[0001 ] The invention relates to a baking apparatus and a method according to the preambles of the independent claims.

[0002] Baking apparatuses for the industrial production of baked products such as, for example, flat wafers, hollow wafers, waffles, rolled ice cream cones and the like are known and published in different embodiments. Conventional baking apparatuses have, for example, a plurality of baking tongs which can be folded open and closed and is conveyed along a closed circulating path through an oven. In the folded-open state, a dough or a baking mixture is introduced into the baking tongs. Subsequently, the baking tongs are closed and conveyed through a heated baking chamber, so that a baked molded body, in particular a baked product, is baked in the closed baking tongs. Subsequently, the baking tongs are opened, and the molded body can be removed.

[0003] In the industrial production of baked products, efficiency in production is of great importance. In addition to economic efficiency, energy efficiency and resource efficiency in particular are also critical factors. It is thus advantageous if the baking apparatuses are optimized or improved with respect to their durability, with respect to the minimization of the baking waste, but also with respect to energy consumption.

[0004] Conventional baking machines have a heating system optimized to the effect that all baking tongs have substantially the same temperature, so that a constant product quality is achieved - and this even though the individual products are produced in a plurality of baking tongs. For this purpose, heating over a large surface or heated baking chambers are usually provided, which bring about the most uniform possible temperature across all baking tongs located in the baking chamber. In conventional baking systems, the slowness of the heating system is considered to be advantageous, because it compensates for short-term fluctuations in the energy input and in the heating of the baking tongs, and the temperature is substantially kept equal across all baking tongs.

[0005] In practice, however, it has been found that these conventional heating systems can be disadvantageous in certain operating modes. If the baking machine must be stopped, for example, due to an error, some baking tongs are located in the hot baking chamber and some baking tongs in a cooler region. As a result, some baking tongs cool off more than others during the elimination of the fault. If there is now to be a transition back to regulated baking operation, the cooled baking tongs must be heated more intensely than those which were located in the baking chamber. Due to the large-area, slow heating operations, this can be a relatively lengthy process, because the hot baking plates must not be overheated, but the cool baking plates are to be heated up as quickly as possible.

[0006] This example illustrates that, in dynamic operating modes and heating phases of an industrial baking apparatus, the constant, slow heating of a plurality of baking tongs may be disadvantageous.

[0007] There is therefore a conflict of objectives between uniform heating of the baking chamber and efficient heating in dynamic operating phases.

[0008] The object of the invention is then to increase the efficiency of a baking apparatus and to overcome the disadvantages of the prior art or of the baking apparatuses mentioned at the outset.

[0009] The object according to the invention is achieved in particular by the features of the independent patent claims. [0010] Contrary to the prevailing expert opinion, an improvement in efficiency can be achieved by means of a dynamic, locally delimited heating of the baking plate devices. In particular, the energy consumption in the heating phase can thereby be reduced. In addition, the product quality can be improved. A further advantage can be that the component protection is improved by the proposed measures, whereby the service life of the device is extended.

[0011 ] The invention relates in particular to a baking apparatus for producing baked, preferably edible products. A plurality of openable and closable baking plate devices is preferably provided. It is preferably provided that the baking plate devices each have two baking plates and a baking mold for a baking mixture formed between the closed baking plates.

[0012] Baking plate devices within the meaning of the invention can be, for example, baking tongs with an upper plate and a lower plate for producing flat wafer sheets or hollow wafer sheets. Baking plate devices within the meaning of the invention may in some cases also be multi-part devices, as are used, for example, for the production of cast and baked hollow bodies. These multi-part devices comprise, for example, a divided lower plate, in which a cavity is provided, and an upper plate, which comprises a mandrel that is insertable into the cavity.

[0013] The baking plate devices are preferably conveyed in succession along a direction of movement through a baking section. Preferably, a heating arrangement having at least one heating element arranged in the path of the baking section is provided. It is preferably provided that the heating arrangement heats the baking plate devices when they pass through the baking section for baking the baking mixture in the baking mold. The heating arrangement preferably has a control device for controlling by means of openloop control and/or closed-loop control the heating power output to the baking plate devices. It is preferably provided that the heating arrangement individually controls by means of open-loop control or closed-loop control the heating power for each baking plate device, so that the heating power for each baking plate device can be individually set and adjusted.

[0014] Where appropriate, it is provided that the baking plate devices each have a plurality of baking plate regions arranged next to each other or along the baking plates.

[0015] Where appropriate, it is provided that the heating arrangement individually controls by means of open-loop control or closed-loop control the heating power for the baking plate regions of at least one baking plate device or all baking plate devices, so that the heating power for the baking plate regions of the baking plate devices can be individually set and adjusted. Where appropriate, it is provided that the heating element heats the baking plate devices moving past one after the other, in particular individually.

[0016] Where appropriate, it is provided that the heating arrangement has at least one heating element which is arranged in the path of the baking section and in each case heats only one baking plate region of a baking plate device, and in particular not the entire side of the baking plate device facing the heating element. The baking plate regions are thus preferably smaller than the side of the baking plate facing the respective heating element. As a result, selected regions of the baking plate devices can be individually heated.

[0017] Where appropriate, it is provided that the heating arrangement has a plurality of heating elements, which are arranged next to one another or at different positions transversely to the direction of movement.

[0018] Where appropriate, it is provided that these heating elements individually heat baking plate regions arranged next to one another transversely to the direction of movement. [0019] Where appropriate, it is provided that the heating arrangement has a plurality of heating elements, which are arranged in succession along the direction of movement.

[0020] Where appropriate, it is provided that these heating elements individually heat baking plate devices and/or baking plate regions arranged in succession along the direction of movement.

