EP2281081B1

EP2281081B1 - Method and device for treating laundry in a washing machine or washing/drying machine or clothes dryer

Info

Publication number: EP2281081B1
Application number: EP08806864A
Authority: EP
Inventors: Costantino Mariotti; Mariano Funari; Giovanni Bombardieri
Original assignee: Indesit Co SpA
Current assignee: Whirlpool EMEA SpA
Priority date: 2008-04-30
Filing date: 2008-07-31
Publication date: 2011-12-14
Anticipated expiration: 2028-07-31
Also published as: RU2458194C1; RU2010148753A; PL2281081T3; ITTO20080327A1; EP2281081A1; ES2379166T3; WO2009133424A1; ATE537288T1

Abstract

The invention relates to a method for treating laundry loaded in a washing machine or washing/drying machine or clothes dryer. The laundry is subjected to a steam flow generated in the washing or washing/drying machine through evaporation means, and an alarm signal goes off in order to inform a user of the machine that the creases on the laundry have been sufficiently smoothed. After the alarm signal has gone off, the evaporation means are activated for at least a non- null time interval, thus generating additional steam and subjecting the laundry to a further steam flow following the alarm signal.

Description

The present invention relates to a method for treating laundry in a washing machine or washing/drying machine or clothes dryer.
In traditional washing machines, during the wash and spin cycles the wet laundry is subjected to centrifugal force exerted by the rotating drum, which causes formation of creases so that the clothes are extracted creased and must then be ironed.
In order to eliminate, or at least smooth these creases, washing machines are known, such as the one described in patent application EP 1507028 by LG ELECTRONICS INC., which carry out a crease smoothing step by supplying heat to the laundry within the washing machine itself.
In such machines, a steam flow is generated and directed against the laundry as it is turning in the drum; as known, steam will smooth out laundry creases, thus simplifying and speeding up the subsequent ironing process.
According to the teaching of patent application EP 1507028 , the crease smoothing step is subdivided into two distinct cycles: an initial steam cycle, lasting for a preset time (e.g. two minutes) as the drum is rotating, and a subsequent laundry cooling cycle taking place with no steam production as the drum is rotating.
At the end of the cooling cycle, the drum is stopped and the user is informed that the crease smoothing step has been completed by an appropriate sound or luminous alarm, so that the laundry can be removed.
This crease smoothing step is illustrated in Fig. 1, which clearly shows that steam is supplied to the laundry during the steam cycle (from time t_p1 to time t_p2), which is then stopped and followed by the cooling cycle (from time t_p2 to time t_p3), at the end of which (time t_p3) the alarm goes off.
The use of steam is also known in "refresh" cycles (provided by clothes dryers as well), wherein dry and creased laundry (e.g. items which have been used without however being dirty) are loaded into the washing machine to be refreshed.
Said cycles comprise a single operational step wherein the laundry is subjected to a steam flow in order to remove any smells and to smooth the creases.
In all cases, steam is applied to the laundry substantially at the end of all machine operations, which is signalled to the user by a luminous or sound alarm.
Despite steam-treated laundry has fewer creases and can be ironed more easily than laundry not subjected to said method, the Applicant has found that the effect of the steam cycle fades over time in which the laundry is left lying in the washing machine after the steam cycle is over.
Moreover, when steam is used for executing refresh cycles, it is important that the laundry is not left too long in the drum of the clothes dryer after the treatment, because otherwise the steam will condense and the laundry will get wet.
The object of the present invention is to provide an alternative method and an alternative laundry washing machine which allow to overcome the above-mentioned problems.
This object is achieved through a method for treating laundry and through a machine implementing said method, incorporating the features set out in the appended claims, which are intended as an integral part of the present description.
The present invention is based on the idea of an alarm going off at the end of an optimal duration of the steam cycle, while however continuing the latter even after the alarm has gone off.
This avoids the possibility of leaving the laundry for a long time in the machine without steam, thus preventing new creases from forming (since the laundry is left lying in the machine) or the laundry from getting wet due to steam condensing after a refresh treatment. In fact, as the user hears the alarm, he/she will go to the machine to unload the laundry, and the steam cycle will still be on or will have been off for a shorter time than in the case wherein the alarm goes off at the end of all machine operations.
Advantageously, the steam cycle goes on until the user stops it manually.
Alternatively, in order to avoid excessive energy consumption, the steam cycle ends when a predetermined time has elapsed after the alarm has gone off.
Further objects and advantages of the present invention will become apparent from the following description of an embodiment thereof as shown in the annexed drawings, which are supplied by way of non-limiting example, wherein:

Fig. 1 is a simplified diagram which defines the various instants of the crease smoothing step according to the prior art;
Fig. 2 is a simplified diagram which defines the various instants of the laundry treatment method according to the present invention;
Fig. 3 is a simplified diagram of a second embodiment of the present invention.

