Method for operating a washing machine and washing machine

Abstract

The invention relates to a method for operating a washing machine with a tub (1) for holding water, a drum (2) rotatably mounted in the tub (1) for holding laundry (4), a heating element (3) for heating the water, a circulation system for conveying the water from a first area of ​​the tub (1) to a second area of ​​the tub (1), and a control and / or regulating device for controlling and / or regulating a washing program, comprising a heating process during the execution of a washing program, wherein the water level in the tub (1) is controlled and / or regulated during the heating process such that the water in the tub is simultaneously heated by means of the heating element (3) and conveyed by means of the circulation system from the first area of ​​the tub (1) to the second area of ​​the tub (1).Furthermore, the invention relates to a corresponding washing machine.

Description

[0001] The invention relates to a method for operating a washing machine and a washing machine. In particular, the invention relates to a method for operating a washing machine comprising a tub for holding water, a drum rotatably mounted in the tub for holding laundry, a heating element for heating the water, a circulation system for conveying the water from a first area of ​​the tub to a second area of ​​the tub, and a control and / or regulating device for controlling and / or regulating a washing program, comprising a heating process during the execution of a washing program, and a correspondingly designed washing machine.

[0002] The primary goal of the heating process in a washing machine is the most efficient possible transfer of heat energy between the heating element and the laundry, while simultaneously minimizing water consumption and operating cycles. This energy transfer occurs via heated free liquor. It is optimal when there is a continuous exchange between the concentrated and heated free liquor. Depending on the washing machine model, particularly whether it has or does not have a water bath, and the required heating temperatures, two different methods are currently in use. In the classic method, heat energy transfer between the heated and concentrated liquor is achieved through high water levels. The liquor exchange occurs via the absorbency of the laundry. This method is generally used in washing machines without a water bath.

[0003] In washing machines with unregulated recirculation, the water exchange occurs when the recirculation system is activated. The heated, free-flowing water is introduced into the laundry via the recirculation system. The water level drops very quickly because the recirculation system's pump operates at a high flow rate, which cannot be varied. This, in turn, greatly increases the risk of overheating due to the rapidly changing water levels. While it's possible to correct the water level by continuously adding water, this results in high overall water consumption. Therefore, the heating element and recirculation system are always switched on and off sequentially. However, this leads to frequent switching cycles and a longer heating process, as the water levels must readjust each time.The introduction of the flooding method makes the heating process more efficient compared to traditional heating with high water levels, but it is a long process.

[0004] The invention thus addresses the problem of providing a method for operating a washing machine and a washing machine whose heating process for heating free liquor can be carried out more time-efficiently using a recirculation system.

[0005] According to the invention, this problem is solved by a method with the features of claim 1 and a washing machine with the features of claim 10. Advantageous embodiments and further developments of the invention are described in the following dependent claims.

[0006] The advantages achievable with the invention lie in the fact that the heating process is significantly shortened by simultaneously heating and circulating the water and detergent. Ideally, each heating process can thus consist of only one heating cycle. This minimizes the stress on the components due to the reduced number of switching cycles. This applies to both the heating element and the circulating solution. In addition to the advantages already described, the time saved in heating results in further benefits during the program sequence. This time can be used to extend the washing process. Particularly at high temperatures, this leads to better washing results. Alternatively, a shorter program cycle can be achieved. Furthermore, the reduced stress on the components allows for design and component-related savings, which lower manufacturing costs.

[0007] The invention relates to a method for operating a washing machine with a tub for holding water, a drum rotatably mounted in the tub for holding laundry, a heating element for heating the water, a circulation system for conveying the water from a first area of ​​the tub to a second area of ​​the tub, and a control and / or regulating device for controlling and / or regulating a washing program, comprising a heating process during the execution of a washing program, wherein the water level in the tub is controlled and / or regulated during the heating process such that the water in the tub is simultaneously heated by means of the heating element and conveyed by means of the circulation system from the first area of ​​the tub to the second area of ​​the tub.By controlling and / or regulating the water level to a suitable level, simultaneous heating with excellent fleet exchange is enabled. The water level is preferably above the heating element, relative to the washing machine's standard operating position.

