EP2466209A2 - Method for determining different reasons for the failure of a steam cooker - Google Patents

Abstract

The method involves determination of duration by activation of current flow by the heat element up till an interruption of the current flow by the heat element. A cause of malfunction (U1) is determined when the determined duration (300) has a value, which lied in a time interval (Z1). Another cause of malfunctioning (U2) is determined when the determined duration has a value, which lies in another time interval (Z2) different from the former time interval. An independent claim is also included for a steamer.

Description

The present invention relates to a method for determining a malfunction cause of a steam cooking appliance according to the preamble of claim 1.

Modern steam cooking appliances have an evaporator bowl with a radiator that heats water in the evaporator bowl. In this heater or heating element of the evaporator shell of Dampfgargeräts two protective protectors are mounted according to a VDE standard, which trigger in case of overheating of the heating element due to malfunction of Dampfgargeräts and interrupt the power supply to the heating element to prevent damage to the Dampfgargeräts. It is often not clear to a user which of a number of possible errors has just occurred which should be remedied for further operation of the steam cooking appliance.

It is the object of the present invention to provide an improvement in ease of use for a steam cooker as well as an improved steam cooker.

This object is achieved by a method according to claim 1 and the steam cooking appliance according to claim 12. Advantageous embodiments emerge from the respective subclaims and the following description.

The present invention provides a method for determining different malfunction causes of a steam cooker having a heating element for heating water in an evaporator dish. Furthermore, the method comprises a step of detecting a period of time from activating a current flow through the heating element to interrupting the current flow through the heating element. Finally, the method includes a step of determining a first malfunction cause when the detected period of time has a value that is within a first time interval. Alternatively or additionally, a second malfunction cause is determined in the step of determining if the detected time duration has a value which lies in a second time interval different from the first time interval.

The present invention is based on the recognition that by evaluating the time periods from the switching on of the current flow through the heating element to the interruption of the current flow through the heating element, it is very easy to make a distinction between different fault causes. This exploits the fact that due to different causes of the fault the heating element also heats up or overheats so that the time from switching on the current flow through the heating element until the current flow through the heating element makes it possible to draw conclusions about the cause of the malfunction that has occurred. Such an evaluation of the detected time span can be realized with technically very simple means.

According to an embodiment of the present invention, in the step of determining, the first malfunction cause may be a dry running of the steam cooking appliance. The cause of the malfunction "dry run" can be an operating state of the steam cooking appliance in which the appliance is operated without water in the evaporator bowl. The dry run may be a state of the steam cooker that can be detected in a relatively short period of time after the current flow through the heating element is activated. Such an embodiment of the present invention offers the advantage of fast and reliable detection of an error that often occurs during operation.

It is advantageous if, in the step of determining, as the first time interval, a time interval is used which comprises values which lie in an interval of 1 second to 20 seconds. Such an embodiment of the present invention has the advantage that when a current flows through the heating element can be detected very quickly and clearly that no more water is in the evaporator shell.

According to another embodiment of the present invention, in the step of determining, the second malfunction cause may constitute calcification of the evaporator shell. Such an embodiment of the present invention offers the advantage that a further more frequent cause of error can be easily recognized by the method.

Hereafter, in the step of determining as the second time interval, a time interval may be used which comprises values which are greater than the values of the first time interval, in particular values which lie in an interval of more than 20 seconds to 60 seconds. It is exploited that a calcification of the evaporator shell makes it difficult to transfer heat from the heating element to the water, so that while still a heating of the water is possible, but this heating takes place too slowly. This leads to overheating of the heating element only after a certain delay. Such an embodiment of the present invention offers the advantage that the cause of the calcification can also be recognized technically very easily in an indirect way by detecting the overheating of the heating element after a certain period of time.

Additionally, the method may include a step of verifying a possible calcification of the evaporator bowl of the steam cooker. In this case, a calcification can be detected if a maximum allowable current flows through the heating element during a test period and the current flow through the heating element is interrupted within this test period. In this way, a calcification of the evaporator shell can be advantageously already determined before it is so pronounced that it leads to a forced shutdown of the current flow through the heating element by means of a protective protector.

