Cooking oven incorporating accurate temperature control and method for doing the same

IS 2 334 643 T3

DESCRIPTION

Baking oven that incorporates precise temperature control and a method to do the same.

Background of the invention

Invention field

In one aspect, this invention relates to an oven having precise temperature control, including a cooking cavity with heating elements for cooking and roasting independently controlled via separate temperature sensors located adjacent to each of corresponding heating elements. In another aspect, the invention relates to a method of independently controlling the heating elements for cooking and for toasting in the oven bake cavity during a cooking cycle of the oven.

Description of the associated technique

Gas and electric baking ovens are old and well known in the prior art. With reference to Fig. 1, these types of ovens 10 typically comprise a housing defining a cooking cavity 12 with an open face, in which the open face is closed by a hinged door 14. The open face housing is formed by opposing upper and lower walls, opposing end walls, and a rear wall. Adjacent to the upper wall of the baking cavity 12 is mounted a heating element 16 for toasting, and adjacent to the bottom wall of the baking cavity is mounted a heating element for baking 18. The side walls 20, 22 are provided with grating supports 24 which extend generally in a horizontal direction in the depth direction, within the cooking cavity 12, along the side walls 20, 22, to support on the same a grid to cook 26.

In prior art control methods for ovens 10, typically there is a single temperature sensor 28 located at a predetermined distance from each of the roasting and baking heating elements 16, 18, respectively, as described above. along a horizontal median plane of the cooking cavity 12, as illustrated in FIG. 1. This single temperature sensor 28 was typically used in the bake and toast modes of prior art ovens 10 to control the activation and deactivation of the heating elements for browning and baking 16, 18.

The use of a single temperature sensor 28 in prior art ovens 10, especially one such sensor 28 spaced a great distance from the associated roasting and baking heating elements 16, 18, has not proved to be a effective method of producing a constant and effective heating gradient across the vertical height of the cook cavity 12, since the heat rises and since the heat differential across the vertical height of the cook cavity can be substantially affected by various types of food products located on the cook pan 28 (for example, a frozen poultry product versus to a mixture at room temperature) and by the shape and size of the tray containing the food product.

For example, the tray interferes with the path of the vertical flow of hot air rising from the cookware. Typically, the larger the tray, the greater the interference. Interference means that heated air builds up along the bottom of the pan and flows around the sides of the pan, preventing even distribution across the top of the pan, resulting in resulting in a region of lower temperature of air above the tray and very hot air below the tray. The food product can exacerbate the low temperature region if the food product is at a temperature substantially lower than that of the surrounding air, effectively functioning as a source of cooling points. The end result is an undesirable temperature gradient on opposite sides of the tray.

The position of a single temperature sensor 28 at the upper end of the cook cavity 12 has been found to be ineffective in providing an input to a controller to turn the roast and cook heating elements 16 on and off. 18 so that they are able to reduce or eliminate the temperature gradient across the tray.

Attempts have also been made in the prior art to install multiple temperature sensors 28 in the bake cavity 12 of an oven 10, although those attempts in the prior art have been to solve problems unrelated to uniform heating throughout. the height of the oven cavity.

For example, US Patent No. 5,723,846 issued to Koether, et al., Dated March 3, 1998, describes the use of a pair of temperature sensors located adjacent to heating elements located both in an upper wall of a cooking cavity in a convection oven used for error detection purposes in the perception of error conditions in the convection oven.

In US Patent No. 5,791,890 issued to Maughan dated August 11, 1998, a temperature sensor located adjacent to each heating element is described for cooking and toasting in a gas oven used to the purpose of detecting a positive ignition test on each of the gas-based heating elements.

IS 2 334 643 T3

In US Pat. No. 5,332,886 issued to Schilling et al. On July 26, 1994, describes an electronic regulator for an electric oven that has a controller provided with a fixed program to process data from an actual temperature sensor and sensors. separate temperature settings, to produce error correction values ​​for the ambient temperature in the cooking cavity, to convert the dependency between the temperature values ​​of the actual temperature sensor and the temperature measuring device into additional process data.

In US-A-4 345 145 a method according to the preamble of claim 1 and an oven according to the preamble of claim 10 are described.

None of the dual sensor applications address the problem of accurately controlling the temperature in the oven bake cavity during an oven bake cycle to obtain even heat distribution across the height of the oven.

Summary of the invention

The invention relates to a method of accurately controlling the ambient temperature in a closed cooking cavity of an oven that is preheated with respect to a set point of temperature set by the user, the method comprising the features of claim 1.

The steps for determining a target temperature point may comprise calculating the set point for the heating element comprising one of a toast set point and a cook set point from the target temperature point. Calculating set points for items to cook and toast preferably comprises selecting the one of the set points to cook and toast from a data table containing a list of target temperature points and a corresponding list of at minus one of the set points for cooking and toasting. The set points for cooking and toasting comprise a range of temperature values ​​delimited by a low temperature limit and by a high temperature limit.

Alternatively, calculating the set points for roasting and cooking may comprise selecting a temperature differential value corresponding to the set target temperature point and adding the temperature differential value with that selected from at least one of the set points. for cooking and for toasting, to calculate the other of the at least one of the points established for cooking and for toasting. The temperature differential value can be negative or positive.

The step of sensing the temperature preferably comprises reading a sensor temperature signal comprising one of a cooking temperature signal and a roasting temperature signal read from the cooking temperature sensor and the cooking sensor. corresponding toasting temperatures.

Selective actuation of the heating elements for baking and toasting preferably comprises alternately activating the heating elements for baking and toasting. Alternative activation typically includes deactivating the heating element corresponding to the perceived temperature if the perceived temperature exceeds the corresponding heating point set for the element, activating the heating element corresponding to the perceived temperature if the perceived temperature is lower than that of the corresponding set point for heating element, and deactivating the heating element other than the heating element corresponding to the perceived temperature if the perceived temperature is lower than the set point for the heating element. Preferably, only one heating element is activated at a time. Furthermore, activation of the heating elements for cooking and toasting is continued, preferably during a predetermined duty cycle while the other element for cooking and toasting is deactivated.

The method may further comprise the step of detecting whether the oven is gas powered or electrically powered. If the oven is gas-fired, the method may include determining if a purge timeout has been met for the heating element for toasting.

The method may also comprise compensating the element heating set point based on an initial heating condition of the cooking cavity. The element heating set point is preferably increased in the compensation step. The compensation step may further comprise adjusting the heating set point of the element in accordance with a previously defined function, which is preferably a decreasing linear function.

