Abstract:
Provided is a cooking appliance comprising a first structure having a hot plate for cooking food, and a measuring device for measuring the thickness of the food arranged thereon and comprising a pivoting rocker connected to a pivotable shaft by a first end thereof, and a means for measuring the pivoting angle of the rocker in order to estimate the thickness of the food. The appliance comprises a second mobile structure which, when moved away from the first structure, generates a pivoting of said shaft in relation to the first structure, causing the pivoting of the rocker, and the measuring means interacts with the rocker towards a second end thereof.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the United States national phase of International Application No. PCT/FR2013/051365 filed Jun. 12, 2013, and claims priority to French Patent Application No. 1255600 filed Jun. 15, 2012, the disclosures of which are hereby incorporated in their entirety by reference. 
     The invention concerns a cooking appliance for cooking a food and a method for implementing the same. 
     FIELD OF THE INVENTION 
     The present invention concerns the field of cooking appliances comprising at least one heating plate for cooking a food such as, meat, fish, vegetables or others. More precisely, the invention concerns a cooking appliance allowing to determine the thickness of foods contained in the appliance. 
     PRIOR ART 
     A food cooking appliance of this type is known from document DE 4 302 190. The latter describes a cooking appliance comprising a first structure including a heating plate for cooking a food and a measuring device for measuring the thickness of the food in the appliance. The measuring device is equipped with two pivoting rockers, each connected by a first end to a pivotable shaft. The measuring device also comprises a means for measuring the pivoting angle of the rocker to estimate the thickness of the food. 
     However, this appliance does not allow estimating very reliably the thickness of the food and is not easy to use. 
     OBJECTIVES OF THE INVENTION 
     The invention aims in particular to overcome all or part of the drawbacks of the prior art. 
     More precisely, an objective of the invention is to provide a cooking appliance allowing to determine the thickness of foods in order to control and obtain an automatic cooking of foods. 
     The invention further aims to guarantee the quality of food, in particular the organoleptic quality, since the cooking time will depend, among others, on the thickness. 
     SUMMARY OF THE INVENTION 
     These objectives are achieved by means of a cooking appliance comprising a first structure comprising a heating plate for cooking a food and a measuring device for measuring the thickness of the food thus disposed and comprising:
         a pivoting rocker connected by a first end to a pivotable shaft; and,   a means for measuring the pivoting angle of the rocker to estimate the thickness of the food.       

