Patent US3819903A successfully refreshed from Google Patents.
US3819903A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ceramic cooktop with a spiralled heating coil element assembly
Assignee: Whirlpool Corp
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Filing: 1973-06-28
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Granted: 1974-06-25
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Expires: 1993-06-28
Abstract
Abstract A smooth glass-ceramic cooktop for ranges and the like having one or more heating elements disposed below the cooktop for heating cooking utensils and the like supported on the cooktop. Each one of the heating elements is arranged in a unique spiral configuration providing substantially uniform heating of the cooktop surface area disposed superjacent thereto. The spacing between the spiral coil turns of the respective heating elements decreases as a function of the angle thereof from the inner end of the spiral in a novel manner to provide the desired uniform heating effect.
Inventors
- 👤 H Frick
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 15:22
CPC Classifications
H; H05; H05B; H05B3/00; H05B3/68; H05B3/74; H05B3/748; H05B3/76
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
136 words
In a range structure having a glass-ceramic cooktop for surface cooking operations, a surface heating element assembly mounted below said cooktop for heating a utensil placed on said cooktop, said element comprising: an insulative heater support having a top surface spaced adjacent said cooktop; a groove in the heater support top surface defining a spiral, said spiral having an inner end, an outer end and a plurality of turns between the inner end and the outer end; and a uniformly coiled resistance wire heating coil element positioned in said groove to extend from said inner end to said outer end, said element being arranged for connection to a source of power for producing heat energy, the radial spacing between successive turn portions of the groove and coil decreasing from the inner end to the outer end.
Claim 2
Dependent Claim
136 words
In a range structure having a glass-ceramic cooktop for surface cooking operations, a surface heating element assembly mounted below said cooktop for heating a utensil placed on said cooktop, said element comprising: an insulative heater support having a top surface spaced adjacent said cooktop; a groove in the heater support top surface defining a spiral, said spiral having an inner end, an outer end and a plurality of turns between the inner end and the outer end; and a uniformly coiled resistance wire heating coil element positioned in said groove to extend from said inner end to said outer end, said element being arranged for connection to a source of power for producing heat energy, the radial spacing between successive turn portions of the groove and coil decreasing from the inner end to the outer end.
Claim 3
Dependent Claim
15 words
The range structure as claimed in claim 1 wherein said cooktop comprises a glass cooktop.
Claim 4
Dependent Claim
14 words
The range structure as claimed in claim 1 wherein said radial spacing uniformly decreases.
Claim 5
Dependent Claim
23 words
The range structure as claimed in claim 3 wherein said radial spacing decreases as a function of the angle of said turn portions.
Claim 6
Dependent Claim
83 words
The range structure as claimed in claim 1 wherein said spiral groove has a radius defined by the following formula: R C1 -C2 theta - C3 theta 2 . . . where theta is the angle of the coil turn expressed in radians, the angle being measured from a starting point by tracing along the centerline of the coil spiral; C1, C2 and C3 are constants; and R is the radial distance in inches from the coil center to the coil turn centerline.
Claim 7
Dependent Claim
30 words
The range structure as claimed in claim 1 wherein said spacing along a preselected radius decreases in the following steps: (a) .875 inch, (b) .750 inches, and (c) .687 inch.
Claim 8
Dependent Claim
55 words
The range structure as claimed in claim 1 wherein the spiral groove has a radius defining the centerline of the groove constructed as a function of a constant, plus a constant times the angle of the point from the start of the spiral, minus a constant times the square of said angle of the point.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-24 | 1977-12-24 | 1978-06-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-24 | 1981-12-24 | 1982-06-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-24 | 1985-12-24 | 1986-06-25 | $7700.00 | Window Closed / Lapsed |