In another aspect, the invention relates to an oven incorporating accurate room temperature control. The oven comprises the features of claim 10.

The controller preferably calculates the element heating set point comprising one of the toast set point and the cook set point, derived from the target temperature point. A sensor temperature signal comprising one of a baking temperature signal and a toasting temperature signal is read from the corresponding sensor of the heating element comprising one of the baking temperature sensor and the baking temperature sensor. toast. The controller preferably compares the temperature signal from the sensor with the heating element set point. The controller disables

ES 2 334 643 T3 the corresponding heating element if the sensor temperature signal exceeds the set point for the heating element. The controller also activates the corresponding heating element if the temperature signal from the sensor is lower than the set point for the heating element. The controller can turn off the heating element other than the corresponding heating element if the temperature signal from the sensor is less than the set point for the heating element.

Preferably, the controller includes a database comprising multiple target temperature points and the corresponding toast set points and cook set points, whereby the cook and toast set points can be selected from the chart according to with the target temperature point. Preferably, the set point for roasting and the set point for baking each comprise a range of temperature values ​​delimited by a low temperature limit and a high temperature limit.

The controller deactivates one of the cook and toast heating elements if one of the toast and cook elements is activated and if the corresponding cook or toast temperature signal exceeds the corresponding cook or toast set point by a predetermined amount. to toast. The controller activates one of the cook and toast heating elements for a predetermined duty cycle, provided the other of the cook and toast heating elements is deactivated.

The controller can compensate the set point for the heating element based on an initial heating condition of the cooking cavity. The compensation increases the set point for the heating element. Preferably, the compensation adjusts the set point for the heating element according to a previously defined function, which is preferably a decreasing linear function.

In yet another aspect, the invention relates to a method of maintaining a uniform temperature distribution in a bake cavity of an oven relative to a user-defined temperature set point. The baking cavity of the oven comprises a rack for supporting a tray, the rack functionally dividing the cavity into an upper heating region above the rack and a lower heating region below the rack. In the upper heating region, a heating element for browning is arranged together with a corresponding browning temperature sensor. In the lower heating region, a heating element is arranged for cooking together with a corresponding cooking temperature sensor. The method comprises the steps of providing a controller capable of acting on the toast and cook heating elements in response to the toast and cook temperature sensors; determining a target temperature point for the oven cavity based on the user-selected set temperature point; perceive the temperature in the upper and lower heating regions; compare the perceived temperatures to the target temperature point, and selectively actuate the roast and bake heating elements in response to the perceived temperatures to keep the temperature of the upper and lower heating regions substantially equal to the temperature point set as a goal.

Brief description of the drawings

In the drawings:

Fig. 1 is an inward looking perspective view of a prior art cook cavity of an oven with a door therefor depicted in a fragmentary perspective view, in which the cook cavity has a single oven sensor. temperature located near the upper end of the cooking cavity;

Fig. 2 is a perspective view with the same orientation as Fig. 1 but showing a cooking cavity for an oven according to the invention having separate temperature sensors, one located adjacent to a heating element for toasting at the top of the cooking cavity, and one located adjacent to a heating element for cooking located at the bottom of the cooking cavity.

Fig. 2A is a perspective view of the cooking cavity of Fig. 2, wherein on the rack in the cooking cavity a food product is placed in a cooking tray and arrows showing the path of heat in general around the cooking pan and the food product when the heating element for cooking is activated, thereby defining a dead heating zone above the food product;

Fig. 2B is a perspective view of the cook cavity of Fig. 2 where a food product is placed on a cook pan on the rack in the cook cavity and the arrows show the general heat path around the pan for cooking and from the food product when the heating element is activated for toasting, thus reducing the negative effects of cooking in the dead heating zone above the food product shown in Fig. 2A;

Fig. 3 is a block diagram showing the general components of the furnace of Fig. 2 configured for heating elements by means of electricity;

Fig. 4 is a block diagram showing the general components of the furnace of Fig. 2 configured for heating elements by means of gas;

IS 2 334 643 T3

Fig. 5 is a flow chart of the steps for controlling the temperature of the cooking cavity of the ovens shown in Figs. 2-4, which specifically indicates the steps to collect information from a user, determine the specific parameters for the cooking mode and preheat the oven cavity using those established parameters, to proceed as indicated in the flow chart represented in Fig. 6;

Fig. 6 is a flow chart continuing from point "A" of Fig. 5 and shows a main set of steps to check the temperature sensors depicted in Fig. 2 adjacent to each of the heating elements for cooking. and for toasting and proceeding in threads in Figs. 7, 8, 9 and 10 as indicated by the thread calls "B", "D", "E", and "G", respectively;

Fig. 7 is a flow chart showing the steps of the method that are executed if sub-process "B" is passed from Fig. 6;

Fig. 8 is a flow chart showing the steps of the method that are executed if sub-process "D" is passed from Fig. 6;

Fig. 9 is a flow chart showing the steps of the method that are executed if the sub-process "E" is passed from Fig. 6;

Fig. 10 is a flow chart showing the steps of the method that are executed if the sub-process "G" is passed from Fig. 6; Y

Fig. 11 is a flow chart showing a compensation routine for various set temperature points employed in the method steps of Figs. 6-10 for compensation of the set temperature points in relation to the heating elements for cooking and for roasting due to a typical exceeding of the desired temperature in the cooking cavity during the preheating of the oven, whereby the compensation steps from Fig. eleven They artificially increase the target points of the heating elements for roasting and cooking to avoid extended control downtimes during controlled heating of the oven cavity during a cook cycle.

Description of the preferred embodiment

Referring now to the drawings and Figs. 2-4 in particular, oven 10 has been shown in Figs. 23 configured for electric heating elements and in Fig. 4 for gas heating elements, in which there is a roasting temperature sensor 30 located adjacent to a roasting heating element 16 and there is a Bake temperature sensor 32 located adjacent to a bake heating element 18. The browning temperature sensor 30 and the baking temperature sensor 32 are interconnected with a controller 34.

It will be understood that the common elements that the oven 10, represented in Figs. 2-4, with the prior art oven, shown in Fig. 1, have been designated by common reference numerals, that is, that the cooking cavity 12, the door 14, the heating elements 16, 18, side walls 20, 22, grate supports 24, and cooking grate 26 are designated in Figs. 2-4 with the same reference numbers as those in Fig. 1.