Also, in the step of determining, the method may further determine a third malfunction cause if the detected period of time has a value smaller than the values of the first time interval. Such an embodiment of the present invention offers the advantage that at least one further cause of malfunction of the steam cooking appliance is possible by using the same procedure as in determining the first and second malfunction cause. This expands the possibilities for the use of the approach described above for the detection of malfunction causes of a steam cooker.

For example, in the step of determining, the third malfunction cause may constitute a failure of a power supply to the heating element, a defect of the heating element, a defect of a circuit breaker of the heating element or a defect of a thermal bridge between the heating element and the evaporator shell. Such an embodiment of the present invention offers the advantage that even when switching on or very short after switching on a defect of Dampfgargerätes itself or the heating element of Dampfgargerätes can be reliably detected as the cause of the malfunction of Dampfgargerätes.

According to a further embodiment, a further malfunction cause can be determined in the step of determining if the current flow through the heating element was interrupted, subsequently an activation signal was output to a pump connected between the evaporator shell and a water tank, then the current flow through the heating element was switched on again and the current flow is then interrupted after a re-detected period of time having a value which is in the first time interval. Such an embodiment of the present invention offers the advantage that empty cooking (i.e., a malfunction due to lack of water in the water tank) can be established beyond doubt and without an additional sensor in the water tank. The detection of such a malfunction cause would otherwise be possible only with much greater technical effort or not at all, since the error of emptying can be set at any time during operation of the Dampfgargeräts.

According to another embodiment of the present invention, in the step of detecting, the time period determined by interrupting the flow of current due to opening of a circuit breaker connected in series with the heating element may be detected. Such an embodiment of the present invention is based on an existing monitoring capability of the circuit breaker for the heating element, in which case no malfunction cause can be detected according to the present approach, if the interruption of the current flow is not made by a response of the circuit breaker. Such an embodiment of the present invention offers the advantage of a plausibility check of the identified malfunction cause.

According to a further embodiment, in the step of determining the first or second malfunction cause can be transmitted to a warning device of the steam cooking appliance, which outputs a signal corresponding to the determined malfunction cause acoustically and / or optically. Advantageously, such a user of Dampfgargeräts receives the opportunity to quickly recognize the cause of the currently present error of Dampfgargerätes and decide on the basis of the transmission of appropriate information, whether a customer service application is required or he himself has the opportunity to restore the function of the steam cooking appliance.

The present invention further provides a steamer with an evaporator bowl having a heating element configured to heat water in the evaporator bowl, and at least one circuit breaker configured to interrupt a flow of current through the heating element. Further, the steam cooker includes an error monitor configured to detect a time period between turning on a current flow through the heating element and interrupting current flow through the heating element and determining a first malfunction cause of the steam cooking appliance when the detected duration has a value, which is in a first time interval and / or to determine a second malfunction cause of the steam cooking appliance, if the detected time duration has a value which is in a different from the first time interval second time interval. In particular, an oven may be equipped with such a steam cooker. Such embodiments of the present invention also provide a way of quickly, effectively, and inexpensively detecting different causes of malfunction of the steam cooker.

Fig. 1

eine perspektivische Ansicht eines Haushaltsgeräts, in dem das Verfahren gemäß einem Ausführungsbeispiel durchgeführt wird und das einen Backofen mit einem Dampfgargerät gemäß einem Ausführungsbeispiel der vorliegenden Erfindung aufweist;

Fig. 2

eine schematische Darstellung eines Dampfgargeräts gemäß einem Ausführungsbeispiel der vorliegenden Erfindung;

Fig. 3

ein Zeitdiagramm, das eine Zuordnung von unterschiedlichen Fehfunktionsursachen zu verschiedenen erfassen Zeitdauern gemäß dem Ausführungsbeispiel der vorliegenden Erfindung wiedergibt; und

Fig. 4

ein Ablaufdiagramm eines Verfahrens gemäß einem Ausführungsbeispiel der vorliegenden Erfindung.