     The invention is remarkable in that the appliance comprises a second movable structure, of which a separation movement relative to the first structure generates a pivoting of said shaft relative to the first structure, resulting in the pivoting of the rocker, and the measuring means interacts with the rocker toward a second end thereof. 
     Thus, the second movable structure allows an adaptability of the appliance to the thickness of the food, and the existing distance then between the two structures allows determining very reliably the thickness of the food. Preferably, the first structure will cook thereagainst the food. 
     According to an important feature, the second structure comprises a heating plate adapted to cook thereagainst, by conduction, said food disposed between the plates. 
     Accordingly, the food can be cooked uniformly and more quickly since the two sides of the food are in contact with the heating plates. 
     According to one embodiment, the rocker is rigidly connected to the pivotable shaft or is mounted on the shaft with a clearance sufficient to allow the pivoting of the rocker about the shaft. All scenarios for allowing a pivoting of the rocker are considered so that the mounting is simple. 
     Advantageously, the second structure is mounted on the shaft by means of lateral arms movable at least relative to the first structure. 
     This arrangement allows facilitating the mounting and a time saving during manufacturing. 
     Preferably, each lateral arm comprises a first end connected to the shaft and a second portion connected to a flank of the second structure toward the middle thereof. 
     The arm thus arranged allows an average measurement of the food and the management of the lack of parallelism between the two structures. 
     According to another important feature, the rocker includes a first end engaged with a first end of one of the lateral arms where the arm is connected to the shaft, this engagement operating until a predetermined pivoting angle of the arms beyond which said arm disengages from the rocker, so that the lateral arms then continue their pivoting without the rocker continuing to pivot. 
     This arrangement, on the one hand, allows increasing the resolution of the measurements over a range approximately corresponding to a food thickness, and on the other hand, allows the second structure to open without continuously biasing the measuring means. 
     Advantageously, the predetermined pivoting angle of the arms corresponds to the predetermined pivoting angle of the rocker which is comprised between 10° and 30°. 
     According to another advantageous feature, the predetermined pivoting angle of the rocker corresponds to an intermediate open state of the first and second structures where they are substantially parallel. 
     According to an important feature, the rocker is connected, toward its second end, to a means for actuating the measuring means. This arrangement allows the rocker to easily actuate the measuring means, thereby giving an image of the angle covered at the arm and therefore an accurate information about the separation of the structures and thus the thickness of the food. 
     According to a preferred embodiment, the measuring means comprises a potentiometer. 
     The use of a potentiometer is a simple, very cost-effective and easy mountable solution. 
     Advantageously, the rocker comprises a first and a second fingers, the actuating means for actuating the measuring means forms a lever driven by the second finger and biased by a biasing means which holds the rocker and the lever in contact during the separation movement of the second structure. The use of a lever allows the rocker to drive the measuring means upon the opening of the second structure. In addition, the biasing means allows reducing the construction clearances. 
     According to another embodiment, the actuating means comprises a toothed wheel driven by a rack of the rocker and biased by a biasing means which holds the rocker and the toothed wheel in contact during the separation movement of the second structure. 
     According to another embodiment, the measuring means comprises a strain gauge. The use of a strain gauge is a solution that is also simple and applicable on the appliance such as aforementioned and not requiring its modification. 
     According to another embodiment and for simplicity, the measuring means comprises an optical detection system with a photodetector. 
     The invention also concerns a method for implementing a food cooking appliance. This method comprises a step of adjusting the appliance, before use, through the selection by a user of a key or a combination of keys that the appliance comprises. 
     Thus, all errors and uncertainties due to the repeated use and to the wear of the parts are compensated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the invention will become apparent from the description which is given therefrom hereinafter, by way of indication and without limitation, with reference to the appended drawings, in which: 
         FIG. 1  is a perspective view of the cooking appliance according to the invention; 
         FIG. 2  is an exploded view of the appliance according to the invention; 
         FIG. 3  is a side view of the open appliance; 
         FIG. 4  is a detailed view of the measuring device mounted on the appliance according to  FIG. 2 ; 
         FIG. 5  is a side view of the closed appliance; 
         FIG. 6  is a detailed view of the measuring device mounted on the appliance according to  FIG. 4 ; 
         FIG. 7  represents an internal view of an arm of the appliance; 
         FIG. 8  is a side view of the rocker; 
         FIG. 9  represents a perspective view of the appliance according to another embodiment; 
         FIGS. 10A, 10B and 11  are schematic representations of other embodiments of the measuring device according to the invention; 
         FIG. 12  shows in a more detailed way the measuring device according to the invention; 
         FIGS. 13 and 14  represent the engagement means of the rocker and the arm; 
         FIG. 15  illustrates an alternative of the rocker; 
         FIG. 16  is a detailed view of a portion of the potentiometer; 
         FIG. 17  is a perspective view of another alternative of the potentiometer according to  FIG. 16 ; 
         FIG. 18  is a detailed view of another embodiment of the measuring means; and 
         FIG. 19  illustrates a portion of the potentiometer. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates a household appliance  1  comprising a first structure  2  which includes a lower heating plate  3 , for cooking a food and a measuring device  12  for measuring the thickness of the food placed in the appliance  1 . 
     The food(s) can be meat, fish, vegetables, or others. 
