DE10129885C1 - Process for regulating the heating power of a baking oven used in bakeries comprises integrating the difference between the theoretical temperature and the actual temperature over the baking time; and correcting the theoretical temperature - Google Patents

Abstract

Process for regulating the heating power of a baking oven independent of a baking process comprises integrating the difference between the theoretical temperature and the actual temperature over the baking time; and correcting the theoretical temperature to a time point during the course of the baking process independent of the value of the integral of the difference of the theoretical temperature and the actual temperature over the baking process. Preferred Features: The theoretical temperature is corrected in such a way that the amount of the integral is less or slowly increases during the course of the baking process. The theoretical temperature is corrected in fixed time intervals, especially every 30 seconds.

Description

The invention relates to a method for controlling the heating performance of an oven according to the generic term of Claim 1.

Pasta is used in industrial ovens of tempera individually adapted to the baked goods baked courses, so that during a typical Baking process reached different temperatures in the baking chamber become. To be able to positively influence the baking result also steam vapor during the baking process initiated the baking room.  

For loading and unloading industrial ovens different methods are used. So be in Stacked ovens separate the trays with the baked goods ovens stacked one above the other. Be in rack ovens Rack trolleys in which a variety of sheets of dough blanks can be accommodated as a whole in the Rolled oven. There are also smaller ovens for the Known for use in bakery stores where several ble by hand into a single oven chamber be inserted.

Simple oven controls regulate the temperature of a Oven after a target temperature curve, the z. B. empi for a full oven and a certain baked good was set. The following baking cycles will then follow controlled this target temperature curve in such a way that the actual temp. continuously or at short intervals temperature in the baking chamber with the respective target temperature is compared. If the actual temperature is below the target Temperature, the heating source is put into operation or kept in operation; is the actual temperature heating at or above the set temperature, the heating source switched off.

From DE 195 11 621 C1 an oven control is knows, in which a fully loaded oven first after a The target temperature curve is controlled and the actual Temperature curve measured and saved in the baking chamber becomes. For all baking cycles following this "learning phase", especially for those with less occupancy of the Oven, the saved actual temperature curve is considered new he is based on the target temperature profile.  

From DE 198 39 008 C2 an oven control is knows, in which a fully loaded oven first after a The target temperature curve is controlled and the actual Temperature curve is measured and saved. After Ab At the end of this "learning phase" is the saved actual temp ratur history over the baking time and integrated as a target-in tegal value saved. For everyone on this "learning phase" fol baking cycles, especially for those with low occupancy of the furnace, the integral of the Actual temperature over the past baking time det and compared with the target integral value. The backvor gear is canceled as soon as the actual integral value Target integral value exceeds.

A disadvantage of the aforementioned methods is that they not or only insufficiently due to changes in the external loading conditions of the furnace. Fluctuations in the Schwa supply, different temperatures of the dough blanks when shooting in, different occupancy of the Oven, exchange of the rack trolley or relaxation the door seal lead to changed conditions in the Baking space and thus also to different baking results sen. Consider the static procedures above these changes either not, or only in one low mass using a reference baking process. This Reference baking requires one in a "learning phase" fully loaded oven.

Based on this state of the art, the present the invention is therefore based on the task, a Ver drive to specify the genus mentioned above, that too  even with different furnace loads Total baking result enabled and independent of the outside Conditions and without a "learning phase" a reliable Operation guaranteed.

According to the invention, this object is achieved by a method solved the features of claim 1.

The method according to the invention ensures one of the Allocation of the oven independent baking result. The procedure continues to deliver even with changing external conditions for example B. in a different maintenance condition Door seals or a different amount of steam supply an even baking result. In addition, one "Learning phase" of the oven with full or partial load due to the adaptive to the respective conditions fit baking process not necessary.

Accordingly, the oven is based on a predetermined The target temperature curve is regulated and at the same time the Actual temperature measured in the baking chamber. The deviation of the The actual temperature from the target temperature is continuous integrated over the course of the baking process. The int gral of the deviation of the actual temperature from the target temperature rature can be seen as a measure of the energy difference between the energy given by the target temperature profile and the actual energy of the actual tempera supplied to the baked goods the course of the door. The target temperature is then at a specified time depending on the value of the inte corrected grail. After this new target temperature then the heat source as the baking process continues controlled.  

