EP1293595A1 - Method for detecting an unbalance in a washing machine with a tub - Google Patents

Abstract

The invention relates to a method for detecting an imbalance in a washing machine with a tub (1), a rotatably mounted drum (2) and a riser (10) which has an opening to the lower region of the tub (1) and in which in one a pressure sensor (11) is arranged in the upper section of the riser. According to the invention, a liquid column is set in the riser (10), the drum (2) is rotated, the pressure in the riser is detected by the pressure sensor (11) and an imbalance is determined on the basis of the pressure detected in the riser. Building on this, a spin process of the washing machine is set as a function of the unbalance determined in a further method. In the washing machine according to the invention, a control device (20) controls the water inlet and / or the water outlet in such a way that a defined liquid column can be set. <IMAGE>

Description

The invention relates to a method for detecting a Unbalance in a washing machine with a riser with a pressure sensor and with a tub is a method for controlling a Spin process and a washing machine with a Riser and a pressure sensor.

In a known washing machine (DE 195 22 393 A1) is in a tub rotatably mounted a drum, wherein the drum with a variable speed motor is driven. The outlet area of the tub is connected to a riser that is inside the Washing machine from the connection point in the outlet area is led above. At the top of the riser are a Pressure sensor and several acceleration sensors arranged. During the inflow of fresh water, the Pressure sensor the water level inside the tub detected. The acceleration sensors measure that Acceleration of the tub and riser system. With the clogging sensors Accelerations of the washing drum detected by Imbalance inside the washing drum. It it is proposed to accelerate the Washing drum the unbalanced accelerations to two Measure times. At the first time the Acceleration aborted if the unbalance is too large, or it accelerates further until the second point in time. The final spin speed will depend on it determines the unbalance strength at the second time of measurement was measured with the acceleration sensors. Out Cost reasons are proposed for Accelerometer also use the level sensor. However, it is found that its output signal is too. is low in order to achieve the generate dynamic unbalance signal. The procedure and the device require to determine the unbalance dynamic signal, which leads back to the unbalance lead while the quasi-static signal, which is only due to a liquid level in the riser can be caused, not for consideration comes.

It is therefore an object of the invention to provide a method for Unbalance measurement and a washing machine with a pressure sensor and to provide a riser in which under Exploiting the sensitivity of a pressure sensor Level measurement of an unbalance can be detected precisely and reliably is.

This object is achieved with the features of claim 1, 11 or 17 solved.

In the method according to claim 1 is in a Riser leading to the lower part of the tub is open and at the top Pressure sensor is arranged for measuring unbalance Liquid column set. Pressure fluctuations within of the tub are in through the liquid column the riser preferably on an air column in the Transfer riser above the liquid column and detected there by the pressure sensor. The pressure at least a speed of the drum is detected and for determination the unbalance is recovered.

It is known that in a washing machine during the Slingshots of various types of imbalance occur can. A shape is a so-called static imbalance, which is also referred to as load case L0, in which the Ideally, the drum should only be in the radial direction to the symmetry or axis of rotation is deflected. Another case is that so - called dynamic unbalance, referred to as L0 ', at the washing drum is deflected in the axial direction. Besides there are the known load cases L1 to L4 that different mixed forms of static and dynamic Represent unbalance. Also the so-called quasi-static Imbalance is a sub-case of dynamic unbalance quasi-static unbalance is not one of the Main axes of inertia on the axis of symmetry of the drum.

The method of detecting an unbalance according to claim 1 and the corresponding subclaims are quite suitable particularly advantageous for the detection of a dynamic Unbalance and cases with mixed unbalance components, at which also have a dynamic imbalance.

In an advantageous embodiment, the Pressure measurement the liquid column to a predetermined Height set. So on the one hand it is possible from one predetermined reference pressure at the beginning of the rotation of the Start drum. On the other hand, the through the unbalance generated reproducible pressure changes because at a different height of the liquid column at the beginning of the Measurement each time a different pressure value is reached. A Such a calibration measurement can also be carried out at a specified level Reference speed take place. A pressure change will then occur compared to this reference measurement. It is however also possible at different heights of the Start liquid column at the beginning of the measurement and to the corresponding pressure value at the beginning of each Normalize measurement.

