Method for identifying a degree of soiling of a cooking appliance interior

Abstract

A method for identifying a degree of soiling of an interior of a cooking appliance, in particular of the cooking chamber, during at least one of a cleaning operation and a cooking operation and a method for cleaning such a cooking appliance interior include determining at least one parameter of a liquid and a degree of soiling.

Claims

1. A method for identifying a degree of soiling of an interior of a cooking appliance during at least one of a cleaning operation and a cooking operation, comprising determining at least one parameter of a liquid over time and determining the degree of soiling of the interior from a change in the at least one parameter, wherein the at least one parameter is a physical variable which is determined via at least one sensor.

2. The method according to claim 1, wherein at least one first parameter of the at least one parameter is determined at a first point in time of the cleaning or cooking operation and at least one second parameter of the at least one parameter is determined at a second point in time of the cleaning or cooking operation, and the degree of soiling is determined from at least one of a change in and difference between the at least one first parameter and the at least one second parameter, and comparing at least one of a change in and difference between the at least one first parameter and the at least one second parameter with at least one predetermined or predeterminable limit value.

3. The method according to claim 1, wherein, in order to determine the degree of soiling at least one of: the at least one parameter is detected at a plurality of points in time, the progression of at least one parameter is detected over time, at least one of at least one maximum and at least one minimum of the progression of the at least one parameter is detected over time, at least on of the gradient and curvature of the progression of the at least one parameter is detected over time, and a regression analysis of the parameters is carried out.

4. The method according to claim 1, wherein at least one of the at least one sensor is installed in at least one of the cleaning path of the liquid and downstream of the cooking chamber, and an open- or closed-loop control device carries out at least one of the measurement and/or the evaluation of measured values obtained, wherein the open- or closed-loop control device preferably comprises the at least one sensor.

5. The method according to claim 1, wherein the time interval between two successive measurements is lengthened or shortened via the open- or closed-loop control device, as a function of at least one of the detected parameters, the detected progression of the parameters, the detected maximum of the progression of the parameters, the detected minimum of the progression of the parameters, at least one of the detected gradient and curvature of the progression of the parameters, and the regression analysis.

6. The method according to claim 1, wherein at least one of the degree of soiling and at least one, in particular previously carried out program, selected from a plurality of cleaning programs and/or cooking programs, is determined, in particular via the open- or closed-loop control device, as a function of at least one of the detected parameters, the detected progression of the parameters, the detected maximum of the progression of the parameters, the detected minimum of the progression of the parameters, at least one of the detected gradient and curvature of the progression of the parameters and the regression analysis.

7. The method according to claim 1, wherein the identified or determined degree of soiling is displayed at least temporarily, automatically or on request.

8. The method according to claim 1, wherein at least one of the at least one parameter is selected from at least one of turbidity, pH, conductivity, viscosity, color, refractive index, fluorescence, adsorption, emission and density of the washing liquor, and the at least one sensor is selected from at least one of an optical sensor, a turbidity sensor, a pH sensor, a conductivity sensor, a viscosity sensor, a color sensor, a sensor for measuring refractive index, a fluorescence sensor, a sensor for measuring adsorption and/or emission and a density sensor.

9. The method according to claim 6, wherein the minimum of the time progression of parameters for turbidity is detected or determined and, on the basis of the parameter at the minimum, the degree of soiling is determined, wherein the parameter at the minimum is smaller at a greater degree of soiling.

10. The method according to claim 1, wherein as a function of the identified or determined degree of soiling, at least one of an ongoing cleaning operation is adapted, at least one of a suggestion for and a modification to a future cleaning program is determined, at least one characteristic variable of at least one of a previous and the current cooking operation is determined, and a user behavior is determined.

11. The method according to claim 1, wherein the liquid selected is a washing liquor during a cleaning operation or a water reserve upstream from an outlet of the cooking appliance during a cooking operation.

12. The method according to claim 1, wherein at least one of the parameters of the cleaning operation is paused during a cleaning operation prior to determination.

