CA2204795C - Warmer drawer for a cooking range - Google Patents
Warmer drawer for a cooking range Download PDFInfo
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- CA2204795C CA2204795C CA002204795A CA2204795A CA2204795C CA 2204795 C CA2204795 C CA 2204795C CA 002204795 A CA002204795 A CA 002204795A CA 2204795 A CA2204795 A CA 2204795A CA 2204795 C CA2204795 C CA 2204795C
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- temperature
- heating chamber
- heating
- heating element
- warmer
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Classifications
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- 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
- F24C15/00—Details
- F24C15/18—Arrangement of compartments additional to cooking compartments, e.g. for warming or for storing utensils or fuel containers; Arrangement of additional heating or cooking apparatus, e.g. grills
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Electric Stoves And Ranges (AREA)
Abstract
A warming drawer for a domestic range which is disposed within a heating chamber located relatively beneath the oven. The heating chamber is surrounded by a series of panels, and has a heating element disposed therein. The heating element is energized in accordance with a user-determined duty cycle such that temperature within the heating chamber is maintained between a predetermined minimum temperature and a predetermined maximum temperature. The range of temperatures between the predetermined minimum and predetermined maximum correspond to a range of desired food serving temperatures at the warmer drawer.
Description
b HACRGROUND OF THE INVENTION
8 The present invention pertains to domestic cooking 9 ranges and, more particularly, to domestic coo)cing ranges to having a warming drawer adapted to receive and maintain 11 cooked hot food at an above-ambient temperature.
13 Domestic cooking ranges traditionally include an open 14 space relatively beneath the oven which slidably receives a storage drawer in which the user may store various 1.6 articles, such as cooking pots and/or pans. As such, the 17 conventional or prior art drawer is only useful for storage 1.8 purposes, and could not be used to heat or warm food.
19 The space occupied by the storage drawer has also, in the past, been used as a broiling cavity which receives a 21 broiling tray. A broiling element is located relatively 2.2 above the broiling tray. The broiling element is operated 23 at high temperatures as required to accomplish the broiling 24 function.
The prior art references which include a broiling 26 element do not control energization of the broiling element 27 to only warm food contained on the broiling tray. Rather, 28 the broiling element is typically operated exclusively at 29 full power, as required for broiling. Due to the high-energy or high-heat output of the broiling element, maintaining food at an above-ambient temperature for warming purposes, but still low enough so that further cooking does not occur, is not possible.
Therefore, there exists a need in the art for a cooking applicant which provides a warmer drawer in which heating or warming of food is permitted. There also exists a need in the art for a warming device wherein the temperature of the food within the device is controlled such that further cooking of the food, which may degrade the food quality, does not occur.
SUMMARY OF THE INVENTION
In a first aspect, the present invention provides a cooking appliance, comprising a cabinet, a lower heating chamber adapted to receive a food receiving member, a heating element disposed within said heating chamber, means for controlling said heating element such that a temperature within said heating chamber is maintained between a predetermined minimum temperature and a predetermined maximum temperature corresponding to a range of desired food serving temperature, wherein said controlling means comprise a temperature sensor and an infinite switch.
In another aspect, the present invention provides a method for controlling a warmer drawer heating element to maintain a temperature within a heating chamber between a predetermined maximum and a predetermined minimum, said warmer drawer heating element being disposed within said heating chamber, comprising the steps of: moving a heater control switch from an off position to a user-selected position, said user selected position corresponding to a duty cycle of heater element operation; energizing said heater element at full power; sensing the temperature within said heating chamber; terminating full power energization of said heater element at said predetermined maximum temperature; energizing said heater element at said predetermined duty cycle; terminating energization of said heater element at said predetermined duty cycle at said predetermined minimum temperature; energizing said heater element at full power; and terminating full power energization of said heater element at said predetermined maximum temperature; resuming energization of said heater element at said predetermined duty cycle.
In yet another aspect, the present invention provides a cooking appliance, comprising: a cabinet; an oven wrapper disposed within said cabinet, said oven wrapper having a generally inverted u-shape including a pair of lateral side walls; a warmer liner, comprising: a liner top wall disposed generally between said lateral side walls; a liner bottom wall disposed generally between said lateral side walls, wherein said liner top wall and bottom wall cooperate with said lateral side walls to define a heating chamber; a warmer drawer adapted to be received within said heating chamber; a heating element secured to said liner bottom wall relatively beneath said warmer drawer; a temperature sensor disposed within said heating chamber; and a control device operable to control energization of said heating element to maintain the temperature within said heating chamber between a predetermined minimum temperature and a predetermined maximum temperature corresponding to a range of desired food serving temperatures, wherein said control device comprises a user-adjustable infinite switch.
In a further aspect, the present invention provides a method for controlling an electrical warmer drawer heating element to maintain a temperature within a lower heating chamber, comprising steps of: providing a range for placement on a floor, providing a cabinet to said range, providing an oven wrapper disposed within said cabinet. and at least partially defining an oven chamber, providing the lower heating chamber relatively beneath said oven chamber, providing a fixed panel defining a lower extent of the heating chamber, providing the electrical heating element within said heating chamber, adjacent to the panel, providing the warmer drawer slidably mounted in the lower heating chamber, above the heating element and the panel, providing a temperature sensor disposed within said heating chamber and operable to sense temperature within said heating chamber, and providing controlling means for controlling said heating element such that a temperature within said heating chamber is maintained between a predetermined minimum temperature and a predetermined maximum temperature corresponding to a range of desired food serving temperatures; moving a heater control switch from an off position to a user-selected position, said user selected position corresponding to a duty cycle of heater element operation; energizing said heater element at full power;
sensing the temperature within said heating chamber using the temperature sensor; terminating full power energization of said heater element at said predetermined maximum temperature; energizing said heater element at said predetermined duty cycle.
BRIEF DESCRIPTION OF THE DRAWINGS
Features of the present invention will be apparent with reference to the following description and drawings, wherein:
FIG. 1 is a perspective view of a cooking range with a food warmer in a fully extended position;
FIG. 2 is a rear perspective view of a food warmer drawer according to the present invention;
FIG. 3 is a front elevational view of a lower portion of the cooking range shown in FIG. 1, with the food warmer drawer removed therefrom;
FIG. 4a, 4b and 4c, are respectively, a front elevational view, a top plan view, and a side elevational -3a-view of a front heat shield panel or grate according to the present invention;
FIG. 4d is a cross sectional view of the front heat shield as seen along line 4d-4d of FIG. 4a;
FIG. 5a, 5b and 5c are, respectively, a front elevational view, a top plan view, and a side elevational view of a rear heat shield panel according to the present invention;
-3b-1 FIG. 6a, Gb, and Gc are, respectively, a top plan 2 view, a front elevational view, and a side elevational view 3 of a lower heat shield panel according to the present 4 invention;
FIG. 7a, 7b, and 7c are, respectively, a bottom plan 6 view, a front elevational view, and a side elevational view 7 of ~n~upper heat shield panel according to the present 8 invention;
9 'FIGS. 8a, 8b, and 8c are, respectively, a front elevational view, a top plan view, and a side elevational 11 view of a temperature sensor mounting brac)cet according to 12 the present invention;
13 FIGS. 9a, 9b, and 9c are, respectively, a front 14 elevational view, a top plan view, and a side elevational view of a warmer drawer temperature sensor according to the 16 present invention;
17 FIG. 10 is a side elevational view of a warmer drawer 18 glide assembly according to the present invention;
19 FIG. 11 is an end elevational view of the warmer drawer glide assembly shown in FIG. 10.
21 FIG. 12 is top plan view of a heating element 22 according to the present invention;
23 FIG. 13 is a perspective view of a heating element 24 mounting clip according to the present invention;
FIG. 14 is a front elevational view of an oven chassis 26 wrapper according to the present invention; and, 27 FIG. 15 is a schematic diagram illustrating a control 28 circuit for the warmer drawer heating element.
It should be noted that in the detailed description 31 which follows, identical components have the same reference 32 numeral, regardless are shown in different of whether they 33 embodiments of the present invention.
It should also be 34 noted that, in order to clearly and concisely disclose the 1 present invention, the drawings may not necessarily be to 2 scale and certain features of the invention may be shown in 3 somewhat schematic form.
