Abstract:
A convection recirculating food product fryer with a fry tank with and inlet tube connected to a heat exchanger and an outlet connected to a magnetic pump with an outlet tube to the heat exchanger, the pump having a driving magnet assembly housing an impeller and a driven magnet, with a ceramic shaft extending through the impeller about which the impeller rotates when pumping oil; an electric motor magnetically coupled to the magnetic pump; a burner to heat the oil in the heat exchanger; a controller to control the ignition and running of the burner.

Description:
TECHNICAL FIELD 
       [0001]    The present invention is generally related to a convection frying apparatus for cooking foods within a recirculating bath of cooking liquid. 
       BACKGROUND OF THE INVENTION 
       [0002]    Although there are many ways to prepare food for consumption, one common method of preparing foods is to cook the food by frying. Additionally, one method of frying food is to “deep fry” the food by placing the uncooked food in a quantity of cooking liquid. In most deep frying situations, the cooking liquid typically comprises a cooking oil, such as vegetable oil or animal fat. The food product is immersed in the cooking oil. The cooking oil is typically at a high temperature, such as above 350 degrees Fahrenheit. 
         [0003]    Devices for deep frying are common in commercial food preparation environments. They are also becoming increasingly common in the home environment. Although a commercial frying apparatus and a home frying apparatus may he constructed on different scales, these two types of fryers have some of the same basic features. 
         [0004]    The primary feature of a typical fryer, whether commercial or residential, is a cooking tank housing the heated bath of cooking oil. The cooking tank is usually designed so that it may receive a metal basket into the tank. Food is placed in the metal basket and lowered into the cooking oil so that the food is at least partially submersed in the oil. 
         [0005]    A heating device is typically used to maintain the oil in the tank at a substantially constant temperature. This heating device usually comprises a gas burner placed below the tank. 
         [0006]    The typical fryers used in commercial and residential settings do not remove the oil from the tank during operation. The cooking oil simply remains in the tank and the temperature of the oil is regulated by heating the oil while the oil remains in the tank. In contrast, a recirculating fryer removes oil from the tank, adjusts the heat energy in the oil, and then returns the oil to the tank. 
         [0007]    There have been previous attempts to develop a commercial recirculating fryer. However, these recirculating fryer designs have all suffered from a number of limitations. For example, some recirculating fryer designs exhibited problems with leaking seals in the pump. The pump seals became worn with use and began to leak. Other designs, while not necessarily having a problem with leaking seals, experienced failure of the pump bearings. This was usually a result of the arrangement of the pump. In general, the prior recirculating fryers were far too expensive to maintain in order to be feasible for commercial use. 
         [0008]    Thus, a heretofore unaddressed need exists in the industry to develop a convection recirculating fryer that is efficient, cost-effective, and having reasonable maintenance costs. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0009]    Many aspects of the invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
           [0010]      FIG. 1  is a side view of the convection recirculating fryer. 
           [0011]      FIG. 1A  is section view of the gas injectors of the convection recirculating fryer of  FIG. 1 . 
           [0012]      FIG. 2A  is a top view of the convection recirculating fryer of  FIG. 1   
           [0013]      FIG. 2B  is a front view of the convection recirculating fryer of  FIG. 1   
           [0014]      FIG. 3  is cut away view of the magnetic pump of the convection recirculating fryer of  FIG. 1 . 
           [0015]      FIG. 4  is a cut away side view of a magnetic pump to be used in the convection recirculating fryer of  FIG. 1 . 
           [0016]      FIG. 5  is an exploded part view of a magnetic pump used in the convection recirculating fryer of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION  
       [0017]    A convection recirculating fryer of one exemplary embodiment comprises, generally, a fryer housing forming a tank, and encasing a pump and a heat exchanger. Although all of these elements are not required by the invention disclosed herein, these three elements are the basic components of an exemplary embodiment of a convection recirculating fryer. 
         [0000]    
       
         
               
             
               
               
             
           
               
                   
               
               
                 PARTS LIST 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 10. Convection fryer 
               
               
                   
                 11. Free standing housing 
               
               
                   
                 13. Fry tank 
               
               
                   
                 16. Oil inlet orifice 
               
               
                   
                 17. Oil outlet orifice 
               
               
                   
                 18. Filter screen 
               
               
                   
                 19. Bottom of tank 
               
               
                   
                 20. Oil dispersement pipe 
               
               
                   
                 21. Magnetic pump 
               
               
                   
                 22. Pump inlet line 
               
               
                   
                 26. Motor 
               
               
                   
                 27. Motor casing 
               
               
                   
                 28. Motor shaft 
               
               
                   
                 29. Driving magnet assembly 
               
               
                   
                 31. Impeller housing 
               
               
                   
                 32. Driven magnet 
               
               
                   
                 34. Impeller 
               
               
                   
                 35. Pump housing 
               
               
                   
                 46. Hot oil supply line 
               
               
                   
                 50. Blower 
               
               
                   
                 52. Fuel injector tube 
               
               
                   
                 54. Glow plug with flame sensor 
               
               
                   
                 56. A-D Fuel injectors 
               
               
                   
