US20040139558A1

US20040139558A1 - Method for controlling dehydration speed of washing machine

Info

Publication number: US20040139558A1
Application number: US10/755,472
Authority: US
Inventors: Joon-Woo Kim; Young-Ho Kim; Dong-won Kim; Byoung-Wook Min
Original assignee: LG Electronics Inc
Current assignee: LG Electronics Inc
Priority date: 2003-01-15
Filing date: 2004-01-13
Publication date: 2004-07-22
Also published as: ATE426700T1; RU2004101232A; CN1517475A; EP1441055A1; KR20040065668A; DE602004020132D1; EP1441055B1; RU2262563C1; KR100504866B1

Abstract

The present invention discloses a method for controlling a dehydration speed of a washing machine which can reduce vibrations and noises of the washing machine. The method for controlling the dehydration speed of the washing machine includes the steps of: setting the dehydration speed on the basis of an amount of laundry put into the washing machine; and controlling a rotation speed of a motor of the washing machine on the basis of the set dehydration speed.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a washing machine, and more particularly, to a method for controlling a dehydration speed of a washing machine.

2. Description of the Background Art

In general, when detergent, water and laundry are put into a washing machine, especially a drum washing type washing machine, the washing machine washes the laundry by using a frictional force between a drum rotated by a driving force of a built-in motor and the laundry. In the drum washing type washing machine, the laundry is rarely damaged and tangled, and washing effects are improved as if the laundry was beaten and rubbed.

The structure of the conventional drum washing machine will now be explained with reference to FIG. 1.

FIG. 1 is a cross-sectional diagram illustrating the conventional drum washing machine.

Referring to FIG. 1, the drum washing machine includes a

tub

3 installed inside a cabinet 5, a drum 9 installed inside the tub 3, a drum shaft 13 directly coupled to the drum 9, for transmitting a driving force of a motor 6 to the drum 9, bearings 12 installed in the front and rear sides of the drum shaft 13, a bearing housing (not shown) installed in the center of the rear wall of the tub 3, for supporting the bearings 12, a stator 7 installed on the rear wall of the tub 3, for forming the motor 6, a rotor 8 installed on the drum shaft 13, for forming the motor 6 with the stator 7, a door 1 installed in the front side of the cabinet 5, a gasket 2 installed between the door 1 and the tub 3, a hanging spring 4 installed between the inside of the top surface of the cabinet 5 and the upper side of the outer circumference of the tub 3, for supporting the tub 3, a friction damper 10 installed between the inside of the bottom surface of the cabinet 5 and the lower side of the outer circumference of the tub 3, for damping vibrations of the tub 3 during the dehydration, and a motor sensor 11 installed in one side of the motor 6, for sensing a rotation speed of the rotor 8. Here, the rotation speed of the rotor 8 implies the rotation speed of the motor 6.

A conventional method for controlling a dehydration speed of a drum washing machine will now be described.

When a mode of the washing machine is changed into a dehydration mode and the

rotor

8 is rotated, the motor sensor 11 continuously senses the rotation speed of the rotor 8, and outputs the sensed speed to a controller (not shown).

The controller compares the rotation speed of the

rotor

8 sensed by the motor sensor 11 with a preset rotation speed, and controls the rotation speed of the rotor 8 according to a dehydration speed suitable for the dehydration mode selected by the user.

The dehydration mode will now be explained in more detail.

The laundry is washed in a washing rotation speed (for example, about 45 rpm to 50 rpm(rpm: Revolution Per Minute)). To dehydrate the washed laundry, the rotation speed of the

drum

9 connected to the rotor 8 is increased to about 100 rpm by increasing the rotation speed of the rotor 8. The laundry is dehydrated in the rotation speed. That is, the controller (not shown) dehydrates the laundry by increasing the rotation speed of the rotor 8 to the dehydration speed set by the user (800 rpm or 1400 rpm).

