EP2171147B1 - Method for controlling the generation of suds in a washing machine and a washing machine suitable therefor - Google Patents

Description

The invention relates to a method for controlling the generation of foam, in particular in a treatment of laundry with foam, in a program-controlled washing machine and a particularly suitable for performing this method washing machine.

In known washing processes, the laundry to be washed is treated only with an amount of water or wash liquor, also referred to as a "liquor", which is sufficient for the laundry to be washed to be saturated with water and a minimum free liquor, generally 2 to 3 liters, a mass transfer between the heater for heating the wash liquor and the laundry allows. The free liquor corresponds to the remainder of the wash liquor which is not bound by the wash and thus exists as a liquid. The appropriate dimensioning of the water quantity or liquor is ensured by suitable methods for regulating the water level in the drum and the adjustment of the amount of water to the suction capacity of the laundry. The free liquor results after deduction of the amount of water bound in the laundry of the amount of water filled in the washing machine. Cotton fabric binds about 200% of its own weight, so that a load of 6 kg of cotton fabric binds about 12 liters of water.

The energy consumption of a washing machine is essentially determined by the energy required for the heating of the water. A reduction in the amount of water in the washing machine would therefore be desirable, in particular a reduction in the amount of free liquor. However, the free fleet must ensure the heat transfer from the heater to the laundry. A reduction of the fleet and thus a reduction in energy consumption are thus difficult to achieve.

An alternative to this known washing process is the washing with foam, which can be produced by introducing mechanical energy into a wax liquor. The foam takes care of the heating and cleaning of laundry to be cleaned.

In order to ensure sufficient energy transport from a heater in a washing machine in the laundry, a sufficient foam development is necessary. Due to the lower heat capacity of foam compared to the Heat capacity of a wash liquor would otherwise risk overheating the heater. However, if the foaming process is too strong, there is a risk of the foam escaping from the washing machine, in particular its dispenser tray. In addition, it should be noted that the development of foam depends on a large number of parameters. Some of the parameters can be influenced by a program-controlled washing machine by a corresponding design of the corresponding washing programs (for example, temperature, amount of water, speed of the drum). Type and amount of laundry and detergents (surfactants and other substances) and water hardness and degree of contamination of the laundry, however, are not influenced by a washing machine and are subject to unpredictable fluctuations from application to application.

In the DE 43 34 969 A1 a device for the destruction of detergent foam is described in a washing machine with a rotatable drum in a tub having a device for generating hot air, which is introduced through a feed line in the tub wall between the tub and the drum.

According to the disclosure of DE 41 04 151 A1 Foam which occurs undesirably in a washing machine is destroyed by switching on a heating device. In order to destroy the foam in the wider vicinity of the heater, the drum is rotated slowly, so that more foam passes to the heater and is destroyed there by supplying heat.

In addition, methods for removing foam in a tub of a drum type washing machine are known from DE 102 34 472 A1 as well as the DE 198 46 248 A1 known.

The DE 102 34 472 A1 discloses a method for removing foam in a tub of an electronically controlled drum washing machine as a result of a program step, which is provided for dewatering the tub, with a Laugenablaufsystem arranged at the bottom of the tub with a drain pump and with a sensor for determining the height of the tub located in the tub Liquid. The course of the sensor signal (P) is recorded during the operation of the drain pump, contains a gradient Ap _n / .DELTA.t _n compared to Ap _n-1 / .DELTA.t _n-1, indicating the presence of foam, whereupon one of the Gradient-matched foam treatment measure is initiated.

The EP 0 268 155 A2 describes a washing machine with a device for preventing foaming. For this purpose, a washing machine with so-called. Foam brake is proposed, wherein the speed of a laundry drum drive motor is reduced until the foam limit has been adjusted back to a certain low level, which is then consistently below.

In the EP 0 278 239 A1 Excessive foaming in the main wash, observed during the heating of wash liquor in the tub, is eliminated by adding a limited amount of cold water and / or by temporarily turning off the liquor heater.

The object of the invention is to provide a method for controlling the generation of foam, in particular in a treatment of laundry with foam, in a program-controlled washing machine and a particularly suitable for performing this method washing machine.