13. The method according to claim 12, wherein the duration of the pause in at least one of the cleaning operation and the timing of the pause in the cleaning operation is determined, in particular via the open- or closed-loop control device, as a function of at least one of the detected parameters, the detected progression of the parameters, the detected maximum of the progression of the parameters, the detected minimum of the progression of the parameters, at least one of the detected gradient and curvature of the progression of the parameters, and the regression analysis.

14. A cooking appliance for cooking food items in a cooking chamber; comprising at least one sensor; and an open- or closed-loop control device for carrying out a method according to claim 1.

15. The cooking appliance according to claim 14, wherein the cooking appliance is self-learning.

16. The cooking appliance according to claim 14, further comprising an output device, comprising a display means, for the detected degree of soiling.

17. The cooking appliance according to claim 14, wherein the sensor is arranged downstream of the cooking chamber with the liquid flowing therearound.

18. The cooking appliance according to claim 14, wherein the cooking chamber is connected, with interposition of a strainer, to at least one of a condenser and a cleaning tank, and the sensor is arranged in at least one of the condenser and/or cleaning tank.

19. The cooking appliance according to claim 14, wherein at least one of the condenser and cleaning tank is connected to at least one of an at least temporarily closable outlet and to an at least temporarily closable return line to the cooking chamber.

20. The cooking appliance according to claim 19, wherein at least one of the outlet is temporarily closable via a pump or a valve, and the return line is connected to at least one of a pump and a valve.

21. The cooking appliance according to claim 20, wherein the sensor is arranged in the water reserve provided by at least one of a sump of the pump of the outlet and of the pump of the return line.

22. The cooking appliance according to claim 17, wherein the sensor is arranged in the water reserve between the cooking chamber and the outlet from the cooking appliance.

23. The cooking appliance according to claim 17, wherein the water level of the water reserve is adjustable via at least one of an open- or closed-loop control device in operative connection with the pump of the outlet, the pump, the return line, and a shut-off device.

24. A method for cleaning a cooking appliance interior, comprising the following steps after a start of a cleaning operation having at least one cleaning phase: introducing a washing liquor into the cooking appliance interior and starting the at least one cleaning phase using one or more cleaning parameters; determining at least one first parameter TS.sub.1 of the washing liquor at a first point in time t.sub.1 of the cleaning operation and determining at least one second parameter TS.sub.2 of the washing liquor at a second point in time t.sub.2 of the cleaning operation; and determining a degree of cleaning of the cooking appliance interior from a change in the parameters; wherein, depending on the change in the parameters, at least one of the steps are repeated and at least one of the cleaning parameters is adapted or the at least one cleaning phase is terminated.

25. The method according to claim 24, wherein, for determining the degree of cleaning of the cooking appliance interior at a plurality of points in time, at least one of the at least one parameter is detected, the progression of the parameters over time is detected, at least one of at least one maximum and at least one minimum of the progression of the parameters over time is detected, at least one of the gradient and curvature of the progression of the parameters is detected over time, and a regression analysis of the parameters is carried out.

26. The method according to claim 24, wherein the degree of cleaning of the cooking appliance interior is determined from the change in and/or difference between the first parameter relative to the second parameter, TS.sub.1=TS.sub.2TS.sub.1, and by comparing the change in and/or difference between the parameters with at least one known limit value TS.sub.limit.

27. The method according to claim 24, wherein at least one of in that initial cleaning parameters are determined by determining at least one parameter TS.sub.0 at a point in time t.sub.0, and in that initial cleaning parameters are determined by manual selection of a cleaning program.

28. The method according to claim 24, wherein the at least one parameter is a physical variable which is at least one of determined via at least one sensor and selected from at least one of the turbidity, pH, electrical conductivity, viscosity, color, refractive index, fluorescence, adsorption, emission and density of the washing liquor.

