EP1565689B1 - Method for operating a cooking hob, and cooking hob - Google Patents

Abstract

A gas cooking hob and a method of operating the hob including at least two physical cooking points and at least one electronic control component. A second one of the two cooking points located at a greater distance from the electronic control component than the first cooking point. The first cooking point is rendered inoperational or its calorific output is reduced when a first threshold temperature of the electronic control component is exceeded. The second cooking point is remains operational or its calorific output remains unchanged.

Description

The present invention relates to a hob, in particular a gas hob, and a method for operating the hob with at least two cooking zones and with at least one electronic control component, of which hotplates at least a second cooking point is further spaced from the electronic component as a first cooking point.

A method is known for operating a hob, in which the gas burners are switched off to protect against overheating of electronic components of the gas hob when the temperature of the electronic component exceeds a temperature limit. The temperature limit corresponds to the maximum permissible temperature, exceeding which there is a risk of overheating of the electronic components.

Corresponding methods show the documents US-A-4 554 438 and EP-A-0 586 104 ,

The object of the present invention is to provide a hob, in particular gas hob, and a method for operating a hob, in order to improve its usability.

The object of the invention is achieved by a method having the features of claim 1. According to the characterizing part of claim 1, the electronic component closest to the first cooking point is assigned a temperature limit independent of the second cooking point in the process. If the temperature of the electronic component exceeds this temperature limit, only the nearest first hotplate to prevent overheating of the electronic component is put out of service or reduced its heating power output. By contrast, the second hotplate remains usable for an operator.

According to the invention, it is particularly advantageous in the case of gas cooking fields if the second cooking point, ie the second gas burner, remains in operation. Namely, in this case, a primary air flow to the second gas burner promotes effective cooling of the electronic component. The primary air flow results when Convection air from the environment is sucked into the leading to the gas burner gas supply line.

The following, directed to gas hobs embodiments apply analogously also generally for electric cooktops with corresponding cooking zones: According to a particular embodiment, the temperature limit may be on the order of about 20 K below a maximum allowable temperature. This must not be exceeded if the thermal load of the electronic component is high. The first hotplate is therefore turned off before reaching the maximum temperature or reduced in its heating power. In this way, it is achieved that despite an operation of the remotely located cooking point, the component temperature does not rise to the maximum temperature.

To increase the serviceability of the gas hob, it is advantageous if the operability or the heating power output of the first hob still restored or reset during the hob operation. In other words, while additional gas burners are in operation, the provision of the first gas burner takes place. In circuit technology particularly simple manner, therefore, the electronic control device of the gas hob can be assigned a timer. The timer prevents until the expiration of a predetermined cooling time interval, the provision of the first gas burner.

The length of the cooling time interval can be predetermined as follows: First, a time course of the component temperature immediately after entering the cooling time interval is detected. Based on the detected time history, the length of the time interval is predetermined.

Alternatively and / or additionally, the pitch angle of the time characteristic of the component temperature can be permanently monitored: If the component temperature falls in a pitch angle that is greater than a predetermined pitch angle stored in the control unit, the provision of the first gas burner takes place.

In terms of safety, it is particularly advantageous if the resetting of the first gas burner takes place as soon as the component temperature falls below the temperature limit again. In particular, the first gas burner can be reset when the component temperature falls below a lower temperature limit below the temperature limit. This is advantageous in a nearly continuous measurement of the component temperature. In a continuous measurement, namely, the measured temperature values within a tolerance band can fluctuate around an average component temperature. The lower temperature limit lies around this tolerance band below the actual temperature limit. A constant switching on / off of the gas burner is thus prevented when the component temperature is in the range of the temperature limit.

It is particularly easy to use if the heat output of the first gas burner before exceeding the temperature limit of the heating output after falling below the temperature limit. This is easy to accomplish in particular in so-called fully electronic gas hobs. In the case of fully electronic gas hobs, the power level of a hotplate can be stored by control electronics. When the first gas burner is switched on again, the stored power level of the first gas burner automatically resets itself by means of the control electronics.

If, after a successful reduction of the heat output at the first hob, the component temperature curve does not decrease, further measures to protect against overheating of the electronic component can be taken: It is advantageous, first the first cooking is switched off completely.