In an advantageous embodiment, the target temperature corrected so that the amount of the integral after the Correction becomes smaller or at least grows more slowly than without the correction. This ensures that the Difference between the set temperature curve and the actual Average temperature profile is zero. Then that is also the energy that is introduced into the baked goods equal to the energy generated by the target temperature curve is specified.

The correction of the target temperature can take place in fixed times be carried out. The time intervals can be short versus the total baking time and for example also be 30 seconds. Through the resulting häu Correction of the target temperature becomes excessive Increase of the integral and thus an excessive increase the deviation between the target E to be supplied increases energy and the supplied actual energy counteracted. The Correction of the energy supplied is a short Correction interval promptly carried out on the target energy curve men. This keeps the sequence of the respective back sections get what a positive impact on the Has baking result.

The correction of the target temperature is advantageous performed a baking section. By doing this fewer control processes than the previous one Embodiment necessary. The extra energy Bread in the baked goods nevertheless takes place relatively promptly because after a single baking section instead.  

Preferably, the corrected target temperature after the Passing through the last baking section held so long until the amount of the integral still formed at zero lies. This embodiment ensures that the actual energy supplied with the required target energy also matches if after going through the last baking section still a difference between the Target energy and the actual energy existed.

Furthermore, the correction of the target temperature by Ad a positive or negative correction value be performed. The sign and the amount of the correction turwert depend on the value of the integral. The correction the setpoint temperature can thus be technically simple to lead.

It is advantageous that the amount of the correction value is proportional to determine the amount of the integral. So with small ones Deviations a small correction value and with large Ab a large correction value for control puts. On the one hand, this makes control steps too extreme and thus an overshoot or settling of the control avoided, on the other hand, however, large energy differences zen quickly settled.

In a further embodiment, the amount of the Cor rectification value limited by a maximum value. Thereby it is prevented that with a large integral value the Baked goods burned by extreme temperature correction or one will affect the final baking result exposed temperature.  

The correction values are advantageously in discrete values in front. The control processes can be related to the respective techni adapted to the conditions of the furnace and the heating source become. On a stepless control of the heating source so be dispensed with.

The correction of the target temperature can continue with a Multiplication of the target temperature by a correction factor be made. The value of the correction factor depends on the amount and sign of the integral. The correction the target value can be carried out so easily.

The correction factor preferably has either the value 1, or a value smaller or larger than 1. If the dif reference between target energy and actual energy at zero, see above the correction factor is set to 1. Is the integral non-zero, so the correction factor can be in the way be adjusted that the amount of the integral either gets smaller or at least rises more slowly than without Korrekturaktor. This will correct the differences between target energy and actual energy is easily possible.

The correction factor becomes especially proportional to the Be of the integral. This guarantees on the one hand achieves that large deviations between target energy and Actual energy can be adjusted quickly, on the other becomes an overshoot or a settling of the control avoided by extreme corrections of the target temperature.

In a further embodiment, the amount of the Cor rectification factor by a maximum and a minimum Value limited. These limitations result in extreme temperature corrections  prevents the burning of the Backguts could lead. Due to the limitations au also an overshoot or settling of the system avoided.

Further features and advantages of the invention are described in the following description based on some exemplary Temperature curves clarified. Show it:

Fig. 1 is a schematic representation of a target temperature turverlaufs a typical baking cycle and a resulting actual temperature profile without the use of the inventive method,

Fig. 2 is a schematic representation of a curve of the time-integrated differences between the desired and actual temperature of FIG. 1,

Fig. 3 is a schematic representation of the target temperature curve of FIG. 1 with predetermined and fixed time intervals to the target running Temperaturver added thereto correction values,

FIG. 4 shows a schematic representation of a course of the differences between target and actual temperatures from FIG. 3 integrated over time, FIG.

Fig. 5 is a schematic representation of the predetermined Cor compensation values from Fig. 3,

Fig. 6 is a schematic representation of the target temperature curve of FIG. 1 with predetermined and after the baking section to the added correction values and a schematic representation of the time-integrated differences between setpoint and actual temperature,

Fig. 7 is a schematic representation of the target temperature curve from Fig. 1 with a predetermined correction value added after the end of the baking cycle and a schematic representation of the differences between the target and actual temperatures integrated over time.

Fig. 1 shows schematically a desired temperature gradient T _set and a corresponding actual temperature profile T _is a generic oven. The target temperature curve T _should illustrates a typical baking cycle which consists of Various NEN jaw sections SA ₁ to SA _5, in which different target temperatures T _set are predetermined. After passing through the last baking section BA ₅ , the baking cycle is ended by opening the oven door.

