EP2194180B1

EP2194180B1 - Washing machine and sensing method of laundry weight contained therein

Info

Publication number: EP2194180B1
Application number: EP09156898.0A
Authority: EP
Inventors: Soon Bae Yang; Jun Hyun Park; Chang Joo Park; Jung Chul Choi
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2008-12-02
Filing date: 2009-03-31
Publication date: 2013-11-20
Anticipated expiration: 2029-03-31
Also published as: EP2194180A2; KR20100062655A; EP2194180A3

Abstract

A washing machine to re-perform sensing of the weight of laundry when an AC power is unstable is described. A zero-voltage detector detects a zero voltage of the AC power and generates a zero-voltage signal. If a count value counted according to the zero-voltage signal is greater than a maximum value, a microprocessor recognizes that the a voltage variation is generated due to abrupt power failure and if the count value is less than a minimum value, the microprocessor recognizes that a voltage variation is generated due to noise contained in the power. Then the microprocessor re-performs the sensing of the weight of laundry.

Description

BACKGROUND

1. Field

The present invention relates to a washing machine and a sensing method of the weight of laundry contained therein, and, more particularly, to a washing machine and a sensing method of the weight of laundry contained therein, which re-perform a laundry weight sensing process upon occurrence of an abnormal power voltage.

2. Description of the Related Art

Generally, a washing machine includes a rotating tub connected to a motor to contain washing laundry and washes or dehydrates the laundry by rotation by driving the motor.
A washing process and a dehydrating process include a laundry weight sensing process. To sense the weight of laundry, a method to measure the magnitude of the load of the motor and calculate the laundry weight therefrom has been disclosed and such a method has been widely applied to the washing machine.
The method to sense a laundry weight using the load of the motor can ensure reliable weight sensing when force generated from the motor satisfies an effectively controlled state.
If an alternating current (AC) power voltage is stably supplied to the washing machine, the motor is accurately controlled. However, if the AC power voltage is unstable, a voltage applied to the motor differs from a voltage of a control command, which influences the motor load to be measured. Accordingly, the weight of washing laundry is inaccurately sensed, and the washing process and the dewatering process may not be properly implemented.
WO 2008/003 710 discloses a washer or dryer, wherein before the washing process starts, the weight of the laundry placed in the washer or dryer is ascertained to be as close to actual values as possible. A speed controller compares a predetermined reference speed with the actual speed of the motor. The speed of the motor is kept at a determined level, and a control card regulates the motor voltage feed by monitoring the change of the voltage coefficient with respect to time, which is determined with the output signals of the speed controller. The control card has voltage coefficient values corresponding to each pair of load/water amounts in its memory. The voltage coefficient is observed by initially taking in a volume of water less than the amount necessary for washing. The voltage coefficient then continuously observes each increment while taking in water in incrementally increasing amounts. The load amount it is then decided by comparing the measured voltage coefficient with the value in memory.

