Abstract:
A device for producing baked products, in particular edible crisp wafers or soft waffles, contains at least one baking plate, the baking surface of which can be heated to a baking temperature. The baking plate has a sensor device for detecting the temperature of the baking plate and/or a pressure acting on the baking surface of the baking plate during the baking process.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a divisional of patent application Ser. No. 14/116,443, filed on Nov. 8, 2013, which was a continuation, under 35 U.S.C. §120, of international application No. PCT/EP2012/058204, filed May 4, 2012, which designated the United States; this application also claims the priority, under 35 U.S.C. §119, of Austrian patent application No. AT A660/2011, filed on May 10, 2011; the prior applications are herewith incorporated by reference in their entirety. 
     
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
       [0002]    The invention relates to an apparatus for producing baked products, in particular edible crispy wafers or soft waffles, where at least one baking plate, preferably moved through the baking chamber during baking, is provided, whose baking surface can be heated to baking temperature. 
         [0003]    Such apparatuses are in particular wafer baking ovens. Wafer baking ovens having circulating baking tongs have been known for a long time for the industrial production of wafers of any kind. Furthermore, it is also already known to measure and regulate the oven temperature in order to achieve a good baking process. However, the temperature measurements at the present time are always made only indirectly by infrared heat sensors which are disposed in the oven chamber and measure the temperature, for example, on the rear side of the baking plate. A disadvantage here is the great inertia of the system and this temperature measurement gives no information on the temperature profile during the baking process in the plate and certainly not at the baking surface. 
         [0004]    The measurement of the pressure which occurs in the closed baking tongs has so far not been made at all in industrial baking processes and has not been used to control the baking process. This applies particularly to baking tongs which are guided through a baking chamber of the oven, where cabling is not possible as in stationary baking ovens. 
         [0005]    The baking process can be varied or disturbed by many factors, resulting in defective baking processes and increased wastage. For example, the dough composition can vary in regard to water content or flour quality or other dough factors. Furthermore, as a result of contamination, e.g. by sticking baking residues, multiple injections can occur on the baking plates with the result that not only the baking product becomes unusable but also the baking plate and the mechanical parts of the tong carriage can become damaged. 
         [0006]    Hitherto, many of these disturbances of the baking process could only be determined after the baking process by means of the defective baking products, with the result that particularly in the case of fast-running baking ovens, considerable wastage occurs. 
       SUMMARY OF THE INVENTION 
       [0007]    It is therefore the object of the present invention to avoid the said disadvantages by taking measurements during the baking process by measuring pressure and/or temperature directly in the baking plate and as close as possible to the baking surface and thereby have the possibility of controlling the baking parameters in good time. In the event of a set-point value deviation, the operator of the baking oven should be able to regulate the parameters such as temperature, amount of dough, recipe and belt speed, for example, by means of the measurement data. Furthermore contaminations, wear effects and double injections thereby caused can be avoided. One aim is also the fully automatic regulation of the baking oven control by means of the measured parameters. 
         [0008]    The apparatus according to the invention is intended to be used for all baking ovens in which regulation using the parameters temperature and pressure is appropriate. In particular, these are wafer baking ovens for the production of crispy flat wafers, wafer products having three-dimensional shaping, flat baking products which are shaped three-dimensionally in the heated state after the baking process, and also soft waffles. The industrial technical operating mode of these baking ovens is accomplished by means of circulating baking tongs which are arranged in a row, where the baking tongs each comprise an upper and a lower baking plate and the baking tongs are opened for receiving dough, pass through the baking chamber after closing, and after baking of the product are opened again to remove the baking product, then cleaned and supplied to the dough application station again. This prior art is already described, for example, in AT 378 470 B1 and the similar U.S. Pat. No. 4,438,685. 
         [0009]    The invention solves the formulated object whereby at least one baking plate is provided whose baking surface can be heated to baking temperature, where the baking plate has a sensor device for detecting the temperature of the baking plate and/or of the pressure acting on the baking surface of the baking plate during the baking process. The sensor device contains at least one sensor. The sensor is preferably disposed in a sensor receiving opening in the baking plate so that the sensor lies with its sensor head in the baking surface or comes to lie in close proximity to the baking surface. The sensor receiving opening is configured to extend from the rear side of the baking plate to a measuring section in close proximity to the baking surface, where the baking surface and the measuring section run through continuously. 
         [0010]    Alternatively the sensor receiving opening can penetrate from the rear side of the baking plate through the baking plate where the sensor head lies with its sensor membrane in the baking surface and is profiled the same as this. 
