Abstract: An air flow system for a combination microwave and electric convection oven wherein a single motor drives two fans to generate a movement of air in an oven cavity and a movement of air in an electrical component compartment. The fan moving the air in the electrical component compartment is positioned between the fan moving the air in the oven cavity and the motor to act as a thermal barrier and to protect the motor from the heated air in the oven cavity. A portion of the air in the electrical component compartment may be diverted to the oven cavity and subsequently exhausted from the oven. Simultaneously, an electrical heater may be de-energized with the result that the air in the oven cavity is heated by resistive losses from components in the electrical component compartment. By combining this diverted air flow with a minimum of microwave energy, many types of foods may be effectively dehydrated in a substantially shorter than normal period of time.

Abstract: Microwave ovens typically have an oven cavity and a feed system for supplying microwaves through a feed opening into the cavity. Such ovens are inproved by providing a field stirrer rotatably mounted over and covering the feed opening. The field stirrer is a single conductive plate having a single radiating slot in the plate exposing only a portion of the feed opening to the cavity through the slot at any position of the plate during its rotation. The slot is in the shape of an arc or other shape which is tangentially longer than it is radially wide. The plate also has a plurality of wings, fins, or vanes outside the feed opening. The vanes and slot are arranged so that electrically identical positions of the plate occur only every full circle of rotation by virtue of bilateral symmetry at most. The plate is spaced from the feed opening and into the cavity by a sufficient distance to permit flow of microwave energy beneath the plate for distribution around the periphery of the plate and by the vanes.

Abstract: A utensil handle assembly for a utensil suitable for use in a microwave oven combining the advantages of metal with the advantages of plastic. A split metal ring is tightly drawn around the utensil and fastened together. A plastic handle is connected to the already fastened metal ring through a connecting area. The connecting area is made up of a series of wedges pressed together and bonded to form a permanent connection.

Abstract: A package heat exchange system is disclosed having a burner positioned in the central plenum of a substantially cylindrical heat exchanger. A fuel-air mixture is supplied through a blower supplied with fuel from a pressure regulator which requires a somewhat less than atmospheric pressure at the blower inlet to draw gaseous fuel through the pressure regulator. A solenoid-operated, positive pressure valve in the main gasline provides the heat exchanger with an enriched gas mixture on ignition. The enrichment valve automatically closes after 30 seconds of operation. Air for combustion is drawn through a series of orifice plates positioned between the regulator and the blower. The fuel-to-air ratio may be altered by changing the size and/or number of the holes in one of the orifice plates. Further, one of the orifice plates may be deformable so as to form a seal, and to supply a predetermined quantity of air to the burner for combustion.

Abstract: A microwave oven having a directional rotating antenna axially supported on an axis of one wall of a microwave oven cavity of the microwave oven which provides circularly symmetric uniform energy distribution of microwave energy within the microwave oven cavity and consistent heating of a product in the microwave oven cavity. The directional rotating antenna includes a two-by-two array of antenna elements where each element is an end driven half-wavelength resonating antenna element supported by a length of conductor perpendicular to the wall of the microwave oven cavity. A parallel plate transmission line connects to each of the supports, four of which join at a junction which connects to a cylindrical probe antenna. The probe antenna is excited by microwave frequency currents of a waveguide adjacent to the wall of the microwave oven cavity. The directional antenna is rotated by a moving stream of air circulated through the microwave oven cavity.

Abstract: An orifice plate for metering a mixture of fuel and air to a blower for supply of the mixture to a burner positioned in a central plenum of a heat exchange system, the present plate further provides the sole sealing structure necessary for sealing conduit members which communicate the blower with a fuel regulator. The present orifice plate can be configured with apertures of differing size and number to facilitate field alternation of the heat capacity of the system and to allow rapid conversion of the system to alternate fuels without the need for removing and installing additional sealing structure. The ratio of fuel to air present in the mixture which is burned in the system is controlled by the size and/or number of apertures formed in the orifice plate.

Abstract: An adjustable safety interlock is disclosed for microwave ovens or other high voltage electrical apparatus. The interlock is actuated by the movement of a counterbalance arm when the door is opened. The amount of movement necessary to actuate the interlock is altered by changing the position of the interlock switch relative to the counterbalance arm. The interlock switch is pivotally mounted on the side of the apparatus for this purpose. Pivotal movement of the interlock towards and away from the counterbalance arm is achieved by a finely threaded bolt. The bolt is biased in the direction of greater safety by a compression spring. The interlock is readily accessible during production and thereafter only by authorized personnel.

Abstract: A microwave cooker digitally programmed in any of a plurality of different cycles whose digital programs are selected from a front panel display. Programs include a cook cycle, a defrost cycle, and/or a defrost and cook cycle, in which a body of refrigerated food to be heated is subjected to microwave energy for a predetermined time in the oven, and then allowed to set for a predetermined time to allow heat produced in the food body by said microwave energy to at least partially disperse throughout the body thereby equalizing the temperature of different food body regions and then applying additional microwave energy for a predetermined time to cook said food body.