[0008] Preferably, the water level in the lye tank during the heating process is controlled and / or regulated by adjusting the flow rate of the circulating system and / or the rotation rate of the drum. Preferably, the water level is controlled and / or regulated by adjusting the flow rate of the circulating system and the rotation rate of the drum such that an equilibrium between lye discharge and input is achieved. A quasi-stationary water level is preferably maintained.

[0009] In a preferred embodiment, the heating process comprises the following steps: a) Setting 100% saturation in the laundry in the drum by adding water to the tub, b) Adding further water as free liquor so that the water level in the tub is above the heating element and below the drum, c) Rotating the drum according to a selected speed profile, d) Pulsating the free liquor into the laundry while activating the overflow system, e) Deactivating the activated overflow system when a minimum water level is reached in the tub, resulting in a specific discharge volume flow corresponding to the speed profile and a rise in the water level, f) Starting a timer following step e) as soon as a predetermined starting water level is reached, g) Stopping the timer as soon as a predetermined stopping water level or a predetermined time limit is reached.h) Calculating the specific discharge volume flow rate using a result from a time measurement, and i) increasing the calculated specific discharge volume flow rate to its final value in order to maintain a continuous water level with the heating element and recirculation system activated simultaneously.

[0010] In step a), the laundry is preferably pre-treated to 100% saturation using a water inlet control system before the heating process. This ensures that the laundry cannot absorb any additional water during the subsequent heating phase. While the laundry may temporarily absorb additional water in the form of peeling water, this drips off the laundry again after a delay. Preferably, a rotational speed profile is selected in the subsequent steps that supports the peeling process.

[0011] Subsequently, in step b), a required quantity of water up to the heating element level, plus a predetermined quantity of circulating water, is preferably introduced into the tub. The water level preferably remains below the drum level. The circulating water quantity is preferably available to the recirculation system for the subsequent liquor exchange at its maximum capacity. To prevent the laundry from being sucked into the tub, there is preferably no contact between the free liquor and the laundry.

[0012] To precisely control continuous liquor exchange, an initial measurement of the specific discharge flow rate is performed, which depends on the selected rotational speed profile, the amount and type of laundry in the drum. With continuous introduction of free liquor, the discharge flow rate will stabilize at a quasi-steady state. It is preferably designed as a feedforward control for a subsequent water level control system.

[0013] The measurement of the specific discharge volume flow rate comprises steps c) to h). First, a selected rotational speed profile is initiated, and then the entire free liquor is introduced into the wash via the recirculation system in pulses. The maximum rotational speed of the recirculation system is preferably selected. Subsequently, the recirculation system is deactivated when a minimum level is reached. A discharge volume flow rate specific to the rotational speed profile is established. The water level rises. A time measurement is then started from the point at which a defined initial level is reached and stopped as soon as a defined stop level or time limit is reached. The specific discharge volume flow rate is then preferably calculated using specifications for the wash tank geometry and the result of the time measurement.

[0014] Step c) is preferably continued continuously from its beginning during steps d) to i). Due to the sustained rotational speed profile, the previous water level, including the circulating water volume, will be restored after steps e) to h). Step i) preferably comprises a water level control with feedforward control and manipulated variable limiting based on a PI controller. The aim is to maintain a continuous water level while simultaneously activating the heating element and the recirculation system. The target water level lies between the heating element and drum levels. Preferably, the previously determined specific discharge flow rate is used as feedforward control. During a start-up phase of the controller, the discharge flow rate is preferably increased to its maximum value. This feedforward control may be sufficient to establish a continuous exchange of the liquor. If not, other parameters are used for adjustment.

[0015] Due to dynamic variations in the water level during the process, the feedforward control may be insufficient and must then be compensated. In this case, the target water level, in the form of a target pressure, and the measured actual water level, in the form of an actual pressure, preferably serve as input variables. Based on a pressure / volume characteristic curve that takes the brine geometry specifications into account, a target volume and an actual volume of the free liquor are preferably calculated. The difference between these two values ​​yields a control deviation, which describes the amount of free liquor that must be pumped through the recirculation system to compensate. The time required to compensate for the control deviation is determined by gain factors of the controller. The sum of the controller manipulated variable and the feedforward control is preferably limited according to the flow rates of the recirculation system. Overflow of the integrator component is preferably prevented by an anti-windup mechanism.Subsequently, a target speed for the controlled circulation is calculated, preferably based on a circulation characteristic curve. Because a continuous exchange of freshly heated free liquor and bound liquor now takes place, the energy flow into the laundry is increased, and a reheating process is further avoided.