[0021 ] Where appropriate, it is provided that the control device comprises at least one sensor which receives parameters of the baking process, and whose sensor signal is an input variable for the open-loop control or closed-loop control of the heating power carried out by the control device. The control device can be formed at least partially by the machine controller of the baking apparatus.

[0022] Where appropriate, it is provided that the parameters recorded by the sensor are assigned in the control device of the respective baking plate device or the respective baking plate region.

[0023] Where appropriate, it is provided that one or more of the following parameters are recorded:

- temperature of a specific baking plate device,

- temperatures of a plurality of or all baking plate devices,

- temperature of a baking plate region of a specific baking plate device (1 ),

- temperatures of a plurality of or all of the baking plate regions of a baking plate device,

- temperatures of a baking plate region or a plurality of or all baking plate regions of a plurality of or all of the baking plate devices,

- product parameters of baked products, such as residual moisture after the baking or the degree of browning after the baking. [0024] The distribution of the degree of browning or the residual moisture may in some cases be determined in a spatially resolved manner on the products. This occurs, for example, via optical methods in the VIS or NIR region. This simplifies a regulation of the heating power of individual baking plate regions based on the product parameters.

[0025] In particular, the invention relates to a baking apparatus according to the invention comprising an endless conveyor, which conveys the baking plate devices one after the other continuously in succession:

- through a baking mixture application region for introducing a baking mixture into the opened baking plate devices,

- through a closing region for closing and, where appropriate, locking the baking plate devices,

- through a baking region heated by the heating arrangement for baking the baking mixture arranged in the baking plate devices along the baking section,

- through an opening region for opening the baking plate devices,

- and through a removal region for removing the molded bodies baked from the baking mixture.

[0026] Where appropriate, it is provided that the heating element or at least one heating element is an induction heating element for inductive, in particular contactless heating of the baking plate devices and/or the baking plate regions thereof.

[0027] In particular, the invention relates to a method for operating a baking apparatus for producing baked, preferably edible products.

[0028] It is preferably provided that a plurality of openable and closable baking plate devices is conveyed in succession along a direction of movement through a baking section,

- wherein the baking plate devices preferably each have two baking plates and a baking mold for a baking mixture formed between the closed baking plates, - wherein a heating arrangement preferably is provided with at least one heating element arranged in the path of the baking section,

- wherein the heating arrangement heats the baking plate devices when they pass through the baking section for baking the baking mixture in the baking mold,

- wherein preferably a control device of the heating arrangement controls by means of open-loop control and/or closed-loop control the heating power output to the baking plate devices.

[0029] It is preferably provided that the heating arrangement individually controls by means of open-loop control or closed-loop control the heating power for each baking plate device, so that the heating power for each baking plate device can be individually set and adjusted.

[0030] Where appropriate, it is provided that parameters of the baking process are recorded, and preferably that these parameters are input variables for the open-loop control or closed-loop control of the heating power carried out by the control device.

[0031 ] Where appropriate, it is provided that the recorded parameters are assigned to the respective baking plate device or the respective baking plate region.

[0032] It is preferably provided that the baking apparatus is suitable and/or configured for producing wafer products. Where appropriate, it is provided that the baking apparatus is configured for production under overpressure of baked, crispy, brittle wafers from a baking mixture containing 55 to 70% water. In this embodiment, the baking mold is an overpressure baking mold formed by closing and locking the baking plate device. In particular, it is provided that the baking plate devices each comprise steam bars and/or sealing strips. Alternatively, the baking apparatus can also be a baking machine for the industrial production of wafer products which are substantially baked without pressure, such as, for example, sugared wafers or waffles

[0033] It is preferably provided that the baking plate devices are conveyed through the baking section continuously and/or at a constant speed. It is preferably provided that the heating arrangement, in particular the heating elements, are arranged in an unmoved or stationary state. In this case, the baking plate devices move past the heating element or the heating elements. The heating elements may be attached, for example, to the machine frame or to the housing of the baking apparatus. If necessary, the heating elements are adjustably mounted in their position in the baking apparatus, so that, for example, the air gap can be set in the case of induction heating elements. During normal operation, i.e., for example in baking operation, during the heating and cooling phase the heating elements are preferably arranged rigidly.

[0034] The open-loop control and/or closed-loop control of the heating power is preferably carried out in all embodiments by the supply of more or less energy, i.e., electrical energy in electrical or inductive heating elements or fuel energy in the case of gas-operated heating elements.

[0035] The baking apparatus preferably comprises a substantially closed housing. The housing preferably has an elongated shape. The housing can have openings for supplying various working media and for outputting the baked products.

[0036] Where appropriate, a header is provided in which the baking mixture application region, the closing region, the opening region and the removal region are provided. Preferably, the header is separated from the baking chamber by a wall, so that a smaller temperature prevails in the header than in the baking chamber. If necessary, however, this header wall can also be omitted, so that the aforementioned regions are provided within the baking chamber.

[0037] It is preferably provided that the temperature of each individual baking plate device or each individual baking plate region can be individually controlled by means of open-loop control or closed-loop control. In particular, the heating power of the heating elements is controlled by means of open-loop control or closed-loop control individually. Since the baking plate regions can preferably be regions of one and the same baking plate, heat is conducted from one region to the adjoining region. As a result, no completely individual and independent adjustment of the temperatures in these regions can take place. However, the heating power for each of these baking plate regions can be individually adjusted within the scope of the possibilities of the heating arrangement.

[0038] The heating elements are preferably designed such that the heating power can be adjusted sufficiently quickly and dynamically. This can take place, for example, via inductively acting heating elements, the heating power of which can be adapted quickly and flexibly by a simple open-loop power control or closed-loop power control. However, other heating elements can in principle also be used as long as they have a sufficiently small heating region and a sufficiently dynamic response behavior for the individual heating of the baking plate devices or the baking plate regions thereof.