According to the invention, these objects are achieved by a method having the features of patent claim 1 and by a washing machine having the features of patent claim 12. Advantageous embodiments of the invention are listed in the respective dependent claims. Preferred embodiments of the method correspond to preferred embodiments of the washing machine and vice versa, even if it is not indicated in detail in each case.

1. a) Detektion eines im Laugenbehälter und/oder in der Trommel befindlichen Schaums, und
2. b) Einstellung und/oder Beibehaltung eines von c₁ bis c₂ vorgegebenen Bereiches für die Konzentration des Schaums,

umfasst, wobei die Detektion (a) des Schaums mittels eines oder mehrerer Sensoren, die einen hydrostatischen Druck p im Laugenbehälter und/oder in der Trommel verfolgen, geschieht, und wobei ein gemessener hydrostatischer Druck p mit einem vorgegebenen unteren Wert p₁ für den hydrostatischen Druck und einem vorgegebenen oberen Wert p₂ für den hydrostatischen Druck verglichen und für den Fall $$\mathrm{p}<{\mathrm{p}}_{\mathrm{1}}$$

die Drehzahl U der Trommel (2) heraufgesetzt, und für den Fall $$\mathrm{p}>{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="imgf0001.png"\; state="\{\{state\}\}">p</figure-callout>}}_2$$

die Drehzahl U der Trommel (2) herabgesetzt wird.The invention thus relates to a method for controlling the generation of foam in a treatment of laundry with foam from an aqueous wash liquor in a program-controlled washing machine with a liquor drain system arranged at the bottom of a tub with a drain pump, a rotating drum and a heater, the method steps

1. a) detection of a foam located in the tub and / or in the drum, and
2. b) adjustment and / or maintenance of a foam concentration range specified by c ₁ to c ₂ ,

wherein the detection (a) of the foam is monitored by means of one or more sensors which track a hydrostatic pressure p in the tub and / or in the drum, and wherein a measured hydrostatic pressure p is compared with a predetermined lower value p ₁ for the hydrostatic pressure and a predetermined upper value p ₂ for the hydrostatic pressure and for the case $$\mathrm{p}<{\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="imgf0001.png"\; state="\{\{state\}\}">p</figure-callout>}}_{\mathrm{1}}$$

the speed U of the drum (2) increased, and in the case $$\mathrm{p}>{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="imgf0001.png"\; state="\{\{state\}\}">p</figure-callout>}}_2$$

the speed U of the drum (2) is reduced.

During the process according to the invention, the heating device heats the foam and / or the wash liquor.

The detection of foam can thus be carried out, for example, via a conductance measurement with two electrodes in the lower region of the tub.

In addition, a sensor used in any case in a known washing machine, referred to as a water level regulator, may, for example, be used as the sensor. In the measurement of the hydrostatic pressure is advantageous that a significant increase in pressure can be measured if, during rotation of the drum, in particular during spinning, a gap between the drum and the tub is completely filled with foam.

• a1) die Drehzahl U der Trommel (2) um eine vorgegebene Drehzahldifferenz ΔU₁ herabgesetzt,
• a2) nach einem vorgegebenen Zeitraum Δt der Druck p erneut gemessen und festgestellt, ob die Beziehung p ≤ p₂ erfüllt ist, und
• a3) für den Fall, dass immer noch p > p₂ gilt, die Drehzahl U um ΔU_n, wobei n eine natürliche Zahl ≥ 2 ist, herabgesetzt, und die Schritte a2) und a3) werden (n-1)-mal wiederholt, bis ein vorgegebener Wert U_min erreicht oder unterschritten ist,

In the case of p> p ₂ , it is preferable

• a1) the speed U of the drum (2) is reduced by a predetermined speed difference ΔU ₁ ,
• a2) the pressure p is measured again after a predetermined period Δt and it is determined whether the relationship p ≦ p _{2 is} satisfied, and
• a3) in the event that p> p _{2 still} holds, the rotational speed U is reduced by ΔU _n , where n is a natural number ≥ 2, and the steps a2) and a3) are repeated (n-1) times until a predetermined value U _{min is} reached or fallen below,

• b1) die Drehzahl U der Trommel (2) um eine vorgegebene Drehzahldifferenz ΔU₁ heraufgesetzt,
• b2) nach einem vorgegebenen Zeitraum Δt der Druck p erneut gemessen und festgestellt, ob die Beziehung p ≥ p₁ erfüllt ist, und
• b3) für den Fall, dass immer noch p < p₁ gilt, die Drehzahl U um ΔU_m, wobei m eine natürliche Zahl ≥ 2 ist, heraufgesetzt, und die Schritte b2) und b3) werden (m-1)-mal wiederholt, bis ein vorgegebener Wert U_max erreicht oder überschritten ist.

