CA2318684C - Self-cleaning system for a cooking appliance - Google Patents
Self-cleaning system for a cooking appliance Download PDFInfo
- Publication number
- CA2318684C CA2318684C CA 2318684 CA2318684A CA2318684C CA 2318684 C CA2318684 C CA 2318684C CA 2318684 CA2318684 CA 2318684 CA 2318684 A CA2318684 A CA 2318684A CA 2318684 C CA2318684 C CA 2318684C
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- Canada
- Prior art keywords
- heating unit
- oven cavity
- heating
- air
- channel assembly
- Prior art date
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24C—DOMESTIC STOVES OR RANGES ; DETAILS OF DOMESTIC STOVES OR RANGES, OF GENERAL APPLICATION
- F24C14/00—Stoves or ranges having self-cleaning provisions, e.g. continuous catalytic cleaning or electrostatic cleaning
- F24C14/02—Stoves or ranges having self-cleaning provisions, e.g. continuous catalytic cleaning or electrostatic cleaning pyrolytic type
Abstract
A self-cleaning system is provided herein for a cooking appliance which is configured to operate in at least cleaning and convection cooking modes. The self-cleaning system includes an oven cavity with an air channel assembly extending about at least a portion of, and being in fluid communication with, the oven cavity. A blower element is provided for developing a flow of air within the air channel assembly and through the oven cavity. A
first heating unit is positioned in the air channel assembly for heating the flow of air. A
second heating unit is positioned in the oven cavity. Finally a controller is provided for regulating an activation and a deactivation state of each of the blower element and the first and second heating units during the cleaning mode.
first heating unit is positioned in the air channel assembly for heating the flow of air. A
second heating unit is positioned in the oven cavity. Finally a controller is provided for regulating an activation and a deactivation state of each of the blower element and the first and second heating units during the cleaning mode.
Description
SELF-CLEANING SYSTEM FOR A COOKIN(J APPLIANCE
TECHNICAL FIELD
The present invention pertains to the art of cooking appliances and, more particularly, to a system for cleaning a cooking appliance.
BACKGROUND ART
In the art of cooking appliances, it has been proposed heretofore to enable an appliance to operate in a self-cleaning mode. For example, in a conventional range having a cooking cavity which can be heated by one or more cooking elements arranged within the cooking cavity to perform at least baking and broiling functions, it is known to operate one or more of the cooking elements to perform a pyrolytic self-cleaning operation in order to cleanse the walls of the cavity from grease and other food soils developed during normal cooking operations. In such a cooking arrangement, the cooking elements used to perform the cleaning process are located entirely within the cooking cavity.
In addition, it is known to provide a catalytic self-cleaning oven. In such an arrangement, the walls of the oven are coated with a catalytic material which provides for self cleaning of the oven cavity during cooking operations. In performing any self-cleaning function, byproducts, including smoke, gases and other odorous fumes, are inherently produced. A typical oven cavity will be vented to permit the escape of these byproducts to the ambient surroundings. In some cases, a catalytic oxidation unit is provided in the vent to react with the flowing byproducts.
In still other self-cleaning arrangements, a co mbination of pyrolytic and catalytic cleaning is performed.
DESCRIPTION OF THE INVENTION
Particular concerns are raised in connection with the necessary operating time and byproduct elimination in a self cleaning convection oven which essentially relies on a heated flow of recirculating air for raising the temperature in acu oven cavity. Regardless of the fact that various self cleaning systems have been proposed in the art, there still exists a need for, and it is an object of a first aspect of the present invention to provide, an improved self cleaning system for a cooking appliance which maximizes the elimination of byproducts, while also minimizing the necessary operating time for the self cleaning mode.
In any event, there exists a particular need far, and it is an object of a second aspect of the present invention to provide, an improved self cleaning system for a convection cooking appliance.
The present invention provides, in a first broad aspect thereof, a system for self-cleaning an oven cavity of a cooking appliance including an air channel assembly which is dei°med by ducting extending about portions of the oven cavity for directing a recirculating flow of air into and out of the oven cavity. 'fhe overall system utilizes various heating elements, as well as a catalyst, to enhance the pre-heating of the oven cavity, efficiently eliminate developed smoke, odour and other byproducts, and effectively reduce the necessary cleaning cycle time for the appliance.
Thus, a first broad aspect of the present invention provides an improvement in a cooking appliance which is configured to operate in at least cleaning and convection cooking modes. The improvement resides in a self-cleaning system comprising an oven cavity with an air channel assembly extending about at least a portion of, and being in fluid communication with, the oven cavity. A blower element is provided for developing a flow of air within the air channel assembly and through the oven cavity. A first heating unit is positioned in the air channel assembly for heating the flow of air. A second heating unit is positioned in the oven cavity. A controller is provided for regulating an activation and a deactivation state of each of the blower element and the first and second heating units during the cleaning mode.
