Claims
- 1. A microwave oven, comprising: a cavity for receiving a food item to be cooked; a magnetron for delivering microwave power to the cavity; a forced hot air system including a fan and an electrical resistance heating element which are disposed in a compartment separated from the cavity by a dividing panel, said panel having a first aperture as a hot air outlet aperture for said cavity and a second aperture serving as a hot air inlet aperture for said cavity, whereby said fan draws air into said compartment from said cavity through said outlet aperture, directs the air over said heating element and then returns the air to said cavity through said inlet aperture; a first thermistor located adjacent to said fan for monitoring the variation of air temperature over time and determining the time at which the air temperature reached a predetermined value and, when the air temperature reached the predetermined value, means for:
- (1) determining the remaining cooking time, beyond the time when the air temperature reached the predetermined value to the end of the cooking by reference to a first stored pre-set characteristic that in combination with the time when the air temperature reached the predetermined value permits a determining of total cooking time, and
- (2) determining a maximum air temperature for air entering the oven through said hot air inlet aperture from the time when the temperature reached the predetermined value to the end of cooking, the determination being made by reference to a second stored pre-set characteristic using the time when the temperature reached the predetermined value to determine the maximum hot air temperature, said maximum hot air temperature being thermostatically measured and controlled by a second thermistor adjacent said inlet aperture to said cavity, immediately downstream of said heating element.
- 2. A microwave oven according to claim 1, wherein said first thermistor is located substantially midway between the outer periphery of said fan said an adjacent wall of a casing which defines the margin of said compartment.
- 3. A microwave oven according to claim 1, wherein the oven has the capability of producing a well done or a lightly done result, in addition to the normal result, based upon the time at which the predetermined temperature value is reached and the desired result, the stored first and second characteristics are adjusted to produce, in the case of the user requiring a well done result, a longer remaining cooking time and a higher maximum hot air temperature or, in the case of the user requiring a lightly done result, a shorter remaining cooking time and a lower maximum hot air temperature.
- 4. A microwave oven according to claim 1, wherein the oven has means for selecting a first program for ordinary baked items, excluding cakes, and a second program for frozen foods and cakes, the oven storing first and second characteristics data suitable for each said first and second programs such that additional cooking time, beyond the time when the temperature reaches the predetermined value, can be determined as can the maximum temperature.
- 5. A microwave oven according to claim 1, wherein the oven has means for forcing cold or predetermined cool air through said cavity in order to cool said cavity during a cool down period before a subsequent cooking operation, a thermostat to determine the temperature of the air flow and means for terminating the cool down period and initiating the cooking operation by the simultaneous application of forced hot air and microwave power when the air flow temperature drops to a predetermined cool down temperature, and wherein microwave power is applied to the cavity during the cool down period.
- 6. A microwave oven according to claim 5, wherein the cool or cold air is blown through said cavity by directing air from a magnetron cooling fan into said cavity during the cool down period.
- 7. A method of cooking food in a microwave oven having a forced hot air system including a fan and an electrical resistance heating element, comprising the steps of:
- delivering microwave power to a cavity of the oven by means of a magnetron for the entire cooking period;
- flowing air into the cavity from said hot air system measuring the time necessary for the air, as drawn from said cavity, to reach a predetermined temperature;
- calculating, using said time for the air to reach a predetermined temperature, remaining cooking time to complete cooking and a maximum air temperature for hot air entering said cavity;
- monitoring the air temperature as drawn from said cavity from said time for the air to reach a predetermined temperature until completion of cooking to control said electrical resistance heating element for raising said air temperature to no more than said maximum air temperature prior to reintroducing the air into said cavity; and
- shutting of said microwave power and hot air flow at the end of said entire cooking period.
Priority Claims (3)
Number |
Date |
Country |
Kind |
8607486 |
Mar 1986 |
GBX |
|
8607901 |
Apr 1986 |
GBX |
|
8624938 |
Oct 1986 |
GBX |
|
Parent Case Info
This is a continuation application Ser. No. 027,247 filed Mar. 18, 1987, now abandoned.
US Referenced Citations (8)
Continuations (1)
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Number |
Date |
Country |
Parent |
027247 |
Mar 1987 |
|