation speed of the drum 42 is further increased, as shown in (c) of fig. 7, the laundry does not fall even at the highest point of the drum 42, but rotates while being attached to the drum 42. The lowest value of the rotation speed of the drum 42, which may cause laundry to adhere in the form as in (c) of fig. 7, is defined as a laundry adhesion speed Vf.

When the drum 42 has no protrusion 20, the lifting force Fn is removed, and thus, only the centrifugal force Fc and the gravity Fg remain as the force acting on the laundry. In this case, the laundry attachment speed vf can be obtained from a balance equation in which the centrifugal force is equal to the gravity. Since the mass of the laundry is cancelled out on both sides of the balance equation, the laundry adhesion speed vf becomes a value that depends on the drum diameter, is independent of the laundry mass, and is a preset value that can be obtained by knowing the drum diameter.

Meanwhile, when the protrusion 20 is formed in the drum 42, the lifting force Fn acts more, and thus, the laundry attachment speed vf becomes lower compared to the case where the protrusion 20 is not applied. At this time, the laundry attachment speed vf will vary according to the structure of the protrusion 20. However, in the conventional washing machine in which the drum 42 has a diameter of 24 to 27 inches and the lifter (protrusion) has a height of 40mm or more, the laundry attachment speed vf is about 55rpm or less.

The washing force is determined by several factors such as deflection, friction, and falling of the laundry. These factors are closely related to the rotation speed of the drum 42, and in particular, may cause the laundry to fall or a relative motion (or a flow in the drum) with respect to the drum, such as a rolling or tumbling motion, but at this time, the higher rotation speed of the drum 42 is advantageous to enhance the washing force.

In this regard, it is necessary to design a method of increasing the laundry adhesion speed vf while rotating the drum 42 at a higher speed than the related art, and the present disclosure reduces the height h of the protrusion 20 (i.e., the height protruding into the drum 42) to reduce the lifting force Fn as compared with the related art. At this time, the height h of the protrusion 20 is 2.0% to 6.0% of the diameter D compared to the diameter D of the drum 42, and the absolute value is about 10mm to 30 mm.

The control method of the washing machine according to one embodiment of the present disclosure may realize a rolling or tumbling motion while rotating the drum 42 at a higher speed than the related art.

Specifically, when the protrusion height of the protrusions 20 is 2.0% to 6.0% of the diameter of the drum 42, the drum 42 is continuously rotated one or more turns in one direction at a speed set between 60rpm and 90 rpm. Accordingly, the operation in which the laundry in the drum 42 is raised to a certain height by the protrusion 20 and then dropped may be performed at least once.

The set speed may be a speed that causes a rolling motion, in which case the laundry in the drum 42 rises from the lowest point of the drum 42 to an angle below 90 degrees in the rotation direction of the drum 42 and then falls.

Alternatively, the set speed may be a speed that causes a tumbling motion. At this time, the laundry in the drum 42 rises from the lowest point of the drum 42 to an angle of 90 degrees or more and 180 degrees or less in the rotation direction of the drum 42, and then falls.

A controller (not shown) for controlling the rotation of the motor 9 may be provided, and the drum 42 may be rotated by the controller controlling the speed of the motor 9.

Fig. 2 schematically illustrates a cross-section of the washing outer tub shown in fig. 1, fig. 3 schematically illustrates a longitudinal section of the washing outer tub shown in fig. 1, and fig. 4 is a cross-sectional view taken along line IV-IV of fig. 3. Hereinafter, this will be described with reference to fig. 2 to 4.

The length of the protrusion 20 in the longitudinal direction (or front-rear direction) of the drum 42 is longer than the width of the drum 42 in the circumferential direction when viewed from the front of the drum 42. These protrusions 20 are symmetrically arranged with respect to the center of the drum 42, and in the present embodiment, three protrusions 20 are arranged at an equiaxed angle of 120 degrees with respect to the center of the drum 42, but not necessarily limited thereto.

