Induction-based food holding/warming system and method

• US 9,585,202 B2
• Filed: 05/20/2011
• Issued: 02/28/2017
• Est. Priority Date: 05/20/2011
• Status: Active Grant

• Current Assignee: Cooktek Induction Systems, LLC (Middleby Corporation)
• Original Assignee: Cooktek Induction Systems, LLC (Middleby Corporation)
• Inventors: Graber, Warren S, Visher, Robert J, Metz, Reinhard
• Primary Examiner(s): Angwin, David
• Assistant Examiner(s): LAFLAME JR, MICHAEL A
• Application Number:
  US13/112,221
• Publication Number:
  US 20120294990A1
• Time in Patent Office: 2,111 Days
• Field of Search: 994/51, 336/15, 336/65, 336/117, 219/112, 219/162, 219/200, 219/600, 219/108, 219/632, 219/608, 219/618, 219/621, 219/620, 219/624, 219/630, 219/622, 219/627
• US Class Current: 1/1
• CPC Class Codes: A47J 36/24 Warming devices
• CPC Class Codes: A47J 36/2483 with electrical heating means
• CPC Class Codes: H05B 2213/07 Heating plates with temperature control means
• CPC Class Codes: H05B 6/062 for cooking plates or the like
• CPC Class Codes: H05B 6/105 using a susceptor
• CPC Class Codes: H05B 6/12 Cooking devices
• CPC Class Codes: H05B 6/1209 induction cooking plates or the like and devices to be used in combination with them
• CPC Class Codes: H05B 6/36 Coil arrangements
• CPC Class Codes: Y02B 40/00 Technologies aiming at improving the efficiency of home appliances, e.g. induction cooking or efficient technologies for refrigerators, freezers or dish washers

Abstract

A system and method for holding and warming food held in pans or trays having a low relative magnetic permeability, such as 300-series stainless steel, using induction heating.

Claims

1. A system for holding and warming food, comprising:

a container for holding and warming food, the container consisting of 300-series stainless steel; and

an induction heating unit with an induction heating circuit for induction heating the container, the induction heating circuit including an induction coil having 40 or more turns of a 120 volt coil, wherein the induction coil operates at a current of 5-11 amperes.

2. The system of claim 1, wherein the induction coil comprises 14 gauge wire.

3. The system of claim 1, further comprising a device for measuring the temperature of the container.

4. The system of claim 3, wherein the measured temperature is used in a closed loop control to limit and maintain the temperature of the container at a desired value.

5. The system of claim 4 wherein the measured temperature is used to generate a ramped inverter power profile facilitating lateral heat transfer in the container.

6. The system of claim 3, wherein the device for measuring the temperature of the container is mounted beneath the container in a manner to facilitate maintaining contact with the container despite variations in shape or size of the container.

7. The system of claim 1, wherein the container is induction-heated in a manner that minimizes internal heat generation within the induction heating unit and thereby enables induction heating without the need for a cooling fan.

12. The system of claim 1, wherein the induction coil has an inductance of at least 250 μ

Henries.

13. The system of claim 3, wherein the device for measuring the temperature of the container comprises a resistive thermal device.

8. A system for holding and warming food, comprising:

a container for holding and warming food, the container consisting of 300-series stainless steel; and

an induction heating circuit for induction heating the container, the induction heating circuit including an induction coil having 75 or more turns of a 240 volt coil, wherein the induction coil operates at a current of 4-8 amperes.

9. The system of claim 8, further comprising a device for measuring the temperature of the container.

14. The system of claim 9, wherein the device for measuring the temperature of the container comprises a resistive thermal device.

17. The system of claim 8, wherein the induction coil has an inductance of at least 800 μ

Henries.

10. An apparatus for warming food in a 300-series stainless steel container, the apparatus comprising:

an induction heating unit for heating the container by induction heating, the induction heating unit including an inverter power circuit, power circuit controls, and an induction coil, the induction coil having 40 or more turns of a 120 volt coil and an inductance of at least 250 μ

Henries, wherein the induction coil operates at a current of 5-11 amperes, and wherein the container consists of 300-series stainless steel.

11. The apparatus of claim 10, wherein the inverter power circuit includes a resonant capacitor.

18. The apparatus of claim 10, wherein the induction coil comprises 14 gauge wire.

15. An apparatus for warming food in a 300-series stainless steel container, the apparatus comprising:

an induction heating unit with an induction heating circuit for induction heating the container, the induction heating circuit including an induction coil having 75 or more turns of a 240 volt coil and an inductance of at least 800 μ

Henries, wherein the induction coil operates at a current of 4-8 amperes, wherein the container consists of 300 series stainless steel.

16. The apparatus of claim 15, wherein the induction coil comprises 18 gauge wire.

19. A system for holding and warming food, comprising:

a container for holding and warming food, the container consisting of 300-series stainless steel; and

an induction heating unit with an induction heating circuit for induction heating the container, the induction heating circuit including an induction coil having an inductance of at least 250 μ

Henries for a 120 volt coil, wherein the induction coil operates at a current of 5-11 amperes.

20. The system of claim 19, wherein the coil has 40 or more turns.

21. The system of claim 19, wherein the coil comprises 14 gauge wire.

22. A system for holding and warming food, comprising:

a container for holding and warming food, the container consisting of 300-series stainless steel; and

an induction heating unit with an induction heating circuit for induction heating the container, the induction heating circuit including an induction coil having an inductance of at least 800 μ

Henries for a 240 volt coil, wherein the induction coil operates at a current of 4-8 amperes.

23. The system of claim 22, wherein the coil has 75 or more turns.

24. The system of claim 22, wherein the coil comprises 18 gauge wire.