                 58. Gas Manifold 
               
               
                   
                 60. Perforated burner sleeve 
               
               
                   
                 62. Control 
               
               
                   
                 64. Ceramic pump shaft 
               
               
                   
                 66. Magnet 
               
               
                   
                 67. Seal 
               
               
                   
                 68. Filter pump 
               
               
                   
                   
               
             
          
         
       
     
         [0018]    An exemplary embodiment of a convection recirculating fryer  10  is depicted in  FIG. 1 .  FIG. 1  is not to scale and is merely presented to provide a general understanding of the components of the convection recirculating fryer  10 . The arrangement of the components of the convection recirculating fryer  10 , as discussed below, is only one exemplary arrangement. 
         [0019]      FIG. 1  depicts the convection recirculating fryer  10  having a housing  11 . The housing  11  of the fryer  10  can be comprised of a metal material. The housing  11  of the preferred embodiment  10  is a free-standing housing  11 .  FIG. 2A  is a top view of the convection recirculating fryer  10 . Alternatively, the housing  11  of the convection recirculating fryer  10  could comprise a smaller, counter-top model, such as for home use. The principles of the invention described herein are not changed by scaling the fryer  10  up or down in size. 
         [0020]    The fryer  10  also has a fry tank  13 . See  FIG. 1 . The fry tank  13  of the preferred embodiment  10  is adapted to receive and hold cooking liquid (not depicted), such as cooking oil (e.g. animal fat, shortening, vegetable-oil, or the like). The tank  13  of the preferred embodiment  10  has an open top, an oil inlet orifice  16  and an oil outlet orifice  17 . Basically, the preferred tank  13  resembles a deep tub, or retangularly-cubic bucket. 
         [0021]    The tank  13  is also preferably designed to receive a basket (not depicted). The basket typically houses a food product to be cooked in the cooking liquid. Other implementations of placing food to be cooked in the cooking liquid are, of course, possible. The present invention is not limited to any particular method and apparatus for exposing food products to a cooking liquid. 
         [0022]    The tank  13  of the preferred convection recirculating fryer  10  may also comprise a filter apparatus  18 , as depicted in  FIG. 3 . As depicted in  FIG. 3 , the filter apparatus is a screen  18  positioned along the bottom  19  of the tank  13 . This apparatus maybe of any appropriate type; however, the preferred filtering apparatus is an active filtering device that pulls cooking liquid into the apparatus  18 , removes foreign matter, and then deposits the cooking liquid back into the main compartment of the tank  13 . The preferred filtering apparatus  18  is comprised of a frame that supports the filter material, or “filter sock,” and a gear pump. The filter sock is placed over the frame; which has a pipe connection at a bottom portion. The gear pump draws the cooking liquid from the tank  13 , through the filter sock, through an oil dispersement pipe  20 , a filter pump  68 , and back into the tank  13 . Contaminants in the cooking liquid are deposited on the filter sock where they become imbedded and remain there. 
         [0023]    The fryer  10  also employs a passive filter (not depicted) at the oil outlet orifice  17  of the tank  13 . The convection recirculating fryer  10  includes a magnetic pump  21  that draws cooking liquid from the tank  13 . For this reason, a passive filtering apparatus could include a screen-type assembly releasably mounted in the cooking tank  13 , and substantially covering the oil outlet orifice  17  of the cooking tank  13 , for prohibiting larger foreign matter from entering into the magnetic pump  21  and disturbing heat exchanger  41 . 
         [0024]    As noted above, the tank  13  has an oil outlet orifice  17 . This orifice  17  is preferably near a lower portion of the tank  13 . This orifice  17  of the tank  13  is connected to pump inlet line  22 . This inlet line  22  is designed to carry the cooking liquid to an inlet of the pump  21 . 
         [0025]    The magnetic pump  21  is depicted in  FIG. 4 . The magnetic pump  21  comprises a motor  26  in a motor casing  27 . A motor shaft  28  to be driven by the motor  26  protrudes from the motor casing  27  and is attached to a driving magnet assembly  29  comprising a driving magnet. The driving magnet assembly  29  of the preferred embodiment is cylindrical in shape. A magnet such as the driving magnet  29  can be manufactured from a Samarium Cobalt material which will withstand the high temperature of the cooking oil. 
         [0026]    Inside the cylindrical driving magnet assembly  29 , with a plurality of magnets  66 , is an impeller magnet housing, or casing  31 . The impeller magnet housing  31  of the magnetic pump  21  is hermetically sealed so that any fluid in the impeller magnet housing  31  will not escape to an area exterior to the impeller magnet housing  31 . 
         [0027]    Inside the impeller magnet housing  31  is a driving magnet  32  and an impeller  34 . As depicted, the driven magnet  32  and the impeller  34  may be a single unit. In an alternative embodiment, the impeller  34  and the driven magnet  32  may be separate elements connected by a shaft. As is understood by one with ordinary skill in the art, the impeller  34  is the actual device that moves fluid through the magnetic pump  21 . 
