Microwave cooking appliance incorporating electric heating element
AssigneeMaytag Corporation
InventorsDavid W. Brinker, Robert Z. Whipple, Jr.
Life of this patent
Estimating the term…
Abstract
A microwave cooking appliance includes a sheathed resistive electric heating element including an outer portion, an inner portion and a cross-over portion electrically interconnecting the outer and inner portions. The heating element is arranged in a cooking chamber of the microwave cooking appliance in a manner which effects an impedance characteristic of the cooking chamber. The cross-over portion is arranged such that the heating element acts like an RF antenna moving a microwave energy field to portions of the cooking chamber in which low electric fields occur. In this manner, the broil element helps increase the operational efficiency of the cooking applaince by minimizing any hot and cold spots within the cooking chamber.
Claims17
A microwave cooking appliance comprising:
- a cooking chamber including an interior surface and an opposing, exterior surface;
- a toroidal-shaped waveguide, defining an inner diameter and an outer diameter, mounted on the exterior surface of the cooking chamber and including at least one opening leading into the cooking chamber;
- a microwave generator for emitting a microwave energy field of a defined wavelength into the waveguide;
- and
- an electric heating element including an outer portion extending along the interior surface of the cooking chamber, an inner portion extending about the inner diameter of the waveguide, and a cross-over portion electrically interconnecting the outer and inner portions, wherein the heating element is adapted to radiate heat into the cooking chamber during at least select portions of a cooking operation.
In a combination microwave, convection and radiant cooking appliance having a cooking chamber including an upper surface, an electric heating element comprising:
- an outer portion, including a pair of terminal ends, supported by and extending about a first portion of the upper surface of the cooking chamber;
- an inner portion arranged within the outer portion and extending about a second portion of the upper surface of the cooking chamber;
- and
- a cross-over portion electrically interconnecting the outer and inner portions, said cross-over portion being adapted to tune an impedance characteristic of the cooking chamber, wherein the cross-over portion is positioned to effect standing wave patterns of microwaves by directing the microwaves to areas of low electric energy thus reducing the occurrence of high and low electric fields within the cooking chamber and contributing to the overall efficiency of the cooking appliance.
A method of tuning an impedance characteristic of a microwave cooking chamber having an interior upper surface comprising:
- providing a microwave energy source to supply a microwave energy field to the cooking chamber;
- providing a sheathed resistive electric heating element having an outer portion, an inner portion and a cross-over portion electrically interconnecting the outer and inner portions;
- supporting the sheathed resistive electric heating element on the interior upper surface of the cooking chamber;
- arranging the cross-over portion such that the heating element acts as an RF antenna moving portions of the microwave energy field to certain sections of the cooking chamber.
Dependencies are inferred from the claim text.