Conveyor oven with modulated gas flow

#This invention relates to conveyor ovens having reduced fuel consumption and quieter operation, and more particularly to such ovens having a modulated gas flow.

#Prior art conveyor ovens are shown in U.S. Pat. Nos. 4,964,392 and 5,277,105 owned by the assignee of this invention and in the references cited on the cover pages of these patents. These and other similar patents may be consulted in order to learn details of how conveyor ovens are constructed and operate. Often—but not always—this type of oven is used to cook or bake pizzas, bread, or the like.

#Conveyor ovens are devices for automatically baking or cooking food products over timed periods. Normally, they have a conveyor belt which travels through an elongated oven cavity having open ends and at a speed which times the exposure of the food product to the heat of the oven. A food product, such as a pizza, for example, is placed on one end of the conveyor at the entry to the oven cavity and delivered from the oven at the opposite end of the cavity. The heat in the oven and the speed of the conveyor are coordinated so that the food product is fully and correctly cooked or baked by the time when the conveyor delivers it at the exit end.

#The invention will be better understood from the following specification taken with the accompanying drawings, in which:

#FIG. 1A is a perspective view which shows a plurality of ovens stacked one upon the other in order to increase baking capacity without increasing the oven footprint;

#FIG. 1B is a perspective view of a hot air delivery finger being removed from the oven cavity;

#FIG. 1A is a perspective view of four conveyor ovens 20a-20d each of which receives a conveyor 21 extending from an input end 21a through a cavity to an output end 21b of the oven. The motor for driving the conveyor is in the housing 22. FIG. 2 shows equipment which is seen if a side panel (not shown) has been removed from the housing of the oven in order to show the parts 26 which are material to the invention.

#In greater detail, FIG. 1A shows a plurality of the ovens 20a-20b (sometimes called “decks”) stacked one on the other to increase the baking capacity without increasing the footprint dimensions. FIG. 1B is a perspective view of a person removing an upper hot air delivery finger 24 from an oven by sliding it in direction A along side rail tracks. FIG. 1C is a perspective view of the finger 24 construction where two perforated plates 24a, 24b direct streams of hot air downwardly and onto the upper surface of a food product. Lower fingers 25 direct hot air upwardly through perforated plate 25b and onto the lower surface of a food product. The hot air recycles by flowing from a plenum 10, through the fingers 24, 25 and returning by upper and lower air return flow paths 12, 14 between the top and bottom fingers 24, 25 to the plenum 10.

#The material parts 26 are shown in greater detail in FIGS. 2 and 4. Natural or propane gas is fed from a source to the burner via a line 28 and a modulating valve 30 under the control of a signal conditioner 31 and a temperature controller 32. Both the preferred modulating valve 30 and signal conditioner 31 are products of the Maxitrol Company and are sold under the trademark “Selectra”. The Maxitrol Company has a business address at 23555 Telegraph Rd (P.O. Box 2230), Southfield, Mich., U.S.A. 48037-2230.