Patent Application
20110126869
The invention relates to a water-conducting household appliance, in particular a dishwasher or washing machine, according to the preamble of claim 1.
A reduction in energy consumption is very important for water-conducting household appliances. Such an energy reduction can be achieved, for instance, by means of reduced process temperatures.
For example, a generic dishwasher has a control device in which at least one wash program, especially one at reduced process temperatures, for example a low-temperature program operating below 50° C., is stored. The low-temperature program is activated by the user by means of manual operation of a selector element. By means of the low-temperature program, the control device carries out a wash cycle or a rinsing cycle to clean the items to be washed.
In particular, the continuous use of low-temperature programs, such as a so-called gentle wash or a glass program, during which maximum temperatures of approx. 50° C. are achieved, results in greasy films of dirt collecting in the interior of the washing container. To remove such greasy films of dirt the user must use a special machine cleaner. For this the dishwasher must be operated without crockery at a temperature of least 65° C. Alternatively, from time to time the customer can independently use a high-temperature program, e.g. a 65° C. or intensive 70° C. program.
In both cases the cleaning of the device is therefore at the user's discretion. If the device is cleaned too frequently, energy consumption rises. In contrast, if the device is not cleaned often enough, the result is impaired cleaning of the items to be washed.
The object of the invention is to provide a water-conducting household appliance, in particular a dishwasher or washing machine, with which a perfect cleaning result can be lastingly achieved with the least possible expenditure of energy.
The object is achieved by the features of claim 1. Preferred developments of the invention are disclosed in the subclaims.
The invention is based on a water-conducting household appliance, in particular a dishwasher or washing machine, designed to carry out at least one wash program, especially a low-temperature program. The at least one wash program may have a plurality of program steps, such as e.g. prewashing, cleaning, intermediate washing, rinsing and drying, which are performed consecutively to clean and dry items to be washed. To perform the program steps a control device can be provided in which the individual wash programs are stored.
According to the invention, a special cleaning program for cleaning the washing container, particularly by applying washing liquid thereto, is carried out when there is a start signal. The start signal therefore activates the special cleaning program inside the appliance without the need for a decision by the user. The special cleaning program can therefore always operate if there are actual or expected deposits of dirt in the hydraulic system of the water-conducting household appliance. To clean the washing container, which also includes the sump arranged in the base area of the washing container of a dishwasher with a filter assembly for cleaning circulated washing liquid, heated washing liquid circulated by a circulation pump is applied to the interior of the washing container, the heated wash liquor collecting in the sump once it has flowed through the filter assembly.
To generate the start signal, a control device of the water-conducting household appliance is assigned a signal generating device, by means of which the start signal can be generated in various ways.
According to a particularly simple embodiment, the signal generating device can have a counter unit which, for example, when certain relevant events occur, increments by at least one count value and on reaching a limit counter status generates a start signal. Meaningful signal generation can occur when the counter unit increments as a function of the number of wash cycles performed and/or the temperature profile of preceding wash cycles and/or the level of soiling of the items to be washed. Generally speaking, all influencing variables which have an influence on the soiling of the hydraulic circuit of the water-conducting household appliance may be considered here. Alternatively by recording the volume of water which has flowed into the water-conducting household appliance, the selected program and consequently the temperature profile can be inferred.
For a more precise assessment of the level of soiling in the hydraulic circuit of the household appliance, preferably several of the aforementioned influencing variables can be recorded. Furthermore, different count values can be assigned to each of the recorded influencing variables. As a result the influencing variables can be weighted against each other according to their importance for the soiling of the device. For example, a wash cycle performed with a high-temperature program can be assigned a count value of 1. A wash cycle performed with a low-temperature program, in comparison, can be assigned a count value of 2, as reduced process temperatures accelerate the soiling of the household appliance.
The invention can be technically achieved particularly easily if the counter unit increases its counter status for each wash cycle performed by the
Alternatively, or in addition to the counter unit, the signal generating device can have a soiling sensor, for instance a deposit sensor, which can record greasy films of dirt in areas prone to soiling of the water-conducting household appliance. In the case of the dishwasher, such areas prone to dirt are the base area of the washing container or the sump area in which the soiling sensor can be arranged, for instance. If a limit level of soiling is exceeded, a start signal can be generated by means of the soiling sensor. Alternatively, formation of a deposit may also be detected through the filter density. The loading of the electric motor driving the recirculation pump is recorded and evaluated for this purpose.
