Oven ventilating system

Abstract

A baking and broiling oven having cooling air channels surrounding an insulated oven liner. The oven liner includes a front access door with a cooling air channel extending upwardly therethrough. A suction fan is located near the top of the oven to induce an air flow through all of the air channels for reducing the exterior surface temperatures of the oven. A constriction is formed in the gap above the oven door to create an aspirator effect to increase the amount of cooling air flow through the door.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to baking and broiling ovens, and particularly to a forced air cooling system for maintaining the outer surfaces of the oven below predetermined maximum temperatures. This invention is primarily directed to means for increasing the flow of cooling air up through the front door of the oven.

2. Description of the Prior Art

Air cooling systems have been built into oven designs for many years, as is shown by U.S. Pat. No. 3,121,158 of Bohdan Hurko, which is assigned to the same assignee as the present invention. Such cooling systems are particularly useful with ovens that are provided with a pyrolytic self-cleaning oven cycle where the temperatures within the cooking cavity may reach as high as 950.degree.F. High temperature limits for the outer surfaces of the oven are even more difficult to maintain when a self-cleaning oven is built into a wall, rather than being a free-standing appliance. An air cooling system for a built-in wall oven is described in U.S. Pat. No. 3,310,046 of George A. Scott and James K. Newell, Jr., which is also assigned to the assignee of the present invention. Cooling air channels have also been provided in the oven doors for permitting natural convection air currents to flow up through the door, and thereby reduce the exterior temperatures of the door. One such door design is shown in U.S. Pat. No. 3,736,916 of James A. White, which is also assigned to the present assignee.

The principal object of the present invention is to provide a ventilating system for a baking and broiling oven using suction fan means to propel the cooling air around the oven liner, as well as through the oven door.

A further object of the present invention is to provide an oven ventilating system of the class described in combination with an aspirating action created across the top edge of the oven door for improving the efficiency of heat transfer between the outer door panel and the cooling air passing up through the door.

SUMMARY OF THE INVENTION

The present invention, in accordance with one form thereof, relates to an oven construction having a heated cooking cavity formed by insulated walls. There is an outer oven cabinet surrounding the insulated oven walls, and cooling air channels formed within the oven cabinet so that air flowing through the channels will reduce the outer surface temperatures of the cabinet. The oven door also has a vertical air cooling channel. There is a suction fan located in the top portion of the oven cabinet for producing a strong draft of air in the oven cabinet. This top air channel communicates with the vertical air channel in the door so that the suction fan augments the natural convection air currents through the door. Moreover, a constriction is formed in the door gap above the top edge of the door so as to increase the velocity of ambient air flow over the door and thereby reduce the static pressure at that location so that the vertical air flow through the door is further augmented by an aspirator effect created by the constriction.

BRIEF DESCRIPTION OF THE DRAWING

This invention will be better understood from the following description taken in conjunction with the accompanying drawing, and its scope will be pointed out in the appended claims.

The drawing is a right side elevational view of an electric, built-in wall oven with some parts broken away and others in cross-section to show the general nature of the oven construction, as well as the air flow pattern created by the suction fan around the outside of an insulated oven liner as well as up through the oven door. A constriction is formed in the door gap along the top edge of the door for creating an aspirator effect to further improve the heat transfer efficiency between the outer door panel and the cooling air passing up through the door.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning now to a consideration of the drawing, there is shown a built-in wall oven 10 having an oven cooking cavity 12 formed by a box-like oven liner 14 with a front opening that is adapted to be closed by a hinged, drop-door 16. The particular oven shown is an electric oven, as is clear from the presence of a lower bake element 17 and an upper broil element 18 adjacent the top wall of the oven liner 14. However, this invention is not limited to use with electrically heated ovens; it could just as well be used with a gas heated oven, both of which are conventional in this art. A layer of thermal insulating material 20 of fiber glass or the like is placed around the outside of the oven liner 14 for retaining as much as possible of the oven heat within the cooking cavity 12. An oven cabinet construction 22 encircles the insulated oven liner 14, but it is spaced outwardly therefrom to form cooling air channels 24, at least up the two sides of the oven, and up the back of the oven, and across the top of the oven. At the bottom of the oven there may be a slightly different construction. The bottom may be left somewhat open, except for a pair of spaced runners or beams 26 on which the oven would be supported during assembly in the factory, or display in the appliance dealer's showroom, or for supporting in a hollow wall structure. In any event, cooling air is allowed to flow beneath the bottom of the insulated oven liner.

The outer oven cabinet 22 has opposite side walls 28 which do not extend down to cover the runners 26, but they are shortened so that air may flow underneath the lower edge of the side walls and rise up through the air channels 24 formed between the side wall 28 and the layer of insulation 20 that surrounds all of the walls of the oven liner. At the front of the oven, beneath the oven door 16, is an open grill work or screen 30 of elongated shape that extends from one side to the other of the oven cabinet and serves as a primary air inlet means for the air cooling channels 24 within the oven cabinet 22. Additional air inlet openings may be formed in the front frame of the outer oven cabinet 22 that surrounds the front door opening along the two sides of the door, but these are not shown and they do not form a necessary part of this invention.