[0016] Therefore, the following steps are preferably carried out during and / or following step i): Measuring an actual pressure, calculating a target volume and an actual volume of the free liquor based on a target pressure and the measured actual pressure and a pressure-volume characteristic curve, calculating a difference between the calculated actual volume and the calculated target volume, and using the calculated difference as a controller control variable to regulate a target rotational speed of the drum, at which a continuous water level is achieved with the heating element and recirculation system simultaneously activated.

[0017] In a preferred embodiment, the method further includes determining a time in which the calculated difference is used as a controller control variable, based on gain factors of a controller that regulates the target rotational speed.

[0018] Preferably, the method further comprises summing the calculated discharge volume flow rate and the controller control variable and implementing a control variable limit on the sum corresponding to a delivery capacity of the bypass system.

[0019] In a preferred embodiment, the method further includes performing an anti-windup.

[0020] Preferably, step c) is repeated with another speed profile different from the speed profile, and steps d) to g) are repeated when the time measurement is stopped by the predetermined time limit in step g). Alternatively, preferably, another heating process is initiated when the time measurement is stopped by the predetermined time limit in step g).

[0021] In a preferred embodiment, the target rotational speed is calculated based on a flow characteristic curve and the calculated discharge volume flow rate.

[0022] The invention further relates to a washing machine with a tub for receiving water, a drum rotatably mounted in the tub for receiving laundry, a heating element for heating the water, a circulation system for conveying the water from a first area of ​​the tub to a second area of ​​the tub, and a control and / or regulating device for controlling and / or regulating a washing program and a method according to one or more of the embodiments described above.

[0023] The term "washing machine" refers to a washing machine or a combination appliance such as a washer-dryer.

[0024] An embodiment of the invention is shown schematically in the drawings and is described in more detail below. It is shown schematically and not to scale. Fig. 1 a partial cross-sectional view of a washing machine according to the invention; and Fig. 2 a block diagram of a water level control according to a method according to the invention.

[0025] Fig. 1Figure 1 shows a partial cross-sectional view of a washing machine according to the invention. The washing machine has a tub 1 for holding water, a drum 2 rotatably mounted in the tub 1 for holding laundry 4, a heating element 3 for heating the water, a circulation system (not shown) for conveying the water from a first area of ​​the tub 1 to a second area of ​​the tub 1, and a control and / or regulating device (not shown) for controlling and / or regulating a washing program.The control and / or regulating device is further configured to carry out a heating process of a washing program, such that the water level in the tub 1 is controlled and / or regulated during the heating process in such a way that the water in the tub is simultaneously heated by the heating element 3 and pumped from the first section of the tub 1 to the second section of the tub 1 by means of the circulation system. The circulation flow rate V is located between a drum level (in the form of a drum pressure pTr) and a heating element level (in the form of a heating element pressure phk). A target water level (in the form of a target pressure ptarget) is located between the drum level and the heating element level.

[0026] Fig. 2Figure 1 shows a block diagram of a water level control system according to a method according to the invention. The aim of the water level control system is to maintain a continuous water level while simultaneously activating the heating element and the recirculation system, wherein the in Fig. 1 The target water level shown is achieved. A previously determined specific discharge volume flow rate. V sprouting is used as a feedforward control. During the start-up phase of a controller 5 of the washing machine, the specific discharge volume flow rate is slowly increased to its final value, whereby dynamic deviations in the water level during the heating process are compensated for by the controller 5. The target water level in the form of the target pressure serves as the input variables. p Should and the measured actual water level in the form of the actual pressure p IsBased on a target pressure / volume characteristic curve 6 and an actual pressure / volume characteristic curve 9, a target volume Vtarget and an actual volume Vactual of the free fleet are calculated. A difference between these two values ​​results in a control deviation. ΔV, which describes the amount of free-flowing water that must be pumped through the flood control system to equalize the water level. A time when the deviation from the standard occurs. ΔV The compensation required is determined by the gain factors of the controller 5. A sum of the controller input variable and the feedforward control is limited according to the flow rates of the recirculation system by means of an input variable limit 7. Subsequently, based on a recirculation characteristic curve 8, a target rotational speed ntarget of the drum is calculated for controlled recirculation, at which a continuous water level is achieved with the heating element and recirculation system simultaneously activated. Reference symbol list

