Changing tastes as well as product differentiation has created a demand for certain foods that require baking at high temperatures for relatively short periods of time. Examples of these types of foods include flat breads and pita breads. A problem with high temperature ovens that can cook flat bread and pita bread is that their high temperatures require the oven walls to be heavily insulated in order to reduce burn risk. Even with insulation, conveyor-type ovens, which have interior temperatures of 900 degrees Fahrenheit or more have exterior surface temperatures hot enough to burn human skin. A cooking apparatus that is compact enough to be used on a countertop and which has a reduced exterior surface temperature would be an improvement over the prior art.
In order to cook flat bread, pita bread and pizza, the oven's interior temperatures are quite high, i.e., at or above about 900 degrees Fahrenheit. Exterior surfaces of the oven are kept below a temperature at which human skin will burn, i.e., about 140 degrees Fahrenheit, by a unique air cooling system that cools exterior panels using circulating room air.
The oven, which is referred to herein as a cooking apparatus 100, is comprised of a parallelepiped-shaped shell structure 102 which envelopes or covers a parallelepiped-shaped oven cabinet, not visible in
Part of a metal conveyor 120 extends from a rectangular opening 122 in the left side panel 104. Foods to be cooked are placed onto the portion of the conveyor 120 that extends from the opening 122 in the left side panel 104. The conveyor's rotation carries food items on the conveyor through the first opening 122 and into the oven cabinet 300. Inside the cabinet 300, foods on the conveyor 120 pass by infrared-emitted heaters mounted above and below the conveyor and which irradiate the top and bottom of the food items with high intensity infrared energy. The conveyor 120 drops food items out of a second opening 128 in the right side panel 106.
The conveyor 120 is comprised of a metal mesh belt, which rotates around mating metal sprockets. An adjustable combination food-crumb-collector/IR-heat shield 124 extends outwardly from the left end 104 from the opening 102 and under the portion of the conveyor 120 that extends from the first opening 122. The shield 124 is not fixed in place but is instead adjustable such that the distance that it extends from the first opening 122 can be changed simply by sliding the shield inwardly or outwardly from the first opening 122. The adjustable shield 124 collects food particles that drop from food items on the conveyor 120 but more importantly, the heat shield 124 intercepts IR that is emitted from heaters inside the oven 300 that would otherwise heat surfaces outside the oven 100. It also intercepts IR emitted from the first opening 122 that can “seen.”
In the preferred embodiment, the shell structure 102 partially covers the parallelepiped-shaped oven cabinet 300. The shell structure 102 is comprised of a stainless steel top panel 112 that extends over/covers a top panel 320 of the oven cabinet 300. A stainless steel front side panel 108 and a stainless steel rear side panel 110 cover a corresponding front side wall 224 and a rear side wall 228 of the oven cabinet 300.
The shell structure panels 108, 110 and 112 are configured to stand off from, i.e., be held away from, oven cabinet surfaces by a relatively small separation distance. The separation distance between the off-standing shell structure panels and the exterior surfaces of the oven cabinet 300 define air ducts that carry air over the oven cabinet exterior surfaces removing heat from the oven cabinet surfaces, which would otherwise be hot enough to severely burn human skin. Additional duct layers and air diverters described below direct air through the shell structure such that when the temperature inside the oven cabinet is as high as nine hundred degrees Fahrenheit, exterior surfaces of the conveyor toaster 100 are at or below a temperature at which human skin will burn, i.e., below about one-hundred forty degrees Fahrenheit.
In the preferred embodiment, the stand off distance of the shell structure panels from the oven cabinet surfaces is between about one-half inch and about one inch. Alternate spacings are used in alternate embodiments but in any case, the spacing, which corresponds to the air duct height, is great enough to carry a volume of air sufficient to keep exterior surfaces of the oven 100 below a temperature at which human skin will burn.
Still referring to
Infrared energy is provided to the oven interior by several elongated, rod-shaped and electrically-resistive heating elements 133. When an electric current flows through the heating elements 133, they emit IR, as known in the art. The heating elements 133 are attached to the interior surfaces of the oven cabinet 300 above and below the conveyor. They are configured to emit IR toward the conveyor 120 from above and below the conveyor 120.