A second broad aspect of the present invention provided an improvement in a cooking appliance which is configured to operate in at least cleaning and convection cooking modes. The improvement resides in a self-cleaning system comprising an oven cavity with an air channel assembly extending about at least a portion of, and being in fluid communication with, the oven cavity . A blower element is provided for developing a flow of air within the air channel assembly and through the oven cavity. A first heating unit is positioned in the air channel assembly for heating the flow of air. A second heating unit is positioned in the oven cavity. A third heating unit is positioned in the air channel assembly for further heating the flow of air. A controller is provided for regulating an activation and _~_ a deactivation state of each of the blower element and the first and second heating units during the cleaning mode.
A third broad aspect of the present invention provides a method of performing a self cleaning operation for an oven cavity of a convection cooking appliance. The method includes providing an air channel assembly which extends about at least a portion of the oven cavity. The method includes developing a t7ow of air in the air channel assembly. The method includes providing a first heating; unit within the air channel assembly. The method includes activating the first heating unit therein to heat the flow of air.
The method includes directing the heated flow of air through the oven cavity. The method includes positioning a second heating unit within the oven cavity. The method finally includes activating the second heating unit, thereby further heating the oven cavity.
A fourth broad aspect of the present invention includes a method of performing a self-cleaning operation for an oven cavity of a convection cooking appliance.
The method includes providing an air channel assembly which extends about at least a portion of the ovc;n cavity. The method includes developing a flow of air in the air channel assembly. The method includes providing a first heating unit within the air channel assembly. The method includes activating the first heating unit, thereby to heat the t7ow of air.
The method includes sensing a temperature in the cooking appliance directly within the air channel assembly. The method includes directing the flow of air through the oven cavity. 'The method includes positioning a second heating unit within the oven cavity. The method includes activating the second heating unit, thereby further heating the oven cavity. The method finally includes regulating the activation and deactivatic:~n of at least one of the first and second heating units based on the sensed temperature.
In accordance with a preferred embodiment of an aspect c:~f the present invention, the convection cooking appliance includes first, second and third heating units which are individually controlled, along with a blower unit, in performing a self cleaning function for the appliance. The first and third heating units are disposed in the air channel assembly, while the second heating unit is positioned in the oven cavity. A controller is provided far regulating the activation and deactivation state of the various ec~mponents in a manner which preheats the oven cavity in a relatively short time period, while assuring that initially developed smoke, gases and other odorous fumes inherently produced as byproducts of a _3..
self-cleaning operation are effectively eliminated.
During the preheat phase of the cleaning mode, the controller initially activates the blower element in combination with each of the first and third heating units in the air channel assembly, with the developed t7ow of air through the oven cavity being directed to the catalyst for elimination of the byproducts. Following the preheat phase, at least the blower and the third heating element are deactivated and the second heating unit is activated to rapidly heat the oven cavity through a radiant heating operation.
A temperature sensor is linked to the controller to efficiently determine the optimum time to switch between the various heating sources for the oven cavity during the overall self cleaning operation.
DESCRIPTION OF THE FIGURES
In the accompanying drawings wherein like reference numerals refer to corresponding parts in the several views:
Figure 1 is a perspective, partial sectional view of a self-cleaning convention cooking appliance constructed in accordance with an embodiment of an aspect of the present invention;
Figure 2 is a cross-sectional side view of the cooking appliance of Figure l;
Figure 3 is a schematic side view, similar to that of Figure 2, of the cooking appliance;
Figure 4 is a block diagram illustrating a control arrangement used in the self cleaning system of an embodiment of an aspect of the present invention; and Figure 5 depicts a graph illustrating a time versus temperature curve followed in accordance with a preferred embodiment of an aspect of the prevent invention.
AT LEAST ONE MODE FOR CARRYING 01.1T THIINVENTION
With initial references to Figures 1-3, a cooking appliance: 1 is schematically shown in the form of a wall oven. Appliance 1 includes an oven cavity 5 which is generally defined by a bottom wall 8, a top wall 9, a rear wall 10 and a pair of side walls, one of which is indicated at 11. Oven cavity 5 also has associated therewith an access opening 13 for food items to be placed into, or withdrawn from, cavity 5. About access opening 13 is _4_ provided a frontal plate 16. In a manner known in the art, frontal plate 16 is adapted to be mounted against a substantially-vertical wall, e.g., in the kitchen of a residential home, and would have a door (not shown) which is pivotally attached thereto for selectively sealing off' access opening 13.
Extending generally along top, bottom and rear portions of cavity 5 is an air channel assembly 26 which is defined by ducting that leads into and out of cavity 5.
