EP0818655A2 - Method and device for controlling the size of the flame of a gas cooking apparatus - Google Patents

Abstract

A device and a method for the controlled reduction of the gas flow Q fed to a burner nozzle (3) of a gas-operated cooking or baking device via a gas feed line (1) are to be improved in order to adjust the gas flow in steps that are reproducible with high accuracy by branching the gas feed line (1) into a number n of partial gas lines (10, 20, 30, 40) connected in parallel, by means of which a partial gas flow Q _k with k = 1,2,3, ..., n can be fed to the burner nozzle (3), and each have a control element, the control elements are each connected to the gas feed line (1) on their gas inlet side and to the burner nozzle (3) on their gas outlet side, and each have a switching element (11, 21, 31, 41) for switching the on and off they flow through partial gas flow Q _k and a throttle element (12, 22, 32, 42) for throttling the partial gas flow Q _k flowing through them and the switching elements (11, 21, 31, 41) optionally, each n can be switched on and off according to the selected heating output. Alternatively, a number n of throttle elements connected in series, each with switching elements connected in parallel, is proposed.

Description

The invention relates to a device and a corresponding Method of controlled gradual reduction of a burner nozzle of a gas-operated cooking or Baking device supplied via a gas supply gas flow Q.

Common cooking or baking devices, for example gas stoves, Gas hobs, gas hobs or gas ovens, have one or more burners in which the gas is mixed with atmospheric oxygen and burned. The gas supply to the burner is via a gas supply line from a gas pipeline network, a gas tank or a gas bottle is supplied with gas. With a city gas pipeline network the feed pressure is approx. 8 mbar; he however, is subject to fluctuations and can reach 4 mbar sink. For cooking and baking equipment operated with camping gas the feed pressure is approx. 50 mbar.

The burners have a burner nozzle that is connected the burner to the gas supply line the relevant, the flow resistance limiting the outflowing gas flow forms and thus the maximum heating power of the Brenners determined. The flow resistance in the gas supply line can usually be neglected will. The maximum heating output of the burner must, however in practical use by the user at the moment required heating power can be reduced. The reducing the heating power must therefore be with the help of a suitable one Control anytime, easily and on a value as close as possible to the desired or required Heat output can be carried out.

To reduce the heating output of the burner, the following state of the art conventional continuous Control valves used. By partially closing the Valve is throttled the gas flow and the desired Gas flow rate and thus the desired heating output set. In most cases, this is done Manual adjustment of the valves. The setting accuracy the valve is relatively small. Furthermore show such proportional valves also a hysteresis in the control behavior, so the flow rate doesn't just depend on the position of the valve or the display on the associated setting button depends, but also in which direction the valve for setting the desired flow rate is actuated (i.e. opened or closed) and how long the previous adjustment path is.

For this reason, the operator orientates himself in everything Usually not on the scale assigned to the valve, but changes the position of the valve until the desired one Heat output, which is based on the size of the flame or the cooking or baking behavior of the dishes can, is achieved. By including this Scale differences compensating operator in the Control of the heating power can be accepted that the setting accuracy and reproducibility of the gas flow are very small and therefore the flame size and the heating output with the same setting of the controller or the scale can be significantly different.

In applications where an automatic or motorized Setting the gas flow is desired it is known to adjust the valves stepper motors too use that are controlled by a control circuit. However, this solution is technically very complex and expensive. The problem also arises here that the proportional or available Valves show hysteresis behavior so that when activated a certain valve position by means of Stepper motor depending on the control direction and control path length Differing gas flows result. So be in these cases also in the respective settings no heat outputs assigned in a reproducible manner achieved.

From document DE 4225789 A1 is a measuring and testing device for one-off setting and adjustment of a Gas heater known in the two in a row switched gas pressure regulator, a programmable logic controller Control with the necessary for the respective adjustment cases Working characteristics and four pressure gauges provided are. There are also a number of parallel branches provided, each from a series connection a solenoid valve and a reference nozzle. To adjust the gas flow for the adjustment of the Gas heater is only one of the branches open; only in exceptional cases is by optional Switching several nozzles in parallel has a certain gas flow achieved. This known device is technical very complex, so that they are in the context of production control to adjust an adjustable throttle or an adjustable gas device pressure regulator of a gas heater suitable, but not for permanent adjustment the heating power of a gas-powered cooking or Baking device by the user.

From the patent US-4,585,161 is a forced draft burner known in which two continuously adjustable Control valves and a balance controller the amount and that Ratio of gas and combustion air can be controlled. To the adjustable control valve in the gas supply another, controllable auxiliary valve connected in parallel. The degrees of opening are controlled by means of a control device of the gas valve and the auxiliary valve to achieve a constant gas flow regulated. There are sensors for this required to measure gas flow rates.