In Figs. 3-4 block diagrams of electric furnaces and gas furnaces, 10, respectively, have been represented, since the particular mechanical interconnection and the set of elements of the block diagrams represented in Figs. 3-4 are not critical to the invention, and any of the well-known components that make up prior art ovens will suffice since this invention relates to the method of controlling the roasting temperature sensor 30 and the roasting sensor 32. cooking temperature.

With reference to Figs. 3-4, the general components that make up the oven 10 according to the invention include a oven chassis 36 that supports the components that make up the oven 10 on a floor 38. An anti-tip bracket 40 mechanically couples the frame 36 to either the the floor or the wall to prevent the oven from tipping when a heavy weight is placed on the door 14. Door 14 is typically mounted to chassis 36 by hinge 42 and maintains the integrity of cook cavity 12 by seal 44 which is preferably effective in preventing heat from escaping from cavity 12.

Typically, a heat / storage drawer 46 is disposed in a lower portion of the chassis 36 and mounted thereon by conventional sliders 48 that allow sliding movement of the heat / storage drawer 46 relative to the chassis 36. The heating / storage drawer 46 is typically provided with its own heating element 50 interconnected with the controller 34 and actuated by the controller 34 through a signal from a temperature sensor 52 located within the heating / storage drawer 46. .

The oven 10 may also include a conventional plate 54 typically comprising a number of burners or elements 56 on the plate. In the electric oven 10 shown in Fig. 3, the burners / elements 56 of the plate are interconnected with a supply of electric power 58 through a switch 60, as is known

ES 2 334 643 T3 conventionally. In the gas furnace 10 shown in Fig. 4, the burners / plate elements 56 are interconnected to a gas supply line 62 by means of a regulator 64 and various valves 66, also as is conventionally known. In both embodiments of Figs. 3-4, the power supply 58 is also interconnected with the controller 34 to supply power thereto.

Also mounted on chassis 36 is a latch 65 preferably interconnected with controller 34 and door 14. User 67 manually actuates latch 65 to latch the door to chassis 36 to lockably close cavity 12. In addition, controller 34 can send a signal to latch 65 to automatically lock door 14 on chassis 36, closing the cavity during oven cleaning operations, thus preventing user 67 from opening door 14.

In the electric oven 10 depicted in FIG. 3, the roasting heating element 16 and the baking heating element 18 are directly interconnected with the controller 34, which controllably supplies energy from the power supply 58 for heating. selectively cavity 12 in a controlled manner. In the gas version represented in Fig. 4, the roast heating element 16 and the roast heating element 18 are interconnected with the controller 34 by means of a gas control assembly 68 comprising a spark jump module 70 (i.e., an igniter) for passing a spark to an electrode 72 which, in turn, interacts with a volume of gas released by a solenoid valve 74 that is interconnected with gas supply line 62 via regulator 64.

The controller 34 is interconnected with a control panel 76 mounted on the chassis 36 and containing, among other things, actuating devices such as control buttons that allow the user 67 to set, among other things, the particular heating mode of the oven 10 (for example, COOK, TOAST, CLEAN, etc.) and, to the extent that the user has selected the heating mode, either to cook or to toast, a temperature point, set as a target, to which the user wishes to cook food products in the cooking cavity 12.

For the purposes of flowcharts here describing the inventive method of Figs. 5-11, it is assumed that user 67 has accessed control panel 76 and has set the oven heating mode to COOK and has operated other control buttons on the oven to set a target temperature point. (ie, the desired temperature to which the cook cavity 12 is to be heated and closely controlled and maintained at that temperature during the COOK cycle).

In a typical control knob to set the target temperature point TEMP_TARK, the user is typically allowed 67 to select from several temperatures in 15-30 degrees C (25-50 degrees Fahrenheit) increments such as 95, 120, 150, 163, 175, 205, 230, 245, etc. in degrees C (200, 250, 300, 325, 350, 400, 450, 475 ° F, etc.). The method to control the temperature of the cooking cavity 12 at the target temperature point, selected by the user TARGET_TEMP in the COOK mode, has been represented at 100 in Fig. 5. Once these parameters have been established by the The user at step 100 proceeds to step 102, in which further cooking mode parameters are determined by controller 34 from a database 104. The database 104 can be any typical look-up table or a relational database that supplies data to the controller 34 based on the make and / or model of oven 10 used. An example of the database can be seen in the following Table 1.

TABLE 1

Time and Temperature Points Established in the Cooking Method (Temperatures in degrees C and times in seconds)

<td></td><td>TO</td><td>B</td><td>C</td><td>D</td><td>AND</td><td>F</td><td>G</td><td colspan="2">Η II</td><td>J</td><td>K</td><td>L</td>

<td rowspan="2">Temp Band</td><td rowspan="2">Target</td><td colspan="2">Preheating</td><td colspan="2">Toast</td><td colspan="2">Cook</td><td colspan="2">Toast</td><td colspan="2">Cook</td><td rowspan="2">Delta</td>

<td>Toast</td><td>Cook</td><td>Established Point</td><td>Amplitude</td><td>Established Point</td><td>Amplitude</td><td>Cycle Time</td><td>Connected Time</td><td>Cycle Weather</td><td>Connected Time</td>

<td></td><td> 95</td><td> 112</td><td> 112</td><td> 86</td><td> 0,5</td><td> 83</td><td> 0,5</td><td> 60</td><td> 15</td><td> 60</td><td> 60</td><td> 3</td>

<td>SHORT</td><td> 120</td><td> 137</td><td> 137</td><td> 114</td><td> 0,5</td><td> 111</td><td> 0,5</td><td> 60</td><td> 15</td><td> 60</td><td> 60</td><td> 3</td>

<td></td><td> 150</td><td> 167</td><td> 167</td><td> 142</td><td> 0,5</td><td> 139</td><td> 0,5</td><td> 60</td><td> 15</td><td> 60</td><td> 60</td><td> 3</td>

<td></td><td> 163</td><td> 180</td><td> 180</td><td> 156</td><td> 0,5</td><td> 153</td><td> 0,5</td><td> 60</td><td> 15</td><td> 60</td><td> 60</td><td> 3</td>

<td></td><td> 165</td><td> 182</td><td> 182</td><td> 157</td><td> 0,5</td><td> 150</td><td> 0,5</td><td> 60</td><td> 35</td><td> 60</td><td> 60</td><td> 7</td>

<td>HALF</td><td> 175</td><td> 192</td><td> 192</td><td> 168</td><td> 0,5</td><td> 161</td><td> 0,5</td><td> 60</td><td> 35</td><td> 60</td><td> 60</td><td> 7</td>

