Abstract:
A conveyor oven with improved energy efficiency. The energy efficiency is achieved by providing baffles at an inlet and an outlet of the conveyor oven. The baffles are individually controlled to be closed during cooking operations except for the time required for the passage of a food product through the respective inlet and outlet. The baffles can be operated manually or by electrically driven devices such as solenoids or electric motors. A controller can be used to control the open and closed times of the baffles based on sensor inputs as well as the speed of the conveyor, a predetermined length of the oven cavity between the inlet and outlet and a size of the food product.

Description:
RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Patent Application No. 60/523,199, filed on Nov. 18, 2003, and of U.S. Provisional Patent Application No. 60/612,718, filed on Sep. 24, 2004, the entire contents of both of which are hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to a conveyor oven with an energy saving baffle mechanism and method.  
       DISCUSSION OF THE BACKGROUND ART  
       [0003]     Conveyor ovens typically transport food on a conveyor along a cooking path between an inlet and an outlet. Heat provided along the cooking path can escape the oven through the inlet and the outlet. The lost heat can seriously affect the thermal efficiency of the oven.  
         [0004]     Thus, there is a need to reduce the heat loss in a conveyor oven.  
       SUMMARY OF THE INVENTION  
       [0005]     A conveyor oven of the present invention comprises an oven cavity that has at least one opening. A conveyor is positioned to extend into the oven cavity via the opening. A source of thermal energy provides heat in the oven cavity. A baffle is located within the opening and is operable between a closed position and an open position. The heat loss from the oven cavity via the opening is reduced when the baffle is in the closed position versus when the baffle is in the open position.  
         [0006]     In the conveyor oven of the present invention, the opening is at least one selected from the group consisting of: inlet and outlet.  
         [0007]     The conveyor oven of the present invention preferably includes a frame member, wherein the baffle is operatively coupled to the frame member. In one embodiment, the frame member preferably comprises a pair of spaced apart pegs located above the opening. The baffle comprises a pair of vertical slots that mate with the pegs. The motion is a sliding motion of the baffle and pegs throughout a length of the slots.  
         [0008]     Preferably, a controller controls the baffle to be in the closed position except for a time required for a passage of a food product carried by the conveyor through the opening, thereby minimizing the heat loss. The baffle further comprises a module that comprises a drive unit that controls the movement of the baffle between an open position and a closed position. The controller controls the baffle to be in the open and closed positions based on a position of the food product relative to the opening, a speed of the conveyor and a predetermined length of the oven cavity.  
         [0009]     Preferably, the drive unit is selected from the group consisting of: a motor, linear actuator, a mechanical gear and chain drive, and a solenoid valve. Moreover, the drive unit causes the baffle to be in the open position only for the time required for a passage of a food product carried by the conveyor through the opening.  
         [0010]     Preferably, the module further comprises a sensor that senses at least one condition selected from the group consisting of: a food product, open baffle, closed baffle and any combination of open baffle and closed baffle. The module further comprises a mechanical linkage that moves the baffle between the open and closed positions.  
         [0011]     In another embodiment of the conveyor oven of the present invention, the conveyor oven further comprises a mechanical linkage, which comprises a rail, a slider and one or more links. The electrically driven device via at least one of the links moves the slider along the rail. The baffle is coupled to the slider via another one of the links so as to follow the motion of the slider.  
         [0012]     A method of the present invention controls a conveyor oven that comprises an oven cavity that includes at least one opening and a conveyor that extends through the opening. The method comprises providing thermal energy in the oven cavity and, during a cooking operation, covering the opening with a baffle when a food product is disposed within the cavity. The heat loss from the oven cavity via the opening is reduced when the baffle is in a closed position versus when the baffle is in an open position.  
         [0013]     The baffle is driven with a drive unit between an open position and a closed position in which the opening is uncovered and covered, respectively.  
