DE2624279A1 - THERMAL METAL PROCESS AND FURNACE FOR GAS OR LIQUID FUELS - Google Patents

Description

COJHAUSZ & FLORACK

PATENT AGENCY OFFICE D-4 DÜSSELDORF. SCHUMANNSTR. 97

PATENT LAWYERS:
Dipl.-Ing. W. COHAUSZ Dipl.-Ing. W. FLORACK ■ Dipl.-Ing. R. KNAUF ■ Dr.-ing., Dipl.-Wi.tsch.-lng. A. GERBER Dipl.-Ing. HB COHAUSZ

May 26, 1976 3ervice National ciifc:

QAz Dj ^ AiTGj; 2624279

23, rue Philibert D lEßPKd
F -73d7 Paris

V. technical procedure and oxen for gaseous or liquid fuels.

The present invention concerns a thermal process in a furnace with firing for gaseous or liquid fuels, which has at least two heat sources, one of which is located in the lower part and the other in the upper part of the furnace.

Oie: .rfinvun. · Applies equally to a furnace for gas-pure or liquid fuels, which ¹ particularly allows the use of OGS mentioned above; η process.

The present invention is applicable to thermal engineering processes in industrial ovens, for example for heating, for cooking or burning, for annealing or for drying parts that are fixed or in motion in the oven, and in particular drying Guüfornien and Kernels. "The present invention. Is equally applicable to the cooking of food in the domestic stove, and in general it is applicable to thermal engineering processes, which are referred to below in the general form" cooking ", and which emanate from thermal impulses of low inertia on small pieces.

In the cooking ovens there is usually a distribution of the AZ. ^ Q 179 - 2 -

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'Temperatures that generate an increase in heat, aem calculation must be borne in order to induce cooking according to the liatur of the 'parts that are to be cooked are to be ensured. So it is necessary, depending on the case that the ivory root, which comes from the upper region of the furnace, larger or smaller than that which comes from the lower kegion. According to the known method for Cooking food, these conditions of cooking are realized either by acting on the position; of the food or by changing the temperature curve by means of a guide plate for the amount of heat, which is conventionally inside the furnace.

According to the known methods, however, in order to obtain a suitable control of the heat flow, the it allows to arrange the distribution of the temperature necessary for cooking the food, an oven of relative to provide significant dimensions, so especially the collection and concentration by the guide plates sufficient thermal flows guaranteed.

The invention overcomes these drawbacks and particularly aims at a method in a furnace - muffle furnace or not - that makes it possible to create different degrees of heat without guide plates to different Obtain distributions of temperatures, each of which is related to the cooking of a food or a particular one Partly adapted, even if the furnace is only relatively small, and this method it also makes it unnecessary to change the position of the parts to be cooked in the oven.

To this end, the cooking method mentioned above is the one mentioned above was and that is according to the invention, characterized in that the temperature and the heat supply aes Oven controls with a thermostat that controls with a ZeiO control device cooperates during a cooking period and following a predetermined program, whereby the operation according to the "aJjes or nothing" scheme of at least one of the

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The heat generator follows the consecutive switching steps, in the course of at least one of the heat generators is consequently put into operation and switched off in succession.

Go allows this new procedure in a continuous manner; Different temperature distributions during the cooking time to create in the oven without guide plates, so · it now is no longer necessary, have large volume ovens to have to.

Jeae heat distribution ;; can be regulated by the Heat flow emanating from any heat source is given an appropriate value, i.e. a value which is the maximum Heat flow or a part of this flow corresponds, with the stability of the temperatures automatically through the thermostat is reached.

Ξ, '8 is an advantage if you want to regulate the cooking temperature uses a thermostat which is suitable to control the heat sources according to "all or nothing".

According to a characteristic of the invention, amn can regulate the relationship between the heat flows of different heat sources to a predetermined value by turning off at least one of the heat sources. starts up again. This way of regulating the heat flow of the heat sources and the relationship between them by "all or nothing" has the particular advantage of not having to use heat sources - or burners - of great adaptability of the work-in- essence ; Thanks to the invention, it is now sufficient that these heat sources only have to be provided for working with a single, immediate delivery of fuel.

In order to ensure that the oven is before the actual cooking time comes up to temperature quickly, it is advantageous to first continuously heat with all "..heat sources until the pre-determined cooking temperature has been reached, and then

_ 4 6 C ν -1 ^r > Π / 1 Π 8?

during: to continue the cooking time so that one removes the heat sources lets work in an interrupting manner.

