Abstract:
A cooking vessel with a frying fat heating device which increases the useful life of the frying fat, and improves the evenness of cooking in the frying fat.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The invention relates to a cooking vessel with a frying fat heating device for a deep frying appliance for the ‘floating’ frying of food portions and luxury foodstuffs.  
         [0002]     By ‘floating frying’ is meant the preparation of food or other luxury items (in the following referred to simply as ‘food’), characterised in that the food is cooked in hot deep fat, ie. appropriately cooked through for consumption. For this type of food preparation, the term ‘deep frying’, and for equipment for deep frying the term ‘deep fat frier’, have become accepted, and these are used in the presentation of the invention. Deep fat friers are used in particular for the preparation of bulk items which are prepared in the form of equally sized strips.  
         [0003]     A bulk item of the type described, often intended for consumption, is potatoes which are prepared for consumption by deep frying. Such bulk items are generally known under the term ‘chip portions’.  
         [0004]     Equipment for the production of chip portions is established which produces the latter from a raw or pre-cooked bulk material, manually or automatically. The established automatic equipment here essentially comprises a storage container for uncooked chips and a cooking vessel (in the following also referred to as a deep frying drum), whereby the storage container is connected to the deep frying drum by means of a pipe connection.  
         [0005]     A scooping device operating in the storage container forms a pile of the pre-determined quantity and feeds this into the pipe which conveys the bulk into the deep frying drum. In the deep frying drum, the bulk is cooked through in hot oil, and then carried out of the deep frying drum.  
         [0006]     A turning element turns in the deep frying drum containing the liquid frying fat, and said turning element comprises radially projecting rakes around its circumference, positioned at equal distances around said circumference, which convey the bulk material through the hot frying fat for cooking and then carry it out of the appliance. In so doing, the frying fat becomes stale, and so must be changed periodically. It is changed by means of a discharge cock which carries the stale frying fat out of the deep frying drum, whereby the deep frying drum is then filled back up again on its front side. The appliance must be cleaned before refilling, and this takes a lot of time and effort in order to keep the equipment in a hygienically sound state. It is the frequency of the time and effort taken to do this as well as the cost of the frying fat to be changed which determines the cost-effectiveness of a deep frying appliance.  
         [0007]     The frequency of the changes of frying fat depends greatly upon the type of heating, ie. heating up, and the homogeneity of the heat distribution in the frying fat. Deep frying drums are known with direct and with indirect frying fat heating. Direct frying fat heating means that the heating is by means of heating elements located in the frying fat (heating within the deep frying drum), and indirect heating means that the frying fat is heated by means of a cyclical heating device outside of the deep frying drum (heating outside of the deep frying drum). Heating in a vessel by warming the vessel walls by means of heat sources which act upon the outer surface of the vessel walls also falls into the category of indirect heating.  
         [0008]     With the first case of indirect heating, the frying fat or deep frying oil is pumped out of the drum, conveyed through the cyclical heating device, and subsequently pumped back into the drum. There are disadvantages associated with these types of heating. The direct heating brings about convection in the liquid frying fat, ie. so-called equalisation currents intended to distribute heat evenly through the frying fat. If a portion of material to be cooked is introduced into the frying fat, the convection and heat distribution is easily disrupted, and the items to be cooked are not cooked through sufficiently. These problems relating to convection also occur with indirect heating in a container by means of heat sources which act upon the vessel from outside. In order to counter these, heating temperatures for the frying fat are set higher than actually required, ie. at an inflated level. It is this inflated heating output which contributes significantly to the deterioration of the frying fat, and so also to increased frequency of the changes. With the indirect heating method by means of a so-called cyclical heating device, the method used is a circulation process.  
         [0009]     Because a pump sucks frying fat out of a cooking drum or a cooking vessel, feeds it through the heating device and conveys it back into the cooking drum, the circulating quantity of frying fat brings about a certain current in the frying fat which gives rise to problems of convection in the background. In the pumps, on the other hand, the liquid frying fats are subjected to mechanical forces which lead to premature deterioration, and so also to frequent changes of the frying fat.  