In the case where p <p ₁ , it is preferable

• b1) the speed U of the drum (2) is increased by a predetermined speed difference ΔU ₁ ,
• b2) the pressure p is measured again after a predetermined period Δt and it is determined whether the relationship p ≥ p _{1 is} satisfied, and
• b3) in the event that p <p _{1 still} holds, the rotational speed U is increased by ΔU _m , where m is a natural number ≥ 2, and steps b2) and b3) are repeated (m-1) times until a predetermined value U _{max is} reached or exceeded.

Here, m and n may be the same or different. In addition, the speed differences ΔU _n and ΔU _m may be the same or different.

An increase in the speed of the drum causes more water or foam is ejected from the laundry. This increases the water level at a bottom of the tub. As a result, enhancement of the interaction between this water and the rotating drum occurs. In addition, due to the greater speed of the drum more intense mechanical interaction also leads to an intensification of the development of foam.

On the other hand, a reduction in the rotational speed of the drum results in the undersaturated portion of the laundry, that is, in a laundry item having less water than it could bind to fully saturate the laundry with water at the instantaneous speed of the drum absorbed the laundry items and thus the amount of water in the gap between the drum and the tub is reduced. In addition, the reduced mechanical interaction reduces the generation of foam.

• a4) die Drehung der Trommel beendet;
• a5) Wasser eingefüllt;
• a6) die Trommel in einen Reversierbetrieb umgeschaltet, und/oder
• a7) es erfolgt eine Anzeige, dass eine zu hohe oder falsche Waschmitteldosierung vorliegt.

If, in the method according to the invention, the rotational speed U has reached or fallen below the predetermined value U _min , it is preferred

• a4) stops the rotation of the drum;
• a5) water filled;
• a6) the drum is switched to a reversing operation, and / or
• a7) There is an indication that the dosage of detergent is too high or incorrect.

• b4) die Drehung der Trommel beendet;
• b5) Wasser eingefüllt; und/oder
• b6) es erfolgt eine Anzeige, dass eine zu geringe Waschmitteldosierung vorliegt.

Has in the inventive method, the speed U reaches the predetermined value U _max or exceeded, is preferably

• b4) stops the rotation of the drum;
• b5) water filled; and or
• b6) there is an indication that the dosage of detergent is too low.

It is further preferred in the last two preferred embodiments that in step a5) or b5) water is introduced in an amount which allows a normal washing process with a wash liquor without foam and this washing process is carried out.

The display of too low (b6) or too high or incorrect detergent dosing (a7) is preferably carried out acoustically and / or optically.

If, therefore, the desired area for the foam development can not be reached despite utilizing an available adjustment range for the rotational speed of the drum, then a signal can be output to a control device of the washing machine, which initiates further steps. Is it e.g. despite a maximum rotational speed of the drum (also referred to as "maximum spin rate") not possible to generate sufficient foam, the washing process can be continued after the addition of water to the usual level as a conventional washing process. For the user of the washing machine, an audible or visual signal may be issued about the lack of or insufficient detergent addition.

If, on the other hand, the foam development is so strong that, despite a minimum speed of the drum, the concentration of foam (also referred to as "foam level") is too high (eg if the user has added too much or a non-foam detergent for hand wash or for wool), Thus, the washing process can also be continued as a conventional washing process after addition of water to the usual level. In this case, an acoustic or visual signal can be output to the user of the washing machine on the wrong or too high detergent addition.

After carrying out step a4) and / or a6) for a predetermined period of time, the inventive method can be carried out again.

Thus, for example, a strong turning of the drum (spin) can be switched off and switched over to a normal reversing operation of the drum for a predetermined time. As a result, the absorption of the water in the foam state is supported by the laundry items and thus effectively reduces the amount of foam. When reversing, a drain pump can also be switched on to the amount in the tub and available for generating foam to reduce to washing liquor. Following this lathering of the foam, an attempt can be made to switch back to spinning and, if a desired foam concentration is set, to carry out a foam-based washing process.

