US 3749081 A
Description (OCR text may contain errors)
United States Patent [1 1 Wilson 51 July 31, 1973 WINDOWED OVEN DOOR WITH ROTATABLE INNER PANEL 3/1967 Baughman 126/200 Primary Examiner-Carroll B. Dority, Jr. Assistant ExaminerLarry l. Schwartz AttorneyRichard L. Caslin et a].
571 ABSTRACT A windowed oven door design for a high-temperature self-cleaning oven. The door has a window of multipanes of transparent glass. There is an insulated inner door panel that is supported from the door for rotation on a central pivot. This inner panel also has a window opening with a glass pane. During normal cooking operations, the window of the inner panel is aligned with the window of the door for viewing within the oven cavity. in preparation for the self-cleaning cycle, the inner panel is first reversed so that it blocks the window opening of the door. Convection air currents pass through the door for cooling purposes during the cleaning cycle.
11 Claims, 5 Drawing Figures PATENTED JUL 31 ms SHEET 2 BF 2 BACKGROUND OF THE INVENTION A pyrolytic self-cleaning oven operates at oven temperatures as high as 950F. as is described in the basic patent of Bohdan Hurko, US. Pat. No. 3,121,158, which is assigned to the same assignee as is the present invention. Windows have been available in conventional oven doors for many years. Range users have become accustomed to the convenience of being able to observe the food while it is being cooked so as to avoid the necessity of opening the oven door and losing some of the oven heat in order to judge the degree of doneness of the food. Special window designs are necessary for oven doors of pyrolytic self-cleaning ovens such as the use of a movable radiation blocking shield which is positioned to cover the window during the self-cleaning cycle as is taught in th patent of Howard Baughman and Kermit Keeling, Sr., US Pat. No. 3,31 1,106. The main advantages of such a radiation blocking shield are that it reduces the heat loss through the window passage and thereby lowers the external surface temperatures of the door, as well as maintains a high temperature on the internal surface of the innermost glass pane during the self-cleaning cycle so as to insure the complete removal of all food soil from the inner pane by the pyrolytic process. Safety regulations of Underwriter Laboratories are becoming more strict regarding the allowable surface temperatures on the outer surface of the oven door during the self-cleaning operation.
A principal object of the present invention is to provide a windowed door for a high-temperature compartment with a reliable radiation blocking means of a substantial nature that does not detract from the appearance of the door.
A further object of the present invention is to provide a windowed oven door with a rotatable inner panel that is likewise provided with a window opening so that in one position the window openings are aligned for permitting the viewing within the oven cavity, and in another position the window opening in the door is blocked by the inner panel.
A further object of the present invention is to provide a windowed oven door of the class described with convection air channels for reducing the external temperatures of the door and damper means for blocking the convection air channels during normal cooking operations so as to prevent the glass panes from becoming soiled by grease entrained in the kitchen atmosphere and/or by the spillage of liquids or the like into the air vents in the top edge of the door.
SUMMARY OF THE INVENTION The present invention, in accordance with one form thereof, relates to an insulated door construction for use with a high-temperature oven where the door has an outer door panel and an inner door liner and an insulation guard disposed between the outer panel and inner liner with a layer of insulation between the insulation guard and the inner liner, as well as convection air channels in front of the insulation guard. The door includes a window openingjformed with multipanes of transparent glass. There is an insulated inner panel fastened to the inner door liner by a central shaft that is pivotally mounted Within the door. This inner panel also includes a window opening having at least one transparent glass pane that is adapted .to overlie the window opening in the door during normal cooking operations. To prepare for the high-temperature operation, the inner panel is rotated so as to block the window opening in the door and thereby reduce the heat loss through the door.
BRIEF DESCRIPTION OF THE DRAWINGS This invention will be better understood from the following description taken in conjunction with the accompanying drawings and its scope will be pointed out in the appended claims.