SUMMARY

It is an object of the invention to provide a washing machine and a sensing method of the weight of laundry contained therein, which can accurately sense the weight of laundry by re-sensing the weight of laundry if an AC power voltage supplied to the washing machine is unstable.
Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
The object is solved by the features of the independent claims. Advantageous embodiments are disclosed by the sub claims.
The judging of whether the power voltage is abnormal may count a detection time of a zero voltage using a timer and judge abnormality according to a difference between a detection time of a previous zero voltage and a detection time of a current zero voltage.
The judging of whether the power voltage is abnormal may include determining whether the difference is greater than a preset maximum value or less than a preset minimum value, and if the difference is greater than the maximum value or less than the minimum value, judging that the power voltage is abnormal.
If an abnormal power voltage is generated, the re-performing of the sensing of the weight of laundry may be executed after a prescribed standby time.
If the laundry weight sensing process is divided into a plurality of intervals, the judging of whether the power voltage is abnormal may be executed whenever each interval is performed, and if an abnormal power voltage is generated, re-performing a corresponding interval.
The method may include detecting a zero voltage of an alternating current (AC) power and determining whether a power voltage is abnormal by comparing a difference between a detection time of a current zero voltage and a detection time of a previous zero voltage with a reference value.
The re-performing of the sensing of the weight of laundry may be executed, after waiting a set time from when the abnormal power voltage is generated and the set time has elapsed.
The power monitor may be a zero-voltage detector to detect a zero voltage of an AC power.
The controller may include a timer to count a detection time of a zero voltage of the zero-voltage detector and determine whether the power is abnormal according to a difference between a detection time of a previous zero voltage and a detection time of a current zero voltage, using the timer.
The controller may judge that the power is abnormal if the difference is greater than a maximum value or less than a minimum value.
The washing machine may include an AC power to drive the motor, a zero-voltage detector to detect a zero voltage of the AC power and generate a zero-voltage signal, and a microprocessor to determine whether the AC power is abnormal according to an input time of the zero-voltage signal and sense the weight of the laundry when the AC power is abnormal.
The microprocessor may include a timer to perform a count operation according to the zero-voltage signal, and judge that the AC power is abnormal due to abrupt power failure if a count value of the timer is greater than a first reference value.
The microprocessor may include a timer to perform a count operation according to the zero-voltage signal, and judge that the AC power is abnormal due to noise contained in the power if a count value of the timer is less than a second reference value.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a cross-sectional view illustrating the configuration of a washing machine according to an exemplary embodiment of the present invention;
FIG. 2 is a block diagram of a washing machine according to an exemplary embodiment of the present invention;
FIG. 3a is a view explaining a laundry weight sensing process according to an exemplary embodiment of the present invention;
FIG. 3b is a view illustrating a count value when a zero-voltage signal is input according to an exemplary embodiment of the present invention;
FIG. 4 is a view illustrating a stable AC power voltage;
FIG. 5 is a view illustrating a voltage variation due to noise included in an AC power voltage;
FIG. 6 is a view illustrating an example of the case where a voltage does not appear temporally at an AC power voltage due to abrupt power failure;
FIG. 7 is a flow chart illustrating a method to sense the weight of laundry according to an exemplary embodiment of the present invention;
FIG. 8 is a flow chart illustrating in detail a process to judge whether an AC power voltage is abnormal;
FIG. 9 is a flow chart illustrating a sensing method of the weight of laundry according to another exemplary embodiment of the present invention; and
FIG. 10 is a flow chart illustrating a sensing method of the weight of laundry according to a further exemplary embodiment of the present invention.

