Programmable oven for cooking holding and proofing comestibles

• US 5,786,568 A
• Filed: 06/11/1997
• Issued: 07/28/1998
• Est. Priority Date: 02/16/1995
• Status: Expired due to Fees

• Current Assignee: Leonhard May
• Original Assignee: Leonhard May
• Inventors: McKinney, Eugene F.
• Primary Examiner(s): Simone, Timothy F.
• Application Number:
  US08/873,320
• Time in Patent Office: 412 Days
• Field of Search: 99/325-333, 99/468, 99/476, 99/337, 99/338, 219/400, 219/402, 219/406, 219/407, 219/409, 219/399, 219/530, 219/540, 34/220
• US Class Current: 219/400
• CPC Class Codes: A21B 1/02 characterised by the heating arrangements
• CPC Class Codes: F24C 7/00 Stoves or ranges heated by electric energy stoves or ranges specially adapted for the use of two or more kinds of fuel or energy supply F24C1/02
• CPC Class Codes: F24C 7/087 of electric circuits regulating heat
• CPC Class Codes: Y02P 60/80 Food processing, e.g. use of renewable energies or variable speed drives in handling, conveying or stacking

Abstract

A holding oven designed for creating a natural convection current in the chamber of the oven, and constructed by fixing the heater element to a first material characterized by its high thermal conductivity for rapid build-up of thermal gradient into an insulated space, while that heater element is simultaneously in contact with a second material which is characterized by its high thermal capacitance for slowing thermal discharge upon repeated opening and closing of oven doors. The first material forms a heat conductor and the second material forms a heat sink and the heat conductor is adapted to maintain a safe holding temperature over a more extended period of time in a power off mode. An ergonomically designed operating panel provides an interactive intuitive method of programming the desired cooking sequences. Remote operation and programming is accomplished using preprogrammed software on a conventional home computer via a modem. Switch selections are monitored by a microprocessor which branches to the various preprogrammed functions. In addition, self-analysis and self-diagnostics aid the user in displaying a walk-back of the stored times and temperatures that occurred during an operating cycle before a power outage.

Claims

1. An upstanding oven cabinet having a compartment to cook and hold comestible foods with at least one door for access to the compartment, an oven circuit with a heater means and an energy source with electric current to the oven, comprising:

a heat sink comprising a first material characterized by a high thermal capacity, and a heat conductor comprising a second material characterized by a high thermal conductivity, the heater means contacting the first material and further in contact with the second material;

wherein the heater means comprises heating element including a Nichrome wire wrapped around and insulated with mica, and sheathed in a metal jacket; and

,

an inner chamber formed by a thermal baffle to smooth out heat flow and minimize heat variations within the chamber.

2. The oven for comestible foods according to claim 1, wherein the metal jacket comprises a Calrod unit.

3. The oven for comestible foods according to claim 2, wherein first material is comprises stainless steel.

4. The oven for comestible foods according to claim 3, wherein the second material comprises aluminum.

5. The oven for comestible foods according to claim 4, further comprising a heater mounting clamp associated with the oven.

6. The oven for comestible foods according to claim 5, wherein the clamp comprises a mounting plate with brackets dimensioned to receive the heater means, adapted to secure the heater means against the heat conductor and prevent the heater means from bowing away from the conductor.

7. The oven for comestible foods according to claim 6, wherein the heater means and the associated mounting plate with brackets form a heat sink.

8. The oven for comestible foods according to claim 7, further comprising a plurality of temperature sensors on the circuit in communication with the heat sink, whereby the oven is controlled to attain a desired temperature.

9. The oven for comestible foods according to claim 8, wherein the thermal baffle comprises stainless steel.

10. The oven for comestible foods according to claim 9, further comprising a means for creating a natural convection current within the cabinet, said means for creating a natural convection current comprises the conductor, constructed of opposed L-shaped pieces, each of the L-shaped pieces having an upright leg and a contiguous foot portion, with the heater means affixed to the cabinet under the juncture of the foot and the leg of each L piece, and the leg of each L-shaped piece draws heat up the sidewall of the conductor and away from the central floor portion of the cabinet, to create a convection heat flow within the cabinet, that enhances temperature control for reducing temperature variations within the oven.

11. The oven for comestible foods according to claim 10, wherein each of the L-shaped aluminum pieces is rigidly coupled to the stainless steel inner chamber, whereby the high resistivity and low conductivity of the stainless steel effectively holds moisture and water vapor in equilibrium in the oven for enhanced tenderness with reduced shrinkage of a comestible food product.

12. The oven for comestible foods according to claim 11, wherein the mass of the stainless steel compartment is more than 2 times the mass of the L-shaped aluminum pieces, thereby smoothing the flow of thermal energy in the oven.

13. The oven for comestible foods according to claim 12, each heating element having an operating temperature that is the same, whereby the thermal gradient between the heating elements is essentially zero, resulting in no flow of heat energy between them.