An advantageous property of the / invention is that you turn the heat sources on and off at the same time every time one of them is in a given one Number of cases had been turned on and off. So you put two heat flows in a mutually predetermined one Relationship.

This method is advantageous in a furnace for liquid or gaseous fuels, which is a carrier for the food included, applied, this oven according to the invention containing: at least two heat sources, each of which is connected to its own control device for "all or nothing", a thermal control device after "all or nothing", the output of which is connected to at least one of the control devices, and a programming device. This programming device includes a thermal control device connected temperature control device, a device for selecting the cooking time and a device for selecting the ignition rhythm, which is connected to the output of the thermal control device and to at least one of the Control devices can be connected to determine the periods of operation or non-operation of the heat sources, which are connected to this control device via signals from the thermal control device go out.

In this furnace one can control the device for selecting the ignition rhythm of the program device by output signals by output signals of the thermal control device through "all or nothing". This property shows the advantage of simplifying the program setup as well as the _? allow the thermostatic stabilization of the various temperatures prevailing at various points in the furnace.

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It is evident that in order to obtain this stabilization, the function instructions given by the program direction given to the heat sources of the furnace must be periodic, i. e. that the mean of the Heat output delivered by these heat sources during a cycle; must be constant in time, whereby the condition is only reliably valid in the absence of sudden calorie loss, e.g. at the moment of opening the furnace.

Other features and advantages of the invention result from the description of an oven for cooking food, which is described below as an exemplary embodiment but not limiting is given with reference to the accompanying drawings, in which:

Fig. 1 is a vertical schematic section a muffle furnace according to the invention isu;

Fig. 2 is a block diagram of the thermal control device and the electronic programming device of the furnace according to the invention;

Fig. 3 shows the electronic structure of the control circuit of the electric valves of the furnace and

Fig. 4 shows the electronic structure of the device for Selection of the cooking time according to the preparation method of the dish and possibly its weight shows.

Figure 1 shows a muffle furnace, i.e. a furnace which is provided with double walls: an inner ', vand 1, the enclosing the cooking space 2, and an outer wall 3; between the lower inner walls 1a and the outer wall 3 Pipes with gas burners 4 are stored, aie directly mounted under the lower part 1a of the inner wall 1; are. At the upper part 3a of the outer wall 3 in FIG Group of burners with individual burners of this type arranged.

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which are called "radiating surfaces". The burner rows 4- as well as the burner 5 are z. B. designed as an outdoor burner. You can of course also use so-called burners with secondary air. In this case, however, the space which is enclosed by the inner walls 1 and the outer walls 3 must be sufficiently ventilated. The burner tubes 4 are connected through the interposition of a common supply line 6 with a source of combustible air / gas-gas (not shown). The burners 5 are connected in the same way to the source of the combustible air / gas mixture by a common supply line 8. Inßeder of the supply lines 6, 8, an electric control valve ⁵ in Figure 1 (not shown) is provided, whose purpose itfira described later. The burners of the tubes 4 as well as the burners 5 are provided with suitable ignition devices, for example with ignition flaisms or electrical spark plugs (not shown). The partition _{walls 9 5,} which are each formed by the upper extension of a side part 1b, 1 £ of the inner wall, separate the space between the walls 1 and 3 of the furnace into two combustion chambers 10 and 11, one 10 of the burner tubes 4 and the other 11 the Burner 5 included. The chamber 10 is connected to the outside space by means of lateral openings 10a which lie in the upper part of the outside wall 3 of the furnace, while the chamber 11 is connected to the outside space via an opening 11a which lies in one of the front parts of the outside wall 3. Provision could else other separate heated compartments "-o could the combustion chamber 10 into three compartments divided v / ground, for example by using lower extensions of the side wall 1b_ and 1JC in the same V /.

On the side walls 1b, 1c, is inside the cooking space 2 a carrier plate 2a. attached, which is intended to accommodate the prepared food. >; s is It is also possible to use this plate 2a with a drive device that allows it to be put in the oven or pulled out before or after cooking.

