U.S. patent application number 11/956395 was filed with the patent office on 2008-06-19 for method for controlling a washing machine.
This patent application is currently assigned to E.G.O. ELEKTRO-GERAETEBAU GMBH. Invention is credited to Rainer Muenzner, Kay Schmidt.
Application Number | 20080141465 11/956395 |
Document ID | / |
Family ID | 39271532 |
Filed Date | 2008-06-19 |
United States Patent
Application |
20080141465 |
Kind Code |
A1 |
Muenzner; Rainer ; et
al. |
June 19, 2008 |
METHOD FOR CONTROLLING A WASHING MACHINE
Abstract
A washing machine is constructed with a special control unit and
a conductance sensor in a washing liquid container for detecting a
water level including whether there the water is above or below a
given water level, and the presence of foam during a washing cycle.
The control unit controls the operation of a pump, as well as the
addition of fresh water, for eliminating excessive foam in the
washing liquid container and in the drum. It is also possible to
stop the pump from discharging this disturbing foam.
Inventors: |
Muenzner; Rainer;
(Schwarzenberg, DE) ; Schmidt; Kay;
(Graben-Neudorf, DE) |
Correspondence
Address: |
ALSTON & BIRD LLP
BANK OF AMERICA PLAZA, 101 SOUTH TRYON STREET, SUITE 4000
CHARLOTTE
NC
28280-4000
US
|
Assignee: |
E.G.O. ELEKTRO-GERAETEBAU
GMBH
Oberderdingen
DE
|
Family ID: |
39271532 |
Appl. No.: |
11/956395 |
Filed: |
December 14, 2007 |
Current U.S.
Class: |
8/158 |
Current CPC
Class: |
D06F 39/087 20130101;
D06F 33/00 20130101 |
Class at
Publication: |
8/158 |
International
Class: |
D06F 39/08 20060101
D06F039/08; D06F 33/02 20060101 D06F033/02 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 14, 2006 |
DE |
10 2006 060 256.0 |
Claims
1. A method for controlling operation of a washing machine, said
washing machine having a control unit, a washing liquid container
and a conductance sensor being located in a lower area of said
washing liquid container, comprising the steps of: using a
conductance sensor to measure a water level in said washing liquid
container; determining, by said control unit, said water level is
lower than a position of said conductance sensor; and stopping a
pump pumping out the water in said washing liquid container.
2. The method according to claim 1, wherein said pump is provided
for said emptying of said washing liquid container and said
stopping of said pump takes place within a few seconds delay after
the water level has been detected to be lower than said position of
said conductance sensor.
3. The method according to claim 2, wherein said delay results in a
water level further below said position of said conductance sensor
without resulting in an intake of air in said pump.
4. A method for controlling operation of a washing machine, said
washing machine having a control unit, a washing liquid container
and a conductance sensor being located in a lower area of said
washing liquid container, comprising the steps of: determining a
water level in said washing liquid container using said control
unit; determining using said control unit during a washing process
that said sensor is surrounded by foam; and adding fresh water into
said washing liquid container for diluting said foam.
5. The method according to claim 4, wherein sufficient fresh water
is added to ensure that during said washing process or a rotation
of said drum said conductance sensor is essentially surrounded by
water.
6. A method for controlling operation of a washing machine, said
washing machine having a control unit, a washing liquid container
and a conductance sensor located in a lower area of said washing
liquid container comprising the steps of: measuring values of said
conductance sensor by said control unit; determining a surface
tension of water in said washing liquid container by a detection of
an ionic concentration of said water; determining whether said
surface tension exceeds a threshold limit associated with the
ending of said washing cycle; and determining a rinsing process
based on said surface tension.
7. A method for controlling operation of a washing machine, said
washing machine having a control unit, a washing liquid container
and a conductance sensor being located in a lower area of said
washing liquid container, comprising the steps of: determining a
value measured by said conductance sensor by said control unit; and
adjusting a drying speed so that said conductance sensor is
surrounded by water.
