U.S. patent application number 13/383027 was filed with the patent office on 2012-05-03 for washing machine.
This patent application is currently assigned to PANASONIC CORPORATION. Invention is credited to Koichi Kubo, Makoto Oyama, Toshihiko Yasui.
Application Number | 20120103026 13/383027 |
Document ID | / |
Family ID | 43449150 |
Filed Date | 2012-05-03 |
United States Patent
Application |
20120103026 |
Kind Code |
A1 |
Oyama; Makoto ; et
al. |
May 3, 2012 |
WASHING MACHINE
Abstract
A washing machine includes a cabinet, an outer tank, an inner
tank, a circulation tube, and a circulation pump. The outer tank is
held in the cabinet. The inner tank is rotatably mounted in the
outer tank so as to accommodate and stir laundry. The circulation
tube draws washing water kept in the outer tank and returns it to
the outer tank. The circulation pump is located at some midpoint in
the circulation tube so as to circulate the washing water. The
washing machine further includes, at some midpoint in the
circulation tube, a washing water-condition detector for detecting
the condition of the washing water. This structure ensures the
amount of washing water circulating through the washing
water-condition detector, without depending on the operation of the
inner tank. Thus, the washing machine can detect the degree of
contamination of washing water with high accuracy while maintaining
its washing efficiency.
Inventors: |
Oyama; Makoto; (Osaka,
JP) ; Yasui; Toshihiko; (Nara, JP) ; Kubo;
Koichi; (Shiga, JP) |
Assignee: |
PANASONIC CORPORATION
Kadoma-shi, Osaka
JP
|
Family ID: |
43449150 |
Appl. No.: |
13/383027 |
Filed: |
July 12, 2010 |
PCT Filed: |
July 12, 2010 |
PCT NO: |
PCT/JP2010/004505 |
371 Date: |
January 9, 2012 |
Current U.S.
Class: |
68/13R |
Current CPC
Class: |
D06F 34/22 20200201;
D06F 39/085 20130101; D06F 39/083 20130101; D06F 33/00 20130101;
D06F 2202/02 20130101; D06F 2202/10 20130101; D06F 2204/082
20130101 |
Class at
Publication: |
68/13.R |
International
Class: |
D06F 33/00 20060101
D06F033/00; D06F 39/08 20060101 D06F039/08; D06F 21/00 20060101
D06F021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 14, 2009 |
JP |
2009-165660 |
Claims
1. A washing machine comprising; a cabinet; an outer tank held in
the cabinet; an inner tank rotatably mounted in the outer tank, the
inner tank accommodating laundry; an agitating portion for
agitating the laundry; a circulation tube for drawing washing water
kept in the outer tank and returning the washing water to the
inside of the outer tank; a circulation pump located at some
midpoint in the circulation tube, the circulation pump circulating
the washing water; and a controller for controlling operations of
the agitating portion and the circulation pump, wherein the washing
machine further includes, at some midpoint in the circulation tube,
a washing water-condition detector for detecting a condition of the
washing water.
2. The washing machine of claim 1, wherein the controller operates
the circulation pump intermittently during a washing step; and the
washing water-condition detector detects a condition of the washing
water when the circulation pump is stopped.
3. The washing machine of claim 1, wherein the circulation tube
allows the washing water to be injected into the inner tank.
4. The washing machine of claim 1, wherein the controller
synchronizes operations of the agitating portion and the
circulation pump.
5. The washing machine of claim 1, wherein the controller stops the
operation of the agitating portion when a predetermined time has
passed after having stopped the circulation pump.
6. The washing machine of claim 1, wherein the controller drives
the circulation pump during a rinsing step.
7. The washing machine of claim 1, wherein the agitating portion is
the inner tank, and the laundry is stirred by rotation of the inner
tank.
8. The washing machine of claim 1, further comprising: an agitator
rotatably mounted on an inner bottom of the inner tank, wherein the
agitating portion is the agitator, and the laundry is stirred by
rotation of the agitator.
Description
TECHNICAL FIELD
[0001] The present invention relates to a washing machine which
controls its operation according to the condition of washing
water.
BACKGROUND ART
[0002] A conventional washing machine of this type is disclosed in
Japanese Patent Unexamined Publication No. H4-240485 (Patent
Literature 1). FIG. 10 is a sectional view of the washing machine
disclosed in Patent Literature 1. The machine includes cabinet 1,
outer tank 2, inner tank 3, drive motor 4, circulation tube 5,
turbidity sensor 6, and controller 7. Cabinet 1 includes outer tank
2.