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The combination of an arrangement shown in FIG. 2 ultimately acts on two electric valves 21, 22, which both control the supply of the combustible mixture to the burner tubes M of the furnace and also to the burners 5. These solenoid valves 21, 22 are controlled by "all or nothing" with the aid of two power amplifiers 23 and 24. The amplifier 23 _}, which is connected to the electric control valve 21 of the burner tubes 4- at the bottom of the furnace, is normally directed by a comparator 25, the output voltage of which fluctuates to both sides of a reference value, depending on the input voltage from the temperature probe 26 located in the cooking space 2 near the hotplate, is higher or lower than the value of the reference voltage, which is based on a üJ Temperatur-Programmierungseinrichtung 27, which acts as a voltage divider of a constant voltage that comes from a voltage source 28. The comparator 25 and the probe 26 form a temperature regulating device to which the reference temperature is supplied from the programming device 27 of the program input #. The reference voltage, which corresponds to one of the types of preparation designated by A to N, can be selected by pressing one of the buttons 29 of the program input; each button 29 also controls simultaneously the corresponding contact of a selection device for the ignition rhythm of the fire JO and the corresponding contact of a preselection device for the cooking time 31 or 38. The buttons are self-locking, and pressing a button brings the others back to the rest position.

The program input6 also offers the advantage of a changeover switch 32, which is operated by hand, the replacement of a member for manual programming of the temperatures on the automatic programming device for temperatures 27 at the input of the comparator 25. The In the position of the switch 32, which is not shown in FIG. 2, the voltage source 28 supplies a potentiometer 33, its sliding contact for manual adjustment

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the equivalent stress for the theoretical high temperature gives; the actual cooking temperature is determined by the temperature sensor 26 measured.

In the second place, the output of the comparator 25 is connected via the line 34 to the device for rhythm selection ÖO of the program input. This rhythm selection device 30 contains a certain number of numerical dividers which can send out a pulse or an output signal (voltage); all the η pulses that are received at the input (n is generally between 1 and 10), and are delivered at its output 35 corresponding to the pressed key 29, act as an "all or nothing" voltage on the input of the power amplifier 24, the the solenoid valve 22 is supplied. Incidentally, this rhythm selection presetting is shown in detail in FIG.

The voltage appearing on the output line 35 is in phase and of the same duration as the voltage appearing on the output of the comparator 25, but it only occurs when all η of the output voltage of the comparator are present and on the input of the amplifier 24 act. On the other has a changeover switch 36 has a simple and a double contact, one of these twin contacts between the input of the amplifier 24 and the output of the rhythm selecting means 30 is provided and the other between the input of said amplifier and the output of the K _o mparators 25 lies. The single changeover contact 36 is located between the input of the amplifier 23 and the output of the comparator 25.In this way, the amplifier 24 for a position of the changeover switch 36 is controlled by the rhythm selection device 30 and the amplifier 23 is controlled by the output of the comparator 25 controlled, whereas for the other position of the switch 36 (which is not shown in Figures 2 and 3) the amplifier 24 is controlled by the output of the comparator 25 and the amplifier 23 is not controlled. So remains in the not shown position of the

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switch 36 the solenoid valve 21, which the supply of the Burner 4 at the bottom of the furnace controls, always closed when, - as. You ktroventil 22 to the rhythm of the output signals of the comparator 25 is subject to which are controlled by the temperature of the Kochr ^ umes 2, the tempe rature, the ouch. the probe 26 is determined.

In the third place, the cooking time program is implemented with the aid of the device for selecting the cooking time the Programmiervorrich'Gung, a device that is similarly controlled by a number of buttons 29 and the output after a period of time corresponding to a multiple of a time period determined by a timer 37 gives a signal. This timer 37 is independent and when the program it requires (positions I to N of the buttons 29), one sets a cooking time selector 38 ingang, which is independent of .Vählvorrichtun "31 is, and on which the weights of the Specifies food to be cooked with the help of the buttons 39, which are divided according to increasing weights (in half a kg).

The selected cooking time is transmitted by a signal that which comes from one of the dialing devices 31 or 38, una in a member 40, which transmits a command for the beginning and the end of the cooking time to the relay 41, that selects the commands related to the starting and stopping elements of the electrical supply 42, to warnings 43, and possibly, if it is present, on a motor 44, which brings about the retraction and extension of the food in the oven are to be given. This Motor 44 can be operated by hand via a changeover switch 45 which allows the motor to be connected directly to the electrical network. A special key that inhibits all buttons of the program device, controls the preheating of the oven by igniting the at the same time Breoner tubes 4 and the burner 5 · The switch 66 switches the two amplifiers 23 and 24 in parallel, which the Control solenoid valves. A switch 67 connected to the the previous one is permanently connected, the logic voltage switches

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the control supplied by the comparator £ .5 a Umkegr logic for Verrie gelung 68, which the warning 43 triggers when this tension disappears, i.e. when the oven is hot.

