KR101375714B1 - Method for detecting laundry weight of drum type washing machine - Google Patents

Abstract

The present invention relates to a method for detecting the amount of laundry in a drum washing machine. More particularly, the present invention compensates for the same amount of laundry by using an input voltage component applied to the motor, By compensating the fluctuation data in consideration of the fluctuation of the input voltage and the frequency fluctuation of the input power source, it is possible to obtain a constant filling value for the same laundry weight and to detect the weight of the laundry more precisely.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a drum type washing machine,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of detecting the amount of laundry in a drum type washing machine, and more particularly, to a method of detecting a laundry amount in a drum type washing machine.

Generally, the drum type washing machine has a fixing tank and a drum-type rotary tank rotatably installed in the fixing tank. The washing machine is used to wash the laundry by using a drop generated by the rotation of the rotary tank.

In small and medium drum type washing machines adopting universal motors, phase control method using triac is used for motor control. The phase control method using the triac calculates the phase corresponding to the magnitude of the applied voltage corresponding to the motor speed to be operated and the voltage to be applied to the motor and outputs a signal to the triac based on the zero cross signal of the power supply voltage To operate the motor.

Generally, in the drum washing machine, the drum containing the laundry is accelerated to a uniform distribution of the laundry in the drum, and then a predetermined constant torque (or voltage) The acceleration time is detected in proportion to the weight of the laundry, and the weight of the laundry is estimated. In order to apply a constant torque, a constant current is applied or a constant voltage is applied for control convenience.

However, in the conventional method, the weight of the laundry is measured through the time taken to reach a certain speed by applying a constant torque or a constant voltage. Generally, a drum washing machine adopting a universal motor has a phase control method using a triac because of the motor control characteristic, even if a certain phase is applied to the motor, even if the weight of the same laundry is changed according to the variation of the input voltage and the frequency of the input power source, And the frequency of the input power source fluctuates. Generally, in household appliances, the voltage fluctuation of 10% and the frequency fluctuation of 5% should be considered. Therefore, in the drum washing machine adopting the phase control method, The acceleration time varies depending on the distribution state of the laundry in the drum and the friction with the door glass of the drum or the distinction of the weight detection value becomes large and the distinction of data by weight becomes unclear.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a method for detecting the amount of laundry in a drum washing machine, which can more accurately detect the weight of laundry laid on the drum washing machine.

According to another aspect of the present invention, there is provided a method of detecting a drum washing machine comprising the steps of: accelerating a motor to a first rotational speed; maintaining a constant speed after reaching the first rotational speed; A step of calculating an average voltage to be applied to the motor, a step of applying a voltage of an integer multiple of the calculated average voltage to the motor to accelerate the motor to a second rotational speed, And calculating the weight of the laundry using the average voltage.

The step of accelerating the motor to the second rotation speed is characterized by accelerating the minimum speed from the minimum speed by obtaining a minimum speed of the motor in a section maintaining the constant speed.

And finally calculating the weight of the laundry using the predetermined weight correction value corresponding to the average voltage applied to the motor after the weight calculation step. Here, the weight correction value may be preset according to the magnitude of the average voltage applied to the motor.

According to the present invention, even in the same amount of laundry, the distribution state of the laundry in the drum, the acceleration time variation due to the door glass friction, etc. are compensated by the input voltage component applied to the motor, and the variation of the input voltage and the frequency variation of the input power supply are considered Therefore, it is possible to obtain a certain amount of weight for the same laundry weight, and it is possible to detect the weight of the laundry more precisely.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 schematically shows the overall configuration of a drum washing machine according to an embodiment of the present invention. 1, the drum type washing machine according to the embodiment of the present invention includes a housing 1 having an approximately box shape and forming an outer appearance of the drum type washing machine, (Hereinafter referred to as " drum ") in which a plurality of dewatering holes 3a are formed on the surface of the rotary drum 2, And a motor 5 for rotating the rotary tub 3 in the washing tub 4 to perform a washing process, a rinsing process and a dewatering process.