Unlike the aforementioned counter unit, a closed control loop exists here with the soiling sensor and the control device.
Usually the water-conducting household appliance may have different wash programs which can be selected by the user. In the case of a dishwasher, for example, these are a low-temperature program in which the washing liquid can be heated to somewhere in the region of 50° C., a normal program with washing liquid temperatures in the order of up to 65° C., and a high-temperature program in which washing liquid temperatures can rise to approx. 70° C. Preferably the special cleaning program can be identical to the high-temperature program selectable by the user, as a result of which altogether the data requirement or storage time in the control device can be reduced.
According to the invention the control device can activate the special cleaning program automatically, in other words, without the involvement of the user. The control device can therefore perform an impending wash cycle with the special cleaning program regardless of a wash program selected by the user. When there is a start signal, the special cleaning program therefore takes priority over the wash program selected by the user and runs automatically in the background.
As aforementioned, in the special cleaning cycle washing liquid is applied to at least the areas prone to soiling of the water-conducting household appliance, the temperature of which is hot enough to remove the grease deposits or films of dirt. A washing liquid temperature on a scale which permits the breakdown of grease is preferred, in other words somewhere in the region of 65 to 70° C.
The special cleaning program may therefore differ from a normal cleaning program as a result of substantially higher process temperatures in at least one or more subprogram sections.
The special cleaning program may, however, also differ with regard to a flow guide for the washing liquid in the hydraulic circuit compared to a normal wash program. In the case of a dishwasher as is known at the start of a cleaning program step both a detergent is added to the washing liquid as well as the washing liquid is heated to a high cleaning temperature. The cleaning temperature is selected such that a mixing temperature in the order of 50° C. is normally produced in the dishwasher interior of the washing container. This mixing temperature is produced by the temperature of the items to be washed, the temperature of the washing liquid and the temperature of the washing container.
In comparison, in a preferred process control in the special cleaning program, in particular during the heating phase up to the cleaning temperature, an upper spray plane can be put out of operation. In this way the entire hydraulic circuit only operates via a lower spray plane close to the base of the washing container. The items to be washed in the upper spray plane are therefore not included in the hydraulic circuit during the heating phase. Accordingly, the upper items to be washed do not contribute to a reduction in the temperature of the washing liquid, as a result of which the mixing temperature produced near the base of the washing container is increased, namely in comparison with a mixing temperature produced in a normal wash program.
Alternatively and/or in addition, a higher hydraulic or mechanical removal rate on one or more spray planes can also be achieved by increasing the speed of the circulation pump. At higher circulation pump speeds the volume of washing liquid must be adjusted accordingly.
On the one hand, for instance, a so-called gentle wash or glass program, which operates at reduced process temperatures, is to be understood by the aforementioned low-temperature program. In addition, a wash program in the sense of the invention is also to be understood by a low-temperature program, as may be used in a dishwasher with an external drying system.
In such a dishwasher during the drying phase the moisture-laden air is fed from the dishwasher interior e.g. into an external sorption column with zeolite material, in which moisture is extracted from the air. The air dried in this way is then returned to the dishwasher interior.
With such an external drying process, heating the washing liquid to approx. 60 to 70° C. in the upstream rinsing step ceases to apply. Such heating of the washing liquid in the rinsing step is known to support the drying of items to be washed in accordance with the condensation principle. In contrast, in a dishwasher with an external drying system the washing liquid is not heated during the rinsing step but a mixing temperature in the order of approx. 30° C. is produced on account of the heat of the items to be washed themselves.
Below two exemplary embodiments of the invention are described with the aid of the appended figures.
The figures show:
The circulation line 9 is fluidically connected to the spray arms 7, 8 via supply lines 14, 15. Downstream of the circulation pump 13 is a heating element 12 designated as a water heater, for instance a continuous-flow heater.
Furthermore, a fresh-water supply line 16 and a drain line 17 are connected to the sump 11, in which a drain pump 18 for pumping washing liquid out of the washing container 1 is arranged.
Downstream of the heating element 12 a branching point 21 is provided in the circulation line 9, at which the two supply lines 14, 15 branch off. At the branching point 21 there is an alternative water distributor designed as a three-way control valve 25. The alternative water distributor 25 connects the circulation line 9 in its switch position shown in
The program runs illustrated in the temperature-time diagram show the individual subprogram steps of a wash cycle, namely prewashing V, cleaning R, intermediate washing Z, rinsing K and drying T. These subprogram steps are performed by means of a control device 27 which is connected via signal lines 26, shown by a dotted line, to the respective device components.