In Figures 3 and 4, the programming device for the temperature 27 has been shown in more detail and also on the one hand the selection device for the Zünarythmus 30 and on the other hand the selection device for: the cooking time _o As can be seen from Figure 3, the device is for the "Temperature selection 1-7 with a constant voltage source 28 connected via zv / ei leads + V -V, between which two Zener diodes 46 and 47 are. The assembly of electronic devices consists of integrated circuit elements (IC) of high Noise immunity, so that it is protected against the effects of parasitic superimpositions that can penetrate via the supply into a sector which itself is also provided with an anti-interference filter.

Dea? Temperature sensor 26 is a wire probe made of platinum, which is used to supply them with direct current with an inde with the common point M between diodes 46 and 47 and at the other end to the source + V with the interposition of a resistor 48 with a large V: ert in relation to which the probe 26 is connected so that it works with constant current. The DC voltage applied to the ; _nd the probe 26 is present, through the interconnection of a resistor 49 to the Kipp-r. 'input of the comparator amplifier 25.

The stable input of the comparator amplifier 25 receives the reference voltage which is supplied by the device 27 via the interposition of a resistor 50. At this stable input is a negative feedback through a resistor 51 is formed, inserted which connects the J input of the comparator amplifier 25 to this output couples to provide an adjustable characteristic for the

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To get the stimulus threshold of the Pendän of the comparator 25.

The device 27 has the resistors 52 to 52, which are connected in series with the point M and those with direct current via the contacts;: - 3 ^ to 53 of the switch row that the buttons 29 has according to the program of the selected temperatures can be supplied. Of the common point of this switch row is with the supply + V with the interposition of a changeover switch 32 and one Resistance 5 ^ connected.

The manually adjustable potentiometer 33 is with a End connected to point M, and its sliding contact can be connected to supply + V if the switch 32 is in its position not shown in FIG. The switch 32 allows the resistors 52 ^ to 52 through the adjustable resistance of the potentiometer 33 to replace the test voltage on the comparator 25 to give.

The output voltage of the comparator 25 is as long as the 'value + V, as the voltage at the leads of the probe 26 is below the reference voltage. The output 55 of the comparator 25 is connected to the counting input of a binary counter GB1 which is part of the rhythm selection device 30 and which operates as a frequency divider. A signal appears at the outputs S2, S4, S8 of the binary counter, respectively. every 2, 4 and 8 pulses emanating from the comparator 25, i. e. all the 2, 4 and 8 times when the value of the voltage on the leads of the probe 26 falls below that of the reference voltage. The outputs S2, 84 and S8 are connected to the inputs E., E ~ and E, of a gate ET1 with the interposition of the resistors 56, 57 and 58, the fourth input E _{Q of which is} either connected to the output 55 <3- © s comparator 25 or is connected to ground via a changeover switch 61.

The rhythm selector for the burning time 30 has the

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Contacts 61 _Q , 61., 61p, 61,., Each of which can be switched on with a button. When the contact 61st is switched on, it connects the supply + V to the inputs E ^, Ep and S _>; of the gate S ¥ 1 with the interposition of three diodes 60. When the contact 61 ″ is switched on, it connects the supply + V to the inputs Ep and S ^ of the gate ΕΪ1 with the interposition of two diodes

60, and if finally the contact 61 ^ switched on it connects a diode 60 under ZxcLsctu-n circuit the supply + V with the input E-, the gate ET1.

The output of the gate ET1 is connected to the amplifier 24 with the interposition of a double-pole switch 36, and the output 55 is cLes comparator 25 with the amplifier 23 via the single contact of the switch 36 connected, the amplifier 24 controls the Excitation of the coil 64 of the EIe ktroventils 22, which from the supply line 8, which leads to the burners 5, is mounted, whereas the amplifier 23 is the excitation controls the coil 62 of the solenoid valve 21 mounted on the supply line 6 that connects the burners 4- am Bottom of the furnace leads.

