Steam cooking system
Improved steam ovens and methods for operating steam ovens include selectively operating a gas heating element below a water reservoir at the bottom of a cooking cavity with water present therein, a convection heating element in the cooking cavity, and a convection fan adjacent the cooking cavity in order to achieve and maintain a predetermined cooking temperature within the cooking cavity. Alternatively, where there is no heating element below a water reservoir in the cooking cavity, a convection system can be operated in order to direct heated air such that it impinges directly on water in the water reservoir, thereby converting the water to steam
1. A cooking appliance comprising:
a cooking cavity comprising a rear wall opposite an opening of the cooking cavity;
a reservoir for holding water at a bottom of the cooking cavity;
a convection heating system located adjacent to the rear wall of the cooking cavity, and comprising: a convection heating element for heating air within the cooking cavity, a fan for circulating air within the cooking cavity, and a shroud that at least partially covers the convection heating element and the fan;
wherein the convection heating system is configured to direct at least a portion of the air heated by the convection heating element into the reservoir along a direct line-of-sight on exiting the shroud in order that said portion of the air impinges directly on a surface of water within the reservoir.
2. A method of steam-baking using the cooking appliance according to claim 1 , wherein the cooking appliance further includes a gas-bake element beneath the reservoir, the method comprising:
a) receiving water in the reservoir;
b) executing a preheat phase including a first preheat stage during which the gas-bake element but not the convection heating element is energized, and thereafter a second preheat stage during which the gas-bake element, the convection heating element, and the fan are energized until a temperature in the cooking cavity reaches a setpoint temperature;
c) after the preheat phase, executing a postheat phase including a first postheat stage during which the convection heating element, the fan, and the gas-bake element are energized, and thereafter:
a. a second postheat stage wherein only the convection heating element and the fan are energized when the temperature in the cooking cavity is at least equal to the setpoint temperature; and
b. a third postheat stage wherein the convection heating element, the fan, and the gas-bake element are energized when the temperature in the cooking cavity is less than the setpoint temperature.
3. The method of claim 2 , the second preheat stage immediately following the first preheat stage.
4. The method of claim 2 , wherein the second postheat stage is operative when the temperature in the cooking cavity is at least equal to the setpoint temperature; and the third postheat stage is operative when the temperature in the cooking cavity is less than the setpoint temperature.
5. The method of claim 2 , wherein the second postheat stage and third postheat stage are operated cyclically based on the temperature in the cooking cavity.
6. The method of claim 2 , the first postheat stage further comprising providing a signal that the predetermined cooking temperature has been reached.
7. The method of claim 2 , wherein the temperature in the cooking cavity is continuously measured by a temperature sensor in the cooking cavity throughout all the preheat and postheat stages.
8. The method of claim 1 , wherein water is introduced directly to the reservoir by a user prior to executing the one or more preheat stages.
9. The method of claim 2 , wherein the reservoir is provided adjacent to or formed as part of a bottom wall of the cooking cavity.
10. The method of claim 2 , wherein the convection heating element is an electric heating element having a power rating in a range of 500 W to 1500 W.
11. The method of claim 2 , the shroud defining at least one inlet and a plurality of outlets for circulating air throughout the cooking cavity.
12. The method of claim 2 , the shroud defining an outlet directly above a portion of said reservoir that is configured to direct the air heated by the convection heating element along the direct line-of-sight.
13. The cooking appliance of claim 1 , wherein the reservoir is formed in a bottom wall of the cooking cavity.
14. The cooking appliance of claim 1 , wherein there is no heating element below the reservoir.
15. The cooking appliance of claim 1 , wherein at least portion of the reservoir is inclined such that a depth of the reservoir increases in a direction toward the rear wall and a deepest part of the reservoir is located at a rear-most portion thereof, adjacent to the rear wall of the cooking cavity.
16. A method of operating the cooking appliance according to claim 1 to cook a food item within the cooking cavity via a steam-assisted cooking process, comprising:
(a) receiving water within the reservoir;
(b) initiating a pre-heating stage, the pre-heating stage comprising energizing the convection heating element and the fan; and
(c) thereafter initiating a post-heating stage when a measured temperature in the cooking cavity reaches a predetermined temperature, the post-heating stage comprising energizing the convection heating element and the fan;
wherein during steps (b) and (c) the fan directs heated air along the direct line-of-sight to impinge directly on a surface of the water in the reservoir thereby converting at least a portion thereof to steam, and circulates heated air and steam throughout the cooking cavity;
wherein the measured temperature is continuously measured throughout the steam-assisted cooking process; and
wherein no heating element located below the reservoir is energized during the steam-assisted cooking process.
17. The method of claim 16 , wherein no additional heating element(s) are energized during the steam-assisted cooking process.
18. A method of operating the cooking appliance according to claim 1 , comprising directing a stream of heated air from the convection heating system along the direct line-of-sight to impinge on a surface of water located in the reservoir, thereby converting at least a portion of said water to steam, and circulating said steam within the cooking cavity.
19. The cooking appliance of claim 1 , said shroud defining an outlet configured to direct said portion of the air heated by the convection heating element into the reservoir along the direct line-of-sight on exiting the shroud, said outlet being directly above a portion of said reservoir.