       SUMMARY OF THE INVENTION  
       [0010]     The object of this invention is to provide a cooking vessel with heating, with which the disadvantages of the established cooking vessels can be avoided, and this problem is solved by the cooking vessel of the present invention wherein the frying fat heating device has a hollow cylindrical conduction sleeve with heating elements accommodated within the conduction sleeve and a current space connected with the conduction sleeve via a floor space. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     Further advantages, features and details of the invention can be found in the following description of a preferred embodiment and the drawings:  
         [0012]      FIG. 1  shows a frying fat heating device in a cooking vessel in a side view and in a section,  
         [0013]      FIG. 2  shows the representation in accordance with  FIG. 1  in an overhead view,  
         [0014]      FIG. 3  shows the representation in accordance with  FIG. 1  in an overhead view along the intersection line A-A in  FIG. 1 ,  
         [0015]      FIG. 4  shows a frying fat heating device combined with a cooking vessel in a front view and in a section,  
         [0016]      FIG. 5  shows an overhead view onto the frying fat heating device in accordance with  FIG. 4  along the intersection line A-A in  FIG. 4 ,  
         [0017]      FIG. 6  shows an overhead view onto the frying fat heating device in accordance with  FIG. 4  along the intersection line B-B in  FIG. 4 ,  
         [0018]      FIG. 7  shows the frying fat heating device with the cooking vessel in accordance with  FIG. 4  in a side view. 
     
    
     DETAILED DESCRIPTION  
       [0019]      FIG. 1  and  FIG. 4  show the cooking vessel  10  with a frying fat heating device  11  of the design in accordance with the invention (in the following referred to as heating device  11  for short). The term cooking vessel should be understood as meaning any container which, for the cooking of portions of food, eg. portions of chips (in the following referred to as items to be cooked), contains frying fat  15 , eg. frying oil, whereby changeable heat contents can be set for the frying fat  15 , and that comprises devices for introducing and removing the items to be cooked into and from the container, ie. the frying fat. The cooking vessel  10  in accordance with  FIG. 1  comprises, as a container, a pot  12 , in which the heating device  11  and a receptacle  13  for introducing and removing the items to be cooked into or from the frying fat are accommodated. The receptacle  13  is preferably a basket made from wire, through the wall sections of which the liquid frying fat can flow, and which is hung loose on the upper open end  14  of the receptacle  13  so that it can be introduced into and removed from the frying fat.  
         [0020]     The heating device  11  is located between the floor  17  of the pot  12  and the floor  18  of the receptacle  13 , ie. the basket. The heating device  11  comprises a circular current conduction sleeve  19  (in the following referred to as conduction sleeve  19  for short) spaced apart from the floor  17  of the pot  12  in which a heating element  20  and a conveyance device  21  following the heating element  20 , ie. between the heating element  20  and the floor, spaced apart from the heating element  20 , are accommodated. The heating element  20  is an electrically powered heating rod which is bent in a serpentine shape and the cross-section of which is in the form of a circular disc, ie. round. The outer diameter of the heating element  20  is of proportions which mean that the heating element  20  can be introduced into the interior space of the conduction sleeve  19 . The individual bent sections  22  of the heating element  20  are spaced apart from one another so that frying fat can pass through the heating element  20  taking in heat. The conveyance device  21  is in the form of an externally driven propeller, preferably with four blades  24 , and which, like the heating element  20 , is located in the interior space of the conduction sleeve  19 , such that it can rotate. Preferably, the propeller blades  24  can have an adjustable angle (not shown) set to the rotational axis  23  of the conveyance device  21 , which moves in the range of one to ten angle degrees, preferably four to eight angle degrees. The heating element  20  is moved from the upper edge (edge below the floor  18  of the receptacle  13  or on the up-current side) of the conduction sleeve  19 , axially in the direction towards the lower edge (edge above the floor  17  of the pot  12 , or on the down-current side) of the conduction sleeve  19 , so that a circular space  25  is formed above the heating element  20 , the propeller, ie. the conveyance device  21  coincides axially with the lower edge of the conduction sleeve  19 . Because the outer diameter of the conduction sleeve  19  is smaller than the internal diameter of the pot  12  and the lower edge of the conduction sleeve  12  is spaced apart from the floor  17  of the pot, a current space  31  is created below and around the conduction sleeve, formed from a flat cylindrical floor space  26  and a riser pipe  27  for the removal of heated frying fat, which has travelled through the conduction sleeve  19  with the heating element  20  and the conveyance device  21 . The circular space  25  has proven advantageous for the evenness of heating of the frying fat. In connection with FIGS.  1  to  3 , the pot  12 , receptacle  13  and conduction sleeve  19  were described as cylindrical in form. However, the frying fat heating device  11  is not limited to this form. For example (see  FIGS. 5 and 6 ) an appendage  35  for the current conduction sleeve  19  can be multi-sided, and the current conduction sleeve  19  can be round. The mode of operation for the frying fat heating device  11  in accordance with the invention is as follows. Cooled frying fat  15  is conveyed from the frying fat supply (see level line  28 ) through the conduction sleeve  19  by gravitation and falling, supported by the effect of the activated conveyance device  21  (drive not shown). In so doing, the frying fat  15  is heated as it flows through the heating element  20  and moved on by the conveyance device  21  in the direction of the floor space  26 , from where the frying fat  15  climbs, passing through the riser pipe  27 , due to its greater heat content and driven by the conveyance device  21  in the direction of the frying fat supply, and mixes with the cooler supply of frying fat. This is shown schematically by the current arrows  30 . With the embodiment of the frying fat heating device in accordance with the invention, very homogeneous heat distribution is achieved in the frying fat  15 , and any mechanical forces are avoided.  