Abstract: A digitally programmed microwave oven having a microwave generator energized by a high voltage power supply connected to an alternating current source through mechanically actuated oven door interlock switches, with the power supply regulating the current supplied to the microwave generator to compensate for peak voltage variations in the alternating current source by resonating the output of the power supply in the region of the frequency of the alternating current source in which the power supply is initially energized by a semiconductor switch actuated by a computer to accurately control the time of initial supply of power to said power supply at a point which minimizes the input current surge to said resonant circuit by actuating said semiconductor switch at a time substantially .pi./2 radians of said frequency after the zero voltage point of said alternating current source.

Abstract: A compact heating and cooling system in which air ducts are connected to a heat exchanger system through which a coolant fluid from a condensing unit or a heating fluid from a compact water heater is selectively directed by a control circuit so that the system may be mounted outside a building to be heated and/or cooled.

Abstract: A microwave oven control system in which the average microwave power may be selected by selecting different duty cycles of a cyclically closing semiconductor switch controlling the AC power supplied to a microwave magnetron anode power supply which has a saturable high voltage transformer with input current surges to said power supply being minimized by turning on said switch in the region a voltage peak of said AC power and with the cycle time of said switch being greater than the AC power cycle time but being substantially less than the thermal response time of a food body being cooked by microwave energy so that changing the duty cycle can change the power applied to the food body rapidly in the event that undesired results such as boiling over or burning of the food body are observed.

Abstract: A microwave oven having a door with a peripheral microwave seal structure which is fabricated from one or more die formed aluminum parts and solid dielectric inserts to form a resonant transmission line structure with peripheral oven wall portions, with transmission of microwave energy in the seal around the periphery of the door prevented by impedance discontinuities, and leakage of microwave energy through the seal is prevented by impedance mismatch or resonant choke action of the seal structure, and the size of a notch in a solid dielectric insert in a quarter wavelength shorted branch line of the seal is selected for different production runs of the oven to compensate for dimensional changes in different die stamped metal parts or assembled door structures due to assembly jig changes, stamping die wear or assembly procedures.

Abstract: A heat exchange system is provided having first and second heat exchangers connected to one another. A burner supplies products of combustion to the first heat exchanger. Fluid heated in the first heat exchanger is pumped to the second heat exchanger. A blower forces air over the second heat exchanger to heat the air. An electric heater is provided in heat exchange relationship with the first heat exchanger. The electric heater maintains the temperature of the fluid in the first heat exchanger above the effective dew point of the flue gas in the heat exchanger.

Abstract: A microwave oven having a door formed from metal structural elements which are welded together and coated with a nonconductive coating. Solid dielectric portions of the microwave seal choke are inserted into the choke regions of the door seal, and slotted portions of one of the steel structural elements are then deformed to form the choke and to lock the solid dielectric portions in place.

Abstract: An energy seal for microwave oven apparatus having a first energy responsive structure disposed adjacent to a first energy propagation path commencing at the peripheral gap between the oven access opening and door assembly walls. A second structure responsive to the oven operating frequency is disposed adjacent to the output end of a second energy propagation path communicating with said first path. In one embodiment a conductive frame trim member forms a second choke-type structure together with underlying door assembly components of a nonconductive plastic material. The energy seal structures may also incorporate a slotted wall arrangement of the type disclosed in U.S. Pat. No. 3,767,884 to Osepchuk et al, issued Oct. 23, 1973.

Abstract: A freezer-refrigerator unit is provided with exterior ice service through the front of the cabinet. The unit has a panel forming a portion of the front closure of the freezer compartment and hinged at its lower edge to swing outwardly. Behind the panel is an ice tray, and the tray is supplied with ice cubes from an automatic ice maker located in the freezer compartment.

Abstract: A package heat exchange system having a burner positioned in the central plenum of a first heat exchanger and supplied with a fuel-air mixture through a blower supplied with fuel through a pressure regulator which requires a negative pressure at the blower input to draw gaseous fuel through the pressure regulator. Thermal energy is transferred from the first heat exchanger to a second heat exchanger or from the second heat exchanger to a third heat exchanger by pumped fluids and transferred to or from the second heat exchanger and air blown through the second heat exchanger to heat or cool the air with blowing of the air, operation of the burner and heating of the first heat exchanger when the burner is not operating being used to maintain the temperature of the surface of the first heat exchanger which contacts the products of combustion of the burner above the dew point of the products of combustion.

Abstract: A safety interlock system is disclosed for microwave ovens or other high voltage electrical apparatus incorporating sensor means for detecting any malfunction. Means are provided for interrupting line input power or actuating a failure indicating device or a combination of both. Thermally actuated means, such as bimetallic or meltable elements, as well as circuit breakers, relays and fuses are described. The sensor means are associated with each of the interlocks and do not carry regular equipment load current until such time as a malfunction of the companion interlock occurs. Replacement of the faulty equipment by authorized personnel and manual resetting of the interrupt or indicating means before the oven is energized again reduce the risk of accidental radiation, electrical shock or damage to the apparatus. .Iadd.