If the component temperature curve does not drop even after the first gas burner has been switched off, the second gas burner can also be switched inoperative or reduced in its heating power output. This measure can be realized in circuit technology simple manner, if the component temperature is still above the temperature limit after a certain period of time.

Analogous to the first gas burner, the second gas burner can also be assigned its own second temperature limit. This is above the first temperature limit. If the component temperature exceeds the second temperature limit, the second gas burner is additionally deactivated or its heating output is reduced. This variant is preferred for safety reasons, since the second gas burner is only actuated when the associated temperature limit is actually exceeded.

The serviceability of the gas cooker field can be further increased if each of the gas burners of the gas hob is assigned its own temperature limit. The values of the associated temperature limits increase as the distance between the gas burners and the electronic component increases. If the component temperature exceeds one of the temperature limits, the associated gas burner is put out of operation or its Heizleistungsabgabe reduced. When the component temperature rises, therefore, after the first temperature limit has been exceeded, first the first gas burner is switched off or its heating power is reduced. Subsequently, if appropriate, the more distant gas burners are switched off in turn or their heating powers are reduced. The temperature limit of the most remote to the electronic component gas burner can be designed in the range of the maximum allowable temperature for the electronic component.

• Figur 1 ein Gaskochfeld in einer Ansicht von oben;
• Figur 2 eine Seitenschnittansicht entlang der Linie I-I aus der Figur 1;
• Figur 3 ein Blockdiagramm des Gaskochfelds gemäß dem ersten Ausführungsbeispiel;
• Figur 4 ein in einer elektronischen Steuereinrichtung des Gaskochfeldes gespeichertes Diagramm;
• Figur 5 ein Temperatur und Betriebsfähigkeitsdiagramm gemäß dem ersten Ausführungsbeispiel;
• Figur 6 ein Blockdiagramm entsprechend der Figur 3 gemäß dem zweiten Ausführungsbeispiel;
• Figur 7 ein Temperatur und Heizleistungsdiagramm gemäß dem zweiten Ausführungsbeispiel;
• Figur 8 ein Temperatur- und Heizleistungsdiagramm , gemäß dem dritten Ausführungsbeispiel; und
• Figur 9 ein Temperaturdiagramm gemäß dem vierten Ausführungsbeispiel.

Below, four embodiments of the invention are described with reference to the accompanying figures. Show it:

• FIG. 1 a gas hob in a view from above;
• FIG. 2 a side sectional view along the line II of the FIG. 1 ;
• FIG. 3 a block diagram of the gas hob according to the first embodiment;
• FIG. 4 a diagram stored in an electronic control device of the gas hob;
• FIG. 5 a temperature and operability diagram according to the first embodiment;
• FIG. 6 a block diagram according to the FIG. 3 according to the second embodiment;
• FIG. 7 a temperature and Heizleistungsdiagramm according to the second embodiment;
• FIG. 8 a temperature and Heizleistungsdiagramm, according to the third embodiment; and
• FIG. 9 a temperature diagram according to the fourth embodiment.

In the FIG. 1 is shown in a cutout of a worktop used gas hob. The gas hob has four gas burners 1, 2, 3, 4. The gas burners can be actuated by provided in a front panel 6 control knob 7. As it is in the FIG. 2 is indicated, carrier grids 8 are arranged above the gas burner, on which Gargutbehältnisse not shown off. According to the FIG. 2 the gas hob on a bottom tray 9 with raised side walls 10. On the side walls 10 of the bottom tray 9, a cover plate 11 is attached. The cover plate 11 is seated with its outer periphery on the worktop 1. By in the cover plate 11 provided mounting openings protrude the gas burner 1, 2, 3, 4. The bottom tray 9 defines together with the cover plate 11 a trough interior 12. In this are electronic components such arranged about an ignition device 13 or a control device 14 for the gas burner.

In the rear side wall 10 of the bottom pan 9 primary air openings 15 are formed. Through this flows a convection air in the trough interior 12. The convection air is the primary air supply for air intake 16 of gas nozzles 17 of the gas burner. A flow path of the convection air is in the FIG. 2 indicated by the arrows I. For cooling the electronic components 13, 14, these are arranged in the flow path I.