         [0021]     While the embodiment in accordance with FIGS.  1  to  3  is designed more for manual operation, whereby items to be cooked are introduced into and removed from the frying fat  15  using the receptacle  13 , ie. the basket, the embodiment in accordance with FIGS.  1  to  7  schematically shows a fully automatic cooking appliance. The cooking vessel  10  here is drum-shaped, and in the form of a hollow cylinder lying on its side, in which the frying fat  15  is received, and into which the items to be cooked are fed in through an entrance  32 , moved by means of a rotating turning element  33  for cooking with the frying fat  15 , and carried out via an exit device  34  once cooking is completed. If one identifies the circumference of the cooking vessel  10  with the entrance  32  as the upper side of the cooking vessel  10 , the frying fat heating device  11  in accordance with the invention is positioned perpendicularly in relation to the upper side on the lower side of the cooking vessel  10 . The frying fat heating device  11  in accordance with FIGS.  4  to  7  consists of a box-shaped appendage  35 , the cross-section of which is rectangular and preferably has the same length as the hollow cylinder of the cooking vessel  10 . The appendage  35  is positioned on the outer wall of the circumference of the hollow cylinder, and the wall section, which is covered by the appendage  35  has access openings  36  through which the frying fat  15  can be conveyed from the cooking vessel  10  into the conduction sleeve  19  in a downwards direction, heated up there, and once heated, it can be conveyed back in an upwards direction to the frying fat  15  in the cooking vessel  10 , so as to then re-enter into the conduction sleeve  19 , having cooled down. Below the wall section of the cooking vessel  10  which is provided with access openings  36 , in the following referred to as the filter wall  37 , are located the appendage  35 , the longitudinal section of which is rectangular and the round current conduction sleeve  19 , both in contact with the filter wall  37 . With its circumference wall  10   a  and the perpendicular walls of the appendage  35 , the round current conduction sleeve  19  forms a conveyance channel  39 , which at one end (on the down-current side) is filled from the floor space  26  with heated frying fat  15 , and which at the other end (on the up-current side) it conveys it to the frying fat held in the cooking vessel  10  through access openings  36   a . During normal operation of the heating device  11 , the access openings  36   a  serve predominantly only for the conveyance of heated frying fat  15  into the frying fat  15  in the cooking vessel  10 , ie. into the drum  10 , whereas the cold or cooled down frying fat  15  enters through the access openings  36  into the inner space of the conduction sleeve  19 . In the inner space of the conduction sleeve  19  there are several heating elements  20  located on the down-current side of the filter wall  37  and formed as described in connection with the embodiment in accordance with FIGS.  1  to  3 , below which, ie. seen in the direction of the current, the conveyance device  21  is located. The conveyance device in the current channel is positioned, formed and powered in the same way as described in FIGS.  1  to  3 .  
         [0022]     The conveyance channel  39  is essentially split in two by the conduction sleeve  19 , whereby the parts  39   a ,  39   b  in the cross-section are essentially rectangular with a concave wall surface. It has been shown that a conveyance channel with this cross-section just as effectively allows heated frying fat  15  to rise as the riser pipe  27  in accordance with  FIG. 1 . The embodiments in accordance with  FIGS. 1 and 4  are also provided with devices for keeping the frying fat temperatures constant (not shown), which measure the latter, and correspondingly apply electric energy to the heating elements. These devices can also be designed so that if the deep frying appliance is set to ‘wait’, the temperature of the frying fat  15  can be lowered and raised when being loaded.