[0039] Preferably, at least one sensor is provided, which records parameters of the baking process, wherein the sensor signal is used to control by means of open-loop control or closed-loop control the heating power. The sensor can be, for example, a pyrometric temperature sensor which carries out temperature measurements on the baking plate surfaces, i.e. , in particular on the surfaces on the baking mold side or on the back sides of the baking plates or of the baking plate devices. Preferably, the sensor or a plurality of sensors can record the temperatures of the individual baking plate regions and transmit a measurement signal for controlling by means of open-loop control and/or closed-loop control the heating power of the heating elements to the control device. Preferably, the measurement is carried out on the heated back sides or at positions which can also be measured pyrometrically after closure of the baking plate devices. A measurement of the temperature on the baking mold side would be possible, for example, between the removal of the baked product and the infusion of the dough or between the removal of the wafer sheet and closing of the baking mold. A measurement of the temperature on the baking mold side would in some cases be possible in the removal region, in the dough application region and therebetween or in the removal region, in the closing region and therebetween.

[0040] Where appropriate, a sensor can also be provided, which records parameters of the produced product or products. Such a sensor can, for example, be an optical sensor which records the degree of browning of the baked product during removal. The sensor can, for example, also be or comprise a measuring device for determining the residual moisture or the weight of the products.

[0041 ] In all embodiments, it is preferably provided that the parameters recorded by the sensor or parameters calculated therefrom are assigned to or associated with the individual baking plate devices and/or the baking plate regions. In particular, this assignment allows the individual closed-loop or open-loop control of the heating power for each baking plate device or each baking plate region.

[0042] Where appropriate, it is provided that the baking section extends along an upper transport plane. Where appropriate, it is provided that the baking section runs from an upper transport plane over a deflection point to a lower transport plane. [0043] Where appropriate, it is provided that the heating elements are arranged above the baking section. Where appropriate, it is provided that the heating elements are provided below the baking section. Where appropriate, it is provided that the heating elements are provided on both sides, in particular above and below the baking section. Where appropriate, it is provided that heating elements are provided along the upper and lower transport planes, wherein these heating elements are arrangeable above, below or on both sides of the transport planes. In particular, it is provided that each of the two plates of the baking plate devices are heated by the heating arrangement in the path of the baking section.

[0044] In particular, the following advantages can be achieved by the described baking apparatus and the described method:

- Time-optimized reaching of the target temperature without overshooting in the heating phase.

- Temperature control over trajectories, so that the temperatures of upper and lower baking plates are kept close together to avoid irreversible mechanical deformations.

- Temperature control over all baking plates with as little temperature deviation as possible.

- In normal baking operation, a rapid compensation of temperature differences between the baking plates can be achieved in order to ensure as constant a baking process as possible.

- It is possible to respond particularly quickly to the starting and stopping of the infusion of the baking mixture in the application region.

- In addition, the amount of infusion and, for example, also the water content of the baking mixture can be taken into account in order to achieve short adjustment times and small temperature deviations to the target temperature. -A different energy requirement, caused by different mechanical settings, such as for example different wafer sheet thicknesses, can also be easily compensated by the baking apparatus and the method. - It is also possible to provide different baking molds in the baking apparatus, because individual heating can be carried out by the baking apparatus according to the invention or the method according to the invention due to different engravings, amounts of dough, dough recipes etc.

- In addition, a direct regulation of a product quality variable such as, for example, degree of browning, residual moisture or weight is preferably made possible.

[0045] The baking apparatus or the method can advantageously carry out an efficient heating phase of the baking apparatus. In this way, specifically those baking plate devices or baking plate regions can be individually heated with an adapted heating power in order to achieve the desired temperature as quickly as possible, but without heating those baking plates or regions which already have the target temperature. In particular, the individual heating of baking plate regions during the heating phase also reduces thermal stresses within a baking plate, but also thermal stresses of different components of a baking plate device. Preferably, components of the baking plate devices such as, for example, a hinge, a closure, a frame, sensors, etc. can be individually heated less in order to protect these components or to keep them at a desired temperature.

[0046] Preferably, the temperature differences between the upper plate and the lower plate of a baking plate device can also be reduced or kept as small as possible. This can be done on the one hand by the individual open-loop control and/or closed-loop control of the heating power. In addition, heating elements can also be provided along the baking section on both sides of the baking plate devices, that is to say in the same region above and below, in order to be able to heat the upper plate and the lower plate of a baking plate device at the same time.

[0047] In the baking operation, for example, the baking plate region can be heated with a higher heating power, in which the dough infusion takes place. The dough infusion cools off the baking plates, whereby a higher heating power is advantageous in this region. This can be done by the individual openloop control or closed-loop control, without less cooled regions being overheated by the heating elements.

[0048] In addition, individual heating of regions or baking plate devices can also take place when individual baking plates are conveyed through the baking machine without dough infusion. As a result, the output of the baking apparatus can be varied in 1 -baking-plate-device increments, that is to say substantially steplessly. In particular, the number of baked products produced per time can be varied in that not all, but rather any number of baking plate devices, are provided with or loaded with a baking mixture. The control device then adjusts the required heating power for each baking plate device.

[0049] It is also possible to use different baking plate devices for producing differently shaped products via the baking apparatus and the method, because the heating power for each baking plate device can be adapted individually. Thus, for example, baking molds with a larger baking mixture volume generally require a greater heating power than baking molds with a smaller volume.

[0050] Moreover, each baking plate device or each baking plate region can in some cases be heated with an individual temporal temperature profile.

[0051 ] According to a preferred embodiment, for each baking plate or for each baking plate device during the baking process, a specific temperature profile, i.e. , an individually adjustable temporal temperature profile, can be traversed in order to influence product properties such as the brittleness or other consistency parameters in a targeted manner. For example, a slow heating takes place in the path of the baking section if the first heating element outputs a smaller heating power than the subsequent heating elements when such heating elements are connected one behind the other in series. Alternatively, rapid heating can take place in that the first or a front heating element already outputs a high heating power to the baking plate device.