The cooling air channel 24 above the oven liner is provided with a small electric motor 32 and a blower wheel 34 supported from a vertical shaft of the motor. The blower wheel is provided with a metal housing or shroud 36 having an inlet opening 38 adjacent the bottom thereof such that when the motor 32 is energized the blower wheel 34 will draw air up into itself and discharge it through a tangential duct 40 out through an exhaust vent 42, either at the top or back wall of the oven cabinet. This explains the air flow pattern of drawing room air into the air inlet 30 beneath the oven door 16 and across the bottom of the oven liner and up through the air channels 24 at the three sides of the oven liner and across the top air channel 24 into the blower wheel 34. Attention will now be directed to the construction of the oven door 16. This door is generally of sheet metal construction having three main elements; an outer door panel 50, an inner door liner 52, and a small central inner panel 54 that is supported from the inner door liner. The outer door panel 50 is of shallow pan configuration by virtue of the fact that it has a slightly rearwardly facing peripheral flange 56. The inner door liner 52 is also of shallow pan configuration, and it is of mating or telescopic construction with the outer door panel 50 by virtue of the fact that it has a slight front-facing peripheral flange 58 which slips into the peripheral flange 56. Suitable screw fasteners (not shown) hold the inner door liner 52 to the outer door panel 50 near the top edge of the door in conjunction with an oven door handle 60 that is located along the front face of the door near the top thereof. At the bottom of the door there is a tab and slot connecting relationship at 62 along most of the bottom edge of the door which prevents separation of the outer door panel 50 from the inner door liner 52 unless the above-mentioned screw fasteners at the top of the door are first removed.

The inner door liner 52 includes a generally rectangular outward embossment 64 which is adapted to project somewhat into a recessed front frame 66 of the outer oven cabinet 22 which surrounds the oven liner 14. The box-like oven liner 14 has an outwardly turned front flange 68 which bears against the front frame 66, and the oven liner is pulled rearwardly into the oven cabinet 22 by tension means (not shown) such as J-bolts or the like, as is standard practice in this art. The central inner panel 54 is also of shallow pan shape with a slight front-facing peripheral flange 70, and this inner panel is adapted to project into the throat of the oven liner 14 in the manner of a close-fitting plug. The flat face of the embossment 64 of the inner door liner 52 is formed with a large opening or cut-out for accommodating the flanged portion 70 of the inner panel 54 therein, so that the inner panel substantially fills the opening. This opening is also provided with an inwardly turned front-facing peripheral flange 72 which closely parallels the peripheral flange 70 of the inner panel. Wrapped around the peripheral flange 70 near the edge thereof is a strip gasket 74 of thermal insulating material such as woven fiber glass or the like. This gasket 74 has an enlarged exposed edge 76 that is adapted to seal against the front flange 68 of the oven liner 14 when the door 16 is closed. This strip gasket 74 is sandwiched between the flange 70 and the generally parallel flange 72 to serve as a thermal break between the inner panel 54 and the inner door liner 52. Fastening screws 78 hold the inner panel 54 assembled to the inner door liner 52.

This particular oven door 16 happens to be provided with an oven window 90, although the present invention does not require a window in the door. The outer door panel 50 has a window opening 92 with a trim frame 94. Over this window frame is sealed a first pane 96 of high temperature glass or the like. The inner panel 54 is also provided with a window opening 98 having a front-facing flange 100 over which is sealed a double window pack 102 comprising a pair of glass panes 104 and 106 which are held apart by a peripheral spacer frame 108, and assembled together by a channel member 110 which extends completely around the window pack and is fastened together at its two ends to form a complete sub-assembly, as is standard in this art. Surrounding the window pack 102 is a layer of thermal insulating material 112 such as fiber glass or the like. This insulation in conjunction with the double window pack 102 serves as a suitable thermal insulating means to retain the heat within the oven cooking cavity 12. The insulation 112 is confined by an insulation guard 114 which is a sheet metal plate that is fastened to the flange 72 of the inner door liner by screw fasteners 116. Of course, this insulation guard 114 also has a window opening in the vicinity of the double window pack 102 so as not to obscure the view through the window.

A vertical air channel 120 is present within the oven door 16, and it is formed at the bottom by the presence of a sheet metal panel 122 that closely overlies the outer door panel 50 in the area beneath the window 90. Air inlet openings 124 are located along the bottom portion of the rearwardly turned flange 56 to communicate with the narrow air channel 120. The plate 122 also extends up the two sides of the window and rises from the top of the window to the top edge of the door. The plate 122 in the area along the bottom edge of the window is turned rearwardly as at 126 to allow the cooling air to pass into the area between the first pane 96 and the central pane 104. This cooling air is more turbulent in this area because of the relatively wide area between the glass panes. This cooling air from the window area again passes up in front of the panel 122 as at 120. Air outlet openings 132 are formed in the top portion of the rearwardly turned flange 56 such that the cooling air rising through the air channel exits through the outlet openings 132.