It is preferred to increase the measuring accuracy and thus the unbalance determination of the pressure at several different Drum speeds determined. Especially if the Pressure measured over a given speed range there is a time or speed-dependent pressure curve before dealing with previously determined pressure profiles lets compare to achieve an assignment. On such a comparison of pressure profiles or simply that Pressure dependency at a certain speed Different imbalances will be beneficial for each model a washing machine to set reference values for to get each model, which is then in a control unit serve as comparison data for the measurement.

Measurement noise, statistical fluctuations, e.g. Wave movements on the liquid inside the Suds container, or the like, can be by a Simply suppress averaging over time or eliminate. This will still record the unbalance more accurate. The average over time is advantageous one or more rotations of the drum are formed. Thereby any existing dynamic signal components from the Pressure sensor eliminated, which e.g. due to unbalance during the Rotation of the drum. It follows an approximately quasi-static recording of the pressure a speed. The time constant of the averaging is optimized that e.g. at a temporal Varying the speed (speed ramp-up) the pressure change can still be resolved in time during the speed change can.

To generate the liquid column in the riser a liquid level in the tub is advantageous set, this above the opening of the Riser pipe. This is particularly advantageous Liquid level in the tub below Bottom edge of the drum. Preferably as far as below the Drum that the rotating drum does not enter the Immerse liquid in the tub. This will make one Distribution of the liquid within the tub avoided by the drum and thus a change in Liquid column in the riser due to the Immersing the drum in the liquid.

The liquid column in the riser is through the Opening a water inlet and thus by letting it in from e.g. Fresh water and / or by pumping the Liquid that is already inside the tub, set. This can advantageously be a defined one Adjust liquid column.

To propose a change in the height of the liquid column, Avoid washing during or after the measurement advantageously pre-dewatered in the drum, e.g. is hurled. During the pre-spin advantageously pumped out the ejected liquid, so that the laundry has no or only when the imbalance is detected releases liquid to a small extent. A skid at low speed is enough.

In the process of controlling a spinning process According to claim 11, one of the first described the presence of an imbalance detected. If there is no imbalance, the the desired target spin speed. On the other hand, there is an imbalance that has a limit value exceeds, the spinning with one against the Desired spin speed reduced speed executed. Be advantageous for any unbalance strength or for Ranges of unbalance strengths different, maximum permissible Speeds set. Is the target spin speed anyway below the maximum allowed spin speed at the determined unbalance, the target spin speed not reduced.

If one is found, it is particularly advantageous First try to unbalance by redistributing the laundry Resolve unbalance yourself. This is advantageous through Reverse the laundry at low speed redistributed within the drum and then another Imbalance detection performed. This process can be carried out once or more before being scheduled is that the unbalance even when the laundry is redistributed cannot be resolved and therefore with reduced Spin speed is to be spun.

In the washing machine according to claim 17 is by a Control unit of the water inlet and / or the water outlet controllable in such a way that a sets the defined liquid column. This means that of such a washing machine is a method for determining the unbalance or to control the spin speed like feasible as described above.

In a very particularly advantageous embodiment the cross-section of the riser is smaller than the surface the liquid in the tub after the defined one Liquid column was set. By the ratio the cross sections or surfaces result in a Translation of the pressure inside the tub a higher pressure within the riser or Air column over the liquid column, so that a Pressure change is easily detected with the pressure sensor.

Embodiments of the invention are based on figures explained in more detail.

Fig. 1

eine schematische Darstellung des Zusammenwirkens einzelner Komponenten einer Waschmaschine,

Fig. 2

ein Ablaufschema zur Unwuchterfassung und Festlegung der Schleuderdrehzahl,

Fig. 3

die Drehzahl- bzw. Zeitabhängigkeit einer Druckänderung bei verschiedenen Unwuchten und

Fig. 4

eine Klassierungsmatrix zur Festlegung einer maximal zulässigen Schleuderdrehzahl.