From document CH-303445 is an adjustable gas burner known a gas stove, in which by means of several side-by-side, switchable nozzles one and the same Mixing tube of the gas burner is fed. The single ones Nozzles are turned on and off by a common tap switched off, the intermediate stages by throttling by means of one upstream of the individual nozzles Cross-sectional narrowing can be realized.

A gas regulator is known from document FR-911.892, which is a series of openings with different diameters has, of which at a desired heating level exactly one for the gas flow is opened.

The present invention takes this state into account the technology based the task, a device and a method for controlled reduction of a burner nozzle a gas-powered cooking or baking device to create a gas feed line Q, by means of which the gas flow through the user of the device adjustable in steps reproducible with high accuracy is. In other aspects, it is desirable that the method and the device are technically inexpensive are feasible, easy to use and durable work reliably.

The invention is based on the consideration, a number provide throttle elements by means of which a through the burner nozzle and the connection pressure given, maximum Gas flow can be reproduced in stages in a defined manner can be reduced. To switch the The function of the respective throttle elements are switching elements provide the gas flow through each Can turn throttle element on and off. Through the Combination of certain switching elements switched on and off can then achieve a defined reduction in the gas flow be performed or if all throttling elements are open, the maximum gas flow is achieved will.

The idea of the invention can be done in two ways practically implement, namely by a parallel connection or by connecting throttle elements in series.

To achieve the above-mentioned object in a method and a device of the type described at the outset, it is proposed according to a first aspect of the invention that the gas supply line is branched into a number n of partial gas lines connected in parallel, by means of which a partial gas flow Q _k with k = 1 is given to the burner nozzle , 2,3, ..., n can be supplied, the partial gas lines each having a control element which is connected on its gas inlet side to the gas supply line and on the gas outlet side to the burner nozzle. The control members each comprise a switching element for switching the partial gas flow Q _k flowing through and off and a throttle element for throttling the partial gas flow Q _k flowing through them, the switching elements optionally being switchable on and off depending on the heating power selected.

By splitting the gas stream into several partial gas flows that can be switched on and off individually it is possible to give the burner nozzle the gas flow in stages, the more open to the respective combinations and correspond to closed switching elements. A partial gas stream is the gas stream that the Burner nozzle supplied through the respective partial gas line when their switching element is open. The whole the gas flow supplied to the burner nozzle results from the Sum of the partial gas flows. In this way it is possible Realize gradations in the gas flow by Switching switching elements and partial gas flows on and off can be set reproducibly.

According to another aspect of the invention, one Method and an apparatus of the aforementioned Art suggested that the gas flow Q a number n in Series of control elements connected to the gas supply line passes through, each a throttle element for throttling of the gas stream flowing through it and one of the throttle element parallel switching element for switching on and off Having a bypass switched off to the throttle element, and the switching elements optionally, depending on the desired Heating power, can be switched on and off. Of course, mixed forms are also possible in which throttle elements connected in parallel as well as in series are.

The control bodies can in principle the function of Switching element and that of the throttle element in one Realize assembly, for example in the form of an electromagnetic actuated binary throttle valve, the has a closed and a throttle position. In this In this case, the control members each comprise a switching element and a throttle element in the sense that they are these elements Realize in a single control at the same time.

In general, however, it will be more advantageous to Switching elements and the throttle elements in separate components to realize a high reproducibility of the set gas flow or an inexpensive embodiment to realize. By separating the tax bodies into a switching element and a separate throttling element it is possible, depending on suitability, costs, Accuracy, security, etc. for the respective function to use particularly suitable components.

The switching elements are individually by hand, using a respective control device or advantageously by means of a common control device on and off. In the most general case there is a number n of control devices provide with which each switching element can be switched on and off individually. For simplification operation, however, it is particularly advantageous one for the switching elements of a burner nozzle, provide common control device, each has different switching levels to which the the combination of the gradations corresponding to the partial gas flows are assigned to the gas flow. By setting the control device, for example the associated one Controller or by pressing the corresponding step key, a certain switching level is selected, and the Control unit combines the corresponding switching elements and partial gas streams to generate the preselected one Burner nozzle to be supplied gas stream.