In carrying out the method according to the invention, the drum rotates, preferably at a speed U in the range of 200 to 600, preferably 230 to 500 revolutions per minute. Here, the lower limit is generally given by the resonance speed of the vibration system and the upper limit by the maximum possible spin number.

Alternatively, or in addition to the already described method may U _to an evaluation of a target / actual difference in rotational speed - U _is at a rotation of the drum for detecting (a) can be used of the foam. In the detection of foam on an evaluation of the target / actual speed difference, in particular during spin, use is made of the fact that the foam can brake a rotating drum, whereby there is a difference between the target and the actual speed , In this case, the association between a specific foam concentration and the target / actual difference is generally stored in a data memory of the drum washing machine.

A desired concentration c _{v of} the foam, which is predetermined in the range of c ₁ to c ₂ , can be adjusted and / or maintained by a continuous change in the rotational speed U of the drum.

Preferably, the concentration c ₁ corresponds to the hydrostatic pressure p ₁ and the concentration c _{2 to} the hydrostatic pressure p ₂ .

The invention also relates to a washing machine with a program control for controlling the program flow, a rotatably mounted in a tub drum, one at the bottom of the tub arranged Laugenablaufsystem with a drain pump, a drive motor for the drum, a heater, a sensor for determining a quantity of in the tub liquid or a foam, and switching means for rotating and stopping the drum, wherein the switching means and the sensor can perform the inventive method described herein.

When the foaming control method of the present invention has achieved the setting and maintenance of a desired concentration of foam, the treatment of a laundry load with foam can be carried out.

This can be achieved by a method for treating laundry with an aqueous wash liquor in a program-controlled washing machine with a liquor drain system arranged at the bottom of a tub with a drain pump, a heater, a sensor for determining the amount of a liquid in the tub or a foam, wherein a sensor signal is followed during the process, and a drum with a certain, relative to a loading amount of laundry comparatively small amount of water done.

The invention enables the stable operation of a washing machine in a foam using washing process. A desirable foaming is promoted while preventing foaming. The invention also ensures sufficient cooling of the heating device of a washing machine and can prevent the switching on of the heater when there is insufficient foaming.

An embodiment of a washing machine according to the invention for carrying out the method of the invention shows FIG. 1 , Other embodiments are conceivable. The embodiment will be explained below.

FIG. 1 is a schematic representation of the relevant parts of a washing machine in which the described method can be performed. The washing machine of the FIG. 1 embodiment shown has a tub 1, in which a drum 2 rotatably mounted and operated by a drive motor 14. With regard to the ergonomics in dealing with such washing machines, the axis of rotation 3 of the drum 2 from the horizontal by a small angle (eg 13 °) directed forwardly upwards, so that you have easier access and insight into the interior of the drum 2. By this arrangement, in conjunction with specially shaped Wäschemitnehmern 4 and 5 Schöpfeinrichtungen for the wash liquor 6 on the inner surface of the drum shell also an intensification of the flooding of the laundry 7 with wash liquor and foam and a reduction of the free liquor is achieved.

The foam formed in a washing process with foam should in particular fill a space between the drum 2 and the tub 1.

The washing machine has a liquor inlet system comprising a water connection fitting for the domestic water network 8, an electrically controllable valve 9 and a supply line 10 to the tub 1, which may optionally also be guided via a Waschmitteleinspüleinrichtung ("Einspülschale") 11, from which the feed water detergent portions can transport in the tub 1. In addition, in the tub 1, a heater 13. The valve 9 as well as the heater 13 can be controlled by a control device ("program control") 12 in response to a program flowchart. The control device 13 receives in particular the values measured by a sensor 15 for the hydrostatic pressure p in the tub 1, which are used to change or maintain a rotational speed of the drum 2. For this purpose, the drive motor 14 is controlled via the control device 12.