Fig. 1 illustrates the above-described crease smoothing cycle according to the prior art; without further repetitions, the alarm signal goes off at the end of the cooling cycle that follows the steam cycle.
With reference to Fig. 2, there is shown a simplified diagram which is useful to understand the method in accordance with the teachings of the present invention.
The following example refers to a washing machine wherein the laundry to be treated is placed inside a drum which is rotated by a motor within a wash tub.
The drum rotation and in general the operation of the various machine components are controlled by a control unit adapted to implement the method described below.
As shown, the laundry treatment method (e.g. used for smoothing creases) starts at time t₁, when steam is supplied into the tub of the washing machine for the purpose of smoothing the laundry loaded therein.
The crease smoothing process begins at time t₁ with a steam cycle 1, which goes on until time t₃.
During the steam cycle, the machine drum is preferably kept turning, more preferably in alternate directions.
Time t₂ corresponds to the instant when it is believed that the creases have been sufficiently smoothed.
The time interval between t₁ and t₂ thus corresponds to an optimal duration of the steam cycle; said duration may be preset in the washing machine during the assembly cycle of the machine itself, or it may be chosen by a user through suitable controls fitted on the machine.
Said optimal duration t₁-t₂ may for example be selected as a function of load, in particular of the type and/or quantity of laundry.
When t₂ is reached, an alarm signal 2 goes off which preferably lasts until time t₃; the alarm may be audible, visual or of any other kind suitable for drawing the user's attention.
The alarm may be continuous over time, or else goes off at regular time intervals, e.g. every 30 seconds.
Time t₃ is the moment when a machine stop signal is generated.
Said signal is preferably generated when the user acts upon an appropriate machine stop control.
In this case, therefore, the steam cycle will go on until the user stops it.
In order to reduce the energy consumption of the machine and to limit the length of the steam cycle, which might cause damage to the laundry (let us consider the case wherein the laundry is turned for hours in the drum), according to an advantageous solution the stop signal is generated automatically by the machine control unit when the time interval between t₂ and t₃ exceeds a predetermined value preset during the assembly cycle of the machine itself or included in a program selected by the user.
In this case, therefore, the steam cycle will continue after the alarm (t₂) for a predetermined time equal to T=t₃-t₂, unless it is stopped manually by the user.
In order to generate steam, the washing or washing/drying machine implementing the method according to the present invention is provided with evaporation means controlled by the machine control unit.
Said evaporation means may, for example, comprise a steam producing boiler in which water is evaporated and then delivered into the tub.
Alternatively, steam may be produced by the very same electric resistance that warms up the wash water in the tub, as described in patent application EP1275767 , to which reference is made herein.
The evaporation means therefore comprise the electric resistance that warms up the water in the tub.
Of course, the method according to the present invention may be subject to many changes without departing from the objects and protection scope thereof.
For example, for the purpose of further reducing energy consumption, it is possible to decrease the steam flow supplied into the tub after the alarm has gone off, as shown diagrammatically in Fig. 3.
In the example of Fig. 3, during the time interval t₁-t₂ the steam flow rate P1 delivered to the tub is substantially constant.
The corresponding quantity of steam Q₁ applied to the laundry during this time interval is that which is believed to be most appropriate for the steam cycle.
According to the embodiment of Fig. 3, at time t₂ the alarm is activated, while at the same time the steam flow rate is decreased to a value P₂ smaller than P₁; said flow rate is required for keeping the creases sufficiently smoothed and to prevent/reduce the formation of new creases.
It is also possible, as an alternative or in addition to steam reduction, to reduce the drum rotation speed after the alarm goes off.
After the alarm goes off it might even be possible to provide a series of rotation cycles alternated with time intervals during which the drum is kept stationary. In this case, the steam supply might even be suspended during the pauses between two rotation cycles, so long as said pauses and the interruption of steam supply are kept short.
A further variant, which is advantageous in that it reduces the time in which no steam is applied to the laundry before the latter is removed by the user, is that of quickly: discharging the steam immediately after the user has stopped the steam cycle.
In fact, washing and washing/drying machines are normally fitted with a safety device which will keep the load door of the machine locked if the temperature within the tub is high, e.g. due to the presence of residual steam.
In order to reduce the time in which the load door is kept locked, according to a variant of the invention the washing or washing/drying machine is provided with means for accelerating the discharge of the steam externally; said means may, for example, comprise a fan specially operated for this purpose, or an additional door preferably located on the rear side of the machine, which opens at the end of the steam cycle.
Notwithstanding the above embodiment examples refer to a method for smoothing creases in a laundry washing machine, it is apparent that the same method can also be used as a method for refreshing dry laundry (refresh cycle), e.g. in a clothes dryer.
In this case, the dry (or slightly damp) laundry is loaded into the drum of the machine (e.g. a clothes dryer) and subjected to a steam flow generated by the machine through evaporation means such as, for example, a boiler.
The machine then carries out a predetermined refresh cycle, at the end of which an alarm signal goes off in order to inform the user that the laundry can be removed from the machine.
In a clothes dryer, which has no wash tub but only a rotary drum, the treatment is carried out by supplying steam into the drum and to the laundry therein.
As aforementioned, according to the laundry treatment method (in this case, a refreshing method), the evaporation means are activated for at least a non-null time interval (t₂-t₃) after the alarm signal has gone off, thus generating additional steam and subjecting the laundry to a further steam flow following the alarm signal.
The refreshing method may also be subject to the very same variations previously described with reference to the crease smoothing method:

continuous steam supply until the user stops the treatment manually or for a predetermined time T,
reduction of the produced steam flow rate after the alarm goes off,
reduction of the drum rotation speed after the alarm goes off,
or use of a quick steam discharge system (this variant is also applicable to a clothes dryer, fitted with a safety door lock).

Claims

Method for treating laundry loaded in a washing machine or washing/drying machine or clothes dryer,
wherein the laundry is subjected to a steam flow generated in the machine through evaporation means, and
wherein an alarm signal goes off in order to inform a user of said machine that a predetermined treatment has been completed,
characterized in that
said evaporation means are activated for at least a non-null time interval (t₂-t₃) after the alarm signal has gone off, thus generating additional steam and subjecting the laundry to a further steam flow following the alarm signal.
Method according to claim 1, wherein the laundry is placed in a drum which is kept turning as steam is being generated.
Method according to claim 1 or 2, wherein said non-null time interval ends when a stop signal is generated.
Method according to claim 3, wherein the stop signal is generated by the user of the machine.
Method according to claim 3, wherein said time interval has a predetermined duration and wherein the stop signal is generated automatically by the machine.
Method according to any of the preceding claims, wherein said evaporation means are alternately activated and deactivated for a plurality of non-null time periods after the alarm signal has gone off.
Method according to any of the preceding claims, wherein the flow rate of the steam applied to the laundry is reduced after the alarm signal.
Method according to any of claims 2 to 7, wherein the drum is turned at a first speed before the alarm signal, and wherein the drum is turned at a second speed, which is slower than said first speed, after said alarm signal.
Method according to claim 8, when dependent on claim 6, wherein said drum is stopped when said evaporation means are deactivated.
Method according to any of claims 3 to 9, wherein the quantity of steam discharged outside the machine is increased after the stop signal.
Method according to claim 10, wherein a fan is turned on after the stop signal in order to discharge the steam externally.
Washing machine or washing/drying machine or clothes dryer comprising
at least one rotatable drum into which laundry is loaded,
evaporation means adapted to generate a steam flow to be applied to the laundry,
means adapted to generate an alarm signal,
a control unit adapted to control the rotation of said drum, said evaporation means and said alarm means,
characterized in that
said control unit is adapted to implement a method according to any of claims 1 to 11.
Machine according to claim 12, wherein said evaporation means comprise a boiler for water heating and evaporation.
Machine according to claim 12, wherein
the drum is rotatable inside a tub adapted to contain wash water, and
wherein said evaporation means comprise an electric resistance adapted to warm up water being present in the tub.
Machine according to one or more of claims 12 to 14, comprising a fan which can be controlled by said control unit in a manner such that the steam is discharged outside the machine in response to a machine stop signal.