     The measuring device  12  represented in  FIGS. 2 to 6, 8 , and  10 A,  10 B to  19  comprises a rocker  6  pivotable in the appliance  1 . The rocker  6  exhibits a first  7  and a second  8  ends, the first end  7  being connected to a shaft  9  pivotable about an axis of rotation A. 
     The rocker  6  can be rigidly connected to the shaft  9 , for example by being tightly mounted around it. Thus, when the shaft  9  pivots or rotates, it also drives the rocker  6  in rotation. It can be also provided that the rocker  6  is mounted on the shaft  9  with a clearance sufficient to allow the rotation or the pivoting of the rocker. Unlike the alternative with the rigidly mounted rocker, when the shaft  9  rotates, the rocker pivots through other means connected to the shaft  9  which will be described later in the description. 
     The measuring device  12  also comprises a means  10  for measuring the pivoting angle of the rocker  6  allowing to estimate the thickness of the food which is described hereinafter. 
     It is provided that the appliance  1  is equipped with a second structure  4  movable relative to the first structure  2  to produce a separation movement. 
     The second structure  4  also comprises an upper heating plate  5 , which is adapted to cook thereagainst, by conduction, the food(s) disposed between the lower  3  and upper  5  heating plates. More precisely, the food is cooked against the two heating plates  3 ,  5 . 
     In one alternative, it can be considered that the second structure  4  consists of a lid for example, for covering the first structure  2 . 
     Each structure  2 ,  4  is formed, for example, of a shell and comprises lateral flanks  11 . The shell can be made of a metal or a polymer, for example. The second structure  4  can comprise on its shell a handle  46 , preferably made of thermoplastic and insulating, to allow the opening and the closing of the appliance  1 . The first structure  2  can comprise feet  45  for the positioning of the appliance  1  on a flat support, for example. The feet  45  can be formed by molding with the shell of the second structure  4  or fixed on the shell with screws, or other adequate means. The foot  45  is covered with a wall  56 . A collection tray  53  of cooking juice can also be provided. 
     The first  2  and second  4  structures exhibit a closed state in which they each extend along a plane P substantially horizontal and parallel relative to each other, and an open state in which they form, for example, a substantially dihedral shape with a separation angle of about 100° (when the second structure  4  is rigidly fixed to the shaft  9 ,  FIG. 9 ). Thus, the food to be cooked will be disposed horizontally between the lower  3  and upper  5  heating plates. 
     Each heating plate  3 ,  5  is heated by an electrical resistance (not represented) supplying them with the energy required for cooking the food. The electrical resistance is generally located between the shell and the heating plates  3 ,  5 . Preferably, the heating plates  3 ,  5  are removable and can be coated with a non-stick coating. 
     According to the invention, the separation movement of the second structure  4  relative to the first structure  2  generates a rotation of the shaft  9  relative to the first structure  2 , thereby resulting in the pivoting of the rocker  6 . In the case where the rocker  6  is rigidly fixed on the shaft  9 , the pivoting of the shaft  9  causes the pivoting of the rocker  6 . The measuring means  10  can interact with the rocker toward the second end  8  of the rocker  6 . 
     The second structure  4  can be mounted on the shaft  9  by means of lateral arms  13  ( FIG. 7 ) movable relative, at least, to the first structure  2 . More precisely, each lateral arm  13  comprises a first end  14  connected to the shaft  9  and a second portion  15  connected toward the middle  16  of a flank  11  of the second structure  4 . The second portion  15  can be formed by a second end  47  of the arm  13 . In this present embodiment, this second end  47  is secured to the handle  46 . 
     More precisely, the first end  14  of the lateral arms  13 , as can be seen in  FIG. 12 , includes an opening  17  with an inner surface fitted with flat sections  18 , here two flat sections, intended to cooperate with the end  19  of the shaft  9  which also includes a flat section  20  in order to create a fixed connection between the shaft  9  and the arms  13 . The assembly can be tightened further by a screw  48  through the opening  17  of the arm  13  and an opening  49 . To facilitate the guiding of the arm, the wall  56  covering the foot  45  can exhibit a groove  55  in which a pin  54  slides. The second portion  15  of the arms  13  includes an opening  21  for the passage of a screw  22 , for example, which will be screwed at the middle  16  of the flank  11  of the second structure  4 . The latter can be fixed relative to the arm  13  or preferably movable in rotation through a pivot connection created by the screw  22  and the opening  21 . A pivot connection will allow an adjusting of the second structure  4  in a manner substantially parallel to the first  2  one so that the cooking of the food is uniform. However, the mobility of the second structure  4  relative to the arm  13  can be blocked thanks to a female member, of the trunnion type, mounted on the shell of the structure  4  cooperating with a male member, of the notch type, provided on the inner face of the arm  13 , suitable to define a connection via obstacle. 
     In an alternative of the appliance  1  schematized in  FIG. 9 , it can be considered that the latter has no arms  13 . In this case, it is the movement of the second structure  4  which is tightly and rigidly mounted with the shaft  9  which causes the pivoting of the rocker  6 . 
     As previously seen, the rocker  6  can be rigidly connected to the shaft  9 . For this, the first end  7  of the rocker  6  includes an orifice  23  whose the inner surface can be fitted with a flat section (not represented) facing the flat section  20  of the shaft  9  to create a fixed connection. However, the rocker  6  can be tightly mounted through the fastening of the arm  13  on the shaft  9 . Accordingly, by pivoting the lateral arms  13  and/or the second structure  4  to open the appliance  1 , the shaft  9  is driven in rotation, thereby simultaneously driving the rocker  6  in rotation. 
     The rocker  6  exhibits a length of about 100 mm. The latter can, for example, be made of plastic, metal, or another material. 