<td></td><td> 205</td><td> 222</td><td> 222</td><td> 196</td><td> 0,5</td><td> 189</td><td> 0,5</td><td> 60</td><td> 35</td><td> 60</td><td> 60</td><td> 7</td>

<td></td><td> 227</td><td> 244</td><td> 244</td><td> 218</td><td> 0,5</td><td> 211</td><td> 0,5</td><td> 60</td><td> 35</td><td> 60</td><td> 60</td><td> 7</td>

<td>HIGH</td><td> 230</td><td> 241</td><td> 241</td><td> 223</td><td> 0,5</td><td> 215</td><td> 0,5</td><td> 60</td><td> 40</td><td> 60</td><td> 60</td><td> 8</td>

<td></td><td> 245</td><td> 256</td><td> 256</td><td> 237</td><td> 0,5</td><td> 229</td><td> 0,5</td><td> 60</td><td> 40</td><td> 60</td><td> 60</td><td> 8</td>

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TABLE 1a

Time and Temperature Points Established in the Cooking Method (Temperatures in degrees F and times in seconds)

<td></td><td>TO</td><td>B</td><td>C</td><td>D</td><td>AND</td><td>F</td><td>G</td><td colspan="2">Η II</td><td>J</td><td>K</td><td>L</td>

<td rowspan="2">Temp Band</td><td rowspan="2">Target</td><td colspan="2">Preheating</td><td colspan="2">Toast</td><td colspan="2">Cook</td><td colspan="2">Toast</td><td colspan="2">Cook</td><td rowspan="2">Delta</td>

<td>Toast</td><td>Cook</td><td>Established Point</td><td>Amplitude</td><td>Established Point</td><td>Amplitude</td><td>Cycle Weather</td><td>Connected Time</td><td>Cycle Time</td><td>Connected Time</td>

<td></td><td> 200</td><td> 230</td><td> 230</td><td> 188</td><td> 1</td><td> 182</td><td> 1</td><td> 60</td><td> 15</td><td> 60</td><td> 60</td><td> 6</td>

<td>SHORT</td><td> 250</td><td> 280</td><td> 280</td><td> 238</td><td> 1</td><td> 232</td><td> 1</td><td> 60</td><td> 15</td><td> 60</td><td> 60</td><td> 6</td>

<td></td><td> 300</td><td> 330</td><td> 330</td><td> 288</td><td> 1</td><td> 282</td><td> 1</td><td> 60</td><td> 15</td><td> 60</td><td> 60</td><td> 6</td>

<td></td><td> 325</td><td> 355</td><td> 355</td><td> 313</td><td> 1</td><td> 307</td><td> 1</td><td> 60</td><td> 15</td><td> 60</td><td> 60</td><td> 6</td>

<td></td><td> 330</td><td> 360</td><td> 360</td><td> 314</td><td> 1</td><td> 302</td><td> 1</td><td> 60</td><td> 35</td><td> 60</td><td> 60</td><td> 12</td>

<td>HALF</td><td> 350</td><td> 380</td><td> 380</td><td> 334</td><td> 1</td><td> 322</td><td> 1</td><td> 60</td><td> 35</td><td> 60</td><td> 60</td><td> 12</td>

<td></td><td> 400</td><td> 430</td><td> 430</td><td> 384</td><td> 1</td><td> 372</td><td> 1</td><td> 60</td><td> 35</td><td> 60</td><td> 60</td><td> 12</td>

<td></td><td> 440</td><td> 470</td><td> 470</td><td> 424</td><td> 1</td><td> 412</td><td> 1</td><td> 60</td><td> 35</td><td> 60</td><td> 60</td><td> 12</td>

<td>HIGH</td><td> 450</td><td> 470</td><td> 470</td><td> 434</td><td> 1</td><td> 420</td><td> 1</td><td> 60</td><td> 40</td><td> 60</td><td> 60</td><td> 14</td>

<td></td><td> 475</td><td> 495</td><td> 495</td><td> 459</td><td> 1</td><td> 445</td><td> 1</td><td> 60</td><td> 40</td><td> 60</td><td> 60</td><td> 14</td>

The example database 104 depicted in Table 1 has twelve columns consecutively designated by the letters AL. Column A of Table 1 corresponds to the target temperature point, TARGET_TEMP, set by user 67 on control panel 76. Table 1 contains several rows that each correspond to the typical temperature settings of a control button on the control panel 76, to set the desired target temperature point TARGET_TEMP. Table 1 shows several rows corresponding to those typical values ​​in degrees Celsius, ° C, including the values ​​of 95, 120, 150, 163, 165, 175, 205, 227, 230, and 245 (equivalent to 200, 250, 300 , 325, 330, 350, 400, 440, 450 and 475 ° F). It is assumed that this invention is known not to be limited by the values ​​depicted in Table 1, as these should be construed only as an example of the data used by controller 34 and not to be construed as limiting the invention.

Table 1 also includes a first column that groups the rows of Table 1 into low, medium and high temperature bands, in which the low temperature band ranges from 95 to 163 ° C (200 to 325 ° F), the band Medium temperature ranges from 165 to 227 ° C (330-440 ° F) and the high temperature band ranges from 230 ° C (450 ° F) onwards. These groupings were made by selection by trials. It has been found that the particular heating margins such as those of the low, medium and high temperature bands represented in Table 1, each have common characteristics that allow certain equations to be attributed individually to the two target temperatures that fall within those target temperature bands, as will be described in more detail below.

Columns B and C of database 104 depicted, for example, in Table 1, include target temperature points for the roasting heating element 16 and the baking heating element 18, respectively. These values ​​represent the targets that are desired to be read by the toasting temperature sensor 30 and by the cooking temperature sensor 32 during the preheating of the oven 10. It will be noted that the preheat target temperature for roasting in column B and the target preheat temperature for baking in column C exceed the target temperature in column A at 17, 17 and 11 (30, 30 and 20) for the low, medium and high temperature bands, respectively.

It should not be understood as limiting for this invention that the target preheat, toast, and preheat to cook temperatures have been represented as equal values, since it is also contemplated that those values ​​may differ in a different oven preheat cycle. In addition, the "overshoot" differences, that is, the amount by which the preheat to roast and preheat to cook temperatures in columns B and C of database 104 in Table 1, exceed the set temperature point. As a target for column A, they may also be selected as different values, without thereby exceeding the scope of this invention, since those values ​​represented are given by way of examples, and not limitation.