The measured in the baking space of the oven actual temperature T _is showing a characteristic curve. At the beginning of the baking cycle, the dough blanks, which are either at room temperature or cooled or frozen, are shot into the oven. In this first baking section BA ₁ , steam is also introduced into the baking chamber. Furthermore, the door of the oven is open for a certain time during the shooting. Due to these circumstances at the beginning of the baking cycle, the temperature T in the baking chamber drops rapidly. The desired temperature gradient T _should not one be held and will fall below regularly.

A characteristic temperature behavior can also be seen in the further course of the baking cycle. The actual temperatures T _is behave in relation to the desired temperature gradient T _to set heating and cooling sections sluggish. The reasons for this include the air, dough and metal masses involved in the interior of the oven, all of which have their own heat capacity. The actual temperature curve T _is therefore follows the desired temperature gradient T _to a ge know delay shear in the cooling sections due to isolation caused by heat loss of the oven typi manner is lower than in the heating sections. The inertia of the oven also varies, among other things, with the load, since different dough masses in particular participate in the baking process.

As a result of the above deviations of the actual Tem peraturverlaufs T _{is to} the desired temperature gradient T results that the dough pieces regularly less energy is supplied, as by the target temperature curve T was added _to before. For the reasons described above, this difference between the target energy and the actual energy also depends to a large extent on the occupancy of the oven, so that different bac k results are achieved with different occupancy.

The area S between the target temperature profile T _soll and the actual temperature profile T _ist , which is obtained by integrating the difference between the two temperature profiles, can be used as a measure of the energy difference between the actual energy and the actual temperatures T _ist The target energy predetermined by the target temperature profile T _{should be} considered.

In FIG. 2, the integral S is the difference between the desired and the actual temperature plotted over time, ie over the course of the baking process. The aforementioned deviations from the actual temperature T _is from the target temperature T _should be clearly seen here. What is striking is that the surfaces S between the target temperature curve T _set and the actual temperature profile T _is not add up at the end of the baking cycle to zero. In this example, the energy supplied is lower than the energy that _was predetermined by the target temperature profile T target.

In Fig. 3, the schematic desired temperature gradient is T _set of FIG. 1. _To this target temperature curve T correction values KW which are determined with the aid of the inventive process are added. From this he gives the represented new desired temperature gradient T _set, after which the heat source of the oven is controlled. With this new desired temperature gradient T _will result schematically shown actual temperature profile _T.

To determine the correction values KW is the difference between the setpoint temperature T _set and the actual temperature T _is continuously integrated over time and the value of Inte Grail at a given time S rated as follows. If the value of the integral S is zero, the correction value KW is zero. If the value of the integral S is less than zero, a negative correction value KW _is added to the target temperature T set. If the value of the integral S is greater than zero, a positive correction value KW _is added to the target temperature T target.

The amount of the correction value KW can be determined in different ways. In Fig. 3, two constant amounts (5 ° and 10 °) for the correction value KW were set in order to adapt the control processes to the possible control steps of the heating source on the one hand and the baked goods on the other hand not to changes due to extreme temperature changes burn.

With a more finely graduated control of the heating source, however, it is also conceivable to determine the correction values KW directly in proportion to the value of the integral S. Limiting the correction value KW to a maximum value KW _max makes sense in order to avoid destroying the baked goods. The maximum achievable temperature of the oven must always be considered as a limit when determining all correction values KW.

Even after the addition of the correction value KW to the desired temperature T _set is then continue running the difference between the original target temperature T _set and the actual temperature T _is integrated, without deleting the preceding value. The sign and amount of the correction value KW ensure that the value of the integral S becomes smaller in the further course of the baking cycle or at least increases more slowly than without a correction value KW.

This process of determination and the subsequent addition of Correction values KW at fixed times will be until End of baking process continued.  

In FIG. 4 the integral S is the difference between the setpoint temperature T _set and the actual temperature T _is shown over the course of the baking process when applying the inventive method SEN in FIG. 3. In comparison with Fig. 2 it is evident that the differential area between the actual temperature curve T _and the set temperature T _set course disappears at the end of the baking cycle. The energy specified from the original target temperature profile T set _is thus equal to the energy supplied to the baked goods from the actual temperature profile T _ist . The mean values of the energies correspond at the end of the baking process.

The method according to the invention ensures uniformity total baking result regardless of the occupancy of the oven, un depending on fluctuations in the steam supply and independent depending on the degree of maintenance of the door insulation. A special "learning process" of the control method, e.g. B. with a full oven, is not required.

