Induction heating pizza delivery systems

• US 6,444,961 B2
• Filed: 04/05/2001
• Issued: 09/03/2002
• Est. Priority Date: 05/19/1998
• Status: Expired due to Term

• Current Assignee: TSI SUB LLC
• Original Assignee: Thermal Solutions Incorporated (Rtx Corporation)
• Inventors: May, David E., Heine, William W., Wolters, Robert E. Jr., Clothier, Brian L., Ablah, Amil J.
• Primary Examiner(s): Leung, Philip H.
• Application Number:
  US09/826,782
• Publication Number:
  US 20010019051A1
• Time in Patent Office: 516 Days
• Field of Search: 219/621, 219/622, 219/623, 219/624, 219/620, 219/647, 219/649, 219/387, 219/626, 219/627, 219/667, 99D/IG.14, 994/51, 126/246, 126/375, 126/400, 126/275
• US Class Current: 219/622
• CPC Class Codes: H05B 2213/06 Cook-top or cookware capable of communicating with each other
• CPC Class Codes: H05B 6/06 Control, e.g. of temperature, of power

Abstract

Temperature self-regulating food delivery systems are provided having a magnetic induction heater (32, 126) and an associated food container (76, 124) equipped with an essentially permanent ferromagnetic heating element (82, 100, 128). The heater (32, 126) and heating elements (82, 100, 128) are designed so as to heat the element (82, 100, 128) to a user-selected regulation temperature when the elements (82, 100, 128) are coupled with the heater'"'"'s magnetic field, and to maintain the temperature in the vicinity of the regulation temperature indefinitely temperature regulation is a heating achieved by periodically determining at least two parameters of the heaters resonant circuits related to the amplitude of the resonant current passing therethrough during heating and responsively altering the field strength of the magnetic field. Preferably, the value of the resonant circuit amplitude and the rate of change of the amplitude are determine.

Claims

1. A pizza temperature maintenance system, comprising:

an induction heating unit including a generator operable to generate a magnetic field, and a and a holder having a base plate which is generally square in plan configuration and presents a periphery having four margins, with upstanding walls adjacent at least three of the margins,

said unit further including a resonant circuit with an induction coil;

a flexible bag adapted to hold a pizza container, said flexible bag comprising top and bottom panels, a sidewall panel interconnecting the top and bottom panels, there being an open end between the top and bottom panels allowing access to the interior of the bag, a closure flap secured to one of the top and bottom panels for selectively closing said open end, and an internal pocket within the bag;

an induction heatable element located within said internal pocket,

said bag being sized to be placed upon said holder base plate in close proximity with said upstanding walls, with the element being located for coupling with said magnetic field to thereby heat the element;

a sensor operably coupled with said magnetic field generator in order to detect the presence of said bag on said base plate to thereby permit generation of said magnetic field, said sensor selected from the group consisting of photosensors land press-type switches;

a visual display operably coupled with said unit for generating a visual indication relating to the operation of said generator, when said bag is placed upon said holder base plate; and

a temperature controller for controlling the temperature of said element about a regulation temperature, including a detector operable to detect an induction heater circuit parameter related to the amplitude of the resonant current passing through the resonant circuit and control circuitry operable to alter the magnetic field strength of said magnetic field in response to the magnitude, or rate of change of said magnitude of said detected parameter.

2. The system of claim 1, said element comprising a body formed of ferromagnetic material.

3. A pizza temperature maintenance system, comprising:

an induction heating unit including a generator operable to generate a magnetic field, and a holder having a base plate which is generally square in plan configuration and presents a periphery having four margins, with upstanding walls adjacent three of the margins,

said unit further including a resonant circuit with an induction coil;

a flexible bag adapted to hold a pizza container, said flexible bag comprising top and bottom panels, a sidewall panel interconnecting the top and bottom panels, there being an open end between the top and bottom panels allowing access to the interior of the bag, a closure flap secured to one of the top and bottom panels for selectively closing said open end, and an internal pocket within the bag;

an induction heatable element located within said internal pocket,

said bag being sized to be placed upon said holder base plate in close proximity with said upstanding walls, with the element being located for coupling with said magnetic field to thereby heat the element;

a sensor operably coupled with said magnetic field generator in order to detect the presence of said bag on said base plate to thereby permit generation of said magnetic field, said sensor selected from the group consisting of photosensors and press-type switches;

a visual display operably coupled with said unit for generating a visual indication relating to the operation of said generator, when said bag is placed upon said holder base plate; and

a temperature controller for controlling the temperature of said element, including a detector operable to detect an induction heater circuit parameter related to the amplitude of the resonant current passing through the resonant circuit and control circuitry operable to alter the magnetic field strength of said magnetic field in response to the magnitude, or rate of change of said magnitude of said detected parameter.