[0052] In the heating and/or cooling phase, a temperature control can take place via trajectories, so that the temperatures of upper and lower baking plates of a baking plate device are substantially the same during the change in temperature, in order to avoid deformations. In addition, a temperature control over all baking plates with the smallest possible temperature deviation can be carried out with one another, where appropriate.

[0053] Where appropriate, the baking apparatus and the method can also be used for monitoring the baking process. For model-based control, it is in some cases necessary to carry out state estimations, such as the estimation of the degree of emissions of baking plate rear sides. With these estimations and compared to the set degree of emissions in the temperature sensor, fluctuations in the surface properties of the baking plates can be detected - for example due to soiling, corrosion or manual change - and can be used for a diagnosis.

[0054] It is preferably provided that individual baking plate variables such as, for example, baking plate temperatures or temperatures of the baking plate regions are controlled by means of open-loop control or closed-loop control. Where appropriate, it is provided that the sensor or sensors are designed such that corresponding variables, such as the temperatures, can be calculated from their measured values.

[0055] It is preferably provided that the heating elements or the heating element are configured such that the baking plates of the baking plate devices or of the baking plate regions thereof can be supplied with different or selectable heating powers. In particular, the heating region of the heating element should be small enough and respond sufficiently quickly to changes in the target variable. [0056] It is preferably provided in all embodiments that the heating region of a heating element is smaller than a baking plate, in particular smaller than the side of a baking plate that faces the heating element. It is preferably provided that the heating region of a heating element is smaller than the extension of the baking plate device, so that a baking plate region can be individually heated.

[0057] It is preferably provided in all embodiments that the described method is carried out on the described baking apparatus. It is preferably provided in all embodiments that the described baking apparatus is configured to carry out the described method.

[0058] It is preferably provided that the baking plate devices are conveyed along a direction of movement through a baking section one after the other, in particular in succession. A heating arrangement for heating the baking plate devices is provided along the baking section, said heating arrangement comprising a plurality of heating elements in a preferred embodiment.

[0059] If the heating elements are arranged one behind the other along the direction of movement of the baking plate devices, the baking plate devices are heated in succession by the heating elements. If a baking plate device is considered, this comes into the heating region of a heating element and, at a later point in time or subsequently in the further path of the movement of the baking plate device, into the heating region of a further heating element.

[0060] Depending on the distance between the baking plate devices and the heating elements, it can be provided here that, while the one baking plate device is heated by the further heating element, the preceding heating element heats another baking plate device. [0061 ] It is preferably provided that the individual heating elements of the heating arrangement are arranged in a manner distributed over the entire baking section. Where appropriate, the heating elements are arranged in a manner distributed regularly or irregularly along the baking section. Preferably, the heating power of those heating elements which are arranged at the start of the baking section is greater than the heating power of the subsequent heating elements.

[0062] In order now to enable individual heating of the baking plate devices, the individual baking plate devices are preferably identified by the control device. This identification can be accomplished, for example, by a sensor which records an individual signal of a baking plate and thereby identifies the baking plate. Alternatively, this can also take place in that the position of the individual devices can be determined or calculated via a signal of the movement speed of the baking plate devices. If a baking plate device now moves along the heating section, this baking plate device is individually heated by the heating elements and the heating power of the individual heating elements is specifically adapted for this baking plate device. Of course, this adjustment takes place only when an adjustment is necessary. The heating power of the heating elements for the other baking plate devices can also be individually adapted.

[0063] Additionally or alternatively, it is possible according to the present device and the method that a plurality of heating elements is provided transversely to the direction of movement of the baking plate devices. These are designed and/or suitable for individually heating baking plate regions of the baking plate devices. For example, a lateral strip of a baking plate device can be heated with a heating power other than a central strip. Where appropriate, only one lateral strip or only one central strip can be heated.

[0064] Where appropriate, it can be provided that a plurality of baking plate regions is also defined respectively along the baking plate devices. Thus, for example, the front edge of a baking plate or a baking plate device, viewed along the direction of movement, can be heated with a different heating power than the central region or the rear edge of the baking plate device as viewed along the direction of movement. It is preferably provided that the heating power for the baking plate regions of all the baking plate devices can be individually controlled by means of open-loop control or closed-loop control. The baking plate regions are in particular regions arranged adjacent to one another along the back surfaces of the baking plate devices or the baking plates.

[0065] Preferably, the baking plate regions are identified and individually heated. The individual heating can also be accomplished by the position of the respective baking plate regions along the baking section being determined via the speed of the baking plate devices along the direction of movement and via a time signal. Individual heating of these baking plate regions can then be accomplished via the control device.

[0066] The heating elements are thus controlled by means of open-loop control or closed-loop control over time in such a way that the heating power is adjusted or else kept the same. This temporal open-loop control and/or closed- loop control of the heating power of the individual heating elements is synchronized in particular with the movement of the baking plate devices, so that the heating elements can selectively and individually heat the baking plate devices or the baking plate regions.

[0067] The selection of the heating power can take place by a simple individual control for each baking plate device or for each baking plate region. For example, an operator can carry out an individual setting for each baking plate device or each baking plate region. However, a sensor is preferably provided, which records a parameter that enables automatic open-loop control and/or closed-loop control by the control device. In particular in dynamic heating phases, such as, for example, in the heating phase, in the cooling phase or during the start of the baking mixture infusion, it is advantageous to configure sensor data for regulating the heating power for each baking plate device or for each baking plate region.

[0068] It is preferably provided for a mathematical model to be stored in the control device for regulation, which model actively compensates for the inhomogeneity by means of state regulation and, in particular, can easily be transmitted to different types of oven or similar oven types.

