EP2217752B1 - Method and device for determining the optimal rotational speed of a drum of a laundry treatment device - Google Patents

Abstract

A method for determining a target rotational speed below an application rotational speed of a washing drum of a laundry treatment device having a drive and a vibrating system, wherein a dependence of a mechanical effect on items to be washed located in the washing drum on the respective nominal speed of the washing drum is used to ascertain the target rotational speed at which the mechanical effect is at the greatest. The mechanical effect at a respective target rotational speed is ascertained by measuring vibrating system movements of the vibrating system which exhibit greater frequency than the respective target rotational speed. The rotational speed at which the maximum vibrating system movement was measured is selected for carrying out the washing care procedure. The advantage of such a method is that the washing mechanics can be increased, thus improving the cleaning efficiency.

Description

The present invention relates to a method for determining a target speed below the application speed of a laundry drum, and a method for treating laundry using said method. Furthermore, the invention relates to a laundry treatment device which is equipped with a control element for carrying out the method according to the invention.

Washing and / or rinsing methods for automatic full automatic washing machines are already known in the prior art, in which the laundry drum is temporarily driven at varying speeds and directions of rotation during the washing and rinsing process in order to improve the washing effect. Such a procedure is over EP 0 618 323 A1 known. In this method, the laundry is to absorb water during the washing or rinsing operation at a speed well below the so-called application speed, at which the laundry is pressed by the centrifugal force to the drum wall. Due to this low speed the best possible flooding of the laundry should be achieved. The absorbed water should then be driven out of the laundry during operation at a speed significantly above the application speed again. This process is also known as wash-spin.

There are also laundry drums equipped with a scooping device. If such a scooping device is present, the speed and the direction of rotation are chosen such that the scooping device additionally supports the water absorption of the laundry. Thus, a good flooding of the laundry is achieved in this known method. A weakness of this process has an effect especially on large laundry loads. In fact, only a small washing mechanism is exerted on the laundry. When operating the laundry drum at speeds well below the application speed, the laundry performs a so-called rolling motion. The washing mechanism, consisting of compression and friction between the individual items to be washed is in the above method of EP 0 618 323 A1 significantly reduced during operation at speeds well below the application speed. When driving the laundry drum above the application speed, they are even completely missing, since the individual pieces of laundry wash firmly against the laundry drum wall.

Based on the aforementioned method has already been tried in the prior art, by preselecting certain different speeds, to increase the washing mechanics. An improved washing mechanism is particularly desirable for less sensitive laundry, otherwise too low a cleaning effect is achieved and no optimal washing result can be achieved.

In the DE 103 26 551 A1 Therefore, it is proposed to drive the laundry drum in at least one phase of intensive Waschgutdurchflutung and in at least one phase of high washing mechanics within the washing and / or rinsing process. These phases follow each other at least once during the washing and / or rinsing process. In the phase of intensive Waschgutdurchflutung the laundry drum is accelerated in one direction to a speed well above the application speed and in the other direction to a second speed well below the application speed. In the phase of high washing mechanics, the laundry drum is accelerated in both directions of rotation at speeds at which the individual items to be washed are strongly compressed and rub against one another. However, a method is not disclosed with which the optimum rotational speeds for the phases mentioned are determined for a respective washing program, a respective type of laundry and a respective loading quantity.

The DE 196 19 603 A1 Proposes to counter different loading amounts and the resulting different levels of Waschmechanikeinwirkungen at a fixed speed, characterized in that the speed is increased and decreased alternately and in response to the respective position of the driver. Here, however, there is still the problem that the speed change of different loads is independent.

The DE 102 17 009 C1 discloses a washing method in which a lower and an upper value for the drum speeds are set as a function of the loading and the drum is operated at different speeds.

The object of the present invention was to provide a method with which for each load and any washing program each optimal speed for the greatest possible washing mechanics can be determined and used.

• i) Antreiben der Wäschetrommel bei mindestens zwei unterschiedlichen Soll-Drehzahlen (n1 bis nx) unterhalb der Anlegedrehzahl für jeweils einen vorbestimmten Zeitraum (Δtn),
• ii) Messen eines Schwingsystembewegungswertes (s1 bis sx) bei jeder Soll-Drehzahl (n1 bis nx),
• iii) Vergleichen der Werte (s1 bis sx) untereinander, Bestimmen des höchsten Wertes (s) und Bestimmen derjenigen Soll-Drehzahl (n), die dem höchsten Schwingsystembewegungswert (s) zugeordnet ist.

