Device and method for cooktop fire mitigation

• US 9,132,302 B2
• Filed: 03/15/2013
• Issued: 09/15/2015
• Est. Priority Date: 08/14/2012
• Status: Active Grant

• Current Assignee: Primaira, LLC
• Original Assignee: Primaira, LLC
• Inventors: Luongo, Wade, Benedek, Karen, Carbone, Philip C.
• Primary Examiner(s): CAMPBELL, THOR S
• Application Number:
  US13/840,280
• Publication Number:
  US 20140048293A1
• Time in Patent Office: 914 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: A62C 3/006 for kitchens or stoves
• CPC Class Codes: F24C 3/122 on stoves
• CPC Class Codes: F24C 3/126 on ranges
• CPC Class Codes: F24C 7/083 on tops, hot plates
• CPC Class Codes: F24C 7/087 of electric circuits regulating heat
• CPC Class Codes: F24C 7/088 on stoves
• CPC Class Codes: H05B 3/22 non-flexible
• CPC Class Codes: H05B 3/746 Protection, e.g. overheat cutoff, hot plate indicator
• CPC Class Codes: H05B 3/76 Plates with spirally-wound heating tubes

Abstract

A device for limiting the temperature of cookware on a cooktop to a threshold level that corresponds to an oil ignition temperature. The device includes a temperature sensor that is positioned adjacent a bottom of the cookware on the cooktop. A control device in combination with each of the temperature sensor and the cooktop monitors the temperature and adjusts a heating element of the cooktop as needed to avoid cooking oil ignition. The temperature sensor can be a spring loaded temperature sensor to ensure and/or absorb contact with the cookware.

Claims

1. A device for avoiding an overshoot of a temperature inside a cookware on a cooktop by limiting a bottom temperature of the cookware, the device comprising:

a temperature sensing clement measuring a surface temperature adjacent a bottom of the cookware on the cooktop; and

a control device in combination with each of the temperature sensing element and the cooktop, the control device having a control algorithm modifying a power level of the cooktop as a function of both a sensed temperature adjacent the bottom of the cookware and a rate of change of the sensed temperature by reducing the power level at a lower temperature when the rate of change of the sensed temperature is greater than or equal to a threshold value than when the rate of change of the sensed temperature is less than the threshold value, and the control algorithm controlling the power level as a function of the sensed temperature, the rate of change of the sensed temperature, and a change in a slope of a temperature/time curve and increasing the power level when the slope of the temperature/time curve is negative.

2. A device in accordance with claim 1, wherein the temperature sensing element comprises a spring loaded sensor.

3. A device in accordance with claim 1, wherein the temperature sensing element comprises a thermistor or a resistance temperature detector.

4. A device in accordance with claim 1, wherein the temperature sensing element comprises a convex cover that maintains contact with the cookware on the cooktop.

5. A device in accordance with claim 1, wherein during use of the cookware the algorithm prevents the temperature of the cookware from exceeding an oil ignition temperature.

6. A device in accordance with claim 1, wherein the cooktop is an electric coil cooktop including a source of electric power and an electric resistance heating element that has thermal inertia such that the temperature of the cookware can continue to rise even after power to the element has been reduced or removed, the temperature sensing element is in direct contact with the bottom of the cookware, and the control device is in controlling combination with an electric relay of the source of electric power to reduce the power in order that the bottom temperature remains below an oil ignition temperature and above temperatures required for standard cooking techniques.

7. A device in accordance with claim 1, wherein the cooktop is an electric coil cooktop including a source of electric power and an electric resistance heating element that has thermal inertia such that the temperature of the cookware can continue to rise even after power to the element has been reduced or removed, the temperature sensing element is in direct contact with the bottom of the cookware, and the control device is in controlling combination with an electric infinite switch of the cooktop to reduce the power in order that the bottom temperature remains below an oil ignition temperature and above temperatures required for standard cooking techniques.

8. A device in accordance with claim 1, wherein the cooktop is a gas fired cooktop including a source of gaseous fuel, a gas-fired burner, and a gas flow line containing a gas flow of the gaseous fuel to the gas-fired burner, the temperature sensing element is in direct contact with the bottom of the cookware, and the control device is in controlling combination with the gas flow line to reduce the gas flow in order that the bottom temperature remains below an oil ignition temperature and above temperatures required for standard cooking techniques.

9. A device in accordance with claim 8, wherein the control device lowers the gas flow to a set input rate that does not turn a cooktop flame off entirely when controlling the cookware temperature to a threshold level to avoid oil ignition.

10. A device in accordance with claim 8, wherein the control device is in controlling combination with a valve of the gas flow line.

11. A device in accordance with claim 10, wherein the valve directs the gas flow to a bypass line with a defined diameter.

12. A device in accordance with claim 1, wherein the cooktop is a smoothtop electric cooktop including a source of power, a glass ceramic cooktop surface with thermal inertia such that the temperature of the cookware can continue to rise even after power to the element has been reduced or removed, and an electric heat source below the cooktop surface, the temperature sensing clement is mounted to an under surface of the glass ceramic cooktop surface, and the control device controls power to the electric heat source in order that the bottom temperature remains below an oil ignition temperature and above temperatures required for standard cooking techniques.

13. A device in accordance with claim 12, wherein during use of the cookware the algorithm prevents the temperature of the cookware from exceeding the oil ignition temperature.

14. A device in accordance with claim 1, wherein the power level of the heating element is shut off completely, reduced from a starting power level or set to a defined duty cycle.

15. A device in accordance with Claim 1, wherein the control algorithm increases the power level when a slope of a temperature/time curve is negative even if the sensed temperature is above a second threshold value.

16. A device in accordance with Claim 1, wherein the increase in the power level is for a defined interval.

17. A device in accordance with claim 1, wherein the surface temperature is of a protective cover of a temperature sensor or is a glass ceramic cooktop.

18. A device in accordance with claim 1, wherein the power level is of a power source that is an electric coil, an electric radiant element, or a gas-fired burner.