Title:
Method for washing shrinkable textiles and a washing machine for carrying out said method
Kind Code:
A1


Abstract:
A method for washing shrinkable textiles in a program-controlled washing machine consisting in washing textiles in a rotatably mounted washing drum according to a process corresponding to textile requirements with a water flow and possibly washing agents, wherein a starting and operating time of a drum driving motor are predefined. A washing machine for carrying out said method is also disclosed. At the beginning of the washing process, the motor operates with a staring time rate which is greater than a possible staring time and which decreases step by step or continuously during the process in order to reduce a mechanical energy applied to the textile according to the shrinkability thereof which strongly increases along with the increase of the washing process time. In such a way, the textile is pre-wetted with an optimal water quantity or soapy solution without producing the excessive textile shrinkage.



Inventors:
Czyzewski, Gundula (Berlin, DE)
Ruediger, Oliver (Berlin, DE)
Application Number:
11/886939
Publication Date:
01/15/2009
Filing Date:
01/09/2006
Assignee:
BSH Bosch und Siemens Hausgeraete GmbH (Munchen, DE)
Primary Class:
Other Classes:
68/12.17
International Classes:
D06F35/00; D06F37/06; D06F37/30
View Patent Images:



Primary Examiner:
KLING, CHARLES
Attorney, Agent or Firm:
BSH Home Appliances Corporation (NEW BERN, NC, US)
Claims:
1. 1-20. (canceled)

21. A method for washing a batch of laundry made of shrinkable textiles in a program-controlled washing machine having a motor driving a rotatably mounted washing drum, the method comprising: moving the batch of laundry with a washing liquid for wetting and flushing by operating the motor with predefined power-on times and power-off times, wherein the power-on time ratio of the motor, which is defined by the quotient of the power-on time and the sum of the power-on time and the power-off time, is reduced during the progress of the washing process step by step or continuously in accordance with the increase in the sensitivity to shrinkage.

22. The method as claimed in claim 21, further comprising baffles with an evacuation facility on the inside shell of the washing drum for evacuating the water from the lower area of a washing tub, the washing drum rotating the evacuated water raining down over the batch of washing when the evacuation facility is situated above the batch of laundry.

23. The method as claimed in claim 21, wherein the washing drum is rotated exclusively in one direction during the washing method.

24. The method as claimed in claim 22, wherein the washing drum is rotated in the direction of effectiveness of the evacuation facility.

25. The method as claimed in claim 21, wherein the washing drum is rotated in alternating directions during the washing method.

26. The method as claimed in claim 22, wherein the washing drum is rotated in the direction of effectiveness of the evacuation facility with a power-on time ratio for this direction which is greater than the power-on time ratio for the opposite direction.

27. The method as claimed in claim 21, wherein the motor is operated during a phase at the beginning of the washing process with a power-on time ratio greater than 12%.

28. The method as claimed in claim 27, wherein the motor is operated during a phase at the end of the washing process with a power-on time ratio less than 5%.

29. The method as claimed in claim 21, wherein the drum is rotated at a rotational speed of 15 to 35 rpm.

30. The method as claimed in claim 21, wherein the drive phases of the motor follow at an interval of 10 to 60 seconds.

31. A program-controlled washing machine for washing a batch of laundry made of shrinkable textiles comprising: a washing tub; a washing drum rotatably mounted within the washing tub and being driven by a motor; and a program-control unit including facilities for controlling the motor and for controlling the course of the rotational speed of the washing drum in respect of the value of the rotational speed, the direction of rotation, the power-on time and the power-off time of the motor, wherein the facilities for the step-by-step or continuous reduction of the power-on time ratio are implemented in accordance with the increase in the sensitivity to shrinkage during the washing process by controlling the power-on time and power-off time.

32. The washing machine as claimed in claim 31, further comprising baffles on the inside shell of the washing drum, the baffles being equipped with an evacuation facility evacuating the water from the lower area of the washing tub and raining the evacuated water when the evacuation facility is situated above the batch of washing.

33. The washing machine as claimed in claim 31, wherein the rotation of the washing drum takes place exclusively in one direction of rotation during the washing process.