ΐ / hen the contact 61 _Q output 55 to the input E _'o of the gate ET1 connects (such geze in Figure 3 IGT), and call the switch 36 on the one hand the output to the amplifier 25 and on the other hand, the output of gate ET1 connects to the amplifier 24; (as shown in Figure 3), amn can achieve that four burning time segments after the transmission of the pulses emanating from the comparator 25 and corresponding to the positions of the contacts 61.,

61 ο and 61 -, can be obtained.
d 3

When the contact 61 ,, is closed, a voltage + V is constantly applied to the inputs Ξ. , E ₀ and E, of the gate ET-1. As soon as the voltage at the output of the comparator 25 fluctuates around the value + V, it acts on the input E "via the contact 61 ^, and a signal appears at the output of the gate ΞΪ1, this causes a simultaneous ~ ^rr * ^iU ^ 609850/1082 - 1? -

Ignition of the burners 5 and the burner tubes 4 on the ground receives, or ignition rhythm "1".

',' when contact 61 _{0 is} closed, there is always a voltage + V at the inputs Sp and E- of the gate. '^T;'L'1, whose input iiL is then connected solely to the output Sp of the binary counter CB1. This gives an ignition rhythm that is derived from the sequence of ignition only of the burner tubes on the floor, then simultaneous ignition of the burner tubes 4 on the floor and the burner 5 ·> then ignition of only the burner tubes on the floor, and so on. This rhythm of ignition is named rhythm "2" below.

If a contact 61 ~ is closed, it is permanently o a voltage + V only at input 3 of the EODI gate, its .inputs "5. and ^ only with outputs Sp and S ^ des binary counter CB1 are connected. You then get one ^ ybhmus of ignition, consisting of three successive ignitions only the burner 4 on the ground and then one simultaneous ignition of the burner on the Boben and burner iv, then three consecutive ignitions of only the burner put together on the floor and so on, read the rhythm of the Ignitions is referred to below as rhythm "4".

; finally, no hen the contacts 61, 61 _o, and is closed, you get a rhythm on the ignition, rhythm "8" called, only the burner 4 followed from the series of seven successive firings at the bottom of one! simultaneous ignition of the burner 4 on the ground and the burner 5 composed.

By operating the switch 61 _Q , be it by hand or using one of the program input buttons, the input .CL of the gate i7 £ 1 is connected to ground, which then no longer conducts. The burners 4 on the ground are set in motion in the rhythm of the impulses supplied by the comparator, and one is obtained

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Rhythm of ignition called the "S" rhythm.

By operating the manual switch 36 you can connect the amplifier 24- directly to the output 55 of a comparator 25 and at the same time switch off the input of the amplifier 25 and a rhythm of ignition called the ¹¹ G "rhythm is obtained.

Of course, the possible number of ignition rhythms; not limited by what has just been described became; this number could be increased by the fact that the capacity of the binary counter CB1, the number of Inputs of the gate: 5T1 and the number of contacts 61 enlarged.

The details of the construction of the devices for the cooking time selection are shown in Figure 4-. The time base 37 is formed by a multivibrator whose period is e.g. 2.35 seconds. The output of the time base 37 is with the counting input of a binary counter.-; CB2 connected, its output S-, ~, which is the frequency of the time base 37 divided by 16, is connected to the counting input of another binary counter 0B3.

33 counting input of a fourth binary counter CB4- is connected to the dialing contacts of the time base 7o, 7% 72, which are operated by "Pastes 29" program input and which allow different basic cooking times to be obtained. When contact 70 is closed, connects he the output, which divides by 8, S'g of the counter GBy with the input of the counter CB4. This output S'g of the counter CB3 gives a basic time of 300 seconds, which is needed in the majority of cases,

The contact 71 connects, when it is closed, the output S ¹ ^ ₆ dividing by 16 of the counter CB ^ with the input of the binary counter CB4-, the output S ¹ ^ g

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gives a bottom time of 600 seconds.

o- ¹

When the double contact 72 is closed, it connects the output S ¹ ^ -, which divides by 16, with the Singang of CB4 and likewise the fourth input ^ '^ of a gate ET 2 (NON = NAND according to the symbols of the figures 3 and 4 and according to the functional description) with the voltage supply + V. This gate ΞΤ2 receives at its other inputs E '^, 2'p, E ¹ _A, the output signals S'oi S'g and S'g of the binary counter CB3, which divides by 2, 8 and 16 to at its output To generate a signal which acts with the interposition of the resistor 80 on the inputs RAZ of the counters CB2 and CB3 and which is intended to bring them back to the logic state "O". This makes it possible to achieve a basic wiping time of 26/32 of 600 seconds, that is about 500 seconds, since the counter 0B2 is reset to "0" every time it has received 26 pulses. Other combinations are possible.