29. The method according to claim 28, wherein at least one of the at least one sensor is installed in at least one of the cleaning path of the washing liquor, the control box, the pump sump, the cooking chamber, the cleaning product box and a pipe of the cooking appliance, an open- or closed-loop control device carries out at least one of the measurement and the evaluation of the measured values obtained, wherein the open- or closed-loop control device preferably comprises the at least one sensor, and in that the at least one sensor is selected as an optical sensor, a turbidity sensor, a pH sensor, a conductivity sensor, a viscosity sensor, a color sensor, a sensor for measuring refractive index, a fluorescence sensor, a sensor for measuring adsorption and emission, and a density sensor.

30. The method according to claim 24, wherein the first point in time t.sub.1 is selected during the at least one cleaning phase and the second point in time t.sub.2 after the at least one cleaning phase, wherein the cleaning operation is preferably terminated when the at least one limit value is reached.

31. The method according to claim 24, wherein at least one of as a function of the identified or determined degree of cleaning, at least one of at least one cleaning parameter, at least one limit value, and at least one time interval between the determination of two parameters is at least one of determined, stored and displayed for at least one of at least one subsequent cleaning phase of the cleaning operation and a future cleaning operation, in that, as a function of the identified or determined degree of cleaning, at least one cleaning parameter of at least one previous cleaning phase of the cleaning operation is at least one of determined, stored and displayed, in that, as a function of the identified or determined degree of cleaning, at least one characteristic variable of at least one previous cooking operation is at least one of determined, stored and displayed, and as a function of the identified or determined degree of cleaning, a user behavior is at least one of determined, stored and displayed.

32. The method according to claim 24, wherein the at least one or plurality of cleaning parameters are selected from at least one of the duration of the at least one cleaning phase, the temperature during the at least one cleaning phase, the speed of circulation of the cleaning agent, the acceleration of circulation of the cleaning agent, the chemistry of the cleaning agent, the quantity of cleaning agent, the quantity of washing medium, in particular water, and a combination thereof.

33. The method according to claim 24, wherein at least one of the at least one cleaning phase is selected from at least one of a cleaning product phase, a rinse aid phase and a descaler phase, and the chemistry of the cleaning agent is selected from at least one of a cleaning product, a rinse aid and a descaler.

34. A cooking appliance for cooking food items comprising a cleaning device, at least one sensor and an open- or closed-loop control device for carrying out a method according to claim 24.

35. The cooking appliance according to claim 34, wherein at least one of the cooking appliance comprises at least one dispenser for the cleaning agent, the cooking appliance further comprises the washing medium, and the cooking appliance is self-learning.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0062] FIG. 1 illustrates a parameter progression, in the form of a turbidity change profile (stated in [V]) of a washing liquor in a cooking chamber of a cooking appliance over time;

[0063] FIG. 2 illustrates the proportion and size of particles in a washing liquor over the course of the cleaning phase;

[0064] FIG. 3 illustrates a parameter progression over a complete cleaning method, including rinsing phase and drying operation;

[0065] FIG. 4 illustrates parameter progressions for light, moderate and severe soiling and cleaning with and without the addition of cleaning agent; and

[0066] FIG. 5 illustrates a partially sectional view through a cooking appliance;

[0067] FIG. 6 illustrates a parameter progression in the form of a turbidity change profile of a washing liquor in a cooking chamber of a cooking appliance;

[0068] FIG. 7 illustrates a portion of an automated cleaning method;

[0069] FIG. 8 illustrates a complete cleaning method without a subsequent rinsing phase;

[0070] FIG. 9 illustrates parameter progressions for cleaning methods without use of cleaning agents.

DETAILED DESCRIPTION

[0071] The method is described by way of example on the basis of the determination of turbidity values of the washing liquor, wherein the method can be carried out in a similar manner for any other of the above-stated parameters or any combination of parameters. When a turbidity sensor is used, a low parameter for example means high turbidity, since voltage values are detected which are lower, the smaller the quantity of light is that passes through the washing liquor and impinges on a sensor due to the turbidity of the washing liquor.