Claims (12)

1. Method of controlling the foam generation in treatment of laundry by foam from an aqueous washing solution in a program-controlled washing machine with a solution drain system, which is arranged at the base of a solution container (1), with a solution pump, a rotating drum (2) and a heating device (13), comprising the steps of

   a) detection of a foam present in the solution container (1) and/or in the drum (2) and

   b) setting and/or maintaining a range, which is preset from c₁ to c₂, for the concentration of the foam, wherein

   the detection (a) of the foam is carried out by means of one or more sensors (15) tracking a hydrostatic pressure p in the solution container (1) and/or in the drum (2), characterised in that a measured hydrostatic pressure p is compared with a predetermined lower value p₁ for the hydrostatic pressure and a predetermined upper value p₂ for the hydrostatic pressure, and for the case $$\mathrm{p}<{\mathrm{p}}_{\mathrm{1}}$$

   

   
   the rotational speed U of the drum (2) is increased and for the case $$\mathrm{p}>{\mathrm{p}}_{\mathrm{2}}$$

   

   
   the rotational speed U of the drum (2) is decreased,
   and that the heating device (13) heats the foam and/or the washing solution.
2. Method according to claim 1, characterised in that for the case $$\mathrm{p}>{\mathrm{p}}_{\mathrm{2}}$$

   

   a1) the rotational speed U of the drum (2) is decreased by a predetermined rotational speed difference ΔU₁,

   a2) after a predetermined period of time Δt the pressure p is measured again and it is established whether the equation p ≤ p₂ is fulfilled and

   a3) for the case that p > p₂ still applies, the rotational speed U is decreased by ΔU_n, wherein n is an integral number ≥ 2, and the steps a2) and a3) are repeated (n-1) times until a predetermined value U_min is reached or fallen below,

   and for the case $$\mathrm{p}<{\mathrm{p}}_{\mathrm{1}}$$

   

   b1) the rotational speed U of the drum (2) is increased by a predetermined rotational speed difference ΔU₁,

   b2) after a predetermined period of time Δt the pressure p is measured again and it is established whether the equation p ≥ p₂ is fulfilled and

   b3) for the case that p < p₁ still applies, the rotational speed U is increased by ΔU_m, wherein m is an integral number ≥ 2, and the steps b2) and b3) are repeated (m-1) times until a predetermined value U_max is reached or exceeded.
3. Method according to claim 2, characterised in that for the case of the rotational speed U having reached or fallen below the predetermined value U_min,

   a4) rotation of the drum is ended;

   a5) water is added;

   a6) the drum (2) is switched over to reversing operation; and/or

   a7) an indication is given that a too-high or false washing agent dosage is present.
4. Method according to claim 2, characterised in that for the case of the rotational speed U having reached or exceeded the predetermined value U_max,

   b4) rotation of the drum is ended;

   b5) water is added; and/or

   b6) an indication is given that a too-small washing agent dosage is present.
5. Method according to claim 3 or 4, characterised in that for the case a5) or b5) water is added in a quantity which makes possible a normal washing method with a washing solution without foam and this washing method is carried out.
6. Method according to claim 3 or 4, characterised in that the indication is given acoustically and/or optically.
7. Method according to claim 3, characterised in that after carrying out step a4) and a6) the method according to any one of claims 1 to 4 is carried out again for a predetermined period of time.
8. Method according to any one of claims 1 to 7, characterised in that the drum (2) rotates at a rotational speed U in the range of 200 to 600 revolutions per minute.
9. Method according to any one of the preceding claims, characterised in that an evaluation of a target/actual rotational speed difference U_target - U_actual is used, during rotation of the drum (2), for detection (a) of the foam.
10. Method according to any one of the preceding claims, characterised in that a concentration c_v of the foam in the range of c₁ to c₂ is predetermined and is set and/or maintained by a continuous change in the rotational speed U of the drum (2).
11. Method according to claim 1, characterised in that the concentration c₁ corresponds with the hydrostatic pressure p₁ and the concentration c₂ corresponds with the hydrostatic pressure p₂.
12. Washing machine with a program control (12) for controlling the program sequence, a drum (2) rotatably mounted in a solution container (1), a solution drain system, which is arranged at the base of the solution container (1), with a solution pump, a drive motor (14) for the drum, a heating device (13), a sensor (15) for determining a quantity of a liquid or foam present in the solution container (1), and switching means (9, 12, 14) for rotating and stopping the drum, characterised in that the switching means (9, 12, 14) and the sensor (15) are arranged for carrying out a method for controlling foam generation according to any one of the preceding claims.

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