The binary counter CB4- generates output signals second Order associated with the output of the counter CB3, the is adapted by an inverter (Negatör) 73, if the nature of the logic integrator circuit used requires this, on a matrix of contacts 7 ^, <eie five Has inputs ME1 to ME5 and two outputs MS1 and MS2, works ·.

The output of the inverter 73 is connected to the input ME1 and the outputs of the binary counter 0B4 are connected to the inputs ME2 to ME5 connected. These two outputs MS1 and MS2 act on two inputs of a gate ET3 1 which supplies an output signal if the Combination of two logical states "one" appears, which is created by the combination corresponding to the contacts of the Matrix 74- can be determined.

It should be noted that in this way all combinations of a state "one" or of two states "one" are obtained

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between the five bits of the tweiten order, which is sufficient for the present problem Man _o the number of inputs of the gate ET could achieve all possible combinations of 3 contacts at five with a matrix 74 having about 20 upon expansion.

The output of the gate "ST3" controls an amplifier 75 which controls the cut-off relay 41, the contacts of which transmit all commands to terminate the cycle via the lines 76, 77, 78, which lead to the common electrical supply 42, to the camouflage 43 and to the motor 44 »At the beginning of the cycle, a common reset to" 0 "of all binary counters CB1, CB2j CE3, CB4 is controlled by applying their inputs to ground and the reset to" 0 "RAZ with the help of contact 79® i ^; s is closed remember that the NAND gate ET 2 only resets the counters GB2 and CB3 to "0" at each cycle of 3OG, 600, 500 seconds programmed through the contacts 70 ^ 7 ^? 72. The diode 81 and the: Resistor 82 are intended ₉ to avoid repeated application to ground and ground adaptations of the impedance »

The matrix of contacts 74 is included in the device 31 for fixed cooking time selection. If you want to cook as a function of the weight of the kg good, the corresponding keys 29 (I to N) of the program input act on the liJählkontakte of the base time 70, 71 and 72 and on the inverter 83, which the output of a gate ET4 with the The input of the amplifier 7 ^> connects instead of the output of the gate ET3- The two inputs of the gate ET4 v / ground through the outputs MS ', MS'ρ of a contact matrix 84 with five inputs and two outputs, whose inputs are influenced as with the matrix 74, to the outputs of the counter CB4 and the inverter 73 are connected. This matrix 74 is controlled by the selection device for the hole time, which is variable as a function of the weight 38, and gives the combination of the logic states “one” corresponding to the keys 39 ₅

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the e.g. in 0.5-1-1.5-2-2-2.5-3 kg gradually are increased.

The electronic program input just described allows automatic control of a kitchen, for example, to be implemented by using aen ϊ, γρ of the food β (A to N;) with just one key 29 and nö "ci"; enfallr. its weight by means of a button 39 "Ibo. It can be specially adapted to a muffle furnace with row control, which has been described above but can also be used for a normal oven.

The essential principle is the determination of three parameters of cooking for a given preparation (A to W), which are activated by pressing a key is obtained, v; as for the automatic execution of commands that leads through the electronic program entry are given.

These parameters are: the temperature of the cooking space 2, dor type of heating, controlled by the program of the Zünärythnus the burners 4 and 5 of the furnace, and the Cooking time.

For a whole range of ways of preparing food (A. to H) these three parameters are independent of the dimensions of the prepared, in particular for flat Pastries, baked goods, etc.. The three parameters are then precisely defined and can simply be keyed in.

In contrast, is of very for other cookers different weight or volume, such as meat, αϊ cooking time a function that increases with weight, an almost linear function for each type of preparation (I to ÖT) »but with a coefficient that depends on the Proportionality deviates, which is then predetermined by pressing one of the contacts of the base time selection? Ü, 71 and 72 will. It is then necessary, on the one hand, to set the temperature and cooking program using buttons 29

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29 (I to N) and on the other hand the weight; (Key 39), that in its own way the cooking time; intended to enter.