[0003] Outer tank 2 includes inner tank 3, which has a bottomed
cylindrical shape. Inner tank 3 accommodates laundry such as
clothes, and rotates around a horizontal axis. Drive motor 4
rotates inner tank 3. Turbidity sensor 6, which detects the
turbidity of the washing water, is located at some midpoint in
circulation tube 5. Circulation tube 5, which allows the washing
water to circulate, is located outside outer tank 2.
[0004] The rotation of inner tank 3 allows the washing water to
circulate through circulation tube 5, thereby preventing detergent
and stains from accumulating at the bottom of outer tank 2. The
rotation of inner tank 3 also makes the concentration of the
washing water uniform between outer tank 2 and circulation tube 5.
As a result, turbidity sensor 6 can detect the degree of
contamination of the uniformly concentrated washing water from the
degree of its turbidity. Controller 7 determines the degree of
contamination of the laundry based on the detected degree of
contamination of the washing water. When the laundry is not heavily
dirty, controller 7 selects a short wash time to optimize its
length.
[0005] As described above, in the conventional washing machine, the
rotation of inner tank 3 allows washing water to circulate through
circulation tube 5. It is therefore necessary to rotate inner tank
3 at high speed enough to circulate the washing water. Inner tank 3
also functions as an agitating portion for agitating laundry. The
laundry is washed by being raised and dropped repeatedly by the
rotation of inner tank 3. This washing method is referred to as
beat wash. Inner tank 3 has an optimum speed of rotation for beat
wash. When inner tank 3 rotates at a higher speed than the optimum
speed, the laundry is stuck to the rotating inner surface of inner
tank 3. In this situation, beat wash is impossible to be performed,
thereby reducing the washing efficiency of the washing machine. In
the conventional washing machine, inner tank 3 is rotated at the
optimum speed for beat wash so as to maintain the washing
efficiency. It is therefore impossible, at the optimum speed of
rotation, to circulate a sufficient amount of washing water through
circulation tube 5. As a result, it takes time to make the
concentration of the washing water uniform between outer tank 2 and
circulation tube 5. This causes turbidity sensor 6 to have low
detection accuracy.
SUMMARY OF THE INVENTION
[0006] The present invention provides a washing machine, which can
detect the degree of contamination of washing water with high
accuracy while maintaining its washing efficiency.
[0007] The washing machine of the present invention includes a
cabinet, an outer tank held in the cabinet, an inner tank rotatably
mounted in the outer tank so as to accommodate the laundry, and an
agitating portion for agitating the laundry. The washing machine
further includes a circulation tube, a circulation pump, and a
controller. The circulation tube draws washing water kept in the
outer tank and returns it to the outer tank. The circulation pump
is located at some midpoint in the circulation tube so as to
circulate the washing water. The controller controls the operation
of the agitating portion and the circulation pump. The washing
machine further includes, at some midpoint in the circulation tube,
a washing water-condition detector for detecting the condition of
the washing water.
[0008] This structure ensures the amount of washing water
circulating through the washing water-condition detector, without
depending on the operation of the agitating portion. Thus, the
washing machine can detect the degree of contamination of the
washing water with high accuracy while maintaining its washing
efficiency.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a sectional view of an example of a washing
machine according to a first exemplary embodiment of the present
invention.
[0010] FIG. 2 is a sectional view of an example of a discharge port
of the washing machine according to the first exemplary
embodiment.
[0011] FIG. 3 is a sectional view of another example of the
discharge port of the washing machine according to the first
exemplary embodiment.
[0012] FIG. 4 is a sectional view of another example of the washing
machine according to the first exemplary embodiment.
[0013] FIG. 5 is a sectional view of a washing water-condition
detector of the washing machine according to the first exemplary
embodiment.
[0014] FIG. 6 is a sectional view showing another operation of the
discharge port according to the washing machine according to the
first exemplary embodiment.
[0015] FIG. 7 is a sectional view of another example of the washing
machine according to the first exemplary embodiment.
[0016] FIG. 8 is a sectional view of another example of the washing
machine according to the first exemplary embodiment.
[0017] FIG. 9 is a sectional view of another example of the washing
machine according to the first exemplary embodiment.
[0018] FIG. 10 is a sectional view of a conventional washing
machine.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
First Exemplary Embodiment
[0019] FIG. 1 is a sectional view of an example of a washing
machine according to a first exemplary embodiment of the present
invention. Cabinet 21 includes outer tank 24 supported by spring
22, attenuator 23, and other members. Outer tank 24 includes inner
tank 25 rotatably mounted therein. Drive motor 26, which rotates
inner tank 25, is located on the rear surface of outer tank 24 (the
right side in FIG. 1). This washing machine is a drum type washing
machine where the axis of rotation of inner tank 25 is either
horizontal or inclined upwardly toward the front (the left side in
FIG. 1). Cabinet 21 further includes door 27 to open and close
front opening 24a of outer tank 24. Cabinet 21 and door 27 are
sealed with water-seal packing 28. Inner tank 25 has a cylindrical
inner surface, which is provided with a plurality of projections
29. Projections 29 raise the laundry when inner tank 25 is rotated
at low speed.