         [0014]     In an alternate embodiment of the method of the present invention, the baffle is controlled to be in the open and closed positions based on a position of the food product relative to the opening, a speed of the conveyor and a predetermined length of the oven cavity. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     Other and further objects, advantages and features of the present invention will be understood by reference to the following specification in conjunction with the accompanying drawings, in which like reference characters denote like elements of structure and:  
         [0016]      FIG. 1  is a block diagram in part and an elevation view in part of one embodiment of the conveyor oven of the present invention;  
         [0017]      FIG. 2  is a perspective view of another embodiment of the conveyor oven of the present invention;  
         [0018]      FIG. 3  is a perspective view of a detail  3  of the conveyor oven of  FIG. 2 ;  
         [0019]      FIG. 4  is a perspective view of the baffle mechanism of  FIG. 3 ;  
         [0020]      FIG. 5  is a perspective view another embodiment of the conveyor oven of the present invention;  
         [0021]      FIG. 6  is a perspective view of a detail  6  of  FIG. 5 ;  
         [0022]      FIG. 7  is an end view of the baffle mechanism of the conveyor oven of  FIG. 5 ; and  
         [0023]      FIG. 8  is a front elevation view of the baffle mechanism of the conveyor oven of  FIG. 5 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0024]     Referring to  FIG. 1 , a conveyor oven  20  of the present invention comprises an oven cavity  28  with an outlet  22  and an inlet  24 . A conveyor  26  is positioned to convey food products in the direction shown by an arrow  27 , the food products entering oven cavity  28  via inlet  24  and leaving via outlet  22 . A module  32  and a module  30  are located adjacent inlet  24  and outlet  22 , respectively. In the embodiment shown in  FIG. 1 , modules  30  and  32  are mounted above conveyor  26 . A baffle  34  and a baffle  36  are mechanically coupled to modules  30  and  32 , respectively. A controller  42  is electrically coupled to modules  30  and  32 . Baffle  34  and module  30  comprise a baffle mechanism and baffle  36  and module  32  comprise a baffle mechanism.  
         [0025]     Module  30  includes a drive unit shown as a solenoid valve  37  and a proximity sensor  39 . Module  32  includes a drive unit shown as a solenoid valve  38  and a proximity sensor  40 . Controller  42  responds to signals from proximity sensors  39  and  40  to control solenoid valves  37  and  38  to raise and lower baffles  34  and  36  so as to limit the loss of thermal energy via inlet  24  and outlet  36 . Proximity sensors  39  and  40  are located to detect a food product presence on conveyor  26  outside of oven cavity  28 .  
         [0026]     A suitable source of thermal energy is provided to provide heat in oven cavity  28  for cooking the food products as they traverse oven cavity  28  on conveyor  26 . For example, a fan box  44  and one or more plenums  46  and  48  are provided in fluid communication with oven cavity  28  to circulate heated air in a path that includes fan box  44 , plenums  46  and  48  and one or more air returns (not shown). The circulating air is heated by a heater  50  that may be located in fan box  44 . Plenums  46  and  48  can be designed to provide columns of impingement air toward conveyor  26 . Alternatively, or additionally, similar plenums in fluid communication with fan box  44  and oven cavity  28  could be located below conveyor  26 . Alternatively, or additionally, a radiant heater (e.g., an infrared heater) could be disposed above and/or below conveyor  26 .  
         [0027]     Controller  42  controls the opening and closing of baffles  36  and  34  to limit thermal loss via inlet  24  and outlet  22 . That is, controller  42  opens baffle  36  only for the time required for a passage of a food product through inlet  24  to enter oven cavity  28  and opens baffle  34  for the time required for a passage of the food product through outlet  22  to leave oven cavity  28 . The arrival of a food product on conveyor  26  outside of inlet  24  is detected by proximity sensor  40 , which provides an entry signal to controller  42 . Controller  42  responds by controlling solenoid valve  38  to open or raise baffle  36 . Baffle  36  remains open until the food product is entirely within oven cavity  28 . Controller  42  then controls solenoid valve  38  to lower or close baffle  36 .  
         [0028]     Oven cavity  28  can be of any predetermined length. Modules  30  and  32  are in communication with controller  42  to provide information regarding the location of the food product on conveyor  26 . Controller  42 , based on the conveyor speed and food product size determines an entry time period that baffle  36  must remain open to allow entry of the food product via inlet  24 . Upon expiration of the entry time, controller  42  causes solenoid valve  38  to lower or close baffle  36 . Controller  42 , based on the predetermined length of oven cavity  28 , calculates the travel time of the food product inside oven cavity  28 . Upon the expiration of the travel time, controller  42  then provides a signal to solenoid valve  37  to open baffle  34  to allow the food product to leave oven cavity  28  via outlet  22 . Proximity sensor  39  detects when the food product has exited oven cavity  28  and provides a signal to controller  42 . Controller  42  responds to this signal to cause solenoid valve  37  to lower or close baffle  34 . By controlling the opening and closing of baffles  34  and  36 , the energy reduction of conveyor oven  20  is about 30% for an air impingement pizza oven as compared to a continuous full open condition of inlet  24  and outlet  22 .  