More specifically, air channel assembly 26 includes a lower air return section 29, an upper air delivery section 30 and a rear air transfer section 31. Lower air return section 29 is open into cavity 5 through a substantially-central return air outlet 33 which is formed in bottom 8. In the most preferred form of an embodiment of the present invention, return air outlet 33 is constituted by a generally-circular insert which is provided with various spaced holes (not shown). In a similar manner, upper air delivery section 3C) includes a discharge or delivery inlet 35 which is formed in top wall 9. Although only partially shown in Figure l, inlet 35 is also preferably constituted by a generally circular-shaped insert which i.s attached to the remainder of upper air delivery section 30 and which is provided with a plurality of holes 37.
As will become more fully evident below, the particular construction of cooking appliance 1 can significantly vary in accordance with aspects of the present invention.
More specifically, it is only important in accordance with aspects of the present invention that cooking appliance 1 include an air channel assembly, e. g. , that discussed above with reference to assembly 26, as well as a blower assembly, e.g., that generally indicated at 40, for use in generating a circulating flow of air through oven cavity 5.
Although not considered a part of the present invention, a preferred construction for oven cavity 5 and air channel assembly 26 can be found in lrl.S. Patent No. 6,373,037 issued April 16, 2002 to Maytag Corporation.
In the preferred embodiment of an aspect of the present invention shown, cooking appliance 1 constitutes an electric appliance ~rnd, more specifically, a combination convection, microwave and radiant cooking device. As shown in this figure, cooking appliance 1 is provided with an annular filter basket 46, having a multitude of circ:umferentially-spaced holes 47, which is positioned within lower air return section 29 and through which the air flowing from cavity 5 through return air outlet 33 is directed.
Arranged below filter basket 46 is a microwave generator unit 48 incorporating a magnetron (not specifically shown).
Encircling at least a portion of filter basket 46 is a first electric heating unit 52. First electric heating unit 52 is shown as constituted by a sheathed electric resistance heating element having upper and lower interconnected legs 53 and 54. 1~irst electric heating unit 52 is preferably provided to heat return air flowing from oven cavity 5, through outlet 33 and filter basket 46 prior to the air reaching a catalyst indicated at 57. In a manner known in the art, catalyst 57 functions to eliminate sm<ake and the like from the air stream. A
shown, catalyst 57 extends partially within a rotatable blower element 60 which forms part of blower assembly 40. Although blower element 60 can take various forms while performing the desired air flow generating function. blower element 60 preferably constitutes a centrifugal unit which is arranged at the junction crf lower air return section 29 and rear air transfer section 31. In general, blower element 60 is secured to a shaft member 62 that is rotatably mounted through a bearing assembly 64. Shaft member 62 also has attached thereto, for non-relative rotation, a sheave 66 which is adapted to receive a belt (not shown) for use in rotating blower element 60 through shaft member 62 in combination with an electric motor (also not shown). As illustrated, sheave 66 is preferably arranged within a housing extension 68 which projects from rear air transfer section 31.
Preferably mounted in upper air delivery section 30 adjacent to rear transfer section 31 is a second electric heating unit 7U that is preferably constituted by a bank of heating coils. Although not pertinent to aspects of the present invention, second heating unit 70 can be defined by a single electric coil that runs back and forth across upper air delivery section 30 or multiple, separately controllable coil elements. In any event, second heating unit 70 functions further to heat the air flowing through channel assembly 26 prior to the air reaching discharge inlet 35.
Also shown in this figure is a third electric heating unit 72 which, in a manner similar to first electric heating unit 52, is preferably constituted by a sheathed, resistance-type heating element. Third electric heating unit 72 preferably extends adjacent to top wall 9 and constitutes an additional heat source far cavity 5 of cc>oking appliance 1. The particular manner in which first, second and third electric heating units 52, 70 and 72 are utilized during operation of cooking appliance 1 for a cooking mode of operation is not considered to constitute part of aspects of the present invention. Instead these details can be found in U.S. patent No. 6,291,808 issued Sepkember 18, 2001 to Maytag Corporation.
As represented in Figure 4, each of blow~:~r assembly 40, microwave generator 48 and first, second arid third electric heating units 52, 70 and 72 are linked to an appliance controller or CPU 73. Appliance controller 73 also receives signals from operator input controls 74, as well as from a temperature sensor 75 which is preferably arranged in upper air delivery section 30, between heating unit 70 and delivery inlet 35. The present invention in a broad aspect thereof, is particularly directed ko the manner in which cooking appliance 1 is operated through a cleaning mode.
When an operator selects a cleaning mode through input controls 74, heating units 52 and 70 are initially activated, along with blower assembly 40, for preheating of oven cavity 5. At the same time, during this preheat phase, heating unit 72 is maintained deactivated.
This operational stage enables the oven cavity 5 to be heated in a substantially-exponential manner as represented by the portion A of tlae time/temperature curve shown in Figure 5.