[0020] Cabinet 21 further includes, at its top, feed valve 30 and
detergent inlet 31. Fed valve 30 has feed-water inlet 30a, which is
connected to one end of a feed-water hose (not shown). Detergent
inlet 31 keeps detergent put by the user before washing. Cabinet 21
further includes feed-water tube 32 and drainage tube 36.
Feed-water tube 32 connects feed valve 30 and detergent inlet 31,
and also connects detergent inlet 31 and outer tank 24. The other
end of the feed-water hose is connected to the water service
pipe.
[0021] Outer tank 24 has water intake opening 33 at its lowermost
part. Water intake opening 33 is connected to drainage tube 36 via
drain filter 34 and drain valve 35. Drainage tube 36 allows washing
water to be discharged to the outside of washing machine. The
washing machine further includes circulation tube 37, which is
divided into two parts: one leads to water intake opening 33 and
the other leads to drain valve 35. Circulation tube 37 returns the
washing water exhausted from water intake opening 33 to outer tank
24. Circulation tube 37 has discharge port 38, which is
communicated with outer tank 24. Discharge port 38 allows the
washing water to be injected into inner tank 25. The tubes
extending between water intake opening 33 and discharge port 38 are
referred to as circulation tube 37. The washing machine further
includes, at two positions in circulation tube 37, circulation pump
39 and washing water-condition detector 40. Circulation pump 39
circulates washing water through circulation tube 37. Washing
water-condition detector 40 detects the condition of the washing
water. As described above, circulation tube 37 is divided into two
parts: one leads to water intake opening 33 and the other leads to
drain valve 35. Alternatively, circulation tube 37 may be
communicated with a water intake opening (not shown) of drainage
tube 36 different from water intake opening 33.
[0022] FIG. 2 is a sectional view of an example of discharge port
38 of circulation tube 37 of the washing machine according to the
present exemplary embodiment. Discharge port 38 located between
outer and inner tanks 24 and 25 allows washing water to be injected
into inner tank 25 through between outer and inner tanks 24 and 25
as shown in "B" in FIG. 2. Discharge port 38 may alternatively be
located at an exposed portion of outer tank 24 as shown in the
sectional view of FIG. 3 so that washing water can be injected into
inner tank 25 as shown in "C" in FIG. 3. Discharge port 38 may
alternatively be located between outer and inner tank 24 and 25 as
shown in the sectional view of FIG. 4. In this case, the washing
water is injected not into inner tank 25, but between outer and
inner tank 24 and 25.
[0023] FIG. 5 is a sectional view of washing water-condition
detector 40. Detector 40 is composed of optical sensor 41 and
electrode sensor 42. Optical sensor 41 detects the turbidity of
washing water, and electrode sensor 42 detects the electrical
conductivity of the washing water. Optical sensor 41 is composed of
light-emitting element 43 and light-receiving element 44.
Light-emitting element 43 can be, e.g., an LED, and light-receiving
element 44 can be, e.g., a phototransistor. Light-emitting element
43 and light-receiving element 44 are located substantially
horizontally and with circulation tube 37 therebetween. Electrode
sensor 42 is composed of a pair of electrodes 45a and 45b on one
side of the side wall of circulation tube 37.
[0024] The washing machine further includes c 46, which controls
the operations of drive motor 26, feed valve 30, drain valve 35,
circulation pump 39, and other components. Controller 46 further
receives the output of washing water-condition detector 40, and
performs calculation to detect the degree of contamination of
washing water.
[0025] The following is a description of the operation of the
washing machine of the present exemplary embodiment. The user opens
door 27, loads laundry such as clothes into inner tank 25, and
closes door 27. The user then presses the start button to start the
operation of the washing machine. When the operation is started,
controller 46 drives drive motor 26 to estimate the weight of the
clothes from the load of drive motor 26. Controller 46 displays a
necessary amount of detergent on a display unit (not shown)
according to the estimated amount of clothes. The user then pulls
out detergent inlet 31, pours the displayed amount of detergent,
and pushes back detergent inlet 31.
[0026] When a predetermined time has passed, controller 46 opens
feed valve 30 to feed water from the water service pipe (not
shown). The water is supplied into outer tank 24 through feed-water
tube 32. After passing through detergent inlet 31 containing
detergent, the water is supplied to outer tank 24 as
detergent-containing washing water.
[0027] Controller 46 drives drive motor 26 to rotate inner tank 25
as soon as the water starts to be fed. When the washing water
(water) reaches a predetermined amount, feed valve 30 is closed.