IR heating elements 133 are preferably used with infrared reflectors 130. In the preferred embodiment, the IR reflectors 130 have a shape reminiscent of a rain gutter and have a substantially U-shaped cross section. The IR reflectors 130 capture at least some of the IR that is emitted away from the conveyor by the heating elements 133 and, re-direct the IR back toward the conveyor 120. One of the gutter-shaped reflectors 130 can be seen in
The infrared reflectors 130 behind and in proximity to the heating elements 133 increase the amount of infrared energy that is directed to a food product from the infrared heaters. However, those of ordinary skill in the art will recognize that at least some of the infrared energy emitted from infrared heating elements 133 inside the oven cabinet 300 will exit through the openings on both ends of the oven toaster cabinet 100. While the aforementioned radiation shield 124 (on the left side 104) intercepts infrared energy emitted from the left-side opening 122, IR from the oven cabinet 300 left side opening 122 will nevertheless heat surfaces that comprise the left side 104; IR emitted from the right side opening 128 on the right side 106 will heat surfaces on the right side 106 of the oven toaster 100.
As mentioned above, exterior surfaces of the cooking apparatus 100 are cooled by forced air. In
Room air 210 that flows through the fan 200-1 enters a plenum chamber 214 formed by the bottom panel 114 of the shell structure, the bottom panel 216 of the oven cabinet 300 and the front and back side panels 108 and 110 respectively. Room air in the plenum 214 effectively splits into a left-side flow and right-side flow, which are identified by reference numerals 210-L and 210-R due to the fact that the air 210 flows out the left and right sides of the plenum 214. The left side flow 210-L is driven by the fan 200-1 through an opening 210 in the front side wall 224 of the oven cabinet 300. The right side flow 210-R is driven by the fan 200-1 through a similar opening 210 formed in the rear side wall 228 of the oven cabinet 300.
A front-side, plenum chamber/air duct identified by reference numeral 232 is formed by a combination of panels that include the front side wall 224 of the oven cabinet 300, the exterior front, bottom and top panels of the shell structure 102 as well as the left and right side panels 104 and 106. A substantial air flow is generated inside the plenum/duct 232 due to one or both of the fans 200-1 and 200-2 forcing room air into the plenum/duct 232. A similar rear plenum/air duct 234 is formed on the opposite side of the oven 100 by the rear panel 110 of the shell structure 102, the bottom panel 114 of the shell structure, the top panel of the shell structure 112, and the left and right ends 104 and 106 respectively. The right side air flow 210-R that flows through the opening 220 and the rear side wall of the oven cabinet 228 creates air flow at the back side plenum 234 as well. Air from the plenums 232 and 234 flows into two different ducts 310 and 314 above the top panel 320 of the oven cabinet 300. The plenums and ducts 310 and 320, which are formed by sheet metal panels that stand off from each other, are configured with the fans, to route air over oven cabinet surfaces in such a way that the surface temperatures of the cooking apparatus 100, are kept below a temperature at which human skin will burn, even while the interior temperature of the oven cabinet 300 is as high as nine-hundred degrees Fahrenheit.
Referring now only to the first or left flow 210-L for brevity, the left-side flow 210-L goes toward the front panel 108 of the shell structure 102 and through an opening 220 in lower portion of the front side wall 224 of the oven cabinet 300. That air continues upwardly and around a thermally-insulated side cover 240 that covers electrical connections to the heating elements 133 that radiate IR inside the oven cabinet 300. An identical insulated side cover 240 covers the opposite rear side wall 262 of the oven cabinet 300. The side covers 240 are thermally insulated by a bed of fiberglass, not shown in the figures. Air that passes over the side covers 214 removes heat from their surfaces and continues upwardly toward the top or upper region of the respective plenums 232 and 234.
The aforementioned left-side air flow 210-L flows from the lower plenum 214, through the ventilation hole 220 and into the front side plenum 232. The forced air flow from the lower plenum flows through the front side plenum 232 (and the rear-side plenum 234). The left-side air flow 210-L is split into two separate flows as it passes out of the front side plenum 232 into two separate air ducts 310 and 314.