4 With reference to FIG. 1, a household range 20 incorporating the present invention is illustrated. The 6 range includes a cabinet to which an oven door 22 is 7 secured so as to permit pivotal movement of the door about 8 its bottom edge. The cabinet includes a top panel which 9 includes surface heating elements (not shown). A control panel 24 extends upwardly from adjacent a rear portion of 11 the top panel, and includes a plurality of control devices, 12 such as dials, switches, buttons, and/or knobs.
13 The control devices provided by the control panel 14 include a warmer drawer heater control switch 26, and associated indicator light 28. Preferably, the warmer 16 drawer heater control switch 26 is rotatably mounted to the 17 control panel, and is movable in a push-and-turn fashion to 18 any user-selected position between an off position, and a 19 high heat position. More preferably, the warmer drawer heater control switch 26 is an infinite switch wherein the 21 duty cycle (ratio of heater on-time to heater on-time plus 22 heater off-time) varies from zero, when the switch is set 23 to the off position, to one when the switch 26 is set to 24 the high position.
As will be described more fully hereafter, rotation of 26 the'w~rmer drawer heater control switch 26 between the 27 various user-selected positions varies the duty cycle of a 28 warmer drawer heating element 32. It is believed that 29 operation of infinite switches is well known to one skilled in the art and, therefore, will not be further discussed 31 hereinafter.
32 With reference to FIG. 2, the warmer drawer 34 33 according to the present invention is illustrated. The 34 warmer drawer preferably includes a pair of lateral side walls 36, a rear wall 38, a bottom wall 40, and a front 36 wall 42 which cooperate to define a receptacle adapted to 37 receive food stuffs to be maintained at an acceptable ' CA 02204795 1997-OS-08 1 above-ambient serving temperature.
2 The front wall 42 includes a front panel 44 from which 3 a handle extends (FIG. 1). Each of the lateral side walls 4 36 had a first portion 47 of a glide assembly 48 secured thereto, as will be described more fully hereafter.
8 The present invention pertains to domestic cooking 9 ranges and, more particularly, to domestic coo)cing ranges to having a warming drawer adapted to receive and maintain 11 cooked hot food at an above-ambient temperature.
13 Domestic cooking ranges traditionally include an open 14 space relatively beneath the oven which slidably receives a storage drawer in which the user may store various 1.6 articles, such as cooking pots and/or pans. As such, the 17 conventional or prior art drawer is only useful for storage 1.8 purposes, and could not be used to heat or warm food.
19 The space occupied by the storage drawer has also, in the past, been used as a broiling cavity which receives a 21 broiling tray. A broiling element is located relatively 2.2 above the broiling tray. The broiling element is operated 23 at high temperatures as required to accomplish the broiling 24 function.
The prior art references which include a broiling 26 element do not control energization of the broiling element 27 to only warm food contained on the broiling tray. Rather, 28 the broiling element is typically operated exclusively at 29 full power, as required for broiling. Due to the high-energy or high-heat output of the broiling element, maintaining food at an above-ambient temperature for warming purposes, but still low enough so that further cooking does not occur, is not possible.
Therefore, there exists a need in the art for a cooking applicant which provides a warmer drawer in which heating or warming of food is permitted. There also exists a need in the art for a warming device wherein the temperature of the food within the device is controlled such that further cooking of the food, which may degrade the food quality, does not occur.
SUMMARY OF THE INVENTION
In a first aspect, the present invention provides a cooking appliance, comprising a cabinet, a lower heating chamber adapted to receive a food receiving member, a heating element disposed within said heating chamber, means for controlling said heating element such that a temperature within said heating chamber is maintained between a predetermined minimum temperature and a predetermined maximum temperature corresponding to a range of desired food serving temperature, wherein said controlling means comprise a temperature sensor and an infinite switch.
In another aspect, the present invention provides a method for controlling a warmer drawer heating element to maintain a temperature within a heating chamber between a predetermined maximum and a predetermined minimum, said warmer drawer heating element being disposed within said heating chamber, comprising the steps of: moving a heater control switch from an off position to a user-selected position, said user selected position corresponding to a duty cycle of heater element operation; energizing said heater element at full power; sensing the temperature within said heating chamber; terminating full power energization of said heater element at said predetermined maximum temperature; energizing said heater element at said predetermined duty cycle; terminating energization of said heater element at said predetermined duty cycle at said predetermined minimum temperature; energizing said heater element at full power; and terminating full power energization of said heater element at said predetermined maximum temperature; resuming energization of said heater element at said predetermined duty cycle.
In yet another aspect, the present invention provides a cooking appliance, comprising: a cabinet; an oven wrapper disposed within said cabinet, said oven wrapper having a generally inverted u-shape including a pair of lateral side walls; a warmer liner, comprising: a liner top wall disposed generally between said lateral side walls; a liner bottom wall disposed generally between said lateral side walls, wherein said liner top wall and bottom wall cooperate with said lateral side walls to define a heating chamber; a warmer drawer adapted to be received within said heating chamber; a heating element secured to said liner bottom wall relatively beneath said warmer drawer; a temperature sensor disposed within said heating chamber; and a control device operable to control energization of said heating element to maintain the temperature within said heating chamber between a predetermined minimum temperature and a predetermined maximum temperature corresponding to a range of desired food serving temperatures, wherein said control device comprises a user-adjustable infinite switch.
In a further aspect, the present invention provides a method for controlling an electrical warmer drawer heating element to maintain a temperature within a lower heating chamber, comprising steps of: providing a range for placement on a floor, providing a cabinet to said range, providing an oven wrapper disposed within said cabinet. and at least partially defining an oven chamber, providing the lower heating chamber relatively beneath said oven chamber, providing a fixed panel defining a lower extent of the heating chamber, providing the electrical heating element within said heating chamber, adjacent to the panel, providing the warmer drawer slidably mounted in the lower heating chamber, above the heating element and the panel, providing a temperature sensor disposed within said heating chamber and operable to sense temperature within said heating chamber, and providing controlling means for controlling said heating element such that a temperature within said heating chamber is maintained between a predetermined minimum temperature and a predetermined maximum temperature corresponding to a range of desired food serving temperatures; moving a heater control switch from an off position to a user-selected position, said user selected position corresponding to a duty cycle of heater element operation; energizing said heater element at full power;
sensing the temperature within said heating chamber using the temperature sensor; terminating full power energization of said heater element at said predetermined maximum temperature; energizing said heater element at said predetermined duty cycle.
BRIEF DESCRIPTION OF THE DRAWINGS
Features of the present invention will be apparent with reference to the following description and drawings, wherein:
FIG. 1 is a perspective view of a cooking range with a food warmer in a fully extended position;
FIG. 2 is a rear perspective view of a food warmer drawer according to the present invention;
FIG. 3 is a front elevational view of a lower portion of the cooking range shown in FIG. 1, with the food warmer drawer removed therefrom;
FIG. 4a, 4b and 4c, are respectively, a front elevational view, a top plan view, and a side elevational -3a-view of a front heat shield panel or grate according to the present invention;
FIG. 4d is a cross sectional view of the front heat shield as seen along line 4d-4d of FIG. 4a;
FIG. 5a, 5b and 5c are, respectively, a front elevational view, a top plan view, and a side elevational view of a rear heat shield panel according to the present invention;
-3b-1 FIG. 6a, Gb, and Gc are, respectively, a top plan 2 view, a front elevational view, and a side elevational view 3 of a lower heat shield panel according to the present 4 invention;
FIG. 7a, 7b, and 7c are, respectively, a bottom plan 6 view, a front elevational view, and a side elevational view 7 of ~n~upper heat shield panel according to the present 8 invention;
9 'FIGS. 8a, 8b, and 8c are, respectively, a front elevational view, a top plan view, and a side elevational 11 view of a temperature sensor mounting brac)cet according to 12 the present invention;
13 FIGS. 9a, 9b, and 9c are, respectively, a front 14 elevational view, a top plan view, and a side elevational view of a warmer drawer temperature sensor according to the 16 present invention;
17 FIG. 10 is a side elevational view of a warmer drawer 18 glide assembly according to the present invention;
19 FIG. 11 is an end elevational view of the warmer drawer glide assembly shown in FIG. 10.
21 FIG. 12 is top plan view of a heating element 22 according to the present invention;
23 FIG. 13 is a perspective view of a heating element 24 mounting clip according to the present invention;
FIG. 14 is a front elevational view of an oven chassis 26 wrapper according to the present invention; and, 27 FIG. 15 is a schematic diagram illustrating a control 28 circuit for the warmer drawer heating element.