Show it:

Fig. 1

1 shows a schematic representation of the interaction of individual components of a washing machine,

Fig. 2

a flow chart for unbalance detection and determination of the spin speed,

Fig. 3

the speed or time dependence of a pressure change with different imbalances and

Fig. 4

a classification matrix to determine a maximum permitted spin speed.

1 schematically illustrates the interaction various components of a washing machine. Within a tub 1 of the washing machine is rotatable mounted drum 2 arranged. In the tub 1 3 fresh water may be added via an inlet Detergent or the like supplied. The Fresh water inlet 3 is via a solenoid valve 4 with a House line connection connected. In the deepest area of the Suds container 1 an outlet 5 is arranged, the with a pump line 6 is connected. The drain line 6 is connected to a pump 7, which the liquid from pumps out the tub 1. One branches from outlet 5 Riser 10 from outside the tub 1 is led upwards. At the top of riser 10 a pressure sensor 11 is arranged, the pressure within the riser 10 measures. The drum 2 is replaced by a Motor 12 driven.

A program sequence control unit 20 is used to control the Sequence of the individual programs of the washing machine. The Control unit 20 controls a drive unit 21 of the engine 12 on. By controlling the drive unit 21 the drum 2 forward or backward at one speed during normal washing operation of approx. 30 turns per minute and continuously adjustable when spinning driven from 0 to approx. 1400 revolutions per minute. The circulation pump 7 is furthermore controlled by the control unit 20 and the solenoid valve 4 controlled. Via a signal and Communication line 22 is the control unit with a Sensor electronics 23 in connection, which in turn the signal subjected to a signal conditioning by the pressure sensor 11 and evaluates if necessary.

The control unit 20 can be connected via the line 22 Send synchronization signal to the sensor electronics 23, so that, for example, the measurement of the time-dependent pressure synchronized with the increase in speed by the motor 12 becomes. In normal washing mode, the pressure sensor 11 the height of the water column in the riser 10 at Filling the tub 1 with water measured. Thereby the solenoid valve 4 can be closed as soon as one desired liquid level within the Suds container 1 was reached.

Fig. 2 shows an embodiment of the program flow The control unit determines the spin speed 20. After the start of the spin program (S0) in a pre-spin is carried out in a step S1. The Pre-spinning is at a low drum speed 2 in the range of 100 to 500 revolutions per minute executed. A speed of 300 is preferred Revolutions per minute because this is above the Speed range when running through the speed to determine the Final spin speed is (see Fig. 4). The most of the amount of liquid is already from the wash away. In addition, the counter REG is opened in step S1 Set zero and the spun liquid pumped out. At step S2, the pumping of the Liquid completed and by introducing Fresh water via inlet 3 a defined level of Liquid set in the riser. The level is set so that the opening of the riser 10 to the outlet 5 completely immersed in liquid is, i.e. there is no air connection between the Air column in the riser 10 and the air in Suds container 1. Furthermore, this defined one is sufficient Liquid column level of the condition that in this the Liquid level in the tub 1 so far below the Bottom edge of the drum 2 is that even when deflected the drum 2 due to imbalance not in the Liquid immersed.

After the liquid level is set (S2), in step S3 a pressure measurement with the drum 1 stopped carried out, the pressure value P1 being measured. After that starts in step S4, the acceleration of the speed Drum. The drum is preferably included accelerated steady increase in speed. At step S5 after a specified time after the start of the ramp-up a second pressure value P2 is measured in the drum. Preferably becomes the second pressure value P2 in a time range of 15 measured up to 30 seconds after start-up, preferably at 20 seconds.