As best seen in
The top panel 320 of the oven cabinet 300 is provided with several holes 127 which extend through to the interior of the oven cabinet 300. Two, L-shaped duct forming/air directing panels 324 are attached to the top panel 320. They do not cover the holes 127 formed in the top panel 320 of the oven cabinet 300. The holes 127 formed in the top panel 320 are instead open to the ambient air through the holes 126 formed in the top panel 112 of the shell.
Together,
The oven cabinet 300 is comprised of the aforementioned front side wall 224 and a rear side wall 228. The left side panel 104 having the aforementioned hole or opening is opposite a similarly-shaped right side wall 106 having a corresponding right side opening 128. The oven top panel 320 is opposed by the bottom panel 114. Several air holes 126 are also formed or punched into the top panel 320 as an exhaust for air 210 that flows into lower duct openings 254. Two panels 324 are formed to define the top duct 310 and the panels 324 are lowered into place over the top panel 320 of the oven cabinet. These top duct-forming panels 324 have a rectangular face 326 that is perforated with holes 328. The perforations or holes 328 extend into the top duct 310. Since the top duct 310 carries a forced air flow from the plenums 232 and 234 on either side of the oven cabinet 300, air is urged outwardly through the perforations 328.
Air that flows through the L-shaped duct-forming panels 324 impinges on an over-hanging panel 340 that is part of the top panel 112 of the shell 102. The over-hanging baffle 340 defines an air gap between the panel 340 and the perforations 328. It deflects air downwardly across the ends of the oven 100 and across the corresponding openings 122 and 124. Air that leaves the perforations 328 thus provides a cooling air stream to the ends of the oven.
Some of the air flow 210-R enters the upper duct 310 while the remaining portion enters the lower duct 314. Air that flows into the lower duct 314 passes through the holes 126 formed in the top panel 320 of the oven cabinet 300. Air that flows into the top duct 310 passes through the aforementioned perforations and is directed downwardly by the baffle 340. Air streams identified by reference numeral 210 can be seen rolling downwardly and outwardly from the opening 120 in the left side 104 of the cabinet.
While there are only four sides shown in
The shell structure 920 is comprised of a lower panel 940 that is attached to yet spaced away from the bottom surface 924 of the oven cabinet 914. An upper panel 944 forms a top surface of the conveyor toaster oven 900, below which are two duct layers on top of each other. A left panel 946 of the shell structure is attached to yet spaced away from the left side 932 of the oven cabinet 914 to define a left side duct 950. A right panel 948 of the shell structure is attached to yet spaced away from the right side 934 of the oven cabinet 914 to define a right side duct 950.
The space between the exterior surface 922 of the oven and the panels that define the shell structure form a duct or plenum with one on the left side and another on the right side, both of which are identified by reference numeral 950. Room air, which is identified by reference numeral 210, enters the duct 950 through a fan located at an inlet port 960 or first end of the duct, which is located below the oven cabinet 914.
Air driven by the fan flows upwardly over the insulated sides 932 and 934 and across the top panel 928 of the oven cabinet. The air flows through a passage or exit 970 that leads to a secondary duct 975 that is spaced above the top panel 928. By the time room air 210 reaches the exit port 970, it has passed over metallic surfaces of the oven cabinet 314 that heat the room air 210 to a high temperature. Air 210 leaving the exit port 970 thus heats the top surface 944, which makes the duct layout of
In
In
Room air 210 is forced by the fan 200 into the lower plenum 214. The air essentially splits into two substantially equal air flows 210-L and 210-R. The left and right air flows go vertically and pass over the thermally-insulated left and right sides 932 and 934 of the oven cabinet 914. At the top surface 944 of the oven cabinet, the left and right-side air flows split; one flow passes through a first duct, which is directly over the top surface 944 of the oven cabinet. A second flow passes through a second duct that is directly over the first duct.
Air that passes through the first duct and which directly contacts the top of the oven merges with air that passes through the higher, second duct. Both flows pass through an exhaust port formed of the several, large-diameter holes 126 in a top surface of the toaster oven that is itself protected by a cage, not shown in the figures. The exterior surfaces of the toaster oven are therefore cooled by forced air to reduce or eliminate the risk of burns.
Those of ordinary skill in the art will appreciate that the foregoing description is for purposes of illustrating operation of the invention recited in the appurtenant claims. The true scope of the invention is indeed defined by the claims.