It should be noted that in the detailed description 31 which follows, identical components have the same reference 32 numeral, regardless are shown in different of whether they 33 embodiments of the present invention.
It should also be 34 noted that, in order to clearly and concisely disclose the 1 present invention, the drawings may not necessarily be to 2 scale and certain features of the invention may be shown in 3 somewhat schematic form.
4 With reference to FIG. 1, a household range 20 incorporating the present invention is illustrated. The 6 range includes a cabinet to which an oven door 22 is 7 secured so as to permit pivotal movement of the door about 8 its bottom edge. The cabinet includes a top panel which 9 includes surface heating elements (not shown). A control panel 24 extends upwardly from adjacent a rear portion of 11 the top panel, and includes a plurality of control devices, 12 such as dials, switches, buttons, and/or knobs.
13 The control devices provided by the control panel 14 include a warmer drawer heater control switch 26, and associated indicator light 28. Preferably, the warmer 16 drawer heater control switch 26 is rotatably mounted to the 17 control panel, and is movable in a push-and-turn fashion to 18 any user-selected position between an off position, and a 19 high heat position. More preferably, the warmer drawer heater control switch 26 is an infinite switch wherein the 21 duty cycle (ratio of heater on-time to heater on-time plus 22 heater off-time) varies from zero, when the switch is set 23 to the off position, to one when the switch 26 is set to 24 the high position.
As will be described more fully hereafter, rotation of 26 the'w~rmer drawer heater control switch 26 between the 27 various user-selected positions varies the duty cycle of a 28 warmer drawer heating element 32. It is believed that 29 operation of infinite switches is well known to one skilled in the art and, therefore, will not be further discussed 31 hereinafter.
32 With reference to FIG. 2, the warmer drawer 34 33 according to the present invention is illustrated. The 34 warmer drawer preferably includes a pair of lateral side walls 36, a rear wall 38, a bottom wall 40, and a front 36 wall 42 which cooperate to define a receptacle adapted to 37 receive food stuffs to be maintained at an acceptable ' CA 02204795 1997-OS-08 1 above-ambient serving temperature.
2 The front wall 42 includes a front panel 44 from which 3 a handle extends (FIG. 1). Each of the lateral side walls 4 36 had a first portion 47 of a glide assembly 48 secured thereto, as will be described more fully hereafter.
6 The. front wall and panel 42, 44 extend or project 7 laterally and vertically outboard and perpendicular to the 8 lateral side walls 36 and bottom wall 40 of the drawer. An 9 annuhar heat seal member or gasket 50 is attached to a rearward facing surface of the front wall 42 and surrounds 11 the lateral side walls 36 and bottom wall 40, as 12 illustrated. When the drawer is in,a retracted or closed 13 position, the heat seal member 50 limits the escape of heat 14 from within the warmer drawer 34 and heating chamber 54, to be described hereafter. Preferably, the heat seal member 16 is formed from material commonly used to seal the periphery 17 of the oven door to the cabinet.
18 The heat seal member 50 does not prevent air from 19 being drawn through slotted openings 56 in the grate 52, as is desirable to supply supplementary combustion air to a 21 lower burner of a gas range. As will be apparent to one 22 skilled in the art, the front grate 52 may be modified and 23 the usable heating chamber height increased accordingly for 24 electric ranges, since supplementary combustion air is not required.
26 . The walls of the warmer drawer 34 are preferably 27 formed from steel, and have a porcelainized inner surface.
28 A porcelain inner surface of the warmer drawer is 29 preferable over a painted surface for a number of reasons.
These reasons include heat tolerance, resistance to 31 scratches and wear, ease of cleaning, and aesthetic 32 continuity with other surfaces of the oven. The warmer 33 drawer 34 may receive one or more racks (not shown) which 34 support foodstuffs in a spaced relationship to the bottom wall 40.
36 With reference to FIG. 3, the range cabinet provides 37 an open space between the bottom of the cooking oven (not 1 shown) and the floor. The open space is defined, in part, 2 by lateral sidewalls 60 of an oven chassis wrapper 58, 3 which is illustrated in FIG. 14. The oven chassis wrapper 4 58 is generally of an inverted U-shape, and defines the lateral and top walls of the cooking oven. A bottom oven 6 wall (not shown) and rear oven wall (not shown) are 7 mechanically attached, such as by welding, to the oven 8 chassis wrapper to define the cooking oven.
9 A base portion of the oven chassis wrapper lateral walls 60 defines the lateral extent of the open space. A
11 warmer drawer liner assembly is attached to the cabinet in 12 the open space and cooperates with the lateral walls 60 to 13 define the heating chamber which receives the warmer drawer 14 34.
The warmer drawer liner assembly includes, in addition 16 to the front panel or grate 52, an upper panel 62, a lower 17 panel 64, and a rear panel 66.
18 The front panel or grate 52 is secured to the upper 19 panel 62, as will be described more fully hereafter and, with reference to FIGS. 4a-4d, includes a front wall 68, a 21 bottom wall 70, and a pair of upper tabs 72. The front 22 wall 68 has the slotted openings 56 formed therein, as 23 discussed hereinbefore. The bottom wall 70 and the upper 24 tabs 72 extend rearwardly from the front wall 68.
Each of the upper tabs 72 includes an opening 74 26 through which a mounting screw is inserted to secure the 27 front panel 52 to a front chassis wall of the range 20 28 (FIG: 1). The lower wall 70 has a proximal portion 76 29 adjacent the front wall and a distal portion 78 spaced from the front wall. The proximal portion 76 includes a pair of 31 openings 80 underlying the upper tabs 72 through which 32 access to the tabs may be gained for insertion/removal of 33 the mounting screws.
34 The distal portion 78 has a series of short slots 82 formed therein which separates the distal portion of the 36 lower wall into an alternating series of first tabs 84 and 37 second tabs a6. The first tabs 84 are generally co-planar _7_ 1 with the proximal portion 76 of the bottom wall, while the 2 second tabs 86 are bent upwardly at an angle to the common 3 plane of the first tabs 84 and the proximal portion 76, as 4 illustrated.
. The second or angled tabs 86 have openings 88 formed 6 therein through which screws are inserted to secure the 7 upper panel 62 to the front panel or grate 52. As will be 8 described more fully hereafter with reference to assembly 9 of the front panel to the upper panel, the upper panel 62 is inserted relatively above the first tabs 84 and 11 relatively below the second tabs 86, and screws are 12 inserted through the openings in the second tabs 86 and 13 through the upper panel 62 to secure the upper panel 62 to 14 the front panel 52.
The upper panel 62 is secured to the front panel or 16 grate 52, as described hereinbefore, and to the lateral 17 walls 60 of the oven chassis wrapper 58. The upper panel 18 is located rearwardly relative to the front panel or grate, 19 and defines an upper extent of the heating chamber.
With reference to FIGS. 7a-7c, the upper panel 62 21 includes a generally planar plate 90 from which a rearward 22 flange 92 and a pair of lateral flanges 94 are downwardly 23 bent. The lateral flanges 94 include openings through 24 which screws are inserted to secure the upper panel to the lateral walls 60 of the oven chassis wrapper 58. The front 2G edge of the upper panel is slidably inserted between the 27 first and second tabs 84, 86 of the front panel, and 28 includes openings through which screws are inserted to 29 secure the upper panel 62 to the front panel 52, as discussed hereinbefore.
31 The lower panel 64 is secured to the rear panel 66 and 32 to lateral walls 60 of the oven chassis wrapper, and 33 defines a lower extent of the heating chamber 54. With 34 reference to FIGS. 6a-6c, the lower panel 64 includes a plate member 96 from which a rear flange 98 and a pair of 36 lateral flanges 100 extend.
37 The rear flange 98 is bent generally perpendicular to _g_ . CA 02204795 1997-OS-08 1 the plate member 96, and is secured to the rear panel 66 by 2 means of a screw. The lateral flanges 100 are generally Z-3 shaped in cross section, and define openings through which 4 screws extend to secure the lateral flanges to the lateral walls 60 of the oven chassis wrapper 58.