In Fig. 5, the correction values KW over the baking cycle are shown of time. The height of the correction value KW was set to the two values 5 ° and 10 °. A larger number of discrete values than those entered in FIG. 5 can be useful for certain types of furnaces. A value that is directly proportional to the value of the integral S is also conceivable if the control of the heating source supports this.

Fig. 6 again shows the schematic target Temperaturver run _to T in Fig. 1. The differences between the desired temperature profile T _{set and} the actual temperature profile T are integrated. Here, in contrast to FIG. 3, the integral S is only evaluated after the end of each baking section BA ₁ to BA ₅ . For this purpose, a correction value per KW is proportional to the determined value of the integral S and the target temperature T of the next jaw portion _intended added, with the amount of the correction value HC is limited to a maximum value _max KW. This new target temperature T _set is maintained until the amount of the integral S has dropped to zero. Because then the value of the target temperature T _set back _to the old desired temperature T set. The differences occur between the set temperature profile T _set and actual temperature curve _T will continue to integrate continuously.

After completing a baking section, the next Cor rectification value KW calculated. At the end of the target baking cycle additionally at a temperature T that corresponds to the correction value KW as long as baked until the amount of In tegrals S has dropped to zero. Then the backvor The course was broken off by opening the oven.

Fig. 7 shows again the schematic course of the set-Tem temperature T _set of FIG. 1. The differences between the desired temperature profile T _{set and} the actual temperature profile T are integrated. At the end of the set-back cycle after the passage of the jaw portion BA ₅ of the integral S is determined, a correction value proportional to the KW value as a new setpoint temperature T _set is set. The furnace is then operated until the amount of the integral S has dropped to zero. Then the baking process is interrupted by opening the door.

The invention is not limited to the aforementioned exemplary temperature profiles. Essential for the he The only thing is that an oven has a difference Measurement of target and actual temperature is controlled, whereby the difference is integrated in time and from that resulting integral very small at the end of the baking process is.

Claims (13)

1. A method for regulating the heating output of an oven in dependence on a target temperature which can be predetermined in particular for a given baking process with at least one baking section and an actual temperature recorded in the interior of the oven, characterized in that the difference between the target temperature (T _soll) and the actual temperature (T _ist) integrated over the baking time (t) and the set temperature (T _soll) to at least one time during the baking process in dependence on the value of the integral (S) of the difference _(to T) between the target temperature and the actual temperature (T _ist) is corrected over the baking time (t). 2. The method according to claim 1, characterized in that the set temperature (T _soll) is yaws Corridor in such a way that the amount of the integral (S) in the further course of the baking process is less than or increases more slowly than without correction. 3. A method according to any one of claims 1 or 2, as by in that the set temperature (T _soll) at fixed time intervals, in particular every 30 seconds, is corrected. 4. The method according to any one of claims 1 or 2, as is corrected after each baking section by in that the set temperature (T _soll). 5. The method according to any one of the preceding claims, characterized in that the corrected target temperature (T _soll) is maintained for as long-section after the end of the last Backab until the amount of the integral (S) has reached the value zero. 6. The method according to any one of the preceding claims, characterized in that _(to T) for correction of the target temperature, a positive or negative correction value (KW) to the desired temperature (T _soll) is added, with the magnitude and sign of the Cor rekturwerts (KW) are dependent on the value of the integral (S). 7. The method according to any one of the preceding claims, characterized in that the amount of corrective value (KW) proportional to the amount of the value of the Integrals (S) is. 8. The method according to any one of the preceding claims, characterized in that the amount of the correction value (KW) is limited by a maximum value (KW _max ). 9. The method according to any one of the preceding claims, characterized in that the correction value (KW) increases in discrete steps. 10. A method according to any one of claims 1 to 5, characterized in that _(to T) for correcting the target temperature the target temperature (T _soll) is multiplied by ei nem correction factor (KF), wherein the value of the correction factor (KF ) depends on the amount and sign of the integral (S). 11. The method according to claim 10, characterized in that the correction factor (KF) is either 1 assumes, or a value that is larger or smaller than 1.   12. The method according to any one of claims 10 or 11, there characterized by that the amount of corrective door factor (KF) proportional to the amount of the inte grail (S) is. 13. The method according to any one of claims 10 to 12, characterized in that the correction factor (KF) is limited by a maximum value (KF _max ) and a minimum value (KF _min ).