This arrangement is designed to provide for a relatively-short preheat time period, while assuring that early stage self-clean byproducts will l7ow tc> the catalyst for effective elimination. That is, it is during this initial time period that suhstantial amounts of smoke, odours and other byproducts will be developed due to the burning off of grease and the like remaining in the oven cavity 5. By maintaining heating unit 72 deactivated, it has been found that an optimum preheat rate is established, with the temperature rise being based on the flow of heated air directed through the oven cavity 5.
When the temperature in oven cavity 5 reaches paint B oa the curve shown in Figure 5, which is generally in the order of 525 to 550°F as conveyed through temperature sensor 75, blower assembly 40 and heating unit 70 are deactivated, while heating unit 52 remains activated and heating unit 72 in oven cavity 5 is also activated, through controller 73. With blower element 40 deactivated, the air flowing through air channel assembly 26 is based on natural convection only. This switchover phase results in a short, generally-steady state time period, wherein the temperature within oven cavity 5 remains substantially-constant.
However, electric heating unit 72 is preferably a high wattage element which rapidly heats such that the temperature within oven cavity again rises exponentially, as represented by portion C in Figure 5, to a temperature preferably in the order of 930°
to 950°F. In fact, as _7_ clearly shown, portion C has an even higher associated slope than portion A.
With this overall control arrangement, the preheat phase is performed at a rate which assures that the developed byproducts are effectively eliminated and vented through catalyst 57, while the subsequent rapid heating of oven cavity 5 with heating unit 72 enables the time needed to perform the overall self-cleaning operation to be minimized.
Although described with respect to a preferred embodiment of the invention, it should be readily understood that various changes andlor modifications can be made to aspects of the present invention. For example, it should be noted that the various heating units, particularly heating units 52 rd 70, could be variable so as to be operated at increasing wattage ratings during the cleaning mode . In addition, blower element b0 could also be operated at variable speeds without departing from aspects of the present invention.
Furthermore, although heating element 70 is preferably constituted by a single bank of open coils, multiple sets of coils could be utilized and individually controlled.
_g_
TECHNICAL FIELD
The present invention pertains to the art of cooking appliances and, more particularly, to a system for cleaning a cooking appliance.
BACKGROUND ART
In the art of cooking appliances, it has been proposed heretofore to enable an appliance to operate in a self-cleaning mode. For example, in a conventional range having a cooking cavity which can be heated by one or more cooking elements arranged within the cooking cavity to perform at least baking and broiling functions, it is known to operate one or more of the cooking elements to perform a pyrolytic self-cleaning operation in order to cleanse the walls of the cavity from grease and other food soils developed during normal cooking operations. In such a cooking arrangement, the cooking elements used to perform the cleaning process are located entirely within the cooking cavity.
In addition, it is known to provide a catalytic self-cleaning oven. In such an arrangement, the walls of the oven are coated with a catalytic material which provides for self cleaning of the oven cavity during cooking operations. In performing any self-cleaning function, byproducts, including smoke, gases and other odorous fumes, are inherently produced. A typical oven cavity will be vented to permit the escape of these byproducts to the ambient surroundings. In some cases, a catalytic oxidation unit is provided in the vent to react with the flowing byproducts.
In still other self-cleaning arrangements, a co mbination of pyrolytic and catalytic cleaning is performed.
DESCRIPTION OF THE INVENTION
Particular concerns are raised in connection with the necessary operating time and byproduct elimination in a self cleaning convection oven which essentially relies on a heated flow of recirculating air for raising the temperature in acu oven cavity. Regardless of the fact that various self cleaning systems have been proposed in the art, there still exists a need for, and it is an object of a first aspect of the present invention to provide, an improved self cleaning system for a cooking appliance which maximizes the elimination of byproducts, while also minimizing the necessary operating time for the self cleaning mode.
In any event, there exists a particular need far, and it is an object of a second aspect of the present invention to provide, an improved self cleaning system for a convection cooking appliance.
The present invention provides, in a first broad aspect thereof, a system for self-cleaning an oven cavity of a cooking appliance including an air channel assembly which is dei°med by ducting extending about portions of the oven cavity for directing a recirculating flow of air into and out of the oven cavity. 'fhe overall system utilizes various heating elements, as well as a catalyst, to enhance the pre-heating of the oven cavity, efficiently eliminate developed smoke, odour and other byproducts, and effectively reduce the necessary cleaning cycle time for the appliance.
Thus, a first broad aspect of the present invention provides an improvement in a cooking appliance which is configured to operate in at least cleaning and convection cooking modes. The improvement resides in a self-cleaning system comprising an oven cavity with an air channel assembly extending about at least a portion of, and being in fluid communication with, the oven cavity. A blower element is provided for developing a flow of air within the air channel assembly and through the oven cavity. A first heating unit is positioned in the air channel assembly for heating the flow of air. A second heating unit is positioned in the oven cavity. A controller is provided for regulating an activation and a deactivation state of each of the blower element and the first and second heating units during the cleaning mode.