         [0011]    The measuring section of the sensor receiving opening can have a stamp projecting towards the sensor head or the sensor membrane thereof for transmitting the measurement values acting on the measuring section. Alternatively, the sensor membranes can have a stamp projecting towards the measuring section. The measuring section has, for example approximately a wall thickness between 1 and 3 mm. 
         [0012]    The sensor receiving opening can be configured as a blind hole projecting into the baking plate and the sensor with its sensor body can be cylindrically shaped and fastened in the baking plate by means of an annular clamping element. Furthermore, the sensor is a passive temperature-pressure sensor which can preferably be interrogated by means of an electromagnetic field, which on its rear side has a sensor antenna for transmission of energy and information. The sensor antenna is an H-slot antenna. A reflector plate is disposed below the sensor antenna which is fastened to the sensor body or its shaft. 
         [0013]    One or more reading devices are assigned to the sensor, which produce and evaluate the electromagnetic field. The sensor is adapted to deliver information relating to pressure, temperature and an identification feature characteristic of the sensor. The baking plate can also have a plurality of sensors. The baking plate can be part of baking tongs circulating in the baking oven, which each comprise a lower and an upper baking plate where the baking tongs in the closed position loaded with dough are movable through the baking chamber. The sensor device can consist of one or more sensors on the upper and/or lower baking plate. At least one of the baking tongs circulating in the baking oven is provided with at least one sensor device. A plurality of or all the baking tongs of a baking oven can be provided with a sensor device. In the baking oven a position display displaying the position of each baking tong and its baking plates provided with the sensor device is preferably provided in order to be able to assign each measured value read by the reading device to a specific baking plate and baking tong and its position in the baking oven. One or a plurality of reading devices are provided consecutively in the baking chamber and the successively read measured values and the identification features of the sensor devices of the baking plate(s) are fed to an evaluation device. Advantageously SAW sensors based on piezoelectric substrate crystals are used as sensors. Furthermore, the apparatus is preferably a baking oven for producing baked products which are formed in a baking tong between two successively disposed baking plates, wherein the baking oven has an oven frame provided with an external thermal insulation and baking tongs circulating in the baking oven are provided, which are disposed along an orbit leading through the baking chamber of the baking oven and which are conveyed by the conveying device of the baking oven along the orbit through the baking oven, wherein in the oven frame on a part of the orbit of the baking tongs disposed outside the baking chamber, a device for opening the baking tongs, a dispensing station for the baked products, a loading station for loading the baking tongs and a device for closing the baking tongs in the running direction of the baking tongs are disposed consecutively and wherein there is provided a monitoring device integrated in the baking oven, which detects the work activity of the baking oven and the baking process taking place in the baking tongs, which is provided with: 
         [0014]    a sensor device which comprises at least one sensor disposed on a baking tong, which detects the baking process taking place in the baking tong, which is configured as a passive sensor which can be interrogated by an electromagnetic field, 
         [0015]    a transmitting and receiving device which is disposed fixedly in the baking oven and comprises at least one reading device disposed on the orbit of the baking tong chain, which communicates via the electromagnetic field with the sensor of the sensor device and 
         [0016]    an evaluation device which processes the signals coming from the sensor via the reading device and produces monitoring signals. 
         [0017]    Further features of the invention can be deduced from the claims, the following description and the drawings. 
         [0018]    Other features which are considered as characteristic for the invention are set forth in the appended claims. 
         [0019]    Although the invention is illustrated and described herein as embodied in a apparatus for producing baked products, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
         [0020]    The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0021]    The invention is explained in detail hereinafter with reference to the drawings. 
           [0022]      FIG. 1  shows an oblique view of two closed baking plates which are assigned to one another and 
           [0023]      FIG. 2  shows a section along the line II-II in  FIG. 1 . 
           [0024]      FIG. 3  shows an oblique view of a baking tong according to the invention and 
           [0025]      FIG. 4  shows a section of a cross-section along line IV-IV in  FIG. 3 . 
           [0026]      FIGS. 5 to 7  show various exemplary embodiments with different arrangements of the sensors in the baking plates. 
           [0027]      FIGS. 8 and 9  show an oblique view and a sectional view of an exemplary embodiment for a baking tong, where the baking plates are not self-supporting but arranged in a supporting frame. 
           [0028]      FIG. 10 a, b    show the inside view of a baking plate half for poured three-dimensional wafer products and the sections through the central die when the mould is closed. 
           [0029]      FIGS. 11 and 12  show two side views of baking ovens in which the baking plates according to the invention can be used with relevant evaluation and reading devices. 