Advantageous embodiments of the present invention will be explained in more detail with reference to the accompanying drawings. Show it:

Fig. 1

a perspective view of a household appliance, in which the method is carried out according to an embodiment and having an oven with a steam cooker according to an embodiment of the present invention;

Fig. 2

a schematic representation of a Dampfgargeräts according to an embodiment of the present invention;

Fig. 3

FIG. 3 is a timing diagram showing an association of different cause of malfunction at different detected time periods according to the embodiment of the present invention; FIG. and

Fig. 4

a flowchart of a method according to an embodiment of the present invention.

The same or similar elements may be indicated in the figures by the same or similar reference numerals, wherein a repeated description is omitted. Furthermore, the invention is explained in the following description using different dimensions and dimensions, wherein the invention is not limited to these dimensions and dimensions to understand.

Fig. 1 shows a perspective view of a household appliance 100. The household appliance 100 has a hob 110 with four cooking zones 115 and an oven 120, wherein of the cooking zones for clarity, only one is provided with a reference numeral. The oven 120 has a oven door 125, a door handle 130, a viewing window 135, a blow-out gap 140 and a front panel 145. The oven door 125 closes a cooking space inside the oven 120 and may be formed as a hinged door or a pull-out door. The viewing window 135 forms part of the oven door 125 and may be composed of one or more panes of glass. The door handle 130 is disposed in an upper portion of the oven door 125 and extends parallel to an upper door panel. The blow-out gap is located between the upper door panel and the front panel 145. The front panel 145 has a control panel 150 that includes controls 155. The controls 155 are operable by a user of the home appliance to control functions of the oven 120. The oven 120 has the invention described in more detail below a Dampfgarvorrichtung, which is also drawn as Dampfgargerät. The steamer is in Fig. 1 but not shown.

In operation of the embodiment of the present invention as more fully described in the following description, substantially four fault situations may arise which result in a response of the protective protectors or circuit breakers (ie interruption of current flow through the heating element), namely dry running of the steam cooker emptying the steamer, calcifying the steamer bowl, resulting in poorer heat transfer between the heating element and the evaporator bowl, and a defect in the power supply or heating element or heat coupling between the heating element and the evaporator bowl.

Fig. 2 shows a schematic representation of a Dampfgargeräts 200 according to an embodiment of the present invention. The Dampfgargerät 200 is part of the oven 120 and allows the loading of a cooking chamber 205 with steam for cooking food, which were introduced into the cooking chamber 205. Shown are a water tank 210, a pumping device 220, a heating element 230, a protector or circuit breaker 240 with special functions, an evaporator shell 250, a controller 260 and a temperature sensor 270 which is arranged in the cooking chamber 205 or monitors a temperature of the cooking chamber 205. Although this is in the illustration in Fig. 2 is not shown, the Dampfgargeräts 200 may include a protector or circuit breaker 240 in series connected further protector, which also monitors a temperature of the heating element 230 and terminates a current flow through the heating element 230 when the heating element 230 has become too hot.

The Dampfgargerät 200 is according to the embodiment in the oven 120 of associated with Fig. 1 integrated household appliance 100 integrated. Here, the water tank 210, the pumping device 220, the heating element 230, the circuit breaker 240, the evaporator shell 250 and the control unit 260 are arranged outside of the cooking chamber 205. As shown Fig. 2 the evaporator shell 250 may be arranged below the cooking chamber 205, wherein a bottom of the cooking chamber 205 is provided with an opening or a plurality of openings so that steam generated in the evaporator shell 250 can flow into the cooking chamber 205 in order to cook food placed there. The temperature sensor 270 (which is designed, for example, as a PT1000 sensor) can be arranged so that it protrudes into the cooking chamber 205 in order to measure a prevailing cooking chamber temperature there.