In order to implement a large number of gradations of the gas flow in the case of throttle elements connected in parallel according to the invention, it is advantageous if the flow resistances of the n control elements, in particular the throttle elements, are dimensioned such that at least two partial gas flows Q _k are different from one another. The maximum number of possible gradations can advantageously be achieved in that all flow resistances or partial gas flows Q _{k are} different, since in this case the largest number of differing sums of partial gas flows can be formed. This maximum number of gradations is 2 ⁿ . When all switching elements are closed, the gas flow is switched off. When all switching elements are open, the maximum gas flow Q _{max flows} . The (2 ⁿ -2) further gradations lie between these two end values. As a rule, in the majority of the gradations, ie at least 0.5 · 2 ⁿ = 2 ^n-1 , at least more than 0.25 · 2 ⁿ = 2 ^n-2 gradations, more than one partial gas flow Q _{k will be} open. Due to the throttle elements, the value of Q _{max may} be somewhat lower than the theoretical maximum value caused solely by the burner nozzle. If necessary, this deviation can be compensated for by a different, adapted or differently set burner nozzle.

For the practical application of the invention it is proposed according to a particularly advantageous feature that the flow resistances of the n control elements are dimensioned such that the n partial gas flows Q _k with k = 1,2,3, ..., n are essentially a consequence of the Values Q k = Q Max · 2 k-1 / (2nd n -1) form. Q _max denotes the maximum gas flow Q which is produced when all n switching elements are opened and is fed to the burner nozzle. In this way, by accumulating partial gas flows m = 1, 2, 3,..., 2 ⁿ different gas flows Q _{m can be} set essentially the values Q m = Q Max · (M-1) / (2nd n -1) accept. In this case, the entire control range of the gas flow is evenly graduated from 0 to Q _max , with the distance from stage to stage Q m + 1 - Q m = Q Max / (2nd n -1) is. In other words, the gradations of the set gas flow are evenly between 0 and the maximum value, which makes it possible to set the heating output clearly and easily, especially when the gas control is operated manually.

The number n of partial gas lines is at least two. A maximum of 2 ² = 4 gradations of the gas flow can be achieved with two partial gas lines. Since one level is the exhibition and one level is the maximum position, only two possible intermediate values remain. This may be sufficient for gas grills, for example, but will generally not meet the requirements for a sufficiently fine metering of the heating power in gas-operated cooking appliances.

According to a first preferred feature is therefore proposed that the number n of partial gas lines n = 3 is such that a total of 2 ³ = 8 levels with the partial gas streams, which preferably substantially the values Q _max • 1/7, Q _max · 2 / 7 and Q _max · 4/7 can be set. The relative gradations related to Q _max which can be set by means of these partial gas flows then assume the values 0, 1/7, 2/7, 3/7, 4/7, 5/7, 6/7 and 7/7.

According to a second preferred feature, it is proposed that the number n of partial gas lines is n = 4. In this case have substantially preferably the partial gas streams, the values Q _max * 1/15 Q _max · 2/15, Q _max × 4/15 and Q _max · 8/15. The 2 ⁴ = 16 gradations that can be set have the values 0, 1/15, 2/15, 3/15, 4/15, ..., 14/15, 15/15.

With n = 3 or n = 4 partial gas lines, one can fine dosing of the gas flow and control of the heating power respectively. The gradation can be increased by increasing the number of the partial gas lines are refined, whereby in practical use cases usually with it achievable finer adjustment possibility not in one reasonable relation to the technical effort becomes. Especially for burners with a very high maximum Heating output can be a very fine gradation desirable be concerned with the invention throughout Area can be achieved easily and reproducibly.

It is obvious that, due to manufacturing tolerances and technical inaccuracies of the components, the partial gas flows Q _k often do not exactly assume the levels specified according to the formulas mentioned above, but can deviate from them within certain tolerance ranges. In practical applications it will generally be acceptable if the maximum deviation of the partial gas flows Q _k from the exact gradation is less than ± 20%, preferably less than ± 15%, preferably less than ± 10% and particularly preferably less than ± 5% .

In order for both series and parallel connection of Throttle elements one for practical use if possible manageable, simple and safe operating option To create, it is proposed that the Control device for the n switching elements an integer Number i has discrete switching positions, which each have a combination of the open and closed positions which is assigned to n switching elements. The Control device can, for example, a rotary or Step switch, a control panel with buttons that the respective Switch positions are assigned, or preferred also a "touch control panel", one by mere touch be operated switch. The user needs to be in in this case not about the individual control of the individual Switching elements to take care of since the control device the selected switching level automatically in the specified one Open and appropriate combination implements closed switching elements.

It can be advantageous if the number i of the switching positions the control device is smaller than the number the various realizable with the switching elements Gradations of the gas flow, for example, if not all levels for practical use are necessary. For example, it may be desirable be a fine gradation in the area of advanced cooking, in the other areas, however, a coarser gradation to provide the total number of adjustable levels in to keep practically reasonable limits.