In the operation of the drum washing machine having the above-described configuration, the rotary tub 3 is rotated by the driving force of the motor 5 to perform a washing cycle, a rinsing cycle, and a dewatering cycle. The motor is supplied with a phase-controlled power of an alternating-current power supplied from an alternating-current power source by a power conversion device composed of a converter and an inverter. The motor 5 adjusts the input voltage applied to the motor through the phase control so that the rotational force of the motor 5 varies, and the rotary tub 3 containing the laundry is rotated at a predetermined speed. This phase control is performed through a phase control circuit including a triac element for varying the speed of the motor 5 upon application of the AC power. The triac adjusts the rotational speed of the motor 5 by changing the magnitude of the desired output voltage by controlling the input voltage to be applied to the excitation point according to the signal of the input pulse separately applied. At this time, as the firing angle control is increased, the magnitude of the voltage decreases and the rotational speed of the motor 5 decreases from high speed to low speed. As the control of the firing angle decreases, the voltage increases accordingly, ) Is increased from low speed to high speed.

4 and 5, in the present invention, in order to eliminate the weight measurement deviation due to unbalance of load, the motor speed Wrpm1 at which the laundry in the drum 3 uniformly adheres to the inner wall surface of the drum 3 as uniformly as possible, (S100, S110). When the motor speed reaches a predetermined number of revolutions (Wrpm1), the motor speed is maintained at a constant speed by a closed loop control such as PI control for a predetermined time (S120). An average torque or an average voltage proportional to the weight of laundry to be applied to the motor 5 in the constant velocity section is obtained (S130). (Or voltage) of an average torque (or an average voltage) is applied to a motor 5 to accelerate to an arbitrary drum revolution speed (drum revolution) (or an arbitrary motor speed Wrpm2) (S140, S150). At this time, the average speed and the lowest speed are obtained at the constant speed (Wrpm1) to obtain the consistency of the amount data by making the acceleration time constant at the acceleration, and the drum 3 is accelerated from the lowest speed. When the drum 3 rotates by one drum, the acceleration time is obtained and the motor 5 is stopped (S160, S170). Then, the weight of the laundry is calculated using the average torque value (average voltage or average current) applied to the motor and the acceleration time (S180). At the same time, the final weight of the laundry is calculated by applying the weight correction value to compensate for the variation of the input voltage and the frequency variation of the input power source through the voltage linearization described later (S190).

Hereinafter, this will be described in more detail.

First, the equation of motion of the rotating body is given by the following equation [1].

식 [1]

Equation [1]

J is the inertial coefficient of the drum including the laundry, Te is the input torque applied to the motor, B is the friction coefficient, TL is the load torque, and W is the angular velocity of the drum.

Since the friction coefficient B is smaller than the input torque Te and can be ignored, the acceleration instantaneous load torque TL is smaller than the inertia coefficient J of the drum 3 and can be ignored.

)로 운전 중인 드럼(3)을 정수 N배 토크로 드럼을 가속 할 경우 세탁물을 포함한 드럼(3)의 관성계수 Jm은 다음의 식 [2]와 같이 유도할 수 있다.An average applied torque obtained at a speed at which the laundry starts to stick to the inner wall surface of the drum 3

), The inertial coefficient Jm of the drum 3 including the laundry can be derived as shown in the following equation [2] when the drum 3 accelerates the drum at a constant N-fold torque.

식 [2]

Equation [2]

The average torque Te of the applied load in the constant- Can be expressed in a manner proportional to the current applied to the motor 5, and can be redefined in the direct field method as expressed by the following equation [3].

식 [3]

Equation [3]

Since equation [3] is substituted into equation [2] and the current is proportional to the voltage, the equation for the weight of laundry Jm can be expressed as [4].

식 [4]

Equation [4]

The voltage Va applied to the motor 5 can be expressed simply by the following equation [5]

식 [5]

Equation [5]

Vavg is the average value of the input voltage, Duty is the average duty at Wrpm1, N is an integral multiple of the average duty required for acceleration, and Frequency is the frequency of the power supply voltage.