14. The oven for comestible foods according to claim 13, wherein the L-shaped aluminum pieces are not one contiguous material, but the foot portions of the L-shaped pieces are welded together to form a U-shaped heat conductor section.

15. The oven according to claim 14, wherein the oven has a generally rectangular shape and further comprises outer oven walls, an inner skin forming the oven compartment, and at least one door for access to the compartment.

16. The oven according to claim 15, wherein the compartment inner skin is separated from the oven walls by an insulation.

17. The oven according to claim 16, wherein the insulation is fiberglass insulation.

18. The oven according to claim 17, further comprising a multi-level, multi-functional programmable controller on the circuit, the controller having a microprocessor with a memory communicating with a front panel control board for interactively programming oven operation in real-time by controlling the current to the heating elements, and further communicating with a modem for remote programming by use of a conventional personal computer.

19. The oven according to claim 18, further comprising a power management system on the circuit for memory storage of power outages, a duration thereof, and an internal oven temperature consequent to each said outage, with an alarm indicator to provide a warning that a power supply fault has occurred.

20. The oven according to claim 19, further comprising a probe communicating on the circuit and the probe inserted into a food item to determine an internal temperature of the food item and to automatically start a cooking cycle when the internal temperature exceeds a predetermined temperature.

21. The oven according to claim 20, further comprising a battery for backup power for the microprocessor and memory in the event of an interruption in power to the oven.

22. The oven according to claim 21, further comprising functional modes of operation that include a mode for roasting and baking, a mode for holding at temperature and a mode for proofing of food items.

23. The oven according to claim 22, further comprising a thermal input into the oven chamber that is dependent on the current flowing through the heating elements.

24. The oven according to claim 23, the plurality of temperature sensors further comprising a first sensor for measuring an internal oven air temperature;

and a second sensor associated with the probe for directly measuring the internal temperature of the food item.

25. The oven according to claim 24, the microprocessor having a program that calculates the current required to produce the desired temperature as determined by the temperature sensors.

26. The oven according to claim 25, further comprising a plurality of steering diodes to establish isolation between the two power sources.

27. The oven according to claim 26, further comprising a varistor that is connected across an AC source voltage at the input of the DC power supply to provide transient surge voltage protection.

28. The oven according to claim 27, further comprising four mode switches connected to the microprocessor to provide a selection of four operational functions that include preheat, roast, probe and hold, that can be selected by either a manual or automatic means.

29. The oven according to claim 28, further comprising a means to program oven operation in automatic mode.

30. The oven according to claim 29, wherein the means to program oven operation in automatic mode comprises program select switches on the control panel, the program select switches serving as inputs to the microprocessor for selection and storage of a cooking sequence in the microprocessor memory.

31. The oven according to claim 30, further comprising a means for self-analyzing oven operations.

32. The oven described in claim 31, wherein the means for self-analyzing oven operations comprises in combination, a plurality of time data select switches and a time display having up and down push-buttons adapted for scrolling the time display to show the various times stored in memory;

a plurality of temperature select switches and a temperature display having up and down push-buttons adapted for scrolling the temperature display to show the various temperatures stored in memory;

a plurality of status LED'"'"'s with display indicators showing a current status of oven activity and a clear status button for status reset.

33. The oven of claim 32, wherein the control panel further comprises cycle start and stop push-buttons, power on and power off push-buttons.

34. The oven according to claim 33, wherein the microprocessor comprises a Motorola MC 68705R5S.

35. The oven according to claim 34, wherein the microprocessor comprises 24 bi-directional I/O lines and 8 unidirectional I/O lines.

36. The oven according to claim 35, wherein the microprocessor memory comprises an EEPROM memory which stores the control algorithm program code and executes the code.

37. The oven according to claim 36, the heating elements further comprising a bank of quartz lamps.

38. A programmable oven for preparation of comestibles, comprising:

a one-piece, free standing oven cabinet having a chamber adapted to be heated by a plurality of heater elements to a designated chamber temperature, an oven circuit with a bank of heating elements in the circuit for providing heat to the chamber, and a means for protection against a transient surge voltage said means for protection connected across an AC source voltage at the input of a first DC power supply for providing a current to the circuit and to the elements;

a microprocessor with a memory and an ADC converter with a plurality of ADC input channels, the microprocessor communicating with the first power supply and with a second back-up power supply through steering diodes for isolation between the first and said second power supply, the diodes adapted to block current flow from the back-up power supply when the first power supply is active; and

,

means for controlling chamber temperature associated with the microprocessor.

39. The programmable oven of claim 38, wherein the means for controlling comprises a control algorithm which is stored in the microprocessor memory and first temperature sensor to measure the chamber temperature and a second temperature sensor comprising a thermal probe associated with a food product within the chamber for measuring internal temperature of the product, the first and second temperature sensors connected to a respective ADC channel of the plurality for inputs to the microprocessor;

a plurality of solid state drivers on output from the microprocessor for controlling current flow to the heater elements.

40. The programmable oven in claim 39, wherein said means for protection against a transient surge voltage is a Varistor.