[0069] Where appropriate, it is provided that the underlying mathematical model can be converted into a linear time-invariant (LTI) form by linear approximation, sampling and/or state transformation. Where appropriate, a combination of a Kalman filter with an LQR controller is used.

[0070] In order to improve the regulation of the baking apparatus, a model which corresponds to a simplified mathematical representation of the baking apparatus is preferably stored. In particular, the heat flows or the thermal balances of the individual baking plate devices or of the individual baking plates are taken into account in this model, i.e. , for example, the amount of heat introduced through the heating arrangement, the heat quantity absorbed by the baking mixture, heat losses by radiation, heat conduction to adjacent baking plate regions or baking plate devices, etc. The model can be adjusted or adapted by sensor data of a sensor.

[0071 ] It is preferably provided in all embodiments that the heating power of the at least one heating element or of all heating elements is controlled online. In particular, a plurality of heating elements is provided, which elements are each controlled independently of one another.

[0072] Preferably, the or each baking plate or baking plate device comprises a plurality of baking plate regions, which regions are accommodated next to one another or adjacent to one another on the baking plate. In particular, baking plate regions are accommodated along the extension of the baking plate devices. These regions may be arranged, for example, in a manner distributed over the entire outer surface of the respective baking plate device and, in addition to the back surfaces of the baking plates, also accommodated on further components of the baking plate devices, for example a hinge, a frame part, a closure or similar components.

[0073] The baking plate regions are regions of the baking plate devices, which can be individually heated by the heating elements. Where appropriate, the baking plate regions overlap one another. If necessary, they are arranged next to each other. Where appropriate, the baking plate regions are arranged at a distance from one another.

[0074] Preferably, the baking plate regions are accommodated on those sides of the baking plate devices which face the heating elements.

[0075] It is preferably provided in all embodiments that the baking plate regions extend only over a part of the surface of the baking plate devices that faces the heating elements. For example, it is in each case a part of the back surface of one of the baking plates of a baking plate device. In all embodiments, it is preferably provided that the baking plate devices each have at least two sides. These sides are preferably the back surfaces of the two baking plates. A plurality of baking plate regions, which regions can be individually heated, is preferably accommodated on each of these sides.

[0076] In all embodiments, it is preferably provided that more than two baking plate regions are provided on a baking plate device. In particular, four or more baking plate regions are provided, wherein at least two baking plate regions are preferably accommodated on each side.

[0077] For example, one to four baking plate regions are defined along the direction of movement of the baking plates. For example, one to nine baking plate regions are defined transversely to the direction of movement of the baking plates. For example, a baking plate or a side of the baking plate device comprises between one and 36 baking plate regions and a baking plate device between one and 72 baking plate regions.

The temperature of the baking plate region can be illustrated or determined using the method of weighted residuals, for example finite-volume methods or polynomial approaches.

[0078] Where appropriate, a reference temperature measurement is made. The measuring device for the reference temperature measurement can, for example, be a spring-loaded metal sheet with a curved front edge, on which a thermocouple is fixed and which is mounted on a pivotable holder. This device can be fastened, for example, in front of the application region or in the application region. In particular, this device can be configured for the measurement on the upper baking plate. A second, identical or similar device can be mounted for the measurement on the lower baking plate. The springloaded embodiment is advantageous due to possible steaming or baking strips, which the sheet metal has to overcome. The pivotability of the device is advantageous in order to counteract abrasion of the metal sheet when no reference temperature measurement takes place during the baking process

[0079] Where appropriate, a degree of emissions correction takes place. By comparing model calculations to the measurement data, the degree of emissions of each individual baking plate or of each baking plate region can be monitored and corrected if necessary. For example, the emission of the thermal radiation of a baking plate device can change due to soiling or corrosion. The measurement data can be recorded by a temperature sensor and the calculation can be performed by the control unit. These data can also be used for predictive maintenance in order to reduce downtimes.

[0080] Where appropriate, a power measurement of the heating elements or of the heating element is carried out. If, according to a preferred embodiment, inductors are used as heating elements, they are arranged at a certain distance from the baking plate rear sides in order to set or keep the necessary air gap. This corresponds to a mechanical setting. The mechanical setting simplifies, for example, the commissioning or the troubleshooting. In addition, readjustment by control via current measurement is possible. The power measurement can also be used for the state estimation.

[0081 ] According to a preferred embodiment of the baking apparatus, the discrete baking plates or baking plate devices move past the heating elements with locally concentrated heat input and are heated thereby. The heating elements, preferably inductors, can be supplied with power by drive devices, for example of the drive electronics of the inductors. These drive devices in turn receive one or more control variables, for example the percentage heating power, from one or more control devices. The drive electronics and the control devices can be parts of the control device or, if appropriate, these components are parts of the inductors.

[0082] Sensors are preferably provided which detect measured variables, wherein these measured variables are assigned to the baking plate devices or the baking plate regions thereof. An algorithm in the control device calculates therefrom and in some cases from other known variables - such as dough quantity, target temperature, etc. - the time path of the manipulated variables which are necessary in order to achieve the desired result such as, for example, target temperature, target browning.

[0083] Depending on the requirements of the product, the heating elements can be arranged at a local location or in a manner distributed in the oven. For example, a plurality of zones, in particular three zones, can be provided transversely to the direction of movement of the baking plate device. In particular when using a cascade control with the temperature as the internal control variable, baking plate individual target temperatures are predefined by an outer control loop. The controlled variable of the outer control loop can be, for example, a product property such as the residual moisture or the degree of browning of the product. These measured values or measurement signals are also preferably recorded for each individual baking plate and assigned to a baking plate device. In addition to the temperature measurement, the degree of browning measurement of the product is in some cases a relevant indicator for the regulation, for example whether individual baking plate regions are to be subjected to additional thermal energy. The degree of browning can be directed, for example, to specific zones on the product, wherein a specific degree of browning, depending on the product type, should not be undershot and/or exceeded.