[0027] 1. Tub 2. Drum 3. Heating element 4. Laundry 5. Controller 6. Setpoint pressure / volume characteristic curve 7. Control variable limitation 8. Flooding characteristic curve 9. Actual pressure / volume characteristic curve

Claims

1. Method for operating a washing machine with a tub (1) for holding water, a drum (2) rotatably mounted in the tub (1) for holding laundry (4), a heating element (3) for heating the water, a circulation system for conveying the water from a first area of ​​the tub (1) to a second area of ​​the tub (1) and a control and / or regulating device for controlling and / or regulating a washing program, comprising a heating process during the execution of a washing program, wherein the water level in the tub (1) is controlled and / or regulated during the heating process such that the water in the tub is simultaneously heated by means of the heating element (3) and conveyed by means of the circulation system from the first area of ​​the tub (1) to the second area of ​​the tub (1).

2. Method according to claim 1, characterized by the fact thatthe water level in the lye container (1) is controlled and / or regulated in the heating process by adjusting a volume flow conveyed by the circulation system and / or a rotation rhythm of the drum (2).

3. Method according to claim 1 or 2, characterized by the fact thatThe heating process comprises the following steps: a) Setting 100% saturation in the laundry (4) in the drum (2) by adding water to the tub (1), b) Adding further water as free liquor so that the water level in the tub (1) is above the heating element (3) and below the drum (2), c) Rotating the drum (2) according to a selected speed profile, d) Pulsating the free liquor into the laundry (4) while activating the overflow system, e) Deactivating the activated overflow system when a minimum water level is reached in the tub (1), resulting in a specific discharge volume flow corresponding to the speed profile and a rise in the water level, f) Starting a timer following step e) as soon as a predetermined starting water level is reached, g) Stopping the timer.as soon as a predetermined stop water level or a predetermined time limit is reached, h) calculate the specific discharge volume flow rate using a result of the time measurement, and i) increase the calculated specific discharge volume flow rate to its final value in order to maintain a continuous water level with the heating element (3) and recirculation system activated simultaneously.

4. Method according to claim 3, characterized by the fact thatThe following steps are carried out during and / or following step i): - Measuring an actual pressure, - Calculating a target volume and an actual volume of the free liquor based on a target pressure and the measured actual pressure and a pressure-volume characteristic curve, - Calculating a difference between the calculated actual volume and the calculated target volume, and - Using the calculated difference as a control variable to regulate a target rotational speed of the drum (2) at which a continuous water level is achieved with the heating element (3) and recirculation system activated simultaneously.

5. Method according to claim 4, characterized by Determining a time in which the calculated difference is used as a controller control variable, based on gain factors of a controller (5) that regulates the set speed.

6. Method according to one of the preceding claims 4 or 5, characterized bySumming the calculated discharge volume flow rate and the controller control variable, and implementing a control variable limit on the sum according to a delivery rate of the recirculation system.

7. Method according to claim 6, characterized by Performing an anti-windup.

8. Method according to any one of the preceding claims 3 to 7, characterized by the fact that Step c) is repeated with another speed profile different from the speed profile, and steps d) to g) are repeated, or another heating process is set up if the time measurement is stopped by the predetermined time limit in step g).

9. Method according to any one of the preceding claims 4 to 8, characterized by the fact that The target rotational speed is calculated based on a flow characteristic curve and the calculated exhaust volume flow rate.

10. Washing machine with a tub (1) for receiving water, a drum (2) rotatably mounted in the tub (1) for receiving laundry (4), a heating element (3) for heating the water, a circulation system for conveying the water from a first area of ​​the tub (1) into a second area of ​​the tub (1) and a control and / or regulating device for controlling and / or regulating a washing program and a method according to one of the preceding claims.

Images