41. The programmable oven as described in claim 40, further comprising a means to select operation in a manual mode.

42. The programmable oven described in claim 41, wherein the means to select operation in manual mode comprises a control panel having a plurality of mode switches as inputs to the microprocessor for selection among a plurality of oven operating functions.

43. The programmable oven according to claim 42, further comprising a means to program oven operation in automatic mode.

44. The programmable oven in claim 43, wherein the means to program oven operation in automatic mode comprises program select switches on the control panel, the program select switches serving as inputs to the microprocessor for selection and storage of a cooking sequence in the microprocessor memory.

45. The programmable oven for preparation of comestibles as described in claim 44, further comprising a means for audible output from the microprocessor upon successful completion of the program entry, the four mode switches, program switches and audible output serving as a user friendly interface with an operator of the oven.

46. A process for programming a programmable oven having capabilities integrated therein for cooking, holding, and proofing comestible foods, the oven comprising an oven cabinet having a chamber adapted to be heated by a plurality of heater elements to a designated chamber temperature, an oven circuit with a bank of heating elements in the circuit for providing heat to the chamber, and a means for protection against a transient surge voltage said means for protection connected across an AC source voltage at the input of a first DC power supply for providing a current to the circuit and to the elements;

an oven controller comprising a microprocessor with a memory, a modem, and an ADC converter with a plurality of ADC input channels, the microprocessor communicating with the first power supply and with a second back-up power supply through steering diodes for isolation between the first and said second power supply, the diodes adapted to block current flow from the back-up power supply when the first power supply is active;

means for controlling chamber temperature associated with the microprocessor;

the means for controlling comprises a control algorithm which is stored in the microprocessor memory and first temperature sensor to measure the chamber temperature and a second temperature sensor comprising a thermal probe associated with a food product within the chamber for measuring internal temperature of the product, the first and second temperature sensors connected to a respective ADC channel of the plurality for inputs to the microprocessor;

a plurality of solid state drivers on output from the microprocessor for controlling current flow to the heater elements;

wherein said means for protection against a transient surge voltage is a Varistor;

wherein the microprocessor comprises 24 bi-directional I/O lines and 8 unidirectional I/O lines;

further comprising a means to select operation in a manual mode, the means to select operation in manual mode comprising a control panel having a plurality of mode switches as inputs to the microprocessor for selection among a plurality of oven operating functions;

said plurality of mode switches comprising four mode switches for selection among the four oven operating functions, preheat, roast, probe and hold modes, as inputs to the microprocessor;

a means to program oven operation in automatic mode, including remote programming via the modem by use of a personal computer;

wherein the means to program oven operation in automatic mode comprises program select switches on the control panel, the program select switches serving as inputs to the microprocessor for selection and storage of a cooking sequence in the microprocessor memory;

the oven further comprising a means for audible output from the microprocessor upon successful completion of the program entry, the four mode switches, program switches and audible output serving as a user friendly interface with an operator of the oven;

further comprising a means for self-analyzing oven operations, said means for self-analyzing comprising in combination, a plurality of time data select switches and a time display having up and down push-buttons adapted for scrolling the time display to show the various times stored in memory;

a plurality of temperature select switches and a temperature display having up and down push-buttons adapted for scrolling the temperature display to show the various temperatures stored in memory;

a plurality of status LED'"'"'s with display indicators showing a current status of oven activity and a clear status button for status reset;

the oven further comprising a means to reset the current status of oven activity following self-analyzing oven operations;

wherein the means to reset the current status of oven activity comprises a clear status button of the control panel;

wherein the control panel further comprises cycle start and stop push-buttons, power on and power off push-buttons;

further comprising a set button for display of the set temperature and an actual button to display the actual temperature reading;

the plurality of heater elements comprising Calrod heating elements and a bank of quartz lamps, comprising the steps of;

depressing a Select push-button "n" times until a desired "Program Select" area is reached, whereby for each push of the Select push-button, the next LED in sequence is illuminated showing the current program area;

entering the Start Time by scrolling the Time Display with Up Arrow and Down Arrow push-button switches respectively;

depressing the Enter push-button to advance the display to the next digit, whereby when the last digit is entered into the display, the program sequence automatically advances to Date display and the date advances with each push of the Enter push-button;

depressing the Enter push-button for at least 3 seconds to store the data into memory when the Time and Date entry is accurate and complete;

selecting the "Auto Preheat" mode if so desired;

entering the desired preheat temperature if the "Auto Preheat" function is selected;

entering the temperature by the same data entry process;

selecting the oven mode function by depressing the appropriate mode push-button;

entering the Time and Temperature selections;

activating a Hold function pushing the Hold push-button;

entering the Hold Temperature and the Hold Time;

depressing and holding the Select push-button for at least 3 seconds to store the entire program into memory;

issuing three consecutive beeps on piezoelectric buzzer upon completion of the data entry program, for acknowledgement by the microprocessor that the data entry was successful.