A high-frequency heating apparatus includes a supply source for supplying high-frequency energy into a conductive heating chamber. Two pairs of stirring blades mounted on a rotary shaft inside the chamber are positioned relatively to the supply source so that a substantial portion of the radiated energy is intercepted and reflected by the blades to afford more uniform heating of materials within the chamber. The generally elongated stirring blades are mounted tangentially of the circumference of an imaginary circle lying in a plane normal to the rotary shaft and concentric with the shaft axis. The blades of each pair lie in parallel planes inclined at an angle of 45.degree. with respect to the plane of the imaginary circle and thus are oppositely inclined with respect to the axis of the rotary shaft. As the blades are rotated, high-frequency energy from the source, in a first mode, is reflected from the upper surface of one of the blades of the pair in a centrifugal direction and, in a second mode, from the upper surface of the other blade in a centripital direction toward the first blade of the pair and reflected downwardly from the lower surface of the latter. Continuous rotation of the shaft effects a continuously alternating sequence of the modes thus established by each pair of blades.
A microwave oven having a field stirrer comprising a circular sheet metal disc having a plurality of radial slots arranged about its periphery. The ends of the segments thus formed are preferably bent at different angles. The slots and segments together form semiresonant elements to which the energy from the microwave generator couples directly and then is reradiated by the rotating disc which acts as a moving virtual energy source. The disc is rotated so that the segments pass by the microwave energy coupling aperture for the oven. The oven combination produces a more uniform microwave energy distribution within the oven cavity and also improves the matching of the microwave generator to the cavity load so that the generator operates in the load region most suitable to the application.
The field stirrer herein has an upwardly concave pan shape and is formed as a sheet metal stamping. It has a central planar section and a surrounding section comprising a plurality of circumferentially arranged segments with planar surfaces, the segments being shaped like equilateral trapezoids. The surrounding section has three circumferentially spaced segment groups in which the individual segments thereof slope upwardly at an angle of approximately 45.degree. relative to the planar section. Each of the segment groups includes at least three of the segments which are laterally joined by folded edges. There are also three individually mounted segments arranged alternately relative to the three segment groups which slope upwardly at an angle of approximately 27.degree. relative to the central planar section. At least one segment in each segment group has a rectangularly shaped opening with a rectangularly shaped flap extending vertically downwardly from the upper edge of said opening. The stirrer includes a central hub member and at least one rectangularly shaped opening in the planar section spaced from the hub member and extending in a generally tangential direction relative thereto. A rectangularly shaped flap is at the inner edge of the opening and the flap is inclined towards the hub member to form an acute angle relative to said central planar section.
An agitation device for high-frequency electromagnetic waves in a high-frequency oven has at least one pair of planar rotary blades of metal extending in radially opposite directionsfrom a hub part and fabricated, together with the hub part, from a single strip of sheet metal into a staggered or stepped shape in which the blades respectively lie in mutually different offset planes and present minimum profiles with respect to air resistance during rotation, the blades thereby rotating through mutually different paths and imparting effective field agitation to prevent occurrence of a high-frequency standing wave and to render uniform the distributive state of the high-frequency waves applied to the oven interior.
A microwave oven in which the heating chamber is defined by an upper portion serving as a door opening upwards and a lower portion forming the oven chamber lower portion for constituting, upon closure of the door, one complete heating chamber, in one side of which heating chamber, microwave assembly and stirrer members are advantageously incorporated for simplification of the heating chamber construction and compact size of the oven, with the stirrer members which are rotated by the passage of cooling air thereover being disposed in positions symmetrical with respect to the central vertical axis of the heating chamber for efficient microwave energy distribution and consequent uniform heating of the object to be heated.
A microwave oven in which the oven chamber is defined by upper and lower portions each generally triangular in section and which is provided with efficient microwave reflecting and distributing arrangements. The lower portion is defined by a main casing and the upper portion, which includes the oven chamber front and top walls, is defined by a concave portion in a door assembly which is hinged along a rear edge portion and may be pivoted upwards to open positions and downwards to a closed position. When in a completely opened position the door assembly exposes the top and front of the oven, whereby insertion or removal of food may be effected through the top or front of the oven, and the oven permits convenient use when placed at different levels.
