Combination microwave and thermal self-cleaning oven with an automatic venting arrangement

In a combined microwave and thermal self-cleaning oven of the type having a plurality of operating modes including a microwave mode and a self-cleaning mode, and comprising an oven cavity formed by a box-like oven liner having an access opening formed in one wall thereof, a door for closing said opening, a sealing gasket to seal the space between said liner and door when said door is closed, an exhaust passageway for venting air from said cavity, a catalytic oxidation unit interposed in said exhaust passageway for decomposing gases generated in the self-cleaning mode, and a restricted air inlet passageway defined by a gap through said sealing gasket and configured to meter only a regulated amount of outside air into said cavity to facilitate the controlled combustion of exhaust gases in the oxidation unit when the oven is operating in the self-cleaning mode, the improvement comprising:

• sensing means for sensing the relative humidity of air exiting the cavity through the exhaust passageway;
• blower means including a blower outlet positioned adjacent said gap operative when energized to increase the flow rate of outside air into the cavity through said gap;
• blower control means responsive to said sensing means and operative to energize said blower means only when the sensed relative humidity level exceeds a predetermined threshold level indicative of excessive humidity in the cavity;
• and
• means for enabling energization of said blower means only when operating in the microwave mode or the microwave/bake mode;
• whereby when operating in the microwave mode or microwave/bake mode, humid air is purged from the cavity thereby preventing a steam buildup in the cavity.