A second broad aspect of the present invention provided an improvement in a cooking appliance which is configured to operate in at least cleaning and convection cooking modes. The improvement resides in a self-cleaning system comprising an oven cavity with an air channel assembly extending about at least a portion of, and being in fluid communication with, the oven cavity . A blower element is provided for developing a flow of air within the air channel assembly and through the oven cavity. A first heating unit is positioned in the air channel assembly for heating the flow of air. A second heating unit is positioned in the oven cavity. A third heating unit is positioned in the air channel assembly for further heating the flow of air. A controller is provided for regulating an activation and _~_ a deactivation state of each of the blower element and the first and second heating units during the cleaning mode.
A third broad aspect of the present invention provides a method of performing a self cleaning operation for an oven cavity of a convection cooking appliance. The method includes providing an air channel assembly which extends about at least a portion of the oven cavity. The method includes developing a t7ow of air in the air channel assembly. The method includes providing a first heating; unit within the air channel assembly. The method includes activating the first heating unit therein to heat the flow of air.
The method includes directing the heated flow of air through the oven cavity. The method includes positioning a second heating unit within the oven cavity. The method finally includes activating the second heating unit, thereby further heating the oven cavity.
A fourth broad aspect of the present invention includes a method of performing a self-cleaning operation for an oven cavity of a convection cooking appliance.
The method includes providing an air channel assembly which extends about at least a portion of the ovc;n cavity. The method includes developing a flow of air in the air channel assembly. The method includes providing a first heating unit within the air channel assembly. The method includes activating the first heating unit, thereby to heat the t7ow of air.
The method includes sensing a temperature in the cooking appliance directly within the air channel assembly. The method includes directing the flow of air through the oven cavity. 'The method includes positioning a second heating unit within the oven cavity. The method includes activating the second heating unit, thereby further heating the oven cavity. The method finally includes regulating the activation and deactivatic:~n of at least one of the first and second heating units based on the sensed temperature.
In accordance with a preferred embodiment of an aspect c:~f the present invention, the convection cooking appliance includes first, second and third heating units which are individually controlled, along with a blower unit, in performing a self cleaning function for the appliance. The first and third heating units are disposed in the air channel assembly, while the second heating unit is positioned in the oven cavity. A controller is provided far regulating the activation and deactivation state of the various ec~mponents in a manner which preheats the oven cavity in a relatively short time period, while assuring that initially developed smoke, gases and other odorous fumes inherently produced as byproducts of a _3..
self-cleaning operation are effectively eliminated.
During the preheat phase of the cleaning mode, the controller initially activates the blower element in combination with each of the first and third heating units in the air channel assembly, with the developed t7ow of air through the oven cavity being directed to the catalyst for elimination of the byproducts. Following the preheat phase, at least the blower and the third heating element are deactivated and the second heating unit is activated to rapidly heat the oven cavity through a radiant heating operation.
A temperature sensor is linked to the controller to efficiently determine the optimum time to switch between the various heating sources for the oven cavity during the overall self cleaning operation.
DESCRIPTION OF THE FIGURES
In the accompanying drawings wherein like reference numerals refer to corresponding parts in the several views:
Figure 1 is a perspective, partial sectional view of a self-cleaning convention cooking appliance constructed in accordance with an embodiment of an aspect of the present invention;
Figure 2 is a cross-sectional side view of the cooking appliance of Figure l;
Figure 3 is a schematic side view, similar to that of Figure 2, of the cooking appliance;
Figure 4 is a block diagram illustrating a control arrangement used in the self cleaning system of an embodiment of an aspect of the present invention; and Figure 5 depicts a graph illustrating a time versus temperature curve followed in accordance with a preferred embodiment of an aspect of the prevent invention.
AT LEAST ONE MODE FOR CARRYING 01.1T THIINVENTION
With initial references to Figures 1-3, a cooking appliance: 1 is schematically shown in the form of a wall oven. Appliance 1 includes an oven cavity 5 which is generally defined by a bottom wall 8, a top wall 9, a rear wall 10 and a pair of side walls, one of which is indicated at 11. Oven cavity 5 also has associated therewith an access opening 13 for food items to be placed into, or withdrawn from, cavity 5. About access opening 13 is _4_ provided a frontal plate 16. In a manner known in the art, frontal plate 16 is adapted to be mounted against a substantially-vertical wall, e.g., in the kitchen of a residential home, and would have a door (not shown) which is pivotally attached thereto for selectively sealing off' access opening 13.
Extending generally along top, bottom and rear portions of cavity 5 is an air channel assembly 26 which is defined by ducting that leads into and out of cavity 5.