Columns DE and FG from database 104 depicted, for example, in Table 1, contain a target point and span range for the heating element for roasting 16 and for the heating element for cooking 18 to be detected by the temperature sensor 30 for roasting and by the temperature sensor 32 for baking, respectively, during the COOK mode, as selected by user 67 for a temperature point set as a particular target TEMP_ TARGET. These values ​​allow the controller 34 to calculate the low temperature limit and high temperature limit set points for the roasting heating element 16 and for the cooking heating element 18.

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For example, for a temperature point set as a particular target TEMP_ARTICLE selected by user 67, database 104 looks up a corresponding value in Column A and sets a variable point TOAST_SET for the value in Column D, for example 168 ° C (334 ° F) for a desired target temperature TARGET_TEMP of 175 ° C (350 ° F). Controller 34 then calculates a low temperature limit for the roasting heating element, TOSTAR_LBT, of 175 ° C (350 ° F) by subtracting the amplitude in Column E from the temperature point set in Column D and calculates a high temperature limit of the heating element for roasting TOSTAR_LAT by adding the amplitude in Column E to the temperature of the set point for roasting in Column D.

For example, at a user-selected TARGET_TEMP temperature set point 67, database 104 looks up a corresponding value in Column A and sets a COOK_SET variable for the value in Column F (for example, 161 ° C (322 ° F)) at a desired target temperature point TEMP_TARO of 175 ° C (350 ° F). Controller 34 then calculates a heating element temperature low limit for cooking COCER_LBT, by subtracting the amplitude of Column G from the temperature of the set point in Column F and calculates a heating element high temperature limit for cooking. COCER_LAT, adding the amplitude that appears in Column G to the temperature point set for cooking in Column F.

Columns H and I define the duty cycle for the heating element for toasting 16, that is, the period of time that comprises the normal heating cycle of the heating element for toasting 16 and the period of time (in seconds) that toast heating element 16 is on during that time. Column H represents the TOAST_CYCLE time that the toast heating element 16 remains on when a signal to activate the toast heating element 16 occurs from the controller 34. Column I represents the TOAST_OFF time in seconds where the roasting heating element is actually giving off heat during the ROAST_CYCLE. For example, for a desired target temperature of 175 ° C (350 ° F), toast heating element 16 has a total cycle time of 60 seconds (Column H for a target temperature point of 175 ° C ( 350 ° F) in Column A) and the toast heating element remains on for approximately 35 seconds of that 60 second time (Column I at a target temperature point of 175 ° C (350 ° F) in Column TO).

Columns J and K define the duty cycle for the firing element 18, that is, the time span that comprises the normal heating cycle of the firing element 18 and the span of time (in seconds) in that the heating element for cooking 18 is on during that time. Column J represents the time span COOK_CYCLE the heating element to cook 18 is on upon receiving a signal to activate the heating element to cook 18 from the controller 34. Column K represents the time span, in seconds, of COOK_ON in that the cooking heating element 18 is actually emitting heat during COOK_CYCLE. For example, for a desired target temperature of 175 ° C (350 ° F), the cooking heating element 18 has a total cycle time of 60 seconds (Column J at a target temperature point of 175 ° C ( 350 ° F) in Column A) and cook heating element 18 remains on for approximately 35 seconds of that 60 second time (Column K for a desired target temperature point of 175 ° C (350 ° F) in Column A).

Column L is an optional column in the database, which is essentially used as a tool to conserve the memory of the controller 34 by creating a DELTA value in column L, which defines the relationship between the set point to cook in Column F and the set point for toasting in Column D, that is, that DELTA in Column L represents the number of degrees F that the set point for roasting in Column D exceeds the set point for cooking in Column F. Therefore, if the DELTA value is used in Column L, one of the set point for roasting in Column D and the set point for cooking COOK_ESTABLISHED in Column F is unnecessary, since the other of these two values ​​could be calculated by adding or by subtracting the DELTA value in Column L from either Column D or Column F.

Consequently, memory can be conserved by using the smallest number of bits to represent the DELTA value in Column L, instead of the largest number in either Column D or Column F (TOAST_ESTABLECER or COCER_ESTABLECER), which require more bits to store that value in memory. Although this memory economy may not be a concern for controllers 34 that have large amounts of RAM or ROM, the memory economy technique can be significant for controllers 34 with smaller amounts of memory.

In summary, when the user sets the set temperature point as the desired target TEMP_ TARGET and selects the cooking mode on the control panel 76 in step 100, the process continues in step 102 where the controller 34 searches and calculates the following cooking parameters from database 104, represented, for example, in Table 1. All values ​​in Table 1 have been given in degrees ° C and all times in seconds. All temperature values ​​in Table 1a are given in degrees ° F. Also, in the following equations, a capital letter in parentheses (for example, (D)) represents a value in the column identified by the letter between

ES 2 334 643 T3 parentheses at the intersection of the row corresponding to the temperature point set as the desired target TEMP_ TARGET set by user 67 in control panel 76.

TOAST_ESTABLECER = (D) (o) (F) + (L);

TOAST_LBT = TOAST_ESTABLECER - (E);

TOAST_LAT = TOAST_ESTABLECER + (E);

COOK_ESTABLECER = (F) (o) COOK_ESTABLECER - (L);

COCER_LBT = COCER_ESTABLECER - (G);

COCER_LAT = COCER_ESTABLECER + (G);

TOAST_CICLO = (H);

TOAST_ON = (I);

COCER_CICLO = (J);

COOK_ON = (K); Y

DELTA (if used) = (L).

Database 104 can also be used to look up the temperatures of preheat target points TOAST_PRE = (B) and COCER_PRE = (C).

It is important to note that the parameters and corresponding values ​​depicted in Table 1 are illustrative and not limiting of the invention. The particular values ​​for each of the parameters may vary depending on the particular characteristics of the oven, such as, for example: the volume of the cooking cavity, the heating output of the toaster, the heating output of the oven, and the time. desired response in the event of exceeding the initial temperature. The particular values ​​for a given furnace can be determined by standard test procedures.