는 세탁기 드럼 1회전 2π로 그 값이 일정하고, (N-1)항도 N값이 일정상수 값으로 일정하므로 임의의 상수로 둘 수 있다.이러한 조건을 이용해 식 [5]를 식 [4]에 대입하면 세탁기의 세탁물 무게 Jm 는 최종적으로 식 8과 같이 표현 할 수 있다.In the method for detecting the drum washing machine according to the embodiment of the present invention, for example, by calculating the drum washing amount data based on acceleration up to the drum 1 rotation (2?),

Can be set to an arbitrary constant since the value of N is constant with a constant value of 2, and the value of (N-1) N is constant constant value. The weight Jm of the laundry in the washing machine can be finally expressed as Equation 8.

식 [6]

Equation [6]

However, the weight Jm of the laundry calculated in Equation [6] is a condition where the size and frequency of the applied input power are constant.

The power supply environment of the actual drum washing machine should consider ± 10% voltage fluctuation and ± 5% frequency fluctuation, and for the phase control using the triac, it is easily affected by such power supply voltage fluctuation. The amount of fluctuation data varies greatly.

In order to solve such a problem, it is necessary to linearize the amount data according to the voltage magnitude. In the voltage linearization, the amount of the laundry is detected by the size of the voltage for the same laundry, Or can be linearized in a quadratic fashion.

That is, for the same laundry, the volume data for each voltage size is calculated, and the weight of the final laundry can be expressed by the following equation [7] through the voltage linearization operation.

식 [7]

Equation [7]

Here, ax + b represents the weight correction value expressed by the voltage linearization linear equation. In the drum type laundry detection method according to the embodiment of the present invention, instead of estimating the weight of the laundry by detecting only the acceleration time which reaches the arbitrary speed in the existing drum type detection system, The weight is estimated to improve the discrimination power and resolution of the bulk data, and the same bulk data can be obtained for the fluctuating power supply voltage through the voltage linearization.

The method of detecting the amount of laundry in the drum washing machine according to the embodiment of the present invention takes into account fluctuations of the input voltage and frequency of the input power source and measures the distribution state of the laundry in the drum and the acceleration time variation due to the door glass friction, 5), it is possible to obtain a certain weight value for the same laundry weight, and to detect the weight of the laundry more precisely.

FIG. 3 and FIG. 4 show the weight data of the clothes according to the number of general towels perceived by applying the method of detecting the amount of laundry in the drum type washing machine according to the embodiment of the present invention. The overlapping of weight detection data according to the number of towels is reduced, the weight discrimination becomes more precise, and the weight detection classification for more than 40 towels is more precise. The weight detection resolution is 0.56kg (weighing detection resolution is 1.15kg in the same weight / model drum washing machine according to the conventional method), and it can be understood that it has more accurate weight detection resolution and discrimination power.

1 is a schematic cross-sectional view of a drum washing machine according to an embodiment of the present invention.

2 is a view for explaining a concept of detecting the weight of laundry in a drum type washing machine according to an embodiment of the present invention.

FIG. 3 is a control flowchart of a method for detecting the amount of laundry in the drum type washing machine according to the embodiment of the present invention.

FIG. 4 is a view showing the weight data for detecting the weight of clothes in the drum washing machine according to the embodiment of the present invention.

FIG. 5 is a diagram illustrating the performance of detecting the weight of the clothes by the method of detecting the amount of laundry in the drum type washing machine according to the embodiment of the present invention.

[Description of the Reference Numerals]

1: Housing 2: Fixture

3: rotating tank 4: washing tub

5: Motor

Claims (4)

Accelerating the motor to a first rotational speed, Maintaining a constant speed after reaching the first rotation speed; Calculating an average voltage applied to the motor while maintaining the constant speed; Applying an integer multiple of the calculated average voltage to the motor to accelerate to a second rotational speed; And calculating the weight of the laundry by using an acceleration time for accelerating the motor to the second rotation speed and the average voltage. The method according to claim 1, Wherein the step of accelerating the motor to the second rotational speed comprises determining a minimum speed of the motor in an interval in which the constant speed is maintained and accelerating the motor based on the minimum speed. The method according to claim 1, And finally calculating the weight of the laundry using the weight correction value preset to correspond to the average voltage applied to the motor after the weight calculation step. The method of claim 3, Wherein the weight correction value is previously set for each magnitude of an average voltage applied to the motor.

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