DETAILED DESCRIPTION

Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The embodiments are described below to explain the present invention by referring to the figures.
FIG. 1 is a cross-sectional view illustrating the configuration of a washing machine according to an exemplary embodiment of the present invention, FIG. 2 is a block diagram of a washing machine according to an exemplary embodiment of the present invention, FIG. 3a is a view explaining a laundry weight sensing process according to an exemplary embodiment of the present invention, and FIG. 3b is a view illustrating a count value when a zero-voltage signal is input according to an exemplary embodiment of the present invention.
Referring to FIG. 1, a washing machine 10 of the present invention includes a rotating tub 12 installed within a water tub 11 and a motor 13 to drive the rotating tub 12. In this embodiment, a universal motor comprised of a field coil and an armature is described as an illustrative example of the motor 13.
A belt 14 is connected between a rotating axis of the motor 13 and a pulley 15 coupled to one side of the rotating tub 12. The belt 14 transfers the rotating force of the motor 13 and rotates the rotating tub 12 using the rotating force.
As illustrated in FIG. 2, an AC power 20 supplied to the washing machine is converted into a direct current (DC) power in a rectifier 21 and the converted DC power is supplied to the motor 13. A microprocessor 30 receives a driving power through another rectifier 24 and a switched mode power supply (SMPS) 25, in addition to the AC power. Reference numeral 26 denotes a capacitor.
A power switch 22 connected to the AC power 20 is turned on or off by the microprocessor 30. Although in this embodiment the power switch 22 is described as being configured by a triac, the present invention is not limited thereto and a switch which can switch an input power under control of the microprocessor 30 may be used.
The microprocessor 30 increases or decreases a duty of a gate signal applied to the triac 22 to control a voltage applied to the motor 13.
A speed sensor 23 measures a motor speed and provides the microprocessor 30 with a pulse corresponding to the motor speed. The microprocessor 30 recognizes the motor speed using the provided pulse.
The speed sensor 23 may be comprised of a tachogenerator but any speed sensor which can measure a motor speed may be employed.
The microprocessor 30 senses the weight of laundry according to a previously stored program and varies the motor speed according to a laundry weight sensing process as illustrated in FIG. 3a.
In this embodiment, a method to perform two laundry weight sensing processes WT1 and WT2 is applied. However, it will be understood to those skilled in the art that the number of the laundry weight sensing processes is not limited thereto and may be changed.
Each laundry weight sensing process is divided into multiple steps. A first interval t1 or t11 is an accelerating interval to increase the motor speed to a set speed S; a second interval t2 or t12 is a standby interval for stabilization of the motor speed; a third interval t3 or t13 is an average duty calculation interval to calculate an average duty while the motor rotates the set number of rotations; a fourth interval t4 or t14 is an accelerating interval to increase the motor speed with a duty which is more increased by a prescribed ratio than the average duty; and a fifth interval t5 or t15 is a motor rotation time measurement interval to measure a single rotation time of the motor during the accelerating interval. The motor speed, the number of rotations, and the duty applied to each interval are not limited to specific numbers and they may vary in consideration of characteristics of the motor applied to the washing machine.
The washing machine according to this embodiment includes a power monitor 40 to monitor the state of the AC power 20. The power monitor 40 serves to monitor whether an AC power is provided without a variation of a voltage. The power monitor 40 is comprised of a zero-voltage detector to generate a zero-voltage signal when the AC power of a prescribed frequency is a zero voltage. However, an electric circuit which can confirm the variation state of a power voltage may be applied to the power monitor 40.
The microprocessor 30 includes a divider 31 to divide an input clock and a timer 32 to perform a counting operation using the divided clock.
The microprocessor 30 receives the zero-voltage signal and measures a detection time of the zero-voltage signal using the timer 32. For example, as illustrated in FIG. 3b, the timer 32 increases a count value according to the input of the zero-voltage signal. When the zero-voltage signal is input again, the counter 32 30 resets the count value and then increases the count value. The timer 32 repeats a process to the count value and reset the count value whenever the zero-voltage signal is input.
If the AC power is stably provided, an input power voltage V_i regularly generates a zero voltage in correspondence to a power frequency, as illustrated in FIG. 4.
As an example of an unstable AC power, if a power voltage including noise, as illustrated in FIG. 5, is input, a zero-voltage signal generated each time an input power is a zero voltage includes a signal, for example, 'C' appearing due to the noise, as well as a normal signal.
As illustrated in FIG. 3b, the count value counted by the timer 32 according to a normal zero-voltage signal may be reset by an abnormally generated zero-voltage signal and then may start count again. Thereafter, the count value is reset when a normal zero-voltage signal is input again. In this case, since a count value 'A' of the counter 32, which is generated by an abnormally generated zero signal due to noise, is less than a reference value ZC, the microprocessor 30 can recognize the unstable state of the AC power based on such a count value of the timer 32.
As another example of the unstable AC power, the AC power may be unstable due to abrupt power failure as illustrated in FIG. 6. Namely, an interval B during which a voltage does not appear temporally may occur in the middle of the AC power. Since a zero-voltage signal does not appear during the interval of abrupt power failure, the count value of the timer 32 is greater than the reference value ZC. Therefore, the microprocessor 30 can recognize the unstable state of the AC power based on such a count value of the timer 32. In this case, even if the abrupt power failure occurs, since the microprocessor 30 receives a power charged to the capacitor 26, the microprocessor 30 can execute a control operation.