4. The system of claim 3, said element comprising a body formed of ferromagnetic material.

5. A pizza temperature maintenance system, comprising:

an induction heating unit including a generator operable to generate a magnetic field, and a holder having a base plate which is generally square in plan configuration and presents a periphery having four margins, with upstanding walls adjacent at least three of the margins,

said unit further including a resonant circuit with an induction coil;

a flexible bag adapted to hold a pizza container, said flexible bag comprising top and bottom panels, a sidewall panel interconnecting the top and bottom panels, there being an open end between the top and bottom panels allowing access to the interior of the bag, a closure flap secured to one of the top and bottom panels for selectively closing said open end, and an internal pocket within the bag;

an induction heatable element located within said internal pocket,

said bag being sized to be placed upon said holder base plate in close proximity with said upstanding walls, with the element being located for coupling with said magnetic field to thereby heat the element;

a visual display operably coupled with said unit for generating a visual indication relating to the operation of said generator, when said bag is placed upon said holder base plate; and

a temperature controller for controlling the temperature of said element about a regulation temperature, including a detector operable to detect an induction heater circuit parameter related to the amplitude of the resonant current passing through the resonant circuit and control circuitry operable to alter the magnetic field strength of said magnetic field in response to the magnitude, or rate of change of said magnitude of said detected parameter.

6. The system of claim 5, said element comprising a body formed of ferromagnetic material.

7. A pizza temperature maintenance system, comprising:

an induction heating unit including a generator operable to generate a magnetic field, and a holder having a base plate which is generally square in plan configuration and presents a periphery having four margins, with upstanding walls adjacent three of the margins,

said unit further including a resonant circuit with an induction coil;

a flexible bag adapted to hold pizza container, said flexible bag comprising top and bottom panels, a sidewall panel interconnecting the top and bottom panels, there being an open end between the top and bottom panels allowing access to the interior of the bag, a closure flap secured to one of the top and bottom panels for selectively closing said open end, and an internal pocket within the bag;

an induction heatable element located within said internal pocket,

said bag being sized to be placed upon said holder base plate in close proximity with said upstanding walls, with the element being located for coupling with said magnetic field to thereby heat the element;

a visual display operably coupled with said unit for generating a visual indication relating to the operation of said generator, when said bag is placed upon said holder base plate; and

a temperature controller for controlling the temperature of said element, including a detector operable to detect an induction heater circuit parameter related to the amplitude of the resonant current passing through the resonant circuit and control circuitry operable to alter the magnetic field strength of said magnetic field in response to the magnitude, or rate of change of said magnitude of said detected parameter.

8. The system of claim 7, said element comprising a body formed of ferromagnetic material.

9. A pizza temperature maintenance system, comprising:

an induction heating unit including a generator operable to generate a magnetic field, comprising a circuit with an induction coil;

an enclosure adapted to hold a pizza container;

a heating assembly carried by said enclosure including a component which is induction heatable by said magnetic field; and

a control assembly cooperable with said heating assembly in order to control the temperature of the heating assembly during heating of the heating assembly, said control assembly including a detector operable to detect a circuit parameter related to the amplitude of the current passing through said circuit, and control circuitry operable to alter the magnetic field strength of said magnetic field in response to the magnitude, or rate of change of said magnitude, of said detected parameter.

10. The system if claim 9, said enclosure comprising a flexible bag.

11. The system of claim 9, said component being at least partially formed of ferromagnetic material.

12. The system of claim 9, said detector operable to detect the amplitude of said current.

13. A pizza temperature maintenance system, comprising:

an induction heating unit including a generator operable to generate a magnetic field, comprising a circuit with an induction coil;

an enclosure adapted to hold a pizza container;

a heating assembly carried by said enclosure including a component which is induction heatable by said magnetic field; and

a control assembly cooperable with said heating assembly in order to control the temperature of the heating assembly during heating of the heating assembly, said control assembly including a detector operable to detect an induction heater circuit parameter whose magnitude is dependent upon the impedance presented by the heating assembly when the assembly is magnetically coupled with said magnetic field, and control circuitry operable to alter the magnetic field strength of said magnetic field in response to the magnitude, or rate of change of said magnitude, of said detected parameter.