8. The method according to claim 7, further comprising: using a
pump controlled by said control unit for emptying said water in
said washing liquid container, wherein said pump runs continuously
during said spin drying process.
9. The method according to claim 7, wherein said spin drying speed
is increased after a period of time when said conductance sensor is
determined to be no longer surrounded by said water.
10. The method according to claim 9, wherein said spin drying speed
is slowly increased until said conductance sensor is again
essentially surrounded by water.
11. The method according to claim 9, wherein said period of time is
a few minutes.
12. The method according to claim 11, wherein said value measured
by said conductance sensor is used by said control unit to control
said pumping operation.
13. The method according to claim 12, wherein on reaching a maximum
of said spin drying speed said pump is switched off when said
conductance sensor is no longer surrounded by said water and is
switched on again when said conductance sensor is surrounded by
said water.
14. The method according to claim 13, wherein between a change of
function at said conductance sensor and a switching on or off of
said pump there is a time interval of a few seconds.
15. A method for controlling operation of a washing machine, said
washing machine having a control unit, a washing liquid container
and a conductance sensor being located in a lower area of said
washing liquid container, comprising the steps of: detecting a
measured value of said conductance sensor; providing said measured
value to said control unit; and determining by said control unit
whether said conductance sensor is surrounded by water, foam, or
air, whereupon detection of said foam a drying speed of said drum
is reduced as a countermeasure for reduction of said foam.
16. The method according to claim 15, further comprising the step
of: establishing by said control unit using said conductance sensor
whether said foam has already been adequately reduced or no longer
surrounds said conductance sensor, wherein if said conductance
sensor is not surrounded or has been adequately reduced, said drum
is stopped.
17. The method according to claim 16, comprising the further step
of: detecting foam after said stopping of said drum; waiting for a
time of a few minutes; and introducing fresh water into said drum
for rinsing away said foam.
18. A method for controlling operation of a washing machine, said
washing machine having a control unit, a rotating drum controlled
by said control unit, a washing liquid container and a conductance
sensor being located in a lower area of said washing liquid
container, comprising the steps of: interrupting a washing or
rinsing process at a first time period of said washing machine
wherein rotation of said drum is stopped; measuring a first value
of said conductance sensor when said drum is not rotating and
supplying said first value to said control unit; resuming said
washing or rinsing process of said washing machine wherein said
drum is rotating; interrupting said washing or rinsing process at a
second time period wherein said drum of said washing machine is
stopped; and measuring a second value of said conductance sensor
when said drum is not rotating and supplying said second value to
said control unit.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is based on German Application No.
102006060256.0 filed on Dec. 14, 2006, of which the contents are
hereby incorporated by reference.
FIELD OF THE INVENTION
[0002] The invention relates to a method for controlling the
operation of a washing machine, where a conductance sensor is
placed in a washing liquid or powder container of the washing
machine.
BACKGROUND OF THE INVENTION
[0003] For controlling the operation of a washing machine it is for
example known from US 2006/0191496 A1 or EP 633 342 A1 to place a
conductance sensor in the interior thereof, for example in the
lower area of the washing liquid container. The measured values of
the conductance sensor are determined and evaluated by the washing
machine control unit. However the possibilities for further
processing or using these measured values as described therein are
limited.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] Embodiments of the invention are described hereinafter
relative to the attached diagrammatic drawings, wherein:
[0005] FIG. 1 illustrates a diagrammatic inner view of one
embodiment of an inventive washing machine; and
[0006] FIGS. 2 to 4 illustrate different graphs for representing
relationships between surfactant concentration, surface tension and
conductance.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0007] A problem addressed by the invention is to provide an
aforementioned method with which the functionality of a washing
process or operating process for the washing machine or the
evaluation of an aforementioned conductance sensor can be
improved.
[0008] One embodiment is a method having the features of claims 1,
3, 5, 6, 9 or 12. Advantageous and preferred embodiments of the
invention form the subject matter of the further claims and are
explained in greater detail hereinafter. It is in particular also
possible to combine several of the aspects according to the
invention. By express reference the wording of the claims is made
into part of the content of the description.
