Abstract:
An oven includes a conveying interior for moving produce through the oven and a gas fired heat source for cooking the produce conveyed through the oven. The conveying interior preferably comprises a rotating drum with a conveying spiral extending inwardly from an inner wall of the rotating drum. The rotating drum may further be sloped downward to facilitate progress of the produce through the oven, and the time spent in the oven may be controlled by controlling the rotating rate of the drum. The gas fired heat source may comprise a thermostatically controlled burner residing under the drum.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to ovens and in particular to a gas fired continuous feed oven. 
   Salsa has become a very popular garnishment for a variety of Mexican food and various corn chips. In particular, many salsa users prefer fire roasted salsas. One of the most important steps in producing a high quality fire roasted salsa is cooking the salsa ingredients, and in a production environment, the salsa ingredients are preferably cooked in a continuous feed oven (i.e., an oven in which the produce being cooked is continuously fed into the oven and is cooked as it moves through the oven.) Known continuous feed ovens use steam to cook the salsa ingredients, but the steam cooking does not provide the desired characteristics in the cooked salsa ingredients. 
   There is thus a need for a gas fired continuous feed oven suitable for cooking salsa ingredients. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention addresses the above and other needs by providing an oven which includes a conveying interior for moving produce through the oven and a gas fired heat source for cooking the produce conveyed through the oven. The conveying interior preferably comprises a rotating drum with a conveying spiral extending inwardly from an inner wall of the rotating drum. The rotating drum may further be sloped downward to facilitate progress of the produce through the oven, and the time spent in the oven may be controlled by controlling the rotating rate of the drum. The gas fired heat source may comprise a thermostatically controlled burner residing under the drum. 
   In accordance with one aspect of the invention, there is provided a continuous feed oven including an oven housing and a rotating drum inside the oven housing. The rotating drum has a drum entrance and a drum exit and is sloped downward from the drum entrance to the drum exit at between approximately two degrees and approximately five degrees. A conveying spiral resides inside the rotating drum and advances produce through the rotating drum. The conveying spiral is fixedly attached to an inner wall of the rotating drum, an electric motor rotates the drum, and a mechanical drive rotationally connects the electric motor to the drum. A gas fired heat source resides inside the housing and produces a flame under the rotating drum and includes a blower for mixing air with gas to produce the flame under the rotating drum. A thermostat controls turning the gas fired heat source on and off to control a cooking temperature. 
   In accordance with another aspect of the invention, there is provided a method for cooking fire roasted salsa ingredients. The method includes feeding the salsa ingredients into a drum entrance of a rotating drum of a gas fire heated continuous feed oven, rotating the rotating drum to advance the salsa ingredients through the rotating drum, burning gas to cook the salsa ingredients in the rotating drum, and emptying the cooked salsa ingredients from the rotating drum. The gas fire may be controlled to generate a lower temperature between approximately 300 degrees Fahrenheit and approximately 400 degrees Fahrenheit, and an upper temperature between approximately 400 degrees Fahrenheit and approximately 410 degrees Fahrenheit. The rotating drum may be rotated at approximately one revolution per minute. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
     The above and other aspects, features and advantages of the present invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein: 
       FIG. 1A  is a front corner perspective view of a continuous feed oven according to the present invention. 
       FIG. 1B  is a rear corner perspective view of the continuous feed oven according to the present invention. 
       FIG. 2A  is a front view of the continuous feed oven. 
       FIG. 2B  is a side view of the continuous feed oven. 
       FIG. 2C  is a rear view of the continuous feed oven. 
       FIG. 3  is a cross-sectional view of the continuous feed oven taken along line  3 - 3  of  FIG. 2A . 
       FIG. 4  is a side view of a rotating drum according to the present invention of the continuous feed oven. 
       FIG. 5  is a cross-sectional view of the rotating drum taken along line  5 - 5  of  FIG. 4 . 
       FIG. 6  is a method for cooking using the continuous feed oven of the present invention. 
   

   Corresponding reference characters indicate corresponding components throughout the several views of the drawings. 