Once those values ​​have been established, the process proceeds to step 106, in which the oven is preheated using the parameters looked up in database 104 in step 102. The preheat routine is relatively simple and refers to selectively actuate the roast heating element 16 until the roast temperature sensor 30 reads too much TOAST_PRE and selectively act the roast heating element 18 until the temperature sensor to cook 32 mark an excess of COCER_PRE. It is preferred that the roasting heating element 16 and the baking heating element 18 are operated independently of each other, so that at no time is the roasting heating element 16 on at the same time as the heating element for cooking. cook 18, since actuation of both heating elements 16 and 18 simultaneously can cause the rate of rise in ambient temperature in cook cavity 12 to increase dramatically, often beyond the ability of controller 34 to compensate for that rise. It will also be understood that the roasting heating element 16 and the baking heating element 18 are preferably operated in accordance with their duty cycles defined in Columns HI and JK by the parameters TOAST_CYCLE, TOAST_ON, COOK_CYCLE and COOK_ON, determined in step 102 for a search of database 104.

Once the oven has been preheated, typically exceeding the desired target temperature TARGET_TEMP, the process follows the connection flow chart of Fig. 6 through connector "A".

To understand the details of the operation, an overview of the control process will be helpful. After setting the control parameters (Fig. 5), the heating elements for roasting and cooking 16 and 18 are activated, to maintain the temperature of the cavity adjacent to the corresponding temperature sensors for roasting and cooking 30 and 32 between the points established as high and low temperature limits, respectively (Fig. 6).

It is preferred that none of the cook or toast items be activated simultaneously (Figs. 7-10) and priority is given to the cook item (Fig. 7). In other words, if you require both heating elements for cooking and heating elements for toasting to be activated, the element for cooking is activated, even if the element for toasting has to be switched off.

The advantages of the alternate actuation of the heating elements for cooking and roasting (18 and 16) can be seen by examining Figs. 2A and 2B. Fig. 2A is a perspective view of the cooking cavity 12 of Fig. 2, in which a food product (80) contained in a cooking tray 82 is placed on the rack 26 in the cooking cavity 12. As can be seen in Fig. 2A, arrows illustrate the general path of heat around cooking pan 82 and food product 80 when cooking heating element 18 is activated.

IS 2 334 643 T3

Since the heat from the cooking heating element 18 generally follows a path around the cooking pan 82 and the food product 80 and then rises generally vertically, a heating dead zone 84 is defined above the food product 80. wherein the heat from the cooking heating element 18 does not effectively cook the food product 80. In the case of a low temperature item such as a frozen bird, that heating dead zone 84 can cause significant detriment to the cooking of the food product 82.

This invention addresses that problem by periodically activating the roasting heating element 16 based on signals from the roasting temperature sensor 30, in addition to periodically activating the roasting heating element 18 based on signals from the temperature sensor. for cooking 32. This causes heat to be applied to the food product 80 also from above, as illustrated in Fig. 2B. The arrows in Fig. 2B represent the overall heat going to the food product 80 from the roasting heating element 16, directly through the heating dead zone 84, thus reducing the negative effects for the cooking operation of the dead heating zone 84 by above the food product 80.

Fig. 6 depicts the main control routine for controlling the temperature in the cook cavity 12 of oven 10. The process then proceeds to step 108, in which the controller accepts a COCER_TEMP signal from the temperature sensor 32 to cook, which is an indicator of the temperature in cavity 12 at the location of sensor 32. The process proceeds to decision point 110, where it is determined whether the COOK-TEMP exceeds the desired high temperature limit for the heating element for COCER_LAT cooking. If so, the process passes to the thread depicted in Fig. 7 through connector "B" of Fig. 6. If it is not, the process proceeds to decision point 112.

At decision point 112, it is determined whether the value of the COCER_TEMP signal, emitted by the cooking temperature sensor 32, is less than the desired lower temperature limit for the cooking heating element 18 COCER_LBT. If so, the thread depicted in Fig. 8 is called through the "D" connector depicted in Fig. 6. If it is not, the process continues to step 114.

In step 114, the controller 34 receives a signal from the toast temperature sensor 30 corresponding to the TOAST_TEMP temperature read by the toast temperature sensor 30. It is also to be noted that the process returns from the thread indicated by " B "and of the thread identified by" D "to the step of the method represented in Fig. 6 by means of the connector represented as" C ", which also returns the process of those threads to step 114.

The process then proceeds to decision point 116. At decision point 116, controller 34 determines whether the TOAST_TEMP value read in step 114 exceeds the desired high temperature limit for toast heating element 16 TOAST_LAT. If so, the thread depicted in Fig. 9 is called, as indicated by connector "E" in Fig. 6. If it is not, the process proceeds to decision point 118.

At decision point 118, controller 34 determines if the value read by sensor 30 of the temperature for roasting TOAST_TEMP is less than the desired lower temperature limit for the heating element for toasting 16 TOAST_LBT. If so, the thread in Fig. 10 is called as indicated by connector "G" in Fig. 6. If not, the process continues to the intermediate point indicated by connector "F" in Fig. 6. At which point the process returns to step 108.

It is also to be noted that the thread of Fig. 9, as indicated by the connector "E" in Fig. 6, and the thread of Fig. 10 indicated by the connector "G", returns in each of them to be processed to the connector indicated as "F" in Fig. 6 and thus also returns to step 108 to continue the processing of the main loop represented in Fig. 6.

FIG. 7 depicts the thread called by decision point 110 if the temperature signal COCER_TEMP read in step 108 exceeds the desired high temperature limit for the heating element for cooking COCER_lAt. The process then returns to decision point 120, at which point controller 34 determines if heating element for cooking 18 is OFF. If the heating element for cooking is OFF, the thread simply goes back through the connector represented as "C", where the process is returned to step 114 of Fig. 6.

If the heating element for cooking 18 is ON, the process continues to step 122 where the controller deactivates the heating element for cooking 18. Processing then returns to step 114 of Fig. 6 through the connector represented at "C" . The net effect of this thread is to turn off the cook heating element 18 if the cook temperature sensor 32 reads a COCER_TEMP temperature higher than the COCER_LAT high temperature limit determined in database 104.

FIG. 8 depicts the method steps performed when decision point 112 determines that the temperature signal emitted by the temperature sensor for baking 32 COCER_TEMP is less than the lower limit of the temperature for heating element 18 COCER_LBT. The process then proceeds to decision point 124 where controller 34 determines whether toasting heating element 16 is currently off, that is, it is in the OFF state. If so, the process continues to step 126 where the element is activated

ES 2 334 643 T3 heating to bake for its predefined duty cycle determined by controller 34 in database 104.