More specifically, air channel assembly 26 includes a lower air return section 29, an upper air delivery section 30 and a rear air transfer section 31. Lower air return section 29 is open into cavity 5 through a substantially-central return air outlet 33 which is formed in bottom 8. In the most preferred form of an embodiment of the present invention, return air outlet 33 is constituted by a generally-circular insert which is provided with various spaced holes (not shown). In a similar manner, upper air delivery section 3C) includes a discharge or delivery inlet 35 which is formed in top wall 9. Although only partially shown in Figure l, inlet 35 is also preferably constituted by a generally circular-shaped insert which i.s attached to the remainder of upper air delivery section 30 and which is provided with a plurality of holes 37.
As will become more fully evident below, the particular construction of cooking appliance 1 can significantly vary in accordance with aspects of the present invention.
More specifically, it is only important in accordance with aspects of the present invention that cooking appliance 1 include an air channel assembly, e. g. , that discussed above with reference to assembly 26, as well as a blower assembly, e.g., that generally indicated at 40, for use in generating a circulating flow of air through oven cavity 5.
Although not considered a part of the present invention, a preferred construction for oven cavity 5 and air channel assembly 26 can be found in lrl.S. Patent No. 6,373,037 issued April 16, 2002 to Maytag Corporation.
In the preferred embodiment of an aspect of the present invention shown, cooking appliance 1 constitutes an electric appliance ~rnd, more specifically, a combination convection, microwave and radiant cooking device. As shown in this figure, cooking appliance 1 is provided with an annular filter basket 46, having a multitude of circ:umferentially-spaced holes 47, which is positioned within lower air return section 29 and through which the air flowing from cavity 5 through return air outlet 33 is directed.
Arranged below filter basket 46 is a microwave generator unit 48 incorporating a magnetron (not specifically shown).
Encircling at least a portion of filter basket 46 is a first electric heating unit 52. First electric heating unit 52 is shown as constituted by a sheathed electric resistance heating element having upper and lower interconnected legs 53 and 54. 1~irst electric heating unit 52 is preferably provided to heat return air flowing from oven cavity 5, through outlet 33 and filter basket 46 prior to the air reaching a catalyst indicated at 57. In a manner known in the art, catalyst 57 functions to eliminate sm<ake and the like from the air stream. A
shown, catalyst 57 extends partially within a rotatable blower element 60 which forms part of blower assembly 40. Although blower element 60 can take various forms while performing the desired air flow generating function. blower element 60 preferably constitutes a centrifugal unit which is arranged at the junction crf lower air return section 29 and rear air transfer section 31. In general, blower element 60 is secured to a shaft member 62 that is rotatably mounted through a bearing assembly 64. Shaft member 62 also has attached thereto, for non-relative rotation, a sheave 66 which is adapted to receive a belt (not shown) for use in rotating blower element 60 through shaft member 62 in combination with an electric motor (also not shown). As illustrated, sheave 66 is preferably arranged within a housing extension 68 which projects from rear air transfer section 31.
Preferably mounted in upper air delivery section 30 adjacent to rear transfer section 31 is a second electric heating unit 7U that is preferably constituted by a bank of heating coils. Although not pertinent to aspects of the present invention, second heating unit 70 can be defined by a single electric coil that runs back and forth across upper air delivery section 30 or multiple, separately controllable coil elements. In any event, second heating unit 70 functions further to heat the air flowing through channel assembly 26 prior to the air reaching discharge inlet 35.
Also shown in this figure is a third electric heating unit 72 which, in a manner similar to first electric heating unit 52, is preferably constituted by a sheathed, resistance-type heating element. Third electric heating unit 72 preferably extends adjacent to top wall 9 and constitutes an additional heat source far cavity 5 of cc>oking appliance 1. The particular manner in which first, second and third electric heating units 52, 70 and 72 are utilized during operation of cooking appliance 1 for a cooking mode of operation is not considered to constitute part of aspects of the present invention. Instead these details can be found in U.S. patent No. 6,291,808 issued Sepkember 18, 2001 to Maytag Corporation.
As represented in Figure 4, each of blow~:~r assembly 40, microwave generator 48 and first, second arid third electric heating units 52, 70 and 72 are linked to an appliance controller or CPU 73. Appliance controller 73 also receives signals from operator input controls 74, as well as from a temperature sensor 75 which is preferably arranged in upper air delivery section 30, between heating unit 70 and delivery inlet 35. The present invention in a broad aspect thereof, is particularly directed ko the manner in which cooking appliance 1 is operated through a cleaning mode.
When an operator selects a cleaning mode through input controls 74, heating units 52 and 70 are initially activated, along with blower assembly 40, for preheating of oven cavity 5. At the same time, during this preheat phase, heating unit 72 is maintained deactivated.
This operational stage enables the oven cavity 5 to be heated in a substantially-exponential manner as represented by the portion A of tlae time/temperature curve shown in Figure 5.
This arrangement is designed to provide for a relatively-short preheat time period, while assuring that early stage self-clean byproducts will l7ow tc> the catalyst for effective elimination. That is, it is during this initial time period that suhstantial amounts of smoke, odours and other byproducts will be developed due to the burning off of grease and the like remaining in the oven cavity 5. By maintaining heating unit 72 deactivated, it has been found that an optimum preheat rate is established, with the temperature rise being based on the flow of heated air directed through the oven cavity 5.