[0009] In a first basic embodiment of the invention, the
conductance sensor detects the water level and, if said water level
has dropped below the placing of the conductance sensor, an
emptying of the washing liquid container is stopped, i.e., in
particular, a pumping out with a pump is stopped. This makes it
possible to prevent an idle running of the pump when the washing
liquid container has been completely pumped empty, which on the one
hand avoids unnecessary power consumption and on the other hand, in
those phases where the drum does not rotate, prevents unpleasant,
audible noises.
[0010] Particularly if an aforementioned pump is provided for
emptying the washing liquid container, it is advantageous for the
switching off of the pump to take place with a few seconds delay
after the water level has dropped below the conductance sensor.
Such a delay can in particular be matched to the fact that with a
normal pumping capacity the water level is admittedly lowered
somewhat further below the conductance sensor, but an idle running
of the pump or an intake of air at the same is avoided. This
ensures that the pump is operated close to an optimum range, i.e.,
for emptying of the washing liquid container or a lowering of the
water level to just above the pump. However, this is not essential,
because the pump can also be switched off if the water level is
below it. What is important is to establish where the water level
is relative to the pump in order to avoid any noise.
[0011] According to another basic embodiment of the invention, the
conductance sensor is constructed to detect whether it is
surrounded by foam during the washing process. This can not only be
detected by the conductance sensor, but also in cooperation with
the washing machine control unit or conductance sensor control
unit. Fresh water is added as a countermeasure for the reduction or
elimination of foam. Thus, the foam or liquid is at least diluted
and as far as possible the foam removed. A detection of the foam on
the conductance sensor is consequently possible with a high
reliability level within the scope of the invention. Particularly
in the case of capacitive conductance sensors, measured values for
said foam state at the conductance sensor are between those for air
and those for the case where said sensor is surrounded by
water.
[0012] It is advantageously also possible as a countermeasure when
foam is present, to add fresh water in such a quantity or for so
long as to ensure that during the washing process or during the
drum rotation, the conductance sensor is essentially or
particularly advantageously constantly surrounded by water. This
avoids the negative effects of excessive foam during washing.
[0013] According to another basic embodiment of the invention by
means of the conductance sensor, it is possible to detect the
surface tension of the washing liquid in the drum or in the liquid
by determining the ionic concentration in the washing liquid. On
the basis of this, it is possible to determine whether a specific
surface tension is exceeded and a rinsing of the washing or laundry
can be ended. In this way, it is possible to establish whether the
detergent has been adequately rinsed out of the laundry. Thus, for
example, as a function of the detected ionic concentration, the
length or number of rinsing processes can be adapted accordingly.
This is, in particular, continued until the ionic concentration or
surface tension has exceeded a given, predetermined value and
consequently the laundry is considered as being adequately
rinsed.
[0014] According to another basic embodiment of the invention, it
is possible during the spin drying process, particularly with the
pump constantly running, to increase the spin drying speed only
until the conductance sensor is largely uninterruptedly or even
constantly surrounded by water. This means that initially slow spin
drying speeds are used, because then with the laundry still very
wet, sufficient water is ejected from the said laundry, so that the
water level is above the conductance sensor. Since as a rule the
pumping capacity is limited or the pump always runs at its maximum
capacity, it serves little purpose to spin dry the laundry even
faster and eject even more water if this cannot be conveyed away in
good time and sufficiently rapidly by the pump. Moreover, the
laundry in the drum is constantly rotated through the water at the
bottom of the washing liquid container and becomes wet again, which
is to be avoided.