However, the conventional washing machine includes a brushless direct current (BLDC) motor for converting the dehydration speed according to a kind of cloth or upon the user's request, which increases vibrations and noises. For example, if the rotation speed of the motor is controlled in the preset dehydration speed, regardless of a kind and amount of laundry put into the washing machine, even when the laundry is small, the motor is operated in the preset dehydration speed, thereby increasing vibrations and noises of the washing machine.

In addition, the conventional washing machine has the BLDC motor for converting the dehydration speed according to a kind of cloth or upon the user's request, which increases manufacturing expenses.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide a method for controlling a dehydration speed of a washing machine which can reduce vibrations and noises of the washing machine.

Another object of the present invention is to provide a method for controlling a dehydration speed of a washing machine which can reduce vibrations and noises of the washing machine, by setting the dehydration speed on the basis of an amount of laundry put into the washing machine, and controlling a rotation speed of a motor according to the set dehydration speed.

Yet another object of the present invention is to provide a method for controlling a dehydration speed of a washing machine which can reduce vibrations and noises of the washing machine, by changing a number of poles of a motor of the washing machine, and controlling a voltage applied to the motor when the number of the poles is changed.

Yet another object of the present invention is to provide a method for controlling a dehydration speed of a drum washing machine which can reduce vibrations and noises of the drum washing machine and cut down manufacturing expenses of the drum washing machine, by changing a number of poles of an induction motor of the drum washing machine, and controlling a voltage applied to the induction motor when the number of the poles is changed.

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 method for controlling a dehydration speed of a drum washing machine, including the steps of: setting the dehydration speed on the basis of an amount of laundry put into the washing machine; and controlling a rotation speed of a motor of the washing machine on the basis of the set dehydration speed.

The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. [0021]
In the drawings: [0022]
FIG. 1 is a vertical-sectional diagram illustrating a conventional drum washing machine; [0023]
FIG. 2 is a flowchart showing a method for controlling a dehydration speed of a drum washing machine in accordance with the present invention; [0024]
FIG. 3 is an exemplary diagram illustrating conversion of a number of poles of a stator of a motor of the drum washing machine in accordance with the present invention; and [0025]
FIG. 4 is a graph showing torque-speed curves of the motor in the method for controlling the dehydration speed of the drum washing machine in accordance with the present invention.[0026]