Inner tank 25, on the other hand, continues to be rotated. Along
with the rotation of inner tank 25, the clothes are repeatedly
raised to the top of inner tank 25 by three projections 29 on the
inner surface of inner tank 25 and are dropped off the inner
surface. This beat wash accelerates the cleaning of the laundry.
The beat wash has an optimum speed of rotation: too high or too low
a speed will reduce the washing efficiency.
[0028] When the clothes are washed for a predetermined time,
controller 46 opens drain valve 35. The washing water is discharged
from drainage tube 36 to the outside of the washing machine. Next,
controller 46 performs a spin-drying step by rotating inner tank 25
at high speed to remove water from the laundry. Controller 46 then
stops inner tank 25, opens feed valve 30 to feed water to a
predetermined feed-water level, and performs a spin-drying step by
rotating inner tank 25 again. After performing the spin-drying step
and the spin-drying step about two times, controller 46 performs
another spin-drying step. As a result, the washing process is
completed.
[0029] The following is a description of the operation of washing
water-condition detector 40. Optical sensor 41 detects the
turbidity of the washing water. The portion of circulation tube 37
that is sandwiched between light-emitting element 43 and
light-receiving element 44 is made of a resin having light
transmission properties. This allows light-receiving element 44 to
receive the light that has been emitted from light-emitting element
43 and then passed through the washing water in circulation tube
37. Light-receiving element 44 outputs a signal according to the
strength of the received light. Controller 46, which is composed,
e.g., of a microcomputer, receives the signal, converts it into a
voltage, and outputs the voltage. Light which passes through the
washing water attenuates according to the degree of turbidity of
the washing water. When, for example, light-receiving element 44
receives a small amount of light, this means that the degree of
turbidity of the washing water is high. In other words, the washing
water is contaminated. When, on the other hand, light-receiving
element 44 receives a large amount of light, this means that the
degree of turbidity of the washing water is low. Thus, the degree
of turbidity of the washing water is quantitatively detected from
the amount of light received by light-receiving element 44. The
stains in the laundry dissolve in the washing water and make the
washing water turbid. Therefore, when the degree of turbidity of
washing water is high, the laundry is estimated to contain a large
amount of stains.
[0030] Electrode sensor 42 measures the electrical conductivity of
washing water. This measurement can be performed for example as
follows. An RC oscillation circuit is composed of the impedance of
the washing water between electrodes 45a and 45b, and a capacitor
of a control circuit (not shown). Controller 46 outputs a change in
the impedance of the washing water as a change in the frequency,
and then converts the change in the frequency into a voltage value.
When the laundry contains a large amount of sweat and other stains,
the electrolyte composition of the sweat and other stains dissolve
in the washing water. As a result, the washing water has a high
electrical conductivity. For this reason, the amount of sweat and
other stains in the laundry can be estimated by quantitatively
detecting the electrical conductivity of the washing water.
[0031] As described above, the degree of contamination of laundry
such as clothes is estimated by optical sensor 41 and electrode
sensor 42. More specifically, the degree of contamination is
estimated by detecting the change with time of the outputs of
optical sensor 41 and electrode sensor 42, and then calculating the
difference between the outputs in a certain period. The degree of
contamination can alternatively be estimated by combining the
outputs of optical sensor 41 and electrode sensor 42. The estimated
degree of contamination of the laundry is used to control the
washing step and the spin-drying step. When the laundry is not
heavily dirty, the washing step is shortened, or a smaller amount
of water is used in the washing step and the spin-drying step. This
can save water, electric power, and operating time.
[0032] The degree of turbidity of the washing water may also be
changed by the detergent contained in the washing water. The
electrical conductivity of the washing water may be increased by a
component of the detergent in the washing water. Therefore, washing
water-condition detector 40 can detect the type and the amount of
the detergent, for example, immediately after water is supplied
into outer tank 24. Thus, washing water-condition detector 40 can
detect not only the degree of contamination of washing water.
Detector 40 can also detect the type and the amount of the
detergent in the washing water based on the degree of turbidity and
the electrical conductivity of the washing water.
[0033] To increase the correlation between the detection result of
washing water-condition detector 40 and the amount of stains on the
clothes, it is necessary to have a unique determination algorithm.
The algorithm can be, for example, the absolute value, the change
rate, or other factors of a detection value. In the present
exemplary embodiment, washing water-condition detector 40 is
located in circulation tube 37. This prevents optical sensor 41 and
electrode sensor 42 from being smeared with stains or affected by
the agitating of the washing water. Therefore, any determination
algorithm other than the above-described ones can contribute to an
improvement in the detection accuracy. For example, the degree of
contamination of washing water can be used as the degree of
contamination of laundry. In this case, the operating time and the
amount of water to be supplied in the wash and spin-drying steps
are controlled based on the degree of contamination of the washing
water.