As an exemplary example, it has summarized the relevant parameters for different / ⁷ ubereitunsarten, in the following table; several different preparations, which can match in the same parameters, have been grouped under the same type,

Know Type of temperature .Time program to seize preparation Probe ° G Minutes sequence A. Herrings
(Meringues) 120 50 B. Batter in
I ¹ O rm 170 60 1 G Tea cake 190 50 Λ

Biscuit

200

Biscuit cake

220

Cake,

Speckkuchen,

Pizza

250

Roast pork,

Lamb shoulder

Poultry,
Rabbits,

roast beef

250

250

function

of weight

"Function

of weight

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It can be seen that it is sufficient to provide a keyboard, each key of which has one or more types of preparation (o) of cooked item (s) corresponds to simultaneously specifying the three parameters for the first 'part of the table. For the second part allows an auxiliary keyboard 39? the weights of the cooked food.

Three examples of cooking in accordance with the method of the invention are given below.

1. Baking a biscuit:

Press key 29 on the program input accordingly of preparation D and programs a temperature of 200 ° C, the ignition sequence 2 and the baking time of 30 minutes. The preheating caused by the simultaneous The start-up of the lower burners 4 and the upper burners is effected quickly after about 10 minutes; the sequence of functions is then triggered automatically; the function is initially only followed by the lower burner the simultaneous operation of the lower and upper burners to return to the function of the lower burners only and so on until the end of the process, which takes 30 minutes.

2.Baking a pizza:

If the F key back by a temperature of 25O ⁰ C, the Zündrythmus 8 and the baking time of 30 minutes to program. After about 15 minutes of preheating, the functional sequence is started: it triggers the function by interrupting only the lower burner seven times, followed by the simultaneous operation of the lower and upper burners; this process is repeated for the entire duration of the baking _{or the like}

3. Cooking a roast pork of 1 PZg: Press the I key to set the temperature 25o ° C, the ignition rhythm is 1 and the base time that is started is 600 seconds. The weight of 1 kg is entered by pressing a key 39,

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which combines the contacts of the switch matrix 84 to have a cooking time of 60 minutes. After preheating the functional sequence started; he solves the simultaneous Function with interruptions of the burner tubes 4 and the burner 5.

Another advantage arises when one considers that:

- if you get an overheating effect to beautify or gratinate the food at the end of cooking If you wish, you can use the previously entered ignition rhythm without changing the position of the hotplate in the oven replace rhythm G (actuation of switch 36) and so achieve only the upper burner 5 in an interrupting function that upper heat prevails.

- x «/ enn, on the other hand, at the end of the cooking process wishes to accelerate the cooking at the bottom of the food (e.g. the bottom of a cake with a liquid Topping), you can without changing the position of the food, e.g. from rhythm "4", which sets the ignition rhythms the burner 4 triggered on the ground only three times in succession and then in a simultaneous function the burner 4 at the bottom and the burner 5 continued, go to the rhythm "S" for which the heating by the Burner 4 becomes predominant on the ground "

As can be seen from the above description of the invention, the preheating time of the furnace is shortened in Reference to that required in conventional ovens, since they are, according to the invention, by simultaneous operation the burner 4 and 5 cLes oven is reached.

Of course, the oven can have several thermostats with their thermocouples in different places of the Furnace are housed; these thermostats can each control a heat source of the oven for themselves.

Programming device is advantageously a very compact box as a building block, the front surface of which all Buttons for control and the back of the sector

6 0 9 8 5 0/1082 _ _? "

Connection parts carry the thermal probe, the electrovalves and for the system of ignition of the burners. So it can easily be attached to any type of furnace, provided that that there is attached the temperature probe and each of the two solenoid valves in series with the corresponding gas supply line is connected. The programs are set according to the function of the ovens.

The following expressions are to be understood in particular as follows: "Cooking" is understood to mean all types of heat treatments, especially technical treatments such as firing and annealing. Under an "all or nothing" rule is one Understood regulation in which the feed is either fully open or fully closed.