14. The system of claim 13, said enclosure comprising a flexible bag.

15. The system of claim 13, said component being at least partially formed of ferromagnetic material.

16. The system of claim 13, said detector operable to detect the amplitude of the current passing through said circuit.

17. A food delivery system, comprising:

a food-holding container including a heating assembly comprising a heatable component;

a magnetic induction heater including a magnetic field generator for generating a magnetic field, and an induction heater circuit,

said container being configured for placement in an operative position adjacent said heater so that, when a magnetic field of sufficient strength is generated by said field generator, said component is heated; and

a temperature control assembly operable to maintain said component in a heated condition by periodically raising the field strength of said field from a low level to a higher level, and maintaining the field strength at said higher level for a period of time, while said container remains in said operative position,

said temperature control assembly including a detector operable to detect an induction heater circuit parameter whose magnitude is at least in part dependent upon the impedance presented by the container when the container is in said operative position thereof, and control circuitry operable to maintain the magnetic field strength of said magnetic field at said higher level in response to the magnitude, or rate of change of the magnitude, of said detected parameter.

18. The system of claim 17, said parameter being the amplitude of the current passing through said induction heater circuit.

19. The system of claim 18, said container configured to receive a pizza box containing pizza.

20. The system of claim 17, said temperature control assembly also operable to periodically lower the field strength of said magnetic field from said higher level to said lower level while said container remains in said operative position.

21. A food delivery system, comprising:

a food-holding container including a heating assembly comprising a heatable component;

a magnetic induction heater including a magnetic field generator for generating a magnetic field, and a resonant induction heater circuit,

said container being configured for placement in an operative position adjacent said heater so that, when a magnetic field of sufficient strength is generated by said field generator, said component is heated; and

a temperature control assembly operable to maintain said component in a heated condition by periodically raising the field strength of said field from a low level to a higher level, and maintaining the field strength at said higher level for a period of time, while said container remains in said operative position,

said temperature control assembly including a detector operable to detect an induction heater circuit parameter whose magnitude is at least in part dependent upon the amplitude of the current passing through the resonant circuit when the container is in said operative position thereof, and control circuitry operable to maintain the magnetic field strength of said magnetic field at said higher level in response to the magnitude, or rate of change of the magnitude, of said detected parameter.

22. The system of claim 21, said parameter being the amplitude of the current passing through said induction heater circuit.

23. The system of claim 21, said temperature control assembly also operable to periodically lower the field strength of said magnetic field from said higher level to said lower level while said container remains in said operative position.

24. The system of claim 21, said container configured to receive a pizza box containing pizza.

25. A heating method, comprising the steps of:

providing a food-holding container including a heating assembly comprising a heatable component;

providing a magnetic induction heater including a magnetic field generator for generating a magnetic field, and an induction heater circuit;

placing said container in an operative position adjacent said heater so that, when a magnetic field of sufficient strength is generated by said field generator, said component is heated; and

maintaining said component in a heated condition by periodically raising the field strength of said field from a low level to a higher level, and maintaining the field strength at said higher level for a period of time, while said container remains in said operative position,

said temperature-maintaining step including the steps of detecting an induction heater circuit parameter whose magnitude is at least in part dependent upon the impedance presented by the container when the container is in said operative position thereof, and maintaining the magnetic field strength of said magnetic field at said higher level in response to the magnitude, or rate of change of the magnitude, of said detected parameter.

26. The method of claim 25, said parameter being the amplitude of the current passing through said induction heater circuit.

27. The method of claim 25, further including the step of periodically lowering the field strength of said magnetic field from said higher level to said lower level while said container remains in said operative position.

28. The method of claim 25, including the step of placing a pizza box containing pizza within said container.

29. A heating method, comprising the steps of:

providing a food-holding container including a heating assembly comprising a heatable component;

providing a magnetic induction heater including a magnetic field generator for generating a magnetic field, and a resonant induction heater circuit;

placing said container in an operative position adjacent said heater so that, when a magnetic field of sufficient strength is generated by said field generator, said component is heated; and

maintaining said component in a heated condition by periodically raising the field strength of said field from a low level to a higher level, and maintaining the field strength at said higher level for a period of time, while said container remains in said operative position,

said temperature-maintaining step including the steps of detecting an induction heater circuit parameter whose magnitude is at least in part dependent upon the amplitude of the current passing through the resonant circuit when the container is in said operative position thereof, and maintaining the magnetic field strength of said magnetic field at said higher level in response to the magnitude, or rate of change of the magnitude, of said detected parameter.

30. The method of claim 29, said parameter being the amplitude of the current passing through said induction heater circuit.

31. The method of claim 29, further including the step of periodically lowering the field strength of said magnetic field from said higher level to said lower level while said container remains in said operative position.

32. The method of claim 29, including the step of placing a pizza box containing pizza within said container.