34. The washing machine as claimed in claim 32, wherein the direction of rotation of the washing drum corresponds to the direction of effectiveness of the evacuation facility.

35. The washing machine as claimed in claim 31, wherein the rotation of the washing drum takes place with alternating directions of rotation during the washing process.

36. The washing machine as claimed in claim 32, wherein the rotation of the washing drum takes place in the direction of effectiveness of the evacuation facility with a power-on time ratio for this direction which is greater than the power-on time ratio for the opposite direction.

37. The washing machine as claimed in one of claims 31, wherein the facilities for controlling the motor are implemented during a phase at the beginning of the washing process with a power-on time ratio greater than 12%.

38. The washing machine as claimed in claim 37, wherein the facilities for controlling the motor are implemented during a phase at the end of the washing process with a power-on time ratio less than 5%.

39. The washing machine as claimed in claim 31, wherein the drum is rotated at a rotational speed of between about 15 to 35 rpm.

40. The washing machine as claimed in claim 31, wherein drive phases of the motor have an interval of 10 to 60 seconds.

Description:

The invention relates to a method for washing a batch of laundry made of shrinkable textiles in a program-controlled washing machine, which is moved in a rotatably mounted washing drum while water and if applicable washing agent flushes through it during handling in a process section that is adapted to meet the requirements of the textiles, whereby the power-on and power-off time of a motor driving the washing drum is predefined, and a washing machine for carrying out said method.

A method for washing wool, which is a shrinkable type of textile, is known from DE 37 03 860 A1. With regard to this method, the washing drum is driven during successive motion and resting phases by a motor which accelerates the washing drum during the extremely short motion phases by way of a ramp to a rotational speed of 45 rpm, whereby the direction of rotation of the washing drum changes with successive motion phases. The duration of the respective resting phases is a multiple of the duration of the motion phases.

The mechanical load on the textile and thus the shrinkage of said textile should be reduced as a result of the extremely short motion phases and the special start-up of the motor. The disadvantage of such a method is the fact that the textiles are not completely wetted with water or washing liquid even after multiple motion phases and are not sufficiently flushed through for the purposes of cleaning.

With regard to a method known from EP 475 462 A1 for washing a batch of shrinkable washing, a washing drum of a washing machine is driven in a fine reversing motion mode. The washing drum is equipped with evacuation facilities beneath so-called baffles to improve the moisture penetration of the washing, which are implemented such that water is preferably taken up in an evacuation direction of rotation by the baffles and the baffles are emptied in the opposite direction of rotation. The rotation rhythm of the washing drum is adapted to the evacuation facility, whereby the washing drum is operated in the fine motion mode with a power-on time of 30%. EP 475 462 A1 discloses the use of different rotation rhythms in which the washing drum is driven in the evacuation direction of rotation and in the opposite direction of rotation with the same or with different percentage power-on time ratios.

A further washing machine and methods adapted to different textile types for washing the washing are known from US 2003/0061840 A1. Such a washing machine has a washing drum comprising two halves which can rotate with respect to one another. The washing methods are divided into a plurality of process sections in which the washing drum is operated with different power-on times, depending on a chosen program. Within such process sections, the drum halves are driven to rotate either in the same direction or in opposite directions. One of the disclosed methods is suitable for washing shrinkable textiles, whereby in a main washing process the drum halves are driven in the same direction in a first phase with a short power-on time and in a subsequent phase with a very short power-on time. There follows a further phase in which the drum halves are driven in opposite directions with a longer power-on time compared with the preceding phase.

The object of the invention is therefore to set down a method and a washing machine for carrying out the method which, during a washing process adapted in such a way as to meet the requirements of shrinkable textiles, wets and flushes the textiles at an early stage with the optimum quantity of water or washing liquid and thus optimizes the washing process for shrinkable textiles.

According to the invention, the method described in the introduction is implemented such that the ratio of the power-on time to the possible power-on time of the motor becomes smaller step by step or continuously during the process section.

