Back to results
US 4,029,926 AGranted
Work coil for use in an induction cooking appliance
AssigneeRoper Corporation
InventorBuddy Julian Austin
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneeRoper Corporation
InventorBuddy Julian Austin
Estimating the term…
An induction cooking appliance for operation at ultrasonic frequencies and including an improved work coil coupled in a solid state inverter circuit to generate an ultrasonic frequency magnetic field which is coupled to a metallic utensil through a non-electrically conductive cooktop. Coil losses are minimized, and coupling efficiency increased by forming the coil of solid conductor wound in a loose spiral, with the pitch of the spiral being related to the radial thickness of the conductor by a factor falling within a predetermined range. The loosely wound coil is held in a grooved dielectric support which insures proper turn spacing for the life of the appliance and which is immune to high temperatures which may be developed during operation of the coil. Means are provided under the support to minimize stray radiation and limit inductance variations which might otherwise result from nearby metallic members. Means are provided for holding the coil adjacent the underside of the cooktop for optimum coupling and to utilize heat developed in the coil. The loosely wound configuration is advantageously fabricated by methods including interleaving the coil conductor with an insulative strip. Alternatively, an open coil may be formed by winding the conductor on a frusto-conical mandrel whose degree of taper is related to the desired pitch of the coil, and compressing the coil into a planar configuration.
In a solid state induction cooking appliance for producing heat in a metallic utensil by means of an ultrasonic frequency magnetic field, said appliance including a solid state inverter having a resonant circuit comprising a capacitor and inductor, an improved work coil in said appliance for generating the ultrasonic frequency magnetic field and coupling said field to the utensil comprising a solid single strand conductor, said conductorbeing wound in a single layer spiral to form a substantially flat coil, the winding pitch being related to the radial thickness of the conductor by a thickness-to-pitch ratio in the range between 0.3 and 0.7, said work coil being connected as the inductor in said inverter for resonating with said capacitor at an ultrasonic frequency whereby resonant exchange of energy between said work coil and capacitor causes said work coil to generate said ultrasonic frequency magnetic field.
In a solid state induction cooling appliance for producing heat in a metallic utensil by means of an ultrasonic frequency magnetic field, said appliance including a solid state inverter having a resonant circuit comprising a capacitor and inductor, an improved work coil in said appliance for generating the ultrasonic frequency magnetic field and coupling said field to the utensil comprising a solid single strand conductor of rectangular cross-section, said conductor being wound in a single layer spiral to form a substantially flat coil, the longer dimension of the rectangular conductor cross section establishing the height of the coil, the winding pitch being related to the radial thickness of the conductor by a thickness-to-pitch ratio in the range between 0.1 and 0.7, said work coil being connected as the inductor in said inverter and having sufficient inductance for resonating with said capacitor at an ultrasonic frequency whereby resonant exchange of energy between said work coil and capacitor causes said work coil to generate said ultrasonic frequency magnetic field.
In an induction cooking appliance having a solid state inverter including a resonant capacitor and inductor for transforming a d.c. potential into current pulses of ultrasonic frequency, an improved work coil in said appliance for conducting said current pulses to generate an ultrasonic frequency magnetic field, said work coil comprising a solid single strand conductor of rectangular cross section, said conductor being wound in a single layer to form a spiral, said spiral being loosely wound with the radial thickness of the conductor being related to the pitch of the winding by a ratio in the range between 0.1 and 0.7, said coil being connected as the resonant inductor in said solid state inverter and having sufficient inductance to cause said inverter to resonate at said ultrasonic frequency.
A work coil in an induction cooking appliance, said appliance including a solid state inverter including a capacitor and said work coil resonant therewith for producing ultrasonic frequency current pulses in the work coil thereby to generate an ultrasonic frequency magnetic field, and a substantially non-metallic cooktop for supporting a metallic utensil over the work coil, said work coil comprising:
Dependencies are inferred from the claim text.