For simple, manageable operation, it is advantageous if the combinations of the open and closed positions of the n switching elements are assigned a sequence of n = 1, 2, 3,..., I consecutive switching positions S _{m of} the control device such that the an ascending or descending sequence is formed in the respective switching position S _m from the sum of the partial gas flows Q _k , gas flows Q _m fed to the burner nozzle. In this case, the closest higher or lower heating level is set by increasing or decreasing the switch position, i.e. a monotonous adjustment option is achieved.

According to a preferred feature, it is proposed that the number i of the switching positions of the control device is 2 ⁿ , the switching positions being assigned exactly one of the possible combinations of the open and closed positions of the n switching elements. In this case, the maximum possible number of gradations must be realized. It is particularly advantageous if the sequence of m = 1, 2, 3,..., 2 ⁿ successive switching positions S _{m of} the control device is assigned to the combinations of the open and closed positions of the n switching elements in such a way that the gas flows Q _m , which, when connected in parallel in the respective switching position S _{m, are} composed of the sum of the partial gas flows Q _k , form an ascending or descending sequence which essentially contains the values Q m = Q Max · (M-1) / (2nd n -1) assumes. In this case, uniform gradations of the heating power are realized by means of the control device for successive switching positions, as the user is familiar with electronically controllable electric cookers and electric hobs. With a series connection of throttle elements, it will also be expedient that the switchable gas flows Q _{m form} an ascending or descending sequence. However, the requirement mentioned above with regard to a uniform gradation of the adjustable heating outputs will generally be difficult to meet.

It also applies here that for technical reasons there is a certain tolerance-based deviation of the set gas flow from the desired value, which can however be accepted under practical conditions. Accordingly, it is proposed according to a further advantageous feature that the maximum deviation of the sums Q _{m of} the partial gas flows Q _k assigned to the switching positions S _m from the exact gradation is less than ± 20%, preferably less than ± 15%, preferably less than ± 10% and is particularly preferably less than ± 5%.

The switching elements can in principle in any way are operated, for example mechanically, pneumatically or hydraulic. According to a particularly preferred feature it is proposed that at least one switching element, preferably all switching elements can be actuated electrically.

The switching elements can be in an advantageous embodiment binary solenoid switching valves that are open and have a closed position. Such solenoid switching valves are known and fulfill those to be placed on them safety requirements. With such solenoid switching valves it is, as is generally the case with electrical actuatable switching elements, for an additional Feature advantageous if that occurs during the switching process Clacking is prevented or dampened. To this The electrical control signal can be used when opening and / or closing the switching element, at least in the area of the switching point, be edge-controlled, so that the switching process does not run abruptly. Advantageously is therefore an electrical circuit for gradual Increase and / or decrease the electrical Control current provided.

For a long service life and operational reliability of the invention It is advantageous that the device Carry out switching elements only a few switching cycles, namely only if the setting of the gas flow Q is changed becomes. They are therefore, if at all, only subject to a very long-term wear.

In more complex embodiments, the flow resistance the throttle elements in the factory or, if necessary be adjustable by the user. Come for this for example adjustable throttle valves in question that a calibration option for setting and adjusting of their choke resistance to a desired value. This can be an advantage if it is on the Achieving a high degree of accuracy of the gradations or of the set partial gas flows arrives, which then through exact setting and exact adjustment of the throttle elements is feasible. According to a preferred one, for the usual accuracy requirements to be set in practice sufficient feature is suggested that one, several or preferably all throttle elements one have a predetermined flow resistance. The Throttle elements can be used, for example, as capillaries, capillary tubes, Nozzle or pipe constriction can be realized. These embodiments are with satisfactory accuracy to implement inexpensively.

The advantages of a device and a method according to this invention exist over the prior art in that by means of known and commercially available components a desired, gradual reduction in gas flow rate a very high degree of reproducibility can be realized so that at the respective Setting the assigned control device reliably the same heating output is achieved. The control the device by controls can with a using inexpensive, commercially available components Control device take place. Another advantage is to see that the invention also exclusively with binary switching elements, i.e. without proportional valves is executable.