6 The plate member 96 also provides a pair of mounting 7 tabs 102 and a series of dimpled mounting openings 104.
8 The mounting tabs 102 are bent upwardly from the plate 9 member 96 and define pockets for receipt of a temperature ~0 sensing and circuit enabling/disabling assembly, 11 hereinafter referred to as the temperature sensing 12 assembly. The mounting tabs 102 slidably, yet resiliently, 13 receive the temperature sensing assembly thereunder, as 14 will be described hereafter. The dimpled mounting openings 104 are provided to facilitate securing heating element 16 mounting clips 106 (FIG. 13) to the lower panel 64, as will 17 be described hereafter.
18 The rear panel 66 is secured to the lower panel 64 and 19 to the lateral walls 60 of the oven chassis wrapper 58, and extends between rearward edges of the upper and lower 21 panels 62, 64, and between the lateral walls of the oven 22 chassis wrapper. The rear panel defines a rearward extent 23 of the heating chamber 54.
24 ~ With reference to FIGS. 5a-5c, the rear panel 66 includes a plate 108 from.which a lower flange 110 and a 26 pair of lateral flanges 112 extend. The lateral flanges 27 112 extend generally rearwardly of the plate 108, and 28 include openings to assist in mechanical securement of the 29 lateral flanges to the lateral walls 60 of the oven chassis wrapper. The lower flange 110 has a generally inverted-L
31 shape, and is adapted to extend out over, and in front of 32 the rear flange 98 of the lower panel 64. A vertical face 33 114 of the lower flange 110 includes an opening through 34 which a mounting screw extends to secure the lower flange 110 to the rear flange 98.
36 As such, the panels 52, 62, 64, 66 cooperate with 37 the oven chassis wrapper 58 to define the heating chamber;
_g_ 1 which is closed at its lateral sides, rear side, upper 2 side, and lower side, and open at the front. The warmer 3 drawer 34 is slidably inserted into the heating chamber 54, 4 and's~lidably removed from the heating chamber, by means of the glide assembly 48, to be described further hereafter.
6 It should be noted that the illustrated warmer drawer 7 liner assembly is intended for an electric range. On gas 8 ranges, the rear panel is not used, and the rearward extent 9 of the heating chamber is defined by a vertical wall which has control devices for the lower gas burner assembly 11 mounted thereto. The vertical wall and control devices are 12 conventional and, therefore, are not specifically 13 illustrated.
14 Each of the lateral walls 60 of the oven chassis wrapper have a second portion 46 of the drawer glide 16 assembly 48 secured thereto. The first and second portions 17 47, 46 of the glide assembly 48 cooperate with one another 18 to permit the drawer 34 to be slidably inserted into the 19 heating chamber, and slidably removed from the heating chamber. Also, the first and second glide portions 47, 46 21 may be disengaged from one another to permit the warmer 22 drawer 34 to be completely disconnected and removed from 23 the range 20, as would be desirable for cleaning and/or 24 maintenance purposes. It is understood that numerous glide assemblies are known in the art, and various other glide 26 assemblies may be substituted for the illustrated glide 27 assembly 48 without departing from the scope and spirit of 28 the present invention.
29 The heating element 32 (FIG. 12) and temperature sensing assembly (FIG. 3) are disposed within the heating 31 chamber 54 and secured to the lower panel 64. The heating 32 element 32 preferably comprises a tubular, electrical 33 resistance-type heating element which is fastened to the 34 lower panel 64 via the mounting clips 106 (FIG. 13) and a mounting bracket 118 (FIG. 8a-8c). The mounting clips 106 36 are attached to the mounting openings 104 in the lower 37 panel and clamp the heating element 32 to the lower panel 1 64. Naturally, more or less than the illustrated four 2 mounting clips 106 may be used to secure the heating 3 element 32 to the lower panel 64, if desired.
4 A mounting plate 116 of the heating element 32 is secured to the mounting bracket 118 of the temperature 6 sensing assembly, as will be described hereafter. The 7 heating element 32 is electrically connected to a 8 temperature sensor 30, and is powered in accordance with 9 the user-selected setting of the control switch 26 and as needed to maintain the temperature within the heating 11 chamber 54, as sensed by the temperature sensor 30, within 12 a predetermined desired range of operating temperatures, as 13 will be described hereinafter with reference to the control 14 circuit illustrated in FIG. 15.
The temperature sensing assembly includes the 16 temperature sensor 30 and the mounting bracket 118. The 17 temperature sensor 30 is secured to the mounting bracket 18 118 in an elevated position, as illustrated in FIG. 3, and 19 is operable to sense the temperature within the heating chamber 54.
21 . kith reference to FIGS. 8a-8c, the mounting bracket 22 118 includes a body member 120 from which a base flange 122 23 extends rearwardly. The base flange is slidably received 24 under the mounting tabs 102 and mechanically attached, preferably by a screw, to the lower panel G4. The body 26 member 120 defines an elongated opening 123 which receives 27 the temperature sensor 30, and includes a plurality of 28 openings through which fasteners extend to secure the 29 temperature sensor 30 and the heating element mounting plate 116 to the mounting bracket 118.
31 The temperature sensor 30 has a forwardly projecting 32 sensor portion 126, a mounting flange 128, and a rearwardly 33 extending connector portion 130. The mounting flange 128 34 includes a pair of lateral openings through which fasteners extend to secure the temperature sensor 30 to the mounting 36 bracket 118. The temperature sensor 30 is inserted through 37 the elongated opening 123 in the mounting bracket body, 1 such that the sensor portion 126 faces toward the warmer 2 drawer 34 and the open front of the heating chamber 54 and 3 the connector portion 130 faces toward the rear panel 66.
4 The connecting portion 130 is electrically connected, via suitable conductors, to the control switch 26 and the 6 heating element 32.
7 The location of the sensor 30 and mounting bracket 118 8 gives the control circuit its ambient compensation 9 characteristics. For example, and as will be apparent from the description to follow, relatively more heat may have to 11 be input into the heating chamber to reach the 12 predetermined maximum temperature during low ambient 13 conditions than during high ambient conditions. Putting 14 more heat into the heating chamber during low ambient may help reduce cycling as the time required to reach the 16 minimum temperature will be extended. Moreover, the 17 temperature within the warmer drawer corresponding to the 18 predetermined maximum heating chamber temperature may be 19 relatively higher during low ambient conditions than during ~ high ambient conditions. For high ambient conditions, less 21 heat may be required to reach the predetermined maximum 22 heating chamber temperature, and less heat is lost to 23 atmosphere, so temperature within the heating chamber and 24 the warmer drawer may be relatively more uniform and static.
26 The warmer drawer 341of the present invention is 27 located relatively above the heating element 32 and, 28 therefore, the present invention takes advantage of the 29 natural tendency of relatively hot air to rise. ~s such, the food stuffs contained within the drawer 34 are in a 31 relatively hot portion of the heating chamber 54. As 32 mentioned briefly hereinbefore, it may be desirable to 33 place one or more removable racks within the drawer 34 to 34 space the foods being warmed away from the bottom wall 40 of the drawer. Spacing of the food from the bottom wall 40 36 permits warm air to flow beneath the food and facilitates 37 more even heating thereof. Spacing of the food from the 1 bottom wall 40 also prevents localized over-heating of the 2 food at the interface with the bottom wall, since the 3 bottom wall will be relatively hot, as compared to air 4 within the heating chamber 54, due to the proximity of the bottom wall to the heating element 32.
6 With reference to FIG.~15, a control circuit 131 for 7 the warmer drawer heating element 32 is illustrated. The 8 circuit 131 generally includes an oven self-cleaning cycle 9 lock=out switch 132, the heater control switch 26, the ~0 warmer indicator light 28, the temperature sensor 30, the 11 warmer drawer heating element 32, and a diode 134. The 12 heater control switch 26 provides first and second pairs of 13 contacts 26a, 26b. The first pair of contacts 26a are 14 closed whenever the switch 26 is turned on. The second pair of contacts open and close when the switch 26 is 16 turned on, the frequency of opening and closing depending 17 upon the angular position of the switch 26 to vary or 18 adjust the duty cycle of heater operation. For example, 19 when the heater control switch 26 is turned to "high", the second pair of contacts 26b are mechanically locked in a 21 closed position whereas, when the switch 26 is turned to 22 the "low" position, the second pair of contacts 26b will be 23 closed only a portion of the time (e.g., 20%) and will be 24 open the rest of the time. It is considered that the above-described operation of the switch 2G is well known in 26 the infinite switch art.