When the temperature in oven cavity 5 reaches paint B oa the curve shown in Figure 5, which is generally in the order of 525 to 550°F as conveyed through temperature sensor 75, blower assembly 40 and heating unit 70 are deactivated, while heating unit 52 remains activated and heating unit 72 in oven cavity 5 is also activated, through controller 73. With blower element 40 deactivated, the air flowing through air channel assembly 26 is based on natural convection only. This switchover phase results in a short, generally-steady state time period, wherein the temperature within oven cavity 5 remains substantially-constant.
However, electric heating unit 72 is preferably a high wattage element which rapidly heats such that the temperature within oven cavity again rises exponentially, as represented by portion C in Figure 5, to a temperature preferably in the order of 930°
to 950°F. In fact, as _7_ clearly shown, portion C has an even higher associated slope than portion A.
With this overall control arrangement, the preheat phase is performed at a rate which assures that the developed byproducts are effectively eliminated and vented through catalyst 57, while the subsequent rapid heating of oven cavity 5 with heating unit 72 enables the time needed to perform the overall self-cleaning operation to be minimized.
Although described with respect to a preferred embodiment of the invention, it should be readily understood that various changes andlor modifications can be made to aspects of the present invention. For example, it should be noted that the various heating units, particularly heating units 52 rd 70, could be variable so as to be operated at increasing wattage ratings during the cleaning mode . In addition, blower element b0 could also be operated at variable speeds without departing from aspects of the present invention.
Furthermore, although heating element 70 is preferably constituted by a single bank of open coils, multiple sets of coils could be utilized and individually controlled.
_g_
Claims (20)
1. In a cooking appliance which is configured to operate in at least cleaning and convection cooking modes, a self-cleaning system comprising:
an oven cavity;
an air channel assembly extending about at least a portion of, and being in fluid communication with, said oven cavity;
a blower element for developing a flow of air within said air channel assembly and through said oven cavity;
a first heating unit which is position in said air channel assembly for heating said flow of air;
a second heating unit which is position in said oven cavity; and a controller for regulating an activation and a deactivation state of each of said blower element and said first and second heating units during said cleaning mode.
an oven cavity;
an air channel assembly extending about at least a portion of, and being in fluid communication with, said oven cavity;
a blower element for developing a flow of air within said air channel assembly and through said oven cavity;
a first heating unit which is position in said air channel assembly for heating said flow of air;
a second heating unit which is position in said oven cavity; and a controller for regulating an activation and a deactivation state of each of said blower element and said first and second heating units during said cleaning mode.
2. The self-cleaning system according to claim 1, wherein said controller is configured initially to activate said blower element and said first heating unit, while maintaining said second heating unit deactivated, during an oven preheat phase of said cleaning mode.
3. The self-cleaning system according to claim 2, wherein said controller is configured to maintain said first heating unit activated and is configured further to activate said second heating unit following said preheat phase.
4. In a cooking appliance which is configured to operate in at least cleaning and convection cooking modes, a self-cleaning system comprising:
an oven cavity;
an air channel assembly extending about at least a portion of, and being in fluid communication with, said oven cavity;
a blower element for developing a flow of air within the air channel assembly and through the oven cavity;
a first heating unit which is position in said air channel assembly for heating the flow of air;
a second heating unit which is positioned in said oven cavity;
a third heating unit which is positioned in said air channel assembly for further heating said flow of air; and a controller for regulating an activation and a deactivation state of each of said blower element and said first, second and third heating units, with at least the first and second heating units being regulated during said cleaning mode.
an oven cavity;
an air channel assembly extending about at least a portion of, and being in fluid communication with, said oven cavity;
a blower element for developing a flow of air within the air channel assembly and through the oven cavity;
a first heating unit which is position in said air channel assembly for heating the flow of air;
a second heating unit which is positioned in said oven cavity;
a third heating unit which is positioned in said air channel assembly for further heating said flow of air; and a controller for regulating an activation and a deactivation state of each of said blower element and said first, second and third heating units, with at least the first and second heating units being regulated during said cleaning mode.
5. The self-cleaning system according to claim 4, further comprising:
a catalyst which is arranged in said air channel assembly.
a catalyst which is arranged in said air channel assembly.
6. The self-cleaning system according to claim 5, wherein said catalyst is located between said first heating unit and said blower element.
7. The self-cleaning system according to claim 5, wherein said first heating element is located directly upstream of said catalyst.
8. The self-cleaning system according to claim 5, claim 6 or claim 7, wherein said catalyst is configured to operate throughout the entire said cleaning mode.
9. The self-cleaning system according to any one of claims 4 to 8, wherein said first and second heating units comprise sheathed, electric resistance type heating elements.