[0072] After the start of a cleaning program and introduction of washing liquor into the cooking chamber of a cooking appliance, a cleaning phase is started which uses the cleaning parameters, such as for example a defined temperature with a predetermined cleaning agent. FIG. 1 shows by way of example a possible parameter progression over time (cleaning progress). At the beginning of cleaning, the turbidity in the washing liquor may for example increase sharply. Thereafter, turbidity does not increase any further, but instead declines. This is for example because, without being limited thereto, a very large number of particles which are detached from the cooking chamber wall are present in the washing liquor at the beginning of cleaning. These numerous particles cause severe diffraction of the light. These first turbidity values provide direct information about how severely the cooking appliance interior is soiled. In the case of slight soiling, the decline in the curve is correspondingly low, while the decline is greater in the case of severe soiling and thus severe turbidity of the washing liquor. Turbidity then falls during cleaning, as the appliance thus becomes cleaner, since more soil particles dissolve in the washing liquor than new ones are detached in the cooking chamber. The turbidity curve rises as a consequence.

[0073] The proportion of particles in the washing liquor and thus the degree of turbidity can be taken from FIG. 2, wherein it is apparent that the particles become ever smaller over the course of time and ultimately completely dissolve, such that turbidity declines or, ideally, disappears.

[0074] As is apparent from progression 1 in FIG. 1, in a cooking appliance with severe soiling, the curve declines rapidly right at the beginning of measurement, specifically to a minimum M.sub.1, while in the case of severe soiling the further progression can be observed to continue virtually horizontal with a high level of turbidity. In the case of slight soiling, the curve likewise initially declines, as is apparent from progression 2 in FIG. 1 with the minimum M.sub.2, but not as low as in a cooking appliance with severe soiling, since less turbidity of the washing liquor is present. In other words, M.sub.2 is greater than M.sub.i. In progression 2, after the minimum M.sub.2, a distinct upward rise is apparent, since turbidity declines relatively rapidly as a consequence of the reducing degree of soiling. In the case of very slight soiling, as indicated with progression 3 in FIG. 1, after a first decline of the curve to a minimum M.sub.3, the progression becomes virtually horizontal with a relatively low level of turbidity. Minimum M.sub.3 is higher than minimum M.sub.2.

[0075] The degree of soiling can thus in particular be inferred from the minimum of the turbidity value progression. The lower the detected voltage value at the minimum during the turbidity value progression, the greater is the degree of soiling.

[0076] FIG. 3 shows the curve progression for further cleaning tests. It is apparent that at the beginning of a cleaning phase (2) the measured value for turbidity, i.e. voltage, declines sharply, which correlates with severe soiling or for example indicates that the appliance has not previously been cleaned or not adequately cleaned. Over the course of the cleaning operation, the measured value rises due to the reduction in the degree of soiling. At the end of the cleaning phase (2), the determined parameter is below a defined limit value and the cleaning phase (2) is terminated such that a new phase (3) can follow. Phase (3) is a rinsing phase with a peak which is characteristic for this phase and which indicates that a rinse aid has been added. The final phase (4) shown is a drying operation.

[0077] FIG. 4 shows typical parameter curve progressions which are indicative of slight, moderate or severe soiling. The decline differs in extent depending on the soiling the lower the decline extends, the greater the soiling. The curve progression is likewise dependent on the tenacity of the soiling and/or the quantity of soiling and is characteristic of the respective state. The curve progressions of FIG. 4 also show that no rinsing has been carried out, since there is no peak which is characteristic thereof

[0078] FIG. 5 shows a cooking appliance 1 with its cooking chamber 10 which is connected to a condenser 20 and cleaning tank 24. The cooking chamber 10 is here connected to the condenser 20 via a drain 12, in which a strainer 14 for separating coarse soiling is arranged. The strainer 14 extends into the condenser 20 and the connection to the cleaning tank 24 is provided via a connecting line 22. The cleaning tank 24 is connected to an outlet 30 via a wastewater pump 32 and to a return line 40 via a circulating pump 42.

[0079] During a cleaning method, washing liquor 26, which can be introduced into the cleaning tank 24 with a determined water level 27, is conveyed from the cleaning tank 24 into the cooking chamber 10 by means of the circulating pump 42 in order to carry out cleaning. The washing liquor flows out of the cooking chamber 10, passing through the strainer 14 and back into the cleaning tank 24. The washing liquor 26 is thus circulated.