It has namely been shown that the sensitivity to shrinkage of the textiles increases significantly principally with the duration of handling. It is therefore particularly advantageous to move the textile relatively vigorously at the beginning of the washing process, as a result of which a rapid wetting and good flushing of the textile with water or washing liquid can be achieved without causing excessive shrinking of the textile. During the further course of the washing process the sensitivity to shrinkage increases as a result of the increasing duration of action and if applicable as a result of a rising handling temperature of the water or the washing liquid. Therefore, advantageously with regard to the inventive method the degree of motion of the textile is reduced as the duration of handling increases corresponding to the increase in the sensitivity to shrinkage. Such a reduction in the motion of the textiles is achieved by reducing the ratio of the power-on time to the possible power-on time of the motor. This means that the duration of the respective power-on times of the motor is reduced and/or the duration of the respective power-off times is extended during the progress of the washing process.

In one embodiment of the invention, the rapid wetting of the textiles is advantageously supported inasmuch as while the washing drum, on the inside of whose shell is arranged a facility for evacuating the water from the lower area of a washing tub, is rotating the evacuated water rains down over the washing when the evacuation facility is situated in any position higher than the batch of laundry. The textiles are thus wetted not only by the unabsorbed washing liquid but they are acted on from all sides by water or washing liquid.

According to the developments of the invention, during the process section the washing drum is rotated exclusively in one direction or in alternating directions of rotation, as a result of which a rearrangement of the textiles is advantageously achieved within the batch of laundry in order that all the items of washing are wetted evenly.

It has been shown that when the washing drum rotates at a relatively low rotational speed of to 25 rpm for example a rearrangement of the washing is achieved particularly successfully if the washing drum is moved exclusively in one direction of rotation since at such a drum speed the textiles in the washing drum are lifted only slightly from the baffles arranged around the drum shell. When the direction of rotation remains the same, the items of washing are thus gradually subjected to further movement and rearranged, whereas a rotation of the drum in the opposite direction at such a rotation speed would move the items of washing back to the original location.

Compared with this, rotation of the washing drum in alternating directions of rotation at a rotational speed of 25 to 35 rpm for example is more favorable for a rapid rearrangement of the items of washing within the batch of laundry since at such rotational speeds the items of washing are lifted further by the baffles and drop back from the drum shell to the base of the washing drum, as a result of which a random distribution of washing is achieved and the batch of laundry is thus redistributed particularly quickly.

In a further advantageous embodiment of the method, the washing drum is rotated in the direction of effectiveness of the evacuation facility. As a result, the evacuation facility is optimally filled with water or washing liquid when the washing drum rotates and when the evacuation facility is situated above the batch of laundry the quantity of water taken up rains down from the evacuation facility onto the textiles.

In an advantageous development of the inventive method, during operation of the washing drum which has an evacuation facility with an optimum effectiveness for one direction of rotation the washing drum is rotated in the direction of effectiveness of the evacuation facility with a power-on time ratio for this direction which is greater than the power-on time ratio for the opposite direction. As a result of such a development, it is also possible when operating the washing drum with alternating directions of rotation to clearly support a rapid wetting of the batch of laundry through optimum utilization of the evacuation facility.

The rapid wetting and flushing of the textiles is additionally promoted in a particularly advantageous manner as a result of the fact that at the beginning of the washing process the power-on time ratio is greater than 12%. Through this embodiment, a lack of movement at the beginning of the washing process is avoided and an intensive penetration of the textile with water or washing liquid is achieved. The high level of motion of the textiles additionally causes a vigorous washing mechanism, which is particularly advantageous for cleaning the textile.

In order to avoid shrinkage of the textiles, in a further embodiment of the invention a power-on time ratio of less than 5% is chosen at the end of the washing process. It has been shown that particularly at the end of the washing process the sensitivity to shrinkage has increased so significantly as a result of the preceding and still continuing soaking of the textile that in the case of such a slight movement of the textiles excessive shrinkage of said textiles is effectively avoided. Since the textiles are handled with a high level of motion at the beginning of the washing process, in spite of the slight motion at the end of the washing process the absolute washing mechanism required for the cleaning or the required mechanical energy is guaranteed and an optimum cleaning is achieved with little shrinkage of the textiles.