The protrusion 20 may be integrally formed with the drum 42. For example, the protrusion 20 may be formed by plastic working a metal sheet. However, the present disclosure is not limited thereto, and in some embodiments, the protrusion 20 may be formed separately from the drum 42 and then coupled to the drum 42. In particular, in the latter case, the protrusion 20 may be made of synthetic resin.

Meanwhile, in order to smoothly lift the laundry by expanding the contact area between the protrusion 20 and the laundry (or the area where the protrusion 20 applies the lifting force Fn), the length of the protrusion 20 should be appropriate, and in this regard, the present disclosure suggests that the length L1 from the front end to the rear end of the protrusion 20 is 50% to 100% of the length L0 of the drum 42. In particular, even if the length L1 of the protrusion 20 is close to 50% of the length L0 of the drum 42, the protrusion 20 is preferably provided such that the front end of the protrusion 20 is located at a position spaced rearward from the front end of the drum 42, so that the protrusion 20 can be arranged to cover the front and rear of the drum 42.

Specifically, the drum 42 has a front end belt portion 42a and a rear end belt portion 42b which are flat and formed at the front end and the rear end, respectively, and the projection 20 may be disposed between the front end belt portion 42a and the rear end belt portion 42 b.

Meanwhile, referring to fig. 4, when viewed from the front, the protrusion 20 may include: a first side surface portion 21 forming a positive first angle + θ with respect to the inner peripheral surface at a first point P1 on the inner peripheral surface of the drum 42; and a second side surface portion 22 forming a negative second angle-theta with respect to the inner peripheral surface at a second point P2 circumferentially spaced from the first point P1 on the inner peripheral surface. Here, at least one of the first angle and the second angle is 17.5 degrees or less. Hereinafter, the angle θ is defined as a side surface angle.

In the present embodiment, the first side surface part 21 and the second side surface part 22 are symmetrical, and the first angle and the second angle have the same size, but are not necessarily limited thereto.

Fig. 5 is a graph showing the laundry attachment speed vf according to the protrusion height. Fig. 6 is a graph for explaining the correlation between the protrusion height and the side surface angle. First, as described above, fig. 5 shows that the laundry attachment speed vf becomes lower as the height h of the protrusion 20 becomes higher. Meanwhile, when the height h of the protrusions 20 is 5mm or less, the washing performance seems to be good as the laundry attachment speed vf becomes high, but this is not the case.

When the height h of the protrusion 20 is 5mm or less, since the lifting force Fn of the protrusion 20 is too small, the laundry rolls almost at the home position in a state of not reaching the laundry attachment speed vf of the drum 42, or moves up and down only within a very small rotation angle, and then suddenly starts to be attached to the drum 42 when reaching the laundry attachment speed vf. As the amount of laundry becomes smaller, this type of laundry flow is increased and dropping or deflection of the laundry may not be smoothly caused, so that washing power is deteriorated. For this purpose, the height h of the protrusions 20 should be greater than at least 5mm, preferably at least 10mm or more.

The height h of the protrusions 20 is preferably 30mm or less, in which case the laundry attachment speed vf is about 65rpm or more, so that the laundry attachment speed can be expected to increase by about 18% as compared with 55rpm at the conventional height of 40 mm.

Preferred values of the lower limit LSL and the upper limit USL of the height h of the protrusion 20 for each diameter D of the drum 42 are as follows. Here, the diameter of the drum 42 may be any one of an inner diameter, an outer diameter, and an intermediate value between the inner diameter and the outer diameter of the drum 42.

[ Table 1]

Diameter of roller (D (mm))	LSL(mm)	USL(mm)
			484	10.0	30.0
515	10.6	30.9
			575	11.8	34.5
590	12.1	35.4

Meanwhile, referring to fig. 6, it can be seen that the tumbling or tumbling of the laundry cannot be caused in the region a where the height h of the protrusion 20 is less than 5mm and the side surface angle θ is less than 17.5 degrees. Therefore, even if the height h of the protrusion 20 is 5mm, the side surface angle θ is preferably at least 17.5mm to cause rolling or tumbling.