If the microprocessor 30 judges that the voltage state of the AC power is unstable while sensing the weight of laundry, the microprocessor 30 stops the laundry weight sensing process and re-performs the laundry weight sensing process from the beginning. Various embodiments to re-perform the laundry weight sensing process when a voltage variation is unstable will be described hereinbelow.
A laundry weight sensing method according to an exemplary embodiment of the present invention is described with reference to FIGS. 7 and 8.
A washing machine applied to this exemplary embodiment senses the weight of laundry using the laundry weight sensing process in a washing process and a dehydrating process as described previously.
If the laundry weight sensing process is started, the microprocessor 30 monitors a voltage state of an AC power using a zero-voltage signal received from the zero-voltage detector 40 (step 50).
The microprocessor 30 varies a motor speed according to the laundry weight sensing process as illustrated in FIG. 3a. First, the microprocessor 30 drives the motor 13 to increase a motor speed to the set speed S. The set speed S may be, but is not limited to, 80 rpm in consideration of the state that laundry contained in a rotating tub is attached to an inner surface of the washing machine.
If the motor speed reaches the set speed, the microprocessor 30 enters a standby state to maintain the set speed for two seconds for example (step 52). Next, the microprocessor 30 calculates an average duty during 4 rotations of the motor (step 53).
The microprocessor 30 accelerates the motor speed with a duty greater than 1.5 times the average duty (step 54). In this case, the microprocessor 30 measures a single rotation time of the motor (step 55).
Thereafter, the microprocessor 30 judges whether an abnormal voltage is generated while monitoring an AC power (step 56). If an abnormal voltage is generated, the microprocessor 30 proceeds to step 50 to perform the laundry weight sensing process again and repeats the above-described operation.
Meanwhile, if no abnormal voltage is generated, the microprocessor 30 calculates a laundry weight according to the single rotation time of the motor (step 57).
A process to judge whether an abnormal voltage is generated in step 56 is described in detail with reference to FIG. 8.
The microprocessor 30 determines whether a zero-voltage signal is input (step 60). If the zero-voltage signal is input, the timer 32 is rest to start count. A count value of the timer 32 is increased until a next zero-voltage signal is input. The microprocessor 30 confirms an input time of the zero-voltage signal (step 61) and calculates a difference T between a count value ZC_i at an input time of a previous zero-voltage signal and a count value ZC_i-1 at an input time of a current zero-voltage signal (step 62).
The microprocessor 30 judges whether the difference T in a count value is greater than a preset maximum value T_MAX (step 63). If the difference T is not greater than the maximum value T_MAX, the microprocessor 30 judges whether the difference T is less than a preset minimum value T_MIN (step 64).
If the difference T is less than the preset minimum value T_MIN, the microprocessor 30 determines that an abnormal zero-voltage signal is generated by noise included in the AC power as illustrated in FIG. 5. If the difference T is greater than the preset maximum value T_MAX, the microprocessor determines that the zero-voltage signal is not generated by abrupt power failure as illustrated in FIG. 6. If such abnormality case is judged (step 65), the microprocessor 30 re-executes the laundry weight sensing process.
If the difference T is not greater than the maximum value T_MAX and not less than the minimum value T_MIN, the power voltage is judged to be normal (step 66) and the microprocessor 30 calculates the weight of laundry according to the single rotation time of the motor.
FIG. 9 is a flow chart explaining a sensing method of the weight of laundry according to another exemplary embodiment of the present invention.
As illustrated in FIG. 9, steps 70, 71, 72, 73, 74, 75, 76, and 77 execute the same operation as steps 50, 51, 52, 53, 54, 55, 56, and 57 shown in FIG. 7.
Additionally, if an AC power is unstable and thus an abnormal power voltage is generated, the microprocessor 30 enters a standby state (step 78) instead of directly starting a laundry weight sensing operation and judges whether a prescribed time, for example, one to two seconds has elapsed (step 79). If the prescribed time has elapsed, the microprocessor 30 proceeds to step 70 to re-execute the laundry weight sensing operation.
It is apparent that steps illustrated in FIG. 8 are identically applied to a process to judge whether the abnormal voltage is generated in FIG. 9.
FIG. 10 is a flow chart explaining a sensing method of the weight of laundry according to a further exemplary embodiment of the present invention.
As illustrated in FIG. 10, steps 80, 81, 83, 85, 87, 88, and 90 execute the same operation as steps 50, 51, 52, 53, 54, 55, and 57 shown in FIG. 7. Additionally, whenever each step ends, the microprocessor 30 monitors an AC power and judges whether an abnormal power voltage is generated ( steps 82, 84, 86, and 89). If the abnormal power voltage is generated, corresponding steps are re-executed.
It is apparent that steps illustrated in FIG. 8 are identically applied to a processor to judge whether the abnormal voltage is generated in FIG. 10.
As described above, since the laundry weight sensing process is re-performed when a power voltage applied to the motor varies due to an unstable AC power being supplied to the washing machine, the reliability of a laundry weight can be ensured and functions in a washing process and a dehydrating process to which the laundry weight sensing process is applied can be effectively executed.
Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the scope of which is defined in the claims.