This object is achieved by a method for determining a desired rotational speed (n) below an application speed of a laundry drum of a laundry treatment device with a drive and a vibration system, wherein a dependence of a respective mechanical action on a laundry present in the laundry drum of the respective target speed ( n) the laundry drum is used to determine the desired speed (s) at which the mechanical action is greatest, characterized by the following steps :

• i) driving the laundry drum at at least two different desired rotational speeds (n1 to nx) below the application speed for a respective predetermined period of time (Δtn),
• ii) measuring a vibration system motion value (s1 to sx) at each target speed (n1 to nx),
• iii) comparing the values (s1 to sx) with each other, determining the highest value (s) and determining the target speed (n) associated with the highest vibration system motion value (s).

During a conventional washing and / or rinsing process, the laundry drum, usually reversing, is operated at a so-called washing speed, which is about 55 min ^-1 for conventional washing machines. This speed is determined once during the device development empirically and set in the wash program. If now the laundry drum loaded with laundry, possibly wetted and operated at the washing speed, it should come to a certain mechanical effect.

The term laundry for the purposes of the present invention includes on the one hand textiles, especially laundry, but also generally all objects that can be treated in a conventional washing machine.

The term "washing mechanics" or "mechanical action" refers to the forces acting on the laundry when the laundry drum is moved. In particular, this is understood to mean a process in which the laundry items by s the drivers arranged in the laundry drum are taken and lifted and, once they have reached such a high point by the rotation of the drum that they are no longer held by the drivers, fall down again. The impact of the falling laundry items on underlying laundry items or the surface of the wash liquor has a good cleaning effect and is similar to a Walk. The speed at which the laundry items are exposed to the largest washing mechanism described above is the speed determined in the method of the invention.

As already mentioned, a laundry drum is operated during operation at a predetermined target speed (about 55 min ^-1 ). However, the actual speed varies depending on the type and amount of the load. In addition, the laundry case generated during the rotation of the laundry drum causes not inconsiderable deflections on the spring-mounted oscillating system.

The vibration system of a washing machine is understood to mean the drum, the associated tub as well as the springs and dampers on which the tub is suspended. The strength of the washing mechanism thus correlates with the strength of the oscillating system movement.

Surprisingly, it has been found that it is possible to measure the oscillatory system movements at target speeds below the application speed so accurately that conclusions can be drawn on the washing mechanism. By measuring the oscillating system movement of the laundry care process, usually during washing or during rinsing, with suitable sensors at different desired speeds n1-nx within a range which is below the application speed, for the respective load and the respective wash program the optimum washing speed is determined and, if necessary, redefined accordingly in each program run.

The method according to the invention thus preferably comprises the additional step of moving the drum at the previously determined setpoint speed n at which the greatest possible mechanical effect on the laundry is achieved. Thus, the present invention also provides a laundry treatment process with which Laundry may be washed, dried or otherwise treated under the greatest possible mechanical effect.

For the above-mentioned inventive method, at least two target rotational speeds are predetermined, preferably at least three (n1, n2 and n3), even more preferably at least four (n1, n2, n3 and n4). The predetermined desired speeds should be distributed over a reasonable range, which is for conventional washing machines in the range of 20 to 80 min ^-1 , always taking care that the relevant for the inventive process target speeds are below the respective application speed , Predetermined target speeds may, for example, be selected from the following: 20 min ^-1 , 25 min ^-1 , 30 min ^-1 , 35 min ^-1 , 40 min ^-1 , 45 min ^-1 , 50 min ^-1 , 55 min ^{- 1} , 60 min ^-1 , 65 min ^-1 , 70 min ^-1 , 75 min ^-1 and 80 min ^-1 .

In order to be able to fully exploit the possible range of target rotational speeds below the application speed, it can also be provided in the method according to the invention to first determine the application speed for all items to be washed at a respective load. This can be done by conventional methods or estimated on the basis of loading and empirical values.