[0034] Washing water-condition detector 40 is composed of optical
sensor 41 and electrode sensor 42 in the above-described washing
machine. Detector 40 can alternatively be composed of either one of
sensors 41 and 42 to detect the degree of contamination of washing
water. The turbidity and the electrical conductivity of washing
water can alternatively be measured by a sensor other than sensors
41 and 42.
[0035] Light-receiving element 44 of optical sensor 41 is
preferably shielded from external light. If, however, optical
sensor 41 is an infrared sensor, it is unnecessary to shield
light-receiving element 44, thereby simplifying the structure.
[0036] The washing water circulating through circulation tube 37
contains bubbles and sand particles. Bubbles, which are lighter
than water, gather at the top of circulation tube 37. Sand
particles, which are heavier than water, gather at the bottom of
circulation tube 37. For this reason, the detection accuracy can be
improved by locating light-emitting element 43 and light-receiving
element 44 substantially horizontally on both sides around the
center of circulation tube 37. Alternatively, however, the degree
of turbidity of washing water can be detected by locating elements
43 and 44 vertically, diagonally, or horizontally on one side of
circulation tube 37.
[0037] Similarly, electrodes 45a and 45b of electrode sensor 42 can
be located around the perpendicular center of circulation tube 37.
In this case, electrodes 45a and 45b are not severely affected by
bubbles and can detect the electrical conductivity with high
accuracy. Alternatively, the electrical conductivity of the washing
water can be detected by locating electrodes 45a and 45b either
vertically or diagonally on both sides of circulation tube 37.
[0038] When circulation pump 39 is driven, the washing water kept
in outer tank 24 is drawn into water intake opening 33, passes
through washing water-condition detector 40 and drain filter 34,
and is injected through discharge port 38 into inner tank 25. The
washing water removes stains from the laundry, and then is again
drawn into water intake opening 33. The washing water kept in outer
tank 24 is circulated in this manner to make the concentration of
contamination of the washing water more uniform. In other words,
the degree of contamination of the washing water detected by
washing water-condition detector 40 becomes substantially the same
as that of the washing water in outer tank 24. Thus, the provision
of washing water-condition detector 40 in circulation tube 37
allows the quick and accurate detection of the degree of
contamination of the washing water. In short, the degree of
contamination can be detected in the early stages of washing.
Furthermore, injecting the circulated washing water onto clothes
allows the clothes to be dampened immediately after the washing
step is started. The mechanical force of the washing water
injecting onto the clothes further improves the washing
efficiency.
[0039] With the above-described structure, the washing water is
forcibly circulated by circulation pump 39 regardless of the
rotation of inner tank 25, which is the agitating portion for
agitating clothes. Therefore, the washing water can be well
circulated even when inner tank 25 is rotated at low speed. In
addition, it is possible to set arbitrary conditions that are not
affected by the operation of the agitating portion, such as the
amount and timing of circulation of the washing water. This can
improve the accuracy of detecting the degree of contamination of
the washing water, without affecting the washing effect. It is also
possible to circulate a larger amount of washing water to prevent
washing water-condition detector 40 from being smeared with
stains.
[0040] Circulation pump 39 is also driven in a spin-drying step to
circulate less-stained washing water through washing
water-condition detector 40. The less-stained washing water removes
the detergent and stains from washing water-condition detector 40
deposited in the washing step. Thus, washing water-condition
detector 40 is prevented from deterioration in the performance.
[0041] Circulation tube 37 has only one discharge port 38 below
outer tank 24 in the above description. Alternatively, two or more
discharge ports 38 may be provided by dividing circulation tube 37.
In this case, the washing water can be injected into inner tank 25
at the same time through these discharge ports 38. Alternatively,
washing water may be injected through one of these discharge ports
38 that is formed between outer and inner tanks 24 and 25.
[0042] Circulation pump 39 is intermittently operated in the wash
and rinsing steps. When circulation pump 39 is in operation,
bubbles and stain particles are circulated together with the
washing water. Therefore, the degree of contamination is high,
causing large variations in the detection value. To provide stable
and accurate detection, washing water-condition detector 40 detects
the condition of the washing water while circulation pump 39 is in
the stopped state. This improves the accuracy of estimating the
degree of contamination. The detection value is not stabilized
immediately after circulation pump 39 is stopped due to the
influence of bubbles and other causes. Therefore, the detection is
performed when a predetermined time has passed after having stopped
circulation pump 39. Alternatively, it is possible to use, as the
detection value, a value obtained when the variation width of the
detected turbidity becomes equal to or lower than a predetermined
value, thereby providing high detection accuracy. Alternatively, a
plurality of detection values may be averaged to remove errors,
thereby further improving the detection accuracy. Alternatively,
washing water-condition detector 40 may perform measurement at, for
example, one second intervals, and may use only necessary
information.