In addition, three actuating elements 28, 29, 30 are assigned to the control device 27. By means of the actuating elements 28, 29, 30 the user can select whether the control device 27 should perform a wash cycle with a low-temperature program I, a normal program II or a high-temperature program III.
In
In accordance with
In an embodiment which is technically particularly easy to achieve, the counter unit 39 is only in signal connection with the input unit 31. The counter unit 39 increases its counter status n by the figure “1” for every wash cycle performed. The limit counter status nG may, for example, be 3. This means that the comparison unit 41 generates the start signal SV every third wash cycle.
When there is a start signal SV, regardless of the wash program I, II or III selected by the user, the special cleaning program S is stored in the control unit 35. Therefore, without special selection by the customer, a special cleaning cycle is started which may differ compared to a wash program which can be selected by the user with regard to process temperatures and/or the flow guide or flow rate of the washing liquid.
Besides the number of wash cycles performed, the formation of films of dirt depends on additional factors, for instance the temperature profile of the respective wash program I, II, III used to perform the wash cycles or the level of soiling of the items to be washed.
In accordance with a modification of the first exemplary embodiment, the counter status n in the counter unit 39 can be increased not only as a function of the number of wash cycles already performed but also as a function of the aforementioned additional influencing variables. According to
In the aforementioned modification, when increasing the counter status n of the counter unit both the influencing variable “Number of wash cycles” and the influencing variable “Level of soiling of the items to be washed” are taken into account. The first and second count values may be different, resulting in both the influencing variables being weighted.
For example, a device cleaning method with a limit counter status nG of 3 is explained in the following. Only the number of wash cycles already performed should be recorded by the counter unit 39 without in addition also recording the type of wash program used, in other words, low-temperature program I, normal program II or high-temperature program, or other influencing variables.
Thus, for a first wash cycle the user selects the low-temperature program I using the actuating element 28 and stores it in the control unit 35, which performs the wash cycle with the low-temperature program I. At the same time the counter status n in the counter unit is moved from 0 to 1. In the subsequent wash cycle the user can, for example, select the normal program II by means of the actuating element 29. The counter unit 39 therefore increases its counter status n from 1 to 2. At the same time the storage unit 33 stores the normal program II in the control unit II in the control unit 35 so that the wash cycle takes place as a result of the normal program II selected by the user.
For a subsequent third wash cycle the user may select the high-temperature program III. The counter unit 39 therefore increases its counter status n from 2 to 3, as a result of which the comparison unit 41 generates the start signal SV and transmits it to the storage unit 33. In this case, the storage unit 33 does not store the high-temperature program III selected by the user in the control unit 35 but instead of this the special cleaning program S. The third wash cycle therefore takes place—without special selection by the user—by means of the special cleaning program S.
In
However, the control device 27 of the second exemplary embodiment has a differently implemented signal generating device 37. This is not equipped with a counter unit but only has the soiling sensor 43 which, for example, is provided as a deposit sensor for detecting greasy films of dirt in the base area of the washing container prone to soiling. The deposit sensor 43 together with the control unit 35 is integrated in a closed control loop in which the deposit sensor 43 detects an actual start signal and transmits it to the comparison unit 41. In the comparison unit 41 the detected actual start signal is compared to a limit value and if the limit value is exceeded, the start signal SV is generated and transmitted to the storage unit 33.
The control loop records the actual level of soiling in the hydraulic circuit of the dishwasher.
The temperature-time diagram in
When performing the special cleaning program S, in contrast to the low-temperature program I shown, the temperature of the washing liquid is increased to a cleaning temperature TRS, which is in a range between 65 and 75° C. In this way, the increased cleaning temperature TRS enables the breakdown of collected films of dirt during the circulation loop and their removal from the areas of the hydraulic circuit of the dishwasher prone to soiling. Alternatively and/or in addition to the increased cleaning temperature TRS during the heating phase ΔtH in the special cleaning program S, the upper spray arm 7 can be put out of operation. To this end the alternative water distributor 25 as per
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2008 040 647.3 | Jul 2008 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2009/059028 | 7/15/2009 | WO | 00 | 1/19/2011 |