27 The lock-out switch 132 opens and thereby de-activates 28 or renders inoperable the warmer drawer heating element 32, '29 and the heater control switch 26, when the oven is operated in a self-cleaning mode and, therefore, prevents 31 energization of the heating element 32 during a self-32 cleaning cycle.
33 The first pair of heater control switch contacts 26a 34 are connected in series with the lock-out switch 132. The warmer indicator light 28 is connected in parallel with the 36 warmer heating element 32 and a heating element 37 energization control circuit 136 and, therefore, is 1 illuminated whenever the heating element 32 is powered to 2 provide visual indication to the user that the warmer 3 heating element 32 is operating.
4 The temperature sensor 30 provides a thermally-actuated switch 30a which is normally-closed. The warmer 6 element energization circuit 136 includes the diode 134 and 7 the second pair of heater control switch contacts 2.6b in 8 parallel with the temperature sensor switch 30a, as 9 illustrated. Therefore, when the heater control switch 26 is turned from "off" to any position, the series 11 combination of the second pair of heater control switch 12 contacts 26b and the diode 134 is shorted by the parallel 13 branch due to the normally-closed temperature sensor switch 14 30a.
The heating element 32 is therefore in series with the 16 temperature sensor switch 30a, and full power is applied to 17 the heating element 32. At this point, no current flows 18 through branch of the energization circuit 136 containing 19 the diode 134 and the second pair of heater control switch contacts 36b. This period of operation is referred to 21 herein as the preheating cycle during which the heating 22 element 32 is operated at full power to more quickly bring 23 the warmer drawer 34 up to the maximum operating or peak 24 preheat temperature. When the temperature within the heating chamber 54 reaches the predetermined maximum 26 desired temperature or peak preheat temperature, the 27 temperature sensor switch 30a opens and control of the 28 heating element energization is given over to the heater 29 control switch 26. The time required to reach the predetermined maximum temperature depends upon a number of 31 factors, including the size, temperature, and type of food 32 being warmed,~and the ambient temperature.
33 The heating chamber temperature corresponds to the 34 warmer drawer temperature (i.e., food temperature), so that sensing of the heating chamber temperature is an accurate 36 guide to the warmer_ drawer temperature and, as will be 37 apparent from the following description, the sensed heating 1 chamber temperature is used to control energization of the 2 heating element 32 to maintain the warmer drawer 3 temperature within a range of desired food serving 4 temperatures.
Due to the diode 134, only half-wave rectified current 6 flows through the heating element 32 which, therefore, is 7 limited to half maximum power if the warmer switch is set 8 to "high". As noted hereinbefore, the duty cycle of the 9 heating element operation is controlled by the angular position of the heater control switch 2G which, in turn, 11 corresponds to the rate or frequency of opening/closing of 12 the second pair of heater control switch contacts 26b.
13 The duty cycle controls the amount of power dissipated 14 in the heater element 32 which, in turn, affects the amount of heat energy added to the warmer drawer heating chamber 16 54 and, hence, the warmer drawer 34. The rate at which the 17 heating chamber temperature falls (from the maximum 18 temperature at the end of the preheat cycle) is affected by 19 the food load within the warmer drawer, the ambient temperature, and the user-selected duty cycle of the warmer 21 drawer heating element 32 (i.e., the angular position of , 22 the switch 26).
23 For example, at a given ambient temperature, if a 24 relatively large, cool item of food is placed in the warmer drawer 34 and the warmer switch 2G is set to the "low"
26 position (which corresponds to a small duty cycle, e.g., 27 .20), the temperature within the heating chamber 54 and the 28 warmer drawer 34, following the preheat cycle, will fall 29 faster than if a similarly sized but hotter item of food is placed in the warmer drawer and the warmer switch 26 is set 31 to high (i.e., full one-half power, switch duty cycle 32 equals 1.0). Similarly, if a small, hot food item is 33 placed in the warmer drawer 34 in a low ambient environment 34 and the warmer switch 26 is set to "medium", the temperature within the heating chamber 54 and the warmer 36 drawer will fall faster than if an item of similar size and 37 temperature is placed in the warmer drawer in a high 1 ambient environment and the warmer switch is set to the 2 "medium" position.
3 If the heating chamber temperature drops below a 4 predetermined minimum desired temperature (which corresponds to a minimum desired serving temperature within 6 the warmer drawer), the temperature sensor contacts close, 7 shorting the branch of the energization circuit 136 8 containing the diode 134 and the second pair of heater 9 contrbl switch contacts 26b, and full power is again applied to the heating element 32 until the heating chamber 11 temperature exceeds the maximum desired temperature 12 (corresponding to the maximum desired serving temperature 13 within the warmer drawer), at which point the temperature 14 sensor contacts open and control is returned to the heater control switch 26 at the user-selected duty cycle.
18 The heat seal member 50 does not prevent air from 19 being drawn through slotted openings 56 in the grate 52, as is desirable to supply supplementary combustion air to a 21 lower burner of a gas range. As will be apparent to one 22 skilled in the art, the front grate 52 may be modified and 23 the usable heating chamber height increased accordingly for 24 electric ranges, since supplementary combustion air is not required.
26 . The walls of the warmer drawer 34 are preferably 27 formed from steel, and have a porcelainized inner surface.
28 A porcelain inner surface of the warmer drawer is 29 preferable over a painted surface for a number of reasons.
These reasons include heat tolerance, resistance to 31 scratches and wear, ease of cleaning, and aesthetic 32 continuity with other surfaces of the oven. The warmer 33 drawer 34 may receive one or more racks (not shown) which 34 support foodstuffs in a spaced relationship to the bottom wall 40.
36 With reference to FIG. 3, the range cabinet provides 37 an open space between the bottom of the cooking oven (not 1 shown) and the floor. The open space is defined, in part, 2 by lateral sidewalls 60 of an oven chassis wrapper 58, 3 which is illustrated in FIG. 14. The oven chassis wrapper 4 58 is generally of an inverted U-shape, and defines the lateral and top walls of the cooking oven. A bottom oven 6 wall (not shown) and rear oven wall (not shown) are 7 mechanically attached, such as by welding, to the oven 8 chassis wrapper to define the cooking oven.
9 A base portion of the oven chassis wrapper lateral walls 60 defines the lateral extent of the open space. A
11 warmer drawer liner assembly is attached to the cabinet in 12 the open space and cooperates with the lateral walls 60 to 13 define the heating chamber which receives the warmer drawer 14 34.
The warmer drawer liner assembly includes, in addition 16 to the front panel or grate 52, an upper panel 62, a lower 17 panel 64, and a rear panel 66.
18 The front panel or grate 52 is secured to the upper 19 panel 62, as will be described more fully hereafter and, with reference to FIGS. 4a-4d, includes a front wall 68, a 21 bottom wall 70, and a pair of upper tabs 72. The front 22 wall 68 has the slotted openings 56 formed therein, as 23 discussed hereinbefore. The bottom wall 70 and the upper 24 tabs 72 extend rearwardly from the front wall 68.
Each of the upper tabs 72 includes an opening 74 26 through which a mounting screw is inserted to secure the 27 front panel 52 to a front chassis wall of the range 20 28 (FIG: 1). The lower wall 70 has a proximal portion 76 29 adjacent the front wall and a distal portion 78 spaced from the front wall. The proximal portion 76 includes a pair of 31 openings 80 underlying the upper tabs 72 through which 32 access to the tabs may be gained for insertion/removal of 33 the mounting screws.
34 The distal portion 78 has a series of short slots 82 formed therein which separates the distal portion of the 36 lower wall into an alternating series of first tabs 84 and 37 second tabs a6. The first tabs 84 are generally co-planar _7_ 1 with the proximal portion 76 of the bottom wall, while the 2 second tabs 86 are bent upwardly at an angle to the common 3 plane of the first tabs 84 and the proximal portion 76, as 4 illustrated.
. The second or angled tabs 86 have openings 88 formed 6 therein through which screws are inserted to secure the 7 upper panel 62 to the front panel or grate 52. As will be 8 described more fully hereafter with reference to assembly 9 of the front panel to the upper panel, the upper panel 62 is inserted relatively above the first tabs 84 and 11 relatively below the second tabs 86, and screws are 12 inserted through the openings in the second tabs 86 and 13 through the upper panel 62 to secure the upper panel 62 to 14 the front panel 52.