As shown in Fig. 2 For example, the control unit 260 has electronics and a warning or display device 275 or a display which is connected to the control or fault detection monitoring device 260, for example via a system bus, or integrated into the control device 260. The controller 260 is configured to measure a current flowing through the heater 230 and to visually and / or audibly indicate a detected malfunction cause of the steam cooker 200, for example via the warning or indicator 275, which is good from outside the domestic appliance 100 for an operator of the home appliance is perceptible. Further, the controller 260 is via a first electrical line 280 to the radiator 240 and the circuit breaker 240 connected. Via a second electrical line 285, the control unit 260 is connected to the temperature sensor 270. The heating element 230 is arranged below the evaporator shell 250 and is heated by means of a current flow 287 through the heating element 230. The voltage in a circuit of the first line 280 is about 230V. The heat generated in the heating element 230 is transferred via a thermal bridge 288, for example using a thermal paste, between the heating element 230 and the evaporator shell 250 through the evaporator shell 250 to water in the evaporator shell 250 so as to produce the water vapor required for the cooking process.

In the circuit comprising the heating element 230, the protector or circuit breaker 240 is integrated, which interrupts a current flow through the heating element 230, if it has heated up too much. Via a third electrical line 290, the control unit 260 is connected to the pump 220 or a solenoid valve. Via the third line 290, the control unit 260 outputs a filling signal 292 to the pump 220 in the presence of predetermined conditions. In response to the fill signal 292, the pump 220 conveys water from the water tank 210 into the evaporator shell 250 via a conduit 295.

Fig. 3 FIG. 12 is a timing diagram showing an association of different cause of malfunctions at different detected time periods according to the embodiment of the present invention, the illustration of FIG Fig. 3 merely serves to illustrate the causal relationships and is therefore not to scale. First, by the controller 260, a current flow 287 through the heating element 230 off Fig. 2 started at time 0s and a time period 300 measured until the current flow 287 is interrupted by the heating element 230 due to a response of the circuit breaker 240. A first malfunction or a first malfunction cause "dry run", hereinafter referred to as U1, can be identified or measured in the starting phase by a very short heating-up time of the heating element 230 until the current interruption by the protector 240. This error cause U1 can be detected when a measured value for the time duration 300 lies in a first time window Z1, which comprises values that are less than 20 seconds. It can be considered that within a very small and early time interval Z3 of, for example, zero seconds to one second after the start of the current flow 287 through the heating element 230 this is practically not heated enough so that water could evaporate. Thus, the cause of the error "dry running" in this early time interval Z3 can not yet be determined unambiguously. In particular, therefore, the malfunction cause U1 ("dry-running") can be detected when the detected time period 300 in the first time window Z1 is from 1 second to 20 seconds.

An error case or malfunction cause "shell calcified" (hereinafter referred to by the reference symbol U2) is identifiable by triggering the circuit breaker 240 (or one of several circuit breakers) if this triggering is in a second time window Z2, the values from 20 to 60 seconds from the start of the current flow 287 by the heating element 230 includes. Although water is present in the shell 250, due to a lime deposit acting as an insulation layer in the shell 250, the thermal transition is degraded so that accumulation heat on the heating element 230 slowly heats it so that the circuit breaker 240 trips in said second time interval Z2.

For early detection of a calcified shell, a special test routine can be activated automatically, in which case a display "descaling / cleaning dish" is displayed on a display of the warning device 275, if such cleaning or descaling appears advisable. If the test routine should lead to the result that a descaling or cleaning of the evaporator shell 250 is not required, the heating element 230 is supplied with a maximum allowable power for the heating element 230 over a test period T3 of 60 seconds. This means that for a period of 60 seconds, the maximum permissible current flow for the heating element 230 is passed through the heating element 230, wherein the circuit breaker or switches 240 should not trigger. If the circuit breaker or switches 240 are triggered, an increased calcification of the evaporator shell 250 must be assumed and a cleaning or descaling of the evaporator shell 250 should be carried out. To display this information to the operator of Dampfgargerätes appears on the warning device 275, for example, a display "Descale bowl / clean".