In the block diagram of FIG. 3 is an example of the functional connection between the components 13, 14 shown with the gas burner 1. The further gas burners 2 to 4 are in identical manner with the components 13, 14 in connection. Consequently, the gas burner 1 is supplied with gas via a gas supply line 21. In the gas supply line 21, an electromagnetic safety valve 22 is arranged, which is opened or closed by the electronic control device 14. The gas volume flow in the gas supply line 21 required for a desired burner heating power can be set by means of a gas tap 23. The gas cock 23 is to be operated with the control knob 13. The control knob 13 is also coupled to a signal generator 25, which is via lines 27 to the electronic control device 14 in a signal connection. For flame monitoring, the gas burner 1 is assigned a thermocouple 29, which detects the presence of a flame on the gas burner 1. The electronic control device 14 is in addition via a line 28 in signal communication with the ignition device 13. This controls an ignition electrode 18 to ignite a flame on the gas burner 1.

To start up the gas burner 1, a pressure and / or rotational movement is exerted on the control knob 13. As a result, 25 corresponding signals generated by the signal generator and passed through the lines 27 to the electronic control device 14. The electronic control device 14 detects the signals of the signal generator 25 and controls the ignition device 13 accordingly. Their ignition electrode 18 then ignites a flame on the gas burner 1. At the same time, the electronic control device 14 acts on the hitherto closed safety valve 22 with an external current. Due to the external current, the safety valve 22 and therefore the gas supply line 3 to the gas burner 1 is opened After gas ignition on the gas burner 1, the thermocouple 29 is heated by the flame of the gas burner 1. The thermal energy thus generated on the thermocouple 29 takes over the function of the external current and stops at the Set the safety valve 22 open. After a flame extinction on the gas burner 1, the thermocouple cools down, whereby no more thermal power is generated. As a result, the electronic control device 14 closes the safety valve 22 and the gas supply line 21 to the gas burner 1 is blocked.

According to the invention is in the FIG. 3 the electronic control device 14 is connected to a temperature sensor 33. The temperature sensor 33 detects a temperature T _K in the electronic components 13, 14. The sensed temperature T _K is compared with data stored in the control device 14 limits temperature T _1, T _2, T _3, T. ₄ Each of the temperature limits T ₁ , T ₂ , T ₃ , T ₄ is according to the diagram of FIG. 4 one of the four gas burners 1, 2, 3, 4 assigned. From the diagram of FIG. 4 shows that the values of the stored temperature limits T ₁ , T ₂ , T ₃ , T _{4 increase} with increasing distance of the gas burner to the electronic components 13, 14. Consequently, the gas burner 1 closest to the electronic components 13, 14 is assigned a lower temperature limit T ₁ of 90 ° C. The most widely spaced from the electronic components 13, 14 of gas burner 4 is associated with an upper temperature limit T ₄ of 110 ° C. The upper temperature limit T ₄ is approximately in a range that is reached at a maximum allowable heat load of the components 13, 14.

A time characteristic of the temperature T _K measured by the temperature sensor 33 of the electronic components 13, 14 is shown in the temperature diagram of FIG FIG. 5 As a result, at the beginning of the burner operation after the time t _0, the component temperature T _K initially rises steadily until the first temperature limit T _{1 is} exceeded. This is assigned to the first gas burner 1. In this case, the safety valve 22 in the gas supply line 21 to the first gas burner 1 is controlled and closed by the electronic control device 14. The first gas burner 1 is thus set from the time t ₁ out of service, as from the operability diagram of FIG. 5 , below. By switching off the first gas burner 1, the component temperature T _K increases less rapidly after time t ₁ until the second temperature limit T _{2 has been} exceeded by time t ₂ . This is associated with the second gas burner 2. Accordingly, the electronic control device 14 at time t ₂ closes the safety valve 22 of the second gas burner 2. As a result, the component temperature T _K after the time t ₂ below the temperature limits T ₃ , T _{4 of} the two remaining gas burner 3, 4. The gas burner 3, 4 therefore remain operational. At the time t ₃ , the component temperature T _K drops below the second temperature limit T _{2 again.} The electronic control device 14 therefore releases the safety valve 22 of the second gas burner 2 again at the time t ₃ . The second gas burner 2 can therefore at a corresponding operation of the associated control knob 13 are put into operation again. At the time t ₄ , the component temperature T _K also falls below the first temperature limit T ₁ . The electronic control device 14 therefore releases the safety valve 22 of the first gas burner 1 again from the time t ₄ .