As the highest predetermined target speed value for the oscillation system movement measurement, one is selected which is slightly below the application speed.

In order to determine the desired target rotational speed sought, the drum loaded with the laundry to be treated is thus operated at a first nominal rotational speed n1 for a predetermined period Δtn. During this period or within this period, the oscillating system movement is measured for a further predetermined period Δts using sensors associated with the oscillating system. From this measurement, which can also consist of several measuring points or a continuous measurement, as described below, a vibration system movement value s1 for the first setpoint rotational speed n1 is determined and assigned. Subsequently, the drum is operated at a second desired speed n2 and in turn assigned a vibration system movement value s2. These steps are performed until the laundry drum with all previously selected different target speeds n1-nx was operated and the oscillation movement values s1-sx assigned to these target rotational speeds were determined.

In the next step, the values s1-sx are compared, and the highest value for s is determined. This value is assigned to a target rotational speed n, which thus represents the optimum target rotational speed for the respective load for the greatest possible mechanical effect on the laundry. At this target speed then the laundry drum can be operated.

The oscillatory system motion values are determined by measuring the frequency and / or amplitude of the oscillatory system movements by monitoring the drive torque, the water level and / or the oscillatory system movements one-dimensionally, two-dimensionally or three-dimensionally.

As already mentioned, the oscillating system movement is measured by sensors, whereby sensors already present in a washing machine can also be used. The sensors can measure one-dimensional, two-dimensional or even three-dimensional movements. Preferably, those oscillatory system movements of the oscillatory system are determined which have a greater frequency than the respective nominal rotational speed n.

A particular advantage of the invention is that the already existing sensors can be used for the method according to the invention. Suitable sensors are displacement sensors, acceleration sensors or water level sensors, which are already used, for example, for the measurement of the load and the like. Examples of special sensors are load sensors, three-dimensional displacement sensors or analog pressure sensors.

In addition to the determination of the oscillating system movement, the actual speed fluctuation can also be used for the calculation of the optimum setpoint rotational speed. It is known that in conventional washing machine drive motors, when operated at a fixed target speed of around 55 min ^-1 , the entrained laundry has an influence on the respective actual speed, depending on whether just laundry is being carried by the driver or individual pieces of laundry from above fall. In the former case, the drum slows slightly during this rotation portion, as the pressed by the driver to the laundry drum wall Waschgutstücke shift the center of gravity of the drum. As the items to be washed fall, the drum can accelerate again during the short rotation stage. Most conventional washing machines are already equipped with controllers that counteract this phenomenon. Nevertheless, it is still measurable and can thus also serve as an indicator for the washing mechanics and be included in the calculation of the optimum target speed. It is also possible to measure oscillatory system movements via the motor control. Here, for example, the motor current can be measured.

Since the oscillating system movement is detected over a certain period of time Δts, several measuring points can be combined into one value, or a continuous measurement can be carried out.

Another aspect of the present invention is a washing machine with a laundry drum stored in a vibrating system and a programmable controller associated with a control program that defines the method of the present invention. By means of such a control unit, for example, the predetermined setpoint speeds can be specified, or else a program can be defined which previously determines the application speed and then selects suitable setpoint speeds.

Die Figur

eine schematische Vorderquerschnittsansicht einer Waschmaschine mit dem darin befindlichen Schwingsystem zeigt.

The invention will now be explained in more detail with reference to the following drawing, wherein

The figure

shows a schematic front cross-sectional view of a washing machine with the oscillating system therein.

Figure 1 shows in cross section a washing machine 1 in front view. The washing drum 2 with carriers 3 and the tub located around it 4. The tub 4 is suspended from four spring elements 6, which are additionally provided with dampers 8 at the bottom. Laundry drum 2, tub 4 and spring elements 6 form the oscillating system 10. The drum 2 is driven by the drive 16. For the measurement of oscillatory system movements are sensors 12 intended. Also shown is a control 14 that can perform the method of the present invention. In the laundry drum 2 shown are laundry items a, b, c.

At a first speed n1, the items to be washed a, b and c in the laundry drum 2 perform a rolling movement (not shown), wherein the drum 2 rotates very slowly, so that the items to be washed a, b, c not from the drivers 3 in the height be lifted but only in the lower part of the drum 2 are layered around each other.