It should be noted that pressure fluctuations by the invention are not compensated in the gas supply line and consequently also affect the heating output. The In this respect, invention does not solve the problem in absolute terms reproducible gas flows and heating outputs realize, but solves the problem, a given maximum gas flow in a reproducible way to smaller ones Grading values. If the maximum gas flow is conditional due to fluctuations in the network pressure the reduced, graded gas flows accordingly to change. The reproducibility of the setting remains intact. In view of the fact that Network pressure fluctuations only affect the Affect heating output, only gradually and the changes in the heating output due to this accepted the conventionally used tap valves the invention represents a significant improvement compared to the prior art for reproducible, controlled reduction of the gas flow. If necessary the device according to the invention can also with a device that allows fluctuations in gas pressure the gas supply line compensated or reduced, combined will.

Let the following embodiments of the invention recognize other advantageous features and special features, the based on the schematic representations in the Drawings described and explained in more detail below will.

Fig. 1

Eine schematische Darstellung einer erfindungsgemäßen Vorrichtung mit vier Teilgasleitungen,

Fig. 2

eine Schaltmatrix einer Steuereinrichtung zu Fig. 1,

Fig. 3

eine Schaltmatrix einer Steuereinrichtung mit 10 Schaltstellungen,

Fig. 4

eine Schaltmatrix einer Steuereinrichtung mit 14 Schaltstellungen, und

Fig. 5

eine schematische Darstellung einer erfindungsgemäßen Vorrichtung mit drei in Reihe geschalteten Drosselelementen mit Bypass.

Show it:

Fig. 1

A schematic representation of a device according to the invention with four partial gas lines,

Fig. 2

2 shows a switching matrix of a control device for FIG. 1,

Fig. 3

a switching matrix of a control device with 10 switching positions,

Fig. 4

a switching matrix of a control device with 14 switching positions, and

Fig. 5

is a schematic representation of a device according to the invention with three throttle elements connected in series with bypass.

Fig. 1 shows one of a gas pipeline network, a gas tank or a gas bottle supplied gas supply line 1 for the supply of gas controlled according to the invention to a Burner nozzle 3, which is part of a burner 2, the e.g. built into a gas stove or gas oven can be. Those for gas-powered are not shown Cooking and baking devices usual security elements (Thermocouple and associated solenoid valve) that the When the flame goes out, interrupt the gas flow.

The gas feed line 1 branches into four partial gas lines 10, 20, 30, 40 connected in parallel, which then combine again to form a burner feed line 5 connected to the burner nozzle 3. The partial gas lines 10, 20, 30, 40 each have a control element for controlling the partial gas flows Q ₁ , Q ₂ , Q ₃ , Q ₄ . The control members each comprise a switching element 11, 21, 31, 41 and a throttle element 12, 22, 32, 42. In the preferred embodiment shown, all four switching elements are electrically actuated binary magnetic switching valves which have an open and a closed position, so that a Part gas flow Q _k can either be on or off. The independent opening and closing of the solenoid switching valves 11, 21, 31, 41 is controlled by a control device 4.

The throttle elements 12, 22, 32, 42 are capillaries which have a fixed flow resistance and are used to reduce the respective partial gas flow Q _k to a fraction of the maximum gas flow Q _max supplied. The capillary 12, for example, throttles the partial gas flow Q ₁ so that it is only 1/15 of the maximum gas flow when the solenoid switching valve 11 is open. Due to the lower flow resistance of the capillary 22, the partial gas flow Q _{2 is} reduced to 2/15 of the maximum gas flow when the solenoid switching valve 21 is open. The capillaries 32 and 42, on the other hand, only reduce the partial gas flows Q ₃ and Q ₄ when the solenoid switching valves 32 and 42 open to 4/15 and 8/15 of the maximum gas flow.

The capillaries 12, 22, 32, 42 are the respective solenoid switching valves 11, 21, 31, 41 in the flow direction downstream of the gas. On the one hand, this arrangement has safety-related advantages, as compared to a reverse arrangement in the closed position of a Solenoid switching valve 11, 21, 31 or 41 fewer components to be under gas pressure. On the other hand, it is advantageous that the time until the full partial gas flow is reached when opening a solenoid switching valve 11, 21, 31 or 41 passes, is smaller than with the reverse arrangement.

The gas flow Q _m fed to the burner nozzle 3 results from the sum of the switched-on partial gas flows Q ₁ to Q ₄ . For example, if only the solenoid switching valves 11 and 31 are open, the gas flow Q _m fed to the burner nozzle _{3 is} composed only of the partial gas flows Q ₁ and Q ₃ .

In the illustrated embodiment, the flow resistances of the capillaries 12, 22, 32, 42 are 1/15, 2/15, 4/15 and 8/15 according to the general formula Q k = Q Max · 2 k-1 / (2nd n -1) dimensioned such that 16 different gas flows Q _m can be supplied to the burner nozzle 3. This corresponds to the maximum number of gradations (2 ⁿ ) that can be achieved with four partial gas flows Q _k , the entire range of the gas flow from 0 to Q _{max being} evenly graded in this case. Each stage is 1/15 of the maximum gas flow Q _max .

