THREE DIMENTIONAL INDUCTION RETHERMALIZING STATION AND CONTROL SYSTEM

• US 20140157998A1
• Filed: 12/12/2012
• Published: 06/12/2014
• Est. Priority Date: 12/12/2012
• Status: Active Grant

• Current Assignee: Vollrath Company LLC
• Original Assignee: Vollrath Company LLC
• Inventors: Roever, Peter, Wojcik, John, Wang, Yang
• Granted Patent: US 9,307,862 B2
• Time in Patent Office: Days
• US Class Current: 99/483
• CPC Class Codes: A47J 36/2483 with electrical heating means
• CPC Class Codes: H05B 6/06 Control, e.g. of temperature, of power
• CPC Class Codes: H05B 6/065 using coordinated control of multiple induction coils
• 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 6/1245 with special coil arrangements
• CPC Class Codes: H05B 6/1272 with more than one coil or coil segment per heating zone

Abstract

A rethermalizing station includes a well defined by an exterior wall, a food pan configured to be inserted into the well and to hold a food item, a first induction coil surrounding the exterior wall of the well, the first induction coil configured to warm the food item via inductive heating of the food pan, a first temperature sensor configured to detect a temperature of the food pan, and a control unit coupled to the first induction coil and the first temperature sensor, the control unit configured to control the first induction coil in response to the temperature of the food pan detected by the first temperature sensor such that temperature of the food pan is maintained at a targeted temperature.

Claims

1. A rethermalizing station for rethermalizing or warming food items, the rethermalizing station comprising:

a well defined by an exterior wall;

a food pan configured to be inserted into the well and to hold a food item;

a first induction coil surrounding the exterior wall of the well, the first induction coil configured to warm the food item via inductive heating of the food pan;

a first temperature sensor configured to detect a temperature of the food pan; and

a control unit coupled to the first induction coil and the first temperature sensor, the control unit configured to control the first induction coil in response to the temperature of the food pan detected by the first temperature sensor such that temperature of the food pan is maintained at a targeted temperature.

2. The rethermalizing station of claim 1, wherein the well has a well perimeter and extends for a well depth;

and

wherein the first induction coil has a coil perimeter larger than the well perimeter and extends for a coil depth not greater than the well depth.

3. The rethermalizing station of claim 2, wherein the well perimeter and the coil perimeter are both circular.

4. The rethermalizing station of claim 2, wherein the well perimeter and the coil perimeter are both polygons.

5. The rethermalizing station of claim 4, wherein the well perimeter and the coil perimeter are both the same polygon.

6. The rethermalizing station of claim 1, further comprising:

a biasing member coupled to the first temperature sensor to bias the first temperature sensor away from a bottom of the well so that the first temperature sensor contacts a bottom of the food pan to detect the temperature of the food pan.

7. The rethermalizing station of claim 6, further comprising:

a second temperature sensor configured to detect a temperature of the food pan at an elevation different than the first temperature sensor, the second temperature sensor coupled to the control unit; and

an indicator to indicate a need for user attention to the food item;

wherein the control unit is further configured to determine a temperature difference between the temperature of the food item detected by the first temperature sensor and the temperature of the food item detected by the second temperature sensor and to turn on the indicator when the detected temperature difference exceeds a targeted temperature difference, thereby indicating the need for user attention to the food item.

8. The rethermalizing station of claim 7, wherein the second temperature sensor is one of a plurality of second temperature sensors coupled to the exterior wall of the well, each of the plurality of second temperature sensors is positioned to contact the food pan to detect the temperature of the food pan, and each of the plurality of second temperature sensors coupled to the control unit.

9. The rethermalizing station of claim 8, wherein the first and second temperature sensors are thermistors.

10. The rethermalizing station of claim 1, wherein the control unit is configured to control the induction coil by varying a power output of the induction coil.

11. The rethermalizing station of claim 10, wherein the control unit is configured to control the induction coil without using an on/off duty cycle.

12. The rethermalizing station of claim 10, wherein the control unit is configured to vary the power output of the induction coil by varying a current supplied to the induction coil.