An error or malfunction cause "empty cooking" (in Fig. 3 indicated by the reference symbol U3) can occur at any time during the cooking time. Has during normal operation, ie after a period of 60 seconds after switching on of the current flow 287 is triggered by the heating element 230 one or more circuit breaker 240, the filling signal 292 is automatically sent to a solenoid valve or the pump 220 to fill the evaporator shell 250 with water from the Wasertank 210. A memory for the detected time period is reset and after filling or alleged successful filling of the evaporator shell 250 with water from the water tank 210, a current flow 287 is again initiated by the heating element 230. Again, a period of time 300 for interrupting the flow of current 287 is measured by triggering of the circuit breaker or switches 240. If, on continuation of the cooking process, an error "dry run" occurs (ie the circuit breaker or triggers within the previously described time window Z1), there is definitely no water in the water tank 210. For example, a corresponding signal "no water present → fill the water tank" is then output via the display unit of the warning device 275 of the steam cooking appliance to the customer or user of the steam cooking appliance 200. Visually, the evaporator shell 250 can also be identified as dry in this case of error.

An error or malfunction cause "no current flow → customer service" (in Fig. 3 indicated by the reference numeral U4) is characterized by no heating, so no current flow 287 through the heating element 230, from. The cause here is a defect in the electronics or the power supply to the radiator 230 or the circuit breaker 240. A signal for the indication "malfunction / customer service" is output in a display of the warning device 275 of the steamer 200. This fault U4 can be detected immediately after the beginning of the time measurement, namely, in that then no current flows through the heating element 230. In this case, by starting and immediately thereafter stopping the counter, the time duration 300, for example less than 1 second, can be measured.

In a possible further development of the approach presented here, the PT1000 sensor 270 can monitor the cooking space 205 of the steam cooking appliance 200, whereby additional additional information, for example a started or completed heating phase, is interrogated by this sensor 270 and additionally used in determining the cause of the fault can be. For example, this additional information can be used to detect this cause U3 in the detection of the malfunction cause U3 ("empty cooking") even if the one or more circuit breakers 240 trigger in the time window Z3, which extends from 0 seconds to 1 second. In this case, before steaming the evaporator tray 250 with water from the water tank 210, the steam cooker 200 has already functioned correctly, so that when the cooking space 205 is hot, the cause of empty cooking is much more likely than a failure of the heating element 230, the circuit breaker 240, or the lines 280 or of electronic components of the control unit 260.

According to the approach presented here, thus the above-mentioned causes or errors occurring during operation of the steam cooking appliance can be detected and identified by a simple, additionally integrated monitoring of the flow of current through the heating element - combined with a time query. The user can then be notified, for example via a plain text display in a display or via an acoustic signal, the detected cause or a detected error image. Other sensors such as a level sensor for the level of the water tank 210 can be avoided in this way cost-saving.

Fig. 4 FIG. 12 shows a flowchart of one embodiment of a method 400 for determining different malfunction causes of a steam cooker having a heating element for heating water in an evaporator bowl. The method 400 includes a first step of detecting 410 a period of time from activating a current flow through the heating element to interrupting the flow of current through the heating element. Furthermore, the method comprises a second step of determining 420 a first malfunction cause if the detected time duration has a value that lies within a first time interval. Additionally or alternatively, in the step of determining a second malfunction cause may be determined when the detected time duration has a value that is in a different from the first time interval second time interval. Furthermore, the method 400 comprises a step of checking a possible calcification of the evaporator shell, in which the calcification of the evaporator shell is detected when a maximum permissible current flows through the heating element during a test period and the current flow through the heating element is interrupted within this test period.

REFERENCE NUMBERS

100

household appliance

110

hob

115

cooking zone

120

oven

125

oven door

130

door handle

135

window

140

Ausblasspalt

145

front panel

150

Control panel

155

controls

200

Steam cooker

205

oven

210

water tank

220

Pump or solenoid valve

230

heating element

240

Protector or circuit breaker

250

evaporator dish

260

Control or error detection device

270

Temperature sensor, PT1000 sensor

275

warning device

280

first electrical line

285

second electrical line

287

Current flow through the heating element

288

Thermal bridge between the heating element and the evaporator shell

290

third electrical line

292

Filling or activation signal

295

pipeline

300

measured or recorded duration

U1

Malfunction cause "dry run"

U2

Malfunction cause "shell calcified"

T3

Test duration

U3

Malfunction cause "empty cooking"

U4

Malfunction "Heating element malfunction, circuit breaker, ..."