The control unit 4, which coordinates the opening and closing of the solenoid switching valves 11, 21, 31, 41 in regulating the gas flow and thus the heating power, has 16 switching positions S _m for the simplest, clear and safe operation of the burner 2 by the user . Each of these switching positions corresponds exactly to one of the possible combinations of the open and closed positions of the four solenoid switching valves 11, 21, 31, 41. In the example shown, the control unit is a "touch control panel", the 16 switches of which can be actuated by simply touching them assigned to one of the combinations. In this way, it is possible for the control device 4 to automatically implement the switching position selected by the user in a predetermined manner into the corresponding combination of open and closed solenoid valves 11, 21, 31, 41 and thereby generate the desired gas flow Q _m fed to the burner nozzle 3 .

In Fig. 2, the operation of the control device 4 shown in Fig. 1 with 16 switching positions S _m for the control of four different partial gas flows Q ₁ to Q ₄ with the values Qmax. 1/15, Q _max . 2/15, Q _max · 4/15 and Q _max · 8/15 explained in more detail using a switching matrix. In the switching matrix, a corresponding combination of open and closed valves 11, 21, 31, 41 is assigned to the 16 maximum possible switching positions S _{m of} the control device 4, each of which corresponds to a stage of the gas flow Q _{m which is} stepped uniformly between 0 and Q _max . A 0 in the matrix means that the corresponding solenoid valve 11, 21, 31, 41 is closed, that is to say the partial gas flow Q ₁ , Q ₂ , Q ₃ , Q ₄ is switched off. At 1, the solenoid switching valve 11, 21, 31, 41 is open, the partial gas flow Q ₁ , Q ₂ , Q ₃ , Q _{4 is} switched on.

If, for example, the user actuates the switch 6 of the touch control panel 4 shown in FIG. 1, he selects the switch position S ₇ , which corresponds to a gas flow Q ₆ of 6/15 of the maximum gas flow Q _max . This switching stage is realized by the control unit 4 by opening the solenoid switching valves 21 and 31 and closing the solenoid switching valves 11 and 41, so that the gas flow Q ₆ fed to the burner nozzle ₃ consists of the sum of the partial gas flows Q ₂ and Q ₃ .

According to the invention, however, it is not always necessary that all partial gas flows are different. Especially if it is is not necessary with the respective number Partial gas flows to the maximum possible number of levels individual gas flows can be dimensioned equally be. This has e.g. the advantage that the number of different components to be kept in stock is reduced.

Conventional gas-operated cooking and baking devices generally have nine cooking levels (a total of ten switching levels). This number of cooking stages can be achieved according to the invention, for example, by the following four partial gas flows, each based on Q _max : 1/9, 1/9, 2/9, 5/9. Other options are the partial gas flows 1/9, 2/9, 2/9, 4/9 or 1/9, 1/9, 3/9, 4/9.

3 shows an example of a switching matrix of a control device 4 for an embodiment according to the invention with four partial gas flows Q ₁ to Q ₄ , in which two partial gas flows are the same (1/9, 1/9, 2/9, 5/9). In this case too, the switching matrix sets the switching position S _m selected by the user via a combination of open (1) and closed (0) solenoid switching valves 11, 21, 31, 41 into a gas flow Q _m corresponding to the switching position and supplied to the burner nozzle 3, which results from the sum of the respective partial gas flows Q _k . In this way, the usual number of nine cooking levels in conventional gas-operated cooking and baking devices can be advantageously realized.

It may also be advantageous if the gas flow Q _m fed to the burner nozzle 3 in the cooking area (which is generally at level four in the case of nine cooking levels) can be regulated more finely by means of intermediate stages in order to adjust the heating power in this area in a finely metered manner. In order to improve the embodiment according to the invention for nine cooking stages described in FIG. 3 from this point of view, a fifth solenoid switching valve 51 with the associated throttled fifth partial gas flow (1/2) * (1/9) = 1/18 = (0.5 ) / 9 can be provided. 4 shows a switching matrix of a switching device 4 for such an embodiment according to the invention. It can be seen that the combinations of the open and closed positions of the solenoid switching valves 11, 21, 31, 41 correspond to those of the corresponding solenoid switching valves of FIG. 3. Only in the cooking area between 2/9 and 6/9 of the maximum gas flow Q _max , corresponding to cooking levels 2-6, can intermediate cooking levels 2.5 / 3.5 / 4.5 / 5.5 be selected by the user, which are thereby achieved that a partial gas flow Q ₅ with the value (0.5) / 9 is additionally connected by the control unit 4 to the combination of open and closed magnetic switching valves known from FIG. 3 via the magnetic switching valve 51.