Claims

A sensing method of the weight of laundry in a washing machine (10) including a rotating tub (12) and a motor (13) to rotate the rotating tub, the method comprising the following steps:
i) sensing the weight of laundry by varying (51, 52, 54; 71, 72, 74; 81, 83, 87) a speed of the motor (13) according to a laundry weight sensing process:

ii) judging (56, 76, 82, 86, 89) whether a power voltage supplied to the motor (13) is abnormal while sensing the weight of laundry, and

iii) re-performing the sensing of the weight of laundry when the power voltage is abnormal.
The method according to claim 1, wherein the judging of whether the power voltage is abnormal counts (60) a detection time of a zero voltage using a timer (32) and judges (63, 64) abnormality according to a difference (62) between a detection time of a previous zero voltage and a detection time of a current zero voltage.
The method according to claim 2, wherein the judging of whether the power voltage is abnormal includes:
determining (63, 64) whether the difference (62) is greater than a preset maximum value or less than a preset minimum value; and

if the difference is greater than the maximum value or less than the minimum value, judging (65) that the power voltage is abnormal.
The method according to claim 2, wherein, if an abnormal power voltage is generated, the re-performing of the sensing of the weight of laundry is executed after a prescribed standby time.
The method according to claim 2, wherein, if the laundry weight sensing process is divided into a plurality of intervals, the judging of whether the power voltage is abnormal is executed whenever each interval is performed, and if an abnormal power voltage is generated, re-performing a corresponding interval.
A method according to claim 1, wherein step ii) comprises:
detecting a zero voltage of an alternating current (AC) power;

determining whether a power voltage is abnormal by comparing the difference (T) between a detection time (ZC_i-1) of a current zero voltage and a detection time (ZC_i) of a previous zero voltage with a reference value (T_MAX, T_MIN).
The method according to claim 6, wherein the re-performing of the sensing of the weight of laundry is executed, after waiting a set time from when the abnormal power voltage is generated and the set time has elapsed.
A washing machine (10) including a rotating tub (12) and a motor (13) to rotate the rotating tub, the washing machine comprising:
a power monitor (40) to generate a signal to monitor a power supplied to the motor (13), and

a controller (30) to determine whether the power is abnormal according to the signal received from the power monitor, and re-perform sensing of the weight of laundry when the power is abnormal, and performing the method according to claim 1.
The washing machine according to claim 8, wherein the power monitor (40) is a zero-voltage detector to detect a zero voltage of an AC power (20).
The washing machine according to claim 9, wherein the controller (30) includes a timer (32) to count a detection time of a zero voltage of the zero-voltage detector (40) and determines whether the power is abnormal according to a difference (T) between a detection time (ZC_i) of a previous zero voltage and a detection time (ZC_i-1) of a current zero voltage, using the timer (32).
The washing machine according to claim 10, wherein the controller (30) judges that the power is abnormal if the difference (T) is greater than a maximum value (T_MAX) or less than a minimum value (T_MIN).
The washing machine according to claim 8, additionally comprising an AC power (20) to drive the motor;
a zero-voltage detector (40) as a power monitor to detect a zero voltage of the AC power (20) and to generate a zero-voltage signal, and
a microprocessor (30) as said controller to determine whether the AC power (20) is abnormal according to an input time of the zero-voltage signal and to re-perform sensing of the weight of laundry when the AC power is abnormal.
The washing machine according to claim 12, wherein the microprocessor (30) includes a timer (32) to perform a count operation according to the zero-voltage signal, and judges that the AC power is abnormal due to abrupt power failure if a count value of the timer (32) is greater than a first reference value.
The washing machine according to claim 12, wherein the microprocessor (30) includes a timer (32)to perform a count operation according to the zero-voltage signal, and judges that the AC power is abnormal due to noise contained in the power if a count value of the timer (32) is less than a second reference value.