   DETAILED DESCRIPTION OF THE INVENTION 
   The following description is of the best mode presently contemplated for carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing one or more preferred embodiments of the invention. The scope of the invention should be determined with reference to the claims. 
   A front corner perspective view of a continuous feed oven  10  according to the present invention is shown in  FIG. 1A  and a rear corner perspective view of the continuous feed oven  10  according to the present invention is shown in  FIG. 1B . The continuous feed oven  10  is advantageous in a production environment when a large quantity of material (e.g., produce) must be cooked or roasted. The oven  10  provides a continuous flow of cooked or roasted material. The continuous feed oven  10  includes a housing (or oven) entrance  18  in an oven housing  12 , wherethrough produce may enter the oven  10  for cooking or roasting, and a housing (or oven) exit  19  wherethrough cooked produce may escape the oven  10  after cooking. The housing entrance  18  remains at least partially open during cooking to allow raw produce to enter the oven while earlier entering produce is being cooked, and the housing exit  19  remains at least partially open during cooking to allow cooked produce to escape the oven  10  while later entering produce is being cooked. Thus, the oven  10  is a continuous feed (or flow) oven. Vertical ducts  13  allow the oven to be vented. 
   A moveable entrance door  14  partially covers the entrance  18  to reduce the escape of heat from the oven  10 , while allowing raw produce to be fed into the oven entrance  18  while earlier produce is being cooked within the oven  10 . The door  14  preferably covers approximately half of the oven entrance  18  and the door  14  may be pivotally mounted using a first hinge  16   a . An exit door  22  is moveably attached to the housing  12  and may be positioned to substantially cover the exit  19 , leaving a small opening at the bottom of the exit  19  for cooked produce to exit the oven  10  while later produce is being cooked within the oven  10 . The exit door  22  is preferably attached to a second hinge  16   b  by an arm  24  and the exit  19  is preferably lower than the entrance  18 . A thermostatic control  20  resides on a side of the oven  10  for adjusting the cooking temperature inside the oven  10 . 
   A front view of the continuous feed oven  10  is shown in  FIG. 2A , a side view of the oven  10  in  FIG. 2B , and a rear view of the oven  10  in  FIG. 2C . The entrance door  14  is shown closed over the entrance  18  (see  FIG. 1A ), but may pivot about the hinge  16   a  as shown by arc  26  to allow access to an interior of the oven  10  for cleaning and other maintenance. The exit door  22  is shown closed over the exit  19  (see  FIG. 1B ) but may pivot about the hinge  16   b  along arc  28  to allow access to the interior of the oven  10  for cleaning and other maintenance. 
   A cross-sectional view of the oven  10  taken along line  3 - 3  of  FIG. 2A  is shown in  FIG. 3 . A rotating drum  30  resides inside the oven  10 . The drum  30  both helps convey produce through the oven  10 , and tumbles the produce to improve cooking of the produce. The drum  30  is rotationally supported at each end by rollers  33   a  and  33   b , and rotated by an electric motor  34 . The motor  34  is mechanically connected to the drum  30  by a mechanical connection comprising an intermediate gear  35  and a drum gear  36 . The drum gear  36  may be a chain (e.g., a motorcycle type chain) welded or otherwise attached to the outside of the drum. The motor  34  is preferably a variable speed motor to allow control of the rotational speed of the drum  30 . 
   The drum  30  preferably includes a continuous conveying spiral  32  for urging the produce through the oven  10 . Consecutive 360 degree loops of the conveying spiral  32  are preferably spaced a distance D apart, wherein the distance D is preferably between approximately six inches and approximately 14 inches, and more preferably approximately ten inches. The drum  30  has a drum entrance  30   a  and a drum exit  30   b  (see  FIG. 4 ). The drum entrance is substantially aligned with the housing entrance  18 , and the drum exit  30   b  is substantially aligned with the housing exit  19  to allow the entrance and exit of produce into and from the oven  10 . Produce serially enters the drum  30  through the entrances  18  and  30   a , and serially exits the drum  30  through the exits  30   b  and  19 . An entry mouth  18   a , preferably comprising a lower half of the entrance  18  (i.e., below the bottom edge of the closed door  14 ), remains open during operation of the oven  10  to allow raw produce to enter the oven  10  while the oven  10  is cooking earlier entering produce. An exit mouth  19   a , preferably a gap G at the bottom of the exit  19 , remains open during operation of the oven  10  to allow cooked produce to exit the oven  10  while the oven  10  is cooking later entering produce. The gap preferably comprises a small gap between the drum exit  30   b  (see  FIG. 4 ) and the bottom of the closed door  22 . 