Specifically, the duty cycle activates the heating element to cook 18 for a cycle of COOK_CYCLE seconds, during which the heating element to cook 18 is turned on for COOK_ONNECTED seconds of that total cycle time at a temperature of COOK_SET degrees C. It is to be noted that the duty cycle of the cooking heating element 18 begins at step 126 and continues by returning the process through connector "C" to step 114 in FIG. 6.

The net effect of the thread steps in Fig. 8 is, once a determination has been made that the cooking temperature sensor 32 is marking a COCER_TEMP temperature lower than the desired lower temperature limit for the cooking heating element 18 COCER_LBT the duty cycle for the heating element for baking 18 but only after deactivating heating element for toasting 16, to ensure that the roasting heating element and the cooking heating element 16 and 18 are not operated at the same time, which can cause a sudden uncontrolled rise in temperature in the cooking cavity 12.

FIG. 9 depicts the thread called by decision point 116 if the TOSTAR_TEMP temperature signal dialed in step 116 exceeds the desired high temperature limit for the heating element for toasting 16 TOSTAR_LAT. The process then proceeds to decision point 128, at which point controller 34 determines whether toasting heating element 16 is OFF. If the heating element for toasting 16 is OFF, the thread simply returns through the connector represented as "F", thereby turning the process through the connector "F" to Fig. 6. If the heating element Toast 16 is ON, the process continues to step 130 where controller 34 deactivates heating element 16 to toast. The process then returns to Fig. 6 through the connector depicted at "F". The net effect of this thread is to turn off the roast heating element 16 if the roast temperature sensor 32 reads a TOSTAR_TEMP temperature higher than the TOSTAR_LAT high temperature limit determined in database 104.

Fig. 10 depicts the thread that is called at a decision point 118 when the controller 34 determines that the TOAST_TEMP temperature signal sent by the toast temperature sensor 32 is less than the desired lower temperature limit for the toast element. heating to toast 16 TOAST_LBT. If so, the process continues along connector "G" from Fig. 6 to Fig. 10, to decision point 132.

At decision point 132, controller 34 determines whether cooking heating element 18 is currently on, that is, in an ON state. If so, the process returns to Fig. 6 via connector "F", which thereby returns the process to step 108 of Fig. 6. If the heating element for cooking 18 is not currently ON, the process proceeds to decision point 134, where the controller checks if it is an electric oven 10 or a gas oven 10. If it is detected that it is a gas oven 10 (that is, the test to see if it is an electric oven is negative), the process goes to decision point 136. At decision point 136, the controller 34 determines if the burner purge time of the heating element to toast 16 has been reached (gas systems require a certain amount of time to elapse before a heating element can be reactivated). heating).

If the burner purge time has not elapsed, the process proceeds to step 138 at which time the cooking heating element 16 is purged in the gas oven, in a manner well known in the art. After which, the process continues to step 140.

It should also be noted that if the test at decision points 134 and 136 gives an affirmative result, that is, that it is an electric oven 10 or that the purge time for the heating element for toasting 16 has elapsed, the process also proceeds directly to step 140. In addition, the cycle can be optimized for either an electric oven or a gas oven, if instead of the illustrated process in which the type of oven is verified, if it is optimized for a type of oven, it can be dispensed with oven-specific process steps not optimized.

In step 140, the duty cycle for the roasting heating element 16 is started, in the same manner as described with respect to the duty cycle for the cooking heating element 18 in step 126 of FIG. 8. Specifically, a duty cycle of a total cycle time of TOAST_CYCLE seconds is activated, during which toast heating element 16 is activated and emitting heat for TOAST_ONNECT seconds of that total cycle time.

After initiating the duty cycle for the roasting heating element 16 in step 140, the process returns along the connector "F" to its corresponding connection point "F" in Fig. 6, in which it returns then the process to step 108 to repeat the steps of Fig. 6.

The net effect of the steps depicted in Fig. 10, once it has been established that the TOAST_TEMP temperature detected by the toast temperature sensor 30 is less than the desired lower temperature limit TOAST_LBT of the toast heating element 16, is that of leave the heating element to cook 18 on

ES 2 334 643 T3 its current connected state when the thread in Fig. 10 is called. Otherwise, if the heating element for baking 18 is disconnected, the work cycle for the heating element for toasting is immediately started. 16 in step 140 for an electric oven, as determined in decision step 134. For a gas oven 10, the controller 34 ensures that the time for purging the toast heating element 16 has elapsed, and only then does the duty cycle for the toast heating element begin in step 140.

As mentioned above, once the duty cycle has started in step 140, the process returns via connector "F" to Fig. 6, where the cycle of Fig. 6 is repeated until the time to cook is fulfilled or it is canceled by the user. Toast and bake heating elements 16 and 18 are activated by controller 34 as required, with priority being given to bake heating element 18.

The basic invention described herein is believed to be the concept of employing a pair of temperature sensors, i.e., the bake temperature sensor 32 located adjacent to the bake heating element 18 and the browning temperature sensor 30 located adjacent to the roasting heating element 16, to independently control the corresponding heating elements. Since the roasting and baking temperature sensors 30, 32 are located relatively close to their respective roasting and baking heating elements 16, 18, respectively, the temperature sensors 30, 32 are available to allow the heating elements to heating for roasting and baking 16, 18 are controlled independently, based on a signal from the corresponding temperature sensor 30, 32. The signal from the sensors is also more indicative of the local temperature of the oven cavity corresponding to the position of the respective heating element. Accordingly, better temperature control and greater precision can be achieved within the bake cavity 12 of the oven 10.

The relative spacing of the sensor and the corresponding element can vary from that described in the drawings, without exceeding the scope of the invention. If the spacing is large enough, some of the high and low element set points may have to be altered to maintain the desired uniform temperature distribution throughout the oven cavity. What matters to the invention is that the toasting element is used to control the local temperature of the part of the oven above a tray in the oven cavity, that the cooking element controls the local temperature below the tray, and that the elements collectively control the overall temperature of the entire oven cavity through independent localized temperature control.

This invention has been found to be of equal applicability and value for its implementation in both electric and gas ovens, as described above with respect to Figs. 3 and 4, respectively. It will be understood that the roasting heating element 16 and the baking heating element 18 may be any of the well-known heating elements, such as wire-based or coil-based heating elements, such as those typically used in ovens. electric, or gas oven burners used in gas ovens.