         [0028]    The impeller magnet housing  31  is preferably connected to a pump housing  35 . The pump housing  35 , in combination with the impeller magnet housing  31 , encases the impeller  34 . The pump housing  35  has a pump inlet  36  and a pump outlet  37 . The cooking liquid is drawn from the tank  13 , though the pump inlet line  22 , into pump inlet  36  and into the pump housing  35  by the action of the impeller  34 . The impeller  34  also, through its motion, ejects the cooking liquid from the pump housing  35  of the magnetic pump  21 . The cooking liquid is ejected though the pump outlet  37  and into pump outlet line  38 . 
         [0029]    It is essential that the shaft  64  of the pump about which the impeller  34  turns be constructed of ceramic material to withstand the heat of the oil. A seal  67  prevents the leakage of oil from the pump. 
         [0030]    The preferred motor  26  of the magnetic pump  21  has approximately 1.0 horsepower and will perform at approximately 3450 revolutions per minute. Of course, the motor  26  may be sized differently depending on the particular design of the convection reciprocating fryer  10 . One having ordinary skill in the art will readily be able to size the motor  26  for a particular fryer. 
         [0031]      FIG. 5  depicts an exploded part diagram of the magnetic pump to be used with the present preferred embodiment.  FIG. 5  depicts that pump  21  comprises a motor  26  and a housing  27 , a driving magnet assembly  29 , an impeller magnet housing  31 , an impeller  34 , with driven magnets  32  and a pump housing  35 . Of course, this is only one possible magnetic pump that may be used with the present invention. 
         [0032]    As depicted in  FIG. 2A , the magnetic pump  21  is preferably situated vertically within the fryer housing  11  in order to minimize the possibility of a steam lock in the pump, which would prevent the circulation of the oil through the fryer. Although preferred in the exemplary embodiment  10 , the pump is not required to be situated vertically. Also, the pump outlet  37  of the pump housing  35  is connected by the pump outlet line  38  to a heat exchanger  41 . 
         [0033]    The preferred heat exchanger  41  comprises a series of tubing (not depicted) with a heat source near, or even within, the tubing. In the preferred embodiment  10 , the heat exchanger  41  comprises a cylindrical heat exchanger as is conventionally known in the art. The heat exchanger has a heat exchanger exhaust  42 . The heat exchanger exhaust  42  of the heat exchanger  41  is in fluid communication with the pump outlet  37  of the pump  21  via the pump outlet line  38 . 
         [0034]    The heating element of the heat exchanger  41  preferably comprises a burner positioned along the axis of the heat exchanger  41 . The heating element could be electric or gas powered, for example. It is preferred that the heating element comprise an LP or natural gas powered burner. The heating element, of course, could also be equipped with a blower  50  in order to more evenly distribute heat throughout the heat exchanger  41 . 
         [0035]    Gas can be distributed through a gas manifold  58  as shown in  FIG. 1A  to a number of fuel injectors  56 A-D to a fuel injector tube  52 . Several fuel injectors are preferred for the even burning of the gas. It has been found that four injectors are preferred. The gas is ignited by a glow plug with a flame sensor  54  to make sure the gas is turned off if it does not ignite in a specified time. The flame extends from the fuel injector tube  52  into the heat exchanger  41  through a perforated burner sleeve  60 . The convection recirculating fryer  10  is controlled by a controller  60 . 
         [0036]    The heat exchanger  41  is designed such that the cooking oil travels through heat exchanger tubing within the heat exchanger  41 . The internal heat exchanger tubing is configured to permit the passage of the cooking oil back and forth across the burner within the heat exchanger. The internal tubing also includes fins for facilitating the absorption of heat from the burner. 
         [0037]    The heated cooking oil is ejected from the heat exchanger  41  at the hot oil supply line  46 . Preferably, the cooking oil is moved from the heat exchanger  41  at a constant predetermined temperature (which is usually around 350 degrees Fahrenheit). A control system (not depicted) operates in conjunction with a temperature sensor (not depicted) mounted on the outside of the hot oil supply line  46  to ensure that the cooking oil outlet from the heat exchanger  41  remains at the predetermined temperature. Obviously, if the temperate of the cooking oil drops below the target value, or range, the heating element is instructed by the control system to emit more heat energy into the cooking oil. Conversely, if the temperature of the cooking oil increases above the target value, or range, the heating element is caused to emit less heat energy. 
         [0038]    The hot oil supply line  46  of the heat exchanger  41  is connected to the oil inlet orifice  16  of the tank  13 . Thus, the cooking oil completes its journey from the tank  13 , to the pump  21 , to heat exchanger  41 , end back to the tank  13 . As noted above, the magnetic pump  21  of the fryer  10  is the device that actually causes the cooking oil to flow from the tank  13 , to the pump  21 , to heat exchanger  41 , and back to the tank  13 . The appropriate rate of flow of the oil can be determined by one of ordinary skill in the art and is not important to the present invention. 
         [0039]    It should be emphasized that the above-described embodiments of the present invention, particularly, any “preferred” embodiments, are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the invention. Many variations and modifications may be made to the above-described embodiment(s) of the invention without departing substantially from the spirit and principles of the invention. All such modifications and variations are intended to be included herein within the scope of this disclosure.