           [0030]      FIGS. 13 and 14  show schematic alternative details. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0031]      FIGS. 1 to 3  show baking plates according to the invention whose fundamental structure corresponds to the prior art. The embodiment shown shows an upper baking plate  1  and a lower baking plate  2 , where these comprise self-supporting baking plates which do not require a supporting frame. In the closed state shown the two baking plates abut against one another at the baking surfaces to such an extent that only the required gap  4  for the dough to be baked remains between the baking surfaces. The baking surfaces can be provided with a fluting in a manner known per se as is known from flat wafers or soft waffles. This fluting is not shown in  FIGS. 1 to 3 . 
         [0032]    As shown in  FIG. 2  in section, the upper baking plate has a sensor device  5  in the form of an individual sensor  6 . The sensor  6  is disposed in a sensor receiving opening  7  in the baking plate, where in this exemplary embodiment the sensor with its sensor head  8  extends close to the baking surface  3  of the baking plate  1 . 
         [0033]    As can also be seen in  FIG. 2 , the sensor receiving opening  7  is substantially orthogonal to the baking surface  3  and the sensor receiving opening extends from the baking plate back  9  into the baking plate. 
         [0034]    As will be explained in further detail subsequently with reference to  FIG. 4 , the sensor with its sensor head  8  extends close to the baking surface  3 , where a thin layer of the material of the baking plate remains between the baking surface  3  and the sensor head or the sensor membrane which terminates the sensor head. The thin region of the baking plate is designated subsequently as measuring section  10 . Located at the other end of the sensor  6  is the sensor antenna  11  which according to  FIG. 1  is configured as an H-slot antenna. The diagrams in these figures are only purely schematic. 
         [0035]      FIG. 3  shows an example for the specific arrangement of the baking plates  1  and  2  in a baking tong. The baking tong can be opened in a known manner and closed again by pivoting the upper baking tong  1  about the baking tong joint  12 . The baking tong forms with the rollers  13  the baking tong carriage and a plurality of such baking tong carriages arranged in a row form the baking tong chain which is guided over an orbit. The control roller  14  is used to control the folding movement of the upper baking plate  1 . 
         [0036]    Further details on the operating mode of such baking devices can be deduced, for example, from the prior art mentioned initially and reference is particularly made to this. 
         [0037]    For the arrangement of the sensor  6  with the sensor antenna  11 , it should also be said that this antenna and its reflector plate  15  should lie as close as possible to the baking plate without however restricting the functionality of the antenna. The sensor antenna  11  can also lie in a slight recess of the baking plate or the baking plate ribs. 
         [0038]      FIG. 4  shows an exemplary embodiment for the arrangement of the sensor  6  in the baking plate. 
         [0039]    The sensor is inserted in the sensor receiving opening  7  and is held by an annular clamping element  30  where this sensor receiving opening is configured as a stepped blind hole. The sensor comprises the sensor head  8  which is closed with the sensor membrane  16  towards the bottom. The sensor receiving opening  7  extends very close to the baking surface  3  of the baking plate, where a measuring section  10  exists between the baking surface and the sensor membrane  16  which is sufficiently thin to relay temperature and pressure relationships on the baking surface  3  rapidly to the sensor head  8 . 
         [0040]    For contact and relaying the parameters between the measuring section  10  and the sensor membrane  16 , there is provided a stamp  17  which in the present exemplary embodiment is configured as a small continuation of the measuring section  10  which extends in the direction of the sensor membrane  16 . 
         [0041]    It is obviously at the discretion of the person skilled in the art to provide the stamp  17  alternatively as part of the sensor membrane  16  and let the stamp act downwards towards the measuring section  10 , as shown in  FIG. 13 . 
         [0042]    The wall thickness of the measuring section  10  is indicated by the reference number  18  and in practice lies between 0.5 and 5 mm, preferably between 1 and 3 mm. The wall thickness of the measuring section depends on the material of the baking plate and the sensitivity of the sensor. It is essential that temperature and pressure can be determined by the sensor in sufficient time and to sufficient extent. 
         [0043]    The measuring section  10  comprises a surface area which is approximately indicated by the arrow  29 . 
         [0044]    A cavity  19  is provided in the sensor head  8  for the actual measuring component of the sensor, in particular the substrate-supported piezocrystal, where the structure of this measurement-sensitive sensor arrangement inside the sensor forms a separate invention and is not shown further here. It is essential that the parameters pressure and temperature transmitted through the measuring section  10  or one of these parameters can be relayed with appropriate accuracy as a signal to the sensor antenna  11 . 
         [0045]    Located above the sensor head  8  is an insulation shaft  20  whose longitudinal extension overcomes the thickness of the baking plate. The reflector plate  15  sits on the insulation shaft  20 . Not shown is the electrical lead which extends inside the sensor from the sensor head  8  as far as the antenna  11  and naturally must withstand the high temperatures of a baking oven. 