[0043] Similar to optical sensor 41, electrode sensor 42 can
perform calculation while circulation pump 39 is in the stopped
state, thereby providing high detection accuracy. The detection of
turbidity by optical sensor 41 and the detection of electrical
conductivity by electrode sensor 42 may be performed either at the
same time, or separately according to their characteristics. When
the accuracy is sufficient, the degree of contamination of washing
water may be detected while circulation pump 39 is in operation to
estimate the degree of contamination of the laundry.
[0044] As described above, the circulation of the washing water
through circulation tube 37 is performed not by rotating inner tank
25 as the agitating portion, but by driving circulation pump 39.
This allows the circulation of the washing water to be stopped
without stopping the operation of the agitating portion. As a
result, high detection accuracy can be obtained while maintaining
the washing effect. The speed of rotation of circulation pump 39
can be changed with the progress of a wash or rinsing step so as to
achieve high detection accuracy while considering the penetration
of the washing water into the clothes or the degree of
bubbling.
[0045] The rotation of inner tank 25 as the agitating portion,
which stirs the washing water in outer tank 24, can affect the
detection of washing water-condition detector 40, possibly causing
detector errors. The detection errors, however, can be reduced by
synchronizing the operations of circulation pump 39 and drive motor
26 (the rotation of inner tank 25). In this case, controller 46
synchronizes the driving and stopping of circulation pump 39, and
the driving and stopping drive motor 26. Drive motor 26 is driven
in the forward direction (hereinafter, normal rotation) and the
backward direction (hereinafter, reverse rotation). As a result,
washing water-condition detector 40 performs detection under
certain conditions. For example, controller 46 alternately repeats
driving circulation pump 39 for one minute and then stopping it for
one minute. The two minutes is referred to as one step. Controller
46 normally rotates drive motor 26 for 30 seconds, and then
reversely rotates for 30 seconds. Controller 46 performs this
operation twice in one step, thereby synchronizing the operations
of circulation pump 39 and drive motor 26. The above-described way
of taking synchronization is one example; the drive time and the
stop time are not necessarily equal, or the normal rotation time
and the reverse rotation time are not necessarily equal. The speed
of rotation of circulation pump 39 may be changed along the way.
The way of taking synchronization may be changed during washing
step.
[0046] Assume that controller 46 stops the rotation of inner tank
25 by stopping drive motor 26 when a predetermined time has passed
after having stopped circulation pump 39. In this case, both
circulation pump 39 and drive motor 26 go into a stopped state.
Washing water-condition detector 40 performs detections at or
around this moment so as to reduce measurement errors. The effect
can be obtained by stopping drive motor 26 only for a short while
between normal rotation and reverse rotation.
[0047] Discharge port 38 of circulation tube 37 is provided such
that washing water is injected into inner tank 25 from between
outer and inner tanks 24 and 25 as shown in FIG. 2. As a result,
the circulating washing water hits the laundry such as clothes to
dampen it quickly, thereby improving the washing efficiency of the
washing machine.
[0048] When circulation pump 39 is rotated at or above a
predetermined speed, the washing water is injected into inner tank
25 and is circulated through outer and inner tanks 24 and 25 as
shown in "B" in FIG. 2. When, on the other hand, circulation pump
39 is rotated at a speed lower than the predetermined speed, the
washing water is circulated through outer tank 24 as shown in "D"
in FIG. 6. Thus, controlling the speed of rotation of circulation
pump 39 allows switching between the following two conditions
according to the need. In one of the conditions, the washing water
does not directly go into inner tank 25. In the other condition,
the washing water is injected into both inside and outside inner
tank 25. The following is a description of improving the accuracy
of detection of washing water-condition detector 40.