[0015] It is advantageously additionally possible to only increase
the spin drying speed when the conductance sensor after a long
period of time, particularly a few minutes during which it was
constantly or essentially surrounded by water, is no longer or is
no longer essentially surrounded by said water. This means that
then the pump can keep up with the water being removed from the
laundry and can remove it and, as a result, the laundry can be spin
dried with ever greater intensity and speed. With particular
preference the spin drying speed can be slowly increased until the
conductance sensor is again essentially or constantly surrounded by
water. This can be repeated several times and the spin drying speed
can be ever further increased. Due to this slow rise in the spin
drying speed, an unnecessarily early or rapid spinning of the drum
with the associated power consumption and bearing wear can be
avoided.
[0016] Advantageously by means of the conductance sensor and its
measured values, a control of the pump operation is possible. It is
possible on reaching a maximum spin drying speed to switch off said
pump again if the conductance sensor is no longer or essentially no
longer surrounded by water. It is advantageously only switched on
again when the conductance sensor is constantly or essentially
surrounded by water. Thus, it is possible to ensure that the pump
is not continuously running at a maximum spin drying speed.
Admittedly, the above-described idle running of the pump with an
intake of air is not critical with respect to the noise burden
during spin drying, especially at high speeds, because it is much
less noisy than the spin drying operation. However, an unnecessary
power consumption and wear to the pump can be reduced.
[0017] It is particularly advantageously possible between a state
change at the conductance sensor, i.e., a state when it is
essentially surrounded by water and a state when it is essentially
exposed and a switching on and off of the pump, to wait for a time
interval of a few seconds, as described hereinbefore. This time
interval can for example be in the range 5 to 30 seconds,
particularly 10 to 20 seconds. As described hereinbefore, this
brief time interval can also be provided to ensure that when the
pump continues to run, further water is pumped out until just prior
to pump idling. When the pump is stationary and the water rises
there is a wait until the water level is just above the conductance
sensor, but has not yet reached the laundry again. This reduces the
pump operating frequency.
[0018] According to another basic development of the invention, as
stated hereinbefore, it is possible to determine on the conductance
sensor whether it is surrounded by water, foam or air. Thus, during
a spin drying process, the drum speed can be reduced if foam is
detected at the conductance sensor. The reduction of the drum speed
is a countermeasure for reducing foam formation, because the foam
is then impacted less or no longer by the drum passing through it.
A speed reduction can for example be 10 to 30%. In particular, the
speed can be reduced slowly or in stages until the conductance
sensor is no longer surrounded by foam. In certain circumstances it
is even possible to completely stop the drum if the conductance
sensor is still surrounded by foam. It is particularly
advantageously possible, after stopping the drum, to wait for a few
minutes, for example up to 5 minutes. If the conductance sensor is
still surrounded by foam or detects foam, it is possible to use the
further countermeasure of introducing fresh water for rinsing the
foam away. After introducing fresh water for a certain time, or in
a certain quantity, a check is again made to establish whether the
conductance sensor is surrounded by foam. If this is the case,
further fresh water can be added until the foam is eliminated. As a
further test measure, the pump can be started. If it then idles,
which can be easily established by measuring the power consumption
of the pump and this lasts for a few seconds to a few minutes,
there is in fact still foam at the conductance sensor.
[0019] According to a further basic embodiment of the invention, it
is possible in a method for operating an aforementioned conductance
sensor, or during the measurement of the conductivity in the
washing liquid container or liquid, to briefly interrupt the
washing or rinsing process, particularly also a spin drying
process, in order to carry out the conductance measurement.
Particularly in the case of an interruption or for the conductance
measurement, the drum can be stopped and then the conductance is
measured with the drum stationary. This avoids the liquid being
impacted by the drum movement in the washing liquid container so as
to produce foam. It is also possible to calm the water in the
washing liquid container, which also permits a better and more
reliable conductance sensor evaluation.
[0020] It is also possible within the scope of the invention that
one of two prescribed safety circuits for the heater can be
avoided, because it is possible to determine with the conductance
sensor within the framework of the aforementioned water level
measurement whether the heater is in the water. This permits a
simpler washing machine construction.