The front wall of the top air channel 24 serves as a control panel 135 on which are mounted a plurality of oven control components 137 which may be manually adjusted as by use of a knob 139 for controlling the various heating circuits, the oven temperature, a clock-timer, all of which are conventional in this art. The control panel 135 is located generally directly above the oven door 16. Air inlet openings 141 are located in the bottom wall 156 of the top air channel 24 near the front of the oven and generally directly overlying the air outlet openings 132 along the top edge of the oven door 16. Thus, when the suction fan 34 is energized, it not only draws air into the air channels 24 through the air inlet openings 30 beneath the bottom edge of the oven door, but it also tends to pull air up through the door through the air inlet openings 124 along the bottom edge of the door and out the air outlet openings 132 and through the air inlet openings 141 into the blower wheel 34. Accordingly, there is not only natural convection air currents through the door but also air is drawn up through the door by means of the suction fan 34.

It is preferred that this cooling air movement through the door not be allowed to reach the control components 137 because this air picks up heat energy from the oven door and would tend to contribute to higher temperatures of the control components. Accordingly, partitions 143 and 145 are positioned beneath the components and across the back side of the components to form a closed area 147 housing the control components and separating them from the cooling air path that passes through the oven door.

In order to cool down the control components 137, air inlet openings 149 may be formed along the top edge of the control panel 135, and air outlet openings 151 may be formed in the bottom partition 143 near the rear partition 145 such that when the suction fan 34 is energized cooling air will be drawn through the control housing 147 and combined with the cooling air coming from the door to pass out through the suction fan 34.

A constriction 155 is formed in the door gap above the top edge of the door a slight amount forward of the air outlet openings 132 in the door so as to increase the velocity of ambient air flow over the top edge of the door caused by the suction fan and thereby reduce the static pressure just above the air outlet openings 132, so that the vertical air flow through the door is augmented by an aspirator effect created by this constriction. This constriction 155 may be formed by creating a raised formation 157 along the top edge of the door just in front of the air outlet openings 132, or the constriction could be formed by having a pair of formations 157 on the door and 159 on the bottom surface of the bottom wall 156 forming the top air channel 24. A preferred embodiment would have the spacing or height of the constriction 155 equal to about one-half of the height of the gap between the top edge of the door and the bottom surface of the wall 156 of the top air channel. This would give optimum aspirating effects.

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 the 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.

Claims

What is claimed as new and is desired to be secured by Letters Patent of the United States is:

1. An oven having a cooking cavity formed by a box-like oven liner and a front-opening access door, heating means for supplying heat energy to the cooking cavity, thermal insulating means surrounding the oven liner and also included within the said door for retaining the oven heat within the cooking cavity, an outer oven cabinet surrounding the insulated oven liner, cooling air channels formed within the oven cabinet around the oven liner as well as within the door for reducing the outer surface temperatures of the cabinet and door as room ambient air flows through the air channels, the door having air inlet openings along its bottom edge and air outlet openings along its top edge to create a vertical flow of natural convection air currents, the outer oven cabinet having air inlet means for introducing air into the cooling air channels of the cabinet, and an oven control panel located above the oven door and mounted on the oven cabinet; the invention comprising a suction fan located in the air channel above the oven liner and behind the control panel for drawing air up through the air channels within the oven cabinet, said top air channel also having air inlet means beneath the control panel and generally in alignment with the air outlet openings in the top edge of the door, a constriction formed in the door gap above the top edge of the door a slight amount forward of the air outlet openings in the door so as to increase the velocity of ambient air flow over the top edge of the door and thereby reduce the static pressure just above the said air outlet openings in the door so that the vertical air flow through the door is augmented by an aspirator effect created by the said constriction.

2. An oven as recited in claim 1 wherein there is a raised formation on the top edge of the oven door just in front of the air outlet openings, and extending substantially from one side of the door to the other, this raised formation cooperating with the adjacent bottom surface of the top air channel to form the said constriction, both said air outlet openings in the top edge of the door and the air inlet openings in the top air channel beneath the control panel extending substantially from one side of the door to the other.

3. An oven as recited in claim 2 wherein the air channel within the oven door is a relatively narrow channel created by a vertical panel closely spaced behind the front panel of the door, so that this narrow air channel in the door retards turbulence of the air within the air channel and contributes to a swift laminar flow to improve the efficiency of the heat transfer from the front door panel to the cooling air stream passing up through the door.

4. An oven as recited in claim 2 wherein partitions are formed in conjunction with the control panel to prevent the sweep of air entering the top air channel through the air inlet openings from reaching the components associated with the control panel.

5. An oven as recited in claim 4 wherein the said partitioned area behind the control panel is open to the outside of the oven and is open to the said suction fan so that when the suction fan is operated cooling air is drawn through the partitioned area so as to increase the useful life of the control components.