609850/1082

Claims (14)

il claims 1. Method of thermal treatment in a furnace that has at least two heating devices operated by gaseous or liquid fuel, of which at least one is in the lower part of the furnace, characterized in that the temperature in the furnace is by means of a thermostat and the supply of fuel to at least one of the heat sources through periodic full switching on and full switching off of the fuel supply is controlled according to the temperature determined by the thermostat and a specified program. 2. The method according to claim 1, characterized in that draws that the procedure in the event that the item to be treated for some time at a certain temperature should be maintained, begins only after this temperature by switching on all heating devices has been achieved. 3. The method according to any one of claims 1 to 2, characterized characterized in that the heating sources are switched on and off at the same time each time one of them has been turned on and off a predetermined number of times. 4. Furnace for gaseous or liquid fuel for performing the method according to any one of claims 1 to 3, characterized in that it has at least has two heat sources, each of which has a switching device by means of which it is either completely 30 179
C / Be 609850/1082 ORIGINAL! NSPECTED (H) switched or completely switched off, furthermore a control device for selectively controlling these switching devices, and a device for operating this control device according to a given program. 5 · Oven according to claim 4, characterized e t that the thermal regulation device has a comparator with two inputs and one output, one of these inputs with a temperature sensor that is installed in the oven, and the other of these inputs with the temperature program device: are connected and the Output once directly to one of the control devices and on the other to the other of the control devices Interposition of the rhythm selection device connected can be, and the device; for thermal regulation gives an output signal when the signal transmitted by the sensor is below a reference signal obtained by the Device for temperature programming is transferred. 6 »Furnace according to claim 5id.ad. Characterized by, that the device for temperature programming a voltage divider, which has several outputs, the different Can emit Bezagssignale, and a group of Umscha.cern contains to optionally one of these outputs to be connected to the precautionary measure for thermal regulation. 7. Furnace according to claim 5 »characterized in that that the device .. ^. for temperature programming a manually adjustable voltage divider una. a Changeover switch has to connect the output of this voltage divider to the other input of the device for thermal To join regulation. (in) 6 0 9 8 5 0/1082 8. Oven according to one of claims 4 to 7 »thereby marked that the device for rhythm selection a multi-stage counter, the input of which is connected to the output of the thermal regulation device is, and a group of switches has to selectively switch one of the outputs of the counting stages to one of the to connect said control devices. 9. Oven according to one of claims 4 to 8, characterized that it has switching means to control the output of the thermal regulation device on the one hand directly to one - or the first - of these control devices and on the other hand to the other or second - the control devices through the interposition of the device for rhythm selection connects in the way, a®. Cycle of simultaneous operation and standstill to control both heat sources when the connected to the said first control device heat source a has carried out a specified number of cycles of operation and standstill. 10. Oven according to one of claims 4 to 9, characterized in that that it has means of interruption to the output of the thermal regulation device to be connected only and directly to any of the control devices. 11. Oven according to one of claims 4 to 10, characterized gekennz eichnet that the Kochzeitwähl device a base time, a group of counters, whose input with the basic time is connected, and a device for temporal synchronization has that to this group of Counters is connected, which can provide a control signal to stop cooking when the count of the Counting group has reached a specified value. 12. Oven according to claim 11, characterized in that that the temporal synchronization device carries a group of contacts, the composition of which Contact positions a predetermined count of the counting 6098 5 0/1082 _(IV ) (IV) group e corresponds. 13. Oven according to one of claims 11 and 12, characterized characterized in that the device for Cooking time choice a variety of basic time sizes and one Group of switches has to optionally connect one of the basic time variables to the counter. 14. Oven according to one of claims 6, 8 and 12, characterized marked that the program input a the first group of buttons, each of which has a switch from the group of switches of the temperature programming device actuate one changeover switch of the group of changeover switches of the rhythm selector and at least one contact of the group of contacts of the device for selecting the cooking time, the oven temperature, the demand of fuel of the oven and the duration of cooking, for cooking a report made by the action of any of the Buttons is programmed, can operate. 15 furnace according to claim 14, characterized in that that at least some of the keys of the first key group actuate the changeover switch of the group of changeover switches the time dialing device to select the basic time of this device. 16 _O oven according to claim 15, characterized in that the time selection device has a second group of contacts, the composition of the contact positions corresponds to a predetermined count of the counting group, and in that the program input has a second group of keys, each of which is one of the contacts of the second group of contacts to program the cooking time of a piece according to its weight, and also to program the temperature of the oven, the amount of fuel required and a base time that is preprogrammed by a key of the first group of keys. 609850/1082 (V) • cfo 17 · furnace according to one of claims M- to 16, gekennz characterized eichnet that it is provided with a double-walled cooking space and that the ^T heat sources are constituted by burners of the type open-air burners which are housed in the space between the two walls of the cooking chamber _o 609S50 / 1082