[0021] These and further features can be gathered from the claims,
description and drawings and individual features, individually or
in the form of subcombinations, can be implemented in an embodiment
of the invention and in other fields and can represent
advantageous, independently protectable constructions for which
protection is claimed here. The subdivision of the application into
individual sections and the subheadings in no way restrict the
general validity of the statements made thereunder.
[0022] FIG. 1 shows a washing machine according to an embodiment of
the invention and having a drum 13 containing washing or laundry
14. Drum 13 is driven by motor 15 with a belt drive. A washing
liquid or powder container is located below and surrounds the drum
13 and has an outflow 18. Said outflow 18 leads to a pump 20, which
conveys water out of the washing liquid container 17, via an
outflow hose 21 from the washing machine 11. Into the washing
liquid container 17 projects a heater 23 in order to heat the water
or liquor therein. FIG. 1 does not show an inflow for fresh water
and for the detergent-mixed water. However, in the same way as the
washing machine is described in this connection, the inflow can be
constructed as is known in the prior art.
[0023] In the embodiment shown, a conductance sensor 24 projects
into the washing liquid container 17 close to the heater 23, as is
for example known from US 2006/0191496 A1. The conductance sensor
24 effectively defines a broken line-represented level 25 marking
the height up to which it can detect water or foam and further
reference will be made thereto hereinafter. The conductance sensor
24 is also connected to a control unit 26, which can also be
connected to the pump 20 and/or heater 23, particularly for the
control thereof or for evaluating the operating state thereof.
Motor 15 can also be connected to control unit 26 and both can be
controlled by the latter and additionally or alternatively for the
detection of its operating state, as described hereinbefore.
[0024] As stated hereinbefore, the conductance sensor 24 can, for
example, establish whether water or foam is located above or below
the level 25 or whether it is immersed in water. This can in
particular be used in impacting the above-described pumping
operation. It is also pointed out here that the conductance sensor
24 with level 25 is well below the lowermost point of drum 13.
Thus, a water level can rise well above the conductance sensor 24
or level 25 without reaching the drum 13 and the washing 14 therein
and making the latter wet again. Appropriate consideration must be
taken of this height difference in connection with the
above-described, hysteresis curve-like possibility so that when the
water rises above level 25, the pump 20 is only switched on after a
certain time, but always in sufficient time before the water
reaches drum 13. The same applies regarding the lowering of the
water below level 25 before pump 20 runs dry during pumping
away.
[0025] As the different possible methods have already been
described, there is no need to go into detail in this connection
here, but are made even clearer in conjunction with FIG. 1.
[0026] FIG. 2 shows how it is possible to measure the surface
tension of the liquid in which is located the content of drum 13,
particularly the laundry 14, based on the surfactant concentration.
There is a fixed relationship between the same and in particular
control unit 26 can draw the indicated conclusions therefrom.
[0027] In a similar way the conductance and surfactant
concentration are in a fixed mutual relationship, as shown in FIG.
3.
[0028] Finally, in accordance with FIG. 4, the conductance can be
related to the surface tension in the liquor in drum 13 or washing
liquid container 17. Then for the different surfactants and
different surfactant concentration ranges, virtually linear
relationships are obtained, namely ranges 1 to 4 in FIG. 4. If the
surfactant concentration range is known to be, for example a very
high surfactant concentration during the washing process,
conclusions regarding the surfactant concentrations can be drawn
from the liquid conductivity on the basis of the conductance.
However, if the surfactant concentration is low, for example when
rinsing laundry 14 in drum 13, the conductance can also be
established from the fixed relationship. As the control unit 26
advantageously forms the complete control for the washing machine
11, it is aware of the given program sequence and therefore also
knows whether a washing process or a rinsing process is taking
place. The precise nature of the surfactant used need not
necessarily be known, because on the basis of a starting value and
with a random surfactant the concentration change can be detected.
This is adequate for the aforementioned optimization of the washing
and rinsing processes. In particular, different curves according to
FIG. 4 can be stored in control unit 26 and used for detection
purposes.
* * * * *