[0080] During a cooking method, instead of the washing liquor 26 shown in FIG. 5, a pump sump is located upstream of the outlet to the pumps 32, 42. Juices which arise during boiling, roasting, grilling or the like here flow out from the cooking chamber 10 via the strainer 14 into the pump sump.

[0081] A turbidity sensor 28 is arranged in the cleaning tank 24. The position of the turbidity sensor 28 is selected such that, during a cleaning method, the washing liquor 26 flows effectively around it and, that during a cooking method, a location below the water level 27 of the pump sump is ensured. The turbidity sensor 28 need not necessarily be fastened for this purpose to the bottom of the cleaning tank 24 but can also be provided in a wall. The position in the bottom shown in FIG. 5 is particularly favorable for the construction geometries shown.

[0082] The water level 27 can be controlled by means of the wastewater pump 32, or alternatively via an outlet valve (e.g. ball valve), a defined drain orifice or the like.

[0083] In the cooking appliance 1 of FIG. 5, it is possible to determine a degree of soiling in particular of the cooking chamber 10 via the turbidity sensor 28 not only during a cleaning operation, but also during a cooking operation. It is essential to this end for the turbidity sensor 28 to be located in a water reserve, either in the form of a washing liquor or a pump sump, downstream of the cooking chamber 10, which generally means below the cooking chamber 10, as is also indicated in FIG. 5.

[0084] If turbidity values are detected for example during a cooking method, it is possible to draw a conclusion therefrom about the soiling of the cooking chamber 10 which is dependent on the quantity and nature of the foodstuff being cooked. On the basis of the determined degree of soiling, it is then in turn possible to determine a suitable cleaning method which is to proceed later. This cleaning method can be output as a suggested cleaning program, either on a display means on the cooking appliance 1 or on a central control console of a kitchen network into which the cooking appliance can be integrated. The display may for example appear after completion of the cooking operation automatically or only on request.

[0085] In a further embodiment, after introduction of the washing liquor into the cooking chamber of a cooking appliance, in which foodstuffs can in particular be exposed to hot air, steam and/or microwaves, a cleaning operation is started either automatically after determination of a parameter T.sub.0 at a point in time t.sub.0 or by selection of a cleaning program by a user. Automatic determination or manual selection of the cleaning program also results in the selection of cleaning parameters, such as for example a predetermined temperature and a cleaning product chemistry to be used. If the cleaning program comprises a plurality of cleaning phases, the cleaning parameters are provisionally selected for all cleaning phases.

[0086] FIG. 6 shows by way of example a possible parameter progression over time, from which the cleaning progress can be inferred. At the beginning of cleaning, the turbidity in the washing liquor may for example increase sharply. Thereafter, turbidity does not increase any further, but instead declines. This is for example because, without being limited thereto, a very large number of particles which are detached from the cooking chamber wall are present in the washing liquor at the beginning of cleaning. These numerous particles cause severe diffraction of the light. These first values for turbidity provide direct information about how severely the cooking appliance interior is soiled. In the case of slight soiling, the decline in the curve is correspondingly low, while the decline is greater in the case of severe soiling and thus severe turbidity of the washing liquor. Turbidity falls during cleaning, as the appliance becomes cleaner, since more soil particles dissolve in the washing liquor than new ones are detached in the cooking chamber. The turbidity curve rises as a consequence. The proportion of particles in the washing liquor and thus the degree of turbidity can be inferred for example from FIG. 7, wherein it is apparent that the particles become ever smaller over the course of time and ultimately completely dissolve, and thus turbidity declines or, ideally, disappears.