DETAILED DESCRIPTION OF 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. [0027]
A method for controlling a dehydration speed of a washing machine which can reduce vibrations and noises of the washing machine by changing a number of poles of a motor of the washing machine, and controlling a voltage applied to the motor when the number of the poles is changed will now be described in detail with reference to FIGS. [0028] 2 to 4.
FIG. 2 is a flowchart showing the method for controlling the dehydration speed of the drum washing machine in accordance with the present invention. [0029]
As illustrated in FIG. 2, the method for controlling the dehydration speed of the drum washing machine includes the steps of: inputting a preset dehydration speed by the user (S[0030] 11); confirming the range of the input dehydration speed (S12); changing a number of poles of an induction motor installed in the drum washing machine according to the range of the dehydration speed (S13 and S17); converting the dehydration speed by controlling a phase of a voltage inputted to the induction motor installed in the drum washing machine, when the number of the poles of the motor is changed (S14 and S18); calculating the dehydration speed converted by changing the number of the poles of the motor and controlling the phase, and a torque and efficiency of the induction motor (S15 and S19); and evaluating performance satisfaction of the induction motor on the basis of the torque and efficiency of the induction motor (S16 and S20).
The operation of the method for controlling the dehydration speed of the drum washing machine in accordance with the present invention will now be described in more detail. [0031]
The user inputs the preset dehydration speed according to a dehydration course (S[0032] 11). Here, when the user puts the laundry into the drum washing machine, a hall sensor (not shown) installed inside the drum washing machine senses a kind and amount of the laundry on the basis of the rotation speed of the motor, and sets the dehydration speed according to the kind and amount of the laundry (S12). The amount of the laundry can be sensed on the basis of the rotation speed of the motor measured when the motor is rotated in the preset rotation speed.
Thereafter, the range of the dehydration speed inputted by the user is confirmed. When the input dehydration speed is 800 rpm, the number of the poles of the motor is changed into 8, and then the motor is operated. That is, when the motor has 8 poles, the rotation speed of the motor is 800 rpm. Here, the rotation speed of the motor can be controlled between 400 rpm and 800 rpm by controlling the voltage applied to the motor by controlling the phase of the voltage when the motor is changed to have 8 poles. [0033]
Conversely, when the input dehydration speed is 1400 rpm, the number of the poles of the motor is changed into 4, and then the motor is operated. That is, when the motor has 4 poles, the rotation speed of the motor is 1400 rpm. Here, the rotation speed of the motor can be controlled between 1000 rpm and 1400 rpm by controlling the voltage applied to the motor by controlling the phase of the voltage when the stator of the motor is changed to have 4 poles. [0034]
Therefore, the dehydration speed can be variously converted by changing the number of the poles of the stator of the motor, and converting the voltage applied to the motor when the number of the poles is changed. In the related arts, the rotation speed of the motor is controlled according to the preset dehydration speed, regardless of the kind and amount of the laundry put into the washing machine. Accordingly, even when the laundry is small, the motor is operated in the preset dehydration speed, to increase vibrations and noises of the washing machine. However, in accordance with the present invention, the dehydration speed is set on the basis of the amount of the laundry put into the washing machine, and the rotation speed of the motor is controlled according to the dehydration speed, which reduces vibrations and noises of the washing machine. [0035]
The phase control will now be explained in detail with reference to FIG. 4. FIG. 4 is a graph showing torque-speed curves of the motor in accordance with the present invention. As shown in FIG. 4, the laundry is dehydrated by rotating the drum in the dehydration speed N[0036] ₁, N₂and N₃where a load torque T_Lmeets input voltage V₁, V₂and V₃applied to the motor, by adjusting the input voltage V₁, V₂and V₃by controlling the phase. Here, the load torque T_Lis a torque applied to the drum.
The phase control of the present invention will now be described in more detail. [0037]
A Triac device which is a gate control semiconductor switch for alternating current power included in a phase control circuit is used to vary the speed of the induction motor when sine input voltage waveform, namely single phase power (for example, 220V/60 Hz) is applied. That is, the operation speed of the motor is converted by adjusting the output voltage V[0038] ₁, V₂and V₃by controlling a fire angle according to the input pulse signal of the Triac device.
In the case of the method for controlling the dehydration speed, when the dehydration speed selected by the user is 400 rpm, the number of the poles of windings of the stator is changed into 8, and the input voltage V[0039] ₃is applied to the motor as shown in the torque-speed curves of FIG. 4, and when the dehydration speed selected by the user is 600 rpm, the number of the poles of the motor is changed into 8, and the input voltage V₂is applied to the motor. In addition, when the dehydration speed selected by the user is 800 rpm, the number of the poles of the windings of the stator is changed into 8, and the input voltage V₁is applied to the motor. That is, the dehydration speed 800 rpm approximately obtained in the 8 poles of the stator can be varied in multiple steps by changing the input voltage applied to the motor by controlling the phase.
On the other hand, when the dehydration speed selected by the user is 1000 rpm, the number of the poles of the motor is changed into 4, and the input voltage V[0040] ₃is applied to the motor, and when the dehydration speed selected by the user is 1200 rpm, the number of the poles of the motor changed into 4, and the input voltage V₂is applied to the motor. In addition, when the dehydration speed selected by the user is 1400 rpm, the number of the poles of the motor is changed into 4, and the input voltage V₁is applied to the induction motor. That is, the dehydration speed 1400 rpm approximately obtained in the 4 poles of the motor can be varied in multiple steps by controlling the input voltage applied to the induction motor by controlling the phase.
Referring to FIG. 2, the steps for calculating the properties of the motor (S[0041] 15 and S19) calculate the dehydration speed sensed by the motor sensor adhered to the motor, and the torque and efficiency of the motor, and the steps for evaluating performance satisfaction (S20 and S16) evaluate performance satisfaction on the basis of the values calculated in the steps for calculating the properties of the motor. Here, the routine goes to the final steps or the steps for deciding phase control patterns according to the performance satisfaction results.
As discussed earlier, in accordance with the present invention, the method for controlling the dehydration speed of the washing machine converts the dehydration speed into two-step speed (800 rpm and 1400 rpm) by changing the number of the poles of the motor, and controlling the input voltage applied to the motor by controlling the phase, thereby converting the dehydration speed in multiple steps. [0042]
Moreover, the method for controlling the dehydration speed of the washing machine remarkably reduces noises and vibrations of the washing machine. [0043]
As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to be embraced by the appended claims. [0044]