10. The self-cleaning system according to any one of claims 1 to 9, further comprising:
a temperature sensor for sensing an operating temperature of said cooking appliance during said cleaning mode.
a temperature sensor for sensing an operating temperature of said cooking appliance during said cleaning mode.
11. The self-cleaning system according to claim 10, wherein said temperature sensor is arranged in said air channel assembly.
12. A method of performing a self-cleaning operation for an oven cavity of a convection cooking appliance comprising:
providing an air channel assembly which extends about at least a portion of the oven cavity;
developing a flow of air in said air channel assembly;
providing a first heating unit within said air channel assembly;
activating said first heating unit therein to heat said flow of air;
directing said heated flow of air through said oven cavity;
positioning a second heating unit within said oven cavity; and activating said second heating unit, thereby further heating said oven cavity.
providing an air channel assembly which extends about at least a portion of the oven cavity;
developing a flow of air in said air channel assembly;
providing a first heating unit within said air channel assembly;
activating said first heating unit therein to heat said flow of air;
directing said heated flow of air through said oven cavity;
positioning a second heating unit within said oven cavity; and activating said second heating unit, thereby further heating said oven cavity.
13. The method according to claim 12, further comprising:
maintaining the second heating unit deactivated during a preheat phase of said self-cleaning operation.
maintaining the second heating unit deactivated during a preheat phase of said self-cleaning operation.
14. The method according to claim 13, further comprising:
positioning a third heating unit, within said air channel assembly; and activating said third heating unit during said preheat phase.
positioning a third heating unit, within said air channel assembly; and activating said third heating unit during said preheat phase.
15. The method according to claim 12, claim 13 or claim 14, further comprising:
maintaining the said first heating unit activated following said preheat phase.
maintaining the said first heating unit activated following said preheat phase.
16. The method according to any one of claims 12 to 15, further comprising:
heating said oven cavity, following said preheat phase, solely with said first and second heating units.
heating said oven cavity, following said preheat phase, solely with said first and second heating units.
17. The method according to any one of claims 12 to 16, further comprising:
sensing a temperature in said cooking appliance directly within said air channel assembly; and regulating the activation and deactivation of the first, second and third heating units based on the sensed temperature.
sensing a temperature in said cooking appliance directly within said air channel assembly; and regulating the activation and deactivation of the first, second and third heating units based on the sensed temperature.
18. The method according to any one of claims 12 to 17, further comprising:
positioning a catalyst within the air channel assembly; and directing the flow of air, exiting the oven cavity, through said catalyst.
positioning a catalyst within the air channel assembly; and directing the flow of air, exiting the oven cavity, through said catalyst.
19. The method according to claim 18, further comprising:
heating said catalyst with said first heating unit.
heating said catalyst with said first heating unit.
20. A method of performing a self-cleaning operation for an oven cavity of a convection cooking appliance, said method comprising:
providing an air channel assembly which extends about at least a portion of the oven cavity;
developing a flow of air in said air channel assembly;
providing a first heating unit within said air channel assembly;
activating said first heating unit, thereby to heat the flow of air;
sensing a temperature in said cooking appliance directly within said air channel assembly;
directing said flow of air through said oven cavity;
positioning a second heating unit within the oven cavity;
activating said second heating unit, thereby further heating said oven cavity;
and regulating the activation and deactivation of at least one of said first and second heating units based on said sensed temperature.
providing an air channel assembly which extends about at least a portion of the oven cavity;
developing a flow of air in said air channel assembly;
providing a first heating unit within said air channel assembly;
activating said first heating unit, thereby to heat the flow of air;
sensing a temperature in said cooking appliance directly within said air channel assembly;
directing said flow of air through said oven cavity;
positioning a second heating unit within the oven cavity;
activating said second heating unit, thereby further heating said oven cavity;
and regulating the activation and deactivation of at least one of said first and second heating units based on said sensed temperature.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US15322699P | 1999-09-13 | 1999-09-13 | |
| US60/153,226 | 1999-09-13 | ||
| US09/650,416 | 2000-08-29 | ||
| US09/650,416 US6316749B1 (en) | 2000-08-29 | 2000-08-29 | Self-cleaning system for a cooking appliance |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2318684A1 CA2318684A1 (en) | 2001-03-13 |
| CA2318684C true CA2318684C (en) | 2006-11-14 |
Family
ID=26850316
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2318684 Expired - Fee Related CA2318684C (en) | 1999-09-13 | 2000-09-13 | Self-cleaning system for a cooking appliance |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2318684C (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3864970A4 (en) | 2018-10-11 | 2022-09-14 | Stronghold Technology, Inc. | Roasting apparatus and control method therefor |
-
2000
- 2000-09-13 CA CA 2318684 patent/CA2318684C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2318684A1 (en) | 2001-03-13 |
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| MKLA | Lapsed |