[0084] Where appropriate, it is provided that the dough enthalphy is taken into account in the open-loop control or closed-loop control of the heating power. The dough enthalphy, depending on the amount of dough, can contribute to a targeted heat input into the baking plate. For this purpose, it can be provided that different recipes of baking mixtures are or will be stored on the control device. In particular, the water content has an influence on the enthalpy of the dough. The regulation can then take into account the dough enthalphy on the basis of the stored ingredients and take into account the necessary energy as an interference variable. In addition, a measured amount of dough can be used instead of the nominal value to determine the required energy, in order to counteract temperature differences between baking plates that are caused thereby.

[0085] Where appropriate, it is provided that the reference temperature measurement does not take place constantly, but only during the cooling phase. A correction factor can thus be assigned or calculated per measured baking plate region. First, the temperature can be measured by means of the sensor used for regulation and at the same time also with a pivotable thermocouple. Subsequently, a simple correlation can determine a correction factor between these two measurement data. If the reference measurement is carried out on the baking surface instead of on the baking plate rear side, the calculated correction factor is in some cases a measure of the conversion of the intermediate variable (baking plate rear side temperature) into the relevant variable (temperature at the baking surface).

[0086] Where appropriate, it is provided that the power and thus the direct energy input are determined by current measurement on an inductive heating element, in some cases in combination with a voltage measurement on the drive electronics. If necessary, the current measurement is used when setting the air gaps between the inductors and the surface to be heated.

Where appropriate, it is provided that, instead of a state regulation, a modelbased design and a conversion is performed as FIR/IIR filters or other state space representations.

[0087] Where appropriate, heating elements with different extensions or heating regions are provided. For example, heating elements are provided with a short extension in the direction of movement of the baking plate devices with a greater extension transversely thereto and/or heating elements are provided with a larger extension in the direction of movement of the baking plate devices with a smaller extension transversely thereto. The heating elements with a larger extension in the direction of movement can be provided for example for heating all the baking plates or for heating strip-shaped baking plate regions running in the direction of movement. The elements with short extension in the direction of movement can be provided primarily for individual heating of individual baking plates or for heating transversely extending strip-shaped baking plate regions. The smaller the heating elements or the heating regions thereof, the smaller the individually heatable baking plate regions can be selected.

Where appropriate, it is provided that the heating power for each baking plate device or for each baking plate region is controlled by means of open-loop control and not controlled by means of closed-loop control.

[0088] The invention will be further described below with reference to figures. [0089] Fig. 1 shows a schematic sectional view of a possible embodiment of a baking apparatus, in particular in a side view.

[0090] Fig. 2 shows a schematic sectional view of components of a baking apparatus, in particular in a plan view.

[0091 ] Fig. 3 shows a schematic oblique view of a possible embodiment of a baking plate device.

[0092] Fig. 4a and 4b show schematic block diagrams of open-loop controls or closed-loop controls of the control device.

[0093] Unless stated otherwise, the reference signs of the figures correspond to the following components: Baking plate device 1 , upper baking plate 2, lower baking plate 3, baking section 4, heating element 5, control device 6, baking plate region 7, sensor 8, endless conveyor 9, baking mixture application region 10, closing region 11 , baking region 12, opening region 13, removal region 14, heating arrangement 15, direction of movement 16, exogenous inputs and/or interference variables 17, individual target variables (e.g., temperature) of the baking plate devices 18, control algorithm 19, control variables 20, controlled system of the baking apparatus 21 , product stream 22, measured variable(s) 23, product property controller 24, temperature controller 25, product property 26, temperature or heating power 27.

[0094] Fig. 1 shows a schematic side view of a baking apparatus. The baking apparatus comprises a plurality of baking plate devices 1 , but not all baking plate devices 1 are shown, only some of them. Preferably, the baking plate devices 1 are provided one after the other on an endless conveyor 9. The endless conveyor 9 is, for example, a chain conveyor or a belt conveyor which conveys the baking plate devices 1 through the baking apparatus. In particular, the baking plate devices 1 are moved continuously through the baking apparatus.

[0095] In the present embodiment, the baking plate devices 1 each comprise an upper baking plate 2 and a lower baking plate 3. The baking plates 2, 3 can, for example, be connected to one another in a hinge-like manner in order, as in this embodiment, to form baking tongs. The baking plate device 1 is opened in an opening region 13. In a removal region 14, the baked products or molded bodies are removed from the baking plate devices 1 and conveyed out of the baking apparatus. The opened baking plate devices 1 are loaded with a baking mixture in a baking mixture application region 10. In particular, the baking mixture is applied to one or both baking plates 2, 3. This application of the baking mixture or the dough can take place via a conventional dough application device, such as, for example, by means of a dough infuser.

[0096] Subsequently, the baking plate devices 1 are closed in a closing region 11 and, depending on the type of the baking machine, locked. The locking makes it possible in combination with sealing or steam bars that the two baking plates 2, 3 together form an overpressure baking mold.

[0097] The closed baking plate device 1 is subsequently heated along a baking section 4 for the purpose of baking the products. The baking section 4 extends through a baking region 12 of the baking apparatus. The baking region 12 is, for example, the baking chamber of a baking apparatus which is heated by a heating arrangement 15. In particular, the heating arrangement 15 is suitable and/or configured to heat the baking plate devices 1 or the baking plates 2, 3 thereof.

[0098] The baking chamber, i.e., in particular the baking region 12, can be separated from the regions 10, 11 , 13 and 14 by means of a header wall, wherein the endless conveyor 9 can extend through openings of this head wall with the baking plate devices 1. Alternatively, this header wall can be omitted, so that an increased temperature is also provided in the aforementioned regions.