Claims

What is claimed is:

1. A method for controlling a dehydration speed of a washing machine, comprising the steps of:

setting the dehydration speed on the basis of an amount of laundry put into the washing machine; and

controlling a rotation speed of a motor of the washing machine on the basis of the set dehydration speed.

2. The method of claim 1, wherein the step for controlling the rotation speed of the motor comprises the steps of:

changing a number of poles of the motor of the washing machine; and

controlling a voltage applied to the motor when the number of the poles is changed.

3. The method of claim 1, wherein the motor is an induction motor.

4. The method of claim 1, wherein the washing machine is a drum washing machine.

5. The method of claim 1, wherein the step for changing the number of the poles of the motor changes the number of the poles into 4 or 8.

6. The method of claim 1, wherein the step for changing the number of the poles of the motor comprises the steps of:

sensing a dehydration speed selected by the user; and

changing the number of the poles of the motor on the basis of the sensed dehydration speed.

7. The method of claim 1, wherein the step for controlling the voltage applied to the motor comprises a step for controlling the dehydration speed of the washing machine, by controlling the voltage applied to the motor by changing a phase of the voltage when the number of the poles of the motor is changed.

8. The method of claim 1, wherein the step for setting the dehydration speed on the basis of the sensed amount of the laundry converts the dehydration speed on the basis of the sensed amount of the laundry.

9. The method of claim 1, wherein the step for controlling the rotation speed of the motor of the washing machine on the basis of the set dehydration speed controls the dehydration speed by changing the number of the poles of the motor and controlling the phase of the voltage inputted to the motor.

10. The method of claim 2, wherein the step for controlling the voltage applied to the motor when the number of the poles is changed controls the phase of the voltage applied to the motor.

11. A method for controlling a dehydration speed of a drum washing machine comprising the steps of:

sensing a dehydration speed desired by a user;

changing the number of poles of an induction motor by the sensed dehydration speed; and

changing a dehydration speed through a phase control of an induction motor according to the changed number of poles.

12. The method of claim 11, wherein the number of poles of the induction motor is changed into 4 poles or 8 poles.

13. The method of claim 11, wherein the step for changing a dehydration speed through a phase control of the induction motor comprises the step for varying a voltage according to a sensed fire angle and supplying the voltage to the induction motor.

14. A method for controlling a dehydration speed of a drum washing machine comprising the steps of:

sensing the amount and the quality of the laundry;

determining a dehydration speed according to the sensed data;

changing the number of poles of an induction motor according to the determined dehydration speed; and

changing the dehydration speed through a phase control of a voltage that is inputted to the induction motor according to the changed number of poles.

15. The method of claim 14, wherein the number of poles of the induction motor is changed into 4 poles or 8 poles.

16. The method of claim 14, wherein the step for varying a dehydration speed through a phase control of the voltage comprises the steps of:

sensing a fire angle corresponding to the dehydration speed; and

varying a voltage that is inputted to the induction motor according to the sensed fire angle.