[0087] Relatively shortly after the start for example of a first cleaning phase, a first turbidity value TS.sub.1 is determined at a first point in time t.sub.1 by means of one or more sensor(s) present in the cooking chamber. Then, at a predetermined second point in time t.sub.2, the current turbidity of the washing liquor is determined, thus a second turbidity value TS.sub.2 is determined. On the basis of the two turbidity values, a first difference is then determined: TS.sub.1=TS.sub.2TS.sub.1. The difference value determined in this manner is then compared with a predetermined first limit value. If, for example, the first limit value is exceeded, i.e. TS.sub.1>TS.sub.limit, a second cleaning phase is started. After an identical time interval has elapsed, a third turbidity parameter TS.sub.3 is detected and a second difference, i.e. TS.sub.2=TS.sub.3TS.sub.2, determined and compared with the first or a second limit value. Should the limit value again be exceeded, i.e. TS.sub.2>TS.sub.limit, a third cleaning phase begins automatically. In the example in FIG. 6, this procedure is repeated another three times. The cleaning phase which starts over each time can be carried out unchanged or with changed cleaning parameters, such as for example a changed temperature. When the difference finally undercuts the limit value, i.e. TS<TS.sub.limit, the cleaning operation is terminated since the appliance has achieved the desired cleanliness. It is likewise possible to use the measured values obtained to generate a measurement curve, for example by a regression analysis, as shown in FIG. 6. On the basis of the curvature and/or gradient of the curve, it is possible to establish when the cooking appliance is clean and/or which cleaning parameters should be used in subsequent cleaning phases.

[0088] Selection of the cleaning program is non-critical in a method because the cleaning phases of the particular cleaning operation which has been started are automatically adapted. This enables the provision of a cooking appliance with only one cleaning program, which is preferably an environmentally friendly eco program which for example requires additional cleaning agent and/or elevated temperatures only in the case of a respective degree of soiling. In one embodiment, the cooking appliance itself determines the cleaning program, i.e. the cleaning parameters, by ascertaining the initial turbidity value.

[0089] In addition, the cooking appliance may also be self-learning, since it can store changed cleaning parameters for future cleaning operations. A linkage to cooking programs can also be made by correlating the detected degree of soiling with the cooking program(s) which has/have previously been run.

[0090] FIG. 7 shows a portion of one possible procedure of the cleaning method. At the beginning, a first turbidity value (TS.sub.1) is determined and evaluated. The cleaning phase is started, and in particular determined by evaluation of the turbidity value TS.sub.1. At the end of the cleaning phase (in this case: after 8 min), a second turbidity value TS.sub.2 is determined. By calculating the difference and comparing the value obtained with a limit value, it is possible to determine whether a desired degree of cleaning has or has not been achieved. Should the desired degree of cleaning not have been reached, the value TS.sub.2 is stored as a new value TS.sub.1 and the cleaning phase starts over again.

[0091] FIG. 8 shows the complete cleaning method, in which introductory steps prior to the method steps described in relation to FIG. 7 are described for carrying out a component test, steaming the cooking chamber, a brief circulation phase (in this case 60 seconds) and a pause of the circulating pump. As is additionally indicated in FIG. 8, the cleaning method is terminated when the limit value is reached by rinsing the appliance , for example in a rinsing phase.

[0092] FIG. 9 finally shows two typical curve progressions for moderate soiling and light soiling, in each case by cleaning without using chemicals, i.e. without a cleaning agent. The characteristic progression of the cleaning curve reveals that no cleaning agent has been used. The initial values are not reached again at the end of cleaning because soiling still remains in the cooking appliance. The characteristic peak for the rinsing phase (see FIG. 3) is only very small, see arrow in FIG. 9.

[0093] The features of the invention disclosed in the above description, in the claims and in the drawings may be of significance for implementation of the invention in its various embodiments either individually or in any desired combination.

LIST OF REFERENCE NUMERALS

[0094] 1 Cooking appliance

[0095] 10 Cooking chamber

[0096] 12 Drain

[0097] 14 Strainer

[0098] 16 Fan wheel

[0099] 20 Condenser

[0100] 22 Connecting line

[0101] 24 Cleaning tank

[0102] 26 Washing liquor

[0103] 27 Water level

[0104] 28 Turbidity sensor

[0105] 30 Outlet

[0106] 32 Wastewater pump

[0107] 40 Return line

[0108] 42 Circulating pump