[0099] The heating arrangement 15 comprises a plurality of heating elements 5. In the present embodiment, a heating element 5 is provided in each case above and below the baking section 4 or the baking plate devices 1 located in the baking section 4. As a result, the upper baking plate 2 and the lower baking plate 3 of the individual baking plate devices 1 are respectively heated along the baking section 4.

[0100] As also in the present embodiment of the baking apparatus, it is customary that the baking section 4 extends along an upper transport plane up to a deflection region and further along a lower transport plane. During the transition from the upper transport plane to the lower transport plane, the baking plate devices 1 are preferably pivoted 180°. If heating elements 5 are always arranged only above or always only below the baking section 4 in the path of the upper and lower transport planes, the upper baking plate 2 and the lower baking plate 3 are nevertheless heated in such an embodiment, because the baking plate devices 1 are turned over at the rear deflection point. The baking plates 2, 3 are thus heated in succession along the baking section 4. In the present example of the baking apparatus, however, heating elements 5 are provided above and below the baking section 4, and this along the upper transport plane and/or along the lower transport plane. The baking plates 2, 3 of a baking plate device 1 are thereby heated simultaneously by two heating elements 5.

[0101 ] The heating elements 5 are preferably designed such that they each heat only one baking plate device 1 or only one baking plate 2, 3. According to a preferred embodiment, the heating elements 5 may be designed such that they only heat one region of the baking plate devices 1. For these functionalities, it is advantageous if the heating elements 5 have a relatively small heating region. In particular, the effect of a heating element 5 does not extend over a plurality of baking plate devices 1 , but instead only on that baking plate device 1 , which is in the region of the immediate influence of the respective heating element 5.

[0102] A plurality of heating elements 5 can be arranged in succession along the direction of movement 16 of the baking plate devices 1 on the baking section 4. If a baking plate device 1 which is moved by the endless conveyor 9 along the baking section 4 and along the direction of movement 16 is considered, this baking plate device 1 is thereby heated successively by a plurality of heating elements 5.

[0103] The heating power of these heating elements 5 can be adjusted or controlled individually. For this purpose, a control device 6 is provided. In addition, the control device 6 can comprise at least one sensor 8. In the present embodiment, a plurality of sensors 8 is provided. One of the sensors 8 is provided in a region of the baking apparatus in which the baking plate devices 1 are opened. As a result, the sensor 8, for example a temperature sensor, in particular a pyrometric sensor, can record temperatures on the baking mold side of the baking plates 2, 3. In particular, such measurement signals or sensor data may be recorded for both baking plates 2, 3 of each baking plate device 1 . The recorded measurement signals are preferably assigned to the respective baking plate devices 1 or baking plates 2, 3 in the control device 6. This helps in the individual closed-loop or open-loop control of the heating power for each baking plate device 1 . Alternatively, the sensor 8 can also measure temperatures of the baking mold back sides or the outer surface of the closed baking plate devices 1. In some cases, two sensors 8 may be provided, which measure the temperatures on opposite sides of the baking plate devices 1 . In all embodiments, it can be provided that the sensor 8 or the sensors 8 measure the temperatures of the baking plate regions 7 and/or that temperatures are assigned to the baking plate regions 7. [0104] In the present embodiment, a sensor 8 is also provided in the removal region 14. In particular, the sensor 8 is provided in a region in which the baked products or molded bodies are conveyed out of the baking apparatus. This sensor 8 can, for example, be an optical sensor 8 for detecting the browning of the baked product. Alternatively, the baked products or the baked molded bodies may also be weighed or the residual moisture can be determined. These sensor data may be assigned to a specific baking plate device 1 in the control device 6. This also simplifies the individual closed-loop or open-loop control of the heating elements 5 for each baking plate device 1. If, for example, the baked molded bodies of a specific baking plate device 1 have a heavier degree of browning or a lower residual moisture than the baked molded bodies of the other baking plate devices 1 , the heating power can be reduced for just this baking plate device 1 . Likewise, the heating power for a specific baking plate device 1 can be increased if the residual moisture of the molded bodies baked in this baking plate device 1 is too high.

[0105] Fig. 2 shows a schematic sectional illustration or plan view of significant components of a baking apparatus, in particular of the baking apparatus from Fig. 2. The view schematically shows how a plurality of baking plate devices 1 moves along the direction of movement 16 through the baking section 4. A plurality of heating elements 5 is provided above the baking section 4. In the present embodiment, a plurality of heating elements 5 is provided transversely to the direction of movement 16 of the baking plate devices 1. In particular, three heating elements 5 are arranged next to one another in the illustration. While at least one of the heating elements 5 is configured to heat the baking plate devices 1 in the central region based on its positioning, the external heating elements 5 are intended to heat the edge region of the baking plate devices 1 . This can provide advantages, for example, when the baking mixture is applied centrally to the opened baking plate devices 1 . In particular, the central region of the baking plate device 1 is cooled by the dough enthalphy. More intense heating of the central region compared to the outer region of the baking plate devices results in an efficient heating, because the baking plates 2, 3 can be brought to the optimum baking temperature without having to heat the edge region, in particular mechanical devices such as a hinge or a lock, above the optimal temperature. This has a positive effect on component protection, for example, because bearings or other mechanical components are stressed less intensely by the temperature.

[0106] In the present embodiment of Fig. 2, a plurality of heating elements 5 is provided one after the other along the direction of movement 16, so that the baking plate devices 1 can be heated in order by a plurality of heating elements 5. In addition, however, a plurality of heating elements 5 is also arranged next to one another transversely to the direction of movement 16 in this embodiment. A plurality of heating elements 5 may also be arranged next to one another transversely to the direction of movement 16 underneath the baking section. An arrangement of Fig. 2 can also be provided, for example, in Fig. 1. In principle, each configuration of the heating elements 5 can be selected, which enables the baking plate devices 1 to be heated individually or in regions corresponding to the present invention.