The database 104 represented as an example in Table 1 illustrates that different set temperature points are established, that is, from TOAST_ESTABLECER and from COOK_ESTABLECER, for the corresponding temperature sensor for roasting 30 and the corresponding temperature sensor for cooking 32, which can be a function of the position of the particular temperature sensor 30, 32 in its corresponding heating element 16, 18, respectively. It is also to be noted that, as described above, the preheat temperatures TOAST_PRE and COOK_PRE are preferably higher than the corresponding desired target temperature TARGET_TEMP set by user 67 on control panel 76 when starting the heating cycle in mode. COOK from oven 10. In addition, the toast heating element 16 and bake heating element 18 duty cycles can be started in different duty cycles, as defined by the TOAST_CYCLE, TOAST_CONECTED, COOK_CYCLE, and COOK_CONNECTED set point, as appropriate to the target temperature set point. particular TARGET_TEMP for roasting heating element 16 and for baking heating element 18, as determined by the target points for each heating element, that is, for TOAST_SET and COOK_SET, respectively.

In the example illustrated in Table 1, the heating element for toasting 16 is operated following a certain duty cycle previously established for the operating bands defined as low, medium and high temperature, and the heating element for Bake 18 is operated during a different duty cycle for each of those temperature bands. In the example illustrated in Table 1, the heating element for cooking 18 is operated following a 100% duty cycle for each of the temperature bands, that is, that COOK_CYCLE = COOK_CONNECTED, thus defining that the element Heating to Cook is activated for the entire work cycle time for the heating element to cook 18.

A compensation method has also been contemplated in the method of the invention described herein since, during the preheating of the cooking cavity 12 of the oven 10, the temperature of the cooking cavity typically exceeds the desired temperature TARGET_TEMP set by the user 67 in control panel 76. Consequently, after the preheat cycle is completed, there is typically a period of inactivity during which the actual ambient temperature within the cook cavity 12 of the oven 10 drops from its overshot position.

ES 2 334 643 T3 above the desired temperature TARGET_TEMP set by the user 67, towards the desired temperature TARGET_TEMP set by the user.

The compensation routine contemplated by this invention includes a compensation thread that can be called in any of the steps in Figs. 6-10 to modify any of the objective points of the method steps and the decision points established here (for example, TOSTAR_ESTABLECER, TOSTAR_LAT, TOSTAR_LBT, COCER_ESTABLECER, COCER_LAT and COCER_LBT). Modifying these values, generally upwards, prevents the actual temperature of the cooking cavity 12 of the oven 10 from falling too rapidly, since the cooling rate of the cooking cavity 12 corresponds to the difference between the current temperature of the oven. oven (such as the oven overflow temperature after the reheat cycle) and the desired target temperature, for which toast heating element 16 and bake heating element 18 will be inactive during that overshoot period.

The compensation method has been detailed in Fig. 11, and can be essentially referred to as a sub-process from any of the decision points and method steps to modify the values ​​considered above. The process begins in the compensation method in step 142, where the compensation method receives various parameters, as indicated in box 144.

Box 144 contains the parameters necessary for the compensation method of Fig. 11, including: TIMER representative of a clock count between zero seconds or minutes and the MAX_TIEMPO representative of the total time span of the compensation method of Fig. 11 Box 144 also contemplates a parameter titled MAX_COMP_FACTOR corresponding to the maximum amount that will be compensated for a particular temperature point. Finally, we proceed to the compensation method of Fig. 11 with a value of TEMP_ESTABLECER representative of, or that is an element of, one of the temperature values ​​indicated above, that is,

TEMP_ESTABLECER 6 &lt;

TOAST _ ESTABLECER, TOAST _ LA T, TOAST _ LBT COCER_ESTABLECER, COCERJ.AT and COCER_LBT

Once the parameters required in step 142 are obtained in the compensation method of Fig. 11, the process continues to step 146 in which the controller 34 determines the fraction of the total compensation cycle time (MAX_TIEMPO) elapsed during the cycle of the compensation method, calculating for this:

FRACTION = TIMER / MAX_TIEMPO

Processing then proceeds to step 148 where the maximum compensation factor MAX_COMP_ FACTOR is adjusted in accordance with the fraction of the compensation cycle time remaining, that is, (1 - FRACTION) as calculated in step 146. Thus An example of a MAX_COMP_FACTOR linear reduction formula that linearly reduces the amount of adjustment to MAX_COMP_FACTOR over the length of the compensation cycle, would be indicated by:

COMP_FACTOR = (1 - FRACTION). MAX_COMP_FACTOR

The process then proceeds to step 150, where the target set point for the TEMP_SET temperature value passed to the compensation method of Fig. 11, based on the COMP_FACTOR compensation factor calculated in step 148 according to whatever linear or non-linear function is desired or used in step 148 (a linear function has been illustrated, but in step 148 any non-linear function, or other, can be used without going beyond the scope of the invention). The new point set as the TEMP_ESTABLECER target is calculated as:

TEMP_ESTABLECER = TEMP_ESTABLECER x (1 + COMP_FACTOR).

The process then proceeds to step 152 where the compensation method of Fig. 11 returns the set TEMP_SET value calculated in step 150 at whatever decision point or step called the compensation method of Fig. eleven.

For example, if the compensation method in Fig. 11 employed a 48 minute timer, that is, MAX_TIME = 48 minutes or 2,880 seconds, and TIMER represents an integral value between 0 and MAX_TIME, controller 34 would also store a value for MAX_COMP_FACTOR such as 0.04 for a 4% upward adjustment at the TEMP_SET set point passed to the compensation method of Fig. 11. In linear compensation, the routine proposed in step 148 using the example of Fig. 11, calculated as a value between 0.00 and 1.00 based on the relationship of TIMER to MAX_TIME, would make

ES 2 334 643 T3 the COMP_FACTOR value would be a linear reduction value between MAX_COMP_FACTOR for TIMER = 0 and 0.00 for TIMER = MAX_TIEMPO. The TEMP_ESTABLECER value would then be multiplied by that calculated value to adjust up the TEMP_ESTABLECER value by the offset amount.

It has been verified that the exceeding of the desired target temperature TARGET_TEMP of the cavity for cooking 12, as well as the location of the temperature sensor 30 for roasting and the temperature sensor for cooking 32, closely adjacent to the heating element for roasting 16 and to the heating element to cook 18, creates this need so that the compensation algorithm of Fig. eleven control the temperature in the cook cavity 12 even more closely than contemplated in the steps of Figs. 6-10. This compensation method of Fig. 11 prevents the temperature variance or rate of temperature change in the cook cavity 12 from radically changing, and greatly reduces the temperature variance between the high temperature experienced and the low temperature experienced. for a particular desired target temperature TARGET_TEMP.