It has also been shown that the drum rotation, in accordance with the design features of the washing tub and/or of the washing drum, with a rotational speed of 15 to 35 rpm is particularly advantageous for all possible embodiments of the method according to the invention. The precise rotational speed value can still be optimized depending on the geometry, function of the baffles and the preferred direction of rotation.

Correspondingly, in accordance with the design features of the washing tub and/or the washing drum the drum motion has proved particularly suitable with a pause of 10 to 60 seconds. As a result, the washing solution has the opportunity to act sufficiently intensively on the textiles.

The inventive design of the method and of the washing machine for carrying out said method will be described in detail in the following with reference to two exemplary embodiments for a motion sequence of a washing drum during a washing process. In the drawings

FIG. 1 shows a schematic cross-section through a washing tub with a washing drum,

FIG. 2 shows a qualitative graph of the sensitivity to shrinkage as a function of the duration of action on a textile during the washing process,

FIG. 3 shows a qualitative graph of the power-on time ratio as a function of the washing process duration,

FIG. 4 shows an inventive unidirectional motion sequence of the washing drum with reference to a diagram, and

FIG. 5 shows an inventive motion section for the washing drum with alternating directions of rotation with reference to a diagram.

A washing machine has a washing drum 1 shown in FIG. 1 in a rotatably mounted washing tub 2 and a motor which is not shown that drives the washing drum 1. On the inside of the shell of the washing drum 1 are fixed three washing baffles 3 which when the washing drum 1 rotates cause the items of washing from the batch 6 to be lifted from the base of the washing drum 1 and fall down again on account of gravity after being lifted. The washing mechanism required for the cleaning is thus applied to the items of washing. The degree of motion or of the washing mechanism applied to the washing items depends on the geometric dimensions of the washing drum 1 and of the baffles 3 and also on the rotational speed of the washing drum 1. The drum diameter of the washing machine in the preferred embodiment is 50 cm. Other drum diameters are also possible, whereby the drum rotational speed in particular must then be adapted accordingly for the drum diameter in question.

FIG. 2 shows a qualitative graph of the sensitivity to shrinkage SE of a textile, wool for example, as a function of the duration of action t during a washing process. In this situation, the duration of action t or the duration t of a washing process is plotted on the x-axis of the diagram and the sensitivity to shrinkage SE is plotted on the y-axis. The sensitivity to shrinkage SE specifies the degree to which the linear expansions of the item of washing change during handling of said item. In this situation, the sensitivity to shrinkage SE is specified as a ratio of the current linear expansion to the linear expansion of the item of washing prior to handling of said item expressed as a percentage.

In addition to the duration of action, the shrinkage of the textiles is influenced by the application of mechanical energy, for example in the form of textile motion. The parameters for the rotational speed of the washing drum 1 and the power-on time of the motor, which significantly influence the textile motion, therefore need to be matched to the sensitivity to shrinkage SE of the textiles. In addition to the textile motion, the shrinkage of the textile is also influenced by the temperature of the handling medium.

As shown in FIG. 2, the sensitivity to shrinkage SE is still relatively slight at the beginning of the washing process because the individual fibers have not yet swollen greatly as a result of the low action time. At the beginning of the washing process the textile which is otherwise extremely sensitive to shrinkage can thus also be moved more vigorously without causing an excessive shrinkage of the textile as a result of this motion.

The washing machine therefore has a program-control unit with facilities for controlling the motor and for controlling the course of the drum rotational speed in accordance with FIG. 4 or 5.

Provided that the washing drum 1 according to FIG. 4 is operated in only one direction of rotation, the motor is successively switched on during phase A for a period T_e of 12 seconds and switched off for a period T_a of 48 seconds, whereby the motor is controlled in such a manner that the washing drum 1 rotates at a rotational speed of 22 rpm during the power-on phases. The power-on time ratio ED during phase A is thus given by the formula ED=T_e/(T_e+T_a) as 20%.

