General Electric Company

Matthew S Miller

Louis H Fitzmayer

James E Staats

Stephen Michael Bakanowski

A forced air convection oven includes a cooking compartment and an air heating chamber adjacent to one wall of the cooking compartment. An air circulating fan and an air heater are mounted in a central section of the chamber. An elongated section of the chamber extends from the fan along the compartment wall and has an uniformly decreasing cross section area. There is an inlet opening in the compartment wall aligned with the fan and a plurality of outlet openings uniformly spaced apart along the compartment wall communicating with the elongated chamber section. Each outlet opening has a cross sectional area equal to the cross section area of the end of the elongated section adjacent to the fan divided by the number of outlet openings.

Convection oven tapered air heating chamber

An improved excitation system for a microwave oven employing a circular rotating disk antenna configured to radiate peripherally from its outermost edge to provide backgound radiation in the oven cavity. Primary microwave energy radiation is emitted from a pair of transverse radiating slots formed in the disk antenna. A first slot is positioned radially outwardly relative to the second slot. The first slot alternately functions as a relatively strongly coupled series and shunt radiating slot and the second slot concurrently alternately functions as a moderately coupled shunt and series slot with each quarter revolution of the disk antenna. Both slots are louvered for improved coupling to the load being heated in the cavity.

Rotating slot antenna arrangement for microwave oven

A wire rack construction designed to be used in a microwave oven in spaced relationship with the flat bottom wall of the oven. The wire rack is provided with upwardly and downwardly projections which are arranged such that when the rack is placed on the flat bottom wall of the oven the rack will tilt at a steep angle to thereby discourage its use in the oven when it is not arranged in its design position relative to the bottom wall.

Microwave oven rack design

An excitation system for a microwave cooking appliance includes a waveguide along one wall arranged to support a standing wave therein, with an array of apertures spaced along the length of the waveguide to couple energy from the waveguide to the cooking cavity. A phase shifting device periodically shifts the phase of the standing wave between a first phase relationship and a second phase relationship. The array of radiating apertures is configured to support a first and a second substantially stationary radiating pattern when the first and second phase relationships, respectively, are established for the standing wave in the waveguide. Each radiating pattern at the cooking plane has regions of relatively high energy density interspersed wth regions of relatively low energy density, with the high energy regions of one pattern overlying low energy regions of the other, such that by periodically switching between patterns the uniformity of the time-averaged energy density at the cooking plane is enhanced.

Dynamic bottom feed for microwave ovens

An excitation system for a microwave cooking appliance which employs a low profile rotating disk to enhance time-averaged uniformity of energy distribution within the resonant cooking cavity. A rectangular waveguide couples energy from the magnetron to the cooking cavity. A circular opening is formed in a common wall between the waveguide and the cooking cavity, which opening is essentially blocked by a rotatable metallic disk overlapping the opening on the cavity side of the wall. An elongated radiating slot is formed on the disk for coupling energy from the waveguide to the cooking cavity extending generally transverse to the radius of the disk. The axis of rotation of the disk is longitudinally spaced an odd integral multiple of quarter guide wavelengths from the short circuit termination of the waveguide, and the longitudinal axis of the radiating slot is radially spaced approximately one quarter guide wavelength from the axis of rotation of the disk, thereby orienting the slot alternately as a series slot at a maximum wall current point and a shunt slot at a maximum field point with each quarter revolution of the disk. During each complete rotation of the disk, the slot passes through four maximum energy coupling positions with less optimum coupling positions interspersed therebetween, thereby enhancing time-averaged energy distribution uniformity in the cavity by periodically varying the radiation intensity of the slot and its position in the cavity during each rotation of the disk.

A microwave oven cavity excitation system which introduces circularly-polarized electromagnetic wave energy into a cooking cavity through a plurality of feed points appropriately phased to provide a concentrated beam. The relative phasing of the feed points is varied as a function of time to steer the concentrated beam to sweep the interior of the cavity, improving the time-averaged energy distribution. One form of phase shift element disclosed is a dielectric vane rotated by airflow through a feed waveguide within which the dielectric vane is rotatably mounted. As a result of the circular polarization, standing waves in the direction of one of the cavity dimensions are minimized, and the amount of energy reflected back to the generator may be reduced.

Microwave oven cavity excitation system employing circularly polarized

A mode stirrer drive assembly in which the mode stirrer blades are rotated by the force of air against a drive fan. The blades of the drive fan are curved to form convex surfaces which are arranged to face into the flow of air across the drive fan. During rotation an upward force is thereby exerted on the assembly which lifts the assembly off of a thrust bearing and thereby reduces frictional losses and noise and improves performance and efficiency.

Growing community of inventors

Louisville, KY, United States of America

Matthew S Miller