Z1

first time interval

Z2

second time interval

Z3

third time interval

400

Method for determining a malfunction cause of a steam cooking appliance

410

Step of grasping

420

Step of determining

430

Step of checking

Claims (13)

A method (400) for determining different malfunction causes (U1, U2) of a steam cooker (200) having a heating element (230) for heating water in an evaporator dish (250), characterized in that the method (300) comprises the following steps : Detecting (410) a period of time (400) from activating a current flow (287) through the heating element (230) until interrupting the flow of current (287) through the heating element (230); and - determining (420) a first malfunction cause (U1) when the detected time period (300) has a value which is in a first time interval (Z1) and / or
Determining a second malfunction cause (U2) when the detected time period (300) has a value which is in a second time interval (Z2) different from the first time interval (Z1). A method (400) according to claim 1, characterized in that in the step of determining (420) the first malfunction cause (U1) represents a dry running of the steam cooking appliance (200). Method (400) according to claim 1 or 2, characterized in that in the step of determining (420) as the first time interval (Z1) a time interval is used which comprises values that lie in an interval of 1 second to 20 seconds. Method (400) according to one of the preceding claims, characterized in that in the step of determining (420) the second malfunction cause (U2) represents a calcification of the evaporator shell (250). Method (400) according to claim 4, characterized in that in the step of determining (420) as a second time interval (Z2) a time interval is used which comprises values which are greater than the values of the first time interval (Z1), especially values that are in an interval of more than 20 seconds to 60 seconds. Method (400) according to one of the preceding claims, characterized in that the method (400) further comprises a step (430) of verifying a possible calcification of the evaporator shell (250), in which the calcification of the evaporator shell (250) is then recognized, if during a test period (T3) a maximum permissible current flows through the heating element (230) and within this test period (T3) the current flow (287) is interrupted by the heating element (230). Method (400) according to one of the preceding claims, characterized in that, in the step of determining (420), a third malfunction cause (U4) is further determined if the detected time period (300) has a value which is smaller than the values of the first one Time interval (Z1). Method (400) according to claim 7, characterized in that in the step of determining (420) the third malfunction cause (U4) indicates a defect of a power supply to the heating element (230), a defect of the heating element (230), a defect of a circuit breaker (240 ) of the heating element (230) or a defect of a thermal bridge (288) between the heating element (230) and the evaporator shell (250). Method (400) according to one of the preceding claims, characterized in that, in the step of determining (420), a further malfunction cause (U3) is determined if the current flow (287) was interrupted by the heating element (230), subsequently an activation signal (292 ) was discharged to a pump (220) connected between the evaporator shell (250) and a water tank (210), then the current flow (287) was turned on again by the heating element (230) and the current flow (287) then after a re-detected time period (300) having a value which is in the first time interval (Z1). Method (400) according to one of the preceding claims, characterized in that in the step of detecting (410) the time period is determined which is determined by interrupting the flow of current due to opening of a circuit breaker (240) connected in series with the heating element (230) is. Method (300) according to one of the preceding claims, characterized in that, in the step of determining (420), the first (U1) or second malfunction cause (U2) is transmitted to a warning device (275) of the steam cooking appliance (200), which one of the determined Malfunction cause (U1, U2) corresponding signal acoustically and / or optically outputs. A steam cooker (200) having an evaporator bowl (250) with a heating element (230) configured to heat water in the evaporator bowl (250) and at least one circuit breaker configured to allow current to flow through the heating element (230) characterized in that the steamer (200) has the following feature: an error monitor (260) configured to detect a period of time (300) between turning on a current flow (287) through the heating element (230) and interrupting current flow (287) through the heating element and detecting a first malfunction cause (U1) of the steam cooker (200) if the detected time duration (300) has a value that lies within a first time interval (Z1) and / or a second malfunction cause (U2) of the steam cooker (200) if the detected time period ( 300) has a value which is in a second time interval (Z2) different from the first time interval (Z1). Oven (120), characterized in that the oven (120) has a Dampfgargerät (200) according to claim 12.

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