It should be noted that in this embodiment the maximum sum of the partial gas flows is purely arithmetically (9.5) / 9, that is to say greater than Q _max , when all the solenoid switching valves 11, 21, 31, 41, 51 are open. The gas flow Q _max which actually occurs when all the solenoid switching valves are opened will of course not be greater than the maximum gas flow Q _max predetermined by the flow resistance of the burner nozzle 3, since the device according to the invention reduces the gas flow in a defined manner but does not increase it.

In the embodiment according to FIG. 5 there are three throttle elements 15, 25 and 35 connected in series in the gas supply line 1. The choke resistances of the individual choke elements are preferably different. For example, you can be dimensioned so that the burner nozzle 3 of the burner 2 supplied via the burner feed line 5 Gas flow by switching on one throttle element is reduced to 3/4 or 1/2 or 1/4. When switching the gas flow is from two or three throttle elements on one by the product of the above shares given part of the maximum gas flow reduced.

For switching the respective throttle elements on and off are these switching elements 14, 24 and 34 in parallel switched. When opening a switching element, the flows Gas flow unhindered by that acting as a bypass 16, 26, 36 Switching element, so that the associated throttle element does not reduce the gas flow. For example when opening the switching element 24, the throttling the throttle element 25 out of function and the gas flow provided the throttle elements 14 and 34 are closed are throttled only by the throttle elements 15 and 35.

The switching elements 14, 24 and 34 are common Control device 4 controlled by means of which the desired Heating power is adjustable. To switch off of the gas flow is an additional one, in the burner supply line 5 or preferably the gas supply line 1 used Switching valve, which is not shown, required. This can be done, for example, to monitor the Extinguishing the flame uses existing solenoid valve will.

Claims (25)