In the second embodiment of FIGS. 6 and 7 Power adjustment of the gas burners 1, 2, 3, 4 is not via gas taps 23, but via gas control valve assemblies 35. The gas control valve assemblies 35 are connected between the electronic control device 14 and each of the four gas burners 1, 2, 3, 4. For illustration is in the FIG. 7 only the gas control valve arrangement 35 connected between the gas burner 1 and the control device 14 is shown. This is arranged in the gas supply line 21 and has four parallel partial gas lines through which flows a partial gas flow in each case. In each of the partial gas lines, an electromagnetic control valve 37 is arranged with a downstream throttle 39. Their throttle diameters can differ from each other. Downstream of the throttles 39, the partial gas lines are brought together again in the gas supply line 21. In response to the power level set by the operator, the controller 14 opens one or more of the control valves 37 in the parallel partial gas lines. The size of the gas flow from the gas control valve arrangement 35 to the gas burner 1 therefore depends on the number of opened control valves 37.

In the FIG. 7 is a gas hob operation according to the second embodiment illustrated by a temperature and Heizleistungsdiagramms. According to the lower heating power diagram, all four gas burners 1, 2, 3, 4 are in operation at different heating powers P ₁ , P ₂ , P ₃ , P ₄ at time t ₀ . The component temperature T _K increases steadily after the time t ₀ . At the time t ₁ , the component temperature T _K exceeds the first temperature limit T ₁ . The four control valves 37 of the first gas burner 1 are therefore closed from the time t ₁ . 14 simultaneously stores the control means controls the positions of the control valves 37 of the gas burner 1 at time t. ₁ At the time t ₂ , the component temperature T _K exceeds the second temperature limit T ₂ . The electronic control device 14 accordingly closes all the control valves 37 of the second gas burner 2 and at the same time stores their positions. At time t ₃ , the component temperature T _K again falls below the second temperature limit T ₂ . The electronic control device 14 therefore controls the control valves 37 of the second gas burner 2 according to their stored positions. The second gas burner 2 is therefore operated from the time t ₃ again with its heating power P ₂ . In the same way, the first gas burner 1 is put into operation again at the time t ₄ .

In the FIG. 8 a temperature and Heizleistungsdiagramm according to the third embodiment is shown. The structure of the gas hob of the third embodiment is similar to the gas hob of the second embodiment. As in the heat output diagram of the FIG. 8 is shown immediately after exceeding one of the temperature limits T ₁ , T ₂ , T ₃ , T _4, a cooling time interval t _a , t _b predetermined for the off gas burner. For predetermining the length of the cooling-time interval t _a , the curve of the component temperature T _{K is first} detected in a time span a. The period of time a begins immediately after the component temperature T _K has exceeded the temperature limit T ₁ . The electronic control device 14 determines the length of the cooling time interval t _a for the first gas burner 1 on the basis of the curve profile of the component temperature T _K recorded in the period a. After the cooling time interval t _a has elapsed, the first gas burner 1 is stored again with it Heating power P ₁ operated. In the same way, the length of the time interval t _b for the second gas burner 2 is determined after the component temperature T _K has exceeded the second temperature limit T ₂

Alternatively or additionally, the gas burners switched inoperative can also be switched back to operation when the component temperature T _K falls within a pitch angle α which is greater than a predetermined pitch angle. The predetermined pitch angle is stored in the controller 14. Thus, according to the temperature diagram of FIG. 9 detected at time t _1, the pitch angle α,

The detected pitch angle α is greater than the stored pitch angle. As a result, the controller 14 turns forward haste ready for use again the first gas burner 1, before the component temperature T _K is again fallen below the temperature limit T uncritical. ₁

Claims (15)