[0049] As soon as the washing machine is started, feed valve 30 is
opened to feed water, and the detergent in detergent inlet 31 is
fed into outer tank 24 together with the water. If circulation pump
39 is rotated at or above the predetermined speed at the feed water
step, washing water with a high detergent concentration is injected
from discharge port 38 into inner tank 25. If the washing water
with the high detergent concentration is absorbed in the clothes,
the washing water in outer tank 24 has a low detergent
concentration. The washing water immediately after water feed is
started contains detergent only. Washing water-condition detector
40 can detect the washing water in this condition to determine
whether the detergent is powder or liquid. The detection result can
be used as the initial value of the washing water before starting a
washing step. If, however, a large amount of the washing water in
this condition is injected into inner tank 25, it is impossible to
determine the type of the detergent or to use the detection result
as the initial value of the washing water. For this reason, while
water is being fed immediately after a washing step is started,
circulation pump 39 is rotated at a speed lower than the
predetermined speed. By doing so, the washing water is not injected
into inner tank 25 through discharge port 38, but is dropped to the
bottom of outer tank 24. This allows the determination of the type
of the detergent, and improves the accuracy of detecting the
initial condition of the washing water before starting a washing
step. Assume that the circulation of the washing water by
circulation pump 39 is stopped to prevent the washing water from
being injected against the clothes. In this case, the washing water
kept in washing water-condition detector 40 and the washing water
kept in outer tank 24 are not made uniform, thereby providing low
detection accuracy. To avoid this happening, as described above,
the washing water is dropped from discharge port 38 to the bottom
of outer tank 24 and is circulated within outer tank 24 to
accelerate the dissolution of the detergent. This makes the
concentration of the washing water uniform. Later, in the middle of
the washing step, the washing water can be injected against the
laundry to improve the washing effect and to accelerate the
dissolution of stains on the laundry into the washing water. As a
result, the amount of stains can be estimated in the early stages.
Thus, controlling the speed of rotation of circulation pump 39
provides a highly accurate determination of contamination using
single circulation pump 39 and circulation tube 37.
[0050] When the washing water is circulated only within outer tank
24, it is preferable that no washing water is injected into inner
tank 25. In this case, it does not matter even if the washing water
splashes or runs down along the outer wall surface of inner tank 25
and gets into inner tank 25 through the holes or gaps of inner tank
25. The detection accuracy can be improved at least by reducing the
amount of washing water to be injected into inner tank 25. In other
words, the detection accuracy can be improved at least by
preventing the washing water from entering inner tank 25 and by
circulating the washing water within outer tank 24. Thus, the
detection accuracy can be improved not only when the washing water
is not at all injected into inner tank 25. The detection accuracy
can also be improved, even if part of the washing water is injected
into inner tank 25, by injecting other part of the washing water
between outer and inner tanks 24 and 25 so as to be circulated
within outer tank 24.
[0051] It is not just immediately after water feed is started that
the effect is achieved when the washing water is not injected into
inner tank 25 or when the washing water is injected into both
inside and outside inner tank 25. For example, when a washing step
is started and the detergent creates a lot of bubbles, the bubbles
can be increased by injecting the washing water into inner tank 25.
The bubbling, on the other hand, can be suppressed by stopping the
washing water from being injected into inner tank 25. This prevents
a decrease in the detection accuracy due to the bubbles. As
described above, controlling the speed of rotation of circulation
pump 39 can switch the injection of the washing water without
installing additional components.
[0052] The water fed through feed-water tube 32 is supplied between
outer and inner tanks 24 and 25. Washing water-condition detector
40 is located lower than the lowermost portion in inner tank 25 as
shown in "A" in FIG. 1. Therefore, the fed water reaches washing
water-condition detector 40 before entering inner tank 25.
[0053] In a rinsing step, the water fed through feed-water tube 32
reaches washing water-condition detector 40 without coming into
contact with the laundry such as clothes containing stains and
detergent. Washing water-condition detector 40 detects water not
containing stains or detergent, and therefore, it is possible to
detect aging of detector 4 from the stains deposited thereon. The
detection result can be used to correct measurement results,
thereby maintaining the detection accuracy according to aging.
[0054] When water is fed in a washing step, the water fed through
feed-water tube 32 does not enter inner tank 25, but reaches
washing water-condition detector 40 as washing water containing the
detergent put in detergent inlet 31. This prevents the detergent
from being stuck or adhered to clothes. As a result, the washing
water that has reached washing water-condition detector 40 does not
contain the stains from the clothes, but contains only the
detergent dissolved therein. Detecting this condition can improve
the accuracy of determining whether the detergent is powder or
liquid. This improves the accuracy of the initial value of the
washing water in a washing step, thereby improving the accuracy of
detecting the degree of contamination of the washing water. This
result can be used to achieve efficient washing when the laundry is
not heavily dirty. For example, the user can select a short wash
time or reduce the amount of water to be fed.
[0055] As more and more water is fed, more and more washing water
containing the detergent enters inner tank 25. Feed-water tube 32
allows the washing water to be fed into between outer and inner
tanks 24 and 25. This causes a smaller amount of detergent to be
stuck or adhered to the clothes than in the case of feeding water
directly into inner tank 25. In addition, even after water is fed
into inner tank 25, the accuracy of the initial value of the
washing water is high in a washing step.