The region B shown in fig. 6 indicates a region where the height h of the protrusion 20 is 5mm or more and the side surface angle θ is 17.5 or more, and in which the rolling or tumbling motion of the laundry may be induced. However, the height of the protrusions 20, which can further enhance the washing performance due to such movement, is preferably 10mm or more.

Meanwhile, the curves shown by the broken lines in fig. 6 connect the thresholds of the side surface angle θ that can cause rolling or tumbling.

Meanwhile, the control method of the washing machine according to one embodiment of the present disclosure may also be implemented as processor-readable code on a processor-readable recording medium. The processor-readable recording medium includes various recording devices that store data that can be read by a processor. Examples of the processor-readable recording medium are ROM, RAM, CD-ROM, magnetic tapes, floppy disks, optical data storage devices, and include those implemented in the form of carrier waves, such as data transmission through the internet. In addition, the processor-readable recording medium is dispersed in computer systems connected through a network, and codes read by the processor may be stored and executed in a distributed manner.

Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the scope of the principles of this disclosure. More specifically, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.

Claims

1. A washing machine configured to have a drum for loading laundry and rotating about a horizontal axis, the washing machine comprising:

a plurality of protrusions extending in a front-rear direction on an inner circumferential surface of the drum and spaced apart in a circumferential direction,

wherein the protrusion protrudes inward into the drum by a height of 2.0% to 6.0% of the diameter of the drum, and

2. The washing machine as claimed in claim 1, wherein the drum further comprises a plurality of bosses on the inner circumferential surface formed lower than any one of the plurality of protrusions, and

wherein, on the inner peripheral surface of the drum, there is no protrusion structure other than at least one of the plurality of bosses between a pair of adjacent protrusions arbitrarily selected from among the plurality of protrusions.

3. The washing machine as claimed in claim 2, wherein the height of the bosses is 5mm or less.

4. The washing machine as claimed in claim 1, wherein the protrusion comprises:

a first side surface portion forming a positive first angle with respect to the inner circumferential surface at a first point on the inner circumferential surface of the drum when viewed from the front; and

a second side surface portion that forms a negative second angle with respect to the inner peripheral surface at a second point on the inner peripheral surface that is circumferentially spaced from the first point when viewed from the front,

wherein at least one of the first angle and the second angle is 17.5 degrees or less.

5. The washing machine as claimed in claim 1, wherein a length from a front end to a rear end of the protrusion is 50% to 100% of a length of the drum.

6. The washing machine as claimed in claim 5, wherein the drum has a front end belt portion and a rear end belt portion which are flat and formed in front and rear ends, respectively,

wherein the protrusion is disposed between the front end band portion and the rear end band portion.

7. The washing machine as claimed in claim 1, wherein the protrusion is integrally formed with the drum.

8. The washing machine as claimed in claim 7, wherein the drum is manufactured by processing a metal sheet made of stainless steel, and has a thickness of 0.4mm to 0.6 mm.

9. The washing machine as claimed in claim 1, wherein the drum is formed of stainless steel, and

the protrusion is made of synthetic resin and coupled with the drum.

10. The washing machine as claimed in claim 1, wherein the protrusion protrudes inward into the drum by a height of 10mm to 30 mm.

11. A control method of a washing machine configured to have a drum for loading laundry and rotating about a horizontal axis, the washing machine configured to have a plurality of protrusions extending in a front-rear direction on an inner circumferential surface of the drum and spaced in a circumferential direction, and protruding inward into the drum to a height of 2.0% to 6.0% of a diameter of the drum, the control method comprising controlling the drum to continuously rotate in one direction for one or more turns at a set speed of between 60rpm and 90rpm such that the laundry is raised to a certain height by the protrusions at least once and then falls.

12. The control method according to claim 11, wherein the set speed is set such that the laundry in the drum rises to an angle of 90 degrees or less in a rotation direction of the drum from a lowest point of the drum and then falls.

13. The control method according to claim 11, wherein the set speed is set such that laundry in the drum rises to an angle of 90 degrees or more and 180 degrees or less in a rotation direction of the drum from a lowest point of the drum and then falls.