Corresponding to the increase in the sensitivity to shrinkage ED represented in FIG. 2, with regard to the method according to FIG. 4 the power-on time of the motor T_e is reduced during phase B to 7.2 seconds (and to 1.8 seconds during phase C) and the power-off time T_a is accordingly extended to 52.8 seconds (and to 58.2 seconds during phase C). A power-on time ratio ED of 12% thus results for phase B and correspondingly a power-on time ratio of 3% for phase C. When the method is designed in this manner, this has the effect of reducing the application of mechanical energy into the textile as the sensitivity to shrinkage SE increases and of simultaneously maintaining the overall mechanical energy required for cleaning the textile. For example, with regard to washing methods for shrinkable textiles known from the prior art the washing drum is moved during the washing process with a constant power-on time ratio ED of 12%. The overall mechanical energy acting on the textile resulting in this situation is approximately as great as in the case of the embodiment according to the invention.

The change in the power-on time ratio ED during the washing process with regard to the preferred embodiment according to FIG. 4 is represented in the diagram according to FIG. 3 (solid function line). In alternative embodiments the ratio of the power-on time ED during the period t of the washing process can also be continuously reduced according to the broken line in FIG. 3.

Furthermore, the washing drum 1 has washing baffles 3 shown in FIG. 1, which are equipped with evacuation facilities 4 and which have holes 5 on their ridge sections, through which water evacuated from the lower section of the washing tub 2 rains over the batch of laundry 6 when the baffles 3, such as the baffle 3.1 in the illustration, reach a position above the batch of laundry 6 as a result of rotation of the washing drum 1 in the direction of the arrow 7.

In the preferred embodiment the washing drum 1 rotates exclusively in the direction of the arrow 7 so that the effectiveness of the evacuation facility is utilized to the optimum and the batch of laundry 6 is acted on from all sides with water or washing liquid. A rapid wetting and flushing of the textiles in the batch of laundry 6 is advantageously supported by this means.

According to the second embodiment, illustrated in FIG. 5, the washing drum 1 rotates in alternating directions at a rotational speed of +33 or −33 rpm. In this situation, in phase A the power-on time T_e1 of the motor at 15 seconds for the rotation of the washing drum 1 in the direction of the arrow 7 shown in FIG. 1 or in the direction of effectiveness of the evacuation facility 4 is longer than the power-on time T_e2 at 9 seconds for the rotation of the washing drum 1 in the opposite direction. During phase A, the power-off times are T_a1 45 seconds and T_a2 51 seconds. The power-on time ratio ED_< > of the motor for one direction of rotation is calculated according to the formula ED_< >=T_e< >/(T_e< >+T_a< >). The power-on ratio ED_1 of the motor for the rotation of the washing drum 1 in the direction of effectiveness of the evacuation facility 4 at 25% is thus greater than the power-on time ratio ED_2 in the opposite direction of rotation at 15%. Through such a choice of the power-on time ratios ED_1 and ED_2 it is possible to effectively utilize the effectiveness of the evacuation facility 4 in spite of the washing drum operating in alternating directions of rotation. The power-on and power-off times T_e1, T_a1, T_e2 and T_a2 are chosen such in the second embodiment that the mean power-on time ratio relating to the entire phase A is 20% as in the first embodiment.

The power-on and power-off times T_e1, T_a1, T_e2 and T_a2 for the motor with regard to the method according to FIG. 5 are summarized in the following Table 1:

TABLE 1
Phase APhase BPhase C
T_e115 seconds9seconds2.25
T_a145 seconds51seconds57.75
T_e2 9 seconds5.4seconds1.35
T_a251 seconds54.6seconds58.65
ED_125%15%3.75%
ED_215%9%2.25%
mean ED20%12%   3%

With regard to the inventive method, the power-on and power-off times T_e and T_a for the motor and the rotational speeds of the washing drum 1 are not restricted to the numerical values specified for the two embodiments but they can be varied to take into consideration the requirements of the textiles to be handled and the geometric dimensions of the washing drum and of the baffles 3 within the framework of the claimed ranges.