Device for the controlled gradual reduction of the gas flow Q fed to a burner nozzle (3) of a gas-operated cooking or baking device via a gas feed line (1),
characterized in that it has a branching of the gas feed line (1) into a number n partial gas lines (10, 20, 30, 40) connected in parallel, by means of which the burner nozzle (3) each has a partial gas flow Q _k with k = 1,2,3, ... , n can be fed, and each have a control element, the control elements are each connected to the gas feed line (1) on their gas inlet side and to the burner nozzle (3) on their gas outlet side and each have a switching element (11, 21, 31, 41) for switching the partial gas flow Q _k and on flowing through them on and off Throttle element (12,22,32,42) for throttling the partial gas flow Q _k flowing through it and the switching elements (11,21,31,41) can be switched on and off depending on the selected heating output. Device for the controlled gradual reduction of the gas flow Q fed to a burner nozzle (3) of a gas-operated cooking or baking device via a gas feed line (1),
characterized in that it has a number n control elements which are connected in series in the gas supply line (1), and the control elements each have a throttle element (15, 25, 35) for throttling the gas flow flowing through them and one to the throttle element (15, 25 , 35) have a switching element (14, 24, 34) connected in parallel for switching on and off a bypass (16, 26, 36) to the throttling element (15, 25, 35), and the switching elements (14, 24, 34) optionally , depending on the selected heating output, can be switched on and off. Device according to Claim 1, characterized in that the flow resistances of the n control elements, in particular the throttle elements (12, 22, 32, 42), are dimensioned such that at least two partial gas flows Q _k are different from one another. Device according to claim 3, characterized in that the flow resistances of the n control elements are dimensioned such that the n partial gas flows Q _k with k = 1,2,3, ..., n are essentially a sequence with the values Q k = Q Max · 2 k-1 / (2nd n -1) form, where Q _max denotes the maximum gas flow Q which is supplied to the burner nozzle (3) when all n switching elements (11, 21, 31, 41) open. Device according to claim 4, characterized in that the number n of partial gas lines (10,20,30,40) n = 4 is the partial gas streams and Q _k substantially the values Q _max * 1/15 Q _max · 2.15 Q _max 4/15 and Q _max.8 / 15. Device according to claim 5, characterized in that the number n of partial gas lines (10,20,30,40) n = 3 is the partial gas streams and Q _k substantially the values Q _max • 1/7, Q _max · 2/7 and Q _max . 4/7. Apparatus according to claim 4, characterized in that the maximum deviation of the partial gas flows Q _k from the exact gradation is less than ± 20%, preferably less than ± 15%, preferably less than ± 10% and particularly preferably less than ± 5%. Device according to claim 1, characterized in that the throttle elements (12, 22, 32, 42) are connected downstream of the switching elements (11, 21, 31, 41) in the direction of flow of the gas. Device according to claim 1 or 2, characterized in that the switching elements (11, 21, 31, 41; 14, 24, 34) can be switched on and off by means of a common control device (4). Device according to Claim 9, characterized in that the control device (4) has an integer number i of discrete switching positions, each of which is assigned a combination of the open and closed positions of the n switching elements (11, 21, 31, 41; 14, 24, 34) is. Device according to Claim 10, characterized in that the number i of the switching positions of the control devices (4) is 2 ⁿ , the switching positions each being exactly one of the possible combinations of the open and closed positions of the n switching elements (11, 21, 31, 41; 14 , 24,34) is assigned. Device according to claim 11, characterized in that the combinations of the open and closed positions of the n switching elements (11, 21, 31, 41; 14, 24, 34) result in a sequence of m = 1, 2, 3, ..., 2 ⁿ consecutive switching positions S _{m is assigned to} the control device (4) in such a way that the gas flows Q _m fed to the burner nozzle (3) form an ascending or descending sequence which essentially contains the values Q m = Q Max · (M-1) / (2nd n -1) assumes. Device according to claim 12, characterized in that the maximum deviation of the gas flows Q _m from the exact gradation is less than ± 20%, preferably less than ± 15%, preferably less than ± 10% and particularly preferably less than ± 5%. Apparatus according to claim 1 or 2, characterized in that at least one switching element (11,21,31,41; 14,24,34) is designed as a binary solenoid switching valve. Device according to claim 1 or 2, characterized in that it has an electrical circuit for gradually increasing and / or decreasing the electrical control current of the switching element (11, 21, 31, 41; 14, 24, 34). Apparatus according to claim 1 or 2, characterized in that at least one of the throttle elements (12,22,32,42; 15,25,35) has a fixed flow resistance. Apparatus according to claim 16, characterized in that the throttle element (12,22,32,42; 15,25,35) is designed as a capillary, capillary tube, nozzle or tube constriction. Cooking or baking device, in particular gas stove, gas hob, gas hob or gas oven, characterized in that it has a device according to one or more of claims 1 to 17. Method for the controlled gradual reduction of the gas flow Q fed to a burner nozzle (3) of a gas-operated cooking or baking device via a gas feed line (1),
characterized in that the gas flow Q is divided into a number n partial gas flows Q _k connected in parallel with k = 1, 2, 3,..., n, each of which is influenced by a control device, the control elements are each connected on their gas inlet side to the gas supply line (1) and on their gas outlet side to the burner nozzle (3) and each have a switching element (11, 21, 31, 41) by means of which the partial gas flow Q _k flowing through them is switched on and off and a throttle element (12, 22, 32, 42) by means of which the partial gas flow Q _k flowing through it is throttled, and the switching elements (11,21,31,41) can be switched on and off depending on the selected heating output. Method for the controlled gradual reduction of the gas flow Q fed to a burner nozzle (3) of a gas-operated cooking or baking device via a gas feed line (1),
characterized in that the gas flow Q passes through a number n of control elements connected in series in the gas feed line (1), in each case a throttle element (15, 25, 35) for throttling the gas flow flowing through them and a throttle element (15, 25, 35) in parallel have switched switching element (14,24,34) for switching on and off a bypass (16,26,36) to the throttle element (15,25,35), and the switching elements (14,24,34) optionally, depending on the selected heating output can be switched on and off. A method according to claim 19, characterized in that the gas flow Q is divided into at least two different partial gas flows Q _k . A method according to claim 21, characterized in that the gas flow Q is divided into a number n partial gas flows Q _k with k = 1,2,3, ..., n, which is essentially a sequence with the values Q k = Q Max · 2 k-1 / (2nd n -1) form, where Q _max denotes the maximum gas flow Q which is supplied to the burner nozzle (3) when all n switching elements (11, 21, 31, 41) open. Method according to Claim 22, characterized in that the partial gas flows Q _k deviate from the exact gradation by less than ± 20%, preferably less than ± 15%, preferably less than ± 10% and particularly preferably less than ± 5%. Method according to claim 19 or 20, characterized in that the n switching elements (11, 21, 31, 41; 14, 24, 34) are switched on and off by means of a common control device (4). Method according to claim 19 or 20, characterized in that the n switching elements (11, 21, 31, 41) are controlled by a control device (4) which has an integer number i of discrete switching positions, each of which is a combination of the open and closed positions the n switching elements (11,21,31,41) is assigned.

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