     The first end  7  of the rocker  6  can be engaged with the first end  14  of one of the lateral arms  13  where the rocker  6  is connected to the shaft. The engagement between the rocker  6  and the arm  13  is obtained by means of a first finger  25  located on the outer face  24  of the first end  7  of the rocker  6 . The first finger  25  allows a rear portion  50  of the arm  13  to bear thereon during the displacement of the arm  13 . For example, this engagement operates until a predetermined pivoting angle α of the arm  13  (see  FIG. 4 ), the latter disengaging then from the rocker  6  beyond said predetermined angle α, so that the lateral arms  13  then continue their pivoting, toward a fully-open position of the arms  13  and/or the first  2  and second  4  structures, and without the rocker  6  continuing to pivot. 
     In the case where the rocker  6  is mounted with a clearance on the shaft  9 , the latter is rigidly mounted with the arm  13 . In particular, the mounting is performed by means of a flat section  20  of the shaft  9  cooperating with the flat section  18  of the inner surface of the opening  17  of the arm  13 . The pin  54  provided on the arm  13  is advantageously intended to come into contact with the first finger  25  that the rocker  6  comprises. By pivoting the arm  13 , the pin  54  abuts against the first finger  25  thus causing the rotation of the rocker  6 . In order that the arms  13  and/or the first  2  and second  4  structures continue their pivoting toward the fully-open position, it can be provided that the pin  54  consists of a flexible blade. The latter would allow the disengagement of the arm  13  of the rocker  6  beyond the predetermined pivoting angle α of the arm. Of course, other solutions can be considered so that the disengagement of the arm  13  and the rocker  6  is performed. 
     The predetermined pivoting angle α of the arm  13  corresponds to a predetermined pivoting angle β of the rocker  6  which is comprised between 10 and 30° (illustrated in  FIG. 4 ). Preferably, the predetermined pivoting angle β of the rocker  6  is in the order of 24°. More precisely, the predetermined pivoting angle β of the rocker  6  corresponds to an intermediate open state of the first  2  and second  4  structures, and/or the arms  13 , where the separation of said structures  2 ,  4  is in a manner substantially parallel. The intermediate open state of the first  2  and second  4  structures then exhibits a separation comprised between 30 and 60 mm. Preferably, this separation is of 40 mm. 
     The rocker  6  comprises on its second end  8  a means for interacting with the measuring means. 
     More precisely, the second end  8  of the rocker  6  can comprise on its inner face  51  a second finger  26  intended to set a connection between the rocker  6  and an actuating means  60  for actuating the measuring means  10 . 
     The measuring means  10  can comprise, for example, a potentiometer  27 , a strain gauge, an optical detection system  29  with a photodetector or an electromagnetic detection system. The measuring means  10  is preferably installed in one of the rear feet  45  to avoid temperature variations. 
     In the embodiment comprising the potentiometer  27 , the latter includes a body  59  and a cavity  36  opening into the body  59 . The potentiometer  27  also includes a lever  30  driven by the second finger  26  of the rocker  6 , between the closed state and the intermediate open state of the first  2  and second  4  structures. 
     Advantageously, the measuring means  10  also comprises a biasing means  32 . 
     In particular, the lever  30  exhibits a distal end  31  that can be biased by the biasing means  32  which holds the rocker  6  and the lever  30  in contact, at the second finger  26 , during the separation movement of the second structure  4  for example, or the movement of the arms  13 . The biasing means  32  can be fixed by one of its ends  33  to the frame of the appliance  1  and by the other of its ends  33  to a passage  52  that the distal end  31  of the lever  30  can comprise. 
     The lever  30  also includes a proximal end  34  fitted with a head  35  which is intended to be engaged in the cavity  36  of the potentiometer  27 . The lever  30  is movable in rotation along an angle γ comprised between 0° and 65°. The lever can include a length of about 20 mm. 
     According to another alternative of this embodiment as illustrated in  FIGS. 15 to 19 , the measuring means  10  comprises the potentiometer  27 . The latter includes a toothed wheel  58  installed inside the body  59  of the potentiometer  27 . However, a portion of the toothed wheel  58  remains accessible out of the body  59 . More precisely, the toothed wheel is driven by a rack  58  that the end  8  of the rocker  6  comprises. The teeth of the wheel can be disposed over all or part of the periphery thereof. The biasing means  32  can be housed inside the body  59  of the potentiometer to hold the rocker  6  and the lever  30  in contact during the separation movement of the second structure  2 . 
     The biasing means  32  can comprise a first  61  and a second  62  biasing elements. The first biasing elements  61  can be housed in the measuring means  10 , for example in the body  59  of the potentiometer  27  and/or the second biasing element  62  can be fixed on the one hand to the frame and on the other hand to the distal end  31  of the lever  30 . 
     This biasing means  32  allows returning the rocker  6  when it is released upon the complete opening of the appliance  1  and overcoming the problem of clearance related to the manufacture. Preferably, it consists of a tension spring and/or a spiral spring. 
     The potentiometer  27  can be used without limitation. It can exhibit an angular range varying from 0 to 90°, from 0 to 120° or even from 0 to 360°. It can be provided that the potentiometer  27  is equipped with a built-in, an offset or an integrated printed circuit. 
     In the embodiment comprising the strain gauge  28  illustrated in  FIGS. 10A and 10B , the latter is disposed, for example on a wall  37  of the rear foot  45 . The second end  8  of the rocker  6  includes a housing with an opening  38  in which is housed a needle  39  passing through the opening  38  when the rocker  6  pivots. The needle  39  is mounted on a spring  40  and acts on the strain gauge  28 . 
     On  FIG. 11 , there is schematically represented an example of optical detection system  29  with a photodetector comprising a LED  41  and a photodetector  42  disposed for example away from the frame, inside the foot  45 . A reflecting element  43  can be mounted on the second end  8  of the rocker  6  to reflect the light ray toward the photodetector  42 , thereby allowing to estimate the thickness of the food. 
     Concerning the electromagnetic elements provided for the measuring means, these can consist, for example, of a Hall-effect sensor. 
     Thanks to the arrangement of the measuring device  12 , it might be possible to establish an amplification ratio of the pivoting angle β of the rocker (or the angle of the lateral arm  13 ) greater than 3 to allow differentiating thicknesses of food at +/−1 mm. This ratio can be written as follows: 
     