FIG. 1 is a perspective view of a free-standing domestic range having a windowed oven door embodying the present invention, where the door is shown in its horizontal, fully open position.
FIG. 2 is a cross sectional elevational view on an enlarged scale through the center of the door to show the general nature of the door construction as it would be arranged for normal cooking operations.
FIG. 3 is a fragmentary elevational view in the vicinity of the window opening of the door taken on the line 3-3 of FIG. 2 with the outer door panel removed so as to view the nature of the two dampers and the associated crank and linkages that are connected to the support shaft of the inner door panel for operation thereby.
FIG. 4 is a second modification of a windowed oven door of the present invention shown resting in its horizontal, fully open position, the main difference being the addition of an internal reflective shield connected to the support shaft of the inner panel wherein the shield is shown in a hidden position when the window opening is unobstructed for viewing within the oven cavity.
FIG. 5 is a front view of the oven door with the outer door panel removed taken on the line 5-5 of FIG. 4 (but turned on its side), showing the nature of the internal reflective shield and the single damper means that is arranged above the window opening in the door.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning now to a consideration of the drawings and in particular to FIG. 1, there is shown for illustrative purposes a free-standing electric range 10 having a top cooking surface 11 with a plurality of surface heating elements 12, a baking oven 13 formed by a box-like oven liner l4 and a front-opening access door 16. Of course, this invention is not limited for use in electric free-standing ranges. The oven could be heated by gas, it could be a built-in wall oven or any other type of high-temperature heated cavity. The oven cavity 13 is supplied with two standard heating elements; namely, a lower baking element 18 and an upper broiling element 19 located adjacent the top wall of the oven liner. The back edge of the cooking surface 11 is supplied with a backsplash 21 which supports a control panel including multiple selector switches 22 for the surface heating units 12 and an oven selector switch 24 and an oven thermostat control 26 and finally an oven timer 28 for timing both the cooking operations as well as the oven cleaning cycle. Positioned beneath the oven 13 is a pull-out drawer 30 which is a storage drawer for cooking utensils and the like. However, in a gas oven, this lower space is usually alotted to a broiler compartment.
The oven door 16 is hinged to the range body along the bottom edge of the door by means of hinge levers 32 of the nature as is shown in the patent of G. R. Sherman, U.S. Pat. No. 2,873,737, which is assigned to the same assignee as is the present invention. An oven door latch handle is shown at the front edge of the cooktop 11 for manipulation of a latch located beneath the cooktop for engaging an oven door in a closed position and locking it shut during the oven cleaning cycle. A typical oven latch design is shown in the patent of J. S. Fox, U.S. Pat. No. 3,367,697.
As is best seen in FIG. 2, the oven door 16 is ofgenerally sheet metal construction having three main elements; a decorative outer door panel 34, an inner door liner 36 and an insulated inner panel 38 that is supported from the inner door liner 36 by a rotatable stub shaft 40. The outer door panel 34 is of shallow pan shape by virtue of the fact that it has a slight rearwardly turned peripheral flange 41. The inner door liner 36 is also of shallow pan shape, and it is of mating construction into the outer door panel 34 by virtue of the fact that it has a front-turned peripheral flange 43. Suitable screw fasteners (not shown) attach the inner door liner 36 to the outer door panel 34 at the top of the door, while at the bottom of the door there is a tab and slot connecting relationship at 45 along most of the bottom edge of the door which prevents separation of the outer door panel from the inner door liner unless the screw fasteners at the top of the door are first removed. The inner door liner 36 includes a generally rectangular, central, outward embossment 47 of such a size as to fit closely within a recess 46 in the front frame 48 of the oven, as is best seen in FIG. 2. A sheet metal insulation guard 50 is assembled within the door and fastened to the inner surface of the inner door liner 36 to span the rectangular embossment 47. This embossment 47 is adapted to receive a layer of thermal insulating material 52, such as fibre glass or the like.
