Control system for cooking appliance employing radiant cooking

• US 20050236389A1
• Filed: 11/19/2004
• Published: 10/27/2005
• Est. Priority Date: 04/08/2004
• Status: Active Grant

• Current Assignee: ACP of Delaware Incorporated (ACP)
• Original Assignee: Maytag Corporation (Whirlpool Corporation)
• Inventors: Goranson, James A.
• Granted Patent: US 7,109,448 B2
• Time in Patent Office: Days
• US Class Current: 219/400
• CPC Class Codes: A21B 1/245 with a plurality of air nozzles to obtain an impingement effect on the food
• CPC Class Codes: F24C 1/14 Radiation heating stoves and ranges, with additional provision for convection heating
• CPC Class Codes: H05B 6/6485 further combined with convection heating

Abstract

A cooking appliance includes a heating system which is preferably capable of combining radiant, convection, microwave and conduction heating techniques to perform a cooking operation. The cooking appliance includes a convection fan and at least one heating element. A controller is provided to regulate a triac to maintain a desired heater intensity through phase angle firing. Essentially, an AC waveform provided to the heater resistor travels through the triac which is turned on by the controller at predetermined points in the AC waveform, with the delay from a zero point waveform crossing functioning to regulate the amount of power sent to the heater resistor. When the signal from the controller is removed, the triac advantageously turns off at the next zero crossing of the AC waveform such that an operationally and economically effective control system is provided.

Claims

1. A cooking appliance comprising:

a cabinet including top, bottom rear and opposing side walls;

a cooking chamber including top, bottom, rear and opposing side walls and a frontal opening;

a door movably mounted relative to the cooking chamber for selectively closing the frontal opening;

a heating device provided in the cabinet for performing a portion of a cooking operation, said heating device having a power rating which is sized greater than a desired power output; and

a control system for regulating an intensity of the heating device during a cooking operation by altering an AC waveform provided to the heating device, said control system including a triac, as well as a controller for turning on the triac at select points in the AC waveform to create a delay from a zero point crossing of the AC waveform, thereby altering an amount of power sent to the heating device such that the desired power output is obtained.

2. The cooking appliance according to claim 1, wherein the AC waveform is provided by first and second out-of-phase sources.

3. The cooking appliance according to claim 2, wherein the triac is arranged in series between the second source of the AC waveform and the heating device.

4. The cooking appliance according to claim 2, further comprising:

a relay connected in series between the first source of the AC waveform and the heating device.

5. The cooking appliance according to claim 4, wherein the triac is arranged in series between the second source of the AC waveform and the heating device and in parallel with the relay.

6. A cooking appliance comprising:

a cabinet including top, bottom rear and opposing side walls;

a cooking chamber including top, bottom, rear and opposing side walls and a frontal opening;

a door movably mounted relative to the cooking chamber for selectively closing the frontal opening;

a heating device provided in the cabinet for performing a portion of a cooking operation, said heating device having a power rating which is sized greater than a desired power output; and

means for regulating an intensity of the heating device during a cooking operation by altering an AC waveform provided to the heating device, said regulating means including a triac which is turned on at select points in the AC waveform to create a delay from a zero point crossing of the AC waveform, thereby altering an amount of power sent to the heating device such that the desired power output is obtained.

7. The cooking appliance according to claim 6, wherein the AC waveform is provided by first and second out-of-phase sources.

8. The cooking appliance according to claim 7, wherein the triac is arranged in series between the second source of the AC waveform and the heating device.

9. The cooking appliance according to claim 7, wherein the regulating means further comprises a relay connected in series between the first source of the AC waveform and the heating device.

10. The cooking appliance according to claim 9, wherein the triac is arranged in series between the second source of the AC waveform and the heating device and in parallel with the relay.

11. A method of performing a cooking operation while maintaining a desired intensity of a heating device in a cooking appliance:

placing a food item onto a cooking chamber of the cooking appliance;

activating a heating device, which has an oversized power rating, to create heat introduced into the cooking chamber;

providing AC power, having an AC waveform, to the heating device; and

regulating an amount of power sent to the heating device during a cooking operation by altering the AC waveform provided to the heating device by turning on a triac at select points in the AC waveform to create a delay from a zero point crossing of the AC waveform.

13. The method of claim 13, further comprising:

turning the triac on to complete a current path from a second source of the AC power to the heating device.

12. The method of claim 13, further comprising:

activating a relay to complete a current path from a first source of the AC power to the heating device.