In step S6 it is checked whether the difference between the pressure values (P1 - P2) is greater than a pressure limit value (P1 - P2> P _unbalance ). If the pressure P2 has not fallen below the pressure P1 by at least the pressure value P _unbalance , the normal final spin speed is set in step S7b. This means that the final spin speed is set here, which was originally specified by the program sequence control unit or which was selected by an operator. Instead of immediately executing step S7b after step S6, step S7a can optionally be used to check whether a total waiting time has been exceeded since the start of the startup. This waiting time is preferably 2 to 10 seconds longer than the time at which P2 is measured for the first time in step S5. If this waiting time has not expired, the process from step S5 is repeated again until the waiting time has been exceeded or the pressure drop is greater than P _unbalance . The waiting time in step S7a ensures that a pressure drop greater than P _imbalance does not occur even at a higher speed during startup.

If the pressure drop in step S6 is greater than P _unbalance (P1-P2> P _unbalance ), the method continues with step S10. In step S10, it is checked whether the counter REG = 3. If this is not the case, the counter is increased by one in step S11 and the laundry is redistributed in step S12. For this purpose, the drum is stopped and operated in a reversing mode at low speed, for example at 10 revolutions per minute, the laundry being redistributed within the drum. The method then continues in step S2 or optionally in step S4. If it is determined in step S10 that the counter REG = 3, the rotational speed is determined as a function of the level of the unbalance, the size of the unbalance depending on the level of the pressure difference P1 minus P2 (see below).

The steps S10, S11, S12 serve to cancel one Unbalance if it exceeds a certain value and possibly by redistributing the laundry within the Drum can be removed again. Here was exemplarily assumed that after a three Attempting to redistribute the unbalance cannot be canceled can, and therefore thrown at the reduced speed must become. Redistribution can optionally be dispensed with or as a setting value in step S10 instead of Number 3 another number can be used, for example a number between 2 and 10. The stated time values are exemplary and are depending on the Washing machine model for as short a time as possible optimized detection of unbalance optimized.

At step S15, the speed of the drum may continue increased until a minimum speed or acceleration time is reached in order to determine the to allow maximum spin speed (Fig. 3 and 4).

3 shows an example of the dependency on the sensor measured pressure by time. Curve A shows that the Speed is ramped up almost linearly with time. This changes the characteristics of the curves Not over the speed. Curve B shows the case if there is no imbalance in the drum. The curves C to G show the curves in load case L0 ', i.e. if only there is a dynamic imbalance, so that the drum in Ideally only deflected in the axial direction. The curves H and I show a mixed form of dynamic and static Unbalance, here the so-called load case L1. At curve C an imbalance of 420 g was set. At curve D one Unbalance of 520 g, with curve E an unbalance of 700 g, at Curve F an unbalance of 1000 g and curve G a Unbalance of 1600 g. In curve H 420 g were dynamic Unbalance and 420 g static unbalance set. When cornering I became 700 g dynamic unbalance and 420 g static Unbalance set. With increasing unbalance, the maximum, temporal gradient of the unbalance.

Without unbalance (curve B), the pressure increases over time easy to. At all times the difference is P1 - P2 < 0. On the other hand, the difference P1 - P2 increases during imbalance of the speed ramp-up, whereby the pressure drops by starts earlier, the greater the imbalance.

4 shows an example of a decision matrix or a Decision diagram to determine the maximum allowable Speed in the presence of an unbalance. In the The decision matrix is the change in pressure over time applied since speed ramp up. Multiple speed / time classes I to V are used to determine the maximum permissible speed. The assignment between the measured Pressure history and the class is carried out as follows: The measured pressure curve lies in the time range from 15 to 40 seconds (preferably in the range of 20 to 35 Seconds) to 80% within one of the speed / time class, so the corresponding curve of the respective Assigned to class. Thereby a tolerance of 80% Match provided to measure outliers consider. If the measured curve of the pressure 80% within a of the speed classes, it becomes this speed class assigned.

For example, curve B of FIG. 3 becomes the Speed class I assigned at which the maximum permissible Speed is unlimited, i.e. the maximum possible Speed of the washing machine can be used. The Curve C falls into speed range II, the maximum Spin speed is 1200 revolutions per minute. The Curve G of Fig. 3 falls in the centrifugal class V, i.e. on Skidding is not permitted here. Has already been one here Redistribution e.g. tried three times, so one Error message issued ', causing a user of the Washer is informed that a spin cycle is not is possible. The curve F falls in the area IV, so that the maximum spin speed is 700 revolutions per minute is. The curve E falls in the speed range III, see above that the maximum spin speed 1000 revolutions per Minute.