   The drum  30  has a length L (see  FIG. 4 ) of preferably between approximately six feet and approximately 14 feet, and more preferably approximately ten feet and the drum  30  is preferably sloped downward from the drum entrance  30   a  to the drum exit  30   b . The lowest point of drum entrance  30   a  is more preferably at a height H 1  of approximately 45 inches and the lowest point of the drum exit  30   b  is more preferably at a height H 2  of approximately 38 inches. Further, the drum exit  30   b  is preferably between approximately four inches and approximately 12 inches lower than the drum entrance  30   a , and more preferably, the drum exit  30   b  approximately seven inches lower than the drum entrance  30   a . For other length rotating drums, the slope is preferably between approximately two degrees and approximately five degrees, and is more preferably approximately 3.3 degrees. 
   Heat is provided to the oven  10  using a gas fired heat source. A gas line  40  provides gas to a blower  38  which mixes the gas with air to produce a gas and air mixture. The air and gas mixture is carried by a pipe  42  to a burner  44  approximately centered under the drum  30  and running substantially the length of the drum  30 . The burner  44  is preferably a single pipe-like burner centered under the drum  30 . Flames  46  from the burner  44  heat the drum  30  to cook produce in the drum  30 . The burner  44  preferably provides approximately 600,000 BTUs of heat to the oven  10 . 
   The heat source is controlled by the thermostat  20 , and the thermostat measures the oven temperature using a heat probe  48 . The heat probe  48  preferably is attached to the entrance door  14  and intrudes into the oven  10 . The thermostat  20  preferably controls oven temperature by turning the burner on when the measured temperature is below a lower temperature and turning the burner off when the measured temperature is above an upper temperature. 
   A side view of the rotating drum  30  is shown in  FIG. 4 . The drum  30  has a length L of preferably between approximately six feet and approximately fourteen feet, and more preferably approximately ten feet. A cross-sectional view of the drum  30  taken along line  5 - 5  of  FIG. 4  is shown in  FIG. 5 . The drum  30  has a diameter D 2  which is preferably between approximately 24 inches and approximately 36 inches, and is more preferably approximately 28 inches. The conveying spiral  32  has an inside diameter D 1  which is preferably between approximately twelve inches and approximately 30 inches, and more preferably approximately 20 inches. Alternatively, the conveying spiral  32  preferably extends radially inwardly from the drum  30  between approximately three inches and approximately six inches, and more preferably approximately four inches. The conveying spiral  32  is preferably continuous and is fixedly attached to the plain cylindrical interior surface  30   c  of the drum  30  along an outside edge  32   a  of the conveying spiral  32 . The drum  30  and the conveying spiral  32  are preferably constructed from stainless steel. 
   A method according to the present invention for cooking using the continuous feed oven  10  is described in  FIG. 6 . The method includes feeding produce into a drum entrance of a rotating drum of a gas fire heated continuous feed oven at step  60 , rotating the rotating drum to advance the produce through the rotating drum at step  62 , burning gas to cook the produce in the rotating drum at step  64 , heating the produce to between approximately 300 degrees Fahrenheit and approximately 410 degrees Fahrenheit at step  68 , and emptying the cooked produce from the rotating drum at step  70 . The produce is preferably salsa ingredients, and more preferably at least one of tomatillos, jalapenos, chiles, and garlic. The method may further include rotating the drum at approximately one revolution per minute. The produce is preferably washed before cooking, and chilled after cooking. 
   While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.