13. The rethermalizing station of claim 12, wherein the control unit is configured to vary the current supplied to the induction coil along a current range of about 0.75 amps to about 6.8 amps.

14. The rethermalizing station of claim 10, wherein the control unit is configured to vary the power output of the induction coil along a power output range of 8 watts to 800 watts.

15. The rethermalizing station of claim 1, further comprising:

a second induction coil positioned below a bottom surface of the well, the second induction coil electrically coupled in series with the first induction coil and configured to warm the food item via inductive heating of the food pan;

wherein the control unit is coupled to the second induction coil and configured to control the second induction coil in response to the temperature of the food pan detected by the first temperature sensor such that temperature of the food pan is maintained at the targeted temperature.

16. The rethermalizing station of claim 15, wherein the first induction coil includes a first number of turns and the second induction coil includes a second number of turns less than the first number of turns.

17. A rethermalizing station, comprising:

a three-dimensional induction coil; and

processing electronics configured to vary the output power of the induction coil in response to a comparison of a detected temperature and a targeted temperature.

18. The rethermalizing station of claim 17, wherein the processing electronics are configured to implement a low temperature mode, an over temperature mode, a keep warm mode, and a burning prevention mode in response to the comparison of the detected temperature and the targeted temperature.

19. The rethermalizing station of claim 18, wherein the processing electronics cause the induction coil to operate at a maximum output power of the induction coil in the low temperature mode.

20. The rethermalizing station of claim 19, wherein the processing electronics cause the induction coil to operate at a minimum output power of the induction coil in the over temperature mode.

21. The rethermalizing station of claim 20, wherein the processing electronics cause the induction coil to operate at a variable output power between the maximum output power of the induction coil and the minimum output power the induction coil in the keep warm mode.

22. The rethermalizing station of claim 21, wherein the processing electronics cause the induction coil to operate at an output power less than the maximum output power in the burning prevention mode.

23. The rethermalizing station of claim 18, wherein the processing electronics cause the induction coil to operate at a variable output power between a maximum output power of the induction coil and a minimum output power the induction coil in the keep warm mode.

24. The rethermalizing station of claim 17, wherein the processing electronics are configured to implement a rethermalizing mode and a warming mode.

25. The rethermalizing station of claim 24, wherein the processing electronics cause the induction coil to operate at a maximum output power of the induction coil in the rethermalizing mode.

26. The rethermalizing station of claim 25, wherein the processing electronics cause the induction coil to operate at a variable output power between a maximum output power of the induction coil and a minimum output power the induction coil in the warming mode.

27. A rethermalizing station for rethermalizing or warming food items, the rethermalizing station comprising:

a well defined by an exterior wall and a bottom;

a food pan including a bottom and a sidewall, the food pan configured to be inserted into the well and to hold a food item;

a three-dimensional side induction coil surrounding the exterior wall of the well, the side induction coil configured to warm the food item via inductive heating of the food pan;

a bottom induction coil proximate to the bottom of the well, the bottom induction coil configured to warm the food item via inductive heating of the food pan;

a bottom temperature sensor configured to detect a temperature of the bottom of the food pan;

a side temperature sensor configured to detect a temperature of the sidewall of the food pan; and

a control unit configured to control the power output of the side induction coil and the bottom induction coil in response to the temperature of the food pan detected by at least one of the bottom temperature sensor and the side temperature sensor such that temperature of the food pan is maintained at a targeted temperature.

28. The rethermalizing station of claim 27, wherein the side induction coil includes a first number of turns and the bottom induction coil includes a second number of turns less than the first number of turns.

29. The rethermalizing station of claim 27, wherein the control unit is configured to control the side induction coil and the bottom induction coil without using an on/off duty cycle.

30. The rethermalizing station of claim 27, further comprising:

a biasing member coupled to the bottom temperature sensor to bias the bottom temperature sensor away from the bottom of the well so that the bottom temperature sensor contacts the bottom of the food pan;

wherein the side temperature sensor contacts the sidewall of the food pan.