The door construction includes an upper window opening 54 which is provided with multi-panes of transparent glass, shown as elements 55, 56 and 57. The outermost pane 55 is shown fastened across the window opening in the outer door panel. The remaining two panes 56 and 57 are assembled together in a sealed subassembly or window pack 58 which includes a continuous central spacer frame 59 that is sandwiched between the two panes 56 and 57 and held in place by a continuous outer frame 61 to form a dead-air space 63 therebetween and'make a highly efficient glazing unit. This window pack 58 is assembled across a window opening 65 in the inner door liner 36 and is held in place by the insulation guard 50. The inner liner contains a reflective surface 66 such as a bright aluminum backed asbestos sheet for the purpose of reflecting radiation back thru the glass pane 83 during high temperature operation.
The inner panel 38 is a hollow member formed of a front panel 67 and a rear panel 69. This rear panel is of rectangular, shallow pane shape having a forwardly directed peripheral flange 71. The front panel 67 is a generally flat construction that extends outwardly beyond the flange 71 of the rear panel, and it is of reflective material such as bright aluminized or chrome plated steel for the purpose of reducing radiation from front panel 67 thru window pack 58. A fibre glass gasket 73 is wrapped over the peripheral edge of the front panel 67, and it bears against the rectangular embossment 47 of the inner door liner 36. This gasket 73 also underlies the peripheral flange 71 of the rear panel 69 so as to establish a sealing gasket surface 75 that is adapted to press against the front flange 77 of the oven liner 14. This inner panel 38 includes a window opening 79 that matches the window openings 54 and 65. This window opening 79 is bounded by two inwardly rolled flanges, 80 of the front panel 67 and 81 of the rear panel 69. Sanwiched between these two flanges 80 and 81 is a single transparent glass pane 83.
This inner panel 38 is filled with thermal insulating material 85 such as fibre glass or the like in the area surrounding the window opening 79. The inner panel 38 is supported from the door proper by a centrally disposed rotatable stub shaft 40 which is formed integral with the front panel 67 of the inner panel 38 and fits through suitable openings 87 in the inner door liner and 88 in the insulation guard, and is prevented from withdrawal therefrom by a pair of parallel shoulders 89 and 90 on the shaft 40. A compression spring 92 is fitted over the shaft 40 and acts between the inner door liner 36 and the adjacent collar 90 to put a biasing force on the shaft 40 tending to pull it within the door and thus exert pressure on the sealing gasket 73 of the inner panel with relation to the inner door liner 36.
The inner panel 38 is shown in FIG. 2 in its normal position when the oven is to be used for cooking. By that is meant the window openings 54, 65 and 79 are aligned, and thus the four glass panes 55, 56, 57 and 83 are aligned for viewing within the oven cavity 13.
Before setting the oven controls to a pyrolytic selfcleaning oven cycle, the oven door 16 must first be opened and the inner panel 38 adjusted by rotating it a half turn about its supporting shaft 40 which thereby inverts the inner panel placing the window opening 79 in the lower half of the door as shown by dotted lines in FIG. 2, which would in turn locate the solid portion of the inner panel 38 across the window openings 54 and 65 thereby establishing an insulated barrier across the window openings in the door to prevent or restrict heat losses through the window opening during the pyrolytic cycle when the oven air temperature would reach near 950F.