[0107] Fig. 3 shows a schematic oblique view of an embodiment of a baking plate device 1. The baking plate device 1 comprises an upper baking plate 2 and a lower baking plate 3. In the present embodiment, the baking plates 2, 3 are each held by a frame. In principle, however, such a frame can also be omitted, whereby the baking plates 2, 3 are substantially self-supporting. The baking plates 2, 3 are connected to one another in a hinge-like manner, as a result of which baking tongs are formed. In principle, the baking plate devices 1 can also be conventional baking plate devices of conventional generic baking apparatuses.

[0108] A plurality of baking plate regions 7 is defined on the baking plate devices 1. These baking plate regions 7 are shown schematically in the present illustration by dashed lines. By arranging a plurality of heating elements 5 which are limited in their heating region, the individual baking plate regions 7 can be individually heated. Although the baking plate regions 7 are usually parts of one and the same body of a baking plate or the baking plate device 1 , so that a certain heat conduction is unavoidable, the heating of the baking plate regions 7 is nevertheless to be carried out individually.

[0109] For example, in the case of a baking apparatus for the baking plate device 1 of Fig. 3, six heating elements 5 can be arranged next to one another, viewed transversely to the direction of movement 16, and each of which is suitable for carrying out strip-shaped heating of the baking plate device 1 or of one side of the baking plate device 1 . By selectively changing the heating power depending on the position of the baking plate device, the heating power of the baking plate regions 7 arranged along the direction of movement 16 can also be set. Thus, for example, initially the heating power of a heating element 5 can be reduced, in order to heat the front edge region less. If the baking plate device 1 moves further, the heating power of the heating element 5 can be increased in order to heat the central region of the baking plate device 1 more intensely. Subsequently, the heating power can be reduced again in order to heat the opposite edge region of the baking plate device 1 to a lesser degree. By means of such an open-loop control and/or closed-loop control of the heating power of the heating elements 5, the central region of the baking plate device 1 can be heated more intensely than its edge region, for example. Likewise, the outer heating elements 5, viewed transversely to the direction of movement 16, can be operated with less heating power than the centrally arranged heating elements 5, so that a lower heating takes place in the region of the hinge or in the region of the locking and these components can be protected. Such a temperature profile can preferably be individually adjusted for each baking plate device.

[0110] It is advantageous if the heating elements 5 are designed as inductive heating elements 5, which inductively heat the baking plates 2, 3. For this purpose, it is advantageous if the baking plates 2, 3, as shown in Fig. 3, have substantially smooth or optimally molded back surfaces, so that the air gap between the inductor and the baking plate 2, 3 to be heated can be selected to be constant or accurate. In principle, a change in the air gap can also be taken into account by the temporal open-loop control or closed-loop control of the heating power of the heating elements 5.

[0111 ] The signal flows and dependencies in the automation system or the control device 6 are in the form of block diagrams in Figure 4a and Fig. 4b. In particular, these elements comprise the following elements: exogenous inputs and/or interference variables 17, individual target variables (e.g., temperature) of the baking plate devices 18, control algorithm 19, control variables 20, controlled system of the baking apparatus 21 , product stream 22, measured variable(s) 23, product property controller 24, temperature controller 25, product property 26, temperature or heating power 27.

[0112] The individual target variables 18 per baking plate 2, 3 or baking plate device 1 can relate, for example, to the product quality such as browning, residual moisture or the baking plate temperature. In practice, these target variables 18 can usually be selected identically or similarly for all baking plates 2, 3 or baking plate devices 1 , so that uniform products are baked. If, for example, no measured variables 23 are used for calculating the manipulated variables 20, this is an open-loop control, otherwise a closed-loop control.

[0113] The control device 6 makes it possible to individually adjust the heating power and thus the energy introduced via a circulation into individual baking plates 2, 3 and/or baking plate devices 1 . By the unambiguous assignment of the measured variables 23 to the baking plates 2, 3 or baking plate devices 1 , it is possible with a suitable open-loop control or closed-loop control strategy to avoid quality inhomogeneities of the products. In addition, the inhomogeneities caused by disturbances can be actively regulated.

[0114] Building on suitable heating elements 5, a control concept is in some cases used, which selects the manipulated variables 20 on the basis of user inputs and measurements such that the deviation of the controlled variable from the individual target value 18 is minimal for each baking plate 2, 3. For the usual case that all the setpoint values 18 are selected to be the same, this means the greatest possible homogeneity of, for example, the baking plate temperatures or a property, such as the browning of the products.

[0115] As shown in Fig. 4a, the selected model-based open-loop control or closed-loop control strategy 19 allows exogenous inputs 17 (e.g., the amount of dough infusion) and known interference variables 17 to be taken into account directly. As a result, it is possible to compensate for potentially negative influences on the product quality or homogeneity before they become visible in the measured variables 23. Individual measurements per baking plate are advantageous or necessary for a control individualized for each baking plate.

[0116] A cascaded control, as depicted in Fig. 4b, can be used to control, in a manner individualized for each baking plate, a product property, such as the degree of browning or residual moisture.

[0117] In this case, the individual setpoint temperature 18 of each baking plate 2, 3 or baking plate device 1 is adapted by an overlapped controller, in order to ensure the desired product quality on the corresponding baking plate device 1.

[0118] The feedback variables of the superimposed controller 24 are then, for example, measured degrees of browning or residual humidities and associated baking plate numbers, while its manipulated variables 20 are preferably the individual target temperatures of all the baking plate devices or the baking plate regions thereof. The subordinate temperature controller 25 subsequently provides the manipulated variables 20 of the heating elements 5 such that the deviation of the baking plate temperatures from their individual target values 18 becomes minimal.