         [0029]     Referring to  FIGS. 2-4 , an alternate embodiment of the conveyor oven of the present invention comprises a baffle mechanism that includes a baffle  60  disposed at inlet  24  of conveyor oven  20 . A duplicate baffle mechanism (not shown) is located on the opposite end or outlet of conveyor oven  20 . Referring to  FIGS. 3 and 4 , baffle  60  comprises an elongated plate that has a cutout  66  located near one vertical edge and another cutout  68  located near an opposite vertical edge. The shape of baffle  60  and cutouts  66  and  68  are arranged to provide for raising and lowering baffle  60  manually across inlet  24  of conveyor oven  20 , immediately above conveyor  26 . To this end, a frame member  62  of conveyor oven  20  comprises a pair of pegs  66  that are spaced apart horizontally so as to mate with cutouts  66  and  68  of baffle  60 .  
         [0030]     Cutouts  66  and  68  each include a vertical slot  70  that is connected to a plurality of notches  72 ,  74  and  77  that are spaced vertically along slot  70 . The arrangement of slot  70  and notches  72 ,  74  and  76  provides for movement of baffle  60  without a need to remove it completely from frame member  62 . This eliminates any need for tightly fastening baffle  60  to frame member  62 . Baffle  60  can be moved easily vertically along slot  70  and horizontally into and out of notches  72 ,  74  or  76  with common tools or by hand, with hand protection for the high heat. When pegs  64  are in the top most notches  72 , baffle  60  is in a lowered or closed position, which is the energy saving position. To shift baffle  60  to a fully raised or opened position, a lip  78  of baffle  60  can be grasped to manually move baffle  60 . Baffle  60  is first raised and then slid horizontally so that pegs  64  are in slots  70 . Baffle  60  is then raised by sliding vertically in slots  70  until notches  76  reach the level of pegs  64 . Baffle  60  is then moved horizontally until pegs  64  are in notches  76 . When in this position, food products can freely enter oven cavity  28 . To return to the energy efficient position, baffle  60  is moved horizontally until pegs  64  are in slots  70  and then slid vertically downwardly until notches  72  reach the level of pegs  64 . Baffle  60  is then moved horizontally until pegs  64  are in notches  72 . Intermediate notches  74  allow baffle  60  to be partially open for a food product having a lower height. It will be apparent to those skilled in the art that additional intermediate notches could be provided to accommodate a plurality of different food product heights.  
         [0031]     Referring to  FIGS. 5-8 , another alternate embodiment of the baffle mechanism of the present invention comprises a baffle mechanism  90  disposed at inlet  24  of conveyor oven  20 . A duplicate baffle mechanism (not shown) is located at the opposite end or outlet of conveyor oven  20 . Baffle mechanism  90  includes a module  92  and a baffle  94 . Module  92  is mechanically couple to baffle  94  and is operative to move baffle  94  between a lowered or closed position and an upper or opened position. Module  92  comprises a drive unit shown as an electric motor  100  that is operative to drive a mechanical linkage that raises and lowers baffle  94 . The mechanical linkage includes a link  102 , a link  104  and a drive arm  106  that are configured for motion up and down a rail  96 . A slider is positioned to slide up and down in rail  96  and is coupled to drive arm  106  and to link  104  via link  102 . Drive arm  106  is also fastened to baffle  94 . Motor  100  is coupled to link  104  via a bushing  108 . As motor  100  drives the linkage of links  104  and  102 , drive arm  106  and slider  98  to move up and down rail  96  carrying baffle  94  between a closed position and an open position. A magnet  110  is used in combination with a hall-effect sensor (not shown) to signal a fully up or a fully down position of baffle  94 , the signal being used to control motor  100 .  
         [0032]     Motor  100  may be activated in a variety of ways. A simple switch (not shown) can be used to turn motor  100  on and off to raise or lower baffle  94 . A more complex method using one or more microprocessors can have sensors or logic based algorithms to derive the energy savings without human intervention. This methodology would provide the optimum energy savings, as the system would not require an individual interpretation of events to determine the most efficient times to energize the system.  
         [0033]     The conveyor oven of the present invention improves the thermal efficiency by providing an inlet baffle and an outlet baffle that are each controlled to open and close based on the location of food on the conveyor. A process controller responds to proximity sensors  39  and  40  to calculate the opening and closing times of the baffles based on the speed of the conveyor.  
         [0034]     The present invention having been thus described with particular reference to the preferred forms thereof, it will be obvious that various changes and modifications may be made therein without departing from the spirit and scope of the present invention as defined in the appended claims.