Another expedient for holding down the surface temperature of the front face of the oven door 16 is to provide natural convection cooling within the door by creating air inlet openings 95 along the bottom edge of the rearwardly turned flange 41 of the outer door panel 34, as well as air outlet openings 97 in the top edge of the outer door panel, as best seen in FIG. 1. Thus, this cooling air passing upwardly through the door is able to pass between the two glass panes 55 and 56 thereby maintaining relatively low outer glass surface temperatures. This air flow would not be necessary during normal cooking operations because of the four thicknesses of window glass 55, 56, 57 and 83, as well as the presence of the insulation 52 and 85 of the door. If this air flow were to exist during normal cooking operations when the oven door 16 was not sealed nor locked with respect to the oven liner, it would be possible for cooking vapors and oven gases with food soil and grease entrained therein to become deposited on the surfaces of the two panes 55 and 56 which face each other. Over a period of time, this would decrease the visibility through the oven window which would be very objectionable to many meticulous cooks and would require a service call to an appliance service man for disassembling the door and cleaning the glass. This problem can be avoided by the use of pivoted shutters or dampers 100 and 102 which close the free air space above and below the space between the two glass panes 55 and 56 respectively. Both the upper shutter 100 and the lower shutter 102 are connected by hinge means 104 to the insulation guard 50 as can be seen by comparing FIGS. 2 and 3. The lower shutter is joined to the shaft 40 of the rotatable inner panel 38 by a short crank member 106 that is attached to a hook member 108 that is offset from the pivotal axis of the shaft such that when the inner panel 69 is turned the shaft 40 turns and thereby causes the crank member 106 to change the position of the lower shutter 102. When the inner panel 38 is in its normal cooking position of FIG. 2, the lower shutter 102 is in its closed or blocking position. Side link members 109 and 110 join the lower shutter 102 with the upper shutter 100 such that any movement of the lower shutter 102 is reflected in a similar movement of the upper shutter so that they act in unison. Thus, in FIG. 2 both top shutter 100 and bottom shutter 102 are shown in the closed or blocking position. The top shutter 100 is probably of more importance than the bottom shutter because the top shutter also prevents food soil or liquids from being spilled through the air outlet openings 97 in the top edge of the door and reaching the two glass panes 55 and 56.
FIGS. 4 and 5 show a second modification of the present invention wherein identical parts are identified by the same reference numerals. The main distinction between the modification of FIGS. 4 and 5 and the first modification of FIGS. 1, 2 and 3 is the addition ofa rotatable shield 114 such as a reflective aluminum sheet or the like which is'located in the free air space formed between the outer door panel 34 and the insulation guard 50. This shield 114 is fixed to the shaft 40 such that when the inner panel 38 is in its normal cooking position shown in FIGS. 2 and 4, the rotatable shield 114 is shown in its hidden position beneath the window opening 56 in the door. Then when the inner panel 38 is turned a half revolution, this shield 114 will move across the window opening between the first window pane 55 and the second window pane 56 as shown in dotted lines in FIG. 4. There is but a single damper means or shutter 100 in this second modification, and it is the top shutter which is normally in its closed or blocking position of FIG. 4 during normal cooking operations. This shutter is raised when the rotatable shield 114 is moved into the window blocking position shown in dotted lines.
Modifications of this invention will occur to those skilled in this art, therefore, it is to be understood that this invention is not limited to particular embodiments disclosed, but that it is intended to cover all modifications which are within the true spirit and scope of this invention as claimed.
What is claimed as new and desired to be secured by Letters Patent of the United States is:
l. A door construction for a high-temperature oven having an insulated oven cavity formed by a box-like oven liner and a front-opening access door; the invention comprising a door design having an outer door panel, an inner door liner and an insulated inner panel rotatably supported from the inner door liner by pivotal means located generally in the .center of the inner panel, said inner panel being adapted to fit into the front opening of the oven liner, multi-panes of transparent glass assembled in the door between the inner liner and the outer door panel to form a window opening, the inner panel having at least one glass sheet mounted therein to form a window opening, whereby in one position during low-temperature oven operations the window openings are aligned for viewing within the oven cavity, while for high-temperature oven operations the inner panel may first be turned about to a non-aligned position to block the window opening and reduce the heat loss through the door.
2. A door construction as recited in claim 1 wherein there is a free air space provided between the inner liner and outer door panel, with air openings formed adjacent both the bottom and top of the door to permit room air to flow therethrough to restrict the maximum temperatures of the outer surface of the door.