       
         
           
             
               R 
               amplification 
             
             = 
             
               
                 
                   L 
                   rocker 
                 
                 
                   L 
                   lever 
                 
               
               = 
               
                 
                   
                     β 
                     lever 
                   
                   
                     α 
                     rocker 
                   
                 
                 &gt; 
                 3 
               
             
           
         
       
     
     In order to optimize the achieved results so that they are accurate and for a better cooking of the food, there can be provided a calibration or sizing of the appliance  1  in factory, after manufacture. For more accuracy, the calibration consists in measuring the same quantity with the appliance with gauge blocks. 
     For example, a first gauge block intended to simulate a food thickness can be installed between the first  2  and second  4  structures so as to obtain a first value, called first point. The first block can exhibit a thickness of about 2 mm. 
     A second gauge block is then disposed between the first  2  and second  4  structures in order to obtain a second value, called second point. The second block can exhibit a thickness of about 30 mm. 
     These first and second points will allow determining, through different simulations, the uncertainties related to the measurements performed by the appliance  1  during calibration and, of course, correcting them. 
     When the appliance is sold and ready operate, a user can use it as follows:
         Turning-on of the appliance  1  by pressing, for example, an on/off button or key of an interface  44  that the appliance  1  exhibits. The latter can be for example turned on, by plugging a power cord that it comprises in order to connect it to the mains.   If provided, selection of the type of food by means of the interface  44 .   If still provided, selection of a desired cooking degree of the food. Otherwise, there can be provided a determination, by the appliance  1 , of the cooking temperatures depending on the food.   If still provided, automatic determination of the preheat temperature of the appliance  1 .   Opening of the appliance. This step can be performed at any time of the aforementioned steps.   Setting up of the food.   Closure of the appliance  1  by lowering the second structure  4  and/or the lateral arms  13  above the food.       

     This step will allow the appliance  1  to perform the measurements of thickness of the food then disposed between the first  2  and second  4  structures, and will allow, for example, activating the beginning of the cooking of the food. Said thickness measurement is automatically obtained by the pivoting angle β of the rocker  6 . The latter allows determining the separation between the first  2  and second  4  structures in order to estimate the thickness of the food.
         At the end of the cooking of the food, the user can retrieve the food or keep it warm between the structures  2 ,  4 .   The appliance can be turned off by selecting the on/off key or be unplugged.       

     The interface  44  can exhibits different keys or buttons allowing to access a menu or a touch screen. 
     To ensure that the mechanical and/or electronic system of the appliance  1  operates in an optimal manner and to compensate all errors and uncertainties that appear due to several uses and/or ageing of the appliance  1 , it can be provided that the user performs an automatic adjustment of the appliance  1 . This adjustment is preferably performed with the grill closed. It is intended to reset the measuring device  12  to an operating state appropriate for its use. For example, in the case where the grill is closed, the device is reset to 0, value indicating that there is no food thickness in the appliance  1 . 
     For example, the user can, before use, press an adjustment key or set a combination of keys to achieve the adjustment.