         [0046]      FIG. 5  is merely intended to illustrate that instead of in the upper baking plate  1 , the sensor  6  can also be disposed in the lower baking plate  2 . Similarly  FIG. 6  shows the multiple arrangement of sensors either in the lower and/or upper baking plate, in the present example the arrangement of three sensors in the upper baking plate as sensor device.  FIG. 7  shows the arrangement of respectively one sensor in the lower and upper baking plate. 
         [0047]      FIGS. 8 and 9  illustrate the arrangement of a sensor  6  in another embodiment of baking tongs, where the baking plates are not configured to be self-supporting but are mounted in a supporting frame  21 ,  22 . This fundamental design of a baking plate can also be deduced from the prior art and requires no further explanation since the type of assembly of the baking plates alone is not essential to the invention in the present case. The person skilled in the art also identifies that the tong carriage shown comprises a baking plate without locking such as is used, for example, for the production of soft waffles or for the production of baked flatbreads for the subsequent formation of wafer cones. In the same way however, a sensor can also be provided for tong carriages with locking. 
         [0048]    The supporting frame is indicated as upper supporting frame  21  and lower supporting frame  22 . The sensor  6  sits in its sensor receiving opening  7  in the upper baking plate  1 . The sensor extends here so far upwards that it is protected by the supporting frame  21  but the effect of the sensor antenna  11  is not diminished. 
         [0049]      FIG. 10 a    shows schematically the inner view of a die half to produce poured wafer cones, where the sensor  6  is inserted in one of the die recesses  23 , where its own baking surface  32  is provided for the sensor  6 , on which pressure and/or temperature can be measured in similar manner.  FIG. 10 b    shows the cross-section through the central die in the closed state. 
         [0050]      FIG. 11  shows schematically an overview of the entire baking device. After the dispensing-input station  24 , the baking plates provided with the sensor or sensors travel into the baking chamber  25  of the oven. Located in the initial section of the baking chamber is the reader of a radio antenna which emits its electromagnetic field in the direction of the sensors of the passing baking tongs. As a result of the measurement parameters of the sensors, the electromagnetic field varies in characteristic manner, which can be evaluated by the reading device  26 . The reading device delivers its signals via the antenna cabling  27  to the evaluation device  28 , which for example comprises a display for the operator of the baking device, where the display can output appropriate warnings in the event of variations of the baking parameters. The evaluation device can however also provide independent regulation of the baking parameters. 
         [0051]    The precise arrangement of the reading devices or a multiplicity of reading devices along the process section for the baking process can be arbitrary and selected according to the circumstances.  FIG. 12  shows, for example, in the initial part of the baking chamber the arrangement of six reading devices  26  and in addition, a further six reading devices in the returning part of the baking tong chain. This is only to explain that there are numerous possible arrangements. It is therefore possible to track the entire process behaviour of each baking plate and to bring about an optimisation of the baking process. 
         [0052]      FIG. 12  also shows schematically the position display  31  which displays the arrangement in which the baking tong chain is located. The precise assignment of the measurement data delivered by the reading devices  26  to the baking plates and their position in the baking oven is thereby possible. 
         [0053]      FIG. 13  shows schematically an alternative to the arrangement of the sensor in the sensor receiving opening  7 . The stamp  17  which is responsible for transmitting the measured quantities to the sensor head  8  is a fixed component of the sensor membrane  16  and projects downwards to the measuring section  10  of the baking plate. The fluting  33  of the baking surface  3  is not interrupted since the measuring section  10  is continuously one-piece with the baking plate  1 . 
         [0054]      FIG. 14  shows another alternative to the configuration of the measurement arrangement. The sensor receiving opening  7  extends over a section  32  with reduced diameter into the baking surface  3  so that a continuous opening is present. The stamp  17  extends from the sensor membrane  16  through the section  32  as far as the baking surface  13 . If the measurement point of the stamp  17  should not be visually identifiable on the finished wafer product, the stamp  17  can also be provided continuously with the fluting. 
         [0055]    The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention:
     1  Upper baking plate     2  Lower baking plate     3  Baking surface     4  Gap     5  Sensor device     6  Sensor     7  Sensor receiving opening     8  Sensor head     9  Baking plate back     10  Measuring section     11  Sensor antenna     12  Baking tong joint     13  Rollers     14  Control roller     15  Reflector plate     16  Sensor membrane     17  Stamp     18  Arrow     19  Cavity     20  Insulation shaft     21  Upper supporting frame     22  Lower supporting frame     23  Die recess     24  Dispensing-input station     25  Baking chamber     26  Radio antenna, reading device     27  Antenna cabling     28  Evaluation device     29  Arrow     30  Annular clamping element     31  Position display     32  Section     33  Fluting