3. A door construction as recited in claim 2 wherein there is a multi-pane window pack supported from the inner door liner and a single window pane supported from the outer door panel, whereby the free air space extends between the window pack and the outer window pane for maintaining relatively low outer glass surface temperatures.
4. A door construction as recited in claim 3 wherein shutter means are associated with the air space between the window pack and the front window pane, and connecting means joining the inner panel with the shutter means so that the shutter means is open during the high temperature oven operations to maintain relatively low front panel surface temperatures and closed during the lower temperature oven operation to prevent inner glass surfaces from becoming soiled during normal cooking operations.
5. A door construction for a high-temperature oven having an insulated oven cavity formed by a box-like oven liner and a front-opening access door; the invention comprising a door design having an outer door panel, an inner door liner and an insulated inner panel rotatably supported from the inner door liner by pivotal means located generally in the center of the inner panel, said inner panel being adapted to fit into front opening of the oven liner with a snug fit, a door gasket carried on the periphery of the inner panel for making a sealing engagement with the front portion of the oven when the door is closed, a single transparent window pane mounted in the inner panel on one side of the pivotal means, a window pack of multiple transparent window panes with a dead-air space therebetween supported from the inner door liner, and a single transparent window pane mounted in the outer door panel, and a free-air space located between the inner door liner and the outer door panel, air openings formed adjacent the bottom and top of the door to permit room air to flow through the air space, the air space having a portion passing between the window pack and the outermost window pane, and a pivotal shield associated with the pivotal means of the inner panel and being 180 out of the phase therewith, so that when the window pane of the inner panel is aligned with the remaining window panes for viewing within the oven cooking cavity during low temperature oven operations, the shield is out of sight within the oven door, while in preparation for high-temperature oven operations the inner panel is first rotated about 180 which blocks the window opening and raises the shield into a blocking position between the window pack and the window pane in the outer door panel.
6. A door construction as recited in claim wherein there is a normally closed movable shutter mounted across the top of the air space between the window pack and the outermost window pane during low temperature oven operations, said damper being raised to an open positon by the movement of the shield into its blocking position.
7. An insulated door construction for use with a hightemperature oven having an oven cooking cavity formed by a box-like oven liner and a front-opening access door, the door having an outer door panel, an inner door liner, an insulation guard disposed in the door between the outer panel and the inner door liner, a layer of insulation between the insulation guard and the inner door liner, the door including a window with multi-panes of transparent glass, an insulated inner panel fastened to the inner door liner by a central shaft that is pivotally mounted within the door, a window formed in the inner panel with at least one transparent glass pane that is adapted to overlie the window in the door, whereby in preparation for a high-temperature operation the inner panel is first adapted to be rotated a half revolution to block the window opening in the door to reduce the heat loss through the door.
8. An insulated door construction as recited in claim 7 wherein the area in front of the insulation guard is a free air space, openings formed adjacent the bottom and top of the door and communicating with the free air space to create a natural air flow therethrough to restrict the maximum temperature of the outer surface of the door.
9. An insulated door construction as recited in claim 8 wherein the free air space is provided with shutter means to impede the air flow with relation to the window glass so as to prevent soiling of the window glass during cooking operations, said shutter means being connected to the inner panel so that when the panel is positioned to block the window opening the shutter means will be opened to allow the natural air flow through the air space of the door.
10. An insulated door construction as recited in claim 8 with the addition of a shield positioned in the free air space and connected to the shaft of the inner panel, the shield in one position being hidden when the window opening of the inner panel is aligned with the window opening of the door, the shield being in a position to block the window opening of the door when the inner panel is turned to block the latter window opening.
11. An insulated door construction as recited in claim 10 with a normally closed shutter means arranged above the window glass in the free air space to impede the air flow during low temperature operations, the movement of the shield to a position to block the window opening also causing the shutter means to be deflected to an open position to allow the natural air flow.