At a slightly faster n2 speed, the drivers take along 3 individual pieces of laundry and drag them along over a certain turning section. This is shown for the laundry item b. At some point, the laundry item falls down again due to gravity. This is shown for the laundry item c. The speed n2 in this case is the speed for the optimal mechanics entry.

At an even higher speed n3 the items to be washed would already be pushed a little more strongly against the drum wall due to the centrifugal force and individual items of laundry would already rest against the wall. Depending on the load, it may still occur at this speed that individual items to be washed fall down, but there are also pieces of laundry which do not fall down for a full turn. This speed is thus already too high for an optimal mechanics entry.

LIST OF REFERENCE NUMBERS

1

Washing machine

2

washing drum

3

takeaway

4

tub

5

takeaway

6

spring elements

8th

damper

10

oscillating system

12

sensor

14

control

16

drive

a, b, c

laundry items

Claims (11)

1. Method of determining a target rotational speed (n) below a spreading-out rotational speed of a laundry drum (2) of a laundry treatment device (1) with a drive (16) and an oscillatory system (10), wherein a dependence of a respective mechanical action, which acts on stock (3) to be washed and disposed in the laundry drum (2), on the respective target rotational speed (n) of the laundry drum (2) is employed for the purpose of determining that target rotational speed (n) at which the mechanical action is greatest, characterised by the following steps:

   i) driving the laundry drum (2) at at least two different target rotational speeds (n1 to nx) below the spreading rotational speed for, in each instance, a predetermined time period (ftn),

   ii) measuring an oscillatory system movement value (s1 to sx) at each target rotational speed (n1 to nx) and

   iii) comparing the values (s1 to sx) with one another, determining the highest value (s) and determining that target rotational speed (n) which is associated with the highest oscillatory system movement value (s).
2. Method according to the preceding claim, wherein the respective mechanical action at the respective target rotational speed (n) is determined by measuring oscillatory system movements of the oscillatory system (10) which have a greater frequency than the respective target rotational speed (n).
3. Method according to one of the preceding claims, wherein the frequency and/or amplitude of the oscillatory system movements is or are measured in that the drive torque, water state and/or movements of the oscillatory system (10) are monitored one-dimensionally, two-dimensionally or three-dimensionally.
4. Method according to any one of the preceding claims, wherein the measuring of the oscillatory system movements is carried out by way of a travel sensor (12), an acceleration sensor (12), a pressure sensor (12) and/or a water state sensor (12).
5. Method according to any one of the preceding claims, further comprising the step of:

   iv) carrying out a laundry treatment process at the target rotational speed (n) determined in step iii).
6. Method according to claim 5, wherein step iv) is a washing and/or rinsing process.
7. Method according to any one of the preceding claims, wherein the steps i) and ii) are performed at at least three target rotational speeds (n1), (n2) and (n3).
8. Method according to any one of the preceding claims, wherein the steps i) and ii) are performed at at least four target rotational speeds (n1), (n2), (n3) and (n4).
9. Method according to any one of the preceding claims, wherein rotational speeds in the range between 35 min^-1 and 75 min^-1 are selected as target rotational speeds (n1 to nx).
10. Method according to claim 9, wherein the values 35 min^-1, 55 min^-1 and 75 min^-1 are selected as target rotational speeds (n1), (n2) and (n3).
11. Washing machine (1) with a laundry drum (2) mounted in an oscillatory system (10), a drive (16) and a programmable control unit (6) which is associated with a control program which uses a dependence of the respective mechanical action, which acts on a stock (3) to be washed and disposed in the laundry drum (2), on the respective target rotational speed (n) of the laundry drum (2) for the purpose of determining the target rotational speed (n) at which the mechanical action is greatest, wherein the control program performs a method characterised by the following steps:

    i) driving the laundry drum (2) at at least two different target rotational speeds (n1 to nx) below the spreading rotational speed for, in each instance, a predetermined time period (ftn),

    ii) measuring an oscillatory system movement value (s1 to sx) at each target rotational speed (n1 to nx) and

    iii) comparing the values (s1 to sx) with one another, determining the highest value (s) and determining that target rotational speed (n) which is associated with the highest oscillatory system movement value (s).

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