The specified maximum spin speeds of the various classes are only given here as examples. The number of classes and the course of the class boundaries are only shown as examples. In a further embodiment, provision can be made for the pressure to be determined only at one point in time, for example at 28 seconds, a spinning class being assigned to each pressure range. For example, a pressure P2 - P1> 0 (mm H ₂ O) corresponds to centrifugal class I. A pressure P2 - P1 = -14 to - 17 mm water column corresponds to centrifugal class IV.

LIST OF REFERENCE NUMBERS

1:

tub

2:

drum

3:

Intake

4:

magnetic valve

5:

outlet

6:

evacuation line

7:

pump

10:

riser

11:

pressure sensor

12:

engine

20:

control unit

21:

drive unit

22:

Signal and communication line

23:

sensor electronics

Claims (15)

Method for detecting an imbalance in a washing machine with a tub (1), a rotatably mounted drum (2) and a riser (10) which has an opening to the lower area of the tub (1) and in which a pressure sensor is located in an upper area (11) is arranged with the steps: Setting a liquid column in the riser (10), Turning the drum (2), Detecting the pressure in the riser (10) by the pressure sensor (11), and Determination of an imbalance based on the detected pressure, the liquid column being set to a predetermined height in particular before the start of the pressure measurement. A method according to claim 1, characterized in that the pressure is detected depending on the speed. Method according to Claim 1 or 2, characterized in that a change in pressure is detected over a predetermined speed range of the drum (2). Method according to one of the preceding claims, characterized in that a time average of the detected pressure is formed, the pressure in particular being averaged during one or more rotations of the drum (2). Method according to one of the preceding claims, characterized in that the liquid column in the riser (10) is adjusted by setting a liquid level in the tub (1) above the opening of the riser (10) to the tub (1), preferably the Liquid level is below the lower edge of the drum (2). Method according to one of the preceding claims, characterized in that in order to adjust the liquid column, a water inlet is opened until a predetermined height of the liquid column has been reached or is likely to be set by the water wake. Method according to one of the preceding claims, characterized in that in order to set the predetermined height of the liquid column, the liquid is pumped out of the tub (1) until the defined liquid column is reached. Method according to one of the preceding claims, characterized in that the laundry is dewatered, in particular pre-spun, before the imbalance is detected. Method for controlling a spinning process of a washing machine, wherein after detecting an imbalance according to one of the preceding claims a spin is carried out at a target spin speed if no unbalance has been determined or the unbalance is below a limit value, or A spin is carried out at a reduced speed below the target spin speed if the limit value of the unbalance is exceeded for the target spin speed. Method according to Claim 9, characterized in that when the limit value is exceeded and before spinning at a reduced spin speed, the laundry is redistributed in the drum (2), the unbalance is detected when the laundry is redistributed and the speed is determined again, preferably the above steps once or several times before finally spinning at a reduced spin speed. Method according to one of claims 9 or 10, characterized in that the reduced spin speed is determined as a function of the magnitude of the unbalance, the spin speed reduction increasing with greater unbalance and preferably the amount of the spin speed reduction being based on a classification of the unbalance. Method according to claim 11, characterized in that the classification takes place on the basis of the speed-dependent unbalance. Washing machine with a tub (1), a rotatably mounted drum (2) and a riser (10) which has an opening to the lower area of the tub (1) and in which a pressure sensor (11) is arranged in an upper area, in particular for carrying out a method according to one of the preceding claims, characterized in that a liquid column in the riser (10) can be set by a control device (20) for detecting an imbalance of the drum (2). Washing machine according to claim 13, characterized in that the cross-sectional area of the riser (10) is smaller than the surface of the liquid in the tub (1) which results when the liquid column is adjusted. Washing machine according to claim 13 or 14, characterized in that the riser (10) opens into the lye container (1) in a region which is arranged opposite the drum mounting.

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