The upper panel 62 is secured to the front panel or 16 grate 52, as described hereinbefore, and to the lateral 17 walls 60 of the oven chassis wrapper 58. The upper panel 18 is located rearwardly relative to the front panel or grate, 19 and defines an upper extent of the heating chamber.
With reference to FIGS. 7a-7c, the upper panel 62 21 includes a generally planar plate 90 from which a rearward 22 flange 92 and a pair of lateral flanges 94 are downwardly 23 bent. The lateral flanges 94 include openings through 24 which screws are inserted to secure the upper panel to the lateral walls 60 of the oven chassis wrapper 58. The front 2G edge of the upper panel is slidably inserted between the 27 first and second tabs 84, 86 of the front panel, and 28 includes openings through which screws are inserted to 29 secure the upper panel 62 to the front panel 52, as discussed hereinbefore.
31 The lower panel 64 is secured to the rear panel 66 and 32 to lateral walls 60 of the oven chassis wrapper, and 33 defines a lower extent of the heating chamber 54. With 34 reference to FIGS. 6a-6c, the lower panel 64 includes a plate member 96 from which a rear flange 98 and a pair of 36 lateral flanges 100 extend.
37 The rear flange 98 is bent generally perpendicular to _g_ . CA 02204795 1997-OS-08 1 the plate member 96, and is secured to the rear panel 66 by 2 means of a screw. The lateral flanges 100 are generally Z-3 shaped in cross section, and define openings through which 4 screws extend to secure the lateral flanges to the lateral walls 60 of the oven chassis wrapper 58.
6 The plate member 96 also provides a pair of mounting 7 tabs 102 and a series of dimpled mounting openings 104.
8 The mounting tabs 102 are bent upwardly from the plate 9 member 96 and define pockets for receipt of a temperature ~0 sensing and circuit enabling/disabling assembly, 11 hereinafter referred to as the temperature sensing 12 assembly. The mounting tabs 102 slidably, yet resiliently, 13 receive the temperature sensing assembly thereunder, as 14 will be described hereafter. The dimpled mounting openings 104 are provided to facilitate securing heating element 16 mounting clips 106 (FIG. 13) to the lower panel 64, as will 17 be described hereafter.
18 The rear panel 66 is secured to the lower panel 64 and 19 to the lateral walls 60 of the oven chassis wrapper 58, and extends between rearward edges of the upper and lower 21 panels 62, 64, and between the lateral walls of the oven 22 chassis wrapper. The rear panel defines a rearward extent 23 of the heating chamber 54.
24 ~ With reference to FIGS. 5a-5c, the rear panel 66 includes a plate 108 from.which a lower flange 110 and a 26 pair of lateral flanges 112 extend. The lateral flanges 27 112 extend generally rearwardly of the plate 108, and 28 include openings to assist in mechanical securement of the 29 lateral flanges to the lateral walls 60 of the oven chassis wrapper. The lower flange 110 has a generally inverted-L
31 shape, and is adapted to extend out over, and in front of 32 the rear flange 98 of the lower panel 64. A vertical face 33 114 of the lower flange 110 includes an opening through 34 which a mounting screw extends to secure the lower flange 110 to the rear flange 98.
36 As such, the panels 52, 62, 64, 66 cooperate with 37 the oven chassis wrapper 58 to define the heating chamber;
_g_ 1 which is closed at its lateral sides, rear side, upper 2 side, and lower side, and open at the front. The warmer 3 drawer 34 is slidably inserted into the heating chamber 54, 4 and's~lidably removed from the heating chamber, by means of the glide assembly 48, to be described further hereafter.
6 It should be noted that the illustrated warmer drawer 7 liner assembly is intended for an electric range. On gas 8 ranges, the rear panel is not used, and the rearward extent 9 of the heating chamber is defined by a vertical wall which has control devices for the lower gas burner assembly 11 mounted thereto. The vertical wall and control devices are 12 conventional and, therefore, are not specifically 13 illustrated.
14 Each of the lateral walls 60 of the oven chassis wrapper have a second portion 46 of the drawer glide 16 assembly 48 secured thereto. The first and second portions 17 47, 46 of the glide assembly 48 cooperate with one another 18 to permit the drawer 34 to be slidably inserted into the 19 heating chamber, and slidably removed from the heating chamber. Also, the first and second glide portions 47, 46 21 may be disengaged from one another to permit the warmer 22 drawer 34 to be completely disconnected and removed from 23 the range 20, as would be desirable for cleaning and/or 24 maintenance purposes. It is understood that numerous glide assemblies are known in the art, and various other glide 26 assemblies may be substituted for the illustrated glide 27 assembly 48 without departing from the scope and spirit of 28 the present invention.
29 The heating element 32 (FIG. 12) and temperature sensing assembly (FIG. 3) are disposed within the heating 31 chamber 54 and secured to the lower panel 64. The heating 32 element 32 preferably comprises a tubular, electrical 33 resistance-type heating element which is fastened to the 34 lower panel 64 via the mounting clips 106 (FIG. 13) and a mounting bracket 118 (FIG. 8a-8c). The mounting clips 106 36 are attached to the mounting openings 104 in the lower 37 panel and clamp the heating element 32 to the lower panel 1 64. Naturally, more or less than the illustrated four 2 mounting clips 106 may be used to secure the heating 3 element 32 to the lower panel 64, if desired.
4 A mounting plate 116 of the heating element 32 is secured to the mounting bracket 118 of the temperature 6 sensing assembly, as will be described hereafter. The 7 heating element 32 is electrically connected to a 8 temperature sensor 30, and is powered in accordance with 9 the user-selected setting of the control switch 26 and as needed to maintain the temperature within the heating 11 chamber 54, as sensed by the temperature sensor 30, within 12 a predetermined desired range of operating temperatures, as 13 will be described hereinafter with reference to the control 14 circuit illustrated in FIG. 15.
The temperature sensing assembly includes the 16 temperature sensor 30 and the mounting bracket 118. The 17 temperature sensor 30 is secured to the mounting bracket 18 118 in an elevated position, as illustrated in FIG. 3, and 19 is operable to sense the temperature within the heating chamber 54.
21 . kith reference to FIGS. 8a-8c, the mounting bracket 22 118 includes a body member 120 from which a base flange 122 23 extends rearwardly. The base flange is slidably received 24 under the mounting tabs 102 and mechanically attached, preferably by a screw, to the lower panel G4. The body 26 member 120 defines an elongated opening 123 which receives 27 the temperature sensor 30, and includes a plurality of 28 openings through which fasteners extend to secure the 29 temperature sensor 30 and the heating element mounting plate 116 to the mounting bracket 118.
31 The temperature sensor 30 has a forwardly projecting 32 sensor portion 126, a mounting flange 128, and a rearwardly 33 extending connector portion 130. The mounting flange 128 34 includes a pair of lateral openings through which fasteners extend to secure the temperature sensor 30 to the mounting 36 bracket 118. The temperature sensor 30 is inserted through 37 the elongated opening 123 in the mounting bracket body, 1 such that the sensor portion 126 faces toward the warmer 2 drawer 34 and the open front of the heating chamber 54 and 3 the connector portion 130 faces toward the rear panel 66.
4 The connecting portion 130 is electrically connected, via suitable conductors, to the control switch 26 and the 6 heating element 32.
7 The location of the sensor 30 and mounting bracket 118 8 gives the control circuit its ambient compensation 9 characteristics. For example, and as will be apparent from the description to follow, relatively more heat may have to 11 be input into the heating chamber to reach the 12 predetermined maximum temperature during low ambient 13 conditions than during high ambient conditions. Putting 14 more heat into the heating chamber during low ambient may help reduce cycling as the time required to reach the 16 minimum temperature will be extended. Moreover, the 17 temperature within the warmer drawer corresponding to the 18 predetermined maximum heating chamber temperature may be 19 relatively higher during low ambient conditions than during ~ high ambient conditions. For high ambient conditions, less 21 heat may be required to reach the predetermined maximum 22 heating chamber temperature, and less heat is lost to 23 atmosphere, so temperature within the heating chamber and 24 the warmer drawer may be relatively more uniform and static.