[0056] Driving circulation pump 39 can accelerate the dissolution
of the detergent and the dampening of the clothes with the washing
water. The detergent-containing washing water reaches washing
water-condition detector 40 before circulation pump 39 is driven.
As a result, the initial condition of the washing water can be
detected with high accuracy before the detergent creates
bubbles.
[0057] It would be preferable to start to rotate inner tank 25 as
the agitating portion in the early stages to improve the washing
efficiency of the washing machine. Starting to rotate inner tank 25
in the early stages, however, would cause the washing water to
create bubbles, which may deteriorate the detection accuracy of
washing water-condition detector 40. To avoid this, the
detergent-containing washing water is made to reach washing
water-condition detector 40 before starting to rotate inner tank
25. As a result, the initial condition of the washing water can be
detected with high accuracy before the washing water creates
bubbles.
[0058] The rotation of inner tank 25 as the agitating portion, on
the other hand, stirs the washing water kept in outer tank 24,
making the washing water create bubbles. Washing water-condition
detector 40, however, is located at some midpoint in circulation
tube 37 that is away from water intake opening 33, thereby being
prevented from facing inner tank 25. This prevents the rotation of
inner tank 25 from affecting the detection of washing
water-condition detector 40. Instead of being in some midpoint
diagonal to inner tank 25 as shown in FIG. 1, washing
water-condition detector 40 can be prevented from facing inner tank
25 by providing a partition wall between inner tank 25 and washing
water-condition detector 40.
[0059] In the above-described drum type washing machine, inner tank
25 has a substantially horizontal axis of rotation. A similar
effect can be obtained in a different type of washing machine
(pulsator washing machine) as shown in the sectional view of FIG.
7. In FIG. 7, like components are labeled with like reference
numerals with respect to FIGS. 1 to 6. In the washing machine in
FIG. 7, inner tank 25 has a vertical axis of rotation. Inner tank
25 has agitator 47 as an agitating portion at its bottom surface.
Feed-water tube 32 allows water to be fed between outer and inner
tanks 24 and 25. In the case where water is fed through feed-water
tube 32 directly into inner tank 25, circulation pump 39 can
circulate washing water through circulation tube 37, and washing
water-condition detector 40 can detect the condition of the washing
water. Note that washer-dryers provide the same effect during
washing as this washing machine.
[0060] FIG. 8 is a sectional view of another example of the washing
machine according to the first exemplary embodiment. This washing
machine differs from the above-described washing machine in that
circulation tube 37 includes switching valve 48, and that
circulation tube 37 is divided into inner tank circulation tube 49
and outer tank circulation tube 50. In the washing machine of FIG.
8, switching valve 48 switches between tubes 49 and 50. Immediately
after water feed is started, outer tank circulation tube 50 is
selected to prevent the washing water form directly entering inner
tank 25. In this case, it is possible to accurately detect the
initial condition of the washing water which contains only
detergent dissolved therein. Furthermore, it is unnecessary to
reduce the amount of the circulating washing water by reducing the
speed of rotation of circulation pump 39. Thus, the washing
efficiency improves with increasing speed of dissolving the
detergent into the washing water. This balances the detection
accuracy of washing water-condition detector 40 with the washing
efficiency of the washing machine.
[0061] The washing machine shown in FIG. 8 includes switching valve
48. Another example of the washing machine shown in the sectional
view of FIG. 9 includes circulation pump 139. Circulation pump 139
switches between output tubes depending on whether it is in the
normal rotation or the reverse rotation. Circulation pump 139
switches between tubes 49 and 50 to feed the washing water through
it, thereby providing the same effect as using switching valve
48.
INDUSTRIAL APPLICABILITY
[0062] As described hereinbefore, the washing machine of the
present invention detects the degree of contamination of washing
water with high accuracy, thereby performing control according to
the degree of contamination. This washing machine can be applied to
other types of washing machines to wash something other than
clothes.
REFERENCE MARKS IN THE DRAWINGS
[0063] 21 Cabinet [0064] 24 Outer tank [0065] 25 Inner tank [0066]
27 Door [0067] 30 Fed valve [0068] 30a Feed-water inlet [0069] 31
Detergent inlet [0070] 32 Feed-water tube [0071] 33 Opening [0072]
34 Drain filter [0073] 35 Drain valve [0074] 36 Drainage tube
[0075] 37 Circulation tube [0076] 39 Circulation pump [0077] 40
Washing water-condition detector [0078] 41 Optical sensor [0079] 42
Electrode sensor [0080] 43 Light-emitting element [0081] 44
Light-receiving element [0082] 45a,45b Electrodes [0083] 46
Controller [0084] 47 Agitator [0085] 48 Switching valve [0086] 49
Inner tank circulation tube [0087] 50 Outer tank circulation
tube
* * * * *