| 摘要 |
<p>A microwave oven has a magnetron 26 cooled by a fan 30 which generates a flow of air which is admitted to the oven cavity 10 through an inlet aperture 32, leaving the cavity through an outlet aperture 36. A grill element 22 is located in the upper part of the cavity 10 and a turntable 24 is positioned in the lower part of the cavity 10. Where the air respectively enters and leaves the cavity, thermocouples monitor air inlet (Ti) and air outlet (To) temperatures. After cooking commences, the air inlet and air outlet temperatures are monitored. After a time dependent on the load of the food item being cooked, the plot of air outlet temperature against time crosses the plot of air inlet temperature against time. The crossover point 44 of the air inlet and air outlet temperatures is used to control the remaining cooking time and the duration of energisation of the magnetron and the grill element during the remaining cooking time. <IMAGE></p> |