26 The warmer drawer 341of the present invention is 27 located relatively above the heating element 32 and, 28 therefore, the present invention takes advantage of the 29 natural tendency of relatively hot air to rise. ~s such, the food stuffs contained within the drawer 34 are in a 31 relatively hot portion of the heating chamber 54. As 32 mentioned briefly hereinbefore, it may be desirable to 33 place one or more removable racks within the drawer 34 to 34 space the foods being warmed away from the bottom wall 40 of the drawer. Spacing of the food from the bottom wall 40 36 permits warm air to flow beneath the food and facilitates 37 more even heating thereof. Spacing of the food from the 1 bottom wall 40 also prevents localized over-heating of the 2 food at the interface with the bottom wall, since the 3 bottom wall will be relatively hot, as compared to air 4 within the heating chamber 54, due to the proximity of the bottom wall to the heating element 32.
6 With reference to FIG.~15, a control circuit 131 for 7 the warmer drawer heating element 32 is illustrated. The 8 circuit 131 generally includes an oven self-cleaning cycle 9 lock=out switch 132, the heater control switch 26, the ~0 warmer indicator light 28, the temperature sensor 30, the 11 warmer drawer heating element 32, and a diode 134. The 12 heater control switch 26 provides first and second pairs of 13 contacts 26a, 26b. The first pair of contacts 26a are 14 closed whenever the switch 26 is turned on. The second pair of contacts open and close when the switch 26 is 16 turned on, the frequency of opening and closing depending 17 upon the angular position of the switch 26 to vary or 18 adjust the duty cycle of heater operation. For example, 19 when the heater control switch 26 is turned to "high", the second pair of contacts 26b are mechanically locked in a 21 closed position whereas, when the switch 26 is turned to 22 the "low" position, the second pair of contacts 26b will be 23 closed only a portion of the time (e.g., 20%) and will be 24 open the rest of the time. It is considered that the above-described operation of the switch 2G is well known in 26 the infinite switch art.
27 The lock-out switch 132 opens and thereby de-activates 28 or renders inoperable the warmer drawer heating element 32, '29 and the heater control switch 26, when the oven is operated in a self-cleaning mode and, therefore, prevents 31 energization of the heating element 32 during a self-32 cleaning cycle.
33 The first pair of heater control switch contacts 26a 34 are connected in series with the lock-out switch 132. The warmer indicator light 28 is connected in parallel with the 36 warmer heating element 32 and a heating element 37 energization control circuit 136 and, therefore, is 1 illuminated whenever the heating element 32 is powered to 2 provide visual indication to the user that the warmer 3 heating element 32 is operating.
4 The temperature sensor 30 provides a thermally-actuated switch 30a which is normally-closed. The warmer 6 element energization circuit 136 includes the diode 134 and 7 the second pair of heater control switch contacts 2.6b in 8 parallel with the temperature sensor switch 30a, as 9 illustrated. Therefore, when the heater control switch 26 is turned from "off" to any position, the series 11 combination of the second pair of heater control switch 12 contacts 26b and the diode 134 is shorted by the parallel 13 branch due to the normally-closed temperature sensor switch 14 30a.
The heating element 32 is therefore in series with the 16 temperature sensor switch 30a, and full power is applied to 17 the heating element 32. At this point, no current flows 18 through branch of the energization circuit 136 containing 19 the diode 134 and the second pair of heater control switch contacts 36b. This period of operation is referred to 21 herein as the preheating cycle during which the heating 22 element 32 is operated at full power to more quickly bring 23 the warmer drawer 34 up to the maximum operating or peak 24 preheat temperature. When the temperature within the heating chamber 54 reaches the predetermined maximum 26 desired temperature or peak preheat temperature, the 27 temperature sensor switch 30a opens and control of the 28 heating element energization is given over to the heater 29 control switch 26. The time required to reach the predetermined maximum temperature depends upon a number of 31 factors, including the size, temperature, and type of food 32 being warmed,~and the ambient temperature.
33 The heating chamber temperature corresponds to the 34 warmer drawer temperature (i.e., food temperature), so that sensing of the heating chamber temperature is an accurate 36 guide to the warmer_ drawer temperature and, as will be 37 apparent from the following description, the sensed heating 1 chamber temperature is used to control energization of the 2 heating element 32 to maintain the warmer drawer 3 temperature within a range of desired food serving 4 temperatures.
Due to the diode 134, only half-wave rectified current 6 flows through the heating element 32 which, therefore, is 7 limited to half maximum power if the warmer switch is set 8 to "high". As noted hereinbefore, the duty cycle of the 9 heating element operation is controlled by the angular position of the heater control switch 2G which, in turn, 11 corresponds to the rate or frequency of opening/closing of 12 the second pair of heater control switch contacts 26b.
13 The duty cycle controls the amount of power dissipated 14 in the heater element 32 which, in turn, affects the amount of heat energy added to the warmer drawer heating chamber 16 54 and, hence, the warmer drawer 34. The rate at which the 17 heating chamber temperature falls (from the maximum 18 temperature at the end of the preheat cycle) is affected by 19 the food load within the warmer drawer, the ambient temperature, and the user-selected duty cycle of the warmer 21 drawer heating element 32 (i.e., the angular position of , 22 the switch 26).
23 For example, at a given ambient temperature, if a 24 relatively large, cool item of food is placed in the warmer drawer 34 and the warmer switch 2G is set to the "low"
26 position (which corresponds to a small duty cycle, e.g., 27 .20), the temperature within the heating chamber 54 and the 28 warmer drawer 34, following the preheat cycle, will fall 29 faster than if a similarly sized but hotter item of food is placed in the warmer drawer and the warmer switch 26 is set 31 to high (i.e., full one-half power, switch duty cycle 32 equals 1.0). Similarly, if a small, hot food item is 33 placed in the warmer drawer 34 in a low ambient environment 34 and the warmer switch 26 is set to "medium", the temperature within the heating chamber 54 and the warmer 36 drawer will fall faster than if an item of similar size and 37 temperature is placed in the warmer drawer in a high 1 ambient environment and the warmer switch is set to the 2 "medium" position.
3 If the heating chamber temperature drops below a 4 predetermined minimum desired temperature (which corresponds to a minimum desired serving temperature within 6 the warmer drawer), the temperature sensor contacts close, 7 shorting the branch of the energization circuit 136 8 containing the diode 134 and the second pair of heater 9 contrbl switch contacts 26b, and full power is again applied to the heating element 32 until the heating chamber 11 temperature exceeds the maximum desired temperature 12 (corresponding to the maximum desired serving temperature 13 within the warmer drawer), at which point the temperature 14 sensor contacts open and control is returned to the heater control switch 26 at the user-selected duty cycle.
16 Accordingly, the warmer drawer temperature is maintained 17 between maximum and minimum desired serving temperatures.
18 As should be apparent from the foregoing, control over 19 energization of the heating element 32 alternates between full power when the temperature sensor contacts close 21 (preheat cycle and low heating chamber/warmer drawer 22 temperature) and the user-selected duty cycle. As noted 23 hereinbefore, the heat input into the heating chamber to 24 reach the maximum desired heating chamber temperature will vary depending at least upon ambient temperature.
26 Similarly, the rate at which the heating chamber 27 temperature falls to the predetermined minimum desired 28 heating chamber temperature will vary depending at least 29 upon ambient temperature, food size and type, and user selected setting of the control switch 26.
31 It is also noted that the maximum and minimum warmer 32 drawer temperatures may vary in dependence upon ambient 33 temperature. For example, the maximum warmer drawer 34 temperature may be relatively higher in low ambient conditions than in high ambient conditions. Similarly, the 36 minimum warmer drawer temperature may be relatively higher 37 in low ambient conditions than in high ambient conditions.
1 Since relatively more heat is lost to the environment in 2 low ambient conditions than in high ambient conditions, the 3 noted temperature compensation feature reduces cycling of 4 the heater element between the user-selected duty cycle and full power cycle than would otherwise occur. The maximum 6 and minimum warmer drawer temperatures fall within a range 7 of desired food serving temperatures.
g While the preferred embodiment of the present 9 invention is shown and described herein, it is to be understood that the same is not so limited but shall cover 11 and include any and all modifications thereof which fall 12 within the purview of the invention.
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26 Similarly, the rate at which the heating chamber 27 temperature falls to the predetermined minimum desired 28 heating chamber temperature will vary depending at least 29 upon ambient temperature, food size and type, and user selected setting of the control switch 26.
31 It is also noted that the maximum and minimum warmer 32 drawer temperatures may vary in dependence upon ambient 33 temperature. For example, the maximum warmer drawer 34 temperature may be relatively higher in low ambient conditions than in high ambient conditions. Similarly, the 36 minimum warmer drawer temperature may be relatively higher 37 in low ambient conditions than in high ambient conditions.