1. Method of operating a cooking hob, particularly a gas cooking hob, with at least two cooking positions (1, 2, 3, 4) and with at least one electronic control component (13, 14), of which cooking positions at least one second cooking position (2, 3, 4) is spaced further from the electronic component (13, 14) than a first cooking position (1), characterised in that the first cooking position (1) is taken out of operation or the heating power output (P₁) thereof is reduced if a temperature (T_K) of the electronic component (13, 14) exceeds a temperature limit (T₁), whilst the second cooking position (2, 3, 4) remains operationally ready or the heating power output (P₂, P₃, P₄) thereof remains unchanged.
2. Method according to claim 1, characterised in that the temperature limit (T₁) lies below, particularly in an order of magnitude of approximately 20 K, a temperature range reached in the case of maximum permissible thermal loading of the electronic component (13, 14).
3. Method according to one of the preceding claims, characterised in that the operational capability or the heating power output (P₁) of the first cooking position (1) is restored again even during cooking hob operation.
4. Method according to claim 3, characterised in that the restoration of the first cooking position (1) is carried out when a predetermined cooling-down time interval (t_a) has elapsed.
5. Method according to claim 4, characterised in that the length of the cooling-down time period (t_a) is predetermined on the basis of the time plot of the component temperature (T_K) directly after entry into the cooling-down time period (t_a).
6. Method according to any one of claims 3 to 5, characterised in that the restoration of the first cooking position (1) is carried out when the time plot of the component temperature (T_K) drops into a gradient angle (α) greater than a predetermined gradient angle.
7. Method according to any one of claims 3 to 6, characterised in that the restoration of the first cooking position (1) is carried out when the component temperature (T_K) falls below the temperature limit (T₁), preferably a temperature lower limit lying thereunder.
8. Method according to any one of the preceding claims, characterised in that the heating power output (P₁) of the first cooking position (1) after reinstatement corresponds with the heating power output (P₁) prior to the temperature limit (T₁) being exceeded.
9. Method according to any one of the preceding claims, characterised in that after reduction of the heating power output (P₁) has been carried out the first cooking position (1) is switched off if the component temperature (T_K) has not fallen below the temperature limit (T₁).
10. Method according to any one of the preceding claims, characterised in that in addition to the first cooking position (1) the second cooking position (2) is switched off or the heating power output (P₂) thereof is reduced if the component temperature (T_K) has not fallen below the temperature limit (T₁) after a specific time period.
11. Method according to any one of the preceding claims, characterised in that the second cooking position (2) is switched off or the heating power output (P₂) thereof is reduced if the component temperature (T_K) exceeds a second temperature limit (T₂) lying above the first temperature limit (T₁).
12. Method according to any one of the preceding claims, characterised in that a number of temperature limits (T₁, T₂, T₃, T₄) is stored and that at least one of the cooking positions (1, 2, 3, 4) is switched to be operationally incapable or the heating power output (P₁, P₂, P₃, P₄) thereof is reduced if the component temperature (T_K) exceeds one of the temperature limits (T₁, T₂, T₃, T₄).
13. Method according to claim 12, characterised in that a respective temperature limit (T₁, T₂, T₃, T₄) is associated with each of the cooking positions (1, 2, 3, 4) of the cooking hob and the values of the temperature limits of the cooking positions rise with increasing spacing of the cooking positions from the electronic component (13, 14).
14. Method according to any one of the preceding claims, characterised in that in the case of a gas cooking hob a cooling-down of the electronic component (13, 14) is assisted by a primary air flow (I) to the second cooking position (2, 3, 4) disposed in operation.
15. Cooking hob, particularly gas cooking hob, with a control device (14), at least two cooking positions (1, 2, 3, 4) and at least one electronic component (13, 14), of which cooking positions at least one second cooking positions (2, 3, 4) is spaced further from the electronic component (13, 14) than a first cooking position (1), characterised in that the first cooking position (1) is taken out of operation or the heating power output (P₁) thereof is reduced by means of the control device (14) if a temperature (T_K) of the electronic component (13, 14) exceeds a temperature limit (T₁), whilst the second cooking position (2, 3, 4) remains operationally ready or the heating power output (P₂, P₃, P₄) thereof remains unchanged.

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