1 Since relatively more heat is lost to the environment in 2 low ambient conditions than in high ambient conditions, the 3 noted temperature compensation feature reduces cycling of 4 the heater element between the user-selected duty cycle and full power cycle than would otherwise occur. The maximum 6 and minimum warmer drawer temperatures fall within a range 7 of desired food serving temperatures.
g While the preferred embodiment of the present 9 invention is shown and described herein, it is to be understood that the same is not so limited but shall cover 11 and include any and all modifications thereof which fall 12 within the purview of the invention.
_17_
Claims (12)
1. A cooking appliance, comprising a cabinet, a lower heating chamber adapted to receive a food receiving member, a heating element disposed within said heating chamber, means for controlling said heating element such that a temperature within said heating chamber is maintained between a predetermined minimum temperature and a predetermined maximum temperature corresponding to a range of desired food serving temperature, wherein said controlling means comprise a temperature sensor and an infinite switch.
2. A cooking appliance according to claim 1, wherein said temperature sensor is disposed within said heating chamber and is operable to sense temperature within said heating chamber.
3. A cooking appliance according to claim 1, wherein said infinite switch controls a duty cycle of said heating element.
4. A cooking appliance according to claim 2, wherein said temperature sensor is operable to energize said heating element at full power during a preheating cycle until said predetermined maximum heating chamber temperature is reached.
5. A cooking appliance according to claim 4, wherein, following said preheating cycle, said heating element is energised in accordance with a user-selected duty cycle.
6. A method for controlling a warmer drawer heating element to maintain a temperature within a heating chamber between a predetermined maximum and a predetermined minimum, said warmer drawer heating element being disposed within said heating chamber, comprising the steps of:
moving a heater control switch from an off position to a user-selected position, said user selected position corresponding to a duty cycle of heater element operation;
energizing said heater element at full power;
sensing the temperature within said heating chamber;
terminating full power energization of said heater element at said predetermined maximum temperature;
energizing said heater element at said predetermined duty cycle;
terminating energization of said heater element at said predetermined duty cycle at said predetermined minimum temperature;
energizing said heater element at full power; and terminating full power energization of said heater element at said predetermined maximum temperature;
resuming energization of said heater element at said predetermined duty cycle.
moving a heater control switch from an off position to a user-selected position, said user selected position corresponding to a duty cycle of heater element operation;
energizing said heater element at full power;
sensing the temperature within said heating chamber;
terminating full power energization of said heater element at said predetermined maximum temperature;
energizing said heater element at said predetermined duty cycle;
terminating energization of said heater element at said predetermined duty cycle at said predetermined minimum temperature;
energizing said heater element at full power; and terminating full power energization of said heater element at said predetermined maximum temperature;
resuming energization of said heater element at said predetermined duty cycle.
7. A cooking appliance, comprising:
a cabinet;
an oven wrapper disposed within said cabinet, said oven wrapper having a generally inverted u-shape including a pair of lateral side walls;
a warmer liner, comprising:
a liner top wall disposed generally between said lateral side walls;
a liner bottom wall disposed generally between said lateral side walls, wherein said liner top wall and bottom wall cooperate with said lateral side walls to define a heating chamber;
a warmer drawer adapted to be received within said heating chamber;
a heating element secured to said liner bottom wall relatively beneath said warmer drawer;
a temperature sensor disposed within said heating chamber; and a control device operable to control energization of said heating element to maintain the temperature within said heating chamber between a predetermined minimum temperature and a predetermined maximum temperature corresponding to a range of desired food serving temperatures, wherein said control device comprises a user-adjustable infinite switch.
a cabinet;
an oven wrapper disposed within said cabinet, said oven wrapper having a generally inverted u-shape including a pair of lateral side walls;
a warmer liner, comprising:
a liner top wall disposed generally between said lateral side walls;
a liner bottom wall disposed generally between said lateral side walls, wherein said liner top wall and bottom wall cooperate with said lateral side walls to define a heating chamber;
a warmer drawer adapted to be received within said heating chamber;
a heating element secured to said liner bottom wall relatively beneath said warmer drawer;
a temperature sensor disposed within said heating chamber; and a control device operable to control energization of said heating element to maintain the temperature within said heating chamber between a predetermined minimum temperature and a predetermined maximum temperature corresponding to a range of desired food serving temperatures, wherein said control device comprises a user-adjustable infinite switch.
8. A method for controlling an electrical warmer drawer heating element to maintain a temperature within a lower heating chamber, comprising steps of:
providing a range for placement on a floor, providing a cabinet to said range, providing an oven wrapper disposed within said cabinet and at least partially defining an oven chamber, providing the lower heating chamber relatively beneath said oven chamber, providing a fixed panel defining a lower extent of the heating chamber, providing the electrical heating element within said heating chamber, adjacent to the panel, providing the warmer drawer slidably mounted in the lower heating chamber, above the heating element and the panel, providing a temperature sensor disposed within said heating chamber and operable to sense temperature within said heating chamber, and providing controlling means for controlling said heating element such that a temperature within said heating chamber is maintained between a predetermined minimum temperature and a predetermined maximum temperature corresponding to a range of desired food serving temperatures;
moving a heater control switch from an off position to a user-selected position, said user selected position corresponding to a duty cycle of heater element operation;
energizing said heater element at full power;
sensing the temperature within said heating chamber using the temperature sensor;
terminating full power energization of said heater element at said predetermined maximum temperature;
energizing said heater element at said predetermined duty cycle.
providing a range for placement on a floor, providing a cabinet to said range, providing an oven wrapper disposed within said cabinet and at least partially defining an oven chamber, providing the lower heating chamber relatively beneath said oven chamber, providing a fixed panel defining a lower extent of the heating chamber, providing the electrical heating element within said heating chamber, adjacent to the panel, providing the warmer drawer slidably mounted in the lower heating chamber, above the heating element and the panel, providing a temperature sensor disposed within said heating chamber and operable to sense temperature within said heating chamber, and providing controlling means for controlling said heating element such that a temperature within said heating chamber is maintained between a predetermined minimum temperature and a predetermined maximum temperature corresponding to a range of desired food serving temperatures;
moving a heater control switch from an off position to a user-selected position, said user selected position corresponding to a duty cycle of heater element operation;
energizing said heater element at full power;
sensing the temperature within said heating chamber using the temperature sensor;
terminating full power energization of said heater element at said predetermined maximum temperature;
energizing said heater element at said predetermined duty cycle.
9. A method for controlling a warmer drawer heating element according to claim 8, comprising the further steps of:
terminating energization of said heater element at said predetermined duty cycle at said predetermined minimum temperature;
energizing said heater element at full power;
terminating full power energization of said heater element at said predetermined maximum temperature; and resuming energization of said heater element at said predetermined duty cycle.
terminating energization of said heater element at said predetermined duty cycle at said predetermined minimum temperature;
energizing said heater element at full power;
terminating full power energization of said heater element at said predetermined maximum temperature; and resuming energization of said heater element at said predetermined duty cycle.
10. A method for controlling a warmer drawer heating element according to claim 8, wherein said controlling means comprise the temperature sensor and an infinite switch.
11. A method for controlling a warmer drawer heating element according to claim 10, wherein, during a preheating cycle, said temperature sensor provides full power to said heating element to bring the temperature of said heating chamber to said maximum temperature.
12. A method for controlling a warmer drawer heating element according to claim 11, wherein, following said preheating cycle, power to said heating element is supplied in accordance with a user-selected duty cycle via said infinite switch.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/769,105 | 1996-12-18 | ||
| US08/769,105 US6191391B1 (en) | 1996-01-25 | 1996-12-18 | Warmer drawer for a cooking range |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2204795A1 CA2204795A1 (en) | 1998-06-18 |
| CA2204795C true CA2204795C (en) | 2006-07-18 |
Family
ID=25084473
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002204795A Expired - Lifetime CA2204795C (en) | 1996-12-18 | 1997-05-08 | Warmer drawer for a cooking range |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2204795C (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6166353A (en) * | 1997-08-22 | 2000-12-26 | White Consolidated Industries, Inc. | Free-standing warmer drawer |
-
1997
- 1997-05-08 CA CA002204795A patent/CA2204795C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| CA2204795A1 (en) | 1998-06-18 |
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| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKEX | Expiry |
Effective date: 20170510 |